Provider: National Science Library - National Research Council Canada / Bibliothèque scientifique nationale - Conseil national de recherches Canada Content: text/plain; charset="UTF-8" TY - CHAP TI - Laser cladding of high-performance CPM tool steels on hardened HI3 hot-work tool steel for automotive tooling applications DO - 10.1002/9781118356074.ch2 AU - Chen, Jianyin AU - Xue, Lijue T2 - Supplemental Proceedings: Materials Processing and Interfaces, Volume 1 SN - 9781118296073 SN - 9781118356074 KW - laser cladding KW - CPM tool steels KW - H13 tool steel KW - tooling DA - 2012/05/18 PY - 2012 PB - Wiley LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9eba2d74-64fa-426c-b054-cfb00327d785 ER - TY - JOUR TI - Observation of mass-independent fractionation in MC-ICPMS and its implication for accurate isotope ratio measurements AU - Yang, L. AU - Mester, Z. AU - Sturgeon, R. E. AU - Meija, J. T2 - Geophysical Research Abstracts T3 - European Geosciences Union (EGU) General Assembly 2012, April 22-27, 2012, Vienna, Austria VL - 14 SP - EGU2012-1495-1 AB - Today, MC-ICPMS has become a powerful research tool for the high precision isotope ratio measurements with over five-hundred papers published annually in the past several years1-2. However, MC-ICPMS suffers approximately tenfold larger bias (up to 25 % for lithium3) in isotope amount ratio measurements as compared to thermal ionization mass spectrometry (TIMS). This bias needs to be properly corrected in order to obtain accurate isotope amount ratio measurements. The choice of the fractionation law to calibrate (correct) measured isotope ratios is crucial in isotope science. Over the last decades, the Russell law mass bias correction model (Eq. 1)4 which is applicable only for mass-dependent fractionation and assumes identical mass bias for both the calibrator and measurand elements, has become a standard curriculum in isotope ratio measurements. However, it has been reported that not only mass bias is different for different elements but also that the mass bias is different for different isotope pairs of a same element5-6. Mass-independent fractionation in MC-ICPMS has been observed for elements such as Nd, W and Cd5-7. Ri,j = ri,j(mi/mj)-f (1) Here Ri,j = n(iE)/n(jE), ri,j is the measured (uncorrected) isotope ratio and E is the element of interest, f is the fractionation function and mi,mj are the nuclide masses. In this talk, recent research results on MIF observed for Ge, Hg and Pb in MC-MCP in our group8 will be presented and its implication for Russell law mass bias correction for isotope amount ratio measurements will be presented and discussed. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 02434863-2d62-4f45-b6e4-41550aaaa63f ER - TY - CHAP TI - Cerebral ischemia induced proteomic alterations: consequences for the synapse and organelles DO - 10.5772/32035 AU - Costain, Willard J. AU - Haqqani, Arsalan S. AU - Rasquinha, Ingrid AU - Giguere, Marie-Soleil AU - Slinn, Jacqueline T2 - Advances in the Preclinical Study of Ischemic Stroke SN - 978-953-51-0290-8 SP - 85 EP - 116 DA - 2012/03/16 PY - 2012 PB - Intech LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c332e7d9-8042-4aff-a72a-ad3c82fc6ab7 ER - TY - JOUR TI - Addressing the challenge of inspecting buried nuclear piping in nuclear power plants DO - 10.1115/PVP2012-78794 AU - Angell, Peter AU - Wang, Sheng-Hui AU - Simon, Phil AU - Kleinfelder, Hank AU - Garrity, Kevin AU - Sisk, Elizabeth T2 - ASME 2012 Pressure Vessels and Piping Conference: Volume 1, Codes and Standards T3 - ASME 2012 Pressure Vessels and Piping Conference, July 15-19, 2012, Toronto, Ontario, Canada SN - 978-0-7918-5500-3 SP - PVP2012-78794 SP - 291 EP - 297 AB - Similar to many other industries, nuclear power plants (NPPs) have many kilometres of buried pipe that is not readily accessible for direct inspection. Given the nature of the systems, the nuclear industry experiences additional challenges as many services run in the same area, leading to what is described as a “spaghetti bowl” of piping. As a result, the traditional indirect, over the line, inspection practices developed for the oil and gas industry have not always been successfully applied at nuclear power plants. To address this issue, a collaborative Electric Power Research Institute/CANDU Owners Group (EPRI/COG) research project was established with Mears Group Inc. and Atomic Energy of Canada Limited (AECL) Nuclear Laboratories. In this program, initial testing of four methods was carried out at the Mears Group Inc, test site that had been modified with additional grounding systems to simulate a nuclear power plant. This was followed by testing of the same methods at the AECL Nuclear Laboratories Chalk River site. This paper will discuss the results of those studies and present some of the findings that were made that can help to overcome the challenges faced by Nuclear Power Plants. DA - 2012/07/15 PY - 2012 PB - ASME LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1dd78ce1-0b98-4802-852c-68e907e1a063 ER - TY - CHAP TI - Unsupervised data analysis methods used in qualitative and quantitative metabolomics and metabonomics DO - 10.4018/978-1-61350-435-2.ch001 AU - Cuperlovic-culf, Miroslava T2 - Systemic Approaches in Bioinformatics and Computational Systems Biology T2 - Advances in Bioinformatics and Biomedical Engineering SN - 2327-7033 SN - 2327-7041 SN - 9781613504352 SN - 9781613504369 SP - 1 EP - 28 AB - Metabolomics or metababonomics is one of the major high throughput analysis methods that endeavors holistic measurement of metabolic profiles of biological systems. Data analysis approaches in metabolomics can broadly be divided into qualitative – analysis of spectral data and quantitative – analysis of individual metabolite concentrations. In this work, the author will demonstrate the benefits and limitations of different unsupervised analysis tools currently utilized in qualitative and quantitative metabolomics data analysis. Following a detailed literature review outlining different applications of unsupervised methods in metabolomics, the author shows examples of an application of the major previously utilized unsupervised analysis methods. The testing of these methods was performed using qualitative as well as corresponding quantitative metabolite data derived to represent a large set of 2,000 objects. Spectra of mixtures were obtained from different combinations of experimental NMR measurements of 13 prevalent metabolites at five different groups of concentrations representing different phenotypes. The analysis shows advantages and disadvantages of standard tools when applied specifically to metabolomics. DA - 2012 PY - 2012 PB - Medical Information Science Reference LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c5de7866-858f-4239-bcfe-85d27de1f2a7 ER - TY - JOUR TI - Abstract 2532: integrated therapeutic antibody development at the National Research Council of Canada DO - 10.1158/1538-7445.AM2012-2532 AU - Jaramillo, Maria Luz AU - O'connor-McCourt, Maureen T2 - Cancer Research SN - 0008-5472 SN - 1538-7445 VL - 72 IS - 8 Supplement SP - 2532 EP - 2532 AB - Advances in genomics and antibody engineering have enabled the development of an innovative class of targeted therapies to provide new treatment options for diseases with significant unmet medical needs such as cancer. Therapeutic antibodies represent one of the fastest growing classes of medications with sales anticipated to exceed $30 billion globally by 2012. The NRC has built a chain of cutting edge technology platforms needed to discover, engineer and produce therapeutic monoclonal antibodies with the goal of partnering with industrial and academic centers to advance research and development of this important class of therapeutics. Target Identification- To establish and validate the technology platform, tumor targets for candidate therapeutic antibody production were identified using a combination of proteomics, transcriptomics and bioinformatic approaches. Out of these lists, approximately 40 tumor targets were selected (known therapeutic antibody targets were excluded), and over 2,000 antibodies of mouse and camelid origin were then generated against these targets. Antibody generation- Once identified, the recombinant target protein of interest can be produced using the NRC's high efficiency cell expression platforms in CHO or HEK293 cells and purified protein used for immunization or panning. For targets which are difficult to express or purify, the capabilities for direct immunization with plasmid DNA constructs provides another option. Clone selection is carried out by ELISA and typically 50 antibodies/target are identified for further characterization. Antibody characterization and validation- The affinities of the antibodies are determined by SPR biosensor analysis. Reverse phase protein arrays and Western blot analysis on protein mixes and cell lines allow the characterization of the specificity of the antibodies. Epitope mapping can be carried out so that representative antibodies from each epitope bin can be selected for further validation in appropriate cell-based assays (many of which are established at NRC) and animal models. Therapeutic antibody Optimization, Bioprocessing and Biomanufacturing- Therapeutic antibodies selected for development can be further optimized using antibody engineering technologies to humanize them and/or modify their glycosylation patterns to improve their effector function, pharmacokinetics, solubility and stability as well as reduce their immunogenicity. The NRC platform for large scale protein production has the capacity to manufacture up to 13.5 g of commercial grade antibody using serum free, low endotoxin media in a cGMP certified CHO cell line which is ready for transfer to CMOs or other industrial partners. DA - 2012/04/15 PY - 2012 PB - American Association for Cancer Research LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 43e3adb3-7a37-4997-8810-9a01dd13295c ER - TY - JOUR TI - Application of metabolomics in drug discovery, development and theranostics DO - 10.2174/2213235X130105 AU - Cuperlovic-Culf, Miroslava AU - S. Culf, Adrian AU - Jr Morin, Pier AU - Touaibia, Mohamed T2 - Current Metabolomics SN - 2213-235X SN - 2213-2368 VL - 1 IS - 1 SP - 41 EP - 57 KW - bioreactors; drug discovery; drug testing; fluxomics; metabolomics; theragnostics imaging; theragnostics treatment planning; systems biology AB - High throughput analysis of metabolites combined with systems biology is opening new opportunities in medical research and clinical applications. Investigation of metabolic phenotype and metabolic requirements of a disease opens new avenues for treatments. Analysis of metabolic changes in patients and in disease models following treatments provides new methods for investigation of therapeutic response. Combined examination of disease metabolic characteristics and treatment response provides markers for personalization of therapies. Metabolomics finds itself at an increasingly important junction in all of these applications. In this review, we will explore the advantages of combining metabolomics with systems biology to optimize the drug discovery process via in-depth analysis of biological systems and novel metabolism- targeted therapeutics. Assessment of efficacy and specificity of drugs that directly or indirectly target metabolism through analyses of metabolic changes will also be presented. Finally, we will highlight examples of metabolic biomarkers explored as promising theranostics and theranostic imaging tools aimed at therapy optimization and combined therapy and diagnostics. The focus of this review will be directed towards cancer, however, the overarching ideas as well as experimental and analysis approaches are easily transferable to other applications. In cancer research, metabolism is once again raising interest due to a better appreciation of the significance of altered metabolic phenotype in cancer development and progression. Investigation of metabolic changes in cancer following drug applications and identification of clinically relevant metabolic markers for particular cancer subtypes are becoming increasingly appreciated in treatment development and will be explored in this review. DA - 2012/11/01 PY - 2012 PB - Bentham Science LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6460a898-7d1c-4786-b233-9a31c44029b4 ER - TY - CHAP TI - Oilseed crop productivity under salt stress DO - 10.1007/978-1-4614-4747-4_9 AU - Nayidu, Naghabushana AU - Bollina, Venkatesh AU - Kagale, Sateesh T2 - Ecophysiology and Responses of Plants under Salt Stress SN - 978-1-4614-4746-7 SN - 978-1-4614-4747-4 SP - 249 EP - 265 KW - Plant breeding KW - Plant genetics KW - Plant physiology AB - Agricultural production around the world, especially where it mainly depends on irrigation, is confronted with serious challenges of coping with soil salinity conditions as well as saline irrigation water. Soil salinity is increasing regularly throughout the world and has become a great menace for agriculture. About 800 million hectares of the world land are salt-affected, of which 397 million hectares are saline and 434 million hectares sodic. Soil salinity adversely affects crop growth and productivity. In oilseed crops, salt stress affects both vegetative and reproductive growth stages by reducing growth, delaying the onset of flowering, reducing the quantum of reproductive structures and delaying the maturation processes, ultimately leading to diminished crop yield. Additionally, it affects production of several enzymes leading to the reduction of glycerides and modification of the fatty acid profile, important quality determinants of seed oil. Thus, salt stress has become a major factor affecting oilseed production worldwide. Here, we have reviewed the effects of salt stress on growth and productivity of oilseed crops. Additionally, different strategies employed by crop plants against salt stress as well as research reports describing genetic and transgenic approaches designed for improving plants ability to overcome salt stress are discussed. DA - 2012/10/09 PY - 2012 PB - Springer International Publishing LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ff848714-46c9-44ba-96d5-bc46a96244e6 ER - TY - CHAP TI - Advances in microspore culture technology: a biotechnological tool for the improvement of medicinal plants DO - 10.1007/978-3-642-29974-2_8 AU - Ferrie, Alison M. R. T2 - Biotechnology for Medicinal Plants SN - 978-3-642-29973-5 SN - 978-3-642-29974-2 SP - 191 EP - 206 KW - Plant Physiology KW - Cell culture KW - Biotechnology KW - Pharmacology KW - Toxicology AB - Doubled haploidy techniques are well established for some species and are routinely used for practical application and basic research. Haploid/doubled haploid plants can be produced via a number of ways although the in vitro methods of androgenesis (culture of the male gametophyte) or gynogenesis (culture of the female gametophyte) are the most common. For medicinal plants, very little genetic improvement has been undertaken when compared to major crop species. However, callus, embryos, and doubled haploid plants have been produced in several medicinal species using a range of media formulations and culture conditions. This chapter focuses on doubled haploid production from the male gametophyte and the factors influencing this response.Doubled haploidy methodology would be beneficial for medicinal species as uniform, homozygous, true breeding lines would be available for growers. Uniformity in plants and in the active ingredient is very important for regulatory standards and for those conducting clinical trials. DA - 2012/08/08 PY - 2012 PB - Springer International Publishing LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1397f3aa-d03e-41e0-8809-d0a69ca7384d ER - TY - CHAP TI - Effect of nanoparticles on electrolytes and electrode/electrolyte interface DO - 10.1007/978-1-4614-4605-7_9 AU - Salem, Nuha AU - Abu-Lebdeh, Yaser T2 - Nanotechnology for Lithium-Ion Batteries T2 - Nanostructure Science and Technology SN - 1571-5744 SN - 978-1-4614-4604-0 SN - 978-1-4614-4605-7 SP - 221 EP - 244 AB - The addition of nano-sized inorganic fillers such as SiO2 to solid and liquid electrolytes to enhance their electrochemical and physical properties has been recently the focus of great deal of research. In this chapter, we review the work done in this area where various types of nanoparticles including ceramics and clay were used as additives to electrolytes commonly used in lithium-ion batteries research such as polymer electrolytes (gel and solid form), ionic and organic liquid electrolytes and plastic crystals. DA - 2012/08/31 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 064bcd96-e265-46a0-9cb5-edf05473a68e ER - TY - GEN TI - Combination of High Spatial Resolution LII and LOSA measurements for determination of soot volume fraction and PAH concentration in laminar diffusion flames AU - Leschowski, M. AU - Thomson, K. AU - Clavel, D. AU - Snelling, D. AU - Schulz, C. AU - Smallwood, G. T2 - Laser-induced Incandescence 2012 T2 - CEUR Workshop Proceedings; no. 865 T3 - 5th international workshop on Laser-Induced Incandescence, May 9-11, 2012, Palais des Congrès, Le Touquet, France SN - 1613-0073 DA - 2012 PY - 2012 UR - http://ceur-ws.org/Vol-865/ LA - eng N1 - Presented at poster session N1 - Présentée à la séance de présentation par affiches, session C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 94dc268d-7f02-4177-8f90-fd96f0591e10 ER - TY - JOUR TI - Carbon-supported iridium catalyst for reduction of chlorate ions with hydrogen in concentrated solutions of sodium chloride DO - 10.1016/j.apcata.2012.03.024 AU - Kuznetsova, Lidia I. AU - Kuznetsova, Nina I. AU - Koscheev, Sergei V. AU - Zaikovski, Vladimir I. AU - Lisitsyn, Alexander S. AU - Kaprielova, Ksenia M. AU - Kirillova, Natalia V. AU - Twardowski, Zbigniev T2 - Applied Catalysis A: General SN - 0926-860X VL - 427-428 SP - 8 EP - 15 AB - In production of chlorine by electrolysis of NaCl, chlorate is formed as by-product and must be removed. The back conversion of ClO3− to Cl− via catalytic reduction with H2 on Ir catalyst in NaCl brine has been studied. The catalysts contained 0.5–5 wt.% of Ir and were prepared via impregnation of mesoporous carbon support (Sibunit™) with solutions of IrCl3·xHCl·yH2O or H2IrCl6 and reduction in flowing H2 at 400 or 500 °C. The Ir/C samples have been characterized with CO adsorption, XPS and HRTEM. The rate of ClO3− reduction in concentrated solutions of NaCl was found dependent on pH (in the range 2–6), content of Ir in the catalyst, dispersion and distribution of Ir on the support. The best properties have been shown by 5%Ir/C catalyst which was prepared with H2IrCl6 as the metal precursor and contained small Ir particles (∼1.5 nm in diameter) located inside the cavities of carbon globules. Stable catalytic performance in multiple successive runs has been achieved. DA - 2012/06/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 713e42f2-b0cf-48e8-ada7-eb72b4a9bbbf ER - TY - JOUR TI - Study of true stress-strain curve after necking for application in ductile fracture criteria in tube hydroforming of aerospace material DO - 10.4028/www.scientific.net/KEM.504-506.95 AU - Saboori, M. AU - Champliaud, H. AU - Gholipour, J. AU - Gakwaya, A. AU - Savoie, J. AU - Wanjara, P. T2 - Key Engineering Materials SN - 1013-9826 VL - 504-506 SP - 95 EP - 100 KW - Work hardening law; Material behaviour; Weighted average method; Diffuse necking AB - The increased demand for weight reduction and manufacture of complex shapes with tube hydroforming (THF) requires more accurate material models to achieve highly reliable results from simulations. Conventional flow behaviours of materials implemented in commercial finite element (FE) software are not capable of describing accurately the material behaviour after localization. Utilization of the stress-strain data after necking can improve the quality of the FE analysis by employing realistic data for extrapolating the stress-strain curve. In this paper, the objective was to develop a simple tool that can determine the true stress-strain curve after necking in order to predict the material behaviour of aerospace alloys such as stainless steel 321 (SS321). Standard uniaxial tensile tests (ASME E8M-04) were performed to determine the true stress-strain before necking. A weighted-average method and a new hardening equation were proposed to extend the curve after necking. DA - 2012/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 491d95a2-c344-4100-9118-0644c2b06219 ER - TY - JOUR TI - Increasing the hydroformability of stainless steel 321 by multistep processing AU - Anderson, Melissa AU - Bocher, Philippe AU - Gholipour, Javad AU - Jahazi, Mohammad AU - Savoie, Jean AU - Wanjara, Priti T2 - Steel Research Journal SN - 1611-3683 SP - 1243 EP - 1246 KW - Stainless steel; multistep forming; free expansion tests; heat treatment; tube hydroforming AB - The application of the tube hydroforming process for the manufacture of aerospace components is relatively new and challenging due to the limited formability of high strength alloys used for aerospace applications. A multistep forming process, including intermediate heat treatment steps, has been proposed as a viable solution for increasing the hydroformability of these alloys. Interrupted free expansion tests were used in this study to emulate the multistep forming. Initially, free expansion tests were performed up to the burst point to determine the maximum pressure. An automated 3D deformation measurement system, ARAMIS®, was used to measure the strain distribution along the tube length as well as to measure the bulge height (expansion) as a function of time. Based on the strain distribution results obtained from ARAMIS®, a pause pressure corresponding to about 80% of the burst or maximum pressure was selected as the interruption point of the free expansion test in order to apply a softening heat treatment to restore the formability of the material. After this free expansion and softening cycle, the tube was then hydroformed up to the burst point.The results indicated that the inclusion of an intermediate heat treatment before the second forming step increased the expansion from 9.5 mm to 12 mm, a 26% increase. Interestingly, in addition to the higher expansion, the pressure required to reach a specific level of expansion was reduced by half due to the softening effect of the intermediate heat treatment and thinning of the tubes from the first forming step. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6b05cd47-8cce-4f80-a90c-92441f21241b ER - TY - JOUR TI - The GALEX Ultraviolet Virgo Cluster Survey (GUViCS) II. Constraints on star formation in ram-pressure stripped gas DO - 10.1051/0004-6361/201219957 AU - Bossier, S. AU - Boselli, A. AU - Duc, P.-A. AU - Cortese, L. AU - van Driel, W. AU - Heinis, S. AU - Voyer, E. AU - Cucciati, O. AU - Ferrarese, L. AU - Côté, P. AU - Cuillandre, J.-C. AU - Gwyn, S.D.J. AU - Mei, S. T2 - Astronomy and Astrophysics SN - 0004-6361 VL - 545 SP - A142 KW - galaxies; Virgo; star formation; astronomy AB - Context. Several galaxies in the Virgo cluster are known to have large H i gas tails related to a recent ram-pressure stripping event. The Virgo cluster has been extensively observed at 1539 Å in the far-ultraviolet for the GALEX Ultraviolet Virgo Cluster Survey (GUViCS), and in the optical for the Next Generation Virgo Survey (NGVS), allowing a study of the stellar emission potentially associated with the gas tails of 8 cluster members. On the theoretical side, models of ram-pressure stripping events have started to include the physics of star formation. Aims. We aim to provide quantitative constraints on the amount of star formation taking place in the ram-pressure stripped gas, mainly on the basis of the far-UV emission found in the GUViCS images in relation with the gas content of the tails. Methods. We have performed three comparisons of the young stars emission with the gas column density: visual, pixel-by-pixel, and global. We have compared our results to other observational and theoretical studies. Results. We find that the level of star formation taking place in the gas stripped from galaxies by ram-pressure is low with respect to the available amount of gas. Star formation is lower by at least a factor 10 compared to the predictions of the Schmidt Law as determined in regular spiral galaxy disks. It is also lower than measured in dwarfs galaxies and the outer regions of spirals, and than predicted by some numerical simulations. We provide constraints on the star formation efficiency in the ram-pressure stripped gas tails, and compare these with current models. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9b65513d-ecb5-42a0-b1bc-efa147159453 ER - TY - BOOK TI - Nanofabrication: techniques and principles DO - 10.1007/978-3-7091-0424-8 AU - Stepanova, Maria AU - Dew, Steven SN - 9783709104248 SN - 3709104238 SN - 9783709104231 AB - Intended to update scientists and engineers on the current state of the art in a variety of key techniques used extensively in the fabrication of structures at the nanoscale. The present work covers the essential technologies for creating sub 25 nm features lithographically, depositing layers with nanometer control, and etching patterns and structures at the nanoscale. A distinguishing feature of this book is a focus not on extension of microelectronics fabrication, but rather on techniques applicable for building NEMS, biosensors, nanomaterials, photonic crystals, and other novel devices and structures that will revolutionize society in the coming years. DA - 2012 PY - 2012 PB - Springer International Publishing LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b56ffebd-ced7-45a4-8560-2af29eb8a7b3 ER - TY - CHAP TI - Preface DO - 10.1007/978-3-7091-0424-8 AU - Stepanova, Maria AU - Dew, Steven T2 - Nanofabrication: Techniques and Principles SN - 9783709104248 SN - 3709104238 SN - 9783709104231 SP - v EP - vi DA - 2012 PY - 2012 PB - Springer International Publishing LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 11899841-313f-4731-8409-b007cbb6d5cd ER - TY - JOUR TI - Rescue of beta-amyloid–induced alterations in cerebrovascular protein expression by pioglitazone in APP mice: Link to functional recovery in the cerebrovasculature DO - 10.1016/j.jalz.2012.05.1556 AU - Badhwar, Aman AU - Brown, R. AU - Delaney, Christie AU - Stanimirovic, D.B. AU - Haqqani, Arsalan AU - Hamel, Edith T2 - Alzheimer's and Dementia SN - 1552-5260 VL - 8 IS - 4 SP - Supplement SP - P574 EP - P575 KW - Alzheimer's disease; amyloid precursor protein mice; pioglitazone; cerebrovascular impairment AB - Cerebrovascular dysfunction appears prior to Aβ-plaque deposition and measurable mnemonic impairment in Alzheimer's disease (AD) patients and amyloid precursor protein (APP)-expressing transgenic mice. The soluble, highly toxic Aβ-fragment generated from the amyloidogenic processing of APP is likely the primary instigator of chronic cerebrovascular insufficiency in APP mice. We recently demonstrated that the PPAR-gamma agonist, pioglitazone, is a potent drug for reversing cerebrovascular impairment at all stages of Aβ-induced pathology in APP mice. Our aims are to (a) characterize the effect of Aβ-overproduction on the cerebrovascular proteome of APP mice; (b) determine the extent to which pioglitazone rescues the Aβ-altered cerebrovascular proteome; and (c) determine the link between protein expression rescue by pioglitazone and functional recovery in the cerebrovasculature. DA - 2012/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 50e79eaa-a6de-455b-bb31-5c57caea16f6 ER - TY - JOUR TI - Quantitative proteomics of Alzheimer's-like cerebral vasculature in TGF-ß1 overexpressing mice and its perturbation by pioglitazone DO - 10.1016/j.jalz.2012.05.1742 AU - Badwar, Aman AU - Stanimirovic, D.B. AU - Haqqani, Arsalan AU - Hamel, Edith T2 - Alzheimer's and Dementia SN - 1552-5260 VL - 8 IS - 4 SP - Supplement SP - P650 KW - TGF-ß1; Alzheimer's disease; cerebral vasculature; brain AB - Elevation of transforming growth factor-beta 1 (TGFβ1), a key extracellular matrix regulator, has been documented in the brain and cerebral vasculature of Alzheimer's disease (AD) patients. Transgenic mice overexpressing TGFβ1 in the brain (TGF mice) develop AD-like vascular structural changes, impaired vasomotricity, and compromised neurovascular coupling. We have demonstrated that cerebrovascular dysfunction in both aged and young TGF mice is normalized by the peroxisome proliferator-activated receptor-γ agonist pioglitazone. Our aims are to (a) characterize the cerebrovascular proteome of TGF mice and its perturbation by pioglitazone using label-free mass spectrometry-based quantitative proteomics, and (b) identify proteins that orchestrate pioglitazone-mediated recovery of cerebrovascular function. DA - 2012/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 10f22b61-ac4e-4b82-ae3c-ed55da39516c ER - TY - JOUR TI - Imaging blood–brain barrier dysfunction in animal disease models DO - 10.1111/j.1528-1167.2012.03698.x AU - Wunder, Andreas AU - Schoknecht, Karl AU - Stanimirovic, Danica B. AU - Prager, Ofer AU - Chassidim, Yoash T2 - Epilepsia SN - 1528-1167 VL - 53 SP - Supplement s6 SP - 14 EP - 21 KW - Blood–brain barrier; Fluorescence imaging; Magnetic resonance imaging; Nuclear imaging AB - The blood–brain barrier (BBB) is a highly complex structure, which separates the extracellular fluid of the central nervous system (CNS) from the blood of CNS vessels. A wide range of neurologic conditions, including stroke, epilepsy, Alzheimer’s disease, and brain tumors, are associated with perturbations of the BBB that contribute to their pathology. The common consequence of a BBB dysfunction is increased permeability, leading to extravasation of plasma constituents and vasogenic brain edema. The BBB impairment can persist for long periods, being involved in secondary inflammation and neuronal dysfunction, thus contributing to disease pathogenesis. Therefore, reliable imaging of the BBB impairment is of major importance in both clinical management of brain diseases and in experimental research. From landmark studies by Ehrlich and Goldman, the use of dyes (probes) has played a critical role in understanding BBB functions. In recent years methodologic advances in morphologic and functional brain imaging have provided insight into cellular and molecular interactions underlying BBB dysfunction in animal disease models. These imaging techniques, which range from in situ staining to noninvasive in vivo imaging, have different spatial resolution, sensitivity, and capacity for quantitative and kinetic measures of the BBB impairment. Despite significant advances, the translation of these techniques into clinical applications remains slow. This review outlines key recent advances in imaging techniques that have contributed to the understanding of BBB dysfunction in disease and discusses major obstacles and opportunities to advance these techniques into the clinical realm. DA - 2012/11/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f238c4b8-a0a5-4398-a1ea-11280ae9b4ea ER - TY - JOUR TI - Impact of initial surface parameters on the final quality of laser micro-polished surfaces DO - 10.1117/12.908137 AU - Chow, Michael AU - Bordatchev, Evgueni V. AU - Knopf, George K. T2 - Proceedings of SPIE 8248 T3 - SPIE 8248, Micromachining and Microfabrication Process Technology XVII, January 21, 2012, San Francisco, CA, USA AB - Laser micro-polishing (LμP) is a new laser-based microfabrication technology for improving surface quality during a finishing operation and for producing parts and surfaces with near-optical surface quality. The LμP process uses low power laser energy to melt a thin layer of material on the previously machined surface. The polishing effect is achieved as the molten material in the laser-material interaction zone flows from the elevated regions to the local minimum due to surface tension. This flow of molten material then forms a thin ultra-smooth layer on the top surface. The LμP is a complex thermo-dynamic process where the melting, flow and redistribution of molten material is significantly influenced by a variety of process parameters related to the laser, the travel motions and the material. The goal of this study is to analyze the impact of initial surface parameters on the final surface quality. Ball-end micromilling was used for preparing initial surface of samples from H13 tool steel that were polished using a Q-switched Nd:YAG laser. The height and width of micromilled scallops (waviness) were identified as dominant parameter affecting the quality of the LμPed surface. By adjusting process parameters, the Ra value of a surface, having a waviness period of 33 μm and a peak-to-valley value of 5.9 μm, was reduced from 499 nm to 301 nm, improving the final surface quality by 39.7%. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 70ceb23a-3269-4164-abcc-217b9bdb7041 ER - TY - BOOK TI - Supplement to the NBC 2010 : Intent Statements AU - Canadian Commission on Building and Fire Codes, National Research Council of Canada SN - 0-660-19975-7 KW - Codes and guides DA - 2012/12/31 PY - 2012 UR - http://codes-guides.nrc.ca/IA/10NBC/intentframe.html LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2dfd4132-c14d-4841-9c88-f88ea0701805 ER - TY - JOUR TI - Characterization of triangulation-based 3D imaging systems using certified artifacts AU - Beraldin, Jean-Angelo AU - Carrier, Benjamin AU - MacKinnon, David AU - Cournoyer, Luc T2 - NCSL International Measure: The Journal of Measurement Science SN - 1931-5775 SN - 2381-0580 VL - 7 IS - 4 SP - 50 EP - 60 AB - A set of test procedures and certified artifacts to characterize the capability of short-range triangulation-based threedimensional (3D) imaging systems are presented. The approach consists of scanning metallic and coated glass certified artifacts in which the uncertainties in the associated characteristic reference values are smaller than the measurement uncertainties produced by the system under test (SUT). The artifacts were grouped on the same plate for portability. To define a set of test procedures that is practical, simple to perform and easy to understand, we utilized a terminology that is well-known in the manufacturing field, i.e., geometric dimensioning and tolerancing (GD&T). The National Research Council Portable Characterization Target (NRC-PCT) is specifically designed for the characterization of systems with depths of field from 50 mm to 500 mm. Tests were performed to validate the capability of the NRC-PCT. This paper presents these results, along with some basic information on 3D imaging systems. DA - 2012/12 PY - 2012 PB - Taylor & Francis Inc. UR - http://www.tandfonline.com/doi/abs/10.1080/19315775.2012.11721620?journalCode=ujms20 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 49a2f7a8-5434-4c7b-aeda-3fb727fe8501 ER - TY - JOUR TI - Predicting the fire-resistance of cross-laminated timber assemblies AU - Craft, S.T. AU - Desjardins, R. AU - Bénichou, Noureddine T3 - World Conference on Timber Engineering 2012, July 16-19 2012, Auckland, New Zealand KW - fire resistance; cross-laminated timber assemblies AB - This research aims to address two primary objectives which will support the North American adoption of CLT (cross-laminated timber). First, a generic calculation method for determining the fire-resistance of CLT assemblies is needed to enable producers to manufacture a number of different configurations of panels without the need to run a large number of full-scale fire tests. Second, the CLT assemblies chosen for testing have been identified as the most likely configurations to be used thereby providing test data to support the claims of fire-resistance to help satisfy the authority having jurisdiction. (...) DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d84e6ddf-c8e8-4e42-bf8f-b2f3135995bc ER - TY - JOUR TI - The impact of post-fire earthquakes on FRP-strengthened concrete structural systems AU - Bénichou, Noureddine AU - Mostafaei, Hossein AU - Green, Mark AU - Bisby, Luke AU - Kodur, Venkatesh T2 - 6th International Conference on Advanced Materials in Bridges and Structures 2012 (ACMBS-VI 2012) T3 - 6th International Conference on Advanced Composite Materials in Bridges and Structures, May 22-25 2012, Kingston ON, Canada SN - 978-1-62276-401-3 SP - 310 EP - 317 KW - FRP-strengthened concrete; fire resistance; heat transfer; structural resistance AB - This paper presents the results of a research project to study the structural fire resistance of FRP-strengthened concrete members under fire exposure. The items presented in this paper are: 1) Some of the results of an experimental program, conducted at NRC, on FRP-strengthened RC columns exposed to standard fires; 2) The numerical fire simulation models that were developed to predict the heat transfer behavior of FRP-strengthened RC columns during fire exposure; 3) the recommendations for design guidance for FRP-strengthened RC structures in fire. The paper also presents the impact of lateral loading on structural columns after fire to assess the effectiveness of structural resistance of fire-damaged FRP-strengthened building elements in case of an earthquake. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a815b87e-f894-4c09-8256-40b0f60ba54a ER - TY - JOUR TI - Performance in fire of fibre reinforced polymer strengthened concrete beams and columns: recent recent and implications for design AU - Green, Mark F. AU - Hollingshead, Kevin AU - Benichou, Noureddine T2 - Proceedings of the 7th International Conference on Structures in Fire T3 - 7th International Conference on Structures in Fire, June 6-8 2012, Zurich Switzerland KW - fire; fibre reinforced polymers; concrete; strengthening; repair; rehabilitation AB - This paper considers the fire performance of concrete beams and columns that have been strengthened with fibre reinforced polymers (FRPs). Results from four recent full-scale tests are presented. A newly developed type of insultation was employed and the thickness of the insulation (15 to 20 mm) was approximately half that provided in earlier tests. All of the members survived four hours of fire exposure. A conceptual model for design is also presented. Further research needed to fully develop the conceptual model to a more practical design tool is outlined. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6ccf7a62-7c20-48b3-8ef1-2ec7b1a98f92 ER - TY - JOUR TI - Performance of displacement ventilation in Canadian schools: field studies AU - Ouazia, B. AU - MacDonald, I.A. AU - Tardif, M. AU - Thompson, A. AU - Booth, D.G. T3 - 2012 ASHRAE Annual Conference, June 2012, San Antonio, TX, USA AB - Displacement ventilation systems take a fundamentally different approach to space conditioning than the systems found in the majority of commercial buildings, which currently use a fully mixed and dilution approach to ventilation. Displacement ventilation (DV) is an alternate air distribution method for commercial spaces, in particular schools. Previous research has shown that this type of system works well for regions where buildings require year-round cooling, however there are a growing number of buildings using this approach in Canada, where buildings require heating during winter months. A series of field studies in existing Canadian schools were carried out during the heating season over the last three years. This paper presents results from field studies conducted in schools designed for displacement ventilation with a perimeter radiant heating system. We measured several aspects of the performance of a DV systems installed in schools located in different parts of the country. The results show that the measured contaminant removal effectiveness was higher than that provided in previous studies for heating mode. In addition, key predictors of thermal comfort are also generally within limits set by ASHRAE standards. The results of these field studies provide some evidence of thermal comfort and IAQ-related benefits of DV in cold climate. However, before general conclusions are drawn, the benefits need to be confirmed in other studies. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b95aefdd-73da-44a1-a528-4e181a9c0b7a ER - TY - JOUR TI - Air change effectiveness with displacement ventilation in heating season AU - MacDonald, Iain AU - Ouazia, B. AU - Thompson, A.J.L. AU - Booth, D. T3 - ASHRAE/REHVA 7th International Confernce on HVAC in Cold Climates, November 12-14, 2012, Calgary, Canada DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f6ea459a-be92-4cfc-972a-6d5f7dfed5e9 ER - TY - JOUR TI - Historical time-domain: data archives, processing, and distribution DO - 10.1017/S1743921312000671 AU - Grindlay, Jonathan E. AU - Griffin, R. Elizabeth T2 - New horizons in time-domain astronomy: proceedings of the 285th Symposium of the International Astronomical Union held in Oxford, United Kingdom September 19 - 23, 2011 T2 - Proceedings of the International Astronomical Union; 7 T3 - 285th Symposium of the International Astronomical Union, September 19-23, 2011, Oxford, United Kingdom SN - 1743-9213 SN - 1743-9221 SN - 9781107019850 SP - 243 EP - 248 AB - The workshop on Historical Time-Domain Astronomy (TDA) was attended by a near-capacity gathering of ~30 people. From information provided in turn by those present, an up-to-date overview was created of available plate archives, progress in their digitization, the extent of actual processing of those data, and plans for data distribution. Several recommendations were made for prioritising the processing and distribution of historical TDA data. DA - 2012/04/01 PY - 2012 PB - Cambridge University Press LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : dfc8f2ce-326a-4252-aa64-66e85391f71f ER - TY - JOUR TI - Distributed H∞ control of dynamically coupled segmented telescope mirrors: design and simulation DO - 10.1016/j.mechatronics.2011.12.003 AU - Ulutas, Baris AU - Kerley, Daniel AU - Dunn, Jennifer AU - Suleman, Afzal AU - Park, Edward J. T2 - Mechatronics SN - 0957-4158 VL - 22 IS - 1 SP - 121 EP - 135 KW - Control objectives KW - Design and simulation KW - Distributed control KW - Distributed controller KW - Distributed models KW - External disturbances KW - Finite element models KW - Imaging performance KW - Large telescopes KW - Mirror design KW - Mirror shape KW - Parabolic mirrors KW - Segmented primary mirrors KW - Segmented telescope KW - Spatially-invariant KW - Support structures KW - System models KW - Thirty Meter Telescope KW - Distributed parameter control systems KW - Finite element method KW - Image resolution KW - Optical telescopes AB - Next generation telescopes are to employ segmented mirrors to realize extremely large primary mirror surfaces. For example, one of the current next generation large telescope projects, the Thirty Meter Telescope (TMT), will employ a 30 m primary mirror with 492 segments. With the high degree of segmentation, control of these segments against external disturbances to maintain the parabolic mirror shape becomes a challenging task. In this paper, a preliminary study of H ∞ control of the segmented primary mirror is presented. Both spatially-invariant distributed and centralized H ∞ controllers are designed for a proof-of-concept 37-segment system model. In our proposed mirror design, the segments are dynamically coupled through a uniform support structure, which is modeled using the finite element method. In addition, the segments have the coupled control objective of maintaining the overall mirror shape to allow the highest possible image resolution. A spatially-invariant distributed model is obtained by using a finite element model of the 7-segment system. The resulting model is then used to synthesize a spatially-invariant distributed controller, and is expanded to obtain the 37-segment system by interconnecting the distributed model in a honeycomb-like pattern. The simulation results of the distributed controller is presented and compared with the results from the centralized H ∞ controller applied to the 37-segment model. It is shown that both centralized and spatially-invariant distributed controllers satisfy the imaging performance requirements. © 2011 Elsevier Ltd. All rights reserved. DA - 2012/01/17 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ed7ce156-3c7e-4982-bdaa-5f50773e9ebc ER - TY - CHAP TI - Preface AU - Lockwood, D. J. AU - Mascher, P. T2 - ECS Meeting Abstracts: 221st ECS Meeting T2 - ECS Transactions; no. Volume 45, Issue 5 T3 - 2nd International Symposium on Nanoscale Luminescent Materials - 221st ECS Meeting, May 6-10, 2012, Seattle, WA, USA SN - 1938-5862 SN - 9781566779579 DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 29672663-e8f8-4afa-8314-5b9e106e22c4 ER - TY - CHAP TI - Preface AU - Taylor, E. J. AU - Bock, C. AU - Inman, M. AU - Malek, K. T2 - ECS Meeting Abstracts: Honolulu PRiME 2012 T2 - ECS Transactions; no. Volume 50, Issue 23 T3 - Symposium on Contemporary Issues and Case Studies in Electrochemical Innovation - 222nd ECS Meeting/PRiME 2012, October 7-12, 2012, Honolulu, HI SN - 1938-5862 SN - 9781607684114 DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8305b430-672c-41c0-86ee-f8beca9711dd ER - TY - CHAP TI - Preface AU - Bock, C. AU - Leddy, J. T2 - ECS Meeting Abstracts: 220th ECS Meeting T2 - ECS Transactions; no. Volume 41, Issue 31 T3 - 1st Electrochemical Energy Summit, E2S 2011 - 220th ECS Meeting, October 10-12, 2011, Boston, MA, USA SN - 1938-5862 SN - 9781607683308 DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d8b2da95-29ab-4bec-ac71-5127c02387f1 ER - TY - JOUR TI - Characterization of individual multifunctional nanoobjects with restricted geometry DO - 10.1080/01411594.2012.722634 AU - Harnagea, C. AU - Azodi, M. AU - Nechache, R. AU - Cojocaru, C.-V. AU - Buscaglia, V. AU - Buscaglia, M. T. AU - Nanni, P. AU - Rosei, F. AU - Pignolet, A. T2 - Phase Transitions T3 - The Third COST (European Cooperation in Science and Technology) MP0904 WG Workshop, 23-24 April 2012 SN - 0141-1594 VL - 86 IS - 7 SP - 635 EP - 650 KW - Anisotropic nanostructures KW - Bismuth ferrites KW - Bismuth titanate KW - Electromechanical behavior KW - Ferroelectric nanostructures KW - Piezoelectric coefficient KW - Piezoresponse force microscopy KW - Restricted geometries KW - Anisotropy KW - Aspect ratio KW - Barium titanate KW - Bismuth KW - Ferroelectricity KW - Nanowires KW - Niobium oxide KW - Piezoelectricity KW - Scanning probe microscopy KW - Nanotubes AB - Anisotropic nanostructures such as nanowires (NWs)/nanotubes and nanometer-sized islands are the subject of intense research efforts due to several interesting phenomena observed to occur in confined geometries with a high aspect ratio and/or reduced size. Understanding and controlling the mechanical and electromechanical behaviors of these nanostructures are crucial for the practical implementation of such building blocks as active or passive components in nanodevices. Recent progresses toward the characterization of individual one-dimensional (NWs and nanotubes) and two-dimensional (islands) functional nanoscale objects of piezoelectric and ferroelectric (BaTiO3, Bi 4Ti3O12 (BiT), and NaNbO3) and multiferroics (BiFeO3 and Bi2FeCrO6 (BFCO)) are presented. These nanoobjects have been characterized using scanning probe microscopy-based techniques, combined with various modulation schemes for enhanced sensing capabilities. The most remarkable results include: ferroelectricity of NaNbO3/Nb2O5 nanotube heterostructures, negative piezoelectric coefficient in highly anisotropic BiT mesoscopic rods, and preservation of the multiferroic character of epitaxial BFCO nanoislands. © 2013 Copyright Taylor and Francis Group, LLC. DA - 2012/10/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ebd97702-4f0e-4f77-b288-032b5f3ba1cd ER - TY - JOUR TI - HMDB 3.0-The Human Metabolome Database in 2013 DO - 10.1093/nar/gks1065 AU - Wishart, David S. AU - Jewison, Timothy AU - Guo, An Chi AU - Wilson, Michael AU - Knox, Craig AU - Liu, Yifeng AU - Djoumbou, Yannick AU - Mandal, Rupasri AU - Aziat, Farid AU - Dong, Edison AU - Bouatra, Souhaila AU - Sinelnikov, Igor AU - Arndt, David AU - Xia, Jianguo AU - Liu, Philip AU - Yallou, Faizath AU - Bjorndahl, Trent AU - Perez-Pineiro, Rolando AU - Eisner, Roman AU - Allen, Felicity AU - Neveu, Vanessa AU - Greiner, Russ AU - Scalbert, Augustin T2 - Nucleic Acids Research SN - 0305-1048 VL - 41 IS - D1 SP - D801 EP - D807 AB - The Human Metabolome Database (HMDB) (www. hmdb.ca) is a resource dedicated to providing scientists with the most current and comprehensive coverage of the human metabolome. Since its first release in 2007, the HMDB has been used to facilitate research for nearly 1000 published studies in metabolomics, clinical biochemistry and systems biology. The most recent release of HMDB (version 3.0) has been significantly expanded and enhanced over the 2009 release (version 2.0). In particular, the number of annotated metabolite entries has grown from 6500 to more than 40000 (a 600% increase). This enormous expansion is a result of the inclusion of both 'detected' metabolites (those with measured concentrations or experimental confirmation of their existence) and 'expected' metabolites (those for which biochemical pathways are known or human intake/exposure is frequent but the compound has yet to be detected in the body). The latest release also has greatly increased the number of metabolites with biofluid or tissue concentration data, the number of compounds with reference spectra and the number of data fields per entry. In addition to this expansion in data quantity, new database visualization tools and new data content have been added or enhanced. These include better spectral viewing tools, more powerful chemical substructure searches, an improved chemical taxonomy and better, more interactive pathway maps. This article describes these enhancements to the HMDB, which was previously featured in the 2009 NAR Database Issue. (Note to referees, HMDB 3.0 will go live on 18 September 2012.) DA - 2012/11/17 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 696df74a-a27d-401f-a905-3a5b2cf4db60 ER - TY - JOUR TI - ECMDB: The E. coli Metabolome Database DO - 10.1093/nar/gks992 AU - Guo, An Chi AU - Jewison, Timothy AU - Wilson, Michael AU - Liu, Yifeng AU - Knox, Craig AU - Djoumbou, Yannick AU - Lo, Patrick AU - Mandal, Rupasri AU - Krishnamurthy, Ram AU - Wishart, David S. T2 - Nucleic Acids Research SN - 0305-1048 VL - 41 IS - D1 SP - D625 EP - D630 KW - bacterial enzyme KW - bacterial protein KW - amino acid sequence KW - bacterial gene KW - bacterial growth KW - bacterial metabolism KW - bacterial strain KW - bioinformatics KW - carbon nuclear magnetic resonance KW - chemical structure KW - Escherichia coli KW - factual database KW - gene sequence KW - mass spectrometry KW - metabolite KW - metabolome KW - molecular weight KW - proton nuclear magnetic resonance KW - Databases, Genetic KW - Escherichia coli K12 KW - Escherichia coli Proteins AB - The Escherichia coli Metabolome Database (ECMDB, http://www.ecmdb.ca) is a comprehensively annotated metabolomic database containing detailed information about the metabolome of E. coli (K-12). Modelled closely on the Human and Yeast Metabolome Databases, the ECMDB contains >2600 metabolites with links to ∼1500 different genes and proteins, including enzymes and transporters. The information in the ECMDB has been collected from dozens of textbooks, journal articles and electronic databases. Each metabolite entry in the ECMDB contains an average of 75 separate data fields, including comprehensive compound descriptions, names and synonyms, chemical taxonomy, compound structural and physicochemical data, bacterial growth conditions and substrates, reactions, pathway information, enzyme data, gene/protein sequence data and numerous hyperlinks to images, references and other public databases. The ECMDB also includes an extensive collection of intracellular metabolite concentration data compiled from our own work as well as other published metabolomic studies. This information is further supplemented with thousands of fully assigned reference nuclear magnetic resonance and mass spectrometry spectra obtained from pure E. coli metabolites that we (and others) have collected. Extensive searching, relational querying and data browsing tools are also provided that support text, chemical structure, spectral, molecular weight and gene/protein sequence queries. Because of E. coli's importance as a model organism for biologists and as a biofactory for industry, we believe this kind of database could have considerable appeal not only to metabolomics researchers but also to molecular biologists, systems biologists and individuals in the biotechnology industry. © The Author(s) 2012. DA - 2012/10/29 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0d7350c5-aea6-4ecb-a7eb-3fdd3509705f ER - TY - JOUR TI - Unearthing foundations of a cosmic cathedral: searching the stars for M33's halo DO - 10.1093/mnras/sts112 AU - Cockcroft, Robert AU - McConnachie, Alan W. AU - Harris, William E. AU - Ibata, Rodrigo AU - Irwin, Mike J. AU - Ferguson, Annette M. N. AU - Fardal, Mark A. AU - Babul, Arif AU - Chapman, Scott C. AU - Lewis, Geraint F. AU - Martin, Nicolas F. AU - Puzia, Thomas H. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 428 IS - 2 SP - 1248 EP - 1262 AB - We use data from the Pan-Andromeda Archaeological Survey to search for evidence of an extended halo component belonging to M33 (the Triangulum Galaxy).We identify a population of red giant branch (RGB) stars at large radii fromM33's disc whose connection to the recently discovered extended 'disc substructure' is ambiguous, and which may represent a 'bona fide' halo component. After first correcting for contamination from the Milky Way foreground population and misidentified background galaxies, we average the radial density of RGB candidate stars over circular annuli centred on the galaxy and away from the disc substructure. We find evidence of a low-luminosity, centrally concentrated component that is everywhere in our data fainter than μV ~ 33 mag arcsec-2. The scalelength of this feature is not well constrained by our data, but it appears to be of the order of rexp ~20 kpc; there isweak evidence to suggest that it is not azimuthally symmetric. Inspection of the overall colour-magnitude diagram for this region that specifically clips out the disc substructure reveals that this residual RGB population is consistent with an old population with a photometric metallicity of around [Fe/H] ~ -2 dex, but some residual contamination from the disc substructure appears to remain. We discuss the likelihood that our findings represent a bona fide halo in M33, rather than extended emission from the disc substructure. We interpret our findings in terms of an upper limit to M33's halo that is a fewper cent of its total luminosity, although its actual luminosity is likely much less. © 2012 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. DA - 2012/10/29 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 032083bd-9093-40c7-bb93-c101483779f3 ER - TY - JOUR TI - Generalised canonical-isokinetic ensemble: speeding up multiscale molecular dynamics and coupling with 3D molecular theory of solvation DO - 10.1080/08927022.2012.700486 AU - Omelyan, Igor AU - Kovalenko, Andriy T2 - Molecular Simulation SN - 0892-7022 VL - 39 IS - 1 SP - 25 EP - 48 KW - Alanine dipeptides KW - Computational time KW - Confined space KW - Conformational properties KW - Conformational space KW - Efficient sampling KW - Explicit solvents KW - Flexible model KW - Ligand molecules KW - Localisation KW - MD simulation KW - Molecular dynamics simulations KW - Molecular systems KW - Molecular theory of solvation KW - Multiple time step KW - Multiscales KW - Phase spaces KW - Picoseconds KW - Potential of mean force KW - Reference interaction site models KW - Solvation forces KW - Time step KW - Algorithms KW - Amino acids KW - Conformations KW - Phase space methods KW - Solvents KW - Three dimensional computer graphics AB - We have proposed a new canonical-isokinetic ensemble for efficient sampling of conformational space in molecular dynamics (MD) simulations which leads to the optimised isokinetic Nosé-Hoover (OIN) chain algorithm for atomic and molecular systems. We applied OIN to multiple time step (MTS) MD simulations of the rigid and flexible models of water to demonstrate its advantage over the standard canonical, isokinetic and canonical-isokinetic ensembles. With the stabilising effect of OIN thermostatting in MTS-MD, gigantic outer time steps up to picoseconds can be employed to accurately calculate equilibrium and conformational properties. Furthermore, we developed the atomic version of OIN for MTS-MD of a biomolecule in a solvent potential of mean force obtained at sequential MD steps by using the molecular theory of solvation, aka three-dimensional reference interaction site model with the Kovalenko-Hirata closure (3D-RISM-KH). The solvation forces are obtained analytically by converging the 3D-RISM-KH integral equations once per several OIN outer time steps, and are calculated in between by using solvation force-coordinate extrapolation (SFCE) in the subspace of previous successive solutions to 3D-RISM-KH. For illustration, we applied the multiscale OIN/SFCE/3D-RISM-KH algorithm to a fully flexible model of alanine dipeptide in aqueous solution. Although the computational rate of solvent sampling in OIN/SFCE/3D-RISM-KH is already 20 times faster than standard MD with explicit solvent, further substantial acceleration of sampling stems from making solute evolution steps in a statistically averaged potential of mean force obtained from 3D-RISM-KH. The latter efficiently samples the phase space for essential events with rare statistics such as exchange and localisation of solvent and ligand molecules in confined spaces, pockets and at binding sites of the solute macromolecule, as distinct from MD with explicit solvent which requires enormous computational time and number of steps in such cases. © 2013 Taylor & Francis Group, LLC. DA - 2012/08/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a35e694a-8e65-412d-9762-e095bb14a411 ER - TY - JOUR TI - Biomolecule delivery into canola protoplasts by centrifuging cells with microbubbles DO - 10.1016/j.febslet.2012.12.005 AU - He, Chuan AU - Gu, Quanrong AU - Huang, Min AU - Xing, James AU - Chen, Jie T2 - FEBS Letters SN - 0014-5793 VL - 587 IS - 3 SP - 285 EP - 290 KW - fluorescein isothiocyanate dextran KW - cell membrane KW - cell nucleus KW - cell transport KW - cell viability KW - cell wall KW - confocal microscopy KW - cytoplasm KW - flow cytometry KW - microbubble KW - protoplast KW - Biological Transport KW - Brassica KW - Cell Survival KW - Centrifugation KW - Cytological Techniques KW - Diffusion KW - Drug Delivery Systems KW - Fluorescein-5-isothiocyanate KW - Microbubbles KW - Protoplasts KW - Brassica napus var. napus AB - We have successfully delivered FITC and FITC-Dextran (70, 250 kDa) into canola protoplasts by centrifuging cells with different amounts of microbubbles at variable centrifuge speed. The efficiency is around 90%, while cell viability remains high. Confocal microscopy images show that both FITC and FITC-Dextran are scattered inside the cytoplasm and the cell nucleus. Pores are observed on canola protoplast cell membranes and cell walls when centrifuged with microbubbles, while the membrane of cells centrifuged alone remain intact and smooth. We hypothesize that the collision between the microbubbles and cells or the bursting of microbubbles are the main reasons for the formation of these pores. Biomaterials can diffuse into the cells once the pathway is created. © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved. DA - 2012/12/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 433c6466-34b6-4a4a-a97a-6acb3e9827b2 ER - TY - JOUR TI - Direct spectroscopic monitoring of conductance switching in polythiophene memory devices DO - 10.1016/j.electacta.2012.11.111 AU - Shoute, Lian C. T. AU - Wu, Yiliang AU - McCreery, Richard L. T2 - Electrochimica Acta SN - 0013-4686 VL - 110 SP - 437 EP - 445 KW - Solid state redox KW - Poly-thiophene KW - Atmospheric effects KW - Conductance switching KW - Mechanism of memory KW - Non-volatile memory KW - Nonvolatile memory devices KW - Raman spectroscopic KW - Spectroscopic monitoring KW - Electrolytic reduction KW - Molecular electronics KW - Nonvolatile storage KW - Organic polymers KW - Polarons KW - Polymer films KW - Redox reactions KW - Refractory metal compounds KW - Semiconductor doping AB - A large number of nonvolatile memory devices have been reported with both inorganic and organic components, and many of these involve changes in device resistance between a high conductivity "ON" state and a low conductivity "OFF" state. The mechanism of memory action in many of these devices is uncertain, and may be based on many phenomena, including redox reactions, metal filament formation, charge storage in "floating gates", and redistribution of oxide vacancies. We report here a Raman spectroscopic probe of organic polymer memory devices which permits direct monitoring of the doping state and conductivity of polythiophene in a 3-terminal device. The polymer conductance is controlled by voltage pulses between the source and gate electrodes in FET geometry, while the conductance state is read out by a separate circuit between source and drain. The conductance was directly correlated with the Raman determination of the density of polarons in the polymer film, which was shown to control both the "electroforming" process and the conductance switching in working memory devices. The polymer conductance change requires a redox counter-reaction at the gate electrode, and atmospheric effects on performance indicate that water and oxygen reduction are involved. The observations are consistent with a redox process between the gate and source electrodes which modulates the polaron concentration and source-drain conductivity. This mechanism provides a framework for optimization of the device by changing its composition and geometry, particularly the identity of the redox counter-reaction and control of ion mobility. © 2012 Elsevier Ltd. All rights reserved. DA - 2012/12/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c96c89b5-65c8-498a-9f00-3aa035c84727 ER - TY - JOUR TI - Flux engineering for indium tin oxide nanotree crystal alignment and height-dependent branch orientation DO - 10.1021/cg3013798 AU - Beaudry, Allan L. AU - Laforge, Joshua M. AU - Tucker, Ryan T. AU - Li, Peng AU - Taschuk, Michael T. AU - Brett, Michael J. T2 - Crystal Growth and Design SN - 1528-7483 VL - 13 IS - 1 SP - 212 EP - 219 KW - Azimuthal orientation KW - Biaxial textures KW - Competitive growth KW - Crystal texture KW - Dynamic controls KW - Glancing Angle Deposition KW - Growth surfaces KW - In-plane orientation KW - Indium tin oxide KW - Nanotrees KW - Oriented structure KW - Out-of-plane KW - Pole figure KW - Preferential orientation KW - Substrate rotation KW - Vapor fluxes KW - Vapor-liquid-solid growth KW - Alignment KW - Indium compounds KW - Nanowires KW - Vapors KW - X-ray diffraction KW - Crystal orientation AB - Single-crystal indium tin oxide (ITO) nanotrees with engineered trunk and branch orientations are grown using a recently reported technique combining vapor-liquid-solid growth and glancing angle deposition (VLS-GLAD). In this work, three unique capabilities of VLS-GLAD are demonstrated for the first time: (i) nanotrees are aligned without epitaxy, (ii) branches can be placed on select faces of the nanotree trunk, and (iii) branch orientation can be modified along the height of nanotrees. VLS-GLAD uses a collimated obliquely incident vapor flux to place material on desired growth surfaces, resulting in preferential branch growth on the sides of the nanotree trunk exposed to the flux at the time of nucleation. Dynamic control of the azimuthal orientation of the flux relative to a growing nanotree enables the preferential orientation of branches to be modulated along the height of the nanotree, which we have demonstrated with both continuous and discrete substrate rotation schemes. An electron diffraction investigation confirms that the nanotrees can be considered as a single crystal, with continuity of the crystal structure across the trunk-branch interface. Crystal texture of the films is characterized by X-ray diffraction pole figures. By limiting the flux to discrete positions, the films develop both out-of-plane and in-plane crystal alignment (biaxial texture). We interpret the in-plane orientation as the result of competitive growth, which leads to evolutionary selection of similarly oriented structures. Control over in-plane nanotree crystal alignment and height-dependent branch orientation should increase the achievable complexity in three-dimensional nanowire architectures. © 2012 American Chemical Society. DA - 2012/12/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4fd1c8ce-6b49-4d09-9c0b-e85570c7c00c ER - TY - JOUR TI - Label-free impedimetric immunosensor for ultrasensitive detection of cancer marker Murine double minute 2 in brain tissue DO - 10.1016/j.bios.2012.07.049 AU - Elshafey, Reda AU - Tlili, Chaker AU - Abulrob, Abedelnasser AU - Tavares, Ana C. AU - Zourob, Mohammed T2 - Biosensors and Bioelectronics SN - 0956-5663 VL - 39 IS - 1 SP - 220 EP - 225 KW - MDM2; Cancer biomarker; Brain tissue; Cysteamine; Immunosensor; 1,4-phenylene diisothiocyanate; Electrochemical impedance spectroscopy AB - The detection of cancer biomarkers is as important tool for the diagnosis and prognosis of cancer such as brain cancer. Murine double minute 2 (MDM2) has been widely studied as prognostic marker for brain tumor. Here we describe development of a new sensitive label free impedimetric immunosensor for the detection of MDM2 based on cysteamine self assembled monolayers on a clean polycrystalline Au electrode surface. The amine-modified electrodes were further functionalized with antibody using homobifunctional 1,4-phenylene diisothiocyanate (PDITC) linker. The assembly processes of the immunosensor had been monitored with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques using Fe(CN)6^3-/4- solution as redox probe. The impedance changes upon binding of MDM2 protein to the sensor surface was utilized for the detection of MDM2. The increase in relative electron-transfer resistance (ΔR/R0%) values was linearly proportional to the concentration of tumor marker MDM2 in the wide dynamic range of 1pg/ml-1μg/ml. The limit of detection was 0.29pg/ml in phosphate buffer saline (PBS) and 1.3pg/ml in mouse brain tissue homogenate, respectively. The immunosensor showed a good performance in comparison with ELISA for the analysis of the MDM2 in the cancerous mouse brain tissue homogenates. Moreover, the immunosensor had a good selectivity against epidermal growth factor receptor (EGFR) protein, long-storage stability and reproducibility. It might be become a promising assay for clinical diagnosis and early detection of tumors. © 2012 Elsevier B.V.. DA - 2012/08/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : df0e875a-2bce-4845-b369-b19ccbadd98e ER - TY - JOUR TI - Millimeter emission structure in the first alma image of the AU Mic debris disk DO - 10.1088/2041-8205/762/2/L21 AU - MacGregor, Meredith A. AU - Wilner, David .J. AU - Rosenfeld, Katherine A. AU - Andrews, Sean M. AU - Matthews, Brenda AU - Hughes, A. Meredith AU - Booth, Mark AU - Chiang, Eugene AU - Graham, James R. AU - Kalas, Paul AU - Kennedy, Grant AU - Sibthorpe, Bruce T2 - The Astrophysical Journal Letters SN - 2041-8205 VL - 762 IS - 2 SP - L21 AB - We present 1.3 mm ALMA Cycle 0 observations of the edge-on debris disk around the nearby, ∼10 Myr old, M-type star AU Mic. These observations obtain 0.″6 (6 AU) resolution and reveal two distinct emission components: (1) the previously known dust belt that extends to a radius of 40 AU and (2) a newly recognized central peak that remains unresolved. The cold dust belt of mass ∼1 MMoon is resolved in the radial direction with a rising emission profile that peaks sharply at the location of the outer edge of the "birth ring" of planetesimals hypothesized to explain the midplane scattered light gradients. No significant asymmetries are discerned in the structure or position of this dust belt. The central peak identified in the ALMA image is ∼6 times brighter than the stellar photosphere, which indicates an additional emission process in the inner regions of the system. Emission from a stellar corona or activity may contribute, but the observations show no signs of temporal variations characteristic of radio-wave flares. We suggest that this central component may be dominated by dust emission from an inner planetesimal belt of mass ∼0.01 MMoon, consistent with a lack of emission shortward of 25 μm and a location ≲3 AU from the star. Future millimeter observations can test this assertion, as an inner dust belt should be readily separated from the central star at higher angular resolution. © 2013. The American Astronomical Society. All rights reserved. DA - 2012/12/17 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ee0d4c32-8831-41cd-b8ab-ca745d743f07 ER - TY - CHAP TI - Semantic distance measures with distributional profiles of coarse-grained concepts DO - 10.1007/978-3-642-22613-7_4 AU - Hirst, Graeme AU - Mohammad, Saif T2 - Modeling, Learning, and Processing of Text Technological Data Structures T2 - Studies in Computational Intelligence; no. 370 SN - 1860-949X SN - 9783642226120 SP - 61 EP - 79 AB - Although semantic distance measures are applied to words in textual tasks such as building lexical chains, semantic distance is really a property of concepts, not words. After discussing the limitations of measures based solely on lexical resources such as WordNet or solely on distributional data from text corpora, we present a hybrid measure of semantic distance based on distributional profiles of concepts that we infer from corpora. We use only a very coarse-grained inventory of concepts - each category of a published thesaurus is taken as a single concept - and yet we obtain results on basic semantic-distance tasks that are better than those of methods that use only distributional data and are generally as good as those that use fine-grained WordNet-based measures. Because the measure is based on naturally occurring text, it is able to find word pairs that stand in non-classical relationships not found in WordNet. It can be applied cross-lingually, using a thesaurus in one language to measure semantic distance between words in another. In addition, we show the use of the method in determining the degree of antonymy of word pairs. DA - 2012/01/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e9cbbcab-c192-4cab-8ec7-f869c70b7fca ER - TY - JOUR TI - Plasma actuation control of boundary layer flashback in lean premixed combustor DO - 10.1115/GT2012-68224 AU - Versailles, Philippe AU - Chishty, Wajid Ali AU - Vo, Huu Duc T2 - Proceedings of the ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. Volume 2: Combustion, Fuels and Emissions, Parts A and B T3 - ASME Turbo Expo 2012: Turbine Technical Conference and Exposition, GT 2012, June 11-15, 2012, Copenhagen, Denmark SN - 9780791844687 SP - 133 EP - 142 KW - Dielectric barrier discharges KW - Emissions reduction KW - Equimolar mixtures KW - Equivalence ratios KW - Lean premixed combustors KW - Natural gas-air mixture KW - Novel applications KW - Premixed combustion KW - Boundary layers KW - Combustion KW - Combustion chambers KW - Combustors KW - Emission control KW - Exhibitions KW - Fuels KW - Mixtures KW - Natural gas KW - Gas turbines AB - Dry low emissions premixed combustion systems have the ability to give larger NOx emissions reduction in comparison to diffusion type of combustors. However, these systems are prone to flashback because the fuel and oxidizers are mixed upstream of the combustion chamber. This is particularly true for premixed systems burning high-reactivity fuels due to their higher flame speed. Flashback is undesirable in gas turbines because it leads to overheating and failure of fuel nozzles and premixing sections. Recently, a novel application of Plasma Actuation through non-thermal Dielectric Barrier Discharge has been shown to significantly delay flashback in the core flow along the axis of the premixer. Building on this successful endeavour, efforts were directed to prove the effectiveness of the control method in situations where flashback was triggered in the boundary layer. Results show that the current application delays the occurrence of flashback in the boundary layer of the premixer to higher equivalence ratios. Improvements in the combustor operability margin of 10 to 14% when burning natural gas-air mixtures, and of about 3.5% when replacing the fuel by an equimolar mixture of natural gas and hydrogen, were achieved. It was found that the proposed application of plasma actuation is even more efficient in preventing flashback in the boundary layer than in the core flow. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8b11dd9e-1f2d-4f4e-b418-b93ff66aa96f ER - TY - JOUR TI - Erosion resistance of titania co-doped yttria stabilized zirconia DO - 10.1115/GT2012-68172 AU - O'Brien, Adam AU - Huang, Xiao AU - Yang, Q. T2 - Proceedings of the ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. Volume 5: Manufacturing Materials and Metallurgy; Marine; Microturbines and Small Turbomachinery; Supercritical CO2 Power Cycles T3 - ASME Turbo Expo 2012: Turbine Technical Conference and Exposition, GT 2012, June 11-15, 2012, Copenhagen, Denmark SN - 9780791844717 SP - 61 EP - 69 KW - Abrasive particles KW - Erosion resistance KW - Failure mechanism KW - High-temperature sintering KW - Impingement angle KW - Thermal barrier coating (TBCs) KW - Thermal insulation capabilities KW - Yttria-stabilized zirconias (YSZ) KW - Brittle fracture KW - Exhibitions KW - Gas turbines KW - Hardness KW - Plasma spraying KW - Thermal barrier coatings KW - Thermal conductivity KW - Titanium dioxide KW - Yttria stabilized zirconia KW - Zirconia KW - Erosion AB - The standard yttria-stabilized zirconia (YSZ) has been used as thermal barrier coatings (TBCs) in the hot sections of gas turbine engines for several decades. To achieve further improvement to the thermal insulation capability of current TBCs, doping of alternative oxides to zirconia or co-doping of oxides to YSZ has been employed. In our previous study, it has been shown that doping of 7YSZ with titania (TiO2) reduces thermal conductivity of 7YSZ substantially. As TBCs are susceptible to various failure mechanisms, in this study the erosion resistance of TiYSZ at high impingement speed and angle is evaluated along with measurements of hardness (H) and elastic modulus (E). Specimens with 5 different TiO2 doping amounts (5%, 7.5%, 10%, 12.5% and 15%) are fabricated using plasma spraying and high temperature sintering. The erosion test results show that sample with 5% TiO2 (5TiYSZ) suffers the most erosion damage at high impingement angle due to brittle fracture while 10-15TiYSZ samples exhibit less brittle erosion damage which leads to lower erosion rates under the same test condition. When comparing the erosion rates (defined as the loss of sample mass per mass unit of abrasive particles) to the hardness values, they were found to follow the same trend. The addition of TiO2 (10-15 wt%) had the effect of reducing the erosion rate of 7YSZ at high impingement angle. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ca28176b-fff8-49f3-87a7-50e6f8c45e9a ER - TY - JOUR TI - Evaluation of the impact of alternative fuel use on the emissions and performance of a service-exposed T56 engine DO - 10.1115/GT2012-69978 AU - Chalmers, Jennifer L. Y. AU - Davison, Craig R. AU - Chishty, Wajid A. AU - Bird, Jeff W. AU - Chan, Tak AU - Barton, Peter AU - Dagenais, Rod AU - Pham, Vinh AU - Poitras, Pierre T2 - Proceedings of the ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. Volume 1: Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels; Controls, Diagnostics and Instrumentation T3 - ASME Turbo Expo 2012: Turbine Technical Conference and Exposition, GT 2012, June 11-15, 2012, Copenhagen, Denmark SN - 978-0-7918-4467-0 SP - 425 EP - 435 KW - Borescope inspection KW - Combustion characteristics KW - Emissions monitoring KW - Engine performance KW - Flight instrumentations KW - Operational requirements KW - Performance and emissions KW - Vibration characteristics KW - Alternative fuels KW - Engines KW - Exhibitions KW - Gas turbines KW - Durability AB - Alternative fuel sources are becoming an operational reality; these fuels have the potential to reduce emissions, improve combustion characteristics and to increase fuel supply security. A test with a T56 turboprop engine was performed to demonstrate that a CHEFA/JP8 (Camelina Hydroprocessed Ester and Fatty Acids and standard JP8) fuel blend would meet operational requirements. The primary test objective was to assess whether a fuel change had an immediate impact on the engine condition, performance, emissions or vibration characteristics. This paper presents test results comparing engine performance with JP8 and a 50/50 blend of JP8 and CHEFA. Comparison runs were conducted before and after a 20 hour ground durability test with the CHEFA fuel blend. A nearly time-expired, nacelle-dressed T56 on an outdoor test stand was tested. The engine was equipped with minimallyintrusive non-standard pressure, temperature and emissions monitoring equipment, and a field vibration assessment suite in addition to the standard flight instrumentation. This paper discusses the test plan, data acquisition methods, results and data repeatability. The performance and emissions results are compared to the changes predicted theoretically from the fuel properties. Observations from the borescope inspections before, during and after the 20 hour durability test are also presented. The lessons learned in this test could be applied to future fuel or process-change tests, and the results provide a performance baseline for engine health assessment. Copyright © 2012 by Her Majesty the Queen in Right of Canada DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5c4ffbf5-acb3-4e1a-b78d-02ab18f7aec1 ER - TY - JOUR TI - Morphology control and nanoscale patterning of small molecule organic thin films DO - 10.1117/12.922659 AU - Van Dijken, Jaron G. AU - Wu, Nathanael L.-W. AU - Fleischauer, Michael D. AU - Buriak, Jillian M. AU - Brett, Michael J. T2 - Organic Photonics V T2 - Proceedings of SPIE; 8435 T3 - Organic Photonics V, April 16-18, 2012, Brussels SN - 0277-786X SN - 9780819491275 SP - 84350R KW - Additional control KW - Column dimensions KW - Columnar arrays KW - Columnar morphology KW - Device fabrications KW - Donor layers KW - Film evolution KW - Glancing Angle Deposition KW - Glancing angle deposition technique KW - Metalphthalocyanines KW - Morphology control KW - Motion techniques KW - Nano-structuring KW - Nanoscale patterning KW - Organic photovoltaic devices KW - Organic photovoltaics KW - Organic thin films KW - Patterned ITO KW - Seed spacing KW - Small molecules KW - Surface patterning KW - Vertical posts KW - Zinc phthalocyanines KW - Block copolymers KW - Lithography KW - Morphology KW - Photovoltaic effects KW - Platinum KW - Silicon oxides KW - Surfaces KW - Thin films KW - Zinc compounds KW - Vapor deposition AB - We present methods for nanostructuring organic thin films for organic photovoltaic (OPV) devices. Using the glancing angle deposition (GLAD) technique, we fabricate a variety of columnar morphologies of metal phthalocyanine (MPc) materials that can be used as structured donor layers in OPV devices. We leverage this capability with block copolymer surface patterning techniques to achieve perfectly periodic columnar arrays while providing additional control over column dimensions, spacing, and density. Our investigation employs hexagonal seed patterns of platinum on silicon and we vary the seed spacing between 40 nm and 60 nm. We find that pattern resemblance begins to fade when the film thickness exceeds the seed spacing. We compare the film evolution between vertical post and slanted post morphologies, and use advanced substrate motion techniques to constrain column diameters. We conclude by addressing the compatibility of surface patterning with device fabrication. Patterned ITO surfaces and SiO 2 seed patterns are shown. DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 53922a22-5080-41ed-b8d3-528cbf82d1c8 ER - TY - JOUR TI - Statistical-mechanical, molecular theory of boundary conditions for liquid flow at nanostructured surfaces and in confined geometries DO - 10.1016/j.proeng.2012.08.425 AU - Kovalenko, A. T2 - Procedia Engineering T3 - Euromembrane Conference 2012, September 23-27, 2012, Westminster, London SN - 1877-7058 VL - 44 SP - 386 EP - 387 DA - 2012/11/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b0c3bc67-ff2f-402a-a304-cbaf9487a152 ER - TY - JOUR TI - Multiple regression analysis of the impact of track geometry on wheel-rail forces DO - 10.1115/JRC2012-74120 AU - Huang, W. AU - Liu, Y. AU - Preston-Thomas, J. T2 - 2012 Joint Rail Conference, JRC 2012 T3 - 2012 Joint Rail Conference, JRC 2012, 17 April 2012 through 19 April 2012, Philadelphia, PA SN - 9780791844656 SP - 245 EP - 253 AB - One of the fundamental keys to improving track safety standards is to establish a strong correlation between track geometry variations and wheel-rail force parameters that are indicators of vehicle-track safety performance. In this study, wheel-rail forces were collected during field tests of a loaded lumber car and an empty tank car. Computer models of the two tested freight cars were built, and the models were calibrated using field test results. The computer models were then used to evaluate the impact of varying track geometry parameters on track safety using the maximum single wheel L/V ratio, maximum truck side L/V ratio, and minimum vertical wheel load ratio. It was confirmed again that the correlations between these force parameters and any individual geometry parameter were weak. With further investigation, it was found that much better correlation can be achieved using multiple regression techniques to define each wheel-rail force parameter as a function of all track geometry parameters combined together. Expressions of the maximum truck side L/V ratio, maximum single wheel L/V ratio, and minimum vertical wheel load ratio were obtained as functions of curvature, cross level, alignment, gauge, and cant deficiency using multiple regression analysis. Copyright © 2012 by ASME. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 38f9e2a2-7fe4-41e6-a67f-a51153eaea44 ER - TY - JOUR TI - Genetic characterization of Escherichia coli O157:H7 strains isolated from the one-humped camel (Camelus dromedarius) by using microarray DNA technology DO - 10.1007/s12033-011-9466-7 AU - Salehi, T.Z. AU - Tonelli, A. AU - Mazza, A. AU - Staji, H. AU - Badagliacca, P. AU - Tamai, I.A. AU - Jamshidi, R. AU - Harel, J. AU - Lelli, R. AU - Masson, L. T2 - Molecular Biotechnology SN - 1073-6085 VL - 51 IS - 3 SP - 283 EP - 288 KW - bacterial DNA KW - virulence factor KW - animal KW - animal disease KW - article KW - bacterial gene KW - camel KW - classification KW - DNA microarray KW - Escherichia coli infection KW - Escherichia coli O157 KW - feces KW - genetics KW - isolation and purification KW - methodology KW - microbiology KW - Animals KW - Camels KW - DNA, Bacterial KW - Escherichia coli Infections KW - Escherichia coli O157 KW - Feces KW - Genes, Bacterial KW - Oligonucleotide Array Sequence Analysis KW - Virulence Factors AB - From the Camelidae family members, several serotypes of Escherichia coli (E. coli) have recently been isolated from diarrhoeic and non-diarrhoeic faecal samples. To date Shiga toxin-producing E. coli (STEC) strains have never been typed in one-humped camel (Camelus dromedarius). In the present study, two E. coli O157:H7 strains isolated from sick dromedaries were investigated. Virulence gene profiles were determined using a custom E. coli virulence DNA microarray, composed of 70-mer oligonucleotide probes targeting 264 virulence or related genes of known E. coli pathotypes. Both strains displayed positive hybridization signals for the Locus of enterocyte effacement (LEE) gene probes (ler, eae, espA, espB, tir genes), two Shiga toxin probes (stx1 and stx2), the O157 O-antigen specific probe, various virulence plasmid (pO157) probes like katP in addition to other accessory virulence genes characterized in STEC. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4d30fb53-d158-4ad1-be72-48771b0fd1ba ER - TY - JOUR TI - Load monitoring of aerospace structures using micro-electro-mechanical systems (MEMS) DO - 10.1115/SMASIS2012-8109 AU - Martinez, M. AU - Rocha, B. AU - Li, M. AU - Shi, G. AU - Beltempo, A. AU - Rutledge, R. AU - Yanishevsky, M. T2 - ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, SMASIS 2012 T3 - ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, SMASIS 2012, 19 September 2012 through 21 September 2012, Stone Mountain, GA SN - 9780791845097 VL - 1 SP - 799 EP - 805 AB - The National Research Council of Canada has developed Structural Health Monitoring (SHM) test platforms for load and damage monitoring, sensor system testing and validation. One of the SHM platform consists of two 2.25 meter long, simple cantilever aluminium beams that provide a perfect scenario for evaluating the capability of a load monitoring system to measure bending, torsion and shear loads. In addition to static and quasi-static loading procedures, these structures can be fatigue loaded using a realistic aircraft usage spectrum while SHM and load monitoring systems are assessed for their performance and accuracy. In this study, Micro-Electro-Mechanical Systems (MEMS), consisting of triads of gyroscopes, accelerometers and magnetometers, were used to compute changes in angles at discrete stations along the structure. A Least Squares based algorithm was developed for polynomial fitting of the different data obtained from the MEMS installed in several spatial locations of the structure. The angles obtained from the MEMS sensors were fitted with a second, third and/or fourth order degree polynomial surface, enabling the calculation of displacements at every point. The use of a novel Kalman filter architecture was evaluated for an accurate angle and subsequent displacement estimation. The outputs of the newly developed algorithms were then compared to the displacements obtained from the Linear Variable Displacement Transducers (LVDT) connected to the structures. The determination of the best Least Squares based polynomial fit order enabled the application of derivative operators with enough accuracy to permit the calculation of strains along the structure. The calculated strain values were subsequently compared to the measurements obtained from reference strain gauges installed at different locations on the structure. This new approach for load monitoring was able to provide accurate estimates of applied strains and loads. Copyright © 2012 by Her Majesty The Queen in Right of Canada. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 556be5e0-f0b4-43a5-ba39-bcf8d173358d ER - TY - JOUR TI - Sorption of CO2/CH4 mixtures in PIM-1 and PTMSP membrjanes: Experimental data at 35°C and modeling DO - 10.1016/j.proeng.2012.08.559 AU - Vopicka, O. AU - De Angelis, M.G. AU - Sarti, G.C. AU - Du, N. AU - Li, N. AU - Guiver, M.D. T2 - Procedia Engineering T3 - Euromembrane Conference 2012, 23 September 2012 through 27 September 2012, Westminster, London SN - 1877-7058 VL - 44 SP - 758 EP - 759 DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : add48b3d-6580-4a4b-a170-db9de5c7a5fe ER - TY - JOUR TI - The effect of motion on wind tunnel drag measurement for athletes DO - 10.1016/j.proeng.2012.04.012 AU - D'Auteuil, A. AU - Larose, G.L. AU - Zan, S.J. T2 - Procedia Engineering T3 - 9th Conference of the International Sports Engineering Association, ISEA 2012, 9 July 2012 through 13 July 2012, Lowell, MA SN - 1877-7058 VL - 34 SP - 62 EP - 67 AB - To optimize the reduction of the drag area coefficient of a speed skater, mannequins in static positions wearing suits were tested in the NRC 2m × 3m Wind Tunnel to find the lowest drag for a given range of speeds. The results obtained from this study can only be interpreted and applied to a speed skater if the aerodynamic drag coefficient is not affected significantly by the motion of the skater. It has been assumed that, for a representative cadence or frequency of oscillation of a speed skater lower than 1 Hz which is representative of the motion in a race, the aerodynamics could be considered quasi-stationary. The quasi-steady state is defined by the flow that developed around the body and the wake both governing the aerodynamic drag compared to the contribution of the low frequency of oscillation of the body. To verify this hypothesis and to determine to what extent the quasi-steady assumption is valid for a human body in a speed skating position, a study was carried out in a wind tunnel using a moving life-size mannequin. A mechanism was devised so that a mannequin in a sidepush position could be oscillated to mimic the sinusoidal path of a speed skater. The amplitude of motion was kept constant and the frequencies of oscillation and wind speeds were changed to cover the equivalent of 500 m to 10,000 m races. The experiments have revealed that the variations of the drag area coefficient with wind speed were similar for static positions and for cases where the mannequin was oscillating at frequencies lower than 0.67 Hz or for a period of rotation of 1.5 s. The drag reduction occurred at the same wind speeds for the static and dynamic cases. This paper presents details of the experiments and a summary of the main findings. © 2012 Published by Elsevier Ltd. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 11a94962-2c65-44e7-996a-3c7254c894ab ER - TY - JOUR TI - A molecular simulation study of Pt stability on oxidized carbon nanoparticles DO - 10.1016/j.jpowsour.2012.08.014 AU - Ban, Shuai AU - Malek, Kourosh AU - Huang, Cheng T2 - Journal of Power Sources SN - 0378-7753 VL - 221 SP - 21 EP - 27 KW - Molecular dynamics; Carbon black; Pt degradation; Fuel cells AB - Molecular simulation is used to model the structural change of carbon nanoparticles in terms of total mass loss during the oxidation process. The density changes as well as simulation snapshots suggest a location-dependent gasification, particularly taking place in the core of the carbon particles. A graphitic shell structure of degraded carbon particles obtained from our simulations is in agreement with experimental observations. In addition, the shrinkage of graphitic crystallites near the carbon surface leads to the formation of micropores, the volume of which increases with the oxidation level. On the basis of this carbon model, the stability of Pt nanoparticles is investigated for various temperatures and roughnesses of the carbon surface. Simulation results show that migration and coalescence of Pt particles indeed occur, but at a low rate. In particular, detachment and transport of small Pt clusters were observed from simulation snapshots, supporting the argument that the transport of molecular Pt species occurs on carbon surface. The thermal activation plays a key role in the deformation of the Pt crystal structure. During simulations, both the size and surface of Pt particles increase at elevated temperature, i.e. 600 °C. However, only a few of the surface Pt atoms may contribute to the catalytic performance due to their site-dependent reactivity. DA - 2012/08/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 33135d69-bf5d-4c58-89ba-7955207575f3 ER - TY - JOUR TI - Pulsed laser deposition of vanadium-doped manganese oxide thin films for supercapacitor applications DO - 10.1016/j.jpowsour.2012.11.067 AU - Yang, Dongfang T2 - Journal of Power Sources SN - 0378-7753 VL - 228 SP - 89 EP - 96 KW - Electrochemical capacitor; Supercapacitor; Pulsed laser deposition; Vanadium doping; Manganese oxides; Thin films AB - Thin films of vanadium-doped crystalline Mn2O3 and amorphous MnOx have been grown by the pulsed laser deposition (PLD) process on silicon wafer and stainless steel substrates at different substrate temperatures and oxygen gas pressures. It was found that V-doping level as low as 3.2 atm. % can transform the crystal structure of a crystalline Mn 2O3 film into a crystalline MnO2 film. V-doping (up to 10 atm. %) has significantly lowered the specific capacitance of the crystalline Mn2O3 films. However, V-doped amorphous MnOx films did significantly increase the specific capacitance at high CV scan rate as compared with the un-doped MnOx films and the specific capacitance of V-doped amorphous films increased linearly with the V atomic percentage. At high scan rate of 100 mV s-¹, 9.7 atm. % V-doped MnOx film reached a high specific capacitance value of 95 F g-#185; indicating that V-doped amorphous MnOx is good candidate active materials for high energy supercapacitors. The results prove that elemental doping can significantly change the electrochemical properties of MnOx films. DA - 2012/11/29 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 51954392-ddc2-41af-b7ff-d3213152295d ER - TY - JOUR TI - Troubleshooting the rabbit ferric chloride-induced arterial model of thrombosis to assess in vivo efficacy of antithrombotic drugs DO - 10.1016/j.vascn.2012.11.003 AU - Couture, L. AU - Richer, L. P. AU - Mercier, M. AU - Hélie, C. AU - Lehoux, D. AU - Hossain, S. M. T2 - Journal of Pharmacological and Toxicological Methods SN - 1056-8719 VL - 67 IS - 2 SP - 91 EP - 97 KW - Antithrombotic drug; Blood flow; Ferric chloride; Methods; Rabbit; Time to occlusion AB - Introduction: The FeCl3-induced arterial model of thrombosis is one of the most widely used animal models to assess arterial efficacy of new antithrombotic drug candidates. This model is well-established in rodents but in a less extent in the rabbit. In this work, we present a methodology for a rabbit FeCl3-induced arterial model of thrombosis derived from our troubleshooting which allows the generation of reliable efficacy data for new antithrombotic drug candidates. Methods: Rabbits were administered with heparin 4.5U/kg/min, argatroban 10μg/kg/min or saline by intravenous infusion. The blood flow was monitored using a Doppler flow probe. The time from the application of FeCl3 to the recorded zero blood flow was defined as the time to occlusion, with a maximum recording time of 60min post-FeCl3 application. After 30min of infusion, thrombosis was induced by wrapping a FeCl3-saturated filter paper around the carotid artery caudal to the flow probe. Animals were subject to exclusion criteria based on the visual aspect of the artery FeCl3-induced injury and based on changes in blood flow upon FeCl3 application. Results: Following the application of FeCl3, a mean time to occlusion for saline, heparin and argatroban of 24.3±1.8, 52.5±4.8 and 53.5±4.5min was obtained, respectively. Mean time to occlusion for heparin and argatroban administered groups was significantly different when compared to the saline-treated group (p<0.05). These results for the test compounds represent approximately 80% of the maximum possible prolongation. Discussion: The rabbit FeCl3-induced arterial model of thrombosis presented in this paper derived from our troubleshooting is sensitive and reproducible for the generation of accurate and reliable efficacy data in the assessment of new antithrombotic agents in preclinical drug development. © 2012. DA - 2012/12/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6aab74ff-b697-4cbb-abad-cc3b9a7d521e ER - TY - JOUR TI - Dynamics of brain structure and cognitive function in the Alzheimer's disease neuroimaging initiative DO - 10.1136/jnnp-2012-303579 AU - Song, Xiaowei AU - Mitnitski, Arnold AU - Zhang, Ningnannan AU - Chen, Wei AU - Rockwood, Kenneth T2 - Journal of Neurology, Neurosurgery and Psychiatry SN - 0022-3050 VL - 84 IS - 1 SP - 71 EP - 78 AB - Background: On average, cognition declines as people age, but improvement can also occur. Objective: To evaluate the dynamics of age-related changes in brain structure and cognitive function in patients with mild Alzheimer's disease (AD) and mild cognitive impairment (MCI) and in healthy control (HC) older adults. Methods: High-resolution 3-Tesla MRI and clinical data were obtained from the Alzheimer's Disease Neuroimaging Initiative in 187 subjects (a cohort aged 55-91 years; AD=43, MCI=84, HC=60). At 24 months, 151 people had clinical and 128 had MRI follow-up. Brain structure was assessed using the Medial Temporal Atrophy Scale (MTAS) and the Brain Atrophy and Lesion Index (BALI). Cognition was assessed using the Mini-Mental State Examination (MMSE) and the Alzheimer Disease Assessment Scale-cognitive subscale (ADAS-cog). Responsiveness was tested. Changes were analysed using a multistate dynamic model, adjusted for age, gender, ApoE4 genotype and vascular risk factors. Results: Over 2 years, decline in brain structure and cognition predominated, each showing detectable effect sizes (Cohen's d=0.33 for MTAS, 0.32 for BALI, 0.41 for MMSE, 0.38 for ADAS-cog; standard response mean=0.71, 0.69, 0.50 and 0.47, respectively). Structural improvement was observed (10.2% in BALI and 0.8% in MTAS), as was cognitive improvement (23.2% MMSE, 27.2% ADAS-cog). Most people (66.7%) whose BALI score improved also improved in either the MMSE or ADAS-cog. No patient with MCI whose MTAS or BALI improved converted to AD. Conclusions: Despite average decline in brain structure, improvement was observed and related to cognition and MCI-AD conversion. Ageing-related brain changes reflect a dynamic process. DA - 2012/11/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 539576ae-e0f8-4931-a9d2-8ad7dc573ae5 ER - TY - JOUR TI - Evaluation of systematic shifts for the 88Sr+ 445-THz reference transition at the 10-17 level using the NRC next generation ion trap system DO - 10.1109/CPEM.2012.6250904 AU - Madej, A. A. AU - Dubé, P. AU - Zhou, Z. AU - Bernard, J. E. T2 - 2012 Conference on Precision Electromagnetic Measurements T3 - 2012 Conference on Precision Electromagnetic Measurements (CPEM 2012), July 1-6, 2012, Washington, DC, USA SN - 978-1-4673-0442-9 SN - 978-1-4673-0439-9 SN - 978-1-4673-0441-2 SP - 266 EP - 267 KW - Clocks KW - frequency control KW - ions KW - lasers KW - precision mesurements KW - spectroscopy KW - start effect KW - strontium AB - We describe receent progress in the establishment of a versatile and reliable optical frequency standard whose performance in evaluated accuracy and stability exceeds that of the current realization of the SI second. The 445-THz reference transition in a single, trapped, and laser cooled ion of 88Sr⁺ suspended using a miniature RF endcap trap system in the new trap have been reduced to the 2 x 10⁻¹⁷ level for each of the scalar Stak shifts and the time dilation shifts. Studies indicate that such shifts remain stable over several hours. An identical trap system was constructed to evaluate the electrode heating effects of the shift will be limited by the current knowledge of the scalar polarizabilities of the upper and lower states of the reference transition, currently at the 2 x 10⁻¹⁷ level. DA - 2012/07/06 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b3acf826-ade8-4b35-bba7-45661713048b ER - TY - JOUR TI - Exchange, correlation, and the effective mass m* of electrons in two-dimensional layers calculated via a DFT-based classical map DO - 10.1002/qua.24273 AU - Dharma-Wardana, M. W. C. T2 - International Journal of Quantum Chemistry SN - 0020-7608 VL - 113 IS - 6 SP - 873 EP - 879 KW - 2-D systems KW - 2D layer KW - Classical fluids KW - Correlation energy KW - DFT-based KW - Effective mass KW - Electron fluid KW - Electron systems KW - Electronic wave functions KW - Energy functionals KW - Exchange-correlations KW - Fermi-liquid properties KW - Finite temperatures KW - G factors KW - Hartree-fock KW - Interacting electrons KW - Kohn shams KW - Landau-fermi liquids KW - Pair distribution functions KW - Pauli exclusion KW - Quantum Monte Carlo simulations KW - Quasi particles KW - D region KW - Density functional theory KW - Intelligent systems KW - Kinetics KW - Thermodynamics AB - Density functional theory uses the electron density n(r), instead of the electronic wavefunction. We side-step the kinetic energy functional by constructing a thermodynamically equivalent classical map (CM). A classical Coulomb fluid whose zeroth-order pair-distribution function (PDF) g 0(r) that agrees with the quantum g0, and interacting via a "Pauli exclusion potential" reproduces the thermodynamics of the electron fluid, when the classical-fluid temperature Tcf is chosen optimally. This Tcf is chosen so that the correlation energy of the classical fluid is the Kohn-Sham correlation energy. Then, the PDFs of the classical fluid closely agree with the PDFs of the two-dimensional (2D) and 3D uniform electron systems. Can we calculate sensitive Fermi-liquid properties (e.g., quasiparticle mass m*, Landé g-factor) of interacting electrons via this CM? Given the wide interest in the effective mass m* of electrons in 2D layers, we chose the 2D system for this study. Analytical and numerical results are used to define a partially regularized m* valid to logarithmic accuracy in the sense of Landau for the Hartree-Fock (H-F) approximation. The resulting H-F m* decreases linearly with the electron-disk radius rs. The m* including correlation is calculated via a physically transparent formula. This uses the CM of the 2D PDF and its finite-T exchange-correlation free energy Fxc(T). Our results for m* fall well within the results from recent quantum Monte-Carlo simulations at T = 0, and other theoretical and experimental results. DA - 2012/07/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b63bfdec-87a1-48a1-8aaf-fe6feef76b6a ER - TY - JOUR TI - Smart gold nanoparticles enhance killing effect on cancer cells DO - 10.3892/ijo.2012.1721 AU - Song, Kun AU - Xu, Peng AU - Meng, Yongde AU - Geng, Feng AU - Li, Jie AU - Li, Zhao AU - Xing, James AU - Chen, Jie AU - Kong, Beihua T2 - International Journal of Oncology SN - 1019-6439 VL - 42 IS - 2 SP - 597 EP - 608 KW - glucose capped gold nanoparticle KW - radiosensitizing agent KW - unclassified drug KW - antineoplastic activity KW - apoptosis KW - cancer radiotherapy KW - cell killing KW - cellular distribution KW - comparative study KW - controlled study KW - cytoplasm KW - drug effect KW - drug uptake KW - endocytosis KW - flow cytometry KW - human cell KW - internalization KW - nick end labeling KW - radiosensitization KW - transmission electron microscopy KW - X irradiation AB - The present study explored the cellular uptake dynamics, the subcellular location and the internalization mechanisms of gold nanoparticles (GNPs) and glucose-capped GNPs (Glu-GNPs). The cancer radiotherapy-enhancing effects of GNPs were also evaluated. We synthesized the GNPs and Glu-GNPs by the seeding technique. The effects on cellular uptake and the radiosensitizing effect induced by GNPs and Glu-GNPs at lower doses were investigated using two human cancer cell lines (HeLa and MCF-7). The intracellular location of the nanoparticles was analyzed by transmission electron microscopy (TEM). Analysis of cellular apoptosis following GNP-based radiotherapy was performed by flow cytometry and TUNEL assay. Cancer cells took up more Glu-GNPs than naked GNPs and the uptake curve showed size- and cell-dependent uptake. GNPs were mainly located in the cytoplasm and endocytosis is the mechanism behind the internalization of GNPs and Glu-GNPs. Lower doses of GNPs and Glu-GNPs still enhanced the killing effect using X-ray irradiation, although the apoptotic rate was not altered. The results presented in this study provide evidence that Glu-GNPs may have a bright future in tumor-targeted diagnosis and treatment. DA - 2012/11/29 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9125de9d-04b0-49e1-b9f1-cf62b9b38f90 ER - TY - JOUR TI - Alzheimer's disease: An update of the roles of receptors, astrocytes and primary cilia (Review) DO - 10.3892/ijmm.2012.1162 AU - Armato, Ubaldo AU - Chakravarthy, Balu AU - Pacchiana, Raffaella AU - Whitfield, James F. T2 - International Journal of Molecular Medicine SN - 1107-3756 VL - 31 IS - 1 SP - 3 EP - 10 KW - amyloid beta protein KW - amyloid beta-peptides KW - calcium sensing receptor KW - glial fibrillary acidic protein KW - guanosine triphosphate cyclohydrolase I KW - inducible nitric oxide synthase KW - neurotrophin receptor p75 KW - protein Patched KW - protein tyrosine kinase A KW - smoothened protein KW - somatomedin C receptor KW - sonic hedgehog protein KW - tetrahydrobiopterin KW - vasculotropin A KW - cell damage KW - ciliary body KW - dentate gyrus KW - enzyme activity KW - granule cell KW - intracellular signaling KW - mild cognitive impairment KW - nerve cell necrosis KW - nerve cell primary cilia KW - neural stem cell KW - neuroblastoma cell KW - protein expression KW - protein phosphorylation KW - signal transduction KW - cell Death KW - dentate gyrus KW - hippocampus KW - neurogenesis KW - neurons KW - receptor, nerve growth factor KW - receptors, calcium-sensing KW - signal transduction AB - The pathophysiological mechanisms underlying the onset and inexorable progression of the late-onset form of Alzheimer's disease (AD) are still the object of controversy. This review takes stock of some most recent advancements of this field concerning the complex roles played by the amyloid-β (Aβ)-binding p75 neurotrophin receptor (p75NTR) and calcium-sensing receptor (CaSR) and by the primary cilia in AD. Apart from their physiological roles, p75NTR is more intensely expressed in the hippocampus of human AD brains and Aβ-bound p75NTR triggers cell death, whereas Aβ-bound CaSR signalling induces the de novo synthesis and release of nitric oxide (NO), vascular endothelial growth factor (VEGF)-A and Aβ peptides (Aβs), particularly on the part of normal adult human astrocytes. The latter effect could significantly increase the pool of Aβ-and NO-producing nerve cells favouring the progressive spread of a self-sustaining and self-reinforcing 'infectious' mechanism of neural and vascular (i.e. blood-brain barrier) cell damage. Interestingly, primary cilia concentrate p75NTR receptors in their membranes and are abnormally structured/damaged in transgenic (Tg) AD-model mice, which could impact on the adult neurogenesis occurring in the dentate gyrus's subgranular zone (SGZ) that is necessary for new memory encoding, thereby favouring typical AD cognitive decline. Altogether, these findings may pave the way to novel therapeutic approaches to AD, particularly in its mild cognitive impairment (MCI) and pre-MCI stages of development. DA - 2012/10/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : dc261f57-494a-4c4b-a290-9647232dd286 ER - TY - JOUR TI - Curvature analysis to differentiate magnetic sources for geologic mapping DO - 10.1111/j.1365-2478.2012.01111.x AU - Lee, Madeline AU - Morris, William AU - Leblanc, George AU - Harris, Jeff T2 - Geophysical Prospecting SN - 0016-8025 VL - 61 IS - Supplement 1 SP - 572 EP - 585 KW - Magnetics; Potential Field; Signal Processing; Data Processing AB - Curvature of a surface is typically applied in seismic data interpretation; however this work outlines its application to a potential field, specifically aeromagnetic data. The curvature of a magnetic grid (from point data) is calculated by fitting a quadratic surface within a moving window at each grid node. The overall and directional curvatures calculated within this window provide insight into the geometry of the magnetic grid surface and causative sources. Curvature analysis is an in-depth study of both qualitative (graphically) and quantitative (statistically) approaches. This analysis involved the calculation of full, profile and plan curvatures. The magnitude, sign and relative ratios enable the user to define source location and geometry and also discriminate source type; for example, differentiation between a fault and normal polarity dyke. The reliability of the analysis is refined when a priori geological knowledge is available and basic statistics are considered. By allotting a weighting scheme to various statistical populations (e.g., standard deviation), increased detail is extracted on the different lithologies and structures represented by the data set. Furthermore, the curvature's behaviour is analogous to derivative calculation (vertical, horizontal and tilt) by producing a zero value at the source edge and either a local maxima or minima over the source. Application prior to semi-automated methods may help identify correct indices necessary for identification of magnetic sources. Curvature analysis is successfully applied to an aeromagnetic data set over the 2.6-1.85 Ga Paleoproterozoic Wopmay orogen, Northwest Territories, Canada. This area has undergone regional and local-scale faulting and is host to multiple generations of dyke swarms. As the area has been extensively mapped, this data set proved to be an ideal test site. DA - 2012/11/23 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a19dc21c-9d6c-4ceb-b745-2176a246d464 ER - TY - JOUR TI - A comparative life cycle assessment of diesel and compressed natural gas powered refuse collection vehicles in a Canadian city DO - 10.1016/j.enpol.2012.09.064 AU - Rose, Lars AU - Hussain, Mohammed AU - Ahmed, Syed AU - Malek, Kourosh AU - Costanzo, Robert AU - Kjeang, Erik T2 - Energy Policy SN - 0301-4215 VL - 52 SP - 453 EP - 461 KW - Life cycle assessment (LCA); Compressed natural gas (CNG); Refuse collection vehicle (RCV) AB - Consumers and organizations worldwide are searching for low-carbon alternatives to conventional gasoline and diesel vehicles to reduce greenhouse gas (GHG) emissions and their impact on the environment. A comprehensive technique used to estimate overall cost and environmental impact of vehicles is known as life cycle assessment (LCA). In this article, a comparative LCA of diesel and compressed natural gas (CNG) powered heavy duty refuse collection vehicles (RCVs) is conducted. The analysis utilizes real-time operational data obtained from the City of Surrey in British Columbia, Canada. The impact of the two alternative vehicles is assessed from various points in their life. No net gain in energy use is found when a diesel powered RCV is replaced by a CNG powered RCV. However, significant reductions (approximately 24% CO2-equivalent) in GHG and criteria air contaminant (CAC) emissions are obtained. Moreover, fuel cost estimations based on 2011 price levels and a 5-year lifetime for both RCVs reveal that considerable cost savings may be achieved by switching to CNG vehicles. Thus, CNG RCVs are not only favorable in terms of reduced climate change impact but also cost effective compared to conventional diesel RCVs, and provide a viable and realistic near-term strategy for cities and municipalities to reduce GHG emissions. DA - 2012/10/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2c735c3c-5cd0-4768-aa10-fb839b4d09f6 ER - TY - JOUR TI - Charging and discharging electrochemical supercapacitors in the presence of both parallel leakage process and electrochemical decomposition of solvent DO - 10.1016/j.electacta.2012.12.056 AU - Ban, Shuai AU - Zhang, Jiujun AU - Zhang, Lei AU - Tsay, Ken AU - Song, Datong AU - Zou, Xinfu T2 - Electrochimica Acta SN - 0013-4686 VL - 90 SP - 542 EP - 549 KW - Electrochemical supercapacitor; Charge and discharge; Parallel leakage; Self-discharging; Solvent decomposition AB - Simple models for electrochemical supercapacitors are developed to describe the charge-discharge behaviors in the presence of both voltage-independent parallel leakage process and electrochemical decomposition of solvent. The models are validated by experimental data collected using a symmetric two-electrode test cell with carbon powder as the electrode layer material and stainless steel as the current collector. DA - 2012/12/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 26af5b5d-4b33-4f20-a2a1-97751fb02ae9 ER - TY - JOUR TI - Crowdsourcing a word-emotion association lexicon DO - 10.1111/j.1467-8640.2012.00460.x AU - Mohammad, Saif M. AU - Turney, Peter D. T2 - Computational Intelligence SN - 0824-7935 VL - 29 IS - 3 SP - 436 EP - 465 KW - affect KW - Crowdsourcing KW - emotion lexicon KW - emotions KW - Mechanical turks KW - polarity lexicon KW - Semantic orientation KW - Sentiment analysis KW - Artificial intelligence KW - Computational methods KW - Semantics AB - Even though considerable attention has been given to the polarity of words (positive and negative) and the creation of large polarity lexicons, research in emotion analysis has had to rely on limited and small emotion lexicons. In this paper, we show how the combined strength and wisdom of the crowds can be used to generate a large, high-quality, word-emotion and word-polarity association lexicon quickly and inexpensively. We enumerate the challenges in emotion annotation in a crowdsourcing scenario and propose solutions to address them. Most notably, in addition to questions about emotions associated with terms, we show how the inclusion of a word choice question can discourage malicious data entry, help to identify instances where the annotator may not be familiar with the target term (allowing us to reject such annotations), and help to obtain annotations at sense level (rather than at word level). We conducted experiments on how to formulate the emotion-annotation questions, and show that asking if a term is associated with an emotion leads to markedly higher interannotator agreement than that obtained by asking if a term evokes an emotion. DA - 2012/09/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4d626836-c350-421f-9775-f549024097fd ER - TY - JOUR TI - Ecotoxicity of xanthene dyes and a non-chlorinated bisphenol in soil DO - 10.1016/j.chemosphere.2012.10.096 AU - Ritchie, Ellyn E. AU - Princz, Juliska I. AU - Robidoux, Pierre Yves AU - Scroggins, Rick P. T2 - Chemosphere SN - 0045-6535 VL - 90 IS - 7 SP - 2129 EP - 2135 AB - Soil eco-toxicity testing was conducted in support of Canada's Chemical Management Plan (CMP) to fill data gaps for organic chemicals known to primarily partition to soil, and of which the persistence and inherent toxicity are uncertain. Two compounds representative of specific classes of chemicals: non-chlorinated bisphenols containing an -OH group (4,4'-methylenebis(2,6-di-tert-butylphenol (Binox)) and xanthene dyes (2',4',5',7'-tetrabromo-4,5,6,7-tetrachloro-3',6'-dihydroxy-, disodium salt (Phloxine B), 2',4',5',7'-tetrabromofluorescein (TBF), 4',5'-dibromofluorescein (DBF), and 4,5,6,7-tetrachlorofluorescein (TCF)) were evaluated. The effect of these substances on plant growth (Elymus lanceolatus and Trifolium pratense) and soil invertebrate survival and reproduction (Folsomia candida and Eisenia andrei) were assessed using a field-collected sandy soil. Binox was persistent throughout testing (up to 63d) with an average recovery of 77±2.9% at test end. Binox was not toxic to plants (IC50s>1076mgkg-¹) or E. andrei (IC50s>2651mgkg-¹); however, a significant reduction in F. candida adult survival and reproduction (IC50=89 (44-149) mgkg-¹) was evident. Phloxine B was also persistent throughout testing, with an average recovery of 82±3.0% at test end. Phloxine B was significantly more toxic than Binox, with significant reductions in plant root growth (IC50s≥11mgkg-¹) and invertebrate reproduction (IC50s≥22mgkg-¹). DBF toxicity was not significantly different from that of Phloxine B for plant root growth (IC50s≥30mgkg-¹), but was significantly less toxic for shoot growth (IC50s≥1758mgkg-¹), and invertebrate adult survival (IC50s≥2291mgkg-¹) and reproduction (IC50s≥451mgkg-¹). A comparison between all four xanthene dyes was completed using F. candida, with the degree of toxicity in the order of Phloxine B≥TBF~DBF>TCF. The results from these studies will contribute to data gaps for poorly understood chemicals (and chemical groupings) under review for environmental risk assessments, and will aid in the validation of model predictions used to characterize the fate and effects of these substances in soil environments. DA - 2012/12/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 58f7756b-8dff-48cc-9d73-b0b5e8e7d3d4 ER - TY - JOUR TI - Quantification of strain through linear dichroism in the Si 1s edge X-ray absorption spectra of strained Si1-xGex thin films DO - 10.1016/j.apsusc.2012.11.012 AU - Cao, W. AU - Masnadi, M. AU - Eger, S. AU - Martinson, M. AU - Xiao, Q.-F. AU - Hu, Y.-F. AU - Baribeau, J.-M. AU - Woicik, J. C. AU - Hitchcock, A. P. AU - Urquhart, S. G. T2 - Applied Surface Science SN - 0169-4332 VL - 265 SP - 358 EP - 362 KW - Angle dependence KW - Angle-dependent KW - Compressive strain KW - High spatial resolution KW - Linear dichroism KW - NEXAFS KW - Si(1 0 0) KW - Silicon-germanium alloys KW - Strain metrology KW - Strain-dependent KW - Strained-Si KW - Total electron yield KW - X-ray absorption spectrum KW - X-ray spectromicroscopy KW - Absorption spectra KW - Dichroism KW - Epitaxial growth KW - Germanium KW - Germanium alloys KW - Raman spectroscopy KW - Strain KW - Thin films KW - X ray absorption spectroscopy KW - Silicon AB - We have quantitatively measured the angle dependence in the Silicon 1s X-ray absorption spectra of strained Si1-xGex thin films prepared by epitaxial growth on Si(1 0 0) substrates, through surface sensitive total electron yield detection. The linear dichroism difference extracted from these angle dependent X-ray absorption spectra is proportional to the degree of strain, as measured separately by Raman spectroscopy. This quantitative relationship provides a means to measure the compressive strain in Si 1-xGex thin films. This strain-dependent X-ray absorption spectroscopy has the potential to realize a semiconductor strain metrology through high spatial resolution X-ray spectromicroscopy. DA - 2012/11/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 406092d1-80c0-4a84-85c5-19e1f747326e ER - TY - JOUR TI - Ti4O7 supported Ru@Pt core-shell catalyst for CO-tolerance in PEM fuel cell hydrogen oxidation reaction DO - 10.1016/j.apenergy.2012.10.017 AU - Zhang, Lei AU - Kim, Jenny AU - Zhang, Jiujun AU - Nan, Feihong AU - Gauquelin, Nicolas AU - Botton, Gianluigi A. AU - He, Ping AU - Bashyam, Rajesh AU - Knights, Shanna T2 - Applied Energy SN - 0306-2619 VL - 103 SP - 507 EP - 513 KW - Alloy catalyst KW - Carbon monoxide tolerance KW - Core shell structure KW - Electrochemical measurements KW - Energy dispersive X-ray spectrometry KW - High resolution KW - High-angle annular dark fields KW - Hydrogen oxidation reaction KW - Reducing atmosphere KW - Ruthenium precursors KW - Scanning transmission electron microscopy KW - TiO KW - Electrocatalysts KW - Electron energy loss spectroscopy KW - Platinum alloys KW - Proton exchange membrane fuel cells (PEMFC) KW - Shells (structures) KW - Titanium dioxide KW - X ray diffraction KW - Ruthenium alloys KW - catalysis KW - catalyst KW - electrochemical method KW - irradiance KW - microwave radiation KW - pyrolysis AB - A new method is developed for synthesizing Ti4O7 supported Ru@Pt core-shell catalyst (Ru@Pt/Ti4O7) through pyrolysis followed by microwave irradiation. The purpose is to improve the Ru durability of PtRu from core-shell structure and strong bonding to Ti4O7 oxide. In this method, the first step is to co-reduce the mixture of ruthenium precursor and TiO2 in a H2 reducing atmosphere under heat-treatment to obtain a Ru core on Ti4O7 support, and the second step is to create a shell of platinum via microwave irradiation. Energy dispersive X-ray spectrometry, X-ray Diffraction, High-resolution Scanning Transmission Electron Microscopy with the high-angle annular dark-field method and Electron Energy-Loss Spectroscopy are used to demonstrate that this catalyst with larger particles has a core-shell structure with a Ru core and a Pt shell. Electrochemical measurements show Ru@Pt/Ti4O7 catalyst has a higher CO-tolerance capability than that of PtRu/C alloy catalyst. DA - 2012/11/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 731129f8-091c-43a0-96b3-79cbab219259 ER - TY - JOUR TI - Biological and physicochemical wastewater treatment processes reduce the prevalence of virulent Escherichia coli DO - 10.1128/AEM.02789-12 AU - Frigon, Dominic AU - Biswal, Basanta Kumar AU - Mazza, Alberto AU - Masson, Luke AU - Gehr, Ronald T2 - Applied and Environmental Microbiology SN - 0099-2240 VL - 79 IS - 3 SP - 835 EP - 844 KW - After-treatment KW - DNA micro-array KW - E. coli KW - Freshwater environments KW - Pathogenic bacterium KW - Pathogenic E. coli KW - Quinolones KW - Resistance genes KW - Treatment process KW - Virulence factors KW - Virulence gene KW - Wastewater treatment plants KW - Wastewater treatment process KW - Activated sludge process KW - Effluents KW - Pathogens KW - microbial activity KW - physicochemical property KW - genetics KW - genotype KW - isolation and purification KW - microarray analysis KW - water management KW - DNA, Bacterial KW - Genotype KW - Microarray Analysis KW - Waste Water KW - Water Purification AB - Effluents discharged from wastewater treatment plants are possible sources of pathogenic bacteria, including Escherichia coli, in the freshwater environment, and determining the possible selection of pathogens is important. This study evaluated the impact of activated sludge and physicochemical wastewater treatment processes on the prevalence of potentially virulent E. coli. A total of 719 E. coli isolates collected from four municipal plants in Québec before and after treatment were characterized by using a customized DNA microarray to determine the impact of treatment processes on the frequency of specific pathotypes and virulence genes. The percentages of potentially pathogenic E. coli isolates in the plant influents varied between 26 and 51%, and in the effluents, the percentages were 14 to 31%, for a reduction observed at all plants ranging between 14 and 45%. Pathotypes associated with extraintestinal pathogenic E. coli (ExPEC) were the most abundant at three of the four plants and represented 24% of all isolates, while intestinal pathogenic E. coli pathotypes (IPEC) represented 10% of the isolates. At the plant where ExPEC isolates were not the most abundant, a large number of isolates were classified as both ExPEC and IPEC; overall, 6% of the isolates were classified in both groups, with the majority being from the same plant. The reduction of the proportion of pathogenic E. coli could not be explained by the preferential loss of one virulence gene or one type of virulence factor; however, the quinolone resistance gene (qnrS) appears to enhance the loss of virulence genes, suggesting a mechanism involving the loss of pathogenicity islands. DA - 2012/11/16 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7450b834-891f-4dd6-8023-ebef3e1d176b ER - TY - JOUR TI - Low-pressure synthesis and characterization of hydrogen-filled ice Ic DO - 10.1002/anie.201208367 AU - Kumar, Rajnish AU - Klug, Dennis D. AU - Ratcliffe, Christopher I. AU - Tulk, Christopher A. AU - Ripmeester, John .A. T2 - Angewandte Chemie - International Edition SN - 1433-7851 VL - 52 IS - 5 SP - 1531 EP - 1534 KW - Amorphous ice KW - Clathrates KW - Cubic ice KW - Hydrogen storage materials KW - Low pressures KW - Hydrates KW - Loading KW - Vapors AB - A hydrogen storage material: When vapor-deposited amorphous ice is exposed to a low pressure (about 12 MPa) of hydrogen at 140 K a hydrogen-filled cubic ice results (see picture). Calculations suggest that this material has the potential for hydrogen storage with a capacity of 10 wt % hydrogen at full loading. DA - 2012/12/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6fb1e324-bc8d-4aa8-a1f8-35e7b6c9eb52 ER - TY - JOUR TI - Determination of trace elements in fluoropolymers after microwave-induced combustion DO - 10.1021/ac3029213 AU - Flores, Erico M. M. AU - Muller, Edson I. AU - Duarte, Fabio A. AU - Grinberg, Patricia AU - Sturgeon, Ralph E. T2 - Analytical Chemistry SN - 0003-2700 VL - 85 IS - 1 SP - 374 EP - 380 KW - Absorbing medium KW - Acid extraction KW - Analytes KW - Closed systems KW - Fluorinated ethylene propylene KW - Inductively-coupled KW - Microwave-assisted KW - Microwave-induced combustion KW - Residual carbon KW - Sample holders KW - Combustion KW - Inductively coupled plasma KW - Manganese KW - Mass spectrometry KW - Nitric acid KW - Quartz KW - Fluorine containing polymers KW - politef KW - silicon dioxide KW - microwave radiation KW - neutron KW - Mass Spectrometry KW - Microwaves KW - Neutrons KW - Nitric Acid KW - Polytetrafluoroethylene KW - Quartz KW - Trace Elements AB - An effective approach to the digestion of fluoropolymers for the determination of Ag, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, and Ni impurities has been developed using microwave-induced combustion (MIC) in closed quartz vessels pressurized with oxygen. Samples that were examined included the following: polytetrafluorethylene (PTFE); polytetrafluoroethylene with an additional modifier, perfluoropropylvinylether (PTFE-TFM); and fluorinated ethylene propylene (FEP). A quartz device was used as a sample holder, and the influence of the absorber solution was evaluated. Determination of trace elements was performed by inductively coupled plasma-optical emission and mass spectrometry. Neutron activation analysis (NAA) was used for validation purposes. Results were also compared to those obtained using microwave-assisted acid extraction in high-pressure closed systems. Dilute nitric acid (5 mol L-1), which was selected as the absorbing medium, was used to reflux the sample for 5 min after the combustion. Using these conditions, agreement for all analytes was better than 98% when compared to values determined by NAA. The residual carbon content in the digests was lower than 1%, illustrating the high efficiency of the method. Up to 8 samples could be digested within 30 min using MIC, providing a suitable throughput, taking into account the inertness of such samples. DA - 2012/11/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8990edfc-86d2-45e9-8d06-d198dae9f29e ER - TY - JOUR TI - Novel ethyl-derivatization approach for the determination of fluoride by headspace gas chromatography/mass spectrometry DO - 10.1021/ac302303r AU - Pagliano, Enea AU - Meija, Juris AU - Ding, Jianfu AU - Sturgeon, Ralph E. AU - D'Ulivo, Alessandro AU - Mester, Zoltán T2 - Analytical Chemistry SN - 0003-2700 VL - 85 IS - 2 SP - 877 EP - 881 KW - Adverse effect KW - Batch reactions KW - Certified reference materials KW - Closed vessels KW - Derivatizations KW - Fluoride ion KW - Gas chromatography/Mass spectrometry KW - Headspace gas chromatography KW - Headspaces KW - Limit of detection KW - Linear range KW - Non-volatile KW - One-step reactions KW - Standard addition KW - Tap water KW - Tetrachloroferrate KW - Chromatography KW - Iron compounds KW - Organic solvents KW - Seawater KW - Spectrometry AB - We report a novel derivatization chemistry for determination of fluoride based on the batch reaction of fluoride ions with triethyloxonium tetrachloroferrate(III) in a closed vessel to yield fluoroethane. Gaseous fluoroethane was readily separated from the matrix, sampled from the headspace, and determined by gas chromatography/mass spectrometry. The method was validated using rainwater certified reference material (IRMM CA408) and subsequently applied to the determination of fluoride in various matrixes, including tap water, seawater, and urine. An instrumental limit of detection of 3.2 μg/L with a linear range up to 50 mg/L was achieved. The proposed derivatization is a one-step reaction, requires no organic solvents, and is safe, as the derivatizing agent is nonvolatile. Determination of fluoride is affected by common fluoride-complexing agents, such as Al(III) and Fe(III). The effect of large amounts of these interferences was studied, and the adverse effect of these ions was eliminated by use of the method of standard additions. DA - 2012/12/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 09525e2a-5f5b-486b-8ef4-838601e78703 ER - TY - JOUR TI - Guest editorial: medical near infrared spectroscopy 35 years after the discovery DO - 10.1255/jnirs.982 AU - Ferrari, Marco AU - Norris, Karl H. AU - Sowa, Michael G. T2 - Journal of Near Infrared Spectroscopy SN - 0967-0335 VL - 20 IS - 1 SP - vii EP - ix DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1336b909-4738-47ee-b56b-e55fc8712d43 ER - TY - JOUR TI - New radio observations of the Moon at L band DO - 10.1088/1674-4527/12/9/010 AU - Zhang, Xi-Zheng AU - Gray, Andrew AU - Su, Yan AU - Li, Jun-Duo AU - Landecker, Tom AU - Zhang, Hong-Bo AU - Li, Chun-Lai T2 - Research in Astronomy and Astrophysics SN - 1674-4527 VL - 12 IS - 9 SP - 1297 EP - 1312 AB - We present results of new radio observations of the Moon at L band with the synthesis telescope of the Dominion Radio Astrophysical Observatory Synthesis Telescope. The resolution and temperature sensitivity of the observations are 159″ × 87″ and 1.7K, respectively. The main results are: (1) the lunar brightness temperature averaged over the whole disk is about 233 K while the average brightness temperature for the four quadrants are 228.1K (NE), 239.7K (NW), 233.9K (SW) and 228.8K (SE). The observations reveal large temperature and spatial variations on the Moon for the first time. The highest brightness temperature is about 257 K and it is located along the lunar equator, to the west. The total uncertainty is about 5% due to the absolute accuracy of the fluxes of the primary calibrators; (2) the total degree of polarization is about 6%. Both polarization intensity and degree of polarization increase from the disk's center to the limb, and the distribution of the degree of polarization along the limb is not uniform; (3) the new data are used to study the properties of regolith, such as dielectric constant and thickness distribution. The results show that the lunar regolith's thickness increases from the NW (mare area) to the SE (highland area) regions on the lunar surface. DA - 2012/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 098befea-13df-42ca-a44c-453d37690f04 ER - TY - JOUR TI - SSOS: A moving-object image search tool for asteroid precovery DO - 10.1086/666462 AU - Gwyn, Stephen D. J. AU - Hill, Norman AU - Kavelaars, J. J. T2 - Publications of the Astronomical Society of the Pacific SN - 0004-6280 VL - 124 IS - 916 SP - 579 EP - 585 AB - It is very difficult to find archival images of solar system objects. While regular archive searches can find images at a fixed location, they cannot find images of moving targets. Archival images have become increasingly useful to extragalactic and stellar astronomers the last few years, but until now, solar system researchers have been at a disadvantage in this respect. The Solar System Object Search (SSOS) at the Canadian Astronomy Data Centre allows users to search for images of moving objects. SSOS accepts as input either a list of observations, an object designation, a set of orbital elements, or a user-generated ephemeris for an object. It then searches for images containing that object over a range of dates. The user is then presented with a list of images containing that object from a variety of archives. Initially created to search the CFHT MegaCam archive, SSOS has been extended to other telescope archives, including Gemini, Subaru/SuprimeCam, HST, several ESO instruments, and the SDSS, for a total of 6.5 million images. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4d6749a7-1ecc-4482-b440-c85faf625966 ER - TY - JOUR TI - Observations, analysis, and spectroscopic classification of HO piscium: a bright shallow-contact binary with G- and M-type components DO - 10.1086/666748 AU - Samec, Ronald G. AU - Smith, Paul M. AU - Robb, Russell AU - Faulkner, Danny R. AU - Van Hamme, W. T2 - Publications of the Astronomical Society of the Pacific SN - 0004-6280 VL - 124 IS - 917 SP - 693 EP - 699 AB - We present a spectrum and a photometric analysis of the newly discovered, high-amplitude, solartype, eclipsing binary HO Piscium. A spectroscopic identification, a period study, q-search, and a simultaneous UBVR cI c light-curve solution are presented. The spectra and our photometric solution indicate that HO Psc is a W-typeWUMa shallow-contact (fill-out ~8%) binary system. The primary component has a G6V spectral type with an apparently precontact spectral type of M2V for the secondary component. The small fill-out indicates that the system has not yet achieved thermal contact and thus has recently come into physical contact. This may mean that this solar-type binary system has not attained its ~0:4 mass ratio via a long period of magnetic braking, as would normally be assumed. DA - 2012/06/28 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 332858eb-4ed9-4b7f-b6bc-42e0b849d334 ER - TY - JOUR TI - Probing the mass assembly of massive nearby galaxies with deep imaging DO - 10.1017/S174392131300536X AU - Duc, P.-A. AU - Cuillandre, J.-C. AU - Alatalo, K. AU - Blitz, L. AU - Bois, M. AU - Bournaud, F. AU - Bureau, M. AU - Cappellari, M. AU - Côté, P. AU - Davies, R. L. AU - Davis, T. A. AU - De Zeeuw, P. T. AU - Emsellem, E. AU - Ferrarese, L. AU - Ferriere, E. AU - Gwyn, S. AU - Khochfar, S. AU - Krajnovic, D. AU - Kuntschner, H. AU - Lablanche, P.-Y. AU - McDermid, R. M. AU - Michel-Dansac, L. AU - Morganti, R. AU - Naab, T. AU - Oosterloo, T. AU - Sarzi, M. AU - Scott, N. AU - Serra, P. AU - Weijmans, A. AU - Young, L. M. T2 - The intriguing life of massive galaxies T2 - Proceedings of the International Astronomical Union T3 - International Astronomical Union Symposium 295: The intriguing life of massive galaxies, August 27-31, 2012, Beijing, China SN - 1743-9213 SN - 9781107033849 SP - 358 EP - 361 AB - According to a popular scenario supported by numerical models, the mass assembly and growth of massive galaxies, in particular the Early-Type Galaxies (ETGs), is, below a redshift of 1, mainly due to the accretion of multiple gas-poor satellites. In order to get observational evidence of the role played by minor dry mergers, we are obtaining extremely deep optical images of a complete volume limited sample of nearby ETGs. These observations, done with the CFHT as part of the ATLAS3D, NGVS and MATLAS projects, reach a stunning 28.5 - 29 mag.arcsec-2 surface brightness limit in the g' band. They allow us to detect the relics of past collisions such as faint stellar tidal tails as well as the very extended stellar halos which keep the memory of the last episodes of galactic accretion. Images and preliminary results from this on-going survey are presented, in particular a possible correlation between the fine structure index (which parametrizes the amount of tidal perturbation) of the ETGs, their stellar mass, effective radius and gas content. DA - 2012/07/17 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bed0f7ef-93d9-4d2e-95a2-edec0e2b58d7 ER - TY - JOUR TI - Behaviour of fibre reinforced polymer-strengthened T-beams and slabs in fire DO - 10.1680/stbu.11.00014 AU - Adelzadeh, Masoud AU - Green, Mark F. AU - Bénichou, Noureddine T2 - Proceedings of the Institution of Civil Engineers: Structures and Buildings SN - 0965-0911 VL - 165 IS - 7 SP - 361 EP - 371 KW - Carbon fibre reinforced polymer KW - Fibre reinforced KW - Finite difference KW - Fire endurances KW - Fire engineering KW - Fire tests KW - Heat transfer model KW - Insulation system KW - Numerical results KW - Reinforced concrete member KW - Service loads KW - Standard fire KW - T beams KW - Carbon fibers KW - Concrete construction KW - Fiber reinforced plastics KW - Patient rehabilitation KW - Reinforced concrete KW - Flammability testing KW - concrete structure KW - experimental study KW - finite difference method KW - fire behavior KW - heat transfer KW - high temperature KW - insulation KW - numerical model KW - polymer KW - reinforced concrete KW - structural component KW - temperature effect AB - This paper presents experimental and numerical results of intermediate-scale and full-scale fire tests conducted on flexurally strengthened reinforced concrete members. Two full-scale reinforced concrete T-beams and two intermediate-scale slabs were strengthened in flexure with carbon fibre reinforced polymer sheets or plates and insulated with a layer of spray-on material. T-beams and slabs were then exposed to a standard fire. T-beams were loaded to their service load. Deflections and temperatures were measured during the tests. A numerical finite-difference/volume heat transfer model was used to simulate the temperature field inside the section. The validity of the numerical model was verified by comparing the predicted temperatures with those recorded during the fire test. Fire test results show that fire endurances of more than 4 h can be achieved using an appropriate insulation system. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 309a4977-ef9e-4a18-873f-de2653e53388 ER - TY - JOUR TI - Hydrodynamic impacts of tidal power lagoons in the Bay of Fundy AU - Cousineau, Julien AU - Nistor, Ioan AU - Cornett, Andrew T2 - Proceedings of the 33rd International Conference on Coastal Engineering 2012 T3 - 33rd International Conference on Coastal Engineering 2012, ICCE 2012, July 1-6, 2012, Santander, Spain SN - 9780989661119 SP - 3061 EP - 3075 KW - Bay of Fundy KW - Circulation patterns KW - Hydrodynamic impacts KW - Hydrodynamic model KW - Power generating systems KW - Reliable estimates KW - Renewable energies KW - Tidal lagoon KW - Coastal engineering KW - Energy resources KW - Hydraulic structures KW - Hydrodynamics KW - Numerical models KW - Ocean currents KW - Seawater KW - Tidal power KW - Tides KW - Water levels KW - Lakes AB - The Bay of Fundy (BoF) in eastern Canada has long been recognised as one of the world's premier locations for the development of tidal power generating systems, since it has some of the world's largest tidal ranges. Several proposals have been made in recent years to find economical ways to harness the power of these extremely high tides, including constructing one or more tidal power lagoons in the upper part of the Bay. The tidal power lagoon concept involves temporarily storing seawater behind an impoundment dike and generating power by gradually releasing the impounded seawater through conventional low-head hydroelectric turbines. A tidal power lagoon will inherently modify the tides and tidal currents in the vicinity of the lagoon, and possibly induce effects that may be felt throughout the entire BoF and Gulf of Maine. The nature of these hydrodynamic impacts will likely depend on the size of the tidal lagoon, its location, and its method of operation. It is important to have reliable estimates of these potential impacts, since any changes in tidal hydrodynamics caused by a tidal lagoon may upset ecosystems that are well adapted to existing conditions. The scale and character of the potential hydrodynamic impacts due to tidal power lagoons operating in the BoF have not been previously investigated. This paper presents the results of study in which a 2D (depth-averaged) hydrodynamic model based on the TELEMAC modelling system was developed and applied to analyze, predict, and quantify the potential changes in tidal hydrodynamics (water levels, tidal range, circulation patterns and tidal currents) throughout the Bay of Fundy and Gulf of Maine due to the presence of a single tidal lagoon and multiple lagoons operating at various locations in the upper BoF. The sensitivity to changes in lagoon type, size, location, the number of lagoons, and their operating mode was also investigated and established. The final purpose of this novel study is to assist with decisions concerning the development of the vast tidal energy resources available in the Bay of Fundy, Canada. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5e4bb343-c6c2-4b51-871d-a22762562b00 ER - TY - JOUR TI - A critical evaluation of turbulence modeling in a model combustor DO - 10.1115/GT2012-68414 AU - Jiang, Leiyong T2 - Proceedings of the ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. Volume 1: Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels; Controls, Diagnostics and Instrumentation T3 - ASME Turbo Expo 2012: Turbine Technical Conference and Exposition, GT 2012, June 11-15, 2012, Copenhagen, Denmark SN - 9780791844670 SP - 535 EP - 545 KW - Accurate prediction KW - Conjugate heat transfer KW - Critical evaluation KW - Diffusion flame combustors KW - Operating condition KW - Reynolds stress models KW - Second-moment closures KW - Turbulence kinetic energy KW - Exhibitions KW - Gas turbines KW - Kinetics KW - Turbulence models KW - Combustors AB - Based on the previous benchmark studies on combustion, scalar transfer and radiation models, a critical evaluation of turbulence models in a propane-air diffusion flame combustor with interior and exterior conjugate heat transfers has been performed. Results obtained from six turbulence models are presented and compared in detail with a comprehensive database obtained from a series of experimental measurements. It is found that the Reynolds stress model (RSM), a second moment closure, is superior over the five popular eddy-viscosity two-equation models. Although the main flow patterns are captured by all six turbulence models, only the RSM is able to successfully predict the lengths of both recirculation zones and give fairly accurate predictions for mean velocity, temperature, CO2 and CO mole fractions, as well as turbulence kinetic energy in the combustor chamber. In addition, the realizable k-ε (Rk-ε) model illustrates better performance than four other two-equation models and can provide comparable results to those from the RSM for the configuration and operating conditions considered in the present study. Copyright © 2012 by ASME. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3ec4d64b-9e8c-4642-a8cc-e1bd7cd15ef4 ER - TY - JOUR TI - Effects of scalloping on the mixing mechanisms of forced mixers with highly swirling core flow DO - 10.1115/GT2012-70081 AU - Wright, Alex AU - Lei, Zhijun AU - Mahallati, Ali AU - Cunningham, Mark AU - Militzer, Julio T2 - Proceedings of the ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. Volume 1: Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels; Controls, Diagnostics and Instrumentation T3 - ASME Turbo Expo 2012: Turbine Technical Conference and Exposition, GT 2012, 11 June 2012 through 15 June 2012, Copenhagen SN - 9780791844670 SP - 437 EP - 448 KW - Computational investigation KW - Inlet swirls KW - Lower pressures KW - Mixing mechanisms KW - Reduced pressure KW - Separation bubble KW - Suction surfaces KW - Swirl angles KW - Computer simulation KW - Exhibitions KW - Gas turbines KW - Mixing KW - Molluscs KW - Vortex flow KW - Mixers (machinery) AB - This paper presents a detailed experimental and computational investigation of the effects of scalloping on the mixing mechanisms of a scaled 12-lobe turbofan mixer. Scalloping was achieved by eliminating approximately 70% of the lobe sidewall area. Measurements were made downstream of the mixer in a co-annular wind tunnel and the simulations were carried out using an unstructured RANS solver, Numeca FINE/Hexa, with k-ω SST model. In the core flow, the swirl angle was varied from 0° to 30°. At high swirl angles, a three-dimensional separation bubble was formed on the lobe's suction surface penetration region and resulted in the generation of a vortex at the lobe valley. The valley vortex quickly dissipated downstream. Most of the swirl was removed by the lobes, but scalloping allowed residual swirl to persist downstream of the mixer. The interaction of the swirling flow and the vortices resulted in improved mixing rates for the scalloped mixer. Inlet swirl up to 10° provided improved mixing rates, reduced pressure loss and thrust loss for both mixers. High inlet swirl resulted in improved mixing but produced higher pressure and thrust losses as compared to the zero swirl case. At high swirl, the scalloped mixer resulted in better mixing and lower pressure losses than the unscalloped mixer, but at the expense of reduced thrust. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9e883250-4b17-4f36-8a5e-d6ccb2ee6d10 ER - TY - JOUR TI - Tribological behaviours of titanium nitride and chromium nitride based PVD coating systems DO - 10.1115/GT2012-68107 AU - Cai, F. AU - Huang, Xiao AU - Yang, Q. AU - Nagy, Doug T2 - Proceedings of the ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. Volume 5: Manufacturing Materials and Metallurgy; Marine; Microturbines and Small Turbomachinery; Supercritical CO2 Power Cycles T3 - ASME Turbo Expo 2012: Turbine Technical Conference and Exposition, GT 2012, June 11-15, 2012, Copenhagen, Denmark SN - 9780791844717 SP - 41 EP - 49 KW - Coating compositions KW - Coefficient of frictions KW - CrN-based coatings KW - Erosion resistance KW - Plasma enhanced magnetron sputtering KW - Specific wear rates KW - Tribological behaviour KW - Tribological properties KW - Amorphous films KW - Elastic moduli KW - Exhibitions KW - Friction KW - Gas turbines KW - Hardness KW - Microstructure KW - Protective coatings KW - Titanium nitride KW - Tribology KW - Erosion AB - This study investigates the effects of the deposition process and coating composition on microstructural and tribological properties of TiN and CrN based coating systems. Coatings were produced using various PVD based processes - electron beam (EB), cathodic arc (CA) and plasma enhanced magnetron sputtering (PEMS). All coated samples were evaluated for their composition, microstructure and surface morphology. Coating mechanical properties such as hardness, Young's modulus and coefficient of friction were also studied and related to their microstructures, wear and erosion resistances. It was found that hardness (H), Young's modulus (E) and coefficient of friction had impact on both wear and erosion rates. In particular, the H3/E2 ratio was inversely proportional to the specific wear rate. For erosion behaviour, higher H3/E2 ratios relate to lower erosion rates at low impingement angles; whereas higher H3/E2 ratios relate to higher erosion rates at high impingement angles. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c3defa80-d369-4dcf-9ba2-8d43f15c7bd0 ER - TY - JOUR TI - On advanced estimation techniques for exoplanet detection and characterization using ground-based coronagraphs DO - 10.1117/12.925099 AU - Lawson, Peter R. AU - Poyneer, Lisa AU - Barrett, Harrison AU - Frazin, Richard AU - Caucci, Luca AU - Devaney, Nicholas AU - Furenlid, Lars AU - Gładysz, Szymon AU - Guyon, Olivier AU - Krist, John AU - Maire, Jérôme AU - Marois, Christian AU - Mawet, Dimitri AU - Mouillet, David AU - Mugnier, Laurent AU - Pearson, Iain AU - Perrin, Marshall AU - Pueyo, Laurent AU - Savransky, Dmitry T2 - Adaptive Optics Systems III T2 - Proceedings of SPIE; 8447 T3 - Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491480 SP - 844722 KW - Coronagraphs KW - Data challenges KW - Detectability KW - Direct imaging KW - Earth-like planets KW - Estimation techniques KW - Exo-planets KW - Ground based KW - Hotelling observers KW - Ideal observers KW - Instrumentation KW - Jupiters KW - Localization rocs KW - Measurement Noise KW - Receiver operating characteristics KW - State of the art KW - Adaptive optics KW - Planets AB - The direct imaging of planets around nearby stars is exceedingly difficult. Only about 14 exoplanets have been imaged to date that have masses less than 13 times that of Jupiter. The next generation of planet-finding coronagraphs, including VLT-SPHERE, the Gemini Planet Imager, Palomar P1640, and Subaru HiCIAO have predicted contrast performance of roughly a thousand times less than would be needed to detect Earth-like planets. In this paper we review the state of the art in exoplanet imaging, most notably the method of Locally Optimized Combination of Images (LOCI), and we investigate the potential of improving the detectability of faint exoplanets through the use of advanced statistical methods based on the concepts of the ideal observer and the Hotelling observer. We propose a formal comparison of techniques using a blind data challenge with an evaluation of performance using the Receiver Operating Characteristic (ROC) and Localization ROC (LROC) curves. We place particular emphasis on the understanding and modeling of realistic sources of measurement noise in ground-based AO-corrected coronagraphs. The work reported in this paper is the result of interactions between the co-authors during a week-long workshop on exoplanet imaging that was held in Squaw Valley, California, in March of 2012. DA - 2012/09/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5e58d6be-a78a-47cf-aeda-dded0ede98f9 ER - TY - JOUR TI - Final opto-mechanical design of Raven, a MOAO science demonstrator for Subaru DO - 10.1117/12.927176 AU - Lardière, Olivier AU - Nash, Reston AU - Markes, J.-P. AU - Andersen, Dave AU - Bradley, Colin AU - Blain, Célia AU - Desmarais, Ronald AU - Gamroth, Darryl AU - Ito, Meguru AU - Jackson, Kate AU - Lach, Przemek AU - Pham, Laurie T2 - Adaptive Optics Systems III T2 - Proceedings of SPIE; 8447 T3 - Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491480 SP - 844753 KW - Closed-loop KW - Deformable mirrors KW - Field of regard KW - Image rotator KW - Mechanical design KW - Multiobject KW - On-sky demonstrator KW - Opto-mechanical design KW - Performance comparison KW - Pick-off KW - Subaru telescopes KW - Wave front sensors KW - Adaptive optics KW - Analog differential analyzers KW - Optical design KW - Electric appliances AB - Raven is a Multi-Object Adaptive Optics (MOAO) technical and scientific demonstrator which will be used on the Subaru telescope with the IRCS spectrograph. The optical and mechanical designs are finalised and the system is now being integrated in the lab at UVic. Raven features three open-loop wavefront sensors (WFS) patrolling a 3.5' field of regard, one on-axis LGS WFS, two science channels each equipped with a pick-off arm, an 11x11 actuator deformable mirror, a closed-loop WFS for calibration and performance comparison and an image rotator. This paper presents in detail the optical design and its performance, as well as the mechanical design. DA - 2012/09/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 02d508ae-29c5-4ea5-adda-5334c2677bce ER - TY - JOUR TI - SPIRou @ CFHT: spectrograph optical design DO - 10.1117/12.926697 AU - Thibault, Simon AU - Rabou, Patrick AU - Donati, Jean-Francois AU - Desaulniers, Pierre AU - Dallaire, Xavier AU - Artigau, Etienne AU - Pepe, Francesco AU - Micheau, Yoan AU - Vallée, Philippe AU - Barrick, Greg AU - Reshetov, Vlad AU - Hernandez, Olivier AU - Saddlemyer, Leslie AU - Pazder, John AU - Parès, Laurent P. AU - Doyon, Rene AU - Delfosse, Xavier AU - Kouach, Driss AU - Loop, David T2 - Ground-based and Airborne Instrumentation for Astronomy IV T2 - Proceedings of SPIE; 8446 T3 - Ground-Based and Airborne Instrumentation for Astronomy IV, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491473 SP - 844630 KW - CFHT KW - Echelle gratings KW - High precision KW - Near-IR KW - Spectropolarimetry KW - Astronomy KW - Cryogenics KW - Diffraction gratings KW - Infrared devices KW - Instruments KW - Spectrographs AB - SPIRou is a near-infrared, echelle spectropolarimeter/velocimeter under design for the 3.6m Canada-France-Hawaii Telescope (CFHT) on Mauna Kea, Hawaii. The unique scientific capabilities and technical design features are described in the accompanying (eight) papers at this conference. In this paper we focus on the lens design of the optical spectrograph. The SPIROU spectrograph is a near infrared fiber fed double pass cross dispersed spectrograph. The cryogenic spectrograph is connected with the Cassegrain unit by the two science fibers. It is also fed by the fiber coming from the calibration box and RV reference module of the instrument. It includes 2 off-axis parabolas (1 in double pass), an echelle grating, a train of cross disperser prisms (in double pass), a flat folding mirror, a refractive camera and a detector. This paper describes the optical design of the spectrograph unit and estimates the performances. In particular, the echelle grating options are discussed as the goal grating is not available from the market. © 2012 SPIE. DA - 2012/09/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a16efb8e-050e-42ee-9baf-f7c0b700a3ac ER - TY - JOUR TI - Introduction to the CFHT Legacy Survey final release (CFHTLS T0007) DO - 10.1117/12.925584 AU - Cuillandre, Jean-Charles AU - Withington, Kanoa AU - Hudelot, Patrick AU - Goranova, Yuliana AU - McCracken, Henry AU - Magnard, Frédéric AU - Mellier, Yannick AU - Regnault, Nicolas AU - Bétoule, Marc AU - Aussel, Hervé AU - Kavelaars, J. J. AU - Fernique, Pierre AU - Bonnarel, François AU - Ochsenbein, Francois AU - Ilbert, Olivier T2 - Observatory Operations: Strategies, Processes, and Systems IV T2 - Proceedings of SPIE; 8448 T3 - Observatory Operations: Strategies, Processes, and Systems IV, July 4-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491497 SP - 84480M KW - CdS KW - Cosmic shear KW - Curation KW - Dark energy KW - Dark matter KW - Data collection KW - Data sets KW - Full integration KW - High impact KW - In-phase KW - Optical KW - Photometric calibration KW - Prime-focus KW - Processing center KW - Red shift KW - Team planning KW - Virtual observatory KW - Wide-field imager KW - Buildings KW - Calibration KW - Data acquisition KW - Observatories KW - Photometry KW - Solar system KW - Surveys AB - The Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) is a high impact scientific program which will see its final official release open to the world in 2012. That release will seal the legacy aspect of the survey which has already produced a large collection of scientific articles with topics ranging from cosmology to the Solar system. The survey core science was focused on dark energy and dark matter: the full realization of the scientific potential of the data set gathered between 2003 and 2009 with the MegaCam wide-field imager mounted at the CFHT prime focus is almost complete with the Supernovae Legacy Survey (SNLS) team preparing its third and last release (SNLS5), and the CFHTLenS team planning the release based around the cosmic shear survey later this year. While the data processing center TERAPIX offered to the CFHTLS scientific community regular releases over the course of the survey in its data acquisition phase (T0001-T0006), the final release took three years to refine in order to produce a pristine data collection photometrically calibrated at better than the percent both internally and externally over the total survey surface of 155 square degrees in all five photometric bands (u*, g', r', i', z'). This final release, called T0007, benefits from the various advances in photometric calibration MegaCam has benefited through the joint effort between SNLS and CFHT to calibrate MegaCam at levels unexplored for an optical wide-field imager. T0007 stacks and catalogs produced by TERAPIX will be made available to the world at CADC while the CDS will offer a full integration of the release in its VO tools from VizieR to Aladin. The photometric redshifts have been produced to be released in phase with the survey. This proceeding is a general introduction to the survey and aims at presenting its final release in broad terms. DA - 2012/09/27 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b25ade50-95b0-44e4-8eb9-4911b2eb35eb ER - TY - JOUR TI - Woofer-tweeter adaptive optics in very strong turbulence using a magnetic-liquid deformable mirror DO - 10.1117/12.925174 AU - Brousseau, Denis AU - Véran, Jean-Pierre AU - Thibault, Simon AU - Borra, Ermanno F. AU - F.-Boivin, Simon T2 - Adaptive Optics Systems III T2 - Proceedings of SPIE; 8447 T3 - Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491480 SP - 84473Z KW - Adaptive optics systems KW - Deformable mirrors KW - High bandwidth KW - Low-bandwidth KW - Strong turbulence KW - Actuators KW - Adaptive optics KW - Bandwidth KW - Laser pulses KW - Loudspeakers KW - Liquids AB - We present progress towards the development of a woofer-tweeter adaptive optics (AO) system using the first 37 actuators of a 91-actuator magnetic-liquid deformable mirror (MLDM) and a magnetic 97-actuator DM from ALPAO. The MLDM, which has both very large single-actuator and inter-actuator strokes, but a low bandwidth, is used as woofer, whereas the high bandwidth and lower stroke ALPAO DM is used as tweeter. The ALPAO DM should improve the bandwidth of the MLDM while the MLDM will allow correction of strong aberrations. DA - 2012/09/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f3851c55-d807-403a-a825-7c201a1759f8 ER - TY - JOUR TI - Review of small-angle coronagraphic techniques in the wake of ground-based second-generation adaptive optics systems DO - 10.1117/12.927245 AU - Mawet, Dimitri AU - Pueyo, Laurent AU - Lawson, Peter AU - Mugnier, Laurent AU - Traub, Wesley AU - Boccaletti, Anthony AU - Trauger, John T. AU - Gladysz, Szymon AU - Serabyn, Eugene AU - Milli, Julien AU - Belikov, Ruslan AU - Kasper, Markus AU - Baudoz, Pierre AU - MacIntosh, Bruce AU - Marois, Christian AU - Oppenheimer, Ben AU - Barrett, Harrisson AU - Beuzit, Jean-Luc AU - Devaney, Nicolas AU - Girard, Julien AU - Guyon, Olivier AU - Krist, John AU - Mennesson, Bertrand AU - Mouillet, David AU - Murakami, Naoshi AU - Poyneer, Lisa AU - Savransky, Dmitri AU - Vérinaud, Christophe AU - Wallace, James K. T2 - Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave T2 - Proceedings of SPIE; 8442 T3 - Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491435 SP - 844204 KW - Coronagraphy KW - High contrast imaging KW - Observing strategy KW - Post processing KW - Working angle KW - Instruments KW - Millimeter waves KW - Space telescopes KW - Adaptive optics AB - Small-angle coronagraphy is technically and scientifically appealing because it enables the use of smaller telescopes, allows covering wider wavelength ranges, and potentially increases the yield and completeness of circumstellar environment - exoplanets and disks - detection and characterization campaigns. However, opening up this new parameter space is challenging. Here we will review the four posts of high contrast imaging and their intricate interactions at very small angles (within the first 4 resolution elements from the star). The four posts are: choice of coronagraph, optimized wavefront control, observing strategy, and post-processing methods. After detailing each of the four foundations, we will present the lessons learned from the 10+ years of operations of zeroth and first-generation adaptive optics systems. We will then tentatively show how informative the current integration of second-generation adaptive optics system is, and which lessons can already be drawn from this fresh experience. Then, we will review the current state of the art, by presenting world record contrasts obtained in the framework of technological demonstrations for space-based exoplanet imaging and characterization mission concepts. Finally, we will conclude by emphasizing the importance of the cross-breeding between techniques developed for both ground-based and space-based projects, which is relevant for future high contrast imaging instruments and facilities in space or on the ground. DA - 2012/08/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6cd4b109-1990-4bb0-97f2-969fca359bdc ER - TY - JOUR TI - High-contrast imaging in the Hyades with snapshot LOCI DO - 10.1117/12.926377 AU - Morzinski, Katie M. AU - Macintosh, Bruce A. AU - Close, Laird M. AU - Marois, Christian AU - Konopacky, Quinn AU - Patience, Jenny T2 - Adaptive Optics Systems III T2 - Proceedings of SPIE; 8447 T3 - Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491480 SP - 84470O KW - Brown dwarfs KW - High contrast imaging KW - Hyades KW - Image diversity KW - LOCI KW - PSF KW - Adaptive optics KW - Stars KW - Image processing AB - To image faint substellar companions obscured by the stellar halo and speckles, scattered light from the bright primary star must be removed in hardware or software. We apply the "locally-optimized combination of images" (LOCI) algorithm to 1-minute Keck Observatory snapshots of GKM dwarfs in the Hyades using source diversity to determine the most likely PSF. We obtain a mean contrast of 10-2 at 0.″01, 10-4 at <1″, and 10-5 at 5″. New brown dwarf and low-mass stellar companions to Hyades primaries are found in a third of the 84 targeted systems. This campaign shows the efficacy of LOCI on snapshot imaging as well as on bright wide binaries with off-axis LOCI, reaching contrasts sufficient for imaging 625-Myr late-L/early-T dwarfs purely in post-processing. DA - 2012/09/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2a4b182c-3c01-4e44-89cb-a9ece3c1f21e ER - TY - JOUR TI - Ultra violet imaging telescope (UVIT) on ASTROSAT DO - 10.1117/12.924507 AU - Kumar, Amit AU - Ghosh, S. K. AU - Hutchings, J. AU - Kamath, P. U. AU - Kathiravan, S. AU - Mahesh, P. K. AU - Murthy, J. AU - Nagbhushana, S. AU - Pati, A. K. AU - Rao, M. N. AU - Rao, N. K. AU - Sriram, S. AU - Tandon, S. N. T2 - Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray T2 - Proceedings of SPIE; 8443 T3 - Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491442 SP - 84431N KW - Angular resolution KW - CMOS STAR250 KW - Detector systems KW - Earth albedo KW - Field of views KW - Filter wheel KW - Multiwavelength KW - Photon counting KW - Primary mirrors KW - Satellite mission KW - Shift-and-add KW - Sun-shield KW - Three channel KW - UV KW - Visible band KW - Detectors KW - Gamma rays KW - Space telescopes KW - Optical telescopes AB - The Ultra Violet Imaging Telescope on ASTROSAT Satellite mission is a suite of Far Ultra Violet (FUV: 130 - 180 nm), Near Ultra Violet (NUV: 200 - 300 nm) and Visible band (VIS: 320-550nm) imagers. ASTROSAT is the multiwavelength mission of ISRO. UVIT will image the sky simultaneously in three channels with a field of view diameter of ̃ 28 arcminutes and an angular resolution < 1.8". Two identical co-Aligned telescopes (T1, T2) of Ritchey-Chretien configuration (Primary mirror of ̃375 mm diameter) collect the celestial radiation and feed the detector systems via a selectable filter on a filter wheel mechanism; gratings are available in the filter wheels of FUV and NUV channels for slitless low-resolution spectroscopy. The photon-counting detector system for each of the 3 channels is generically identical. one of the telescopes images in the FUV channel, while the other images in NUV and VIS channels via a beamsplitter. Images from the VIS channel are principally used for measuring drift, used in construction of images on the ground by shift and add, and to reconstruct absolute aspect of the images. Adequate baffling has been provided for reducing the scattered background from the Sun, earth albedo and other bright objects. The one-Time opening mechanical cover on each telescope also works as a Sun-shield after deployment. We will present the overall (mechanical, optical and electrical) design of the payload. © 2012 SPIE. DA - 2012/09/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ebd83cd1-a97f-41ec-96ae-c8a8728a71e9 ER - TY - JOUR TI - SPICES: a 1.5-m space coronagraph for spectro-polarimetric characterization of cold exoplanets DO - 10.1117/12.925559 AU - Maire, Anne-Lise AU - Boccaletti, Anthony AU - Schneider, Jean AU - Galicher, Raphaël AU - Baudoz, Pierre AU - Stam, Daphne AU - Traub, Wesley AU - Lagage, Pierre-Olivier AU - Gratton, Raffaele T2 - Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave T2 - Proceedings of SPIE; 8442 T3 - Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491435 SP - 84420I KW - Circumstellar disks KW - Exo-planets KW - High angular resolutions KW - High contrast imaging KW - Ice giants KW - Integral field KW - Physicochemical property KW - Visible light KW - Chemical properties KW - Imaging techniques KW - Instruments KW - Millimeter waves KW - Optical design KW - Polarimeters KW - Space telescopes KW - Food products AB - The study of the physico-chemical properties of wide-separated exoplanets (> 1 AU) is a major goal of highcontrast imaging techniques. SPICES (Spectro-Polarimetric Imaging and Characterization of Exoplanetary Systems) is a project of space coronagraph dedicated to the spectro-polarimetric analysis of gas and ice giant planets, super-Earths and circumstellar disks in visible light at a spectral resolution of about 40. After recalling the science cases of the mission, we describe the optical design and the critical subsystems of the instrument. We then discuss the SPICES performance that we derived from numerical simulations. DA - 2012/08/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 26344bc2-f6d4-4b60-bd59-776dab3e3ec9 ER - TY - JOUR TI - SPIRou @CFHT: design of the instrument control system DO - 10.1117/12.926392 AU - Barrick, Gregory A. AU - Vermuelen, Tom AU - Baratchart, Sébastien AU - Reshetov, Vladimir A. AU - Wang, Shiang-Yu AU - Dolon, François AU - Hernandez, Olivier AU - Pepe, Francesco AU - Bouchy, François AU - Dunn, Jennifer AU - Dupieux, Michel AU - Gallou, Gérard AU - Larrieu, Marie AU - Fonteneau, Alexandre AU - Moreau, François AU - Wildi, François AU - Parès, Laurent P. AU - Thomas, James N. AU - Yan, Chi-Hung AU - Doyon, René AU - Donati, Jean-François AU - Vallée, Philippe AU - Artigau, Étienne AU - Delfosse, Xavier AU - Rabou, Patrick AU - Thibault, Simon AU - Kouach, Driss AU - Loop, David T2 - Software and Cyberinfrastructure for Astronomy II T2 - Proceedings of SPIE; 8451 T3 - Software and Cyberinfrastructure for Astronomy II, July 1-4, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491527 SP - 84513J KW - CFHT KW - Control-command KW - Fast guiding KW - High precision KW - Near-IR KW - Spectropolarimetry KW - Thermal control KW - Tip-tilt KW - Algorithms KW - Stars KW - Velocity measurement KW - Velocimeters AB - SPIRou is a near-IR (0.98-2.35μm), echelle spectropolarimeter / high precision velocimeter being designed as a next-generation instrument for the 3.6m Canada-France-Hawaii Telescope on Mauna Kea, Hawaii, with the main goals of detecting Earth-like planets around low-mass stars and magnetic fields of forming stars. The unique scientific and technical capabilities of SPIRou are described in a series of eight companion papers. In this paper, the means of controlling the instrument are discussed. Most of the instrument control is fairly normal, using off-the-shelf components where possible and reusing already available code for these components. Some aspects, however, are more challenging. In particular, the paper will focus on the challenges of doing fast (50 Hz) guiding with 30 mas repeatability using the object being observed as a reference and on thermally stabilizing a large optical bench to a very high precision (∼1 mK). DA - 2012/09/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9a3e6251-3bde-4d46-a1f5-4a2ec87a8502 ER - TY - JOUR TI - TMT NFIRAOS: adaptive optics for the Thirty Meter Telescope DO - 10.1117/12.925087 AU - Herriot, Glen AU - Andersen, David AU - Atwood, Jenny AU - Byrnes, Peter AU - Boucher, Marc-André AU - Boyer, Corinne AU - Caputa, Kris AU - Correia, Carlos AU - Dunn, Jennifer AU - Ellerbroek, Brent AU - Fitzsimmons, Joeleff AU - Gilles, Luc AU - Hickson, Paul AU - Hill, Alexis AU - Kerley, Dan AU - Pazder, John AU - Reshetov, Vlad AU - Roberts, Scott AU - Smith, Malcolm AU - Véran, Jean-Pierre AU - Wang, Lianqi AU - Wevers, Ivan T2 - Adaptive Optics Systems III T2 - Proceedings of SPIE; 8447 T3 - Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491480 SP - 84471M KW - Conducting performance KW - Diffraction limited KW - Field of views KW - First-light adaptive optics system KW - High precision KW - Laser guide star KW - Multi-conjugate adaptive optics systems KW - NFIRAOS KW - Sky coverage KW - Optical telescopes AB - NFIRAOS is the first-light adaptive optics system planned for the Thirty Meter Telescope, and is being designed at the National Research Council of Canada's Herzberg Institute of Astrophysics. NFIRAOS is a laser guide star multi-conjugate adaptive optics system - a practical approach to providing diffraction limited image quality in the NIR over a 30" field of view, with high sky coverage. This will enable a wide range of TMT science that depends upon the large corrected field of view and high precision astrometry and photometry. We review recent progress developing the design and conducting performance estimates for NFIRAOS. DA - 2012/09/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b14da8a7-fe3a-49d1-a956-fc024efa3b78 ER - TY - JOUR TI - Tip/Tilt point spread function reconstruction for laser guide star multi conjugate adaptive optics DO - 10.1117/12.926928 AU - Gilles, L. AU - Correia, C. AU - Véran, J.P. AU - Wang, L. AU - Ellerbroek, B. L. T2 - Adaptive Optics Systems III T2 - Proceedings of SPIE; 8447 T3 - Adaptive Optics Systems III, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491480 SP - 844729 KW - Anisoplanatism KW - Capture error KW - Experimental validations KW - High-order KW - Multi-conjugate adaptive optics systems KW - Natural guide star KW - Point spread function reconstruction KW - Post processing KW - Simulation model KW - Thirty Meter Telescope KW - Wave front sensors KW - Algorithms KW - Atmospheric turbulence KW - Computer simulation KW - Covariance matrix KW - Lasers KW - Optical transfer function KW - Sensors KW - Stars KW - Wavefronts AB - In adaptive optics systems employing laser guide stars, the tip/tilt contribution to the long exposure point spread function must be estimated separately from the high-order tip/tilt removed point spread function because this component is estimated separately from a single or multiple low-order natural guide star wavefront sensors. This paper investigates this problem for laser guide star multi conjugate adaptive optics. The approach is based on the scheme developed by Flicker in 2003 [1], and consists in post-processing the measurement covariance matrix of multiple low-order natural guide star wavefront sensors controlling tip/tilt and tilt anisoplanatism. An innovative simulation model based "balanced" algorithm is introduced to capture error terms not accounted for in Flicker's algorithm. Sample enclosed energy results for the Thirty Meter Telescope multi conjugate adaptive optics system demonstrate the superiority of the balanced method and call for further analytical work and experimental validation. DA - 2012/09/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cbc826b5-7c30-4dd3-be4a-978f43497eda ER - TY - JOUR TI - Status of the Raven MOAO science demonstrator DO - 10.1117/12.926854 AU - Andersen, David R. AU - Bradley, C. AU - Lardière, O. AU - Blain, C. AU - Correia, C. AU - Desmarais, R. AU - Gamroth, D. AU - Ito, M. AU - Jackson, K. AU - Lach, P. AU - Nash, R. AU - Pham, L. AU - Véran, J.-P. T2 - Adaptive Optics Systems III T2 - Proceedings of SPIE; 8447 T3 - Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491480 SP - 84473F KW - Alignment technique KW - Calibration unit KW - Deformable mirrors KW - Ground layer KW - Laser guide star KW - Multiobject KW - Multiple source KW - Phase screen KW - Wave front sensors KW - Calibration KW - Electric appliances KW - Adaptive optics AB - Raven is a Multi-Object Adaptive Optics (MOAO) scientific demonstrator which will be used on-sky at the Subaru observatory. Raven is currently being built at the University of Victoria AO Lab. In this paper, we present an overview of the final Raven design and then describe lab tests involving prototypes of Raven subsystems. The final design includes three open loop wavefront sensors (WFSs), a laser guide star WFS and two figure/truth WFSs. Two science channels, each containing a deformable mirror (DM), feed light to the Subaru IRCS spectrograph. Central to the Raven MOAO system is a Calibration Unit (CU) which contains multiple sources, a telescope simulator including two rotating phase screens and a ground layer DM that can be used to calibrate and test Raven. We are working with the Raven CU and open loop WFSs to test and validate our open loop calibration and alignment techniques. DA - 2012/09/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 44f70959-30be-4822-a9db-04ab7ac36c9b ER - TY - JOUR TI - The Gemini Planet Imager: integration and test DO - 10.1117/12.926721 AU - Macintosh, Bruce A. AU - Anthony, Andre AU - Atwood, Jennifer AU - Barriga, Nicolas AU - Bauman, Brian AU - Caputa, Kris AU - Chilcote, Jeffery AU - Dillon, Daren AU - Doyon, René AU - Dunn, Jennifer AU - Gavel, Donald T. AU - Galvez, Ramon AU - Goodsell, Stephen AU - Graham, James R. AU - Hartung, Markus AU - Isaacs, Joshua AU - Kerley, Dan AU - Konopacky, Quinn AU - Labrie, Kathleen AU - Larkin, James E. AU - Maire, Jerome AU - Marois, Christian AU - Millar-Blanchaer, Max AU - Nunez, Arturo AU - Oppenheimer, Ben R. AU - Palmer, David W. AU - Pazder, John AU - Perrin, Marshall AU - Poyneer, Lisa A. AU - Quiroz, Carlos AU - Rantakyro, Frederik AU - Reshtov, Vlad AU - Saddlemyer, Leslie AU - Sadakuni, Naru AU - Savransky, Dmitry AU - Sivaramakrishnan, Anand AU - Smith, Malcolm AU - Soummer, Remi AU - Thomas, Sandrine AU - Wallace, J. Kent AU - Weiss, Jason AU - Wiktorowicz, Sloane T2 - Ground-based and Airborne Instrumentation for Astronomy IV T2 - Proceedings of SPIE; 8446 T3 - Ground-Based and Airborne Instrumentation for Astronomy IV, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491473 SP - 84461U KW - Adaptive optics systems KW - Coronagraphy KW - Direct detection KW - Exo-planets KW - Extra solar planets KW - Hardware and software KW - Integral field spectrograph KW - Laboratory testing KW - Lyot coronagraphs KW - Multiwavelength KW - Post processing KW - Speckle suppression KW - Wave front sensors KW - Adaptive optics KW - Astronomy KW - Instruments KW - Software testing AB - The Gemini Planet Imager is a next-generation instrument for the direct detection and characterization of young warm exoplanets, designed to be an order of magnitude more sensitive than existing facilities. It combines a 1700-actuator adaptive optics system, an apodized-pupil Lyot coronagraph, a precision interferometric infrared wavefront sensor, and a integral field spectrograph. All hardware and software subsystems are now complete and undergoing integration and test at UC Santa Cruz. We will present test results on each subsystem and the results of end-to-end testing. In laboratory testing, GPI has achieved a raw contrast (without post-processing) of 10-6 5σ at 0.4'', and with multiwavelength speckle suppression, 2x10^-7 at the same separation. DA - 2012/09/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c886db19-5332-4f04-88f5-fbe1552f72bd ER - TY - JOUR TI - Atmospheric characterization of cold exoplanets with a 1.5-m space coronagraph DO - 10.1117/12.925563 AU - Maire, Anne-Lise AU - Galicher, Raphaël AU - Boccaletti, Anthony AU - Baudoz, Pierre AU - Schneider, Jean AU - Cahoy, Kerri AU - Stam, Daphne AU - Traub, Wesley T2 - Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave T2 - Proceedings of SPIE; 8442 T3 - Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491435 SP - 84424G KW - Atmosphere models KW - Atmospheric characterization KW - Exo-planets KW - High angular resolutions KW - High contrast imaging KW - Integral field KW - Jupiters KW - Metallicities KW - Parameter spaces KW - Potential targets KW - Solar type stars KW - Spectral properties KW - Surface coverages KW - Technical feasibility KW - Computer simulation KW - Imaging techniques KW - Instruments KW - Millimeter waves KW - Space telescopes KW - Stars KW - Earth (planet) AB - Several small space coronagraphs have been proposed to characterize cold exoplanets in reected light. Studies have mainly focused on technical feasibility because of the huge star/planet ux ratio to achieve in the close-in stellar environment (108-1010 at 0.2). However, the main interest of such instruments, the analysis of planet properties, has remained highly unexplored so far. We performed numerical simulations to assess the ability of a small space coronagraph to retrieve spectra of mature Jupiters, Neptunes and super-Earths under realistic assumptions. We describe our assumptions: exoplanetary atmosphere models, instrument numerical simulation and observing conditions. Then, we define a criterion and use it to determine the required exposure times to measure several planet parameters from their spectra (separation, metallicity, cloud and surface coverages) for particular cases. Finally, we attempt to define a parameter space of the potential targets. In the case of a solar-type star, we show that a small coronagraph can characterize the spectral properties of a 2-AU Jupiter up to 10 pc and the cloud and surface coverage of super-Earths in the habitable zone for a few stars within 4{5 pc. Potentially, SPICES could perform analysis of a hypothetical Earth-size planet around α Cen A and B. DA - 2012/08/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 548990f5-8f30-4891-a1dd-4abf0843b153 ER - TY - JOUR TI - SPIRou @CFHT: Fiber links and pupil slicer DO - 10.1117/12.926084 AU - Micheau, Yoan AU - Bouchy, François AU - Pepe, Francesco AU - Chazelas, Bruno AU - Kouach, Driss AU - Parès, Laurent AU - Donati, Jean-François AU - Barrick, Gregory AU - Rabou, Patrick AU - Thibault, Simon AU - Saddlemyer, Leslie AU - Perruchot, Sandrine AU - Delfosse, Xavier AU - Striebig, Nicolas AU - Gallou, Gérard AU - Loop, David AU - Pazder, John T2 - Ground-based and Airborne Instrumentation for Astronomy IV T2 - Proceedings of SPIE; 8446 T3 - Ground-Based and Airborne Instrumentation for Astronomy IV, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491473 SP - 84462R KW - CFHT KW - Fluoride fibers KW - FRD KW - High precision KW - Pupil slicer KW - Scrambling KW - Spectropolarimetry KW - Cryogenics KW - Spectrographs KW - Stars KW - Velocimeters KW - Velocity measurement KW - Fibers AB - SPIRou is a near-IR (0.98-2.35μm), echelle spectropolarimeter / high precision velocimeter being designed as a next-generation instrument for the 3.6m Canada-France-Hawaii Telescope on Mauna Kea, Hawaii, with the main goal of detecting Earth-like planets around low mass stars and magnetic fields of forming stars. The unique scientific and technical capabilities of SPIRou are described in a series of seven companion papers. In this paper, the fiber links which connects the polarimeter unit to the cryogenic spectrograph unit (35 meter apart) are described. The pupil slicer which forms a slit compatible with the spectrograph entrance specifications is also discussed in this paper. Some challenging aspects are presented. In particular this paper will focus on the manufacturing of 35 meter fibers with a very low loss attenuation (< 13dB/km) in the non-usual fiber spectral domain from 0.98 μm to 2.35 μm. Other aspects as the scrambling performance of the fiber links to reach high accuracy radial velocity measurements (1m/s) and the design of the pupil slicer exposed at a cryogenic and vacuum environment will be discussed. DA - 2012/09/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9a793ccd-5317-486b-8122-81e756ec3d56 ER - TY - JOUR TI - 'Imaka: working towards very wide-field of view AO DO - 10.1117/12.925530 AU - Chun, M. AU - Lai, O. AU - Cuillandre, J.-C. AU - Richer, H. AU - Toomey, D. AU - Salmon, D. AU - Carlberg, R. AU - Andersen, D. AU - Burgarella, D. AU - Ho, K. AU - Pazder, J. AU - Bertin, E. T2 - Adaptive Optics Systems III T2 - Proceedings of SPIE; no. 8447 T3 - Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491480 SP - 84471G KW - Angular resolution KW - Antarctica KW - Fields of views KW - Ground-based telescopes KW - Ground-layer adaptive optics KW - Optical turbulence KW - Orders of magnitude KW - Paranal KW - Wide field imaging KW - Wide field of view KW - Wide-field KW - Engineering KW - Molecular physics KW - Adaptive optics AB - Ground-layer adaptive optics (GLAO) has the potential to dramatically increase the efficiency and capabilities of existing ground-based telescopes over a broad range of astronomical science. Recent studies of the optical turbulence above several astronomical sites (e.g. Mauna Kea, Paranal, and Antarctica) show that GLAO can be extended to fields of view of several tens of arcminutes in diameter, larger than previously thought, with angular resolutions close to the free-atmosphere seeing. This is a pivotal result since GLAO science cases benefit from the largest possible corrected fields of view. The corrected areal field of a GLAO system is potentially 2-3 orders of magnitude larger than has been demonstrated to date. The 'Imaka team is working toward an instrument that takes advantage of the one-degree field afforded by Mauna Kea. In this paper we summarize the design/simulation work to date along with our plan to develop an instrument that reaches for this wide field of view. © 2012 SPIE. DA - 2012/09/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d0805b88-c81b-4545-9391-eba9b9db82b5 ER - TY - JOUR TI - TMT DMs final design and advanced prototyping results at Cilas DO - 10.1117/12.925313 AU - Sinquin, Jean-Christophe AU - Bastard, Arnaud AU - Boyer, Corinne AU - Cornette, Sébastien AU - Cousty, Raphaël AU - Ellerbroek, Brent AU - Gilbert, Xavier AU - Gourdet, Benoit AU - Grasser, Régis AU - Groeninck, Denis AU - Guillemard, Claude AU - Herriot, Glen AU - Iannacone, Albert AU - Jeulin, Antoine AU - Moreau, Aurélien AU - Pagès, Hubert AU - Wang, Lianqi T2 - Adaptive Optics Systems III T2 - Proceedings of SPIE; 8447 T3 - Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491480 SP - 844706 KW - Adaptive optics systems KW - Construction phase KW - Deformable mirrors KW - Low temperatures KW - Operational temperature KW - Piezomaterials KW - Piezostack actuators KW - SAM KW - Thermal behaviors KW - Thirty Meter Telescope KW - Actuators KW - Adaptive optics KW - Finite element method KW - Laser pulses KW - Metal drawing KW - Specifications AB - In order to prepare for the construction phase of the two Deformable Mirrors (DMs), which will be used in the Thirty Meter Telescope (TMT) first light Adaptive Optics (AO) system, Cilas has advanced the design of these two large size piezo DMs and has manufactured and tested a scaled demonstration prototype. The work done allowed significant reduction of the risks related to the demanding specifications of the TMT DMs; the main issues were: (i) Large pupil (up to 370 mm) and high order (up to 76x76); (ii) Relatively low operational temperature (DMs working at -30°C); (iii) New piezo material. It is important to develop such a prototype to take into account these three specifications all together (dimension, low temperature and new piezo material). The new prototype is a 6x60 actuators and has the same characteristics as the future TMT DMs. In this paper, we give the conclusions of the work through the presentation of the following items: (i) Design and finite element analysis of the two DMs and prototype; (ii) Test results obtained with the prototype with validation of the finite element analysis and compliance with the TMT AO specifications; (iii) Special focus on thermal behavior, actuator reliability and shape at rest stability. © 2012 SPIE. DA - 2012/09/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3e7ea4f6-e0b0-49ac-a307-0fc7c07cad61 ER - TY - JOUR TI - Improved red sensitivity deep depletion e2v devices for the Gemini North GMOS instrument DO - 10.1117/12.927065 AU - Roth, Katherine C. AU - Kleinman, Scot J. AU - Chiboucas, Kristin AU - Schiavon, Ricardo AU - Hanna, Kevin AU - Rippa, Mathew AU - White, John K. AU - Walls, Brian AU - Yamasaki, Chris AU - Murowinski, Richard AU - Labrie, Kathleen AU - Gimeno, German AU - Simpson, Mark T2 - Ground-based and Airborne Instrumentation for Astronomy IV T2 - Proceedings of SPIE; 8446 T3 - Ground-Based and Airborne Instrumentation for Astronomy IV, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491473 SP - 84463V KW - Blue wavelength KW - CCDs KW - Deep depletion KW - e2v KW - GMOS KW - Hamamatsu KW - New detectors KW - Pixel size KW - Wavelength ranges AB - The GMOS-N instrument was upgraded with new CCDs in October 2011, improving the instrument sensitivity at both red and blue wavelengths. The deep depletion devices are manufactured by e2v (42-90 with multi-layer 3 coating) and extend the useful wavelength range of GMOS-N to 0.98 microns (compared to 0.94 microns previously). These detectors also exhibit much lower fringing than the original EEV detectors that had been in use since GMOS-N was commissioned in 2002. All other characteristics of the new detectors (readout speed, pixel size and format, detector controller, noise, gain) are similar to the original CCDs. Operating the new detectors in all amps mode (2 per CCD) has effectively improved the readout speed by a factor of 2. The new devices were selected to provide a quick and relatively simply upgrade route while technical issues with the Hamamatsu devices, originally planned for the upgrade, were investigated and resolved. We discuss the rationale for this interim upgrade, the upgrade process and attending issues. The new detectors have been used for science since November 2011. We present commissioning results illustrating the resulting gain in sensitivity over the original detector package. Gemini is still committed to installing Hamamatsu devices, which will further extend the useful wavelength range of GMOS to 1.03 microns, in both North and South GMOS instruments. We discuss the status of the Hamamatsu project and the current planned schedule for these future upgrades. DA - 2012/09/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3f0a3c1c-6717-41d0-9b21-6c596e42f43c ER - TY - JOUR TI - Test results for the Gemini Planet Imager data reduction pipeline DO - 10.1117/12.926202 AU - Maire, Jérôme AU - Perrin, Marshall D. AU - Doyon, René AU - Chilcote, Jeffrey AU - Larkin, James E. AU - Weiss, Jason L. AU - Marois, Christian AU - Konopacky, Quinn M. AU - Millar-Blanchaer, Maxwell AU - Graham, James R. AU - Dunn, Jennifer AU - Galicher, Raphael AU - Marchis, Franck AU - Wiktorowicz, Sloane J. AU - Labrie, Kathleen AU - Thomas, Sandrine J. AU - Goodsell, Stephen J. AU - Rantakyro, Fredrik T. AU - Palmer, David W. AU - Macintosh, Bruce A. T2 - Software and Cyberinfrastructure for Astronomy II T2 - Proceedings of SPIE; 8451 T3 - Software and Cyberinfrastructure for Astronomy II, July 1-4, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491527 SP - 84513G KW - Command line KW - Data cube KW - Debris disk KW - Exo-planets KW - Flexible modular KW - High contrast imaging KW - Image reduction KW - Integral field spectrograph KW - Near Infrared KW - Photometric calibration KW - Pipeline tests KW - Source codes KW - Speckle suppression KW - Calibration KW - Data processing KW - Instruments AB - The Gemini Planet Imager (GPI) is a new facility instrument for the Gemini Observatory designed to detect and characterize planets and debris disks orbiting nearby stars; its science camera is a near infrared integral field spectrograph. We have developed a data pipeline for this instrument, which will be made publicly available to the community. The GPI data reduction pipeline (DRP) incorporates all necessary image reduction and calibration steps for high contrast imaging in both the spectral and polarimetric modes, including datacube generation, wavelength solution, astrometric and photometric calibrations, and speckle suppression via ADI and SSDI algorithms. It is implemented in IDL as a flexible modular system, and includes both command line and graphical interface tools including a customized viewer for GPI datacubes. This GPI data reduction pipeline is currently working very well, and is in use daily processing data during the instrument's ongoing integration and test period at UC Santa Cruz. Here we summarize the results from recent pipeline tests, and present reductions of instrument test data taken with GPI. We will continue to refine and improve these tools throughout the rest of GPI's testing and commissioning, and they will be released to the community, including both IDL source code and compiled versions that can be used without an IDL license. DA - 2012/09/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1267dde6-43ae-48cd-8cdd-bc9cb692e390 ER - TY - JOUR TI - Design and test results of the calibration unit for the MOAO demonstrator RAVEN DO - 10.1117/12.925489 AU - Lavigne, J.-F. AU - Lamontagne, F. AU - Anctil, G. AU - Wang, M. AU - Tremblay, M. AU - Lardiere, O. AU - Nash, R. AU - Andersen, D. AU - Savard, M. AU - Côté, P. AU - Bradley, C.H. AU - Châteauneuf, F. T2 - Adaptive Optics Systems III T2 - Proceedings of SPIE; 8447 T3 - Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491480 SP - 844754 KW - Adaptive optics systems KW - Calibration unit KW - Illumination system KW - Interaction matrices KW - Model prediction KW - Multiobject KW - Subaru telescopes KW - System test KW - Calibration KW - Optical design KW - Optical telescopes AB - INO has designed, assembled and tested the Raven Multi-Object Adaptive Optics demonstrator calibration unit. This sub-system consists in a telescope simulator that will allow aligning Raven's components during its integration, testing its Adaptive Optics performances in the laboratory and at the telescope, and calibrating the Adaptive Optics system by building the interaction matrix and measuring the non-common path aberrations. The system is presented with the challenges that needed to be overcome during the design and integration phases. The system test results are also presented and compared to the model predictions. DA - 2012/09/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2d897c13-ace0-4cae-9f30-1f8ca10e167e ER - TY - JOUR TI - Understanding charge dynamics in silicon dangling bond structures for nanoscale devices AU - Livadaru, L. AU - Pitters, J. L. AU - Taucer, M. AU - Wolkow, R. A. T2 - Nanotechnology 2012: Technical Proceedings of the 2012 NSTI Nanotechnology Conference and Expo. Volume 1: Advanced materials, CNTs, particles, films and composites T3 - Nanotech Conference and Expo 2012, June 18-21, 2012, Santa Clara, CA, USA SN - 9781466562752 SP - 35 EP - 37 KW - Artificial molecule KW - Atomic scale KW - Building blockes KW - Charge dynamics KW - Charge qubits KW - Computing architecture KW - Device architectures KW - Electron dynamics KW - External control KW - Ionic state KW - Nanoscale device KW - Polarization properties KW - Quantum-dot cellular automata KW - Si(001) surfaces KW - Silicon dangling bonds KW - Silicon surfaces KW - Dynamics KW - Electronic structure KW - Fluidics KW - Molecules KW - Nanowires KW - Scanning tunneling microscopy KW - Sequential machines KW - Nanotechnology AB - A dangling bond (DB) on a silicon surface atomic has been found to behave as an atomic-scale quantum dot. This opens up the possibility of using DBs as building blocks for novel electronic structures, pushing the ultimate limits of nanoscale devices. Examples include: artificial molecules, nanowires, and alternate computing architectures such as the Quantum-Dot Cellular Automata (QCA). We study theoretically various aspects of DB structures on an H-terminated 2x1 Si(001) surface, which are of primary interest for the advancement of any device architecture: (i) The "diatomic" artificial DB molecule, composed of two tunnel-coupled DBs; its coherence and polarization properties in different ionic states; its potential as a charge qubit. (ii) The interaction of such DB structures with external control electrodes and manipulators, including the interaction with a scanning tunneling microscopy (STM) probe. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e06a1785-d537-45cf-8018-bb881700683b ER - TY - JOUR TI - Comprehensive microscopy analysis of Au/Ag nanoclusters on silica nanospheres AU - Qian, H. AU - Shen, W.-Z. AU - Cui, K. AU - Cho, J.-Y. AU - Fenniri, H. T2 - Nanotechnology 2012: Technical Proceedings of the 2012 NSTI Nanotechnology Conference and Expo. Volume 1: Advanced materials, CNTs, particles, films and composites T3 - Nanotech Conference and Expo 2012, June 18-21, 2012, Santa Clara, CA, USA SN - 9781466562745 SP - 87 EP - 90 KW - Bimetallic nanoclusters KW - ED KW - HAADF KW - HRTEM KW - STEM KW - Energy dispersive spectroscopy KW - Films KW - Nanotechnology KW - Silica KW - Silver alloys KW - Transmission electron microscopy KW - Nanocomposite films AB - Gold/silver (Au/Ag) bimetallic nanoclusters (shell) on silica (Au/Ag @ SiO 2) were synthesized by layer-by-layer technique. By adjusting the mole ratio of Au and Ag, the bimetallic alloy on the SiO 2 nanoshpere surface posseses tunable surface plasmon resonance. Several transmission electron microscopy (TEM) techniques have been applied to characterize the structure and morphology of the bimetallic nanoclusters, including scanning transmission electron microscopy (STEM) tomography, high angle angular dark field (HAADF) imaging, energy dispersive X-ray (EDX) spectoscopy, high resolution TEM (HRTEM) and electron diffraction (ED). The results revealed the Au/Ag alloy nanoclusters were interconnected on the surface of SiO 2 nanospheres with the nanoscale roughess varied with the mole ratio of Au and Ag. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fca3446c-b07e-4ebc-87ee-c1fa3559a34b ER - TY - JOUR TI - Synthesis, characterization and viscoelastic properties of nanocrystalline cellulose grafted with poly(N-isopropylacrylamide) AU - Hemraz, U. D AU - Danumah, C. AU - Lu, A. AU - Boluk, Y. T2 - Nanotechnology 2012: Technical Proceedings of the 2012 NSTI Nanotechnology Conference and Expo. Volume 1: Advanced materials, CNTs, particles, films and composites T3 - Nanotech Conference and Expo 2012, June 18-21, 2012, Santa Clara, CA, USA SN - 9781466562745 SP - 640 EP - 643 KW - Functionalizations KW - Functionalized KW - Living radical polymerization KW - Lower critical solution temperature KW - N-isopropylacrylamides KW - Nanocrystalline cellulose KW - Polymer chains KW - Polymer grafting KW - Resulting materials KW - Rheometry KW - Stable systems KW - Thermoresponsive polymer KW - Viscoelastic properties KW - Viscosity value KW - Acrylic monomers KW - Cellulose derivatives KW - Grafting (chemical) KW - Living polymerization KW - Polymers KW - Rheology KW - Shear viscosity KW - Thermodynamic properties KW - Viscoelasticity KW - Nanocomposite films KW - Copolymerization KW - Low Temperature KW - Polyacrylics KW - Thin Films AB - Nanocrystalline cellulose (NCC) was grafted with the thermo-responsive polymer poly(N-isopropylacrylamide) (Nipaam) via living radical polymerization. Various techniques were used to characterize the physical, chemical, morphological and thermal properties of the resulting material. The viscoelastic properties and the stability of the functionalized NCC were compared to the unmodified NCC using rheometry. The shear viscosity of the NCC suspension decreased slightly with an increase in temperature from 20°C to 45°C, indicating a stable system. The storage modulus and shear viscosity values both exhibited a burst increase at about 32.5°C, which is assigned to be the lower critical solution temperature (LCST) of poly(Nipaam). This indicates the successful functionalization of Nipaam polymer chains on NCC. In addition, the thermodynamic property of poly(Nipaam) also prevailed on the grafted NCC. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 927d8c4c-3486-4ac6-b6e4-6e55e41498e8 ER - TY - JOUR TI - Nanocomposites of nanocrystalline cellulose for biosensor applications AU - Incani, V. AU - Danumah, C. AU - Boluk, Y. T2 - Nanotechnology 2012: Technical Proceedings of the 2012 NSTI Nanotechnology Conference and Expo. Volume 3: Bio Sensors, Instruments, Medical, Environment and Energy T3 - Nanotech Conference and Expo 2012, June 18-21, 2012, Santa Clara, CA, USA SN - 9781466562769 SP - 13 EP - 16 KW - Biosensing applications KW - Biosensor applications KW - Carbodiimides KW - Cationic polyethylenimine KW - Chemical affinities KW - Enzymes activity KW - Freeforms KW - Gold nanoparticles KW - Immobilized enzyme KW - Its efficiencies KW - Metallic nanoparticles KW - Nanocrystalline cellulose KW - Natural cellulose fibers KW - Renewable sources KW - Surface area KW - UV-visible KW - Biosensors KW - Cellulose derivatives KW - Exhibitions KW - Fluorescence spectroscopy KW - Glucose oxidase KW - Glucose sensors KW - Medical nanotechnology KW - Metal nanoparticles KW - Nanocomposites KW - Nanotechnology KW - Sensors KW - Enzyme immobilization KW - Cellulose Derivatives KW - Enzymes KW - Glucose KW - Gold Compounds KW - Sensors AB - In this work, we describe the use of a composite material made of a renewable source and metallic nanoparticles for biosensing applications. NCC is a product isolated from natural cellulose fibers, which is of approx. 100 nm long and 10 nm wide in size. We augmented the surface area and chemical affinity of NCC by optimally dressing it with gold nanoparticles (AuNP). The deposition of AuNP on NCC was controlled by using cationic Polyethylenimine (PEI). AuNPs were thio-funtionalized prior to enzyme immobilization and the enzyme (glucose oxidase) was conjugated on the composite by carbodiimide (EDC)/NHS coupling. Using UV-visible and fluorescence spectroscopy in the presence of a specific substrate we monitored the activity of the immobilized enzymes, and its efficiency was compared with that of the enzyme in free form. Our results using FT-IR and SEM show that thiol-AuNPs were attached to the surface of NCC. The enzymes activity were measured and quantified using different kit assays and proved that the enzymes were attached to the support and maintained their activity. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c3c53346-ddd2-4be2-aeac-3b6639aa91ff ER - TY - JOUR TI - Multiscale modeling of the structure and thermodynamics of chemically modified NCC for rational design of NCC-based nanocomposites, gels, and foams AU - Stoyanov, Stanislav R. AU - Lyubimova, O. AU - Cuervo, J. E. AU - Gusarov, S. AU - Kobryn, A. E. AU - Blinov, N. AU - Kovalenko, A. T2 - TAPPI International Conference on Nanotechnology for Renewable Materials 2012 T3 - TAPPI International Conference on Nanotechnology for Renewable Materials 2012, June 4-7, 2012, Montreal, QC, Canada SN - 9781627480536 SP - 624 DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5b335a89-27ca-4371-a587-f7cc6d57833a ER - TY - JOUR TI - Cationic liposome-mediated CXCR4 gene delivery into hematopoietic stem/progenitor cells: implications for clinical transplantation and gene therapy DO - 10.1089/scd.2011.0297 AU - Gul-Uludag, Hilal AU - Xu, Peng AU - Marquez-Curtis, Leah A. AU - Xing, James AU - Janowska-Wieczorek, Anna AU - Chen, Jie T2 - Stem Cells and Development SN - 1547-3287 VL - 21 IS - 10 SP - 1587 EP - 1596 KW - CD34 antigen KW - chemokine receptor CXCR4 KW - liposome KW - stromal cell derived factor 1alpha KW - cell migration KW - cell viability KW - chemotaxis KW - cytotoxicity KW - flow cytometry KW - gene overexpression KW - genetic transfection KW - hematopoietic stem cell KW - in vitro gene transfer KW - priority journal KW - Antigens, CD34 KW - Cell Survival KW - Cells, Cultured KW - Chemokine CXCL12 KW - Hematopoietic Stem Cell Transplantation KW - Hematopoietic Stem Cells KW - Humans KW - Liposomes KW - Receptors, CXCR4 KW - Recombinant Proteins KW - Transfection KW - Murinae AB - The chemokine stromal cell-derived factor (SDF)-1α/CXCL12 and its receptor CXC chemokine receptor 4 (CXCR4) play a crucial role in the homing/engraftment and retention of hematopoietic stem/progenitor cells (HSPCs) in the bone marrow. It has been shown using the viral gene transfer technique that CXCR4 overexpression on human CD34+ HSPC significantly improves their engraftment in murine models. However, clinical trials with gene therapy have revealed safety concerns related to the immunogenicity of the viral carriers, due to the random integration of viral genes into the host genome. Therefore, a method for CXCR4 gene delivery into HSPC that is safe, nonviral, and highly efficient is needed to improve clinical transplantation and gene therapies. In this work, we investigated the nonviral CXCR4 gene delivery into HSPC using the cationic liposome agent IBAfect. We used CD34+ cells from cord blood and the models of immature hematopoietic cells expressing CD34 antigen, namely, leukemic cell lines KG-1a and KG-1. Transfection efficiency was determined by flow cytometric analysis 12, 24, 48, and 72 h after transfection, and the viability of cells analyzed by trypan blue exclusion and MTS assays. The functional response of CXCR4-transfected HSPC toward an SDF-1α gradient was determined by chemotaxis assay. We found that ∼25% transfection is achieved for KG-1a and KG-1 cells and 20% for HSPC, and that the viability of CXCR4-transfected HSPC is not significantly altered. More importantly, overexpression of CXCR4 using IBAfect significantly increased the chemotaxis of KG-1 cells and HSPC toward SDF-1α. However, we tested 2 other commercially available cationic liposomes (Lipofectamine 2000 and 1,2-dioleoyl-3- trimethylammonium-propane [DOTAP]) in parallel, and we found that they failed to deliver the CXCR4 gene into cells under the same conditions. These results suggest that IBAfect-mediated in vitro gene delivery to overexpress CXCR4 on HSPC is a safe and efficient technique with great potential for improving the efficacy of HSPC transplantation and gene therapy protocols. DA - 2012/06/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 01bfbd84-f0c1-4233-a847-2ca85244fd4f ER - TY - JOUR TI - Wavefront sensing and correction with the Gemini Planet Imager DO - 10.1117/12.926680 AU - Thomas, S. AU - Poyneer, L. AU - Savransky, D. AU - Macintosh, B. AU - Hartung, M. AU - Dillon, D. AU - Gavel, D. AU - Dunn, Jennifer AU - Wallace, K. AU - Palmer, D. AU - De Rosa, Robert T2 - Adaptive Optics Systems III T2 - Proceedings of SPIE; 8447 T3 - Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491480 SP - 844714 KW - Adaptive optics systems KW - Aliasing KW - Calibration system KW - Contrast ratio KW - Deformable mirrors KW - Extra solar planets KW - Extrasolar planet detection KW - Extreme adaptive optics KW - High contrast imaging KW - High-accuracy KW - Image sharpening KW - MEMS deformable mirror KW - Shack-Hartmann wavefront sensors KW - Spatial filters KW - Sub-apertures KW - Temporal frequency KW - Wave-front sensing KW - Wavefront correction KW - Adaptive optics KW - Calibration KW - Instrument testing KW - Interferometry KW - Piezoelectric actuators KW - Wavefronts AB - High-contrast imaging is a growing observational technique aimed at discovering and characterizing extrasolar planets. The Gemini Planet Imager (GPI) is designed to achieve contrast ratios of 10-6 - 10 -7 and requires unprecedented wavefront correction and coronagraphic control of diffraction. GPI is a facility instrument now undergoing integration and testing and is scheduled for first light on the 8-m Gemini South telescope towards the end of 2012. In this paper, we focus on the wavefront sensing and correction aspects of the instrument. To measure the wavefront, GPI combines a Shack-Hartmann wavefront sensor and a high-accuracy infrared interferometric wavefront calibration system. The Shack-Hartmann wavefront sensor uses 1700 subapertures to precisely sample the wavefront at 1.5 kHz and features a spatial filter to prevent aliasing. The wavefront calibration system measures the slower temporal frequency errors as well as non-common path aberrations. The wavefront correction is performed using a two-stage adaptive optics system employing a 9x9 piezoelectric deformable mirror and a 43x43 actuators MEMS deformable mirror operating in a woofer-tweeter configuration. Finally, an image sharpening technique is used to further increase the contrast of the final image. In this paper, we describe the three wavefront sensing methods and how we combine their respective information to achieve the best possible contrast. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0e3914ba-405b-482e-ac68-c914650eeda9 ER - TY - JOUR TI - Assembly, integration, and verification (AIV) in ALMA: reries processing of array elements DO - 10.1117/12.925079 AU - Lopez, Bernhard AU - Jager, Rieks AU - Whyborn, Nicholas D. AU - Knee, Lewis B. G. AU - McMullin, Joseph P. T2 - Modeling, Systems Engineering, and Project Management for Astronomy V T2 - Proceedings of SPIE; 8449 T3 - Modeling, Systems Engineering, and Project Management for Astronomy V, July 1-3, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491503 SP - 84490P KW - Aperture synthesis KW - Atacama large millimeter/submillimeter array KW - East Asia KW - Joint projects KW - Matrix management KW - Millimeter wavelength KW - Project phasis KW - Series production KW - Telescope arrays KW - Assembly KW - Astronomy KW - Integration KW - Verification KW - Antennas AB - The Atacama Large Millimeter/submillimeter Array (ALMA) is a joint project between astronomical organizations in Europe, North America, and East Asia, in collaboration with the Republic of Chile. ALMA will consist of at least 54 twelve-meter antennas and 12 seven-meter antennas operating as an aperture synthesis array in the (sub)millimeter wavelength range. It is the responsibility of ALMA AIV to deliver the fully assembled, integrated, and verified antennas (array elements) to the telescope array. After an initial phase of infrastructure setup AIV activities began when the first ALMA antenna and subsystems became available in mid 2008. During the second semester of 2009 a project-wide effort was made to put in operation a first 3-antenna interferometer at the Array Operations Site (AOS). In 2010 the AIV focus was the transition from event-driven activities towards routine series production. Also, due to the ramp-up of operations activities, AIV underwent an organizational change from an autonomous department into a project within a strong matrix management structure. When the subsystem deliveries stabilized in early 2011, steady-state series processing could be achieved in an efficient and reliable manner. The challenge today is to maintain this production pace until completion towards the end of 2013. This paper describes the way ALMA AIV evolved successfully from the initial phase to the present steady-state of array element series processing. It elaborates on the different project phases and their relationships, presents processing statistics, illustrates the lessons learned and relevant best practices, and concludes with an outlook of the path towards completion. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 611349f4-e14b-4c96-a394-7d7f3a0b9e24 ER - TY - JOUR TI - Optical calibration and testing of the E-ELT M4 adaptive mirror DO - 10.1117/12.926008 AU - Spanò, P. AU - Bianco, A. AU - Briguglio, R. AU - Cecconi, M. AU - Miglietta, L. AU - Molinari, E. AU - Pariani, G. AU - Riccardi, A. AU - Riva, M. AU - Tresoldi, D. AU - Xompero, M. AU - Zerbi, F. T2 - Adaptive Optics Systems III T2 - Proceedings of SPIE; 8447 T3 - Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491480 SP - 84473O KW - Interferometry, CGH, stitching, piston sensor, ELTs AB - Innovative optical interferometry test setups and control software techniques have been proposed for the E-ELT M4 adaptive optics mirror. The system is composed of three sub-systems: a CGH-based optical test tower, delivering a 1.5-m collimated beam, for fast simultaneous acquisition of large areas; a stitching interferometer, to calibrate at higher spatial frequencies, on smaller areas; and an optical piston sensor to remove differential piston and tilt between adjacent mirror segments. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7887c254-b5c0-4fc9-9052-72eff4bdba09 ER - TY - JOUR TI - FLAMINGOS-2: the facility near-infrared wide-field imager and multi-object spectrograph for Gemini DO - 10.1117/12.925679 AU - Eikenberry, Stephen AU - Bandyopadhyay, Reba AU - Bennett, J. Greg AU - Bessoff, Aaron AU - Branch, Matt AU - Charcos, Miguel AU - Corley, Richard AU - Dewitt, Curtis AU - Eriksen, John-David AU - Elston, Richard AU - Frommeyer, Skip AU - Gonzalez, Anthony AU - Hanna, Kevin AU - Herlevich, Michael AU - Hon, David AU - Julian, Jeff AU - Julian, Roger AU - Lasso, Nestor AU - Marin-Franch, Antonio AU - Marti, Jose AU - Murphey, Charlie AU - Raines, S. N. AU - Rambold, William AU - Rashkin, David AU - Warner, Craig AU - Leckie, Brian AU - Gardhouse, W. R. AU - Fletcher, Murray AU - Hardy, Tim AU - Dunn, Jennifer AU - Wooff, Robert AU - Pazder, John T2 - Ground-based and Airborne Instrumentation for Astronomy IV T2 - Proceedings of SPIE; 8446 T3 - Ground-Based and Airborne Instrumentation for Astronomy IV, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491473 SP - 84460I KW - Band pass KW - Detector arrays KW - Field of views KW - High spatial resolution KW - Multi-conjugate adaptive optics systems KW - Multi-object spectrograph KW - Near Infrared KW - Wave front sensors KW - Wheel mechanism KW - Wide-field imager KW - Infrared devices KW - Optical systems KW - Spectrographs KW - Pixels AB - We report on the design, on-sky performance, and status of the FLAMINGOS-2 instrument - the fully-cryogenic facility near-infrared imager and multi-object spectrograph for the Gemini 8-meter telescopes. FLAMINGOS-2 has a refractive all-spherical optical system providing 0.18-arcsecond pixels and a 6.2-arcminute circular field-of-view on a 2048x2048-pixel HAWAII-2 0.9-2.4 μm detector array. A slit/decker wheel mechanism allows the selection of up to 9 multi-object laser-machined plates or 3 long slits for spectroscopy over a 6x2-arcminute field of view, and selectable grisms provide resolutions from ∼1300 to ∼3000 over the entire spectrograph bandpass. FLAMINGOS-2 is also compatible with the Gemini Multi-Conjugate Adaptive Optics system, providing multi-object spectroscopic capabilities over a 3x1-arcminute field with high spatial resolution (0.09-arcsec/pixel). We review the designs of optical, mechanical, electronics, software, and On-Instrument WaveFront Sensor subsystems. We also present the on-sky performance measured during acceptance testing in 2009, as well as current status of the project and future plans. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 30e64c97-3e3e-4514-bd21-587b80094ab0 ER - TY - JOUR TI - The Next Generation of the Canada-France-Hawaii Telescope: science requirements and survey strategies DO - 10.1117/12.926847 AU - McConnachie, Alan AU - Côté, Patrick AU - Crampton, David AU - Devost, Daniel AU - Simons, Doug AU - Szeto, Kei T2 - Ground-based and Airborne Telescopes IV T2 - Proceedings of SPIE; 8444 T3 - Ground-Based and Airborne Telescopes IV, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491459 SP - 84442Z KW - Dark energy KW - Galaxy evolution KW - Interstellar mediums KW - Milky way galaxy KW - Stellar astrophysics KW - Wavelength ranges KW - Wide field KW - Airborne telescopes KW - Optical telescopes KW - Spectroscopic analysis KW - Spectroscopy KW - Surveys KW - Galaxies AB - A concept study is underway to upgrade the existing 3.6 meter Canada-France-Hawaii Telescope (CFHT) to a 10 meter class, wide-field, dedicated, spectroscopic facility, which will be the sole astronomical resource capable of obtaining deep, spectroscopic follow-up data to the wealth of photometric and astrometric surveys planned for the next decade, and which is designed to tackle driving science questions on the formation of the Milky Way galaxy and the characterization and nature of dark energy. This unique facility will operate at low (R ∼ 2000), intermediate (R ∼ 6000) and high (R ∼ 20000) resolutions over the wavelength range 370 ≤ λ ≤ 1300nm, and will obtain up to 3200 simultaneous spectra per pointing over a 1.5 square degree field. Unlike all other proposed or planned wide field spectroscopic facilities, this "Next Generation CFHT" will combine the power of a 10m aperture with exquisite observing conditions and a mandate for dedicated spectroscopic studies to enable transformative science programs in fields as diverse as exoplanetary host characterization, the interstellar medium, stars and stellar astrophysics, the Milky Way galaxy, the Local Group, nearby galaxies and clusters, galaxy evolution, the inter-galactic medium, dark energy and cosmology. A new collaboration must be formed to make this necessary facility into a reality, and currently nearly 60 scientists from 11 different communities - Australia, Brazil, Canada, China, France, Hawaii, India, Japan, South Korea, Taiwan, USA - are involved in defining the science requirements and survey strategies. Here, we discuss the origins of this project, its motivations, the key science and its flow-down requirements. An accompanying article describes the technical studies completed to date. The final concept study will be submitted to the CFHT Board and Science Advisory Committee in Fall 2012, with first light for the facility aiming to be in the early 2020s. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d091aa42-2f1b-4dac-b311-04d4ca39390c ER - TY - JOUR TI - Performance of the integral field spectrograph for the Gemini Planet Imager DO - 10.1117/12.925790 AU - Chilcote, Jeffrey K. AU - Larkin, James E. AU - Maire, Jérôme AU - Perrin, Marshall D. AU - Fitzgerald, Michael P. AU - Doyon, René AU - Thibault, Simon AU - Bauman, Brian AU - Macintosh, Bruce A. AU - Graham, James R. AU - Saddlemyer, Les T2 - Ground-based and Airborne Instrumentation for Astronomy IV T2 - Proceedings of SPIE; 8446 T3 - Ground-Based and Airborne Instrumentation for Astronomy IV, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491473 SP - 84468W KW - Extra solar planets KW - Field of views KW - HAWAII-2RG KW - High quality KW - Integral field spectrograph KW - Jovian planets KW - Lawrence livermore national laboratories KW - Lenslet array KW - Noise source KW - Vibration isolations KW - Wollaston prism KW - Polarimeters AB - We present performance results, from in-lab testing, of the Integral Field Spectrograph (IFS) for the Gemini Planet Imager (GPI). GPI is a facility class instrument for the Gemini Observatory with the primary goal of directly detecting young Jovian planets. The GPI IFS is based on concepts from the OSIRIS instrument at Keck and utilizes an infrared transmissive lenslet array to sample a rectangular 2.8 x 2.8 arcsecond field of view. The IFS provides low-resolution spectra across five bands between 1 and 2.5 μm. Alternatively, the dispersing element can be replaced with a Wollaston prism to provide broadband polarimetry across the same five filter bands. The IFS construction was based at the University of California, Los Angeles in collaboration with the Université de Montréal, Immervision and Lawrence Livermore National Laboratory. During its construction, we encountered an unusual noise source from microphonic pickup by the Hawaii-2RG detector. We describe this noise and how we eliminated it through vibration isolation. The IFS has passed its preship review and was shipped to University of California, Santa Cruz at the end of 2011 for integration with the remaining sub-systems of GPI. The IFS has been integrated with the rest of GPI and is delivering high quality spectral datacubes of GPI's coronagraphic field. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6e3684b2-fa67-4444-b7a1-b48b2fa90aa1 ER - TY - JOUR TI - Interpretation of atomic motion in flexible molecules: accelerating molecular dynamics simulations DO - 10.1103/PhysRevE.85.026706 AU - Omelyan, Igor AU - Kovalenko, Andriy T2 - Physical Review E - Statistical, Nonlinear, and Soft Matter Physics SN - 1539-3755 VL - 85 IS - 2 SP - 26706 KW - Conformational properties KW - Coriolis KW - Femtoseconds KW - Molecular dynamics simulations KW - Multiple time step KW - Picoseconds KW - Time step KW - Translational degrees of freedoms KW - Vibrational components KW - Vibrational motions KW - Water models KW - Degrees of freedom (mechanics) KW - Kinetic energy KW - Molecular dynamics KW - Molecules KW - Atoms AB - We propose a new approach to split up the velocities of atoms of flexible molecules into translational, rotational, and vibrational components. As a result, the kinetic energy of the system can easily be expressed in terms of only three parts related to the above components. This is distinct from the standard Eckart method, where the cumbersome Coriolis contribution to the kinetic energy appears additionally. The absence of such a contribution within the proposed approach allows us to readily extend the microcanonical multiple-time-step dynamics of flexible molecules to the canonical-isokinetic Nosé-Hoover chain ensemble by explicitly integrating the translational, orientational, and vibrational motion. The previous extensions dealt exclusively with translational degrees of freedom of separate atoms, leading to a limitation on the size of the outer time step of 100 femtoseconds. We show on molecular dynamics simulations of the flexible TIP3P water model that the new canonical-isokinetic formulation gives a possibility to significantly overcome this limitation. In particular, huge outer time steps of order from a few hundred femtoseconds up to several picoseconds can now be employed to study conformational properties without loss of accuracy. DA - 2012/02/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 25a19bf1-b940-46a8-b61e-3eb8939911a2 ER - TY - JOUR TI - Nanoelectromechanical devices in a fluidic environment DO - 10.1103/PhysRevE.85.056313 AU - Svitelskiy, Oleksiy AU - Sauer, Vince AU - Vick, Douglass AU - Cheng, Kar-Mun AU - Liu, Ning AU - Freeman, Mark R. AU - Hiebert, Wayne K. T2 - Physical Review E - Statistical, Nonlinear, and Soft Matter Physics SN - 1539-3755 VL - 85 IS - 5 SP - 56313 KW - Fabrication technique KW - Fluid damping KW - High pressure KW - Intermediate pressures KW - Knudsen numbers KW - Lower pressures KW - Mass load KW - Mean free path KW - Micro resonators KW - Nano scale KW - Nanoresonators KW - Oscillation frequency KW - Phenomenological models KW - Pressure regime KW - Quality factors KW - Relaxation rates KW - Resonant response KW - Theoretical models KW - Weissenberg number KW - Nanotechnology KW - Damping AB - We present a comprehensive study of nanoelectromechanical systems in pressurized fluids. Resonant responses and quality factors are monitored in five different gases and one liquid, in pressures ranging from vacuum to 20 MPa, in order to evaluate theoretical models of device-fluid interactions at the nanoscale. The traditional Newell picture of microresonator damping in different pressure regimes is found to be inadequate in describing nanoresonators in general. Damping at intermediate pressure ranges is better physically characterized by a Weissenberg number (which compares oscillation frequencies with fluid relaxation rates) than a Knudsen number (which compares mean free paths with device widths) and most adequately described by the Yakhot and Colosqui model. At high-pressure ranges, two models are found to give good agreement with data: the phenomenological model of vibrating spheres and the Sader and Bhiladvala model for the viscous regime. The latter is also successful in explicitly predicting pressure-dependent behavior of the viscous mass load and damping. We observe significant increases in damping due to the squeezed film (SF) of gas between the device and substrate as well as due to undercut (an unavoidable artifact of the standard fabrication technique); correcting the shape of the devices with a focused ion beam allows us to differentiate these two factors. Application of the SF model accounts well for additional damping at high pressures while only qualitatively agreeing at lower pressures. The extensive data collected allow additional insight into fundamental processes underlying fluid damping at the nanoscale, particularly in the intermediate- and high-pressure regimes. DA - 2012/05/29 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9da3a372-d56a-4e6c-ae11-f2e8d2f5ec0a ER - TY - JOUR TI - Exploring the cell uptake mechanism of phospholipid and polyethylene glycol coated gold nanoparticles DO - 10.1088/0957-4484/23/4/045103 AU - Hao, Yuzhi AU - Yang, Xiaoyang AU - Song, Steven AU - Huang, Min AU - He, Chuan AU - Cui, Mingyang AU - Chen, Jie T2 - Nanotechnology SN - 0957-4484 VL - 23 IS - 4 SP - 45103 KW - Biodistributions KW - Biomedical applications KW - Cell uptake KW - In-vivo KW - Nanoparticle sizes KW - SEM and TEM KW - Sodium salt KW - Structural similarity KW - Biocompatibility KW - Cell membranes KW - Thermoplastics KW - Polyethylene glycols KW - 1 palmitoyl 2 oleoylglycero 3 phosphoglycerol KW - 1-palmitoyl-2-oleoylglycero-3-phosphoglycerol KW - macrogol derivative KW - metal nanoparticles KW - phosphatidylglycerol KW - cell death KW - drug effect KW - endocytosis KW - tumor cell line KW - ultrastructure KW - Phosphatidylglycerols KW - Polyethylene Glycols AB - Recently, there has been a lot of interest in using gold nanoparticles (GNPs) for biomedical applications due to their biocompatibility. To increase GNP cell uptake and circulation half-life, and to improve its bio-distribution invivo, we chose to coat GNPs with 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1- rac-glycerol) (sodium salt) (POPG) and polyethylene glycol (PEG). Two different methods were used to synthesize POPG-GNPs or PEG-GNPs, but the resulting nanoparticle sizes and morphologies were similar. Under the same incubation conditions, POPG-GNPs can be uptaken quicker than PEG-GNPs by cellsspecifically, the maximum uptake was 8h versus 16h after incubation. In addition, the uptake amount of POPG-GNPs was more than that of PEG-GNPs. The uptake processes were confirmed by SEM and TEM images. The main reason for the greater uptake of POPG-GNPs can be attributed to the structural similarities between the POPG coating and the cell membrane as well as GNP aggregation. DA - 2012/01/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 338e9260-03b5-4873-8840-694312fb157e ER - TY - JOUR TI - Indium tin oxide nanowhisker morphology control by vapour-liquid-solid glancing angle deposition DO - 10.1088/0957-4484/23/10/105608 AU - Beaudry, A. L. AU - Tucker, R. T. AU - Laforge, J. M. AU - Taschuk, M. T. AU - Brett, M. J. T2 - Nanotechnology SN - 0957-4484 VL - 23 IS - 10 SP - 105608 KW - Deposition angle KW - Feature sizes KW - Flux rates KW - Glancing angle deposition KW - Growth conditions KW - Growth flux KW - Growth techniques KW - High surface area KW - Indium tin oxide KW - Morphology control KW - Nanostructured Films KW - Spatial modulations KW - Substrate temperature KW - Transparent conductive KW - Transparent conductive oxides KW - VLS growth KW - Crystal whiskers KW - Indium compounds KW - Liquids KW - Morphology KW - Nanowhiskers KW - Tin KW - Tin oxides KW - Conductive films AB - A new growth technique for indium tin oxide nanowhiskers with increased control over feature size and spacing is reported. The technique is based on a unique combination of self-catalysed vapour-liquid-solid (VLS) growth and glancing angle deposition (GLAD). This VLSGLAD technique provides enhanced control over nanowhisker morphology as the effect of typical VLS growth parameters (e.g.flux rate, temperature) is amplified at large deposition angles characteristic of GLAD. Spatial modulation of the collimated growth flux controls trunk width, number and orientation of branches, and overall nanowhisker density. Here we report the influence of growth conditions (including deposition angle, flux rate, nominal pitch and substrate temperature) on nanowhisker morphology, with specific focus on the effect of large deposition angles. Sheet resistance and transmission of the films were measured to characterize their performance as transparent conductive oxides. Hybrid nanostructured films grown in this study include high surface area nanowhiskers protruding from a conductive film, ideal for transparent conductive electrode applications. DA - 2012/02/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3f43b6ab-5ae0-4b8f-9adb-11b5d4916550 ER - TY - JOUR TI - Reactive fillers based on SWCNTs functionalized with matrix-based moieties for the production of epoxy composites with superior and tunable properties DO - 10.1088/0957-4484/23/28/285702 AU - González-Domínguez, Jose M. AU - Martínez-Rubí, Yadienka AU - Díez-Pascual, Ana M. AU - Ansón-Casaos, A. AU - Gómez-Fatou, Marian AU - Simard, Benoit AU - Martínez, M. Teresa T2 - Nanotechnology SN - 0957-4484 VL - 23 IS - 28 SP - 285702 KW - Chemical affinities KW - Covalent functionalizations KW - Degradation temperatures KW - Electrical conductivity KW - Epoxy composite KW - Epoxy matrices KW - Functionalizations KW - Functionalized KW - Grafted moieties KW - Interfacial bonding KW - Reactive fillers KW - Thermal Performance KW - Tunable properties KW - Electric conductivity KW - Loading KW - Physical properties KW - Single-walled carbon nanotubes (SWCN) KW - Fillers AB - Composite materials based on epoxy matrix and single-walled carbon nanotubes (SWCNTs) are able to exhibit outstanding improvements in physical properties when using a tailored covalent functionalization with matrix-based moieties containing terminal amines or epoxide rings. The proper choice of grafted moiety and integration protocol makes it feasible to tune the composite physical properties. At 0.5wt% SWCNT loading, these composites exhibit up to 65% improvement in storage modulus, 91% improvement in tensile strength, and 65% improvement in toughness. A 15°C increase in the glass transition temperature relative to the parent matrix was also achieved. This suggests that a highly improved interfacial bonding between matrix and filler, coupled to improved dispersion, are achieved. The degradation temperatures show an upshift in the range of 4060°C, which indicates superior thermal performance. Electrical conductivity ranges from 10 13 to 10 3Scm 1, which also shows the possibility of tuning the insulating or conductive behaviour of the composites. The chemical affinity of the functionalization moieties with the matrix and the unchanged molecular structure at the SWCNT/matrix interface are responsible for such improvements. DA - 2012/06/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e8f5e341-e7df-4eee-98c2-9635f8f5eca6 ER - TY - JOUR TI - Pharmacokinetic and toxicological evaluation of multi-functional thiol-6-fluoro-6-deoxy-d-glucose gold nanoparticles in vivo DO - 10.1088/0957-4484/23/37/375101 AU - Roa, Wilson AU - Xiong, Yeping AU - Chen, Jie AU - Yang, Xiaoyan AU - Song, Kun AU - Yang, Xiaohong AU - Kong, Beihua AU - Wilson, John AU - Xing, James Z. T2 - Nanotechnology SN - 0957-4484 VL - 23 IS - 37 SP - 375101 AB - We synthesized a novel, multi-functional, radiosensitizing agent by covalently linking 6-fluoro-6-deoxy-d-glucose (6-FDG) to gold nanoparticles (6-FDG-GNPs) via a thiol functional group. We then assessed the bio-distribution and pharmacokinetic properties of 6-FDG-GNPs in vivo using a murine model. At 2h, following intravenous injection of 6-FDG-GNPs into the murine model, approximately 30% of the 6-FDG-GNPs were distributed to three major organs: the liver, the spleen and the kidney. PEGylation of the 6-FDG-GNPs was found to significantly improve the bio-distribution of 6-FDG-GNPs by avoiding unintentional uptake into these organs, while simultaneously doubling the cellular uptake of GNPs in implanted breast MCF-7 adenocarcinoma. When combined with radiation, PEG-6-FDG-GNPs were found to increase the apoptosis of the MCF-7 breast adenocarinoma cells by radiation both in vitro and in vivo. Pharmacokinetic data indicate that GNPs reach their maximal concentrations at a time window of two to four hours post-injection, during which optimal radiation efficiency can be achieved. PEG-6-FDG-GNPs are thus novel nanoparticles that preferentially accumulate in targeted cancer cells where they act as potent radiosensitizing agents. Future research will aim to substitute the 18F atom into the 6-FDG molecule so that the PEG-6-FDG-GNPs can also function as radiotracers for use in positron emission tomography scanning to aid cancer diagnosis and image guided radiation therapy planning. DA - 2012/08/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ed83741b-420a-4787-ae8b-d910825b29a3 ER - TY - JOUR TI - Spatial matter density mapping of the STAGES Abell A901/2 supercluster field with 3D lensing DO - 10.1111/j.1365-2966.2011.19760.x AU - Simon, P. AU - Heymans, C. AU - Schrabback, T. AU - Taylor, A. N. AU - Gray, M. E. AU - van Waerbeke, L. AU - Wolf, C. AU - Bacon, D. AU - Barden, M. AU - Böhm, A. AU - Häußler, B. AU - Jahnke, K. AU - Jogee, S. AU - van Kampen, E. AU - Meisenheimer, K. AU - Peng, C. Y. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 419 IS - 2 SP - 998 EP - 1016 AB - We present weak lensing data from the Hubble Space Telescope(HST)/Space Telescope A901/902 Galaxy Evolution Survey (STAGES) survey to study the three-dimensional spatial distribution of matter and galaxies in the Abell 901/902 supercluster complex. Our method improves over the existing 3D lensing mapping techniques by calibrating and removing redshift bias and accounting for the effects of the radial elongation of 3D structures. We also include the first detailed noise analysis of a 3D lensing map, showing that even with deep HST-quality data, only the most massive structures, for example M 200≳ 10 15M ⊙h -1 at z∼ 0.8, can be resolved in 3D with any reasonable redshift accuracy (Δz≈ 0.15). We compare the lensing map to the stellar mass distribution and find luminous counterparts for all mass peaks detected with a peak significance >3σ. We see structures in and behind the z= 0.165 foreground supercluster, finding structure directly behind the A901b cluster at z∼ 0.6 and also behind the south-west (SW) group at z∼ 0.7. This 3D structure viewed in projection has no significant impact on recent mass estimates of A901b or the SW group components SWa and SWb. DA - 2012/01/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 319b100b-7aec-41a4-adbb-4e2cec9d8cb4 ER - TY - JOUR TI - The star formation history and dust content in the far outer disc of M31 DO - 10.1111/j.1365-2966.2011.20234.x AU - Bernard, Edouard J. AU - Ferguson, Annette M. N. AU - Barker, Michael K. AU - Hidalgo, Sebastien L. AU - Ibata, Rodrigo A. AU - Irwin, Michael J. AU - Lewis, Geraint F. AU - McConnachie, Alan W. AU - Monelli, Matteo AU - Chapman, Scott C. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 420 IS - 3 SP - 2625 EP - 2643 AB - We present a detailed analysis of two fields located 26kpc (∼5 radial scalelengths) from the centre of M31 along the south-west semimajor axis of the disc. One field samples the major axis populations - the Outer Disc field - while the other is offset by ∼18arcmin and samples the warp in the stellar disc - the warp field. The colour-magnitude diagrams (CMDs) based on Hubble Space Telescope Advanced Camera for Surveys imaging reach old main-sequence turn-offs (∼12.5Gyr). We apply the CMD-fitting technique to the warp field to reconstruct the star formation history (SFH). We find that after undergoing roughly constant star formation until about 4.5Gyr ago, there was a rapid decline in activity and then a ∼1.5Gyr lull, followed by a strong burst lasting 1.5Gyr and responsible for 25 per cent of the total stellar mass in this field. This burst appears to be accompanied by a decline in global metallicity which could be a signature of the inflow of metal-poor gas. The onset of the burst (∼3Gyr ago) corresponds to the last close passage of M31 and M33 as predicted by detailed N-body modelling, and may have been triggered by this event. We reprocess the deep M33 outer disc field data of Barker et al. in order to compare consistently derived SFHs. This reveals a similar duration burst that is exactly coeval with that seen in the M31 warp field, lending further support to the interaction hypothesis. We reliably trace star formation as far back as 12-13Gyr ago in the outer disc of M31, while the onset of star formation occurred about 2Gyr later in M33, with median stellar ages of 7.5 and 4.5Gyr, respectively. The complex SFHs derived, as well as the smoothly varying age-metallicity relations, suggest that the stellar populations observed in the far outer discs of both galaxies have largely formed in situ rather than migrated from smaller galactocentric radii. The strong differential reddening affecting the CMD of the Outer Disc field prevents derivation of the SFH using the same method. Instead, we quantify this reddening and find that the fine-scale distribution of dust precisely follows that of the Hi gas. This indicates that the outer Hi disc of M31 contains a substantial amount of dust and therefore suggests significant metal enrichment in these parts, consistent with inferences from our CMD analysis. DA - 2012/03/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cbd63517-2399-4ef8-a0eb-186bac8471c4 ER - TY - JOUR TI - Variable stars in the Cetus dwarf spheroidal galaxy: population gradients and connections with the star formation history DO - 10.1111/j.1365-2966.2012.20539.x AU - Monelli, M. AU - Bernard, E. J. AU - Gallart, C. AU - Fiorentino, G. AU - Drozdovsky, I. AU - Aparicio, A. AU - Bono, G. AU - Cassisi, S. AU - Skillman, E. D. AU - Stetson, P. B. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 422 IS - 1 SP - 89 EP - 105 AB - We investigate the variable star content of the isolated, Local Group, dwarf spheroidal (dSph) galaxy Cetus. Multi-epoch, wide-field images collected with the Very Large Telescope/Visible Multiobject Spectrograph camera allowed us to detect 638 variable stars (630 RRLyrae stars and eight anomalous Cepheids), 475 of which are new detections. We present a full catalogue of periods, amplitudes and mean magnitudes. Motivated by the recent discovery that the pulsational properties of the RRLyrae stars in the Tucana dSph revealed the presence of a metallicity gradient within the oldest (>rsim10Gyr old) stellar populations, we investigated the possibility of an analogous effect in Cetus. We found that, despite the obvious radial gradient in the horizontal branch and red giant branch morphologies, both becoming bluer on average for increasing distance from the centre of Cetus, the properties of the RRLyrae stars are homogeneous within the investigated area (out to r∼ 15arcmin), with no significant evidence of a radial gradient. We discuss this in connection with the star formation history previously derived for the two galaxies. The observed differences between these two systems show that even systems this small show a variety of early evolutionary histories. These differences could be due to different merger or accretion histories. DA - 2012/05/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e8f68027-1dd5-4593-a919-b10f59efe1d8 ER - TY - JOUR TI - The structure of star clusters in the outer halo of M31 DO - 10.1111/j.1365-2966.2012.20590.x AU - Tanvir, N. R. AU - Mackey, A. D. AU - Ferguson, A. M. N. AU - Huxor, A. AU - Read, J. I. AU - Lewis, G. F. AU - Irwin, M. J. AU - Chapman, S. AU - Ibata, R. AU - Wilkinson, M. I. AU - McConnachie, A. W. AU - Martin, N. F. AU - Davies, M. B. AU - Bridges, T. J. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 422 IS - 1 SP - 162 EP - 184 AB - We present a structural analysis of halo star clusters in M31 based on deep Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) imaging. The clusters in our sample span a range in galactocentric projected distance from 13 to 100kpc and thus reside in rather remote environments. Ten of the clusters are classical globulars, whilst four are from the Huxor et al. population of extended, old clusters. For most clusters, contamination by M31 halo stars is slight, and so the profiles can be mapped reliably to large radial distances from their centres. We find that the extended clusters are well fit by analytic King profiles with ∼20 parsec core radii and ∼100 parsec photometric tidal radii, or by Sérsic profiles of index ∼1 (i.e. approximately exponential). Most of the classical globulars also have large photometric tidal radii in the range 50-100 parsec; however, the King profile is a less good fit in some cases, particularly at small radii. We find 60 percent of the classical globular clusters exhibit cuspy cores which are reasonably well described by Sérsic profiles of index ∼2-6. Our analysis also reinforces the finding that luminous classical globulars, with half-light radii <10 parsec, are present out to radii of at least 100kpc in M31, which is in contrast to the situation in the Milky Way where such clusters (other than the unusual object NGC 2419) are absent beyond 40kpc. DA - 2012/05/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a1ba685f-71d4-4e5a-8e39-f7f86d32f70b ER - TY - JOUR TI - GALAPAGOS: from pixels to parameters DO - 10.1111/j.1365-2966.2012.20619.x AU - Barden, Marco AU - Häußler, Boris AU - Peng, Chien Y. AU - McIntosh, Daniel H. AU - Guo, Yicheng T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 422 IS - 1 SP - 449 EP - 468 AB - To automate source detection, two-dimensional light profile Sérsic modelling and catalogue compilation in large survey applications, we introduce a new code Galaxy Analysis over Large Areas: Parameter Assessment by galfitting Objects from SExtractor (galapagos). Based on a single set-up, galapagos can process a complete set of survey images. It detects sources in the data, estimates a local sky background, cuts postage stamp images for all sources, prepares object masks, performs Sérsic fitting including neighbours and compiles all objects in a final output catalogue. For the initial source detection, galapagos applies SExtractor, while galfit is incorporated for modelling Sérsic profiles. It measures the background sky involved in the Sérsic fitting by means of a flux growth curve. galapagos determines postage stamp sizes based on SExtractor shape parameters. In order to obtain precise model parameters, galapagos incorporates a complex sorting mechanism and makes use of modern CPU's multiplexing capabilities. It combines SExtractor and galfit data in a single output table. When incorporating information from overlapping tiles, galapagos automatically removes multiple entries from identical sources. galapagos is programmed in the Interactive Data Language (idl). We test the stability and the ability to properly recover structural parameters extensively with artificial image simulations. Moreover, we apply galapagos successfully to the STAGES data set. For one-orbit Hubble Space Telescope data, a single 2.2-GHz CPU processes about 1000 primary sources per 24h. Note that galapagos results depend critically on the user-defined parameter set-up. This paper provides useful guidelines to help the user make sensible choices. DA - 2012/05/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1c5af202-9152-42f7-87d6-c3916bcbe0dc ER - TY - JOUR TI - Magnetic field, differential rotation and activity of the hot-Jupiter-hosting star HD 179949 DO - 10.1111/j.1365-2966.2012.20780.x AU - Fares, R. AU - Donati, J.-F. AU - Moutou, C. AU - Jardine, M. AU - Cameron, A. C. AU - Lanza, A. F. AU - Bohlender, D. AU - Dieters, S. AU - Martínez Fiorenzano, A. F. AU - Maggio, A. AU - Pagano, I. AU - Shkolnik, E. L. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 423 IS - 2 SP - 1006 EP - 1017 AB - HD 179949 is an F8V star, orbited by a giant planet at ∼8 R{black star} every 3.092514 d. The system was reported to undergo episodes of stellar activity enhancement modulated by the orbital period, interpreted as caused by star-planet interactions (SPIs). One possible cause of SPIs is the large-scale magnetic field of the host star in which the close-in giant planet orbits. In this paper we present spectropolarimetric observations of HD 179949 during two observing campaigns (2009 September and 2007 June). We detect a weak large-scale magnetic field of a few gauss at the surface of the star. The field configuration is mainly poloidal at both observing epochs. The star is found to rotate differentially, with a surface rotation shear of dΩ= 0.216 ± 0.061 rad d-¹, corresponding to equatorial and polar rotation periods of 7.62 ± 0.07 and 10.3 ± 0.8d, respectively. The coronal field estimated by extrapolating the surface maps resembles a dipole tilted at ∼70°. We also find that the chromospheric activity of HD 179949 is mainly modulated by the rotation of the star, with two clear maxima per rotation period as expected from a highly tilted magnetosphere. In 2009 September, we find that the activity of HD 179949 shows hints of low-amplitude fluctuations with a period close to the beat period of the system. DA - 2012/06/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a6bfcb0f-e60e-4163-b27f-25ca6512ff54 ER - TY - JOUR TI - The Volume-limited A-Star (VAST) survey - II. Orbital motion monitoring of A-type star multiples DO - 10.1111/j.1365-2966.2011.20397.x AU - De Rosa, R. J. AU - Patience, J. AU - Vigan, A. AU - Wilson, P. A. AU - Schneider, A. AU - Mcconnell, N.J. AU - Wiktorowicz, S. J. AU - Marois, C. AU - Song, I. AU - Macintosh, B. AU - Graham, J. R. AU - Bessell, M. S. AU - Doyon, R. AU - Lai, O. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 422 IS - 4 SP - 2765 EP - 2785 AB - As a part of our ongoing Volume-limited A-Star (VAST) adaptive optics survey, we have obtained observations of 26 binary systems with projected separations <100 au, 13 of which have sufficient historical measurements to allow for refinement of their orbital elements. For each system with an estimated orbit, the dynamical system mass obtained was compared with the system mass estimated from mass-magnitude relations. Discrepancies between the dynamical and theoretical system mass can be explained by the presence of a previously unresolved spectroscopic component or by a non-solar metallicity of the system. Using this approach to infer the presence of additional companions, a lower limit to the fraction of binaries, triples and quadruples can be estimated as 39, 46 and 15per cent for systems with at least one companion within 100 au. The fraction of multiple systems with three or more components shows a relative increase compared to the fraction for solar-type primaries resolved in previous volume-limited surveys. The observations have also revealed a pair of potentially young (<100Myr) M dwarf companions, which would make an ideal benchmark for the theoretical models during the pre-main-sequence contraction phase for M dwarfs. In addition to those systems with orbit fits, we report 13 systems for which further orbital monitoring observations are required, 11 of which are newly resolved as a part of the VAST survey. DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8a883d51-02fa-46c4-9581-802a675808cb ER - TY - JOUR TI - Herschel imaging of 61Vir: implications for the prevalence of debris in low-mass planetary systems DO - 10.1111/j.1365-2966.2012.21298.x AU - Wyatt, M. C. AU - Kennedy, G. AU - Sibthorpe, B. AU - Moro-Martín, A. AU - Lestrade, J.-F. AU - Ivison, R.J. AU - Matthews, B. AU - Udry, S. AU - Greaves, J. S. AU - Kalas, P. AU - Lawler, S. AU - Su, K. Y. L. AU - Rieke, G. H. AU - Booth, M. AU - Bryden, G. AU - Horner, J. AU - Kavelaars, J. J. AU - Wilner, D. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 424 IS - 2 SP - 1206 EP - 1223 AB - This paper describes Herschel observations of the nearby (8.5pc) G5V multi-exoplanet host star 61Vir at 70, 100, 160, 250, 350 and 500m carried out as part of the DEBRIS survey. These observations reveal emission that is significantly extended out to a distance of >15arcsec with a morphology that can be fitted by a nearly edge-on (77° inclination) radially broad (from 30au out to at least 100au) debris disc of fractional luminosity 2.7 × 10^-5, with two additional (presumably unrelated) sources nearby that become more prominent at longer wavelengths. Chance alignment with a background object seen at 1.4GHz provides potential for confusion, however, the star's 1.4 arcsec yr-¹ proper motion allows archival Spitzer 70m images to confirm that what we are interpreting as disc emission really is circumstellar. Although the exact shape of the disc's inner edge is not well constrained, the region inside 30au must be significantly depleted in planetesimals. This is readily explained if there are additional planets outside those already known (i.e. in the 0.5-30au region), but is also consistent with collisional erosion. We also find tentative evidence that the presence of detectable debris around nearby stars correlates with the presence of the lowest mass planets that are detectable in current radial velocity surveys. Out of an unbiased sample of the nearest 60G stars, 11 are known to have planets, of which six (including 61Vir) have planets that are all less massive than Saturn, and four of these have evidence for debris. The debris towards one of these planet hosts (HD20794) is reported here for the first time. This fraction (4/6) is higher than that expected for nearby field stars (15per cent), and implies that systems that form low-mass planets are also able to retain bright debris discs. We suggest that this correlation could arise because such planetary systems are dynamically stable and include regions that are populated with planetesimals in the formation process where the planetesimals can remain unperturbed over Gyr time-scales. DA - 2012/08/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ab6209fe-0939-41bf-bbe9-a25d746e80ce ER - TY - JOUR TI - Theoretical investigation of planar square carbon allotrope and its hydrogenation DO - 10.1088/0953-8984/24/17/175501 AU - Pujari, Bhalchandra S. AU - Tokarev, Andrey AU - Saraf, Deepashri A. T2 - Journal of Physics: Condensed Matter SN - 0953-8984 VL - 24 IS - 17 SP - 175501 AB - Using density functional theory we investigate a novel carbon allotrope SqC: a square planar material that can be more than tetracoordinated. Carbon atoms in this 2D square Bravais lattice form an unusual five-center four-electron bond with neighboring four carbon atoms (tetracoordination). Such an electron-deficient bonding leaves an empty orbital which enables penta- or hexa-coordinated carbon atom. Indeed, our simulations demonstrate such penta- and hexa-coordinated configurations upon partial and complete hydrogenation, respectively. Surprisingly, in all the forms SqC shows the metallic character. SqC has the binding energy of 6.7eV and it also satisfies the Born stability criteria. Yet our phonon calculations show that it may only be considered as quasi-stable. DA - 2012/04/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0b565d49-31ce-4dc6-9b48-96ffb6c9f6b9 ER - TY - JOUR TI - Testing the limits: America's Cup performance evaluations AU - Pallard, Robert T2 - Journal of Ocean Technology SN - 1718-3200 VL - 7 IS - 1 SP - 1 EP - 8 AB - The National Research Council-Institute for Ocean Technology (NRC-IOT) is Canada's national centre for ocean technology research and development. It was established in 1985 to support the development of innovative technologies in the private sector and to assist oceans-related public initiatives. The Institute's capability is unique to the nation - no other organization offers the combination of knowledge, experience and world-class facilities. Research is conducted on technologies for use in ocean observation, marine safety, Arctic operations and performance evaluation. Major facilities operated by the Institute include a 200-metre Towing Tank, a 75-metre by 32-metre Offshore Engineering Basin, and a 90-metre Ice Tank, the longest in the world. In this essay, author Robert Pallard talks about America's Cup testing that took place at the Institute over a 16-year period. DA - 2012/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fb6aeecf-2d3f-4b9c-8155-be4d231ac9e5 ER - TY - JOUR TI - Infrared spectroscopy of nearby radio active elliptical galaxies DO - 10.1088/0067-0049/203/1/14 AU - Mould, Jeremy AU - Reynolds, Tristan AU - Readhead, Tony AU - Floyd, David AU - Jannuzi, Buell AU - Cotter, Garret AU - Ferrarese, Laura AU - Matthews, Keith AU - Atlee, David AU - Brown, Michael T2 - The Astrophysical Journal: Supplement Series SN - 0067-0049 VL - 203 IS - 1 SP - 14 AB - In preparation for a study of their circumnuclear gas we have surveyed 60% of a complete sample of elliptical galaxies within 75 Mpc that are radio sources. Some 20% of our nuclear spectra have infrared emission lines, mostly Paschen lines, Brackett γ, and [Fe II]. We consider the influence of radio power and black hole mass in relation to the spectra. Access to the spectra is provided here as a community resource. DA - 2012/11/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3edb2d7e-7b6e-43ee-b4ce-274e3c65905b ER - TY - JOUR TI - Discovery of the host cluster for the fundamental Cepheid calibrator zeta Geminorum DO - 10.1088/2041-8205/748/1/L9 AU - Majaess, D. AU - Turner, D. AU - Gieren, W. AU - Balam, D. AU - Lane, D. T2 - The Astrophysical Journal Letters SN - 2041-8205 VL - 748 IS - 1 SP - L9 AB - New and existing CORAVEL, UBVJHKs, HST, HIP/Tycho, ARO, KPNO, and DAO observations imply that the fundamental Cepheid calibrator ζ Gem is a cluster member. The following parameters were inferred for ζGem from cluster membership and are tied to new spectral classifications (DAO) established for 26 nearby stars (e.g., HD53588/B7.5IV, HD54692/B9.5IV): E B-V = 0.02 ± 0.02, log τ = 7.85 ± 0.15, and d = 355 ± 15 pc. The mean distance to ζ Gem from cluster membership and six recent estimates (e.g., IRSB) is d=363 ± 9(σx)±26(σ) pc. The results presented here support the color-excess and HST parallax derived for the Cepheid by Benedict et al. Forthcoming precise proper motions (DASCH) and Chandra/XMM-Newton observations of the broader field may be employed to identify cluster members, bolster the cluster's existence, and provide stronger constraints on the Cepheid's fundamental parameters. © 2012. The American Astronomical Society. All rights reserved. DA - 2012/02/28 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 348da5c9-c950-42d4-bc90-f15ac176676a ER - TY - JOUR TI - Molecular tracers of turbulent shocks in giant molecular clouds DO - 10.1088/0004-637X/748/1/25 AU - Pon, A. AU - Johnstone, D. AU - Kaufman, M. J. T2 - The Astrophysical Journal SN - 0004-637X VL - 748 IS - 1 SP - 25 AB - Giant molecular clouds contain supersonic turbulence and simulations of magnetohydrodynamic turbulence show that these supersonic motions decay in roughly a crossing time, which is less than the estimated lifetimes of molecular clouds. Such a situation requires a significant release of energy. We run models of C-type shocks propagating into gas with densities around 10 3cm -3 at velocities of a fewkms -1, appropriate for the ambient conditions inside of a molecular cloud, to determine which species and transitions dominate the cooling and radiative energy release associated with shock cooling of turbulent molecular clouds. We find that these shocks dissipate their energy primarily through CO rotational transitions and by compressing pre-existing magnetic fields. We present model spectra for these shocks, and by combining these models with estimates for the rate of turbulent energy dissipation, we show that shock emission should dominate over emission from unshocked gas for mid to high rotational transitions (J > 5) of CO. We also find that the turbulent energy dissipation rate is roughly equivalent to the cosmic-ray heating rate and that the ambipolar diffusion heating rate may be significant, especially in shocked gas. DA - 2012/03/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4a44fc4d-57eb-4dbe-b2a5-e26c888cb033 ER - TY - JOUR TI - The resolved structure and dynamics of an isolated dwarf galaxy: a VLT and Keck spectroscopic survey of WLM DO - 10.1088/0004-637X/750/1/33 AU - Leaman, Ryan AU - Venn, Kim A. AU - Brooks, Alyson M. AU - Battaglia, Giuseppina AU - Cole, Andrew A. AU - Ibata, Rodrigo A. AU - Irwin, Mike J. AU - McConnachie, Alan W. AU - Mendel, J. Trevor AU - Tolstoy, Eline T2 - The Astrophysical Journal SN - 0004-637X VL - 750 IS - 1 SP - 33 AB - We present spectroscopic data for 180 red giant branch (RGB) stars in the isolated dwarf irregular galaxy Wolf-Lundmark-Mellote (WLM). Observations of the calcium II triplet lines in spectra of RGB stars covering the entire galaxy were obtained with FORS2 at the Very Large Telescope and DEIMOS on Keck II, allowing us to derive velocities, metallicities, and ages for the stars. With accompanying photometric and radio data we have measured the structural parameters of the stellar and gaseous populations over the full galaxy. The stellar populations show an intrinsically thick configuration with 0.39 ≤ q 0 ≤ 0.57. The stellar rotation in WLM is measured to be 17 ± 1 km s-¹; however, the ratio of rotation to pressure support for the stars is V/σ 1, in contrast to the gas, whose ratio is seven times larger. This, along with the structural data and alignment of the kinematic and photometric axes, suggests we are viewing WLM as a highly inclined oblate spheroid. Stellar rotation curves, corrected for asymmetric drift, are used to compute a dynamical mass of (4.3 ± 0.3) × 10^8 M ☉ at the half-light radius (r h = 1656 ± 49pc). The stellar velocity dispersion increases with stellar age in a manner consistent with giant molecular cloud and substructure interactions producing the heating in WLM. Coupled with WLM's isolation, this suggests that the extended vertical structure of its stellar and gaseous components and increase in stellar velocity dispersion with age are due to internal feedback, rather than tidally driven evolution. These represent some of the first observational results from an isolated Local Group dwarf galaxy that can offer important constraints on how strongly internal feedback and secular processes modulate star formation and dynamical evolution in low-mass isolated objects. © 2012 The American Astronomical Society. All rights reserved. DA - 2012/04/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 82e21769-4e65-4c9b-bba9-28fbbdba71cc ER - TY - JOUR TI - Anchoring the distance scale VIA X-ray/infrared data for Cepheid clusters: SU Cas DO - 10.1088/0004-637X/753/2/144 AU - Majaess, D. AU - Turner, D. G. AU - Gallo, L. AU - Gieren, W. AU - Bonatto, C. AU - Lane, D.J. AU - Balam, D. AU - Berdnikov, L. T2 - The Astrophysical Journal SN - 0004-637X VL - 753 IS - 2 SP - 144 AB - New X-ray (XMM-Newton) and JHK s (Observatoire du Mont-Mégantic) observations for members of the star cluster Alessi 95, which Turner etal. discovered hosts the classical Cepheid SU Cas, were used in tandem with UCAC3 (proper motion) and Two Micron All Sky Survey observations to determine precise cluster parameters: E(J - H) = 0.08 ± 0.02 and d = 405 ± 15 pc. The ensuing consensus among cluster, pulsation, and trigonometric distances (d=414±5((σx)±10((σ) pc) places SU Cas in a select group of nearby fundamental Cepheid calibrators (δ Cep, ζ Gem). High-resolution X-ray observations may be employed to expand that sample as the data proved pertinent for identifying numerous stars associated with SU Cas. Acquiring X-ray observations of additional fields may foster efforts to refine Cepheid calibrations used to constrain H 0. DA - 2012/06/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 96c7c9a1-6f64-4400-9420-0d16838c30d1 ER - TY - JOUR TI - Aspect ratio dependence of the free-fall time for non-spherical symmetries DO - 10.1088/0004-637X/756/2/145 AU - Pon, Andy AU - Toalá, Jesús A. AU - Johnstone, Doug AU - Vázquez-Semadeni, Enrique AU - Heitsch, Fabian AU - Gómez, Gilberto C. T2 - The Astrophysical Journal SN - 0004-637X VL - 756 IS - 2 SP - 145 KW - ISM: clouds; ISM: structure; stars: formation AB - We investigate the collapse of non-spherical substructures, such as sheets and filaments, which are ubiquitous in molecular clouds. Such non-spherical substructures collapse homologously in their interiors but are influenced by an edge effect that causes their edges to be preferentially accelerated. We analytically compute the homologous collapse timescales of the interiors of uniform-density, self-gravitating filaments and find that the homologous collapse timescale scales linearly with the aspect ratio. The characteristic timescale for an edge-driven collapse mode in a filament, however, is shown to have a square-root dependence on the aspect ratio. For both filaments and circular sheets, we find that selective edge acceleration becomes more important with increasing aspect ratio. In general, we find that lower dimensional objects and objects with larger aspect ratios have longer collapse timescales. We show that estimates for star formation rates, based upon gas densities, can be overestimated by an order of magnitude if the geometry of a cloud is not taken into account. DA - 2012/08/23 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c255f487-b792-4a98-9dd8-fd23909f4b90 ER - TY - JOUR TI - A Bayesian approach to locating the red giant branch tip magnitude. II. Distances to the satellites of M31 DO - 10.1088/0004-637X/758/1/11 AU - Conn, A. R. AU - Ibata, R. A. AU - Lewis, G. F. AU - Parker, Q. A. AU - Zucker, D. B. AU - Martin, N. F. AU - McConnachie, A. W. AU - Irwin, M. J. AU - Tanvir, N. AU - Fardal, M. A. AU - Ferguson, A. M. N. AU - Chapman, S. C. AU - Valls-Gabaud, D. T2 - The Astrophysical Journal SN - 0004-637X VL - 758 IS - 1 SP - 11 AB - In "A Bayesian Approach to Locating the Red Giant Branch Tip Magnitude (Part I)," a new technique was introduced for obtaining distances using the tip of the red giant branch (TRGB) standard candle. Here we describe a useful complement to the technique with the potential to further reduce the uncertainty in our distance measurements by incorporating a matched-filter weighting scheme into the model likelihood calculations. In this scheme, stars are weighted according to their probability of being true object members. We then re-test our modified algorithm using random-realization artificial data to verify the validity of the generated posterior probability distributions (PPDs) and proceed to apply the algorithm to the satellite system of M31, culminating in a three-dimensional view of the system. Further to the distributions thus obtained, we apply a satellite-specific prior on the satellite distances to weight the resulting distance posterior distributions, based on the halo density profile. Thus in a single publication, using a single method, a comprehensive coverage of the distances to the companion galaxies of M31 is presented, encompassing the dwarf spheroidals Andromedas I-III, V, IX-XXVII, and XXX along with NGC147, NGC185, M33, and M31 itself. Of these, the distances to Andromedas XXIV-XXVII and Andromeda XXX have never before been derived using the TRGB. Object distances are determined from high-resolution tip magnitude posterior distributions generated using the Markov Chain Monte Carlo technique and associated sampling of these distributions to take into account uncertainties in foreground extinction and the absolute magnitude of the TRGB as well as photometric errors. The distance PPDs obtained for each object both with and without the aforementioned prior are made available to the reader in tabular form. The large object coverage takes advantage of the unprecedented size and photometric depth of the Pan-Andromeda Archaeological Survey. Finally, a preliminary investigation into the satellite density distribution within the halo is made using the obtained distance distributions. For simplicity, this investigation assumes a single power law for the density as a function of radius, with the slope of this power law examined for several subsets of the entire satellite sample. DA - 2012/09/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : be059eb4-4285-40e4-b2e9-0cbb90e3096e ER - TY - JOUR TI - Filamentary star formation: observing the evolution toward flattened envelopes DO - 10.1088/0004-637X/761/2/171 AU - Lee, Katherine AU - Looney, Leslie AU - Johnstone, Doug AU - Tobin, John T2 - The Astrophysical Journal SN - 0004-637X VL - 761 IS - 2 SP - 171 AB - Filamentary structures are ubiquitous from large-scale molecular clouds (a few parsecs) to small-scale circumstellar envelopes around Class 0 sources (∼1000 AU to ∼0.1 pc). In particular, recent observations with the Herschel Space Observatory emphasize the importance of large-scale filaments (a few parsecs) and star formation. The small-scale flattened envelopes around Class 0 sources are reminiscent of the large-scale filaments. We propose an observationally derived scenario for filamentary star formation that describes the evolution of filaments as part of the process for formation of cores and circumstellar envelopes. If such a scenario is correct, small-scale filamentary structures (0.1 pc in length) with higher densities embedded in starless cores should exist, although to date almost all the interferometers have failed to observe such structures. We perform synthetic observations of filaments at the prestellar stage by modeling the known Class 0 flattened envelope in L1157 using both the Combined Array for Research in Millimeter-wave Astronomy (CARMA) and the Atacama Large Millimeter/Submillimeter Array (ALMA). We show that with reasonable estimates for the column density through the flattened envelope, the CARMA D array at 3 mm wavelengths is not able to detect such filamentary structure, so previous studies would not have detected them. However, the substructures may be detected with the CARMA D+E array at 3 mm and the CARMA E array at 1 mm as a result of more appropriate resolution and sensitivity. ALMA is also capable of detecting the substructures and showing the structures in detail compared to the CARMA results with its unprecedented sensitivity. Such detection will confirm the new proposed paradigm of non-spherical star formation. DA - 2012/12/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6379411e-b9c7-4dc8-aabd-d5f47c36b4a2 ER - TY - JOUR TI - The Canada-France-Hawaii telescope legacy survey: stacked images and catalogs DO - 10.1088/0004-6256/143/2/38 AU - Gwyn, Stephen D. J. T2 - The Astronomical Journal SN - 0004-6256 VL - 143 IS - 2 SP - 38 AB - This paper describes the image stacks and catalogs of the Canada-France-Hawaii Telescope Legacy Survey produced using the MegaPipe data pipeline at the Canadian Astronomy Data Centre. The Legacy Survey is divided into two parts. The Deep Survey consists of four fields each of 1 deg^2, with magnitude limits (50% completeness for point sources) of u = 27.5, g = 27.9, r = 27.7, i = 27.4, and z = 26.2. It contains 1.6 × 10^6 sources. The Wide Survey consists of 150 deg^2 split over four fields, with magnitude limits of u = 26.0, g = 26.5, r = 25.9, i = 25.7, and z = 24.6. It contains 3 × 10^7 sources. This paper describes the calibration, image stacking, and catalog generation process. The images and catalogs are available on the web through several interfaces: normal image and text file catalog downloads, a "Google Sky" interface, an image cutout service, and a catalog database query service. © 2012. National Research Council Canada. All rights reserved. DA - 2012/01/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6b5f5b31-81d7-4c2e-bab1-f0c5f8ad703a ER - TY - JOUR TI - The observed properties of dwarf galaxies in and around the Local Group DO - 10.1088/0004-6256/144/1/4 AU - McConnachie, Alan W. T2 - The Astronomical Journal SN - 0004-6256 VL - 144 IS - 1 SP - 4 AB - Positional, structural, and dynamical parameters for all dwarf galaxies in and around the Local Group are presented, and various aspects of our observational understanding of this volume-limited sample are discussed. Over 100 nearby galaxies that have distance estimates reliably placing them within 3Mpc of the Sun are identified. This distance threshold samples dwarfs in a large range of environments, from the satellite systems of the MW and M31, to the quasi-isolated dwarfs in the outer regions of the Local Group, to the numerous isolated galaxies that are found in its surroundings. It extends to, but does not include, the galaxies associated with the next nearest groups, such as Maffei, Sculptor, and IC 342. Our basic knowledge of this important galactic subset and their resolved stellar populations will continue to improve dramatically over the coming years with existing and future observational capabilities, and they will continue to provide the most detailed information available on numerous aspects of dwarf galaxy formation and evolution. Basic observational parameters, such as distances, velocities, magnitudes, mean metallicities, as well as structural and dynamical characteristics, are collated, homogenized (as far as possible), and presented in tables that will be continually updated to provide a convenient and current online resource. As well as discussing the provenance of the tabulated values and possible uncertainties affecting their usage, the membership and spatial extent of the MW sub-group, M31 sub-group, and the Local Group are explored. The morphological diversity of the entire sample and notable sub-groups is discussed, and timescales are derived for the Local Group members in the context of their orbital/interaction histories. The scaling relations and mean stellar metallicity trends defined by the dwarfs are presented, and the origin of a possible "floor" in central surface brightness (and, more speculatively, stellar mean metallicity) at faint magnitudes is considered. © 2012. National Research Council Canada. All rights reserved. DA - 2012/06/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f27c6420-c060-4129-b0cc-8f7812602223 ER - TY - CHAP TI - Alternative proton exchange membranes by chain-growth polymerization DO - 10.1016/B978-0-444-53349-4.00285-5 AU - Tsang, E. M. W. AU - Holdcroft, S. T2 - Polymer Science: A Comprehensive Reference SN - 9780080878621 VL - 10 SP - 651 EP - 689 AB - Polymer microstructure and morphology are critical to the design of proton exchange membranes for fuel cells, as are synthetic methodologies for accessing well-defined polymers with controlled architectures and molecular weights. In this chapter, the synthesis of vinyl-based polymers bearing strong acid groups is considered, together with ion aggregation, phase separation, water sorption, and proton conductivity. Proton-conducting polymers are distinguished according to their microstructure into subheadings of random, block, and graft copolymers. The formation, dimensions, and connectivity of ionic pathways are consistently found to play a profound role in determining both water sorption and proton conductivity. This chapter addresses the significant research that has been carried out to obtain a more comprehensive understanding of relationships between polymer architecture, morphology, and electrolytic properties. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4b418879-0714-4a3b-8207-4931caee044b ER - TY - JOUR TI - Characterization of genes encoding for acquired bacitracin resistance in Clostridium perfringens DO - 10.1371/journal.pone.0044449 AU - Charlebois, Audrey AU - Jalbert, Louis-Alexandre AU - Harel, Josée AU - Masson, Luke AU - Archambault, Marie T2 - PLoS ONE SN - 1932-6203 VL - 7 IS - 9 SP - e44449 KW - ABC transporter KW - bacitracin KW - phosphotransferase KW - thioridazine KW - undecaprenol kinase KW - amino acid sequence KW - antibiotic resistance KW - bacterial strain KW - bacterium isolate KW - bcrABDR gene KW - bcrR gene KW - broiler KW - Clostridium perfringens KW - gene cluster KW - gene identification KW - gene location KW - gene overexpression KW - gene sequence KW - microarray analysis KW - minimum inhibitory concentration KW - morphological trait KW - nucleotide sequence KW - operon KW - pulsed field gel electrophoresis KW - quantitative study KW - regulator gene KW - reverse transcription polymerase chain reaction KW - Clostridium perfringens KW - Drug Resistance, Microbial KW - Electrophoresis, Gel, Pulsed-Field KW - Genes, Bacterial KW - Microbial Sensitivity Tests KW - Molecular Sequence Data KW - Nucleic Acid Hybridization KW - Oligonucleotide Array Sequence Analysis KW - Plasmids KW - Clostridium perfringens KW - Gallus gallus AB - Phenotypic bacitracin resistance has been reported in Clostridium perfringens. However, the genes responsible for the resistance have not yet been characterized. Ninety-nine C. perfringens isolates recovered from broilers and turkeys were tested for phenotypic bacitracin resistance. Bacitracin MIC90 (>256 μg/ml) was identical for both turkey and chicken isolates; whereas MIC50 was higher in turkey isolates (6 μg/ml) than in chicken isolates (3 μg/ml). Twenty-four of the 99 isolates showed high-level bacitracin resistance (MIC breakpoint >256 μg/ml) and the genes encoding for this resistance were characterized in C. perfringens c1261_A strain using primer walking. Sequence analysis and percentages of amino acid identity revealed putative genes encoding for both an ABC transporter and an overproduced undecaprenol kinase in C. perfringens c1261_A strain. These two mechanisms were shown to be both encoded by the putative bcrABD operon under the control of a regulatory gene, bcrR. Efflux pump inhibitor thioridazine was shown to increase significantly the susceptibility of strain c1261_A to bacitracin. Upstream and downstream from the bcr cluster was an IS1216-like element, which may play a role in the dissemination of this resistance determinant. Pulsed-field gel electrophoresis with prior double digestion with I-CeuI/MluI enzymes followed by hybridization analyses revealed that the bacitracin resistance genes bcrABDR were located on the chromosome. Semi-quantitative RT-PCR demonstrated that this gene cluster is expressed under bacitracin stress. Microarray analysis revealed the presence of these genes in all bacitracin resistant strains. This study reports the discovery of genes encoding for a putative ABC transporter and an overproduced undecaprenol kinase associated with high-level bacitracin resistance in C. perfringens isolates from turkeys and broiler chickens. DA - 2012/09/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7283f29b-7cc5-4e44-a55d-654a4de6ff80 ER - TY - JOUR TI - Dry etching of copper phthalocyanine thin films: Effects on morphology and surface stoichiometry DO - 10.3390/molecules170910119 AU - Van Dijken, Jaron G. AU - Brett, Michael J. T2 - Molecules SN - 1420-3049 VL - 17 IS - 9 SP - 10119 EP - 10130 KW - carbon KW - copper KW - indole derivative KW - nitrogen KW - organometallic compound KW - oxygen KW - phthalocyanine copper KW - article KW - chemistry KW - gas laser KW - surface property KW - X ray photoelectron spectroscopy KW - Carbon KW - Copper KW - Indoles KW - Lasers, Gas KW - Nitrogen KW - Organometallic Compounds KW - Oxygen KW - Photoelectron Spectroscopy KW - Surface Properties AB - We investigate the evolution of copper phthalocyanine thin films as they are etched with argon plasma. Significant morphological changes occur as a result of the ion bombardment; a planar surface quickly becomes an array of nanopillars which are less than 20 nm in diameter. The changes in morphology are independent of plasma power, which controls the etch rate only. Analysis by X-ray photoelectron spectroscopy shows that surface concentrations of copper and oxygen increase with etch time, while carbon and nitrogen are depleted. Despite these changes in surface stoichiometry, we observe no effect on the work function. The absorbance and X-ray diffraction spectra show no changes other than the peaks diminishing with etch time. These findings have important implications for organic photovoltaic devices which seek nanopillar thin films of metal phthalocyanine materials as an optimal structure. DA - 2012/08/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 17073649-7a2b-4263-a47f-5fd633a21084 ER - TY - JOUR TI - Specific energy as a characterizing parameter for laser welded Ti-5Al-5V-5Mo-3Cr alloy DO - 10.4028/www.scientific.net/MSF.706-709.2931 AU - Shariff, Tasneem AU - Cao, Xinjin AU - Chromik, Richard AU - Gholipour Baradari, Javad AU - Wanjara, Priti AU - Cuddy, Jonathan AU - Birur, Anand T2 - THERMEC 2011 : International conference on processing and manufacturing of advanced materials : processing, fabrication, properties, applications T2 - Materials Science Forum T3 - 7th International Conference on Processing and Manufacturing of Advanced Materials, THERMEC'2011, August 1-5, 2011, Quebec, QC, Canada SN - 0255-5476 SN - 9783037853030 VL - 706-709 SP - 2931 EP - 2936 KW - Hardness values KW - ND : YAG lasers KW - Specific energy KW - Ti-5553 KW - Welding process KW - Alloys KW - Cerium alloys KW - Chromium alloys KW - Molybdenum KW - Neodymium lasers KW - Titanium KW - Vanadium KW - Welding KW - Titanium alloys KW - Neodymium lasers AB - In this study, specific energy was calculated and correlated with the geometries, defects, microstructures, hardness values and tensile properties of the laser welded Ti-5553 alloy. It was found that specific energy is a good parameter to characterize the laser welding process. DA - 2012/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 540e4d79-089f-4a82-936e-8003263f4f89 ER - TY - JOUR TI - Nanostructured YSZ thin film for application as electrolyte in an electrode supported SOFC DO - 10.4028/www.scientific.net/MSF.727-728.873 AU - Halmenschlager, Cibele Melo AU - KorbRoberto, Maita De Angelis AU - Neagu, Roberto AU - Bergmann, Carlos Pérez AU - Malfatti, Célia de Fraga T2 - Advanced powder technology VIII : selected, peer reviewed papers from the eighth Latin American Conference on Powder Technology, November 6-9, 2011, Florianópolis, Brazil T2 - Materials Science Forum T3 - 8th International Latin-American Conference on Powder Technology, November 6-9, 2011, Florianópolis, Brazi SN - 0255-5476 SN - 9783037854907 VL - 727-728 SP - 873 EP - 878 KW - Dense thin films KW - Different substrates KW - Heat treatment process KW - Nano-structured KW - Oxidization KW - Precursor solutions KW - Pyrolysis process KW - Salt dissolution KW - Solvent influence KW - YSZ thin films KW - Glycerol KW - Scanning electron microscopy KW - Solid oxide fuel cells (SOFC) KW - Spray pyrolysis KW - Thermoanalysis KW - X ray diffraction KW - Yttria stabilized zirconia KW - Yttrium KW - Zirconia KW - Zirconium KW - Vapor deposition AB - The development of solid oxide fuel cell with thin film concepts for an electrode supported design based on the yttria-stabilized zirconia has demonstrated favourable results due to its high chemistry stability in oxidization and environment reduction. The spray pyrolysis process was investigated in order to obtain dense thin films of YSZ on different substrates. The precursor solution was obtained by zirconium and yttrium salt dissolutions in a mixture of water and glycerine in several ratios to study the solvent influence. The substrate was initially heated at 600 °C and during the deposition it ranged from 260-350°C, finishing at a fast increase in temperature of 600°C. The heat treatment was carried out in four different temperatures: 700 °C, 750 °C, 800 °C, and 900 °. The precursors were characterized by thermal analysis. The microstructures of the films were studied using scanning electron microscopy and X-ray diffraction. The results obtained showed that the films obtained were crystalline before the heat treatment process and have shown ionic conductivity above 800°C. DA - 2012/08/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1e40f8ca-fb38-4229-89e5-4af2ee3d8e72 ER - TY - JOUR TI - Study of the interaction of polymethylmethacrylate fragments with methyl isobutyl ketone and isopropyl alcohol DO - 10.1116/1.4766318 AU - Mohammad, Mohammad Ali AU - Poulose Santo, Kolattukudy AU - Dew, Steven K. AU - Stepanova, Maria T2 - Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures SN - 1071-1023 VL - 30 IS - 6 SP - 06FF11 KW - Development process KW - Dissolution behavior KW - Exposure sensitivity KW - Flory-Huggins theory KW - Fragment sizes KW - Gyration radii KW - Interaction mechanisms KW - Isopropyl alcohols KW - Kinetic factors KW - Materials Studio KW - Methyl isobutyl ketone KW - Molecular dynamics simulations KW - Molecular scale KW - Polymer fragments KW - Electron beam lithography KW - Ketones KW - Molecular dynamics KW - Organic compounds KW - Polyesters KW - Polymers KW - Acrylic monomers AB - Exposure of polymethylmethacrylate (PMMA) during electron beam lithography (EBL) produces small polymer fragments that dissolve rapidly during the development process. The resist dissolution behavior varies greatly depending on the nature of the developer (solvent) and therefore influences the selection of the EBL parameters, such as dose (sensitivity). A molecular scale examination of the development process is necessary to elucidate the resist-developer interaction mechanisms. In this work, the authors investigate the interaction of short PMMA chains (containing up to 10 MMA units) with common developer components methyl isobutyl ketone (MIBK) and isopropyl alcohol (IPA). For this purpose, the authors conduct molecular dynamics simulations using the Accelrys Materials Studio package. The simulation results were used to characterize the mixtures in the spirit of the Flory-Huggins theory of polymers and also to extract the diffusivities. The authors found that the behavior of PMMA fragments differed considerably in MIBK as compared with IPA. PMMA fragments containing more than three monomers exhibit stronger attractive interaction with MIBK. For all fragment sizes simulated, the diffusivity of PMMA fragments is 60-160 higher in MIBK as well. Similarly, the authors observed differences in the gyration radii. The authors conclude that the kinetic factor seems to be more significant as compared to affinity factor when accounting for differences in exposure sensitivities due to developer selection. DA - 2012/11/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 28580cff-41ef-44e8-bcbd-69dfa9684891 ER - TY - JOUR TI - Metal oxide morphology in argon-assisted glancing angle deposition DO - 10.1116/1.3687204 AU - Sorge, J. B. AU - Taschuk, M. T. AU - Wakefield, N. G. AU - Sit, J. C. AU - Brett, M. J. T2 - Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films SN - 0734-2101 VL - 30 IS - 2 SP - 21507 KW - Argon flux KW - Beam geometry KW - Birefringent thin films KW - Columnar architectures KW - Deposition process KW - Film density KW - Film materials KW - Glancing Angle Deposition KW - Metal oxides KW - Nanoscale films KW - Thin-film deposition technique KW - Tilt angle KW - Vapor fluxes KW - Metallic compounds KW - Photonic crystals KW - Specific surface area KW - Morphology AB - Glancing angle deposition (GLAD) is a thin film deposition technique capable of fabricating columnar architectures such as posts, helices, and chevrons with control over nanoscale film features. Argon bombardment during deposition modifies the GLAD process, producing films with new morphologies which have shown promise for sensing and photonic devices. The authors report modification of column tilt angle, film density, and specific surface area for 12 different metal oxide and fluoride film materials deposited using Ar-assisted GLAD. For the vapor flux/ion beam geometry and materials studied here, with increasing argon flux, the column tilt increases, film density increases, and specific surface area decreases. With a better understanding of the nature of property modification and the mechanisms responsible, the Ar-assisted deposition process can be more effectively targeted towards specific applications, including birefringent thin films or photonic crystal square spirals. © 2012 American Vacuum Society. DA - 2012/02/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4ee0f305-ea98-493a-af2c-b28a345f33a5 ER - TY - JOUR TI - Nanopillar ITO electrodes via argon plasma etching DO - 10.1116/1.4729592 AU - Van Dijken, Jaron G. AU - Brett, Michael J. T2 - Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films SN - 0734-2101 VL - 30 IS - 4 SP - 40606 KW - Ar plasmas KW - Argon plasma etching KW - Columnar morphology KW - Electrical conductivity KW - Forming gas KW - Indium tin oxide KW - ITO electrodes KW - ITO films KW - Nanopillars KW - Organic solar cell KW - Vertically aligned KW - Electric conductivity KW - Opacity KW - Tin oxides KW - Nanostructures AB - The authors demonstrate the formation of vertically aligned indium tin oxide (ITO) nanopillars by exposing planar ITO films to Ar plasma, the conditions of which determine the size, spacing, and aspect ratio of the pillars. Annealing in air and forming gas is used to recover and optimize the optical transmittance and electrical conductivity of the nanopillar films. The final product is an ITO film whose superior optical transmittance and strong electrical conductivity combine with its robust columnar morphology and processing scalability to make it suitable for use in highly absorbing organic solar cells. DA - 2012/06/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 044355a0-50c8-4472-bf80-c41c68a75713 ER - TY - JOUR TI - FITC delivery into plant cells using magnetic single-walled carbon nanotubes DO - 10.1166/jnn.2012.6449 AU - Hao, Yuzhi AU - Yang, Xiaoyan AU - Shi, Yongzhong AU - Xing, James AU - Marowitch, Janet AU - Chen, Jianmin AU - Chen, Jie T2 - Journal of Nanoscience and Nanotechnology SN - 1533-4880 VL - 12 IS - 8 SP - 6287 EP - 6293 KW - Covalently bonded KW - Endosomes KW - FITC Delivery KW - Fluorescein isothiocyanate KW - Magnetic force KW - Magnetic Single-Walled Carbon Nanotubes (SWCNTs) KW - Nuclear membranes KW - Plant cells KW - Protoplast of Canola and Carrot KW - TEM images KW - Cell membranes KW - Plant cell culture KW - Single-walled carbon nanotubes (SWCN) AB - In this paper, fluoresce in isothiocyanate (FITC) was covalently bonded with magnetic single-walled carbon nanotubes (mSWCNTs) that were purified using our previous method. To demonstrate our design, mSWCNT-FITC was delivered into plant cells (canola and carrot cells) driven by external magnetic forces. From FACS results, the FITC delivery efficiency was about 100% for both two canola and carrot protoplasts, which were further confirmed by the confocal and sectional TEM images. Some mSWCNTs were found trapped both inside the endosomes of canola protoplast and outside endosome near the nuclear membrane of carrot protoplast according to the sectional TEM images. All results showed that mSWCNT is a good delivery carrier for biomolecules. DA - 2012/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2fc29e6c-1675-4e3c-8ad5-9751c6419f2d ER - TY - JOUR TI - Magnetic gold nanoparticles: synthesis, characterization and its application in the delivery of FITC into KG-1 cells DO - 10.1166/jnn.2012.6647 AU - Hao, Yuzhi AU - Song, Steven AU - Yang, Xiaoyan AU - Xing, James AU - Chen, Jie T2 - Journal of Nanoscience and Nanotechnology SN - 1533-4880 VL - 12 IS - 10 SP - 7716 EP - 7722 KW - Confocal imaging KW - Core shell structure KW - Iron oxide nanoparticle KW - Isothiocyanates KW - Magnetic force KW - Magnetic nanoparticles KW - Micropores KW - Solution treatments KW - Sonication method KW - Spherical morphologies KW - Flow cytometry KW - Metal nanoparticles KW - Organic acids KW - Synthesis (chemical) KW - fluorescein isothiocyanate KW - atomic force microscopy KW - confocal microscopy KW - fluorescence microscopy AB - In this article, we report a new method\-a sonication method to disperse iron oxide nanoparticles into smaller nanoparticles and make gold ions absorb onto the surface or trapped in the micropores of the iron oxide nanoparticles using sonication action. By using quick reduction of ascorbic acid and post-HCl solution treatment, gold covered magnetic nanoparticles (mGNPs) with spherical morphology and uniform size were synthesized in a water solution. The size of the mGNPs was found to be 20-30 nm. Some ideal mGNPs possessed a core-shell structure. The mGNPs were non-cytotoxic and mGNP-fluorescein isothiocyanate (FITC) can enter KG-1 cells when driven by an external magnetic force, which was confirmed by confocal imaging. The confocal image also showed the FITC inside the KG-1 cells was near the nucleus. The fluorescein isothiocyanate (FITC) delivery efficiency is about 100% according to the flow cytometry results. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 11c53ebf-4b5b-4e08-a29e-a9652970c616 ER - TY - JOUR TI - Silicon nanowire core aluminum shell coaxial nanocomposites for lithium ion battery anodes grown with and without a TiN interlayer DO - 10.1039/c2jm16167b AU - Memarzadeh, Elmira L. AU - Kalisvaart, W. Peter AU - Kohandehghan, Alireza AU - Zahiri, Beniamin AU - Holt, Chris M. B. AU - Mitlin, David T2 - Journal of Materials Chemistry SN - 0959-9428 VL - 22 IS - 14 SP - 6655 EP - 6668 KW - Al coatings KW - Barrier layers KW - Capacity loss KW - Capacity retention KW - Coulombic efficiency KW - Current collector KW - Cycling performance KW - Electrical contacts KW - Electrochemical performance KW - First cycle KW - First discharge KW - Growth substrates KW - Impedance spectroscopy KW - Irreversible capacity loss KW - Lithiation KW - Lithium-ion battery KW - Morphology changes KW - SEM analysis KW - Silicon nanowires KW - Solid electrolyte interfaces KW - Specific capacities KW - Alumina KW - Atomic layer deposition KW - Electrochemical electrodes KW - Lithium batteries KW - Lithium compounds KW - Nanocomposites KW - Solid electrolytes KW - Tinning KW - Titanium nitride AB - We investigated the effect of aluminum coating layers and of the support growth substrates on the electrochemical performance of silicon nanowires (SiNWs) used as negative electrodes in lithium ion battery half-cells. Extensive TEM and SEM analysis was utilized to detail the cycling induced morphology changes in both the Al-SiNW nanocomposites and in the baseline SiNWs. We observed an improved cycling performance in the Si nanowires that were coated with 3 and 8 wt.% aluminum. After 50 cycles, both the bare and the 3 wt.% Al coated nanowires retained 2600 mAh/g capacity. However beyond 50 cycles, the coated nanowires showed higher capacity as well as better capacity retention with respect to the first cycle. Our hypothesis is that the nanoscale yet continuous electrochemically active aluminum shell places the Si nanowires in compression, reducing the magnitude of their cracking/disintegration and the subsequent loss of electrical contact with the electrode. We combined impedance spectroscopy with microscopy analysis to demonstrate how the Al coating affects the solid electrolyte interface (SEI). A similar thickness alumina (Al 2O 3) coating, grown via atomic layer deposition (ALD), was shown not to be as effective in reducing the long-term capacity loss. We demonstrate that an electrically conducting TiN barrier layer present between the nanowires and the underlying stainless steel current collector leads to a higher specific capacity during cycling and a significantly improved coulombic efficiency. Using TiN the irreversible capacity loss was only 6.9% from the initial 3581 mAh/g, while the first discharge (lithiation) capacity loss was only 4%. This is one of the best combinations reported in literature. DA - 2012/02/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 07b5a687-ba83-419d-924b-bc80ffd786ca ER - TY - JOUR TI - Microelectronic-sensing assay to detect presence of Verotoxins in human faecal samples DO - 10.1111/j.1365-2672.2012.05321.x AU - Xing, J. Z. AU - Zhu, L. AU - Huang, B. AU - Chen, J. AU - Gabos, S. T2 - Journal of Applied Microbiology SN - 1364-5072 VL - 113 IS - 2 SP - 429 EP - 437 KW - Escherichia coli; real-time cell electronic sensing assay; vero cell assay; verotoxin assay AB - Aims: To develop a novel Vero cell assay that implements a real-time cell electronic sensing (RT-CES) system for the determination of the presence of verotoxin-producing Escherichia coli (VTEC). The assay overcomes the major drawbacks in conventional Vero cell assay, for example, labour-intensive and time-consuming. Methods and Results: Cells were grown onto the surfaces of microelectronic sensors that are integrated into the bottom surfaces of the microtiter plate. Cellular viability was monitored in real-time and quantified based on changes in the sensor's electrical impedance. For cell viability measurement, the data generated on the RT-CES system correlated well with those obtained by the Vero cell assay for Verotoxins. To assess cytotoxicity, test cells growing on microelectronic sensors were treated with either supernatant from pure cultures, or stool samples. The specific neutralizing antibodies of VT1 and VT2 were used to identify specific toxins in the samples. Conclusions: The RT-CES assay provides a sensitive measurement comparable to conventional crystal violet assay. The assay has been successfully and specifically used to identify VTEC in human faecal samples. Significance and Impact of the Study: The RT-CES assay significantly shortens the testing time from 48 to 72h required by the crystal violet assay to only 15h with automated operation. DA - 2012/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d5c0741a-0f7f-4d01-8935-2f5dd4920a29 ER - TY - JOUR TI - Study of development processes for ZEP-520 as a high-resolution positive and negative tone electron beam lithography resist DO - 10.1143/JJAP.51.06FC05 AU - Mohammad, Mohammad Ali AU - Koshelev, Kirill AU - Fito, Taras AU - Zheng, David Ai Zhi AU - Stepanova, Maria AU - Dew, Steven T2 - Japanese Journal of Applied Physics SN - 0021-4922 VL - 51 IS - 2 SP - 06FC05 KW - Analytical method KW - Dense gratings KW - Development process KW - Electron beam resist KW - High resolution KW - High sensitivity KW - Isopropyl alcohols KW - Kinetic models KW - Methyl isobutyl ketone KW - Microscopic parameter KW - Negative tones KW - Performance metrics KW - Positive tone KW - Electron beams KW - Ketones KW - Dissolution AB - ZEP brand electron beam resists are well-known for their high sensitivity and etch durability. The various performance metrics such as sensitivity, contrast, and resolution of ZEP resist depend strongly on the development process. In this work, we investigate the development of ZEP-520 resist through contrast curves, dense gratings, and surface roughness measurements using three different classes of developer systems of varying solvation strength, ZED-N50, methyl isobutyl ketone (MIBK): isopropyl alcohol (IPA) 1:3, and IPA: H 2O 7:3, at the ambient temperature (22 °C) and cold (°15 °C) development conditions. In order to provide a deeper insight into the ZEP development process, we propose a novel kinetic model of dissolution for ZEP, and develop an efficient analytical method that allows determining the microscopic parameters of ZEP dissolution based on experimental contrast curves. We also observe experimentally and characterize the negative tone behavior of ZEP for dense grating patterning and compare its performance with positive tone behavior. DA - 2012/06/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 44c7c328-0848-4e2b-b923-12f8441cfc99 ER - TY - JOUR TI - Linking the chemistry and physics of electronic charge transfer in insulators: theory and experiment AU - Veregin, Richard P. N. AU - Hawkins, Michael S. AU - Li, Qingbin AU - Gusarov, Sergey AU - Kovalenko, Andriy T2 - NIP28 : 28th international conference on digital printing technologies : technical program and proceedings : Digital fabrication 2012 T3 - 28th International Conference on Digital Printing Technologies, NIP 2012 and Digital Fabrication 2012, September 9-13, 2012, Quebec, QC, Canada SN - 9780892083022 SP - 360 EP - 363 KW - Electronic charges KW - Electrophotography KW - Highest occupied molecular orbital KW - Inverse gas chromatography KW - Lowest unoccupied molecular orbital KW - Precursor complexes KW - Quantum-mechanical modeling KW - Triboelectric charging KW - Alumina KW - Chemical potential KW - Density functional theory KW - Gas chromatography KW - Molecular orbitals KW - Photography KW - Quantum theory KW - Silica KW - Surface chemistry KW - Surface states KW - Charge transfer AB - The surface states model is successful in predicting many salient features of charge transfer in insulative materials, which is critical to electrophotography. This paper will discuss how the surface chemistry controls the physics, the chemical potentials, and how it fits the surface states model. The interrelationship of acid-base Ka/Kb values of the materials in contact, measured by IGC (inverse gas chromatography), the HOMO (highest occupied molecular orbitals) and LUMO (lowest unoccupied molecular orbitals) and their excited states calculated using DFT (density functional theory) quantum mechanical modeling, the chemical potentials measured by the Kelvin method, and triboelectric charging data are studied. It will be shown that a precursor complex of the contacting materials, prior to the charge transfer event, can be calculated by DFT to predict both qualitatively and quantitatively triboelectric charging. The work focuses on PTFE, Kynar and PMMA polymers, as well as silica, titania and alumina. DA - 2012/12/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b7e5fe34-a2a8-4473-917d-13f39f04b35f ER - TY - JOUR TI - Multi-platform characterization of the human cerebrospinal fluid metabolome: a comprehensive and quantitative update DO - 10.1186/gm337 AU - Mandal, Rupasri AU - Guo, An Chi AU - Chaudhary, Kruti K. AU - Liu, Philip AU - Yallou, Faizath S. AU - Dong, Edison AU - Aziat, Farid AU - Wishart, David S. T2 - Genome Medicine SN - 1756-994X VL - 4 IS - 4 SP - 38 KW - acylcarnitine KW - amino acid KW - hexose KW - lyso phosphatidylcholine derivative KW - phosphatidylcholine KW - sphingolipid KW - unclassified drug KW - article KW - cerebrospinal fluid KW - direct flow injection mass spectrometry KW - human KW - liquid chromatography KW - mass fragmentography KW - mass spectrometry KW - metabolite KW - metabolome KW - nuclear magnetic resonance KW - priority journal AB - Background: Human cerebral spinal fluid (CSF) is known to be a rich source of small molecule biomarkers for neurological and neurodegenerative diseases. In 2007, we conducted a comprehensive metabolomic study and performed a detailed literature review on metabolites that could be detected (via metabolomics or other techniques) in CSF. A total of 308 detectable metabolites were identified, of which only 23% were shown to be routinely identifiable or quantifiable with the metabolomics technologies available at that time. The continuing advancement in analytical technologies along with the growing interest in CSF metabolomics has led us to re-visit the human CSF metabolome and to re-assess both its size and the level of coverage than can be achieved with today's technologies.Methods: We used five analytical platforms, including nuclear magnetic resonance (NMR), gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), direct flow injection-mass spectrometry (DFI-MS/MS) and inductively coupled plasmas-mass spectrometry (ICP-MS) to perform quantitative metabolomics on multiple human CSF samples. This experimental work was complemented with an extensive literature review to acquire additional information on reported CSF compounds, their concentrations and their disease associations.Results: NMR, GC-MS and LC-MS methods allowed the identification and quantification of 70 CSF metabolites (as previously reported). DFI-MS/MS allowed the quantification of 78 metabolites (6 acylcarnitines, 13 amino acids, hexose, 42 phosphatidylcholines, 2 lyso-phosphatidylcholines and 14 sphingolipids), while ICP-MS provided quantitative results for 33 metal ions in CSF. Literature analysis led to the identification of 57 more metabolites. In total, 476 compounds have now been confirmed to exist in human CSF.Conclusions: The use of improved metabolomic and other analytical techniques has led to a 54% increase in the known size of the human CSF metabolome over the past 5 years. Commonly available metabolomic methods, when combined, can now routinely identify and quantify 36% of the 'detectable' human CSF metabolome. Our experimental works measured 78 new metabolites that, as per our knowledge, have not been reported to be present in human CSF. An updated CSF metabolome database containing the complete set of 476 human CSF compounds, their concentrations, related literature references and links to their known disease associations is freely available at the CSF metabolome database. DA - 2012/04/30 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : de9e3e4d-dbb6-41ec-96d4-1288a8d04070 ER - TY - JOUR TI - Mode suppressing packaging for 50 GHz cryogenic low-noise amplifiers AU - Henke, Doug AU - Jiang, Frank AU - Claude, Stéphane T2 - Microwave Conference (EuMC), 2012 42nd European T3 - 2012 42nd European Microwave Conference, EuMC 2012 - Held as Part of 15th European Microwave Week, EuMW 2012, October 29 - November 1, 2012, Amsterdam, Netherlands SN - 978-2-87487-026-2 SN - 978-1-4673-2215-7 SN - 978-2-87487-027-9 SP - 6459085 SP - 1003 EP - 1006 KW - Higher-order modes KW - Open Access KW - Photonic band-gap structures KW - Photonic bandgap (PBG) KW - Cryogenics KW - Microwave amplifiers KW - Microwaves KW - Millimeter wave devices KW - Packaging KW - Periodic structures KW - Spontaneous emission KW - Low noise amplifiers AB - Hybrid cryogenic low-noise amplifiers are often enclosed in a metallic housing with several bias channels. Strict machining tolerance is necessary for solid clamping of the lid to avoid degradation in performance. A new packaging is proposed by applying photonic bandgap (PBG) structures; which greatly relaxes the tolerance on clamping' results in natural bias channels' suppresses higher order modes' and creates wide open access for assembly. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e3182650-e073-4c12-852f-1dbcd8b2ce37 ER - TY - JOUR TI - Ultrafast carrier dynamics in silicon nanocrystal films DO - 10.1149/1.3700406 AU - Titova, Lyubov V. AU - Cocker, Tyler L. AU - Wang, Xiongyao AU - Meldrum, Al AU - Hegmann, Frank A. T2 - Nanoscale Luminescent Materials 2 T2 - ECS Transactions; 45 T3 - 2nd International Symposium on Nanoscale Luminescent Materials - 221st ECS Meeting, May 6-10, 2012, Seattle, WA, USA SN - 1938-5862 SN - 9781566779579 SP - 21 EP - 29 KW - Carrier localization KW - Drude models KW - Filling fractions KW - Interface defects KW - Interface scattering KW - Nanocrystal sizes KW - Optical emissions KW - Percolation thresholds KW - Photoexcited carriers KW - Picosecond time scale KW - Si nanocrystal KW - Silicon nanocrystals KW - Thz spectroscopy KW - Time variations KW - Time-resolved KW - Time-scales KW - Ultrafast carrier dynamics KW - Nanocrystals KW - Nanotechnology KW - Optical waveguides KW - Percolation (computer storage) KW - Percolation (fluids) KW - Photoexcitation KW - Silicon KW - Interfaces (materials) AB - We have applied time-resolved THz spectroscopy to probe the transient photoexcited carrier dynamics and THz conductivity in Si nanocrystal films with varying silicon volume filling fractions and nanocrystal sizes on picosecond time scales. The THz conductivity reveals microscopic carrier motion with significant interface scattering within nanocrystals as well as percolative transport between nanocrystals. The time variation of the THz conductivity is analyzed within the framework of the Drude-Smith model, an extension of the Drude model that characterizes carrier localization in nanostructured materials. Below the percolation threshold, transport between nanocrystals is inhibited and photoexcited carriers are localized within individual nanocrystals. These films also exhibit efficient optical emission. In films with Si filling fractions above the percolation threshold, photoluminescence is suppressed and a transition from long-range inter-nanocrystal transport immediately after photoexcitation to increased carrier localization over a 50 ps time scale due to accumulation of charges at interface defect sites is observed. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1af14a35-2335-46d8-b840-ba89897c326b ER - TY - JOUR TI - Molecular theory of solvation and electrical double layer in nanoporous carbon electrodes DO - 10.1149/1.3693069 AU - Kovalenko, Andriy T2 - Electrochemical capacitors, fundamentals to applications T2 - ECS Transactions; 41 T3 - Electrochemical Capacitors: Fundamentals to Applications - 220th ECS Meeting, October 9-14, 2011, Boston, MA, USA SN - 1938-5862 SN - 9781566779623 SN - 9781607683216 SP - 133 EP - 149 KW - Electrical double layers KW - Electrochemical capacitor KW - Electrochemical supercapacitor KW - Electrolyte solutions KW - Molecular theory of solvation KW - Nano-porous materials KW - Nanoporous carbon electrode KW - Quenched-annealed systems KW - Capacitors KW - Electric properties KW - Electrochemical electrodes KW - Morphology KW - Nanopores KW - Plasma interactions KW - Porous materials KW - Solvation KW - Statistical mechanics KW - Thermodynamics KW - Electrolytes AB - Electrical double layer (EDL) in a nanoporous electrode is very different from a planar electrochemical capacitor. The statistical-mechanical, molecular theory of solvation structure and thermodynamics (a.k.a. RISM-KH) is an essential part of multiscale methodology properly accounting for environment effects and chemical specificities of nanosystems in solution. Its generalization to solutions sorbed in disordered nanoporous materials using the replica method for statistical mechanics of quenched-annealed systems, replica RISM-KH-VM theory, provides full microscopic details of the solvation structure and thermodynamics as well as the electrochemical properties averaged over the thermal motion of sorbed solution and over quenched morphology of host nanoporous material. The replica RISM-KH-VM theory reveals the molecular mechanisms and driving forces of sorption of electrolyte solution in a nanoporous carbon electrode which are drastically different from the electrical double layer in electrolyte solution at a planar electrode. These include nanoporous confinement morphology and external charge, size and chemical specificities of solvent and electrolyte, osmotic forces, the internal EDL at the surface of nanopores and the external EDL at the contact with bulk solution. The interplay of these factors determines the efficiency of an electrosorption cell and the specific capacitance of the electrochemical supercapacitor. DA - 2012 PY - 2012 PB - Electrochemical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5889eafc-850e-441b-8b67-e6096418b7e9 ER - TY - JOUR TI - Real-time monitoring of adherent Vero cell density and apoptosis in bioreactor processes DO - 10.1007/s10616-011-9421-2 AU - Petiot, Emma AU - El-Wajgali, Amal AU - Esteban, Geoffrey AU - Gény, Cécile AU - Pinton, Hervé AU - Marc, Annie T2 - Cytotechnology SN - 0920-9069 VL - 64 IS - 4 SP - 429 EP - 441 KW - apoptosis KW - in situ monitoring KW - cell density KW - Multi-frequency permittivity KW - Adherent Vero cell AB - This study proposes an easy to use in situ device, based on multi-frequency permittivity measurements, tomonitor the growth and death ofattached Vero cells cultivated on microporous microcarriers, without any cell sampling. Vero cell densities were on-line quantified up to 10 6 cell mL -1. Some parameters which could potentially impact Vero cell morphological and physiological states were assessed through different culture operating conditions, such as media formulation or medium feed-harvest during cell growth phase. A new methodofinsitu cell death detection with dielectric spectroscopy was also successfully implemented. Thus, through permittivity frequency scanning, major rises of the apoptotic cell population in bioreactor cultures were detected by monitoring the characteristic frequency of the cell population, f c, which is one of the culture dielectric parameters. Both cell density quantification and cell apoptosis detection are strategic information in cell-based production processes as they are involved in major events of the process, suchasscale-uporchoice of the viral infection conditions. This new application of dielectric spectroscopy to adherent cell culture processes makes it a very promising tool for risk-mitigation strategy in industrial processes. Therefore, our results contribute to the development of Process Analytical Technology in cell-based industrial processes. DA - 2012/08/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ab722eba-398b-44e3-8fe4-926f1fbabe0c ER - TY - JOUR TI - Efficient and rapid uptake of magnetic carbon nanotubes into human monocytic cells: implications for cell-based cancer gene therapy DO - 10.1007/s10529-012-0858-y AU - Gul-Uludag, Hilal AU - Lu, Weibing AU - Xu, Peng AU - Xing, James AU - Chen, Jie T2 - Biotechnology Letters SN - 0141-5492 VL - 34 IS - 5 SP - 989 EP - 993 KW - Cancer KW - Cellular and nuclear uptake KW - Fluorescein isothiocyanate KW - Gene therapies KW - Magnetic carbon nanotubes KW - Monocytic leukemia cells AB - Monocyte-based gene therapies in cancer have been hampered by either the resistance of these cells to non-viral molecular delivery methods or their poor trafficking to the tumor site after their ex vivo manipulations. Magnetic nanoparticles (MNP)-loaded genetically engineered monocytes can efficiently delivered to tumor site by external magnetic field, but they are not ideal delivery tools due to their spherical shape. Hence, we have investigated the cellular uptake efficiency and cytotoxicity of fluorescein isothiocyanate (FITC)-labelled magnetic carbon nanotubes (FITC-mCNT) in human monocytic leukemia cell line THP-1 for application in cell-based gene therapy against cancer. Uptake of FITC-mCNT into THP-1 cells reached 100% only 1 h after the delivery. Confocal imaging confirmed that FITC-mCNT entered the cell cytoplasm and even into the nucleus. FITC-mCNT uptake did not compromise cell viability. This delivery system might therefore enhance cell-based cancer gene therapies. DA - 2012/05/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2265506a-9011-4482-89f5-83a5e75598be ER - TY - JOUR TI - Evolution in the volumetric type Ia supernova rate from the supernova legacy survey DO - 10.1088/0004-6256/144/2/59 AU - Perrett, K. AU - Sullivan, M. AU - Conley, A. AU - González-Gaitán, S. AU - Carlberg, R. AU - Fouchez, D. AU - Ripoche, P. AU - Neill, J. D. AU - Astier, P. AU - Balam, D. AU - Balland, C. AU - Basa, S. AU - Guy, J. AU - Hardin, D. AU - Hook, I. M. AU - Howell, D. A. AU - Pain, R. AU - Palanque-Delabrouille, N. AU - Pritchet, C. AU - Regnault, N. AU - Rich, J. AU - Ruhlmann-Kleider, V. AU - Baumont, S. AU - Lidman, C. AU - Perlmutter, S. AU - Walker, E. S. T2 - Astronomical Journal SN - 0004-6256 VL - 144 IS - 2 SP - 59 AB - We present a measurement of the volumetric Type Ia supernova (SN Ia) rate (SNR Ia) as a function of redshift for the first four years of data from the Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS). This analysis includes 286 spectroscopically confirmed and more than 400 additional photometrically identified SNe Ia within the redshift range 0.1 ≤ z ≤ 1.1. The volumetric SNR Ia evolution is consistent with a rise to z 1.0 that follows a power law of the form (1+z) α, with α = 2.11 ± 0.28. This evolutionary trend in the SNLS rates is slightly shallower than that of the cosmic star formation history (SFH) over the same redshift range. We combine the SNLS rate measurements with those from other surveys that complement the SNLS redshift range, and fit various simple SN Ia delay-time distribution (DTD) models to the combined data. A simple power-law model for the DTD (i.e., t -β) yields values from β = 0.98 ± 0.05 to β = 1.15 ± 0.08 depending on the parameterization of the cosmic SFH. A two-component model, where SNR Ia is dependent on stellar mass (M stellar) and star formation rate (SFR) as SNR Ia(z) = A × M stellar(z) + B × SFR(z), yields the coefficients A = (1.9 ± 0.1) × 10 -14 SNe yr -1 M -1 ⊙ and B = (3.3 ± 0.2) × 10 -4 SNe yr -1 (M ⊙ yr -1) -1. More general two-component models also fit the data well, but single Gaussian or exponential DTDs provide significantly poorer matches. Finally, we split the SNLS sample into two populations by the light-curve width (stretch), and show that the general behavior in the rates of faster-declining SNe Ia (0.8 ≤ s < 1.0) is similar, within our measurement errors, to that of the slower objects (1.0 ≤ s < 1.3) out to z 0.8. © © 2012. The American Astronomical Society. All rights reserved.. DA - 2012/07/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1daec57e-16dc-4d90-8a36-7846d310ae98 ER - TY - JOUR TI - Sky coverage modeling for the whole sky for laser guide star multiconjugate adaptive optics DO - 10.1364/AO.51.003692 AU - Wang, Lianqi AU - Andersen, David AU - Ellerbroek, Brent T2 - Applied Optics SN - 0003-6935 VL - 51 IS - 16 SP - 3692 EP - 3700 KW - Laser guide star adaptive optics KW - Multi-conjugate adaptive optics systems KW - Natural guide star KW - Sky coverage KW - Thirty Meter Telescope KW - Wave front sensors KW - Wavefronts AB - The scientific productivity of laser guide star adaptive optics systems strongly depends on the sky coverage, which describes the probability of finding natural guide stars for the tip/tilt wavefront sensor(s) to achieve a certain performance. Knowledge of the sky coverage is also important for astronomers planning their observations. In this paper, we present an efficient method to compute the sky coverage for the laser guide star multiconjugate adaptive optics system, the Narrow Field Infrared Adaptive Optics System (NFIRAOS), being designed for the Thirty Meter Telescope project.We show that NFIRAOS can achieve more than 70% sky coverage over most of the accessible sky with the requirement of 191 nm total rms wavefront. DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a4a0eab0-53c8-4792-8997-b11dbe3f5820 ER - TY - JOUR TI - Naturally aspirating isokinetic total water content probe: pre-flight wind tunnel testing and design modifications DO - 10.2514/6.2012-3040 AU - Davison, Craig R. AU - Rutke, Tim AU - Strapp, J. Walter AU - Ratvasky, Thomas P. AU - Emery, Edward F. T2 - 4th AIAA Atmospheric and Space Environments Conference T3 - 4th AIAA Atmospheric and Space Environments Conference 2012, June 25-28, 2012, New Orleans, LA, USA SN - 9781624101922 DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5b2c5ac4-cad9-41d1-9f6e-889c7a895edb ER - TY - JOUR TI - Photonic crystal paddle nanocavities for optomechanical torsion sensing DO - 10.1364/CLEO_SI.2012.CW1M.7 AU - Wu, Marcelo AU - Hryciw, Aaron C. AU - Khanaliloo, Behzad AU - Freeman, Mark R. AU - Davis, John P. AU - Barclay, Paul E. T2 - 2012 Conference on Lasers and Electro-Optics (CLEO) T3 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012, May 6-11, 2012, San Jose, CA, USA SN - 9781467318396 SN - 978-1-55752-943-5 KW - Crystal nanocavities KW - Low mass KW - Nano-cavities KW - Optomechanical KW - Torsional forces KW - Lasers KW - Photonic crystals AB - Photonic crystal nanocavities with suspended central elements suitable for optomechanical detection of torsional forces are designed and fabricated. This "floating" low mass nanocavity may be mechanically coupled to nanomagnetic structures. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5fbe6ebe-95be-4832-b34a-c1fc2f421f97 ER - TY - JOUR TI - Effective g-factor in high-mobility InGaAs/InP quantum well DO - 10.7498/aps.61.127102 AU - Wei, Lai-Ming AU - Zhou, Yuan-Ming AU - Yu, Guo-Lin AU - Gao, Kuang-Hong AU - Liu, Xin-Zhi AU - Lin, Tie AU - Guo, Shao-Ling AU - Dai, Ning AU - Chu, Jun-Hao AU - Austing, David Guy T2 - Acta Physica Sinica SN - 1000-3290 VL - 61 IS - 12 SP - 127102 AB - High-mobility In 0.53Ga 0.47As/InP quantum well is fabricated by the chemical beam epitaxy technique. Clear Shubnikov-de Hass (SdH) oscillation and beating pattern due to zero-field spin splitting are observed by magnetotransport measurements at low temperature. We use an analytical method, involving the simultaneous fitting of fast Fourier transform spectra of SdH oscillations at different tilted fields, to extract the effective g-factor. DA - 2012/06/20 PY - 2012 LA - zho C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6f547d4e-6aa9-497b-8d27-acefc084f379 ER - TY - JOUR TI - A rapid fuzzy optimisation approach to multiple sources water blending problem in water distribution systems DO - 10.1080/1573062X.2011.652133 AU - Peng, Wei AU - Mayorga, Rene V. AU - Imran, Syed T2 - Urban Water Journal SN - 1573-062X VL - 9 IS - 3 SP - 177 EP - 187 KW - water quality, water blend, multi-objective, fuzzy linear programming, response surface method AB - This paper proposes a Fuzzy Response Surface Optimisation (FRSO) approach for the water blending problem of multiple sources to maintain the water quality in water distribution systems. In the proposed approach, instead of the more precise and complicated nonlinear equations, the response surface models are used to describe the harmful reaction kinetics. The objectives of this study are to minimise the harmful reactions in the water network. A fuzzy linear programming using the min-operator approach is applied to handle the multiple objectives. Due to the FRSO only containing quadratic models, this approach is easy to apply and the optimisation is performed rapidly. Hence, the FRSO can be used to dynamically estimate the optimal blending ratios of water coming from multiple sources. Finally, a case study and two comparisons demonstrate the FRSO's advantages as to computational efficiency and simultaneous optimisation. DA - 2012/04/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 72e5f231-f03b-46e8-809c-f310a72334c1 ER - TY - JOUR TI - The effect of overlap percentage on surface quality in laser polishing of AISI H13 tool steel AU - Hafiz, Abdullah Khalid AU - Bordatchev, Evgueni AU - Tutunea-Fatan, Remus T2 - 40th North American Manufacturing Research Conference 2012: Notre Dame, Indiana, USA, 4-8 June 2012. T2 - Transactions of the North American Manufacturing Research Institution of SME T3 - 40th Annual North American Manufacturing Research Conference, NAMRC40, June 4-8, 2012, Notre Dame, IN, USA SN - 1047-3025 SN - 9781622762477 VL - 40 SP - 351 EP - 360 KW - AISI H13 KW - Energy density KW - Laser polishing KW - Overlap percentage KW - Surface waviness KW - Industrial research KW - Lasers KW - Manufacture KW - Polishing KW - Surface roughness KW - Tool steel KW - Transfer functions KW - Surface properties AB - Polishing by laser beam radiation is a novel technique used to modify the initial surface geometry in order to achieve a desired level of surface finish. The performance of laser polishing (LP) is determined by its process parameters, whose optimum combination is essential for the achievement of the best possible surface quality. In this regard, the overlap percentage is one of the important LP settings, which indicates the level of the overlap between two consecutive polishing tracks. In the current study, the effects of overlap percentage were experimentally investigated in the context of AISI H13 tool steel LP operations. Four surface areas were polished using four different overlap percentages but the same applied energy density. The improvement of surface quality was measured by average spatial surface roughness and material ratio function. The surface quality improvement was also analyzed by means of statistical analysis using the autospectrum and the transfer functions. Finally, the polished area created by the optimum overlap from the aforementioned analyses was further processed by an additional level of LP improving a total average surface roughness from 1.59 μm to 0.18 μm (89% improvement). DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8e6fb0ab-42f5-4be4-afe5-8d67db40781d ER - TY - JOUR TI - The roles of diffusion factors in electrochemical corrosion of TiN and CrN (CrSiCN) coated mild steel and stainless steel AU - Cai, Feng AU - Yang, Qi AU - Huang, Xiao T2 - TMS 2012, 141st Annual Meeting & Exhibition, Supplemental Proceedings. Volume 1, Materials Processing and Interfaces T3 - TMS 2012: 141st Annual Meeting and Exhibition, March 11-15, 2012, Orlando, FL, USA SN - 9781118296073 SN - 1118296079 SP - 49 EP - 56 KW - PVD coating, coating defect, corrosion, electrochemical impedance, EIS AB - Applying noble coatings on steel components is an effective solution to preventing corrosion attacks. However, through-coating defects, such as pin holes, voids and growth defects play a detrimental role in the degradation of a coating-substrate system. Through the defects, corrosive media are able to reach the metal substrate, initializing pitting corrosion and eventually resulting in coating failure. This research studies the correlation between coating defects and corrosion behavior of the TiN and CrN (CrSiCN) coated mild steel and stainless steel. Electrochemical impedance technique is used to reveal the corrosion behavior. The results revealed that in a coating-substrate system, two critical factors controlling the corrosion resistance, the effective diffusion coefficient and diffusion layer thickness, which are found to be related to coating microstructure. Denser and thicker coating structures result in lower effective diffusion coefficients and greater effective diffusion layer thickness, and demonstrate high electrochemical impedance and resistance to electrochemical corrosion. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c78a985d-14c3-4652-a634-72413f07173e ER - TY - JOUR TI - Toxicological effects of functionalized single-walled carbon nanotubes (SWCNTs) on embryonic zebrafish (Danio rerio) AU - Felix, L. AU - Martinez-Rubi, Y. AU - Simard, B. AU - Goss, G. T2 - Nanotechnology 2012: Technical Proceedings of the 2012 NSTI Nanotechnology Conference and Expo. Volume 3: Bio Sensors, Instruments, Medical, Environment and Energy T3 - Nanotech Conference and Expo 2012, June 18-21, 2012, Santa Clara, CA, USA SN - 9781466562769 SP - 327 EP - 330 KW - Aquatic animals KW - Aquatic ecosystem KW - Chemical functionalization KW - Nanotoxicology KW - Potential indicators KW - Pristine materials KW - Sublethal effects KW - Toxicological effects KW - Medical nanotechnology AB - Since their discovery in 1993, single-walled carbon nanotubes (SWCNTs) have played an integral role in nanotechnology and have been extensively studied due to their unique structural, electrical and mechanical properties. Chemical functionalization and coating of SWCNTs can improve their solubility in water and organic solvents to allow use in solution-based techniques and extend range of applications. We tested 1) aqueous lignin-wrapped 10-20nm and 2) carboxy-functionalized 10-20 nm SWCNTs, manufactured by the National Research Council - Steacie Institute for Molecular Sciences (NRC-SIMS), to determine the effect of different degrees of solubility. To determine the toxicological effect, we exposed zebrafish (Danio rerio) embryos over a 72-hour period to a range (1, 10, 50, 100 and 200mg/L) of functionalized and un-functionalized SWCNTs as a paired control following Organization for Economic Co-Operation and Development (OECD) guidelines. Toxicological endpoints such as lethality, hatch inhibition and changes in gene expression were measured. While preliminary results show no significant difference in survival and hatch compared to control, effects may occur at the molecular level. Our goal was to determine the toxicological effects of different degrees of functionalized SWCNTs at whole animal and molecular levels. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 28cac52d-d29d-4d0f-97a9-048e9aefb0af ER - TY - JOUR TI - Applications of amniotic membrane and fluid in stem cell biology and regenerative medicine DO - 10.1155/2012/721538 AU - Rennie, Kerry AU - Gruslin, Andrée AU - Hengstschläger, Markus AU - Pei, Duanqing AU - Cai, Jinglei AU - Nikaido, Toshio AU - Bani-Yaghoub, Mahmud T2 - Stem Cells International SN - 1687-9678 SP - 721538 KW - 5' nucleotidase KW - beta1 integrin KW - endoglin KW - epidermal growth factor KW - fibroblast growth factor KW - Hermes antigen KW - octamer transcription factor 4 KW - scatter factor KW - stage specific embryo antigen 4 KW - Thy 1 antigen KW - tissue scaffold KW - transcription factor NANOG KW - transcription factor Sox2 KW - transforming growth factor KW - acute kidney tubule necrosis KW - amnion KW - amnion fluid KW - bladder injury KW - brain injury KW - brain ischemia KW - cell differentiation KW - cell transplantation KW - diabetes mellitus KW - diaphragm hernia KW - heart failure KW - heart infarction KW - human KW - leg ischemia KW - liver cirrhosis KW - nonhuman KW - paracrine signaling KW - Parkinson disease KW - priority journal KW - protein expression KW - pulmonary hypertension KW - regenerative medicine KW - review KW - sciatic nerve injury KW - skin defect KW - skin graft KW - spinal muscular atrophy KW - stem cell transplantation KW - therapy effect KW - tissue engineering KW - tissue repair AB - The amniotic membrane (AM) and amniotic fluid (AF) have a long history of use in surgical and prenatal diagnostic applications, respectively. In addition, the discovery of cell populations in AM and AF which are widely accessible, nontumorigenic and capable of differentiating into a variety of cell types has stimulated a flurry of research aimed at characterizing the cells and evaluating their potential utility in regenerative medicine. While a major focus of research has been the use of amniotic membrane and fluid in tissue engineering and cell replacement, AM- and AF-derived cells may also have capabilities in protecting and stimulating the repair of injured tissues via paracrine actions, and acting as vectors for biodelivery of exogenous factors to treat injury and diseases. Much progress has been made since the discovery of AM and AF cells with stem cell characteristics nearly a decade ago, but there remain a number of problematic issues stemming from the inherent heterogeneity of these cells as well as inconsistencies in isolation and culturing methods which must be addressed to advance the field towards the development of cell-based therapies. Here, we provide an overview of the recent progress and future perspectives in the use of AM- and AF-derived cells for therapeutic applications. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 532c042a-fd5e-41b6-85ed-3979c29b98ef ER - TY - JOUR TI - The coordinated radio and infrared survey for high-mass star formation (The CORNISH Survey). I. Survey design DO - 10.1086/668058 AU - Hoare, M. G. AU - Purcell, C. R. AU - Churchwell, E. B. AU - Diamond, P. AU - Cotton, W. D. AU - Chandler, C. J. AU - Smethurst, S. AU - Kurtz, S. E. AU - Mundy, L. G. AU - Dougherty, S. M. AU - Fender, R. P. AU - Fuller, G. A. AU - Jackson, J. M. AU - Garrington, S. T. AU - Gledhill, T. R. AU - Goldsmith, P. F. AU - Lumsden, S. L. AU - Martí, J. AU - Moore, T. J. T. AU - Muxlow, T. W. B. AU - Oudmaijer, R. D. AU - Pandian, J. D. AU - Paredes, J. M. AU - Shepherd, D. S. AU - Spencer, R. E. AU - Thompson, M. A. AU - Umana, G. AU - Urquhart, J. S. AU - Zijlstra, A. A. T2 - Publications of the Astronomical Society of the Pacific SN - 0004-6280 VL - 124 IS - 919 SP - 939 EP - 955 AB - We describe the motivation, design, and implementation of the CORNISH survey, an arcsecondresolution radio continuum survey of the inner galactic plane at 5 GHz using the Very Large Array (VLA). It is a blind survey coordinated with the northern Spitzer GLIMPSE I region covering 10° < l < 65° and |b| < 1° at similar resolution. We discuss in detail the strategy that we employed to control the shape of the synthesised beam across this survey, which covers a wide range of fairly low declinations. Two snapshots separated by 4 h kept the beam elongation to less that 1.5 over 75% of the survey area and less than 2 over 98% of the survey. The prime scientific motivation is to provide an unbiased survey for ultra-compact H II regions to study this key phase in massive star formation. A sensitivity around 2 mJy will allow the automatic distinction between radio-loud and radio-quiet mid- IR sources found in the Spitzer surveys. This survey has many legacy applications beyond star formation, including evolved stars, active stars and binaries, and extragalactic sources. The CORNISH survey for compact ionized sources complements other Galactic plane surveys that target diffuse and nonthermal sources, as well as atomic and molecular phases to build up a complete picture of the interstellar medium in the Galaxy. DA - 2012/09/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1d9bc7b9-61d9-4c11-b679-2eacf4482eff ER - TY - JOUR TI - Flow control in an aggressive inter-turbine duct using low profile vortex generators DO - 10.1115/GT2012-69951 AU - Zhang, Yanfeng AU - Hu, Shuzhen AU - Zhang, Xue Feng AU - Benner, Michael AU - Vlasic, Edward T2 - Turbomachinery T2 - Proceedings of the ASME Turbo Expo 2012: GT2012 T3 - ASME Turbo Expo 2012: Turbine Technical Conference and Exposition, GT 2012, June 11-15, 2012, Copenhagen, Denmark SN - 9780791844748 SN - 9780791844748 VL - 8 IS - PARTS A, B and C SP - 1609 EP - 1619 KW - Boundary-layer separation KW - Casing boundary layer KW - Counter-rotating vortices KW - Experimental investigations KW - Flow mechanisms KW - Streamwise vortices KW - Total-pressure loss KW - Vortex generators KW - Boundary layers KW - Ducts KW - Three dimensional KW - Transport aircraft KW - Vortex flow KW - Gas turbines AB - This paper presents the experimental investigation of the flow in an aggressive inter-turbine duct (AITD). The goal is to improve the understanding of the flow mechanisms within the AITD and of the underlying physics of lowprofile vortex generators (LPVGs). The flow structures in the AITD are dominated by counter-rotating vortices and boundary layer separations in both the casing and hub regions. At the first bend of the AITD, the casing boundary layer separates in a 3D mode because of the upstream wakes; this is followed by a massive 2D boundary layer separation. Due to the effect of the radial pressure gradient at the first bend, the streamwise vorticity generated by the casing 3D separation stays close to the casing endwall, and later mixes with the casing counter-rotating vortices formed at the second bend. By using LPVGs with different configurations installed on the casing, the casing boundary layer separation is significantly reduced. The streamwise vortices generated by the LPVGs have the potential to generate another pair of counter-rotating vortices at the AITD second bend, which help to delay/prevent the boundary layer separation. Therefore, the total pressure loss in the AITD was significantly reduced. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3307890f-9e98-4a8d-975e-159d3748d3d2 ER - TY - JOUR TI - Determination of steady state gas turbine operation DO - 10.1115/GT2012-68632 AU - Davison, Craig R. T2 - ASME Turbo Expo 2012: Turbine Technical Conference and Exposition T3 - ASME Turbo Expo 2012: Turbine Technical Conference and Exposition, GT 2012, June 11-15, 2012, Copenhagen, Denmark SN - 9780791844670 VL - 1 SP - 107 EP - 118 KW - Computational time KW - Confidence interval KW - Engine operations KW - Engine performance KW - Indoor test cells KW - Optimal samples KW - Recursive methods KW - Turbine operation KW - Exhibitions KW - Jet engines KW - Gas turbines AB - Repeatable measurement of engine performance requires the system to be near steady state. A technique is presented to assess how close engine operation is to steady state. It estimates the rate of change of the assessed parameter across the sample time and provides an associated confidence interval. This allows a minimum amount of test time to characterize performance and provides consistent criteria to assess steady state. The technique can either be used online to determine when to take a steady state point or to find the optimal sample from a given data set. To make the technique feasible during testing a recursive method is developed to minimize the computational time. The technique is demonstrated on known functions with random noise to benchmark its capabilities. This is followed by a demonstration on test data from a small turbo jet engine operated in an altitude facility, a turboprop on an outdoor test stand and an after-burning turbofan in an indoor test cell. DA - 2012/12/01 PY - 2012 PB - American Society of Mechanical Engineers LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ca6b9347-0c8b-4220-b6eb-8bb45ac224c4 ER - TY - JOUR TI - Novel controller design demonstration for vibration alleviation of helicopter rotor blades DO - 10.1117/12.917520 AU - Ulker, Fatma D. AU - Nitzscheb, Fred T2 - Active and Passive Smart Structures and Integrated Systems 2012 T2 - Proceedings of SPIE T3 - Active and Passive Smart Structures and Integrated Systems 2012, March 12-15, 2012, San Diego, CA, USA SN - 0277-786X SN - 9780819489982 VL - 8341 SP - 834108 KW - Advanced controller KW - Aero-elastic simulations KW - Aerodynamic loading KW - Closed loop stability KW - Computational costs KW - Controller designs KW - Controller synthesis KW - Helicopter vibration control KW - High fidelity KW - Linear matrix inequality formulations KW - Periodic Riccati equation KW - Synthesis problems KW - Trailing edges KW - Integrated control KW - Linear matrix inequalities KW - Riccati equations KW - Turbomachine blades AB - This paper presents an advanced controller design methodology for vibration alleviation of helicopter rotor systems. Particularly, vibration alleviation in a forward ight regime where the rotor blades experience periodically varying aerodynamic loading was investigated. Controller synthesis was carried out under the time-periodic H 2 and H∞ framework and the synthesis problem was solved based on both periodic Riccati and Linear Matrix Inequality (LMI) formulations. The closed-loop stability was analyzed using Floquet-Lyapunov theory, and the controller's performance was validated by closed-loop high-fidelity aeroelastic simulations. To validate the controller's performance an actively controlled trailing edge ap strategy was implemented. Computational cost was compared for both formulations. DA - 2012/04/26 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b6fb9cf4-9e5b-422f-9d57-3267b98921e7 ER - TY - JOUR TI - Rotary wing brown-out symbology: the DVEST test DO - 10.1117/12.922467 AU - Jennings, Sion A. AU - Holst, Peter AU - Craig, Gregory AU - Cheung, Bob T2 - Head- and Helmet-Mounted Displays XVII; and Display Technologies and Applications for Defense, Security, and Avionics VI T2 - Proceedings of SPIE T3 - Head- and Helmet-Mounted Displays XVII; and Display Technologies and Applications for Defense, Security, and Avionics VI, April 25-26, 2012, Baltimore, MD, USA SN - 0277-786X SN - 9780819490612 VL - 8383 SP - 83830G KW - Brown-out KW - Helicopter operation KW - Low visibility KW - Night vision goggles KW - Rotary wing KW - Short-term solutions KW - Situation awareness KW - Symbology KW - Task groups KW - Terrain features KW - Visual environments KW - Accidents KW - Helmet mounted displays KW - Landing KW - Military helicopters KW - Visibility KW - Helicopter services AB - Military helicopter operations encounter degraded visual environments (DVE) on a regular basis. A DVE exists when conditions of low visibility, including those caused by rotor downwash in sand/dust ("brown-out"), snow ("whiteout"/ snowball) or water, obscure both horizon and terrain features. DVE conditions have contributed to the loss of numerous helicopter crews and vehicles in desert operations, including a CH-146 crash during take-off. In Canadian helicopter operations over the past 25 years, "snowball" related events (2 accidents and 54 incidents) outnumbered brown-out related events. A NATO Task Group suggested that specific landing symbology systems could provide an immediate short-term solution that will improve situation awareness and reduce the occurrence of mishaps. This paper describes two symbology systems that were developed and the planned evaluation of these under the Degraded Visual Environment Solution for TacHel (DVEST) Program. DA - 2012/05/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 55dcaa6a-ada3-4b99-baee-5fd50cfad9fe ER - TY - JOUR TI - Water ingress detection in honeycomb sandwich panels by passive infrared thermography using a high-resolution thermal imaging camera DO - 10.1117/12.918567 AU - Ibarra-Castanedo, C. AU - Brault, L. AU - Marcotte, F. AU - Genest, M. AU - Farley, V. AU - Maldague, X. T2 - Thermosense: Thermal Infrared Applications XXXIV T2 - Proceedings of SPIE T3 - Thermosense: Thermal Infrared Applications XXXIV, April 23-26, 2012, Baltimore, MD, USA SN - 0277-786X SN - 9780819490322 VL - 8354 SP - 835405 KW - Aircraft structure KW - Atmospheric conditions KW - Composite layer KW - Core area KW - De-icing agents KW - High resolution KW - Honeycomb sandwich panels KW - Honeycomb sandwich structure KW - Infra-red cameras KW - Mid wave infrared (MWIR) KW - Military aerospace industry KW - Moisture ingress KW - Presence of water KW - Pressure and temperature KW - Thermal imaging cameras KW - Water ingress detection KW - Aerospace industry KW - Aircraft manufacture KW - Airframes KW - Diffusion in liquids KW - Honeycomb structures KW - Infrared devices KW - Infrared radiation KW - Landing KW - Nanocomposite films KW - Sandwich structures KW - Temperature indicating cameras KW - Vapors KW - Thermography (imaging) AB - Water ingress in honeycomb structures is of great concern for the civil and military aerospace industries. Pressure and temperature variations during take-off and landing produce considerable stress on aircraft structures, promoting moisture ingress (by diffusion through fibers or by direct ingress through voids, cracks or unsealed joints) into the core. The presence of water (or other fluids such as kerosene, hydraulic fluid and de-icing agents) in any of its forms (gas vapor, liquid or ice) promotes corrosion, cell breakage, and induce composite layer delaminations and skin disbonds. In this study, testing specimens were produced from unserviceable parts from military aircraft. In order to simulate atmospheric conditions during landing, selected core areas were filled with measured quantities of water and then frozen in a cold chamber. The specimens were then removed from the chamber and monitored for over 20 minutes as they warm up using a cooled high-resolution infrared camera. Results have shown that detection and quantification of water ingress on honeycomb sandwich structures by passive infrared thermography is possible using a HD mid-wave infrared cameras for volumes of water as low as 0.2 ml and from a distance as far as 20 m from the target. DA - 2012/05/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fa5813f6-7179-45c9-8dba-9b51756940f4 ER - TY - JOUR TI - CASTOR: the cosmological advanced survey telescope for optical and ultraviolet research DO - 10.1117/12.926198 AU - Côte, Patrick AU - Scott, Alan AU - Balogh, Michael AU - Buckingham, Ron AU - Aldridge, David AU - Carlberg, Ray AU - Chen, Weiguo AU - Dupuis, Jean AU - Evans, Clinton AU - Drissen, Laurent AU - Fraser, Wes AU - Grandmont, Frederic AU - Harrison, Paul AU - Hutchings, John AU - Kavelaars, J. J. AU - Landry, John-Thomas AU - Lange, Christian AU - Laurin, Denis AU - Patel, Tarun AU - Pillay, Venka AU - Piche, Louis AU - Rader, Andres AU - Robert, Carmelle AU - Sawicki, Marchin AU - Sorba, Robert AU - Theriault, Guillaume AU - Van Waerbeke, Ludovic T2 - Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave T2 - Proceedings of SPIE T3 - Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491435 VL - 8442 SP - 844215 KW - Angular resolution KW - Dark energy KW - Focal Plane KW - Ground based KW - High-resolution imaging KW - Hubble space telescopes KW - Large synoptic survey telescopes KW - Orders of magnitude KW - Spectral region KW - Ultra-violet KW - Astrophysics KW - Millimeter waves KW - Optical design KW - Space telescopes KW - Surveys KW - Optical telescopes AB - The Cosmological Advanced Survey Telescope for Optical and UV Research (CASTOR) is a proposed CSA mission that would make a unique, powerful, and lasting contribution to astrophysics by providing panoramic, high-resolution imaging in the UV/optical (0.15 { 0.55 μm) spectral region. This versatile ̀smallSAT'-class mission would far surpass any ground-based optical telescope in terms of angular resolution, and would provide ultra-deep imaging in three broad filters to supplement longer-wavelength data from planned international dark energy missions (Euclid, WFIRST) as well as from the ground-based Large Synoptic Survey Telescope (LSST). Combining the largest focal plane ever own in space, with an innovative optical design that delivers HST-quality images over a field two orders of magnitude larger than Hubble Space Telescope (HST), CASTOR would image about 1/8th of the sky to a (u-band) depth ̃1 magnitude fainter than will be possible with LSST even after a decade of operations. No planned or proposed astronomical facility would exceed CASTOR in its potential for discovery at these wavelengths. DA - 2012/08/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e46ef02b-1f9d-4eee-8817-b964494bdbc1 ER - TY - JOUR TI - Reference design of deformable mirror electronics for ELT systems DO - 10.1117/12.926405 AU - Caputa, Kris AU - Herriot, Glen AU - Niebergal, Joel AU - Zielinski, Adam T2 - Adaptive Optics Systems III T2 - Proceedings of SPIE T3 - Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491480 VL - 8447 SP - 844767 KW - Deformable mirrors KW - ELT KW - High voltage amplifier KW - NFIRAOS KW - TMT KW - Astrophysics KW - Piezoelectric actuators KW - Voltage regulators KW - Laser pulses AB - One of the first ELT AO systems to be deployed will be NFIRAOS of the Thirty Meter Telescope (TMT). NFIRAOS is currently being designed at the National Research Council of Canada's Herzberg Institute of Astrophysics (HIA). NFIRAOS incorporates deformable mirrors with much larger number of actuators than in current AO systems. To aid the procurement of electronics for NFIRAOS DMs, a reference design is under way at the HIA. We have designed the overall architecture, defined a command communication interface and developed a compact and cost-efficient high voltage amplifier suitable for duplicating in 7673 copies for driving the two NFIRAOS DMs. DA - 2012/09/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d1a20bc0-9d5c-48f1-8d60-aa99ee6fe3f4 ER - TY - JOUR TI - Maximization of signal-to-noise ratio in optical coherence tomography using a depth-dependent matched filter DO - 10.1117/12.2001691 AU - Boroomand, Ameneh AU - Smith, Michael S. D. AU - Popescu, Dan P. AU - Sowa, Michael AU - Sherif, Sherif S. T2 - Photonics North 2012 T2 - Proceedings of SPIE T3 - Photonics North 2012, June 6-8, 2012, Montreal, QC, Canada SN - 0277-786X SN - 9780819490902 VL - 8412 SP - 841202 KW - Depth dependents KW - Empirical estimate KW - OCT images KW - Second order statistics KW - Time domain KW - Vascular tissue KW - Matched filters KW - Signal to noise ratio KW - Tissue KW - Optical tomography AB - We discuss and demonstrate the dependence of noise on the signal in time-domain optical coherence tomography (TD-OCT). We then derive a depth-dependent matched filter to maximize the signal-to-noise ratio at every pixel in a depth-scan (A-scan). We use an empirical estimate of the second order statistics of the noise in OCT images of vascular tissue to implement a depth-dependent filter that is matched to these images. The application of our filter results in an average increase of signal-to-noise ratio of about 7 dB compared to a simple averaging operation. Our filter is not specific to time-domain OCT, but it is applicable to other types of OCT systems. DA - 2012/10/23 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d21ee184-120e-423f-b645-558967cb203c ER - TY - JOUR TI - Towards the simultaneous monitoring of load and damage in aircraft structures using fiber Bragg grating sensors DO - 10.1117/12.975070 AU - Xiao, Gaozhi AU - Guo, Honglei AU - Mrad, Nezih AU - Rocha, Bruno AU - Sun, Zhigang T2 - OFS2012 22nd International Conference on Optical Fiber Sensors T2 - Proceedings of SPIE T3 - 22nd International Conference on Optical Fiber Sensors, October 15-19, 2012, Beijing, China SN - 0277-786X SN - 9780819491039 VL - 8421 SP - 8421BD AB - Load monitoring and damage detection are the two critical aspects of aircraft structural health monitoring (SHM). The load monitoring is achieved by detecting the local strain changes while the damage detection is generally accomplished by the monitoring of acoustic signal changes. It would be ideal that a single sensor can perform both tasks simultaneously. This paper reports the demonstration of using fiber Bragg gratings to monitor load and acoustic signal applied on a simulated aircraft structure. The results clearly show that a single fiber Bragg grating sensor with short grating length has the potential to perform both tasks simultaneously. DA - 2012/10/14 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8335de13-ac59-4480-be17-743e18a0bed0 ER - TY - JOUR TI - Ukpik: testbed for a miniaturized robotic astronomical observatory on a High Arctic mountain DO - 10.1117/12.926598 AU - Steinbring, Eric AU - Leckie, Brian AU - Hardy, Tim AU - Caputa, Kris AU - Fletcher, Murray T2 - Ground-based and Airborne Telescopes IV T2 - Proceedings of SPIE T3 - Ground-Based and Airborne Telescopes IV, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491459 VL - 8444 SP - 84441P AB - Mountains along the northwestern coast of Ellesmere Island, Canada, possess the highest peaks nearest the Pole. This geography, combined with an atmospheric thermal inversion restricted to below ∼1000 m during much of the long arctic night, provides excellent opportunities for uninterrupted cloud-free astronomy - provided the challenges of these incredibly remote locations can be overcome. We present a miniaturized robotic observatory for deployment on a High Arctic mountaintop. This system tested the operability of precise optical instruments during winter, and the logistics of installation and maintenance during summer. It is called Ukpik after the Inuktitut name for the snowy owl, and was deployed at two sites accessible only by helicopter, each north of 82 degrees latitude; one on rock at 1100 m elevation and another on a glacier at 1600 m. The instrument suite included at first an all-sky-viewing camera, with the later addition of a small telescope to monitor Polaris, both protected by a retractable weather-proof enclosure. Expanding this to include a narrow-field drift-scanning camera for studying extra-solar planet transits was also investigated, but not implemented. An unique restriction was that all had to be run on batteries recharged primarily by a wind turbine. Supplementary power came from a methanol fuel-cell electrical generator. Communications were via the Iridium satellite network. The system design, and lessons learned from three years of operation are discussed, along with prospects for time-domain astronomy from isolated, high-elevation polar mountaintops. DA - 2012/07/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2ce47e2e-cd48-4e07-8cb6-ba20b44106ca ER - TY - JOUR TI - Opacity measurements at Summit Camp on Greenland and PEARL in Northern Canada with a 225 GHz tipping radiometer DO - 10.1117/12.925793 AU - Asada, Keiichi AU - Martin-Cocher, Pierre L. AU - Chen, Chien-Ping AU - Matsushita, Satoki AU - Chen, Ming-Tang AU - Huang, Yau-De AU - Inoue, Makoto AU - Ho, Paul T. P. AU - Paine, Scott N. AU - Steinbring, Eric T2 - Ground-based and Airborne Telescopes IV T2 - Proceedings of SPIE T3 - Ground-Based and Airborne Telescopes IV, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491459 VL - 8444 SP - 84441J AB - We report the first measurements of 225 GHz atmospheric opacity at Summit Camp (Latitude 72°.57 N; Longitude 38°.46 W; Altitude 3250 m) in Greenland and the Polar Environment Atmospheric Research Laboratory (PEARL: Latitude 80°.05 N; Longitude 86°.42 W; Altitude 600 m) in Northern Canada with a tipping radiometer. Summit Camp and PEARL are research stations mostly interested in meteorology and geophysics, and they are potentially excellent sites for astronomical observations at sub-millimeter wavelength. We purchased a tipping radiometer from Radiometer Physics GmbH. After a test run at the summit of Mauna Kea, Hawaii, the radiometer was deployed to PEARL in February 2011, and relocated to Summit Camp in August 2011. The atmospheric opacity has been monitored from February 14th to May 10th, 2011 at PEARL and since August 2011 at Summit Camp. The median values of the measured opacity at PEARL ranged from 0.11 in February to 0.19 in May; Summit Camp varied in the range from 0.04 to 0.18 between August 2011 and May 2012. Summit Camp in Greenland is expected to be an excellent site for sub-millimeter and Terahertz astronomy, and we plan to set up there a 12-m telescope for VLBI and single-dish observations. DA - 2012/07/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 34335971-9114-45d1-9e4f-2e4ef15a131f ER - TY - JOUR TI - Haptics-based immersive telerobotic system for improvised explosive device disposal: Are two hands better than one? DO - 10.1117/12.918462 AU - Erickson, David AU - Lacheray, Hervé AU - Lambert, Jason Michel AU - Mantegh, Iraj AU - Crymble, Derry AU - Daly, John AU - Zhao, Yan T2 - Unmanned Systems Technology XIV T2 - Proceedings of SPIE T3 - Unmanned Systems Technology XIV, April 25-27, 2012, Baltimore, MD, Canada SN - 0277-786X SN - 9780819490650 VL - 8387 SP - 838713 AB - State-of-the-art robotic explosive ordnance disposal robotics have not, in general, adopted recent advances in control technology and man-machine interfaces and lag many years behind academia. This paper describes the Haptics-based Immersive Telerobotic System project investigating an immersive telepresence envrionment incorporating advanced vehicle control systems, Augmented immersive sensory feedback, dynamic 3D visual information, and haptic feedback for explosive ordnance disposal operators. The project aim is to provide operatiors a more sophisticated interface and expand sensory input to perform complex tasks to defeat improvised explosive devices successfully. The introduction of haptics and immersive teleprescence has the potential to shift the way teleprescence systems work for explosive ordnance disposal tasks or more widely for first responders scenarios involving remote unmanned ground vehicles. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 00c5c027-c327-430e-9e8f-0e384d4ec8c2 ER - TY - JOUR TI - On the use of a compact optical fiber sensor system in aircraft structural health monitoring DO - 10.1117/12.921041 AU - Mrad, Nezih AU - Guo, Honglei AU - Xiao, Gaozhi AU - Rocha, Bruno AU - Sun, Zhigang T2 - Photonic Applications for Aerospace, Transportation, and Harsh Environment III T2 - Proceedings of SPIE T3 - Photonic Applications for Aerospace, Transportation, and Harsh Environment III, April 23-24, 2012, Baltimore, MD, USA SN - 0277-786X SN - 9780819490469 VL - 8368 SP - 836808 AB - Structural Health Monitoring (SHM) has been identified as an area of significant potential for advanced aircraft maintenance programs that ensure continued airworthiness, enhanced operational safety and reduced life cycle cost. Several sensors and sensory systems have been developed for the implementation of such health monitoring capability. Among a wide range of developed technologies, fiber optic sensor technology, in particular fiber Bragg grating based emerged as one of the most promising for aircraft structural applications. This paper is set to explore the suitability of using a new Fiber Bragg Grating sensor (FBG) system developed for operation in two modes, low and high speed sensing modes, respectively. The suitability of the system for potential use in aircraft load monitoring and damage detection applications has been demonstrated. Results from FBG sensor system were in good agreement with results from conventional resistive strain gauges, validating this capability for load monitoring. For damage detection, the FBG sensor system was able to detect acoustic waves generated 52 inches (1.32 m) away. The initial results, obtained in a full stale experimentation, demonstrate the potential of using FBG sensors for both load monitoring and damage detection in aircraft environment. DA - 2012/04/23 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f8cc7498-dca8-4a88-bc42-3ecfc99e3d18 ER - TY - JOUR TI - TMT adaptive optics program status report DO - 10.1117/12.927046 AU - Ellerbroek, Brent L. AU - Adkins, Sean M. AU - Andersen, David R. AU - Atwood, Jenny AU - Bastard, Arnaud AU - Bo, Yong AU - Boucher, Marc-Andre AU - Boyer, Corinne AU - Byrnes, Peter W. G. AU - Caputa, Kris AU - Chen, Shanqiu AU - Correia, Carlos AU - Cousty, Raphael AU - Fitzsimmons, Joeleff T. AU - Gilles, Luc AU - Gregory, James AU - Herriot, Glen AU - Hickson, Paul AU - Hill, Alexis AU - Pazder, John AU - Pagès, Hubert AU - Pfrommer, Thomas AU - Reshetov, Vladimir A. AU - Roberts, Scott AU - Sinquin, Jean-Christophe AU - Schoeck, Matthias AU - Smith, Malcolm AU - Véran, Jean-Pierre AU - Wang, Lianqi AU - Wei, Kai AU - Wevers, Ivan T2 - Adaptive Optics Systems III T2 - Proceedings of SPIE T3 - Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491480 VL - 8447 SP - 84471J AB - We provide an update on the development of the first light adaptive optics systems for the Thirty Meter Telescope (TMT) over the past two years. The first light AO facility for TMT consists of the Narrow Field Infra-Red AO System (NFIRAOS) and the associated Laser Guide Star Facility (LGSF). This order 60 x 60 laser guide star (LGS) multi-conjugate AO (MCAO) architecture will provide uniform, diffraction-limited performance in the J, H, and K bands over 17-30 arc sec diameter fields with 50 per cent sky coverage at the galactic pole, as is required to support TMT science cases. Both NFIRAOS and the LGSF have successfully completed design reviews during the last twelve months. We also report on recent progress in AO component prototyping, control algorithm development, and system performance analysis. © 2012 SPIE. DA - 2012/07/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c3446e02-43f2-465c-aa90-270ca902df67 ER - TY - JOUR TI - Characterizing near-infrared sky brightness in the Canadian high arctic DO - 10.1117/12.926251 AU - Sivanandam, Suresh AU - Graham, James R. AU - Abraham, Roberto AU - Tekatch, Anthony AU - Steinbring, Eric AU - Ngan, Wayne AU - Welch, Doug L. AU - Law, Nicholas M. T2 - Ground-based and Airborne Instrumentation for Astronomy IV T2 - Proceedings of SPIE T3 - Ground-Based and Airborne Instrumentation for Astronomy IV, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491473 VL - 8446 SP - 844643 AB - We present the first measurements of the near-infrared (NIR), specifically the J-band, sky background in the Canadian High Arctic. There has been considerable recent interest in the development of an astronomical observatory in Ellesmere Island; initial site testing has shown promise for a world-class site. Encouragement for our study came from sky background measurements on the high Antarctic glacial plateau in winter that showed markedly lower NIR emission when compared to good mid-latitude astronomical sites due to reduced emission from the Meinel bands, i.e. hydroxyl radical (OH) airglow lines. This is possibly a Polar effuect and may also be present in the High Arctic. To test this hypothesis, we carried out an experiment which measured the the J-band sky brightness in the High Arctic during winter. We constructed a zenith-pointing, J-band photometer, and installed it at the Polar Environment Atmospheric Research Laboratory (PEARL) near Eureka, Nunavut (latitude: 80° N). We present the design of our ruggedized photometer and our results from our short PEARL observing campaign in February 2012. Taken over a period of four days, our measurements indicate that the J-band sky brightness varies between 15:5-15:9 mag arcsec2; with a measurement uncertainty of 0.15 mag. The uncertainty is entirely dominated by systematic errors present in our radiometric calibration. On our best night, we measured a fairly consistent sky brightness of 15:8 ± 0:15 mag arcsec2: This is not corrected for atmospheric extinction, which is typically < 0:1 mag in the J-band on a good night. The measured sky brightness is comparable to an excellent mid-latitude site, but is not as dark as claimed by the Antarctic measurements. We discuss possible explanations of why we do not see as dark skies as in the Antarctic. Future winter-long sky brightness measurements are anticipated to obtain the necessary statistics to make a proper comparison with the Antarctic measurements. DA - 2012/09/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2c149875-a5f9-401c-8445-6514eff6e96f ER - TY - JOUR TI - A Fresnel propagation analysis of NFIRAOS/IRIS high-contrast exoplanet imaging capabilities DO - 10.1117/12.926826 AU - Marois, Christian AU - Véran, Jean-Pierre AU - Correia, Carlos T2 - Adaptive Optics Systems III T2 - Proceedings of SPIE T3 - Adaptive Optics Systems III, July 1-6, 2012, Amsterdam, Netherlands SN - 0277-786X SN - 9780819491480 VL - 8447 SP - 844726 AB - The thirty meter telescope (TMT) has the potential to find new planetary systems and to study them in greater details. It could also possibly image super-Earth planets around the closest stars or still accreting distant protoplanets around stars in very young star forming regions. Since no first generation dedicated exoplanet finding instrument has been selected for the TMT, initial direct exoplanet imaging will have to rely on the NFIRAOS facility adaptive optics (AO) system and IRIS spectro-imaging near-infrared (NIR) camera. End-to-end Fresnel NFIRAOS simulations are presented using their current optical designs to evaluate the system multi-wavelength high-contrast imaging capabilities. Long exposures have been simulated using the expected AO-corrected phase screens and the estimated speckle lifetime. It is shown that NFIRAOS/IRIS may achieve contrasts close to the Gemini planet imager (GPI, an optimized NIR planet-finding instrument that will soon be installed on the Gemini South 8-m telescope), but needs to rely on multi-wavelength processing (by a factor 50) to achieve that goal, a challenging requirement. Without a coronograph and a better treatment of the in-band static speckle noise, it is unlikely that NFIRAOS/IRIS will be able to achieve GPI-like contrasts at very small inner working angles, which is potentially accessible with a large 30-meter telescope. However, TMT, with its bigger aperture and better angular resolution, along with the current NFIRAOS/IRIS designs, should be able to acquire higher SNR spectra and achieve three times better astrometric accuracy than GPI for medium to bright planets, resulting in better atmospheric characterization and faster orbital parameter determination of a sample of GPI planets. DA - 2012/07/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6d019aa3-ee46-4483-a536-dce0fc3eae73 ER - TY - CHAP TI - Polymer Nanomechanics DO - 10.1016/B978-0-444-53349-4.00184-9 AU - Li, J. K. AU - Li, I. T. S. AU - Walker, G. C. AU - Sullan, R. M. A. AU - Zou, S. AU - Sun, Y. T2 - Polymer Science: A Comprehensive Reference SN - 9780080878621 VL - 7 SP - 377 EP - 404 KW - Adhesion; Atomic force microscopy; Elasticity; Force curve; Force mapping; Hydrophobic hydration; Indentation; Interfacial energy; Microgels; Planar-supported lipid bilayers; Polymer mechanics; Single-molecule force spectroscopy; Viscoelasticity; Young’s modulus AB - The objective of studying the nanoscale mechanical properties and behavior of polymers is to understand how polymeric organized nanostructures respond to forces applied in tension, in compression, and even during fracture. The body of work presented in this review is primarily from our laboratories and covers a breadth of systems and techniques, including atomic force microscopy-based indentation studies on substrate-supported polymeric thin films, microscale hydrogels, force-mapping studies on lipid bilayers, and the mechanics of hydrophobic polymer hydration by single-molecule extension. The elastic response, the contribution of mechanical restructuring, viscosity, and other dissipative effects, as well as interfacial forces, are investigated. DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 374535a9-6a01-47b3-a98e-7116b93c8f20 ER - TY - JOUR TI - Guillain-Barré syndrome-related Campylobacter jejuni in Bangladesh: ganglioside mimicry and cross-reactive antibodies DO - 10.1371/journal.pone.0043976 AU - Islam, Zhahirul AU - Gilbert, Michel AU - Mohammad, Quazi D. AU - Klaij, Kevin AU - Li, Jianjun AU - van Rijs, Wouter AU - Tio-Gillen, Anne P. AU - Talukder, Kaisar A. AU - Willison, Hugh J. AU - van Belkum, Alex AU - Endtz, Hubert P. AU - Jacobs, Bart C. T2 - PLoS ONE SN - 1932-6203 VL - 7 IS - 8 SP - e43976 KW - antibodies KW - Campylobacter KW - enzyme-linked immunoassays KW - immune response KW - glycosyltransferases KW - molecular mimicry KW - monoclonal antibodies KW - serology AB - Background: Campylobacter jejuni is the predominant antecedent infection in Guillain-Barré syndrome (GBS). Molecular mimicry and cross-reactive immune responses to C. jejuni lipo-oligosaccharides (LOS) precipitate the development of GBS, although this mechanism has not been established in patients from developing countries. We determined the carbohydrate mimicry between C. jejuni LOS and gangliosides, and the cross-reactive antibody response in patients with GBS in Bangladesh. Methodology: Sera from 97 GBS patients, and 120 neurological and family controls were tested for antibody reactivity against LOS from C. jejuni isolates from GBS patients in Bangladesh (BD-07, BD-39, BD-10, BD-67 and BD-94) by enzyme-linked immunosorbent assay (ELISA). Cross-reactivity to LOS was determined by ELISA. The LOS outer core structures of C. jejuni strains associated with GBS/MFS were determined by mass spectrometry. Principle Findings: IgG antibodies to LOS from C. jejuni BD-07, BD-39, BD-10, and BD-67 IgG antibodies were found in serum from 56%, 58%, 14% and 15% of GBS patients respectively, as compared to very low frequency (<3%) in controls (p<0.001). Monoclonal antibodies specific for GM1 and GD1a reacted strongly with LOS from the C. jejuni strains (BD-07 and BD-39). Mass spectrometry analysis confirmed the presence of GM1 and GD1a carbohydrate mimics in the LOS from C. jejuni BD-07 and BD-39. Both BD-10 and BD-67 express the same LOS outer core, which appears to be a novel structure displaying GA2 and GD3 mimicry. Up to 90-100% of serum reactivity to gangliosides in two patients (DK-07 and DK-39) was inhibited by 50 μg/ml of LOS from the autologous C. jejuni isolates. However, patient DK-07 developed an anti-GD1a immune response while patient DK-39 developed an anti-GM1 immune response. Conclusion: Carbohydrate mimicry between C. jejuni LOS and gangliosides, and cross-reactive serum antibody precipitate the majority of GBS cases in Bangladesh. DA - 2012/08/27 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 39c38e85-15d3-4dba-b806-432016d780a6 ER - TY - JOUR TI - Ultrafast photocurrent measurement of the escape time of electrons and holes from carbon nanotube p-i-n photodiodes DO - 10.1103/PhysRevLett.108.087404 AU - Gabor, Nathaniel M. AU - Zhong, Zhaohui AU - Bosnick, Ken AU - McEuen, Paul L. T2 - Physical Review Letters SN - 0031-9007 VL - 108 IS - 8 SP - 87404 KW - Applied bias KW - Carrier effective mass KW - Decay time KW - Electrons and holes KW - Escape time KW - Lower energies KW - Photocurrent measurement KW - Photocurrent response KW - Photon energy KW - Pin photodiode KW - Sub-bands KW - Subpicosecond pulse KW - Ultra-fast KW - Variable time delay KW - Carbon nanotubes KW - Photodiodes KW - Photocurrents AB - Ultrafast photocurrent measurements are performed on individual carbon nanotube p-i-n photodiodes. The photocurrent response to subpicosecond pulses separated by a variable time delay Δt shows strong photocurrent suppression when two pulses overlap (Δt=0). The picosecond-scale decay time of photocurrent suppression scales inversely with the applied bias VSD, and is twice as long for photon energy above the second subband E22 as compared to lower energy. The observed photocurrent behavior is well described by an escape time model that accounts for carrier effective mass. DA - 2012/02/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9ccf0b38-8193-4318-89c2-935431793846 ER - TY - JOUR TI - Electron-ion and ion-ion potentials for modeling warm dense matter: applications to laser-heated or shock-compressed Al and Si DO - 10.1103/PhysRevE.86.036407 AU - Dharma-Wardana, M. W. C. T2 - Physical Review E - Statistical, Nonlinear, and Soft Matter Physics SN - 1539-3755 VL - 86 IS - 3 SP - 36407 KW - Attractive Region KW - Classical simulation KW - Electron ions KW - Exchange-correlation correction KW - Higher T KW - Ion temperature KW - Many body wave functions KW - Material property KW - Nonlocal KW - Pair distribution functions KW - Pair interactions KW - Pair potential KW - Phonon hardening KW - Pseudopotentials KW - Quasi-equilibrium KW - Quasi-static KW - Rapid release KW - Static conductivity KW - Temperature evolution KW - Transport coefficient KW - Warm dense matters KW - Aluminum KW - Electron temperature KW - Electrons KW - Hardening KW - Hydrogen KW - Phonons KW - Silicon KW - Thermodynamics KW - Transport properties KW - Wave plasma interactions AB - The pair interactions Uij(r) determine the thermodynamics and linear transport properties of matter via the pair-distribution functions (PDFs), i.e., gij(r). Great simplicity is achieved if Uij(r) could be directly used to predict material properties via classical simulations, avoiding many-body wave functions. Warm dense matter (WDM) is encountered in quasiequilibria where the electron temperature Te differs from the ion temperature Ti, as in laser-heated or in shock-compressed matter. The electron PDFs g ee(r) as perturbed by the ions are used to evaluate fully nonlocal exchange-correlation corrections to the free energy, using hydrogen as an example. Electron-ion potentials for ions with a bound core are discussed with Al and Si as examples, for WDM with Te≠Ti, and valid for times shorter than the electron-ion relaxation time. In some cases the potentials develop attractive regions and then become repulsive and "Yukawa-like" for higher Te. These results clarify the origin of initial phonon hardening and rapid release. Pair potentials for shock-heated WDM show that phonon hardening would not occur in most such systems. Defining meaningful quasiequilibrium static transport coefficients consistent with the dynamic values is addressed. There seems to be no meaningful "static conductivity" obtainable by extrapolating experimental or theoretical σ(ω,Ti,Te) to ω→0, unless Ti→Te as well. Illustrative calculations of quasistatic resistivities R(Ti,Te) of laser-heated as well as shock-heated aluminum and silicon are presented using our pseudopotentials, pair potentials, and classical integral equations. The quasistatic resistivities display clear differences in their temperature evolutions, but are not the strict ω→0 limits of the dynamic values. DA - 2012/09/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 46cc36ab-dda2-40d7-9717-439e8f0afaaf ER - TY - JOUR TI - Structural phase transitions in Si under hydrostatic and uniaxial compression DO - 10.1103/PhysRevB.85.214122 AU - Yao, Yansun AU - Klug, Dennis D. T2 - Physical Review B - Condensed Matter and Materials Physics SN - 1098-0121 VL - 85 IS - 21 SP - 214122 AB - Phase transitions induced by hydrostatic and uniaxial compression of Si are examined using a density functional-based metadynamics method. A metastable Cmcm structure is predicted to form under hydrostatic compression at 300 K in the pressure range near 20 GPa. Enthalpy calculations indicate that this new phase of Si is energetically competitive with the other Si structures found in this pressure range. This phase is shown to be dynamically stable, with a structure closely related to that of the β-Sn and Imma structures previously identified in experiments. Uniaxial compression at 15 GPa and 300 K obtained simple hexagonal Imma and β-Sn structures. The low energy barrier for the formation of the Cmcm structure from the diamond ambient pressure form suggests that this structure may be seen in experiment with the proper experimental conditions. DA - 2012/06/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6d4de861-d896-4a5c-a68a-cf11b70cee9f ER - TY - JOUR TI - Coherent exchange and double beam splitter oscillations in a triple quantum dot DO - 10.1103/PhysRevB.86.045316 AU - Aers, G. C. AU - Studenikin, S. A. AU - Granger, G. AU - Kam, A. AU - Zawadzki, P. AU - Wasilewski, Z. R. AU - Sachrajda, A. S. T2 - Physical Review B - Condensed Matter and Materials Physics SN - 1098-0121 VL - 86 IS - 4 SP - 45316 AB - Recent experiments with an electrostatically gated structure demonstrated coherent oscillations, involving all three spins of a linear triple dot system. In a combined experimental and theoretical study, we demonstrate coherent doublet/doublet exchange oscillations, leading to arbitrary rotation on the relevant Bloch sphere, and we reveal an interplay between exchange and hyperfine-driven "double coherent beam splitter" oscillations. DA - 2012/07/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : da566a57-4c2e-41c0-a1ed-cd1452ac2412 ER - TY - JOUR TI - High-pressure phases of lithium borohydride LiBH4: a first-principles study DO - 10.1103/PhysRevB.86.064107 AU - Yao, Yansun AU - Klug, Dennis D. T2 - Physical Review B - Condensed Matter and Materials Physics SN - 1098-0121 VL - 86 IS - 6 SP - 64107 AB - High-pressure phase transformations in LiBH 4 were theoretically investigated using first-principles density functional methods. A series of pressure-induced structural transformations are predicted in LiBH 4, as Pnma (phase II) → I4 1/acd (phase III) → NaCl type (phase V) → NiAs type (phase VI) → polymeric forms. The calculated pressures for the II → III transition and the III → V transition are 0.9 and 27 GPa, respectively, and both agree very well with recent experimental observations. A B1-B8 transformation becomes more favored at higher pressure, and this results in a distorted NiAs structure of LiBH 4. Denoted as phase VI, the distorted NiAs structure is the lowest enthalpy phase of LiBH 4 above 60 GPa and confirmed to be dynamically stable by phonon calculations. The ionic character and band gap of the phase VI decreases with increasing pressure. At still higher pressures, the extended structures formed by polymeric BH 4 layers intercalated by Liδ + cations may exist, and these represent the metallic forms of LiBH 4. Published by the American Physical Society. DA - 2012/08/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 444d0a13-412a-4de4-919f-1ed16c999faa ER - TY - JOUR TI - Nonlinear magnetotransport phenomena in high-mobility two-dimensional electrons in InGaAs/InP and GaAs/AlGaAs DO - 10.1103/PhysRevB.86.115309 AU - Studenikin, S. A. AU - Granger, G. AU - Kam, A. AU - Sachrajda, A. S. AU - Wasilewski, Z. R. AU - Poole, P. J. T2 - Physical Review B - Condensed Matter and Materials Physics SN - 1098-0121 VL - 86 IS - 11 SP - 115309 AB - This paper reports on the observation and analysis of magnetotransport phenomena in the nonlinear differential resistance rxx=dVxx/dI of high-mobility In xGa 1-xAs/InP and GaAs/Al xGa 1-xAs Hall bar samples driven by direct current I dc. Specifically, it is observed that Shubnikov-de Haas (SdH) oscillations at large filling factors invert their phase at sufficiently large values of Idc. This phase inversion is explained as being due to an electron heating effect. In the quantum Hall effect regime the rxx oscillations transform into diamond-shaped patterns with different slopes corresponding to odd and even filling factors. The diamond-shaped features at odd filling factors can be used as a probe to determine spin energy gaps. A zero current anomaly (ZCA) which manifests itself as a narrow dip in the rxx(Idc) characteristics at zero current is also observed. The ZCA effect strongly depends upon temperature, vanishing above 1 K while the transport diamonds persist to higher temperatures. The transport diamonds and ZCA are fully reproduced in a higher mobility GaAs/AlGaAs Hall bar structure confirming that these phenomena reflect intrinsic properties of two-dimensional systems. DA - 2012/09/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 503fb0e7-8d63-49fe-b58a-108eb96921ed ER - TY - JOUR TI - Microwave-induced resistance oscillations in tilted magnetic fields DO - 10.1103/PhysRevB.86.235305 AU - Bogan, A. AU - Hatke, A. T. AU - Studenikin, S. A. AU - Sachrajda, A. AU - Zudov, M. A. AU - Pfeiffer, L. N. AU - West, K. W. T2 - Physical Review B - Condensed Matter and Materials Physics SN - 1098-0121 VL - 86 IS - 23 SP - 235305 AB - We have studied the effect of an in-plane magnetic field on microwave-induced resistance oscillations in a high mobility two-dimensional electron system. We have found that the oscillation amplitude decays exponentially with an in-plane component of the magnetic field B1. While these findings cannot be accounted for by existing theories, our analysis suggests that the decay can be explained by a B1-induced correction to the quantum scattering rate, which is quadratic in B1. DA - 2012/12/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cd212e20-8d19-48c1-a4d9-3bb8880d903a ER - TY - JOUR TI - Molecular alignment and orientation with a hybrid Raman scattering technique DO - 10.1103/PhysRevA.86.053419 AU - Bustard, Philip J. AU - Lausten, R. AU - Sussman, Benjamin J. T2 - Physical Review A - Atomic, Molecular, and Optical Physics SN - 1050-2947 VL - 86 IS - 5 SP - 53419 KW - Amplification factors KW - Analytic theory KW - Angular momentum orientation KW - Coherent dynamics KW - Molecular hydrogen KW - Nonresonant dynamic Stark effects KW - Physical societies KW - Pump pulse KW - Scattering techniques KW - Vacuum fluctuations KW - Amplification KW - Angular momentum KW - Optical pumping AB - We demonstrate a scheme for the preparation of molecular alignment and angular momentum orientation using a hybrid combination of two limits of Raman scattering. First a weak, impulsive pump pulse initializes the system via the nonresonant dynamic Stark effect. Then, having overcome the influence of the vacuum fluctuations, an amplification pulse selectively enhances the initial coherences by transient stimulated Raman scattering, generating alignment and angular momentum orientation of molecular hydrogen. The amplitude and phase of the resulting coherent dynamics are experimentally probed, indicating an amplification factor of 4.5. An analytic theory is developed to model the dynamics. DA - 2012/11/26 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d801e383-88c5-4ad7-b9fc-8f908e5db1da ER - TY - JOUR TI - Highly tolerant tunable waveguide polarization rotator scheme DO - 10.1364/OL.37.003534 AU - Alonso-Ramos, C. AU - Halir, R. AU - Ortega-Moñux, A. AU - Cheben, P. AU - Vivien, L. AU - Molina-Fernández, Í. AU - Marris-Morini, D. AU - Janz, S. AU - Xu, D.-X. AU - Schmid, J. T2 - Optics Letters SN - 0146-9592 VL - 37 IS - 17 SP - 3534 EP - 3536 KW - Extinction ratios KW - Fabrication errors KW - Fabrication tolerances KW - Polarization conversion KW - Polarization extinction ratio KW - Polarization rotator KW - Silicon on insulator KW - Tunable wave-guides KW - Wavelength tunability KW - Wavelength tuning KW - Errors KW - Fabrication KW - Optical communication AB - Integrated polarization rotators are known to exhibit stringent fabrication tolerances, which severely handicap their practical application. Here we present a general polarization rotator scheme that enables both the compensation of fabrication errors and wavelength tunability. The scheme is described analytically, and a condition for perfect polarization conversion is established. Simulations of a silicon-on-insulator polarization rotator show polarization extinction ratios in excess of 40 dB even in the presence of large fabrication errors that in a conventional rotator configuration degrade the extinction ratio to below 5 dB. Additionally, wavelength tuning over ±30 nm is shown. DA - 2012/08/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 73bbab35-cac6-409f-b543-b7975d2cee1b ER - TY - JOUR TI - Polarization-independent grating coupler for micrometric silicon rib waveguides DO - 10.1364/OL.37.003663 AU - Alonso-Ramos, C. AU - Zavargo-Peche, L. AU - Ortega-Moñux, A. AU - Halir, R. AU - Molina-Fernández, I. AU - Cheben, P. T2 - Optics Letters SN - 0146-9592 VL - 37 IS - 17 SP - 3663 EP - 3665 KW - Coupling efficiency KW - Directivity KW - Dual-polarizations KW - Duty cycles KW - Fiber chip coupling KW - Grating couplers KW - Grating pitch KW - High reflectivity KW - Oxide thickness KW - Polarization dependence KW - Polarization-independent KW - Practical implementation KW - Selective removal KW - Si substrates KW - Silicon on insulator waveguide KW - Silicon rib waveguides KW - Waveguides KW - Polarization AB - Grating couplers are a promising approach to implement efficient fiber-chip coupling. However, their strong polarization dependence makes dual-polarization operation challenging. In this Letter we propose, for the first time, a polarization-independent grating coupler for thick rib silicon-on-insulator (SOI) waveguides. Coupling efficiency is optimized by designing the grating pitch and duty cycle, without varying the bottom oxide thickness, which significantly simplifies practical implementation. Directivity of the grating coupler is enhanced by a high reflectivity layer under the bottom oxide after the selective removal of the Si substrate. Dual-polarization coupling efficiency of -2.8 dB is shown. DA - 2012/08/29 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 38b28ac8-c949-48f0-b90d-42b3f153c4f4 ER - TY - JOUR TI - Measurement of the transverse electric field profile of light by a self-referencing method with direct phase determination DO - 10.1364/OE.20.002034 AU - Bamber, C. AU - Sutherland, B. AU - Patel, A. AU - Stewart, C. AU - Lundeen, J. S. T2 - Optics Express SN - 1094-4087 VL - 20 IS - 3 SP - 2034 EP - 2044 AB - We present a method for measuring the transverse electric field profile of a beam of light which allows for direct phase retrieval. The measured values correspond, within a normalization constant, to the real and imaginary parts of the electric field in a plane normal to the direction of propagation. This technique represents a self-referencing method for probing the wavefront characteristics of light. DA - 2012/01/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1196a3e2-6c0b-44c2-b666-85e125ae6edd ER - TY - JOUR TI - Slowing light down by low magnetic fields: pulse delay by transient spectral hole-burning in ruby DO - 10.1364/OE.20.019039 AU - Riesen, Hans AU - Rebane, Aleksander K. AU - Szabo, Alex AU - Carceller, Ivana T2 - Optics Express SN - 1094-4087 VL - 20 IS - 17 SP - 19039 EP - 19049 KW - External magnetic field KW - Gaussian pulse KW - Group velocities KW - Hole burning KW - Linear spectral KW - Low magnetic fields KW - Pulse delay KW - Pulse distortion KW - Spectral-hole burning KW - Spectroscopic technique KW - Chromium compounds KW - Magnetic fields KW - Ruby KW - Slow light KW - Computer simulation KW - Radiation scattering KW - Refractometry AB - We report on the observation of slow light induced by transient spectral hole-burning in a solidthat is based on excited-state population storage. Experiments were conducted in the R1-line (2E-4A2 transition) of a 2.3 mm thick pink ruby (Al2O3:Cr(III) 130 ppm). Importantlythe pulse delay can be controlled by the application of a low external magnetic field B||c≪9 mT and delays of up to 11 ns with minimal pulse distortion are observed for ∼55 ns Gaussian pulses. The delay corresponds to a group velocity value of ∼c/1400. The experiment is very well modelled by linear spectral filter theory and the results indicate the possibility of using transient hole-burning based slow light experiments as a spectroscopic technique. DA - 2012/08/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5b542ae1-c6be-4e2e-9580-4f9e5d52493e ER - TY - JOUR TI - Hadamard multiplexing in laser ultrasonics DO - 10.1364/OE.20.025798 AU - Rousseau, Guy AU - Blouin, Alain T2 - Optics Express SN - 1094-4087 VL - 20 IS - 23 SP - 25798 EP - 25816 KW - Hadamard multiplexing KW - Laser intensities KW - Laser ultrasonics KW - Non-contact ultrasonic inspection KW - Pulse echoes KW - Shot-noise level KW - Signaltonoise ratio (SNR) KW - Spatial intensity distribution KW - Surface damages KW - Synthetic aperture focusing techniques KW - Chemical detection KW - Detectors KW - Laser beams KW - Shot noise KW - Signal detection KW - Signal to noise ratio AB - In state-of-the-art laser ultrasonics (LU), the signal-to-noise ratio (SNR) is limited by the shot noise of the detected laser radiation. Further improving the SNR then requires averaging multiple signals or increasing generation and/or detection laser intensities. The former strategy is time consuming and the latter leads to surface damages. For signal-independent limiting noises, Hadamard multiplexing increases the SNR by averaging multiple signals in parallel using a single detector. Here we consider the use of Hadamard multiplexing in LU for the non-contact ultrasonic inspection of materials. By using 31 element Hadamard masks to modulate the spatial intensity distribution of the generation laser beam, the measured SNR is improved by a factor 2.8, in good agreement with the expected multiplexing or Fellgett advantage. In contrast to many other applications of Hadamard multiplexing, the SNR is improved for shot-noise-limited measurements since the shot noise level is independent of the signal in LU. The Hadamard multiplexing of the detection laser beam is also considered but can only lead to a throughput or Jacquinot advantage. However, for pulse-echo LU, the Hadamard multiplexing of both generation and detection laser beams allows using the synthetic aperture focusing technique (SAFT). DA - 2012/10/31 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1e4b6963-fcf6-4392-af16-a95c1e21310e ER - TY - JOUR TI - Simultaneous retrieval of fluidic refractive index and surface adsorbed molecular film thickness using silicon wire waveguide biosensors DO - 10.1364/OE.20.026969 AU - Atsumi, Yuki AU - Xu, Dan-Xia AU - Delâge, André AU - Schmid, Jens H. AU - Vachon, Martin AU - Cheben, Pavel AU - Janz, Siegfried AU - Nishiyama, Nobuhiko AU - Arai, Shigehisa T2 - Optics Express SN - 1094-4087 VL - 20 IS - 24 SP - 26969 EP - 26977 AB - For silicon wire based ring resonator biosensors, we investigate the simultaneous retrieval of changes in the fluidic refractive index Δn c and surface adsorbed molecular film thickness ΔdF. This can be achieved by monitoring the resonance shifts of the sensors operating in the TE and TM polarizations at the same time. Although this procedure is straightforward in principle, significant retrieval errors can be introduced due to deviations in the sensor waveguide cross-sections from their nominal values in the range commonly encountered for silicon photonic wire devices. We propose a method of determining the fabricated waveguide size using the group indices derived from measured free spectral range (FSR) of the resonators. We further demonstrate that using experimentally measured group index values, the waveguide size can be determined to accuracies of ± 2 nm in width and ± 1 nm in height. By using this procedure, Δn c and ΔdF can be obtained to a precision of within 10% of the true values using optically measurable parameters, improving the retrieval accuracy by more than 3 times. DA - 2012/11/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 593928fd-2209-4c37-a3b3-e5f1d8f28b59 ER - TY - JOUR TI - NeuroTouch: a physics-based virtual simulator for cranial microneurosurgery training DO - 10.1227/NEU.0b013e318249c744 AU - Delorme, Sébastien AU - Laroche, Denis AU - DiRaddo, Robert AU - F. Del Maestro, Rolando T2 - Neurosurgery SN - 0148-396X VL - 71 IS - Operative Neurosurgery SP - ons32 EP - ons42 KW - Computer simulation, Craniotomy, Neurosurgery, Teaching, Training AB - BACKGROUND: A virtual reality neurosurgery simulator with haptic feedback may help in the training and assessment of technical skills requiring the use of tactile and visual cues. OBJECTIVE: To develop a simulator for craniotomy-based procedures with haptic and graphics feedback for implementation by universities and hospitals in the neurosurgery training curriculum. METHODS: NeuroTouch was developed by a team of more than 50 experts from the National Research Council Canada in collaboration with surgeons from more than 20 teaching hospitals across Canada. Its main components are a stereovision system, bimanual haptic tool manipulators, and a high-end computer. The simulation software engine runs 3 processes for computing graphics, haptics, and mechanics. Training tasks were built from magnetic resonance imaging scans of patients with brain tumors. RESULTS: Two training tasks were implemented for practicing skills with 3 different surgical tools. In the tumor-debulking task, the objective is complete tumor removal without removing normal tissue, using the regular surgical aspirator (suction) and the ultrasonic aspirator. The objective of the tumor cauterization task is to remove a vascularized tumor with an aspirator while controlling blood loss using bipolar electrocautery. CONCLUSION: NeuroTouch prototypes have been set up in 7 teaching hospitals across Canada, to be used for beta testing and validation and evaluated for integration in a neurosurgery training curriculum. DA - 2012/09/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : de1551c4-7060-4dc0-a563-3ca634939fee ER - TY - JOUR TI - Tailored SWCNT functionalization optimized for compatibility with epoxy matrices DO - 10.1088/0957-4484/23/28/285701 AU - Martinez-Rubi, Y. AU - Gonzalez-Dominguez, J. M. AU - Ansón-Casaos, A. AU - Kingston, C. T. AU - Daroszewska, M. AU - Barnes, M. AU - Hubert, P. AU - Cattin, C. AU - Martinez, M. T. AU - Simard, B. T2 - Nanotechnology SN - 0957-4484 VL - 23 IS - 28 SP - 285701 KW - Arc-discharge method KW - Characterization techniques KW - Chemical functionalization KW - Coupling reaction KW - Direct integration KW - Epoxy matrices KW - FTIR KW - Interface interaction KW - Rheology measurement KW - Chemical bonds KW - Electronic properties KW - Functional groups KW - Molecular weight KW - Oligomers KW - Optical microscopy KW - Thermogravimetric analysis KW - Thermosets KW - Fourier transform infrared spectroscopy AB - We have modified single walled carbon nanotubes (SWCNTs) with well defined matrix-based architectures to improve interface interaction in SWCNT/epoxy composites. The hardener and two pre-synthesized oligomers containing epoxy and hardener moieties were covalently attached to the SWCNT walls by insitu diazonium or carboxylic coupling reactions. In this way, SWCNTs bearing amine or epoxide-terminated fragments of different molecular weights, which resemble the chemical structure of the cured resin, were synthesized. A combination of characterization techniques such as Raman and infrared absorption (FTIR) spectroscopy, elemental analysis and coupled thermogravimetry-FTIR spectroscopy were used to identify both the functional groups and degree of functionalization of SWCNTs synthesized by the laser ablation and arc-discharge methods. Depending on the type of reaction employed for the chemical functionalization and the molecular weight of the attached fragment, it was possible to control the degree of functionalization and the electronic properties of the functionalized SWCNTs. Improved dispersion of SWCNTs in the epoxy matrix was achieved by direct integration without using solvents, as observed from optical microscopy and rheology measurements of the SWCNT/epoxy mixtures. Composite materials using these fillers are expected to exhibit improved properties while preserving the thermosetting architecture. © 2012 IOP Publishing Ltd. DA - 2012/06/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 82023bc6-06ea-403c-a1d0-5bda8c05622e ER - TY - JOUR TI - Interplay between crystal phase purity and radial growth in InP nanowires DO - 10.1088/0957-4484/23/38/385205 AU - Poole, P. J. AU - Dalacu, D. AU - Wu, X. AU - Lapointe, J. AU - Mnaymneh, K. T2 - Nanotechnology SN - 0957-4484 VL - 23 IS - 38 SP - 385205 KW - Condensed matter: electrical, magnetic and optical; Semiconductors; Surfaces, interfaces and thin films; Condensed matter: structural, mechanical & thermal; Nanoscale science and low-D systems AB - The interplay between crystal phase purity and radial growth in InP nanowires is investigated. By modifying the growth rate and V/III ratio, regions of high or low stacking fault density can be controllably introduced into wurtzite nanowires. It is found that regions with high stacking fault density encourage radial growth. Through careful choice of growth conditions pure wurtzite InP nanowires are then grown which exhibit narrow 4.2K photoluminescence linewidths of 3.7meV at 1.490meV, and no evidence of emission related to stacking faults or zincblende insertions. DA - 2012/09/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 76109713-d1b9-4318-9542-1bc940bce10d ER - TY - JOUR TI - HR5907: discovery of the most rapidly rotating magnetic early B-type star by the MiMeS Collaboration DO - 10.1111/j.1365-2966.2011.19824.x AU - Grunhut, J. H. AU - Rivinius, T. AU - Wade, G. A. AU - Townsend, R. H. D. AU - Marcolino, W. L. F. AU - Bohlender, D. A. AU - Szeifert, T. AU - Petit, V. AU - Matthews, J. M. AU - Rowe, J. F. AU - Moffat, A. F. J. AU - Kallinger, T. AU - Kuschnig, R. AU - Guenther, D. B. AU - Rucinski, S. M. AU - Sasselov, D. AU - Weiss, W. W. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 419 IS - 2 SP - 1610 EP - 1627 AB - We report the discovery and analysis of a very strong magnetic field in the rapidly rotating early B-type star HR5907, based on observations obtained as part of the Magnetism in Massive Stars (MiMeS) project. We infer a rotation period of 0.508276 +0.000015 -0.000012d from photometric and Hα EW measurements, making this the shortest period, non-degenerate, magnetic massive star known to date. From the comparison of IUE UV and optical spectroscopy with LTE bruce/kylie models we find a solid-angle integrated, uniform black-body temperature of 17000 ± 1000K, a projected rotational velocity of 290 ± 10kms -1, an equatorial radius of 3.1 ± 0.2R ⊙, a stellar mass of 5.5 ± 0.5M ⊙, and an inclination angle of the rotation axis to our line-of-sight of 70 ± 10°. Our measurements of the longitudinal magnetic field, which vary between -500 and -2000G, phase coherently with the rotation period and imply a surface dipole field strength of ∼15.7kG. On the other hand, from fits to mean Least-Squares Deconvolved Stokes V line profiles we infer a dipole field strength of ∼10.4kG. This disagreement may result from a magnetic configuration more complex than our model, and/or from the non-uniform helium surface abundance distribution. In either case we obtain a magnetic obliquity nearly aligned with the rotation axis Our optical spectroscopy also shows weak variability in carbon, silicon and nitrogen lines. The emission variability in hydrogen Balmer and Paschen lines indicates the presence of a dense, highly structured magnetosphere, interpreted as a centrifugally supported, magnetically confined circumstellar disc. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : af776666-1c70-47a4-b000-407ad737aa7b ER - TY - JOUR TI - Coplanar circumbinary debris discs DO - 10.1111/j.1365-2966.2012.21865.x AU - Kennedy, G. M. AU - Wyatt, M. C. AU - Sibthorpe, B. AU - Phillips, N. M. AU - Matthews, B. C. AU - Greaves, J. S. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 426 IS - 3 SP - 2115 EP - 2128 AB - We present resolved Herschel images of circumbinary debris discs in the α CrB (HD 139006) and β Tri (HD13161) systems. By modelling their structure, we find that both discs are consistent with being aligned with the binary orbital planes. Though secular perturbations from the binary can bring the disc into alignment, in both cases the alignment time at the distances at which the disc is resolved is greater than the stellar age, so we conclude that the coplanarity was primordial. Neither disc can be modelled as a narrow ring, requiring extended radial distributions. To satisfy both the Herschel and mid-infrared images of the α CrB disc, we construct a model that extends from 1 to 300 au, whose radial profile is broadly consistent with a picture where planetesimal collisions are excited by secular perturbations from the binary. However, this model is also consistent with stirring by other mechanisms, such as the formation of Pluto-sized objects. The β Tri disc is modelled as a disc that extends from 50 to 400 au. A model with depleted (rather than empty) inner regions also reproduces the observations and is consistent with binary and other stirring mechanisms. As part of the modelling process, we find that the Herschel PACS (Photodetector and Array Camera & Spectrometer) beam varies by as much as 10 per cent at 70 μm and a few per cent at 100 μm. The 70 μm variation can therefore hinder image interpretation, particularly for poorly resolved objects. The number of systems in which circumbinary debris disc orientations have been compared with the binary plane is now 4. More systems are needed, but a picture in which discs around very close binaries (α CrB, β Tri and HD 98800, with periods of a few weeks to a year) are aligned, and discs around wider binaries (99 Her, with a period of 50 yr) are misaligned, may be emerging. This picture is qualitatively consistent with the expectation that the protoplanetary discs from which the debris emerged are more likely to be aligned if their binaries have shorter periods. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 221599f9-5f45-46db-8f63-85aa6f6cb7a4 ER - TY - JOUR TI - SiMPE: 7th Workshop on speech and sound in mobile and pervasive environments DO - 10.1145/2371664.2371727 AU - Nanavati, Amit A. AU - Rajput, Nitendra AU - Rudnicky, Alexander AU - Turunen, Markku AU - Sandholm, Thomas AU - Munteanu, Cosmin AU - Penn, Gerald T2 - MobileHCI'12 - Companion Proceedings of the 14th International Conference on Human Computer Interaction with Mobile Devices and Services T3 - 2012 14th ACM International Conference on Human-Computer Interaction with Mobile Devices and Services, MobileHCI'12, September 21-24, 2012, San Francisco, CA, USA SN - 978-1-4503-1105-2 SN - 978-1-4503-1443-5 SP - 251 EP - 253 KW - Audio interaction KW - Developing regions KW - Embedded device KW - Multi-Modal Interactions KW - Multi-modality KW - Pervasive environments KW - Previous year KW - Sound processing KW - User interaction KW - Acoustic waves KW - Human computer interaction KW - Mobile computing KW - Mobile devices KW - Speech processing KW - Ubiquitous computing KW - Audio acoustics AB - The SiMPE workshop series started in 2006 [2] with the goal of enabling speech processing on mobile and embedded devices to meet the challenges of pervasive environments (such as noise) and leveraging the context they offer (such as location). SiMPE 2010 and 2011 brought together researchers from the speech and the HCI communities. Multimodality got more attention in SiMPE 2008 than it had received in the previous years. In SiMPE 2007, the focus was on developing regions. Speech User interaction in cars was a focus area in 2009. With SiMPE 2012, the 7th in the series, we hope to explore the area of speech along with sound. When using the mobile in an eyes-free manner, it is natural and convenient to hear about notifications and events. The arrival of an SMS has used a very simple sound based notification for a long time now. The technologies underlying speech processing and sound processing are quite different and these communities have been working mostly independent of each other. And yet, for multimodal interactions on the mobile, it is perhaps natural to ask whether and how speech and sound can be mixed and used more effectively and naturally. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d6f5521d-91a8-4ceb-a351-e01947a0fae3 ER - TY - JOUR TI - Reconciling Planck constant determinations via watt balance and enriched-silicon measurements at NRC Canada DO - 10.1088/0026-1394/49/1/L03 AU - Steele, A. G. AU - Meija, J. AU - Sanchez, C. A. AU - Yang, L. AU - Wood, B. M. AU - Sturgeon, R. E. AU - Mester, Z. AU - Inglis, A. D. T2 - Metrologia SN - 0026-1394 VL - 49 IS - 1 SP - L8 EP - L10 KW - Avogadro constant KW - Boltzmann constants KW - Elementary charge KW - Equivalence principles KW - Fundamental constants KW - High precision KW - Mechanical force KW - Parts per billion KW - Planck constants KW - Single atoms KW - Watt balance KW - Engineering KW - Metallurgical engineering KW - Metric system AB - The next revision to the International System of Units will emphasize the relationship between the base units (kilogram, metre, second, ampere, kelvin, candela and mole) and fundamental constants of nature (the speed of light, c, the Planck constant, h, the elementary charge, e, the Boltzmann constant, k B, the Avogadro constant, N A, etc). The redefinition cannot proceed without consistency between two complementary metrological approaches to measuring h: a 'physics' approach, using watt balances and the equivalence principle between electrical and mechanical force, and a 'chemistry' approach that can be viewed as determining the mass of a single atom of silicon. We report the first high precision physics and chemistry results that agree within 12 parts per billion: h (watt balance) = 6.626 070 63(43) × 10 -34Js and h(silicon) = 6.626 070 55(21) × 10 -34Js. When combined with values determined by other metrology laboratories, this work helps to constrain our knowledge of h to 20 parts per billion, moving us closer to a redefinition of the metric system used around the world. © 2012 BIPM & IOP Publishing Ltd. DA - 2012/01/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4bfa23b0-263d-482c-914b-869862aca8ef ER - TY - JOUR TI - Investigation of low-temperature fixed points by an international star intercomparison of sealed triple-point cells DO - 10.1088/0026-1394/49/3/257 AU - Fellmuth, B. AU - Wolber, L. AU - Head, D. I. AU - Hermier, Y. AU - Hill, K. D. AU - Nakano, T. AU - Pavese, F. AU - Peruzzi, A. AU - Rusby, R. L. AU - Shkraba, V. AU - Steele, A. G. AU - Steur, P. P. M. AU - Szmyrka-Grzebyk, A. AU - Tew, W. L. AU - Wang, L. AU - White, D. R. T2 - Metrologia SN - 0026-1394 VL - 49 IS - 3 SP - 257 EP - 265 KW - Experimental equipments KW - Filling technologies KW - Fixed points KW - Gas sources KW - Intercomparisons KW - International Temperature Scale of 1990 KW - Low temperatures KW - Measurement programs KW - Melting curves KW - Thermal behaviours KW - Triple points KW - Argon KW - Hydrogen KW - Neon KW - Stars KW - Temperature KW - Source separation AB - An overview of the results of an international star intercomparison of low-temperature fixed points is given. Between 1997 and 2005, 68 sealed triple-point cells (STPCs) of the twelve laboratories represented by the authors were investigated at PTB. The STPCs are used to realize the triple points of hydrogen, neon, oxygen and argon as defining fixed points of the International Temperature Scale of 1990, ITS-90. The melting curves (MCs) of all STPCs have been measured on the same experimental equipment, adhering strictly to a single measurement program. This protocol enables separation of the effects influencing the MCs and direct comparison of the thermal behaviour of the STPCs, which are quite different with respect to design, age, gas source and filling technology. In the paper, special emphasis is given to the spread of the liquidus-point temperatures and to the uncertainty of their determination. Connections between the star intercomparison and completed and ongoing international activities are also discussed. © 2012 BIPM & IOP Publishing Ltd. DA - 2012/03/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : aaa4fb58-69a9-4536-8e32-622513b075db ER - TY - JOUR TI - The 8th international comparison of absolute gravimeters 2009: the first key comparison (CCM.G-K1) in the field of absolute gravimetry DO - 10.1088/0026-1394/49/6/666 AU - Jiang, Z. AU - Pálinkáš, V. AU - Arias, F.E. AU - Liard, J. AU - Merlet, S. AU - Wilmes, H. AU - Vitushkin, L. AU - Robertsson, L. AU - Tisserand, L. AU - Pereira Dos Santos, F. AU - Bodart, Q. AU - Falk, R. AU - Baumann, H. AU - Mizushima, S. AU - Mäkinen, J. AU - Bilker-Koivula, M. AU - Lee, C. AU - Choi, I.M. AU - Karaboce, B. AU - Ji, W. AU - Wu, Q. AU - Ruess, D. AU - Ullrich, C. AU - Kostelecký, J. AU - Schmerge, D. AU - Eckl, M. AU - Timmen, L. AU - Le Moigne, N. AU - Bayer, R. AU - Olszak, T. AU - Ågren, J. AU - Del Negro, C. AU - Greco, F. AU - Diament, M. AU - Deroussi, S. AU - Bonvalot, S. AU - Krynski, J. AU - Sekowski, M. AU - Hu, H. AU - Wang, L.J. AU - Svitlov, S. AU - Germak, A. AU - Francis, O. AU - Becker, M. AU - Inglis, D. AU - Robinson, I. T2 - Metrologia SN - 0026-1394 VL - 49 IS - 6 SP - 666 EP - 684 KW - Absolute gravimeter KW - Absolute gravimetry KW - Absolute gravity KW - CIPM MRA KW - Gravity survey KW - High-precision KW - International Committee for Weights and Measures KW - International comparison KW - Key comparison KW - Mutual recognition arrangements KW - National metrology institutes KW - Pilot studies KW - Watt balance KW - Data processing KW - Metric system KW - Gravimeters AB - The 8th International Comparison of Absolute Gravimeters (ICAG2009) took place at the headquarters of the International Bureau of Weights and Measures (BIPM) from September to October 2009. It was the first ICAG organized as a key comparison in the framework of the CIPM Mutual Recognition Arrangement of the International Committee for Weights and Measures (CIPM MRA) (CIPM 1999). ICAG2009 was composed of a Key Comparison (KC) as defined by the CIPM MRA, organized by the Consultative Committee for Mass and Related Quantities (CCM) and designated as CCM.G-K1. Participating gravimeters and their operators came from national metrology institutes (NMIs) or their designated institutes (DIs) as defined by the CIPM MRA. A Pilot Study (PS) was run in parallel in order to include gravimeters and their operators from other institutes which, while not signatories of the CIPM MRA, nevertheless play important roles in international gravimetry measurements. The aim of the CIPM MRA is to have international acceptance of the measurement capabilities of the participating institutes in various fields of metrology. The results of CCM.G-K1 thus constitute an accurate and consistent gravity reference traceable to the SI (International System of Units), which can be used as the global basis for geodetic, geophysical and metrological observations of gravity. The measurements performed afterwards by the KC participants can be referred to the international metrological reference, i.e. they are SI-traceable. The ICAG2009 was complemented by a number of associated measurements: the Relative Gravity Campaign (RGC2009), high-precision levelling and an accurate gravity survey in support of the BIPM watt balance project. The major measurements took place at the BIPM between July and October 2009. Altogether 24 institutes with 22 absolute gravimeters (one of the 22 AGs was ultimately withdrawn) and nine relative gravimeters participated in the ICAG/RGC campaign. This paper is focused on the absolute gravity campaign. We review the history of the ICAGs and present the organization, data processing and the final results of the ICAG2009. After almost thirty years of hosting eight successive ICAGs, the CIPM decided to transfer the responsibility for piloting the future ICAGs to NMIs, although maintaining a supervisory role through its Consultative Committee for Mass and Related Quantities. © 2012 BIPM & IOP Publishing Ltd. DA - 2012/10/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b8dc6bed-fdd6-42c7-99db-80699c494cd6 ER - TY - JOUR TI - Humidity effects on calibrations of radiation therapy electrometers DO - 10.1118/1.3679011 AU - Downton, B. AU - Walker, S. T2 - Medical Physics SN - 0094-2405 VL - 39 IS - 2 SP - 984 EP - 987 KW - article KW - calibration KW - computer assisted radiotherapy KW - electric capacitance KW - equipment KW - equipment design KW - humidity KW - instrumentation KW - radiometry KW - reproducibility KW - sensitivity and specificity KW - standard KW - static electricity KW - Calibration KW - Electric Capacitance KW - Equipment Design KW - Equipment Failure Analysis KW - Humidity KW - Radiometry KW - Radiotherapy, Conformal KW - Reproducibility of Results KW - Sensitivity and Specificity KW - Static Electricity AB - Purpose: To eliminate variation in electrometer calibration results caused by high humidity and suboptimal connectors on the standard capacitors and to implement hardware that prevents overloading of the input stage of electrometers during calibration. Methods: A humidity-controlled cabinet was installed to provide a low-humidity environment for the standard capacitors. All of the coaxial BNC connections were replaced with Triax (TRB) connectors with the exception of the output from the voltage source. A three-stage RC filter with cascaded RC low-pass sections was designed and tested. Results: The installation of the humidity cabinet resulted in a major improvement in the stability and reproducibility of the electrometer calibration system. For the three years since this upgrade, the Ionizing Radiation Standards (IRS) electrometer calibration results have been consistent regardless of the ambient relative humidity in the lab. The connector replacements improved grounding in the calibration circuit. The three-stage filter allows the voltage at the output to rise in an S-shaped waveform, resulting in a smooth rise of the current through the isolation resistor from zero and back again, with no abrupt transition. For the filter design chosen, 99.99 of the charge is delivered within 6 s. Conclusions: A three-way improvement to the calibration measurement system was successful in eliminating the observed variations, resulting in an electrometer calibration measurement system that is unaffected by humidity and allowing reliable year-round calibrations of any electrometer encountered since the implementation of these changes. DA - 2012/02/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d0d0e33b-1359-49ad-adce-546d3483a04b ER - TY - JOUR TI - Comment on "linearization of dose-response curve of the radiochromic film dosimetry system" [Med. Phys. 39 (8), 4850-4857 (2012)] DO - 10.1118/1.4762820 AU - Bouchard, Hugo AU - McEwen, Malcolm T2 - Medical Physics SN - 0094-2405 VL - 39 IS - 11 SP - 7171 EP - 7172 KW - film dosimeter KW - human KW - letter KW - methodology KW - standard KW - Film Dosimetry KW - Humans DA - 2012/11/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7fad606b-031f-4f8f-bacd-263feda559b0 ER - TY - JOUR TI - Improved Arabic-to-English statistical machine translation by reordering post-verbal subjects for word alignment DO - 10.1007/s10590-011-9112-y AU - Carpuat, Marine AU - Marton, Yuval AU - Habash, Nizar T2 - Machine Translation SN - 0922-6567 SN - 1573-0573 VL - 26 IS - 1-2 SP - 105 EP - 120 KW - Statistical machine translation; Reordering; VS; Post-verbal subjects; Matrix subject; Subject detection; Word alignment; Dependency parsing AB - We study challenges raised by the order of Arabic verbs and their subjects in statistical machine translation (SMT). We show that the boundaries of post-verbal subjects (VS) are hard to detect accurately, even with a state-of-the-art Arabic dependency parser. In addition, VS constructions have highly ambiguous reordering patterns when translated to English, and these patterns are very different for matrix (main clause) VS and non-matrix (subordinate clause) VS. Based on this analysis, we propose a novel method for leveraging VS information in SMT: we reorder VS constructions into pre-verbal (SV) order for word alignment. Unlike previous approaches to source-side reordering, phrase extraction and decoding are performed using the original Arabic word order. This strategy significantly improves BLEU and TER scores, even on a strong large-scale baseline. Limiting reordering to matrix VS yields further improvements. DA - 2012/03/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b822c6ac-5874-4beb-bb1f-501d403bb714 ER - TY - JOUR TI - An automatic network-extraction algorithm applied to magnetic survey data for the identification and extraction of geologic lineaments DO - 10.1190/1.3679324 AU - Lee, Madeline AU - Morris, William AU - Harris, Jeff AU - Leblanc, George T2 - Leading Edge (Tulsa, OK) SN - 1070-485X VL - 31 IS - 1 SP - 26 EP - 31 KW - Amplitude thresholding KW - Energy exploration KW - Geologic mapping KW - Geologic structures KW - Geophysical data KW - Geoscientific data KW - Lineament analysis KW - Local surfaces KW - Magnetic anomalies KW - Magnetic data KW - Magnetic surfaces KW - Magnetic surveys KW - Polylines KW - Quadratic surfaces KW - Ridge analysis KW - Synthetic datasets KW - Data processing KW - Geographic information systems KW - Geological surveys KW - Lithology KW - Magnetic polarity KW - Reliability analysis AB - Lineament analysis is commonly undertaken by interpreting a wide range of geoscientific data to delineate geologic structures. These structures include faults, fractures, dykes, and lithological contacts, which provide information for geologic mapping and mineral and energy exploration. We offer a simple automatic lineament analysis method that combines the principles of peak-identification algorithms typically used in geophysical data interpretation and a GIS drainage "network-extraction" algorithm commonly applied to a topographic surface. We apply this network-extraction process to a magnetic surface (grid) rather than a topographic one. The GIS approach calculates the curvature of a surface to determine whether a specific coordinate is at a minimum (trough). A simple quadratic surface is computed for a moving 3 × 3 window to determine if the local surface has the form of a dipping plane (or a trough). Continuity of troughs between adjacent kernels defines lineaments that typically correspond to streamflow pathways when analysis is carried out on a topographic surface. On a magnetic anomaly map surface, network extraction identifies magnetic lows that may represent faults that have undergone magnetite (depletion) alteration, or dykes with predominantly reversed polarity remanence. As network extraction is designed to locate troughs, it is possible to isolate normally magnetized dykes by inverting the values of a magnetic data set by to produce ridges. This modified ridge analysis method is successfully applied to three synthetic data sets, showing that network extraction offers the principal benefits of continuity in solutions to produce polylines (over isolated ridge solutions), automation for consistency and reliability, and optional amplitude thresholding. © 2012 Society of Exploration Geophysicists. DA - 2012/01/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : df1de529-6cd3-4872-839c-6637fe668190 ER - TY - JOUR TI - Improvement of color information in the generation of 3D models of real objects using range intensity images DO - 10.4028/www.scientific.net/KEM.523-524.362 AU - Takahama, Toru AU - Inomata, Ryo AU - Terabayashi, Kenji AU - Umeda, Kazunori AU - Godin, Guy T2 - Key Engineering Materials T3 - 14th International Conference on Precision Engineering, ICPE 2012, November 8-10, 2012, Hyogo SN - 1013-9826 SN - 9783037855096 VL - 523-524 SP - 362 EP - 367 KW - 3D models; colour image; rage intensity image; texture mapping AB - Texture mapping on scanned objects, which is the method to map color images on a 3D geometric model measured by a range image sensor, is often used for constructing a realistic 3D model. Color images are affected by the illumination conditions. Therefore, discontinuities of seams occur when simply applying texture mapping. In this paper, we propose a method for correcting the discontinuities using a range intensity image. A range intensity image is a kind of intensity image that is related to the reflectance ratio of the measured points, simultaneously acquired with a range image using an active range sensor. The method estimates the color information that is not affected by the lighting environment using multiple color images and a range intensity image. As a result, the method is effective to construct a 3D model with seamless color images. The effectiveness of the correction method is illustrated by experiments with real-world objects. DA - 2012/11/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : df5ebc09-feb0-491a-ac9f-2ebcf9272317 ER - TY - JOUR TI - A robust optimization approach for real-time multiple source drinking water blending problem DO - 10.2166/aqua.2012.037 AU - Peng, Wei AU - Mayorga, Rene V. AU - Imran, Syed T2 - Journal of Water Supply: Research and Technology - AQUA SN - 0003-7214 VL - 61 IS - 2 SP - 111 EP - 122 KW - fuzzy optimization; multi-objective; real-time operation; robust optimum; water quality AB - Although many optimization methods can be applied to real-time multiple source drinking water blending problems, the field still lacks an approach to rapidly produce a robust optimal solution by simultaneously optimizing multiple objectives. This paper develops a fuzzy multiple response surface methodology (FMRSM) to achieve this objective. In the FMRSM, experimental data are fitted to mean response surface models while the residuals (the error between the predicted response of the mean model and the measured data of the real system) are fitted to standard deviation models. Fuzzy linear programming using the min-operator approach is applied to optimize the multiple objectives. Six scenarios are designed based on data from a real-time multiple source drinking water blending operation. The results show the FMRSM is a robust, computationally efficient optimization approach. The FMRSM could be extended to other real-time multi-objective non-linear optimization problems. © IWA Publishing 2012. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e5d752ac-73c9-45a6-b096-2fd1be3f68d9 ER - TY - JOUR TI - Electrochemical testing of ultraporous membranes as separators in mild aqueous supercapacitors DO - 10.1149/2.020207jes AU - Laforgue, Alexis AU - Robitaille, Lucie T2 - Journal of the Electrochemical Society T3 - Meeting of The Electrochemical Society, May 1–6, 2011, Montreal, QC, Canada SN - 0013-4651 VL - 159 IS - 7 SP - A929 EP - A936 KW - Better performance KW - Electrochemical techniques KW - Electrochemical testing KW - Equivalent series resistance KW - Frequency ranges KW - Medium-frequency range KW - Super capacitor KW - Synergetic effect KW - Capacitors KW - Electric resistance KW - Pore size KW - Separators AB - Several commercially available separators as well as novel ultraporous electrospun nonwovens were evaluated in mild aqueous supercapacitor cells, using conventional electrochemical techniques. A special laboratory test-cell was designed and fabricated to accurately control the pressure applied to the stack. It was shown that the separator layer not only affects the equivalent series resistance (ESR) of the cell (high frequency range) but has also an influence on its time constant (medium frequency range). Both ESR and time constant were found to be directly proportional to the separator thickness. Higher porosity and higher pore size were found to lead to better performance, especially at higher power demand. The electrospun separators outperformed the other separator structures in a disruptive manner, most probably due to a synergetic effect of higher porosity and higher pore size. © 2012 The Electrochemical Society. DA - 2012/07/17 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 13efdd8f-86d2-4edc-87f5-4eeb0e7e6d66 ER - TY - JOUR TI - Volume stability of calcium sulfoaluminate phases DO - 10.1111/jace.12040 AU - Khoshnazar, Rahil AU - Beaudoin, James J. AU - Alizadeh, Rouhollah AU - Raki, Laila T2 - Journal of the American Ceramic Society SN - 0002-7820 VL - 95 IS - 12 SP - 3979 EP - 3984 KW - Constituent ions KW - Crystalline structure KW - Distilled water KW - Ettringites KW - Saturated water KW - Sulfoaluminate KW - Volume stability KW - Gypsum KW - Leaching KW - X ray diffraction analysis KW - Lime AB - The volume stability of calcium sulfoaluminate phases exposed to water, lime, and gypsum environments was investigated. The length changes of compacted specimens of synthetic monosulfate and ettringite were monitored in distilled water, lime-saturated water, gypsum-saturated water, and saturated water vapor. The X-ray diffraction analysis was also performed on the samples to assess the changes in the crystalline structure of each phase. Evidence was provided in support of the significant role of dissolution of monosulfate and ettringite, and the leaching of their constituent ions, on the expansion of these phases. © 2012 The American Ceramic Society. DA - 2012/10/26 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1a35921b-63a2-4519-8434-dc094e8e5690 ER - TY - JOUR TI - Rim-rotor rotary ramjet engine, part 1: structural design and experimental validation DO - 10.2514/1.B34227 AU - Rancourt, David AU - Picard, Mathieu AU - Denninger, Marc AU - Plante, Jean-Sébastien AU - Chen, Jihua AU - Yousefpour, Ali T2 - Journal of Propulsion and Power SN - 0748-4658 VL - 28 IS - 6 SP - 1293 EP - 1303 KW - Experimental validations KW - Flame holder KW - G-loads KW - High-temperature combustion KW - Partial failure KW - Power densities KW - Proof of concept KW - Rotor-dynamics KW - Short periods KW - Stationary power systems KW - Turbine blade KW - Ethers KW - Structural design KW - Ignition AB - The rim-rotor rotary-ramjet engine (R4E) is a new propulsion-system design with the potential to significantly improve power density and reduce complexity of conventional gas turbines, thus making it an interesting alternative for future transportation and stationary power systems. This paper presents the structural design and an experiment validation of a proof-of-concept prototype that can sustain 560 m=s (200 krpm) and transient combustion, which is initiated by an integrated-ignition system.Ahigh-strength carbon-polyetheretherketone (PEEK) composite winding is used around the ramjet blades to support the high g load and includes the flame holder. A6.5-cm prototype is spun up to 188 krpm at rim temperature, reaching 473-K for short periods without failure or rotordynamics issues. Several ignitions and high-temperature combustion of 1 s were achieved at 80,000 rpm. High-combustion temperature for 1 s led to the failure of turbine blades. Total and partial failures of the rim rotor demonstrated the concept safety, as all projections were contained without important damage. Copyright © 2012 by the authors. Published by the American Institute of Aeronautics and Astronautics, Inc. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cce58c9e-0ded-4ca9-b630-286ef9dd6cb0 ER - TY - JOUR TI - Data intensive high energy physics analysis in a distributed cloud DO - 10.1088/1742-6596/341/1/012003 AU - Charbonneau, A. AU - Agarwal, A. AU - Anderson, M. AU - Armstrong, P. AU - Fransham, K. AU - Gable, I. AU - Harris, D. AU - Impey, R. AU - Leavett-Brown, C. AU - Paterson, M. AU - Podaima, W. AU - Sobie, R.J. AU - Vliet, M. T2 - Journal of Physics: Conference Series T3 - 25th High Performance Computing Symposium 2011, HPCS 2011, June 15-17 2011, Montreal, Quebec, Canada SN - 1742-6588 VL - 341 IS - 1 SP - 12003 KW - Batch jobs KW - Calibration data KW - Cloud systems KW - Data intensive KW - High-throughput computing KW - Input datas KW - Running applications KW - System use KW - Virtual machines KW - Physics KW - High energy physics AB - We show that distributed Infrastructure-as-a-Service (IaaS) compute clouds can be effectively used for the analysis of high energy physics data. We have designed a distributed cloud system that works with any application using large input data sets requiring a high throughput computing environment. The system uses IaaS-enabled science and commercial clusters in Canada and the United States. We describe the process in which a user prepares an analysis virtual machine (VM) and submits batch jobs to a central scheduler. The system boots the user-specific VM on one of the IaaS clouds, runs the jobs and returns the output to the user. The user application accesses a central database for calibration data during the execution of the application. Similarly, the data is located in a central location and streamed by the running application. The system can easily run one hundred simultaneous jobs in an efficient manner and should scale to many hundreds and possibly thousands of user jobs. © IOP Publishing Ltd. DA - 2012/02/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 62199ecd-5f15-4f2d-a459-42212e41bc9e ER - TY - JOUR TI - Measuring the switching current of a superconducting single electron transistor in a tunable dissipative environment DO - 10.1088/1742-6596/400/4/042046 AU - Meng, S. AU - Yaraskavitch, L. AU - Sachrajda, A. S. AU - Kycia, J. B. T2 - Journal of Physics: Conference Series T3 - 26th International Conference on Low Temperature Physics (LT26), August 10-17 2011, Beijing, China SN - 1742-6588 VL - 400 IS - 4 SP - 42046 KW - Charging energies KW - Induced charges KW - Josephson coupling energies KW - Low temperatures KW - Periodic function KW - Quantum fluctuation KW - Superconducting single-electron transistors KW - Switching currents KW - Low temperature effects KW - Low temperature engineering KW - Quantum electronics KW - Superconductivity KW - Single electron transistors AB - We experimentally investigated the switching current Isw of a superconducting single electron transistor (sSET), with competitive Josephson coupling energy EJ and charging energy Ec, in an in situ tunable dissipative environment. At low temperature, averaged Isw shows a clear 1e periodic function of gate induced charge on the island. The relative contrast of this oscillation increases when EJ/Ec is lowered. Increasing dissipation reduce the quantum fluctuations of the phase across the sSET, leading to an increased Isw. © Published under licence by IOP Publishing Ltd. DA - 2012/12/17 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 56e38daf-f599-4fbb-9574-c499cb631e62 ER - TY - JOUR TI - Attosecond control of electron correlations in one-photon ionization and recombination DO - 10.1088/0953-4075/45/13/131002 AU - Patchkovskii, Serguei AU - Smirnova, Olga AU - Spanner, Michael T2 - Journal of Physics B: Atomic, Molecular and Optical Physics SN - 0953-4075 VL - 45 IS - 13 SP - 131002 KW - Attoseconds KW - Control phase KW - Cross section KW - Final state KW - Giant resonances KW - Infrared field KW - Interfering pathways KW - Ionic channels KW - Multielectron system KW - Radiative recombination KW - Relative phasis KW - Strong laser field KW - Photoionization AB - Electron-electron interactions in multielectron systems may cause multiple ionic channels to contribute to amplitudes of ionization or radiative recombination, giving rise to interfering pathways to the same final state. These channels are not individually observable in standard weak-field experiments, where they all contribute to the same final-state resolved cross section. We show how one can use strong laser fields to control the timing of electronelectron interactions. We demonstrate that the relative phases of the direct and correlation channels can be manipulated by a strong infrared field, permitting experimental separation of the individual contributions. The control phase can be calibrated using the attosecond streak camera. The required control conditions are achieved at the rising edge of the giant resonance in the Xe atom. DA - 2012/06/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fda8cfce-27ba-43af-988a-7f883a05c5ae ER - TY - JOUR TI - Molecular-frame photoelectron angular distributions DO - 10.1088/0953-4075/45/19/190201 AU - Lucchese, Robert R. AU - Stolow, Albert T2 - Journal of Physics B: Atomic, Molecular and Optical Physics SN - 0953-4075 VL - 45 IS - 19 SP - 190201 DA - 2012/09/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c132ca84-7fa8-4a97-8387-47860ca89d81 ER - TY - JOUR TI - Preconditioning induces tolerance by suppressing glutamate release in neuron culture ischemia models DO - 10.1111/j.1471-4159.2012.07791.x AU - Tauskela, Joseph S. AU - Aylsworth, Amy AU - Hewitt, Melissa AU - Brunette, Eric AU - Mealing, Geoffrey A. R. T2 - Journal of Neurochemistry SN - 0022-3042 VL - 122 IS - 2 SP - 470 EP - 481 KW - excitotoxicity; glutamate; neuroprotection; preconditioning; synaptic scaling; tolerance AB - This study determined how preconditioned neurons responded to oxygen-glucose deprivation (OGD) to result in neuroprotection instead of neurotoxicity. Neurons preconditioned using chronically elevated synaptic activity displayed suppressed elevations in extracellular glutamate ([glutamateex]) and intracellular Ca²+ (Ca²+ in) during OGD. The glutamate uptake inhibitor TBOA induced neurotoxicity, but at a longer OGD duration for preconditioned cultures, suggestive of delayed up-regulation of transporter activity relative to non-preconditioned cultures. This delay was attributed to a critically attenuated release of glutamate, based on tolerance observed against insults mimicking key neurotoxic signaling during OGD (OGD-mimetics). Specifically, in the presence of TBOA, preconditioned neurons displayed potent protection to the OGD-mimetics: ouabain (a Na+/K+ ATPase inhibitor), high 55 mM KCl extracellular buffer (plasma membrane depolarization), veratridine (a Na+ ionophore), and paraquat (intracellular superoxide producer), which correlated with suppressed [glutamateex] elevations in the former two insults. Tolerance by preconditioning was reversed by manipulations that increased [glutamateex], such as by exposure to TBOA or GABAA receptor agonists during OGD, or by exposure to exogenous NMDA or glutamate. Pre-synaptic suppression of neuronal glutamate release by preconditioning, possibly via suppressed exocytic release, represents a key convergence point in neuroprotection during exposure to OGD and OGD-mimetics. © 2012 National Research Council Canada. Journal of Neurochemistry © 2012 International Society for Neurochemistry. DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0c2b3dd1-3d70-4c7f-9ae7-77b5f8958b09 ER - TY - JOUR TI - Development of an analytical microbial consortia method for enhancing performance monitoring at aerobic wastewater treatment plants DO - 10.1080/10934529.2012.664996 AU - Razban, Behrooz AU - Nelson, Kristina Y. AU - McMartin, Dena W. AU - Cullimore, D. Roy AU - Wall, Michelle AU - Wang, Dunling T2 - Journal of Environmental Science and Health - Part A Toxic/Hazardous Substances and Environmental Engineering SN - 1093-4529 VL - 47 IS - 6 SP - 830 EP - 836 KW - FAME, microbial consortia, process monitoring, aerobic wastewater treatment AB - An analytical method to produce profiles of bacterial biomass fatty acid methyl esters (FAME) was developed employing rapid agitation followed by static incubation (RASI) using selective media of wastewater microbial communities. The results were compiled to produce a unique library for comparison and performance analysis at a Wastewater Treatment Plant (WWTP). A total of 146 samples from the aerated WWTP, comprising 73 samples of each secondary and tertiary effluent, were included analyzed. For comparison purposes, all samples were evaluated via a similarity index (SI) with secondary effluents producing an SI of 0.88 with 2.7% variation and tertiary samples producing an SI 0.86 with 5.0% variation. The results also highlighted significant differences between the fatty acid profiles of the tertiary and secondary effluents indicating considerable shifts in the bacterial community profile between these treatment phases. The WWTP performance results using this method were highly replicable and reproducible indicating that the protocol has potential as a performance-monitoring tool for aerated WWTPs. The results quickly and accurately reflect shifts in dominant bacterial communities that result when processes operations and performance change. © 2012 Copyright Taylor and Francis Group, LLC. DA - 2012/03/16 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 25e1a00f-962c-4cd7-9f8e-4cf9d7be975b ER - TY - JOUR TI - Automatically creating design models from 3D anthropometry data DO - 10.1115/1.4007839 AU - Wuhrer, Stefanie AU - Shu, Chang AU - Bose, Prosenjit T2 - Journal of Computing and Information Science in Engineering SN - 1530-9827 VL - 12 IS - 4 SP - 41007 KW - 3D anthropometry KW - 3D models KW - Covering problems KW - Design applications KW - Design models KW - Digital forms KW - Manual interaction KW - Parameter spaces KW - Anthropometry KW - Computational geometry KW - Product design KW - Three dimensional computer graphics AB - When designing a product that needs to fit the human shape, designers often use a small set of 3D models, called design models, either in physical or digital form, as representative shapes to cover the shape variabilities of the population for which the products are designed. Until recently, the process of creating these models has been an art involving manual interaction and empirical guesswork. The availability of the 3D anthropometric databases provides an opportunity to create design models optimally. In this paper, we propose a novel way to use 3D anthropometric databases to generate design models that represent a given population for design applications such as the sizing of garments and gear. We generate the representative shapes by solving a covering problem in a parameter space. Well-known techniques in computational geometry are used to solve this problem. We demonstrate the method using examples in designing glasses and helmets. © 2012 American Society of Mechanical Engineers. DA - 2012/11/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4031b6a2-07db-41ac-b9f6-e9bb3c3e2ea4 ER - TY - JOUR TI - Similitude study on bending stiffness and behavior of composite tubes DO - 10.1177/0021998311431642 AU - Derisi, Bijan AU - Hoa, Suong AU - Hojjati, Mehdi T2 - Journal of Composite Materials SN - 0021-9983 VL - 46 IS - 21 SP - 2695 EP - 2710 KW - composite tube; flexural stiffness; large deformation; thermoplastics; progressive failure AB - A procedure to design a composite tube that matches the flexural stiffness, load-carrying capacity, and energy absorption of an aluminum tube while subjected to bending load is of interest. The large deformation and energy absorption requirements are fulfilled through the progressive failure of the plies of suitable fiber orientations across the thickness of the tube. The layer wise nature of the composite tubes and cylindrical anisotropy, however, has impeded obtaining a simple closed-form solution for calculating the flexural stiffness. Available analytical solutions are mainly a complex set of equations, which should be solved simultaneously. In addition, the boundary and interface conditions between the adjacent plies must be satisfied. This article presents a straightforward simulation technique for this purpose. First, the tube is correlated to a corresponding composite sandwich panel, the flexural stiffness of which is obtained by the classical laminate theory. Then an analogous aluminum sandwich panel is designed and is correlated to a so-called 'equivalent' aluminum tube. The bending stiffness of the composite tube is shown to be the same as that of its equivalent aluminum tube. As a result, a complex problem of cylindrical anisotropy is mapped into a Cartesian coordinate system and solved via the classical laminate theory. The accuracy of the technique is verified by experimental work and analytical solutions. The agreement between the three methods is shown. © 2011 The Author(s). DA - 2012/07/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c822dad7-2d63-45f4-ab59-d26afe24cc0a ER - TY - JOUR TI - Series-coupled triple quantum dot molecules DO - 10.1143/JJAP.51.02BJ06 AU - Amaha, Shinichi AU - Hatano, Tsuyoshi AU - Izumida, Wataru AU - Teraoka, Soichiro AU - Ono, Keiji AU - Kono, Kimitoshi AU - Tarucha, Seigo AU - Aers, Geof AU - Gupta, James AU - Austing, Guy T2 - Japanese Journal of Applied Physics SN - 0021-4922 VL - 51 IS - 2 SP - 02BJ06 KW - Coulomb diamonds KW - Design Principles KW - Device processing KW - Double-quantum dot device KW - Interaction model KW - Random impurities KW - Region shape KW - Sequential tunneling KW - Single gates KW - Submicron KW - Triple quantum KW - Well structure KW - Well thickness KW - Coulomb blockade KW - Electronic properties KW - Semiconductor device structures KW - Semiconductor quantum dots AB - We present the electronic properties of a triple quantum dot molecule embedded inside a sub-micron mesa, made from a quadruple-barrier triplequantum- well structure, and surrounded by a single gate electrode. We outline the design principles of the quadruple-barrier triple-quantum-well structure and calculate the energy of the three lowest states as a function of center well thickness. We observe regular and irregular shaped Coulomb diamond regions similar to those for double quantum dot devices. Variation in the Coulomb blockade region shape is introduced by fluctuation in the offset energies between the quantum dots likely associated with device processing and random impurity potential in the material. We also present Coulomb blockade patterns calculated with a constant interaction model for sequential tunneling through the three series-coupled quantum dots. © 2012 The Japan Society of Applied Physics. DA - 2012/02/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2356459a-c035-423d-a4dd-7433e49f2f22 ER - TY - JOUR TI - Impact behavior of thin thermoplastic composites dependant on manufacturing parameters and layup AU - Wedekind, Max AU - Khoun, Loleï AU - Krempl, Peter AU - Baier, Horst AU - Hubert, Pascal T2 - International SAMPE Technical Conference T3 - 2012 SAMPE International Symposium and Exhibition - Emerging Opportunities: Materials and Process Solutions, 21 May 2012 through 24 May 2012, Baltimore, MD SN - 9781934551127 KW - Carbon composite plates KW - Carbon composites KW - Compression after impact tests KW - Damage size KW - High stiffness KW - Impact behavior KW - Impact damages KW - Impact performance KW - In-plane stiffness KW - Laminate configuration KW - Lightweight application KW - Manufacturing parameters KW - Manufacturing process KW - Material property KW - Premature failures KW - Residual strength KW - Resin systems KW - Specific strength KW - Stacking sequence KW - Structural applications KW - Thermoplastic composite KW - Thermoset resin KW - Thin plate KW - Buckling KW - Composite materials KW - Equipment testing KW - Exhibitions KW - Laminates KW - Manufacture KW - Plates (structural components) KW - Resins KW - Thermosets KW - Stiffness AB - The amount of structural application of carbon composites has grown massively in the last years. Carbon composites are known to provide superior performance with regard to their specific strength and stiffness. One of the major drawbacks, limiting the fields of application and defining knock down factors, is their sensitivity for impact damages. Thermoplastic resin systems are known to provide a better performance on impact behavior compared to thermoset resin systems. Within this paper, an investigation on the impact behavior of carbon composite plates with PEEK resin system is presented. The impact performance is derived by measurement of damage size, penetration depth and residual strength. For structural applications, composites provide the possibility to take use of tailored mechanical properties of laminates, like strength and stiffness by defining specific stacking sequences. Since the impact performance is also affected by the layup, different laminate configurations, starting from low in plane stiffness up to high stiffness, were investigated. Particularly for lightweight applications thin laminates are relevant. To provide the capability to determine the post impact compressive strength of thin plates, avoiding premature failure caused by buckling, a modified test bed for compression after impact test has been developed. Furthermore, within this work the influence of different manufacturing parameters on the impact performance and material properties was investigated, thus allowing an optimized manufacturing process with regard to cost and performance. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6216290c-68b1-40e0-a1da-5ee47b89e262 ER - TY - JOUR TI - Enhanced fire resistance of cellulosic fibers for green polymer composites AU - Ngo, Tri-Dung AU - Ton-That, Minh-Tan AU - Hu, Wei T2 - International SAMPE Technical Conference T3 - SAMPE Tech 2012 Conference and Exhibition: Navigating the Global Landscape for the New Composites, October 22-25, 2012, North Charleston, SC, USA SN - 9781934551134 KW - Cellulosic fibers KW - Cellulose fibers KW - Different treatments KW - Fiber strength KW - Green polymers KW - Polymer composite KW - Renewable resource KW - Sustainable treatments KW - Composite materials KW - Composites KW - Environmental impact KW - Fire resistance KW - Thermal resistance KW - Inorganic chemicals KW - Mechanical properties AB - The incorporation of renewable resources in composite materials is a viable means to reduce environmental impact and support sustainability development in the composites industry. Cellulosic fiber polymer composites have received very much attraction for different industrial applications because of its low density and the renewable ability. However, the uses of cellulosic fibers in the composite are limited in many applications that require fire resistance due to their flammability and their low thermal resistance. This paper reports an innovative and sustainable treatment approaches to retard the burning of cellulosic fibers for composite production in which a minimum amount of non-toxic and low cost inorganic chemicals have been used. Different types of reacting minerals and different treatment parameters have been investigated in order to determine the most cost-effective treatment solution. The cellulosic fibers obtained from this approach become self-extinguished while there is no negative effect on fiber strength. The composite with the treated cellulosic fibers also shows their good fire resistance with minor effect on the mechanical properties. Thus this solution will open the door for the use of the cellulosic fibers in composites for applications where fire resistance is an important issue, particularly in aerospace, transportation, and construction. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f18545ea-dc25-4b7d-b01c-a0fd2c5f1402 ER - TY - JOUR TI - Field study assessment of the performance of displacement air distribution in a canadian school during the heating season AU - Ouazia, Boualem AU - Macdonald, Iain AU - Tardif, Michel AU - Thompson, Alexandra AU - Booth, Daniel T2 - International Journal of Ventilation SN - 1473-3315 VL - 11 IS - 1 SP - 43 EP - 51 KW - stratified ventilation KW - Contaminant removal KW - Displacement ventilation system KW - IAQ KW - Pollutant distribution KW - Carbon dioxide KW - Hot water heating KW - Thermal comfort AB - Stratified ventilation systems use a fundamentally different approach to supply heated or cooled air through a building than the 'fully mixed and dilution' ventilation systems found in the majority of non-residential buildings. Stratified air distribution creates a non-uniform environment in terms of temperature and pollutant distribution, and acceptable conditions in the occupied zone. Previous research has shown that this type of system works well for regions where buildings require year-round cooling. However there are a growing number of buildings using this approach in Canada, where buildings require heating during winter months. This paper presents results from a field study conducted in a school equipped with a displacement ventilation system. The results show that the measured contaminant removal efficiency (based on CO 2 measurements) resulting from displacement ventilation in this case is better than that was predicted in previous studies for displacement ventilation under heating operation. In addition, key predictors of thermal comfort (the measured vertical air temperature difference and draft rating at ankle and head height) are also generally within the limits set by applicable ASHRAE standards. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : dd88c2fc-06c4-4774-83dd-da30e130b7c8 ER - TY - JOUR TI - Encounters with vortices in a turbine nozzle passage DO - 10.1155/2012/928623 AU - Gostelow, J. P. AU - Mahallati, A. AU - Carscallen, W. E. AU - Rona, A. T2 - International Journal of Rotating Machinery SN - 1023-621X VL - 2012 SP - 928623 KW - Base pressure KW - Blade wake KW - Blunt leading edges KW - Convex curvatures KW - Convex surfaces KW - Energy separations KW - Flowthrough KW - Horseshoe vortices KW - Linear cascade KW - Passage vortex KW - Separation regions KW - Shedding modes KW - Streamwise vortices KW - Subsonic speed KW - Suction surfaces KW - Surface flow visualization KW - Time resolved measurement KW - Transonic speed KW - Transonic turbine cascade KW - Turbine nozzles KW - Flow visualization KW - Secondary flow KW - Turbine components KW - Vorticity KW - Wakes KW - Vortex flow AB - Experiments were conducted on the flow through a transonic turbine cascade. Secondary flows and a wide range of vortex types were encountered, including horseshoe vortices, shock-induced passage vortices, and streamwise vortices on the suction surface. In the separation region on the suction surface, a large rollup of passage vorticity occurred. The blunt leading edge gave rise to strong horseshoe vortices and secondary flows. The suction surface had a strong convex curvature over the forward portion and was quite flat further downstream. Surface flow visualization was performed and this convex surface displayed coherent streamwise vorticity. At subsonic speeds, strong von Kármán vortex shedding resulted in a substantial base pressure deficit. For these conditions, time-resolved measurements were made of the Eckert-Weise energy separation in the blade wake. At transonic speeds, exotic shedding modes were observed. These phenomena all occurred in experiments on the flow around one particular turbine nozzle vane in a linear cascade. © 2012 J. P. Gostelow et al. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6675d045-4f49-4e93-a0f2-8270bfd8b294 ER - TY - JOUR TI - Characterization of the formation of nickel-rich areas in PM steels and their effect on mechanical properties AU - Tougas, B. AU - Blais, C. AU - Larouche, M. AU - Chagnon, F. AU - Pelletier, S. T2 - International Journal of Powder Metallurgy SN - 0888-7462 VL - 48 IS - 6 SP - 7 EP - 18 AB - Admixed chemical elements may lead to the formation of heterogeneous microstruc-tures in sintered steels. This is due primarily to low bulk-diffusion coefficients at conventional sintering tem peratures. For powder met allurgy (PM) steels, admixed nickel is well known to produce such heterogeneous microstructures where the element is not distributed evenly upon sintering, resulting in the formation of nickel-rich areas (NRAsj. In contrast, the principal mechanisms of nickel diffusion in PM steels are often misunderstood. This work presents a new approach to measure the bulk-diffusion coefficients of nickel in PM steels in order to determine the sintering conditions required to maximize its homogeneity in a steel matrix. Also, the influence of the local concentration of nickel on sintered microstructures is discussed. The characterization approach presented here could be used to characterize the diffusion of other alloying elements in PM steels, either admixed as elemental powders or introduced via master alloys. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9a9e5a69-d042-47b4-b881-5041f1100a00 ER - TY - JOUR TI - Functionalised silica nanoparticles stable in serum-containing medium efficiently deliver siRNA targeting HIV-1 co-receptor CXCR4 in mammalian cells DO - 10.1504/IJNBM.2012.051704 AU - Kell, Arnold J. AU - Barnes, Michael L. AU - Slater, Kathryn AU - Lavigne, Carole T2 - International Journal of Nano and Biomaterials SN - 1752-8933 VL - 4 IS - 3/4 SP - 223 EP - 242 KW - Cellular uptake KW - CXCR4 KW - Dye-doped silica nanoparticles KW - HIV-1 co-receptor KW - Serum-containing medium KW - siRNA delivery KW - Drug therapy KW - Genetic engineering KW - Nanoparticles KW - Nanostructured materials KW - chemokine receptor CXCR4 KW - messenger RNA KW - nanoparticle KW - nuclease KW - polyethyleneimine KW - silicon dioxide KW - small interfering RNA KW - tetramethylrhodamine doped silica nanoparticle KW - cell viability KW - cellular distribution KW - chemical binding KW - endosome KW - enzyme degradation KW - gene silencing KW - human cell KW - Human immunodeficiency virus 1 KW - lysosome KW - mammal cell KW - nonviral gene delivery system KW - protein expression KW - RNA binding KW - RNA degradation AB - The development of non-viral DNA delivery systems using nanomaterials has attracted much research interest for its potential in biomedicine. However, for these new nanocarriers to be successfully used in therapeutic applications they have to overcome many barriers. Here, we report the development and characterisation of polyethyleneimine-modified tetramethylrhodamine-doped silica nanoparticles as a vehicle to deliver siRNA in the presence of serum. We have demonstrated that polyethyleneiminemodified tetramethylrhodamine-doped silica nanoparticles bind and protect siRNA against nuclease degradation and facilitate cellular uptake and intracellular delivery of the siRNA in HeLa-derived TZM-bl cells. The nanoparticles can penetrate TMZ-bl cells at concentrations as low as 1 μg/mL and can escape the lysosomal and endosomal cavities. Following delivery, the nanoparticles release active siRNA targeting the co-receptor CXCR4 for HIV-1 to achieve reduction in the targeted mRNA and protein expression. These nanoparticles are also non-toxic for the cells and are capable of carrying out all of these functions in the presence of serum, a characteristic that is critical if such nanoparticles are to be employed in any type of in vivo application. Copyright © 2012 Inderscience Enterprises Ltd. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4e9c3ab9-02ce-4980-b6bf-5f13d7a3ad09 ER - TY - JOUR TI - Mechanical properties of aluminium-copper B206 alloys with iron and silicon additions DO - 10.1179/1743133610Y.0000000012 AU - Kamga, H. K. AU - Larouche, D. AU - Bournane, M. AU - Rahem, A. T2 - International Journal of Cast Metals Research SN - 1364-0461 VL - 25 IS - 1 SP - 15 EP - 25 KW - B206 ; Intermetallics ; Ductility ; Macrosegregation ; Quality index AB - Mechanical properties of B206 aluminium alloys with additions of iron and silicon were studied to investigate the combined effect of these additions on tensile strengths and ductility. Properties are highly influenced by the iron to silicon ratio and the nominal concentration of the single elements. The best properties were obtained with both a ratio close to one and low concentrations of iron and silicon. Present experimental results show that it is possible to multiply by two or three the present limit of 0·1 wt-%Fe in these alloys at natural aging (T4) and still obtain the minimum of 7% elongation required by the automotive industry. At artificial aging (T7), it will be very difficult however to reach the 7% elongation with ~0·2 wt-%Fe and 0·2 wt-%Si, while this seems impossible with ~0·3 wt-%Fe and 0·3 wt-%Si. It was found that macrosegregation of Cu in the gage section of the ASTM B108 test bars is responsible for an enrichment of 0·8-0·9 wt-%of this element in the test zone. This has produced microstructures saturated in Cu with little Al 2Cu phase remaining after the solution heat treatment. Owing to the low amount of this phase and the round shape of the particles, the remaining Al 2Cu phase did not have a significant impact on the ductility. One benefit of working with a Cu saturated microstructure is that one can estimate the true temperature of the solution heat treatment by conducting a post-analysis of Cu content in the dendrites. This should be helpful to reduce the variability in properties and to improve the temperature distribution in heat treating furnaces. DA - 2012 PY - 2012 LA - eng N1 - A. Rahem was affiliated with the NRC Aluminium Technology Centre at time of publication. C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8e5c2c10-2afd-4202-a828-30081f6be732 ER - TY - JOUR TI - Diffractive and subwavelength grating couplers for microphotonic waveguides DO - 10.1109/ICTON.2012.6253914 AU - Cheben, P. AU - Schmid, J. H. AU - Ramos, C. A. AU - Halir, R. AU - Zavargo-Peche, L. AU - Lapointe, J. AU - Bock, P. AU - Xu, D.-X. AU - Janz, S. AU - Ortega-Monux, A. AU - Molina-Fernandez, I. AU - Ma, R. AU - Vachon, M. AU - Delage, A. AU - Fedeli, J.-M. T2 - ICTON 2012: 14th International Conference on Transparent Optical Networks T3 - 14th International Conference on Transparent Optical Networks, ICTON 2012, 2 July 2012 through 5 July 2012, Coventry SN - 978-1-4673-2228-7 SN - 9781467322270 SP - 6253914 KW - 3 dB bandwidth KW - Back reflection KW - Coupling efficiency KW - Effective medium KW - Excitation field KW - Fabrication tolerances KW - Fundamental modes KW - Grating couplers KW - Higher-order modes KW - I-line steppers KW - Microphotonic waveguides KW - Multimodes KW - Silicon rib waveguides KW - Single etch KW - Sub-wave length grating KW - Sub-wavelength KW - Surface grating KW - Wavelength dependence KW - Wavelength ranges KW - Fabrication KW - Refractive index KW - Ridge waveguides KW - Transparent optical networks KW - Waveguides AB - We review our advances in diffractive and subwavelength grating coupler structures for microphotonic waveguides. We present a subwavelength grating fiber-chip edge coupler with a loss as low as 0.9 dB and with minimal wavelength dependence over a broad wavelength range exceeding 200 nm. We also present fiber-to-chip surface grating couplers based on subwavelength effective medium. The effective medium refractive index is engineered to control the strength of the grating and thereby maximize coupling efficiency, while mitigating back reflections at the same time. We analyze the fabrication tolerances of the coupler, which are of particular relevance for large scale photonic fabrication. Furthermore, we present the first grating coupler for micrometric silicon rib waveguides, which is particularly challenging since the coupler waveguide region is multimode. We experimentally demonstrate grating couplers in 1.5 μm thick silicon ridge waveguides with a coupling efficiency of 2.2 dB and a 3 dB bandwidth of 40 nm. An inverse taper is used to match the fundamental mode of the interconnection waveguide with the optimum grating coupler excitation field, with negligible higher order mode excitation. The coupler was fabricated using i-line stepper lithography and single etch step. © 2012 IEEE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : dcac9ee1-cd62-4d26-a436-f810f4893ea1 ER - TY - JOUR TI - Methodology for determination of ice management efficiency AU - Vachon, Guy AU - Sayed, Mohamed AU - Kubat, Ivana T2 - International Conference and Exhibition on Performance of Ships and Structures in Ice 2012, ICETECH 2012 T3 - 10th International Conference and Exhibition on Performance of Ships and Structures in Ice 2012, ICETECH 2012, September 17-20, 2012, Banff, AB, Canada SN - 9781622768011 SP - 346 EP - 353 KW - Design and optimization KW - Floe sizes KW - Ice cover KW - Ice dynamics KW - Ice forces KW - Ice management KW - Exhibitions KW - Meteorological problems KW - Ships KW - Vehicle performance KW - Ice AB - The paper describes a methodology for evaluating the effectiveness of ice management (IM) operations, which is part of a larger effort aimed at developing efficient IM systems. Ice dynamics simulations are used to determine ice forces on an assumed structure. The simulations examine the role of variables that can be altered by IM operations such as floe size, ice confinement and ice pressure. The results provide means for quantifying the benefits from icebreaking operations, which is a needed input for the design and optimization of IM systems. Ongoing work employs related techniques to determine icebreaking requirements and IM efficiency. Copyright ©2012 ICETECH 12. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 07f40538-d249-422a-857a-acd91ba15d72 ER - TY - JOUR TI - Quantifying ice pressure conditions and predicting the risk of ship besetting AU - Kubat, Ivana AU - Babaei, M. Hossein AU - Sayed, Mohamed T2 - International Conference and Exhibition on Performance of Ships and Structures in Ice 2012, ICETECH 2012 T3 - 10th International Conference and Exhibition on Performance of Ships and Structures in Ice 2012, ICETECH 2012, September 17-20, 2012, Banff, AB, Canada SN - 9781622768011 SP - 106 EP - 113 KW - Besetting KW - Environmental forcing KW - Hindcasts KW - Ice dynamics KW - Normal stress KW - Parametric study KW - Pressure conditions KW - Significant variables KW - Exhibitions KW - Risk assessment KW - Ships KW - Vehicle performance KW - Ice AB - The risks of ship besetting under ice pressure are examined. Hindcasts of ice dynamics examine the conditions that led to the besetting of two vessels in the Gulf of St. Lawrence on 9 March 2005. The analysis examines the distributions of potentially significant variables such as pressure (mean normal stress), ridge thickness and strain rates. A criterion for assessing the risk of besetting was then proposed. A preliminary parametric study was also done in order to illustrate a method for predicting the risk of besetting under different ice and environmental forcing conditions. Copyright ©2012 ICETECH 12. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e272d171-ed20-4847-a7c7-c71bf6a26a53 ER - TY - JOUR TI - Numerical simulations of ice interaction with a moored structure AU - Sayed, Mohamed AU - Kubat, Ivana AU - Wright, Brian AU - Iyerusalimskiy, Aleksandr AU - Phadke, Amal AU - Hall, Brenda T2 - International Conference and Exhibition on Performance of Ships and Structures in Ice 2012, ICETECH 2012 T3 - 10th International Conference and Exhibition on Performance of Ships and Structures in Ice 2012, ICETECH 2012, September 17-20, 2012, Banff, AB, Canada SN - 9781622768011 SP - 159 EP - 166 KW - Floe sizes KW - Historical records KW - Ice accumulation KW - Ice forces KW - Ice interactions KW - Kulluk KW - Moored structures KW - Three dimensional simulations KW - Computer simulation KW - Exhibitions KW - Meteorological problems KW - Mooring KW - Numerical models KW - Ships KW - Vehicle performance KW - Ice AB - Numerical simulations are carried out to represent the historical data of ice interaction with the Kulluk during the 1980s. Three dimensional simulations include dynamics of the ice cover and the response of the mooring system. The results give modes of ice accumulation, clearing and ice forces. Depth-averaged simulations consider larger zones of the ice cover to examine a range of conditions that were observed during the past operation of the Kulluk in the Beaufort Sea. The simulations evaluate the effects of managed ice cover characteristics such as floe sizes and confinement. Predicted forces are compared to the historical record of measurements. Copyright © 2012 ICETECH 12. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e7bb4032-bfa4-48dd-b4f6-dafe11063d5c ER - TY - JOUR TI - Strength and pressure profiles from conical ice crushing experiments AU - Gudimetla, P. S. Reddy AU - Colbourne, Bruce AU - Daley, Claude AU - Bruneau, Stephen E. AU - Gagnon, Robert T2 - International Conference and Exhibition on Performance of Ships and Structures in Ice 2012, ICETECH 2012 T3 - 10th International Conference and Exhibition on Performance of Ships and Structures in Ice 2012, ICETECH 2012, September 17-20, 2012, Banff, AB, Canada SN - 9781622768011 SP - 167 EP - 174 KW - Experimental apparatus KW - Ice loads KW - Pressure area relationships AB - Experimental procedures for obtaining the crushing strength and pressure profiles of cone shaped ice samples are presented. These experiments were conducted as the part of the STePS2 (Sustainable Technology for Polar Ships and Structures) research project at Memorial University, St. John's, Canada. An objective of this project is to study the response of a full size structural grillage for both quasi-static and dynamic ice loading. To prepare for the structural tests, both 1/4 m dia. and 1m dia. conical ice samples are being crushed against a rigid high-resolution pressure panel in quasi-static conditions. Data from the tests on the pressure panel will help to set the conditions for the later quasi-static and dynamic experiments on the steel grillage. Contact pressure profiles are obtained at each time step during the experiments. The pressure profiles obtained reveal the shape and variability of the high pressure zones that develop during ice-structure contact. The paper describes the experimental procedure including; making the ice samples, shaping the samples, crushing tests and data analysis. Preliminary experimental data from both small cones (i.e., 25 cm diameter) and large cones (i.e., 1 m diameter) tests are provided in this paper. Copyright ©2012 ICETECH 12. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 87db5d3c-118e-4de2-ac95-dc3c9b126d49 ER - TY - JOUR TI - Wireless sensor network reliability and security in factory automation: a survey DO - 10.1109/TSMCC.2012.2205680 AU - Islam, Kamrul AU - Shen, Weiming AU - Wang, Xianbin T2 - IEEE Transactions on Systems, Man and Cybernetics Part C: Applications and Reviews SN - 1094-6977 VL - 42 IS - 6 SP - 6392470 SP - 1243 EP - 1256 KW - Cryptography KW - Factory automation KW - Reliability KW - Security KW - Wireless sensor networks (WSNs) AB - Industries can benefit a lot from integrating sensors in industrial plants, structures, machinery, shop floors, and other critical places and utilizing their sensing and monitoring power, communicating and processing abilities to deliver sensed information. Proper use of wireless sensor networks (WSNs) can lower the rate of catastrophic failures, and improve the efficiency and productivity of factory operations. Ensuring reliability and providing adequate security in these crucial services provided by WSNs will reinforce their acceptability as a viable and dependable technology in the factory and industrial domain. In this paper, we examine the reliability and security challenges of WSNs and survey their practicality for industrial adoption. We discuss the unique characteristics that distinguish the factory environment from the rest, elaborate on security and reliability issues with their respective solution measures, and analyze the existing WSN architectures and standards. A number of challenges and interesting research issues have emerged from this study and have been reported for further investigation. © 1998-2012 IEEE. DA - 2012/12/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 13a700fb-2487-477b-93b5-0086fccdbf59 ER - TY - JOUR TI - Evaluation of high density pixellated crystal blocks with SiPM readout as candidates for PET/MR detectors in a small animal PET insert DO - 10.1109/TNS.2012.2201958 AU - Thompson, C. J. AU - Goertzen, A. L. AU - Berg, E. J. AU - Retiere, F. AU - Kozlowski, P. AU - Ryner, L. AU - Stortz, G. AU - Sossi, V. T2 - IEEE Transactions on Nuclear Science SN - 0018-9499 VL - 59 IS - 5 SP - 6298061 SP - 1791 EP - 1797 KW - Bottom layers KW - Crystal block KW - Crystal density KW - Crystal response KW - Dual layer KW - Field of views KW - High density KW - High packing density KW - Low bias voltage KW - Lutetium oxyorthosilicate KW - PET scanner KW - Pixellated crystals KW - Pre-clinical KW - Response functions KW - Silicon photomultiplier KW - Small animal PET KW - Small animal PET scanners KW - Translation stage KW - Detectors KW - Photomultipliers KW - Polyethylene terephthalates KW - Positron emission tomography KW - Separation KW - Sodium KW - Silicon detectors AB - Arrays of silicon photo-multipliers (SiPMs) are good candidates for the readout of detectors in PET/MR inserts due to their high packing density, efficiency, low bias voltage and insensitivity to magnetic fields. We tested two dual-layer blocks of pixellated lutetium oxy-orthosilicate (LYSO) coupled to SensL 4× 4 SiPM arrays in terms of their ability to resolve all elements using resolvability index (RI) defined by the FWHM of the crystal response function divided by the separation. Our crystal blocks had 49 1.67×1.67×6.0 mm 3 crystals on the bottom layer and 36 1.67× 1.67× 4.0 mm 3 crystals in the top layer (offset by 1/2 of the crystal pitch). All 85 crystals were well resolved: RI= 0.46 compared with RI = 0.41 for a conventional pre-clinical PET scanner's block with 40% lower crystal density. A pair of crystal blocks mounted on translation stages scanned a 0.25 mm 22Na source in 60 0.25 mm steps with the detectors angulated as if there were 16 blocks in a ring. The FWHM of the coincidence response function near the centre of the field of view was 1.31 mm and FWTM was 2.7 mm with the detectors separated by 200 mm. © 2012 IEEE. DA - 2012/09/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9a738092-643f-4b56-b16a-41106a164653 ER - TY - JOUR TI - Quantitative radiolabeled biomolecule detection using a functionalized CMOS sensor DO - 10.1109/NSSMIC.2012.6551473 AU - Griffin, R. H. AU - Mozenson, O. AU - Beking, M. AU - DeRosa, M. C. AU - Lopinski, Gregory (Greg) AU - Tarr, N. G. T2 - Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2012 IEEE T2 - IEEE Nuclear Science Symposium conference record T3 - 2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record, NSS/MIC 2012, October 29 - November 3, 2012, Anaheim, CA, USA SN - 1095-7863 SN - 9781467320306 SN - 9781467320290 SN - 1467320293 SP - 6551473 SP - 2048 EP - 2052 KW - Aptamers KW - Biomolecule detection KW - CMOS imagers KW - Geant4 KW - Radiolabel KW - Adenosinetriphosphate KW - CMOS integrated circuits KW - Detectors KW - Fluorescence KW - Medical imaging KW - Nuclear physics KW - Radioactive tracers KW - Biomolecules AB - For the first time a CMOS imager has been used to detect the presence of radiolabeled target biomolecules captured on a functionalized surface. Using aptamer functionalization the system successfully detected 32P labeled adenosine triphosphate (ATP) at concentrations well below those typically associated with fluorescence-based sensor architectures. The system has also demonstrated its amenability to multiplexed biomolecule detection. Geant4, a Monte Carlo toolkit for simulating the passage of radiation through matter, was used to analyze the detector. Radiolabel detection offers the potential for direct quantitative measurement of bound biomolecules which is advantageous compared to the use of fluorescent tags. © 2012 IEEE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 23961491-97af-4d9b-afb7-19f188a8951a ER - TY - JOUR TI - A field portable neutron spectrometer based on the Bonner Sphere Principles DO - 10.1109/NSSMIC.2012.6551075 AU - Dubeau, Jacques AU - Hakmana Witharana, S. Sanjeewa AU - Atanackovic, Jovica AU - Yonkeu, André AU - Matysiak, Witold AU - Waker, Anthony J. AU - Ibrahim, Aslam AU - Archambault, John Paul T2 - Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2012 IEEE T2 - IEEE Nuclear Science Symposium conference record T3 - 2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record, NSS/MIC 2012, October 29 - November 3, 2012, Anaheim, CA, USA SN - 1095-7863 SN - 9781467320306 SN - 9781467320290 SN - 1467320293 SP - 6551075 SP - 126 EP - 130 KW - Calibration KW - Neutron detection KW - Scintillation counters KW - Ambient dose equivalent rate KW - Bonner sphere spectrometer KW - Cylindrical shell KW - Design Principles KW - Field measurement KW - Mono-energetic neutrons KW - Nuclear power reactors KW - Thermal neutron detectors KW - Measurements KW - Medical imaging KW - Moderators KW - Neutron sources KW - Neutron spectrometers KW - Nuclear physics KW - Nuclear power plants KW - Spectrometers KW - Spheres AB - The Bonner Sphere Spectrometer (BSS) has been used since 1960 for the determination of neutron energy spectra ranging from 25 meV to 20 MeV. Although some researchers have taken full sets of Bonner spheres inside nuclear power plants for field measurements, the volume and mass of the whole device have usually limited its use to laboratories and to calibration and reference facilities. The instrument presented here operates under the same principles of the Bonner spheres, except that different amounts of moderator around a thermal neutron detector are configured by adding or removing cylindrical shells. For this reason it is called the Nested Neutron Spectrometer (NNS). Thus, only the mass and volume equivalent to a single Bonner sphere need to be carried in the field. The reconfiguration of the moderator is very quick, leading to a reduced setup time. The instrument can then easily be used in the workplace and the measured spectra allow the calculation of the ambient dose equivalent rate, without the inherent inaccuracies of REM meters. The focus of this paper is the design principles of the NNS, laboratory test results and field measurements. Measurements were obtained using radionuclide neutron sources, mono-energetic neutrons from accelerators and from neutrons around the containment of a nuclear power reactor. Results are very similar for the NNS and BSS, with the former being much easier to use in the field. © 2012 IEEE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 380d94a9-e459-4ede-a9bf-f94d29e8f93b ER - TY - JOUR TI - Evaluation of very highly pixellated crystal blocks with SiPM readout as candidates for PET/MR detectors in a small animal PET insert DO - 10.1109/NSSMIC.2012.6551717 AU - Thompson, Christopher J. AU - Goertzen, Andrew L. AU - Kozlowski, Poitr AU - Retiere, Fabrice AU - Stortz, Greg AU - Sossi, Vesna AU - Zhang, Xuezhu T2 - Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2012 IEEE T2 - IEEE Nuclear Science Symposium conference record T3 - 2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record, NSS/MIC 2012, October 29 - November 3, 2012, Anaheim, CA, USA SN - 1095-7863 SN - 9781467320306 SN - 9781467320290 SN - 1467320293 SP - 6551717 SP - 3141 EP - 3145 KW - positron emission tomography KW - silicon photo-multiplier KW - small animal PET insert for MRI scanner AB - Arrays of silicon photo-multipliers (SiPMs) are good candidates for the readout of detectors in PET MR inserts due to their high packing density, efficiency, low bias voltage and insensitivity to magnetic fields. In this study we report the readout performance of SensL SiPM arrays in terms of their ability to resolve all elements of pixellated lutetium oxyorthosilicate (LYSO) crystals their energy resolution, and coincidence response function. Two SensL SPMarray-4 were used as light sensors. Two LYSO crystal blocks consisting of a arrays of 8×8 1.2 mm × 1.2 mm × 6.0 mm crystals on the lower layer and 7×7 1.2 mm × 1.2 mm × 4.0 mm crystals on the upper layer (which is offset by 1/2 the crystal width) were mounted on the SensL arrays. A second study was performed with single layer arrays of 8×8 1.2 mm × 1.2 mm × 10.0 mm crystals. All of the crystals in the dual layer block were easily identified with a peak to valley ratio of 7.2 while the single layer blocks had a peak to valley ratio of 11.2. The crystal dots were more uniformly spaced in the dual layer arrays suggesting that the inter-layer connection affords some useful light sharing. The average energy resolution for all 113 crystals was 16.3±2.3%. The coincidence response to a 0.25 mm Na-22 source in plastic was 0.97 ±0.12 mm for normally incident gamma rays with the detectors 120 mm apart. These results indicate that it should be possible to achieve a spatial resolution of about one millimetre near the center of the field of view. © 2012 IEEE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 61a211a3-b5aa-4cd3-b9ad-130d4de9bc8b ER - TY - JOUR TI - Metallic environmental effect on RF-based energy transmission DO - 10.1109/LAWP.2012.2211991 AU - Liu, Guocheng AU - Mrad, Nezih AU - Xiao, George AU - Li, Zhenzhong AU - Ban, Dayan T2 - IEEE Antennas and Wireless Propagation Letters SN - 1536-1225 VL - 11 SP - 6262449 SP - 925 EP - 928 KW - Antenna, radio frequency (RF), wireless energy transmission, wireless sensor networks AB - Radio frequency (RF)-based energy transmission enables controllable and simultaneous power delivery to wireless sensors. In such applications, RF energy transmission is likely to be affected by highly conductive (metallic) environments. Understanding metal's influence on power delivery will help improve practical implementation. This letter studies the behavior of RF energy transmission in selected scenarios by measuring return loss and peak received power. Visualized energy flow is simulated to obtain the direct picture of such scenarios. The simulation results are consistent with conclusions drawn from experimental results measured using return loss and peak received power. © 2011 IEEE. DA - 2012/08/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7af38c27-765d-4111-ab27-b305a262eb20 ER - TY - JOUR TI - The Listeria monocytogenes serotype 4b autolysin IspC has N-acetylglucosaminidase activity DO - 10.1093/glycob/cws100 AU - Ronholm, Jennifer AU - Wang, Linru AU - Hayashi, Ikue AU - Sugai, Motoyuki AU - Zhang, Zhiyi AU - Cao, Xudong AU - Lin, Min T2 - Glycobiology SN - 0959-6658 VL - 22 IS - 10 SP - 1311 EP - 1320 KW - N-acetylglucosaminidase KW - N-acetylation KW - IspC KW - peptidoglycan KW - Listeria monocytogenes AB - IspC is a novel peptidoglycan (PG) hydrolase that is conserved in Listeria monocytogenes serotype 4b strains and is involved in virulence. The aim of this study was to establish the hydrolytic bond specificity of IspC. Purified L. monocytogenes peptidoglycan was digested by recombinant IspC and the resulting muropeptides were separated by reverse phase high-performance liquid chromatography. The structure of each muropeptide was determined using matrix-assisted laser desorption ionization (MALDI)-time-of-flight mass spectrometry in combination with MALDI-post-source decay mass spectrometry. The structure of muropeptides resulting from IspC-mediated hydrolysis indicated that IspC has N-acetylglucosaminidase activity. These muropeptides also had a high proportion of N-acetylated glucosamine residues. To determine whether IspC is more effective at hydrolysing N-acetylated peptidoglycan than de-N-acetylated peptidoglycan, a peptidoglycan deacetylase (PgdA) in-frame deletion mutant was created. This mutant was shown to have fully N-acetylated peptidoglycan and was more susceptible to hydrolysis by IspC when compared with the partially de-N-acetylated wild-type peptidoglycan. This indicates that IspC is more efficient when hydrolysing a fully N-acetylated peptidoglycan substrate. The finding that IspC acts as an N-acetylglucosaminidase is consistent with its categorization, based on amino acid sequence, as a member of the GH73 family. As with other members of this family, de-N-acetylation seems to be an important mechanism for regulating the activity of IspC. © 2012 The Author. DA - 2012/06/21 PY - 2012 PB - Oxford University Press LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 337d9c05-fff0-4b73-bdc8-51910d53d64c ER - TY - JOUR TI - Unraveling the complexity of deep gas accumulations with three-dimensional multimodal CARS microscopy DO - 10.1130/G33321.1 AU - Burruss, Robert C. AU - Slepkov, Aaron D. AU - Pegoraro, Adrian F. AU - Stolow, Albert T2 - Geology SN - 0091-7613 VL - 40 IS - 12 SP - 1063 EP - 1066 KW - Coherent anti-Stokes Raman scattering KW - Deep gas KW - Fluid inclusion KW - Gas generation KW - Geological materials KW - Higher hydrocarbons KW - Hydrocarbon cracking KW - Multi-modal KW - Nonlinear optical microscopy KW - Origin of natural gas KW - Spatially resolved KW - Two-photon excited KW - C (programming language) KW - Coherent scattering KW - Methane KW - Mineralogy KW - Natural gas KW - Nonlinear optics KW - Optical microscopy KW - Organic compounds KW - Positive ions KW - Raman spectroscopy KW - Three dimensional KW - Characterization KW - fluid inclusion KW - geoaccumulation KW - hydrocarbon generation KW - three-dimensional modeling AB - The origin of natural gas accumulations in thermally mature basins is poorly understood. Unraveling complex contributions from hydrocarbon cracking, mixing, redox alteration, and deeper sources requires analysis of gases trapped during specifi c periods of basin history. Fluid inclusions can provide such samples, but their unambiguous characterization is challenging. Here we show that three-dimensional (3-D) multimodal nonlinear optical microscopy of geologic materials allows mapping and molecular identifi cation of trapped methane and water using coherent anti-Stokes Raman scattering, imaging of crystallographic features using second harmonic generation, and identifi cation of higher hydrocarbons using twophoton excited fl uorescence. Spatially resolved, molecule-specifi c characterization of fl uid inclusions will improve models of natural gas generation, migration, and accumulation. We believe that these broadly applicable methods will potentially transform the characterization of geological materials. © 2012 Geological Society of America. DA - 2012/09/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0cebedc9-78c1-480f-a167-e7b791eacab6 ER - TY - JOUR TI - Broadband 100 GHz Substrate-Integrated Waveguide couplers with irregularly shaped via holes for higher-order mode suppression AU - Dousset, David AU - Bornemann, Jens AU - Daigle, Maxime AU - Claude, Stéphane AU - Wu, Ke T2 - Microwave Conference (EuMC), 2012 42nd European T3 - 2012 42nd European Microwave Conference, EuMC 2012 - Held as Part of 15th European Microwave Week, EuMW 2012, October 29 - November 1, 2012, Amsterdam, The Netherlands SN - 978-1-4673-2215-7 SN - 978-2-87487-026-2 SP - 6459312 SP - 277 EP - 280 KW - Substrate integrated waveguide (SIW) technology, multi-branch couplers, H-plane couplers, millimeter-wave couplers AB - This paper introduces a 3 dB and a 23 dB coupler in Substrate-Integrated Waveguide (SIW) technology for future applications in radio astronomy instrumentation. In order to meet the often challenging specifications of such equipment in terms of both operating frequency and bandwidth, via holes of irregular shape are used to suppress higher-order mode excitation commonly observed in waveguide couplers. Prototypes have been manufactured and measured. For the 23 dB SIW coupler, measurements across the 85-115 GHz band show an isolation level higher than 35 dB, an average insertion loss of 3.75 dB, a coupling factor of 27 dB and a reflection coefficient better than -16.7 dB. The phase difference between the direct and coupled ports is 94.3°±2. 3°. In the 83-111 GHz band and in the case of the 3 dB coupler, isolation is higher than 20 dB, insertion losses are 4.2 dB±0.6 dB, and the reflection coefficient is better than -16.6 dB. The phase difference between the direct and coupled ports is 94.2°±2.1°. © 2012 EUROPEAN MICROWAVE ASSOC. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 845843c8-05e5-49aa-a58a-e9a42c145edf ER - TY - JOUR TI - The unexpected connection: serendipity and human mediation in networked learning AU - Kop, Rita T2 - Educational Technology and Society SN - 1176-3647 VL - 15 IS - 2 SP - 2 EP - 11 AB - Major changes on the Web in recent years have contributed to an abundance of information for people to harness in their learning. Emerging technologies have instigated the need for critical literacies to support learners on open online networks in the mastering of critical information gathering during their learning journeys. This paper will argue that people will have to adapt to using information in a new way and will advocate the movement by learners into and inside information streams on open online networks. Their own control and aggregation of information, preferably through human mediation, should provide information not only relevant to their learning, but also slightly unexpected. We will highlight why this serendipity is important in a learning context and also take three emerging technologies under the loupe; recommenders, RSS and microbloggers,and their effectiveness in supporting serendipitous learning on open online networks. © International Forum of Educational Technology & Society (IFETS). DA - 2012 PY - 2012 UR - http://www.ifets.info/journals/15_2/2.pdf LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8b75edeb-b115-4565-9060-47e73f1017c0 ER - TY - JOUR TI - (Invited) A "cook's tour" of two decades of research into the optical properties of nanostructured silicon materials DO - 10.1149/05037.0039ecst AU - Lockwood, David J. T2 - Pits and Pores 5: A Symposium in Honor of David Lockwood T2 - ECS Transactions; 50 T3 - PRiME 2012: Pits and Pores 5: A Symposium in Honor of David Lockwood, October 7-12, 2012, Honolulu, Hawaii SN - 1938-5862 SN - 978-1-62332-073-7 SN - 978-1-60768-425-1 SP - 39 EP - 54 KW - Experimental determination KW - Fundamental band gap KW - Historical account KW - Nanostructured silicon KW - Quantum confinement effects KW - Silicon nano structures KW - Strong confinement KW - Ultra-thin structures KW - Energy gap KW - Nanocrystalline silicon KW - Semiconductor quantum wells KW - Silicon oxides KW - Amorphous silicon AB - Amongst a number of diverse approaches to engineering efficient light emission in silicon nanostructures, one system that has received considerable attention has been Si/SiO2 quantum wells. Engineering such structures has not been easy, because to observe the desired quantum confinement effects, the quantum well thickness has to be less than 5 nm. Nevertheless, such ultra thin structures have now been produced by a variety of techniques. The SiO 2 layers are amorphous, but the silicon layers can range from amorphous through nanocrystalline to single-crystal form. The fundamental band gap of the quantum wells has been measured primarily by optical techniques and strong confinement effects have been observed. A detailed comparison is made between theoretical and experimental determinations of the band gap in Si/SiO2 quantum wells. The review article is prefaced with a historical account of the Pits and Pores Symposium series and a personal academic history of the author. © The Electrochemical Society. DA - 2012/12/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b258d324-3f3f-4b91-9420-776e230ae50e ER - TY - JOUR TI - Surface layers in alkaline media: nickel hydrides on metallic nickel electrodes DO - 10.1149/05031.0165ecst AU - Hall, David S. AU - Bock, Christina AU - MacDougall, Barry R. T2 - Corrosion, Passivity, and Energy: A Symposium in Honor of Digby D. Macdonald T2 - ECS Transactions T3 - PRiME 2012: Corrosion, Passivity, and Energy: A Symposium in Honor of Digby D. Macdonald, October 7-12, 2012, Honolulu, Hawaii SN - 1938-5862 SN - 9781607684190 VL - 50 IS - 31 SP - 165 EP - 179 KW - Cathodic current density KW - Hydrogen evolution reactions KW - Hydrogen generations KW - Industrial conditions KW - Industrial feedstock KW - Potentiostatic polarization KW - Reversible hydrogen electrodes KW - Water electrolysis KW - Cathodes KW - Corrosion KW - Cyclic voltammetry KW - Hydrogen production KW - X ray diffraction AB - Hydrogen generation by water electrolysis is a renewable method of producing fuel and industrial feedstock. Ni-based H2-evolution catalysts in alkaline media are low-cost alternatives to the noblemetal- based electrode materials used in acidic media. However, Ni cathodes show a significant decrease in their hydrogen evolution reaction (HER) activity after several hours of electrolysis. We consider the source of electrode deactivation on smooth metallic Ni electrodes by cyclic voltammetry (CV), galvanostatic and potentiostatic polarization, and X-ray diffraction (XRD). Below the reversible hydrogen electrode (RHE) potential, H atoms incorporate deep into the electrode material. Under industrial conditions, i.e., concentrated NaOH/KOH solutions and large cathodic current densities, α-NiHx and β-NiH x can form at the electrode surface. © The Electrochemical Society. DA - 2012/12/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 25b8957a-2a0b-45cd-8424-0e915c49ac54 ER - TY - JOUR TI - Food and interaction design: designing for food in everyday life DO - 10.1145/2212776.2212716 AU - Comber, Rob AU - Ganglbauer, Eva AU - Choi, Jaz Hee-jeong AU - Hoonhout, Jettie AU - Rogers, Yvonne AU - O'Hara, Kenton AU - Maitland, Julie T2 - CHI '12 Extended Abstracts on Human Factors in Computing Systems T3 - 30th ACM Conference on Human Factors in Computing Systems, CHI 2012, 5 May 2012 through 10 May 2012, Austin, TX SN - 9781450310161 SN - 1450310168 SP - 2767 EP - 2770 KW - alternative food cultures KW - Field studies KW - human-food-interaction KW - Interaction design KW - Positive interaction KW - Wellbeing KW - Food products KW - Health KW - Psychology computing KW - Sustainable development KW - Human engineering AB - Food and interaction design presents an interesting challenge to the HCI community in attending to the pervasive nature of food, the socio-cultural differences in food practices and a changing global foodscape. To design for meaningful and positive interactions it is essential to identify daily food practices and the opportunities for the design of technology to support such practices. This workshop brings together a community of researchers and practitioners in human-food interaction to attend to the practical and theoretical difficulties in designing for human-food interactions in everyday life. Through a practical field study and workshop we explore themes of food experiences, health and wellbeing, sustainability and alternative food cultures. © 2012 Authors. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5829b588-2e57-4b47-a1fe-5d27566112a0 ER - TY - JOUR TI - Special issue on advances in high temperature joining of materials DO - 10.1179/0008443312Z.00000000053 AU - Wanjara, Priti AU - Brochu, Mathieu AU - Farfard, Mario T2 - Canadian Metallurgical Quarterly SN - 0008-4433 VL - 51 IS - 3 SP - 237 DA - 2012/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 009c1da7-f741-4615-9962-2d853093be30 ER - TY - JOUR TI - Joining of AA1100-16 vol.-%B4C metal matrix composite using laser welding and friction stir welding DO - 10.1179/1879139512Y.0000000003 AU - Guo, J. AU - Gougeon, P. AU - Nadeau, F. AU - Chen, X.-G. T2 - Canadian Metallurgical Quarterly SN - 0008-4433 VL - 51 IS - 3 SP - 277 EP - 283 KW - Friction stir welding; Intermetallic phases; Laser welding; Mechanical properties; Metal matrix composites; Microstructure AB - This work investigated the weldability of AA1100-16B 4C (vol.-%) metal matrix composite using laser welding and friction stir welding (FSW). The microstructure and mechanical properties of joints produced by two welding techniques were compared. For laser welding, a large amount of brittle needle-like phases, together with some residues of B 4C particles were observed in the fusion zone of the joint. The use of Ti filler can improve the microstructure and increase the joint efficiency from 63 to 75%. On the other hand, the FSW, being a solid state welding technique, was interesting as it minimised the formation of brittle intermetallic phases. In addition, the breakage of B 4C particles and the grain refinement of the matrix were observed in the weld zone. The FSW joints show superior mechanical properties than the laser welded joints. Up to 100% joint efficiency can be achieved by FSW for annealed AA1100-16B 4C materials. © 2012 Canadian Institute of Mining, Metallurgy and Petroleum. AB - Ce travail a examiné la soudabilité du composite à matrice métallique AA1100-16B4C (% en vol) en utilisant le soudage au laser et le soudage par friction-malaxage (FSW). On a comparé la microstructure et les propriétés mécaniques des joints produits par les deux techniques de soudage. Pour le soudage au laser, on a observé une grande quantité de phases fragiles en forme d'aiguille ainsi que des résidus de particules de B4C, dans la zone de fusion du joint. L'utilisation de métal d'apport de Ti peut améliorer la microstructure et augmenter l'efficacité du joint de 63 à 75%. D'un autre côté, le FSW, une technique de soudage à l'état solide, était intéressant puisqu'il minimisait la formation de phases intermétalliques fragiles. De plus, on a observé, dans la zone de soudure, la rupture des particules de B4C et l'affinement de grain de la matrice. Les joints du FSW montraient des propriétés mécaniques supérieures aux joints soudés au laser. On peut obtenir une efficacité du joint jusqu'à 100% par FSW pour les matériaux recuits d'AA1100-16B4C. DA - 2012/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 74064f7b-9722-4b30-b2a4-bdc95329de19 ER - TY - JOUR TI - Adipose tissue houses different subtypes of stem cells DO - 10.1139/Y2012-094 AU - Stillwell, Chris AU - Wang, Fei AU - Xiang, Bo AU - Deng, Jixian AU - Kashour, Tarek AU - Liu, Hongyu AU - Freed, Darren AU - Arora, Rakesh C. AU - Tian, Ganghong T2 - Canadian Journal of Physiology and Pharmacology SN - 0008-4212 VL - 90 IS - 9 SP - 1295 EP - 1301 KW - adipose tissue, stem cells, differentiation, proliferation AB - Adipose tissue stromal fraction (ASF) contains multipotent cells capable of differentiation towards several lineages and may be used for the treatment of various degenerative diseases. However, the multipotent cells within ASF have not been fully characterized. In this study we have attempted to characterize stem cells in the ASF obtained through serial dilution. Five single-cell clones were studied. It was found that the single-cell clones exhibited slight but significant differences in proliferative capacity and differentiation potential. We conclude that ASF houses different subtypes of stem cells. DA - 2012/08/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 84ef40cb-5590-42a9-b365-e88e75a01ca3 ER - TY - JOUR TI - Characterization of the type III secretion associated low calcium response genes of Vibrio parahaemolyticus RIMD2210633 DO - 10.1139/w2012-109 AU - Sarty, Darren AU - Baker, Noel T. AU - Thomson, Euan L. AU - Rafuse, Cheryl AU - Ebanks, Roger O. AU - Graham, Lori L. AU - Thomas, Nikhil A. T2 - Canadian Journal of Microbiology SN - 0008-4166 VL - 58 IS - 11 SP - 1306 EP - 1315 KW - type III secretion, calcium, effector, cytotoxicity AB - Vcio parahaemolyticus T3SS-1 substrates have been identified, although many predicted substrates (based on homologies) remain undetected in secreted fractions and therefore uncharacterized. We have experimentally developed and optimized a secretion assay protocol allowing for reliable and reproducible detection of V. parahaemolyticus T3SS-1 secreted proteins within culture supernatants. The presence of magnesium and absence of calcium were critical factors in promoting type III secretion of protein substrates. Proteomic approaches identified known V. parahaemolyticus secreted effectors in addition to previously unidentified proteins. Isogenic mutants in putative low calcium response genes were generated, and experiments further implicated the genes in secretion and V. parahaemolyticus-mediated host-cell cytotoxicity during infection. These approaches should be valuable towards future detailed genetic and biochemical analyses of T3SS-1 in V. parahaemolyticus. DA - 2012/10/30 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : deb5eebb-8d48-4106-970f-29d723573cf8 ER - TY - JOUR TI - Prediction of lateral spread displacement: data-driven approaches DO - 10.1007/s10518-012-9366-7 AU - Liu, Zheng AU - Tesfamariam, Solomon T2 - Bulletin of Earthquake Engineering SN - 1570-761X VL - 10 IS - 5 SP - 1431 EP - 1454 KW - machine learning KW - Data-driven model KW - Lateral spread displacements KW - Non-parametric regression AB - Site seismic hazard (SSH) is an integral component of seismic risk assessment of engineered structures. The SSH encompasses the effect of ground shaking, landslide, and liquefaction. Discernment of liquefaction and lateral spreading vulnerability is a complex and nonlinear procedure that is influenced by model and parameter uncertainty. In this study, nine different data-driven models were investigated to predict the lateral spread displacement over a free-face and ground-slope conditions. These models include: multivariate adaptive regression splines, generalized additive model, neural networks, generalized linear model, robust regression, regression tree, support vector machine, projection pursuit, and random forest. The results demonstrate efficacy of the proposed models for lateral spreading estimation and in general, the random forest showed a better prediction. Sensitivity analysis is also performed to identify parameters that contribute to the model variability. © 2012 Crown Copyright. DA - 2012/10/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d7e3e2ad-af07-4931-811e-3f81fc2e5eea ER - TY - JOUR TI - Infrared optical imaging of matrix metalloproteinases (MMPs) up regulation following ischemia reperfusion is ameliorated by hypothermia DO - 10.1186/1471-2202-13-76 AU - Barber, Philip A. AU - Rushforth, David AU - Agrawal, Smriti AU - Tuor, Ursula I. T2 - BMC Neuroscience SN - 1471-2202 VL - 13 IS - 1 SP - 76 KW - gelatinase B KW - brain cortex KW - brain ischemia KW - brain surgery KW - enzyme activity KW - fluorescence microscopy KW - hypothermia KW - image processing KW - in vivo study KW - infrared radiation KW - middle cerebral artery occlusion KW - reperfusion injury KW - Cerebral Cortex KW - Enzyme-Linked Immunosorbent Assay KW - Functional Laterality KW - Infarction, Middle Cerebral Artery KW - Infrared Rays KW - Laser-Doppler Flowmetry KW - Metalloproteases KW - Molecular Probes KW - Up-Regulation AB - Background: We investigated the use of a new MMP activatable probe MMPSense™ 750 FAST (MMPSense750) for in-vivo visualization of early MMP activity in ischemic stroke. Following middle cerebral artery occlusion (MCAO) optical imaging was performed. Near-infrared (NIR) fluorescent images of MMPSense activation were acquired using an Olympus fluorescent microscope, 1.25x objective, a CCD camera and an appropriate filter cube for detecting the activated probe with peak excitation and emission at 749 and 775 nm, respectively. Images were acquired starting at 2 or 24 hours after reperfusion over the ipsilateral and contralateral cortex before and for 3 hours after, MMPSense750 was injected.Results: Increased intensities ipsilaterally were observed following MMPSense750 injection with ischemic injury but not in sham animals. There were significant ipsilateral and contralateral differences at 15 minutes (P <0.05) in early ischemic reperfusion and at time 0 in 24 hours post ischemia (P <0.05) which persisted at 180 minutes in both these groups (P <0.01), but not following sham surgery. The increase in ipsilateral signal intensity was attenuated by hypothermia. These observations corresponded with a significant increase in the total MMP-9 protein levels, 5 and 24 hours following ischemia reperfusion (P <0.05) and their reduction by hypothermia.Conclusions: Matrix-metalloproteinase upregulation in ischemia reperfusion can be imaged acutely in-vivo with NIRF using MMPSense750. Hypothermia attenuated both the optical increase in intensity after MMPSense750 and the increase in MMP-9 protein expression supporting the proof of concept that NIRF imaging using MMPSense can be used to assess potential therapeutic strategies for stroke treatment. DA - 2012/06/28 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9fa3b53b-b728-4b7e-80ad-1f02d9e52199 ER - TY - JOUR TI - Low-intensity pulsed ultrasound-mediated stimulation of hematopoietic stem/progenitor cell viability, proliferation and differentiation in vitro DO - 10.1007/s10529-012-0984-6 AU - Xu, Peng AU - Gul-Uludag, Hilal AU - Ang, Woon T. AU - Yang, Xiaoyan AU - Huang, Min AU - Marquez-Curtis, Leah AU - McGann, Locksley AU - Janowska-Wieczorek, Anna AU - Xing, James AU - Swanson, Eric AU - Chen, Jie T2 - Biotechnology Letters SN - 0141-5492 SN - 1573-6776 VL - 34 IS - 10 SP - 1965 EP - 1973 AB - Low-intensity pulsed ultrasound (LIPUS) stimulated the viability, proliferation and differentiation of hematopoietic stem/progenitor cells (HSPC) from fresh and cryopreserved peripheral blood leukapheresis product, as well as cord blood when applied for 10 min each day for 4 days. Cell viability, proliferation and differentiation were assessed on day 5 by viable cell counting, MTS proliferation assay, flow cytometry, and colony-forming unit assay. LIPUS stimulation: (i) enhanced the proliferation of fresh HSPC and maintained the viability of cryopreserved HSPC in vitro; (ii) did not affect the percentage of CD34 + and CD14 + cells; and (iii) enhanced burst-forming unit-erythroid colony formation. Hence, we suggest that this novel LIPUS stimulation approach might enhance the efficacy of clinical transplantation and cellular therapies using HSPC. © 2012 Springer Science+Business Media B.V. DA - 2012/10/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b285821f-285a-495d-ab55-42eeda01c774 ER - TY - JOUR TI - Integration of optical components on-chip for scattering and fluorescence detection in an optofluidic device DO - 10.1364/BOE.3.002784 AU - Watts, Benjamin R. AU - Zhang, Zhiyi AU - Xu, Chang-Qing AU - Cao, Xudong AU - Lin, Min T2 - Biomedical Optics Express SN - 2156-7085 VL - 3 IS - 11 SP - 2784 EP - 2793 KW - Fluidic components KW - Fluorescence detection KW - Functional layer KW - Microfluidic channel KW - On chips KW - Optical components KW - Optofluidic devices KW - Photonic components KW - Reliable detection KW - Photoexcitation KW - Fluorescence AB - An optofluidic device is demonstrated with photonic components integrated onto the chip for use in fluorescence and scatter detection and counting applications. The device is fabricated by integrating the optical and fluidic components in a single functional layer. Optical excitation on-chip is accomplished via a waveguide integrated with a system of lenses that reforms the geometry of the beam in the microfluidic channel into a specific shape that is more suitable for reliable detection. Separate counting tests by detecting fluorescence and scattered signals from 2.5 and 6.0 μm beads were performed and found to show detection reliability comparable to that of conventional means of excitation and an improvement over other microchip-based designs. © 2012 Optical Society of America. DA - 2012/10/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5c55188c-bf1e-44c7-b956-b2813c52baef ER - TY - JOUR TI - Spray in cross flow of a rotary atomizer DO - 10.1615/AtomizSpr.2012005049 AU - Choi, Seong Man AU - Yun, Sangsig AU - Jeong, Han Jin AU - Corber, Andrew T2 - Atomization and Sprays SN - 1044-5110 VL - 22 IS - 2 SP - 143 EP - 161 KW - Cross flows KW - Malvern KW - Rotary atomizers KW - Spray KW - Weber numbers KW - Drops KW - Fuel systems KW - Orifices KW - Speed KW - Surface mount technology KW - Flow velocity AB - This paper presents an experimental investigation of fuel sprays generated by a rotary atomizer exposed to a cross flow of air. The effects of two variables, the rotational speed and cross-flow velocity, on the droplet sizes were studied. The rotary atomizer was driven at speeds up to 15,000 rpm with a fuel flow rate of 15 kg/h and cross flow from 10 to 150 m/s. For any given rotational speed, the fuel droplet sizes decreased as the air cross flow increased, reaching an almost constant value of about 8 μm at 150 m/s cross-flow velocity. At cross-flow velocities less than about 50 m/s, the fuel droplet sizes decreased as the rotational speed increased. However, at a cross-flow velocity greater than 100 m/s, the fuel droplet sizes did not changed significantly as the rotational speed increased. Of the two variables studied, each influenced the droplet size differently in a certain cross-flow velocity region. The rotational speed influenced the droplet size at relatively low cross-flow velocity. By exceeding a cross-flow velocity of 75 m/s, the dynamic effect of high-speed cross flow became dominant. This effect can be generalized to the Weber number based on the orifice diameter and the non-dimensional droplet size. In this correlation, the following three distinct spray regimes were identified according to the Weber number based on orifice diameter: rotation dominant, intermediate, and cross flow dominant. © 2012 by Begell House, Inc. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 21eab64c-9f29-4115-aae7-ad7df96387fd ER - TY - JOUR TI - Spatial drop behavior of a rotary atomizer in a cross flow DO - 10.1615/AtomizSpr.2013007146 AU - Choi, Seong Man AU - Yun, Sangsig AU - Jeong, Han Jin AU - Corber, Andrew T2 - Atomization and Sprays SN - 1044-5110 VL - 22 IS - 12 SP - 1077 EP - 1095 KW - Cross flows KW - High-speed visualization KW - PDPA KW - Phase Doppler particle analyzer KW - Rotary atomizers KW - Sauter mean diameter (SMD) KW - Spray KW - Tangential velocities KW - Atomizers KW - Computational fluid dynamics KW - Drops KW - Flow velocity KW - Surface mount technology KW - Spray nozzles AB - This paper presents an investigation of the spatial droplet distribution around a rotary atomizer in an air cross flow. The droplet size, velocity, and spray distribution were measured using a phase Doppler particle analyzer system. The spray was photographed using a high-speed camera. The rotary atomizer was driven at speeds of 5000 rpm, 10,000 rpm, and 15,000 rpm. The fuel flow rate was held constant at 15 kg/h, and the air cross-flow velocities varied from 25 m/s to 150 m/s. The overall spray shape was observed to shrink toward the axis of rotation with increasing cross-flow speeds. High-speed visualization showed that the injected ligaments disintegrate into fairly large droplets and spread out in the radial direction at lower cross-flow velocities. At higher cross-flow speeds, the injected ligaments are abruptly deflected and broken up in the downstream direction close to the surface of the atomizer and are mixed with the cross-flow air stream immediately. The axial velocity profile indicates that a strong recirculation zone is formed just below the rotating nozzle. A high tangential velocity is shown to exist close to the injection point. Further downstream, the radial velocity component is shown to be dominant, while the tangential velocity becomes weak. The axial velocities show similar trends for the same cross-flow velocities, as the droplets follow the dominant air stream formed by the cross flow regardless of rotational speed. Near the injection orifice, relatively larger droplets are concentrated in a narrow region close to the radius of the atomizer. As the liquid jet travels downstream, the droplets are dispersed by the cross flow and distributed over a wider area. The cross flow influences the Sauter mean diameter directly; however, the rotational speed of the nozzle only has a large effect on the spray at slower cross-flow conditions. This injector design is shown to have a circumferential uniformity of ±4 μm, making it an acceptable choice for combustion applications. © 2012 by Begell House, Inc. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2b1c07d4-4dac-4a8c-ad16-640e0f736b93 ER - TY - JOUR TI - Submillimeter polarization of Galactic clouds: a comparison of 350 μm and 850 μm data DO - 10.1088/0067-0049/201/2/13 AU - Vaillancourt, John E. AU - Matthews, Brenda C. T2 - The Astrophysical Journal: Supplement Series SN - 0067-0049 VL - 201 IS - 2 SP - 13 AB - The Hertz and SCUBA polarimeters, working at 350 μm and 850 μm, respectively, have measured the polarized emission in scores of Galactic clouds. Of the clouds in each data set, 17 were mapped by both instruments with good polarization signal-to-noise ratios. We present maps of each of these 17 clouds comparing the dual-wavelength polarization amplitudes and position angles at the same spatial locations. In total number of clouds compared, this is a four-fold increase over previous work. Across the entire data set real position angle differences are seen between wavelengths. While the distribution of φ(850)-φ(350) is centered near zero (near-equal angles), 64% of data points with high polarization signal-to-noise (P ≥ 3σ p) have |φ(850)-φ(350)| > 10°. Of those data with small changes in position angle (≤10°) the median ratio of the polarization amplitudes is P(850)/P(350) = 1.7 ± 0.6. This value is consistent with previous work performed on smaller samples and models that require mixtures of different grain properties and polarization efficiencies. Along with the polarization data we have also compiled the intensity data at both wavelengths; we find a trend of decreasing polarization with increasing 850-to-350 μm intensity ratio. All the polarization and intensity data presented here (1699 points in total) are available in electronic format. © 2012. The American Astronomical Society. All rights reserved. DA - 2012/06/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 481e7b0a-646e-4bd9-94b9-98baaaff699d ER - TY - JOUR TI - On the central helium-burning variable stars of the LeoI dwarf spheroidal galaxy DO - 10.1088/2041-8205/759/1/L12 AU - Fiorentino, G. AU - Stetson, P. B. AU - Monelli, M. AU - Bono, G. AU - Bernard, E. J. AU - Pietrinferni, A. T2 - The Astrophysical Journal Letters SN - 2041-8205 VL - 759 IS - 1 SP - L12 AB - We present a study of short-period, central helium-burning variable stars in the Local Group dwarf spheroidal galaxy LeoI, including 106 RR Lyrae stars and 51 Cepheids. So far, this is the largest sample of Cepheids and the largest Cepheids to RR Lyrae ratio found in such a kind of galaxy. Comparison with other Local Group dwarf spheroidals, Carina and Fornax, shows that the period distribution of RR Lyrae stars is quite similar, suggesting similar properties of the parent populations, whereas the Cepheid period distribution in LeoI peaks at longer periods (P ∼ 1.26days instead of ∼0.5days) and spans over a broader range, from 0.5 to 1.78days. Evolutionary and pulsation predictions indicate, assuming a mean metallicity peaked within -1.5 ≲ [Fe/H] ≲ -1.3, that the current sample of LeoI Cepheids traces a unique mix of anomalous Cepheids (blue extent of the red-clump, partially electron-degenerate central helium-burning stars) and short-period classical Cepheids (blue-loop, quiescent central helium-burning stars). Current evolutionary prescriptions also indicate that the transition mass between the two different groups of stars is M HeF ∼2.1 M ⊙, and it is constant for stars metal-poorer than [Fe/H] ∼-0.7. Finally, we briefly outline the different implications of the current findings on the star formation history of LeoI. © 2012. The American Astronomical Society. All rights reserved. DA - 2012/10/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1f304354-70bd-4ae9-bade-9a0daddac470 ER - TY - JOUR TI - The small-scale physical structure and fragmentation difference of two embedded intermediate-mass protostars in Orion DO - 10.1088/0004-637X/751/2/137 AU - van Kempen, T.A. AU - Longmore, S. N. AU - Johnstone, D. AU - Pillai, T. AU - Fuente, A. T2 - The Astrophysical Journal SN - 0004-637X VL - 751 IS - 2 SP - 137 AB - Intermediate-mass (IM) protostars, the bridge between the very common solar-like protostars and the more massive, but rarer, O and B stars, can only be studied at high physical spatial resolutions in a handful of clouds. In this paper, we present and analyze the continuum results from an observing campaign at the Submillimeter Array (SMA) targeting two well-studied IM protostars in Orion, NGC2071 and L1641 S3 MMS 1. The extended SMA (eSMA) probes structure at angular resolutions up to 02, revealing protostellar disks on scales of 200AU. Continuum flux measurements on these scales indicate that a significant amount of mass, a few tens of M ⊙, is present. Envelope, stellar, and disk masses are derived using compact, extended, and eSMA configurations and compared against spectral energy distribution fitting models. We hypothesize that fragmentation into three components occurred within NGC2071 at an early time, when the envelopes were less than 10% of their current masses, e.g., <0.5 M ⊙. No fragmentation occurred for L1641 S3 MMS 1. For NGC2071, evidence is given that the bulk of the envelope material currently around each source was accreted after the initial fragmentation. In addition, about 30% of the total core mass is not yet associated to one of the three sources. A global accretion model is favored and a potential accretion history of NGC2071 is presented. It is shown that the relatively low level of fragmentation in NGC2071 was stifled compared to the expected fragmentation from a Jeans argument. Similarly, the lack of fragmentation in L1641 S3 MMS 1 is likely due to similar arguments. © 2012. The American Astronomical Society. All rights reserved.. DA - 2012/05/16 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e48a2d89-c661-45fa-8786-e8ac8b0a3f4b ER - TY - JOUR TI - Different evolutionary stages in the massive star-forming region W3 main complex DO - 10.1088/0004-637X/754/2/87 AU - Wang, Yuan AU - Beuther, Henrik AU - Zhang, Qizhou AU - Bik, Arjan AU - Rodón, Javier A. AU - Jiang, Zhibo AU - Fallscheer, Cassandra T2 - The Astrophysical Journal SN - 0004-637X VL - 754 IS - 2 SP - 87 AB - We observed three high-mass star-forming regions in the W3 high-mass star formation complex with the Submillimeter Array and IRAM 30m telescope. These regions, i.e., W3 SMS1 (W3 IRS5), SMS2 (W3 IRS4) and SMS3, are in different evolutionary stages and are located within the same large-scale environment, which allows us to study rotation and outflows as well as chemical properties in an evolutionary sense. While we find multiple millimeter continuum sources toward all regions, these three subregions exhibit different dynamical and chemical properties, which indicate that they are in different evolutionary stages. Even within each subregion, massive cores of different ages are found, e.g., in SMS2, sub-sources from the most evolved ultracompact H II region to potential starless cores exist within 30,000 AU of each other. Outflows and rotational structures are found in SMS1 and SMS2. Evidence for interactions between the molecular cloud and the H II regions is found in the 13CO channel maps, which may indicate triggered star formation. © 2012. The American Astronomical Society. All rights reserved.. DA - 2012/07/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b832ed5f-4455-4ba7-bc15-54e2453d481a ER - TY - JOUR TI - Size of the Vela pulsar's emission region at 18 cm wavelength DO - 10.1088/0004-637X/758/1/7 AU - Gwinn, C. R. AU - Johnson, M. D. AU - Reynolds, J. E. AU - Jauncey, D. L. AU - Tzioumis, A. K. AU - Hirabayashi, H. AU - Kobayashi, H. AU - Murata, Y. AU - Edwards, P. G. AU - Dougherty, S. AU - Carlson, B. AU - del Rizzo, D. AU - Quick, J. F. H. AU - Flanagan, C. S. AU - McCulloch, P. M. T2 - The Astrophysical Journal SN - 0004-637X VL - 758 IS - 1 SP - 7 AB - We present measurements of the linear diameter of the emission region of the Vela pulsar at observing wavelength λ = 18 cm. We infer the diameter as a function of pulse phase from the distribution of visibility on the Mopra-Tidbinbilla baseline. As we demonstrate, in the presence of strong scintillation, finite size of the emission region produces a characteristic W-shaped signature in the projection of the visibility distribution onto the real axis. This modification involves heightened probability density near the mean amplitude, decreased probability to either side, and a return to the zero-size distribution beyond. We observe this signature with high statistical significance, as compared with the best-fitting zero-size model, in many regions of pulse phase. We find that the equivalent FWHM of the pulsar's emission region decreases from more than 400 km early in the pulse to near zero at the peak of the pulse and then increases again to approximately 800 km near the trailing edge. We discuss possible systematic effects and compare our work with previous results. © © 2012. The American Astronomical Society. All rights reserved.. DA - 2012/09/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 49ba7e0b-cab6-47b9-8738-6639bd271f28 ER - TY - JOUR TI - Noise in the cross-power spectrum of the Vela pulsar DO - 10.1088/0004-637X/758/1/6 AU - Gwinn, C. R. AU - Johnson, M. D. AU - Reynolds, J. E. AU - Jauncey, D. L. AU - Tzioumis, A. K. AU - Dougherty, S. AU - Carlson, B. AU - Del Rizzo, D. AU - Hirabayashi, H. AU - Kobayashi, H. AU - Murata, Y. AU - Edwards, P. G. AU - Quick, J. F. H. AU - Flanagan, C. S. AU - McCulloch, P. M. T2 - The Astrophysical Journal SN - 0004-637X VL - 758 IS - 1 SP - 6 AB - We compare the noise in interferometric measurements of the Vela pulsar from ground- and space-based antennas with theoretical predictions. The noise depends on both the flux density and the interferometric phase of the source. Because the Vela pulsar is bright and scintillating, these comparisons extend into both the low and high signal-to-noise regimes. Furthermore, our diversity of baselines explores the full range of variation in interferometric phase. We find excellent agreement between theoretical expectations and our estimates of noise among samples within the characteristic scintillation scales. Namely, the noise is drawn from an elliptical Gaussian distribution in the complex plane, centered on the signal. The major axis, aligned with the signal phase, varies quadratically with the signal, while the minor axis, at quadrature, varies with the same linear coefficients. For weak signal, the noise approaches a circular Gaussian distribution. Both the variance and covariance of the noise are also affected by artifacts of digitization and correlation. In particular, we show that gating introduces correlations between nearby spectral channels. © © 2012. The American Astronomical Society. All rights reserved.. DA - 2012/09/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ac18e666-260e-4628-9cbb-9905f7165e13 ER - TY - JOUR TI - The young open clusters King 12, NGC 7788, and NGC 7790: pre-main-sequence stars and extended stellar halos DO - 10.1088/0004-637X/761/2/155 AU - Davidge, T. J. T2 - The Astrophysical Journal SN - 0004-637X VL - 761 IS - 2 SP - 155 AB - The stellar contents of the open clusters King 12, NGC 7788, and NGC 7790 are investigated using MegaCam images. Comparisons with isochrones yield an age <20 Myr for King 12, 20-40 Myr for NGC 7788, and 60-80 Myr for NGC 7790 based on the properties of stars near the main-sequence turnoff (MSTO) in each cluster. The reddening of NGC 7788 is much larger than previously estimated. The luminosity functions (LFs) of King 12 and NGC 7788 show breaks that are attributed to the onset of pre-main-sequence (PMS) objects, and comparisons with models of PMS evolution yield ages that are consistent with those measured from stars near the MSTO. In contrast, the r′ LF of main-sequence stars in NGC 7790 is matched to r′ = 20 by a model that is based on the solar neighborhood mass function. The structural properties of all three clusters are investigated by examining the two-point angular correlation function of blue main-sequence stars. King 12 and NGC 7788 are each surrounded by a stellar halo that extends out to a radius of 5 arcmin (∼3.4 pc). It is suggested that these halos form in response to large-scale mass ejection early in the evolution of the clusters, as predicted by models. In contrast, blue main-sequence stars in NGC 7790 are traced out to a radius of ∼7.5 arcmin (∼5.5 pc), with no evidence of a halo. It is suggested that all three clusters may have originated in the same star-forming complex, but not in the same giant molecular cloud. © 2012. The American Astronomical Society. All rights reserved.. DA - 2012/12/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ade51a7f-39d1-4d08-8754-75e704e837e8 ER - TY - JOUR TI - Deep Hubble Space Telescope imaging in NGC 6397: stellar dynamics DO - 10.1088/0004-637X/761/1/51 AU - Heyl, J. S. AU - Richer, H. AU - Anderson, J. AU - Fahlman, G. AU - Dotter, A. AU - Hurley, J. AU - Kalirai, J. AU - Rich, R. M. AU - Shara, M. AU - Stetson, P. AU - Woodley, K. A. AU - Zurek, D. T2 - The Astrophysical Journal SN - 0004-637X VL - 761 IS - 1 SP - 51 AB - Multi-epoch observations with the Advanced Camera for Surveys on the Hubble Space Telescope provide a unique and comprehensive probe of stellar dynamics within NGC 6397. We are able to confront analytic models of the globular cluster with the observed stellar proper motions. The measured proper motions probe well along the main sequence from 0.8 to below 0.1 M as well as white dwarfs younger than 1 Gyr. The observed field lies just beyond the half-light radius where standard models of globular cluster dynamics (e.g., based on a lowered Maxwellian phase-space distribution) make very robust predictions for the stellar proper motions as a function of mass. The observed proper motions show no evidence for anisotropy in the velocity distribution; furthermore, the observations agree in detail with a straightforward model of the stellar distribution function. We do not find any evidence that the young white dwarfs have received a natal kick in contradiction with earlier results. Using the observed proper motions of the main-sequence stars, we obtain a kinematic estimate of the distance to NGC 6397 of 2.2+0.5 - 0.7 kpc and a mass of the cluster of 1.1 ± 0.1 × 105 M at the photometric distance of 2.53 kpc. One of the main-sequence stars appears to travel on a trajectory that will escape the cluster, yielding an estimate of the evaporation timescale, over which the number of stars in the cluster decreases by a factor of e, of about 3 Gyr. The proper motions of the youngest white dwarfs appear to resemble those of the most massive main-sequence stars, providing the first direct constraint on the relaxation time of the stars in a globular cluster of greater than or about 0.7 Gyr. © 2012. The American Astronomical Society. All rights reserved.. DA - 2012/11/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : dac4a2b6-5f80-4a8a-a7d8-3b4de14ca3a7 ER - TY - JOUR TI - A new reddening law for M4 DO - 10.1088/0004-6256/144/1/25 AU - Hendricks, Benjamin AU - Stetson, Peter B. AU - VandenBerg, Don A. AU - Dall'Ora, Massimo T2 - The Astronomical Journal SN - 0004-6256 VL - 144 IS - 1 SP - 25 AB - We have used a combination of broadband near-infrared and optical Johnson-Cousins photometry to study the dust properties in the line of sight to the Galactic globular cluster M4. We have investigated the reddening effects in terms of absolute strength and variation across the cluster field, as well as the shape of the reddening law defined by the type of dust. All three aspects had been poorly defined for this system and, consequently, there has been controversy about the absolute distance to this globular cluster, which is closest to the Sun. Here, we determine the ratio of absolute to selective extinction (R V) in the line of sight toward M4, which is known to be a useful indicator for the type of dust and therefore characterizes the applicable reddening law. Our method is independent of age assumptions and appears to be significantly more precise and accurate than previous approaches. We obtain A V /E(B - V) = 3.76 ± 0.07 (random error) for the dust in the line of sight to M4 for our set of filters. That corresponds to a dust-type parameter R V = 3.62 ± 0.07 in the Cardelli et al. reddening law. With this value, the distance to M4 is found to be 1.80 ± 0.05 kpc, corresponding to a true distance modulus of (m - M) 0 = 11.28 ± 0.06 (random error). A reddening map for M4 has been created, which reveals a spatial differential reddening of δE(B - V) ≥ 0.2 mag across the field within 10′ around the cluster center; this is about 50% of the total mean reddening, which we have determined to be E(B - V) = 0.37 ± 0.01. In order to provide accurate zero points for the extinction coefficients of our photometric filters, we investigated the impact of stellar parameters such as temperature, surface gravity, and metallicity on the extinction properties and the necessary corrections in different bandpasses. Using both synthetic ATLAS9 spectra and observed spectral energy distributions, we found similarly sized effects for the range of temperature and surface gravity typical of globular cluster stars: each causes a change of about 3% in the necessary correction factor for each filter combination. Interestingly, variations in the metallicity cause effects of the same order when the assumed value is changed from the solar metallicity ([Fe/H] = 0.0) to [Fe/H] = -2.5. The systematic differences between the reddening corrections for a typical main-sequence turnoff star in a metal poor globular cluster and a Vega-like star are even stronger (5%). We compared the results from synthetic spectra to those obtained with observed spectral energy distributions and found significant differences for temperatures lower than 5000 K. We have attributed these discrepancies to the inadequate treatment of some molecular bands in the B filter within the ATLAS9 models. Fortunately, these differences do not affect the principal astrophysical conclusions in this study, which are based on stars hotter than 5000K. From our calculations, we provide extinction zero points for Johnson-Cousins and Two Micron All Sky Survey filters, spanning a wide range of stellar parameters and dust types. These extinction tables are suited for accurate, object-specific extinction corrections. © 2012. The American Astronomical Society. All rights reserved. DA - 2012/06/14 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 656cf42f-5c2f-41e3-8721-a2d4df183883 ER - TY - JOUR TI - Contaminant removal effectiveness of displacement ventilation systems during heating season: summary results from three field studies AU - Ouazia, Boualem AU - Thompson, Alexandra AU - Macdonald, Iain AU - Booth, Daniel AU - Tardif, Michel T2 - ASHRAE Transactions T3 - 2012 ASHRAE Annual Conference, June 23-27 2012, San Antonio, TX, USA SN - 0001-2505 SN - 9781936504350 VL - 118 IS - 2 SP - 292 EP - 299 KW - Carbon dioxide concentrations KW - Contaminant removal KW - Displacement ventilation KW - Displacement ventilation system KW - Field studies KW - Heating season KW - Heating system KW - Indoor air quality KW - Room air KW - Ventilation effectiveness KW - Carbon dioxide KW - Heating KW - Indoor air pollution KW - Societies and institutions KW - Ventilation AB - A series of field studies on the performance of displacement ventilation (DV) were carried out in schools across Canada during the heating season over the last three years. Indoor air quality was evaluated using the IAQ index Contaminant Removal Effectiveness (CRE) based on carbon dioxide concentrations for three schools equipped with DV systems. Results from the three field studies have shown values of CRE to be higher than 0.7 (ventilation effectiveness specified in ASHRAE 62.1-2007 when DV systems are used for heating, with ceiling return). The measured CRE in the three schools was often greater than 1.0 even in the middle of the heating season. The results show that as long as the supply air is cooler than the room air, DV system works well in achieving good contaminant stratification and ventilation effectiveness in the space when combined with a perimeter heating system. ©2012 ASHRAE. DA - 2012/12/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b984d791-ccc9-4590-8d7f-400752ebbe79 ER - TY - JOUR TI - Thermopiezoelectric response of a one-dimensional functionally graded piezoelectric medium to a moving heat source-a review DO - 10.4028/www.scientific.net/AMM.151.396 AU - Chen, Zengtao AU - Akbarzadeh, Hamid AU - Babaei, Hossein T2 - New trends in mechatronics and materials engineering: selected, peer reviewed papers from the 2011 international conference on mechatronics and materials engineering (ICMME 2011) T2 - Applied Mechanics and Materials; 151 T3 - 2011 International Conference on Mechatronics and Materials Engineering, ICMME 2011, December 10-12 2011, Qiqihar, China SN - 1660-9336 SN - 9783037853504 SP - 396 EP - 400 KW - Environmental conditions KW - Finite length KW - Fourier heat conduction KW - Functionally graded KW - Moving heat sources KW - Multi-physics KW - Non-Fourier heat conduction theory KW - Nonhomogeneity KW - Numerical example KW - Piezoelectric medium KW - Research subjects KW - Service environment KW - Smart materials and structures KW - Thermal relaxation time KW - Thermoelastic analysis KW - Thermoelastics KW - Thermopiezoelectric KW - Functionally graded materials KW - Heat conduction KW - Intelligent materials KW - MEMS KW - Piezoelectric materials KW - Thermal gradients KW - Thermal stress KW - Thermoelasticity KW - Fourier transforms AB - The multi-physics of piezoelectric materials under different environmental conditions has been an active research subject for a few decades. Particularly, the thermoelastic behaviour of smart materials and structures is of great importance to their reliability in different applications. Traditionally, the Fourier heat conduction theory was introduced in dealing with the thermoelastic reactions of smart materials and structures. This may lead to reasonable analyses and useful guidelines in design of smart structures, especially when no severe thermal gradient is involved. However, when a severe thermal gradient is indeed involved in the service environment of a smart structure, the analysing results based on the Fourier heat conduction theory is unrealistic and usually rendered useless. Non-Fourier heat conduction theories have been introduced in the thermoelastic analysis of smart materials and structures in recent years and resulted in reasonable results. In this paper, we review the recent results of a thermopiezoelectric problem of a one-dimensional (1-D), finite length, functionally graded medium excited by a moving heat source using both the Fourier and Non-Fourier heat conduction theories. Numerical examples are displayed to illustrate the effects of non-homogeneity index, length and thermal relaxation time on the results. © (2012) Trans Tech Publications, Switzerland. DA - 2012/01/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 476536a5-6db3-4ee1-9a86-b476d66122e6 ER - TY - JOUR TI - Vibration analysis based feature extraction for bearing fault detection DO - 10.4028/www.scientific.net/AMM.197.124 AU - Liu, Jie AU - Yang, Chunsheng AU - Lou, Qingfeng T2 - Applied sciences and engineering: modern topics in manufacturing and designing: selected, peer reviewed papers from the International conference on mechanical science and engineering (ICMSE 2012) T2 - Applied Mechanics and Materials; 197 T3 - International Conference on Mechanical Science and Engineering, ICMSE 2012, July 20-22 2012, Beijing, China SN - 1660-9336 SN - 9783037854723 SP - 124 EP - 128 KW - Bearing fault detection KW - Bearing fault signature KW - Catastrophic failures KW - Health condition KW - Nonstationary KW - Performance degradation KW - Research efforts KW - Rolling Element Bearing KW - Rotary machine KW - Bearings (structural) KW - Condition monitoring KW - Fault detection KW - Rotating machinery KW - Signal processing KW - Vibration analysis KW - Feature extraction AB - Rolling element bearings are widely used in various rotary machines. Most rotary machine failures are attributed to unexpected bearing faults. Accordingly, reliable bearing fault detection is critically needed in industries to prevent these machines' performance degradation, malfunction, or even catastrophic failures. Feature extraction plays an important role in bearing fault detection and significant research efforts have thus far been devoted to this subject from both academia and industry. This paper intends to provide a brief review of the recent developments in feature extraction for bearing fault detection, and the focus will be placed on the advances in methods for dealing with the nonstationary characteristics of bearing fault signatures. © (2012) Trans Tech Publications, Switzerland. DA - 2012/09/26 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f121dc26-853b-4076-9c19-aac5f434ae1f ER - TY - JOUR TI - Next-generation sequencing of microbial communities in the athabasca river and its tributaries in relation to oil sands mining activities DO - 10.1128/AEM.02036-12 AU - Yergeau, Etienne AU - Lawrence, John R. AU - Sanschagrin, Sylvie AU - Waiser, Marley J. AU - Korber, Darren R. AU - Greer, Charles W. T2 - Applied and Environmental Microbiology SN - 0099-2240 VL - 78 IS - 21 SP - 7626 EP - 7637 KW - 16S rRNA gene KW - Aquatic microbial communities KW - Archaea KW - Archaeal KW - Athabasca KW - Athabasca oil sands KW - Bacterial diversity KW - Bitumen extraction KW - Environmental studies KW - Microbial communities KW - Oil sands mining KW - Oil sands tailings KW - Tailings pond KW - Bituminous materials KW - Microorganisms KW - Oil sands KW - Ore tailings KW - RNA KW - Sedimentology KW - sediments KW - RNA 16S KW - bioindicator KW - fluvial deposit KW - physicochemical property KW - prokaryote KW - river pollution KW - species diversity KW - archaeon KW - bacterium KW - biodiversity KW - DNA sequence KW - environmental monitoring KW - genetics KW - high throughput sequencing KW - microbial consortium KW - microbiology KW - oil and gas field KW - oil spill KW - water pollutant KW - Oil and Gas Fields KW - Petroleum Pollution KW - Rivers KW - RNA, Ribosomal, 16S KW - Sequence Analysis, DNA KW - Water Pollutants, Chemical KW - Alberta KW - Athabasca River KW - Canada KW - Archaea KW - Bacteria (microorganisms) AB - The Athabasca oil sands deposit is the largest reservoir of crude bitumen in the world. Recently, the soaring demand for oil and the availability of modern bitumen extraction technology have heightened exploitation of this reservoir and the potential unintended consequences of pollution in the Athabasca River. The main objective of the present study was to evaluate the potential impacts of oil sands mining on neighboring aquatic microbial community structure. Microbial communities were sampled from sediments in the Athabasca River and its tributaries as well as in oil sands tailings ponds. Bacterial and archaeal 16S rRNA genes were amplified and sequenced using next-generation sequencing technology (454 and Ion Torrent). Sediments were also analyzed for a variety of chemical and physical characteristics. Microbial communities in the fine tailings of the tailings ponds were strikingly distinct from those in the Athabasca River and tributary sediments. Microbial communities in sediments taken close to tailings ponds were more similar to those in the fine tailings of the tailings ponds than to the ones from sediments further away. Additionally, bacterial diversity was significantly lower in tailings pond sediments. Several taxonomic groups of Bacteria and Archaea showed significant correlations with the concentrations of different contaminants, highlighting their potential as bioindicators. We also extensively validated Ion Torrent sequencing in the context of environmental studies by comparing Ion Torrent and 454 data sets and by analyzing control samples. © 2012, American Society for Microbiology. DA - 2012/08/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0dc389f0-c6fb-4e63-9b97-63b1fe7ea604 ER - TY - JOUR TI - Subjective fidelity assessment of rotorcraft training simulators AU - Timson, Emma AU - Perfect, Philip AU - White, Mark AU - Padfield, Gareth D. AU - Erdos, Robert AU - Gubbels, Arthur W. T2 - 68th American Helicopter Society international annual forum 2012 : Fort Worth, Texas, USA, 1-3 May 2012. T3 - American Helicopter Society 68th Annual Forum, May 1-3, 2012, Fort Worth, TX, USA SN - 1622760514 SN - 9781622760510 VL - 3 SP - 2118 EP - 2133 KW - Level-1 KW - Potential applications KW - Qualification standards KW - Simulation fidelity KW - Subjective assessments KW - Task strategy KW - Training simulator KW - Transport delay KW - Helicopter rotors KW - Helicopters KW - Rotors KW - Simulators AB - This paper describes the potential applications of a Simulation Fidelity Rating (SFR) scale, to support the subjective assessment of rotorcraft training simulators. In this paper, the SFR scale has been used to examine pilot sensitivity and subsequent task strategy adaptation to simulator transport delay variations in the Precision Hover manoeuvre. The current FAA AC 120-63 and JAR-FSTD H simulator qualification standards requires a transport delay of no more than 100ms to meet the most stringent Level D criteria. The study has highlighted that the majority of the evaluation pilots indicated that transport delays of this order would compromise the utility of the simulator to provide training for the Precision Hover manoeuvre. For an additional 100ms transport delay, the pilot's SFRs ranged from Level 1 fidelity (simulation fit for purpose) to Level 3 fidelity (simulation not fit for purpose). The factors influencing the SFRs awarded, and their impact on the application of the SFR scale, are discussed in this paper. The methodology detailed in this paper has potential for more objective quantification of the utility of rotorcraft training simulators. Copyright ©2012 by the American Helicopter Society Inc. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 97fe1690-9dec-4580-9dbc-488011051677 ER - TY - JOUR TI - The atomic structure of deuterated boyleite ZnSO4·4D2O, ilesite MnSO4·4D2O, and bianchite ZnSO4·6D2O DO - 10.2138/am.2012.4121 AU - Anderson, Jennifer L. AU - Peterson, Ronald C. AU - Swainson, Ian T2 - American Mineralogist SN - 0003-004X VL - 97 IS - 11-12 SP - 1905 EP - 1914 KW - chemical bonding KW - crystal structure KW - crystallography KW - neutron diffraction KW - sulfate group AB - Deuterated boyleite ZnSO 44D 2O, was synthesized and the atomic structure, including D positions, was successfully refined in a combined histogram neutron diffraction refinement. The cell dimensions for boyleite are a = 5.9144(2), b = 13.5665(4), c = 7.8924(2) Å, and β = 90.668(2)° with space group P2 1/n and Z = 4. The atomic structure including D positions of the isostructural mineral ilesite, MnSO 4·4D 2O, was refined and the cell dimensions are a = 5.9753(1), b = 13.8186(3), c = 8.0461(1) Å, and β = 90.826(2)°. Deuterated bianchite ZnSO 4·6D 2O was synthesized and the atomic structure, including D positions, was successfully refined with a unit cell of a = 9.969(1), b = 7. 2441(7), c = 24.249(3) Å, and β = 98.488(5)° in space group C2/c and Z = 8. A comparison of the hydrogen bonding in M 2+SO 4·4D 2O with that in M 2+SO 4·6D 2O shows that bifurcated hydrogen bonds are common in the tetrahydrate sulfates but nonexistent in the hexahydrate structures. This is a result of the packing constraints of the rings of the sulfate and metal-containing octahedra in the tetrahydrates. In the hexahydrate sulfates there is no direct linkage between the sulfate and metal-containing octahedra and hydrogen bonds are optimized without packing constraints, and no bifurcated hydrogen bonds are observed. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e4b5c982-2ec3-4527-89f1-a2f9a3329c67 ER - TY - JOUR TI - A hybrid fuzzy logic proportional-integral-derivative and conventional on-off controller for morphing wing actuation using shape memory alloy: part 1, morphing system mechanisms and controller architecture design DO - 10.1017/S0001924000006977 AU - Grigorie, T. L. AU - Botez, R. M. AU - Popov, A. V. AU - Mamou, M. AU - Mébarki, Y. T2 - The Aeronautical Journal SN - 0001-9240 VL - 116 IS - 1179 SP - 433 EP - 449 KW - Actuation systems KW - Closed loop architecture KW - Controller architectures KW - Defuzzifiers KW - Design phase KW - Fuzzy logic controllers KW - Fuzzy models KW - Hybrid actuation KW - Hybrid controller KW - Input-output mapping KW - Internal loops KW - Morphing KW - Morphing wings KW - Open loops KW - Output current KW - Proportional integral derivatives KW - S-function KW - Skin surfaces KW - SMA actuators KW - Strong nonlinearity KW - System architectures KW - Transition locations KW - Wing trailing edge KW - Fuzzy logic KW - Membership functions KW - Microactuators KW - Proportional control systems KW - Shape memory effect KW - Flexible wings AB - The present paper describes the design of a hybrid actuation control concept, a fuzzy logic proportional-integral-derivative plus a conventional on-off controller, for a new morphing mechanism using smart materials as actuators, which were made from shape memory alloys (SMA). The research work described here was developed for the open loop phase of a morphing wing system, whose primary goal was to reduce the wing drag by delaying the transition (from laminar to fully turbulent flows) position toward the wing trailing edge. The designed controller drives the actuation system equipped with SMA actuators to modify the flexible upper wing skin surface. The designed controller was also included, as an internal loop, in the closed loop architecture of the morphing wing system, based on the pressure information received from the flexible skin mounted pressure sensors and on the estimation of the transition location. The controller's purposes were established following a comprehensive presentation of the morphing wing system architecture and requirements. The strong nonlinearities of the SMA actuators' characteristics and the system requirements led to the choice of a hybrid controller architecture as a combination of a bi-positional on-off controller and a fuzzy logic controller (FLC). In the chosen architecture, the controller would behave as a switch between the SMA cooling and heating phases, situations where the output current is 0A or is controlled by the FLC. In the design phase, a proportional-integral-derivative scheme was chosen for the FLC. The input-output mapping of the fuzzy model was designed, taking account of the system's error and its change in error, and a final architecture for the hybrid controller was obtained. The shapes chosen for the inputs' membership functions were s-function, π-function, and z-function, and product fuzzy inference and the center average defuzzifier were applied (Sugeno). DA - 2012/05 PY - 2012 PB - Cambridge University Press LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 09754f89-50a9-46b8-b57c-53c657e4118c ER - TY - JOUR TI - A hybrid fuzzy logic proportional-integral-derivative and conventional on-off controller for morphing wing actuation using shape memory alloy: part 2, controller implementation and validation AU - Grigorie, Teodor Lucian AU - Botez, Ruxandra Mihaela AU - Popov, Andrei Vladimir AU - Mamou, Mahmoud AU - Mébarki, Youssef T2 - The Aeronautical Journal SN - 0001-9240 VL - 116 IS - 1179 SP - 451 EP - 465 KW - Aerodynamic forces KW - Controller implementation KW - Data acquisition cards KW - Experimental bench KW - Experimental validations KW - Hybrid actuation KW - Hybrid controller KW - Laboratory conditions KW - Linear variable differential transformer KW - Matlab/Simulink software KW - Morphing wings KW - Output channels KW - Physical model KW - Position detection KW - Power supply KW - Proportional integral derivatives KW - Simulation and validation KW - SMA wire KW - Switching power supplies KW - Transition point KW - Wind tunnel tests KW - Actuators KW - Aerodynamics KW - Data acquisition KW - Electric power supplies to apparatus KW - Fuzzy logic KW - Power electronics KW - Shape memory effect KW - Thermocouples KW - Visualization KW - Voltage dividers KW - Proportional control systems AB - The paper presents the numerical and experimental validation of a hybrid actuation control concept - fuzzy logic proportional-integral-derivative (PID) plus conventional on-off - for a new morphing wing mechanism, using smart materials made of shape memory alloy (SMA) as actuators. After a presentation of the hybrid controller architecture that was adopted in the Part 1, this paper focuses on its implementation, simulation and validation. The PID on-off controller was numerically and experimentally implemented using the Matlab/Simulink software. Following preliminary numerical simulations which were conducted to tune the controller, an experimental validation was performed. To implement the controller on the physical model, two programmable switching power supplies (AMREL SPS100-33) and a Quanser Q8 data acquisition card were used. The data acquisition inputs were two signals from linear variable differential transformer potentiometers, indicating the positions of the actuators, and six signals from thermocouples installed on the SMA wires. The acquisition board's output channels were used to control power supplies in order to obtain the desired skin deflections. The experimental validation utilised an experimental bench test in laboratory conditions in the absence of aerodynamic forces, and a wind-tunnel test for different actuation commands. Simultaneously, the optimised aerofoils were experimentally validated with the theoreticallydetermined aerofoils obtained earlier. Both the transition point real time position detection and visualisation were realised in wind tunnel tests. DA - 2012/05 PY - 2012 PB - Royal Aeronautical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2061a465-d574-4711-8097-66b12cd76159 ER - TY - JOUR TI - Exploring how social media can enhance the teaching of action research DO - 10.1177/1476750311424945 AU - Carroll, Fiona AU - Jenkins, Alyson AU - Woodward, Clare AU - Kop, Rita AU - Jenkins, Emrys T2 - Action Research SN - 1476-7503 VL - 10 IS - 2 SP - 170 EP - 188 AB - Action research has an extensive history of being used to improve teaching and learning in many different professional settings, for example, schools, colleges, universities health and social care services. Educational action research embodies a process that necessitates honesty and openness and which lends itself to the betterment of one's practice; in the current e-learning climate, where education is rapidly changing and the role and practice of the educator is evolving yet uncertain, action research has never been more valuable. This article explores and presents how social media have been used to enhance the teaching of action research and also how students gained an understanding, appreciation and an evolving experience of action research. Exploring the intricate relationships between action research, new technologies and the learning that took place during an Understanding Action Research module, this article is written from the perspective that the module team was interested in ensuring that students acquired a fully rounded understanding of action research in order to utilize it in the improvement of their own practice. © The Author(s) 2011 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav. DA - 2012/10/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ff1cc8f1-751b-43db-81e4-e4f63a9141b9 ER - TY - JOUR TI - The flight dynamics of Tapejara, a pterosaur from the early cretaceous of Brazil with a large cranial crest DO - 10.1111/1755-6724.12007 AU - Chatterjee, Sankar AU - Templin, R. Jack T2 - Acta Geologica Sinica - English Edition SN - 0001-5717 VL - 86 IS - 6 SP - 1377 EP - 1388 KW - aerodynamics KW - cliff KW - computer simulation KW - Cretaceous KW - feather KW - female behavior KW - flight activity KW - functional morphology KW - gravity field KW - mate choice KW - paleontology KW - pterosaur KW - sexual dimorphism KW - wing morphology KW - Brazil KW - Pterodactyloidea KW - Tapejara AB - Tapejara wellnhoferi, a small azhdarchoid pterodactyloid from the Early Cretaceous Santana Formation of Brazil, provides critical information about the aerodynamic function of its spectacular head crest. The cranial crests in pterodactyloids were sexually dimorphic and are thought to have evolved in adult males in response to female mate choice. However, the location of cranial crests in front of the center of gravity would create instability in the yaw axis during flight and may seem like a handicap. Vertically aligned webbed feet probably suppressed the yawing rotations and instability from the crest. Here we show that the crest functioned as a front rudder to make agile turn and mediate flight control. A computer simulation model suggests that Tapejara had a large excess of muscle power available above the power required for continuous flapping flight. It could easily takeoff from a perch, ground, or water surface and land safely on the ground. It was an excellent glider with a gliding angle close to 4° and a cruising speed of 27 km/h. Tapejara could soar efficiently on the windward side of cliffs or circle on rising thermals over tropical waters for efficient long-distance flight. Various control surfaces in the wings of Tapejara analogous to the slat, aileron, elevator, fin, rudder, and horizontal stabilizer of an aircraft made pterodactyloids versatile flyers. DA - 2012/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c7c02eeb-c24f-47a5-a2c3-d0a636b31a3b ER - TY - JOUR TI - A comparative study on mechanical and electrical properties of SWCNT-modified epoxy resins and their end-use applications DO - 10.2514/6.2012-1725 AU - Ashrafi, Behnam AU - Jakubinek, Michael B. AU - Martinez-Rubi, Yadienka AU - Simard, Benoit AU - Johnston, Andrew T2 - 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference 2012 T2 - Collection of Technical Papers - Structures, Structural Dynamics and Materials Conference (AIAA/ASME/ASCE/AHS/ASC) T3 - 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference 2012, April 23-26, 2012, Honolulu, Hawaii SN - 0273-4508 SN - 9781600869372 KW - Electrical conductivity KW - Electrical resistances KW - Interlaminar fracture toughness KW - Interlaminar properties KW - Mechanical and electrical KW - Mechanical and electrical properties KW - Mechanical performance KW - Mode-i fracture toughness KW - Aluminum KW - Epoxy resins KW - Fracture toughness KW - Resins KW - Structural dynamics KW - Electric conductivity AB - In this work, the influence of SWCNTs on electrical and mechanical performance of two epoxy resins was studied. In the first study, a small quantity of SWCNTs (0.125 wt%) was incorporated into a high-temperature aerospace-grade epoxy. After the modification with SWCNTs, the correlation between bulk properties of this epoxy (electrical conductivity and Mode I fracture toughness) and the properties of epoxy/glass fiber laminates (inplane/ transverse electrical conductivity and Mode I interlaminar fracture toughness) was investigated. It was found that the electrical property improvements of nano-modified laminates exceeded those of bulk SWCNT-modified epoxy. On the other hand, the fracture toughness improvement of bulk epoxy after the addition of SWCNTs did not translate into interlaminar properties enhancement, possibly due to reduction of the nano-modified resin's ability to interact with glass fiber mats. In the second study, the mechanical and electrical performance of a SWCNT-modified epoxy adhesive was studied for aluminum-to-aluminum bonding. It was found that the integration of 1 wt% SWCNTs can considerably improve joint Mode I fracture toughness by ~ 35% due to mechanisms such as crack bridging. The electrical resistance of the bondline was also consistent with the electrical conductivity of SWCNT-modified adhesive films (~10-3 S/m), but somewhat lower than the bulk electrical conductivity measured on thicker samples. © 2012 by Canada National Research Council. DA - 2012/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 769fe6ed-22fb-4a2c-b4f0-015472a66d7a ER - TY - JOUR TI - Thermocapillary migration of a deformable droplet AU - Samareh, B. AU - Mostaghimi, J. AU - Moreau, C. T2 - 6th International Conference on Thermal Engineering Theory and Applications T3 - 6th International Conference on Thermal Engineering Theory and Applications, May 29 - June 1, 2012, Istanbul SN - 9781926769080 KW - Computational uncertainties KW - Conservation equations KW - Energy equation KW - Fluorinert KW - Immiscible fluids KW - Interface shape KW - Interfacial heat transfer KW - Marangoni force KW - Marangoni numbers KW - Migration velocity KW - Silicon oil KW - Thermal boundary layer KW - Thermocapillary migration KW - Three-dimensional volume KW - Tracking scheme KW - Variable surface tension KW - Volume tracking method KW - Capillary flow KW - Heat transfer KW - Surface tension KW - Thermoanalysis KW - Drops AB - In the present study a parallel three dimensional Volume of Fluid (VOF) method is developed to simulate Marangoni force in immiscible fluids with variable surface tension. Conservation equations are solved based on cell-averaged one-field volume tracking scheme. Evaluating the convective term in the energy equation along the boundary between the fluids highly depends on the position and orientation of the interface; hence, using average cell values simply ignores the interface shape and leads to computational uncertainty. As a remedy to this issue, the original idea behind the volume tracking method is used not only to advect mass and momentum but also energy across cells. To verify the proposed algorithm, results are compared against theoretically predicted thermocapillary migration velocity of a droplet at the limit of zero Marangoni number. However, at relatively high Marangoni numbers, thermal boundary layers are very thin and challenging to resolve. To demonstrate the capabilities of the heat transfer module, simulation of a Fluorinert droplet moving in silicon oil under applied temperature gradient in microgravity is compared against the available experimental results and the migration velocity of the droplet is reported. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : eb37d6fe-1844-49bf-ab50-ed0575b3c477 ER - TY - JOUR TI - Particle size effects on ice crystal accretion DO - 10.2514/6.2012-3039 AU - Knezevici, Daniel C. AU - Fuleki, Dan AU - Currie, Tom C. AU - MacLeod, James D. T2 - 4th AIAA Atmospheric and Space Environments Conference 2012 T3 - 4th AIAA Atmospheric and Space Environments Conference 2012, June 25-28, 2012, New Orleans, LA, USA SN - 9781624101922 SN - 978-1-62276-218-7 SP - 603 EP - 611 KW - Ice crystals KW - Particle size effect KW - Test apparatus KW - Wet bulb temperature KW - Particle size KW - Phase transitions KW - Ice AB - This paper describes the commissioning of a new test apparatus intended to simulate an inner-compressor duct bleed slot. It also identifies, for the first time, that ice crystal particle size plays an important role in the ice crystal phenomenon. Data and sample images of accretion are presented for wet bulb temperatures near freezing. The effect of wet bulb temperature and particle size on the natural melting of ice crystals is investigated. In addition, the erosion of surface accretion by ice crystal particles is discussed. © 2012 by Her Majesty the Queen in Right of Canada. Published by the American Institute of Aeronautics and Astronautics, Inc. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ab66a47b-e9ee-4163-8bb6-b8875da405d9 ER - TY - JOUR TI - Wake vortex encounter aircraft and underwing pod loads DO - 10.2514/6.2012-2673 AU - Brown, Anthony P. T2 - 4th AIAA Atmospheric and Space Environments Conference 2012 T3 - 4th AIAA Atmospheric and Space Environments Conference 2012, June 25-28, 2012, New Orleans, LA, USA SN - 9781624101922 SN - 978-1-62276-218-7 SP - 40 EP - 49 KW - Aircraft emissions KW - Aircraft wakes KW - Critical loading KW - Flight research KW - Pod development KW - Safety limits KW - Wake turbulence KW - Wake vortex KW - Aircraft KW - Atmospheric thermodynamics KW - Bolts KW - Loading KW - Mountings KW - Turbulence KW - Wakes AB - THE NRC CT-133 aircraft has been used for wake turbulence research, over a period of five years. More recently, underwing sensor pod development has been completed, for the conduct of jet aircraft emission flight research, with the intention of being able to fully measure various aspects of emissions holistically, over the whole of the aircraft wake regimes. Critical airworthiness issues included the loads that the aircraft and pods would be subjected to, in the wake turbulence regimes of wakes, and the trailing-pair wake vortex regime in particular. NRC CT-133 wake turbulence data without the pods has been analysed and transformed to the pod CG locations, and resulting reactions derived for the pod mounting rack attachment bolt locations, the critical loading points. The resulting pod mounting rack attachment bolt loads have been parametrically related for wake turbulence parameters. When installed, the pods were fitted with accelerometers and accelerations measured, from which loads have been derived. These loads have been compared with those estimated for wake vortex encounter data without the pods. The pods mounting bolts loads were within the airworthiness safety limit. © 2012 by The Crown in Right of Canada. Published by the American Institute of Aeronautics and Astronautics, Inc. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b71d8ee1-9d0c-42f2-9066-6de1a9fb78d9 ER - TY - JOUR TI - Aviation emissions index derivation methodologies from flight data, including black carbon and aerosols DO - 10.2514/6.2012-2926 AU - Brown, Anthony P. AU - Bastian, Matthew AU - Smallwood, Greg AU - O'Brien, Jason T2 - 4th AIAA Atmospheric and Space Environments Conference 2012 T3 - 4th AIAA Atmospheric and Space Environments Conference 2012, June 25-28, 2012, New Orleans, LA, USA SN - 9781624101922 SN - 978-1-62276-218-7 SP - 288 EP - 298 KW - Aerosol emissions KW - Air temperature measurement KW - Comparative measurements KW - Condensation nuclei KW - Oxides of nitrogen KW - Pollutant species KW - Runway operations KW - Volatile organic compound (VOC) KW - Aerosols KW - Aviation KW - Exhaust systems (engine) KW - Jet engines KW - Temperature measurement KW - Volatile organic compounds KW - Wakes KW - Atmospheric thermodynamics AB - The NRC has undertaken aviation emissions flight research. Principally aimed at Heavy and Super Jet Transports, the project has applied the NRC T-33 to measure condensation nuclei (CN), black carbon (BC), volatile organic compounds (VOC) and oxides of nitrogen (NOy) from aircraft flying enroute at high altitude. Most recently, the T-33 and flight profiles, developed under the research, have been applied to the comparative measurement of jet biofuel emissions. During the course of the project, techniques have been developed, for the derivation of estimated Emission Indices (EI) of pollutant species, measured on the ground (during taxy, departure or arrival runway operations) or inflight. In particular, if the jet engine exhaust jet streams were very young, air temperature measurements were used to correlate to empirically modeled turbulent jet mixing fluid dynamics, thereby deriving the applicable dilution factors (DF) to apply to the measured concentrations. For exhaust plumes which were not very young (i.e. not in a state of turbulent mixing, but rather in a state of turbulent or quiescent diffusion), flight data has involved techniques for the full cross-sectional measurement of wakes, including jet wake and wake vortex regimes. Not only has this captured the nature of wake structures under very strong static and dynamic influences, but permitted the measurement of aerosol emission index numbers directly. © 2012 by The Crown in Right of Canada. Published by the American Institute of Aeronautics and Astronautics, Inc. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 81519307-87fe-4c08-91ad-fdf94ad82f44 ER - TY - JOUR TI - Fundamental study of mixed-phase icing with application to ice crystal accretion in aircraft jet engines DO - 10.2514/6.2012-3035 AU - Currie, Thomas C. AU - Struk, Peter M. AU - Tsao, Jen-Ching AU - Fuleki, Dan AU - Knezevici, Daniel C. T2 - 4th AIAA Atmospheric and Space Environments Conference 2012 T3 - 4th AIAA Atmospheric and Space Environments Conference 2012, June 25-28, 2012, New Orleans, LA, USA SN - 9781624101922 SN - 978-1-62276-218-7 SP - 523 EP - 539 KW - Aircraft jet engines KW - Evaporative cooling KW - Fundamental studies KW - Ice water content KW - National Research Council of Canada KW - Nonlinear functions KW - Total temperatures KW - Wet bulb temperature KW - Airfoils KW - Atmospheric humidity KW - Atmospheric temperature KW - Deposits KW - Evaporative cooling systems KW - Functions KW - Jet engines KW - Ice AB - This paper describes experiments performed in an altitude chamber at the National Research Council of Canada (NRC) as the first phase of a joint NRC/NASA program investigating ice crystal accretion in aero engines. The principal objective was to explore the effect of wet bulb temperature Twb (dependent on air temperature, humidity and pressure) on accretion behavior, since preliminary results published in an earlier paper indicated that well-adhered accretions are only possible at Twb<0°C, when water in an impinging mixedphase flow can freeze to a surface. To assess the accretion sensitivity to Twb, the symmetrical airfoil used in the previous work was tested at pressures of 44.8 kPa and 93kPa, usually at 0.25 Mach number, over a range of freestream liquid water and ice water concentrations, total air temperatures and humidity levels. Twb was typically maintained at +2°C or -2°C, based on dry total conditions (i.e. without ice or water injection). Total air temperature was >0°C in all tests. The limited test results confirmed that accretion behavior is very sensitive to Twb, which is in turn strongly related to pressure since evaporative cooling increases with decreasing pressure. Humidity and total temperature did not appear to have an independent effect on accretion behavior. Accretions, often resembling glaze ice, formed at Twb<0°C, when freestream water would freeze on the test airfoil without ice crystals present in the freestream. At Twb>0°C ice deposits were observed to be slushy, poorly adhered and shed frequently. The size of such deposits appeared to be a non-linear function of the freestream ice water content (IWC), becoming much larger at high IWC. © 2012 by National Research Council of Canada. Published by the American Institute of Aeronautics and Astronautics, Inc. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7b1665a0-bcc9-4a6d-8116-311e825173e5 ER - TY - JOUR TI - Inflight cold-soaked fuel frost observations and analysis DO - 10.2514/6.2012-3233 AU - Brown, Anthony P. T2 - 4th AIAA Atmospheric and Space Environments Conference 2012 T3 - 4th AIAA Atmospheric and Space Environments Conference 2012, June 25-28, 2012, New Orleans, LA, USA SN - 9781624101922 SN - 978-1-62276-218-7 SP - 736 EP - 748 KW - Aerodynamic characteristics KW - Frost deposition KW - Jet transports KW - Roughness effects KW - Deposition KW - Transport aircraft AB - Observations of occurrences of inflight cold-soaked fuel frost (CSFF) on the wings of jet transport aircraft are presented and discussed, together with weather observational records. Although potentially rare occurrences, it would appear that such inflight frost deposition is not unique. Nor are the aerodynamic characteristics of jet transport wings protected in any way, from the roughness effect of inflight frost deposition. © 2012 by The Crown in Right of Canada. Published by the American Institute of Aeronautics and Astronautics, Inc. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 59df78ed-7395-4714-8265-e996185f781b ER - TY - JOUR TI - Icing wind tunnel tests of a contaminated supercritical anti-iced wing section during simulated take-off - Phase 2 DO - 10.2514/6.2012-2799 AU - Clark, Catherine AU - MacMaster, Marc T2 - 4th AIAA Atmospheric and Space Environments Conference 2012 T3 - 4th AIAA Atmospheric and Space Environments Conference 2012, June 25-28, 2012, New Orleans, LA, USA SN - 9781624101922 SN - 978-1-62276-218-7 SP - 245 EP - 259 KW - Freezing rain KW - National Research Council KW - Ontario , Canada KW - Rotation speed KW - Supercritical KW - Supercritical airfoils KW - Wind tunnel tests KW - Winter precipitation KW - Rain KW - Takeoff KW - Wind stress KW - Wings KW - Wind tunnels AB - Icing wind tunnel tests were conducted at the National Research Council Canada's 3 m x 6 m Propulsion and Icing Wind Tunnel (PIWT) located in Ottawa, Ontario, Canada early in 2011 and 2012. These tests were a continuation of the work performed in 2010 on a generic supercritical airfoil representative of a regional-jet type aircraft wing section. Tests nominally consisted of coating the wing with de/anti-icing fluid, applying various levels of precipitation (e.g., snow, ice pellets, freezing rain, or combinations thereof), and simulating a take-off condition in the wind tunnel by accelerating the wind speed and pitching the wing through a desired pitch-profile. The wing performance was evaluated primarily by the measured lift-loss relative to the lift generated by a clean wing. The second phase of testing consisted of test cases similar to the 2010 tests in order to expand the scope of the data sets at various temperatures, while also investigating the effects of the rotation speed and ramp time on lift-loss and the effects of fluids and precipitation on stall. The experimental results were used as guidance for regulators in determining holdover and allowance times for aircraft operating in winter precipitation. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 012ea6d1-1964-4314-aedb-c474838907ff ER - TY - JOUR TI - Trailing vortex formation by lifting-line field induction and centrifugal stability analyses DO - 10.2514/6.2012-2671 AU - Brown, Anthony P. T2 - 4th AIAA Atmospheric and Space Environments Conference 2012 T3 - 4th AIAA Atmospheric and Space Environments Conference 2012, June 25-28, 2012, New Orleans, LA, USA SN - 9781624101922 SN - 978-1-62276-218-7 SP - 11 EP - 21 KW - Centrifugal stabilities KW - Cylindrical coordinates KW - Expansion pressure KW - Field calculation KW - Flight measurements KW - Induced velocity KW - Potential vortex KW - Spanwise distribution KW - Centrifugation KW - Euler equations KW - Loading KW - Velocity KW - Vorticity KW - Vortex flow AB - Analyses of Wake Vortex formation and downstream development have been conducted, using mutual field induction calculations of the shed vorticity sheet. In order to illustrate and compare the formation and downstream development of wingtip vortices, the analyses were conducted for two widely-different cases of spanwise distribution of bound-vorticity. Termed inboard and outboard distributions, the loadings were nearly triangular and rectangular, respectively. For development analysis, Biot-Savart field calculations were conducted for the induced velocity field, and hence displacement of the elements of the shed vorticity sheet. Although an induced field calculation does not represent all fluid-element forces (in particular, the expansion pressure field) and thus, might over-estimate core radius for example), the comparative calculations provided results of interest, regarding the properties of developed wingtip vortices, such as core radius, span location, core asymmetry and peak velocity location. Following this and with reference to the NRC flight measurements of small, intense vortex elements with peaks greater than potential vortex peaks, centrifugal stability analysis is conducted, using a number of models: (1) the developed vortices for the outboard loading case were stimulated with, and released from, radial forcing; (2) a physical model of the centrifugal balance between inertia and pressure forces was examined by time-wise solution of the equations of elemental equations of motion, and (3) the Euler equations in axisymmetric, cylindrical coordinate form were numerically, spatiotemporally solved for excess-velocity vortex profiles. An example of resultant radial flow behaviour is compared to flight data. © 2012 by The Crown in Right of Canada. Published by the American Institute of Aeronautics and Astronautics, Inc. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f6406311-f230-485e-96d7-caa1ae3830b0 ER - TY - JOUR TI - Enroute flight data of wake vortex core profiles and properties from yawed traverses DO - 10.2514/6.2012-2670 AU - Brown, Anthony P. AU - Bastian, Matthew T2 - 4th AIAA Atmospheric and Space Environments Conference 2012 T3 - 4th AIAA Atmospheric and Space Environments Conference 2012, June 25-28, 2012, New Orleans, LA, USA SN - 9781624101922 SN - 978-1-62276-218-7 SP - 1 EP - 10 KW - Axial direction KW - Axial distance KW - Flight data KW - Flight research KW - Jet transports KW - Tertiary vortex KW - Vortex axis KW - Vortex cores KW - Flight paths KW - Wakes KW - Vortex flow AB - Over the period 2006 to 2012, the NRC enroute wake vortex flight research project has measured vortex core profiles and properties, during numerous traverses of the vortex cores generated by Heavy and Super Category jet transports, flying enroute in cruise. The vortex core traverses were conducted by the NRC T-33 and were all initiated in-trail, with the T-33 flight-path being parallel to the vortex core axis generally vortex core entries were made in the vortex core six o-clock position. Core traverses took 3/4 to 11/4 seconds, over which the T-33 flew along the vortex axis a distance of 200-300 metres, and 4-20 m across the cores, amounting to traverse angles of 2-4° The vortex core profile symmetry and/or constancy over such a small traverse angle was ascertained, by comparing the advancing and retreating segments (to the closest point-of-approach, CPA) of the profiles. Often the implied symmetry/constancy was good, sometimes it wasn't small, very energetic secondary and tertiary vortex segments were encountered only to or from the CPA, on either the advancing or retreating segment only. In particular, they made identification of vortex core funnel segments difficult. In 2011, yaw traverses of vortex cores were conducted, entering the cores at angles of yaw to the vortex axial direction, of 1530° and/or angles of pitch of c.5° so that the cores were traversed over much smaller axial distances than intrail traverses. The analyses of the flight data from these yaw core-traverses is presented. © 2012 by The Crown in Right of Canada. Published by the American Institute of Aeronautics and Astronautics, Inc. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ea28a2aa-44cd-4bb6-9b71-d4a18f130abe ER - TY - JOUR TI - On reducing low frequency impact sound transmission in wood framed construction AU - Zeitler, Berndt AU - Sabourin, Ivan AU - Schoenwald, Stefan AU - Wenzke, Erik T2 - 41st International Congress and Exposition on Noise Control Engineering 2012 (INTER-NOISE 2012) T3 - 41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012, August 19-22, 2012, New York, NY, USA SN - 9781627485609 VL - 8 SP - 6653 EP - 6662 KW - Code requirements KW - Direct impact KW - Impact sound KW - Impact sound transmissions KW - Parametric study KW - Acoustic wave transmission KW - Acoustic waves KW - Architectural acoustics KW - Design KW - Wooden construction AB - In an effort to generate design details for wood framed construction that meet the very stringent Korean Code requirements, solutions to reduce low frequency impact sound were developed. This paper presents these design details and the approach taken to develop them, which involved a parametric study of direct impact sound insulation followed by a flanking study. Results of the direct sound insulation study focus on the effects of topping and ceiling designs, whereas the flanking study focuses on the significance of flanking on the overall impact sound transmission between two rooms, one above the other, and on how a topping affects direct and flanking impact sound transmission differently. Copyright © (2012) by the Institute of Noise Control Engineering (INCE). DA - 2012 PY - 2012 PB - Curran Associates, Inc. LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 85c768c2-1dc0-44b9-9d3e-d3df3fbc7a6f ER - TY - JOUR TI - Classification and effect of floor treatment on wood frame construction AU - Zeitler, Berndt AU - Schoenwald, Stefan AU - King, Frances T2 - 41st International Congress and Exposition on Noise Control Engineering 2012 (INTER-NOISE 2012) T3 - 41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012, August 19-22, 2012, New York, NY, USA SN - 9781627485609 VL - 3 SP - 2346 EP - 2358 KW - Flanking sounds KW - Injected power KW - Sound transmission KW - Structure borne sound KW - Wood frame KW - Wood frame construction KW - Acoustic wave transmission KW - Architectural acoustics KW - Floors AB - Several recent NRC studies have investigated the change of sound insulation of lightweight framed floors, due to the addition of floor treatments (toppings and coverings). In this paper, a method to classify floor treatments as globally reacting or locally reacting is presented. A floor treatment that is locally reacting affects only the injected power and not the propagation of structure-borne sound to and through a junction. In this case, the floor treatment affects direct and all flanking sound transmission paths the same, for all path directions. A globally reacting floor treatment affects sound transmission in different paths differently, since it alters both the power injected, and the path itself. In this study lightweight wood frame floors were considered, where for globally reacting floor treatments, orientation of the floor treatment relative to the joists orientation are important parameters for their effectiveness. Several floor treatments (two toppings and six coverings) were measured and classified as locally or globally reacting, and effects are compared. Most of the floor treatments improved sound insulation, but two worsened it. DA - 2012 PY - 2012 PB - Curran Associates, Inc. LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6f26e91f-0fab-4301-8142-d5e2a4b64055 ER - TY - JOUR TI - Innovative moisture/icing-resistant flush air data system AU - Hui, Kenneth T2 - 28th Congress of the International Council of the Aeronautical Sciences 2012 (ICAS 2012) T3 - 28th Congress of the International Council of the Aeronautical Sciences 2012, ICAS 2012, September 23-28, 2012, Brisbane, Australia SN - 9781622767540 VL - 5 SP - 3669 EP - 3678 KW - Air data KW - Bombardier aerospaces KW - Calibration coefficients KW - Flush air data systems KW - Moisture condensation KW - National Research Council of Canada KW - Performance requirements KW - Simultaneous calibration KW - Angle of attack KW - Angle of attack indicators KW - Calibration KW - Meteorology KW - Moisture KW - Research laboratories KW - Aircraft AB - Bombardier Aerospace contracted the Flight Research Laboratory of the National Research Council of Canada (NRC) to develop a Flush Air Data System (FADS) capable of operation following transit through adverse weather conditions for use on Bombardier's test aircraft. The NRC's existing FADS design was modified to incorporate water traps at the inlet of each of the four pressure ports to prevent moisture ingestion into the pressure lines. A heating system was designed to reduce moisture condensation in the pressure lines. After fabrication of the final prototype was completed, experimental bench tests were performed to demonstrate that the FADS had met the performance requirements for flight through adverse conditions and that the system was safe for flight. The FADS was then sent to Bombardier Flight Test Centre and installed on a Bombardier Global 5000 aircraft for flight testing. To evaluate the FADS performance, manoeuvres were performed where the FADS was exposed to adverse weather conditions; the FADS angle of attack and angle of sideslip measurements were unaffected by these conditions during the tests. The FADS was calibrated using NRC's GPS-based Simultaneous Calibration of Air Data Systems (SCADS) technique by developing angle of attack and angle of sideslip calibration coefficients. The calibration coefficients were then validated across the aircraft's flight envelope and weather requirements. From the results of the bench tests and flight tests, it was concluded that the new FADS was able to measure angles of attack and sideslip after flight through adverse weather conditions accurately. © NRC Canada 2012. DA - 2012 PY - 2012 PB - Curran Associates, Inc. UR - http://www.icas.org/ICAS_ARCHIVE/ICAS2012/PAPERS/001.PDF LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c2462e31-0544-448c-b13b-c3ee615fe1af ER - TY - JOUR TI - Numerical simulations of self-sustained aeroelastic oscillations at low Reynolds numbers AU - Yuan, Weixing AU - Wang, Baoyuan AU - Poirel, Dominique T2 - 28th Congress of the International Council of the Aeronautical Sciences 2012 (ICAS 2012) T3 - 28th Congress of the International Council of the Aeronautical Sciences 2012, ICAS 2012, September 23-28, 2012, Brisbane, Australia SN - 9781622767540 VL - 1 SP - 816 EP - 825 KW - Aeroelastic oscillations KW - Degree of freedom KW - Limit cycle oscillations KW - Low Reynolds number KW - Low-Reaerodynamics KW - Self-sustained oscillations KW - Structural models KW - Two-degree-of-freedom KW - Aerodynamics KW - Airfoils KW - Computer simulation KW - Model structures KW - Reynolds number KW - Aeroelasticity AB - By coupling a two-degree-of-freedom structural model with an in-house incompressible code, numerical simulations were performed for a NACA 0012 airfoil undergoing self-sustained oscillations. As observed in experiments, the numerical simulations confirmed the presence of the pitch-heave limit-cycle oscillations of the airfoil at transitional Reynolds numbers, as a result of the nonlinear low-Re aerodynamics. The computed results revealed that the pitch motion of the pitch-heave limit-cycle oscillations at Rec < 80,000 was mainly maintained by the pitching moment feeding energy from the flow to the airfoil, while the pitch motion is believed to be sustained through the coupling with the second degree of freedom in heave at Rec > 80,000. Both pitch and heave motions were bounded by the pitching moment at ultimate pitch angles to a limit-cycle oscillation. DA - 2012 PY - 2012 PB - Curran Associates, Inc. UR - http://www.icas.org/ICAS_ARCHIVE/ICAS2012/PAPERS/159.PDF LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 207612ae-1b08-4e23-956e-e4ee8a6386a7 ER - TY - JOUR TI - Paraphrasing for style AU - Xu, Wei AU - Ritter, Alan AU - Dolan, William B. AU - Grishman, Ralph AU - Cherry, Colin T2 - COLING 2012, 24th International Conference on Computational Linguistics, Proceedings of the Conference: Technical Papers T3 - 24th International Conference on Computational Linguistics, COLING 2012, December 8-15, 2012, Mumbai, India SP - 2899 EP - 2914 KW - Automatic evaluation KW - Parallel text KW - Parallel training KW - Paraphrase KW - Shakespeare KW - Writing style KW - Computational linguistics AB - We present initial investigation into the task of paraphrasing language while targeting a particular writing style. The plays of William Shakespeare and their modern translations are used as a testbed for evaluating paraphrase systems targeting a specific style of writing. We show that even with a relatively small amount of parallel training data, it is possible to learn paraphrase models which capture stylistic phenomena, and these models outperform baselines based on dictionaries and out-of-domain parallel text. In addition we present an initial investigation into automatic evaluation metrics for paraphrasing writing style. To the best of our knowledge this is the first work to investigate the task of paraphrasing text with the goal of targeting a specific style of writing. © 2012 The COLING. DA - 2012 PY - 2012 UR - http://aclweb.org/anthology/C/C12/C12-1177.pdf LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0086e1ae-4352-4a54-9796-e5a56a246a74 ER - TY - JOUR TI - A benchmark analysis of Canadian clean technology commercialization accelerators AU - Malek, Kourosh AU - Maine, Elicia AU - McCarthy, Ian T2 - PICMET '12 : Portland International Center for Management of Engineering and Technology, proceedings, Technology Management for Emerging Technologies T3 - 2012 Portland International Conference on Management of Engineering and Technology - Technology Management for Emerging Technologies, PICMET'12, July 29 - August 2, 2012, Vancouver, BC, Canada SN - 1890843261 SN - 9781890843267 SP - 6304101 SP - 836 EP - 845 KW - Applied research KW - Benchmark analysis KW - Business models KW - Business practices KW - Clean energy KW - Clean energy technology KW - Clean technologies KW - Direct product KW - Governance structures KW - In-depth analysis KW - Management practices KW - Non profit organizations KW - Non-profit KW - Operational model KW - Strategic partnership KW - Strategic plan KW - Technology commercializations KW - Technology-based KW - University research KW - Commerce KW - Industrial management KW - Profitability KW - Societies and institutions KW - Technology AB - Although the size of the Canadian clean energy market is small, high R&D capacity and clean-tech ventures delivering emerging clean energy technologies could potentially make Canada a global leader in supplying direct products, services and infrastructure to clean energy markets. Technology commercialization centres are of vital importance in facilitating and accelerating the transfer of academic and applied research to create and support technology-based ventures. However, there is a lack of clarity around the governance, performance, operation, and business model of such organizations. In order to develop and implement the best business practices for Clean Energy Commercialization Accelerators (CECAs), this paper explores different business operational models which were adopted by different non-profit clean energy commercialization organizations. A two-stage approach was employed. In the first stage, over fifteen organizations (including twelve non-profit organizations and three university research parks) in Canada, the U.S., and Europe were selected for benchmark analysis. Four distinct business operational models emerge based upon an in-depth analysis: incubation focused, technology-enabled, market-enabled, and strategic partnership. Thereafter, a typology of organizations is proposed, based on four discriminating models: governance, finance, operation, and revenue. This typological analysis is then employed to unravel best business practices for CECAs, in view of governance structure, management practice, community impacts, overall business model and performance, strategic plan, and operation. © 2012 IEEE.. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f426f91b-4768-4bb9-b9ac-fc2424643bf8 ER - TY - JOUR TI - Ecological validity and the evaluation of speech summarization quality DO - 10.1109/SLT.2012.6424269 AU - McCallum, Anthony AU - Penn, Gerald AU - Munteanu, Cosmin AU - Zhu, Xiaodan T2 - Spoken Language Technology Workshop (SLT), 2012 IEEE T3 - 2012 IEEE Workshop on Spoken Language Technology, SLT 2012, December 2-5, 2012, Miami, FL, USA SN - 978-1-4673-5125-6 SN - 978-1-4673-5124-9 SP - 6424269 SP - 467 EP - 472 KW - Automatically generated KW - Ecological validity KW - Evaluation criteria KW - Evaluation measures KW - Evaluation protocol KW - Goal orientations KW - Gold standards KW - Human-centric KW - NAtural language processing KW - Natural languages KW - Reference data KW - Speech summarization KW - Summarization systems KW - Gold KW - Human computer interaction KW - Natural language processing systems KW - Speech analysis KW - Speech recognition KW - Quality control AB - There is little evidence of widespread adoption of speech summarization systems. This may be due in part to the fact that the natural language heuristics used to generate summaries are often optimized with respect to a class of evaluation measures that, while computationally and experimentally inexpensive, rely on subjectively selected gold standards against which automatically generated summaries are scored. This evaluation protocol does not take into account the usefulness of a summary in assisting the listener in achieving his or her goal. In this paper we study how current measures and methods for evaluating summarization systems compare to human-centric evaluation criteria. For this, we have designed and conducted an ecologically valid evaluation that determines the value of a summary when embedded in a task, rather than how closely a summary resembles a gold standard. The results of our evaluation demonstrate that in the domain of lecture summarization, the well-known baseline of maximal marginal relevance [1] is statistically significantly worse than human-generated extractive summaries, and even worse than having no summary at all in a simple quiz-taking task. Priming seems to have no statistically significant effect on the usefulness of the human summaries. This is interesting because priming had been proposed as a technique for increasing kappa scores and/or maintaining goal orientation among summary authors. In addition, our results suggest that ROUGE scores, regardless of whether they are derived from numerically-ranked reference data or ecologically valid human-extracted summaries, may not always be reliable as inexpensive proxies for task-embedded evaluations. In fact, under some conditions, relying exclusively on ROUGE may lead to scoring human-generated summaries very favourably even when a task-embedded score calls their usefulness into question relative to using no summaries at all. © 2012 IEEE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e02c6836-327e-4030-8d89-96d3ef98cd39 ER - TY - JOUR TI - 25Mg Solid-state NMR: A sensitive probe of adsorbing guest molecules on a metal center in metal-organic framework CPO-27-Mg DO - 10.1021/jz301954t AU - Xu, Jun AU - Terskikh, Victor V. AU - Huang, Yining T2 - The Journal of Physical Chemistry Letters SN - 1948-7185 VL - 4 IS - 1 SP - 7 EP - 11 KW - Adsorption ability KW - Adsorption capability KW - Adsorptive properties KW - Desolvation KW - Direct interactions KW - Guest molecules KW - Guest species KW - Host guest interactions KW - Local environments KW - Metal centers KW - Metal organic framework KW - Natural abundance KW - Powder XRD KW - Sensitive probe KW - Solid state NMR KW - Solvent molecules KW - Ultra-high magnetic fields KW - XRD KW - Adsorption KW - Crystalline materials KW - Java programming language KW - Solid state physics KW - Nuclear magnetic resonance spectroscopy AB - Metal-organic frameworks (MOFs) have excellent adsorption capability. To understand their adsorptive properties requires detailed information on the host-guest interaction. The information on MOF desolvation (or activation) is also crucial because the very first step of many applications requires removal of the solvent molecules occluded inside of the pores. Unfortunately, such information is not always available from powder XRD data. Solid-state NMR is an excellent complementary technique to XRD. CPO-27-Mg is a MOF with unusual adsorption ability. The adsorption involves a direct interaction between Mg and guest species. Herein, we present, for the first time, a natural abundance 25Mg solid-state NMR study of CPO-27-Mg at an ultrahigh magnetic field of 21.1 T. The results provide new physical insights into the effects of dehydration/rehydration and adsorption of guest species on the Mg local environment. DA - 2012/12/07 PY - 2012 PB - ACS Publishing LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e47632d0-f50a-40fe-9d64-8113b2b19323 ER - TY - JOUR TI - The horizontal branch of NGC1851: constraints from its RR Lyrae variables DO - 10.1088/0004-6256/145/1/25 AU - Kunder, Andrea AU - Salaris, Maurizio AU - Cassisi, Santi AU - De Propris, Roberto AU - Walker, Alistair AU - Stetson, Peter B. AU - Catelan, Márcio AU - Amigo, Pía T2 - Astronomical Journal SN - 0004-6256 VL - 145 IS - 1 SP - 25 AB - We use the pulsational properties of the RR Lyrae variables in the globular cluster NGC1851 to obtain detailed constraints of the various sub-stellar populations present along its horizontal branch. On the basis of detailed synthetic horizontal branch modeling, we find that minor helium variations (Y ∼ 0.248-0.280) are able to reproduce the observed periods and amplitudes of the RR Lyrae variables, as well as the frequency of fundamental and first-overtone RR Lyrae stars. Comparison of number ratios among the blue and red horizontal branch components and the two observed subgiant branches also suggest that the RR Lyrae variables originated from the progeny of the bright subgiant branch. The RR Lyrae variables with slightly enhanced helium (Y ∼ 0.270-0.280) have longer periods at a given amplitude, as is seen with Oosterhoff II (OoII) RR Lyrae variables, whereas the RRLyrae variables with Y ∼ 0.248-0.270 have shorter periods, exhibiting properties of Oosterhoff I (OoI) variables. This correlation does suggest that the pulsational properties of RR Lyrae stars can be very useful for tracing the various subpopulations and can provide suitable constraints on the multiple population phenomenon. It appears to be of great interest to explore whether this conclusion can be generalized to other globular clusters hosting multiple populations. DA - 2012/12/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e9ef8246-0c10-45b1-a809-0a4b590c3ccb ER - TY - JOUR TI - Entangling the motion of diamonds at room temperature DO - 10.1364/QELS.2012.QM3C.6 AU - Sprague, Michael R. AU - Lee, K. C. AU - Sussman, Ben J. AU - Nunn, Josh AU - Langford, Nathan K. AU - Jin, Xian-Min AU - Champion, Tessa AU - Michelberger, Patrick AU - Reim, Klaus F. AU - England, Duncan G. AU - Jaksch, Dieter AU - Walmsley, Ian A. T2 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012 T3 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012, May 6-11, 2012, San Jose, CA, USA SN - 9781467318396 SP - 6326899 KW - Raman interactions KW - Room temperature KW - Vibrational modes KW - Lasers AB - We demonstrate entanglement between the vibrational mode of two macroscopic, spatially-separated diamonds at room temperature with ultrashort pulses and a far-off-resonant Raman interaction. © 2012 OSA. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 93590704-eb70-43da-8fb2-c4c1b533a77d ER - TY - JOUR TI - BSA nanoparticles for siRNA delivery: Coating effects on nanoparticle properties, plasma protein adsorption, and in vitro siRNA delivery DO - 10.1155/2012/584060 AU - Yogasundaram, H. AU - Bahniuk, M.S. AU - Singh, H.-D. AU - Aliabadi, H.M. AU - Uludaǧ, H. AU - Unsworth, L.D. T2 - International Journal of Biomaterials SN - 1687-8787 SP - 584060 AB - Developing vehicles for the delivery of therapeutic molecules, like siRNA, is an area of active research. Nanoparticles composed of bovine serum albumin, stabilized via the adsorption of poly-L-lysine (PLL), have been shown to be potentially inert drug-delivery vehicles. With the primary goal of reducing nonspecific protein adsorption, the effect of using comb-type structures of poly(ethylene glycol) (1 kDa, PEG) units conjugated to PLL (4.2 and 24 kDa) on BSA-NP properties, apparent siRNA release rate, cell viability, and cell uptake were evaluated. PEGylated PLL coatings resulted in NPs with ζ-potentials close to neutral. Incubation with platelet-poor plasma showed the composition of the adsorbed proteome was similar for all systems. siRNA was effectively encapsulated and released in a sustained manner from all NPs. With 4.2 kDa PLL, cellular uptake was not affected by the presence of PEG, but PEG coating inhibited uptake with 24 kDa PLL NPs. Moreover, 24 kDa PLL systems were cytotoxic and this cytotoxicity was diminished upon PEG incorporation. The overall results identified a BSA-NP coating structure that provided effective siRNA encapsulation while reducing ζ-potential, protein adsorption, and cytotoxicity, necessary attributes for in vivo application of drug-delivery vehicles. Copyright © 2012 Haran Yogasundaram et al. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4fdc1201-199b-455e-94b5-f1d1dc1f2451 ER - TY - JOUR TI - Powder processing and coating heat treatment on cold sprayed Ti-6Al-4V alloy DO - 10.4028/www.scientific.net/MSF.706-709.258 AU - Wong, W. AU - Irissou, E. AU - Legoux, J.G. AU - Vo, P. AU - Yue, S. T2 - Materials Science Forum T3 - 7th International Conference on Processing and Manufacturing of Advanced Materials, THERMEC'2011, 1 August 2011 through 5 August 2011, Quebec City, QC SN - 0255-5476 SN - 9783037853030 VL - 706-709 SP - 258 EP - 263 KW - Argon atmospheres KW - Ball-milled KW - Coating deposition KW - Coating hardness KW - Coating porosity KW - Cohesion strength KW - Cold spray KW - Feedstock powders KW - Heat treatment temperature KW - Low energies KW - Micro tensile tests KW - Nitrogen gas KW - Particle impact velocities KW - Powder flowability KW - Powder processing KW - Propellant gas KW - Static recovery KW - Ti-6al-4v KW - Ti-6Al-4V alloy KW - Aluminum KW - Argon KW - Cerium alloys KW - Heat treatment KW - Mechanical properties KW - Nitrogen KW - Powder coatings KW - Sintering KW - Sprayed coatings KW - Tensile strength KW - Tensile testing KW - Titanium alloys KW - Vanadium KW - Vanadium alloys KW - Aluminum coatings AB - This study investigates the effect of powder processing on powder flowability, compact ability, and the heat treatment of the resulting coatings on the mechanical properties of cold gas dynamic sprayed Ti-6Al-4V alloy. Nitrogen gas was used throughout the coating deposition process. Propellant gas temperature and pressure were attuned to maximize particle impact velocity. Three powder processing conditions were used in this study: as received (AR), low-energy ball milled (BM), and argon atmosphere heat treated (HT). Results showed coating porosities of around 6 to 7%, regardless of the feedstock powder used or the heat treatment performed. It was observed at 600 and 800°C anneals that a coating hardness reduction occurred, possibly due to static recovery and recrystallization, with minor sintering possibly occurring at the 800°C anneals. In addition, micro tensile tests showed an increase in cohesion strength at higher heat treatment temperatures. © 2012 Trans Tech Publications, Switzerland. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 45202140-473b-4a2b-9415-6d0eeda5d5fe ER - TY - JOUR TI - How starless are starless cores? DO - 10.1088/0004-637X/745/1/18 AU - Schnee, S. AU - Di Francesco, J. AU - Enoch, M. AU - Friesen, R. AU - Johnstone, D. AU - Sadavoy, S. T2 - The Astrophysical Journal SN - 0004-637X VL - 745 IS - 1 SP - 18 AB - In this paper, we present the results of Combined Array for Research in Millimeter-wave Astronomy continuum and spectral line observations of the dense core Per-Bolo 45. Although this core has previously been classified as starless, we find evidence for an outflow and conclude that Per-Bolo 45 is actually an embedded, low-luminosity protostar. We discuss the impact of newly discovered, low-luminosity, embedded objects in the Perseus molecular cloud on starless core and protostar lifetimes. We estimate that the starless core lifetime has been overestimated by 4%-18% and the Class 0/I protostellar lifetime has been underestimated by 5%-20%. Given the relatively large systematic uncertainties involved in these calculations, variations on the order of 10% do not significantly change either core lifetimes or the expected protostellar luminosity function. Finally, we suggest that high-resolution (sub)millimeter surveys of known cores lacking near-infrared and mid-infrared emission are necessary to make an accurate census of starless cores. © 2012. The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 71661bf4-bf06-4104-ad31-783d84c090a7 ER - TY - JOUR TI - Initial conditions for star formation in clusters: Physical and kinematical structure of the starless core Oph A-N6 DO - 10.1088/0004-637X/745/2/117 AU - Bourke, T.L. AU - Myers, P.C. AU - Caselli, P. AU - Di Francesco, J. AU - Belloche, A. AU - Plume, R. AU - Wilner, D.J. T2 - The Astrophysical Journal SN - 0004-637X VL - 745 IS - 2 SP - 117 AB - We present high spatial (<300AU) and spectral (0.07kms -1) resolution Submillimeter Array observations of the dense starless cluster core Oph A-N6 in the 1mm dust continuum and the 3-2 line of N 2H + and N 2D +. The dust continuum observations reveal a compact source not seen in single-dish observations, of size 1000AU and mass 0.005-0.01 M. The combined line and single-dish observations reveal a core of size 3000 × 1400AU elongated in a NW-SE direction, with almost no variation in either line width nor line center velocity across the map, and very small non-thermal motions. The deuterium fraction has a peak value of 0.15 and is >0.05 over much of the core. The N 2H + column density profile across the major axis of Oph A-N6 is well represented by an isothermal cylinder, with temperature 20K, peak density 7.1 × 10 6cm -3, and N 2H + abundance 2.7 × 10 -10. The mass of Oph A-N6 is estimated to be 0.29 M , compared to a value of 0.18 M from the isothermal cylinder analysis, and 0.63 M for the critical mass for fragmentation of an isothermal cylinder. Compared to isolated low-mass cores, Oph A-N6 shows similar narrow line widths and small velocity variation, with a deuterium fraction similar to "evolved" dense cores. It is significantly smaller than isolated cores, with larger peak column and volume density. The available evidence suggests that Oph A-N6 has formed through the fragmentation of the Oph A filament and is the precursor to a low-mass star. The dust continuum emission suggests that it may already have begun to form a star. © 2012. The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 27849ac0-6d35-4bf0-af83-45c04c9371dc ER - TY - CHAP TI - On Liquation and Liquid Phase Oxidation during Linear Friction Welding of Nickel-Base IN738 and CMSX Superalloys DO - 10.1002/9781118516430.ch65 AU - Amegadzie, M.Y. AU - Ola, O.T. AU - Ojo, O.A. AU - Wanjara, P. AU - Chaturvedi, M.C. T2 - Superalloys 2012 SN - 9780470943205 SP - 587 EP - 594 AB - A systematic study of the microstructural response of conventionally cast IN 738 and single crystal CMSX 486 superalloys during linear friction welding was performed. The results revealed that, aside from a significant liquation of various phases that occurred during joining, continuous oxide films formed on the weld lines in both materials. The weld line oxides consisted of aluminum-rich and hafnium-base oxides in IN 738 and CMSX 486 superalloys, respectively, which can be deleterious to the mechanical properties of the weld joint. Gleeble thermo-mechanical simulation showed that the oxides were produced by the oxidation of some liquid exposed to atmospheric oxygen at the mating surfaces of the work pieces. A practicable method of eliminating liquid phase oxidation during linear friction welding of nickel-base superalloys is discussed. © 2012 The Minerals, Metals, & Materials Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d581a09e-18e3-4b44-866d-d8a09d783f2f ER - TY - JOUR TI - POEs for green buildings AU - Birt, B.J. AU - Newsham, G.R. AU - Veitch, J.A. AU - Arsenault, C. T2 - Lighting Design and Application: LD and A SN - 0360-6325 VL - 42 IS - 4 SP - 70 EP - 72 DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 099c020e-8701-4be8-b434-4226bfd6ffa6 ER - TY - JOUR TI - Neutron diffraction analysis of phase precipitation in solidification of hypereutectic Al-Si alloys with the addition of Cu and Mg DO - 10.1002/9781118359259.ch60 AU - Sediako, D. AU - Kasprzak, W. T2 - TMS Light Metals T3 - Light Metals 2012 - TMS 2012 Annual Meeting and Exhibition, 11 March 2012 through 15 March 2012, Orlando, FL SN - 0147-0809 SN - 9781118291399 SP - 355 EP - 364 KW - Alloying additions KW - As cast microstructure KW - FactSage KW - Hypereutectic Al-Si alloys KW - Hypereutectic aluminum-silicon alloys KW - Industrial alloys KW - Key factors KW - Neutron diffraction analysis KW - Phase precipitations KW - Service properties KW - Si alloys KW - Solid phasis KW - Solid-phase KW - Solidification kinetics KW - Solidification process KW - Thermodynamic calculations KW - Aluminum KW - Aluminum alloys KW - Binary alloys KW - Exhibitions KW - Kinetics KW - Neutron diffraction KW - Precipitation (chemical) KW - Silicon KW - Silicon alloys KW - Thermoanalysis KW - Solidification AB - A good understanding of the kinetics of evolution of solid phases during solidification of hypereutectic aluminum alloys is a key factor in controlling the as-cast microstructure and, in turn, enhancing the service properties of industrial alloys. A study was performed to evaluate the solidification kinetics for two hypereutectic Al-19%Si alloys with the addition of 3%Cu and 3%Cu+1%Mg. This study included thermodynamic calculations of the solidification process using the FactSage™ 6.2 software package, as well as experimental thermal analysis, and neutron diffraction. The study revealed kinetics of solid Al, solid Si, Al 2CU, and Mg 2Si evolution, as well as an individual effect of Cu and Mg alloying additions on the solidification path of the Al-Si system. DA - 2012/05/03 PY - 2012 PB - Minerals, Metals and Materials Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : aabf0615-8256-4d14-85f5-b38567b4c3d4 ER - TY - JOUR TI - Microstructures, mechanical properties, and erosion resistance of unbalanced magnetron sputtering deposited TiN/VN nano-structured coatings DO - 10.1007/s13632-012-0025-9 AU - Yang, Q. AU - Bielawski, M. AU - McKellar, R.C. T2 - Metallography, Microstructure, and Analysis SN - 2192-9262 VL - 1 IS - 3-Apr SP - 150 EP - 157 KW - Aerospace KW - Bi-layer KW - Erosion resistance KW - Ion fluxes KW - Microstructures and properties KW - Nano-structured KW - Nanostructured coatings KW - Non-ferromagnetic KW - Pole figure KW - Preferred orientations KW - Substrate material KW - Substrate types KW - Surface engineering KW - Ti-6al-4v KW - Ti-6al-4v titanium alloys KW - Unbalanced magnetron sputtering KW - XRD measurements KW - Young's Modulus KW - Aluminum coatings KW - Coatings KW - Deposits KW - Dissimilar materials KW - Elastic moduli KW - Erosion KW - Ferromagnetic materials KW - Ferromagnetism KW - Indentation KW - Magnetic properties KW - Microstructure KW - Titanium alloys KW - Tribology KW - Substrates AB - Nano-structured TiN/VN coatings with a range of bi-layer periods from 3. 4 to 11. 0 nm were deposited on ferromagnetic 410 stainless steel (410SS) and non-ferromagnetic Ti-6Al-4V titanium alloy substrates using an Unbalanced Magnetron Sputtering (UMS) technique; the microstructure, mechanical properties, and erosion performance of the as-sputtered coating were evaluated. While the surface morphologies of the coatings on these two substrates were different, the XRD measurements complemented by a texture evaluation through pole figures indicated that the preferred orientations of the TiN/VN coatings on 410SS and Ti-6Al-4V were also dissimilar. A nano-mechanical indentation technique was used to determine hardness and Young's modulus, and it was found that these parameters varied with superlattice bi-layer period and were dependent on the type of substrate material. Furthermore, the erosion resistances of the TiN/VN coatings were markedly higher than the bare substrate counterparts, and were influenced by the substrate type. Specifically, the differences in the microstructures and properties of the coatings were attributed to the difference in ion flux during the UMS deposition due to the dissimilar magnetic properties of the substrate materials. © 2012 Springer Science+Business Media, LLC and ASM International. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cead1f35-7402-42bc-8020-e10830ea1083 ER - TY - JOUR TI - Cell surface glycoproteins from Thermoplasma acidophilum are modified with an N-linked glycan containing 6-C-sulfofucose DO - 10.1093/glycob/cws094 AU - Vinogradov, E. AU - Deschatelets, L. AU - Lamoureux, M. AU - Patel, G.B. AU - Tremblay, T.-L. AU - Robotham, A. AU - Goneau, M.-F. AU - Cummings-Lorbetskie, C. AU - Watson, D.C. AU - Brisson, J.-R. AU - Kelly, J.F. AU - Gilbert, M. T2 - Glycobiology SN - 0959-6658 VL - 22 IS - 9 SP - 1256 EP - 1267 KW - Thermoplasma; glycoprotein; N-linked glycan; sulfofucose AB - Thermoplasma acidophilum is a thermoacidophilic archaeon that grows optimally at pH 2 and 59°C. This extremophile is remarkable by the absence of a cell wall or an S-layer. Treating the cells with Triton X-100 at pH 3 allowed the extraction of all of the cell surface glycoproteins while keeping cells intact. The extracted glycoproteins were partially purified by cation-exchange chromatography, and we identified five glycoproteins by N-terminal sequencing and mass spectrometry of in-gel tryptic digests. These glycoproteins are positive for periodic acid-Schiff staining, have a high content of Asn including a large number in the Asn-X-Ser/Thr sequon and have apparent masses that are 34-48 larger than the masses deduced from their amino acid sequences. The pooled glycoproteins were digested with proteinase K and the purified glycopeptides were analyzed by NMR. Structural determination showed that the carbohydrate part was represented by two structures in nearly equal amounts, differing by the presence of one terminal mannose residue. The larger glycan chain consists of eight residues: six hexoses, one heptose and one sugar with an unusual residue mass of 226 Da which was identified as 6-deoxy-6-C-sulfo-d-galactose (6-C-sulfo-d-fucose). Mass spectrometry analyses of the peptides obtained by trypsin and chymotrypsin digestion confirmed the principal structures to be those determined by NMR and identified 14 glycopeptides derived from the main glycoprotein, Ta0280, all containing the Asn-X-Ser/Thr sequons. Thermoplasma acidophilum appears to have a "general" protein N-glycosylation system that targets a number of cell surface proteins. © 2012 The Author. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3fe82e65-84d2-4766-9a49-f2b982e42423 ER - TY - JOUR TI - Selecting the polarization in silicon photonic wire components DO - 10.1117/12.911368 AU - Xu, Dan-Xia AU - Delâge, André AU - Schmid, Jens H. AU - Ma, Rubin AU - Wang, Shurui AU - Lapointe, Jean AU - Vachon, Martin AU - Cheben, Pavel AU - Janz, Siegfried T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Silicon Photonics VII, 22 January 2012 through 25 January 2012, San Francisco, CA SN - 0277-786X SN - 9780819489098 VL - 8266 SP - 82660G KW - Polarization conversion KW - Polarization diversity KW - Polarization independence KW - Ring resonator KW - Silicon photonics KW - Birefringence KW - Directional couplers KW - Optical waveguides KW - Photonic devices KW - Waveguides KW - Polarization AB - Silicon photonic wire waveguides are usually highly birefringent, so they are generally designed to operate for one particular polarization. For commonly used waveguides with a silicon thickness of 220 nm, TE polarization is preferred since TM is only weakly guided. For waveguides with a silicon thickness larger than 250 nm, both TE and TM polarizations have been employed. Overall, the choice of polarization has largely appeared arbitrary. In this presentation we review the pertinent polarization-dependent waveguide properties, including losses, back-reflection, polarization conversion and fabrication tolerances, with the intent to suggest guidelines for choosing the proper polarization. Through experimental evidence, we show that TM polarization has several important advantages and can support high performance resonators with a radius down to 2 μm. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3b939b0e-9e10-4357-9c76-b333d05bdc60 ER - TY - JOUR TI - A comparison of the mechanical design of fiber feeds for GRACES and GHOS DO - 10.1117/12.927210 AU - Anthony, A. AU - Hill, A. AU - Pazder, J. AU - Szeto, K. AU - Halman, M. AU - Tollestrup, E. AU - Barrick, G. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Ground-Based and Airborne Instrumentation for Astronomy IV, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491473 VL - 8446 SP - 84464A KW - Design solutions KW - Focal ratio degradation KW - Gemini telescopes KW - High resolution KW - Mechanical design KW - Optical spectrograph KW - Remote access KW - Astrophysics KW - Conceptual design KW - Optical telescopes KW - Optics KW - Spectrographs KW - Telescopes KW - Fibers AB - The instrument group of the Herzberg Institute of Astrophysics has been commissioned by the Gemini Observatory to participate in a competitive conceptual design study for a new Gemini High-Resolution Optical Spectrograph (GHOS). Concurrently this same group is working in partnership with both the Gemini and CFH Telescopes to design the Gemini Remote Access to CFHT ESPaDOnS Spectrograph, (GRACES). Both these instruments will use a fiber feed allowing light received by the Gemini telescope to be processed via remotely positioned instruments. This paper will explore the similarities and differences in requirements, inherent challenges, concepts, design solutions and areas of concept sharing. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 06c5613f-1701-4c8a-8db8-06924e25be09 ER - TY - JOUR TI - Self-induced thermal nonlinearities in InGaAsP microtubes at telecom wavelengths AU - Tian, Z. AU - Bianucci, P. AU - Dastjerdi, M.H.T. AU - Mi, Z. AU - Poole, P.J. AU - Plant, D.V. T2 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012 T3 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012, 6 May 2012 through 11 May 2012, San Jose, CA SN - 9781467318396 SP - 6326069 KW - Active application KW - InGaAsP KW - Micro-tubes KW - Resonance wavelengths KW - Telecom wavelengths KW - Thermal nonlinearities KW - Lasers AB - We demonstrate, for the first time, dynamical thermal effects in InGaAsP microtubes at telecom wavelengths. Such effect can be avoided or exploited for passive or active applications by choosing appropriate resonance wavelengths. © 2012 OSA. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 12a2f932-16ad-45eb-975a-de3e674043ee ER - TY - JOUR TI - Probing the experimental phonon dispersion of graphene using 12C and 13C isotopes DO - 10.1103/PhysRevB.86.085409 AU - Bernard, S. AU - Whiteway, E. AU - Yu, V. AU - Austing, D.G. AU - Hilke, M. T2 - Physical Review B - Condensed Matter and Materials Physics SN - 1098-0121 VL - 86 IS - 8 SP - 85409 AB - Using very uniform large-scale chemical vapor deposition grown graphene transferred onto silicon, we were able to identify 15 distinct Raman lines associated with graphene monolayers. This was possible thanks to a combination of different carbon isotopes and different Raman laser energies and extensive averaging without increasing the laser power. This allowed us to obtain a detailed experimental phonon dispersion relation for many points in the Brillouin zone. We further identified a D+D′ peak corresponding to a double-phonon process involving both an inter- and intravalley phonon. © 2012 American Physical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e90b058a-77d4-4808-9c30-d4b7a67bf11b ER - TY - JOUR TI - Band engineering in nanowires: Ab initio model of band edges modified by (111) biaxial strain in group IIIA-VA semiconductors DO - 10.1103/PhysRevB.86.085411 AU - Kadantsev, E.S. AU - Zieliński, M. AU - Hawrylak, P. T2 - Physical Review B - Condensed Matter and Materials Physics SN - 1098-0121 VL - 86 IS - 8 SP - 85411 AB - Quantum dots in nanowires grow on a (111) substrate and it is expected that the modifications of the band structure due to a biaxial strain in the (111) crystallographic plane will determine the confinement of charge carriers in these systems. In this work, we develop an ab initio methodology for the determination of biaxial strain-modified band energies on an absolute energy scale due to a strain in an arbitrary crystallographic plane and apply it to calculate the evolution of band edges in group IIIA-VA zinc-blende semiconductors (InP, InAs, and GaAs) under the (111) biaxial strain. The absolute hydrostatic deformation potentials, a prerequisite for the accurate calculation of the strain-modified band energies within our scheme, are determined. The strain tensor for an InAs dot grown on a (111) GaAs substrate is calculated and the importance of the (111) biaxial strain is demonstrated. The strained band offsets in InAs under a compressive biaxial strain in the (001) and (111) crystallographic planes as well as the local band structure in a InAs/GaAs dot indicates a stronger confinement of holes in the (111) case. ©2012 American Physical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 69ed6d8c-a8b8-4452-af3c-1d31d6e9c594 ER - TY - JOUR TI - Stable expression of chimeric heavy chain antibodies in CHO cells DO - 10.1007/978-1-61779-968-6-18 AU - Agrawal, V. AU - Slivac, I. AU - Perret, S. AU - Bisson, L. AU - St-Laurent, G. AU - Murad, Y. AU - Zhang, J. AU - Durocher, Y. T2 - Methods in Molecular Biology SN - 1064-3745 SN - 9781617799679 VL - 911 SP - 287 EP - 303 KW - antibiotic g 418 KW - blasticidin S KW - chimeric antibody KW - chimeric heavy chain antibody KW - hygromycin B KW - phleomycin KW - plasmid vector KW - polyethyleneimine KW - puromycin KW - unclassified drug KW - hybrid protein KW - immunoglobulin heavy chain KW - monoclonal antibody KW - animal cell KW - antibody production KW - article KW - CHO cell KW - cloning KW - controlled study KW - culture technique KW - drug activity KW - genetic transfection KW - heavy chain KW - nonhuman KW - priority journal KW - protein expression KW - suspension cell culture KW - toxicity KW - animal KW - gene expression KW - gene order KW - gene vector KW - genetics KW - hamster KW - isolation and purification KW - metabolism KW - Animals KW - Antibodies, Monoclonal KW - CHO Cells KW - Cricetinae KW - Gene Expression KW - Gene Order KW - Genetic Vectors KW - Immunoglobulin Heavy Chains KW - Recombinant Fusion Proteins KW - Transfection AB - Camelid single domain antibodies fused to noncamelid Fc regions, also called chimeric heavy chain antibodies (cHCAb), offer great potential as therapeutic and diagnostic candidates due to their relatively small size (80 kDa) and intact Fc. In this chapter, we describe two approaches, limiting dilution and minipools, for generating nonamplified Chinese hamster ovary cell lines stably expressing cHCAb in suspension and serum-free cultures using a stringent antibiotic selection. Neither of the protocols necessitates the acquisition or implementation of expensive automated infrastructures and thus could be applied in any lab with minimal cell culture setup. The given protocol allows the isolation of stable clones capable of generating up to 100 mg/L of antibody in batch mode performed in shaker flasks. © 2012 Springer Science+Business Media, LLC. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3b08d77b-835e-464b-8195-def3eef78cf8 ER - TY - JOUR TI - Sr+88 445-THz single-ion reference at the 10 -17 level via control and cancellation of systematic uncertainties and its measurement against the SI second DO - 10.1103/PhysRevLett.109.203002 AU - Madej, Alan A. AU - Dubé, Pierre AU - Zhou, Zichao AU - Bernard, John E. AU - Gertsvolf, Marina T2 - Physical Review Letters SN - 0031-9007 VL - 109 IS - 20 SP - 203002 KW - Absolute frequency measurements KW - Center frequency KW - Ion transition KW - Laser-cooled KW - Optical frequency standard KW - Polarizabilities KW - Single ion KW - Strontium ion KW - Systematic uncertainties KW - Time transfer KW - Frequency standards KW - Ions KW - Strontium KW - Uncertainty analysis AB - We describe experiments and measurements on a trapped and laser-cooled single ion of Sr+88 which, when probed on its reference 5sS1/22→4dD5/22 transition at 445THz, provides an optical frequency standard of evaluated accuracy outperforming the current realization of the SI second. Studies are presented showing that micromotion-associated shifts of the standard can be reduced to the 10 -18 level and uncertainties in the blackbody-induced shifts for the current system are at the low 10 -17 level due to the relatively well-known polarizability of the strontium ion system and careful choice of the trap structure. The current evaluated systematic shifts for the ion transition are at a fractional uncertainty of 2×10 -17. An absolute frequency measurement performed over a two-month period relative to a maser referenced to the SI second via Global Positioning System time transfer has determined the center frequency for the transition at ν SD= 444779044095485.5±0.9Hz (1σ). DA - 2012/11/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 274298e0-fe5e-48f5-8e2a-99255f633147 ER - TY - JOUR TI - High speed routing of woven carbon fiber reinforced epoxy laminates DO - 10.1115/IMECE2012-88616 AU - Meshreki, M. AU - Sadek, A. AU - Attia, M.H. T2 - ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) T3 - ASME 2012 International Mechanical Engineering Congress and Exposition, IMECE 2012, 9 November 2012 through 15 November 2012, Houston, TX SN - 9780791845196 VL - 3 IS - PARTS A, B and C SP - 2061 EP - 2066 KW - Carbon fiber reinforced KW - Carbon fiber reinforced polymer KW - Quality attributes KW - Quasiisotropic laminates KW - Specific cutting pressure KW - Straightness errors KW - Temperature trends KW - Thermal characteristics KW - Carbon fiber reinforced plastics KW - Delamination KW - Errors KW - Laminates KW - Mechanical engineering KW - Milling (machining) KW - Quality control KW - Surface roughness KW - Tools KW - Wear of materials KW - Weaving KW - Speed AB - Little is known about the high speed routing of Carbon Fiber Reinforced Polymers (CFRP). Most of the work in the literature has focused on the drilling of CFRP. In this paper, an extensive experimental study has been conducted to better understand the dynamic, tribological, and thermal characteristics of high speed milling of CFRPs, in the range of 10,000 to 40,000 rpm (200 to 800 m/min, for 6.35 mm end-mill). The material used was a quasi-isotropic laminate comprising 35 plies of woven graphite epoxy. The tool wear was investigated on the flank and the rake faces. The machined slots were characterized in terms of straightness errors, dimensional errors, surface roughness, and delamination. The tool over-hang controls the tool dynamics, in this high speed range, and significantly affect various quality attributes of the produced holes; roughness, dimensional errors, and straightness. Similar trends were observed for the forces and the temperatures, whereby there is a given speed at which they reach a minimum and then they start to increase for higher speeds. The machining force and temperature trends with varying speeds and feeds are controlled by the chip load, the specific cutting pressures, and the effect of the frictional forces. The increased tool wear was found to directly affect the cutting forces and consequently lead to high delamination and surface roughness. The milled surface quality was mainly controlled by the feed rate. Limited surface delamination was observed due to the low axial forces associated with the routing process. Copyright © 2012 by ASME. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 15cff071-56a1-4528-8931-1ddaa81ff8bc ER - TY - JOUR TI - Perforated metal sheets as gas diffusion layers for proton exchange membrane fuel cells DO - 10.1149/2.017203esl AU - Blanco, M. AU - Wilkinson, D.P. AU - Wang, H. T2 - Electrochemical and Solid-State Letters SN - 1099-0062 VL - 15 IS - 3 SP - B20 EP - B23 KW - Base-line performance KW - Gas diffusion layers KW - In-plane diffusion KW - Metal sheets KW - Microporous layers KW - Modeling process KW - Predictive capabilities KW - Water transport KW - Proton exchange membrane fuel cells (PEMFC) KW - Protons KW - Sheet metal KW - Diffusion in gases AB - The use of perforated metal sheets as engineered gas diffusion layers (GDL) in proton exchange membrane (PEM) fuel cells was investigated. The effect of different thicknesses, perforation diameter, and in-plane diffusion capabilities were analyzed along with freestanding microporous layers in order to improve gas and water transport. Although these structured GDLs are in an early stage of development, they provide baseline performance at lower current densities, and may already have potential for some specific applications. In addition, the design, manufacturing, and modeling processes with predictive capability can be improved due to their simplified nature. © 2011 The Electrochemical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 773e3be8-f9e1-4f4f-a582-42a624e044ea ER - TY - JOUR TI - Induced currents in the quantum Hall regime: Energy storage, persistence, and I-V characteristics DO - 10.1103/PhysRevB.86.195314 AU - Smith, M.J. AU - Usher, A. AU - Williams, C.D.H. AU - Shytov, A. AU - Sachrajda, A.S. AU - Kam, A. AU - Wasilewski, Z.R. T2 - Physical Review B - Condensed Matter and Materials Physics SN - 1098-0121 VL - 86 IS - 19 SP - 195314 AB - Induced currents associated with the quantum Hall effect are studied in the temperature range 39mK to 1.6K, and at Landau-level filling factors ν=1,2,3,4, and 6, using torsion-balance magnetometry. A quantitative link is demonstrated between (nonlinear induced current) vs (inducing electromotive force) curves, and the subexponential decay of the induced current in a static magnetic field. The energy storage in the induced currents is reexamined with the conclusion that the predominant mechanism for storage is inductive, through the mutual inductance between the sample and the magnet, not capacitive as previous reports have assumed. The temperature dependencies of the currents are consistent with previous models, except for a low-temperature saturation at filling factors ν=1 and ν=2, which we attribute to electron heating. © 2012 American Physical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4c0b5977-78cf-4b64-9ef0-9580f7669b4d ER - TY - JOUR TI - Mechanical property-porosity relationships of layered calcium silicate hydrate phases DO - 10.1617/s11527-012-9990-3 AU - Pourbeik, P. AU - Beaudoin, J.J. AU - Alizadeh, R. AU - Raki, L. T2 - Materials and Structures/Materiaux et Constructions SN - 1359-5997 SP - 1 EP - 7 AB - Dynamic mechanical analysis measurements were made on the following calcium-silicate- hydrate systems: 1.4 nm tobermorite (T), jennite (J), synthetic C-S-H (C/S = 0.80, 1.20 and 1.50) and cement paste. The age of the cement paste varied from 3 days to 45 years. Plots of storage modulus versus porosity were constructed for all these materials. The non-uniqueness of the curves is discussed with reference to Taylor's analysis of strength-porosity curves and the influence of particle type, density and crystallinity. Additional insights regarding the practical application of T-J and T-CH nanostructural models for the C-S-H nanostructure in hydrated cements is provided. © 2012 RILEM. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : de6a975e-e399-4bab-b503-bffe1202215c ER - TY - JOUR TI - Evaluation of sealed joint performance for the selection of sealants suitable for use in autoclaved lightweight concrete panels DO - 10.1520/STP154520120018 AU - Miyauchi, H. AU - Lacasse, M. A. AU - Murata, S. AU - Enomoto, N. AU - Tanak, K. T2 - ASTM Special Technical Publication T3 - 4th Durability of Building and Construction Sealants and Adhesives, 16 June 2011 through 17 June 2011, Anaheim, CA SN - 0066-0558 SN - 9780803175310 VL - 1545 STP SP - 385 EP - 403 KW - Earthquake load KW - Expansion and contraction KW - External walls KW - Joint fracture KW - Joint movement KW - Joint performance KW - Lightweight concrete panel KW - Long term performance KW - Low modulus KW - Modulus KW - Normal concretes KW - Sealant products KW - Shear joints KW - Shear tests KW - Static and dynamic KW - Test specimens KW - Two-component KW - Wall panels KW - Adhesion KW - Adhesives KW - Concrete slabs KW - Construction KW - Durability KW - Fatigue of materials KW - Fatigue testing KW - Fracture KW - Precast concrete KW - Substrates KW - Walls (structural partitions) KW - Sealants AB - The strength of autoclaved lightweight concrete (ALC) is evidently lower than that of normal concrete. Therefore, when movement occurs at a sealed joint between ALC panels, the sealant is required to deform and remain intact without damaging the ALC substrate. However, there is currently not sufficient information to permit evaluation of the expected performance of sealants applied to ALC substrates. In this study, static and dynamic tests were carried out in order to obtain an index that could be used to select the modulus of a sealant that can be expected to provide long-term performance when applied to an ALC substrate. To develop this index, an initial study was carried out in order to clarify actual joint movement between ALC panels of buildings; the expansion and contraction at the joint were measured, and shear joint movement was calculated based on the expected story-to-story drift of an external wall due to earthquake loads. Thereafter, in a subsequent stage of the study, five types of two-component polyurethane sealant products, of different elastic modulus, were subjected to tensile and shear tests from which the relationship between stress and the type of joint fracture was determined. The results from these tests revealed that when the stress is greater than 0.6 to 0.7 N/mm2, the ALC substrate is more easily fractured than the sealant. In a final stage of the study, the cyclic fatigue resistance of the same two-component sealants was evaluated using tensile and shear fatigue tests. Results from the fatigue tests indicated that the high modulus sealants lost adhesion from the ALC substrate at an early stage in the test. As well, the fatigue resistance of test specimens with joints having three-sided adhesion was lower than that of specimens having normally configured joints with adhesion on two sides of the sealant. Therefore, on the basis of results derived from all the studies, it was determined that a suitable sealant for use on ALC substrates is a sealant having a low modulus that is applied in the normal fashion as a two-sided joint. Copyright © 2012 by ASTM International. DA - 2012/07/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9d662482-b330-449c-9b27-73e59bb087f5 ER - TY - JOUR TI - Feasibility of infrared spectroscopy with pattern recognition techniques to identify a subpopulation of mares at risk of producing foals diagnosed with failure of transfer of passive immunity DO - 10.1111/j.1751-0813.2012.00979.x AU - Riley, C. AU - Mcclure, J. AU - Low-Ying, S. AU - Dolenko, B. AU - Somorjai, R. AU - Shaw, R. T2 - Australian Veterinary Journal SN - 0005-0423 VL - 90 IS - 10 SP - 387 EP - 391 KW - immunoglobulin G KW - animal KW - animal disease KW - article KW - blood KW - feasibility study KW - female KW - horse KW - horse disease KW - immunology KW - infrared spectroscopy KW - methodology KW - newborn KW - passive immunization KW - physiology KW - puerperium KW - sensitivity and specificity KW - Animals KW - Animals, Newborn KW - Feasibility Studies KW - Female KW - Horse Diseases KW - Horses KW - Immunity, Maternally-Acquired KW - Immunization, Passive KW - Immunoglobulin G KW - Postpartum Period KW - Sensitivity and Specificity KW - Spectroscopy, Fourier Transform Infrared AB - Objective: To assess the feasibility of a serum-based test using infrared spectroscopy to identify a subpopulation of mares at risk of producing foals susceptible to failure of passive transfer of immunity (FPT) because of mare-associated factors. Materials and methods: Serum was collected from post-parturient mares (n = 126) and their foals at 24-72h of age. A radial immunodiffusion IgG test was used to determine each foal's serum IgG concentration. Infrared absorbance spectra of dam sera were collected in the wave number range of 400-4000cm-1. Following data preprocessing, pattern recognition techniques were used to identify spectroscopic information capable of distinguishing between mares with FPT foals and those with normal foals. The sensitivity and specificity of infrared spectroscopy to detect risk-positive mares were calculated. Results: Five wave number regions were identified as optimal for distinguishing between the two groups of mares: 740.9-785.2cm-1, 796.8-816.0cm-1, 970.4-993.5cm-1, 1371.6-1406.3cm-1 and 1632.0-1659.0cm-1. Based upon the infrared spectroscopic information within these discriminatory subregions, the spectra provided the risk status of the mares with a classification success rate of 81.0%. The sensitivity of the classification system was 85.7% and specificity was 80.0%. Conclusion: This preliminary study demonstrates that infrared spectra of dam serum have the potential to provide the basis for a new periparturient screening method for a subpopulation of mares at risk of having a foal susceptible to FPT. Further development may provide an economic and rapid technique for the pre-parturient assessment of mares. © 2012 The Authors. Australian Veterinary Journal © 2012 Australian Veterinary Association. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 646d0933-3430-4ede-be26-49b00d2b0efa ER - TY - JOUR TI - CliFin: A web-based geographical information system for time dependant point of care localization in New Brunswick, Canada DO - 10.4018/jhisi.2012100103 AU - Tulpan, D. AU - Mancuso, M. AU - Durand, G. AU - Regoui, C. AU - Belliveau, L. T2 - International Journal of Healthcare Information Systems and Informatics SN - 1555-3396 VL - 7 IS - 4 SP - 32 EP - 47 KW - Canada KW - Clinic Finder (CliFin) KW - New Brunswick KW - Point of care KW - Web servers KW - Database systems KW - Health KW - Health care KW - Health insurance KW - Hospitals KW - Public health KW - Visualization KW - Websites KW - Geographic information systems AB - Over the past decade, the development of web-based Geographic Information Systems (GIS) for health has grown quite rapidly due to an increased need of data integration and spatial visualization. One GIS growth area in health is the construction of map-based applications that provide information on health care resources. Such applications are typically used as standard tools by public health departments, public health policy and research organizations, hospitals and health insurance organizations to provide public access to health care resources. This paper presents the design and development process of Clinic Finder (CliFin) - an open-access web-based GIS application relying on the Google Maps technology and providing access to a database with point of care facilities across the Province of New Brunswick, Canada. The uniqueness of CliFin consists in the implementation of a time-frame dependent search and results trimming approach, which allows users to identify clinics and hospitals open at any given time. The users are also encouraged to contribute with schedule updates and new point of care information to further develop CliFin's database and its accuracy. The combination of GIS visualization capabilities, database management, user involvement in database update and the time-frame dependence of search results, confers CliFin increased practicality, especially in situations of crisis such as natural disasters. Copyright © 2012, IGI Global. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0fb9a370-c409-4286-8147-8b506fb90cbc ER - TY - JOUR TI - Rolled-up 1.55 μm semiconductor quantum dot tube lasers DO - 10.1149/1.3700417 AU - Mi, Z. AU - Bianucci, P. AU - Tavakoli-Dastjerdi, M.H. AU - Mukherjee, S. AU - Djavid, M. AU - Poole, P.J. T2 - ECS Transactions T3 - 2nd International Symposium on Nanoscale Luminescent Materials - 221st ECS Meeting, 6 May 2012 through 10 May 2012, Seattle, WA SN - 1938-5862 SN - 9781566779579 VL - 45 IS - 5 SP - 113 EP - 118 KW - Continuous Wave KW - InGaAsP KW - Liquid nitrogen temperature KW - Optically pumped KW - Ultra-low threshold KW - Nanotechnology KW - Pumping (laser) KW - Semiconductor lasers KW - Semiconductor quantum dots KW - Tubes (components) KW - Optically pumped lasers AB - We report on the fabrication and characterization of InGaAsP/InAs quantum dot rolled-up tubes as well as the achievement of a semiconductor tube laser at ∼ 1.55 μn. The optically pumped tube laser operates in continuous wave at liquid nitrogen temperature and shows an ultra-low threshold of ∼1.26 μW. ©The Electrochemical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7737dbb0-44aa-4821-8756-31f69e881ffb ER - TY - JOUR TI - Mid-IR broadband quantum cascade laser frequency-comb AU - Hugi, A. AU - Blaser, S. AU - Liu, H.C. AU - Faist, J. T2 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012 T3 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012, 6 May 2012 through 11 May 2012, San Jose, CA SN - 9781467318396 SP - 6325913 KW - Phase signature KW - Quantum cascade lasers KW - Lasers AB - We show a free-running broadband QCL emitting a frequency-comb of 490 nm at 7μm whose spectral phase signature resembles to the one of a frequency-modulate laser. Beatnote-linewidths as narrow as f < 10Hz are measured. © 2012 OSA. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c1d2ebe8-3d7b-4c18-aa0d-59628cbb2752 ER - TY - JOUR TI - The JCMT Nearby Galaxies Legacy Survey - VIII. CO data and the L CO(3-2)-L FIR correlation in the SINGS sample DO - 10.1111/j.1365-2966.2012.21453.x AU - Wilson, C.D. AU - Warren, B.E. AU - Israel, F.P. AU - Serjeant, S. AU - Attewell, D. AU - Bendo, G.J. AU - Butner, H.M. AU - Chanial, P. AU - Clements, D.L. AU - Golding, J. AU - Heesen, V. AU - Irwin, J. AU - Leech, J. AU - Matthews, H.E. AU - Mühle, S. AU - Mortier, A.M.J. AU - Petitpas, G. AU - Sánchez-Gallego, J.R. AU - Sinukoff, E. AU - Shorten, K. AU - Tan, B.K. AU - Tilanus, R.P.J. AU - Usero, A. AU - Vaccari, M. AU - Wiegert, T. AU - Zhu, M. AU - Alexander, D.M. AU - Alexander, P. AU - Azimlu, M. AU - Barmby, P. AU - Brar, R. AU - Bridge, C. AU - Brinks, E. AU - Brooks, S. AU - Coppin, K. AU - Côté, S. AU - Côté, P. AU - Courteau, S. AU - Davies, J. AU - Eales, S. AU - Fich, M. AU - Hudson, M. AU - Hughes, D.H. AU - Ivison, R.J. AU - Knapen, J.H. AU - Page, M. AU - Parkin, T.J. AU - Rigopoulou, D. AU - Rosolowsky, E. AU - Seaquist, E.R. AU - Spekkens, K. AU - Tanvir, N. AU - van der Hulst, J.M. AU - van der Werf, P. AU - Vlahakis, C. AU - Webb, T.M. AU - Weferling, B. AU - White, G.J. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 424 IS - 4 SP - 3050 EP - 3080 AB - The James Clerk Maxwell Telescope Nearby Galaxies Legacy Survey (NGLS) comprises an Hi-selected sample of 155 galaxies spanning all morphological types with distances less than 25Mpc. We describe the scientific goals of the survey, the sample selection and the observing strategy. We also present an atlas and analysis of the CO J=3 - 2 maps for the 47 galaxies in the NGLS which are also part of the Spitzer Infrared Nearby Galaxies Survey. We find a wide range of molecular gas mass fractions in the galaxies in this sample and explore the correlation of the far-infrared luminosity, which traces star formation, with the CO luminosity, which traces the molecular gas mass. By comparing the NGLS data with merging galaxies at low and high redshift, which have also been observed in the CO J=3 - 2 line, we show that the correlation of far-infrared and CO luminosity shows a significant trend with luminosity. This trend is consistent with a molecular gas depletion time which is more than an order of magnitude faster in the merger galaxies than in nearby normal galaxies. We also find a strong correlation of the L FIR/L CO(3-2) ratio with the atomic-to-molecular gas mass ratio. This correlation suggests that some of the far-infrared emission originates from dust associated with atomic gas and that its contribution is particularly important in galaxies where most of the gas is in the atomic phase. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 712aaed6-e584-4971-9ce1-efe71833d8c7 ER - TY - JOUR TI - Microbial characteristics and influence factors during anaerobic fermentation for biohydrogen production from CO DO - 10.3724/SP.J.1145.2012.00656 AU - Zhao, Y. AU - Liu, Z. AU - Liu, F. AU - Guiot, S.R. T2 - Chinese Journal of Applied and Environmental Biology SN - 1006-687X VL - 18 IS - 4 SP - 656 EP - 660 KW - Bacteria (microorganisms) KW - Carboxydothermus hydrogenoformans AB - The biohydrogen production from anaerobic fermentation was studied with thermophilic bacterium Carboxydothermus hydrogenoformans using carbon monoxide (CO) dissolved in fermentation broth as the substrate. Bacterium growth model, decay efficient and the maximum specific growth rate were observed based on the experimental study of biomass growing, flocculation and microbial characteristics. The results indicated the feasibility of continuous anaerobic fermentation for hydrogen production from CO with C. hydrogenoformans due to its good hydrogen yield and flocculation ability. Furthermore, by investigating the effect of procedure parameters during CO fermentation, the optimal feed/microorganism was proposed and the maximum CO concentration was observed to avoid CO inhibition which was the key factor to consider in the study of continuous biohydrogen production from CO fermentation. DA - 2012 PY - 2012 LA - zho C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c8c4b2eb-d501-4acf-805d-79d0105fab24 ER - TY - JOUR TI - Review of tools for friction stir welding and processing DO - 10.1179/1879139512Y.0000000015 AU - Zhang, Y.N. AU - Cao, X. AU - Larose, S. AU - Wanjara, P. T2 - Canadian Metallurgical Quarterly SN - 0008-4433 VL - 51 IS - 3 SP - 250 EP - 261 KW - Bottom surfaces KW - Casting defect KW - Downward pressure KW - Environmental friendliness KW - Friction stir processing KW - Green manufacturing technique KW - Manufacturing applications KW - Mechanical and physical properties KW - Solid-state joining KW - Stir zones KW - Thin layers KW - Tool designs KW - Work pieces KW - Corrosion resistance KW - Energy efficiency KW - Friction stir welding KW - Gas welding KW - Joining KW - Mechanical properties KW - Probes KW - Shoulders (road) KW - Tools KW - Processing AB - Friction stir welding (FSW) is a novel green manufacturing technique due to its energy efficiency and environmental friendliness. This solid state joining process involves a rotating tool consisting of a shoulder and/or a probe. The shoulder applies a downward pressure to the workpiece surface, constrains the plasticised material around the probe, generates heat through the friction and causes plastic deformation in a relatively thin layer under the bottom surface of the shoulder. The rotating probe mainly drags along, plasticises, and mixes the adjacent material in the stir zone, creating a joint without fusion. Friction stir processing (FSP), a variant of FSW, has been developed to manufacture composites, locally eliminate casting defects, refine microstructure and/or improve the associated mechanical and physical properties including strength, ductility, fatigue, creep, formability and corrosion resistance. However, major challenges such as tool design and wear currently limit the use of FSW/P for manufacturing applications, particularly for high melting temperature or high strength alloys. In this review, the FSW/P tools are briefly summarised in terms of the tool types, shapes, dimensions, materials and wear behaviours. © 2012 Crown in Right of Canada. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9ff325c8-2a7a-4765-8a04-8f53053d1139 ER - TY - JOUR TI - CAM-based planning, programming and execution of large-scale machining operations by a robot-mounted gantry system AU - Lambert, J.M. AU - de Montigny, M. AU - Perron, C. T2 - SAE International Journal of Materials and Manufacturing SN - 1946-3979 VL - 5 IS - 1 SP - 30 EP - 40 KW - Automatically generated KW - Cad/cams KW - Calibration procedure KW - Complex geometries KW - Conventional machines KW - Gantry system KW - Iterative process KW - Kinematic model KW - Machining operations KW - On-line process monitoring KW - Path generation KW - Positioning precision KW - Process performance KW - Production modes KW - Program generation KW - Program management KW - Robot machining KW - Robot programs KW - Robot trajectory KW - Robotic systems KW - Surface data KW - Toolpaths KW - Trajectory information KW - Cams KW - Machining centers KW - Process monitoring KW - Robotics KW - Robots KW - User interfaces KW - Robot programming AB - This paper examines issues related to planning, programming and execution of machining operations by a robot in the context of machining large parts with complex geometries by a gantry-mounted robotic system. Parts were created from surface data in a CAD/CAM environment. The same environment was used to generate tool paths using a conventional machine tool approach. These paths were converted to robot trajectories and validated using mathematical kinematic models of the robotic system. Validation was performed according to various criteria related to process performance. Associated robot programs were then automatically generated. The manufacturing cell was progressively integrated according to requirements resulting from iterative process characterization. A metrology-based calibration procedure was designed that considerably improved the system's positioning precision. A custom user interface for online process monitoring was created as well as online cell program management capabilities to accommodate the large quantity of trajectory information. The system went from conceptual, to prototype-level to full production mode, thereby covering several Manufacturing Readiness Levels (MRL). The various strategies used in planning the process and programming the system demonstrate the viability of CAM-based approach for robot machining path generation without resorting to the use of OLP packages for validation of program generation. This could create a shift in the dependency on robotic specialists, allowing machine tool experts to carry about the programming of robot machining cells using the conventional machine tool approach. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : da75e831-0c7a-4b3d-a95b-21c1c2a2ff86 ER - TY - JOUR TI - Structures of merkel cell polyomavirus VP1 complexes define a sialic acid binding site required for infection DO - 10.1371/journal.ppat.1002738 AU - Neu, U. AU - Hengel, H. AU - Blaum, B.S. AU - Schowalter, R.M. AU - Macejak, D. AU - Gilbert, M. AU - Wakarchuk, W.W. AU - Imamura, A. AU - Ando, H. AU - Kiso, M. AU - Arnberg, N. AU - Garcea, R.L. AU - Peters, T. AU - Buck, C.B. AU - Stehle, T. T2 - PLoS Pathogens SN - 1553-7366 VL - 8 IS - 7 SP - e1002738 SP - 8 KW - glycosaminoglycan KW - protein VP1 KW - sialic acid KW - capsid protein KW - glycosaminoglycan KW - n acetylneuraminic acid KW - oligosaccharide KW - virus DNA KW - virus receptor KW - VP1 protein, polyomavirus KW - article KW - binding site KW - cell adhesion KW - complex formation KW - crystallization KW - epitope mapping KW - ligand binding KW - merkel cell polyomavirus KW - mutagenesis KW - nonhuman KW - nucleotide sequence KW - protein expression KW - protein purification KW - protein structure KW - virus attachment KW - virus entry KW - virus morphology KW - virus mutation KW - cell line KW - chemical structure KW - chemistry KW - genetics KW - human KW - metabolism KW - mutation KW - physiology KW - polyomavirus infection KW - protein conformation KW - virology KW - X ray crystallography KW - Miridae KW - Polyomavirus KW - Binding Sites KW - Capsid Proteins KW - Cell Line KW - Crystallography, X-Ray KW - DNA, Viral KW - Epitope Mapping KW - Glycosaminoglycans KW - Humans KW - Merkel cell polyomavirus KW - Models, Molecular KW - Mutation KW - N-Acetylneuraminic Acid KW - Oligosaccharides KW - Polyomavirus Infections KW - Protein Conformation KW - Receptors, Virus KW - Virus Attachment KW - Virus Internalization AB - The recently discovered human Merkel cell polyomavirus (MCPyV or MCV) causes the aggressive Merkel cell carcinoma (MCC) in the skin of immunocompromised individuals. Conflicting reports suggest that cellular glycans containing sialic acid (Neu5Ac) may play a role in MCPyV infectious entry. To address this question, we solved X-ray structures of the MCPyV major capsid protein VP1 both alone and in complex with several sialylated oligosaccharides. A shallow binding site on the apical surface of the VP1 capsomer recognizes the disaccharide Neu5Ac-α2,3-Gal through a complex network of interactions. MCPyV engages Neu5Ac in an orientation and with contacts that differ markedly from those observed in other polyomavirus complexes with sialylated receptors. Mutations in the Neu5Ac binding site abolish MCPyV infection, highlighting the relevance of the Neu5Ac interaction for MCPyV entry. Our study thus provides a powerful platform for the development of MCPyV-specific vaccines and antivirals. Interestingly, engagement of sialic acid does not interfere with initial attachment of MCPyV to cells, consistent with a previous proposal that attachment is mediated by a class of non-sialylated carbohydrates called glycosaminoglycans. Our results therefore suggest a model in which sialylated glycans serve as secondary, post-attachment co-receptors during MCPyV infectious entry. Since cell-surface glycans typically serve as primary attachment receptors for many viruses, we identify here a new role for glycans in mediating, and perhaps even modulating, post-attachment entry processes. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4eca4a79-d037-4cef-bb0c-3021af035519 ER - TY - JOUR TI - Effect of dietary protein level and source on digestive proteolytic enzyme activity in juvenile Senegalese sole, Solea senegalensis Kaup 1850 DO - 10.1007/s10499-012-9508-6 AU - Rodiles, A. AU - Santigosa, E. AU - Herrera, M. AU - Hachero-Cruzado, I. AU - Cordero, M.L. AU - Martínez-Llorens, S. AU - Lall, S.P. AU - Alarcón, F.J. T2 - Aquaculture International SN - 0967-6120 VL - 20 IS - 6 SP - 1053 EP - 1070 KW - diet KW - enzyme activity KW - flatfish KW - food supplementation KW - growth response KW - hydrolysis KW - inhibitor KW - juvenile KW - physiology KW - protein KW - soybean KW - Animalia KW - Glycine max KW - Pisum sativum KW - Solea senegalensis KW - Soleidae KW - Triticum aestivum AB - The effect of dietary protein level and protein source on growth and proteolytic activity of juvenile Solea senegalensis was studied. In Experiment 1, fish were fed on four experimental diets containing increased protein levels (36, 46, 56 and 67%). In Experiment 2, Senegalese soles were fed on five diets with partial substitution of fish meal by soybean meal, soybean protein concentrate, soybean protein isolate, wheat gluten meal or pea protein concentrate. Results prove that growth and proteolytic activity in the distal intestine of fish were affected by the quantitative increase in dietary protein. The origin of protein source used in the elaboration of experimental diets affected both the amount and composition of the alkaline proteases secreted into the intestinal lumen; however, it did not decrease animal growth. Juvenile Senegalese sole showed capability to modulate digestive protease secretion when the concentration and/or source of dietary protein were modified. Quantity and quality of dietary protein affected protein hydrolysis in Senegalese sole intestine. This study establishes that 30% fish meal protein can be replaced by soybean derivatives without affecting intestinal proteases. Replacement with wheat gluten meal or pea protein concentrate should be taken cautiously, but further research is needed to establish whether growth performance and digestive enzyme physiology of Senegalese sole are affected by plant protein-supplemented diets in a long-term trial. © 2012 Springer Science+Business Media B.V. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 440eb3ce-3fdb-4363-9b73-1e297a181b0a ER - TY - JOUR TI - Induction of tolerogenic dendritic cells by IL-6-secreting CT26 colon carcinoma DO - 10.3109/08923973.2011.625034 AU - Alshamsan, A. T2 - Immunopharmacology and Immunotoxicology SN - 0892-3973 VL - 34 IS - 3 SP - 465 EP - 469 KW - CD40 antigen KW - CD86 antigen KW - interleukin 6 KW - lipopolysaccharide KW - STAT3 protein KW - animal cell KW - animal tissue KW - article KW - bone marrow KW - cancer cell culture KW - cancer immunotherapy KW - cell lineage KW - cell maturation KW - colon carcinoma KW - dendritic cell KW - down regulation KW - flow cytometry KW - mouse KW - nonhuman KW - priority journal KW - protein phosphorylation KW - Animals KW - Antigens, CD40 KW - Antigens, CD86 KW - Cell Line, Tumor KW - Colonic Neoplasms KW - Dendritic Cells KW - Immune Tolerance KW - Immunotherapy KW - Interleukin-6 KW - Mice KW - Mice, Inbred BALB C KW - Neoplasm Proteins KW - NIH 3T3 Cells KW - Phosphorylation KW - STAT3 Transcription Factor KW - Murinae AB - One scenario by which tumors escape immune recognition is the constitutive activation of signal transducer and activator of transcription 3 (STAT3). This transcription factor mediates the production of tumor-derived factors that negatively influence target immune cells, such as dendritic cells, and polarize them toward immune-tolerance also through the induction of STAT3 activation. In the current study, the effect of p-STAT3-positive murine colon carcinoma cell line (CT26) on bone marrow-derived DCs was examined. The results showed a remarkable increase in p-STAT3 in dendritic cells (DCs) only after CT26-CM incubation. The induction of p-STAT3 in CT26-CM exposed DCs was attributed at least in part to the high levels of interleukin-6 secreted by CT26 in culture. This was also accompanied by a significant reduction in the response to the immunostimulatory adjuvant lipopolysaccharide by lowering the expression of co-stimulatory molecules CD86 and CD40. Taken together, the results suggest an inhibitory effect of CT26 colon carcinoma on DC maturation through induction of STAT3 phosphorylation. Therefore, tumor-induced p-STAT3 in DCs can be seen as a promising target for colon cancer immunotherapy. © 2012 Informa Healthcare USA, Inc. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e2ec11df-1df0-4a6f-9c85-09ae2eecd95f ER - TY - JOUR TI - Characterization of the lipopolysaccharide from Pasteurella multocida Heddleston serovar 9: Identification of a proposed bi-functional dTDP-3-acetamido-3,6-dideoxy-α-D-glucose biosynthesis enzyme DO - 10.1093/glycob/cwr147 AU - Harper, M. AU - St. Michael, F. AU - Vinogradov, E. AU - John, M. AU - Boyce, J.D. AU - Adler, B. AU - Cox, A.D. T2 - Glycobiology SN - 0959-6658 VL - 22 IS - 3 SP - 332 EP - 344 KW - 3 acetamido 3,6 dideoxy alpha dextro glucose KW - bacterium lipopolysaccharide KW - glucose derivative KW - glycosyltransferase KW - heptose KW - monosaccharide KW - rhamnose KW - thymidine diphosphate KW - unclassified drug KW - amino terminal sequence KW - article KW - bacterial gene KW - bacterial genetics KW - bacterial strain KW - carbohydrate analysis KW - carboxy terminal sequence KW - controlled study KW - genetic analysis KW - gluconeogenesis KW - mass spectrometry KW - methylation KW - nonhuman KW - nuclear magnetic resonance spectroscopy KW - nucleotide sequence KW - Pasteurella multocida KW - Pasteurella multocida serovar 9 KW - priority journal KW - qdtD gene KW - Amino Acid Sequence KW - Bacterial Proteins KW - Carbohydrate Conformation KW - Carbohydrate Sequence KW - Deoxy Sugars KW - Genes, Bacterial KW - Genetic Loci KW - Glycosyltransferases KW - Lipopolysaccharides KW - Mass Spectrometry KW - Molecular Sequence Data KW - Pasteurella multocida KW - Sequence Homology, Amino Acid KW - Thymine Nucleotides KW - Pasteurella multocida AB - Pasteurella multocida strains are classified into 16 different lipopolysaccharide (LPS) serovars using the Heddleston serotyping scheme. Ongoing studies in our laboratories on the LPS aim to determine the core oligosaccharide (OS) structures expressed by each of the Heddleston type strains and identify the genes and transferases required for the biosynthesis of the serovar-specific OSs. In this study, we have determined the core OS of the LPS expressed by the Heddleston serovar 9 type strain, P2095. Structural information was established by a combination of monosaccharide and methylation analyses, nuclear magnetic resonance spectroscopy and mass spectrometry revealing the following structure: The serovar 9 OS contains an inner core that is conserved among P. multocida strains with an elaborate outer core extension containing rhamnose (Rha), a D-glycero-D-manno isomer of heptose, and the unusual deoxyamino sugar, 3-acetamido-3,6-dideoxy-d-glucose (Qui3NAc). Genetic analyses of the LPS outer core biosynthesis locus revealed that in addition to the glycosyltransferases predicted to transfer the sugars to the nascent LPS molecule, the locus also contained the complete set of genes required for the biosynthesis of the nucleotide sugar donors dTDP-Rha and dTDP-Qui3NAc. One of the genes identified as part of the dTDP-Qui3NAc biosynthesis pathway, qdtD, encodes a proposed bi-functional enzyme with N-terminal amino acid identity to dTDP-4-oxo-6-deoxy-d-glucose-3,4-oxoisomerase and C-terminal amino acid identity to dTDP-3-oxo-6-deoxy-D-glucose transacetylase. © The Author 2011. Published by Oxford University Press. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9b517c3f-3303-4af6-97b0-838ea04438fa ER - TY - JOUR TI - Dual-source swept-source optical coherence tomography reconstructed on integrated spectrum DO - 10.1155/2012/565823 AU - Chang, S. AU - Mao, Y. AU - Flueraru, C. T2 - International Journal of Optics SN - 1687-9384 VL - 2012 SP - 565823 AB - Dual-source swept-source optical coherence tomography (DS-SSOCT) has two individual sources with different central wavelengths, linewidth, and bandwidths. Because of the difference between the two sources, the individually reconstructed tomograms from each source have different aspect ratio, which makes the comparison and integration difficult. We report a method to merge two sets of DS-SSOCT raw data in a common spectrum, on which both data have the same spectrum density and a correct separation. The reconstructed tomographic image can seamlessly integrate the two bands of OCT data together. The final image has higher axial resolution and richer spectroscopic information than any of the individually reconstructed tomography image. Copyright © 2012 Shoude Chang et al. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f1453d71-e08d-489d-a949-af0c3cda4870 ER - TY - JOUR TI - Real-time control of angioplasty balloon inflation based on feedback from intravascular optical coherence tomography: Experimental validation on an excised heart and a beating heart model DO - 10.1109/TBME.2012.2189884 AU - Azarnoush, H. AU - Vergnole, S. AU - Boulet, B. AU - Sowa, M. AU - Lamouche, G. T2 - IEEE Transactions on Biomedical Engineering SN - 0018-9294 VL - 59 IS - 5 SP - 6166864 SP - 1488 EP - 1495 KW - Angioplasty KW - Balloon inflation KW - Beating heart KW - Coronary arteries KW - Experimental validations KW - Feed-back loop KW - In-vivo KW - Inflation process KW - Intravascular KW - Programmable syringe pump KW - Real time KW - Target values KW - Balloons KW - Control KW - Experiments KW - Optical tomography KW - Real time control KW - Heart KW - animal experiment KW - artery constriction KW - article KW - balloon catheter KW - control system KW - controlled study KW - feedback system KW - flow rate KW - heart beat KW - heart surgery KW - nonhuman KW - optical coherence tomography KW - percutaneous transluminal angioplasty KW - syringe KW - Algorithms KW - Angioplasty, Balloon KW - Animals KW - Feedback KW - Heart KW - Models, Cardiovascular KW - Pressure KW - Swine KW - Tomography, Optical Coherence AB - We report on real-time control of balloon inflation inside porcine arteries. In the first step, experiments were done in a coronary artery of an excised heart. In the second step, experiments were done in a beating heart setup providing conditions very close to in vivo conditions without the complications. A programmable syringe pump was used to inflate a compliant balloon in arteries, while intravascular optical coherence tomography (IVOCT) monitoring was performed. In a feedback loop, IVOCT images were processed to provide the balloon diameter values in real time to control the pump action in order to achieve a target diameter. In different experiments, various flow rates and target diameters were used. In the excised heart experiment, there was good convergence to target diameters resulting in a satisfactory balloon inflation control. In the beating heart experiment, there were oscillations in the diameter values due to cyclic arterial contractions. In these experiments, the control system maintained diameter averages satisfactorily close to predetermined target values. Real-time control of balloon inflation could not only provide a safer outcome for angioplasty procedures, but could also provide additional information for diagnostics since it implicitly provides information about the artery response to the inflation process. © 1964-2012 IEEE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b4719974-50af-4298-80ae-eb170904fd63 ER - TY - JOUR TI - Soot emission measurement in flares by Sky-LOSA: Reduction of uncertainty in field measurements AU - Devillers, R.W. AU - Thomson, K.A. AU - Johnson, M.R. T2 - Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA T3 - 105th Air and Waste Management Association Annual Conference and Exhibition 2012, ACE 2012, 19 June 2012 through 22 June 2012, San Antonio, TX SN - 1052-6102 SN - 9781622764778 VL - 3 SP - 2141 EP - 2146 AB - Sky-LOSA, an extension of Line-of-Sight Attenuation (LOSA) that is commonly used in laboratory-scale experiments for soot concentration measurements, was applied to a small flare in Poza Rica, Mexico. An average soot emission rate of 057 g/sec was obtained from 1.5 min of data. The uncertainty associated to velocity measurement was studied. Using a single ensemble averaged velocity in place of instantaneous velocity measurements synchronized with transmissivity measurements led to a 13% underestimation of the average soot emission rate. Uncertainty associated with integration along the optical axis was 7%. Sky-LOSA remains promising for investigation of particulate matter emissions in flares. This is an abstract of a paper presented at the 105th AWMA Annual Conference and Exhibition (San Antonio, TX 6/19-22/2012). DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 69eb9e12-4dac-49d4-bb66-a0f291d89974 ER - TY - JOUR TI - From laterally modulated two-dimensional electron gas towards artificial graphene DO - 10.1088/1367-2630/14/5/053002 AU - Nádvorník, L. AU - Orlita, M. AU - Goncharuk, N.A. AU - Smrčka, L. AU - Novák, V. AU - Jurka, V. AU - Hruška, K. AU - Výborný, Z. AU - Wasilewski, Z.R. AU - Potemski, M. AU - Výborný, K. T2 - New Journal of Physics SN - 1367-2630 VL - 14 SP - 53002 KW - Effective potentials KW - Far-infrared KW - GaAs KW - Lateral patterning KW - Lateral superlattice KW - Miniband structures KW - Minibands KW - Nonlinear dependence KW - Perturbative calculations KW - Resonance position KW - Electron gas KW - Magnetic fields KW - Graphene AB - Cyclotron resonance has been measured in far-infrared transmission of GaAs/Al xGa 1-xAs heterostructures with an etched trigonal lateral superlattice intended to mimic graphene with lattice constant of the order of 100 nm (about 1000 times larger than that of natural graphene). Nonlinear dependence of the resonance position on magnetic field was observed, as well as its splitting into several modes. Our explanation, based on a perturbative calculation, describes the observed phenomena as a weak effect of the lateral potential on the twodimensional electron gas. Using this approach, we found a correlation between parameters of the lateral patterning and the created effective potential and obtained thus insights into how the electronic miniband structure has been tuned. The miniband dispersion was calculated using a simplified model and allowed us to formulate four basic criteria that have to be satisfied to reach graphene-like physics in such systems. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 98df1053-ffa2-4e9f-a621-48bbca4a80b9 ER - TY - JOUR TI - Optical simulation and fabrication of periodic triangular gratings for the enhancement of photovoltaic solar panels DO - 10.1117/12.916786 AU - Dey, R. AU - Bordatchev, E.V. AU - Tauhiduzzaman, M. AU - Reshef, H. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Physics, Simulation, and Photonic Engineering of Photovoltaic Devices, 23 January 2012 through 26 January 2012, San Francisco, CA SN - 0277-786X SN - 9780819488992 VL - 8256 SP - 82561Z KW - Cost effective KW - Energy industry KW - Incident light KW - Incident light power KW - Incident power KW - Light-trapping KW - Micro-optical structure KW - Optical parameter KW - Optical performance KW - Optical simulation KW - Optical structures KW - Optical surfaces KW - Orientation angles KW - Photovoltaic KW - Photovoltaic panels KW - Photovoltaic performance KW - PV panel KW - PV performance KW - Solar panels KW - Top surface KW - Total internal reflections KW - Triangular gratings KW - Computer simulation KW - Microfabrication KW - Optimization KW - Photonic devices KW - Photovoltaic cells KW - Refractive index KW - Solar concentrators KW - Photovoltaic effects AB - The solar energy industry strives to produce more and more efficient and yet cost effective photovoltaic (PV) panels. Integration of specific micro/nano optical structures on the top surface of the PV panels is one of the efficient ways to increase their PV performance through enhancing light trapping and in-coupling. In this study, periodic triangular gratings (PTGs) in polymethyl methacrylate (PMMA) were numerically simulated and optimized. The goal of this study is to enhance the ability of solar panels to convert maximum obtainable amount of solar energy by improving the optical in-coupling of light to PV material. Initial optical simulation results shown that a flat PV panel (without any enhancing micro-optical structures) exhibits an average incident light power of 0.327 W over a range of the incident light angles between 15° and 90°. Introduction of the PTG allows capturing the incoming sunlight and reflecting it back onto the PV material for a second or more chances for absorption and conversion into electricity. The light trapping and redirection is achieved through the total internal reflection (TIR) phenomenon. Geometry of the PTG was initially optimized with respect to an incident sunlight orientation of 15°, 30°, 45°, 60°, 75°, and 90°. Optical performance of the particular optimized PTGs was analyzed over daylight conditions and several optical parameters, such as average incident power and intensity, were calculated when sunlight orientation angle was changing from 15° to 90°. By adding the PTG optimized for 15° incidents light, an average incident power of 0.342 W was achieved (4.6% improvement of optical performance). Functional PTG prototypes were fabricated with optical surface quality (below 10 nm R a). The simulation results allow understanding how the overall daytime photovoltaic performance of solar panels can be improved. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f9846fbd-62c3-45a9-b346-6e893cc4388b ER - TY - JOUR TI - The central blue straggler population in four outer-halo globular clusters DO - 10.1088/0004-637X/754/2/108 AU - Beccari, G. AU - Lützgendorf, N. AU - Olczak, C. AU - Ferraro, F.R. AU - Lanzoni, B. AU - Carraro, G. AU - Stetson, P.B. AU - Sollima, A. AU - Boffin, H.M.J. T2 - The Astrophysical Journal SN - 0004-637X VL - 754 IS - 2 SP - 108 AB - Using Hubble Space Telescope/Wide Field Planetary Camera 2 data, we have performed a comparative study of the Blue Straggler Star (BSS) populations in the central regions of the globular clusters (GCs) AM 1, Eridanus, Palomar 3, and Palomar 4. Located at distances R GC > 50kpc from the Galactic center, these are (together with Palomar 14 and NGC2419) the most distant clusters in the halo. We determine their color-magnitude diagrams and centers of gravity. The four clusters turn out to have similar ages (10.5-11Gyr), significantly smaller than those of the inner-halo globulars, and similar metallicities. By exploiting wide-field ground-based data, we build the most extended radial density profiles from resolved star counts ever published for these systems. These are well reproduced by isotropic King models of relatively low concentration. BSSs appear to be significantly more centrally segregated than red giants in all GCs, in agreement with the estimated core and half-mass relaxation times which are smaller than the cluster ages. Assuming that this is a signature of mass segregation, we conclude that AM 1 and Eridanus are slightly dynamically more evolved than Pal 3 and Pal 4. © 2012. The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7ab5aeb4-c922-4c0c-8868-662358f2c606 ER - TY - JOUR TI - Evolution of space charges and conductivity with dc aging of polyethylene-synthetic and natural clay composites DO - 10.1155/2012/463748 AU - Abou-Dakka, M. T2 - Journal of Nanomaterials SN - 1687-4110 VL - 2012 SP - 463748 KW - Aging time KW - DC field KW - Double layers KW - Interaction zone KW - Material interfaces KW - Nano-fillers KW - Nanofiller KW - Natural clays KW - Optimal concentration KW - Organoclays KW - Percolation thresholds KW - Synthetic clays KW - Total charge KW - Interfaces (materials) KW - Polypropylenes KW - Thermoplastics AB - The evolution of the space charge and conductivity with DC poling of two types of polypropylene-(PP-) based nanocomposites (PNCs) was investigated. The PNCs were manufactured with different concentrations of synthetic and natural organoclays. The optimal concentrations of nanofiller that can efficiently mitigate the space charge with DC aging time were 2-wt% for PP-natural-clay and between 2 and 4 wt% for the PP-synthetic-clay. Above these percentages charge transport through overlapping of nanoparticles can occur due to the interaction zone of double layers formed at the nanoparticle/host material interfaces. Under DC field the overlapping increases the conductivity of PNCs and minimizes the benefit of incorporating nanofillers into PP. The total charge stored in unfilled PP increased continuously with time reaching a maximum around 5000 h before decreasing but it also changed slightly in all filled specimens. It was perceived that the smaller the size of nanofiller platelets the more efficient the charge mitigation. The conductivity of specimens containing 6 wt% of natural clay and 8 wt% of synthetic clay reached ≈6 times the level of the unfilled PP. This observation could be related and due to the crossing of the percolation threshold for these composites. © 2012 Mahmoud Abou-Dakka. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 572d0b4b-eda0-4342-9192-d820714ba091 ER - TY - JOUR TI - Thermo-mechanical properties of 5-harness satin fabric composites DO - 10.1177/0021998312436990 AU - Khoun, L. AU - Challagulla, K. AU - Hubert, P. T2 - Journal of Composite Materials SN - 0021-9983 VL - 46 IS - 25 SP - 3121 EP - 3136 KW - Cross-ply KW - cure KW - Cure kinetics KW - Cure progress KW - Effective property KW - Elastic properties KW - Fabric composites KW - Material property KW - Micromechanical approach KW - Residual strains KW - Resin processing KW - Thermomechanical properties KW - Three-dimensional units KW - Unit cells KW - Woven fabric composites KW - Woven textiles KW - Biomechanics KW - Composite materials KW - Composite micromechanics KW - Curing KW - Elasticity KW - Finite element method KW - Micromechanics KW - Structural design KW - Weaving AB - The use of woven textile reinforcements in composite structures increased significantly in the past decades due to their interesting properties over unidirectional fibres. Therefore, the prediction of the thermo-mechanical properties of woven fabric composites is essential from a design and manufacturing standpoint. A micromechanical approach based on finite element method that utilizes three-dimensional unit cell was applied to predict the effective properties of a periodic woven fabric composite material. Using the resin processing properties models such as cure kinetics, shrinkage, glass transition temperature and elastic modulus models, the development of the periodic woven fabric composite material thermo-mechanical properties, as the cure progresses was predicted. The residual strains and stresses generated in the composite unit cell during the cure were also predicted and linked with the development of the material properties. The effective properties of the cured woven fabric composite material were compared to the one of an equivalent cross-ply composite material to verify the validity of neglecting the fibre waviness while modelling woven fabric composite. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : dba10233-58bb-49f1-8dfe-a22d64d7628f ER - TY - JOUR TI - A VL single-domain antibody library shows a high-propensity to yield non-aggregating binders DO - 10.1093/protein/gzs014 AU - Hussack, G. AU - Keklikian, A. AU - Alsughayyir, J. AU - Hanifi-Moghaddam, P. AU - Arbabi-Ghahroudi, M. AU - Van Faassen, H. AU - Hou, S.T. AU - Sad, S. AU - MacKenzie, R. AU - Tanha, J. T2 - Protein Engineering, Design and Selection SN - 1741-0126 VL - 25 IS - 6 SP - 313 EP - 318 KW - Antibody library KW - Complementarity-determining regions KW - non-aggregating KW - Phage display libraries KW - Single domains KW - Antibodies KW - Antigens KW - Scaffolds KW - Binders KW - antibody KW - bacterial antigen KW - bacterial protein KW - bacterial toxin KW - immunoglobulin light chain KW - single chain fragment variable antibody KW - toxB protein, Clostridium difficile KW - antibody library KW - antigen expression KW - article KW - codon KW - controlled study KW - dissociation KW - enzyme linked immunosorbent assay KW - human KW - polyacrylamide gel electrophoresis KW - priority journal KW - scanning electron microscopy KW - solubility KW - amino acid sequence KW - antibody affinity KW - chemistry KW - genetics KW - metabolism KW - molecular cloning KW - molecular genetics KW - nucleotide sequence KW - peptide library KW - protein binding KW - Amino Acid Sequence KW - Antibody Affinity KW - Antigens, Bacterial KW - Bacterial Proteins KW - Bacterial Toxins KW - Base Sequence KW - Cloning, Molecular KW - Enzyme-Linked Immunosorbent Assay KW - Humans KW - Immunoglobulin Light Chains KW - Molecular Sequence Data KW - Peptide Library KW - Protein Binding KW - Single-Chain Antibodies AB - A synthetic human VL phage display library, created by the randomization of all complementarity-determining regions (CDRs) in a V L scaffold, was panned against three test antigens to determine the propensity of the library to yield non-aggregating binders. A total of 22 binders were isolated against the test antigens and the majority (20) were monomeric. Thus, human VL repertoires provide an efficient source of non-aggregating binders and represent an attractive alternative to human V H repertoires, which are notorious for containing high proportions of aggregating species. Moreover, the solubility of VLs, in contrast to VHs, appears much less CDR dependent. © The Author 2012. Published by Oxford University Press. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3cce1590-8dbb-4117-8281-e32f3e6de1f7 ER - TY - JOUR TI - Mitigation of transient meteor events in sodium layer by TMT NFIRAOS DO - 10.1117/12.924926 AU - Herriot, G. AU - Irvin, C. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Adaptive Optics Systems III, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491480 VL - 8447 SP - 844734 KW - Burn up KW - Centroiding KW - Control architecture KW - Defocus KW - Focus measurement KW - Focus sensors KW - Frame rate KW - Meteor trails KW - Meteors KW - NFIRAOS KW - Normal condition KW - Shack-Hartmann KW - Simulink simulations KW - Sky coverage KW - Sodium layer KW - Spot displacement KW - TMT KW - Tracking errors KW - Wavefront errors KW - Blending KW - Computer simulation KW - Errors KW - Ionization of gases KW - Magnetohydrodynamics KW - Optical radar KW - Optimization KW - Sodium KW - Electric appliances AB - NFIRAOS Small meteors usually burn up near the bottom of the sodium layer. Meteor trails can lead to temporary dramatic changes in the altitude of the sodium layer. This altitude change is very rapid, typically over 1 second, and after some unpredictable period of 10-20 seconds, can transition back to the nominal mean altitude also in about 1 second. The altitude change is very drastic and can jump by up to 1 km which, on the face of it, would cause 4 micrometers defocus errors on LGS WFS measurements for a 30-m telescope, unless properly tracked. Measurements by the UBC Lidar detected ~20 meteor trails / hour, and of these, 1-2 are significant events. We report on a full end-to-end Simulink simulation for TMT NFIRAOS including: meteor events measured by the UBC Lidar; on-instrument NGS focus sensor running at 90 Hz (median sky coverage frame rate); optimal temporal blending with LGS WFS focus measurements; LGS WFS centroiding matched filter update and Truth WFS update very 3s; full trombone servo model including non-linear focus range vs stage position. We optimized our control architecture and traded off motor power dissipation versus residual wavefront error and Shack-Hartmann spot displacement and found range tracking errors induce 12 nm WFE in normal conditions and brief (1s) jumps of 30-80 nm WFE at the beginning and ending of meteor transients. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 70e2b992-62d9-4908-a440-bfb42a23910a ER - TY - JOUR TI - ALMA band 3 cartridge maintenance plan DO - 10.1117/12.925549 AU - Yeung, K. AU - Seifried, K. AU - Randolph, W. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Modeling, Systems Engineering, and Project Management for Astronomy V, 1 July 2012 through 3 July 2012, Amsterdam SN - 0277-786X SN - 9780819491503 VL - 8449 SP - 84491C KW - 100 GHz KW - Construction phase KW - Front end KW - Maintenance and operation KW - Maintenance plans KW - Memorandum of understanding KW - Repair services KW - Test systems KW - University of Calgary KW - Warranty period KW - Work packages KW - Astrophysics KW - Project management KW - Radio astronomy KW - Repair KW - Systems engineering KW - Projectiles AB - Under the "Memorandum of Understanding between the National Radio Astronomy Observatory (NRAO)/Associated Universities Incorporated (AUI), Herzberg Institute of Astrophysics (HIA) and the University of Calgary related to Canadian ALMA Construction Phase Work Packages", HIA is committed to deliver a suite of seventy-three Band 3 100 GHz receiver cartridges to the ALMA Project. After the acceptance of each cartridge at the Front End Integration Centers, HIA is responsible to perform any post-delivery maintenance, repair or rework of the cartridges for a warranty period of up to one year. This paper defines a framework for the maintenance and repair services for the Band 3 cartridges after the post-delivery warranty period has expired. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d1ccdf17-0cf3-4527-b39a-1b6e2e0c781c ER - TY - JOUR TI - Evidence for a non-universal stellar initial mass function in low-redshift high-density early-type galaxies DO - 10.1111/j.1745-3933.2012.01230.x AU - Dutton, A.A. AU - Mendel, J.T. AU - Simard, L. T2 - Monthly Notices of the Royal Astronomical Society: Letters SN - 1745-3933 VL - 422 IS - 1 SP - L33 EP - L37 AB - We determine an absolute calibration of stellar mass-to-light ratios for the densest ≃3 per cent of early-type galaxies in the local Universe (redshift z ≃ 0.08) from Sloan Digital Sky Survey (SDSS) Data Release 7. This sample of ~4000 galaxies has, assuming a Chabrier initial mass function (IMF), effective stellar surface densities Σe > 2500M ⊙ pc -2, stellar population synthesis (SPS) stellar masses log10(M SPS/M ⊙) < 10.8 and aperture velocity dispersions of σap = 168 +37 -34 km s -1 (68 per cent range). In contrast to typical early-type galaxies, we show that these dense early-type galaxies follow the virial Fundamental Plane, which suggests that mass follows light. With the additional assumption that any dark matter does not follow the light, the dynamical masses of dense galaxies provide a direct measurement of stellar masses. Our dynamical masses (M dyn), obtained from the spherical Jeans equations, are only weakly sensitive to the choice of anisotropy (β) due to the relatively large aperture of the SDSS fibre for these galaxies: R ap - 1.5R e. Assuming isotropic orbits (β = 0), we find a median log10(M dyn/M SPS) = 0.233 ± 0.003, consistent with a Salpeter IMF, while more bottom-heavy IMFs and standard MilkyWay IMFs are strongly disfavoured. Our results are consistent with, but do not require, a dependence of the IMF on dynamical mass or velocity dispersion. We find evidence for a colour dependence to the IMF such that redder galaxies have heavier IMFs with Mdyn/MSPS α (g - r) 1.13 ±0.09. This may reflect a more fundamental dependence of the IMF on the age or metallicity of a stellar population, or the density at which the stars formed. © 2012 The Authors. Monthly Notices of the Royal Astronomical Society © 2012 RAS. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8d4b03a4-c977-4235-ba1b-c7e92e384da3 ER - TY - JOUR TI - Characteristics of gadolinia-doped ceria films deposited by spray pyrolysis AU - Halmenschlager, C.M. AU - Neagu, R. AU - De Fraga Malfatti, C. AU - Bergmann, C.P. T2 - Materials Science and Technology Conference and Exhibition 2012, MS and T 2012 T3 - Materials Science and Technology Conference and Exhibition 2012, MS and T 2012, 7 October 2012 through 11 October 2012, Pittsburgh, PA SN - 9781622766536 VL - 1 SP - 409 EP - 416 KW - Acetylacetonates KW - Cerium ammonium nitrates KW - Gadolinia doped ceria KW - Gadolinium doped ceria KW - Intermediate temperature solid oxide fuel cell KW - Porous substrates KW - Postdeposition heat treatment KW - Van der Pauw technique KW - Deposits KW - Electrolytes KW - Exhibitions KW - Gadolinium KW - Ionic conductivity KW - Materials science KW - Optimization KW - Sintering KW - Solid oxide fuel cells (SOFC) KW - Spray pyrolysis KW - Thermal spraying KW - Thin films KW - Vapor deposition AB - Nowadays the challenges on SOFC are to find a way to produce good quality electrolyte, which does not need sintering at high temperature. This work presents the results of a process optimization applied to gadolinia-doped ceria thin films deposited by spray pyrolysis (SP). The aim of this work was to achieve thin, dense, and continuous CGO coatings, which may serve as electrolyte for SOFC. Dense substrates were used as substrates for the deposition. Cerium ammonium nitrate and gadolinium acetylacetonate were used as precursors' salts. Parameters such as gas flow, liquid flow and temperature were studied. Controlling these parameters, thin, dense, crack-free films could be produced on dense and porous substrates. X-ray diffraction (XRD) analysis showed that the films were crystalline after the deposition without requiring post-deposition heat treatment. Van der Pauw technique showed that the produced films have good conductivity, suitable for use as intermediate temperature solid oxide fuel cell electrolytes. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 576449ff-3f11-40bf-9c0f-c2a0a559522d ER - TY - JOUR TI - Fast light-emitting silicon-germanium nanostructures DO - 10.1149/1.3700407 AU - Lockwood, D.J. AU - Wu, X. AU - Baribeau, J.-M. AU - Modi, N. AU - Tsybeskov, L. T2 - ECS Transactions T3 - 2nd International Symposium on Nanoscale Luminescent Materials - 221st ECS Meeting, 6 May 2012 through 10 May 2012, Seattle, WA SN - 1938-5862 SN - 9781566779579 VL - 45 IS - 5 SP - 31 EP - 42 KW - Carrier recombination KW - CMOS Compatible KW - Light emitters KW - Light emitting devices KW - Si/SiGe KW - Silicon Germanium KW - Spectral range KW - Germanium KW - Silicon alloys KW - Nanostructures AB - Epitaxially-grown three-dimensional Si/SiGe nanostructures produce photoluminescence and electroluminescence in the desired spectral range of 1.3-1.6 μm. We show that by controlling and modifying such Ge-rich SiGe nanoclusters during growth it is possible to fabricate very fast and hence more efficient SiGe light-emitting devices. Models for the physics of carrier recombination in these Si/SiGe nanostructures are presented, and a new route toward CMOS compatible light emitters is proposed. ©The Electrochemical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2fdddbcb-5e5c-46fc-ad77-42b716aa33ab ER - TY - JOUR TI - Acoustic upgrades to wind tunnels at the National Research Council Canada AU - Syms, G.F. T2 - 18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference) T3 - 18th AIAA/CEAS Aeroacoustics Conference 2012 (33rd AIAA Aeroacoustics Conference), 4 June 2012 through 6 June 2012 SN - 9781600869327 KW - Acoustic environment KW - Acoustic treatment KW - Aerospace configurations KW - Aircraft manufacturers KW - Array measurements KW - National Research Council KW - Reduction strategy KW - Stainless steel mesh KW - Aeroacoustics KW - Aircraft KW - Airframes KW - Landing gear (aircraft) KW - Microphones KW - Noise abatement KW - Research KW - Structural frames KW - Wind tunnels KW - Acoustic noise AB - Airframe noise is growing a concern for aircraft manufacturers, operators and commu- nities. The ability to determine the location and strength of noise sources on an aircraft or its components allows noise reduction strategies to be developed which can have sig- nificant impact on the overall noise signature of the aircraft. Phased-microphone array measurement technologies have become an effective tool in noise source localization for aerospace configurations. With the growing national need to address airframe noise is- sues, the National Research Council Canada upgraded two of its wind tunnels to provide a better acoustic environment to make phased-array measurements. The first facility to be upgraded in 2009 was the 0.9m 3/4-open jet low speed research tunnel in which the original metal turning vanes on the corners bounding the test section were replaced with vanes lined with acoustic foam. This reduced the background noise in the test section by 5 - 10dB depending upon the frequency with little reduction in maximum tunnel speed. The second facility to receive an acoustic treatment was the 2m x 3m closed circuit tunnel in 2011. For this facility, an acoustic liner was developed for the test section which allowed the microphones to be recessed out of the flow and decreased the reverberant nature of the hard-walled tunnel. All walls of the tunnel were covered with acoustic foam-filled boxes covered with a stainless steel mesh. This reduced the background noise measured by the recessed microphone array by 15 - 20dB compared to a flush mounted array. In each up-graded facility, an aeroacoustic test of a two-wheel main landing gear of a business jet was carried out (the first at 1/3rd-scale and the second at full scale). Results in the large tunnel show accurate noise source localization with repeatability of 0.15dB for the loudest source and 0.25dB for the second loudest noise source. The two successful wind tunnel entries show the effectiveness of the two wind tunnel acoustic upgrades. © 2012 by Government of Canada. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 439992e5-035b-40a9-b7e3-2140a07ca86c ER - TY - JOUR TI - Cyclic voltammetry of Zn/Zn(II) couple in dicyanamide anion and bis-(trifluoromethylsulfonyl)imide anion based ionic liquids DO - 10.1149/05025.0013ecst AU - Xu, M. AU - Ivey, D.G. AU - Qu, W. AU - Xie, Z. AU - Bing, Y.H. T2 - ECS Transactions T3 - Symposium on Metal-Air Batteries - 222nd ECS Meeting/PRiME 2012, 7 October 2012 through 12 October 2012, Honolulu, HI SN - 1938-5862 SN - 9781607684138 VL - 50 IS - 25 SP - 13 EP - 22 KW - Aqueous electrolyte KW - Bis(trifluoromethane sulfonyl)imide KW - Dicyanamide KW - Dicyanamide anion KW - Electron transfer process KW - Room temperature ionic liquids KW - Zn deposits KW - Zn particles KW - Cyclic voltammetry KW - Deposits KW - Morphology KW - Particles (particulate matter) KW - Scanning electron microscopy KW - Zinc KW - Zinc deposits KW - Ionic liquids AB - The electrochemistry of a Zn/Zn(II) couple was studied and compared in four kinds of room temperature ionic liquids (RTILs) (1-butyl-1-methylpyrrolidinium dicyanamide (BMP-DCA), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide (EMI-TFSI), 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (BMP-TFSI) and 1-methyl-1-pentylpyrrolidinium bis(trifluoromethanesulfonyl)imide (MPP-TFSI)), with the aim of screening desirable RTILs as replacements for traditional aqueous electrolytes for Zn rechargeable batteries. Cyclic voltammetry was used to study the reversibility and cyclability of Zn redox in each RTIL. The morphology of Zn deposits prepared from each RTIL was characterized by scanning electron microscopy. The results show that Zn redox has the best cyclability in the DCA-based RTIL, with the Zn deposit morphology characterized by finely dispersed rods composed of granular Zn particles (∼50-100 nm in size). In TFSI-based ionic liquids, the Zn/Zn(II) couple reaction had a higher current density than that in the DCA-based ionic liquid, implying different electron transfer processes. BMP-DCA and EMI-TFSI are promising RTILs worthy of further investigation. © The Electrochemical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 183f6dc4-ee1b-4385-82b1-30f831c314ad ER - TY - JOUR TI - A high-resolution study of the H I-H 2 transition across the perseus molecular cloud DO - 10.1088/0004-637X/748/2/75 AU - Lee, M.-Y. AU - Stanimirović, S. AU - Douglas, K.A. AU - Knee, L.B.G. AU - Di Francesco, J. AU - Gibson, S.J. AU - Begum, A. AU - Grcevich, J. AU - Heiles, C. AU - Korpela, E.J. AU - Leroy, A.K. AU - Peek, J.E.G. AU - Pingel, N.M. AU - Putman, M.E. AU - Saul, D. T2 - The Astrophysical Journal SN - 0004-637X VL - 748 IS - 2 SP - 75 AB - To investigate the fundamental principles of H 2 formation in a giant molecular cloud, we derive the H I and H 2 surface density (Σ H I and Σ H2) images of the Perseus molecular cloud on sub-pc scales (0.4pc). We use the far-infrared data from the Improved Reprocessing of the IRAS Survey and the V-band extinction image provided by the COMPLETE Survey to estimate the dust column density image of Perseus. In combination with the H I data from the Galactic Arecibo L-band Feed Array H I Survey and an estimate of the local dust-to-gas ratio, we then derive the Σ H2 distribution across Perseus. We find a relatively uniform Σ H I6-8 Mpc -2 for both dark and star-forming regions, suggesting a minimum H I surface density required to shield H 2 against photodissociation. As a result, a remarkably tight and consistent relation is found between Σ H2/Σ H I and Σ H I + Σ H2. The transition between the H I- and H 2-dominated regions occurs at N(H I) + 2N(H 2) (8-14)× 10 20cm -2. Our findings are consistent with predictions for H 2 formation in equilibrium, suggesting that turbulence may not be of primary importance for H 2 formation. However, the importance of a warm neutral medium for H 2 shielding, an internal radiation field, and the timescale of H 2 formation still remain as open questions. We also compare H 2 and CO distributions and estimate the fraction of "CO-dark" gas, f DG 0.3. While significant spatial variations of f DG are found, we do not find a clear correlation with the mean V-band extinction. © 2012. The American Astronomical Society. All rights reserved.. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 24219958-a3cb-4e6f-bddd-c2e89e21467a ER - TY - CHAP TI - Proton Conductivity of Aromatic Polymers DO - 10.1002/9781119962502.ch9 AU - Liu, B. AU - Guiver, M.D. T2 - Solid State Proton Conductors: Properties and Applications in Fuel Cells SN - 9780470669372 SP - 331 EP - 369 DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 38ac31de-d8db-43b4-b78e-494fb3ee150b ER - TY - JOUR TI - Microstructure and high temperature tensile properties of wide gap brazed cobalt based superalloy X-40 AU - Henhoeffer, T. AU - Huang, X. AU - Yand, S. AU - Au, P. AU - Nagy, D. T2 - Energy Materials: Materials Science and Engineering for Energy Systems SN - 1748-9237 VL - 5 IS - 2 SP - 431 EP - 439 KW - Cobalt-based superalloy KW - High temperature tensile properties KW - IN738 KW - Microstructure characterisation KW - Nanoindentation techniques KW - Ultimate tensile strength KW - Wide-gap brazing KW - X-40 KW - Boron KW - Cerium alloys KW - Cobalt KW - Gas turbines KW - High temperature properties KW - Microstructure KW - Superalloys KW - Tensile strength KW - Tensile testing KW - Brazing AB - Wide gap brazing (WGB) of X-40 cobalt based superalloy was conducted in this study using BNi-9 braze alloy with X-40 and IN738 additive alloys. A groove was machined into X-40 bars with a nominal width of 6?35 mm before filler application. Following brazing at 1200°C for 15 min, the microstructure of the as brazed joints was examined using SEM, EDS and nanoindentation technique. Both WGB joints with X-40 and IN783 additive alloys contained primary matrix phase in addition to a number of boron containing phases which assumed either eutectic or discrete forms. Nanoindention testing revealed that these boron containing phases exhibited hardness values several times higher than the base alloy and matrix phase contributing to the embrittlement of the braze joint. Porosity was also observed in both types of WGB braze joints, the degree of which was greatest in the braze joints with IN738 additive alloy. Tensile testing at 950uC showed that the yield strength of both WGB joints was higher than that of the baseline specimens while the ultimate tensile strength of the WGB joints was lower than that of the baseline X-40. The ductility of the WGB joints was significantly inferior to that of the baseline X-40, particularly for WGB with IN 738 additive alloy. © 2010 Institute of Materials, Minerals and Mining. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 79e6df72-ba8d-4b90-8e28-687914181979 ER - TY - JOUR TI - Compression moulding of discontinuous-fibre carbon/PEEK composites: Study of mechanical properties AU - Selezneva, M. AU - Picher-Martel, G.-P. AU - Landry, B. AU - Trudel-Boucher, D. AU - Roy, S. AU - Khoun, L. AU - Hojjati, M. AU - Lessard, L. AU - Hubert, P. T2 - International SAMPE Technical Conference T3 - 2012 SAMPE International Symposium and Exhibition - Emerging Opportunities: Materials and Process Solutions, 21 May 2012 through 24 May 2012, Baltimore, MD SN - 9781934551127 KW - ASTM Standards KW - Carbon/PEEK KW - Flat panel KW - Material behaviour KW - Measured properties KW - Mesostructures KW - Moulding process KW - Multi-disciplinary KW - Properties of composites KW - Quasi-static KW - Sensitivity studies KW - Tensile loading KW - Compression molding KW - Exhibitions KW - Mechanical testing KW - Mechanical properties AB - A new multi-disciplinary study is being conducted to systematically evaluate, characterize and model the moulding process and mechanical properties of composites manufactured fro mrandomly-oriented carbon/PEEK chopped strips. The heterogeneous meso-structure of this material is expected to give rise to unique material behaviour, which is not entirely accounted for in the current ASTM standards for mechanical testing. This paper presents results of a sensitivity study aimed to evaluate the dependence of measured properties on the size of the coupon gauge section. Coupons of different widths (12.5 - 50 mm) were cut from compression moulded flat panels of randomly oriented chopped strips 25 mm in length and were subjected to quasi-static tensile loading. Results did not show any noticeable effect of the coupon width on the measured properties. Tensile strength and stiffness were found to be substantially lower than those of quasi-isotropic continuous fiber laminates, 59 % and 26 % lower, respectively. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 61d8e95d-edef-4a92-b51d-f036637500a6 ER - TY - JOUR TI - Term MRI for small preterm babies: Do parents really want to know and why has nobody asked them? DO - 10.1111/j.1651-2227.2012.02767.x AU - Pearce, R. AU - Baardsnes, J. T2 - Acta Paediatrica, International Journal of Paediatrics SN - 0803-5253 VL - 101 IS - 10 SP - 1013 EP - 1015 KW - carbon dioxide KW - nitrous oxide KW - bacterial infection KW - blood transfusion KW - brain hemorrhage KW - case report KW - cerebellum injury KW - child KW - family stress KW - female KW - gestational age KW - human KW - infant KW - intestine perforation KW - mycosis KW - newborn intensive care KW - newborn mortality KW - nuclear magnetic resonance imaging KW - parental attitude KW - patient education KW - personal experience KW - positive end expiratory pressure KW - prematurity KW - preschool child KW - priority journal KW - review KW - septic shock KW - ventilator KW - Brain Injuries KW - Cerebellar Cortex KW - Cerebral Hemorrhage KW - Female KW - Health Knowledge, Attitudes, Practice KW - Humans KW - Infant, Newborn KW - Infant, Premature KW - Infant, Premature, Diseases KW - Infection KW - Intensive Care Units, Neonatal KW - Magnetic Resonance Imaging KW - Parents KW - Prognosis KW - Shock, Septic KW - Twins DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6157d652-985d-4bfe-90b5-46599ed92389 ER - TY - JOUR TI - Probabilistic risk analysis for aircraft structures with limited in-service damages AU - Liao, M. AU - Bombardier, Y. AU - Renaud, G. T2 - 28th Congress of the International Council of the Aeronautical Sciences 2012, ICAS 2012 T3 - 28th Congress of the International Council of the Aeronautical Sciences 2012, ICAS 2012, 23 September 2012 through 28 September 2012, Brisbane SN - 9781622767540 VL - 3 SP - 2016 EP - 2026 KW - Aircraft structure KW - CP-140 KW - Damage tolerance analysis KW - Maintenance Action KW - Operational life KW - Probabilistic risk analysis KW - Probability of failure KW - Structural risks KW - Aerodynamics KW - Aircraft KW - Aircraft manufacture KW - Airframes KW - Fits and tolerances KW - Risk analysis KW - Risk assessment KW - Location based services AB - This paper presents some recent results of NRC research on risk assessment for aircraft structures. First, this paper briefly reviews the Canadian Forces (CF) risk assessment requirements related to aircraft structural life assessment. Because the single flight probability of failure (SFPOF) (instantaneous failure rate) is an important parameter used in aircraft risk assessment, a critical review of different SFPOF definitions and calculations is presented. As the size of the CF aircraft fleet is relatively small, one common issue encountered during risk assessment is that only a limited number of inservice damage findings are available. Several methods are discussed for preparing input data, especially the initial crack size distribution (ICSD), from small samples for structural risk analysis. To demonstrate one of the in-service damage based methods, a risk analysis case study is presented, in which limited in-service damage findings were used to calculate the SFPOF at a wing location, in support of the CF risk-based decision-making on maintenance actions and the operational life limit. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 58f0707d-9dcc-4760-b404-54381f23d444 ER - TY - JOUR TI - The resonant trans-Neptunian populations DO - 10.1088/0004-6256/144/1/23 AU - Gladman, B. AU - Lawler, S.M. AU - Petit, J.-M. AU - Kavelaars, J. AU - Jones, R.L. AU - Parker, J.W. AU - Van Laerhoven, C. AU - Nicholson, P. AU - Rousselot, P. AU - Bieryla, A. AU - Ashby, M.L.N. T2 - Astronomical Journal SN - 0004-6256 VL - 144 IS - 1 SP - 23 AB - The trans-Neptunian objects (TNOs) trapped in mean-motion resonances with Neptune were likely emplaced there during planet migration late in the giant-planet formation process. We perform detailed modeling of the resonant objects detected in the Canada-France Ecliptic Plane Survey (CFEPS) in order to provide population estimates and, for some resonances, constrain the complex internal orbital element distribution. Detection biases play a critical role because phase relationships with Neptune make object discovery more likely at certain longitudes. This paper discusses the 3:2, 5:2, 2:1, 3:1, 5:1, 4:3, 5:3, 7:3, 5:4, and 7:4 mean-motion resonances, all of which had CFEPS detections, along with our upper limit on 1:1 Neptune Trojans (which is consistent with their small population estimated elsewhere). For the plutinos (TNOs in the 3:2 resonance) we refine the orbital element distribution given by Kavelaars et al. in 2009 and show that steep H-magnitude distributions (N(H)10 αH, with α = 0.8-0.9) are favored in the range H g = 8-9, and confirm that this resonance does not share the inclination distribution of the classical Kuiper Belt. We give the first population estimate for the 5:2 resonance and find that, to within the uncertainties, the population is equal to that of the 3:2 (≃13,000 TNOs with H g < 9.16), whereas the 2:1 population is smaller by a factor of 3-4 compared to the other two resonances. We also measure significant populations inhabiting the 4:3, 5:3, 7:3, 5:4, 7:4, 3:1, and 5:1 resonances, with H g < 9.16 (D > 100km) populations in the thousands. We compare our intrinsic population and orbital element distributions with several published models of resonant-TNO production; the most striking discrepancy is that resonances beyond the 2:1 are in reality more heavily populated than in published models. © 2012. The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : df43d76f-c00e-40e3-905b-f007e7a96b27 ER - TY - JOUR TI - Electronic properties of gated triangular graphene quantum dots: Magnetism, correlations, and geometrical effects DO - 10.1103/PhysRevB.85.075431 AU - Potasz, P. AU - Güçlü, A.D. AU - Wójs, A. AU - Hawrylak, P. T2 - Physical Review B - Condensed Matter and Materials Physics SN - 1098-0121 VL - 85 IS - 7 SP - 75431 AB - We present a theory of electronic properties of gated triangular graphene quantum dots with zigzag edges as a function of size and carrier density. We focus on electronic correlations, spin, and geometrical effects using a combination of atomistic tight-binding, Hartree-Fock, and configuration interaction methods (TB+HF+CI), including long-range Coulomb interactions. The single-particle energy spectrum of triangular dots with zigzag edges exhibits a degenerate shell at the Fermi level with a degeneracy N edge proportional to the edge size. We determine the effect of the electron-electron interactions on the ground state, the total spin, and the excitation spectrum as a function of a shell filling and the degeneracy of the shell using TB+HF+CI for N edge<12 and approximate CI method for N edge≥12. For a half-filled neutral shell we find spin-polarized ground state for structures up to N=500 atoms in agreement with previous ab initio and mean-field calculations and in agreement with Lieb's theorem for a Hubbard model on a bipartite lattice. Adding a single electron leads to the complete spin depolarization for N edge≤9. For larger structures, the spin depolarization is shown to occur at different filling factors. Away from half-fillings excess electrons(holes) are shown to form Wigner-like spin-polarized triangular molecules corresponding to large gaps in the excitation spectrum. The validity of conclusions is assessed by a comparison of results obtained from different levels of approximations. While for the charge-neutral system all methods give qualitatively similar results, away from the charge neutrality an inclusion of all Coulomb scattering terms is necessary to produce results presented here. © 2012 American Physical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3e095486-eed6-48ee-af7c-7a4fe824f9fb ER - TY - JOUR TI - Stearoyl-CoA desaturase activity modulates the activation of epidermal growth factor receptor in human lung cancer cells DO - 10.1258/ebm.2012.012126 AU - Nashed, M. AU - Chisholm, J.W. AU - Ariel Igal, R. T2 - Experimental Biology and Medicine SN - 1535-3702 VL - 237 IS - 9 SP - 1007 EP - 1017 KW - acyl coenzyme A desaturase 1 KW - acyl coenzyme A desaturase inhibitor KW - cvt 11127 KW - enzyme inhibitor KW - epidermal growth factor receptor KW - gefitinib KW - mammalian target of rapamycin KW - mitogen activated protein kinase KW - monounsaturated fatty acid KW - protein kinase B KW - saturated fatty acid KW - unclassified drug KW - article KW - cancer cell KW - cell membrane KW - cell metabolism KW - cell proliferation KW - cell survival KW - controlled study KW - cytotoxicity KW - drug effect KW - drug potentiation KW - drug sensitivity KW - enzyme activity KW - enzyme inhibition KW - human KW - human cell KW - lipid blood level KW - lung cancer KW - microenvironment KW - mitogenesis KW - protein phosphorylation KW - Antineoplastic Agents KW - Cell Line, Tumor KW - Cell Proliferation KW - Cell Survival KW - Cell Transformation, Neoplastic KW - Extracellular Signal-Regulated MAP Kinases KW - Humans KW - Lung Neoplasms KW - MAP Kinase Signaling System KW - Phosphatidylinositol 3-Kinases KW - Phosphorylation KW - Proto-Oncogene Proteins c-akt KW - Quinazolines KW - Receptor, Epidermal Growth Factor KW - Stearoyl-CoA Desaturase KW - TOR Serine-Threonine Kinases KW - Mammalia AB - Stearoyl-CoA desaturase-1 (SCD1), the main enzyme that converts saturated fatty acids into monounsaturated fatty acids, is a key factor in the mechanisms of cancer cell proliferation, survival and tumorigenesis. Evidence indicates that SCD1 activity regulates these events in part by targeting the phosphatidylinositol-3 phosphate kinase/Akt and Ras/extracellular signalregulated kinase (ERK) pathways, but the molecular mechanisms remain unknown. We now show that in H460 lung cancer cells, the suppression of SCD activity with CVT-11127, a specific small molecule SCD inhibitor, impairs the ligand-induced phosphorylation of epidermal growth factor (EGF) receptor, causing the inactivation of its downstream targets Akt, ERK and mammalian target of rapamycin. Importantly, the mitogenic response to EGF was markedly defective in SCD-depleted cancer cells. The inactivation of EGF receptor (EGFR) promoted by SCD inhibition may be caused by perturbations in the lipid microenvironment surrounding the receptor, since we detected significant alterations in the lateral mobility of plasma lipid microdomains. Finally, incubation of lung cancer cells with SCD blockers potentiated the antigrowth effect of gefitinib, an EGFR inhibitor employed in cancer treatment. Altogether, our data indicate that SCD activity may control cancer cell metabolism, proliferation and survival by modulating the EGFR→Akt/ERK signaling platforms. Our studies also suggest a value for SCD inhibitors as novel pharmacological agents in lung cancer, one of the most common and lethal forms of cancer for which therapeutic options remain very limited. © 2008 Society for Experimental Biology and Medicine. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0f6064d7-67c2-43f0-91c6-ffdcab23ffe5 ER - TY - JOUR TI - Cryogenic mechanical design: SPIROU spectrograph DO - 10.1117/12.927442 AU - Reshetov, V. AU - Herriot, G. AU - Thibault, S. AU - Désaulniers, P. AU - Saddlemyer, L. AU - Loop, D. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Ground-Based and Airborne Instrumentation for Astronomy IV, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491473 VL - 8446 SP - 84464E KW - Mechanical design KW - Modelica KW - Multi-domain modeling KW - Optical Bench KW - Optical Mounts KW - Opto-mechanical design KW - Radial velocity KW - Spectropolarimeters KW - Thermal budget KW - Thermal control KW - Thermal designs KW - Thermomechanical stability KW - Astronomy KW - Design KW - Infrared spectrographs KW - Instruments KW - Spectrographs KW - Thermoanalysis KW - Thermodynamic stability KW - Cryogenics AB - This paper presents an overview of the PDR level mechanical and opto-mechanical design of the cryogenic spectrograph unit of the nIR spectropolarimeter (SPIROU) proposed as a new-generation instrument for CFHT. The design is driven by the need for high thermo-mechanical stability in terms of the radial velocity (RV) of 1 m/s during one night, with the requirement for thermal stability set at 1 mK/24 hours. This paper describes stress-free design of the cryogenic optical mounts, mechanical design of the custom-build cryostat, mechanical design of the optical bench, and thermal design for 1 mK thermal stability. The thermal budget was calculated using lumped-mass model thermal analysis, implemented in Modelica multi-domain modeling language. Discussion of thermal control options to achieve 1 mK thermal stability is included. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a8a6d3d1-4caa-44ed-934d-9ee0682f7004 ER - TY - JOUR TI - Feasibility studies to upgrade the Canada-France-Hawaii Telescope site for the Next Generation Canada-France-Hawaii Telescope DO - 10.1117/12.926682 AU - Szeto, K. AU - Angers, M. AU - Breckenridge, C. AU - Bauman, S. AU - Loewen, N. AU - Loop, D. AU - McConnachie, A. AU - Pazder, J. AU - Salmon, D. AU - Spano, P. AU - Stiemer, S. AU - Veillet, C. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Ground-Based and Airborne Telescopes IV, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491459 VL - 8444 SP - 84440W KW - ACI KW - Advisory committee KW - Air flow KW - AISC KW - ASCE KW - Baseline concepts KW - Dome seeing KW - Feasibility studies KW - Fixed base KW - Load capacity KW - Logical sequences KW - Multiobject KW - Structural interface KW - Technical decision KW - Technical study KW - Thermal study KW - Wide-field KW - Airborne telescopes KW - Computational fluid dynamics KW - Domes KW - Enclosures KW - Piers KW - Planning KW - Optical telescopes AB - The Next Generation Canada-France-Hawaii Telescope is a dedicated, 10m aperture, wide-field, fiber-fed multi-object spectroscopic facility proposed as an upgrade to the existing Canada-France-Hawaii Telescope on the summit of Mauna Kea. The Next Generation Canada-France-Hawaii Telescope baseline concept assumes the new facility is built on the existing Canada-France-Hawaii Telescope telescope pier and enclosure pier and occupies the same three dimensional exterior "footprint". Three technical studies have been planned to examine the validity of these assumptions. The technical studies are executed in series as they represent technical decision points in a logical sequence. The three technical studies in succession are: 1. Telescope Pier Study - Load Capacity and Structural Interface, 2. Enclosure Fixed Base Study - Telescope and Enclosure Configuration and Load Capacity and 3. Aero- Thermal Study - Dome Thermal Seeing and Air Flow Attenuation over the Enclosure Aperture Opening. The paper outlines the baseline facility (telescope, spectrograph and enclosure) concept and the status of these studies, and discusses the proposed telescope and enclosure configuration in terms of the redevelopment assumptions. A consolidated feasibility study report will be submitted to the CFHT Board and Science Advisory Committee in the Fall of 2012, with first light for the facility aiming to be in the early 2020s. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0b242703-071d-471f-a472-ddca39a1c120 ER - TY - JOUR TI - Wind uplift performance of composite metal roof assemblies DO - 10.1061/(ASCE)AE.1943-5568.0000042 AU - Baskaran, A. AU - Molleti, S. AU - Ko, S. AU - Shoemaker, L. T2 - Journal of Architectural Engineering SN - 1076-0431 VL - 18 IS - 1 SP - 2 EP - 15 KW - Air intrusion KW - Composite assembly KW - Dynamic tests KW - Dynamic wind loads KW - Metal roofing system KW - Non-composite KW - Panel deflection KW - Wind uplift resistance KW - Composite materials KW - Metals KW - Roofs KW - Testing KW - Wind effects KW - Surface resistance AB - A common factor in roof failures is wind forces, which inflict considerable damage every year, even to new roof structures. Metal roofs are a popular low-sloped roof assembly. On the basis of their layout, metal roofs can be categorized as either composite or noncomposite assemblies. In North American practice, five main test procedures - ASTM E1592, ANSI/FM 4474, UL 580, UL 1817, and CSA A123.21-04 - are used to determine the wind uplift performance of metal roofs. The fundamental differences between these test protocols lie in the way they represent wind effects on the performance of metal roofing systems. Of the five, CSA A 123.21-04 is the only one that assesses the wind uplift resistance under dynamic wind load conditions. To evaluate the wind uplift performance of noncomposite and composite metal roofing assemblies, eight assemblies with two different types of panels - SNAP-IT and MR-24 - were tested by using the CSA A123.21-04 dynamic test protocol. By relating air intrusion characteristics of the subsurface components to panel behavior, this paper shows how composite assemblies resist wind uplift pressures better than noncomposite assemblies. This paper reveals that increased air intrusion resistance of the sub surface components in composite assemblies results in increased suction resistance, decreased panel deflection, decreased stress on the panels, and increased wind uplift resistance. © 2012 American Society of Civil Engineers. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 54920af4-94f0-4c6d-bc67-5cf0985d647e ER - TY - JOUR TI - Radiation shielding materials and radiation scatter effects for interventional radiology (IR) physicians DO - 10.1118/1.4730504 AU - McCaffrey, J.P. AU - Tessier, F. AU - Shen, H. T2 - Medical Physics SN - 0094-2405 VL - 39 IS - 7 SP - 4537 EP - 4546 KW - article KW - equipment KW - equipment design KW - human KW - instrumentation KW - interventional radiology KW - materials KW - materials testing KW - methodology KW - physician KW - radiation injury KW - radiation protection KW - radiation scattering KW - Equipment Design KW - Equipment Failure Analysis KW - Humans KW - Manufactured Materials KW - Materials Testing KW - Physicians KW - Radiation Injuries KW - Radiation Protection KW - Radiography, Interventional KW - Scattering, Radiation AB - Purpose: To measure the attenuation effectiveness and minimize the weight of new non-Pb radiation shielding materials used for radiation protection by interventional radiology (IR) physicians, to compare the accuracy of the different standard measurement geometries of these materials, and to determine x-ray qualities that correspond to the scattered radiation that IR physicians typically encounter. Methods: Radiation attenuation capabilities of non-Pb materials were investigated. Typically, most studies of non-Pb materials have focused on the attenuating properties of metal powders. In this study, layers of materials incorporating non-Pb powdered compounds such as Bi2O 3, Gd2O3, and BaSO4 were measured individually, as bilayers, and as a Bi2O3-loaded hand cream. Attenuation measurements were performed in narrow-beam (fluorescence excluded) and broad beam (fluorescence included) geometries, demonstrating that these different geometries provided significantly different results. The Monte Carlo (MC) program EGSnrc was used to calculate the resulting spectra after attenuation by radiation shielding materials, and scattered x-ray spectra after 90° scattering of eight ASTM Standard primary x-ray beams. Surrogate x-ray qualities that corresponded to these scattered spectra were tabulated. Results: Radiation shielding materials incorporating Bi2O3 were found to provide equivalent or superior attenuation compared with commercial Pb-based and non-Pb materials across the 60-130 kVp energy range. Measurements were made for single layers of the Bi2O3 compound and for bilayers where the ordering was low atomic number (Z) layer closest to x-ray sourcehigh Z (Bi2O3) layer farthest from the x-ray source. Narrow-beam Standard test methods which do not include the contribution from fluorescence overestimated the attenuating capabilities of Pb and non-Pb materials. Measurements of a newly developed, quick-drying, and easily removable Bi2O3-loaded hand cream demonstrated better attenuation capabilities than commercial Bi2O3-loaded gloves. Scattered radiation measurements and MC simulations illustrated that the spectra resulting from 90° scattering of primary x-ray beam qualities can be approximated by surrogate x-ray qualities which are more representative of the radiation actually encountered by IR physicians. A table of surrogate qualities of the eight ASTM F2547-06 Standard qualities was compiled. Conclusions: New non-Pb compound materials, particularly single layers or bilayers incorporating Bi2O3, can reduce the weight of radiation protection materials while providing equivalent or better protection compared to Pb-based materials. Attenuation measurements in geometries that exclude the contribution from fluorescence substantially underestimate the quantity of transmitted radiation. A new Bi2O3-loaded hand cream demonstrated a novel and effective approach for hand protection. Standard testing protocols for radiation protection materials used by IR physicians specify a wider kVp range than is necessary. A more realistic range would acknowledge the lower kVp resulting from scatter and allow IR physicians to confidently utilize lighter-weight materials while still receiving adequate protection. Standards protocols incorporating the adjustments described in this work would maintain the safety of IR personnel and lessen the physical repercussions of long hours wearing unnecessarily heavy radiation protection garments. © 2012 American Association of Physicists in Medicine. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9bb21421-a952-4a2f-92a9-deee737ef310 ER - TY - JOUR TI - An analysis of the rapidly rotating Bp star HD 133880 DO - 10.1111/j.1365-2966.2012.20881.x AU - Bailey, J.D. AU - Grunhut, J. AU - Shultz, M. AU - Wade, G. AU - Landstreet, J.D. AU - Bohlender, D. AU - Lim, J. AU - Wong, K. AU - Drake, S. AU - Linsky, J. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 423 IS - 1 SP - 328 EP - 343 AB - HD 133880 is a rapidly rotating chemically peculiar B-type (Bp) star (vsini≃ 103kms -1) and is host to one of the strongest magnetic fields of any Ap/Bp star. A member of the Upper Centaurus Lupus association, it is a star with a well-determined age of 16Myr. 12 new spectra, four of which are polarimetric, obtained from the FEROS, ESPaDOnS and HARPS instruments, provide sufficient material from which to re-evaluate the magnetic field and obtain a first approximation to the atmospheric abundance distributions of He, O, Mg, Si, Ti, Cr, Fe, Ni, Pr and Nd. An abundance analysis was carried out using zeeman, a program which synthesizes spectral line profiles for stars with permeating magnetic fields. The magnetic field structure was characterized by a colinear multipole expansion from the observed variations of the longitudinal and surface fields with rotational phase. Both magnetic hemispheres are clearly visible during the stellar rotation, and thus a three-ring abundance distribution model encompassing both magnetic poles and magnetic equator with equal spans in colatitude was adopted. Using the new magnetic field measurements and optical photometry together with previously published data, we refine the period of HD 133880 to P= 0.877476 ± 0.000009d. Our simple axisymmetric magnetic field model is based on a predominantly quadrupolar component that roughly describes the field variations. Using spectrum synthesis, we derived mean abundances for O, Mg, Si, Ti, Cr, Fe and Pr. All elements, except Mg, are overabundant compared to the Sun. Mg appears to be approximately uniform over the stellar surface, while all other elements are more abundant in the negative magnetic hemisphere than in the positive magnetic hemisphere. In contrast to most Ap/Bp stars which show an underabundance in O, in HD 133880 this element is clearly overabundant compared to the solar abundance ratio. In studying the Hα and Paschen lines in the optical spectra, we could not unambiguously detect information about the magnetosphere of HD 133880. However, radio emission data at both 3 and 6cm suggest that the magnetospheric plasma is held in rigid rotation with the star by the magnetic field and further supported against collapse by the rapid rotation. Subtle differences in the shapes of the optically thick radio light curves at 3 and 6cm suggest that the large-scale magnetic field is not fully axisymmetric at large distances from the star. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f2928717-07cf-44e3-96a9-e41b06cfaa4c ER - TY - JOUR TI - Metabolic consequences of hepatic steatosis in overweight and obese adolescents DO - 10.2337/dc11-1754 AU - Wicklow, B.A. AU - Wittmeier, K.D.M. AU - MacIntosh, A.C. AU - Sellers, E.A.C. AU - Ryner, L. AU - Serrai, H. AU - Dean, H.J. AU - McGavock, J.M. T2 - Diabetes Care SN - 0149-5992 VL - 35 IS - 4 SP - 905 EP - 910 KW - alanine aminotransferase KW - aspartate aminotransferase KW - glucose KW - high density lipoprotein KW - low density lipoprotein KW - triacylglycerol KW - adolescent KW - adult KW - article KW - body fat KW - cardiorespiratory fitness KW - controlled study KW - cross-sectional study KW - disease association KW - dysglycemia KW - dyslipidemia KW - fatty liver KW - female KW - fitness KW - glucose blood level KW - glucose intolerance KW - human KW - insulin blood level KW - insulin release KW - insulin sensitivity KW - intraabdominal fat KW - major clinical study KW - male KW - metabolic syndrome X KW - non insulin dependent diabetes mellitus KW - obesity KW - outcome assessment KW - physical activity KW - prevalence KW - risk factor KW - triacylglycerol blood level KW - waist circumference KW - Adolescent KW - Body Fat Distribution KW - Case-Control Studies KW - Cross-Sectional Studies KW - Diabetes Mellitus, Type 2 KW - Fatty Liver KW - Female KW - Humans KW - Insulin Resistance KW - Lipids KW - Male KW - Obesity KW - Overweight KW - Risk Factors AB - OBJECTIVE - To test the hypothesis that hepatic steatosis is associated with risk factors for type 2 diabetes in overweight and obese youth, mediated by cardiorespiratory fitness. RESEARCH DESIGN AND METHODS - This was a cross-sectional study comparing insulin sensitivity between 30 overweight and obese adolescents with hepatic steatosis, 68 overweight and obese adolescents without hepatic steatosis, and 11 healthy weight adolescents without hepatic steatosis. Cardiorespiratory fitness was determined by a graded maximal exercise test on a cycle ergometer. Secondary outcomes included presence of metabolic syndrome and glucose response to a 75-g oral glucose challenge. RESULTS - The presence of hepatic steatosis was associated with 55%lower insulin sensitivity (P = 0.02) and a twofold greater prevalence of metabolic syndrome (P = 0.001). Differences in insulin sensitivity (3.5 vs. 4.5 mU · kg -1 · min -1, P = 0.03), prevalence of metabolic syndrome (48 vs. 20%, P = 0.03), and glucose area under the curve (816 vs. 710, P = 0.04) remained between groups after matching for age, sex, and visceral fat. The association between hepatic steatosis and insulin sensitivity (β = -0.24, t = -2.29, P < 0.025), metabolic syndrome (β = -0.54, t = -5.8, P < 0.001), and glucose area under the curve (β = 0.33, t = 3.3, P < 0.001) was independent of visceral and whole-body adiposity. Cardiorespiratory fitness was not associated with hepatic steatosis, insulin sensitivity, or presence of metabolic syndrome. CONCLUSIONS - Hepatic steatosis is associated with type 2 diabetes risk factors independent of cardiorespiratory fitness, whole-body adiposity, and visceral fat mass. © 2012 by the American Diabetes Association. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3806e42f-7d2a-457a-9023-5b85297fd997 ER - TY - JOUR TI - Vimentin participates in microglia activation and neurotoxicity in cerebral ischemia DO - 10.1111/j.1471-4159.2012.07823.x AU - Jiang, S.X. AU - Slinn, J. AU - Aylsworth, A. AU - Hou, S.T. T2 - Journal of Neurochemistry SN - 0022-3042 VL - 122 IS - 4 SP - 764 EP - 774 KW - lipopolysaccharide KW - tumor necrosis factor KW - vimentin KW - animal cell KW - animal experiment KW - animal model KW - animal tissue KW - article KW - brain infarction size KW - brain ischemia KW - cell activation KW - cell isolation KW - controlled study KW - gene deletion KW - gene expression regulation KW - gene overexpression KW - immunofluorescence KW - in vitro study KW - in vivo study KW - microglia KW - mouse KW - neuroprotection KW - neurotoxicity KW - nonhuman KW - priority journal KW - protein analysis KW - protein expression KW - protein function KW - signal transduction KW - Animals KW - Blotting, Western KW - Brain KW - Brain Ischemia KW - Cell Separation KW - Fluorescent Antibody Technique, Indirect KW - Image Processing, Computer-Assisted KW - In Situ Nick-End Labeling KW - Infarction, Middle Cerebral Artery KW - Ischemic Attack, Transient KW - Lipopolysaccharides KW - Macrophage Activation KW - Mice KW - Mice, Inbred C57BL KW - Mice, Knockout KW - Microglia KW - Microscopy, Confocal KW - Nervous System Diseases KW - Plasmids KW - Reperfusion Injury KW - Tetracycline KW - Vimentin AB - Microglia are the 'immune cells' of the brain and their activation plays a vital role in the pathogenesis of many neurodegenerative diseases. Activated microglia produce high levels of pro-inflammatory factors, such as TNFα, causing neurotoxicity. Here we show that vimentin played a key role in controlling microglia activation and neurotoxicity during cerebral ischemia. Deletion of vimentin expression significantly impaired microglia activation in response to LPS in vitro and transient focal cerebral ischemia in vivo. Reintroduction of the functional vimentin gene back into vimentin knockout microglia restored their response to LPS. More importantly, impairment of microglia activation significantly protected brain from cerebral ischemia-induced neurotoxicity. Collectively, we demonstrate a previously unknown function of vimentin in controlling microglia activation. Microglia activation plays an important role in many neurodegenerative diseases. Here we show that impaired vimentin expression significantly reduced microglia activation in response to LPS in vitro and cerebral ischemia in vivo. These studies demonstrate a unknown function of vimentin in controlling microglia activation and neurotoxicity during cerebral ischemia. © 2012 National Research Council Canada & The Authors. Journal of Neurochemistry © 2012 International Society for Neurochemistry. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 23ce368c-8f5d-4fc9-8fdf-b75ee8a7cbf9 ER - TY - JOUR TI - Procedure for direct measurement of general quantum states using weak measurement DO - 10.1103/PhysRevLett.108.070402 AU - Lundeen, J.S. AU - Bamber, C. T2 - Physical Review Letters SN - 0031-9007 VL - 108 IS - 7 SP - 70402 KW - Density matrix KW - Direct measurement KW - In-situ KW - Mixed state KW - Operational definition KW - Quantum state KW - Weak measurements KW - Measurements KW - Quantum optics KW - Quantum theory AB - Recent work by Lundeen et al. directly measured the wave function by weakly measuring a variable followed by a normal (i.e., "strong") measurement of the complementary variable. We generalize this method to mixed states by considering the weak measurement of various products of these observables, thereby providing the density matrix an operational definition in terms of a procedure for its direct measurement. The method only requires measurements in two bases and can be performed in situ, determining the quantum state without destroying it. © 2012 American Physical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 80f0c646-4dab-4aeb-bf05-8897d1d06d11 ER - TY - JOUR TI - Laser cladding of high-performance CPM tool steels on hardened H13 hot-work tool steel for automotive tooling applications AU - Chen, J. AU - Xue, L. T2 - TMS Annual Meeting T3 - 141st Annual Meeting and Exhibition, TMS 2012, 11 March 2012 through 15 March 2012, Orlando, FL SN - 9781118296073 VL - 1 SP - 11 EP - 18 KW - AISI H13 KW - H13 tool steel KW - Tooling KW - Carbides KW - Chromium KW - Hardening KW - Interfaces (materials) KW - Laser cladding KW - Vanadium AB - This paper summarizes our work on laser cladding of high-vanadium carbide CPM tool steels (3V, 9V and 15V) onto hardened chromium hot-work AISI H13 tool steel with a hardness of HRc 50-55 in order to substantially enhance abrasive wear resistance, which provides a great potential for fabricating high-performance automotive tooling at affordable cost. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d4b4feba-d6da-4d7a-b25d-5fb3a2ddfe49 ER - TY - JOUR TI - Experimental results on wavefront correction using the self-coherent camera DO - 10.1117/12.926586 AU - Mas, M. AU - Baudoz, P. AU - Mazoyer, J. AU - Galicher, R. AU - Rousset, G. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Ground-Based and Airborne Instrumentation for Astronomy IV, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491473 VL - 8446 SP - 844689 KW - Coronagraphy KW - High angular resolutions KW - High contrast imaging KW - Instrumentation KW - Wavefront correction KW - Aberrations KW - Astronomy KW - Cameras KW - Computer simulation KW - Detectors KW - Focusing KW - Speckle KW - Wavefronts AB - The Self-Coherent Camera is dedicated to the direct detection of exoplanets. This instrument can be used as a focal plane wavefront sensor to measure static aberrations that induce speckles on the detector, which prevents the detection of faint companions. The Self-Coherent Camera creates a reference beam in the Lyot stop pupil plane in order to spatially modulate the speckle pattern with Fizeau fringes. We can then estimate for wavefront aberrations upstream of the coronagraphic mask and correct for them using a deformable mirror. Currently, the Self-Coherent Camera is combined with a deformable mirror located in the pupil plane upstream of a Four-Quadrant Phase Mask Coronagraph. In this paper, we present the formalism that explains how the Self-Coherent Camera encodes speckles and how we estimate the wavefront aberrations directly from the science image. We present numerical simulation results on speckle suppression in the focal plane. Then, we give experimental results on wavefront correction on our optical bench using a 32x32 actuators deformable mirror. We show that we can improve the contrast in the focal plane by a factor of more than 100 in the PSF wings up to 12λ/D. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 257cd4f2-acba-45fa-9f8c-7b95fbc36fb3 ER - TY - JOUR TI - Spin-forbidden Helium I transition rates DO - 10.1088/1742-6596/388/15/152019 AU - Morton, D.C. AU - Drake, G.W.F. T2 - Journal of Physics: Conference Series T3 - 27th International Conference on Photonic, Electronic and Atomic Collisions, ICPEAC 2011, 27 July 2011 through 2 August 2011, Belfast SN - 1742-6588 VL - 388 IS - PART 15 SP - 152019 KW - Spin orbits KW - Spin other orbits KW - Transition rates KW - Physics KW - Helium AB - We have calculated spin-forbidden transition rates in neutral helium using the spin-orbit and spin-other-orbit Breit-Pauli operators. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 73a360f1-1303-4489-b104-04e2f63174ec ER - TY - JOUR TI - Non-contact photoacoustic tomography and ultrasonography for tissue imaging AU - Rousseau, G. AU - Blouin, A. AU - Monchalin, J.-P. T2 - Biomedical Optics Express SN - 2156-7085 VL - 3 IS - 1 SP - 16 EP - 25 KW - Biological tissues KW - Biomedical imaging KW - Chicken breast KW - Confocal Fabry Perot interferometer KW - Differential configuration KW - Ex-vivo KW - Laser exposure KW - Laser ultrasonics KW - Non-contact KW - Optical detection KW - Photoacoustic tomography KW - Potential applications KW - Safety limits KW - Scope of application KW - Shaped laser pulse KW - Small animal imaging KW - Tissue imaging KW - Animals KW - Bioacoustics KW - Laser safety KW - Medical imaging KW - Tissue KW - Ultrasonic applications KW - Ultrasonic transducers KW - Ultrasonics KW - Ultrasonography KW - Photoacoustic effect KW - Animalia KW - Columba AB - The detection of ultrasound in photoacoustic tomography (PAT) and ultrasonography (US) usually relies on ultrasonic transducers in contact with the biological tissue. This is a major drawback for important potential applications such as surgery and small animal imaging. Here we report the use of remote optical detection, as used in industrial laser-ultrasonics, to detect ultrasound in biological tissues. This strategy enables non-contact implementation of PAT and US without exceeding laser exposure safety limits. The method uses suitably shaped laser pulses and a confocal Fabry-Perot interferometer in differential configuration to reach quantum-limited sensitivity. Endogenous and exogenous inclusions exhibiting optical and acoustic contrasts were detected ex vivo in chicken breast and calf brain specimens. Inclusions down to 0.5 mm in size were detected at depths well exceeding 1 cm. The method could significantly expand the scope of applications of PAT and US in biomedical imaging. © 2011 Optical Society of America. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1c6888d7-f239-4978-8996-2ce57068dd04 ER - TY - JOUR TI - Bacteriophages with the ability to degrade uropathogenic Escherichia Coli biofilms DO - 10.3390/v4040471 AU - Chibeu, A. AU - Lingohr, E.J. AU - Masson, L. AU - Manges, A. AU - Harel, J. AU - Ackermann, H.-W. AU - Kropinski, A.M. AU - Boerlin, P. T2 - Viruses SN - 1999-4915 VL - 4 IS - 4 SP - 471 EP - 487 KW - amoxicillin plus clavulanic acid KW - ampicillin KW - cefoxitin KW - ceftiofur KW - ceftriaxone KW - chloramphenicol KW - ciprofloxacin KW - cotrimoxazole KW - kanamycin KW - nalidixic acid KW - streptomycin KW - sulfafurazole KW - tetracycline KW - antibiotic resistance KW - antibiotic sensitivity KW - article KW - bacterial genome KW - bacterial strain KW - bacterial virulence KW - bacteriophage KW - bacterium isolate KW - biofilm KW - controlled study KW - DNA sequence KW - genetic variability KW - nonhuman KW - nucleotide sequence KW - serotype KW - uropathogenic Escherichia coli KW - Anti-Bacterial Agents KW - Bacteriolysis KW - Biofilms KW - Coliphages KW - DNA, Viral KW - Female KW - Genome, Viral KW - Genotype KW - Humans KW - Microbial Sensitivity Tests KW - Molecular Sequence Data KW - Sequence Analysis, DNA KW - Serotyping KW - Uropathogenic Escherichia coli KW - Bacteria (microorganisms) KW - Escherichia coli AB - Escherichia coli-associated urinary tract infections (UTIs) are among the most common bacterial infections in humans. UTIs are usually managed with antibiotic therapy, but over the years, antibiotic-resistant strains of uropathogenic E. coli (UPEC) have emerged. The formation of biofilms further complicates the treatment of these infections by making them resistant to killing by the host immune system as well as by antibiotics. This has encouraged research into therapy using bacteriophages (phages) as a supplement or substitute for antibiotics. In this study we characterized 253 UPEC in terms of their biofilm-forming capabilities, serotype, and antimicrobial resistance. Three phages were then isolated (vB_EcoP_ACG-C91, vB_EcoM_ACG-C40 and vB_EcoS_ACG-M12) which were able to lyse 80.5% of a subset (42) of the UPEC strains able to form biofilms. Correlation was established between phage sensitivity and specific serotypes of the UPEC strains. The phages' genome sequences were determined and resulted in classification of vB_EcoP_ACG-C91 as a SP6likevirus, vB_EcoM_ACG-C40 as a T4likevirus and vB_EcoS_ACG-M12 as T1likevirus. We assessed the ability of the three phages to eradicate the established biofilm of one of the UPEC strains used in the study. All phages significantly reduced the biofilm within 2-12 h of incubation. © 2012 by the authors; licensee MDPI, Basel, Switzerland. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cd31fc33-a62c-4a9a-9f83-652ba19b6aaa ER - TY - JOUR TI - Alessi 95 and the short-period Cepheid SU Cassiopeiae DO - 10.1111/j.1365-2966.2012.20806.x AU - Turner, D.G. AU - Majaess, D.J. AU - Lane, D.J. AU - Balam, D.D. AU - Gieren, W.P. AU - Storm, J. AU - Forbes, D.W. AU - Havlen, R.J. AU - Alessi, B. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 422 IS - 3 SP - 2501 EP - 2509 AB - The parameters for the newly discovered open cluster Alessi 95 are established on the basis of available photometric and spectroscopic data, in conjunction with new observations. Colour excesses for spectroscopically observed B- and A-type stars near SU Cas follow a reddening relation described by E(U-B)/E(B-V) = 0.83 + 0.02E(B-V), implying a value of R=A V/E(B-V) ≃ 2.8 for the associated dust. Alessi 95 has a mean reddening of E(B-V)(B0) = 0.35 ± 0.02s.e., an intrinsic distance modulus of V 0-M V= 8.16 ± 0.04s.e. (±0.21s.d.), d= 429 ± 8pc, and an estimated age of 10 8.2yr from zero-age main sequence (ZAMS) fitting of available UBV, CCD BV, NOMAD, and Two Micron All Sky Survey JHK s observations of cluster stars. SU Cas is a likely cluster member, with an inferred space reddening of E(B-V) = 0.33 ± 0.02 and a luminosity of 〈M V〉=-3.15 ± 0.07s.e., consistent with overtone pulsation (P FM= 2.75d), as also implied by the Cepheid's light-curve parameters, rate of period increase and Hipparcos parallaxes for cluster stars. There is excellent agreement of the distance estimates for SU Cas inferred from cluster ZAMS fitting, its pulsation parallax derived from the infrared surface brightness technique and Hipparcos parallaxes, which all agree to within a few per cent. © 2012 The Authors. Monthly Notices of the Royal Astronomical Society © 2012 RAS. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fbf2c200-8554-4052-ad83-015125ae9c0b ER - TY - JOUR TI - More on the narrowing of impact broadened radio recombination lines at high principal quantum number DO - 10.1007/s10509-012-1042-5 AU - Bell, M.B. T2 - Astrophysics and Space Science SN - 0004-640X VL - 340 IS - 1 SP - 127 EP - 131 AB - Recently Alexander and Gulyaev have suggested that the apparent decrease in impact broadening of radio recombination lines seen at high principal quantum number n may be a product of the data reduction process, possibly resulting from the presence of noise on the telescope spectra that is not present on the calculated comparison spectra. This is an interesting proposal. However, there are serious problems with their analysis that need to be pointed out. Perhaps the most important of these is the fact that for principal quantum numbers below n=200, where the widths are not in question, their processed generated profile widths do not fit the widths of the processed lines obtained at the telescope. After processing, the halfwidths of the generated and telescope profiles must agree below n=200 if we are to believe that the processed generated linewidths above n=200 are meaningful. Theirs do not. Furthermore, we find that after applying the linewidth reduction factors found by Alexander and Gulyaev for their noise added profiles to our generated profiles to simulate their noise adding effect, the processed widths we obtain still do not come close to explaining the narrowing seen in the telescope lines for n values in the range 200 < n < 250. It is concluded that what is needed to solve this mystery is a completely new approach using a different observing technique instead of simply a further manipulation of the frequency-switched data. © 2012 Springer Science+Business Media B.V. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3176f40b-94af-4da5-a0c0-bc25b52fca33 ER - TY - JOUR TI - Performance of dynamic azimuthing podded propulsor DO - 10.3233/ISP-2012-0080 AU - Akinturk, A. AU - Islam, M.F. AU - Veitch, B. AU - Liu, P. T2 - International Shipbuilding Progress SN - 0020-868X VL - 59 IS - 1-Feb SP - 83 EP - 106 KW - Azimuthing KW - Comparative studies KW - Experimental studies KW - Global forces KW - Open water KW - Order polynomials KW - Performance coefficients KW - Podded propulsors KW - Propulsive performance KW - Propulsors KW - Rotational speed KW - Static and dynamic KW - Thrust and torques KW - Loading KW - Uncertainty analysis KW - Propellers AB - This paper presents results and analyses of an experimental study into the effects of static and dynamic azimuthing conditions on the propulsive characteristics of a puller podded unit in open water. The model propulsor was instrumented to measure thrust and torque of the propeller, three orthogonal forces and moments on the unit, rotational speed of the propeller, azimuthing angle and azimuthing rate. The model was first tested over a range of advance coefficients at various static azimuthing angles in the range of-180° to 180°. These tests were followed by tests in which the azimuthing angle was varied dynamically at certain azimuthing rate and propeller rotational speed. A comparative study of the performance coefficients at static and dynamic azimuthing conditions in the range of-180° to 180° is presented. The performance coefficients of the propeller and the pod unit showed a strong dependence on the propeller loading and azimuthing angle. The coefficients in static azimuthing conditions fit well with a 10th order polynomial fit of the data obtained in the dynamic azimuthing condition in the corresponding azimuthing angles and advance coefficient. An uncertainty analysis of the measurements is also presented. © 2012-IOS Press and the authors. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 71ddf865-3733-42bf-88f7-d60aeceda361 ER - TY - JOUR TI - Germline ablation of SMUG1 DNA glycosylase causes loss of 5-hydroxymethyluracil-and UNG-backup uracil-excision activities and increases cancer predisposition of Ung-/-Msh2-/- mice DO - 10.1093/nar/gks259 AU - Kemmerich, K. AU - Dingler, F.A. AU - Rada, C. AU - Neuberger, M.S. T2 - Nucleic Acids Research SN - 0305-1048 VL - 40 IS - 13 SP - 6016 EP - 6025 KW - 5 hydroxymethyluracil KW - DNA glycosyltransferase KW - protein SMUG1 KW - protein UNG KW - unclassified drug KW - uracil KW - animal cell KW - animal tissue KW - article KW - cancer susceptibility KW - controlled study KW - deamination KW - embryo KW - enzyme activity KW - gene KW - gene inactivation KW - knockout mouse KW - male KW - mouse KW - MSH2 gene KW - nonhuman KW - priority journal KW - SMUG1 gene KW - ung gene KW - Animals KW - beta-Galactosidase KW - Cell Line KW - DNA Repair KW - Fibroblasts KW - Fluorouracil KW - Gene Targeting KW - Genetic Predisposition to Disease KW - Longevity KW - Mice KW - Mice, Inbred C57BL KW - Mice, Knockout KW - MutS Homolog 2 Protein KW - Neoplasms, Experimental KW - Pentoxyl KW - Thymidine KW - Uracil-DNA Glycosidase KW - Mammalia KW - Mus AB - Deamination of cytosine (C), 5-methylcytosine (mC) and 5- hydroxymethylcytosine (hmC) occurs spontaneously in mammalian DNA with several hundred deaminations occurring in each cell every day. The resulting potentially mutagenic mispairs of uracil (U), thymine (T) or 5-hydroxymethyluracil (hmU) with guanine (G) are substrates for repair by various DNA glycosylases. Here,weshowthat targetedinactivation of the mouse Smug1 DNA glycosylase gene is sufficient to ablate nearly all hmU-DNA excision activity as judged by assay of tissue extracts from knockout mice as well as by the resistance of their embryo fibroblasts to 5-hydroxymethyldeoxyuridine toxicity. Inactivation of Smug1 when combined with inactivation of the Ung uracil-DNA glycosylase gene leads to a loss of nearly all detectable uracil excision activity. Thus, SMUG1 is the dominant glycosylase responsible for hmU-excision in mice as well as the major UNG-backup for U-excision. Both Smug1-knockout and Smug1/Ung-double knockout mice breed normally and remain apparently healthy beyond 1 year of age. However, combined deficiency in SMUG1 and UNG exacerbates the cancer predisposition of Msh2-/- mice suggesting that when both base excision and mismatch repair pathways are defective, the mutagenic effects of spontaneous cytosine deamination are sufficient to increase cancer incidence but do not preclude mouse development. © 2012 The Author(s). DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d041f676-5a4e-4352-b0d3-490588012617 ER - TY - CHAP TI - Correction of instrumental mass discrimination for isotope ratio determination with multi-collector inductively coupled plasma mass spectrometry DO - 10.1002/9783527650484.ch5 AU - Meija, Juris AU - Yang, Lu AU - Mester, Zoltán AU - Sturgeon, Ralph E. T2 - Isotopic Analysis: Fundamentals and Applications Using ICP-MS SN - 9783527328963 SP - 113 EP - 137 KW - Inductively coupled plasma mass spectrometry; multi-collector; isotope ratio; instrumental mass discrimination; calibration; double spike. uncertainty DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fbfef87a-d857-4293-8c02-71e489f3b1ca ER - TY - JOUR TI - π/2-Angle yao graphs are spanners DO - 10.1142/S0218195912600047 AU - Bose, P. AU - Damian, M. AU - DouÏeb, K. AU - O'Rourke, J. AU - Seamone, B. AU - Smid, M. AU - Wuhrer, S. T2 - International Journal of Computational Geometry and Applications SN - 0218-1959 VL - 22 IS - 1 SP - 61 EP - 82 AB - We show that the Yao graph Y 4 in the L 2 metric is a spanner with stretch factor 8√2(26 + 23√2 ). Enroute to this, we also show that the Yao graph Y ∞4 in the L ∞ metric is a plane spanner with stretch factor 8. © 2012 World Scientific Publishing Company. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5635c28f-a824-4d7d-9ad8-4095db5153e6 ER - TY - JOUR TI - The effect of nozzle shape and configuration on bubble formation in a liquid cross flow DO - 10.1115/FEDSM2012-72313 AU - Jobehdar, M.H. AU - Gadallah, A.H. AU - Siddiqui, K. AU - Chishty, W.A. T2 - American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FEDSM T3 - ASME 2012 Fluids Engineering Division Summer Meeting, FEDSM 2012 Collocated with the ASME 2012 Heat Transfer Summer Conf. and the ASME 2012 10th International Conference on Nanochannels, Microchannels, and M, FEDSM 2012, 8 July 2012 through 12 July 2012, Rio Grande SN - 0888-8116 SN - 9780791844755 VL - 1 IS - PARTS A AND B SP - 1205 EP - 1209 KW - Bubble velocities KW - Cross-flow direction KW - Gas and liquid flows KW - Gas to liquids KW - High speed imaging KW - Image processing algorithm KW - Low-intensity KW - Two-dimensional profiles KW - Bubble formation KW - Chemical plants KW - Flow rate KW - Heat transfer KW - High speed cameras KW - Image processing KW - Light sources KW - Microchannels KW - Nozzles KW - Two dimensional KW - Liquids AB - Gas injection into a liquid cross flow from a nozzle causes bubble formations which have potential applications in industry such as chemical plants, waste water treatment and bio- and nuclear-reactors. The purpose of this study is to experimentally investigate the effects of nozzle shape and configuration with respect to the liquid cross-flow direction, on the bubbly flow characteristics such as bubble formation, detached bubble size and frequency at different gas and liquid flow rates. The experiments were conducted in a Plexiglas two-dimensional rig using a high speed camera. High speed imaging and an image processing algorithm were used to track each individual bubble and to quantify the bubble growth as well as the detachment frequency and the bubble velocity. Back light shadowgraphy which utilizes a low intensity diffuse light source to illuminate the background was used to image bubbles. Nozzles were mounted in the test section which was designed such that the flow in this section has a two-dimensional profile. The results showed that the bubble size increases with an increase in GLR (gas to liquid flow rates ratio). Furthermore, the bubble formations and detached bubble size were strongly influenced by the nozzle shape and configuration. Copyright © 2012 by ASME. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9e9acfb0-64c2-432e-b952-75b4acaa48c5 ER - TY - JOUR TI - Use of filler wire for laser welding of Ti-6Al-4V DO - 10.1179/1879139512Y.0000000016 AU - Kabir, A.S.H. AU - Cao, X. AU - Wanjara, P. AU - Cuddy, J. AU - Birur, A. AU - Medraj, M. T2 - Canadian Metallurgical Quarterly SN - 0008-4433 VL - 51 IS - 3 SP - 320 EP - 327 KW - Base metals KW - Bead geometry KW - Continuous Wave KW - Excellent corrosion resistances KW - Filler addition KW - Filler wire KW - Fusion zones KW - Gap widths KW - High specific strength KW - Joint gap KW - Laser welds KW - Microindentation hardness KW - ND : YAG lasers KW - Parent metal KW - Sheet thickness KW - Thick sheets KW - Ti alloys KW - Ti-6al-4v KW - Underfills KW - Aerospace industry KW - Aluminum KW - Corrosion resistance KW - Hardness KW - Laser beam welding KW - Mechanical properties KW - Microstructure KW - Titanium alloys KW - Welds KW - Neodymium lasers AB - Owing to the high specific strength and excellent corrosion resistance, Ti-6Al-4V has been widely applied in aerospace industries. In this study, the welding performance of 3·2 and 5·1 mm thick Ti-6Al-4V sheets was studied using a 4 kW continuous wave Nd:YAG laser. It is found that the use of filler wire, matching the parent metal composition, can bridge the joint gap and produce full penetrated welds up to a width of 0·6 mm without cracking. The laser welds were characterised in terms of the bead geometry, defects, microstructures and hardness. With increasing joint gap, the percent porosity area increased, reaching just over 1% of the fusion zone area at a gap width of 0·6 mm for the 3·2 and 5·1 mm thick sheets. The maximum underfill depth in the Ti-6Al-4V laser welds was about 5%or 7%of the sheet thickness for the 3·2 and5·2 mmthick materials, respectively, meeting the AWS D17-1 specification. The microindentation hardness was maximum in the fusion zone and sharply decreased through the heat affected zone until reaching the base metal value. © 2012 Crown in Right of Canada. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2a10c64b-10e6-4794-b88e-fcdb6fc388ff ER - TY - JOUR TI - Luminosities of barred and unbarred S0 galaxies DO - 10.1088/0004-637X/754/1/68 AU - Van Den Bergh, S. T2 - The Astrophysical Journal SN - 0004-637X VL - 754 IS - 1 SP - 68 AB - Lenticular galaxies with M B < -21.5 are almost exclusively unbarred, whereas both barred and unbarred objects occur at fainter luminosity levels. This effect is observed both for objects classified in blue light, and for those that were classified in the infrared. This result suggests that the most luminous (massive) S0 galaxies find it difficult to form bars. As a result, the mean luminosity of unbarred lenticular galaxies in both B and IR light is observed to be 0.4mag brighter than that of barred lenticulars. A small contribution to the observed luminosity difference that is found between SA0 and SB0 galaxies may also be due to the fact that there is an asymmetry between the effects of small classification errors on SA0 and SB0 galaxies. An elliptical (E) galaxy might be misclassified as a lenticular (S0) or an S0 as an E. However, an E will never be misclassified as an SB0, nor will an SB0 ever be called an E. This asymmetry is important because E galaxies are typically twice as luminous as S0 galaxies. The present results suggest that the evolution of luminous lenticular galaxies may be closely linked to that of elliptical galaxies, whereas fainter lenticulars might be more closely associated with ram-pressure stripped spiral galaxies. Finally, it is pointed out that fine details of the galaxy formation process might account for some of the differences between the classifications of the same galaxy by individual competent morphologists. © 2012. The American Astronomical Society. All rights reserved.. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 64c42f06-0533-46ec-b3c9-f0279d82b57f ER - TY - JOUR TI - Continuous-wave operation of type-I GaSb-based narrow ridge waveguide lasers near 3254nm AU - Gupta, J.A. AU - Barrios, P.J. AU - Bezinger, A. AU - Waldron, P. T2 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012 T3 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012, 6 May 2012 through 11 May 2012, San Jose, CA SN - 9781467318396 SP - 6325436 KW - Active regions KW - Continuous wave modes KW - Continuous wave operation KW - InGaAsSb KW - Light output KW - Ridge waveguide lasers KW - Gallium alloys KW - Lasers KW - Ridge waveguides KW - Quantum well lasers AB - Narrow ridge waveguide (5um) laser diodes were fabricated using type-I InGaAsSb/AlInGaAsSb quantum well active regions on GaSb. The devices operate in continuous-wave mode near 3254nm with a total light output of 7.4mW at 20°C (uncoated facets). © 2012 OSA. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : eac845fa-4512-40c6-adac-5e16dbd1a373 ER - TY - JOUR TI - In vivo open-bore MRI reveals region- and sub-arc-specific lengthening of the unloaded human posterior cruciate ligament DO - 10.1371/journal.pone.0048714 AU - King, A.J. AU - Deng, Q. AU - Tyson, R. AU - Sharp, J.C. AU - Matwiy, J. AU - Tomanek, B. AU - Dunn, J.F. T2 - PLoS ONE SN - 1932-6203 VL - 7 IS - 11 SP - e48714 KW - adult KW - article KW - controlled study KW - eye tracking KW - female KW - human KW - human experiment KW - human tissue KW - image analysis KW - image reconstruction KW - in vivo study KW - knee KW - knee extension KW - knee function KW - knee ligament KW - ligament lengthening KW - male KW - movement (physiology) KW - musculoskeletal system parameters KW - normal human KW - nuclear magnetic resonance imaging KW - nuclear magnetic resonance scanner KW - open bore nuclear magnetic resonance imaging KW - partition coefficient KW - soft tissue KW - videorecording KW - Adult KW - Biomechanics KW - Female KW - Humans KW - Knee KW - Knee Joint KW - Magnetic Resonance Imaging KW - Posterior Cruciate Ligament KW - Video Recording AB - Open-bore MRI scanners allow joint soft tissue to be imaged over a large, uninterrupted range of flexion. Using an open-bore scanner, 3D para-sagittal images of the posterior cruciate ligament (PCL) were collected from seven healthy subjects in unloaded, recumbent knee extension and flexion. PCL length was measured from one 2D MRI slice partition per flexion angle, per subject. The anterior surface of the PCL lengthened significantly between extension and flexion (p<0.001). Conversely, the posterior surface did not. Changes were not due to the PCL moving relative to the 2D slice partition; measurements made from 3D reconstructions, which compensated for PCL movement, did not differ significantly from measurements made from 2D slice partitions. In a second experiment, videos of knee flexion were made by imaging two subjects at several flexion angles. Videos allowed soft tissue tracking; examples are included. In a third experiment, unloaded knees of seven healthy, recumbent subjects were imaged at extension and at 40°, 70°, 90°, 100°, 110° and 120° flexion. The distance between PCL attachments increased between extension and 100°, and then decreased (p<0.001). The anterior surface of the PCL lengthened over the flexion angles measured (p<0.01). The posterior surface of the PCL lengthened between extension and 40° and then shortened (p<0.001). Both attachment separation and anterior surface length increased dramatically between extension and 40°, but varied less afterwards. Results indicate that PCL dynamics differ between terminal extension and active function sub-arcs. Also, attachment separation cannot predict the lengthening of all parts of the PCL, nor can lengthening of one part of the PCL predict the lengthening of another part. A potential connection between lengthening and loading is discussed. We conclude that low-field MRI can assess ligament lengthening during flexion, and that the dynamics of the PCL for any given region and sub-arc should be measured directly. © 2012 King et al. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0ff28023-969b-4297-81b5-f94f80194a96 ER - TY - JOUR TI - A model of ice friction for an inclined incising slider AU - Lozowski, E.P. AU - Szilder, K. AU - Maw, S. T2 - Proceedings of the International Offshore and Polar Engineering Conference T3 - 22nd International Offshore and Polar Engineering Conference, ISOPE-2012, 17 June 2012 through 22 June 2012, Rhodes SN - 1098-6189 SN - 9781880653944 SP - 1243 EP - 1251 KW - Couette flows KW - Frictional melting KW - Ice friction KW - In-situ measurement KW - Model results KW - Sliding direction KW - Sliding velocities KW - Squeeze flow KW - Theory KW - Vertical plane KW - Friction KW - Lubrication KW - Models KW - Physics KW - Recreational facilities KW - Ice AB - The FAST 2.0 model of ice friction was developed for a vertically oriented speed skate. The model is therefore left-right symmetrical about a vertical plane parallel to the sliding direction. It describes ice friction at sliding velocities sufficiently high to produce a lubricating layer of meltwater, which completely separates the ice and slider surfaces. Friction results from ploughing a groove in the ice and from the shear stress in the lubricating Couette flow. The model takes into account frictional melting, heat conduction into the ice and the lateral squeeze flow of the lubricating liquid. Here we present a new, numerical model, FAST 2.0i, which calculates ice friction for an inclined runner that is incising into the ice. Specifically, we consider an inclined speed skate blade and we use it to predict the variation of ice friction during a typical skating stroke. The model results compare favorably with in situ measurements. Copyright © 2012 by the International Society of Offshore and Polar Engineers (ISOPE). DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8c6a6556-d3fc-4f87-b0cb-6aa5649b1077 ER - TY - JOUR TI - North American symposium on laser induced breakdown spectroscopy (NASLIBS): Introduction to feature issue DO - 10.1364/AO.51.0LIBS1 AU - Singh, J.P. AU - Almirall, J. AU - Sabsabi, M. AU - Miziolek, A.W. T2 - Applied Optics SN - 0003-6935 VL - 51 IS - 7 SP - LIBS1 EP - LIBS2 KW - editorial KW - environmental monitoring KW - equipment design KW - instrumentation KW - laser KW - methodology KW - organization KW - spectroscopy KW - Congresses as Topic KW - Environmental Monitoring KW - Equipment Design KW - Lasers KW - Spectrum Analysis KW - North American KW - Optics KW - Molecular physics AB - This feature issue highlights the topics of the 2011 North American Symposium on Laser Induced Breakdown Spectroscopy (NASLIBS). These include LIBS application to Security and Forensic, Biomedical and Environmental, Liquid Analysis and Fundamentals of LIBS, Instrumentation/Commercialization, Fusion with LIBS, and New Frontiers. © 2012 Optical Society of America. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9d28cd88-0cdb-4798-8a5d-d8ce2d04e7af ER - TY - JOUR TI - Brain tumor surgery with 3-dimensional surface navigation DO - 10.1227/NEU.0b013e31826a8a75 AU - Mert, A. AU - Buehler, K. AU - Sutherland, G.R. AU - Tomanek, B. AU - Widhalm, G. AU - Kasprian, G. AU - Knosp, E. AU - Wolfsberger, S. T2 - Neurosurgery SN - 0148-396X VL - 71 IS - SUPPL.2 SP - ons286 EP - ons294 KW - article KW - brain metastasis KW - brain size KW - brain tumor KW - cancer surgery KW - cavernoma KW - controlled study KW - glioma KW - human KW - intermethod comparison KW - major clinical study KW - meningioma KW - nuclear magnetic resonance imaging KW - preoperative evaluation KW - priority journal KW - three dimensional imaging KW - treatment planning KW - Algorithms KW - Brain Neoplasms KW - Humans KW - Imaging, Three-Dimensional KW - Neuronavigation KW - Software AB - BACKGROUND:: Precise lesion localization is necessary for neurosurgical procedures not only during the operative approach, but also during the preoperative planning phase. OBJECTIVE:: To evaluate the advantages of 3-dimensional (3-D) brain surface visualization over conventional 2-dimensional (2-D) magnetic resonance images for surgical planning and intraoperative guidance in brain tumor surgery. METHODS:: Preoperative 3-D brain surface visualization was performed with neurosurgical planning software in 77 cases (58 gliomas, 7 cavernomas, 6 meningiomas, and 6 metastasis). Direct intraoperative navigation on the 3-D brain surface was additionally performed in the last 20 cases with a neurosurgical navigation system. For brain surface reconstruction, patient-specific anatomy was obtained from MR imaging and brain volume was extracted with skull stripping or watershed algorithms, respectively. Three-dimensional visualization was performed by direct volume rendering in both systems. To assess the value of 3-D brain surface visualization for topographic lesion localization, a multiple-choice test was developed. To assess accuracy and reliability of 3-D brain surface visualization for intraoperative orientation, we topographically correlated superficial vessels and gyral anatomy on 3-D brain models with intraoperative images. RESULTS:: The rate of correct lesion localization with 3-D was significantly higher (P = .001, χ), while being significantly less time consuming (P < .001, χ) compared with 2-D images. Intraoperatively, visual correlation was found between the 3-D images, superficial vessels, and gyral anatomy. CONCLUSION:: The proposed method of 3-D brain surface visualization is fast, clinically reliable for preoperative anatomic lesion localization and patient-specific planning, and, together with navigation, improves intraoperative orientation in brain tumor surgery and is relatively independent of brain shift. © 2012 by the Congress of Neurological Surgeons. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 13d5ae09-1234-483a-bb04-b97e874ac2b9 ER - TY - JOUR TI - Comparison of the computational NMR chemical shifts of choline with the experimental data DO - 10.1088/1742-6596/341/1/012013 AU - Alcorn, C. AU - Cuperlovic-Culf, M. AU - Ghandi, K. T2 - Journal of Physics: Conference Series T3 - 25th High Performance Computing Symposium 2011, HPCS 2011, 15 June 2011 through 17 June 2011, Montreal, QC SN - 1742-6588 VL - 341 IS - 1 SP - 12013 KW - Atomic orbital KW - Biological markers KW - Correlation functionals KW - Diagnostic tools KW - Experimental data KW - Head groups KW - High performance computing systems KW - Methyl group KW - NMR chemical shifts KW - Optimized structures KW - Over-expression KW - Polarizable continuum model KW - Proton spectra KW - Solvent effects KW - Structural similarity KW - Continuum mechanics KW - Functional groups KW - Magnetic resonance spectroscopy KW - Quantum chemistry KW - Diseases AB - One of the main biological markers of the presence of cancer in living patients is an over-expression of total choline (tCho), which is the sum of free choline and its derivatives. 1H Magnetic Resonance Spectroscopy, or H-MRS, enables the quantification of tCho via its proton spectra, and thus has the potential to be a diagnostic tool for the presence of cancer and an accurate early indicator of the response of cancer to treatment. However, it remains difficult to quantify individual choline derivatives, since they share a large structural similarity ((CH 3) 3-N +-CH 2-CH 2-O-), of which the strongest signal detectable by MRS is that of the choline "head group": the three methyl groups bonded to the nitrogen. This work used ACENet, a high performance computing system, to attempt to model the NMR parameters of choline derivatives, with the focus of this report being free choline. Optimized structures were determined using Density Functional Theory and the B3LYP electron correlation functional. The Polarizable Continuum Model was used to evaluate solvent effects. The Gauge-Invariant Atomic Orbital method was found to be the superior method for calculating the NMR parameters of cholines. © IOP Publishing Ltd. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5d48104e-c959-4f96-8a71-602f913e5d75 ER - TY - JOUR TI - Application of single-domain antibodies in tumor histochemistry DO - 10.1007/978-1-61779-968-6-33 AU - Maik, K.T. AU - MacKenzie, C.R. T2 - Methods in Molecular Biology SN - 1064-3745 SN - 9781617799679 VL - 911 SP - 523 EP - 530 KW - carcinoembryonic antigen related cell adhesion molecule 6 KW - nanobody KW - pentabody ES1 KW - unclassified drug KW - antibody specificity KW - antigen expression KW - article KW - cancer tissue KW - embedding KW - human KW - human tissue KW - immunohistochemistry KW - immunoreactivity KW - lung carcinoma KW - priority journal KW - procedures KW - sensitivity and specificity KW - tissue microarray KW - tissue section KW - cytochemistry KW - metabolism KW - methodology KW - neoplasm KW - pathology KW - Histocytochemistry KW - Humans KW - Neoplasms KW - Single-Domain Antibodies AB - High avidity, pentameric, single-domain antibodies, oligomerized through the B subunit of verotoxin, are excellent immunohistochemical reagents. The resulting molecules are termed pentabodies. Here, we describe the immunostaining of tissue sections with ES1, a pentabody recognizing CEACAM6 which is overexpressed in several cancers. The advantages of pentabodies, compared to conventional antibody reagents, in immunohistochemical studies are highlighted. © 2012 Springer Science+Business Media, LLC. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6d43d3cb-6420-4f2a-a180-435d6c3f62c8 ER - TY - JOUR TI - Assessment of combustor working environments DO - 10.1155/2012/217463 AU - Jiang, L. AU - Corber, A. T2 - International Journal of Aerospace Engineering SN - 1687-5966 SP - 217463 KW - Critical component KW - Engine operating conditions KW - Gas turbine combustor KW - Multi-disciplinary collaborations KW - Numerical results KW - Reacting flow field KW - Systematic study KW - Working environment KW - Engines KW - Fatigue of materials KW - Fleet operations KW - Flow fields KW - Gas turbines KW - Thermodynamics KW - Combustors AB - In order to assess the remaining life of gas turbine critical components, it is vital to accurately define the aerothermodynamic working environments and service histories. As a part of a major multidisciplinary collaboration program, a benchmark modeling on a practical gas turbine combustor is successfully carried out, and the two-phase, steady, turbulent, compressible, reacting flow fields at both cruise and takeoff are obtained. The results show the complicated flow features inside the combustor. The airflow over each flow element of the combustor can or liner is not evenly distributed, and considerable variations, ±25, around the average values, are observed. It is more important to note that the temperatures at the combustor can and cooling wiggle strips vary significantly, which can significantly affect fatigue life of engine critical components. The present study suggests that to develop an adequate aerothermodynamics tool, it is necessary to carry out a further systematic study, including validation of numerical results, simulations at typical engine operating conditions, and development of simple correlations between engine operating conditions and component working environments. As an ultimate goal, the cost and time of gas turbine engine fleet management must be significantly reduced. © 2012 Leiyong Jiang and Andrew Corber. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b0b45691-93e0-4b9d-862a-736ce0f02332 ER - TY - JOUR TI - Semiautomated panning of naive camelidae libraries and selection of single-domain antibodies against peptide antigens DO - 10.1007/978-1-61779-968-6-7 AU - Kumaran, J. AU - MacKenzie, C.R. AU - Arbabi-Ghahroudi, M. T2 - Methods in Molecular Biology SN - 1064-3745 SN - 9781617799679 VL - 911 SP - 105 EP - 124 KW - antigen KW - nanobody KW - peptide antigen KW - unclassified drug KW - peptide KW - antibody library KW - antigen binding KW - antigen expression KW - antigen purification KW - article KW - Artiodactyla KW - biopanning KW - Camelidae KW - controlled study KW - epitope mapping KW - nonhuman KW - phage display KW - priority journal KW - protein protein interaction KW - screening test KW - semiautomated panning method KW - animal KW - antibody affinity KW - Artiodactyla KW - cell surface display KW - chemistry KW - genetics KW - immunology KW - isolation and purification KW - laboratory automation KW - methodology KW - peptide library KW - Animals KW - Antibody Affinity KW - Antigens KW - Automation, Laboratory KW - Camelids, New World KW - Cell Surface Display Techniques KW - Peptide Library KW - Peptides KW - Single-Domain Antibodies AB - With the identification of vast numbers of novel proteins through genomic and proteomic initiatives, the need for efficient processes to characterize and target them has increased. Antibodies are naturally designed molecules that can fulfill this need, and in vitro methodologies for isolating them from either immune or naïve sources have been extensively developed. However, access to pure protein antigens for screening purposes is a major hurdle due to the limitations associated with recombinant production of eukaryotic proteins. Consequently, rational peptide design based on proteomic methodologies such as protein modeling, secondary sequence prediction, and hydrophobicity/ hydrophilicity prediction, in combination with other bioinformatics data, is being explored as a viable solution to isolate specific antibodies against difficult antigens. Single-domain antibodies are becoming the ideal antibody format due to their structural advantages and ease of production compared to conventional antibodies and antibody fragments derived from conventional antibodies. For screening purposes, phage display technology is a well-established technique. With this technique, a repertoire of antibody fragments can be displayed on the surface of filamentous phages (f1, fd, M13) followed by screening against various antigenic targets. Furthermore, the technique can be expanded to a high-throughput scale using a magnetic-based, in-solution panning protocol which allows for the screening of multiple target antigens simultaneously. In this chapter, we describe a semiautomated panning method to screen a naïve Camelidae library against rationally designed peptide antigens, followed by preliminary characterization of isolated binders. © 2012 Springer Science+Business Media, LLC. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cc8da3e7-13b1-4937-acb9-68ca729145d9 ER - TY - JOUR TI - VLBI for Gravity Probe B. I. overview DO - 10.1088/0067-0049/201/1/1 AU - Shapiro, I.I. AU - Bartel, N. AU - Bietenholz, M.F. AU - Lebach, D.E. AU - Lestrade, J.-F. AU - Ransom, R.R. AU - Ratner, M.I. T2 - Astrophysical Journal, Supplement Series SN - 0067-0049 VL - 201 IS - 1 SP - 1 AB - We describe the NASA/Stanford gyroscope relativity mission, Gravity Probe B (GP-B), and provide an overview of the following series of six astrometric and astrophysical papers that report on our radio observations and analyses made in support of this mission. The main goal of this 8.5year program of differential very long baseline interferometry astrometry was to determine the proper motion of the guide star of the GP-B mission, the RS CVn binary IM Pegasi (IM Peg; HR 8703). This proper motion is determined with respect to compact, extragalactic reference sources. The results are -20.833 ± 0.090masyr -1 and -27.267 ± 0.095masyr -1 for, respectively, the right ascension and declination, in local Cartesian coordinates, of IM Peg's proper motion, and 10.370 ± 0.074mas (i.e., 96.43 ± 0.69pc) for its parallax (and distance). Each quoted uncertainty is meant to represent an 70% confidence interval that includes the estimated contribution from systematic error. These results are accurate enough not to discernibly degrade the GP-B estimates of its gyroscopes' relativistic precessions: the frame-dragging and geodetic effects. © 2012. The American Astronomical Society. All rights reserved.. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : efea4a6f-e0c7-4dbb-b66f-b7bd031a759b ER - TY - JOUR TI - SN-38 loaded polymeric micelles to enhance cancer therapy DO - 10.1088/0957-4484/23/20/205101 AU - Gu, Q. AU - Xing, J.Z. AU - Huang, M. AU - He, C. AU - Chen, J. T2 - Nanotechnology SN - 0957-4484 VL - 23 IS - 20 SP - 205101 KW - Aqueous suspensions KW - Cancer cells KW - Cancer therapy KW - Caprolactone KW - Drug loading KW - Drug release KW - Encapsulation efficiency KW - Fetal bovine serum KW - Hydration method KW - In-vitro KW - Inhibitory concentration KW - Low toxicity KW - Lung cells KW - Modified film KW - Phosphate-buffered salines KW - Pluronics KW - Polymeric micelle KW - Propylene glycols KW - Transmission electron microscopy (TEM) KW - Atomic force microscopy KW - Dynamic light scattering KW - Encapsulation KW - Loading KW - Nanoparticles KW - Transmission electron microscopy KW - Polyethylene glycols KW - antineoplastic agent KW - camptothecin KW - drug derivative KW - irinotecan KW - nanocapsule KW - apoptosis KW - article KW - cell survival KW - chemistry KW - diffusion KW - drug effect KW - experimental neoplasm KW - human KW - metabolism KW - micelle KW - tumor cell culture KW - Antineoplastic Agents, Phytogenic KW - Apoptosis KW - Camptothecin KW - Cell Survival KW - Diffusion KW - Humans KW - Micelles KW - Nanocapsules KW - Neoplasms, Experimental KW - Tumor Cells, Cultured AB - 7-Ethyl-10-hydroxycamptothecin (SN-38) loaded poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (Pluronic F-108) and poly(ethylene glycol)-block-poly("-caprolactone) (PEG-b-PCL) nanoparticles were successfully prepared by a modified film hydration method and characterized by scanning electric microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and dynamic light scattering (DLS). Satisfactory drug loading of 20.73 ± 0.66% and a high encapsulation efficiency of 83:83 ± 1:32% were achieved. The SN-38 nanoparticles (SN-38 NPs) can completely disperse into a phosphate buffered saline (PBS) medium to produce a clear aqueous suspension that remains stable for up to three days. Total drug releases were 67.91% and 91.09% after 24 h in a PBS or fetal bovine serum (FBS) medium. Half maximal inhibitory concentration (IC50) tests of SN-38 and SN-38 NPs on A549 lung cells produced results of 200.0±14.9 ng ml -1 and 80.0±4.6 ng ml -1, respectively. Similarly, IC50 tests of SN-38 and SN-38 NPs on MCF-7 breast cells yielded results of 16.0 ± 0.7 ng ml -1 and 8.0 ± 0.5 ng ml -1, respectively. These in vitro IC 50 studies show significant (p < 0.01) enhancement of the SN-38 NP drug efficiency in killing cancer cells in comparison to the free drug SN-38 control. All the materials used for this nanoformulation are approved by the US FDA, with the virtue of extremely low toxicity to normal cells. © 2012 IOP Publishing Ltd. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7a32c2f4-ed33-4747-b065-75df8c14a016 ER - TY - JOUR TI - Testing large flats with computer generated holograms DO - 10.1117/12.927064 AU - Pariani, G. AU - Tresoldi, D. AU - Spanò, P. AU - Bianco, A. T2 - Modern Technologies in Space- and Ground-Based Telescopes and Instrumentation II T2 - SPIE - International Society for Optical Engineering. Proceedings; 8450 T3 - Modern Technologies in Space- and Ground-Based Telescopes and Instrumentation II, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491510 SP - 84500Z KW - CGH KW - Collimated light KW - Computer generated holograms KW - Fabrication errors KW - Flat mirrors KW - Optical test KW - Spherical mirror KW - Test KW - Wavefront correction KW - Alignment KW - Computer generated holography KW - Holograms KW - Interferometers KW - Mirrors KW - Optical telescopes KW - Spheres KW - Telescopes KW - Optical testing AB - We describe the optical test of a large flat based on a spherical mirror and a dedicated CGH. The spherical mirror, which can be accurately manufactured and tested in absolute way, allows to obtain a quasi collimated light beam, and the hologram performs the residual wavefront correction. Alignment tools for the spherical mirror and the hologram itself are encoded in the CGH. Sensitivity to fabrication errors and alignment has been evaluated. Tests to verify the effectiveness of our approach are now under execution. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a0e346bd-0610-4802-af3b-6b399940b0ec ER - TY - JOUR TI - A multi-point ultrasonic detection approach to fretting crack detection in an aircraft component DO - 10.1117/12.915382 AU - Wu, K.-T. AU - Sun, Z. AU - Jen, C.-K. AU - Blouin, A. AU - Mrad, N. AU - Bélanger, H. T2 - Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2012 T2 - SPIE - International Society for Optical Engineering. Proceedings; 8347 T3 - Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2012, 12 March 2012 through 15 March 2012, San Diego, CA SN - 0277-786X SN - 9780819490049 SP - 834710 KW - Aircraft components KW - Aircraft stabilizers KW - Detection approach KW - Performance requirements KW - Rivet hole KW - Sensor output KW - Shear horizontal waves KW - Surface shear KW - Ultrasonic detection KW - Acoustics KW - Aerospace engineering KW - Crack detection KW - Nondestructive examination KW - Optical engineering KW - Shear flow KW - Ultrasonic testing KW - Fretting corrosion AB - A naturally cracked aircraft stabilizer former has been examined. By using surface shear horizontal diagnostic acoustic waves and a multi-point detection approach, a fretting crack, 0.2-inch long, 0.03-inch deep and at 0.06-inch to a rivet hole has been clearly identified. The proposed approach provides a simple way to interpret sensor output without imposing demanding transducer performance requirements. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a48e93fd-4580-4785-bb40-8db974cb6a6f ER - TY - JOUR TI - SPIRou @ CFHT: Data reduction software and simulation tools DO - 10.1117/12.926334 AU - Artigau, É. AU - Bouchy, F. AU - Delfosse, X. AU - Bonfils, X. AU - Donati, J.-F. AU - Figueira, P. AU - Thanjavur, K. AU - Lafrenière, D. AU - Doyon, R. AU - Surace, C. AU - Moutou, C. AU - Boisse, I. AU - Saddlemyer, L. AU - Loop, D. AU - Kouach, D. AU - Pepe, F. AU - Lovis, C. AU - Hernandez, O. AU - Wang, S.-Y. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Software and Cyberinfrastructure for Astronomy II, 1 July 2012 through 4 July 2012, Amsterdam SN - 0277-786X SN - 9780819491527 VL - 8451 SP - 84513I KW - Absorption lines KW - Data simulation KW - Echelle KW - Exo-planets KW - High-precision KW - Instrumentation KW - Near Infrared KW - Near-infrared domains KW - Reduction software KW - Spectropolarimeters KW - Spectropolarimetry KW - Technical design KW - Thermal background KW - Astronomy KW - Data processing KW - Data reduction KW - Infrared devices KW - Instruments KW - Polarimeters KW - Spectroscopy KW - Tools AB - SPIRou is a near-infrared, echelle spectropolarimeter/velocimeter under design for the 3.6m Canada-France-Hawaii Telescope (CFHT) on Mauna Kea, Hawaii. The unique scientific capabilities and technical design features are described in the accompanying papers at this conference. In this paper we focus on the data reduction software (DRS) and the data simulation tool. The SPIRou DRS builds upon the experience of the existing SOPHIE, HARPS and ESPADONS spectrographs; class-leaders instruments for high-precision RV measurements and spectropolarimetry. While SPIRou shares many characteristics with these instruments, moving to the near-infrared domain brings specific data-processing challenges: the presence of a large number of telluric absorption lines, strong emission sky lines, thermal background, science arrays with poorer cosmetics, etc. In order for the DRS to be fully functional for SPIRou's first light in 2015, we developed a data simulation tool that incorporates numerous instrumental and observational effects. We present an overview of the DRS and the simulation tool architectures. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 87b9b560-b30f-4d5b-b0f6-2ba86337aebd ER - TY - JOUR TI - Monitoring the switch: The warburg effect and targeted proteomic analysis of cancer metabolism AU - Murphy, J.P. AU - Côté, P.D. AU - Pinto, D.M. T2 - Current Proteomics SN - 1570-1646 VL - 9 IS - 1 SP - 26 EP - 39 KW - glucose KW - glucose 6 phosphate dehydrogenase KW - hexokinase KW - hexokinase 2 KW - hypoxia inducible factor 1 KW - immunoglobulin enhancer binding protein KW - mammalian target of rapamycin KW - Myc protein KW - phosphatidylinositol 3 kinase KW - phosphatidylinositol 3,4,5 trisphosphate 3 phosphatase KW - protein kinase B KW - protein p53 KW - pyruvate kinase KW - pyruvate kinase M2 KW - reduced nicotinamide adenine dinucleotide phosphate KW - unclassified drug KW - alternative RNA splicing KW - apoptosis KW - article KW - cancer metabolism KW - cancer prognosis KW - cell metabolism KW - cell proliferation KW - computer model KW - computer prediction KW - fatty acid synthesis KW - functional proteomics KW - gene expression regulation KW - gene overexpression KW - gene targeting KW - glucose transport KW - glycolysis KW - human KW - liquid chromatography KW - liquid chromatography multiple reaction monitoring KW - malignant neoplastic disease KW - metabolic rate KW - metabolism KW - monitoring KW - nonhuman KW - nucleic acid synthesis KW - priority journal KW - protein protein interaction KW - tumor microenvironment KW - Warburg effect AB - Cancer cells dramatically alter their metabolism in order to increase the production rate of intermediates required for nucleic and fatty acid biosynthesis in rapidly proliferating cells. While not well understood, dysregulation of oncogenes and tumour suppressors appears to result in the altered expression of specific isoforms of glycolysis proteins. A full understanding of glycolytic alterations in cancer through a systems biology approach requires tools to observe changes in the set of proteins that make up the glycolytic proteome. We propose that a targeted proteomics approach employing multiple reaction monitoring (MRM) is an excellent strategy to quantitatively monitor sets of proteins, such as those making up the glycolytic proteome. MRM is particularly well suited to proteins of glycolysis as they are of moderate to high abundance. Such systems-based efforts provide a means to understand the mechanisms for an altered glycolytic proteome in cancer, perhaps leading to novel drug targets and metabolic signatures for use in cancer prognosis. ©2012 Bentham Science Publishers. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 79abda0d-af9d-4dd8-a3e4-6e9d0802908f ER - TY - JOUR TI - Metal mesh heating element size effect in resistance welding of thermoplastic composites DO - 10.1177/0021998311412986 AU - Dubé, M. AU - Hubert, P. AU - Gallet, J.N.A.H. AU - Stavrov, D. AU - Bersee, H.E.N. AU - Yousefpour, A. T2 - Journal of Composite Materials SN - 0021-9983 VL - 46 IS - 8 SP - 911 EP - 919 KW - Joints/joining KW - Lap shear KW - Lap shear strength KW - Metal mesh KW - Size effects KW - Thermoplastic composite KW - Wire diameter KW - Composite materials KW - Ethers KW - Ketones KW - Organic compounds KW - Polymer matrix composites KW - Resistance welding KW - Thermoplastics KW - Welding KW - Electric heating elements KW - Composites KW - Electric Heating KW - Ethers KW - Joining KW - Joints KW - Ketones KW - Thermoplastics KW - Welding AB - The objective of this work is to determine the effects of metal mesh heating element size on resistance welding of thermoplastic composites. The materials to be resistance-welded consisted of carbon fiber/poly-ether-ketone- ketone (CF/PEKK), carbon fiber/poly-ether-imide (CF/PEI) and glass fiber/PEI (GF/PEI). Four different metal mesh sizes were used as heating elements. The samples were welded in a lap shear joint configuration and mechanically tested. Maximum Lap Shear Strengths of 52, 47 and 33 MPa were obtained for the CF/PEKK, CF/PEI and GF/PEI specimens, respectively. The ratio of the heating element's fraction of open area and wire diameter was shown to be the most important parameter to be considered when selecting an appropriate heating element size. © The Author(s) 2011. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8a6c5154-b798-46e2-8ad9-7c233761c7f8 ER - TY - JOUR TI - Impact of initial surface parameters on the final quality of laser micro-polished surfaces DO - 10.1117/12.908137 AU - Chow, M. AU - Bordatchev, E.V. AU - Knopf, G.K. T2 - Progress in Biomedical Optics and Imaging - Proceedings of SPIE T3 - Micromachining and Microfabrication Process Technology XVII, 24 January 2012 through 26 January 2012, San Francisco, CA SN - 1605-7422 SN - 9780819488916 VL - 8248 SP - 824809 KW - Experimental analysis KW - Finishing operation KW - H13 tool steel KW - Initial surface microgeometry KW - Laser-material interactions KW - Local minimums KW - Low power laser KW - Machined surface KW - Micro milling KW - Micro-fabrication technology KW - Polishing effects KW - Process parameters KW - Q switched Nd:YAG laser KW - Surface parameter KW - Thin layers KW - Top surface KW - Waviness KW - Composite micromechanics KW - Microanalysis KW - Microfabrication KW - Micromachining KW - Molten materials KW - Polishing KW - Surface roughness KW - Surface tension KW - Tool steel KW - Surfaces AB - Laser micro-polishing (LμP) is a new laser-based microfabrication technology for improving surface quality during a finishing operation and for producing parts and surfaces with near-optical surface quality. The LμP process uses low power laser energy to melt a thin layer of material on the previously machined surface. The polishing effect is achieved as the molten material in the laser-material interaction zone flows from the elevated regions to the local minimum due to surface tension. This flow of molten material then forms a thin ultra-smooth layer on the top surface. The LμP is a complex thermo-dynamic process where the melting, flow and redistribution of molten material is significantly influenced by a variety of process parameters related to the laser, the travel motions and the material. The goal of this study is to analyze the impact of initial surface parameters on the final surface quality. Ball-end micromilling was used for preparing initial surface of samples from H13 tool steel that were polished using a Q-switched Nd:YAG laser. The height and width of micromilled scallops (waviness) were identified as dominant parameter affecting the quality of the LμPed surface. By adjusting process parameters, the Ra value of a surface, having a waviness period of 33 μm and a peak-to-valley value of 5.9 μm, was reduced from 499 nm to 301 nm, improving the final surface quality by 39.7%. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 882c87a4-6c7b-4018-9f0d-0cb9505a0247 ER - TY - JOUR TI - Solubility and stability engineering of human VH domains DO - 10.1007/978-1-61779-968-6-21 AU - Kim, D.Y. AU - Ding, W. AU - Tanha, J. T2 - Methods in Molecular Biology SN - 1064-3745 SN - 9781617799679 VL - 911 SP - 355 EP - 372 KW - antibody KW - unclassified drug KW - vh antibody KW - disulfide KW - nanobody KW - article KW - priority journal KW - protein engineering KW - protein stability KW - solubility KW - amino acid sequence KW - chemistry KW - complementarity determining region KW - gene expression KW - genetics KW - human KW - isolation and purification KW - molecular cloning KW - molecular genetics KW - mutation KW - plasmid KW - protein engineering KW - temperature KW - Amino Acid Sequence KW - Cloning, Molecular KW - Complementarity Determining Regions KW - Disulfides KW - Gene Expression KW - Humans KW - Molecular Sequence Data KW - Mutation KW - Plasmids KW - Protein Engineering KW - Protein Stability KW - Single-Domain Antibodies KW - Solubility KW - Temperature AB - Solubility and stability are amongst the factors contributing to the therapeutic efficacy of biologics. Human antibody heavy chain variable domains, VHs, are one class of biologics; improving VH biophysical properties is the focus of significant protein engineering efforts. Here, we describe an efficacy engineering approach which involves the introduction of a disulfide linkage in the VH core and which improves both VH solubility and stability. More specifically, we describe protocols for generation of disulfide engineered human VHs and their characterization in terms of disulfide linkage formation, non-aggregation, and stability. Our solubility/stability engineering approach may be applied to other VHs. © 2012 Springer Science+Business Media, LLC. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 60c55c9c-7090-43c2-a0d6-ce2d3279073d ER - TY - JOUR TI - On liquation and liquid phase oxidation during linear friction welding of nickel-base in 738 and CMSX 486 superalloys AU - Amegadzie, M.Y. AU - Ola, O.T. AU - Ojo, O.A. AU - Wanjara, P. AU - Chaturvedi, M.C. T2 - Proceedings of the International Symposium on Superalloys T3 - 12th International Symposium on Superalloys, Superalloys 2012, 9 September 2012 through 13 September 2012, Seven Springs, PA SN - 9780470943205 SP - 587 EP - 594 KW - Atmospheric oxygen KW - Conventionally casts KW - Linear friction welding KW - Liquation KW - Liquid-phase oxidation KW - Micro-structural KW - Nickel base superalloy KW - Thermomechanical simulation KW - Compressive stress KW - Friction welding KW - Liquids KW - Mechanical properties KW - Nickel KW - Oxidation KW - Oxide films KW - Thermomechanical treatment KW - Welds KW - Superalloys AB - A systematic study of the microstructural response of conventionally cast IN 738 and single crystal CMSX 486 superalloys during linear friction welding was performed. The results revealed that, aside from a significant liquation of various phases that occurred during joining, continuous oxide films formed on the weld lines in both materials. The weld line oxides consisted of aluminum-rich and hafnium-base oxides in IN 738 and CMSX 486 superalloys, respectively, which can be deleterious to the mechanical properties of the weld joint. Gleeble thermo-mechanical simulation showed that the oxides were produced by the oxidation of some liquid exposed to atmospheric oxygen at the mating surfaces of the work pieces. A practicable method of eliminating liquid phase oxidation during linear friction welding of nickel-base superalloys is discussed. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 10165179-3f44-4f18-89bd-869b37fadd4f ER - TY - JOUR TI - A novel method to prepare pet nanocomposites by water-assisted melt compounding AU - Dini, M. AU - Carreau, P.J. AU - Mousavand, T. AU - Kamal, M.R. AU - Ton-That, M.-T. T2 - Annual Technical Conference - ANTEC, Conference Proceedings T3 - 70th Annual Technical Conference of the Society of Plastics Engineers 2012, ANTEC 2012, 2 April 2012 through 4 April 2012, Orlando, FL SN - 9781622760831 VL - 1 SP - 563 EP - 568 KW - Cloisite KW - Feed-rates KW - Melt-compounding KW - Rheometry KW - Twin screw extruders KW - Wide angle Xray diffraction KW - Differential scanning calorimetry KW - Plastic products KW - Polyethylene terephthalates KW - Scanning electron microscopy KW - Sodium KW - X ray diffraction KW - Nanocomposites AB - Polyethylene terephthalate (PET) nanocomposites were prepared via melt compounding of PET using a twin screw extruder. Water was fed to the extruder to assist in intercalation/exfoliation. The ratio between the water and PET feed rates was varied and Cloisite Na +, Cloisite 30B and Nanomer I.238E were used. Wide angle x-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and rheometry were used to characterize the PET nanocomposites. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 25075a91-401c-4f6d-b4e7-9f3e753db373 ER - TY - JOUR TI - Herzberg Institute of Astrophysics' vibration measurement capabilities with applications to astronomical instrumentation DO - 10.1117/12.928861 AU - Byrnes, P. W. G. T2 - Ground-Based and Airborne Telescopes IV T2 - SPIE - International Society for Optical Engineering. Proceedings; 8444 T3 - Ground-Based and Airborne Telescopes IV, July 1-6, 2012, Amsterdam, The Netherlands SN - 0277-786X SN - 9780819491459 SP - 84443D KW - Astronomical instrumentation KW - Electrodynamic exciters KW - Future applications KW - Impulse hammers KW - LabVIEW virtual instrument KW - Modal test KW - Piezo-electric accelerometers KW - Structural response KW - Technology research KW - Vibration test KW - Airborne telescopes KW - Instruments KW - Modal analysis KW - Vibration measurement KW - Astrophysics AB - The Herzberg Institute of Astrophysics, Astronomy Technology Research Group's vibration measurement capabilities include modal test via impulse hammer or electrodynamic exciter, structural response monitoring via piezoelectric accelerometers, and data acquisition via LabVIEW virtual instruments. This paper will review our existing capabilities, and give examples of past and future applications relevant to astronomical instrumentation. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e0e4a422-1e35-4bdc-b4c9-f4e7062c80a2 ER - TY - JOUR TI - Functional control of the Candida albicans cell wall by catalytic protein kinase A subunit Tpk1 DO - 10.1111/j.1365-2958.2012.08193.x AU - Fanning, S. AU - Xu, W. AU - Beaurepaire, C. AU - Suhan, J.P. AU - Nantel, A. AU - Mitchell, A.P. T2 - Molecular Microbiology SN - 0950-382X VL - 86 IS - 2 SP - 284 EP - 302 KW - caspofungin KW - cell protein KW - cell surface protein KW - cyclic AMP dependent protein kinase catalytic subunit KW - protein Als1 KW - protein Als2 KW - protein Als4 KW - protein Csh1 KW - protein Csp37 KW - protein Tpk1 KW - unclassified drug KW - antibiotic sensitivity KW - article KW - bacterial cell wall KW - bacterium adherence KW - biofilm KW - Candida albicans KW - cell adhesion KW - cell wall KW - controlled study KW - gene expression KW - gene function KW - gene identification KW - gene repression KW - genetic epistasis KW - genetic regulation KW - homozygosity KW - nonhuman KW - nucleotide sequence KW - priority journal KW - repressor gene KW - Tpk1 gene KW - transcription regulation KW - Biofilms KW - Candida albicans KW - Cell Wall KW - Cyclic AMP-Dependent Protein Kinase Catalytic Subunits KW - Fungal Proteins KW - Gene Expression Regulation, Fungal KW - Candida albicans AB - The cyclic AMP protein kinase A pathway governs numerous biological features of the fungal pathogen Candida albicans. The catalytic protein kinase A subunits, Tpk1 (orf19.4892) and Tpk2 (orf19.2277), have divergent roles, and most studies indicate a more pronounced role for Tpk2. Here we dissect two Tpk1-responsive properties: adherence and cell wall integrity. Homozygous tpk1/tpk1 mutants are hyperadherent, and a Tpk1 defect enables biofilm formation in the absence of Bcr1, a transcriptional regulator of biofilm adhesins. A quantitative gene expression-based assay reveals that tpk1/tpk1 and bcr1/bcr1 genotypes show mixed epistasis, as expected if Tpk1 and Bcr1 act mainly in distinct pathways. Overexpression of individual Tpk1-repressed genes indicates that cell surface proteins Als1, Als2, Als4, Csh1 and Csp37 contribute to Tpk1-regulated adherence. Tpk1 is also required for cell wall integrity, but has no role in the gene expression response to cell wall inhibition by caspofungin. Interestingly, increased expression of the adhesin gene ALS2 confers a cell wall defect, as manifested in hypersensitivity to the cell wall inhibitor caspofungin and a shallow cell wall structure. Our findings indicate that Tpk1 governs C.albicans cell wall properties through repression of select cell surface protein genes. © 2012 Blackwell Publishing Ltd. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4f631e31-c6f2-4352-914e-b1a2949e42d4 ER - TY - JOUR TI - Extrusion foaming behavior of pet AU - Barzegari, M.R. AU - Hossieny, N. AU - Keshkar, M. AU - Chapleau, N. AU - Park, C.B. T2 - Annual Technical Conference - ANTEC, Conference Proceedings T3 - 70th Annual Technical Conference of the Society of Plastics Engineers 2012, ANTEC 2012, 2 April 2012 through 4 April 2012, Orlando, FL SN - 9781622760831 VL - 3 SP - 2389 EP - 2393 KW - Cell structure KW - Chain extenders KW - Degree of crystallinity KW - Die temperatures KW - Expansion ratio KW - Extrudates KW - Extrusion foaming KW - Carbon dioxide KW - Differential scanning calorimetry KW - Nanocomposites KW - Plastic products KW - Polyethylene terephthalates KW - Scanning electron microscopy KW - Foams AB - The extrusion foaming behavior of polyethylene terephthalate (PET) with CO 2 was evaluated. The foaming morphologies of PET/nanocomposites and PET/chain extenders were also assessed. The foamed extrudates were analyzed for expansion ratio, cell structure, and degree of crystallinity using scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Finally, the effect of the die temperature on the cell structure of the PET foam samples was studied. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d0fb38f0-1e0f-4c2a-8440-2c3b7e54df3e ER - TY - JOUR TI - Blunted epidermal L-tryptophan metabolism in vitiligo affects immune response and ROS scavenging by Fenton chemistry, Part 2: Epidermal H 2O2/ONOO--mediated stress in vitiligo hampers indoleamine 2,3-dioxygenase and aryl hydrocarbon receptor-mediated immune response signaling DO - 10.1096/fj.11-201897 AU - Schallreuter, K.U. AU - Salem, M.A.E.L. AU - Gibbons, N.C.J. AU - Maitland, D.J. AU - Marsch, E. AU - Elwary, S.M.A. AU - Healey, A.R. T2 - FASEB Journal SN - 0892-6638 VL - 26 IS - 6 SP - 2471 EP - 2485 KW - aromatic hydrocarbon receptor KW - cyclooxygenase 2 KW - cytochrome P450 1A1 KW - hydrogen peroxide KW - indoleamine 2,3 dioxygenase KW - peroxynitrite KW - reactive oxygen metabolite KW - tryptophan KW - tryptophan hydroxylase KW - adult KW - article KW - clinical article KW - controlled study KW - Fenton reaction KW - Fourier transform mass spectrometry KW - human KW - immune response KW - in vitro study KW - in vivo study KW - mass spectrometry KW - priority journal KW - Raman spectrometry KW - regulatory T lymphocyte KW - stress KW - vitiligo KW - Computer Simulation KW - Epidermis KW - Humans KW - Hydrogen Peroxide KW - Indoleamine-Pyrrole 2,3,-Dioxygenase KW - Oxidative Stress KW - Peroxynitrous Acid KW - Receptors, Aryl Hydrocarbon KW - Signal Transduction KW - T-Lymphocytes, Regulatory KW - Tryptophan KW - Vitiligo AB - Vitiligo is characterized by a mostly progressive loss of the inherited skin color. The cause of the disease is still unknown, despite accumulating in vivo and in vitro evidence of massive oxidative stress via hydrogen peroxide (H2O2) and peroxynitrite (ONOO-) in the skin of affected individuals. The most favored hypothesis is based on autoimmune mechanisms. Since depletion of the essential amino acid L-tryptophan (Trp) severely affects various immune responses, we here looked at Trp metabolism and signaling in these patients. Our in vivo and in vitro data revealed total absence of epidermal Trp hydroxylase activities and the presence of H 2O2/ONOO- deactivated indoleamine 2,3-dioxygenase. Aryl hydrocarbon receptor signaling is severely impaired despite the ligand (Trp dimer) being formed, as shown by mass spectrometry. Loss of this signal is supported by the absence of downstream signals (COX-2 and CYP1A1) as well as regulatory T-lymphocytes and by computer modeling. In vivo Fourier transform Raman spectroscopy confirmed the presence of Trp metabolites together with H2O2 supporting deprivation of the epidermal Trp pool by Fenton chemistry. Taken together, our data support a long-expressed role for in loco redox balance and a distinct immune response. These insights could open novel treatment strategies for this disease. © FASEB. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e5ac2ae4-360f-4662-856f-5520fbd07ea0 ER - TY - JOUR TI - Unfolding linac photon spectra and incident electron energies from experimental transmission data, with direct independent validation DO - 10.1118/1.4754301 AU - Ali, E.S.M. AU - McEwen, M.R. AU - Rogers, D.W.O. T2 - Medical Physics SN - 0094-2405 VL - 39 IS - 11 SP - 6585 EP - 6596 KW - article KW - electron KW - human KW - methodology KW - Monte Carlo method KW - photon KW - reproducibility KW - spectroscopy KW - statistics KW - Electrons KW - Humans KW - Monte Carlo Method KW - Photons KW - Reproducibility of Results KW - Spectrum Analysis KW - Statistics as Topic AB - Purpose: In a recent computational study, an improved physics-based approach was proposed for unfolding linac photon spectra and incident electron energies from transmission data. In this approach, energy differentiation is improved by simultaneously using transmission data for multiple attenuators and detectors, and the unfolding robustness is improved by using a four-parameter functional form to describe the photon spectrum. The purpose of the current study is to validate this approach experimentally, and to demonstrate its application on a typical clinical linac. Methods: The validation makes use of the recent transmission measurements performed on the Vickers research linac of National Research Council Canada. For this linac, the photon spectra were previously measured using a NaI detector, and the incident electron parameters are independently known. The transmission data are for eight beams in the range 10-30 MV using thick Be, Al and Pb bremsstrahlung targets. To demonstrate the approach on a typical clinical linac, new measurements are performed on an Elekta Precise linac for 6, 10 and 25 MV beams. The different experimental setups are modeled using EGSnrc, with the newly added photonuclear attenuation included. Results: For the validation on the research linac, the 95 confidence bounds of the unfolded spectra fall within the noise of the NaI data. The unfolded spectra agree with the EGSnrc spectra (calculated using independently known electron parameters) with RMS energy fluence deviations of 4.5. The accuracy of unfolding the incident electron energy is shown to be ∼3. A transmission cutoff of only 10 is suitable for accurate unfolding, provided that the other components of the proposed approach are implemented. For the demonstration on a clinical linac, the unfolded incident electron energies and their 68 confidence bounds for the 6, 10 and 25 MV beams are 6.1 ± 0.1, 9.3 ± 0.1, and 19.3 ± 0.2 MeV, respectively. The unfolded spectra for the clinical linac agree with the EGSnrc spectra (calculated using the unfolded electron energies) with RMS energy fluence deviations of 3.7. The corresponding measured and EGSnrc-calculated transmission data agree within 1.5, where the typical transmission measurement uncertainty on the clinical linac is 0.4 (not including the uncertainties on the incident electron parameters). Conclusions: The approach proposed in an earlier study for unfolding photon spectra and incident electron energies from transmission data is accurate and practical for clinical use. © 2012 American Association of Physicists in Medicine. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f17b9404-7208-44c3-bea2-86ec955eb1d5 ER - TY - JOUR TI - Evaluation of brain tumor vessels specific contrast agents for glioblastoma imaging DO - 10.1093/neuonc/nor183 AU - Tomanek, B. AU - Iqbal, U. AU - Blasiak, B. AU - Abulrob, A. AU - Albaghdadi, H. AU - Matyas, J.R. AU - Ponjevic, D. AU - Sutherland, G.R. T2 - Neuro-Oncology SN - 1522-8517 VL - 14 IS - 1 SP - 53 EP - 63 KW - binding protein KW - contrast medium KW - dextran KW - growth factor KW - nuclear magnetic resonance imaging agent KW - superparamagnetic iron oxide KW - vascular targeting agent KW - animal experiment KW - animal model KW - animal tissue KW - article KW - brain blood vessel KW - brain tumor KW - cancer tissue KW - controlled study KW - fluorescence microscopy KW - glioblastoma KW - in vivo study KW - infrared radiation KW - inoculation KW - male KW - mouse KW - near infrared spectroscopy KW - nonhuman KW - nuclear magnetic resonance imaging KW - relaxation time KW - Animals KW - Antibodies KW - Brain Neoplasms KW - Cell Line, Tumor KW - Contrast Media KW - Dextrans KW - Ferric Compounds KW - Glioblastoma KW - Humans KW - Insulin-Like Growth Factor Binding Proteins KW - Magnetic Resonance Imaging KW - Male KW - Mice KW - Mice, Nude KW - Microscopy, Fluorescence KW - Nanoparticles AB - A mouse model of glioblastoma multiforme was used to determine the accumulation of a targeted contrast agent in tumor vessels. The contrast agent, consisting of superparamagnetic iron oxide coated with dextran, was functionalized with an anti-insulin-like-growth-factor binding protein 7 (anti-IGFBP7) single domain antibody. The near infrared marker, Cy5.5, was also attached for an in vivo fluorescence study. A 9.4T magnetic resonance imaging (MRI) system was used for in vivo studies on days 10 and 11 following tumor inoculation. T2 relaxation time was used to measure the accumulation of the contrast agent in the tumor. Changes in tumor to brain contrast because of active targeting were compared with a nontargeted contrast agent. Effective targeting was confirmed with near infrared measurements and fluorescent microscopic analysis. The results showed that there was a statistically significant (P < .01) difference in normalized T2 between healthy brain and tumor tissue 10 min, 1 h, and 2 h point postinjection of the anti-IGFBP7 single domain antibody targeted and nontargeted iron oxide nanoparticles. A statistical difference remained in animals treated with targeted nanoparticles 24 h postinjection only. The MRI, near infrared imaging, and fluorescent microscopy studies showed corresponding spatial and temporal changes. We concluded that the developed anti-IGFBP7-iron oxide single domain antibodytargeted MRI contrast agent selectively binds to abnormal vessels within a glioblastoma. T2-weighted MRI and near infrared imaging are able to detect the targeting effects in brain tumors. © The Author(s) 2011. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e53e0f53-9eaf-4f78-8e84-5b7a98eff04d ER - TY - JOUR TI - In Vitro and in Vivo biological activities of iron chelators and gallium nitrate against Acinetobacter baumannii DO - 10.1128/AAC.00778-12 AU - De Léséleuc, L. AU - Harris, G. AU - KuoLee, R. AU - Chen, W. T2 - Antimicrobial Agents and Chemotherapy SN - 0066-4804 VL - 56 IS - 10 SP - 5397 EP - 5400 KW - 2,2' bipyridine KW - chelating agent KW - gallium nitrate KW - transferrin KW - Acinetobacter baumannii KW - animal experiment KW - article KW - bacterial growth KW - bacterial load KW - bacteriostasis KW - controlled study KW - growth inhibition KW - in vitro study KW - in vivo study KW - iron metabolism KW - iron restriction KW - mouse KW - nonhuman KW - priority journal KW - 2,2'-Dipyridyl KW - Acinetobacter baumannii KW - Acinetobacter Infections KW - Animals KW - Gallium KW - Iron Chelating Agents KW - Mice KW - Transferrin AB - We investigated the ability of compounds interfering with iron metabolism to inhibit the growth of Acinetobacter baumannii. Iron restriction with transferrin or 2,2-bipyridyl significantly inhibited A. baumannii growth in vitro. Gallium nitrate alone was moderately effective at reducing A. baumannii growth but became bacteriostatic in the presence of serum or transferrin. More importantly, gallium nitrate treatment reduced lung bacterial burdens in mice. The use of gallium-based therapies shows promise for the control of multidrug-resistant A. baumannii. Copyright © 2012, American Society for Microbiology. All Rights Reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9977cd26-d796-4047-baf1-b7d2ea873ed0 ER - TY - JOUR TI - Dopant depletion in the near surface region of thermally prepared silicon (100) in UHV DO - 10.1116/1.3694010 AU - Pitters, J.L. AU - Piva, P.G. AU - Wolkow, R.A. T2 - Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures SN - 1071-1023 VL - 30 IS - 2 SP - 21806 KW - Charging characteristics KW - Dopant atoms KW - Dopant concentrations KW - Dopant state KW - Doped sample KW - Hydrogen-terminated silicon KW - Hydrogen-terminated surfaces KW - Imaging characteristics KW - Near surface regions KW - Near-surface KW - Silicon (100) KW - Ultrahigh vacuum scanning tunneling microscopies KW - Arsenic KW - Carrier concentration KW - Dangling bonds KW - Electric charge KW - Hydrogen KW - Scanning tunneling microscopy KW - Semiconductor doping AB - Degenerately doped (arsenic) n-type hydrogen terminated silicon (100) samples were prepared using various heat treatments for ultrahigh vacuum scanning tunneling microscopy (STM) and spectroscopy (STS) analysis. Samples heat treated to 1050 C were found to have a consistent level of doping throughout the bulk and near surface regions. STS revealed tunneling through dopant states consistent with degenerately doped samples. SIMS profiling and HREELS measurements confirmed dopant and carrier concentrations, respectively. Samples heated to 1250 C were found to have a reduced concentration of dopants in the near surface region. STS measurements showed shifted I/V curves and the loss of tunneling through dopant states in the band gap, indicating reduced dopant concentrations. Observations were confirmed by SIMS and HREELS where depleted dopants and reduced carrier concentrations were measured. The effect of the varying surface dopant concentrations on the STM imaging characteristics of dangling bonds on hydrogen terminated surfaces was also investigated. Understanding the effect of thermal processing on near surface dopant atom concentrations will permit better control over equilibrium charge occupation and charging characteristics of dangling bond midgap states on H:silicon. © 2012 American Vacuum Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 16a1a2cb-22ae-494c-ae5b-c21128912fa5 ER - TY - JOUR TI - Optical and infrared photometry of globular clusters in NGC1399: Evidence for color-metallicity nonlinearity DO - 10.1088/0004-637X/746/1/88 AU - Blakeslee, J.P. AU - Cho, H. AU - Peng, E.W. AU - Ferrarese, L. AU - Jordn, A. AU - Martel, A.R. T2 - The Astrophysical Journal SN - 0004-637X VL - 746 IS - 1 SP - 88 AB - We combine new Wide Field Camera 3 IR Channel (WFC3/IR) F160W (H 160) imaging data for NGC1399, the central galaxy in the Fornax cluster, with archival F475W (g 475), F606W (V 606), F814W (I 814), and F850LP (z 850) optical data from the Advanced Camera for Surveys (ACS). The purely optical g 475 - I 814, V 606 - I 814, and g 475 - z 850 colors of NGC1399's rich globular cluster (GC) system exhibit clear bimodality, at least for magnitudes I 814 > 21.5. The optical-IR I 814 - H 160 color distribution appears unimodal, and this impression is confirmed by mixture modeling analysis. The V 606 - H 160 colors show marginal evidence for bimodality, consistent with bimodality in V 606 - I 814 and unimodality in I 814 - H 160. If bimodality is imposed for I 814 - H 160 with a double Gaussian model, the preferred blue/red split differs from that for optical colors; these "differing bimodalities" mean that the optical and optical-IR colors cannot both be linearly proportional to metallicity. Consistent with the differing color distributions, the dependence of I 814 - H 160 on g 475 - I 814 for the matched GC sample is significantly nonlinear, with an inflection point near the trough in the g 475 - I 814 color distribution; the result is similar for the I 814 - H 160 dependence on g 475 - z 850 colors taken from the ACS Fornax Cluster Survey. These g 475 - z 850 colors have been calibrated empirically against metallicity; applying this calibration yields a continuous, skewed, but single-peaked metallicity distribution. Taken together, these results indicate that nonlinear color-metallicity relations play an important role in shaping the observed bimodal distributions of optical colors in extragalactic GC systems. © 2012. The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3f5b19a2-f816-4716-ae98-19919c83d683 ER - TY - JOUR TI - Variability and change in the Canadian cryosphere DO - 10.1007/s10584-012-0470-0 AU - Derksen, C. AU - Smith, S.L. AU - Sharp, M. AU - Brown, L. AU - Howell, S. AU - Copland, L. AU - Mueller, D.R. AU - Gauthier, Y. AU - Fletcher, C.G. AU - Tivy, A. AU - Bernier, M. AU - Bourgeois, J. AU - Brown, R. AU - Burn, C.R. AU - Duguay, C. AU - Kushner, P. AU - Langlois, A. AU - Lewkowicz, A.G. AU - Royer, A. AU - Walker, A. T2 - Climatic Change SN - 0165-0009 VL - 115 IS - 1 SP - 59 EP - 88 KW - Canadian Arctic KW - Changing climate KW - Cryosphere KW - Data sets KW - Freshwater ice KW - Human activities KW - Ice shelves KW - International polar year KW - Mass loss KW - Northern regions KW - Observational research KW - Observing systems KW - Rate of change KW - Resource development KW - Retrieval algorithms KW - Satellite measurements KW - Sea ice extent KW - Snow cover extents KW - Spatial extent KW - Surface air temperatures KW - Temporal persistence KW - Permafrost KW - Sea ice KW - Snow KW - air temperature KW - algorithm KW - cryosphere KW - data set KW - human activity KW - ice breakup KW - ice shelf KW - natural resource KW - permafrost KW - research program KW - resource development KW - satellite imagery KW - sea ice KW - snow cover KW - Canada AB - During the International Polar Year (IPY), comprehensive observational research programs were undertaken to increase our understanding of the Canadian polar cryosphere response to a changing climate. Cryospheric components considered were snow, permafrost, sea ice, freshwater ice, glaciers and ice shelves. Enhancement of conventional observing systems and retrieval algorithms for satellite measurements facilitated development of a snapshot of current cryospheric conditions, providing a baseline against which future change can be assessed. Key findings include: 1. surface air temperatures across the Canadian Arctic exhibit a warming trend in all seasons over the past 40 years. A consistent pan-cryospheric response to these warming temperatures is evident through the analysis of multi-decadal datasets; 2. in recent years (including the IPY period) a higher rate of change was observed compared to previous decades including warming permafrost, reduction in snow cover extent and duration, reduction in summer sea ice extent, increased mass loss from glaciers, and thinning and break-up of the remaining Canadian ice shelves. These changes illustrate both a reduction in the spatial extent and mass of the cryosphere and an increase in the temporal persistence of melt related parameters. The observed changes in the cryosphere have important implications for human activity including the close ties of northerners to the land, access to northern regions for natural resource development, and the integrity of northern infrastructure. © 2012 UKCrown: Environment Canada; © Her Majesty the Queen in Right of Canada. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 723c3f52-149c-4642-bec6-96a3473d9d3d ER - TY - JOUR TI - Expression of single-domain antibodies in bacterial systems DO - 10.1007/978-1-61779-968-6-16 AU - Baral, T.N. AU - Arbabi-Ghahroudi, M. T2 - Methods in Molecular Biology SN - 1064-3745 SN - 9781617799679 VL - 911 SP - 257 EP - 275 KW - nanobody KW - recombinant antibody KW - hybrid protein KW - antibody library KW - antibody production KW - article KW - bacterium KW - culture medium KW - cytoplasm KW - Escherichia coli KW - expression vector KW - gene expression system KW - heavy chain KW - molecular cloning KW - nonhuman KW - phage display KW - priority journal KW - procedures KW - protein domain KW - protein expression KW - protein isolation KW - protein purification KW - reproducibility KW - antibody affinity KW - gene expression KW - gene library KW - gene vector KW - genetics KW - immunology KW - isolation and purification KW - metabolism KW - Antibody Affinity KW - Bacteria KW - Cloning, Molecular KW - Escherichia coli KW - Gene Expression KW - Gene Library KW - Genetic Vectors KW - Recombinant Fusion Proteins KW - Single-Domain Antibodies AB - In this chapter we describe in detail the current protocols that are used to express single-domain antibodies in bacteria. Bacteria are among the most common expression systems for expressing recombinant proteins. We present different approaches for carrying out periplasmic and cytoplasmic expression, as well as small-scale and large-scale expression. In addition, we discuss the advantages and possible drawbacks of each protocol. We present data related to expression vectors, expression conditions, methods of protein extraction and purification, and yield and purity analysis of sdAbs. We also highlight important points that need to be considered before sdAbs that have been expressed in bacteria are used either in vitro or in vivo. © 2012 Springer Science+Business Media, LLC. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2e30ee19-a743-4733-8516-a36d13203a8c ER - TY - JOUR TI - New concepts in silicon component design using sub wavelength structures DO - 10.1117/12.906785 AU - Molina-Fernandez, Iñigo AU - Halir, Robert AU - Ortega-Moñux, Alejandro AU - Zavargo-Peche, Luis AU - García, Sebastian Romero AU - Maese-Novo, Alejandro AU - Perez-Galacho, Diego AU - Wanguemert-Perez, Gonzalo AU - Cheben, Pavel AU - Xu, Dan-Xia T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Silicon Photonics VII, 22 January 2012 through 25 January 2012, San Francisco, CA SN - 0277-786X SN - 9780819489098 VL - 8266 SP - 82660E KW - Grating couplers KW - Multimode interference couplers KW - Polarization splitters KW - Silicon on insulator KW - Sub-wave length grating KW - SWG tapers KW - Design KW - Integrated optics KW - Optical filters KW - Photonic devices KW - Polarization KW - Refractive index KW - Waveguides KW - Waveguide filters AB - Subwavelength gratings (SWG) are periodically segmented waveguides with a pitch small enough to suppress diffraction. These waveguides can be engineered to implement almost any refractive between the refractive indices of the material that compose the waveguide, thereby opening novel design possibilities. In this communication we explore the use of SWGs in the design and optimization of a variety of integrated optical devices in the silicon-on-insulator platform: fiber-to-chip grating couplers, polarization splitters and high performance multimode interference couplers. We furthermore show that the dispersion properties of SWGs enable the design of novel filters, and discuss the design of low transitions between SWG waveguides of different characteristics. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2b7a6b9d-10d0-4ade-a1a1-766f9c88c7ed ER - TY - JOUR TI - Impact of room supply register location on predicted thermal comfort and IAQ AU - Ouazia, B. AU - MacDonald, I. AU - Thompson, A. AU - Booth, D. T2 - International Journal of Ventilation SN - 1473-3315 VL - 10 IS - 4 SP - 301 EP - 310 KW - Air heating KW - Air supply KW - Air Systems KW - Air temperature KW - Construction time KW - IAQ KW - Indoor air quality KW - New constructions KW - Residential KW - Tracer gas KW - Indoor air pollution KW - Thermal comfort KW - Phase interfaces AB - For residential forced air heating and cooling systems conventional thinking is that air supply registers should be located under exterior windows. There were good reasons for this in the past (primarily to counteract the cold downdraught from the window) but new construction standards (well-insulated walls, better glazing and air tight wall/window interface) mean that there is now less downdraught. Positioning the supply air register away from a window could have a large impact for new construction as duct lengths could be shortened (saving materials and construction time). This could also allow greater architectural freedom as the forced air system would not need to be ducted to the building perimeter. This paper presents results from experiments conducted in a new, well-constructed building to evaluate whether the supply registers can be moved away from the traditional location without impacting indoor air quality or predicted thermal comfort. The physical experiments showed that in both traditional and non-traditional placement: (1) there are minimal changes in predicted thermal comfort (a measure of thermal discomfort - vertical air temperature difference much lower than 3K), and (2) contaminant-removal effectiveness (a measure of indoor air quality) values were in the same range. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 32449639-4740-44a1-b18b-6ef217d50672 ER - TY - JOUR TI - The effect of total spinal anesthesia on cardiac function in a large animal model of brain death DO - 10.1139/Y2012-026 AU - Almoustadi, W.A. AU - Lee, T.W.R. AU - Klein, J. AU - Kumar, K. AU - Arora, R.C. AU - Tian, G. AU - Freed, D.H. T2 - Canadian Journal of Physiology and Pharmacology SN - 0008-4212 VL - 90 IS - 9 SP - 1287 EP - 1293 KW - adrenalin KW - catecholamine KW - noradrenalin KW - sodium chloride KW - adrenalin blood level KW - animal experiment KW - animal model KW - article KW - balloon catheter KW - blood pressure KW - brain death KW - catecholamine blood level KW - controlled study KW - heart function KW - heart rate KW - high performance liquid chromatography KW - intracerebral balloon tipped catheter KW - nonhuman KW - noradrenalin blood level KW - nuclear magnetic resonance imaging KW - priority journal KW - spinal anesthesia KW - swine KW - total spinal anesthesia AB - Brain death (BD) causes cardiac dysfunction in organ donors, attributable to the catecholamine storm that occurs with raised intracerebral pressure (ICP). However the direct contribution of the spinal sympathetics has not been well described. We examined the effect of total spinal anesthesia (TSA) on cardiac function in a large animal model of BD. Eighteen pigs were allocated to 3 experimental groups: Group 1, the saline-treated control group; Group 2, TSA administered prior to BD; and Group 3, TSA administered 30 min after BD. Inflation of an intracerebral balloon-tipped catheter was used to induce BD. Ventricular function was assessed using a pressure-volume loop catheter and magnetic resonance imaging. Serum catecholamine levels were assessed with high performance liquid chromatography. Inflation of the intracerebral balloon-tipped catheter was associated with a dramatic rise in heart rate and blood pressure, along with increased concentrations of serum epinephrine and norepinephrine. This phenomenon was not observed in Group 2. In Group 1, there was a significant decline in contractility, whereas groups 2 and 3 saw no change. Group 2 had greater contractile reserve than groups 1 and 3. Our data demonstrate the central role of spinal sympathetics in the hemodynamic response to raised ICP. Further work is required to determine the utility of TSA in reversing cardiac dysfunction in BD donors. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : da60b94b-60b8-4c7d-965a-c35db495e01e ER - TY - JOUR TI - Extracting functionally feed forward networks from a population of spiking neurons DO - 10.3389/fncom.2012.00086 AU - Vincent, K. AU - Tauskela, J.S. AU - Thivierge, J.-P. T2 - Frontiers in Computational Neuroscience SN - 1662-5188 IS - Oct-12 KW - AMPA-receptor KW - AS-links KW - Avalanche dynamics KW - Computational approach KW - Control cultures KW - Control mediums KW - Cortical neurons KW - Cultured cortical neurons KW - Directed links KW - Feed forward KW - Feed-forward network KW - Feedforward connections KW - Functional connection KW - Functional connectivity KW - Functional network KW - GABAA receptors KW - Multielectrode arrays KW - Neuronal circuits KW - NMDA receptor KW - Poisson model KW - Power-law KW - Schur decomposition KW - Spiking neuron KW - Theoretical models KW - Underlying dynamics KW - Dynamics KW - Neurons KW - Neural networks KW - animal cell KW - animal experiment KW - article KW - artificial neural network KW - cell structure KW - cellular distribution KW - controlled study KW - feedforward network KW - mathematical computing KW - mathematical model KW - nerve cell culture KW - nerve stimulation KW - nervous system function KW - neuromodulation KW - nonhuman KW - rat KW - spike wave AB - Neuronal avalanches are a ubiquitous form of activity characterized by spontaneous bursts whose size distribution follows a power-law. Recent theoretical models have replicated power-law avalanches by assuming the presence of functionally feedforward connections (FFCs) in the underlying dynamics of the system. Accordingly, avalanches are generated by a feedforward chain of activation that persists despite being embedded in a larger, massively recurrent circuit. However, it is unclear to what extent networks of living neurons that exhibit power-law avalanches rely on FFCs. Here, we employed a computational approach to reconstruct the functional connectivity of cultured cortical neurons plated on multielectrode arrays, and investigated whether pharmacologically-induced alterations in avalanche dynamics are accompanied by changes in FFCs. This approach begins by extracting a functional network of directed links between pairs of neurons, and then evaluates the strength of FFCs using Schur decomposition. In a first step, we examined the ability of this approach to extract FFCs from simulated spiking neurons. The strength of FFCs obtained in strictly feedforward networks diminished monotonically as links were gradually rewired at random. Next, we estimated the FFCs of spontaneously active cortical neuron cultures in the presence of either a control medium, a GABAA receptor antagonist (PTX), or an AMPA receptor antagonist combined with an NMDA receptor antagonist (APV/DNQX). The distribution of avalanche sizes in these cultures was modulated by this pharmacology, with a shallower power-law under PTX (due to the prominence of larger avalanches) and a steeper power-law under APV/DNQX (due to avalanches recruiting fewer neurons) relative to control cultures. The strength of FFCs increased in networks after application of PTX, consistent with an amplification of feed forward activity during avalanches. Conversely, FFCs decreased after application of APV/DNQX, consistent with fading feed forward activation. The observed alterations in FFCs provide experimental support for recent theoretical work linking power-law avalanches to the feed forward organization of functional connections in local neuronal circuits. © 2012 Vincent, Tauskela and Thivierge. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b7ac1a78-4e4b-4aa2-9a54-95f719f0a41b ER - TY - JOUR TI - Transition path times for nucleic acid folding determined from energy-landscape analysis of single-molecule trajectories DO - 10.1103/PhysRevLett.109.068102 AU - Neupane, K. AU - Ritchie, D.B. AU - Yu, H. AU - Foster, D.A.N. AU - Wang, F. AU - Woodside, M.T. T2 - Physical Review Letters SN - 0031-9007 VL - 109 IS - 6 SP - 68102 KW - Configurational energy KW - Critical events KW - Diffusion constant KW - DNA hairpin KW - Energy landscape KW - Folding reactions KW - Optical trap KW - Pseudo-knots KW - Riboswitches KW - RNA folding KW - Single-molecule KW - Structural transitions KW - Time spent KW - Transition paths KW - Transition time KW - Biopolymers KW - RNA KW - Molecules AB - The duration of structural transitions in biopolymers is only a fraction of the time spent searching diffusively over the configurational energy landscape. We found the transition time, τ TP, and the diffusion constant, D, for DNA and RNA folding using energy landscapes obtained from single-molecule trajectories under tension in optical traps. DNA hairpins, RNA pseudoknots, and a riboswitch all had τ TP∼10μs and D∼10 -13 -14m2/s, despite widely differing unfolding rates. These results show how energy-landscape analysis can be harnessed to characterize brief but critical events during folding reactions. © 2012 American Physical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : dcd92523-10e2-49c0-9036-af8a38273910 ER - TY - JOUR TI - Theory untangles the high-resolution infrared spectrum of the ortho-H 2-CO van der Waals complex DO - 10.1126/science.1221000 AU - Jankowski, P. AU - McKellar, A.R.W. AU - Szalewicz, K. T2 - Science SN - 0036-8075 VL - 336 IS - 6085 SP - 1147 EP - 1150 KW - computer KW - infrared radiation KW - infrared spectroscopy KW - precision KW - quantum mechanics KW - spectrum KW - article KW - energy KW - infrared spectroscopy KW - priority journal KW - quantum mechanics KW - theory validation KW - vibration AB - Rovibrational spectroscopy of molecules boasts extremely high precision, but its usefulness relies on the assignment of spectral features to corresponding quantum mechanical transitions. In the case of ortho-H 2-CO, a weakly bound complex abundant in the interstellar medium (although not yet observed there), the rather complex spectrum has been unexplained for more than a decade. We assigned this spectrum by comparison with a purely ab initio calculation. For most lines, agreement to within 0.01 centimeter-1 between experiment and theory was achieved. Our results show that the applicability of rovibrational spectroscopy can be extended with the assistance of high-accuracy quantum mechanical computations. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 97b602d4-2757-44f5-985a-e458f2fdd37e ER - TY - JOUR TI - Wavelength conversion via FWM in a silicon ring resonator at 10 Gb/s for DPSK signals AU - Li, F. AU - Pelusi, M. AU - Xu, D.-X. AU - Ma, R. AU - Janz, S. AU - Eggleton, B.J. AU - Moss, D.J. T2 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012 T3 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012, 6 May 2012 through 11 May 2012, San Jose, CA SN - 9781467318396 SP - 6326233 KW - 10 Gb/ S KW - All-optical wavelength conversion KW - DPSK signals KW - Error free operations KW - Silicon ring resonator KW - System penalty KW - Lasers KW - Light modulation KW - Optical frequency conversion KW - Four wave mixing AB - We demonstrate all-optical wavelength conversion at 10 Gb/s for differential phase-shift keyed (DPSK) data in the C-band, based on four-wave mixing (FWM) in a silicon ring resonator. Error-free operation with a system penalty of ∼ 4.1 dB at 10-9 BER is achieved. © 2012 OSA. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5283265b-46ba-419f-8a40-93b6c6562597 ER - TY - JOUR TI - METAGENassist: A comprehensive web server for comparative metagenomics DO - 10.1093/nar/gks497 AU - Arndt, D. AU - Xia, J. AU - Liu, Y. AU - Zhou, Y. AU - Guo, A.C. AU - Cruz, J.A. AU - Sinelnikov, I. AU - Budwill, K. AU - Nesbø, C.L. AU - Wishart, D.S. T2 - Nucleic Acids Research SN - 0305-1048 VL - 40 IS - W1 SP - W88 EP - W95 KW - RNA 16S KW - article KW - automation KW - bacterial genome KW - bacterium culture KW - classification KW - cluster analysis KW - comparative metagenomics KW - comparative study KW - computer program KW - controlled study KW - data processing KW - energy resource KW - environment KW - genetic database KW - genome size KW - host KW - intermethod comparison KW - Internet KW - metagenomics KW - nonhuman KW - nucleotide sequence KW - oxygen consumption KW - phenotype KW - population genetics KW - priority journal KW - publication KW - statistical analysis KW - taxonomy KW - temperature KW - web server KW - Bacteria KW - Data Interpretation, Statistical KW - Internet KW - Metagenomics KW - Phenotype KW - Software KW - Bacteria (microorganisms) AB - With recent improvements in DNA sequencing and sample extraction techniques, the quantity and quality of metagenomic data are now growing exponentially. This abundance of richly annotated metagenomic data and bacterial census information has spawned a new branch of microbiology called comparative metagenomics. Comparative metagenomics involves the comparison of bacterial populations between different environmental samples, different culture conditions or different microbial hosts. However, in order to do comparative metagenomics, one typically requires a sophisticated knowledge of multivariate statistics and/or advanced software programming skills. To make comparative metagenomics more accessible to microbiologists, we have developed a freely accessible, easy-to-use web server for comparative metagenomic analysis called METAGENassist. Users can upload their bacterial census data from a wide variety of common formats, using either amplified 16S rRNA data or shotgun metagenomic data. Metadata concerning environmental, culture, or host conditions can also be uploaded. During the data upload process, METAGENassist also performs an automated taxonomic-to-phenotypic mapping. Phenotypic information covering nearly 20 functional categories such as GC content, genome size, oxygen requirements, energy sources and preferred temperature range is automatically generated from the taxonomic input data. Using this phenotypically enriched data, users can then perform a variety of multivariate and univariate data analyses including fold change analysis, t-tests, PCA, PLS-DA, clustering and classification. To facilitate data processing, users are guided through a step-by-step analysis workflow using a variety of menus, information hyperlinks and check boxes. METAGENassist also generates colorful, publication quality tables and graphs that can be downloaded and used directly in the preparation of scientific papers. METAGENassist is available at http://www.metagenassist.ca. © 2012 The Author(s). DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1d2c18cb-7516-47f5-8240-efd2ba12b321 ER - TY - JOUR TI - The instrumentation program for the Thirty Meter Telescope DO - 10.1117/12.930500 AU - Simard, L. AU - Crampton, D. AU - Ellerbroek, B. AU - Boyer, C. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Ground-Based and Airborne Instrumentation for Astronomy IV, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491473 VL - 8446 SP - 84461F KW - Current status KW - Diffraction limited KW - Extremely Large Telescopes KW - Instrumentation programs KW - Observation planning KW - Operational concepts KW - Thirty Meter Telescope KW - Adaptive optics KW - Astronomy KW - Telescopes KW - Optical telescopes AB - An overview of the current status of the Thirty Meter Telescope (TMT) instrumentation program is presented. Science cases and operational concepts as well as their links to the instruments are continually revisited and updated through a series of workshops and conferences. Work on the three first-light instruments (WFOS IRIS, and IRMS) has made significant progress, and many groups in TMT partner communities are developing future instrument concepts. Other instrument-related subsystems are also receiving considerable attention given their importance to the scientific end-toend performance of the Observatory. As an example, we describe aspects of the facility instrument cooling system that are crucially important to successful diffraction-limited observations on an extremely large telescope. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0e8db93c-c23d-44e6-a9c8-d2a173df2b0e ER - TY - JOUR TI - Dark hole and planet detection: Laboratory results using the Self-Coherent Camera DO - 10.1117/12.926575 AU - Baudoz, P. AU - Mazoyer, J. AU - Mas, M. AU - Galicher, R. AU - Rousset, G. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Ground-Based and Airborne Instrumentation for Astronomy IV, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491473 VL - 8446 SP - 84468C KW - Active correction KW - Angular separation KW - Coronagraph KW - Coronagraphy KW - Deformable mirrors KW - Direct imaging KW - Exoplanet KW - Extra solar planets KW - Extremely Large Telescopes KW - Focal Plane KW - Ground based KW - High contrast KW - High contrast imaging KW - Near-IR KW - Optical defects KW - Planet detection KW - Planet finders KW - Post processing KW - Reference image KW - Scientific applications KW - Speckle noise KW - Wavefront correction KW - Wavefront quality KW - Astronomy KW - Cameras KW - Laser pulses KW - Optical telescopes KW - Image processing AB - Direct imaging and low-resolution spectroscopy of extrasolar planets are exciting but challenging scientific applications of coronagraphy. While the angular separation is well within the reach of actual telescope in the near IR or visible, the planet-star contrast (from 10-6 to 10-10) requires wavefront quality and stability hard to reach even with a well-polished space telescope. Several solutions have been proposed to tackle the speckle noise introduced by the residual optical defects. While some concepts rely only on active wavefront correction using deformable mirror, other techniques are based on post-processing and subtract a reference image recorded sometimes simultaneously with the science image. One interesting solution is to choose a concept that allows both active correction and post-processing of high contrast coronagraphic images. This is the case of the Self Coherent Camera (SCC), which has been proposed for the project of space coronagraph SPICES and for the ground-based planet finder EPICS studied for the European Extremely Large Telescope. After recalling the SCC principle, we present both monochromatic and modest bandwidth (2%) experimental results of Dark Hole in the focal plane using a SCC. Example of a post-processing result with SCC is also given to emphasize the interest of combining it with active correction. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ab950adc-e29e-47d4-bd1a-4a6c6f170b2a ER - TY - JOUR TI - Gemini high-resolution optical spectrograph conceptual design DO - 10.1117/12.926690 AU - Szeto, K. AU - McConnachie, A. AU - Anthony, A. AU - Bohlender, D. AU - Crampton, D. AU - Desaulniers, P. AU - Dunn, J. AU - Hardy, T. AU - Hill, A. AU - Monin, D. AU - Pazder, J. AU - Schwab, C. AU - Spano, P. AU - Starkenburg, E. AU - Thibault, S. AU - Walker, G. AU - Venn, K. AU - Zhang, H. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Ground-Based and Airborne Instrumentation for Astronomy IV, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491473 VL - 8446 SP - 844635 KW - CCD detectors KW - Design trades KW - Echelle KW - Instrument software KW - Pick-off KW - White pupil relay KW - Astrophysics KW - Commerce KW - Conceptual design KW - Fibers KW - Motion control KW - Optical resolving power KW - Spectrographs KW - Instruments AB - A multiplexed moderate resolution (R = 34,000) and a single object high resolution (R = 90,000) spectroscopic facility for the entire 340-950nm wavelength region has been designed for Gemini. The result is a high throughput, versatile instrument that will enable precision spectroscopy for decades to come. The extended wavelength coverage for these relatively high spectral resolutions is achieved by use of an Echelle grating with VPH cross-dispersers and for the R = 90,000 mode utilization of an image slicer. The design incorporates a fast, efficient, reliable system for acquiring targets over the7 arcmin field of Gemini. This paper outlines the science case development and requirements flow-down process that leads to the configuration of the HIA instrument and describes the overall GHOS conceptual design. In addition, this paper discusses design trades examined during the conceptual design study instrument group of the Herzberg Institute of Astrophysics has been commissioned by the Gemini Observatory as one of the three competing organizations to conduct a conceptual design study for a new Gemini High-Resolution Optical Spectrograph (GHOS). This paper outlines the science case development and requirements flow-down process that leads to the configuration of the HIA instrument and describes the overall GHOS conceptual design. In addition, this paper discusses design trades examined during the conceptual design study. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 25de7a60-cae3-4c95-8999-f930ced095f3 ER - TY - JOUR TI - Nonlinear behaviour of steel-concrete composite bridges: Finite element modelling and experimental verification DO - 10.1139/L11-124 AU - Razaqpur, A.G. AU - Nofal, M. AU - Shedid, M. AU - Esfandiari, A. T2 - Canadian Journal of Civil Engineering SN - 0315-1468 VL - 39 IS - 2 SP - 191 EP - 202 KW - Analysis KW - Composite KW - Finite Element KW - Load distributions KW - Reinforced KW - Bridges KW - Composite bridges KW - Concretes KW - Loading KW - Nonlinear analysis KW - Software testing KW - Steel KW - Finite element method KW - accuracy assessment KW - bridge KW - finite element method KW - loading KW - nonlinearity KW - reinforced concrete KW - steel structure KW - structural analysis AB - To ensure public safety, existing bridges are often evaluated for their load-bearing capacity. Realistic evaluation must take into account the actual nonlinear stress-strain characteristics of the bridge materials and the interaction among its structural components at all stages of loading up to failure. The finite element method is particularly suitable for this type of analysis, but nonlinear finite element formulations involve many assumptions that must be verified before any practical application. In this study, the accuracy of a nonlinear finite element program developed by the authors for the analysis of composite steel-concrete bridges is checked by comparing its results with experimental data from simply supported and continuous beams tested by others and from a 1/3 scale multi-girder composite bridge tested by the authors. Good agreement is observed between the measured and the computed load-deflection responses and strains at all stages of loading up to the maximum load, which demonstrates the accuracy of the finite element formulation and the validity of its assumptions. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6350706f-ad8d-4d3f-a176-463509828866 ER - TY - JOUR TI - Development of robust control law for active buffeting load alleviation of smart fin structures AU - Chen, Y. AU - Ulker, F.D. AU - Wickramasinghe, V. AU - Zimcik, D. T2 - 23rd International Conference on Adaptive Structures and Technologies, ICAST 2012 T3 - 23rd International Conference on Adaptive Structures and Technologies, ICAST 2012, 11 October 2012 through 13 October 2012, Nanjing KW - Buffeting load KW - Development strategies KW - Low frequency range KW - Model uncertainties KW - Parametric uncertainties KW - Structured singular values KW - Synthesis techniques KW - Vertical fin KW - Buffeting KW - Dynamic models KW - Fins (heat exchange) KW - Modal analysis KW - Robust control KW - Uncertainty analysis KW - Vibration control KW - Vertical stabilizers AB - Aerodynamic buffeting load can lead to pre-mature fatigue damage of aircraft vertical fin structures. This paper presents a robust control law development strategy for active buffeting load alleviation of a smart fin structure. The impact of aerodynamic loads on the modeling uncertainties of the smart fin was investigated through extensive wind tunnel tests. Test results revealed that the airflow introduced higher damping ratio and caused frequency shift to the vibration modes. These aerodynamic effects may adversely affect the performance and robustness of active control laws. Based on the observations, the structured singular value synthesis technique was used to develop a robust control law for the smart fin using a truncated baseline dynamic model. A parametric uncertainty block was introduced to account for the changes in the modal parameters of the baseline dynamic model due to the aerodynamic effects. An additive uncertainty block was included to account for the un-modeled higher order vibration modes as well as the modeling errors in the low frequency range. The robust performance of the control law was demonstrated through simulations as well as extensive closed-loop control experiments in the wind tunnel using various free airstreams and vortical airflows. This provided a verified control law design strategy for active buffeting alleviation applications. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 150ab3b2-42b5-4262-bb79-19c262f260b4 ER - TY - JOUR TI - Flocculation of cellulose nanocrystals by adsorbing and non-adsorbing polymers AU - Boluk, Y. AU - Danumah, C. AU - Khalili, Z. T2 - TAPPI International Conference on Nanotechnology for Renewable Materials 2012 T3 - TAPPI International Conference on Nanotechnology for Renewable Materials 2012, 4 June 2012 through 7 June 2012, Montreal, QC SN - 9781627480536 SP - 155 EP - 167 DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6aa29f21-98fc-441d-8ff3-4f232af6ba3f ER - TY - JOUR TI - Residual strain distribution around a fatigue-crack tip determined by neutron diffraction DO - 10.4028/www.scientific.net/MSF.706-709.1685 AU - Huang, E.-W. AU - Li, K.-W. AU - Lee, S.Y. AU - Woo, W. AU - Ding, Y.-S. AU - Tsay, L.-W. AU - Chen, C.-H. T2 - Materials Science Forum T3 - 7th International Conference on Processing and Manufacturing of Advanced Materials, THERMEC'2011, 1 August 2011 through 5 August 2011, Quebec City, QC SN - 0255-5476 SN - 9783037853030 VL - 706-709 SP - 1685 EP - 1689 KW - 304L stainless steel KW - Compact tension KW - Cyclic loadings KW - Driving forces KW - Fatigue crack growth mechanism KW - Life-prediction methodology KW - Multiaxiality KW - Residual strains KW - Spatial resolution KW - Crack propagation KW - Crack tips KW - Fatigue crack propagation KW - Fatigue of materials KW - Growth (materials) KW - Neutron diffraction KW - Neutrons KW - Orthogonal functions KW - Plasticity testing KW - Poisson distribution KW - Stainless steel KW - Strain KW - Factor analysis KW - Crack closure KW - Crack tips AB - An analysis of residual stress, one of the contributory factors to the crack tip driving force, is extremely important to probe the fatigue crack growth mechanism and to further develop the life prediction methodology. Since fatigue crack growth is governed by crack-tip plasticity and crack closure in the wake of the crack tip, the investigation of residual stain/stress field in both behind and in front of the crack tip is crucial. In the current work, a 304L stainless steel compact-tension specimen is pre-cracked under constant-amplitude cyclic loading. Neutron diffraction is employed to directly measure the three orthogonal residual strain fields with 1-mm spatial resolution as a function of distance from the crack tip. The mapping results show that the three orthogonal residual-strain distributions around the crack tip depend on the stress multiaxiality, not following a single Poisson relationship to each axis. © 2012 Trans Tech Publications, Switzerland. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 791b62e1-5985-4923-a175-d1f15b06032b ER - TY - JOUR TI - Application of dielectric barrier discharge to improve the flashback limit of a lean premixed dump combustor DO - 10.1115/1.4004237 AU - Versailles, P. AU - Chishty, W.A. AU - Vo, H.D. T2 - Journal of Engineering for Gas Turbines and Power SN - 0742-4795 VL - 134 IS - 3 SP - 31501 KW - Air flow-rate KW - Combustion zones KW - Core flow KW - Dielectric barrier discharges KW - Dump combustor KW - Equivalence ratios KW - Experimental setup KW - Flame propagation KW - High temperature KW - Ionic wind KW - Low Power KW - Natural gas-air mixture KW - Novel applications KW - Operating condition KW - Premixed KW - Syn-gas KW - Velocity profiles KW - Actuators KW - Combustion KW - Dielectric devices KW - Flow control KW - Flow rate KW - Fuels KW - Gas turbines KW - Hydrogen KW - Natural gas KW - Quartz KW - Rate constants KW - Synthesis gas KW - Combustors AB - In recent years, lean-premixed (LP) combustors have been widely studied due to their potential to reduce NO x emissions in comparison to diffusion type combustors. However, the fact that the fuels and oxidizers are mixed upstream of the combustion zone makes LP type of combustors a candidate for upstream flame propagation (i.e., flashback) in the premixer that is typically not designed to sustain high temperatures. Moreover, there has been a recent demand for fuel-flexible gas turbines that can operate on hydrogen-enriched fuels like Syngas. Combustors originally designed for slower kinetics fuels like natural gas can potentially encounter flashback if operated with faster burning fuels like those containing hydrogen as a constituent. There exists a clear need in fuel-flexible lean-premixed combustors to control flashback that will not only prevent costly component damage but will also enhance the operability margin of engines. A successful attempt has been made to control flashback in an atmospheric LP combustor, burning natural gas-air mixtures, via the application of dielectric barrier discharge (DBD). A low-power DBD actuator was designed, fabricated and integrated into a premixer made out of quartz. The actuator was tuned to produce a low magnitude ionic wind with an intention to modify the velocity profile in the premixer. Flashback conditions were created by decreasing the air flow rate while keeping the fuel flow rate constant. Within this experimental setup, flashback happened in the core flow along the axis of the cylindrical premixer. Results show that the utilization of the DBD delays the occurrence of flashback to higher equivalence ratios. Improvements as high as about 5 of the flashback limit have been obtained without compromising the blowout limit. It is anticipated that this novel application of DBD will lead to future demonstrations of the concept under realistic gas turbine operating conditions. © 2012 Her Majesty the Queen in Right of Canada. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0272fde6-2586-4798-8161-87949ff6d302 ER - TY - JOUR TI - A literature review of the numerical analysis of abdominal aortic aneurysms treated with endovascular stent grafts DO - 10.1155/2012/820389 AU - Roy, D. AU - Kauffmann, C. AU - Delorme, S. AU - Lerouge, S. AU - Cloutier, G. AU - Soulez, G. T2 - Computational and Mathematical Methods in Medicine SN - 1748-670X VL - 2012 SP - 820389 KW - abdominal aorta aneurysm KW - aneurysm rupture KW - aorta wall KW - artery calcification KW - artery compliance KW - biomechanics KW - blood flow KW - blood rheology KW - endovascular aneurysm repair KW - finite element analysis KW - laminar flow KW - mathematical computing KW - mathematical model KW - review KW - shear stress KW - stress strain relationship KW - virtual reality KW - viscoelasticity KW - Young modulus KW - aorta KW - biological model KW - blood vessel KW - blood vessel transplantation KW - calcinosis KW - catheter KW - computer simulation KW - flow kinetics KW - hemodynamics KW - human KW - instrumentation KW - mechanical stress KW - methodology KW - pathology KW - risk KW - stent KW - theoretical model KW - Aorta KW - Aortic Aneurysm, Abdominal KW - Biomechanics KW - Blood Vessel Prosthesis Implantation KW - Blood Vessels KW - Calcinosis KW - Catheters KW - Computer Simulation KW - Finite Element Analysis KW - Hemodynamics KW - Humans KW - Models, Cardiovascular KW - Models, Theoretical KW - Rheology KW - Risk KW - Stents KW - Stress, Mechanical AB - The purpose of this paper is to present the basic principles and relevant advances in the computational modeling of abdominal aortic aneurysms and endovascular aneurysm repair, providing the community with up-to-date state of the art in terms of numerical analysis and biomechanics. Frameworks describing the mechanical behavior of the aortic wall already exist. However, intraluminal thrombus nonhomogeneous structure and porosity still need to be well characterized. Also, although the morphology and mechanical properties of calcifications have been investigated, their effects on wall stresses remain controversial. Computational fluid dynamics usually assumes a rigid artery wall, whereas fluid-structure interaction accounts for artery compliance but is still challenging since arteries and blood have similar densities. We discuss alternatives to fluid-structure interaction based on dynamic medical images that address patient-specific hemodynamics and geometries. We describe initial stresses, elastic boundary conditions, and statistical strength for rupture risk assessment. Special emphasis is accorded to workflow development, from the conversion of medical images into finite element models, to the simulation of catheter-aorta interactions and stent-graft deployment. Our purpose is also to elaborate the key ingredients leading to virtual stenting and endovascular repair planning that could improve the procedure and stent-grafts. © 2012 David Roy et al. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 938ff2bb-ba27-491a-bdf6-91a91786726d ER - TY - JOUR TI - A blind detection of a large, complex, Sunyaev-Zel'dovich structure DO - 10.1111/j.1365-2966.2012.20970.x AU - Shimwell, T.W. AU - Barker, R.W. AU - Biddulph, P. AU - Bly, D. AU - Boysen, R.C. AU - Brown, A.R. AU - Brown, M.L. AU - Clementson, C. AU - Crofts, M. AU - Culverhouse, T.L. AU - Czeres, J. AU - Dace, R.J. AU - Davies, M.L. AU - D'Alessandro, R. AU - Doherty, P. AU - Duggan, K. AU - Ely, J.A. AU - Felvus, M. AU - Feroz, F. AU - Flynn, W. AU - Franzen, T.M.O. AU - Geisbüsch, J. AU - Génova-Santos, R. AU - Grainge, K.J.B. AU - Grainger, W.F. AU - Hammett, D. AU - Hobson, M.P. AU - Holler, C.M. AU - Hurley-Walker, N. AU - Jilley, R. AU - Kaneko, T. AU - Kneissl, R. AU - Lancaster, K. AU - Lasenby, A.N. AU - Marshall, P.J. AU - Newton, F. AU - Norris, O. AU - Northrop, I. AU - Odell, D.M. AU - Olamaie, M. AU - Perrott, Y.C. AU - Pober, J.C. AU - Pooley, G.G. AU - Pospieszalski, M.W. AU - Quy, V. AU - Rodríguez-Gonzálvez, C. AU - Saunders, R.D.E. AU - Scaife, A.M.M. AU - Schammel, M.P. AU - Schofield, J. AU - Scott, P.F. AU - Shaw, C. AU - Smith, H. AU - Titterington, D.J. AU - Velić, M. AU - Waldram, E.M. AU - West, S. AU - Wood, B.A. AU - Yassin, G. AU - Zwart, J.T.L. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 423 IS - 2 SP - 1463 EP - 1473 AB - We present an interesting Sunyaev-Zel'dovich (SZ) detection in the first of the Arcminute Microkelvin Imager (AMI) 'blind', degree-square fields to have been observed down to our target sensitivity of. In follow-up deep pointed observations the SZ effect is detected with a maximum peak decrement greater than eight times the thermal noise. No corresponding emission is visible in the ROSAT all-sky X-ray survey and no cluster is evident in the Palomar all-sky optical survey. Compared with existing SZ images of distant clusters, the extent is large (≈10arcmin) and complex; our analysis favours a model containing two clusters rather than a single cluster. Our Bayesian analysis is currently limited to modelling each cluster with an ellipsoidal or spherical β model, which does not do justice to this decrement. Fitting an ellipsoid to the deeper candidate we find the following. (a) Assuming that the Evrard et al. approximation to Press & Schechter correctly gives the number density of clusters as a function of mass and redshift, then, in the search area, the formal Bayesian probability ratio of the AMI detection of this cluster is 7.9 × 10 4:1; alternatively assuming Jenkins et al. as the true prior, the formal Bayesian probability ratio of detection is 2.1 × 10 5:1. (b) The cluster mass is (c) Abandoning a physical model with number density prior and instead simply modelling the SZ decrement using a phenomenological β model of temperature decrement as a function of angular distance, we find a central SZ temperature decrement of K - this allows for cosmic microwave background primary anisotropies, receiver noise and radio sources. We are unsure if the cluster system we observe is a merging system or two separate clusters. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 665e04e8-51d1-4f35-b944-4acbe55e99f3 ER - TY - JOUR TI - Optical design of a Cassegrain mounted AO relay for Imaka DO - 10.1117/12.925859 AU - Pazder, J. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Adaptive Optics Systems III, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491480 VL - 8447 SP - 84473U KW - Astronomical instrumentation KW - Atmospheric dispersion KW - Deformable mirrors KW - Double pass KW - Encircled energy KW - Field of views KW - Ground-layer adaptive optics KW - Image performance KW - Imaging performance KW - Takeshi ADC KW - Adaptive optics KW - Atmospheric movements KW - Optical telescopes KW - Telescopes KW - Optical design AB - The Imaka project is a ground layer adaptive optics system proposed for the Canada-France-Hawaii Telescope. This paper presents the optical design of a Cassegrain mounted ground layer adaptive optics system with a 0.8 degree field of view for Imaka. The design incorporates a Takeshi concentric ADC and a f/8 to f/5.7 reducer. This is followed with a novel double pass system to image the pupil on a 300mm mildly concave deformable mirror and re-image the system on the detector. The design meets the required 0.15" 80% encircled energy image performance, including correction for atmospheric dispersion. The optical design is presented with the predicted imaging performance. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e6ba56aa-3a28-4ddb-a913-47528bf51694 ER - TY - JOUR TI - Preserving the photometric integrity of companions in high-contrast imaging observations using locally optimized combination of images DO - 10.1117/12.926247 AU - Maire, J. AU - Gagné, J. AU - Lafrenière, D. AU - Doyon, R. AU - Graham, J.R. AU - Véran, J.-P. AU - Poyneer, L.A. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Adaptive Optics Systems III, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491480 VL - 8447 SP - 844760 KW - Direct imaging KW - Exo-planets KW - Extra solar planets KW - High contrast imaging KW - Planet formation KW - Speckle suppression KW - Techniques KW - Data processing KW - Image processing KW - Optimization KW - Photometry AB - Direct imaging and spectroscopy can advance our understanding of planet formation and migration through the detection and characterization of extrasolar planets on wide orbits. Accurate photometry and astrometry of detected companions are of crucial importance to derive the planet physical properties.We present an extension of the Locally optimized combination of images (LOCI) method to measure the highest-fidelity photometry as well as accurate astrometry of detected companions. This algorithm is also generalized to Integral-Field Spectrograph (IFS) data processing, giving advantages of a simultaneous angular and spectral differential imaging reduction, retrieving high-fidelity spectra from PSF-subtracted cubes. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c6a10c83-9739-4280-baa9-023882980e2b ER - TY - JOUR TI - The JWST Fine Guidance Sensor (FGS) and Near-Infrared Imager and Slitless Spectrograph (NIRISS) DO - 10.1117/12.926578 AU - Doyon, R. AU - Hutchings, J. AU - Beaulieu, M. AU - Albert, L. AU - Lafrenière, D. AU - Willott, C. AU - Touahri, D. AU - Rowlands, N. AU - Maszkiewicz, M. AU - Fullerton, A. AU - Volk, K. AU - Martel, A. AU - Chayer, P. AU - Sivaramakrishnan, A. AU - Abraham, R. AU - Ferrarese, L. AU - Jayawardhana, R. AU - Johnstone, D. AU - Meyer, M. AU - Pipher, J. AU - Sawicki, M. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491435 VL - 8442 SP - 84422R KW - Angular separation KW - Broadband filters KW - Broadband imaging KW - Exo-planets KW - Field of views KW - Fine guidance sensors KW - High contrast imaging KW - Infra-red cameras KW - Interferometric imaging KW - JWST instrumentation KW - Near Infrared KW - Point sources KW - Sparse aperture KW - Wavelength coverage KW - Wavelength ranges KW - Wide-field KW - Infrared devices KW - Interferometry KW - Millimeter waves KW - Sensors KW - Source separation KW - Space telescopes KW - Spectrographs KW - Spectroscopy KW - Instruments AB - The Fine Guidance Sensor (FGS) is one of the four science instruments on board the JamesWebb Space Telescope (JWST). FGS features two modules: an infrared camera dedicated to fine guiding of the observatory and a science camera module, the Near-Infrared Imager and Slitless Spectrograph (NIRISS) covering the wavelength range between 0.7 and 5.0 μm with a field of view of 2.2'×2.2'. NIRISS has four observing modes: 1) broadband imaging featuring seven of the eight NIRCam broadband filters, 2) wide-field slitless spectroscopy at a resolving power of ̃150 between 1 and 2.5 μm, 3) single-object cross-dispersed slitless spectroscopy enabling simultaneous wavelength coverage between 0.7 and 2.5 μm at R ̃ 660, a mode optimized for transit spectroscopy of relatively bright (J > 7) stars and, 4) sparse aperture interferometric imaging between 3.8 and 4.8 μm enabling high- contrast (̃ 10-4) imaging of M < 8 point sources at angular separations between 70 and 500 milliarcsec. This paper presents an overview of the FGS/NIRISS design with a focus on the scientific capabilities and performance offered by NIRISS. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 33026ae4-994b-402b-adb3-9dfae33c4c8a ER - TY - JOUR TI - Stable hydrogen storage cycling in magnesium hydride, in the range of room temperature to 300°C, achieved using a new bimetallic Cr-V nanoscale catalyst DO - 10.1021/jp211254k AU - Zahiri, B. AU - Danaie, M. AU - Tan, X. AU - Amirkhiz, B.S. AU - Botton, G.A. AU - Mitlin, D. T2 - The Journal of Physical Chemistry C SN - 1932-7447 VL - 116 IS - 4 SP - 3188 EP - 3199 KW - Core shell KW - Driving forces KW - Hydrogen absorption KW - Hydrogen sorption KW - Hydrogen uptake KW - Magnesium hydride KW - matrix KW - Metal hydride systems KW - Nano scale KW - Nanoscale catalysts KW - Nanoscale-dispersion KW - Powder samples KW - Room temperature KW - TEM analysis KW - Transmission electron KW - Activation energy KW - Catalysts KW - Desorption KW - Hydrides KW - Hydrogen KW - Hydrogen storage KW - Hydrogenation KW - Magnesium KW - Nanotechnology KW - Transmission electron microscopy KW - Vanadium KW - Chromium AB - We created a bimetallic chromium vanadium hydrogen sorption catalyst for magnesium hydride (MgH 2). The catalyst allows for significant room-temperature hydrogen uptake, over 10 cycles, at absorption pressures as low as 2 bar. This is something that has never been previously achieved. The catalyst also allowed for ultrarapid and kinetically stable hydrogenation cycling (over 225 cycles) at 200 and at 300 °C. Transmission electron microscopy analysis of the postcycled samples revealed a nanoscale dispersion of Cr-V nanocrystallites within the Mg or MgH 2 matrix. TEM analysis of the partially absorbed specimens revealed that even at a high absorption pressure, that is, a high driving force, relatively few hydride nuclei are formed at the surface of the pre-existing magnesium, ruling out the presence of any contracting volume (also termed contracting envelope or core shell) type growth. HRTEM of the cycled and desorbed powder sample demonstrated that the bcc Cr-V phase is crystalline and nanoscale. We experimentally demonstrated that the activation energy for hydrogen absorption is not constant but rather evolves with the driving force. This finding sheds new insight regarding the origins of the wide discrepancy in the literature - reported values of the hydrogenation activation energy in magnesium hydride and in related metal hydride systems. © 2011 American Chemical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d49b1e06-2ede-4d85-9b90-a47a21a7e821 ER - TY - JOUR TI - A large group of asymptotic giant branch stars in the disk of M31: A missing piece of the puzzle? DO - 10.1088/2041-8205/749/1/L7 AU - Davidge, T.J. T2 - The Astrophysical Journal Letters SN - 2041-8205 VL - 749 IS - 1 SP - L7 AB - We examine the properties of a stellar grouping that is ∼3.5kpc to the northeast of the center of M31. This structure has (1) a surface brightness that is lower than the surrounding disk, (2) a more-or-less round appearance, (3) a size of ∼300 arcsec (∼1kpc), and (4) an integrated brightness K = 6.5. It is populated by stars with ages ≥100Myr and J - K colors that tend to be bluer than those of stars in the surrounding disk. Comparisons with model luminosity functions suggest that the star formation rate in this object has changed twice in the past few hundred Myr. Fitting a Sérsic function to the light profile reveals a power-law index and effective surface brightness that are similar to those of dwarf galaxies with the same integrated brightness. Two possible origins for this object are considered: (1) it is a heretofore undiscovered satellite of M31 that is seen against/in/through the M31 disk or (2) it is a fossil star-forming region in the M31 disk. © 2012. The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c372f741-772c-4a3e-842a-b95c59c55f30 ER - TY - JOUR TI - Electro-deposition and dissolution of MnO2 on a graphene composite electrode for its utilization in an aqueous based hybrid supercapacitor DO - 10.1149/2.064208jes AU - Perret, P.G. AU - Malenfant, P.R.L. AU - Bock, C. AU - MacDougall, B. T2 - Journal of the Electrochemical Society SN - 0013-4651 VL - 159 IS - 9 SP - A1554 EP - A1561 KW - Aqueous electrolyte KW - Charge/discharge cycle KW - Electrode reactions KW - Electrodissolution KW - Graphene composites KW - High surface area KW - Hybrid supercapacitors KW - Potential windows KW - Capacitors KW - Deposition KW - Dissolution KW - Electrolytes KW - Graphene KW - Hybrid systems KW - Manganese oxide AB - The electro-deposition and dissolution of MnO2 is studied for its potential utilization in hybrid supercapacitors. A commercially available graphene powder is used as high surface area substrate and capacitive type electrode. An aqueous electrolyte composed of 0.5 M H2SO4 + 0.5 M MnSO4 is used. The deposition-dissolution reaction of MnO2 is shown to provide the bulk of the charge storable in the battery type electrode. Furthermore, the potential window of stability of this electrode reaction is compatible with the aqueous electrolyte. Two complete systems were assembled and tested for their charge/discharge behavior. It is shown that energy and power densities of 25 Wh kg-1 and 980 W kg -1, respectively, can be achieved for at least 5000 cycles. Limitations of the system in terms of cycle numbers and electrolyte volume are discussed in more detail. The electrolyte volume to electrode mass ratio is shown to be a critical factor in determining the charge/discharge cycle number of the device. This is believed to be due to the fact that the efficiency of the MnO2 electro-dissolution/deposition process is less than 100%. This, in turn, could result in gradual pH changes and a lower Mn2+ concentration in the electrolyte during continues charging and discharging. This eventually results in lowering the energy and power density of the system. However, it is shown that an energy density of 25 Wh kg-1 is achievable, thus being comparable with similar hybrid systems. © 2012 The Electrochemical Society. All right reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4fb5ba18-4d3a-4ae1-ba58-c994bc0d9516 ER - TY - JOUR TI - Comparison of spatial working memory in children with prenatal alcohol exposure and those diagnosed with ADHD; A functional magnetic resonance imaging study DO - 10.1186/1866-1955-4-12 AU - Malisza, K.L. AU - Buss, J.L. AU - Bruce Bolster, R. AU - de Gervai, P.D. AU - Woods-Frohlich, L. AU - Summers, R. AU - Clancy, C.A. AU - Chudley, A.E. AU - Longstaffe, S. T2 - Journal of Neurodevelopmental Disorders SN - 1866-1947 VL - 4 IS - 1 KW - atomoxetine KW - fluoxetine KW - olanzapine KW - quetiapine KW - risperidone KW - adolescent KW - alcohol related neurodevelopmental disorder KW - article KW - attention deficit disorder KW - child KW - comorbidity KW - conduct disorder KW - controlled study KW - depression KW - developmental disorder KW - diffusion tensor imaging KW - female KW - fetal alcohol syndrome KW - functional magnetic resonance imaging KW - human KW - learning disorder KW - major clinical study KW - male KW - neuropsychological test KW - occipital cortex KW - oppositional defiant disorder KW - posterior parietal cortex KW - prefrontal cortex KW - prenatal exposure KW - psychologic assessment KW - psychosocial disorder KW - school child KW - spatial memory KW - task performance KW - white matter KW - working memory AB - Background Alcohol related neurodevelopmental disorder (ARND) falls under the umbrella of fetal alcohol spectrum disorder (FASD), but individuals do not demonstrate the facial characteristics associated with fetal alcohol syndrome (FAS), making diagnosis difficult. While attentional problems in ARND are similar to those found in attentiondeficit/ hyperactivity disorder (ADHD), the underlying impairment in attention pathways may be different. Methods Functional magnetic resonance imaging (fMRI) of a working memory (1-back) task of 63 children, 10 to 14 years old, diagnosed with ARND and ADHD, as well as typically developing (TD) controls, was conducted at 3 T. Diffusion tensor imaging (DTI) data were also acquired. Results Activations were observed in posterior parietal and occipital regions in the TD group and in dorsolateral prefrontal and posterior parietal regions in the ARND group, whereas the ADHD group activated only dorsolateral prefrontal regions, during the working memory component of the task (1-back minus 0-back contrast). The increases in frontal and parietal activity were significantly greater in the ARND group compared to the other groups. This increased activity was associated with reduced accuracy and increased response time variability, suggesting that ARND subjects exert greater effort to manage short-term memory load. Significantly greater intra-subject variability, demonstrated by fMRI region-of-interest analysis, in the ADHD and ARND groups compared to the TD group suggests that momentto- moment lapses in attention contributed to their poorer task performance. Differences in functional activity in ARND subjects with and without a diagnosis of ADHD resulted primarily from reduced activation by the ARND/ADHD + group during the 0-back task. In contrast, children with ADHD alone clearly showed reduced activations during the 1-back task. DTI analysis revealed that the TD group had significantly higher total tract volume and number of fibers than the ARND group. These measures were negatively correlated with errors on the 1-back task, suggesting a link between white matter integrity and task performance. Conclusions fMRI activations suggest that the similar behavior of children with ARND and ADHD on a spatial working memory task is the result of different cognitive events. The nature of ADHD in children with ARND appears to differ from that of children with ADHD alone. © 2012 Malisza et al. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 076ab1cb-e45a-4d8e-b4cc-becd3b7001a0 ER - TY - JOUR TI - Trajectory learning for robot programming by demonstration using hidden markov model and dynamic time warping DO - 10.1109/TSMCB.2012.2185694 AU - Vakanski, A. AU - Mantegh, I. AU - Irish, A. AU - Janabi-Sharifi, F. T2 - IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics SN - 1083-4419 VL - 42 IS - 4 SP - 6166903 SP - 1039 EP - 1052 KW - Complex trajectories KW - Dynamic time warping KW - Dynamic time warping algorithms KW - Keypoints KW - Programming by demonstration KW - Robot programming by demonstration KW - Smoothing spline KW - Weighting coefficient KW - Hidden Markov models KW - Programmable robots KW - Robot programming KW - Robotics KW - Trajectories AB - The main objective of this paper is to develop an efficient method for learning and reproduction of complex trajectories for robot programming by demonstration. Encoding of the demonstrated trajectories is performed with hidden Markov model, and generation of a generalized trajectory is achieved by using the concept of key points. Identification of the key points is based on significant changes in position and velocity in the demonstrated trajectories. The resulting sequences of trajectory key points are temporally aligned using the multidimensional dynamic time warping algorithm, and a generalized trajectory is obtained by smoothing spline interpolation of the clustered key points. The principal advantage of our proposed approach is utilization of the trajectory key points from all demonstrations for generation of a generalized trajectory. In addition, variability of the key points' clusters across the demonstrated set is employed for assigning weighting coefficients, resulting in a generalization procedure which accounts for the relevance of reproduction of different parts of the trajectories. The approach is verified experimentally for trajectories with two different levels of complexity. © 2012 IEEE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5b319383-e246-4e65-9912-3491ae7b4f4f ER - TY - JOUR TI - GPU-based visualization and synchronization of 4-D cardiac MR and ultrasound images DO - 10.1109/TITB.2012.2205011 AU - Zhang, Q. AU - Eagleson, R. AU - Peters, T.M. T2 - IEEE Transactions on Information Technology in Biomedicine SN - 1089-7771 VL - 16 IS - 5 SP - 6220253 SP - 878 EP - 890 KW - Cardiac imaging KW - Dynamic textures KW - extended window-level KW - GPU KW - Image compositing KW - Real time visualization KW - Blending KW - Computerized tomography KW - Heart KW - Image registration KW - Magnetic resonance imaging KW - Optical data processing KW - Program processors KW - Synchronization KW - Three dimensional computer graphics KW - Transfer functions KW - Ultrasonics KW - Visualization KW - Three dimensional KW - algorithm KW - article KW - computer graphics KW - computer simulation KW - factual database KW - four dimensional echocardiography KW - human KW - image processing KW - methodology KW - nuclear magnetic resonance imaging KW - Algorithms KW - Computer Graphics KW - Computer Simulation KW - Databases, Factual KW - Echocardiography, Four-Dimensional KW - Humans KW - Image Processing, Computer-Assisted KW - Magnetic Resonance Imaging, Cine AB - In minimally invasive image-guided interventions, different imaging modalities, such as magnetic resonance imaging (MRI), computed tomography (CT), and 3-D ultrasound (US), can provide complementary, multispectral image information. Dynamic image registration is a well-established approach that permits real-time diagnostic information to be enhanced by placing lower-quality real-time images within a high quality anatomical context. For the guidance of cardiac interventions, it would be valuable to register dynamic MRI or CT with intra-operative US. However, in practice, either the high computational cost prohibits such real-time visualization, or else the resulting image quality is not satisfactory for accurate interventional guidance. Modern graphics processing units (GPUs) provide the programmability, parallelism and increased computational precision to address this problem. In this paper, we first outline our research on dynamic 3-D cardiac MR and US image acquisition, real-time dual-modality registration and US tracking. Next, we describe our contributions on image processing and optimization techniques for 4-D (3-D + time) cardiac image rendering, and our GPU-accelerated methodologies for multimodality 4-D medical image visualization and optical blending, along with real-time synchronization of dual-modality dynamic cardiac images. Finally, multiple transfer functions, various image composition schemes, and an extended window-level setting and adjustment approach are proposed and applied to facilitate the dynamic volumetric MR and US cardiac data exploration and enhance the feature of interest of US image that is usually restricted to a narrow voxel intensity range. © 2012 IEEE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e8160fa1-12d3-4344-9bb6-0c4ffe1bb786 ER - TY - JOUR TI - Electrochemical performance of carbon-supported co-phthalocyanine modified with co-added metals (M = Fe, Co, Ni, V) for oxygen reduction reaction DO - 10.1149/2.058209jes AU - Ding, L. AU - Dai, X. AU - Lin, R. AU - Wang, H. AU - Qiao, J. T2 - Journal of the Electrochemical Society SN - 0013-4651 VL - 159 IS - 9 SP - F577 EP - F584 KW - Carbon-supported catalysts KW - Electrocatalytic activity KW - Electrochemical performance KW - Enhanced catalytic activity KW - High-temperature treatment KW - Oxygen reduction reaction KW - Oxygen reduction reaction kinetics KW - Rotating disk electrodes KW - Catalyst activity KW - Cyclic voltammetry KW - Electrolytic reduction KW - Nickel KW - Rate constants KW - Rotating disks KW - Synthesis (chemical) KW - Carbon AB - Carbon-supported CoPc-M (where M = Fe, Co, Ni, V as the second active component) nanoparticle catalysts have been synthesized via a combined solvent-impregnation and milling procedure along with the high-temperature treatment. The effects of metal addition and metal loading on the electrocatalytic activity of carbon-supported CoPc were studied. Both heated and unheated catalysts were characterized by means of cyclic voltammetry (CV) and linear sweep voltammetry (LSV) employing a rotating disk electrode (RDE) in both acid and alkaline solutions to quantitatively obtain the oxygen reduction reaction (ORR) kinetic constants and the reaction mechanisms. The resulting CoPc-Fe/C of 40:60 ratio, heat-treated at 600°C, exhibited promising catalytic performance in terms of the ORR. The optimal loading of Fe was found to be 5 wt% when Fe loading was varied from 1 wt% to 8 wt% nominal. The transferred electron number, n, per oxygen molecule on CoPc-5%Fe/C electrode is in the range of 2.62-2.66 in acid solution and of 3.03-3.54 in alkaline solution compared to pure CoPc/C with the value of n in the range of 2.01-2.14 in acid solution and of 2.7-3.14 in alkaline solution, respectively. XRD, TEM and XPS analysis revealed that dispersion of the particle size of these carbon-supported catalysts is highly improved after modification of 5%Fe, thus the enhanced catalytic activities due to the increase in active centers which might be from the synergistic effect of Co-Nx and Fe-Nx. © 2012 The Electrochemical Society. All right reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6ab1d186-36b1-49f9-8ebf-27804c0a1088 ER - TY - JOUR TI - AlGaN-free laser diodes by plasma-assisted molecular beam epitaxy DO - 10.1143/APEX.5.022104 AU - Skierbiszewski, C. AU - Siekacz, M. AU - Turski, H. AU - Muzioł, G. AU - Sawicka, M. AU - Feduniewicz-Zmuda, A. AU - Cywiński, G. AU - Cheze, C. AU - Grzanka, S. AU - Perlin, P. AU - Wiśniewski, P. AU - Wasilewski, Z.R. AU - Porowski, S. T2 - Applied Physics Express SN - 1882-0778 VL - 5 IS - 2 SP - 22104 KW - Continuous wave lasing KW - Differential gain KW - GaN substrate KW - Laser structures KW - Optical modes KW - Optical output power KW - Plasma-assisted molecular beam epitaxy KW - Room temperature KW - Threading dislocation densities KW - Threshold currents KW - Gallium nitride KW - Molecular beam epitaxy KW - Epitaxial growth AB - Room-temperature continuous wave lasing at 432nm with a threshold current of 7.6 kA/cm2 for nitride-based laser diodes (LDs) grown by plasma-assisted molecular beam epitaxy is reported. The diodes were grown on c-plane GaN substrates with a threading dislocation density of 5 × 107 cm -2. We used a simplified laser structure design with GaN claddings where the optical modes were confined by the thick 120nm In 0:08Ga 0:92N waveguide. Our LDs show a high optical output power of 130mW, a differential gain of 0.5 W/A, and a lifetime of 50 h. © 2012 The Japan Society of Applied Physics. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2e73a629-fc64-498d-a24e-266215d4256e ER - TY - JOUR TI - Physical simulations of seabed scouring by ice: Review and database AU - Barrette, P. AU - Sudom, D. T2 - Proceedings of the International Offshore and Polar Engineering Conference T3 - 22nd International Offshore and Polar Engineering Conference, ISOPE-2012, 17 June 2012 through 22 June 2012, Rhodes SN - 1098-6189 SN - 9781880653944 SP - 381 EP - 388 KW - Empirical relationships KW - General information KW - Keel KW - Knowledge gaps KW - Physical simulation KW - Seabed KW - Simulation KW - Test condition KW - Testing programs KW - Database systems KW - Geologic models KW - Pipe KW - Pipelines KW - Scour KW - Ice AB - This paper summarizes the compilation of information on physical simulations of seabed scouring by ice keels, and the resulting database. Physical simulations are critical for a proper understanding of ice scouring phenomena. A total of 487 scour simulations from twentyeight studies are reported. General information about test facility, soil, keel type, model pipeline, test conditions and results are outlined. The database can be used as a tool to identify knowledge gaps and guide future testing programs, to generate empirical relationships between the parameters involved during this interaction, or to validate numerical models. Copyright © 2012 by the International Society of Offshore and Polar Engineers (ISOPE). DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e872b6f9-03c0-4e48-a11e-fa0be059635c ER - TY - JOUR TI - Deep-depletion Hamamatsu CCDs for the Gemini multi-object spectrograph DO - 10.1117/12.926834 AU - Hardy, T. AU - Hanna, K. AU - Szeto, K. AU - Burley, G. T2 - High Energy, Optical, and Infrared Detectors for Astronomy V T2 - SPIE - International Society for Optical Engineering. Proceedings; 8453 T3 - High Energy, Optical, and Infrared Detectors for Astronomy V, 1 July 2012 through 4 July 2012, Amsterdam SN - 0277-786X SN - 9780819491541 SP - 84531Y KW - Deep-depletion KW - ESD KW - Focal plane assemblies KW - Hamamatsu KW - High-resistivity KW - Multi-object spectrograph KW - Near-infrared wavelength KW - Astrophysics KW - Charge coupled devices KW - Infrared detectors KW - Spectrographs AB - The instrumentation group of the Herzberg Institute of Astrophysics was commissioned by the Gemini Observatory to develop a new focal plane assembly for the Gemini Multi-Object Spectrograph with an array of three deep-depletion Hamamatsu CCDs. The main objective of the upgrade is to improve the sensitivity of the instrument in the red and nearinfrared wavelengths, with the additional benefits of reduced fringing, faster readout, and better performance in the "nod and shuffle" mode. We describe what we learned about these relatively new CCDs, including several problems encountered during testing, and report on the performance of the system. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2109529e-a22e-48f8-9fe1-8ce48099ba0e ER - TY - CHAP TI - Brassica crop species : improving water use efficiency : challenges and opportunities DO - 10.1002/9783527632930.ch50 AU - Palmer, Constantine Don AU - Keller, Wilf AU - Singh, Jas AU - Datla, Raju T2 - Improving Crop Resistance to Abiotic Stress SN - 9783527328406 VL - 2 SP - 1301 EP - 1314 KW - brassica KW - breeding KW - drought tolerance KW - transpiration efficiency KW - water use efficiency KW - yield AB - The Brassica species occupies a large portion of the world's economically important cultivated crops. These include vegetables, oilseeds, condiments, and forages. These crops are grown globally under a wide range of climatic conditions. With current concerns for food and energy security, expanded use of crop products, and environmental stewardship, there is a pressing need to improve yield through greater efficiency of resource utilization. Water availability is the most limiting factor to crop productivity and with the predicted scarcity, due to climate change and increased nonagricultural demand, improving water use efficiency (WUE) in crop production is an imperative. Consequently, increased carbon assimilation per unit of water used by Brassica crops must not only be realized but this carbon must also be efficiently partitioned into the harvested product. Thus, these plants need to be equipped with the genetic capacity to extract more water from the soil under water-limited conditions, fix more carbon, and transpire less water. There is natural genetic variability for WUE and this can be used for screening germplasm to identify better genotypes. Evaporative demand is the driving force for water loss and WUE can be improved by increasing transpiration efficiency (TE), alteration in crop phenology, increased carbon fixation, and increased harvest index (HI) by greater partitioning of assimilates into harvestable product. Modification of root architecture, leaf morphology, and stomata conductance are important targets for developing cultivars with improved WUE. Drought tolerance is closely associated with WUE and factors contributing to maintenance of metabolic function under water-limited conditions contribute to improved WUE. Studies on Arabidopsis have contributed to significant advances in our understanding of WUE and drought tolerance. The use of genetic engineering and genomic tools has allowed for the incorporation of identified genetic factors for improving WUE and drought tolerance traits and will be vital to the development of new Brassica cultivars. The carbon fixation machinery, a vital component in yield, will require adjustments to deal with anticipated water deficits in order to take advantage of increases in atmospheric carbon dioxide as a result of climate change. Manipulation of assimilate partitioning and selection of genotypes with capacity to store water-soluble carbohydrates in stems that can be remobilized to harvestable structures are targets for improving WUE. To maintain high yields of Brassica crops with economic use of water will require substantial increases in our understanding of the biological processes associated with growth under water-limited conditions. The availability of potential gene targets from the present and future discoveries including rapid advances coming from application of genomic technologies may provide a valuable resource base for development of superior WUE Brassica crops in the coming years. DA - 2012/03/30 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 56778153-1af8-4d2b-a2c9-3398edcf1d8c ER - TY - JOUR TI - Crack growth behavior in ATI 718Plus® alloy DO - 10.4028/www.scientific.net/MSF.706-709.2428 AU - McDevitt, E.T. AU - Oppenheimer, S.M. AU - Kearsey, R.M. AU - Tsang, J. T2 - Materials Science Forum T3 - 7th International Conference on Processing and Manufacturing of Advanced Materials, THERMEC'2011, 1 August 2011 through 5 August 2011, Quebec City, QC SN - 0255-5476 SN - 9783037853030 VL - 706-709 SP - 2428 EP - 2433 KW - Alloy 718 KW - ATI 718Plus KW - Cast and wrought KW - Crack growth behavior KW - Creep crack growth KW - Cyclic loading conditions KW - Engine disk KW - Ni-base alloys KW - Ni-base superalloys KW - Temperature range KW - Testing programs KW - Turbine disks KW - Turbine engine KW - Waspaloy KW - Cracks KW - Creep KW - Fatigue crack propagation KW - Fatigue testing KW - Gas turbines KW - Growth (materials) KW - Mechanical properties KW - Software testing KW - Superalloys KW - Testing KW - Turbomachine blades KW - Alloys KW - Crack propagation KW - Nickel KW - Cerium alloys AB - ATI 718Plus® alloy is a new, cast and wrought, Ni-base superalloy with a maximum use temperature approximately 55°C higher than alloy 718. The mechanical properties have been well characterized by turbine engine OEM's and the alloy has been specified for use as static components and blades in gas turbine engines. Broader use of ATI 718Plus alloy in engine disk applications requires detailed understanding of the damage tolerance under creep and cyclic loading conditions. The results of a large testing program to evaluate the crack growth behavior of ATI 718Plus alloy at temperatures between 649°C and 704°C under conditions of fatigue, dwell-fatigue, and creep are presented. Crack growth rates in ATI 718Plus alloy in this temperature range are lower than alloy 718 and comparable to Waspaloy under non-dwell-fatigue conditions, and comparable to alloy 720 in dwell-fatigue tests. © 2012 Trans Tech Publications, Switzerland. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c6dfcdb0-ff9f-4ed2-8ff5-6b38a9a7deae ER - TY - JOUR TI - Theory of optical properties of II-VI semiconductor quantum dots containing a single magnetic ion in a strong magnetic field DO - 10.1103/PhysRevB.85.165415 AU - Trojnar, A.H. AU - Korkusiński, M. AU - Potemski, M. AU - Hawrylak, P. T2 - Physical Review B - Condensed Matter and Materials Physics SN - 1098-0121 VL - 85 IS - 16 SP - 165415 AB - We present a microscopic theory of the magnetic field dependence of the optical properties of II-VI semiconductor quantum dots containing a single magnetic (Mn) impurity. The single-particle electron and heavy-hole states are described exactly by two-dimensional harmonic oscillators in a magnetic field, the Mn ion is treated as a spin of an isoelectronic impurity, and the quantum dot anisotropy is included perturbatively. The electron-hole direct, short-, and long-range exchange electron-hole Coulomb interactions, as well as the short-range spin-spin contact exchange interaction of the electron and the hole with the magnetic impurity is included. The electron-hole-Mn states are expanded in a finite number of configurations controlled by the number of confined electronic quantum dot shells and the full interacting Hamiltonian is diagonalized numerically in this basis. The absorption and emission spectrum is predicted as a function of photon energy, magnetic field, number of confined shells, and anisotropy. It is shown that the magnetic-field-induced enhancement of the exchange interaction of the Mn spin with the exciton is largely canceled by increased electron-hole Coulomb interactions. The predicted weak magnetic field dependence of the spacing of emission lines agrees well with the results of the spin model at low magnetic fields but differs at higher magnetic fields. Correlations in the exciton-Mn complex are predicted to determine absorption spectra. © 2012 American Physical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f585a8b1-cabe-4665-bc89-1715702769b1 ER - TY - JOUR TI - 99 Herculis: Host to a circumbinary polar-ring debris disc DO - 10.1111/j.1365-2966.2012.20448.x AU - Kennedy, G.M. AU - Wyatt, M.C. AU - Sibthorpe, B. AU - Duchêne, G. AU - Kalas, P. AU - Matthews, B. C. AU - Greaves, J.S. AU - Su, K.Y.L. AU - Fitzgerald, M.P. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 421 IS - 3 SP - 2264 EP - 2276 AB - We present resolved Herschel images of a circumbinary debris disc in the 99 Herculis system. The primary is a late F-type star. The binary orbit is well characterized and we conclude that the disc is misaligned with the binary plane. Two different models can explain the observed structure. The first model is a ring of polar orbits that move in a plane perpendicular to the binary pericentre direction. We favour this interpretation because it includes the effect of secular perturbations and the disc can survive for Gyr time-scales. The second model is a misaligned ring. Because there is an ambiguity in the orientation of the ring, which could be reflected in the sky plane, this ring either has near-polar orbits similar to the first model or has a 30° misalignment. The misaligned ring, interpreted as the result of a recent collision, is shown to be implausible from constraints on the collisional and dynamical evolution. Because disc+star systems with separations similar to 99 Herculis should form coplanar, possible formation scenarios involve either a close stellar encounter or binary exchange in the presence of circumstellar and/or circumbinary discs. Discovery and characterization of systems like 99 Herculis will help understand processes that result in planetary system misalignment around both single and multiple stars. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b2ae89a1-bd3b-4920-8de6-e43be7803257 ER - TY - JOUR TI - A deep, wide-field, and panchromatic view of 47 Tuc and the SMC with HST: Observations and data analysis methods DO - 10.1088/0004-6256/143/1/11 AU - Kalirai, J.S. AU - Richer, H.B. AU - Anderson, J. AU - Dotter, A. AU - Fahlman, G.G. AU - Hansen, B.M.S. AU - Hurley, J. AU - King, I.R. AU - Reitzel, D. AU - Rich, R.M. AU - Shara, M.M. AU - Stetson, P.B. AU - Woodley, K.A. T2 - Astronomical Journal SN - 0004-6256 VL - 143 IS - 1 SP - 11 AB - In Hubble Space Telescope (HST) Cycle 17, we imaged the well-known globular star cluster 47 Tucanae for 121 orbits using the Wide Field Channel of the Advanced Camera for Surveys (ACS) and both the UV/visible (UVIS) and IR channels of the newly installed Wide Field Camera 3 (WFC3) instrument (GO-11677, PI: H. Richer). This unique data set was obtained to address many scientific questions that demand a very deep, panchromatic, and panoramic view of the cluster's stellar populations. In total, the program obtained over 0.75Ms of imaging exposure time with the three HST cameras, over a time span of 9 months in 2010. The primary ACS field was imaged in the two broadband filters F606W and F814W, at 13 orientations, for all 121 orbits. The parallel WFC3 imaging provides a panchromatic (0.4-1.7 μm) and contiguous imaging swath over a 250° azimuthal range at impact radii of 6.5-17.9 pc in 47 Tuc. This imaging totals over 60 arcmin2 in area and utilizes the F390W and F606W broadband filters on WFC3/UVIS and the F110W and F160W broadband filters on WFC3/IR. In this paper, we describe the observational design of the new survey and one of the methods used to analyze all of the imaging data. This analysis combines over 700 full-frame images taken with the three HST cameras into a handful of ultra-deep, well-sampled combined images in each of the six filters. We discuss in detail the methods used to calculate accurate transformations that provide optimal alignment of the input images, the methods used to perform sky background offsets in the input stack and the flagging of deviant pixels, and the balance reached between the input-pixel drop size onto an output supersampled pixel grid. Careful photometric, morphological, and astrometric measurements are performed on the stacks using iterative PSF-fitting techniques, and reveal unprecedented color-magnitude diagrams of the cluster extending to >30th magnitude in the optical, 29th magnitude in the UV, and 27th magnitude in the IR. The data set provides a characterization of the complete stellar populations of 47 Tuc, extending from the faintest hydrogen-burning dwarfs through the main-sequence and giant branches down to very cool white dwarf remnants in the cluster. The imaging also provides the deepest probe of the stellar populations of the background Small Magellanic Cloud galaxy, resolving low-mass main-sequence dwarfs with M ≲ 0.2 M ⊙. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0c6fb07e-7b19-454c-9475-9e7aba3dda0f ER - TY - JOUR TI - VLBI for Gravity Probe B. III. A limit on the proper motion of the "core" of the quasar 3C454.3 DO - 10.1088/0067-0049/201/1/3 AU - Bartel, N. AU - Bietenholz, M.F. AU - Lebach, D.E. AU - Lederman, J.I. AU - Petrov, L. AU - Ransom, R.R. AU - Ratner, M.I. AU - Shapiro, I.I. T2 - Astrophysical Journal, Supplement Series SN - 0067-0049 VL - 201 IS - 1 SP - 3 AB - We made very long baseline interferometry observations at 8.4GHz between 1997 and 2005 to estimate the coordinates of the "core" component of the superluminal quasar, 3C454.3, the ultimate reference point in the distant universe for the NASA/Stanford Gyroscope Relativity Mission, Gravity Probe B (GP-B). These coordinates are determined relative to those of the brightness peaks of two other compact extragalactic sources, B2250+194 and B2252+172, nearby on the sky, and within a celestial reference frame (CRF), defined by a large suite of compact extragalactic radio sources, and nearly identical to the International Celestial Reference Frame 2 (ICRF2). We find that B2250+194 and B2252+172 are stationary relative to each other, and also in the CRF, to within 1σ upper limits of 15 and 30 μasyr -1 in α and δ, respectively. The core of 3C454.3 appears to jitter in its position along the jet direction over 0.2mas, likely due to activity close to the putative supermassive black hole nearby, but on average is stationary in the CRF within 1σ upper limits on its proper motion of 39 μasyr -1 (1.0c) and 30 μasyr -1 (0.8c) in α and δ, respectively, for the period 2002-2005. Our corresponding limit over the longer interval, 1998-2005, of more importance to GP-B, is 46 and 56 μasyr -1 in α and δ, respectively. Some of 3C454.3's jet components show significantly superluminal motion with speeds of up to 200 μasyr -1 or 5c in the CRF. The core of 3C454.3 thus provides for GP-B a sufficiently stable reference in the distant universe. © 2012. The American Astronomical Society. All rights reserved.. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a48d5989-8210-40a2-9356-78ce72cc920f ER - TY - JOUR TI - Lipid-sensing high-throughput ApoA-I assays DO - 10.1177/1087057112451923 AU - Niedziela-Majka, A. AU - Lad, L. AU - Chisholm, J.W. AU - Lagpacan, L. AU - Schwartz, K. AU - Hung, M. AU - Jin, D. AU - Fung, W. AU - Brendza, K.M. AU - Liu, X. AU - Pagratis, N. AU - Sakowicz, R. T2 - Journal of Biomolecular Screening SN - 1087-0571 VL - 17 IS - 8 SP - 1050 EP - 1061 KW - ABC transporter A1 KW - apolipoprotein A1 KW - biotin KW - high density lipoprotein cholesterol KW - lipid KW - streptavidin KW - terbium KW - amino terminal sequence KW - artery wall KW - article KW - atherosclerosis KW - biotinylation KW - cholesterol metabolism KW - cholesterol transport KW - controlled study KW - fluorescence resonance energy transfer KW - foam cell KW - high throughput screening KW - human KW - human cell KW - lipid analysis KW - phospholipid transfer KW - priority journal KW - protein determination KW - radioactivity KW - risk assessment KW - Apolipoprotein A-I KW - Atherosclerosis KW - ATP-Binding Cassette Transporters KW - Biotin KW - Cells, Cultured KW - Cholesterol KW - Fluorescence Resonance Energy Transfer KW - Fluorescent Dyes KW - High-Throughput Screening Assays KW - Humans KW - Lipid Metabolism KW - Lipids KW - Lipoproteins, HDL KW - Macrophages KW - Streptavidin AB - Apolipoprotein A-I (ApoA-I), a primary protein component of high-density lipoprotein (HDL), plays an important role in cholesterol metabolism mediating the formation of HDL and the efflux of cellular cholesterol from macrophage foam cells in arterial walls. Lipidation of ApoA-I is mediated by adenosine triphosphate (ATP) binding cassette A1 (ABCA1). Insufficient ABCA1 activity may lead to increased risk of atherosclerosis due to reduced HDL formation and cholesterol efflux. The standard radioactive assay for measuring cholesterol transport to ApoA-I has low throughput and poor dynamic range, and it fails to measure phospholipid transfer. We describe the development of two sensitive, nonradioactive high-throughput assays that report on the lipidation of ApoA-I: a homogeneous assay based on time-resolved fluorescence resonance energy transfer (TR-FRET) and a discontinuous assay that uses the label-free Epic platform. The TR-FRET assay employs HiLyte Fluor 647-labeled ApoA-I with N-terminal biotin bound to streptavidin-terbium. When fluorescent ApoA-I was incorporated into HDL, TR-FRET decreased proportionally to the increase in the ratio of lipids to ApoA-I, demonstrating that the assay was sensitive to the amount of lipid bound to ApoA-I. In the Epic assay, biotinylated ApoA-I was captured on a streptavidin-coated biosensor. Measured resonant wavelength shift was proportional to the amount of lipids associated with ApoA-I, indicating that the assay senses ApoA-I lipidation. © 2012 Society for Laboratory Automation and Screening. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0c65e909-444a-4fc9-8e51-edaf0d8fc109 ER - TY - JOUR TI - Motor protein Myo5p is required to maintain the regulatory circuit controlling WOR1 expression in Candida albicans DO - 10.1128/EC.00021-12 AU - Kachurina, N. AU - Turcotte, B. AU - Whiteway, M. T2 - Eukaryotic Cell SN - 1535-9778 VL - 11 IS - 5 SP - 626 EP - 637 KW - fungal protein KW - green fluorescent protein KW - myosin I KW - transcription factor KW - allele KW - article KW - Candida albicans KW - culture medium KW - fungal gene KW - gene expression regulation KW - gene inactivation KW - gene regulatory network KW - genetic transcription KW - genetics KW - metabolism KW - phenotype KW - physiology KW - promoter region KW - real time polymerase chain reaction KW - regulator gene KW - Alleles KW - Candida albicans KW - Culture Media KW - Fungal Proteins KW - Gene Expression Regulation, Fungal KW - Gene Knockout Techniques KW - Gene Regulatory Networks KW - Genes, Mating Type, Fungal KW - Genes, Switch KW - Green Fluorescent Proteins KW - Myosin Type I KW - Phenotype KW - Promoter Regions, Genetic KW - Real-Time Polymerase Chain Reaction KW - Transcription Factors KW - Transcription, Genetic KW - Candida albicans AB - The Candida albicans MYO5 gene encodes myosin I, a protein required for the formation of germ tubes and true hyphae. Because the polarized growth of opaque-phase cells in response to pheromone results in mating projections that can resemble germ tubes, we examined the role of Myo5p in this process. We localized green fluorescent protein (GFP)-tagged Myo5p in opaquephase cells of C. albicans during both bud and shmoo formation. In vegetatively growing opaque cells, Myo5p is found at sites of bud emergence and bud growth, while in pheromone-stimulated cells, Myo5p localizes at the growing tips of shmoos. Intriguingly, cells homozygous for MTLa in which the MYO5 gene was deleted failed to switch efficiently from the white phase to the opaque phase, although ectopic expression of WOR1 from the MET3 promoter can convert myo5 mutants into mating-competent opaque cells. However, when WOR1 expression was shut off, the myo5-defective cells rapidly lost both their opaque phenotype and mating competence, suggesting that Myo5p is involved in the maintenance of the opaque state. When MYO5 is expressed conditionally in opaque cells, the opaque phenotype, as well as the mating ability of the cells, becomes unstable under repressive conditions, and quantitative real-time PCR demonstrated that the shutoff of MYO5 expression correlates with a dramatic reduction in WOR1 expression. It appears that while myosin I is not directly required for mating in C. albicans, it is involved in WOR1 expression and the white-opaque transition and thus is indirectly implicated in mating. © 2012, American Society for Microbiology. All Rights Reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 26c4ecb3-59ad-4ebd-a1d9-7280ed2016db ER - TY - JOUR TI - The Next Generation Virgo Cluster Survey (NGVS). I. Introduction to the survey DO - 10.1088/0067-0049/200/1/4 AU - Ferrarese, L. AU - Côté, P. AU - Cuillandre, J.-C. AU - Gwyn, S.D.J. AU - Peng, E.W. AU - MacArthur, L.A. AU - Duc, P.-A. AU - Boselli, A. AU - Mei, S. AU - Erben, T. AU - McConnachie, A.W. AU - Durrell, P.R. AU - Christopher Mihos, J. AU - Jordán, A. AU - Lançon, A. AU - Puzia, T.H. AU - Emsellem, E. AU - Balogh, M.L. AU - Blakeslee, J.P. AU - Van Waerbeke, L. AU - Gavazzi, R. AU - Vollmer, B. AU - Kavelaars, J.J. AU - Woods, D. AU - Ball, N.M. AU - Boissier, S. AU - Courteau, S. AU - Ferriere, E. AU - Gavazzi, G. AU - Hildebrandt, H. AU - Hudelot, P. AU - Huertas-Company, M. AU - Liu, C. AU - McLaughlin, D. AU - Mellier, Y. AU - Milkeraitis, M. AU - Schade, D. AU - Balkowski, C. AU - Bournaud, F. AU - Carlberg, R.G. AU - Chapman, S.C. AU - Hoekstra, H. AU - Peng, C. AU - Sawicki, M. AU - Simard, L. AU - Taylor, J.E. AU - Brent Tully, R. AU - Van Driel, W. AU - Wilson, C.D. AU - Burdullis, T. AU - Mahoney, B. AU - Manset, N. T2 - Astrophysical Journal, Supplement Series SN - 0067-0049 VL - 200 IS - 1 SP - 4 AB - The Next Generation Virgo Cluster Survey (NGVS) is a program that uses the 1 deg 2 MegaCam instrument on the Canada-France-Hawaii Telescope to carry out a comprehensive optical imaging survey of the Virgo cluster, from its core to its virial radius - covering a total area of 104 deg 2 - in the u*griz bandpasses. Thanks to a dedicated data acquisition strategy and processing pipeline, the NGVS reaches a point-source depth of g 25.9 mag (10σ) and a surface brightness limit of μ g 29 mag arcsec -2 (2σ above the mean sky level), thus superseding all previous optical studies of this benchmark galaxy cluster. In this paper, we give an overview of the technical aspects of the survey, such as areal coverage, field placement, choice of filters, limiting magnitudes, observing strategies, data processing and calibration pipelines, survey timeline, and data products. We also describe the primary scientific topics of the NGVS, which include: the galaxy luminosity and mass functions; the color-magnitude relation; galaxy scaling relations; compact stellar systems; galactic nuclei; the extragalactic distance scale; the large-scale environment of the cluster and its relationship to the Local Supercluster; diffuse light and the intracluster medium; galaxy interactions and evolutionary processes; and extragalactic star clusters. In addition, we describe a number of ancillary programs dealing with "foreground" and "background" science topics, including the study of high-inclination trans-Neptunian objects; the structure of the Galactic halo in the direction of the Virgo Overdensity and Sagittarius Stream; the measurement of cosmic shear, galaxy-galaxy, and cluster lensing; and the identification of distant galaxy clusters, and strong-lensing events. © 2012. The American Astronomical Society. All rights reserved.. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7c99735e-6c45-4ea3-b751-6cb8a6801f4f ER - TY - JOUR TI - Fuel property effects on PCCI combustion in a heavy-duty diesel engine DO - 10.1115/1.4005213 AU - Dumitrescu, C.E. AU - Stuart Neill, W. AU - Guo, H. AU - Hosseini, V. AU - Chippior, W.L. T2 - Journal of Engineering for Gas Turbines and Power SN - 0742-4795 VL - 134 IS - 5 SP - 52801 KW - Absolute values KW - Air/fuel ratio KW - Brake mean effective pressures KW - Brake specific fuel consumption KW - CO emissions KW - Combustion duration KW - Combustion engines KW - Combustion phasing KW - Common rail KW - Distillation temperature KW - experimental KW - Experimental studies KW - Fuel injection systems KW - Fuel matrix KW - Fuel properties KW - Heavy-duty diesel engine KW - Ignition delays KW - Injection timing KW - matrix KW - PCCI combustion KW - Premixed charge compression ignition KW - Premixing KW - Rail pressures KW - Soot emissions KW - Top dead center KW - Antiknock rating KW - Brakes KW - Design KW - Diesel engines KW - Diesel fuels KW - Distillation KW - Fuel injection KW - Ignition KW - Internal combustion engines KW - Soot KW - Fuels AB - An experimental study was performed to investigate fuel property effects on premixed charge compression ignition (PCCI) combustion in a heavy-duty diesel engine. A matrix of research diesel fuels designed by the Coordinating Research Council, referred to as the Fuels for Advanced Combustion Engines (FACE), was used. The fuel matrix design covers a wide range of cetane numbers (30 to 55), 90% distillation temperatures (270 to 340° C) and aromatics content (20 to 45%). The fuels were tested in a single-cylinder Caterpillar diesel engine equipped with a common-rail fuel injection system. The engine was operated at 900 rpm, a relative air/fuel ratio of 1.2 and 60% exhaust gas recirculation (EGR) for all fuels. The study was limited to a single fuel injection event starting between -30° and 0° CA after top dead center (aTDC) with a rail pressure of 150 MPa. The brake mean effective pressure (BMEP) ranged from 2.6 to 3.1 bar depending on the fuel and its injection timing. The experimental results show that cetane number was the most important fuel property affecting PCCI combustion behavior. The low cetane number fuels had better brake specific fuel consumption (BSFC) due to more optimized combustion phasing and shorter combustion duration. They also had a longer ignition delay period available for premixing, which led to near-zero soot emissions. The two fuels with high cetane number and high 90 distillation temperature produced significant soot emissions. The two fuels with high cetane number and high aromatics produced the highest brake specific NO x emissions, although the absolute values were below 0.1 g/kW-h. Brake specific HC and CO emissions were primarily a function of the combustion phasing, but the low cetane number fuels had slightly higher HC and lower CO emissions than the high cetane number fuels. © 2012 American Society of Mechanical Engineers. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6c741167-82be-4b21-ae00-8375faf7868b ER - TY - JOUR TI - Dyson norms in XUV and strong-field ionization of polyatomics: Cytosine and uracil DO - 10.1103/PhysRevA.86.053406 AU - Spanner, M. AU - Patchkovskii, S. AU - Zhou, C. AU - Matsika, S. AU - Kotur, M. AU - Weinacht, T.C. T2 - Physical Review A - Atomic, Molecular, and Optical Physics SN - 1050-2947 VL - 86 IS - 5 SP - 53406 KW - Ammosov-Delone-Krainov KW - Continuum structures KW - Dyson orbital KW - Extreme ultraviolets KW - Ionic state KW - Matrix elements KW - Multi-electron KW - Polyatomics KW - Strong field ionization KW - Time-dependent KW - Tunneling ionization KW - Valence ionization KW - Aromatic compounds KW - Estimation KW - Interlocking signals KW - Positive ions KW - Photoionization AB - The extreme-ultraviolet (XUV) and strong-field valence ionization of cytosine and uracil is considered. We examine some simple estimates of the relative yields of the cation states populated following ionization and compare these to the results of a recently developed ab initio-type numerical model designed to compute strong-field ionization of molecules, the so-called time-dependent resolution in ionic states (TD-RIS) method. In analogy with one-photon XUV ionization, where the photoionization matrix elements can be related to the Dyson orbitals, we construct estimates for the yield of strong-field ionization (SFI) to different cation states based on the Dyson orbital norms and the Keldysh tunneling ionization rate. In the case of XUV ionization, the Dyson norms are shown to be good predictors of the relative cation yields when compared with the TD-RIS yields. The Dyson- and Keldysh-based models underestimate the yield to excited cation states in the case of SFI. The increased yield to the excited cation states in the TD-RIS results is attributed to the inclusion of multielectron effects and continuum structure not present in the simple models. The molecular Ammosov-Delone-Krainov (MO-ADK) method of calculating SFI is also considered. This later method is seen to agree more closely with the Dyson- and Keldysh-based estimates as it also fails to capture the multielectron effects and continuum structure included in the TD-RIS approach. ©2012 American Physical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0382aa20-288c-410e-b8e4-b6414a830f0f ER - TY - JOUR TI - The structure of the extracellular teichoic acids from the allergy-protective bacterium Lactococcus lactis G121 DO - 10.1515/hsz-2012-0142 AU - Fischer, K. AU - Vinogradov, E. AU - Lindner, B. AU - Heine, H. AU - Holst, O. T2 - Biological Chemistry SN - 1431-6730 VL - 393 IS - 8 SP - 749 EP - 755 KW - antiallergic agent KW - extracellular teichoic acid KW - sodium chloride KW - teichoic acid KW - unclassified drug KW - allergic asthma KW - article KW - chemical structure KW - controlled study KW - electrospray mass spectrometry KW - extraction KW - gel permeation chromatography KW - ion cyclotron resonance mass spectrometry KW - Lactococcus lactis KW - nonhuman KW - priority journal KW - proton nuclear magnetic resonance KW - Animals KW - Carbohydrate Sequence KW - Hypersensitivity KW - Lactococcus lactis KW - Mice KW - Molecular Sequence Data KW - Nuclear Magnetic Resonance, Biomolecular KW - Spectrometry, Mass, Electrospray Ionization KW - Teichoic Acids AB - The Gram-positive bacterium Lactococcus lactis G121 is a farm isolate that protects mice from ovalbumin-induced asthma. To understand the molecular mechanisms of such allergy-protective properties, the isolation and characterization of cell envelope constituents is crucial. Here, structural analyses of the extracellular teichoic acid (EC TA) from L. lactis G121 are presented. Extraction with 0.9 % saline afforded a crude TA fraction. Consecutive size exclusion chromatography on Biogel P60 and P10 matrix was performed to purify the sample. Chemical component analyses, high-resolution electrospray ionization Fourier-transformed ion cyclotron mass spectrometry, and nuclear magnetic resonance spectroscopy were conducted for structural elucidation. The EC TA was a poly(glycosylglycerol phosphate) molecule with a repeating unit of -6)-[β- d-Glcp -(1→3)-][α- d-Glcp NAc-(1→4)-]α- d-Galp NAc-(1→3)-β-d-Glcp NAc-(1→2)-glycerol-(1- P -). Copyright © by Walter de Gruyter • Berlin • Boston. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1463305d-cd2d-4694-97d6-5be431f56e7f ER - TY - JOUR TI - Development of a tissue-mimicking neck model for medical education DO - 10.2310/7070.2011.110274 AU - Xu, J.J. AU - Fung, K. AU - Glicksman, J.D. AU - Brandt, M.G. AU - Campbell, G. T2 - Journal of Otolaryngology - Head and Neck Surgery SN - 1916-0216 VL - 41 IS - 2 SP - 145 EP - 151 KW - polyvinyl alcohol KW - article KW - cryogel KW - elasticity KW - geometry KW - image reconstruction KW - lymph node KW - medical education KW - neck KW - neck tumor KW - nuclear magnetic resonance imaging KW - palpation KW - priority journal KW - simulation KW - stereolithography KW - Education, Medical KW - Head and Neck Neoplasms KW - Humans KW - Imaging, Three-Dimensional KW - Lymph Nodes KW - Magnetic Resonance Imaging KW - Models, Anatomic KW - Neck KW - Palpation KW - Reproducibility of Results KW - Tomography, X-Ray Computed AB - Background: The ability to palpate neck masses and lymph nodes and appreciate qualities such as size, location, and consistency is critical for patient care and an important clinical skill for all physicians. Medical students currently learn neck palpation by practicing on healthy, standardized patients; however, studies of similar procedures have shown that educational models with simulated pathology help improve technique and confidence. Objective: Our goal was to create a tissue-mimicking neck model with palpable masses. Methods: Iterative design and development of a high-fidelity neck model using polyvinyl alcohol-cryogel (PVA-C), a nontoxic and biocompatible polymer that exhibits favourable tissue-mimicking elastic properties. Model geometries were digitally reconstructed from high-resolution cadaveric magnetic resonance imaging sections to create physical moulds through stereolithography. PVA-C was formulated to mimic the characteristics of human tissue. Results: A life-like neckmodelwas built and consists of these components: muscle, larynx, spine, soft tissue, pathologic nodes, and skin. Discussion: A final neck model prototype has been completed and will be evaluated by otolaryngology consultants and residents for face and construct validity and assessed in a randomized, controlled trial to evaluate how it impacts students' ability to detect neck masses. © 2012 The Canadian Society of Otolaryngology-Head & Neck Surgery. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0affbcb9-23a4-4bbd-b710-b75d8ff69ba2 ER - TY - JOUR TI - Athermal silicon waveguides with bridged subwavelength gratings for TE and TM polarizations DO - 10.1364/OE.20.018356 AU - Ibrahim, Marc AU - Schmid, Jens H. AU - Aleali, Alireza AU - Cheben, Pavel AU - Lapointe, Jean AU - Janz, Siegfried AU - Bock, Przemek J. AU - Densmore, Adam AU - Lamontagne, Boris AU - Ma, Rubin AU - Xu, Dan-Xia AU - Ye, Winnie N. T2 - Optics Express SN - 1094-4087 VL - 20 IS - 16 SP - 18356 EP - 18361 KW - Cladding material KW - Duty cycles KW - Grating pitch KW - Silicon waveguide KW - SU-8 polymer KW - Sub-wave length grating KW - Thermooptic coefficients KW - TM polarization KW - Cladding (coating) KW - Polarization KW - Waveguides AB - In this paper, athermal silicon waveguides using bridged subwavelength grating (BSWG) structures are proposed and investigated. The realization of temperature-independent BSWG waveguides for both polarizations is demonstrated numerically and experimentally. SU-8 polymer is used as the cladding material to compensate for the positive thermo-optic (TO) coefficient (dn/dT) of silicon. We investigate the dependence of the effective TO coefficient of BSWG waveguides on both the bridge width and grating duty cycle. The BSWG waveguides have a width of 490 nm, a height of 260 nm, and a grating pitch of 250 nm. Athermal behavior is achieved for both the transverse-magnetic (TM) and the transverse-electric (TE) polarized light for a variety of bridge width and duty cycle combinations. Furthermore, the BSWGs can be designed to be athermal for both TE and TM polarization simultaneously. © 2012 Optical Society of America. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2bae0364-f8fe-4199-8766-0842e0c27a30 ER - TY - JOUR TI - Temperature-independent silicon waveguides comprising bridged subwavelength gratings DO - 10.1117/12.2001480 AU - Ibrahim, M. AU - Aleali, A. AU - Schmid, J.H. AU - Cheben, P. AU - Lapointe, J. AU - Janz, S. AU - Bock, P.J. AU - Densmore, A. AU - Lamontagne, B. AU - Ma, R. AU - Xu, D.-X. AU - Ye, W.N. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Photonics North 2012, 6 June 2012 through 8 June 2012, Montreal, QC SN - 0277-786X SN - 9780819490902 VL - 8412 SP - 84120Z KW - Athermal KW - Grating duty cycle KW - Silicon photonics KW - Sub-wave length grating KW - Thermo-optic coefficients KW - Electric losses KW - Photonics KW - Silicon KW - Waveguides AB - Athermal operation of silicon waveguides for the TM and TE mode is achieved using the bridged subwavelength grating (BSWG) waveguide geometry. For the TM mode the experimental results show that the temperature-induced wavelength shift (dλ/dT) is an order of magnitude smaller for the BSWG waveguides with grating duty cycle, waveguide and bridge widths of 42%, 490 nm and 220 nm, respectively, as compared to standard photonics wires (PW). For the TE mode similar results are achieved by using the bridge width of 200 nm and similar duty cycle and waveguide width. A temperature-induced shift of only -2.5 pm/°C is reported for the TM polarized light. Propagation losses of BSWG waveguides for both polarizations were measured to be about 8 dB/cm, comparable to that of PWs. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ba120e3d-7fe7-49ed-b59e-5af7f14248cf ER - TY - JOUR TI - Silicon and silicon oxide surface modification using thiamine-catalyzed benzoin condensations DO - 10.1139/v11-157 AU - Hoop, K.A. AU - Kennedy, D.C. AU - Mishki, T. AU - Lopinski, G.P. AU - Pezacki, J.P. T2 - Canadian Journal of Chemistry SN - 0008-4042 VL - 90 IS - 3 SP - 262 EP - 270 KW - Benzoin condensation KW - Catalysis in water KW - Functionalized KW - N-heterocyclic carbenes KW - Silicon oxide surfaces KW - Surface functionalization KW - Umpolung KW - Aldehydes KW - Catalysis KW - Condensation KW - Functional groups KW - Silicon KW - Silicon compounds KW - X ray photoelectron spectroscopy KW - Silicon oxides AB - The benzoin condensation that involves the umpolung coupling of two aldehyde groups has been applied to the formation of functionalized silicon and silicon oxide surfaces using thiamine and other N-heterocyclic carbene (NHC) catalysis in water. This bioorthogonal conjugation of an aldehyde to a modified silicon or silicon oxide surface has been monitored and characterized using X-ray photoelectron spectroscopy and IR spectroscopy. NHC catalysis was found to be efficient in water mediating full conversion of the aldehyde functionalized silicon oxide surfaces at the interface. © 2012 Published by NRC Research Press. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 631af60e-3a6e-4831-9905-2e0a46f11cdb ER - TY - JOUR TI - Persistence and eventual demise of oxygen molecules at terapascal pressures DO - 10.1103/PhysRevLett.108.045503 AU - Sun, J. AU - Martinez-Canales, M. AU - Klug, D.D. AU - Pickard, C.J. AU - Needs, R.J. T2 - Physical Review Letters SN - 0031-9007 VL - 108 IS - 4 SP - 45503 KW - Chainlike structure KW - Complex evolutions KW - High pressure KW - Nearest neighbors KW - Oxygen molecule KW - Polymeric structures KW - Solid oxygen KW - Superconducting properties KW - Density functional theory KW - Electronic properties KW - Molecular oxygen AB - Computational searches for structures of solid oxygen under high pressures in the multi-TPa range are carried out using density-functional-theory methods. We find that molecular oxygen persists to about 1.9 TPa at which it transforms into a semiconducting square-spiral-like polymeric structure (I4 1/acd) with a band gap of ∼3.0eV. Solid oxygen forms a metallic zigzag chainlike structure (Cmcm) at about 3.0 TPa, but the chains in each layer gradually merge as the pressure is increased and a structure of Fmmm symmetry forms at about 9.3 TPa in which each atom has four nearest neighbors. The superconducting properties of molecular oxygen do not vary much with compression, although the structure becomes more symmetric. The electronic properties of oxygen have a complex evolution with pressure, swapping between insulating, semiconducting, and metallic. © 2012 American Physical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : dd84ca59-a04e-41e5-9b4b-453aea245872 ER - TY - JOUR TI - Solid state spectroelectrochemistry of redox reactions in polypyrrole/oxide molecular heterojunctions DO - 10.1021/ac2032047 AU - Bonifas, A.P. AU - McCreery, R.L. T2 - Analytical Chemistry SN - 0003-2700 VL - 84 IS - 5 SP - 2459 EP - 2465 KW - Absorbance change KW - Applied bias KW - Carbon electrode KW - Imine formation KW - In-situ KW - Ion Mobility KW - Negative bias KW - Oxidation state KW - Oxide junction KW - Polaron formation KW - Polypyrrole (PPy) KW - Positive bias KW - Resistance switching KW - Solid-state carbon KW - Spectral change KW - Surrounding environment KW - Acetonitrile KW - Electric resistance KW - Heterojunctions KW - Nitrogen compounds KW - Oxidation KW - Platinum KW - Polypyrroles KW - Redox reactions KW - Solid state devices KW - Spectroelectrochemistry KW - Ultraviolet spectroscopy KW - Polarons AB - To understand the mechanism of bias-induced resistance switching observed in polypyrrole (PPy) based solid state junctions, in situ UV-vis absorption spectroscopy was employed to monitor oxidation states within PPy layers in solution and in PPy/metal oxide junctions. For PPy layers in acetonitrile, oxidation led primarily to cationic polaron formation, while oxidation in 0.1 M NaOH in H 2O resulted in imine formation, caused by deprotonation of polarons. On the basis of these results in solution, spectroelectrochemistry was used to monitor bias-induced formation of polarons and imines in PPy layers incorporated into solid state carbon/PPy/Al 2O 3/Pt junctions. A positive bias on the carbon electrode caused PPy oxidation, with the formation of polaron and imine species strongly dependent on the surrounding environment. The spectral changes associated with polarons or imines were stable for at least several hours after the applied bias, while a negative bias reversed the absorbance changes back to the initial PPy spectrum. These results indicate that PPy can be oxidized in nominally solid state devices, and the formation of stable polarons is dependent on the tendency for deprotonation of the polaron to the imine. Since PPy conductivity depends strongly on the polaron concentration, monitoring its concentration is critical to determining resistance switching mechanisms. Furthermore, the importance of ion mobility and OH - generation through H 2O reduction at the Pt contact are discussed. © 2012 American Chemical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 25df34b7-0d08-437d-8315-a50684bcf0a5 ER - TY - JOUR TI - A measurement system with contour tracking for repair of components DO - 10.1504/IJMR.2012.045242 AU - Li, Y. AU - Xue, L. T2 - International Journal of Manufacturing Research SN - 1750-0591 VL - 7 IS - 1 SP - 26 EP - 41 KW - Contour tracking KW - Displacement sensor KW - High resolution sensors KW - Laser displacement sensors KW - Measurement system KW - Measuring accuracy KW - Motion system KW - Range sensors KW - Surface contour KW - Target surface KW - Contour measurement KW - Laser cladding KW - Measurements KW - Repair KW - Sensors KW - Displacement measurement AB - The repair of worn-out components requires the extraction of their actual geometry. To acquire the surface contour, a laser displacement sensor and a CNC motion system are typically used. One of the factors that affect the measuring accuracy is the sensor's resolution. A high resolution sensor usually has a short measuring range. Therefore, a contour with a large peak-to-valley height cannot usually be measured using a short range sensor. In this research, a measurement system of tracking target surface was developed. The proposed measurement system has been used for repair of worn-out components using laser cladding. Copyright © 2012 Inderscience Enterprises Ltd. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9cc28450-2e39-4346-86ea-f506da63978b ER - TY - JOUR TI - Insights into semiconductor nanowire conductivity using electrodeposition DO - 10.1088/0268-1242/27/10/105020 AU - Liu, C. AU - Salehzadeh, O. AU - Poole, P.J. AU - Watkins, S.P. AU - Kavanagh, K.L. T2 - Semiconductor Science and Technology SN - 0268-1242 VL - 27 IS - 10 SP - 105020 KW - Core-shell KW - Depletion layer KW - Electrical contacts KW - GaAs KW - Gold catalysts KW - InAs KW - Metal growth KW - Nucleation and growth KW - P-type GaAs KW - Semiconductor nanowire KW - Catalysts KW - Electrodeposition KW - Gold KW - Indium arsenide KW - Nanowires KW - Semiconducting gallium KW - Gallium arsenide AB - Copper (Cu) and iron (Fe) electrical contacts to gallium arsenide (GaAs) and indium arsenide (InAs) nanowires (NWs) have been fabricated via electrodeposition. For undoped or low carbon-doped (10 17/cm 3), p-type GaAs NWs, Cu or Fe nucleate and grow only on the gold catalyst at the NW tip, avoiding the sidewalls. Metal growth is limited by the Au contact resistance due to thick sidewall depletion layers. For InAs NWs and heavier-doped, core-shell (undoped core-C-doped shell) GaAs NWs, metal nucleation and growth occurs on the sidewalls as well as on the gold catalyst limited now by the ion electrolyte diffusivity. © 2012 IOP Publishing Ltd. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c0cfd275-6136-42e6-8f4a-7d6afd483cbc ER - TY - JOUR TI - Microindentation creep of secondary hydrated cement phases and C-S-H DO - 10.1617/s11527-012-9993-0 AU - Nguyen, D.-T. AU - Alizadeh, R. AU - Beaudoin, J.J. AU - Raki, L. T2 - Materials and Structures/Materiaux et Constructions SN - 1359-5997 SP - 1 EP - 7 AB - Microindentation creep measurements were obtained on compacted specimens of several secondary hydrated cement phases in equilibrium with water vapor at 11%RH. Values of creep modulus, indentation modulus and indentation hardness for calcium hydroxide, ettringite, gypsum and calcium carbonate are reported. The porosity dependence of these parameters was established and the significance of porosity on the time-dependent deformation of these materials was discussed. In addition the microindentation creep behavior of pure C-S-H and C3S paste hydrated 32 years was determined. The discussion focuses on the relative importance of the contribution of the secondary phases in hydrated cement-based materials to creep with respect to the more 'active' C-S-H phase. © 2012 RILEM. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 69188546-7213-43e6-bfba-8f725ea32ef5 ER - TY - JOUR TI - The multielectron ionization dynamics underlying attosecond strong-field spectroscopies DO - 10.1126/science.1212896 AU - Boguslavskiy, A.E. AU - Mikosch, J. AU - Gijsbertsen, A. AU - Spanner, M. AU - Patchkovskii, S. AU - Gador, N. AU - Vrakking, M.J.J. AU - Stolow, A. T2 - Science SN - 0036-8075 VL - 335 IS - 6074 SP - 1336 EP - 1340 KW - hydrocarbon KW - electron KW - hydrocarbon KW - ionization KW - spectroscopy KW - timescale KW - absorption KW - absorption spectroscopy KW - article KW - chemical structure KW - electron KW - geometry KW - ionization KW - laser KW - multielectron ionization dynamics KW - photon KW - priority journal KW - spectroscopy AB - Subcycle strong-field ionization (SFI) underlies many emerging spectroscopic probes of atomic or molecular attosecond electronic dynamics. Extending methods such as attosecond high harmonic generation spectroscopy to complex polyatomic molecules requires an understanding of multielectronic excitations, already hinted at by theoretical modeling of experiments on atoms, diatomics, and triatomics. Here, we present a direct method which, independent of theory, experimentally probes the participation of multiple electronic continua in the SFI dynamics of polyatomic molecules. We use saturated (n-butane) and unsaturated (1,3-butadiene) linear hydrocarbons to show how subcycle SFI of polyatomics can be directly resolved into its distinct electronic-continuum channels by above-threshold ionization photoelectron spectroscopy. Our approach makes use of photoelectron-photofragment coincidences, suiting broad classes of polyatomic molecules. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ac273dda-8290-48f8-a5a0-6deb7e395b38 ER - TY - JOUR TI - Nickel nanoparticles synthesized by a modified polyol method for the purification of histidine-tagged single-domain antibody ToxA5.1 DO - 10.1557/jmr.2012.323 AU - Parisien, A. AU - Al-Zarka, F. AU - Hussack, G. AU - Baranova, E.A. AU - Thibault, J. AU - Qingdao Lan, C. T2 - Journal of Materials Research SN - 0884-2914 VL - 27 IS - 22 SP - 2884 EP - 2890 KW - Adsorption cycle KW - Average diameter KW - Binding capacities KW - Ferromagnetic behaviors KW - magnetic KW - Magnetic adsorbents KW - Magnetic characterization KW - Magnetization-saturation KW - Modified polyol method KW - Nickel nanoparticles KW - Nucleating agents KW - Palladium chloride KW - Polyvinyl pyrrolidone KW - Protective agents KW - Protein purification KW - Single domains KW - Adsorbents KW - Adsorption KW - Alcohols KW - Amino acids KW - Antibodies KW - Chlorine compounds KW - Ethylene glycol KW - Magnetic domains KW - Nanomagnetics KW - Nanoparticles KW - Nickel KW - Nickel compounds KW - Palladium KW - Purification KW - Recombinant proteins KW - Saturation magnetization KW - X ray diffraction KW - Biosynthesis AB - Nickel nanoparticles (NNPs) synthesized by a modified polyol method using ethylene glycol as a reducing agent, palladium chloride as a nucleating agent, and polyvinylpyrrolidone (PVP) as a protective agent were investigated as a potential magnetic adsorbent for the purification of hexahistidine-tagged (His6-tagged) recombinant proteins. The synthesis resulted in nanoparticles having an average diameter of 6828 nm. The x-ray diffraction pattern confirmed the presence of nickel metal, as well as the presence of unreacted nickel (II) hydroxide Ni(OH)2. Magnetic characterization showed that a magnetization saturation of 39.3 electromagnetic unit (emu)/g at 20,000 Oersted (Oe) was reached rapidly and that the material exhibited ferromagnetic behavior. Protein purification results showed that the synthesized NNPs were highly selective for binding to a His6-tagged recombinant protein single-domain antibody ToxA5.1. In addition, NNPs were used for four adsorption cycles without significant binding capacity losses. These particles have shown great potential such as being easily synthesized, cost-effective, and highly selective magnetic adsorbents for the purification of His6-tagged recombinant proteins. © Copyright © Materials Research Society 2012. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b1c3d0e3-befa-4853-86c1-742479160b0e ER - TY - JOUR TI - Debris discs at centimetre wavelengths: Planetesimal populations in young extrasolar Kuiper belts DO - 10.1111/j.1745-3933.2012.01259.x AU - Greaves, J.S. AU - Hales, A.S. AU - Mason, B.S. AU - Matthews, B.C. T2 - Monthly Notices of the Royal Astronomical Society: Letters SN - 1745-3933 VL - 423 IS - 1 SP - L70 EP - L74 AB - Two luminous debris discs around 100 Myr old have been searched for 1 cm dust emission, to a depth three times greater than in any such previous study. Very low limits were set towards both HD 377 and HD 104860 (noise levels of 12-14 μJy), extending the spectral range from 70 μm to 3mm where cool dust has previously been sought. The almost-identical fluxes of the two systems were merged into an average spectral energy distribution, which was then fitted using a distribution of grain sizes. The canonical infinite collisional cascade, with numbers of particles n(D)∝D -3.5 for diameter D, overpredicts the 1-cm flux, which should have been detected at over 3σ for the merged system. Preferred solutions have truncated grain populations with largest particles around 1.5-4mm in diameter, and slightly flatter distributions, up to n(D)∝D -3.1. The lack of cm-sized and larger particles is reminiscent of the similar deficit inferred around comets from spacecraft encounters. Such departures from simple power-law distributions of particles have been predicted in recent models where some size regimes are more readily broken up than others. A deficit of cm-scale particles can explain the fits we obtain, and reduces the total masses inferred for the comet belts of these stars. © 2012 The Authors. Monthly Notices of the Royal Astronomical Society. © 2012 RAS. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ed05b845-0f81-4186-a829-69eb29a21aa7 ER - TY - JOUR TI - Single-walled carbon nanotube-modified epoxy thin films for continuous crack monitoring of metallic structures DO - 10.1177/1475921712449509 AU - Ashrafi, B. AU - Johnson, L. AU - Martinez-Rubi, Y. AU - Martinez, M. AU - Mrad, N. T2 - Structural Health Monitoring SN - 1475-9217 VL - 11 IS - 5 SP - 589 EP - 601 KW - Accurate measurement KW - Catastrophic failures KW - Continuous monitoring KW - Crack evolution KW - Crack length KW - Crack monitoring KW - Crack sensors KW - Crack sizes KW - Crack surfaces KW - Current change KW - Electrical discharge machining KW - Epoxy nanocomposites KW - Fatigue cycles KW - Gauge factors KW - Growth monitoring KW - Host structure KW - Linear correlation KW - Maximum load KW - Measured currents KW - Metallic hosts KW - Metallic structures KW - Nanocomposite thin films KW - Single-walled carbon KW - Small load KW - Stable modes KW - Strain sensing KW - Visual inspection KW - Aluminum KW - Carbon nanotubes KW - Crack detection KW - Epoxy resins KW - Fatigue testing KW - Mechanical properties KW - Nanocomposite films KW - Nanocomposites KW - Sensors KW - Single-walled carbon nanotubes (SWCN) KW - Structural health monitoring KW - Cracks AB - Cracks are one of the primary forms of damage that can lead to the catastrophic failure of metallic structures. This study focuses on the application of epoxy nanocomposite thin film sensors for continuous monitoring of crack evolution in metallic structures. The core approach was to monitor the current (or resistance) change in these nanocomposite films, as cracks develop and propagate in the metallic host structure. Based on optical, electrical, and mechanical properties of epoxy resins modified with different contents of single-walled carbon nanotubes, two different nanocomposites (with 0.3 and 1.0 wt%) were chosen for the development of a crack sensor. The performance of the nanocomposite sensors was evaluated under tension-tension fatigue tests, on aluminum coupons with centrally located through thickness electrical discharge machining notches. Crack growth in the aluminum was found to transfer to the nanocomposite films in a stable mode. Once the crack was established, a linear correlation was found between the measured current and crack length with a slope of -10 -11 and -10 -8 A/mm for 0.3 and 1.0 wt% nanocomposites, respectively. Contact between the asperities formed on the crack surfaces in the nanocomposite film while the crack was closed at small loads (<30% of maximum load) was found to be an important limiting factor causing a large variation in measured currents during each fatigue cycle. Hence, a normalized variable based upon current change during each cycle was defined, providing a more accurate measurement of the crack size, with a crack gauge factor of ~0.04 mm -1. In summary, the nanocomposite thin film sensor developed in this study offers both continuous crack growth monitoring and the possibility of strain sensing. The sensor is also suitable for visual inspection of the host structure due to the transparency of the developed nanocomposite film. © The Author(s) 2012. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 54bcefca-a988-4609-8cbf-ad61697452cd ER - TY - JOUR TI - VLBI for Gravity Probe B. VII. the evolution of the radio structure of im Pegasi DO - 10.1088/0067-0049/201/1/7 AU - Bietenholz, M.F. AU - Bartel, N. AU - Lebach, D.E. AU - Ransom, R.R. AU - Ratner, M.I. AU - Shapiro, I.I. T2 - Astrophysical Journal, Supplement Series SN - 0067-0049 VL - 201 IS - 1 SP - 7 AB - We present measurements of the total radio flux density as well as very long baseline interferometry images of the star, IM Pegasi, which was used as the guide star for the NASA/Stanford relativity mission Gravity ProbeB. We obtained flux densities and images from 35 sessions of observations at 8.4GHz (λ = 3.6cm) between 1997 January and 2005 July. The observations were accurately phase-referenced to several extragalactic reference sources, and we present the images in a star-centered frame, aligned by the position of the star as derived from our fits to its orbital motion, parallax, and proper motion. Both the flux density and the morphology of IM Peg are variable. For most sessions, the emission region has a single-peaked structure, but 25% of the time, we observed a two-peaked (and on one occasion perhaps a three-peaked) structure. On average, the emission region is elongated by 1.4 ± 0.4mas (FWHM), with the average direction of elongation being close to that of the sky projection of the orbit normal. The average length of the emission region is approximately equal to the diameter of the primary star. No significant correlation with the orbital phase is found for either the flux density or the direction of elongation, and no preference for any particular longitude on the star is shown by the emission region. © 2012. The American Astronomical Society. All rights reserved.. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 04cc790c-e5a7-44dd-a0b8-f9414343a071 ER - TY - JOUR TI - Grating couplers in thick rib SOI waveguides for TE and TM polarizations DO - 10.1117/12.922713 AU - Alonso-Ramos, C. AU - Ortega-Moñux, A. AU - Halir, R. AU - Zavargo-Peche, L. AU - Molina-Fernández, I. AU - Cheben, P. AU - Xu, D.-X. AU - Janz, S. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Silicon Photonics and Photonic Integrated Circuits III, 16 April 2012 through 19 April 2012, Brussels SN - 0277-786X SN - 9780819491237 VL - 8431 SP - 84310E KW - Alignment tolerance KW - Coupling efficiency KW - Grating couplers KW - Grating design KW - Nanometrics KW - Rib waveguides KW - Silicon on insulator waveguide KW - SOI KW - SOI waveguides KW - TM polarization KW - Transverse-electric polarizations KW - Efficiency KW - Optical fiber coupling KW - Photonic devices KW - Photonic integration technology KW - Photonics KW - Polarization KW - Waveguides AB - Grating couplers have shown promising performance in terms of coupling efficiency and alignment tolerances as an interface between optical fibers and nanometric silicon-on-insulator (SOI) waveguides. In this paper we review our previous work, where the implementation of a fiber to chip grating coupler in micrometric rib SOI waveguide was demonstrated for the first time, showing measured coupling efficiency of -2.2dB for transverse-electric (TE) polarization. We also propose a new grating design that achieves a calculated coupling efficiency of -2dB for transverse-magnetic (TM) light. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7788ae5c-c815-4689-a163-1e18c3868217 ER - TY - JOUR TI - Gemini high-resolution optical spectrograph conceptual mechanical design DO - 10.1117/12.926836 AU - Hill, A. AU - Anthony, A. AU - Pazder, J. AU - Szeto, K. AU - Thibault, S. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Ground-Based and Airborne Instrumentation for Astronomy IV, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491473 VL - 8446 SP - 84462I KW - Design challenges KW - Echelle KW - Environmental stability KW - High resolution KW - Mechanical design KW - Multiobject KW - Optical spectrograph KW - Pick-off KW - Relay system KW - White pupil relay KW - Astrophysics KW - Charge coupled devices KW - Conceptual design KW - Fibers KW - Optical resolving power KW - Spectrographs AB - The Herzberg Institute of Astrophysics was recently selected by the Gemini Observatory as one of the three competing organizations to conduct a conceptual design study for a new Gemini High-Resolution Optical Spectrograph (GHOS). This paper outlines the main features of the mechanical design, including the Cassegrain-mounted science input unit, the bench-mounted spectrograph and the fiber relay system. Topics include the design challenges associated with multi-object fiber relays in the science unit, environmental stability of the spectrograph bench and routing and handling of fibers in the Gemini dome environment. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a2e8f309-ff72-4618-851c-094b3d616ebb ER - TY - JOUR TI - Helicobacter pylori 1,3-N-acetylglucosaminyltransferase for versatile synthesis of type 1 and type 2 poly-LacNAcs on N-linked, O-linked and I-antigen glycans DO - 10.1093/glycob/cws101 AU - Peng, W. AU - Pranskevich, J. AU - Nycholat, C. AU - Gilbert, M. AU - Wakarchuk, W. AU - Paulson, J.C. AU - Razi, N. T2 - Glycobiology SN - 0959-6658 VL - 22 IS - 11 SP - 1453 EP - 1464 KW - beta 3 n acetylglucosaminyltransferase KW - glycan derivative KW - glycopeptide KW - n acetylglucosamine KW - n acetylglucosaminyltransferase KW - unclassified drug KW - aminosugar KW - blood group I antigen KW - glycosphingolipid KW - I-antigen KW - n acetylglucosamine KW - n acetyllactosamine KW - N-acetyllactosamine KW - polylactosamine KW - polysaccharide KW - article KW - carbon nuclear magnetic resonance KW - enzyme activity KW - enzyme substrate complex KW - Helicobacter pylori KW - priority journal KW - protein motif KW - proton nuclear magnetic resonance KW - synthesis KW - biosynthesis KW - chemistry KW - enzymology KW - glycosylation KW - metabolism KW - Bacteria (microorganisms) KW - Helicobacter pylori KW - Acetylglucosamine KW - Amino Sugars KW - Glycosphingolipids KW - Glycosylation KW - Helicobacter pylori KW - N-Acetylglucosaminyltransferases KW - Polysaccharides AB - Poly-N-acetyllactosamine extensions on N-and O-linked glycans are increasingly recognized as biologically important structural features, but access to these structures has not been widely available. Here, we report a detailed substrate specificity and catalytic efficiency of the bacterial β3-N-acetylglucosaminyltransferase (β3GlcNAcT) from Helicobacter pylori that can be adapted to the synthesis of a rich diversity of glycans with poly-LacNAc extensions. This glycosyltransferase has surprisingly broad acceptor specificity toward type-1,-2,-3 and-4 galactoside motifs on both linear and branched glycans, found commonly on N-linked, O-linked and I-antigen glycans. This finding enables the production of complex ligands for glycan-binding studies. Although the enzyme shows preferential activity for type 2 (Galβ1-4GlcNAc) acceptors, it is capable of transferring N-acetylglucosamine (GlcNAc) in β1-3 linkage to type-1 (Galβ1-3GlcNAc) or type-3/4 (Gal1-3GalNAc/) sequences. Thus, by alternating the use of the H. pylori β3GlcNAcT with galactosyltransferases that make the 1-4 or 1-3 linkages, various N-linked, O-linked and I-antigen acceptors could be elongated with type-2 and type-1 LacNAc repeats. Finally, one-pot incubation of di-LacNAc biantennary N-glycopeptide with the β3GlcNAcT and GalT-1 in the presence of uridine diphosphate (UDP)-GlcNAc and UDP-Gal, yielded products with 15 additional LacNAc units on the precursor, which was seen as a series of sequential ion peaks representing alternative additions of GlcNAc and Gal residues, on matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis. Overall, our data demonstrate a broader substrate specificity for the H. pylori β3GlcNAcT than previously recognized and demonstrate its ability as a potent resource for preparative chemo-enzymatic synthesis of complex glycans. © 2012 The Author. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 029c1d00-b51d-4472-975f-d71c960a4c3a ER - TY - JOUR TI - Ultrasonic measurement of filler concentration AU - Fry, C. AU - Sun, Z. T2 - Annual Technical Conference - ANTEC, Conference Proceedings T3 - 70th Annual Technical Conference of the Society of Plastics Engineers 2012, ANTEC 2012, 2 April 2012 through 4 April 2012, Orlando, FL SN - 9781622760831 VL - 3 SP - 2214 EP - 2220 KW - Calibration process KW - Filler concentration KW - In-line KW - Novel techniques KW - Polymer flows KW - Ultrasonic inspections KW - Carbon black KW - Fillers KW - Plastic products KW - Polymers KW - Ultrasonic testing KW - Filled polymers AB - A novel technique for ultrasonic determination of filler concentration in polymers has been proposed and tested. The new technique senses the overall effect of the filler on the polymer flow behavior and uses this effect to infer the filler concentration. An in-line calibration process has been proposed and implemented for the application of the technique. An average estimation accuracy of better than 0.4% in weight on filler concentration has been achieved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 360680d5-6102-417c-82c6-e17f4e3581d5 ER - TY - JOUR TI - An observed lack of substructure in starless cores. II. super-jeans cores DO - 10.1088/0004-637X/755/2/178 AU - Schnee, S. AU - Sadavoy, S. AU - Di Francesco, J. AU - Johnstone, D. AU - Wei, L. T2 - The Astrophysical Journal SN - 0004-637X VL - 755 IS - 2 SP - 178 AB - We present SMA and CARMA continuum and spectral line observations of five dense cores located in the Perseus and Ophiuchus molecular clouds whose masses exceed their thermal Jeans masses. Three of these cores have previously been identified as being starless and two have been classified as being possibly protostellar. We find that one core is certainly protostellar. The other four cores, however, are starless and undetected in both C 18O and 1.3mm continuum emission. These four starless cores have flat density profiles out to at least ∼0.006pc, which is typical for starless cores in general. Density profiles predicted by some collapse models, especially in the early stages of infall, are consistent with our observations. Archival data reveal that these starless cores have significant non-thermal support against collapse, although they may still be unstable. © 2012. The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1b48001c-e99b-4899-89d7-f976370585d2 ER - TY - JOUR TI - Terahertz generation using implanted InGaAs photomixers and multi-wavelength quantum dot lasers DO - 10.3786/nml.v4i1.p10-13 AU - Hou, Y. AU - Liu, J.R. AU - Buchanan, M. AU - Spring Thorpe, A.J. AU - Poole, P.J. AU - Liu, H.C. AU - Wu, K. AU - Roorda, S. AU - Zhang, X.P. T2 - Nano-Micro Letters SN - 2150-5551 VL - 4 IS - 1 SP - 10 EP - 13 AB - We report on a study of terahertz (THz) generation using implanted InGaAs photomixers and multi-wavelength quantum dot lasers. We carry out InGaAs materials growth, optical characterization, device design and fabrication, and photomixing experiments. This approach is capable of generating a comb of electromagnetic radiation from microwave to terahertz. For shortening photomixer carrier lifetime, we employ proton implantation into an epitaxial layer of lattice matched InGaAs grown on InP. Under a 1.55 μm multimode InGaAs/InGaAsP quantum dot laser excitation, a frequency comb with a constant frequency spacing of 50 GHz generated on the photomixer is measured, which corresponds to the beats of the laser longitudinal modes. The measurement is performed with a Fourier transform infrared spectrometer. This approach affords a convenient method to achieve a broadband multi-peak coherent THz source. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 621d0852-edc8-4a87-bc0f-2240e8e9ee6a ER - TY - JOUR TI - Beam quality conversion factors for parallel-plate ionization chambers in MV photon beams DO - 10.1118/1.3687864 AU - Muir, B.R. AU - McEwen, M.R. AU - Rogers, D.W.O. T2 - Medical Physics SN - 0094-2405 VL - 39 IS - 3 SP - 1618 EP - 1631 KW - article KW - equipment KW - Monte Carlo method KW - photon KW - radiometry KW - time KW - uncertainty KW - Monte Carlo Method KW - Photons KW - Radiometry KW - Time Factors KW - Uncertainty AB - Purpose: To investigate the behavior of plane-parallel ion chambers in high-energy photon beams through measurements and Monte Carlo simulations. Methods: Ten plane-parallel ion chamber types were obtained from the major ion chamber manufacturers. Absorbed dose-to-water calibration coefficients are measured for these chambers and k Q factors are determined. In the process, the behaviors of the chambers are characterized through measurements of leakage currents, chamber settling in cobalt-60, polarity and ion recombination behavior, and long-term stability. Monte Carlo calculations of the absorbed dose to the air in the ion chamber and absorbed dose to water are obtained to calculate k Q factors. Systematic uncertainties in Monte Carlo calculated k Q factors are investigated by varying material properties and chamber dimensions. Results: Chamber behavior was variable in MV photon beams, especially with regard to chamber leakage and ion recombination. The plane-parallel chambers did not perform as well as cylindrical chambers. Significant differences up to 1.5 were observed in calibration coefficients after a period of eight months although k Q factors were consistent on average within 0.17. Chamber-to-chamber variations in k Q factors for chambers of the same type were at the 0.2 level. Systematic uncertainties in Monte Carlo calculated k Q factors ranged between 0.34 and 0.50 depending on the chamber type. Average percent differences between measured and calculated k Q factors were - 0.02, 0.18, and - 0.16 for 6, 10, and 25 MV beams, respectively. Conclusions: Excellent agreement is observed on average at the 0.2 level between measured and Monte Carlo calculated k Q factors. Measurements indicate that the behavior of these chambers is not adequate for their use for reference dosimetry of high-energy photon beams without a more extensive QA program than currently used for cylindrical reference-class ion chambers. © 2012 American Association of Physicists in Medicine. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a16b754e-c906-4d69-b0c3-2b77e46e23aa ER - TY - JOUR TI - Demonstration of a curved sidewall grating demultiplexer on silicon DO - 10.1364/OE.20.019882 AU - Bock, Przemek J. AU - Cheben, Pavel AU - Schmid, Jens H. AU - Velasco, Aitor V. AU - Delâge, André AU - Janz, Siegfried AU - Xu, Dan-Xia AU - Lapointe, Jean AU - Hall, Trevor J. AU - Calvo, María L. T2 - Optics Express SN - 1094-4087 VL - 20 IS - 18 SP - 19882 EP - 19892 KW - Compact devices KW - Cross-talk levels KW - Demultiplexers KW - Nanophotonic circuits KW - Silicon photonics KW - Wavelength ranges KW - Nanophotonics KW - Photonics KW - silicon KW - article KW - chemistry KW - equipment design KW - equipment failure analysis KW - instrumentation KW - nanotechnology KW - refractometry KW - surface plasmon resonance KW - telecommunication KW - Equipment Design KW - Equipment Failure Analysis KW - Nanotechnology KW - Refractometry KW - Silicon KW - Surface Plasmon Resonance KW - Telecommunications AB - We experimentally demonstrate a new type of waveguide multiplexer device designed for silicon photonics, with a crosstalk level as low as -35 dB and an operational wavelength range of 300 nm. A compact device footprint of only 100 × 160 μ m 2 offers an excellent potential for integration with other silicon nanophotonic circuits. © 2012 Optical Society of America. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d5dec043-9bcd-4a17-b0b8-a8fbbdf3ae60 ER - TY - JOUR TI - CFD investigation of noise around a landing gear AU - Fortin, F. AU - Syms, J. AU - Clark, C. AU - McIlwain, S. T2 - 18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference) T3 - 18th AIAA/CEAS Aeroacoustics Conference 2012 (33rd AIAA Aeroacoustics Conference), 4 June 2012 through 6 June 2012 SN - 9781600869327 KW - Complex geometries KW - Experimental datum KW - Far-field noise KW - Flow solver KW - Jet wind tunnels KW - Near-field KW - Acoustic noise KW - Computational fluid dynamics KW - Landing gear (aircraft) KW - Aeroacoustics AB - A scaled landing gear has recently been tested in the NRC 0.9 m 3/4-open jet wind tunnel. It provided experimental data that were used to investigate the capability and methodology of a CFD flow solver to predict adequately the noise generated on the landing gear surfaces and in its wake. Near-field and far-field noise predictions using CFD were carried out. FFTs of the landing gear surfaces for a given frequency were also carried out. Comparison of the results demonstrates that CFD can predict adequately the noise around complex geometries such as landing gears. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3ec820e5-4d4a-43b0-b045-9a63b7835e92 ER - TY - JOUR TI - Investigation of skin porosity damping effects on free stream disturbance induced unsteady wing loads AU - Dahdi, B. AU - Mamou, M. AU - Khalid, M. AU - Benissaad, S. AU - Nemouchi, Z. T2 - Aeronautical Journal SN - 0001-9240 VL - 116 IS - 1184 SP - 1041 EP - 1060 KW - Cylinder wake KW - Damping effect KW - Discrete vortices KW - Disturbance level KW - Flat plate KW - Flow configurations KW - Free stream KW - Leading edge KW - Lift coefficient KW - Shedding vortex KW - Steady-state flows KW - Unsteady effects KW - Unsteady reynolds-averaged navier-stokes KW - Wing load KW - Circular cylinders KW - Damping KW - Flow simulation KW - Lift KW - Porosity KW - Wakes KW - Vortex flow AB - Numerical simulations were performed to analyse the possibility of damping abrupt incoming free stream disturbances upon a porous aerofoil using an unsteady Reynolds-averaged Navier-Stokes (URANS) model. To mimic the turbulence disturbance levels that are typically encountered in the atmosphere, two flow configurations were considered. In the first configuration, the unsteadiness of the flow was created with vortices shed from a circular cylinder installed ahead of a WTEA-TE1 aerofoil. The continuous von Kármán shedding vortices contained within the cylinder wake were convected downstream and projected upon the aerofoil. In the second configuration, an instantaneous pair of discrete vortices was created by a rotational snapping of a flat plate, installed upstream of the aerofoil. Solid and porous aerofoil configurations, with porosity settings of 11 and 22%, were applied on 50% of the chord of the aerofoil starting from the leading edge. Both steady and unsteady flow simulations were performed to assess the performance of the porosity under steady and unsteady effects. The steady state flow simulations revealed a noticeable reduction in the aerofoil lift coefficient for the porous aerofoil. For unsteady solutions with a continuous or distinct series of vortices interacting with the aerofoil, the porosity showed insignificant damping of the lift coefficient amplitude. The porosity values investigated in the current exercise had indiscernible effect upon the unsteady lift-load alleviations caused by free stream disturbances. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5025c2be-efdf-40ac-940f-f7e80592c090 ER - TY - JOUR TI - The fine structure of a triexciton in single InAs/GaAs quantum dots AU - Molas, M. AU - Gołasa, K. AU - Furman, M. AU - Lapointe, J. AU - Wasilewski, Z.R. AU - Potemski, M. AU - Babiński, A. T2 - Acta Physica Polonica A SN - 0587-4246 VL - 122 IS - 6 SP - 991 EP - 993 KW - Electrons and holes KW - Emission lines KW - Experimental studies KW - Fine structure splitting KW - Fine structures KW - InAs/GaAs quantum dots KW - Linearly polarized KW - Low temperatures KW - Microphotoluminescence KW - Neutral excitons KW - P-shell KW - Self-assembled KW - Electromagnetic wave emission KW - Excitons KW - Optical anisotropy KW - Optical properties KW - Polarization KW - Semiconductor quantum dots AB - Results of experimental study of multiexcitonic emission related to the p-shell of single self-assembled InAs/GaAs quantum dots are presented. Optical properties of a first emission line to appear from the p-shell of a strongly excited quantum dots are investigated using low-temperature polarization- sensitive micro-photoluminescence measurements. The emission line is attributed to the recombination of a complex of three electrons and holes confined in a dot (neutral triexciton), 3X. It is found that the emission consists of two linearly polarized components and the fine structure splitting is larger than the respective splitting of a neutral exciton. The optical anisotropy of the 3X emission is related to the anisotropy of the quantum dot localizing potential. The axis of the 3X optical anisotropy changes from dot to dot covering broad range within ±50 degrees with respect to the axis defined by the optical anisotropy of a neutral exciton (X). Possible origin of the deviation is discussed. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5683198b-d0b9-418b-ad44-3fa3745cac5b ER - TY - JOUR TI - Sizes of galactic globular clusters DO - 10.1088/0004-637X/746/2/189 AU - Van Den Bergh, S. T2 - The Astrophysical Journal SN - 0004-637X VL - 746 IS - 2 SP - 189 AB - A study is made of deviations from the mean power-law relationship between the Galactocentric distances and the half-light radii of Galactic globular clusters. Surprisingly, deviations from the mean R h versus R gc relationship do not appear to correlate with cluster luminosity, cluster metallicity, or horizontal-branch morphology. Differences in orbit shape are found to contribute to the scatter in the R h versus R gc relationship of Galactic globular clusters. © 2012. The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7f3c3e9b-8c3f-4824-b5c3-318e6c0755f0 ER - TY - JOUR TI - A high-performance FPGA platform for adaptive optics real-time control DO - 10.1117/12.925479 AU - Zhang, H. AU - Ljusic, Z. AU - Hovey, G. AU - Veran, J.-P. AU - Herriot, G. AU - Dumas, M. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Adaptive Optics Systems III, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491480 VL - 8447 SP - 84472E KW - AdvancedTCA KW - Architecture platforms KW - Astrophysical observatory KW - Deformable mirrors KW - Ground-based telescopes KW - Hardware platform KW - Hardware resources KW - High-performance computing KW - Kermode Board KW - Memory bandwidths KW - Multi-conjugate adaptive optics systems KW - NFIRAOS KW - Pixel processing KW - Processing power KW - Real time tomography KW - Second generation KW - Software development kit KW - Terabit KW - Thirty Meter Telescope KW - Tomographic KW - Wave front reconstruction KW - Adaptive optics KW - Computer software selection and evaluation KW - Control systems KW - Firmware KW - Hardware KW - Optical telescopes KW - Real time control KW - Telescopes KW - Tomography KW - Field programmable gate arrays (FPGA) AB - Adaptive Optics Real-Time Control systems for next generation ground-based telescopes demand significantly higher processing power, memory bandwidth and I/O capacity on the hardware platform than those for existing control systems. We present a FPGA based high-performance computing platform that is developed at Dominion Radio Astrophysical Observatory and is very suitable for the applications of Adaptive Optics Real-Time Control systems. With maximum of 16 computing blades, 110 TeraMAC/s processing power, 1.8Terabyte/s memory bandwidth and 19.5 Terabit/s I/O capacity, this ATCA architecture platform has enough capacity to perform pixel processing, tomographic wave-front reconstruction and deformable mirror fitting for first and second generation AO systems on 30+-meter class telescopes. As an example, we demonstrate that with only one computing blade, the platform can handle the real time tomography needs of NFIRAOS, the Thirty-Meter Telescope first light facility Multi-Conjugate Adaptive Optics system. The High-Performance FPGA platform is integrated with Board Software Development Kit to provide a complete and fully tested set of interfaces to access the hardware resources. Therefore the firmware development can be focused on unique, user-specific applications. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f182e373-1ed1-4856-93b5-29c48b25ae9b ER - TY - JOUR TI - Improved stress intensity factor solutions for surface and corner cracks at a hole DO - 10.2514/6.2012-1700 AU - Renaud, Guillaume AU - Liao, Min AU - Bombardier, Yan T2 - 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference 2012 T2 - A Collection of Technical Papers on ... T3 - 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference 2012, April 23-26 2012, Honolulu, HI SN - 0273-4508 SN - 9781600869372 KW - corner cracks KW - correction approaches KW - modeling and analysis KW - semi-elliptical crack KW - surface cracks KW - thickness direction KW - three dimensional finite elements KW - uniaxial tensile loading KW - finite element method KW - stress intensity factors KW - structural dynamics KW - surface defects KW - cracks AB - Detailed three-dimensional finite element (FE) modeling and analysis of quarter-elliptical and semi-elliptical cracks at a hole were carried out. Comparison cases showed that the accuracy of the classical Newman-Raju closed-form stress intensity factor solutions can be improved, especially for the surface crack case and in the thickness direction for the corner crack case. Using the developed FE models, improved stress intensity factor solutions for quarter-circular and semi-circular cracks at a hole were obtained for uniaxial tensile loading. A simple correction approach is also proposed to improve the accuracy of the Newman-Raju solutions for more general cases of quarter-elliptical and semi-elliptical cracks at a hole. DA - 2012/04 PY - 2012 PB - American Institute of Aeronautics and Astronautics LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3cfdfc77-e7fb-4ebc-b2e9-6e6d7457e1c9 ER - TY - JOUR TI - Consistent point clouds of narrow dpaces using multiscan domain mapping DO - 10.1111/j.1467-8667.2011.00742.x AU - Sareen, K.K. AU - Knopf, G.K. AU - Canas, R. T2 - Computer-Aided Civil and Infrastructure Engineering SN - 1093-9687 VL - 27 IS - 8 SP - 555 EP - 572 KW - Civil structure KW - Data approximation KW - Data density KW - Data-acquisition devices KW - Density variations KW - Domain mapping KW - Experimental observation KW - Incident angles KW - Inconsistent data KW - Large spaces KW - Laser scanner KW - Limited data KW - Multi-scan KW - Partial scan KW - Planning methodology KW - Point cloud KW - Point-based visualization KW - Scanning range KW - Stationary positions KW - Scanning KW - Three dimensional KW - Visualization KW - Data visualization KW - accuracy assessment KW - civil engineering KW - data acquisition KW - experimental study KW - observational method KW - structural analysis KW - three-dimensional modeling KW - visualization AB - Three-dimensional (3D) range scanning of large spaces, such as civil structures, generates an immense cloud of 3D points with inconsistent data densities due to the limited positions of the stationary scanner, inaccessible surfaces, and narrow pathways. This density variation is the dominant detrimental factor in extracting accurate scanned shapes. This article introduces an effective scan planning methodology for capturing accurate geometry from long and narrow spaces, which minimizes the need for subsequent data approximations. The technique computes an optimum scanning range for each stationary position of the scanner that limits the density variation to a user-defined value. Three cases are proposed to define the "limited data density" and a FARO®-LS880 laser scanner is used to illustrate the proposed approach that achieves acceptable scanning results in terms of its critical shape capturing capability, overall point cloud density, and accurate point-based visualization. The experimental observations confirm that the accuracy of the scanned data can be improved by registering multiple partial scans with restricted density and positioning the data acquisition device close to the critical features. The latter recommended step decreases the incident angle to the world domain, which, in turn, reduces the surface occlusions and data density variations. © 2011 Computer-Aided Civil and Infrastructure Engineering. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 82db7e20-499e-48aa-8268-5a25b7c39cba ER - TY - CHAP TI - Optical Coherence Tomography for Document Security and Biometrics DO - 10.1002/9781118310212.ch7 AU - Chang, S. AU - Mao, Y. AU - Flueraru, C. T2 - Photonic Sensing: Principles and Applications for Safety and Security Monitoring SN - 9780470626955 SP - 225 EP - 257 DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9b4e705d-62ba-4a95-ada5-b317a080d8fb ER - TY - JOUR TI - An empirical measure of the rate of white dwarf cooling in 47 Tucanae DO - 10.1088/0004-637X/760/1/78 AU - Goldsbury, R. AU - Heyl, J. AU - Richer, H.B. AU - Bergeron, P. AU - Dotter, A. AU - Kalirai, J.S. AU - MacDonald, J. AU - Rich, R.M. AU - Stetson, P.B. AU - Tremblay, P.-E. AU - Woodley, K.A. T2 - The Astrophysical Journal SN - 0004-637X VL - 760 IS - 1 SP - 78 AB - We present an empirical determination of the white dwarf cooling sequence in the globular cluster 47 Tucanae. Using spectral models, we determine temperatures for 887 objects from Wide Field Camera 3 data, as well as 292 objects from data taken with the Advanced Camera for Surveys. We make the assumption that the rate of white dwarf formation in the cluster is constant. Stellar evolution models are then used to determine the rate at which objects are leaving the main sequence, which must be the same as the rate at which objects are arriving on the white dwarf sequence in our field. The result is an empirically derived relation between temperature (T eff and time (t) on the white dwarf cooling sequence. Comparing this result to theoretical cooling models, we find general agreement with the expected slopes between 20,000K and 30,000K and between 6000K and 20,000K, but the transition to the Mestel cooling rate of T efft -0.4 is found to occur at hotter temperatures, and more abruptly than is predicted by any of these models. © 2012. The American Astronomical Society. All rights reserved.. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8555a3ad-6b23-451f-b12b-fb8581fab82d ER - TY - JOUR TI - Linear friction welding of a single crystal superalloy DO - 10.4028/www.scientific.net/MSF.706-709.3022 AU - Wanjara, P. AU - Dalgaard, E. AU - Gholipour, J. AU - Larose, J. T2 - Materials Science Forum T3 - 7th International Conference on Processing and Manufacturing of Advanced Materials, THERMEC'2011, 1 August 2011 through 5 August 2011, Quebec City, QC SN - 0255-5476 SN - 9783037853030 VL - 706-709 SP - 3022 EP - 3027 KW - Forging pressures KW - Linear friction welding KW - Microhardness testing KW - Microstructural examination KW - Microstructural features KW - Ni-based superalloys KW - Parent materials KW - Recrystallized grains KW - Single crystal Ni-based superalloys KW - Single crystal superalloys KW - Thermomechanically affected zones KW - Weld zone KW - Welded materials KW - Friction welding KW - Microstructural evolution KW - Recrystallization (metallurgy) KW - Single crystals KW - Strength of materials KW - Superalloys KW - Welds KW - Crystal orientation KW - Friction KW - Tribology KW - Welding AB - The effect of forging pressure on linear friction welding (LFW) behaviour of a single crystal Ni-based superalloy was investigated. Crystal orientations of the specimens were controlled and results indicated that welding success is dependent on proximity of the oscillation direction to the <011> direction. Characterization of the welds included optical examination of the microstructural features of the weld and thermomechanically affected zones (TMAZ) in relation to the parent material. Mechanical properties of the welded material examined via microhardness testing showed an increase in strength in the weld zone (WZ). Microstructural examination indicated that some recrystallization occurred in the WZ, as well as a small amount of distortion of the dendrites in the TMAZ. With increased forge pressure, recrystallized grains remaining in the weld were minimized. © 2012 Trans Tech Publications, Switzerland. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 24949def-39bf-425f-b046-4fc731a8a0ae ER - TY - JOUR TI - Ultra-compact polarization mode converter implemented in a dual-trench silicon-on-insulator waveguide DO - 10.1364/CLEO_SI.2012.CM4M.5 AU - Velasco, Aitor V. AU - Calvo, María L. AU - Cheben, Pavel AU - Ortega-Moñux, Alejandro AU - Schmid, Jens H. AU - Ramos, Carlos Alonso AU - Fernandez, Íñigo Molina AU - Lapointe, Jean AU - Vachon, Martin AU - Janz, Siegfried AU - Xu, Dan-Xia T2 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012 T3 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012, 6 May 2012 through 11 May 2012, San Jose, CA SN - 9781467318396 SP - 6325812 KW - Extinction ratios KW - Polarization mode converter KW - Silicon on insulator waveguide KW - Sub-wavelength KW - Lasers AB - We demonstrate an ultracompact polarization mode converter based on a silicon-on-insulator waveguide with two longitudinal subwavelength trenches. An extinction ratio of 16 dB at 1.5 μm is achieved for a device length of 10 μm. © 2012 OSA. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 45d32756-0474-4790-8480-5eb9ec4bca6e ER - TY - JOUR TI - The dependence of quenching upon the inner structure of galaxies at 0.5 ≤ z < 0.8 in the deep2/aegis survey DO - 10.1088/0004-637X/760/2/131 AU - Cheung, E. AU - Faber, S.M. AU - Koo, D.C. AU - Dutton, A.A. AU - Simard, L. AU - McGrath, E.J. AU - Huang, J.-S. AU - Bell, E.F. AU - Dekel, A. AU - Fang, J.J. AU - Salim, S. AU - Barro, G. AU - Bundy, K. AU - Coil, A.L. AU - Cooper, M.C. AU - Conselice, C.J. AU - Davis, M. AU - Domínguez, A. AU - Kassin, S.A. AU - Kocevski, D.D. AU - Koekemoer, A.M. AU - Lin, L. AU - Lotz, J.M. AU - Newman, J.A. AU - Phillips, A.C. AU - Rosario, D.J. AU - Weiner, B.J. AU - Willmer, C.N.A. T2 - The Astrophysical Journal SN - 0004-637X VL - 760 IS - 2 SP - 131 AB - The shutdown of star formation in galaxies is generally termed "quenching." Quenching may occur through a variety of processes, e.g., active galactic nucleus (AGN) feedback, stellar feedback, or the shock heating of gas in the dark matter halo. However, which mechanism(s) is, in fact, responsible for quenching is still in question. This paper addresses quenching by searching for traces of possible quenching processes through their effects on galaxy structural parameters such as stellar mass (M), M/re, surface stellar mass density (M/r 2e), and Sérsic index (n). We analyze the rest-frame U - B color correlations versus these structural parameters using a sample of galaxies in the redshift range 0.5 ≤ z < 0.8 from the DEEP2/AEGIS survey. In addition to global radii, stellar masses, and Sérsic parameters, we also use "bulge" and "disk" photometric measurements from GIM2D fits to HST/ACS V and I images. We assess the tightness of the color relationships by measuring their "overlap regions," defined as the area in color-parameter space in which red and blue galaxies overlap; the parameter that minimizes these overlap regions is considered to be the most effective color discriminator. We find that Sérsic index (n) has the smallest overlap region among all tested parameters and resembles a step function with a threshold value of n = 2.3. There exists, however, a significant population of outliers with blue colors yet high n values that seem to contradict this behavior; they make up 40% of n > 2.3 galaxies. We hypothesize that their Sérsic values may be distorted by bursts of star formation, AGNs, and/or poor fits, leading us to consider central surface stellar mass density, Σ1 kpc, as an alternative to Sérsic index. Not only does Σ1 kpc correct the outliers, but it also forms a tight relationship with color, suggesting that the innermost structure of galaxies is most physically linked with quenching. Furthermore, at z 0.65, the majority of the blue cloud galaxies cannot simply fade onto the red sequence since their GIM2D bulge masses are only half as large on average as the bulge masses of similar red sequence galaxies, thus demonstrating that stellar mass must absolutely increase at the centers of galaxies as they quench. We discuss a two-stage model for quenching in which galaxy star formation rates are controlled by their dark halos while they are still in the blue cloud and a second quenching process sets in later, associated with the central stellar mass buildup. The mass buildup is naturally explained by any non-axisymmetric features in the potential, such as those induced by mergers and/or disk instabilities. However, the identity of the second quenching agent is still unknown. We have placed our data catalog online. © 2012. The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7961b47f-67bd-40d6-94d0-1605764540b6 ER - TY - JOUR TI - Astronomical sky quality near Eureka, in the Canadian high arctic DO - 10.1086/664444 AU - Steinbring, E. AU - Ward, W. AU - Drummond, J.R. T2 - Publications of the Astronomical Society of the Pacific SN - 0004-6280 VL - 124 IS - 912 SP - 185 EP - 194 AB - Nighttime visible-light sky brightness and transparency are reported for the Polar Environment Research Laboratory (PEARL), located on a 610 m high ridge near the Eureka research station at 80° latitude, on Ellesmere Island, Canada. Photometry of Polaris obtained in the V band with the PEARL All Sky Imager (PASI) over two winters is supported by standard meteorological measurements and visual estimates of sky conditions from sea level. These data show that during the period of the study, 2008/2009 and 2009/2010 October through March, the sky near zenith had a mean surface brightness of 19:7 mag arcsec -2 when the Sun was more than 12° below the horizon, reaching 20:7 mag arcsec -2 during astronomical darkness with no Moon. Skies were without thick cloud and potentially usable for astronomy 86% of the time (extinction <2 mag). Up to 68% of the time was spectroscopic (≤0:5 mag), attenuated by ice crystals, or clear with stable atmospheric transparency. Those conditions can persist for over 100 hr at a time. Further analysis suggests the sky was entirely free of ice crystals (truly photometric) 48 ± 3% of the time at PEARL in winter and that a higher elevation location nearby may be better. © 2012. The Astronomical Society of the Pacific. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 54fcd3b3-6322-4e15-aef0-2464134b4cfc ER - TY - JOUR TI - New exoplanet surveys in the Canadian High Arctic at 80 Degrees North DO - 10.1117/12.926338 AU - Law, N.M. AU - Sivanandam, S. AU - Murowinski, R. AU - Carlberg, R. AU - Ngan, W. AU - Salbi, P. AU - Ahmadi, A. AU - Steinbring, E. AU - Halman, M. AU - Graham, J. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Ground-Based and Airborne Telescopes IV, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491459 VL - 8444 SP - 84445C KW - Astronomical surveys KW - Detection efficiency KW - Exo-planets KW - Exoplanet KW - Field of views KW - Fields of views KW - High arctic KW - Low-mass stars KW - Polaris KW - Robotic telescope KW - Search system KW - Snapshot images KW - Wide field cameras KW - Wide field imaging KW - Airborne telescopes KW - Conceptual design KW - Instrument testing KW - Optical telescopes KW - Planets KW - Search engines KW - Stars KW - Surveys AB - Observations from near the Eureka station on Ellesmere Island, in the Canadian High Arctic at 80° North, benefit from 24-hour darkness combined with dark skies and long cloud-free periods during the winter. Our first astronomical surveys conducted at the site are aimed at transiting exoplanets; compared to mid-latitude sites, the continuous darkness during the Arctic winter greatly improves the survey's detection efficiency for longer-period transiting planets. We detail the design, construction, and testing of the first two instruments: a robotic telescope, and a set of very wide-field imaging cameras. The 0.5m Dunlap Institute Arctic Telescope has a 0.8-square-degree field of view and is designed to search for potentially habitable exoplanets around low-mass stars. The very wide field cameras have several-hundred-square-degree fields of view pointed at Polaris, are designed to search for transiting planets around bright stars, and were tested at the site in February 2012. Finally, we present a conceptual design for the Compound Arctic Telescope Survey (CATS), a multiplexed transient and transit search system which can produce a 10,000-square-degree snapshot image every few minutes throughout the Arctic winter. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c9f4b5c2-d3e8-4b4b-bdc9-0e51a4bf97e8 ER - TY - JOUR TI - A hexane fraction of American ginseng suppresses mouse colitis and associated colon cancer: Anti-inflammatory and proapoptotic mechanisms DO - 10.1158/1940-6207.CAPR-11-0421 AU - Poudyal, D. AU - Le, P.M. AU - Davis, T. AU - Hofseth, A.B. AU - Chumanevich, A. AU - Chumanevich, A.A. AU - Wargovich, M.J. AU - Nagarkatti, M. AU - Nagarkatti, P.S. AU - Windust, A. AU - Hofseth, L.J. T2 - Cancer Prevention Research SN - 1940-6207 VL - 5 IS - 4 SP - 685 EP - 696 KW - acetic acid ethyl ester KW - azoxymethane KW - butanol KW - dextran sulfate KW - dichloromethane KW - ginseng extract KW - hexane KW - water KW - antiinflammatory agent KW - plant extract KW - animal cell KW - antiinflammatory activity KW - antineoplastic activity KW - antioxidant activity KW - article KW - colitis KW - colon cancer KW - controlled study KW - ginseng KW - human KW - human cell KW - in vitro study KW - lymphoblastoid cell line KW - macrophage KW - nick end labeling KW - nonhuman KW - priority journal KW - animal KW - apoptosis KW - bioassay KW - chemistry KW - colon tumor KW - inflammation KW - mass fragmentography KW - metabolism KW - methodology KW - mouse KW - Panax KW - tumor cell line KW - ulcerative colitis KW - Animals KW - Anti-Inflammatory Agents KW - Apoptosis KW - Biological Assay KW - Cell Line, Tumor KW - Colitis, Ulcerative KW - Colonic Neoplasms KW - Gas Chromatography-Mass Spectrometry KW - Hexanes KW - Humans KW - In Situ Nick-End Labeling KW - Inflammation KW - Mice KW - Panax KW - Plant Extracts AB - Ulcerative colitis is a chronic inflammatory condition associated with a high colon cancer risk. We have previously reported that American ginseng extract significantly reduced the inflammatory parameters of chemically induced colitis. The aim of this study was to further delineate the components of American ginseng that suppress colitis and prevent colon cancer. Among five different fractions of American ginseng (butanol, hexane, ethylacetate, dichloromethane, and water), a hexane fraction has particularly potent antioxidant and proapoptotic properties. The effects of this fraction were shown in a mouse macrophage cell line (ANA-1 cells), in a human lymphoblastoid cell line (TK6), and in an ex vivo model (CD4 +/CD25 - primary effector T cells). A key in vivo finding was that compared with the whole American ginseng extract, the hexane fraction of American ginseng was more potent in treating colitis in a dextran sodium sulfate (DSS) mouse model, as well as suppressing azoxymethane/DSS-induced colon cancer. Furthermore, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) labeling of inflammatory cells within the colonic mesenteric lymph nodes was elevated in mice consuming DSS + the hexane fraction of American ginseng. Results are consistent with our in vitro data and with the hypothesis that the hexane fraction of American ginseng has anti-inflammatory properties and drives inflammatory cell apoptosis in vivo, providing a mechanism by which this fraction protects from colitis in this DSS mouse model. This study moves us closer to understanding the molecular components of American ginseng that suppress colitis and prevent colon cancer associated with colitis. ©2012 AACR. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e5609b86-9ac9-477e-ba7a-268e08051c65 ER - TY - JOUR TI - Mechanical and microstructural characterization of 45S5 Bioglass® scaffolds for tissue engineering AU - Aguilar-Reyes, E.A. AU - León-Patiño, C.A. AU - Jacinto-Díaz, B. AU - Lefebvre, L.-P. T2 - Ceramic Transactions T3 - Next Generation Biomaterials and Surface Properties of Biomaterials Symposia - Materials Science and Technology 2011 Conference and Exhibition, MS and T 2011, 16 October 2011 through 20 October 2011, Columbus, OH SN - 1042-1122 SN - 9781118273326 VL - 237 SP - 1 EP - 9 KW - 45S5 bioglass KW - Bone ingrowth KW - Dry powders KW - Micro-structural characterization KW - National Research Council KW - Powder mixtures KW - Primary phase KW - Scaffolds for tissue engineering KW - Secondary phase KW - Biological materials KW - Bone KW - Ceramic foams KW - Characterization KW - Powder metallurgy KW - Sintering KW - Sodium KW - Surface properties KW - Bioactive glass AB - Bioglass® 45S5 is the most widely investigated bioactive glass. It was recently demonstrated that this glass is better integrated into bone when the structure is porous. The National Research Council Canada has recently developed a process to produce metallic and ceramic foams using a powder metallurgy approach. Preliminary tests showed that Bioglass® foams can be produced with this process. These foams are produced by foaming a powder mixture composed of Bioglass® particles, a binder and a foaming agent. Highly porous Bioglass® foams (64-79% porosity) were successfully synthesized from dry powder blends. The porosity of the resulting foams was open and the pore size was essentially between 175 and 880 μm in diameter, as required for bone ingrowth. During sintering, crystallization took place and Na6Ca 3Si6O18 (primary phase) and Na 2Ca4(PO4)2SiO4 (secondary phase) were observed. The mechanical compressive strength ranged from 1.7 to 5.5 MPa. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2e2db8db-332a-44d1-a5b1-f7e3d6b1a98d ER - TY - JOUR TI - The N-terminal β-sheet of the hyperthermophilic endoglucanase from Pyrococcus horikoshii is critical for thermostability DO - 10.1128/AEM.07576-11 AU - Yang, T.C. AU - Legault, S. AU - Kayiranga, E.A. AU - Kumaran, J. AU - Ishikawa, K. AU - Sung, W.L. T2 - Applied and Environmental Microbiology SN - 0099-2240 VL - 78 IS - 9 SP - 3059 EP - 3067 KW - Active site KW - Bioinformatics analysis KW - C-terminal sequences KW - Core structure KW - Crystalline cellulose KW - Glucosidase KW - High temperature KW - Hydrolyzing activity KW - Hyperthermophilic archaeon KW - Hyperthermophilic endoglucanase KW - Hyperthermostability KW - Key residues KW - N-terminals KW - PH stability KW - Pyrococcus horikoshii KW - TIM barrels KW - Triosephosphate isomerase KW - Wild types KW - Bioinformatics KW - Cellulose KW - Enzymes KW - Ethanol KW - Glucose KW - Hydrolysis KW - Industrial applications KW - Crystal structure KW - cellulase KW - bioinformatics KW - cellulose KW - enzyme activity KW - gene expression KW - high temperature KW - thermophilic bacterium KW - amino acid sequence KW - article KW - chemistry KW - enzyme stability KW - enzymology KW - gene deletion KW - genetics KW - heat KW - molecular genetics KW - pH KW - protein conformation KW - protein stability KW - protein tertiary structure KW - Pyrococcus horikoshii KW - Amino Acid Sequence KW - Cellulase KW - Enzyme Stability KW - Hot Temperature KW - Hydrogen-Ion Concentration KW - Molecular Sequence Data KW - Protein Conformation KW - Protein Stability KW - Protein Structure, Tertiary KW - Pyrococcus horikoshii KW - Sequence Deletion KW - Archaea KW - Pyrococcus horikoshii AB - The β-1,4-endoglucanase (EC 3.2.1.4) from the hyperthermophilic archaeon Pyrococcus horikoshii (EGPh) has strong hydrolyzing activity toward crystalline cellulose. When EGPh is used in combination with β-glucosidase (EC 3.2.1.21), cellulose is completely hydrolyzed to glucose at high temperature, suggesting great potential for EGPh in bioethanol industrial applications. The crystal structure of EGPh shows a triosephosphate isomerase (TIM) (β/α)8-barrel fold with an N-terminal antiparallel β-sheet at the opposite side of the active site and a very short C-terminal sequence outside of the barrel structure. We describe here the function of the peripheral sequences outside of the TIM barrel core structure. Sequential deletions were performed from both N and C termini. The activity, thermostability, and pH stability of the expressed mutants were assessed and compared to the wildtype EGPh enzyme. Our results demonstrate that the TIM barrel core is essential for enzyme activity and that the N-terminal β-sheet is critical for enzyme thermostability. Bioinformatics analyses identified potential key residues which may contribute to enzyme hyperthermostability. © 2012, American Society for Microbiology. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8840a4f5-f407-4b8f-83ff-c35f4d400135 ER - TY - JOUR TI - Hybrid laser-arc welding of HSLA-65 steel plate: Microstructural and mechanical property evaluation of butt welds DO - 10.4028/www.scientific.net/MSF.706-709.2992 AU - Munro, C. AU - Nolting, A. AU - Cao, X. AU - Wanjara, P. T2 - Materials Science Forum T3 - 7th International Conference on Processing and Manufacturing of Advanced Materials, THERMEC'2011, 1 August 2011 through 5 August 2011, Quebec City, QC SN - 0255-5476 SN - 9783037853030 VL - 706-709 SP - 2992 EP - 2997 KW - Arc KW - Butt welds KW - Heat input KW - High heat input welding KW - High strength KW - High strength low alloy steels KW - HSLA-65 KW - Hybrid KW - Hybrid fibres KW - Laser-arc KW - MAG KW - Mechanical property evaluation KW - Metal arc welding KW - Micro-structural KW - Ship-building steels KW - Single pass KW - Steel plates KW - Thick plate KW - Welding-induced distortion KW - Alloy steel KW - Electric welding KW - Gas metal arc welding KW - High strength alloys KW - Impact testing KW - Lasers KW - Mechanical properties KW - Steel fibers KW - Welding KW - Welds KW - Hybrid materials KW - Shipbuilding materials KW - Ships KW - Strength of materials KW - High strength steel AB - High strength low alloy (HSLA) steel, namely HSLA-65, has shown promise as a replacement for more common high strength shipbuilding steels. However, conventional high heat input welding processes can cause significant distortion, often requiring expensive post-weld reworking. Butt welds in HSLA-65 steel were fabricated using a hybrid fibre laser-gas metal arc welding (GMAW) procedure to investigate the efficacy of distortion mitigation via low heat input joining. Heat input from the laser and arc sources were roughly equal at ∼5.2 kW each, and plates were welded in either the laser-leading or arc-leading configuration. In either case, butt welds in ∼9 mm thick plates could be made in a single pass at a total heat input of ∼0.4 kJ/mm. Welding induced distortion was minimal. Analysis of the microstructure and microhardness of the welds is provided, along with some preliminary results of mechanical and impact testing. © 2012 Trans Tech Publications, Switzerland. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a0558147-719a-4469-88bb-cee864bfcc9f ER - TY - JOUR TI - The microstructure, creep, and hardness properties of powder metallurgy beta gamma TiAl-4Nb-3Mn alloy DO - 10.4028/www.scientific.net/MSF.706-709.1100 AU - Sawatzky, T. AU - Seo, D.Y. AU - Saari, H. AU - Laurin, D. AU - Kim, Y.-W. T2 - Materials Science Forum T3 - 7th International Conference on Processing and Manufacturing of Advanced Materials, THERMEC'2011, 1 August 2011 through 5 August 2011, Quebec City, QC SN - 0255-5476 SN - 9783037853030 VL - 706-709 SP - 1100 EP - 1105 KW - Aging heat treatment KW - Aging time KW - Beta-phase KW - Colony boundary KW - Colony size KW - Constant loads KW - Creep properties KW - Fine microstructure KW - Fully lamellar KW - Gamma-titanium aluminide KW - Hardness test KW - Hardness values KW - Heat treatment conditions KW - Interfacial precipitation KW - Lamellar interfaces KW - Lamellar spacing KW - Microstructural features KW - Nominal composition KW - Room temperature KW - Tensile creep KW - Titanium aluminide KW - Titanium aluminides KW - Cerium alloys KW - Creep KW - Grain growth KW - Hardness KW - Hot isostatic pressing KW - Manganese KW - Microstructural evolution KW - Niobium KW - Phase interfaces KW - Powder metallurgy KW - Sintering KW - Titanium KW - Titanium alloys KW - Titanium compounds KW - Creep resistance KW - Heat treatment AB - Pre-alloyed beta gamma titanium aluminide powder with a nominal composition of TiAl-4Nb-3Mn is consolidated by hot isostatic pressing. After consolidation, a step cooled heat treatment is performed to homogenize the material and produce a fully lamellar microstructure. Various aging heat treatments are then performed with the goal of forming interfacial beta phase precipitates along lamellar interfaces. The step cooled heat treatment produces a relatively fine microstructure with a lamellar spacing of 0.04 μm and an average lamellar colony size of 60 μm. The aging heat treatments generate beta phase precipitates along lamellar colony boundaries but not along lamellar interfaces, and result in lamellar degredation and grain growth. Constant load tensile creep and room temperature hardness tests are performed on step cooled heat treated and step cooled heat treated and aged specimens. Creep resistance, generally, improves with aging time, even with no interfacial precipitation, and the lamellar degredation that occurs with aging. The microstructures of the as-tested specimens are characterized and related to the creep properties. The hardness values are also compared as a function of selected heat treatment condition and microstructural features. © 2012 Trans Tech Publications, Switzerland. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1e31a2da-27d0-44f4-901d-f98930818bb0 ER - TY - JOUR TI - Mechanical properties of HSLA-65 hybrid laser arc welds DO - 10.1179/1879139512Y.0000000026 AU - Nolting, A.E. AU - Munro, C. AU - Cao, X.J. AU - Wanjara, P. T2 - Canadian Metallurgical Quarterly SN - 0008-4433 VL - 51 IS - 3 SP - 336 EP - 345 KW - Charpy specimen KW - HSLA steel KW - Hybrid laser arc welding KW - Single pass KW - Weld strength KW - Alloy steel KW - Electric welding KW - Fracture KW - High strength alloys KW - High strength steel KW - Mechanical properties KW - Shipbuilding KW - Shipyards KW - Tensile strength KW - Tensile testing KW - Heat affected zone AB - High strength steels are finding increasing use in the shipbuilding industry to decrease the weight of vessels for improved maneouverability and fuel efficiency, increased payloads and decreased fabrication costs. High strength low alloy (HSLA) steel, such as HSLA-65, provides a unique combination of strength, weldability and toughness that makes it a particularly attractive choice for many shipbuilding applications. However, as HSLA-65 is a thermomechanically processed steel, it can be susceptible to grain coarsening and softening in the heat affected zone (HAZ) during welding. Low heat input welding procedures such as hybrid laser arc welding are desirable because they minimise HAZ softening and can tolerate gaps between the workpieces better than conventional laser welding. In this paper, the mechanical properties of hybrid laser arc welds, used to join 9?1 mm thick HSLA-65 plates in a single pass, were evaluated. Hardness maps indicated that softening did not occur in the HAZ. Transverse tensile fracture occurred in the base metal, away from the welds, confirming that the fusion zone and HAZ had higher strength than the base metal. Subsized Charpy impact toughness specimens, notched in the HAZ, were typically less tough than the base metal. However, the fracture path typically deviated away from the HAZ, into either the base metal or along the fusion line. © 2012 Crown in Right of Canada. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1a954f70-554b-439e-8ab5-facaac9f8048 ER - TY - JOUR TI - A substellar companion to the dusty Pleiades star HD23514 DO - 10.1088/0004-637X/748/1/30 AU - Rodriguez, D.R. AU - Marois, C. AU - Zuckerman, B. AU - MacIntosh, B. AU - Melis, C. T2 - The Astrophysical Journal SN - 0004-637X VL - 748 IS - 1 SP - 30 AB - With adaptive optics imaging at Keck observatory, we have discovered a substellar companion to the F6 Pleiades star HD23514, one of the dustiest main-sequence stars known to date (L IR/L * 2%). This is one of the first brown dwarfs discovered as a companion to a star in the Pleiades. The 0.06 M ⊙ late-M secondary has a projected separation of 360AU. The scarcity of substellar companions to stellar primaries in the Pleiades combined with the extremely dusty environment make this a unique system to study. © 2012 The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5ec53a7a-28dc-4d5f-8e52-7f1a2371bb47 ER - TY - JOUR TI - Temperature changes during deformation of polycrystalline and nanocrystalline nickel DO - 10.4028/www.scientific.net/AMR.409.480 AU - Chan, T. AU - Backman, D. AU - Bos, R. AU - Sears, T. AU - Brooks, I. AU - Erb, U. T2 - Advanced Materials Research T3 - 7th International Conference on Processing and Manufacturing of Advanced Materials, THERMEC'2011, 1 August 2011 through 5 August 2011, Quebec City, QC SN - 1022-6680 SN - 9783037853047 VL - 409 SP - 480 EP - 485 KW - Grain size KW - Heat zone KW - High resolution KW - Maximum temperature KW - Nano-crystalline nickel KW - Nanocrystallines KW - Onset temperature KW - Polycrystalline KW - Room temperature KW - Stress-induced KW - Temperature changes KW - True stress-strain KW - Deformation KW - Grain size and shape KW - Heat generation KW - Nanocrystalline materials KW - Nickel KW - Polycrystalline materials KW - Strain rate KW - Stress-strain curves KW - Grain growth AB - Commercially available polycrystalline nickel (grain size: 30 μm) and electrodeposited nanocrystalline nickel (grain size: 30 nm) were analyzed for the effect of stress-induced heat generation during plastic deformation at room temperature. Tensile coupons in conformance to ASTM E8 standard were tested at a strain rate of 10 -1/s to record the amount heat dissipated using a high resolution infrared detector. The maximum temperature increases recorded for nanocrystalline and polycrystalline nickel close to sample fracture were 58° and 70°, respectively. Grain growth in nanocrystalline nickel due to stress-induced heat generation is unlikely since the maximum temperature during deformation is below the previously reported onset temperature for grain growth in nanocrystalline nickel. © (2012) Trans Tech Publications, Switzerland. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 631afc62-94e3-4efa-a2b7-8b07dc85560d ER - TY - JOUR TI - Human amniotic fluid cells form functional gap junctions with cortical cells DO - 10.1155/2012/607161 AU - Jezierski, A. AU - Rennie, K. AU - Tremblay, R. AU - Zurakowski, B. AU - Gruslin, A. AU - Sikorska, M. AU - Bani-Yaghoub, M. T2 - Stem Cells International SN - 1687-9678 SP - 607161 KW - connexin 43 KW - amniotic fluid cell KW - animal cell KW - animal experiment KW - animal model KW - article KW - astrocyte KW - brain injury KW - cell communication KW - cell culture KW - controlled study KW - female KW - gap junction KW - human KW - human cell KW - in vitro study KW - in vivo study KW - motor cortex KW - mouse KW - nonhuman KW - priority journal KW - protein expression AB - The usage of stem cells is a promising strategy for the repair of damaged tissue in the injured brain. Recently, amniotic fluid (AF) cells have received a lot of attention as an alternative source of stem cells for cell-based therapies. However, the success of this approach relies significantly on proper interactions between graft and host tissue. In particular, the reestablishment of functional brain networks requires formation of gap junctions, as a key step to provide sufficient intercellular communication. In this study, we show that AF cells express high levels of CX43 (GJA1) and are able to establish functional gap junctions with cortical cultures. Furthermore, we report an induction of Cx43 expression in astrocytes following injury to the mouse motor cortex and demonstrate for the first time CX43 expression at the interface between implanted AF cells and host brain cells. These findings suggest that CX43-mediated intercellular communication between AF cells and cortical astrocytes may contribute to the reconstruction of damaged tissue by mediating modulatory, homeostatic, and protective factors in the injured brain and hence warrants further investigation. © 2012 Anna Jezierski et al. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b58acce4-ee2a-40cd-a84f-11b4538fcce6 ER - TY - JOUR TI - Soil characteristics more strongly influence soil bacterial communities than land-use type DO - 10.1111/j.1574-6941.2011.01192.x AU - Kuramae, E.E. AU - Yergeau, E. AU - Wong, L.C. AU - Pijl, A.S. AU - Van Veen, J.A. AU - Kowalchuk, G.A. T2 - FEMS Microbiology Ecology SN - 0168-6496 VL - 79 IS - 1 SP - 12 EP - 24 KW - bacterial DNA KW - RNA 16S KW - abundance KW - electrokinesis KW - land use change KW - microbial community KW - pH KW - phosphate KW - phylogenetics KW - polymerase chain reaction KW - real time KW - soil carbon KW - soil microorganism KW - soil nitrogen KW - Alphaproteobacteria KW - article KW - bacterium KW - biodiversity KW - chemistry KW - classification KW - denaturing gradient gel electrophoresis KW - DNA sequence KW - Gammaproteobacteria KW - genetics KW - growth, development and aging KW - microbiology KW - Netherlands KW - phylogeny KW - real time polymerase chain reaction KW - soil KW - Alphaproteobacteria KW - Bacteria KW - Biodiversity KW - Denaturing Gradient Gel Electrophoresis KW - DNA, Bacterial KW - Gammaproteobacteria KW - Netherlands KW - Phylogeny KW - Real-Time Polymerase Chain Reaction KW - RNA, Ribosomal, 16S KW - Sequence Analysis, DNA KW - Soil KW - Soil Microbiology AB - To gain insight into the factors driving the structure of bacterial communities in soil, we applied real-time PCR, PCR-denaturing gradient gel electrophoreses, and phylogenetic microarray approaches targeting the 16S rRNA gene across a range of different land usages in the Netherlands. We observed that the main differences in the bacterial communities were not related to land-use type, but rather to soil factors. An exception was the bacterial community of pine forest soils (PFS), which was clearly different from all other sites. PFS had lowest bacterial abundance, lowest numbers of operational taxonomic units (OTUs), lowest soil pH, and highest C N ratios. C N ratio strongly influenced bacterial community structure and was the main factor separating PFS from other fields. For the sites other than PFS, phosphate was the most important factor explaining the differences in bacterial communities across fields. Firmicutes were the most dominant group in almost all fields, except in PFS and deciduous forest soils (DFS). In PFS, Alphaproteobacteria was most represented, while in DFS, Firmicutes and Gammaproteobacteria were both highly represented. Interestingly, Bacillii and Clostridium OTUs correlated with pH and phosphate, which might explain their high abundance across many of the Dutch soils. Numerous bacterial groups were highly correlated with specific soil factors, suggesting that they might be useful as indicators of soil status. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved 79 1 January 2012 10.1111/j.1574-6941.2011.01192.x Research Article Research Articles © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c7950bdf-d9c6-4fb6-8afe-d2aae7446ee2 ER - TY - JOUR TI - Neutral-ionic state correlations in strong-field molecular ionization DO - 10.1103/PhysRevLett.109.203007 AU - Kotur, M. AU - Zhou, C. AU - Matsika, S. AU - Patchkovskii, S. AU - Spanner, M. AU - Weinacht, T.C. T2 - Physical Review Letters SN - 0031-9007 VL - 109 IS - 20 SP - 203007 KW - Ammosov-Delone-Krainov KW - Bound electrons KW - Continuum electrons KW - Continuum state KW - Dyson orbital KW - Electronic transition KW - Ionic state KW - Ionization events KW - Molecular cations KW - Molecular ionization KW - Quasi-static KW - Semiclassical tunneling KW - Strong field ionization KW - Forecasting KW - Molecular orbitals KW - Ionization AB - We study correlations between neutral and ionic states in strong-field molecular ionization. We compare predictions based on Dyson orbital norms and quasistatic semiclassical tunneling theories (Keldysh and molecular orbital Ammosov-Delone-Krainov) with more detailed calculations of strong-field ionization which take into account (i)the Coulomb interaction between the outgoing continuum electron wave packet and the remaining bound electrons and (ii)electron-core interactions that cause distortions of the electronic continuum states during the ionization event. Our results highlight the prominence of electronic rearrangement effects in strong-field ionization with intense ultrafast laser pulses, where the outgoing continuum electron can cause electronic transitions in the parent ion. Calculations and measurements for excited uracil molecules reveal the breakdown of Keldysh-weighted Dyson norm predictions for ionization to different states of the molecular cation in the strong-field regime. © 2012 American Physical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a1478a5e-c179-4314-90f6-9bc0ce6f8283 ER - TY - JOUR TI - CORS Baade-Wesselink distance to the LMC NGC 1866 blue populous cluster DO - 10.1088/0004-637X/748/1/69 AU - Molinaro, R. AU - Ripepi, V. AU - Marconi, M. AU - Musella, I. AU - Brocato, E. AU - Mucciarelli, A. AU - Stetson, P.B. AU - Storm, J. AU - Walker, A.R. T2 - The Astrophysical Journal SN - 0004-637X VL - 748 IS - 1 SP - 69 AB - We used optical, near-infrared photometry, and radial velocity data for a sample of 11 Cepheids belonging to the young LMC blue populous cluster NGC 1866 to estimate their radii and distances on the basis of the CORS Baade-Wesselink method. This technique, based on an accurate calibration of surface brightness as a function of (U - B), (V - K) colors, allows us to estimate, simultaneously, the linear radius and the angular diameter of Cepheid variables, and consequently to derive their distance. A rigorous error estimate on radii and distances was derived by using Monte Carlo simulations. Our analysis gives a distance modulus for NGC 1866 of 18.51 ± 0.03mag, which is in agreement with several independent results. © 2012 The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fa89ed4b-1ab1-48e1-881a-796fbf21e6c2 ER - TY - JOUR TI - Colorless directional coupler with dispersion engineered sub-wavelength structure DO - 10.1364/OE.20.013470 AU - Halir, R. AU - Maese-Novo, A. AU - Ortega-Monux, A. AU - Molina-Fernández, I. AU - Wangüemert-Pérez, J.G. AU - Cheben, P. AU - Xu, D.-X. AU - Schmid, J.H. AU - Janz, S. T2 - Optics Express SN - 1094-4087 VL - 20 IS - 12 SP - 13470 EP - 13477 KW - 3D FDTD KW - Dispersive properties KW - Operation bandwidth KW - Phase response KW - Silicon-on-insulators KW - Sub-wave length grating KW - Sub-wavelength structures KW - Wavelength ranges KW - Diffraction gratings KW - Dispersion (waves) KW - Optical waveguides KW - Three dimensional computer graphics KW - Directional couplers AB - Directional couplers are extensively used devices in integrated optics, but suffer from limited operational wavelength range. Here we use, for the first time, the dispersive properties of sub-wavelength gratings to achieve a fivefold enhancement in the operation bandwidth of a silicon-oninsulator directional coupler. This approach does not compromise the size or the phase response of the device. The sub-wavelength grating based directional coupler we propose covers a 100nm bandwidth with an imbalance of =0.6dB between its outputs, as supported by full 3D FDTD simulations. © 2012 Optical Society of America. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1d548ffc-1e82-458b-8efd-045dab7b0432 ER - TY - JOUR TI - A thorough investigation of the distance to the supernova remnant CTB109 and its pulsar AXP J2301+5852 DO - 10.1088/2041-8205/746/1/L4 AU - Kothes, R. AU - Foster, T. T2 - The Astrophysical Journal Letters SN - 2041-8205 VL - 746 IS - 1 SP - L4 AB - CTB109 is one of only three Galactic supernova remnants (SNRs) known to harbor an anomalous X-ray pulsar or magnetar. That makes this SNR an object of great importance and a prime target for high-energy astrophysics studies. Those studies rely heavily on the assumed distance to CTB109. There have been three major distance determinations over the last decade, all of which report completely different results. While chaotic distance determinations in the literature are not uncommon for SNRs as a class of object, the wild discrepancy in the distance to CTB109 makes it especially important to revisit and firmly resolve once and for all. In this Letter we bring to bear all available observational information and present a synthesis of evidence that consistently locates CTB109 within or close to the Perseus arm spiral shock, at a distance of 3.2±0.2kpc. © 2012. National Research Council Canada. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 82ba43be-9579-47f0-835b-d8b023aa1f09 ER - TY - JOUR TI - Poly(ethylene glycol) as a compatibilizer and plasticizer of poly(lactic acid)/clay nanocomposites DO - 10.1177/0954008311433605 AU - Rodríguez-Llamazares, S. AU - Rivas, B.L. AU - Pérez, M. AU - Perrin-Sarazin, F. T2 - High Performance Polymers SN - 0954-0083 VL - 24 IS - 4 SP - 254 EP - 261 KW - Ammonium cations KW - Cloisite KW - Crystallization temperature KW - Melt-blending methods KW - Poly lactic acid KW - SEM and TEM KW - Silicate layers KW - Structure and thermal properties KW - Transmission electron microscopy tem KW - XRD KW - Ammonium compounds KW - Lactic acid KW - Nanocomposites KW - Organoclay KW - Plasticizers KW - Polypropylenes KW - Reinforced plastics KW - Scanning electron microscopy KW - Silicates KW - Thermogravimetric analysis KW - Transmission electron microscopy KW - X ray diffraction KW - Polyethylene glycols AB - Nanocomposites of poly(lactic acid), PLA, and poly(lactic acid)/poly(ethylene glycol), PLA/PEG, with clay modified with methyl-bis(2-hydroxyethyl) tallow alkyl ammonium cations (Cloisite 30B) were prepared by melt-blending methods. The influence of PEG content on the structure and thermal properties of nanocomposites was investigated. Comparative samples of the PLA/PEG blends with different PEG content were also considered. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC) were used to characterize the studied samples. From XRD, SEM and TEM results, it can be concluded that PEG molecules co-intercalate the silicate layers of Cloisite 30B, together with PLA, allowing better parallel stacking of the silicate layers and the interaction between them. The decrease in the glass transition temperature and crystallization temperature of PLA nanocomposites with an increase in the PEG content, showed the double role of PEG as a plasticizer and as a compatibilizer during the preparation of PLA nanocomposites. © The Author(s) 2012. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 15279187-62f2-4ac0-a88d-98bbe2dce135 ER - TY - JOUR TI - Ex vivo perfusion of the swine heart as a method for pre-transplant assessment DO - 10.1177/0267659112449035 AU - Colah, S. AU - Freed, D.H. AU - Mundt, P. AU - Germscheid, S. AU - White, P. AU - Ali, A. AU - Tian, G. AU - Large, S. AU - Falter, F. T2 - Perfusion (United Kingdom) SN - 0267-6591 VL - 27 IS - 5 SP - 408 EP - 413 KW - electrolyte KW - animal tissue KW - article KW - blood gas KW - brain stem KW - cost effectiveness analysis KW - ex vivo study KW - heart function KW - heart preload KW - heart transplantation KW - heart ventricle pressure KW - hematocrit KW - nonhuman KW - organ donor KW - organ perfusion KW - preoperative evaluation KW - priority journal KW - reperfusion KW - swine KW - systolic blood pressure KW - Animals KW - Extracorporeal Circulation KW - Heart KW - Heart Transplantation KW - Myocardial Reperfusion KW - Myocardial Reperfusion Injury KW - Organ Preservation KW - Perfusion KW - Risk Assessment KW - Swine KW - Tissue Donors AB - We describe a cost-effective, reproducible circuit in a porcine, ex vivo, continuous warm-blood, bi-ventricular, working heart model that has future possibilities for pre-transplant assessment of marginal hearts donated from brain stem dead donors and hearts donated after circulatory determination of death (DCDD).In five consecutive experiments over five days, pressure volume loops were performed. During working mode, the left ventricular end systolic pressure volume relationship (LV ESPVR) was 23.1±11.1 mmHg/ml and the LV preload recruitable stroke work (PRSW) was 67.8±7.2. (Standard PVAN analysis software) (Millar Instruments, Houston, TX, USA)All five hearts were perfused for 219±64 minutes and regained normal cardiac function on the perfusion system.They displayed a significant upward and leftward shift of the end systolic pressure volume relationship, a significant increase in preload recruitable stroke work and minimal stiffness. These hearts could potentially be considered for transplantation. The circuit was effective during reperfusion and working modes whilst proving to be successful in maintaining cardiac function in excess of four hours. Using an autologous prime of approximately 20% haematocrit (Hct), electrolytes and blood gases were easy to control within this period using standard perfusion techniques. © The Author(s) 2012. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 64fd5ce1-56c9-4c5d-b15d-d971e27aeda9 ER - TY - JOUR TI - Hypochlorite treatment of polyamide membrane for improved reverse osmosis performance DO - 10.12989/mwt.2013.4.1.069 AU - Shao, P. AU - Kurth, C.J. T2 - Membrane Water Treatment SN - 2005-8624 VL - 4 IS - 1 SP - 69 EP - 81 KW - Chlorinating species KW - Hypochlorite treatment KW - Membrane chemistry KW - N-chlorination KW - Salt rejections KW - Alkalinity KW - Chlorination KW - Chlorine KW - Hydrolysis KW - pH KW - Polyamides KW - Reverse osmosis KW - Membranes AB - The pH-dependent inter-conversion of the three free chlorine species (Cl2, HOCl, OCl-) present in the aqueous hypochlorite solution was theoretically investigated. Each species was found overwhelmingly present in a characteristic pH range. Hypochlorite treatment of the polyamide membrane was carried out over these pH ranges and various membrane responses were observed. As pH is less than 8, membrane tends to be N-chlorinated by Cl2 and HOCl, and N-chlorinated membrane showed reduced water permeance and salt rejection. As pH rises to 10-12, OCl appears to be the dominating chlorine species. Membrane hydrolysis was found to well interpret the improved water permeance and salt rejection. When the pH is between 8-10, both N-chlorination and hydrolysis contribute to the response of the membrane, and the treated membrane showed improved salt rejection but reduced water permeation. Excessive hydrolysis occurred while the membrane was treated at pH 13 for the much stronger alkalinity. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bbf27c9f-434e-4030-b494-e415882e46a4 ER - TY - JOUR TI - On the shapes and structures of high-redshift compact galaxies DO - 10.1088/2041-8205/754/2/L24 AU - Chevance, M. AU - Weijmans, A.-M. AU - Damjanov, I. AU - Abraham, R.G. AU - Simard, L. AU - Van Den Bergh, S. AU - Caris, E. AU - Glazebrook, K. T2 - The Astrophysical Journal Letters SN - 2041-8205 VL - 754 IS - 2 SP - L24 AB - Recent deep Hubble Space Telescope WFC3 imaging suggests that a majority of compact quiescent massive galaxies at z 2 may contain disks. To investigate this claim, we have compared the ellipticity distribution of 31 carefully selected high-redshift massive quiescent compact galaxies to a set of mass-selected ellipticity and Sérsic index distributions obtained from two-dimensional structural fits to 40, 000 nearby galaxies from the Sloan Digital Sky Survey. A Kolmogorov-Smirnov test shows that the distribution of ellipticities for the high-redshift galaxies is consistent with the ellipticity distribution of a similarly chosen sample of massive early-type galaxies. However, the distribution of Sérsic indices for the high-redshift sample is inconsistent with that of local early-type galaxies, and instead resembles that of local disk-dominated populations. The mismatch between the properties of high-redshift compact galaxies and those of both local early-type and disk-dominated systems leads us to conclude that the basic structures of high-redshift compact galaxies probably do not closely resemble those of any single local galaxy population. Any galaxy population analog to the high-redshift compact galaxies that exists at the current epoch is either a mix of different types of galaxies, or possibly a unique class of objects on their own. © 2012. The American Astronomical Society. All rights reserved.. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a09f075b-b542-4b5e-b502-be5dd3439b8b ER - TY - JOUR TI - Surface brightness fluctuations as primary and secondary distance indicators DO - 10.1007/s10509-012-0997-6 AU - Blakeslee, J.P. T2 - Astrophysics and Space Science SN - 0004-640X VL - 341 IS - 1 SP - 179 EP - 186 AB - The surface brightness fluctuations (SBF) method measures the variance in a galaxy's light distribution arising from fluctuations in the numbers and luminosities of individual stars per resolution element. Once calibrated for stellar population effects, SBF measurements with HST provide distances to early-type galaxies with unrivaled precision. Optical SBF data from HST for the Virgo and Fornax clusters give the relative distances of these nearby fiducial clusters with 2% precision and constrain their internal structures. Observations in hand will allow us to tie the Coma cluster, the standard of comparison for distant cluster studies, into the same precise relative distance scale. The SBF method can be calibrated in an absolute sense either empirically from Cepheids or theoretically from stellar population models. The agreement between the model and empirical zero points has improved dramatically, providing an independent confirmation of the Cepheid distance scale. SBF is still brighter in the near-IR, and an ongoing program to calibrate the method for the F110W and F160W passbands of the Wide Field Camera 3 IR channel will enable accurate distance derivation whenever a large early-type galaxy or bulge is observed in these passbands at distances reaching well out into the Hubble flow. © 2012 UK Crown: National Research Council of Canada. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : aa94b0e4-f032-45a8-95cb-37b7b2c60fd0 ER - TY - JOUR TI - Modulation of toxin production by the flagellar regulon in Clostridium difficile DO - 10.1128/IAI.00224-12 AU - Aubry, A. AU - Hussack, G. AU - Chen, W. AU - KuoLee, R. AU - Twine, S.M. AU - Fulton, K.M. AU - Foote, S. AU - Carrillo, C.D. AU - Tanha, J. AU - Logan, S.M. T2 - Infection and Immunity SN - 0019-9567 VL - 80 IS - 10 SP - 3521 EP - 3532 KW - bacterial protein KW - CD0240 protein KW - flhB protein KW - fliC protein KW - fliF protein KW - fliM protein KW - fliR protein KW - mutant protein KW - unclassified drug KW - animal experiment KW - animal model KW - article KW - bacterial genetics KW - bacterial virulence KW - Clostridium difficile KW - controlled study KW - cytotoxicity KW - female KW - flagellum KW - gene expression KW - gene inactivation KW - gene locus KW - gene regulatory network KW - genetic transcription KW - immunoassay KW - immunoblotting KW - nonhuman KW - priority journal KW - protein secretion KW - proteomics KW - regulon KW - supernatant KW - toxin synthesis KW - Animals KW - Bacterial Proteins KW - Bacterial Toxins KW - Clostridium difficile KW - Cricetinae KW - Enzyme-Linked Immunosorbent Assay KW - Female KW - Flagella KW - Gene Expression Regulation, Bacterial KW - Mutation KW - Proteomics KW - RNA, Bacterial KW - Sigma Factor KW - Transcriptome AB - We show in this study that toxin production in Clostridium difficile is altered in cells which can no longer form flagellar filaments. The impact of inactivation of fliC, CD0240, fliF, fliG, fliM, and flhB-fliR flagellar genes upon toxin levels in culture supernatants was assessed using cell-based cytotoxicity assay, proteomics, immunoassay, and immunoblotting approaches. Each of these showed that toxin levels in supernatants were significantly increased in a fliC mutant compared to that in the C. difficile 630 parent strain. In contrast, the toxin levels in supernatants secreted from other flagellar mutants were significantly reduced compared with that in the parental C. difficile 630 strain. Transcriptional analysis of the pathogenicity locus genes (tcdR, tcdB, tcdE, and tcdA) revealed a significant increase of all four genes in the fliC mutant strain, while transcription of all four genes was significantly reduced in fliM, fliF, fliG, and flhB-fliR mutants. These results demonstrate that toxin transcription in C. difficile is modulated by the flagellar regulon. More significantly, mutant strains showed a corresponding change in virulence compared to the 630 parent strain when tested in a hamster model of C. difficile infection. This is the first demonstration of differential flagellum-related transcriptional regulation of toxin production in C. difficile and provides evidence for elaborate regulatory networks for virulence genes in C. difficile. © 2012, American Society for Microbiology. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 211e9e90-c722-49aa-a9e7-58ebfe9fe2f2 ER - TY - JOUR TI - Abcg2 deficiency augments oxidative stress and cognitive deficits in Tg-SwDI transgenic mice DO - 10.1111/j.1471-4159.2012.07783.x AU - Zeng, Y. AU - Callaghan, D. AU - Xiong, H. AU - Yang, Z. AU - Huang, P. AU - Zhang, W. T2 - Journal of Neurochemistry SN - 0022-3042 VL - 122 IS - 2 SP - 456 EP - 469 KW - beta actin KW - breast cancer resistance protein KW - cytokine KW - DNA KW - glutathione KW - intercellular adhesion molecule 1 KW - interleukin 1beta KW - lipid KW - monocyte chemotactic protein 5 KW - transcription factor Nrf2 KW - animal experiment KW - animal model KW - animal tissue KW - article KW - brain tissue KW - cognitive defect KW - controlled study KW - developmental stage KW - enzyme linked immunosorbent assay KW - female KW - gel mobility shift assay KW - gene expression KW - genotype KW - inflammation KW - lipid oxidation KW - male KW - memory disorder KW - mouse KW - nonhuman KW - oxidative stress KW - priority journal KW - protein deficiency KW - protein expression KW - real time polymerase chain reaction KW - transgenic mouse KW - Western blotting KW - Aging KW - Amyloid beta-Peptides KW - Animals KW - ATP-Binding Cassette Transporters KW - Cognition Disorders KW - Cytokines KW - Disease Progression KW - DNA KW - Encephalitis KW - Enzyme-Linked Immunosorbent Assay KW - Glutathione KW - Heme Oxygenase-1 KW - Immunohistochemistry KW - Intercellular Adhesion Molecule-1 KW - Maze Learning KW - Mice KW - Mice, Knockout KW - Mice, Transgenic KW - NF-E2-Related Factor 2 KW - Oxidative Stress KW - Peptide Fragments KW - Real-Time Polymerase Chain Reaction KW - Signal Transduction KW - Mus KW - Mus musculus AB - Oxidative stress and neuroinflammation play important roles in Alzheimer's disease (AD). ABCG2 is a transporter protein expressed in the brain and involved in GSH transport. To study the roles of Abcg2 in oxidative stress and AD, we cross-bred Tg-SwDI and Abcg2-KO mice and generated Tg-SwDI/Abcg2-KO (double-tg) mice. Brain tissues from double-tg, Tg-SwDI, wild-type, and Abcg2-KO mice at various ages were analyzed. Aβ40 and Aβ42 were detected in Tg-SwDI and double-tg mice. Total brain GSH was decreased and levels of lipid/DNA oxidation were increased in 3-month double-tg compared to Tg-SwDI mice. Low brain GSH was still detected in 9-month double-tg mice. Increased HMOX-1 and MCP-5 expression was observed in 9-month double-tg mice but not in Tg-SwDI mice compared to WT and Abcg2-KO mice. Increased HMOX-1 and decreased ICAM-1 expression were observed in 12-month double-tg mice compared to Tg-SwDI mice. The levels of Nrf-2 expression and activity were decreased in 6-month double-tg mice. Behavioral tests show impaired cognitive/memory performance of 9-month double-tg compared to Tg-SwDI mice as well as WT and Abcg2-KO mice. These results suggest that Abcg2 deficiency increases oxidative stress and alters inflammatory response in the brain and exacerbates cognitive/memory deficit in double-tg mice at different developmental stages. © 2012 National Research Council Canada & The Authors. Journal of Neurochemistry © 2012 International Society for Neurochemistry. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : dabadeb2-d677-402a-9cbe-a0cc2911c4bd ER - TY - CHAP TI - Natural Polymers with Antioxidant Properties: Poly-/oligosaccharides of Marine Origin DO - 10.1002/9781118445440.ch8 AU - Jiao, G. AU - Yu, G. AU - Zhao, X. AU - Zhang, J. AU - Ewart, H.S. T2 - Antioxidant Polymers: Synthesis, Properties, and Applications SN - 9781118208540 SP - 179 EP - 201 AB - In recent decades, poly- and oligosaccharides derived from marine sources including algae, invertebrates and some bacteria display significant antioxidant activities. Development of therapeutic products based on such bioactive poly-/oligosaccharides has been generating considerable interest. Research has shown that the antioxidant properties of marine polysaccharides depend on a number of structural properties, such as the functional groups, molecular weight, and monosaccharide compositions. Structural characteristics may lead to differing mechanisms responsible for antioxidant activities that can be evaluated by various in vitro approaches including l,l-diphenyl-2-picrylhydrazil radical scavenging, ferric reducing antioxidant power, Superoxide radical and hydroxyl radical scavenging assays. This chapter reviews the research on the antioxidant properties of marine poly- and oligosaccharides, with particular emphasis on the relationship between their structural features and antioxidant mechanism. The antioxidant properties of marine poly- and oligosaccharides may lead to their increased use as natural antioxidant agents in food, medical, cosmetic, and other applications. © 2012 Scrivener Publishing LLC. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 772a1f14-635f-40ea-abb7-3d186575f902 ER - TY - JOUR TI - Supernova 2008bk and its red supergiant progenitor DO - 10.1088/0004-6256/143/1/19 AU - Van Dyk, S.D. AU - Davidge, T.J. AU - Elias-Rosa, N. AU - Taubenberger, S. AU - Li, W. AU - Levesque, E.M. AU - Howerton, S. AU - Pignata, G. AU - Morrell, N. AU - Hamuy, M. AU - Filippenko, A.V. T2 - Astronomical Journal SN - 0004-6256 VL - 143 IS - 1 SP - 19 AB - We have obtained limited photometric and spectroscopic data for supernova (SN) 2008bk in NGC7793, primarily at ≳ 150 days after explosion. We find that it is a Type II-Plateau (II-P) SN that most closely resembles the low-luminosity SN1999br in NGC4900. Given the overall similarity between the observed light curves and colors of SNe 2008bk and 1999br, we infer that the total visual extinction to SN2008bk (AV = 0.065mag) must be almost entirely due to the Galactic foreground, similar to what has been assumed for SN1999br. We confirm the identification of the putative red supergiant (RSG) progenitor star of the SN in high-quality g′r′i′ images we had obtained in 2007 at the Gemini-South 8m telescope. Little ambiguity exists in this progenitor identification, qualifying it as the best example to date, next to the identification of the star Sk -69°202 as the progenitor of SN1987A. From a combination of photometry of the Gemini images with that of archival, pre-SN, Very Large Telescope JHKs images, we derive an accurate observed spectral energy distribution (SED) for the progenitor. We find from nebular strong-intensity emission-line indices for several H II regions near the SN that the metallicity in the environment is likely subsolar (Z 0.6 Z ⊙). The observed SED of the star agrees quite well with synthetic SEDs obtained from model RSG atmospheres with effective temperature T eff = 3600 50K. We find, therefore, that the star had a bolometric luminosity with respect to the Sun of log (L bol/L ⊙) = 4.57 0.06 and radius R ⊙ = 496 34 R ⊙ at 6 months prior to explosion. Comparing the progenitor's properties with theoretical massive-star evolutionary models, we conclude that the RSG progenitor had an initial mass in the range of 8-8.5 M ⊙. This mass is consistent with, albeit at the low end of, the inferred range of initial masses for SN II-P progenitors. It is also consistent with the estimated upper limit on the initial mass of the progenitor of SN1999br, and it agrees with the low initial masses found for the RSG progenitors of other low-luminosity SNe II-P. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 93e7371c-c1d0-423d-9d90-f38563b2979a ER - TY - JOUR TI - MetaboAnalyst 2.0-a comprehensive server for metabolomic data analysis DO - 10.1093/nar/gks374 AU - Xia, J. AU - Mandal, R. AU - Sinelnikov, I.V. AU - Broadhurst, D. AU - Wishart, D.S. T2 - Nucleic Acids Research SN - 0305-1048 VL - 40 IS - W1 SP - W127 EP - W133 KW - article KW - computer KW - computer program KW - controlled study KW - data processing KW - functional enrichment analysis KW - image display KW - Internet KW - metabolism KW - metabolite KW - metabolomics KW - performance KW - priority journal KW - quality control KW - statistical analysis KW - time series analysis KW - web server KW - Classification KW - Cluster Analysis KW - Computer Graphics KW - Internet KW - Metabolomics KW - Software AB - First released in 2009, MetaboAnalyst (www.metaboanalyst.ca) was a relatively simple web server designed to facilitate metabolomic data processing and statistical analysis. With continuing advances in metabolomics along with constant user feedback, it became clear that a substantial upgrade to the original server was necessary. MetaboAnalyst 2.0, which is the successor to MetaboAnalyst, represents just such an upgrade. MetaboAnalyst 2.0 now contains dozens of new features and functions including new procedures for data filtering, data editing and data normalization. It also supports multi-group data analysis, two-factor analysis as well as time-series data analysis. These new functions have also been supplemented with: (i) a quality-control module that allows users to evaluate their data quality before conducting any analysis, (ii) a functional enrichment analysis module that allows users to identify biologically meaningful patterns using metabolite set enrichment analysis and (iii) a metabolic pathway analysis module that allows users to perform pathway analysis and visualization for 15 different model organisms. In developing MetaboAnalyst 2.0 we have also substantially improved its graphical presentation tools. All images are now generated using anti-aliasing and are available over a range of resolutions, sizes and formats (PNG, TIFF, PDF, PostScript, or SVG). To improve its performance, MetaboAnalyst 2.0 is now hosted on a much more powerful server with substantially modified code to take advantage the server's multi-core CPUs for computationally intensive tasks. MetaboAnalyst 2.0 also maintains a collection of 50 or more FAQs and more than a dozen tutorials compiled from user queries and requests. A downloadable version of MetaboAnalyst 2.0, along detailed instructions for local installation is now available as well. © 2012 The Author(s). DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1f0ff34b-f0fa-426c-a6be-f7df0f837ac4 ER - TY - JOUR TI - Plasma protein adsorption to zwitterionic poly (Carboxybetaine Methacrylate) modified surfaces: Chain chemistry and end-group effects on protein adsorption kinetics, adsorbed amounts and immunoblots DO - 10.1007/s13758-012-0040-z AU - Abraham, S. AU - Bahniuk, M.S. AU - Unsworth, L.D. T2 - Biointerphases SN - 1934-8630 VL - 7 IS - 1-Apr SP - 1 EP - 14 AB - Protein-surface interactions are crucial to the overall biocompatability of biomaterials, and are thought to be the impetus towards the adverse host responses such as blood coagulation and complement activation. Only a few studies hint at the ultra-low fouling potential of zwitterionic poly(carboxybetaine methacrylate) (PCBMA) grafted surfaces and, of those, very few systematically investigate their non-fouling behavior. In this work, single protein adsorption studies as well as protein adsorption from complex solutions (i.e. human plasma) were used to evaluate the non-fouling potential of PCBMA grafted silica wafers prepared by nitroxide- mediated free radical polymerization. PCBMAs used for surface grafting varied in charge separating spacer groups that influence the overall surface charges, and chain endgroups that influence the overall hydrophilicity, thereby, allows a better understanding of these effects towards the protein adsorption for thesematerials. In situ ellipsometry was used to quantify the adsorbed layer thickness and adsorption kinetics for the adsorption of four proteins from single protein buffer solutions, viz, lysozyme, α-lactalbumin, human serum albumin and fibrinogen. Total amount of protein adsorbed on surfaces differed as a function of surface properties and protein characteristics. Finally, immunoblots results showed that human plasma protein adsorption to these surfaces resulted, primarily, in the adsorption of human serum albumin, with total protein adsorbed amounts being the lowest for PCBMA-3 (TEMPO). It was apparent that surface charge and chain hydrophilicity directly influenced protein adsorption behavior of PCBMA systems and are promising materials for biomedical applications. © The Author(s) 2012. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 31d410c9-6d32-46d2-8960-9ad1bfa6a5d4 ER - TY - JOUR TI - Enhancement in broadband and quasi-omnidirectional antireflection of nanopillar arrays by ion milling DO - 10.1088/0957-4484/23/27/275703 AU - Huang, Z. AU - Hawkeye, M.M. AU - Brett, M.J. T2 - Nanotechnology SN - 0957-4484 VL - 23 IS - 27 SP - 275703 KW - Angle of Incidence KW - Anti-reflection KW - Bottom-up fabrication KW - Crystallographic structure KW - Engineering process KW - Field of views KW - Glancing Angle Deposition KW - Impedance match KW - Integrated techniques KW - Ion milling KW - Mass redistribution KW - Nano-pillar arrays KW - Post-deposition KW - Reflection loss KW - Structure transformations KW - Tapered geometry KW - TiO KW - Topdown KW - Wavelength ranges KW - Antireflection coatings KW - Biomimetics KW - Competition KW - Ion bombardment KW - Refractive index KW - Stoichiometry KW - Titanium dioxide KW - Milling (machining) KW - ion KW - nanomaterial KW - article KW - chemistry KW - light KW - materials testing KW - methodology KW - particle size KW - radiation scattering KW - refractometry KW - surface plasmon resonance KW - surface property KW - ultrastructure KW - Ions KW - Light KW - Materials Testing KW - Nanostructures KW - Particle Size KW - Refractometry KW - Scattering, Radiation KW - Surface Plasmon Resonance KW - Surface Properties AB - A new technique is developed to fabricate biomimetic antireflection coatings (ARCs). This technique combines a bottom-up fabrication approach (glancing angle deposition, or GLAD) with a top-down engineering process (ion milling). The GLAD technique is first utilized to produce nanopillar arrays (NPAs) with broadened structures, which are subsequently transformed into biomimetic tapered geometries by means of post-deposition ion milling. This structure transformation, due to milling-induced mass redistribution, remarkably decreases reflection over a wide wavelength range (3001700nm) and field of view (angle of incidence <60°with respect to the substrate normal). The milling-induced antireflection enhancement has been demonstrated in the NPAs made of Si, SiO x and TiO 2, illustrating that this integrated technique is readily adapted to a wide variety of materials. Good agreement between simulation and experiment indicates that the enhanced antireflection performance is ascribed to a smoother refractive index transition from the substrate to the air, which improves the impedance match and reduces reflection losses. Additionally, ion bombardment tends to alter the stoichiometry and diminish the crystallographic structure of the NPA materials. The broadband and quasi-omnidirectional antireflection observed establishes the strong competitiveness of this technique with the methods previously reported. © 2012 IOP Publishing Ltd. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e3b091d1-174c-407a-9aab-6a638cb5291e ER - TY - JOUR TI - The JCMT Legacy Survey of the Gould Belt: Mapping 13CO and C 18O in Orion A DO - 10.1111/j.1365-2966.2012.20628.x AU - Buckle, J.V. AU - Davis, C.J. AU - di Francesco, J. AU - Graves, S.F. AU - Nutter, D. AU - Richer, J.S. AU - Roberts, J.F. AU - Ward-Thompson, D. AU - White, G.J. AU - Brunt, C. AU - Butner, H.M. AU - Cavanagh, B. AU - Chrysostomou, A. AU - Curtis, E.I. AU - Duarte-Cabral, A. AU - Etxaluze, M. AU - Fich, M. AU - Friberg, P. AU - Friesen, R. AU - Fuller, G.A. AU - Greaves, J.S. AU - Hatchell, J. AU - Hogerheijde, M.R. AU - Johnstone, D. AU - Matthews, B. AU - Matthews, H. AU - Rawlings, J.M.C. AU - Sadavoy, S. AU - Simpson, R.J. AU - Tothill, N.F.H. AU - Tsamis, Y.G. AU - Viti, S. AU - Wouterloot, J.G.A. AU - Yates, J. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 422 IS - 1 SP - 521 EP - 541 AB - The Gould Belt Legacy Survey will map star-forming regions within 500pc, using Heterodyne Array Receiver Programme (HARP), Submillimetre Common-User Bolometer Array 2 (SCUBA-2) and Polarimeter 2 (POL-2) on the James Clerk Maxwell Telescope (JCMT). This paper describes HARP observations of the J= 3 → 2 transitions of 13CO and C 18O towards Orion A. The 15arcsec resolution observations cover 5pc of the Orion filament, including OMC 1 (including BN-KL and Orion bar), OMC 2/3 and OMC 4, and allow a comparative study of the molecular gas properties throughout the star-forming cloud. The filament shows a velocity gradient of ∼1kms -1pc -1 between OMC 1, 2 and 3, and high-velocity emission is detected in both isotopologues. The Orion Nebula and Bar have the largest masses and linewidths, and dominate the mass and energetics of the high-velocity material. Compact, spatially resolved emission from CH 3CN, 13CH 3OH, SO, HCOOCH 3, CH 3CHO and CH 3OCHO is detected towards the Orion Hot Core. The cloud is warm, with a median excitation temperature of ∼24K; the Orion Bar has the highest excitation temperature gas, at >80K. The C 18O excitation temperature correlates well with the dust temperature (to within 40 per cent). The C 18O emission is optically thin, and the 13CO emission is marginally optically thick; despite its high mass, OMC 1 shows the lowest opacities. A virial analysis indicates that Orion A is too massive for thermal or turbulent support, but is consistent with a model of a filamentary cloud that is threaded by helical magnetic fields. The variation of physical conditions across the cloud is reflected in the physical characteristics of the dust cores. We find similar core properties between starless and protostellar cores, but variations in core properties with position in the filament. The OMC 1 cores have the highest velocity dispersions and masses, followed by OMC 2/3 and OMC 4. The differing fragmentation of these cores may explain why OMC 1 has formed clusters of high-mass stars, whereas OMC 4 produces fewer, predominantly low-mass stars. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cfa228b9-5e6d-47ad-a96c-89bd559b4fed ER - TY - JOUR TI - Relationship between low and high frequencies in δ scuti stars: Photometric kepler and spectroscopic analyses of the rapid rotator KIC8054146 DO - 10.1088/0004-637X/759/1/62 AU - Breger, M. AU - Fossati, L. AU - Balona, L. AU - Kurtz, D.W. AU - Robertson, P. AU - Bohlender, D. AU - Lenz, P. AU - Müller, I. AU - Lüftinger, Th. AU - Clarke, B.D. AU - Hall, J.R. AU - Ibrahim, K.A. T2 - The Astrophysical Journal SN - 0004-637X VL - 759 IS - 1 SP - 62 AB - Two years of Kepler data of KIC8054146 (δSct/γDor hybrid) revealed 349 statistically significant frequencies between 0.54 and 191.36cyclesday -1 (6.3μHz to 2.21mHz). The 117 low frequencies cluster in specific frequency bands, but do not show the equidistant period spacings predicted for gravity modes of successive radial order, n, and reported for at least one other hybrid pulsator. The four dominant low frequencies in the 2.8-3.0cyclesday -1 (32-35μHz) range show strong amplitude variability with timescales of months and years. These four low frequencies also determine the spacing of the higher frequencies in and beyond the δSct pressure-mode frequency domain. In fact, most of the higher frequencies belong to one of three families with spacings linked to a specific dominant low frequency. In the Fourier spectrum, these family regularities show up as triplets, high-frequency sequences with absolutely equidistant frequency spacings, side lobes (amplitude modulations), and other regularities in frequency spacings. Furthermore, within two families the amplitude variations between the low and high frequencies are related. We conclude that the low frequencies (gravity modes, rotation) and observed high frequencies (mostly pressure modes) are physically connected. This unusual behavior may be related to the very rapid rotation of the star: from a combination of high- and low-resolution spectroscopy we determined that KIC8054146 is a very fast rotator (υ sin i=300±20km s -1) with an effective temperature of 7600±200K and a surface gravity log g of 3.9±0.3. Several astrophysical ideas explaining the origin of the relationship between the low and high frequencies are explored. © 2012. The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b11bb3a0-72de-4495-9d1b-7bfe3e0c68f6 ER - TY - JOUR TI - Chapter 3: Small molecules and disease DO - 10.1371/journal.pcbi.1002805 AU - Wishart, D.S. T2 - PLoS Computational Biology SN - 1553-734X VL - 8 IS - 12 SP - e1002805 KW - article KW - bioinformatics KW - chemical bioinformatics KW - data analysis software KW - data mining KW - drug database KW - knowledge base KW - metabolomics KW - pharmacogenomics KW - systems biology KW - toxicogenetics KW - Biological Markers KW - Computational Biology KW - Databases, Factual KW - Disease KW - Drug Discovery KW - Humans KW - Metabolomics KW - User-Computer Interface AB - "Big" molecules such as proteins and genes still continue to capture the imagination of most biologists, biochemists and bioinformaticians. "Small" molecules, on the other hand, are the molecules that most biologists, biochemists and bioinformaticians prefer to ignore. However, it is becoming increasingly apparent that small molecules such as amino acids, lipids and sugars play a far more important role in all aspects of disease etiology and disease treatment than we realized. This particular chapter focuses on an emerging field of bioinformatics called "chemical bioinformatics" - a discipline that has evolved to help address the blended chemical and molecular biological needs of toxicogenomics, pharmacogenomics, metabolomics and systems biology. In the following pages we will cover several topics related to chemical bioinformatics. First, a brief overview of some of the most important or useful chemical bioinformatic resources will be given. Second, a more detailed overview will be given on those particular resources that allow researchers to connect small molecules to diseases. This section will focus on describing a number of recently developed databases or knowledgebases that explicitly relate small molecules - either as the treatment, symptom or cause - to disease. Finally a short discussion will be provided on newly emerging software tools that exploit these databases as a means to discover new biomarkers or even new treatments for disease. © 2012 David S. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c9479412-e647-40f5-acc0-ec493d9cb58d ER - TY - JOUR TI - VLBI for Gravity Probe B. V. Proper motion and parallax of the guide star, im Pegasi DO - 10.1088/0067-0049/201/1/5 AU - Ratner, M.I. AU - Bartel, N. AU - Bietenholz, M.F. AU - Lebach, D.E. AU - Lestrade, J.-F. AU - Ransom, R.R. AU - Shapiro, I.I. T2 - Astrophysical Journal, Supplement Series SN - 0067-0049 VL - 201 IS - 1 SP - 5 AB - We present the principal astrometric results of the very long baseline interferometry (VLBI) program undertaken in support of the Gravity Probe B (GP-B) relativity mission. VLBI observations of the GP-B guide star, the RS CVn binary IM Pegasi (HR 8703), yielded positions at 35 epochs between 1997 and 2005. We discuss the statistical assumptions behind these results and our methods for estimating the systematic errors. We find the proper motion of IM Peg in an extragalactic reference frame closely related to the International Celestial Reference Frame 2 (ICRF2) to be -20.83 ± 0.03 ± 0.09masyr -1 in right ascension and -27.27 ± 0.03 ± 0.09masyr -1 in declination. For each component, the first uncertainty is the statistical standard error and the second is the total standard error (SE) including plausible systematic errors. We also obtain a parallax of 10.37 ± 0.07mas (distance: 96.4 ± 0.7pc), for which there is no evidence of any significant contribution of systematic error. Our parameter estimates for the 25day period orbital motion of the stellar radio emission have SEs corresponding to 0.10mas on the sky in each coordinate. The total SE of our estimate of IM Peg's proper motion is 30% smaller than the accuracy goal set by the GP-B project before launch: 0.14masyr -1 for each coordinate of IM Peg's proper motion. Our results ensure that the uncertainty in IM Peg's proper motion makes only a very small contribution to the uncertainty of the GP-B relativity tests. © 2012. The American Astronomical Society. All rights reserved.. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f630f790-b520-4be6-9b54-00ec15d303d8 ER - TY - JOUR TI - Grinding characteristics of a nickel-based alloy using vitrified CBN wheels DO - 10.1504/IJAT.2012.046827 AU - Shi, Z. AU - Elfizy, A. AU - St-Pierre, B. AU - Attia, H. T2 - International Journal of Abrasive Technology SN - 1752-2641 VL - 5 IS - 1 SP - 1 EP - 16 KW - G-ratio KW - Grinding force KW - Grinding power KW - Nickel based alloy KW - Vitrified CBN KW - Grinding wheels KW - Iron alloys KW - Jet engines KW - Surface roughness KW - Vehicles KW - Wheel dressing KW - Grinding (machining) AB - An experimental study is reported on the grinding of a nickel-based alloy using vitrified CBN wheels. This work was motivated by switching the grinding of fir-tree root forms of jet engine blades from creep-feed grinding with conventional abrasive wheels to vitrified CBN wheels. The objective is to explore process limits and practical grinding parameters for judging the switch in terms of overall costs and productivity. Straight surface grinding experiments were conducted with water-based fluid on rectangular blocks at a fixed wheel speed ν s = 45 m/s, various depths of cut a = 0.05-1.0 mm, and workspeeds ν w = 2-40 mm/s. Grinding and dressing power, forces, surface roughness, and radial wheel wear were measured. Specific material removal rate of 8 mm 3/(mm.s) was reached in rough grinding using a wheel dressed for achieving surface roughness R a = 0.8 μm in finish grinding. It was found that shallow depths of cut combined with fast workspeeds, or less creep-feed modes, are more suitable for achieving high material removal rates with vitrified CBN grinding. Rough grinding is restricted by high grinding temperatures with newly dressed wheels and by chatters with worn wheels. Copyright © 2012 Inderscience Enterprises Ltd. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 783df4bd-3684-458b-9853-2e2d4c11ece2 ER - TY - JOUR TI - The recent stellar archeology of M31 - The nearest red disk galaxy DO - 10.1088/0004-637X/751/1/74 AU - Davidge, T.J. AU - McConnachie, A.W. AU - Fardal, M.A. AU - Fliri, J. AU - Valls-Gabaud, D. AU - Chapman, S.C. AU - Lewis, G.F. AU - Rich, R.M. T2 - The Astrophysical Journal SN - 0004-637X VL - 751 IS - 1 SP - 74 AB - We examine the star-forming history of the M31 disk during the past few hundredMyr. The luminosity functions (LFs) of main-sequence stars at distances R GC > 21kpc (i.e., >4 disk scale lengths) are matched by models that assume a constant star formation rate (SFR). However, at smaller R GC the LFs suggest that during the past 10Myr the SFR was 2-3 times higher than during the preceding 100Myr. The rings of cool gas that harbor a significant fraction of the current star-forming activity are traced by stars with ages 100Myr, indicating that (1) these structures have ages of at least 100Myr and (2) stars in these structures do not follow the same relation between age and random velocity as their counterparts throughout the disks of other spiral galaxies, probably due to the inherently narrow orbital angular momentum distribution of the giant molecular clouds in these structures. The distribution of evolved red stars is not azimuthally symmetric, in the sense that the projected density along the northeast segment of the major axis is roughly twice that on the opposite side of the galaxy. The northeast arm of the major axis thus appears to be a fossil star-forming area that dates to intermediate epochs. Such a structure may be the consequence of interactions with a companion galaxy. © 2012. The American Astronomical Society. All rights reserved.. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b1138abf-7d18-4772-982a-4d62b2bac8c7 ER - TY - JOUR TI - Characterization of single-domain antibodies with an engineered disulfide bond DO - 10.1007/978-1-61779-968-6-25 AU - Hussack, G. AU - MacKenzie, C.R. AU - Tanha, J. T2 - Methods in Molecular Biology SN - 1064-3745 SN - 9781617799679 VL - 911 SP - 417 EP - 429 KW - Camelidae single domain antibody KW - nanobody KW - unclassified drug KW - bacterial toxin KW - disulfide KW - article KW - circular dichroism KW - disulfide bond KW - gel permeation chromatography KW - mass spectrometry KW - priority journal KW - protein degradation KW - surface plasmon resonance KW - thermostability KW - amino acid sequence KW - animal KW - Artiodactyla KW - chemistry KW - metabolism KW - molecular genetics KW - protein binding KW - protein engineering KW - protein folding KW - protein stability KW - solubility KW - temperature KW - Amino Acid Sequence KW - Animals KW - Bacterial Toxins KW - Camelids, New World KW - Disulfides KW - Molecular Sequence Data KW - Protein Binding KW - Protein Engineering KW - Protein Folding KW - Protein Stability KW - Proteolysis KW - Single-Domain Antibodies KW - Solubility KW - Temperature AB - Camelidae single-domain antibodies (VHHs) represent a unique class of emerging therapeutics. Similar to other recombinant antibody fragments (e.g., Fabs, scFvs), VHHs are amenable to library screening and selection, but benefit from superior intrinsic biophysical properties such as high refolding efficiency, high solubility, no tendency for aggregation, resistance to proteases and chemical denaturants, and high expression, making them ideal agents for antibody-based drug design. Despite these favorable biophysical characteristics, further improvements to VHH stability are desirable when considering applications in adverse environments like high heat, low humidity, pH extremes, and the acidic, protease-rich gastrointestinal tract. Recently, the introduction of a disulfide bond into the hydrophobic core of camelid VHHs increased antibody thermal and conformational stability. Here, we present additional protocols for characterizing the effects of the introduced disulfide bond on a panel of llama VHHs. Specifically, we employ mass spectrometry fingerprinting analysis of VHH peptides to confirm the presence of the introduced disulfide bond, size exclusion chromatography, and surface plasmon resonance to examine the effects on aggregation state and target affinity, and circular dichroism spectroscopy and protease digestion assays to assess the effects on thermal and proteolytic stability. The disulfide bond stabilization strategy can be incorporated into antibody library design and should lead to hyperstabilized single-domain antibodies (VHHs, VHs), and possibly Fabs and scFvs, if selection pressures such as denaturants or proteases are introduced during antibody selection. © 2012 Springer Science+Business Media, LLC. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : baa0bbba-25a0-43c8-a688-0c8db55534d0 ER - TY - JOUR TI - Pulsed laser deposition of pseudocapacitive metal oxide thin films for supercapacitor applications DO - 10.4028/www.scientific.net/MSF.706-709.884 AU - Yang, D. T2 - Materials Science Forum T3 - 7th International Conference on Processing and Manufacturing of Advanced Materials, THERMEC'2011, 1 August 2011 through 5 August 2011, Quebec City, QC SN - 0255-5476 SN - 9783037853030 VL - 706-709 SP - 884 EP - 889 KW - Amorphous phase KW - Aqueous electrolyte KW - Cyclic durability KW - Different substrates KW - Electrochemical capacitor KW - Material research KW - Metal oxide thin films KW - Oxygen gas pressure KW - Oxygen pressure KW - PLD process KW - Polycrystalline KW - Pseudocapacitive KW - Scan rates KW - Specific capacitance KW - Stainless steel substrates KW - Super capacitor KW - Supercapacitor application KW - Ultracapacitors KW - Amorphous films KW - Amorphous materials KW - Capacitance KW - Capacitors KW - Cyclic voltammetry KW - Deposition KW - Manganese KW - Manganese oxide KW - Metallic compounds KW - Oxide films KW - Oxides KW - Oxygen KW - Programmable logic controllers KW - Pulsed laser deposition KW - Sodium KW - Stainless steel KW - Substrates KW - Thin films KW - Vapor deposition KW - X ray diffraction KW - Pulsed lasers KW - Manganese AB - Thin films of manganese oxides have been prepared by pulsed laser deposition (PLD) process on silicon and stainless steel substrates at different substrate temperatures and oxygen gas pressures. By proper selection of temperature and oxygen pressure during the PLD process, pure phases of Mn 2O 3, Mn 3O 4 as well as an amorphous phase of MnO x were successfully fabricated and characterized by X-ray diffraction. The pseudo-capacitance behaviors of those manganese oxides of different phases have also been evaluated by the electrochemical cyclic voltammetry in 0.1 M Na 2SO 4 aqueous electrolyte. Their specific current and capacitance determined at different scan rates were calculated and compared. The results show that polycrystalline Mn 2O 3 phase has the highest specific current and capacitance, while the values for polycrystalline Mn 3O 4 films are the lowest. The amorphous phase MnOx films have the values sitting in between those of Mn 2O 3 and Mn 3O 4. The specific capacitance of Mn 2O 3 films reaches 200 F/g at 1 mV/sec scan with excellent stability and cyclic durability. This work has demonstrated that PLD is a very promising technique for supercapacitor material research due to its excellent flexibility and capability of controlling microstructures and phases of various materials. © 2012 Trans Tech Publications, Switzerland. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e406e215-db66-45d1-ad6c-e4d07ed49b07 ER - TY - JOUR TI - Detailed high-accuracy megavoltage transmission measurements: A sensitive experimental benchmark of EGSnrc DO - 10.1118/1.4745561 AU - Ali, E.S.M. AU - McEwen, M.R. AU - Rogers, D.W.O. T2 - Medical Physics SN - 0094-2405 VL - 39 IS - 10 SP - 5990 EP - 6003 KW - article KW - instrumentation KW - methodology KW - Monte Carlo method KW - photon KW - quality control KW - radiation scattering KW - radiometry KW - Benchmarking KW - Monte Carlo Method KW - Photons KW - Radiometry KW - Scattering, Radiation AB - Purpose: There are three goals for this study: (a) to perform detailed megavoltage transmission measurements in order to identify the factors that affect the measurement accuracy, (b) to use the measured data as a benchmark for the EGSnrc system in order to identify the computational limiting factors, and (c) to provide data for others to benchmark Monte Carlo codes. Methods: Transmission measurements are performed at the National Research Council Canada on a research linac whose incident electron parameters are independently known. Automated transmission measurements are made on-axis, down to a transmission value of ∼1.7, for eight beams between 10 MV (the lowest stable MV beam on the linac) and 30 MV, using fully stopping Be, Al, and Pb bremsstrahlung targets and no fattening filters. To diversify energy differentiation, data are acquired for each beam using low-Z and high-Z attenuators (C and Pb) and Farmer chambers with low-Z and high-Z buildup caps. Experimental corrections are applied for beam drifts (2), polarity (2.5 typical maximum, 6 extreme), ion recombination (0.2), leakage (0.3), and room scatter (0.8)-the values in parentheses are the largest corrections applied. The experimental setup and the detectors are modeled using EGSnrc, with the newly added photonuclear attenuation included (up to a 5.6 effect). A detailed sensitivity analysis is carried out for the measured and calculated transmission data. Results: The developed experimental protocol allows for transmission measurements with 0.4 uncertainty on the smallest signals. Suggestions for accurate transmission measurements are provided. Measurements and EGSnrc calculations agree typically within 0.2 for the sensitivity of the transmission values to the detector details, to the bremsstrahlung target material, and to the incident electron energy. Direct comparison of the measured and calculated transmission data shows agreement better than 2 for C (3.4 for the 10 MV beam) and typically better than 1 for Pb. The differences can be explained by acceptable photon cross section changes of 0.4. Conclusions: Accurate transmission measurements require accounting for a number of influence quantities which, if ignored, can collectively introduce errors larger than 10. Accurate transmission calculations require the use of the most accurate data and physics options available in EGSnrc, particularly the more accurate bremsstrahlung angular sampling option and the newly added modeling of photonuclear attenuation. Comparison between measurements and calculations implies that EGSnrc is accurate within 0.2 for relative ion chamber response calculations. Photon cross section uncertainties are the ultimate limiting factor for the accuracy of the calculated transmission data (Monte Carlo or analytical). © 2012 American Association of Physicists in Medicine. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9a6d8ea1-f068-454c-bd4e-70d483e225a9 ER - TY - JOUR TI - Identification and recombinant expression of anandamide hydrolyzing enzyme from Dictyostelium discoideum DO - 10.1186/1471-2180-12-124 AU - Neelamegan, D. AU - Schoenhofen, I.C. AU - Richards, J.C. AU - Cox, A.D. T2 - BMC Microbiology SN - 1471-2180 VL - 12 SP - 124 KW - anandamide KW - epitope KW - fatty acid amidase KW - hybrid protein KW - article KW - catalysis KW - Dictyostelium discoideum KW - DNA sequence KW - Escherichia coli KW - fruiting body KW - in vivo study KW - life cycle KW - nonhuman KW - nucleotide sequence KW - protein expression KW - protein localization KW - sequence analysis KW - Amidohydrolases KW - Amino Acid Sequence KW - Arachidonic Acids KW - Cloning, Molecular KW - Computational Biology KW - Dictyostelium KW - DNA, Complementary KW - Endocannabinoids KW - Escherichia coli KW - Gene Expression KW - Gene Expression Profiling KW - Membrane Proteins KW - Molecular Sequence Data KW - Polyunsaturated Alkamides KW - Recombinant Proteins KW - Sequence Alignment KW - Sequence Homology, Amino Acid KW - Substrate Specificity KW - Dictyostelium KW - Dictyostelium discoideum KW - Eukaryota AB - Background: Anandamide (Arachidonoyl ethanolamide) is a potent bioactive lipid studied extensively in humans, which regulates several neurobehavioral processes including pain, feeding and memory. Bioactivity is terminated when hydrolyzed into free arachidonic acid and ethanolamine by the enzyme fatty acid amide hydrolase (FAAH). In this study we report the identification of a FAAH homolog from Dictyostelium discoideum and its function to hydrolyze anandamide. Results: A putative FAAH DNA sequence coding for a conserved amidase signature motif was identified in the Dictyostelium genome database and the corresponding cDNA was isolated and expressed as an epitope tagged fusion protein in either E.coli or Dictyostelium. Wild type Dictyostelium cells express FAAH throughout their development life cycle and the protein was found to be predominantly membrane associated. Production of recombinant HIS tagged FAAH protein was not supported in E.coli host, but homologous Dictyostelium host was able to produce the same successfully. Recombinant FAAH protein isolated from Dictyostelium was shown to hydrolyze anandamide and related synthetic fatty acid amide substrates. Conclusions: This study describes the first identification and characterisation of an anandamide hydrolyzing enzyme from Dictyostelium discoideum, suggesting the potential of Dictyostelium as a simple eukaryotic model system for studying mechanisms of action of any FAAH inhibitors as drug targets. © 2012 Monecke et al.; licensee BioMed Central Ltd. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 50e627c0-7c70-478a-9867-25c1676a7c6e ER - TY - JOUR TI - Estimating diets of Atlantic salmon (Salmo salar) using fatty acid signature analyses; validation with controlled feeding studies DO - 10.1139/F2012-039 AU - Budge, S.M. AU - Penney, S.N. AU - Lall, S.P. T2 - Canadian Journal of Fisheries and Aquatic Sciences SN - 0706-652X VL - 69 IS - 6 SP - 1033 EP - 1046 KW - calibration KW - diet KW - fatty acid KW - metabolism KW - muscle KW - quantitative analysis KW - salmonid fishery KW - Clupeidae KW - Euphausiacea KW - Salmo salar KW - Salmonidae AB - Diets incorporating homogeneous binary mixtures of herring or krill oil were fed to Atlantic salmon (Salmo salar) for 22 weeks, and belly flap and muscle tissues were then analyzed for fatty acid (FA) composition. Quantitative fatty acid signature analysis (QFASA) was able to estimate proportions of major dietary components within ~10% of actual values, but the accuracy of the estimates depended on the FA set and calibration coefficients (CC) used in the modelling. FAs present at low levels had little influence on estimates, despite having only dietary sources; the FA set used in the modelling must incorporate the major FAs in tissues to ensure accurate estimates of diet. CC, which reflect modifications that consumers make to dietary FAs, were similar in the two tissues but varied with diet. When CC were applied to correct for fish metabolism, QFASA tended to overestimate the dietary component that had been fed to determine the CC. Diet estimates were most accurate when CC that had been developed from feeding the krill oil-based diet were applied. This first application of QFASA to fish therefore establishes a set of FAs and CC to begin to investigate diets of salmonids. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e096bbed-a502-43bd-9a5c-01a36f2e951e ER - TY - JOUR TI - The human phosphotyrosine signaling network: Evolution and hotspots of hijacking in cancer DO - 10.1101/gr.128819.111 AU - Li, L. AU - Tibiche, C. AU - Fu, C. AU - Kaneko, T. AU - Moran, M.F. AU - Schiller, M.R. AU - Li, S.S.-C. AU - Wang, E. T2 - Genome Research SN - 1088-9051 VL - 22 IS - 7 SP - 1222 EP - 1230 KW - phosphotyrosine KW - protein SH2 KW - protein tyrosine kinase KW - article KW - cell interaction KW - eukaryote KW - human KW - intracellular signaling KW - neoplasm KW - nonhuman KW - priority journal KW - protein binding KW - protein expression KW - Animals KW - Cell Communication KW - Cell Membrane KW - Cytoplasm KW - Evolution, Molecular KW - Humans KW - Models, Genetic KW - Neoplasms KW - Organ Specificity KW - Phosphorylation KW - Phosphotyrosine KW - Phylogeny KW - Protein Binding KW - Protein-Tyrosine Kinases KW - Signal Transduction KW - src Homology Domains KW - Bilateria KW - Eukaryota KW - Metazoa KW - Vertebrata AB - Phosphotyrosine (pTyr) signaling, which plays a central role in cell-cell and cell-environment interactions, has been considered to be an evolutionary innovation in multicellular metazoans. However, neither the emergence nor the evolution of the human pTyr signaling system is currently understood. Tyrosine kinase (TK) circuits, each of which consists of a TK writer, a kinase substrate, and a related reader, such as Src homology (SH) 2 domains and pTyr-binding (PTB) domains, comprise the core machinery of the pTyr signaling network. In this study, we analyzed the evolutionary trajectories of 583 literature-derived and 50,000 computationally predicted human TK circuits in 19 representative eukaryotic species and assigned their evolutionary origins. We found that human TK circuits for intracellular pTyr signaling originated largely from primitive organisms, whereas the inter- or extracellular signaling circuits experienced significant expansion in the bilaterian lineage through the "back- wiring" of newly evolved kinases to primitive substrates and SH2/PTB domains. Conversely, the TK circuits that are involved in tissue-specific signaling evolved mainly in vertebrates by the back-wiring of vertebrate substrates to primitive kinases and SH2/PTB domains. Importantly, we found that cancer signaling preferentially employs the pTyr sites, which are linked to more TK circuits. Our work provides insights into the evolutionary paths of the human pTyr signaling circuits and suggests the use of a network approach for cancer intervention through the targeting of key pTyr sites and their associated signaling hubs in the network. © 2012, Published by Cold Spring Harbor Laboratory Press. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 35702173-68da-496f-b06a-7b4eb6137a17 ER - TY - JOUR TI - Amniotic stem cells: Potential in regenerative medicine DO - 10.1155/2012/530674 AU - Bani-Yaghoub, M. AU - Wilson, P. AU - Hengstschläger, M. AU - Nikaido, T. AU - Pei, D. T2 - Stem Cells International SN - 1687-9678 SP - 530674 KW - bone morphogenetic protein KW - connexin 43 KW - transcription factor KW - acute lung injury KW - adult stem cell KW - amniocentesis KW - amnion KW - amniotic stem cell KW - cell cloning KW - cell communication KW - cell culture KW - cell differentiation KW - cell isolation KW - chronic lung injury KW - connective tissue KW - editorial KW - embryo cell KW - embryonic stem cell KW - flow cytometry KW - gap junction KW - human KW - immunocytochemistry KW - immunomodulation KW - lung injury KW - medical research KW - mesenchymal stem cell KW - paracrine signaling KW - pluripotent stem cell KW - priority journal KW - protein expression KW - regenerative medicine KW - stem cell KW - stem cell transplantation KW - tissue engineering KW - tissue regeneration KW - tissue repair DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f62b687a-c6f1-4389-9b00-285958296d82 ER - TY - JOUR TI - The discovery of an ultra-faint star cluster in the constellation of Ursa Minor DO - 10.1088/2041-8205/753/1/L15 AU - Muñoz, R.R. AU - Geha, M. AU - Côté, P. AU - Vargas, L.C. AU - Santana, F.A. AU - Stetson, P. AU - Simon, J.D. AU - Djorgovski, S.G. T2 - The Astrophysical Journal Letters SN - 2041-8205 VL - 753 IS - 1 SP - L15 AB - We report the discovery of a new ultra-faint globular cluster in the constellation of Ursa Minor, based on stellar photometry from the MegaCam imager at the Canada-France-Hawaii Telescope. We find that this cluster, Muñoz 1, is located at a distance of 45 ± 5kpc and at a projected distance of only 45′ from the center of the Ursa Minor dwarf spheroidal galaxy. Using a maximum-likelihood technique we measure a half-light radius of 05, or equivalently 7pc, and an ellipticity consistent with being zero. We estimate its absolute magnitude to be M V = -0.4 ± 0.9, which corresponds to L V = 120 +160 - 65 L· and we measure a heliocentric radial velocity of -137 ± 4kms -1 based on Keck/DEIMOS spectroscopy. This new satellite is separate from Ursa Minor by 30kpc and 110km s -1 suggesting the cluster is not obviously associated with the dSph, despite the very close angular separation. Based on its photometric properties and structural parameters we conclude that Muñoz 1 is a new ultra-faint stellar cluster. Along with Segue 3 this is one of the faintest stellar clusters known to date. © 2012. The American Astronomical Society. All rights reserved.. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9663ca44-756f-4627-9079-c4e64ef062e4 ER - TY - JOUR TI - 199.5 K operation of THz quantum cascade lasers AU - Fathololoumi, S. AU - Dupont, E. AU - Chan, C.W.I. AU - Wasilewski, Z.R. AU - Laframboise, S.R. AU - Ban, D. AU - Matyas, A. AU - Jirauschek, C. AU - Hu, Q. AU - Liu, H.C. T2 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012 T3 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012, 6 May 2012 through 11 May 2012, San Jose, CA SN - 9781467318396 SP - 6326043 KW - Density matrix KW - Operating temperature KW - Oscillator strengths KW - THz quantum cascade lasers KW - Quantum cascade lasers KW - Lasers AB - The density matrix based model is employed to design a THz quantum cascade laser with optimized oscillator strength and improved injection tunneling. A maximum operating temperature of 199.5 K has been recorded at 3.22 THz (1.28hω/kκB). © 2012 OSA. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 923017e8-a4bd-46dd-823b-d5573b35d12e ER - TY - JOUR TI - Cj1136 is required for lipooligosaccharide biosynthesis, hyperinvasion, and chick colonization by Campylobacter jejuni DO - 10.1128/IAI.00151-12 AU - Javed, M.A. AU - Cawthraw, S.A. AU - Baig, A. AU - Li, J. AU - McNally, A. AU - Oldfield, N.J. AU - Newell, D.G. AU - Manning, G. T2 - Infection and Immunity SN - 0019-9567 VL - 80 IS - 7 SP - 2361 EP - 2370 KW - bile salt KW - deoxycholate sodium KW - lipooligosaccharide KW - polymyxin B KW - taurocholic acid KW - animal experiment KW - animal model KW - antibiotic resistance KW - antibiotic sensitivity KW - article KW - bacterial colonization KW - bacterial gene KW - bacterial mutation KW - bacterial virulence KW - bacterium adherence KW - Campylobacter jejuni KW - carbohydrate synthesis KW - cell invasion KW - chick KW - controlled study KW - enteritis KW - environmental stress KW - food poisoning KW - gene disruption KW - gene inactivation KW - host pathogen interaction KW - in vitro study KW - in vivo study KW - intestine epithelium cell KW - mutagenesis KW - nonhuman KW - priority journal KW - Animals KW - Campylobacter jejuni KW - Cell Line KW - Chickens KW - Disease Models, Animal KW - DNA Transposable Elements KW - Epithelial Cells KW - Galactosyltransferases KW - Gene Deletion KW - Genetic Complementation Test KW - Humans KW - Lipopolysaccharides KW - Mutagenesis, Insertional KW - Virulence Factors AB - Campylobacter jejuni is a major cause of bacterial food-borne enteritis worldwide, and invasion into intestinal epithelial cells is an important virulence mechanism. Recently we reported the identification of hyperinvasive C. jejuni strains and created a number of transposon mutants of one of these strains, some of which exhibited reduced invasion into INT-407 and Caco-2 cells. In one such mutant the transposon had inserted into a homologue of cj1136, which encodes a putative galactosyltransferase according to the annotation of the C. jejuni NCTC11168 genome. In the current study, we investigated the role of cj1136 in C. jejuni virulence, lipooligosaccharide (LOS) biosynthesis, and host colonization by targeted mutagenesis and complementation of the mutation. The cj1136 mutant showed a significant reduction in invasion into human intestinal epithelial cells compared to the wild-type strain 01/51. Invasion levels were partially restored on complementing the mutation. The inactivation of cj1136 resulted in the production of truncated LOS, while biosynthesis of a full-length LOS molecule was restored in the complemented strain. The cj1136 mutant showed an increase in sensitivity to the bile salts sodium taurocholate and sodium deoxycholate and significantly increased sensitivity to polymyxin B compared to the parental strain. Importantly, the ability of the mutant to colonize 1-day-old chicks was also significantly impaired. This study confirms that a putative galactosyltransferase encoded by cj1136 is involved in LOS biosynthesis and is important for C. jejuni virulence, as disruption of this gene and the resultant truncation of LOS affect both colonization in vivo and invasiveness in vitro. © 2012, American Society for Microbiology. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c16fe2a0-2c97-4571-89f5-474224ae1f91 ER - TY - JOUR TI - Combining structural brain changes improves the prediction of Alzheimer's disease and mild cognitive impairment DO - 10.1159/000339364 AU - Zhang, N. AU - Song, X. AU - Zhang, Y. T2 - Dementia and Geriatric Cognitive Disorders SN - 1420-8008 VL - 33 IS - 5 SP - 318 EP - 326 KW - accuracy KW - aged KW - aging KW - Alzheimer disease KW - article KW - brain atrophy KW - controlled study KW - correlation analysis KW - disease predisposition KW - female KW - follow up KW - human KW - major clinical study KW - male KW - medial temporal lobe atrophy KW - mild cognitive impairment KW - nuclear magnetic resonance imaging KW - predictive value KW - priority journal KW - prognosis KW - Aged KW - Aged, 80 and over KW - Aging KW - Alzheimer Disease KW - Atrophy KW - Brain KW - Case-Control Studies KW - Disease Progression KW - Female KW - Humans KW - Magnetic Resonance Imaging KW - Male KW - Middle Aged KW - Mild Cognitive Impairment KW - Organ Size KW - Predictive Value of Tests KW - Prognosis KW - Sensitivity and Specificity KW - Temporal Lobe AB - Background: Several structural brain changes have been associated with Alzheimer's disease (AD). This study investigated the prediction of AD by combining multiple brain changes with the hallmark medial temporal lobe atrophy (MTA). Methods: High-resolution magnetic resonance imaging (MRI) data of people with mild AD (n = 39), mild cognitive impairment (MCI; n = 82), and of healthy controls (HC; n = 58) were obtained at baseline. Among these people, 26 AD, 53 MCI, and 46 HC subjects had 24-month follow-up MRI scans. Bilateral MTA was evaluated using a medial temporal lobe atrophy scale (MTAS). Common changes in the aging brain were summarized using a brain atrophy and lesion index (BALI). The performance of the MTAS, BALI, and a score combining both, using a logistic regression model, were assessed. Results: The MTAS and BALI scores were closely correlated (r2 > 0.56); each differed between the diagnostic groups. Having an unfavorable MTAS score was associated with an increased risk of MCI-AD conversion (OR = 3.71, p = 0.039), adjusted for age, sex, and education; having an unfavorable BALI score marginally contributed to such risks (OR = 4.08, p = 0.080). Combining MTAS and BALI components resulted in a greater OR (8.99, p = 0.007) and an improved predictive accuracy (75.9%, p = 0.002). Conclusion: Multiple structural changes have an additive effect on AD. The data support potential future roles of combining multiple coexisting structural changes to benefit AD diagnosis, progression monitoring, and/or treatment effect evaluation. Copyright © 2012 S. Karger AG, Basel. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8830aaa1-6987-4d05-aba0-3a285fdb45a0 ER - TY - JOUR TI - Phosphorylcholine allows for evasion of bactericidal antibody by haemophilus influenzae DO - 10.1371/journal.ppat.1002521 AU - Clark, S.E. AU - Snow, J. AU - Li, J. AU - Zola, T.A. AU - Weiser, J.N. T2 - PLoS Pathogens SN - 1553-7366 VL - 8 IS - 3 SP - e1002521 KW - bacterium antibody KW - lipopolysaccharide KW - phosphorylcholine KW - trypsin KW - lipopolysaccharide KW - adaptive immunity KW - animal experiment KW - antigen binding KW - article KW - bacterial colonization KW - bactericidal activity KW - cell surface KW - controlled study KW - flow cytometry KW - Haemophilus influenzae KW - mouse KW - nasopharynx KW - nonhuman KW - outer membrane KW - protein expression KW - survival KW - adaptive immunity KW - animal KW - antibody combining site KW - Bagg albino mouse KW - cell membrane KW - host pathogen interaction KW - human KW - immune evasion KW - immunology KW - mouse mutant KW - pathogenicity KW - Haemophilus influenzae KW - Murinae KW - Adaptive Immunity KW - Animals KW - Binding Sites, Antibody KW - Cell Membrane KW - Haemophilus influenzae KW - Host-Pathogen Interactions KW - Humans KW - Immune Evasion KW - Lipopolysaccharides KW - Mice KW - Mice, Inbred BALB C KW - Mice, SCID KW - Phosphorylcholine AB - The human pathogen Haemophilus influenzae has the ability to quickly adapt to different host environments through phase variation of multiple structures on its lipooligosaccharide (LPS), including phosphorylcholine (ChoP). During colonization with H. influenzae, there is a selection for ChoP+ phase variants. In a murine model of nasopharyngeal colonization, this selection is lost in the absence of adaptive immunity. Based on previous data highlighting the importance of natural antibody in limiting H. influenzae colonization, the effect of ChoP expression on antibody binding and its bactericidal activity was investigated. Flow cytometric analysis revealed that ChoP+ phase variants had decreased binding of antibody to LPS epitopes compared to ChoP- phase variants. This difference in antibody binding correlated with increased survival of ChoP+ phase variants in the presence of antibody-dependent, complement-mediated killing. ChoP+ phase variants were also more resistant to trypsin digestion, suggesting a general effect on the physical properties of the outer membrane. Moreover, ChoP-mediated protection against antibody binding correlated with increased resilience of outer membrane integrity. Collectively, these data suggest that ChoP expression provides a selective advantage during colonization through ChoP-mediated effects on the accessibility of bactericidal antibody to the cell surface. © 2012 Clark et al. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b548c2de-8239-4c2d-a9f9-bca2b35eb461 ER - TY - JOUR TI - Detailed numerical simulation of single-walled carbon nanotube synthesis in a radio-frequency induction thermal plasma system DO - 10.1088/1742-6596/406/1/012011 AU - Esfarjani, S.A. AU - Dworkin, S.B. AU - Mostaghimi, J. AU - Kim, K.S. AU - Kingston, C.T. AU - Simard, B. AU - Soucy, G. T2 - Journal of Physics: Conference Series T3 - 12th High-Tech Plasma Processes Conference, HTPP 2012, 24 June 2012 through 29 June 2012, Bologna SN - 1742-6588 VL - 406 IS - 1 SP - 12011 KW - Axisymmetric KW - CFD codes KW - Chemical model KW - Chemistry models KW - Different operating conditions KW - Induction thermal plasma KW - Metal catalyst KW - Modified model KW - Numerical calculation KW - Radio frequencies KW - RF plasma KW - RF plasma systems KW - Single-walled carbon KW - Thermofluid fields KW - Yield rates KW - Carbon clusters KW - Chemical reactions KW - Computational fluid dynamics KW - Computer simulation KW - Forecasting KW - Plasma devices KW - Reaction rates KW - Single-walled carbon nanotubes (SWCN) KW - Wave plasma interactions KW - Plasma theory AB - 2D axisymmetric numerical calculations are conducted to model the thermo-fluid fields and chemical reactions leading to the formation of SWCNTs in an RF plasma system. A modified version of the SWCNT "reduced" chemical model is used to estimate the formation of SWCNT in an RF plasma system for the first time. The "reduced" model incorporates 14 species and 36 chemical reactions to predict the formation of metal and carbon clusters and SWCNTs. By combing the chemistry model into the RF plasma CFD code, the formation and development of carbon and metal catalyst clusters and their reactions which produce SWCNTs are shown. The chemistry model is shown to under-predict the yield rate of SWCNT. In order to better predict the yield rate, a sensitivity analysis is performed to modify the dominant reaction rates. The modified model predicts the yield of SWCNTs correctly within the range reported experimentally. However, more studies should be conducted to validate the accuracy of the model for different operating conditions. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fdabf989-abbc-4c0d-b38a-5219ac59fa98 ER - TY - JOUR TI - Performance modeling for the RAVEN Multi-Object Adaptive Optics demonstrator DO - 10.1086/665924 AU - Andersen, D.R. AU - Jackson, K.J. AU - Blain, C. AU - Bradley, C. AU - Correia, C. AU - Ito, M. AU - Lardière, O. AU - Véran, J.-P. T2 - Publications of the Astronomical Society of the Pacific SN - 0004-6280 VL - 124 IS - 915 SP - 469 EP - 484 AB - RAVEN will be a Multi-Object Adaptive Optics (MOAO) technology and science demonstrator on the Subaru telescope. The baseline design calls for three natural guide star (NGS) wavefront sensors (WFS) and two science pickoff arms that will patrol a ~2′ diameter field of regard (FOR). Sky coverage is an important consideration, because RAVEN is both a technical and science demonstrator. Early-stage simulation of RAVEN's performance is critical in establishing that the key science requirement can be met. That is, 30% of the energy of an unresolved pointspread function (PSF) be ensquared within a 140 mas slit using existing WFS camera and deformable mirror (DM) technology. The system was simulated with two independent modeling tools, MAOS and OOMAO, which were in excellent agreement. It was established that RAVEN will be an order 10 × 10 adaptive optics (AO) system by examining the tradeoffs between performance, sky coverage, and WFS field of view. The 30% ensquared-energy (EE) requirement will be met with three NGSs and will exceed 40% if the Subaru Laser Guide Star (LGS) is used onaxis (assuming median image quality). This is also true for NGSs as faint as m R = 14:5. © 2012. The Astronomical Society of the Pacific. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b4a77a6b-b115-429f-8f6e-ee45f267ec03 ER - TY - JOUR TI - The Carina project. V. The impact of NLTE effects on the iron content DO - 10.1086/666480 AU - Fabrizio, M. AU - Merle, T. AU - Thévenin, F. AU - Nonino, M. AU - Bono, G. AU - Stetson, P.B. AU - Ferraro, I. AU - Iannicola, G. AU - Monelli, M. AU - Walker, A.R. AU - Buonanno, R. AU - Caputo, F. AU - Corsi, C.E. AU - Dall'Ora, M. AU - Degl'Innocenti, S. AU - François, P. AU - Gilmozzi, R. AU - Marconi, M. AU - Pietrinferni, A. AU - Prada Moroni, P.G. AU - Primas, F. AU - Pulone, L. AU - Ripepi, V. AU - Romaniello, M. T2 - Publications of the Astronomical Society of the Pacific SN - 0004-6280 VL - 124 IS - 916 SP - 519 EP - 534 AB - We have performed accurate iron abundance measurements for 44 red giants (RGs) in the Carina dwarf spheroidal (dSph) galaxy. We used archival, high-resolution spectra (R ~ 38, 000) collected with UVES at ESO/VLT either in slit mode (five RGs) or in fiber mode (39 RGs, FLAMES/GIRAFFE-UVES). The sample is more than a factor of 4 larger than any previous spectroscopic investigation of stars in dSphs based on high-resolution (R ≥ 38000) spectra. We did not impose the ionization equilibrium between neutral and singly ionized iron lines. The effective temperatures and the surface gravities were estimated by fitting stellar isochrones in the V, B - V color-magnitude diagram. To measure the iron abundance of individual lines we applied the LTE spectrum-synthesis fitting method using MARCS model atmospheres of appropriate metallicity. For the 27 stars for which we measured both Fe I and Fe II abundances, we found evidence of NLTE effects between neutral and singly ionized iron abundances. The difference is ~0.1 dex, on average, but steadily increases when moving from the metal-rich to the metal-poor regime. Moreover, the two metallicity distributions differ at the 97% confidence level. Assuming that the Fe II abundances are minimally affected by NLTE effects, we corrected the Fe I stellar abundances using a linear fit between Fe I and Fe II stellar abundance determinations. We found that the Carina metallicity distribution based on the corrected Fe I abundances (44 RGs) has a weighted mean metallicity of [Fe/H] = -1.80 and a weighted standard deviation of σ = 0.24 dex. The Carina metallicity distribution based on the Fe II abundances (27 RGs) gives similar estimates ([Fe/H] = -1.72, σ = 0.24 dex). The current weighted mean metallicities are slightly more metal-poor when compared with similar estimates available in the literature. Furthermore, when we restricted our analysis to stars with the most accurate iron abundances, ~20 Fe I and at least three Fe II measurements (15 stars), we found that the range in iron abundances covered by Carina RGs (~1 dex) agreed quite well with similar estimates based on high-resolution spectra; however, it is a factor of 2-3 smaller than abundance estimates based on the near-infrared calcium triplet. This finding supports previous estimates based on photometric metallicity indicators. © 2012. The Astronomical Society of the Pacific. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 65bfda45-0fab-4fa6-b5c6-7dcf820cb192 ER - TY - JOUR TI - InGaN laser diodes operating at 450-460 nm grown by rf-plasma MBE DO - 10.1116/1.3665223 AU - Skierbiszewski, C. AU - Siekacz, M. AU - Turski, H. AU - Muzioł, G. AU - Sawicka, M. AU - Feduniewicz-Zmuda, A. AU - Smalc-Koziorowska, J. AU - Perlin, P. AU - Grzanka, S. AU - Wasilewski, Z.R. AU - Kucharski, R. AU - Porowski, S. T2 - Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures SN - 1071-1023 VL - 30 IS - 2 SP - 02B102 KW - Blue laser diodes KW - GaN substrate KW - Growth technologies KW - High-nitrogen KW - InGaN laser diodes KW - InGaN quantum wells KW - Light loss KW - Plasma assisted molecular beam epitaxy KW - RF plasma KW - Single quantum well KW - Threading dislocation densities KW - Vacuum applications KW - Gallium nitride AB - This work demonstrates the first true blue laser diodes (LDs) grown by plasma assisted molecular beam epitaxy that operate at the region of 450-460 nm. The single quantum well LDs were grown on several types of c-plane bulk GaN substrates, with threading dislocation densities varying from 10 4 to 10 8cm -2. The key factors that allowed the authors to achieve lasing in true-blue wavelengths are improvements in the growth technology of the InGaN quantum wells attributed to the high nitrogen flux used and the design of the LD structure, which reduced the light losses in the cavity. The authors discuss the influence of the diodes' design on the parameters of LDs. © 2012 American Vacuum Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b7cbc727-caae-4321-ad01-288b02cccbdc ER - TY - JOUR TI - Search for z ∼ 7 Lyα emitters with the Suprime-Cam at the Subaru telescope DO - 10.1088/0004-637X/744/2/89 AU - Hibon, P. AU - Kashikawa, N. AU - Willott, C. AU - Iye, M. AU - Shibuya, T. T2 - The Astrophysical Journal SN - 0004-637X VL - 744 IS - 2 SP - 89 AB - We report a search for z = 7 Lyα emitters (LAEs) using a custom-made narrowband filter centered at 9755 Å with the Suprime-Cam instrument installed at the Subaru telescope. We observed two different fields and obtained two samples of seven LAEs, of which four are robust in each field. We cover the luminosity range of 9.1042-2.1043 erg s-1 in comoving volumes of ∼4 × 105 and 4.3 × 105 Mpc3. From this result, we derived possible z ∼ 7 Lyα luminosity functions for the full samples and for a subsample of four objects in each field. We do not observe, in each case, any strong evolution between the z = 6.5 and z ∼ 7 Lyα luminosity functions. Spectroscopic confirmation for these candidate samples is required to establish a definitive measure of the luminosity function at z ∼ 7. © 2012. The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 16ae6428-e007-485b-9b1b-7f9260002a0e ER - TY - JOUR TI - Identification and characterization of a lipopolysaccharide α,2,3-sialyltransferase from the human pathogen Helicobacter bizzozeronii DO - 10.1128/JB.00126-12 AU - Kondadi, P.K. AU - Rossi, M. AU - Twelkmeyer, B. AU - Schur, M.J. AU - Li, J. AU - Schott, T. AU - Paulin, L. AU - Auvinen, P. AU - Hänninen, M.-L. AU - Schweda, E.K.H. AU - Wakarchuk, W. T2 - Journal of Bacteriology SN - 0021-9193 VL - 194 IS - 10 SP - 2540 EP - 2550 KW - alpha, 2,3 sialyltransferase KW - bacterial enzyme KW - bacterium lipopolysaccharide KW - n acetylneuraminic acid KW - sialic acid KW - sialidase KW - sialyl Lewis x antigen KW - sialyltransferase KW - unclassified drug KW - anion exchange chromatography KW - article KW - bacterial genome KW - bacterial strain KW - bacterium isolate KW - carbohydrate synthesis KW - gene sequence KW - Helicobacter KW - Helicobacter bizzozeronii KW - human KW - nonhuman KW - nucleotide sequence KW - polyacrylamide gel electrophoresis KW - priority journal KW - protein expression KW - sialylation KW - Animals KW - Antibodies, Bacterial KW - Cholera Toxin KW - Dogs KW - Gene Expression Regulation, Bacterial KW - Genome, Bacterial KW - Helicobacter KW - Humans KW - Lipopolysaccharides KW - Molecular Sequence Data KW - Multigene Family KW - Phylogeny KW - Recombinant Proteins KW - Sialyltransferases KW - Canis familiaris KW - Helicobacter KW - Helicobacter bizzozeronii KW - Mammalia AB - Terminal sialic acid in the lipopolysaccharides (LPSs) of mucosal pathogens is an important virulence factor. Here we report the characterization of a Helicobacter sialyltransferase involved in the biosynthesis of sialylated LPS in Helicobacter bizzozeronii, the only non-pylori gastric Helicobacter species isolated from humans thus far. Starting from the genome sequences of canine and human strains, we identified potential sialyltransferases downstream of three genes involved in the biosynthesis of N-acetylneuraminic acid. One of these candidates showed monofunctional α,2,3-sialyltransferase activity with a preference for N-acetyllactosamine as a substrate. The LPSs from different strains were shown by SDS-PAGE and high-performance anionexchange chromatography with pulsed amperometric detection (HPAEC-PAD) to contain sialic acid after neuraminidase treatment. The expression of this sialyltransferase and sialyl-LPS appeared to be a phase-variable characteristic common to both human and canine H. bizzozeronii strains. The sialylation site of the LPSs of two H. bizzozeronii strains was determined to be NeuAc-Hex-HexNAc, suggesting terminal 3'-sialyl-LacNAc. Moreover, serological typing revealed the possible presence of sialyl-Lewis X in two additional strains, indicating that H. bizzozeronii could also mimic the surface glycans of mammalian cells. The expression of sialyl-glycans may influence the adaptation process of H. bizzozeronii during the host jump from dogs to humans. © 2012, American Society for Microbiology. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 94cbe54f-c12d-4664-8f68-dab3dd12bf51 ER - TY - JOUR TI - Effect of surface modification by ammonia plasma on vascular graft: PET film and PET scaffold AU - Öteyaka, M.Ö. AU - Chevallier, P. AU - Robitaille, L. AU - Laroche, G. T2 - Acta Physica Polonica A SN - 0587-4246 VL - 121 IS - 1 SP - 125 EP - 127 KW - Amino group KW - Ammonia plasma KW - Aromatic rings KW - Bulk properties KW - Flat surfaces KW - High-resolution spectra KW - Low pressure ammonia KW - PET films KW - Plasma treatment KW - Polymer surfaces KW - Porous surface KW - Size and shape KW - Thrombogenicity KW - Treatment time KW - Vascular grafts KW - Ammonia KW - Atomic force microscopy KW - Ethylene KW - Grafting (chemical) KW - Grafts KW - Materials properties KW - Plasma applications KW - Polyethylene terephthalates KW - Scaffolds (biology) KW - Surface treatment KW - Weaving KW - Nitrogen plasma AB - Nowadays, poly (ethylene terephthalate) (PET) textiles, either knitted or woven, are largely used as substitutes for replacement of medium and large calibre (10-40 mm) arteries. Unfortunately, these substitutes do not perform well when they are used to replace small diameter arteries due to thrombogenicity and compliance mismatch issues. Surface treatments were often used as the first step to solve thrombogenicity issues. For example, low pressure ammonia plasma processes can provide modification of the top ≈ 10-50 Å of polymer surface without affecting bulk properties of materials. This work compared ammonia plasma surface modifications of PET film (flat surface) and PET scaffolds (porous surface). Plasma treatments lead to a higher amount of nitrogen as well as amino groups on scaffolds compared to films. N/C maximum was reached for PET film and scaffold after plasma treatments of 5 s and 100 s, respectively. Highest amine concentration on films and scaffolds were obtained at short treatment time, specifically 1 s. In addition, high resolution spectra of C 1s confirmed that amino groups were mainly grafted on aromatic rings. Nodule formation was observed after plasma treatment with atomic force microscopy. Their size and shape increased with longer treatment time. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4e054681-ecba-45cb-8d5b-89eef7d2abf8 ER - TY - JOUR TI - Flexure mount for a MEMS deformable mirror for the GPI Planet Imager DO - 10.1117/12.926842 AU - Hill, A. AU - Cornelissen, S. AU - Dillon, D. AU - Lam, C. AU - Palmer, D. AU - Saddlemeyer, L. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Modern Technologies in Space- and Ground-Based Telescopes and Instrumentation II, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491510 VL - 8450 SP - 84500H KW - Adaptive optics systems KW - Deformable mirrors KW - Field application KW - Flexure mounts KW - Flexures KW - Gravity vectors KW - Laboratory environment KW - Laboratory set-up KW - Mechanical design KW - MEMS deformable mirror KW - MEMS DM KW - Micromachines KW - Mirror surfaces KW - Optical mountings KW - Optical surfaces KW - Opto-mechanical mount KW - Opto-mechanical mounting KW - Preliminary design KW - Thermal condition KW - Thermal fluctuations KW - Thermally stable KW - Adaptive optics KW - Electromechanical devices KW - Finite element method KW - Laser pulses KW - MEMS KW - Optical telescopes KW - Telescopes KW - Mountings AB - Small deformable mirrors (DMs) produced using microelectromechanical systems (MEMS) techniques have been used in thermally stable, bench-top laboratory environments. With advances in MEMS DM technology, a variety of field applications are becoming more common, such as the Gemini Planet Imager's (GPI) adaptive optics system. Instruments at the Gemini Observatory operate in conditions where fluctuating ambient temperature, varying gravity orientations and humidity and dust can have a significant effect on DM performance. As such, it is crucial that the mechanical design of the MEMS DM mount be tailored to the environment. GPI's approach has been to mount a 4096 actuator MEMS DM, developed by Boston Micromachines Corporation, using high performance optical mounting techniques rather than a typical laboratory set-up. Flexures are incorporated into the DM mount to reduce deformations on the optical surface due to thermal fluctuations. These flexures have also been sized to maintain alignment under varying gravity vector orientations. This paper is a follow-up to a previous paper which presented the preliminary design. The completed design of the opto-mechanical mounting scheme is discussed and results from finite element analysis are presented, including predicting the stability of the mirror surface in varying gravity vectors and thermal conditions. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 043e643d-0826-4634-acbf-40ece425fd7a ER - TY - CHAP TI - Editorial message: Special track on bioinformatics AU - Tulpan, D. AU - Lecca, P. AU - Jordan, F. T2 - Proceedings of the ACM Symposium on Applied Computing T3 - 27th Annual ACM Symposium on Applied Computing, SAC 2012, 26 March 2012 through 30 March 2012, Trento SN - 9781450308571 SP - 1347 EP - 1348 DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e71c09d9-7521-464a-8a06-1a3bd220a798 ER - TY - JOUR TI - The utility of near infrared imaging in intra-operative prediction of flap outcome: A reverse McFarlane skin flap model study DO - 10.1255/1007 AU - Sowa, M.G. AU - Friesen, J.R. AU - Levasseur, M. AU - Schattk, B. AU - Sigurdson, L. AU - Hayakawa, T. T2 - Journal of Near Infrared Spectroscopy SN - 0967-0335 VL - 20 IS - 5 SP - 601 EP - 615 AB - Skin flaps are complex procedures used extensively in reconstructive surgery that require post-operative monitoring to ensure that they do not fail. Near infrared (NIR) spectroscopic imaging is a convenient, non-invasive method for surgeons to examine flaps during surgery and in the early post-operative period. Using a reverse McFarlane skin flap model, we show that model-free chemometric methods as well as simple modified Beer-Lambert analysis of the NIR images provide insights into the blood supply to flaps and demonstrate that the technique can detect and localise perfusion-related complications as well as give real-time feedback to the surgeon as they try to resolve the complication. We also show that using estimates of tissue haemoglobin oxygen saturation, imaging measurements made during surgery and in the early post-operative period are highly predictive of the outcome of the flap tissue with specificities and sensitivities exceeding 85%. © IM Publications LLP 2012. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0b14fc78-a1d7-456b-8232-4f30c9eaac63 ER - TY - JOUR TI - Simulation model based approach for long exposure atmospheric point spread function reconstruction for laser guide star multiconjugate adaptive optics DO - 10.1364/AO.51.007443 AU - Gilles, L. AU - Correia, C. AU - Véran, J.-P. AU - Wang, L. AU - Ellerbroek, B. T2 - Applied Optics SN - 0003-6935 VL - 51 IS - 31 SP - 7443 EP - 7458 KW - Classical schemes KW - Differential photometry KW - Field of views KW - Fourier KW - Laser guide star KW - Multiconjugate adaptive optics KW - Point spread function reconstruction KW - Post-processing system KW - Real systems KW - Reconstruction accuracy KW - Simulation model KW - Telemetry data KW - Thirty Meter Telescope KW - Adaptive optics KW - Astrophysics KW - Lasers KW - Optical transfer function KW - Stars KW - Computer simulation AB - This paper discusses an innovative simulation model based approach for long exposure atmospheric point spread function (PSF) reconstruction in the context of laser guide star (LGS) multiconjugate adaptive optics (MCAO). The approach is inspired from the classical scheme developed by Véran et al. [J. Opt. Soc. Am. A 14, 3057 (1997)] and Flicker et al. [Astron. Astrophys. 400, 1199 (2003)] and reconstructs the long exposure optical transfer function (OTF), i.e., the Fourier transformed PSF, as a product of separate long-exposure tip/tilt removed and tip/tilt OTFs, each estimated by postprocessing system and simulation telemetry data. Sample enclosed energy results assessing reconstruction accuracy are presented for the Thirty Meter Telescope LGS MCAO system currently under design and show that percent level absolute and differential photometry over a 30 arcsec diameter field of view are achievable provided the simulation model faithfully represents the real system. © 2012 Optical Society of America. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ed41cea3-db35-4d53-baa2-4c8f26f746b7 ER - TY - JOUR TI - Structure of the O-antigen polysaccharide present in the lipopolysaccharide of Cronobacter dublinensis (subspecies lactaridi or lausannensis) HPB 3169 DO - 10.1139/W2012-022 AU - MacLean, L.L. AU - Vinogradov, E. AU - Pagotto, F. AU - Perry, M.B. T2 - Canadian Journal of Microbiology SN - 0008-4166 VL - 58 IS - 4 SP - 540 EP - 546 KW - 3 deoxy manno octulosonic acid KW - 3 hydroxybutyric acid KW - 3,6 dideoxy 3 3 hydroxybutyramido dextro glucose KW - bacterium lipopolysaccharide KW - glucose derivative KW - n acetylglucosamine KW - O antigen KW - pentasaccharide KW - polymer KW - rhamnose KW - unclassified drug KW - antigen KW - bacterium KW - nuclear magnetic resonance KW - pathogen KW - polymer KW - polysaccharide KW - antigen structure KW - article KW - bacterial growth KW - bacterium isolation KW - carbohydrate analysis KW - Cronobacter dublinensis KW - hydrolysis KW - molecular weight KW - nonhuman KW - nuclear magnetic resonance KW - peroxidation KW - priority journal KW - Acetylglucosamine KW - Amino Acid Sequence KW - Carbohydrate Sequence KW - Cronobacter KW - Glucose KW - Hydrolysis KW - Lipopolysaccharides KW - Magnetic Resonance Spectroscopy KW - O Antigens KW - Oligosaccharides KW - Bacteria (microorganisms) KW - Enterobacter sakazakii KW - Negibacteria AB - Cronobacter dublinensis (formerly Enterobacter sakazakii) HPB 3169 is a pathogenic Gram-negative bacterium that produces a smooth-type lipopolysaccharide in which the antigenic O-polysaccharide component was determined to be a repeating pentasaccharide unit composed of L-rhamnose; 2-acetamido-2-deoxy-D-glucose; 3,6-dideoxy-3-(R)-3-hydroxybutyramido-Dglucose; and 3-deoxy-manno-oct-2-ulosonic acid in the respective molar ratio 2:1:1:1. Chemical and 2D NMR analyses of the O-polysaccharide and a pentasaccharide derived by the mild acid hydrolysis of the ketosyl linkage of the Kdo (3-deoxy-D-manno-2-octulosonic acid) residue in the O-polysaccharide established that the O-antigen is a high molecular mass unbranched polymer of a repeating pentasaccharide unit and has the structure where Bu is a (R)-3-hydroxybutanoyl substituent. The O-antigen is structurally similar to that of the recently reported Cronobacter sakazakii strain G706 (designated as serotype O5), except that in strain G706 the D-Qui3N is in its N-acetyl form, in contrast to its presence as a 3-deoxy-3-(R)-3-hydroxybutyramido derivative in the C. sakazakii HPB 3169 strain O-antigen. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 592b7849-d4ca-444b-a261-f0b199aefac1 ER - TY - JOUR TI - Effects of core flow swirl on the flow characteristics of a scalloped forced mixer DO - 10.1115/1.4005968 AU - Lei, Z. AU - Mahallati, A. AU - Cunningham, M. AU - Germain, P. T2 - Journal of Engineering for Gas Turbines and Power SN - 0742-4795 VL - 134 IS - 11 SP - 111201 KW - Core flow KW - Equivalent diameter KW - Experimental investigations KW - Flow characteristic KW - Inlet swirls KW - Low swirl KW - Normal vortices KW - Pressure ratio KW - Radial velocity KW - Reversed flow KW - Streamwise vortices KW - Swirl angles KW - Temperature ratio KW - Thrust loss KW - Turbulence intensity KW - Vane geometry KW - Velocity ratio KW - Acoustic streaming KW - Deformation KW - Mixers (machinery) KW - Mixing KW - Reynolds number KW - Vortex flow KW - Bypass ratio AB - This paper presents a detailed experimental investigation of the influence of core flow swirl on the mixing and performance of a scaled turbofan mixer with 12 scalloped lobes. Measurements were made downstream of the mixer in a coaxial wind tunnel. The core-to-bypass velocity ratio was set to 2:1, temperature ratio to 1.0, and pressure ratio to 1.03, giving a Reynolds number of 5.2×10 5, based on the core flow velocity and equivalent diameter. In the core flow, the background turbulence intensity was raised to 5 and the swirl angle was varied from 0 deg to 30 deg with five vane geometries. At low swirl angles, additional streamwise vortices were generated by the deformation of normal vortices due to the scalloped lobes. With increased core swirl, greater than 10 deg, the additional streamwise vortices were generated mainly due to radial velocity deflection, rather than stretching and deformation of normal vortices. At high swirl angles, stronger streamwise vortices and rapid interaction between various vortices promoted downstream mixing. Mixing was enhanced with minimal pressure and thrust losses for the inlet swirl angles less than 10 deg. However, the reversed flow downstream of the center body was a dominant contributor to the loss of thrust at the maximum core flow swirl angle of 30 deg. © 2012 American Society of Mechanical Engineers. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 064be747-e0cc-4a0f-afdd-64af83ddb768 ER - TY - JOUR TI - Physics of lateral triple quantum-dot molecules with controlled electron numbers DO - 10.1088/0034-4885/75/11/114501 AU - Hsieh, C.-Y. AU - Shim, Y.-P. AU - Korkusinski, M. AU - Hawrylak, P. T2 - Reports on Progress in Physics SN - 0034-4885 VL - 75 IS - 11 SP - 114501 AB - We review the recent progress in theory and experiments with lateral triple quantum dots with controlled electron numbers down to one electron in each dot. The theory covers electronic and spin properties as a function of topology, number of electrons, gate voltage and external magnetic field. The orbital Hund's rules and Nagaoka ferromagnetism, magnetic frustration and chirality, interplay of quantum interference and electron-electron interactions and geometrical phases are described and related to charging and transport spectroscopy. Fabrication techniques and recent experiments are covered, as well as potential applications of triple quantum-dot molecule in coherent control, spin manipulation and quantum computation. © 2012 IOP Publishing Ltd. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d13cad1f-e9cf-4dd4-b234-711062069085 ER - TY - JOUR TI - An inexpensive liquid crystal spectropolarimeter for the dominion astrophysical observatory plaskett telescope DO - 10.1086/665582 AU - Monin, D. AU - Bohlender, D. AU - Hardy, T. AU - Saddlemyer, L. AU - Fletcher, M. T2 - Publications of the Astronomical Society of the Pacific SN - 0004-6280 VL - 124 IS - 914 SP - 329 EP - 342 AB - A new, inexpensive polarimetric unit has been constructed for the Dominion Astrophysical Observatory (DAO) 1.8 m Plaskett telescope. It is implemented as a plug-in module for the telescope's existing Cassegrain spectrograph, and it enables medium-resolution (R≈10,000) circular spectropolarimetry of point sources. A dual-beam design, together with fast switching of the wave plate at rates up to 100 Hz and synchronized with charge shuffling on the CCD, is used to significantly reduce instrumental effects and achieve high-precision spectropolarimetric measurements for a very low cost. The instrument is optimized to work in the wavelength range of 4700-5300 Å to simultaneously detect polarization signals in the Hβ line, as well as nearby metallic lines. In this article we describe the technical details of the instrument, our observing strategy, and data reduction techniques, and we present tests of its scientific performance. © 2012. The Astronomical Society of the Pacific. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 71758af4-d58a-4d21-a27f-dc0687067c3d ER - TY - JOUR TI - RILEM TC 203-RHM: Repair mortars for historic masonry: Ments for repointing mortars for historic masonry DO - 10.1617/s11527-012-9849-7 AU - Maurenbrecher, P. T2 - Materials and Structures/Materiaux et Constructions SN - 1359-5997 VL - 45 IS - 9 SP - 1303 EP - 1309 KW - Historic masonry KW - Masonry KW - Performance requirements KW - Repointing KW - Conservation KW - Repair KW - Mortar AB - This paper gives a summary of functional and performance requirements for repointing mortars for historic masonry (design, execution and maintenance). Successful performance of repair and conservation of mortar in historic masonry requires more care with design and execution than with modern masonry. © 2012 RILEM. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d8a8f4f8-e019-46cd-a702-bd1724e08a14 ER - TY - JOUR TI - Self-priming of liquids in capillary autonomous microfluidic systems DO - 10.1007/s10404-011-0881-7 AU - Clime, L. AU - Brassard, D. AU - Pezacki, J.P. AU - Veres, T. T2 - Microfluidics and Nanofluidics SN - 1613-4982 VL - 12 IS - 1-Apr SP - 371 EP - 382 KW - 3-D microfluidic KW - Air bubbles KW - Autonomous systems KW - Biological fluids KW - Capillary rise KW - Complete wetting KW - Complex 3D geometry KW - Contact line dynamics KW - Critical parameter KW - Geometrical optimization KW - Lattice Boltzmann method KW - Liquid gas interface KW - Liquid solids KW - Liquid water KW - Micro fluidic system KW - Micro-chambers KW - Micro-fluidic devices KW - Microfluidic cavity KW - Microfluidic channel KW - Numerical approaches KW - Numerical models KW - Numerical results KW - Parallel implementations KW - Performance criterion KW - Physical process KW - Quantitative effects KW - Rectangular cavity KW - Self-priming KW - Target regions KW - Capillary flow KW - Contact angle KW - Dynamics KW - Fluidic devices KW - Liquids KW - Numerical methods KW - Optimization KW - Phase interfaces KW - Three dimensional KW - Wetting KW - Microfluidics AB - We present a numerical approach to the capillary rise dynamics in microfluidic channels of complex 3D geometries. In order to optimize the delivery of specific biological fluids to target regions in microfluidic capillary autonomous systems (CAS), we analyze self-priming of liquid water into a microfluidic device consisting of a microfluidic channel that feeds a rectangular microfluidic cavity trough an appropriately designed micro-chamber. The target performance criteria in our optimization are (1) fast and complete wetting of the cavity bottom while (2) minimizing the probability of trapping air bubble in the device. The numerical model is based on the lattice Boltzmann method (LBM) and a three-dimensional single-component multiple-phase (SCMP) scheme. By using a parallel implementation of this algorithm, we investigate the physical processes related to the invasion of the liquid-gas interfaces in rectangular cavities at different liquid-solid contact angle and shapes of the transition micro-chamber. The numerical results has successfully captured important qualitative and some key quantitative effects of the liquid-solid contact angle, the roughness of the cavity edges, the depth of the holes and shape of the micro-chambers. Moreover, we present and validate experimentally simple geometrical optimizations of the microfluidic device that ensure the complete filling the microfluidic cavity with liquid. Critical parameters related to the overall priming time of the device are presented as well. © 2011 Crown Copyright as represented by the National Research Council. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5bc506ac-d294-43f8-973d-b8c60af3a295 ER - TY - JOUR TI - Role of macrophages in early host resistance to respiratory Acinetobacter baumannii infection DO - 10.1371/journal.pone.0040019 AU - Qiu, H. AU - KuoLee, R AU - Harris, G AU - Van Rooijen, N AU - Patel, G.B AU - Chen, W T2 - PloS one SN - 1932-6203 VL - 7 IS - 6 SP - e40019 KW - Macrophages; Bacterial pathogens; Respiratory infections; Neutrophils; Alveolar macrophages; Cytokines; Nitric oxide; Phagocytosis AB - Acinetobacter baumannii is an emerging bacterial pathogen that causes nosocomial pneumonia and other infections. Although it is recognized as an increasing threat to immunocompromised patients, the mechanism of host defense against A. baumannii infection remains poorly understood. In this study, we examined the potential role of macrophages in host defense against A. baumannii infection using in vitro macrophage culture and the mouse model of intranasal (i.n.) infection. Large numbers of A. baumannii were taken up by alveolar macrophages in vivo as early as 4 h after i.n. inoculation. By 24 h, the infection induced significant recruitment and activation (enhanced expression of CD80, CD86 and MHC-II) of macrophages into bronchoalveolar spaces. In vitro cell culture studies showed that A. baumannii were phagocytosed by J774A.1 (J774) macrophage-like cells within 10 minutes of co-incubation, and this uptake was microfilament- and microtubule-dependent. Moreover, the viability of phagocytosed bacteria dropped significantly between 24 and 48 h after co-incubation. Infection of J774 cells by A. baumannii resulted in the production of large amounts of proinflammatory cytokines and chemokines, and moderate amounts of nitric oxide (NO). Prior treatment of J774 cells with NO inhibitors significantly suppressed their bactericidal efficacy (P<0.05). Most importantly, in vivo depletion of alveolar macrophages significantly enhanced the susceptibility of mice to i.n. A. baumannii challenge (P<0.01). These results indicate that macrophages may play an important role in early host defense against A. baumannii infection through the efficient phagocytosis and killing of A. baumannii to limit initial pathogen replication and the secretion of proinflammatory cytokines and chemokines for the rapid recruitment of other innate immune cells such as neutrophils. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : be1fa83f-c9a8-4aa8-822e-0e2026c491be ER - TY - JOUR TI - Helicobacter pylori isolates from Greek children express type 2 and type 1 Lewis and α1, 6-glucan antigens in conjunction with a functional type IV secretion system DO - 10.1099/jmm.0.038729-0 AU - Altman, E. AU - Chandan, V. AU - Harrison, B.A. AU - Panayotopoulou, E.G. AU - Roma-Giannikou, E. AU - Li, J. AU - Sgouras, D.N. T2 - Journal of Medical Microbiology SN - 0022-2615 VL - 61 IS - 4 SP - 559 EP - 566 KW - alpha1,6 glucan antigen KW - CagA protein KW - epitope KW - glucan KW - unclassified drug KW - adolescent KW - article KW - bacterial strain KW - bacterium isolate KW - child KW - enzyme linked immunosorbent assay KW - gel electrophoresis KW - Greece KW - Helicobacter infection KW - Helicobacter pylori KW - human KW - human tissue KW - immunoblotting KW - nonhuman KW - pathogenicity KW - pediatrics KW - preschool child KW - priority journal KW - school child KW - Adolescent KW - Antigens, Bacterial KW - Bacterial Proteins KW - Child KW - Child, Preschool KW - Gastric Mucosa KW - Gene Expression Regulation, Bacterial KW - Glucans KW - Greece KW - Helicobacter Infections KW - Helicobacter pylori KW - Humans KW - Lewis Blood-Group System AB - Helicobacter pylori infection is often acquired in childhood and can persist for life. Previous studies in adult patients have shown that H. pylori isolates from North American and European hosts express predominantly type 2 Lewis x (Le x) and Le y epitopes, while Asian strains have the capacity to express type 1 Le a and Le b structures. In order to understand the influence of environmental and host factors on the expression of Le antigens, we analysed 50 Greek H. pylori isolates from symptomatic children. Both CagA-positive and-negative strains were evaluated. The expression of Le antigens was determined by whole-cell indirect ELISA (WCE), and LPS profiles were assessed by gel electrophoresis and immunoblotting. Occurrence of Le x and/or Ley antigens was confirmed in 35 of the isolates (70 %) while 15 of the isolates were non-typable. It was found that 11 of the paediatric isolates had the propensity to express type 1 Le b blood-group antigen (22 %), a feature relatively uncommon in H. pylori isolates from adults. One strain expressed both Le b and Le a antigens. The majority of the isolates (49/50, 98 %) expressed α1,6-glucan, an antigenic non-Le determinant present in the outer core region of H. pylori LPS. All Le x-and Leyexpressing strains also carried a functional cag pathogenicity island-encoding a type IV secretion system, capable of translocating CagA protein, as well as the vacAs1 allele, suggesting that Le x and Ley epitopes may aid the persistence of more aggressive strains. No association between bacterial virulence characteristics and the histopathological observations was evident. © 2012 National Research Council of Canada. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f2cf38b0-cf70-4dd1-a788-a78e04a9efa9 ER - TY - JOUR TI - Clustering properties of BzK-selected galaxies in goods-N: Environmental quenching and triggering of star formation at z 2 DO - 10.1088/0004-637X/756/1/71 AU - Lin, L. AU - Dickinson, M. AU - Jian, H.-Y. AU - Merson, A.I. AU - Baugh, C.M. AU - Scott, D. AU - Foucaud, S. AU - Wang, W.-H. AU - Yan, C.-H. AU - Yan, H.-J. AU - Cheng, Y.-W. AU - Guo, Y. AU - Helly, J. AU - Kirsten, F. AU - Koo, D.C. AU - Lagos, C.D.P. AU - Meger, N. AU - Messias, H. AU - Pope, A. AU - Simard, L. AU - Grogin, N.A. AU - Wang, S.-Y. T2 - The Astrophysical Journal SN - 0004-637X VL - 756 IS - 1 SP - 71 AB - Using a sample of BzK-selected galaxies at z ∼ 2 identified from the CFHT/WIRCAM near-infrared survey of GOODS-North, we discuss the relation between star formation rate (SFR), specific star formation rate (SSFR), and stellar mass (M *), and the clustering of galaxies as a function of these parameters. For star-forming galaxies (sBzKs), the UV-based SFR, corrected for extinction, scales with the stellar mass as SFRM α * with α = 0.74 ± 0.20 down to M * 10 9 M ⊙, indicating a weak dependence on the stellar mass of the SFR efficiency, namely, SSFR. We also measure the angular correlation function and hence infer the correlation length for sBzK galaxies as a function of M *, SFR, and SSFR, as well as K-band apparent magnitude. We show that passive galaxies (pBzKs) are more strongly clustered than sBzK galaxies at a given stellar mass, mirroring the color-density relation seen at lower redshifts. We also find that the correlation length of sBzK galaxies ranges from 4 to 20h -1Mpc, being a strong function of M K , M *, and SFR. On the other hand, the clustering dependence on SSFR changes abruptly at 2 × 10 -9yr -1, which is the typical value for "main-sequence" star-forming galaxies at z ∼ 2. We show that the correlation length reaches a minimum at this characteristic value, and is larger for galaxies with both smaller and larger SSFRs; a dichotomy that is only marginally implied from the predictions of the semi-analytical models. Our results suggest that there are two types of environmental effects at work at z ∼ 2. Stronger clustering for relatively quiescent galaxies implies that the environment has started to play a role in quenching star formation. At the same time, stronger clustering for galaxies with elevated SSFRs (" starbursts") might be attributed to an increased efficiency for galaxy interactions and mergers in dense environments. © © 2012. The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e9bf2e6f-31c9-46b2-933d-8aff1d88f676 ER - TY - JOUR TI - Third component search and abundances of the very dusty short-period binary BD +20°307 DO - 10.1088/0004-637X/749/1/7 AU - Fekel, F.C. AU - Cordero, M.J. AU - Galicher, R. AU - Zuckerman, B. AU - Melis, C. AU - Weinberger, A.J. T2 - The Astrophysical Journal SN - 0004-637X VL - 749 IS - 1 SP - 7 AB - We have obtained near-infrared adaptive optics imaging and collected additional radial velocity observations to search for a third component in the extremely dusty short-period binary system BD +20°307. Our image shows no evidence for a third component at separations greater than 19AU. Our four seasons of radial velocities have a constant center-of-mass velocity and are consistent with the systemic velocities determined at two earlier epochs. Thus, the radial velocities also provide no support for a third component. Unfortunately, the separation domains covered by our imaging and radial velocity results do not overlap. Thus, we examined the parameters for possible orbits of a third component that could have been missed by our current observations. With our velocities we determined improved circular orbital elements for the 3.4 day double-lined binary. We also performed a spectroscopic abundance analysis of the short-period binary components and conclude that the stars are a mid- and a late-F dwarf. We find that the iron abundances of both components, [Fe/H] = 0.15, are somewhat greater than the solar value and comparable to that of stars in the Hyades. Despite the similarity of the binary components, the lithium abundances of the two stars are very unequal. The primary has log ε (Li) = 2.72, while in the secondary log ε (Li)≤1.46, which corresponds to a difference of at least a factor of 18. The very disparate lithium abundances in very similar stars make it impossible to ascribe a single age to them. While the system is likely at least 1Gyr old, it may well be as old as the Sun. © 2012 The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3c8ec963-db4c-4486-8834-883e454ba0bd ER - TY - JOUR TI - Tribological behaviors of titanium nitride-and chromium-nitride-based physical vapor deposition coating systems DO - 10.1115/1.4007168 AU - Cai, F. AU - Huang, X. AU - Yang, Q. AU - Nagy, D. T2 - Journal of Engineering for Gas Turbines and Power SN - 0742-4795 VL - 134 IS - 11 SP - 112504 KW - Cathodic arc KW - Coated sample KW - Coating compositions KW - Coefficient of frictions KW - CrN-based coatings KW - Deposition process KW - Erosion behavior KW - Erosion rates KW - Erosion resistance KW - Impingement angle KW - Micro-structural KW - Physical vapor deposition coatings KW - Plasma enhanced magnetron sputtering KW - Tribological behaviors KW - Tribological properties KW - Wear rates KW - Young's Modulus KW - Amorphous films KW - Chromium KW - Elastic moduli KW - Electron beams KW - Friction KW - Hardness KW - Microstructure KW - Protective coatings KW - Titanium nitride KW - Tribology KW - Erosion AB - This study investigates the effects of the deposition process and coating composition on microstructural and tribological properties of TiN-and CrN-based coating systems. Coatings were produced using various PVD-based processes-electron beam (EB), cathodic arc (CA), and plasma enhanced magnetron sputtering (PEMS). All coated samples were evaluated for their composition, microstructure, and surface morphology. Coating mechanical properties such as hardness, Young's modulus, and coefficient of friction were also studied and related to their microstructures, wear, and erosion resistances. It was found that hardness (H), Young's modulus (E), and coefficient of friction had impact on both wear and erosion rates. In particular, the H 3/E 2 ratio was inversely proportional to the specific wear rate. For erosion behavior, higher H 3/E 2 ratios relate to lower erosion rates at low impingement angles, whereas higher H 3/E 2 ratios relate to higher erosion rates at high impingement angles. © 2012 American Society of Mechanical Engineers. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 74bde919-179b-4de6-8111-22f0f0b073a3 ER - TY - JOUR TI - Dilution effects on partially-premixed combustion of an ultra-low sulphur diesel fuel under low-load operation DO - 10.1115/ICES2012-81236 AU - Dumitrescu, C.E. AU - Neill, W.S. AU - Guo, H. AU - Chippior, W.L. T2 - Proceedings of the Spring Technical Conference of the ASME Internal Combustion Engine Division T3 - ASME 2012 Internal Combustion Engine Division Spring Technical Conference, ICES 2012, 6 May 2012 through 9 May 2012, Torino, Piemonte SN - 1529-6598 SN - 9780791844663 SP - 405 EP - 414 KW - Charge dilution KW - Combustion duration KW - Combustion performance KW - Exhaust gas recirculation (EGR) KW - Heavy-duty diesel engine KW - Oxygen concentrations KW - Partially-premixed KW - Start of injections KW - Combustion KW - Diesel engines KW - Diesel fuels KW - Fuel injection KW - Optimization KW - Oxygen KW - Sulfur KW - Dilution AB - Dilution of partially-premixed combustion (PPC) using different combinations of excess air (λ>1) and exhaust gas recirculation (EGR) was investigated in a single-cylinder, heavy-duty diesel engine equipped with common-rail fuel injection. The experiments were limited to a single fuel injection event using ultra-low sulphur diesel fuel at a low engine load (∼3 bar BMEP) and engine speeds of 900 and 1350 rpm. The start of injection was varied to optimize the combustion performance and emissions. The experimental results show that increasing air dilution at constant EGR reduced BSFC slightly. CO and HC emissions decreased significantly due to the increased oxygen concentration, but NOx and soot emissions increased. For a given level of charge dilution, there was an optimal EGR rate to minimize BSFC. NOx emissions decreased significantly as the proportion of dilution by EGR was increased, but CO and HC emissions increased due to the reduced in-cylinder temperature and oxygen concentration, which increased the combustion duration. Copyright © 2012 by Her Majesty the Queen in Right of Canada. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 33261800-bbd7-4809-ad13-03dc24ae801b ER - TY - JOUR TI - The ACS LCIS project. VII. the blue stragglers population in the isolated dSph galaxies Cetus and Tucana DO - 10.1088/0004-637X/744/2/157 AU - Monelli, M. AU - Cassisi, S. AU - Mapelli, M. AU - Bernard, E.J. AU - Aparicio, A. AU - Skillman, E.D. AU - Stetson, P.B. AU - Gallart, C. AU - Hidalgo, S.L. AU - Mayer, L. AU - Tolstoy, E. T2 - The Astrophysical Journal SN - 0004-637X VL - 744 IS - 2 SP - 157 AB - We present the first investigation of the Blue Straggler star (BSS) population in two isolated dwarf spheroidal galaxies of the Local Group, Cetus and Tucana. Deep Hubble Space Telescope/Advanced Camera for Surveys photometry allowed us to identify samples of 940 and 1214 candidates, respectively. The analysis of the star formation histories of the two galaxies suggests that both host a population of BSSs. Specifically, if the BSS candidates are interpreted as young main sequence stars, they do not conform to their galaxy's age-metallicity relationship. The analysis of the luminosity function and the radial distributions supports this conclusion, and suggests a non-collisional mechanism for the BSS formation, from the evolution of primordial binaries. This scenario is also supported by the results of new dynamical simulations presented here. Both galaxies coincide with the relationship between the BSS frequency and the absolute visual magnitude MV found by Momany etal. If this relationship is confirmed by larger sample, then it could be a valuable tool to discriminate between the presence of BSSs and galaxies hosting truly young populations. © 2012 The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8545ae5f-5465-42c9-a73d-ea0355999612 ER - TY - JOUR TI - Early-type galaxies at z ∼ 1.3. IV. Scaling relations in different environments DO - 10.1088/0004-637X/745/2/130 AU - Raichoor, A. AU - Mei, S. AU - Stanford, S.A. AU - Holden, B.P. AU - Nakata, F. AU - Rosati, P. AU - Shankar, F. AU - Tanaka, M. AU - Ford, H. AU - Huertas-Company, M. AU - Illingworth, G. AU - Kodama, T. AU - Postman, M. AU - Rettura, A. AU - Blakeslee, J.P. AU - Demarco, R. AU - Jee, M.J. AU - White, R.L. T2 - The Astrophysical Journal SN - 0004-637X VL - 745 IS - 2 SP - 130 AB - We present the Kormendy and mass-size relations (MSR) for early-type galaxies (ETGs) as a function of environment at z ∼ 1.3. Our sample includes 76 visually classified ETGs with masses 10 10 < M/M Ȯ < 10 11.5, selected in the Lynx supercluster and in the Great Observatories Origins Deep Survey/Chandra Deep Field South field; 31 ETGs in clusters, 18 in groups, and 27 in the field, all with multi-wavelength photometry and Hubble Space Telescope/Advanced Camera for Surveys observations. The Kormendy relation, in place at z 1.3, does not depend on the environment. The MSR reveals that ETGs overall appear to be more compact in denser environments: cluster ETGs have sizes on average around 30%-50% smaller than those of the local universe and a distribution with a smaller scatter, whereas field ETGs show an MSR with a similar distribution to the local one. Our results imply that (1) the MSR in the field did not evolve overall from z ∼ 1.3 to present; this is interesting and in contrast to the trend found at higher masses from previous works; (2) in denser environments, either ETGs have increased in size by 30%-50% on average and spread their distributions, or more ETGs have been formed within the dense environment from non-ETG progenitors, or larger galaxies have been accreted to a pristine compact population to reproduce the MSR observed in the local universe. Our results are driven by galaxies with masses M ≲ 2 × 10 11 M Ȯ and those with masses M ∼ 10 11 M Ȯ follow the same trends as that of the entire sample. Following the Valentinuzzi et al. definition of superdense ETGs, ∼ 35%-45% of our cluster sample is made up of superdense ETGs. © 2012. The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a8b3514d-4948-4428-bbcf-83997118c053 ER - TY - JOUR TI - Molecular line contamination in the SCUBA-2 450 and 850 μm continuum data DO - 10.1111/j.1365-2966.2012.21140.x AU - Drabek, E. AU - Hatchell, J. AU - Friberg, P. AU - Richer, J. AU - Graves, S. AU - Buckle, J.V. AU - Nutter, D. AU - Johnstone, D. AU - Di Francesco, J. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 426 IS - 1 SP - 23 EP - 39 AB - Observations of the dust emission using millimetre/submillimetre bolometer arrays can be contaminated by molecular line flux, such as flux from 12CO. As the brightest molecular line in the submillimetre, it is important to quantify the contribution of CO flux to the dust continuum bands. Conversion factors were used to convert molecular line integrated intensities to flux detected by bolometer arrays in mJybeam -1. These factors were calculated for 12CO line integrated intensities to the SCUBA-2 850 and 450μm bands. The conversion factors were then applied to HARP 12CO 3-2 maps of NGC 1333 in the Perseus complex and NGC 2071 and NGC 2024 in the Orion B molecular cloud complex to quantify the respective 12CO flux contribution to the 850μm dust continuum emission. Sources with high molecular line contamination were analysed in further detail for molecular outflows and heating by nearby stars to determine the cause of the 12CO contribution. The majority of sources had a 12CO 3-2 flux contribution under 20per cent. However, in regions of molecular outflows, the 12CO can dominate the source dust continuum (up to 79per cent contamination) with 12CO fluxes reaching ∼68mJybeam -1. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 84b8e239-e6ed-4c3c-a8e0-bae2591508c9 ER - TY - JOUR TI - Doubled haploidy as a tool in ornamental breeding AU - Ferrie, A.M.R. T2 - Acta Horticulturae SN - 0567-7572 SN - 9789066054172 VL - 953 SP - 167 EP - 172 AB - Haploidy/doubled haploidy methodology is commonly used in many agronomically important crops to speed the development of new cultivars. There are a number of advantages in using haploidy technology in both practical application (varietal development, mutagenesis, transformation) and basic research (genomics, biochemical, and physiological studies). Haploid plants are commonly produced using one of four methods: culture of anthers or microspores (androgenesis), culture of unfertilized ovules (gynogenesis), interspecific or intergeneric crosses followed by chromosome elimination, and by pollination with irradiated pollen. The most efficient method depends on the species. In many species, the culture of isolated microspores or anthers is the most frequently used method of haploid production. With this method, every microspore is potentially capable of regenerating into a viable embryo and each plant would therefore represent the variation which exists in the population of microspores. Plant regeneration occurs either by direct embryogenesis or through callus formation followed by embryogenesis or organogenesis. There are a number of factors influencing embryogenesis from anther/microspores or ovaries/ovules including genotype, donor plant growth conditions, stage of explant development, composition of the culture medium, and environmental conditions during culture. The frequency of embryo production will depend on whether or not these conditions are optimal and varies depending on the species. Compared to some agronomic species, there has been very little work on doubled haploidy in ornamental species despite the potential benefits. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 36a0c188-7743-4d85-a163-46b21fe2c8d6 ER - TY - JOUR TI - Instantaneous spectroscopic SS-OCT imaging using a simultaneous dual-band swept laser and common-path fiber probe DO - 10.1117/12.974738 AU - Mao, Y. AU - Chang, S. AU - Flueraru, C. AU - Murdock, E. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - 22nd International Conference on Optical Fiber Sensors, 15 October 2012 through 19 October 2012, Beijing SN - 0277-786X SN - 9780819491039 VL - 8421 SP - 84215O KW - Common-path interferometers KW - Dual-window polygonal KW - Fiber probe KW - Grin fibers KW - Spectroscopic contrast KW - Swept source KW - Swept source optical coherence tomographies KW - Fibers KW - Probes KW - Optical tomography AB - A simultaneous 1310/1550 swept-source optical coherence tomography system is implemented by combining a novel dual-band swept laser source and an integrated common-path GRIN lensed fiber interferometer/probe. Highspeed synchronized dual-wavelength tuning is performed by using two laser cavities with a single dual-window polygonal. Simultaneous in vivo OCT imaging at 1310 and 1550 nm is demonstrated. This dual-band technique bring together common-path fiber probe potentially allows instantaneous in situ functional OCT imaging with high quality spectroscopic contrast and stable phase measurements. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 282cca95-2619-4b9f-92c5-db602597076c ER - TY - JOUR TI - Load monitoring of aerospace structures utilizing micro-electro-mechanical systems for static and quasi-static loading conditions DO - 10.1088/0964-1726/21/11/115001 AU - Martinez, M. AU - Rocha, B. AU - Li, M. AU - Shi, G. AU - Beltempo, A. AU - Rutledge, R. AU - Yanishevsky, M. T2 - Smart Materials and Structures SN - 0964-1726 VL - 21 IS - 11 SP - 115001 KW - Aerospace structure KW - Aluminum beams KW - Aluminum skin KW - Angle estimation KW - Applied strain KW - Displacement curve KW - Finite element models KW - Fourth order KW - Linear variable displacement transducers KW - Load monitoring KW - Load monitoring systems KW - Loading condition KW - Micro electro mechanical system KW - National Research Council KW - Polynomial surface KW - Quasi-static loading KW - Sensor systems KW - Shear loads KW - Structural complexity KW - Test platforms KW - Wing structures KW - Aluminum KW - Estimation KW - Finite element method KW - MEMS KW - Stringers KW - Transducers KW - Loading AB - The National Research Council Canada (NRC) has worked on the development of structural health monitoring (SHM) test platforms for assessing the performance of sensor systems for load monitoring applications. The first SHM platform consists of a 5.5m cantilever aluminum beam that provides an optimal scenario for evaluating the ability of a load monitoring system to measure bending, torsion and shear loads. The second SHM platform contains an added level of structural complexity, by consisting of aluminum skins with bonded/riveted stringers, typical of an aircraft lower wing structure. These two load monitoring platforms are well characterized and documented, providing loading conditions similar to those encountered during service. In this study, a micro-electro-mechanical system (MEMS) for acquiring data from triads of gyroscopes, accelerometers and magnetometers is described. The system was used to compute changes in angles at discrete stations along the platforms. The angles obtained from the MEMS were used to compute a second, third or fourth order degree polynomial surface from which displacements at every point could be computed. The use of a new Kalman filter was evaluated for angle estimation, from which displacements in the structure were computed. The outputs of the newly developed algorithms were then compared to the displacements obtained from the linear variable displacement transducers connected to the platforms. The displacement curves were subsequently post-processed either analytically, or with the help of a finite element model of the structure, to estimate strains and loads. The estimated strains were compared with baseline strain gauge instrumentation installed on the platforms. This new approach for load monitoring was able to provide accurate estimates of applied strains and shear loads. © 2012 IOP Publishing Ltd. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2ca87f7a-9b36-4d4d-a465-accf703a652b ER - TY - JOUR TI - Collisional evolution of ultra-wide trans-neptunian binaries DO - 10.1088/0004-637X/744/2/139 AU - Parker, A.H. AU - Kavelaars, J.J. T2 - The Astrophysical Journal SN - 0004-637X VL - 744 IS - 2 SP - 139 AB - The widely separated, near-equal mass binaries hosted by the cold classical Kuiper Belt are delicately bound and subject to disruption by many perturbing processes. We use analytical arguments and numerical simulations to determine their collisional lifetimes given various impactor size distributions and include the effects of mass loss and multiple impacts over the lifetime of each system. These collisional lifetimes constrain the population of small (R ≳ 1km) objects currently residing in the Kuiper Belt and confirm that the size distribution slope at small size cannot be excessively steep - likely q ≲ 3.5. We track mutual semimajor axis, inclination, and eccentricity evolution through our simulations and show that it is unlikely that the wide binary population represents an evolved tail of the primordially tight binary population. We find that if the wide binaries are a collisionally eroded population, their primordial mutual orbit planes must have preferred to lie in the plane of the solar system. Finally, we find that current limits on the size distribution at small radii remain high enough that the prospect of detecting dust-producing collisions in real time in the Kuiper Belt with future optical surveys is feasible. © 2012. The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c417ddb2-769d-4bb9-bc6f-2cc63f3493ce ER - TY - JOUR TI - Comparison of experimental and numerical results for the quasi-static and dynamic tensile behaviour of a commercial Ti6Al4V alloy as a function of initial crystallographic texture DO - 10.4028/www.scientific.net/MSF.706-709.723 AU - Coghe, F. AU - Tirry, W. AU - Peirs, J. AU - Verleysen, P. AU - Dalgaard, E. AU - Wanjara, P. AU - Rabet, L. AU - Van Houtte, P. T2 - Materials Science Forum T3 - 7th International Conference on Processing and Manufacturing of Advanced Materials, THERMEC'2011, 1 August 2011 through 5 August 2011, Quebec City, QC SN - 0255-5476 SN - 9783037853030 VL - 706-709 SP - 723 EP - 728 KW - Active deformation KW - Base material KW - Crystal plasticity KW - Crystallographic textures KW - High strain rates KW - Linear friction welding KW - Mechanical behaviour KW - Numerical results KW - Quasi-static KW - Quasi-static tensile test KW - SHPB KW - Split Hopkinson bar KW - Tensile behaviour KW - Ti-6al-4v KW - Ti-6Al-4V alloy KW - Visco-plastic self-consistent KW - VPSC KW - Bars (metal) KW - Strain rate KW - Tensile testing KW - Textures KW - Titanium KW - Twinning KW - Experiments KW - Experiments KW - Twinning AB - Quasi-static tensile tests and high strain rate split Hopkinson bar tensile experiments were used to mechanically characterize a commercially available Ti6Al4V alloy. The material was tested along different directions as to assess the influence of the initial crystallographic texture on the mechanical behaviour. In order to circumvent the problem of the limited thickness of the base material, special usage was made of the Linear Friction Welding technique. The results of the experiments were afterwards compared to the numerical results of a crystal plasticity code based on the viscoplastic self-consistent approach, taking into account twinning as an active deformation mode. © 2012 Trans Tech Publications, Switzerland. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c5e7ddff-fdd8-44bb-a597-dfb029e918c1 ER - TY - JOUR TI - Shape from suggestive contours using 3D priors DO - 10.1109/CRV.2012.38 AU - Wuhrer, Stefanie AU - Shu, Chang T2 - 2012 Ninth Conference on Computer and Robot Vision (CRV) T3 - 2012 9th Conference on Computer and Robot Vision, CRV 2012, May 28-30, 2012, Toronto, ON, Canada SN - 9780769546834 SN - 978-1-4673-1271-4 SP - 6233147 SP - 236 EP - 243 KW - Deformable object KW - Functional mapping KW - Non-Photorealistic Rendering KW - Shape inference KW - statistical priors KW - suggestive contours KW - Synthetic experiments KW - Three-dimensional shape KW - Computer graphics KW - Drawing (graphics) KW - Experiments KW - Forecasting KW - Photography KW - Computer vision AB - This paper introduces an approach to predict the three-dimensional shape of an object belonging to a specific class of shapes shown in an input image. We use suggestive contour, a shape-suggesting image feature developed in computer graphics in the context of non-photorealistic rendering, to reconstruct 3D shapes. We learn a functional mapping from the shape space of suggestive contours to the space of 3D shapes and use this mapping to predict 3D shapes based on a single input image. We demonstrate that the method can be used to predict the shape of deformable objects and to predict the shape of human faces using synthetic experiments and experiments based on artist drawn sketches and photographs. DA - 2012 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f392a5eb-7160-4b97-bf61-ca940afe30a4 ER - TY - JOUR TI - Effect of n-CaCO 3 and metakaolin on hydrated Portland cement DO - 10.1680/adcr.11.00010 AU - Makar, J.M. AU - Beaudoin, J.J. AU - Trischuk, K. AU - Chan, G.W. AU - Torres, F. T2 - Advances in Cement Research SN - 0951-7197 VL - 24 IS - 4 SP - 211 EP - 219 KW - Binary blends KW - Control samples KW - Ettringites KW - Hydration activity KW - Isothermal conduction calorimetries KW - Metakaolins KW - Nanoparticle addition KW - Ordinary Portland cement KW - Secondary phase KW - Secondary phasis KW - Supplementary cementing materials KW - Ternary blends KW - Calcium carbonate KW - Nanoparticles KW - Portland cement KW - Thermogravimetric analysis KW - X ray diffraction KW - Hydration AB - The effect of calcium carbonate nanoparticles (nCaCO 3) on the hydration of ordinary Portland cement (OPC) blended with metakaolin was studied through comparison with OPC, OPC plus metakaolin and OPC plus nCaCO 3 control samples. Isothermal conduction calorimetry measurements showed that the hydration of the ternary OPC-metakaolin-nCaCO 3 blend had pronounced early secondary phase hydration activity compared to the controls. X-ray diffraction and thermogravimetric analysis identified the phases as calcium aluminosulfates, with both ettringite and monosulfate forming more quickly in the ternary blend than in the other samples. The presence of the nCaCO 3 also enhanced the formation of C 3A. CaCO 3. 12H 2O in both blends that contained it. The presence of the secondary phases or the nCaCO 3 itself was associated with a significant reduction in strength in the ternary blend as compared to the OPC-metakaolin binary blend. The results suggest that caution is needed in the development of concrete with nanoparticle additions in order to avoid detrimental combinations of nanoparticles, OPC and supplementary cementing materials. © 2012 Thomas Telford Ltd. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5f7b9a6d-ff52-4f5b-8c60-6c68c7b877c3 ER - TY - JOUR TI - Lack of functional selectin ligand interactions compromises long term tumor protection by CD8 + T cells DO - 10.1371/journal.pone.0032211 AU - Stark, F.C. AU - Gurnani, K. AU - Sad, S. AU - Krishnan, L. T2 - PLoS ONE SN - 1932-6203 VL - 7 IS - 2 SP - e32211 KW - bacterial vaccine KW - gamma interferon KW - selectin KW - tumor antigen KW - fucosyltransferase KW - ligand KW - ovalbumin KW - selectin KW - animal cell KW - animal experiment KW - animal model KW - article KW - cancer prevention KW - CD8+ T lymphocyte KW - cell infiltration KW - cell migration KW - cell proliferation KW - cellular immunity KW - controlled study KW - dendritic cell KW - in vivo study KW - Listeria monocytogenes KW - lymphocyte function KW - mouse KW - nonhuman KW - phenotype KW - protein determination KW - protein expression KW - protein function KW - protein localization KW - protein protein interaction KW - tumor growth KW - tumor immunity KW - tumor xenograft KW - wild type KW - animal KW - antigen presentation KW - immunology KW - mouse mutant KW - neoplasm KW - Animals KW - Antigen Presentation KW - CD8-Positive T-Lymphocytes KW - Fucosyltransferases KW - Ligands KW - Mice KW - Mice, Knockout KW - Neoplasms KW - Ovalbumin KW - Selectins AB - Central memory CD8 + T cells expressing the adhesion molecule CD62L (L-selectin) are potent mediators of anti-cancer immunity due to their ability to proliferate extensively upon antigen re-stimulation. The interaction of selectin with its ligands mediates leukocyte rolling along high endothelial venules. Mice deficient in α(1,3) Fucosyltransferase IV and VII (FtDKO) lack functional L, P and E selectin ligands. Thus, we addressed whether the lack of selectin ligand interactions alters tumor protection by CD8 + T cells in FtDKO mice. Listeria monocytogenes-OVA (LM-OVA) infection evoked potent OVA-specific CD8 + T cells that proliferated and contracted at similar kinetics and phenotype in FtDKO and wild-type mice. Additionally, OVA-specific CD8 + T cells in both mouse strains exhibited similar phenotypic differentiation, in vivo cytolytic activity and IFN-γ expression. However, FtDKO mice succumbed to B16-OVA tumors significantly earlier than wild-type mice. In contrast, FtDKO mice evoked strong recall memory CD8 + T cell responses and protection to systemic LM-OVA re-challenge. The diminished tumor protection in FtDKO mice was not related to defective antigen presentation by dendritic cells or reduced proliferation of antigen-specific CD8 + T cells. However, WT or FtDKO OVA-specific CD8 + T cells showed significantly reduced ability to traffic to lymph nodes upon adoptive transfer into naïve FtDKO recipients. Furthermore, FtDKO OVA-specific CD8 + T cells displayed poor ability to infiltrate tumors growing in WT mice. These results reveal that selectin ligand expression on host endothelium as well CD8 + T cells may be important for their efficient and continued extravasation into peripheral tumors. © 2012 Stark et al. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0a3dfeaa-b4d3-4bde-bf82-e7a66eed9050 ER - TY - JOUR TI - Globular cluster systems of early-type galaxies in low-density environments DO - 10.1111/j.1365-2966.2012.20873.x AU - Cho, J. AU - Sharples, R.M. AU - Blakeslee, J.P. AU - Zepf, S.E. AU - Kundu, A. AU - Kim, H.-S. AU - Yoon, S.-J. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 422 IS - 4 SP - 3591 EP - 3610 AB - Deep images of 10 early-type galaxies in low-density environments have been obtained with the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope. The global properties of the globular cluster (GC) systems of the galaxies have been derived in order to investigate the role of the environment in galaxy formation and evolution. Using the ACS Virgo Cluster Survey as a high-density counterpart, the similarities and differences between the GC properties in high- and low-density environments are presented. We find a strong correlation of the GC mean colours and the degree of colour bimodality with the host galaxy luminosity in low-density environments, in good agreement with high-density environments. In contrast, the GC mean colours at a given host luminosity are somewhat bluer [Δ(g-z) ∼ 0.05] than those for cluster galaxies, indicating more metal poor (Δ[Fe/H] ∼ 0.10 - 0.15) and/or younger (Δage > 2 Gyr) GC systems than those in dense environments. Furthermore, with decreasing host luminosity, the colour bimodality disappears faster, when compared to galaxies in cluster environments. Our results suggest that: (1) in both high- and low-density environments, the mass of the host galaxy has the dominant effect on GC system properties; (2) the local environment has only a secondary effect on the history of GC system formation; and (3) GC formation must be governed by common physical processes across a range of environments. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0a9da23b-0488-4e10-9967-e3dab29b0736 ER - TY - JOUR TI - Multiple stellar populations in 47 Tucanae DO - 10.1088/0004-637X/744/1/58 AU - Milone, A.P. AU - Piotto, G. AU - Bedin, L.R. AU - King, I.R. AU - Anderson, J. AU - Marino, A.F. AU - Bellini, A. AU - Gratton, R. AU - Renzini, A. AU - Stetson, P.B. AU - Cassisi, S. AU - Aparicio, A. AU - Bragaglia, A. AU - Carretta, E. AU - D'Antona, F. AU - Di Criscienzo, M. AU - Lucatello, S. AU - Monelli, M. AU - Pietrinferni, A. T2 - The Astrophysical Journal SN - 0004-637X VL - 744 IS - 1 SP - 58 AB - We use Hubble Space Telescope (HST) and ground-based imaging to study the multiple populations of 47 Tucanae (47 Tuc), combining high-precision photometry with calculations of synthetic spectra. Using filters covering a wide range of wavelengths, our HST photometry splits the main sequence into two branches, and we find that this duality is repeated in the subgiant and red giant regions, and on the horizontal branch. We calculate theoretical stellar atmospheres for main-sequence stars, assuming different chemical composition mixtures, and we compare their predicted colors through the HST filters with our observed colors. We find that we can match the complex of observed colors with a pair of populations, one with primeval abundance and another with enhanced nitrogen and a small helium enhancement, but with depleted C and O. We confirm that models of red giant and red horizontal branch stars with that pair of compositions also give colors that fit our observations. We suggest that the different strengths of molecular bands of OH, CN, CH, and NH, falling in different photometric bands, are responsible for the color splits of the two populations. Near the cluster center, in each portion of the color-magnitude diagram the population with primeval abundances makes up only ∼20% of the stars, a fraction that increases outward, approaching equality in the outskirts of the cluster, with a fraction ∼30% averaged over the whole cluster. Thus the second, He/N-enriched population is more concentrated and contributes the majority of the present-day stellar content of the cluster. We present evidence that the color-magnitude diagram of 47 Tuc consists of intertwined sequences of the two populations, whose separate identities can be followed continuously from the main sequence up to the red giant branch, and thence to the horizontal branch. A third population is visible only in the subgiant branch, where it includes ∼8% of the stars. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a59821b0-ba0a-4909-8c80-f3450e45f724 ER - TY - JOUR TI - Two methodologies for optical analysis of contaminated engine lubricants DO - 10.1088/0957-0233/23/1/015202 AU - Aghayan, H. AU - Bordatchev, E. AU - Yang, J. T2 - Measurement Science and Technology SN - 0957-0233 VL - 23 IS - 1 SP - 15202 KW - Automotive engine KW - Coherence function KW - Combustion engines KW - condition KW - Contaminant concentrations KW - Cross-correlation function KW - Distortion effects KW - Engine condition monitoring KW - Engine lubricants KW - Gray scale intensities KW - Indirect measurements KW - Measured parameters KW - Mechanical components KW - Monitoring and control KW - Nonuniformity KW - On-line measurement KW - Optical analysis KW - Optical image KW - Optical medium KW - Qualitative analysis KW - Relative intensity KW - Shape based KW - Statistical characteristics KW - Wear particles KW - Condition monitoring KW - Contamination KW - Coolants KW - Engines KW - Environmental impact KW - Geometrical optics KW - Impurities KW - Lubricants KW - Measurements KW - Mechanical properties KW - Monitoring KW - Optical correlation KW - Optical properties KW - Periodic structures KW - Sensors KW - Statistical methods KW - Quality control AB - The performance, efficiency and lifetime of modern combustion engines significantly depend on the quality of the engine lubricants. However, contaminants, such as gasoline, moisture, coolant and wear particles, reduce the life of engine mechanical components and lubricant quality. Therefore, direct and indirect measurements of engine lubricant properties, such as physical-mechanical, electro-magnetic, chemical and optical properties, are intensively utilized in engine condition monitoring systems and sensors developed within the last decade. Such sensors for the measurement of engine lubricant properties can be used to detect a functional limit of the in-use lubricant, increase drain interval and reduce the environmental impact. This paper proposes two new methodologies for the quantitative and qualitative analysis of the presence of contaminants in the engine lubricants. The methodologies are based on optical analysis of the distortion effect when an object image is obtained through a thin random optical medium (e.g. engine lubricant). The novelty of the proposed methodologies is in the introduction of an object with a known periodic shape behind a thin film of the contaminated lubricant. In this case, an acquired image represents a combined lubricant-object optical appearance, where an a priori known periodic structure of the object is distorted by a contaminated lubricant. In the object shape-based optical analysis, several parameters of an acquired optical image, such as the gray scale intensity of lubricant and object, shape width at object and lubricant levels, object relative intensity and width non-uniformity coefficient are newly proposed. Variations in the contaminant concentration and use of different contaminants lead to the changes of these parameters measured on-line. In the statistical optical analysis methodology, statistical auto- and cross-characteristics (e.g. auto- and cross-correlation functions, auto- and cross-spectrums, transfer function, coherence function, etc) are used for the analysis of combined object-lubricant images. Both proposed methodologies utilize the comparison of measured parameters and calculated object shape-based and statistical characteristics for fresh and contaminated lubricants. Developed methodologies are verified experimentally showing an ability to distinguish lubricant with 0%, 3%, 7% and 10% water and coolant contamination. This proves the potential applicability of the developed methodologies for on-line measurement, monitoring and control of the engine lubricant condition. © 2012 IOP Publishing Ltd. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2bfa8f1a-1014-4d26-8af5-7f0318b62b8f ER - TY - JOUR TI - Involvement of insulin-like growth factor 1 receptor signaling in the amyloid-β peptide oligomers-induced p75 neurotrophin receptor protein expression in mouse hippocampus DO - 10.3233/JAD-2012-120046 AU - Ito, S. AU - Ménard, M. AU - Atkinson, T. AU - Gaudet, C. AU - Brown, L. AU - Whitfield, J. AU - Chakravarthy, B. T2 - Journal of Alzheimer's Disease SN - 1387-2877 VL - 31 IS - 3 SP - 493 EP - 506 KW - amyloid beta protein[1-42] KW - neurotrophin receptor p75 KW - oligomer KW - somatomedin C receptor KW - Alzheimer disease KW - animal experiment KW - animal model KW - animal tissue KW - article KW - controlled study KW - disease model KW - female KW - hippocampus KW - human KW - human cell KW - in vivo study KW - male KW - microinjection KW - mouse KW - neuroblastoma cell KW - nonhuman KW - priority journal KW - protein expression KW - protein phosphorylation KW - transgenic mouse KW - wild type KW - Amyloid beta-Peptides KW - Animals KW - Cell Line, Tumor KW - Female KW - Gene Expression Regulation KW - Hippocampus KW - Humans KW - Male KW - Mice KW - Mice, Inbred C57BL KW - Mice, Transgenic KW - Peptide Fragments KW - Receptor, IGF Type 1 KW - Receptors, Nerve Growth Factor KW - Signal Transduction AB - The p75 neurotrophin receptor (p75NTR) has been thought to play a critical role in amyloid-β peptide (Aβ)-mediated neurodegeneration and Aβ metabolism in Alzheimer's disease (AD) brains. Our previous report showed that membrane-associated p75NTR protein expression was significantly increased in the hippocampi of two different strains of transgenic AD mice and was associated with the age-dependent elevation of Aβ1-42 levels. Here, we provide evidence that the Aβ1-42 oligomers known as ADDLs (Aβ-derived diffusible ligands) induce p75NTR protein expression through insulin-like growth factor 1 receptor (IGF-1R) phosphorylation in SH-SY5Y human neuroblastoma cells. An in vivo microinjection study demonstrated that microinjected ADDLs increased the p75NTR protein expression by 1.4-fold in the ipsilateral hippocampus compared to the contralateral hippocampus. In addition, ADDLs microinjected into mouse hippocampi facilitated IGF-1R phosphorylation within 30 min and the co-administration of picropodophyllin, an IGF-1R kinase inhibitor, blocked ADDLs-induced p75NTR expression. We examined the possible involvement of IGF-1R in the increased p75NTR protein expression in the hippocampi of 6-month-old AβPPswe/PS1dE9 AD model mice that had accumulated significant amounts of Aβ1-42 and showed significantly higher p75NTR expression than age-matched wild-type mice. We found that IGF-1R phosphorylation in these transgenic mice was higher than that in the wild-type mice. These findings indicate that Aβ1-42 oligomers stimulate the p75NTR protein expression in the hippocampus through IGF-1R signaling. Thus, Aβ1-42 oligomers-mediated IGF-1R activation may trigger an increase in p75NTR protein expression in the hippocampus of AD brain during the early stages of disease development. © 2012-IOS Press and the authors. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b39b0d6c-9fc8-4279-ae5d-e20c207c68c4 ER - TY - JOUR TI - Mesoporous nanostructured Nb-doped titanium dioxide microsphere catalyst supports for PEM fuel cell electrodes DO - 10.1021/am300002j AU - Chevallier, L. AU - Bauer, A. AU - Cavaliere, S. AU - Hui, R. AU - Rozière, J. AU - Jones, D.J. T2 - ACS Applied Materials and Interfaces SN - 1944-8244 VL - 4 IS - 3 SP - 1752 EP - 1759 KW - Doped titania KW - Electroactive KW - Electrocatalyst support KW - High specific surface area KW - High stability KW - Inorganic components KW - Ionic interaction KW - Mass activity KW - Mesoporous KW - Mesoporous shell KW - Microwave methods KW - Nano-structured KW - Oxygen reduction reaction KW - PEM fuel cell KW - Porosity gradients KW - Pt particle KW - Supported Pt KW - Templating method KW - TiO KW - Uniform dispersions KW - Voltammetric cycles KW - Cathodes KW - Cyclic voltammetry KW - Electrocatalysts KW - Electrolytic reduction KW - Mesoporous materials KW - Microspheres KW - Platinum KW - Proton exchange membrane fuel cells (PEMFC) KW - Titanium dioxide AB - Crystalline microspheres of Nb-doped TiO 2 with a high specific surface area were synthesized using a templating method exploiting ionic interactions between nascent inorganic components and an ionomer template. The microspheres exhibit a porosity gradient, with a meso-macroporous kernel, and a mesoporous shell. The material has been investigated as cathode electrocatalyst support for polymer electrolyte membrane (PEM) fuel cells. A uniform dispersion of Pt particles on the Nb-doped TiO 2 support was obtained using a microwave method, and the electrochemical properties assessed by cyclic voltammetry. Nb-TiO 2 supported Pt demonstrated very high stability, as after 1000 voltammetric cycles, 85% of the electroactive Pt area remained compared to 47% in the case of commercial Pt on carbon. For the oxygen reduction reaction (ORR), which takes place at the cathode, the highest stability was again obtained with the Nb-doped titania-based material even though the mass activity calculated at 0.9 V vs RHE was slightly lower. The microspherical structured and mesoporous Nb-doped TiO 2 is an alternative support to carbon for PEM fuel cells. © 2012 American Chemical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fdcb8e37-7c4f-4cd4-8545-8048bf9bb858 ER - TY - JOUR TI - Global gene deletion analysis exploring yeast filamentous growth DO - 10.1126/science.1224339 AU - Ryan, O. AU - Shapiro, R.S. AU - Kurat, C.F. AU - Mayhew, D. AU - Baryshnikova, A. AU - Chin, B. AU - Lin, Z.-Y. AU - Cox, M.J. AU - Vizeacoumar, F. AU - Cheung, D. AU - Bahr, S. AU - Tsui, K. AU - Tebbji, F. AU - Sellam, A. AU - Istel, F. AU - Schwarzmüller, T. AU - Reynolds, T.B. AU - Kuchler, K. AU - Gifford, D.K. AU - Whiteway, M. AU - Giaever, G. AU - Nislow, C. AU - Costanzo, M. AU - Gingras, A.-C. AU - Mitra, R.D. AU - Andrews, B. AU - Fink, G.R. AU - Cowen, L.E. AU - Boone, C. T2 - Science SN - 0036-8075 VL - 337 IS - 6100 SP - 1352 EP - 1356 KW - green fluorescent protein KW - transcription factor KW - transcription factor flo8 KW - transcription factor Mss11 KW - unclassified drug KW - gene expression KW - genome KW - growth KW - immune system KW - nutrient cycling KW - polyploidy KW - yeast KW - allele KW - article KW - biofilm KW - Candida albicans KW - cell structure KW - fungus growth KW - gene deletion KW - gene expression KW - gene identification KW - haploidy KW - nonhuman KW - phenotype KW - priority journal KW - promoter region KW - protein binding KW - protein localization KW - Saccharomyces cerevisiae KW - signal transduction KW - transcription regulation KW - Candida albicans KW - Saccharomyces cerevisiae KW - Saccharomycetales AB - The dimorphic switch from a single-cell budding yeast to a filamentous form enables Saccharomyces cerevisiae to forage for nutrients and the opportunistic pathogen Candida albicans to invade human tissues and evade the immune system. We constructed a genome-wide set of targeted deletion alleles and introduced them into a filamentous S. cerevisiae strain, S1278b. We identified genes involved in morphologically distinct forms of filamentation: haploid invasive growth, biofilm formation, and diploid pseudohyphal growth. Unique genes appear to underlie each program, but we also found core genes with general roles in filamentous growth, including MFG1 (YDL233w), whose product binds two morphogenetic transcription factors, Flo8 and Mss11, and functions as a critical transcriptional regulator of filamentous growth in both S. cerevisiae and C. albicans. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e3a0acfa-cd47-47c8-9ede-5f6745a4b8e7 ER - TY - JOUR TI - Hexane fraction of American ginseng suppresses colitis and colon cancer - Response DO - 10.1158/1940-6207.CAPR-12-0169 AU - Poudyal, D. AU - Le, P.M. AU - Davis, T. AU - Hofseth, A.B. AU - Chumanevich, A. AU - Chumanevich, A.A. AU - Wargovich, M.J. AU - Nagarkatti, M. AU - Nagarkatti, P.S. AU - Windust, A. AU - Hofseth, L.J. T2 - Cancer Prevention Research SN - 1940-6207 VL - 5 IS - 7 SP - 983 KW - ginseng extract KW - hexane KW - antiinflammatory activity KW - colitis KW - colon cancer KW - drug carcinogenicity KW - fractionation KW - ginseng KW - LD 50 KW - letter KW - nonhuman KW - priority journal DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 30ec2135-6b05-4393-af36-2dadf464d60f ER - TY - JOUR TI - Oocyte development and vitellogenin production in Northwest Atlantic Greenland halibut Reinhardtius hippoglossoides DO - 10.2960/J.v44.ms679 AU - Rideout, R.M. AU - Morgan, M.J. AU - Lambert, Y. AU - Cohen, A.M. AU - Banoub, J.H. AU - Treble, M. T2 - Journal of Northwest Atlantic Fishery Science SN - 1813-1859 VL - 44 SP - 15 EP - 29 KW - captivity KW - commercial species KW - developmental stage KW - fish KW - reproduction KW - reproductive behavior KW - spawning KW - Atlantic Ocean KW - Atlantic Ocean (Northwest) AB - Histological data presented here supports the notion of an uncommon oocyte development pattern for Greenland halibut, with two simultaneous groups of developing oocytes in the ovary, the larger group developing for the upcoming spawning season and the smaller group developing for next year (i.e. the duration of vitellogenesis is > 1 yr.). We analyzed blood samples collected from wild fish as well as fish that were part of the first documented study of Greenland halibut reproductive development in captivity in order to explore the annual cycle of vitellogenin production for this species. Despite the unusual oocyte development strategy there were no obvious differences in seasonal vitellogenin profiles versus fish with more traditional oocyte development strategies. Blood plasma vitellogenin levels generally peaked prior to or during spawning for those fish that successfully spawned, while patterns were highly variable for fish that did not spawn. Maximum plasma vitellogenin levels observed were 25 mg/ml and within the range of values observed for other fish species. Continued refinements in husbandry and experimental protocols for the study of Greenland halibut in captivity will provide a valuable tool for examining aspects of the species' biology that are difficult to ascertain based on sampling of only wild fish. © Her Magesty the Queen in right of Canada, 2012. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cafd8d93-4d20-4510-a416-cd8683a1474d ER - TY - JOUR TI - Aspects of in-situ consolidation of thermoplastic laminates manufactured by Automated Tape Placement AU - Brulotte, X.G. AU - Hubert, P. AU - Hojjati, M. T2 - International SAMPE Technical Conference T3 - 2012 SAMPE International Symposium and Exhibition - Emerging Opportunities: Materials and Process Solutions, 21 May 2012 through 24 May 2012, Baltimore, MD SN - 9781934551127 KW - Automated tape placement KW - Carbon/PEEK KW - Consolidation pressure KW - Deformation behaviour KW - Dynamic mechanical analyzer KW - In-situ KW - Manufacturing imperfections KW - Ply orientation KW - Processing condition KW - Processing parameters KW - Processing temperature KW - Steady state KW - Steady state deformation KW - Thermoplastic composite KW - Tow deformations KW - Transverse deformation KW - Compaction KW - Deformation KW - Exhibitions KW - Laminates KW - Manufacture KW - Optical microscopy KW - In situ processing AB - This paper focuses on the manufacturing of thermoplastic composite PEEK parts using Automated Tape Placement (ATP) with in-situ consolidation. The choice of the adequate processing parameters for the in-situ ATP is critical because no additional autoclave step is used to correct any manufacturing imperfections created during layup, or to homogenize the laminate consolidation. The current paper can be considered as a first step towards understanding the deformation behaviour of APC-2/IM7 (Cytec) in-situ ATP tape material subjected to various processing conditions. Compression analyses performed using a Dynamic Mechanical Analyzer (DMA) show that the material can quickly reach a steady state transverse deformation. The deformation behaviour of the pre-impregnated carbon/PEEK tape was investigated using a specially developed compaction apparatus. Processing parameters such as temperature, consolidation forces, and orientation of the deposited tow were independently controlled and the material's steady state deformation was measured by optical microscopy. The processing temperature was found to have negligible impact within the studied range. The consolidation pressure and ply orientation were found to contribute with similar magnitude to the tow deformation. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 52a23eef-1edf-429f-9ae8-81b0ee649bf4 ER - TY - CHAP TI - Environmental and dwell effects on the damage tolerance properties of ATI 718PLUS® alloy DO - 10.1002/9781118516430.ch82 AU - Kearsey, R. M. AU - Tsang, J. AU - Oppenheimer, S. AU - McDevitt, E. T2 - Superalloys 2012 T3 - 12th International Symposium on Superalloys, Superalloys 2012, September 9-13, 2012, Seven Springs, PA, USA SN - 9780470943205 SN - 9781118516430 SP - 741 EP - 749 KW - Dwell fatigue KW - Environmental damage KW - FCGR KW - Intergranular fracture KW - Waspaloy KW - Carbides KW - Cerium alloys KW - Crack tips KW - Cracks KW - Fatigue crack propagation KW - Fatigue of materials KW - Grain boundaries KW - Microstructural evolution KW - Oxidation KW - Stress corrosion cracking KW - Superalloys KW - Textures KW - Vacuum KW - Fracture AB - Fatigue crack growth rate (FCGR) and dwell-FCGR tests were conducted at 704C° in a vacuum environment and compared with data obtained under lab air conditions for various microstructural conditions of ATI 718Plus Alloy (718Plus) and Waspaloy. The results indicated that environmental damage has a significant impact on the FCGR characteristics of both alloys, particularly in the near-threshold regime. The dwell fatigue crack propagation behaviour under vacuum conditions displayed identical behaviour irrespective of differences in microstructural features. The observed crack growth rates under vacuum decreased dramatically compared to lab air test results, highlighting the crucial impact of environmental damage on the dwell-fatigue crack propagation resistance of both alloys. The fracture mode for 718Plus was observed to be predominately intergranular in both the FCGR and dwell-FCGR test conditions, with the effect of long-term thermal exposure leading to a larger fraction of transgranular failure. Waspaloy fracture surfaces revealed a predominantly transgranular deformation mode. The fracture surfaces of 718Plus and Waspaloy all exhibited transgranular fracture under vacuum test conditions and were nearly indistinguishable in crack topography. Dynamic embrittlement is believed to be the governing mechanism for intergranular failure of 718Plus leading to grain boundary decohesion. Improvement of dwell-fatigue crack propagation resistance of 718Plus may be strongly related to the coarsening of the γ hardening phase, with potential further improvement via implementation of a bimodal γ heat treatment. EDX analysis showed that the 8 phase just at the crack tip becomes oxidized and may be a contributing factor in the susceptibility of the grain boundaries during the dwell-FCGR tests. The presence of Nb-rich carbides along the dwell-fatigue crack path of 718Plus was also identified. Carbides located behind the crack front were heavily oxidized and those carbides observed just ahead of the crack tip showed no oxidation. It is believed that oxidation of these NbC particles near grain boundaries may be linked to the environmental susceptibility of 718Plus during dwell-fatigue crack propagation. © 2012 The Minerals, Metals, & Materials Society. All rights reserved. DA - 2012/10/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f309ef86-6acf-497a-8d9b-6c9b89d552fe ER - TY - JOUR TI - Characterization of 2,3-and 2,6-sialyltransferases from Helicobacter acinonychis DO - 10.1093/glycob/cws071 AU - Schur, M.J. AU - Lameignere, E. AU - Strynadka, N.C.J. AU - Wakarchuk, W.W. T2 - Glycobiology SN - 0959-6658 VL - 22 IS - 7 SP - 997 EP - 1006 KW - alpha 2,3 sialyltransferase KW - alpha 2,6 sialyltransferase KW - galactose KW - sialyltransferase KW - unclassified drug KW - aminosugar KW - bacterial protein KW - beta D galactoside alpha 2 6 sialyltransferase KW - beta galactoside alpha 2,3 sialyltransferase KW - beta-D-galactoside alpha 2-6-sialyltransferase KW - beta-galactoside alpha-2,3-sialyltransferase KW - hybrid protein KW - magnesium KW - manganese KW - n acetyllactosamine KW - N-acetyllactosamine KW - sialic acid derivative KW - sialyltransferase KW - article KW - bacterial genome KW - bacterium isolate KW - cheetah KW - controlled study KW - enzyme activation KW - enzyme analysis KW - enzyme substrate KW - Escherichia coli KW - gene expression KW - gene sequence KW - Helicobacter KW - Helicobacter acinonychis KW - molecular cloning KW - nonhuman KW - nucleotide sequence KW - priority journal KW - protein expression KW - sequence homology KW - tandem repeat KW - biosynthesis KW - chemical structure KW - chemistry KW - conformation KW - enzyme active site KW - enzyme specificity KW - enzymology KW - genetics KW - glycosylation KW - pH KW - structural homology KW - Escherichia coli KW - Helicobacter KW - Helicobacter acinonychis KW - Amino Sugars KW - Bacterial Proteins KW - Carbohydrate Conformation KW - Catalytic Domain KW - Cloning, Molecular KW - Glycosylation KW - Helicobacter KW - Hydrogen-Ion Concentration KW - Magnesium KW - Manganese KW - Models, Molecular KW - Recombinant Fusion Proteins KW - Sialic Acids KW - Sialyltransferases KW - Structural Homology, Protein KW - Substrate Specificity AB - Genome sequence data were used to clone and express two sialyltransferase enzymes of the GT-42 family from Helicobacter acinonychis ATCC 51104, a gastric disease isolate from Cheetahs. The deposited genome sequence for these genes contains a large number of tandem repeat sequences in each of them: HAC1267 (RQKELE)15 and HAC1268 (EEKLLEFKNI)13. We obtained two clones with different numbers of repeat sequences for the HAC1267 gene homolog and a single clone for the HAC1268 gene homolog. Both genes could be expressed in Escherichia coli and sialyltransferase activity was measured using synthetic acceptor substrates containing a variety of terminal sugars. Both enzymes were shown to have a preference for N-acetyllactosamine, and they each made a product with a different linkage to the terminal galactose. HAC1267 is a mono-functional 2,3-sialyltransferase, whereas HAC1268 is a mono-functional α2,6- sialyltransferase and is the first member of GT-42 to show α2,6- sialyltransferase activity. © 2012 The Author. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cc4e5c5d-dbaa-4045-88e7-abd3b5b11f35 ER - TY - JOUR TI - Structural characterization and mechanical evaluation of bioactive glass 45S5 foams obtained by a powder technology approach DO - 10.1111/j.1551-2916.2012.05465.x AU - Aguilar-Reyes, E.A. AU - León-Patiño, C.A. AU - Jacinto-Diaz, B. AU - Lefebvre, L.-P. T2 - Journal of the American Ceramic Society SN - 0002-7820 VL - 95 IS - 12 SP - 3776 EP - 3780 KW - Bone ingrowth KW - Different structure KW - Foam structure KW - Glass particles KW - Mechanical evaluation KW - Mechanical points KW - Micro-structural KW - National Research Council KW - Open porosity KW - Polymer foams KW - Porous bodies KW - Powder Technology KW - Sintering temperatures KW - Solid structures KW - Structural characterization KW - Binders KW - Bioactive glass KW - Industrial research KW - Sintering KW - Sodium KW - Strength of materials AB - Bioactive glass 45S5 foams were produced using a powder technology process developed by The National Research Council Canada-Industrial Materials Institute. NRC-IMI's proprietary process, combining powder technology and polymer foam technique, allows the production of materials having different structures and properties. It can be used to produce components into various forms, such as fully porous bodies or coatings on solid structures. During foaming, the foaming agent is decomposed and expands the binder-bioactive glass suspension. Then, the binder is burnt out by heating the sample at 500°C and finally the bioactive glass particle network is sintered to consolidate the material. Foams sintered at various temperatures were characterized from a microstructural and mechanical point of view. The foam structure and properties are affected by the sintering temperature when it is varied between 950°C and 1025°C. Foams exhibited open porosity (64%-79%) and pore size (335-530 μm) optimal for bone ingrowth. In all cases, the glass crystallized during sintering and the material was mostly composed of Na6Ca 3Si6O18 and Na2Ca 4(PO4)2SiO4 phases. The mechanical strength increased from 1.7 to 5.5 MPa while the density of the material increased from 0.56 to 0.97 g/cm3. © 2012 The American Ceramic Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 909be4fe-9da5-4204-bc66-aa3c77051934 ER - TY - JOUR TI - ZZ Cyg: fundamental parameters AU - Nelson, Robert H. T2 - Information Bulletin on Variable Stars SN - 0374-0676 IS - 6016 DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d4f3a494-8dbf-453f-bb4b-9891fdbefe8e ER - TY - JOUR TI - Evidence that the bursting component of the X-ray radiation from 3C 111 originates in the PC-scale jet DO - 10.1007/s10509-011-0962-9 AU - Bell, M.B. AU - Comeau, S.P. T2 - Astrophysics and Space Science SN - 0004-640X VL - 339 IS - 1 SP - 143 EP - 149 AB - Evidence is presented indicating that the bursting component of the X-ray radiation detected in the nuclear region of the active radio galaxy 3C 111 comes from the blobs ejected in the pc-scale jet and not from the accretion disc. After each new outburst the radio flux density associated with it increases to a peak in ~1 year and then subsides over a period of 1-2 years with the flux falling off exponentially as the blob moves outward and dissipates. Similar peaks (bursts) are seen in the X-ray light curve and a cross-correlation between the two shows a very high correlation with the X-ray peaks leading the radio peaks by ~100 days. A second cross-correlation, this time between the radio event start times and the X-ray light curve, also shows a significant correlation. When this is taken together with the long (~1 yr) delay between the start of each ejection event and its associated X-ray peak it indicates that this bursting component of the X-ray flux must be associated with the ejected blobs in the pc-scale jet and not with the accretion disc. Because X-ray telescopes do not have the resolution required to resolve the accretion disc area from the pc-scale jet, this paper is the first to present observational evidence that can pinpoint the point of origin of at least those long-timescale X-ray bursts with durations of 1-3 yrs. © 2011 Springer Science+Business Media B.V. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : aa62f194-a5ef-46fa-a339-828a84c0d176 ER - TY - JOUR TI - Metal frame reinforced ceramic matrix composite for high temperature applications DO - 10.1115/GT2012-68293 AU - Kibsey, M. AU - Mohammadi, T. AU - Huang, X. AU - Kearsey, R. T2 - Proceedings of the ASME Turbo Expo T3 - ASME Turbo Expo 2012: Turbine Technical Conference and Exposition, GT 2012, 11 June 2012 through 15 June 2012, Copenhagen SN - 9780791844717 VL - 5 SP - 81 EP - 89 KW - Cyclic oxidation tests KW - Future improvements KW - Mechanical properties at high temperatures KW - NiCrAlY bond coats KW - Oxidation resistant coating KW - Plasma spray techniques KW - Preliminary assessment KW - The scanning electron microscopes (SEM) KW - Ceramic matrix composites KW - Chemical bonds KW - Cracks KW - Exhibitions KW - Fabrication KW - Fracture KW - Gas turbines KW - High temperature applications KW - Impact testing KW - Isotherms KW - Jigs KW - Load testing KW - Mechanical properties KW - Molybdenum KW - Plasma spraying KW - Reinforcement KW - Scanning electron microscopy KW - Yttria stabilized zirconia KW - Zirconia KW - Wire AB - The design, fabrication and preliminary assessment of novel metal reinforced ceramic matrix composite (CMC) materials are reported in this study. The design is based on the assumption that the metallic reinforcing structure can increase the work of fracture through the action of wire pullout, crack deflection and plastic deformation. In particular, the current CMC is composed of a molybdenum wire structure within a 7.5 wt% yttria-stabilized zirconia (7YSZ) ceramic matrix (Mo/YSZ). A unique jig is designed to assist the fabrication of the Mo mesh. Subsequently a NiCrAlY bond coat and finally a 7YSZ matrix are applied to the Mo mesh structure using a plasma spray technique. The as-fabricated and heat treated Mo/YSZ are subjected to impact and 3-point bend tests. The impact testing results show that heat treatment after spraying increases the impact energy possibly due to the improved bonding between Mo, NiCrAlY and 7YSZ. During 3-point bend testing, the incorporation of Mo mesh in 7YSZ increases the load at yield point, the peak load and the displacement to failure. After isothermal and cyclic oxidation tests at 1050°C for 330 hours, the Mo/YSZ CMC is examined under optical and scanning electron microscopes (SEM). The results show that the NiCrAlY bond coat delaminates from the Mo wire and also forms radial cracks during the spraying process. It is for this reason that the Mo wire suffers from rapid oxidization during isothermal and cyclic oxidation tests, causing separation of the reinforcement from the 7YSZ matrix. Future improvement to the current process will be to select and deposit a more effective oxidation resistant coating on the Mo wire in order to allow the metal frame-reinforced CMC concept to achieve the desired chemical and mechanical properties at high temperatures. Copyright © 2012 by ASME. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 260d4e8f-ef31-4d47-af74-2f4d18048b51 ER - TY - JOUR TI - Characterization of the PEM fuel cell catalyst layer microstructure by nonlinear least-squares parameter estimation DO - 10.1149/2.041205jes AU - Dobson, P. AU - Lei, C. AU - Navessin, T. AU - Secanell, M. T2 - Journal of the Electrochemical Society SN - 0013-4651 VL - 159 IS - 5 SP - B514 EP - B523 KW - Agglomerate sizes KW - Catalyst layers KW - Experimental visualization KW - Membrane electrode assemblies KW - Microstructural parameters KW - Model parameters KW - Model prediction KW - Multi-physics KW - Nonlinear least squares KW - Operating condition KW - Parameter estimation algorithm KW - PEM fuel cell KW - Structural parameter KW - Catalysts KW - Mathematical models KW - Parameter estimation KW - Uncertainty analysis KW - Proton exchange membrane fuel cells (PEMFC) AB - Models of polymer electrolyte membrane fuel cells (PEMFC) have become increasingly complex, using many parameters to define the behavior of species and the performance of the cell. A framework is presented here to couple an agglomerate electrode based, multi-dimensional, multi-physics mathematical model of membrane electrode assembly (MEA) model with an optimization-based nonlinear least-squares parameter estimation algorithm. The framework is used to estimate the micro-structural parameters of the catalyst layer such as agglomerate size. The results show that a set of data over a range of operating conditions can be accurately described by using a unique set of structural parameters that match experimental visualization of the catalyst layer. Extension of this methodology can be used to systematically estimate any model parameters in order to reduce uncertainty in model predictions. © 2012 The Electrochemical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b60dd874-a145-4882-aca9-3cd37547ab87 ER - TY - JOUR TI - Linear friction welding of a forged near-α titanium alloy DO - 10.4028/www.scientific.net/MSF.706-709.211 AU - Dalgaard, E. AU - Wanjara, P. AU - Gholipour, J. AU - Jonas, J.J. T2 - Materials Science Forum T3 - 7th International Conference on Processing and Manufacturing of Advanced Materials, THERMEC'2011, 1 August 2011 through 5 August 2011, Quebec City, QC SN - 0255-5476 SN - 9783037853030 VL - 706-709 SP - 211 EP - 216 KW - Aerospace KW - Axial pressures KW - Base material KW - Compressor disks KW - Electron back scatter diffraction KW - Fatigue strength KW - IMI834 KW - Linear friction welding KW - Phase fractions KW - Thermomechanically affected zones KW - Weld zone KW - Weldments KW - Aerospace industry KW - Friction welding KW - Textures KW - Tin KW - Titanium alloys KW - Welding KW - Zirconium KW - Alloys KW - Cerium alloys KW - Creep KW - Creep resistance KW - Friction KW - Molybdenum KW - Niobium KW - Titanium KW - Tribology KW - Creep resistance KW - Titanium alloys AB - IMI834 (Ti-5.8Al-4Sn-3.5Zr-0.7Nb-0.5Mo-0.35Si) is a high-tech near-α titanium alloy with improved creep resistance and mechanical property retention at temperatures up to 600°C [1]. It is used in the aerospace industry for compressor disks and blades due to its excellent balance between creep resistance and fatigue strength [2]. The linear friction welding (LFW) behaviour of IMI834 displaying an initial bimodal α+β microstructure was investigated using varying axial pressures during welding. Electron backscatter diffraction (EBSD) was used to characterize the texture and phase fraction of the welded IMI834 samples in the weld zone (WZ) and thermomechanically affected zones (TMAZ) in relation to the base material. Based on microhardness evaluation of the weldments, the WZ was determined to be slightly harder than the base material. © 2012 Trans Tech Publications, Switzerland. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 712c43d9-4b42-494d-b2b8-43e1fd61aef9 ER - TY - JOUR TI - Partial oligomerization of pyolysin induced by a disulfide-tethered mutant DO - 10.1139/o2012-029 AU - Pokrajac, L. AU - Baik, C. AU - Harris, J.R. AU - Sarraf, N.S. AU - Palmer, M. T2 - Biochemistry and Cell Biology SN - 0829-8211 VL - 90 IS - 6 SP - 709 EP - 717 KW - Bacterial toxin KW - Cholesterol-dependent cytolysins KW - Disulfide bonds KW - Equimolar mixtures KW - Hybrid oligomers KW - Membrane insertion KW - Pore formation KW - Protein activity KW - Pyolysin KW - Trans-membrane pores KW - Wild types KW - Cholesterol KW - Covalent bonds KW - Lipid bilayers KW - Membranes KW - Oligomerization KW - Pore size KW - Proteins KW - Sulfur compounds KW - Oligomers KW - bacterial toxin KW - disulfide KW - pyolysin KW - unclassified drug KW - Arcanobacterium pyogenes KW - article KW - bacterial mutation KW - bacterium mutant KW - channel gating KW - complex formation KW - controlled study KW - Escherichia coli KW - gene insertion KW - hemolysis KW - oligomerization KW - Bacterial Proteins KW - Bacterial Toxins KW - Binding Sites KW - Cell Membrane KW - Cytotoxins KW - Disulfides KW - Hemolysin Proteins KW - Mutation KW - Polymerization KW - Protein Conformation KW - Protein Subunits KW - Bacteria (microorganisms) AB - The bacterial toxin pyolysin (PLO) belongs to the family of cholesterol-dependent cytolysins (CDCs), which form large, ring-shaped oligomeric pores in cholesterol-containing membranes. Monomeric CDC molecules have a structure of four domains, with domains 2 and 3 packed against each other. After binding to target membranes containing cholesterol, toxin monomers oligomerize into pre-pore complexes. Trans-membrane pores form when the pre-pores insert into the lipid bilayer. Membrane insertion requires each subunit in the pre-pore to undergo a significant change in conformation, including the separation of domains 2 and 3. We here characterize a pyolysin mutant with an engineered disulfide bond between domains 2 and 3. The disulfide-tethered mutant binds to membranes but does not form oligomers. When mixed with wild type PLO, the two proteins form hybrid oligomers, which are reduced in size and arc-shaped rather than ring-shaped. With equimolar mixtures or the disulfide mutant in slight excess, the hybrid oligomers retain pore-forming activity, while a larger excess of the mutant suppresses pore formation. These results support a "partially cooperative" mode of protein activity, in which a limited number of functional subunits within an oligomer have to cooperate to initiate membrane insertion and pore formation. © 2012 Published by NRC Research Press. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 823501d5-556d-4029-bce5-fad85173dea8 ER - TY - JOUR TI - Probabilistic models for focused web crawling DO - 10.1111/j.1467-8640.2012.00411.x AU - Liu, H. AU - Milios, E. T2 - Computational Intelligence SN - 0824-7935 VL - 28 IS - 3 SP - 289 EP - 328 KW - Best first search KW - Conditional random field KW - Domain specific KW - Experimental validations KW - Focused crawler KW - Focused crawling KW - Focused web crawling KW - Global optimal solutions KW - GraphicaL model KW - Hidden state KW - Hop distance KW - Link analysis KW - Local classifier KW - Maximum entropy Markov model KW - Overlapping features KW - Personalized search KW - Probabilistic models KW - Sequential patterns KW - Text content KW - Topical crawlers KW - Web Mining KW - Web searches KW - Hidden Markov models KW - Learning systems KW - Websites KW - Learning algorithms AB - A focused crawler is an efficient tool used to traverse the Web to gather documents on a specific topic. It can be used to build domain-specific Web search portals and online personalized search tools. Focused crawlers can only use information obtained from previously crawled pages to estimate the relevance of a newly seen URL. Therefore, good performance depends on powerful modeling of context as well as the quality of the current observations. To address this challenge, we propose capturing sequential patterns along paths leading to targets based on probabilistic models. We model the process of crawling by a walk along an underlying chain of hidden states, defined by hop distance from target pages, from which the actual topics of the documents are observed. When a new document is seen, prediction amounts to estimating the distance of this document from a target. Within this framework, we propose two probabilistic models for focused crawling, Maximum Entropy Markov Model (MEMM) and Linear-chain Conditional Random Field (CRF). With MEMM, we exploit multiple overlapping features, such as anchor text, to represent useful context and form a chain of local classifier models. With CRF, a form of undirected graphical models, we focus on obtaining global optimal solutions along the sequences by taking advantage not only of text content, but also of linkage relations. We conclude with an experimental validation and comparison with focused crawling based on Best-First Search (BFS), Hidden Markov Model (HMM), and Context-graph Search (CGS). © 2012 Wiley Periodicals, Inc. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 29ad1645-e1b5-4487-8572-ed43fc07353c ER - TY - JOUR TI - A search for ob associations near southern long-period cepheids. V. AQ puppis and V620 puppis DO - 10.1088/0004-6256/144/6/187 AU - Turner, D.G. AU - Van Den Bergh, S. AU - Younger, P.F. AU - Majaess, D.J. AU - Pedreros, M.H. AU - Berdnikov, L.N. T2 - Astronomical Journal SN - 0004-6256 VL - 144 IS - 6 SP - 187 AB - A photometric UBV survey is presented for 610 stars in a region surrounding the Cepheid AQ Puppis and centered southwest of the variable, based upon photoelectric measures for 14 stars and calibrated iris photometry of photographic plates of the field for 596 stars. An analysis of reddening and distance for program stars indicates that the major dust complex in this direction is ∼1.8 kpc distant, producing differential extinction described by a ratio of total-to-selective extinction of R = A V /E B-V = 3.10 ± 0.20. Zero-age main-sequence fitting for the main group of B-type stars along the line of sight yields a distance of 3.21 ± 0.19 kpc (V 0 - M V = 12.53 ± 0.13 s.e.). The 2997 Cepheid AQ Pup, of field reddening E B-V = 0.47 ± 0.07 (E B-V (B0) = 0.51 ± 0.07), appears to be associated with B-type stars lying within 5′ of it as well as with a sparse group of stars, designated Turner 14, centered south of it at J2000.0 = 07:58:37, -29:25:00, with a mean reddening of E B-V = 0.81 ± 0.01. AQ Pup has an inferred luminosity as a cluster member of 〈M V 〉 = -5.40 ± 0.25 and an evolutionary age of 3 × 10 7 yr. Its observed rate of period increase of +300.1 ± 1.2 s yr -1 is an order of magnitude larger than what is observed for Cepheids of comparable period in the third crossing of the instability strip, and may be indicative of a high rate of mass loss or a putative fifth crossing. Another sparse cluster, designated Turner 13, surrounds the newly recognized 259 Cepheid V620 Pup, of space reddening E B-V = 0.64 ± 0.02 (E B-V (B0) = 0.68 ± 0.02), distance 2.88 ± 0.11 kpc (V 0-M V = 12.30 ± 0.08 s.e.), evolutionary age 10 8 yr, and an inferred luminosity as a likely cluster member of 〈M V 〉 = -2.74 ± 0.11. V620 Pup is tentatively identified as a first crosser, pending additional observations. © 2012. The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a61875e1-a2f8-4426-a711-046e4f48a75f ER - TY - JOUR TI - Electronic properties of Si(111)-7×7 and related reconstructions: Density functional theory calculations DO - 10.1103/PhysRevB.85.195315 AU - Smeu, M. AU - Guo, H. AU - Ji, W. AU - Wolkow, R.A. T2 - Physical Review B - Condensed Matter and Materials Physics SN - 1098-0121 VL - 85 IS - 19 SP - 195315 AB - The 7×7 reconstruction of Si(111) has the interesting property of being metallic despite bulk Si being a semiconductor. This surface has a complex reconstruction that takes on a dimer-adatom stacking fault (DAS) structure composed of adatoms, rest atoms, and several other key features. It is believed that the dangling bonds of the adatoms play a crucial role in the high conductivity and that this is predominantly a surface-state band effect. To elucidate the details of this mechanism, we investigate a set of related Si(111) reconstructions of increasing complexity in order to resolve the effect of the different DAS features on the electronic and transport properties of the Si(111)-7×7 surface. Density functional theory calculations are carried out on the √3×√3-R30 -, 2×2, 5×5, and 7×7 reconstructions of Si(111). Since these surfaces are modeled as two-dimensional slabs, a careful investigation is carried out to determine the slab thickness needed to capture the structural and electronic properties of these systems. The densities of states (DOSs) projected on different atoms in these surfaces are then compared, revealing that the √3×√3, 5×5, and 7×7 surfaces are metallic, while the 2×2 surface is semiconducting. Finally, the DOSs for Si(111)-7×7 are related to scanning tunneling microscope data to offer an explanation for different adatom prominence trends depending on Si sample doping. © 2012 American Physical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ea758e3f-822c-4d65-91f8-7bd9b5cd360f ER - TY - JOUR TI - Multiband sensor using thick holographic gratings for sulfur detection by laser-induced breakdown spectroscopy DO - 10.1364/AO.51.0000B7 AU - Gagnon, D. AU - Lessard, S. AU - Verhaegen, M. AU - Mutchmore, P. AU - Bouchard, P. AU - Doucet, F.R. AU - Sabsabi, M. T2 - Applied Optics SN - 0003-6935 VL - 51 IS - 7 SP - B7 EP - B12 KW - Efficient systems KW - High-end systems KW - Limit of detection KW - Multi-band sensors KW - Near-IR KW - Novel concept KW - Output signal KW - Oxygen molecule KW - Signal integration KW - Spectral filtering KW - Sulfur detection KW - Temporal synchronization KW - Vacuum UV KW - Atomic emission spectroscopy KW - Holographic gratings KW - Sulfur KW - Signal detection AB - Detection of sulfur by optical emission spectroscopy generally presents some difficulties because the strongest lines are in the vacuum UV below 185 nm and therefore are readily absorbed by oxygen molecules in air. A novel concept for a low-cost and efficient system to detect sulfur using near-IR bands by laser-induced breakdown spectroscopy is here proposed. This concept is based on customized thick holographic gratings as spectral filtering elements. The signal integration and the temporal synchronization are performed using built-in custom electronics that amplify and integrate or trigger photodiode output signals. In this work, we use the near-IR lines at 921.287 nm and a background reference at 900 nm. Preliminary results show a limit of detection comparable to that of a conventional high-end system. © 2012 Optical Society of America. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1545fd7b-1e2a-48e5-b85b-ba6a59777e6f ER - TY - JOUR TI - Synthetic archaeosome vaccines containing triglycosylarchaeols can provide additive and long-lasting immune responses that are enhanced by archaetidylserine DO - 10.1155/2012/513231 AU - Sprott, G.D. AU - Yeung, A. AU - Dicaire, C.J. AU - Yu, S.H. AU - Whitfield, D.M. T2 - Archaea SN - 1472-3646 VL - 2012 SP - 513231 KW - Archaea KW - Halobacterium salinarum KW - Mus KW - antibody KW - archaeol lipid KW - cancer vaccine KW - glycerol ether KW - glycolipid KW - immunological adjuvant KW - tumor antigen KW - animal KW - article KW - blood KW - C57BL mouse KW - CD4+ T lymphocyte KW - CD8+ T lymphocyte KW - chemistry KW - Halobacterium salinarum KW - immunology KW - isolation and purification KW - mouse KW - neoplasm KW - pathology KW - Adjuvants, Immunologic KW - Animals KW - Antibodies KW - Antigens, Neoplasm KW - Cancer Vaccines KW - CD4-Positive T-Lymphocytes KW - CD8-Positive T-Lymphocytes KW - Glyceryl Ethers KW - Glycolipids KW - Halobacterium salinarum KW - Mice KW - Mice, Inbred C57BL KW - Neoplasms AB - The relation between archaeal lipid structures and their activity as adjuvants may be defined and explored by synthesizing novel head groups covalently linked to archaeol (2,3-diphytanyl-sn-glycerol). Saturated archaeol, that is suitably stable as a precursor for chemical synthesis, was obtained in high yield from Halobacterium salinarum. Archaeosomes consisting of the various combinations of synthesized lipids, with antigen entrapped, were used to immunize mice and subsequently determine CD8+ and CD4+-T cell immune responses. Addition of 45 mol of the glycolipids gentiotriosylarchaeol, mannotriosylarchaeol or maltotriosylarchaeol to an archaetidylglycerophosphate-O-methyl archaeosome, significantly enhanced the CD8+ T cell response to antigen, but diminished the antibody titres in peripheral blood. Archaeosomes consisting of all three triglycosyl archaeols combined with archaetidylglycerophosphate-O-methyl (15/15/15/55 mol) resulted in approximately additive CD8+ T cell responses and also an antibody response not significantly different from the archaetidylglycerophosphate-O- methyl alone. Synthetic archaetidylserine played a role to further enhance the CD8+ T cell response where the optimum content was 2030 mol. Vaccines giving best protection against solid tumor growth corresponded to the archaeosome adjuvant composition that gave highest immune activity in immunized mice. © 2012 G. Dennis Sprott et al. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e74241ce-40c2-42f1-827f-d61287ebc165 ER - TY - JOUR TI - Effect of single-walled carbon nanotubes on processing and property enhancement of epoxy adhesives and laminates AU - Ashrafi, B. AU - Johnston, A. AU - Jakubinek, M.B. AU - Martinez-Rubi, Y. AU - Simard, B. AU - Hubert, P. T2 - International SAMPE Technical Conference T3 - 2012 SAMPE International Symposium and Exhibition - Emerging Opportunities: Materials and Process Solutions, 21 May 2012 through 24 May 2012, Baltimore, MD SN - 9781934551127 KW - End-uses KW - Epoxy adhesives KW - High temperature KW - Laminate composites KW - Mechanical and electrical properties KW - Property improvement KW - Aluminum KW - Electric properties KW - Exhibitions KW - Glass fibers KW - Laminated composites KW - Mechanical properties KW - Resins KW - Single-walled carbon nanotubes (SWCN) KW - Epoxy resins AB - In this work, the effects of single walled carbon nanotubes (SWCNTs) on mechanical and electrical properties of two epoxy resins (a high temperature aerospace-grade epoxy and an aerospace-grade adhesive) were evaluated. The performance of these two SWCNT-modified epoxy resins was also studied in their end-use applications, as a matrix for a glass fiber laminate composites and as an adhesive for aluminum-to-aluminum bonding, respectively. The results suggest that the mechanical and electrical property improvements observed in bulk resin due the addition of SWCNTs do not necessarily translate into comparable property enhancements in laminates and joints. It was found that the electrical property improvements of nano-modified laminates exceeded those of bulk SWCNT-modified epoxy. The translation of mechanical properties from bulk resin to the structural level, on the other hand, was found to be less successful. The results are discussed in terms of challenges associated with processing and resin-fiber interaction. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d8c1a7c0-079c-4517-a159-8cb140712305 ER - TY - JOUR TI - Structure and stability of an amorphous water-methane mixture produced by cold compression of methane hydrate DO - 10.1103/PhysRevB.86.054110 AU - Tulk, C.A. AU - Klug, D.D. AU - Molaison, J.J. AU - Dos Santos, A.M. AU - Pradhan, N. T2 - Physical Review B - Condensed Matter and Materials Physics SN - 1098-0121 VL - 86 IS - 5 SP - 54110 AB - In a process similar to the formation of high-density amorphous ice, amorphous methane hydrate was formed by the pressure-induced collapse of crystalline methane clathrate at 32 kbar and 100 K. This produced a regular array of methane embedded within cavities in an amorphous water network. In situ annealing results in further densification into a more disordered and higher density amorphous state before crystallization into ice VIII and hexagonal clathrate. Whereas the very high-density amorphous form of pure water undergoes a glass transition near 130 K at low pressure and crystallizes over a broad pressure range at ∼160 K, the amorphous network of the water-methane binary system exhibits a region of metastability that persists up to 220 K between 15 and 40kbar. It appears that in this system the connectivity of the water network exhibits sufficiently low mobility so as to inhibit the diffusion and phase separation of the constituents until 220 K, where the high-pressure ice VIII crystallization can occur. The structure of the amorphous form is studied by neutron diffraction and the hydration of methane in this disordered water network is more closely related to the small clathrate cage than the large. ©2012 American Physical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 34bbba1f-1f61-4c2d-9432-4909084e2f5a ER - TY - JOUR TI - Robot task planning and trajectory learning for flexible automation DO - 10.1115/DETC2012-71359 AU - Mantegh, I. T2 - Proceedings of the ASME Design Engineering Technical Conference T3 - ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, IDETC/CIE 2012, 12 August 2012 through 12 August 2012, Chicago, IL SN - 9780791845035 VL - 4 IS - PARTS A AND B SP - 1347 EP - 1353 KW - Flexible automation KW - Human demonstrations KW - Key Patterns KW - Native language KW - Programming by demonstration KW - Robot trajectory KW - Task planning KW - Trajectory pattern KW - Algorithms KW - Design KW - Robots KW - Trajectories KW - Robot programming AB - A task planning method is presented to model and reproduce robot trajectories based on those captured from human demonstrations. In the framework of the Programming by Demonstration (PbD) approach, task planning algorithm is developed to determine the general type of trajectory pattern, its parameters, and its kinematic profile. The pattern is described independently of the shape of the surface on which it is demonstrated. Key pattern points are identified based on changes in direction and velocity, and are then reduced based on their proximity. The results of the analysis are provided are used inside a task planning algorithm, to produce robot trajectories based on the workpiece geometries. The trajectory is output in the form of robot native language code so that it can be readily downloaded on the robot. © 2012 by ASME. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1e2faa12-927f-446c-a81e-d057bb512088 ER - TY - JOUR TI - Quantum interference between three two-spin states in a double quantum dot DO - 10.1103/PhysRevLett.108.226802 AU - Studenikin, S.A. AU - Aers, G.C. AU - Granger, G. AU - Gaudreau, L. AU - Kam, A. AU - Zawadzki, P. AU - Wasilewski, Z.R. AU - Sachrajda, A.S. T2 - Physical Review Letters SN - 0031-9007 VL - 108 IS - 22 SP - 226802 KW - Coherence time KW - Density matrix KW - Double quantum dots KW - Interference patterns KW - Quantum interference KW - Singlet state KW - Theoretical prediction KW - Two-qubit KW - Experiments KW - Quantum computers KW - Quantum interference devices KW - Semiconductor quantum dots KW - Current voltage characteristics AB - Qubits based on the singlet (S) and the triplet (T 0, T +) states in double quantum dots have been demonstrated in separate experiments. It has been recently proposed theoretically that under certain conditions a quantum interference could occur from the interplay between these two qubit species. Here we report experiments and modeling that confirm these theoretical predictions and identify the conditions under which this interference occurs. Density matrix calculations show that the interference pattern manifests primarily via the occupation of the common singlet state. The S/T 0 qubit is found to have a much longer coherence time as compared to the S/T + qubit. © 2012 American Physical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 818ad410-f9af-483a-93fa-8feaf267f262 ER - TY - JOUR TI - Silicon nanowire based optical XOR logic gate at 40Gb/s for DPSK data AU - Li, F. AU - Vo, T.D. AU - Husko, C. AU - Pelusi, M. AU - Xu, D.-X. AU - Ma, R. AU - Janz, S. AU - Eggleton, B.J. AU - Moss, D.J. T2 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012 T3 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012, 6 May 2012 through 11 May 2012, San Jose, CA SN - 9781467318396 SP - 6325658 KW - DPSK signals KW - Error free operations KW - Logic functions KW - Optical XOR KW - Silicon nanowires KW - System penalty KW - Lasers KW - Nanowires KW - Silicon KW - Four wave mixing AB - We demonstrate all-optical XOR logic function for 40Gb/s DPSK signals in the C-band, based on four-wave mixing (FWM) in a silicon nanowire. Error-free operation with a system penalty of ∼ 4.3dB at 10-9 BER has been achieved. © 2012 OSA. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9ee40d42-4b8b-49b4-afee-5b1323208697 ER - TY - JOUR TI - Transcriptional and metabolomic analysis of Ascophyllum nodosum mediated freezing tolerance in Arabidopsis thaliana DO - 10.1186/1471-2164-13-643 AU - Nair, P. AU - Kandasamy, S. AU - Zhang, J. AU - Ji, X. AU - Kirby, C. AU - Benkel, B. AU - Hodges, M.D. AU - Critchley, A.T. AU - Hiltz, D. AU - Prithiviraj, B. T2 - BMC Genomics SN - 1471-2164 VL - 13 IS - 1 SP - 643 KW - carboxylic acid KW - fatty acid KW - proline KW - proline dehydrogenase KW - pyrroline 5 carboxylate reductase KW - sugar KW - sugar alcohol KW - Arabidopsis KW - article KW - Ascophyllum KW - ascophyllum nodosum KW - controlled study KW - cytosol KW - down regulation KW - freezing KW - freezing tolerance KW - gene expression KW - genetic transcription KW - heteronuclear multiple bond correlation KW - heteronuclear single quantum coherence KW - lipid composition KW - lipophilicity KW - metabolomics KW - nonhuman KW - nuclear magnetic resonance spectroscopy KW - osmotic stress KW - P5CS1 gene KW - P5CS2 gene KW - plant gene KW - ProDH gene KW - proton nuclear magnetic resonance KW - sfr4 gene KW - transcriptomics KW - upregulation KW - Arabidopsis KW - Ascophyllum KW - Carbohydrate Metabolism KW - Freezing KW - Gene Expression Profiling KW - Hot Temperature KW - Hydrophobic and Hydrophilic Interactions KW - Metabolomics KW - Mutation KW - Proline KW - Solubility KW - Transcription, Genetic KW - Arabidopsis KW - Arabidopsis thaliana KW - Ascophyllum nodosum AB - Background: We have previously shown that lipophilic components (LPC) of the brown seaweed Ascophyllum nodosum (ANE) improved freezing tolerance in Arabidopsis thaliana. However, the mechanism(s) of this induced freezing stress tolerance is largely unknown. Here, we investigated LPC induced changes in the transcriptome and metabolome of A. thaliana undergoing freezing stress.Results: Gene expression studies revealed that the accumulation of proline was mediated by an increase in the expression of the proline synthesis genes P5CS1 and P5CS2 and a marginal reduction in the expression of the proline dehydrogenase (ProDH) gene. Moreover, LPC application significantly increased the concentration of total soluble sugars in the cytosol in response to freezing stress. Arabidopsis sfr4 mutant plants, defective in the accumulation of free sugars, treated with LPC, exhibited freezing sensitivity similar to that of untreated controls. The 1H NMR metabolite profile of LPC-treated Arabidopsis plants exposed to freezing stress revealed a spectrum dominated by chemical shifts (δ) representing soluble sugars, sugar alcohols, organic acids and lipophilic components like fatty acids, as compared to control plants. Additionally, 2D NMR spectra suggested an increase in the degree of unsaturation of fatty acids in LPC treated plants under freezing stress. These results were supported by global transcriptome analysis. Transcriptome analysis revealed that LPC treatment altered the expression of 1113 genes (5%) in comparison with untreated plants. A total of 463 genes (2%) were up regulated while 650 genes (3%) were down regulated.Conclusion: Taken together, the results of the experiments presented in this paper provide evidence to support LPC mediated freezing tolerance enhancement through a combination of the priming of plants for the increased accumulation of osmoprotectants and alteration of cellular fatty acid composition. © 2012 Nair et al.; licensee BioMed Central Ltd. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f6a4f123-afcf-4484-8d05-ecbfc52c38c4 ER - TY - JOUR TI - The comparison of bitumens from oil sands with different recovery profiles DO - 10.1080/10916466.2010.495960 AU - Woods, J.R. AU - Kung, J. AU - Kingston, D. AU - McCracken, T. AU - Kotlyar, L.S. AU - Sparks, B.D. AU - Mercier, P.H.J. AU - Ng, S. AU - Moran, K. T2 - Petroleum Science and Technology SN - 1091-6466 VL - 30 IS - 22 SP - 2285 EP - 2293 KW - Analytical techniques KW - Athabasca oil sands KW - Bitumen recovery KW - Individual components KW - Mineral matters KW - Recovery profiles KW - Resin content KW - SARA KW - Asphaltenes KW - Centrifugation KW - Nuclear magnetic resonance spectroscopy KW - Oil sands KW - Resins KW - Sulfur KW - Viscosity KW - Bituminous materials AB - It has been proposed that, regardless of origin, the recovery of bitumen from oil sands is related to its viscosity. Asphaltene and resin contents are known to affect the viscosity of bitumen. In this article we compare the composition of solvent-extracted bitumens from several Athabasca oil sands with very different recovery profiles. After careful removal of any associated mineral matter by ultra-centrifugation, each bitumen sample was separated into saturate, aromatic, resin, and asphaltene (SARA) fractions by an enhanced SARA technique. The individual components were then characterized by several complementary analytical techniques, including carbon, nitrogen, nitrogen, sulfur, size exclusion chromatography molecular weight (MW n) plus proton and 13C nuclear magnetic resonance spectroscopy. Based on this comparison, we see no correlation between the recovery of bitumen and its composition. © Crown Copyright. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b3df75fa-523b-41e8-9591-7eb7c8e4df1b ER - TY - JOUR TI - Double pendulum dynamic impact test set-up for ice-grillage collision AU - Alam, Md.S. AU - Daley, C. AU - Colbourne, B. AU - Hermanski, G. AU - Gagnon, B. AU - Bruneau, S. AU - Clarke, G. AU - Quinton, B. T2 - International Conference and Exhibition on Performance of Ships and Structures in Ice 2012, ICETECH 2012 T3 - 10th International Conference and Exhibition on Performance of Ships and Structures in Ice 2012, ICETECH 2012, 17 September 2012 through 20 September 2012, Banff, AB SN - 9781622768011 SP - 294 EP - 297 KW - Double pendulum KW - Dynamic impacts KW - Grillage KW - High impact energy KW - Impact loads KW - Ship structure KW - Test apparatus KW - Vertical positions KW - Exhibitions KW - Pendulums KW - Ships KW - Vehicle performance KW - Ice AB - This paper details the development of a double pendulum dynamic impact test apparatus to study the behavior of collisions between ice and structural grillages, typical of those used in ship structures. Direct collisions between ice and ships involve high impact energy and can cause substantial damage to the ship structure. In order to apply this type of impact energy in a controlled and repeatable way, a double pendulum dynamic impact test frame has been developed. The frame consists of two pendulums: one to cany an ice sample and the other to carry a test grillage structure. The overall size of the apparatus is 4m x 5m x 8m. The live weight of each pendulum is approximately 3000 kg. In operation, the pendulums will be lifted and then released simultaneously to impact each other in a vertical position. The frame is instrumented to measure the impact force and deflection of the grillage. Copynght ©2012 ICETECH 12. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4e36068e-53eb-458e-b1a5-29a4d4fe0648 ER - TY - JOUR TI - Polymer micromolds with near optical quality surface finishes DO - 10.1117/12.908098 AU - Shiu, P.-P. AU - Knopf, G.K. AU - Nikumb, S. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Microfluidics, BioMEMS, and Medical Microsystems X, 23 January 2012 through 24 January 2012, San Francisco, CA SN - 0277-786X SN - 9780819488947 VL - 8251 SP - 82510H KW - Contact less KW - Curved microchannel KW - Demolding KW - Diode-pumped solid-state laser KW - Environmental Monitoring KW - Fabrication process KW - FEM models KW - Finite element models KW - Focused beams KW - High quality surface KW - Intrusion process KW - Manufacturing engineers KW - Material temperature KW - Metallic masks KW - Micro fluidic system KW - Micro-feature KW - Micro-molds KW - Microfeatures KW - micromold KW - Mold-Masters KW - Non-contact KW - Optical qualities KW - Optical quality surfaces KW - Passive components KW - Polymer molds KW - Stress-strain relationships KW - Substrate material KW - Surface finishes KW - BioMEMS KW - Finishing KW - Manufacture KW - Microchannels KW - Microfluidics KW - Microsystems KW - Molds KW - Pumping (laser) KW - Stress-strain curves KW - Substrates KW - Surface properties KW - Functional polymers AB - Disposable microfluidic systems are used to avoid sample contamination in a variety of medical and environmental monitoring applications. A contactless hot intrusion (HI) process for fabricating reusable polymer micromolds with near "optical quality" surface finishes is described in this paper. A metallic hot intrusion mask with the desired microchannels and related passive components is first machined using a tightly focused beam from a diode-pumped solid-state (DPSS) laser. The polymer mold master is then created by pressing the 2D metallic mask onto a polymethylmethacrylate (PMMA) substrate. Since it is a contactless fabrication process the resultant 3D micro-reliefs have near optical quality surface finishes. Unfortunately, the desired micro-relief dimensions (height and width) are not easily related to the hot intrusion process parameters of pressure, temperature, and time exposure profile. A finite element model is introduced to assist the manufacturing engineer in predicting the behavior of the PMMA substrate material as it deforms under heat and pressure during micromold manufacture. The FEM model assumes that thermo-plastics like PMMA become "rubber like" when heated to a temperature slightly above the glass transition temperature. By controlling the material temperature and maintaining its malleable state, it is possible to use the stress-strain relationship to predict the profile dimensions of the imprinted microfeature. Examples of curved microchannels fabricated using PMMA mold masters are presented to illustrate the proposed methodology and verify the finite element model. In addition, the non-contact formation of the micro-reliefs simplifies the demolding process and helps to preserve the high quality surface finishes. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE). DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fe3ddf10-eae4-4b9f-bd96-c63622edfe4d ER - TY - JOUR TI - Gemini high-resolution optical spectrograph conceptual optical design DO - 10.1117/12.925856 AU - Pazder, J. AU - Desaulniers, P. AU - Spanò, P. AU - Szeto, K. AU - Thibault, S. AU - Zhang, H. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Ground-Based and Airborne Instrumentation for Astronomy IV, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491473 VL - 8446 SP - 84462G KW - Echelle spectrograph KW - Gemini telescopes KW - High resolution KW - Volume phase holographic gratings KW - VPH KW - VPHG KW - White pupil relay KW - Astrophysics KW - Conceptual design KW - Fibers KW - Instruments KW - Optical design KW - Optical resolving power KW - Spectrographs AB - The instrument group of the Herzberg Institute of Astrophysics has been commissioned by the Gemini Observatory as one of the three competing organizations to conduct a conceptual design study for a new Gemini High-Resolution Optical Spectrograph (GHOS). This paper outlines the main features of the optical design, including the Cassegrain-mounted science input unit, the bench-mounted spectrograph and the fibre relay system. The predicted imaging performance and efficiency are presented with the design trade offs explored in the study. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 917d65b3-8111-4c93-a0b8-6cb3af900672 ER - TY - JOUR TI - Role of Rydberg states in the photochemical dynamics of ethylene AU - Mori, T. AU - Glover, W.J. AU - Schuurman, M.S. AU - Martinez, T.J. T2 - The Journal of Physical Chemistry A SN - 1089-5639 VL - 116 IS - 11 SP - 3808 EP - 3818 AB - We use the ab initio multiple spawning method with potential energy surfaces and nonadiabatic coupling vectors computed from multistate multireference perturbation theory (MSPT2) to follow the dynamics of ethylene after photoexcitation. We introduce an analytic formulation for the nonadiabatic coupling vector in the context of MSPT2 calculations. We explicitly include the low-lying 3s Rydberg state which has been neglected in previous ab initio molecular dynamics studies of this process. We find that although the 3s Rydberg state lies below the optically bright ππ* state, little population gets trapped on this state. Instead, the 3s Rydberg state is largely a spectator in the photodynamics, with little effect on the quenching mechanism or excited state lifetime. We predict the time-resolved photoelectron spectrum for ethylene and point out the signature of Rydberg state involvement that should be easily observed. © 2011 American Chemical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 84acfe1d-19e2-4693-b9a4-5ee62a98b41f ER - TY - JOUR TI - Identification of genes and gene markers by genomics, genome mapping and comparative proteomics and their relationship to potato tuber qualities AU - Wang-Pruski, G. AU - Babin, S. AU - Murphy, P. AU - Kong, F. AU - Wu, Y. AU - Douglass, K. AU - Murphy, A. AU - De Koeyer, D. AU - Pinto, D. T2 - Acta Horticulturae SN - 0567-7572 SN - 9789066050488 VL - 929 SP - 237 EP - 244 KW - Solanum tuberosum AB - The potato crop is one of the four most important food crops. Since it is a cross-fertilizing, highly heterozygous, and vegetatively-propagated tetraploid species, genetic improvements through traditional breeding are slow, expensive and relatively imprecise. Also, the genetic base in existing cultivars is narrow, making them difficult to use for genetic and genomic analyses. After-cooking darkening (ACD) and enzymatic browning are the major tuber quality defects for both tablestock and processing. This study examined two candidate genes encoding cinnamic acid 4-hydroxylase (C4H) and polyphenol oxidase (PPO), and their functions in relation to ACD. The gene encoding C4H was first cloned from the processing cultivar 'Russet Burbank'. Its gene expression level was shown to be positively related to ACD in a variety of diploid and tetraploid samples tested. Through QTL mapping analysis, we confirmed that the c4h gene, located on chromosome 6, was in one of four QTL regions identified for ACD. PPO is well-known for its involvement in enzymatic browning. This protein was identified through our comparative proteomics study, based on its significant correlation to ACD in a diploid population. This relationship was further examined by real-time qRT-PCR in a larger genetic mapping population. A SNP marker was designed in the coding region of the ppo gene and the association mapping was successfully completed. We believe these two genes are effective candidate markers for breeding for both low ACD and enzymatic browning varieties in potatoes. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c4ecf7c2-5ef5-4a1d-bdfd-8d794fab57fb ER - TY - JOUR TI - Evaluation of mitral valve replacement anchoring in a phantom DO - 10.1117/12.911352 AU - McLeod, A.J. AU - Moore, J. AU - Lang, P. AU - Bainbridge, D. AU - Campbell, G. AU - Jones, D.L. AU - Guiraudon, G.M. AU - Peters, T.M. T2 - Progress in Biomedical Optics and Imaging - Proceedings of SPIE T3 - Medical Imaging 2012: Image-Guided Procedures, Robotic Interventions, and Modeling, 5 February 2012 through 7 February 2012, San Diego, CA SN - 1605-7422 SN - 9780819489654 VL - 8316 SP - 83162Q KW - Anchoring technique KW - Animal studies KW - Beating heart KW - Cardiac surgery KW - Consistent testing KW - Doppler ultrasound KW - Gold standards KW - Image guidance systems KW - Image guided surgery KW - Left atriums KW - Median sternotomy KW - Minimally invasive KW - Mitral annulus KW - Mitral valves KW - Surgical instrument KW - surgical phantom KW - Cardiovascular surgery KW - Medical imaging KW - Prosthetics KW - Robotics KW - Surgical equipment KW - Pumps AB - Conventional mitral valve replacement requires a median sternotomy and cardio-pulmonary bypass with aortic crossclamping and is associated with significant mortality and morbidity which could be reduced by performing the procedure off-pump. Replacing the mitral valve in the closed, off-pump, beating heart requires extensive development and validation of surgical and imaging techniques. Image guidance systems and surgical access for off-pump mitral valve replacement have been previously developed, allowing the prosthetic valve to be safely introduced into the left atrium and inserted into the mitral annulus. The major remaining challenge is to design a method of securely anchoring the prosthetic valve inside the beating heart. The development of anchoring techniques has been hampered by the expense and difficulty in conducting large animal studies. In this paper, we demonstrate how prosthetic valve anchoring may be evaluated in a dynamic phantom. The phantom provides a consistent testing environment where pressure measurements and Doppler ultrasound can be used to monitor and assess the valve anchoring procedures, detecting pararvalvular leak when valve anchoring is inadequate. Minimally invasive anchoring techniques may be directly compared to the current gold standard of valves sutured under direct vision, providing a useful tool for the validation of new surgical instruments. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE). DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8310e3ea-54cd-42b1-94f3-0e6576d69835 ER - TY - JOUR TI - Identification of genes involved in the acetamidino group modification of the flagellin N-Linked glycan of Methanococcus maripaludis DO - 10.1128/JB.06686-11 AU - Jones, G.M. AU - Wu, J. AU - Ding, Y. AU - Uchid, K. AU - Aizaw, S.-I. AU - Robotham, A. AU - Logan, S.M. AU - Kelly, J. AU - Jarrell, K.F. T2 - Journal of Bacteriology SN - 0021-9193 VL - 194 IS - 10 SP - 2693 EP - 2702 KW - ammonia KW - flagellin KW - glycan KW - glycosyltransferase KW - threonine KW - article KW - bacterial gene KW - bacterial growth KW - bacterium mutant KW - carbohydrate synthesis KW - controlled study KW - flagellum KW - gene deletion KW - gene identification KW - gene targeting KW - mass spectrometry KW - Methanococcus maripaludis KW - mmp1081 gene KW - mmp1082 gene KW - mmp1083 gene KW - nonhuman KW - operon KW - priority journal KW - Western blotting KW - Amino Acid Sequence KW - Blotting, Western KW - Carbohydrate Conformation KW - Flagellin KW - Gene Deletion KW - Gene Expression Regulation, Archaeal KW - Methanococcus KW - Mutation KW - Polysaccharides KW - Reverse Transcriptase Polymerase Chain Reaction KW - Archaea KW - Methanococcus maripaludis AB - N-linked glycosylation of protein is a posttranslational modification found in all three domains of life. The flagellin proteins of the archaeon Methanococcus maripaludis are known to be modified with an N-linked tetrasaccharide consisting of N-acetylgalactosamine (GalNAc), a diacetylated glucuronic acid (GlcNAc3NAc), an acetylated and acetamidino-modified mannuronic acid with a substituted threonine group (ManNAc3NAmA6Thr), and a novel terminal sugar residue [(5S)-2-acetamido-2,4-dideoxy-5-O-methyl-α-L-erythro-hexos-5-ulo-1,5-pyranose]. To identify genes involved in biosynthesis of the component sugars of this glycan, three genes, mmp1081, mmp1082, and mmp1083, were targeted for in-frame deletion, based on their annotation and proximity to glycosyltransferase genes known to be involved in assembly of the glycan. Mutants carrying a deletion in any of these three genes remained flagellated and motile. A strain with a deletion of mmp1081 had lower-molecular-mass flagellins in Western blots. Mass spectrometry of purified flagella revealed a truncated glycan with the terminal sugar absent and the threonine residue and the acetamidino group missing from the third sugar. No glycan modification was seen in either the Δmmp1082 or Δmmp1083 mutant grown in complex Balch III medium. However, a glycan identical to the Δmmp1081 glycan was observed when the Δmmp1082 or Δmmp1083 mutant was grown under ammonia-limited conditions. We hypothesize that MMP1082 generates ammonia and tunnels it through MMP1083 to MMP1081, which acts as the amidotransferase, modifying the third sugar residue of the M. maripaludis glycan with the acetamidino group. © 2012, American Society for Microbiology. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0761ecf8-9b64-4876-8c00-15af48aee1dc ER - TY - JOUR TI - Sound transmission loss of orthotropic sandwich panels with soft core and noise control treatment AU - Ghinet, S. AU - Osman, H.A. T2 - 41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012 T3 - 41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012, 19 August 2012 through 22 August 2012, New York, NY SN - 9781627485609 VL - 8 SP - 6413 EP - 6423 KW - Compression deformation KW - Control treatments KW - Dynamic behaviours KW - Membrane behaviours KW - Shearing deformation KW - Sound transmission loss KW - Theoretical approach KW - Transmission loss KW - Acoustic variables control KW - Deformation KW - Sandwich structures KW - Honeycomb structures AB - A new improved model of diffuse field acoustic transmission in symmetrical sandwich panels with thin skins and a soft core is presented in this paper. Generally, asymmetric motion is the only dynamic behaviour which is considered in the modeling of sandwich panels. Bending and membrane behaviour are considered in the skins while the core is assumed to be incompressible over the thickness and experiences only shearing deformations. This set of assumptions is suitable for structures with relatively stiff and thin cores. However, the symmetric mode of motion becomes important for panels with thick and soft cores which exhibit significant compression deformations over the thickness. In this paper, both symmetric and asymmetric modes of motion are considered numerically. Their impact on the transmission loss is addressed in the configuration of a sandwich panel with attached multilayer Noise Control Treatment (NCT). Experimental and literature results are compared with the numerical simulations using the present theoretical approach in order to prove the validity and effectiveness of this approach. Copyright © (2012) by the Institute of Noise Control Engineering (INCE). DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3721471e-a16a-43a3-8608-a0877f4d942a ER - TY - JOUR TI - Identification of a general O-linked protein glycosylation system in Acinetobacter baumannii and its role in virulence and biofilm formation DO - 10.1371/journal.ppat.1002758 AU - Iwashkiw, J.A. AU - Seper, A. AU - Weber, B.S. AU - Scott, N.E. AU - Vinogradov, E. AU - Stratilo, C. AU - Reiz, B. AU - Cordwell, S.J. AU - Whittal, R. AU - Schild, S. AU - Feldman, M.F. T2 - PLoS Pathogens SN - 1553-7366 VL - 8 IS - 6 SP - e1002758 KW - galactose KW - glucose KW - glucuronic acid KW - glycan KW - glycoprotein KW - n acetylglucosamine KW - pentasaccharide KW - bacterial protein KW - glycoprotein KW - membrane protein KW - polysaccharide KW - Acinetobacter baumannii KW - analytic method KW - animal experiment KW - animal model KW - article KW - bacterial genome KW - bacterial growth KW - bacterial strain KW - bacterial virulence KW - bacterium isolate KW - bacterium isolation KW - biofilm KW - carbon nuclear magnetic resonance KW - chromatography KW - controlled study KW - Dictyostelium discoideum KW - galleria mellonella KW - gene sequence KW - heteronuclear single quantum coherence KW - homologous recombination KW - hospital infection KW - in vivo study KW - insect KW - mass spectrometry KW - matrix assisted laser desorption ionization time of flight mass spectrometry KW - nonhuman KW - protein glycosylation KW - proton nuclear magnetic resonance KW - sepsis KW - tandem mass spectrometry KW - two dimensional difference gel electrophoresis KW - zwitterionic hydrophilic interaction chromatography KW - Acinetobacter infection KW - animal KW - Bagg albino mouse KW - confocal microscopy KW - gene inactivation KW - glycosylation KW - metabolism KW - mouse KW - nuclear magnetic resonance spectroscopy KW - pathogenicity KW - virulence KW - Western blotting KW - Acinetobacter baumannii KW - Dictyostelium discoideum KW - Galleria mellonella KW - Hexapoda KW - Acinetobacter baumannii KW - Acinetobacter Infections KW - Animals KW - Bacterial Proteins KW - Biofilms KW - Blotting, Western KW - Gene Knockout Techniques KW - Glycoproteins KW - Glycosylation KW - Magnetic Resonance Spectroscopy KW - Mass Spectrometry KW - Membrane Proteins KW - Mice KW - Mice, Inbred BALB C KW - Microscopy, Confocal KW - Polysaccharides KW - Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization KW - Virulence AB - Acinetobacter baumannii is an emerging cause of nosocomial infections. The isolation of strains resistant to multiple antibiotics is increasing at alarming rates. Although A. baumannii is considered as one of the more threatening "superbugs" for our healthcare system, little is known about the factors contributing to its pathogenesis. In this work we show that A. baumannii ATCC 17978 possesses an O-glycosylation system responsible for the glycosylation of multiple proteins. 2D-DIGE and mass spectrometry methods identified seven A. baumannii glycoproteins, of yet unknown function. The glycan structure was determined using a combination of MS and NMR techniques and consists of a branched pentasaccharide containing N-acetylgalactosamine, glucose, galactose, N-acetylglucosamine, and a derivative of glucuronic acid. A glycosylation deficient strain was generated by homologous recombination. This strain did not show any growth defects, but exhibited a severely diminished capacity to generate biofilms. Disruption of the glycosylation machinery also resulted in reduced virulence in two infection models, the amoebae Dictyostelium discoideum and the larvae of the insect Galleria mellonella, and reduced in vivo fitness in a mouse model of peritoneal sepsis. Despite A. baumannii genome plasticity, the O-glycosylation machinery appears to be present in all clinical isolates tested as well as in all of the genomes sequenced. This suggests the existence of a strong evolutionary pressure to retain this system. These results together indicate that O-glycosylation in A. baumannii is required for full virulence and therefore represents a novel target for the development of new antibiotics. © 2012 Iwashkiw et al. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ec6c0bb8-04a0-4b25-8aba-aeb5977f2a8f ER - TY - JOUR TI - Hippocampal membrane-associated p75 ntr levels are increased in alzheimer's Disease DO - 10.3233/JAD-2012-120115 AU - Chakravarthy, B. AU - Ménard, M. AU - Ito, S. AU - Gaudet, C. AU - Dal Prà, I. AU - Armato, U. AU - Whitfield, J. T2 - Journal of Alzheimer's Disease SN - 1387-2877 VL - 30 IS - 3 SP - 675 EP - 684 KW - amyloid beta protein[1-42] KW - neurotrophin receptor p75 KW - adult KW - aged KW - Alzheimer disease KW - article KW - autopsy KW - brain tissue KW - clinical article KW - cognition KW - controlled study KW - female KW - frontal cortex KW - hippocampus KW - human KW - human cell KW - human cell culture KW - human tissue KW - male KW - mouse KW - neuroblastoma cell KW - nonhuman KW - priority journal KW - Aged KW - Aged, 80 and over KW - Alzheimer Disease KW - Cell Line, Tumor KW - Cell Membrane KW - Female KW - Frontal Lobe KW - Hippocampus KW - Humans KW - Male KW - Middle Aged KW - Neurons KW - Receptor, Nerve Growth Factor KW - Tumor Cells, Cultured AB - The pan-specific p75 neurotrophin receptor (p75 NTR) is believed to play an important role in the pathogenesis of Alzheimer's disease (AD). It is involved in mediating amyloid-β (Aβ) toxicity and stimulating amyloidogenesis. In addition, we have recently shown that stimulating cultured SH-SY5Y human neuroblastoma cells with Aβ 42 increases the level of membrane-associated p75 NTR and that Aβ 42- accumation in two strains of transgenic AD model mice is accompanied by an increased level of hippocampal membrane-associated p75 NTR (Chakravarthy et al. J Alzheimers Dis 19, 915-925, 2010). This raised an important question whether accumulating Aβ 42 in human AD is also accompanied by an increased hippocampal membrane-associated p75 NTR. In this study, using polyclonal and monoclonal antibodies against the p75 NTR receptor's intra-and extracellular domains, we show that indeed the mean level of membrane-associated p75 NTR in the hippocampal formation is significantly higher (~two-fold, p < 0.03) in human AD brains than in identical samples of hippocampal formation in age-matched non-AD human brains. The possible relation of this elevated hippocampal p75 NTR to AD cognitive decline is discussed. © 2012 -IOS Press and the authors. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bcf39eff-1592-4ba5-8e39-bc6d3a11d6ca ER - TY - CHAP TI - Microchip-Based Flow Cytometry in Photonic Sensing: Principles and Applications for Safety and Security Monitoring DO - 10.1002/9781118310212.ch2 AU - Watts, B.R. AU - Zhang, Z. AU - Xu, C.-Q. T2 - Photonic Sensing: Principles and Applications for Safety and Security Monitoring SN - 9780470626955 SP - 59 EP - 87 DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4686b845-48ac-4aad-97a6-024100f82640 ER - TY - JOUR TI - Theory of electronic properties and quantum spin blockade in a gated linear triple quantum dot with one electron spin each DO - 10.1103/PhysRevB.85.085309 AU - Hsieh, C.-Y. AU - Shim, Y.-P. AU - Hawrylak, P. T2 - Physical Review B - Condensed Matter and Materials Physics SN - 1098-0121 VL - 85 IS - 8 SP - 85309 AB - We present a theory of electronic properties and the spin-blockade phenomena in a gated linear triple quantum dot. Quadruple points where four different charge configurations are on resonance, particularly involving (1,1,1) configuration, are considered. In the symmetric case, the central dot is biased to higher energy and a single electron tunnels through the device when the (1,1,1) configuration is resonant with (1,0,1), (2,0,1), (1,0,2) configurations. The electronic properties of a triple quantum dot are described by a Hubbard model containing two orbitals in the two unbiased dots and a single orbital in the biased dot. The transport through the triple-quantum-dot molecule involves both singly and doubly occupied configurations and necessitates the description of the (1,1,1) configuration beyond the Heisenberg model. Exact eigenstates of the triple-quantum-dot molecule with up to three electrons are used to compute current assuming weak coupling to the leads and nonequilibrium occupation of quantum molecule states obtained from the rate equation. The intramolecular relaxation processes due to acoustic phonons and cotunneling with the leads are included, and are shown to play a crucial role in the spin-blockade effect. We find a quantum-interference-based spin-blockade phenomenon at low source-drain bias and a distinct spin blockade due to a trap state at higher bias. We also show that, for an asymmetric quadruple point with (0,1,1), (1,1,1,), (0,2,1), (0,1,2) configurations on resonance, the spin blockade is analogous to the spin blockade in a double quantum dot. ©2012 American Physical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 22e777d0-6c07-4ae7-be3f-1390ec29e894 ER - TY - JOUR TI - An integrated approach for the predictions of the workpiece vibrations during machining of aerospace structure-numerical and experimental validation DO - 10.1115/IMECE2012-89066 AU - Meshreki, M. AU - Kövecses, J. AU - Attia, H. T2 - ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) T3 - ASME 2012 International Mechanical Engineering Congress and Exposition, IMECE 2012, 9 November 2012 through 15 November 2012, Houston, TX SN - 9780791845196 VL - 3 IS - PARTS A, B and C SP - 2067 EP - 2076 KW - Accurate measurement KW - Aerospace structural components KW - Design and optimization KW - Experimental validations KW - High speed machining KW - Holonomic constraints KW - Semi-analytical model KW - Thin walled components KW - Dynamic models KW - Fixtures (tooling) KW - Forecasting KW - Integrated control KW - Thin walled structures KW - Machining AB - Accurate predictions of the workpiece vibrations during high speed machining of aerospace structural components is a critical issue since it affects the accuracy of the final part. For fixture design purposes, and for force predictions, the computational efficiency of the dynamic models predicting the workpiece vibrations is a crucial factor since it affects the cycle time for the design and optimization of the fixtures. Most of the available dynamic models are based on computationally prohibitive techniques, such as finite element analysis. In this work, an integrated approach, based on recently developed semi-analytical models, is presented for the analysis of the effect of the fixture layout on the dynamics of thin-walled structures while taking into account the continuous change of thickness of the workpiece, and the effect of rigid and deformable fixture supports. The developed approach is based on plate models with holonomic constraints and finite stiffness springs. This approach, together with all the developed models and formulations are validated numerically for different workpiece geometries and various types of loading. An experimental study has been performed to validate this approach through the machining of thin-walled components. It was found that this approach led to prediction errors within 10% and more than 20 times reduction in the computation time. The challenge of filtering the effect of the dynamics of the force measurement system from the measured signals was overcome by developing a new hybrid semi-analytical methodology for accurate measurement of the machining forces. Copyright © 2012 by ASME. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3a8d8fb5-6c00-4276-9a81-f5ef210a803b ER - TY - JOUR TI - Strain induced martensite formation in PM nickel steels DO - 10.1179/1743290112Y.0000000014 AU - Tougas, B. AU - Blais, C. AU - Chagnon, F. AU - Pelletier, S. T2 - Powder Metallurgy SN - 0032-5899 VL - 55 IS - 5 SP - 348 EP - 353 KW - Conventional sintering KW - High impact resistance KW - Iron Particles KW - Nickel particles KW - Strain-induced martensite KW - Stress-induced KW - Volume diffusion KW - Volume fraction of retained austenite KW - Martensite KW - Mechanical properties KW - Mechanical testing KW - Nickel KW - Optical microscopy KW - Phase transitions KW - Sintering KW - Steel KW - Powder metallurgy AB - Powder metallurgy (PM) nickel steels are often selected because they have high strength, high impact resistance and good abrasion resistance. The microstructure of slowly cooled PM nickel steels typically contains pearlite, bainite, martensite and a fair volume fraction of retained austenite. Since volume diffusion is really low at conventional sintering temperatures [1120- 1150uC (2050-2100uF)], nickel rich areas are usually found where prior admixed nickel particles were located, i.e. at the surface of iron particles and in sintering necks. Therefore, there is a discrepancy between the rather low mechanical properties of austenite and the high strength of PM nickel steel. Hence, the hypotheses that stress induced or strain induced martensite formation takes place during mechanical testing have been investigated. Results show that martensite forms during mechanical testing, and its final volume fraction is proportional to nickel content. © 2013 Institute of Materials, Minerals and Mining. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f79d3c5e-62c5-4734-85c0-62082ed1b3a0 ER - TY - JOUR TI - Detection of atherosclerotic vascular tissue from optical coherence tomography images DO - 10.1117/12.981916 AU - Prakash, A. AU - Hewko, M. AU - Sowa, M. AU - Sherif, S. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Photonics North 2012, 6 June 2012 through 8 June 2012, Montreal, QC SN - 0277-786X SN - 9780819490902 VL - 8412 SP - 841204 KW - Atherosclerosis KW - Atherosclerotic plaque KW - Automatic classification KW - Automatic classifiers KW - Classification features KW - Coronary artery disease KW - Plaque KW - Spatial gray level dependence matrixes KW - Diseases KW - Feature extraction KW - Tissue KW - Optical tomography AB - Atherosclerotic coronary artery disease continues to be one of the major causes of mortality. Prevention, diagnosis and treatment of atherosclerotic coronary artery disease are dependent on the detection of high risk atherosclerotic plaque. As age is one of the most important risk factors, atherosclerosis worsens steadily with increasing age. Automatic characterization of atherosclerotic plaque using the optical coherence tomography (OCT) images provides a powerful tool to classify patients with high risk plaque. In this study we develop an automatic classifier to detect atherosclerotic plaque in young and old Watanabe heritable hyperlipidemic (WHHL) rabbits, using OCT images without reliance on visual inspection. Our classifier based on texture analysis technique may provide an efficient tool for detecting invisible changes in tissue structure. We extracted a set of 22 statistical textural features for each image using the spatial gray level dependence matrix (SGLDM) method. An optimal scalar feature selection process was carried to select the best discriminating features that employ the Fisher discriminant ratio (FDR) criterion, and cross correlation measure between the pairs of features. Using these optimal features, we formed a combination of 5 best classification features using an exhaustive search method. A combined feature set was finally employed for the classification of plaque. We obtained correct classification rate and validation of 76.67% and 75% respectively. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9e54519a-b86c-47f4-8fb5-5962abd5ba51 ER - TY - JOUR TI - Durability of acrylic sealants applied to joints of autoclaved lightweight concrete walls: evaluation of exposure testing DO - 10.1520/STP154520120003 AU - Miyauchi, H. AU - Lacasse, Michael A. AU - Enomoto, N. AU - Murata, S. AU - Tanaka, K. T2 - ASTM Special Technical Publication T3 - 4th Durability of Building and Construction Sealants and Adhesives, 16 June 2011 through 17 June 2011, Anaheim, CA SN - 0066-0558 SN - 9780803175310 VL - 1545 STP SP - 47 EP - 69 KW - Adhesion joints KW - Climate regions KW - Cohesive failures KW - Exposure period KW - Exposure testing KW - Joint configuration KW - Local temperature KW - Outdoor exposure KW - Outdoor testing KW - Sealant products KW - Subtropical climates KW - Surface cracking KW - Surface cracks KW - Tensile performance KW - Thin layers KW - Wall panels KW - Adhesion KW - Adhesive joints KW - Adhesives KW - Concrete products KW - Concrete testing KW - Construction KW - Deterioration KW - Durability KW - Interfaces (materials) KW - Sun KW - Surface defects KW - Walls (structural partitions) KW - Sealants AB - In Japan acrylic sealants are traditionally the sealant products of choice when specified for use between autoclaved lightweight concrete (ALC) panels. Although, in general terms, the mechanisms of the deterioration of acrylic sealants are well known its long-term durability to outdoor exposure has not, however, been fully investigated. The research described in this paper focuses on the change in the properties and deterioration of acrylic sealant products when exposed to outdoor testing. The two stage project consisted of (i) on-site investigations of deteriorated acrylic sealants that had been placed in external joints of ALC-clad buildings; and (ii) outdoor exposure testing of different types of acrylic sealant in three climate regions located in Japan. The results of the work from the first stage of the study revealed the following. Two-sided adhesion joint configurations installed in deep panel ALC cladding were more reliable than three-sided adhesion joints used for thin panel ALC cladding from the viewpoint of the durability of the sealed joint installed in actual buildings. Most fractures of the sealed joint could be characterized as failure in peel (or thin layer cohesive failures), in which the sealant ruptured at the interface with the ALC substrate to which it was applied. Additionally, in 47 of 62 locations surveyed, surface cracks were apparent on the coating that had been applied to protect the sealant. The second stage of the project focused on the degree of deterioration of coated and non-coated acrylic sealants subjected to outdoor exposure testing in a cold, a warm, and a subtropical climate. Results from this stage showed that aging of the sealant, as determined by the degree of surface cracking, expectedly depended on the local temperature and the respective degree of exposure to solar radiation. It was determined that the longer the exposure period, the lower the tensile performance of the acrylic sealants. The elongation of three-sided adhesive joint configurations after 5 years exposure testing decreased remarkably and their maximum elongation was less than 50%. A significant number of sealed joints after 5 years ofexposure had ALC substrate failure DA - 2012/07/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 636f11f2-e8fb-4923-91f0-93beb3a122fb ER - TY - JOUR TI - A fuzzy logic based approach to expressing and reasoning with uncertain knowledge on the semantic web DO - 10.1007/978-3-642-27534-0_11 AU - Zhao, J. AU - Boley, H. AU - Du, W. T2 - Studies in Computational Intelligence SN - 1860-949X SN - 9783642275333 VL - 399 SP - 167 EP - 181 AB - The necessity of dealing with uncertain knowledge has arisen from Semantic Web applications in different areas. Handling uncertainty thus becomes one of the key research directions in the Semantic Web community. This paper introduces a fuzzy logic based approach which extends the classic Description Logic with Zadeh semantics to deal with uncertain knowledge about concepts and roles as well as instances of concepts and roles. Uncertain knowledge representation and the reasoning algorithm for consistency checking of a fuzzy knowledge base are addressed in detail. This paper also discusses complexity issues of the reasoning problem. © 2012 Springer-Verlag GmbH Berlin Heidelberg. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 113c4e9d-51c1-4cf1-9022-78baf72eeede ER - TY - JOUR TI - Terahertz quantum cascade lasers based on phonon scattering assisted injection and extraction AU - Fathololoumi, S. AU - Dupont, E. AU - Wasilewski, Z.R. AU - Aers, G. AU - Laframboise, S.R. AU - Lindskog, M. AU - Wacker, A. AU - Ban, D. AU - Liu, H.C. T2 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012 T3 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012, 6 May 2012 through 11 May 2012, San Jose, CA SN - 9781467318396 SP - 6325968 KW - Density matrix KW - Design procedure KW - Fabricated device KW - Generic algorithm KW - Terahertz quantum-cascade lasers KW - Computer programming KW - Phonons KW - Quantum cascade lasers KW - Lasers AB - A novel terahertz quantum cascade laser, based on consecutive phonon-photon-phonon emissions, is proposed. The design procedure used a density matrix based figure-of-merit and a generic algorithm approach; the fabricated device lased up to 138 K. © 2012 OSA. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ccf68b51-2b1f-4ddd-aab7-65a635d8e01d ER - TY - JOUR TI - The ACS Fornax Cluster Survey. VI. the nuclei of early-type galaxies in the Fornax Cluster DO - 10.1088/0067-0049/203/1/5 AU - Turner, M.L. AU - Côté, P. AU - Ferrarese, L. AU - Jordán, A. AU - Blakeslee, J.P. AU - Mei, S. AU - Peng, E.W. AU - West, M.J. T2 - Astrophysical Journal, Supplement Series SN - 0067-0049 VL - 203 IS - 1 SP - 5 AB - The Advanced Camera for Surveys (ACS) Fornax Cluster Survey is a Hubble Space Telescope program to image 43 early-type galaxies in the Fornax cluster, using the F475W and F850LP bandpasses of the ACS. We employ both one-dimensional and two-dimensional techniques to characterize the properties of the stellar nuclei in these galaxies, defined as the central "luminosity excesses", relative to a Sersic model fitted to the underlying host. We find 72% ± 13% of our sample (31 galaxies) to be nucleated, with only three of the nuclei offset by more than 05 from their galaxy photocenter, and with the majority of nuclei having colors bluer than their hosts. The nuclei are observed to be larger, and brighter, than typical Fornax globular clusters and to follow different structural scaling relations. A comparison of our results to those from the ACS Virgo Cluster Survey reveals striking similarities in the properties of the nuclei belonging to these different environments. We briefly review a variety of proposed formation models and conclude that, for the low-mass galaxies in our sample, the most important mechanism for nucleus growth is probably infall of star clusters through dynamical friction, while for higher mass galaxies, gas accretion triggered by mergers, accretions, and tidal torques is likely to dominate, with the relative importance of these two processes varying smoothly as a function of galaxy mass. Some intermediate-mass galaxies in our sample show a complexity in their inner structure that may be the signature of the "hybrid nuclei" that arose through parallel formation channels. © 2012. The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2b097a9d-ff8e-469f-a1cf-341923b625b6 ER - TY - JOUR TI - Corrosion sensor development for condition-based maintenance of aircraft DO - 10.1155/2012/684024 AU - Rinaldi, G. AU - Huber, T. AU - McIntosh, H. AU - Lebrun, L. AU - Ding, H. AU - Weber, J. T2 - International Journal of Aerospace Engineering SN - 1687-5966 SP - 684024 AB - Aircraft routinely operate in atmospheric environments that, over time, will impact their structural integrity. Material protection and selection schemes notwithstanding, recurrent exposure to chlorides, pollution, temperature gradients, and moisture provide the necessary electrochemical conditions for the development and profusion of corrosion in aircraft structures. For aircraft operators, this becomes an important safety matter as corrosion found in a given aircraft must be assumed to be present in all of that type of aircraft. This safety protocol and its associated unscheduled maintenance requirement drive up the operational costs of the fleet and limit the availability of the aircraft. Hence, there is an opportunity at present for developing novel sensing technologies and schemes to aid in shifting time-based maintenance schedules towards condition-based maintenance procedures. In this work, part of the ongoing development of a multiparameter integrated corrosion sensor is presented. It consists of carbon nanotube/polyaniline polymer sensors and commercial-off-the-shelf sensors. It is being developed primarily for monitoring environmental and material factors for the purpose of providing a means to more accurately assess the structural integrity of aerospace aluminium alloys through fusion of multiparameter sensor data. Preliminary experimental test results are presented for chloride ion concentration, hydrogen gas evolution, humidity variations, and material degradation. Copyright © 2012 Gino Rinaldi et al. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e322bfb3-32ed-4507-a481-c4a1791f59e8 ER - TY - JOUR TI - Disulfide linkage engineering for improving biophysical properties of human VH domains DO - 10.1093/protein/gzs055 AU - Kim, D.Y. AU - Kandalaft, H. AU - Ding, W. AU - Ryan, S. AU - Van Faassen, H. AU - Hirama, T. AU - Foote, S.J. AU - MacKenzie, R. AU - Tanha, J. T2 - Protein Engineering, Design and Selection SN - 1741-0126 VL - 25 IS - 10 SP - 581 EP - 589 KW - Affinity reagents KW - Biophysical properties KW - Conformational change KW - Disulfide linkages KW - Heavy chain KW - Heavy-chain antibodies KW - Human antibodies KW - Model domains KW - Multi-angle light scatterings KW - Therapeutic potentials KW - thermostability KW - Variable domain KW - Agglomeration KW - Amino acids KW - Antibodies KW - Libraries KW - Turbidity KW - Sulfur compounds KW - antibody KW - cysteine KW - disulfide KW - heavy chain antibody variable domain KW - protein A KW - unclassified drug KW - amino acid substitution KW - article KW - Artiodactyla KW - binding affinity KW - biophysics KW - circular dichroism KW - covalent bond KW - disulfide linkage KW - gel permeation chromatography KW - human KW - mass spectrometry KW - molecular cloning KW - priority journal KW - protein engineering KW - protein expression KW - thermostability KW - turbidity KW - Amino Acid Sequence KW - Amino Acid Substitution KW - Disulfides KW - Humans KW - Immunoglobulin Heavy Chains KW - Immunoglobulin Variable Region KW - Molecular Sequence Data KW - Protein Conformation KW - Protein Engineering KW - Protein Stability KW - Sequence Alignment KW - Temperature KW - Camelidae AB - To enhance their therapeutic potential, human antibody heavy chain variable domains (VHs) would benefit from increased thermostability. The highly conserved disulfide linkage that connects Cys23 and Cys104 residues in the core of VH domains is crucial to their stability and function. It has previously been shown that the introduction of a second disulfide linkage can increase the thermostability of camelid heavy-chain antibody variable domains (VHHs). Using four model domains we demonstrate that this strategy is also applicable to human VH domains. The introduced disulfide linkage, formed between Cys54 and Cys78 residues, increased the thermostability of VHs by 1418°C. In addition, using a novel hexa-histidine capture technology, circular dichroism, turbidity, size exclusion chromatography and multiangle light scattering measurements, we demonstrate reduced VH aggregation in domains with the Cys54Cys78 disulfide linkage. However, we also found that the engineered disulfide linkage caused conformational changes, as indicated by reduced binding of the VHs to protein A. This indicates that it may be prudent to use the synthetic VH libraries harboring the engineered disulfide linkage before screening for affinity reagents. Such strategies may increase the number of thermostable binders. © 2012 The Author. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 058a7ad7-aa5d-46f3-bb92-5b6891a2747d ER - TY - JOUR TI - Complex Faraday depth structure of active galactic nuclei as revealed by broad-band radio polarimetry DO - 10.1111/j.1365-2966.2012.20554.x AU - O'Sullivan, S.P. AU - Brown, S. AU - Robishaw, T. AU - Schnitzeler, D.H.F.M. AU - Mcclure-Griffiths, N.M. AU - Feain, I.J. AU - Taylor, A.R. AU - Gaensler, B.M. AU - Landecker, T.L. AU - Harvey-Smith, L. AU - Carretti, E. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 421 IS - 4 SP - 3300 EP - 3315 AB - We present a detailed study of the Faraday depth structure of four bright (>1 Jy), strongly polarized, unresolved radio-loud quasars. The Australia Telescope Compact Array (ATCA) was used to observe these sources with 2 GHz of instantaneous bandwidth from 1.1 to 3.1 GHz. This allowed us to spectrally resolve the polarization structure of spatially unresolved radio sources, and by fitting various Faraday rotation models to the data, we conclusively demonstrate that two of the sources cannot be described by a simple rotation measure (RM) component modified by depolarization from a foreground Faraday screen. Our results have important implications for using background extragalactic radio sources as probes of the Galactic and intergalactic magneto-ionic media as we show how RM estimations from narrow-bandwidth observations can give erroneous results in the presence of multiple interfering Faraday components. We postulate that the additional RM components arise from polarized structure in the compact inner regions of the radio source itself and not from polarized emission from galactic or intergalactic foreground regions. We further suggest that this may contribute significantly to any RM time variability seen in RM studies on these angular scales. Follow-up, high-sensitivity very long baseline interferometry (VLBI) observations of these sources will directly test our predictions. © 2012 CSIRO. Monthly Notices of the Royal Astronomical Society © 2012 RAS. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 05e0b03f-5e88-4e8c-b5e8-4056127c69e6 ER - TY - JOUR TI - Multivalent display of single-domain antibodies DO - 10.1007/978-1-61779-968-6-27 AU - Zhang, J. AU - MacKenzie, C.R. T2 - Methods in Molecular Biology SN - 1064-3745 SN - 9781617799679 VL - 911 SP - 445 EP - 456 KW - carcinoembryonic antigen related cell adhesion molecule 1 KW - nanobody KW - pentabody ES1 KW - plasmid vector KW - unclassified drug KW - nanobody KW - antigen binding KW - antigen recognition KW - article KW - carcinoma cell KW - controlled study KW - drug purification KW - drug synthesis KW - gene expression KW - human KW - human cell KW - nucleotide sequence KW - phage display KW - priority journal KW - amino acid sequence KW - animal KW - Artiodactyla KW - cell surface display KW - chemistry KW - gene expression KW - gene library KW - gene order KW - genetics KW - immunoglobulin variable region KW - immunology KW - methodology KW - molecular genetics KW - protein binding KW - tumor cell line KW - Amino Acid Sequence KW - Animals KW - Camelids, New World KW - Cell Line, Tumor KW - Cell Surface Display Techniques KW - Gene Expression KW - Gene Library KW - Gene Order KW - Humans KW - Immunoglobulin Variable Region KW - Molecular Sequence Data KW - Protein Binding KW - Single-Domain Antibodies AB - Antigen-binding fragments, such as single-domain antibodies (sdAbs), can now be readily isolated by in vitro technologies. Antibody fragment libraries derived from immune or nonimmune sources are presented in a molecular display format, typically phage display, and binders to individual antigens are selected from the libraries by a so-called panning process. Nonimmune libraries can serve as sources of binders to a wide range of targets but yield antigen-binding fragments that generally have much lower affinities than those obtained from immune sources. Here we describe a strategy for constructing pentameric sdAbs termed pentabodies. Pentamerization introduces avidity which can greatly enhance the binding of low affinity sdAbs to antigens presented on surfaces. © 2012 Springer Science+Business Media, LLC. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b82ea504-ebdc-41a0-82c8-969f6e608e89 ER - TY - JOUR TI - Invasive potential of nonencapsulated disease isolates of neisseria: Meningitidis DO - 10.1128/IAI.00293-12 AU - Johswich, K.O. AU - Zhou, J. AU - Law, D.K.S. AU - St. Michael, S.F. AU - McCaw, S.E. AU - Jamieson, F.B. AU - Cox, A.D. AU - Tsang, R.S.W. AU - Gray-Owen, S.D. T2 - Infection and Immunity SN - 0019-9567 VL - 80 IS - 7 SP - 2346 EP - 2353 KW - cytidine phosphate n acetylneuraminic acid KW - lipooligosaccharide KW - animal experiment KW - animal model KW - article KW - bacterial gene KW - bacterial membrane KW - bacterial strain KW - bacterial virulence KW - bacterium isolate KW - blood culture KW - Canada KW - controlled study KW - gene locus KW - mass spectrometry KW - meningococcosis KW - mortality KW - mouse KW - Neisseria meningitidis KW - nonhuman KW - phenotype KW - polymerase chain reaction KW - priority journal KW - serology KW - sialylation KW - Animals KW - Bacterial Capsules KW - Canada KW - Complement System Proteins KW - Disease Models, Animal KW - Female KW - Genes, Bacterial KW - Humans KW - Male KW - Meningococcal Infections KW - Mice KW - Mice, Inbred C57BL KW - Neisseria meningitidis KW - Peritonitis KW - Polymerase Chain Reaction KW - Rabbits KW - Serotyping KW - Survival Analysis KW - Virulence Factors AB - The capsule of Neisseria meningitidis is the major virulence factor that enables this bacterium to overcome host immunity elicited by complement and phagocytes, rendering it capable of surviving in blood. As such, nonencapsulated N. meningitidis isolates are generally considered nonpathogenic. Here, we consider the inherent virulence of two nonencapsulated N. meningitidis isolates obtained from our national surveillance of infected blood cultures in Canada. Capsule deficiency of both strains was confirmed by serology and PCR for the ctrA to ctrD genes and siaA to siaC genes, as well as siaD genes specific to serogroups B, C, Y, and W135. In both strains, the capsule synthesis genes were replaced by the capsule null locus, cnl-2. In accordance with a lack of capsule, both strains were fully susceptible to killing by both human and baby rabbit complement. However, in the presence of cytidine-5' monophospho-N-acetylneuraminic acid (CMP-NANA), allowing for lipooligosaccharide (LOS) sialylation, a significant increase of resistance to complement killing was observed. Mass spectrometry of purified LOS did not reveal any uncommon modifications that would explain their invasive phenotype. Finally, in a mouse intraperitoneal challenge model, these nonencapsulated isolates displayed enhanced virulence relative to an isogenic mutant of serogroup B strain MC58 lacking capsule (MC58ΔsiaD). Virulence of all nonencapsulated isolates tested was below that of encapsulated serogroup B strains MC58 and B16B6. However, whereas no mortality was observed with MC58ΔsiaD, 5/10 mice succumbed to infection with strain 2275 and 2/11 mice succumbed to strain 2274. Our results suggest the acquisition of a new virulence phenotype by these nonencapsulated strains. © 2012, American Society for Microbiology. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 946c9c19-0687-45a0-99c7-32de2b75d0d5 ER - TY - CHAP TI - Cyclic Dwell Fatigue Behaviour of Single Crystal Ni-Base Superalloys with/without Rhenium DO - 10.1002/9781118516430.ch55 AU - Yandt, S. AU - Wu, X.-J. AU - Tsuno, N. AU - Sato, A. T2 - Superalloys 2012 SN - 9780470943205 SP - 501 EP - 508 AB - In this study, compressive dwell (C-D) and no-dwell (N-D) lowcycle fatigue (LCF) behaviours of several single crystal Ni-base superalloys, including CMSX-4, LSC-11 and LSC-15, were studied under strain-controlled zero-compression (R, = -co) loading at 1100°C. LSC-11 and LSC-15 are new alloys developed by IHI Corporation, Japan with 0.8 wt% Re and without Re addition, respectively, as reduced-cost alternatives to the second generation single crystal Ni-base superalloys. The fatigue experiments were conducted with or without a two-minute dwell (hold) in compression and total strain ranges of 0.7%, 0.6% and 0.5% on uncoated specimens in the [001] orientation. Examination of the cyclic stress-strain behavior revealed that the initially compressive mean stress relaxed to approximately zero stress in N-D tests, while compressive hold resulted in the development of a tensile mean stress during C-D fatigue. Cyclic stress softening was observed under all test conditions. Microstructural analysis of tested specimens showed that N-D fatigue promoted isotropic coarsening of the γ' precipitates, while C-D loading resulted in the formation of discontinuous γ' rafting parallel to the loading direction. Fatigue cracks initiated from the specimen surface from regions of localized oxide attack. All alloys were compressive dwell sensitive. C-D fatigue lives were 4-15x shorter than N-D when the same alloys were considered. CMSX-4 exhibited 1.5-3* N-D fatigue life advantage over alloys LSC-11 and LSC-15. Under C-D fatigue the life advantage of CMSX-4 was 20-50% greater than alloys LSC-11 and LSC-15. The differences in these behaviours could be attributed to Re content and oxidation. © 2012 The Minerals, Metals, & Materials Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 70a5d643-fd75-403b-bc54-626b1dde8af4 ER - TY - JOUR TI - MAGMO: Coherent magnetic fields in the star-Forming regions of the Carina-Sagittarius spiral arm tangent DO - 10.1111/j.1365-2966.2012.21722.x AU - Green, J.A. AU - McClure-Griffiths, N.M. AU - Caswell, J.L. AU - Robishaw, T. AU - Harvey-Smith, L. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 425 IS - 4 SP - 2530 EP - 2547 AB - We present the pilot results of the 'MAGMO' project, targeted observations of ground-state hydroxyl masers towards sites of 6.7-GHz methanol maser emission in the Carina-Sagittarius spiral arm tangent, Galactic longitudes 280° to 295°. The 'MAGMO' project aims to determine if Galactic magnetic fields can be traced with Zeeman splitting of masers associated with star formation. Pilot observations of 23 sites of methanol maser emission were made, with the detection of ground-state hydroxyl masers towards 11 of these and six additional offset sites. Of these 17 sites, nine are new detections of sites of 1665-MHz maser emission, three of them accompanied by 1667-MHz emission. More than 70 per centof the maser features have significant circular polarization, whilst only ~10 per cent have significant linear polarization (although some features with up to 100 per cent linear polarization are found). We find 11 Zeeman pairs across six sites of high-mass star formation with implied magnetic field strengths between -1.5 and +3.8 mG and a median field strength of +1.6 mG. Our measurements of Zeeman splitting imply that a coherent field orientation is experienced by the maser sites across a distanc of 5.3 ± 2.0 kpc within the Carina-Sagittarius spiral arm tangent. © 2012 CSIRO. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e0a8856b-08dc-453e-a389-71272953e0c2 ER - TY - JOUR TI - Isolation and characterization of clostridium difficile toxin-specific single-domain antibodies DO - 10.1007/978-1-61779-968-6-14 AU - Hussack, G. AU - Arbabi-Ghahroudi, M. AU - MacKenzie, C.R. AU - Tanha, J. T2 - Methods in Molecular Biology SN - 1064-3745 SN - 9781617799679 VL - 911 SP - 211 EP - 239 KW - Clostridium difficile toxin A KW - Clostridium difficile toxin B KW - epitope KW - nanobody KW - recombinant antibody KW - bacterial toxin KW - epitope KW - immunoglobulin G KW - immunoglobulin heavy chain KW - immunoglobulin M KW - animal experiment KW - antibody affinity KW - antibody production KW - antibody specificity KW - article KW - binding affinity KW - camel KW - Clostridium difficile KW - complementarity determining region KW - human KW - immunization KW - male KW - molecular weight KW - nonhuman KW - priority journal KW - animal KW - Artiodactyla KW - blood KW - cell surface display KW - immunology KW - isolation and purification KW - peptide library KW - Animals KW - Antibody Affinity KW - Antibody Specificity KW - Bacterial Toxins KW - Camelids, New World KW - Cell Surface Display Techniques KW - Clostridium difficile KW - Epitopes KW - Immunoglobulin G KW - Immunoglobulin Heavy Chains KW - Immunoglobulin M KW - Male KW - Peptide Library KW - Single-Domain Antibodies AB - Camelidae single-domain antibodies (VHHs) are a unique class of small binding proteins that are promising inhibitors of targets relevant to infection and immunity. With VHH selection from hyperimmunized phage display libraries now routine and the fact that VHHs possess long, extended complementarity- determining region (CDR3) loop structures that can access traditionally immunosilent epitopes, VHH-based inhibition of targets such as bacterial toxins are being explored. Toxin A and toxin B are high molecular weight exotoxins (308 kDa and 269 kDa, respectively) secreted by Clostridium difficile that are the causative agents of C. difficile-associated diseases in humans and in animals. Here, we provide protocols for the rapid generation of C. difficile toxin A-and toxin B-specific VHHs by llama immunization and recombinant antibody/phage display technology approaches and for further characterization of the VHHs with respect to toxin-binding affinity and specificity and the conformational nature of their epitopes. © 2012 Springer Science+Business Media, LLC. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2cfdb556-99b4-40c8-8adc-f847c3b640f7 ER - TY - JOUR TI - Mechanisms of two-color laser-induced field-free molecular orientation DO - 10.1103/PhysRevLett.109.113001 AU - Spanner, Michael AU - Patchkovskii, Serguei AU - Frumker, Eugene AU - Corkum, Paul T2 - Physical Review Letters SN - 0031-9007 VL - 109 IS - 11 SP - 113001 KW - CO molecule KW - Dominant mechanism KW - Field-free orientation KW - Hyper-polarizability KW - Ionization mechanisms KW - Ionization thresholds KW - Laser induced KW - Orientation mechanism KW - Two-color KW - Ionization KW - Molecular orientation AB - Two mechanisms of two-color (ω+2ω) laser-induced field-free molecular orientation, based on the hyperpolarizability and ionization depletion, are explored and compared. The CO molecule is used as a computational example. While the hyperpolarizability mechanism generates small amounts of orientation at intensities below the ionization threshold, ionization depletion quickly becomes the dominant mechanism as soon as ionizing intensities are reached. Only the ionization mechanism leads to substantial orientation (e.g., on the order of cosθ0.1). For intensities typical of laser-induced molecular alignment and orientation experiments, the two mechanisms lead to robust, characteristic timings of the field-free orientation wave-packet revivals relative to the alignment revivals and the revival time. The revival timings can be used to detect the active orientation mechanism experimentally. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : df0d4079-a8a3-4263-bda1-3cb10df29b58 ER - TY - JOUR TI - VLBI for Gravity Probe B. VI. the orbit of im Pegasi and the location of the source of radio emission DO - 10.1088/0067-0049/201/1/6 AU - Ransom, R.R. AU - Bartel, N. AU - Bietenholz, M.F. AU - Lebach, D.E. AU - Lestrade, J.-F. AU - Ratner, M.I. AU - Shapiro, I.I. T2 - Astrophysical Journal, Supplement Series SN - 0067-0049 VL - 201 IS - 1 SP - 6 AB - We present a physical interpretation for the locations of the sources of radio emission in IM Pegasi (IMPeg, HR8703), the guide star for the NASA/Stanford relativity mission Gravity Probe B. This emission is seen in each of our 35 epochs of 8.4 GHz very long baseline interferometry observations taken from 1997 to 2005. We found that the mean position of the radio emission is at or near the projected center of the primary to within about 27% of its radius, identifying this active star as the radio emitter. The positions of the radio brightness peaks are scattered across the disk of the primary and slightly beyond, preferentially along an axis with position angle, P.A.= -38° ± 8°, which is closely aligned with the sky projections of the orbit normal (P.A.= -495 ± 86) and the expected spin axis of the primary. Comparison with simulations suggests that brightness peaks are 3.6 +0.4 - 0.7 times more likely to occur (per unit surface area) near the pole regions of the primary (latitude, |λ| ≥ 70°) than near the equator (|λ| ≤ 20°), and to also occur close to the surface with 2/3 of them at altitudes not higher than 25% of the radius of the primary. © 2012. The American Astronomical Society. All rights reserved.. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 43f2f664-0e68-4ec3-b135-56d1c28d97c5 ER - TY - JOUR TI - Advanced vibration suppression algorithms in adaptive optics systems DO - 10.1364/JOSAA.29.000185 AU - Correia, C. AU - Véran, J.-P. AU - Herriot, G. T2 - Journal of the Optical Society of America A: Optics and Image Science, and Vision SN - 1084-7529 VL - 29 IS - 3 SP - 185 EP - 194 KW - Adaptive optics systems KW - Extremely Large Telescopes KW - Frame rate KW - Guide star KW - Keck observatory KW - Linear quadratic Gaussian KW - Monte Carlo Simulation KW - Multi rate KW - Multi-rate algorithm KW - Natural guide star KW - Peak vibrations KW - Peak widths KW - Sampling frequencies KW - Signal to noise KW - Sky coverage KW - Temporal sampling KW - Tip-tilt KW - Tomographic KW - Upsampling KW - Vibration suppression KW - Algorithms KW - Monte Carlo methods KW - Stars KW - Telescopes KW - Optical telescopes AB - Vibration suppression in astronomical adaptive optics (AO) systems has gathered great attention in the context of next-generation instrumentation for current telescopes and future Extremely Large Telescopes. Laser tomographic AO systems require natural guide stars to measure the low-order modes such as tip-tilt (TT) and TT-anisoplanatism. To increase the sky coverage, the guide stars are often faint, thus requiring lower temporal sampling frequencies to work on a more favorable signal-to-noise regime. Such sampling frequencies can be of the order of, or even lower than, the range of frequencies where vibrations are likely to appear. Ideally, vibrations affecting the loworder modes could be corrected at the higher laser loop frame rate using an upsampling procedure. This paper compares the most relevant solutions proposed hitherto to a novel multirate algorithm using the linear-quadratic-Gaussian (LQG) approach capable of upsampling the correction to further reduce the impact of vibrations. Results from numerical Monte Carlo simulations span a large range of parameters from pure sinusoids to relatively broad peak vibrations, covering the likely-to-be signals in a realistic AO system. The improvement is shown at sampling frequencies from 20 to 800 Hz, including below the vibration itself, in the example of 29.5 Hz on a Thirty Meter Telescope-like scenario. The multirate LQG ensures the least residual for both faint and bright stars for all the peak widths considered based on telemetry from the Keck Observatory. © 2012 Optical Society of America. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : eb32e642-68db-4632-aca4-c4921bb8592f ER - TY - JOUR TI - VLBI for Gravity Probe B. IV. A new astrometric analysis technique and a comparison with results from other techniques DO - 10.1088/0067-0049/201/1/4 AU - Lebach, D.E. AU - Bartel, N. AU - Bietenholz, M.F. AU - Campbell, R.M. AU - Gordon, D. AU - Lederman, J.I. AU - Lestrade, J.-F. AU - Ransom, R.R. AU - Ratner, M.I. AU - Shapiro, I.I. T2 - Astrophysical Journal, Supplement Series SN - 0067-0049 VL - 201 IS - 1 SP - 4 AB - When very long baseline interferometry (VLBI) observations are used to determine the position or motion of a radio source relative to reference sources nearby on the sky, the astrometric information is usually obtained via (1) phase-referenced maps or (2) parametric model fits to measured fringe phases or multiband delays. In this paper, we describe a "merged" analysis technique which combines some of the most important advantages of these other two approaches. In particular, our merged technique combines the superior model-correction capabilities of parametric model fits with the ability of phase-referenced maps to yield astrometric measurements of sources that are too weak to be used in parametric model fits. We compare the results from this merged technique with the results from phase-referenced maps and from parametric model fits in the analysis of astrometric VLBI observations of the radio-bright star IMPegasi (HR8703) and the radio source B2252+172 nearby on the sky. In these studies we use central-core components of radio sources 3C454.3 and B2250+194 as our positional references. We obtain astrometric results for IMPeg with our merged technique even when the source is too weak to be used in parametric model fits, and we find that our merged technique yields astrometric results superior to the phase-referenced mapping technique. We used our merged technique to estimate the proper motion and other astrometric parameters of IMPeg in support of the NASA/Stanford Gravity Probe B mission. © 2012. The American Astronomical Society. All rights reserved.. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 03bc11bf-2b28-4643-9d8b-eed06b872acf ER - TY - JOUR TI - Thermodynamic stability of structure H hydrates based on the molecular properties of large guest molecules DO - 10.3390/en5020459 AU - Tezuka, K. AU - Taguchi, T. AU - Alavi, S. AU - Sum, A.K. AU - Ohmura, R. T2 - Energies SN - 1996-1073 VL - 5 IS - 2 SP - 459 EP - 465 KW - Clathrate hydrate KW - Equilibrium pressure KW - Gasphase KW - Guest molecules KW - Hydrate stabilities KW - Large molecule guest substance KW - Molecular properties KW - Molecular size KW - Molecule sizes KW - Structure H-hydrate KW - Gas hydrates KW - Gases KW - Hydration KW - Methane KW - Phase equilibria KW - Thermodynamic stability KW - Molecules AB - This paper report analyses of thermodynamic stability of structure-H clathrate hydrates formed with methane and large guest molecules in terms of their gas phase molecular sizes and molar masses for the selection of a large guest molecule providing better hydrate stability. We investigated the correlation among the gas phase molecular sizes, the molar masses of large molecule guest substances, and the equilibrium pressures. The results suggest that there exists a molecular-size value for the best stability. Also, at a given molecule size, better stability may be available when the large molecule guest substance has a larger molar mass. © 2012 by the authors; licensee MDPI, Basel, Switzerland. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d4718ac2-37b3-4241-8318-9eb15cc82688 ER - TY - JOUR TI - Strong-field ionization and high-order-harmonic generation during polyatomic molecular dynamics of N 2O 4 DO - 10.1103/PhysRevA.85.033426 AU - Spanner, M. AU - Mikosch, J. AU - Boguslavskiy, A.E. AU - Murnane, M.M. AU - Stolow, A. AU - Patchkovskii, S. T2 - Physical Review A - Atomic, Molecular, and Optical Physics SN - 1050-2947 VL - 85 IS - 3 SP - 33426 KW - Bound state KW - Coincidence measurement KW - Computational results KW - Grid-based approach KW - Interchannel coupling KW - Ionic state KW - Multi-electron KW - Polyatomic molecular dynamics KW - Polyatomic molecules KW - Radiating dipole KW - Single electron KW - Single state KW - Single-molecule KW - Strong field ionization KW - Time-dependent KW - Vibrational amplitudes KW - Harmonic generation KW - Ionization KW - Molecular dynamics AB - We present state-of-the-art ab initio-type computations of strong-field ionization (SFI) and the single-molecule response contribution to high-order-harmonic generation (HHG) in the polyatomic molecule N 2O 4. The numerical method uses a mixed orbital- and grid-based approach to model the multielectron bound states and single-electron continuum. The effects of ionic-core attraction and Coulomb-mediated interchannel coupling are rigorously included. We show that full-dimensionality time-dependent multielectron computations of SFI and HHG in polyatomic molecules are now feasible. The computational results indicate that (a) SFI yields in N 2O 4 are dominated by a single ionic state (the A g state), and are strongly modulated by the N-N stretch coordinate; and (b) the HHG radiating dipole as a function of the N 2O 4 N-N stretch is dominated by the same, single state. The molecular-beam coincidence measurements presented here support the computational results. Due to the differences in the estimated vibrational amplitude, however, the computations are not in full agreement with previous HHG data. ©2012 American Physical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3d216298-0e8a-49a8-8090-2d29cbaff483 ER - TY - JOUR TI - Crystal structure of a human single domain antibody dimer formed through V H-V H non-covalent interactions DO - 10.1371/journal.pone.0030149 AU - Baral, T.N. AU - Chao, S.-Y. AU - Li, S. AU - Tanha, J. AU - Arbabi-Ghahroudi, M. AU - Zhang, J. AU - Wang, S. T2 - PLoS ONE SN - 1932-6203 VL - 7 IS - 1 SP - e30149 KW - epidermal growth factor receptor 2 single domain antibody Gr3 KW - epidermal growth factor receptor 2 single domain antibody Gr6 KW - epidermal growth factor receptor antibody KW - homodimer KW - unclassified drug KW - antibody KW - epidermal growth factor receptor 2 KW - HER2 protein, human KW - article KW - controlled study KW - covalent bond KW - crystal structure KW - dimerization KW - gel permeation chromatography KW - hydrophobicity KW - immunoglobulin variable region KW - molecular cloning KW - molecular interaction KW - molecular library KW - phage display KW - protein analysis KW - protein assembly KW - protein isolation KW - surface plasmon resonance KW - thermostability KW - amino acid sequence KW - antibody specificity KW - chemical phenomena KW - chemical structure KW - chemistry KW - human KW - immunology KW - metabolism KW - molecular genetics KW - protein binding KW - protein multimerization KW - protein secondary structure KW - protein tertiary structure KW - solution and solubility KW - transition temperature KW - X ray crystallography KW - Amino Acid Sequence KW - Antibodies KW - Antibody Specificity KW - Crystallography, X-Ray KW - Humans KW - Hydrophobic and Hydrophilic Interactions KW - Immunoglobulin Variable Region KW - Models, Molecular KW - Molecular Sequence Data KW - Protein Binding KW - Protein Multimerization KW - Protein Structure, Secondary KW - Protein Structure, Tertiary KW - Receptor, erbB-2 KW - Solutions KW - Transition Temperature AB - Single-domain antibodies (sdAbs) derived from human V H are considered to be less soluble and prone to aggregate which makes it difficult to determine the crystal structures. In this study, we isolated and characterized two anti-human epidermal growth factor receptor-2 (HER2) sdAbs, Gr3 and Gr6, from a synthetic human V H phage display library. Size exclusion chromatography and surface plasmon resonance analyses demonstrated that Gr3 is a monomer, but that Gr6 is a strict dimer. To understand this different molecular behavior, we solved the crystal structure of Gr6 to 1.6 Å resolution. The crystal structure revealed that the homodimer assembly of Gr6 closely mimics the V H-V L heterodimer of immunoglobulin variable domains and the dimerization interface is dominated by hydrophobic interactions. © 2012 Baral et al. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 613c082e-b2e3-42a1-b53e-1c73aebc5aa7 ER - TY - JOUR TI - Mathematical modelling of flow and heat/mass transfer during reactive spraying deposition technology (RSDT) process for high temperature fuel cells AU - Hu, G. AU - Neagu, R. AU - Wang, Q. AU - Zhang, Z. AU - Li, G. AU - Zheng, Y. T2 - Engineering Applications of Computational Fluid Mechanics SN - 1994-2060 VL - 6 IS - 1 SP - 134 EP - 143 AB - A three-dimensional mathematical model of flow and heat/mass transfer coupling with chemical reactions for fuel gas and droplet combustion during reactive spraying deposition technology (RSDT) is presented in this paper. The RNG k- ε model is employed in the numerical simulation of turbulent combustion gas flow. The droplet particle is tracked and analyzed in a Lagrangian frame. The heating and vaporization histories of the injected droplet are also calculated during its movement. The three-dimensional distributions of velocity, species concentration and temperature are numerically obtained. The results indicate that the droplet will disappear over a very short distance and the vaporized fuel gas will burn immediately. Both the methods and the results described in this paper will help in the control of the final catalyst particle size and the optimization of the microstructure of the catalyst layer. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 30b5b3cf-21fb-4842-9c60-1fc1c8e33b69 ER - TY - JOUR TI - Specific synthesis of neurostatin and gangliosides O-acetylated in the outer sialic acids using a sialate transferase DO - 10.1371/journal.pone.0049983 AU - Romero-Ramírez, L. AU - García-Álvarez, I. AU - Campos-Olivas, R. AU - Gilbert, M. AU - Goneau, M.-F. AU - Fernández-Mayoralas, A. AU - Nieto-Sampedro, M. T2 - PLoS ONE SN - 1932-6203 VL - 7 IS - 12 SP - e49983 KW - acyltransferase KW - antineoplastic agent KW - cholic acid KW - ganglioside KW - ganglioside GD 1b KW - glycosphingolipid KW - neurostatin KW - sialate transferase KW - sialic acid KW - transferase KW - unclassified drug KW - acetylation KW - antineoplastic activity KW - article KW - concentration (parameters) KW - drug determination KW - drug structure KW - drug synthesis KW - hydrolysis KW - intermethod comparison KW - matrix assisted laser desorption ionization time of flight mass spectrometry KW - molecular interaction KW - molecular weight KW - proton nuclear magnetic resonance KW - Acetylation KW - Acetyltransferases KW - Campylobacter jejuni KW - Carbohydrate Sequence KW - Chromatography, High Pressure Liquid KW - Chromatography, Thin Layer KW - Gangliosides KW - Glycosphingolipids KW - Magnetic Resonance Spectroscopy KW - Molecular Sequence Data KW - Recombinant Proteins KW - Sialic Acids KW - Spectrometry, Mass, Electrospray Ionization KW - Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization KW - Campylobacter jejuni AB - Gangliosides are sialic acid containing glycosphingolipids, commonly found on the outer leaflet of the plasma membrane. O-acetylation of sialic acid hydroxyl groups is one of the most common modifications in gangliosides. Studies on the biological activity of O-acetylated gangliosides have been limited by their scarcity in nature. This comparatively small change in ganglioside structure causes major changes in their physiological properties. When the ganglioside GD1b was O-acetylated in the outer sialic acid, it became the potent inhibitor of astroblast and astrocytoma proliferation called Neurostatin. Although various chemical and enzymatic methods to O-acetylate commercial gangliosides have been described, O-acetylation was nonspecific and produced many side-products that reduced the yield. An enzyme with O-acetyltransferase activity (SOAT) has been previously cloned from the bacteria Campylobacter jejuni. This enzyme catalyzed the acetylation of oligosaccharide-bound sialic acid, with high specificity for terminal alpha-2,8-linked residues. Using this enzyme and commercial gangliosides as starting material, we have specifically O-acetylated the gangliosides' outer sialic acids, to produce the corresponding gangliosides specifically O-acetylated in the sialic acid bound in alpha-2,3 and alpha-2,8 residues. We demonstrate here that O-acetylation occurred specifically in the C-9 position of the sialic acid. In summary, we present a new method of specific O-acetylation of ganglioside sialic acids that permits the large scale preparation of these modified glycosphingolipids, facilitating both, the study of their mechanism of antitumoral action and their use as therapeutic drugs for treating glioblastoma multiform (GBM) patients. © 2012 Romero-Ramírez et al. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1bc4a95f-315e-48e7-89e1-6743f520e4ac ER - TY - JOUR TI - Awaveguide-coupled on-chip single-photon source DO - 10.1103/PhysRevX.2.011014 AU - Laucht, A. AU - Pütz, S. AU - Günthner, T. AU - Hauke, N. AU - Saive, R. AU - Frédérick, S. AU - Bichler, M. AU - Amann, M.-C. AU - Holleitner, A.W. AU - Kaniber, M. AU - Finley, J.J. T2 - Physical Review X SN - 2160-3308 VL - 2 IS - 1 SP - 1 EP - 7 KW - Autocorrelation measurement KW - Coupling efficiency KW - Emission rates KW - GaAs KW - InGaAs quantum dots KW - On chips KW - Optical modes KW - Photonic crystal waveguide KW - Self-assembled KW - Single mode KW - Single photon generation KW - Single-photon source KW - Time-resolved photoluminescence KW - Waveguide mode KW - Confocal microscopy KW - Optical waveguides KW - Waveguides KW - Particle beams AB - We investigate single-photon generation from individual self-assembled InGaAs quantum dots coupled to the guided optical mode of a GaAs photonic crystal waveguide. By performing confocal microscopy measurements on single dots positioned within the waveguide, we locate their positions with a precision better than 0:5 μm. Time-resolved photoluminescence and photon autocorrelation measurements are used to prove the single-photon character of the emission into the propagating waveguide mode. The results obtained demonstrate that such nanostructures can be used to realize an on-chip, highly directed singlephoton source with single-mode spontaneous emission coupling efficiencies in excess of βΓ ~ 85% and the potential to reach maximum emission rates >1 GHz. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5d4f9548-22f3-48a7-8e38-a0de539c3b77 ER - TY - JOUR TI - Robust force controller for industrial robots: Optimal design and real-time implementation on a KUKA robot DO - 10.1109/TCST.2011.2112661 AU - Bigras, P. AU - Lambert, M. AU - Perron, C. T2 - IEEE Transactions on Control Systems Technology SN - 1063-6536 VL - 20 IS - 2 SP - 5725140 SP - 473 EP - 479 KW - Dual iteration algorithm KW - KUKA robot KW - Linear matrix inequality (LMI) KW - Non-linear matrix inequality KW - Optimal design KW - Position response KW - Real-time implementations KW - Robust controllers KW - Robust force KW - Algorithms KW - Controllers KW - Force control KW - Industrial robots KW - Industry KW - Linear matrix inequalities KW - Real time control KW - Stiffness matrix KW - Machine design AB - In this brief, a new formulation is proposed for the design of a robust force controller for industrial robots with closed architecture controller. A recent model, which takes into account the complete kinematics of the system and the position response of the industrial robot controller, allows this formulation. The proposed design is based on a set of nonlinear matrix inequalities, and solved by the dual iteration algorithm. The robust controller is implemented on a KUKA robot. Good results are obtained with the proposed approach. © 2011 IEEE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 271c1e15-4eaf-40d6-9a22-a8ac787c5a51 ER - TY - JOUR TI - VLBI for Gravity Probe B. II. Monitoring of the structure of the reference sources 3C 454.3, B2250+194, and B2252+172 DO - 10.1088/0067-0049/201/1/2 AU - Ransom, R.R. AU - Bartel, N. AU - Bietenholz, M.F. AU - Lebach, D.E. AU - Lederman, J.I. AU - Luca, P. AU - Ratner, M.I. AU - Shapiro, I.I. T2 - Astrophysical Journal, Supplement Series SN - 0067-0049 VL - 201 IS - 1 SP - 2 AB - We used 8.4GHz very long baseline interferometry images obtained at up to 35 epochs between 1997 and 2005 to examine the radio structures of the main reference source, 3C 454.3, and two secondary reference sources, B2250+194 and B2252+172, for the guide star for the NASA/Stanford relativity mission Gravity Probe B (GP-B). For one epoch in 2004 May, we also obtained images at 5.0 and 15.4GHz. The 35 8.4GHz images for quasar 3C 454.3 confirm a complex, evolving, core-jet structure. We identified at each epoch a component, C1, near the easternmost edge of the core region. Simulations of the core region showed that C1 is located, on average, 0.18 ± 0.06mas west of the unresolved "core" identified in 43GHz images. We also identified in 3C 454.3 at 8.4GHz several additional components that moved away from C1 with proper motions ranging in magnitude between 0.9 c and 5 c. The detailed motions of the components exhibit two distinct bends in the jet axis located 3 and 5.5mas west of C1. The spectra between 5.0 and 15.4GHz for the "moving" components are steeper than those for C1. The 8.4GHz images of B2250+194 and B2252+172, in contrast to those of 3C 454.3, reveal compact structures. The spectrum between 5.0 and 15.4GHz for B2250+194 is inverted while that for B2252+172 is flat. Based on its position near the easternmost edge of the 8.4GHz radio structure, close spatial association with the 43GHz core, and relatively flat spectrum, we believe 3C 454.3 component C1 to be the best choice for the ultimate reference point for the GP-B guide star. The compact structures and inverted-to-flat spectra of B2250+194 and B2252+172 make these objects valuable secondary reference sources. © 2012. The American Astronomical Society. All rights reserved.. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 378d55ad-4ff6-4f08-96e1-d4c9f5e14dff ER - TY - JOUR TI - Determination of optimum process conditions for processing AS4/APC-2 thermoplastic composites by automated fiber placement AU - Cai, X. AU - Shadmehri, F. AU - Hojjati, M. AU - Chen, J. AU - Van Hoa, S. T2 - International SAMPE Technical Conference T3 - 2012 SAMPE International Symposium and Exhibition - Emerging Opportunities: Materials and Process Solutions, 21 May 2012 through 24 May 2012, Baltimore, MD SN - 9781934551127 KW - Crystallinities KW - Digital image correlations KW - Fiber placement KW - Interlaminar shear strength KW - Microscopic photos KW - Optimum process conditions KW - Process condition KW - Process parameters KW - Shear tests KW - Thermoplastic composite KW - Differential scanning calorimetry KW - Exhibitions KW - Taguchi methods KW - Thermoplastics KW - Composite materials KW - Assembly KW - Calorimetry KW - Composites KW - Failure KW - Tensile Strength KW - Thermoplastics AB - In this study, thermoplastic composite (AS4/APC-2) rings were fabricated using automated fiber placement technique. To compare the quality of the rings under different process conditions, differential scanning calorimetry (DSC) test was conducted to investigate the crystallinity level in the samples. Short-beam shear test was performed to demine the interlaminar shear strength. Digital Image Correlation (DIC) technique was used to measure ultimate through-the-thickness strain. Microscopic photos were used to determine the failure mode. Based on the short-beam strength results, Taguchi method was employed to identify the significance of each process parameters and to obtain the optimum process conditions. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 29e3178a-c183-4b42-8478-cdc03bb231e1 ER - TY - JOUR TI - Conformational modes in biomolecules: Dynamics and approximate invariance DO - 10.1103/PhysRevE.85.020901 AU - Potapov, A. AU - Stepanova, M. T2 - Physical Review E - Statistical, Nonlinear, and Soft Matter Physics SN - 1539-3755 VL - 85 IS - 2 SP - 20901 KW - Biomolecular dynamics KW - Coarse-grained structure KW - Conformational change KW - Conformational dynamics KW - Dimensionality reduction KW - Dynamical properties KW - Human prion protein KW - Invariant properties KW - Molecular dynamics simulations KW - Molecular dynamics trajectories KW - Multi-scale approaches KW - Perturbation theory KW - Physical mechanism KW - Soft matter KW - Subnanosecond KW - Theoretical framework KW - Time-dependent KW - Biomolecules KW - Molecular dynamics KW - Statistical mechanics KW - Dynamics AB - Understanding the physical mechanisms behind the folding and conformational dynamics of biomolecules is one of the major unsolved challenges of soft matter theory. In this contribution, a theoretical framework for biomolecular dynamics is introduced, employing selected aspects of statistical mechanics, dimensionality reduction, the perturbation theory, and the theory of matrices. Biomolecular dynamics is represented by time-dependent orthogonal conformational modes, the dynamics of the modes is investigated, and invariant properties that persist are identified. As an example, the dynamics of a human prion protein is considered. The theory provides a rigorous background for assessing the stable dynamical properties of biomolecules, such as their coarse-grained structure, through a multiscale approach using short subnanosecond segments of molecular dynamics trajectories. Furthermore, the paper offers a theoretical platform for models of conformational changes in macromolecules, which may allow complementing molecular dynamics simulations. ©2012 American Physical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d23b9364-1662-45b9-8b52-89ed3009a399 ER - TY - JOUR TI - Structural bonding of the next generation large canadarm (NGLC) ground test bed AU - Djokic, D. AU - Krimbalis, P.P. AU - Hay, G. AU - Cole, R. AU - Rogers, J. AU - Brunet, S. T2 - International SAMPE Technical Conference T3 - SAMPE Tech 2012 Conference and Exhibition: Navigating the Global Landscape for the New Composites, 22 October 2012 through 25 October 2012, North Charleston, SC SN - 9781934551134 KW - Bondline thickness KW - Dimensional tolerance KW - Finite element models KW - Manipulator systems KW - Mechanical fastener KW - Progressive damage KW - Telescoping segments KW - Torsional stiffness KW - Adhesive joints KW - Aluminum KW - Cargo handling KW - Continuum mechanics KW - Equipment testing KW - Exhibitions KW - Finite element method KW - Optimization KW - Robotic arms KW - Stiffness KW - Translation (languages) KW - Reduction AB - The Next Generation Large Canadarm (NGLC) ground test bed is constrained by the physical stowage volume available on future exploration vehicles. NGLC demonstrates a reduction in the launch package of a large manipulator system while maintaining reach capability through deployment and retraction. NGLC is comprised of two telescoping segments, connected by three pitch joints. The segments consist of an inner and outer boom with a lock mechanism for either position. A rail network allows relative translation of the booms. NGLC bending and torsional stiffness requirements were met through the use of composite materials and adhesive bonding. Each boom features a centre composite section bonded to two aluminum sections using a stepped-lap joint. The elimination of mechanical fasteners maximized NGLC stiffness through a reduction of the clearance required between the telescoping assemblies and an increase of the inner segment diameter. Progressive damage finite element (FE) models optimized the lay-up and predicted positive margins of safety for combined bending and torsion load cases. Continuum mechanics analysis of the bonded joint was used to predict adhesive and adherend stresses due to the applied loads. A modular bonding apparatus with constrained relative adherend translation accommodated customized bonding processes for each operation. Steel rail segments were simultaneously bonded to the composite section inner surfaces, while the composite and aluminum sections were sequentially bonded. The joint and the bonding processes were optimized for bondline thickness control and minimum void entrapment. Key challenges included maintaining dimensional tolerances over the large structure, excess adhesive management and fouling of inaccessible critical surfaces. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 95c3a7c2-31f3-4ac3-bc6a-3147a3970a67 ER - TY - JOUR TI - State-related changes in MEG functional connectivity reveal the task-positive sensorimotor network DO - 10.1371/journal.pone.0048682 AU - Bardouille, T. AU - Boe, S. T2 - PLoS ONE SN - 1932-6203 VL - 7 IS - 10 SP - e48682 KW - adult KW - anatomical variation KW - article KW - beta rhythm KW - brain function KW - electroencephalogram KW - female KW - frontal eye field KW - functional assessment KW - gamma rhythm KW - human KW - human experiment KW - image analysis KW - image display KW - magnetoencephalography KW - male KW - motor performance KW - neuroimaging KW - normal human KW - prefrontal cortex KW - rest KW - sensorimotor function KW - task performance KW - visual feedback KW - Adult KW - Brain KW - Brain Mapping KW - Cues KW - Female KW - Humans KW - Magnetoencephalography KW - Male KW - Nerve Net KW - Psychomotor Performance KW - Reproducibility of Results KW - Rest KW - Visual Perception KW - Young Adult AB - Functional connectivity measures applied to magnetoencephalography (MEG) data have the capacity to elucidate neuronal networks. However, the task-related modulation of these measures is essential to identifying the functional relevance of the identified network. In this study, we provide evidence for the efficacy of measuring "state-related" (i.e., task vs. rest) changes in MEG functional connectivity for revealing a sensorimotor network. We investigate changes in functional connectivity, measured as cortico-cortical coherence (CCC), between rest blocks and the performance of a visually directed motor task in a healthy cohort. Task-positive changes in CCC were interpreted in the context of any concomitant modulations in spectral power. Task-related increases in whole-head CCC relative to the resting state were identified between areas established as part of the sensorimotor network as well as frontal eye fields and prefrontal cortices, predominantly in the beta and gamma frequency bands. This study provides evidence for the use of MEG to identify task-specific functionally connected sensorimotor networks in a non-invasive, patient friendly manner. © 2012 Bardouille, Boe. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 404ba69f-1e3f-4f3d-87f7-84b2ca9a3ba5 ER - TY - JOUR TI - Influence of speciation on the response from selenium to UV-photochemical vapor generation DO - 10.2116/analsci.28.807 AU - Suzuki, Toshihiro AU - Sturgeon, Ralph E. AU - Zheng, Chengbin AU - Hioki, Akiharu AU - Nakazato, Tetsuya AU - Tao, Hiroaki T2 - Analytical Sciences SN - 0910-6340 VL - 28 IS - 8 SP - 807 EP - 811 AB - By exposure to appropriate UV intensities, rapid and quantitative oxidation/reduction of inorganic selenite, selenate and several organoselenium compounds representative of those of biochemical/metabolic interest, including selenomethionine, selenobetaine, L-selenocystine, selenomethylselenocysteine, γ-glutamyl-seleno-methylselenocysteine and selenocystamine, is achieved. In the presence of acetic acid, quantitative conversion to volatile SeH₂ and SeCO occurs using a flow-through system comprising a highly efficient 40 W UV lamp for oxidation in tandem with a lower power 8 W UV photocatalytic reactor utilizing a thin-film coating of titania. The volatile reduced species are detected by atomic absorption spectrometry using a heated quartz tube atomizer. Direct photochemical conversion of selenite, selenomethionine, L-selenocystine, γ-glutamyl-Se-methylselenocysteine and selenocystamine occurs in the presence of 5% acetic acid, following exposure to an 8 W UV field, to yield volatile detectable species, whereas selenobetaine and selenate are unresponsive unless the latter is first subjected to oxidation by exposure to a highly efficient 40 W UV lamp and the selenate reduced in the presence of titania. © The Japan Society for Analytical Chemistry. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 286b3dad-577d-43e0-8941-753abf0e21a5 ER - TY - JOUR TI - Experimental modeling of extreme hydrodynamic forces on structural models DO - 10.1260/2041-4196.3.4.477 AU - Al-Faesly, Taofiq AU - Palermo, Dan AU - Nistor, Ioan AU - Cornett, Andrew T2 - International Journal of Protective Structures SN - 2041-4196 VL - 3 IS - 4 SP - 477 EP - 506 KW - Cross-sectional shape KW - Displacement-time history KW - Experimental modeling KW - Experimental program KW - Experimental testing KW - Federal Emergency Management Agency KW - FEMA P646 KW - Hydrodynamic forces KW - Flow velocity KW - Hydrodynamics KW - Model structures KW - Structural design KW - Tsunamis KW - Video recording KW - Walls (structural partitions) KW - Shear flow AB - This paper presents the results of a comprehensive experimental program focused on the impact of extreme hydrodynamic forces on structural models generated by a turbulent hydraulic bore. The parameters investigated include: (1) bore depth-time history; (2) initial flume-bed conditions (dry bed versus wet); and (3) damping effect of mitigation walls on the hydrodynamic forces. At impact, the maximum inundation (bore) depths varied between 250 mm and 450 mm and the bore front velocity ranged from 2.6 m/s to 5.0 m/s. High-speed video recordings of the bore-structural model interaction were captured simultaneously with the base shear force-, pressure-, base overturning moment-, and top lateral displacement-time histories experienced by the structural models. Three force components were identified in the bore-induced force-time histories: impulsive, run-up (transient hydrodynamic force), and quasi-steady hydrodynamic. The impulsive or run-up force was the maximum force component experienced by the structural models under initial dry-bed flume conditions; while for the initial wet-bed flume condition, the run-up force component was the maximum force. The effect of 100 mm and 150 mm low-height mitigation walls inclined at angles of 45° or 90°, which were installed at distances of 305 mm or 915 mm upstream from the structural model, was also investigated. The angle of inclination of the mitigation walls, its location relative to the structural model, and its cross-sectional shape all influence the base shear force- and base overturning moment-time histories. The base shear forces in the direction of the flow measured during experimental testing were greater than those estimated using the Federal Emergency Management Agency (FEMA) document P646, while the Structural Design Method of Buildings for Tsunami Resistance (SMBTR) overestimated the base shear forces. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b8f972db-66c1-43d4-89dd-04d7276df948 ER - TY - JOUR TI - Micromachined edge illuminated optically transparent automotive light guide panels DO - 10.1117/12.908202 AU - Ronny, R.A. AU - Knopf, G.K. AU - Bordatchev, E. AU - Tauhiduzzaman, M. AU - Nikumb, S. T2 - Progress in Biomedical Optics and Imaging - Proceedings of SPIE T3 - Micromachining and Microfabrication Process Technology XVII, 24 January 2012 through 26 January 2012, San Francisco, CA SN - 1605-7422 SN - 9780819488916 VL - 8248 SP - 824806 KW - Active regions KW - Automotive applications KW - Automotive light panels KW - Automotive lighting KW - Edge lighting KW - Fringe-effects KW - Light guide panels KW - Lighting panels KW - Luminance uniformity KW - Micro milling KW - Micro-optical elements KW - Micromachined KW - New design KW - Optical light KW - Optical simulation KW - Spatial distribution patterns KW - Test samples KW - Transparent plastics KW - Variable parameters KW - Composite micromechanics KW - Diffractive optics KW - Lighting KW - Liquid crystal displays KW - Microanalysis KW - Microfabrication KW - Microoptics KW - Milling (machining) KW - Optical fibers KW - Micromachining AB - Edge-lit backlighting has been used extensively for a variety of small and medium-sized liquid crystal displays (LCDs). The shape, density and spatial distribution pattern of the micro-optical elements imprinted on the surface of the flat light-guide panel (LGP) are often "optimized" to improve the overall brightness and luminance uniformity. A similar concept can be used to develop interior convenience lighting panels and exterior tail lamps for automotive applications. However, costly diffusive sheeting and brightness enhancement films are not be considered for these applications because absolute luminance uniformity and the minimization of Moiré fringe effects are not significant factors in assessing quality of automotive lighting. A new design concept that involves micromilling cylindrical micro-optical elements on optically transparent plastic substrates is described in this paper. The variable parameter that controls illumination over the active regions of the panel is the depth of the individual cylindrical micro-optical elements. LightToolsTM is the optical simulation tool used to explore how changing the micro-optical element depth can alter the local and global luminance. Numerical simulation and microfabrication experiments are performed on several (100mmx100mmx6mm) polymethylmethacrylate (PMMA) test samples in order to verify the illumination behavior. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 570a6190-a754-43f9-aea5-bac643e75ec1 ER - TY - JOUR TI - The genome of flax (Linum usitatissimum) assembled de novo from short shotgun sequence reads DO - 10.1111/j.1365-313X.2012.05093.x AU - Wang, Z. AU - Hobson, N. AU - Galindo, L. AU - Zhu, S. AU - Shi, D. AU - McDill, J. AU - Yang, L. AU - Hawkins, S. AU - Neutelings, G. AU - Datla, R. AU - Lambert, G. AU - Galbraith, D.W. AU - Grassa, C.J. AU - Geraldes, A. AU - Cronk, Q.C. AU - Cullis, C. AU - Dash, P.K. AU - Kumar, P.A. AU - Cloutier, S. AU - Sharpe, A.G. AU - Wong, G.K.-S. AU - Wang, J. AU - Deyholos, M.K. T2 - Plant Journal SN - 0960-7412 VL - 72 IS - 3 SP - 461 EP - 473 KW - DNA Sequencing KW - Illumina KW - Industrial crops KW - Malpighiales KW - Whole-genome shotgun KW - Crops KW - DNA sequences KW - Flax KW - Linen KW - Proteins KW - Yarn KW - Genes KW - plant DNA KW - article KW - bacterial artificial chromosome KW - chemistry KW - chromosome map KW - contig mapping KW - DNA sequence KW - expressed sequence tag KW - flax KW - gene library KW - genetics KW - high throughput sequencing KW - methodology KW - molecular genetics KW - nucleotide sequence KW - plant genome KW - protein tertiary structure KW - Base Sequence KW - Chromosome Mapping KW - Chromosomes, Artificial, Bacterial KW - Contig Mapping KW - DNA, Plant KW - Expressed Sequence Tags KW - Flax KW - Gene Library KW - Genome, Plant KW - High-Throughput Nucleotide Sequencing KW - Molecular Sequence Annotation KW - Molecular Sequence Data KW - Protein Structure, Tertiary KW - Sequence Analysis, DNA KW - Arabidopsis thaliana KW - Linum usitatissimum KW - Malpighiales AB - Flax (Linum usitatissimum) is an ancient crop that is widely cultivated as a source of fiber, oil and medicinally relevant compounds. To accelerate crop improvement, we performed whole-genome shotgun sequencing of the nuclear genome of flax. Seven paired-end libraries ranging in size from 300 bp to 10 kb were sequenced using an Illumina genome analyzer. A de novo assembly, comprised exclusively of deep-coverage (approximately 94× raw, approximately 69× filtered) short-sequence reads (44-100 bp), produced a set of scaffolds with N50 = 694 kb, including contigs with N50 = 20.1 kb. The contig assembly contained 302 Mb of non-redundant sequence representing an estimated 81% genome coverage. Up to 96% of published flax ESTs aligned to the whole-genome shotgun scaffolds. However, comparisons with independently sequenced BACs and fosmids showed some mis-assembly of regions at the genome scale. A total of 43 384 protein-coding genes were predicted in the whole-genome shotgun assembly, and up to 93% of published flax ESTs, and 86% of A. thaliana genes aligned to these predicted genes, indicating excellent coverage and accuracy at the gene level. Analysis of the synonymous substitution rates (Ks) observed within duplicate gene pairs was consistent with a recent (5-9 MYA) whole-genome duplication in flax. Within the predicted proteome, we observed enrichment of many conserved domains (Pfam-A) that may contribute to the unique properties of this crop, including agglutinin proteins. Together these results show that de novo assembly, based solely on whole-genome shotgun short-sequence reads, is an efficient means of obtaining nearly complete genome sequence information for some plant species. © 2012 Blackwell Publishing Ltd. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5b86f63f-c054-418f-a0c1-6b87778682be ER - TY - CHAP TI - Magnetic Resonance Technology DO - 10.1002/9781118271933.ch5 AU - Tomanek, B. AU - Sharp, J.C. T2 - Biomedical Imaging: Principles and Applications SN - 9780470648476 SP - 131 EP - 179 DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 54710d8b-a357-42ea-8096-9b1ad1604d42 ER - TY - JOUR TI - Star formation in the outer disk of spiral galaxies DO - 10.1088/0004-637X/757/1/64 AU - Barnes, K.L. AU - Van Zee, L. AU - Côté, S. AU - Schade, D. T2 - The Astrophysical Journal SN - 0004-637X VL - 757 IS - 1 SP - 64 AB - We combine new deep and wide field of view Hα imaging of a sample of eight nearby (d 17Mpc) spiral galaxies with new and archival H I and CO imaging to study the star formation and the star formation regulation in the outer disk. We find that, in agreement with previous studies, star formation in the outer disk has low covering fractions, and star formation is typically organized into spiral arms. The star formation in the outer disk is at extremely low levels, with typical star formation rate surface densities of ∼10 -5 to 10 -6 M Oyr -1kpc -2. We find that the ratio of the radial extent of detected H II regions to the radius of the H I disk is typically ≳85%. This implies that in order to further our understanding of the implications of extended star formation, we must further our understanding of the formation of extended H I disks. We measure the gravitational stability of the gas disk, and find that the outer gaseous disk is typically a factor of ∼2times more stable than the inner star-forming disk. We measure the surface density of outer disk H I arms, and find that the disk is closer to gravitational instability along these arms. Therefore, it seems that spiral arms are a necessary, but not sufficient, requirement for star formation in the outer disk. We use an estimation of the flaring of the outer gas disk to illustrate the effect of flaring on the Schmidt power-law index; we find that including flaring increases the agreement between the power-law indices of the inner and outer disks. © 2012. The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b42028d0-9776-46c8-83bc-26fab4b35e2b ER - TY - JOUR TI - Quantum random bit generation by stimulated Raman scattering AU - Bustard, P.J. AU - Moffatt, D. AU - Lausten, R. AU - Wu, G. AU - Walmsley, I.A. AU - Sussman, B.J. T2 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012 T3 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012, 6 May 2012 through 11 May 2012, San Jose, CA SN - 9781467318396 SP - 6326885 KW - Random number generators KW - Vacuum fluctuations KW - Zero-point KW - Lasers KW - Random number generation KW - Stimulated Raman scattering AB - We introduce a quantum random number generator based on the phase measurement of Stokes light generated by amplification of zero-point vacuum fluctuations using stimulated Raman scattering in bulk diamond. © 2012 OSA. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0f1204e0-dc7d-4d97-a10e-94aac1b7869a ER - TY - JOUR TI - The spectroscopic orbits OF HD 23052 and HD 90512 AU - Scarfe, C.D. AU - Griffin, R.F. T2 - Revista Mexicana de Astronomia y Astrofisica SN - 0185-1101 VL - 48 IS - 2 SP - 257 EP - 265 AB - We present radial-velocity observations from DAO and Cambridge, from which we derive orbital elements. HD 23052 is a G-type main-sequence object which has been regarded as a solar analogue, in an orbit of period nearly three years. HD 90512 is a G-type giant in a nearly circular orbit with a period just over 100 days. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 46b4d473-3040-47cb-bfcc-f154dadf6c4a ER - TY - JOUR TI - Rapid and simple preparation of a reagentless glucose electrochemical biosensor DO - 10.1039/c2an35128e AU - Zheng, D. AU - Vashist, S.K. AU - Al-Rubeaan, K. AU - Luong, J.H.T. AU - Sheu, F.-S. T2 - Analyst SN - 0003-2654 VL - 137 IS - 16 SP - 3800 EP - 3805 KW - carbon KW - glass KW - glucose KW - glucose oxidase KW - immobilized enzyme KW - article KW - Aspergillus niger KW - chemistry KW - electrochemistry KW - electrode KW - enzymology KW - genetic procedures KW - metabolism KW - methodology KW - time KW - Aspergillus niger KW - Biosensing Techniques KW - Carbon KW - Electrochemistry KW - Electrodes KW - Enzymes, Immobilized KW - Glass KW - Glucose KW - Glucose Oxidase KW - Time Factors AB - A rapid and simple procedure was developed for the preparation of a highly stable and leach-proof glucose oxidase (GOx)-bound glassy carbon electrode (GCE). Crosslinked GOx via glutaraldehyde was drop-cast on a KOH-pretreated GCE followed by drop-casting of 3-aminopropyltriethoxysilane (APTES) to form a stable bioactive layer. At -0.45 V, the biosensor exhibited a wide dynamic detection range of 0.5-48 mM for commercial glucose and 1.3-28.2 mM for Sugar-Chex blood glucose linearity standards. Several endogenous electroactive substances and drug metabolites commonly found in blood were tested and provoked no signal response. To our knowledge, the developed procedure is the most rapid method for preparing a glucose biosensor. The biosensor suffered no biofouling after 7 days of immersion in Sugar-Chex blood glucose. With excellent production reproducibility, GOx-bound electrodes stored dry at room temperature retained their initial activity after several weeks. © 2012 The Royal Society of Chemistry. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 749bbafd-4f02-4b1d-924d-68487e96c7f1 ER - TY - JOUR TI - The velocity dispersion and mass function of the outer halo globular cluster Palomar 4 DO - 10.1111/j.1365-2966.2012.21105.x AU - Frank, M.J. AU - Hilker, M. AU - Baumgardt, H. AU - Côté, P. AU - Grebel, E.K. AU - Haghi, H. AU - Küpper, A.H.W. AU - Djorgovski, S.G. T2 - Monthly Notices of the Royal Astronomical Society SN - 0035-8711 VL - 423 IS - 3 SP - 2917 EP - 2932 AB - We obtained precise line-of-sight radial velocities of 23 member stars of the remote halo globular cluster Palomar4 (Pal4) using the High Resolution Echelle Spectrograph at the Keck I telescope. We also measured the mass function of the cluster down to a limiting magnitude of V~ 28mag using archival Hubble Space Telescope/Wide Field Planetary Camera 2 (WFPC2) imaging. We derived the cluster's surface brightness profile based on the WFPC2 data and on broad-band imaging with the Low Resolution Imaging Spectrometer at the Keck II telescope. We find a mean cluster velocity of 72.55 ± 0.22kms -1 and a velocity dispersion of 0.87 ± 0.18kms -1. The global mass function of the cluster, the mass range 0.55 ≤M≤ 0.85M ⊙, is shallower than a Kroupa mass function and the cluster is significantly depleted low-mass stars its centre compared to its outskirts. Since the relaxation time of Pal4 is of the order of a Hubble time, this points to primordial mass segregation this cluster. Extrapolating the measured mass function towards lower mass stars and including the contribution of compact remnants, we derive a total cluster mass of 29800M ⊙. For this mass, the measured velocity dispersion is consistent with the expectations of Newtonian dynamics and below the prediction of modified Newtonian dynamics (MOND). Pal4 adds to the growing body of evidence that the dynamics of star clusters the outer Galactic halo can hardly be explained by MOND. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9e27d02c-6fa3-41ab-90ce-d29baae59329 ER - TY - JOUR TI - Spatial control of electronic wave packets with attosecond precision DO - 10.1088/1742-6596/388/3/032069 AU - Zhang, Li AU - Xie, Xinhua AU - Roither, Stefan AU - Kartashov, Daniil AU - Schöffler, Markus AU - Shafir, Dror AU - Corkum, Paul AU - Baltuka, Andrius AU - Staudte, André AU - Kitzler, Markus T2 - Journal of Physics: Conference Series T3 - 27th International Conference on Photonic, Electronic and Atomic Collisions, ICPEAC 2011, July 27 - August 2, 2011, Belfast, UK SN - 1742-6588 VL - 388 IS - 3 SP - 32069 KW - Attoseconds KW - Electronic wave packets KW - Spatial control KW - Two-color laser fields KW - Atoms KW - Wave packets AB - Atomic single- and double- ionization using orthogonally polarized two-color laser fields was investigated via COLTRILMS technique. We prove that the electronic wave packets can be spatially controlled with attosecond precision. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 065b0037-c8df-4b2e-8673-b0f95d8e3ccf ER - TY - JOUR TI - Magnetic Milky Way DO - 10.1051/eas/1256010 AU - Vallée, J.P. T2 - EAS Publications Series T3 - The Role of the Disk-Halo Interaction in Galaxy Evolution: Outflows vs. Infall?, 18 August 2008 through 22 August 2008, Espinho SN - 1633-4760 SN - 9782759807871 VL - 56 SP - 81 EP - 86 KW - Magnetic field line KW - Milky ways KW - Spiral arms KW - Publishing KW - Galaxies AB - Spiral arm shapes, locations, and velocities can be well determined, when model pitfalls are avoided (Vallée 2008a). Similarly, circularly orbiting gas and magnetic field lines can cross the spiral arms, when observational pitfalls are avoided (Vallée 2008b). © EAS, EDP Sciences 2012. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 017d7a25-aff1-440f-8c78-5d739bb3d061 ER - TY - JOUR TI - The spectral energy distributions of white dwarfs in 47 Tucanae: The distance to the cluster DO - 10.1088/0004-6256/143/2/50 AU - Woodley, K.A. AU - Goldsbury, R. AU - Kalirai, J.S. AU - Richer, H.B. AU - Tremblay, P.-E. AU - Anderson, J. AU - Bergeron, P. AU - Dotter, A. AU - Esteves, L. AU - Fahlman, G.G. AU - Hansen, B.M.S. AU - Heyl, J. AU - Hurley, J. AU - Rich, R.M. AU - Shara, M.M. AU - Stetson, P.B. T2 - Astronomical Journal SN - 0004-6256 VL - 143 IS - 2 SP - 50 AB - We present a new distance determination to the Galactic globular cluster 47 Tucanae by fitting the spectral energy distributions of its white dwarfs (WDs) to pure hydrogen atmosphere WD models. Our photometric data set is obtained from a 121-orbit Hubble Space Telescope program using the Wide Field Camera 3 UVIS/IR channels, capturing F390W, F606W, F110W, and F160W images. These images cover more than 60 arcmin 2 and extend over a radial range of 5-13.7 arcmin (6.5-17.9pc) within the globular cluster. Using a likelihood analysis, we obtain a best-fitting unreddened distance modulus of (m - M) o = 13.36 0.02 0.06 corresponding to a distance of 4.69 0.04 0.13kpc, where the first error is random and the second is systematic. We also search the WD photometry for infrared excess in the F160W filter, indicative of low-mass companions, and find no convincing cases within our sample. © 2012. The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4b15250b-6884-40ef-aff1-26422f1a422e ER - TY - JOUR TI - Woofer-tweeter temporal correction split in atmospheric adaptive optics DO - 10.1364/OL.37.003132 AU - Correia, C. AU - Véran, J.-P. T2 - Optics Letters SN - 0146-9592 VL - 37 IS - 15 SP - 3132 EP - 3134 KW - Ad hoc approach KW - Correction performance KW - First-order KW - High bandwidth KW - Linear Quadratic Gaussian controllers KW - Low-bandwidth KW - Low-pass KW - LQG controller KW - Optics application KW - Optimal strategies KW - Residual phase KW - Temporal characteristics KW - Temporal filters KW - Thirty Meter Telescope KW - Tilt correction KW - Wavefront corrector KW - Low pass filters KW - Optimal systems KW - Optimization KW - Vision aids KW - Loudspeakers AB - Many adaptive optics applications require wavefront correctors with a high stroke, and at a high bandwidth. Often, these two requirements cannot be met by a single wavefront corrector, and, instead, the combination of a lowbandwidth, high-stroke woofer and a high-bandwidth low-stroke tweeter is used in a so-called woofer-tweeter architecture. The optimal (minimum residual phase variance) way to split the correction between the woofer and the tweeter in the context of a linear-quadratic-Gaussian (LQG) controller has been addressed previously. However, the necessity to fold the temporal characteristics of the woofer and tweeter into the LQG controller significantly increases its complexity. In this Letter, this optimal strategy is compared to a simpler, ad hoc approach, which consists in optimizing the LQG controller as if it were controlling a high-bandwidth, high-stroke corrector and splitting the correction using first-order high- and low-pass temporal filters. In the case of tilt correction for NFIRAOS on the Thirty Meter Telescope, it is found that the ad hoc approach, which is already used or planned for several systems, holds the same overall correction performance compared to the optimal strategy. © 2012 Optical Society of America. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b4796752-499e-4c45-b360-e0a37af0bd32 ER - TY - JOUR TI - Weak lensing measurement of galaxy clusters in the CFHTLS-wide survey DO - 10.1088/0004-637X/748/1/56 AU - Shan, H. AU - Kneib, J.-P. AU - Tao, C. AU - Fan, Z. AU - Jauzac, M. AU - Limousin, M. AU - Massey, R. AU - Rhodes, J. AU - Thanjavur, K. AU - McCracken, H.J. T2 - The Astrophysical Journal SN - 0004-637X VL - 748 IS - 1 SP - 56 AB - We present the first weak gravitational lensing analysis of the completed Canada-France-Hawaii Telescope Legacy Survey (CFHTLS). We study the 64 deg 2 W1 field, the largest of the CFHTLS-Wide survey fields, and present the largest contiguous weak lensing convergence "mass map" yet made. 2.66 million galaxy shapes are measured, using the Kaiser Squires and Broadhurst Method (KSB) pipeline verified against high-resolution Hubble Space Telescope imaging that covers part of the CFHTLS. Our i′-band measurements are also consistent with an analysis of independent r′-band imaging. The reconstructed lensing convergence map contains 301 peaks with signal-to-noise ratio ν > 3.5, consistent with predictions of a ΛCDM model. Of these peaks, 126 lie within 30 of a brightest central galaxy identified from multicolor optical imaging in an independent, red sequence survey. We also identify seven counterparts for massive clusters previously seen in X-ray emission within 6 deg 2 XMM-LSS survey. With photometric redshift estimates for the source galaxies, we use a tomographic lensing method to fit the redshift and mass of each convergence peak. Matching these to the optical observations, we confirm 85 groups/clusters with χ 2 reduced < 3.0, at a mean redshift 〈z c 〉 = 0.36 and velocity dispersion 〈σ c〉 = 658.8 km s -1. Future surveys, such as DES, LSST, KDUST, and EUCLID, will be able to apply these techniques to map clusters in much larger volumes and thus tightly constrain cosmological models. © 2012 The American Astronomical Society. All rights reserved. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f3986d26-652e-4ad3-ac7a-8941cab213eb ER - TY - JOUR TI - V881 Persei: a spotted, detached eclipsing binary AU - Nelson, R. H. T2 - Information Bulletin on Variable Stars SN - 0374-0676 IS - 6017 DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d9f0f575-e648-4831-9170-9d88548e9a96 ER - TY - JOUR TI - Performance of the vapor fed direct alcohol phosphoric acid fuel cell DO - 10.1149/2.087205jes AU - Fan, S. AU - Wilkinson, D.P. AU - Wang, H. T2 - Journal of the Electrochemical Society SN - 0013-4651 VL - 159 IS - 5 SP - B570 EP - B577 KW - Cell performance KW - CO poisoning KW - Comprehensive studies KW - Conventional polymers KW - Electrode assemblies KW - Gas diffusion layers KW - Higher temperatures KW - Microporous layers KW - Nafion membrane KW - Operating condition KW - Performance effect KW - Performance improvements KW - Stream pressure KW - Structure improvement KW - Vapor composition KW - Electrolytes KW - Ethanol KW - Ethanol fuels KW - Methanol KW - Methanol fuels KW - Phosphoric acid KW - Phosphoric acid fuel cells (PAFC) KW - Platinum KW - Proton exchange membrane fuel cells (PEMFC) KW - Silicon carbide KW - Vapors AB - Due to improved kinetics and reduced CO poisoning effects, higher temperature alcohol fuel cells have been shown to have higher activity and increased performance output when compared to lower temperature alcohol fuel cells. In this work, the Direct Alcohol Phosphoric Acid Fuel Cell (DAPAFC) with methanol and ethanol as reactant fuels, and Pt and PtRu as catalysts is studied. The electrolyteseparator consists of Phosphoric Acid in a Silicon Carbide (SiC) matrix and replaces conventional polymer electrolyte or PBI membranes. Comprehensive studies are conducted to demonstrate the performance effects of the Gas Diffusion Layer (GDL), Micro-porous Layer (MPL) and such parameters as the stream pressures, higher temperature operation (120-180°C), and the thickness of the SiC separator, etc. Results show that at the same operating conditions, the cell performance is comparable to that of a vapour fed Nafion membrane based fuel cell. Structure improvement of the Phosphoric Acid Electrode Assembly (PAEA) and reactant vapor composition can significantly improve durability. This type of fuel cell demonstrates performance improvement and stability in a higher temperature range than is possible with the conventional PEMFC. © 2012 The Electrochemical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 69655766-f31b-43f2-80b8-b3e324ad189d ER - TY - JOUR TI - Wing-in-ground effect oscillating foil turbine from concept to innovation DO - 10.2316/P.2012.768-022 AU - Liu, P. T2 - Proceedings of the IASTED Asian Conference on Power and Energy Systems, AsiaPES 2012 T3 - 5th IASTED Asian Conference on Power and Energy Systems, AsiaPES 2012, 2 April 2012 through 4 April 2012, Phuket SN - 9780889869103 SP - 413 EP - 419 KW - Energy research KW - Horizontal axis KW - National Research Council KW - Ocean technology KW - Oscillating foils KW - Panel methods KW - Renewable energy technologies KW - Research and development KW - Testing facility KW - Tool development KW - Wing in ground effect KW - Conceptual design KW - Innovation KW - Research KW - Turbines AB - This paper presents recent turbine research and development work on renewable energy technology development and innovation at the Institute for Ocean Technology, National Research Council Canada. The advantages of the oscillating foil turbines as opposed to horizontal axis turbines are identified and discussed. A wing-in-ground effect (WIG) application for oscillating turbine is introduced and the systematic development of a novel WIG oscillating foil turbine is briefly presented with conceptual design example. In-house simulation tool development, numerical and experimental capability development and testing facilities for turbine energy research are also briefly introduced. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e8e42264-7026-44d6-8bff-ac5004ec5c47 ER - TY - JOUR TI - Morphological zones in micro injection molding of poly(oxymethylene) AU - El Otmani, R. AU - Kamal, M.R. AU - Derdouri, A. T2 - Annual Technical Conference - ANTEC, Conference Proceedings T3 - 70th Annual Technical Conference of the Society of Plastics Engineers 2012, ANTEC 2012, 2 April 2012 through 4 April 2012, Orlando, FL SN - 9781622760831 VL - 3 SP - 1858 EP - 1862 KW - Battenfeld KW - Micro molding KW - Micro-injection molding KW - Microstr8ucture KW - Poly(oxymethylene) KW - Shish-kebabs KW - Skin layer KW - Skin-core KW - Transverse planes KW - Acetal resins KW - Morphology KW - Plastic products KW - Injection molding AB - A Battenfeld System 50 micro injection molding machine was used to produce micro moldings of polyoxymethylene (POM), using a stepwise reduced thickness (0.8 mm, 0.45 mm, 0.2 mm) mold. Polarized light microscopy (PLM) was employed to investigate the morphology of the POM micro moldings. Morphology was examined in both the flow and transverse planes. A variety of morphological zones (oriented skin, shish kebab, cylindrulite, twisted lamellae, oblate, spherulite, etc.) are obtained, depending on the location. The morphology depends strongly on the thickness of the molding and thickness changes. The oriented skin layer tends to diminish away from the gate and near the vent end. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 92ae4580-c1f6-4787-a922-d4d0ae6a318e ER - TY - JOUR TI - Simulations of airfoil limit-cycle oscillations at transitional Reynolds numbers AU - Yuan, W. AU - Poirel, D. AU - Wang, B. AU - Khalid, M. T2 - 50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition T3 - 50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, 9 January 2012 through 12 January 2012, Nashville, TN SP - AIAA 2012-0041 KW - Aeroelastic oscillations KW - Boundary-layer separation KW - Incompressible CFD KW - Limit cycle oscillations KW - Low Reynolds number KW - Low-amplitude KW - Static conditions KW - Structural response KW - Two-degree-of-freedom KW - Aeroelasticity KW - Aerospace engineering KW - Computer simulation KW - Exhibitions KW - Reynolds number KW - Airfoils AB - Structural response models addressing one-degree-of-freedom (1DOF) and two-degree-of-freedom (2DOF) aeroelastic oscillations were coupled with an in-house incompressible CFD code to perform large-eddy-based simulations (LES) for flows past rigid airfoils in free-to-rotate and free-to-rotate-and-heave conditions at low Reynolds numbers. As observed in experiments, the numerical simulations confirmed the presence of the self-sustained low-amplitude limit-cycle oscillations (LCOs) of the airfoils. It is understood that this behavior in the transitional Reynolds number regime results from the unsteadiness of the laminar boundary layer separation and its delayed recovery when compared to the corresponding static conditions. © 2012 by NRC and RMC. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9e2a706c-d93c-4328-ad82-8b1ca46f6188 ER - TY - CHAP TI - Optofluidic Techniques for the Manipulation of Micro Particles: Principles and Applications to Bioanalyses DO - 10.1002/9781118310212.ch3 AU - Guo, H. AU - Xiao, G. AU - Yao, J. T2 - Photonic Sensing: Principles and Applications for Safety and Security Monitoring SN - 9780470626955 SP - 89 EP - 118 DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 07aa9853-b419-47a2-b90d-7bb08b0c5edf ER - TY - JOUR TI - Tolerancing the fabrication errors of static optical elements for ELT-size wide-field AO systems DO - 10.1117/12.926321 AU - Véran, J.-P. AU - Pazder, J. AU - Herriot, G. AU - Andersen, D. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Adaptive Optics Systems III, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491480 VL - 8447 SP - 84471D KW - Deformable mirrors KW - Error budgets KW - Fabrication errors KW - Monte carlo analysis KW - Off-axis KW - Optical fabrication KW - Optical tolerancing KW - Sky coverage KW - Spatial scale KW - Thirty Meter Telescope KW - Tolerance analysis KW - Tolerancing KW - Wavefront errors KW - Wide field of view KW - Wide-field KW - Adaptive optics KW - Automobile manufacture KW - Budget control KW - Fabrication KW - Fits and tolerances KW - Polishing KW - Random errors KW - Wavefronts KW - Optics AB - Advanced wide-field AO systems, such as Multi-Conjugate AO (MCAO) systems often require many static optical elements (mirror and lenses) in addition to the active ones (deformable mirrors). These static elements induce additional wave-front errors due to random fabrication errors such as polishing errors. For ELT-size AO systems, these optical elements can be very large, and thus their cost and availability critically depends on how of much fabrication error can be tolerated. Therefore, a rigorous tolerance analysis is absolutely critical. Requirements can, in principle be relaxed, on account that fabrication errors with spatial scales larger than the inter-actuator spacing of the deformable mirrors (DMs) can be corrected. However, this process is significantly complicated by the fact that these optical elements are often conjugated far away from the DMs, and therefore DM correction cannot be achieved over a wide field of view (FOV). In this paper, we present our tolerance analysis in the context of NFIRAOS, the first-light MCAO system for the Thirty Meter Telescope. We start from two top-level error budgets: the "on-axis error budget, which specifies the acceptable residual wave-front error in the narrow 17''x17'' science FOV; and the "off-axis" error budget, which specifies the acceptable residual wave-front error at the edge of the 2' diameter technical FOV. The former directly relates to science image quality, whereas the latter directly relates to sky coverage. For different assumptions on the spatial power spectrum of the polishing errors, we derive the requirements on each optical element in NFIRAOS using a Monte-Carlo analysis of the predicted off-axis performance of the system with on axis AO correction. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 21b3a9eb-d76f-46d1-b7bf-3c552dd3dc70 ER - TY - JOUR TI - New developments in nanoparticle-liquid crystal composites: From magic-sized semiconductor nanoclusters to alignment pattern formation via nanoparticle stenciling DO - 10.1117/12.909022 AU - Mirzaei, J. AU - Sawatzky, R. AU - Sharma, A. AU - Urbanski, M. AU - Yu, K. AU - Kitzerow, H.-S. AU - Hegmann, T. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Emerging Liquid Crystal Technologies VII, 22 January 2012 through 25 January 2012, San Francisco, CA SN - 0277-786X SN - 9780819489227 VL - 8279 SP - 827913 KW - liquid crystal alignment KW - nematic KW - Pattern formation KW - Quantum Dot KW - stenciling KW - Cadmium alloys KW - Cadmium compounds KW - Defects KW - Doping (additives) KW - Electrooptical devices KW - Energy gap KW - Glass KW - Gold KW - Liquid crystals KW - Nanocrystals KW - Nanoparticles KW - Nematic liquid crystals KW - Polyimides KW - Semiconductor doping KW - Semiconductor quantum dots KW - Zinc KW - Alignment AB - We here report on the alignment and electro-optic properties of nematic liquid crystals (LCs) either containing nanoscale particles as additives or featuring particles patterned on substrates. The investigated nematic LCs or LC dispersions are doped or in contact with magic-sized semiconductor CdSe nanocrystals (MSNCs) or silane- and alkylthiol monolayercapped gold nanoparticles. Three single-sized CdSe quantum dots capped with myristic acid exhibiting bright bandgap photoluminescence (PL) at λ max ∼ 463 nm were tested as additives. Two of the quantum dots only vary in the amount of defects as indicated by different bandgap and deep trap PL. The third MSNC sample is compositionally different, doped with Zn. These MSNCs with almost identical sizes were doped at different concentrations (1-5 wt%) into the nematic phase of the 2-phenylpyrimidine-based LC1. Only the Zn-doped MSNCs showed the formation of birefringent stripes surrounded by areas of homeotropic alignment between plain glass slides at all concentrations as observed for many other nanoparticle-doped nematic LCs reported earlier by our group. In polyimide-coated glass slides favoring planar orientation of the nematic director, planar alignment was observed. Similarly, siloxane-coated gold nanoparticle additives with narrow size distribution, but larger size, show homeotropic alignment between plain glass and planar alignment in rubbed polyimide-coated cells. Surprisingly then, we succeeded in creating alignment patterns using smaller, ∼2 nm alkylthiol-capped gold nanoparticles using a process called stenciling that allowed us to generate patterns of homeotropic alignment in a continuum of planar alignment of the nematic LC. Finally, electro-optic investigations on some of these samples revealed that only the Zn-doped magic-sized MSNCs significantly lower the dielectric anisotropy as well as the splay elastic constant of the nematic host, despite identical size and surface functionality of the three used MSNCs, which highlights the tremendous effect of the nanocrystal core composition on the electro-optic properties of the nematic host. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE). DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 19081b12-0215-41e5-8624-12f78ca9ef17 ER - TY - JOUR TI - The HIA MCAO laboratory bench DO - 10.1117/12.927236 AU - Véran, J.-P. AU - McWeigh, E. AU - Andersen, D. AU - Correia, C. AU - Herriot, G. AU - Pazder, J. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Adaptive Optics Systems III, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491480 VL - 8447 SP - 844750 KW - Calibration procedure KW - Closed-loop KW - Controlled conditions KW - End-to-end simulation KW - Laboratory experiments KW - Multiconjugate adaptive optics KW - Non-uniformities KW - Optimization method KW - Scaled-down versions KW - Second time scale KW - Shack-Hartmann KW - Sodium layer KW - Thirty Meter Telescope KW - Tomographic KW - Tomographic reconstruction KW - MATLAB KW - Sodium KW - Tomography KW - Adaptive optics AB - This paper presents an update on the design and deployment of the HIA MCAO laboratory bench. This bench directly supports the development of NFIRAOS, the first light MCAO facility for the Thirty Meter Telescope. The bench implements a closed-loop MCAO system, with two magnetic DMs, four LGS Shack-Hartmann WFSs, two NGS T/T WFS, one NGS T/T/F WFS and one higher order Truth WFS, making up a scaled down version of NFIRAOS. The bench includes several artificial turbulence screens and reproduces realistic LGS spot elongations. It is driven by software in Matlab, frame-rates ranging from 1Hz to 15Hz. The goals of this bench are to anchor the NFIRAOS end-to-end simulation tools; to exercise real-time LGS tomographic AO in a variety of well controlled conditions, such as faint and poorly corrected NGSs, non-uniformities in the sodium layer and field dependant Non-Common-Path Aberrations (NCPAs); develop and demonstrate calibration procedures, such as PSF reconstruction and tomographic reconstruction and correction of field dependant NCPAs; and to validate optimization methods that operate at 10+ second time scales, which is not tractable in a numerical simulation, such as matched filter update and Cn2 estimation using a SLODAR method. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b58ee6d5-589d-4689-ac41-61a2dd4ce0b0 ER - TY - CHAP TI - Preface AU - Xiao, G. AU - Bock, W.J. T2 - Photonic Sensing: Principles and Applications for Safety and Security Monitoring SN - 9780470626955 SP - XI EP - X DA - 2012 PY - 2012 PB - Wiley LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3945914f-b6b6-4662-9f3e-6d3ea6d175e6 ER - TY - JOUR TI - The optical alignment of the Gemini planet imager adaptive optics bench DO - 10.1117/12.925866 AU - Pazder, J. AU - Bauman, B. AU - Dillon, D. AU - Fletcher, M. AU - Lacoursièred, J. AU - Reshetova, V. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Modern Technologies in Space- and Ground-Based Telescopes and Instrumentation II, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491510 VL - 8450 SP - 845058 KW - Astronomical instrumentation KW - FaroArm KW - Gemini telescopes KW - Off-axis KW - Optical alignments KW - Shack-Hartmann wavefront sensors KW - Helium neon lasers KW - Mirrors KW - Optical telescopes KW - Telescopes KW - Wavefronts KW - Alignment AB - The Gemini Planet Imager (GPI) is a facility instrument under construction for the 8-m Gemini South telescope. This paper describes the methods used for optical alignment of the adaptive optics (AO) bench. The optical alignment of the off-axis paraboloid mirrors was done using a pre-alignment method utilizing a HeNe laser and alignment telescopes followed by a fine-tuning using a Shack-Hartmann wavefront sensor and a shear plate. A FARO arm measuring system was used to place the fiducials for the alignment. Using these methods the AO bench was aligned to 13nm RMS of wavefront error. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 05acbca5-d024-43d2-b9c3-a946491759ec ER - TY - JOUR TI - GRACES, the gemini remote access CFHT ESPaDOnS spectrograph; initial design and testing DO - 10.1117/12.926626 AU - Tollestrup, E.V. AU - Pazder, J. AU - Barrick, G. AU - Martioli, E. AU - Schiavon, R.P. AU - Anthony, A. AU - Halman, M. AU - Veillet, C. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Ground-Based and Airborne Instrumentation for Astronomy IV, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491473 VL - 8446 SP - 84462A KW - Focal ratio degradation KW - High resolution KW - Initial design KW - Keck observatory KW - Laboratory test KW - Long fiber KW - Optical spectrograph KW - Remote access KW - Transmission loss KW - Astronomy KW - Optical fibers KW - Optical telescopes KW - Telescopes KW - Spectrographs AB - The Gemini Remote Access CFHT ESPaDOnS Spectrograph (GRACES) is an innovative instrumentation experiment that will demonstrate if ESPaDOnS, a bench-mounted high-resolution optical spectrograph at CFHT, can be fed by a 270-m long fiber from the Gemini-North telescope with low enough losses to remain competitive with conventional spectrographs on other 8 to 10-m telescopes. Detailed simulations have shown that GRACES should be more sensitive than the HIRES spectrograph at Keck Observatory at wavelengths longer than about 600-700 nm. This result is possible by using FPB-type of optical fibers made by Polymicro Technologies and by keeping the critical focal ratio degradation (FRD) losses to less than 10%. Laboratory tests on these FPB optical fibers are underway and show that for 36-m lengths that the FRD losses are as low as 0.8% with a repeatability of 1%. Tests are currently underway on 280-m lengths. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 311509c3-defe-4ec6-a038-68bfce8c571b ER - TY - JOUR TI - Vibrations in AO control: A short analysis of on-sky data around the world DO - 10.1117/12.925984 AU - Kulcsár, C. AU - Sivo, G. AU - Raynaud, H.-F. AU - Neichel, B. AU - Rigaut, F. AU - Christou, J. AU - Guesalaga, A. AU - Correia, C. AU - Véran, J.-P. AU - Gendron, É. AU - Vidal, F. AU - Rousset, G. AU - Morris, T. AU - Esposito, S. AU - Quirós-Pacheco, F. AU - Agapito, G. AU - Fedrigo, E. AU - Pettazzi, L. AU - Clare, R. AU - Muradore, R. AU - Guyon, O. AU - Martinache, F. AU - Meimon, S. AU - Conan, J.-M. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Adaptive Optics Systems III, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491480 VL - 8447 SP - 84471C KW - Adaptive optics systems KW - Disturbance identification KW - H2 control KW - High frequency vibration KW - Large binocular telescope KW - LQG control KW - Residual vibrations KW - Tip-tilt KW - Very large telescope KW - Vibration mitigation KW - Vibration peak KW - William herschel telescopes KW - Adaptive optics KW - Atmospheric turbulence KW - Controllers KW - Identification (control systems) KW - Optical telescopes KW - Power spectral density KW - Spectrum analysis KW - Telescopes KW - Vibrations (mechanical) KW - Discrete time control systems AB - We present in this paper an analysis of several tip-tilt on-sky data registered on adaptive optics systems installed on different telescopes (Gemini South, William Herschel Telescope, Large Binocular Telescope, Very Large Telescope, Subaru). Vibration peaks can be detected, and it is shown that their presence and location may vary, and that their origin is not always easy to determine. Mechanical solution that have been realized to mitigate vibrations are presented. Nevertheless, residual vibrations may still affect the instruments' performance, ranging from narrow high frequency vibration peaks to wide low frequency windshake-type perturbations. Power Spectral Densities (PSDs) of on-sky data are presented to evidence these features. When possible, indications are given regarding the gain in performance that could be achieved with adequate controllers accounting for vibration mitigation. Two examples of controller identification and design illustrate their ability to compensate for various types of disturbances (turbulence, windshake, vibration peaks, ...), showing a significant gain in performance. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b1e2132b-5437-4a8e-a272-c166359b8ed2 ER - TY - JOUR TI - Improved stress intensity factor solution for cracks in panels with arbitrarily located stringers DO - 10.2514/6.2012-1699 AU - Bombardier, Yan AU - Liao, Min AU - Renaud, Guillaume T2 - 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference T2 - Collection of Technical Papers T3 - 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, 23 April 2012 through 26 April 2012, Honolulu, HI SN - 0273-4508 SN - 9781600869372 SP - AIAA 2012-1699 KW - A-center KW - Closed form solutions KW - Crack location KW - Edge cracks KW - Linear statics KW - Poisson's effects KW - Cracks KW - Locks (fasteners) KW - Stress intensity factors KW - Structural dynamics KW - Stringers AB - This paper presents a stress intensity factor solution for cracks located in panels reinforced with arbitrarily located stringers. The new solution was developed by modifying the constituting equations of a solution for symmetrically and periodically spaced stringers with riveted rigid fasteners. The new solution supports arbitrary stringer locations with respect to the crack location, includes the capability to model compliant fasteners, improves the accuracy of the equivalent stringer compliance by considering Poisson's effect, and allows the fasteners to be arbitrarily located within each stringer. The stress intensity factors calculated using the new closed-form solution were compared to linear static finite element analysis results and very good agreement was obtained for the tested cases. Through two examples for the CC-130 aircraft, it was shown that the closed-form solution developed for a center crack in an infinite sheet could also be used to model an edge crack growing in a relatively large panel. DA - 2012/04 PY - 2012 PB - American Institute of Aeronautics and Astronautics LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fe6d58d2-0fcc-4f51-87a4-53811e359713 ER - TY - JOUR TI - Identification of aeroelastic parameters for cormorant tail rotor structures based on vibration measurement in the stationary frame AU - Chen, Y. AU - Wickramasinghe, V. AU - Zimcik, D.G. T2 - Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference T3 - 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, 23 April 2012 through 26 April 2012, Honolulu, HI SN - 0273-4508 SN - 9781600869372 SP - AIAA 2012-1479 KW - Aero-elastic simulations KW - Center frequency KW - Flight conditions KW - Helicopter fleets KW - High-amplitude vibrations KW - Identified parameter KW - Limit Cycle Oscillation (LCO) KW - Stationary frame KW - Aeroelasticity KW - Structural dynamics KW - Helicopter rotors AB - The teetering tail rotor of the Canadian CH-149 Cormorant helicopter fleet experienced limit cycle oscillation (LCO) phenomenon in certain adverse flight conditions in which the transient high amplitude vibration resulted in significant increase of dynamic strain to the tail rotor structures. This could contribute to pre-mature damage of the composite half hub among other causes. Therefore it is required to evaluate the integrity of the tail rotor structure using realistic aeroelastic parameters of the tail rotor in the rotating frame. This paper presents a novel center frequency scaling factor theory and related parameter identification methodologies in order to estimate and track the variation of the critical aeroelastic parameters in the rotating frame during LCO events based on vibration information measured exclusively in the stationary frame. This information would enable update of the tail rotor stability diagram in order to confidently evaluate the impact of LCO events to the structural integrity of the Cormorant tail rotor structures. Based on the developed procedures and identified parameters, recommendations are provided for data analysis and techniques to improve the fidelity of results from aeroelastic simulation analysis for the Cormorant tail rotor structures without the need to install sensors in the rotating frame. © 2012 AIAA. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 79f59eab-defd-42c0-b44d-290688e7def5 ER - TY - JOUR TI - Microfluidic control of adipose-derived stem cell growth and positioning AU - Lin, F. AU - Wadhawan, N. AU - Kalkat, H. AU - Ma, X. AU - Gajjeraman, S. AU - Nandagopal, S. AU - Hao, N. AU - Deng, J. AU - Xiang, B. AU - Zhang, M. AU - Tian, G. T2 - Nanotechnology 2012: Technical Proceedings of the 2012 NSTI Nanotechnology Conference and Expo. Volume 2: Electronics, devices, fabrication, MEMS, fluidics and computational. T3 - Nanotech Conference and Expo 2012, June 18-21, 2012, Santa Clara, CA, USA SN - 9781466562752 SP - 306 EP - 309 KW - Adipose derived stem cells KW - Cell migration KW - Chemical factors KW - Conventional methods KW - Direct current electric fields KW - EGF KW - Epidermal growth factors KW - Micro-fluidic devices KW - Microfluidic control KW - Physical parameters KW - Stem cell research KW - Cell growth KW - Electric fields KW - Exhibitions KW - Fabrication KW - Fluidic devices KW - Growth kinetics KW - Nanotechnology KW - Stem cells KW - Microfluidics AB - Microfluidic devices provide powerful new tools for quantitative stem cell research owing to its advantages in cellular microenvironmental control and experiment throughput over conventional methods. Particularly, microfluidics is playing a growing role in studying stem cell growth, differentiation and trafficking mediated by chemical factors such as different growth and differentiation factors and physical parameters such as direct current electric fields (dcEF). In the present study, we focused on adipose-derived stem cells (ADSCs) and we quantitatively characterized ADSCs growth and positioning mediated by epidermal growth factor (EGF) and dcEF using microfluidic devices. Our results revealed mat ADSCs preferentially grow toward the EGF gradient. In addition, we showed that ADSCs tend to orient perpendicularly to the dcEF. These microfluidics-based results demonstrated the interesting roles of EGF and dcEF in controlling ADSCs growth and trafficking. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2310775d-48e9-431f-9b57-4c2280b648f1 ER - TY - JOUR TI - Dynamical thermal effects in InGaAsP microtubes at telecom wavelengths DO - 10.1364/OL.37.002712 AU - Tian, Z. AU - Bianucci, P. AU - Roche, P.J.R. AU - Dastjerdi, M.H.T. AU - Mi, Z. AU - Poole, P.J. AU - Kirk, A.G. AU - Plant, D.V. T2 - Optics Letters SN - 0146-9592 VL - 37 IS - 13 SP - 2712 EP - 2714 KW - Active application KW - Bi-layer KW - InAs quantum dots KW - Induced thermal effects KW - InGaAsP KW - Micro-tubes KW - Photon absorptions KW - Resonance wavelengths KW - Tapered optical fibers KW - Telecom wavelengths KW - Tube structures KW - Indium arsenide KW - Optical fiber coupling KW - Optical fiber fabrication KW - Wavelength AB - We report on the observation of a dynamical thermal effect in InGaAsP microtubes at telecom wavelengths. The microtubes are fabricated by releasing a strained semiconductor bilayer and are picked up by abruptly tapered optical fibers for subsequent coupling with adiabatically tapered optical fibers. As a result of absorption by InAs quantum dots embedded in the tube structure, these microtubes show dynamical thermal effects at wavelengths around 1525 nm and 1578 nm, while they are passive at longer wavelengths near 1634 nm. The photon absorption induced thermal effect is visualized by generating a pair of microbottles. The dynamical thermal effect can be avoided or exploited for passive or active applications by utilizing appropriate resonance wavelengths. © 2012 Optical Society of America. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 815cf513-838f-4f27-b777-d7dc2eac9be2 ER - TY - JOUR TI - Carrier dynamics in type-II GaAsSb/GaAs quantum wells DO - 10.1088/0953-8984/24/18/185801 AU - Baranowski, M. AU - Syperek, M. AU - Kudrawiec, R. AU - Misiewicz, J. AU - Gupta, J.A. AU - Wu, X. AU - Wang, R. T2 - Journal of Physics Condensed Matter SN - 0953-8984 VL - 24 IS - 18 SP - 185801 AB - Time-resolved photoluminescence (PL) characteristics of type-II GaAsSb/GaAs quantum wells are presented. The PL kinetics are determined by the dynamic band bending effect and the distribution of localized centers below the quantum well band gap. The dynamic band bending results from the spatially separated electron and hole distribution functions evolving in time. It strongly depends on the optical pump power density and causes temporal renormalization of the quantum well ground-state energy occurring a few nanoseconds after the optical pulse excitation. Moreover, it alters the optical transition oscillator strength. The measured PL lifetime is 4.5ns. We point out the critical role of the charge transfer processes between the quantum well and localized centers, which accelerate the quantum well photoluminescence decay at low temperature. However, at elevated temperatures the thermally activated back transfer process slows down the quantum well photoluminescence kinetics. A three-level rate equation model is proposed to explain these observations. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5df2156c-305c-47df-8bed-3de9f4780245 ER - TY - JOUR TI - Transcripts of sulphur metabolic genes are co-ordinately regulated in developing seeds of common bean lacking phaseolin and major lectins DO - 10.1093/jxb/ers280 AU - Liao, D. AU - Pajak, A. AU - Karcz, S.R. AU - Patrick Chapman, B. AU - Sharpe, A.G. AU - Austin, R.S. AU - Datla, R. AU - Dhaubhadel, S. AU - Marsolais, F. T2 - Journal of Experimental Botany SN - 0022-0957 VL - 63 IS - 17 SP - 6283 EP - 6295 KW - amino acid KW - cysteine KW - drug derivative KW - lectin KW - messenger RNA KW - methionine KW - o acetylserine KW - O-acetylserine KW - phaseolin protein, Phaseolus vulgaris KW - plant RNA KW - s methylcysteine KW - S-methylcysteine KW - seed storage protein KW - serine KW - sulfur KW - vegetable protein KW - article KW - cluster analysis KW - DNA microarray KW - gene expression profiling KW - gene expression regulation KW - genetics KW - growth, development and aging KW - metabolism KW - Phaseolus KW - plant seed KW - Amino Acids KW - Cluster Analysis KW - Cysteine KW - Gene Expression Profiling KW - Gene Expression Regulation, Plant KW - Lectins KW - Methionine KW - Oligonucleotide Array Sequence Analysis KW - Phaseolus KW - Plant Proteins KW - RNA, Messenger KW - RNA, Plant KW - Seed Storage Proteins KW - Seeds KW - Serine KW - Sulfur KW - Phaseolus vulgaris AB - The lack of phaseolin and phytohaemagglutinin in common bean (dry bean, Phaseolus vulgaris) is associated with an increase in total cysteine and methionine concentrations by 70% and 10%, respectively, mainly at the expense of an abundant non-protein amino acid, S-methyl-cysteine. Transcripts were profiled between two genetically related lines differing for this trait at four stages of seed development using a high density microarray designed for common bean. Transcripts of multiple sulphur-rich proteins were elevated, several previously identified by proteomics, including legumin, basic 7S globulin, albumin-2, defensin, albumin-1, the Bowman-Birk type proteinase inhibitor, the double-headed trypsin inhibitor, and the Kunitz trypsin inhibitor. A co-ordinated regulation of transcripts coding for sulphate transporters, sulphate assimilatory enzymes, serine acetyltransferases, cystathionine β-lyase, homocysteine S-methyltransferase and methionine gamma-lyase was associated with changes in cysteine and methionine concentrations. Differential gene expression of sulphur-rich proteins preceded that of sulphur metabolic enzymes, suggesting a regulation by demand from the protein sink. Up-regulation of SERAT1;1 and-1;2 expression revealed an activation of cytosolic O-acetylserine biosynthesis. Down-regulation of SERAT2;1 suggested that cysteine and S-methyl-cysteine biosynthesis may be spatially separated in different subcellular compartments. Analysis of free amino acid profiles indicated that enhanced cysteine biosynthesis was correlated with a depletion of O-acetylserine. These results contribute to our understanding of the regulation of sulphur metabolism in developing seed in response to a change in the composition of endogenous proteins. © 2012 The Author. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 571a086b-3ed3-4e98-8ea3-21681e385e9a ER - TY - JOUR TI - Evolution of microstructure, microtexture and mechanical properties of linear friction welded IMI 834 DO - 10.1179/1879139512Y.0000000014 AU - Dalgaard, E. AU - Wanjara, P. AU - Gholipour, J. AU - Jonas, J.J. T2 - Canadian Metallurgical Quarterly SN - 0008-4433 VL - 51 IS - 3 SP - 269 EP - 276 KW - Aerospace KW - Aerospace manufacturing KW - Axial pressures KW - Bladed rotors KW - Compressor discs KW - Digital image correlations KW - EBSD analysis KW - Electron back scatter diffraction KW - Fatigue strength KW - Fusion welding KW - High tech KW - IMI834 KW - Linear friction KW - Linear friction welding KW - Mechanical fastening KW - Micro-texture KW - Microstructural examination KW - Parent materials KW - Phase fractions KW - Thermomechanically affected zones KW - Weld zone KW - Weldments KW - Aerospace industry KW - Friction welding KW - Microstructural evolution KW - Molybdenum KW - Niobium KW - Recrystallization (metallurgy) KW - Tensile testing KW - Textures KW - Tin KW - Titanium alloys KW - Welding KW - Welds KW - Zirconium KW - Creep resistance AB - Titanium alloys have been of great interest in the aerospace industry for many years. Recently, linear friction welding has also been making strides in conquering a part of the aerospace manufacturing market, with its clear advantages over fusion welding and mechanical fastening methods for integrated bladed rotors. High tech near-α alloy IMI834 (Ti-5·8Al-4Sn- 3·5Zr-0·7Nb- 0·5Mo-0·35Si) was designed to have improved creep resistance and retains its mechanical properties at temperatures up to 600°C. It balances creep resistance and fatigue strength, making it an excellent material for compressor discs and blades. IMI834 with an initial bimodal αzb microstructure was welded using varying axial pressures during welding and then characterised using both microstructural examination and mechanical testing. Electron backscatter diffraction (EBSD) was used to characterise the texture and phase fraction of the welded IMI834 samples in the weld zone (WZ) and thermomechanically affected zones. The EBSD analysis revealed fine recrystallised grains at the weld centres. The microhardness evaluation of the weldments showed that the recrystallised WZ was slightly harder than the parent material (PM). The local and global tensile properties of the welds, investigated using a tensile testing rig with integrated digital image correlation, revealed higher strength in the WZ and failure in the PM. © 2012 Crown in Right of Canada. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bddb1f08-4028-41a9-98bb-12d68beb9beb ER - TY - JOUR TI - Effect of circular tool path on cutting force profile in micro-end-milling DO - 10.1177/0954406211423575 AU - Banerjee, A. AU - Bordatchev, E.V. T2 - Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science SN - 0954-4062 VL - 226 IS - 6 SP - 1589 EP - 1600 KW - Chip thickness KW - Cutting force measurements KW - Cutting force signals KW - Cutting forces KW - End-milling KW - Feed-rates KW - Material removal KW - Micro milling KW - Micro-end-milling KW - Rotation angles KW - Rotational speed KW - Toolpaths KW - Cutting KW - Micromachining KW - Milling (machining) KW - Signal processing KW - Scanning AB - Micro-end-milling requires high spindle rotational speed to achieve effective material removal. This results in the requirement of tool stoppage or slowdown during a micro-end-milling operation, a deterrent to productivity and to part acceptability. A circular tool path geometry can avoid discontinuities in the tool movements leading to a more consistent and smooth material removal. However, optimal process planning for such a tool path will require detailed understanding of the chip-formation mechanism in circular end-milling. The cut geometry during end-milling along a circular tool path is often approximated as that of a linear tool path. Although this assumption works well for circular tool paths with higher tool path radius, this is not the case for lower tool path radius often used in micro-milling. In this study, the effect of circular tool path on the cutting force for varying tool path rotation angle, tool path radius, and feed rate is experimentally investigated. Systematic signal processing was applied to analyse the measured cutting force signal along linear and several circular tool paths. Qualitative as well as quantitative differences were observed in the cutting force profiles obtained using different tool path radii, tool path orientations, and feed rates. This implies the need for an improved chip thickness formulation dedicated to micro-end-milling with circular tool path rather than approximating it with formulations derived for linear tool path. © Authors 2011. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d8a395e9-52b5-4682-ae0b-e04ecb1c96e4 ER - TY - JOUR TI - A Novel Role for the Transcription Factor Cwt1p as a Negative Regulator of Nitrosative Stress in Candida albicans DO - 10.1371/journal.pone.0043956 AU - Sellam, A. AU - Tebbji, F. AU - Whiteway, M. AU - Nantel, A. T2 - PLoS ONE SN - 1932-6203 VL - 7 IS - 8 SP - e43956 KW - transcription factor KW - transcription factor Cwt1p KW - unclassified drug KW - article KW - Candida albicans KW - controlled study KW - fungal genome KW - fungus mutant KW - gene activation KW - gene expression KW - gene expression profiling KW - gene location KW - gene regulatory network KW - gene repression KW - genetic analysis KW - host cell KW - nitrosative stress KW - nonhuman KW - phagocyte KW - regulon KW - transcription regulation KW - Candida albicans KW - Fungal Proteins KW - Gene Expression Profiling KW - Gene Expression Regulation, Fungal KW - Genomics KW - Oxygenases KW - Promoter Regions, Genetic KW - Reactive Nitrogen Species KW - Stress, Physiological KW - Transcription Factors KW - Transcription, Genetic KW - Candida albicans KW - Fungi KW - Mammalia AB - The ability of Candida albicans to survive in the presence of nitrosative stress during the initial contact with the host immune system is crucial for its ability to colonize mammalian hosts. Thus, this fungus must activate robust mechanisms to neutralize and repair nitrosative-induced damage. Until now, very little was known regarding the regulatory circuits associated with reactive nitrogen species detoxification in fungi. To gain insight into the transcriptional regulatory networks controlling nitrosative stress response (NRS) in C. albicans a compilation of transcriptional regulator-defective mutants were screened. This led to the identification of Cwt1p as a negative regulator of NSR. By combining genome-wide location and expression analyses, we have characterized the Cwt1p regulon and demonstrated that Cwt1p is directly required for proper repression of the flavohemoglobin Yhb1p, a key NO-detoxification enzyme. Furthermore, Cwt1p operates both by activating and repressing genes of specific functions solicited upon NSR. Additionally, we used Gene Set Enrichment Analysis to reinvestigate the C. albicans NSR-transcriptome and demonstrate a significant similarity with the transcriptional profiles of C. albicans interacting with phagocytic host-cells. In summary, we have characterized a novel negative regulator of NSR and bring new insights into the transcriptional regulatory network governing fungal NSR. © 2012 Sellam et al. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 34be012a-2267-48bd-9143-3d9a9efd673f ER - TY - JOUR TI - Flight test evaluation of a prototype optical instrument for airborne sense-and-avoid applications DO - 10.1117/12.918641 AU - Minwalla, C. AU - Thomas, P. AU - Ellis, K. AU - Hornsey, R. AU - Jennings, S. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Unmanned Systems Technology XIV, 25 April 2012 through 27 April 2012, Baltimore, MD SN - 0277-786X SN - 9780819490650 VL - 8387 SP - 83870R KW - COTS KW - Flight test KW - MTF KW - sense-and-avoid KW - Smart nodes KW - SNR KW - UAS KW - Accident prevention KW - Aircraft accidents KW - Bells KW - Helicopters KW - Sensors KW - Instruments AB - A prototype, wide-field, optical sense-and-avoid instrument was constructed from low-cost commercial off-the-shelf components, and configured as a network of smart camera nodes. To detect small, general-aviation aircraft in a timely manner, such a sensor must detect targets at a range of 5-10 km at an update rate of a few Hz. This paper evaluates the flight test performance of the "DragonflEYE" sensor as installed on a Bell 205 helicopter. Both the Bell 205 and the Bell 206 (intruder aircraft) were fully instrumented to record position and orientation. Emphasis was given to the critical case of head-on collisions at typical general aviation altitudes and airspeeds. Imagery from the DragonflEYE was stored for the offline assessment of performance. Methodologies for assessing the key figures of merit, such as the signal-to-noise ratio, the range at first detection (R0) and angular target size were developed. Preliminary analysis indicated an airborne detection range of 6:7 km under typical visual meteorological conditions, which significantly exceeded typical visual acquisition ranges under the same conditions. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE). DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4c8a0d50-5cd5-47d5-9642-aff4e9019ef0 ER - TY - CHAP TI - Preface AU - Liu, R. AU - Zhang, L. AU - Sun, X. AU - Liu, H. AU - Zhang, J. T2 - Electrochemical Technologies for Energy Storage and Conversion: volume 1 & 2 SN - 9783527328697 SN - 9783527639496 VL - 1 SP - XVII EP - XVIII DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5f2d7bab-78e2-406d-9880-a1ea384f8813 ER - TY - JOUR TI - Advanced control of low order modes in laser guide star multi-conjugate adaptive optics systems DO - 10.1117/12.926872 AU - Correia, C. AU - Véran, J.-P. AU - Herriot, G. AU - Ellerbroek, B. AU - Wang, L. AU - Gilles, L. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Adaptive Optics Systems III, 1 July 2012 through 6 July 2012, Amsterdam SN - 0277-786X SN - 9780819491480 VL - 8447 SP - 84471S KW - Advanced control KW - Anisoplanatism KW - Atmospheric tomography KW - Double integrator KW - Kalman-filtering KW - Laser guide star KW - Low order KW - Lower bounds KW - Modal gain KW - Multi-conjugate adaptive optics systems KW - Parameter optimisation KW - Thirty Meter Telescope KW - Lasers KW - Mineralogy KW - Optimization KW - Stars AB - Laser-guide-star-based multi-conjugate adaptive optics (MCAO) systems require natural guide-stars to measure tilt and tilt-anisoplanatism modes. This paper focuses on the parameter optimisation of sub-optimal integrator-based controllers using a single and a double integrator (baseline option) to drive the low-order loop of NFIRAOS, the 1st light MCAO system for the Thirty-Meter Telescope. The minimum-variance (MV) controller is outlined, against which integrators are compared. Simulations using ∼500 asterisms considered in sky-coverage simulations for the TMT show that the double integrator gives competitive results thoughout the range of asterisms and magnitudes considered. It is shown that using an optimal modal gain integrator can further improve the performance with respect to using an averaged gain for all of part of the modes. However, it is outperformed by the MV controller, in particular for asterisms with relatively dim stars (lower bound is magnitude 22 in H-band) requiring low temporal frame-rates (as low as 16Hz) to integrate more flux. Over all the cases tested, an average of ∼100 nm rms (23 nm rms median) improvement can be achieved with the MV. The MV further increases by 15% the probability of working below the 50th-percentile residual of the double integrator. © 2012 SPIE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 14337dcd-f395-43c7-8ad2-58e594044b2d ER - TY - JOUR TI - Evaluation of sealed joint performance for the selection of sealants suitable for use in autoclaved lightweight concrete panels DO - 10.1520/JAI104064 AU - Miyauchi, H. AU - Lacasse, M. A. AU - Murata, S. AU - Enomoto, N. AU - Tanaka, K. T2 - Journal of ASTM International SN - 1546-962X VL - 9 IS - 1 KW - Cyclic fatigue KW - Earthquake load KW - Expansion and contraction KW - External walls KW - Fatigue tests KW - Joint fracture KW - Joint movement KW - Joint performance KW - Lightweight concrete panel KW - Long term performance KW - Low modulus KW - Modulus KW - Normal concretes KW - Sealant products KW - Shear joints KW - Shear tests KW - Static and dynamic KW - Test specimens KW - Two-component KW - Wall panels KW - Adhesion KW - Concrete slabs KW - Fatigue of materials KW - Fatigue testing KW - Fracture KW - Precast concrete KW - Substrates KW - Testing KW - Walls (structural partitions) KW - Sealants AB - The strength of autoclaved lightweight concrete (ALC) is evidently lower than that of normal concrete. Therefore, when movement occurs at a sealed joint between ALC panels, the sealant is required to deform and remain intact without damaging the ALC substrate. However, there is currently not sufficient information to permit evaluation of the expected performance of sealants applied to ALC substrates. In this study, static and dynamic tests were carried out in order to obtain an index that could be used to select the modulus of a sealant that can be expected to provide long-term performance when applied to an ALC substrate. To develop this index, an initial study was carried out in order to clarify actual joint movement between ALC panels of buildings; the expansion and contraction at the joint were measured, and shear joint movement was calculated based on the expected story-to-story drift of an external wall due to earthquake loads. Thereafter, in a subsequent stage of the study, five types of two-component polyurethane sealant products, of different elastic modulus, were subjected to tensile and shear tests from which the relationship between stress and the type of joint fracture was determined. The results from these tests revealed that when the stress is greater than 0.6 to 0.7 N/mm 2, the ALC substrate is more easily fractured than the sealant. In a final stage of the study, the cyclic fatigue resistance of the same two-component sealants was evaluated using tensile and shear fatigue tests. Results from the fatigue tests indicated that the high modulus sealants lost adhesion from the ALC substrate at an early stage in the test. As well, the fatigue resistance of test specimens with joints having three-sided adhesion was lower than that of specimens having normally configured joints with adhesion on two sides of the sealant. Therefore, on the basis of results derived from all the studies, it was determined that a suitable sealant for use on ALC substrates is a sealant having a low modulus that is applied in the normal fashion as a two-sided joint DA - 2012/01/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0d6ee191-428e-43ad-b0df-970281bcb2f6 ER - TY - JOUR TI - Ecotoxicity of canola and tallow biodiesel blends to selected soil organisms AU - Rocheleau, S. AU - Sarrazin, M. AU - Dodard, S. AU - Beaulieu, C. AU - Hawari, J. AU - Hollebone, B.P. AU - Yang, Z. AU - Sunahara., G. T2 - Proceedings of the 35th AMOP Technical Seminar on Environmental Contamination and Response T3 - 35th AMOP Technical Seminar on Environmental Contamination and Response, 5 June 2012 through 7 June 2012, Vancouver, BC SP - 1 EP - 12 KW - Accidental release KW - Advanced fuels KW - Aquatic toxicity KW - Biodiesel blends KW - Dehydrogenase activity KW - Deleterious effects KW - Direct contact KW - Dry soil KW - Earthworm Eisenia fetida KW - Ecotoxicity KW - Energy research and development KW - Environmental concerns KW - Fossil fuel resources KW - Lolium perenne KW - n-Alkanes KW - Petroleum diesel KW - Seedling emergence KW - Soil organisms KW - Toxicity assays KW - Toxicity test KW - Contamination KW - Fossil fuels KW - Paraffins KW - Soils KW - Sulfur KW - Technical presentations KW - Toxicity KW - Biodiesel AB - In view of depleting fossil fuel resources and environmental concern, biodiesel couldpotentially replace petroleum-derived diesel. Aquatic toxicity of diesel and biodiesel has beenextensively studied over the past decades but little is still known about their toxicity in soilenvironment. The scope of this study was to evaluate the environmental impact of biodiesel,biodiesel blends and petroleum diesel in soil using direct contact toxicity assays. The selectedbiodiesels included canola-source biodiesel (B100 and B20). and tallow-source biodiesel (B100and B20), which were compared to petroleum ultra-low-sulfur based diesel (ULSD). Selectedstandard terrestrial toxicity tests included ryegrass Lolium perenne seedling emergence andgrowth, earthworm Eisenia fetida survival, and soil microbial dehydrogenase activity. Soilcharacterization included the quantification of total extractable materials (corresponding to the n-alkane range of C10-C34). Preliminary results indicate that: 1) canola and tallow B20 biodieselblends were less toxic to earthworm than ULSD; 2) canola and tallow B20 blends had similartoxic effects to ryegrass as ULSD; and 3) petroleum ULSD inhibited the DHA activity at allconcentrations tested, and B20 canola biodiesel had a deleterious effect on the DHA activity atthe lowest nominal loadings tested (1 and 10 ml/kg dry soil). Therefore, this study providesuseful toxicological data for the evaluation of potential adverse impact of biodiesel in theenvironment, such as an accidental release or spill. This project was funded by EnvironmentCanada and Natural Resources Canada and is part of the Advanced Fuels and Technologies forEmissions Reduction (AFTER) Program for energy research and development (PERD). DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 01e96db9-3722-4cec-96ba-8b2e47dd7b72 ER - TY - JOUR TI - Spin textures in strongly coupled electron spin and magnetic or nuclear spin systems in quantum dots DO - 10.1103/PhysRevLett.108.247203 AU - Abolfath, R.M. AU - Korkusinski, M. AU - Brabec, T. AU - Hawrylak, P. T2 - Physical Review Letters SN - 0031-9007 VL - 108 IS - 24 SP - 247203 KW - Ab initio KW - Antiferromagnetics KW - Break down KW - Coupling strengths KW - Critical temperatures KW - Density-functional approach KW - Electron spins KW - Electronic charges KW - Electronic systems KW - Low temperatures KW - Magnetic ions KW - Magnetopolarons KW - Mean field approximation KW - Nuclear spin system KW - Nuclear spins KW - Semiconductor nanostructures KW - Solid-state system KW - Spin densities KW - Spin systems KW - Spin textures KW - Spontaneous symmetry breaking KW - Strongly coupled spin system KW - Antiferromagnetism KW - Computational linguistics KW - Electrospinning KW - Ions KW - Magnetic moments KW - Phase diagrams KW - Quantum computers KW - Semiconductor quantum dots KW - Temperature KW - Textures KW - Spin dynamics AB - Controlling electron spins strongly coupled to magnetic and nuclear spins in solid state systems is an important challenge in the field of spintronics and quantum computation. We show here that electron droplets with no net spin in semiconductor quantum dots strongly coupled with magnetic ion or nuclear spin systems break down at low temperature and form a nontrivial antiferromagnetic spatially ordered spin texture of magnetopolarons. The spatially ordered combined electron-magnetic ion spin texture, associated with spontaneous symmetry breaking in the parity of electronic charge and spin densities and magnetization of magnetic ions, emerges from an ab initio density functional approach to the electronic system coupled with mean-field approximation for the magnetic or nuclear spin system. The predicted phase diagram determines the critical temperature as a function of coupling strength and identifies possible phases of the strongly coupled spin system. The prediction may arrest fluctuations in the spin system and open the way to control, manipulate, and prepare magnetic and nuclear spin ensembles in semiconductor nanostructures. © 2012 American Physical Society. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b9ca551d-31f0-497c-ba94-514484c75de3 ER - TY - CHAP TI - Miniaturized Fiber Bragg Grating Sensor Systems for Potential Air Vehicle Structural Health Monitoring Applications DO - 10.1002/9781118310212.ch6 AU - Guo, H. AU - Xiao, G. AU - Mrad, N. AU - Yao, J. T2 - Photonic Sensing: Principles and Applications for Safety and Security Monitoring SN - 9780470626955 SP - 183 EP - 223 DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : dd4769dd-5503-48b0-bc4b-ed12f05abc87 ER - TY - JOUR TI - Effect of the nonresonant background medium in CARS and SRS microscopy image formation AU - Popov, K.I. AU - Pegoraro, A.F. AU - Stolow, A. AU - Ramunno, L. T2 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012 T3 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012, 6 May 2012 through 11 May 2012, San Jose, CA SN - 9781467318396 SP - 6326595 KW - Background medium KW - Microscopy images KW - Nonresonant KW - Lasers KW - Coherent scattering AB - Using mathematical modeling and numerical simulations, we examine the image formation in CARS, FM-CARS, AM-SRS and FM-SRS nonlinear Raman-based modalities. We find that in the presence of a nonresonant spatially-nonuniform background medium, only the FM-SRS modality can be considered to be both background and distortion free. © 2012 OSA. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c2e30a19-ad4a-4d41-8bfc-113c11826869 ER - TY - JOUR TI - Ion channel screening: Advances in technologies and analysis DO - 10.3389/fphar.2012.00086 AU - Martina, M. T2 - Frontiers in Pharmacology SN - 1663-9812 VL - 3-May SP - 86 KW - bungarotoxin receptor KW - G protein coupled inwardly rectifying potassium channel KW - G protein coupled receptor KW - ion channel KW - potassium channel blocking agent KW - potassium channel HERG KW - unclassified drug KW - vu 573 KW - article KW - cell communication KW - degenerative disease KW - drug cost KW - drug research KW - drug safety KW - drug screening KW - drug targeting KW - heart muscle conduction system KW - heterologous expression KW - high throughput screening KW - human KW - laboratory automation KW - nerve cell membrane potential KW - nerve cell network KW - patch clamp KW - protein analysis DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bd54699a-5f6e-40d8-9cc8-baccfe05d630 ER - TY - JOUR TI - A limited role of p53 on the ability of a hexane fraction of American ginseng to suppress mouse colitis DO - 10.1155/2012/785739 AU - Poudyal, D. AU - Cui, X. AU - Mai Le, P. AU - Davis, T. AU - Hofseth, A.B. AU - Jin, Y. AU - Chumanevich, A.A. AU - Wargovich, M.J. AU - Nagarkatti, M. AU - Nagarkatti, P.S. AU - Windust, A. AU - Hofseth, L.J. T2 - Journal of Biomedicine and Biotechnology SN - 1110-7243 VL - 2012 SP - 785739 KW - ginseng extract KW - protein p53 KW - hexane KW - plant extract KW - protein p53 KW - American ginseng KW - animal experiment KW - animal model KW - animal tissue KW - antiinflammatory activity KW - apoptosis KW - article KW - cell cycle arrest KW - colon cancer KW - controlled study KW - gene mutation KW - ginseng KW - human KW - human cell KW - in vitro study KW - in vivo study KW - mouse KW - nonhuman KW - ulcerative colitis KW - animal KW - cell line KW - chemistry KW - colitis KW - colon KW - disease model KW - drug effect KW - fractionation KW - G1 phase cell cycle checkpoint KW - metabolism KW - nick end labeling KW - Panax KW - pathology KW - phytotherapy KW - Animals KW - Apoptosis KW - Cell Line KW - Chemical Fractionation KW - Colitis KW - Colon KW - Disease Models, Animal KW - G1 Phase Cell Cycle Checkpoints KW - Hexanes KW - Humans KW - In Situ Nick-End Labeling KW - Mice KW - Panax KW - Phytotherapy KW - Plant Extracts KW - Tumor Suppressor Protein p53 AB - Ulcerative colitis (UC) is debilitating and carries a high colon cancer risk. Apoptosis of inflammatory cells is a key mechanism regulating UC. We have recently shown that American ginseng (AG), and to a greater extent, a Hexane fraction of AG (HAG) can cause apoptosis and suppress mouse colitis through a p53-mediated mechanism. Here, we tested the hypothesis that HAG suppresses colitis through a p53 mechanism. We found only a limited impact of p53 in the ability of HAG to induce inflammatory cell apoptosis and suppress mouse colitis in vitro and in vivo. Finally, we asked whether HAG could cause cell cycle arrest of HCT116 colon cancer cells in vitro. Interestingly, HAG caused a G1 arrest of such cells independent of p53 status. Findings are significant because HAG suppresses colitis and associated colon cancer, and mutation in p53 is observed in most colitis-driven colon cancers. Therefore, HAG might be very effective in targeting the inflammatory cells and cancer cells since it induces apoptosis of inflammatory cells and cell cycle arrest in both p53(-/-) and WT p53 colon cancer cells. © Copyright 2012 Deepak Poudyal et al. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9c0a5aae-a70e-4c21-8cc0-f623c0747909 ER - TY - JOUR TI - Chemical microanalysis with cavity-enhanced optical waveguide devices DO - 10.1117/12.920231 AU - Loock, H.-P. AU - Barnes, J.A. AU - Bescherer, K. AU - Brzezinski, A. AU - Gagliardi, G. AU - Gribble, A. AU - Janz, S. AU - Ma, R. AU - Munzke, D. AU - Ongo, G. AU - Saunders, J. AU - Waechter, H. AU - Xu, D.-X. T2 - SPIE - International Society for Optical Engineering. Proceedings T3 - Photonics and Optoelectronics Meetings (POEM) 2011: Optoelectronic Sensing and Imaging, 2 November 2011 through 5 November 2011, Wuhan SN - 0277-786X SN - 9780819489890 VL - 8332 SP - 833204 KW - Cavity enhanced spectroscopy KW - cavity ring-down KW - microphotonics KW - microsphere resonators KW - Silicon-on-insulators KW - waveguide cavity KW - Adsorption KW - Ethylene KW - Light absorption KW - Microspheres KW - Nucleic acids KW - Resonators KW - Silica KW - Spectroscopy KW - Spheres KW - Wavelength KW - Refractive index AB - Three examples of cavity-enhanced measurements of refractive index and optical absorption are discussed. Using microphotonic silicon-on-insulator ring-resonators we determine the concentration of cyclohexane and m-xylene at detection levels of 300-3000 ppm. The gases are first absorbed into a siloxane polymer and its refractive index change is detected by a characteristic wavelength shift of the cavity resonance. In a second device phase-shift cavity ring-down spectroscopy is applied to simultaneously measure the optical absorption at two wavelengths of either a dye, nucleic acids or a pharmaceutical component. Multiplexing the ring-down measurement permits dual wavelength absorption spectroscopy without the use of a dispersion element. Finally, a combination of resonance wavelength measurements and cavity ring-down spectroscopy is used to simultaneously determine the change in refractive index and the absorption induced by adsorption of ethylene diamine on a 300 μm silica sphere. A whispering gallery mode of the microsphere resonator is excited with intensity modulated light and the intensity and AM modulation phase of the Rayleigh backscattered light is measured. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE). DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7766e921-7cf2-4b99-9592-e281708eb812 ER - TY - JOUR TI - Cyclic dwell fatigue behaviour of single crystal Ni-base superalloys with/without rhenium AU - Yandt, S. AU - Wu, X.-J. AU - Tsuno, N. AU - Sato, A. T2 - Proceedings of the International Symposium on Superalloys T3 - 12th International Symposium on Superalloys, Superalloys 2012, 9 September 2012 through 13 September 2012, Seven Springs, PA SN - 9780470943205 SP - 501 EP - 508 KW - Creep-fatigue KW - Cyclic stress-strain behavior KW - Fatigue experiments KW - Isotropic coarsening KW - Low cycle fatigues KW - Microstructural analysis KW - Ni-base superalloys KW - Second generation KW - Fatigue of materials KW - Nickel KW - Single crystals KW - Superalloys AB - In this study, compressive dwell (C-D) and no-dwell (N-D) low-cycle fatigue (LCF) behaviours of several single crystal Ni-base superalloys, including CMSX-4, LSC-11 and LSC-15, were studied under strain-controlled zero-compression (RE = -co) loading at 1100°C. LSC-11 and LSC-15 are new alloys developed by 1H1 Corporation, Japan with 0.8 wt% Re and without Re addition, respectively, as reduced-cost alternatives to the second generation single crystal Ni-base superalloys. The fatigue experiments were conducted with or without a two-minute dwell (hold) in compression and total strain ranges of 0.7%, 0.6% and 0.5% on uncoated specimens in the [001] orientation. Examination of the cyclic stress-strain behavior revealed that the initially compressive mean stress relaxed to approximately zero stress in N-D tests, while compressive hold resulted in the development of a tensile mean stress during C-D fatigue. Cyclic stress softening was observed under all test conditions. Microstructural analysis of tested specimens showed that N-D fatigue promoted isotropic coarsening of the γ′ precipitates, while C-D loading resulted in the formation of discontinuous γ′ rafting parallel to the loading direction. Fatigue cracks initiated from the specimen surface from regions of localized oxide attack. All alloys were compressive dwell sensitive. C-D fatigue lives were 4-15× shorter than N-D when the same alloys were considered. CMSX-4 exhibited 1.5-3× N-D fatigue life advantage over alloys LSC-11 and LSC-15. Under C-D fatigue the life advantage of CMSX-4 was 20-50% greater than alloys LSC-11 and LSC-15. The differences in these behaviours could be attributed to Re content and oxidation. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0a71b1a9-c409-440a-8204-04a94a644319 ER - TY - JOUR TI - Attosecond pulse trains generated with oriented molecules DO - 10.1364/QELS.2012.QTu1C.4 AU - Frumker, Eugene AU - Kajumba, Nathaniel AU - Bertrand, Julien AU - Worner, Hans AU - Hebeisen, Christoph AU - Hockett, Paul AU - Spanner, Michael AU - Patchkovskii, Serguei AU - Paulus, Gerhard AU - Villeneuve, David M. AU - Corkum, Paul B. T2 - 2012 Conference on Lasers and Electro-Optics. CLEO 2012 T3 - 2012 Conference on Lasers and Electro-Optics, CLEO 2012, May 6-11, 2012, San Jose, CA, USA SN - 9781467318396 SP - 6327046 KW - Attosecond pulse trains KW - Attoseconds KW - Electronic asymmetry KW - Gasphase KW - High harmonics KW - Polar molecules KW - Sensitive probe KW - Lasers KW - Molecules AB - We report the measurement of high harmonics from oriented molecules in the gas phase. We show that attosecond and re-collision science provides a detailed and sensitive probe of electronic asymmetry in polar molecules. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 28f6013c-cb18-4faa-b335-8be525613a21 ER - TY - JOUR TI - Aggregation and privacy in multi-relational databases DO - 10.1109/PST.2012.6297921 AU - Jafer, Y. AU - Viktor, H. L. AU - Paquet, E. T2 - Privacy, Security and Trust (PST), 2012 Tenth Annual International Conference on T3 - 2012 10th Annual International Conference on Privacy, Security and Trust, PST 2012, July 16-18 2012, Paris, France SN - 9781467323260 SN - 9781467323239 SP - 6297921 SP - 67 EP - 74 KW - Aggregation functions KW - Data mining techniques KW - Predictive models KW - Privacy breaches KW - Privacy information KW - Privacy preserving data mining KW - Privacy violation KW - Relational Database KW - Aggregates KW - Data mining KW - Database systems KW - Data privacy AB - The aim of privacy-preserving data mining is to construct highly accurate predictive models while not disclosing privacy information. Aggregation functions, such as sum and count are often used to pre-process the data prior to applying data mining techniques to relational databases. Often, it is implicitly assumed that the aggregated (or summarized) data are less likely to lead to privacy violations during data mining. This paper investigates this claim, within the relational database domain. We introduce the PBIRD (Privacy Breach Investigation in Relational Databases) methodology. Our experimental results show that aggregation potentially introduces new privacy violations. That is, potentially harmful attributes obtained with aggregation are often different from the ones obtained from non-aggregated databases. This indicates that, even when privacy is enforced on non-aggregated data, it is not automatically enforced on the corresponding aggregated data. Consequently, special care should be taken during model building in order to fully enforce privacy when the data are aggregated. © 2012 IEEE. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 26be441a-9b02-480f-b4a4-abd515d28095 ER - TY - BOOK TI - Photonic sensing: principles and applications for safety and security monitoring DO - 10.1002/9781118310212 AU - Xiao, Gaozhi AU - Bock, Wojtek J. T2 - Wiley Series in Microwave and Optical Engineering SN - 9781118310212 SN - 9780470626955 SN - 047062695X AB - A cutting-edge look at safety and security applications of photonic sensors. With its many superior qualities, photonic sensing technology is increasingly used in early-detection and early-warning systems for biological hazards, structural flaws, and security threats. Photonic Sensing provides for the first time a comprehensive review of this exciting and rapidly evolving field, focusing on the development of cutting-edge applications in diverse areas of safety and security, from biodetection to biometrics. The book brings together contributions from leading experts in the field, fostering effective solutions for the development of specialized materials, novel optical devices, and networking algorithms and platforms. A number of specific areas of safety and security monitoring are covered, including background information, operation principles, analytical techniques, and applications. Topics include: Document security and structural integrity monitoring, as well as the detection of food pathogens and bacteria Surface plasmon sensors, micro-based cytometry, optofluidic techniques, and optical coherence tomography Optic fiber sensors for explosive detection and photonic liquid crystal fiber sensors for security monitoring Photonics-assisted frequency measurement with promising electronic warfare applications An invaluable, multidisciplinary resource for researchers and professionals in photonic sensing, as well as safety and security monitoring, this book will help readers jump-start their own research and development in areas of physics, chemistry, biology, medicine, mechanics, electronics, and defense. DA - 2012/09/18 PY - 2012 PB - Wiley LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9c22e57e-c07a-496d-8bb5-8fdb960ece01 ER - TY - BOOK TI - Electrochemical Technologies for Energy Storage and Conversion: volume 1 & 2 DO - 10.1002/9783527639496 AU - Liu, Ru-Shi AU - Zhang, Lei AU - Sun, Xueliang AU - Liu, Hansan AU - Zhang, Jiujun SN - 9783527639496 SN - 9783527328697 AB - In this handbook and ready reference, editors and authors from academia and industry share their in-depth knowledge of known and novel materials, devices and technologies with the reader. The result is a comprehensive overview of electrochemical energy and conversion methods, including batteries, fuel cells, supercapacitors, hydrogen generation and storage as well as solar energy conversion. Each chapter addresses electrochemical processes, materials, components, degradation mechanisms, device assembly and manufacturing, while also discussing the challenges and perspectives for each energy storage device in question. In addition, two introductory chapters acquaint readers with the fundamentals of energy storage and conversion, and with the general engineering aspects of electrochemical devices. With its uniformly structured, self-contained chapters, this is ideal reading for entrants to the field as well as experienced researchers. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA. DA - 2012/01/10 PY - 2012 PB - Wiley LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 200d3da1-bb15-44a7-8f72-4ed4155765b8 ER - TY - JOUR TI - Low-cost and high-efficient W-band substrate integrated waveguide antenna array made of printed circuit board process DO - 10.1109/TAP.2011.2180346 AU - Ghassemi, Nasser AU - Wu, Ke AU - Claude, Stephane AU - Zhang, Xiupu AU - Bornemann, Jens T2 - Transactions on Antennas and Propagation SN - 0018-926X SN - 1558-2221 VL - 60 IS - 3 SP - 1648 EP - 1653 KW - Antenna array; W-band antenna; Yagi-like antenna; substrate integrated waveguide (SIW) AB - A novel class of low-cost, small-footprint and high-gain antenna arrays is presented for W-band applications. A 4 × 4 antenna array is proposed and demonstrated using substrate-integrated waveguide (SIW) technology for the design of its feed network and longitudinal slots in the SIW top metallic surface to drive the array antenna elements. Dielectric cubes of low-permittivity material are placed on top of each 1 × 4 antenna array to increase the gain of the circular patch antenna elements. This new design is compared to a second 4 × 4 antenna array which, instead of dielectric cubes, uses vertically stacked Yagi-like parasitic director elements to increase the gain. Measured impedance bandwidths of the two 4 × 4 antenna arrays are about 7.5 GHz (94.2-101.8 GHz) at 18 ± 1 dB gain level, with radiation patterns and gains of the two arrays remaining nearly constant over this bandwidth. While the fabrication effort of the new array involving dielectric cubes is significantly reduced, its measured radiation efficiency of 81 percent is slightly lower compared to 90 percent of the Yagi-like design. DA - 2012/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f791ca9b-9109-4721-b1da-1feb3790e05e ER - TY - JOUR TI - Assessment of scavenge efficiency for a helicopter particle separation system DO - 10.4050/JAHS.57.022007 AU - Jiang, L. Y. AU - Benner, M. AU - Bird, J. T2 - Journal of the American Helicopter Society SN - 2161-6027 VL - 57 IS - 2 SP - 41 EP - 48 AB - The effectiveness of a helicopter particle separation system has been numerically assessed at practical operating conditions and sand environments for various scenarios. The particle separation mechanism and its limitations are revealed by the predicted flow field characteristics and particle trajectories. The separation-by-inertia concept is effective for removing large particles, but problematic for small particles of diameter ≤36 μm for the configuration and operating conditions considered in the present study. It is also found that particle size, shape factor, and rebound characteristics exert substantial effects on particle scavenge efficiency. However, the effects of gravity, particle inlet velocity, inlet mass distribution, and engine-operating conditions on scavenge efficiency are minor or limited. Finally, a few suggestions for further investigation on engine particle separation systems are included. DA - 2012/04/01 PY - 2012 PB - AHS International LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b2b2babf-5ffc-4648-bb8c-5e3f312512ec ER - TY - JOUR TI - Screening of pancreatic lipase and α-glucosidase inhibitors from Chinese dietary herbs DO - 10.4268/cjcmm20120931 AU - Xiaoli, Sun AU - Zhang, Kaibin AU - Ji, Xiuhong AU - Wang, Yanwen AU - Zidichouski, Jeffrey AU - Tong, Yan AU - Gao, Huimin AU - Zhang, Junzeng AU - Wang, Zhimin T2 - China Journal of Chinese Materia Medica SN - 1001-5302 VL - 37 IS - 9 SP - 1319 EP - 1323 KW - lipase inhibitor; α-glucosidase inhibitor; Chinese dietary herbs; screening AB - The present study was conducted to develop new inhibitors of pancreatic lipase and α-glucosidase from Chinese dietary herbs. Sixty-three dietary herbs from 39 taxonomic families were selected and extracted with aqueous ethanol or water. The extracts were then tested with in vitro enzyme assays for their ability to inhibit pancreatic lipase and α-glucosidase activities. Orlistat and acarbose were used as two positive controls. The extracts of Nelumbo nucifera, Curcuma longa, Piper longum and Morus alba showed strong pancreatic lipase inhibitory effects with IC50 at (28.00±5.51), (5.24±0.51), (14.76±2.58), (4.78±0.58), (3.41±0.67) mg·L-1, respectively. These extracts also showed potent α-glucosidase inhibitory activities with IC50 at (1.98±0.13), (0.18±0.007), (0.71±0.08), (0.077±0.005), (0.089±0.006) g·L-1, respectively. The results provide useful information for developing new drugs or natural health products for hyperlipidemia and hypoglycemia from Chinese dietary herbs. DA - 2012/05/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 11c8eb5a-5821-480a-9869-80f2ef79d244 ER - TY - JOUR TI - Wind tunnel and track tests of class 8 tractors pulling single and tandem trailers fitted with side skirts and boat-tails DO - 10.4271/2012-01-0104 AU - Cooper, Kevin R. T2 - SAE International Journal of Commercial Vehicles T3 - SAE 2012 World Congress & Exhibition, April 24-26, 2012, Detroit, Michigan, USA VL - 5 IS - 1 SP - 1 EP - 17 KW - Fuel Consumption; Aerodynamics; Heavy trucks AB - A 1:10-scale wind tunnel development program was undertaken by the National Research Council of Canada and Airshield Inc. in 1994 to develop trailer side skirts that would reduce the aerodynamic drag of single and tandem trailers. Additionally, a second wind tunnel program was performed by the NRC to evaluate the fuel-saving performance of boat-tail panels when used in conjunction with the skirt-equipped single and tandem trailers. Side skirts on tandem, 8.2-m-long trailers (all model dimensions converted to full scale) were found to reduce the wind-averaged drag coefficient at 105 km/h (65 mi/h) by 0.0758. The front pair of skirts alone produced 75% of the total drag reduction from both sets of skirts and the rear pair alone produced 40% of that from both pairs. The sum of the drag reductions from front and rear skirts separately was 115% of that when both sets were fitted, suggesting an interaction between both. The reductions in wind-averaged drag coefficient for single trailers with skirts only were 0.0524 for the 14.6-m trailer and 0.0406 for the 16.2-m single trailer. The data are quoted for skirt ground clearances of 305 mm (12 in.). The 0.50-m-long boat-tail panels combined with the tandem-trailer skirts to increase the wind-averaged drag coefficient reduction to a total of 0.1177. Boat-tails combined with skirts on the single trailers also increased the wind-averaged drag coefficient reductions to totals of 0.1051 and 0.0979 for the 14.6 m and 16.2 m trailers, respectively. Each boat-tail assembly consisted of angled panels attached to the top and the side rear edges of a trailer. The boat-tail panels on the single trailers and the rear trailer of the tandem pair were set at the optimum angle of 15°. The boat-tail panels on the front trailer of the tandem pair were set at 0°. Skirts were predicted to provide fuel savings for the tandem trailers at 105 km/h of 3.79 liters per hundred kilometers (L/(100 km)) (1.61 US gallons per 100 miles - US gal/(100 mi)) and 2.18 L/(100 km) (0.93 US gal/(100 mi)) and of 1.95 L/(100 km) (0.83 US gal/(100 mi)) for the 14.6-m and 16.2-m single trailers, respectively. It is not known why the longer trailer had the smaller fuel saving. The addition of boat-tail panels increased the predicted fuel savings for the skirt-equipped tandem trailers to 5.88 L/(100 km) (2.50 US gal/(100 mi)) and increased the fuel savings of the 14.6 m and 16.2 m single, skirt-equipped trailers to 5.25 L/(100 km) (2.23 US gal/(100 mi)) and to 4.89 L/(100 km) (2.08 US gal/(100 mi)), respectively. Track tests were undertaken using 8.2-m-long, skirt-equipped tandem trailers to verify the fuel-saving predictions based on the wind tunnel drag data. The boat-tails were not track tested. The track tests were performed by the staff at the Goodyear Proving Grounds in San Angelo, Texas. They demonstrated that skirts provided fuel savings of from 0.86 L/(100 km) to 3.54 L/(100 km), with the largest savings in the strongest side winds. The average track-test fuel saving measured over all runs was 2.29 L/(100 km) at an average road speed of 88 km/h. The average wind-tunnel-based prediction for these track runs was 2.25 L/(100 km), using a wind-averaged drag coefficient calculated for the wind conditions of each run. This was within one percent of the average of the track measurements. The wind speeds during the track tests were generally lower than the national average 11.3 km/h wind at truck mid height, averaging only 8 km/h. This indicated that the average fuel saving on the track was less than would be expected annually in North America. The track-test results confirmed the fuel-saving potential of skirts and demonstrated the reliability of fuel-saving predictions made from high-quality wind tunnel data. This correlation was only possible because the track-side winds were measured during each run. DA - 2012/04/16 PY - 2012 PB - SAE International LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3f5a5533-59f8-4686-ae03-7f8a527af133 ER - TY - JOUR TI - Hot forming of 7075 aluminium alloy tubes to produce complex and strong components DO - 10.4271/2012-01-0539 AU - Béland, Jean-François AU - D'Amours, Guillaume T2 - SAE Technical Papers; no. 2012-01-0539 T3 - SAE 2012 World Congress & Exhibition, April 24-26, 2012, Detroit, Michigan, USA AB - Lightweight tubular products offering enhanced stiffness and strength have always been of major concern for transportation and recreational applications. Hence, industries have turned to complex-shaped tubes to increase product performance and reduce energy costs. High-performance aluminum alloys, like 7075 for instance, have good mechanical properties such as high strength, but low formability at ambient temperature. Fortunately, hot tensile tests on 7075 samples have yielded an increase in formability with temperature. Therefore, testing has recently been launched at the Aluminum Technology Center to develop a new product application. More precisely, a 1,000-ton hydraulic press was equipped with +600°C heating plates and fitted with a bicycle handlebar mold. The plates provide 10 separate heating zones that can be adjusted independently. A thermo-mechanical model was also developed using LS-DYNA to determine tube temperatures around the heating zones. Hot tensile test results were also utilized to model tube behavior using an elastic viscoplastic temperature-dependent material constitutive law to predict tube wall stresses and strains. The finite element model can predict tube temperatures and gas pressures relative to time. Hot-forming process parameters were rapidly adjusted to successfully produce perfect handlebars. Conclusions not only include successful application where high formability is required, but also lead to a significant decrease in forming loads and lower tooling and mechanical energy costs. DA - 2012/04/16 PY - 2012 PB - SAE International LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1348c97e-a377-47cb-a101-5c3ac0f89f44 ER - TY - JOUR TI - Examination of the Maskell III blockage correction technique for full scale testing in the NRC 9-meter wind tunnel DO - 10.4271/2012-01-2047 AU - Leuschen, Jason AU - Mébarki, Youssef T2 - SAE International Journal of Commercial Vehicles T3 - SAE 2012 Commercial Vehicle Engineering Congress, October 2-3, 2012, Rosemont, Illinois, USA VL - 5 IS - 2 SP - 640 EP - 649 AB - The objective of this study was to assess the antimicrobial resistance and virulence genotypes of Enterococcus faecalis isolated from samples obtained from a commercial pork processing plant. A total of 200 samples were randomly obtained from carcasses after bleeding (BC; 50 samples) and pasteurization (PC; 100 samples) and from retail pork products (RP; 50 samples). One isolate from each E. faecalis –positive sample was analyzed for antimicrobial susceptibility and characterized using a enterococcal microarray for analysis of resistance and virulence genes. E. faecalis was isolated from 79.5% of BC samples, 2% of PC samples, and 72.7% of RP samples. Resistance to the clinically important drugs ciprofloxacin (one isolate each from BC and RP samples) and daptomycin (one isolate each from PC and RP samples) was found. Multiresistance (to five or more antimicrobials) was more common in E. faecalis isolates from BC (77.4% of isolates) samples than those from PC (25%) and RP (37.6%) samples. Resistance to kanamycin (43.5%) and streptomycin (69.2%) was noted mostly in E. faecalis from BC samples. The most common resistance genes (>5% prevalence) found in E. faecalis were those for aminoglycosides (aac(6), aphA3, and aadE), macrolides-lincosamide (ermB, ermA, sat(4), and linB), and tetracyclines (tetL, tetM, and tetO ). The virulence genes expressing adhesion (ace, efaAfs, and agrBfs), gelatinase (gelE), and pheromone (cAM, ccF10, cob, and cpd1) factors were found in the majority of isolates. Significant associations were found between resistance and virulence genes, suggesting their possible relationship. These data suggest that carcasses entering the final product processing area are mostly free of E. faecalis but are recontaminated with antimicrobial-resistant strains during processing. The source of these contaminants remains to be identified; however, these results underscore the importance of E. faecalis as a reservoir of resistance and virulence genes. DA - 2012/09/24 PY - 2012 PB - SAE International LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 25c809ee-3468-4529-8360-886d828cf7ca ER - TY - JOUR TI - Characterization of antimicrobial resistance and virulence genotypes of Enterococcus faecalis recovered from a pork processing plant DO - 10.4315/0362-028X.JFP-11-524 AU - Aslam, Mueen AU - Diarra, Moussa S. AU - Masson, Luke T2 - Journal of Food Protection SN - 0362-028X VL - 75 IS - 8 SP - 1486 EP - 1491 AB - The objective of this study was to assess the antimicrobial resistance and virulence genotypes of Enterococcus faecalis isolated from samples obtained from a commercial pork processing plant. A total of 200 samples were randomly obtained from carcasses after bleeding (BC; 50 samples) and pasteurization (PC; 100 samples) and from retail pork products (RP; 50 samples). One isolate from each E. faecalis –positive sample was analyzed for antimicrobial susceptibility and characterized using a enterococcal microarray for analysis of resistance and virulence genes. E. faecalis was isolated from 79.5% of BC samples, 2% of PC samples, and 72.7% of RP samples. Resistance to the clinically important drugs ciprofloxacin (one isolate each from BC and RP samples) and daptomycin (one isolate each from PC and RP samples) was found. Multiresistance (to five or more antimicrobials) was more common in E. faecalis isolates from BC (77.4% of isolates) samples than those from PC (25%) and RP (37.6%) samples. Resistance to kanamycin (43.5%) and streptomycin (69.2%) was noted mostly in E. faecalis from BC samples. The most common resistance genes (>5% prevalence) found in E. faecalis were those for aminoglycosides (aac(6), aphA3, and aadE), macrolides-lincosamide (ermB, ermA, sat(4), and linB), and tetracyclines (tetL, tetM, and tetO ). The virulence genes expressing adhesion (ace, efaAfs, and agrBfs), gelatinase (gelE), and pheromone (cAM, ccF10, cob, and cpd1) factors were found in the majority of isolates. Significant associations were found between resistance and virulence genes, suggesting their possible relationship. These data suggest that carcasses entering the final product processing area are mostly free of E. faecalis but are recontaminated with antimicrobial-resistant strains during processing. The source of these contaminants remains to be identified; however, these results underscore the importance of E. faecalis as a reservoir of resistance and virulence genes. DA - 2012/08/01 PY - 2012 PB - International Association for Food Protection LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 233f0b9b-ba6a-4bee-bba6-9aaffd1644a0 ER - TY - JOUR TI - Immunomagnetic capture of Bacillus anthracis spores from food DO - 10.4315/0362-028X.JFP-12-048 AU - Shields, Michael J. AU - Hahn, Kristen R. AU - Janzen, Timothy W. AU - Goji, Noriko AU - Thomas, Matthew C. AU - Kingombe, Cesar Bin I. AU - Paquet, Chantal AU - Kell, Arnold J. AU - Amoako, Kingsley K. T2 - Journal of Food Protection SN - 0362-028X VL - 75 IS - 7 SP - 1243 EP - 1248 AB - Food is a vulnerable target for potential bioterrorist attacks; therefore, a critical mitigation strategy is needed for the rapid concentration and detection of biothreat agents from food matrices. Magnetic beads offer a unique advantage in that they have a large surface area for efficient capture of bacteria. We have demonstrated the efficient capture and concentration of Bacillus anthracis (Sterne) spores using immunomagnetic beads for a potential food application. Magnetic beads from three different sources, with varying sizes and surface chemistries, were functionalized with monoclonal antibodies and polyclonal antibodies from commercial sources and used to capture and concentrate anthrax spores from spiked food matrices, including milk, apple juice, bagged salad, processed meat, and bottled water. The results indicated that the Pathatrix beads were more effective in the binding and capture of anthrax spores than the other two bead types investigated. Furthermore, it was observed that the use of polyclonal antibodies resulted in a more efficient recovery of anthrax spores than the use of monoclonal antibodies. Three different magnetic capture methods, inversion, the Pathatrix Auto system, and the new i CropTheBug system, were investigated. The i CropTheBug system yielded a much higher recovery of spores than the Pathatrix Auto system. Spore recoveries ranged from 80 to 100% for the i CropTheBug system when using pure spore preparations, whereas the Pathatrix Auto system had recoveries from 20 to 30%. Spore capture from food samples inoculated at a level of 1 CFU/ml resulted in 80 to 100% capture for milk, bottled water, and juice samples and 60 to 80% for processed meat and bagged salad when using the i CropTheBug system. This efficient capture of anthrax spores at very low concentrations without enrichment has the potential to enhance the sensitivity of downstream detection technologies and will be a useful method in a foodborne bioterrorism response. DA - 2012/07/01 PY - 2012 PB - International Association for Food Protection LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1f4bf0d6-621c-45a4-afff-de8c851157bd ER - TY - JOUR TI - Metallic under-layer coating as third line of protection of underground oil and gas pipelines from external corrosion DO - 10.5006/0566 AU - Papavinasam, S. AU - Arsenault, B. AU - Attard, M. AU - Revie, R. W. T2 - Corrosion SN - 0010-9312 VL - 68 IS - 12 SP - 1146 EP - 1153 KW - cathodic protection, external corrosion, metallic under-layer coating, oil and gas pipelines, polymeric coating AB - This paper presents the concept of introducing a third line of defense in the form of a metallic under-layer coating—in addition to the traditional polymeric coating and applied cathodic protection (CP)—to protect the external surface of oil and gas pipelines. The three levels of protection would be the metallic under-layer coating, the polymeric top-layer coating, and the applied CP. This three-level system would be beneficial when the applied CP current is shielded from the pipeline by a dis-bonded polymeric coating, thermal insulator, or highly resistive soil. Two different combinations of metallic under-layer and polymeric top-layer coatings are presented to demonstrate this concept: 48%Zn and 52%Al under-layer with four different top-layer coatings: fusion-bonded epoxy (FBE), composite, urethane, and coal tar epoxy. Urethane top-layer coating with four different metallic under-layers: 48%Zn-52%Al, 85%Zn-15%Al, Al, and Zn. The criteria for the successful application of this concept also have been described. DA - 2012/07/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 67e551b5-8a8b-44d1-a853-c8a04afa514d ER - TY - JOUR TI - Economic-based modelling for resource scheduling in grid computing DO - 10.1109/CSCWD.2012.6221877 AU - Aburukba, Raafat AU - Ghenniwa, Hamada AU - Shen, Weiming T2 - Proceedings of the 2012 IEEE 16th International Conference on Computer Supported Cooperative Work in Design (CSCWD): May 23-25, 2012, Wuhan, China T3 - 2012 IEEE 16th International Conference on Computer Supported Cooperative Work in Design (CSCWD), 23-25 May 2012, Wuhan, China SN - 978-1-4673-1212-7 SN - 978-1-4673-1211-0 SN - 978-1-4673-1210-3 SP - 583 EP - 590 KW - Agent oriented; Grid bidding language; Grid computing; decentralized scheduling; economic-based approach AB - In decentralized computational environments applications or services belong to different organizations with different objectives. Grid computing model is appropriate for such environments, in particular for large scale computations. In this paper, decentralization is modeled in terms self-interested, economically inspired agents that attempt to achieve their goals. The objective of this work is to model the Grid scheduling problem based on the nature of the Grid environment and the characteristics of the Grid entities focusing on the resource utilization and completion time objectives. We create a mapping between the Grid scheduling problem and the combinatorial allocation problem and propose an adequate economic-based optimization model and a bidding language for the Grid scheduling problem. The proposed approach is being validated through a prototype implementation using the Coordinated Intelligent Rational Agent (CIR-Agent) model. DA - 2012/05 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ac7b64da-9ae1-4c27-b3e0-67fc4d8a40de ER - TY - JOUR TI - On the molar mass of silicon for a new Avogadro constant DO - 10.1109/CPEM.2012.6251010 AU - Meija, J. AU - Mester, Z. AU - Pramann, A. AU - Rabb, S. AU - Rienitz, O. AU - Schiel, D. AU - Sturgeon, R. AU - Turk, G. AU - Vocke, R. AU - Yang, L. T2 - 2012 Conference on Precision Electromagnetic Measurements (CPEM 2012) T2 - CPEM Digest T3 - 2012 Conference on Precision Electromagnetic Measurements (CPEM 2012), July 1-6, 2012, Washington, DC, USA SN - 0589-1485 SN - 978-1-4673-0442-9 SN - 978-1-4673-0441-2 SP - 476 EP - 477 KW - Avogadro constant; isotope dilution mass spectrometry; molar mass; multicollector ICP-mass spectrometry; silicon; uncertainty AB - An overview of the present results and status of the molar mass of a silicon crystal highly enriched in ²⁸Si used for a new determination of the Avogadro constant is given with special emphasis on the cooperation between NIST, NRC, and PTB currently working on this topic. Using an experimental combination of multicollector ICP and isotope dilution mass spectrometry, a new approach developed by PTB for the measurement of the isotopic composition has been applied. It focuses on the isotope ratio treatment of ³°Si/²⁹Si mainly, avoiding the more uncertain measurement of ratios related to the main isotope ²⁸Si. DA - 2012 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 633fa62c-621a-4b2d-b0e7-d93adac19ff6 ER - TY - JOUR TI - Membrane raft disruption results in neuritic retraction prior to neuronal death in cortical neurons DO - 10.5582/bst.2012.v6.4.183 AU - Whitehead, S. N. AU - Gangaraju, S. AU - Aylsworth, A. AU - Hou, S. T. T2 - BioScience Trends VL - 6 IS - 4 SP - 183 EP - 191 AB - Membrane rafts, rich in sphingolipids and cholesterol, play an important role in neuronal membrane domain-specific signaling events, maintaining synapses and dendritic spines. The purpose of this study is to examine the neuronal response to membrane raft disruption. Membrane rafts of 8 DIV primary neuronal cultures were isolated based on the resistance to Triton X-100 and ability to float in sucrose gradients. Membrane rafts from primary cortical neurons were also imaged using the membrane raft marker, cholera toxin subunit-B (CTxB), and were co-immunolabelled with the dendritic microtubule associated protein marker, MAP-2, the dendritic and axonal microtubule protein, β-III-Tubulin, and the axonal microtubule protein, Tau. Exposure of cortical neurons to either the cholesterol depleting compound, methyl-beta-cyclodextrin (MBC), or to the glycosphingolipid metabolism inhibiting agent D-threo-1-phenyl-2-decanoylamino-3- morpholino-1-propanol (D-PDMP), resulted in neuritic retraction prior to the appearance of neuronal death. Further investigation into the effects of MBC revealed a pronounced perturbation of microtubule protein association with membrane rafts during neuritic retraction. Interestingly, stabilizing microtubules with Paclitaxel did not prevent MBC induced neuritic retraction, suggesting that neuritic retraction occurred independently of microtubule disassembly and that microtubule association with membrane rafts is critical for maintaining neuritic stability. Overall, the data indicated that membrane rafts play an important role in neurite stability and neuronal viability. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c7c81d82-4789-413b-80d0-47c989c51355 ER - TY - JOUR TI - In-flight icing of UAVs: the influence of flight speed coupled with chord size DO - 10.5589/q12-007 AU - Szilder, Krzysztof AU - McIlwain, Stuart T2 - Canadian Aeronautics Space Journal SN - 0010-9312 VL - 58 IS - 2 SP - 83 EP - 94 AB - The intensive deployment of unmanned aerial vehicles (UAVs) for surveillance and reconnaissance missions during the last couple of decades has revealed their vulnerability to icing conditions. At present, a common icing avoidance strategy is simply not to fly when icing is forecast. Consequently, UAV missions in cold seasons and cold regions can be delayed for days when icing conditions persist. While this approach limits substantially the failure of UAV missions as a result of icing, there is obviously a need to develop all-weather capabilities. A key step in accomplishing this objective is to understand better the influence of a smaller geometry and a lower speed on the ice accretion process, relative to the extensively researched area of in-flight icing for traditional aircraft configurations characterized by high Reynolds number. Our analysis of the influence of Reynolds number on the ice accretion process is performed for the NACA0012 airfoil. Analytical analysis of the integrated mass and energy balance equations along the airfoil surface allows the identification of regimes of rime and glaze formation, as well as the ice accretion extent as a function of static air temperature and liquid water content. For each Reynolds number, a Computational Fluid Dynamics solver computes the airflow field and the distributions of Stanton number and static air pressure along the airfoil surface. Next, a drop trajectory solver computes the distribution of collection efficiency along the airfoil for a given drop size. Finally, a morphogenetic model is used to predict the ice accretion shape and its extent over the entire Reynolds number range under consideration. Our analysis highlights the differences between ice accretions on components of traditional aircraft and UAVs, arising from their differences in cruising speed and airfoil dimensions. DA - 2012/07/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3f2156d5-1e5e-46ce-8a51-93e4730539a5 ER - TY - JOUR TI - Development of the shock simulation methodology for spacecraft components DO - 10.5589/q12-009 AU - Nejad Ensan, M. AU - Zimcik, D. G. T2 - Canadian Aeronautics Space Journal SN - 0010-9312 VL - 58 IS - 2 SP - 105 EP - 114 AB - Spacecraft components encounter mechanical shock from a variety of sources. Components must withstand a series of flight shock pulses and must be designed and tested accordingly to ensure reliability. This paper presents a “Design for Shock” methodology to accurately analyze the response to shock for components under the short duration dynamic loading to assess component structural integrity and demonstrate design robustness. This methodology uses a more realistic simulation of the response of the component to shock loading using a wave propagation solution based on explicit time integration of the transient shock event rather than a stationary random and (or) quasi-static approach which has been traditionally used for this analysis. This approach was applied to a sensitive scientific instrument to demonstrate its effectiveness. The method is shown to provide a more accurate simulation of the shock event thereby reducing the unknown conservatism of the stationary random and (or) quasi-static approach while providing accurate simulation of the transient dynamic response of the structure. DA - 2012/07/27 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f917b846-caf5-434e-a6ca-059636310179 ER - TY - JOUR TI - Erosion-corrosion assessment of tungsten carbide-based plasma-tranferred arc-welded overlays DO - 10.5006/1.3683231 AU - Jones, M. AU - Llewellyn, R. J. T2 - Corrosion SN - 0010-9312 VL - 68 IS - 2 SP - 026003-1 EP - 026003-14 AB - Two commercially available tungsten carbide-based, Ni alloy binder plasma-transferred arc-welded (PTAW) overlays, which had both previously exhibited excellent resistance to slurry erosion (in substantially non-corrosive conditions) and abrasion, were assessed in a more corrosive slurry erosion environment. One overlay consisted of a 50 vol% mixture of crushed eutectic (WC/W2C), spherical eutectic, and tungsten monocarbide (WC) particles in a NiBSi matrix, while the other contained 50 vol% WC in a NiCrBSi matrix. Initial microstructural examination of the mixed carbide/NiBSi overlay confirmed that substantial dissolution/degradation of the spherical eutectic and crushed eutectic carbides had occurred as a consequence of interaction with its matrix alloy constituent at the high temperatures encountered during arc deposition. Conversely, the WC-based overlay exhibited very limited carbide dissolution or degradation. The total erosion-corrosion (E-C) rate, as well as its separate components, namely, erosion, corrosion, and synergy, was established using a novel slurry pot erosion-corrosion (SPEC) tester. The E-C rate for the WC/NiCrBSi overlay was approximately four times less than the E-C rate for the mixed carbide/NiBSi overlay, which performed comparatively poorly. The mixed carbide/NiBSi overlay displayed a very large synergistic value, which accounted for 90% of the total erosion-corrosion rate, with the WC/NiCrBSi showing a synergy level accounting for 50% of the total E-C rate. To establish and compare the damage mechanisms affecting both overlays, a novel technique was implemented where specific regions were examined using scanning electron microscopy (SEM) before and after SPEC testing. This procedure was applied to identify any preferential attack that was occurring and to elucidate the reasons for the significantly different E-C performance of the two products. The main reasons for the inferior performance of the mixed carbide/NiBSi overlay were found to be caused by the attack of the non-Cr bearing matrix and preferential removal of the W/Ni-rich boundary layer and eta-carbides, formed around the eutectic carbides during deposition. DA - 2012/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3b2a59a7-3140-435d-98f9-bbeb31629b26 ER - TY - JOUR TI - Isolation, identification and characterization of a antidementia acetylcholinesterase inhibitor-producing Yarrowia lipolytica S-3 DO - 10.5941/MYCO.2012.40.1.042 AU - Kang, Min-Gu AU - Yoon, Min-Ho AU - Choi, Young-Jun AU - Lee, Jong-Soo T2 - Mycobiology SN - 1229-8093 SN - 2092-9323 VL - 40 IS - 1 SP - 42 EP - 46 KW - Antidementia acetylcholinesterase inhibitor, Yarrowia lipolytica S-3, 26S rDNA sequences AB - This report describes the isolation and identification of a potent acetylcholinesterase (AChE) inhibitor-producing yeasts. Of 731 species of yeast strain, the S-3 strain was selected as a potent producer of AChE inhibitor. The selected S-3 strain was investigated for its microbiological characteristics. The S-3 strain was found to be short-oval yeast that did not form an ascospore. The strain formed a pseudomycelium and grew in yeast malt medium containing 50% glucose and 10% ethanol. Finally, the S-3 strain was identified by its physiological characteristics and 26S ribosomal DNA sequences as Yarrowia lipolytica S-3. DA - 2012/03/31 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3681db8d-d639-4fe8-afd6-dfe8e259634b ER - TY - JOUR TI - Nonlinear effects of carbon nanotube coated single mode optical fiber gratings DO - 10.7149/OPA.45.2.177 AU - Villanueva, Guillermo E. AU - Jakubinek, Michael B. AU - Simard, Benoit AU - Otón, Claudio J. AU - Shao, Li-Yang AU - Pérez-Millán, Pere AU - Albert, Jacques T2 - Óptica Pura y Aplicada SN - 21718814 SN - 00303917 VL - 45 IS - 2 SP - 177 EP - 182 KW - Fiber Bragg Grating, Non-Linear Materials, Fiber Devices AB - Single-wall carbon nanotube deposition on the cladding of optical fibers has been carried out to fabricate an all-fiber nonlinear device. Two different nanotube deposition techniques were studied. The first consisted of repeatedly immersing the optical fiber into a nanotube supension, increasing the thickness of the coating in each step. The second deposition involved wrapping a thin film of nanotubes around the optical fiber. For both cases, interaction of transmitted light through the fiber core with the external coating was assisted by the cladding mode resonances of a tilted fiber Bragg grating. Ultrafast nonlinear effects of the nanotube-coated fiber were measured by means of a pump- probe pulses experiment. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d5f8a10f-ebb2-45fb-b72e-a8822db49a1a ER - TY - JOUR TI - In-storage psychrophilic anaerobic digestion: acclimated microbial kinetics DO - 10.1080/09593330.2011.644867 AU - King, Susan AU - Courvoisier, Pierre AU - Guiot, Serge AU - Barrington, Suzelle T2 - Environmental Technology SN - 0959-3330 SN - 1479-487X VL - 33 IS - 15 SP - 1763 EP - 1772 KW - psychrophilic anaerobic digestion, specific substrate uptake, manure treatment, microbial kinetics, swine manure AB - In-storage psychrophilic anaerobic digestion develops by microbial acclimation in covered swine-manure storage tanks, producing CH4 and stabilizing organic matter. To optimize the system's performance, the process kinetics must be understood. The objective of this study was to evaluate kinetic parameters describing the major stages in the digestion process, and to investigate the effect of temperature acclimation on these parameters. Specific activity tests were performed using manure inocula and five substrates at three incubation temperatures. Extant substrate activities were determined analytically for each case, and intrinsic kinetic parameters for glucose uptake were estimated by grid search fitting to the Monod model. The results demonstrate that this acclimated microbial community exhibits different kinetic parameters to those of the mesophilic communities currently modelled in the literature, with increased activity at low temperatures, varying with substrate and temperature. For glucose, the higher uptake is accompanied by lower microbial yield and half-saturation constant. Decomposing these values suggests that active psychrophilic and mesophilic microbial populations co-exist within the community. This work also confirms that a new method of assessing microbial substrate kinetics must be developed for manure microbial communities, separating microbial mass from other suspended organics. DA - 2012/01/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ea0a3824-1f41-415d-9242-63a682772846 ER - TY - JOUR TI - Shaping polarization of attosecond pulses via laser control of electron and hole dynamics DO - 10.1080/09500340.2012.690051 AU - Morales, Felipe AU - Barth, Ingo AU - Serbinenko, Valeria AU - Patchkovskii, Serguei AU - Smirnova, Olga T2 - Journal of Modern Optics SN - 0950-0340 SN - 1362-3044 VL - 59 IS - 15 SP - 1303 EP - 1311 KW - attosecond science, high harmonic generation, attosecond pulses, polarization, nonlinear and ultrafast optics (inc. harmonic generation, multiphoton spectroscopy) AB - We show how laser control over both electronic and hole dynamics in aligned molecules can be used to shape polarization of attosecond pulses produced via high harmonic generation driven by two-color, linearly polarized laser fields. DA - 2012/09/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 069acb0f-d271-492d-8d3d-dbfbde8e9cda ER - TY - JOUR TI - Towards an understanding of the helium–acetylene van der Waals complex DO - 10.1080/00268976.2012.699108 AU - Rezaei, Mojtaba AU - Moazzen-Ahmadi, N. AU - McKellar, A. R. W. AU - Fernández, Berta AU - Farrelly, David T2 - Molecular Physics SN - 0026-8976 SN - 1362-3028 VL - 110 IS - 21-22 SP - 2743 EP - 2750 KW - helium, acetylene, dimer, spectroscopy, infrared, van der Waals AB - The weakly bound complex He–C2D2 is studied in the ν 3 fundamental band of C2D2 (≈2440 cm−¹) using a tuneable infrared diode laser to probe a pulsed supersonic slit jet expansion. This is the first published spectrum for helium–acetylene. Transitions observed in the region of the C2D2 R(0) line are assigned with the help of theoretical results based on an ab initio intermolecular potential, and fitted using a simple Coriolis model. The results indicate that the complex is rather close to the free rotor limit, helping to explain the absence of previous data. Scaled parameters from the model are used to predict a spectrum for He–C2H2. DA - 2012/06/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b0f849a8-6632-4493-b96e-3f2a10f3faf1 ER - TY - JOUR TI - On the assignment problem of arbitrary processing time operations in partially overlapping manufacturing resources DO - 10.1109/CoASE.2012.6386373 AU - Ghonaim, W. AU - Ghenniwa, H. AU - Shen, W. T2 - IEEE International Conference on Automation Science and Engineering (CASE), 2012 20-24 Aug. 2012, Seoul, Korea T3 - 2012 IEEE International Conference on Automation Science and Engineering (CASE 2012), 20-24 August 2012, Seoul, Korea (South) SN - 978-1-4673-0430-6 SN - 978-1-4673-0429-0 SN - 978-1-4673-0428-3 SP - 341 EP - 346 KW - job shop scheduling; machine tools; manufacturing resources planning; resource allocation AB - The frequent transfers' challenge of workpieces between multiple resources is quite evident in the production process of customized parts. In fact, special jobs' transfers and processing, often, require workpiece unloading, transport and loading with, rather, idling and reconfiguration of resources that impact much job completion time and resource utilization. The overlapping capabilities of machine tools, otherwise, are common with, typically, few special tooling. In such settings, the overlapping and special tooling capabilities intensify the complexity of the assignment problem, mainly, when allocating the operations of arbitrary processing times. This work targets the efficient assignment of unrelated jobs of operations with arbitrary processing time to multiple resources of partially overlapping capabilities. The work introduces a formal model and a more efficient solution approach for minimizing jobs' transfer and balancing workloads. The sequencing problem of the assigned unrelated jobs would be, then, an orthogonal problem, of less significance, that can be tackled separately. DA - 2012/12/24 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 894dc329-cb99-4959-9767-cbfae79fce92 ER - TY - JOUR TI - New spectroscopic results on acetylene dimers and trimers DO - 10.1080/00268976.2012.697588 AU - Oliaee, J. Norooz AU - Moazzen-Ahmadi, N. AU - McKellar, A. R. W. T2 - Molecular Physics SN - 0026-8976 SN - 1362-3028 VL - 110 IS - 21-22 SP - 2797 EP - 2805 KW - acetylene, dimer, trimer, cluster, spectroscopy, infrared, van der Waals AB - Spectra of acetylene dimers and trimers containing one or more C2D2 monomer are studied in the ν3 fundamental band region of C2D2 (≈2440 cm−¹) using a tuneable infrared diode laser to probe a pulsed supersonic slit jet expansion. Four new subbands are observed in the perpendicular band of (C2D2)2, and this enables the first direct determination of the A rotational constant for an acetylene dimer. The value found for A is significantly larger than the previous indirect value based on microwave spectra. The dimer parallel band is observed and found to be highly perturbed, and observations are extended for the mixed dimer C2D2 – C2H2. The trimers (C2D2)3, (C2D2)2 – C2H2, and C2D2 – (C2H2)2 are observed spectroscopically for the first time. Establishment of a precise band origin is difficult for (C2D2)3 because of the inherent nature of the spectrum, but this is possible for two out of three of the bands of the mixed trimers. DA - 2012/06/14 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 81cd5381-8300-4ff8-8a68-9b597f67f230 ER - TY - JOUR TI - Diversity in the protein N-glycosylation pathways within the Campylobacter genus DO - 10.1074/mcp.M112.021519 AU - Nothaft, Harald AU - Scott, Nichollas E. AU - Vinogradov, Evgeny AU - Liu, Xin AU - Hu, Rui AU - Beadle, Bernadette AU - Fodor, Christopher AU - Miller, Willian G. AU - Li, Jianjun AU - Cordwell, Stuart J. AU - Szymanski, Christine M. T2 - Molecular & Cellular Proteomics SN - 1535-9476 SN - 1535-9484 VL - 11 IS - 11 SP - 1203 EP - 1219 AB - The foodborne bacterial pathogen, Campylobacter jejuni, possesses an N-linked protein glycosylation (pgl) pathway involved in adding conserved heptasaccharides to asparagine-containing motifs of >60 proteins, and releasing the same glycan into its periplasm as free oligosaccharides. In this study, comparative genomics of all 30 fully sequenced Campylobacter taxa revealed conserved pgl gene clusters in all but one species. Structural, phylogenetic and immunological studies showed that the N-glycosylation systems can be divided into two major groups. Group I includes all thermotolerant taxa, capable of growth at the higher body temperatures of birds, and produce the C. jejuni-like glycans. Within group I, the niche-adapted C. lari subgroup contain the smallest genomes among the epsilonproteobacteria, and are unable to glucosylate their pgl pathway glycans potentially reminiscent of the glucosyltransferase regression observed in the O-glycosylation system of Neisseria species. The nonthermotolerant Campylobacters, which inhabit a variety of hosts and niches, comprise group II and produce an unexpected diversity of N-glycan structures varying in length and composition. This includes the human gut commensal, C. hominis, which produces at least four different N-glycan structures, akin to the surface carbohydrate diversity observed in the well-studied commensal, Bacteroides. Both group I and II glycans are immunogenic and cell surface exposed, making these structures attractive targets for vaccine design and diagnostics. DA - 2012/08/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 01f49d78-f3c4-4481-8679-7c620327137e ER - TY - JOUR TI - Domain organization of the polymerizing mannosyltransferases involved in synthesis of the Escherichia coli O8 and O9a lipopolysaccharide O-antigens DO - 10.1074/jbc.M112.412577 AU - Greenfield, Laura K. AU - Richards, Michele R. AU - Vinogradov, Evgeny AU - Wakarchuk, Warren W. AU - Lowary, Todd L. AU - Whitfield, Chris T2 - Journal of Biological Chemistry SN - 0021-9258 SN - 1083-351X VL - 287 IS - 45 SP - 38135 EP - 38149 KW - Bacteria; Biosynthesis; Glycoconjugate; Glycosyltransferases; Lipopolysaccharide (LPS); E. coli; O-polysaccharide; Mannosyltransferase; Modular Enzyme; Polymerase AB - The Escherichia coli O9a and O8 polymannose O-polysaccharides (O-PSs) serve as model systems for the biosynthesis of bacterial polysaccharides by ATP-binding cassette transporter-dependent pathways. Both O-PSs contain a conserved primer-adaptor domain at the reducing terminus and a serotype-specific repeat unit domain. The repeat unit domain is polymerized by the serotype-specific WbdA mannosyltransferase. In serotype O9a, WbdA is a bifunctional α-(1→2)-, α-(1→3)-mannosyltransferase, and its counterpart in serotype O8 is trifunctional (α-(1→2), α-(1→3), and β-(1→2)). Little is known about the detailed structures or mechanisms of action of the WbdA polymerases, and here we establish that they are multidomain enzymes. WbdA^O9a contains two separable and functionally active domains, whereas WbdA^O8 possesses three. In WbdC^O9a and WbdB^O9a, substitution of the first Glu of the EX7E motif had detrimental effects on the enzyme activity, whereas substitution of the second had no significant effect on activity in vivo. Mutation of the Glu residues in the EX7E motif of the N-terminal WbdA^O9a domain resulted in WbdA variants unable to synthesize O-PS. In contrast, mutation of the Glu residues in the motif of the C-terminal WbdA^O9a domain generated an enzyme capable of synthesizing an altered O-PS repeat unit consisting of only α-(1→2) linkages. In vitro assays with synthetic acceptors unequivocally confirmed that the N-terminal domain of WbdA^O9a possesses α-(1→2)-mannosyltransferase activity. Together, these studies form a framework for detailed structure-function studies on individual domains and a strategy applicable for dissection and analysis of other multidomain glycosyltransferases. DA - 2012/09/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a086cbd3-35a4-4fb8-ad2d-e2b05c1372cd ER - TY - JOUR TI - Biosynthesis of the polymannose lipopolysaccharide O-antigens from Escherichia coli serotypes O8 and O9a requires a unique combination of single- and multiple-active site mannosyltransferases DO - 10.1074/jbc.M112.401000 AU - Greenfield, Laura K. AU - Richards, Michele R. AU - Li, Jianjun AU - Wakarchuk, Warren W. AU - Lowary, Todd L. AU - Whitfield, Chris T2 - Journal of Biological Chemistry SN - 0021-9258 SN - 1083-351X VL - 287 IS - 42 SP - 35078 EP - 35091 KW - Cell Wall; Escherichia coli; Glycobiology' Glycoconjugate; Glycosyltransferases; Lipopolysaccharide (LPS); O-antigen; Bacterial Cell Envelope; Mannosyltransferases; Polysaccharides; O-polysaccharide; Glycan Synthesis AB - The Escherichia coli O9a and O8 O-antigen serotypes represent model systems for the ABC transporter-dependent synthesis of bacterial polysaccharides. The O9a and O8 antigens are linear mannose homopolymers containing conserved reducing termini (the primer-adaptor), a serotype-specific repeat unit domain, and a terminator. Synthesis of these glycans occurs on the polyisoprenoid lipid-linked primer, undecaprenol pyrophosphoryl-GlcpNAc, by two conserved mannosyltransferases, WbdC and WbdB, and a serotype-specific mannosyltransferase, WbdA. The glycan structure and pattern of conservation in the O9a and O8 mannosyltransferases are not consistent with the existing model of O9a biosynthesis. Here we establish a revised pathway using a combination of in vivo (mutant complementation) experiments and in vitro strategies with purified enzymes and synthetic acceptors. WbdC and WbdB synthesize the adaptor region, where they transfer one and two α-(1→3)-linked mannose residues, respectively. The WbdA enzymes are solely responsible for forming the repeat unit domains of these O-antigens. WbdA^O9a has two predicted active sites and polymerizes a tetrasaccharide repeat unit containing two α-(1→3)- and two α-(1→2)-linked mannopyranose residues. In contrast, WbdA^O8 polymerizes trisaccharide repeat units containing single α-(1→3)-, α-(1→2)-, and β-(1→2)-mannopyranoses. These studies illustrate assembly systems exploiting several mannosyltransferases with flexible active sites, arranged in single- and multiple-domain formats. DA - 2012/08/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bd5ea567-1a63-4674-8f4d-e7c312a1c6f0 ER - TY - JOUR TI - Enzymatic engineering of polysialic acid on cells in vitro and in vivo using a purified bacterial polysialyltransferase DO - 10.1074/jbc.M112.377614 AU - El Maarouf, Abderrahman AU - Moyo-Lee Yaw, Damali AU - Lindhout, Theresa AU - Pearse, Damien D. AU - Wakarchuk, Warren AU - Rutishauser, Urs T2 - Journal of Biological Chemistry SN - 0021-9258 SN - 1083-351X VL - 287 IS - 39 SP - 32770 EP - 32779 KW - Adhesion; Bioengineering; Glycobiology; Glycoprotein Biosynthesis; Glycosyltransferases; Cell Surface; Neuroplasticity; Polysialic Acid; Polysialyltransferase; Tissue Repair AB - In vertebrates, polysialic acid (PSA) is typically added to the neural cell adhesion molecule (NCAM) in the Golgi by PST or STX polysialyltransferase. PSA promotes plasticity, and its enhanced expression by viral delivery of the PST or STX gene has been shown to promote cellular processes that are useful for repair of the injured adult nervous system. Here we demonstrate a new strategy for PSA induction on cells involving addition of a purified polysialyltransferase from Neisseria meningitidis (PSTNm) to the extracellular environment. In the presence of its donor substrate (CMP-Neu5Ac), PSTNm synthesized PSA directly on surfaces of various cell types in culture, including Chinese hamster ovary cells, chicken DF1 fibroblasts, primary rat Schwann cells, and mouse embryonic stem cells. Similarly, injection of PSTNm and donor in vivo was able to produce PSA in different adult brain regions, including the cerebral cortex, striatum, and spinal cord. PSA synthesis by PSTNm requires the presence of the donor CMP-Neu5Ac, and the product could be degraded by the PSA-specific endoneuraminidase-N. Although PSTNm was able to add PSA to NCAM, most of its product was attached to other cell surface proteins. Nevertheless, the PSTNm-induced PSA displayed the ability to attenuate cell adhesion, promote neurite outgrowth, and enhance cell migration as has been reported for endogenous PSA-NCAM. Polysialylation by PSTNm occurred in vivo in less than 2.5 h, persisted in tissues, and then decreased within a few weeks. Together these characteristics suggest that a PSTNm-based approach may provide a valuable alternative to PST gene therapy. DA - 2012/07/31 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b773fd80-ec49-43c5-9171-de75bcb5f0fa ER - TY - JOUR TI - Differential glycosylation of polar and lateral flagellins in Aeromonas hydrophila AH-3 DO - 10.1074/jbc.M112.376525 AU - Wilhelms, Markus AU - Fulton, Kelly M. AU - Twine, Susan M. AU - Tomas, Juan M. AU - Merino, Susana T2 - Journal of Biological Chemistry SN - 0021-9258 SN - 1083-351X VL - 287 IS - 33 SP - 27851 EP - 27862 KW - Bacteria; Genetics; Glycoprotein; Molecular Biology; Mutagenesis; Flagellin; Mass Spectrometry; Pseudaminic Acid AB - Polar and lateral flagellin proteins from Aeromonas hydrophila strain AH-3 (serotype O34) were found to be glycosylated with different carbohydrate moieties. The lateral flagellin was modified at three sites in O-linkage, with a single monosaccharide of 376 Da, which we show to be a pseudaminic acid derivative. The polar flagellin was modified with a heterogeneous glycan, comprised of a heptasaccharide, linked through the same 376-Da sugar to the protein backbone, also in O-linkage. In-frame deletion mutants of pseudaminic acid biosynthetic genes pseB and pseF homologues resulted in abolition of polar and lateral flagellar formation by posttranscriptional regulation of the flagellins, which was restored by complementation with wild type pseB or F homologues or Campylobacter pseB and F. DA - 2012/06/25 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 231964a8-d413-4bfe-85a1-ecb09a19ef3f ER - TY - JOUR TI - Secondary cell wall polymers of Enterococcus faecalis are critical for resistance to complement activation via mannose-binding lectin DO - 10.1074/jbc.M112.358283 AU - Geiss-liebisch, Stefan AU - Rooijakkers, Suzan H. M. AU - Beczala, Agnieszka AU - Sanchez-Carballo, Patricia AU - Kruszynska, Karolina AU - Repp, Christian AU - Sakinc, Tuerkan AU - Vinogradov, Evgeny AU - Holst, Otto AU - Huebner, Johannes AU - Theilacker, Christian T2 - Journal of Biological Chemistry SN - 0021-9258 SN - 1083-351X VL - 287 IS - 45 SP - 37769 EP - 37777 KW - Bacterial Pathogenesis; Cell Wall; Immunology; Innate Immunity; Polysaccharide; Enterococcus faecalis; Complement System; Mannose-binding Lectin; Teichoic Acid AB - The complement system is part of our first line of defense against invading pathogens. The strategies used by Enterococcus faecalis to evade recognition by human complement are incompletely understood. In this study, we identified an insertional mutant of the wall teichoic acid (WTA) synthesis gene tagB in E. faecalis V583 that exhibited an increased susceptibility to complement-mediated killing by neutrophils. Further analysis revealed that increased killing of the mutant was due to a higher rate of phagocytosis by neutrophils, which correlated with higher C3b deposition on the bacterial surface. Our studies indicated that complement activation via the lectin pathway was much stronger on the tagB mutant compared with wild type. In concordance, we found an increased binding of the key lectin pathway components mannose-binding lectin and mannose-binding lectin-associated serine protease-2 (MASP-2) on the mutant. To understand the mechanism of lectin pathway inhibition by E. faecalis, we purified and characterized cell wall carbohydrates of E. faecalis wild type and V583ΔtagB. NMR analysis revealed that the mutant strain lacked two WTAs with a repeating unit of →6)[α-L-Rhap-(1→3)]β-D-GalpNAc-(1→5)-Rbo-1-P and →6) β-D-Glcp-(1→3) [α-D-Glcp-(1→4)]-β-D-GalpNAc-(1→5)-Rbo-1-P→, respectively (Rbo, ribitol). In addition, compositional changes in the enterococcal rhamnopolysaccharide were noticed. Our study indicates that in E. faecalis, modification of peptidoglycan by secondary cell wall polymers is critical to evade recognition by the complement system. DA - 2012/08/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 77515935-04bd-4412-9a81-9e728fd6465c ER - TY - JOUR TI - ¹H NMR metabolomics analysis of glioblastoma subtypes: correlation between metabolomics and gene expression characteristics DO - 10.1074/jbc.M111.337196 AU - Cuperlovic-Culf, Miroslava AU - Ferguson, Dean AU - Culf, Adrian AU - Morin Jr, Pier AU - Touaibia, Mohamed T2 - Journal of Biological Chemistry SN - 0021-9258 SN - 1083-351X VL - 287 IS - 24 SP - 20164 EP - 20175 KW - bioinformatics; glioblastoma; metabolomics; transcriptomics; tumor metabolism AB - Glioblastoma multiforme (GBM) is the most common form of malignant glioma, characterized by unpredictable clinical behaviors that suggest distinct molecular subtypes. With the tumor metabolic phenotype being one of the hallmarks of cancer, we have set upon to investigate whether GBMs show differences in their metabolic profiles. ¹H NMR analysis was performed on metabolite extracts from a selection of nine glioblastoma cell lines. Analysis was performed directly on spectral data and on relative concentrations of metabolites obtained from spectra using a multivariate regression method developed in this work. Both qualitative and quantitative sample clustering have shown that cell lines can be divided into four groups for which the most significantly different metabolites have been determined. Analysis shows that some of the major cancer metabolic markers (such as choline, lactate, and glutamine) have significantly dissimilar concentrations in different GBM groups. The obtained lists of metabolic markers for subgroups were correlated with gene expression data for the same cell lines. Metabolic analysis generally agrees with gene expression measurements, and in several cases, we have shown in detail how the metabolic results can be correlated with the analysis of gene expression. Combined gene expression and metabolomics analysis have shown differential expression of transporters of metabolic markers in these cells as well as some of the major metabolic pathways leading to accumulation of metabolites. Obtained lists of marker metabolites can be leveraged for subtype determination in glioblastomas. DA - 2012/04/23 PY - 2012 PB - American Society for Biochemistry and Molecular Biology LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 84a6222c-b0f2-4dfa-8933-b33473b45622 ER - TY - JOUR TI - Energy landscape analysis of native folding of the prion protein yields the diffusion constant, transition path time, and rates DO - 10.1073/pnas.1206190109 AU - Yu, Hao AU - Gupta, Amar Nath AU - Liu, Xia AU - Neupane, Krishna AU - Brigley, Angela M. AU - Sosova, Iveta AU - Woodside, Michael T. T2 - Proceedings of the National Academy of Sciences of the United States of America SN - 0027-8424 SN - 1091-6490 VL - 109 IS - 36 SP - 14452 EP - 14457 KW - kinetics; optical trapping; single molecule AB - Protein folding is described conceptually in terms of diffusion over a configurational free-energy landscape, typically reduced to a one-dimensional profile along a reaction coordinate. In principle, kinetic properties can be predicted directly from the landscape profile using Kramers theory for diffusive barrier crossing, including the folding rates and the transition time for crossing the barrier. Landscape theory has been widely applied to interpret the time scales for protein conformational dynamics, but protein folding rates and transition times have not been calculated directly from experimentally measured free-energy profiles. We characterized the energy landscape for native folding of the prion protein using force spectroscopy, measuring the change in extension of a single protein molecule at high resolution as it unfolded/refolded under tension. Key parameters describing the landscape profile were first recovered from the distributions of unfolding and refolding forces, allowing the diffusion constant for barrier crossing and the transition path time across the barrier to be calculated. The full landscape profile was then reconstructed from force-extension curves, revealing a double-well potential with an extended, partially unfolded transition state. The barrier height and position were consistent with the previous results. Finally, Kramers theory was used to predict the folding rates from the landscape profile, recovering the values observed experimentally both under tension and at zero force in ensemble experiments. These results demonstrate how advances in single-molecule theory and experiment are harnessing the power of landscape formalisms to describe quantitatively the mechanics of folding. DA - 2012/08/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 48ab5d3f-04a8-4d6e-a68a-32e8eb05ae74 ER - TY - JOUR TI - Ammonia clathrate hydrates as new solid phases for Titan, Enceladus, and other planetary systems DO - 10.1073/pnas.1205820109 AU - Shin, Kyuchul AU - Kumar, Rajnish AU - Udachin, Konstantin A. AU - Alavi, Saman AU - Ripmeester, John A. T2 - Proceedings of the National Academy of Sciences of the United States of America SN - 0027-8424 SN - 1091-6490 VL - 109 IS - 37 SP - 14785 EP - 14790 KW - ice; single crystal X-ray diffraction; hydrogen bonding; hydrate inhibitors; ethane AB - There is interest in the role of ammonia on Saturn’s moons Titan and Enceladus as the presence of water, methane, and ammonia under temperature and pressure conditions of the surface and interior make these moons rich environments for the study of phases formed by these materials. Ammonia is known to form solid hemi-, mono-, and dihydrate crystal phases under conditions consistent with the surface of Titan and Enceladus, but has also been assigned a role as water-ice antifreeze and methane hydrate inhibitor which is thought to contribute to the outgassing of methane clathrate hydrates into these moons’ atmospheres. Here we show, through direct synthesis from solution and vapor deposition experiments under conditions consistent with extraterrestrial planetary atmospheres, that ammonia forms clathrate hydrates and participates synergistically in clathrate hydrate formation in the presence of methane gas at low temperatures. The binary structure II tetrahydrofuran + ammonia, structure I ammonia, and binary structure I ammonia + methane clathrate hydrate phases synthesized have been characterized by X-ray diffraction, molecular dynamics simulation, and Raman spectroscopy methods. DA - 2012/09/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fb8d6ead-9110-4ad2-847e-1292ac2db1d3 ER - TY - JOUR TI - Programmed -1 frameshifting efficiency correlates with RNA pseudoknot conformational plasticity, not resistance to mechanical unfolding DO - 10.1073/pnas.1204114109 AU - Ritchie, Dustin B. AU - Foster, Daniel A. N. AU - Woodside, Michael T. T2 - Proceedings of the National Academy of Sciences of the United States of America SN - 0027-8424 SN - 1091-6490 VL - 109 IS - 40 SP - 16167 EP - 16172 KW - force spectroscopy; gene regulation; RNA folding; translation AB - Programmed −1 frameshifting, whereby the reading frame of a ribosome on messenger RNA is shifted in order to generate an alternate gene product, is often triggered by a pseudoknot structure in the mRNA in combination with an upstream slippery sequence. The efficiency of frameshifting varies widely for different sites, but the factors that determine frameshifting efficiency are not yet fully understood. Previous work has suggested that frameshifting efficiency is related to the resistance of the pseudoknot against mechanical unfolding. We tested this hypothesis by studying the mechanical properties of a panel of pseudoknots with frameshifting efficiencies ranging from 2% to 30%: four pseudoknots from retroviruses, two from luteoviruses, one from a coronavirus, and a nonframeshifting bacteriophage pseudoknot. Using optical tweezers to apply tension across the RNA, we measured the distribution of forces required to unfold each pseudoknot. We found that neither the average unfolding force, nor the unfolding kinetics, nor the parameters describing the energy landscape for mechanical unfolding of the pseudoknot (energy barrier height and distance to the transition state) could be correlated to frameshifting efficiency. These results indicate that the resistance of pseudoknots to mechanical unfolding is not a primary determinant of frameshifting efficiency. However, increased frameshifting efficiency was correlated with an increased tendency to form alternate, incompletely folded structures, suggesting a more complex picture of the role of the pseudoknot involving the conformational dynamics. DA - 2012/10/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 72f57cfa-ac7d-49a2-b416-6b292b36ac51 ER - TY - JOUR TI - Charge transport in molecular electronic junctions: compression of the molecular tunnel barrier in the strong coupling regime DO - 10.1073/pnas.1201557109 AU - Sayed, Sayed Y. AU - Fereiro, Jerry A. AU - Yan, Haijun AU - Mccreery, Richard L. AU - Bergren, Adam Johan T2 - Proceedings of the National Academy of Sciences of the United States of America SN - 0027-8424 SN - 1091-6490 VL - 109 IS - 29 SP - 11498 EP - 11503 KW - energy alignment; molecular electronics; electronic coupling; charge transport; Fermi-level pinning AB - Molecular junctions are essentially modified electrodes familiar to electrochemists where the electrolyte is replaced by a conducting “contact.” It is generally hypothesized that changing molecular structure will alter system energy levels leading to a change in the transport barrier. Here, we show the conductance of seven different aromatic molecules covalently bonded to carbon implies a modest range (< 0.5 eV) in the observed transport barrier despite widely different free molecule HOMO energies (> 2 eV range). These results are explained by considering the effect of bonding the molecule to the substrate. Upon bonding, electronic inductive effects modulate the energy levels of the system resulting in compression of the tunneling barrier. Modification of the molecule with donating or withdrawing groups modulate the molecular orbital energies and the contact energy level resulting in a leveling effect that compresses the tunneling barrier into a range much smaller than expected. Whereas the value of the tunneling barrier can be varied by using a different class of molecules (alkanes), using only aromatic structures results in a similar equilibrium value for the tunnel barrier for different structures resulting from partial charge transfer between the molecular layer and the substrate. Thus, the system does not obey the Schottky-Mott limit, and the interaction between the molecular layer and the substrate acts to influence the energy level alignment. These results indicate that the entire system must be considered to determine the impact of a variety of electronic factors that act to determine the tunnel barrier. DA - 2012/07/17 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2c24db58-f704-430e-95fe-7924c0171d0b ER - TY - JOUR TI - Direct observation of multiple misfolding pathways in a single prion protein molecule DO - 10.1073/pnas.1107736109 AU - Yu, Hao AU - Liu, Xia AU - Neupane, Krishna AU - Gupta, Amar Nath AU - Brigley, Angela M. AU - Solanki, Allison AU - Sosova, Iveta AU - Woodside, Michael T. T2 - Proceedings of the National Academy of Sciences of the United States of America SN - 0027-8424 SN - 1091-6490 VL - 109 IS - 14 SP - 5283 EP - 5288 KW - protein folding; optical tweezers AB - Protein misfolding is a ubiquitous phenomenon associated with a wide range of diseases. Single-molecule approaches offer a powerful tool for deciphering the mechanisms of misfolding by measuring the conformational fluctuations of a protein with high sensitivity. We applied single-molecule force spectroscopy to observe directly the misfolding of the prion protein PrP, a protein notable for having an infectious misfolded state that is able to propagate by recruiting natively folded PrP. By measuring folding trajectories of single PrP molecules held under tension in a high-resolution optical trap, we found that the native folding pathway involves only two states, without evidence for partially folded intermediates that have been proposed to mediate misfolding. Instead, frequent but fleeting transitions were observed into off-pathway intermediates. Three different misfolding pathways were detected, all starting from the unfolded state. Remarkably, the misfolding rate was even higher than the rate for native folding. A mutant PrP with higher aggregation propensity showed increased occupancy of some of the misfolded states, suggesting these states may act as intermediates during aggregation. These measurements of individual misfolding trajectories demonstrate the power of single-molecule approaches for characterizing misfolding directly by mapping out nonnative folding pathways. DA - 2012/04/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c3eda0d8-9c42-448b-922d-6f712a6e94fd ER - TY - JOUR TI - Vertebrate-like regeneration in the invertebrate chordate amphioxus DO - 10.1073/pnas.1100045109 AU - Somorjai, Ildikó M. L. AU - Somorjai, Rajmund L. AU - Garcia-fernandez, Jordi AU - Escriva, Hector T2 - Proceedings of the National Academy of Sciences of the United States of America SN - 0027-8424 SN - 1091-6490 VL - 109 IS - 2 SP - 517 EP - 522 KW - invertebrate chordate-vertebrate transition; stem cells; cephalochordate AB - An important question in biology is why some animals are able to regenerate, whereas others are not. The basal chordate amphioxus is uniquely positioned to address the evolution of regeneration. We report here the high regeneration potential of the European amphioxus Branchiostoma lanceolatum. Adults regenerate both anterior and posterior structures, including neural tube, notochord, fin, and muscle. Development of a classifier based on tail regeneration profiles predicts the assignment of young and old adults to their own class with >94% accuracy. The process involves loss of differentiated characteristics, formation of an msx-expressing blastema, and neurogenesis. Moreover, regeneration is linked to the activation of satellite-like Pax3/7 progenitor cells, the extent of which declines with size and age. Our results provide a framework for understanding the evolution and diversity of regeneration mechanisms in vertebrates. DA - 2012/01/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0d88d5e5-ac42-461a-82f2-a038a18b8537 ER - TY - JOUR TI - A network extraction tool for mineral exploration: a case study from the Wopmay Orogen, Northwest Territories, Canada DO - 10.1071/EG11045 AU - Lee, Madeline AU - Morris, William AU - Harris, Jeff AU - Leblanc, George T2 - Exploration Geophysics SN - 0812-3985 VL - 43 IS - 2 SP - 116 EP - 124 KW - geographic information system, lineament analysis, magnetics, mineral exploration, potential field. AB - Many mineral exploration initiatives target regional- and local-scale lineaments (e.g. fault systems and dyke swarms) as they may act as conduits for mineralized fluids. In this work, we apply an automatic lineament ‘network extraction’ method that draws on similar processes as the Blakely-Simpson peak detection algorithm and a stream network extraction algorithm commonly used in the mapping of drainage patterns from a topographic surface (e.g. DEM, DTM) within a Geographic Information System (GIS) environment. We apply the network extraction algorithm to a magnetic surface (grid) rather than a topographic surface. The method uses a simple quadratic surface across a 3 × 3 window to determine the degree of surface slope and if the centre cell of the window represents a localised low point in the surface. Thus this routine is particularly effective at identifying magnetic lows that may represent faults, which have undergone magnetite depletion (e.g. hematization). These lineament solutions provide insight into mineral exploration vectors through the computation of rose diagrams, fracture density plots and intersection locations. These diagrams, plots, and locations are used in conjunction with other geophysical layers (e.g. radiometrics) to help identify potential mineral exploration targets. We successfully applied this algorithm to an aeromagnetic dataset from the Wopmay Orogen in Northwestern Canada. This area is characterised by extensive regional and localised fault systems and dyke swarms, along with promising polymetallic hydrothermal mineral occurrences. Key areas for follow up exploration are identified through a combined study of geophysical grids and lineament analysis. DA - 2012/03/23 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bec7d2f1-4fd1-4799-9e46-69c73c72051e ER - TY - JOUR TI - A simple adaptable data fusion methodology for geophysical exploration DO - 10.1071/EG11036 AU - Leblanc, George AU - Lee, Madeline AU - Morris, William T2 - Exploration Geophysics SN - 0812-3985 VL - 43 IS - 3 SP - 190 EP - 197 KW - electromagnetics, magnetics, mineral exploration, radiometrics, VLF AB - We present a simple and adaptive method of data fusion using grey-scale grids for general geophysical exploration. The methodology relies upon: (1) understanding the physical property variations that might be associated with the mineral exploration target, and (2) applying appropriate (forward or inverse) grey-scaling to each input dataset so that before addition of the grids the anomalous patterns all express the phenomena of interest in the same sense (i.e. all positive anomalies). If the resulting fused dataset has a Gaussian population distribution then a linear grey-scale is applied to the data within the 95% (2σ) confidence interval; if it is non-Gaussian then the linear grey scale is applied to the entire dataset. The methodology has been applied to very low frequency (VLF), aeromagnetic and radiometric data measured during the 1980s over the Hemlo disseminated lode-gold deposit. The resulting fused data derived from our methodology produces a coherent region of anomalous geophysical response that is coincident in location and geometry to the surficial extent of the known mineralized zone of the deposit. Integration of multi-sensor response has the added advantage of significantly reducing the number of false-targets. Further, this method also illustrates the continued benefits that can be obtained from re-evaluation of older data. DA - 2012/05/25 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 48cf821d-43e3-4734-b7cb-ce6dcf098a8b ER - TY - JOUR TI - The Renner effect in triatomic molecules DO - 10.1063/1.4771743 AU - Bunker, P. R. AU - Kraemer, W. P. AU - Hirano, Tsuneo AU - Jensen, Per T2 - International Conference of Computational Methods in Sciences and Engineering 2009: (ICCMSE 2009) T2 - AIP Conference Proceedings; no. 1504 T3 - International Conference of Computational Methods in Sciences and Engineering 2009: (ICCMSE 2009), 29 September–4 October 2009, Rhodes, Greece SN - 978-0-7354-1122-7 SP - 467 EP - 479 AB - To calculate the rovibronic energies of a triatomic molecule in an electronic state that is degenerate at linear nuclear configurations, it is necessary to allow for the breakdown of the Born-Oppenheimer approximation. This is because the electronic degeneracy is resolved at bent configurations and there is a nonnegligible coupling between the two states caused by molecular rotation. This is termed the Renner (or Renner-Teller) effect. To calculate the rovibronic term values and wavefunctions in this situation, we have developed a variational computational procedure and we have included the effect of spin-orbit coupling for nonsinglet states. The wavefunctions can be used to predict and interpret the results of Coulomb explosion imaging experiments. We can also calculate spectral line intensities so that absorption and emission spectra can be simulated. We review the work and our application to the CH+2 and FeOH molecules. DA - 2012/12/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 77eb0fdf-d281-4460-ad86-b4bdbb4e3741 ER - TY - JOUR TI - Highlighted symposium in computational spectroscopy high precision calculations of molecular energy levels and spectra DO - 10.1063/1.4771738 AU - Bunker, Philip AU - Schwerdtfeger, Peter T2 - International Conference of Computational Methods in Sciences and Engineering 2009: (ICCMSE 2009) T2 - AIP Conference Proceedings; no. 1504 T3 - International Conference of Computational Methods in Sciences and Engineering 2009: (ICCMSE 2009), 29 September–4 October 2009, Rhodes, Greece SN - 978-0-7354-1122-7 SP - 453 DA - 2012/12/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9da5b7d8-33b8-443d-922e-eb906822c896 ER - TY - JOUR TI - The Renner effect in triatomic molecules DO - 10.1063/1.4771724 AU - Bunker, P. R. AU - Kraemer, W. P. AU - Hirano, Tsuneo AU - Jensen, Per T2 - International Conference of Computational Methods in Sciences and Engineering 2009: (ICCMSE 2009) T2 - AIP Conference Proceedings; no. 1504 T3 - International Conference of Computational Methods in Sciences and Engineering 2009: (ICCMSE 2009), 29 September–4 October 2009, Rhodes, Greece SN - 978-0-7354-1122-7 SP - 302 EP - 314 AB - To calculate the rovibronic energies of a triatomic molecule in an electronic state that is degenerate at linear nuclear configurations, it is necessary to allow for the breakdown of the Born-Oppenheimer approximation. This is because the electronic degeneracy is resolved at bent configurations and there is a nonnegligible coupling between the two states caused by molecular rotation. This is termed the Renner (or Renner-Teller) effect. To calculate the rovibronic term values and wavefunctions in this situation, we have developed a variational computational procedure and we have included the effect of spin-orbit coupling for nonsinglet states. The wavefunctions can be used to predict and interpret the results of Coulomb explosion imaging experiments. We can also calculate spectral line intensities so that absorption and emission spectra can be simulated. We review the work and our application to the CH+2 and FeOH molecules. DA - 2012/12/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3b44b345-6c13-4307-ad8b-f1221f9dcfa8 ER - TY - JOUR TI - The rainbow instanton method: A new approach to tunneling splitting in polyatomics DO - 10.1063/1.4769198 AU - Smedarchina, Zorka AU - Siebrand, Willem AU - Fernández-Ramos, Antonio T2 - The Journal of Chemical Physics SN - 0021-9606 VL - 137 IS - 224105 AB - A new instanton approach is reported to tunneling at zero-temperature in multidimensional (MD) systems in which a “light particle” is transferred between two equivalent “heavy” sites. The method is based on two concepts. The first is that an adequate MD potential energy surface can be generated from input of the stationary configurations only, by choosing as a basis the normal modes of the transition state. It takes the form of a double-minimum potential along the mode with imaginary frequency and coupling terms to the remaining (harmonic) oscillators. Standard integrating out of the oscillators gives rise to an effective 1D instanton problem for the adiabatic potential, but requires evaluation of a nonlocal term in the Euclidean action, governed by exponential (memory) kernels. The second concept is that this nonlocal action can be treated as a “perturbation,” for which a new approximate instanton solution is derived, termed the “rainbow” solution. Key to the approach is avoidance of approximations to the exponential kernels, which is made possible by a remarkable conversion property of the rainbow solution. This leads to a new approximation scheme for direct evaluation of the Euclidean action, which avoids the time-consuming search of the exact instanton trajectory. This “rainbow approximation” can handle coupling to modes that cover a wide range of frequencies and bridge the gap between the adiabatic and sudden approximations. It suffers far fewer restrictions than these conventional approximations and is proving particularly effective for systems with strong coupling, such as proton transfer in hydrogen bonds. Comparison with the known exact instanton action in two-dimensional models and application to zero-level tunneling splittings in two isotopomers of malonaldehyde are presented to show the accuracy and efficiency of the approach. DA - 2012/12/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e8ea0ad9-361a-44e3-bbfe-d96273239132 ER - TY - JOUR TI - Time-resolved photoelectron imaging of excited state relaxation dynamics in phenol, catechol, resorcinol, and hydroquinone DO - 10.1063/1.4765104 AU - Livingstone, Ruth A. AU - Thompson, James O. F. AU - Iljina, Marija AU - Donaldson, Ross J. AU - Sussman, Benjamin J. AU - Paterson, Martin J. AU - Townsend, Dave T2 - The Journal of Chemical Physics SN - 0021-9606 VL - 137 IS - 184304 AB - Time-resolved photoelectron imaging was used to investigate the dynamical evolution of the initially prepared S1 (ππ*) excited state of phenol (hydroxybenzene), catechol (1,2-dihydroxybenzene), resorcinol (1,3-dihydroxybenzene), and hydroquinone (1,4-dihydroxybenzene) following excitation at 267 nm. Our analysis was supported by ab initio calculations at the coupled-cluster and CASSCF levels of theory. In all cases, we observe rapid (<1 ps) intramolecular vibrational redistribution on the S1potential surface. In catechol, the overall S1 state lifetime was observed to be 12.1 ps, which is 1–2 orders of magnitude shorter than in the other three molecules studied. This may be attributed to differences in the H atom tunnelling rate under the barrier formed by a conical intersection between the S1 state and the close lying S2 (πσ*) state, which is dissociative along the O–H stretching coordinate. Further evidence of this S1/S2 interaction is also seen in the time-dependent anisotropy of the photoelectron angular distributions we have observed. Our data analysis was assisted by a matrix inversion method for processing photoelectron images that is significantly faster than most other previously reported approaches and is extremely quick and easy to implement. DA - 2012/11/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a44ba4b6-83ac-4ab4-a429-3fd1bf687d2a ER - TY - JOUR TI - Sequence-dependent effects of cryoprotectants on the active sites of the human ABO(H) blood group A and B glycosyltransferases DO - 10.1107/S0907444912001801 AU - Johal, Asha R. AU - Schuman, Brock AU - Alfaro, Javier A. AU - Borisova, Svetlana AU - Seto, Nina O. L. AU - Evans, Stephen V. T2 - Acta Crystallographica Section D: Biological Crystallography SN - 0907-4449 SN - 1399-0047 VL - 68 IS - 3 SP - 268 EP - 276 KW - cryoprotectants; glycosyltransferases; GTA; GTB AB - The human ABO(H) A and B blood group glycosyltransferases GTA and GTB differ by only four amino acids, yet this small dissimilarity is responsible for significant differences in biosynthesis, kinetics and structure. Like other glycosyltransferases, these two enzymes have been shown to recognize substrates through dramatic conformational changes in mobile polypeptide loops surrounding the active site. Structures of GTA, GTB and several chimeras determined by single-crystal X-ray diffraction demonstrate a range of susceptibility to the choice of cryoprotectant, in which the mobile polypeptide loops can be induced by glycerol to form the ordered closed conformation associated with substrate recognition and by MPD [hexylene glycol, (±)-2-methyl-2,4-pentanediol] to hinder binding of substrate in the active site owing to chelation of the Mn²⁺ cofactor and thereby adopt the disordered open state. Glycerol is often avoided as a cryoprotectant when determining the structures of carbohydrate-active enzymes as it may act as a competitive inhibitor for monosaccharide ligands. Here, it is shown that the use of glycerol as a cryoprotectant can additionally induce significant changes in secondary structure, a phenomenon that could apply to any class of protein. DA - 2012/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7c7e95db-0739-4171-a1bb-a838cb549734 ER - TY - JOUR TI - Time-of-flight Bragg scattering from aligned stacks of lipid bilayers using the Liquids Reflectometer at the Spallation Neutron Source DO - 10.1107/S0021889812039945 AU - Pan, Jianjun AU - Heberle, Frederick A. AU - Carmichael, Justin R. AU - Ankner, John F. AU - Katsaras, John T2 - Journal of Applied Crystallography SN - 0021-8898 SN - 1600-5767 VL - 45 IS - 6 SP - 1219 EP - 1227 KW - time-of-flight neutron diffraction; Spallation Neutron Source; Liquids Reflectometer; lipid bilayers AB - Time-of-flight (TOF) neutron diffraction experiments on aligned stacks of lipid bilayers using the horizontal Liquids Reflectometer at the Spallation Neutron Source are reported. Specific details are given regarding the instrumental setup, data collection and reduction, phase determination of the structure factors, and reconstruction of the one-dimensional neutron scattering length density (NSLD) profile. The validity of using TOF measurements to determine the one-dimensional NSLD profile is demonstrated by reproducing the results of two well known lipid bilayer structures. The method is then applied to show how an antimicrobial peptide affects membranes with and without cholesterol. DA - 2012/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b1027399-6580-4cbb-972e-a21548a46120 ER - TY - JOUR TI - Broadband Purcell enhanced emission dynamics of quantum dots in linear photonic crystal waveguides DO - 10.1063/1.4764923 AU - Laucht, A. AU - Günthner, T. AU - Pütz, S. AU - Saive, R. AU - Frédérick, S. AU - Hauke, N. AU - Bichler, M. AU - Amann, M.-C. AU - Holleitner, A. W. AU - Kaniber, M. AU - Finley, J. J. T2 - Journal of Applied Physics SN - 0021-8979 VL - 112 IS - 9 SP - 093520 AB - The authors investigate the spontaneous emission dynamics of self-assembled InGaAs quantum dots embedded in GaAs photonic crystal waveguides. For an ensemble of dots coupled to guided modes in the waveguide, we report spatially, spectrally, and time-resolved photoluminescence measurements, detecting normal to the plane of the photonic crystal. For quantum dots emitting in resonance with the waveguide mode, an ∼21× enhancement of photoluminescence intensity is observed as compared to dots in the unprocessed region of the wafer. This enhancement can be traced back to the Purcell enhanced emission of quantum dots into leaky and guided modes of the waveguide with moderate Purcell factors up to ∼4×. Emission into guided modes is shown to be efficiently scattered out of the waveguide within a few microns, contributing to the out-of-plane emission and allowing the use of photonic crystal waveguides as broadband, efficiency-enhancing structures for surface-emitting diodes or single photon sources. DA - 2012/11/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4269eed8-f511-41a9-b187-c8a1b3c8031f ER - TY - JOUR TI - A little ribbing: flux starvation engineering for rippled indium tin oxide nanotree branches DO - 10.1063/1.4764508 AU - Tucker, Ryan T. AU - Beaudry, Allan L. AU - LaForge, Joshua M. AU - Taschuk, Michael T. AU - Brett, Michael J. T2 - Applied Physics Letters SN - 0003-6951 VL - 101 IS - 193101 AB - Combining vapour-liquid-solid growth with glancing angle deposition (VLS-GLAD) facilitates fabrication of branched nanowires not possible with either technique alone. Indiumtin oxide (ITO) nanostructuresgrown by VLS-GLAD produce extremely porous nanotree structures, where periodic branch diameter oscillations are sometimes observed. We explain this rippled branch growth with a simple model linking the physics governing branch growth to the process variables controlled in VLS-GLAD. The model is verified by inducing specific, aperiodic ripples onto growing ITO branches through macroscopic vapour flux control and manipulation of local shadowing. DA - 2012/11/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4fc33d33-7aed-4495-ba5d-4d003d15572a ER - TY - JOUR TI - A semiconductor under insulator technology in indium phosphide DO - 10.1063/1.4760231 AU - Mnaymneh, K. AU - Dalacu, D. AU - Frédérick, S. AU - Lapointe, J. AU - Poole, P. J. AU - Williams, R. L. T2 - Applied Physics Letters SN - 0003-6951 VL - 101 IS - 151120 AB - This letter introduces a semiconductor-under-insulator (SUI) technology in InP for designing strip waveguides that interfaceInPphotonic crystal membrane structures. Strip waveguides in InP-SUI are supported under an atomic layer deposited insulator layer in contrast to strip waveguides in silicon supported oninsulator. We show a substantial improvement in optical transmission when using InP-SUI strip waveguides interfaced with localized photonic crystal membrane structures when compared with extended photonic crystal waveguide membranes. Furthermore, SUI makes available various fiber-coupling techniques used in SOI, such as sub-micron coupling, for planar membrane III-V systems. DA - 2012/10/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c17d99ba-6d54-4401-80e1-a95ea9a2849a ER - TY - JOUR TI - Omnidirectional reflection from nanocolumnar TiO2 films DO - 10.1063/1.4759138 AU - Leontyev, Viktor AU - Hawkeye, Matthew AU - Kovalenko, Andriy AU - Brett, Michael J. T2 - Journal of Applied Physics SN - 0021-8979 VL - 112 IS - 8 SP - 084317 AB - Anisotropic properties of columnar nanoporous thin films were utilized to design and fabricate interference mirrors with lossless omnidirectional reflection in the visible spectral range. Index graded columnar films with distributed Bragg reflector (DBR), sinusoidal, and Gaussian refractive index profiles were studied using finite-difference frequency-domain and finite-difference time-domain methods, with an emphasis on maximizing the omnidirectional reflection bandwidth. Titanium dioxide columnar films with sixteen period sinusoidal refractive index profile were fabricated using the glancing angle deposition technique and characterized by angle resolved transmittance measurements. Simulations and experimental measurements have shown the presence of the omnidirectional reflection band up to 5% wide for a film with a maximum refractive index nmax=2.3 and refractive index contrast Δn=0.8. Simulations further showed that with the optimal choice of the refractive index variation range, the omnidirectional reflection band can reach 10.5% width in TiO2films with a sinusoidal index profile, 14.5% with a DBR index profile, and 12% with a Gaussian profile. Due to the optical anisotropy of the columnar films, the reflection bandwidth exceeded the corresponding value, observed in isotropic analogs, by a factor of three to four depending on the choice of the refractive index profile. DA - 2012/10/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 75e37fab-fe33-44f6-a331-0fac7da875da ER - TY - JOUR TI - Assembled Fe3O4 nanoparticles on graphene for enhanced electromagnetic wave losses DO - 10.1063/1.4758931 AU - Guan, P. F. AU - Zhang, X. F. AU - Guo, J. J. T2 - Applied Physics Letters SN - 0003-6951 VL - 101 IS - 153108 AB - We present an one-step procedure for the synthesis of hybrid Fe3O4 nanoparticles/graphene composite with self-assemble superlattices of Fe3O4nanoparticles. We find that the Fe3O4/graphene nanocomposite exhibits both enhanced dielectric losses and magnetic losses at 2–18 GHz, resulting from the interfacial polarizations between the Fe3O4nanoparticles and the graphene, as well as the coupling between the neighbouring Fe3O4nanoparticles. Theoretical simulations uncover the origins of the electromagnetic losses of hybrid Fe3O4/graphene nanocomposite and provide additional insight into the microscopic dielectric polarization mechanism. DA - 2012/10/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ac00ff83-c1cc-4b20-989f-e0c7aa38baa0 ER - TY - JOUR TI - Enhanced charge detection of spin qubit readout via an intermediate state DO - 10.1063/1.4749281 AU - Studenikin, S. A. AU - Thorgrimson, J. AU - Aers, G. C. AU - Kam, A. AU - Zawadzki, P. AU - Wasilewski, Z. R. AU - Bogan, A. AU - Sachrajda, A. S. T2 - Applied Physics Letters SN - 0003-6951 VL - 101 IS - 23 SP - 233101 AB - We employ an intermediate excited charge state of a lateral quantum dot device to increase the charge detection contrast during the qubit state readout procedure, allowing us to increase the visibility of coherent qubit oscillations. This approach amplifies the coherent oscillation magnitude but has no effect on the detector noise resulting in an increase in the signal to noise ratio. In this letter, we apply this scheme to demonstrate a significant enhancement of the fringe contrast of coherent Landau-Zener-Stückelberg oscillations between singlet S and triplet two-spin states. DA - 2012/12/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 128b6697-2061-4b4a-b905-875280a0db1d ER - TY - JOUR TI - Effect of small cage guests on hydrogen bonding of tetrahydrofuran in binary structure II clathrate hydrates DO - 10.1063/1.4739928 AU - Alavi, Saman AU - Ripmeester, John A. T2 - The Journal of Chemical Physics SN - 0021-9606 VL - 137 IS - 054712 AB - Molecular dynamics simulations of the pure structure II tetrahydrofuran clathrate hydrate and binary structure II tetrahydrofuran clathrate hydrate with CO2, CH4, H2S, and Xe small cage guests are performed to study the effect of the shape, size, and intermolecular forces of the small cages guests on the structure and dynamics of the hydrate. The simulations show that the number and nature of the guest in the small cage affects the probability of hydrogen bonding of the tetrahydrofuran guest with the large cage water molecules. The effect on hydrogen bonding of tetrahydrofuran occurs despite the fact that the guests in the small cage do not themselves form hydrogen bonds with water. These results indicate that nearest neighbour guest-guest interactions (mediated through the water lattice framework) can affect the clathrate structure and stability. The implications of these subtle small guest effects on clathrate hydrate stability are discussed. DA - 2012/08/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bdca4f5b-dbca-4d11-a8e5-17dc8330622c ER - TY - JOUR TI - New infrared bands of nonpolar OCS dimer and experimental frequencies for two intermolecular modes DO - 10.1063/1.4739465 AU - Afshari, M. AU - Dehghany, M. AU - McKellar, A. R. W AU - Moazzen-Ahmadi, N. T2 - The Journal of Chemical Physics SN - 0021-9606 VL - 137 IS - 5 SP - 054304 AB - Spectra of the nonpolar carbonyl sulfide dimer in the region of the OCS ν1 fundamental band were observed in a slit-jet supersonic expansion. The jet was probed using radiation from a tunable diode laser employed in a rapid-scan signal averaging mode. Six new bands were observed and analyzed, all of which originate from the dimer ground vibrational state. Three were vibrational fundamentals involving the (18OCS)2 and 16OCS-18OCS isotopologues. They enabled an estimate to be made of the frequency of the infrared-forbidden mode corresponding to in-phase vibration of the OCS monomers in the dimer, a value needed to obtain an intermolecular vibrational frequency from one of the observed combination bands. A relatively weak b-type dimer band centered at 2103.105 cm−¹ was assigned to the OCS 4ν2 (l = 0) bending overtone. Combination bands were observed involving the geared bend and van der Waals stretch intermolecular modes. The resulting experimental frequencies of 37.5(20) cm−¹ for the bend and 42.9727(1) cm−¹ for the stretch are in good agreement with a recent high level theoretical calculation. DA - 2012/08/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 39ae02ae-306b-4927-98da-5df8ef40eeed ER - TY - JOUR TI - Self-organized InAs/InGaAsP quantum dot tube lasers DO - 10.1063/1.4737425 AU - Bianucci, Pablo AU - Mukherjee, Shouvik AU - Dastjerdi, M. Hadi Tavakoli AU - Poole, Philip J. AU - Mi, Zetian T2 - Applied Physics Letters SN - 0003-6951 VL - 101 IS - 3 SP - 031104 AB - We report the achievement of a semiconductor tube laser that can operate in the optical communication wavelength range for applications in the emerging Si-photonics. Such nanoscale devices are fabricated from self-organized InAs/InGaAsP quantum dotnanomembranes through a strain-driven self-rolling mechanism using standard photolithography process. Under continuous wave optical pumping, the devices exhibit an ultralow lasing threshold of ∼1.26 μW at 82 K, with multiple emission wavelengths in the S band of optical communications. The spontaneous emission coupling factor and Purcell factor are estimated to be ∼0.30 and ∼4.8, respectively. DA - 2012/07/17 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3b30e62d-cc26-4cfc-8b98-6aba71f27053 ER - TY - JOUR TI - Magnetooptic coupling coefficients for one- and two-magnon Raman scattering in rutile-structure antiferromagnets FeF₂, MnF₂, CoF₂, and NiF₂ DO - 10.1063/1.4733682 AU - Lockwood, D. J. AU - Cottam, M. G. T2 - Low Temperature Physics T2 - Fizika Nizkikh Temperatur SN - 1063-777X SN - 0132-6414 VL - 38 IS - 7 SP - 703 EP - 714 KW - Antiferromagnets KW - Coupling coefficient KW - Ferrimagnets KW - In-phase KW - Inelastic light scattering KW - Magnetic excitations KW - Magnetic insulator KW - Magnons KW - Metamagnets KW - One-magnon Raman scattering KW - Quadratic coefficients KW - Rutile structure KW - Theoretical investigations KW - Two-magnon Raman scattering KW - Wave vector KW - Oxide minerals KW - Raman scattering KW - Antiferromagnetic materials AB - Inelastic light scattering intensities in response to magnetic excitations are governed by magnetooptic coupling coefficients, which have been previously evaluated, for instance, for the ferrimagnetic Y3Fe5O12 (YIG) and the metamagnetic FeCl2 and FeBr2. However, by far the most detailed studies to date were performed on the classic rutile-structure antiferromagnets, and here we summarize the results obtained from the many experimental and theoretical investigations of these compounds for both one-magnon and two-magnon excitations. A comparison of the magnitudes of the various coupling coefficients for MnF2, FeF2, CoF2, and NiF2 reveals a surprising similarity in many coefficients. In one-magnon Raman scattering the in-phase linear magnetooptic coefficient dominates, and the main differences between MnF2, FeF2, and NiF2 lie in the relative significance of the in-phase quadratic magnetooptic coefficient. Thus, the quadratic coefficients now appear to be of particular importance in determining the strength of one-magnon scattering in a variety of magnetic insulators. In two-magnon Raman scattering one magnetooptic coefficient is dominant for all of these antiferromagnets. However, the other six coefficients are in general remarkably similar in magnitude and not negligible in most cases, indicating some similarity in the way light interacts with the pairs of magnons of opposite and equal wave vectors in rutile structure antiferromagnets. DA - 2012/07/27 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 86ddec13-e1a5-4532-b375-a661db4a6cf5 ER - TY - JOUR TI - Nanophotonic detection of side-coupled nanomechanical cantilevers DO - 10.1063/1.4731210 AU - Sauer, V. T. K. AU - Diao, Z. AU - Freeman, M. R. AU - Hiebert, W. K. T2 - Applied Physics Letters SN - 0003-6951 VL - 100 IS - 261102 AB - A silicon nanophotonic Mach-Zehnder interferometer (MZI) is used to detect the mechanical resonance of a cantilever external to a nanophotonicwaveguide. Small cantilever devices, below the cut-off for waveguide supported modes, are fabricated ∼140 nm away from one MZI arm. Cantilever resonant frequencies up to 60 MHz are measured with mechanical quality factors around 20 000 and signal to noise ratios up to 1000. Phase-locked loop frequency stability measurements indicate a mass sensitivity of 2 zg in an example cantilever of 0.5 pg mass. An interferometric transduction mechanism is confirmed, and the system is shown to work effectively in all-optical operation. DA - 2012/06/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 322969ea-9698-40ad-b74b-a8f619fc26a0 ER - TY - JOUR TI - Spectroscopic observation of nitrous oxide pentamers DO - 10.1063/1.4729157 AU - Rezaei, Mojtaba AU - Oliaee, J. Norooz AU - Moazzen-Ahmadi, N. AU - McKellar, A. R. W. T2 - The Journal of Chemical Physics SN - 0021-9606 VL - 136 IS - 224308 AB - Two new infrared bands in the ν1 fundamental region of N2O are observed in a supersonic jet expansion and assigned to nitrous oxide pentamers. Each band is measured using both 14N2 16O and 15N2 16O. Although they are similar in appearance, the bands have slightly different lower state rotational parameters, and are thus assigned to distinct structural isomers of the pentamer. Cluster calculations using two N2O intermolecular potentials give results in good agreement with the observed spectra, and indicate that the two isomers probably have the same basic structure (which is unsymmetrical), but differ in the alignment (N-N-O or O-N-N) of one or two of the constituent monomers. Calculations using a resonant dipole interaction model also support the proposed assignment and structure. These are the first reported high-resolution spectra for N2O pentamers. DA - 2012/06/14 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6c0fb0a3-36aa-48e3-8d79-c2597eb2eb10 ER - TY - JOUR TI - Excitation wavelength dependent photoluminescence in structurally non-uniform Si/SiGe-island heteroepitxial multilayers DO - 10.1063/1.4729077 AU - Modi, N. AU - Lockwood, D. J. AU - Wu, X. AU - Baribeau, J.-M. AU - Tsybeskov, L. T2 - Journal of Applied Physics SN - 0021-8979 VL - 111 IS - 114313 AB - In nanometer-size Si/SiGe-island heteroepitxial multilayers grown on Si(001), low temperature photoluminescence spectra are observed that strongly depend on the excitation wavelength and show a strong correlation with structural properties revealed by transmission electron microscopy. These experimental results can be explained by assuming that the optically created carriers are strongly localized at Si/SiGe island heterointerfaces. We show that electron-hole pairs are generated and recombine within spatial regions mainly defined by the photoexcitation penetration depth, and that the estimated exciton diffusion length is notably short and comparable with the SiGe-island average size. DA - 2012/06/14 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 44fe77a2-3957-4e5a-a078-67449e1d8dd0 ER - TY - JOUR TI - Gas field ion source current stability for trimer and single atom terminated W(111) tips DO - 10.1063/1.4726112 AU - Urban, Radovan AU - Pitters, Jason L. AU - Wolkow, Robert A. T2 - Applied Physics Letters SN - 0003-6951 VL - 100 IS - 263105 AB - Tungsten W(111) oriented trimer-terminated tips as well as single atom tips, fabricated by a gas and field assisted etching and evaporation process, were investigated with a view to scanning ion microscopy and ion beam writing applications. In particular, ion current stability was studied for helium and neon imaging gases. Large ion current fluctuations from individual atomic sites were observed when a trimer-terminated tip was used for the creation of neon ion beam. However, neon ion current was stable when a single atom tip was employed. No such current oscillations were observed for either a trimer or a single atom tip when imaged with helium. DA - 2012/06/26 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 21db37cd-216a-4a78-a6a4-5a4702f45fbf ER - TY - JOUR TI - Pulsed thermography image processing for damage growth monitoring DO - 10.1063/1.4716297 AU - Genest, M. T2 - Review of progress in quantitative nondestructive evaluation : Burlington, Vermont, USA : 17-22 July 2011 T2 - AIP Conference Proceedings; no. 1430 T3 - Review of Progress in Quantitative Nondestructive Evaluation, July 17–22, 2011, Burlington, Vermont, USA SN - 9780735410138 SN - 0735410135 SP - 721 EP - 728 AB - An image processing algorithm based on a combination of the most commonly used signal processing techniques in pulsed thermography is applied to monitor the progression of impact damage sites during the full-scale testing of a composite test article. It is demonstrated that the algorithm can be used to monitor damage during a durability and damage tolerance testing. Over the first phase of the test program, although no damage growth was detected, the processed pulsed thermography images showed that the average standard deviation of the measurements was only ~0.08 inches, the equivalent of 2 infrared camera pixels. DA - 2012/05/17 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4ffc5468-1ae5-4c80-ac43-cddf006f37c5 ER - TY - JOUR TI - Dynamics of localized excitons in Ga0.69In0.31N0.015As0.985/GaAs quantum well: experimental studies and Monte-Carlo simulations DO - 10.1063/1.4714739 AU - Baranowski, M. AU - Kudrawiec, R. AU - Latkowska, M. AU - Syperek, M. AU - Misiewicz, J. AU - Gupta, J. A. T2 - Applied Physics Letters SN - 0003-6951 VL - 100 IS - 202105 AB - Time resolved photoluminescence (PL) spectroscopy has been applied to study dynamics of localized excitons in a single Ga0.7In0.3N0.015As0.985/GaAs quantum well(QW). The decay time constant, τPL, has been determined for different PL peak energies at various temperatures. An increase in temperature produced two effects: (i) a reduction of τPL and (ii) changes in the τPLdispersion. These two experimental observations as well as the shape of PL decay curves were very well reproduced by Monte-Carlo simulations of hopping excitons with parameters derived from PL and photoreflectance measurements for this QW. DA - 2012/05/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 22d818ea-2bb7-42e2-90e2-9e1b1ea6d011 ER - TY - JOUR TI - Photovoltaic infrared detection with p-type graded barrier heterostructures DO - 10.1063/1.4704695 AU - Pitigala, P. K. D. D. P. AU - Matsik, S. G. AU - Perera, A. G. U. AU - Khanna, S. P. AU - Li, L. H. AU - Linfield, E. H. AU - Wasilewski, Z. R. AU - Buchanan, M. AU - Liu, H. C. T2 - Journal of Applied Physics SN - 00218979 VL - 111 IS - 8 SP - 084505 AB - Photovoltaicinfrared detectors have significant advantages over photoconductive detectors due to zero bias operation, requiring low power and having reduced low frequency noise. They also exhibit no thermally assisted tunneling currents, leading to higher operating temperatures. p-type emitter/graded barrier GaAs/AlxGa1−xAs structures were tested as photovoltaicdetectors in the infrared region, operating under uncooled conditions and without an applied bias voltage. A photovoltaic responsivity of 450 mV/W was obtained with a detectivity (D*) of 1.2 × 10^6 Jones at a peak wavelength 1.8 μm at 300 K. Responsivity and D* increased to ∼1.2 V/W and 2.8 × 10^6 Jones, respectively, at 280 K. A non-linear improvement in responsivity was observed with increased emitter thickness. DA - 2012/04/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3190e9e1-000c-4c73-b0dc-cfb2b52b88c6 ER - TY - JOUR TI - Creation and recovery of a W(111) single atom gas field ion source DO - 10.1063/1.3702209 AU - Pitters, Jason L. AU - Urban, Radovan AU - Wolkow, Robert A. T2 - The Journal of Chemical Physics SN - 0021-9606 VL - 136 IS - 15 SP - 154704 AB - Tungsten single atom tips have been prepared from a single crystal W(111) oriented wire using the chemical assisted field evaporation and etching method. Etching to a single atom tip occurs through a symmetric structure and leads to a predictable last atom unlike etching with polycrystalline tips. The single atom tip formation procedure is shown in an atom by atom removal process. Rebuilds of single atom tips occur on the same crystalline axis as the original tip such that ion emission emanates along a fixed direction for all tip rebuilds. This preparation method could be utilized and developed to prepare single atom tips for ion source development. DA - 2012/04/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 618e92ef-752d-4dc1-a535-9ad1607bce0a ER - TY - JOUR TI - First science results with a new, inexpensive liquid crystal polarimeter module for the DAO 1.8m telescope DO - 10.1063/1.3701932 AU - Bohlender, David AU - Monin, Dmitry T2 - Stellar polarimetry : from birth to death T2 - AIP Conference Proceedings; no. 1429 T3 - Stellar Polarimetry: From Birth to Death, June 27–30, 2011, Madison, WI, USA SN - 978-0-7354-1012-1 SP - 240 EP - 243 AB - A new polarimeter module has been built for the Dominion Astrophysical Observatory's (DAO) 1.8m Plaskett telescope for a hardware cost, including spare components, of approximately CDN$5,000. Implemented as a plug-in addition to the telescope's existing Cassegrain spectrograph, the device is being used to obtain medium resolution (R ≈ 10;000) circular spectropolarimetry of stars in an approximately 280Å wide wavelength region centered on the Hβ line. The intermediate resolution of the spectrograph permits stellar longitudinal magnetic field measurements to be made with both single or multiple strong metallic lines as well as the Hβ line. The instrument's dual-beam design together with fast switching of the liquid crystal wave plate (up to 100 Hz) synchronized with charge shuffling on the CCD is used to significantly reduce instrumental effects and achieve high precision polarimetric measurements. In this paper we present the first new science results obtained with the instrument. These include the discovery of a strong magnetic field and co-rotating magnetosphere in the helium-weak star HD176582, the detection of several new magnetic stars, and a study of the observed (and occasionally very large) differences in stellar longitudinal magnetic fields as measured with the Hβ line and metallic lines. DA - 2012/05/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 01576917-e7d5-46d8-9378-eab5bffcd3d0 ER - TY - JOUR TI - Recent developments in submillimeter polarimetry archives, the polarization spectrum and the interpretation of polarization data DO - 10.1063/1.3701894 AU - Matthews, Brenda C. AU - Vaillancourt, John E. T2 - Stellar polarimetry : from birth to death T2 - AIP Conference Proceedings; no. 1429 T3 - Stellar Polarimetry: From Birth to Death, June 27–30, 2011, Madison, WI, USA SN - 978-0-7354-1012-1 SP - 11 EP - 20 AB - Significant progress has been made in our understanding of the power of polarization maps in the submillimeter and millimeter in the past decade. This is made more remarkable by the dearth of new polarimetric facilities over the past 10 years and decommissioning of several long-standing instruments. In particular, we discuss recent work to establish the validity of the previously measured polarization spectrum in the submillimeter, and the enhanced analysis techniques presented in recent years for the interpretation of polarization position angle data without the need for models of the ordered field geometry. DA - 2012/05/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 83ccaab5-68eb-48e9-b4ac-84d7d1b27e20 ER - TY - JOUR TI - Square spiral photonic crystal with visible bandgap DO - 10.1063/1.3695388 AU - Krabbe, Joshua D. AU - Leontyev, Viktor AU - Taschuk, Michael T. AU - Kovalenko, Andriy AU - Brett, Michael J. T2 - Journal of Applied Physics SN - 00218979 VL - 111 IS - 6 SP - 064314 AB - Nanoimprint lithography was combined with glancing angle deposition (GLAD) of titanium dioxide to fabricate a square spiral columnar film with a bandgap in the visible spectral range. Nanoimprint stamps were fabricated with seed spacing ranging from 80 to 400 nm, and four periods of square spiral film were deposited on top of the 320 nm array of seeds. The ratio of lattice spacing, vertical pitch and spiral arm swing was chosen as a : P : A = 1 : 1.35 : 0.7 and the deposition angle was fixed at 86° to maximize the square spiral film’s bandgap.Reflectivity measurements show that the fabricated structure exhibit a pseudo-gap centered at around 600 nm wavelength, in good agreement with finite difference electromagnetic simulations. The absence of a full 3D bandgap is due the deviation of GLAD columns’ cross-section from the optimal one, which has to be highly elongated in the deposition plane. However, simulations show that a geometry close to the fabricated one will produce a full 3D bandgap, if the structure is inverted. The material refractive index in such an inverted photonic crystal can be as low as n = 2.15. DA - 2012/03/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fbdab970-cc63-4810-810d-64c421a4cf76 ER - TY - JOUR TI - A 3-dimensional time-resolved photothermal deflection “Mirage” method DO - 10.1063/1.3691253 AU - Astrath, N. G. C. AU - Malacarne, L. C. AU - Lukasievicz, G. V. B. AU - Bernabe, H. S. AU - Rohling, J. H. AU - Baesso, M. L. AU - Shen, J. AU - Bialkowski, S. E. T2 - Applied Physics Letters SN - 0003-6951 VL - 100 IS - 9 SP - 091908 AB - A three-dimensional time-resolved theory and experiment for photothermal deflection spectroscopy is developed. The heat conduction equations for two semi-infinite media consisting of an opaque sample and a fluid are solved considering temperature and energy flux balance conditions for a Gaussian heat source. The time dependent perpendicular deflection signal is calculated and compared to experimental measurements on glassy carbon and copper samples. Excellent agreement with literature values for thermal diffusivity of the samples is found. The transient behavior is analyzed for different coupling fluids. DA - 2012/03/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 02a9c3fa-e2ab-4f84-a022-013349ef2880 ER - TY - JOUR TI - Could diastereoselectivity in the presence of O-2 chiral nonparticipating groups be an indicator of glycopyranosyl oxacarbenium ions in glycosylation reactions? DO - 10.1021/jo202563f AU - Kumar, Rishi AU - Whitfield, Dennis M. T2 - The Journal of Organic Chemistry SN - 0022-3263 SN - 1520-6904 VL - 77 IS - 8 SP - 3724 EP - 3739 AB - Although long postulated, the existence of glycopyranosyl oxacarbenium ions as intermediates or transition states (TS) in chemical glycosylation reactions has not been convincingly demonstrated experimentally. It is anticipated that elucidation of such reactive species will greatly assist synthetic chemists to control the α/β stereoselectivity by rational means. Previous density functional theory (DFT) calculations from our group found that the torsion potential about C-2–O-2 in protected glycopyranosyl donors changed from a conventional 3-fold rotor to a 2-fold rotor with a strong syn (CH-2–C-2–O-2–CPg) preference once the donor was ionized to its oxacarbenium ion. This suggested to us that if CPg of the protecting group was a chiral carbon, then diastereoselectivity might be observed in glycosylation reactions that proceed through oxacarbenium ions. The hypothesis to test is as follows: if a nonparticipating O-2 racemic chiral protecting group exhibits diastereoselectivity in glycosylation reactions, then the reaction probably proceeds through an oxacarbenium ion intermediate or TS. We present data for O-2 ether-protected d-glucopyranosyl donors where the racemic protecting group 1-methyl 1′-methylcyclopropylmethyl (MCPM) provides the chirality. MCPM proves to be more activating than the O-2-benzyl ether, and in cases where the donor is otherwise deactivated, several examples of moderate diastereoselectivity are found. These results can be interpreted to indicate that a continuum of reactivity exists where some glycosyl donors form oxacarbenium ions in glycosylation reactions but more reactive donors do not. The strongly activating properties of the cyclopropylmethyl ether functionality and the ability to induce diastereoselectivity with chiral derivatives strongly suggest widespread applications. DA - 2012/04/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 44699797-34c5-4ca5-98ba-e9be038ffa6c ER - TY - JOUR TI - Kinetic solvent effects on hydrogen abstraction from phenol by the cumyloxyl radical. Toward an understanding of the role of protic solvents DO - 10.1021/jo201454c AU - Bietti, Massimo AU - Salamone, Michela AU - DiLabio, Gino A. AU - Jockusch, Steffen AU - Turro, Nicholas J. T2 - The Journal of Organic Chemistry SN - 0022-3263 SN - 1520-6904 VL - 77 IS - 3 SP - 1267 EP - 1272 AB - A time-resolved kinetic study of the hydrogen atom abstraction reactions from phenol by the cumyloxyl radical (CumO•) was carried out in different solvents. The hydrogen atom abstraction rate constant (kH) was observed to decrease by almost 3 orders of magnitude on going from isooctane to MeOH. In TFE, MeCN/H2O 2:1, and MeOH, the measured kH values were lower than expected on the basis of the Snelgrove–Ingold (SI) equation that correlates log kH to the solvent hydrogen bond acceptor (HBA) ability parameter β2H. As these solvents also act as hydrogen bond donors (HBDs), we explored the notion that a more thorough description of solvent effects could be provided by including a solvent HBD ability term, α2H, into the SI equation via β2H(1 + α2H). The inclusion of such a term greatly improves the fitting for TFE, MeCN/H2O 2:1, and MeOH but at the expense of that for tertiary alkanols. This finding suggests that, for the reaction of CumO• with phenol, the HBA and HBD abilities of both the solvent and the substrate could be responsible for the observed KSEs. but this requires that primary and tertiary alkanols exhibit different solvation behaviors. Possible explanations for this different behavior are explored. DA - 2012/02/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1c2ac6b8-6f0f-42b8-8a98-f6610607556f ER - TY - JOUR TI - Inhibition of Galactosyltransferases by a Novel Class of Donor Analogues DO - 10.1021/jm201154p AU - Descroix, Karine AU - Pesnot, Thomas AU - Yoshimura, Yayoi AU - Gehrke, Sebastian S. AU - Wakarchuk, Warren AU - Palcic, Monica M. AU - Wagner, Gerd K. T2 - Journal of Medicinal Chemistry SN - 0022-2623 SN - 1520-4804 VL - 55 IS - 5 SP - 2015 EP - 2024 AB - Galactosyltransferases (GalT) are important molecular targets in a range of therapeutic areas, including infection, inflammation, and cancer. GalT inhibitors are therefore sought after as potential lead compounds for drug discovery. We have recently discovered a new class of GalT inhibitors with a novel mode of action. In this publication, we describe a series of analogues which provide insights, for the first time, into SAR for this new mode of GalT inhibition. We also report that a new C-glycoside, designed as a chemically stable analogue of the most potent inhibitor in this series, retains inhibitory activity against a panel of GalTs. Initial results from cellular studies suggest that despite their polarity, these sugar-nucleotides are taken up by HL-60 cells. Results from molecular modeling studies with a representative bacterial GalT provide a rationale for the differences in bioactivity observed in this series. These findings may provide a blueprint for the rational development of new GalT inhibitors with improved potency. DA - 2012/03/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 06099a81-e608-4cc7-a79c-8eb40729c0f5 ER - TY - JOUR TI - Oligosaccharide and peptidoglycan of Ganoderma lucidum activate the immune response in human mononuclear cells DO - 10.1021/jf3000339 AU - Tsai, Chia-Che AU - Yang, Feng-Ling AU - Huang, Zih-You AU - Chen, Chien-Sheng AU - Yang, Yu-Liang AU - Hua, Kuo-Feng AU - Li, Jianjun AU - Chen, Shui-Tein AU - Wu, Shih-Hsiung T2 - Journal of Agricultural and Food Chemistry SN - 0021-8561 SN - 1520-5118 VL - 60 IS - 11 SP - 2830 EP - 2837 KW - Ganoderma lucidum; peptidoglycan; oligosaccharide; glucuronic acid; human mononuclear cells AB - The acid-hydrolyzed fragments of Ganoderma lucidum polysaccharides (GLPS) obtained by Smith degradation were separated by size-exclusion chromatography into two major water-soluble fractions: peptidoglycans (GLPS-SF1) and oligosaccharides (GLPS-SF2). Both fractions induced CD69 in human peripheral blood mononuclear cells (hPB-MNCs), and they displayed distinct immunomodulating properties. GLPS-SF1, with a molecular weight of around 20 kDa, were heterogeneous peptidoglycans composed of glucose/mannose (4:1) that exhibited biological activities with Th1 cytokines IL-12, IL-2, TNF-α, and IFN-γ in hPB-MNCs and stimulated macrophage cytokine expression via Toll-like receptor 4 (TLR4) signaling. For GLPS-SF2, with a molecular weight of around several kilodaltons, its sugar sequence was elucidated by mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy as [−α-1,4-Glc–(β-1,4-GlcA)3−]n. This oligosaccharide displayed specific immune property with low monocyte induction, greatly stimulated cell activation and proliferation of NK and T cells. This oligosaccharide isolated from G. lucidum polysaccharides with internal glucuronic acids/glucose repeat unit in a 3:1 ratio may be responsible for the active stimulation of NK and T cells. DA - 2012/03/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5ef5ac32-e053-42f8-9a6a-a82813d51def ER - TY - JOUR TI - Infrared spectra of CO2-doped hydrogen clusters, (H2)N–CO2 DO - 10.1063/1.3691101 AU - McKellar, A. R. W. T2 - The Journal of Chemical Physics SN - 0021-9606 VL - 136 IS - 094305 AB - Clusters of para-H2 and/or ortho-H2 containing a single carbon dioxide molecule are studied by high resolution infrared spectroscopy in the 2300 cm−¹ region of the CO2 ν3 fundamental band. The (H2) N –CO2 clusters are formed in a pulsed supersonic jet expansion from a cooled nozzle and probed using a rapid scan tunable diode laser. Simple symmetric rotor type spectra are observed with little or no resolved K-structure, and prominent Q-branch features for ortho-H2 but not para-H2. Observed rotational constants and vibrational shifts are reported for ortho-H2 up to N = 7 and para-H2 up to N = 15, with the N > 7 assignments only made possible with the help of theoretical simulations. The para-H2 cluster with N = 12 shows clear evidence for superfluid effects, in good agreement with theory. The presence of larger clusters with N > 15 is evident in the spectra, but specific assignments are not possible. Mixed para- + ortho-H2 cluster transitions are well predicted by linear interpolation between corresponding pure cluster line positions. DA - 2012/03/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : abde461e-7763-419c-a26f-33d3f9c02ff1 ER - TY - JOUR TI - Chemical synthesis and immunological evaluation of the inner core oligosaccharide of Francisella tularensis DO - 10.1021/ja306274v AU - Boltje, Thomas J. AU - Zhong, Wei AU - Park, Jin AU - Wolfert, Margreet A. AU - Chen, Wangxue AU - Boons, Geert-jan T2 - Journal of the American Chemical Society SN - 0002-7863 SN - 1520-5126 VL - 134 IS - 34 SP - 14255 EP - 14262 AB - Francisella tularensis, which is a Gram negative bacterium that causes tularemia, has been classified by the Center for Disease Control and Prevention (CDC) as a category A bioweapon. The development of vaccines, immunotherapeutics, and diagnostics for F. tularensis requires a detailed knowledge of the saccharide structures that can be recognized by protective antibodies. We have synthesized the inner core region of the lipopolysaccharide (LPS) of F. tularensis to probe antigenic responses elicited by a live and subunit vaccine. The successful preparation of the target compound relied on the use of a disaccharide which was modified by the orthogonal protecting groups diethylisopropylsilyl (DEIPS), 2-naphthylmethyl (Nap), allyl ether (All), and levulinoyl (Lev) ester. The ability to remove the protecting groups in different orders made it possible to establish the optimal glycosylations sequence to prepare a highly crowded 1,2,3-cis configured branching point. A variety of different methods were exploited to control anomeric selectivities of the glycosylations. A comparison of the ¹H NMR spectra of isolated material and the synthetic derivative confirmed the reported structural assignment of the inner core oligosaccharide of F. tularensis. The observation that immunizations with LPS lead to antibody responses to the inner core saccharides provides an impetus to further explore this compound as a vaccine candidate. DA - 2012/08/29 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fd133b22-6eeb-4650-b56f-68cce9a73b4b ER - TY - JOUR TI - Four-wave mixing in carbon nanotube-coated optical fiber gratings DO - 10.1063/1.3687170 AU - Shao, Li-Yang AU - Jakubinek, Michael B. AU - Sun, Tingting AU - Simard, Benoit AU - Albert, Jacques T2 - Applied Physics Letters SN - 0003-6951 VL - 100 IS - 071108 AB - The observation of four-wave mixing(FWM) in single-walled carbon nanotubes(SWCNTs) deposited around a tilted fiber Bragg grating (TFBG) has been demonstrated. A thin, floating SWCNTfilm is manually wrapped around the outer cladding of the fiber and FWM occurs between two core-guided laser signals by TFBG-induced interaction of the core mode and cladding modes. The effective nonlinear coefficient is calculated to be 1.8 × 103 W−¹ Km−¹. The wavelength of generated idlers is tunable with a range of 7.8 nm. DA - 2012/02/16 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e29a602d-e63a-4967-8dc5-20da39fe74ac ER - TY - JOUR TI - The effect of In-flush on the optical anisotropy of InAs/GaAs quantum dots DO - 10.1063/1.3681329 AU - Molas, M. AU - Gołasa, K. AU - Kuldová, K. AU - Borysiuk, J. AU - Babiński, A. AU - Lapointe, J. AU - Wasilewski, Z. R. T2 - Journal of Applied Physics SN - 0021-8979 VL - 111 IS - 3 SP - 033510 AB - The effect of the In-flush technique on the optical anisotropy of InAs/GaAs quantum dots(QDs) has been investigated. The anisotropy was deduced from low temperature microluminescence measurements of the splitting of the emission lines related to single neutral excitons confined to the QDs. It was found that the anisotropy was significantly smaller in a structure grown by the In-flush technique as compared to a structure grown without this procedure. It is proposed that this anisotropy reduction is due to the reduction in the strain generated within the GaAs barrier when using the In-flush procedure. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 52a4c7a9-3513-462e-a2a6-8a0dd7f5af87 ER - TY - JOUR TI - A Convenient Method for Preparing Alkyl-Functionalized Silicon Nanocubes DO - 10.1021/ja3061497 AU - Yang, Zhenyu AU - Dobbie, Alexander R. AU - Cui, Kai AU - Veinot, Jonathan G. C. T2 - Journal of the American Chemical Society SN - 0002-7863 SN - 1520-5126 VL - 134 IS - 34 SP - 13958 EP - 13961 AB - The first solid-state synthesis of diamond structure silicon nanocube structures with edge lengths of 8–15 nm is reported. It is well-established that controlled high-temperature processing of hydrogen silsesquioxane produces exceptionally well-defined pseudospherical silicon nanocrystals. However, only a small number of accounts outlining shape-controlled synthesis have appeared. We report here that, upon prolonged annealing in an oxide matrix, nanocrystal surfaces thermodynamically self-optimize, yielding particles with cubic geometries. Surface functionalization of the resulting nanocubes is readily achieved via thermal hydrosilylation. Discussion will include description of the synthetic procedure, comprehensive material characterization, and the factors that lead to the formation of cubic structures. DA - 2012/08/29 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2ee0fbc2-cfa4-4b14-ac48-7a5732a49774 ER - TY - JOUR TI - Spatially resolved raman spectroelectrochemistry of solid-state polythiophene/viologen memory devices DO - 10.1021/ja304458s AU - Kumar, Rajesh AU - Pillai, Rajesh G. AU - Pekas, Nikola AU - Wu, Yiliang AU - McCreery, Richard L. T2 - Journal of the American Chemical Society SN - 0002-7863 SN - 1520-5126 VL - 134 IS - 36 SP - 14869 EP - 14876 AB - A three terminal molecular memory device was monitored with in situ Raman spectroscopy during bias-induced switching between two metastable states having different conductivity. The device structure is similar to that of a polythiophene field effect transistor, but ethylviologen perchlorate was added to provide a redox counter-reaction to accompany polythiophene redox reactions. The conductivity of the polythiophene layer was reversibly switched between high and low conductance states with a “write/erase” (W/E) bias, while a separate readout circuit monitored the polymer conductance. Raman spectroscopy revealed reversible polythiophene oxidation to its polaron form accompanied by a one-electron viologen reduction. “Write”, “read”, and “erase” operations were repeatable, with only minor degradation of response after 200 W/E cycles. The devices exhibited switching immediately after fabrication and did not require an “electroforming” step required in many types of memory devices. Spatially resolved Raman spectroscopy revealed polaron formation throughout the polymer layer, even away from the electrodes in the channel and drain regions, indicating that thiophene oxidation “propagates” by growth of the conducting polaron form away from the source electrode. The results definitively demonstrate concurrent redox reactions of both polythiophene and viologen in solid-state devices and correlate such reactions with device conductivity. The mechanism deduced from spectroscopic and electronic monitoring should guide significant improvements in memory performance. DA - 2012/09/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e1b1f52b-470d-4fbb-911c-0f2a45f23548 ER - TY - JOUR TI - Quantum confinement in Si and Ge nanostructures DO - 10.1063/1.3680884 AU - Barbagiovanni, E. G. AU - Lockwood, D. J. AU - Simpson, P. J. AU - Goncharova, L. V. T2 - Journal of Applied Physics SN - 00218979 VL - 111 IS - 3 SP - 034307 AB - We apply perturbative effective mass theory as a broadly applicable theoretical model for quantum confinement (QC) in all Si and Genanostructures including quantum wells(QWs), wires (Q-wires), and dots(QDs). Within the limits of strong, medium, and weak QC, valence and conduction band edge energy levels (VBM and CBM) were calculated as a function of QD diameters, QW thicknesses, and Q-wire diameters. Crystalline and amorphous quantum systems were considered separately. Calculated band edge levels with strong, medium, and weak QC models were compared with experimental VBM and CBM reported from X-ray photoemission spectroscopy (XPS), X-ray absorption spectroscopy (XAS), or photoluminescence(PL). Experimentally, the dimensions of the nanostructures were determined directly, by transmission electron microscopy(TEM), or indirectly, by x-ray diffraction (XRD) or by XPS. We found that crystalline materials are best described by a medium confinement model, while amorphous materials exhibit strong confinement regardless of the dimensionality of the system. Our results indicate that spatial delocalization of the hole in amorphous versus crystalline nanostructures is the important parameter determining the magnitude of the band gap expansion, or the strength of the quantum confinement. In addition, the effective masses of the electron and hole are discussed as a function of crystallinity and spatial confinement. DA - 2012/02/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8bddb147-0a91-4ab6-8a7b-29539bd35b1a ER - TY - JOUR TI - 3D hydraulic model studies of pipeline secondary stabilization measures AU - Baker, Scott AU - Cornett, Andrew AU - Knox, Paul T2 - Coastlab 2012 : 4th International Conference on the Application of Physical Modelling to Port and Coastal Protection Book of Abstracts T3 - Coastlab 2012 : 4th International Conference on the Application of Physical Modelling to Port and Coastal Protection, Sept. 17–20, 2012, Ghent, Belgium AB - A 3D physical modelling campaign has been conducted to support the efficient and reliable design of secondary stabilization measures for subsea pipelines to be installed as part of the Browse LNG project. Many different secondary stabilization designs were assessed including static and dynamically re-shaping rock berms, gravity anchors, and V-shaped trenches. Modelled rock berm structures were constructed underwater to simulate prototype construction by fallpipe. This study generated a large amount of data and new information concerning the behaviour and reliability of pipeline stabilization measures in shallow water under extreme short-crested waves and currents. DA - 2012/10/01 PY - 2012 PB - Academia Publishing LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 45349460-4e14-45ef-bf00-432d65ffabff ER - TY - JOUR TI - Cage occupancies in the high pressure structure H methane hydrate: A neutron diffraction study DO - 10.1063/1.3679875 AU - Tulk, C. A. AU - Klug, D. D. AU - Dos Santos, A. M. AU - Karotis, G. AU - Guthrie, M. AU - Molaison, J. J. AU - Pradhan, N. T2 - The Journal of Chemical Physics SN - 0021-9606 VL - 136 IS - 5 SP - 054502 AB - A neutron diffraction study was performed on the CD4 : D2O structure H clathrate hydrate to refine its CD4 fractional cage occupancies. Samples of ice VII and hexagonal (sH) methane hydrate were produced in a Paris–Edinburgh press and in situneutron diffraction data collected. The data were analyzed with the Rietveld method and yielded average cage occupancies of 3.1 CD4 molecules in the large 20-hedron (5^12 6^8) cages of the hydrate unit cell. Each of the pentagonal dodecahedron (5^12) and 12-hedron (4^3 5^6 6^3) cages in the sH unit cell are occupied with on average 0.89 and 0.90 CD4 molecules, respectively. This experiment avoided the co-formation of Ice VI and sH hydrate, this mixture is more difficult to analyze due to the proclivity of ice VI to form highly textured crystals, and overlapping Bragg peaks of the two phases. These results provide essential information for the refinement of intermolecular potential parameters for the water–methane hydrophobic interaction in clathrate hydrates and related dense structures. DA - 2012/02/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d4c10cd3-6808-4296-a598-28521ce79527 ER - TY - JOUR TI - Thermo-mechanical sensitivity calibration of nanotorsional magnetometers DO - 10.1063/1.3676231 AU - Losby, Joseph AU - Burgess, Jacob A. J. AU - Diao, Zhu AU - Fortin, David C. AU - Hiebert, Wayne K. AU - Freeman, Mark R. T2 - Journal of Applied Physics SN - 00218979 VL - 111 IS - 7 SP - 07D305 AB - We report on the fabrication of sensitive nanotorsional resonators, which can be utilized as magnetometers for investigating the magnetization dynamics in small magnetic elements. The thermo-mechanical noise is calibrated with the resonator displacement in order to determine the ultimate mechanical torque sensitivity of the magnetometer. DA - 2012/03/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 06be33a1-ade5-4840-9786-737dff1b3b7c ER - TY - JOUR TI - Ultraviolet ZnSe1–xSx gradient-alloyed nanocrystals via a noninjection approach DO - 10.1021/am3009828 AU - Yu, Kui AU - Hrdina, Amy AU - Ouyang, Jianying AU - Kingston, David AU - Wu, Xiaohua AU - Leek, Donald M. AU - Liu, Xiangyang AU - Li, Chunsheng T2 - ACS Applied Materials and Interfaces SN - 1944-8244 SN - 1944-8252 VL - 4 IS - 8 SP - 4302 EP - 4311 KW - alloyed ZnSeS nanocrystals; colloidal quantum dots; photoluminescent; diphenylphosphine; noninjection approach AB - Highly emissive ultraviolet ZnSeS nanocrystals (NCs), with a core–shell-like structure, were designed and synthesized via a one-step noninjection approach in 1-octadecene (ODE). These ultraviolet ZnSeS NCs exhibit bright bandgap emission with high color purity and little trap emission. With full width at half-maximum (fwhm) of 21 nm only, photoluminescent (PL) quantum yield (QY) of 60% was estimated for one ensemble dispersed in toluene exhibiting bandgap absorption peaking at 380 nm and bandgap emission at 389 nm. These alloyed ZnSeS NCs present a cubic crystal structure consisting of a Se-rich core and a S-rich shell. Such a gradiently alloyed structure was suggested by our investigation on the temporal evolution of optical properties of the growing ZnSeS NCs monitored from 80 to 300 °C, together with structural and compositional characterization performed with XRD, XPS, EDX, and TEM. This newly developed one-step noninjection approach was achieved with zinc oleate (Zn(OA)2), diphenylphosphine selenide (SeDPP), and diphenylphosphine sulfide (SDPP) as Zn, Se, and S precursors, respectively. ZnSe monomers mainly participated in nucleation at 120 °C, while both ZnSe and ZnS monomers contributed to NC formation in later growth stages (160 °C and higher). 31P NMR study demonstrates that SeDPP is more reactive than SDPP toward Zn(OA)2, and also supports such a model proposed on the combination of ZnSe and ZnS monomers leading to nucleation/growth of ZnSeS alloyed NCs. The present study offers conceptual methodology to various highly photoluminescent alloyed NCs with high quality, high particle yield, and high synthetic reproducibility. DA - 2012/08/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b0f73fb5-381d-4b11-ba12-5b63c66ca781 ER - TY - JOUR TI - Andromeda and the Milky Way: twin sisters, distant relations, or strangers in the night? DO - 10.1051/epjconf/20121901003 AU - McConnachie, A. AU - Richardson, J. AU - Mackey, D. AU - PAndAS collaboration T2 - EPJ web of conferences: assembling the puzzle of the Milky Way T2 - The European Physical Journal; 19 T3 - Assembling the Puzzle of the Milky Way, April 18-22, 2011, Le Grand-Bornand, France SN - 2100-014X SN - 978-2-7598-0718-5 SP - 01003 AB - I summarize some recent key results from the Pan-Andromeda Archaeological Survey (PAndAS), in particular showing how recent discoveries in and around M31 compare to the known structure of the Milky Way and its satellite population. DA - 2012/02/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f6acb726-7d06-4ab8-873b-da8c7d7f6c5a ER - TY - JOUR TI - Multiple H 2 Occupancy of Cages of Clathrate Hydrate under Mild Conditions DO - 10.1021/ja303222u AU - Lu, Hailong AU - Wang, Jianwei AU - Liu, Changling AU - Ratcliffe, Christopher I. AU - Becker, Udo AU - Kumar, Rajnish AU - Ripmeester, John T2 - Journal of the American Chemical Society SN - 0002-7863 SN - 1520-5126 VL - 134 IS - 22 SP - 9160 EP - 9162 AB - Experiments were carried out by reacting H2 gas with N2 hydrate at a temperature of 243 K and a pressure of 15 MPa. The characterizations of the reaction products indicated that multiple H2 molecules can be loaded into both large and small cages of structure II clathrate hydrates. The realization of multiple H2 occupancy of hydrate cages under moderate conditions not only brings new insights into hydrogen clathrates but also refreshes the perspective of clathrate hydrates as hydrogen storage media. DA - 2012/06/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b9e3d0cf-feb3-41b4-b605-ca165c9f6031 ER - TY - JOUR TI - Organic nanostructures on hydrogen-terminated silicon report on electric field modulation of dangling bond charge state DO - 10.1021/ja3017208 AU - Ryan, Peter M. AU - Livadaru, Lucian AU - Dilabio, Gino A. AU - Wolkow, Robert A. T2 - Journal of the American Chemical Society SN - 0002-7863 SN - 1520-5126 VL - 134 IS - 29 SP - 12054 EP - 12063 AB - We pursue dynamic charge and occupancy modulation of silicon dangling bond sites on H–Si(100)-2 × 1 with a biased scanning tunneling microscope tip and demonstrate that the reactivity and mechanism of product formation of cyclobutylmethylketone (CBMK) on the surface at the active sites may be thus spatially regulated. Reactivity is observed to be dependent on the polarity between tip and surface while the area over which reactivity modulation is established scales according to the dopant concentration in the sample. We account for these observations with examination of the competition kinetics applicable to the CBMK/H–Si reaction and determine how said kinetics are affected by the charge state of DB sites associated with reaction initiation and propagation. Our experiments demonstrate a new paradigm in lithographic control of a self-assembly process on H–Si and reveal a variant to the well-known radical mediated chain reaction chemistry applicable to the H–Si surface where self-assembly is initiated with dative bond formation between the molecule and a DB site. DA - 2012/07/25 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7b0cfdf8-c7c6-4acc-8ad0-7ba13dce1245 ER - TY - JOUR TI - A DEBRIS disk around the planet hosting M-star GJ 581 spatially resolved with Herschel DO - 10.1051/0004-6361/201220325 AU - Lestrade, J.-F. AU - Matthews, B. C. AU - Sibthorpe, B. AU - Kennedy, G. M. AU - Wyatt, M. C. AU - Bryden, G. AU - Greaves, J. S. AU - Thilliez, E. AU - Moro-Martín, A. AU - Booth, M. AU - Dent, W. R. F. AU - Duchêne, G. AU - Harvey, P. M. AU - Horner, J. AU - Kalas, P. AU - Kavelaars, J. J. AU - Phillips, N. M. AU - Rodriguez, D. R. AU - Su, K. Y. L. AU - Wilner, D. J. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 548 SP - A86 AB - Debris disks have been found primarily around intermediate and solar mass stars (spectral types A–K) but rarely around low mass M-type stars. We have spatially resolved a debris disk around the remarkable M3-type star GJ 581 hosting multiple planets using deep PACS images at 70, 100 and 160 μm as part of the DEBRIS Program on the Herschel Space Observatory. This is the second spatially resolved debris disk found around an M-type star, after the one surrounding the young star AU Mic (12 Myr). However, GJ 581 is much older (2–8 Gyr), and is X-ray quiet in the ROSAT data. We fit an axisymmetric model of the disk to the three PACS images and found that the best fit model is for a disk extending radially from 25 ± 12 AU to more than 60 AU. Such a cold disk is reminiscent of the Kuiper belt but it surrounds a low mass star (0.3 M⊙) and its fractional dust luminosity Ldust/L∗ of ~ 10-4 is much higher. The inclination limits of the disk found in our analysis make the masses of the planets small enough to ensure the long-term stability of the system according to some dynamical simulations. The disk is collisionally dominated down to submicron-sized grains and the dust cannot be expelled from the system by radiation or wind pressures because of the low luminosity and low X-ray luminosity of GJ 581. We suggest that the correlation between low-mass planets and debris disks recently found for G-type stars also applies to M-type stars. Finally, the known planets, of low masses and orbiting within 0.3 AU from the star, cannot dynamically perturb the disk over the age of the star, suggesting that an additional planet exists at larger distance that is stirring the disk to replenish the dust. DA - 2012/11/27 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b4733b92-1f85-4715-9e9d-9f6a528b1918 ER - TY - JOUR TI - On the incidence of weak magnetic fields in DA white dwarfs DO - 10.1051/0004-6361/201219829 AU - Landstreet, J. D. AU - Bagnulo, S. AU - Valyavin, G. G. AU - Fossati, L. AU - Jordan, S. AU - Monin, D. AU - Wade, G. A. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 545 SP - A30 KW - white dwarfs, stars: magnetic field AB - Context. About 10% of white dwarfs have magnetic fields with strength in the range between about 105 and 5 × 108 G. It is not known whether the remaining white dwarfs are not magnetic, or if they have magnetic fields too weak to be detected with the techniques adopted in the large surveys. Information is particularly lacking for the cooler (and generally fainter) white dwarfs. Aims. We describe the results of the first survey specifically devised to clarify the detection frequency of kG-level magnetic fields in cool DA white dwarfs. Methods. Using the FORS1 instrument of the ESO VLT, we have obtained Balmer line circular spectropolarimetric measurements of a small sample of cool (DA6 – DA8) white dwarfs. Using FORS and UVES archive data, we have also revised numerous white dwarf field measurements previously published in the literature. Results. We have discovered an apparently constant longitudinal magnetic field of ~9.5 kG in the DA6 white dwarf WD 2105−820. This star is the first weak-field white dwarf that has been observed sufficiently to roughly determine the characteristics of its field. The available data are consistent with a simple dipolar morphology with magnetic axis nearly parallel to the rotation axis, and a polar strength of ≃ 56 kG. Our re-evaluation of the FORS archive data for white dwarfs indicates that longitudinal magnetic fields weaker than 10 kG have previously been correctly identified in at least three white dwarfs. However, for one of these three weak-field stars (WD 2359−434), UVES archive data show a ~100 kG mean field modulus. Either at the time of the FORS observations the star’s magnetic field axis was nearly perpendicular to the line of sight, or the star’s magnetic field has rather complex structure. Conclusions. We find that the probability of detecting a field of kG strength in a DA white dwarf is of the order of 10% for each of the cool and hot DA stars. If there is a lower cutoff to field strength in white dwarfs, or a field below which all white dwarfs are magnetic, the current precision of measurements is not yet sufficient to reveal it. DA - 2012/08/31 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e9cc8f44-1eb8-4335-97b3-d924ffd810be ER - TY - JOUR TI - A catalogue of Paschen-line profiles in standard stars DO - 10.1051/0004-6361/201219804 AU - Huang, W. AU - Wallerstein, G. AU - Stone, M. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 547 SP - A62 AB - We have assembled an atlas of line profiles of the Paschen Delta (Pδ) line at 10 049 Å for the use of stellar modelling. For a few stars we have substituted the Paschen Gamma (Pγ) line at 10 938 Å because the Pδ line blends with other features. Most of the targets are standard stars of spectral types from B to M. A few metal-poor stars have been included. For many of the stars we have also observed the Hydrogen Alpha (Hα) line so as to compare the profiles of lines originating from the meta-stable n = 2 level with lines originating from the n = 3 level. The greatest difference in line profile is found for high luminosity and cool stars where the departures from local thermodynamic equilibrium (LTE) in the population of the n = 2 level is expected to be the greatest. For a few stars, sample line profiles have been calculated in the LTE approximation to demonstrate the usefulness of the tabulated and displayed catalogue. DA - 2012/10/29 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c810e5f8-5b06-4daf-a1b9-4ad9dc6625eb ER - TY - JOUR TI - Unraveling the mechanism of catalytic reduction of O2 by microperoxidase-11 adsorbed within a transparent 3D-nanoporous ITO film DO - 10.1021/ja301193s AU - Renault, Christophe AU - Andrieux, Claude P. AU - Tucker, Ryan T. AU - Brett, Michael J. AU - Balland, Véronique AU - Limoges, Benoît T2 - Journal of the American Chemical Society SN - 0002-7863 SN - 1520-5126 VL - 134 IS - 15 SP - 6834 EP - 6845 AB - Nanoporous films of indium tin oxide (ITO), with thicknesses ranging from 250 nm to 2 μm, were prepared by Glancing Angle Deposition (GLAD) and used as highly sensitive transparent 3D-electrodes for quantitatively interrogating, by time-resolved spectroelectrochemistry, the reactivity of microperoxidase-11 (MP-11) adsorbed within such films. The capacitive current densities of these 3D-electrodes as well as the amount of adsorbed MP-11 were shown to be linearly correlated to the GLAD ITO film thickness, indicating a homogeneous distribution of MP-11 across the film as well as homogeneous film porosity. Under saturating adsorption conditions, MP-11 film concentration as high as 60 mM was reached. This is equivalent to a stack of 110 monolayers of MP-11 per micrometer film thickness. This high MP-11 film loading combined with the excellent ITO film conductivity has allowed the simultaneous characterization of the heterogeneous one-electron transfer dynamics of the MP-11 FeIII/FeII redox couple by cyclic voltammetry and cyclic voltabsorptometry, up to a scan rate of few volts per second with a satisfactory single-scan signal-to-noise ratio. The potency of the method to unravel complex redox coupled chemical reactions was also demonstrated with the catalytic reduction of oxygen by MP-11. In the presence of O2, cross-correlation of electrochemical and spectroscopic data has allowed us to determine the key kinetics and thermodynamics parameters of the redox catalysis that otherwise could not be easily extracted using conventional protein film voltammetry. On the basis of numerical simulations of cyclic voltammograms and voltabsorptograms and within the framework of different plausible catalytic reaction schemes including appropriate approximations, it was shown possible to discriminate between different possible catalytic pathways and to identify the relevant catalytic cycle. In addition, from the best fits of simulations to the experimental voltammograms and voltabsorptograms, the partition coefficient of O2 for the ITO film as well as the values of two kinetic rate constants could be extracted. It was finally concluded that the catalytic reduction of O2 by MP-11 adsorbed within nanoporous ITO films occurs via a 2-electron mechanism with the formation of an intermediate FeIII–OOH adduct characterized by a decay rate of 11 s⁻¹. The spectroelectroanalytical strategy presented here opens new opportunities for characterizing complex redox-coupled chemical reactions not only with redox proteins, but also with redox biomimetic systems and catalysts. It might also be of great interest for the development and optimization of new spectroelectrochemical sensors and biosensors, or eventually new photoelectrocatalytic systems or biofuel cells. DA - 2012/04/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 31a6836b-99c3-4b8b-96da-e883aee6d06b ER - TY - JOUR TI - Herschel observations of B1-bS and B1-bN: two first hydrostatic core candidates in the Perseus star-forming cloud DO - 10.1051/0004-6361/201219501 AU - Pezzuto, S. AU - Elia, D. AU - Schisano, E. AU - Strafella, F. AU - Di Francesco, J. AU - Sadavoy, S. AU - André, P. AU - Benedettini, M. AU - Bernard, J. P. AU - Di Giorgio, A. M. AU - Facchini, A. AU - Hennemann, M. AU - Hill, T. AU - Könyves, V. AU - Molinari, S. AU - Motte, F. AU - Nguyen-Luong, Q. AU - Peretto, N. AU - Pestalozzi, M. AU - Polychroni, D. AU - Rygl, K. L. J. AU - Saraceno, P. AU - Schneider, N. AU - Spinoglio, L. AU - Testi, L. AU - Ward-Thompson, D. AU - White, G. J. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 547 SP - A54 AB - We report far-infrared Herschel observations obtained between 70 μm and 500 μm of two star-forming dusty condensations, [HKM99] B1-bS and [HKM99] B1-bN, in the B1 region of the Perseus star-forming cloud. In the western part of the Perseus cloud, B1-bS is the only source detected in all six PACS and SPIRE photometric bands, but it is not visible in the Spitzer map at 24 μm. B1-bN is clearly detected between 100 μm and 250 μm. We have fitted the spectral energy distributions of these sources to derive their physical properties, and find that a simple greybody model fails to reproduce the observed spectral energy distributions. At least a two-component model is required, consisting of a central source surrounded by a dusty envelope. The properties derived from the fit, however, suggest that the central source is not a Class 0 object. We then conclude that while B1-bS and B1-bN appear to be more evolved than a pre-stellar core, the best-fit models suggest that their central objects are younger than a Class 0 source. Hence, they may be good candidates to be examples of the first hydrostatic core phase. The projected distance between B1-bS and B1-bN is a few Jeans lengths. If their physical separation is close to this value, this pair would allow studying the mutual interactions between two forming stars at a very early stage of their evolution. DA - 2012/10/25 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 47d03dd6-bca6-4343-8fc6-e8d0597a4f99 ER - TY - JOUR TI - The spine of the swan: a Herschel study of the DR21 ridge and filaments in Cygnus X DO - 10.1051/0004-6361/201219429 AU - Hennemann, M. AU - Motte, F. AU - Schneider, N. AU - Didelon, P. AU - Hill, T. AU - Arzoumanian, D. AU - Bontemps, S. AU - Csengeri, T. AU - André, Ph. AU - Konyves, V. AU - Louvet, F. AU - Marston, A. AU - Men’shchikov, A. AU - Minier, V. AU - Nguyen Luong, Q. AU - Palmeirim, P. AU - Peretto, N. AU - Sauvage, M. AU - Zavagno, A. AU - Anderson, L. D. AU - Bernard, J.-Ph. AU - Di Francesco, J. AU - Elia, D. AU - Li, J. Z. AU - Martin, P. G. AU - Molinari, S. AU - Pezzuto, S. AU - Russeil, D. AU - Rygl, K. L. J. AU - Schisano, E. AU - Spinoglio, L. AU - Sousbie, T. AU - Ward-Thompson, D. AU - White, G. J. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 543 AB - In order to characterise the cloud structures responsible for the formation of high-mass stars, we present Herschel observations of the DR21 environment. Maps of the column density and dust temperature unveil the structure of the DR21 ridge and several connected filaments. The ridge has column densities higher than 10²³ cm-² over a region of 2.3 pc². It shows substructured column density profiles and branches into two major filaments in the north. The masses in the filaments range between 130 and 1400 M⊙, whereas the mass in the ridge is 15 000 M⊙. The accretion of these filaments onto the DR21 ridge, suggested by a previous molecular line study, could provide a continuous mass inflow to the ridge. In contrast to the striations seen in, e.g., the Taurus region, these filaments are gravitationally unstable and form cores and protostars. These coresformed in the filaments potentially fall into the ridge. Both inflow and collisions of cores could be important to drive the observed high-mass star formation. The evolutionary gradient of star formation running from DR21 in the south to the northern branching is traced by decreasing dust temperature. This evolution and the ridge structure can be explained by two main filamentary components of the ridge that merged first in the south. DA - 2012/06/27 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c74dfb44-3edb-4536-ae3c-3b4975c2ecaf ER - TY - JOUR TI - Globular cluster systems in fossil groups: NGC 6482, NGC 1132, and ESO 306-017 DO - 10.1051/0004-6361/201219285 AU - Alamo-Martínez, K. A. AU - West, M. J. AU - Blakeslee, J. P. AU - González-Lópezlira, R. A. AU - Jordán, A. AU - Gregg, M. AU - Côté, P. AU - Drinkwater, M. J. AU - Van den Bergh, S. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 546 AB - We study the globular cluster (GC) systems in three representative fossil group galaxies: the nearest (NGC 6482), the prototype (NGC 1132) and the most massive known to date (ESO 306-017). This is the first systematic study of GC systems in fossil groups. Using data obtained with the Hubble Space Telescope Advanced Camera for Surveys in the F475W and F850LP filters, we determine the GC color and magnitude distributions, surface number density profiles, and specific frequencies. In all three systems, the GC color distribution is bimodal, the GCs are spatially more extended than the starlight, and the red population is more concentrated than the blue. The specific frequencies seem to scale with the optical luminosities of the central galaxy and span a range similar to that of the normal bright elliptical galaxies in rich environments. We also analyze the galaxy surface brightness distributions to look for deviations from the best-fit Sérsic profiles; we find evidence of recent dynamical interaction in all three fossil group galaxies. Using X-ray data from the literature, we find that luminosity and metallicity appear to correlate with the number of GCs and their mean color, respectively. Interestingly, although NGC 6482 has the lowest mass and luminosity in our sample, its GC system has the reddest mean color, and the surrounding X-ray gas has the highest metallicity. DA - 2012/09/28 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : be1aa688-3c15-4cac-9428-e0418f5128a5 ER - TY - JOUR TI - The molecular gas content of the Pipe Nebula DO - 10.1051/0004-6361/201219240 AU - Duarte-Cabral, A. AU - Chrysostomou, A. AU - Peretto, N. AU - Fuller, G. A. AU - Matthews, B. AU - Schieven, G. AU - Davis, G. R. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 543 AB - Context. Star forming regions may share many characteristics, but the specific interplay between gravity, magnetic fields, large-scale dynamics, and protostellar feedback will have an impact on the star formation history of each region. The importance of feedback from outflows is a particular subject to debate, as we are yet to understand the details of their impact on clouds and star formation. Aims. The Pipe Nebula is a nearby molecular cloud hosting the B59 region as its only active star-forming clump. This paper focuses on the global dynamics of B59, its temperature structure, and its outflowing gas, with the goal of revealing the local and global impact of the protostellar outflows. Methods. Using HARP at the James Clerk Maxwell Telescope, we have mapped the B59 region in the J = 3 → 2 transition of 12CO to study the kinematics and energetics of the outflows, and the same transitions of 13CO and C18O to study the overall dynamics of the ambient cloud, the physical properties of the gas, and the hierarchical structure of the region. Results. The B59 region has a total of ~30 M⊙ of cold and quiescent material, mostly gravitationally bound, with narrow line widths throughout. Such low levels of turbulence in the non-star-forming regions within B59 are indicative of the intrinsic initial conditions of the cloud. On the other hand, close to the protostars the impact of the outflows is observed as a localised increase of both C18O line widths from ~0.3 km s-¹ to ~1 km s-¹, and 13CO excitation temperatures by ~2–3 K. The impact of the outflows is also evident in the low column density material which shows signs of being shaped by the outflow bow shocks as they pierce their way out of the cloud. Much of this structure is readily apparent in a dendrogram analysis of the cloud and demonstrates that when decomposing clouds using such techniques a careful interpretation of the results is needed. Conclusions. The low mass of B59 together with its intrinsically quiescent gas and small number of protostars, allows the identification of specific regions where the outflows from the embedded sources interact the dense gas. Our study suggests that outflows are an important mechanism for injecting and sustaining supersonic turbulence at sub-parsec size scales. We find that less than half of the outflow energy is deposited as turbulent energy of the gas, however this turbulent energy is sufficient to slow down the collapse of the region. DA - 2012/07/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7cc6c46a-92e6-487c-9f76-e104ec62d55b ER - TY - JOUR TI - Age and helium content of the open cluster NGC  6791 from multiple eclipsing binary members DO - 10.1051/0004-6361/201219196 AU - Brogaard, K. AU - Vandenberg, D. A. AU - Bruntt, H. AU - Grundahl, F. AU - Frandsen, S. AU - Bedin, L. R. AU - Milone, A. P. AU - Dotter, A. AU - Feiden, G. A. AU - Stetson, P. B. AU - Sandquist, E. AU - Miglio, A. AU - Stello, D. AU - Jessen-Hansen, J. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 543 AB - Context. Models of stellar structure and evolution can be constrained by measuring accurate parameters of detached eclipsing binaries in open clusters. Multiple binary stars provide the means to determine helium abundances in these old stellar systems, and in turn, to improve estimates of their age. Aims. In the first paper of this series, we demonstrated how measurements of multiple eclipsing binaries in the old open cluster NGC 6791 sets tighter constraints on the properties of stellar models than has previously been possible, thereby potentially improving both the accuracy and precision of the cluster age. Here we add additional constraints and perform an extensive model comparison to determine the best estimates of the cluster age and helium content, employing as many observational constraints as possible. Methods. We improve our photometry and correct empirically for differential reddening effects. We then perform an extensive comparison of the new colour-magnitude diagrams (CMDs) and eclipsing binary measurements to Victoria and DSEP isochrones in order to estimate cluster parameters. We also reanalyse a spectrum of the star 2–17 to improve [Fe/H] constraints. Results. We find a best estimate of the age of ~8.3 Gyr for NGC 6791 while demonstrating that remaining age uncertainty is dominated by uncertainties in the CNO abundances. The helium mass fraction is well constrained at Y = 0.30±0.01 resulting in ΔY/ΔZ ~  1.4 assuming that such a relation exists. During the analysis we firmly identify blue straggler stars, including the star 2–17, and find indications for the presence of their evolved counterparts. Our analysis supports the RGB mass-loss found from asteroseismology and we determine precisely the absolute mass of stars on the lower RGB, MRGB = 1.15±0.02 M⊙. This will be an important consistency check for the detailed asteroseismology of cluster stars. Conclusions. Using multiple, detached eclipsing binaries for determining stellar cluster ages, it is now possible to constrain parameters of stellar models, notably the helium content, which were previously out of reach. By observing a suitable number of detached eclipsing binaries in several open clusters, it will be possible to calibrate the age-scale and the helium enrichment parameter Δ Y/Δ Z, and provide firm constraints that stellar models must reproduce. DA - 2012/07/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a9980e3d-6e6d-408f-b696-e2376303d85f ER - TY - JOUR TI - A wide-field near-infrared H₂ 2.122 μm line survey of the Braid Nebula star formation region in Cygnus OB7 DO - 10.1051/0004-6361/201219124 AU - Khanzadyan, T. AU - Davis, C. J. AU - Aspin, C. AU - Froebrich, D. AU - Smith, M. D. AU - Magakian, T. Yu. AU - Movsessian, T. AU - Moriarty-Schieven, G. H. AU - Nikogossian, E. H. AU - Pyo, T.-S. AU - Beck, T. L. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 542 SP - A111 SP - A111-1 EP - A111-36 AB - Context. Outflows and jets are the first signposts of ongoing star formation processes in any molecular cloud, yet their study in optical bands provides limited results due to the large extinction present. Near-infrared unbiased wide-field observations in the H2 1−0 S(1) line at 2.122 μm alleviates the problem, enabling us to detect more outflows and trace them closer to their driving sources. Aims. As part of a large-scale multi-waveband study of ongoing star formation in the Braid Nebula star formation region, we focus on a one square degree region that includes Lynds Dark Nebula 1003 and 1004. Our goal is to find all of the near-infrared outflows, uncover their driving sources and estimate their evolutionary phase. Methods. We use near-infrared wide-field observations obtained with WFCAM on UKIRT, in conjunction with previously-published optical and archival MM data, to search for outflows and identify their driving sources; we subsequently use colour − colour analysis to determine the evolutionary phase of each source. Results. Within a one square degree field we have identified 37 complex MHOs, most of which are new. After combining our findings with other wide-field, multi-waveband observations of the same region we were able to discern 28 outflows and at least 18 protostars. Our analysis suggests that these protostars are younger and/or more energetic than those of the Taurus-Auriga region. The outflow data enable us to suggest connection between outflow ejection and repetitive FU Ori outburst events. We also find that star formation progresses from W to E across the investigated region. DA - 2012/06/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 71613e19-6d3f-42a2-a631-dc1c386222ba ER - TY - JOUR TI - New insights into the mechanism of amine/nitroxide cycling during the hindered amine light stabilizer inhibited oxidative degradation of polymers DO - 10.1021/ja3006379 AU - Gryn’ova, Ganna AU - Ingold, K. U. AU - Coote, Michelle L. T2 - Journal of the American Chemical Society SN - 0002-7863 SN - 1520-5126 VL - 134 IS - 31 SP - 12979 EP - 12988 AB - High-level ab initio molecular orbital theory calculations are used to identify the origin of the remarkably high inhibition stoichiometric factors exhibited by dialkylamine-based radical-trapping antioxidants. We have calculated the free energy barriers and reaction energies at 25, 80, and 260 °C in the gas phase and in aqueous solution for a broad range of reactions that might, potentially, be involved in amine/nitroxide cycling, as well as several novel pathways proposed as part of the present work, including that of N-alkyl hindered amine light stabilizer activation. We find that most of the literature nitroxide regeneration cycles should be discarded on either kinetic or thermodynamic grounds; some are even inconsistent with existing experimental observations. We therefore propose a new mechanistic cycle that relies on abstraction of a β-hydrogen atom from an alkoxyamine (R¹R²NOCHR³R⁴). Our results suggest that this cycle is energetically feasible for a range of substrates and provides an explanation for previously misinterpreted or unexplained experimental results. We also explore alternative mechanisms for amine/nitroxide cycling for cases where the alkoxyamines do not possess an abstractable β-hydrogen. DA - 2012/08/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 109a7c2b-8af6-400f-9b80-116a54aacccb ER - TY - JOUR TI - The composite-spectrum binary hypothesis does not explain the λ Bootis stars DO - 10.1051/0004-6361/201219112 AU - Griffin, R. E. AU - Gray, R. O. AU - Corbally, C. J. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 547 AB - The existence of the λ Boo type as a class of chemically-peculiar stars in its own right has taxed numerous researchers, and has challenged spectroscopists to produce a model which is plausible, comprehensive and predictive. Stars which are recognized as members of the λ Boo class have late-B to early-F spectral types, and exhibit (often substantially) low abundances of Fe-peak elements although elements such as C, N, O and S may have more nearly solar abundances. Since less than 2% of objects within the relevant spectral-type domain appear to be λ Boo stars their existence has demanded rather special conditions, and has triggered opinion that this group may not in fact exist but that each case can be explained as an unrecognized binary. In this paper we examine those claims by monitoring 10 stars, listed in the literature as possible λ Boo stars but said to be “likely candidates” for composite-spectrum binaries, by employing high-dispersion spectroscopy in an intermittent observing programme designed to reveal the sort of line-profile changes that should be detectable if each object were really a pair of similar stars in an SB2 system. We also monitor two other stars: HR 7903, said to be a binary (but is more like an Ap star), and λ Boo itself. The sample includes 1 possible, 1 marginal and 4 definite λ Boo classifications. In addition, we derive the physical properties of the 12 stars by photometric and spectroscopic synthesis, and measure their radial velocities. Three of the sample show small line-profile variations, but not of the sort that can be attributed to the presence of a companion star; they are the suspected Ap star HR 7903, HR 6878 (which exhibits spectrum peculiarities very similar to those of HR 7903 but has not previously been classified as Bp or Ap), and λ Aql, whose rapid spectrum variations resemble those observed in spotted or CP stars. None of the stars shows any evidence to suggest that it could be a composite-spectrum binary. DA - 2012/10/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : beabce89-6ace-4c0c-acdf-d75ca3d2ff83 ER - TY - JOUR TI - Systematic study of compositional and synthetic control of vacancy and magnetic ordering in oxygen-deficient perovskites Ca2Fe2–xMnxO5+y and CaSrFe2–xMnxO5+y(x= 1/2, 2/3, and 1;y= 0–1/2) DO - 10.1021/ja210985t AU - Ramezanipour, Farshid AU - Greedan, John E. AU - Cranswick, Lachlan M. D. AU - Garlea, V. Ovidiu AU - Donaberger, Ronald L. AU - Siewenie, Joan T2 - Journal of the American Chemical Society SN - 1520-5126 VL - 134 IS - 6 SP - 3215 EP - 3227 AB - Ten compounds belonging to the series of oxygen-deficient perovskite oxides Ca2Fe2–xMnxO5 and CaSrFe2–xMnxO5+y, where x = 1/2, 2/3, and 1 and y ≈ 0–0.5, were synthesized and investigated with respect to the ordering of oxygen vacancies on both local and long-range length scales and the effect on crystal structure and magnetic properties. For the set with y ≈ 0 the oxygen vacancies always order in the long-range sense to form the brownmillerite structure containing alternating layers of octahedrally and tetrahedrally coordinated cations. However, there is a change in symmetry from Pnma to Icmm upon substitution of Sr for one Ca for all x, indicating local Td chain (vacancy) disorder. In the special case of CaSrFeMnO5 the neutron diffraction peaks broaden, indicating only short-range structural order on a length scale of 160 Å. This reveals a systematic progression from Ca2FeMnO5 (Pnma, well-ordered tetrahedral chains) to CaSrFeMnO5 (Icmm, disordered tetrahedral chains, overall short-range order) to Sr2FeMnO5 (Pm3m, destruction of tetrahedral chains in a long-range sense). Systematic changes occur in the magnetic properties as well. While long-range antiferromagnetic order is preserved, the magnetic transition temperature, Tc, decreases for the same x when Sr substitutes for one Ca. A review of the changes in Tc for the series Ca2Fe2–xMxO5, taking into account the tetrahedral/octahedral site preferences for the various M3+ ions, leads to a partial understanding of the origin of magnetic order in these materials in terms of a layered antiferromagnetic model. While in all cases the preferred magnetic moment direction is (010) at low temperatures, there is a cross over for x = 0.5 to (100) with increasing temperature for both the Ca2Fe2–xMnxO5 and the CaSrFe2–xMnxO5 series. For the y > 0 phases, while a brownmillerite ordering of oxygen vacancies is preserved for the Ca2 phases, a disordered Pm3m cubic perovskite structure is always found when Sr is substituted for one Ca. Long-range magnetic order is also lost, giving way to spin glass or cluster-glass-like behavior below 50 K. For the x = 0.5 phase, neutron pair distribution function (NPDF) studies show a local structure related to brownmillerite ordering of oxygen vacancies. Neutron diffraction data at 3.8 K show a broad magnetic feature, incommensurate with any multiple of the chemical lattice, and with a correlation length (magnetic domain) of 6.7(4) Å. DA - 2012/02/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 30a42351-6746-4ba2-b9cf-d8cdbe22035c ER - TY - JOUR TI - Assembling photoluminescent silicon nanocrystals into periodic mesoporous organosilica DO - 10.1021/ja209532e AU - Guan, Min AU - Wang, Wendong AU - Henderson, Eric J. AU - Dag, Ömer AU - Kübel, Christian AU - Chakravadhanula, Venkata sai kiran AU - Rinck, Julia AU - Moudrakovski, Igor L. AU - Thomson, Jordan AU - Mcdowell, Jeffrey AU - Powell, Annie K. AU - Zhang, Haixia AU - Ozin, Geoffrey A. T2 - Journal of the American Chemical Society SN - 0002-7863 SN - 1520-5126 VL - 134 IS - 20 SP - 8439 EP - 8446 AB - A contemporary question in the intensely active field of periodic mesoporous organosilica (PMO) materials is how large a silsesquioxane precursor can be self-assembled under template direction into the pore walls of an ordered mesostructure. An answer to this question is beginning to emerge with the ability to synthesize dendrimer, buckyball, and polyhedral oligomeric silsesquioxane PMOs. In this paper, we further expand the library of large-scale silsesquioxane precursors by demonstrating that photoluminescent nanocrystalline silicon that has been surface-capped with oligo(triethoxysilylethylene), denoted as ncSi:(CH2CH2Si(OEt)3)nH, can be self-assembled into a photoluminescent nanocrystalline silicon periodic mesoporous organosilica (ncSi-PMO). A comprehensive multianalytical characterization of the structural and optical properties of ncSi-PMO demonstrates that the material gainfully combines the photoluminescent properties of nanocrystalline silicon with the porous structure of the PMO. This integration of two functional components makes ncSi-PMO a promising multifunctional material for optoelectronic and biomedical applications. DA - 2012/05/23 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 10687d38-0a1f-4340-a339-fed462daa109 ER - TY - JOUR TI - Toward a mechanistic understanding of exciton-mediated hydrosilylation on nanocrystalline silicon DO - 10.1021/ja208604r AU - Huck, Lawrence A. AU - Buriak, Jillian M. T2 - Journal of the American Chemical Society SN - 0002-7863 SN - 1520-5126 VL - 134 IS - 1 SP - 489 EP - 497 AB - White-light initiated hydrosilylation of nanocrystalline porous silicon was found to be far more efficient (in terms of both kinetics and yield) in the presence of electron-accepting molecules with suitably high reduction potentials, particularly halocarbons. It is known that absorption of visible light by nanocrystalline silicon results in the formation of excitons (electron/hole pairs) and that this exciton can be harnessed to drive a hydrosilylation reaction with an alkene; the Si–C bond forms as a result of attack of the π-electrons of the alkene on the positively charged holes. In order to better understand the white-light initiated mechanism through which this reaction takes place, and to compare with UV-mediated photoemission on Si(111)–H, a series of electron acceptors were screened for their effect on surface alkene hydrosilylation. A very strong correlation between reduction potentials (Ered) of the oxidant and reaction efficiency was observed, with a minimum “turn-on” Ered required for an increase to take place. The oxidant appears to accept, or remove, the electron from the nanocrystallite-bound exciton, favoring attack by the alkene on the positively charged Si nanocrystallite, leading to Si–C bond formation. Radical reactions were discounted for a number of reasons, including lack of effect of radical traps, no apparent Si–Cl bond formation, lack of oxidation of the surfaces, and others. Unlike with other oxidants such as nitro-aromatics, halocarbons do not cause additional surface reactions and promote very clean, fast, and selective hydrosilylation chemistry. DA - 2012/01/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 10aef643-307f-476b-956f-13c63db58aa0 ER - TY - JOUR TI - The M 16 molecular complex under the influence of NGC 6611 DO - 10.1051/0004-6361/201219009 AU - Hill, T. AU - Motte, F. AU - Didelon, P. AU - White, G. J. AU - Marston, A. P. AU - Nguyên Luong, Q. AU - Bontemps, S. AU - André, Ph. AU - Schneider, N. AU - Hennemann, M. AU - Sauvage, M. AU - Di Francesco, J. AU - Minier, V. AU - Anderson, L. D. AU - Bernard, J. P. AU - Elia, D. AU - Griffin, M. J. AU - Li, J. Z. AU - Peretto, N. AU - Pezzuto, S. AU - Polychroni, D. AU - Roussel, H. AU - Rygl, K. L. J. AU - Schisano, E. AU - Sousbie, T. AU - Testi, L. AU - Ward Thompson, D. AU - Zavagno, A. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 542 AB - We present Herschel images from the HOBYS key program of the Eagle Nebula (M 16) in the far-infrared and sub-millimetre, using the PACS and SPIRE cameras at 70 μm, 160 μm, 250 μm, 350 μm, 500 μm. M 16, home to the Pillars of Creation, is largely under the influence of the nearby NGC 6611 high-mass star cluster. The Herschel images reveal a clear dust temperature gradient running away from the centre of the cavity carved by the OB cluster. We investigate the heating effect of NGC 6611 on the entire M 16 star-forming complex seen by Herschel including the diffuse cloud environment and the dense filamentary structures identified in this region. In addition, we interpret the three-dimensional geometry of M 16 with respect to the nebula, its surrounding environment, and the NGC 6611 cavity. The dust temperature and column density maps reveal a prominent eastern filament running north-south and away from the high-mass star-forming central region and the NGC 6611 cluster, as well as a northern filament which extends around and away from the cluster. The dust temperature in each of these filaments decreases with increasing distance from the NGC 6611 cluster, indicating a heating penetration depth of ~10 pc in each direction in 3–6  ×  1022 cm-2 column density filaments. We show that in high-mass star-forming regions OB clusters impact the temperature of future star-forming sites, modifying the initialconditions for collapse and effecting the evolutionary criteria of protostars developed from spectral energy distributions. Possible scenarios for the origin of the morphology seen in this region are discussed, including a western equivalent to the eastern filament, which was destroyed by the creation of the OB cluster and its subsequent winds and radiation. DA - 2012/06/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 442ec488-1feb-4021-a342-c70467023fc5 ER - TY - JOUR TI - Transition state analysis of Vibrio cholerae sialidase-catalyzed hydrolyses of natural substrate analogues DO - 10.1021/ja208564y AU - Chan, Jefferson AU - Lewis, Andrew R. AU - Indurugalla, Deepani AU - Schur, Melissa AU - Wakarchuk, Warren AU - Bennet, Andrew J. T2 - Journal of the American Chemical Society SN - 0002-7863 SN - 1520-5126 VL - 134 IS - 8 SP - 3748 EP - 3757 AB - A series of isotopically labeled natural substrate analogues (phenyl 5-N-acetyl-α-d-neuraminyl-(2→3)-β-d-galactopyranosyl-(1→4)-1-thio-β-d-glucopyranoside; Neu5Acα2,3LacβSPh, and the corresponding 2→6 isomer) were prepared chemoenzymatically in order to characterize, by use of multiple kinetic isotope effect (KIE) measurements, the glycosylation transition states for Vibrio cholerae sialidase-catalyzed hydrolysis reactions. The derived KIEs for Neu5Acα2,3LacβSPh for the ring oxygen (18V/K), leaving group oxygen (°⁶V/K), C3-S deuterium (DV/KS) and C3-R deuterium (DV/KR) are 1.029 ± 0.002, 0.983 ± 0.001, 1.034 ± 0.002, and 1.043 ± 0.002, respectively. In addition, the KIEs for Neu5Acα2,6βSPh for C3-S deuterium (DV/KS) and C3-R deuterium (DV/KR) are 1.021 ± 0.001 and 1.049 ± 0.001, respectively. The glycosylation transition state structures for both Neu5Acα2,3LacβSPh and Neu5Acα2,6LacβSPh were modeled computationally using the experimental KIE values as goodness of fit criteria. Both transition states are late with largely cleaved glycosidic bonds coupled to pyranosyl ring flattening (4H5 half-chair conformation) with little or no nucleophilic involvement of the enzymatic tyrosine residue. Notably, the transition state for the catalyzed hydrolysis of Neu5Acα2,6βSPh appears to incorporate a lesser degree of general-acid catalysis, relative to the 2,3-isomer. DA - 2012/02/29 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7c867330-319e-43c0-859e-77d22ac05b0a ER - TY - JOUR TI - Continuous synthesis and in situ monitoring of biodiesel production in different microfluidic devices DO - 10.1021/ie300486v AU - Martínez Arias, Edgar L. AU - Fazzio Martins, Patricia AU - Jardini Munhoz, André L. AU - Gutierrez-Rivera, Luis AU - Maciel Filho, Rubens T2 - Industrial & Engineering Chemistry Research SN - 0888-5885 SN - 1520-5045 VL - 51 IS - 33 SP - 10755 EP - 10767 AB - Currently, there is great interest in developing new processes for continuous biodiesel synthesis in order to overcome problems imposed by biphasic reaction and thermodynamic equilibrium, as well as to reduce production costs related to the conventional batch reaction processes. The use of microreactors can significantly improve the mixing between reactants and phases, enhancing the transfer rates, and, consequently, increasing biodiesel yields. Therefore, in this work, microreactors with different internal geometries have been fabricated and used for continuous production of biodiesel from castor oil and ethanol. The influences of the microchannel geometry (Tesla-, omega-, and T-shaped) on the performance of the biodiesel synthesis were experimentally studied. Higher biodiesel yields were reached using the Tesla- and omega-shaped microchannels than during the T-shaped microchannels due to better mixture mechanism efficiency. Using a catalyst loading of 1.0 wt % NaOH and a reaction temperature of 50 °C, ethyl ester conversions of 96.7, 95.3, and 93.5% were achieved using Tesla-, omega-, and T-shaped microreactors, respectively. In addition, transesterification reaction in situ monitoring by near-infrared spectroscopy using a fiber-optic probe was evaluated, showing that more studies must be performed in order to allow its use in online monitoring of continuous processes. DA - 2012/08/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d3eeaa7c-dc71-4aaa-8e7e-763d348ec58c ER - TY - JOUR TI - The International Deep Planet Survey I. The frequency of wide-orbit massive planets around A-stars DO - 10.1051/0004-6361/201218991 AU - Vigan, A. AU - Patience, J. AU - Marois, C. AU - Bonavita, M. AU - De Rosa, R. J. AU - Macintosh, B. AU - Song, I. AU - Doyon, R. AU - Zuckerman, B. AU - Lafrenière, D. AU - Barman, T. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 544 SP - A9 AB - Breakthrough direct detections of planetary companions orbiting A-type stars confirm the existence of massive planets at relatively large separations, but dedicated surveys are required to estimate the frequency of similar planetary systems. To measure the first estimation of the giant exoplanetary systems frequency at large orbital separation around A-stars, we have conducted a deep-imaging survey of young (8−400 Myr), nearby (19−84 pc) A- and F-stars to search for substellar companions in the ~10−300 AU range. The sample of 42 stars combines all A-stars observed in previous AO planet search surveys reported in the literature with new AO observations from VLT/NaCo and Gemini/NIRI. It represents an initial subset of the International Deep Planet Survey (IDPS) sample of stars covering M- to B-stars. The data were obtained with diffraction-limited observations in H- and Ks-band combined with angular differential imaging to suppress the speckle noise of the central stars, resulting in typical 5σ detection limits in magnitude difference of 12 mag at 1′′, 14 mag at 2′′ and 16 mag at 5′′ which is sufficient to detect massive planets. A detailed statistical analysis of the survey results is performed using Monte Carlo simulations. Considering the planet detections, we estimate the fraction of A-stars having at least one massive planet (3−14 MJup) in the range 5−320 AU to be inside 5.9−18.8% at 68% confidence, assuming a flat distribution for the mass of the planets. By comparison, the brown dwarf (15−75 MJup) frequency for the sample is 2.0−8.9% at 68% confidence in the range 5−320 AU. Assuming power law distributions for the mass and semimajor axis of the planet population, the AO data are consistent with a declining number of massive planets with increasing orbital radius which is distinct from the rising slope inferred from radial velocity (RV) surveys around evolved A-stars and suggests that the peak of the massive planet population around A-stars may occur atseparations between the ranges probed by existing RV and AO observations. Finally, we report the discovery of three new close M-star companions to HIP 104365 and HIP 42334. DA - 2012/07/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 721e797f-c82f-4364-8783-e582d7100cdd ER - TY - JOUR TI - Solvent free generation of open and skinless foam in poly(l-lactic acid)/Poly(d,l-lactic acid) blends using carbon dioxide DO - 10.1021/ie3000997 AU - Liao, Xia AU - Nawaby, Arghavan V. T2 - Industrial & Engineering Chemistry Research SN - 0888-5885 SN - 1520-5045 VL - 51 IS - 19 SP - 6722 EP - 6730 AB - Foams generated via carbon dioxide (CO2) processing typically exhibit a solid skin layer on the exterior surface and a closed-pore structure with limited interconnectivity in the core section thus limiting its application for biomedical intent. By controlling the properties of poly(l-lactic acid)/poly(d,l-lactic acid) (PLLA/PDLLA) blends and using CO2 with specific processing parameters, skinless foams with interconnected porous structure were prepared in this work using only CO2 as a physical foaming agent, which overcome the necessity to use organic solvents and solid porogens. The crystallization behaviors and sorption kinetics of PLLA and its blends were studied. Addition of PDLLA reduces the crystallinity of PLLA/PDLLA blends while treated with CO2 as compared to neat PLLA. The solubility and diffusion coefficients of CO2 in PLLA and its blends were found to be similar. Furthermore, the effect of PLLA/PDLLA blend ratio and CO2 treatment conditions on the foam morphologies was investigated. Through fine parameter control, well interconnected pore structures with a porous surface were generated. Results indicated that by controlling the physical properties of samples combined with optimizing CO2 foaming process, it is indeed possible to create biodegradable interconnected porous structures for potential biomedical applications. DA - 2012/05/16 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3857ec58-b041-4cc4-8dd7-014af8fd6b8c ER - TY - JOUR TI - HD 96446: a puzzle for current models of magnetospheres? DO - 10.1051/0004-6361/201218988 AU - Neiner, C. AU - Landstreet, J. D. AU - Alecian, E. AU - Owocki, S. AU - Kochukhov, O. AU - Bohlender, D. AU - MiMes Collaboration T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 546 AB - Context. Oblique magnetic dipole fields have been detected in Bp stars for several decades, and more recently also in normal massive stars. In the past decade, it has been established that stellar magnetospheres form through the channelling and confinement of an outflowing stellar wind by the stellar magnetic field. This explains specific properties of magnetic massive stars, such as their rotationally modulated photometric light curve, Hα emission, UV spectra, and X-ray emission. Aims. In the framework of the MiMeS (Magnetism in Massive Stars) project, four HARPSpol observations of the magnetic Bp star HD 96446 have been obtained. HD 96446 is very similar to σ Ori E, the prototype of centrifugally supported rigidly rotating magnetospheres (CM) and is therefore a perfect target to study the validity of this model. Methods. We first updated the basic parameters of HD 96446 and studied its spectral variability. We then analysed the HARPSpol spectropolarimetric observations using the LSD (Least-Squares Deconvolution) technique to derive the longitudinal magnetic field and Zeeman signatures in various types of lines. With LTE spectrum modelling, we derived constraints on the field modulus, the rotational velocity, and the inclination angle, and measured non-solar abundances of several elements which we checked with NLTE modelling. Finally, we calculated the magnetic confinement and Alfvén and Kepler radii from the stellar magnetic field and rotation properties, and we examined the various types of magnetospheres that may be present around HD 96446. Results. We find radial velocity variations with a period around 2.23 h, that we attribute to β Cep-type p-mode pulsations. We detect clear direct magnetic Stokes V signatures with slightly varying values of the longitudinal magnetic field, typical of an oblique dipole rotator, and show that these signatures are not much perturbed by the radial velocity variations. The magnetic confinement parameter and Alfvén radius in the centrifugally supported, rigidly-rotating magnetosphere (CM) model points towards the presence of confined material in the magnetosphere. However, HD 96446 does not present signatures of the presence of such confined material, such as Hα emission. Conclusions. We conclude that, even though HD 96446 fulfills all criteria to host a CM with confined material, it does not. The rotation period must be significantly revised, or another model of magnetosphere with a leakage mechanism will need to be developed to explain the magnetic environment of this star. DA - 2012/10/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8502fdbb-4eeb-4a4e-9b9f-c48c2fc53c6e ER - TY - JOUR TI - Atmospheric characterization of cold exoplanets using a 1.5-m coronagraphic space telescope DO - 10.1051/0004-6361/201218954 AU - Maire, A.-L. AU - Galicher, R. AU - Boccaletti, A. AU - Baudoz, P. AU - Schneider, J. AU - Cahoy, K. L. AU - Stam, D. M. AU - Traub, W. A. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 541 SP - A83 AB - Context. High-contrast imaging is currently the only available technique for the study of the thermodynamical and compositional properties of exoplanets in long-period orbits, comparable to the range from Venus to Jupiter. The SPICES (Spectro-Polarimetric Imaging and Characterization of Exoplanetary Systems) project is a coronagraphic space telescope dedicated to the spectro-polarimetric analysis of gaseous and icy giant planets as well as super-Earths at visible wavelengths. So far, studies for high-contrast imaging instruments have mainly focused on technical feasibility because of the challenging planet/star flux ratio of 10-8−10-10 required at short separations (200 mas or so) to image cold exoplanets. However, the main interest of such instruments, namely the analysis of planet atmospheric/surface properties, has remained largely unexplored. Aims. The aim of this paper is to determine which planetary properties SPICES or an equivalent direct imaging mission can measure, considering realistic reflected planet spectra and instrument limitation. Methods. We use numerical simulations of the SPICES instrument concept and theoretical planet spectra to carry out this performance study. We also define a criterion on the signal-to-noise ratio of the measured spectrum to determine under which conditions SPICES can retrieve planetary physical properties. Results. We find that the characterization of the main planetary properties (identification of molecules, effect of metallicity, presence of clouds and type of surfaces) would require a median signal-to-noise ratio of at least 30. In the case of a solar-type star ≤10 pc, SPICES will be able to study Jupiters and Neptunes up to ~5 and ~2 AU respectively, because of the drastic flux decrease with separation. It would also analyze cloud and surface coverage of super-Earths of radius 2.5 Earth radii at 1 AU. Finally, we determine the potential targets in terms of planet separation, radius and distance for several stellar types. For a Sun analog, we show that SPICES could characterize Jupiters (M ≥ 30 Earth masses) as small as 0.5 Jupiter radii at ≲2 AU up to 10 pc, and super-Earths at 1−2 AU for the handful of stars that exist within 4−5 pc. Potentially, SPICES could perform analysis of a hypothetical Earth-size planet around α Cen A and B. However, these results depend on the planetary spectra we use, which are derived for a few planet parameters assuming a solar-type host star. Grids of model spectra are needed for a further performance analysis. Our results obtained for SPICES are also applicable to other small (1−2 m) coronagraphic space telescopes. DA - 2012/05/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b9a42d70-3c85-4978-905d-3073a405f665 ER - TY - JOUR TI - Stripped gas as fuel for newly formed H ii regions in the encounter between VCC 1249 and M 49: a unified picture from NGVS and GUViCS DO - 10.1051/0004-6361/201218895 AU - Arrigoni Battaia, F. AU - Gavazzi, G. AU - Fumagalli, M. AU - Boselli, A. AU - Boissier, S. AU - Cortese, L. AU - Heinis, S. AU - Ferrarese, L. AU - Côté, P. AU - Mihos, J. C. AU - Cuillandre, J. C. AU - Duc, P.-A. AU - Durrell, P. AU - Gwyn, S. AU - Jordán, A. AU - Liu, C. AU - Peng, E. AU - Mei, S. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 543 AB - Context. We study the peculiar interacting galaxy system of VCC 1249/M 49 located in the core of the Virgo B subcluster. Owing to a recent interaction between the dwarf galaxy VCC 1249 and the halo gas of the elliptical galaxy M 49, neutral hydrogen has been displaced from the interstellar medium of this dwarf into the Virgo intracluster medium. Observations also reveal multiple compact star-forming regions (aka H ii regions) that are embedded in this H i cloud, with a projected separation up to 13 kpc from VCC 1249 in the northwest direction. Aims. Motivated by recent near-ultraviolet imaging from the GALEX Ultraviolet Virgo Cluster Survey (GUViCS) of the VCC 1249/M 49 system that shows significant ongoing/recent star formation in the compact regions, we aim to constrain the origin of these outlying H ii regions with a multi-wavelength approach. Methods. Using deep optical (u,g,i,z) imaging from the Next Generation Virgo Cluster Survey (NGVS) and new Hα imaging obtained at the San Pedro Martir observatory together with Keck long-slit spectroscopy, we characterize the star formation rates, ages, and metallicity of VCC 1249 and its outlying compact regions. Moreover, we analyze the color and luminosity profile of the galaxy to investigate its recent interaction with M 49. Results. Our new observations indicate that VCC 1249 underwent a recent interaction with M 49 in which both ram-pressure stripping and tidal interaction occured. The joint action of the two mechanisms led to the removal of the H i gas from the interstellar medium of VCC 1249, while the gravitational tides triggered the stellar tail and counter-tail of VCC 1249. Our stellar population synthesis analysis reveals that the star formation in this galaxy was truncated around 200 Myr ago and that the outlying H ii regions were born in situ ≈10 Myr ago out of pre-enriched gas removed from the dwarf galaxy. These observations also reveal that interactions between central and satellite galaxies similar to those between VCC 1249/M 49 may be an effective way of dispersing metals into the halos of massive galaxies. DA - 2012/06/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cc2fe2ca-9412-4616-b6dc-92612352ede1 ER - TY - JOUR TI - A background galaxy in the field of the β Pictoris debris disk DO - 10.1051/0004-6361/201118631 AU - Regibo, S. AU - Vandenbussche, B. AU - Waelkens, C. AU - Acke, B. AU - Sibthorpe, B. AU - Nottebaere, M. AU - Voet, K. AU - Di Francesco, J. AU - Fridlund, M. AU - Gear, W. K. AU - Ivison, R. J. AU - Olofsson, G. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 541 AB - Herschel images in six photometric bands show the thermal emission of the debris disk surrounding β Pic. In the three PACS bands at 70 μm, 100 μm and 160 μm and in the 250 μm SPIRE band, the disk is well-resolved, and additional photometry is available in the SPIRE bands at 350 μm and 500 μm, where the disk is only marginally resolved. The SPIRE maps reveal a blob to the southwest of β Pic, coinciding with submillimetre detection of excess emission in the disk. We investigated the nature of this blob. Our comparison of the colours, spectral energy distribution and size of the blob, the disk and the background sources shows that the blob is most likely a background source with a redshift between z = 1.0 and z = 1.6. DA - 2012/04/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 15bc7ea2-d010-4743-95aa-6d0562396fc4 ER - TY - JOUR TI - The JCMT 12CO(3–2) survey of the Cygnus X region I. A pathfinder DO - 10.1051/0004-6361/201118600 AU - Gottschalk, M. AU - Kothes, R. AU - Matthews, H. E. AU - Landecker, T. L. AU - Dent, W. R. F. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 541 SP - A79 AB - Context. Cygnus X is one of the most complex areas in the sky, rich in massive stars; Cyg OB2 (2600 stars, 120 O stars) and other OB associations lie within its boundaries. This complicates interpretation, but also creates the opportunity to investigate accretion into molecular clouds and many subsequent stages of star formation, all within one small field of view. Understanding large complexes like Cygnus X is the key to understanding the dominant role that massive star complexes play in galaxies across the Universe. Aims. The main goal of this study is to establish feasibility of a high-resolution CO survey of the entire Cygnus X region by observing part of it as a pathfinder, and to evaluate the survey as a tool for investigating the star-formation process. We can investigate the mass accretion history of outflows, study interaction between star-forming regions and their cold environment, and examine triggered star formation around massive stars. Methods. A 2° × 4° area of the Cygnus X region has been mapped in the 12CO(3–2) line at an angular resolution of 15′′ and a velocity resolution of ~0.4 km s-¹ using HARP-B and ACSIS on the James Clerk Maxwell Telescope. The star formation process is heavily connected to the life-cycle of the molecular material in the interstellar medium. The high critical density of the 12CO(3–2) transition reveals clouds in key stages of molecule formation, and shows processes that turn a molecular cloud into a star. Results. We observed ~15% of Cygnus X, and demonstrated that a full survey would be feasible and rewarding. We detected three distinct layers of 12CO(3–2) emission, related to the Cygnus Rift (500–800 pc), to W75N (1–1.8 kpc), and to DR 21 (1.5–2.5 kpc). Within the Cygnus Rift, H i self-absorption features are tightly correlated with faint diffuse CO emission, while HISA features in the DR 21 layer are mostly unrelated to any CO emission. 47 molecular outflows were detected in the pathfinder, 27 of them previously unknown. Sequentially triggered star formation is a widespread phenomenon. DA - 2012/05/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 098093d5-c076-4d9c-8898-c4c88183985d ER - TY - JOUR TI - Herschel images of Fomalhaut DO - 10.1051/0004-6361/201118581 AU - Acke, B. AU - Min, M. AU - Dominik, C. AU - Vandenbussche, B. AU - Sibthorpe, B. AU - Waelkens, C. AU - Olofsson, G. AU - Degroote, P. AU - Smolders, K. AU - Pantin, E. AU - Barlow, M. J. AU - Blommaert, J. A. D. L. AU - Brandeker, A. AU - De Meester, W. AU - Dent, W. R. F. AU - Exter, K. AU - Di Francesco, J. AU - Fridlund, M. AU - Gear, W. K. AU - Glauser, A. M. AU - Greaves, J. S. AU - Harvey, P. M. AU - Henning, Th. AU - Hogerheijde, M. R. AU - Holland, W. S. AU - Huygen, R. AU - Ivison, R. J. AU - Jean, C. AU - Liseau, R. AU - Naylor, D. A. AU - Pilbratt, G. L. AU - Polehampton, E. T. AU - Regibo, S. AU - Royer, P. AU - Sicilia-Aguilar, A. AU - Swinyard, B. M. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 540 SP - A125 AB - Context. Fomalhaut is a young (2 ± 1 × 10^8 years), nearby (7.7 pc), 2 M⊙ star that is suspected to harbor an infant planetary system, interspersed with one or more belts of dusty debris. Aims. We present far-infrared images obtained with the Herschel Space Observatory with an angular resolution between 5.7′′ and 36.7′′ at wavelengths between 70 μm and 500 μm. The images show the main debris belt in great detail. Even at high spatial resolution, the belt appears smooth. The region in between the belt and the central star is not devoid of material; thermal emission is observed here as well. Also at the location of the star, excess emission is detected. We aim to construct a consistent image of the Fomalhaut system. Methods. We use a dynamical model together with radiative-transfer tools to derive the parameters of the debris disk. We include detailed models of the interaction of the dust grains with radiation, for both the radiation pressure and the temperature determination. Comparing these models to the spatially resolved temperature information contained in the images allows us to place strong constraints on the presence of grains that will be blown out of the system by radiation pressure. We use this to derive the dynamical parameters of the system. Results. The appearance of the belt points toward a remarkably active system in which dust grains are produced at a very high rate by a collisional cascade in a narrow region filled with dynamically excited planetesimals. Dust particles with sizes below the blow-out size are abundantly present. The equivalent of 2000 one-km-sized comets are destroyed every day, out of a cometary reservoir amounting to 110 Earth masses. From comparison of their scattering and thermal properties, we find evidence that the dust grains are fluffy aggregates, which indicates a cometary origin. The excess emission at the location of the star may be produced by hot dust with a range of temperatures, but may also be due to gaseous free-free emission from a stellar wind. DA - 2012/04/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0e655a0e-03f6-45f5-aba3-4e2b9d6b084a ER - TY - JOUR TI - Cluster-formation in the Rosette molecular cloud at the junctions of filaments DO - 10.1051/0004-6361/201118566 AU - Schneider, N. AU - Csengeri, T. AU - Hennemann, M. AU - Motte, F. AU - Didelon, P. AU - Federrath, C. AU - Bontemps, S. AU - Di Francesco, J. AU - Arzoumanian, D. AU - Minier, V. AU - André, Ph. AU - Hill, T. AU - Zavagno, A. AU - Nguyen-Luong, Q. AU - Attard, M. AU - Bernard, J.-Ph. AU - Elia, D. AU - Fallscheer, C. AU - Griffin, M. AU - Kirk, J. AU - Klessen, R. AU - Könyves, V. AU - Martin, P. AU - Men’shchikov, A. AU - Palmeirim, P. AU - Peretto, N. AU - Pestalozzi, M. AU - Russeil, D. AU - Sadavoy, S. AU - Sousbie, T. AU - Testi, L. AU - Tremblin, P. AU - Ward-Thompson, D. AU - White, G. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 540 SP - L11 AB - Aims. For many years feedback processes generated by OB-stars in molecular clouds, including expanding ionization fronts, stellar winds, or UV-radiation, have been proposed to trigger subsequent star formation. However, hydrodynamic models including radiation and gravity show that UV-illumination has little or no impact on the global dynamical evolution of the cloud. Instead, gravitational collapse of filaments and/or merging of filamentary structures can lead to building up dense high-mass star-forming clumps. However, the overall density structure of the cloud has a large influence on this process, and requires a better understanding. Methods. The Rosette molecular cloud, irradiated by the NGC 2244 cluster, is a template region for triggered star-formation, and we investigated its spatial and density structure by applying a curvelet analysis, a filament-tracing algorithm (DisPerSE), and probability density functions (PDFs) on Herschel column density maps, obtained within the HOBYS key program. Results. The analysis reveals not only the filamentary structure of the cloud but also that all known infrared clusters except one lie at junctions of filaments, as predicted by turbulence simulations. The PDFs of sub-regions in the cloud show systematic differences. The two UV-exposed regions have a double-peaked PDF we interprete as caused by shock compression, while the PDFs of the center and other cloud parts are more complex, partly with a power-law tail. A deviation of the log-normal PDF form occurs at AV ≈ 9m for the center, and around 4m for the other regions. Only the part of the cloud farthest from the Rosette nebula shows a log-normal PDF. Conclusions. The deviations of the PDF from the log-normal shape typically associated with low- and high-mass star-forming regions at AV ≈ 3–4^m and 8–10^m, respectively, are found here within the very same cloud. This shows that there is no fundamental difference in the density structure of low- and high-mass star-forming regions. We conclude that star-formation in Rosette – and probably in high-mass star-forming clouds in general – is not globally triggered by the impact of UV-radiation. Moreover, star formation takes place in filaments that arose from the primordial turbulent structure built up during the formation of the cloud. Clusters form at filament mergers, but star formation can be locally induced in the direct interaction zone between an expanding H II-region and the molecular cloud. DA - 2012/04/04 PY - 2012 LA - eng N1 - Erratum published in volume 551, article C1, March 2013. DOI: 10.1051/0004-6361/201118566e C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ca449baf-d51a-405b-9874-d28490a6fa92 ER - TY - JOUR TI - The WIRCam Deep Survey DO - 10.1051/0004-6361/201118547 AU - Bielby, R. AU - Hudelot, P. AU - McCracken, H. J. AU - Ilbert, O. AU - Daddi, E. AU - Le Fèvre, O. AU - Gonzalez-Perez, V. AU - Kneib, J.-P. AU - Marmo, C. AU - Mellier, Y. AU - Salvato, M. AU - Sanders, D. B. AU - Willott, C. J. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 545 SP - A23 AB - We present a new near-infrared imaging survey in the four CFHTLS deep fields: the WIRCam Deep Survey or “WIRDS”. WIRDS comprises extremely deep, high quality (FWHM ~ 0.6″) J, H, and Ks imaging covering a total effective area of 2.1 deg2 and reaching AB 50% completeness limits of ≈ 24.5. We combine our images with the CFHTLS to create a unique eight-band ugrizJHKS photometric catalogues in the four CFHTLS deep fields; these four separate fields allow us to make a robust estimate of the effect of cosmic variance for all our measurements. We use these catalogues in combination with ≈ 9800 spectroscopic redshifts to estimate precise photometric redshifts (σΔz/(1 + z) ≲ 0.03 at i < 25), galaxy types, star-formation rates and stellar masses for a unique sample of ≈ 1.8 million galaxies. Our JHKs number counts are consistent with previous studies. We apply the “BzK” selection to our gzK filter set and find that the star forming BzK selection successfully selects 76% of star-forming galaxies in the redshift range 1.4 < z < 2.5 in our photometric catalogue, based on our photometric redshift measurement. Similarly the passive BzK selection returns 52% of the passive 1.4 < z < 2.5 population identified in the photometric catalogue. We present the mass functions of the total galaxy population as a function of redshift up to z = 2 and present fits using double Schechter functions. A mass-dependent evolution of the mass function is seen with the numbers of galaxies with masses of M ≲ 1010.75 still evolving at z ≲ 1, but galaxies of higher mass reaching their present day numbers by z ~ 0.8−1. This is consistent with the present picture of downsizing in galaxy evolution. We compare our results with the predictions of the GALFORM semi-analytical galaxy formation model and find that the simulations provide a relatively successful fit to the observed mass functions at intermediate masses (i.e. 10 ≲ log    (M/M⊙) ≲ 11). However, as is common with semi-analytical predictions of the mass function, the GALFORM results under-predict the mass function at low masses (i.e. log    (M/M⊙) ≲ 10), whilst the fit as a whole degrades beyondredshifts of z ~ 1.2. All photometric catalogues and images are made publicly available from TERAPIX and CADC. DA - 2012/08/31 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d7ca1882-f22f-481e-b6b8-656e0317408c ER - TY - JOUR TI - An improved map of the Galactic Faraday sky DO - 10.1051/0004-6361/201118526 AU - Oppermann, N. AU - Junklewitz, H. AU - Robbers, G. AU - Bell, M. R. AU - Enßlin, T. A. AU - Bonafede, A. AU - Braun, R. AU - Brown, J. C. AU - Clarke, T. E. AU - Feain, I. J. AU - Gaensler, B. M. AU - Hammond, A. AU - Harvey-Smith, L. AU - Heald, G. AU - Johnston-Hollitt, M. AU - Klein, U. AU - Kronberg, P. P. AU - Mao, S. A. AU - Mcclure-Griffiths, N. M. AU - O’Sullivan, S. P. AU - Pratley, L. AU - Robishaw, T. AU - Roy, S. AU - Schnitzeler, D. H. F. M. AU - Sotomayor-Beltran, C. AU - Stevens, J. AU - Stil, J. M. AU - Sunstrum, C. AU - Tanna, A. AU - Taylor, A. R. AU - Van Eck, C. L. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 542 SP - A93 AB - We aim to summarize the current state of knowledge regarding Galactic Faraday rotation in an all-sky map of the Galactic Faraday depth. For this we have assembled the most extensive catalog of Faraday rotation data of compact extragalactic polarized radio sources to date. In the map-making procedure we used a recently developed algorithm that reconstructs the map and the power spectrum of a statistically isotropic and homogeneous field while taking into account uncertainties in the noise statistics. This procedure is able to identify some rotation angles that are offset by an integer multiple of π. The resulting map can be seen as an improved version of earlier such maps and is made publicly available, along with a map of its uncertainty. For the angular power spectrum we find a power law behavior Cℓ ∝ ℓ^-2.17 for a Faraday sky where an overall variance profile as a function of Galactic latitude has been removed, in agreement with earlier work. We show that this is in accordance with a 3D Fourier power spectrum P(k) ∝ k^-2.17 of the underlying field neBr under simplifying geometrical and statistical assumptions. DA - 2012/06/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7548a48b-7711-4c91-9a43-7dab484f9375 ER - TY - JOUR TI - The abundance of C¹⁸8O and HDO in the envelope and hot core of the intermediate mass protostar NGC 7129 FIRS 2 DO - 10.1051/0004-6361/201118478 AU - Fuente, A. AU - Caselli, P. AU - Mccoey, C. AU - Cernicharo, J. AU - Johnstone, D. AU - Fich, M. AU - Van Kempen, T. AU - Van Dishoeck, E. AU - Yıldız, U. AU - Visser, R. AU - Kristensen, L. AU - Alonso-Albi, T. AU - Herpin, F. AU - Tisi, S. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 540 SP - A75 AB - Context. NGC 7129 FIRS 2 is a young intermediate-mass (IM) protostar, which is associated with two energetic bipolar outflows and displays clear signs of the presence of a hot core. It has been extensively observed with ground based telescopes and within the WISH guaranteed time Herschel key program. Aims. This paper is dedicated to the modeling of the C18O and HDO lines in NGC 7129 FIRS 2. Our goal is to investigate the chemistry in the envelope and hot core of this IM protostar. Conclusions.Herschel data combined with ground based observations have allowed us to estimate the C18O and HDO abundance in the protostellar envelope and hot core of an IM protostar. The HDO abundance in the hot core is ~0.4−1 × 10^-7, similar to that found in the hot corinos NGC 1333 IRAS 2A and IRAS 16293−2422. The C18O abundance, at ≈ 1.6 × 10^-8, is a factor of 10 lower than the reference value. DA - 2012/03/28 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e91c2e84-9b21-4f8a-b742-35053fdbe7d7 ER - TY - JOUR TI - The double sub-giant branch of NGC 6656 (M 22): a chemical characterization DO - 10.1051/0004-6361/201118381 AU - Marino, A. F. AU - Milone, A. P. AU - Sneden, C. AU - Bergemann, M. AU - Kraft, R. P. AU - Wallerstein, G. AU - Cassisi, S. AU - Aparicio, A. AU - Asplund, M. AU - Bedin, R. L. AU - Hilker, M. AU - Lind, K. AU - Momany, Y. AU - Piotto, G. AU - Roederer, I. U. AU - Stetson, P. B. AU - Zoccali, M. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 541 SP - A15 AB - We present an abundance analysis of 101 subgiant branch (SGB) stars in the globular cluster M 22. Using low-resolution FLAMES/GIRAFFE spectra we have determined abundances of the neutron-capture strontium and barium and the light element carbon. With these data we explore relationships between the observed SGB photometric split in this cluster and two stellar groups characterized by different contents of iron, slow neutron-capture process (s-process) elements, and the α element calcium, which we previously discovered in M 22’s red-giant stars. We show that the SGB stars correlate in chemical composition and the color–magnitude diagram position. The stars with higher metallicity and relative s-process abundances define a fainter SGB, while stars with lower metallicity and s-process content reside on a relatively brighter SGB. This result has implications for the relative ages of the two stellar groups of M 22. In particular, it is inconsistent with a broad spread in ages of the two SGBs. By accounting for the chemical content of the two stellar groups, isochrone fitting of the double SGB suggests that their agesare not different by more than ~300 Myr. DA - 2012/04/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 566d8bb5-a5c3-4288-85a1-c7b68b0a1853 ER - TY - JOUR TI - A tidal disruption-like X-ray flare from the quiescent galaxy SDSS J120136.02+300305.5 DO - 10.1051/0004-6361/201118367 AU - Saxton, R. D. AU - Read, A. M. AU - Esquej, P. AU - Komossa, S. AU - Dougherty, S. AU - Rodriguez-Pascual, P. AU - Barrado, D. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 541 AB - Aims. The study of tidal disruption flares from galactic nuclei has historically been hampered by a lack of high quality spectral observations taken around the peak of the outburst. Here we introduce the first results from a program designed to identify tidal disruption events at their peak by making near-real-time comparisons of the flux seen in XMM-Newton slew sources with that seen in ROSAT. Methods. Flaring extragalactic sources, which do not appear to be AGN, are monitored with Swift and XMM-Newton to track their temporal and spectral evolution. Timely optical observations are made to monitor the reaction of circumnuclear material to the X-ray flare. Results. SDSS J120136.02+300305.5 was detected in an XMM-Newton slew from June 2010 with a flux 56 times higher than an upper limit from ROSAT, corresponding to LX ~ 3 × 1044 erg s-¹. It has the optical spectrum of a quiescent galaxy (z = 0.146). Overall the X-ray flux has evolved consistently with the canonical t^−5/3 model, expected for returning stellar debris, fading by a factor ~300 over 300 days. In detail the source is very variable and became invisible to Swift between 27 and 48 days after discovery, perhaps due to self-absorption. The X-ray spectrum is soft but is not the expected tail of optically thick thermal emission. It may be fit with a Bremsstrahlung or double-power-law model and is seen to soften with time and declining flux. Optical spectra taken 12 days and 11 months after discovery indicate a deficit of material in the broad line and coronal line regions of this galaxy, while a deep radio non-detection implies that a jet was not launched during this event. DA - 2012/05/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e3147155-b439-4b86-8351-f18dea7718ec ER - TY - JOUR TI - Herschel observations of a potential core-forming clump: Perseus B1-E DO - 10.1051/0004-6361/201117934 AU - Sadavoy, S. I. AU - Di Francesco, J. AU - André, Ph. AU - Pezzuto, S. AU - Bernard, J.-P. AU - Bontemps, S. AU - Bressert, E. AU - Chitsazzadeh, S. AU - Fallscheer, C. AU - Hennemann, M. AU - Hill, T. AU - Martin, P. AU - Motte, F. AU - Nguyn Lu’o’ng, Q. AU - Peretto, N. AU - Reid, M. AU - Schneider, N. AU - Testi, L. AU - White, G. J. AU - Wilson, C. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 540 SP - A10 KW - stars; formation; dust; extinction; Perseus B1-E AB - We present continuum observations of the Perseus B1-E region from the Herschel Gould Belt Survey. These Herschel data reveal a loose grouping of substructures at 160−500 μm not seen in previous submillimetre observations. We measure temperature and column density from these data and select the nine densest and coolest substructures for follow-up spectral line observations with the Green Bank Telescope. We find that the B1-E clump has a mass of ~100 M⊙ and appears to be gravitationally bound. Furthermore, of the nine substructures examined here, one substructure (B1-E2) appears to be itself bound. The substructures are typically less than a Jeans length from their nearest neighbour and thus, may interact on a timescale of ~1 Myr. We propose that B1-E may be forming a first generation of dense cores, which could provide important constraints on the initial conditions of prestellar core formation. Our results suggest that B1-E may be influenced by a strong, localized magnetic field, but further observations are still required. DA - 2012/03/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d769ef23-911d-4982-b33d-10d196ce74b2 ER - TY - JOUR TI - A Vacancy-Disordered, Oxygen-Deficient Perovskite with Long-Range Magnetic Ordering: Local and Average Structures and Magnetic Properties of Sr 2 Fe 1.5 Cr 0.5 O 5 DO - 10.1021/ic202590r AU - Ramezanipour, Farshid AU - Greedan, John E. AU - Siewenie, Joan AU - Donaberger, Ronald L. AU - Turner, Stuart AU - Botton, Gianluigi A. T2 - Inorganic Chemistry SN - 0020-1669 SN - 1520-510X VL - 51 IS - 4 SP - 2638 EP - 2644 AB - The local and average crystal structures and magnetic properties of the oxygen-deficient perovskite Sr2Fe1.5Cr0.5O5+y were studied using powder X-ray and neutron diffraction, neutron-pair distribution function analysis, and electron energy-loss spectroscopy. This material crystallizes in the cubic Pm3̅m space group, with a = 3.94491(14) Å. The oxygen vacancies are distributed randomly throughout the perovskite-type structure, and the average coordination number of the Fe(Cr) sites is 5. Refinement of the neutron diffraction data indicates y 0.05. This is in discordance with an earlier report on a material with the same nominal composition and cell constant. Electron energy-loss Cr L2,3-edge spectroscopy shows that Cr³⁺ is present, which is also contrary to previous speculation. Neutron-pair distribution function studies show that a brownmillerite-like model involving ordered vacancies and alternating octahedral and tetrahedral coordination at the metal sites, gives a better description of the local structure out to 5 Å. A remarkable phenomenon determined by neutron diffraction in Sr2Fe1.5Cr0.5O5 is the occurrence of a long-range G-type antiferromagnetic ordering with Tc ≈ 565 K because cubic oxygen-deficient perovskites with B-site disorder usually do not undergo transitions to magnetically ordered states. The observation of long-range antiferromagnetic order and the Tc value are in accordance with previous Mössbauer spectroscopic studies. DA - 2012/02/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d5e8bbea-f825-4a56-b732-783dfd9ee2be ER - TY - JOUR TI - Tip-tilt estimation and correction using FQPM coronagraphic images DO - 10.1051/0004-6361/201117898 AU - Mas, M. AU - Baudoz, P. AU - Rousset, G. AU - Galicher, R. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 539 KW - adaptive optics; high angular resolution; image processing AB - Context. Direct imaging of exoplanets located a few AU from their hosting star requires angular resolution at the diffraction limit of large telescopes and a contrast level in the image of 10^5 to 10^10. Simultaneous use of adaptive optics and coronagraphy is mandatory to fulfil these requirements. Aims. Coronagraphs are usually very sensitive to pointing errors upstream of their focal plane mask. Approaches to measuring these errors in conventional adaptive optics systems consist in setting a wavefront sensor in an additional channel. Differential aberrations between the coronagraphic channel and the additional one induce a loss in performance. To tackle this limitation, we propose a new technique for measuring the tip-tilt errors directly from the coronagraphic image. Methods. Our method uses the relations between the intensity distribution in the coronagraphic image and upstream tip-tilt errors. We also propose a method of estimating the tip-tilt errors downstream of the focal plane mask. We validate at visible wavelength our upstream and downstream tip-tilt estimation and compensation techniques with numerical simulation images and on laboratory images. Results. Numerical simulations predict that our techniques correct for the tip-tilt errors to a 1.3 × 10-² λ/D level when considering a λ/40 wavefront error upstream of the coronagraph. In laboratory, where the coronagraph is mostly limited by wavefront errors, we correct for the tip-tilt errors with an accuracy better than 6.5 × 10-² λ/D. Conclusions. We demonstrate in numerical simulations and in laboratory that our technique can efficiently estimate the tip-tilt errors directly from the coronagraphic image with no additional channel. It is robust and can be used with small wavefront errors. It should be applicable to planet imager systems currently in preparation, such as SPHERE and MIRI/JWST. DA - 2012/03/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5f6747a1-6987-44bb-838d-016b22a51408 ER - TY - JOUR TI - Nuclear resonance vibrational spectra of five-coordinate imidazole-ligated iron(II) porphyrinates DO - 10.1021/ic201580v AU - Hu, Chuanjiang AU - Barabanschikov, Alexander AU - Ellison, Mary K. AU - Zhao, Jiyong AU - Alp, E. Ercan AU - Sturhahn, Wolfgang AU - Zgierski, Marek Z. AU - Sage, J. Timothy AU - Scheidt, W. Robert T2 - Inorganic Chemistry SN - 0020-1669 SN - 1520-510X VL - 51 IS - 3 SP - 1359 EP - 1370 AB - Nuclear resonance vibrational spectra have been obtained for six five-coordinate imidazole-ligated iron(II) porphyrinates, [Fe(Por)(L)] (Por = tetraphenylporphyrinate, octaethylporphyrinate, tetratolylporphyrinate, or protoporphyrinate IX and L = 2-methylimidazole or 1,2-dimethylimidazole). Measurements have been made on both powder and oriented crystal samples. The spectra are dominated by strong signals around 200–300 cm–1. Although the in-plane and out-of-plane vibrations are seriously overlapped, oriented crystal spectra allow their deconvolution. Thus, oriented crystal experimental data, along with density functional theory (DFT) calculations, enable the assignment of key vibrations in the spectra. Molecular dynamics are also discussed. The nature of the Fe–NIm vibrations has been elaborated further than was possible from resonance Raman studies. Our study suggests that the Fe motions are coupled with the porphyrin core and peripheral groups motions. Both peripheral groups and their conformations have significant influence on the vibrational spectra (position and shape). DA - 2012/02/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ce12c5cd-3678-4db7-844e-85df7167ce7f ER - TY - JOUR TI - Topotactic oxidation pathway of ScTiO3 and high-temperature structure evolution of ScTiO3.5 and Sc4Ti3O12-type phases DO - 10.1021/ic201034x AU - Shafi, Shahid P. AU - Hernden, Bradley C. AU - Cranswick, Lachlan M. D. AU - Hansen, Thomas C. AU - Bieringer, Mario T2 - Inorganic Chemistry SN - 0020-1669 SN - 1520-510X VL - 51 IS - 3 SP - 1269 EP - 1277 AB - The novel oxide defect fluorite phase ScTiO3.5 is formed during the topotactic oxidation of ScTiO3 bixbyite. We report the oxidation pathway of ScTiO3 and structure evolution of ScTiO3.5, Sc4Ti3O12, and related scandium-deficient phases as well as high-temperature phase transitions between room temperature and 1300 °Cusing in-situ X-ray diffraction. We provide the first detailed powder neutron diffraction study for ScTiO3. ScTiO3 crystallizes in the cubic bixbyite structure in space group Ia3̅ (206) with a = 9.7099(4) Å. The topotactic oxidation product ScTiO3.5 crystallizes in an oxide defect fluorite structure in space group Fm3̅m (225) with a = 4.89199(5) Å. Thermogravimetric and differential thermal analysis experiments combined with in-situ X-ray powder diffraction studies illustrate a complex sequence of a topotactic oxidation pathway, phase segregation, and ion ordering at high temperatures. The optimized bulk synthesis for phase pure ScTiO3.5 is presented. In contrast to the vanadium-based defect fluorite phases AVO3.5+x (A = Sc, In) the novel titanium analogue ScTiO3.5 is stable over a wide temperature range. Above 950 °C ScTiO3.5 undergoes decomposition with the final products being Sc4Ti3O12 and TiO2. Simultaneous Rietveld refinements against powder X-ray and neutron diffraction data showed that Sc4Ti3O12 also exists in the defect fluorite structure in space group Fm3̅m (225) with a = 4.90077(4) Å. Sc4Ti3O12 undergoes partial reduction in CO/Ar atmosphere to form Sc4Ti3O11.69(2). DA - 2012/02/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 780e8d2b-f39e-4280-bb46-1e845bd695e5 ER - TY - JOUR TI - The Herschel view of the on-going star formation in the Vela-C molecular cloud DO - 10.1051/0004-6361/201117811 AU - Giannini, T. AU - Elia, D. AU - Lorenzetti, D. AU - Molinari, S. AU - Motte, F. AU - Schisano, E. AU - Pezzuto, S. AU - Pestalozzi, M. AU - Di Giorgio, A. M. AU - André, P. AU - Hill, T. AU - Benedettini, M. AU - Bontemps, S. AU - Di Francesco, J. AU - Fallscheer, C. AU - Hennemann, M. AU - Kirk, J. AU - Minier, V. AU - Lu’o’ng, Q. Nguyn AU - Polychroni, D. AU - Rygl, K. L. J. AU - Saraceno, P. AU - Schneider, N. AU - Spinoglio, L. AU - Testi, L. AU - Ward-Thompson, D. AU - White, G. J. T2 - Astronomy & Astrophysics SN - 0004-6361 SN - 1432-0746 VL - 539 SP - A156 KW - individual objects; Vela-C; clouds; stars; formation; submillimeter; circumstellar matter AB - Aims. As part of the Herschel guaranteed time key programme “HOBYS”, we present the PACS and SPIRE photometric survey of the star-forming region Vela-C, one of the nearest sites of low-to-high-mass star formation in the Galactic plane. Our main objectives are to take a census of the cold sources and to derive their mass distribution down to a few solar masses. Methods. Vela-C was observed with PACS and SPIRE in parallel mode at five wavelengths between 70μm and 500μm over an area of about 3 square degrees. A photometric catalogue was extracted from the detections in each of the five bands, using a threshold of 5σ over the local background. Out of this catalogue we selected a robust sub-sample of 268 sources, of which ∼75% are cloud clumps (diameter between 0.05 pc and 0.13 pc) and 25% are cores (diameter between 0.025 pc and 0.05 pc). Their spectral energy distributions (SEDs) were fitted with a modified black body function. We classify 48 sources as protostellar, based on their detection at 70μm or at shorther wavelengths, and 218 as starless, because of non-detections at 70μm. For two other sources, we do not provide a secure classification, but suggest they are Class 0 protostars. Results. From the SED fitting we derived key physical parameters (i.e. mass, temperature, bolometric luminosity). Protostellar sources are in general warmer (T=12.8 K) and more compact (diameter=0.040 pc) than starless sources (T=10.3 K, diameter=0.067 pc). Both these findings can be ascribed to the presence of an internal source(s) of moderate heating, which also causes a temperature gradient and hence a more peaked intensity distribution. Moreover, the reduced dimensions of protostellar sources may indicate that they will not fragment further. A virial analysis of the starless sources gives an upper limit of 90% probability for the sources to be gravitationally bound and therefore prestellar in nature. A luminosity vs. mass diagram of the two populations shows that protostellar sources are in the early accretion phase, while prestellar sources populate a region of the diagram where mass accretion has not started yet. We fitted a power law N(log M) ∝ M−1.1±0.2 to the linear portion of the mass distribution of prestellar sources. This is in between that typical of CO clumps and those of cores in nearby star-forming regions. We i DA - 2012/03/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6a642dd1-b18e-4a24-8548-457162671672 ER - TY - JOUR TI - Bacterial inhibition of methane clathrate hydrates formed in a stirred autoclave DO - 10.1021/ef301077m AU - Townson, Iwan AU - Walker, Virginia K. AU - Ripmeester, John A. AU - Englezos, Peter T2 - Energy & Fuels SN - 0887-0624 SN - 1520-5029 VL - 26 IS - 12 SP - 7170 EP - 7175 AB - The potential for hydrate inhibition in a stirred autoclave at a subcooling of 2.3 K has been tested on two bacterial isolates. Chryseobacterium sp. C14 survives multiple freeze–thaw events and inhibits ice recrystallization, and Escherichia coli has neither of these properties but is a biofilm producer. Both strains showed methane hydrate inhibition, with a significant reduction in total hydrate formed. Chryseobacterium delayed hydrate nucleating time, to a similar level found for the commercial kinetic inhibitor, polyvinylpyrrolidone (PVP; 0.2 wt %). However, in the presence of E. coli, in comparison to PVP, the time to nucleation was almost tripled and the hydrate growth rate was reduced by half. Because of the variation inherent with the microbial samples, likely a result of the complexities associated with varying cell numbers and metabolic activity, numerous experiments were required. Analysis of the distinct hydrate growth profiles shown by the two bacterial strains indicated that different molecular sources were likely responsible for the observed inhibition. As a working hypothesis, it is suggested that the inhibition observed by Chryseobacterium cultures was partially due to ice recrystallization inhibition properties, while that of E. coli may be due to secreted macromolecules and the effect of biofilm. DA - 2012/12/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c7e2a981-e22a-4ea6-8212-1ca7dc372c8a ER - TY - JOUR TI - Density functional theory investigation of the contributions of π–π stacking and hydrogen-bonding interactions to the aggregation of model asphaltene compounds DO - 10.1021/ef202010p AU - Da costa, Leonardo M. AU - Stoyanov, Stanislav R. AU - Gusarov, Sergey AU - Tan, Xiaoli AU - Gray, Murray R. AU - Stryker, Jeffrey M. AU - Tykwinski, Rik AU - de M. Carneiro, J. Walkimar AU - Seidl, Peter R. AU - Kovalenko, Andriy T2 - Energy & Fuels SN - 0887-0624 SN - 1520-5029 VL - 26 IS - 5 SP - 2727 EP - 2735 AB - We performed density functional theory (DFT) calculations using the WB97Xd functional with a dispersion correction term and the 6-31G(d,p) basis set to study the contributions of π–π stacking and hydrogen-bonding interactions to the aggregation of asphaltene model compounds containing a 2,2′-bipyridine moiety covalently bonded to one (monosubstituted) and two (disubstituted) aromatic hydrocarbon moieties (phenyl, naphthyl, anthracyl, phenanthryl, and pyrenyl) through ethylene tethers. In these compounds, the N atoms of the 2,2′-bipyridine moiety provide lone pairs for hydrogen bonding to water molecules present in solution. The aggregation strength of the homodimers of these model compounds is evaluated in terms of the aggregation energies, enthalpies, and ΔG²⁹⁸, as well as the π–π interaction distances. Geometry optimization and thermochemistry analysis results show that the homodimers of both mono- and disubstituted compounds are stable and have a negative ΔG²⁹⁸ of aggregation because of π–π stacking interactions. Two water bridges containing one, two, or three water molecules per bridge span between two monomers and provide additional stabilization of the homodimers because of hydrogen bonding. The stabilization of the monosubstituted homodimers is the largest with two water molecules per bridge, whereas the stabilization of the disubstituted homodimers is the largest with three water molecules per bridge. The calculated ¹H nuclear magnetic resonance chemical shifts for the monomers and dimers of the three model compounds of this series synthesized to date are in excellent agreement with experimental results for dilute and concentrated solutions in chloroform, respectively (Tan, X.; Fenniri, H.; Gray, M. R.Water enhances the aggregation of model asphaltenes in solution via hydrogen bonding. Energy Fuels 2009, 23, 3687). The ΔH and ΔG²⁹⁸ results show that hydrogen bonding is as important as π–π interactions for asphaltene aggregation. DA - 2012/05/17 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 94761cd9-07f1-4778-8ff1-1c76832550fc ER - TY - JOUR TI - 3D-RISM-Dock: a new fragment-based drug design protocol DO - 10.1021/ct300257v AU - Nikolić, Dragan AU - Blinov, Nikolay AU - Wishart, David AU - Kovalenko, Andriy T2 - Journal of Chemical Theory and Computation SN - 1549-9618 SN - 1549-9626 VL - 8 IS - 9 SP - 3356 EP - 3372 AB - We explore a new approach in the rational design of specificity in molecular recognition of small molecules based on statistical-mechanical integral equation theory of molecular liquids in the form of the three-dimensional reference interaction site model with the Kovalenko–Hirata closure (3D-RISM-KH). The numerically stable iterative solution of conventional 3D-RISM equations includes the fragmental decomposition of flexible ligands, which are treated as distinct species in solvent mixtures of arbitrary complexity. The computed density functions for solution (including ligand) molecules are obtained as a set of discrete spatial grids that uniquely describe the continuous solvent-site distribution around the protein solute. Potentials of mean force derived from these distributions define the scoring function interfaced with the AutoDock program for an automated ranking of docked conformations. As a case study in terms of solvent composition, we analyze cooperative interactions encountered in the binding of a flexible thiamine molecule to the prion protein at near-physiological conditions. The predicted location and residency times of computed binding modes are in excellent agreement with the available experimental data. DA - 2012/09/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f6ecc755-d8d0-464f-84da-eab5431d12b3 ER - TY - JOUR TI - Overcoming the barrier on time step size in multiscale molecular dynamics simulation of molecular liquids DO - 10.1021/ct200157x AU - Omelyan, Igor P. AU - Kovalenko, Andriy T2 - Journal of Chemical Theory and Computation SN - 1549-9618 SN - 1549-9626 VL - 8 IS - 1 SP - 6 EP - 16 AB - We propose and validate a new multiscale technique, the extrapolative isokinetic Nóse–Hoover chain orientational (EINO) motion multiple time step algorithm for rigid interaction site models of molecular liquids. It nontrivially combines the multiple time step decomposition operator method with a specific extrapolation of intermolecular interactions, complemented by an extended isokinetic Nosé–Hoover chain approach in the presence of translational and orientational degrees of freedom. The EINO algorithm obviates the limitations on time step size in molecular dynamics simulations. While the best existing multistep algorithms can advance from a 5 fs single step to a maximum 100 fs outer step, we show on the basis of molecular dynamics simulations of the TIP4P water that our EINO technique overcomes this barrier. Specifically, we have achieved giant time steps on the order of 500 fs up to 5 ps, which now become available in the study of equilibrium and conformational properties of molecular liquids without a loss of stability and accuracy. DA - 2012/01/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0d7102fc-fdd4-41f1-b901-b1bd0bcc1460 ER - TY - JOUR TI - Bandpass filter implemented with blazed waveguide sidewall gratings in silicon-on-insulator DO - 10.1049/el.2012.0591 AU - Velasco, A. V. AU - Bock, P. J. AU - Cheben, P. AU - Calvo, M. L. AU - Schmid, J. H. AU - Lapointe, J. AU - Xu, D.-X. AU - Janz, S. AU - Delâge, A. T2 - Electronics Letters SN - 00135194 VL - 48 IS - 12 SP - 715 EP - 717 AB - The fabrication and experimental characterisation of a two-stage band-pass filter based on curved waveguide sidewall gratings is reported for the silicon-on-insulator platform. At each cascaded filtering stage, the spectral components of the input signal are dispersed by the diffraction grating formed in the sidewall of a silicon strip waveguide. Different wavelengths are focused onto different positions along the Rowland circle and the filter central wavelength is selected by a specific receiver waveguide. By using two consecutive filtering stages, both the filter passband profile and the stopband rejection ratio are substantially increased. The grating is apodised and chirped to ensure a constant effective index along the grating length to minimise phase distortions. Blazed geometry is used to maximise the diffraction efficiency to the −1st order. The device was fabricated with electron beam lithography and reactive ion etching using a single etch step. A bandwidth of 6.2 nm was measured near 1590 nm for the fabricated filter, with a roll-off of 4 dB/nm at the passband edge, and a stopband rejection of 40 dB. DA - 2012/06/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 25b39436-15d1-4c80-9e9e-1425999a8689 ER - TY - JOUR TI - Temperature dependence of gas-detection sensitivity of InGaAsSb/AlGaAsSb distributed feedback lasers at 2396 nm DO - 10.1049/el.2011.3369 AU - Ventrudo, B. F. AU - Storey, C. AU - Gupta, J. A. AU - Bezinger, A. T2 - Electronics Letters SN - 00135194 VL - 48 IS - 2 SP - 114 EP - 116 AB - The HF gas detection sensitivity of GaSb-based distributed feedback lasers was studied in order to evaluate the potential use of operating temperature to control the laser output power in field applications. Measurements were made in the 2f wavelength modulation spectroscopy mode to monitor a prominent HF absorption feature at 2396 nm. An Allan variance analysis indicates that the best sensitivity is obtained when a larger thermoelectric current is applied to maintain temperature control by actively heating or cooling the laser. The reduced detection sensitivity for a setpoint near the ambient laser operating temperature is similar to that obtained without active temperature control. DA - 2012/01/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b5b92450-949b-4416-b45f-654ce6701a59 ER - TY - JOUR TI - Partitioning of ethanol into lipid membranes and its effect on fluidity and permeability as seen by X-ray and neutron scattering DO - 10.1039/c2sm26546j AU - Toppozini, Laura AU - Armstrong, Clare L. AU - Barrett, Matthew A. AU - Zheng, Songbo AU - Luo, Lindy AU - Nanda, Hirsh AU - García Sakai, Victoria AU - Rheinstädter, Maikel C. T2 - Soft Matter SN - 1744-683X SN - 1744-6848 VL - 8 IS - 47 SP - 11839 EP - 11849 AB - We present a combined neutron and X-ray scattering investigation to study the effect of ethanol on the molecular structure and dynamics of lipid membranes. 1,2-Dimyristoyl-sn-glycero-3-phoshatidylcholine (DMPC) powder hydrated with a 5 wt% ethanol solution (corresponding to 2 mol% of ethanol) was used in this study. From high-resolution X-ray experiments the position and partitioning of the ethanol molecules in the phospholipid bilayers was determined in their gel and fluid phases. We find that the ethanol molecules reside in the head group region of the bilayers, with 1.6 ethanol molecules per lipid molecule in the gel phase and 1.2 ethanol molecules per lipid molecule in the fluid phase. We find evidence for enhanced permeability in both fluid and gel phases of the phospholipid bilayers in the presence of ethanol molecules. Elastic and quasi-elastic neutron scattering data, obtained using a neutron backscattering spectrometer, was used to study slow, nanosecond molecular dynamics on length scales corresponding to lipid diffusion, acyl chain dynamics and solvent dynamics. While the presence of ethanol molecules had no observable effect on these types of dynamics in the fluid (Lα) phase, the membranes appeared to have a higher degree of order in gel (Lβ) and ripple (Pβ′) phases. In particular, lipid diffusion was found to be slower by a factor of two in the more rigid gel phase when ethanol was present. DA - 2012/10/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5f68ff31-7903-4723-a29d-c5ab947153af ER - TY - JOUR TI - Synthesis and enzymatic evaluation of ketose phosphonates: the interplay between mutarotation, monofluorination and acidity DO - 10.1039/c2sc01077a AU - Forget, Stephanie M. AU - Bhattasali, Debabrata AU - Hart, V. Catherine AU - Cameron, T. Stanley AU - Syvitski, Ray T. AU - Jakeman, David L. T2 - Chemical Science SN - 2041-6520 SN - 2041-6539 VL - 3 IS - 6 SP - 1866 EP - 1878 AB - Ketose-phosphonates may adopt open chain, or α- or β-furanosyl, or α- or β-pyranosyl configurational isomers in aqueous solution. An HPLC and NMR analysis of a series of ketose-phosphonates with a thymidylyltransferase (dTDP-glucose pyrophosphorylase) implied a rapid dynamic equilibrium between the pyranosyl forms of gluco-ketose phosphonate leading to efficient production of unique sugar nucleotide analogues. The preparation of diastereomerically pure gluco-configured monofluoromethylenephosphonates enabled the determination of the thymidylyltransferase preference for CHF stereochemistry. The effects of acidity upon thymidylyltransferase substrate specificity were determined using a series of monofluoro- and difluoro- ketose-phosphonates. WaterLOGSY NMR spectroscopy demonstrated a switching of the ordered Bi-Bi mechanism with ketose-phosphonate substrates. Ketose-phosphonates are presented as a unique class of sugar 1-phosphate analogues with potential applications as glycosyltransferase probes. DA - 2012/03/16 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a5eed3d8-3eef-4700-8252-af257917ae3b ER - TY - JOUR TI - Perturbation induced formation of a 3D-network of microcrystals producing soft materials DO - 10.1039/c2ra20208e AU - Bardelang, David AU - Giorgi, Michel AU - Hornebecq, Virginie AU - Stepanov, Anatoli AU - Rizzato, Egon AU - Zaman, Md. Badruz AU - Chan, Gordon AU - Ouari, Olivier AU - Tordo, Paul T2 - RSC Advances SN - 2046-2069 VL - 2 IS - 13 SP - 5605 EP - 5609 AB - Toluene and 1-chloronaphthalene immobilization was observed when perturbing stimuli such as agitation or ultrasound are applied during the cooling of a hot supersaturated solution of the rigid dinitroxide bTbk. X-Ray diffraction and cryo-SEM on gels and solid samples (crystal, powder) confirmed the pivotal role of clathrate type microcrystals in the solvent immobilization process. DA - 2012/04/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d6ba138f-fd6b-48cb-9e10-5c489f4ea8b3 ER - TY - JOUR TI - Supercapacitive carbon nanotube-cobalt molybdate nanocomposites prepared via solvent-free microwave synthesis DO - 10.1039/c2ra01300b AU - Xu, Zhanwei AU - Li, Zhi AU - Tan, Xuehai AU - Holt, Chris M. B. AU - Zhang, Li AU - Amirkhiz, Babak Shalchi AU - Mitlin, David T2 - RSC Advances SN - 2046-2069 VL - 2 IS - 7 SP - 2753 EP - 2755 AB - Cobalt molybdate (CoMoO4) nanoplatelets with a crystalline-amorphous core-shell structure anchored via multi-walled carbon nanotubes were prepared by a solvent-free microwave synthesis method. The entire procedure took only 15 min. The nanocomposite shows a promising capacitance of 170 F g−¹ with a potential window of 0.8 V, degrading by only 6.8% after 1000 cycles. DA - 2012/01/16 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b6afe398-2972-4b5e-82e4-37166b086bc1 ER - TY - JOUR TI - Kinetics studies of rapid strain-promoted [3 + 2]-cycloadditions of nitrones with biaryl-aza-cyclooctynone DO - 10.1039/c2ob07165g AU - McKay, Craig S. AU - Chigrinova, Mariya AU - Blake, Jessie A. AU - Pezacki, John Paul T2 - Organic & Biomolecular Chemistry SN - 1477-0520 SN - 1477-0539 VL - 10 IS - 15 SP - 3066 EP - 3070 AB - Strain-promoted cycloadditions of cyclic nitrones with biaryl-aza-cyclooctynone (BARAC) proceed with rate constants up to 47.3 M−¹ s−¹, this corresponds to a 47-fold rate enhancement relative to reaction of BARAC with benzyl azide and a 14-fold enhancement over previously reported strain promoted alkyne–nitrone cycloadditions (SPANC). Studies of the SPANC reaction using the linear free energy relationship defined by the Hammett equation demonstrated that the cycloaddition reaction has a rho value of 0.25 ± 0.04, indicating that reaction is not sensitive to substituents and thus should have broad applicability. DA - 2012/02/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7053dfee-adb0-4474-95fa-5d1be1b2f7bf ER - TY - JOUR TI - Structure, ordering, and surfaces of Pt–Fe alloy catalytic nanoparticles from quantitative electron microscopy and X-ray diffraction DO - 10.1039/c2nr31509b AU - Chan, Mickey C. Y. AU - Chen, Liang AU - Nan, Feihong AU - Britten, James F. AU - Bock, Christina AU - Botton, Gianluigi A. T2 - Nanoscale SN - 2040-3364 SN - 2040-3372 VL - 4 IS - 22 SP - 7273 EP - 7279 AB - The current challenge in catalyst development is to produce highly active and economical catalysts. This challenge cannot be overcome without an accurate understanding of catalyst structure, surfaces and morphology as the catalytic reactions occur on the surface active sites. Transmission Electron Microscopy (TEM) is an excellent tool for understanding the structures of the nanoparticles down to the atomic level in determining the relationship with the catalyst's performance in fuel cell applications. This paper describes a detailed structural characterization of Pt–Fe nanoparticles using aberration corrected TEM. Detailed analysis regarding the morphology, structural ordering, facets, nature of the surfaces, atomic displacements and compositions was carried out and presented in the context of their electrochemical performances. In addition, the effects of electrochemical cycling in terms of morphology and composition evolution of the nanoparticles were analyzed. Lastly, along with data from X-ray diffractometry, two different crystallographic models of the unknown Pt3Fe2 nanoparticle phase are proposed. The detailed characterization by TEM provides useful insights into the nanoparticle chemistry and structure that contributes to catalyst development for next generation fuel cells. DA - 2012/10/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : abdb2980-e590-4e6d-b9e3-244dc1131f50 ER - TY - JOUR TI - An upstream interacting context based framework for the computational inference of microRNA functions DO - 10.1039/c2mb05469h AU - Qiu, Chengxiang AU - Wang, Dong AU - Wang, Edwin AU - Cui, Qinghua T2 - Molecular BioSystems SN - 1742-206X SN - 1742-2051 VL - 8 IS - 5 SP - 1492 EP - 1498 AB - With the rapid accumulation of microRNA (miRNAs), a class of newly identified small noncoding RNAs, in silico inference of miRNA functions has become one of the central tasks in miRNA bioinformatics. Traditional methods have helped in the understanding of miRNAs, but they also have limitations. In this paper, we first gave a brief review for the progress of bioinformatic methods in miRNA function inference and next presented a new framework (miRUPnet) for inferring the functions of miRNAs by functional analysis of a novel dimension of miRNA network, the context of its transcription factors (TFs) in a protein-protein interaction network. This dimension represents specific biological processes initiated by TF combinations and therefore differs from traditional methods in concept. To validate the accuracy of our method, we first comprehensively mined literature-reported miRNA functions and then made a comparison with the prediction result. The results show that even using the stringent TFBS rule, our method has independently predicted 68.2% of the literature reported miRNA functions, suggesting that miRUPnet has a high accuracy. Moreover, our approach successfully predicted specific functions that could not be inferred for given miRNAs using traditional methods. More importantly, it can distinguish miRNAs from the same family, as well as those present in multiple copies that cannot be differentiated through traditional methods. This study presents a new concept and dimension for miRNA function inference. miRUPnet represents an important and novel method for inferring the function of miRNAs. miRUPnet is available at http://cmbi.bjmu.edu.cn/mirupnet. DA - 2012/02/23 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7d656681-1f7f-4935-b221-1ecd3ac1bbb2 ER - TY - JOUR TI - Growth and positioning of adipose-derived stem cells in microfluidic devices DO - 10.1039/c2lc40891k AU - Wadhawan, Nitin AU - Kalkat, Harmandeep AU - Natarajan, Kanmani AU - Ma, Xiuli AU - Gajjeraman, Sivakumar AU - Nandagopal, Saravanan AU - Hao, Ning AU - Li, Jing AU - Zhang, Michael AU - Deng, Jixian AU - Xiang, Bo AU - Mzengeza, Shadreck AU - Freed, Darren H. AU - Arora, Rakesh C. AU - Tian, Ganghong AU - Lin, Francis T2 - Lab on a Chip SN - 1473-0197 SN - 1473-0189 VL - 12 IS - 22 SP - 4829 EP - 4834 AB - Stem cells hold great promise for treatment of various degenerative diseases. However, clinical studies have only shown very moderate benefits of cell therapy. We believe that insufficiency of therapeutic benefits is due to limited homing of implanted stem cells to targeted organs. Microfluidic devices are a very useful research tool for quantitative characterizations of stem cells. The present study therefore was to assess the effects of epidermal growth factor (EGF) and direct current electric field (dcEF) on the growth and trafficking of adipose-derived stem cells (ASC). It was found that EGF did not affect cell proliferation in cell-culture flasks. However, ASC proliferated at a higher rate in microfluidic devices with continuous infusion of EGF. Furthermore, we found that ASC migrated toward an EGF gradient in microfluidic devices. Moreover, we found that ASC tended to position perpendicularly to dcEF. The results suggest that EGF and dcEF may be effective in guiding homing and trafficking of implanted ASC. DA - 2012/09/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : db97ca83-7acd-441a-bec9-b871c5fdd813 ER - TY - JOUR TI - Microfluidic designs and techniques using lab-on-a-chip devices for pathogen detection for point-of-care diagnostics DO - 10.1039/c2lc40630f AU - Foudeh, Amir M. AU - Fatanat Didar, Tohid AU - Veres, Teodor AU - Tabrizian, Maryam T2 - Lab on a Chip SN - 1473-0197 SN - 1473-0189 VL - 12 IS - 18 SP - 3249 EP - 3266 AB - Effective pathogen detection is an essential prerequisite for the prevention and treatment of infectious diseases. Despite recent advances in biosensors, infectious diseases remain a major cause of illnesses and mortality throughout the world. For instance in developing countries, infectious diseases account for over half of the mortality rate. Pathogen detection platforms provide a fundamental tool in different fields including clinical diagnostics, pathology, drug discovery, clinical research, disease outbreaks, and food safety. Microfluidic lab-on-a-chip (LOC) devices offer many advantages for pathogen detection such as miniaturization, small sample volume, portability, rapid detection time and point-of-care diagnosis. This review paper outlines recent microfluidic based devices and LOC design strategies for pathogen detection with the main focus on the integration of different techniques that led to the development of sample-to-result devices. Several examples of recently developed devices are presented along with respective advantages and limitations of each design. Progresses made in biomarkers, sample preparation, amplification and fluid handling techniques using microfluidic platforms are also covered and strategies for multiplexing and high-throughput analysis, as well as point-of-care diagnosis, are discussed. DA - 2012/06/26 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d1b6946e-4792-4664-acc1-aaa08c79d737 ER - TY - JOUR TI - Fe3O4–silica core–shell nanoporous particles for high-capacity pH-triggered drug delivery DO - 10.1039/c2jm31749d AU - Zhang, X. F. AU - Mansouri, S. AU - Clime, L. AU - Ly, H. Q. AU - Yahia, L. 'H. AU - Veres, T. T2 - Journal of Materials Chemistry SN - 0959-9428 SN - 1364-5501 VL - 22 IS - 29 SP - 14450 EP - 14457 AB - We demonstrate a one-step procedure for the synthesis of Fe3O4–silica core–shell nanoparticles with hierarchically ultra-large pores independent of any post-treatment such as annealing and template-molecule removal. The nanoporous silica shells with available amine groups were functionalized by clickable linkers to produce pH-sensitive amides for regulating the release of an anti-cancer drug, doxorubicin (DOX). The loading amount of DOX reached up to 13.2 mg per 100 mg nanoparticles, 74.2% of which can be effectively released after 63 h at body temperature and pH 5 with decreased side effects. Such excellent features of these nanoparticles appear to arise from the integrated hierarchically ultra-large open-porosities and a homogeneous dispersibility in aqueous solution that has a great potential for their use as drug delivery systems. DA - 2012/05/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6ec18330-3207-467e-9dac-10ec3661b4d5 ER - TY - JOUR TI - Self-assembly of carboxylated polythiophene nanowires for improved bulk heterojunction morphology in polymer solar cells DO - 10.1039/c2jm30576c AU - Li, Weiwei AU - Worfolk, Brian J. AU - Li, Peng AU - Hauger, Tate C. AU - Harris, Kenneth D. AU - Buriak, Jillian M. T2 - Journal of Materials Chemistry SN - 0959-9428 SN - 1364-5501 VL - 22 IS - 22 SP - 11354 EP - 11363 AB - Conjugated regioregular poly[3-(5-carboxypentyl) thiophene-2,5-diyl] (P3CPenT), a derivative of poly(3-hexylthiophene) (P3HT), is introduced as a hole transport layer (HTL) for P3HT:PCBM plastic solar cells (PSCs). P3CPenT, a carboxyl-functionalized polythiophene, is insoluble in solvents typically used in the preparation of photoactive layers such as chloroform, chlorobenzene and dichlorobenzene, allowing successive processing of the photoactive layer without dissolution of the HTL. P3CPenT self-assembles into nanowires in DMSO solution and when cast as a film, reduces concentration gradients of P3HT:PCBM photoactive layers. P3HT:PCBM PSCs incorporating P3CPenT nanowires as the HTL have a higher fill factor (FF, 0.67) and power conversion efficiency (PCE, 3.7%) than devices with conventional PEDOT:PSS HTLs. DA - 2012/04/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b888a5dc-0e38-497a-be93-f7765bde6c33 ER - TY - JOUR TI - Bacteriophage based probes for pathogen detection DO - 10.1039/c2an35371g AU - Singh, Amit AU - Arutyunov, Denis AU - Szymanski, Christine M. AU - Evoy, Stephane T2 - The Analyst SN - 0003-2654 SN - 1364-5528 VL - 137 IS - 15 SP - 3405 EP - 3421 AB - Rapid and specific detection of pathogenic bacteria is important for the proper treatment, containment and prevention of human, animal and plant diseases. Identifying unique biological probes to achieve a high degree of specificity and minimize false positives has therefore garnered much interest in recent years. Bacteriophages are obligate intracellular parasites that subvert bacterial cell resources for their own multiplication and production of disseminative new virions, which repeat the cycle by binding specifically to the host surface receptors and injecting genetic material into the bacterial cells. The precision of host recognition in phages is imparted by the receptor binding proteins (RBPs) that are often located in the tail-spike or tail fiber protein assemblies of the virions. Phage host recognition specificity has been traditionally exploited for bacterial typing using laborious and time consuming bacterial growth assays. At the same time this feature makes phage virions or RBPs an excellent choice for the development of probes capable of selectively capturing bacteria on solid surfaces with subsequent quick and automatic detection of the binding event. This review focuses on the description of pathogen detection approaches based on immobilized phage virions as well as pure recombinant RBPs. Specific advantages of RBP-based molecular probes are also discussed. DA - 2012/05/16 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c2635f4e-631f-48a1-89a4-187433625bf8 ER - TY - JOUR TI - Highly corrosion resistant platinum–niobium oxide–carbon nanotube electrodes for the oxygen reduction in PEM fuel cells DO - 10.1039/c2ee02689a AU - Zhang, Li AU - Wang, Liya AU - Holt, Chris M. B. AU - Zahiri, Beniamin AU - Li, Zhi AU - Malek, Kourosh AU - Navessin, Titichai AU - Eikerling, Michael H. AU - Mitlin, David T2 - Energy & Environmental Science SN - 1754-5692 SN - 1754-5706 VL - 5 IS - 3 SP - 6156 EP - 6172 AB - Nanocomposite materials consisting of platinum deposited on carbon nanotubes are emerging electrocatalysts for the oxygen reduction reaction in PEM fuel cells. However, these materials albeit showing promising electrocatalytic activities suffer from unacceptable rates of corrosion during service. This study demonstrates an effective strategy for creating highly corrosion-resistant electrocatalysts utilizing metal oxide coated carbon nanotubes as a support for Pt. The electrode geometry consisted of a three-dimensional array of multi-walled carbon nanotubes grown directly on Inconel and conformally covered by a bilayer of Pt/niobium oxide. The activities of these hybrid carbon-metal oxide materials are on par with commercially available carbon-supported Pt catalysts. We show that a sub-nanometre interlayer of NbO2 provides effective protection from electrode corrosion. After 10,000 cyclic voltammetry cycles from 0.5 V to 1.4 V, the loss of electrochemical surface area, reduction of the half-wave potential, and the loss of specific activity of the NbO2 supported Pt were 10.8%, 8 mV and 10.3%, respectively. Under the same conditions, the catalytic layers with Pt directly deposited onto carbon nanotubes had a loss of electrochemical area, reduction of half-wave potential and loss of specific activity of 47.3%, 65 mV and 65.8%, respectively. The improved corrosion resistance is supported by microstructural observations of both electrodes in their post-cycled state. First principles calculations at the density functional theory level were performed to gain further insight into changes in wetting properties, stability and electronic structure introduced by the insertion of the thin NbO2 film. DA - 2012/02/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 02730b2e-801b-44ef-b5ca-227c99f4d5fb ER - TY - JOUR TI - American cranberry (Vaccinium macrocarpon) extract affects human prostate cancer cell growth via cell cycle arrest by modulating expression of cell cycle regulators DO - 10.1039/c2fo10145a AU - Déziel, Bob AU - MacPhee, James AU - Patel, Kunal AU - Catalli, Adriana AU - Kulka, Marianna AU - Neto, Catherine AU - Gottschall-Pass, Katherine AU - Hurta, Robert T2 - Food & Function SN - 2042-6496 SN - 2042-650X VL - 3 IS - 5 SP - 556 EP - 564 AB - Prostate cancer is one of the most common cancers in the world, and its prevalence is expected to increase appreciably in the coming decades. As such, more research is necessary to understand the etiology, progression and possible preventative measures to delay or to stop the development of this disease. Recently, there has been interest in examining the effects of whole extracts from commonly harvested crops on the behaviour and progression of cancer. Here, we describe the effects of whole cranberry extract (WCE) on the behaviour of DU145 human prostate cancer cells in vitro. Following treatment of DU145 human prostate cancer cells with 10, 25 and 50 μg ml−¹ of WCE, respectively for 6 h, WCE significantly decreased the cellular viability of DU145 cells. WCE also decreased the proportion of cells in the G2-M phase of the cell cycle and increased the proportion of cells in the G1 phase of the cell cycle following treatment of cells with 25 and 50 μg ml−¹ treatment of WCE for 6 h. These alterations in cell cycle were associated with changes in cell cycle regulatory proteins and other cell cycle associated proteins. WCE decreased the expression of CDK4, cyclin A, cyclin B1, cyclin D1 and cyclin E, and increased the expression of p27. Changes in p16INK4a and pRBp107 protein expression levels also were evident, however, the changes noted in p16INK4a and pRBp107 protein expression levels were not statistically significant. These findings demonstrate that phytochemical extracts from the American cranberry (Vaccinium macrocarpon) can affect the behaviour of human prostate cancer cells in vitro and further support the potential health benefits associated with cranberries. DA - 2012/03/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ea3993b3-dcc2-41fe-8e21-8b1980a4a3ff ER - TY - JOUR TI - Improved in situ Hf isotope ratio analysis of zircon using newly designed X skimmer cone and jet sample cone in combination with the addition of nitrogen by laser ablation multiple collector ICP-MS DO - 10.1039/c2ja30078h AU - Hu, Zhaochu AU - Liu, Yongsheng AU - Gao, Shan AU - Liu, Wengui AU - Zhang, Wen AU - Tong, Xirun AU - Lin, Lin AU - Zong, Keqing AU - Li, Ming AU - Chen, Haihong AU - Zhou, Lian AU - Yang, Lu T2 - Journal of Analytical Atomic Spectrometry SN - 0267-9477 SN - 1364-5544 VL - 27 IS - 9 SP - 1391 EP - 1399 AB - The effect of three different cone combinations on the performance of laser ablation MC-ICP-MS (Neptune plus) for the in situ Hf isotope analysis of zircon were investigated. The signal sensitivities of Hf, Yb and Lu were improved by a factor of 1.4 and 2.5, respectively, with using the X skimmer cone + standard sampler cone and the X skimmer cone + Jet sample cone compared to the standard arrangement (H skimmer cone + standard sample cone). However, when using the high-sensitivity Jet sample cone, the instrumental mass fractionation for hafnium displayed a large non-linear component that could not be corrected using the normal mass fractionation laws. The magnitude of this non-linear mass fractionation was strongly related to the central gas flow rate. The in situ Hf isotope analysis of zircon standards 91500 and Mud Tank using the Jet cone displayed large deviations (410–470 ppm) at the optimum central gas flow rate for Hf, which seriously deteriorated the performance of the Jet cone. The addition of 4 ml min−¹ nitrogen to the central gas flow in laser ablation MC-ICP-MS was found to not only increase the sensitivity of Hf by a factor of 2.1, but also suppress this non-linear mass fractionation. The determined Yb/Hf and Lu/Hf ratios at their corresponding optimum makeup gas flow rates for Hf intensity were found to be reduced by factors of 2 and 1.3 in the presence of nitrogen, respectively, which would benefit the accurate in situ determination of Hf isotopes in high-content Yb and Lu samples. Compared to the standard arrangement, the corresponding precision (2σ) of 176Hf/177Hf for single spot analysis of zircon standard 91500 was improved from 224 ppm to 50 ppm by using the newly designed X-skimmer cone and Jet sample cone in combination with the nitrogen addition technique. The determined 176Hf/177Hf ratios are in excellent agreement with published values in five reference zircon standards (91500, GJ-1, Mud Tank, Penglai and Plešovice). Our first Hf isotopic results from zircon standard M257 (0.281544 ± 0.000018; 2SD, n = 151) showed that it was fairly homogeneous in Hf isotopes. These results clearly demonstrate that the present analytical method has the potential to become an important tool for the pursuit of high-quality in situ Hf isotope data for zircons. DA - 2012/07/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e533b361-e2df-43a5-9ac9-3f1c6ffed97a ER - TY - JOUR TI - Cation exchange: A facile method to make NaYF4:Yb,Tm-NaGdF4 core–shell nanoparticles with a thin, tunable, and uniform shell DO - 10.1021/cm2036844 AU - Dong, Cunhai AU - Korinek, Andreas AU - Blasiak, Barbara AU - Tomanek, Boguslaw AU - Van veggel, Frank C. J. M. T2 - Chemistry of Materials SN - 0897-4756 SN - 1520-5002 VL - 24 IS - 7 SP - 1297 EP - 1305 KW - cation exchange; sodium lanthanide fluoride nanoparticles; core−shell nanoparticles; magnetic resonance imaging; up-conversion optical imaging AB - Cation exchange was performed on up-conversion NaYF4:Yb,Tm nanoparticles, resulting in NaYF4:Yb,Tm-NaGdF4 core–shell nanoparticles as indicated by electron energy-loss spectroscopy 2D mapping. Results show that core–shell nanoparticles with a thin, tunable, and uniform shell of subnanometer thickness can be made via this cation exchange process. The resulting NaYF4:Yb,Tm-NaGdF4 core–shell nanoparticles have an enhanced up-conversion intensity relative to the initial core nanoparticles. As potential magnetic resonance imaging (MRI) contrast agents, they were tested for their proton relaxivities. The r1 relaxivity per Gd³⁺ ion of the nanoparticles with a thin NaGdF4 shell (ca. 0.6 nm thick) measured at 9.4 T was found to be 2.33 mM–1·s–1. This r1 relaxivity is among the highest in all the reported NaYF4–NaGdF4 core–shell nanoparticles. The r1 relaxivity per nanoparticle is 1.56 × 104 mM–1·s–1, which is over 4000 times higher than commercial Gd³⁺-complexes. The very high proton relaxivity per nanoparticle is critical for targeted MRI as such nanoparticles provide strong contrast even in low concentrations. The presented cation exchange method is a promising way to manufacture core–shell nanoparticles with up-conversion NaYF4:Yb,Tm core and paramagnetic NaGdF4 shell for bimodal imaging, i.e. MR and optical imaging. DA - 2012/04/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5c0ff6d2-44f4-4413-a129-d412b43ed7a6 ER - TY - JOUR TI - Pb3TeCo3V2O14: A potential multiferroic Co bearing member of the dugganite series DO - 10.1021/cm202502p AU - Silverstein, H. J. AU - Cruz-kan, K. AU - Hallas, A. M. AU - Zhou, H. D. AU - Donaberger, R. L. AU - Hernden, B. C. AU - Bieringer, M. AU - Choi, E. S. AU - Hwang, J. M. AU - Wills, A. S. AU - Wiebe, C. R. T2 - Chemistry of Materials SN - 0897-4756 SN - 1520-5002 VL - 24 IS - 4 SP - 664 EP - 670 AB - Polycrystalline Pb3TeCo3V2O14, a structural analogue of the multiferroic Ba3NbFe3Si2O14, was synthesized and characterized using X-ray diffraction, magnetic susceptibility, specific heat, dielectric constant, and neutron diffraction. Magnetic susceptibility, specific heat capacity measurements, and bond valence analysis confirmed that the V5+ ion is nonmagnetic, while Co2+ is in its high spin state (S = 3/2). Two magnetic transitions were seen at TN1 = 8.6 K and TN2 = 6.0 K where the spins first adopt a magnetic structure with propagation vector k = (0.752,0,1/2) and reorder into a commensurate structure with propagation vector k = (5/6,5/6,1/2). Changes in the dielectric constant at both magnetic phase transitions suggest that magnetoelectric coupling exists in Pb3TeCo3V2O14. DA - 2012/02/28 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bd27cba2-5f61-4445-b22a-6f30e64bd466 ER - TY - JOUR TI - Nano-architecture and material designs for water splitting photoelectrodes DO - 10.1039/c2cs35019j AU - Chen, Hao Ming AU - Chen, Chih Kai AU - Liu, Ru-Shi AU - Zhang, Lei AU - Zhang, Jiujun AU - Wilkinson, David P. T2 - Chemical Society Reviews SN - 0306-0012 SN - 1460-4744 VL - 41 IS - 17 SP - 5654 EP - 5671 AB - This review concerns the efficient conversion of sunlight into chemical fuels through the photoelectrochemical splitting of water, which has the potential to generate sustainable hydrogen fuel. In this review, we discuss various photoelectrode materials and relative design strategies with their associated fabrication for solar water splitting. Factors affecting photoelectrochemical performance of these materials and designs are also described. The most recent progress in the research and development of new materials as well as their corresponding photoelectrodes is also summarized in this review. Finally, the research strategies and future directions for water splitting are discussed with recommendations to facilitate the further exploration of new photoelectrode materials and their associated technologies. DA - 2012/07/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 53d84fc8-d7cd-4594-8793-88f3e5160e97 ER - TY - JOUR TI - Body centered cubic magnesium niobium hydride with facile room temperature absorption and four weight percent reversible capacity DO - 10.1039/c2cp42136d AU - Tan, Xuehai AU - Wang, Liya AU - Holt, Chris M. B. AU - Zahiri, Beniamin AU - Eikerling, Michael H. AU - Mitlin, David T2 - Physical Chemistry Chemical Physics SN - 1463-9076 SN - 1463-9084 VL - 14 IS - 31 SP - 10904 EP - 10909 AB - We have synthesized a new metastable metal hydride with promising hydrogen storage properties. Body centered cubic (bcc) magnesium niobium hydride (Mg0.75Nb0.25)H2 possesses 4.5 wt% hydrogen gravimetric density, with 4 wt% being reversible. Volumetric hydrogen absorption measurements yield an enthalpy of hydride formation of −53 kJ mol−¹ H2, which indicates a significant thermodynamic destabilization relative to the baseline −77 kJ mol−¹ H2 for rutile MgH2. The hydrogenation cycling kinetics are remarkable. At room temperature and 1 bar hydrogen it takes 30 minutes to absorb a 1.5 μm thick film at sorption cycle 1, and 1 minute at cycle 5. Reversible desorption is achieved in about 60 minutes at 175 °C. Using ab initio calculations we have examined the thermodynamic stability of metallic alloys with hexagonal close packed (hcp) versus bcc crystal structure. Moreover we have analyzed the formation energies of the alloy hydrides that are bcc, rutile or fluorite. DA - 2012/06/27 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : dda04126-d142-4f04-be6f-e6ff57619079 ER - TY - JOUR TI - Flux engineering to control in-plane crystal and morphological orientation DO - 10.1021/cg300469s AU - Laforge, Joshua M. AU - Ingram, Grayson L. AU - Taschuk, Michael T. AU - Brett, Michael J. T2 - Crystal Growth & Design SN - 1528-7483 SN - 1528-7505 VL - 12 IS - 7 SP - 3661 EP - 3667 AB - We tailored nanostructured morphology and crystal texture of iron nanocolumns by engineering the inclination and azimuthal directions of the collimated flux characteristic of glancing angle deposition (GLAD). Under continuous substrate rotation, the flux is azimuthally isotropic within one rotation. With large substrate rotation speeds, we can deposit vertical nanocolumns with a faceted, tetrahedral apex, BCC crystal structure and 111 fiber texture. Designing the flux to have an azimuthal 3-fold symmetry, which reflects the symmetry of the tetrahedral apex, allows us to induce both an in-plane and out-of-plane texture (biaxial texture) by evolutionary selection. In-plane crystal orientation is accompanied by a preferential azimuthal nanocolumn orientation, where the sides of tetrahedral apex are directed toward the flux direction. This work demonstrates the flux engineering technique, which can orient in-plane crystal texture and morphology of crystalline nanocolumns on amorphous substrates. This control is a useful addition to vapor–solid, physical self-assembly with the potential to improve the performance of porous thin film architectures as biaxial buffer layers, and in a variety of device applications such as photovoltaics and energy storage. DA - 2012/07/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2851f4d7-c363-4f2c-809d-9146553d410c ER - TY - JOUR TI - The Paternò–Büchi reaction: importance of triplet states in the excited-state reaction pathway DO - 10.1039/c2cp40819h AU - Brogaard, Rasmus Y. AU - Schalk, Oliver AU - Boguslavskiy, Andrey E. AU - Enright, Gary D. AU - Hopf, Henning AU - Raev, Vitaly AU - Tarcoveanu, Eliza AU - Sølling, Theis I. AU - Stolow, Albert T2 - Physical Chemistry Chemical Physics SN - 1463-9076 SN - 1463-9084 VL - 14 IS - 24 SP - 8572 EP - 8580 AB - The Paternò–Büchi (PB) reaction between an excited carbonyl compound and an alkene has been widely studied, but so far little is known about the excited-state dynamics of the reaction. In this investigation, we used a compound in which a formyl and a vinyl group are attached to a [2.2]paracyclophane in order to obtain a model system in pre-reactive conformation for the PB reaction. We studied the excited-state dynamics of the isolated molecule in a molecular beam using femtosecond time-resolved photoelectron spectroscopy and ab initio calculations. The results show that inter-system crossing within two picoseconds competes efficiently with the reaction in the singlet manifold. Thus, the PB reaction in this model system takes place in the triplet state on a time scale of nanoseconds. This result stresses the importance of triplet states in the excited-state pathway of the PB reaction involving aromatic carbonyl compounds, even in situations in which the reacting moieties are in immediate vicinity. DA - 2012/05/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 74ec4d5a-837d-4b6e-bece-1f8d54c1f049 ER - TY - JOUR TI - Activity-Based Protein Profiling of the Escherichia coli GlpG Rhomboid Protein Delineates the Catalytic Core DO - 10.1021/bi301087c AU - Sherratt, Allison R. AU - Blais, David R. AU - Ghasriani, Houman AU - Pezacki, John Paul AU - Goto, Natalie K. T2 - Biochemistry SN - 0006-2960 SN - 1520-4995 VL - 51 IS - 39 SP - 7794 EP - 7803 AB - Rhomboid proteins comprise the largest class of intramembrane protease known, being conserved from bacteria to humans. The functional status of these proteases is typically assessed through direct or indirect detection of peptide cleavage products. Although these assays can report on the ability of a rhomboid to catalyze peptide bond cleavage, differences in measured hydrolysis rates can reflect changes in the structure and activity of catalytic residues, as well as the ability of the substrate to access the active site. Here we show that a highly reactive and sterically unencumbered fluorophosphonate activity-based protein profiling probe can be used to report on the catalytic integrity of active site residues in the Escherichia coli GlpG protein. We used results obtained with this probe on GlpG in proteomic samples, in combination with a conventional assay of proteolytic function on purified samples, to identify residues that are located on the cytoplasmic side of the lipid bilayer that are required for maximal proteolytic activity. Regions tested include the 90-residue aqueous-exposed N-terminus that encompasses a globular structure that we have determined by solution nuclear magnetic resonance, along with residues on the cytoplasmic side of the transmembrane domain core. While in most cases mutation or elimination of these residues did not significantly alter the catalytic status of the GlpG active site, the lipid-facing residue Arg227 was found to be important for maintaining a catalytically competent active site. In addition, we found a functionally critical region outside the transmembrane domain (TMD) core that is required for maximal protease activity. This region encompasses an additional 8–10 residues on the N-terminal side of the TMD core that precedes the first transmembrane segment and was not previously known to play a role in rhomboid function. These findings highlight the utility of the activity-based protein profiling approach for the characterization of rhomboid function. DA - 2012/10/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f183fdaf-bd65-48e3-906e-6a7dbd743b97 ER - TY - JOUR TI - Infrared spectra of ethylene clusters: (C2D4)2 and (C2D4)3 DO - 10.1039/c2cp40597k AU - Rezaei, M. AU - Michaelian, K. H. AU - McKellar, A. R. W. AU - Moazzen-Ahmadi, N. T2 - Physical Chemistry Chemical Physics SN - 1463-9076 SN - 1463-9084 VL - 14 IS - 23 SP - 8415 EP - 8418 AB - Spectra of ethylene dimers and trimers are studied in the ν11 fundamental band region of C2D4 (≈2200 cm−¹) using a tuneable quantum cascade laser to probe a pulsed supersonic slit jet expansion. The dimer spectrum is that of a prolate symmetric top perpendicular band, with a distinctive appearance because the A rotational constant is almost exactly equal to six times the B constant. The analysis supports the previously determined cross-shaped dimer structure with D2d symmetry. An ethylene trimer has not previously been observed with rotational resolution. The spectrum is that of an oblate symmetric top parallel band. It leads to a proposed trimer structure which is barrel shaped and has C3h or C3 symmetry, with the ethylene monomer C–C axes approximately aligned along the trimer symmetry axis. DA - 2012/04/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b13d54a0-83ad-4930-9460-7760781d61c3 ER - TY - JOUR TI - Pressure amorphized ices – an atomistic perspective DO - 10.1039/c2cp40201g AU - Tse, John S. AU - Klug, Dennis D. T2 - Physical Chemistry Chemical Physics SN - 1463-9076 SN - 1463-9084 VL - 14 IS - 23 SP - 8255 EP - 8263 AB - We offer our viewpoint on the nature of amorphous ices produced by pressurization of crystalline ice Ih and the inter-relationship between them from an atomistic perspective. We argue that the transformation of high density amorphous (HDA) ice from crystalline ice is due to a mechanical process arising from the instability of the ice Ih structure. The densification of HDA upon thermal annealing under pressure is a relaxation process. The conversion of the densified amorphous ice to a lower density form (LDA) upon the release of pressure can be attributed to a similar process. It is speculated that amorphous ices are metastable frustrated structures due to the large activation barriers associated with proton reorientation in the formation of the underlying stable crystalline ice polymorphs. DA - 2012/04/23 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f3102a9b-a0e1-4a24-855d-bb8a6f8e8c2d ER - TY - JOUR TI - Nonlinear optics: high harmonics with a twist DO - 10.1038/nphys2415 AU - Patchkovskii, Serguei AU - Spanner, Michael T2 - Nature Physics SN - 1745-2473 SN - 1745-2481 VL - 8 IS - 10 SP - 707 EP - 708 AB - Optical vortices usually break up when they propagate through nonlinear media. Now, however, experiments show the helical structure of an infrared beam can survive a high-harmonic-generation process. This could lead to a table-top source of attosecond helical light pulses. DA - 2012/08/26 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e61beb35-101b-461b-ae20-72c29ee7e779 ER - TY - JOUR TI - Quantum interference and phonon-mediated back-action in lateral quantum-dot circuits DO - 10.1038/nphys2326 AU - Granger, G. AU - Taubert, D. AU - Young, C. E. AU - Gaudreau, L. AU - Kam, A. AU - Studenikin, S. A. AU - Zawadzki, P. AU - Harbusch, D. AU - Schuh, D. AU - Wegscheider, W. AU - Wasilewski, Z. R. AU - Clerk, A. A. AU - Ludwig, S. AU - Sachrajda, A. S. T2 - Nature Physics SN - 1745-2473 SN - 1745-2481 VL - 8 IS - 7 SP - 522 EP - 527 AB - Spin qubits have been successfully realized in electrostatically defined, lateral few-electron quantum-dot circuits. Qubit readout typically involves spin to charge information conversion, followed by a charge measurement made using a nearby biased quantum point contact (QPC). It is critical to understand the back-action disturbances resulting from such a measurement approach. Previous studies have indicated that QPC detectors emit phonons which are then absorbed by nearby qubits. We report here the observation of a pronounced back-action effect in multiple dot circuits, where the absorption of detector-generated phonons is strongly modified by a quantum interference effect, and show that the phenomenon is well described by a theory incorporating both the QPC and coherent phonon absorption. Our combined experimental and theoretical results suggest strategies to suppress back-action during the qubit readout procedure. DA - 2012/06/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 233368d5-0387-4a2a-8587-7223352a8cbf ER - TY - JOUR TI - Spintronics: all-optical spin-wave control DO - 10.1038/nphoton.2012.241 AU - Freeman, Mark R. AU - Diao, Zhu T2 - Nature Photonics SN - 1749-4885 SN - 1749-4893 VL - 6 IS - 10 SP - 643 EP - 645 AB - Spin waves show promise as a means of transporting information in integrated magnetic devices, but convenient ways to control their properties are required. Now directional control of spin-wave emission using photonics has been demonstrated in an all-optical pump–probe experiment. DA - 2012/10/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 80e2b837-afda-4d06-b8f9-11017df50151 ER - TY - JOUR TI - Mapping coherence in measurement via full quantum tomography of a hybrid optical detector DO - 10.1038/nphoton.2012.107 AU - Zhang, Lijian AU - Coldenstrodt-Ronge, Hendrik B. AU - Datta, Animesh AU - Puentes, Graciana AU - Lundeen, Jeff S. AU - Jin, Xian-Min AU - Smith, Brian J. AU - Plenio, Martin B. AU - Walmsley, Ian A. SN - 1749-4885 SN - 1749-4893 VL - 6 IS - 6 SP - 364 EP - 368 KW - Quantum optics; Optoelectronic devices and components AB - Quantum states and measurements exhibit wave-like (continuous) or particle-like (discrete) character. Hybrid discrete–continuous photonic systems are key to investigating fundamental quantum phenomena, generating superpositions of macroscopic states, and form essential resources for quantum-enhanced applications such as entanglement distillation and quantum computation, as well as highly efficient optical telecommunications. Realizing the full potential of these hybrid systems requires quantum-optical measurements sensitive to non-commuting observables such as field quadrature amplitude and photon number. However, a thorough understanding of the practical performance of an optical detector interpolating between these two regions is absent. Here, we report the implementation of full quantum detector tomography, enabling the characterization of the simultaneous wave and photon-number sensitivities of quantum-optical detectors. This yields the largest parameterization to date in quantum tomography experiments, requiring the development of novel theoretical tools. Our results reveal the role of coherence in quantum measurements and demonstrate the tunability of hybrid quantum-optical detectors. DA - 2012/05/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a8d1d709-7e00-40bb-8165-72bc995a3cba ER - TY - JOUR TI - New magnetic phase diagram of (Sr,Ca)₂RuO₄ DO - 10.1038/nmat3236 AU - Carlo, J. P. AU - Goko, T. AU - Gat-Malureanu, I. M. AU - Russo, P. L. AU - Savici, A. T. AU - Aczel, A. A. AU - MacDougall, G. J. AU - Rodriguez, J. A. AU - Williams, T. J. AU - Luke, G. M. AU - Wiebe, C. R. AU - Yoshida, Y. AU - Nakatsuji, S. AU - Maeno, Y. AU - Taniguchi, T. AU - Uemura, Y. J. T2 - Nature Materials SN - 1476-1122 SN - 1476-4660 VL - 11 IS - 4 SP - 323 EP - 328 KW - Superconductors; Magnetic materials AB - High- Tc cuprates, iron pnictides, organic BEDT and TMTSF, alkali-doped C60, and heavy-fermion systems have superconducting states adjacent to competing states exhibiting static antiferromagnetic or spin density wave order. This feature has promoted pictures for their superconducting pairing mediated by spin fluctuations. Sr2RuO4 is another unconventional superconductor which almost certainly has a p-wave pairing. The absence of known signatures of static magnetism in the Sr-rich side of the (Ca, Sr) substitution space, however, has led to a prevailing view that the superconducting state in Sr2RuO4 emerges from a surrounding Fermi-liquid metallic state. Using muon spin relaxation and magnetic susceptibility measurements, we demonstrate here that (Sr,Ca)2RuO4 has a ground state with static magnetic order over nearly the entire range of (Ca, Sr) substitution, with spin-glass behaviour in Sr1.5Ca0.5RuO4 and Ca1.5Sr0.5RuO4. The resulting new magnetic phase diagram establishes the proximity of superconductivity in Sr2RuO4 to competing static magnetic order. DA - 2012/02/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 873391d8-e899-40c1-b25f-5470791b4c41 ER - TY - JOUR TI - Type I interferon induces necroptosis in macrophages during infection with Salmonella enterica serovar Typhimurium DO - 10.1038/ni.2397 AU - Robinson, Nirmal AU - McComb, Scott AU - Mulligan, Rebecca AU - Dudani, Renu AU - Krishnan, Lakshmi AU - Sad, Subash T2 - Nature Immunology SN - 1529-2908 SN - 1529-2916 VL - 13 IS - 10 SP - 954 EP - 962 AB - Salmonella enterica serovar Typhimurium (S. Typhimurium) is a virulent pathogen that induces rapid host death. Here we observed that host survival after infection with S. Typhimurium was enhanced in the absence of type I interferon signaling, with improved survival of mice deficient in the receptor for type I interferons (Ifnar1−/− mice) that was attributed to macrophages. Although there was no impairment in cytokine expression or inflammasome activation in Ifnar1−/− macrophages, they were highly resistant to S. Typhimurium–induced cell death. Specific inhibition of the kinase RIP1 or knockdown of the gene encoding the kinase RIP3 prevented the death of wild-type macrophages, which indicated that necroptosis was a mechanism of cell death. Finally, RIP3-deficient macrophages, which cannot undergo necroptosis, had similarly less death and enhanced control of S. Typhimurium in vivo. Thus, we propose that S. Typhimurium induces the production of type I interferon, which drives necroptosis of macrophages and allows them to evade the immune response. DA - 2012/08/26 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3ebd4629-ea09-40fe-a5ca-84c0f4061ba1 ER - TY - JOUR TI - Localizing internal friction along the reaction coordinate of protein folding by combining ensemble and single-molecule fluorescence spectroscopy DO - 10.1038/ncomms2204 AU - Borgia, Alessandro AU - Wensley, Beth G. AU - Soranno, Andrea AU - Nettels, Daniel AU - Borgia, Madeleine B. AU - Hoffmann, Armin AU - Pfeil, Shawn H. AU - Lipman, Everett A. AU - Clarke, Jane AU - Schuler, Benjamin T2 - Nature Communications SN - 2041-1723 VL - 3 SP - 1195 AB - Theory, simulations and experimental results have suggested an important role of internal friction in the kinetics of protein folding. Recent experiments on spectrin domains provided the first evidence for a pronounced contribution of internal friction in proteins that fold on the millisecond timescale. However, it has remained unclear how this contribution is distributed along the reaction and what influence it has on the folding dynamics. Here we use a combination of single-molecule Förster resonance energy transfer, nanosecond fluorescence correlation spectroscopy, microfluidic mixing and denaturant- and viscosity-dependent protein-folding kinetics to probe internal friction in the unfolded state and at the early and late transition states of slow- and fast-folding spectrin domains. We find that the internal friction affecting the folding rates of spectrin domains is highly localized to the early transition state, suggesting an important role of rather specific interactions in the rate-limiting conformational changes. DA - 2012/11/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1da9f759-09e0-4023-86c7-0456fffa8971 ER - TY - JOUR TI - Comet-like mineralogy of olivine crystals in an extrasolar proto-Kuiper belt DO - 10.1038/nature11469 AU - De Vries, B. L. AU - Acke, B. AU - Blommaert, J. A. D. L. AU - Waelkens, C. AU - Waters, L. B. F. M. AU - Vandenbussche, B. AU - Min, M. AU - Olofsson, G. AU - Dominik, C. AU - Decin, L. AU - Barlow, M. J. AU - Brandeker, A. AU - Di Francesco, J. AU - Glauser, A. M. AU - Greaves, J. AU - Harvey, P. M. AU - Holland, W. S. AU - Ivison, R. J. AU - Liseau, R. AU - Pantin, E. E. AU - Pilbratt, G. L. AU - Royer, P. AU - Sibthorpe, B. SN - 0028-0836 SN - 1476-4687 VL - 490 IS - 7418 SP - 74 EP - 76 AB - Some planetary systems harbour debris disks containing planetesimals such as asteroids and comets. Collisions between such bodies produce small dust particles, the spectral features of which reveal their composition and, hence, that of their parent bodies. A measurement of the composition of olivine crystals (Mg2−2xFe2xSiO4) has been done for the protoplanetary disk HD 100546 and for olivine crystals in the warm inner parts of planetary systems. The latter compares well with the iron-rich olivine in asteroids (x ≈ 0.29). In the cold outskirts of the β Pictoris system, an analogue to the young Solar System, olivine crystals were detected but their composition remained undetermined, leaving unknown how the composition of the bulk of Solar System cometary olivine grains compares with that of extrasolar comets. Here we report the detection of the 69-micrometre-wavelength band of olivine crystals in the spectrum of β Pictoris. Because the disk is optically thin, we can associate the crystals with an extrasolar proto-Kuiper belt a distance of 15–45 astronomical units from the star (one astronomical unit is the Sun–Earth distance), determine their magnesium-rich composition (x = 0.01 ± 0.001) and show that they make up 3.6 ± 1.0 per cent of the total dust mass. These values are strikingly similar to those for the dust emitted by the most primitive comets in the Solar System, even though β Pictoris is more massive and more luminous and has a different planetary system architecture. DA - 2012/10/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 237b7418-d46a-4a17-901c-ca754f08d506 ER - TY - JOUR TI - Resolving the time when an electron exits a tunnelling barrier DO - 10.1038/nature11025 AU - Shafir, Dror AU - Soifer, Hadas AU - Bruner, Barry D. AU - Dagan, Michal AU - Mairesse, Yann AU - Patchkovskii, Serguei AU - Ivanov, Misha Yu. AU - Smirnova, Olga AU - Dudovich, Nirit SN - 0028-0836 SN - 1476-4687 VL - 485 IS - 7398 SP - 343 EP - 346 AB - The tunnelling of a particle through a barrier is one of the most fundamental and ubiquitous quantum processes. When induced by an intense laser field, electron tunnelling from atoms and molecules initiates a broad range of phenomena such as the generation of attosecond pulses, laser-induced electron diffraction and holography. These processes evolve on the attosecond timescale (1 attosecond ≡ 1 as = 10−^18 seconds) and are well suited to the investigation of a general issue much debated since the early days of quantum mechanics5, 6, 7—the link between the tunnelling of an electron through a barrier and its dynamics outside the barrier. Previous experiments have measured tunnelling rates with attosecond time resolution and tunnelling delay times. Here we study laser-induced tunnelling by using a weak probe field to steer the tunnelled electron in the lateral direction and then monitor the effect on the attosecond light bursts emitted when the liberated electron re-encounters the parent ion. We show that this approach allows us to measure the time at which the electron exits from the tunnelling barrier. We demonstrate the high sensitivity of the measurement by detecting subtle delays in ionization times from two orbitals of a carbon dioxide molecule. Measurement of the tunnelling process is essential for all attosecond experiments where strong-field ionization initiates ultrafast dynamics. Our approach provides a general tool for time-resolving multi-electron rearrangements in atoms and molecules—one of the key challenges in ultrafast science. DA - 2012/05/16 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8af969d2-47e1-4802-9f3a-0799698c6373 ER - TY - JOUR TI - Pathophysiology of the neurovascular unit: disease cause or consequence? DO - 10.1038/jcbfm.2012.25 AU - Stanimirovic, Danica b AU - Friedman, Alon T2 - Journal of Cerebral Blood Flow & Metabolism SN - 0271-678X SN - 1559-7016 VL - 32 IS - 7 SP - 1207 EP - 1221 KW - Alzheimer's disease; blood–brain barrier; genetic vasculopathies; migraine; neurovascular unit; seizures AB - Pathophysiology of the neurovascular unit (NVU) is commonly seen in neurological diseases. The typical features of NVU pathophysiology include tissue hypoxia, inflammatory and angiogenic activation, as well as initiation of complex molecular interactions between cellular (brain endothelial cells, astroctyes, pericytes, inflammatory cells, and neurons) and acellular (basal lamina) components of the NVU, jointly resulting in increased blood–brain barrier permeability, brain edema, neurovascular uncoupling, and neuronal dysfunction and damage. The evidence of important role of the brain vascular compartment in disease pathogenesis has elicited the debate whether the primary vascular events may be a cause of the neurological disease, as opposed to a mere participant recruited by a primary neuronal origin of pathology? Whereas some hereditary and acquired cerebral angiopathies could be considered a primary cause of neurological symptoms of the disease, the epidemiological studies showing a high degree of comorbidity among vascular disease and dementias, including Alzheimer's disease, as well as migraine and epilepsy, suggested that primary vascular pathology may be etiological factor causing neuronal dysfunction or degeneration in these diseases. This review focuses on recent hypotheses and evidence, suggesting that pathophysiology of the NVU may be initiating trigger for neuronal pathology and subsequent neurological manifestations of the disease. DA - 2012/03/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 45393d67-ec64-4373-82a4-371cbc77b25f ER - TY - JOUR TI - cIAP1 and cIAP2 limit macrophage necroptosis by inhibiting Rip1 and Rip3 activation DO - 10.1038/cdd.2012.59 AU - McComb, S. AU - Cheung, H. H. AU - Korneluk, R. G. AU - Wang, S. AU - Krishnan, L. AU - Sad, S. T2 - Cell Death & Differentiation SN - 1350-9047 SN - 1476-5403 VL - 19 IS - 11 SP - 1791 EP - 1801 KW - innate immunity; macrophage; inflammation; host–pathogen interactions AB - Cellular inhibitor of apoptosis proteins (cIAPs) have emerged as important anti-cell death mediators, particularly in cancer. Although they are known to be expressed in immune tissue, their specific immune function remains unclear. We observed that degradation of cIAPs with SMAC mimetic (SM) results in death of primary bone-marrow-derived macrophages. SM-induced death of macrophages occurred by programmed necrosis (necroptosis), which was dependent on TNF receptor expression. Consistent with necroptosis, SM-induced death of macrophages was abrogated by inhibition of receptor interacting protein 1 (Rip1) kinase signaling or by receptor interacting protein 3 (Rip3) knockdown. SM-induced necroptosis was also dependent on inhibition of SM-induced apoptosis due to the expression of the endogenous caspase inhibitor, xIAP. We found that cIAPs limit Rip3, and to a lesser extent Rip1, expression via post-transcriptional mechanisms, leading to inhibition of the Rip1–Rip3 death complex (necrosome). Reduced cIAP activity in vivo, via SM treatment or specific knockout of either cIAP, resulted in elevated macrophage cell death and compromised control of an intracellular bacterium, Listeria monocytogenes. These results show that cIAPs have an important role in limiting programmed necrosis of macrophages, which facilitates effective control of a pathogen. DA - 2012/05/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0a43c3fc-109b-4cf4-9398-072c8b08570a ER - TY - JOUR TI - The dependence of ice microphysics on aerosol concentration in arctic mixed-phase stratus clouds during ISDAC and M-PACE DO - 10.1029/2012JD017668 AU - Jackson, Robert C. AU - Mcfarquhar, Greg M. AU - Korolev, Alexei V. AU - Earle, Michael E. AU - Liu, Peter S. K. AU - Lawson, R. Paul AU - Brooks, Sarah AU - Wolde, Mengistu AU - Laskin, Alexander AU - Freer, Matt T2 - Journal of Geophysical Research SN - 0148-0227 VL - 117 IS - D15 KW - arctic clouds;cloud aerosol interactions;mixed phase clouds AB - Cloud and aerosol data acquired by the National Research Council of Canada (NRC) Convair-580 aircraft in, above, and below single-layer arctic stratocumulus cloud during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in April 2008 were used to test three aerosol indirect effects hypothesized to act in mixed-phase clouds: the riming indirect effect, the glaciation indirect effect, and the thermodynamic indirect effect. The data showed a correlation of R = 0.78 between liquid drop number concentration, Nliq inside cloud and ambient aerosol number concentration NPCASP below cloud. This, combined with increasing liquid water content LWC with height above cloud base and the nearly constant vertical profile of Nliq, suggested that liquid drops nucleated from aerosol at cloud base. No evidence of a riming indirect effect was observed, but a strong correlation of R = 0.69 between ice crystal number concentration Ni and NPCASP above cloud was noted. Increases in ice nuclei (IN) concentration with NPCASP above cloud for 2 flight dates combined with the subadiabatic LWC profiles suggest possible mixing of IN from cloud top consistent with the glaciation indirect effect. The lower Nice and lower effective radius rel for the more polluted ISDAC cases compared to data collected in cleaner single-layer stratocumulus conditions during the Mixed-Phase Arctic Cloud Experiment is consistent with the operation of the thermodynamic indirect effect. However, more data in a wider variety of meteorological and surface conditions, with greater variations in aerosol forcing, are required to identify the dominant aerosol forcing mechanisms in mixed-phase arctic clouds. DA - 2012/08/14 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fe588ae3-f8f5-498c-b589-a1c32a570ff8 ER - TY - JOUR TI - Protein profiling in potato (Solanum tuberosum L.) leaf tissues by differential centrifugation DO - 10.1021/pr201004k AU - Lim, Sanghyun AU - Chisholm, Kenneth AU - Coffin, Robert H. AU - Peters, Rick D. AU - Al-Mughrabi, Khalil I. AU - Wang-Pruski, Gefu AU - Pinto, Devanand M. T2 - Journal of Proteome Research SN - 1535-3893 SN - 1535-3907 VL - 11 IS - 4 SP - 2594 EP - 2601 KW - potato leaf; protein profiling; differential centrifugation; reproducibility; cell wall and cytoplasmic fractions AB - Foliar diseases, such as late blight, result in serious threats to potato production. As such, potato leaf tissue becomes an important substrate to study biological processes, such as plant defense responses to infection. Nonetheless, the potato leaf proteome remains poorly characterized. Here, we report protein profiling of potato leaf tissues using a modified differential centrifugation approach to separate the leaf tissues into cell wall and cytoplasmic fractions. This method helps to increase the number of identified proteins, including targeted putative cell wall proteins. The method allowed for the identification of 1484 nonredundant potato leaf proteins, of which 364 and 447 were reproducibly identified proteins in the cell wall and cytoplasmic fractions, respectively. Reproducibly identified proteins corresponded to over 70% of proteins identified in each replicate. A diverse range of proteins was identified based on their theoretical pI values, molecular masses, functional classification, and biological processes. Such a protein extraction method is effective for the establishment of a highly qualified proteome profile. DA - 2012/02/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d1841115-57a1-4b55-85ff-073d22268c15 ER - TY - JOUR TI - Isolation of steroidal glycosides from the Caribbean sponge Pandaros acanthifolium DO - 10.1021/np300520w AU - Berrué, Fabrice AU - Mcculloch, Malcolm W. B. AU - Boland, Patricia AU - Hart, Saskia AU - Harper, Mary Kay AU - Johnston, James AU - Kerr, Russell T2 - Journal of Natural Products SN - 0163-3864 SN - 1520-6025 VL - 75 IS - 12 SP - 2094 EP - 2100 AB - Four new steroidal glycosides, acanthifoliosides G–J (1–4), were isolated as minor constituents from the Caribbean marine sponge Pandaros acanthifolium. These metabolites are characterized by a highly oxygenated D ring and the presence of a disaccharide rhamnose-glucose residue and a rhamnose at positions C-3 and C-15, respectively. Their structures were established on the basis of extensive interpretation of 1D and 2D NMR data and HRESIMS analyses. The absolute configurations of the glucose and rhamnose sugars were determined by preparing aldose o-tolylthiocarbamate derivatives and comparison to authentic standards by LC/HRESIMS. Acanthifolioside G (1) exhibited antioxidant and cytoprotective activities. DA - 2012/12/17 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a210ab6b-656e-414d-a732-e732b4083cd6 ER - TY - JOUR TI - Ultraclean emission from InAsP quantum dots in defect-free wurtzite InP nanowires DO - 10.1021/nl303327h AU - Dalacu, Dan AU - Mnaymneh, Khaled AU - Lapointe, Jean AU - Wu, Xiaohua AU - Poole, Philip J. AU - Bulgarini, Gabriele AU - Zwiller, Val AU - Reimer, Michael E. T2 - Nano Letters SN - 1530-6984 SN - 1530-6992 VL - 12 IS - 11 SP - 5919 EP - 5923 KW - Nanowire; Qauntum dot; InAs/InP; Single photon source; Chemical beam epitaxy; Selective-area VLS growth AB - We report on the ultraclean emission from single quantum dots embedded in pure wurtzite nanowires. Using a two-step growth process combining selective-area and vapor–liquid–solid epitaxy, we grow defect-free wurtzite InP nanowires with embedded InAsP quantum dots, which are clad to diameters sufficient for waveguiding at λ 950 nm. The absence of nearby traps, at both the nanowire surface and along its length in the vicinity of the quantum dot, manifests in excitonic transitions of high spectral purity. Narrow emission line widths (30 μeV) and very-pure single photon emission with a probability of multiphoton emission below 1% are achieved, both of which were not possible in previous work where stacking fault densities were significantly higher. DA - 2012/11/14 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8104ff01-7bd2-49e9-9d30-d866f6b9a0b1 ER - TY - JOUR TI - UV-initiated hydrosilylation on hydrogen-terminated silicon (111): rate coefficient increase of two orders of magnitude in the presence of aromatic electron acceptors DO - 10.1021/la3035819 AU - Huck, Lawrence A. AU - Buriak, Jillian M. T2 - Langmuir SN - 0743-7463 SN - 1520-5827 VL - 28 IS - 47 SP - 16285 EP - 16293 AB - UV-initiated (254 nm) hydrosilylation of hexadecene on Si(111)-H has been studied in the presence of various aliphatic and aromatic molecules (additives). Many of these additives cause an enhancement in the pseudo-first-order rate coefficient (kobs) of hydrosilylation, some up to 200× faster than observed in neat hexadecene. It is proposed that these additives capture the photoejected electron from the surface, thereby increasing the probability of reaction of the alkene with the surface hole (h+), leading to Si–C bond formation. While the ability of these additives to increase kobs is related to their reduction potential, aromatic additives are particularly efficient; we suspect this is due to the relatively strong physisorption of the aromatic molecules leading to a favorable geometry for electron transfer. The presence of these additives permits the use of a much lower intensity of UV light (30 μW/cm²), reducing the probability of photodegradation of the monolayer, and maximum coverage can be reached within minutes. DA - 2012/10/29 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7f4c6b1b-1f09-47d9-97b6-3aef65f7f775 ER - TY - JOUR TI - Nonfouling hydrophilic poly(ethylene glycol) engraftment strategy for PDMS/SU-8 heterogeneous microfluidic devices DO - 10.1021/la303196m AU - Yeh, Po Ying AU - Zhang, Zhiyi AU - Lin, Min AU - Cao, Xudong T2 - Langmuir SN - 0743-7463 SN - 1520-5827 VL - 28 IS - 46 SP - 16227 EP - 16236 AB - We report a novel nonfouling passivation method using poly(ethylene glycol) (PEG) engraftment on the surfaces of poly(dimethylsiloxane) (PDMS) microfluidic devices sealed with SU-8. To achieve bonding between the PDMS and SU-8 surfaces, the PDMS surface was first functionalized with amines by treatment with 3-aminopropyltrimethoxysilane (APTMS) for subsequent reaction with epoxide functional groups on SU-8 surfaces. To modify the heterogeneous surfaces of the resulting PDMS/SU-8 microfluidic device further, the remaining SU-8 surfaces were amino functionalized using ethylene diamine (EDA), followed by treating both amino-functionalized PDMS and SU-8 surfaces with mPEG-NHS (N-hydroxysuccinimide) through an amine-NHS reaction for facile PEG immobilizations, thus simultaneously modifying both PDMS and SU-8 surfaces in one reaction. Detailed surface analyses such as the water contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) were conducted to confirm the chemical reactions and characterize the resulting surface properties. To test the efficacy of this surface-modification strategy, we conducted nonspecific protein and particle binding tests using microfluidic devices with and without modifications. The PEG-modified PDMS/SU-8 device surfaces showed a 64.5% reduction in nonspecific bovine serum albumin (BSA) adsorption in comparison to that of the unmodified surfaces and 92.0 and 95.8% reductions in microbead adhesion under both stagnant and flowing conditions, respectively. DA - 2012/10/30 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 842fde97-4d2f-4da5-a1b1-0aca031ae4fc ER - TY - JOUR TI - Spectroelectrochemical characterization of small hemoproteins adsorbed within nanostructured mesoporous ITO electrodes DO - 10.1021/la302913j AU - Schaming, Delphine AU - Renault, Christophe AU - Tucker, Ryan T. AU - Lau-Truong, Stéphanie AU - Aubard, Jean AU - Brett, Michael J. AU - Balland, Véronique AU - Limoges, Benoît T2 - Langmuir SN - 0743-7463 SN - 1520-5827 VL - 28 IS - 39 SP - 14065 EP - 14072 AB - 3D nanostructured transparent indium tin oxide (ITO) electrodes prepared by glancing angle deposition (GLAD) were used for the spectroelectrochemical characterization of cytochrome c (Cyt c) and neuroglobin (Nb). These small hemoproteins, involved as electron-transfer partners in the prevention of apoptosis, are oppositely charged at physiological pH and can each be adsorbed within the ITO network under different pH conditions. The resulting modified electrodes were investigated by UV–visible absorption spectroscopy coupled with cyclic voltammetry. By using nondenaturating adsorption conditions, we demonstrate that both proteins are capable of direct electron transfer to the conductive ITO surface, sharing apparent standard potentials similar to those reported in solution. Preservation of the 3D protein structure upon adsorption was confirmed by resonance Raman (rR) spectroscopy. Analysis of the derivative cyclic voltabsorptograms (DCVA) monitored either in the Soret or the Q bands at scan rates up to 1 V s–¹ allowed us to investigate direct interfacial electron transfer kinetics. From the DCVA shape and scan rate dependences, we conclude that the interaction of Cyt c with the ITO surface is more specific than Nb, suggesting an oriented adsorption of Cyt c and a random adsorption of Nb on the ITO surface. At the same time, Cyt c appears more sensitive to the experimental adsorption conditions, and complete denaturation of Cyt c may occur as evidenced from cross-correlation of rR spectroscopy and spectroelectrochemistry. DA - 2012/09/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 97486173-7ca0-4a51-b95d-018caf5c73f1 ER - TY - JOUR TI - Nitric oxide delivery by core/shell superparamagnetic nanoparticle vehicles with enhanced biocompatibility DO - 10.1021/la302357h AU - Zhang, X. F. AU - Mansouri, S. AU - Mbeh, D. A. AU - Yahia, L’H. AU - Sacher, E. AU - Veres, T. T2 - Langmuir SN - 0743-7463 SN - 1520-5827 VL - 28 IS - 35 SP - 12879 EP - 12885 AB - We report the synthesis of Fe3O4/silica core/shell nanoparticles and their functionalization with S-nitrosothiols. These nanoparticles are of immense interest because of their nitric oxide (NO) release capabilities in human alveolar epithelial cells. Moreover, they act as large storage reservoirs of NO that can be targeted magnetically to the specific site with a sustainable release of NO for up to 50 h. Such nanoparticles provide an enhancement of the biocompatibility with released NO while allowing intracellular accumulation ascribed to their small size. DA - 2012/08/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 42212114-dc41-4965-afbe-4b7fd27cc814 ER - TY - JOUR TI - A combined vibrational sum frequency generation spectroscopy and atomic force microscopy study of sphingomyelin–cholesterol monolayers DO - 10.1021/la301332e AU - Weeraman, Champika AU - Chen, Maohui AU - Moffatt, Douglas J. AU - Lausten, Rune AU - Stolow, Albert AU - Johnston, Linda J. T2 - Langmuir SN - 0743-7463 SN - 1520-5827 VL - 28 IS - 36 SP - 12999 EP - 13007 AB - A combination of vibrational sum frequency generation spectroscopy and atomic force microscopy is used to study the changes in morphology and conformational order in monolayers prepared from three natural sphingomyelin (SM) mixtures as a function of surface pressure and cholesterol concentration. The most homogeneous SM gave monolayers with well-ordered acyl chains and few gauche defects with relatively small effects of either increasing surface pressure or cholesterol addition. Heterogeneous SM mixtures with a mixture of acyl chain lengths or with significant fractions of unsaturated acyl chains had much larger contributions from gauche defects at low surface pressure and gave increasingly well-ordered monolayers as the surface pressure increased. They also showed substantial increases in lipid chain order after cholesterol addition. Overall, these results are consistent with the strong hydrogen bonding capacity of SM leading to well-ordered monolayers over a range of surface pressures. The changes in acyl chain order for natural SMs as a function of cholesterol are relevant to formation of sphingolipid–cholesterol enriched domains in cell membranes. DA - 2012/08/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c0cf24dd-44f5-4cb9-834e-08a1727b427b ER - TY - JOUR TI - Dispersions of nanocrystalline cellulose in aqueous polymer solutions: structure formation of colloidal rods DO - 10.1021/la2035449 AU - Boluk, Yaman AU - Zhao, Liyan AU - Incani, Vanessa T2 - Langmuir SN - 0743-7463 SN - 1520-5827 VL - 28 IS - 14 SP - 6114 EP - 6123 AB - The steady-state shear and linear viscoelastic deformations of semidilute suspensions of rod-shaped nanocrystalline cellulose (NCC) particles in 1.0% hydroxyethyl cellulose and carboxymethyl cellulose solutions were investigated. Addition of NCC at the onset of semidilute suspension concentration significantly altered the rheological and linear viscoelastic properties of semidilute polymer solutions. The low-shear viscosity values of polymers solutions were increased 20–490 times (depending on polymer molecular weight and functional groups) by the presence of NCC. NCC suspensions in polymer solutions exhibited yield stresses up to 7.12 Pa. Viscoelasticity measurements also showed that NCC suspended polymer solutions had higher linear elastic moduli than the loss moduli. All of those results revealed the gel formation of NCC particles and presence of internal structures. The formation of a weak gel structure was due to the nonadsorbing macromolecules which caused the depletion-induced interaction among NCC particles. A simple interaction energy model was used to show successfully the flocculation of NCC particles in the presence of nonadsorbing polymers. The model is based on the incorporation of the depletion interaction term between two parallel plates into the DLVO theory for cubic prismatic rod shaped NCC particles. DA - 2012/03/26 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c4b82e4e-fd79-4028-9551-5f9a0a7bcbd8 ER - TY - JOUR TI - Superparamagnetic microspheres with controlled macroporosity generated in microfluidic devices DO - 10.1021/am301304h AU - Paquet, Chantal AU - Jakubek, Zygmunt J. AU - Simard, Benoit T2 - ACS Applied Materials & Interfaces SN - 1944-8244 SN - 1944-8252 VL - 4 IS - 9 SP - 4934 EP - 4941 KW - microfluidic; superparamagnetic; porous; microparticles; assembly; magnetic separation AB - A microfluidic approach to preparing superparamagnetic microspheres with tunable porosity is described. In this method, droplets consisting of iron oxide nanoparticles, a functional polymer and solvent are formed in a microfluidic channel. The droplets are subsequently collected in solutions of sodium dodecyl sulfate (SDS) where the solvent is left to diffuse out of the droplet phase. By adjusting the concentration of the SDS and the polarity of the solvent of the dispersed phase, the porosity of the microparticles is controlled from non porous to porous structure. The formation of the pores is shown to depend on the rate at which solvent diffuses out of the droplet phase and the availability of SDS to adsorb at the droplet interface. DA - 2012/09/26 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fff33f85-804c-4cf0-afab-434efe095722 ER - TY - JOUR TI - Electrochemical supercapacitor electrodes from sponge-like graphene nanoarchitectures with ultrahigh power density DO - 10.1021/jz301207g AU - Xu, Zhanwei AU - Li, Zhi AU - Holt, Chris M. B. AU - Tan, Xuehai AU - Wang, Huanlei AU - Amirkhiz, Babak Shalchi AU - Stephenson, Tyler AU - Mitlin, David T2 - The Journal of Physical Chemistry Letters SN - 1948-7185 VL - 3 IS - 20 SP - 2928 EP - 2933 KW - electrochemical capacitor; three-dimensional; graphene; carbon nanotube; microwave AB - We employed a microwave synthesis process of cobalt phthalocyanine molecules templated by acid-functionalized multiwalled carbon nanotubes to create three-dimensional sponge-like graphene nanoarchitectures suited for ionic liquid-based electrochemical capacitor electrodes that operate at very high scan rates. The sequential “bottom-up” molecular synthesis and subsequent carbonization process took less than 20 min to complete. The 3D nanoarchitectures are able to deliver an energy density of 7.1 W·h kg–¹ even at an extra high power density of 48 000 W kg–¹. In addition, the ionic liquid supercapacitor based on this material works very well at room temperature due to its fully opened structures, which is ideal for the high-power energy application requiring more tolerance to temperature variation. Moreover, the structures are stable in both ionic liquids and 1 M H2SO4, retaining 90 and 98% capacitance after 10 000 cycles, respectively. DA - 2012/10/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 242f5d0a-1503-4fc0-840e-6e1ea0a2c0df ER - TY - JOUR TI - Multifunctional resistive-heating and color-changing monofilaments produced by a single-step coaxial melt-spinning process DO - 10.1021/am300491x AU - Laforgue, Alexis AU - Rouget, Geoffroy AU - Dubost, Sylvain AU - Champagne, Michel F. AU - Robitaille, Lucie T2 - ACS Applied Materials & Interfaces SN - 1944-8244 SN - 1944-8252 VL - 4 IS - 6 SP - 3163 EP - 3168 KW - monofilament; melt-spinning; multifunctional; electrochromic; color change; resistive heating; coaxial monofilament; smart textile AB - Multifunctional coaxial monofilaments were successfully produced by melt-spinning several polymer composites in a single-step. The external layer of the monofilaments was a thermochromic composite having a color-transition at 40 °C (above the ambient temperature) in order to avoid control interferences by the external temperature. The core layer of the monofilaments was a conductive polymer nanocomposite whose resistive heating properties were used to control the monofilament’s temperature and therefore its color using electrical current. The careful selection of the materials and adequate formulation allowed to obtain a trilayer structure with enhanced compatibility between the layers. The mechanical properties of the monofilaments were improved by a solid-state stretching step while also decreasing their diameter. A 64 cm ³ prototype fabric was woven to characterize the resistive-heating and color-changing properties of the monofilaments. Exceptional thermal output levels were reached, with a temperature rising up to over 100 °C at voltages above 110 V. The reversible color change properties were also successfully demonstrated. DA - 2012/06/27 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 209f25bc-3bbb-4347-9477-303e1e462f36 ER - TY - JOUR TI - A (nearly) universally applicable method for modeling noncovalent interactions using B3LYP DO - 10.1021/jz300554y AU - Torres, Edmanuel AU - DiLabio, Gino A. T2 - The Journal of Physical Chemistry Letters SN - 1948-7185 VL - 3 IS - 13 SP - 1738 EP - 1744 KW - dispersion-corrected density-functional theory; B3LYP; dispersion-correcting potentials; B3LYP-DCP; accurate noncovalent binding energies AB - B3LYP is the most widely used density-functional theory (DFT) approach because it is capable of accurately predicting molecular structures and other properties. However, B3LYP is not able to reliably model systems in which noncovalent interactions are important. Here we present a method that corrects this deficiency in B3LYP by using dispersion-correcting potentials (DCPs). DCPs are utilized by simple modifications to input files and can be used in any computational package that can read effective-core potentials. Therefore, the technique requires no programming. DCPs (developed for H, C, N, and O) produce the best results when used in conjunction with 6-31+G(2d,2p) basis sets. The B3LYP-DCP approach was tested on the S66, S22, and HSG-A benchmark sets of noncovalently interacting dimers and trimers and was found to, on average, significantly outperform almost all other DFT-based methods that were designed to treat van der Waals interactions. Users of B3LYP who wish to model systems in which noncovalent interactions (viz., steric repulsion, hydrogen bonding, π-stacking) are present, should consider B3LYP-DCP. DA - 2012/07/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7673576c-b25e-4f8f-9d40-9b24375413bc ER - TY - JOUR TI - NaDyF4 nanoparticles as T2 contrast agents for ultrahigh field magnetic resonance imaging DO - 10.1021/jz201664h AU - Das, Gautom Kumar AU - Johnson, Noah J. J. AU - Cramen, Jordan AU - Blasiak, Barbara AU - Latta, Peter AU - Tomanek, Boguslaw AU - van Veggel, Frank C. J. M. T2 - The Journal of Physical Chemistry Letters SN - 1948-7185 VL - 3 IS - 4 SP - 524 EP - 529 AB - A major limitation of the commonly used clinical MRI contrast agents (CAs) suitable at lower magnetic field strengths (<3.0 T) is their inefficiency at higher fields (>7 T), where next-generation MRI scanners are going. We present dysprosium nanoparticles (β-NaDyF4 NPs) as T2 CAs suitable at ultrahigh fields (9.4 T). These NPs effectively enhance T2 contrast at 9.4 T, which is 10-fold higher than the clinically used T2 CA (Resovist). Evaluation of the relaxivities at 3 and 9.4 T show that the T2 contrast enhances with an increase in NP size and field strength. Specifically, the transverse relaxivity (r2) values at 9.4 T were 64 times higher per NP (20.3 nm) and 6 times higher per Dy3+ ion compared to that at 3 T, which is attributed to the Curie spin relaxation mechanism. These results and confirming phantom MR images demonstrate their effectiveness as T2 CAs in ultrahigh field MRIs. DA - 2012/02/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a08cbca3-f8a0-4521-a3ff-7971d8034220 ER - TY - JOUR TI - Influence of hydrated silica surfaces on interfacial water in the presence of clathrate hydrate forming gases DO - 10.1021/jp305529d AU - Bagherzadeh, S. Alireza AU - Englezos, Peter AU - Alavi, Saman AU - Ripmeester, John A. T2 - The Journal of Physical Chemistry C SN - 1932-7447 SN - 1932-7455 VL - 116 IS - 47 SP - 24907 EP - 24915 AB - We study the hydrated silica–water interface in the presence of methane or carbon dioxide gas with molecular dynamics simulations. The simulations are performed with a limited amount of water, which forms a meniscus between two hydroxylated silica surfaces separated by 40 to 60 Å. Simulations were performed with the remaining space of the simulation cell left empty or filled with different numbers of methane or carbon dioxide gas molecules. The meniscus is used to determine the contact angle between water and silica in the absence and presence of the gases. The distribution profiles of the water and gas phases are determined over the duration of the simulation. The water number density in the layers adjacent to the silica is higher, and these layers are more structured and less mobile compared with water layers far from the surface. Additionally, the concentrations of the gases are significantly higher at the liquid and silica interfaces than in other locations in the gas phase. We speculate that the enhanced concentration of gases at the interface along with the extended contact area (curved meniscus compared with flat interface in the absence of silica surfaces) between water and guest molecules at the meniscus as well as lesser mobility of water molecules near the silica surface may provide a mechanism for the heterogeneous nucleation of the clathrate hydrate in water-wetting porous medium. DA - 2012/11/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 12b63578-7c99-4fe2-89cd-03a78ffde4ad ER - TY - JOUR TI - Molecular simulation of gas transport in hydrated nafion membranes: influence of aqueous nanostructure DO - 10.1021/jp305464r AU - Ban, Shuai AU - Huang, Cheng AU - Yuan, Xiao-Zi AU - Wang, Haijiang T2 - The Journal of Physical Chemistry C SN - 1932-7447 SN - 1932-7455 VL - 116 IS - 33 SP - 17424 EP - 17430 AB - Molecular simulation was used to investigate the nanoporous structure of hydrated Nafion membrane and its impact on gas transport. The structural changes of Nafion induced by water uptakes were characterized in terms of the density and the pore size distribution. It was found that membrane hydration leads to a growth of separated water domains, which are gradually interconnected via newly formed water channels. The sorption and diffusion of H2 and O2 were studied at different temperatures and water contents of Nafion. Simulation results show that the water loading reduces gas solubilities as the adsorption site of gas molecules transforms from small cavities to large surfaces due to the enlargement of aqueous domains. However, such an opening of Nafion porous nanostructure effectively reduces gas diffusion barriers, and results in a 2-fold increase of O2 diffusivities. Molecular configurations of gases inside Nafion nanoporous frameworks were examined on the basis of calculated radial distribution functions. DA - 2012/08/23 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4f99166f-4fca-4a1a-98e7-0d40ada8ffa5 ER - TY - JOUR TI - Effect of clathrate hydrate formation and decomposition on NMR parameters in THF–D2O Solution DO - 10.1021/jp303595y AU - Rousina-Webb, Alexander AU - Leek, Donald M. AU - Ripmeester, John T2 - The Journal of Physical Chemistry B SN - 1520-6106 SN - 1520-5207 VL - 116 IS - 25 SP - 7544 EP - 7547 AB - The NMR spin–lattice relaxation time (T1), spin–spin relaxation time (T2) and the diffusion coefficient D were measured for 1H in a 1:17 mol % solution of tetrahydrofuran (THF) in D2O. The aim of the work was to clarify some earlier points raised regarding the utility of these measurements to convey structural information on hydrate formation and reformation. A number of irregularities in T1 and T2 measurements during hydrate processes reported earlier are explained in terms of the presence of interfaces and possible temperature gradients. We observe that T1 and T2 in solution are exactly the same before and after hydrate formation, thus confirming that the solution is isotropic. This is inconsistent with the presence of memory effects, at least those that may affect the dynamics to which T1 and T2 are sensitive. The measurement of the diffusion coefficient for a number of hours in the subcooled solution before nucleation proved invariant with time, again suggesting that the solution remains isotropic without affecting the guest dynamics and diffusion. DA - 2012/06/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d27a8658-9dfc-4dd7-9774-47b9d36ef63d ER - TY - JOUR TI - Multinuclear solid-state nuclear magnetic resonance and density functional theory characterization of interaction tensors in taurine DO - 10.1021/jp210844t AU - O’Dell, Luke A. AU - Ratcliffe, Christopher I. AU - Kong, Xianqi AU - Wu, Gang T2 - The Journal of Physical Chemistry A SN - 1089-5639 SN - 1520-5215 VL - 116 IS - 3 SP - 1008 EP - 1014 AB - A variety of experimental solid-state nuclear magnetic resonance (NMR) techniques has been used to characterize each of the elements in 2-aminoethane sulfonic acid (taurine). A combination of 15N cross-polarization magic angle spinning (CPMAS), 14N ultrawideline, and 14N overtone experiments enabled a determination of the relative orientation of the nitrogen electric field gradient and chemical shift tensors. 17O spectra recorded from an isotopically enriched taurine sample at multiple magnetic fields allowed the three nonequivalent oxygen sites to be distinguished, and NMR parameters calculated from a neutron diffraction structure using density functional theory allowed the assignment of the 17O parameters to the correct crystallographic sites. This is the first time that a complete set of 17O NMR tensors are reported for a sulfonate group. In combination with 1H and 13C MAS spectra, as well as a previously reported 33S NMR study, this provides a very broad set of NMR data for this relatively simple organic molecule, making it a potentially useful structure on which to test DFT calculation methods (particularly for the quadrupolar nuclei 14N, 17O, and 33S) or NMR crystallography approaches. DA - 2012/01/26 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f10c8850-1ad3-4166-add0-fc686374fe0a ER - TY - JOUR TI - Molecular modeling of the dissociation of methane hydrate in contact with a silica surface DO - 10.1021/jp2086544 AU - Bagherzadeh, S. Alireza AU - Englezos, Peter AU - Alavi, Saman AU - Ripmeester, John A. T2 - The Journal of Physical Chemistry B SN - 1520-6106 SN - 1520-5207 VL - 116 IS - 10 SP - 3188 EP - 3197 AB - We use constant energy, constant volume (NVE) molecular dynamics simulations to study the dissociation of the fully occupied structure I methane hydrate in a confined geometry between two hydroxylated silica surfaces between 36 and 41 Å apart, at initial temperatures of 283, 293, and 303 K. Simulations of the two-phase hydrate/water system are performed in the presence of silica, with and without a 3 Å thick buffering water layer between the hydrate phase and silica surfaces. Faster decomposition is observed in the presence of silica, where the hydrate phase is prone to decomposition from four surfaces, as compared to only two sides in the case of the hydrate/water simulations. The existence of the water layer between the hydrate phase and the silica surface stabilizes the hydrate phase relative to the case where the hydrate is in direct contact with silica. Hydrates bound between the silica surfaces dissociate layer-by-layer in a shrinking core manner with a curved decomposition front which extends over a 5–8 Å thickness. Labeling water molecules shows that there is exchange of water molecules between the surrounding liquid and intact cages in the methane hydrate phase. In all cases, decomposition of the methane hydrate phase led to the formation of methane nanobubbles in the liquid water phase. DA - 2012/03/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d9b4b06a-037d-4284-b64b-96e065f70164 ER - TY - JOUR TI - Reactions of the cumyloxyl and benzyloxyl radicals with strong hydrogen bond acceptors. Large enhancements in hydrogen abstraction reactivity determined by substrate/radical hydrogen bonding DO - 10.1021/jo3019889 AU - Salamone, Michela AU - DiLabio, Gino A. AU - Bietti, Massimo T2 - The Journal of Organic Chemistry SN - 0022-3263 SN - 1520-6904 VL - 77 IS - 23 SP - 10479 EP - 10487 AB - A kinetic study on hydrogen abstraction from strong hydrogen bond acceptors such as DMSO, HMPA, and tributylphosphine oxide (TBPO) by the cumyloxyl (CumO•) and benzyloxyl (BnO•) radicals was carried out in acetonitrile. The reactions with CumO• were described in terms of a direct hydrogen abstraction mechanism, in line with the kinetic deuterium isotope effects, kH/kD, of 2.0 and 3.1 measured for reaction of this radical with DMSO/DMSO-d6 and HMPA/HMPA-d18. Very large increases in reactivity were observed on going from CumO• to BnO•, as evidenced by kH(BnO•)/kH(CumO•) ratios of 86, 4.8 × 10³, and 1.6 × 10^4 for the reactions with HMPA, TBPO, and DMSO, respectively. The kH/kD of 0.91 and 1.0 measured for the reactions of BnO• with DMSO/DMSO-d6 and HMPA/HMPA-d18, together with the kH(BnO•)/kH(CumO•) ratios, were explained on the basis of the formation of a hydrogen-bonded prereaction complex between the benzyloxyl α-C–H and the oxygen atom of the substrates followed by hydrogen abstraction. This is supported by theoretical calculations that show the formation of relatively strong prereaction complexes. These observations confirm that in alkoxyl radical reactions specific hydrogen bond interactions can dramatically influence the hydrogen abstraction reactivity, pointing toward the important role played by structural and electronic effects. DA - 2012/11/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bc3ea7ad-7038-4227-ab35-a1b804d6d81c ER - TY - JOUR TI - High-efficiency inverted solar cells based on a low bandgap polymer with excellent air stability DO - 10.1016/j.solmat.2011.09.042 AU - Chu, Ta-Ya AU - Tsang, Sai-Wing AU - Zhou, Jiayun AU - Verly, Pierre G. AU - Lu, Jianping AU - Beaupré, Serge AU - Leclerc, Mario AU - Tao, Ye T2 - Solar Energy Materials and Solar Cells SN - 09270248 VL - 96 SP - 155 EP - 159 KW - Inverted organic solar cells; Alternating dithienosilole and thienopyrrole-4,6-dione copolymer; ZnO nanocrystals; Processing additives; Air stability AB - A high-efficiency inverted bulk heterojunction (BHJ) solar cell with good air stability is fabricated using annealing-free ZnO nanocrystals as an electron-transport layer and a blend of a low bandgap polymer PDTSTPD and PC71BM as an active layer. A power conversion efficiency as high as 6.7% has been achieved on the inverted devices with an active area of 1.0 cm² using nitrobenzene as a processing additive. The device is highly stable, retaining 85% of its original efficiency after being stored in air for 32 days even without encapsulation. DA - 2012/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4303b135-80b5-4a58-9379-58cb179dc5cb ER - TY - JOUR TI - Community patterns of soil bacteria and nematodes in relation to geographic distance DO - 10.1016/j.soilbio.2011.10.006 AU - Monroy, Fernando AU - van der Putten, Wim H. AU - Yergeau, Étienne AU - Mortimer, Simon R. AU - Duyts, Henk AU - Bezemer, T. Martijn T2 - Soil Biology and Biochemistry SN - 00380717 VL - 45 SP - 1 EP - 7 KW - Geographic distance; Taxa turnover; Spatial distribution; PCR-DGGE; Grasslands; Microbial biogeography; Community similarity AB - Ecosystems consist of aboveground and belowground subsystems and the structure of their communities is known to change with distance. However, most of this knowledge originates from visible, aboveground components, whereas relatively little is known about how soil community structure varies with distance and if this variability depends on the group of organisms considered. In the present study, we analyzed 30 grasslands from three neighboring chalk hill ridges in southern UK to determine the effect of geographic distance (1–198 km) on the similarity of bacterial communities and of nematode communities in the soil. We found that for both groups, community similarity decayed with distance and that this spatial pattern was not related to changes either in plant community composition or soil chemistry. Site history may have contributed to the observed pattern in the case of nematodes, since the distance effect depended on the presence of different nematode taxa at one of the hill ridges. On the other hand, site-related differences in bacterial community composition alone could not explain the spatial turnover, suggesting that other factors, such as biotic gradients and local dispersal processes that we did not include in our analysis, may be involved in the observed pattern. We conclude that, independently of the variety of causal factors that may be involved, the decay in similarity with geographic distance is a characteristic feature of both communities of soil bacteria and nematodes. DA - 2012/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 614e99b9-f362-4566-857a-e228ce4d150c ER - TY - JOUR TI - Decoupling sensor morphology and material: atomic layer deposition onto nanocolumn scaffolds DO - 10.1016/j.snb.2011.08.024 AU - Taschuk, M. T. AU - Harris, K. D. AU - Smetaniuk, D. P. AU - Brett, M. J. T2 - Sensors and Actuators B: Chemical SN - 09254005 VL - 162 IS - 1 SP - 1 EP - 6 KW - Glancing angle deposition; Atomic layer deposition; TiO2; Si; SiO2; Relative humidity; Sensors AB - We have demonstrated direct surface modification of nanocolumn relative humidity sensors with conformal coatings deposited by atomic layer deposition (ALD). TiO2 and Si nanocolumn films were fabricated using glancing-angle deposition (GLAD). Both film types were subsequently coated with ≈0.3–4 nm thick ALD TiO2. The impact of the addition of subnanometer TiO2 layers on water contact angle, sensor responsivity, and the utility of an ultraviolet regeneration procedure has been tested. We have found that TiO2 coatings as thin as 0.5 nm provide much of the humidity sensing and regeneration functionality of a photocatalytic TiO2 film. In principle, any GLAD film architecture may be used as a scaffold for an active sensing layer, decoupling surface functionality and nanoscale morphology. Such capability offers an additional degree of freedom for designers of nanostructured gas sensors. DA - 2012/02/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 15267506-a848-4a09-9b0e-04961d0d197e ER - TY - JOUR TI - Thermal spray 2012 : proceedings from the international spray conference and exposition AU - Lima, R. S. AU - Agarwal, A. AU - Hyland, M. M. AU - Lau, Y.-C. AU - Li, C.-J. AU - McDonald, A. AU - Toma, F.-L. T3 - International Thermal Spray 2012 Conference and Exposition (ITSC 2012), 21-24 May 2012, Houston, Texas, USA AB - Complete proceedings, 156 papers, from ITSC 2012: Proceedings from the International Thermal Spray Conference and Exposition, May 21-24, 2012, Houston, Texas, USA. DA - 2012/05/24 PY - 2012 PB - ASM International UR - http://www.asminternational.org/portal/site/www/menuitem.2b9d1953d012ee1480a3c01026e110a0?vgnextoid=434d8ff08fc8c310VgnVCM100000621e010aRCRD&itemId=cp2012itscl#details LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 30a04053-be94-4e8e-9ef1-aa84eb9db229 ER - TY - JOUR TI - Poly(lactic acid) crystallization DO - 10.1016/j.progpolymsci.2012.07.005 AU - Saeidlou, Sajjad AU - Huneault, Michel A. AU - Li, Hongbo AU - Park, Chul B. T2 - Progress in Polymer Science SN - 00796700 VL - 37 IS - 12 SP - 1657 EP - 1677 KW - Poly(lactic acid); Polylactide; PLA; Crystallization; Kinetics; Review AB - Poly(lactic acid) is a biobased and compostable thermoplastic polyester that has rapidly evolved into a competitive commodity material over the last decade. One key bottleneck in extending the use of PLA is the control of its crystallinity. Understanding the crystallization behavior is particularly crucial to control PLA's degradation rate, thermal resistance as well as optical, mechanical and barrier properties. PLA crystallization has also been a particularly rich topic from a fundamental point of view because of the existence of the two enantiomeric forms of lactic acid that can be used to control the crystallization rate but also to form high melting point stereocomplex structures. This article presents an overview of the current understanding on the fundamentals of PLA crystallization in quiescent conditions and on the practical means to enhance its rate. Data from the abundant literature on PLA crystallization were compiled and analyzed to provide comprehensive relationships between crystallization kinetics and the main molecular structure characteristics of PLA. In addition, the most promising efforts in enhancing PLA crystallization kinetics through plasticization or heterogeneous nucleation were reviewed. DA - 2012/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4becb85f-44e8-4eb1-93a7-8a22784c6d8c ER - TY - JOUR TI - Degradation mechanism of benzodithiophene-based conjugated polymers when exposed to light in air DO - 10.1021/am300362b AU - Alem, Salima AU - Wakim, Salem AU - Lu, Jianping AU - Robertson, Gilles AU - Ding, Jianfu AU - Tao, Ye T2 - ACS Applied Materials & Interfaces SN - 1944-8244 SN - 1944-8252 VL - 4 IS - 6 SP - 2993 EP - 2998 KW - benzodithiophene; low band gap polymers; solar cell; bulk heterojunction; photostability AB - We report the investigation of the air photostability of benzo[1,2-b:4,5-b′]dithiophene (BDT) based conjugated polymers using UV–visible spectroscopy, X-ray photoelectron spectroscopy, gel permeation chromatography, and nuclear magnetic resonance spectroscopy. Three low band gap alternating D–A copolymers consisting of 3-fluoro-2-heptylcarbonylthieno[3,4-b]thiophene and alkyl-substituted BDT, alkoxy-substituted BDT, or dithienosilole, respectively, were prepared for investigating their photovoltaic performance and photostability. After only two hours of simultaneous exposure to light and air, the main absorption peak of the polymer films containing BDT units blue-shifted and its intensity dramatically decreased. We demonstrated that the BDT unit underwent dramatic structural change under illumination in air by reacting with the oxygen molecules at the excited state, leading to the disruption of the main-chain conjugation of the polymer. As a result, the color of the alkyl-BDT based polymer film permanently changed from deep blue to light yellow. In contrast, the dithienosilole based polymer was quite stable when treated under the same condition with negligible change in the absorption spectrum. DA - 2012/06/27 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 69dbfb5b-edb1-422c-a274-e32599eb8ea2 ER - TY - JOUR TI - Size reduction of CdSe/ZnS quantum dots by a peptidic amyloid supergelator DO - 10.1021/am3001715 AU - Zaman, Md. Badruz AU - Bardelang, David AU - Prakesch, Michaël AU - Leek, Donald M. AU - Naubron, Jean-Valère AU - Chan, Gordon AU - Wu, Xiaohua AU - Ripmeester, John A. AU - Ratcliffe, Christopher I. AU - Yu, Kui T2 - ACS Applied Materials and Interfaces SN - 1944-8244 SN - 1944-8252 VL - 4 IS - 3 SP - 1178 EP - 1181 KW - nanoparticles; etching; peptide; gelator; self-assembly; quantum dots AB - Anchoring of a self-assembling dipeptide on the surface of core/shell CdSe/ZnS quantum dots resulted in a competition between coordination of the surface atoms of the QDs and the strong tendency for the dipeptide to self-assemble in toluene. This resulted in a mild QD etching and in a corresponding increase in the band gap of the nanocrystals whose photoluminescent emission gradually turns blue with time. The FmocLeuLeuOH dipeptide supergelator self-assembles in fibrils in which the Fmoc groups are surrounded by the pendant isobutyl side chains of the leucine residues with vibrational circular dichroism (VCD) and liquid- and solid-state NMR attributes of twist anti-parallel β-sheets. DA - 2012/03/28 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e96b8fd6-1102-423f-b603-dfc82d3a0c8d ER - TY - JOUR TI - Large-Scale Production of PMMA/SWCNT Composites Based on SWCNT Modified with PMMA DO - 10.1021/am201824k AU - Fraser, Robin Anderson AU - Stoeffler, Karen AU - Ashrafi, Behnam AU - Zhang, Yunfa AU - Simard, Benoit T2 - ACS Applied Materials & Interfaces SN - 1944-8244 SN - 1944-8252 VL - 4 IS - 4 SP - 1990 EP - 1997 KW - single-walled carbon nanotubes (SWCNT); polymethyl methacrylate (PMMA); covalent functionalization; dispersion AB - In this work, a two-step method consisting of in situ polymerization of polymethyl methacrylate (PMMA) in the presence of single-walled carbon nanotubes (SWCNT), followed by the redispersion of the resulting compound in dimethylformamide (DMF), was used to fabricate SWCNT modified with PMMA (SWCNT–PMMA). Raman spectroscopy revealed that PMMA was merely wrapped around the SWCNT when raw SWCNT or purified SWCNT were used as the starting material. However, PMMA was covalently bonded to SWCNT when acid treated SWCNT (SWCNT-COOH) was used as the starting material. SWCNT–PMMA compounds were further diluted in pure PMMA by conventional melt compounding at large scale (several kilograms) to obtain transparent composites containing 0.09 wt % SWCNT. The micro- and nano-dispersion of the SWCNT in the composites were analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The thermal and mechanical properties of the composites were determined by thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), tensile testing, and Charpy impact testing. At the the low SWCNT loading studied, the tensile properties remain unchanged, whereas the impact strength improves by 20%. DA - 2012/04/25 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : eace6c8a-b940-4823-9e79-88b35717cdde ER - TY - JOUR TI - Capillary electrophoresis mass spectrometry for the characterization of O-acetylated N-glycans from fish serum DO - 10.1021/ac301889k AU - Jayo, Roxana G. AU - Li, Jianjun AU - Chen, David D. Y. T2 - Analytical Chemistry SN - 0003-2700 SN - 1520-6882 VL - 84 IS - 20 SP - 8756 EP - 8762 AB - O-Acetylated N-glycans from fish serum of Atlantic salmon (Salmo salar) are characterized by capillary electrophoresis (CE) in conjunction with both laser-induced fluorescence (LIF) and mass spectrometry (MS) detection methods. Glycans derivatized with negatively charged fluorescent label 8-aminopyrene-1,2,6-trisulfonate (APTS) were separated to obtain a CE-LIF profile of the complex glycan mixture, and the profile concurs with that obtained by using electrospray mass spectrometry. The identity of the APTS-labeled glycans was confirmed by CE–MS. The same glycans can be identified also in their native state by CE–MS without derivatization. The structural variations of O-acetylated sialic acid isomers in fish serum glycans are investigated by CE–MS/MS. Selected ion monitoring provided useful structural information of the underivatized glycans from fragmentation spectra. New complex fish serum glycans that are not reported previously were observed and characterized. These methods may be useful not only for the characterization of acetylation of complex glycans but also to study other types of glycan modifications, as well as to allow determination of overall glycan composition in glycoproteins. DA - 2012/10/16 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 581586a7-a076-4e6d-ae94-32cfa1f9264d ER - TY - JOUR TI - Protein quantitation using Ru-NHS ester tagging and isotope dilution high-pressure liquid chromatography–inductively coupled plasma mass spectrometry determination DO - 10.1021/ac203141d AU - Liu, Rui AU - Lv, Yi AU - Hou, Xiandeng AU - Yang, Lu AU - Mester, Zoltan T2 - Analytical Chemistry SN - 0003-2700 SN - 1520-6882 VL - 84 IS - 6 SP - 2769 EP - 2775 AB - An accurate, simple, and sensitive method for the direct determination of proteins by nonspecies specific isotope dilution and external calibration high-performance liquid chromatography–inductively coupled plasma mass spectrometry (HPLC–ICPMS) is described. The labeling of myoglobin (17 kDa), transferrin (77 kDa), and thyroglobulin (670 kDa) proteins was accomplished in a single-step reaction with a commercially available bis(2,2′-bipyridine)-4′-methyl-4-carboxybipyridine-ruthenium N-succinimidyl ester-bis(hexafluorophosphate) (Ru-NHS ester). Using excess amounts of Ru-NHS ester compared to the protein concentration at optimized labeling conditions, constant ratios for Ru to proteins were obtained. Bioconjugate solutions containing both labeled and unlabeled proteins as well as excess Ru-NHS ester reagent were injected onto a size exclusion HPLC column for separation and ICPMS detection without any further treatment. A 99Ru enriched spike was used for nonspecies specific ID calibration. The accuracy of the method was confirmed at various concentration levels. An average recovery of 100% ± 3% (1 standard deviation (SD), n = 9) was obtained with a typical precision of better than 5% RSD at 100 μg mL–1 for nonspecies specific ID. Detection limits (3SD) of 1.6, 3.2, and 7.0 fmol estimated from three procedure blanks were obtained for myoglobin, transferrin, and thyroglobulin, respectively. These detection limits are suitable for the direct determination of intact proteins at trace levels. For simplicity, external calibration was also tested. Good linear correlation coefficients, 0.9901, 0.9921, and 0.9980 for myoglobin, transferrin, and thyroglobulin, respectively, were obtained. The measured concentrations of proteins in a solution were in good agreement with their volumetrically prepared values. To the best of our knowledge, this is the first application of nonspecies specific ID for the accurate and direct determination of proteins using a Ru-NHS ester labeling reagent. DA - 2012/03/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 90dde31b-2b63-4cfa-b93e-44370015e196 ER - TY - JOUR TI - Nonlinear signal response in electrospray mass spectrometry: implications for quantitation of arsenobetaine using stable isotope labeling by liquid chromatography and electrospray orbitrap mass spectrometry DO - 10.1021/ac203137n AU - Ouerdane, Laurent AU - Meija, Juris AU - Bakirdere, Sezgin AU - Yang, Lu AU - Mester, Zoltán T2 - Analytical Chemistry SN - 0003-2700 SN - 1520-6882 VL - 84 IS - 9 SP - 3958 EP - 3964 AB - Isotope amount ratio measurements by electrospray ionization mass spectrometry show large systematic biases. Moreover, the signal ratio response can vary nonlinearly with respect to the amount ratio depending on the concentration of the analyte or coeluting matrix components, among other things. Since isotope dilution relies inherently on the linearity of response, accurate quantitation is then more difficult to achieve. In this study, we outline a method to eliminate the quantitation errors due to the effects of the nonlinear signal response. The proposed approach is a hybrid of the method of standard additions and isotope dilution allowing correction for nonlinear trend. As a proof of concept, determination of arsenobetaine content in fish tissue was performed using liquid chromatography coupled with a linear quadrupole ion trap (LTQ) Orbitrap mass spectrometer. The nonlinear isotope dilution method could, in principle, be applied to correct isotope ratio measurement biases in popular relative quantitation methods of biomolecules such as stable isotope labeling by amino acids in cell culture (SILAC), isotope-coded affinity tag (ICAT), or isobaric tags for relative and absolute quantification (iTRAQ). DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6169a751-e6d1-4fa3-82ba-bf8ad787b88f ER - TY - JOUR TI - Porous graphitized carbon monolith as an electrode material for probing direct bioelectrochemistry and selective detection of hydrogen peroxide DO - 10.1021/ac203061m AU - He, Xiaoyun AU - Zhou, Lin AU - Nesterenko, Ekaterina P. AU - Nesterenko, Pavel N. AU - Paull, Brett AU - Omamogho, Jesse O. AU - Glennon, Jeremy D. AU - Luong, John H. T. T2 - Analytical Chemistry SN - 0003-2700 SN - 1520-6882 VL - 84 IS - 5 SP - 2351 EP - 2357 AB - For the first time, graphitized carbon particles with a high surface area have been prepared and evaluated as a new material for probing direct electrochemistry of hemoglobin (Hb). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) imaging revealed that the carbon monolithic skeleton was constructed by a series of mesopores with irregular shapes and an average pore diameter of 5.6 nm. With a surface area of 239.6 m2/g, carbon particles exhibited three major Raman peaks as commonly observed for carbon nanotubes and other carbon materials, i.e., the sp3 and sp2 carbon phases coexisted in the sample. A glassy carbon electrode modified with carbon monoliths and didodecyldimethylammonium bromide exhibited direct electron transfer between Hb molecules and the underlying electrode with a transfer rate constant of 6.87 s–1. The enzyme electrode displayed a pair of quasi-reversible reduction–oxidation peaks at −0.128 and −0.180 V, reflecting the well-known feature of the heme [Fe3+/Fe2+] redox couple: a surface-controlled electrochemical process with one electron transfer. This reagentless biosensing approach was capable of detecting H2O2, a simple molecule but plays an important role in analytical and biological chemistry, as low as 0.1 μM with linearity of 0.1–60 μM and a response time of <0.8 s, comparing favorably with other carbon based electrodes (5 s). DA - 2012/03/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ec367255-8b20-4d69-9846-60e5a3a5656c ER - TY - JOUR TI - Negative chemical ionization GC/MS determination of nitrite and nitrate in seawater using exact matching double spike isotope dilution and derivatization with triethyloxonium tetrafluoroborate DO - 10.1021/ac2030128 AU - Pagliano, Enea AU - Meija, Juris AU - Sturgeon, Ralph E. AU - Mester, Zoltan AU - D’Ulivo, Alessandro T2 - Analytical Chemistry SN - 0003-2700 SN - 1520-6882 VL - 84 IS - 5 SP - 2592 EP - 2596 AB - The alkylation of nitrite and nitrate by triethyloxonium tetrafluoroborate allows determination of their ethyl esters by headspace GC–MS. In the present study, significant improvement in analytical performance are achieved by using negative chemical ionization (CI–). Detection limits are improved for at least an order of magnitude than those achieved using electron impact ionization (EI). The derivatization procedure has been optimized and alkaline conditions are adopted to minimize the conversion of nitrite to nitrate (determined to be 0.07% at 100 mg/L NO2–) and to avoid the exchange of oxygen between the analytes and the solvent (water). Quantitation entails the use of isotopically enriched standards (N18O2– and 15NO3–), which also permits monitoring of potential conversion from nitrite to nitrate during the analysis (double spike isotope dilution). DA - 2012/03/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e12d8c8e-0d51-41e9-9fc6-e8d7d3d3731f ER - TY - JOUR TI - Determination of the atomic weight of ²⁸Si-enriched silicon for a revised estimate of the Avogadro Constant DO - 10.1021/ac203006j AU - Yang, Lu AU - Mester, Zoltán AU - Sturgeon, Ralph E. AU - Meija, Juris T2 - Analytical Chemistry SN - 0003-2700 SN - 1520-6882 VL - 84 IS - 5 SP - 2321 EP - 2327 AB - The much anticipated overhaul of the International System of Units (SI) will result in new definitions of base units in terms of fundamental constants. However, redefinition of the kilogram in terms of the Planck constant (h) cannot proceed without consistency between the Avogadro and Planck constants, which are both related through the Rydberg constant. In this work, an independent assessment of the atomic weight of silicon in a highly enriched ²⁸Si crystal supplied by the International Avogadro Coordination (IAC) was performed. This recent analytical approach, based on dissolution with NaOH and its isotopic characterization by multicollector inductively coupled plasma mass spectrometry, is critically evaluated. The resultant atomic weight Ar(Si) = 27.976 968 39(24)k=1 differs significantly from the most recent value of Ar(Si) = 27.976 970 27(23)k=1. Using the results generated herein for Ar(Si) along with other IAC measurement results for mass, volume, and the lattice spacing, the estimate of the Avogadro constant becomes NA = 6.022 140 40(19) × 10²³ mol⁻¹. DA - 2012/03/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6cb46257-105f-484c-862a-b13cfae80f33 ER - TY - JOUR TI - Star-forming substructure within molecular clouds DO - 10.1017/S1743921313000185 AU - Di Francesco, James T2 - Molecular Gas, Dust, and Star Formation in Galaxies T2 - Proceedings of the International Astronomical Union; 8 T3 - IAUS 292: Molecular Gas, Dust, and Star Formation in Galaxies, August 20-24, 2012, Beijing, China SN - 1743-9213 SN - 1743-9221 SP - 29 EP - 34 KW - ISM: dust; extinction — ISM: structure — ISM: evolution — submillimeter AB - Wide-field far-infrared/submillimeter continuum maps of molecular clouds by the Herschel Space Observatory GBS and HOBYS surveys are revealing the star-forming substructures that lead to star formation in dense gas. In particular, these maps have revealed the central role in clouds of filaments, likely formed through turbulent motions. These filaments appear to be non-isothermal and fragment into cores only when their column densities exceed a stability threshold. Organizations of filament networks suggest the relative role of turbulence and gravity can be traced in different parts of a cloud, and filament intersections may lead to larger amounts of mass flow that form the precursors of high-mass stars or clusters. DA - 2012/08 PY - 2012 PB - Cambridge University Press PB - International Astronomical Union PB - Union Astronomique Internationale LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d531d6d1-501f-46c6-9417-18f9faffbd30 ER - TY - JOUR TI - Neglected infectious diseases in Aboriginal communities: Haemophilus influenzae serotype a and Helicobacter pylori DO - 10.1016/j.vaccine.2012.09.063 AU - Ulanova, Marina AU - Tsang, Raymond AU - Altman, Eleonora T2 - Vaccine T3 - Neglected Infectious Diseases in Aboriginal Communities workshop, October 2011, Thunder Bay, Canada SN - 0264410X VL - 30 IS - 49 SP - 6960 EP - 6966 KW - Infectious diseases; Haemophilus influenzae serotype a (Hia); Helicobacter pylori; Vaccine development; Aboriginal communities AB - This report describes proceedings of a workshop entitled “Neglected Infectious Diseases in Aboriginal Communities” which took place in Thunder Bay, Ontario, Canada, on October 12, 2011. This workshop was jointly organized by the National Research Council of Canada (NRC), the National Microbiology Laboratory (Public Health Agency of Canada) and Northern Ontario School of Medicine (NOSM) with participants from the Medical Sciences Division and Clinical Sciences Division of NOSM, NRC, National Microbiology Laboratory (NML), Public Health Laboratory (Thunder Bay), Thunder Bay District Health Unit, and Regional Health Survey at Chiefs of Ontario. The main purpose of the workshop was to summarize the current state of knowledge on two less publicized infectious disease agents afflicting Canadian Aboriginal communities: Haemophilus influenzae serotype a (Hia) and Helicobacter pylori. Another highlight of this workshop was the discussion on novel approaches for vaccination strategies in the control and prevention of such disease agents. In conclusion, a long-term collaborative research framework was established between NRC, NML and NOSM to develop carbohydrate-based vaccines against these pathogens that may benefit the health of Canadian Aboriginal peoples and other population groups at risk. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0d20feb8-1419-46c2-ac55-c009677c50af ER - TY - JOUR TI - The SCAR astronomy & astrophysics from Antarctica scientific research programme DO - 10.1017/S1743921312017000 AU - Storey, John W. V. AU - Abe, Lyu AU - Andersen, Michael AU - Anderson, Philip AU - Burton, Michael AU - Cui, Xiangqun AU - Ichikawa, Takashi AU - Karle, Albrecht AU - Lloyd, James AU - Masi, Silvia AU - Steinbring, Eric AU - Travouillon, Tony AU - Tuthill, Peter AU - Zhou, Hongyang T2 - Astrophysics from Antarctica T2 - Proceedings of the International Astronomical Union; 8 T3 - Astrophysics from Antarctica (S288), August, 2012, Beijing, China SN - 1743-9213 SN - 1743-9221 SP - 275 EP - 295 KW - Telescopes; Atmospheric Effects; Instrumentation; Site Testing; Antarctica AB - SCAR, the Scientific Committee on Antarctic Research, is, like the IAU, a committee of ICSU, the International Council for Science. For over 30 years, SCAR has provided scientific advice to the Antarctic Treaty System and made numerous recommendations on a variety of matters. In 2010, Astronomy and Astrophysics from Antarctica was recognized as one of SCAR's five Scientific Research Programs. Broadly stated, the objectives of Astronomy & Astrophysics from Antarctica are to coordinate astronomical activities in Antarctica in a way that ensures the best possible outcomes from international investment in Antarctic astronomy, and maximizes the opportunities for productive interaction with other disciplines. There are four Working Groups, dealing with site testing, Arctic astronomy, science goals, and major new facilities. Membership of the Working Groups is open to any professional working in astronomy or a related field. DA - 2012/08 PY - 2012 PB - Cambridge University Press PB - International Astronomical Union PB - Union Astronomique Internationale LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ad3de12d-210d-4841-a3e5-c14316738460 ER - TY - JOUR TI - 225 GHz atmospheric opacity measurements from two Arctic sites DO - 10.1017/S1743921312016882 AU - Matsushita, S. AU - Chen, Ming-tang AU - Martin-Cocher, P. AU - Asada, K. AU - Chen, C.-P. AU - Inoue, M. AU - Paine, S. AU - Turner, D. AU - Steinbring, E. T2 - Astrophysics from Antarctica T2 - Proceedings of the International Astronomical Union; no. 8, issue S288 T3 - International Astronomical Union Symposium 288: Astrophysics from Antarctica, August 2012, Beijing, China SN - 1743-9213 SN - 1743-9221 SP - 204 EP - 207 KW - Arctic sites; 225 GHz opacity; site testing AB - We report the latest results of 225 GHz atmospheric opacity measurements from two Arctic sites; one on high coastal terrain near the Eureka weather station, on Ellesmere Island, Canada, and the other at the Summit Station near the peak of the Greenland icecap. This is a campaign to search for a site to deploy a new telescope for submillimeter Very Long Baseline Interferometry and THz astronomy in the northern hemisphere. Since 2011, we have obtained 3 months of winter data near Eureka, and about one year of data at Summit Station. The results indicate that these sites offer a highly transparent atmosphere for observations in submillimeter wavelengths. Summit Station is particularly excellent, and its zenith opacity at 225 GHz is statistically similar to the Atacama Large Milllimeter/submillimeter Array site in Chile. In winter, the opacity at Summit Station is even comparable to that observed at the South Pole. DA - 2012/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7b671455-1bad-4f24-a913-423480df3c92 ER - TY - JOUR TI - Disassembling glancing angle deposited films for high-throughput, single-post growth scaling measurements DO - 10.1017/S1431927612001080 AU - Siewert, Joshua Morgan Arthur AU - Laforge, Joshua Michael AU - Taschuk, Michael Thomas AU - Brett, Michael Julian T2 - Microscopy and Microanalysis SN - 1431-9276 SN - 1435-8115 VL - 18 IS - 05 SP - 1135 EP - 1142 KW - GLAD; growth; broadening; disassembling; isolating; scaling; single post AB - With growing interest in nanostructured thin films produced by glancing angle deposition (GLAD), it becomes increasingly important to understand their overall growth mechanics and nanocolumn structure. We present a new method of isolating the individual nanocolumns of GLAD films, facilitating automated measurement of their broadening profiles. Data collected for α = 81° TiO2 vertical nanocolumns deposited across a range of substrate rotation rates demonstrates that these rates influence growth scaling parameters. Further, individual posts were found in each case that violate predicted Kardar-Parisi-Zhang growth scaling limits. The technique's current iteration is comparable to existing techniques in speed: though data were studied from 10,756 individual objects, the majority could not be confidently used in subsequent analysis. Further refinement may allow high-throughput automated film characterization and permit close examination of subtle growth trends, potentially enhancing control over GLAD film broadening and morphology. DA - 2012/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0a1627c9-1fb4-4df0-929c-02b02de18fa1 ER - TY - JOUR TI - Evidence of a dual network/spherulitic crystalline morphology in PLA stereocomplexes DO - 10.1016/j.polymer.2012.10.030 AU - Saeidlou, Sajjad AU - Huneault, Michel A. AU - Li, Hongbo AU - Sammut, Pierre AU - Park, Chul B. T2 - Polymer SN - 00323861 VL - 53 IS - 25 SP - 5816 EP - 5824 KW - PLA; Stereocomplex; Crystallization AB - Stereocomplex formation between poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) in the melt state was investigated. Blends with up to 5% PDLA were prepared via melt-blending and characterized by rheological, calorimetric, X-ray diffraction (XRD) and optical microscopy techniques. Kinetic studies suggest that the stereocomplex formation half-time (t1/2) is in the range of 5–7 min. The nucleating role of the stereocomplex for PLA homocrystallization was demonstrated in XRD experiment and in optical microscopy observations through an increase in the spherulite density as well as the growth of a transcrystalline layer on stereocomplex spherulites. More interestingly, a dual crystalline morphology for PLA stereocomplex comprising a spherulitic and a network structure was revealed by optical microscopy observations. This complex morphology was associated to a double stereocomplex melting peak behavior observed after isothermal crystallization in DSC as well as to a huge viscosity increase observed in the presence of a small concentration of stereocomplex in a PLLA melt. DA - 2012/11/30 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 250a738e-67e9-4aef-a979-c6752b3a2419 ER - TY - JOUR TI - Characterization of nanometer-scale porosity in reservoir carbonate rock by focused ion beam–scanning electron microscopy DO - 10.1017/S1431927611012505 AU - Bera, Bijoyendra AU - Gunda, Naga Siva Kumar AU - Mitra, Sushanta K. AU - Vick, Douglas T2 - Microscopy and Microanalysis SN - 1431-9276 SN - 1435-8115 VL - 18 IS - 01 SP - 171 EP - 178 KW - reservoir rock; carbonate; dolomite core; FIB-SEM; serial sectioning; microstructure AB - Sedimentary carbonate rocks are one of the principal porous structures in natural reservoirs of hydrocarbons such as crude oil and natural gas. Efficient hydrocarbon recovery requires an understanding of the carbonate pore structure, but the nature of sedimentary carbonate rock formation and the toughness of the material make proper analysis difficult. In this study, a novel preparation method was used on a dolomitic carbonate sample, and selected regions were then serially sectioned and imaged by focused ion beam–scanning electron microscopy. The resulting series of images were used to construct detailed three-dimensional representations of the microscopic pore spaces and analyze them quantitatively. We show for the first time the presence of nanometer-scale pores (50–300 nm) inside the solid dolomite matrix. We also show the degree of connectivity of these pores with micron-scale pores (2–5 μm) that were observed to further link with bulk pores outside the matrix. DA - 2012/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 706ebe7e-4eeb-451f-b919-f27550e4b166 ER - TY - JOUR TI - Prolonged survival and serial magnetic resonance imaging/magnetic resonance spectroscopy changes in infantile Krabbe disease DO - 10.1016/j.pediatrneurol.2012.06.015 AU - Udow, Sean AU - Bunge, Martin AU - Ryner, Lawrence AU - Mhanni, Aizeddin A. AU - Salman, Michael S. T2 - Pediatric Neurology SN - 08878994 VL - 47 IS - 4 SP - 299 EP - 302 AB - Krabbe disease may present during infancy, late infancy, or adulthood. Earlier-onset disease is associated with shorter survival times. We present a case of infantile onset Krabbe disease with prolonged survival, initial intracranial optic nerves and optic chiasm hypertrophy, and serial changes on cranial magnetic resonance imaging and magnetic resonance spectroscopy. DA - 2012/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ed355650-df13-4b9f-8684-4cbbc03977b2 ER - TY - JOUR TI - Hole transfer from PbS nanocrystal quantum dots to polymers and efficient hybrid solar cells utilizing infrared photons DO - 10.1016/j.orgel.2012.08.009 AU - Zhang, Yanguang AU - Li, Zhao AU - Ouyang, Jianying AU - Tsang, Sai-Wing AU - Lu, Jianping AU - Yu, Kui AU - Ding, Jianfu AU - Tao, Ye T2 - Organic Electronics SN - 15661199 VL - 13 IS - 12 SP - 2773 EP - 2780 KW - Conjugated polymers; PbS nanocrystals; Solar cells; Heterojunction; Charge transfer; Infrared photovoltaics AB - Polymer/inorganic-nanocrystals bulk heterojunction solar cells, where inorganic semiconductor nanocrystals such as CdSe, CdS, CdTe, ZnO, TiO2, and silicon, replace the fullerene molecules as the electron acceptors, typically exhibit a power conversion efficiency (PCE) below 3% even after tremendous engineering efforts to optimize the nanocrystal size, shape, and nanoscale morphology. One promising feature of polymer hybrid solar cells is the ability to sensitize conjugated polymers, which on their own absorb only in the visible part of solar spectrum, into the infrared spectral range using infrared-active lead salt nanocrystal quantum dots (NQDs). Here we observed for the first time hole transfer from PbS NQDs to polymers as evidenced by the quenching of the PbS photoluminescence (PL), a sign of the presence of charge separating type II heterojunction. The type II band-offset at the NQD/polymer heterojunction enables efficient hole extraction from NQDs and leads to a record PCE of 3.80%, realized in a planar junction configuration under simulated air mass 1.5 global (AM 1.5G) irradiation of 100 mW/cm2. The photocurrent has an extended spectral range spanning from the ultraviolet (UV) to the infrared (IR). Contributions from the polymer and PbS to the photocurrent were identified. Infrared photons (>700 nm) contribute about 30% of the photocurrent and yield a high external quantum efficiency (EQE) of 20% at 1050 nm. DA - 2012/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 147bf7be-3061-4545-bc6c-4fcfcf1a6ec0 ER - TY - JOUR TI - Development of a turbojet engine gearbox test rig for prognostics and health management DO - 10.1016/j.ymssp.2012.05.013 AU - Rezaei, Aida AU - Dadouche, Azzedine T2 - Mechanical Systems and Signal Processing SN - 08883270 VL - 33 SP - 299 EP - 311 KW - Accessory gearbox; Defect to failure tests; Signal processing; Prognostics and health management; Vibration; Acoustics AB - Aircraft engine gearboxes represent one of the many critical systems/elements that require special attention for longer and safer operation. Reactive maintenance strategies are unsuitable as they usually imply higher repair costs when compared to condition based maintenance. This paper discusses the main prognostics and health management (PHM) approaches, describes a newly designed gearbox experimental facility and analyses preliminary data for gear prognosis. The test rig is designed to provide full capabilities of performing controlled experiments suitable for developing a reliable diagnostic and prognostic system. The rig is based on the accessory gearbox of the GE J85 turbojet engine, which has been slightly modified and reconfigured to replicate real operating conditions such as speeds and loads. Defect to failure tests (DTFT) have been run to evaluate the performance of the rig as well as to assess prognostic metrics extracted from sensors installed on the gearbox casing (vibration and acoustic). The paper also details the main components of the rig and describes the various challenges encountered. Successful DTFT results were obtained during an idle engine performance test and prognostic metrics associated with the sensor suite were evaluated and discussed. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 138f1ddf-6682-4c9a-87f7-46105c1ed499 ER - TY - JOUR TI - Inverted photovoltaic cells of nanocolumnar C60 filled with solution processed small molecule 3-Q DO - 10.1016/j.orgel.2012.07.039 AU - Thomas, M. AU - Li, W. AU - Bo, Z. S. AU - Brett, M. J. T2 - Organic Electronics SN - 15661199 VL - 13 IS - 11 SP - 2647 EP - 2652 KW - Glancing angle deposition; Small molecule thin films; Organic solar cells; C60 fullerene; Nanostructure; Inverted architecture AB - Nanocolumnar C60 films for inverted organic photovoltaic cells (OPVs) were fabricated by glancing angle deposition (GLAD), and morphologies depending on variation in deposition angle were studied. To complete the OPV devices, small molecules of the donor material 3-Q were spin coated into the C60 films. In order to avoid the difficulties of solvent stability of the C60 films, acetone was used as the process solvent for spin coating. The nanocolumnar morphology improves exciton harvesting by increasing absorbance while providing an effective conductive path for charge carriers. The resulting GLAD C60/3-Q devices outperformed both planar devices and PC61BM:3-Q bulk heterojunctions with threefold and twofold short-circuit current increases, respectively. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : dd22163b-c407-4520-9082-9f4cbb6f74aa ER - TY - JOUR TI - The use of laser range finder on a robotic platform for pipe inspection DO - 10.1016/j.ymssp.2012.03.006 AU - Liu, Zheng AU - Krys, Dennis T2 - Mechanical Systems and Signal Processing SN - 08883270 VL - 31 SP - 246 EP - 257 KW - Laser range finder; Underwater vehicle; Nondestructive inspection; Water pipe AB - In this paper, we investigate the use of a laser range finder on a robotic platform for buried water pipe inspection. A robotic platform carrying and manipulating multiple nondestructive inspection sensors may require accurately locating robot's body in the pipe. The laser range finder provides an accurate distance measurement, which can generate a profile of the pipe inner surface. This profile, on one hand, can be used to identify the location of the laser source and thus the robot's body. Such information can further help the navigation of the robot. On the other hand, the anomalies presented in the profile can be detected and characterized in terms of the range measurement. The simulated and real data tests presented in this paper demonstrate the feasibility and effectiveness of incorporating the laser range finder into a robotic platform for the underground pipe inspection. DA - 2012/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 80c264f8-2d18-4b35-bf13-f7098c130236 ER - TY - JOUR TI - Control of the active layer nanomorphology by using co-additives towards high-performance bulk heterojunction solar cells DO - 10.1016/j.orgel.2012.05.001 AU - Aïch, Badrou Réda AU - Lu, Jianping AU - Beaupré, Serge AU - Leclerc, Mario AU - Tao, Ye T2 - Organic Electronics SN - 15661199 VL - 13 IS - 9 SP - 1736 EP - 1741 KW - Conjugated polymers; Co-additives; Solar cells; Bulk heterojunction; Nanomorphology; PCBM AB - In this work, two high boiling-point solvents (1-chloronaphthalene (CN) and 1,8-diiodooctane (DIO)) were utilized as co-additives in ortho-dichlorobenzene (ODCB) and chlorobenzene (CB) solutions to fine tune the donor and acceptor domains in the bulk heterojunction (BHJ) of poly(benzo[1,2-b:4,5-b′]dithiophene-alt-thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) and fullerene derivatives. A power conversion efficiency of 7.1% and a fill factor up to 70% were obtained for solar cells with active area of 1 cm2 when using [6,6]-phenyl C61-butyric acid methyl ester (PC60BM) as acceptor, suggesting that an optimized morphology was achieved. DA - 2012/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 20ff8e96-ea5b-492d-bc9e-62b30a1637b3 ER - TY - JOUR TI - Estimation of impact forces between small bodies in waves DO - 10.1016/j.oceaneng.2012.03.001 AU - Raman-Nair, W. AU - Chin, S. N. T2 - Ocean Engineering SN - 0029-8018 VL - 46 SP - 46 EP - 51 KW - Hertz contact; Plastic deformation; Small bodies; Waves AB - Impact forces between small bodies colliding in a regular wave are estimated using the contact theory of Hertz and an elastoplastic model due to Lankarani and Nikravesh (1994). To determine the relative impact speed, the equations of motion for the bodies on a surface wave are formulated in two dimensions using the methods of Kane and Levinson (1985) and solved numerically. It is assumed that the motion normal to the wave surface is small and can be neglected, i.e. the bodies move along the propagating wave profile. A Stokes second order wave is used and the wave forces are applied using Morison's equation for a body in accelerated flow. Wind loads are similarly modeled using drag coefficients. DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d7a4949f-80dd-4e23-87fe-4e30b1b466a6 ER - TY - JOUR TI - Effect of arginine vasopressin on the behavioral activity in the behavior despair depression rat model DO - 10.1016/j.npep.2012.03.003 AU - Yang, Jun AU - Pan, Yan-Juan AU - Yin, Zhi-Kui AU - Hai, Guang-Fan AU - Lu, Lu AU - Zhao, Ying AU - Wang, Da-Xin AU - Wang, Huan AU - Wang, Gen T2 - Neuropeptides SN - 01434179 VL - 46 IS - 3 SP - 141 EP - 149 KW - Arginine vasopressin; Depression; Behavior despair; V1 receptor; V2 receptor; Brain; Periphery AB - Arginine vasopressin (AVP), a nonapeptide posterior hormone of the pituitary, is mainly synthesized and secreted in the hypothalamic paraventricular nucleus (PVN) and supraoptic nucleus (SON). Large numbers of studies have reported that AVP plays a role in depression. The present study was to investigate by which level, brain or periphery, AVP affects the behavioral activity in the behavior despair depression rat model. The results showed that (1) either forced swimming or tail suspension significantly increased AVP concentration not only in the brain (PVN, SON, frontal of cortex, hippocampus, amygdala, lumber spinal cord) but also in the periphery (posterior pituitary and serum); (2) intraventricular injection (icv) of AVP decreased the animal immobility time, whereas V1 receptor antagonist d(CH2)5Tyr(Me)AVP (icv) increased the animal immobility time in a dose-dependent manner not only in FST but also in TST, but the V2 receptor antagonist d(CH2)5[D-Ile, Ile, Ala-NH9]AVP did not change the animal immobility time in FST or TST; (3) V1, not V2 receptor antagonist could inhibit the animal immobility time decrease induced by AVP (icv); (4) neither AVP nor its receptor antagonist (including V1 and V2 receptor antagonist) influenced the animal immobility time in both FST and TST. The data suggested that AVP in the brain rather than the periphery played a role in the behavior despair depression by V1, not V2 receptors, which behavior despair might have a positive feedback effect on central AVP and blood AVP might have a negative feedback on central AVP in the depressive process. DA - 2012/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 43e4b1a1-c2a0-4704-aa18-a1af42f32db5 ER - TY - JOUR TI - First demonstration of a Compton gamma imager based on silicon photomultipliers DO - 10.1016/j.nima.2012.03.019 AU - Saull, P. R. B. AU - Sinclair, L. E. AU - Seywerd, H. C. J. AU - Hanna, D. S. AU - Boyle, P. J. AU - Macleod, A. M. L. T2 - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment SN - 01689002 VL - 679 SP - 89 EP - 96 KW - SiPM; Silicon photomultiplier; Compton; Gamma; Imager AB - We are developing a rugged and person-transportable Compton gamma imager for use in security investigations of radioactive materials, and for radiological incident remediation. The imager is composed of layers of scintillator with light collection for the forward layers provided by silicon photomultipliers and for the rear layer by photomultiplier tubes. As a first step, we have developed a 1/5th-scale demonstration unit of the final imager. We present the imaging performance of this demonstration unit for 137Cs at angles of up to 30° off-axis. Results are also presented for 113Sn and 22Na. This represents the first demonstration of the use of silicon photomultipliers as an embedded component for light collection in a Compton gamma imager. DA - 2012/07/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 46c88a88-0b56-42da-a3b3-65a3fc2dfa94 ER - TY - JOUR TI - Spectroscopic and photometric study of the contact binary BO CVn DO - 10.1016/j.newast.2012.04.004 AU - Zola, S. AU - Nelson, R. H. AU - Şenavcı, H. V. AU - Szymanski, T. AU - Kuźmicz, A. AU - Winiarski, M. AU - Jableka, D. T2 - New Astronomy SN - 13841076 VL - 17 IS - 8 SP - 673 EP - 678 KW - Binaries; Eclipsing binaries; Close binaries – fundamental parameters AB - We present the results of the study of the contact binary system BO CVn. We have obtained physical parameters of the components based on combined analysis of new, multi-color light curves and spectroscopic mass ratio. This is the first time the latter has been determined for this object. We derived the contact configuration for the system with a very high filling factor of about 88%. We were able to reproduce the observed light curve, namely the flat bottom of the secondary minimum, only if a third light has been added into the list of free parameters. The resulting third light contribution is significant, about 20–24%, while the absolute parameters of components are: M1 = 1.16, M2 = 0.39, R1 = 1.62 and R2 = 1.00 (in solar units). The O-C diagram shows an upward parabola which, under the conservative mass transfer assumption, would correspond to a mass transfer rate of dM/dt = 6.3 × 10−8M⊙/yr, matter being transferred from the less massive component to the more massive one. No cyclic, short-period variations have been found in the O-C diagram (but longer-term variations remain a possibility). DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7919f59e-a0fb-443b-89a5-aab5bdde4e11 ER - TY - JOUR TI - Cocaine sensitization does not alter SP effects on locomotion or excitatory synaptic transmission in the NAc of rats DO - 10.1016/j.neuropharm.2011.09.008 AU - Kombian, Samuel B. AU - Ananthalakshmi, Kethireddy V. V. AU - Zidichouski, Jeffrey A. AU - Saleh, Tarek M. T2 - Neuropharmacology SN - 00283908 VL - 62 IS - 2 SP - 825 EP - 832 KW - Substance abuse; Cocaine; Substance P; Excitatory postsynaptic currents; Synaptic plasticity; Neuropeptides AB - Substance P (SP) and cocaine employ similar mechanisms to modify excitatory synaptic transmission in the nucleus accumbens (NAc), a region implicated in substance abuse. Here we explored, using NAc slices, whether SP effects on these synaptic responses were altered in rats that have been sensitized to cocaine and whether SP could mimic cocaine in triggering increased locomotion in sensitized rats. Intraperitoneal (IP) injection of naïve rats with cocaine (15 mg/kg) caused increased locomotion by 408.5 ± 85.9% (n = 5) which further increased by 733.1 ± 157.8% (n = 5) following a week of cocaine sensitization. A similar challenge with 10 mg/kg of SP after cocaine sensitization did not produce significant changes in locomotion (170.6 ± 61.0%; n = 4). In contrast to cocaine, IP injection of rats with SP or SP5–11 (10–100 mg/kg) with or without phosphoramidon did not elicit changes in locomotion. In electrophysiological studies, both cocaine and SP depressed evoked NMDA and non-NMDA receptor-mediated excitatory synaptic currents (EPSCs) in slices obtained from naïve rats. In slices derived from cocaine-sensitized rats, cocaine but not SP produced a more profound decrease in non-NMDA compared to NMDA responses. Similar to that in naïve rats, cocaine’s effect on the EPSCs in these sensitized rats occluded those of SP. Thus, although SP and cocaine may employ similar mechanisms to depress EPSCs in the NAc, IP injection of SP does not mimic cocaine-induced hyperlocomotion indicating that not all of cocaine’s effects are mimicked by SP. DA - 2012/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : adc1dff7-db22-4cb7-882a-00d87e5ed4be ER - TY - JOUR TI - Processing thermography images for pitting corrosion quantification on small diameter ductile iron pipe DO - 10.1016/j.ndteint.2012.01.003 AU - Liu, Zheng AU - Genest, Marc AU - Krys, Dennis T2 - NDT & E International SN - 09638695 VL - 47 SP - 105 EP - 115 KW - Thermography; Image feature extraction; Corrosion quantification; Pipe condition assessment AB - The condition of a metallic pipe is determined mainly by the extent to which it is corroded. Thus, the quantification of pitting corrosion in terms of metal loss is required for the understanding of pipe condition. There are different ways to quantify corrosion pit geometry. Direct methods measure the pit depth of pipe samples, which are sand/grit blasted to remove corrosion products, and are often adopted in laboratory. Indirect methods employ non-destructive inspection techniques to detect and quantify the corrosion without sandblasting, which is preferred for field test. In this study, the pulsed thermography is considered for fast quantification of pitting corrosion in a ductile iron pipe, which is sandblasted. The thermography testing generates a sequence of infrared images, which reflect the diffusion process of heat through pipe wall. This paper proposes a processing procedure to extract the corrosion information from the thermography images with phase congruency measurement and local binary fitting. The extracted feature is further related to the corrosion damage. Among all the features, the second principal component demonstrates a reasonably good linear relationship with metal loss of the pipe. The application potential is demonstrated by the experimental results. DA - 2012/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5626b1b6-5394-41ba-bbf7-bf0e180a9be8 ER - TY - JOUR TI - Lap shear strength and fatigue life of friction stir spot welded AZ31 magnesium and 5754 aluminum alloys DO - 10.1016/j.msea.2012.07.019 AU - Chowdhury, S. H. AU - Chen, D. L. AU - Bhole, S. D. AU - Cao, X. AU - Wanjara, P. T2 - Materials Science and Engineering: A SN - 0921-5093 VL - 556 SP - 500 EP - 509 KW - Magnesium alloy; Aluminum alloy; Friction stir spot welding; Microstructure; Lap shear strength; Fatigue properties AB - Lightweighting is today considered as one of the key strategies in reducing fuel consumption and anthropogenic greenhouse gas emissions. The structural applications of lightweight magnesium and aluminum alloys in the transportation industry inevitably involve welding and joining while guaranteeing the safety and reliability of motor vehicles. This study was aimed at evaluating lap shear strength and fatigue properties of friction stir spot welded (FSSWed) AZ31B-H24 Mg and 5754-O Al alloys in three combinations, i.e., similar Mg-to-Mg, Al-to-Al, and dissimilar Al-to-Mg joints. The Mg/Mg similar weld had a nugget-shaped stir zone (SZ) around the keyhole where fine recrytallized equiaxed grains were observed. While the hardness profile of the Mg/Mg similar weld exhibited a W-shaped appearance, the lower hardness values appeared in the TMAZ and HAZ of both Mg/Mg and Al/Al similar welds. In the Al/Mg dissimilar weld, a characteristic interfacial layer consisting of intermetallic compounds (IMC) Al12Mg17 and Al3Mg2 was observed. Both Mg/Mg and Al/Al similar welds had significantly higher lap shear strength, failure energy and fatigue life than the Al/Mg dissimilar weld. While the Al/Al weld displayed a slightly lower lap shear strength than the Mg/Mg weld, the Al/Al weld had higher failure energy and fatigue life. Three types of failure modes were observed. In the Mg/Mg and Al/Al similar welds, at higher cyclic loads nugget pullout failure occurred due to fatigue crack propagation circumferentially around the nugget, while at lower cyclic loads fatigue failure occurred perpendicular to the loading direction caused by the opening of keyhole through crack initiation in the TMAZ and HAZ. In the Al/Mg dissimilar weld nugget debonding failure mode was observed because of the presence of an interfacial IMC layer. DA - 2012/07/11 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fb101d2f-f8d1-4fe7-9273-9bed5c79f944 ER - TY - JOUR TI - Maximizing the integrity of linear friction welded Waspaloy DO - 10.1016/j.msea.2012.06.041 AU - Chamanfar, A. AU - Jahazi, M. AU - Gholipour, J. AU - Wanjara, P. AU - Yue, S. T2 - Materials Science and Engineering: A SN - 09215093 VL - 555 SP - 117 EP - 130 KW - Waspaloy; Linear friction welding; Weld integrity; Tensile properties; Microstructure AB - The Ni-base superalloy, Waspaloy, was linear friction welded (LFWed) under various processing parameters and then subjected to a post weld heat treatment (PWHT). Tensile testing integrated with the optical image correlation Aramis® system indicated that there is a critical axial shortening value (2 mm) below which LFWed and post weld heat treated (PWHTed) Waspaloy exhibited weak integrity. At and above this critical shortening, the yield strength and ultimate tensile stress (UTS) values were more or less the same as for the parent material. However, total elongation continued to increase with axial shortening even above the critical value due to decrease in width of thermo-mechanically affected zone (TMAZ). The sample with the highest axial shortening (4.9 mm) exhibited an elongation 91% of the parent material elongation. According to Aramis® data, the mixture rule can be used reliably to determine the contribution of TMAZ to the tensile elongation of PWHTed Waspaloy. Microstructure characterization across the weld in the as-LFWed and PWHTed conditions was carried out to correlate the process parameters and microstructural changes that affect the tensile properties. Weak integrity at axial shortening below 2 mm was mainly due to lack of bonding and/or presence of oxides at the weld interface. In the as-welded condition, a loss in hardness was observed, and related to the extensive dissolution of strengthening phase (γ′) in the weld area. The applied PWHT restored the hardness in the weld region. DA - 2012/10/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fe06c336-5b18-47dc-b83b-16d6f05275bf ER - TY - JOUR TI - Microstructure evolution and mechanical properties of dissimilar friction stir welded joints between AA1100-B4C MMC and AA6063 alloy DO - 10.1016/j.msea.2012.06.004 AU - Guo, J. AU - Gougeon, P. AU - Chen, X.-G. T2 - Materials Science and Engineering: A SN - 09215093 VL - 553 SP - 149 EP - 156 KW - Friction stir welding; Dissimilar joints; Al-B4C metal matrix composites; AA6063 alloy; Microstructure; Mechanical properties AB - The feasibility of dissimilar friction stir welding (FSW) between the AA1100-16 vol.% B4C metal matrix composite and the AA6063 alloy has been evaluated. The effect of the welding parameters on the interface bonding, joint microstructure and mechanical properties was investigated. The results revealed that all dissimilar joints produced under welding conditions investigated were stronger than the base materials of the Al-B4C composite. Analysis of the Mg concentration and the B4C particle distribution indicates that good material mixing and seamless bonding was achieved around the interface between the Al-B4C composite and the Al 6063 alloy during FSW. The electron backscatter diffraction analysis (EBSD) shows that during dissimilar FSW, there was a gradual microstructural evolution on both material sides, resulting in a variety of grain structures in the different weld zones. In the weld zones of FSW joints, the materials underwent dynamic recovery and recrystallization to different extents depending on their thermal mechanical history. The grain refinement of both materials in the nugget zone was observed. It is recommended that the 6063 aluminum alloy should be fixed on the advancing side and the use of an appropriate offset to the 6063 aluminum side is preferred. DA - 2012/09/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9f7e854b-bfb2-4068-87be-5ce6d23f91d5 ER - TY - JOUR TI - Short echo time in vivo prostate 1H-MRSI DO - 10.1016/j.mri.2011.09.020 AU - Venugopal, Niranjan AU - Mccurdy, Boyd AU - Al Mehairi, Salem AU - Alamri, Aziz AU - Sandhu, Gurdarshan S. AU - Sivalingam, Sri AU - Drachenberg, Darrel AU - Ryner, Lawrence T2 - Magnetic Resonance Imaging SN - 0730725X VL - 30 IS - 2 SP - 195 EP - 204 KW - Short TE; Conformal voxel; Magnetic resonance spectroscopic imaging; LCModel; Prostate cancer; Lipid contamination; Lipid suppression AB - Visualization of short echo time (TE) metabolites in prostate magnetic resonance spectroscopic imaging is difficult due to lipid contamination and pulse timing constraints. In this work, we present a modified pulse sequence to permit short echo time (TE=40ms) acquisitions with reduced lipid contamination for the detection of short TE metabolites. The modified pulse sequence employs the conformal voxel MRS (CV-MRS) technique, which automatically optimizes the placement of spatial saturation planes to adapt the excitation volume to the shape of the prostate, thus reducing lipid contamination in prostate magnetic resonance spectroscopic imaging (MRSI). Metabolites were measured and assessed using a modified version of LCModel for analysis of in vivo prostate spectra. We demonstrate the feasibility of acquiring high quality spectra at short TEs, and show the measurement of short TE metabolites, myo-inositol, scyllo-inositol, taurine and glutamine/glutamate for both single and multi-voxel acquisitions. In single voxels experiments, the reduction in TE resulted in 57% improvement in the signal-to-noise ratio (SNR). Additional 3D MRSI experiments comparing short (TE=40 ms), and long (TE=130 ms) TE acquisitions revealed a 35% improvement in the number of adequately fitted metabolite peaks (775 voxels over all subjects). This resulted in a 42±24% relative improvement in the number of voxels with detectable citrate that were well-fitted using LCmodel. In this study, we demonstrate that high quality prostate spectra can be obtained by reducing the TE to 40 ms to detect short T2 metabolites, while maintaining positive signal intensity of the spin-coupled citrate multiplet and managing lipid suppression. DA - 2012/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7d180c46-b634-43d9-8451-70b26b9e2dc6 ER - TY - JOUR TI - A volume microstrip RF coil for MRI microscopy DO - 10.1016/j.mri.2011.07.010 AU - Jasiński, Krzysztof AU - Młynarczyk, Anna AU - Latta, Peter AU - Volotovskyy, Vyacheslav AU - Węglarz, Władyslaw P. AU - Tomanek, Bogusław T2 - Magnetic Resonance Imaging SN - 0730725X VL - 30 IS - 1 SP - 70 EP - 77 KW - MRI microcoil; RF coil; Micro MRI; SNR; FEM AB - Quantitative magnetic resonance imaging (MRI) studies of small samples such as a single cell or cell clusters require application of radiofrequency (RF) coils that provide homogenous B1 field distribution and high signal-to-noise ratio (SNR). We present a novel design of an MRI RF volume microcoil based on a microstrip structure. The coil consists of two parallel microstrip elements conducting RF currents in the opposite directions, thus creating homogenous RF field within the space between the microstrips. The construction of the microcoil is simple, efficient and cost-effective. Theoretical calculations and finite element method simulations were used to optimize the coil geometry to achieve optimal B1 and SNR distributions within the sample and predict parameters of the coil. The theoretical calculations were confirmed with MR images of a 1-mm-diameter capillary and a plant obtained with the double microstrip RF microcoil at 11.7 T. The in-plane resolution of MR images was 24 μm×24 μm. DA - 2012/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 96a2d623-6fe1-4a93-9a9f-a0632bb6c922 ER - TY - JOUR TI - The role of WlaRG, WlaTB and WlaTC in lipooligosaccharide synthesis by Campylobacter jejuni strain 81116 DO - 10.1016/j.micpath.2012.03.004 AU - Holden, Karen M. AU - Gilbert, Michel AU - Coloe, Peter J. AU - Li, Jianjun AU - Fry, Benjamin N. T2 - Microbial Pathogenesis SN - 08824010 VL - 52 IS - 6 SP - 344 EP - 352 KW - Campylobacter jejuni; Lipooligosaccharide; Mutagenesis; Glycosyltransferase; Aminotransferase AB - Campylobacter jejuni is a major bacterial cause of gastroenteritis world-wide. C. jejuni produces a range of glycans including lipooligosaccharide (LOS), an important virulence factor. The genetic content of the LOS synthesis locus varies between C. jejuni strains and 19 classes have been described. Three LOS synthesis genes of C. jejuni strain 81116 (NCTC 11828), wlaRG, wlaTB and wlaTC were the focus of this study. WlaRG and the remaining two proteins of interest share sequence similarity to aminotransferases and glycosyltransferases, respectively. These genes were insertionally inactivated and phenotypically characterised. Each mutant produced truncated LOS. Mutants lacking WlaRG, WlaTB and WlaTC produced LOS with reduced immunogenicity. Both the wlaRG and wlaTC mutants were non-motile and aflagellate. In vitro invasion and adhesion assays revealed that the wlaRG, wlaTB and wlaTC mutants displayed reduced adherence to chicken embryo fibroblasts. All mutants were less invasive of human cells than 81116 confirming the role of intact LOS during invasion of human cells in vitro. Here we propose the general composition for the 81116 LOS core backbone based on capillary electrophoresis-mass spectrometry. DA - 2012/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6190837d-8563-46ea-9ce3-23ebb4d422e6 ER - TY - JOUR TI - Molecular simulation of CO2/N2 separation using vertically-aligned carbon nanotube membranes DO - 10.1016/j.memsci.2012.06.018 AU - Ban, Shuai AU - Huang, Cheng T2 - Journal of Membrane Science SN - 03767388 VL - 417-418 SP - 113 EP - 118 KW - Computer modeling; Molecular transport; Gas separation; Nanomaterials AB - The CO2/N2 permeation through carbon nanotube (CNT) membrane was studied using molecular simulations to explore its potential for flue gas separation. The theory of gas permeation was derived on the basis of the Maxwell–Stefan formulas. Adsorption isotherms calculated using grand-canonical Monte Carlo methods show a higher loading of pure CO2 than that of N2, while an approximately identical loading was found for CO2/N2 mixture with a feed pressure ratio of 1:9. The molecular snapshot indicates a concentrically layered structure inside the cylindrical channel of CNT. Results of molecular dynamics simulations show that the diffusion of N2 is a few times faster than that of CO2. For binary mixtures, the diffusion coefficients of CO2/N2 mixtures become identical at high concentrations due to the correlation effect that causes a slowing-down of the mobile species, and a speed-up of the other tardy component. The calculated N2 permeance agrees with the experimental measurement. The computed CO2 flux through CNT membranes is higher than N2 for single components, while they become nearly equal under flue gas conditions. DA - 2012/11/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4fbbfd81-8b9e-4781-930e-cd18e63abf11 ER - TY - JOUR TI - Biomechanically constrained groupwise ultrasound to CT registration of the lumbar spine DO - 10.1016/j.media.2010.07.008 AU - Gill, Sean AU - Abolmaesumi, Purang AU - Fichtinger, Gabor AU - Boisvert, Jonathan AU - Pichora, David AU - Borshneck, Dan AU - Mousavi, Parvin T2 - Medical Image Analysis SN - 13618415 VL - 16 IS - 3 SP - 662 EP - 674 KW - Ultrasound; Spine; Multimodal registration; Biomechanical model AB - We present a groupwise US to CT registration algorithm for guiding percutaneous spinal interventions. In addition, we introduce a comprehensive validation scheme that accounts for changes in the curvature of the spine between preoperative and intraoperative imaging. In our registration methodology, each vertebra in CT is treated as a sub-volume and transformed individually. A biomechanical model is used to constrain the displacement of the vertebrae relative to one another. The sub-volumes are then reconstructed into a single volume. During each iteration of registration, an US image is simulated from the reconstructed CT volume and an intensity-based similarity metric is calculated with the real US image. Validation studies are performed on CT and US images from a sheep cadaver, five patient-based phantoms designed to preserve realistic curvatures of the spine and a sixth patient-based phantom where the curvature of the spine is changed between preoperative and intraoperative imaging. For datasets where the spine curve between two imaging modalities was artificially perturbed, the proposed methodology was able to register initial misalignments of up to 20 mm with a success rate of 95%. For the phantom with a physical change in the curvature of the spine introduced between the US and CT datasets, the registration success rate was 98.5%. Finally, the registration success rate for the sheep cadaver with soft-tissue information was 87%. The results demonstrate that our algorithm allows for robust registration of US and CT datasets, regardless of a change in the patients pose between preoperative and intraoperative image acquisitions. DA - 2012/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1b0b6d6a-6968-400d-9e6a-f44bb21b3b57 ER - TY - JOUR TI - International comparison of quantum AC voltage standards for frequencies up to 100kHz DO - 10.1016/j.measurement.2012.03.008 AU - Filipski, Piotr S. AU - van den Brom, Helko E. AU - Houtzager, Ernest T2 - Measurement T3 - XVIII TC4 IMEKO Symposium and IX Semetro, September 2011, Natal, Brazil SN - 02632241 VL - 45 IS - 9 SP - 2218 EP - 2225 KW - Josephson arrays; Signal synthesis; Standards; AC voltage standard AB - This paper presents results of an international comparison of two quantum AC voltage standards based on pulse-driven Josephson arrays. The two systems differ in several hardware and software characteristics as well as in the level of automation, features which can influence the accuracy of transferring the quantum-standard voltage value to a calibrated instrument. The comparison was performed at 100 mV, 20 mV and 12 mV, at frequencies between 2.5 kHz and 100 kHz. An electronically-aided thermal transfer standard was used as a travelling standard. At the most accurate voltage and frequency point, 100 mV at 2.5 kHz, both laboratories agreed to better than 1 part in 10^6. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 64e2ba41-4b52-496f-8582-e61ef10a02eb ER - TY - JOUR TI - Discovery of Al2O3 particles incorporation mechanism in plasma electrolytic oxidation of AM60B magnesium alloy DO - 10.1016/j.matlet.2012.07.032 AU - Li, Xijin AU - Luan, Ben Li T2 - Materials Letters SN - 0167577X VL - 86 SP - 88 EP - 91 KW - Particle incorporation; Al2O3; Magnesium; Plasma electrolytic oxidation AB - Al2O3 particles were suspended in the aluminate electrolyte to form a ceramic coating on an AM60B magnesium alloy by plasma electrolytic oxidation (PEO), and a new mechanism for the Al2O3 particle incorporation in the coating was discovered. Energy Dispersive Spectroscopy (EDS) results showed that Al2O3 addition increased the Al content in the coating. The absence of Al2O3 particles combined with the increased MgAl2O4/MgO phase ratio in the coatings with the addition of Al2O3 indicated that the Al2O3 particles participated in chemical reactions during the coating formation, as opposed to a previously reported understanding of simple mechanical incorporation. DA - 2012/11/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : df949107-19fb-4a80-b630-0f32c9f875a1 ER - TY - JOUR TI - Suppressed liquation and microcracking in linear friction welded WASPALOY DO - 10.1016/j.matdes.2011.11.007 AU - Chamanfar, A. AU - Jahazi, M. AU - Gholipour, J. AU - Wanjara, P. AU - Yue, S. T2 - Materials & Design SN - 02613069 VL - 36 SP - 113 EP - 122 KW - Non-ferrous metals and alloys; Welding; Microstructure AB - Fusion welding of nickel-base superalloys is often associated with fusion zone solidification cracking and/or liquation induced heat affected zone (HAZ) cracking. As an alternative joining technology, linear friction welding (LFW) was used in the current study to join the nickel-base superalloy, WASPALOY. Under the experimental conditions used in the present investigation, the temperature data recorded by inserting thermocouples at different locations from the weld interface indicated that the temperature in the weld area reached up to 1280 °C, which is at least 50 °C below the melting point of the bulk alloy. However, this temperature is well above the liquation temperature of the low melting point components in the alloy (1245 °C). As a result, liquation may occur in linear friction welded (LFWed) WASPALOY. The occurrence of liquation and/or microcracking was investigated using optical microscopy (OM), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) X-ray mapping. The high pressure applied during the oscillation and forge phases of the LFW process and the resulting γ grain refinement contributed in preventing liquation and microcracking in the weldments. Furthermore, according to the SEM and X-ray mapping results, LFW altered the chemical composition, morphology and size of the γ′ precipitates at a location of 2 mm from the weld interface. It was determined that γ′ coalescence at 2 mm from the weld interface played a role in decreasing the microhardness (by 30%) relative to the base metal. DA - 2012/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d0111f36-02b6-4a9e-881c-a7dffa171a61 ER - TY - JOUR TI - The characteristics of gas hydrates recovered from Shenhu area in the South China Sea DO - 10.1016/j.margeo.2012.03.004 AU - Liu, Changling AU - Ye, Yuguang AU - Meng, Qingguo AU - He, Xingliang AU - Lu, Hailong AU - Zhang, Jian AU - Liu, Jian AU - Yang, Shengxiong T2 - Marine Geology SN - 00253227 VL - 307-310 SP - 22 EP - 27 KW - Gas hydrates; South China Sea; Methane; Occurrence; Hydration number; Gas composition AB - For the first time gas hydrate samples were recovered in the South China Sea during a drilling campaign implemented in Shenhu area in June 2007. Laboratory based studies for the characteristics of gas hydrate were carried out on two hydrate-bearing sediment samples. Observations found that gas hydrates occurred in the pores of fine grained sediments. The hydrates were structure I based on the Raman spectroscopic results. The guest gas molecules in hydrate cages were predominantly methane (> 99.3%) and trace amount of ethane (0.4%) and propane (0.04%) as determined with the method of gas chromatography. As estimated from the intensities of Raman peaks, the cage occupancy rates were more than 99% in large cage, and ~ 86% in small cage, respectively, corresponding to a hydration number of 5.9. DA - 2012/04/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 20edcb5f-24b1-4646-88e9-37b51abd553c ER - TY - JOUR TI - Wind-induced response and excitation characteristics of an inclined cable model in the critical Reynolds number range DO - 10.1016/j.jweia.2012.04.025 AU - Jakobsen, J. B. AU - Andersen, T. L. AU - Macdonald, J. H. G. AU - Nikitas, N. AU - Larose, G. L. AU - Savage, M. G. AU - McAuliffe, B. R. T2 - Journal of Wind Engineering and Industrial Aerodynamics SN - 01676105 VL - 110 SP - 100 EP - 112 KW - Bridge cable; Inclined circular cylinder; Surface pressures; Drag crisis; Critical Reynolds number; High reduced wind speed; Dry inclined cable galloping AB - This paper focuses on wind-induced vibrations of dry inclined bridge cables in the critical Reynolds number range. The cable response and the associated wind load characteristics are studied experimentally, in the third phase of a major wind tunnel investigation on cable aerodynamics at the National Research Council Canada. The displacement (and acceleration) response of a 6.7 m long section cable model, 160 mm in diameter, was monitored simultaneously with 162 surface pressure taps, for inclinations of 60°, 77° and 90°. The data corroborate the susceptibility of dry cables to respond, primarily in the across-flow direction, to load variations associated with transitions between flow regimes throughout the drag crisis region. The most vigorous vibrations (stopped at approximately 60% diameter response amplitude) were observed at 60°, with damping ratios below 0.2%. Significant “lock-in” between the lift force and the violent sway cable response was identified in terms of the transfer function between the two during the large vibration events. The large responses were confined to a narrow Reynolds number range, often at flow conditions giving the minimum normal (drag) coefficient and a significant derivative of the lift coefficient with respect to Reynolds number. Throughout the drag crisis region, significant variation in flow characteristics along the cable aligned at 60° has been observed, in terms of both mean pressure distributions and pressure fluctuations. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 32183bbe-60dc-4f0e-b661-9782955b8f58 ER - TY - JOUR TI - Shaping of bridge box girders to avoid vortex shedding response DO - 10.1016/j.jweia.2012.04.018 AU - Larsen, Allan AU - Wall, Alanna T2 - Journal of Wind Engineering and Industrial Aerodynamics T3 - 13th International Conference on Wind Engineering, July 10-15, 2011, Amsterdam, Netherlands SN - 0167-6105 VL - 104-106 IS - May-July SP - 159 EP - 165 KW - Vortex shedding excitation; Bridge decks; Section model tests AB - This paper presents a wind tunnel study carried out with the objective of exploring the effect of shape on vortex induced vibrations of trapezoidal box girder bridge decks. It is demonstrated that it is possible to derive a virtually vibration free deck and that the angle between the horizontal bottom plate and the inclined side panes is an important parameter in achieving this goal. DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : da1d45ba-f161-4c11-825d-c15231ade804 ER - TY - JOUR TI - Sectional model investigation at high Reynolds number for a super tall building DO - 10.1016/j.jweia.2012.03.028 AU - Larose, G. L. AU - Wall, A. AU - McAuliffe, B. R. AU - Kelly, D. AU - Stone, G. AU - Yakymyk, W. T2 - Journal of Wind Engineering and Industrial Aerodynamics T3 - 13th International Conference on Wind Engineering, July 10-15, 2011, Amsterdam, Netherlands SN - 01676105 VL - 104-106 IS - May-July SP - 49 EP - 55 KW - Super tall building; Vortex-shedding induced oscillations; Reynolds number; Sectional model; Wind tunnel tests AB - This paper presents the results of an experimental study of the influence of Reynolds number on the vortex-shedding excitation of a super tall building with a quasi-circular cross-section, uniform with height. Sectional model tests were carried out on a large model in a large wind tunnel at high wind speeds to reach Reynolds number in excess of 3 million based on the model diameter. Stationary model tests and free-to-respond model tests were carried out for various azimuth angles, in smooth and turbulent flow. The study revealed that for this building cross-section, the dynamic excitation due to vortex shedding was equally important at high Reynolds numbers when compared to experiments performed in the sub-critical Reynolds number regime. DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b497067d-d494-4add-987e-13e38a965515 ER - TY - JOUR TI - Reynolds-number and surface-modeling sensitivities for experimental simulation of flow over complex topography DO - 10.1016/j.jweia.2012.03.016 AU - McAuliffe, Brian R. AU - Larose, Guy L. T2 - Journal of Wind Engineering and Industrial Aerodynamics T3 - 13th International Conference on Wind Engineering, July 10-15, 2011, Amsterdam, Netherlands SN - 01676105 VL - 104-106 IS - May-July SP - 603 EP - 613 KW - Complex terrain; Wind farm; Atmospheric boundary layer; Wind profiles; Turbulence; Wind tunnel testing AB - This paper documents the development of an experimental approach for determining the wind characteristics over complex topography. Using fast-response pressure probes, vertical wind profiles were measured over wind-tunnel models representing the complex topography of a wind farm currently under construction. A terraced-model approach was taken to simplify the manufacturing of the topographic models, providing the added benefit of enhanced surface roughness from the terraced steps. A preliminary study in a small wind tunnel identified restrictions on the Reynolds number and terrace step size that are required for attaining adequate high-Reynolds-number boundary-layer characteristics at a scale of 1:1500. Subsequent measurements over the entire wind-farm topography were compared to site measurements from meteorological masts, from which recommendations for improved experimental simulation techniques are identified. DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 82d3d933-2d89-4c80-84f1-d7125dd8d0fd ER - TY - JOUR TI - Wind turbulence in speed skating: measurement, simulation and its effect on aerodynamic drag DO - 10.1016/j.jweia.2012.02.002 AU - D'auteuil, Annick AU - Larose, Guy L. AU - Zan, Steve J. T2 - Journal of Wind Engineering and Industrial Aerodynamics T3 - 13th International Conference on Wind Engineering, July 10-15, 2011, Amsterdam, Netherlands SN - 0167-6105 VL - 104-106 SP - 585 EP - 593 KW - Wind turbulence; Drag; Speed skater; Wind simulation; Wind tunnel AB - This paper presents the results of an investigation on the effect of wind turbulence for the reduction of drag for a speed skater. A speed skater competing in an indoor oval is subjected to turbulent flow conditions. Measurements of flow characteristics in a speed skating oval were made and a simulation of those conditions was developed in the NRC 2 m×3 m Wind Tunnel. Wind tunnel tests on mannequins of a speed skater with force measurement using an external balance have indicated that the reduction of drag coefficient with Reynolds number was strongly affected by the flow conditions. The effects were not consistent for three different positions of a speed skater. DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fbcf2d69-53a0-4098-bfb6-259105f1f6b9 ER - TY - JOUR TI - Optical tomography with the discontinuous Galerkin formulation of the radiative transfer equation in frequency domain DO - 10.1016/j.jqsrt.2012.03.003 AU - Balima, O. AU - Favennec, Y. AU - Boulanger, J. AU - Charette, A. T2 - Journal of Quantitative Spectroscopy and Radiative Transfer SN - 00224073 VL - 113 IS - 10 SP - 805 EP - 814 KW - Inverse problem; Adjoint method; Limited memory BFGS; Finite element; Filtering; Radiative transfer equation AB - Optical tomography is an inverse method of probing semi-transparent media with the help of light sources. The reconstruction of the optical properties usually employs finite volumes or continuous finite elements formulations of light transport as a forward model for the predictions. In a previous study, we have introduced a generalization of the inversion approach with finite elements formulations by using an integral form of the objective function. The novelty is that the surfaces of the detectors are taken into account in the reconstruction and compatibility is obtained for all finite element formulations. This present paper illustrates this new approach by developing a Discontinuous Galerkin formulation as a forward model for an optical tomography application in the frequency domain framework. Numerical tests are performed to gauge the accuracy of the method in recovering optical properties distribution with a gradient-based algorithm where the adjoint method is used to fastly compute the objective function gradient. It is seen that the reconstruction is accurate and can be affected by noise on the measurements as expected. Filtering of the gradient at each iteration of the reconstruction is used to cope with the ill-posed nature of the inverse problem and to improves the quality and accuracy of the reconstruction. DA - 2012/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 701a0079-3919-42e0-a2b3-3d82f7bfc732 ER - TY - JOUR TI - Nb-doped TiO2/carbon composite supports synthesized by ultrasonic spray pyrolysis for proton exchange membrane (PEM) fuel cell catalysts DO - 10.1016/j.jpowsour.2012.07.080 AU - Senevirathne, Keerthi AU - Neburchilov, Vladimir AU - Alzate, Vanesa AU - Baker, Ryan AU - Neagu, Roberto AU - Zhang, Jiujun AU - Campbell, Stephen AU - Ye, Siyu T2 - Journal of Power Sources SN - 0378-7753 VL - 220 SP - 1 EP - 9 KW - Ultrasonic spray pyrolysis; Microwave-assisted polyol reduction; Nb-doped TiO2; PtPd alloy catalysts; Oxygen reduction reaction; PEM fuel cells AB - In this paper we report the use of both ultrasonic spray pyrolysis and microwave-assisted polyol reduction methods to synthesize Nb-doped TiO2/carbon (25 wt% Nb0.07Ti0.93O2/75 wt% carbon) composite supports and Pt0.62Pd0.38 alloy catalysts, respectively. The physicochemical properties of the synthesized supports and their Pt0.62Pd0.38 supported catalysts are evaluated using several methods including XRD, TEM, BET surface area analysis, TGA, as well as ICP-MS elemental analysis. The electronic conductivities and thermal/chemical stabilities of the supports are also evaluated with respect to their possible use as catalyst supports. Electrochemical measurements for oxygen reduction activity of the Pt0.62Pd0.38 alloy catalysts supported on oxide/carbon composites are also carried out in order to check their suitability for possible PEM fuel cell applications. The results show that 20wt%Pt0.62Pd0.38/25 wt%(Nb0.07Ti0.93O2)-75 wt%C catalysts exhibit enhanced mass activities compared to those of commercially available 48wt% Pt/C and home-made 20wt% Pt62Pd38/C catalysts. DA - 2012/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 03bb9092-a38b-41af-b82a-92a101ca5265 ER - TY - JOUR TI - Impacts of operating conditions on the effects of chloride contamination on PEM fuel cell performance and durability DO - 10.1016/j.jpowsour.2012.07.003 AU - Li, Hui AU - Zhang, Shengsheng AU - Qian, Weimin AU - Yu, Yi AU - Yuan, Xiao-Zi AU - Wang, Haijiang AU - Jiang, Max AU - Wessel, Silvia AU - Cheng, Tommy T. H. T2 - Journal of Power Sources SN - 0378-7753 VL - 218 SP - 375 EP - 382 KW - Charge transfer; Chloride contamination; Electrochemical surface area; Mass transfer; PEM fuel cells AB - Chloride contaminated fuel and/or air streams in an operating proton exchange membrane fuel cell can cause significant adverse effects on fuel cell performance and durability. This paper reports investigations of chloride contamination effects on PEM fuel cell performance and durability under a wide range of operating conditions, using various in-situ diagnostic measurements. Increases in current density and Cl− concentration as well as decreases in fuel cell RH were found to enlarge the severity of the chloride contamination effect. Temperature was also found to have a significant influence on the contamination effect. Electrochemical impedance spectroscopy was used as a diagnostic tool during the contamination tests to explore changes in cell component resistances. The results indicated that chloride contamination causes predominantly an increase in charge transfer resistance as well as an increase in mass transfer resistance. The membrane resistance was not found to be impacted by chloride contamination. As measured by cyclic voltammetry, the presence of chloride in the air stream significantly reduced the cathode electrochemical surface area, and this reduction is believed to be due to the adsorption of chloride on the Pt surface causing active site blockage and accelerated Pt dissolution and agglomeration via the formation of Pt–Cl complexes. DA - 2012/11/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ef813b85-e04d-49b1-ba7b-c0c1481ed72e ER - TY - JOUR TI - High gravimetric capacity and long cycle life in Mn3O4/graphene platelet/LiCMC composite lithium-ion battery anodes DO - 10.1016/j.jpowsour.2012.03.055 AU - Lavoie, Nathalie AU - Malenfant, Patrick R. L. AU - Courtel, Fabrice M. AU - Abu-Lebdeh, Yaser AU - Davidson, Isobel J. T2 - Journal of Power Sources SN - 0378-7753 VL - 213 SP - 249 EP - 254 KW - Graphene; Manganese oxide; Li-ion batteries; Anode materials; Lithium carboxymethyl cellulose (LiCMC) AB - We report the synthesis, characterization and battery performance of a novel Mn3O4/graphene composite based on graphene platelets and also an Mn3O4/reduced-graphene-oxide composite for comparison. The electrodes were cast from aqueous dispersions in which lithium carboxymethyl cellulose was used as a binder thus enabling an aqueous based process for anode fabrication. The Mn3O4/graphene-platelet and the Mn3O4/reduced-graphene-oxide composites anode system possess high gravimetric capacities (∼700 mAh g−¹) and excellent cycling stability (>100 cycles). DA - 2012/09/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 03723074-e73a-4e8e-bcd4-b1026e3d941a ER - TY - JOUR TI - Application of a composite structure of carbon nanoparticles and Nb–TiO2 nanofibers as electrocatalyst support for PEM fuel cells DO - 10.1016/j.jpowsour.2012.02.093 AU - Bauer, Alex AU - Hui, Rob AU - Ignaszak, Anna AU - Zhang, Jiujun AU - Jones, Deborah J. T2 - Journal of Power Sources SN - 0378-7753 VL - 210 SP - 15 EP - 20 KW - Fuel cells; Conductive ceramics; Catalyst support; Nanofibers; Doped titanium oxide AB - Platinum catalyst nanoparticles (20 wt.%) were deposited on a mixed support, which consisted of 25 at.% Nb doped TiO2 nanofibers and carbon agglomerates. XRD analysis revealed that titania was present in the rutile phase. The catalyst was characterized electrochemically with respect to durability and oxygen reduction activity. Based on cyclic voltammetry tests, the Nb–TiO2/C supported catalyst was more stable compared to a commercially available carbon supported Pt catalyst (E-tek) over 1000 cycles. The apparent active Pt area decreased by 5% due to cycling, whereas in the case of Pt/C the decrease was 23%. The oxygen reduction performance was comparable for both cases. For example, during the anodic sweep the mass activity at 0.9 V vs. the reversible hydrogen electrode (RHE) was 19 A gPt−¹ and 20 A gPt−¹ for the freshly prepared in-house prepared and commercial catalysts, respectively. After the durability experiment both types of catalysts yielded a mass activity of 17 A gPt−¹. Fuel cell tests with a single cell configuration were also carried out with the Nb–TiO2/C supported catalyst on the cathode side (gas diffusion electrode), yielding a peak power density of 0.34 W cm−² at 75 °C when pure oxygen was supplied on the cathode side. DA - 2012/07/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f8cc491b-ed3c-45e7-b5d6-11b8570d35d7 ER - TY - JOUR TI - Membrane electrode assembly degradation under idle conditions via unsymmetrical reactant relative humidity cycling DO - 10.1016/j.jpowsour.2012.01.133 AU - Vengatesan, S. AU - Panha, Karachakorn AU - Fowler, Michael W. AU - Yuan, Xiao-Zi AU - Wang, Haijiang T2 - Journal of Power Sources SN - 03787753 VL - 207 SP - 101 EP - 110 KW - Durability; PEM failure modes; RH cycling; Idle condition; Membrane electrode assembly AB - The objective of this study is to investigate membrane electrode assembly (MEA) failure modes under accelerated test conditions via reactant relative humidity (RH) cycling. In this study, the anode and cathode underwent RH cycling in an unsymmetrical manner and the cell was run at a minimal “idle” current during endurance testing. The cell performance was monitored periodically and the degradation curve showed a difference in the anode and cathode induced RH cycling modes. Anode RH cycling had a more pronounced effect on MEA degradation than cathode RH cycling. Electrochemical diagnostic testing methods such as AC impedance and H2 crossover measurements revealed the degradation phenomena in more detail. The fluoride release data of the anode RH cycling cell showed a sudden increase in fluoride rate within a short period of endurance testing. The infrared imaging results revealed thinning and hotspot pinholes in the membrane, and ionomer delamination from the PTFE reinforcement layer was identified by scanning electron microscopy. The anode RH cycling cell had a shorter lifespan than the cell with cathode RH cycling, highlighting the significance of anode humidification for MEA durability. DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a5a9bce7-0a69-4693-80b3-7626971ea120 ER - TY - JOUR TI - Ex situ study of chloride contamination on carbon supported Pt catalyst DO - 10.1016/j.jpowsour.2012.01.063 AU - Lam, Alfred AU - Li, Hui AU - Zhang, Shengsheng AU - Wang, Haijiang AU - Wilkinson, David P. AU - Wessel, Silvia AU - Cheng, Tommy T. H. T2 - Journal of Power Sources SN - 03787753 VL - 205 SP - 235 EP - 238 KW - Polymer electrolyte membrane; Fuel cell; Chloride contamination; Electrochemical quartz crystal microbalance AB - The effect of ppm levels of chloride ions on a carbon supported platinum catalyst was examined using an ex situ electrochemical quartz crystal microbalance (EQCM) method. The dissolution of Pt as chloride complexes and the adsorption of chloride ions resulted in a loss of electrochemical surface area (ECSA) by 4%, 7% and 13% for the respective chloride concentrations of 500 ppm, 1000 ppm and 2000 ppm. Catalyst durability was examined by cyclic voltammetry (CV) and scanning electron microscopy (SEM) in the presence of 1000 ppm chloride. The beginning of life (BOL) ECSA of 8.1 cm² cm−² was significantly reduced to an end of life (EOL) ECSA of 3.2 cm² cm−² after cycling in the presence of 1000 ppm chloride. DA - 2012/05/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 60e9dd8b-ba9f-41ac-aaaf-6faf4338a1c3 ER - TY - JOUR TI - Nickel and cobalt oxide composite as a possible electrode material for electrochemical supercapacitors DO - 10.1016/j.jpowsour.2011.10.031 AU - Wang, Guoping AU - Zhang, Lei AU - Kim, Jenny AU - Zhang, Jiujun T2 - Journal of Power Sources SN - 03787753 VL - 217 SP - 554 EP - 561 KW - Electrochemical supercapacitor; Ni oxide; Co oxide; Composite electrode material AB - In this paper, a composite material, Ni0.37Co0.63(OH)2, is synthesized using the chemical precipitation method with the purpose to develop electrode materials for supercapacitors. Physical characterization using XRD, EDX, and SEM show that Ni0.37Co0.63(OH)2 possesses an amorphous structure, which leads to high specific capacitance of 1840 F g−¹ in the potential window of 0–1.5 V. Cyclic voltammetry methods are employed to characterize the electrochemical properties of this electrode material in a N2-saturated alkaline solution. The results demonstrate that this material could give a two-electron redox process accompanied by two OH− ions. Cyclic voltammogram curves recorded for this Ni0.37Co0.63(OH)2 material are used to measure the specific capacitances at different potential scan rates. To validate this material for supercapacitor applications, charging/discharging tests are also conducted. DA - 2012/11/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 24d1ea46-aa3f-46ad-8464-f459f04a9c86 ER - TY - JOUR TI - Pulsed laser deposition of cobalt-doped manganese oxide thin films for supercapacitor applications DO - 10.1016/j.jpowsour.2011.10.008 AU - Yang, Dongfang T2 - Journal of Power Sources SN - 0378-7753 VL - 198 SP - 416 EP - 422 KW - Electrochemical capacitor; Supercapacitor; Ultracapacitor; Pulsed laser deposition; Cobalt-doped manganese oxides; Thin films AB - Thin films of manganese oxide doped with various percentages of cobalt oxide were grown by pulsed laser deposition on silicon wafers and stainless steel substrates. The films were characterized by X-ray diffraction and field emission scanning electron microscopy in order to identify their phases and microstructures. The pseudo-capacitance behavior of the Co-doped manganese oxide films were then evaluated using electrochemical cyclic voltammetry in an aqueous electrolyte. Their specific current and capacitance determined by electrochemical measurements were compared with undoped manganese oxide films, and the results show that Co-doped amorphous MnOx films have significantly higher specific current and capacitance than undoped amorphous MnOx films. The 3.0% Co-doped MnOx (i.e., Mn0.970Co0.030Ox) film had the highest specific capacitance of 99 F g−¹ at a 5 mV s−¹ scan rate. However, Co-doped crystalline Mn2O3 films did not show an improvement in specific current and capacitance compared with undoped Mn2O3 crystalline films. High Co doping level (20.7% doped) in the crystalline Mn2O3 films actually decreased both the specific current and capacitance values. These findings demonstrate that elemental doping is an effective way to improve the performance of pseudo-capacitive metal oxides. DA - 2012/01/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : de506bf9-4bc7-4cfc-8d2c-b2777b874345 ER - TY - JOUR TI - The calcium-sensing receptor: a novel Alzheimer's disease crucial target? DO - 10.1016/j.jns.2012.07.031 AU - Armato, Ubaldo AU - Bonafini, Clara AU - Chakravarthy, Balu AU - Pacchiana, Raffaella AU - Chiarini, Anna AU - Whitfield, James F. AU - Dal Prà, Ilaria T2 - Journal of the Neurological Sciences T3 - Sixth International Congress on Vascular Dementia, 2011, Riga, Latvia SN - 0022-510X VL - 322 IS - 1-2 SP - 137 EP - 140 KW - Alzheimer's disease; Amyloid-β peptides; Calcium-sensing receptor; Human astrocytes AB - Alzheimer's disease (AD) is the most common human neurodegenerative ailment, the most prevalent (> 95%) late-onset type of which has a still uncertain etiology. The progressive decline of cognitive functions, dementia, and physical disabilities of AD is caused by synaptic losses that progressively disconnect key neuronal networks in crucial brain areas, like the hippocampus and temporoparietal cortex, and critically impair language, sensory processing, memory, and conscious thought. AD's two main hallmarks are fibrillar amyloid-β (fAβ) plaques in extracellular spaces and intracellular accumulation of fAβ peptides and neurofibrillary tangles (NFTs). It is still undecided whether either or both these AD hallmarks cause or result from the disease. Recently, the dysregulation of calcium homeostasis has been advanced as a novel cause of AD. In this case, a suitable candidate of AD driver would be the Aβ peptides–binding/activated calcium-sensing receptor (CaSR), whose intracellular signalling is triggered by Aβ peptides. In this review, we briefly discuss CaSR's roles in normal adult human astrocytes (NAHAs) and their possible impacts on AD. DA - 2012/11/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6a063edd-d2c0-4598-be7e-72df3bdaef01 ER - TY - JOUR TI - Comparing gray and white matter fMRI activation using asymmetric spin echo spiral DO - 10.1016/j.jneumeth.2012.06.014 AU - McWhinney, Sean R. AU - Mazerolle, Erin L. AU - Gawryluk, Jodie R. AU - Beyea, Steven D. AU - D’arcy, Ryan C. N. T2 - Journal of Neuroscience Methods SN - 0165-0270 VL - 209 IS - 2 SP - 351 EP - 356 KW - Asymmetric spin echo; fMRI; White matter; Contrast-to-noise AB - Recent developments have shown that it is possible to detect functional magnetic resonance imaging (fMRI) activation in white matter (WM). Enhanced sensitivity to WM fMRI signals has been associated with the asymmetric spin echo (ASE) spiral sequence. The ASE spiral sequence produces three consecutive images that have equal blood-oxygen level-dependent (BOLD) contrast but increasing T2 contrast. The current study evaluated whether ASE spiral sensitivity differed between white and gray matter in the corpus callosum, superior parietal lobes, cingulate gyrus, and inferior frontal lobes. Contrast and noise were compared across the three images for each region. Results showed increasing gains in functional contrast in both white and gray matter as a function of T2 contrast. The third image, with the most T2 contrast, showed the largest increase in contrast, while changes in noise were maintained. The results suggest that ASE spiral increases fMRI sensitivity globally through the addition of T2 weighted contrast. DA - 2012/08/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ab9d44d7-ea8d-413d-a13a-d67ee8587dda ER - TY - JOUR TI - A comparison of MR imaging of a mouse model of glioma at 0.2T and 9.4T DO - 10.1016/j.jneumeth.2011.10.030 AU - Blasiak, Barbara AU - Volotovskyy, Vyacheslav AU - Deng, Charlie AU - Foniok, Tadeusz AU - Tomanek, Boguslaw T2 - Journal of Neuroscience Methods SN - 01650270 VL - 204 IS - 1 SP - 118 EP - 123 KW - MRI; Glioma; Brain; Low field MRI; RF coil AB - Both 0.2 T and 9.4 T MRI systems were used to image a mouse model of glioma. RF coils were designed for both fields. A spin-echo, multi-echo pulse sequence was used to determine T2 relaxation times of both brain and tumor tissues. Contrast-to-noise ratio was calculated based on the selected echo time. The results showed that 0.2 T is suitable for mouse model imaging, however total scan time must be long to achieve high enough SNR. T2 relaxation times of the tumor and brain tissues can be measured at 0.2 T and are 2.1 and 1.8 times respectively longer at 0.2 T than at 9.4 T. Contrast to noise ratio for tumor and brain was better at high field than at the low field. We concluded that 0.2 T may be used to study mouse model of glioma using spin echo pulse sequence, yet the total scan time is long (about 40 min), resolution is lower (∼250 μm × 250 μm) and slice thickness (3 mm) must be large enough to obtain sufficient SNR. DA - 2012/02/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c26b08d9-0eaf-41e2-9620-d1f05e2667ca ER - TY - JOUR TI - Infrared spectra of rare gas–carbon disulfide complexes: He–CS2, Ne–CS2, and Ar–CS2 DO - 10.1016/j.jms.2012.10.002 AU - Mivehvar, F. AU - Lauzin, Clément AU - Mckellar, A. R. W. AU - Moazzen-Ahmadi, N. T2 - Journal of Molecular Spectroscopy SN - 00222852 VL - 281 SP - 24 EP - 27 KW - Carbon disulfide; Spectrum; Dimer; van der Waals; Infrared; Supersonic jet AB - Spectra of the weakly-bound van der Waals complexes Ar–CS2, Ne–CS2, and He–CS2 are studied in the region of the CS2ν3 fundamental band (≈1535 cm−¹) using a tunable diode laser to probe a pulsed supersonic expansion from a slit jet nozzle. He–CS2 is also observed in the ν1 + ν3 region (≈2185 cm−¹). These are the first reported spectra for rare gas–CS2 complexes, which are shown to have T-shaped structures similar to their CO2 analogs but with intermolecular separations which are 0.2–0.3 Å greater. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8ce2da1f-51cd-4945-b74c-b08801bce7fc ER - TY - JOUR TI - Infrared spectra of the Ne2–N2O, Ar2–N2O trimers DO - 10.1016/j.jms.2012.07.007 AU - Rezaei, M. AU - Michaelian, K. H. AU - Mckellar, A. R. W. AU - Moazzen-Ahmadi, N. T2 - Journal of Molecular Spectroscopy SN - 00222852 VL - 278 SP - 17 EP - 22 KW - Argon; Neon; Nitrous oxide; Spectrum; Dimer; Trimer; van der Waals AB - Spectra of the van der Waals trimers Ar2–N2O and Ne2–N2O are studied in the region of the N2O ν1 fundamental (≈2220 cm−¹) using a tunable quantum cascade laser to probe a pulsed supersonic expansion from a slit jet nozzle. Improved data are obtained for the dimers Ar–N2O and Ne–N2O, and the Q-branch of Ar3–N2O is tentatively assigned. The vibrational shifts for Nen–N2O are almost exactly linear for n = 0–2. However, for Arn–N2O the n = 2 band origin is slightly blue-shifted compared to the linear prediction, and the n = 3 origin (if correct) is more significantly blue-shifted (by 0.09 cm−¹). DA - 2012/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 99b71464-9808-4e5c-97c4-11cde4379df1 ER - TY - JOUR TI - Infrared spectra of acetylene–water complexes: C2D2–H2O, C2D2–HDO, and C2D2–D2O DO - 10.1016/j.jms.2011.12.003 AU - Rezaei, Mojtaba AU - Moazzen-Ahmadi, N. AU - Mckellar, A. R. W. T2 - Journal of Molecular Spectroscopy SN - 00222852 VL - 272 IS - 1 SP - 19 EP - 22 KW - Acetylene–water complex; Infrared; Dimer; Jet spectroscopy; High resolution; Van der Waals AB - Infrared spectra of C2D2–water complexes are studied in the 4.1 μm region of the C2D2 ν3 fundamental band using a tunable diode laser source to probe a pulsed supersonic slit jet. Relatively large vibrational red shifts (−27.7 to −28.0 cm−¹) are observed which are more easily interpretable than for the analogous C2H2 vibration thanks to the absence of Fermi resonance effects for C2D2. Noticeable homogeneous line broadening leads to estimates of upper state predissociation lifetimes of about 0.5, 0.9 and 1.1 ns for C2D2–H2O, –HDO, and –D2O, respectively. Transitions involving Ka = 0 and 1 levels are observed for C2D2–HDO, but there is a puzzling absence of Ka = 1 for C2D2–H2O and C2D2–D2O. DA - 2012/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5af1f659-fe97-43b0-b9c9-11b7eb2f8304 ER - TY - JOUR TI - Influence of overlap between the laser beam tracks on surface quality in laser polishing of AISI H13 tool steel DO - 10.1016/j.jmapro.2012.09.004 AU - Hafiz, Abdullah M. Khalid AU - Bordatchev, Evgueni V. AU - Tutunea-Fatan, Remus O. T2 - Journal of Manufacturing Processes T3 - 40th North American Manufacturing Research Conference (NAMRC), June 5–8, 2012, South Bend, Indiana, U.S.A. SN - 15266125 VL - 14 IS - 4 SP - 425 EP - 434 KW - Laser polishing; Surface quality; Material ratio function; Power spectral density; Transfer function AB - Polishing by laser beam radiation is a novel manufacturing process to modify the initial surface topography in order to achieve a desired level of surface finish. The performance of laser polishing (LP) is determined by an optimum combination of several key process parameters. In this regard, the overlap between two successive laser beam tracks is one of the important LP process parameters, which has a significant effect over the final surface quality. In the current study, influence of overlap between the laser beam tracks on surface quality was experimentally investigated during the laser polishing of AISI H13 tool steel. Surface areas were polished by using four different overlap percentages (e.g. 80%, 90%, 95%, and 97.5%) while applying the same energy density. The improvement of surface quality was estimated through the analysis of line profiling surface roughness Ra, areal topography surface roughness Sa, and material ratio function. Also, individual components of the surface quality, e.g. waviness and roughness, and their evolution during LP were statistically analyzed using the power spectral density and the transfer functions. Finally, as an example of the best achieved LP result, flat surface area was polished using optimum set of the process parameters improving surface quality by 86.7% through the reduction of an areal topography surface roughness Sa from 1.35 μm to 0.18 μm. DA - 2012/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 00512689-bb0d-4f78-9757-fb6f86c0b94c ER - TY - JOUR TI - American ginseng inhibits vascular smooth muscle cell proliferation via suppressing Jak/Stat pathway DO - 10.1016/j.jep.2012.09.046 AU - Wu, Qi AU - Wang, Wenjuan AU - Li, Siying AU - Nagarkatti, Prakash AU - Nagarkatti, Mitzi AU - Windust, Anthony AU - Wang, Xing li AU - Tang, Dongqi AU - Cui, Taixing T2 - Journal of Ethnopharmacology SN - 0378-8741 VL - 144 IS - 3 SP - 782 EP - 785 KW - Panax quinquefolius; American ginseng; Jak; Stat; Vascular smooth muscle cells; Proliferation AB - Ethnopharmcological relevance - Ginseng, a folk medicine which has been used for thousands of years in Asia, has been promoted for the treatment or prevention of health problems including cardiovascular disease. However, the molecular mechanism of ginseng-induced cardiovascular protection is unclear. Thus, we investigated signaling mechanism by which American ginseng inhibits vascular smooth muscle cell (VSMC) proliferation, a key feature of diverse vascular disease. Materials and methods - A standardized crude extract of American ginseng was supplied by the National Research Council of Canada, Institute for National Measurement Standards. Rat aortic smooth muscle cells (RASMCs) were exposed to fetal bovine serum (FBS), platelet derived growth factor (PDGF), insulin, or angiotensin II (Ang II) to induce proliferation that was examined by measuring DNA synthesis and cell numbers. Western blot was applied to determine the activations of Jak, Stat, Akt, and ERK. Results - American ginseng inhibited RASMC proliferation induced by FBS, PDGF, insulin or Ang II. American ginseng slightly increased both basal and FBS-, PDGF- or Ang II-induced activities of Akt and ERK in RASMCs; however, it dramatically inhibited the activation of Jak2 and Stat3. Conclusion - These results demonstrate that American ginseng inhibits VSMC proliferation through suppressing the Jak/Stat pathway. DA - 2012/12/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 36c162c1-79bd-4b06-aee3-a35e274bb576 ER - TY - JOUR TI - Molecular dynamics Gibbs free energy calculations for CO2 capture and storage in structure I clathrate hydrates in the presence of SO2, CH4, N2, and H2S impurities DO - 10.1016/j.jct.2011.08.025 AU - Nohra, Michael AU - Woo, Tom K. AU - Alavi, Saman AU - Ripmeester, John A. T2 - The Journal of Chemical Thermodynamics SN - 0021-9614 VL - 44 IS - 1 SP - 5 EP - 12 KW - Clathrate hydrates; Molecular dynamics; Free energy calculations; Carbon dioxide sequestration; Thermodynamic integration; Carbon capture and storage; Sulfur dioxide; Flue gas DA - 2012/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : dadd53cc-0315-4cf4-85e0-5abec1325282 ER - TY - JOUR TI - Influence of carbon coated pBN crucible on crystal growth of Cd0.9Zn0.1Te for radiation detector applications DO - 10.1016/j.jcrysgro.2012.03.034 AU - Crocco, J. AU - Carcelen, V. AU - Methven, B. AU - Gallardo, I. AU - Bensalah, H. AU - Zheng, Q. AU - Rivas, I. AU - Moreno, F. AU - Vela, O. AU - Diéguez, E. T2 - Journal of Crystal Growth SN - 00220248 VL - 349 IS - 1 SP - 61 EP - 67 KW - Gradient freeze technique; Impurities; Cadmium compounds; Nitrides AB - In the Bridgman and Vertical Gradient Freeze (VGF) techniques, it is common to use a high purity crucible for crystal growth. One disadvantage of pBN crucibles is associated with the crucible material interacting with the melt during the growth cycle. Using pBN crucibles for the growth of CZT, we have observed that the crucible does in fact interact with the CZT melt. To prevent this interaction, a vacuum carbon coating system for applying a carbon coating to pBN crucibles has been developed. The effects of crucible use with time are studied, as are the compositional and device properties of the bulk material. GDMS measurements are used to investigate on broron and nitrogen content, among other trace impurities found in the crystal. Devices harvested from ingots grown using cc-pBN exhibit high resistivity and good functionality as room temperature gamma ray detectors. DA - 2012/06/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4585cba5-071e-40ed-8b2d-359ead00da5f ER - TY - JOUR TI - Multiwafer zinc diffusion in an OMVPE reactor DO - 10.1016/j.jcrysgro.2011.10.006 AU - Pitts, O. J. AU - Benyon, W. AU - Goodchild, D. AU - Springthorpe, A. J. T2 - Journal of Crystal Growth T3 - 18th American Conference on Crystal Growth and Epitaxy (ACCGE-18), July 31 to August 5, 2011, Monterey, California, U.S.A. SN - 0022-0248 VL - 352 IS - 1 SP - 249 EP - 252 KW - Diffusion; Metalorganic chemical vapor deposition; Metalorganic vapor phase epitaxy; Organometallic vapor phase epitaxy; Semiconducting indium phosphide AB - We study diffusion of zinc into InP in a multiwafer OMVPE reactor using dimethylzinc as the diffusant source. The resulting diffusion profiles are measured by electrochemical capacitance–voltage profiling and by secondary ion mass spectrometry and compared with cleaved cross-sections imaged by scanning electron microscopy. Very good uniformity of the diffusion profile is achieved, with variation across a 3 in. wafer as little as 5%. The dependence of the diffusion depth and Zn concentration on the diffusion temperature, partial pressure of dimethylzinc, and diffusion time are reported. We observe an enhancement of the diffusion depth in area-selective diffusion of planar devices, compared to the depth obtained for blanket diffusion. DA - 2012/08/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 988768e6-e2a2-4d1d-884b-e56145ccffc4 ER - TY - JOUR TI - Expression and characterization of recombinant human alpha-antitrypsin in transgenic rice seed DO - 10.1016/j.jbiotec.2013.01.008 AU - Zhang, Liping AU - Shi, Jingni AU - Jiang, Daiming AU - Stupak, Jacek AU - Ou, Jiquan AU - Qiu, Qichuan AU - An, Na AU - Li, Jianjun AU - Yang, Daichang T2 - Journal of Biotechnology SN - 0168-1656 VL - 164 IS - 2 SP - 300 EP - 308 KW - Recombinant human alpha-1-antitrypsin; Rice endosperm; Plant N-glycan modification; Protein expression and processing; Protein trafficking AB - Human alpha-antitrypsin (AAT) is the most abundant circulating protease inhibitor in the human plasma. It is produced in the liver and exerts a primary physiological role as inhibitor for the neutrophil elastase in the lung. Individuals with one or several gene mutations in AAT causing reduction of the protein are related to lung, liver and pancreatic emphysema diseases and are treated lifelong with infusions of human plasma-derived AAT. Due to shortage of plasma and low expression levels of recombinant AAT in conventional gene expression systems, we explored the possibility to produce recombinant AAT in rice grains (Oryza sativa AAT, OsrAAT). An expression level of up to 2.24 g/kg brown rice and a final recovery of purified 0.366 g/kg OsrAAT has been obtained. OsrAAT has the same secondary structure and protease inhibitory activity as plasma-derived AAT (pAAT), but was highly heterogeneous with regard to glycan modifications. Thus 32.8% of OsrAAT were glycosylated and 67.2% were free of glycans as determined by MALDI-MS. Of the N-glycan structures 64.8% were vacuole-specific paucimannosidic molecules. Immune electron microscopy located OsrAAT in the endoplasmic reticulum lumen as precursor-accumulating (PAC)-like vesicle structures. The pharmacokinetic study indicated that the half-life of OsrAAT was prolonged, while the clearance rate was faster than that of pAAT in vivo. The results demonstrate that rice endosperm is a promising system to express this biopharmaceutical protein. DA - 2012/12/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 82b31596-b155-4589-93dd-4b757bb23912 ER - TY - JOUR TI - Studies of CoSn grains in the carbon matrix structure of nanostructured tin–cobalt–carbon DO - 10.1016/j.jallcom.2012.07.042 AU - Ferguson, P. P. AU - Fleischauer, M. D. AU - Laforge, J. M. AU - Todd, A. D. W. AU - Li, P. AU - Dahn, J. R. T2 - Journal of Alloys and Compounds SN - 09258388 VL - 541 SP - 168 EP - 172 KW - Tin cobalt carbon; Small angle neutron scattering; Transmission electron microscopy; Li-ion battery negative electrode; Sputtering; Mechanical alloying AB - Small angle neutron scattering (SANS) and transmission electron microscopy (TEM) have been used to qualitatively analyze the structure of Sn30Co30C40 alloys produced by vertical axis mechanical attriting to those produced by magnetron sputter deposition. From SANS and TEM, CoSn grains embedded in a carbon matrix structure were observed for all samples. The size of CoSn grains in the attrited samples was approximately 10 ± 3 nm by both TEM and SANS, while that of the sputtered samples was about 7 times smaller. DA - 2012/11/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 66b52c50-fb1d-47a0-a118-68e0cc2eeaed ER - TY - JOUR TI - Effect of cold rolling on hydrogen sorption properties of die-cast and as-cast magnesium alloys DO - 10.1016/j.jallcom.2012.01.049 AU - Amira, S. AU - Huot, J. T2 - Journal of Alloys and Compounds SN - 09258388 VL - 520 SP - 287 EP - 294 KW - Severe Plastic Deformation (SPD); Magnesium alloys; Hydrogen storage; Casting AB - The effect of cold rolling, as an activation process of materials aimed to hydrogen storage application, was applied to some cast magnesium alloys. The alloys studied in this work are AZ91D and three experimental creep resistant magnesium alloys (MRI153, AXJ530, ZAEX10430) in the as-cast and die-cast states. Experiments showed that AZ91D, MRI153 and ZAEX10430 have faster absorption/desorption kinetic than as-cast pure magnesium. On the other hand, AXJ530 showed the worst hydrogen storage properties. These results were attributed to a possible beneficial effect of aluminum and zinc as alloying elements. Segregation inside primary α-Mg grains may explain the difference of hydrogen storage properties between as-cast and die-cast alloys. DA - 2012/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ad03fc6d-6e50-4c88-82c5-58b24622192d ER - TY - JOUR TI - Performance-based parameter tuning method of model-driven PID control systems DO - 10.1016/j.isatra.2012.02.005 AU - Zhao, Y. M. AU - Xie, W. F. AU - Tu, X. W. T2 - ISA Transactions SN - 0019-0578 VL - 51 IS - 3 SP - 393 EP - 399 KW - MD TDOF PID; Modified smith predictor; PD feedback; Q filter and set-point filter AB - In this paper, performance-based parameter tuning method of model-driven Two-Degree-of-Freedom PID (MD TDOF PID) control system has been proposed to enhance the control performances of a process. Known for its ability of stabilizing the unstable processes, fast tracking to the change of set points and rejecting disturbance, the MD TDOF PID has gained research interest recently. The tuning methods for the reported MD TDOF PID are based on internal model control (IMC) method instead of optimizing the performance indices. In this paper, an Integral of Time Absolute Error (ITAE) zero-position-error optimal tuning and noise effect minimizing method is proposed for tuning two parameters in MD TDOF PID control system to achieve the desired regulating and disturbance rejection performance. The comparison with Two-Degree-of-Freedom control scheme by modified smith predictor (TDOF CS MSP) and the designed MD TDOF PID tuned by the IMC tuning method demonstrates the effectiveness of the proposed tuning method. DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cb5dce10-c32a-4e6f-8331-71f39a11993e ER - TY - JOUR TI - Calculations of gas radiation heat transfer in a two-dimensional rectangular enclosure using the line-by-line approach and the statistical narrow-band correlated-k model DO - 10.1016/j.ijthermalsci.2012.04.003 AU - Chu, Huaqiang AU - Liu, Fengshan AU - Zhou, Huaichun T2 - International Journal of Thermal Sciences SN - 1290-0729 VL - 59 SP - 66 EP - 74 KW - Non-gray gas radiation; LBL calculations; SNBCK model AB - Radiation heat transfer in a two-dimensional rectangular enclosure containing CO2/H2O/N2 mixtures was calculated using the line-by-line and the statistical narrow-band correlated-k models. The radiative transfer equation was solved using the discrete ordinates method along with the T7 quadrature scheme. The updated HITEMP spectroscopic database, HITEMP2010, was employed in line-by-line calculations to obtain the most accurate line-by-line results. The statistical narrow-band model parameters of Sourfiani and Taine [IJHMT 40, 987–991, 1997] were used to obtain the statistical narrow-band correlated-k model results. Calculations were carried out for five test cases involving isothermal/non-isothermal and homogeneous/inhomogeneous CO2/N2, H2O/N2, and CO2/H2O/N2 mixtures. The present line-by-line results can serve as benchmark results for the purpose of validating other approximate models in gas radiation heat transfer calculations in two-dimensional enclosures. Results of the statistical narrow-band correlated-k model are in good agreement with those of the line-by-line method in all the test cases. The statistical narrow-band correlated-k model was found sufficiently accurate to generate benchmark solutions in multi-dimensional gas radiation transfer problems where line-by-line calculations are infeasible due to excessively long computing time. DA - 2012/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f1b09c5f-44d3-4256-b1e0-a9dd45348a2c ER - TY - JOUR TI - Assessment of silk fibroin for the repair of buccal mucosa in a rat model DO - 10.1016/j.ijom.2011.11.016 AU - Ge, Z. AU - Yang, Q. AU - Xiang, X. AU - Liu, K.-Z. T2 - International Journal of Oral and Maxillofacial Surgery SN - 0901-5027 VL - 41 IS - 5 SP - 673 EP - 680 KW - silk fibroin; buccal mucosa; tissue repair; tissue engineering AB - This study evaluated the effectiveness of silk fibroin materials for wound repair confined to the buccal mucosa in a rat model by assessing several key clinical parameters and the associated local and systemic immune response. Ninety male SD rats were subjected to microscopic oral surgery to establish a full thickness wound on the buccal mucosa. Rats were randomly divided into three groups based on the treatments received: group A, covered with polyporous silk fibroin scaffold; group B, repaired with crosslinking silk fibroin film; and group C, control. Visual observation of the wounds suggests that wound shrinkage 5 days after the operation was significantly lower in both silk fibroin repaired groups (A and B) than that in the controls. The distribution of inflammatory neutrophils in group A was significantly lower than those in the control group throughout the entire study. The percentage of fibroblasts and capillary endothelia (CD34+), and the subgroups of peripheral lymphocytes (CD3+, CD4+, CD8+) were similar amongst the groups. The results revealed that placement of silk fibroin in an oral buccal defect can reduce the degree of wound shrinkage and enhance the growth of mucosal epithelial cells without any local or systemic immunological incompatibility. DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0804cff2-2e6f-4e29-a24a-2e92bbcca77a ER - TY - JOUR TI - An integrated multi-level watershed-reservoir modeling system for examining hydrological and biogeochemical processes in small prairie watersheds DO - 10.1016/j.watres.2011.12.021 AU - Zhang, Hua AU - Huang, Guo H. AU - Wang, Dunling AU - Zhang, Xiaodong AU - Li, Gongchen AU - An, Chunjiang AU - Cui, Zheng AU - Liao, Renfei AU - Nie, Xianghui T2 - Water Research SN - 00431354 VL - 46 IS - 4 SP - 1207 EP - 1224 KW - Prairie watershed; Multi-level; Eutrophication; Reservoir; Simulation AB - Eutrophication of small prairie reservoirs presents a major challenge in water quality management and has led to a need for predictive water quality modeling. Studies are lacking in effectively integrating watershed models and reservoir models to explore nutrient dynamics and eutrophication pattern. A water quality model specific to small prairie water bodies is also desired in order to highlight key biogeochemical processes with an acceptable degree of parameterization. This study presents a Multi-level Watershed-Reservoir Modeling System (MWRMS) to simulate hydrological and biogeochemical processes in small prairie watersheds. It integrated a watershed model, a hydrodynamic model and an eutrophication model into a flexible modeling framework. It can comprehensively describe hydrological and biogeochemical processes across different spatial scales and effectively deal with the special drainage structure of small prairie watersheds. As a key component of MWRMS, a three-dimensional Willows Reservoir Eutrophication Model (WREM) is developed to addresses essential biogeochemical processes in prairie reservoirs and to generate 3D distributions of various water quality constituents; with a modest degree of parameterization, WREM is able to meet the limit of data availability that often confronts the modeling practices in small watersheds. MWRMS was applied to the Assiniboia Watershed in southern Saskatchewan, Canada. Extensive efforts of field work and lab analysis were undertaken to support model calibration and validation. MWRMS demonstrated its ability to reproduce the observed watershed water yield, reservoir water levels and temperatures, and concentrations of several water constituents. Results showed that the aquatic systems in the Assiniboia Watershed were nitrogen-limited and sediment flux played a crucial role in reservoir nutrient budget and dynamics. MWRMS can provide a broad context of decision support for water resources management and water quality protection in the prairie region. DA - 2012/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 889f7417-6242-4add-ab52-0736ddacabaf ER - TY - JOUR TI - Relative permeability for two-phase flow through corrugated tubes as model porous media DO - 10.1016/j.ijmultiphaseflow.2012.07.005 AU - Ahmadlouydarab, Majid AU - Liu, Zhong-Sheng (Simon) AU - Feng, James J. T2 - International Journal of Multiphase Flow SN - 0301-9322 VL - 47 SP - 85 EP - 93 KW - Interfacial flow; Viscous coupling; Pore-scale simulation; Moving contact line; Cahn–Hilliard model; Lubrication effect AB - We report finite-element simulations of gas–liquid two-phase flows through a model porous medium made of corrugated tubes. By resolving the pore-scale fluid dynamics and interfacial morphology, we compute the relative permeability of the porous medium by averaging over a pore-size-distribution of a real porous medium. A constant pressure gradient is applied on both fluids to simulate a pressure-driven creeping flow, and a diffuse-interface model is used to compute the interfacial evolution and the contact line motion. We observe a number of flow regimes in the micro-pores, depending on the pore size, imposed pressure gradient, and other geometric and physical parameters. The flow rates vary nonlinearly with the pressure gradient, and the extended Darcy’s law does not hold in general. The interaction between the two phases, known as viscous coupling, is a prominent feature of the process. As a result, the relative permeability depends not only on saturation, but also on the capillary number, viscosity ratio, wettability of the solid wall, pore geometry, and the initial configuration. The effects of these factors are explored systematically and compared with previous studies. DA - 2012/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9b43d2a2-6608-4199-ae93-a957008a87f7 ER - TY - JOUR TI - Far- and mid-infrared photoacoustic spectra of tetracene, pentacene, perylene and pyrene DO - 10.1016/j.vibspec.2011.10.011 AU - Michaelian, K.H. AU - Wen, Q. AU - Billinghurst, B.E. AU - Shaw, J.M. AU - Lastovka, V. T2 - Vibrational Spectroscopy SN - 09242031 VL - 58 SP - 50 EP - 56 KW - Photoacoustic infrared spectroscopy; Aromatic hydrocarbons; DFT calculations AB - Far- and mid-infrared photoacoustic (PA) spectra of tetracene, pentacene, perylene and pyrene were acquired in this study. Far-infrared data were obtained at wavenumbers down to ∼80 cm−1 using large-amplitude phase modulation in a step-scan spectrometer; many previously unreported bands were observed in these spectra. For each compound, the fingerprint region of the mid-infrared spectrum (approximately 400–2000 cm−1) contained a large number of bands correlated with vibrations that are predicted to be either infrared or Raman active. In addition, numerous combination and overtone bands appeared in the mid-infrared spectra. This PA investigation provides the most detailed spectral data known for these four aromatic compounds. DA - 2012/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 370146cb-6459-4f58-addd-e43d171ad51e ER - TY - JOUR TI - Estimating microbial electrolysis cell (MEC) investment costs in wastewater treatment plants: case study DO - 10.1016/j.ijhydene.2012.09.157 AU - Escapa, A. AU - Gómez, X. AU - Tartakovsky, B. AU - Morán, A. T2 - International Journal of Hydrogen Energy T3 - 2011 International Workshop on Molten Carbonates & Related Topics, March 21-22, 2011, Paris, France SN - 03603199 VL - 37 IS - 24 SP - 18641 EP - 18653 KW - Microbial electrolysis cell; Costs estimation; Hydrogen; Domestic wastewater AB - Microbial electrolysis represents a new approach for harnessing the energy contained in the organic matter of wastewater. However, before this approach can be implemented on a practical basis, a cost-effective manufacturing process for microbial electrolysis cells (MECs) must be developed. The objective of this study is to estimate an acceptable purchase cost of an MEC reactor for a domestic wastewater treatment plant. We estimate that for a full-scale MEC operating at a current density of 5 A ma−² (amperes per square meter of anode) and an energy consumption of 0.9 kWh kg-COD−¹ (kilowatt-hour per kg of removed chemical oxygen demand (COD)), a cost of €1220 ma−³ (euro per m³ of anodic chamber) can be established as a target purchase cost at which a break-even point is reached after 7 years. DA - 2012/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 02e05713-3572-4d41-895d-13cc70fe18e4 ER - TY - JOUR TI - Highly active electrocatalysts for oxygen reduction from carbon-supported copper-phthalocyanine synthesized by high temperature treatment DO - 10.1016/j.ijhydene.2012.07.046 AU - Ding, Lei AU - Qiao, Jinli AU - Dai, Xianfeng AU - Zhang, Jing AU - Zhang, Jiujun AU - Tian, Binglun T2 - International Journal of Hydrogen Energy T3 - 4th National - 3rd Latin American Conference on Hydrogen and Sustainable Energy Sources (HYFUSEN), June 6-9, 2011, Mar Del Plata, Argentina SN - 0360-3199 VL - 37 IS - 19 SP - 14103 EP - 14113 KW - Copper phthalocyanine; Electrocatalysts; Oxygen reduction reaction; Heat treatment; Alkaline fuel cell AB - The active, carbon-supported copper phthalocyanine (CuPc/C) nano-catalyst, as a novel cathode catalyst for oxygen reduction reaction, is synthesized via a combined solvent-impregnation along with the high temperature treatment. The catalytic activities of both pyrolyzed and unpyrolyzed catalysts are screened by linear sweep voltammetry (LSV) employing a rotating disk electrode (RDE) technique to quantitatively obtain the oxygen reduction reaction (ORR) kinetic constants and the reaction mechanisms. The results show that heat-treatment can significantly improve the ORR activity of the catalyst, and the optimal heat-treated temperature is around 800 °C, under which, an onset potential of 0.10 V and a half-wave potential of −0.05 V are achieved in alkaline electrolyte. Besides the ORR kinetic rate is increased, the ORR electron transfer number is also increased from 2.5 to 3.6 with increasing heat-treatment temperature from 600 to 800 °C. Also, the effect of catalyst loading in the catalyst layer on the corresponding ORR activity is also studied, and finds that increasing the catalyst loading, the catalyzed ORR kinetic current density can be significantly increased. For a fully understanding of this heat-treatment temperature effect, XRD, TEM, SEM–EDX, TG and XPS are used to identify the catalyst structure and composition. TG results demonstrated that the presence of Cu prevents phthalocyanine from thermal decomposition, thus contribute to higher nitrogen content which can form more Cu–Nx activity sites for the ORR. XPS analysis indicates that both pyridinic-N and graphitic-N may be responsible for the enhanced ORR activity. DA - 2012/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 160974e3-2acc-4a68-a80d-4d6f0ff4d7b1 ER - TY - JOUR TI - Current mapping of a proton exchange membrane fuel cell with a segmented current collector during the gas starvation and shutdown processes DO - 10.1016/j.ijhydene.2012.07.023 AU - Yu, Yi AU - Yuan, Xiao-Zi AU - Li, Hui AU - Gu, Elton AU - Wang, Haijiang AU - Wang, Guangjin AU - Pan, Mu T2 - International Journal of Hydrogen Energy T3 - The 2011 Asian Bio-Hydrogen and Biorefinery Symposium (2011ABBS), October 13-15, 2011, Bogor, Indonesia SN - 0360-3199 VL - 37 IS - 20 SP - 15288 EP - 15300 KW - Proton exchange membrane fuel cell; Startup and shutdown processes; Reverse current; Current distribution; Current mapping; Segmented fuel cell AB - Current distribution during the gas starvation and shutdown processes is investigated in a proton exchange membrane fuel cell with an active area of 184 cm². The cell features a segmented cathode current collector. The response characteristics of the segmented single cell under different degrees of hydrogen and air starvation are explored. The current responses of the segment cells at different positions under a dummy load in the shutdown process are reported for various operating conditions, such as different dummy loads, cell temperatures, and gas humidities under no back pressure. The results show that applying a dummy load during the cell shutdown process can quickly reduce the cell potential and thereby avoid the performance degradation caused by high potentials. The currents of all the segment cells decrease with time, but the rate of decrease varies with the segment cell positions. The rate for the segment cells near the gas outlet is much higher than that of the segment cells near the gas inlet. The current of the segment cells decreases much more quickly at a lower gas humidity and high temperature. This study provides insights in the development of mitigation strategies for the degradation caused by starvation and shutdown process. DA - 2012/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a7eb95e8-1e65-4e25-941b-8e94c6091588 ER - TY - JOUR TI - Phylogroup and lpfA influence epithelial invasion by mastitis associated Escherichia coli DO - 10.1016/j.vetmic.2012.03.033 AU - Dogan, Belgin AU - Rishniw, Mark AU - Bruant, Guillaume AU - Harel, Josee AU - Schukken, Ynte H. AU - Simpson, Kenneth W. T2 - Veterinary Microbiology SN - 03781135 VL - 159 IS - 1-2 SP - 163 EP - 170 KW - Escherichia coli; Mastitis; Virulence; Long polar fimbriae; Phylogroup AB - Escherichia coli infection is one of the most common causes of bovine mastitis in well managed dairies. Although E. coli infections are usually transient, E. coli can also cause persistent intramammary infections. We sought to determine whether E. coli isolates recovered from either transient or persistent intramammary infections differed both genetically and in their ability to invade mammary epithelial cells. E. coli isolates from transient (ECtrans, n = 16) and persistent (ECpers, n = 12) mastitis cases were compared for differences in overall genotype, virulence genes, serotype, phylogroup (A, B1, B2, D), and invasion of bovine mammary epithelial cells, MAC-T by microarray analysis, suppressive subtractive hybridization, PCR and gentamicin protection assays. ECtrans and ECpers were diverse in overall genotype and serotype, and were predominantly of phylogroups A and B1. Both ECtrans and ECpers contained genes encoding type II, IV and VI secretion systems, long polar fimbriae (lpfA) and iron acquisition, and lacked genes associated with virulence in diarrheagenic E. coli. ECtrans had fewer virulence genes than ECpers (p < 0.05), but no individual virulence genes were unique to either group. In phylogroup A, ECpers were more invasive than ECtrans (p < 0.05), but no difference was observed between them in phylogroup B1. Enhanced epithelial cell invasion was associated with lpfA (p < 0.05). Our findings indicate that a genetically diverse group of E. coli is associated with transient and persistent mastitis. We did not identify a set of bacterial genes to account for phenotypic differences. However, we found that mastitis phenotype, phylogroup and presence of lpfA were associated with the ability to invade cultured bovine mammary epithelial cells. DA - 2012/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9046aafe-1627-4944-a4cf-26d67854f731 ER - TY - JOUR TI - An atypical biotype I Actinobacillus pleuropneumoniae serotype 13 is present in North America DO - 10.1016/j.vetmic.2011.11.024 AU - Perry, Malcolm B. AU - Angen, Øystein AU - Maclean, Leann L. AU - Lacouture, Sonia AU - Kokotovic, Branko AU - Gottschalk, Marcelo T2 - Veterinary Microbiology SN - 03781135 VL - 156 IS - 3-4 SP - 403 EP - 410 KW - Actinobacillus pleuropneumoniae; Biotype 1; Serotype 13 capsular polysaccharide; Serotype 10 lipopolysaccharide AB - Atypical Actinobacillus pleuropneumoniae serotype 13 strains present in North America are described here for the first time. Different from serotype 13 strains described in Europe, North America strains are biotype I and antigenically related to both, serotypes 13 and 10. Chemical and structural analysis of the capsular polysaccharide (CPS) and lipopolysaccharide (LPS) of a representative strain revealed that the CPS is almost identical to that of the reference strain of serotype 13, having a slightly higher degree of glycose O-acetylation. However, it produces an O-PS within the LPS antigenically and structurally identical with that of the reference strain of A. pleuropneumoniae serotype 10. The O-PS was characterized as a homopolymer of 1,2 linked β-d-galactofuranosyl residues, a structure unrelated to that of the O-PS produced by the reference strain of serotype 13. Strains from Canada and United States are antigenically, phenotypically and genotypically similar. Animals infected by one of these strains induced antibodies that were detected by a LPS-based ELISA diagnostic test using either the homologous antigen or that of serotype 10. Based on the LPS and toxin profile, these strains might be misidentified as A. pleuropneumoniae serotype 10. DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 178236f3-a2f6-4bcd-9e48-56a73b834688 ER - TY - JOUR TI - Diagnosis of contamination introduced by ammonia at the cathode in a polymer electrolyte membrane fuel cell DO - 10.1016/j.ijhydene.2012.05.125 AU - Yuan, Xiao-Zi AU - Li, Hui AU - Yu, Yi AU - Jiang, Max AU - Qian, Weimin AU - Zhang, Shengsheng AU - Wang, Haijiang AU - Wessel, Silvia AU - Cheng, Tommy T. H. T2 - International Journal of Hydrogen Energy T3 - 12th CHEC, October 14-17, 2011, Wuhan, China SN - 0360-3199 VL - 37 IS - 17 SP - 12464 EP - 12473 KW - PEM fuel cell; Ammonia; Contamination; Diagnosis AB - Contamination introduced by impurities from feed streams can impact polymer electrolyte membrane fuel cell performance dramatically. The presence of unwanted trace species, such as CO, H2S, and NH3, can adversely affect the function of a fuel cell. It has been reported that the major impact of CO and H2S contamination on fuel cell performance is kinetic, while the effect of NH3 contamination is speculated to be mainly membrane conductivity reduction. In this paper, the effect of NH3 contamination from the cathode side was investigated. The mechanisms of NH3 contamination were diagnosed based on degradation tests using electrochemical impedance spectroscopy and cyclic voltammetry. The contamination factors investigated included ammonia concentration, operating current, temperature, and relative humidity. The results show that the severity of the adverse effect caused by ammonia contamination was enhanced by increased ammonia concentration, decreased operating temperature, and decreased relative humidity. The performance decay induced by ammonia is attributable to reduced membrane/ionomer conductivity and ammonia adsorption on the catalyst surface, which blocks the active sites and hinders mass transfer. DA - 2012/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1fca6c6c-5d00-42dc-b1ec-47762cac6648 ER - TY - JOUR TI - Effects of flow field design on the performance of a PEM fuel cell with metal foam as the flow distributor DO - 10.1016/j.ijhydene.2012.05.008 AU - Tsai, Bin-Tsang AU - Tseng, Chung-Jen AU - Liu, Zhong-Sheng AU - Wang, Chih-Hao AU - Lee, Chun-I AU - Yang, Chang-Chung AU - Lo, Shih-Kun T2 - International Journal of Hydrogen Energy SN - 0360-3199 VL - 37 IS - 17 SP - 13060 EP - 13066 KW - Proton exchange membrane fuel cell; Metal foam; Flow distributor; AC impedance AB - In this work, we report the improvements made on the PEM fuel cell with metal foam as the flow distributor. The comparison in polarization curve is made between the PEM unit cell with different metal foam flow field designs and the PEM unit cell with graphite bipolar plate as flow distributor. The experimental results show that after using improved metal foam flow field designs, the fuel cell's performance increases. Our results show that, in the PEM unit cell with single zone metal foam, the convection is weak at side corners. Dividing the metal foam into multiple regions and using multiple inlets effectively improves gas distribution. AC impedance measurement was also performed to study impedance characteristics. The Nyquist and Bode plots confirmed that Ohmic resistance, activation resistance, and mass transfer resistance of metal foam fuel cell are all smaller than that of conventional PEM unit cell. DA - 2012/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4dfc1a07-b53f-476e-90df-b52d2f56f1f7 ER - TY - JOUR TI - Fine specificity and cross-reactions of monoclonal antibodies to group B streptococcal capsular polysaccharide type III DO - 10.1016/j.vaccine.2012.05.006 AU - Pincus, Seth H. AU - Moran, Emily AU - Maresh, Grace AU - Jennings, Harold J. AU - Pritchard, David G. AU - Egan, Marianne L. AU - Blixt, Ola T2 - Vaccine SN - 0264410X VL - 30 IS - 32 SP - 4849 EP - 4858 KW - CPSIII, group B streptococcal capsular polysaccharide type III; GBS, group B streptococci; GD3, glycan Neu5Ac(α2-8)Neu5Ac(α2-3)Gal (β1-4)Glc; GT3, glycan Neu5Ac(α2-8)Neu5Ac (α2-8)Neu5Ac(-α2-3)Gal(β1-4)Glc; PAA, polyacrylamide AB - Group B streptococcus (GBS) is a major cause of neonatal sepsis and meningitis. Despite aggressive campaigns using antenatal prophylactic antibiotic therapy, infections continue. Developing an effective maternal vaccine is a public health priority. Antibody (Ab) to the capsular polysaccharide (CPS) is considered the dominant “protective” immune mediator. Here we study the fine specificity and potential host reactivity of a panel of well-characterized murine monoclonal Abs against the type III CPS by examining the binding of the Abs to intact and neuraminidase-digested GBS, purified CPS, synthetic carbohydrate structures, and cells. The results showed marked differences in the fine specificity among these mAbs to a single carbohydrate structure. Cross-reactions with synthetic GD3 and GT3 carbohydrates, representing structures found on surfaces of neural and developing cells, were demonstrated using carbohydrate array technology. The anti-CPSIII mAbs did not react with cells expressing GD3 and GT3, nor did mAbs specific for the host carbohydrates cross-react with GBS, raising questions about the physiological relevance of this cross-reaction. But in the process of these investigations, we serendipitously demonstrated cross-reactions of some anti-CPSIII mAbs with antigens, likely carbohydrates, found on human leukocytes. These studies suggest caution in the development of a maternal vaccine to prevent infection by this important human pathogen. DA - 2012/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 083ff8ce-4b78-4a7d-8da8-2d88412eaa68 ER - TY - JOUR TI - Microstructural evolution during low temperature sorption cycling of Mg-AlTi multilayer nanocomposites DO - 10.1016/j.ijhydene.2011.11.113 AU - Zahiri, Ramin AU - Zahiri, Beniamin AU - Kubis, Alan AU - Kalisvaart, Peter AU - Amirkhiz, Babak Shalchi AU - Mitlin, David T2 - International Journal of Hydrogen Energy SN - 0360-3199 VL - 37 IS - 5 SP - 4215 EP - 4226 KW - Magnesium hydride; Catalyst dispersion; Z-contrast STEM; Cycling stability; Sputtering; Multilayers; Activation AB - We studied the hydrogen storage behavior of sputtered Mg-AlTi multilayers where nanometric Mg or Mg–Al–Ti layers were confined by 2 nm thick layers of AlTi. By decreasing the thickness of Mg layers, we were able to achieve 5.1 wt.% H capacity without significant degradation in over 200 cycles at 473 K. However, for the samples with pure Mg layers degradation eventually occurred at higher cycle numbers. In multilayers of 34 nm thick Mg degradation was followed by disintegration of the films into sponge-like flakes. Alloying Mg layers with Al and Ti through cosputtering improved the performance of the multilayer composites. Through cycling, Al and Ti segregated out of Mg matrix and formed a nanocrystalline/amorphous AlTi phase as observed by X-ray diffraction and electron microscopy. This improved resistance of the microstructure against coarsening while a well dispersion of AlTi particles was achieved. Moreover, the stability of multilayers enhanced to an extent that they not only preserved their physical integrity, also did they maintain their superior kinetics up to over 250 cycles. Pressure - composition isotherms showed no significance change in thermodynamics of MgH2 formation. DA - 2012/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ce7300e5-b6a5-4146-a9e9-6c1873c8e56b ER - TY - JOUR TI - Design and immunological properties of Helicobacter pylori glycoconjugates based on a truncated lipopolysaccharide lacking Lewis antigen and comprising an α-1,6-glucan chain DO - 10.1016/j.vaccine.2012.04.035 AU - Altman, Eleonora AU - Chandan, Vandana AU - Harrison, Blair A. AU - Veloso-pita, Roberto AU - Li, Jianjun AU - Kuolee, Rhonda AU - Chen, Wangxue AU - Vérez-bencomo, Vicente T2 - Vaccine SN - 0264410X VL - 30 IS - 50 SP - 7332 EP - 7341 KW - Helicobacter pylori; Conjugate vaccine; LPS; Bactericidal assay AB - To investigate the vaccine potential of H. pylori lipopolysaccharide (LPS), truncated LPS of H. pylori strain 26695 HP0826::Kan lacking O-chain polysaccharide and comprising an extended α-1,6-linked glucan chain was conjugated to tetanus toxoid (TT) or bovine serum albumin (BSA). Two approaches were used for delipidation or partial delipidation of H. pylori LPS: (1) mild hydrolysis resulting in delipidated LPS (dLPS) and (2) treatment with anhydrous hydrazine resulting in removal of O-linked fatty acids (LPS-OH). Both LPS-OH and dLPS were covalently linked through a 2-keto-3-deoxy-octulosonic acid (Kdo) residue to a diamino group-containing spacer, followed by conjugation to thiolated TT or BSA to give conjugates LPS-OH-TT, dLPS-BSA and dLPS-TT, respectively. The LPS-OH-TT, dLPS-BSA and dLPS-TT conjugates were immunogenic in both rabbits and mice, inducing strong and specific IgG responses against homologous and heterologous strains of H. pylori. Moreover, the rabbit post-immune sera showed cross-reactivity against clinical isolates of H. pylori in a whole-cell indirect ELISA, which was further confirmed by indirect immunofluorescent microscopy. A tenfold stronger IgG immune response to the immunizing antigen was generated in mice and rabbits that received dLPS-containing conjugate. The post-immune sera of rabbits immunized with LPS-OH-TT, dLPS-BSA or dLPS-TT displayed significant bactericidal activity against mutant and wild-type α-1,6-glucan-expressing strains and selected clinical isolates of H. pylori. Finally, partial protection against H. pylori challenge was demonstrated in mice vaccinated with dLPS-TT conjugate adjuvanted with cholera toxin. In summary, this study shows that glycoconjugates based on delipidated or partially delipidated LPS from H. pylori 26695 HP0826::Kan mutant induce broadly cross-reactive functional antibodies in immunized animals and should be considered for further vaccine development and testing. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f0ad53d5-8382-441b-860e-c3fd682e5b11 ER - TY - JOUR TI - Characterization of antimicrobial resistance and virulence genes in Enterococcus spp. isolated from retail meats in Alberta, Canada DO - 10.1016/j.ijfoodmicro.2012.03.026 AU - Aslam, Mueen AU - Diarra, Moussa S. AU - Checkley, Sylvia AU - Bohaychuk, Valerie AU - Masson, Luke T2 - International Journal of Food Microbiology SN - 0168-1605 VL - 156 IS - 3 SP - 222 EP - 230 KW - Antimicrobial resistance; Resistance genes; Virulence genes; Enterococcus spp. retail meats AB - The objective of this study was to characterize antimicrobial resistance (AMR) and virulence genotypes of Enterococcus spp. particularly Enterococcus faecalis isolated from retail meats purchased (2007–2008) in Alberta, Canada. Unconditional statistical associations between AMR pheno- and genotypes and virulence genotypes were determined. A total of 532 enterococci comprising one isolate from each positive sample were analyzed for antimicrobial susceptibility. A customized enterococcal microarray was used for species identification and the detection of AMR and virulence genes. E. faecalis was found in > 94% of poultry samples and in about 73% of beef and 86% of pork samples. Enterococcus faecium was not found in turkey meat and its prevalence was 2% in beef and pork and 4% in chicken samples. None of the enterococci isolates were resistant to the clinically important drugs ciprofloxacin, daptomycin, linezolid and vancomycin. Multiresistance (≥ 3 antimicrobials) was more common in E. faecalis (91%) isolated from chicken and turkey (91%) than those isolated from beef (14%) or pork (45%). Resistance to aminoglycosides was also noted at varying degrees. The most common resistance genes found in E. faecalis were aminoglycosides (aac, aphA3, aadE, sat4, aadA), macrolides (ermB, ermA), tetracyclines (tetM, tetL, tetO), streptogramin (vatE), bacitracin (bcrR) and lincosamide (linB). Virulence genes expressing aggregation substances (agg) and cytolysin (cylA, cylB, cylL, cylM) were found more frequently in poultry E. faecalis and were unconditionally associated with tetM, linB and bcrR resistance genes. Other virulence genes coding for adhesion (ace, efaAfs), gelatinase (gelE) were also found in the majority of E. faecalis. Significant statistical associations were found between resistance and virulence genotypes, suggesting their possible physical link on a common genetic element. This study underscores the importance of E. faecalis as a reservoir of resistance and virulence genes and their potential transfer to humans through consumption of contaminated undercooked meat. DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fca88680-51c6-488a-9213-3f0762316e75 ER - TY - JOUR TI - Trophic transfer of brevetoxins to the benthic macrofaunal community during a bloom of the harmful dinoflagellate Karenia brevis in Sarasota Bay, Florida DO - 10.1016/j.hal.2012.01.001 AU - Bricelj, V. M. AU - Haubois, A.-G. AU - Sengco, M. R. AU - Pierce, R. H. AU - Culter, J. K. AU - Anderson, D. M. T2 - Harmful Algae SN - 1568-9883 VL - 16 SP - 27 EP - 34 KW - Karenia brevis; Brevetoxins; Benthic trophic transfer AB - Harmful algal blooms can cause mass mortalities of top predators such as fish, marine mammals and seabirds but the food web transfer from toxic phytoplankton to these organisms has not been fully elucidated. Macrobenthic invertebrates in coastal waters, including bivalve suspension- and deposit-feeders, carnivorous gastropods, deposit-feeding amphipods and polychaetes, are a major food source for a wide variety of predators and can thus play a critical role in the trophic transfer of algal toxins to higher trophic levels. The objective of this study was to investigate toxin accumulation in transplanted juvenile hard clams, Mercenaria mercenaria, a species naturally occurring in the region, and in various macrobenthic functional groups from Florida coastal waters during a natural bloom of the dinoflagellate, Karenia brevis, a producer of brevetoxins. Bloom concentrations in the water column ranged from 100 to 1200 cells ml−¹ over the course of the experiment. This study revealed that these lipophilic toxins can be rapidly accumulated by both suspension- and deposit-feeding benthos, especially bivalve molluscs [1.9–2.8 μg PbTx-3 eq (g wet weight)−¹]. Transplanted M. mercenaria rapidly accumulated toxins from the water column attaining ∼0.5 μg PbTx-3 eq (g wet tissue)−¹ after only 4 h-exposure to the K. brevis bloom and a maximum value of 1.5 ± 0.2 μg PbTx-3 eq (g wet tissue)−¹ after 72 h. Relatively high brevetoxin concentrations were also measured in co-occurring benthic carnivorous gastropods [1–2.6 μg PbTx-3 eq (g wet weight, WW)−¹]. Mean toxin concentrations in polychaetes and crustaceans varied in the range ∼0.04–0.2 μg PbTx-3 eq (g WW)−¹ over the study period, and thus were typically lower than in molluscs. This study demonstrated in situ toxin accumulation by benthic primary and secondary consumers during a natural Florida red tide. Accumulation by primary consumers may be highly variable in space and time (as shown in bivalves from the natural benthic community) and among taxonomic groups. Toxin transfer further up the food web will thus depend on the toxin level accumulated in prey, the number of pathways from which the predator may accumulate toxins and on possible biological magnification of lipophilic toxins. Overall, this study revealed qualitatively and quantitatively that benthic consumers of a number of taxa can serve as vectors for transporting brevetoxins within the food web. DA - 2012/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7f58b1ae-29c9-4eb8-b630-3217eb625311 ER - TY - JOUR TI - A quality of service (QoS)-aware execution plan selection approach for a service composition process DO - 10.1016/j.future.2011.08.017 AU - Liu, Min AU - Wang, Mingrui AU - Shen, Weiming AU - Luo, Nan AU - Yan, Junwei T2 - Future Generation Computer Systems SN - 0167-739X VL - 28 IS - 7 SP - 1080 EP - 1089 KW - QoS; Service composition; Flexible constraint; Web services AB - The quality of service (QoS)-aware service composition (QSC) problem is to find an execution plan of a service composition process which can ensure that the quality of service meets given user requirements. This paper proposes a branch and bound for execution plan selection (BB4EPS) algorithm to solve the QSC problem. In the proposed BB4EPS algorithm, a universal QoS model is used to evaluate the QoS parameters for service composition, and the QSC problem is modeled as an extended flexible constraint satisfaction framework, in which the utility function is applied to build the objective function. Numerical simulation results show that the proposed algorithm is feasible and effective. DA - 2012/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3ba0d588-96cd-48c2-899c-1e247a88cd0f ER - TY - JOUR TI - Performance in fire of FRP-strengthened and insulated reinforced concrete columns DO - 10.1016/j.firesaf.2012.08.006 AU - Cree, D. AU - Chowdhury, E. U. AU - Green, M. F. AU - Bisby, L. A. AU - Bénichou, N. T2 - Fire Safety Journal SN - 0379-7112 VL - 54 SP - 86 EP - 95 KW - Fire test; FRP; Insulation; Reinforced concrete column; High temperature; Full-scale AB - This research investigates the fire performance of one circular and one square reinforced concrete column strengthened with a fibre reinforced polymer (FRP) wrap and covered with a unique supplemental fire protection system. An experimental full-scale fire resistance test was conducted at the National Research Council of Canada. The insulated and strengthened FRP wrapped columns were exposed to the ULC-S101 standard fire and both columns obtained fire endurance ratings of over 4 h. Details of the fire endurance experiment on both columns are described in this paper. Additionally, numerical models developed specifically for circular and square columns are validated against the experimental results. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2548007c-9a57-4e43-9cf7-f5cb956bff0e ER - TY - JOUR TI - Trajectories of changes over twelve years in the health status of Canadians from late middle age DO - 10.1016/j.exger.2012.06.015 AU - Mitnitski, A. AU - Song, X. AU - Rockwood, K. T2 - Experimental Gerontology SN - 0531-5565 VL - 47 IS - 12 SP - 893 EP - 899 KW - Health status; Deficit accumulation; Frailty index; Mortality; Stochastic process; Aging AB - Aging in a given individual can be characterized by the number of deficits (symptoms, signs, laboratory abnormalities, disabilities) that they accumulate. The number of accumulated deficits, more than their nature, well characterizes health status in individuals — the proportion of deficits present in an individual to deficits considered is known as a frailty index. While on average deficits accumulate with age, individual trajectories in the number of deficits is highly dynamic. Transitions in the number of deficits over a fixed time interval can be represented by the Poisson law, with the Poisson mean dependent on the deficit numbers at baseline. Here we present an extension of the model to make possible predictions for any given time period. Using data from the Canadian National Population Health Survey of people aged 55 and over (n = 4330), followed during 7 cycles being the baseline and 6 cycles of follow-up every 2 years, we found that the transition in the number of deficits during any time period can be approximated using a time dependent Poisson distribution with the Poisson mean tending to decelerate over time, according to square-root-of-time kinetics characteristic for stochastic processes (e.g. diffusion, Brownian motion ) while the probability of death shows a pattern of time acceleration with a high degree of precision, “explaining” over 98% of variance. The model predicts a variety of changes in health status including the possibility of health improvement indicating the repair/remodeling abilities of the organism. The model is valuable for estimating how changes in health can influence mortality across the life course from late middle age. DA - 2012/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ee4b24e7-6ef0-4fed-b980-bd041931643e ER - TY - JOUR TI - The development of conductive carbon nanotube network in polypropylene-based composites during simultaneous biaxial stretching DO - 10.1016/j.eurpolymj.2012.03.005 AU - Shen, Jiabin AU - Champagne, Michel F. AU - Gendron, Richard AU - Guo, Shaoyun T2 - European Polymer Journal SN - 0014-3057 VL - 48 IS - 5 SP - 930 EP - 939 KW - Biaxial stretching; Polymer-matrix composites; Carbon nanotube; Electrical properties AB - The development of electronic conducting networks during the simultaneous biaxial stretching of isotactic polypropylene/carbon nanotube (iPP/CNT) composites was investigated. During the stretching process, the electrical resistivity of the composites was found to be very sensitive to the draw ratios. This was especially true at CNT concentration close to the percolation threshold, ca. 2.2 vol.%. The resistivity–draw ratio dependence was divided into two stages. In the first stage, the stretching was taken by the amorphous zones and only led to the enlargement of the distance between CNT aggregates. This resulted in the breaking of the conductive network and, consequently, a sharp increase in resistivity. As the turning point was approached, individual nanotubes started to disentangle from CNT aggregates. Meanwhile, the resistivity of the stretched films was dramatically decreased by 7 orders of magnitude, indicating a rebuilding of the conducting network during the biaxial stretching process. DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5ccdff83-691e-4038-aa0f-f7a0157a0d2e ER - TY - JOUR TI - BALB/c mice, but not C57BL/6 mice immunized with a ΔclpB mutant of Francisella tularensis subspecies tularensis are protected against respiratory challenge with wild-type bacteria: Association of protection with post-vaccination and post-challenge immune responses DO - 10.1016/j.vaccine.2012.03.036 AU - Twine, Susan AU - Shen, Hua AU - Harris, Gregory AU - Chen, Wangxue AU - Sjostedt, Anders AU - Ryden, Patrik AU - Conlan, Wayne T2 - Vaccine SN - 0264410X VL - 30 IS - 24 SP - 3634 EP - 3645 KW - Francisella tularensis; Vaccine; Cytokines: Immunoproteomics AB - Francisella tularensis subspecies tularensis is highly virulent for humans especially when it is inhaled. Therefore, it has the potential to be used as a biothreat agent. Vaccines against F. tularensis will need to be approved in accordance with the FDA Animal Rule. This will require identification of robust correlates of protection in experimental animals and the demonstration that similar immune responses are generated in vaccinated humans. Towards this goal, we have developed an experimental live vaccine strain by deleting the gene, clpB, encoding a heat shock protein from virulent subsp. tularensis strain, SCHU S4. SCHU S4ΔclpB administered intradermally protects BALB/c, but not C57BL/6 mice from subsequent respiratory challenge with wildtype SCHU S4. A comparison of post-vaccination and post-challenge immune responses in these two mouse strains shows an association between several antibody and cytokine responses and protection. In particular, elevated IFNγ levels in the skin 2 days after vaccination, sero-conversion to hypothetical membrane protein FTT_1778c, and to 30S ribosomal protein S1 (FTT_0183c) of F. tularensis after 30 days of vaccination, and elevated levels of pulmonary IL-17 on day 7 after respiratory challenge with SCHU S4 were all associated with protection. DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6570378e-d4ee-4506-81ac-b7984e408c08 ER - TY - JOUR TI - Ultrasound-enhanced monoclonal antibody production DO - 10.1016/j.ultrasmedbio.2012.06.008 AU - Xing, James Z. AU - Yang, Xiaoyan AU - Xu, Peng AU - Ang, Woon T. AU - Chen, Jie T2 - Ultrasound in Medicine & Biology SN - 03015629 VL - 38 IS - 11 SP - 1949 EP - 1957 KW - Ultrasound-enhanced drug production; Low-intensity pulsed ultrasound; Value-added biotechnology; Monoclonal antibody production; Hybridoma AB - With the rapidly growing demand for monoclonal antibody (mAb)–based products, new technologies are urgently needed to increase mAb production while reducing manufacturing costs. To solve this problem, we report our research findings of using low-intensity pulsed ultrasound (LIPUS) to enhance mAb production. LIPUS with frequency of 1.5 MHz and pulse repetition frequency of 1 kHz, as well as duty cycle of 20%, was used to stimulate hybridoma cells to enhance the production of mAb, anti-CD4 (hybridoma GK1.5). The enzyme-linked immunosorbent assay results show a 60.42 ± 7.63% increase of mAb expression in hybridoma cells. The evidence of structural changes of the cellular outer membrane in both transmission electron microscopy and scanning electron microscopy images and the more than 20% lactate dehydrogenase release indicates that the increased mAb production is related to the increased cell permeability induced by LIPUS. This value-added ultrasound technology provides a potential cost-effective solution for pharmaceutical companies to manufacture mAb-based drugs. The technology, in turn, can reduce the drug manufacturing costs and decrease health care spending. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4c825837-0d01-4be2-9888-4e25d90f5559 ER - TY - JOUR TI - Re-assessment of resistance of cast iron pipes subjected to vertical loads and internal pressure DO - 10.1016/j.engstruct.2012.06.019 AU - Rajani, Balvant AU - Abdel-Akher, Ahmed T2 - Engineering Structures SN - 0141-0296 VL - 45 SP - 192 EP - 212 KW - Cast iron; Corrosion; Deteriorated pipe; Vertical loads; Internal water pressure; Factor of safety AB - Longitudinal fracture is one predominant observed failure mode in large diameter cast iron pipes installed between 1850 and early 1960s. Some of these failures occur where there is evidence of some corrosion activity. This paper addresses three specific issues, namely, (1) review of expected loads, i.e., internal pressure, earth loads, traffic loads, (2) estimated pipe failure load (pipe resistance), and (3) estimated structural factor of safety. The second and third issues can be equally applicable to non-deteriorated and deteriorated pipes. The procedures described in this paper were motivated by the need to purposefully use the information derived from pipe inspection to assess the margin of safety of deteriorated large diameter cast iron pipes. A mechanistic model that accounts for cast iron material non-linearity is described. The model is validated using data obtained from experimental tests conducted in the mid 1930s on undamaged (new) pipes. The model is subsequently extended to permit the analysis of pipes with corrosion pits or corroded areas. Reliability analysis using Monte Carlo simulations is proposed to account for uncertainties in input data. Illustrative analyses of 16″ and 48″ diameter pipes subjected to vertical loads and internal pressure showed that significantly high margins of safety exist in cast iron pipes with no damage (due to corrosion and or casting voids) while this margin of safety is meaningfully reduced in the presence of corrosion pits or corroded areas. The methodology described should enable engineers to realistically assess the pipe resistance capacity and hence the corresponding margin of safety of undamaged or damaged cast iron pipes encountered in current operational conditions. DA - 2012/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4d53ebdb-a919-4902-8439-18adc04a6d95 ER - TY - JOUR TI - Inelastic load distribution in multi-girder composite bridges DO - 10.1016/j.engstruct.2012.05.014 AU - Razaqpur, A. Ghani AU - Shedid, Marwan AU - Nofal, Mostafa T2 - Engineering Structures SN - 0141-0296 VL - 44 SP - 234 EP - 247 KW - Analysis; Bridge; Composite; Concrete; Finite element; Load distribution; Reinforced; Steel AB - To accurately assess the ultimate load capacity of concrete slab-steel girder bridges, the effects of concrete nonlinearity and steel yielding on the truck load distribution in simply supported composite bridges are investigated using the nonlinear finite element (FE) method. In this study, fifty cases are analyzed to investigate the effect of the aforementioned parameters as well as the effects of other parameters including longitudinal and transversal truck position, number of loaded lanes (2–4), bridge length (12–20 m) and width (8–16 m), number of girders (3–6), girder spacing (2–3.75 m), and slab thickness (175–275 mm). The moment in each girder, based on the nonlinear FE analysis, is used to obtain its Load Distribution Factor (LDF) at different load levels up to failure and is compared with the corresponding elastic LDF according to AASHTO LRFD specifications. The results show from zero to 54% increase in the internal girder LDF (average 32%), and from zero to 29% decrease in the external girder LDF (average 17%) as the bridge traverses from the elastic to the ultimate state. This redistribution can be advantageously used when evaluating the load carrying capacity of existing bridges. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 94f3d644-e99e-47d8-a6a0-229616e9fbcf ER - TY - JOUR TI - A fracture toughness model for brittle coating on ductile substrate under indentation loading DO - 10.1016/j.engfracmech.2011.11.018 AU - Demidova, N. V. AU - Wu, X. J. AU - Liu, R. T2 - Engineering Fracture Mechanics SN - 0013-7944 VL - 82 SP - 17 EP - 28 KW - Brittle coating; Ductile substrate; Indentation; Elliptical crack; Fracture toughness; Composite hardness; Interface correction factor AB - This paper presents an analytical fracture toughness model for brittle coating/ductile substrate systems. The model considers a well-developed radial/median crack of semi-elliptical shape in proximity of the coating/substrate interface. It incorporates three critical factors to correct Lawn et al.’s formalism for monolithic materials: (i) an elliptical crack shape factor introduced by adopting Borodachev’s solution for an elliptical crack under a concentrated force at the crack center, which represents the residual plastic component due to expansion of the plastic zone under indentation; (ii) an interface correction factor obtained by analyzing Noda et al.’s results for an elliptical crack near a bi-material interface, which expresses explicitly its dependence on the distance ratio, h/a, and Young’s modulus ratio, Es/Ec, and (iii) the composite system hardness incorporated in the formula to take into account the influence of the substrate material. Overall, the model shows a non-linear relationship between the radial crack length, c³/², and indentation load, P, for brittle coating on ductile substrate systems. A series of indentation experiments have been carried out on a WC/10Co/4Cr coating/1080 low carbon steel substrate system to validate the model. DA - 2012/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 087e7298-968c-4433-a454-9ae8b28396e7 ER - TY - JOUR TI - Field ion microscope evaluation of tungsten nanotip shape using He and Ne imaging gases DO - 10.1016/j.ultramic.2012.07.026 AU - Urban, Radovan AU - Wolkow, Robert A. AU - Pitters, Jason L. T2 - Ultramicroscopy SN - 03043991 VL - 122 SP - 60 EP - 64 KW - Nanotip; Field ion microscopy; Gas field ion source AB - Field ion microscopy (FIM) using neon imaging gas was used to evaluate a W(111) nanotip shape during a nitrogen assisted etching and evaporation process. Using appropriate etching parameters a narrow ring of atoms centered about the tip axis appears in a helium generated image. Etching of tungsten atoms continues exclusively on the outside of this well-defined ring. By replacing helium imaging gas with neon, normally inaccessible crystal structure of a tip apex is revealed. Comparison of the original W(111) tip (before etching) and partly etched tip shows no atomic changes at the tip apex revealing extraordinarily spatially selective etching properties of the etching process. This observation is an important step towards a detailed understanding of the nitrogen assisted etching and evaporation process and will lead to better control over atomically defined tip shapes. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b733ab84-2e5a-40a1-a62e-a989b45cec8f ER - TY - JOUR TI - A data-model-fusion prognostic framework for dynamic system state forecasting DO - 10.1016/j.engappai.2012.02.015 AU - Liu, J. AU - Wang, W. AU - Ma, F. AU - Yang, Y. B. AU - Yang, C. S. T2 - Engineering Applications of Artificial Intelligence SN - 0952-1976 VL - 25 IS - 4 SP - 814 EP - 823 KW - Nonlinear prediction; Fault diagnosis; Failure prognostics; Neural networks; Neural fuzzy systems; Remaining useful life prediction AB - A novel data-model-fusion prognostic framework is developed in this paper to improve the accuracy of system state long-horizon forecasting. This framework strategically integrates the strengths of the data-driven prognostic method and the model-based particle filtering approach in system state prediction while alleviating their limitations. In the proposed methodology, particle filtering is applied for system state estimation in parallel with parameter identification of the prediction model (with unknown parameters) based on Bayesian learning. Simultaneously, a data-driven predictor is employed to learn the system degradation pattern from history data so as to predict system evolution (or future measurements). An innovative feature of the proposed fusion prognostic framework is that the predicted measurements (with uncertainties) from the data-driven predictor will be properly managed and utilized by the particle filtering to further update the prediction model parameters, thereby enabling markedly better prognosis as well as improved forecasting transparency. As an application example, the developed fusion prognostic framework is employed to predict the remaining useful life of lithium ion batteries through electrochemical impedance spectroscopy tests. The investigation results demonstrate that the proposed fusion prognostic framework is an effective forecasting tool that can integrate the strengths of both the data-driven method and the particle filtering approach to achieve more accurate state forecasting. DA - 2012/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 99dd5e45-39fc-4d73-bc67-9c558457de54 ER - TY - JOUR TI - Electron beam deposited Nb-doped TiO2 toward nanostructured transparent conductive thin films DO - 10.1016/j.tsf.2012.10.075 AU - Tucker, Ryan T. AU - Beckers, Nicole A. AU - Fleischauer, Michael D. AU - Brett, Michael J. T2 - Thin Solid Films SN - 00406090 VL - 525 SP - 28 EP - 34 KW - Nb-doped TiO2; Transparent conducting oxides; Doped oxides; Evaporation; Glancing angle deposition; Sol–gel; Thin film AB - Nb-doped TiO2 (TNO) has been widely explored as an alternative transparent conductor. TNO thin films have been fabricated by various deposition methods, and here we demonstrate fabrication by evaporation of sol–gel synthesized TNO source material. A range of NbxTi1 − xO2 (x = 0, 0.03, 0.06, 0.12, 0.24) compositions were synthesized, pressed into pellets, and deposited as thin films via electron beam evaporation. The thin films were characterized for composition by energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy and for crystallinity by X-ray diffraction for the different Nb contents explored. Transparency, conductivity, and Haacke transparent conductor figure of merit values are reported for the evaporated TNO films as a function of Nb content, substrate heating temperature, and post deposition annealing conditions. Glancing angle deposition (GLAD) is used to demonstrate nanostructuring of evaporated TNO based on physical shadowing. Nanostructured GLAD TNO films of increased morphological complexity can be produced using this method, and could lead to unique transparent conductor device architectures. DA - 2012/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d53204fa-1b48-47ee-b919-370cafb37189 ER - TY - JOUR TI - Goniocolorimetric study of aluminum oxide films deposited by atomic layer deposition DO - 10.1016/j.tsf.2011.10.016 AU - Gordon, Peter G. AU - Baribeau, Réjean AU - Barry, Seán T. T2 - Thin Solid Films SN - 00406090 VL - 520 IS - 7 SP - 2943 EP - 2948 KW - Atomic layer deposition; Interference color; Goniocolorimetry; Chroma and hue AB - The interference colors resulting from thin films of Al2O3 deposited by atomic layer deposition (ALD) on silicon have been rigorously analyzed using a recently developed robotic gonioreflectometer. A series of eleven increasingly thick films was deposited, up to 1613 Å, and their reflectance values obtained for the visible spectrum. A comparison of these values with the predictions of computer simulations employing Fresnel equations has revealed that while there was generally good agreement between predicted and measured spectra, there are some spectral regions that exhibit large deviations from predicted reflectances, typically at near-normal measurement angles and shorter wavelengths. The effect of these discrepancies on color appearance was investigated in the CIE L*a*b* color space for the daylight illuminant D65. Large iridescence is both predicted and measured for most film thicknesses. Chroma and hue differences as large as 20 CIELAB units between the predicted and the measured color centers were obtained. Simulation also predicts larger iridescence than what is actually measured. A likely cause for the observed discrepancies is that the dielectric constants of the ALD films deviate from the literature values for the bulk material. DA - 2012/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 228a1c25-f926-4b57-a253-bb2ecccfdcef ER - TY - JOUR TI - Activity-based protein profiling of host–virus interactions DO - 10.1016/j.tibtech.2011.08.001 AU - Blais, David R. AU - Nasheri, Neda AU - Mckay, Craig S. AU - Legault, Marc C.B. AU - Pezacki, John paul T2 - Trends in Biotechnology SN - 01677799 VL - 30 IS - 2 SP - 89 EP - 99 AB - Virologists have benefited from large-scale profiling methods to discover new host–virus interactions and to learn about the mechanisms of pathogenesis. One such technique, referred to as activity-based protein profiling (ABPP), uses active site-directed probes to monitor the functional state of enzymes, taking into account post-translational interactions and modifications. ABPP gives insight into the catalytic activity of enzyme families that does not necessarily correlate with protein abundance. ABPP has been used to investigate several viruses and their interactions with their hosts. Differential enzymatic activity induced by viruses has been monitored using ABPP. In this review, we present recent advances and trends involving the use of ABPP methods in understanding host–virus interactions and in identifying novel targets for diagnostic and therapeutic applications. DA - 2012/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 14548caf-13f1-4fdd-a8b0-32e9cc9430d1 ER - TY - JOUR TI - Intramolecular cyclization and subsequent rearrangements of alkyne-tethered N-heterocyclic carbenes DO - 10.1016/j.tetlet.2012.08.038 AU - Legault, Marc C.B. AU - Mckay, Craig S. AU - Moran, Joseph AU - Lafreniere, Matthew A. AU - Pezacki, John paul T2 - Tetrahedron Letters SN - 00404039 VL - 53 IS - 42 SP - 5663 EP - 5666 KW - N-heterocyclic carbenes; Intramolecular cyclization; Diels–Alder cycloaddition AB - Alkyne-tethered imidazole and 1,2,4-triazole-based N-heterocyclic carbene precursors have been prepared and studies of the intramolecular reactions of carbenes are performed. Products consistent with intramolecular cyclizations and subsequent rearrangements were observed. Mechanistic studies using crossover experiments showed that the products did arise from intramolecular carbene additions. The reactions are proposed to go through vinylogous diaminocarbene intermediates similar to vinylogous dialkoxycarbenes formed during Boger cycloaddition reactions. Imidazole substituted dienes were observed to be the major products of tandem cyclization and elimination reactions that were observed for imidazole-based N-heterocyclic carbenes. DA - 2012/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 332a1863-5527-4e37-ad03-6e454a58fc74 ER - TY - JOUR TI - A PEM fuel cell with metal foam as flow distributor DO - 10.1016/j.enconman.2012.03.018 AU - Tseng, Chung-Jen AU - Tsai, Bin Tsang AU - Liu, Zhong-Sheng AU - Cheng, Tien-Chun AU - Chang, Wen-Chen AU - Lo, Shih-Kun T2 - Energy Conversion and Management SN - 0196-8904 VL - 62 SP - 14 EP - 21 KW - PEM fuel cell; Metal foam; Flow distributor; Mass transport AB - In this work, we report our experimental results of the PEM fuel cell with metal foam as flow distributor. These experimental results show the characteristics of the PEM fuel cell with the metal foam as flow distributor and extend our understanding of the relation between cell performance and mass transport properties into a region of parameters that the conventional PEM unit cell cannot provide. The comparison in polarization curve is made between the PEM unit cell with different metal-foam properties and the PEM unit cell with graphite flow channel plate as flow distributor. The experimental results show that the PEM fuel cell with metal foam as flow distributor possesses some unique characteristics compared with the conventional PEM unit cell with flow channel plate as flow distributor. The unique characteristics are listed in this paper with our preliminary analysis. Due to the high porosity of metal-foam (as high as 95%) plus convective flow through the metal-foam, mass transport limitation phenomenon is not as pronounced as in the case of conventional PEM unit cell with flow channel plate as flow distributor. Another interesting phenomenon is that electrical conductivity of metal-foam plays a significant role in performance, which is seldom the case in the conventional PEM unit cell with flow channel plate as flow distributor. Although there are several technical challenges to be overcome for the current form of metal-foam to replace flow channel plates, the unique mass-transport properties of metal foam plus its light weight are very attractive. DA - 2012/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 56963658-b6eb-481b-b0b1-20e4aca4d0fc ER - TY - JOUR TI - A novel methodology for knowledge discovery through mining associations between building operational data DO - 10.1016/j.enbuild.2011.12.018 AU - Yu, Zhun (Jerry) AU - Haghighat, Fariborz AU - Fung, Benjamin C. M. AU - Zhou, Liang T2 - Energy and Buildings SN - 0378-7788 VL - 47 SP - 430 EP - 440 KW - Data mining; Association; Correlation; Knowledge discovery; Building operational data; Energy conservation; Influencing factors AB - Nowadays, vast amounts of data on building operation and management have been collected and stored. However, the data is rarely translated into useful knowledge about building energy performance improvement, due mainly to its extreme complexity and a lack of effective data analysis techniques. This paper reports the development of a new methodology for examining all associations and correlations between building operational data, thereby discovering useful knowledge about energy conservation. The method is based on a basic data mining technique (association rule mining). To take full advantage of building operational data, both daily and annual time periods should be mined. Moreover, data from two different years should be mined, and the obtained associations and correlations in the two years should be compared. In order to demonstrate the applicability of the proposed method, the method was applied to the operational data of the air-conditioning system in a building located in Montreal. The results show energy waste in the air-conditioning system as well as equipment faults. A low/no cost strategy for saving energy in the system operation was also proposed. The results obtained could help to better understand building operation and provide opportunities for energy conservation. DA - 2012/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f802a509-88cb-42b1-bcf4-70abd61a46d1 ER - TY - JOUR TI - A knife-edge measurement of the beam profile of STXM 5.3.2.2 using a focussed ion beam milled metallic glass DO - 10.1016/j.elspec.2012.07.003 AU - Burke, Kerry B. AU - Luber, Erik J. AU - Holmes, Natalie P. AU - Murray, Andrew J. AU - Belcher, Warwick J. AU - Zhou, Xiaojing AU - Mitlin, David AU - Dastoor, Paul C. T2 - Journal of Electron Spectroscopy and Related Phenomena SN - 0368-2048 VL - 185 IS - 11 SP - 453 EP - 457 KW - Scanning transmission X-ray microscopy (STXM) resolution; Focussed ion beam (FIB) milling; Metallic glass AB - We present a simple knife-edge measurement of the STXM 5.3.2.2 synchrotron X-ray beam width. The knife edge was constructed by ion beam milling a metallic glass alloy consisting of 60% gold, 20% nickel and 20% hafnium and was determined to be well-defined to within 2 nm by TEM. An asymmetric beam profile of 120 nm FWHM in the vertical direction and 150 nm FWHM in the horizontal direction was determined and was observed to depart from the expected Airy function profile. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f59d1f31-fadc-4bed-8681-af01de2c901e ER - TY - JOUR TI - Mediatorless amperometric glucose biosensing using 3-aminopropyltriethoxysilane-functionalized graphene DO - 10.1016/j.talanta.2012.05.014 AU - Zheng, Dan AU - Vashist, Sandeep kumar AU - Al-rubeaan, Khalid AU - Luong, John H.T. AU - Sheu, Fwu-shan T2 - Talanta SN - 00399140 VL - 99 SP - 22 EP - 28 KW - Graphene; Glucose biosensor; APTES; Mediatorless; Amperometric; Glucose oxidase AB - A mediatorless glucose biosensor was developed by the immobilization of glucose oxidase (GOx) to graphene-functionalized glassy carbon electrode (GCE). The surface of GCE was functionalized with graphene by incubating it with graphene dispersed in 3-aminopropyltriethoxysilane (APTES), which acted both as a dispersion agent for graphene and as an amine surface modification agent for GCE and graphene. This was followed by the covalent binding of GOx to graphene-functionalized GCE using 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDC) based crosslinking. Graphene provided signal enhancement by providing greater surface area for GOx binding, while APTES-functionalization led to a higher GOx immobilization density by providing free amino groups for crosslinking. The developed biosensor used a redox potential of −0.45 V (vs. Ag/AgCl) for detecting glucose in the diabetic pathophysiological range 0.5–32 mM. There was no interference from endogenous electroactive substances and drug metabolites. The developed biosensor was further validated for detecting blood glucose in commercial artificial blood glucose linearity standards in the range 1.4–27.9 mM. Therefore, it is ideal for diabetic blood glucose monitoring. The developed bioanalytical procedure for preparation of GOx-bound graphene-functionalized GCEs had high production reproducibility and high storage stability, which is appropriate for the commercial mass production of enzyme-bound electrodes. DA - 2012/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 57b794fb-d8f8-4c7e-930e-8219caaa7cef ER - TY - JOUR TI - An investigation of new barium phosphate chemical conversion coating on AZ31 magnesium alloy DO - 10.1016/j.surfcoat.2012.09.009 AU - Chen, Yougui AU - Luan, Ben li AU - Song, Guang-ling AU - Yang, Qi AU - Kingston, David M. AU - Bensebaa, Farid T2 - Surface and Coatings Technology SN - 02578972 VL - 210 SP - 156 EP - 165 KW - Chemical conversion coating; Mg alloy; Barium phosphate; Corrosion AB - Barium phosphate chemical conversion coating is a new research area for the corrosion protection of Mg alloys. We report a new process conducted in a simple solution with Ba(NO3)2 and NH4H2PO4 as the precursors. The influences of pH value and temperature of the coating bath, concentrations of Ba(NO3)2 and NH4H2PO4, and deposition time were evaluated. The coating obtained typically featured a two-layer structure. The chemical compositions and structures were then further characterized with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), revealing an under layer of mixed amorphous phosphates and a top layer of crystalline BaHPO4. The corrosion resistances of bare Mg alloy and those with coatings were compared with electrochemical polarization, showing an improved corrosion resistance of samples with coating. More specifically, the two-layer coating was shown to be more effective than with the under layer coating alone. In addition, adhesion test was also conducted to evaluate the bonding strength and to identify the separation interface of the coatings. DA - 2012/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 73f5ac82-f800-4d84-a5a8-50bf1d498183 ER - TY - JOUR TI - In situ deposition behavior of SiO2 on YSZ-TBC-coated IN738LC during a burner rig test DO - 10.1016/j.surfcoat.2012.03.061 AU - Kim, Min tae AU - Jung, Yong chan AU - Seo, Dongyi T2 - Surface and Coatings Technology SN - 02578972 VL - 206 IS - 22 SP - 4539 EP - 4545 KW - Gas turbine; Burner rig; In situ deposition; Thermal barrier coating; SiO2 AB - This work was planned as a preliminary test to obtain an optimal condition for in situ deposition of SiO2 on zirconia-based thermal barrier coating (TBC)-coated IN738LC specimens using a burner rig. The effect of the in situ deposited SiO2 on the long-term reliability of TBCs upon cyclic burner rig operations will be tested in the next study. Tetraethylorthosilicate (TEOS), the precursor for the deposition, was fed admixed with methanol into the combustion chamber of the burner rig at an exhaust flame temperature of 1530 °C. All five coating processes were selected by varying the concentration of TEOS in the mixture and applied to hollow type pin specimens infixed to the rotating carousel to face the downstream exhaust gas vertically. A total of 1500 cc of the mixture at a given vol.% TEOS was fed evenly to the burner rig for 54 min during the coating process. After the process, TBC spallation was observed on the front side of the specimens processed with 10, 5, and 2 vol.% TEOS, while the specimen of 0.5 vol.% TEOS was coated with a ~ 5 μm thick SiO2 layer without any macroscopic damages. The surface of the coatings consisted of fractal-structured nodules at 10 vol.% TEOS, and of smooth grains at 0.5 vol.% TEOS. The spallation of SiO2-coated TBC was attributed to the thermal mismatch due to the difference in the thermal expansion coefficients of the two materials. Based on these results, the mixing ratio of TEOS to methanol was reduced to 0.3 vol.%, which produced a 1–2 μm thick, smooth and homogenous SiO2 coating without any spallation of TBC. This deposition condition was chosen for the planned test to evaluate on the effects of the in situ deposition of SiO2 on the long-term durability of TBC-coated IN738LC specimens upon cyclic burner rig operations. DA - 2012/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : efdb91d4-d9e3-4afb-90d0-a44751487f24 ER - TY - JOUR TI - Nanopillar niobium oxides as support structures for oxygen reduction electrocatalysts DO - 10.1016/j.electacta.2012.08.005 AU - Bonakdarpour, Arman AU - Tucker, Ryan T. AU - Fleischauer, Michael D. AU - Beckers, Nicole A. AU - Brett, Michael J. AU - Wilkinson, David P. T2 - Electrochimica Acta SN - 0013-4686 VL - 85 SP - 492 EP - 500 KW - Glancing angle deposition; Niobium oxide; Oxygen reduction reaction; Catalyst support AB - Metal oxides such as niobium oxides have been demonstrated as alternative support materials for Pt and non-precious metal catalysts in fuel cells. High surface area and columnar niobium oxide catalyst support structures were produced by the glancing angle deposition (GLAD) technique on 5 mm diameter glassy carbon disks. The columnar structures have lengths of about 500 nm, diameters of 50 nm and an areal density of about 10^9 cm−². Annealing under different gas mixtures (Ar/H2) led to the formation of various oxides (Nb2O5, NbO2, or NbO + NbO2). Pt catalyst, with a loading of 0.1 mgPt cm−², was deposited onto these structures by magnetron sputter deposition. Rotating disk electrode characterization of the samples, performed in 0.1M HClO4 electrolyte at room temperature, revealed surface enhancement factors of up to 11 and oxygen reduction specific activities of ≥1 mA cm−²Pt at 0.9 V (vs. RHE). The impact of annealing on Nb-O phase formation, conductivity, oxygen reduction activity and stability are discussed. DA - 2012/12/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2f0cef6e-2dd0-4796-bb48-e229a8677ccd ER - TY - JOUR TI - Effects of synthesis condition on formation of desired crystal structures of doped-TiO2/carbon composite supports for ORR electrocatalysts DO - 10.1016/j.electacta.2012.05.100 AU - Bing, Yonghong AU - Neburchilov, Vladimir AU - Song, Chaojie AU - Baker, Ryan AU - Guest, Alan AU - Ghosh, Dave AU - Ye, Siyu AU - Campbell, Stephen AU - Zhang, Jiujun T2 - Electrochimica Acta SN - 0013-4686 VL - 77 SP - 225 EP - 231 KW - Doped-TiO2; Thermal hydrolysis; Hybrid support; Oxygen reduction mass activity; Durability of supports; TiO2 anatase-to-rutile transition; PEM fuel cell AB - The composite supports, (Nb0.07Ti0.93O2)25wt%–C75wt% and (Nb0.07Ti0.93O2)70wt%–C30wt%, as well as their supported Pt–Pd alloy electrocatalysts, 20 wt%Pt0.62Pd0.38/((Nb0.07Ti0.93O2)25wt%–C75wt%)80wt% and 20 wt%Pt0.62Pd0.38/((Nb0.07Ti0.93O2)70wt%–C30wt%)80wt% for oxygen reduction reaction (ORR), are synthesized, respectively, using an acid-water based solution as solvent. The effects of three factors, namely concentration of HCl, the ratio of titanium precursor to solvent, and the ratio of metal-oxide to carbon in the composite support, on the TiO2 anatase-to-rutile transition are investigated in an effort to optimize the supports and their supported catalysts with respect to both ORR catalytic activity and durability. Based on both the high ORR activity and durability, these catalysts should be feasible if used in PEM fuel cells as cathode electrocatalysts. DA - 2012/08/30 PY - 2012 LA - eng N1 - Erratum published in volume 103, page 277, July 2013. DOI: 10.1016/j.electacta.2013.05.076 C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2bdd04c5-3529-46f6-9658-eb1dce464848 ER - TY - JOUR TI - Carbon–Nb0.07Ti0.93O2 composite supported Pt–Pd electrocatalysts for PEM fuel cell oxygen reduction reaction DO - 10.1016/j.electacta.2012.04.111 AU - Ignaszak, Anna AU - Song, Chaojie AU - Zhu, Weimin AU - Wang, Yan-Jie AU - Zhang, Jiujun AU - Bauer, Alex AU - Baker, Ryan AU - Neburchilov, Vladimir AU - Ye, Siyu AU - Campbell, Stephen T2 - Electrochimica Acta SN - 0013-4686 VL - 75 SP - 220 EP - 228 KW - Pt–Pd alloys; NbTiO2–carbon composite support; Oxygen reduction reaction; Fuel cell catalysts AB - Carbon–Nb0.07Ti0.93O2 (C67 wt%–(Nb0.07Ti0.93O2)33 wt%) composite support for Pt0.55Pd0.45 alloy catalysts was prepared by hydrolysis of metal alkoxides in the presence of carbon. Physical characterization by XRD, EDX, BET, TEM and TGA showed that the Nb0.07Ti0.93O2 was well distributed on the carbon particle surface with an average particle size of 15 nm, and this support has a high surface area of 176 m2/g and a similar porosity to that of carbon used to prepare this composite support. Pt0.55Pd0.45 alloy nanoparticles were deposited on the composite support to form a Pt0.55Pd0.45/C67 wt%–(Nb0.07Ti0.93O2)33 wt% catalyst, which shows a higher catalytic activity toward ORR than those of monometallic counterpart Pt/C67 wt%–(Nb0.07Ti0.93O2)33 wt%, Pt0.55Pd0.45/C, and Pt0.55Pd0.45/Nb0.07Ti0.93O2. Pt0.55Pd0.45/C67 wt%–(Nb0.07Ti0.93O2)33 wt% showed higher stability than Pt0.55Pd0.45/C, and similar to the commercially available Pt/C catalyst. DA - 2012/07/30 PY - 2012 LA - eng N1 - Erratum published in volume 103, page 276, July 2013. DOI: 10.1016/j.electacta.2013.05.075 C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d0c9de54-8be0-4b44-9a1c-5d479dddafb0 ER - TY - JOUR TI - Synthesis and characterization of Nb-TiO2 mesoporous microsphere and nanofiber supported Pt catalysts for high temperature PEM fuel cells DO - 10.1016/j.electacta.2012.04.028 AU - Bauer, Alex AU - Chevallier, Laure AU - Hui, Rob AU - Cavaliere, Sara AU - Zhang, Jiujun AU - Jones, Deborah AU - Rozière, Jacques T2 - Electrochimica Acta SN - 0013-4686 VL - 77 SP - 1 EP - 7 KW - Niobium doped titanium oxide; Mesoporous microsphere; Nanofiber; Catalyst support; Fuel cells oxygen reduction reaction AB - Two differently structured Nb-doped TiO2 support materials, i.e., mesoporous microspheres and nanofibers, were synthesized and used as Pt catalyst supports for the oxygen reduction reaction (ORR), which is a critical research topic for PEM fuel cells. Compared to a commercially available Pt/C catalyst, improved electrochemical ORR stability was observed when using the novel supports in an acidic environment. XRD, SEM, TEM, and BET were used to characterize the morphologies of these supports and the attached Pt catalyst. Electrochemical methods were used to measure both the ORR mass activity and stability of these materials. Improvement in both the specific area and conductivity were identified as the area for further development. DA - 2012/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5be44366-8055-434e-a3fa-28a722ba614c ER - TY - JOUR TI - ZnMn2O4 nanoparticles synthesized by a hydrothermal method as an anode material for Li-ion batteries DO - 10.1016/j.electacta.2012.03.108 AU - Courtel, Fabrice M. AU - Abu-Lebdeh, Yaser AU - Davidson, Isobel J. T2 - Electrochimica Acta SN - 0013-4686 VL - 71 SP - 123 EP - 127 KW - ZnMn2O4; Hydrothermal; Li-ion batteries; Nanoparticles; Anode material AB - ZnMn2O4 nanoparticles prepared by a hydrothermal synthesis were evaluated as anode material for Li-ion batteries. XRD measurements showed that a ZnMn2O4 I41/amd tetragonal spinel structure was obtained with crystallite sizes ≤5 nm. TEM micrographs showed that particles of about 5 nm in diameter were synthesized. Li/ZnMn2O4 half cell battery cycling showed that the nanoparticles, using lithium salt of carboxymethylcellulose as binder, give a high capacity of 430 mAh g−¹ when cycled 100 times at C/10. DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 56a26879-05d0-452d-87dc-4c933ac6751f ER - TY - JOUR TI - Titanium carbide and its core-shelled derivative TiC@TiO2 as catalyst supports for proton exchange membrane fuel cells DO - 10.1016/j.electacta.2012.03.039 AU - Ignaszak, Anna AU - Song, Chaojie AU - Zhu, Weimin AU - Zhang, Jiujun AU - Bauer, Alex AU - Baker, Ryan AU - Neburchilov, Vladimir AU - Ye, Siyu AU - Campbell, Stephen T2 - Electrochimica Acta SN - 0013-4686 VL - 69 SP - 397 EP - 405 KW - Catalyst support; Titanium carbide; Core–shell structure; Pt and Pt–Pd alloy catalysts; Proton exchange membrane fuel cells AB - Both TiC and core-shelled TiC@TiO2 are investigated as catalyst supports for proton exchange membrane fuel cells (PEMFCs). TiC is thermally stable, possesses both low solubility in sulphuric acid and high electronic conductivity. However, TiC undergoes irreversible electrochemical oxidation in dilute perchloric acid and the operating potential range of 0–1.2 VRHE. TiC@TiO2 core–shell composite is found to be more stable than TiC. Both these materials are used as supports for Pt and Pt–Pd alloy catalysts (Pt/TiC, Pt3Pd/TiC and Pt3Pd/TiC@TiO2) and are synthesized by microwave-assisted polyol process. The catalytic activities of both Pt3Pd/TiC and Pt3Pd/TiC@TiO2 toward the oxygen reduction reaction (ORR) are much higher than those for Pt/TiC. Accelerated durability tests show that TiC supported catalysts are not electrochemically stable. The corresponding TiC@TiO2 supported catalyst is more stable than that supported by TiC, indicating that with a protective oxide layer on the TiC core, TiC@TiO2 is a promising PEMFC catalyst support. DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6fe1cac6-57f3-405f-9948-f9e109ae4525 ER - TY - JOUR TI - Experimental measurement of effective diffusion coefficient of gas diffusion layer/microporous layer in PEM fuel cells DO - 10.1016/j.electacta.2011.12.110 AU - Chan, Carl AU - Zamel, Nada AU - Li, Xianguo AU - Shen, Jun T2 - Electrochimica Acta SN - 00134686 VL - 65 SP - 13 EP - 21 KW - Diffusion; Porous media; Fuel cell; Carbon paper; Gas diffusion layer; Microporous layer; Diffusion coefficient; Knudsen effect; Loschmidt cell AB - Accuracy in the effective diffusion coefficient of the gas diffusion layer (GDL)/microporous layer (MPL) is important to accurately predict the mass transport limitations for high current density operation of polymer electrolyte membrane (PEM) fuel cells. All the previous studies regarding mass transport limitations were limited to pure GDLs, and experimental analysis of the impact of the MPL on the overall diffusion in the porous GDL is still lacking. A modified Loschmidt cell with an oxygen–nitrogen mixture is used in this work to determine the effect of MPL on the effective diffusion coefficients. It is found that Knudsen effects play a dominant role in the diffusion through the MPL where pore diameters are less than 1 μm. Experimental results show that the effective diffusion coefficient of the MPL is only about 21% that of its GDL substrate and Knudsen diffusion accounts for 80% of the effective diffusion coefficient of the GDL with MPL measured in this study. No existing correlations can correlate the effective diffusion coefficient with significant Knudsen contribution. DA - 2012/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 79d00e87-8648-4413-be72-3cc3c91e8fb8 ER - TY - JOUR TI - Cyclic oxidation behavior of a beta gamma powder metallurgy TiAl–4Nb–3Mn alloy coated with a NiCrAlY coating DO - 10.1016/j.surfcoat.2011.12.004 AU - Kim, D.J. AU - Seo, D.Y. AU - Huang, X. AU - Yang, Q. AU - Kim, Y.-W. T2 - Surface and Coatings Technology SN - 02578972 VL - 206 IS - 13 SP - 3048 EP - 3054 KW - Titanium aluminide; Beta gamma alloys; NiCrAlY; Plasma spray; Powder metallurgy; Cyclic oxidation AB - A new beta gamma TiAl–4Nb–3Mn alloy was synthesized by powder metallurgy (PM) and coated with NiCrAlY powder by Air Plasma Spray (APS). The cyclic oxidation behavior of the coated beta gamma alloy was investigated between room temperature and 1000 °C for up to 800 cycles. During cyclic oxidation testing, a TiN layer formed at the interface between NiCrAlY and TiAl–4Nb–3Mn and the thickness of the TiN layer increased with the number of cycles. The outward Ti diffusion also resulted in the formation of titanium oxides on the coating top surface after 630 cycles. Inward diffusion of Ni led to the formation of an inner diffusion zone containing NiAlTi and a mixture of NiAlTi + TiAl. Due to the spallation of coating scales on the circumferential surface, weight loss was observed after 120 cycles although both the top and bottom surfaces of the specimens remain in contact with the substrate until 800 cycles. Due to inward and outward diffusion, half of the NiCrAlY coating was consumed after 800 cycles suggesting the need for diffusion barrier coating at the interface between the NiCrAlY coating and the TiAl–4Nb–3Mn alloy. DA - 2012/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : dcf335d4-128b-46e2-b5fb-3fd2cb4ed981 ER - TY - JOUR TI - Effects of electrode layer composition/thickness and electrolyte concentration on both specific capacitance and energy density of supercapacitor DO - 10.1016/j.electacta.2011.11.087 AU - Tsay, Keh-Chyun AU - Zhang, Lei AU - Zhang, Jiujun T2 - Electrochimica Acta SN - 0013-4686 VL - 60 SP - 428 EP - 436 AB - In this paper, the effects of several experimental conditions, such as electrode layer binder content, conducting carbon content, electrode layer thickness, as well as electrolyte concentration, on both the specific capacitance and energy density of a BP2000 carbon-based supercapacitor are investigated using both cyclic voltammetry and a galvanic charging–discharging curve. The electrode layer studied contains Super C45 carbon as the conducting additive, PTFE as the binder, and Na2SO4 as the aqueous electrolyte, respectively. With the purpose of optimizing the electrode layer structure, 15 wt% of Super C45 and 5 wt% of PTFE in the electrode layer with a thickness of 100 μm, are found to be the best composition in terms of improving both specific capacitance and energy density. Regarding the effect of electrolyte concentration in the range of 0.1–1.0 M, 0.5 M of Na2SO4 gives the best performance. DA - 2012/01/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cae13410-1b7a-4986-8e75-4b6269ef9406 ER - TY - JOUR TI - Diffusion abnormality maps in demyelinating disease: correlations with clinical scores DO - 10.1016/j.ejrad.2011.12.014 AU - Onu, Mihaela AU - Roceanu, Adina AU - Sboto-Frankenstein, Uta AU - Bendic, Robert AU - Tarta, Eugen AU - Preoteasa, Florentin AU - Bajenaru, Ovidiu T2 - European Journal of Radiology SN - 0720-048X VL - 81 IS - 3 SP - e386 EP - e391 KW - Diffusion tensor imaging; TBSS; Multiple sclerosis AB - Background and purpose - Magnetic resonance imaging (MRI) has been explored as a noninvasive tool to assess pathology in multiple sclerosis (MS) patients. However, the correlation between classical MRI measures and physical disability is modest in MS. The diffusion tensor imaging (DTI) MRI technique holds particular promise in this regard. The present study shows brain regions where FA and individual diffusivities abnormalities are present and check their correlations with physical disability clinical scores. Methods - Eight patients and 12 matched healthy controls were recruited. The Multiple Sclerosis Functional Composite was administered. For MR-DTI acquisitions, a Genesis Signa 1.5T MR system, an EP/SE scanning sequence, 25 gradient directions were used. Results - Tract Based Spatial Statistics (TBSS) group comparisons showed reduced FA and increased individual diffusivities in several brain regions in patients. Significant correlations were found between FA and: EDSS, 9-HPT(NON)DOM and 25FW score; between λ2 and: P100 (r&l), 9-HPT(NON)DOM and 25FW; between λ3 and: 9-HPT(NON)DOM and 25FW score. Conclusions - Fractional anisotropy and individual radial diffusivities proved to be important markers of motor disabilities in MS patients when the disease duration mean and the disability scores values range are relatively high. DA - 2012/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4d46ed0c-2c64-4bbf-a6f5-c47e6187fe94 ER - TY - JOUR TI - Single domain antibody against carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) inhibits proliferation, migration, invasion and angiogenesis of pancreatic cancer cells DO - 10.1016/j.ejca.2012.07.019 AU - Cheng, Tsai-Mu AU - Murad, Yanal M. AU - Chang, Chia-Ching AU - Yang, Ming-Chi AU - Baral, Toya Nath AU - Cowan, Aaron AU - Tseng, Shin-Hua AU - Wong, Andrew AU - Mackenzie, Roger AU - Shieh, Dar-Bin AU - Zhang, Jianbing T2 - European Journal of Cancer SN - 0959-8049 KW - CEACAM6; Single domain antibodies; Pancreatic cancer; Gemcitabine; Angiogenesis; MMP-9; BxPC3 AB - Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is over-expressed in pancreatic cancer cells, and it is associated with the progression of pancreatic cancer. We tested a single domain antibody (sdAb) targeting CEACAM6, 2A3, which was isolated previously from a llama immune library, and an Fc conjugated version of this sdAb, to determine how they affect the pancreatic cancer cell line BxPC3. We also compared the effects of the antibodies to gemcitabine. Gemcitabine and 2A3 slowed down cancer cell proliferation. However, only 2A3 retarded cancer cell invasion, angiogenesis within the cancer mass and BxPC3 cell MMP-9 activity, three features important for tumour growth and metastasis. The IC50s for 2A3, 2A3-Fc and gemcitabine were determined as 6.5 μM, 8 μM and 12 nM, respectively. While the 2A3 antibody inhibited MMP-9 activity by 33% compared to non-treated control cells, gemcitabine failed to inhibit MMP-9 activity. Moreover, 2A3 and 2A3-Fc inhibited invasion of BxPC3 by 73% compared to non-treated cells. When conditioned media that were produced using 2A3- or 2A3-Fc-treated BxPC3 cells were used in a capillary formation assay, the capillary length was reduced by 21% and 49%, respectively. Therefore 2A3 is an ideal candidate for treating tumours that over-express CEACAM6. DA - 2012/08/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2f24073c-c7d9-48f4-a3c4-cec1d011a85b ER - TY - JOUR TI - An upper limit on the lateral vacancy diffusion length in diamond DO - 10.1016/j.diamond.2012.02.009 AU - Orwa, J. O. AU - Ganesan, K. AU - Newnham, J. AU - Santori, C. AU - Barclay, P. AU - Fu, K. M. C. AU - Beausoleil, R. G. AU - Aharonovich, I. AU - Fairchild, B. A. AU - Olivero, P. AU - Greentree, A. D. AU - Prawer, S. T2 - Diamond and Related Materials SN - 0925-9635 VL - 24 SP - 6 EP - 10 KW - Ion implantation; Annealing; Vacancy diffusion; Scattering AB - Ion implantation is widely used to modify the structural, electrical and optical properties of materials. By appropriate masking, this technique can be used to define nano- and micro-structures. However, depending on the type of mask used, experiments have shown that vacancy-related substrate modification can be inferred tens of micrometers away from the edge of the mask used to define the implanted region. This could be due to fast diffusion of vacancies from the implanted area during annealing or to a geometric effect related to ion scattering around the mask edges. For quantum and single-atom devices, stray ion damage can be deleterious and must be minimized. In order to profile the distribution of implantation-induced damage, we have used the nitrogen-vacancy color center as a sensitive marker for vacancy concentration and distribution following MeV He ion implantation into diamond and annealing. Results show that helium atoms implanted through a mask clamped to the diamond surface are scattered underneath the mask to distances in the range of tens of micrometers from the mask edge. Implantation through a lithographically defined and deposited mask, with no spacing between the mask and the substrate, significantly reduces the scattering to ≤ 5 μm but does not eliminate it. These scattering distances are much larger than the theoretically estimated vacancy diffusion distance of ~ 260 nm under similar conditions. This paper shows that diffusion, upon annealing, of vacancies created by ion implantation in diamond, is limited, and the appearance of vacancies many tens of micrometers from the edge of the mask is due to scattering effects. DA - 2012/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : eb7cbe48-fdd4-462e-b578-3fe26300697e ER - TY - JOUR TI - A bench scale study of removal of cyclohexane and naphtha components from water by membrane air-stripping process DO - 10.1016/j.desal.2011.10.023 AU - Mahmud, Hassan AU - Kumar, Ashwani T2 - Desalination SN - 0011-9164 VL - 287 SP - 216 EP - 219 KW - Cyclohexane; Naphtha; Organics removal; Hollow fiber; Contactor; Membrane air stripping AB - Removal of hazardous chemicals such as cyclohexane and naphtha components from water with air-stripping (MAS) technique using a polypropylene microporous hollow fiber module is reported. The mass transfer of these organics through the membrane from the water on the feed side to the air stream on the permeate side was evaluated under different experimental conditions in a batch system. Removal of cyclohexane as well as naphtha components by MAS process for the investigated experimental conditions appears to be promising. It was observed in separate experiments that the concentrations of cyclohexane and naphtha components in water were significantly reduced by the MAS process. DA - 2012/02/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f5ca280e-299d-485d-9f0a-9422d4666a3f ER - TY - JOUR TI - Effect of hormone implantation on cryopreservation of Atlantic halibut (Hippoglossus hippoglossus L.) sperm DO - 10.1016/j.cryobiol.2012.04.001 AU - Ding, Fuhong AU - Milley, Joyce E. AU - Rommens, Melissa AU - Li, Jun AU - Lei, Jilin AU - Lall, Santosh P. T2 - Cryobiology SN - 0011-2240 VL - 65 IS - 1 SP - 51 EP - 55 KW - Atlantic halibut (Hippoglossus hippoglossus L.); Hormone (GnRHa); Cryopreservation; Spermotocrit; Fertilization AB - Hormone implantation is widely applied in halibut (Hippoglossus hippoglossus L.) aquaculture to extend the sperm production season of broodstock males. The ability to combine this technique with cryopreservation would increase sperm availability, thereby improving reproduction success and facilitating gene management. In this paper, the cryopreservation ability of sperm from hormone-treated males was examined at three times post-implantation and compared with that of sperm from males that were not hormone-treated. All sperm samples were cryopreserved using the same method. The effectiveness of these techniques was assessed by examining the fertilization rate and motility of thawed sperm. The spermotocrit and concentration of fresh sperm samples were measured to reveal the effect of hormone implantation on sperm characteristics. The reported results indicate that hormone implantation did not affect cryopreservation efficiency. The fertilization rate resulting from thawed sperm of hormone-treated males showed no significant difference from that of untreated males or from fresh sperm. A significant positive relationship was demonstrated between the spermatocrit and concentration of sperm; and a significant decrease of spermatocrit was found in sperm collected from hormone-treated males 14 days post-implantation. No significant linear relationship between spermotocrit and fertilization rate of thawed sperm was shown. DA - 2012/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a5c4bb64-dbc6-41d3-9001-44e30a17edea ER - TY - JOUR TI - Electronic structure of a single MoS2 monolayer DO - 10.1016/j.ssc.2012.02.005 AU - Kadantsev, Eugene S. AU - Hawrylak, Pawel T2 - Solid State Communications SN - 00381098 VL - 152 IS - 10 SP - 909 EP - 913 KW - Nanostructures; Electronic band structure; Optical properties; Electronic transport AB - The electronic structure of a single MoS2 monolayer is investigated with all electron first-principles calculations based on Kohn Sham Density Functional Theory and variational treatment of spin–orbital coupling. The topologies of the valence band maximum and conduction band minimum are explored over the whole Brillouin zone. The single MoS2 monolayer is confirmed to be a direct band gap semiconductor. The projected density of states (PDOS) of a single monolayer is calculated and compared to that of bulk MoS2. The effective masses and the orbital character of the band edges at high-symmetry points of the Brillouin zone are determined. The spin-splittings of the conduction band minimum (CBMIN) and valence band maximum (VBMAX) are calculated over the whole Brillouin zone. It is found that the maximum spin-splitting of VBMAX is attained at the K point of the Brillouin zone and is responsible for the experimentally observed splitting between the A1 and B1 excitons. DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b7166740-92fb-4243-9a4e-ec691964fb8a ER - TY - JOUR TI - Temperature coefficients of the refractive index for hydrocarbons and binary mixtures DO - 10.1016/j.cplett.2012.05.036 AU - Wen, Qing AU - Shen, Jun AU - Shi, Zheng AU - Dy, Eben AU - Michaelian, Kirk H. AU - Fairbridge, Craig AU - Astrath, Nelson G. C. AU - Rohling, Jurandir H. AU - Baesso, Mauro L. T2 - Chemical Physics Letters SN - 0009-2614 VL - 539-540 SP - 54 EP - 57 AB - Temperature coefficients of the refractive index (dn/dT) for nine hydrocarbons and two sets of binary mixtures were investigated in this work. The measured −dn/dT values for the pure hydrocarbons were found to be inversely proportional to their molar volumes (Vm) and molecular weights (M). Experimental data for binary mixtures show that −dn/dT varies linearly with volume and mass fractions, consistent with theory derived from the linear relationships of −dn/dT with 1/Vm and 1/M for individual hydrocarbons. This study should aid the interpretation of the observed correlations of dn/dT with physical and combustion properties of diesel fuels. DA - 2012/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d1d09314-57ad-427f-bb93-fb99ef5460a6 ER - TY - JOUR TI - Angle-resolved XPS study of carbon steel passivity and chloride-induced depassivation in simulated concrete pore solution DO - 10.1016/j.corsci.2012.01.019 AU - Ghods, P. AU - Isgor, O. Burkan AU - Bensebaa, F. AU - Kingston, D. T2 - Corrosion Science SN - 0010-938X VL - 58 SP - 159 EP - 167 KW - Steel reinforced concrete; XPS; Passive films; Passivity AB - The passivity and chloride-induced depassivation of carbon steel in simulated concrete pore (CP) solution (pH = 13.3) was investigated using angle-resolved X-ray photoelectron spectroscopy (XPS). After full passivation, the thickness of the oxide film on steel specimens was approximately 5 nm. The oxide films close to the steel substrate were mainly composed of protective Fe(II) oxides while near the free surface the film consisted mostly of Fe(III) oxides. The addition of chloride to the CP solution decreased the thickness of the oxide film and changed its stoichiometry such that near the film/substrate interface the Fe(II)/Fe(III) decreased. DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e8a700a8-1613-42a1-9b0c-2fa9d10078b2 ER - TY - JOUR TI - Statistical modelling of the coupled effect of mix design and rebar spacing on restricted flow characteristics of SCC DO - 10.1016/j.conbuildmat.2012.04.072 AU - Ammar, Yahia AU - Kamal, Khayat H. AU - Mohammed, Sayed T2 - Construction and Building Materials SN - 0950-0618 VL - 37 SP - 699 EP - 706 KW - Filling ability; Rheology; Self-consolidating concrete; Statistical design; Restricted flow AB - Self-consolidating concrete (SCC) is designed to exhibit high deformability and stability to maintain homogenous suspension of coarse aggregate particles in the mortar during flow to ensure adequate passing ability of the concrete through restricted areas and the filling of the formwork without any consolidation. Proper deformability and uniform suspension of coarse aggregate particles in the matrix are key parameters to ensure successful casting and adequate in situ performance. The required flow properties of concrete are affected by the rheological properties of the mixture and the characteristics of the cast element, including the level of reinforcement. The mixture proportioning of SCC involves tailoring several mixture parameters to achieve adequate stability and reduce the risk of arching of solid particles and blockage at the vicinity of closely spaced obstacles which is required to ensure proper passing ability and flow characteristics. The objective of this study is to evaluate the coupled effect of mixture parameters and density of reinforcement on flow characteristics of SCC using a statistical design approach. This study seeks to model the coupled effect of the content of supplementary cementitious materials (SCMs), coarse aggregate volume (CA), and density of reinforcement on flowability, passing ability, and filling capacity of SCC. The comparison between predicted and measured responses determined on eight mixtures indicates the accuracy of the established models to describe the effect of the independent variables on the flow behavior of SCC through restricted sections. The derived models show that the flow rate of SCC in the presence of reinforcement is dominated by the content of SCM and clear spacing between the reinforcement. On the other hand, the SCM content is shown to have a three-time greater effect on plastic viscosity than the relative volume of coarse aggregate. Trade-offs between rheological parameters, clear spacing, and flow of SCC in the presence of obstacles showed that for a given clear spacing, higher viscosity and lower yield stress values resulted in higher flow time of concrete. For clear spacing between obstacles of 30 mm, SCC mixtures with plastic viscosity lower than 50 Pa s and yield stress of 45 Pa are shown to ensure proper passing ability. DA - 2012/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bfbab0a6-664a-4006-87ae-2d1daba21a46 ER - TY - JOUR TI - Improvement in dynamic properties of laminated MWCNT-polystyrene composite beams via an integrated numerical–experimental approach DO - 10.1016/j.compstruct.2012.03.028 AU - Rokni, Hossein AU - Milani, Abbas S. AU - Seethaler, Rudolf J. AU - Stoeffler, Karen T2 - Composite Structures SN - 0263-8223 VL - 94 IS - 8 SP - 2538 EP - 2547 KW - Structural composites; Carbon nanotubes; Vibration behavior; Testing and modeling AB - A new concept for the optimization of dynamic behavior of laminated nanocomposites is introduced where fiber orientation factor in continuous fiber-reinforced composites is replaced by different wt.% of carbon nanotubes (CNTs) in each layer. First, at a design concept level, an optimum distribution of multi-walled CNTs (MWCNTs) through the thickness of a typical cantilever beam is sought to achieve its highest fundamental natural frequency for a given weight percent of MWCNTs. This is done using a finite element (FE) model in ABAQUS along with a user-defined Python code. Next, based on the obtained optimum distribution, actual laminated MWCNT/polystyrene (PS) composite beams were fabricated and their effective stiffness, fundamental natural frequencies and damping ratios were measured through static deflection and free vibration tests. It was found that the optimum distribution of MWCNTs resulted in an increase of 21.9% and 10.4% in the effective Young’s modulus and the fundamental damped natural frequency values, respectively, which were almost two-fold higher than those of a beam with a uniform MWCNT distribution. In addition, compared to a pure polymer beam, 38.9% and 27.8% improvements in the damping ratio of the uniformly and optimally distributed MWCNT polymer composite beams were achieved. DA - 2012/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c313b598-4601-4bc3-a4ef-0220931e2825 ER - TY - JOUR TI - Buckling of conical composite shells DO - 10.1016/j.compstruct.2011.09.016 AU - Shadmehri, F. AU - Hoa, S. V. AU - Hojjati, M. T2 - Composite Structures SN - 02638223 VL - 94 IS - 2 SP - 787 EP - 792 KW - Conical shells; Composite structures; Buckling analysis AB - A semi-analytical approach is proposed to obtain the linear buckling response of conical composite shells under axial compression load. A first order shear deformation shell theory along with linear strain–displacement relations is assumed. Using the principle of minimum total potential energy, the governing equilibrium equations are found and Ritz method is applied to solve them. Parametric study is performed by finding the effect of cone angle and fiber orientation on the critical buckling load of the conical composite shells. DA - 2012/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 852ecbed-a7f8-489b-ba42-8857cc12a5b7 ER - TY - JOUR TI - Study on laser welding of AA1100-16vol.% B4C metal–matrix composites DO - 10.1016/j.compositesb.2011.11.044 AU - Guo, J. AU - Gougeon, P. AU - Chen, X.-G. T2 - Composites Part B: Engineering SN - 1359-8368 VL - 43 IS - 5 SP - 2400 EP - 2408 KW - Metal–matrix composites (MMCs); Microstructure; Mechanical properties; Joints/joining; Al–B4C AB - Laser welding of AA1100-16 vol.% B4C metal–matrix composites was explored in the study. It was found that most B4C particles were decomposed and that needle-like AlB2 and Al3BC phases were substantially formed during the welding process without filler. Consequently, a joint efficiency of 63% (UTS) was obtained. The addition of Ti with 150 μm thick foil increased the joint efficiency to 75% due to the decrease of needle-like phase formations. On the other hand, the addition of Ti with filler wire did not show significant tensile property improvement due to the Ti segregation and microstructure inhomogeneity in the weld zone. The fracture surfaces of laser welded joints were investigated to understand the fracture mechanisms. DA - 2012/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : de25c06e-347e-499d-914a-cc96715ec735 ER - TY - JOUR TI - The development of a conductive carbon nanotube (CNT) network in CNT/polypropylene composite films during biaxial stretching DO - 10.1016/j.compositesa.2012.04.003 AU - Shen, Jiabin AU - Champagne, Michel F. AU - Yang, Zhi AU - Yu, Qin AU - Gendron, Richard AU - Guo, Shaoyun T2 - Composites Part A: Applied Science and Manufacturing SN - 1359-835X VL - 43 IS - 9 SP - 1448 EP - 1453 KW - Polymer–matrix composites (PMCs); Electrical properties AB - Two developing stages of conducting network in carbon nanotube (CNT)/polypropylene composite films were found during simultaneous biaxial (SIB) stretching and sequential biaxial (SEB) stretching. The electrical resistivity was first increased up to 10¹¹ Ω cm with the extension of the films, regardless of the stretching modes. Once further stretched to 3.5 × 3.5, the SIB- and SEB-stretched films showed reduction of their resistivity of six and eight orders of magnitude, respectively. Microscopic observations revealed that specimens stretching in SEB mode promoted the elongation of CNTs and their clusters, which was apparently more effective for reconnecting adjacent particles and fabricating a new conducting network DA - 2012/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2036c731-eddf-4051-8260-1718bec29689 ER - TY - JOUR TI - Processing and properties of PEEK/glass fiber laminates: effect of addition of single-walled carbon nanotubes DO - 10.1016/j.compositesa.2012.02.022 AU - Ashrafi, Behnam AU - Díez-Pascual, Ana M. AU - Johnson, Leon AU - Genest, Marc AU - Hind, Simon AU - Martinez-Rubi, Yadienka AU - González-Domínguez, Jose M. AU - Teresa martínez, M. AU - Simard, Benoit AU - Gómez-Fatou, Marián A. AU - Johnston, Andrew T2 - Composites Part A: Applied Science and Manufacturing SN - 1359-835X VL - 43 IS - 8 SP - 1267 EP - 1279 KW - Nano-structures; Laminates; Physical properties; Thermoplastic resin AB - This work focuses on the effects of the introduction of unwrapped and wrapped single-walled carbon nanotubes (SWCNTs) on the quality (i.e. void content) and a range of different properties of polyether ether ketone (PEEK)/glass fiber (GF) laminates fabricated through hot-compression processing. The quality of the developed multiscale laminates was evaluated by non-destructive inspection techniques (ultrasonic C-scan and thermography), density measurements as well as optical and scanning electron microscopy analyses. The in-plane and transverse thermal and electrical conductivities as well as Short-Beam-Shear (SBS) strength were measured at different locations within each composite panel. It was found that the addition of SWCNT can have a considerable influence on the porosity of manufactured laminates. In summary, while unwrapped SWCNT generally improved the thermal and electrical properties of the PEEK/GF laminates, composites incorporating compatibilizer exhibited the lowest porosity, the highest electrical conductivity and mechanical properties. DA - 2012/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2f0435ca-30eb-4eda-a8e3-695d559c6853 ER - TY - JOUR TI - Novel wear-resistant materials – Carbon fiber reinforced low-carbon Stellite alloy composites DO - 10.1016/j.compositesa.2011.11.023 AU - Khoddamzadeh, A. AU - Liu, R. AU - Liang, M. AU - Yang, Q. T2 - Composites Part A: Applied Science and Manufacturing SN - 1359-835X VL - 43 IS - 3 SP - 344 EP - 352 KW - Metal–matrix composites (MMCs); Carbon fiber; Wear; Corrosion AB - This paper reports the design and development of a class of new composite materials, which are low-carbon Stellite alloy matrices reinforced with carbon fibers. The focus of the research is to compare the different effects of carbon fibers versus carbides on Stellite alloys. Stellite 25 was selected as the matrix because of its very low carbon content (0.1 wt.%), thus minimal carbide volume fraction. The composite specimens are fabricated using the hot isostatic pressing and sintering techniques. The microstructures of the specimens are examined with optical microscopy in order to identify the possible carbide formation from the carbon fibers. The material characterization of the specimens is achieved through hardness test, sliding wear test and corrosion test. These novel materials exhibit superior properties compared to existing Stellite alloys and are expected to spawn a new generation of materials used for high temperature, severe corrosion, and wear resistant applications in various industries. DA - 2012/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 05d36d78-8bfc-49da-ab2c-cd410960fde2 ER - TY - JOUR TI - Poly(phenylene sulphide) and poly(ether ether ketone) composites reinforced with single-walled carbon nanotube buckypaper: II – mechanical properties, electrical and thermal conductivity DO - 10.1016/j.compositesa.2011.11.003 AU - Díez-Pascual, Ana M. AU - Guan, Jingwen AU - Simard, Benoit AU - Gómez-Fatou, Marián A. T2 - Composites Part A: Applied Science and Manufacturing SN - 1359-835X VL - 43 IS - 6 SP - 1007 EP - 1015 KW - Polymer–matrix composites (PMCs); Carbon nanotube buckypaper; Electrical properties; Mechanical testing AB - The mechanical properties, electrical and thermal conductivity of single-walled carbon nanotube (SWCNT) buckypaper (BP) embedded in poly(ether ether ketone) (PEEK) or poly(phenylene sulphide) (PPS) matrices were investigated. Dynamic mechanical analysis demonstrated a significant increase in the storage modulus and glass transition temperature of the polymers, indicating strong SWCNT–matrix interfacial adhesion. The composites showed improved stiffness and strength, as revealed by tensile and flexural tests, while their ductility and toughness moderately decreased. Exceptional enhancements in the electrical and thermal conductivity of PPS and PEEK were found. Their Young’s moduli and thermal conductivities were compared with the predictions of theoretical models. This investigation indicates that SWCNT-BPs possess great potential to improve the performance of thermoplastics and satisfy a wide variety of demands in multi-disciplinary technological applications. DA - 2012/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bd988516-de3c-41c7-b00f-219766672713 ER - TY - JOUR TI - Poly(phenylene sulphide) and poly(ether ether ketone) composites reinforced with single-walled carbon nanotube buckypaper: I – structure, thermal stability and crystallization behaviour DO - 10.1016/j.compositesa.2011.11.002 AU - Díez-pascual, Ana M. AU - Guan, Jingwen AU - Simard, Benoit AU - Gómez-fatou, Marián A. T2 - Composites Part A: Applied Science and Manufacturing SN - 1359-835X VL - 43 IS - 6 SP - 997 EP - 1006 KW - Thermoplastic resin; Carbon nanotube buckypaper; Thermal properties; Electron microscopy AB - Single-walled carbon nanotube (SWCNT) buckypaper (BP) reinforced-poly(phenylene sulphide) (PPS) and poly(ether ether ketone) (PEEK) composite laminates were manufactured through hot-press processing. Scanning and transmission electron microscopies were used for morphological characterization and qualitative evaluation of the impregnation degree of the BP. The thermal stability, resin and void content of the composites were evaluated through thermogravimetric analysis; a strong increase in the degradation temperatures of the polymers was found. Raman spectra revealed the existence of strong filler–matrix interactions. The glass transition temperature, crystallization and melting behaviour of the composites were investigated through differential scanning calorimetry and their crystalline structure was analyzed by wide angle X-ray diffraction. This investigation confirms that SWCNT-BPs can be used to fabricate high-loading CNT/thermoplastic composites with improved thermal properties. DA - 2012/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ae394a10-0a81-4b54-9b79-8633ec2d6b71 ER - TY - JOUR TI - A fuzzy matchmaking approach for Semantic Web Services with application to collaborative material selection DO - 10.1016/j.compind.2011.10.001 AU - Liu, Min AU - Shen, Weiming AU - Hao, Qi AU - Yan, Junwei AU - Bai, Li T2 - Computers in Industry SN - 0166-3615 VL - 63 IS - 3 SP - 193 EP - 209 KW - Semantic Web Services; Similarity; Matchmaking; Fuzzy-set; Material selection AB - A critical step in the process of reusing existing WSDL-specified services for building web-based applications is the discovery of potentially relevant services. However, the category-based service discovery, such as UDDI, is clearly insufficient. Semantic Web Services, augmenting Web service descriptions using Semantic Web technology, were introduced to facilitate the publication, discovery, and execution of Web services at the semantic level. Semantic matchmaker enhances the capability of UDDI service registries in the Semantic Web Services architecture and it is able to recognize various degrees of matching for Web services. Based on the Semantic Web Service framework, semantic matchmaker, specification matching and probabilistic matching, this paper proposes a fuzzy matchmaking approach for Semantic Web Services to support a more automated and veracious service discovery process in collaborative manufacturing environments. In the proposed approach, the membership function is set up on the semantic information annotated on WSDL specification of a web service, and the similarity of service objects is evaluated by the similarity degree of service attributes. A collaborative material selection case study in the die casting process for thermoelectric fan housing is used to illustrate the proposed approach. DA - 2012/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 385ada14-ae71-49c4-baff-5b23538e10ab ER - TY - JOUR TI - A comprehensive analysis of the morphology of first-year sea ice ridges DO - 10.1016/j.coldregions.2012.05.014 AU - Strub-Klein, Lucie AU - Sudom, Denise T2 - Cold Regions Science and Technology SN - 0165-232X VL - 82 SP - 94 EP - 109 KW - First-year ridges; Ratios; Block dimensions; Macroporosity; Consolidated layer AB - A review of the morphological properties of over 300 full-scale floating first-year sea ice ridges has been made, including measurements from 1971 until the present time. Ridges were examined from the Bering and Chukchi Seas, Beaufort Sea, Svalbard waters, Barents Sea and Russian Arctic Ocean for the Arctic regions; and from the Canadian East Coast, Baltic Sea, Sea of Azov, Caspian Sea and Offshore Sakhalin for the Subarctic (or temperate) regions. Grounded ridges were excluded. A wide catalogue comprising the ridge thicknesses (sail, keel and consolidated layer), widths and angles as well as the macroporosity and the block dimensions is provided. The maximum sail height was found to be 8 m (offshore Sakhalin), and the mean peak sail height was 2.0 m, based on 356 profiles. The mean peak keel depth is 8.0 m, based on 321 profiles. The relationship between the maximum sail height, hs, and the maximum keel depth, hk, for all ridges is best described by the power equation hk = 5.11hs0.69. The correlation differs depending on the region. For Arctic ridges a linear relationship was found to be the best fit (hk = 3.84hs), while for the Subarctic ridges a power relationship (hk = 6.14hs0.53) best fit the data. The ratio of maximum keel to maximum sail is 5.17 on average (based on 308 values), and has also been calculated for each region mentioned above. Arctic ridges generally have a lower keel-to-sail ratio than those in Subarctic regions. The statistical distribution of keel-to-sail ratios is best represented by a gamma distribution. The average sail and keel widths were 12 and 36 m, respectively. The relationships between the sail and keel widths and other geometrical parameters were also determined. Variation of sail and keel thicknesses within individual ridges has been compared with the variability of all ridges. Ridge cross-sectional geometry can vary greatly along the length of a ridge, even over a short distance. A study was made on sail block thicknesses, and it was found that they correlate well with the sail height with a square root model. The typical macroporosity for a first-year ice ridge is 22% (based on 58 values) with an average sail macroporosity of 18% (based on 49 values) and average keel rubble macroporosity of 20% (based on 44 values). The average ridge consolidated layer thickness was 1.36 m based on 118 values. The variation of the consolidated layer was examined, and it was found that the layer tends to grow evenly with time over the width of the ridge cross section. A greater spacing between the measurements seemed to affect the variation, as it decreased with an increasing distance between each borehole. A statistical analysis based on 377 measurements of the consolidated layer of ridges in the Barents Sea showed that the gamma distribution well describes the distribution of the consolidated layer thicknesses in that area. DA - 2012/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 212832db-5b2f-4901-a038-42eac716d054 ER - TY - JOUR TI - On borehole indentor (BHI) measurements and analysis DO - 10.1016/j.coldregions.2012.01.009 AU - Sinha, Nirmal K. AU - Shkhinek, Karl AU - Smirnov, Victor T2 - Cold Regions Science and Technology SN - 0165-232X VL - 76-77 SP - 109 EP - 120 KW - Ice strength; In-situ; Borehole indentor; Failure classification; Acoustic-emissions; Microstructural analysis AB - In situ measurements on stress–indentation curves conducted with the National Research Council (NRC), Canada and the Arctic and Antarctic Research Institute (ARRI), Russia borehole indentors (BHI) are analyzed and classified. This establishes harmony with laboratory observations on stress–strain diagrams and some compatibility with the recommendations (ISO/DIS 19906) on estimating uniaxial ice strengths from BHI strengths. The analysis is devoted mainly to consider the influence of local ice conditions and the indentation rates on the pressure–indentation curves. Simultaneous records of the acoustic emission (AE) detected by accelerometers installed on the ice surface, within 1.5 m of the indentation plate, indicated that major cracks are nucleated at the ice/plate interface. Microstructural analysis of the indented ice confirmed this important conclusion in addition to revealing recrystallization as well as healing activities in the indented ice. An attempt, with extremely limited success, has been made in applying conventional ice failure criteria for predicting the observed stress–indentation curves. Phenomenologically, however, a power-law between the indentation-rate and upper-yield strength exhibits the same rate sensitivity (about 3) usually obtained for strain-rate dependence of uniaxial strengths. Numerical solutions of the rate-sensitive indentation processes must be developed (as has successfully been achieved for uniaxial tests) on microstructure-property based mathematical (rheological) model that includes the effects of the rate-dependent kinetics of deformation, microcracking and crack-enhanced creep. Premature brittle fractures are contact problems and modeling must consider the nucleation of cracks in ice at the ice/plate contact surface. DA - 2012/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 03cf1b46-14b8-47de-a649-fc4ea23d54bd ER - TY - JOUR TI - Advanced MR imaging techniques and characterization of residual anatomy DO - 10.1016/j.clineuro.2012.01.003 AU - Stroman, P. W. AU - Bosma, R. L. AU - Kornelsen, J. AU - Lawrence-Dewar, J. AU - Wheeler-Kingshott, C. AU - Cadotte, D. AU - Fehlings, M. G. T2 - Clinical Neurology and Neurosurgery SN - 03038467 VL - 114 IS - 5 SP - 460 EP - 470 KW - Magnetic resonance imaging (MRI); Clinical applications; Functional MRI; Diffusion tensor imaging; Perfusion; Relaxation times; Multiple sclerosis; Traumatic brain injury AB - Advances in technology in recent decades have contributed to rapid developments in non-invasive methods for imaging human anatomy, and advanced imaging methods are now one of the primary tools for clinical diagnosis after neurological trauma or disease. Here we review the current and upcoming capabilities of one of the most rapidly developing methods, magnetic resonance imaging (MRI). The underlying theory is introduced so that the reasons for the strengths, weaknesses, and future expectations of this method, can be explained. Current techniques for imaging anatomical changes, inflammation, and changes in white matter, axonal integrity, blood flow and function, are reviewed. Applications for specific purposes of assessing traumatic injury in the brain or spinal cord, and for multiple-sclerosis are also presented, and are used as examples of how the advanced techniques are being used in practice. DA - 2012/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1e872076-60a3-42eb-b0c2-dfa447cb36a1 ER - TY - JOUR TI - Application of a new procedure for the optimization of variable thickness drawing of aluminium tubes DO - 10.1016/j.cirpj.2012.03.006 AU - Bihamta, R. AU - Bui, Q. H. AU - Guillot, M. AU - D’Amours, G. AU - Rahem, A. AU - Fafard, M. T2 - CIRP Journal of Manufacturing Science and Technology SN - 1755-5817 VL - 5 IS - 2 SP - 142 EP - 150 KW - Optimization; Finite element method; Metal forming; Tool design; Tube drawing; AA6063 AB - The application of aluminium tubes, especially with variation of thickness, in the structures of various transportation devices like cars and bicycles makes it a point of interest for various designers. In this paper, the variable thickness tube drawing process was studied with a newly developed procedure to evaluate the effect of tools geometries on the maximum possible tube deformation. The procedure applies the desired variation in the design variables (die angle, mandrel angle, and die fillet radius) and the required adjustments and changes in the geometries with the aid of an in-house code automatically. Based on the optimized results, a die and a mandrel were built to verify numerical results in variable thickness tube drawing. The numerical results were compared with the experiments in the prototype machine, which was designed by this group, and acceptable agreements were observed. DA - 2012/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5699a9be-9a82-4193-9675-405310d75d13 ER - TY - JOUR TI - Upward- or downward-breaking cones in ice : which one should you use? DO - 10.1061/9780784412473.071 AU - Barker, A. AU - Sayed, M. T2 - Cold Regions Engineering 2012 : Sustainable Infrastructure Development in a Changing Cold Environment T3 - Cold Regions Engineering 2012 : Sustainable Infrastructure Development in a Changing Cold Environment, August 19-22, 2012, Quebec City, Canada SN - 9780784412473 SP - 715 EP - 724 KW - Ice; Conical structures; Numerical simulations; Confederation Bridge; downward ice breaking AB - As an ice sheet impinges on the surface of a cone, flexural (or bending) failure is likely to take place. That ice failure mode causes substantially lower forces than the case of compressive failure, which would take place if ice is to encounter a vertical structure. Some designs further adopt inverted cones, as downward-breaking of ice may produce lower forces. The present study employs a numerical model of ice dynamics in order to predict ice failure patterns, ice clearing around the structure, and forces on the structure. Performance of the model is validated against tests done in the Esso Resources Canada Ltd. ice basin during 1989 and 1990. The paper then proceeds to examine a test case representing a pier of the Confederation Bridge. The results are compared to available observations. Simulations also examine the role of the slope of the cone and the case of ice failure against inverted cones. Comparison of downward-breaking and upward-breaking indicate that the slope plays a role. For a relatively steep slope of 52°, the downward-breaking cone experiences a substantially lower force than the upward-breaking cone. For a gentler 40° slope, the downward- and upward-breaking cones experienced similar values of peak ice forces. The results have applications for bridge pier and offshore wind turbine tower designs, offshore oil and gas exploration and production structures, and standards development, such as the ISO 19906 Arctic Offshore Structures standard, which also has applications for temperate regions. DA - 2012/08/17 PY - 2012 PB - American Society of Civil Engineers LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9d5f3356-fab8-4fe1-9a2c-a69090bec06a ER - TY - JOUR TI - Characterization and optimization of orbital drilling of woven carbon fiber reinforced epoxy laminates DO - 10.1016/j.cirp.2012.03.089 AU - Sadek, A. AU - Meshreki, M. AU - Attia, M. H. T2 - CIRP Annals - Manufacturing Technology SN - 0007-8506 VL - 61 IS - 1 SP - 123 EP - 126 KW - Drilling; Composite; Defect AB - The emerging process of orbital drilling (OD) can greatly reduce or eliminate the defects associated with the drilling of composites; e.g., delamination, and thermal damage. The effects of the OD process parameters on the hole quality attributes were established in the form of machinability maps; an aspect that has not been reported before. The results showed significant enhancement in the hole quality compared to conventional drilling, due to the reduced axial force and cutting temperature, resulting from the redistribution of the load exerted by cutting edges and the cooling effect of the unstable rotational air flow in the tool-workpiece annular gap. DA - 2012/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 57f854e7-c61e-442a-9f4c-b1952e4c9d6a ER - TY - JOUR TI - Polarity-adjustable reversed phase ultrathin-layer chromatography DO - 10.1016/j.chroma.2012.10.020 AU - Hall, J. Z. AU - Taschuk, M. T. AU - Brett, M. J. T2 - Journal of Chromatography A SN - 0021-9673 VL - 1266 SP - 168 EP - 174 KW - Glancing angle deposition; UTLC; Reversed phase AB - Reversed phase thin layer chromatography (TLC) or high performance thin layer chromatography (HPTLC) plates modified with C18, C8 or C2 to provide the silica-gel stationary phase with different polarities are available on the market, however, reversed phase plates with tunable polarity have not been reported. Given the limited variety of reversed phase plates, mobile phase composition optimization is necessary to obtain better separation of analytes with similar characteristics, which is often a time consuming step. We present polarity-adjustable reversed phase ultrathin-layer chromatography (UTLC) plates, which simplifies the mobile phase screening process and greatly expands the selection of reversed phase plates. The plates were fabricated on glass substrates with SiO2 nanopillars deposited using the glancing angle deposition (GLAD) technique. SiO2 nanopillars were functionalized with octadecyltrichlorosilane to generate a super hydrophobic stationary phase. Unlike commercial silica-gel based stationary phases, the isolated nanopillar architecture presented here exposes a high surface area to post-fabrication surface treatments. In our work, an O2 plasma treatment at different powers, pressures and exposure times was used to shorten the silane carbon chain and introduce COOH groups to the surface, producing plates with finely tunable polarities. Separation of a model dye mixture of Sudan blue and Sudan IV confirmed the tuning of surface polarities by measurement of retention behavior changes. The dye elution order reversed as a result of the change in surface polarity. When the same plasma treatment process was tested on commercial reversed phase plates, separation behavior did not change because the disordered and tortuous silica gel restricts the accessible surface area. Plasma treatment of GLAD structures with highly accessible surfaces improved control over interfacial properties, producing better reverse phase separations. DA - 2012/11/30 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4ce10114-71c4-425a-8a25-90515ae23291 ER - TY - JOUR TI - Analysis of pseudomonas quinolone signal and other bacterial signalling molecules using capillaries coated with highly charged polyelectrolyte monolayers and boron doped diamond electrode DO - 10.1016/j.chroma.2012.06.064 AU - Zhou, Lin AU - Reen, F. Jerry AU - O’Gara, Fergal AU - McSweeney, Christina M. AU - Clarke, Sarah L. AU - Glennon, Jeremy D. AU - Luong, John H. T. AU - McGlacken, Gerard P. T2 - Journal of Chromatography A SN - 0021-9673 VL - 1251 SP - 169 EP - 175 KW - Capillary electrophoresis; PQS; HHQ; Biomarker detection AB - Coated capillary electrophoresis equipped with a boron doped diamond (BDD) electrode was developed for analysis of chemically synthesised 2-heptyl-3-hydroxy-4-quinolone (HHQ), 2-heptyl-3-hydroxy-4-quinolone (PQS), and 2-methyl analogues. Detection was then extended to biological samples. PQS and its biological precursor, HHQ, are two key regulators of bacterial cooperative behaviour known as quorum sensing in the nosocomial pathogen Pseudomonas aeruginosa. The fused silica capillary was coated with a thin layer of poly (diallyldimethylammonium) chloride to reverse the electroosmosis, allowing fast migration of PQS and HHQ with improved selectivity. The four model compounds were baseline resolved using a 50 mM H3PO4–Tris, pH 2.0 buffer with 20% (v/v) acetonitrile as buffer additive. With an injection time of 3 s, the detection limits of four analytes ranging from 60 to 100 nM (S/N = 3) were observed when the BDD electrode was poised at +1.5 V vs. 3 M Ag/AgCl. As expected, no PQS or HHQ was detected from the supernatant of the P. aeruginosa (pqsA) mutant. A concentration of HHQ of 247 μM was detected from the supernatant of the pqsH mutant, which catalyses the conversion of HHQ to PQS in the presence of molecular oxygen by monooxygenase. The separation and detection scheme was applicable to follow the conversion of HHQ to PQS in P. aeruginosa when entering the stationary phase of growth. The results obtained by coated capillary electrophoresis with BDD detection were validated and compared well with LC–MS data. DA - 2012/08/17 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : dd247f8f-f88c-4bd4-af58-b067f8d83b58 ER - TY - JOUR TI - Time resolved chromatograms in ultra-thin layer chromatography DO - 10.1016/j.chroma.2012.05.090 AU - Oko, A. J. AU - Jim, S. R. AU - Taschuk, M. T. AU - Brett, M. J. T2 - Journal of Chromatography A SN - 0021-9673 VL - 1249 SP - 226 EP - 232 KW - Planar chromatography; Ultrathin-layer chromatography; Time resolved thin layer chromatography; Real-time analysis; Automated color-filtered chromatograms AB - Ultrathin-layer chromatography (UTLC) is a recently developed analytical method intended for compact, rapid separations of nanolitre analyte volumes. Optimizing this method's performance requires new measurement techniques compatible with the millimetre length scales and rapid separation dynamics observed in UTLC. We have designed, implemented and characterized a measurement system which records UTLC separations in full color with 32 μm spatial resolution and 33 ms temporal resolution. Our code analyzes multiple tracks per plate, filters analyte spots by color, and automatically generates time-resolved figures of merit. The instrument presented here captures a wealth of information from a UTLC separation, and should provide insight into UTLC physics and improved analytical performance. DA - 2012/08/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 51fcdd96-02af-40b7-8e69-b838346a6afe ER - TY - JOUR TI - Tunable thick polymer coatings for on-chip electrophoretic protein and peptide separation DO - 10.1016/j.chroma.2012.04.009 AU - He, Mei AU - Zeng, Yong AU - Jemere, Abebaw B. AU - Harrison, D. Jed T2 - Journal of Chromatography A SN - 0021-9673 VL - 1241 SP - 112 EP - 116 KW - Microfluidics; Thick polymer coating; Capillary electrophoresis; Open-tubular electrochromatography AB - We report a variety of procedures for fabricating confinement-induced polymer coatings, used to eliminate non-specific protein adsorption and to control electroosmotic flow for microchip capillary electrophoresis. The coating strategy generates relatively thick polymer wall coatings (100–700 nm) and can easily be tuned by adjusting the monomer concentration. 2-hydroxyethyl methacrylate (HEMA) polymer coating, photopatterned in microfluidic channels, effectively reduced protein non-specific adsorption and rendered high efficiency (N/m = ∼3 × 10^6) for protein separation. The coating strategy provides rapid and effective means to create robust wall coatings, with the ability to photograft various surface chemistries onto the coating. [2-(methacryloyloxy) ethyl] trimethylammonium chloride grafted HEMA coated channels showed high durability and reproducibility for generating EOF (RSD = 2.6%, n = 64) over a period of 15 days. Sulfobetaine methacrylate grafted HEMA coated channels allowed separation of BSA digest, 15 peaks resolved in 25 s, with an average N/m of 4 × 10^5. DA - 2012/06/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 938d70aa-bc04-4f03-874c-f0267d8a126a ER - TY - JOUR TI - Proton exchange in acid–base complexes induced by reaction coordinates with heavy atom motions DO - 10.1016/j.chemphys.2012.05.004 AU - Alavi, Saman AU - Taghikhani, Mahdi T2 - Chemical Physics SN - 0301-0104 VL - 402 SP - 105 EP - 112 KW - Proton exchange reactions; Acid–base complexes; Atmospheric acid–base complexes; Acid–water complexes; Electronic structure calculations AB - We extend previous work on nitric acid–ammonia and nitric acid–alkylamine complexes to illustrate that proton exchange reaction coordinates involve the rocking motion of the base moiety in many double hydrogen-bonded gas phase strong acid–strong base complexes. The complexes studied involve the biologically and atmospherically relevant glycine, formic, acetic, propionic, and sulfuric acids with ammonia/alkylamine bases. In these complexes, the magnitude of the imaginary frequencies associated with the proton exchange transition states are <400 cm−1. This contrasts with widely studied proton exchange reactions between symmetric carboxylic acid dimers or asymmetric DNA base pair and their analogs where the reaction coordinate is localized in proton motions and the magnitude of the imaginary frequencies for the transition states are >1100 cm−1. Calculations on complexes of these acids with water are performed for comparison. Variations of normal vibration modes along the reaction coordinate in the complexes are described. DA - 2012/06/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 28af82a9-b13b-4f0f-b82d-f316254bc269 ER - TY - JOUR TI - The dissolution mechanism of sulphur in hydrous silicate melts. I: Assessment of analytical techniques in determining the sulphur speciation in iron-free to iron-poor glasses DO - 10.1016/j.chemgeo.2012.04.027 AU - Klimm, Kevin AU - Kohn, Simon C. AU - O'Dell, Luke A. AU - Botcharnikov, Roman E. AU - Smith, Mark E. T2 - Chemical Geology SN - 0009-2541 VL - 322-323 SP - 237 EP - 249 KW - S K-edge XANES; λ (SKα) wavelength shift; 33S MAS NMR; Raman spectroscopy; Sulphur oxidation state; Silicate glass AB - S K-edge XANES, λ (SKα) wavelength shift, 33S MAS NMR and Raman spectroscopy have been applied to a series of experimentally synthesised hydrous sulphur bearing silicate glasses to determine the oxidation state of sulphur dissolved in the glass. Glasses investigated include soda–lime glass (SLG), K2Si4O9 (KSG) and albitic (Albite) and trondhjemitic (TROND) glass compositions. The four spectroscopic techniques are compared with each other to investigate the applicability of each technique as a method to determine the sulphur oxidation state and structural aspects of sulphur dissolution in silicate melts. XANES and Raman spectroscopy provide the most comprehensive information on the S-speciation and S6 + and S2 − (plus S4 + in the case of XANES) can be detected. XANES allows detection of S-species at lower concentrations (< 50 ppm) than all the other methods. NMR also allows direct determination of S6 + and S2 − in the glasses. However, signal loss in NMR prevents both S6 + and S2 − to be detected simultaneously even in samples where the presence of both species can be confirmed using XANES and Raman. Measuring the λ (SKα) wavelength shift does not provide direct constraints on the S-species in silicate glasses but can be used to determine the S6 +/ΣS when corrected for beam damage. λ (SKα) wavelength shift determination works best for S and Fe-rich glasses because in Fe-free hydrous glasses and at low S contents significant beam damage is observed, requiring an intensive correction procedure to account for changes of S6 +/ΣS during electron beam exposure. The other techniques show either no (NMR and Raman) or minimal (XANES) beam damage that can be easily avoided by moving the sample during spectra acquisition. The linear combination of XANES spectra of glasses containing either only S2 − or S6 + provides direct constraints on the S6 +/ΣS of glasses containing a mixture of S2 − and S6 +. In addition the Raman intensities of bands related to S6 + and S2 − can also be used to quantify S6 +/ΣS and determined values are in good agreement with those obtained by XANES at least for S contents of > 150 ppm. XANES and Raman both show that the dissolution of S2 − is different in Fe-free and Fe-bearing hydrous glasses. In Fe-free glasses S2 − is present as SH− and H2S whereas Fe–S complexes are observed in the presence of Fe. DA - 2012/09/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fd3dcf62-916b-49fd-83b4-69228cedef96 ER - TY - JOUR TI - Enhanced rate of gas hydrate formation in a fixed bed column filled with sand compared to a stirred vessel DO - 10.1016/j.ces.2011.10.030 AU - Linga, Praveen AU - Daraboina, Nagu AU - Ripmeester, John A. AU - Englezos, Peter T2 - Chemical Engineering Science SN - 0009-2509 VL - 68 IS - 1 SP - 617 EP - 623 KW - Carbon dioxide; Natural gas; Gas hydrates; Enhanced kinetics; Porous media; Mass transfer AB - The performance of two gas/liquid contact modes was evaluated in relation to the rate of gas hydrate formation. Hydrate formation experiments were conducted for several gas mixtures relevant to natural gas hydrate formation in the earth (CH4, CH4/C3H8, CH4/C2H6 and CH4/C2H6/C3H8) and two CO2 capture and storage (CO2, CO2/H2/C3H8). One set of experiments was conducted in a bed of silica sand, saturated with water (fixed fed column) while the other experiment was conducted in a stirred vessel for each gas/gas mixture. Both sets of experiments were conducted at a constant temperature. The rate of hydrate formation is customarily correlated with the rate of gas consumption. The results show that the rate of hydrate formation in the fixed bed column is significantly greater and thereby resulted in a higher percent of water conversion to hydrate in lesser reaction time for all the systems studied. DA - 2012/01/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 835272c0-576f-4f12-b88a-0ce9c28c0c5f ER - TY - JOUR TI - Probabilistic modeling of chloride-induced corrosion in concrete structures using first- and second-order reliability methods DO - 10.1016/j.cemconcomp.2012.05.001 AU - Saassouh, Bassem AU - Lounis, Zoubir T2 - Cement and Concrete Composites SN - 0958-9465 VL - 34 IS - 9 SP - 1082 EP - 1093 KW - Chloride ingress; Corrosion initiation; Uncertainty modeling; First- and second-order reliability methods; Importance factor; Probability of corrosion AB - Concrete structures are subjected to chloride-induced corrosion that can lead to shortened service life. Reliable predictions of life cycle performance of concrete structures are critical to the optimization of their life cycle design and maintenance to minimize their life cycle costs. This paper presents two simplified semi-analytical probabilistic models based on the first- and second-order reliability methods to model the uncertainty of the key parameters including surface chloride concentration, chloride threshold, cover depth and diffusion coefficient, which govern the chloride ingress into concrete and corrosion of reinforcing steel. A case study of a reinforced concrete highway bridge deck is used to illustrate the capability and efficiency of these simplified probabilistic models in modeling the uncertainty and predicting the time-dependent probability of corrosion. The models enable to quantify the impact of the different governing parameters on probability of corrosion and service life, which can be used to develop cost-effective management strategies. DA - 2012/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 07e4ee32-6128-4351-b072-bc1e0074c910 ER - TY - JOUR TI - Fine limestone additions to regulate setting in high volume fly ash mixtures DO - 10.1016/j.cemconcomp.2011.09.004 AU - Bentz, Dale P. AU - Sato, Taijiro AU - de la Varga, Igor AU - Weiss, W. Jason T2 - Cement and Concrete Composites SN - 0958-9465 VL - 34 IS - 1 SP - 11 EP - 17 KW - Blended cement; High volume fly ash; Isothermal calorimetry; Limestone; Particle size; Setting; Strength; Ternary blend AB - High volume fly ash (HVFA) concrete mixtures are being considered more frequently due to their cost and sustainability advantages. While the long term performance of these HVFA concretes typically meets or exceeds that of conventional concretes, their early age performance is often characterized by excessive retardation of the hydration reactions, delayed setting times, and low strengths. Extending an HVFA mixture to a ternary blend that incorporates a fine limestone powder may provide a viable solution to these deficiencies, particularly the hydration retardation and setting issues. In this paper, a nano-limestone powder and two other limestone fillers of increasing median particle size (4.4 μm and 16.4 μm) are investigated for their propensity to accelerate early age reactions and reduce setting times in a Class C fly ash/cement blend. The fineness of the limestone has measurable effects on its efficacy in accelerating hydration and decreasing setting times. Companion specimens prepared with a fine silica powder suggest that the fine limestone may act favorably through both a physical and a chemical mechanism. Isothermal calorimetry and Vicat needle penetration measurements on pastes are accompanied by strength measurements on mortars, to verify that the limestone powder substitutions are not negatively impacting strength development. A linear relationship with a reasonable correlation is found to exist between 1 d and 7 d compressive strengths of mortars and their accompanying cumulative heat release values as determined using isothermal calorimetry. DA - 2012/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 121be581-789b-4c1e-9b05-3d9d83eb25f1 ER - TY - JOUR TI - Flocculation of bacteria by depletion interactions due to rod-shaped cellulose nanocrystals DO - 10.1016/j.cej.2012.05.114 AU - Sun, Xiaohui AU - Danumah, Christophe AU - Liu, Yang AU - Boluk, Yaman T2 - Chemical Engineering Journal SN - 1385-8947 VL - 198-199 SP - 476 EP - 481 KW - Flocculation; Bacteria; Depletion; Cellulose nanocrystals AB - We report depletion induced flocculation and phase separation of bacteria due to the presence of rod-shaped nanoparticles by using confocal laser microscopy and turbidity measurements. To investigate the depletion effect of rod shaped nanoparticles in bacteria systems, cellulose nanocrystals with length, L = 90 ± 10 nm, diameter, D = 8 ± 1 nm and zeta potential of 51.5 ± 0.8 mV was used. The flocculation of the Gram-negative bacterium Pseudomanas aeruginosa (average length = 1.2 μm, width = 0.2 μm) was tested. The zeta potential of P. aeruginosa suspended in 10 mM NaCl was −29.84 ± 0.6 mV. Bacterial flocculation was observed at the CNC concentration of less than 0.1% due to the depletion effect. We conclude from our results that rod shaped nanoparticles are very effective for the depletion flocculation of colloidal size bacteria and that phase separation of bacteria can occur at very low concentrations of rodlike CNC particles. DA - 2012/08/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ace5983d-bfc0-4aba-984f-4bd046458b8d ER - TY - JOUR TI - Highly active Pt–Ru nanowire network catalysts for the methanol oxidation reaction DO - 10.1016/j.catcom.2011.11.018 AU - Li, Bing AU - Higgins, Drew C. AU - Zhu, Shaomin AU - Li, Hui AU - Wang, Haijiang AU - Ma, Jianxin AU - Chen, Zhongwei T2 - Catalysis Communications SN - 1566-7367 VL - 18 SP - 51 EP - 54 KW - DMFC; Nanowire networks; Pt–Ru; Methanol oxidation reaction; Electrocatalyst AB - Platinum–ruthenium alloy nanowire networks (Pt–Ru NWNs) have been successfully synthesized by a surfactant assisted soft template strategy, involving the chemical reduction of platinum and ruthenium complexes using sodium borohydride. These materials are investigated as methanol oxidation reaction (MOR) catalysts for fuel cell applications and were found to display exemplary MOR activity and CO tolerance through cyclic voltammetry (CV) testing. Pt–Ru-NWNs investigated in this work are proposed as promising anode replacements to traditional Pt–Ru catalysts in direct methanol fuel cells. DA - 2012/02/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e57fc4a5-fd72-4f21-9e2e-41baa0d23d87 ER - TY - JOUR TI - The structural diversity of lipopolysaccharide expressed by non-typeable Haemophilus influenzae strains 1158 and 1159 DO - 10.1016/j.carres.2012.04.023 AU - Vitiazeva, Varvara AU - Li, Jianjun AU - Hood, Derek W. AU - Moxon, E. Richard AU - Schweda, Elke K. H. T2 - Carbohydrate Research SN - 0008-6215 VL - 357 SP - 98 EP - 110 KW - Haemophilus influenzae, Lipopolysaccharide, Globotetraose, Sialyllactose, Phosphocholine AB - A heterogeneous population of glycoforms expressed by NTHi strains 1158 and 1159 has been elucidated using NMR spectroscopy and capillary electrophoresis coupled to electrospray ionization mass spectrometry (CE-ESI-MS) on O-deacylated LPS (LPS-OH) and core oligosaccharide (OS) materials, as well as HPLC-ESI-MSn on dephosphorylated and methylated OS samples. The most abundant glycoform contained a disaccharide chain: PCho→7)-D-α-D-Hepp-(1→6)-β-D-Glcp linked to HepI from the common structural element of H. influenzae LPS: L-α-D-HepIIIp-(1→2)-[PEtn→6]-L-α-D-HepIIp-(1→3)-L-α-D-HepIp-(1→5)-[PPEtn→4]-α-Kdop-(2→6)-lipid A. Phosphocholine (PCho) was found at two positions in the LPS glycoforms; PCho substituted the 6-position of β-D-Glcp attached to HepIII and was also located at a novel position linked to D-α-D-Hepp; this latter position was determined by structural analysis of LPS from a 1158lpsA mutant strain. Additionally, HPLC-ESI-MSn experiments indicated glycoforms that have chain elongation from HepII, this was found only in glycoforms, which lack the additional heptose in the outer core region. Structural details of these glycoforms were confirmed by analyses of LPS from a 1158losB2 mutant strain; the losB2 gene is required for addition of the d,d-Hep to the outer core region in strain 1158. DA - 2012/08/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 649c7b7c-5069-4f8c-8ae7-c8063b696d14 ER - TY - JOUR TI - Plausible transition states for glycosylation reactions DO - 10.1016/j.carres.2012.03.040 AU - Whitfield, Dennis M. T2 - Carbohydrate Research T3 - The XVI European Carbohydrate Congress, July 3-7, 2012, Sorrento, Italy SN - 0008-6215 VL - 356 SP - 180 EP - 190 KW - Glycosylation; Transition states; Density functional theory; Oxacarbenium ion AB - The Transition State (TS) for any chemical glycosylation reaction is not known with certainty. Both experimental and computational approaches have been limited due to the complexity of the problem. This work describes a preliminary computational ionization approach using density functional theory calculations to arrive at hypothetical TSs. The new TSs contain the glycosyl donor as anomeric triflates, the acceptor as methanol, some CH2Cl2 molecules, and a Li+ ion promoter. In this computational approach all glycosylations are disassociative in that the C-1–OTf bond length is greater then 2 Å before any nucleophilic attack. All nucleophilic attack requires some preassociation of the nucleophile with examples of the pre-attack complexation to donor oxygens. These hypothetical models are intended to guide both experimental and computational approaches to finding TSs for glycosylation reactions that can be used to optimize stereoselectivity of glycosylation. DA - 2012/07/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 54b0da3d-6c71-45dc-9350-d23642e7fc91 ER - TY - JOUR TI - Evaluation of the regioselective delactonization of tri-sialic acid lactone by in-solution molecular dynamics simulation DO - 10.1016/j.carres.2012.02.022 AU - Chen, Chien-Sheng AU - Yu, Yi-Ping AU - Hsu, Chun-Hua AU - Zou, Wei AU - Fang, Jim-Min AU - Wu, Shih-Hsiung T2 - Carbohydrate Research SN - 0008-6215 VL - 354 SP - 87 EP - 93 KW - Sialic acid; Lactone; Regioselectivity; Reactant complex; Molecular dynamics AB - An approximate model for the delactonization of tri-sialic acid lactone is presented with two water-layers that led to neutral hydrolysis of δ-lactone. The hydrolytic reactivity was studied with a 10-ns in-solution molecular dynamics simulation. The initial step of this hydrolysis involves a reactant water nucleophile complex via a proton transfer with another water molecule. Therefore, the probability of water molecules localized at the hydrolytic center correlates to the hydrolysis of δ-lactone. The stepwise delactonization of α2,8-(NeuAc)3 lactone results/resulted from water concentration discrepancy near the carbonyl carbon of lactones in two water oxygen⋯carbonyl carbon shells, and the distances of Odouble bondC⋯Owater layers were 2.8 Å and 5.1 Å. Based on in-solution molecular dynamics study, the motion of water molecules over the re-face of the carbonyl groups was used for the quantitative description of the residence probability, p, whose value is 0.11 for lactone I and 0.33 for lactone II. The geometric criteria used to determine the residence statistics are (1) the distance of water–oxygen⋯carbonyl carbon in less than 5.1 Å and (2) the cone angle, θ, of carbonyl Odouble bondC⋯Owater in the range of 85–115°. As expected, a higher residence probability at lactone II led to its faster hydrolysis. Both the radial g(r) and angular p(θ) pair distribution functions of water oxygen and carbonyl groups of lactones ensure a better surrounding hydration encounter for lactone II. In contrast, water molecules around lactone I are deduced due to a steric hindrance by the turn structure of α2,8-(NeuAc)3 lactone. DA - 2012/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 921eb16c-6992-4bbd-9517-debb2c724dfb ER - TY - JOUR TI - Structural characterization of surface glycans from Clostridium difficile DO - 10.1016/j.carres.2012.02.002 AU - Reid, Christopher W. AU - Vinogradov, Evgeny AU - Li, Jianjun AU - Jarrell, Harold C. AU - Logan, Susan M. AU - Brisson, Jean-Robert T2 - Carbohydrate Research SN - 0008-6215 VL - 354 SP - 65 EP - 73 KW - Clostridium difficile; Lipocarbohydrate; Lipoteichoic acid; Capsular polysaccharide; High-resolution magic angle spinning (HR-MAS) NMR AB - Whole-cell high-resolution magic angle spinning (HR-MAS) NMR was employed to survey the surface polysaccharides of a group of clinical and environmental isolates of Clostridium difficile. Results indicated that a highly conserved surface polysaccharide profile among all strains studied. Multiple additional peaks in the anomeric region were also observed which prompted further investigation. Structural characterization of the isolated surface polysaccharides from two strains confirmed the presence of the conserved water soluble polysaccharide originally described by Ganeshapillai et al. which was composed of a hexaglycosyl phosphate repeat consisting of [→6)-β-D-Glcp-(1-3)-β-D-GalpNAc-(1-4)-α-D-Glcp-(1-4)-[β-D-Glcp(1-3]-β-D-GalpNAc-(1-3)-α-D-Manp-(1-P→]. In addition, analysis of phenol soluble polysaccharides revealed a similarly conserved lipoteichoic acid (LTA) which could be detected on whole cells by HR-MAS NMR. Conventional NMR and mass spectrometry analysis indicated that the structure of this LTA consisted of the repeat unit [→6)-α-D-GlcpNAc-(1-3)-[→P-6]-α-D-GlcpNAc-(1-2)-D-GroA] where GroA is glyceric acid. The repeating units were linked by a phosphodiester bridge between C-6 of the two GlcNAc residues (6-P-6). A minor component consisted of GlcpN-(1-3) instead of GlcpNAc-(1-3) in the repeat unit. Through a 6–6 phosphodiester bridge this polymer was linked to →6)-β-D-Glcp-(1-6)-β-D-Glcp-(1-6)-β-D-Glcp-(1-1)-Gro, with glycerol (Gro) substituted by fatty acids. This is the first report of the utility of HR-MAS NMR in the examination of surface carbohydrates of Gram positive bacteria and identification of a novel LTA structure from Clostridium difficile. DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5f35043a-1455-417f-bcd1-551623235cee ER - TY - JOUR TI - Identification of the methyl phosphate substituent at the non-reducing terminal mannose residue of the O-specific polysaccharides of Klebsiella pneumoniae O3, Hafnia alvei PCM 1223 and Escherichia coli O9/O9a LPS DO - 10.1016/j.carres.2011.11.019 AU - Kubler-Kielb, Joanna AU - Whitfield, Chris AU - Katzenellenbogen, Ewa AU - Vinogradov, Evgeny T2 - Carbohydrate Research SN - 0008-6215 VL - 347 IS - 1 SP - 186 EP - 188 KW - Hafnia; Klebsiella; LPS; Methyl phosphate; O-specific polysaccharide AB - O-specific polysaccharides of Gram-negative bacteria are synthesized by two different mechanisms: polymerization of the pre-formed O-repeating unit or sequential addition of the monosaccharides to the growing polysaccharide chain. In the second case, growth of the polymer can be further subdivided into two groups depending on the presence or absence of a special monosaccharide or non-sugar substituent that terminates the glycan. A family of polymannose O-polysaccharides provides prototypes for the chain terminating process. Polysaccharides of Klebsiella pneumoniae O3, Hafnia alvei PCM 1223, and Escherichia coli O9 have the same penta-mannose repeating unit. E. coli O9a has tetra-mannose repeat and this structure can be produced by mutants of E. coli O9. The mechanism of biosynthesis of H. alvei 1223 O-polysaccharide has not been reported. Here we show that all above polysaccharides contain the same modification at the non-reducing end; presence of a methyl phosphate group at O-3 of α-mannopyranose, that serves as the signal for termination of the chain elongation. DA - 2012/01/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 39c95b95-3dd4-4159-a64f-2555e7f7f866 ER - TY - JOUR TI - Thermal and electrical conductivity of array-spun multi-walled carbon nanotube yarns DO - 10.1016/j.carbon.2011.08.041 AU - Jakubinek, Michael B. AU - Johnson, Michel B. AU - White, Mary Anne AU - Jayasinghe, Chaminda AU - Li, Ge AU - Cho, Wondong AU - Schulz, Mark J. AU - Shanov, Vesselin T2 - Carbon SN - 0008-6223 VL - 50 IS - 1 SP - 244 EP - 248 AB - The electrical resistivity of CNT yarns of diameters 10–34 μm, spun from multi-walled carbon nanotube arrays, have been determined from 2 to 300 K in magnetic fields up to 9 T. The magnetoresistance is large and negative at low temperatures. The thermal conductivity also has been determined, by parallel thermal conductance, from 5 to 300 K. The room-temperature thermal conductivity of the 10 μm yarn is (60 ± 20) W m−¹ K−¹, the highest measured result for a CNT yarn to date. The thermal and electrical conductivities both decrease with increasing yarn diameter, which is attributed to structural differences that vary with the yarn diameter. DA - 2012/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9bc25c17-de35-4a28-8a40-8c1f76f0a478 ER - TY - JOUR TI - Zero peak housing: exploring the possibility of eliminating electrical draws from houses during periods of high demand on the electrical grid DO - 10.1016/j.buildenv.2012.06.019 AU - Pietila, Andrea AU - Beausoleil-Morrison, Ian AU - Newsham, Guy R. T2 - Building and Environment SN - 0360-1323 VL - 58 SP - 103 EP - 113 KW - Zero peak housing; Electric loads; Housing; Air-conditioning (cooling) AB - Residential buildings constitute one of the largest demands for electricity. Although the contribution of air-conditioning to total energy use is quite small in many climates, this end-use can place a disproportionate demand upon the central electrical generation, transmission, and distribution system, particularly in the late afternoon of hot summer days. Even in some heating dominated climates, these can be the times of system-wide peak demand, and it is common for electrical systems (such as in Ontario, Canada) to meet marginal demands during these peak periods using generators fired by GHG-intensive fuels (coal and natural gas). The viability of achieving a zero peak house (ZPH)—a house that draws no electricity from the grid during system-wide peak periods—has been assessed via detailed building performance simulations using a case study house based upon a tract-built design in Toronto, Ontario, Canada. It was found that 41%–51% of the goal of eliminating electricity consumption during the summer Ontario on-peak period (11h00 to 17h00 during weekdays from May 1 through October 31) could be achieved through a combination of architectural, control, efficiency, and occupant behaviour measures. It was also found that the remaining demand for electricity could be completely eliminated using realistically sized photovoltaic and battery systems for on-site generation and storage of electricity. DA - 2012/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bb504d7f-3e9a-4580-b990-8953f2f3f23a ER - TY - JOUR TI - Development and application of a protocol to evaluate impact of duct cleaning on IAQ of office buildings DO - 10.1016/j.buildenv.2012.02.008 AU - Zuraimi, M. S. AU - Magee, Robert AU - Nilsson, Gregory T2 - Building and Environment SN - 0360-1323 VL - 56 SP - 86 EP - 94 KW - Duct cleaning; Test protocol; Airborne; Biocides; Particles; Surface cleanliness AB - Field investigations reporting increased airborne particles concentrations after ventilation duct cleaning (DC) and emissions of biocides following its use in DC highlight a need to protect building occupants from possible exposures to these harmful pollutants. A new protocol was developed to include tests for assessing duct surface cleanliness and harmful airborne pollutant concentrations associated with DC. Two office buildings undergoing DC were chosen to demonstrate the protocol application. The new protocol was tested for surface cleanliness assessment using a combination of visual inspection and a vacuum test method wherever possible. For airborne pollutant concentration assessments, indoor air exposures to total particle, fungi and VOCs were measured. The test application demonstrates that it is possible to determine harmful airborne pollutant concentration levels attributed to DC activities while still maintaining industrial performance standards of surface cleanliness. DA - 2012/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b40a545c-c608-4354-b03e-cfecaf7e1399 ER - TY - JOUR TI - Long-term hygrothermal performance of white and black roofs in North American climates DO - 10.1016/j.buildenv.2011.10.022 AU - Saber, Hamed H. AU - Swinton, Michael C. AU - Kalinger, Peter AU - Paroli, Ralph M. T2 - Building and Environment SN - 0360-1323 VL - 50 SP - 141 EP - 154 KW - White cool roof; Black roof; Energy savings; Moisture accumulation; Hygrothermal modelling; Modified-Bitumen (MOD-BIT) roof AB - When solar radiation hits a roof surface, a part of solar energy is reflected and part is absorbed. The absorbed part of solar energy results in an increase of the surface temperature of the roof. Cool reflective (white) roofs use bright surfaces to reflect a significant portion of the incident short-wave solar radiation, which lowers the surface temperature compared to conventional (black) roofs with bituminous membrane. As such, white roofs help reduce the urban heat island effect during the summer. The question is “do white roofs lead to moisture-related problems in northern and southern climates?” To help answer this question, numerical simulations were conducted to compare the hygrothermal performance of a single kind of white and black roofs under different outdoor and indoor conditions. The outdoor conditions are obtained from the weather database of the National Research Council of Canada, Institute for Research in Construction (NRC–IRC). The indoor conditions are taken based on the European standard (EN 15026) and ASHRAE recommendations for conditioned space. The type of roofs considered in this study is Modified-Bitumen (MOD-BIT) roofing systems. The numerical simulations were conducted for the outdoor climate of Toronto (ON), Montreal (QC), St John’s (NL), Saskatoon (SK), Seattle (WA), Wilmington (NC) and Phoenix (AZ). Results showed that for the outdoor climates of St John’s and Saskatoon, the white roofs could lead to longer-term moisture-related problems. However, for the outdoor climates of Toronto, Montreal, Seattle, Wilmington and Phoenix, buildings with white roofs were shown to have a low risk of experiencing moisture damage. Also, buildings with white roofs in these locations were predicted to show a net yearly energy savings compared to buildings with black roofs. DA - 2012/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 80c865e2-d2fe-494f-a049-073112910680 ER - TY - JOUR TI - 2-BFI ameliorates EAE-induced mouse spinal cord damage: effective therapeutic time window and possible mechanisms DO - 10.1016/j.brainres.2012.09.016 AU - Li, Fang AU - Zhang, Zheng-Xue AU - Liu, Yin-Feng AU - Xu, Hui-Gin AU - Hou, Sheng-Tao AU - Zheng, Rong-Yuan T2 - Brain Research SN - 0006-8993 VL - 1483 SP - 13 EP - 19 KW - EAE; 2-BFI; Inflammatory cytokines; IL-17; IFN-γ; IL-10; Multiple sclerosis; Therapeutic time window AB - Our previous studies showed that ligands to type 2 imidazoline receptors (I2R), including 2-(2-Benzofuranyl)-2-imidazoline (2-BFI) and Idazoxan, were effective in reducing spinal cord inflammation caused by experimental autoimmune encephalomyelitis (EAE). In the present study, we determined the effective therapeutic time window of 2-BFI and found that administration of 2-BFI in mice before the appearance of ascending flaccid paralysis (1–10 days post immunization), but not during the period when neurological deficits occurred (11–20 days post immunization), significantly ameliorated EAE-induced neurobehavioral deficits, reduced the infiltration of inflammatory cells into the spinal cord, and reduced the level of demyelination. More interestingly, giving 2-BFI during 1–10 days post immunization selectively suppressed IL-17 levels in the peripheral blood, which strongly suggests that IL-17 may be a good early marker to indicate EAE progression and that 2-BFI may target CD4+ T lymphocytes, especially Th17 cells to reduce IL-17 expression. Collectively, these studies led us to envisage that 2-BFI can be a useful drug to treat multiple sclerosis (MS) when used in combination with an early indicator of MS progression, such as IL-17. DA - 2012/09/14 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4da8f65d-4e7a-4735-8a5c-6c230af0fdff ER - TY - JOUR TI - The structures of three metabolites of the algal hepatotoxin okadaic acid produced by oxidation with human cytochrome P450 DO - 10.1016/j.bmc.2012.04.046 AU - Liu, Li AU - Guo, Fujiang AU - Crain, Sheila AU - Quilliam, Michael A. AU - Wang, Xiaotang AU - Rein, Kathleen S. T2 - Bioorganic & Medicinal Chemistry SN - 0968-0896 VL - 20 IS - 12 SP - 3742 EP - 3745 KW - Okadaic acid; Dinoflagellate; Algal toxin; Xenobiotic metabolism; Cytochrome P450 AB - Four metabolites of okadaic acid were generated by incubation with human recombinant cytochrome P450 3A4. The structures of two of the four metabolites have been determined by MS/MS experiments and 1D and 2D NMR methods using 94 and 133 μg of each metabolite. The structure of a third metabolite was determined by oxidation to a metabolite of known structure. Like okadaic acid, the metabolites are inhibitors of protein phosphatase PP2A. Although one of the metabolites does have an α,β unsaturated carbonyl with the potential to form adducts with an active site cysteine, all of the metabolites are reversible inhibitors of PP2A. DA - 2012/06/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8ee836b4-a377-41b3-9f12-c8fcf64c92ac ER - TY - JOUR TI - Switchable hydrophilicity solvents for lipid extraction from microalgae for biofuel production DO - 10.1016/j.biortech.2012.05.084 AU - Boyd, Alaina R. AU - Champagne, Pascale AU - Mcginn, Patrick J. AU - Macdougall, Karen M. AU - Melanson, Jeremy E. AU - Jessop, Philip G. T2 - Bioresource Technology SN - 0960-8524 VL - 118 SP - 628 EP - 632 KW - Switchable solvents; Microalgae; Botryococcus braunii; Lipids; Biofuel AB - A switchable hydrophilicity solvent (SHS) was studied for its effectiveness at extracting lipids from freeze-dried samples of Botryococcus braunii microalgae. The SHS N,N-dimethylcyclohexylamine extracted up to 22 wt.% crude lipid relative to the freeze-dried cell weight. The solvent was removed from the extract with water saturated with carbon dioxide at atmospheric pressure and recovered from the water upon de-carbonation of the mixture. Liquid chromatography–mass spectrometry (LC–MS) showed that the extracted lipids contained high concentrations of long chain tri-, di- and mono-acylglycerols, no phospholipids, and only 4–8% of residual solvent. Unlike extractions with conventional organic solvents, this new method requires neither distillation nor the use of volatile, flammable or chlorinated organic solvents. DA - 2012/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e4fbc09c-4610-4fdb-8b9e-087ae45bbdd4 ER - TY - JOUR TI - Reduction of the immunostainable length of the hippocampal dentate granule cells’ primary cilia in 3xAD-transgenic mice producing human Aβ1-42 and tau DO - 10.1016/j.bbrc.2012.09.056 AU - Chakravarthy, Balu AU - Gaudet, Chantal AU - Ménard, Michel AU - Brown, Leslie AU - Atkinson, Trevor AU - Laferla, Frank M. AU - Ito, Shingo AU - Armato, Ubaldo AU - Dal Prà, Ilaria AU - Whitfield, James T2 - Biochemical and Biophysical Research Communications SN - 0006-291X VL - 427 IS - 1 SP - 218 EP - 222 KW - Alzheimer’s disease; Dentate granule cells; Primary cilium; p75NTR; Somatostatin receptor 3 (SSTR3); 3xTg-AD mice AB - The hippocampal dentate gyrus is one of the two sites of continuous neurogenesis in adult rodents and humans. Virtually all dentate granule cells have a single immobile cilium with a microtubule spine or axoneme covered with a specialized cell membrane loaded with receptors such as the somatostatin receptor 3 (SSTR3), and the p75 neurotrophin receptor (p75NTR). The signals from these receptors have been reported to stimulate neuroprogenitor proliferation and the post-mitotic maturation of newborn granule cells into functioning granule cells. We have found that in 6–24-months-old triple transgenic Alzheimer’s disease model mice (3xTg-AD) producing both Aβ1-42 and the mutant human tau protein tauP301L, the dentate granule cells still had immunostainable SSTR3- and p75NTR-bearing cilia but they were only half the length of the immunostained cilia in the corresponding wild-type mice. However, the immunostainable length of the granule cell cilia was not reduced either in 2xTg-AD mice accumulating large amounts of Aβ1-42 or in mice accumulating only a mutant human tau protein. Thus it appears that a combination of Aβ1-42 and tau protein accumulation affects the levels of functionally important receptors in 3xTg-AD mice. These observations raise the important possibility that structural and functional changes in granule cell cilia might have a role in AD. DA - 2012/10/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7488c0f4-76d6-4761-9000-28d067e5efc4 ER - TY - JOUR TI - Neurovascular protection conferred by 2-BFI treatment during rat cerebral ischemia DO - 10.1016/j.bbrc.2012.06.152 AU - Han, Zhao AU - Cheng, Zhao-Hui AU - Liu, Shuang AU - Yang, Jin-Long AU - Xiao, Mei-Juan AU - Zheng, Rong-Yuan AU - Hou, Sheng-Tao T2 - Biochemical and Biophysical Research Communications SN - 0006-291X VL - 424 IS - 3 SP - 544 EP - 548 KW - Focal cerebral ischemia; 2-(2-Benzofu-ranyl)-2-imidazoline; 2-BFI; Middle cerebral artery occlusion model; FITC-dextran AB - Stroke is caused by vascular dysfunction and currently there are no effective therapeutics to stroke induced brain damage. In contrast to an intense emphasis on neuroprotection, relatively few studies have addressed means of vascular protection in cerebral ischemia. Here we discovered that the ligand to immidazolin receptor, 2-BFI, not only provided potent neuroprotection during middle cerebral artery occlusion in rat, which confirmed our previous reports, but also protected the integrity of the cerebral vasculature. Treatment with 2-BFI twice daily after the occlusion of the middle cerebral artery for 14 d significantly improved the neurological deficits, reduced brain infarction, and importantly, protected the cerebral vasculature as evidenced by the increased expression of an endothelial marker, von Willebrand factor, and better preservation of the cerebral vasculature, as viewed under a confocal microscope on rat brain perfused with FITC-labeled dextran. These results indicated that 2-BFI contributes to protection of neurovasculature. Understanding the molecular mechanisms could eventually lead to development of more effective therapies for stroke. DA - 2012/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6f7df61f-e5aa-400f-86f1-b3cd209647da ER - TY - JOUR TI - Identification of protein kinase C inhibitory activity associated with a polypeptide isolated from a phage display system with homology to PCM-1, the pericentriolar material-1 protein DO - 10.1016/j.bbrc.2012.06.093 AU - Chakravarthy, Balu AU - Ménard, Michel AU - Brown, Leslie AU - Atkinson, Trevor AU - Whitfield, James T2 - Biochemical and Biophysical Research Communications SN - 0006-291X VL - 424 IS - 1 SP - 147 EP - 151 KW - Protein kinase C (PKC); Inhibitor; Phage display; Pericentriolar material-1 (PCM-1) protein AB - We had previously identified a protein kinase C (PKC) inhibitor in murine neuroblastoma cells (Chakravarthy et al. [1]). Similar PKC inhibitory activity was also found in adult rat brain. Using polyclonal antibodies raised against the partially purified PKC inhibitor from rat brain as bait, we isolated a putative brain PKC inhibitor using a T-7 phage display system expressing human brain cDNA library. After enriching the phage population expressing the putative PKC inhibitor with four rounds of biopanning using ELISA and in vitro PKC binding assays, we identified a phage clone that expressed a product with significant PKC inhibitory activity. We have cloned and expressed this cDNA in a bacterial system and purified the recombinant protein. This polypeptide (174 amino acids) is highly homologous to a region of the 228-kDa PCM-1, the human pericentriolar material 1 protein. We have mapped this polypeptide’s PKC-inhibitory domain and shown its PKC inhibitory activity in vitro. However, it will need to be determined whether the full-length PCM-1 protein possesses PKC inhibitory activity in vivo, and if so, how this might contribute to PCM-1’s recently demonstrated roles in ciliogenesis and neurogenesis. DA - 2012/07/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bc88feb5-e45f-475d-8452-7c25e140a162 ER - TY - JOUR TI - Ethyl-eicosapentaenoate (E-EPA) attenuates motor impairments and inflammation in the MPTP-probenecid mouse model of Parkinson's disease DO - 10.1016/j.bbr.2011.09.033 AU - Luchtman, D. W. AU - Meng, Q. AU - Song, C. T2 - Behavioural Brain Research SN - 0166-4328 VL - 226 IS - 2 SP - 386 EP - 396 KW - Parkinson's disease; 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; Eicosapentaenoic acid; Behavior; Neurotransmitters; Inflammation AB - Parkinson's disease (PD) is a neurodegenerative disorder, characterized by hypokinesia, but also mood and cognitive disorders. Neuropathologically, PD involves loss of nigrostriatal dopamine (DA) and secondary non-dopaminergic abnormalities. Inflammation may contribute to PD pathogenesis, evident by increased production of pro-inflammatory cytokines. PD onset has been positively associated with dietary intake of omega-(n)-6 polyunsaturated fatty acids (PUFA). On the other hand, omega-(n)-3 PUFA may benefit PD. One of these n-3 PUFA, eicosapentaenoic acid (EPA), is a neuroprotective lipid with anti-inflammatory properties, but its neuroprotective effects in PD are unknown. Thus, we presently tested the hypothesis that EPA can protect against behavioral impairments, neurodegeneration and inflammation in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-probenecid (MPTP-P) mouse model of PD. MPTP-P injections caused hypokinesia in the rotorod and pole test, hyperactivity in the open field, and impaired mice on the cued version (procedural memory) of the Morris water maze. MPTP-P caused a loss of nigrostriatal DA and altered neurochemistry in the frontal cortex and hippocampus. Furthermore, striatal levels of pro-inflammatory cytokines were increased, while the brain n-3/n-6 lipid profile remained unaltered. Feeding mice a 0.8% ethyl-eicosapentaenoate (E-EPA) diet prior to MPTP-P injections increased brain EPA and docosapentaenoic acid (DPA) but not docosahexaenoic acid (DHA) or n-6 PUFA. The diet attenuated the hypokinesia induced by MPTP-P and ameliorated the procedural memory deficit. E-EPA also suppressed the production of pro-inflammatory cytokines. However, E-EPA did not prevent nigrostriatal DA loss. Based on this partial protective effect of E-EPA, further testing may be warranted. DA - 2012/01/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f5e00806-081b-49ac-9c1d-963d9a108e72 ER - TY - JOUR TI - Phthalocyanine tetrasulfonates bind to multiple sites on natively-folded prion protein DO - 10.1016/j.bbapap.2012.03.011 AU - Dee, Derek R. AU - Gupta, Amar Nath AU - Anikovskiy, Max AU - Sosova, Iveta AU - Grandi, Elena AU - Rivera, Laura AU - Vincent, Abhilash AU - Brigley, Angela M. AU - Petersen, Nils O. AU - Woodside, Michael T. T2 - Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics SN - 1570-9639 VL - 1824 IS - 6 SP - 826 EP - 832 KW - Prion protein; Phthalocyanine tetrasulfonate; Ligand binding; ITC; SPR; Fluorescence correlation spectroscopy AB - The phthalocyanine tetrasulfonates (PcTS), a class of cyclic tetrapyrroles, bind to the mammalian prion protein, PrP. Remarkably, they can act as anti-scrapie agents to prevent the formation and spread of infectious, misfolded PrP. While the effects of phthalocyanines on the diseased state have been investigated, the interaction between PcTS and PrP has not yet been extensively characterized. Here we use multiple, complementary assays (surface plasmon resonance, isothermal titration calorimetry, fluorescence correlation spectroscopy, and tryptophan fluorescence quenching) to characterize the binding of PcTS to natively-folded hamster PrP(90–232), in order to determine binding constants, ligand stoichiometry, influence of buffer ionic strength, and the effects of chelated metal ions. We found that binding strength depends strongly on chelated metal ions, with Al³+ -PcTS binding the weakest and free-base PcTS the strongest of the three types tested (Al³+, Zn²+, and free-base). Buffer ionic strength also affected the binding, with Kd increasing along with salt concentration. The binding isotherms indicated the presence of at least two different binding sites with micromolar affinities and a total stoichiometry of ~ 4–5 PcTS molecules per PrP molecule. DA - 2012/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5fe0df17-1843-47b8-9166-98a67fb47f9f ER - TY - JOUR TI - Composition of the mitochondrial electron transport chain in Acanthamoeba castellanii: structural and evolutionary insights DO - 10.1016/j.bbabio.2012.06.005 AU - Gawryluk, Ryan M. R. AU - Chisholm, Kenneth A. AU - Pinto, Devanand M. AU - Gray, Michael W. T2 - Biochimica et Biophysica Acta (BBA) - Bioenergetics SN - 0005-2728 VL - 1817 IS - 11 SP - 2027 EP - 2037 KW - Mitochondrion; Protist; Electron transport chain; Mass spectrometry AB - The mitochondrion, derived in evolution from an α-proteobacterial progenitor, plays a key metabolic role in eukaryotes. Mitochondria house the electron transport chain (ETC) that couples oxidation of organic substrates and electron transfer to proton pumping and synthesis of ATP. The ETC comprises several multiprotein enzyme complexes, all of which have counterparts in bacteria. However, mitochondrial ETC assemblies from animals, plants and fungi are generally more complex than their bacterial counterparts, with a number of ‘supernumerary’ subunits appearing early in eukaryotic evolution. Little is known, however, about the ETC of unicellular eukaryotes (protists), which are key to understanding the evolution of mitochondria and the ETC. We present an analysis of the ETC proteome from Acanthamoeba castellanii, an ecologically, medically and evolutionarily important member of Amoebozoa (sister to Opisthokonta). Data obtained from tandem mass spectrometric (MS/MS) analyses of purified mitochondria as well as ETC complexes isolated via blue native polyacrylamide gel electrophoresis are combined with the results of bioinformatic queries of sequence databases. Our bioinformatic analyses have identified most of the ETC subunits found in other eukaryotes, confirming and extending previous observations. The assignment of proteins as ETC subunits by MS/MS provides important insights into the primary structures of ETC proteins and makes possible, through the use of sensitive profile-based similarity searches, the identification of novel constituents of the ETC along with the annotation of highly divergent but phylogenetically conserved ETC subunits. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 87cee487-825b-4c89-8c30-48622bba682c ER - TY - JOUR TI - A loosely coupled system integration approach for decision support in facility management and maintenance DO - 10.1016/j.autcon.2012.04.003 AU - Shen, Weiming AU - Hao, Qi AU - Xue, Yunjiao T2 - Automation in Construction SN - 0926-5805 VL - 25 SP - 41 EP - 48 KW - Facility lifecycle information integration; Facility management and maintenance; Decision support; Service-oriented architecture; Software agents AB - With the objective of providing the best decision support to facility management and maintenance, this paper presents an agent-based, serviced-oriented approach for integrating data, information, and knowledge captured and accumulated during the entire facility lifecycle from its project planning, design, construction, material/component/equipment procurement, to operation and maintenance. All data/information/knowledge sources and hardware/software applications are loosely integrated through agent-based web services, either proactive or reactive, to provide decision support over all stages of the facility lifecycle, and particularly to optimize facility operations and maintenance. Case studies have been conducted with proof-of-concept prototype implementations to validate the proposed approach. DA - 2012/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9605992f-e498-4bb3-97e7-c7c2b1e68c0b ER - TY - JOUR TI - Comparison of standards for predicting ice forces on arctic offshore structures AU - Frederking, Robert T2 - The Proceedings of the Tenth (2012) ISOPE Pacific/Asia Offshore Mechanics Symposium T2 - Proceedings of the Pacific/Asia Offshore Mechanics Symposiums(ISOPE PACOMS) T3 - The Tenth (2012) ISOPE Pacific/Asia Offshore Mechanics Symposium, October 3-5, 2012, Vladivostok, Russia SN - 1946-004X SN - 9781880653937 SP - 60 EP - 67 KW - ice structure interaction; ice forces; offshore structures standards AB - Ice force predictions using the ISO 19906 Arctic offshore structures standard and three national standards have been compared for structures offshore Sakhalin. A multi-leg structure with leg diameters 18 and 24 m subjected to several design ice conditions, level ice 1.2 m, rafted ice 3.5 m and a first year ridge keel 21 m deep was evaluated. ISO 19906 is the most complete and transparent standard in providing guidance. It incorporates guidance on ice strength from the Russian standard, and ice thickness and geometry effects from the Canadian standard. Further guidance is still needed for multi-leg structures. DA - 2012/10/05 PY - 2012 PB - ISOPE UR - http://www.isope.org/publications/proceedings/ISOPE-PACOMS/PACOMS%202012/papers/P12-07.pdf LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c6465904-f24c-4e0b-8c51-9b6781d2b3c8 ER - TY - JOUR TI - Frailty and survival of older Chinese adults in urban and rural areas: Results from the Beijing Longitudinal Study of Aging DO - 10.1016/j.archger.2011.04.020 AU - Yu, Pulin AU - Song, Xiaowei AU - Shi, Jing AU - Mitnitski, Arnold AU - Tang, Zhe AU - Fang, Xianghua AU - Rockwood, Kenneth T2 - Archives of Gerontology and Geriatrics SN - 0167-4943 VL - 54 IS - 1 SP - 3 EP - 8 KW - Aging; Frailty index; Geographic areas; Rural; Urban; China; Frailty AB - Differences in frailty between rural and urban older adults have been demonstrated in developed countries. It is not understood how the apparently greater differences in living conditions between different types of regions in China may affect health and outcomes of older Chinese adults. Here, a frailty index (FI) based on the accumulation of health deficits was used to investigate health and survival differences in older Chinese men and women. We studied rural (n = 1121) and urban (n = 2136) older adults (55–97 years old) in the Beijing Longitudinal Study of Aging (BLSA), of whom 48.9% (rural) and 35.4% (urban) died over 8 years of follow-up. The FI was generated from 35 self-reported health deficits. The mean FI increased exponentially with age (r² = 0.87) and was higher in women than in men. The death rate increased significantly with increases in the FI, but women showed a lower death rate than did men. The mean FI in urban older adults (0.12 ± 0.10) was lower than that in their rural counterparts (0.14 ± 0.12, p < 0.001). Urban dwellers showed better survival compared with their counterparts in the rural areas. Adjusted by age, sex, and education level, the hazard ratio for death for each increment of the FI was 1.28 for urban people and 1.27 for rural people. Chinese urban dwellers showed better health and survival than rural dwelling older adults. The FI readily summarized health and mortality differences among different geographic regions, reflecting the impact of the environment, socioeconomics, and medical services on deficit accumulation and on survival. DA - 2012/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fb536632-7edf-4199-af83-38f95ce4dddb ER - TY - JOUR TI - Effect of strain and ploidy on growth performance of Atlantic salmon, Salmo salar, following seawater transfer DO - 10.1016/j.aquaculture.2011.12.014 AU - Sacobie, Charles F. D. AU - Glebe, Brian D. AU - Barbeau, Myriam A. AU - Lall, Santosh P. AU - Benfey, Tillmann J. T2 - Aquaculture SN - 0044-8486 VL - 334-337 SP - 58 EP - 64 KW - Triploidy; Atlantic salmon; Insulin-like growth factor-I; Wild and farmed salmon; Mowi; St. John River; Cascade AB - This study examined the effects of strain and ploidy on the growth of Atlantic salmon Salmo salar post-smolts in a 12-week tank trial, using specific growth rate (SGR), condition factor (CF) and plasma insulin-like growth factor I (IGF-I) as indicators of growth. Five strain/ploidy combinations (“populations”) were evaluated: triploids of two domesticated strains (Canadian-origin “Cascade” and Norwegian-origin “Mowi”) and diploids of the same Mowi strain, a top-performing Bay of Fundy commercial strain derived from St. John River stock (SJR, New Brunswick, Canada) and SJR wild origin. All fish were individually PIT-tagged and then reared in 150 L tanks (3 tanks per population), with individual size measurements recorded every 4 weeks. Wild SJR diploids consistently had the highest SGR, higher even than their domesticated counterparts, and triploid Cascades had the lowest. Ploidy did not affect the SGR of Mowi fish, which tended to be intermediate between wild and domesticated SJR diploids. CF at the end of the study followed a similar pattern, with wild and commercial SJR diploids having the highest CF, followed by diploid Mowi, triploid Mowi and triploid Cascade fish. Plasma IGF-I levels increased from the initial sampling to the end of the growth trial for all populations except the commercial SJR diploids, which maintained the highest levels throughout the study. The observations that (a) there can be significant variation among strains for triploid SGR and (b) some wild strains can outperform their domesticated counterparts as diploids, at least under experimental conditions, provide important information to salmon farmers on the successful use of triploids and the need for continued research into broodstock development. DA - 2012/03/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : faa4c065-696f-44f6-8462-a546b0232ac6 ER - TY - JOUR TI - Water condensation on superhydrophobic aluminum surfaces with different low-surface-energy coatings DO - 10.1016/j.apsusc.2011.12.100 AU - Yin, Long AU - Wang, Yuanyi AU - Ding, Jianfu AU - Wang, Qingjun AU - Chen, Qingmin T2 - Applied Surface Science SN - 0169-4332 VL - 258 IS - 8 SP - 4063 EP - 4068 KW - Superhydrophobic; Condensation; Contact angle; Sliding angle; Surface temperature; Relative humidity AB - In this work, we have fabricated superhydrophobic aluminum surfaces by a facile chemical etching method. Surface morphology and composition were studied by using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). To comparatively investigate the effect of environmental factors on superhydrophobic behaviors of surfaces with different low-surface-energy coatings under controllable condensation conditions, contact and sliding angles were measured from −10 °C to 30 °C under relative humidity (RH) of 30, 60 and 90%, respectively. The calculation of the solid–liquid contact area fraction quantitatively explained the increased wettability characterized by descending contact angle and ascending sliding angle under low temperature and high humidity, and indicated a transition of the equilibrium state from Cassie–Baxter to Wenzel on rough surfaces. The wettability restoration test showed that the loss of superhydrophobicity during condensation could be recovered completely after a drying process at room temperature. DA - 2012/02/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0589fe57-d356-4287-98fa-fc98ab40400c ER - TY - JOUR TI - Measurement of 56Fe activity produced in inelastic scattering of neutrons created by cosmic muons in an iron shield DO - 10.1016/j.apradiso.2011.08.003 AU - Krmar, M. AU - Jovančević, N. AU - Nikolić, D. T2 - Applied Radiation and Isotopes SN - 0969-8043 VL - 70 IS - 1 SP - 269 EP - 273 KW - Low background γ spectroscopy; Background radiation; Muon-induced nuclear reactions; Inelastic neutron scattering; Cosmic muons AB - We report on the study of the intensities of several gamma lines emitted after the inelastic scattering of neutrons in 56Fe. Neutrons were produced via nuclear processes induced by cosmic muons in the 20 tons massive iron cube placed at the Earth's surface and used as a passive shield for the HPGe detector. Relative intensities of detected gamma lines are compared with the results collected in the same iron shield by the use of the 252Cf neutrons. Assessment against the published data from neutron scattering experiments at energies up to 14 MeV is also provided. It allowed us to infer the qualitative information about the average energy of muon-created neutrons in the iron shield. DA - 2012/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : be15349b-ead5-4bb2-acbe-9580f839cc6f ER - TY - JOUR TI - Numerical estimation of the effective electrical conductivity in carbon paper diffusion media DO - 10.1016/j.apenergy.2011.08.037 AU - Zamel, Nada AU - Li, Xianguo AU - Shen, Jun T2 - Applied Energy T3 - Fifth International Green Energy Conference, June 1–3, 2010, Waterloo, Ontario, Canada SN - 0306-2619 VL - 93 SP - 39 EP - 44 KW - Effective electrical conductivity; Gas diffusion layer; PEM fuel cells; Carbon paper AB - The transport of electrons through the gas diffusion layer (GDL) of polymer electrolyte membrane (PEM) fuel cells has a significant impact on the optimal design and operation of PEM fuel cells and is directly affected by the anisotropic nature of the carbon paper material. In this study, a three-dimensional reconstruction of the GDL is used to numerically estimate the directional dependent effective electrical conductivity of the layer for various porosity values. The distribution of the fibers in the through-plane direction results in high electrical resistivity; hence, decreasing the overall effective electrical conductivity in this direction. This finding is in agreement with measured experimental data. Further, using the numerical results of this study, two mathematical expressions were proposed for the calculation of the effective electrical conductivity of the carbon paper GDL. Finally, the tortuosity factor was evaluated as 1.7 and 3.4 in the in- and through-plane directions, respectively. DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 82274df0-294a-4984-9be2-e3c654e71145 ER - TY - JOUR TI - Using pyridine as nitrogen-rich precursor to synthesize Co-N-S/C non-noble metal electrocatalysts for oxygen reduction reaction DO - 10.1016/j.apcatb.2012.05.050 AU - Qiao, Jinli AU - Xu, Li AU - Ding, Lei AU - Zhang, Lei AU - Baker, Ryan AU - Dai, Xianfeng AU - Zhang, Jiujun T2 - Applied Catalysis B: Environmental SN - 0926-3373 VL - 125 SP - 197 EP - 205 KW - Non-noble metal catalysts; Cobalt; Pyridine; Oxygen reduction reaction; Fuel cells; Metal–air batteries AB - The development of non-noble metal catalysts is of great interest due to their significant potential application in both fuel cell systems and metal–air batteries, particularly when considering long term commercial deployment. In this regard, novel Co-N-S/C non-noble metal catalysts supported on carbon, are synthesized in this study using a solvent-milling method followed by heat-treatment at elevated temperatures. Pyridine is used as the nitrogen-rich ligand for Co-Nx precursor complex formation. The morphology and composition of the catalyst are characterized by X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM) as well as X-ray photoelectron spectroscopy (XPS). Several catalysts containing different amounts of Co are also synthesized. The optimal Co content is found to be in the range of 10–15 wt% nominal, in terms of catalytic oxygen reduction reaction (ORR) activity. This catalyst shows high electroactivity for the ORR with a high stability in alkaline media. Using rotating disk electrode measurements, and Koutechy–Levich analysis, the overall electron transfer number in the catalyzed ORR is found to be 3.8–4.0, suggesting the catalyzed ORR is a four-electron transfer process from O2 to H2O. DA - 2012/08/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f6ed831b-e6ca-4866-aa70-9cd1dc8f42af ER - TY - JOUR TI - Effects of edge screens on the absorption of blocks of theatre chairs DO - 10.1016/j.apacoust.2011.11.007 AU - Choi, YoungJi AU - Bradley, John S. AU - Jeong, DaeUp T2 - Applied Acoustics SN - 0003-682X VL - 73 IS - 5 SP - 470 EP - 477 KW - Absorption coefficients; Theatre chairs; Edge effects; Screens; Perimeter to area ratio AB - This paper reports new measurement results investigating the use of screens around samples of theatre chairs to minimize edge effects when measuring theatre chair absorption in reverberation chambers. The absorption measurements included both full scale and scale model measurements in reverberation chambers and a model recital hall. The use of screens has been proposed to better approximate the sound absorption of the larger blocks of chairs in auditoria. The method of measuring the absorption of blocks of chairs with screens around their edges and located in the corner of a reverberation chamber did not give results indicative of the values obtained for larger areas in auditoria. The addition of screens around samples of chairs did not eliminate the variation of absorption coefficients with perimeter/area ratio. The results of extrapolations from measurements of blocks of screened chairs to infinite samples gave lower absorption coefficients than found for blocks of unscreened chairs. The absorption of chairs in large performance halls can best be predicted using the P/A method to extrapolate from reverberation chamber measurements of smaller samples of unscreened chairs, with a range of P/A values, to the larger samples and lower P/A ratios of blocks of chairs typical of performance spaces. DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 737f0545-ebb2-48bb-b78e-4cc8e9e4e42d ER - TY - JOUR TI - Degradation and drug release in calcium polyphosphate bioceramics: An MRI-based characterization DO - 10.1016/j.actbio.2012.05.026 AU - Bray, J. M. AU - Filiaggi, M. J. AU - Bowen, C. V. AU - Beyea, S. D. T2 - Acta Biomaterialia SN - 1742-7061 VL - 8 IS - 10 SP - 3821 EP - 3831 KW - Magnetic resonance imaging; Controlled release; Calcium polyphosphate; Bioceramics AB - Degradable, bioceramic bone implants made of calcium polyphosphate (CPP) hold potential for controlled release of therapeutic agents in the treatment of localized bone disease. Magnetic resonance imaging techniques for non-invasively mapping fluid distribution, T1 and T2 relaxation times and the apparent diffusion coefficient were performed in conjunction with a drug elution protocol to resolve free and bound water components within the material microstructure in two CPP formulations (G1 and G2). The T2 maps provided the most accurate estimates of free and bound water, and showed that G1 disks contained a detectable free water component at all times, with drug release dominated by a Fickian diffusion mechanism. Drug release from G2 disks was characterized by a combined diffusional/structural relaxation mechanism, which may be related to the gradual infiltration of a free water component associated with swelling and/or chemical degradation. DA - 2012/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : de0497eb-c7be-4bc3-b3be-8d589d7d6ea9 ER - TY - JOUR TI - Review of standards for ice forces on port structures DO - 10.1061/9780784412473.072 AU - Frederking, R. T2 - Cold Regions Engineering 2012 (15th International Conference on Cold Regions Engineering) T3 - 15th International Conference on Cold Regions Engineering 2012, August 19-22, 2012, Quebec City, Canada SN - 9780784412473 SP - 725 EP - 734 KW - Ice forces; standards; structures AB - Port structures in cold regions generally take the form of large caisson structures or piled structures. There are limited standards for such structures, so the following standards for highway bridges and offshore structures were assessed for application in specifying ice forces on port structures; CSA-S6 Canadian Highway Bridge Design Code, ISO 19906 Arctic offshore structures, CSA-S471 General requirements, design criteria, the environment, and loads, API Recommended Practice 2N Planning, Designing, and Constructing Structures and Pipelines for Arctic Conditions (1995), and Russia’s SNiP 2.06.04-82* Loads and Effects on Hydrotechnical Structures. The ice condition considered was level ice 0.2 to 2 m thick. Three typical structures were evaluated; 1 m diameter pile, 4 m diameter structure and a 50 m wide structure. CSA S6 was found to be best suited for small pile structures (~1 m dia.). For slightly larger structures (~4 m dia.), CSA S6 was the best choice, but ISO 19906 and CSA S471 could be used for ice thickness greater than 1.2 m. Finally, for wide structures CSA S471 was most suitable, but ISO 19906 or API RP 2N could be used for ice thickness greater than 0.6 m and up to 2 m. DA - 2012/08/17 PY - 2012 PB - American Society of Civil Engineers LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e8ab2b5c-16f2-426e-bccd-a01a7417256a ER - TY - JOUR TI - Evaluation of Calanus finmarchicus copepod meal in practical diets for juvenile Atlantic halibut (Hippoglossus hippoglossus) DO - 10.1111/anu.12016 AU - Colombo-Hixson, S. M. AU - Olsen, R. E. AU - Tibbetts, S. M. AU - Lall, S. P. T2 - Aquaculture Nutrition SN - 13535773 VL - 19 IS - 5 SP - 687 EP - 700 KW - Atlantic halibut; Calanus finmarchicus; digestibility; protein; zooplankton AB - The copepod, Calanus finmarchicus, has potential as a new ingredient in practical feeds for marine fish. Two experiments were conducted to evaluate the nutritional value of C. finmarchicus meals when fed to juvenile Atlantic halibut. The first study determined protein, lipid and energy digestibility coefficients of four C. finmarchicus meals prepared under different processing conditions. The second study evaluated growth and nutrient utilization efficiency of juveniles fed diets containing varying proportions of fish meal, plant meals and C. finmarchicus meal. Moisture, ash, protein, lipid and gross energy contents of the C. finmarchicus meals were 28–93, 74–138, 505–648, 123–269 g kg-¹, and 21–26 MJ kg-¹, respectively. Protein, lipid and energy digestibilities of C. finmarchicus meals were 91–99%, 90–95% and 90–99%. The digestibilities significantly decreased for the Calanus meals processed at higher temperatures. During the growth study, halibut fed a diet containing 240 g kg-¹ C. finmarchicus meal had significantly higher weight gain and growth rate than all other groups. Nitrogen and energy retention efficiencies ranged between 35–45% and 33–43%, and were significantly higher for fish fed 160–240 g kg-¹ C. finmarchicus meal than for fish fed plant protein and control diets. The results indicate that growth and nutrient utilization efficiency are improved in Atlantic halibut fed diets supplemented with C. finmarchicus meal. DA - 2012/12/31 PY - 2012 PB - John Wiley & Sons LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 05731e64-b0f3-4d26-b35e-04a24294b1bb ER - TY - JOUR TI - Gravitational collapse of rectangular granular piles AU - Babaei, M. H. AU - Dabros, T. AU - Savage, S. B. T2 - Proceedings of the 2012 COMSOL Conference T3 - COMSOL Conference, Oct. 3-5, 2012, Boston, MA KW - gravitational collapse; granular pile; two-phase flow; von Mises yield function; Mohr-Coulomb yield surface; CFD AB - In this study, the dam-break type two-dimensional gravitational collapse of rectangular granular piles in air was numerically studied. The frictional behavior of the material was based on the von Mises model with the Mohr-Coulomb yield surface leading to pressure and strain-rate-dependence of shear viscosity. The governing equations of the problem were solved using the COMSOL two-phase flow CFD Module with the level-set method used for accurate tracking of interfaces. This model successfully captured the stable heaps formed at the end of the collapse. The evolutions of shape and velocity field for collapsing piles of two different initial pile orientations (aspect ratios) were investigated. The comparison of the final shapes of the collapsed piles was in accordance with the experimental measurements available in the literature. DA - 2012/10/05 PY - 2012 PB - COSMOL LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 20ce5354-886a-45ef-88f5-a23877256ecc ER - TY - JOUR TI - The binomial distribution of hydrogen and deuterium in arsanes, diarsanes, and triarsanes generated from As(Ιιι)/[BHnD4-n]− and the effect of trace amounts of Rh(Ιιι) ions DO - 10.1007/s13361-012-0489-5 AU - Pagliano, Enea AU - D’Ulivo, Alessandro AU - Mester, Zoltán AU - Sturgeon, Ralph E. AU - Meija, Juris T2 - Journal of The American Society for Mass Spectrometry SN - 1044-0305 SN - 1879-1123 VL - 23 IS - 12 SP - 2178 EP - 2186 KW - hydride generation; statistical modeling; arsane, diarsane and triarsane; mechanistic interference AB - Recent studies of the formation of arsane in the borohydride/arsenate reaction demonstrate the occurrence of condensation cascades whereby small quantities of di- and triarsanes are formed. In this study, the isotopic composition of these di- and triarsanes was examined using deuterium labelled borohydrides. A statistical model was employed to construct the mass spectra of all diarsane and triarsane isotopologues (As2H n D4-n and As3H n D5-n) from the mass spectra of isotopically pure compounds (As2H4, As2D4, As3H5, and As3D5). Subsequent deconvolution of the experimental mixed spectra shows that incorporation of hydrogen closely follows the binomial distribution, in accord with arsane formation. The H/D distribution in arsane, diarsane, and triarsane isotopologues is binomial in the absence of any interference. However, this is significantly altered by the presence of some transition metals; presented here, for the first time, are the effects of Rh(Ιιι). The presence of Rh(Ιιι) in the As(Ιιι)/[BD4]− system entails the incorporation of hydrogen into the arsanes arising from the solvent, altering the expected binomial H/D distribution. DA - 2012/12/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 911f8fa2-3e1d-4563-b484-e8d4033ed746 ER - TY - JOUR TI - Iodination on tyrosine residues during oxidation with sodium periodate in solid phase extraction of N-linked glycopeptides DO - 10.1007/s13361-011-0262-1 AU - Cohen, Alejandro M. AU - Kostyleva, Ripsik AU - Chisholm, Kenneth A. AU - Pinto, Devanand M. T2 - Journal of The American Society for Mass Spectrometry SN - 1044-0305 SN - 1879-1123 VL - 23 IS - 1 SP - 68 EP - 75 KW - Glycoproteomics; Iodination; N-linked glycoproteins; Hydrazide modified solid phase extraction; Oxidation; Sodium periodate AB - Solid-phase extraction of N-linked glycopeptides (SPEG) using hydrazide-modified supports has become a common sample preparation procedure in glycoproteomic experiments. We demonstrate that iodination of tyrosine residues occur in SPEG as a side reaction during an oxidation step with sodium periodate. MS/MS analysis of oxidized bovine serum albumin and carbonic anhydrase digests revealed a characteristic shift of m/z 125.9 on all y and b fragment ions containing the modified tyrosine residues. Selected reaction monitoring (SRM) measurements showed that the peak intensity from of the iodinated peptides increased during the course of oxidation. After an hour of oxidation, SRM analysis revealed that the strongest signal from an iodinated peptide was approximately one-tenth of the intensity of the corresponding unmodified peptide. Iodinated tyrosine residues were also identified in serum samples subjected to SPEG and analyzed by LC-ESI-MS/MS. We recommend assessing this side reaction by including iodotyrosine as a variable modification when performing database searches on SPEG experiments. For SRM-based acquisitions, we encourage the avoidance of tyrosine-containing glycopeptides or, if this is not practical, monitoring transitions that contain the potential modified iodinated tyrosine residue to monitor the presence of the iodinated form of the glycopeptide. DA - 2012/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0dcf4b3e-f490-4c73-9cfc-b3438a967f67 ER - TY - JOUR TI - Expression of recombinant Atlantic salmon serum C-type lectin in Drosophila melanogaster Schneider 2 cells DO - 10.1007/s10616-012-9505-7 AU - Uribe, Elke AU - Venkatesan, Meenakshi AU - Rose, David R. AU - Ewart, Kathryn Vanya T2 - Cytotechnology SN - 0920-9069 SN - 1573-0778 VL - 65 IS - 4 SP - 513 EP - 521 KW - Atlantic salmon; C-type lectin; Drosophila; Innate immunity; Protein expression; Protein purification; Salmo salar AB - The Atlantic salmon (Salmo salar) serum lectin (SSL) is a soluble C-type lectin that binds bacteria, including salmon pathogens. This lectin is a cysteine-rich oligomeric protein. Consequently, a Drosophila melanogaster expression system was evaluated for use in expressing SSL. A cDNA encoding SSL was cloned into a vector designed to express it as a fusion protein with a hexahistidine tag, under the control of the Drosophila methallothionein promoter. The resulting construct was stably transfected into Drosophila S2 cells. After CdCl2 induction, transfected S2 cells secreted recombinant SSL into the cell culture medium. A cell line derived from stably transformed polyclonal cell populations expressing SSL was used for large-scale expression of SSL. Recombinant SSL was purified from the culture medium using a two-step purification scheme involving affinity binding to yeast cells and metal-affinity chromatography. Although yields of SSL were very low, correct folding and functionality of the recombinant SSL purified in this manner was demonstrated by its ability to bind to Aeromonas salmonicida. Therefore, Drosophila S2 cells may be an ideal system for the production of SSL if yields can be increased. DA - 2012/10/18 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4dda93b4-d6f8-449f-9b93-afb659a81e71 ER - TY - JOUR TI - Effect of Si and Fe doping on calcium phosphate glass fibre reinforced polycaprolactone bone analogous composites DO - 10.1016/j.actbio.2011.12.030 AU - Mohammadi, M. Shah AU - Ahmed, I. AU - Muja, N. AU - Almeida, S. AU - Rudd, C. D. AU - Bureau, M. N. AU - Nazhat, S. N. T2 - Acta Biomaterialia SN - 1742-7061 VL - 8 IS - 4 SP - 1616 EP - 1626 KW - Phosphate-based glass fibres; Biodegradable composites; Bioactivity; Preosteoblast; Tissue engineering AB - Reinforcing biodegradable polymers with phosphate-based glass fibres (PGF) is of interest for bone repair and regeneration. In addition to increasing the mechanical properties, PGF can also release bioinorganics, as they are water soluble, a property that may be controllably translated into a fully degradable composite. Herein, the effect of Si and Fe on the solubility of calcium-containing phosphate-based glasses (PG) in the system (50P2O5–40CaO–(10 − x)SiO2−xFe2O3, where x = 0, 5 and 10 mol.%) were investigated. On replacing SiO2 with Fe2O3, there was an increase in the glass transition temperature and density of the PG, suggesting greater crosslinking of the phosphate chains. This significantly reduced the dissolution rates of degradation and ion release. Two PG formulations, 50P2O5–40CaO–10Fe2O3 (Fe10) and 50P2O5–40CaO–5Fe2O3–5SiO2 (Fe5Si5), were melt drawn into fibres and randomly incorporated into polycaprolactone (PCL). Initially, the flexural strength and modulus significantly increased with PGF incorporation. In deionized water, PCL–Fe5Si5 displayed a significantly greater weight loss and ion release compared with PCL–Fe10. In simulated body fluid, brushite was formed only on the surface of PCL–Fe5Si5. Dynamic mechanical analysis in phosphate buffered saline (PBS) at 37 °C revealed that the PCL–Fe10 storage modulus (E′) was unchanged up to day 7, whereas the onset of PCL–Fe5Si5 E′ decrease occurred at day 4. At longer-term ageing in PBS, PCL–Fe5Si5 flexural strength and modulus decreased significantly. MC3T3-E1 preosteoblasts seeded onto PCL–PGF grew up to day 7 in culture. PGF can be used to control the properties of biodegradable composites for potential application as bone fracture fixation devices. DA - 2012/01/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 425a7a51-931f-4a96-aca5-f1646de8d958 ER - TY - JOUR TI - Engineered peptides with enzymatically cleavable domains for controlling the release of model protein drug from “soft” nanoparticles DO - 10.1016/j.actbio.2011.10.028 AU - Singh, Harsh Deep AU - Bushnak, Ibraheem AU - Unsworth, Larry D. T2 - Acta Biomaterialia SN - 1742-7061 VL - 8 IS - 2 SP - 636 EP - 645 KW - BSA; Coacervation; Engineered peptide; MMP-2; Controlled release strategy AB - Matrix metalloproteinase-2 (MMP-2) is an endopeptidase that has been shown to be present in high concentrations during most tissue remodeling events, including disease states like active tumor sites, thus making it an attractive molecule for use in effecting local delivery of therapeutic molecules. Moreover, the use of non-toxic and biodegradable nanoparticles for controlled drug delivery is highly sought after. To this end, bovine serum albumin (BSA) nanoparticles (NPs) were stabilized with coatings formed using domains of varying sensitivity to MMP-2, viz. K6GPQG/IASQK6 and K6HPVG/LLARK6, lysine residues being used to facilitate peptide immobilization to the BSA NPs via electrostatic interactions, and peptide domains that have a high (HPVG/LLAR) and low (GPQG/IASQ) MMP-2 cleavage rate. The MMP-2-induced cleavage rates of these two domains (the position of action being noted with a “/”) have differing kinetics that can be used to provide a novel mechanism for facilitating the controlled release of molecules where local concentrations of MMP-2 are high. It was found that both surface concentration and cleavage domain type influenced the release of the model drug (BSA) from these NPs. This stratagem may provide a novel pathway for developing multi-functional coatings for controlling the local delivery of therapeutics at sites where the presence of various enzymes exist as a function of tissue state. DA - 2012/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1a339ab5-581e-484c-98ad-3823b8b248bc ER - TY - JOUR TI - TEM analysis of the microstructure in TiF3-catalyzed and pure MgH2 during the hydrogen storage cycling DO - 10.1016/j.actamat.2012.07.036 AU - Danaie, Mohsen AU - Mitlin, David T2 - Acta Materialia SN - 1359-6454 VL - 60 IS - 19 SP - 6441 EP - 6456 KW - Hydrogen storage; Magnesium hydride; Transmission electron microscopy AB - We utilized transmission electron microscopy (TEM) analysis, with a cryogenically cooled sample stage, to detail the microstructure of partially transformed pure and titanium fluoride-catalyzed magnesium hydride powder during hydrogenation cycling. The TiF3-catalyzed MgH2 powder demonstrated excellent hydrogen storage kinetics at various temperatures, whereas the uncatalyzed MgH2 showed significant degradation in both kinetics and capacity. TEM analysis on the partially hydrogen absorbed and partially desorbed pure Mg(MgH2) revealed a large fraction of particles that were either not transformed at all or were completely transformed. On the other hand, in the MgH2+TiF3 system it was much easier to identify regions with both the hydride and the metal phase coexisting in the same particle. This enabled us to establish the metal hydride orientation relationship (OR) during hydrogen absorption. The OR was determined to be (1 1 0)MgH2 || (−1 1 0 −1)Mg and [−1 1 1]MgH2 || [0 1 −1 1]Mg. During absorption the number density of the hydride nuclei does not show a dramatic increase due the presence of TiF3. Conversely, during desorption the TiF3 catalyst substantially increases the number of the newly formed Mg crystallites, which display a strong texture correlation with respect to the parent MgH2 phase. Titanium fluoride also promotes extensive twinning in the hydride phase. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 09a86622-bcf4-4391-9379-e5ad5d368f82 ER - TY - CHAP TI - InP-based quantum dot lasers DO - 10.1016/B978-0-12-391066-0.00011-3 AU - Poole, Philip T2 - Advances in Semiconductor Lasers SN - 0080-8784 SN - 9780123910660 SP - 419 EP - 453 KW - Laser; Quantum dot; InP; InAs; Mode locked; Semiconductor optical amplifier AB - Quantum dot-based lasers have long been predicted to have interesting properties as well as performance advantages over more conventional quantum well-based devices. The development of InP-based quantum dot lasers for use in the 1.55 μm wavelength range is discussed here. The growth of high-quality quantum dots in this wavelength range is first described, followed by their use for laser-type applications. The performance of simple Fabry–Perot lasers is discussed with demonstrations of their high-speed dynamics and advantages for amplifier applications. The large spectra bandwidth of the gain and fast dynamics are used to produce record short pulse widths and high-repetition rate mode-locked lasers. The quantum dot gain medium is also demonstrated to have interesting properties for single frequency lasers, with very narrow linewidths and high side-mode suppression ratios. Although still in its infancy, InP-based quantum dot lasers are already demonstrating high performance as well as novel characteristics. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ff6a3bdf-e22b-497c-adb2-a9b0a3f8c2ff ER - TY - JOUR TI - A TEM based study of the microstructure during room temperature and low temperature hydrogen storage cycling in MgH2 promoted by Nb–V DO - 10.1016/j.actamat.2012.06.009 AU - Tan, XueHai AU - Zahiri, Beniamin AU - Holt, Chris M. B. AU - Kubis, Alan AU - Mitlin, David T2 - Acta Materialia SN - 1359-6454 VL - 60 IS - 16 SP - 5646 EP - 5661 KW - Hydrogen storage; Magnesium hydride; TEM; Microstructure; Catalyst AB - Magnesium hydride combined with a new bimetallic Nb–V catalyst displays remarkably rapid and stable low temperature (200 °C) hydrogen storage kinetics, even after 500 full volumetric absorption/desorption cycles. The system is also able to fairly rapidly absorb hydrogen at room temperature at a pressure of 1 bar. This unprecedented absorption behavior was demonstrated for 20 cycles. We employed extensive cryo-stage transmission electron microscopy (TEM) analysis on fully and partially sorbed materials to provide insight into the rapid Mg to MgH2 phase transformation. After extended cycling of what was initially a 1.5 μm thick fully dense alloy film, the sample structure becomes analogous to that of a weakly agglomerated nanocomposite powder. The cycled Mg–V–Nb structure consists of a dense distribution of catalytic Nb–V nanocrystallites covering the surfaces of larger Mg and MgH2 particles. The partially absorbed 20 °C and 200 °C microstructures both show this morphology. TEM results combined with Johnson–Mehl–Avrami-type kinetic analysis point to the surface catalyst distribution and stability against coarsening as being a key influence on the two-stage hydriding kinetics. Remarkably, the mean size of the Nb0.5V0.5H nanocrystallites stays essentially invariant throughout cycling; it is 3 nm after 45 cycles and 4 nm after 500 cycles. A mechanistic description is provided for the cycling-induced microstructural evolution in the ternary alloy as well as in the binary baselines. DA - 2012/08/27 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b2584010-fbe6-4fd1-834c-c0fa8f58f7ef ER - TY - JOUR TI - Monogalactosyldiacylglycerols, potent nitric oxide inhibitors from the marine microalga Tetraselmis chui DO - 10.1080/14786419.2012.717285 AU - Banskota, Arjun H. AU - Gallant, Pamela AU - Stefanova, Roumiana AU - Melanson, Ronald AU - O'Leary, Stephen J. B. T2 - Natural Product Research SN - 1478-6419 SN - 1478-6427 VL - 27 IS - 12 SP - 1084 EP - 1090 KW - monogalactosyldiacylglycerol; nitric oxide; Tetraselmis chui; iNOS; microalgae; galactolipid; glycolipid AB - Methanolic extracts of some marine and freshwater microalgae were tested for their nitric oxide (NO) inhibitory activity on lipopolysaccharide-induced NO production in RAW264.7 macrophage cells. Among the tested extracts, Tetraselmis chui extract showed the strongest NO inhibitory activity, thus selected for further study. NO inhibitory activity guided isolation led to identification of two monogalactosyldiacylglycerols (MGDGs) (2S)-1-O-(6Z,9Z,12Z,15Z-octadecatetranoyl)-2-O-(4Z,7Z,10Z,13Z-hexadecatetranoyl)-3-O-β-D-galactopyranosylglycerol (1) and (2S)-1-O-(9Z,12Z,15Z-octadecatrinoyl)-2-O-(4Z,7Z,10Z,13Z-hexadecatetranoyl)-3-O-β-D-galactopyranosylglycerol (2) from the MeOH extract of T. chui. The stereo-chemistry of 1 was elucidated by classical degradation method. MGDGs 1 and 2 showed strong NO inhibitory activity compared to NG-methyl-L-arginine acetate salt, a well known NO inhibitor used as a positive control. Isolated MGDGs suppressed NO production through down-regulation of inducible NO synthase protein. A structure activity relationship study suggested that the polyunsaturated fatty acids of the MGDGs are responsible for NO inhibition. Moreover, increasing unsaturation on the fatty acid side chains enhanced the NO inhibitory potency of the MGDGs. DA - 2012/09/14 PY - 2012 PB - Taylor & Francis Group LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e8d1d05b-874f-4d8e-a224-3b13f3a074e5 ER - TY - JOUR TI - Nitric oxide inhibitory activity of monogalactosylmonoacylglycerols from a freshwater microalgae Chlorella sorokiniana DO - 10.1080/14786419.2012.696255 AU - Banskota, Arjun H. AU - Stefanova, Roumiana AU - Gallant, Pamela AU - Osborne, Jane A. AU - Melanson, Ronald AU - O'Leary, Stephen J. B. T2 - Natural Product Research SN - 1478-6419 SN - 1478-6427 VL - 27 IS - 11 SP - 1028 EP - 1031 KW - monogalactosylmonoacylglycerol; nitric oxide; Chlorella sorokiniana; microalgae AB - Chemical investigation of the freshwater microalgae Chlorella sorokiniana led to the isolation of a new monogalactosylmonoacylglycerol, namely, (2S)-1-O-(7Z,10Z-hexadecadienoyl)-3-O-β-D-galactopyranosylglycerol (1) together with a known glycolipid (2S)-1-O-(7Z,10Z,13Z-hexadecatrienoyl)-3-O-β-D-galactopyranosylglycerol (2). Both monogalactosylmonoacylglycerols showed dose-dependent nitric oxide (NO) inhibitory activity against lipopolysaccharide-induced NO production in RAW264.7 macrophage cells suggesting their possible use as anti-inflammatory agents. DA - 2012/06/18 PY - 2012 PB - Taylor & Francis Group LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 593afa4e-0433-4387-bbaf-45a99fcccca0 ER - TY - JOUR TI - Linear friction welding of a near-β titanium alloy DO - 10.1016/j.actamat.2011.04.037 AU - Dalgaard, E. AU - Wanjara, P. AU - Gholipour, J. AU - Cao, X. AU - Jonas, J. J. T2 - Acta Materialia SN - 1359-6454 SN - 1873-2453 VL - 60 IS - 2 SP - 770 EP - 780 KW - Linear friction welding; Ti-5553; Microstructure; Tensile properties AB - The linear friction welding (LFW) behaviour of near-β titanium alloy Ti–5Al–5V–5Mo–3Cr (Ti-5553) was investigated by varying the processing conditions of frequency and axial pressure. The examined mechanical properties of the welded material included microhardness and tensile properties. The maximum strains experienced by the material during LFW for each set of welding parameters were estimated based on the process parameters and then evaluated using Aramis, a three-dimensional optical deformation measurement system. The LFWed Ti-5553 was examined with electron backscatter diffraction techniques to relate the texture and phase changes to the thermomechanical conditions. Characterisation of the welds included analysis of the microstructural features of the weld region and the thermomechanically affected zone in relation to the parent material. DA - 2012/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c022a82a-fbab-4c11-a197-4792b9e81514 ER - TY - JOUR TI - Improve accuracy and sensibility in glycan structure prediction by matching glycan isotope abundance DO - 10.1016/j.aca.2012.07.009 AU - Xu, Guang AU - Liu, Xin AU - Liu, Qing yan AU - Zhou, Yanhong AU - Li, Jianjun T2 - Analytica Chimica Acta VL - 743 SP - 80 EP - 89 KW - Bioinformatics; Glycan; Isotope; Mass spectrometry AB - Mass Spectrometry (MS) is a powerful technique for the determination of glycan structures and is capable of providing qualitative and quantitative information. Recent development in computational method offers an opportunity to use glycan structure databases and de novo algorithms for extracting valuable information from MS or MS/MS data. However, detecting low-intensity peaks that are buried in noisy data sets is still a challenge and an algorithm for accurate prediction and annotation of glycan structures from MS data is highly desirable. The present study describes a novel algorithm for glycan structure prediction by matching glycan isotope abundance (mGIA), which takes isotope masses, abundances, and spacing into account. We constructed a comprehensive database containing 808 glycan compositions and their corresponding isotope abundance. Unlike most previously reported methods, not only did we take into count the m/z values of the peaks but also their corresponding logarithmic Euclidean distance of the calculated and detected isotope vectors. Evaluation against a linear classifier, obtained by training mGIA algorithm with datasets of three different human tissue samples from Consortium for Functional Glycomics (CFG) in association with Support Vector Machine (SVM), was proposed to improve the accuracy of automatic glycan structure annotation. In addition, an effective data preprocessing procedure, including baseline subtraction, smoothing, peak centroiding and composition matching for extracting correct isotope profiles from MS data was incorporated. The algorithm was validated by analyzing the mouse kidney MS data from CFG, resulting in the identification of 6 more glycan compositions than the previous annotation and significant improvement of detection of weaker peaks compared with the algorithm previously reported. DA - 2012/09/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : de878a80-0383-480b-a7f8-14549d3e0637 ER - TY - JOUR TI - Mapping of sulfur metabolic pathway by LC Orbitrap mass spectrometry DO - 10.1016/j.aca.2012.01.050 AU - Rao, Yulan AU - McCooeye, Margaret AU - Mester, Zoltán T2 - Analytica Chimica Acta VL - 721 SP - 129 EP - 136 KW - Thiol; Yeast; LTQ-Orbitrap mass spectrometry; Oxidative stress; Metabolic study AB - For the first time a liquid chromatography method with high resolution mass spectrometric detection has been developed for the simultaneous determination all key metabolites of the sulfur pathway in yeast, including all thiolic (cysteine (Cys), homocysteine (HCys), glutathione (GSH), cysteinyl-glycine (Cys-Gly), γ-glutamyl-cysteine (Glu-Cys)) and non-thiolic compounds (methionine (Met), s-adenosyl-methionine (AdoMet), s-adenosyl-homocysteine (AdoHcy), and cystathionine (Cysta)). The developed assay also permits the speciation and selective determination of reduced, oxidized and protein bound fractions of all of the five thiols. Iodoacetic acid (IAA) was chosen as the derivatizing reagent. Thiols were extracted from sub-mg quantities of yeast using hot 75% ethanol. The detection limits were in the range of 1–12 nmol L−¹ for standard solution (high femotomole, absolute), except AdoMet (116 nmol L−¹), which was unstable. In freshly harvested yeast, most of the thiols were in the reduced forms and low levels of protein-bound GSH and Glu-Cys were found. In a selenium enriched yeast, the thiols were mainly in the oxidized forms, and a significant amount of protein-bound Cys, HCys, GSH, Cys-Gly and Glu-Cys were found. The method was also applied to the metabolic study of the adaptive response of Saccharomyces cerevisiae to hydrogen peroxide, cadmium, and arsenite, and the change in concentration of thiols in the sulfur pathway was monitored over a period of 4 h. DA - 2012/04/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4900d65e-ec86-4371-ae3b-ebe7be0593bf ER - TY - JOUR TI - Resolution-enhanced native acidic gel electrophoresis: a method for resolving, sizing, and quantifying prion protein oligomers DO - 10.1016/j.ab.2012.04.005 AU - Ladner, Carol L. AU - Wishart, David S. T2 - Analytical Biochemistry VL - 426 IS - 1 SP - 54 EP - 62 KW - Prion; Electrophoresis; Oligomer; Cross-linking AB - The formation of β-sheet-rich prion protein (PrPβ) oligomers from native or cellular PrPc is thought to be a key step in the development of prion diseases. To assist in this characterization process we have developed a rapid and remarkably high resolution gel electrophoresis technique called RENAGE (resolution-enhanced native acidic gel electrophoresis) for separating, sizing, and quantifying oligomeric PrPβ complexes. PrPβ oligomers formed via either urea/salt or acid conversion can be resolved by RENAGE into a clear set of oligomeric bands differing by just one subunit. Calibration of the size of the PrPβ oligomer bands was made possible with a cross-linked mouse PrP90–232 ladder (1- to 11-mer) generated using ruthenium bipyridyl-based photoinduced cross-linking of unmodified proteins (PICUP). This PrP PICUP ladder allowed the size and abundance of PrPβ oligomers formed from urea/salt and acid conversion to be determined. This distribution consists of 7-, 8-, 9-, 10-, and 11-mers, with the most abundant species being the 8-mer. The high-resolution separation afforded by RENAGE has allowed us to investigate distinctive size and population changes in PrPβ oligomers formed under various conversion conditions, with various construct lengths, from various species or in the presence of anti-prion compounds. DA - 2012/04/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 21d15066-140f-4893-aeff-3fd94000c3c1 ER - TY - JOUR TI - Bioactive glass 45S5 powders: effect of synthesis route and resultant surface chemistry and crystallinity on protein adsorption from human plasma DO - 10.1007/s13758-012-0041-y AU - Bahniuk, Markian S. AU - Pirayesh, Hamidreza AU - Singh, Harsh D. AU - Nychka, John A. AU - Unsworth, Larry D. T2 - Biointerphases SN - 1934-8630 SN - 1559-4106 VL - 7 IS - 1-4 SP - 1 EP - 15 AB - Despite its medical applications, the mechanisms responsible for the osseointegration of bioactive glass (45S5) have yet to be fully understood. Evidence suggests that the strongest predictor for osseointegration of bioactive glasses, and ceramics, with bone tissue as the formation of an apatitic calcium phosphate layer atop the implanted material, with osteoblasts being the main mediator for new bone formation. Most have tried to understand the formation of this apatitic calcium phosphate layer, and other bioresponses between the host and bioactive glass 45S5 using Simulated Body Fluid; a solution containing ion concentrations similar to that found in human plasma without the presence of proteins. However, it is likely that cell attachment is probably largely mediated via the adsorbed protein layer. Plasma protein adsorption at the tissue bioactive glass interface has been largely overlooked. Herein, we compare crystalline and amorphous bioactive glass 45S5, in both melt-derived as well as sol–gel forms. Thus, allowing for a detailed understanding of both the role of crystallinity and powder morphology on surface ions, and plasma protein adsorption. It was found that sol–gel 45S5 powders, regardless of crystallinity, adsorbed 3–5 times as much protein as the crystalline melt-derived counterpart, as well as a greater variety of plasma proteins. The devitrification of melt-cast 45S5 resulted in only small differences in the amount and variety of the adsorbed proteome. Surface properties, and not material crystallinity, play a role in directing protein adsorption phenomena for bioactive glasses given the differences found between crystalline melt-cast 45S5 and sol–gel derived 45S5. DA - 2012/12/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0057cbb3-296e-435a-a6c9-39b6253f34d3 ER - TY - JOUR TI - And mortality in older Chinese adults: results from the Beijing longitudinal study of aging DO - 10.1007/s12603-012-0368-6 AU - Fang, X. AU - Shi, J. AU - Song, X. AU - Mitnitski, A. AU - Tang, Z. AU - Wang, C. AU - Yu, P. AU - Rockwood, Kenneth T2 - The journal of nutrition, health & aging SN - 1279-7707 SN - 1760-4788 VL - 16 IS - 10 SP - 903 EP - 907 KW - aging; falls; fractures; frailty index; mortality AB - Objectives: Falls are well known to be associated with adverse health outcomes, especially when complicated by fracture. Falls are more common in people who are frail and readily related to several items in the frailty phenotype. Less is known about the relationship between falls and frailty defined as deficit accumulation. Our objective was to investigate the relationship between falls, fractures, and frailty based on deficit accumulation. Design: Representative cohort study, with 8 year follow-up. Setting: The Beijing Longitudinal Study of Aging (BLSA). Participants: 3,257 Chinese people aged 55+ years at baseline. Measurements: A frailty index (FI) was constructed using 33 health deficits, but excluding falls and fractures. The rates of falls, fractures and death as a function of age and the FI were analyzed. Multivariable models evaluated the relationships between frailty and the risk of recurrent falls, fractures, and mortality adjusting for age, sex, and education. Self or informant reported fall and fracture data were verified against participants’ health records. Results: Of 3,257 participants at baseline (1992), 360 people (11.1%) reported a history of falls, and 238 (7.3%) reported fractures. By eight years, 1,155 people had died (35.3%). The FI was associated with an increased risk of recurrent falls (OR=1.54; 95% confidence interval (CI)=1.34–1.76), fractures (OR=1.07; 95% CI=0.94–1.22), and death (OR=1.50, 95% CI=1.41–1.60). The FI showed a significant effect on mortality in a multivariate Cox regression model (Hazard Rate=1.29, 95% CI=1.25–1.33). When adjusted for the FI, neither falls nor fractures were associated with mortality. Conclusion: Falls and fractures were common in older Chinese adults, and associated with frailty. Only frailty was independently associated with death. DA - 2012/12/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c6f5812b-b37d-4fd2-ad57-73b76dfb7a01 ER - TY - JOUR TI - Graphene-nickel cobaltite nanocomposite asymmetrical supercapacitor with commercial level mass loading DO - 10.1007/s12274-012-0246-x AU - Wang, Huanlei AU - Holt, Chris M. B. AU - Li, Zhi AU - Tan, Xuehai AU - Amirkhiz, Babak Shalchi AU - Xu, Zhanwei AU - Olsen, Brian C. AU - Stephenson, Tyler AU - Mitlin, David T2 - Nano Research SN - 1998-0124 SN - 1998-0000 VL - 5 IS - 9 SP - 605 EP - 617 KW - Graphene; nickel cobaltite (NiCo2O4); supercapacitor; energy density; power density AB - A high performance asymmetric electrochemical supercapacitor with a mass loading of 10 mg·cm–² on each planar electrode has been fabricated by using a graphene–nickel cobaltite nanocomposite (GNCC) as a positive electrode and commercial activated carbon (AC) as a negative electrode. Due to the rich number of faradaic reactions on the nickel cobaltite, the GNCC positive electrode shows significantly higher capacitance (618 F·g-¹) than graphene–Co3O4 (340 F∙g-¹) and graphene–NiO (375 F∙g-¹) nanocomposites synthesized under identical conditions. More importantly, graphene greatly enhances the conductivity of nickel cobaltite and allows the positive electrode to charge/discharge at scan rates similar to commercial AC negative electrodes. This improves both the energy density and power density of the asymmetric cell. The asymmetric cell composed of 10 mg GNCC and 30 mg AC displayed an energy density in the range of 19.5 Wh∙kg-¹ with an operational voltage of 1.4 V. At high sweep rate, the system is capable of delivering an energy density of 7.6 Wh∙kg-¹ at a power density of about 5600 W∙kg-¹. Cycling results demonstrate that the capacitance of the cell increases to 116% of the original value after the first 1600 cycles due to a progressive activation of the electrode, and maintains 102% of the initial value after 10000 cycles DA - 2012/09/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d2dc9a79-7227-4f54-ad2f-900da68e995a ER - TY - JOUR TI - Scaling of flexural and compressive ice failure DO - 10.1115/OMAE2012-84033 AU - Jordaan, Ian AU - Taylor, Rocky AU - Derradji-Aouat, Ahmed T2 - Volume 6 : Materials Technology; Polar and Arctic Sciences and Technology; Petroleum Technology Symposium T2 - ASME Proceedings : Polar and Arctic Sciences Technology T3 - 31st International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2012), June 10-15, 2012, Rio de Janeiro, Brazil SN - 9780791844939 SP - OMAE2012-84033 SP - 589 EP - 595 KW - Ice; Failure AB - Physical model tests are a powerful means of obtaining solutions to a variety of engineering problems. The applications in hydraulics and aerospace engineering are prominent, where the use of similitude and dimensionless numbers is well developed. The first step is to understand the mechanics of the process. In the case of ice, the theory has not been developed to the same degree as in fluid mechanics. The use of scale models in test basins has often focused on resistance to ship motion and on flexural failure of the ice. This has been reasonably well addressed. The properties of the model ice have often been modified to permit scaling of flexural strength as well as elastic modulus to achieve appropriate behaviour. Extension of testing to situations where ice fails in compression or combined flexure and crushing leads to additional complication. At low rates of loading, ice creeps and also demonstrates enhanced rates of creep if the stress is sufficient to cause damage (microstructural change) in the ice. At higher rates of loading, fracture processes result in a localization of loading, and in the formation of high-pressure zones, which have their own special failure process. In the paper a review of scaled ice testing is given, with associated mechanics including flexural failure. This is followed by a discussion of the failure processes in compression and related mechanics such as creep, damage and fracture. Suggestions as to scaling of these processes are made. An important aspect that is considered is the randomness of ice loads as measured in the full scale. Modelling this aspect and determination of appropriate extreme values is discussed. The Weibull modulus is suggested as an appropriate parameter. DA - 2012/06/15 PY - 2012 PB - ASME LA - eng N1 - date on PDF supplied by author for conference does not precisely agree with website metadata. Went with PDF C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b74483b5-d84a-473b-a1db-f6e798038b12 ER - TY - JOUR TI - Applicability of non-linear versus linear fractional abundance calibration plots for the quantitative determination of triacylglycerol regioisomers by tandem mass spectrometry DO - 10.1002/rcm.6569 AU - Ramaley, Louis AU - Cubero Herrera, Lisandra AU - Melanson, Jeremy E. T2 - Rapid Communications in Mass Spectrometry SN - 09514198 VL - 27 IS - 11 SP - 1251 EP - 1259 AB - RATIONALE: Regioisomeric analysis of triacylglycerols is important in understanding lipid biochemistry and the involvement of lipids in disease and nutrition. The use of calibration plots employing fractional abundances provides a simple and rapid method for such analyses. These plots are believed to be linear, but evidence exists for non-linearity. The behavior of such plots needs to be understood to allow for proper interpretation of regioisomeric data. METHODS: Solutions of five regioisomer pairs were prepared from pure standards and used to construct calibration plots using triple-stage tandem mass spectrometry (MS³) with electrospray ionization (ESIMS³) and cationization by lithium ions. The data were taken by direct infusion with an AB SCIEX QTRAP 2000 QqLIT mass spectrometer. RESULTS: Non-linear calibration plots were observed for the four isomer pairs containing the polyunsaturated eicosapentaenoic (20:5) and docosahexaenoic (22:6) acids paired with palmitic acid (16:0) or myristic acid (14:0), while the pair including palmitic and stearic (18:0) acids provided a linear plot. A non-linear model was developed for these plots and then verified experimentally. CONCLUSIONS: The fractional abundance calibration plots used in regioisomeric analysis of triacylglycerols are intrinsically non-linear, but may appear linear if the scatter in data points obscures the curvature, if the curvature is slight, or if the response factors for the two isomers in the regioisomer pair are similar. Therefore, linearity should not be assumed for these types of measurements until confirmed experimentally. DA - 2012/04/30 PY - 2012 PB - John Wiley & Sons, Ltd LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 02a53764-9020-46d3-84bd-7da8b51f015e ER - TY - JOUR TI - Plasma protein profiles of neonatal pigs before and after suckling AU - Huang, Yanyun AU - Olson, Douglas J. AU - Gordon, John R. AU - Middleton, Dorothy M. AU - Simko, Elemir T2 - Canadian Journal of Veterinary Research SN - 0830-9000 VL - 76 IS - 1 SP - 1 EP - 7 AB - Absorption of colostral proteins ingested by neonatal piglets within 24 to 36 h after birth is generally considered to be nonselective. Nevertheless, the transfer of colostral proteins, except immunoglubulins, from gut to bloodstream after natural suckling is still poorly characterized. The purpose of this study was to investigate the changes in 2-dimensional electrophoretic plasma protein profiles of neonatal piglets before and after suckling, in order to characterize the gastrointestinal absorption of colostral proteins into the neonatal bloodstream. As expected, the most significant change in plasma after suckling is the presence of a large amount of immunoglobulin. However, while the concentration of a few proteins was mildly increased in post-suckling plasma, the evidence of absorption of colostral non-immunoglobulin proteins by neonatal piglets was not detected in this study. AB - L’absorption des protéines du colostrum ingérées par les porcelets nouveau-nés dans les 24 à 36 h suivant la naissance est généralement considérée comme étant non-sélective. Néanmoins, le transfert après la tétée des protéines du colostrum, à l’exception des immunoglobulines, de l’intestin vers le sang est pauvrement caractérisé. L’objectif de ce travail était d’étudier les changements des profils plasmatiques des protéines par électrophorèse en deux dimensions chez des porcelets nouveau-nés avant et après la tétée, afin de caractériser l’absorption gastro-intestinale des protéines du colostrum dans la circulation sanguine des nouveau-nés. Tel qu’attendu, le changement le plus significatif après la tétée est la présence d’une grande quantité d’immunoglobulines. Toutefois, alors que la concentration de quelques protéines était légèrement augmentée dans les échantillons de plasma post-tétée, aucune évidence d’absorption de protéines du colostrum autres que les immunoglobulines par les porcelets nouveau-nés ne fut détectée dans cette étude. DA - 2012/01 PY - 2012 PB - Canadian Veterinary Medical Association UR - http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3244282/ LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b1f12fa6-4f2a-4775-ad37-ba3bfa4cbec8 ER - TY - JOUR TI - Induction and identification of hexadecaploid of Pinellia ternate DO - 10.1007/s10681-012-0642-z AU - He, LiangYan AU - Ding, Zhishan AU - Jiang, Fusheng AU - Jin, Bo AU - Li, Weiping AU - Ding, Xinghong AU - Sun, Jinyue AU - Lv, Guiyuan T2 - Euphytica SN - 0014-2336 SN - 1573-5060 VL - 186 IS - 2 SP - 479 EP - 488 KW - Alkaloid; Colchicine; Flow cytometry; Hexadecaploid; Morphological characterization; Pinellia ternate AB - Pinellia ternate (Thunb.) Breit (Araceae) is an important Chinese medicinal herb. In order to obtain the hexadecaploid plants of P. ternate with improved medicinal qualities, the shoot tips from in vitro-grown plants were treated with colchicine at various concentrations for different time to double the chromosome number. We obtained highest (42.5%) frequency of morphological variation when the tips were treated with 0.1% colchicine for 48 h. The putative hexadecaploid plants showed characteristics such as larger and thicker leaves, deeper green leaf color, stouter petiole, larger stomata, lower density of stomata across the lower epidermis of leaves and increased numbers of chloroplasts per stomata guard cell. Further analysis by flow cytometry and chromosome counting confirmed seven out of 129 were hexadecaploids. Besides, the growth rate (GR) of PLBs in hexadecaploid plants was 10.49% (increase rate in 1 day), 1.6 times higher than that of octoploid plants and the alkaloid content of PLBs in hexadecaploid plants was 0.0794%, 1.8 times higher than that of octoploid plant. The results indicated that we have established a successful procedure for development and propagation of hexadecaploid of P. ternate with higher GR and alkaloid content. DA - 2012/03/09 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a260ce51-7ccf-46bf-b92f-564c775d8d64 ER - TY - JOUR TI - Design and optimization for strength and integrity of tidal turbine rotor blades DO - 10.1016/j.energy.2012.08.011 AU - Liu, Pengfei AU - Veitch, Brian T2 - Energy SN - 0360-5442 VL - 46 IS - 1 SP - 393 EP - 404 KW - Turbine structure; Turbine blade failure; Turbine design optimization; Bay of Fundy; HATT (horizontal axis tidal turbine); Renewable energy AB - Tidal turbine rotor blade fractures and failures have resulted in substantial damage and hence cost of repair and recovery. The present work presents a rotor blade design and optimization method to address the blade structural strength design problem. The generic procedure is applicable to both turbine rotors and propellers. The optimization method seeks an optimum blade thickness distribution across the span with a prescribed constant safety factor for all the blade sections. This optimization procedure serves two purposes: while maintaining the required structural strength and integrity for an ultimate inflow speed, it aims to reduce the material to a minimum and to maintain power generation efficiency or improve the hydrodynamic efficiency. The value of the chosen minimum safety factor depends on the actual working conditions of the turbine in which the sectional peak loading and frequency are used: the harsher the environment, the larger the required safety factor. An engineering software tool with both hydrodynamic and structural capabilities was required to predict the instantaneous loading acting on all the blade sections, as well as the strength of a local blade section with a given blade geometry and chosen material. A time-domain, 3D unsteady panel method was then implemented based on a marine propeller software tool and used to perform the optimization. A 3-blade 20-m tidal turbine that was prototyped in parallel with the current work for the Bay of Fundy was used as an example for optimization. The optimum thickness distribution for a required safety factor at the ultimate possible inflow speed resulted in 37.6% saving in blade material. The blade thickness and distribution as a function of a maximum inflow speed of 6 m/s is also presented. The blade material used in the example was taken as nickel–aluminium–bronze (NAB) but the procedure was developed to be applicable to propeller or turbine blades of basically any material. DA - 2012/09/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6bba48dc-a3cb-4a93-8daa-beb9d569a696 ER - TY - JOUR TI - Prototyping a series of bi-directional horizontal axis tidal turbines for optimum energy conversion DO - 10.1016/j.apenergy.2012.04.042 AU - Liu, Pengfei AU - Bose, Neil T2 - Applied Energy SN - 0306-2619 VL - 99 SP - 50 EP - 66 KW - Turbine design and optimization; Turbine aerodynamics and hydrodynamics; Bay of Fundy; HATT; Tidal turbine; Tidal power AB - A series of bi-directional horizontal axis tidal turbine (HATT) rotors was prototyped. The geometry and motion parameters of the turbine series cover a wide range of tidal turbine operating conditions targeted to the tidal flow speed probability distribution of the Bay of Fundy, NS Canada. A generic yet novel wind/tidal turbine rotor design and optimization procedure was developed and used for the optimization process. In the process, optimum annual energy production, as a benchmark, was obtained and used for comparison by taking into account both rotor hydrodynamic power production performance characteristics and annual tidal inflow speed probability distribution. The diameter of the full-scale bi-directional HATT rotor series developed is 20-m. Optimum values of various variables were obtained for maximum annual energy production. These optimum values include: uniform pitch-diameter-ratio (p/D) distributions, nominal pitch values with different curve forms of non-uniform p/D distributions, shaft rotational speeds under fixed rotor diameter, diameter at fixed tip-speed-ratio (TSR), a combination of optimum shaft speeds at corresponding inflow speeds and optimum uniform p/D distribution at a fixed rotor diameter, number of rotor blades at fixed chord length, rotor solidity at fixed number of blades, and the combination of number of blades and solidity for both optimum constant pitch distribution and optimum linear pitch distribution. For the 20-m bi-directional HATT, a substantial improvement in power coefficient Cpow was obtained, from 0.28, as a result of the primary optimization process (for both optimum uniform p/D distribution and shaft speed n), to the final maximum of 0.43. This corresponds to a 56% increase in annual energy production of 1230 MW h, from 2188 to 3418 MW h, an improved energy production equivalent to the energy generated from 600 tonnes of coal (at 2 kW h per 1 kg coal from a standard thermal power plant). The annual energy production from the optimized 20-m bi-directional HATT before the deduction of mechanical and electrical conversion loses, is 3418 MW h, equivalent to the electric energy generated from 1550 tonnes of coal. DA - 2012/05/27 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d3a6ec88-3a12-448e-8fb6-0352160104a4 ER - TY - JOUR TI - Remote ice detection equipment — RIDE DO - 10.1016/j.coldregions.2011.11.004 AU - Gagnon, R. E. AU - Groves, J. AU - Pearson, W. T2 - Cold Regions Science and Technology SN - 0165-232X VL - 72 SP - 7 EP - 16 KW - Remote ice detection; Rime and glaze ice; Icing layer thickness measurement AB - A new instrument for remote ice detection and thickness measurement is described. It incorporates two optically based technologies that give it capability to measure the thickness of clear or foggy layers of solid or liquid on surfaces. The device is capable of measurements on moving surfaces such as wind turbines, and aircraft propellers and rotors. Details of the prototype are presented along with thickness data acquired during two test programs, one study on clear ice layers where measurements were obtained from a distance of ~ 15 m and the other on foggy ice layers at a distance of approximately 13 m. DA - 2012/03/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0ca78121-1226-49f4-90f4-1f21bfb18f74 ER - TY - JOUR TI - An explanation for the Molikpaq May 12, 1986 event DO - 10.1016/j.coldregions.2012.05.009 AU - Gagnon, R. E. T2 - Cold Regions Science and Technology SN - 0165-232X VL - 82 SP - 75 EP - 93 KW - Ice-induced vibration; Lock-in; Ice spalling frequency; Molikpaq structure; Ice spalling modes; Lock-in mitigation AB - The ice crushing induced vibration and so-called lock-in behavior exhibited by the Molikpaq structure during a test case event that occurred on May 12, 1986 has been explained in terms of ice spalling, and associated sawtooth load and displacement patterns, and resonance of the coupled structure–ice system where the mass and spring constant associated with the ice sheet are variable ‘effective’ quantities that depend on the ice sheet speed. Spalling at the ice edge contact zone plays a key role since the spalling frequency is directly proportional to the speed of the ice sheet towards the structure. Two modes of spalling are described for this particular event. One mode, called system resonant capped (SRC) spalling, causes loading and displacement that is similar to classic high-amplitude sawtooth loading and displacement and occurs at spalling frequencies in the vicinity of, or less than, the resonant frequency of the structure–ice system. In the present case the SRC spalling appears to be at the system resonant frequency. The other spalling mode is lowdisplacement– amplitude erratic spalling that is characterized by temporal unevenness and unevenness in the magnitude of consecutive displacement sawteeth. This type of spalling occurs at an average spalling frequency of about 4 Hz, which is substantially higher than the SRC spalling frequency range. For the analysis rough estimates for the variation of the effective mass and effective spring constant of the ice sheet throughout a range of spalling frequency were determined numerically. This treatment predicts that, for ice with similar properties as the May 12 event at least, sawtooth loading of the structure that causes structural oscillations is inevitable when an expansive ice sheet crushes against it. Potential means of significantly reducing the amplitude of the load and displacement oscillations by influencing fundamental spalling characteristics using blade-like spall initiators installed on the structure faces at the ice level are discussed. DA - 2012/10/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2ae4a793-3929-42f3-9da9-aebe1505bf95 ER - TY - JOUR TI - Numerical simulations of a tanker collision with a bergy bit incorporating hydrodynamics, a validated ice model and damage to the vessel DO - 10.1016/j.coldregions.2012.04.006 AU - Gagnon, R. E. AU - Wang, J. T2 - Cold Regions Science and Technology SN - 0165-232X VL - 81 SP - 26 EP - 35 KW - Bergy bit collision; Numerical simulation; Ship damage AB - Numerical simulations of a collision between a loaded tanker and a bergy bit have been conducted using LSDyna ™ software. The simulations incorporated hydrodynamics, via LS-Dyna's ALE formulation, and a validated crushable foam ice model. The major portion of the vessel was treated as a rigid body and a section of the hull, located on the starboard side of the forward bow where the ice contact occurred, was modeled as typical ship grillage that could deform and sustain damage as a result of the collision. Strategies for dealing with the highly varying mesh densities needed for the simulations are discussed as well as load and pressure distribution on the grillage throughout the course of the collision. Realistic movement of the bergy bit due to the vessel's bow wave prior to contact with the ice was observed and the damage to the grillage resembled published results from actual grillage damage tests in the lab. A load measurement from the lab tests compared reasonably well with a rough estimate from the simulation. The collision eventually ruptured the hull in a ripping fashion resembling documented incidents of vessel impacts with ice masses. DA - 2012/09/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e9293405-f3c2-45b0-92e5-e79adee9233c ER - TY - JOUR TI - An explanation of ice-crushing induced vibrational lock-in using the Molikpaq May 12, 1986 event as a test case AU - Gagnon, R. E. T2 - Ice Research for a Sustainable Environment, the 21st IAHR International Symposium on Ice T2 - IAHR International Symposium on Ice T3 - 21st IAHR International Symposium on Ice (Ice Research for a Sustainable Environment), June 11-15, 2012, Dalian, China SN - 9787894370204 SP - 985 EP - 997 AB - The ice crushing induced vibration and so-called lock-in behavior exhibited by the Molikpaq structure during a test case event that occurred on May 12, 1986 has been explained in terms of ice spalling, and associated sawtooth load patterns, and resonance of the coupled structure-ice system where the mass and spring constant associated with the ice sheet are variable ‘effective’ quantities that depend on the ice sheet speed. Spalling at the ice edge contact zone plays a key role since the spalling frequency is directly proportional to the speed of the ice sheet towards the structure. Two modes of spalling are described for this particular event. One mode, called system resonant capped (SRC) spalling, causes loading that is similar to classic high-amplitude sawtooth loading and occurs at spalling frequencies in the vicinity of, or less than, the resonant frequency of the structure-ice system. In the present case the SRC spalling appears to be at the system resonant frequency. The other spalling mode is low-amplitude erratic spalling that is characterized by temporal unevenness and unevenness in the magnitude of consecutive load sawteeth. This type of spalling occurs at an average spalling frequency of about 4 Hz, which is substantially higher than the SRC spalling frequency range. For the analysis rough estimates for the variation of the effective mass and effective spring constant of the ice sheet throughout a range of spalling frequency were determined numerically. This treatment predicts that, for ice with similar properties as the May 12 event at least, sawtooth loading of the structure that cause structural oscillations are inevitable when an expansive ice sheet crushes against it. Potential means of significantly reducing the amplitude of the load oscillations by influencing fundamental spalling characteristics using blade-like spall initiators installed on the structure faces at the ice level are discussed. DA - 2012/06/15 PY - 2012 PB - Dalian University of Technology Press LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e143ad67-9d8d-42f6-8b02-468b196c34a4 ER - TY - CHAP TI - Fundamentals of membrane processes DO - 10.1061/9780784412275.ch03 AU - Kumar, Ashwani AU - Zhang, Tian C. AU - Surampalli, Roa Y. AU - Vigneswaran, Saravanamuthu AU - Tyagi, R. D. AU - Ong, Say Leong AU - Kao, C. M. T2 - Membrane Technology and Environmental Applications SN - 978-0-7844-1227-5 SN - 978-0-7844-7689-5 SP - 75 EP - 95 AB - This chapter describes all important aspects of a membrane-based separation process. After a brief introduction properties of membrane materials and their relevance for gaseous and liquid separation are described in details including the specific information relevant for gas-vapour, reverse osmosis, nanofiltration, ultrafiltration and microfiltration processes. Currently used separation models based on solution diffusion and pore flow are described for different type of membrane processes including the applicable mathematical equations. Use and potential application of Computational Fluid Dynamics techniques in developing improved products and enriching understanding of flow behaviour, has also been included. The Chapter closes with a brief description of future directions in membrane technology and its industrial applications. DA - 2012/12/31 PY - 2012 PB - American Society of Civil Engineers LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a080b729-a245-4035-8369-c4af0ff9c512 ER - TY - JOUR TI - Overexpression of AtOGG1, a DNA glycosylase/AP lyase, enhances seed longevity and abiotic stress tolerance in Arabidopsis DO - 10.1093/jxb/ers093 AU - Chen, Huhui AU - Chu, Pu AU - Zhou, Yuliang AU - Li, Yin AU - Liu, Jun AU - Dung, Yu AU - Tsang, Edward W. T. AU - Jiang, Liwen AU - Wu, Keqiang AU - Huang, Shangzhi T2 - Journal of Experimental Botany SN - 0022-0957 SN - 1460-2431 VL - 63 IS - 11 SP - 4107 EP - 4121 KW - 8-oxo-G; Abiotic stress; AtOGG1; Controlled deterioration treatment; DNA damage and repair; Seed longevity AB - Reactive oxygen species (ROS) are toxic by-products generated continuously during seed desiccation, storage, and germination, resulting in seed deterioration and therefore decreased seed longevity. The toxicity of ROS is due to their indiscriminate reactivity with almost any constituent of the cell, such as lipids, proteins, and DNA. The damage to the genome induced by ROS has been recognized as an important cause of seed deterioration. A prominent DNA lesion induced by ROS is 7,8-dihydro-8-oxoguanine (8-oxo-G), which can form base pairs with adenine instead of cytosine during DNA replication and leads to GC→TA transversions. In Arabidopsis, AtOGG1 is a DNA glycosylase/apurinic/apyrimidinic (AP) lyase that is involved in base excision repair for eliminating 8-oxo-G from DNA. In this study, the functions of AtOGG1 were elaborated. The transcript of AtOGG1 was detected in seeds, and it was strongly up-regulated during seed desiccation and imbibition. Analysis of transformed Arabidopsis protoplasts demonstrated that AtOGG1–yellow fluorescent protein fusion protein localized to the nucleus. Overexpression of AtOGG1 in Arabidopsis enhanced seed resistance to controlled deterioration treatment. In addition, the content of 8-hydroxy-2′-deoxyguanosine (8-oxo-dG) in transgenic seeds was reduced compared to wild-type seeds, indicating a DNA damage-repair function of AtOGG1 in vivo. Furthermore, transgenic seeds exhibited increased germination ability under abiotic stresses such as methyl viologen, NaCl, mannitol, and high temperatures. Taken together, our results demonstrated that overexpression of AtOGG1 in Arabidopsis enhances seed longevity and abiotic stress tolerance. DA - 2012/04/02 PY - 2012 PB - Oxford University Press LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 20f36cb1-82ef-48f5-9835-ce67c0e6ae87 ER - TY - JOUR TI - Peroxisomal Alanine : Glyoxylate Aminotransferase AGT1 is indispensable for appressorium function of the rice blast pathogen, Magnaporthe oryzae DO - 10.1371/journal.pone.0036266 AU - Bhadauria, Vijai AU - Banniza, Sabine AU - Vandenberg, Albert AU - Selvaraj, Gopalan AU - Wei, Yangdou T2 - PLoS ONE SN - 1932-6203 VL - 7 IS - 4 SP - e36266:1 EP - e36266:9 KW - Gene Expression Regulation, Fungal; Glyoxylates; Hordeum; Magnaporthe; NAD; Oryza sativa; Oxidation-Reduction; Peroxisomes; Plant Diseases; Protein Transport; Pyruvic Acid; Sequence Deletion; Surface Properties; Transaminases AB - The role of β-oxidation and the glyoxylate cycle in fungal pathogenesis is well documented. However, an ambiguity still remains over their interaction in peroxisomes to facilitate fungal pathogenicity and virulence. In this report, we characterize a gene encoding an alanine, glyoxylate aminotransferase 1 (AGT1) in Magnaporthe oryzae, the causative agent of rice blast disease, and demonstrate that AGT1 is required for pathogenicity of M. oryzae. Targeted deletion of AGT1 resulted in the failure of penetration via appressoria; therefore, mutants lacking the gene were unable to induce blast symptoms on the hosts rice and barley. This penetration failure may be associated with a disruption in lipid mobilization during conidial germination as turgor generation in the appressorium requires mobilization of lipid reserves from the conidium. Analysis of enhanced green fluorescent protein expression using the transcriptional and translational fusion with the AGT1 promoter and open reading frame, respectively, revealed that AGT1 expressed constitutively in all in vitro grown cell types and during in planta colonization, and localized in peroxisomes. Peroxisomal localization was further confirmed by colocalization with red fluorescent protein fused with the peroxisomal targeting signal 1. Surprisingly, conidia produced by the Δagt1 mutant were unable to form appressoria on artificial inductive surfaces, even after prolonged incubation. When supplemented with nicotinamide adenine dinucleotide (NAD+)+pyruvate, appressorium formation was restored on an artificial inductive surface. Taken together, our data indicate that AGT1-dependent pyruvate formation by transferring an amino group of alanine to glyoxylate, an intermediate of the glyoxylate cycle is required for lipid mobilization and utilization. This pyruvate can be converted to non-fermentable carbon sources, which may require reoxidation of NADH generated by the β-oxidation of fatty acids to NAD+ in peroxisomes. Therefore, it may provide a means to maintain redox homeostasis in appressoria. DA - 2012/04/27 PY - 2012 PB - PLoS ONE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9c310e7f-d184-4f9b-9060-a79a4a5235e7 ER - TY - JOUR TI - Fatty acid composition of developing sea buckthorn (Hippophae rhamnoides L.) Berry and the Transcriptome of the mature seed DO - 10.1371/journal.pone.0034099 AU - Fatima, Tahira AU - Snyder, Crystal L. AU - Schroeder, William R. AU - Cram, Dustin AU - Datla, Raju AU - Wishart, David AU - Weselake, Randall J. AU - Krishna, Priti T2 - PLoS ONE SN - 1932-6203 VL - 7 IS - 4 SP - e34099:1 EP - e34099:18 KW - alpha-Linolenic Acid; Base Sequence; Biosynthetic Pathways; Fatty Acids; Fatty Acids, Monounsaturated; Fruit; Gas Chromatography-Mass Spectrometry; Gene Expression Profiling; Gene Library; Hippophae; Linoleic Acid; Molecular Sequence Data; Plant Oils; RNA-Directed DNA Polymerase; Saskatchewan; Seeds; Sequence Analysis, DNA; Transcriptome AB - Background: Sea buckthorn (Hippophae rhamnoides L.) is a hardy, fruit-producing plant known historically for its medicinal and nutraceutical properties. The most recognized product of sea buckthorn is its fruit oil, composed of seed oil that is rich in essential fatty acids, linoleic (18:2ω-6) and α-linolenic (18:3ω-3) acids, and pulp oil that contains high levels of monounsaturated palmitoleic acid (16:1ω-7). Sea buckthorn is fast gaining popularity as a source of functional food and nutraceuticals, but currently has few genomic resources; therefore, we explored the fatty acid composition of Canadian-grown cultivars (ssp. mongolica) and the sea buckthorn seed transcriptome using the 454 GS FLX sequencing technology. Results: GC-MS profiling of fatty acids in seeds and pulp of berries indicated that the seed oil contained linoleic and α-linolenic acids at 33-36% and 30-36%, respectively, while the pulp oil contained palmitoleic acid at 32-42%. 454 sequencing of sea buckthorn cDNA collections from mature seeds yielded 500,392 sequence reads, which identified 89,141 putative unigenes represented by 37,482 contigs and 51,659 singletons. Functional annotation by Gene Ontology and computational prediction of metabolic pathways indicated that primary metabolism (protein>nucleic acid>carbohydrate>lipid) and fatty acid and lipid biosynthesis pathways were highly represented categories. Sea buckthorn sequences related to fatty acid biosynthesis genes in Arabidopsis were identified, and a subset of these was examined for transcript expression at four developing stages of the berry. Conclusion: This study provides the first comprehensive genomic resources represented by expressed sequences for sea buckthorn, and demonstrates that the seed oil of Canadian-grown sea buckthorn cultivars contains high levels of linoleic acid and α-linolenic acid in a close to 1:1 ratio, which is beneficial for human health. These data provide the foundation for further studies on sea buckthorn oil, the enzymes involved in its biosynthesis, and the genes involved in the general hardiness of sea buckthorn against environmental conditions. DA - 2012/04/27 PY - 2012 PB - PLoS ONE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9621c82c-7864-410b-83a3-7a45b23a10dd ER - TY - JOUR TI - Developments in signal processing and interpretation in laser tapping DO - 10.1063/1.4789066 AU - Perton, M. AU - Neron, C. AU - Blouin, A. AU - Monchalin, J.-P. T2 - Review Of Progress In Quantitative Nondestructive Evaluation T2 - AIP Conference Proceedings; 1511 T3 - The 39th Annual Review of Progress in Quantitative Nondestructive Evaluation, 15–20 July 2012, Denver, Colorado, USA VL - 32 SP - 330 EP - 336 KW - Laser-ultrasound; Laser tapping; Tapping; Disbond; Honeycomb structures AB - A novel technique, called laser-tapping, based on the thermoelastic excitation by laser like laser-ultrasonics has been previously introduced for inspecting honeycomb and foam core structures. If the top skin is delaminated or detached from the substrate, the detached layer is driven into vibration. The interpretation of the vibrations in terms of Lamb wave resonances is first discussed for a flat bottom hole configuration and then used to determine appropriate signal processing for samples such as honeycomb structures. DA - 2012/07/20 PY - 2012 PB - AIP LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a9fbd9a7-24d5-4e05-8ce9-cbe0fada4a6e ER - TY - JOUR TI - In vitro cytotoxicity and genotoxicity studies of titanium dioxide (TiO2) nanoparticles in Chinese hamster lung fibroblast cells DO - 10.1016/j.tiv.2012.12.018 AU - Hamzeh, Mahsa AU - Sunahara, Geoffrey I. T2 - Toxicology in Vitro SN - 0887-2333 VL - 27 IS - 2 SP - 864 EP - 873 KW - Nanotoxicology; Surface modification; Cell death; Oxidative stress; DNA damage; Comet assay; Flow cytometry AB - There are increasing safety concerns about the development and abundant use of nanoparticles. The unique physical and chemical characteristics of titanium dioxide (TiO2) nanoparticles result in different chemical and biological activities compared to their larger micron-sized counterparts, and can subsequently play an important role in influencing toxicity. Therefore, our objective was to investigate the cytotoxicity and genotoxicity of commercially available TiO2 nanoparticles with respect to their selected physicochemical properties, as well as the role of surface coating of these nanoparticles. While all types of tested TiO2 samples decrease cell viability in a mass-based concentration- and size-dependent manner, the polyacrylate-coated nano-TiO2 product was only cytotoxic at higher concentrations. A similar pattern of response was observed for induction of apoptosis/necrosis, and no DNA damage was detected in the polyacrylate-coated nano-TiO2 model. Given the increasing production of TiO2 nanoparticles, toxicological studies should take into account the physiochemical properties of these nanoparticles that may help researchers to develop new nanoparticles with minimum toxicity. DA - 2012/12/28 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 11d18214-7c0a-421a-ad2c-3c29b64f2d43 ER - TY - JOUR TI - Intravascular optical coherence tomography to characterize tissue deformation during angioplasty : preliminary experiments with artery phantoms DO - 10.1117/1.JBO.17.9.096015 AU - Azarnoush, Hamed AU - Vergnole, Sébastien AU - Pazos, Valérie AU - Bisaillon, Charles-Étienne AU - Boulet, Benoit AU - Lamouche, Guy T2 - Journal of Biomedical Optics SN - 1083-3668 VL - 17 IS - 9 SP - 096015-1 EP - 096015-7 KW - Angioplasty; Optical coherence tomography; Tissue characterization AB - We explored the potential of intravascular optical coherence tomography (IVOCT) to assess deformation during angioplasty balloon inflation. Using a semi-compliant balloon and artery phantoms, we considered two experimental scenarios. The goal for the first scenario was to investigate if variation in the elasticity of the structure surrounding the balloon could be sensed by IVOCT monitoring. In this scenario, we used three single-layer phantoms with various mechanical properties. Image analysis was performed to extract the inner and outer diameters of the phantoms at various pressures. The goal for the second scenario was twofold. First, we investigated the IVOCT capability to monitor a more complex balloon inflation process. The balloon was in a folded state prior to inflation. This allowed studying two stages of deformation: during balloon unfolding and during balloon expansion. Second, we investigated IVOCT capability to monitor the deformation in a three-layer phantom used to better mimic a true artery. So, not only were the IVOCT images processed to provide the inner and outer diameters of the phantom, but the layer thicknesses were also determined. In both scenarios, IVOCT monitoring revealed to be very efficient in providing relevant information about the phantom deformation during balloon inflation. DA - 2012/09/28 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2db7f483-5d2f-4494-8633-a1908cdbb24d ER - TY - JOUR TI - Improved isolation procedure for azaspiracids from shellfish, structural elucidation of azaspiracid-6, and stability studies DO - 10.1021/jf2048788 AU - Kilcoyne, Jane AU - Keogh, Adela AU - Clancy, Ger AU - LeBlanc, Patricia AU - Burton, Ian AU - Quilliam, Michael A. AU - Hess, Philipp AU - Miles, Christopher O. T2 - Journal of Agricultural and Food Chemistry SN - 0021-8561 SN - 1520-5118 VL - 60 IS - 10 SP - 2447 EP - 2455 KW - acid; stability; NMR; mass spectrometry; purification AB - Azaspiracids are a group of lipophilic polyether toxins produced by the small dinoflagellate Azadinium spinosum. They may accumulate in shellfish and can result in illnesses when consumed by humans. Research into analytical methods, chemistry, metabolism, and toxicology of azaspiracids has been severely constrained by the scarcity of high-purity azaspiracids. Consequently, since their discovery in 1995, considerable efforts have been made to develop methods for the isolation of azaspiracids in sufficient amounts and purities for toxicological studies, in addition to the preparation of standard reference materials. A seven-step procedure was improved for the isolation of azaspiracids-1–3 (1, 2, and 3) increasing recoveries 2-fold as compared to previous methods and leading to isolation of sufficiently purified azaspiracid-6 (6) for structural determination by NMR spectroscopy. The procedure, which involved a series of partitioning and column chromatography steps, was performed on 500 g of Mytilus edulis hepatopancreas tissue containing 14 mg of 1. Overall yields of 1 (52%), 2 (43%), 3 (43%), and 6 (38%) were good, and purities were confirmed by NMR spectroscopy. The structure of 6 was determined by one- and two-dimensional NMR spectroscopy and mass spectrometry. The stability of 6 relative to 1 was also assessed in three solvents in a short-term study that demonstrated the greatest stability in aqueous acetonitrile. DA - 2012/02/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9b1700a8-4a85-401a-8db3-41ae5726527e ER - TY - JOUR TI - Transcriptome profiling and methyl homeostasis of an Arabidopsis mutant deficient in S-adenosylhomocysteine hydrolase1 (SAHH1) DO - 10.1007/s11103-012-9914-1 AU - Ouyang, Bo AU - Fei, Zhangjun AU - Joung, Je-Gun AU - Kolenovsky, Allan AU - Koh, Chushin AU - Nowak, Jacek AU - Caplan, Allan AU - Keller, Wilfred A. AU - Cui, Yuhai AU - Cutler, Adrian J. AU - Tsang, Edward W. T. T2 - Plant Molecular Biology SN - 0167-4412 SN - 1573-5028 VL - 79 IS - 4-5 SP - 315 EP - 331 KW - Seedling development KW - microarray KW - S-adenosylethionine KW - methyltransferase KW - Methyl homeostasis KW - transposons KW - root hair AB - Transcriptome profiling was conducted to detect genes whose expression is significantly changed in an Arabidopsis mutant deficient in S-adenosylhomocysteine hydrolase1 (SAHH1) during early seedling development when mutant phenotypes could be clearly observed. A total of 2,040 differentially expressed genes were identified, representing approximately 6.7 % of the 30,385 DNA oligonucleotide targets on the microarray. Among these differential expressed genes, many were mapped to pathways essential to plant growth and development including those of primary, secondary and hormone metabolisms. A significant proportion of up-regulated genes encoded transposable elements which were mapped to the centromeric and pericentromeric regions of the Arabidopsis chromosomes that were analyzed. A number of down-regulated genes were found to be involved in root hair formation, which might have contributed to the root hair defective phenotype of the mutant. Analysis of genes encoding transposable elements and those associating with root hair development indicated that these genes were highly co-expressed during seedling development. Despite SAHH1 deficiency, the expression of genes encoding methyltransferase remained largely unchanged in the sahh1 mutant. Bisulfite sequencing analysis of the transposable elements and the FWA gene revealed that their sequences in the mutant were deficient of 5-methylcytosines. Analysis of mutant genomic DNA using restriction endonucleases that were unable to cut methylated DNA suggested a genome-wide hypomethylation had occurred in the mutant. These results indicated that SAHH1 plays a critical role in methyl homeostasis, and its deficiency is a major contributing factor to the change of global gene expression, metabolic pathways and activation of transposable elements in the sahh1 mutant. DA - 2012/05/04 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 082016c6-1e11-48bd-8b0e-1daa70022512 ER - TY - JOUR TI - Identification of olivetolic acid cyclase from Cannabis sativa reveals a unique catalytic route to plant polyketides DO - 10.1073/pnas.1200330109 AU - Gagne, Steve J. AU - Stout, Jake M. AU - Liu, Enwu AU - Boubakir, Zakia AU - Clark, Shawn M. AU - Page, Jonathan E. T2 - Proceedings of the National Academy of Sciences of the United States of America SN - 0027-8424 SN - 1091-6490 VL - 109 IS - 31 SP - 12811 EP - 12816 KW - Natural products KW - phytocannabinoid KW - terpenophenolic KW - aldolase KW - ferredoxin-like AB - Δ9-Tetrahydrocannabinol (THC) and other cannabinoids are responsible for the psychoactive and medicinal properties of Cannabis sativa L. (marijuana). The first intermediate in the cannabinoid biosynthetic pathway is proposed to be olivetolic acid (OA), an alkylresorcinolic acid that forms the polyketide nucleus of the cannabinoids. OA has been postulated to be synthesized by a type III polyketide synthase (PKS) enzyme, but so far type III PKSs from cannabis have been shown to produce catalytic byproducts instead of OA. We analyzed the transcriptome of glandular trichomes from female cannabis flowers, which are the primary site of cannabinoid biosynthesis, and searched for polyketide cyclase-like enzymes that could assist in OA cyclization. Here, we show that a type III PKS (tetraketide synthase) from cannabis trichomes requires the presence of a polyketide cyclase enzyme, olivetolic acid cyclase (OAC), which catalyzes a C2–C7 intramolecular aldol condensation with carboxylate retention to form OA. OAC is a dimeric α+β barrel (DABB) protein that is structurally similar to polyketide cyclases from Streptomyces species. OAC transcript is present at high levels in glandular trichomes, an expression profile that parallels other cannabinoid pathway enzymes. Our identification of OAC both clarifies the cannabinoid pathway and demonstrates unexpected evolutionary parallels between polyketide biosynthesis in plants and bacteria. In addition, the widespread occurrence of DABB proteins in plants suggests that polyketide cyclases may play an overlooked role in generating plant chemical diversity. DA - 2012/07/16 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9c367b70-3489-4456-9046-fe81197721d6 ER - TY - JOUR TI - Alanine : Glyoxylate aminotransferase 1 is required for mobilization and utilization of triglycerides during infection process of the rice blast pathogen, Magnaporthe oryzae DO - 10.4161/psb.21368 AU - Bhadauria, Vijai AU - Banniza, Sabine AU - Vandenberg, Albert AU - Selvaraj, Gopalan AU - Wei, Yangdou T2 - Plant Signaling & Behavior SN - 1559-2316 VL - 7 IS - 9 SP - 1206 EP - 1208 KW - Pathogenicity KW - conidia KW - appressorium KW - lipid KW - AGT1 AB - The rice blast pathogen, Magnaporthe oryzae has been widely used as a model pathogen to study plant infection-related fungal morphogenesis, such as penetration via appressorium and plant-microbe interactions at the molecular level. Previously, we identified a gene encoding peroxisomal alanine: glyoxylate aminotransferase 1 (AGT1) in M. oryzae and demonstrated that the AGT1 was indispensable for pathogenicity. The AGT1 knockout mutants were unable to penetrate the host plants, such as rice and barley, and therefore were non-pathogenic. The inability of ∆Moagt1 mutants to penetrate the susceptible plants was likely due to the disruption in coordination of the β-oxidation and the glyoxylate cycle resulted from a blockage in lipid droplet mobilization and eventually utilization during conidial germination and appressorium morphogenesis, respectively. Here, we further demonstrate the role of AGT1 in lipid mobilization by in vitro germination assays and confocal microscopy. DA - 2012/08/17 PY - 2012 PB - Landes Bioscience LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ad568843-c5c3-4f71-9175-30ff8f2b5b4e ER - TY - JOUR TI - Doubled haploidy as a tool in ornamental breeding DO - 10.17660/ActaHortic.2012.953.23 AU - Ferrie, A. M. R. T2 - XXIV International Eucarpia Symposium Section Ornamentals: Ornamental Breeding Worldwide T2 - Acta Horticulturae; 953 T3 - XXIV Eucarpia Symposium on Ornamentals - Ornamental Breeding Worldwide, September 2-5, 2012, Warsaw, Poland SN - 0567-7572 SN - 2406-6168 SN - 9978-90-66054-17-2 SP - 167 EP - 171 KW - Androgenesis KW - gynogenesis KW - microspore embryogenesis AB - Haploidy/doubled haploidy methodology is commonly used in many agronomically important crops to speed the development of new cultivars. There are a number of advantages in using haploidy technology in both practical application (varietal development, mutagenesis, transformation) and basic research (genomics, biochemical, and physiological studies). Haploid plants are commonly produced using one of four methods: culture of anthers or microspores (androgenesis), culture of unfertilized ovules (gynogenesis), interspecific or intergeneric crosses followed by chromosome elimination, and by pollination with irradiated pollen. The most efficient method depends on the species. In many species, the culture of isolated microspores or anthers is the most frequently used method of haploid production. With this method, every microspore is potentially capable of regenerating into a viable embryo and each plant would therefore represent the variation which exists in the population of microspores. Plant regeneration occurs either by direct embryogenesis or through callus formation followed by embryogenesis or organogenesis. There are a number of factors influencing embryogenesis from anther/microspores or ovaries/ovules including genotype, donor plant growth conditions, stage of explant development, composition of the culture medium, and environmental conditions during culture. The frequency of embryo production will depend on whether or not these conditions are optimal and varies depending on the species. Compared to some agronomic species, there has been very little work on doubled haploidy in ornamental species despite the potential benefits. DA - 2012/11/30 PY - 2012 PB - International Society for Horticultural Science LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a7776e7e-7b0e-437a-929b-fe0aa04d6b21 ER - TY - JOUR TI - Identification and quantification of Cyclolinopeptides in five flaxseed cultivars DO - 10.1021/jf301847u AU - Gui, Bo AU - Shim, Youn Young AU - Datla, Raju S. S. AU - Covello, Patrick S. AU - Stone, Sandra L. AU - Reaney, Martin J. T. T2 - Journal of Agricultural and Food Chemistry SN - 0021-8561 SN - 1520-5118 VL - 60 IS - 35 SP - 8571 EP - 8579 KW - cyclolinopeptide KW - HPLC quantification KW - flaxseed cultivars KW - environment interaction AB - Cyclolinopeptides are a group of naturally occurring hydrophobic cyclic peptides found in flaxseed and flax oil that have immunosuppressive activity. This study describes the measurement of flaxseed cyclolinopeptide concentrations using an internal standard HPLC method. In addition, the concentration of cyclolinopeptides in the seed of Canadian flax cultivars grown at two locations over two years is reported. The data are consistent with the formation of flaxseed cyclolinopeptides from two ribosome-derived precursors. Each precursor protein includes the sequences corresponding to three cyclolinopeptides from which those cyclolinopeptides are presumably derived by precursor processing. The concentrations of cyclolinopeptides C and E, which are encoded by the same gene sequence, are highly correlated, and the concentrations of cyclolinopeptides D, F, and G, which are encoded by a second gene sequence, are also highly correlated. The strong correlation between the cyclolinopeptides arising from the same gene may prove to be important in understanding how peptide concentration is controlled. Additional research may lead to approaches to improve flax either as a platform for peptide production or as a source of oil with improved drying properties and flavor. DA - 2012/08/16 PY - 2012 PB - ACS Publications LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e5a7d140-a70d-4a73-8fbe-e0eaa752dcac ER - TY - JOUR TI - Arabidopsis mutant sk156 reveals complex regulation of SPL15 in a miR156-controlled gene network DO - 10.1186/1471-2229-12-169 AU - Wei, Shu AU - Gruber, Margaret Y. AU - Yu, Bianyun AU - Gao, Ming-Jun AU - Khachatourians, George G. AU - Hegedus, Dwayne D. AU - Parkin, Isobel A. P. AU - Hannoufa, Abdelali T2 - BMC Plant Biology SN - 1471-2229 VL - 12 SP - 169:1 EP - 169:17 KW - Arabidopsis KW - Brassica napus AB - Background: The Arabidopsis microRNA156 (miR156) regulates 11 members of the SQUAMOSA PROMOTER BINDING PROTEIN LIKE (SPL) family by base pairing to complementary target mRNAs. Each SPL gene further regulates a set of other genes; thus, miR156 controls numerous genes through a complex gene regulation network. Increased axillary branching occurs in transgenic Arabidopsis overexpressing miR156b, similar to that observed in loss-of-function max3 and max4 mutants with lesions in carotenoid cleavage dioxygenases. Arabidopsis miR156b was found to enhance carotenoid levels and reproductive shoot branching when expressed in Brassica napus, suggesting a link between miR156b expression and carotenoid metabolism. However, details of the miR156 regulatory network of SPL genes related to carotenoid metabolism are not known. Results: In this study, an Arabidopsis T-DNA enhancer mutant, sk156, was identified due to its altered branching and trichome morphology and increased seed carotenoid levels compared to wild type (WT) ecovar Columbia. Enhanced miR156b expression due to the 35S enhancers present on the T-DNA insert was responsible for these phenotypes. Constitutive and leaf primodium-specific expression of a miR156-insensitive (mutated) SPL15 (SPL15m) largely restored WT seed carotenoid levels and plant morphology when expressed in sk156. The Arabidopsis native miR156-sensitive SPL15 (SPL15n) and SPL15m driven by a native SPL15 promoter did not restore the WT phenotype in sk156. Our findings suggest that SPL15 function is somewhat redundant with other SPL family members, which collectively affect plant phenotypes. Moreover, substantially decreased miR156b transcript levels in sk156 expressing SPL15m, together with the presence of multiple repeats of SPL-binding GTAC core sequence close to the miR156b transcription start site, suggested feedback regulation of miR156b expression by SPL15. This was supported by the demonstration of specific in vitro interaction between DNA-binding SBP domain of SPL15 and the proximal promoter sequence of miR156b. Conclusions: Enhanced miR156b expression in sk156 leads to the mutant phenotype including carotenoid levels in the seed through suppression of SPL15 and other SPL target genes. Moreover, SPL15 has a regulatory role not only for downstream components, but also for its own upstream regulator miR156b. DA - 2012/09/18 PY - 2012 PB - BioMed Central LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : de96105f-da4a-4e03-8227-ad2f826ee664 ER - TY - JOUR TI - MicroRNA–mediated repression of the seed maturation program during vegetative development in Arabidopsis DO - 10.1371/journal.pgen.1003091 AU - Tang, Xurong AU - Bian, Shaomin AU - Tang, Mingjuan AU - Lu, Qing AU - Li, Shengben AU - Liu, Xigang AU - Tian, Gang AU - Nguyen, Vi AU - Tsang, Edward W. T. AU - Wang, Aiming AU - Rothstein, Steven J. AU - Chen, Xuemei AU - Cui, Yuhai T2 - PLoS Genetics SN - 1553-7404 VL - 8 IS - 11 SP - e1003091:1 EP - e1003091:13 KW - allele; Arabidopsis; argonaute 1 gene; article; bioaccumulation; controlled study; gene function; gene interaction; gene isolation; gene loss; gene overexpression; gene repression; genetic code; genetic screening; PHABULOSA gene; PHAVOLUTA gene; plant gene; plant leaf; reporter gene; seed development; transgenic plant; vegetative growth; argonaute 1 protein; microRNA; microRNA 166; small untranslated RNA; unclassified drug AB - The seed maturation program only occurs during late embryogenesis, and repression of the program is pivotal for seedling development. However, the mechanism through which this repression is achieved in vegetative tissues is poorly understood. Here we report a microRNA (miRNA)–mediated repression mechanism operating in leaves. To understand the repression of the embryonic program in seedlings, we have conducted a genetic screen using a seed maturation gene reporter transgenic line in Arabidopsis (Arabidopsis thaliana) for the isolation of mutants that ectopically express seed maturation genes in leaves. One of the mutants identified from the screen is a weak allele of ARGONAUTE1 (AGO1) that encodes an effector protein for small RNAs. We first show that it is the defect in the accumulation of miRNAs rather than other small RNAs that causes the ectopic seed gene expression in ago1. We then demonstrate that overexpression of miR166 suppresses the derepression of the seed gene reporter in ago1 and that, conversely, the specific loss of miR166 causes ectopic expression of seed maturation genes. Further, we show that ectopic expression of miR166 targets, type III homeodomain-leucine zipper (HD-ZIPIII) genes PHABULOSA (PHB) and PHAVOLUTA (PHV), is sufficient to activate seed maturation genes in vegetative tissues. Lastly, we show that PHB binds the promoter of LEAFY COTYLEDON2 (LEC2), which encodes a master regulator of seed maturation. Therefore, this study establishes a core module composed of a miRNA, its target genes (PHB and PHV), and the direct target of PHB (LEC2) as an underlying mechanism that keeps the seed maturation program off during vegetative development. DA - 2012/11/29 PY - 2012 PB - PLoS Genetics LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bd28cae2-0957-414a-ab27-ed4735783941 ER - TY - JOUR TI - Genome-wide comparative analysis of Annexin superfamily in plants DO - 10.1371/journal.pone.0047801 AU - Jami, Sravan Kumar AU - Clark, Greg B. AU - Ayele, Belay T. AU - Ashe, Paula AU - Kirti, Pulugurtha Bharadwaja T2 - PLoS ONE SN - 1932-6203 VL - 7 IS - 11 SP - e47801:1 EP - e47801:14 KW - annexin gene; Arabidopsis; article; binding site; calcium binding; comparative study; gene duplication; gene identification; gene location; gene loss; gene sequence; genetic association; genetic variability; green alga; intron; molecular phylogeny; nonhuman; phylogenetic tree; plant evolution; plant gene; plant genome; protein domain; rice; structure analysis AB - Most annexins are calcium-dependent, phospholipid-binding proteins with suggested functions in response to environmental stresses and signaling during plant growth and development. They have previously been identified and characterized in Arabidopsis and rice, and constitute a multigene family in plants. In this study, we performed a comparative analysis of annexin gene families in the sequenced genomes of Viridiplantae ranging from unicellular green algae to multicellular plants, and identified 149 genes. Phylogenetic studies of these deduced annexins classified them into nine different arbitrary groups. The occurrence and distribution of bona fide type II calcium binding sites within the four annexin domains were found to be different in each of these groups. Analysis of chromosomal distribution of annexin genes in rice, Arabidopsis and poplar revealed their localization on various chromosomes with some members also found on duplicated chromosomal segments leading to gene family expansion. Analysis of gene structure suggests sequential or differential loss of introns during the evolution of land plant annexin genes. Intron positions and phases are well conserved in annexin genes from representative genomes ranging from Physcomitrella to higher plants. The occurrence of alternative motifs such as K/R/HGD was found to be overlapping or at the mutated regions of the type II calcium binding sites indicating potential functional divergence in certain plant annexins. This study provides a basis for further functional analysis and characterization of annexin multigene families in the plant lineage. DA - 2012/11/02 PY - 2012 PB - PLoS ONE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 586d8edc-ed79-423d-807c-30d9f1db7659 ER - TY - JOUR TI - Maple sap and syrup are a rich source of abscisic acid with potential benefits to health DO - 10.17660/ActaHortic.2012.939.16 AU - Desjardins, Y. AU - Ratti, C. AU - Zaharia, I. AU - Abrams, S. T2 - XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Emerging Health Topics in Fruits and Vegetables T2 - Acta Horticulturae; 939 T3 - XXVIII International Horticultural Congress (IHC2010), August 22-27, 2010, Lisbon, Portugal SN - 0567-7572 SN - 2406-6168 SN - 978-90-66056-65-7 SP - 129 EP - 136 KW - Acer saccharum KW - sugar maple KW - phytohormones KW - sap KW - syrup KW - diabetes KW - HPLC-MS AB - For centuries maple sap and syrup have been a staple of North-American native people and are consumed now-a-days throughout the world as edulcoration produce and natural sweeteners. Apart from sugar, the natural sap contains minerals, oligosaccharides, some proteins, polyphenols and phytohormones. The sap and processed syrup are rich in abscisic acid (ABA) and its oxidation metabolites phaseic acid and dihydrophaseic acid depicting a strong oxidative inactivation of ABA prior to bud break. Actually, phaseic acid and dihydrophaseic acid account for almost 90% of this class of molecules, while ABA account for less to 10% of this sesquiterpenoid in the sap and syrup. The high titer of ABA and ABA metabolites may be associated to reduction in chronic diseases. DA - 2012/11/30 PY - 2012 PB - International Society for Horticultural Science LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d41f4f8b-0ff7-4268-94fb-a9475c64fd88 ER - TY - JOUR TI - Gene expression analysis in microdissected shoot meristems of Brassica napus microspore-derived embryos with altered SHOOTMERISTEMLESS levels DO - 10.1007/s00425-012-1814-8 AU - Elhiti, Mohamed AU - Wally, Owen S. D. AU - Belmonte, Mark F. AU - Chan, Ainsley AU - Cao, Yongguo AU - Xiang, Daoquan AU - Datla, Raju AU - Stasolla, Claudio T2 - Planta SN - 0032-0935 SN - 1432-2048 VL - 237 IS - 4 SP - 1065 EP - 1082 KW - Brassica KW - gene expression KW - microarray KW - microspore-derived embryos KW - shoot apical meristem AB - Altered expression of Brassica napus (Bn) SHOOTMERISTEMLESS (STM) affects the morphology and behaviour of microspore-derived embryos (MDEs). While down-regulation of BnSTM repressed the formation of the shoot meristem (SAM) and reduced the number of Brassica MDEs able to regenerate viable plants at germination, over-expression of BnSTM enhanced the structure of the SAM and improved regeneration frequency. Within dissected SAMs, the induction of BnSTM up-regulated the expression of many transcription factors (TFs) some of which directly involved in the formation of the meristem, i.e. CUP-SHAPED COTYLEDON1 and WUSCHEL, and regulatory components of the antioxidant response, hormone signalling, and cell wall synthesis and modification. Opposite expression patterns for some of these genes were observed in the SAMs of MDEs down-regulating BnSTM. Altered expression of BnSTM affected transcription of cell wall and lignin biosynthetic genes. The expression of PHENYLALANINE AMMONIA LYASE2, CINNAMATE 4-4HYDROXYLASE, and CINNAMYL ALCOHOL DEHYDROGENASE were repressed in SAMs over-expressing BnSTM. Since lignin formation is a feature of irreversible cell differentiation, these results suggest that one way in which BnSTM promotes indeterminate cell fate may be by preventing the expression of components of biochemical pathways involved in the accumulation of lignin in the meristematic cells. Overall, these studies provide evidence for a novel function of BnSTM in enhancing the quality of in vitro produced meristems, and propose that this gene can be used as a potential target to improve regeneration of cultured embryos. DA - 2012/12/15 PY - 2012 PB - Springer-Verlag LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9a6a9d9a-7e90-4859-afa5-35164147e0b9 ER - TY - JOUR TI - Overexpression of a novel biotrophy-specific colletotrichum truncatum Effector, CtNUDIX, in hemibiotrophic fungal phytopathogens causes incompatibility with their host plants DO - 10.1128/EC.00192-12 AU - Bhadauria, Vijai AU - Banniza, Sabine AU - Vandenberg, Albert AU - Selvaraj, Gopalan AU - Wei, Yangdou T2 - Eukaryotic Cell SN - 1535-9778 SN - 1535-9786 VL - 12 IS - 1 SP - 2 EP - 11 AB - The hemibiotrophic fungus Colletotrichum truncatum causes anthracnose disease on lentils and a few other grain legumes. It shows initial symptomless intracellular growth, where colonized host cells remain viable (biotrophy), and then switches to necrotrophic growth, killing the colonized host plant tissues. Here, we report a novel effector gene, CtNUDIX, from C. truncatum that is exclusively expressed during the late biotrophic phase (before the switch to necrotrophy) and elicits a hypersensitive response (HR)-like cell death in tobacco leaves transiently expressing the effector. CtNUDIX homologs, which contain a signal peptide and a Nudix hydrolase domain, may be unique to hemibiotrophic fungal and fungus-like plant pathogens. CtNUDIX lacking a signal peptide or a Nudix motif failed to induce cell death in tobacco. Expression of CtNUDIX:eGFP in tobacco suggested that the fusion protein might act on the host cell plasma membrane. Overexpression of CtNUDIX in C. truncatum and the rice blast pathogen, Magnaporthe oryzae, resulted in incompatibility with the hosts lentil and barley, respectively, by causing an HR-like response in infected host cells associated with the biotrophic invasive hyphae. These results suggest that C. truncatum and possibly M. oryzae elicit cell death to signal the transition from biotrophy to necrotrophy. DA - 2012/09/07 PY - 2012 PB - American Society of Microbiology LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : da1a6c6a-0e81-424a-ad46-f4493850c816 ER - TY - JOUR TI - The multigene family of lysophosphatidate acyltransferase (LPAT)-related enzymes in Ricinus communis. Cloning and molecular characterization of two LPAT genes that are expressed in castor seeds DO - 10.1016/j.plantsci.2012.09.015 AU - Arroyo-Caro, José María AU - Chileh, Tarik AU - Kazachkov, Michael AU - Zou, Jitao AU - Alonso, Diego López AU - García-Maroto, Federico T2 - Plant Science SN - 01689452 VL - 199-200 SP - 29 EP - 40 KW - Ricinus communis KW - castor plant KW - lipid biosythesis KW - phosphatidic acid KW - lysophosphatidate acyltransferase KW - LPAT AB - The multigene family encoding proteins related to lysophosphatidyl-acyltransferases (LPATs) has been analyzed in the castor plant Ricinus communis. Among them, two genes designated RcLPAT2 and RcLPATB, encoding proteins with LPAT activity and expressed in the developing seed, have been cloned and characterized in some detail. RcLPAT2 groups with well characterized members of the so-called A-class LPATs and it shows a generalized expression pattern in the plant and along seed development. Enzymatic assays of RcLPAT2 indicate a preference for ricinoleoyl-CoA over other fatty acid thioesters when ricinoleoyl-LPA is used as the acyl acceptor, while oleoyl-CoA is the preferred substrate when oleoyl-LPA is employed. RcLPATB groups with B-class LPAT enzymes described as seed specific and selective for unusual fatty acids. However, RcLPATB exhibit a broad specificity on the acyl-CoAs, with saturated fatty acids (12:0–16:0) being the preferred substrates. RcLPATB is upregulated coinciding with seed triacylglycerol accumulation, but its expression is not restricted to the seed. These results are discussed in the light of a possible role for LPAT isoenzymes in the channelling of ricinoleic acid into castor bean triacylglycerol. DA - 2012/11/10 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 72c6cef3-50fd-4784-81ca-c93af2d687ac ER - TY - JOUR TI - Stable and recyclable Au25 clusters for the reduction of 4-nitrophenol DO - 10.1039/c2cc37205c AU - Shivhare, Atal AU - Ambrose, Stephen J. AU - Zhang, Haixia AU - Purves, Randy W. AU - Scott, Robert W. J. T2 - Chemical Communications SN - 1359-7345 SN - 1364-548X VL - 49 IS - 3 SP - 276 KW - 4 nitrophenol KW - gold KW - thiol derivative KW - article KW - catalyst KW - chemical reaction KW - reaction analysis KW - reduction KW - structure analysis AB - Thiol-stabilized Au₂₅L₁₈ monolayer protected clusters (MPCs) were found to be active for the reduction of 4-nitrophenol. Results suggest that these MPCs are stable catalysts and do not lose their structural integrity during the catalytic process. High stability under the reaction conditions enables the recyclability of these MPCs. DA - 2012/11/13 PY - 2012 PB - RSC Publishing LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8ab4c10a-372c-4c8a-a732-1ece1b3796bc ER - TY - JOUR TI - Involvement of Arabidopsis acyl-coenzyme A desaturase-like2 (At2g31360) in the biosynthesis of the very-long-chain monounsaturated fatty acid components of membrane lipids DO - 10.1104/pp.112.202325 AU - Smith, Mark A. AU - Dauk, Melanie AU - Ramadan, Hussein AU - Yang, Hui AU - Seamons, Laura E. AU - Haslam, Richard P. AU - Beaudoin, Frédéric AU - Ramirez-Erosa, Irving AU - Forseille, Li T2 - Plant Physiology SN - 0032-0889 SN - 1532-2548 VL - 161 IS - 1 SP - 81 EP - 96 AB - The Arabidopsis (Arabidopsis thaliana) acyl-coenzyme A (CoA) desaturase-like (ADS) gene family contains nine genes encoding fatty acid desaturase-like proteins. The biological function of only one member of the family, fatty acid desaturase5 (AtADS3/ FAD5, At3g15850), is known, and this gene encodes the plastidic palmitoyl-monogalactosyldiacylglycerol D7 desaturase. We cloned seven members of the gene family that are predicted not to have a chloroplast transit peptide and expressed them in the yeast Saccharomyces cerevisiae. All seven have previously undescribed desaturase activity on very-long-chain fatty acid (VLCFA) substrates and exhibit diverse regiospecificity, catalyzing introduction of double bonds relative to the methyl end of the molecule (n-x) at n-6 (AtADS4, At1g06350), n-7 (AtADS1.3, At1g06100 and AtADS4.2, At1g06360), n-9 (AtADS1, At1g06080 and AtADS2, At2g31360) or D9 (relative to the carboxyl end of the molecule) positions (AtADS1.2, At1g06090 and AtADS1.4, At1g06120). Through forward and reverse genetics it was shown that AtADS2 is involved in the synthesis of the 24:1(n-9) and 26:1(n-9) components (X:Y, where X is chain length and Y is number of double bonds) of seed lipids, sphingolipids, and the membrane phospholipids phosphatidylserine, and phosphatidylethanolamine. Plants deficient in AtADS2 expression showed no obvious phenotype when grown under normal growing conditions, but showed an almost complete loss of phosphatidylethanolamine (42:4), phosphatidylserine(42:4), dihydroxy-monohexosylceramide(42:2)-2, trihydroxy-monohexosylceramide(42:2)-3, and trihydroxy-glycosylinositolphosphoceramide(42:2)-3, lipid species that contain the VLCFA 24:1(n-9), and trihydroxyglycosylinositolphosphoceramide(44:2)-3, a lipid containing 26:1(n-9). Acyl-CoA profiling of these plants revealed a major reduction in 24:1-CoA and a small reduction in 26:1-CoA. Overexpression of AtADS2 resulted in a substantial increase in the percentage of glycerolipid and sphingolipids species containing 24:1 and a dramatic increase in the percentage of very-long-chain monounsaturated fatty acids in the acyl-CoA pool. Plants deficient in AtADS1 expression had reduced levels of 26:1(n-9) in seed lipids, but no significant changes in leaf phospholipids or sphingolipids were observed. These findings indicate that the 24-carbon and 26-carbon monounsaturated VLCFAs of Arabidopsis result primarily from VLCFA desaturation, rather than by elongation of long chain monounsaturated fatty acids. DA - 2012/11 PY - 2012 PB - American Society of Plant Biologists LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f7ebfa08-e21f-4931-80cc-9d853d28810d ER - TY - JOUR TI - Differential metabolite profiles and salinity tolerance between two genetically related brown-seeded and yellow-seeded Brassica carinata lines DO - 10.1016/j.plantsci.2012.09.011 AU - Canam, Thomas AU - Li, Xiang AU - Holowachuk, Jennifer AU - Yu, Min AU - Xia, Jianguo AU - Mandal, Rupasri AU - Krishnamurthy, Ramanarayan AU - Bouatra, Souhaila AU - Sinelnikov, Igor AU - Yu, Bianyun AU - Grenkow, Larry AU - Wishart, David S. AU - Steppuhn, Harold AU - Falk, Keven C. AU - Dumonceaux, Tim J. AU - Gruber, Margaret Y. T2 - Plant Science SN - 01689452 VL - 198 SP - 17 EP - 26 KW - Biorefinery KW - Brassica carinata KW - Ethiopian mustard KW - marginal land KW - Na₂SO₄ tolerance KW - stress metabolism AB - Brassica carinata (Ethiopian mustard) has previously been identified as a potential crop species suitable for marginal land in the North American prairies due to its relatively high salt tolerance. Two genetically related B. carinata lines with brown-seeded (BS) and yellow-seeded (YS) phenotypes were assessed for their tolerance to sodium sulfate. Specifically, each line was greenhouse-grown under 0, 50 and 100 mM of salt, and analyzed after four weeks and eight weeks of treatment. Generally, the height of the BS line was greater than the YS line under both salt treatments, indicating enhanced salt tolerance of the BS line. NMR-based metabolite profiling and PCA analyses indicated a more pronounced shift in key stem metabolites after four weeks of treatment with the YS line compared to the BS line. For example, tryptophan and formate levels increased in the YS line after four weeks of 100 mM salt treatment, while proline and threonine levels varied uniquely compared to other metabolites of the lines. Together, the data indicate that the brown-seeded line has greater sodium tolerance than the yellow-seed line, provide clues to the biochemical underpinnings for the phenotypic variation, and highlight the utility of B. carinata as a biorefinery crop for saline land. DA - 2012/10/04 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 16378d0c-cf76-4ab5-91f1-7901940bcb5a ER - TY - JOUR TI - Evaluation of macrozone dimensions by ultrasound and EBSD techniques DO - 10.1016/j.matchar.2012.09.011 AU - Moreau, André AU - Toubal, Lotfi AU - Bocher, Philippe AU - Humbert, Michel AU - Uta, Elena AU - Gey, Nathalie T2 - Materials Characterization SN - 1044-5803 VL - 75 SP - 115 EP - 128 KW - Macrozone; Ultrasound; Titanium; EBSD; Texture; Correlation AB - Titanium alloys are known to have texture heterogeneities, i.e. regions much larger than the grain dimensions, where the local orientation distribution of the grains differs from one region to the next. The electron backscattering diffraction (EBSD) technique is the method of choice to characterize these macro regions, which are called macrozones. Qualitatively, the images obtained by EBSD show that these macrozones may be larger or smaller, elongated or equiaxed. However, often no well-defined boundaries are observed between the macrozones and it is very hard to obtain objective and quantitative estimates of the macrozone dimensions from these data. In the present work, we present a novel, non-destruction ultrasonic technique that provides objective and quantitative characteristic dimensions of the macrozones. The obtained dimensions are based on the spatial autocorrelation function of fluctuations in the sound velocity. Thus, a pragmatic definition of macrozone dimensions naturally arises from the ultrasonic measurement. This paper has three objectives: 1) to disclose the novel, non-destructive ultrasonic technique to measure macrozone dimensions; 2) to propose a quantitative and objective definition of macrozone dimensions adapted to and arising from the ultrasonic measurement, and which is also applicable to the orientation data obtained by EBSD; and 3) to compare the macrozone dimensions obtained using the two techniques on two samples of the near-alpha titanium alloy IMI834. In addition, it was observed that macrozones may present a semi-periodical arrangement. DA - 2012/10/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0b58f002-11e3-45a3-98c8-985d41c46b69 ER - TY - JOUR TI - Poly(arylene ether) electrolyte membranes bearing aliphatic-chain-linked sulfophenyl pendant groups DO - 10.1016/j.memsci.2012.08.044 AU - Zhang, Qiang AU - Liu, Baijun AU - Hu, Wei AU - Xu, Wan AU - Jiang, Zhenhua AU - Xing, Wei AU - Guiver, Michael D. T2 - Journal of Membrane Science SN - 0376-7388 VL - 428 SP - 629 EP - 638 KW - Poly(arylene ether)s; Proton exchange membranes; Morphology; Fuel cells AB - Two series of novel side-chain-acid poly(arylene ether)s bearing aliphatic-chain-linked sulfophenyl pendants are synthesized by direct polycondensation reactions derived from a new sulfonated difluoro-monomer, sodium 4-(3--(4-(2,6-difluorobenzoyl)phenoxy)propoxy)benzenesulfonate. The sulfonation content is readily controlled by adjusting the feed ratios of sulfonated and unsulfonated monomers. The obtained polymers exhibit considerably reduced dimensional swelling and good proton conductivities. It is found that the cyano-functionalized poly(arylene ether)s exhibit lower water uptake and dimensional swelling in comparison with the corresponding SPAE series. SPAEK-3 with an ion exchange capacity of 1.5 mequiv g(-1) has proton conductivity of 0.12 S cm(-1) and water swelling ratio of only 26% at 100 degrees Celsius. Importantly, obvious hydrophobic/hydrophilic phase separation morphology is observed, which may be highly related with their good proton transport ability. DA - 2012/09/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a20f3951-0ad4-4bd2-8596-3912efac8bfb ER - TY - JOUR TI - Performance and stability of proton conducting solid oxide fuel cells based on yttrium-doped barium cerate-zirconate thin-film electrolyte DO - 10.1016/j.jpowsour.2012.11.094 AU - Yoo, Yeong AU - Lim, Nguon T2 - Journal of Power Sources SN - 0378-7753 VL - 229 SP - 48 EP - 57 KW - Yttrium-doped barium cerate-zirconate; Proton conducting SOFCs; Stability; Thin-film electrolyte; Reversible SOFCs AB - The high performance anode supported single cells, comprising of BSCF (Ba0.5Sr0.5Co0.8Fe0.2O3−δ)-BCZY (Ba0.98Ce0.6Zr0.2Y0.2O3−δ)//BCZY//NiO–BCZY have been fabricated by wet powder spraying and co-firing for depositing 10–15 μm thin film electrolytes on pre-sintered NiO–BCZY anode discs. The open circuit voltages of single cells were around 1.12–1.13 V at 600 °C indicating negligible gas leakage or mixed conduction through the electrolyte. The maximum power density of 493 mW cm−2 was obtained at 600 °C and 0.7 V under humid air as the oxidant gas and humid 75% H2 in N2 (2.76% H2O) as the fuel gas at a gas flow rate of 100 ml min−1. The area specific resistance of an anode supported button cell of BSCF–BCZY//BCZY//NiO–BCZY in fuel cell mode was about 0.46 Ω cm2 and in the electrolysis mode was 0.26 Ω cm2 at 600 °C, indicating high efficiency, reversible SOFCs. The single cell performance was stable for over 600 h at 600 °C. The stability of BCZY electrolyte in water-containing atmospheres was investigated by exposing sintered BCZY pellets to humid air (2.76% H2O) at 200 °C for 24 h or soaking them in boiling water for 3 h. DA - 2012/11/30 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6d3fd6e1-4614-47a5-ae8e-84dbda810335 ER - TY - JOUR TI - A clustered sulfonated poly(ether sulfone) based on a new fluorene-based bisphenol monomer DO - 10.1039/c2jm34414a AU - Wang, Chenyi AU - Shin, Dong Won AU - Lee, So Young AU - Kang, Na Rae AU - Robertson, Gilles P. AU - Lee, Young Moo AU - Guiver, Michael D. T2 - Journal of Materials Chemistry SN - 0959-9428 SN - 1364-5501 VL - 22 IS - 48 SP - 25093 EP - 25101 AB - A new fluorene-based bisphenol monomer containing two pendant phenyl groups, 9,9-bis(3-phenyl-4-hydroxy)phenyl-fluorene, was readily synthesized in high yield by a one-step reaction from inexpensive starting materials. A series of poly(ether sulfone)s with clustered sulfonic acid groups was prepared for fuel cell applications by polycondensation of the new monomer with bis(4-hydroxyphenyl)sulfone and bis(4-fluorophenyl)sulfone, followed by sulfonation exclusively on the fluorene rings and pendant phenyl rings, using concentrated sulfuric acid at room temperature. The sulfonated polymers gave tough, flexible, and transparent membranes by solvent casting. The ionic exchange capacity (IEC), water-uptake, dimensional stabilities, mechanical properties, thermal and oxidative stabilities as well as proton conductivities and single fuel cell properties of the membranes were investigated. The membranes with high IEC values show high proton transport properties, and their proton conductivities exhibit lower dependence on relative humidity compared with typical aromatic ion exchange membranes. 4-SPES-38 with an IEC value of 2.23 mequiv. g−1 displays comparable fuel cell performance with Nafion 212 under low humidity conditions. DA - 2012/10/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 61ea2894-0650-4c03-bd9f-08052f5a6a61 ER - TY - JOUR TI - Morphological transformation during cross-linking of a highly sulfonated poly(phenylene sulfide nitrile) random copolymer DO - 10.1039/c2ee21992a AU - Lee, So Young AU - Kang, Na Rae AU - Shin, Dong Won AU - Lee, Chang Hyun AU - Lee, Kwan-Soo AU - Guiver, Michael D. AU - Li, Nanwen AU - Lee, Young Moo T2 - Energy and Environmental Science SN - 1754-5692 SN - 1754-5706 VL - 5 IS - 12 SP - 9795 EP - 9802 AB - We present a new approach of morphological transformation for effective proton transport within ionomers, even at partially hydrated states. Highly sulfonated poly(phenylene sulfide nitrile) (XESPSN) random network copolymers were synthesized as alternatives to state-of-the-art perfluorinated polymers such as Nafion®. A combination of thermal annealing and cross-linking, which was conducted at 250 °C by simple trimerisation of ethynyl groups at the chain termini, results in a morphological transformation. The resulting nanophase separation between the hydrophilic and hydrophobic domains forms well-connected hydrophilic nanochannels for dramatically enhanced proton conduction, even at partially hydrated conditions. For instance, the proton conductivity of XESPSN60 was 160% higher than that of Nafion® 212 at 80 °C and 50% relative humidity. The water uptake and dimensional swelling were also reduced and mechanical properties and oxidative stability were improved after three-dimensional network formation. The fuel cell performance of XESPSN membranes exhibited a significantly higher maximum power density than that of Nafion® 212 under partially hydrated environments. DA - 2012/10/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 91ae1e33-1da3-41db-b374-46a1b3270f11 ER - TY - JOUR TI - Proton-conducting membranes from poly(ether sulfone)s grafted with sulfoalkylamine DO - 10.1016/j.memsci.2012.09.040 AU - Wang, Chenyi AU - Lee, So Young AU - Shin, Dong Won AU - Kang, Na Rae AU - Lee, Young Moo AU - Guiver, Michael D. T2 - Journal of Membrane Science SN - 0376-7388 VL - 427 SP - 443 EP - 450 KW - Sulfonated polymer; High IEC values; Proton conductivity; Proton exchange membrane AB - Highly sulfonated poly(ether sulfone)s with densely populated flexible acid side chains were prepared for fuel cell applications by polycondensation of 3,3'-dihydroxybenzidine with bis(4-fluorophenyl)sulfone and 4,4′-biphenol, followed by postsulfonation using 1,4-butanesultone at room temperature. The sulfonated polymers gave tough, flexible, and transparent membranes by solvent casting. The membranes had high ion exchange capacity (IEC) values (2.47–2.95 mequiv/g) and displayed good proton conductivities in the range of 13.90–20.90×10−2 and 1.08–2.21×10−2 S/cm at 95% and 35% relative humidity (RH) (80 °C), respectively. In particular, the S-PES-55 membrane with the highest IEC value showed higher or comparable proton conductivity than that of Nafion 212 in the range of 35–95% RH. The morphologies of these membranes were investigated by TEM analysis, which exhibited well-connected hydrophilic channels due to their high IEC values and densely populated flexible acid side chains. In contrast with many reported highly sulfonated polymers, the membranes showed good dimensional stability regardless of their high IEC values. DA - 2012/09/30 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5b35ac18-dbfa-4ba2-ad4b-7321b4441ed3 ER - TY - JOUR TI - Target of Rapamycin signaling regulates metabolism, growth, and life span in Arabidopsis DO - 10.1105/tpc.112.107144 AU - Ren, Maozhi AU - Venglat, Prakash AU - Qiu, Shuqing AU - Feng, Li AU - Cao, Yongguo AU - Wang, Edwin AU - Xiang, Daoquan AU - Wang, Jinghe AU - Alexander, Danny AU - Chalivendra, Subbaiah AU - Logan, David AU - Mattoo, Autar AU - Selvaraj, Gopalan AU - Datla, Raju T2 - The Plant Cell SN - 1040-4651 SN - 1532-298X VL - 24 IS - 12 SP - 4850 EP - 4874 AB - Target of Rapamycin (TOR) is a major nutrition and energy sensor that regulates growth and life span in yeast and animals. In plants, growth and life span are intertwined not only with nutrient acquisition from the soil and nutrition generation via photosynthesis but also with their unique modes of development and differentiation. How TOR functions in these processes has not yet been determined. To gain further insights, rapamycin-sensitive transgenic Arabidopsis thaliana lines (BP12) expressing yeast FK506 Binding Protein12 were developed. Inhibition of TOR in BP12 plants by rapamycin resulted in slower overall root, leaf, and shoot growth and development leading to poor nutrient uptake and light energy utilization. Experimental limitation of nutrient availability and light energy supply in wild-type Arabidopsis produced phenotypes observed with TOR knockdown plants, indicating a link between TOR signaling and nutrition/light energy status. Genetic and physiological studies together with RNA sequencing and metabolite analysis of TOR-suppressed lines revealed that TOR regulates development and life span in Arabidopsis by restructuring cell growth, carbon and nitrogen metabolism, gene expression, and rRNA and protein synthesis. Gain- and loss-of-function Ribosomal Protein S6 (RPS6) mutants additionally show that TOR function involves RPS6-mediated nutrition and light-dependent growth and life span in Arabidopsis. DA - 2012/12/01 PY - 2012 PB - American Society of Plant Biologists LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9f836c62-8980-4aae-9d77-b34f026eadb8 ER - TY - JOUR TI - Construction of genetic linkage map and mapping of QTL for seed color in Brassica rapa DO - 10.1139/g2012-066 AU - Kebede, Berisso AU - Cheema, Kuljit AU - Greenshields, David L. AU - Li, Changxi AU - Selvaraj, Gopalan AU - Rahman, Habibur T2 - Genome SN - 0831-2796 VL - 55 IS - 12 SP - 813 EP - 823 KW - Brassica rapa KW - yellow sarson KW - seed color KW - linkage map KW - QTL mapping KW - Brassica rapa KW - yellow sarson KW - couleur des graines KW - carte génétique KW - cartographie QTL AB - A genetic linkage map of Brassica rapa L. was constructed using recombinant inbred lines (RILs) derived from a cross between yellow-seeded cultivar Sampad and a yellowish brown seeded inbred line 3-0026.027. The RILs were evaluated for seed color under three conditions: field plot, greenhouse, and controlled growth chambers. Variation for seed color in the RILs ranged from yellow, like yellow sarson, to dark brown/black even though neither parent had shown brown/black colored seeds. One major QTL (SCA9-2) and one minor QTL (SCA9-1) on linkage group (LG) A9 and two minor QTL (SCA3-1, SCA5-1) on LG A3 and LG A5, respectively, were detected. These collectively explained about 67% of the total phenotypic variance. SCA9-2 mapped in the middle of LG A9, explained about 55% phenotypic variance, and consistently expressed in all environments. The second QTL on LG A9 was ~70 cM away from SCA9-2, suggesting that independent assortment of these QTLs is possible. A digenic epistatic interaction was found between the two main effect QTL on LG A9; and the epistasis X environment interaction was nonsignificant, suggesting stability of the interaction across the environments. The QTL effect on LG A9 was validated using simple sequence repeat (SSR) markers from the two QTL regions of this LG on a B₁S₁ population (F₁ backcrossed to Sampad followed by self-pollination) segregating for brown and yellow seed color, and on their self-pollinated progenies (B₁S₂). The SSR markers from the QTL region SCA9-2 showed a stronger linkage association with seed color as compared with the marker from SCA9-1. This suggests that the QTL SCA9-2 is the major determinant of seed color in the A genome of B. rapa. AB - Une carte génétique du Brassica rapa L. a été produite à l’aide de lignées recombinantes fixées (RIL) issues d’un croisement entre un parent à graines jaunes, cultivar Sampad, et un parent à graines jaunes-brunes, la lignée 3-0026.027. Les RIL ont été évaluées pour la couleur des graines sous trois conditions : au champ, en serre et en cabinet de croissance. La couleur des graines au sein des RIL allait de jaune, comparable à yellow sarson, à brun/noir foncé bien qu’aucun des deux parents n’avaient de graines brunes/noires. Un QTL majeur (SCA9-2) et un QTL mineur (SCA9-1) ont été trouvés sur le groupe de liaison (LG) A9 et deux QTL mineurs (SCA3-1 et SCA5-1) ont été détectés sur les LG A3 et LG A5 respectivement. Collectivement, ceux-ci expliquaient environ 67 % de la variation phénotypique. SCA9-2 est situé au milieu du LG A9 et expliquait environ 55 % de la variance phénotypique de manière stable dans tous les environnements. Le second QTL sur LG A9 était à environ 70 cM de SCA9-2, ce qui suggère qu’un assortiment indépendant de ces QTL est possible. Une interaction épistatique a été constatée entre les deux QTL sur LG A9 et l’interaction épistasie X environnement n’était pas significative ce qui suggère une interaction stable entre ces deux locus au sein des différents environnements. L’effet du QTL sur LG A9 a été validé au moyen de marqueurs SSR situés à proximité des deux QTL de ce LG au sein d’une population B₁S₁ (F₁ rétrocroisée sur Sampad et suivie d’une autofécondation), laquelle était en ségrégation pour des graines brunes et jaunes, ainsi qu’au sein de sa descendance (B₁S₂). Les marqueurs SSR liés au QTL SCA9-2 ont montré une plus forte association avec la couleur des graines que le marqueur associé à SCA9-1. Cela suggère que le QTL SCA9-2 serait le principal déterminant de la couleur des graines au sein du génome A chez le B. rapa. DA - 2012/11/15 PY - 2012 PB - National Research Council Canada. Research Press LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8157ccbb-7148-44d7-ae09-d3d479f59b74 ER - TY - JOUR TI - Simulation of membrane-based CO2 capture in a coal-fired power plant DO - 10.1016/j.memsci.2012.09.044 AU - Shao, Pinghai AU - Dal-Cin, Mauro M. AU - Guiver, Michael D. AU - Kumar, Ashwani T2 - Journal of Membrane Science SN - 0376-7388 VL - 427 SP - 451 EP - 459 KW - Mebrane; Permeance; Selectivity; CO2 capture; Flue gas; Capital and operating cost; Process optimization; Power demand; Liquefaction: cost of energy AB - A two-stage membrane process is designed for CO2 capture from coal-fired power plants. Vacuum operation on the permeate side of the membrane is the preferred option to reduce the power demand for compressing the huge feed volume. The energy recovered from the CO2-depleted emission stream and the energy consumed for post-capture CO2 liquefaction are considered in this simulation study. A numerical modeling of the membrane process and a brief description on assessing both the capital and operating costs of the process are provided. It is found that the membrane area requirement is dominated by recovery of the lower concentrations of CO2 in the tail portion of the flue gas stream. Process optimizations allowing the minimal CO2 capture cost or minimal power demand indicate that current membrane technology is promising for flue gas CO2 capture, assuming a permeance of 1000 GPU and CO2/N2 selectivity of 30. The potential of membrane technology for CO2 capture was also explored by using membranes with a CO2/N2 selectivity of 50 and 200. DA - 2012/10/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9f94fafe-467a-4f4f-a5a9-6278cf2b6e2e ER - TY - JOUR TI - Ordered alloy formation for Pt3Fe/C, PtFe/C and Pt5.75Fe5.75Cuy/CO2-reduction electro-catalysts DO - 10.1016/j.electacta.2012.05.103 AU - Chen, L. AU - Bock, C. AU - Mercier, P. H. J. AU - Macdougall, B. R. T2 - Electrochimica Acta SN - 0013-4686 VL - 77 SP - 212 EP - 224 KW - PEMFCs; O2 electro-reduction catalyst; Alloy formation; Ordered alloys; Rietveld fitting AB - Carbon supported Pt3Fe, PtFe and Pt5.75Fe5.75Cu catalysts are prepared via the impregnation of Fe and/or Cu-nitrate precursor salts onto a preformed nano-sized Pt/C catalyst. They are referred to as Pt3Fe/C, PtFe/C and Pt5.75Fe5.75Cu/C catalysts and the subscripts refer to the nominal Pt, Fe and Cu atomic ratios. The final catalysts are obtained by annealing the impregnated samples in a H2 enriched atmosphere. Pt5.75Fe6.75/C, Pt5.75Cu6.75/C and Pt5.75Fe5.75Cu2/C catalysts were also made. The as-prepared catalysts are characterized using X-ray diffraction, transmission electron microscopy, standard electrochemical methods and probed for the electrochemical O2 reduction reaction (orr). Rietveld analyses reveal that [Fm-3m] Pt, cubic [Pm-3m] Pt3Fe and tetragonal [P4/mmm] PtFe structure types are made. In case of the Pt5.75Fe5.75Cu/C catalyst, a nano-sized carbon-supported single-phase catalyst of [P4/mmm] structure is found to be made at 800 °C, with Pt and Fe ordered on separate lattice planes, while Cu is distributed randomly onto both Pt and Fe atomic planes. The PtFe/C equivalent catalyst contains in addition a separate Fe phase as well as a slightly disordered [P4/mmm] phase. Pt5.75Cu6.75/C forms a disordered cubic [Fm-3m] alloy structure. The activity toward the orr was measured after 70 potential cycling, which can cause beneficial changes to the catalysts. In case of the specific orr activity, a dependence on the catalyst series is observed as follows: Pt5.75Fe5.75Cu/C [P4/mmm] > PtFe/C [P4/mmm] > Pt3Fe/C [Pm-3 m] ≈ Pt5.75Cu6.75/C [Fm-3m] > Pt/C [Fm-3m]. The highest orr mass activities are also found for the Pt5.75Fe5.75Cu/C and subsequently for the PtFe/C catalysts. Estimated orr activities are well within the range reported in the literature. In fact the specific orr activities compare to results reported for so called de-alloyed catalyst that are among the highest orr mass activities reported in the recent literature. DA - 2012/06/09 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 69876296-e62c-48b4-be13-40bf669cd810 ER - TY - JOUR TI - Poly(arylene ether sulfone) proton exchange membranes with flexible acid side chains DO - 10.1016/j.memsci.2012.02.045 AU - Wang, Chenyi AU - Shin, Dong Won AU - Lee, So Young AU - Kang, Na Rae AU - Lee, Young Moo AU - Guiver, Michael D. T2 - Journal of Membrane Science SN - 0376-7388 VL - 405-406 SP - 68 EP - 78 KW - Sulfonated poly(arylene ether sulfone); Polymer electrolyte membranes; Proton conductivity; Dimensional stability AB - New monomers containing two or four pendent methoxyphenyl groups were synthesized by bromination of bis(4-fluorophenyl)sulfone, followed by Suzuki coupling with 4-methoxybenzeneboronic acid. Copoly(arylene ether sulfone)s containing methoxypheynl groups (2-MPAES-xx and 4-MPAES-xx) based on the corresponding monomers were prepared by aromatic nucleophilic substitution (SNAr) polycondensation. After demethylation of the methoxy group to the reactive hydroxyl group, the respective side chain-type sulfonated copolymers (2-MPAES-xx and 4-MPAES-xx) were obtained by sulfobutylation. Flexible and tough membranes having good mechanical strength were obtained by solution casting of all copolymers. The sulfonated copolymers with two or four pendent sulfobutoxyphenyl groups had high proton conductivities in the range of 0.108-0.258 S/cm for 2-SPAES-xx and 0.135-0.194 S/cm for 4-SPAES-xx at 80 degrees Celsius, respectively. The methanol permeabilities of these membranes were in the range of 1.59 x 10(-7) - 4.69 x 10(-7) cm(2)/s, which is much lower than Nafion® (15.5 x 10(-7) cm(2)/s). 2-SPAES-xxand 4-SPAES-xx display comparatively better balance between proton conductivity and water swelling than the analogous poly(arylene ether sulfone)s containing pendent sulfophenyl groups. A combination of high proton conductivities, low water uptake, and low methanol permeabilities for some of the obtained copolymers indicated that they have some of the requisite properties for proton exchange membranes in fuel cell applications. DA - 2012/03/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f477fc47-775a-47f0-833d-85026b9f0c22 ER - TY - JOUR TI - Design and economics of a hybrid membrane–temperature swing adsorption process for upgrading biogas DO - 10.1016/j.memsci.2012.02.040 AU - Shao, Pinghai AU - Dal-cin, Mauro AU - Kumar, Ashwani AU - Li, Haibin AU - Singh, Davinder Paul T2 - Journal of Membrane Science SN - 0376-7388 VL - 413-414 SP - 17 EP - 28 KW - Process design and optimization; Hollow fiber membrane; Pressure ratio; Recycling; Biogas emission; Capital and operating cost; Economic analysis AB - Processing biogas from wastewater digesters allows recovery of valuable methane and reduction in green house gas emissions. A two-stage membrane process, coupled with a temperature-swing-adsorption (TSA) as pre-treatment, was designed to generate pipeline quality methane. To improve methane recovery and process energy efficiency, the non-product streams of the membrane process were recycled and the permeate of the first membrane stage was maintained at a given pressure as the driving force for second membrane stage. The membrane process design was optimized by minimizing the objective function; the overall processing cost. It was found the membrane approach excels the PSA for producing pipeline quality methane (97% purity) in terms of methane recovery, processing cost and lower emissions. A techno-economic analysis showed that the payback time for an operation processing 200 Nm(3)/h of biogas was 6.8 months. DA - 2012/03/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 95c322c7-6a0a-4d89-a4d8-99b1e01d45a3 ER - TY - JOUR TI - An experimental investigation of HCCI combustion stability using n-heptane DO - 10.1115/1.4005700 AU - Li, Hailin AU - Neill, W. Stuart AU - Chippior, Wallace L. T2 - Journal of Energy Resources Technology SN - 0195-0738 VL - 134 IS - 2 SP - 022204-1 EP - 022204-9 KW - HCCI; Combustion stability; Combustion phasing; Fuel flow rate AB - The combustion stability of a single-cylinder homogeneous charge compression ignition (HCCI) engine operated with n-heptane was experimentally investigated over a range of engine speeds (N), intake temperatures and pressures, compression ratios (CR), air/fuel ratios (AFR), and exhaust gas recirculation (EGR) rates. These parameters were varied to alter the combustion phasing from an overly advanced condition where engine knock occurred to an overly retarded condition where incomplete combustion was observed with excessive emissions of carbon monoxide (CO) and unburned hydrocarbons (UHC). The combustion stability was quantified by the coefficients of variation in indicated mean effective pressure (COVimep ) and peak cylinder pressure (COVPmax ). Cycle-to-cycle variations in the HCCI combustion behavior of this engine were shown to depend strongly on the combustion phasing, defined in this study as the crank angle position where 50% of the energy was released (CA50). In general, combustion instability increased significantly when the combustion phasing was overly retarded. The combustion phasing was limited to conditions where the COVimep was 5% or less as engine operation became difficult to control beyond this point. Based on the experimental data, the combustion phasing limit was approximately a linear function of the amount of fuel inducted in each cycle. Stable HCCI combustion could be obtained with progressively retarded combustion phasing as the fuel flow rate increased. In comparison, stable HCCI combustion was only obtained under very advanced combustion phasing for low load operating conditions. Investigation of the experimental data reveals that the cyclic variations in HCCI combustion were due to cycle-to-cycle variations in total heat release (THR). The combustion completeness of the previous cycle affected the in-cylinder bulk mixture conditions and resultant heat release process of the following engine cycle. DA - 2012/04/04 PY - 2012 PB - ASME LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2ea094e2-aff9-4434-a886-e4ce33dcf3c5 ER - TY - JOUR TI - The Chaperonin-60 universal target is a barcode for bacteria that enables de novo assembly of metagenomic sequence data DO - 10.1371/journal.pone.0049755 AU - Links, Matthew G. AU - Dumonceaux, Tim J. AU - Hemmingsen, Sean M. AU - Hill, Janet E. T2 - PLoS ONE SN - 1932-6203 VL - 7 IS - 11 SP - e49755:1 EP - e49755:10 KW - Amplicon KW - article KW - bacterial gene KW - bacterial genome KW - bacterium detection KW - cnp60 gene KW - DNA barcoding KW - Escherichia coli KW - gene sequence KW - gene targeting KW - genetic code KW - genetic identification KW - genetic organization KW - genetic variability KW - metagenomics KW - microbial community KW - nonhuman KW - pyrosequencing KW - RNA gene AB - Barcoding with molecular sequences is widely used to catalogue eukaryotic biodiversity. Studies investigating the community dynamics of microbes have relied heavily on gene-centric metagenomic profiling using two genes (16S rRNA and cpn60) to identify and track Bacteria. While there have been criteria formalized for barcoding of eukaryotes, these criteria have not been used to evaluate gene targets for other domains of life. Using the framework of the International Barcode of Life we evaluated DNA barcodes for Bacteria. Candidates from the 16S rRNA gene and the protein coding cpn60 gene were evaluated. Within complete bacterial genomes in the public domain representing 983 species from 21 phyla, the largest difference between median pairwise inter- and intra-specific distances (“barcode gap”) was found from cpn60. Distribution of sequence diversity along the ~555 bp cpn60 target region was remarkably uniform. The barcode gap of the cpn60 universal target facilitated the faithful de novo assembly of full-length operational taxonomic units from pyrosequencing data from a synthetic microbial community. Analysis supported the recognition of both 16S rRNA and cpn60 as DNA barcodes for Bacteria. The cpn60 universal target was found to have a much larger barcode gap than 16S rRNA suggesting cpn60 as a preferred barcode for Bacteria. A large barcode gap for cpn60 provided a robust target for species-level characterization of data. The assembly of consensus sequences for barcodes was shown to be a reliable method for the identification and tracking of novel microbes in metagenomic studies. DA - 2012/11/26 PY - 2012 PB - Public Library of Science LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : dd6cca30-9976-453e-9ba5-0774e230a9d5 ER - TY - JOUR TI - Enhancement of biological mass spectrometry by using separations based on changes in ion mobility (FAIMS and DMS) DO - 10.1007/s00216-012-6496-3 AU - Purves, Randy W. T2 - Analytical and Bioanalytical Chemistry SN - 1618-2642 SN - 1618-2650 VL - 405 IS - 1 SP - 35 EP - 42 KW - Bioanalytical methods KW - biological samples KW - HPLC KW - mass spectrometry KW - FAIMS KW - DMS AB - Analysis of complex biological samples for lowlevel analytes by liquid chromatography–tandem mass spectrometry (LC–MS/MS) often requires additional selectivity. Differential mobility techniques (FAIMS and DMS) have been shown to enhance LC–MS/MS analyses by separating ions in the gas-phase on a millisecond timescale by use of a mechanism that is complementary to both liquid chromatography and mass spectrometry. In this overview, a simplified description of the operation of these devices is given and an example presented that illustrates the utility of FAIMS (DMS) for solving a challenging analytical assay. Important recent advances in the field, including work with gas modifiers, are presented, along with an outlook for the technology. DA - 2012/10/28 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 16d202cb-49d8-416b-8715-53a45478a6ae ER - TY - JOUR TI - Characterization of novel Triacylglycerol Estolides from the seed oil of Mallotus philippensis and Trewia nudiflora DO - 10.1007/s11745-012-3721-y AU - Smith, Mark A. AU - Zhang, Haixia AU - Forseille, Li AU - Purves, Randy W. T2 - Lipids SN - 0024-4201 SN - 1558-9307 VL - 48 IS - 1 SP - 75 EP - 85 KW - Triacylglycerol KW - Estolide KW - Seed oil KW - Kamlolenic acid KW - Mallotus philippensis KW - Trewia nudiflora KW - Conjugated fatty acids KW - MALDI-TOF MS AB - Triacylglycerol estolides have been reported as components of the seed oil of a number of plant species and are generally associated with the presence of fatty acids containing hydroxyl groups. We have used MALDI-TOF MS to examine the intact acylglycerol species present in the seed oils of two plants that produce kamlolenic acid (18-hydroxy-D9cis,11trans,13trans-octadecatrienoic acid). Mallotus philippensis and Trewia nudiflora were both shown to produce seed oil rich in TAG-estolides. Analysis by MALDI-TOF MS/MS demonstrated that the TAG-estolides had a structure different to that previously proposed after enzymatic digestion of the oil. Acylglycerols containing up to 14 fatty acids were detected but fatty acid estolides were only present in a single position on the glycerol backbone, with predominantly non-hydroxyl fatty acids in the remaining two positions. Increased numbers of fatty acids per glycerol backbone were accounted for by the presence of fatty acid estolides containing a correspondingly greater number of fatty acids. For example, acylglycerols containing seven fatty acids had a fatty acid estolide of five fatty acids at one position on the glycerol backbone. Both capped and uncapped fatty acid estolides, with a free hydroxyl group, were present, with capped fatty acid estolides being more abundant in T. nudiflora and uncapped fatty acid estolides in M. philippensis. DA - 2012/10/02 PY - 2012 PB - Springer-Verlag LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : dcbf7d7f-3a98-46e1-a83a-0f30582180b3 ER - TY - JOUR TI - Metabolic interactions between the Lands Cycle and the Kennedy Pathway of Glycerolipid synthesis in Arabidopsis developing seeds DO - 10.1105/tpc.112.104604 AU - Wang, Liping AU - Shen, Wenyun AU - Kazachkov, Michael AU - Chen, Guanqun AU - Chen, Qilin AU - Carlsson, Anders S. AU - Stymne, Sten AU - Weselake, Randall J. AU - Zou, Jitao T2 - The Plant Cell SN - 1040-4651 SN - 1532-298X VL - 24 IS - 11 SP - 4652 EP - 4669 AB - It has been widely accepted that the primary function of the Lands cycle is to provide a route for acyl remodeling to modify fatty acid (FA) composition of phospholipids derived from the Kennedy pathway. Lysophosphatidylcholine acyltransferase (LPCAT) is an evolutionarily conserved key enzyme in the Lands cycle. In this study, we provide direct evidence that the Arabidopsis thaliana LPCATs, LPCAT1 and LPCAT2, participate in the Lands cycle in developing seeds. In spite of a substantially reduced initial rate of nascent FA incorporation into phosphatidylcholine (PC), the PC level in the double mutant lpcat1 lpcat2-2 remained unchanged. LPCAT deficiency triggered a compensatory response of de novo PC synthesis and a concomitant acceleration of PC turnover that were attributable at least in part to PC deacylation. Acyl-CoA profile analysis revealed complicated metabolic alterations rather than merely reduced acyl group shuffling from PC in the mutant. Shifts in FA stereospecific distribution in triacylglycerol of the mutant seed suggested a preferential retention of saturated acyl chains at the stereospecific numbering (sn)-1 position from PC and likely a channeling of lysophosphatidic acid, derived from PC, into the Kennedy pathway. Our study thus illustrates an intricate relationship between the Lands cycle and the Kennedy pathway. DA - 2012/11/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0b793346-d947-47c9-998d-ec5857192b44 ER - TY - JOUR TI - Regulation of Phytohormone biosynthesis and accumulation in Arabidopsis following treatment with commercial extract from the marine Macroalga Ascophyllum nodosum DO - 10.1007/s00344-012-9301-9 AU - Wally, Owen S. D. AU - Critchley, Alan T. AU - Hiltz, David AU - Craigie, James S. AU - Han, Xiumei AU - Zaharia, L. Irina AU - Abrams, Suzanne R. AU - Prithiviraj, Balakrishnan T2 - Journal of Plant Growth Regulation SN - 0721-7595 SN - 1435-8107 VL - 32 IS - 2 SP - 324 EP - 339 KW - Abscisic acid KW - arabidopsis KW - Ascosphyllum nodosum KW - Auxins KW - Cytokinins KW - gene expression KW - Phytohormones AB - Seaweeds and their extracts have been used for centuries in agriculture to improve plant growth and impart stress tolerance. There has been historical evidence that phytohormones present in seaweeds lead to these effects, but questions of this mode of action have always been raised. By quantifying phytohormones in seaweed extracts coupled with the use of phytohormone biosynthetic and insensitive mutants, we conclude that the phytohormone levels present within the extracts are insufficient to cause significant effects in plants when extracts are applied at recommended rates. However, components within seaweed extracts may modulate innate pathways for the biosynthesis of phytohormones in plants. Phytohormone profiles of plant tissue extracts were analyzed following root application of a commercial seaweed extract produced from Ascophyllum nodosum (ANE) to in vitro-grown Arabidopsis plants. We found an increase in total concentration of cytokinins (CKs), in particular, of trans-zeatin-type CKs, 24 and 96 h after ANE application, with an increase in cis-zeatintype CKs observed at 144 h. Concomitantly, increases in abscisic acid (ABA) and ABA catabolite levels were observed whereas auxin levels were reduced. Additionally, the profile of transcripts revealed that CK biosynthetic genes were upregulated, whereas the CK catabolic genes were repressed at 24 and 96 h following ANE application. Not surprisingly, the transcripts of ABA biosynthetic genes were increased whereas the auxin biosynthetic genes were repressed. These corroborated findings are the first to help explain the underlying physiological benefits derived from the application of ANE to plants. DA - 2012/11/06 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 671938c8-7421-4c98-b04f-ba826d0a4147 ER - TY - JOUR TI - Analysis of expressed sequence tags in Brassica napus cotyledons damaged by crucifer flea beetle feeding DO - 10.1139/g11-083 AU - Gruber, Margaret AU - Wu, Limin AU - Links, Matthew AU - Gjetvaj, Branimir AU - Durkin, Johnathan AU - Lewis, Christopher AU - Sharpe, Andrew AU - Lydiate, Derek AU - Hegedus, Dwayne T2 - Genome SN - 0831-2796 SN - 1480-3321 VL - 55 IS - 2 SP - 118 EP - 133 KW - Brassica napus KW - cotyledon EST representation KW - flea beetle Phyllotreta KW - host plant molecular response KW - Brassica napus KW - catalogue d'EST chez le cotylédon KW - altise des crucifères Phyllotetra KW - réponses moléculaires de l'hôte AB - The molecular basis of canola (Brassica napus L.) susceptibility to the crucifer flea beetle (FB, Phyllotreta cruciferae Goeze) was investigated by comparing transcript representation in FB-damaged and undamaged cotyledons. The B. napus cotyledon transcriptome increased and diversified substantially after FB feeding damage. Twenty-two genes encoding proteins with unknown function, six encoding proteins involved in signaling, and a gene encoding a B-box zinc finger transcription factor were moderately or strongly changed in representation with FB feeding damage. Zinc finger and calciumdependent genes formed the largest portion of transcription factors and signaling factors with changes in representation. Six genes with unknown function, one transcription factor, and one signaling gene specific to the FB-damaged library were co-represented in a FB-damaged leaf library. Out of 188 transcription factor and signaling gene families screened for “early” expression changes, 16 showed changes in expression within 8 h. Four of these early factors were zinc finger genes with representation only in the FB-damaged cotyledon. These genes are now available to test their potential at initiating or specifying cotyledon responses to crucifer FB feeding. AB - Les bases moléculaires de la susceptibilité du colza (Brassica napus L.) à l’altise des crucifères (Phyllotreta cruciferae Goeze) a été étudiée en comparant le transcriptome de cotylédons endommagés ou non par l’altise. Le transcriptome des cotylédons du B. napus s’est accru et diversifié considérablement suite aux dommages causés par l’alimentation de l’altise. Vingt-deux gènes codant pour des protéines de fonction inconnue, six codant pour des protéines impliquées dans la signalisation et un gène codant pour un facteur de transcription de type zinc finger à boîte B ont subi des changements d’expression modérés ou marqués en réponse aux dommages causés par l’altise. Les gènes à zinc finger ou régulés par le calcium ont constitué la plus grande fraction des facteurs de transcription ou de signalisation dont l’expression était altérée. Six gènes de fonction inconnue, un facteur de transcription et un facteur de signalisation étaient spécifiques de la banque produite à partir de feuilles attaqués et co-représentés au sein de cette banque. Parmi 188 familles de gènes codant pour des facteurs de transcription ou des protéines de signalisation qui ont été examinés pour des changements d’expression rapides, 16 ont présenté un changement à l’intérieur de huit heures. Quatre de ces facteurs « hâtifs » étaient des gènes à zinc finger exprimés uniquement au sein des cotylédons endommagés. Ces gènes sont maintenant disponibles pour évaluer leur rôle potentiel dans l’initiation ou la détermination des réponses à l’attaque de l’altise chez le cotylédon. DA - 2012/01/25 PY - 2012 PB - National Research Council Canada. Research Press LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e795a846-b518-4116-af47-b3f8b8e18ee6 ER - TY - JOUR TI - Aerobic mineralization of Nitroguanidine by Variovorax strain VC1 isolated from soil DO - 10.1021/es301047d AU - Perreault, Nancy N. AU - Halasz, Annamaria AU - Manno, Dominic AU - Thiboutot, Sonia AU - Ampleman, Guy AU - Hawari, Jalal T2 - Environmental Science & Technology SN - 0013-936X SN - 1520-5851 VL - 46 IS - 11 SP - 6035 EP - 6040 KW - A-carbon KW - aerobic mineralization KW - bacterial isolates KW - intermediate product KW - L-Arginine KW - nitrogen sources KW - Nitroguanidine KW - Nitrous oxide KW - reaction stoichiometry KW - reference material KW - resting cells KW - soil microcosms AB - Nitroguanidine (NQ) is an energetic materialthat is used as a key ingredient of triple-base propellants and is currently being considered as a TNT replacement in explosive formulations. NQ was efficiently degraded in aerobic microcosms when a carbon source was added. NQ persisted in unamended microcosms or under anaerobic conditions. An aerobic NQ-degrading bacterium, Variovorax strain VC1, was isolated from soil microcosms containing NQ as the sole nitrogen source. NQ degradation was inhibited in the presence of a more favorable source of nitrogen. Resting cells of VC1 degraded NQ effectively (54 μmol h⁻¹g⁻¹ protein) giving NH₃ (50.0%), nitrous oxide (N₂O) (48.5%) and CO₂ (100%). Disappearance of NQ was accompanied by the formation of a key intermediate product that we identified as nitrourea by comparison with a reference material. Nitrourea is unstable in water and suffered both biotic and abiotic decomposition to eventually give NH₃, N₂O, and CO₂. However, we were unable to detect urea. Based on products distribution and reaction stoichiometry, we suggested that degradation of NQ, O₂NN≕C(NH₂)₂, might involve initial enzymatic hydroxylation of the imine, ⋯C≕N⋯ bond, leading first to the formation of the unstable α-hydroxynitroamine intermediate, O₂NNHC(OH)-(NH₂)₂, whose decomposition in water should lead to the formation of NH₃, N₂O, and CO₂.NQ biodegradation was induced by nitroguanidine itself, L-arginine, and creatinine, all being iminic compounds containing a guanidine group. This first description of NQ mineralization by a bacterial isolate demonstrates the potential for efficient microbial remediation of NQ in soil. DA - 2012/05/07 PY - 2012 PB - ACS Publications LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 350357f8-1baf-4850-a76e-9cbba3443ef7 ER - TY - JOUR TI - Environmental characterization of military training ranges for munitions-related contaminants : understanding and minizing the environmental impacts of live-fire training DO - 10.1615/IntJEnergeticMaterialsChemProp.2012005257 AU - Thiboutot, Sonia AU - Ampleman, Guy AU - Brochu, Sylvie AU - Diaz, Emmanuela AU - Poulin, I. AU - Martel, Richard AU - Al-Hawari, Jalal AU - Sunahara, Geoffrey I. AU - Walsh, Michael R. AU - Walsh, Marianne E. AU - Jenkins, T. F. T2 - International Journal of Energetic Materials and Chemical Propulsion SN - 2150-766X VL - 11 IS - 1 SP - 17 EP - 57 KW - Characterization KW - munitions KW - unexploded ordnances KW - live fire KW - training ranges KW - environmental impact KW - deposition rate KW - munitions constituents KW - fate KW - ecotoxicology KW - hydrogeology KW - explosives KW - propellants AB - An important R&D effort was dedicated to the characterization of ranges and training areas and to the study of the environmental fate and the ecotoxicological impacts of munitions constituents in the last 20 years in Canada and the United States. Major environmental issues were identified, and the sources of munitions constituents in training ranges are better understood. Protocols were developed for collecting representative soil samples and their effective processing. In the last years, a large effort was dedicated to the measurement of the mass of munitions constituents deposited both at target impact areas and at firing positions, which led to a good estimation of source terms of contaminants. In Canadian ranges and training areas, efforts were also dedicated to characterize both surface and subsurface aquifers and geology, and detailed hydrogeological and geological mapping. All the data acquired over the last years have been used to build hazards and vulnerability maps, which can be combined to draw risk maps that represent great assets from a risk-management perspective. The next step is the development of environmentally sound solutions that will sustain military training and maintain force readiness. In order to achieve that goal, efforts are committed to the modification of actual live-firing activities to minimize their environmental adverse impacts. Finally, Canada is aiming at developing greener and insensitive munitions that will ease the environmental pressure. This paper is a summary of what has been done in North America toward understanding and minimizing the environmental footprint of munitions. DA - 2012 PY - 2012 PB - Begell House LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 31a29130-684e-4009-a39d-802e10494a53 ER - TY - JOUR TI - The substrate-bound crystal structure of a Baeyer–Villiger monooxygenase exhibits a Criegee-like conformation DO - 10.1021/ja211876p AU - Yachnin, Brahm J. AU - Sprules, Tara AU - McEvoy, Michelle B. AU - Lau, Peter C. K. AU - Berghuis, Albert M. T2 - Journal of the American Chemical Society SN - 0002-7863 SN - 1520-5126 VL - 134 IS - 18 SP - 7788 EP - 7795 KW - Active site KW - Baeyer Villiger oxidation KW - Baeyer-Villiger monooxygenases KW - bound structure KW - Carbonyl groups KW - cofactors KW - conformational change KW - cosubstrates KW - cyclic ketones KW - cyclohexanon monooxygenase KW - cyclohexanones KW - enantiospecificity KW - Oxygen atom KW - Rhodococcus sp KW - substrate-bound AB - The Baeyer–Villiger monooxygenases (BVMOs) are a family of bacterial flavoproteins that catalyze the synthetically useful Baeyer–Villiger oxidation reaction. This involves the conversion of ketones into esters or cyclic ketones into lactones by introducing an oxygen atom adjacent to the carbonyl group. The BVMOs offer exquisite regio- and enantiospecificity while acting on a wide range of substrates. They use only NADPH and oxygen as cosubstrates, and produce only NADP+ and water as byproducts, making them environmentally attractive for industrial purposes. Here, we report the first crystal structure of a BVMO, cyclohexanone monooxygenase (CHMO) from Rhodococcus sp. HI-31 in complex with its substrate, cyclohexanone, as well as NADP+ and FAD, to 2.4 Å resolution. This structure shows a drastic rotation of the NADP+ cofactor in comparison to previously reported NADP+-bound structures, as the nicotinamide moiety is no longer positioned above the flavin ring. Instead, the substrate, cyclohexanone, is found at this location, in an appropriate position for the formation of the Criegee intermediate. The rotation of NADP+ permits the substrate to gain access to the reactive flavin peroxyanion intermediate while preventing it from diffusing out of the active site. The structure thus reveals the conformation of the enzyme during the key catalytic step. CHMO is proposed to undergo a series of conformational changes to gradually move the substrate from the solvent, via binding in a solvent excluded pocket that dictates the enzyme’s chemospecificity, to a location above the flavin–peroxide adduct where catalysis occurs. DA - 2012/04/16 PY - 2012 PB - ACS Publications LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 548e63dd-952c-4f6a-b68f-da210ae95e9c ER - TY - JOUR TI - Pretreating mixed anaerobic communities from different sources : correlating the hydrogen yield with hydrogenase activity and microbial diversity DO - 10.1016/j.ijhydene.2012.05.105 AU - Pendyala, Brahmaiah AU - Chaganti, Subba Rao AU - Lalman, Jerald A. AU - Shanmugam, Saravanan R. AU - Heath, Daniel D. AU - Lau, Peter C. K. T2 - International Journal of Hydrogen Energy SN - 03603199 VL - 37 IS - 17 SP - 12175 EP - 12186 KW - Mixed anaerobic cultures KW - hydrogen KW - hydrogenase activity KW - T-RFLP KW - microbial diversity KW - pretreatment AB - In this study, granular and flocculated anaerobic mixed cultures were pretreated using heat, shock loading, acid, alkali, linoleic acid (LA) and 2-bromoethane sulphonic acid (BESA). Under mesophilic conditions (37°C) and an initial pH value of 6.0, higher H₂ yields were observed for the flocculated cultures when compared to the granular cultures. The maximum yield for granular cultures treated acid, BESA or LA were statistically the same. Butyric acid fermentation was dominant in a majority of the treated cultures. The maximum hydrogenase evolution specific activity (ESA) (124 ± 8 Ue mg VSS⁻¹) at 37°C correlated with the maximum H₂ yield for the LA treated flocculated cultures (1.69 ± 0.18 mol mol⁻¹ glucose). The microbial diversity data clearly showed that the low H₂ yield in the granular cultures was due to the lower proportion of H₂ producers. A principle component analysis (PCA) revealed that the LA treated flocculated and granular cultures were grouped together and showed more diversity in comparison to other pretreatment methods. DA - 2012/07/12 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b5dc6c4a-4f33-4012-9052-7014dfe889fa ER - TY - JOUR TI - Catalysis using gold nanoparticles decorated on nanocrystalline cellulose DO - 10.1039/C2NR11558A AU - Lam, Edmond AU - Hrapovic, Sabahudin AU - Majid, Ehsan AU - Chong, Jonathan H. AU - Luong, John H. T. T2 - Nanoscale VL - 4 IS - 3 SP - 997 EP - 1002 KW - 4-aminophenols KW - 4-Nitrophenol KW - Ammonium chloride KW - Au nanoparticle KW - Average diameter KW - Crystalline cellulose KW - Gold Nanoparticles KW - Hybrid inorganic-organic KW - Nanocrystalline cellulose KW - Product isolation AB - A novel nanocomposite was prepared by deposition of carbonate-stabilized Au nanoparticles (AuNPs) onto the surface of poly(diallyldimethyl ammonium chloride) (PDDA)-coated carboxylated nanocrystalline cellulose (NCC). The hybrid material possessed AuNPs (1.45% by weight) with an average diameter of 2.95 ± 0.06 nm. The catalytic activity of AuNP/PDDA/NCC for reducing 4-nitrophenol to 4-aminophenol was compared to other Au-supported composites. An activation energy of 69.2 kJ mol⁻¹ was obtained for the reaction. Indeed, the reaction rate constant k of (5.1 ± 0.2) x 10⁻³ s⁻¹ was comparable to the benchmark literature value obtained using AuNPs (<5 nm in diameter) decorated on a network of crystalline cellulose fibers. Our strategy promotes the use of natural resources to prepare reusable hybrid inorganic–organic materials for important reactions with facilitated product isolation/purification. DA - 2012/01/05 PY - 2012 PB - RSC Publishing LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7686bb94-36a1-49c1-9730-0bccf0d597e2 ER - TY - JOUR TI - Laser shockwave technique for characterization of nuclear fuel plate interfaces DO - 10.1063/1.4789068 AU - Perton, M. AU - Lévesque, D. AU - Monchalin, J.-P. AU - Lord, M. AU - Smith, J. A. AU - Rabin, B. H. T2 - Review of Progress in Qualitative Nondestructive Evaluation T2 - AIP Conference Proceedings; 1511 T3 - The 39th Annual Review Of Progress In Quantitative Nondestructive Evaluation, 15–20 July 2012, Denver, Colorado, USA SN - 1551-7616 SN - 978-0-7354-1130-2 SP - 345 EP - 352 KW - Laser ultrasonics; Shock waves; Adhesion testing; Nuclear fuel plate AB - The US National Nuclear Security Agency is tasked with minimizing the worldwide use of high-enriched uranium. One aspect of that effort is the conversion of research reactors to monolithic fuel plates of low-enriched uranium. The manufacturing process includes hot isostatic press bonding of an aluminum cladding to the fuel foil. The Laser Shockwave Technique (LST) is here evaluated for characterizing the interface strength of fuel plates using depleted Uranium/Mo foils. LST is a non-contact method that uses lasers for the generation and detection of large amplitude acoustic waves and is therefore well adapted to the quality assurance of this process. Preliminary results show a clear signature of well-bonded and debonded interfaces and the method is able to classify/rank the bond strength of fuel plates prepared under different HIP conditions. DA - 2012/07/15 PY - 2012 PB - AIP PB - AIP LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 42f4b5a6-9e51-4e38-95d3-975a12644ed8 ER - TY - JOUR TI - Real-time monitoring of combustion instability in a homogeneous charge compression ignition (HCCI) engine using cycle-by-cycle exhaust temperature measurements DO - 10.1115/ICEF2012-92191 AU - Gardiner, David P. AU - Neill, W. Stuart AU - Chippior, Wallace L. T2 - Proceedings of the 2012 Fall Technical Conference of the ASME Internal Combustion Engine Division (ICEF2012) T3 - ICEF2012: 2012 Fall Technical Conference of the ASME Internal Combustion Engine Division, September 23-26 2012, Vancouver, BC, Canada SP - ICEF2012-92191 SP - 657 EP - 666 AB - This paper describes an experimental study concerning the feasibility of monitoring the combustion instability levels of an HCCI engine based upon cycle-by-cycle exhaust temperature measurements. The test engine was a single cylinder, four-stroke, variable compression ratio Cooperative Fuel Research (CFR) engine coupled to an eddy current dynamometer. A rugged exhaust temerature sensor equipped with special signal processing circuitry was installed near the engine exhaust port. Reference measurements were provided by a laboratory grade, water-cooled cylinder pressure transducer. The cylinder pressure measurements were used to calculate the Coefficient of Variation of Indicated Mean Effective Pressure (COV of IMEP) for each operating condition tested. Experiments with the HCCI engine confirmed that cycle-by-cycle variations in exhaust temperature were present, and were of sufficient magnitude to be captured for processing as high fidelity signal waveforms. There was a good correlation between the variability of the exhaust temperature signal and the COV of IMEP throughout the operating range that was evaluated. The correlation was particularly strong at the low levels of COV of IMEP (2-3%), where production engines would typically operate. A real-time combustion instability signal was obtained from cycle-by-cycle exhaust temperature measurements, and used to provide feedback to the fuel injection control system. Closed loop operation of the HCCI engine was achieved in which the engine was operated as lean as possible while maintaining the COV level at or near 2.5%. DA - 2012/09/26 PY - 2012 PB - ASME LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5d9141ee-b2d3-4fa3-95b4-ebd8264614b5 ER - TY - JOUR TI - Soot formation in a laminar ethylene/air diffusion flame at pressures from 1 to 8atm DO - 10.1016/j.proci.2012.07.006 AU - Guo, Hongsheng AU - Gu, Zhongzhu AU - Thomson, Kevin A. AU - Smallwood, Gregory J. AU - Baksh, Fazil F. T2 - Proceedings of the Combustion Institute T3 - 34th International Symposium on Combustion, July 29-August 3 2012, Warsaw, Poland SN - 1540-7489 VL - 34 IS - 1 SP - 1795 EP - 1802 KW - Soot; PAH; Laminar diffusion flame; High pressure AB - The effect of pressure on soot formation in a laminar ethylene/air coflow diffusion flame was investigated by experiments and numerical simulation at pressures from 1 to 8 atm. Soot volume fraction was measured by the diffuse-light two-dimensional line-of-sight attenuation optical diagnostic method and calculated by moments model and a relatively detailed gas phase chemistry. The numerical model successfully captured the variation of soot volume fraction with increasing pressure. The detailed analysis of numerical simulation results suggests that although the rates of all soot formation sub-processes increase with increasing pressure, the rates of increase of these sub-processes differ, with that of PAH condensation being the fastest, followed by those of inception and acetylene addition, respectively. At atmosphere pressure, acetylene addition contributes most to soot formation in terms of the overall formed soot mass, while the contribution of PAH condensation significantly increases at high pressures. The variation in the soot formation mechanism is due to the different increase rates of the mole concentrations and formation of several key species that significantly affect soot inception, acetylene addition and PAH condensation. DA - 2012/07/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 271f61a1-2715-4072-92c6-9ae088bcd407 ER - TY - JOUR TI - ThermoPoD : a reliability study on active infrared thermography for the inspection of composite materials DO - 10.1007/s12206-012-0510-8 AU - Duan, Yuxia AU - Servais, Pierre AU - Genest, Marc AU - Ibarra-Castanedo, Clemente AU - Maldague, Xavier P. V. T2 - Journal of Mechanical Science and Technology SN - 1738-494X SN - 1976-3824 VL - 26 IS - 7 SP - 1985 EP - 1991 KW - CFRP; composite material; data processing; infrared thermography; PoD; reliability AB - In this study, a Probability of Detection (PoD) experimental study was carried out in the framework of a Belgian-Quebec/Canada collaborative research project called ThermoPoD. Experiments were implemented on a Carbon Fiber Reinforced Plastic (CFRP) specimen with embedded material simulating delamination. For active infrared thermography, different heating sources (optical or ultrasound), heating forms (pulsed or lock-in), and data processing methods, such as Fourier Transform, Thermal Signal Reconstruction, Wavelet Transform, Differential Absolute Contrast, and Principal Component Thermography are of interest. In the present study, the effects of various data processing methods on PoD curves are compared. DA - 2012/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9ea63f8e-b594-46fa-b67f-fb24aaacc0cc ER - TY - JOUR TI - The crack growth behavior of Incoloy 800H under fatigue and dwell-fatigue conditions at elevated temperature DO - 10.1007/s12206-012-0507-3 AU - Kim, D. J. AU - Seo, D. Y. AU - Tsang, J. AU - Yang, W. J. AU - Lee, J. H. AU - Saari, H. AU - Seok, C. S. T2 - Journal of Mechanical Science and Technology SN - 1738-494X SN - 1976-3824 VL - 26 IS - 7 SP - 2023 EP - 2027 KW - fatigue; dwell-fatigue; crack growth rate; trans-granular; oxidation AB - Fatigue crack growth rate (FCGR) tests with different load ratios and dwell-fatigue crack growth rate (DFCGR) tests with different dwell times were conducted at 750°C for Incoloy 800H. As the load ratio increases from 0.1 to 0.5, the crack growth rate increased and the transition ΔK value from region I to region II (Paris regime) shifted leftward. In DFCGR tests with dwell time of 10 and 30 seconds, the Paris regime started at relatively lower ΔK level and the crack grew much faster than in FCGR tests. However, the crack growth rates between the 10 sec and 30 sec dwell times were relatively similar. The higher crack growth rates in the DFCGR tests compared to FCGR tests was associated with the reduction of the M23C6 precipitates in the vicinity of the advancing crack by the Cr depletion, suggesting the crack propagation in DFCGR conditions was environmentally assisted. The crack growth rate was controlled by trans-granular mode regardless of the dwell time because the dwell time was not enough to cause creep damage. DA - 2012/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 35c5a74d-fce9-4225-828f-cdad142d907a ER - TY - JOUR TI - The effect of microstructure on creep behavior of a powder metallurgy (PM) beta gamma alloy DO - 10.1007/s12206-012-0504-6 AU - Seo, D. Y. AU - Sawatzky, T. AU - Saari, H. AU - Kim, D. J. AU - Au, P. AU - Seok, C. S. T2 - Journal of Mechanical Science and Technology SN - 1738-494X SN - 1976-3824 VL - 26 IS - 7 SP - 2009 EP - 2013 KW - beta gamma TiAl alloy; beta phase; creep; powder metallurgy AB - Pre-alloyed beta gamma titanium aluminide powder with a nominal composition of TiAl-2Nb-2Mo (G2) is consolidated by hot isostatic pressing. After consolidation, a step cooled heat treatment is performed to homogenize the material and produce a fully lamellar microstructure. Various aging heat treatments are then performed to form interfacial beta phase precipitates along lamellar interfaces. The step cooled heat treatment produces a relatively fine microstructure with an average lamellar grain size of 40 μm. The aging heat treatments generate beta phase precipitates along lamellar grain boundaries as well as along lamellar interfaces, and result in limited lamellar degradation and grain growth. However, coarse intergranular grains consisting of beta and gamma grains form during aging. Constant load tensile creep tests are performed on step cooled heat treated and aged specimens. Primary creep resistance, generally, improves with aging time, even with interfacial precipitation, and the limited lamellar degradation occurs with aging. However, total creep life of aged samples decreases with aging time. The microstructures of the tested specimens are characterized and related to the creep behaviour of the TiAl-2Nb-2Mo alloy in the un-aged and aged conditions. DA - 2012/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fe1b5979-9140-4623-bca3-69e6ac73a58e ER - TY - JOUR TI - Transformative research : definitions, approaches and consequences DO - 10.1007/s12064-012-0154-3 AU - Trevors, J. T. AU - Pollack, Gerald H. AU - Saier, Milton H. AU - Masson, Luke T2 - Theory in Biosciences SN - 1431-7613 SN - 1611-7530 VL - 131 IS - 2 SP - 117 EP - 123 KW - biosciences; transformative research; future science; humanistic knowledge; intuitive thought; implementation; scholarship; scientifc method; profound discoveries AB - In this perspective a definition of transformative research (TR) is proposed and discussed. We define TR as that which “transforms” or causes a major change in thought patterns concerning an area of scientific endeavor. This type of research is often elusive, requires different approaches and sometimes depends on a bit of luck. TR concerns intangibles such as human intuition, serendipity, unpredictable events, implausible hypotheses, a well-prepared mind and often interpersonal communications. Examples are provided to illustrate how TR may unfold. Contributions it makes to basic and applied humanistic knowledge are highlighted. DA - 2012/05/25 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4233257a-8027-4791-acc6-02c6039485fe ER - TY - JOUR TI - Cell culture tracking by multivariate analysis of raw LCMS data DO - 10.1007/s12010-012-9661-4 AU - Michaud, François-Thomas AU - Havugimana, Pierre Claver AU - Duchesne, Carl AU - Sanschagrin, François AU - Bernier, Alice AU - Lévesque, Roger C. AU - Garnier, Alain T2 - Applied Biochemistry and Biotechnology SN - 0273-2289 SN - 1559-0291 VL - 167 IS - 3 SP - 474 EP - 488 KW - LCMS; multivariate analysis; protein production; virus production; cell culture monitoring AB - Liquid chromatography mass spectrometry (LCMS) is a powerful technique that could serve to rapidly characterize cell culture protein expression profile and be used as a process monitoring and control tool. However, this application is often hampered by both the sample proteome and the LCMS signal complexities as well as the variability of this signal. To alleviate this problem, culture samples are usually extensively fractionated and pretreated before being analyzed by top-end instruments. Such an approach precludes LCMS usage for routine on-line or at-line application. In this work, by applying multivariate analysis (MA) directly on raw LCMS signals, we were able to extract relevant information from cell culture samples that were simply lyzed. By using the recombinant adenovirus production process as a model, we were able to follow the accumulation of the three major proteins produced, identified their accumulation dynamics, and draw useful conclusions from these results. The combination of LCMS and MA provides a simple, rapid, and precise means to monitor cell culture. DA - 2012/05/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f5f5adb6-01c2-4d1b-9b2f-6bdea12fa999 ER - TY - JOUR TI - Assessment of titanium aluminide alloys for high-temperature nuclear structural applications DO - 10.1007/s11837-012-0471-5 AU - Zhu, Hanliang AU - Wei, Tao AU - Carr, David AU - Harrison, Robert AU - Edwards, Lyndon AU - Hoffelner, Wolfgang AU - Seo, Dongyi AU - Maruyama, Kouichi T2 - JOM SN - 1047-4838 SN - 1543-1851 VL - 64 IS - 12 SP - 1418 EP - 1424 AB - Titanium aluminide (TiAl) alloys exhibit high specific strength, low density, good oxidation, corrosion, and creep resistance at elevated temperatures, making them good candidate materials for aerospace and automotive applications. TiAl alloys also show excellent radiation resistance and low neutron activation, and they can be developed to have various microstructures, allowing different combinations of properties for various extreme environments. Hence, TiAl alloys may be used in advanced nuclear systems as high-temperature structural materials. Moreover, TiAl alloys are good materials to be used for fundamental studies on microstructural effects on irradiation behavior of advanced nuclear structural materials. This article reviews the microstructure, creep, radiation, and oxidation properties of TiAl alloys in comparison with other nuclear structural materials to assess the potential of TiAl alloys as candidate structural materials for future nuclear applications. DA - 2012/10/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5fc8dc17-19aa-45ea-9c5c-dc12ade1b43a ER - TY - JOUR TI - Laser cladding of CPM tool steels on hardened H13 hot-work steel for low-cost high-performance automotive tooling DO - 10.1007/s11837-012-0332-2 AU - Chen, J. AU - Xue, L. T2 - JOM SN - 1047-4838 SN - 1543-1851 VL - 64 IS - 6 SP - 688 EP - 693 AB - This paper summarizes our research on laser cladding of high-vanadium CPM® tool steels (3V, 9V, and 15V) onto the surfaces of low-cost hardened H13 hot-work tool steel to substantially enhance resistance against abrasive wear. The results provide great potential for fabricating high-performance automotive tooling (including molds and dies) at affordable cost. The microstructure and hardness development of the laser-clad tool steels so obtained are presented as well. DA - 2012/06/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 23c4eb65-4cfc-43ff-9124-6cb3fa2b9833 ER - TY - JOUR TI - Biosynthesis of long chain polyunsaturated fatty acids in the marine Ichthyosporean Sphaeroforma arctica DO - 10.1007/s11745-012-3738-2 AU - Vrinten, Patricia AU - Mavraganis, Ioannis AU - Qiu, Xiao AU - Senger, Toralf T2 - Lipids SN - 0024-4201 SN - 1558-9307 VL - 48 IS - 3 SP - 263 EP - 274 KW - Sphaeroforma arctica; Desaturase; Elongase; Very long chain polyunsaturated fatty acids AB - Sphaeroforma arctica is a unique, recently discovered marine protist belonging to a group falling close to the yeast/animal border. S. arctica is found in cold environments, and accordingly has a fatty acid composition containing a high proportion of very long chain polyunsaturated fatty acids, including the ω3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA). Two elongases and five desaturases, representing the complete set of enzymes necessary for the synthesis of DHA from oleic acid, were isolated from this species and characterized in yeast. One elongase showed high conversion rates on a wide range of 18 and 20 carbon substrates, and was capable of sequential elongation reactions. The second elongase had a strong preference for the 20-carbon fatty acids EPA and arachidonic acid, with over 80 % of EPA converted to docosapentaenoic acid (DPA) in the heterologous yeast host. The isolation of a Δ8-desaturase, along with the detection of eicosadienoic acid in S. arctica cultures indicated that this species uses the alternate Δ8-pathway for the synthesis of long-chain polyunsaturated fatty acids. S. arctica also carried a Δ4-desaturase that proved to be very active in the production of DHA from DPA. Finally, a long chain acyl-CoA synthetase from S. arctica improved DHA uptake in the heterologous yeast host and led to an improvement in desaturation and elongation efficiencies. DA - 2012/12/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a2e1b283-a155-446a-83ad-21e96748344e ER - TY - JOUR TI - Failure analysis of cast iron trunk main in Cleveland, Ohio DO - 10.1007/s11668-012-9567-z AU - Rajani, Balvant AU - Lewandowski, John AU - Margevicius, Alex T2 - Journal of Failure Analysis and Prevention SN - 1547-7029 SN - 1864-1245 VL - 12 IS - 3 SP - 217 EP - 236 KW - Cast iron mains; Failure analysis; Failure mechanism; Bell–spigot joint AB - This article describes the failure analyses of a 30”-diameter cast iron main that failed suddenly at the bell–spigot joint in Cleveland, Ohio in March 2008. The main had been operating largely without problems since its installation in 1880. The failure was analyzed using three models developed previously, each of which considered a specific failure mechanism candidate, namely (a) operational load or static analysis, (b) joint failure due to ground movement (settlement), and (c) fatigue failure. Operational load analysis clearly showed that while the factor of safety was significantly reduced in the presence of a concrete vault installed in 2002 just above the pipe, the margin of safety was still sufficient for the main to have performed safely. Ground movement analysis of the jointed pipe showed that the construction of the concrete vault above the joint of the 30”-cast iron main subjected the joint to rotation, which might have ultimately cracked the bell leading to failure. Under this circumstance, two failure scenarios are possible: namely, (a) additional rotation was large enough to cause the bell to split, or (b) additional rotation was sufficient to induce a minor crack in the bell but fatigue (repeated) loading caused the crack to grow over time until the combination of crack length and loading was sufficient to cause the bell to eventually split. The color differences along the fracture surfaces indicated that the fracture occurred in two distinct stages. This observation suggests that the second scenario is more plausible than the first. DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 75c66673-5d2e-45b3-a8c2-840ad4780749 ER - TY - JOUR TI - Influence of thermal cycle frequency on the TGO growth and cracking behaviors of an APS-TBC DO - 10.1007/s11666-012-9824-4 AU - Chen, W. R. AU - Wu, X. AU - Dudzinski, D. T2 - Journal of Thermal Spray Technology SN - 1059-9630 SN - 1544-1016 VL - 21 IS - 6 SP - 1294 EP - 1299 KW - cracking, holding time, TBC, TGO growth, thermal cycling AB - The durability of thermal barrier coatings (TBCs) is controlled by fracture near the interface between the ceramic topcoat and the metallic bond coat, where a layer of thermally grown oxide (TGO) forms during service exposure. In the present work, the influence of thermal cycle frequency on the oxidation performance, in terms of TGO growth and cracking behavior, of an air-plasma-sprayed (APS) Co-32Ni-21Cr-8Al-0.5Y (wt.%) bond coat was studied. The results show that while TGO growth exhibited an initial parabolic growth behavior followed by an accelerated growth stage, higher cycle frequency resulted in a faster TGO growth and a higher crack propagation rate. It is found that a power-law relationship exists between the maximum crack length and the TGO thickness, which is independent of the cycle frequency. This relationship may warrant a TBC life prediction methodology based on the maximum crack length criterion. DA - 2012/12/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 440d428b-f687-4bbd-b592-e5c98a50b1f6 ER - TY - JOUR TI - Effect of pulsed laser ablation and continuous laser heating on the adhesion and cohesion of cold sprayed Ti-6Al-4V coatings DO - 10.1007/s11666-012-9812-8 AU - Perton, M. AU - Costil, S. AU - Wong, W. AU - Poirier, D. AU - Irissou, E. AU - Legoux, J.-G. AU - Blouin, A. AU - Yue, S. T2 - Journal of Thermal Spray Technology SN - 1059-9630 SN - 1544-1016 VL - 21 IS - 6 SP - 1322 EP - 1333 KW - adhesion strength; cold spray; continuous laser pre-heating; gas dynamic spray; kinetic spray; LASAT; pulsed laser ablation; surface preparation; Ti-6Al-4V AB - The individual and cumulative effects of in situ pulsed laser ablation and continuous laser pre-heating on adhesion and cohesion strength of cold sprayed Ti-6Al-4V coatings are investigated. Laser beams were coupled to a cold spray gun in order to ablate and pre-heat the substrate surface a few milliseconds prior to the impact of the spray particles. Cohesion and adhesion strength were evaluated by scratch test, standard ASTM C633 pull test and laser shock (LASAT) technique. The effects of laser ablation before and during cold spray operations were investigated. Results demonstrate that laser ablation of the substrate before cold spraying led to a smooth surface which improved adhesion strength. However, when laser ablation was maintained throughout the cold spray process, i.e., in between the coating layers, a reduction of cohesion and adhesion was observed. These negative effects were circumvented when laser ablation and laser pre-heating were combined. DA - 2012/08/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ecb01057-0bb8-466b-9df1-41e01aa6342b ER - TY - JOUR TI - Optimization of plasma spray process using statistical methods DO - 10.1007/s11666-011-9700-7 AU - Gao, F. AU - Huang, X. AU - Liu, R. AU - Yang, Q. T2 - Journal of Thermal Spray Technology SN - 1059-9630 SN - 1544-1016 VL - 21 IS - 1 SP - 176 EP - 186 KW - axial injection; crack; NiCrAlY coating; oxide; plasma spray; porosity; process optimization; regression equation; Taguchi method; unmelted particle AB - The microstructure features of coatings produced by a plasma spray process are affected significantly by the process parameters such as powder size, spray gun nozzle size, total plasma gas flow, ratio of H2 + N2 over total gas flow, and so on. This article presents a study of the effects of these parameters on the microstructure (porosity, formation of crack, unmelted particle and oxide phase) of NiCrAlY coatings deposited by the Mettech Axial III™ System. A Taguchi array is used to design the spraying process parameters. The results of the microstructure evaluation are used to generate regression equations for the prediction of coating microstructure based on process parameters. The results predicted from the regression equations are in good agreement with the experimental results according to a confidence level of 0.95. Among the parameters examined, the powder size and the ratio of H2 + N2 over total gas flow rate are the most significant parameters affecting the occurrence of crack, porosity, unmelted particle and oxide. Within the range of the designed process parameters, lower powder size and higher ratio of H2 + N2 over total gas flow rate lead to less cracks, pores, unmelted particles but more oxides. Nozzle size has marginal influence on oxides which increase with nozzle size. Gas flow rate has no direct influence on any coating feature evaluated with the range of variation. DA - 2012/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 34a8b390-6f81-44f1-9ea1-4764b4b8091c ER - TY - JOUR TI - Development of the process index for NiCrAlY coatings with the Mettech Axial III™ System DO - 10.1007/s11665-012-0326-9 AU - Gao, Feng AU - Yang, Qi AU - Huang, Xiao AU - Liu, Rong T2 - Journal of Materials Engineering and Performance SN - 1059-9495 SN - 1544-1024 VL - 22 IS - 3 SP - 713 EP - 722 KW - cracks; Mettech Axial III; oxides; pores; process index; regression equations; spray parameters; Taguchi arrays; unmelted particles AB - NiCrAlY coatings were deposited using the Mettech Axial III™ plasma spray system. The microstructural features of the coatings, such as the porosity, crack, un-melted particle, and oxide content, were analyzed to investigate the effects of the spray process parameters on these features. Two Taguchi arrays were used to examine the effects of the spray process parameters such as powder size, ratio of (H2 + N2) gas flow over total gas flow, current, spray-gun nozzle size, and spray distance, on the microstructural features of the coatings. The results from statistical analysis are used to create regression equations to predict the microstructural features of the coatings. In the regression equations, a process index (PI) is used as a complex variable incorporating a number of process parameters. The results from an additional set of experiments are used to verify the validity of the regression equations. It has been demonstrated that the equations correlate well with the results from the subsequent set of experiments. It is concluded from this study that the PI can be used to categorize coating qualities with respect to the extent of crack, porosity, unmelted particle, and oxide content in the coating. These equations can also serve as an initial step in developing process parameters by means of the Mettech Axial III™ System. DA - 2012/07/28 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : db51c764-cffa-4066-ab76-0dce0c0856bc ER - TY - JOUR TI - A true-stress creep model based on deformation mechanisms for polycrystalline materials DO - 10.1007/s11665-012-0191-6 AU - Wu, Xijia AU - Williams, Steve AU - Gong, Diguang T2 - Journal of Materials Engineering and Performance SN - 1059-9495 SN - 1544-1024 VL - 21 IS - 11 SP - 2255 EP - 2262 KW - creep; creep life prediction; deformation mechanism AB - A true-stress creep model has been developed based on well-recognized deformation mechanisms, i.e., dislocation glide, dislocation climb, and grain boundary sliding. The model provides a physics-based description of the entire creep deformation process with regards to the strain-time history (primary, secondary, and tertiary creep), rupture strain and lifetime, which finds good agreement with experimental observations for Waspaloy. A deformation-mechanism map is constructed for Waspaloy, and a creep failure criterion is defined by the dominant deformation mechanisms leading to intergranular/transgranular fracture. Thus, the model is a self-consistent tool for creep life prediction. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5366c419-2c6c-4611-b6b3-df72b2c10663 ER - TY - JOUR TI - Effect of Mn, Si, and cooling rate on the formation of iron-rich intermetallics in 206 Al-Cu cast alloys DO - 10.1007/s11663-012-9694-7 AU - Liu, K. AU - Cao, X. AU - Chen, X.-G. T2 - Metallurgical and Materials Transactions B SN - 1073-5615 SN - 1543-1916 VL - 43 IS - 5 SP - 1231 EP - 1240 AB - The solidification structures of commercial 206 Al-Cu cast alloys with 0.15 pct Fe have been studied using thermal analysis (TA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and electron backscattered diffraction (EBSD). The EBSD results have shown that there are two iron-rich intermetallics: Chinese script α-Fe and platelet-like β-Fe. The addition of either Mn or Si has helped to promote the formation of α-Fe and hinder the precipitate of β-Fe. The combined addition of both Mn and Si is even more effective than the individual addition of either Mn or Si. The full solidification sequence of the 206 cast alloy has been established. The volume percent and formation temperature increase for α-Fe but decrease for β-Fe with increasing cooling rate. The platelet β-Fe can be effectively suppressed in 206 cast alloys by controlling the alloy chemistry and cooling rate. A casting process map is proposed to correlate the Mn and Si contents with cooling rates for the 206 cast alloys. DA - 2012/06/29 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f2c553a2-5fa5-4872-b14e-11a9611a351f ER - TY - JOUR TI - Effect of postweld heat treatment on microstructure, hardness, and tensile properties of laser-welded Ti-6Al-4V DO - 10.1007/s11661-012-1230-5 AU - Kabir, Abu Syed H. AU - Cao, Xinjin AU - Gholipour, Javad AU - Wanjara, Priti AU - Cuddy, Jonathan AU - Birur, Anand AU - Medraj, Mamoun T2 - Metallurgical and Materials Transactions A SN - 1073-5623 SN - 1543-1940 VL - 43 IS - 11 SP - 4171 EP - 4184 AB - The effects of postweld heat treatment (PWHT) on 3.2-mm- and 5.1-mm-thick Ti-6Al-4V butt joints welded using a continuous wave (CW) 4-kW Nd:YAG laser welding machine were investigated in terms of microstructural transformations, welding defects, and hardness, as well as global and local tensile properties. Two postweld heat treatments, i.e., stress-relief annealing (SRA) and solution heat treatment followed by aging (STA), were performed and the weld qualities were compared with the as-welded condition. A digital image correlation technique was used to determine the global tensile behavior for the transverse welding samples. The local tensile properties including yield strength and maximum strain were determined, for the first time, for the laser-welded Ti-6Al-4V. The mechanical properties, including hardness and the global and local tensile properties, were correlated to the microstructure and defects in the as-welded, SRA, and STA conditions. DA - 2012/06/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ce2d4866-c3c7-4b91-8df0-96b2b9022e10 ER - TY - JOUR TI - A new iron-rich intermetallic-Al m Fe phase in Al-4.6Cu-0.5Fe cast alloy DO - 10.1007/s11661-011-1004-5 AU - Liu, K. AU - Cao, X. AU - Chen, X.-G. T2 - Metallurgical and Materials Transactions A SN - 1073-5623 SN - 1543-1940 VL - 43 IS - 4 SP - 1097 EP - 1101 AB - A new iron-rich intermetallic, Al m Fe, is observed, for the first time, in the important A206 (Al-4.6Cu-0.5Fe) cast alloy and identified using electron backscattered diffraction (EBSD) and a transmission electron microscope (TEM). Results show that Chinese script Al m Fe can precipitate as the dominant iron-rich intermetallic at high iron content (0.5 wt pct) and low cooling rate (0.2 K/s). EBSD and TEM results confirmed that Al m Fe has body-centered-tetragonal structure with an average m of approximately 4.2. DA - 2012/01/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 26e3bde7-bbd1-476f-a50a-ecd93a8e2ac0 ER - TY - JOUR TI - Electronic and optical properties of semiconductor and graphene quantum dots DO - 10.1007/s11467-011-0200-5 AU - Sheng, Wei-dong AU - Korkusinski, Marek AU - Güçlü, Alev Devrim AU - Zielinski, Michal AU - Potasz, Pawel AU - Kadantsev, Eugene S. AU - Voznyy, Oleksandr AU - Hawrylak, Pawel T2 - Frontiers of Physics SN - 2095-0462 SN - 2095-0470 VL - 7 IS - 3 SP - 328 EP - 352 KW - quantum dots; electronic structure; multiexciton; graphene; magnetis AB - Our recent work on the electronic and optical properties of semiconductor and graphene quantum dots is reviewed. For strained self-assembled InAs quantum dots on GaAs or InP substrate atomic positions and strain distribution are described using valence-force field approach and continuous elasticity theory. The strain is coupled with the effective mass, k · p, effective bond-orbital and atomistic tight-binding models for the description of the conduction and valence band states. The single-particle states are used as input to the calculation of optical properties, with electron-electron interactions included via configuration interaction (CI) method. This methodology is used to describe multiexciton complexes in quantum dot lasers, and in particular the hidden symmetry as the underlying principle of multiexciton energy levels, manipulating emission from biexcitons for entangled photon pairs, and optical control and detection of electron spins using gates. The self-assembled quantum dots are compared with graphene quantum dots, one carbon atom-thick nanostructures. It is shown that the control of size, shape and character of the edge of graphene dots allows to manipulate simultaneously the electronic, optical, and magnetic properties in a single material system. DA - 2012/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1fa60f94-ffb0-4266-b5d7-27013730e65b ER - TY - JOUR TI - Conversion of lignin to aromatic-based chemicals (L-chems) and biofuels (L-fuels) DO - 10.1016/j.biortech.2012.06.061 AU - Beauchet, R. AU - Monteil-Rivera, F. AU - Lavoie, J. M. T2 - Bioresource Technology SN - 09608524 VL - 121 SP - 328 EP - 334 KW - Lignin KW - depolymerisation KW - monomers KW - oligomers KW - biofuel AB - Conversion of lignin into chemicals and biofuels was performed using the commercial Kraft lignin, Indulin AT. Lignin was depolymerised in an aqueous alkaline solution using a continuous flow reactor generating four fractions. First is the gas fraction (mainly CO₂), the second includes methanol, acetic acid and formic acid, thus defined as small organic compounds and third one (up to 19.1 wt.% of lignin) is mostly composed of aromatic monomers. The fourth fraction (45–70 wt.%) contains oligomers (polyaromatic molecules) and modified lignin. Pyrocatechol was the most abundant product at high severities (315°C) with selectivity up to 25.8%. ³¹P NMR showed the loss of almost all aliphatic OH groups and apparition of catechol groups during depolymerisation. DA - 2012/06/29 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 13b9c928-8271-4816-a0d9-3dab2640c6ac ER - TY - JOUR TI - Glutathione, glutathione S-transferase, and glutathione conjugates, complementary markers of oxidative stress in aquatic biota DO - 10.1007/s11356-012-0909-x AU - Hellou, Jocelyne AU - Ross, Neil W. AU - Moon, Thomas W. T2 - Environmental Science and Pollution Research SN - 0944-1344 SN - 1614-7499 VL - 19 IS - 6 SP - 2007 EP - 2023 KW - antioxidants; oxidative stress; conjugates; metabolites; glutathione; review; analyses; integration of biomarkers AB - Contaminants are ubiquitous in the environment and their impacts are of increasing concern due to human population expansion and the generation of deleterious effects in aquatic species. Oxidative stress can result from the presence of persistent organic pollutants, metals, pesticides, toxins, pharmaceuticals, and nanomaterials, as well as changes in temperature or oxygen in water, the examined species, with differences in age, sex, or reproductive cycle of an individual. The antioxidant role of glutathione (GSH), accompanied by the formation of its disulfide dimer, GSSG, and metabolites in response to chemical stress, are highlighted in this review along with, to some extent, that of glutathione S-transferase (GST). The available literature concerning the use and analysis of these markers will be discussed, focusing on studies of aquatic organisms. The inclusion of GST within the suite of biomarkers used to assess the effects of xenobiotics is recommended to complement that of lipid peroxidation and mixed function oxygenation. Combining the analysis of GSH, GSSG, and conjugates would be beneficial in pinpointing the role of contaminants within the plethora of causes that could lead to the toxic effects of reactive oxygen species. DA - 2012/04/25 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5ee788d7-aec9-47fb-b22f-6fe1cd9ed8ea ER - TY - JOUR TI - Probing inhibitory effects of nanocrystalline cellulose: inhibition versus surface charge DO - 10.1039/c2nr11886f AU - Male, Keith B. AU - Leung, C. W. AU - Montes, Johnny AU - Kamen, Amine AU - Luong, John H. T. T2 - Nanoscale SN - 2040-3364 SN - 2040-3372 VL - 4 IS - 4 SP - 1373 EP - 1379 AB - NCC derived from different biomass sources was probed for its plausible cytotoxicity by electric cell-substrate impedance sensing (ECIS). Two different cell lines, Spodoptera frugiperda Sƒ9 insect cells and Chinese hamster lung fibroblast V79, were exposed to NCC and their spreading and viability were monitored and quantified by ECIS. Based on the 50%-inhibition concentration (ECIS₅₀), none of the NCC produced was judged to have any significant cytotoxicity on these two cell lines. However, NCC derived from flax exhibited the most pronounced inhibition on Sƒ9 compared to hemp and celluslose powder. NCCs from flax and hemp pre-treated with pectate lyase were also less inhibitory than NCCs prepared from untreated flax and hemp. Results also suggested a correlation between the inhibitory effect and the carboxylic acid contents on the NCC. DA - 2012/01/04 PY - 2012 PB - RSC Publishing LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2b7c087c-cb59-42f3-98c0-99a169cf5887 ER - TY - JOUR TI - Green strategy guided by Raman spectroscopy for the synthesis of ammonium carboxylated nanocrystalline cellulose and the recovery of byproducts DO - 10.1021/sc3001367 AU - Lam, Edmond AU - Leung, Alfred C. W. AU - Liu, Yali AU - Majid, Ehsan AU - Hrapovic, Sabahudin AU - Male, Keith B. AU - Luong, John H. T. T2 - ACS Sustainable Chemistry & Engineering SN - 2168-0485 VL - 1 IS - 2 SP - 278 EP - 283 KW - Nanocrystalline cellulose KW - Raman spectroscopy KW - persulfate KW - sulfate KW - sulfuric acid AB - A one-pot green procedure for the treatment of cellulosic biomass with ammonium persulfate (APS) was developed for the synthesis of highly crystalline carboxylated nanocrystalline cellulose (NCC–COOH), an emerging nanomaterial with a plethora of diversified applications. Raman spectroscopy proved applicable for monitoring the fate of APS and its two byproducts during the production of NCC–COOH from microcrystalline cellulose (MCC). The two main byproducts were then identified and quantified as ammonium sulfate (AS) and H₂SO₄ with the latter accounted for 60% of the total sulfate ions in solution. On the basis of such findings, one-step neutralization of H₂SO₄ and NCC with NH₄OH immediately after reaction was implemented for the formation of additional AS, followed by its quantitative recovery by precipitation. This was a very effective and critical step in waste stream management and cost reduction for the large scale production of NCC. In addition, the process resulted in highly crystalline NCC with COO⁻NH₄⁺ groups, a nanomaterial with improved dispersion and thermal characteristics over NCC with COOH and COO⁻Na⁺ groups. DA - 2012/12/17 PY - 2012 PB - ACS Publications LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 80becf3c-b467-4b58-81e8-6753d02ee465 ER - TY - JOUR TI - Integration of deep transcript and targeted metabolite profiles for eight cultivars of opium poppy DO - 10.1007/s11103-012-9913-2 AU - Desgagné-Penix, Isabel AU - Farrow, Scott C. AU - Cram, Dustin AU - Nowak, Jacek AU - Facchini, Peter J. T2 - Plant Molecular Biology SN - 0167-4412 SN - 1573-5028 VL - 79 IS - 3 SP - 295 EP - 313 KW - 454 Pyrosequencing; Benzylisoquinoline alkaloid; Opium poppy; Metabolite profiling; Transcriptomic AB - Recent advances in DNA sequencing technology and analytical mass spectrometry are providing unprecedented opportunities to develop the functional genomics resources required to investigate complex biological processes in non-model plants. Opium poppy produces a wide variety of benzylisoquinoline alkaloids (BIAs), including the pharmaceutical compounds codeine, morphine, noscapine and papaverine. A functional genomics platform to identify novel BIA biosynthetic and regulatory genes in opium poppy has been established based on the differential metabolite profile of eight selected cultivars. Stem cDNA libraries from each of the eight opium poppy cultivars were subjected to 454 pyrosequencing and searchable expressed sequence tag databases were created from the assembled reads. These deep and integrated metabolite and transcript databases provide a nearly complete representation of the genetic and metabolic variances responsible for the differential occurrence of specific BIAs in each cultivar as demonstrated using the biochemically well characterized pathway from tyrosine to morphine. Similar correlations between the occurrence of specific transcripts and alkaloids effectively reveals candidate genes encoding uncharacterized biosynthetic enzymes as shown using cytochromes P450 potentially involved in the formation of papaverine and noscapine. DA - 2012/04/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : edc89b53-e870-4d45-93a7-7a039eda284c ER - TY - JOUR TI - A molecular and proteomic investigation of proteins rapidly released from triticale pollen upon hydration DO - 10.1007/s11103-012-9897-y AU - Zaidi, Mohsin A. AU - O’Leary, Stephen AU - Wu, Shaobo AU - Gleddie, Steve AU - Eudes, François AU - Laroche, André AU - Robert, Laurian S. T2 - Plant Molecular Biology SN - 0167-4412 SN - 1573-5028 VL - 79 IS - 1-2 SP - 101 EP - 121 KW - Triticale; pollen; tapetum; allergens; proteome; pollen hydration AB - Analysis of Triticale (×Triticosecale Wittmack cv. AC Alta) mature pollen proteins quickly released upon hydration was performed using two-dimensional gel electrophoresis followed by mass spectrometry. A total of 17 distinct protein families were identified and these included expansins, profilins, and various enzymes, many of which are pollen allergens. The corresponding genes were obtained and expression studies revealed that the majority of these genes were only expressed in developing anthers and pollen. Some genes including glucanase, glutathione peroxidase, glutaredoxin, and a profilin were found to be widely expressed in different reproductive and vegetative tissues. Group 11 pollen allergens, polygalacturonase, and actin depolymerizing factor were characterized for the first time in the Triticeae. This study represents a distinctive combination of proteomic and molecular analyses of the major cereal pollen proteins released upon hydration and therefore at the forefront of pollen-stigma interactions. DA - 2012/02/26 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ac0ddc3d-5967-428b-974d-443a4666a8ae ER - TY - JOUR TI - Noninvasive cell-based impedance spectroscopy for real-time probing inhibitory effects of Graphene derivatives DO - 10.1021/am301060z AU - Male, Keith B. AU - Lam, Edmond AU - Montes, Johnny AU - Luong, John H. T. T2 - ACS Applied Materials & Interfaces SN - 1944-8244 SN - 1944-8252 VL - 4 IS - 7 SP - 3643 EP - 3649 KW - Graphene KW - cytotoxicity KW - electric cell-substrate impedance sensing KW - insect cells KW - viability assay AB - Three water-dispersible graphene derivatives, graphene oxide (GO), sulfonated graphene oxide (SGO), and sulfonated graphene (SG), were prepared and probed for their plausible cytotoxicity by non-invasive electric cell-substrate impedance sensing (ECIS). With Spodoptera frugiperda Sƒ9 insect cells adhered on gold microelectrodes as an active interface, it is feasible to monitor changes in impedance upon exposure to different graphene derivatives. Sƒ9 insect cells were then exposed to different concentrations of graphene derivatives and their spreading and viability were monitored and quantified by ECIS in real-time. On the basis of the 50% inhibition concentration (ECIS₅₀), none of the graphene derivatives were judged to have any significant cytotoxicity with respect to the chosen cell line as the ECIS₅₀ values were all above 100 μg/mL. However, all graphene derivatives exhibited inhibitory effects on the Sƒ9 response at the cell spreading level with the following order: SG (ECIS₅₀ = 121 ± 8 μg/mL), SGO (ECIS₅₀ = 151 ± 9 μg/mL), and GO (ECIS₅₀ = 232 ± 27 μg/mL), reflecting differences observed in their ζ-potential and surface area. The presence of phenyl sulfonyl groups in SGO and SG improves their aqueous dispersity which enables these materials to have a greater inhibitory effect on Sƒ9 insect cells in comparison to GO. Such results were corroborated well with the cell count and viability by the Trypan Blue exclusion assay. DA - 2012/07/02 PY - 2012 PB - ACS Publications LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 59037bb0-5509-4973-8c49-dc80e43de5b7 ER - TY - JOUR TI - Quantification of superparamagnetic iron oxide with large dynamic range using TurboSPI DO - 10.1016/j.jmr.2012.01.017 AU - Rioux, James A. AU - Brewer, Kimberly D. AU - Beyea, Steven D. AU - Bowen, Chris V. T2 - Journal of Magnetic Resonance SN - 1090-7807 VL - 216 SP - 152 EP - 160 KW - Quantification KW - relaxometry KW - single point imaging KW - iron oxide KW - static dephasing AB - This work proposes the use of TurboSPI, a multi-echo single point imaging sequence, for the quantification of labeled cells containing moderate to high concentrations of iron oxide contrast agent. At each kspace location, TurboSPI acquires several hundred time points during a spin echo, permitting reliable relaxation rate mapping of large-R*₂ materials. An automatic calibration routine optimizes image quality by promoting coherent alignment of spin and stimulated echoes throughout the multi-echo train, and this calibration is sufficiently robust for in vivo applications. In vitro relaxation rate measurements of SPIO-loaded cervical cancer cells exhibit behavior consistent with theoretical predictions of the static dephasing regime in the spin echo case; the relaxivity measured with TurboSPI was 10.47 ± 2.3 s⁻¹/mG, comparable to the theoretical value of 10.78 s⁻¹/mG. Similar measurements of micron-sized iron oxide particles (0.96 µm and 1.63 µm diameter) show a reduced relaxivity of 8.06 ± 0.68 s⁻¹/mG and 7.13 ± 0.31 s⁻¹/mG respectively, indicating that the static dephasing criterion was not met. Nonetheless, accurate quantification of such particles is demonstrated up to R*₂ = 900 s⁻¹, with a potentially higher upper limit for loaded cells having a more favorable R'₂:R₂ ratio. Based on the cells used in this study, reliable quantification of cells loaded with 10 pg of iron per cell should be possible up to a density of 27 million cells/mL. Such quantification will be of crucial importance to the development of longitudinal monitoring for cellular therapy and other procedures using iron-labeled cells DA - 2012/02/04 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 910bc48c-807c-4220-b7a2-e89b678b61a8 ER - TY - JOUR TI - Magnetic resonance microscopy for assessment of morphological changes in hydrating hydroxypropylmethyl cellulose matrix tablets in situ DO - 10.1007/s11095-012-0837-y AU - Kulinowski, Piotr AU - Młynarczyk, Anna AU - Dorożyński, Przemysław AU - Jasiński, Krzysztof AU - Gruwel, Marco L. H. AU - Tomanek, Bogusław AU - Węglarz, Władysław P. T2 - Pharmaceutical Research SN - 0724-8741 SN - 1573-904X VL - 29 IS - 12 SP - 3420 EP - 3433 KW - controlled release; hydroxypropylmethyl cellulose (HPMC); pharmaceutical magnetic resonance imaging (MRI); swellable matrix tablets; T2 magnetic resonance relaxometry AB - Purpose To resolve contradictions found in morphology of hydrating hydroxypropylmethyl cellulose (HPMC) matrix as studied using Magnetic Resonance Imaging (MRI) techniques. Until now, two approaches were used in the literature: either two or three regions that differ in physicochemical properties were identified. Methods Multiparametric, spatially and temporally resolved T2 MR relaxometry in situ was applied to study the hydration progress in HPMC matrix tablets using a 11.7 T MRI system. Two spin-echo based pulse sequences—one of them designed to specifically study short T2 signals—were used. Results Two components in the T2 decay envelope were estimated and spatial distributions of their parameters, i.e. amplitudes and T2 values, were obtained. Based on the data, five different regions and their temporal evolution were identified: dry glassy, hydrated solid like, two interface layers and gel layer. The regions were found to be separated by four evolving fronts identified as penetration, full hydration, total gelification and apparent erosion. Conclusions The MRI results showed morphological details of the hydrating HPMC matrices matching compound theoretical models. The proposed method will allow for adequate evaluation of controlled release polymeric matrix systems loaded with drug substances of different solubility. DA - 2012/08/25 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 532b8c86-79f5-478f-b689-b3700641f26c ER - TY - JOUR TI - Cyclic oxidation and interdiffusion behaviour of a NiCrAlY coated powder metallurgy beta gamma TiAl–2Nb–2Mo alloy DO - 10.1007/s11085-012-9290-x AU - Kim, D. J. AU - Huang, X. AU - Seo, D. Y. AU - Kim, Y.-W. T2 - Oxidation of Metals SN - 0030-770X SN - 1573-4889 VL - 78 IS - 1-2 SP - 31 EP - 50 KW - beta gamma alloy; NiCrAlY coating; powder metallurgy; cyclic oxidation AB - A new beta-gamma TiAl–2Nb–2Mo alloy was synthesized using powder metallurgy process and coated with NiCrAlY by air plasma spray technique. The cyclic oxidation behaviour of the coated beta-gamma alloy was investigated at 1,000 °C for up to 800 cycles. During cyclic oxidation testing, titanium nitride layer was found to form at the interface between NiCrAlY and TiAl–2Nb–2Mo and the thickness of the titanium nitride layer increased with oxidation cycles. Additionally, outward diffusion of Ti from the beta-gamma substrate caused the formation of titanium oxides on the coating surface after 630 cycles. Inward diffusion of Ni from NiCrAlY led to the formation of an inner diffusion zone containing NiAlTi and mixture of NiAlTi + TiAl. Due to the spallation of coating scales on the circumferential surface of the button specimens, weight loss was observed after 120 cycles; however, NiCrAlY coating on both top and bottom surfaces of the specimens remained in contact with the substrate for up to 800 cycles. Due to the inward and outward diffusion of various elements, one third of the NiCrAlY coating was consumed after 800 cycles, which suggests the need for diffusion barrier coating at the interface between the NiCrAlY coating and the TiAl–2Nb–2Mo alloy. DA - 2012/03/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0109c53d-fa26-49c3-adc6-40813d28982c ER - TY - JOUR TI - Picosecond all-optical switching using nonlinear Mach–Zehnder with silicon subwavelength grating and photonic wire arms DO - 10.1007/s11082-012-9609-5 AU - Glesk, I. AU - Bock, P. J. AU - Cheben, P. AU - Schmid, J. H. AU - Lapointe, J. AU - Janz, S. T2 - Optical and Quantum Electronics SN - 0306-8919 SN - 1572-817X VL - 44 IS - 12-13 SP - 613 EP - 621 KW - integrated picosecond all-optical switch; diffraction gratings; subwavelength structures; all-optical switching device AB - We investigate the picosecond switching capabilities of a planar waveguide interferometric photonic device when used for all-optical wavelength conversion of one picosecond pulses. Our device comprises a subwavelength grating waveguide arm and a photonic wire waveguide arm in a Mach–Zehnder configuration, fabricated on the silicon-on-insulator material platform. No detrimental effects of pulse broadening for transient pulses were observed. DA - 2012/08/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1a4bf94d-6047-4c5f-a2f4-c95eec96452c ER - TY - JOUR TI - Development of a Fourier-transform waveguide spectrometer for space applications DO - 10.1007/s11082-012-9596-6 AU - Florjańczyk, Mirosław AU - Alonso-Ramos, Carlos AU - Bock, Przemek AU - Bogdanov, Alexei AU - Cheben, Pavel AU - Molina-Fernández, Íñigo AU - Janz, Siegfried AU - Lamontagne, Boris AU - Ortega-Moñux, Alejandro AU - Scott, Alan AU - Sinclair, Kenneth AU - Solheim, Brian AU - Xu, Dan-Xia T2 - Optical and Quantum Electronics SN - 0306-8919 SN - 1572-817X VL - 44 IS - 12-13 SP - 549 EP - 556 KW - spectrometers and spectroscopic instrumentation; planar waveguides; Fourier transform spectroscopy AB - We describe the development of a waveguide Fourier-transform spectrometer for space-borne high-resolution sensing. A prototype device is designed to monitor the water vapor absorption band near 1,364 nm with a resolution of 0.05 nm. It has no moving parts and is based on a unique concept of arrayed interferometers implemented in silicon-on-insulator planar waveguide chip. The optical input is formed by many independent waveguides, providing a significantly increased light gathering capability (étendue) compared to single-waveguide input configurations. Enhancements of the spectrometer capabilities are achieved by stacking planar waveguide layers and by using surface gratings to couple light into the waveguides. DA - 2012/06/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4d289c6e-da70-4cbd-931d-ecdc3a86ab0d ER - TY - JOUR TI - Grating couplers for thick SOI rib waveguides DO - 10.1007/s11082-012-9569-9 AU - Alonso-Ramos, C. AU - Ortega-Moñux, A. AU - Molina-Fernández, I. AU - Cheben, P. AU - Zavargo-Peche, L. AU - Halir, R. AU - Janz, S. AU - Xu, D.-X. AU - Kim, N. AU - Lamontagne, B. T2 - Optical and Quantum Electronics SN - 0306-8919 SN - 1572-817X VL - 44 IS - 12-13 SP - 535 EP - 540 KW - grating coupler; planar waveguide; rib waveguide; SOI; FT spectrometer AB - The use of grating couplers in high index contrast waveguides like silicon on insulator (SOI) offers several advantages over other coupling approaches, including better alignment tolerances and allowing for wafer-scale testing. The grating couplers were developed for nanometric SOI waveguides (Si-wires), and recently also for micrometric rib waveguides. In this paper we review our work in fiber-to-chip grating couplers for thick SOI rib waveguides, where a coupling efficiency of −2.2 dB was demonstrated experimentally. We also discuss the use of grating couplers to improve optical throughput (étendue) of a planar waveguide Fourier-Transform (FT) spectrometer implemented in thick rib waveguides. DA - 2012/03/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 33b872f4-6fff-49fc-8be1-21d6481b9960 ER - TY - JOUR TI - Single etch grating couplers for mass fabrication with DUV lithography DO - 10.1007/s11082-012-9563-2 AU - Halir, R. AU - Zavargo-Peche, L. AU - Xu, D.-X. AU - Cheben, P. AU - Ma, R. AU - Schmid, J. H. AU - Janz, S. AU - Densmore, A. AU - Ortega-Moñux, A. AU - Molina-Fernández, Í. AU - Fournier, M. AU - Fédeli, J.-M. T2 - Optical and Quantum Electronics SN - 0306-8919 SN - 1572-817X VL - 44 IS - 12-13 SP - 521 EP - 526 KW - fiber-to-chip grating coupler; deep ultraviolet lithography; single etch process AB - Surface grating couplers enable efficient coupling of light between optical fibers and planar waveguide circuits. While traditional grating designs require two etch steps for efficient coupling to silicon-on-insulator waveguides, recently proposed subwavelength structured gratings can achieve the same coupling efficiencies with a single etch step, thereby significantly reducing fabrication complexity. Here we demonstrate that such couplers can be fabricated on a large scale with ultra-violet lithography, achieving a 5 dB coupling efficiency at 1,550 nm. Through both simulations and experiments we give physical insight on how pattern fidelity impacts the performance of these couplers, and propose strategies to deal with inevitable process variations. DA - 2012/02/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3ae6e66a-103d-4df0-8445-37629981b59d ER - TY - JOUR TI - Fast light-emitting silicon-germanium nanostructures for optical interconnects DO - 10.1007/s11082-012-9549-0 AU - Lockwood, D. J. AU - Tsybeskov, L. T2 - Optical and Quantum Electronics SN - 0306-8919 SN - 1572-817X VL - 44 IS - 12-13 SP - 505 EP - 512 KW - silicon; germanium; dots; photoluminescence; electroluminescence AB - Epitaxially-grown Si/SiGe quantum dot complexes produce efficient photoluminescence and electroluminescence in the desired spectral range of 1.3–1.6µm. The latest progress in our understanding of the physics of carrier recombination in Si/SiGe nanostructures is reviewed, and a new route toward CMOS compatible light emitters is proposed. DA - 2012/02/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2af93d5f-1fd9-4d61-916e-893f1e113396 ER - TY - JOUR TI - A model for deployment of a freefall lifeboat from a moving ramp into waves DO - 10.1007/s11044-012-9308-9 AU - Raman-Nair, W. AU - White, M. T2 - Multibody System Dynamics SN - 1384-5640 SN - 1573-272X VL - 29 IS - 3 SP - 327 EP - 342 KW - freefall lifeboat; moving ramp; water entry; Kane`s equation AB - The equations of motion of a freefall lifeboat are formulated using Kane’s method. Deployment from a moving ramp is assumed to occur in a known plane and a 2D model suffices. A segmented approach is used to model ramp contact. A separate 3D model is presented for the water entry phase. The hydrodynamic loads at water entry are also modeled using a segmented approach. The equations are solved numerically using a standard Runge–Kutta MATLAB routine. DA - 2012/03/28 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 259951a5-62d5-4d74-b2bb-7badf29aafd4 ER - TY - JOUR TI - Introgression of Brassica rapa subsp. sylvestris blackleg resistance into B. napus DO - 10.1007/s11032-012-9735-6 AU - Yu, F. AU - Lydiate, D. J. AU - Gugel, R. K. AU - Sharpe, A. G. AU - Rimmer, S. R. T2 - Molecular Breeding SN - 1380-3743 SN - 1572-9788 VL - 30 IS - 3 SP - 1495 EP - 1506 KW - Brassica napus; Brassica rapa; Leptosphaeria maculans; molecular mapping; marker-assisted selectio AB - Blackleg, caused by Leptosphaeria maculans, is one of the most economically important diseases of Brassica napus worldwide. Two blackleg resistance genes, LepR1 and LepR2, from B. rapa subsp. sylvestris (BRS) were previously identified. To transfer LepR1 and LepR2 from BRS into B. napus, interspecific hybridizations were made between the two species to form allotriploids. Analysis of microsatellite markers in two BC1 populations, WT3BC1 and WT4BC1, indicated that segregation fit a 1:1 ratio for BRS and non-BRS alleles on the A-genome linkage groups N2 and N10, the locations of LepR1 and LepR2, respectively. However, recombination frequencies in the allotriploid BC1 populations were at least twice those in the amphidiploid. The number of C-genome chromosomes in the BC1 plants was determined through marker analysis, which indicated averages of 5.9 and 5.0 per plant in the WT3BC1 and WT4BC1 populations, respectively. Two L. maculans isolates, WA51 and pl87-41, were used to differentiate plants carrying resistance genes LepR1 and LepR2. Surprisingly, only 4.0 and 16.6 % of the plants were resistant to isolates WA51 and pl87-41, respectively, in the WT3BC1 population, while 17.9 and 33.3 % of the plants were resistant to these isolates, respectively, in the WT4BC1 population. No association of resistance to isolate WA51 or pl87-41 with linkage group N2 or N10 was found. Based on cotyledon resistance and marker-assisted selection (MAS), BC1 plant WT4-4, which carried a resistance gene similar to LepR1, herein designated LepR1′, and BC2S1 plant WT3-21-25-9, which carried LepR2′, were identified. These plants were successively backcrossed with B. napus and MAS was employed in each generation to reduce non-resistance alleles associated with the BRS genome and to recover the full complement of C-genome chromosomes, resulting in highly blackleg-resistant B. napus lines. DA - 2012/05/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 97221fd0-4a42-4ef3-9032-778bfdcb34ba ER - TY - JOUR TI - The sorption behaviors in PLLA-CO2 system and its effect on foam morphology DO - 10.1007/s10965-012-9827-3 AU - Liao, Xia AU - Nawaby, Arghavan V. T2 - Journal of Polymer Research SN - 1022-9760 SN - 1572-8935 VL - 19 IS - 3 KW - Poly(L-lactic acid) (PLLA); CO2; Retrograde behavior; crystallization; foam morphology AB - The sorption behavior, physical properties, and foam morphologies in poly(L-lactic acid) (PLLA)-CO2 system were studied in this paper. The solubility and diffusion coefficient of CO2 in PLLA in the range of 0 °C to 45 °C and pressure up to 5.5 MPa were investigated. The diffusion coefficients were analyzed to determine the plasticization glass transition temperature (T g ) of the PLLA-CO2 systems. The data of T g s of PLLA at various CO2 pressures demonstrated that PLLA-CO2 system exhibited a retrograde vitrification behavior, which has never been reported on semi-crystalline polymer-gas system by systematic measurement of solubility data. The sorption curves of PLLA at certain temperatures and pressures exhibited a characteristic keen which indicated the rejection of CO2 from the polymer matrix due to CO2-induced crystallization. The fundamental understanding of PLLA-CO2 interactions was utilized to control the CO2 solubility and crystallinity in PLLA thus the physical properties, in order to develop various unique foam structures. DA - 2012/03/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cd9f5238-1bc6-4d40-8d2b-7152a442134d ER - TY - JOUR TI - Resolution-by-proxy : a simple measure for assessing and comparing the overall quality of NMR protein structures DO - 10.1007/s10858-012-9637-2 AU - Berjanskii, Mark AU - Zhou, Jianjun AU - Liang, Yongjie AU - Lin, Guohui AU - Wishart, David S. T2 - Journal of Biomolecular NMR SN - 0925-2738 SN - 1573-5001 VL - 53 IS - 3 SP - 167 EP - 180 KW - protein; structure; quality; NMR; x-ray resolution AB - In protein X-ray crystallography, resolution is often used as a good indicator of structural quality. Diffraction resolution of protein crystals correlates well with the number of X-ray observables that are used in structure generation and, therefore, with protein coordinate errors. In protein NMR, there is no parameter identical to X-ray resolution. Instead, resolution is often used as a synonym of NMR model quality. Resolution of NMR structures is often deduced from ensemble precision, torsion angle normality and number of distance restraints per residue. The lack of common techniques to assess the resolution of X-ray and NMR structures complicates the comparison of structures solved by these two methods. This problem is sometimes approached by calculating “equivalent resolution” from structure quality metrics. However, existing protocols do not offer a comprehensive assessment of protein structure as they calculate equivalent resolution from a relatively small number (<5) of protein parameters. Here, we report a development of a protocol that calculates equivalent resolution from 25 measurable protein features. This new method offers better performance (correlation coefficient of 0.92, mean absolute error of 0.28 Å) than existing predictors of equivalent resolution. Because the method uses coordinate data as a proxy for X-ray diffraction data, we call this measure “Resolution-by-Proxy” or ResProx. We demonstrate that ResProx can be used to identify under-restrained, poorly refined or inaccurate NMR structures, and can discover structural defects that the other equivalent resolution methods cannot detect. DA - 2012/06/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9eb24cc5-5323-4ab6-8ddf-3942b852e5d0 ER - TY - JOUR TI - Supported and unsupported platinum catalysts prepared by a one-step dry deposition method and their oxygen reduction reactivity in acidic media DO - 10.1007/s10853-012-6324-3 AU - Roller, Justin AU - Neagu, Roberto AU - Orfino, Frank AU - Maric, Radenka T2 - Journal of Materials Science SN - 0022-2461 SN - 1573-4803 VL - 47 IS - 11 SP - 4604 EP - 4611 AB - The present study examines the physical and electrochemical properties of platinum particles generated by a combustion method for use in oxygen reduction on the cathode side of a proton exchange fuel cell (PEMFC). This method employs a one-step, open-atmosphere, and dry deposition technique called reactive spray deposition technology (RSDT). The objective of this study is to characterize the intrinsic activity of the platinum produced for incorporation into low-loading cathode electrodes in high performing membrane electrode assemblies (MEA). The process allows for independent real-time control of the carbon, platinum, and ionomer ratios in the final electrode. In this research work we examine the oxygen reduction reaction via a rotating disk three electrode set-up to understand the intrinsic activity of the as-sprayed platinum as well as platinum condensed onto a carbon support. The mass and specific activities were measured in a 0.1 M perchloric acid electrolyte under different deposition conditions and loading was verified by atomic emission spectroscopy inductively coupled plasma (AES-ICP). Microscopy results indicate that the platinum particle sizes are 5 nm (σ = 2.8 nm) in diameter while TEM and XRD show that the platinum generated by the process is pure and crystalline without bulk oxides or precursor material present. The initial rotating disk electrode result shows that the RSDT technique is capable of producing catalysts with an oxygen reduction mass activity at 0.9 V of 200 mA/mgPt rotating at 1600 rpm and 30 °C. The electrochemically active surface area approaches 120 m2/g for the platinum, carbon, and ionomer samples and the unsupported sample with only platinum has an active area of 92 m2/g. The rather larger surface area of the unsupported sample exists when the platinum is deposited as a highly porous nanostructured layer that allows for high penetration of reactant. DA - 2012/02/23 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 318ea9b1-2a3d-46df-9b7f-94b17e105959 ER - TY - JOUR TI - Precipitation of iron-rich intermetallic phases in Al-4.6Cu-0.5Fe-0.5Mn cast alloy DO - 10.1007/s10853-012-6279-4 AU - Liu, K. AU - Cao, X. AU - Chen, X.-G. T2 - Journal of Materials Science SN - 0022-2461 SN - 1573-4803 VL - 47 IS - 10 SP - 4290 EP - 4298 AB - The solidification of Al-4.6Cu-0.5Fe-0.5Mn (206 type) cast alloy has been studied using Thermal Analysis, Differential Scanning Calorimeter, Scanning Electron Microscopy, Electron Back-Scattered Diffraction (EBSD), and Transmission Electron Microscopy (TEM). It is interesting to note that an iron-rich intermetallic phase, Al3(FeMn), is experimentally observed to be dominantly present in the fully solidified cast structure of the experimental 206 cast alloy, in addition to β-Fe (Al7Cu2(FeMn)/Al7Cu2Fe) phase. Al3(FeMn) phase is formed through a eutectic reaction approximately at 640 °C during solidification, possibly resulting from the phase selection and segregation of Fe in liquid Al. The presence of the Al3(FeMn) phase has been confirmed by both EBSD and TEM. It is also found that both β-Fe and Al6(FeMn) are possible to nucleate on Al3(FeMn), as confirmed by the calculated low planar disregistries. The possible solidification reactions have been established for 206-type cast alloy at 0.5%Fe. DA - 2012/01/26 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 20baffc6-19d5-4422-86df-3b6fac803efd ER - TY - JOUR TI - Adhesive surface interactions of cellulose nanocrystals from different sources DO - 10.1007/s10853-012-6247-z AU - Lahiji, Roya R. AU - Boluk, Yaman AU - McDermott, Mark T2 - Journal of Materials Science SN - 0022-2461 SN - 1573-4803 VL - 47 IS - 9 SP - 3961 EP - 3970 AB - Adhesion plays an important role in the final properties of nanocomposites. This study explored the surface interaction of cellulose nanocrystals (CNCs) and the effect of CNC sources on adhesion between individual CNCs and the Si tip of an AFM cantilever using a force mapping technique called FMap. The adhesion between CNCs and a Si tip from five different sources has been studied: cotton, Whatman filter paper, hemp, softwood chemical kraft pulp, and softwood-dissolving pulp (alistaple). Mica was used as the background substrate to act as an internal standard. This study’s findings suggest that adhesion is not the same for all CNCs. Transmission electron microscopy and atomic force microscopy were used to determine the size and shape of each CNC. The experimental quantitative data showed that adhesion between CNCs and the Si tip has a close correlation with the diameter of the CNCs. X-ray photoelectron spectroscopy confirmed the presence of sulfate groups on the surface of the CNCs and a correlation between adhesion and surface chemistry of the CNCs was observed. DA - 2012/01/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 46003444-0fa1-4c00-acb4-49ded35476bb ER - TY - JOUR TI - Five new galactolipids from the freshwater microalga Porphyridium aerugineum and their nitric oxide inhibitory activity DO - 10.1007/s10811-012-9935-9 AU - Banskota, Arjun H. AU - Stefanova, Roumiana AU - Sperker, Sandra AU - Melanson, Ronald AU - Osborne, Jane A. AU - O’Leary, Stephen J. B. T2 - Journal of Applied Phycology SN - 0921-8971 SN - 1573-5176 VL - 25 IS - 4 SP - 951 EP - 960 KW - Porphyridium aerugineum; rhodophyta; galactolipid; monogalactosyldiacylglycerol (MGDG); digalactosyldiacylglycerol (DGDG); nitric oxide; inducible nitric oxide synthase AB - Chemical investigation of the freshwater rhodophyte microalga Porphyridium aerugineum led to the isolation of five new galactolipids, namely, (2S)-1-O-eicosapentaenoyl-2-O-arachidonoyl-3-O-β-d-galactopyranosylglycerol (1), (2S)-1-O-eicosapentaenoyl-2-O-linoleoyl-3-O-β-d-galactopyranosylglycerol (2), (2S)-1-O-arachidoyl-2-O-palmitoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (6), (2S)-1-O-eicosapentaenoyl-2-O-arachidoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (7), and (2S)-1-O-eicosapentaenoyl-2-O-linoleoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (8) together with five known galactolipids. The stereo-structures of all new galactolipids were elucidated by spectroscopic analyses and both enzymatic and chemical degradation methods. This is the first report of galactolipids from P. aerugineum. The newly isolated galactolipids showed strong and dose-dependent nitric oxide (NO) inhibitory activity against lipopolysaccharide-induced NO production in RAW264.7 macrophage cells. Both galactolipids 1 and 2 possessed stronger NO inhibitory activity than N G-methyl-l-arginine acetate salt, a well-known NO inhibitor used as a positive control. Further study suggested that these galactolipids inhibit NO production through downregulation of inducible nitric oxide synthase expression. DA - 2012/11/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 440c6532-af8d-49ff-acea-7ac002c185c0 ER - TY - JOUR TI - Small molecules containing hetero-bicyclic ring systems compete with UDP-Glc for binding to WaaG glycosyltransferase DO - 10.1007/s10719-012-9411-4 AU - Landström, Jens AU - Persson, Karina AU - Rademacher, Christoph AU - Lundborg, Magnus AU - Wakarchuk, Warren AU - Peters, Thomas AU - Widmalm, Göran T2 - Glycoconjugate Journal SN - 0282-0080 SN - 1573-4986 VL - 29 IS - 7 SP - 491 EP - 502 KW - glycosyltransferase; inhibitor; NMR; molecular modeling; screening AB - The α-1,3-glucosyltransferase WaaG is involved in the synthesis of the core region of lipopolysaccharides in E. coli. A fragment-based screening for inhibitors of the WaaG glycosyltrasferase donor site has been performed using NMR spectroscopy. Docking simulations were performed for three of the compounds of the fragment library that had shown binding activity towards WaaG and yielded 3D models for the respective complexes. The three ligands share a hetero-bicyclic ring system as a common structural motif and they compete with UDP-Glc for binding. Interestingly, one of the compounds promoted binding of uridine to WaaG, as seen from STD NMR titrations, suggesting a different binding mode for this ligand. We propose these compounds as scaffolds for the design of selective high-affinity inhibitors of WaaG. Binding of natural substrates, enzymatic activity and donor substrate selectivity were also investigated by NMR spectroscopy. Molecular dynamics simulations of WaaG were carried out with and without bound UDP and revealed structural changes compared to the crystal structure and also variations in flexibility for some amino acid residues between the two WaaG systems studied. DA - 2012/06/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0f08e56f-847a-46e3-90b0-5c5469a5693b ER - TY - JOUR TI - Fire resistance of wood truss floor assemblies DO - 10.1007/s10694-012-0311-8 AU - Sultan, Mohamed A. T2 - Fire Technology SN - 0015-2684 SN - 1572-8099 VL - December 2012 KW - wood truss; floor assemblies; fire resistance; insulation; resilient channel; concrete topping AB - This paper presents and discusses the factors that affect the fire resistance performance of lightweight wood truss floor assemblies protected with two layers of Type X gypsum board ceiling finishes. Fifteen full-scale fire resistance floor experiments were conducted using the CAN/ULC S-101 fire resistance standard which is similar to the ASTM E119. Parameters investigated in this study include the effects of insulation installation in floor cavity, insulation type, wood truss spacing, resilient channel installation, resilient channel spacing, wood truss width, wood truss chord orientation, wood truss web type, wood truss connection type and adding concrete topping above the sub-floor. The impact of these parameters on the fire resistance performance of the wood truss floor assemblies is discussed. The fire resistance of wood truss floors appears to be essentially governed by the wood trusses’ spacing for direct application of gypsum board to wood truss framing, insulation type and resilient channel installation and spacing. Other parameters are of secondary importance. DA - 2012/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2c86454a-5e49-4378-aaf8-afc3210642f4 ER - TY - JOUR TI - Evaluation of the onset of flashover in room fire experiments DO - 10.1007/s10694-012-0296-3 AU - Poulsen, Annemarie AU - Bwalya, Alex AU - Jomaas, Grunde T2 - Fire Technology SN - 0015-2684 SN - 1572-8099 VL - October 2012 KW - flashover; room fire experiments; thermal runaway; thermal feedback; thermal inertia AB - Two series of full scale room fire tests comprising 16 experiments are used for a study of the onset of flashover. The fire loads were varied and represented seven different commercial applications and two non-combustible linings with significantly different thermal inertia were used. The test results showed that by lowering the thermal inertia and thereby lowering the heat loss from the room and at the same time increasing the thermal feedback, a thermal runaway occurred before significant fire spread; but only for objects composed of a mixture of plastic/rubber/textiles and wood/celluloses. In these cases the onset of thermal runaway was found to occur at room temperatures in the range 300°C to 420°C, supporting that the room temperature at the onset of thermal runaway is strongly dependent on the thermal inertia. It also shows that the onset of thermal runaway cannot in all cases implicitly be predicted by the traditional flashover temperature criterion of 500°C to 600°C. For fire loads composed of pure wood/celluloses the onset of flashover occurred about the same time as fire spread irrespectively of linings and at significantly higher room temperatures (725°C). This can be explained by flammability parameters making wood/celluloses less sensitive to thermal feedback. DA - 2012/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 80c6a613-6cf3-4c31-8af9-6965e76d278a ER - TY - JOUR TI - Interaction between alkaline earth cations and oxo ligands : a DFT study of the affinity of Mg2+ for carbonyl ligands DO - 10.1007/s00894-012-1448-6 AU - Moreira da Costa, Leonardo AU - Stoyanov, Stanislav R. AU - Walkimar de M. Carneiro, José T2 - Journal of Molecular Modeling SN - 1610-2940 SN - 0948-5023 VL - 18 IS - 9 SP - 4389 EP - 4396 KW - Magnesium cation; Substituent effect; DFT; Interaction enthalpy AB - The affinities of Mg2+ for various substituted carbonyl ligands were determined at the DFT (B3LYP/6-31+G(d)) and semi-empirical (PM6) levels of theory. Two sets of carbonyl ligands were studied: monosubstituted [aldehydes R–CHO and RPh–CHO] and homodisubstituted [ketones R2C=O and (RPh)2C=O], where R = NH2, OCH3, OH, CH3, H, F, Cl, Br, CN, or NO2). In the (RPh)2CO case, the R group was bonded to the para position of a phenyl ring. The enthalpies of interaction between the ligands and a pentaaquomagnesium(II) complex were calculated to determine the affinity of each ligand for the Mg2+ cation and to correlate with geometrical and electronic parameters. These parameters exhibited the same trends for all of the ligands studied, showing that the affinity of Mg2+ for electron-donating ligands is higher than its affinity for electron-withdrawing ligands. In the complexes, electron-donating groups increase both the electrostatic and the covalent components of the Mg–ligand interaction. This behavior correlates with the Mg–O(carbonyl) distance and the ligand electron-donor strength. DA - 2012/05/16 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 27871c2c-cfc4-4b72-bea9-cd27d4e0c2dc ER - TY - JOUR TI - GQ1b-seronegative Fisher syndrome: clinical features and new serological markers DO - 10.1007/s00415-011-6360-y AU - Koga, Michiaki AU - Gilbert, Michel AU - Takahashi, Masaki AU - Li, Jianjun AU - Hirata, Koichi AU - Kanda, Takashi AU - Yuki, Nobuhiro T2 - Journal of Neurology SN - 0340-5354 SN - 1432-1459 VL - 259 IS - 7 SP - 1366 EP - 1374 KW - Fisher syndrome; Anti-GQ1b antibody; Campylobacter jejuni; Ganglioside complex; Lipooligosaccharide AB - IgG anti-GQ1b antibodies are a powerful serological marker for the diagnosis of Fisher syndrome (FS), but little is known regarding serological markers in FS patients that do not have the autoantibodies. The authors analyzed IgG antibodies against gangliosides other than GQ1b, ganglioside complexes, and ganglioside-like lipo-oligosaccharide (LOS) of Campylobacter jejuni isolates from FS patients. We identified 24 (12%) patients with GQ1b-seronegative FS among 207 FS patients who had been referred to our laboratory for anti-ganglioside antibody testing. Patients with GQ1b-seronegative FS were male and had a history of antecedent gastrointestinal illness more frequently than FS patients with IgG anti-GQ1b antibodies. Other clinical features during the illness were not distinguishing for GQ1b-seronegative FS. Four (17%) of 24 patients with GQ1b-seronegative FS had IgG antibodies against single gangliosides such as GM1b, GD1a, or GT1a. Antibodies against GM1 and GT1a complex were detected in four GQ1b-seronegative FS patients, three of whom did not have antibodies against single gangliosides. Mass spectrometry analysis showed that C. jejuni isolates from FS patients had GD1c-, GalNAc-GM1b-, or GalNAc-GD1c-like LOS, and not GQ1b-like LOS, highlighting the utility of examining serum antibodies against these ganglioside mimics in GQ1b-seronegative FS patients. Seven (29%) had IgG antibodies against the LOS from C. jejuni strains expressing GD1c-, GalNAc-GM1b-, or GalNAc-GD1c-like LOS. These findings suggest that IgG antibodies against GM1b, GD1c, GalNAc-GM1b, and ganglioside complexes are serological markers for GQ1b-seronegative Fisher syndrome. DA - 2012/01/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : de06e104-0065-4ee5-bc7a-9e7b5876fadb ER - TY - JOUR TI - Superhydrophobic surfaces fabricated by spray-coating micelle solutions of comb copolymers DO - 10.1007/s00396-012-2876-7 AU - Cui, Zhe AU - Ding, Jianfu AU - Scoles, Ludmila AU - Wang, Qingjun AU - Chen, Qingmin T2 - Colloid and Polymer Science SN - 0303-402X SN - 1435-1536 VL - 291 IS - 6 SP - 1409 EP - 1418 KW - Superhydrophobic; Micelle particles; Comb copolymer; Fluorinated polyether; Polystyrene AB - A series of comb copolymers (poly(arylene alkylene ether) (FPAE)-polystyrene (PS)) with a highly fluorinated FPAE main chain and narrow dispersed PS-grafted chains have been prepared. They are used to prepare micelle solutions in methanol/acetone (M/A) mixed solvents which are good for the FPAE main chains and poor for the PS-grafted chains. In these solutions, the PS-grafted chains form the cores and the FPAE main chains form the corona layers of micelle particles. Uniform micelle particles are achieved because of the narrow molecular weight dispersion of the PS chain length. The micelle solutions are spray-coated onto glass substrates to fabricate hydrophobic surfaces. It is found that the stability of the micelle particles increases with the length of the PS-grafted chains, which further influences the morphology and hydrophobicity of the spray-coated films. The effects of the M/A ratio and the copolymer concentration on the morphology and hydrophobicity of the coating surfaces are also studied. The results prove that a binary nano/microsurface structure is important to achieve a superhydrophobic surface with a low contact angle hysteresis. This binary structure is formed from conglomeration of micelle particles by spray coating the micelle solutions. The best sample reported in this paper has a static contact angle of 163° and a sliding angle of 5.9°. This fabrication procedure is facile, less time consuming, and easily applicable for large-scale surface treatment. DA - 2012/12/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cc34adc4-6f94-41b5-9ea3-32a88eecdc42 ER - TY - JOUR TI - Nanoscale laser-induced forward transfer through patterned Cr films DO - 10.1007/s00339-012-7159-0 AU - Sametoglu, V. AU - Sauer, V. AU - Tsui, Y. Y. T2 - Applied Physics A SN - 0947-8396 SN - 1432-0630 VL - 110 IS - 4 SP - 823 EP - 827 AB - The resolution enhancement of laser-induced forward transfer (LIFT) is investigated through the pre-patterning of Cr on the donor substrate. 85 nm dots are first patterned on a microscope slide, and an 800 nm wavelength and 130 fs pulse laser with a beam waist of ∼9 μm is used to transfer the Cr dots to an acceptor substrate. The threshold fluence is found to be ∼0.15 the threshold fluence of a similar continuous film, which is thought to be due to the fact that no force is needed to tear away Cr from the film itself, unlike in a continuous film experiment. Since the volume of the material limits the transfer feature sizes instead of the laser parameters, as in a continuous film system, minimum transferable feature diameters are significantly lower compared to the continuous film case. Also, the transferred feature diameters are not dependent on the laser parameters, so the diameters are consistent across a wide range of fluences. The force per unit area generated by the laser at threshold fluence is estimated to be ∼3 GPa, which is consistent with previous results in the literature. The simplified model that our pre-patterned Cr LIFT experiment represents would make it an ideal case for benchmarking molecular dynamics simulations of femtosecond laser ablation. DA - 2012/08/25 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ec5d1868-3cfd-4bd4-ae02-4c3867d65adc ER - TY - JOUR TI - Pulsed laser deposition of uniform semiconductor nanodot arrays DO - 10.1007/s00339-012-7158-1 AU - Gupta, Manisha AU - Sauer, Vincent AU - Tsui, Ying Yin T2 - Applied Physics A SN - 0947-8396 SN - 1432-0630 VL - 110 IS - 4 SP - 817 EP - 821 AB - Uniform arrays of silicon (Si), gallium arsenide (GaAs) and zinc oxide (ZnO) nanodots have been deposited using Pulsed Laser Deposition (PLD) technique combined with a contact mask consisting of nano-holes fabricated by E-beam lithography (EBL). These nanocrystalline semiconductor nanodots have been deposited by PLD on Si and GaAs substrates at room temperature. Characterization of the nanodots has been carried out using different techniques including X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), Auger Electron Spectroscopy (AES), and Raman spectroscopy. This work demonstrates a novel technique for deposition of uniform array of semiconductor nanostructures using a contact mask at room temperature for photonic applications. DA - 2012/08/24 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9ffde753-f0ee-4de0-a281-aa64b0771333 ER - TY - JOUR TI - Direct observation of low-temperature catalytic decomposition of H3BO3 shell in core/shell Ni/H3BO3 nanoparticles DO - 10.1007/s00339-012-6918-2 AU - Zhang, X. F. AU - Guan, P. F. AU - Dong, X. L. T2 - Applied Physics A SN - 0947-8396 SN - 1432-0630 VL - 108 IS - 2 SP - 487 EP - 489 AB - Decomposition of H3BO3 to B2O3 in core/shell Ni/H3BO3 nanoparticles was in situ recorded by transmission electron microscope as the irradiation time. The direct observation provides compelling evidence of the synergetic effect of the Ni core and the H3BO3 shell, revealing the catalytic mechanisms of metal nanostructures that induce the decomposition at 124 °C, lower than the bulk counterpart at 300 °C. This phenomenon can be theoretically explained by considering the weakening of B–O bond at the Ni–H3BO3 interface, and has important implications in understanding the lubricant behavior of H3BO3 in frictional wear. DA - 2012/04/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : eeca4a59-ffa7-4474-a088-47e6f79f437d ER - TY - JOUR TI - High-dielectric losses in stabilized γ-iron/graphite nanocomposites DO - 10.1007/s00339-011-6572-0 AU - Zhang, X. F. AU - Guan, P. F. AU - Medwig, J. AU - Dong, X. L. T2 - Applied Physics A SN - 0947-8396 SN - 1432-0630 VL - 106 IS - 3 SP - 589 EP - 595 AB - γ-iron and γ-iron/graphite nanoparticles were synthesized by a non-equilibrium cooling arc-discharge method. Experimental extinction spectra exhibit unexpected dielectric resonance of γ-iron nanoparticles at the microwave frequency, presenting the first metallic nanostructure of the high-dielectric loss. We further construct a multi-dielectric loss structure, with the enhanced dielectric loss factor of 0.7–0.9, by encapsulating the γ-iron into onion-like graphite nanoshells. DA - 2012/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3afb899c-338b-4d5b-b9a4-dbf837a91c39 ER - TY - JOUR TI - An evaluation of several in-lake restoration techniques to improve the water quality problem (eutrophication) of Saint-Augustin Lake, Quebec, Canada DO - 10.1007/s00267-012-9840-7 AU - Galvez-Cloutier, Rosa AU - Saminathan, Sumathi K. M. AU - Boillot, Clotilde AU - Triffaut-Bouchet, Gaëlle AU - Bourget, Alexandre AU - Soumis-Dugas, Gabriel T2 - Environmental Management SN - 0364-152X SN - 1432-1009 VL - 49 IS - 5 SP - 1037 EP - 1053 KW - eutrophication; phosphorus; integrated watershed management plan; restoration technique; water quality; microcosm assay tests AB - Increasing phosphorus (P) content and decreasing water quality of Saint-Augustin Lake, Quebec City, Canada, has led to implementation of an Integrated Watershed Management Plan to restore the lake. As a part of the plan, the effects of different restoration techniques on lake water quality and biological community (i.e., biological compatibility) were assessed during an isolated water enclosure study and laboratory microcosm assay, respectively. The restoration techniques include: (i) coagulation of P by alum only (20 mg L−1), (ii) active capping of sediments using a calcite layer of 10 cm, and (iii) a complete method involving both alum coagulation and calcite capping. The results showed that the total P (TP) was greatly decreased (76–95 %) by alum + calcite, followed by calcite only (59–84 %). Secchi depth was 106 % greater and chlorophyll a concentrations were declined by 19–78 % in the enclosure which received both alum and calcite. Results of the biological compatibility test showed that total phytoplankton biomass declined by 31 % in microcosms composed of alum + calcite. No significant (P > 0.05) toxic effect was found on the survival of Daphnia magna and Hyalella azteca in both alum only and alum + calcite microcosms. Although the alum + calcite technique impaired the survival of Chironomus riparius, the midge emergence was much higher compared to alum only and control. Overall, the alum + calcite application was effective in controlling P release from sediment and lowering water column P concentrations, and thus improving the water quality and aquatic life of Saint-Augustin Lake. However, the TP concentrations are still higher than the critical limit (20 μg L−1) for aquatic life and the water column remained in the eutrophic state even after treatment. Increased TP concentrations, to higher than ambient levels of the lake, in the water column of all four enclosures, due to bioturbation artefact triggered by the platform installation, likely cause insufficient dosages of alum and/or calcite applied and reduced their effectiveness. DA - 2012/04/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 850b1462-6add-4410-9a6e-ded81d8c2765 ER - TY - JOUR TI - Effect of cholesterol on the lateral nanoscale dynamics of fluid membranes DO - 10.1007/s00249-012-0826-4 AU - Armstrong, Clare L. AU - Barrett, Matthew A. AU - Hiess, Arno AU - Salditt, Tim AU - Katsaras, John AU - Shi, An-chang AU - Rheinstädter, Maikel C. T2 - European Biophysics Journal SN - 0175-7571 SN - 1432-1017 VL - 41 IS - 10 SP - 901 EP - 913 KW - Lipid membrane; Cholesterol; Lateral membrane dynamics; Nanoscale dynamics; Liquid-ordered phase; Inelastic neutron scattering; Dispersion relation AB - Inelastic neutron scattering was used to study the effect of 5 and 40 mol% cholesterol on the lateral nanoscale dynamics of phospholipid membranes. By measuring the excitation spectrum at several lateral q || values (up to q || = 3 Å−1), complete dispersion curves were determined of gel, fluid and liquid-ordered phase bilayers. The inclusion of cholesterol had a distinct effect on the collective dynamics of the bilayer’s hydrocarbon chains; specifically, we observed a pronounced stiffening of the membranes on the nanometer length scale in both gel and fluid bilayers, even though they were experiencing a higher degree of molecular disorder. Also, for the first time we determined the nanoscale dynamics in the high-cholesterol liquid-ordered phase of bilayers containing cholesterol. Namely, this phase appears to be “softer” than fluid bilayers, but better ordered than bilayers in the gel phase. DA - 2012/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : becdb5c0-0e23-4b1c-8259-18123364a5fa ER - TY - CHAP TI - PVT characterization of polymeric nanocomposites AU - Utracki, Leszek A. T2 - Characterization Techniques for Polymer Nanocomposites SN - 978-3-527-33148-2 SP - 75 DA - 2012 PY - 2012 PB - Wiley LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 36c1d7fa-4c2e-44a3-9f95-9e4211192862 ER - TY - JOUR TI - Systems biology methods help develop a better understanding of hepatitis C virus-induced liver injury DO - 10.1002/hep.25727 AU - Singaravelu, Ragunath AU - Nasheri, Neda AU - Sherratt, Allison AU - Pezacki, John Paul T2 - Hepatology SN - 0270-9139 VL - 56 IS - 1 SP - 1 EP - 4 DA - 2012/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0b145408-c2cd-42ee-a0a1-1d37a0b50c7c ER - TY - JOUR TI - Spatial MEG Laterality maps for language : clinical applications in epilepsy DO - 10.1002/hbm.22024 AU - D'arcy, Ryan C. N. AU - Bardouille, Timothy AU - Newman, Aaron J. AU - Mcwhinney, Sean R. AU - Debay, Drew AU - Sadler, R. Mark AU - Clarke, David B. AU - Esser, Michael J. T2 - Human Brain Mapping SN - 1065-9471 VL - 34 IS - 8 SP - 1749 EP - 1760 KW - magnetoencephalography; Wada test; presurgical functional mapping; neurological planning; language;memory; cognition AB - Functional imaging is increasingly being used to provide a noninvasive alternative to intracarotid sodium amobarbitol testing (i.e., the Wada test). Although magnetoencephalography (MEG) has shown significant potential in this regard, the resultant output is often reduced to a simplified estimate of laterality. Such estimates belie the richness of functional imaging data and consequently limit the potential value. We present a novel approach that utilizes MEG data to compute “complex laterality vectors” and consequently “laterality maps” for a given function. Language function was examined in healthy controls and in people with epilepsy. When compared with traditional laterality index (LI) approaches, the resultant maps provided critical information about the magnitude and spatial characteristics of lateralized function. Specifically, it was possible to more clearly define low LI scores resulting from strong bilateral activation, high LI scores resulting from weak unilateral activation, and most importantly, the spatial distribution of lateralized activation. We argue that the laterality concept is better presented with the inherent spatial sensitivity of activation maps, rather than being collapsed into a one-dimensional index. DA - 2012/03/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 29e903e6-b0e1-430b-8f96-82a83ef6126e ER - TY - JOUR TI - A photonic-microfluidic integrated device for reliable fluorescence detection and counting DO - 10.1002/elps.201200311 AU - Watts, Benjamin R. AU - Zhang, Zhiyi AU - Xu, Chang Qing AU - Cao, Xudong AU - Lin, Min T2 - Electrophoresis SN - 0173-0835 VL - 33 IS - 21 SP - 3236 EP - 3244 KW - Fluorescence detection; Integrated optics; Microbeads; Microfluidic devices AB - A photonic-microfluidic integrated device is demonstrated with excellent and reliable fluorescence detection performance. CV values of 8% for 2.5-μm beads and 14% for 6-μm beads were achieved through the correct deployment of carefully formed excitation beam shapes via integrated on-chip optics even without the use of 3D hydrodynamic focusing or a high-quality laser source and single mode beam propagation. The devices are fabricated in a monolithic planar fashion using a system of microlenses and waveguides integrated with microfluidic channels on-chip and packaged using a high-quality and low-cost channel sealing and high-performance interconnecting technology developed from our earlier works. Beam geometry in the excitation region is shown to affect the variation of fluorescence intensity from specimens, hence configurations of beam geometry targeted for a specific bead sizes are examined to ensure proper deployment of the lens designs. The formed high-quality optical excitation regions ensure reliable detection even with relaxed hydrodynamic focusing to ensure applicability with multiple specimen sizes. Device performance with each bead size was found to be acceptable for a range of beam geometries with a different ideal configuration for each bead size. These device designs help to form a device that will supplement conventional flow cytometry in point-of-care and remote detection applications by performing specific detections with an inexpensive and replaceable device. DA - 2012/10/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 648ff702-86c7-4951-a7a4-797e976a7d71 ER - TY - JOUR TI - Integrated electrokinetic sample fractionation and solid-phase extraction in microfluidic devices DO - 10.1002/elps.201200286 AU - Wang, Zhen AU - Jemere, Abebaw B. AU - Harrison, D. Jed T2 - Electrophoresis SN - 0173-0835 VL - 33 IS - 21 SP - 3151 EP - 3158 KW - Capillary electrophoresis; Electrokinetic; Fractionation; Microfluidics; Solid-phase extraction AB - A microfluidic device that performs “in space” sample fractionation, collection, and preconcentration for proteomics is described. Effluents from a 2.75 mm long fractionation channel, focused via sheath flow, were sequentially delivered into an array of 36-collection channels containing monolithic polymer beds for SPE. Optimum conditions for the device design, and simultaneous photolytic fabrication of 36 monolithic columns in the 36 channels, as well as for their proper performance in electrokinetic sample fractionation and collection are described. A hydrophobic butyl methacrylate-based monolithic porous polymer was copolymerized with an ionizable monomer, acryloamido-methyl-propane sulfonate, to form a polymer monolith for SPE that also sustains cathodic electroosmotic flow. The SPE bed was made deep enough to greatly reduce the linear flow rate within the bed, in order to compensate for the lower electroosmotic mobility of the cationically charged SPE bed relative to the glass walled device. Under these conditions, electrokinetic fractionation of a protein sample resulted in tightly focused sample zones delivered into each of the 36-channel polymer beds with no observed crosscontamination. Monolithic columns showed reproducible performance with preconcentration factor of 30 for 2 min loading time. The ability to fractionate, collect, and preconcentrate samples on a microfluidic platform will be especially useful for automated or continuous operation of these devices in proteomics research. DA - 2012/09/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7ad8cbe9-3bdb-434c-8743-bffca6756860 ER - TY - JOUR TI - Thiogalactopyranosides are resistant to hydrolysis by α-galactosidases DO - 10.1002/cbic.201200155 AU - Adlercreutz, Dietlind AU - Yoshimura, Yayoi AU - Mannerstedt, Karin AU - Wakarchuk, Warren W. AU - Bennett, Eric P. AU - Dovichi, Norman J. AU - Hindsgaul, Ole AU - Palcic, Monica M. T2 - ChemBioChem SN - 1439-4227 VL - 13 IS - 11 SP - 1673 EP - 1679 KW - fluorescent probes;glycosidases;hydrolytic stability;thiogalactosides AB - Fluorescently tagged glycosides containing terminal α(1→3) and α(1→4)-linked thiogalactopyranosides have been prepared and tested for resistance to hydrolysis by α-galactosidases. Eight fluorescent glycosides containing either galactose or 5-thiogalactose as the terminal sugar were enzymatically synthesized using galactosyltransferases, with lactosyl glycosides as acceptors and UDP-galactose or UDP-5′-thiogalactose, respectively, as donors. The glycosides were incubated with human α-galactosidase A (CAZy family GH27, a retaining glycosidase), Bacteroides fragilis α-1,3-galactosidase (GH110, an inverting glycosidase), or homogenates of MCF-7 human breast cancer cells or NG108-15 rat glioma cells. Substrate hydrolysis was monitored by capillary electrophoresis with fluorescence detection. All compounds containing terminal O-galactose were readily degraded. Their 5-thiogalactose counterparts were resistant to hydrolysis by human α-galactosidase A and the enzymes present in the cell extracts. B. fragilis α-1,3-galactosidase hydrolyzed both thio- and O-galactoside substrates; however, the thiogalactosides were hydrolyzed at only 1–3 % of the rate of O-galactosides. The hydrolytic resistance of 5-thiogalactose was also confirmed by an in vivo study using cells in culture. The results suggest that 5-thiogalactosides may be useful tools for the study of anabolic pathways in cell extracts or in single cells. DA - 2012/06/27 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cfac01bb-6b60-495a-8b48-0a150d6e1ca6 ER - TY - JOUR TI - Enhance fire resistance of cellulosic fibers for green polymer composites AU - Ngo, T.-D. AU - Ton That, M.-T. AU - Hu, W. T2 - SAMPE Tech 2012 Conference and Exhibition : North Charleston, South Carolina, October 22-25, 2012 : Navigating the global landscape for the new composites T3 - Society for the Advancement of material and Process Engineering (SAMPE tech 2012), 22-25 October 2012, North Charleston, South Carolina, USA DA - 2012/10/25 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 14909c70-5c9d-48c3-b74a-5681486072c1 ER - TY - JOUR TI - A laser position sensing system for the study of accelerometer rocking motion due to cable strain AU - Wu, Lixue T2 - Proceedings of the 18th International Congress on Sound and Vibration 2011 T3 - 18th International Congress on Sound and Vibration 2011 (ICSV 18), 10-14 July 2011, Rio de Janeiro, Brazil SN - 9781618392596 VL - 3 SP - 1877 SP - 2501 EP - 2508 DA - 2012/01 PY - 2012 PB - Curran LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 174cc3da-a2b5-48a5-b1b4-e1ddb2d9f969 ER - TY - JOUR TI - Composite spectra: XVIII HR 6497, a triple system containing a baffling double secondary DO - 10.1002/asna.201211703 AU - Griffin, R. E. M. AU - Griffin, R. F. T2 - Astromische Nachrichten (Astronomical Notes) VL - 333 IS - 7 SP - 613 EP - 626 KW - binaries: spectroscopic; stars: individual: (HR 6497); stars: fundamental parameters AB - We present a full description of, and parameters for, the component stars in the triple-lined composite-spectrum system HR 6497. Both the outer and the inner orbits have already been computed with fair accuracy, but the improved orbits resulting from this new analysis have precisions that are up to an order of magnitude tighter. By applying the proven technique of spectral subtraction to a large sample of new, high-quality spectra we separate the spectra of the inner pair cleanly for the first time, and show that it has characteristics which cannot be explained at all easily by conventional models. Since the inner pair are separated by only 4 times their own radii, we expect their rotations to be synchronized to their orbital revolution, or close to 28 km/s, but in fact they have almost no visible rotation at all. The Mg II line at λ 4481 Å, itself a close doublet with a separation of 0.2 Å, is clearly resolved in the spectra of both components of the inner system. Such resolution is extremely rare in our experience, and we are unable to suggest a satisfactory explanation for it DA - 2012/08/01 PY - 2012 PB - Wiley LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 113ccd6f-32be-422c-9a6a-9866e5993d4f ER - TY - JOUR TI - Fluorescent silver nanoclusters as effective probes for highly selective detection of mercury(II) at parts-per-billion levels DO - 10.1002/asia.201200033 AU - Wang, Chuanxi AU - Xu, Lin AU - Wang, Yu AU - Zhang, Dan AU - Shi, Xiaodong AU - Dong, Fengxia AU - Yu, Kui AU - Lin, Quan AU - Yang, Bai T2 - Chemistry - An Asian Journal SN - 1861-4728 VL - 7 IS - 7 SP - 1652 EP - 1656 KW - nanoclusters; fluorescent probes; mercury; selective detection; silver AB - Facile preparation of water-soluble and fluorescent Ag nanoclusters (NCs) stabilized by glutathione at room temperature is described. Although the glutathione layer was introduced to prevent the silver nanoparticles from decomposition and increase their water solubility, this simple surface optimization resulted in surprisingly high efficiency of selective Hg2+ sensing, where the limit of detection (LOD) was as low as 10−10 m (0.02 ppb, 0.1 nm). This result revealed a simple and practical strategy for Hg2+ detection using fluorescent Ag NCs as sensor probe, with the lowest detecting limits reported to date. DA - 2012/04/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 789f70dd-d7dc-41f0-aa45-78d4bc6f9d0d ER - TY - JOUR TI - Durability design of high-performance concrete bridge decks using fine lightweight aggregate and shrinkage-reducing admixture AU - Cusson, Daniel AU - Margeson, Jim T2 - The Economics, Performance and Sustainability of Internally Cured Concrete (ACI Fall Session) T2 - ACI Special Publication T3 - ACI Fall Convention: The Economics, Performance and Sustainability of Internally Cured Concrete, Oct 21, 2012, Toronto, Ontario VL - 290 KW - bridge decks; high-performance concrete; internal curing; lightweight aggregate; shrinkage-reducing admixture; durability; service life prediction; life-cycle cost analysis AB - Highway bridges and parking structures, subject to coupled effects of mechanical loads and corrosion, often show early signs of distress such as concrete cracking and rebar corrosion leading to reduced structural performance and shortened service life. One solution to this problem is to use low-shrinkage low-permeability high-performance concrete (HPC) for bridge decks exposed to de-icing salts and severe loading conditions. A new HPC was formulated to achieve low shrinkage and low permeability, high early-strength, and 28-day compressive strength over 60 MPa (8,700 psi). Its mechanical performance and durability were tested both in the lab and field under severe test conditions, including restrained shrinkage, cycling loading, freezing and thawing cycles, and application of de-icing salts. Prediction models were developed and calibrated to predict structural performance and service life of concrete bridge decks under severe exposure conditions. Prediction models indicate that bridge decks designed with low-shrinkage HPC can achieve a service life up to 100 years. Compared to normal concrete decks, short-to-medium span bridge decks using low-shrinkage HPC could be built at a comparable initial construction cost, but at less than 35 percent of the life-cycle cost. DA - 2012/10/21 PY - 2012 PB - American Concrete Institute LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b82228d0-bc81-4963-8e74-a10f2caae11b ER - TY - JOUR TI - Distinct models of induced hyperactivity in zebrafish larvae DO - 10.1016/j.brainres.2012.02.022 AU - Ellis, Lee David AU - Seibert, Jake AU - Soanes, Kelly Howard T2 - Brain Research SN - 00068993 VL - 1449 SP - 46 EP - 59 KW - Zebrafish KW - disease model KW - hyperactivity KW - pentylenetrazole KW - aconitine KW - 4-aminopyridine AB - The analysis of behavioural hyperactivity can provide insights into how perturbations in normal activity may be linked to the altered function of the nervous system and possibly the symptoms of disease. As a small vertebrate zebrafish have numerous experimental advantages that are making them a powerful model for these types of studies. While the majority of behavioural studies have focused on adult zebrafish, it has become apparent that larvae can also display complex stereotypical patterns of behaviour. Here we have used three compounds (pentylenetetrazole (PTZ), aconitine and 4-aminopyridine) that have different neuronal targets (GABA, sodium and potassium channels), to induce distinct patterns of hyperactivity in larvae. Our studies have revealed that each compound produces a number of distinct concentration-dependent activity patterns. This work has shown for the first time that at sub-convulsive concentrations, PTZ can reverse the normal behavioural response to alternating periods of light and dark in zebrafish larvae. It also appears that both PTZ and 4-aminopyridine produce distinct changes in the normal startle response patterns immediately following light/dark transitions that may be the result of an elevation in stress/anxiety. Aconitine produces a general elevation in activity that eliminates the normal response to light and dark. In addition to differences in the patterns of behaviour each compound also produces a unique pattern of c-fos (an immediate early gene) expression in the brain. While more work is required to make direct links between region specific neuronal activity and individual behaviours, these models provide a framework with which to study and compare mechanistically different types of inducible behaviours. DA - 2012/02/16 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2e2e7b3a-c346-4980-9a20-6e4a412882d4 ER - TY - JOUR TI - The cell motility modulator Slit2 is a potent inhibitor of platelet function DO - 10.1161/CIRCULATIONAHA.112.105452 AU - Patel, Sajedabanu AU - Huang, Yi-Wei AU - Reheman, Adili AU - Pluthero, Fred G. AU - Chaturvedi, Swasti AU - Mukovozov, Ilya M. AU - Tole, Soumitra AU - Liu, Guang-Ying AU - Li, Ling AU - Durocher, Yves AU - Ni, Heyu AU - Kahr, Walter H. A. AU - Robinson, Lisa A. T2 - Circulation SN - 0009-7322 VL - 126 SP - 1385 EP - 1395 KW - blood cells; blood platelets; thrombosis AB - Background—Vascular injury and atherothrombosis involve vessel infiltration by inflammatory leukocytes, migration of medial vascular smooth muscle cells to the intimal layer, and ultimately acute thrombosis. A strategy to simultaneously target these pathological processes has yet to be identified. The secreted protein, Slit2, and its transmembrane receptor, Robo-1, repel neuronal migration in the developing central nervous system. More recently, it has been appreciated that Slit2 impairs chemotaxis of leukocytes and vascular smooth muscle cells toward diverse inflammatory attractants. The effects of Slit2 on platelet function and thrombus formation have never been explored. DA - 2012/08/03 PY - 2012 PB - American Heart Association LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2ea65dd3-828d-4158-b258-a90be168c360 ER - TY - JOUR TI - Microencapsulated mammalian cells for simultaneous production of VEGF165b and IFNα DO - 10.3109/10731199.2011.560120 AU - Afkhami, Fatemeh AU - Durocher, Yves AU - Prakash, Satya T2 - Artificial Cells, Nanomedicine, and Biotechnology VL - 40 IS - 1-2 SP - 1 EP - 6 KW - artificial cell; microcapsule; co-encapsulation; angiogenesis; IFNα; VEGF165b; alginate; poly-L-lysine; cell therapy AB - Targeted and simultaneous delivery VEGF165b and IFN alpha in anti-angiogenic and other applications could offer several advantages. For this a system was design using artificial cell alginate-poly-L-lysine- alginate (APA) microcapsules. Result confirms the ability of this system for simultaneous production of these proteins for 28-days. The IFN alpha on a 3 days period increased from 8 ± 0.36 μg/ml at day 10 to 27 ± 2.4 μg/ml at day 16 and then dropped to 6.5 ± 0.5 μg/ml. The VEGF165b on a 3 days period increased from 2.7 ± 0.7 μg/ml at day 10 to 6.9 ± 1 μg/ml at day 16. DA - 2012/02 PY - 2012 PB - Informa Healthcare LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 77acc44e-2dce-4e5e-a1a9-7df93a98f5a1 ER - TY - JOUR TI - Optical model for prismatic glazing (1415-RP) DO - 10.1080/10789669.2012.736812 AU - Laouadi, Abdelaziz AU - Saber, Hamed H. AU - Galasiu, Anca D. AU - Arsenault, Chantal T2 - HVAC and R Journal VL - 19 IS - 1 SP - 63 EP - 75 AB - Prismatic glazing is found in many building applications, such as complex fenestration systems to control solar heat gains and glare and re-direct sunlight to building interior spaces and daylighting (and lighting) systems to enhance their optical and lighting performance. However, modeling and simulation of such prismatic glazing has been a very difficult task due to its versatile and complex geometrics. This article presents the development and validation of a simplified model to compute the optical characteristics and dominant directions of the transmitted and reflected beam rays of sawtooth-like prismatic glazing. The model was based on tracing the average ray and was extensively validated using third-party data derived from ray tracing computer simulations and measurement using integrating spheres and goniophotometers. The model's predictions for the transmittance and reflectance of single and double prismatic panes compared well overall within the accuracy of the third-party data over all incidence angles. DA - 2012/11/27 PY - 2012 PB - Taylor and Francis LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1ca732a8-28c0-450d-8f6c-9ed5ef1373d5 ER - TY - JOUR TI - Performance of ductile iron pipes. II : sampling scheme and inferring the pipe condition DO - 10.1061/(ASCE)IS.1943-555X.0000098 AU - Kleiner, Yehuda AU - Rajani, Balvant T2 - Journal of Infrastructure Systems SN - 1076-0342 SN - 1943-555X VL - 19 IS - 1 SP - 120 EP - 128 KW - Ductile iron pipe; Corrosion pits; Pipe sampling scheme; Pipe condition assessment AB - Ductile iron (DI) pipes have been used in North America since the late 1950s. This paper describes how understanding gained on the geometry of external corrosion pits is used to devise a sampling scheme and to infer the condition of ductile iron buried water mains. The companion paper describes the exhumation of varying lengths of ductile iron pipes in four North American water utilities. The exhumed pipes were cut into sections, sandblasted, and tagged. Soil samples extracted along the exhumed pipe were also provided. Pipe sections were scanned for external corrosion using a laser scanner to produce corrosion pit data sets. Statistical analyses were performed on geometric properties of corrosion pits such as pit depth, pit area, and pit volume. These analyses were developed further to assess the impact of the different soil characteristics on these pit properties. This paper describes the investigation of appropriate sampling schemes to represent the statistical properties of ductile iron pipe corrosion. With known statistical properties, an approach is developed to infer the condition of the pipe. DA - 2012/02/06 PY - 2012 PB - ASCE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 62f4fa25-a046-4079-99fa-f465fb184bd1 ER - TY - JOUR TI - Performance of ductile iron pipes. I : characterization of external corrosion patterns DO - 10.1061/(ASCE)IS.1943-555X.0000097 AU - Kleiner, Yehuda AU - Rajani, Balvant AU - Krys, Dennis T2 - Journal of Infrastructure Systems SN - 1076-0342 SN - 1943-555X VL - 19 IS - 1 SP - 108 EP - 119 KW - ductile iron pipes; corrosion pit; corrosion pit geometry; soil properties; probability distribution; sampling AB - Ductile iron pipes have been used in North America since the late 1950s. This paper describes research that endeavored to gain a thorough understanding of the geometry of external corrosion pits and the factors (e.g., soil properties, appurtenances, and service connections) that influence this geometry. This understanding is subsequently used in the companion paper to devise a sampling scheme and to infer the condition of ductile iron buried water mains. Soil corrosivity is not a directly measurable parameter, and pipe external corrosion is primarily a random phenomenon. The literature is replete with methods and systems that attempt to use soil properties (e.g., resistivity, pH, and redox potential) to quantify soil corrosivity and subsequently predict pipe corrosion. In this research, varying lengths of ductile iron pipes were exhumed by several North American water utilities. The exhumed pipes were cut into short sections, sandblasted, and tagged. Soil samples were also obtained at discrete locations along the exhumed pipe. Pipe sections were scanned for external corrosion using a specially developed laser scanner. Scanned corrosion data were processed using specially developed software to obtain information on pit depth, pit area, and pit volume. Statistical analyses were subsequently performed on these three geometrical attributes. Various soil characteristics were investigated to determine their impact on the geometric properties of the corrosion pits. Subsequently, a method is proposed to assess the condition of a ductile iron pipe, based on the geometry of corrosion pits of several samples extracted along the pipe. This paper describes the pipe exhumation, data preparation, and statistical analysis of corrosion pits. The companion paper describes a sampling scheme to infer pipe condition of ductile iron buried water mains. DA - 2012/02/06 PY - 2012 PB - ASCE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4bf7116d-aa18-4a2c-9a0e-8b6def5a135c ER - TY - JOUR TI - Characterization of the alkaloids in goldenseal (Hydrastis canadensis) root by high resolution Orbitrap LC-MSn DO - 10.1007/s00216-012-6539-9 AU - Le, Phuong Mai AU - McCooeye, Margaret AU - Windust, Anthony T2 - Analytical and Bioanalytical Chemistry SN - 1618-2642 SN - 1618-2650 VL - 405 IS - 13 SP - 4487 EP - 4498 KW - Hydrastis canadensis; alkaloid; structural characterization; LC-ESI-MSn AB - Liquid chromatography coupled to multistage mass spectrometry (LC-MSn) is being used increasingly in pharmaceutical research and for quality control in herbal medicines because of its superior sensitivity and selectivity. In this study, a rapid, high-resolution liquid chromatography-mass spectrometry (LC-MSn) method was developed to separate and identify alkaloids in the root extract of goldenseal, which is one of the 20 most popular herbal supplements used worldwide. In total, 28 alkaloids were separated and characterized including one novel compound and 21 identified, or tentatively identified, for the first time in goldenseal. The current high-resolution LC-MSn method provides a rapid and definitive means of profiling the composition of goldenseal root and will provide a useful tool in understanding the bioactivity of this medicinal plant. DA - 2012/12/24 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9721728d-c3cb-4c8c-9a70-0a675af99e53 ER - TY - JOUR TI - High-throughput quantitative analysis with cell growth kinetic curves for low copy number mutant cells DO - 10.1007/s00216-012-6328-5 AU - Xing, James Z. AU - Gabos, Stephan AU - Huang, Biao AU - Pan, Tianhong AU - Huang, Min AU - Chen, Jie T2 - Analytical and Bioanalytical Chemistry SN - 1618-2642 SN - 1618-2650 VL - 404 IS - 6-7 SP - 2033 EP - 2041 KW - RT-CES mutagenicity test; cell growth kinetic curve; high-throughput assay; low copy number mutant cell; baseline and threshold analyses AB - The mutation rate in cells induced by environmental genotoxic hazards is very low and difficult to detect using traditional cell counting assays. The established genetic toxicity tests currently recognized by regulatory authorities, such as conventional Ames and hypoxanthine guanine phosphoribosyl-transferase (HPRT) assays, are not well suited for higher-throughput screening as they require large amounts of test compounds and are very time consuming. In this study, we developed a novel cell-based assay for quantitative analysis of low numbers of cell copies with HPRT mutation induced by an environmental mutagen. The HPRT gene mutant cells induced by the mutagen were selected by 6-thioguanine (6-TG) and the cell’s kinetic growth curve monitored by a real-time cell electronic sensor (RT-CES) system. When a threshold is set at a certain cell index (CI) level, samples with different initial mutant cell copies take different amounts of time in order for their growth (or CI accumulation) to cross this threshold. The more cells that are initially seeded in the test well, the faster the cell accumulation and therefore the shorter the time required to cross this threshold. Therefore, the culture time period required to cross the threshold of each sample corresponds to the original number of cells in the sample. A mutant cell growth time threshold (MT) value of each sample can be calculated to predict the number of original mutant cells. For mutagenesis determination, the RT-CES assay displayed an equal sensitivity (p > 0.05) and coefficients of variation values with good correlation to conventional HPRT mutagenic assays. Most importantly, the RT-CES mutation assay has a higher throughput than conventional cellular assays. DA - 2012/09/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : df529995-c1f5-44ec-a47b-e55c8112623f ER - TY - JOUR TI - Laboratory x-ray powder diffraction DO - 10.1007/978-94-007-5580-2_6 AU - Whitfield, Pamela T2 - Uniting Electron Crystallography and Powder Diffraction T2 - NATO Science for Peace and Security Series B: Physics and Biophysics SN - 9789400755796 SP - 53 EP - 63 AB - Laboratory diffractometers form the introduction to powder diffraction for most researchers. On a basic level for phase ID, etc., one diffractometer is very much like another. However when configuring a system for more challenging and advanced experiments, a variety of options and choices confront the experimentalist. Rather than cover the basics of diffractometer operation and geometry we will discover how a good understanding of the concepts behind laboratory diffractometers and their components is vital to getting the best from a system and pushing the limits of what can be achieved with lab instrumentation. Laboratory instrumentation will never compete with the sheer power and resolution of a synchrotron beamline. However, by departing from the conventional setups, it can be surprising what may be achieved in-house without resorting to the delay and inconvenience of synchrotron beamtime proposals. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0843a673-8aaf-4816-aff9-74f8d9b6bae4 ER - TY - JOUR TI - Quantitative analysis of azaspiracids in Azadinium spinosum cultures DO - 10.1007/s00216-012-5849-2 AU - Jauffrais, Thierry AU - Herrenknecht, Christine AU - Séchet, Véronique AU - Sibat, Manoella AU - Tillmann, Urban AU - Krock, Bernd AU - Kilcoyne, Jane AU - Miles, Christopher O. AU - McCarron, Pearse AU - Amzil, Zouher AU - Hess, Philipp T2 - Analytical and Bioanalytical Chemistry SN - 1618-2642 SN - 1618-2650 VL - 403 IS - 3 SP - 833 EP - 846 KW - extraction procedure; extraction artefact; matrix effects; LC-MS/MS; azaspiracid methyl ester; dinoflagellate; liquid chromatography–mass spectrometry AB - Azaspiracids (AZAs) are secondary metabolites of Azadinium spinosum that can accumulate in shellfish and cause food poisoning when consumed. We describe here an analytical procedure for the determination of AZAs in cultures of A. spinosum with a focus on the formation of AZA methyl esters as artefacts during extraction and sample pre-treatment. A. spinosum cells were collected from bioreactor cultures using centrifugation or filtration. Different extraction procedures were evaluated for formation of methyl ester artefacts, yield, and matrix effects. Filtration of cultures using glass-fibre filters led to increased formation of methyl esters, and centrifugation is recommended for recovery of cells. The extraction solvent (methanol (MeOH), acetone, and acetonitrile (MeCN)) did not significantly affect the yield of AZAs as long as the organic content was 80% or higher. However, the use of MeOH as extraction solvent led to increased formation of methyl esters. AZA1 recovery over two successive extractions was 100% at the 95% confidence level for acetone and MeOH. In standard-addition experiments, no significant matrix effects were observed in extracts of A. spinosum or Azadinium obesum up to a sample size of 4.5 × 10^9 μm^3. Moreover, experiments carried out to clarify the formation and structure of methylated AZA analogues led to the description of two AZA methyl esters and to the correction of the chemical structures of AZAs29–32. DA - 2012/02/26 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f8da29fd-9997-4969-ba07-f2a29686080c ER - TY - JOUR TI - Calibration of isotope amount ratios by analysis of isotope mixtures DO - 10.1007/s00216-012-5785-1 AU - Meija, Juris T2 - Analytical and Bioanalytical Chemistry SN - 1618-2642 SN - 1618-2650 VL - 403 IS - 8 SP - 2071 EP - 2076 KW - metrology; mass spectrometry; isotope amount ratios AB - The question as to what constitutes a fully calibrated isotope amount ratio measurement still remains a topic of active research. For years, the definitive calibration approach has been by means of synthetic mixtures of highly enriched isotopes with known chemical purity to give gravimetrically defined ratios. This article outlines the core concepts and assumptions of this method and illustrates the recent developments in the practical metrology of isotope amount ratio measurements. DA - 2012/02/16 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5b75dff8-00e4-4f2b-bacf-77fa70767efd ER - TY - JOUR TI - Conduction modulation of π-stacked ethylbenzene wires on Si(100) with substituent groups DO - 10.1007/s00214-011-1085-7 AU - Smeu, Manuel AU - Wolkow, Robert A. AU - Guo, Hong T2 - Theoretical Chemistry Accounts SN - 1432-881X SN - 1432-2234 VL - 131 IS - 1 SP - 1085 EP - 1092 KW - molecular wire; NEGF–DFT; Substituent group; conductance modulation; electron transport; ethylbenzene wire AB - For the realization of molecular electronics, one essential goal is the ability to systematically fabricate molecular functional components in a well-controlled manner. Experimental techniques have been developed such that π-stacked ethylbenzene molecules can now be routinely induced to self-assemble on an H-terminated Si(100) surface at precise locations and along precise directions. Electron transport calculations predict that such molecular wires could indeed carry an electrical current, but the Si substrate may play a considerable role as a competing pathway for conducting electrons. In this work, we investigate the effect of placing substituent groups of varying electron donating or withdrawing strengths on the ethylbenzene molecules to determine how they would affect the transport properties of such molecular wires. The systems consist of a line of π-stacked ethylbenzene molecules covalently bonded to a Si substrate. The ethylbenzene line is bridging two Al electrodes to model current through the molecular stack. For our transport calculations, we employ a first-principles technique where density functional theory (DFT) is used within the non-equilibrium Green’s function formalism (NEGF). The calculated density of states suggest that substituent groups are an effective way to shift molecular states relative to the electronic states associated with the Si substrate. The electron transmission spectra obtained from the NEGF–DFT calculations reveal that the transport properties could also be extensively modulated by changing substituent groups. For certain molecules, it is possible to have a transmission peak at the Fermi level of the electrodes, corresponding to high conduction through the molecular wire with essentially no leakage into the Si substrate. DA - 2012/01/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7d02c9c5-3064-4839-ad73-a46d4d49a96d ER - TY - JOUR TI - The solvated interaction energy method for scoring binding affinities DO - 10.1007/978-1-61779-465-0_19 AU - Sulea, Traian AU - Purisima, Enrico O. T2 - Computational Drug Discovery and Design T2 - Methods in Molecular Biology; 819 SN - 978-1-61779-464-3 SP - 295 EP - 303 KW - binding free energy; scoring function; protein-ligand binding; molecular dynamics AB - The solvated interaction energy (SIE) is an end-point, physics-based scoring function for predicting ligand-binding affinities. It supplements the force-field interaction energy with the desolvation cost of binding. Parameters such as the solute dielectric constant, Born radii, a cavity term and an overall scaling coefficient and additive constant have been previously calibrated against a training set of 99 protein–ligand complexes. We describe the application of the method to estimating binding free energies from molecular dynamics trajectories of protein–ligand binding complexes. DA - 2012 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a9f3d349-72f5-4a79-845e-0967dd29c44b ER - TY - JOUR TI - Computational modeling of extended systems DO - 10.1007/s00214-011-1067-9 AU - Dilabio, Gino A. T2 - Theoretical Chemistry Accounts SN - 1432-881X SN - 1432-2234 VL - 131 IS - 1 SP - 1067 EP - 1068 KW - advances in computer architecture; synergy between nanoscience theory and experiment; molecular lines on silicon; nanoparticle-polymer nanocomposites; protein crystal structure modeling by density-functional theory AB - Advancements in computing architecture and in theoretical techniques allow for the modeling of complex, extended systems. This section of the 50th anniversary issue of Theoretical Chemistry Accounts highlights modeling work performed on nanostructured systems and underscores the enormous potential for synergy between theory and experiment in modern nanoscience. DA - 2012/01/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d62689cf-535b-4237-b7b0-a1d191ec9f0c ER - TY - JOUR TI - Results of the first North American comparison of absolute gravimeters, NACAG-2010 DO - 10.1007/s00190-011-0539-y AU - Schmerge, D. AU - Francis, O. AU - Henton, J. AU - Ingles, D. AU - Jones, D. AU - Kennedy, J. AU - Krauterbluth, K. AU - Liard, J. AU - Newell, D. AU - Sands, R. AU - Schiel, A. AU - Silliker, J. AU - Westrum, D. T2 - Journal of Geodesy SN - 0949-7714 SN - 1432-1394 VL - 86 IS - 8 SP - 591 EP - 596 KW - absolute gravimetry; gravimeter; GRAV-D; comparison; offset AB - The first North American Comparison of absolute gravimeters (NACAG-2010) was hosted by the National Oceanic and Atmospheric Administration at its newly renovated Table Mountain Geophysical Observatory (TMGO) north of Boulder, Colorado, in October 2010. NACAG-2010 and the renovation of TMGO are part of NGS’s GRAV-D project (Gravity for the Redefinition of the American Vertical Datum). Nine absolute gravimeters from three countries participated in the comparison. Before the comparison, the gravimeter operators agreed to a protocol describing the strategy to measure, calculate, and present the results. Nine sites were used to measure the free-fall acceleration of g. Each gravimeter measured the value of g at a subset of three of the sites, for a total set of 27 g-values for the comparison. The absolute gravimeters agree with one another with a standard deviation of 1.6 μGal (1 Gal ≡ 1 cm s −2). The minimum and maximum offsets are −2.8 and 2.7 μGal. This is an excellent agreement and can be attributed to multiple factors, including gravimeters that were in good working order, good operators, a quiet observatory, and a short duration time for the experiment. These results can be used to standardize gravity surveys internationally. DA - 2012/01/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b24411db-100e-4991-9764-063f4d3c9fe5 ER - TY - JOUR TI - Experimental study on the effect of varying focal offset distance on laser micropolished surfaces DO - 10.1007/s00170-012-4677-z AU - Chow, Michael T. C. AU - Bordatchev, Evgueni V. AU - Knopf, George K. T2 - The International Journal of Advanced Manufacturing Technology SN - 0268-3768 SN - 1433-3015 KW - laser micropolishing; focal offset distance; surface roughness; surface waviness AB - Laser micropolishing (LμP) is an innovative part-finishing process that reduces machining roughness by melting a thin layer of material on the micromilled surface using a focused laser beam. The quality of the final polished surface is dependent upon the part material, initial surface topography and roughness, and the energy density of the beam. The focal offset distance (FOD) is one critical parameter that controls the amount of energy delivered to the workpiece. The impact of varying the FOD on final laser-polished surface quality is investigated by performing a series of experiments on carefully prepared AISI H13 test samples with known initial surface roughness and waviness due to the milled track periodicity. Three well-defined polishing regimes were observed when adjusting the FOD for a Q-switched Nd/YAG LμP system between 1.3 and 2.9 mm. Given the same initial micromilled surface geometry, each LμP regime (i.e., short FOD, <1.8 mm; long FOD, >2.2 mm; and intermediate FOD) reduced the surface roughness and periodic waviness in a distinct manner. For a micromilled sample with a 33-μm periodicity, the LμP with FOD of >2.2 mm was determined to be the most effective regime by improving surface quality by 39.7 %. The affects of repetitive exposure to the beam and increasing the applied laser power on improving surface quality are also investigated for the 3 LμP regimes. DA - 2012/12/30 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f425adba-7b4b-4afe-8c36-6fb96901a78e ER - TY - JOUR TI - Experimental study of the effect of tool orientation in five-axis micro-milling of brass using ball-end mills DO - 10.1007/s00170-012-4549-6 AU - Fard, M. Javad Barakchi AU - Bordatchev, Evgueni V. T2 - The International Journal of Advanced Manufacturing Technology SN - 0268-3768 SN - 1433-3015 KW - micro-milling; five-axis; tool orientation; surface quality; cutting forces AB - The effect of tool orientation on the final surface geometry and quality in five-axis micro-milling of brass using ball-end mills is investigated. Straight grooves with a semicircular cross section are cut with different tool inclination and tilt angles, and the resulting surfaces are characterized using an optical profilometer and microscope. Micro-milling cutting forces are recorded synchronously with spindle electric current and cutting motions in order to investigate the correlation between the tool orientation and the achieved surface quality. Results of various cutting experiments and analysis of the final surface geometry show that varying the tool orientation reduces rubbing of the material at the bottom of the grooves, which often occurs in ball-end milling of brass, and improves the final surface quality. The experimental analysis for surface roughness shows that applying a tool inclination angle of 15° can considerably improve the surface roughness at the bottom of the grooves. Analysis of static and averaged peak-to-valley (P-to-V) values of the cutting forces show that the static cutting force values are reduced by half when the tool inclination was increased from 0 to 15°. P-to-V cutting force values in along-the-feed direction were also decreased in the inclined machining. DA - 2012/10/25 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bd951fa3-237e-4036-a2b7-64c99956d2c9 ER - TY - JOUR TI - Estimating 3D human shapes from measurements DO - 10.1007/s00138-012-0472-y AU - Wuhrer, Stefanie AU - Shu, Chang T2 - Machine Vision and Applications SN - 0932-8092 SN - 1432-1769 KW - human models KW - statistical prior KW - three-dimensional reconstruction AB - Recent advances in 3D imaging technologies give rise to databases of human shapes, from which statistical shape models can be built. These statistical models represent prior knowledge of the human shape and enable us to solve shape reconstruction problems from partial information. Generating human shape from traditional anthropometric measurements is such a problem, since these 1D measurements encode 3D shape information. Combined with a statistical shape model, these easy-to-obtain measurements can be leveraged to create 3D human shapes. However, existing methods limit the creation of the shapes to the space spanned by the database and thus require a large amount of training data. In this paper, we introduce a technique that extrapolates the statistically inferred shape to fit the measurement data using non-linear optimization. This method ensures that the generated shape is both human-like and satisfies the measurement conditions. We demonstrate the effectiveness of the method and compare it to existing approaches through extensive experiments, using both synthetic data and real human measurements. DA - 2012/12/23 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 64da30f4-912c-47d6-a4e5-dbc8edc2b0a9 ER - TY - JOUR TI - Simple sequence repeat marker development from bacterial artificial chromosome end sequences and expressed sequence tags of flax (Linum usitatissimum L.) DO - 10.1007/s00122-012-1860-4 AU - Cloutier, Sylvie AU - Miranda, Evelyn AU - Ward, Kerry AU - Radovanovic, Natasa AU - Reimer, Elsa AU - Walichnowski, Andrzej AU - Datla, Raju AU - Rowland, Gordon AU - Duguid, Scott AU - Ragupathy, Raja T2 - Theoretical and Applied Genetics SN - 0040-5752 SN - 1432-2242 VL - 125 IS - 4 SP - 685 EP - 694 KW - Association mapping KW - bacterial artificial chromosomes KW - comparative analysis KW - Dinucleotides KW - expressed sequence tags KW - genetic resources KW - genome sizes KW - genomics KW - limun usitatissimum KW - oil seed crops KW - quantitative trait locus KW - simple sequence repeats KW - simple sequence-repeat markers KW - trinucleotides KW - whole-genome shotgun AB - Flax is an important oilseed crop in North America and is mostly grown as a fibre crop in Europe. As a self-pollinated diploid with a small estimated genome size of ~370 Mb, flax is well suited for fast progress in genomics. In the last few years, important genetic resources have been developed for this crop. Here, we describe the assessment and comparative analyses of 1,506 putative simple sequence repeats (SSRs) of which, 1,164 were derived from BAC-end sequences (BESs) and 342 from expressed sequence tags (ESTs). The SSRs were assessed on a panel of 16 flax accessions with 673 (58 %) and 145 (42 %) primer pairs being polymorphic in the BESs and ESTs, respectively. With 818 novel polymorphic SSR primer pairs reported in this study, the repertoire of available SSRs in flax has more than doubled from the combined total of 508 of all previous reports. Among nucleotide motifs, trinucleotides were the most abundant irrespective of the class, but dinucleotides were the most polymorphic. SSR length was also positively correlated with polymorphism. Two dinucleotide (AT/TA and AG/GA) and two trinucleotide (AAT/ATA/TAA and GAA/AGA/AAG) motifs and their iterations, different from those reported in many other crops, accounted for more than half of all the SSRs and were also more polymorphic (63.4 %) than the rest of the markers (42.7 %). This improved resource promises to be useful in genetic, quantitative trait loci (QTL) and association mapping as well as for anchoring the physical/genetic map with the whole genome shotgun reference sequence of flax. DA - 2012/04/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 109b0aa3-22d2-42f5-b079-428851e11109 ER - TY - JOUR TI - Real-time monitoring of influenza virus production kinetics in HEK293 cell cultures DO - 10.1002/btpr.1601 AU - Petiot, Emma AU - Kamen, Amine T2 - Biotechnology Progress VL - 29 IS - 1 SP - 275 EP - 284 KW - influenza; cell culture; in-process monitoring; kinetics; vaccines AB - There is an increased interest from the vaccine industry to use mammalian cell cultures for influenza vaccine manufacturing. Therefore, it became important to study the influenza infection mechanism, the viral–host interaction, and the replication kinetics from a bioprocessing stand point to maximize the influenza viral production yield in cell culture. In the present work, influenza replication kinetics was studied in HEK293 cells. Two infection conditions were evaluated, a low (0.01) and a high multiplicity of infection (1.0). Critical time points of the viral production cycle (infection, protein synthesis, viral assembly and budding, viral release, and host-cell death) were identified in small-scale cell cultures. Additionally, cell growth, viability, and viral titers were monitored in the viral production process. The infection state of the cultivated cell population was assessed by influenza immunolabeling throughout the culture period. Influenza virus production kinetics were also on-line monitored by dielectric spectroscopy and successfully correlated to real-time capacitance measures. Overall, this work provided insights into the mechanisms associated with the infection of human HEK293 cell line by the influenza virus and demonstrated, once again, the usefulness of multifrequency scanning permittivity for in-line monitoring and supervision of cell-based viral production processes. DA - 2012/11/19 PY - 2012 PB - Wiley LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 119f0649-07fc-4898-bb5d-44af3fbf34e8 ER - TY - JOUR TI - A novel polyethyleneimine-coated adeno-associated virus-like particle formulation for efficient siRNA delivery in breast cancer therapy : preparation and in vitro analysis DO - 10.2147/IJN.S26891 AU - Shao, Wei AU - Paul, Arghya AU - Abbasi, Sana AU - Chahal, Parminder S. AU - Mena, Jimmy A. AU - Montes, Johnny AU - Kamen, Amine AU - Prakash, Satya T2 - International Journal of Nanomedicine VL - 7 SP - 1575 EP - 1586 AB - BACKGROUND: Systemic delivery of small interfering RNA (siRNA) is limited by its poor stability and limited cell-penetrating properties. To overcome these limitations, we designed an efficient siRNA delivery system using polyethyleneimine-coated virus-like particles derived from adeno-associated virus type 2 (PEI-AAV2-VLPs). METHODS: AAV2-VLPs were produced in insect cells by infection with a baculovirus vector containing three AAV2 capsid genes. Using this method, we generated well dispersed AAV2-VLPs with an average diameter of 20 nm, similar to that of the wild-type AAV2 capsid. The nanoparticles were subsequently purified by chromatography and three viral capsid proteins were confirmed by Western blot. The negatively charged AAV2-VLPs were surface-coated with PEI to develop cationic nanoparticles, and the formulation was used for efficient siRNA delivery under optimized transfection conditions. RESULTS: PEI-AAV2-VLPs were able to condense siRNA and to protect it from degradation by nucleases, as confirmed by gel electrophoresis. siRNA delivery mediated by PEI-AAV2-VLPs resulted in a high transfection rate in MCF-7 breast cancer cells with no significant cytotoxicity. A cell death assay also confirmed the efficacy and functionality of this novel siRNA formulation towards MCF-7 cancer cells, in which more than 60% of cell death was induced within 72 hours of transfection. CONCLUSION: The present study explores the potential of virus-like particles as a new approach for gene delivery and confirms its potential for breast cancer therapy. DA - 2012/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ab66c997-cbc4-4156-8082-b74816b88740 ER - TY - JOUR TI - Efficacy and site-specificity of adenoviral vector integration mediated by the phage φC31 integrase DO - 10.1089/hgtb.2012.122 AU - Robert, Marc-André AU - Zeng, Yue AU - Raymond, Benoît AU - Desfossé, Laurie AU - Mairey, Emilie AU - Tremblay, Jacques P. AU - Massie, Bernard AU - Gilbert, Rénald T2 - Human Gene Therapy Methods VL - 23 IS - 6 SP - 393 EP - 407 AB - Adenoviral vectors deleted of all their viral genes (helper-dependent [HD]) are efficient gene-transfer vehicles. Because transgene expression is rapidly lost in actively dividing cells, we investigated the feasibility of using phage C31 integrase (C31-Int) to integrate an HD carrying an attB site and the puromycin resistance gene into human cells (HeLa) and murine myoblasts (C2C12) by co-infection with a second HD-expressing C31-Int. Because the HD genome is linear, we also investigated whether its circularization, through expression of Cre using a third HD, affects integration. Efficacy and specificity were determined by scoring the number of puromycin-resistant colonies and by sequencing integration sites. Unexpectedly, circularization of HD was unnecessary and it even reduced the integration efficacy. The maximum integration efficacy achieved was 0.5% in HeLa cells and 0.1% in C2C12 myoblasts. Up to 76% of the integration events occurred at pseudo attP sites and previously characterized hotspots were found. A small (two- to three-fold) increase in the number of γ-H2AX positive foci, accompanied by no noticeable change in γ-H2AX expression, indicated the low genotoxicity of C31-Int. In conclusion, integration of HD mediated by C31-Int is an attractive alternative to engineer cells, because it permits site-specific integration of large DNA fragments with low genotoxicity. DA - 2012/11/29 PY - 2012 PB - Mary Ann Liebert LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fb4df2e7-3184-4989-931c-425c112959fe ER - TY - JOUR TI - A mass spectrometry-based plasma protein panel targeting the tumor microenvironment in patients with breast cancer DO - 10.1016/j.jprot.2012.11.004 AU - Cohen, Alejandro AU - Wang, Edwin AU - Chisholm, Kenneth A. AU - Kostyleva, Ripsik AU - O'Connor-McCourt, Maureen AU - Pinto, Devanand M. T2 - Journal of Proteomics SN - 1874-3919 VL - 81 SP - 135 EP - 147 KW - breast cancer; tumor microenvironment; plasma proteomics; intraprotein variability AB - Proteins secreted or shed by cancerous cells are seen as a rich source of biomarkers and novel therapeutic targets. Recently, the importance of the tumor microenvironment, which comprises the surrounding non-tumor cells, has received increased attention for its role in tumor progression. We developed a targeted proteomics assay to monitor a panel of plasma proteins postulated to be present in the tumor microenvironment. The plasma of 76 breast cancer patients was depleted of abundant circulating proteins, enzymatically digested and labeled by reductive methylation. The labeled digests were analyzed by tandem mass spectrometry using a multiple reaction monitoring acquisition method. The protein targets were correlated with the tumor characteristics, the extent of the disease and the clinical staging of the patients. Linear discriminant analysis revealed that infiltrating ductal and invasive mammary breast carcinomas could be grouped based on distinctive peptide levels of fibronectin, clusterin, gelsolin and α-1-microglobulin/Inter-α-trypsin inhibitor light chain precursor (AMBP). These proteins have been previously associated with breast cancer at the tissue level, however, this is the first study to measure plasma levels of these proteins and correlate these levels with clinical features. Significant variability was seen between unique peptides belonging to the same protein. This article is part of a Special Issue entitled: From protein structures to clinical applications. DA - 2012/11/20 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 923e0e9f-3606-4c8c-9f89-77368d4c69c2 ER - TY - JOUR TI - A versatile coiled-coil tethering system for the oriented display of ligands on nanocarriers for targeted gene delivery DO - 10.1016/j.biomaterials.2012.10.047 AU - Fortier, Charles AU - De Crescenzo, Gregory AU - Durocher, Yves T2 - Biomaterials SN - 0142-9612 VL - 34 IS - 4 SP - 1344 EP - 1353 KW - transfection; polyethylenimine; non-viral vector; targeting; oriented tethering; epidermal growth factor (EGF) AB - Surface modification of non-viral gene delivery nanocarriers may provide advanced features such as receptor targeting, endosomal escape and nuclear import. We here report the design of a versatile and tunable immobilization protocol to functionalize nanocarriers for improved transient gene expression. Our strategy is based on specific interactions occurring between a coil-tagged ligand and a complementary coil-functionalized nanocarrier. As a proof of concept, targeting of DNA/polyethylenimine polyplexes to the epidermal growth factor receptor of A431 cells was investigated. Coiled-coil-mediated oriented tethering of epidermal growth factor triggered a drastic increase of the internalization rate of the targeted polyplexes. To explore the tunability of our platform, surface density of targeting ligand was varied; our results indicated that the internalization rate varied with the ligand-to-polyplex ratio in a “switch mode” fashion. This work prefigures possible avenues for our coiled-coil platform in multiplex functionalization to address transient gene expression bottlenecks in recombinant protein production. DA - 2012/11/06 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1c9e37f0-5368-46c5-8d02-fe1ea701247c ER - TY - JOUR TI - Sulfonation of glycopeptide antibiotics by sulfotransferase StaL depends on conformational flexibility of aglycone scaffold DO - 10.1073/pnas.1205377109 AU - Shi, Rong AU - Munger, Christine AU - Kalan, Lindsay AU - Sulea, Traian AU - Wright, Gerard D. AU - Cygler, Miroslaw T2 - PNAS (Proceedings of the National Academy of Sciences of the United States of America) SN - 1091-6490 VL - 109 IS - 29 SP - 11824 EP - 11829 KW - substrate binding; substrate flexibility; substrate recognition AB - Although glycopeptide antibiotics (GPAs), including vancomycin and teicoplanin, represent the most important class of antiinfective agents in the treatment of serious Gram-positive bacterial infections, their usefulness is threatened by the emergence of resistant strains. GPAs are complex natural products consisting of a heptapeptide skeleton assembled via nonribosomal peptide synthesis and constrained through multiple crosslinks, with diversity resulting from enzymatic modifications by a variety of tailoring enzymes, which can be used to produce GPA analogues that could overcome antibiotic resistance. GPA-modifying sulfotransferases are promising tools for generating the unique derivatives. Despite significant sequence and structural similarities, these sulfotransferases modify distinct side chains on the GPA scaffold. To provide insight into the spatial diversity of modifications, we have determined the crystal structure of the ternary complex of bacterial sulfotransferase StaL with the cofactor product 3′-phosphoadenosine 5′-phosphate and desulfo-A47934 aglycone substrate. Desulfo-A47934 binds with the hydroxyl group on the 4-hydroxyphenylglycine in residue 1 directed toward the 3′-phosphoadenosine 5′-phosphate and hydrogen-bonded to the catalytic His67. Homodimeric StaL can accommodate GPA substrate in only one of the two active sites because of potential steric clashes. Importantly, the aglycone substrate demonstrates a flattened conformation, in contrast to the cup-shaped structures observed previously. Analysis of the conformations of this scaffold showed that despite the apparent rigidity due to crosslinking between the side chains, the aglycone scaffold displays substantial flexibility, important for enzymatic modifications by the GPA-tailoring enzymes. We also discuss the potential of using the current structural information in generating unique GPA derivatives. DA - 2012/07 PY - 2012 PB - National Academy of Science LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 49c90450-1d77-4423-98ab-fb18aadc2447 ER - TY - JOUR TI - Seeking antifungal drug synergies AU - Whiteway, Malcolm T2 - Microbe Magazine VL - 7 IS - 5 SP - 233 EP - 237 DA - 2012/05 PY - 2012 PB - American Society of Microbiology LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e112d83b-99a6-417e-84ba-bdf789cff64e ER - TY - JOUR TI - Molecular targeting of CEACAM6 using antibody probes of different sizes DO - 10.1016/j.jconrel.2012.04.043 AU - Niu, Gang AU - Murad, Yanal M. AU - Gao, Haokao AU - Hu, Shuo AU - Guo, Ning AU - Jacobson, Orit AU - Nguyen, Thanh-Dung AU - Zhang, Jianbing AU - Chen, Xiaoyuan T2 - Journal of Controlled Release VL - 161 IS - 1 SP - 18 EP - 24 KW - CEACAM6; pancreatic cancer; heavy chain antibody; 64Cu; positron emission tomography (PET) AB - Carcinocinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is overexpressed in a number of human malignancies, especially in pancreatic cancer. It has been demonstrated that CEACAM6 is a potential target for monoclonal antibody (mAb) therapy with a safe therapeutic index. Here, we labeled three anti-CEACAM6 antibodies of different sizes, including a single-domain antibody 2A3 (16 kDa), a heavy chain antibody 2A3-mFc (80 kDa) and a full length antibody 9A6 (150 kDa), with 64Cu to image CEACAM6 expression in a xenografted pancreatic tumor model. For positron emission tomography (PET) imaging, the tumor mice were intravenously injected with 64Cu-DOTA-antibodies and static scans were obtained at 5 min, 0.5, 1, 2, 4, 8 and 24 h post-injection (p.i.). All three antibodies showed strong CEACAM6 binding. Ex vivo immunostaining on tumor sections at 24 h after Ab injection demonstrated specific tumor targeting of both 2A3-mFc and 9A6. 64Cu-DOTA-2A3 showed fast BxPC3 tumor uptake and rapid whole-body clearance. At 24 h p.i., the tumor uptakes were 98.2 ± 6.12%ID/g for 64Cu-DOTA-2A3-mFc and 57.8 ± 3.73%ID/g for 64Cu-DOTA-9A6, respectively. Compared with the full length antibody 9A6, the heavy chain antibody 2A3-mFc showed higher tumor uptake, lower liver uptake and shorter circulation half-life. All the data supported that the heavy chain antibody 2A3-mFc is superior to the single domain antibody and the full-length antibody with regard to tumor detection and pharmacokinetics, which has great potential to be developed for CEACAM6-targeted pancreatic cancer imaging and therapy. DA - 2012/05/05 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a8516045-e8d1-4a05-b611-43c7773487af ER - TY - JOUR TI - Alloy solid solution strengthening of Mg alloys: valence effect DO - 10.1002/pssb.201248195 AU - Chen, Kuiying AU - Boyle, Kevin P. T2 - physica status solidi (b) SN - 03701972 VL - 249 IS - 11 SP - 2089 EP - 2095 KW - density functional theory KW - Mg alloys KW - solid solutions AB - Ab initio density functional theory (DFT) calculations were carried out to investigate alloy solid solution strengthening of hexagonal close packed (HCP) Mg. The binary solid solution Mg–X base alloys (X = Gd, Nd, Ce, Bi, In, and Sn) were examined to identify a possible valence effect on the solution strengthening in terms of electronic density of states (DOS) and electron localized function (ELF). An addition of rare earth (RE) elements Gd, Nd, and Ce in Mg results in a hybridization between the localized f electrons of RE elements and the p electrons of Mg. The hybridization is primarily responsible for the formation of covalent bonds between RE elements and Mg. This electronic structure was then validated by the calculated ELF, illustrating a distribution of localized electrons between Mg and RE atoms. This peculiar chemical bonding characteristic successfully explains the experimentally observed solid solution strengthening induced by Gd, Nd, and Ce additions. An addition of sp-elements of Bi, In, and Sn in Mg, however, leads to the formation of typical ionic bonds, which are not capable of inducing solid solution strengthening in Mg alloys. A discussion was made on a possible relationship between the chemical bonds and solid solution strengthening in Mg alloys. DA - 2012/08/17 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : abc7b855-8a32-4c3c-a6e1-750e4ceb7b80 ER - TY - JOUR TI - Targeted glycomics by selected reaction monitoring for highly sensitive glycan compositional analysis DO - 10.1002/pmic.201100567 AU - Zhang, Hongquan AU - Wang, Zhaohui AU - Stupak, Jacek AU - Ghribi, Othman AU - Geiger, Jonathan D. AU - Liu, Qing Yan AU - Li, Jianjun T2 - Proteomics SN - 16159853 VL - 12 IS - 15-16 SP - 2510 EP - 2522 KW - Carbohydrate KW - Glycoproteomics KW - Glycosylation KW - LC-SRM KW - N-Glycan KW - Quantitative glycomics AB - The development of glycomics increasingly requires the detection and quantification of large numbers of glycans, which is only partially achieved by current glycomics approaches. Taking advantage of selected reaction monitoring to enhance both sensitivity and selectivity, we report here a strategy termed targeted glycomics that enables highly sensitive and consistent identification and quantification of diverse glycans across multiple samples at the same time. In this proof-of-principle study, we validated the method by analyzing global N-glycans expressed in different systems: single proteins, cancer cells, and serum samples. A dynamic range of three orders of magnitude was obtained for the detection of all five glycans released from ribonuclease B. The limit of detection of 80 attomole for Man9GlcNAc2 demonstrated the excellent sensitivity of the method. The capability of the strategy to identify diverse glycans was demonstrated by identification and detection of 162 different glycans and isomers from pancreatic cancer cells. The sensitivity of the method was illustrated further by the ability to detect eight glycans from 250 cancer cells and five glycans released from 100 cancer cells. In serum obtained from rabbits fed control diet or diet enriched with 2% cholesterol, differences to 42 glycans were accurately measured and this indicates that this strategy might find use in studies of biomarker discovery and validation. DA - 2012/07/23 PY - 2012 LA - eng N1 - The authors affiliated with NRC were with the NRC Institute for Biological Sciences prior to April 1, 2012. C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ee4d1fa2-6367-4c8f-89c1-d44c07ffeab5 ER - TY - JOUR TI - Protein–ligand binding free energies from exhaustive docking DO - 10.1021/jp212646s AU - Purisima, Enrico O. AU - Hogues, Hervé T2 - The Journal of Physical Chemistry B VL - 116 IS - 23 SP - 6872 EP - 6879 KW - protein-ligand binding; Monte Carlo and colecular dynamics simulations; elctrostatic models AB - We explore the use of exhaustive docking as an alternative to Monte Carlo and molecular dynamics sampling for the direct integration of the partition function for protein–ligand binding. We enumerate feasible poses for the ligand and calculate the Boltzmann factor contribution of each pose to the partition function. From the partition function, the free energy, enthalpy, and entropy can be derived. All our calculations are done with a continuum solvation model that includes solving the Poisson equation. In contrast to Monte Carlo and molecular dynamics simulations, exhaustive docking avoids (within the limitations of a discrete sampling) the question of “Have we run long enough?” due to its deterministic complete enumeration of states. We tested the method on the T4 lysozyme L99A mutant, which has a nonpolar cavity that can accommodate a number of small molecules. We tested two electrostatic models. Model 1 used a solute dielectric of 2.25 for the complex apoprotein and free ligand and 78.5 for the solvent. Model 2 used a solute dielectric of 2.25 for the complex and apoprotein but 1.0 for the free ligand. For our test set of eight molecules, we obtain a reasonable correlation with a Pearson r2 = 0.66 using model 1. The trend in binding affinity ranking is generally preserved with a Kendall τ = 0.64 and Spearman ρ = 0.83. With model 2, the correlation is improved with a Pearson r2 = 0.83, Kendall τ = 0.93, and Spearman ρ = 0.98. This suggests that the energy function and sampling method adequately captured most of the thermodynamics of binding of the nonpolar ligands to T4 lysozyme L99A. DA - 2012/03/20 PY - 2012 PB - ACS Publications LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 92d20f58-ed85-460b-974d-eb2e4d929a1e ER - TY - JOUR TI - Structure and morphology of new bio-based thermoplastic polyurethanes obtained from dimeric fatty acids DO - 10.1002/mame.201100278 AU - Bueno-Ferrer, Carmen AU - Hablot, Elodie AU - Perrin-Sarazin, Florence AU - Garrigós, M. Carmen AU - Jiménez, Alfonso AU - Averous, Luc T2 - Macromolecular Materials and Engineering SN - 14387492 VL - 297 IS - 8 SP - 777 EP - 784 KW - atomic force microscopy KW - bio-based polyols KW - dimeric fatty acids KW - polyurethanes KW - structure-property relationships AB - Bio-based TPUs from dimer acid-based polyols are synthesised by using a two-step prepolymer process including reactive processing. The effect of the polyol on the final chemical structures, morphologies and properties of bio-based TPUs is evaluated by different analytical techniques. It is observed that the percentage of hard segment (HS) distributed in organised and unorganised phases is a key factor to control the materials properties. DSC reveals that the percentages of HS dispersed in the soft domains are high at low experimental HS contents. Multiscale microscopies show better defined organised structures with increasing HS content in TPUs, highlighting the importance of the distribution between hard and soft segments in the material structure. DA - 2012/02/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f0747b84-2924-4b49-8653-8f668be3c4fc ER - TY - JOUR TI - Involvement of NOS3 in RA-induced neural differentiation of human NT2/D1 cells DO - 10.1002/jnr.23118 AU - Jezierski, Anna AU - Deb-Rinker, Paromita AU - Sodja, Caroline AU - Walker, P. Roy AU - Ly, Dao AU - Haukenfrers, Julie AU - Sandhu, Jagdeep K. AU - Bani-Yaghoub, Mahmud AU - Sikorska, Marianna T2 - Journal of Neuroscience Research SN - 03604012 VL - 90 IS - 12 SP - 2362 EP - 2377 KW - endothelial nitric oxide synthase KW - nuclear localization KW - cell cycle exit KW - neurogenesis KW - chromatin remodeling KW - epigenetic regulation AB - Nitric oxide (NO) plays a key role in neurogenesis as a regulator of cell proliferation and differentiation. NO is synthesized from the amino acid L-arginine by nitric oxide synthases (NOS1, NOS2, and NOS3), which are encoded by separate genes and display different tissue distributions. We used an in vitro model of RA-induced neural differentiation of NT2 cells to examine which of the three NO-synthesizing enzymes is involved in this process. The results revealed a transient induction of NOS3 (known as the constitutively expressed endothelial nitric oxide synthase; eNOS) during the time course of the RA treatment. The peak of gene expression and the nuclear presence of NOS3 protein coincided with cell cycle exit of NT2-derived neuronal precursors. The subsequent analysis of cytosine methylation and histone H3 acetylation of the human NOS3 5′ regulatory sequences indicated that epigenetic modifications, especially upstream of the proximal promoter (−734 to −989, relative to exon 2 TSS at +1), were also taking place. NOS1 was expressed only in the differentiated neurons (NT2-N), whereas NOS2 was not expressed at all in this cellular model. Thus, a burst of NO production, possibly required to inhibit neural cell proliferation, was generated by the transient expression of NOS3. This pattern of gene expression, in turn, required epigenetic remodeling of its regulatory region. DA - 2012/09/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 68038c63-4004-421c-8621-60e804123b4b ER - TY - JOUR TI - Strength and muscle specificity of a compact promoter derived from the slow troponin I gene in the context of episomal (gutless adenovirus) and integrating (lentiviral) vectors DO - 10.1002/jgm.2675 AU - Robert, Marc-André AU - Lin, Yuanbang AU - Bendjelloul, Mehdi AU - Zeng, Yue AU - Dessolin, Sofien AU - Broussau, Sophie AU - Larochelle, Nancy AU - Nalbantoglu, Josephine AU - Massie, Bernard AU - Gilbert, Rénald T2 - The Journal of Gene Medicine SN - 1099-498X VL - 14 IS - 12 SP - 746 EP - 760 KW - gutless adenovirus KW - helper-dependent adenovirus KW - lentivirus KW - muscle KW - muscular dystrophy KW - promoter AB - Background:Gutless adenovirus (helper-dependent adenoviral vector; HDAd) and lentiviral vectors (LV) are attractive vectors for the gene therapy of muscle diseases. Because the organization of their DNA (episomal versus integrated) differs, we investigated whether the strength and specificity of ΔUSEx3, a novel muscle-specific promoter previously tested with plasmid, were maintained in the context of these vectors. Methods: Two HDAds expressing β-galactosidase regulated by ΔUSEx3 or CAG [cytomegalovirus (CMV) enhancer/β-actin promoter], and three LV expressing green fluorescent protein regulated by ΔUSEx3, CMV or a modified skeletal α-actin promoter (SPcΔ5-12), were constructed. Gene expression was compared in cell culture and after intravenous (HDAd only) and intramuscular injection of mice. Results: Irrespective of the vector used, ΔUSEx3 remained poorly active in nonmuscle cells and tissues. In myotubes, ΔUSEx3 was as strong as CMV and SPcΔ5-12, although it was ten-fold weaker than CAG, a proven powerful promoter in muscle. In cell culture, ΔUSEx3 activity in the context of LV was more stable than CMV, indicating it is less prone to silencing. In the context of HDAd, the behavior of ΔUSEx3 in skeletal muscle mirrored that of cell culture (10% of the CAG activity and half the number of transduced fibers). Surprisingly, in muscles treated with LV, ΔUSEx3 activity was five-fold lower than SPcΔ5-12. Conclusions: The data obtained in the present study confirm that ΔUSEx3 is a strong and robust muscle-specific promoter in the context of HDAd (cell culture and in vivo) and LV (cell culture). However, it was less efficient in vivo in the context of LV. DA - 2012/12/21 PY - 2012 PB - Wiley LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c6724687-77f0-4767-a34e-0fe3200cb6cd ER - TY - JOUR TI - Efficient treatment of solvation shells in 3D molecular theory of solvation DO - 10.1002/jcc.22974 AU - Gusarov, Sergey AU - Pujari, Bhalchandra S. AU - Kovalenko, Andriy T2 - Journal of Computational Chemistry SN - 01928651 VL - 33 IS - 17 SP - 1478 EP - 1494 KW - solvation structure and thermodynamics KW - 3D-RISM molecular theory of solvation KW - MDIIS method of solving integral equations KW - core–shell-asymptotics technique KW - memory reduction AB - We developed a technique to decrease memory requirements when solving the integral equations of three-dimensional (3D) molecular theory of solvation, a.k.a. 3D reference interaction site model (3D-RISM), using the modified direct inversion in the iterative subspace (MDIIS) numerical method of generalized minimal residual type. The latter provides robust convergence, in particular, for charged systems and electrolyte solutions with strong associative effects for which damped iterations do not converge. The MDIIS solver (typically, with 2 × 10 iterative vectors of argument and residual for fast convergence) treats the solute excluded volume (core), while handling the solvation shells in the 3D box with two vectors coupled with MDIIS iteratively and incorporating the electrostatic asymptotics outside the box analytically. For solvated systems from small to large macromolecules and solid–liquid interfaces, this results in 6- to 16-fold memory reduction and corresponding CPU load decrease in MDIIS. We illustrated the new technique on solvated systems of chemical and biomolecular relevance with different dimensionality, both in ambient water and aqueous electrolyte solution, by solving the 3D-RISM equations with the Kovalenko–Hirata (KH) closure, and the hypernetted chain (HNC) closure where convergent. This core–shell-asymptotics technique coupling MDIIS for the excluded volume core with iteration of the solvation shells converges as efficiently as MDIIS for the whole 3D box and yields the solvation structure and thermodynamics without loss of accuracy. Although being of benefit for solutes of any size, this memory reduction becomes critical in 3D-RISM calculations for large solvated systems, such as macromolecules in solution with ions, ligands, and other cofactors. DA - 2012/04/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 17a61ff9-9919-4b97-80f5-99ee024528c7 ER - TY - JOUR TI - In vitro biocompatibility assessment of functionalized magnetite nanoparticles: biological and cytotoxicological effects DO - 10.1002/jbm.a.34096 AU - Mbeh, D. A. AU - França, R. AU - Merhi, Y. AU - Zhang, X. F. AU - Veres, T. AU - Sacher, E. AU - Yahia, L. T2 - Journal of Biomedical Materials Research Part A SN - 15493296 VL - 100A IS - 6 SP - 1637 EP - 1646 KW - biocompatibility KW - cell viability KW - cytotoxicological effects KW - functionalized magnetite nanoparticles AB - In the biomedical field, nanomaterials have the potential for use in the targeted delivery of drugs in the human body and in the diagnosis and therapy of certain diseases. In the category of targeted delivery, magnetite (Fe3O4) nanoparticles have received much attention. As with any similar new therapy, when such nanoparticles are functionalized with chemical groups designed to permit the specific attachment of drugs, cytotoxicological testing is necessary before moving to animal models. Here, we consider several variously functionalized magnetite nanoparticles, including those prepared with (1) a monolayer of oleic acid (Fe3O4@OA), which is subsequently converted to (2) a shell of amine-containing silane (Fe3O4@NH2), (3) a shell of silica (Fe3O4@SiO2), and (4) a shell of amine-containing silane over a shell of silica (Fe3O4@SiO2@NH2). These latter three functionalities were evaluated for biocompatibility, cellular morphology, mitochondrial function (MTT assay), lactate dehydrogenase membrane leakage (LDH assay), and proinflammatory potential through enzyme linked immunosorbent assay (ELISA) for interleukin 6 (IL-6). Controlled tests were performed over a period of 72 h, with results showing LDH leakage and abnormal Il-6 secretion at high concentrations (>50 μg/mL). The tests showed that, in addition to the surface characteristics of the nanoparticles, both the nutrient medium and the time of suspension before exposure to cells also contribute to nanoparticle cytotoxicity. DA - 2012/03/23 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2c697146-bb74-473c-b495-b61b10a96b9f ER - TY - JOUR TI - Real-time diagnosing polymer processing in injection molding using ultrasound DO - 10.1002/app.36868 AU - Zhao, Lijuan AU - Lai, Yu AU - Pei, Chen AU - Jen, Cheng-Kui AU - Wu, Kuo-Ding T2 - Journal of Applied Polymer Science SN - 0021-8995 VL - 126 IS - 6 SP - 2059 EP - 2066 KW - ultrasound; real-time; injection molding; processing; polymer storage modulus AB - Ultrasonic diagnosing technique with a new high-temperature ultrasonic transducer is developed to real-time diagnose polymer processing and its morphology changes in injection molding processing. Compared with the previous researches, the new technique can provide more and accurate information. In this study, ultrasound diagnosis shows that longitudinal wave can real-time characterize the data of the injection process and polymer morphology changes, including melt flow arrival time, the part ejection time, filling and packing stages, polymer solidification process, and the morphology changes during polymer crystallization. Shear waves can real-time diagnose Young's and shear storage modulus, anisotropy property of polymer in injection molding. During our research, real-time ultrasonic diagnosis shows that the storage modulus along the vertical direction is larger than that of the parallel to the melt flow direction under our setup injection conditions. Scanning electron microscopy and dynamic mechanical analysis measurements present that it is because the crystalline lamellas of HDPE are parallel arrangement and grow in a vertical to melt flow direction owing to injection shear force under a certain injection conditions. DA - 2012/12/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f42adf07-3100-4287-830a-cf11408b348d ER - TY - JOUR TI - Preparation and properties of extruded thermoplastic starch/polymer blends DO - 10.1002/app.36724 AU - Huneault, Michel A. AU - Li, Hongbo T2 - Journal of Applied Polymer Science SN - 00218995 VL - 126 IS - S1 SP - E96 EP - E108 KW - thermoplastic starch; polymer blends; polysaccharides; renewable resources; plastics AB - This article examines the starch gelatinization and the blend morphology development in blends of thermoplastic starch (TPS) with high-density polyethylene, polypropylene, polystyrene, poly(lactic acid), and polycaprolactone. The TPS gelatinization and mixing with the second polymer was carried out on a twin-screw extrusion process, where the starch was sequentially gelatinized, devolatilized, and then mixed in the molten state with a synthetic polymer. The role of excess water and process temperature on starch gelatinization was assessed by measuring the X-ray scattering. All prepared blends included 25 % TPS that was dispersed in the synthetic polymer matrix. Compatibilized versions of these same blends were obtained by partially substituting the polymer matrices with maleated analogs. The blend morphology was probed by scanning electron microscopy. Complete starch gelatinization was obtained when the gelatinization process was carried out over 100°C regardless of amount of water used as co-plasticizer. The blend morphologies were greatly improved when a maleated compatibilizer was added. Only TPS/PCL blends exhibited a finely dispersed TPS phase without the use of a compatibilizer. In general, the addition of the TPS reduced slightly the tensile modulus and strength of the different polymers and more importantly the elongation at break. DA - 2012/03/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e5bc9f77-4045-4a85-9090-920e0e78a041 ER - TY - JOUR TI - Recognition of sialylated poly-N-acetyllactosamine chains on N- and O-linked glycans by human and avian influenza A virus hemagglutinins DO - 10.1002/anie.201200596 AU - Nycholat, Corwin M. AU - Mcbride, Ryan AU - Ekiert, Damian C. AU - Xu, Rui AU - Rangarajan, Janani AU - Peng, Wenjie AU - Razi, Nahid AU - Gilbert, Michel AU - Wakarchuk, Warren AU - Wilson, Ian A. AU - Paulson, James C. T2 - Angewandte Chemie International Edition SN - 1433-7851 VL - 51 IS - 20 SP - 4860 EP - 4863 KW - glycans; hemagglutinins; influenza viruses; microarrays; sialic acids AB - Human influenza viruses are proposed to recognize sialic acids (pink diamonds) on glycans extended with poly-LacNAc chains (LacNAc=(yellow circle+blue square)). N- and O-linked glycans were extended with different poly-LacNAc chains with α2-3- and α2-6-linked sialic acids recognized by human and avian influenza viruses, respectively. The specificity of recombinant hemagglutinins (receptors in green) was investigated by using glycan microarray technology. DA - 2012/04/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 870ce9ae-23a5-4616-b4be-8b2979e11e7e ER - TY - JOUR TI - Exploring the essential collective dynamics of interacting proteins: application to prion protein dimers DO - 10.1002/prot.24082 AU - Issack, Bilkiss B. AU - Berjanskii, Mark AU - Wishart, David S. AU - Stepanova, Maria T2 - Proteins: Structure, Function, and Bioinformatics SN - 08873585 VL - 80 IS - 7 SP - 1847 EP - 1865 KW - protein–protein interactions KW - flexibility KW - dynamic domains KW - correlated motions KW - binding free energy KW - molecular dynamics simulation KW - prion aggregation AB - Essential collective dynamics is a promising and robust approach for analysing the slow motions of macromolecules from short molecular dynamics trajectories. In this study, an extension of the method to treat a collection of interacting protein molecules is presented. The extension is applied to investigate the effects of dimerization on the collective dynamics of ovine prion protein molecules in two different arrangements. Examination of the structural plasticity shows that aggregation has a restricting effect on the local mobility of the prion protein molecules in the interfacial regions. Domain motions of the two dimeric ovine prion protein conformations are distinctly different and can be related to interatomic correlations at the interface. Correlated motions are among the slow collective modes extensively analysed by considering both main-chain and side-chain atoms. Correlation maps reveal the existence of a vast network of dynamically correlated side groups, which extends beyond individual subunits via interfacial interconnections. The network is formed by a core of hydrophobic side chains surrounded by hydrophilic groups at the periphery. The relevance of these findings are discussed in the context of mutations associated with prion diseases. The binding free energy of the dimeric conformations is evaluated to probe their thermodynamic stability. The descriptions afforded by the analysis of the essential collective dynamics of the prion dimers are consistent with their binding free energies. The agreement validates the extension of the methodology and provides a means of interpreting the collective dynamics in terms of the thermodynamic stability of ovine prion proteins. DA - 2012/05/10 PY - 2012 LA - eng N1 - Erratum published in Volume 80, Issue 9, page 2330, August 2012. Erratum DOI: 10.1002/prot.24139 C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ac6c61fe-0089-4aa1-aba0-96d9f7a1b72f ER - TY - JOUR TI - Mach, the universe, and foundations of mechanics DO - 10.1002/andp.201100305 AU - Mashhoon, B. AU - Wesson, P. S. T2 - Annalen der Physik SN - 0003-3804 VL - 524 IS - 2 SP - A44 DA - 2012/01/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : aa31ab3e-3560-4034-8077-abdb643e9bb6 ER - TY - JOUR TI - Work function control of interfacial buffer layers for efficient and air-stable inverted low-bandgap organic photovoltaics DO - 10.1002/aenm.201100714 AU - Worfolk, Brian J. AU - Hauger, Tate C. AU - Harris, Kenneth D. AU - Rider, David A. AU - Fordyce, Jordan A. M. AU - Beaupré, Serge AU - Leclerc, Mario AU - Buriak, Jillian M. T2 - Advanced Energy Materials SN - 1614-6832 VL - 2 IS - 3 SP - 361 EP - 368 KW - air stable; cathodic interfacial buffer layers; low bandgap polymers; organic photovoltaics; work functions AB - A water-soluble cationic polythiophene derivative, poly[3-(6-{4-tert-butylpyridiniumyl}-hexyl)thiophene-2,5-diyl] [P3(TBP)HT], is combined with anionic poly(3,4-ethylenedioxythiophene):poly(p-styrenesulfonate) (PEDOT:PSS) on indium tin oxide (ITO) substrates via electrostatic layer-by-layer (eLbL) assembly. By varying the number of eLbL layers, the electrode's work function is precisely controlled from 4.6 to 3.8 eV. These polymeric coatings are used as cathodic interfacial modifiers for inverted-mode organic photovoltaics that incorporate a photoactive layer composed of either poly[(3-hexylthiophene)-2,5-diyl] (P3HT) and the fullerene acceptor [6,6-phenyl-C61-butyric acid methyl ester (PC61BM) or the low bandgap polymer [poly({4,8-di(2-ethylhexyloxyl)benzo[1,2-b:4,5-b′]dithiophene}-2,6-diyl)-alt-({5-octylthieno[3,4-c]pyrrole-4,6-dione}-1,3-diyl) (PBDTTPD)] and the electron acceptor [6,6-phenyl-C71-butyric acid methyl ester (PC71BM)]. The power conversion efficiency (PCE) of the resulting photovoltaic device is dependent on the composition of the eLbL-assembled interface and permits the fabrication of devices with efficiencies of 3.8% and 5.6% for P3HT and PBDTTPD donor polymers, respectively. Notably, these devices demonstrate significant stability with a P3HT:PC61BM system maintaining 83% of its original PCE after 1 year of storage and a PBDTTPD:PC71BM system maintaining 97% of its original PCE after over 1000 h of storage in air, according to the ISOS-D-1 shelf protocol. DA - 2012/01/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 27b5381e-20c2-498d-ad27-732d86b80e8d ER - TY - JOUR TI - Carbonized chicken eggshell membranes with 3D architectures as high-performance electrode materials for supercapacitors DO - 10.1002/aenm.201100548 AU - Li, Zhi AU - Zhang, Li AU - Shalchi Amirkhiz, Babak AU - Tan, Xuehai AU - Xu, Zhanwei AU - Wang, Huanlei AU - Olsen, Brian C. AU - Holt, Chris M. B. AU - Mitlin, David T2 - Advanced Energy Materials SN - 1614-6832 VL - 2 IS - 4 SP - 431 EP - 437 KW - nitrogen-rich carbon; supercapacitors; eggshells; biomass waste; energy storage AB - Supercapacitor electrode materials are synthesized by carbonizing a common livestock biowaste in the form of chicken eggshell membranes. The carbonized eggshell membrane (CESM) is a three-dimensional macroporous carbon film composed of interwoven connected carbon fibers containing around 10 wt% oxygen and 8 wt% nitrogen. Despite a relatively low surface area of 221 m2 g−1, exceptional specific capacitances of 297 F g−1 and 284 F g−1 are achieved in basic and acidic electrolytes, respectively, in a 3-electrode system. Furthermore, the electrodes demonstrate excellent cycling stability: only 3% capacitance fading is observed after 10 000 cycles at a current density of 4 A g−1. These very attractive electrochemical properties are discussed in the context of the unique structure and chemistry of the material. DA - 2012/03/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 931f3382-2c2d-4afd-a32b-8d3ba975f070 ER - TY - JOUR TI - CdSe magic-sized nuclei, magic-sized nanoclusters and regular nanocrystals : monomer effects on nucleation and growth DO - 10.1002/adma.201104081 AU - Yu, Kui T2 - Advanced Materials SN - 0935-9648 VL - 24 IS - 8 SP - 1123 EP - 1132 AB - Colloidal semiconductor quantum dots (QDs) have been well appreciated for their potential in nanophotonics with an unprecedented impact in various areas, including light emitting diodes (LEDs) and solar cells. There is an outstanding demand on the control of size and size distribution for the various applications, with rational design supported by fundamental understanding of nucleation and growth. This Research News introduces recent advances in the synthesis of colloidal CdSe magic-sized nuclei (MSN) exhibiting sharp bandgap emission, with a model proposed to illustrate the nature of monomers and their degree of supersaturation (DS) affecting the formation of various CdSe MSN, magic-sized nanoclusters (MSCs), and regular nanocrystals (RNCs). Also, this model addresses tuning the CdSe RNCs into the CdSe MSN with the presence of cadmium acetate (Cd(OAc)2) affecting the nature of the monomers. DA - 2012/01/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 495523f4-59f1-4501-835f-cd79e63bf9ea ER - TY - JOUR TI - Effects of the molecular weight and the side-chain length on the photovoltaic performance of dithienosilole/thienopyrrolodione copolymers DO - 10.1002/adfm.201102623 AU - Chu, Ta-Ya AU - Lu, Jianping AU - Beaupré, Serge AU - Zhang, Yanguang AU - Pouliot, Jean-Rémi AU - Zhou, Jiayun AU - Najari, Ahmed AU - Leclerc, Mario AU - Tao, Ye T2 - Advanced Functional Materials SN - 1616301X VL - 22 IS - 11 SP - 2345 EP - 2351 KW - photovoltaic devices KW - solar cells KW - fullerenes KW - polymeric materials AB - A series of low-bandgap alternating copolymers of dithienosilole and thienopyrrolodione (PDTSTPDs) are prepared to investigate the effects of the polymer molecular weight and the alkyl chain length of the thienopyrrole-4,6-dione (TPD) unit on the photovoltaic performance. High-molecular-weight PDTSTPD leads to a higher hole mobility, lower device series resistance, a larger fill factor, and a higher photocurrent in PDTSTPD:[6,6]-phenyl C71 butyric acid methyl ester (PC71BM) bulk-heterojunction solar cells. Different side-chain lengths show a significant impact on the interchain packing between polymers and affect the blend film morphology due to different solubilities. A high power conversion efficiency of 7.5% is achieved for a solar cell with a 1.0 cm2 active area, along with a maximum external quantum efficiency (EQE) of 63% in the red region. DA - 2012/03/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bfa82247-3f49-4bc2-a974-03430fb72c9e ER - TY - JOUR TI - Process planning for Floor machining of 2½D pockets based on a morphed spiral tool path pattern DO - 10.1016/j.cie.2012.06.008 AU - Banerjee, Avisekh AU - Feng, Hsi-Yung AU - Bordatchev, Evgueni V. T2 - Computers & Industrial Engineering SN - 03608352 VL - 63 IS - 4 SP - 971 EP - 979 AB - This work proposes a process planning for machining of a Floor which is the most prominent elemental machining feature in a 2½D pocket. Traditionally, the process planning of 2½D pocket machining is posed as stand-alone problem involving either tool selection, tool path generation or machining parameter selection, resulting in sub-optimal plans. For this reason, the tool path generation and feed selection is proposed to be integrated with an objective of minimizing machining time under realistic cutting force constraints for given pocket geometry and cutting tool. A morphed spiral tool path consisting of G1 continuous biarc and arc spline is proposed as a possible tool path generation strategy with the capability of handling islands in pocket geometry. Proposed tool path enables a constant feed rate and consistent cutting force during machining in typical commercial CNC machine tool. The constant feed selection is based on the tool path and cutting tool geometries as well as dynamic characteristics of mechanical structure of the machine tool to ensure optimal machining performance. The proposed tool path strategy is compared with those generated by commercial CAM software. The calculated tool path length and measured dry machining time show considerable advantage of the proposed tool path. For optimal machining parameter selection, the feed per tooth is iteratively optimized with a pre-calibrated cutting force model, under a cutting force constraint to avoid tool rupture. The optimization result shows around 32% and 40% potential improvement in productivity with one and two feed rate strategies respectively. DA - 2012/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b5b02c8f-3e79-4d62-8450-e2d8a57026df ER - TY - JOUR TI - Synthetic diversification of natural products : semi-synthesis and evaluation of triazole jadomycins DO - 10.1039/c2sc00663d AU - Dupuis, Stephanie N. AU - Robertson, Andrew W. AU - Veinot, Thomas AU - Monro, Susan M. A. AU - Douglas, Susan E. AU - Syvitski, Ray T. AU - Goralski, Kerry B. AU - McFarland, Sherri A. AU - Jakeman, David L. T2 - Chemical Science VL - 3 IS - 5 SP - 1640 EP - 1644 AB - Growth of Streptomyces venezuelae ISP5230 with O-propargyl-L-serine led to the efficient production of an alkyne-containing jadomycin. The installed alkyne functionality provided a uniquely reactive handle within the natural product and was subsequently reacted with a series of azides to afford an eight-member library of jadomycin triazoles. The compounds were evaluated for their DNA cleavage, antibacterial and cytotoxic properties. DA - 2012/05/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7c8ec638-71b5-4e4b-ab9f-182f8b017c28 ER - TY - JOUR TI - Convenient contrast enhancement by a hole-free phase plate DO - 10.1016/j.ultramic.2012.02.004 AU - Malac, Marek AU - Beleggia, Marco AU - Kawasaki, Masahiro AU - Li, Peng AU - Egerton, Ray F. T2 - Ultramicroscopy SN - 0304-3991 VL - 118 SP - 77 EP - 89 KW - phase plate; transmission electron microscope; contrast transfer function; charging; low dose TEM; radiation damage; contrast improvement; electron beam induced charging; Zernike phase plate; electron beam induced contamination; cryo TEM AB - Decrease of the irradiation dose needed to obtain a desired signal-to-noise ratio can be achieved by Zernike phase-plate imaging. Here we present results on a hole-free phase plate (HFPP) design that uses the incident electron beam to define the center of the plate, thereby eliminating the need for high precision alignment and with advantages in terms of ease of fabrication. The Zernike-like phase shift is provided by a charge distribution induced by the primary beam, rather than by a hole in the film. Compared to bright-field Fresnel-mode imaging, the hole-free phase plate (HFPP) results in two- to four-fold increase in contrast, leading to a corresponding decrease in the irradiation dose required to obtain a desired signal-to-noise ratio. A local potential distribution, developed due to electron beam-induced secondary-electron emission, is the most likely mechanism responsible for the contrast-transfer properties of the HFPP. DA - 2012/03/05 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2b75d6ee-da07-47d3-99fd-7d2eb7d0db60 ER - TY - JOUR TI - Preferential face deposition of gold nanoparticles on silicon nanowires by galvanic displacement DO - 10.1039/C2CE25254F AU - Sayed, Sayed Youssef AU - Wang, Feng AU - Malac, Marek AU - Li, Peng AU - Wang, Dong AU - Buriak, Jillian T2 - CrystEngComm IS - 16 SP - 5230 EP - 5234 AB - We report the preferential growth of gold nanoparticles on certain crystallographic facets of Si nanowires (NWs). Our synthetic approach uses galvanic displacement, an electroless deposition method; Si NWs act as the source of electrons required for the reduction of gold ions to metallic gold nanoparticles. Si NWs grown along the <112> growth direction have a characteristic rectangular cross-section with two each of (111) and (110) facets. Through detailed transmission electron microscopy (TEM) and TEM tomography, we were able to show the selective growth of gold nanoparticles on the Si(110) facets of the Si NWs with <112> growth directions; gold deposition was not observed on the Si(111) facets. These results may be related to the high reactivity of Si(110) facets towards gold deposition via galvanic displacement as compared to the reactivity of Si(111) facets. DA - 2012/05/11 PY - 2012 PB - RSC Publishing LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : faeb6f91-a756-4dc1-955f-b73039066d2b ER - TY - JOUR TI - Grafting of lignin onto nanostructured silica SBA-15 : preparation and characterization DO - 10.1007/s10934-012-9592-z AU - Saad, Rabih AU - Hawari, Jalal T2 - Journal of Porous Materials VL - 20 IS - 1 SP - 227 EP - 233 KW - Lignin KW - nanostructured silica SBA-15 KW - grafting KW - characterization AB - The slow decline in oil reserves with mounting oil prices is pushing industry to find more sustainable sources for industrial manufacturing. Lignin is the second most abundant natural renewable biopolymer that is underutilized and has many functional groups (–OH, phenolics) that make the biopolymer a convenient substrate for materials manufacturing by the industry. The present study thus describes grafting of lignin onto nanostructured silica SBA-15 (Santa Barbara amorphous 15) by first silylating lignin with triethoxychlorosilane followed by treatment of silylated lignin with SBA-15. The resulting nanocomposite denoted as LIG–SBA-15-G was then characterized by powder X-ray diffraction, infra-red (FTIR), ³¹P nuclear magnetic resonance (³¹P NMR), N₂ adsorption (BET), scanning and transmission electron micrographs (SEM and TEM) and thermogravimetric analysis (TGA). X-ray data showed that LIG–SBA-15-G exhibited hexagonal structure closely similar to that observed for the SBA-15 host. FTIR of LIG–SBA-15-G showed characteristic absorption bands from lignin and attenuated Si–OH band due to its conversion to Si–O–Si ether bonds. Whereas, ³¹P NMR revealed that the majority of hydroxyl groups in lignin were replaced by Si–O–LIG ether bonds in LIG–SBA-15-G. SEM images of LIG–SBA-15-G displayed little changes in the macroscopic structure as compared to SBA-15. TEM images showed some disordered area in LIG–SBA-15-G and the grafted lignin appeared as black film on the silica surface. Using BET analysis the surface area of LIG–SBA-15-G was found to be 560 m² g⁻¹. Finally, TGA showed that LIG–SBA-15-G was more thermally stable than lignin and contained 13 % w/w lignin. Understanding the physicochemical and structural properties of the resulting lignin-nanosilica hybrid material should help engineer a robust and sustainable biomaterial suitable for various application, e.g. removal of contaminants from contaminated water. DA - 2012/04/28 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e24f4ef8-8a83-404b-b105-00c3ac698b1a ER - TY - JOUR TI - Monitoring the switch : the Warburg effect and targeted proteomic analysis of cancer metabolism DO - 10.2174/157016412799746263 AU - Murphy, J. Patrick AU - Côté, Patrice D. AU - Pinto, Devanand M. T2 - Current Proteomics VL - 9 IS - 1 SP - 26 EP - 39 KW - Cancer KW - glycolysis KW - MRM KW - targeted proteomics KW - warburg effect AB - Cancer cells dramatically alter their metabolism in order to increase the production rate of intermediates required for nucleic and fatty acid biosynthesis in rapidly proliferating cells. While not well understood, dysregulation of oncogenes and tumour suppressors appears to result in the altered expression of specific isoforms of glycolysis proteins. A full understanding of glycolytic alterations in cancer through a systems biology approach requires tools to observe changes in the set of proteins that make up the glycolytic proteome. We propose that a targeted proteomics approach employing multiple reaction monitoring (MRM) is an excellent startegy to quatitatively monitor sets of proteins, such as those making up the glycolytic proteome. MRM is particularly well suited to proteins of glycolysis as they are of moderate to high abundance. Such systems-based efforts provide a means to understand the mechanisms for an altered glycolytic proteome in cancer, perhaps leading to novel drup targets and metabolic signatures for use in cancer prognosis. DA - 2012/04/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bfaa5129-2164-4a04-a502-9c01f3be342f ER - TY - JOUR TI - Laboratory desalination experiments with some algal toxins DO - 10.1016/j.desal.2012.02.014 AU - Laycock, Maurice V. AU - Anderson, Donald M. AU - Naar, Jerome AU - Goodman, Allan AU - Easy, Dorothy J. AU - Donovan, Mary Anne AU - Li, Aifeng AU - Quilliam, Michael A. AU - Al Jamali, Ebrahim AU - Alshihi, Rashid T2 - Desalination VL - 293 SP - 1 EP - 6 KW - HAB toxins KW - red tide KW - detoxification KW - saxitonxin KW - domoic acid KW - okadaic acid KW - brevetoxins AB - Over the last several decades, countries throughout the world have experienced an escalating and worrisome trend in the incidence of harmful algal blooms (HABs). A concern is that highly potent algal toxins might be retained in the treated water, posing a threat to human health. Seawater contaminated with saxitoxins, domoic acid, okadaic acid, and brevetoxins was desalinated using small (b100 mL capacity) reverse osmosis and distillation equipment. Analyses of desalinated water samples indicated efficient removal of the four toxins to greater than 99%, except brevetoxins for which some carry-over was observed during distillation. Hypochlorite concentrations of 4 ppm or higher were sufficient to react with all of the saxitoxins, domoic acid and okadaic acid in the samples that contained initial toxin concentrations up to 1250 ng mL⁻¹ Brevetoxins appeared to be unaffected in experiments in which the toxins were exposed to up to 30 ppm hypochlorite in seawater at 35 °C for 60 min. These results and their implications in terms of desalination plant design and operation are discussed. DA - 2012/03/23 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2c0045b3-6d2e-4e26-abff-624264363223 ER - TY - JOUR TI - Ligand and pathogen specificity of the Atlantic salmon serum C-type lectin DO - 10.1016/j.bbagen.2012.09.019 AU - Uribe, Elke AU - Steele, Thomas J. AU - Richards, Robert C. AU - Ewart, K. Vanya T2 - Biochimica et Biophysica Acta (BBA) - General Subjects VL - 1830 IS - 1 SP - 2129 EP - 2138 KW - Atlantic salmon KW - Salmo salar KW - C-type lectin KW - Glycan array KW - Lipopolysaccharide KW - Pathogen recognition AB - Background: An Atlantic salmon (Salmo salar) C-type lectin (SSL) binds to mannose and related sugars as well as to the surface of Aeromonas salmonicida. To characterize this lectin as a pathogen recognition receptor in salmon, aspects of its interaction with molecules and with intact pathogens were investigated. Methods: SSL was isolated using whole-yeast-affinity and mannan-affinity chromatography. The binding of SSL to the two major surface molecules of A. salmonicida, lipopolysaccharide (LPS) and A-layer protein was investigated by western blotting and enzyme-linked immunosorbent assays. Microbial binding specificity of SSL was examined by whole cell binding assays using a range of species. Carbohydrate ligand specificity of SSL was examined using glycan array analysis and frontal affinity chromatography. Results: SSL showed binding to bacteria and yeast including, Pseudomonas fluorescens, A. salmonicida, A. hydrophila, Pichia pastoris, and Saccharomyces cerevisiae, but there was no detectable binding to Yersinia ruckeri. In antimicrobial assays, SSL showed no activity against Escherichia coli, Bacillus subtilis, S. cerevisiae, or A. salmonicida, but it was found to agglutinate E. coli. The major surface molecule of A. salmonicida recognized by SSL was shown to be LPS and not the A-layer protein. LPS binding was mannose-inhibitable. Glycans containing N-acetylglucosamine were shown to be predominant ligands. Conclusion: SSL has a distinct ligand preference while allowing recognition of a wide variety of related carbohydrate structures. DA - 2012/09/29 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f363072d-36c8-4adb-bb57-f8e6affda4d5 ER - TY - JOUR TI - A convenient method for electron tomography sample preparation using a focused ion beam DO - 10.1002/jemt.22044 AU - Wang, Xiongyao AU - Lockwood, Ross AU - Vick, Doug AU - Li, Peng AU - Meldrum, Al AU - Malac, Marek T2 - Microscopy Research and Technique VL - 75 IS - 9 SP - 1165 EP - 1169 KW - electron tomography; sample preparation; FIB; high tilt range; thin film deposition AB - Here we report a new sample preparation method for three-dimensional electron tomography. The method uses the standard film deposition and focused ion beam (FIB) methods to significantly reduce the problems arising from the projected sample thickness at high tilt angles. The method can be used to prepare tomography samples that can be imaged up to a ±75° tilt range which is sufficient for many practical applications. The method can minimize the problem of Ga+ contamination, as compared to the case of FIB preparation of rod-shaped samples, and provides extended thin regions for standard 2D projection analyses. DA - 2012/03/27 PY - 2012 PB - Wiley LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0a699e58-b9b8-4753-9912-793888be0425 ER - TY - JOUR TI - Preparation and evaluation of hydrotreating catalysts based on activated carbon derived from oil sand petroleum coke DO - 10.1016/j.apcata.2012.07.014 AU - Shi, Yu AU - Chen, Jinwen AU - Chen, Jian AU - Macleod, Robb A. AU - Malac, Marek T2 - Applied Catalysis A: General SN - 0926-860X VL - 441-442 SP - 99 EP - 107 KW - oil sand petroleum (OSP) coke; activated carbon (AC); hydrotreating; heavy vacuum gas oil (HVGO) AB - Novel Ni–Mo/activated carbon (AC) hydrotreating catalysts were prepared and evaluated for upgrading heavy vacuum gas oil (HVGO). The AC supports were derived from Alberta oil sand petroleum coke, i.e. fluid coke and/or delayed coke, hereafter referred to as OSP coke, through a chemical process. The BET surface area was as high as 2194 m2/g for the fluid coke derived AC and 2357 m2/g for the delayed coke derived AC. Both ACs contained a large number of micropores with pore volume as high as 1.2 cm3/g. Ni and Mo based active component precursors could be easily loaded on the activated carbon supports by chemical impregnation of nickel nitrate and ammonium molybdate followed by calcination in nitrogen at 773 K without further modification or oxidation treatment to the activated carbons. Scanning electron microscopy (SEM) observation showed highly porous surface structure of the bare activated carbon supports and well dispersed metal (oxide) precursor nanoparticles of 30–50 nm loaded on the AC supports. For comparison, two reference catalysts were also prepared by the same procedure but using commercial activated carbon and porous alumina as supports. After catalyst activation by sulfiding, the hydrotreating performance of the prepared catalysts was evaluated in a magnetically stirred autoclave with a HVGO feedstock to examine their hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) activities. Two commercial hydrotreating catalysts were also tested and compared under similar conditions with the same feed. The results showed that the catalysts based on the activated carbon supports prepared from OSP coke had better hydrotreating performance than the other catalysts. Scanning transmission electron microscopy (STEM) characterization of the catalysts after activation showed that small particles of nanostructure (2–5 nm in size) were evenly embedded in the carbon matrix except for some bigger particles that were located on the catalyst surface. Energy dispersive X-ray (EDX) spectroscopy revealed that these particles were composed of Ni, Mo and S elements. The dispersed nanoparticles formed the active sites and were responsible for the observed high HDS and HDN activity. Elemental analysis and surface characterization of the spent catalysts showed that the formation of coke precursors was favored on the alumina supported catalyst, which resulted in catalyst deactivation. DA - 2012/07/20 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5a22eda3-33bf-4441-a69b-dfb8ac161d74 ER - TY - JOUR TI - Tissue-specific differential induction of duplicated fatty acid-binding protein genes by the peroxisome proliferator, clofibrate, in zebrafish (Danio rerio) DO - 10.1186/1471-2148-12-112 AU - Venkatachalam, Ananda B. AU - Lall, Santosh P. AU - Denovan-Wright, Eileen M. AU - Wright, Jonathan M. T2 - BMC Evolutionary Biology VL - 12 IS - 112 SP - 1 EP - 14 AB - Background: Force, Lynch and Conery proposed the duplication-degeneration-complementation (DDC) model in which partitioning of ancestral functions (subfunctionalization) and acquisition of novel functions (neofunctionalization) were the two primary mechanisms for the retention of duplicated genes. The DDC model was tested by analyzing the transcriptional induction of the duplicated fatty acid-binding protein (fabp) genes by clofibrate in zebrafish. Clofibrate is a specific ligand of the peroxisome proliferator-activated receptor (PPAR); it activates PPAR which then binds to a peroxisome proliferator response element (PPRE) to induce the transcriptional initiation of genes primarily involved in lipid homeostasis. Zebrafish was chosen as our model organism as it has many duplicated genes owing to a whole genome duplication (WGD) event that occurred ~230-400 million years ago in the teleost fish lineage. We assayed the steady-state levels of fabp mRNA and heterogeneous nuclear RNA(hnRNA) transcripts in liver, intestine, muscle, brain and heart for four sets of duplicated fabp genes, fabp1a/ fabp1b.1/fabp1b.2, fabp7a/fabp7b, fabp10a/fabp10b and fabp11a/fabp11b in zebrafish fed different concentrations of clofibrate. Result: Electron microscopy showed an increase in the number of peroxisomes and mitochondria in liver and heart, respectively, in zebrafish fed clofibrate. Clofibrate also increased the steady-state level of acox1 mRNA and hnRNA transcripts in different tissues, a gene with a functional PPRE. These results demonstrate that zebrafish is responsive to clofibrate, unlike some other fishes. The levels of fabp mRNA and hnRNA transcripts for the four sets of duplicated fabp genes was determined by reverse transcription, quantitative polymerase chain reaction (RT-qPCR). The level of hnRNA coded by a gene is an indirect estimate of the rate of transcriptional initiation of that gene. Clofibrate increased the steady-state level of fabp mRNAs and hnRNAs for both the duplicated copies of fabp1a/ fabp1b.1, and fabp7a/fabp7b, but in different tissues. Clofibrate also increased the steady-state level of fabp10a and fabp11a mRNAs and hnRNAs in liver, but not for fabp10b and fabp11b. Conclusion: Some duplicated fabp genes have, most likely, retained PPREs, but induction by clofibrate is over-ridden by an, as yet, unknown tissue-specific mechanism(s). Regardless of the tissue-specific mechanism(s), transcriptional control of duplicated zebrafish fabp genes by clofibrate has markedly diverged since the WGD event. DA - 2012/07/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 118b7828-680e-4725-826a-bb07fcc8b390 ER - TY - JOUR TI - A larval zebrafish model of bipolar disorder as a screening platform for neuro-therapeutics DO - 10.1016/j.bbr.2012.05.043 AU - Ellis, Lee David AU - Soanes, Kelly Howard T2 - Behavioural Brain Research VL - 233 IS - 2 SP - 450 EP - 457 KW - Zebrafish larvae KW - Disease model KW - Hyperactivity KW - Pentylenetrazole KW - Bipolar disorder AB - Modelling neurological diseases has proven extraordinarily difficult due to the phenotypic complexity of each disorder. The zebrafish has become a useful model system with which to study abnormal neurological and behavioural activity and holds promise as a model of human disease. While most of the disease modelling using zebrafish has made use of adults, larvae hold tremendous promise for the highthroughput screening of potential therapeutics. The further development of larval disease models will strengthen their ability to contribute to the drug screening process. Here we have used zebrafish larvae to model the symptoms of bipolar disorder by treating larvae with sub-convulsive concentrations of the GABA antagonist pentylenetetrazol (PTZ). A number of therapeutics that act on different targets, in addition to those that have been used to treat bipolar disorder, were tested against this model to assess its predictive value. Carbamazepine, valproic acid, baclofen and honokiol, were found to oppose various aspects of the PTZ-induced changes in activity. Lidocaine and haloperidol exacerbated the PTZ-induced activity changes and sulpiride had no effect. By comparing the degree of phenotypic rescue with the mechanism of action of each therapeutic we have shown that the low-concentration PTZ model can produce a number of intermediate phenotypes that model symptoms of bipolar disorder, may be useful in modelling other disease states, and will help predict the efficacy of novel therapeutics. DA - 2012/06/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a9eebbdc-f60e-4896-9163-0f43a787550f ER - TY - JOUR TI - Mono- and digalactosyldiacylglycerols : potent nitric oxide inhibitors from the marine microalga Nannochloropsis granulata DO - 10.1007/s10811-012-9869-2 AU - Banskota, Arjun H. AU - Stefanova, Roumiana AU - Gallant, Pamela AU - McGinn, Patrick J. T2 - Journal of Applied Phycology VL - 25 IS - 2 SP - 349 EP - 357 KW - Nannochloropsis granulata KW - Monogalactosyldiacylglycerol KW - Digalactosyldiacylglycerol KW - Nitric oxide KW - Inducible nitric oxide synthase AB - Chemical investigation of a marine microalga, Nannochloropsis granulata, led to the isolation of four digalactosyldiacylglycerols namely, (2S)-1-O-eicosapentaenoyl-2-O-palmitoyl-3-O-(β-D-galactopyranosyl-6-1α-D-galactopyranosyl)-glycerol (1), (2S)-1-O-eicosapentaenoyl-2-O-palmitoleoyl-3-O-(β-D-galactopyranosyl-6-1α-D-galactopyranosyl)- glycerol (2), (2S)-1-O-eicosapentaenoyl-2-O-myristoyl-3-O-(β-D-galactopyranosyl-6-1α-D-galactopyranosyl)-glycerol (3), and (2S)-1,2-bis-O-eicosapentaenoyl-3-O-(β-D-galactopyranosyl-6-1α-D-galactopyranosyl)-glycerol (4), together with their monogalactosyl analogs (5–8). Among the isolated galactolipids 2 and 3 were new natural products. Complete stereochemistry of 1, 4, 5, 7, and 8 was determined for the first time by both spectroscopic techniques and classical degradation methods. Both mono- and digalactosyldiacylglycerols isolated from N. granulata poss e s s ed s t rong n i t r i c oxide (NO) inhibi tory a c t ivi ty against lipopolysaccharide-induced NO production in RAW264.7 macrophage cells through downregulation of inducible nitric oxide synthase expression indicating the possible use as anti-inflammatory agents. DA - 2012/07/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6e7f8ad5-2c88-44cf-a189-5c5469f0fcf8 ER - TY - JOUR TI - Study of possible combined toxic effects of azaspiracid-1 and okadaic acid in mice via the oral route DO - 10.1016/j.toxicon.2012.06.007 AU - Aune, Tore AU - Espenes, Arild AU - Bunæs Aasen, John A. AU - Quilliam, Michael A. AU - Hess, Philipp AU - Larsen, Stig T2 - Toxicon VL - 60 IS - 5 SP - 895 EP - 906 KW - Azaspiracid KW - Okadaic acid KW - Toxicity AB - Toxins from the okadaic acid (OA) and azaspiracid (AZA) group cause considerable negative health effects in consumers when present in shellfish above certain levels. The main symptoms, dominated by diarrhoea, are caused by damage to the gastrointestinal (GI) tract. Even though OA and AZAs exert toxicity via different mechanisms, it is important to find out whether they may enhance the health effects if present together since they act on the same organs and are regulated individually. In this study, the main issue was the possibility of enhanced lethality in mice upon combined oral exposure to OA and AZA1. In addition, pathological effects in several organs and effects on absorption from the GI tract were studied. Although the number of mice was small due to low availability of AZA1, the results indicate no additive or synergistic effect on lethality when AZA1 and OA were given together. Similar lack of increased toxicity was observed concerning pathological effects that were restricted to the GI-tract. OA and AZA1 were absorbed from the GI-tract to a very low degree, and when given together, uptake was reduced. Taken together, these results indicate that the present practice of regulating toxins from the OA and AZA group individually does not present an unwanted increased risk for consumers of shellfish. DA - 2012/06/28 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 58a147fe-2333-41ad-ba99-bc075d286263 ER - TY - JOUR TI - Toxins in mussels (Mytilus galloprovincialis) associated with diarrhetic shellfish poisoning episodes in China DO - 10.1016/j.toxicon.2012.04.339 AU - Li, Aifeng AU - Ma, Jinggang AU - Cao, Jijuan AU - McCarron, Pearse T2 - Toxicon VL - 60 IS - 3 SP - 420 EP - 425 KW - Diarrhetic shellfish poinsoning (DSP) KW - Lipophilic toxins KW - Fatty acid esters KW - Mytilus galloprovincialis KW - LC-MS/MS AB - More than 200 people in China suffered illness with symptoms of diarrhetic shellfish poisoning (DSP) following consumption of mussels (Mytilus galloprovincialis). The event occurred in the cities of Ningbo and Ningde near the East China Sea in May, 2011. LC–MS/ MS analysis showed that high concentrations of okadaic acid, dinophysistoxin-1, and their acyl esters were responsible for the incidents. The total concentration was more than 40 times the EU regulatory limit of 160 μg OA eq./kg. Pectentoxin-2 and its seco-acids were also present in the mussels. Additionally, yessotoxins were found to be responsible for positive mouse bioassay results on scallop (Patinopecten yessoensis) and oyster (Crassostrea talienwhanensis) samples collected from the North Yellow Sea in June, 2010. This work shows that high levels of lipophilic toxins can accumulate in shellfish from the Chinese coast and it emphasises that adequate chemical analytical methodologies are needed for monitoring purposes. Further research is required to broaden the knowledge on the occurrence of lipophilic toxins in Chinese shellfish. DA - 2012/04/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4e3f5a04-6be5-4099-bfb6-f9e652db8c8b ER - TY - JOUR TI - Identification of Pinnatoxins and discovery of their fatty acid Ester Metabolites in mussels (Mytilus edulis) from Eastern Canada DO - 10.1021/jf204824s AU - McCarron, Pearse AU - Rourke, Wade A. AU - Hardstaff, William AU - Pooley, Brandy AU - Quilliam, Michael A. T2 - Journal of Agricultural and Food Chemistry VL - 60 IS - 6 SP - 1437 EP - 1446 KW - Pinnatoxins KW - shellfish KW - Canada KW - fatty acids KW - esters KW - metabolites KW - LC-MS AB - Pinnatoxins are a group of fast-acting cyclic imine toxins previously identified in shellfish from Asia, the southern Pacific, and northern Europe. In this work pinnatoxins were detected in mussels from locations across the eastern coast of Canada. Pinnatoxin G (6) was the major structural variant present, sometimes at levels >80 μg/kg, whereas much lower levels of pinnatoxin A (1) were detected in some samples. Increased concentrations were observed following base hydrolysis of extracts, leading to the discovery by LC-MS of a range of fatty acid esters of 6. Information on the structures of these acylated derivatives was provided through a series of mass spectrometric experiments, supported by partial synthesis, and it is proposed that the compounds are 28-O-acyl esters of 6. Although acyl esters of a range of other phycotoxins are known to form as metabolites in shellfish, this is the first report of their existence for this particular toxin class. The occurrence of pinnatoxins in North American shellfish further highlights the international distribution of these toxins. DA - 2012/01/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e326abc6-7773-4360-9cce-556de291efbc ER - TY - JOUR TI - Assessment of the bioenergy and bioremediation potentials of the microalga Scenedesmus sp. AMDD cultivated in municipal wastewater effluent in batch and continuous mode DO - 10.1016/j.algal.2012.05.001 AU - McGinn, Patrick J. AU - Dickinson, Kathryn E. AU - Park, Kyoung C. AU - Whitney, Crystal G. AU - MacQuarrie, Scott P. AU - Black, Frank J. AU - Frigon, Jean-Claude AU - Guiot, Serge R. AU - O'Leary, Stephen J. B. T2 - Algal Research VL - 1 IS - 2 SP - 155 EP - 165 KW - Microalgae KW - Bioenergy KW - Anaerobic digestion KW - Photosynthesis KW - Wastewater KW - Methane AB - Municipal wastewater is a major source of nutrients and pollutants to freshwater and marine ecosystems and current treatment technologies are either expensive or only partially effective at removing them. We cultivated the alga Scenedesmus sp. AMDD at different pH in chemostats and batch photobioreactors in wastewater obtained from a local treatment plant. In batch mode, biomass productivities averaged 130 mg dry weight L⁻¹d⁻¹, with no significant effect of growth pH detected. Maximum nitrogen and phosphorus removal rates were equivalent to 7% and 0.7% of the biomass productivity rates. Average hydraulic retention times for 90% N and P removal ranged from 6.55 to 6.65 days and 6.50–6.56 days, respectively. Recovered biomass yields ranged from 0.23 to 0.65 kg m⁻³ wastewater, equivalent to approximately 5–15 MJ bioenergy m⁻³ wastewater based on an average calorific value of 23 MJ kg⁻¹ d.w. algal biomass. Approximately 65% of energy equivalent could potentially be recovered from the biomass through anaerobic digestion to methane. Cellular N and P content varied, with cells held longer in stationary phase showing higher C:N and C:P ratios indicative of N- and Plimitation, respectively. Analysis of trace metals in the algal biomass indicated near total depletion of Fe, Zn and Cd from the wastewater, and lower, but substantial, uptake and/or adsorption of seven other elements. Cultivation in 2 L continuous chemostats containing wastewater was also conducted. Biomass productivities in chemostats were almost 2-fold greater than the maximum rates in batch cultures. Dissolved N and P in chemostats were both either undetectable or >99% reduced compared to the wastewater. Production of bioenergy from the chemostats was estimated to be roughly 5.3–6.1 MJ m⁻³d⁻¹, significantly higher than in batch culture DA - 2012/04/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ff1b3a44-d7e9-47b7-8b06-693368ad2171 ER - TY - JOUR TI - Dereplication, residual complexity, and rational naming : the case of the Actaea Triterpenes DO - 10.1021/np200878s AU - Qiu, Feng AU - Imai, Ayano AU - McAlpine, James B. AU - Lankin, David C. AU - Burton, Ian AU - Karakach, Tobias AU - Farnsworth, Norman R. AU - Chen, Shao-Nong AU - Pauli, Guido F. T2 - Journal of Natural Products VL - 75 IS - 3 SP - 432 EP - 443 AB - The genus Actaea (including Cimicifuga) has been the source of ~200 cycloartane triterpenes. While they are major bioactive constituents of complementary and alternative medicines, their structural similarity is a major dereplication problem. Moreover, their trivial names seldom indicate the actual structure. This project develops two new tools for Actaea triterpenes that enable rapid dereplication of more than 170 known triterpenes and facilitates elucidation of new compounds. A predictive computational model based on classification binary trees (CBTs) allows in silico determination of the aglycone type. This tool utilizes the Me ¹H NMR chemical shifts and has potential to be applicable to other natural products. Actaea triterpene dereplication is supported by a new systematic naming scheme. A combination of CBTs, ¹H NMR deconvolution, characteristic ¹H NMR signals, and quantitative ¹H NMR (qHNMR) led to the unambiguous identification of minor constituents in residually complex triterpene samples. Utilizing a 1.7 mm cryo-microprobe at 700 MHz, qHNMR enabled characterization of residual complexity at the 10–20 μg level in a 1–5 mg sample. The identification of five co-occurring minor constituents, belonging to four different triterpene skeleton types, in a repeatedly purified natural product emphasizes the critical need for the evaluation of residual complexity of reference materials, especially when used for biological assessment. DA - 2012/02/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 776ff74e-aaf1-4be1-8169-e67b92693106 ER - TY - JOUR TI - Profiling phlorotannins in brown Macroalgae by liquid chromatography-high resolution mass spectronmetry DO - 10.1002/pca.2354 AU - Steevensz, Aaron J. AU - MacKinnon, Shawna L. AU - Hankinson, Rachael AU - Craft, Cheryl AU - Connan, Solène AU - Stengel, Dagmar B. AU - Melanson, Jeremy E. T2 - Phytochemical Analysis VL - 23 IS - 5 SP - 547 EP - 553 KW - High resolution mass spectrometry KW - hydrophilic interaction chromatography KW - brown seaweed KW - phlorotannins KW - polyphenols AB - Introduction – Phlorotannins, phenolic compounds produced exclusively by Phaeophyceae (brown algae), have recently been associated with a wide variety of beneficial bioactivities. Several studies have measured the total phenolic content in extracts from various species, but little characterisation of individual phlorotannin components has been demonstrated. Objective – The purpose of this study was to develop a liquid chromatography–mass spectrometry (LC-MS) based method for rapid profiling of phlorotannins in brown algae. Methodology – Phlorotannin-enriched extracts from five phaeophyceaen species were analysed by ultrahigh-pressure liquid chromatography (UHPLC) operating in hydrophilic interaction liquid chromatography (HILIC) mode combined with high resolution mass spectrometry (HRMS). The method was optimised using an extract of Fucus vesiculosus; separation was achieved in less than 15 min. The basic mobile phase enhanced negative-ion electrospray ionisation (ESI), and generated multiply charged ions that allowed detection of high molecular weight phlorotannins. Results – The phlorotannin profiles of Pelvetia canaliculata, Fucus spiralis, F. vesiculosus, Ascophyllum nodosum and Saccharina longicruris differed significantly. Fucus vesiculosus yielded a high abundance of low molecular weight (< 1200 Da) phlorotannins, while P. canaliculata exhibited a more evenly distributed profile, with moderate degrees of polymerisation ranging from 3 to 49. HRMS enabled the identification of phlorotannins with masses up to 6000 Da using a combination of accurate mass and ¹³C isotopic patterns. Conclusion – The UHPLC-HRMS method described was successful in rapidly profiling phlorotannins in brown seaweeds based on their degree of polymerisation. HILIC was demonstrated to be an effective separation mode, particularly for low molecular weight phlorotannins. DA - 2012/02/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 81d76e89-c91a-4067-8e2f-e70b58119de9 ER - TY - JOUR TI - Analysis of paralytic shellfish toxins and their metabolites in shellfish from the North Yellow Sea of China DO - 10.1080/19440049.2012.699005 AU - Li, A. AU - Ma, J. AU - Cao, J. AU - Wang, Q. AU - Yu, R. AU - Thomas, K. AU - Quilliam, M. A. T2 - Food Additives & Contaminants : Part A VL - 29 IS - 9 SP - 1455 EP - 1464 KW - paralytic shellfish toxins (PST); metabolite; LC-MS/MS; Patinopecten yessoensis; Saxidomus purpuratus AB - Samples of toxic scallop (Patinopecten yessoensis) and clam (Saxidomus purpuratus) collected on the northern coast of China from 2008 to 2009 were analysed. High-performance liquid chromatography with post-column oxidation and fluorescence detection was used to determine the profile of the main paralytic shellfish poisoning (PSP) toxins in these samples and their total toxicity. Hydrophilic interaction liquid ion chromatography with mass spectrometric detection confirmed the toxin profile and detected several metabolites in the shellfish. Results show that C1/2 toxins were the most dominant toxins in the scallop and clam samples. However, GTX1/4 and GTX2/3 were also present. M1 was the predominant metabolite in all the samples, but M3 and M5 were also identified, along with three previously unreported presumed metabolites, M6, M8 and M10. The results indicate that the biotransformation of toxins was species specific. It was concluded that the reductive enzyme in clams is more active than in scallops and that an enzyme in scallops is more apt to catalyse hydrolysis of both the sulfonate moiety at the N-sulfocabamoyl of C toxins and the 11-hydroxysulfate of C and GTX toxins to produce metabolites. This is the first report of new metabolites of PSP toxins in scallops and clams collected in China. DA - 2012/07/24 PY - 2012 PB - Taylor & Francis LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0db54ae3-3128-40c5-a16b-eb4dddb2d10e ER - TY - JOUR TI - Limitations on accurate shape determination using amplitude modulation atomic force microscopy DO - 10.1016/j.ultramic.2012.01.016 AU - Eves, B. J. AU - Green, R. G. T2 - Ultramicroscopy VL - 115 SP - 14 EP - 20 KW - atomic forcemicroscopy(AFM); measurement ofshape/form; errors andlimitations AB - The limitations of amplitude modulation atomic force microscopy to accurately measure the shape or form of features are investigated. The control feedback loop and the dynamics of the cantilever limit the response time of the atomic force microscope. Simply subtracting appropriately scaled amplitude (error) signal from the topography data significantly improves the accuracy of the data and can correct for the slow response time of the feedback loop. Two mechanisms were found to induce topographic errors independent of scan speed. The first is the change in tip/surface interaction at a step edge observed by comparison with results from a ‘virtual’ sample. The second is due to friction between the probe and sample but only for a specifically oriented step edge determined by the direction of oscillation of the cantilever. DA - 2012/02/07 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8fd90fa3-4521-436c-b0f7-277b339ad0d6 ER - TY - JOUR TI - State-of-the art comparability of corrected emission spectra. 2. Field laboratory assessment of calibration performance using spectral fluorescence standards DO - 10.1021/ac203451g AU - Resch-Genger, Ute AU - Bremser, Wolfram AU - Pfeifer, Dietmar AU - Spieles, Monika AU - Hoffmann, Angelika AU - DeRose, Paul C. AU - Zwinkels, Joanne C. AU - Gauthier, François AU - Ebert, Bernd AU - Taubert, R. Dieter AU - Voigt, Jan AU - Hollandt, Jörg AU - Macdonald, Rainer T2 - Analytical Chemistry VL - 84 IS - 9 SP - 3899 EP - 3907 AB - In the second part of this two-part series on the state-of-the-art comparability of corrected emission spectra, we have extended this assessment to the broader community of fluorescence spectroscopists by involving 12 field laboratories that were randomly selected on the basis of their fluorescence measuring equipment. These laboratories performed a reference material (RM)- based fluorometer calibration with commercially available spectral fluorescence standards following a standard operating procedure that involved routine measurement conditions and the data evaluation software LINKCORR developed and provided by the Federal Institute for Materials Research and Testing (BAM). This instrument-specific emission correction curve was subsequently used for the determination of the corrected emission spectra of three test dyes, X, QS, and Y, revealing an average accuracy of 6.8% for the corrected emission spectra. This compares well with the relative standard uncertainties of 4.2% for physical standard-based spectral corrections demonstrated in the first part of this study (previous paper in this issue) involving an international group of four expert laboratories. The excellent comparability of the measurements of the field laboratories also demonstrates the effectiveness of RM-based correction procedures. DA - 2012/02/28 PY - 2012 PB - American Chemical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 941f8580-4088-4531-98fc-faeddd43ea2a ER - TY - JOUR TI - State-of-the art comparability of corrected emission spectra.1. Spectral correction with physical transfer standards and spectral fluorescence standards by expert laboratories DO - 10.1021/ac2034503 AU - Resch-Genger, Ute AU - Bremser, Wolfram AU - Pfeifer, Dietmar AU - Spieles, Monika AU - Hoffmann, Angelika AU - DeRose, Paul C. AU - Zwinkels, Joanne C. AU - Gauthier, François AU - Ebert, Bernd AU - Taubert, R. Dieter AU - Monte, Christian AU - Voigt, Jan AU - Hollandt, Jörg AU - Macdonald, Rainer T2 - Analytical Chemistry VL - 84 IS - 9 SP - 3889 EP - 3898 AB - The development of fluorescence applications in the life and material sciences has proceeded largely without sufficient concern for the measurement uncertainties related to the characterization of fluorescence instruments. In this first part of a two-part series on the state-of-the-art comparability of corrected emission spectra, four National Metrology Institutes active in high-precision steady-state fluorometry performed a first comparison of fluorescence measurement capabilities by evaluating physical transfer standard (PTS)-based and reference material (RM)-based calibration methods. To identify achievable comparability and sources of error in instrument calibration, the emission spectra of three test dyes in the wavelength region from 300 to 770 nm were corrected and compared using both calibration methods. The results, obtained for typical spectrofluorometric (0°/90° transmitting) and colorimetric (45°/0° front-face) measurement geometries, demonstrated a comparability of corrected emission spectra within a relative standard uncertainty of 4.2% for PTS- and 2.4% for RM-based spectral correction when measurements and calibrations were performed under identical conditions. Moreover, the emission spectra of RMs F001 to F005, certified by BAM, Federal Institute for Materials Research and Testing, were confirmed. These RMs were subsequently used for the assessment of the comparability of RM-based corrected emission spectra of field laboratories using common commercial spectrofluorometers and routine measurement conditions in part 2 of this series (subsequent paper in this issue). DA - 2012/02/28 PY - 2012 PB - American Chemical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e5a79d00-3eb4-4582-93ef-7b3733c89ffb ER - TY - JOUR TI - Strategic identification of in vitro metabolites of 13-desmethyl spirolide C using liquid chromatography/high-resolution mass spectrometry DO - 10.1002/rcm.5336 AU - Hui, Joseph P. M. AU - Grossert, J. Stuart AU - Cutler, Murray J. AU - Melanson, Jeremy E. T2 - Rapid Communications in Mass Spectrometry VL - 26 IS - 3 SP - 345 EP - 354 AB - A strategy to identify metabolites of a marine biotoxin, 13-desmethyl spirolide C, has been developed using liquid chromatography coupled to high-resolution mass spectrometry (LC/HRMS). Metabolites were generated in vitro through incubation with human liver microsomes. A list of metabolites was established by selecting precursor ions of a common fragment ion characteristic of the spirolide toxin which was known to contain a cyclic imine ring. Accurate mass measurements were subsequently used to confirm the molecular formula of each biotransformation product. Using this approach, a total of nine phase I metabolites was successfully identified with deviations of mass accuracy less than 2 ppm. The biotransformations observed included hydroxylation, dihydroxylation, oxidation of a quaternary methyl group to hydroxymethyl or carboxylic acid groups, dehydrogenation and hydroxylation, as well as demethylation and dihydroxylation reactions. In a second step, tandem mass spectrometry (MS/MS) was performed to elucidate structures of the metabolites. Using the unique fragment ions in the spectra, the structures of the three major metabolites, 13,19-didesmethyl-19-carboxy spirolide C, 13,19-didesmethyl-19-hydroxymethyl spirolide C and 13-desmethyl-17-hydroxy spirolide C, were assigned. Levels of 13-desmethyl spirolide C and its metabolites were monitored at selected time points over a 32-h incubation period with human liver microsomes. It was determined that 13,19-didesmethyl-19-carboxy spirolide C became the predominant metabolite after 2 h of incubation. The stability plot of 13-desmethyl spirolide C showed first-order kinetics for its metabolism and the intrinsic clearance was calculated to be 41 mL/min/mg, suggesting first-pass metabolism may contribute to limiting oral toxicity of 13-desmethyl spirolide C. DA - 2012/01/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c0cbac7e-84bd-46ef-aa3a-335848a448ff ER - TY - JOUR TI - Gas-substrate heat exchange during cold-gas dynamic spraying DO - 10.1007/s11666-012-9828-0 AU - McDonald, A. G. AU - Ryabinin, A. N. AU - Irissou, É. AU - Legoux, J.-G. T2 - Journal of Thermal Spray Technology VL - 22 IS - 2-3 SP - 391 EP - 397 KW - Cold spraying KW - heat transfer KW - jet impingement KW - Peclét number KW - temperature distribution AB - In this study, the temperature distribution of the surfaces of several substrates under an impinging gas jet from a cold spray nozzle was determined. A low-pressure cold-gas dynamic spraying unit was used to generate a jet of hot compressed nitrogen that impinged upon flat substrates. Computer codes based on a finite differences method were used to solve a simplified 2D temperature distribution equation for the substrate to produce nondimensional relationships between the surface temperature and the radius of the impinging fluid jet, the axial velocity of the cold spray nozzle, the substrate thickness, and the heating time. It was found that a single profile of the transient nondimensional maximum surface temperature could be used to estimate the dimensional maximum surface temperature, regardless of the value of the compressed gas temperature. It was found further that, as the thermal conductance of the substrate increased, the maximum surface temperature of the substrate beneath the gas jet decreased. Heat exchange between the substrate and the compressed gas jet during motion of the nozzle to produce heat conduction within the substrate was characterized by the nondimensional Pecle´t number. It was found that lower Pecle´t numbers produced higher temperatures within the substrate. The close agreement of the numerical results with the experimental results suggests that the nondimensionalized results may be applied to a wide range of conditions and materials. DA - 2012/10/16 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b0174a89-3ee6-4b8c-9a63-937087e1050c ER - TY - JOUR TI - Study of optical and electrical properties of ZnO/Cu/ZnO multilayers deposited on flexible substrate DO - 10.1016/j.tsf.2012.10.064 AU - Ionescu, Mihnea Ioan AU - Bensebaa, Farid AU - Luan, Ben Li T2 - Thin Solid Films VL - 525 SP - 162 EP - 166 KW - Transparent conducting oxide KW - multilayer KW - zinc oxide KW - copper KW - flexible substrate KW - sputtering AB - Transparent conducting oxide thin films have been extensively studied because they are essential elements in optoelectronic applications. In this communication, we report transparent conductive ZnO/Cu/ZnO multilayer films prepared by RF sputtering of ZnO and DC sputtering of Cu on flexible polyethylene naphthalate substrates. The optical and electrical properties of the multilayers were studied for different thicknesses of Cu and ZnO layers. Controlling the thickness of the ZnO layer for a specific Cu thickness affects the transmittance of the multilayer. Electrical properties are influenced by the thickness of ZnO and Cu layers. Sheet resistance of the stack rises with the decrease of Cu thickness and the increase of ZnO thickness. Repeated bending of the stack, after an initial 20% increase of sheet resistance, has no significant effect on the electrical performance of the multilayers. DA - 2012/10/30 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 52a62169-83d4-44cd-a441-28362c1493de ER - TY - JOUR TI - Modular ultrasonic Lysis system for rapid nucleic acid extraction and sample transfer of Bacillus spores DO - 10.4172/2157-2526.1000119 AU - Geissler, Matthias AU - Isabel, Sandra AU - Voisin, Benoît AU - Fauvel, Chantal AU - Boissinot, Maurice AU - Bergeron, Michel G. AU - Veres, Teodor T2 - Journal of Bioterrorism & Biodefense VL - 3 IS - 3 SP - 1000119-1 EP - 1000119-6 KW - Bacillus spores KW - sonication KW - spore lysis KW - PCR KW - Sample transfer AB - This paper describes the design, functioning and use of an ultrasonic modular system intended for rapid extraction and fragmentation of DNA from microbial organisms following sample collection in the field. PCR assessment of the DNA extracts revealed that the system can disrupt Bacillus atrophaeus spores, a simulant for Bacillus anthracis, in less than 1 min, providing a DNA yield equivalent to that of a commercial nucleic acid extraction method. Simulation of the transfer from a contaminated to a secure area confirmed that the sample remained confined within the module while the exterior surface can be decontaminated through immersion in a disinfectant solution. DA - 2012/11/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5bd60e26-548a-4bbf-9ae2-dda503318ab6 ER - TY - JOUR TI - Review of tissue simulating phantoms with controllable optical, mechanical and structural properties for use in optical coherence tomography DO - 10.1364/BOE.3.001381 AU - Lamouche, Guy AU - Kennedy, Brendan F. AU - Kennedy, Kelsey M. AU - Bisaillon, Charles-Etienne AU - Curatolo, Andrea AU - Campbell, Gord AU - Pazos, Valérie AU - Sampson, David D. T2 - Biomedical Optics Express VL - 3 IS - 6 SP - 1381 EP - 1398 AB - We review the development of phantoms for optical coherence tomography (OCT) designed to replicate the optical, mechanical and structural properties of a range of tissues. Such phantoms are a key requirement for the continued development of OCT techniques and applications. We focus on phantoms based on silicone, fibrin and poly(vinyl alcohol) cryogels (PVA-C), as we believe these materials hold the most promise for durable and accurate replication of tissue properties. DA - 2012/05/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : dd00bc1a-9ab5-4c00-b5ab-30cca7c028db ER - TY - JOUR TI - Mullite–YSZ multilayered environmental barrier coatings tested in cycling conditions under water vapor atmosphere DO - 10.1016/j.surfcoat.2012.08.044 AU - Mesquita-Guimarães, J. AU - Garcia, E. AU - Miranzo, P. AU - Osendi, M. I. AU - Cojocaru, C. V. AU - Lima, R. S. T2 - Surface and Coatings Technology SN - 0257-8972 VL - 209 SP - 103 EP - 109 KW - Plasma spraying KW - Environmental barrier coatings (EBCs) KW - Water vapor corrosion KW - Mullite KW - ZrO₂ AB - Plasma sprayed mullite/YSZ graded coatings on SiC substrates were examined as environmental barrier coatings (EBCs). Several coating systems with various layer arrangements were subjected to thermal aging at 1300°C in cycling (50 and 100 cycles, i.e. 100 and 200 h) conditions under rich water vapor atmosphere. The level of porosity and the crack population were quantified using cross section SEM images of these coatings. The thickness of the thermally grown silica (TGS) layer developed was estimated and the presence of cristobalite in its structure was evidenced by micro-Raman spectroscopy. Hardness and elastic modulus were also determined by the use of instrumented indentation for each layer in the different coatings. The evolution of all these parameters confirmed that EBC architectures formed by compliant porous layers resulted more effective in reducing cracks and the effects of aging than EBCs with dense graded compositions. DA - 2012/08/27 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fd17031c-5832-4e4a-9590-3bbc882f08f1 ER - TY - JOUR TI - Properties of titanium foams for biomedical application DO - 10.1002/adem.201200154 AU - Lefebvre, Louis-Philippe AU - Baril, Éric T2 - Advanced Engineering Materials Special Issue : Porous Metals and Metal Foams VL - 15 IS - 3 SP - 159 EP - 165 KW - Titanium KW - foam KW - orthopedic implant KW - microstructure KW - mechanical properties AB - Titanium foams are presently used in various load bearing orthopedic applications. Such foams are characterized by an open network of porosity with high surface area. This paper presents the structure, microstructure, and properties of titanium foams produced with a powder metallurgy process. Fully porous CpTi and Ti6Al4V cylinders and CpTi foam coating on CpTi and Ti6Al4V substrates were produced and characterized. The microstructure of the foam cell walls is representative of annealed CpTi and Ti6Al4V. Alloying elements and oxygen in solution increase the mechanical strength of the foams but lower their ductility. Ductility affects the fatigue life of the material. When CpTi foam is bonded to Ti6Al4V substrates, migration of alloying elements in the foam cell walls is observed. Good metallurgical bonding is created between the coatings and the dense substrate and shear strength above the requirements of the FDA guidelines are obtained. DA - 2012/10/16 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d19fbd29-dba7-401e-817f-28a57c7d43fd ER - TY - JOUR TI - Dry rolling-sliding wear resistance of high density PM steel parts AU - Bernier, Fabrice AU - Gauthier, Maxime AU - Baril, Éric AU - Jiang, Jiaren AU - Xue, Lijue T2 - Advances in Powder Metallurgy & Particulate Materials—2012 : Proceedings of the 2012 International Conference on Powder Metallurgy & Particulate Materials, June 10–13, Nashville, Tennessee T3 - 2012 International Conference on Powder, Metallurgy & Particulate Materials (PowderMet 2012), 10-13 June 2012, Nashville, Tennessee, USA SN - 978-0-9853397-2-2 VL - 2 IS - part 10 AB - As PM steel reach ever higher static and dynamic properties, their use in high performance applications is increasingly acknowledged by end-users. PM steels are now being pushed in applications where high wear resistance is required while maintaining good overall properties. Indeed, gears and cams can be subject to both rolling and sliding wear, leading to premature failure. This paper explores the effect of different alloys and process conditions on material loss in dry wear conditions. The impact of the rolling/sliding ratio is also studied. The PM component results are then compared those obtained for a wrought steel generally used in gear applications. The comparison shows that similar or even higher wear resistance can be reached by high density, high hardness PM steels. DA - 2012/06/13 PY - 2012 UR - http://www.mpif.org/cgi-shl/TWServer.exe?Run:SESS07_1:TradeWinds_KEY=1 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4f6a81ac-74b2-4bcc-a8b6-e5e7c5714750 ER - TY - JOUR TI - Novel high-performance lubricants for conventional and high-density compaction AU - Paris, Vincent AU - St-Laurent, Sylvain AU - Thomas, Yannig T2 - Advances in Powder Metallurgy & Particulate Materials—2012 : Proceedings of the 2012 International Conference on Powder Metallurgy & Particulate Materials, 10-13 June, Nashville, Tennessee T3 - 2012 International Conference on Powder, Metallurgy & Particulate Materials (PowderMet 2012), 10-13 June 2012, Nashville, Tennessee, USA SN - 978-0-9853397-2-2 VL - 1 IS - part 3 AB - With an ever increasing variety and complexity of PM parts being produced, many parts producers are looking for a powder feedstock that can allow for high green and sintered densities, improved filling performance, excellent lubricating properties and clean burn-off. Lubricants and other organics used as binders play a key role in responding to all these requirements. Consequently, many efforts have recently been put in the design of proper organic systems to improve the compaction and lubrication behaviour of powder mixes. This paper presents the characteristics of innovative lubricant systems under development with improved lubrication properties compared to the conventional lubricants used in PM. The focus is shared between two development axes: obtaining high green densities and lowering ejection forces. The lubricants were tested at high shear stresses on an industrial press at different compacting pressure and temperatures, which adequately mimics the conditions most parts manufacturers will encounter. DA - 2012/06/13 PY - 2012 UR - http://www.mpif.org/cgi-shl/TWServer.exe?Run:SESS21_1:TradeWinds_KEY=1 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 49c8f9aa-5847-4f5d-b1a8-8dc434b468d8 ER - TY - JOUR TI - Design and manufacturing of a representative thermoplastic composite primary aerospace structure AU - Khoun, L. AU - Wedeking, M. AU - Demaria, C. AU - Baier, H. AU - Trudel-Boucher, D. AU - Hubert, P. T2 - SAMPE International Symposium and Exhibition - Emerging Opportunities : Materials and Process Solutions T3 - Society for the Advancement of Material and Process Engineering International Symposium and Exhibition 2012 (SAMPE 2012), 21-24 May 2012, Baltimore, Maryland, USA SN - 9781934551127 KW - Aerospace structure KW - Analytical method KW - Autoclave process KW - Hat-stiffened panels KW - High temperature performance KW - High toughness KW - Manufacturing techniques KW - Mechanical performance KW - Panel design KW - Panel skin KW - Primary structures KW - Process simulations KW - Stability issues KW - Structural applications KW - Thermo-mechanical KW - Thermoplastic composite KW - Thermoset composites KW - Tooling materials KW - Chemical resistance KW - Composite materials KW - Composite structures KW - Computer simulation KW - Finite element method KW - Mechanical properties KW - Pressure vessels KW - Structure (composition) KW - Thermoplastics KW - Thermosets AB - The use of high performance thermoplastic composite structures in aerospace has seen a great increase in the past decade. Thermoplastic composites present many advantages over thermoset composites in terms of processing and performance, such as high toughness, high temperature performance, chemical resistance and low flammability. However, compared to thermoset matrices, the lack of material database and the limited knowledge available in the open literature regarding the manufacturing techniques have restrained their use to a relatively small number of composite structural applications. In this study, the design and the autoclave manufacturing of a PEEK/carbon hat-stiffened panel representative of an aerospace primary structure were investigated. Design and mechanical performances, including strength and stability issues, were first evaluated with finite element analysis and analytical methods. Process simulations were also performed to define the tooling material and geometry to be used, based on the evolution of the thermo-mechanical material properties during the autoclave process. DA - 2012/05/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f94b1df8-e563-4996-88f9-d2b3d313edc1 ER - TY - JOUR TI - Influence of cooling rates on microstructure and mechanical performance of continuous fiber reinforced PPS composites AU - Trudel-Boucher, David AU - Esquirol, A.-L. AU - Bureau, Martin N. T2 - SAMPE International Symposium and Exhibition - Emerging Opportunities : Materials and Process Solutions T3 - Society for the Advancement of Material and Process Engineering International Symposium and Exhibition 2012 (SAMPE 2012), 21-24 May 2012, Baltimore, Maryland, USA SN - 9781934551127 AB - In this study, the influence of the cooling rate on the crystallization temperature, level of crystallinity, spherulite size and mechanical properties was investigated for two continuous fibers reinforced polyphenylene sulfide (PPS) composites. Crystallization temperature and level of crystallinity were first studied by differential scanning calorimetry (DSC) for cooling rates comprised between 5 and 70°C/min. Results obtained showed that level of crystallinity was not significantly influenced by the cooling rate, while crystallization temperature decreased with increasing cooling rate. Matrix microstructure and composite short beam shear strength were then characterized for cooling rates of 3, 15 and 20°C/min. These cooling rates were chosen because they are representative of cooling rates used in autoclave manufacturing and compression molding. To enhance the microstructure of the PPS matrix, an etching solution based on potassium permanganate and orthophosphoric acid was used. DA - 2012/05/24 PY - 2012 PB - Society for the Advancement of Material and Process Engineering LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5aed46d7-c539-4ee5-8ca9-ab6f909b2c27 ER - TY - JOUR TI - Engineering HVOF-Sprayed Cr3C2-NiCr coatings : the effect of particle morphology and spraying parameters on the microstructure, properties and high temperature wear performance AU - Poirier, D. AU - Legoux, J.-G. AU - Lima, R. S. T2 - Thermal Spray 2012: Proceedings of the International Thermal Spray Conference T3 - International Thermal Spray Conference 2012 (ITSC 2012), 21-24 May 2012, Houston, Texas, USA SP - 22 EP - 27 AB - Chromium carbide-based thermally sprayed coatings are widely used for high temperature wear applications. In these extreme environments at those temperatures, several phenomena will degrade, oxidize and change the microstructure of the coatings, thereby affecting their wear behaviour. Although it can be easily conceived that the Cr3C2-NiCr coating microstructure evolution after high temperature exposure will depend on the as-sprayed microstructure and spraying parameters, very little has been done in this regard. This study intends to develop a better understanding of the effect of spraying parameters on the resulting chromium carbide coating microstructure after high temperature operation and high temperature sliding wear properties. The microstructures of different coatings produced from two morphologies of Cr3C2-NiCr powders and under a window of in-flight particle temperature and velocity values were characterized through X-ray diffraction (XRD) and scanning electron microscopy (SEM). Sliding wear at 800°C was performed and the wear behaviour correlated to the spraying parameters and coating microstructure. Vickers microhardness (300 gf) of the coatings before and after sliding wear was also measured. DA - 2012/05/21 PY - 2012 UR - http://www.asminternational.org/portal/site/www/AsmStore/ProductDetails/?vgnextoid=0479be8b96d37310VgnVCM100000621e010aRCRD#details LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 34e6d855-5107-4c22-a5b3-b36ecd204961 ER - TY - JOUR TI - Metabolism and metabonomics in cancer risk Assessment, diagnosis, prognosis and treatment DO - 10.4172/jmbm.1000e108 AU - Cuperlovic-Culf, M. T2 - Journal of Metabonomics & Metabolites SN - 2325-9736 VL - 1 IS - 2 DA - 2012/11/19 PY - 2012 PB - SciTechnol LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b0e552f3-a614-4249-b715-00281d1dba85 ER - TY - JOUR TI - Learning machine translation from in-domain and out-of-domain data AU - Turchi, Marco AU - Goutte, Cyril AU - Cristianini, Nello T2 - Proceedings of the 16th Annual Conference of the European Association for Machine Translation T3 - 16th Annual Conference of the European Association for Machine Translation (EAMT), 28-30 May 2012, Trento, Italy SP - 305 EP - 312 AB - The performance of Phrase-Based Statistical Machine Translation (PBSMT) systems mostly depends on training data. Many papers have investigated how to create new resources in order to increase the size of the training corpus in an attempt to improve PBSMT performance. In this work, we analyse and characterize the way in which the in-domain and outof- domain performance of PBSMT is impacted when the amount of training data increases. Two different PBSMT systems, Moses and Portage, two of the largest parallel corpora, Giga (French-English) and UN (Chinese-English) datasets and several in- and out-of-domain test sets were used to build high quality learning curves showing consistent logarithmic growth in performance. These results are stable across language pairs, PBSMT systems and domains. We also analyse the respective impact of additional training data for estimating the language and translation models. Our proposed model approximates learning curves very well and indicates the translation model contributes about 30% more to the performance gain than the language model. DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b9e5bc8b-b13a-4964-96b6-ac4a29c17a65 ER - TY - JOUR TI - The impact of sentence alignment errors on phrase-based machine translation performance AU - Goutte, Cyril AU - Carpuat, Marine AU - Foster, George T2 - Proceedings of the Tenth Conference of the Association for Machine Translation in the Americas T3 - The Tenth Biennial Conference of the Association for Machine Translation in the Americas, 28 October-1 November 2012, San Diego, California, USA AB - When parallel or comparable corpora are harvested from the web, there is typically a tradeoff between the size and quality of the data. In order to improve quality, corpus collection efforts often attempt to fix or remove misaligned sentence pairs. But, at the same time, Statistical Machine Translation (SMT) systems are widely assumed to be relatively robust to sentence alignment errors. However, there is little empirical evidence to support and characterize this robustness. This contribution investigates the impact of sentence alignment errors on a typical phrase-based SMT system. We confirm that SMT systems are highly tolerant to noise, and that performance only degrades seriously at very high noise levels. Our findings suggest that when collecting larger, noisy parallel data for training phrase-based SMT, cleaning up by trying to detect and remove incorrect alignments can actually degrade performance. Although fixing errors, when applicable, is a preferable strategy to removal, its benefits only become apparent for fairly high misalignment rates. We provide several explanations to support these findings. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6aeda7ee-6f72-466f-9c7a-56c71e481d52 ER - TY - JOUR TI - A poor man’s translation memory using machine translation evaluation metrics AU - Simard, Michel AU - Fujita, Atsushi T2 - Proceedings of the Tenth Conference of the Association for Machine Translation in the Americas T3 - The Tenth Biennial Conference of the Association for Machine Translation in the Americas, 28 October-1 November 2012, San Diego, California, USA AB - We propose straightforward implementations of translation memory (TM) functionality for research purposes, using machine translation evaluation metrics as similarity functions. Experiments under various conditions demonstrate the effectiveness of the approach, but also highlight problems in evaluating the results using an MT evaluation methodology. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bcff7104-cfbc-4372-800b-d5b77c040066 ER - TY - JOUR TI - Fast and efficient face recognition system using Random Forest and Histograms of Oriented Gradients AU - Salhi, Abdel Ilah AU - Kardouchi, Mustapha AU - Belacel, Nabil T2 - Proceedings of the International Conference of the Biometrics Special Interest Group (BIOSIG) T3 - 2012 International Conference of the Biometrics Special Interest Group (BIOSIG), 6-7 September 2012, Darmstadt, Germany SN - 978-1-4673-1010-9 SP - 1 EP - 12 AB - The efficient face recognition systems are those which are able to achieve higher recognition rate with lower computational cost. To develop such systems both feature representation and classification method should be accurate and less time consuming.Aiming to satisfy these criteria we coupled the HOG descriptor (Histograms of Oriented Gradients) with the Random Forest classifier (RF). Although rarely used in face recognition, HOG have proven to be a power descriptor in this task with a lower computational time. As regards classification method, recent works have shown that apart from their accuracy when compared with its competitors, Random Forest exhibits a low computational time in both training and testing phase. Experimental results on ORL database have demonstrated the efficiency of this combination. DA - 2012/09 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d7f33e83-d1a5-4a34-b194-614aee4a4f9e ER - TY - JOUR TI - Learning to translate : a statistical and computational analysis DO - 10.1155/2012/484580 AU - Turchi, Marco AU - De Bie, Tijl AU - Goutte, Cyril AU - Cristianini, Nello T2 - Advances in Artificial Intelligence VL - 2012 SP - 484580 SP - 1 EP - 15 AB - We present an extensive experimental study of Phrase-based Statistical Machine Translation, from the point of view of its learning capabilities. Very accurate Learning Curves are obtained, using high-performance computing, and extrapolations of the projected performance of the system under different conditions are provided. Our experiments confirm existing and mostly unpublished beliefs about the learning capabilities of statistical machine translation systems. We also provide insight into the way statistical machine translation learns from data, including the respective influence of translation and language models, the impact of phrase length on performance, and various unlearning and perturbation analyses. Our results support and illustrate the fact that performance improves by a constant amount for each doubling of the data, across different language pairs, and different systems. This fundamental limitation seems to be a direct consequence of Zipf law governing textual data. Although the rate of improvement may depend on both the data and the estimation method, it is unlikely that the general shape of the learning curve will change without major changes in the modeling and inference phases. Possible research directions that address this issue include the integration of linguistic rules or the development of active learning procedures. DA - 2012/02 PY - 2012 PB - Hindawi LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fb92f18a-a6da-4cae-b18d-a8e9e3f25dda ER - TY - JOUR TI - Real-time blood circulation and bleeding model for surgical training DO - 10.1109/TBME.2012.2230326 AU - Boisvert, Jonathan AU - Poirier, Guillaume AU - Borgeat, Louis AU - Godin, Guy T2 - IEEE Transactions on Biomedical Engineering SN - 0018-9294 VL - 60 IS - 4 SP - 1013 EP - 1022 KW - fluid flow; hemostasis; medical simulation; personalized modelling; surgery; vascular model AB - Intraoperative management of bleeding is a critical skill all surgeons must possess. It is, however, very challenging to create a safe and realistic learning environment for its acquisition. In this paper, we propose a simple and efficient approach to integrate blood circulation to computerized surgical simulation systems and allow for real-time processing of punctures, ruptures, and cauterization of blood vessels. Blood pressures and flows are calculated using a system of ordinary differential equations, which can be simulated very efficiently. The equation system itself is constructed using a graph of the vessels’ connectivity extracted from magnetic resonance angiograms (MRA) and completed with virtual vessels deduced from the principle of minimum work. Realtime performances of the method are assessed and results are demonstrated on ten patients who underwent a MRA before removal of a brain tumor. DA - 2012/11/29 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3632eb13-17ad-42fd-9e90-1e9892e0b07c ER - TY - JOUR TI - Communication : the structures of small cationic gas-phase platinum clusters DO - 10.1063/1.4726403 AU - Harding, Dan J. AU - Kerpal, Christian AU - Rayner, David M. AU - Fielicke, André T2 - Journal of Chemical Physics SN - 0021-9606 VL - 136 IS - 21 SP - 211103-1 EP - 211103-4 AB - The structures of small platinum clusters Pt 3−5+ are determined using far-infrared multiple photon dissociation spectroscopy of their argon complexes combined with density functional theory calculations. The clusters are found to have compact structures, and Pt 4+ and Pt 5+ already favor three-dimensional geometries, in contrast to a number of earlier predictions. Challenges in applying density functional theory to 3rd row transition metal clusters are addressed. Preliminary calculations suggest that the effects of spin-orbit coupling do not change the favoured lowest-energy isomers DA - 2012/06/04 PY - 2012 PB - American Institute of Physics LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fe841a82-a454-4351-9075-7a5ba5e36129 ER - TY - JOUR TI - Coulomb asymmetry and sub-cycle electron dynamics in multiphoton multiple ionization of H2 DO - 10.1088/0953-4075/45/19/194011 AU - Spanner, M. AU - Grafe, S. AU - Chelkowski, S. AU - Pavicic, D. AU - Meckel, M. AU - Zeidler, D. AU - Bardon, A. B. AU - Ulrich, B. AU - Bandrauk, A. D. AU - Villeneuve, D. M. AU - Dorner, R. AU - Corkum, P. B. AU - Staudte, A. T2 - Journal of Physics B : Atomic, Molecular and Optical Physics SN - 0953-4075 VL - 45 IS - 19 SP - 194011 SP - 1 EP - 10 AB - We present a systematic study of the molecular-frame photo-electron angular distributions produced by multiphoton double ionization of H2 using circularly polarized 800 nm, femtosecond laser pulses. We compare experimental results to numerical results obtained from a reduced-dimensionality time-dependent Schr¨odinger equation (TDSE) model. In addition, we implement a TDSE-like version of the strong-field approximation to isolate the effect of the parent ion’s Coulomb potential on the continuum electron in our simulations. Thereby we identify the contributions of the parent ion potential, and light induced sub-optical cycle electron dynamics on the observable energy and angular distributions. DA - 2012/09/24 PY - 2012 PB - IOP Publishing LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a3f57817-e9d8-4cc0-ab1b-22704a100a3a ER - TY - JOUR TI - Observation of Cooper minimum in krypton using high harmonic spectroscopy DO - 10.1088/0953-4075/45/7/074010 AU - Shiner, A. D. AU - Schmidt, B. E. AU - Trallero-Herrero, C. AU - Corkum, P. B. AU - Kieffer, J-C. AU - Légaré, F. AU - Villeneuve, D. M. T2 - Journal of Physics B : Atomic, Molecular and Optical Physics SN - 0953-4075 VL - 45 IS - 7 SP - 1 EP - 4 AB - High harmonic spectroscopy utilizes the methods of attosecond science to study electronic properties of atoms and molecules. We use a 1.8 μm 11 fs laser source to generate high harmonic spectra beyond 150 eV. The Cooper minimum in krypton is clearly visible in these spectra, and would otherwise be difficult to observe with 800 nm laser sources. We relate the shape of the spectrum to the photoionization cross section of krypton. DA - 2012/03/16 PY - 2012 PB - IOP Publishing LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b272d076-8c40-443d-8737-79d58bc51e36 ER - TY - JOUR TI - High harmonic generation with long-wavelength few-cycle laser pulses DO - 10.1088/0953-4075/45/7/074008 AU - Schmidt, Bruno E. AU - Shiner, Andrew D. AU - Giguère, Mathieu AU - Lassonde, Philippe AU - Trallero-Herrero, Carlos A. AU - Kieffer, J-C. AU - Corkum, P. B. AU - Villeneuve, D. M. AU - Légaré, Francois T2 - Journal of Physics B : Atomic, Molecular and Optical Physics SN - 0953-4075 VL - 45 IS - 7 SP - 074008 SP - 1 EP - 9 AB - We report the extension of hollow-core fibre pulse compression to longer wavelengths. High-energy multi-cycle infrared pulses are generated via optical parametric amplification and subsequently broadened in the fibre. 2.5-cycle pulses at the Signal wavelength (1.4 µm) and 1.6-cycle pulses at the Idler wavelength (1.8 µm) in the sub-millijoule regime have been generated. New compression schemes can be applied at 1.8 µm and beyond. In this manner, 1.6-cycle carrier envelope phase stable pulses were generated by linear propagation in the anomalous dispersion regime of bulk glass which surprisingly enables compression below its third-order dispersion limit. Furthermore, a dispersion-free way of controlling the carrier envelope phase is demonstrated. Moreover, we experimentally confirm the increase in high-harmonic cut-off energy with driving laser wavelength and demonstrate the beneficial effect of few-cycle pulses which enable higher saturation intensities on target compared to multi-cycle pulses. It will be an ideal tool for future synthesis of isolated attosecond pulses in the sub-keV regime. With this laser source, we revealed for the first time multi-electron effects in high harmonic generation in xenon. DA - 2012/03/16 PY - 2012 PB - IOP Publishing LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d64b383a-0685-47b4-91a1-79bd6b94d3e6 ER - TY - JOUR TI - All-optical measurement of high-harmonic amplitudes and phases in aligned molecules DO - 10.1103/PhysRevLett.108.033903 AU - Rupenyan, A. AU - Bertrand, J. B. AU - Villeneuve, D. M. AU - Worner, H. J. T2 - Physical Review Letters VL - 108 IS - 3 SP - 033903-1 EP - 033903-5 AB - We report a new all-optical approach to measuring the phase and amplitude of high-harmonic emission from aligned molecules. We combine the transient grating technique with a continuous rotation of the molecular alignment axis and develop an analytical model that enables the simultaneous determination of phases and amplitudes. Measurements in N2 molecules are shown to be in qualitative agreement with the results of ab initio quantum scattering calculations. DA - 2012/01/20 PY - 2012 PB - American Physical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 46a9bdd8-9876-4d91-8413-0c81262b4dd5 ER - TY - JOUR TI - High-harmonic transient grating spectroscopy of NO2 electronic relaxation DO - 10.1063/1.4768810 AU - Ruf, H. AU - Handschin, C. AU - Ferré, A. AU - Thiré, N. AU - Bertrand, J. B. AU - Bonnet, L. AU - Cireasa, R. AU - Constant, E. AU - Corkum, P. B. AU - Descamps, D. AU - Fabre, B. AU - Larregaray, P. AU - Mével, E. AU - Petit, S. AU - Pons, B. AU - Staedter, D. AU - Worner, H. J. AU - Villeneuve, D. M. AU - Mairesse, Y. AU - Halvick, P. AU - Blanchet, V. T2 - The Journal of Chemical Physics VL - 137 IS - 22 SP - 224303-1 EP - 224303-10 AB - We study theoretically and experimentally the electronic relaxation of NO2 molecules excited by absorption of one ∼400 nm pump photon. Semiclassical simulations based on trajectory surface hopping calculations are performed. They predict fast oscillations of the electronic character around the intersection of the ground and first excited diabatic states. An experiment based on high-order harmonic transient grating spectroscopy reveals dynamics occurring on the same time scale. A systematic study of the detected transient is conducted to investigate the possible influence of the pump intensity, pump wavelength, and rotational temperature of the molecules. The quantitative agreement between measured and predicted dynamics shows that, in NO2, high harmonic transient grating spectroscopy encodes vibrational dynamics underlying the electronic relaxation. DA - 2012/12/11 PY - 2012 PB - American Institute of Physics LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 79ff2dae-f2b7-419f-a669-c57c323911ab ER - TY - JOUR TI - Frequency-resolved optical gating for time-resolving knockout in double ionization with attosecond pulses DO - 10.1103/PhysRevA.86.053411 AU - Price, H. AU - Staudte, A. AU - Corkum, P. B. AU - Emmanouilidou, A. T2 - Physical Review A VL - 86 IS - 5 SP - 053411-1 EP - 053411-5 AB - We develop the two-electron attosecond streak camera under realistic conditions using a quasiclassical model. We assume extreme ultraviolet (XUV) attosecond pulses with a full width at half maximum (FWHM) of 24 attoseconds, centered at 120 eV and a streaking infrared laser field of 1600 nm, and intensity of 1.8 × 1012 W/cm2. The proposed method is shown to be capable of time resolving two-electron collisions in double ionization. DA - 2012/11/16 PY - 2012 PB - American Physical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4e180b5f-90d0-4110-b5f2-48245a554529 ER - TY - JOUR TI - High-pressure gas phase femtosecond laser ionization mass spectrometry DO - 10.1021/ac300743k AU - Peng, Jiahui AU - Puskas, Noah AU - Corkum, Paul B. AU - Rayner, David M. AU - Loboda, Alexandre V. T2 - Analytical Chemistry VL - 84 IS - 13 SP - 5633 EP - 5640 AB - We describe a novel ion source for analytical mass spectrometry based on femtosecond laser ionization at pressures at and above atmospheric and characterize its performance when coupled to a tandem quadrupole/time-of-flight mass spectrometer. We assess source saturation limits, ionization and sampling efficiencies, the effective ionization volume, and limits of detection. We demonstrate 100% efficient ionization for a set of organic compounds and show that the degree of ion fragmentation over a range of laser powers is favorable compared to electron impact ionization, especially in that a substantial parent ion signal is always observed. We show how collisional cooling plays a role in controlling fragmentation at high pressures and address how ion–molecule chemistry can be controlled or exploited. High-pressure femtosecond laser ionization will allow “universal” and efficient ionization, presenting a research direction that will broaden the options for gas phase analysis beyond the capabilities of electron impact ionization. DA - 2012/05/30 PY - 2012 PB - American Chemical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8c0691b7-362f-4e8b-bc8f-39e7fc7b6c62 ER - TY - JOUR TI - Time-resolved high-harmonic spectroscopy of nonadiabatic dynamics in NO2 DO - 10.1103/PhysRevA.85.043409 AU - Kraus, P. M. AU - Arasaki, Y. AU - Bertrand, J. B. AU - Patchkovskii, S. AU - Corkum, P. B. AU - Villeneuve, D. M. AU - Takatsuka, K. AU - Worner, H. J. T2 - Physical Review A VL - 85 IS - 4 SP - 043409-1 EP - 043409-5 AB - Time-resolved high-harmonic spectroscopy is an emerging approach to measuring coupled electronic and nuclear dynamics in photochemical reactions. A general conceptual and theoretical model for the technique is derived from first principles and applied to study the sensitivity of the technique to nonadiabatic dynamics. By comparing the model with detailed experimental data on photoexcited NO2 molecules, we find that time-resolved high-harmonic spectroscopy is primarily sensitive to electronic population dynamics. The coordinate dependence of the vertical ionization potential and photorecombination matrix elements contribute also, but much less significantly, to the observed dynamics because of the rapid spreading of the wave packet in the excited state. We discuss the extension of the method to larger polyatomic molecules in light of this insight. DA - 2012/04/12 PY - 2012 PB - American Physical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0cd9156b-02e5-4bb9-a610-76919eee7ee3 ER - TY - JOUR TI - Intensity dependence of multiple orbital contributions and shape resonance in high-order harmonic generation of aligned N2 molecules DO - 10.1103/PhysRevA.85.013405 AU - Jin, Cheng AU - Bertrand, Julien B. AU - Lucchese, R. R. AU - Worner, H. J. AU - Corkum, Paul B. AU - Villeneuve, D. M. AU - Le, Anh-Thu AU - Lin, C. D. T2 - Physical Review A VL - 85 IS - 1 SP - 013405-1 EP - 013405-7 AB - We report measurements and theoretical simulations of high-order harmonic generation (HHG) in aligned N2 molecules using a 1200-nm intense laser field when the generating pulse is perpendicular to the aligning one. With increasing laser intensity, the minimum in the HHG spectra first shifts its position and then disappears. Theoretical simulations including the macroscopic propagation effects in the medium reproduce these observations and the disappearance of the minimum is attributed to the additional contribution of HHG from inner orbitals. We also predict that the well-known shape resonance in the photoionization spectra of N2 should exist in the HHG spectra. It is most clearly seen when the generating laser is parallel to the aligning one and disappears gradually as the angle between the two lasers increases. No clear evidence of this shape resonance has been reported so far when using lasers with different wavelengths. Further experimentation is needed to draw conclusions. DA - 2012/01/09 PY - 2012 PB - American Physical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 290c1a0a-a5ec-43b3-8166-a3adc3478342 ER - TY - JOUR TI - Oriented rotational wave-packet dynamics studies via high harmonic generation DO - 10.1103/PhysRevLett.109.113901 AU - Frumker, E. AU - Hebeisen, C. T. AU - Kajumba, N. AU - Bertrand, J. B. AU - Worner, H. J. AU - Spanner, M. AU - Villeneuve, D. M. AU - Naumov, A. AU - Corkum, P. B. T2 - Physical Review Letters VL - 109 IS - 11 SP - 113901-1 EP - 113901-5 AB - We produce oriented rotational wave packets in CO and measure their characteristics via high harmonic generation. The wave packet is created using an intense, femtosecond laser pulse and its second harmonic. A delayed 800 nm pulse probes the wave packet, generating even-order high harmonics that arise from the broken symmetry induced by the orientation dynamics. The even-order harmonic radiation that we measure appears on a zero background, enabling us to accurately follow the temporal evolution of the wave packet. Our measurements reveal that, for the conditions optimum for harmonic generation, the orientation is produced by preferential ionization which depletes the sample of molecules of one orientation. DA - 2012/09/12 PY - 2012 PB - American Physical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f67ef34b-12f0-4c85-ace1-d4f9851dec02 ER - TY - JOUR TI - Order-dependent structure of high harmonic wavefronts DO - 10.1364/OE.20.013870 AU - Frumker, E. AU - Paulus, G. G. AU - Niikura, H. AU - Naumov, A. AU - Villeneuve, D. M. AU - Corkum, P. B. T2 - Optics Express VL - 20 IS - 13 SP - 13870 EP - 13877 AB - The physics of high harmonics has led to the generation of attosecond pulses and to trains of attosecond pulses. Measurements that confirm the pulse duration are all performed in the far field. All pulse duration measurements tacitly assume that both the beam’s wavefront and intensity profile are independent of frequency. However, if one or both are frequency dependent, then the retrieved pulse duration depends on the location where the measurement is made. We measure that each harmonic is very close to a Gaussian, but we also find that both the intensity profile and the beam wavefront depend significantly on the harmonic order. Thus, our findings mean that the pulse duration will depend on where the pulse is observed. Measurement of spectrally resolved wavefronts along with temporal characterization at one single point in the beam would enable complete space-time reconstruction of attosecond pulses. Future attosecond science experiments need not be restricted to spatially averaged observables. Our approach paves the way to recovery of the single molecule response to the strong field. DA - 2012/06/07 PY - 2012 PB - Optical Society of America LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8013218b-e332-456e-ba51-cd6e8c82e899 ER - TY - JOUR TI - Probing polar molecules with high harmonic spectroscopy DO - 10.1103/PhysRevLett.109.233904 AU - Frumker, E. AU - Kajumba, N. AU - Bertrand, J. B. AU - Worner, H. J. AU - Hebeisen, C. T. AU - Hockett, P. AU - Spanner, M. AU - Patchkowskii, S. AU - Paulus, G. G. AU - Villeneuve, D. M. AU - Naumov, A. AU - Corkum, P. B. T2 - Physical Review Letters VL - 109 IS - 23 SP - 233904-1 EP - 233904-5 AB - We bring the methodology of orienting polar molecules together with the phase sensitivity of high harmonic spectroscopy to experimentally compare the phase difference of attosecond bursts of radiation emitted upon electron recollision from different ends of a polar molecule. This phase difference has an impact on harmonics from aligned polar molecules, suppressing emission from the molecules parallel to the driving laser field while favoring the perpendicular ones. For oriented molecules, we measure the amplitude ratio of even to odd harmonics produced when intense light irradiates CO molecules and determine the degree of orientation and the phase difference of attosecond bursts using molecular frame ionization and recombination amplitudes. The sensitivity of the high harmonic spectrum to subtle phase differences in the emitted radiation makes it a detailed probe of polar molecules and will drive major advances in the theory of high harmonic generation. DA - 2012/12/04 PY - 2012 PB - American Physical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3f357cf5-a7e9-4e67-9ff0-22b82dffa6d5 ER - TY - JOUR TI - Routes to formation of highly excited neutral atoms in the breakup of strongly driven H2 DO - 10.1103/PhysRevA.85.011402 AU - Emmanouilidou, A. AU - Lazarou, C. AU - Staudte, A. AU - Eichmann, U. T2 - Physical Review VL - 85 IS - 1 SP - 011402-1 EP - 011402-4 AB - We present a theoretical quasiclassical treatment of the formation, during Coulomb explosion, of highly excited neutral H atoms (H∗) for strongly driven H2. This process, where after the laser field is turned off, one electron escapes to the continuum while the other occupies a Rydberg state, was recently reported in an experimental study [B. Manschwetus et al., Phys. Rev. Lett. 102, 113002 (2009)]. We find that two-electron effects are important in order to correctly account for all pathways leading to H∗ formation.We identify two pathways where the electron that escapes to the continuum does so either very quickly or after remaining bound for a few periods of the laser field. These two pathways of H∗ formation have distinct traces in the probability distribution of the escaping electron momentum components. DA - 2012/01/11 PY - 2012 PB - American Physical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e17bd3e0-3200-43fb-9ee2-f71c115e330f ER - TY - JOUR TI - Revealing the cooper minimum of N2 by molecular frame high-harmonic spectroscopy DO - 10.1103/PhysRevLett.109.143001 AU - Bertrand, J. B. AU - Wörner, H. J. AU - Hockett, P. AU - Villeneuve, D. M. AU - Corkum, P. B. T2 - Physical Review Letters SN - 0031-9007 VL - 109 IS - 14 SP - 143001-1 EP - 143001-5 AB - Molecular frame high-harmonic spectra of aligned N2 molecules reveal a Cooper-like minimum. By deconvolving the laboratory frame alignment distribution, what was previously thought to be a maximum of emission along the molecular axis is found to be maxima at 35 degrees off axis, with a spectral minimum on axis. Both of these features are supported by photoionization calculations that underline the relationship between high-harmonic spectroscopy and photoionization measurements. The calculations reveal that the on axis spectral minimum is a Cooper-like minimum that arises from the destructive interference of the p and f partial wave contributions to high-harmonic photorecombination. Features such as Cooper minima and shape resonances are ubiquitous in molecular photoionization or recombination. DA - 2012/10/04 PY - 2012 PB - American Physical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 14896c42-e24f-4d74-8971-968ba0b43b96 ER - TY - CHAP TI - InAs quantum dots of engineered height for fabrication of broadband superluminescent diodes DO - 10.5772/34209 AU - Haffouz, S. AU - Barrios, P. J. AU - Al-Ahmadi, Ameenah T2 - Fingerprints in the Optical and Transport Properties of Quantum Dots SN - 978-953-51-0648-7 SP - 1 EP - 26 DA - 2012/06/13 PY - 2012 PB - InTech LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 268d3dd4-7b53-488d-84cd-d62f927034b8 ER - TY - JOUR TI - Tunable terahertz beat signal generation from an InAs/InP quantum-dot mode-locked laser combined with external-cavity DO - 10.1109/LPT.2011.2182642 AU - Jiao, Zhejing AU - Liu, Jiaren AU - Lu, Zhenguo AU - Zhang, Xiupu AU - Poole, Philip J. AU - Barrios, Pedro J. AU - Poitras, Daniel AU - Caballero, Juan T2 - Photonics Technology Letters, IEEE SN - 1041-1135 VL - 24 IS - 6 SP - 518 EP - 520 KW - Fiber Bragg gratings (FBGs); quantum-dot mode-locked lasers (QD MLLs); terahertz beat signal AB - Tunable terahertz beat signal generation is demonstrated by using a C-band InAs/InP quantum-dot (QD) mode-locked laser combined with external cavity of two fiber Bragg gratings (FBGs), where one of the FBGs is tunable in wavelength. Beat signals with ultra-high repetition rates quasi-continuously from 1 to 2.21 THz are observed between the two modes, which are phase-correlated due to intracavity four-wave mixing effect in the QD waveguide. DA - 2012/01/03 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fc31a188-53c0-4a98-ac2f-2525e9ee1dd8 ER - TY - JOUR TI - High-resolution methane spectroscopy using InGaAsSb/AlInGaAsSb laterally-coupled index-grating distributed feedback laser diode at 3.23 μm DO - 10.1049/el.2012.0109 AU - Gupta, J. A. AU - Bezinger, A. AU - Barrios, P. J. AU - Lapointe, J. AU - Poitras, D. AU - Waldron, P. T2 - Electronics Letters SN - 0013-5194 VL - 48 IS - 7 SP - 396 EP - 397 AB - A lateral etched-grating process was used to produce singlemode distributed feedback laser diodes at 3.23 μm. The devices are based on InGaAsSb/AlInGaAsSb type-I quantum well active regions grown on GaSb substrates by molecular beam epitaxy. The lasers were used in high-resolution spectroscopy of methane gas near the v3, R7 vibrational absorption transitions. DA - 2012/03/29 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : aab00c4f-9896-44f3-bfd2-1ef8ef432c0b ER - TY - JOUR TI - Linewidth enhancement factor of InAs/InP quantum dot lasers around 1.5 μm DO - 10.1016/j.optcom.2012.07.002 AU - Jiao, Z. J. AU - Lu, Z. G. AU - Liu, J. R. AU - Poole, P. J. AU - Barrios, P. J. AU - Poitras, D. AU - Pakulski, G. AU - Caballero, J. AU - Zhang, X. P. T2 - Optics Communications SN - 0030-4018 VL - 285 IS - 21-22 SP - 4372 EP - 4375 KW - InAs/InP quantum dot lasers; linewidth enhancement factor; injection locking technique; Hakki–Paoli method AB - Linewidth enhancement factor (LEF) of InAs/InP quantum dot (QD) multi-wavelength lasers (MWLs) emitting around 1.5 μm is investigated both above and below the threshold. Above the threshold, LEFs at three different wavelengths around the gain peak of 1.53 μm by the injection locking technique are obtained to be 1.63, 1.37 and 1.59. Then by Hakki–Paoli method LEF is found to decrease with increased current and shows a value of less than 1 below the threshold. These small LEF values have clearly indicated that our developed InAs/InP QDs are perfect and promising gain materials for QD MWLs, QD mode-locked lasers (QD MLLs) and QD distributed-feedback (QD DFB) lasers around 1.5 μm. DA - 2012/07/17 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e424ba2f-a8cf-4a98-8a66-be51cf427f59 ER - TY - JOUR TI - Grain size, texture, and crystallinity in lanthanum monosulfide thin films grown by pulsed laser deposition DO - 10.1016/j.tsf.2012.10.022 AU - Fairchild, S. AU - Cahay, M. AU - Murray, P. T. AU - Grazulis, L. AU - Wu, X. AU - Poitras, D. AU - Lockwood, D. J. T2 - Thin Solid Films SN - 0040-6090 VL - 524 SP - 166 EP - 172 KW - pulsed laser deposition; X-ray diffraction; transmission electron microscopy; atomic force microscopy; Raman spectroscopy AB - We report a detailed investigation of the growth of lanthanum monosulfide (LaS) thin films by pulsed laser deposition on (001) magnesium oxide (MgO) substrates in a background of H2S for the purpose of optimizing their crystallinity, texture, and grain size. A variety of films were grown while varying the laser repetition rate, the temperature of the substrate, and the partial pressure of H2S. The thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), Raman spectroscopy, and high resolution transmission electron microscopy. Films grown at 500 °C with a H2S background pressure of 3.4 × 10− 4 Pa and a laser repetition rate of 8 Hz produced the LaS film with the largest grains whose size averaged 293 nm. The XRD pattern of these films revealed that their orientation was predominantly (200). AFM images of the surface of these films showed large plate-like grains. This contrasts with the fine grain structure observed in LaS films grown at a lower substrate temperature and lower H2S pressure. DA - 2012/10/22 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 970705c3-868a-4a63-a85a-c28b915428f2 ER - TY - JOUR TI - Near-infrared ultrawide bandwidth LEDs using InAs quantum dots of equally tuned heights DO - 10.1109/LPT.2012.2211867 AU - Haffouz, Sofiane AU - Barrios, Pedro J. AU - Poitras, Daniel AU - Normandin, Richard T2 - IEEE Photonics Technology Letters SN - 1041-1135 VL - 24 IS - 19 SP - 1677 EP - 1679 KW - gallium arsenide; indium arsenide; light-emitting diodes (LEDs); molecular beam epitaxy; quantum dots (QDs) AB - Ultrawide bandwidth light-emitting diodes (LEDs) using eight layers of InAs/GaAs quantum dots (QDs) of equally tuned heights are reported. Tilted and tapered waveguides of various dimensions are tested under continuous-wave operation conditions. An emission spectrum with 3-dB bandwidth up to 173 nm at a peak wavelength of 1064.5 nm is achieved. The measured emission spectra of the QDs–LEDs as a function of the injection current indicated that the obtained large bandwidth is related to the contribution of the excited states (p, d) from the ensemble of the dots to the recombination mechanism. Continuous-wave output power of 0.6 mW is measured in the corresponding device that is made of a 1-mm-long waveguide and with tilted and tapered angles of 6° and 2°, respectively. DA - 2012/08/16 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0905c023-8af6-494e-8bb2-fb9d0fa75926 ER - TY - JOUR TI - Structural phase transitions induced by pressure in ammonium borohydride DO - 10.1039/c2cp40160f AU - Flacau, Roxana AU - Yao, Yansun AU - Klug, Dennis D. AU - Desgreniers, Serge AU - Ratcliffe, Christopher I. T2 - Physical Chemistry Chemical Physics VL - 14 IS - 19 SP - 7005 EP - 7011 AB - A combined experimental and theoretical study of hydrogen-rich ammonium borohydride (NH4BH4) subjected to pressures up to 10 GPa indicates two phase transitions, detected by synchrotron radiation powder X-ray diffraction, Raman spectroscopy and Car–Parrinello molecular dynamics calculations, at 1.5 and 3.4 GPa. The ambient pressure, face-centred cubic phase of NH4BH4 transforms into a highly disordered intermediate structure which then evolves upon increasing pressure into an orthorhombic, distorted CsCl structure. The structure of the latter phase was solved using ab initio computational techniques and from a Rietveld full pattern refinement of the powder X-ray diffraction data. DA - 2012/03/29 PY - 2012 PB - RSC Publishing LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ae285c8f-cc47-4f6a-bf68-396a383b6a60 ER - TY - RPRT TI - Overwintering of barges in the Beaufort - assessing ice issues and damage potential DO - 10.4224/21268047 AU - Barker, Anne AU - Timco, Garry T2 - Technical Report KW - Overwinter; Barge; Landfast; Ice; Beafort AB - Overwintering of vessels and barges has been carried out in the Arctic for many years, in the Beaufort as well as in other regions of the Arctic and southern Canada. Draft guidelines from Transport Canada exist for this practice. However, there is uncertainty concerning the damage potential for structures that may be left to freeze-in within the landfast ice region of the Beaufort Sea, particularly those that contain petroleum products. This is a great concern for the Inuvialuit, among others. There is evidence that this freeze-in could be (and has been) done safely but it is not clear how often this has been done or the conditions required to ensure safe overwintering of vessels in the Beaufort Sea. No information exists on the likelihood of damage due to ice or its possible effects. A detailed study focused on the conditions of the Beaufort Sea would greatly aid many stakeholders on the magnitude of this problem and its possible impact. This study brought together different types of relevant data and information to resolve this important issue, with a focus on the ice loading considerations. As such, the objective of this project was to assess the damage potential for vessels or barges overwintering in land-fast ice. The project will inform the Inuvialuit and Regulators on the likelihood of damage and provide information on the best-available means of reducing the likelihood of damage to vessels overwintering in ice in the nearshore region of the Beaufort Sea. The report steps through illustrative scenarios, in order to provide examples of the types of ice loads that could occur in representative overwintering locations. These scenarios lead to the provision of a framework of methods used to evaluate ice loads on vessels. This framework can be applied to assess ice loads on a specific vessel with known structural integrity at a specific location, by a team of qualified operational, ice mechanic and naval architect experts. No design considerations are provided, as that assessment would be too case specific to be of use in an overview of this subject area. The authors conclude that a sheltered spot, with a limited fetch area, to limit pack ice driving forces is a key factor to minimizing the likelihood of damage due to ice. It is not sufficient to say that a vessel will be in landfast ice conditions throughout the winter. There are many locations where a vessel may be in landfast ice conditions for most of the winter, but the vessel may be in dynamic conditions come the spring break-up period. During this period, depending upon the location, ice crushing forces on a vessel and/or ice loads can be sufficient to break mooring lines and potentially damage a vessel. Thus, the overwintering location should have minimal dynamic ice movement in the spring, to avoid this scenario. Finally, in order to partially alleviate concerns about the practice of overwintering, and more specifically, overwintering of fuel barges, the authors recommend that the Inuvialuit Settlement Region implement their own record-keeping of fuel barges that are overwintering. This would take the form of a simple record of location, vessel and contact information. Having a record of overwintering, and a method of tracking it, may help to provide more data on the practice, guidance on best practices related to overwintering (such as notification for affected communities and those travelling in the vicinity of the vessel), and peace of mind in terms of sound site selection practices and monitoring. DA - 2012/08/01 PY - 2012 PB - National Research Council Canada LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 06003e42-c710-45ea-95f9-150cf0d728a7 ER - TY - JOUR TI - Deformation behavior of solid-solution-strengthened Mg-9 wt.% Al alloy subjected to uniaxial tension AU - Lee, S. Y. AU - Gharghouri, M. A. AU - Wang, H. AU - Nayyeri, G. AU - Wu, P. D. AU - Poole, W. J. AU - Wu, W. AU - An, K. T2 - Proceedings of the 9th International Conference on Magnesium Alloys and their Applications (ICMAA12) T3 - Mg2012: 9th International Conference on Magnesium Alloys and their Applications, 8-12 July 2012, Vancouver, Canada SP - 631 EP - 636 KW - magnesium; plastic deformation; neutron diffraction; self-consistent modeling AB - In-situ neutron diffraction has been used to measure lattice strains for different grain orientations as a function of applied stress in a solid-solution-strengthened extruded binary Mg-9wt.%Al alloy. An elastic-viscoplastic self-consistent (EVPSC) model of polycrystal plasticity was used to simulate the macroscopic stress-strain curve and the neutron diffraction data, yielding the relative contributions, critical resolved shear stresses and hardening behavior of the available slip and twinning modes. Non-linear behavior was observed during unloading after deforming the material into the fully plastic regime in tension. The model suggests that this non-linear behavior is mainly due to basal slip. DA - 2012/07/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0730606a-ad78-47d8-861a-ad4fd1bbb0fc ER - TY - JOUR TI - Deformation behaviour of AZ80 subject to multi-axial loading AU - Tomlinson, P. S. AU - Poole, W. J. AU - Sinclair, C. W. AU - Gharghouri, M. A. T2 - Proceedings of the 9th International Conference on Magnesium Alloys and their Applications (ICMAA12) T3 - Mg2012: 9th International Conference on Magnesium Alloys and their Applications, 8-12 July 2012, Vancouver, Canada SP - 789 EP - 794 KW - magnesium; biaxial; deformation; texture; VPSC; model AB - A robust understanding of the deformation behaviour of magnesium alloys under complex loading paths is a prerequisite to the successful fabrication of parts and understanding of their in- service performance. To facilitate this, multi-axial testing has been conducted on thin walled cylindrical samples of cast AZ80 alloy possessing weak initial texture. Internal pressurization, controlled by closed-loop feedback system permits hoop stresses to be created within the sample wall. When generated in conjunction with axial loading this allows a range of biaxial tensile loadings to be induced within the tension-tension quadrant of stress space. In order to facilitate an understanding of the textural evolution of weakly textured AZ80 subjected to these loadings, texture measurements have been conducted on as tested samples via neutron diffraction. This work builds off of prior work which has characterized the behaviour of AZ80 in uniaxial tension and compression and integrates these results. These mechanical testing results have been compared to those predicted by crystal plasticity simulations in order to help understand the deformation behaviour well as texture evolution. DA - 2012/07/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 632fcaab-4d45-4dc8-82ad-e9d1ba283daf ER - TY - JOUR TI - Microstructure development in hypereutectic cast al-si alloys evaluated by metallurgical analysis and neutron diffraction DO - 10.1002/9781118495292.ch218 AU - Kasprzak, W. AU - Sediako, D. AU - Aniolek, M. AU - Kurita, H. T2 - ICAA13: 13th International Conference on Aluminum Alloys T3 - 13th International Conference on Aluminum Alloys (ICAA13), 3-7 June 2012, Pittsburgh, Pennsylvania, USA SN - 9781118458044 SP - 1431 EP - 1440 KW - hypereutectic Al-19%Si alloys; alloying with Cu; Mg; P; microstructure; in-situ neutron diffraction; thermal analysis; hardness; tensile strength DA - 2012/09/04 PY - 2012 PB - Wiley LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0988a9d7-9be2-4286-81b4-23a51285bca0 ER - TY - JOUR TI - Neutron diffraction study on residual stress in aluminum engine blocks following machining and service testing DO - 10.4271/2012-01-0188 AU - Lombardy, Anthony AU - Sediako, Dimitry AU - D'Elia, Francesco AU - Ravindran, C. AU - Mackay, Robert I. T2 - SAE International Journal of Materials and Manufacturing T3 - SAE 2012 World Congress & Exhibition, 24-26 April 2012, Detroit, Michigan, USA VL - 5 IS - 1 SP - 2012-01-0188 SP - 115 EP - 121 AB - Development of lightweight alloys suitable for automobile applications has been of great importance to the automotive industry in recent years. The use of 319 type aluminum alloy in the production of gasoline engine blocks is an example of this shift towards light alloys for large automobile components. However, excessive residual stress along the cylinder bores of these engine blocks may cause problems during engine operation. Therefore, in this study, neutron diffraction was used to evaluate residual stresses along the aluminum cylinder bridge and the gray cast iron liners. The strains were measured in the hoop, radial, and axial orientations, while stresses were subsequently calculated using generalized Hooke’s law. The results suggest that the residual stress magnitude for the aluminum cylinder bridge was tensile for all three measured components and gradually increased with cylinder depth towards the bottom of the cylinder. The residual stress in the gray cast iron liner was highly compressive with a relatively constant stress magnitude. DA - 2012/04/16 PY - 2012 PB - SAE International LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fada8bba-3ad3-4b4e-8e6b-44c3ebeae0d4 ER - TY - JOUR TI - Lipid bilayer – DNA interaction mediated by divalent metal cations : SANS and SAXD study DO - 10.1088/1742-6596/351/1/012011 AU - Uhríková, D. AU - Kučerka, N. AU - Lengyel, A. AU - Pullmannová, P. AU - Teixeira, J. AU - Murugova, T. AU - Funari, S. S. AU - Balgavý, P. T2 - Journal of Physics : Conference Series VL - 351 IS - 1 SP - 012011 SP - 1 EP - 9 AB - The structure of aggregates formed due to DNA interaction with dipalmitoylphosphatidylcholine (DPPC) in presence of Ca2+ and Zn2+ is examined using small-angle synchrotron X-ray diffraction (SAXD) and small-angle neutron scattering (SANS). SAXD detected two structures: LC - condensed lamellar phase and LX - lamellar phase with DNA strands intercalated between the adjacent lipid bilayers, without regular packing at low cation concentration (~1 mM). The high concentration of Zn2+ induces a macroscopic phase separation in mixtures. The SANS curves of DPPC+ions2+ vesicles evaluated using the strip function model have shown different modes of cations binding to the DPPC bilayers. DA - 2012 PY - 2012 PB - IOP Science LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6ed13fbc-d0a4-4610-be4c-ca196d807514 ER - TY - JOUR TI - Interaction of aspirin (Acetylsalicylic Acid) with lipid membranes DO - 10.1371/journal.pone.0034357 AU - Barrett, Matthew A. AU - Zheng, Songbo AU - Roshankar, Golnaz AU - Alsop, Richard J. AU - Belanger, Randy K. R. AU - Huynh, Chris AU - Kučerka, Norbert AU - Rheinstädter, Maikel C. T2 - PLoS ONE VL - 7 IS - 4 SP - e34357 AB - We studied the interaction of Aspirin (acetylsalicylic acid) with lipid membranes using x-ray diffraction for bilayers containing up to 50 mol% of aspirin. From 2D x-ray intensity maps that cover large areas of reciprocal space we determined the position of the ASA molecules in the phospholipid bilayers and the molecular arrangement of the molecules in the plane of the membranes. We present direct experimental evidence that ASA molecules participate in saturated lipid bilayers of DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine)and preferably reside in the head group region of the membrane. Up to 50 mol% ASA molecules can be dissolved in this type of bilayer before the lateral membrane organization is disturbed and the membranes are found to form an ordered, 2D crystal-like structure. Furthermore, ASA and cholesterol were found to co-exist in saturated lipid bilayers, with the ASA molecules residing in the head group region and the cholesterol molecules participating in the hydrophobic membrane core. DA - 2012/04/17 PY - 2012 PB - PLoS LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 89317642-19e5-40c6-95f0-aa01adb5f1de ER - TY - JOUR TI - Molecular structures of fluid phase phosphatidylglycerol bilayers as determined by small angle neutron and X-ray scattering DO - 10.1016/j.bbamem.2012.05.007 AU - Pan, Jianjun AU - Heberle, Frederick A. AU - Tristram-Nagle, Stephanie AU - Szymanski, Michelle AU - Koepfinger, Mary AU - Katsaras, John AU - Kučerka, Norbert T2 - Biochimica et Biophysica Acta (BBA) - Biomembranes SN - 0005-2736 VL - 1818 IS - 9 SP - 2135 EP - 2148 KW - lipid bilayer; bilayer structure; area per lipid; bilayer thickness; molecular dynamics simulations; fluid phase AB - We have determined the molecular structures of commonly used phosphatidylglycerols (PGs) in the commonly accepted biologically relevant fluid phase. This was done by simultaneously analyzing small angle neutron and X-ray scattering data, with the constraint of measured lipid volumes. We report the temperature dependence of bilayer parameters obtained using the one-dimensional scattering density profile model – which was derived from molecular dynamics simulations – including the area per lipid, the overall bilayer thickness, as well as other intrabilayer parameters (e.g., hydrocarbon thickness). Lipid areas are found to be larger than their phosphatidylcholine (PC) counterparts, a result likely due to repulsive electrostatic interactions taking place between the charged PG headgroups even in the presence of sodium counterions. In general, PG and PC bilayers show a similar response to changes in temperature and chain length, but differ in their response to chain unsaturation. For example, compared to PC bilayers, the inclusion of a first double bond in PG lipids results in a smaller incremental change to the area per lipid and bilayer thickness. However, the extrapolated lipid area of saturated PG lipids to infinite chain length is found to be similar to that of PCs, an indication of the glycerol–carbonyl backbone's pivotal role in influencing the lipid–water interface. DA - 2012/05/11 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3172067e-2912-46c2-9172-68a30a3ad85b ER - TY - JOUR TI - Model-based approaches for the determination of lipid bilayer structure from small-angle neutron and X-ray scattering data DO - 10.1007/s00249-012-0817-5 AU - Heberle, Frederick A. AU - Pan, Jianjun AU - Standaert, Robert F. AU - Drazba, Paul AU - Kučerka, Norbert AU - Katsaras, John T2 - European Biophysics Journal SN - 0175-7571 VL - 41 IS - 10 SP - 875 EP - 890 KW - lipid bilayer; bilayer structure; area per lipid; bilayer thickness; molecular dynamics simulations; fluid phase AB - Some of our recent work has resulted in the detailed structures of fully hydrated, fluid phase phosphatidylcholine (PC) and phosphatidylglycerol (PG) bilayers. These structures were obtained from the joint refinement of small-angle neutron and X-ray data using the scattering density profile (SDP) models developed by Kučerka et al. (Biophys J 95:2356–2367, 2008; J Phys Chem B 116:232–239, 2012). In this review, we first discuss models for the standalone analysis of neutron or X-ray scattering data from bilayers, and assess the strengths and weaknesses inherent to these models. In particular, it is recognized that standalone data do not contain enough information to fully resolve the structure of naturally disordered fluid bilayers, and therefore may not provide a robust determination of bilayer structure parameters, including the much-sought-after area per lipid. We then discuss the development of matter density-based models (including the SDP model) that allow for the joint refinement of different contrast neutron and X-ray data, as well as the implementation of local volume conservation within the unit cell (i.e., ideal packing). Such models provide natural definitions of bilayer thicknesses (most importantly the hydrophobic and Luzzati thicknesses) in terms of Gibbs dividing surfaces, and thus allow for the robust determination of lipid areas through equivalent slab relationships between bilayer thickness and lipid volume. In the final section of this review, we discuss some of the significant findings/features pertaining to structures of PC and PG bilayers as determined from SDP model analyses. DA - 2012/05/16 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1e12c51b-2960-4212-9824-d24df0510dd0 ER - TY - JOUR TI - Interactions between ether phospholipids and cholesterol as determined by scattering and molecular dynamics simulations DO - 10.1021/jp310345j AU - Pan, Jianjun AU - Cheng, Xiaolin AU - Heberle, Frederick A. AU - Mostofian, Barmak AU - Kučerka, Norbert AU - Drazba, Paul AU - Katsaras, John T2 - The Journal of Physical Chemistry B VL - 116 IS - 51 SP - 14829 EP - 14838 AB - Cholesterol and ether lipids are ubiquitous in mammalian cell membranes, and their interactions are crucial in ether lipid mediated cholesterol trafficking. We report on cholesterol’s molecular interactions with ether lipids as determined using a combination of small-angle neutron and X-ray scattering, and all-atom molecular dynamics (MD) simulations. A scattering density profile model for an ether lipid bilayer was developed using MD simulations, which was then used to simultaneously fit the different experimental scattering data. From analysis of the data the various bilayer structural parameters were obtained. Surface area constrained MD simulations were also performed to reproduce the experimental data. This iterative analysis approach resulted in good agreement between the experimental and simulated form factors. The molecular interactions taking place between cholesterol and ether lipids were then determined from the validated MD simulations. We found that in ether membranes cholesterol primarily hydrogen bonds with the lipid headgroup phosphate oxygen, while in their ester membrane counterparts cholesterol hydrogen bonds with the backbone ester carbonyls. This different mode of interaction between ether lipids and cholesterol induces cholesterol to reside closer to the bilayer surface, dehydrating the headgroup’s phosphate moiety. Moreover, the three-dimensional lipid chain spatial density distribution around cholesterol indicates anisotropic chain packing, causing cholesterol to tilt. These insights lend a better understanding of ether lipid-mediated cholesterol trafficking and the roles that the different lipid species have in determining the structural and dynamical properties of membrane associated biomolecules. DA - 2012/11/30 PY - 2012 PB - ACS Publications LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1fbb35b3-b862-4a90-b853-5e64582887c1 ER - TY - JOUR TI - Growth kinetics of lipid-based nanodiscs to unilamellar vesicles—A time-resolved small angle neutron scattering (SANS) study DO - 10.1016/j.bbamem.2012.11.002 AU - Mahabir, Suanne AU - Small, Darcy AU - Li, Ming AU - Wan, Wankei AU - Kučerka, Norbert AU - Littrell, Kenneth AU - Katsaras, John AU - Nieh, Mu-Ping T2 - Biochimica et Biophysica Acta (BBA) - Biomembranes SN - 0005-2736 VL - 1828 IS - 3 SP - 1025 EP - 1035 KW - nanodisc; low temperature annealing; unilamellar vesicle; spontaneous formation; self-assemble; reaction limited coalescence AB - Mixtures of dimyristoyl-phosphatidylcholine (DMPC), dimyristoyl-phosphatidylglycerol (DMPG) and dihexanoylphosphatidylcholine (DHPC) in aqueous solutions spontaneously form monodisperse, bilayered nanodiscs (also known as “bicelles”) at or below the melting transition temperature of DMPC (TM ~23 °C). In dilute systems above the main transition temperature TM of DMPC, bicelles coalesce (increasing their diameter) and eventually self-fold into unilamellar vesicles (ULVs). Time-resolved small angle neutron scattering was used to study the growth kinetics of nanodiscs below and equal to TM over a period of hours as a function of temperature at two lipid concentrations in presence or absence of NaCl salt. Bicelles seem to undergo a sudden initial growth phase with increased temperature, which is then followed by a slower reaction-limited growth phase that depends on ionic strength, lipid concentration and temperature. The bicelle interaction energy was derived from the colloidal theory of Derjaguin and Landau, and Verwey and Overbeek (DLVO). While the calculated total energy between discs is attractive and proportional to their growth rate, a more detailed mechanism is proposed to describe the mechanism of disc coalescence. After annealing at low temperature (low-T), samples were heated to 50 °C in order to promote the formation of ULVs. Although the low-T annealing of samples has only a marginal effect on the mean size of end-state ULVs, it does affect their polydispersity, which increases with increased T, presumably driven by the entropy of the system. DA - 2012/11/26 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d613c39a-c346-4c63-a78e-60fbaa8e1026 ER - TY - JOUR TI - Measurement of the residual stress tensor in a compact tension weld specimen DO - 10.1007/s11340-012-9672-7 AU - Traore, Y. AU - Paddea, S. AU - Bouchard, P. J. AU - Gharghouri, M. A. T2 - Experimental Mechanics SN - 0014-4851 VL - 53 IS - 4 SP - 605 EP - 618 KW - full stress tensor; neutron diffraction; slitting; contour method; finite element method AB - Neutron diffraction measurements have been performed to determine the full residual stress tensor along the expected crack path in an austenitic stainless steel (Esshete 1250) compact tension weld specimen. A destructive slitting method was then implemented on the same specimen to measure the stress intensity factor profile associated with the residual stress field as a function of crack length. Finally deformations of the cut surfaces were measured to determine a contour map of the residual stresses in the specimen prior to the cut. The distributions of transverse residual stress measured by the three techniques are in close agreement. A peak tensile stress in excess of 600 MPa was found to be associated with an electron beam weld used to attach an extension piece to the test sample, which had been extracted from a pipe manual metal arc butt weld. The neutron diffraction measurements show that exceptionally high residual stress triaxiality is present at crack depths likely to be used for creep crack growth testing and where a peak stress intensity factor of 35 MPa√m was measured (crack depth of 21 mm). The neutron diffraction measurements identified maximum values of shear stress in the order of 50 MPa and showed that the principal stress directions were aligned to within ~20° of the specimen orthogonal axes. Furthermore it was confirmed that measurement of strains by neutron diffraction in just the three specimen orthogonal directions would have been sufficient to provide a reasonably accurate characterisation of the stress state in welded CT specimens. DA - 2012/09/06 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8be1c17e-513c-4278-8e46-a50aedd625b0 ER - TY - JOUR TI - Orientation dependence of stress distributions in polycrystals deforming elastoplastically under biaxial loadings DO - 10.1016/j.jmps.2012.01.007 AU - Marin, T. AU - Dawson, P. R. AU - Gharghouri, M. A. T2 - Journal of the Mechanics and Physics of Solids SN - 0022-5096 VL - 60 IS - 5 SP - 921 EP - 944 KW - polycrystal plasticity; biaxial loading; neutron diffraction; finite element modeling; austenitic stainless steels AB - The influence of biaxiality of the loading on the crystallographic orientation dependence of crystal stress distributions is examined for polycrystalline solids deformed well into the elastoplastic regime. The examination is couched in terms of two decompositions of the stress. The first is a split of the tensor into its hydrostatic and deviatoric components; the second is a spectral decomposition of the deviatoric stress from which we express the relative values of the principal components as a function of the biaxiality of the stress. Using the framework provided by these decompositions, we investigate trends observed in the lattice strains in polycrystals subjected to biaxial loadings, comparing strains measured by neutron diffraction with finite element simulations. We conclude by showing how the orientation dependence of the stress distributions is influenced by the load biaxiality and by connecting features of the distributions to the elastic and plastic properties of the crystals. Implications of the results are discussed relative to the modeling of strain hardening and defect initiation. DA - 2012/01/10 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7858e020-1855-4603-80db-a36634ea49fe ER - TY - JOUR TI - Neutron diffraction study on residual stress in aluminum engine blocks following machining and service testing DO - 10.4271/2012-01-0188 AU - Lombardy, Anthony AU - Sediako, Dimitry AU - D'Elia, Francesco AU - Ravindran, C. AU - Mackay, Robert I. T2 - SAE International Journal of Materials and Manufacturing VL - 5 IS - 1 SP - 115 EP - 121 AB - Development of lightweight alloys suitable for automobile applications has been of great importance to the automotive industry in recent years. The use of 319 type aluminum alloy in the production of gasoline engine blocks is an example of this shift towards light alloys for large automobile components. However, excessive residual stress along the cylinder bores of these engine blocks may cause problems during engine operation. Therefore, in this study, neutron diffraction was used to evaluate residual stresses along the aluminum cylinder bridge and the gray cast iron liners. The strains were measured in the hoop, radial, and axial orientations, while stresses were subsequently calculated using generalized Hooke's law. The results suggest that the residual stress magnitude for the aluminum cylinder bridge was tensile for all three measured components and gradually increased with cylinder depth towards the bottom of the cylinder. The residual stress in the gray cast iron liner was highly compressive with a relatively constant stress magnitude. DA - 2012/04/16 PY - 2012 PB - SAE International LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6800fcc6-2714-4f41-a222-3b822e2f148d ER - TY - JOUR TI - Interplay between residual stresses, microstructure, process variables and engine block casting integrity DO - 10.1007/s11661-012-1340-0 AU - Lombardi, Anthony AU - D’Elia, Francesco AU - Ravindran, Comondore AU - Sediako, Dimitry AU - Murty, B. S. AU - MacKay, Robert T2 - Metallurgical and Materials Transactions A SN - 1073-5623 VL - 43 IS - 13 SP - 5258 EP - 5270 AB - The replacement of nodular cast iron with 319 type aluminum (Al) alloys in gasoline engine blocks is an example of the shift towards the use of lighter alloys in the automotive industry. However, excessive residual stress along the cylinder bore may lead to bore distortion, significantly reducing engine operating efficiency. In the current study, microstructure, mechanical properties and residual stress were characterized along the cylinder bridge of engine blocks following thermal sand reclamation (TSR), T7 heat treatment, and service testing of the casting. Neutron diffraction was effectively used to quantify the residual stress along both the Al cylinder bridge and the adjacent gray cast iron cylinder liners in the hoop, radial, and axial orientations with respect to the cylinder axis. The results suggest that an increase in cooling rate along the cylinder caused a significant refinement in microstructure at the bottom of the cylinder. In turn, this suggested an increase in alloy strength at the bottom of the cylinder relative to the top. This increased strength at the bottom of the cylinder likely reduced the susceptibility of the cylinder to rapid relief of residual stress at elevated temperature. In contrast, the coarse microstructure at the top of the cylinder likely triggered stress relief at an elevated temperature. DA - 2012/08/16 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e36154ef-9a31-40de-be49-c21f32ffda80 ER - TY - JOUR TI - Patterson analysis for layer profile determination by neutron or X-ray reflectometry DO - 10.1107/S0021889812015075 AU - Tun, Zin T2 - Journal of Applied Crystallography SN - 0021-8898 VL - 45 IS - 3 SP - 398 EP - 405 KW - neutron reflectometry; X-ray reflectometry; layer profile determination; Patterson analysis AB - The possibility of using Patterson analysis to interpret neutron or X-ray reflectometry data has been critically examined in terms of a hypothetical case study. The technique yields a highly accurate layer profile model provided the data are measured with a beam geometry that gives rise to unit reflectivity at Q = 0 only, i.e. Qc = 0. For those cases where a plateau of unit reflectivity extends out to finite Q, i.e. Qc > 0, a distorted model is obtained. A strategy to significantly improve this initial estimate of the model is proposed and demonstrated. DA - 2012/05/04 PY - 2012 PB - Wiley LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1a834bae-f4d6-4009-adf4-de0f72c4d48b ER - TY - JOUR TI - Quantum oscillations of nitrogen atoms in uranium nitride DO - 10.1038/ncomms2117 AU - Aczel, A. A. AU - Granroth, G. E. AU - MacDougall, G. J. AU - Buyers, W. J. L. AU - Abernathy, D. L. AU - Samolyuk, G. D. AU - Stocks, G. M. AU - Nagler, S. E. T2 - Nature Communications VL - 3 SP - 1124 AB - The vibrational excitations of crystalline solids corresponding to acoustic or optic one-phonon modes appear as sharp features in measurements such as neutron spectroscopy. In contrast, many-phonon excitations generally produce a complicated, weak and featureless response. Here we present time-of-flight neutron scattering measurements for the binary solid uranium nitride, showing well-defined, equally spaced, high-energy vibrational modes in addition to the usual phonons. The spectrum is that of a single atom, isotropic quantum harmonic oscillator and characterizes independent motions of light nitrogen atoms, each found in an octahedral cage of heavy uranium atoms. This is an unexpected and beautiful experimental realization of one of the fundamental, exactly solvable problems in quantum mechanics. There are also practical implications, as the oscillator modes must be accounted for in the design of generation IV nuclear reactors that plan to use uranium nitride as a fuel. DA - 2012/10/09 PY - 2012 PB - Nature Publishing Group LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d079ca7c-6010-463f-8e75-5701ce499964 ER - TY - JOUR TI - Evidence for anisotropic polar nanoregions in relaxor Pb(Mg1/3Nb2/3)O3 : a neutron study of the elastic constants and anomalous TA phonon damping in PMN DO - 10.1103/PhysRevB.86.104108 AU - Stock, C. AU - Gehring, P. M. AU - Hiraka, H. AU - Swainson, I. AU - Xu, Guangyong AU - Ye, Z.-G. AU - Luo, H. AU - Li, J.-F. AU - Viehland, D. T2 - Physical Review B VL - 86 IS - 10 SP - 104108-1 EP - 104108-18 DA - 2012/09/18 PY - 2012 PB - American Physical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 834d29f0-fa37-43fe-b120-4a4b9cbdce34 ER - TY - JOUR TI - Characterization of a liquid scintillator based on linear alkyl benzene for neutron detection DO - 10.1016/j.nima.2012.10.127 AU - Bentoumi, G. AU - Dai, X. AU - Fritzsche, H. AU - Jonkmans, G. AU - Li, L. AU - Marleau, G. AU - Sur, B. T2 - Nuclear Instruments and Methods in Physics Research A : Accelerators, Spectrometers, Detectors and Associated Equipment VL - 701 SP - 221 EP - 224 KW - scintillation; boron; linear alkyl benzene; neutron; pulse shape discrimination (PSD) AB - A liquid scintillator (LS) based on linear alkyl benzene (LAB) solvent has been characterized using multiple radiation sources. The results confirm that boron-loaded LAB is suitable for neutron detection in a gamma ray environment. To study indirectly the LAB pulse shape discrimination (PSD) capability between neutrons and gamma rays, a dissolved 212Pb source emitting alpha and beta particles was used to emulate the conditions in a mixed radiation field for detecting neutrons in the presence of a high gamma ray background. The quenching factor depends on the alpha energy and increases from 10 to 25 as the alpha energy decreases from 10 to 1 MeV. 10B loaded LAB-based LS has been tested in a neutron beam of energy which is equal to 14.56 meV. The observed peak at 60 keVee is attributed to the absorption of neutrons. Our results show that a boron-loaded LAB-based scintillator is a sensitive medium for neutron detection in a relatively large background of gamma rays. A neutron detector could be achieved with a figure of merit (FOM) of 1.75. DA - 2012/11/10 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a6b6251b-a952-430b-b0f0-659bd67545e7 ER - TY - JOUR TI - Magnetic order and fluctuations in the presence of quenched disorder in the kagome staircase system (Co1−xMgx)3V2O8 DO - 10.1103/PhysRevB.86.174421 AU - Fritsch, K. AU - Yamani, Z. AU - Chang, S. AU - Qiu, Y. AU - Copley, J. R. D. AU - Ramazanoglu, M. AU - Dabkowska, H. A. AU - Gaulin, B. D. T2 - Physical Review B VL - 86 IS - 17 SP - 174421-1 EP - 174421-10 AB - Co3V2O8 is an orthorhombic magnet in which S=3/2 magnetic moments reside on two crystallographically inequivalent Co2+ sites, which decorate a stacked, buckled version of the two-dimensional kagome lattice, the stacked kagome staircase. The magnetic interactions between the Co2+ moments in this structure lead to a complex magnetic phase diagram at low temperature, wherein it exhibits a series of five transitions below 11 K that ultimately culminate in a ferromagnetic ground state below T∼6.2 K. Here we report magnetization measurements on single- and polycrystalline samples of (Co1−xMgx)3V2O8 for x<0.23, as well as elastic and inelastic neutron scattering measurements on single crystals of magnetically dilute (Co1−xMgx)3V2O8 for x=0.029 and x=0.194, in which nonmagnetic Mg2+ ions substitute for magnetic Co2+. We find that a dilution of 2.9% leads to a suppression of the ferromagnetic transition temperature by ∼15% while a dilution level of 19.4% is sufficient to destroy ferromagnetic long-range order in this material down to a temperature of at least 1.5 K. The magnetic excitation spectrum is characterized by two spin wave branches in the ordered phase for (Co1−xMgx)3V2O8 (x=0.029), similar to that of the pure x=0 material, and by broad diffuse scattering at temperatures below 10 K in (Co1−xMgx)3V2O8 (x=0.194). Such a strong dependence of the transition temperatures on long-range order in the presence of quenched nonmagnetic impurities is consistent with two-dimensional physics driving the transitions. We further provide a simple percolation model that semiquantitatively explains the inability of this system to establish long-range magnetic order at the unusually low dilution levels which we observe in our experiments. DA - 2012/11/21 PY - 2012 PB - Amercian Physical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a131d00f-1181-4a22-9d5e-91173fe38f59 ER - TY - JOUR TI - Neutron scattering studies of spin excitations in superconducting Rb0.82Fe1.68Se2 DO - 10.1103/PhysRevB.86.024502 AU - Wang, Miaoyin AU - Li, Chunhong AU - Abernathy, D. L. AU - Song, Yu AU - Carr, Scott V. AU - Lu, Xingye AU - Li, Shiliang AU - Yamani, Zahra AU - Hu, Jiangping AU - Xiang, Tao AU - Dai, Pengcheng T2 - Physical Review B VL - 86 IS - 2 SP - 024502-1 EP - 024502-2 AB - We use inelastic neutron scattering to show that superconducting (SC) rubidium iron selenide Rb0.82Fe1.68Se2 exhibits antiferromagnetic (AF) spin excitations near the in-plane wave vector Q = (π,0) identical to that for iron arsenide superconductors. Moreover, we find that these excitations change from incommensurate to commensurate with increasing energy and occur √ at the expense of spin waves associated with the coexisting 5 ×√5 block AF phase. Since these spin excitations cannot come from Fermi surface nesting based on angle resolved photoemission experiments, our results indicate the presence of local moments in SC Rb0.82Fe1.68Se2 that may have a similar origin as the hourglass-like spin excitations in copper oxide superconductors. DA - 2012/07/05 PY - 2012 PB - American Physical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6df382e2-a647-4dd0-b634-ac8cbb4e59dd ER - TY - JOUR TI - Electron doping evolution of the anisotropic spin excitations in BaFe2−xNixAs2 DO - 10.1103/PhysRevB.86.024508 AU - Luo, Huiqian AU - Yamani, Zahra AU - Chen, Yanchao AU - Lu, Xingye AU - Wang, Meng AU - Li, Shiliang AU - Maier, Thomas A. AU - Danilkin, Sergey AU - Adroja, D. T. AU - Dai, Pengcheng T2 - Physical Review B VL - 86 IS - 2 SP - 24508-1 EP - 24508-10 DA - 2012/07/10 PY - 2012 PB - American Physical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0629114a-ecc1-4c0d-8b44-13875a58dcf9 ER - TY - JOUR TI - Spin ordering and electronic texture in the bilayer iridate Sr3Ir2O7 DO - 10.1103/PhysRevB.86.100401 AU - Dhital, Chetan AU - Khadka, Sovit AU - Yamani, Z. AU - de la Cruz, Clarina AU - Hogan, T. C. AU - Disseler, S. M. AU - Pokharel, Mani AU - Lukas, K. C. AU - Tian, Wei AU - Opeil, C. P. AU - Wang, Ziqiang AU - Wilson, Stephen D. T2 - Physical Review B VL - 86 IS - 10 SP - 100401-1 EP - 100401-4 AB - Through a neutron scattering, charge transport, and magnetization study, the correlated ground state in the bilayer iridium oxide Sr3Ir2O7 is explored. Our combined results resolve scattering consistent with a high temperature magnetic phase that persists above 600 K, reorients at the previously defined TAF = 280 K, and coexists with an electronic ground state whose phase behavior suggests the formation of a fluctuating charge or orbital phase that freezes below T ∗ ≈ 70 K. Our study provides a window into the emergence of multiple electronic order parameters near the boundary of the metal to insulator phase transition of the 5d Jeff = 1/2Mott phase. DA - 2012/09/07 PY - 2012 PB - American Physical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0a8a64c5-8a4d-426b-8b8d-8c422dfa9cea ER - TY - JOUR TI - Neutron scattering study of URu2−xRexSi2 (x=0.10) : driving order towards quantum criticality DO - 10.1103/PhysRevB.86.235104 AU - Williams, T. J. AU - Yamani, Z. AU - Butch, N. P. AU - Luke, G. M. AU - Maple, M. B. AU - Buyers, W. J. L. T2 - Physical Review B VL - 86 IS - 23 SP - 235104-1 EP - 235104-5 AB - We report inelastic neutron scattering measurements in the hidden order state of URu2−xRexSi2 with x = 0.10. We observe that towards the ferromagnetic quantum critical point induced by the negative chemical pressure of Re doping, the gapped incommensurate fluctuations are robust and comparable in intensity to the parent material. As the Re doping moves the system toward the quantum critical point, the commensurate spin fluctuations related to hidden order weaken, display a shortened lifetime, and slow down. Halfway to the quantum critical point, the hidden order phase survives, albeit weakened, in contrast to its destruction by hydrostatic pressure and by positive chemical pressure from Rh doping. DA - 2012/12/04 PY - 2012 PB - American Physical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a1acc0af-3622-4fa9-9085-e6d3f3148f61 ER - TY - JOUR TI - From once upon a time to happily ever after : tracking emotions in mail and books DO - 10.1016/j.dss.2012.05.030 AU - Mohammad, Saif M. T2 - Decision Support Systems VL - 53 IS - 4 SP - 730 EP - 741 KW - emotion analysis; sentiment analysis; Lexicon; email; fairy tales; Enron Corpus; Google Books Corpus AB - In this paper, we show how sentiment analysis can be used in tandem with effective visualizations to quantify and track emotions in mail and books. We study a number of specific datasets and show, among other things, how collections of texts can be organized for affect-based search and how books portray different entities through co-occurring emotion words. Analysis of the Enron Email Corpus reveals that there are marked differences across genders in how they use emotion words in work-place email. Finally, we show that fairy tales have more extreme emotion densities than novels. DA - 2012/11 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 21e35e1b-8145-48c1-86ba-c15d0213d775 ER - TY - JOUR TI - Staying socially connected with online video communication : a case study AU - Molyneaux, Heather AU - O'Donnell, Susan AU - Milliken, Mary T2 - Canadian Journal of Communication SN - 07005-3657 VL - 37 IS - 3 SP - 421 EP - 440 KW - electronic culture (internet based); video; visual communication AB - Video communication conducted online — online videos, video calls, and videoconferencing — is quickly becoming a fixture in the everyday lives of many Canadians. We conducted a case study of residents of a small Canadian city, exploring their use of video communication to maintain social relationships. Our study indicates high levels of acceptance for communicating using video with others at a geographical distance, especially where there is a cost savings, a close personal relationship between participants, and a need to “show” objects or expressions. Concern about privacy restrains more frequent use. The discussion considers these findings in the context of public sphere theory and the potential for online video communications to be a special kind of place for people to meet and socialize with others. AB - La communication vidéo en ligne – appels vidéo, visioconférences, vidéos affichés en ligne – est rapidement en train de devenir une habitude dans la vie quotidienne de nombreux Canadiens. Nous avons mené une étude de cas sur les résidents d’une petite ville canadienne, explorant leur recours à la communication vidéo pour entretenir leurs relations sociales. Notre étude indique une acceptation enthousiaste de la communication vidéo pour rejoindre les personnes géographiquement éloignées, surtout quand les participants peuvent faire des économies, quand ils ont un rapport étroit avec leurs interlocuteurs et quand ils ont besoin de montrer des objets ou des expressions. Un souci de protéger leur intimité empêche une utilisation encore plus fréquente. La discussion considère ces observations dans le cadre de la théorie de l’espace public et du potentiel des communications vidéo en ligne d’être un lieu spécial permettant au gens de se rencontrer et se fréquenter plus souvent. DA - 2012 PY - 2012 PB - Canadian Journal of Communications Corporation LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ac4fca6f-d3a0-4c10-acbf-f64baad0059f ER - TY - JOUR TI - Data and knowledge visualization with virtual reality spaces, neural networks and rough sets : application to cancer and geophysical prospecting data DO - 10.1016/j.eswa.2012.05.082 AU - Valdés, Julio J. AU - Romero, Enrique AU - Barton, Alan J. T2 - Expert Systems with Applications SN - 0957-4174 VL - 39 IS - 18 SP - 13193 EP - 13201 KW - data and knowledge visualization; visual data mining; virtual reality; data projection; neural networks; rough sets AB - Visual data mining with virtual reality spaces is used for the representation of data and symbolic knowledge. High quality structure-preserving and maximally discriminative visual representations can be obtained using a combination of neural networks (SAMANN and NDA) and rough sets techniques, so that a proper subsequent analysis can be made. The approach is illustrated with two types of data: for gene expression cancer data, an improvement in classification performance with respect to the original spaces was obtained; for geophysical prospecting data for cave detection, a cavity was successfully predicted. DA - 2012/12/15 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 313fd8b5-e49a-4cd5-a515-48fabf6c9e84 ER - TY - JOUR TI - PORT : a precision-order-recall MT evaluation metric for tuning AU - Chen, Boxing AU - Kuhn, Roland AU - Larkin, Samuel T2 - Proceedings of the 50th Annual Meeting of the Association for Computational Linguistics (ACL 2012) T3 - The 50th Annual Meeting of the Association for Computational Linguistics (ACL 2012), 8-14 July 2012, Jeju Island, Korea SN - 9781622761715 VL - 1 SP - 930 EP - 939 AB - Many machine translation (MT) evaluation metrics have been shown to correlate better with human judgment than BLEU. In principle, tuning on these metrics should yield better systems than tuning on BLEU. However, due to issues such as speed, requirements for linguistic resources, and optimization difficulty, they have not been widely adopted for tuning. This paper presents PORT1 , a new MT evaluation metric which combines precision, recall and an ordering metric and which is primarily designed for tuning MT systems. PORT does not require external resources and is quick to compute. It has a better correlation with human judgment than BLEU. We compare PORT-tuned MT systems to BLEU-tuned baselines in five experimental conditions involving four language pairs. PORT tuning achieves consistently better performance than BLEU tuning, according to four automated metrics (including BLEU) and to human evaluation: in comparisons of outputs from 300 source sentences, human judges preferred the PORT-tuned output 45.3% of the time (vs. 32.7% BLEU tuning preferences and 22.0% ties). DA - 2012/07/14 PY - 2012 PB - Curran Associates LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 376a485b-e4c4-4ffe-bc8a-cfae93085e10 ER - TY - JOUR TI - Signal displacement in spiral-in acquisitions : simulations and implications for imaging in SFG regions DO - 10.1016/j.mri.2012.02.014 AU - Brewer, Kimberly D. AU - Rioux, James A. AU - Klassen, Martyn AU - Bowen, Chris V. AU - Beyea, Steven D. T2 - Magnetic Resonance Imaging VL - 30 IS - 6 SP - 753 EP - 763 KW - Functional MRI KW - Susceptibility KW - Artifacts KW - Spiral AB - Susceptibility field gradients (SFGs) cause problems for functional magnetic resonance imaging (fMRI) in regions like the orbital frontal lobes, leading to signal loss and image artifacts (signal displacement and “pile-up”). Pulse sequences with spiral-in k-space trajectories are often used when acquiring fMRI in SFG regions such as inferior/medial temporal cortex because it is believed that they have improved signal recovery and decreased signal displacement properties. Previously postulated theories explain differing reasons why spiral-in appears to perform better than spiral-out; however it is clear that multiple mechanisms are occurring in parallel. This study explores differences in spiral-in and spiral-out images using human and phantom empirical data, as well as simulations consistent with the phantom model. Using image simulations, the displacement of signal was characterized using point spread functions (PSFs) and target maps, the latter of which are conceptually inverse PSFs describing which spatial locations contribute signal to a particular voxel. The magnitude of both PSFs and target maps was found to be identical for spiral-out and spiral-in acquisitions, with signal in target maps being displaced from distant regions in both cases. However, differences in the phase of the signal displacement patterns that consequently lead to changes in the intervoxel phase coherence were found to be a significant mechanism explaining differences between the spiral sequences. The results demonstrate that spiral-in trajectories do preserve more total signal in SFG regions than spiral-out; however, spiral-in does not in fact exhibit decreased signal displacement. Given that this signal can be displaced by significant distances, its recovery may not be preferable for all fMRI applications. DA - 2012/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6ce4bad9-8dd2-4c49-8b42-0f15ca517b1d ER - TY - JOUR TI - Functional MRI of the thoracic spinal cord during vibration sensation DO - 10.1002/jmri.23819 AU - Kornelsen, Jennifer AU - Smith, Stephen D. AU - McIver, Theresa A. AU - Sboto-Frankenstein, Uta AU - Latta, Peter AU - Tomanek, Boguslaw T2 - Journal of Magnetic Resonance Imaging VL - 37 IS - 4 SP - 981 EP - 985 KW - spinal cord KW - cord KW - functional magnetic resonance imaging KW - thoracic KW - vibration KW - sensory AB - Purpose: To demonstrate that it is possible to acquire accurate functional magnetic resonance images from thoracic spinal cord neurons. Materials and Methods: The lower thoracic spinal dermatomes (T7–T11) on the right side of the body were mechanically stimulated by vibration for 15 participants. Neuronal responses to vibration sensation were measured in the thoracic spinal cord using a HASTE sequence on a 3 Tesla MRI system. Results: Signal increases were observed in the corresponding lower thoracic spinal cord segments ipsilateral to the side of stimulation in the dorsal aspect of the spinal cord. Conclusion: This is the first study to provide proof of principle that functional imaging of the entire thoracic spinal cord is possible, by detecting neuronal activity in the thoracic spinal cord during sensory stimulation using spinal fMRI. DA - 2012/09/25 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 85cda38c-9432-4b03-b6b0-f1a8091b7825 ER - TY - GEN TI - ALEX: a mobile speech and language learning assistant AU - Munteanu, Cosmin AU - Molyneaux, Heather AU - McDonald, Daniel AU - Leung, Rock T3 - Seventh Workshop on Speech (and Sound) in Mobile and Pervasive Environments in conjunction with MobileHCI'12 the 14th International Conference on Human-Computer Interaction with Mobile Devices and Services, 21 September 2012, San Francisco, California, USA KW - mobile computing; interface design; mobile learning; assistive technology; speech and language support AB - For a very large number of adults in developed countries, tasks such as reading, understanding, and using everyday items are a challenge. Many community-based organizations offer resources and support for adults with limited literacy skills; unfortunately, current programs have difficulty reaching and retaining those that would benefit most. To address these challenges, we have developed a mobile application to support literacy programs and to assist low-literacy adults in today's information-centric society. ALEX© (Adult Literacy support application for EXperiential learning) is a mobile speech and language assistant that is designed to be used both in the classroom and in daily life in order to help low-literacy adults become increasingly literate and independent. DA - 2012/09/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ea892d8a-0304-4fe1-b580-e2dc29af19a7 ER - TY - JOUR TI - Fast on-line learning for multilingual categorization DO - 10.1145/2348283.2348474 AU - Kovesi, Michelle AU - Goutte, Cyril AU - Amini, Massih-Reza T2 - SIGIR '12: Proceedings of the 35th international ACM SIGIR conference on Research and development in information retrieval T3 - SIGIR 2012 The 35th International ACM SIGIR conference on research and development in Information Retrieval, August 12-16, 2012, Portland, Oregon, USA SP - 1071 EP - 1072 KW - multilingual text categorisation; on-line learning AB - Multiview learning has been shown to be a natural and efficient framework for supervised or semi-supervised learning of multilingual document categorizers. The state-of-the-art co-regularization approach relies on alternate minimizations of a combination of language-specific categorization errors and a disagreement between the outputs of the monolingual text categorizers. This is typically solved by repeatedly training categorizers on each language with the appropriate regularizer. We extend and improve this approach by introducing an on-line learning scheme, where language-specific updates are interleaved in order to iteratively optimize the global cost in one pass. Our experimental results show that this produces similar performance as the batch approach, at a fraction of the computational cost. DA - 2012/08 PY - 2012 PB - ACM LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 36bd0934-6224-461c-a0b6-4200036db00f ER - TY - CHAP TI - Active 3D imaging systems DO - 10.1007/978-1-4471-4063-4_3 AU - Drouin, Marc-Antoine AU - Beraldin, Jean-Angelo T2 - 3D Imaging, Analysis and Applications SN - 978-1-4471-4062-7 SP - 95 EP - 138 AB - Active 3D imaging systems use artificial illumination in order to capture and record digital representations of objects. The use of artificial illumination allows the acquisition of dense and accurate range images of textureless objects that are difficult to acquire using passive vision systems. An active 3D imaging system can be based on different measurement principles that include time-of-flight, triangulation and interferometry. While time-of-flight and interferometry systems are briefly discussed, an in-depth description of triangulation-based systems is provided. The characterization of triangulation-based systems is discussed using both an error propagation framework and experimental protocols. DA - 2012/12 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b3a7ff46-605a-483d-9880-9c6de889694d ER - TY - JOUR TI - 3D anthropometric data processing DO - 10.1504/IJHFMS.2012.051093 AU - Shu, Chang AU - Wuhrer, Stefanie AU - Xi, Pengcheng T2 - International Journal of Human Factors Modelling and Simulation VL - 3 IS - 2 SP - 133 EP - 146 KW - statistical shape analysis; 3D anthropometry; geometry processing; human shape models; digital human models; digital human modelling; DHM; anthropometric data processing; product design; data completion; data compression; visualisation AB - 3D anthropometric data obtained from 3D imaging technology provide unprecedented information about the human shape. At the same time, 3D data present tremendous challenges. New software tools and analytical methods have to be designed to realise the full potential of the 3D data. One prominent character of the 3D data is that they are a collection of coordinates in 3-space and do not have a natural order. This poses problems for performing statistical analysis. In order to make sense about this type of data, 3D points have to be registered such that meaningful correspondences across all the models can be established. Other issues include data completion, compression, and visualisation. In this paper, we describe a framework and the techniques involved in processing the 3D anthropometric data for the purpose of making them usable for designing products that fit the human shapes. DA - 2012/12 PY - 2012 PB - Inderscience Enterprises LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c7218656-9391-4d66-93ee-295b12ddc02a ER - TY - JOUR TI - Targeting the latest hallmark of cancer : another attempt at 'magic bullet' drugs targeting cancers' metabolic phenotype DO - 10.2217/fon.12.121 AU - Cuperlovic-Culf, M. AU - Culf, A. S. AU - Touaibia, M. AU - Lefort, N. T2 - Future Oncology VL - 8 IS - 10 SP - 1315 EP - 1330 AB - The metabolism of tumors is remarkably different from the metabolism of corresponding normal cells and tissues. Metabolic alterations are initiated by oncogenes and are required for malignant transformation, allowing cancer cells to resist some cell death signals while producing energy and fulfilling their biosynthetic needs with limiting resources. The distinct metabolic phenotype of cancers provides an interesting avenue for treatment, potentially with minimal side effects. As many cancers show similar metabolic characteristics, drugs targeting the cancer metabolic phenotype are, perhaps optimistically, expected to be 'magic bullet' treatments. Over the last few years there have been a number of potential drugs developed to specifically target cancer metabolism. Several of these drugs are currently in clinical and preclinical trials. This review outlines examples of drugs developed for different targets of significance to cancer metabolism, with a focus on small molecule leads, chemical biology and clinical results for these drugs. DA - 2012/10 PY - 2012 PB - Future Medicine LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c637aaf5-b210-4043-b1ab-ddeef7ed8212 ER - TY - JOUR TI - GD & T-based characterization of short-range non-contact 3D imaging systems DO - 10.1007/s11263-012-0570-3 AU - MacKinnon, David AU - Carrier, Benjamin AU - Beraldin, Jean-Angelo AU - Cournoyer, Luc T2 - International Journal of Computer Vision SN - 0920-5691 VL - 102 IS - 1-3 SP - 56 EP - 72 KW - characterization; GD & T; 3D imaging systems; quality analysis; spatial metrology; 3D metrology AB - We present a series of test metrics, artifacts, and procedures for characterizing and verifying the operating limits of a short-range non-contact three-dimensional imaging system. These metrics have been designed to correspond to dimensioning and tolerancing metrics that are widely used in industry (e.g. automotive, aerospace, etc.). We introduce operating limit metrics that correspond with the geometric dimensioning and tolerancing (GD&T) metrics of Form (Flatness and Circularity), Orientation (Angularity), Location (Sphere, Corner, and Hole Position Errors), and Size (Diameter, Sphere-spacing, Plane-spacing and Angle Errors). An example is presented to illustrate how these metrics, artifacts, and associated test procedures can be used in practice. DA - 2012/10/13 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a0959304-e8c6-4b55-8c52-425d0f566323 ER - TY - CHAP TI - Fast 3D spine reconstruction of postoperative patients using a multilevel statistical model DO - 10.1007/978-3-642-33418-4_55 AU - Lecron, Fabian AU - Boisvert, Jonathan AU - Mahmoudi, Saïd AU - Labelle, Hubert AU - Benjelloun, Mohammed T2 - Medical Image Computing and Computer-Assisted Intervention – MICCAI 2012 : 15th International Conference, Nice, France, October 1-5, 2012, Proceedings, Part II T2 - Lecture Notes In Computer Science; 7511 T3 - 15th International Conference on Medical Image Computing and Computer-Assisted Intervention (MICCAI 2012), October 1-5, 2012, Nice, France SN - 0302-9743 SN - 978-3-642-33417-7 SN - 978-3-642-33418-4 VL - 7511 SP - 446 EP - 453 KW - 3D reconstruction; spine; statistical shape model; multilevel modeling AB - Severe cases of spinal deformities such as scoliosis are usually treated by a surgery where instrumentation (hooks, screws and rods) is installed to the spine to correct deformities. Even if the purpose is to obtain a normal spine curve, the result is often straighter than normal. In this paper, we propose a fast statistical reconstruction algorithm based on a general model which can deal with such instrumented spines. To this end, we present the concept of multilevel statistical model where the data are decomposed into a within-group and a between-group component. The reconstruction procedure is formulated as a second-order cone program which can be solved very fast (few tenths of a second). Reconstruction errors were evaluated on real patient data and results showed that multilevel modeling allows better 3D reconstruction than classical models. DA - 2012/12 PY - 2012 PB - Springer Berlin Heidelberg LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 94a1e287-477c-46f4-b248-71162647f8c9 ER - TY - JOUR TI - Crossing the barrier : a scalable simulator for course of fire training AU - Fournier, H. AU - Lapointe, J.-F. AU - Kondratova, I. AU - Emond, B. AU - Munteanu, C. T2 - Proceedings of Interservice/Industry Training, Simulation, and Education Conference (I/ITSEC) 2012 T3 - Interservice/Industry Training, Simulation, and Education Conference (I/ITSEC) 2012, 3-6 December 2012, Orlando, Florida, USA IS - 12187 AB - The growing training and operational needs of law enforcement and public safety personnel can no longer be met efficiently and effectively through existing infrastructure and resources. While the demands of day-to-day operations are constantly changing, the training of law enforcement personnel and certification process has largely stayed the same. While several technological solutions exist for enhancing training, widespread adoption of current approaches and solutions, such as virtual training, is hindered by significant cost barriers and by lack of scalability and reach. This creates challenges for smaller geographically disconnected units, which characterizes most rural police departments in North America. This paper presents MINT-PD, a technological solution for multimodal virtual Course of Fire (COF) training, along with field observations and validation of the technology. One specific application of MINT-PD is to help to increase the rate of success among the trainees who failed a first COF certification round. Success in this context represents significant cost savings by reducing active-duty officers' down-time due to the remedial training and reducing the need for the use of the live firing range. MINT-PD is based on the Multimodal Interactive Trainer (MINT) simulation platform developed by NRC, specifically adapted to address user needs in training and certification for a typical municipal police department. MINT-PD technology allows users to modify training scenarios, incorporate different types of laser guns and a flashlight, add avatars, and expand the training to include Use of Force scenarios. The conditions and parameters implemented in the virtual COF simulator have been derived from field observations and validated by COF trainers within a medium-size police department. This process of technology development and validation will be described in the paper. DA - 2012/12/06 PY - 2012 PB - National Training and Simulation Association LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1f13bb8b-7661-4e52-acd2-719c85da1a1f ER - TY - JOUR TI - Tracking complete deformable objects with finite elements DO - 10.1109/3DIMPVT.2012.16 AU - Wuhrer, Stefanie AU - Lang, Jochen AU - Shu, Chang T2 - 3DIMPVT 2012 Conference Proceedings T3 - 2nd Joint International Conference on 3DIM/3DPVT (3D Imaging, Modeling, Processing, Visualization and Transmission), 13-15 October 2012, Zürich, Switzerland SN - 978-1-4673-4470-8 SP - 1 EP - 8 AB - We present an approach to robustly track the geometry of an object that deforms over time from a set of input point clouds captured from a single viewpoint. The deformations we consider are caused by applying forces to known locations on the object’s surface. Our method combines the use of prior information on the geometry of the object modeled by a smooth template and the use of a linear finite element method to predict the deformation. This allows the accurate reconstruction of both the observed and the unobserved sides of the object. We present tracking results for noisy low-quality point clouds acquired by a stereo camera and a Kinect sensor, and simulations with point clouds corrupted by different error terms. We show that our method is also applicable to large non-linear deformations. DA - 2012/10 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2cefd55a-3e51-4ef1-a437-b84e6f6a15f8 ER - TY - JOUR TI - Towards an ontology for autonomous robots DO - 10.1109/IROS.2012.6386119 AU - Paull, Liam AU - Severac, Gaetan AU - Raffo, Guilherme V. AU - Angel, Julian Mauricio AU - Boley, Harold AU - Durst, Phillip J. AU - Gray, Wendell AU - Habib, Maki AU - Nguyen, Bao AU - Ragavan, S. Veera AU - Saeedi G., Sajad AU - Sanz, Ricardo AU - Seto, Mae AU - Stefanovski, Aleksandar AU - Trentini, Michael AU - Li, Howard T2 - 2012 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS) T3 - 2012 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 7-12 October 2012, Vilamoura, Algarve, Portugal SN - 2153-0858 SN - 978-1-4673-1737-5 SP - 1359 EP - 1364 AB - The IEEE RAS Ontologies for Robotics and Automation Working Group is dedicated to developing a methodology for knowledge representation and reasoning in robotics and automation. As part of this working group, the Autonomous Robots sub-group is tasked with developing ontology modules for autonomous robots. This paper describes the work in progress on the development of ontologies for autonomous systems. For autonomous systems, the focus is on the cooperation, coordination, and communication of multiple unmanned aerial vehicles (UAVs), unmanned ground vehicles (UGVs), and autonomous underwater vehicles (AUVs). The ontologies serve as a framework for working out concepts of employment with multiple vehicles for a variety of operational scenarios with emphasis on collaborative and cooperative missions. DA - 2012/12 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 17f58b37-ab0d-4a72-be1e-05ba1edbc02d ER - TY - CHAP TI - Model fusion-based batch learning with application to oil spills detection DO - 10.1007/978-3-642-31087-4_5 AU - Yang, Chunsheng AU - Yang, Yubin AU - Liu, Jie T2 - Advanced Research in Applied Artificial Intelligence T2 - Lecture Notes In Computer Science; 7345 T3 - 25th International Conference on Industrial Engineering and Other Applications of Applied Intelligent Systems (IEA/AIE 2012), June 9-12, 2012, Dalian, China SN - 0302-9743 SN - 978-3-642-31086-7 SN - 978-3-642-31087-4 SP - 40 EP - 47 KW - Batch Data KW - Batch Learning KW - Transfer Learning KW - Content-based Learning KW - Model Fusion KW - Oil Spill Detection AB - Data split into batches is very common in real-world applications. In speech recognition and handwriting identification, the batches are different people. In areas like oil spill detection and train wheel failure prediction, the batches are the particular circumstances when the readings were recorded. The recent research has proved that it is important to respect the batch structure when learning models for batched data. We believe that such a batch structure is also an opportunity that can be exploited in the learning process. In this paper, we investigated the novel method for dealing with the batched data. We applied the developed batch learning techniques to detect oil spills using radar images collected from satellite stations. This paper reports some progress on the proposed batch learning method and the preliminary results obtained from oil spills detection. DA - 2012/08/01 PY - 2012 PB - Springer Berlin Heidelberg LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 88a95ade-a09f-4fd7-9ed3-0d651f2bfb75 ER - TY - JOUR TI - A phonon scattering assisted injection and extraction based terahertz quantum cascade laser DO - 10.1063/1.3702571 AU - Dupont, E. AU - Fathololoumi, S. AU - Wasilewski, Z. R. AU - Aers, G. AU - Laframboise, S. R. AU - Lindskog, M. AU - Razavipour, S. G. AU - Wacker, A. AU - Ban, D. AU - Liu, H. C. T2 - Journal of Applied Physics VL - 111 IS - 7 SP - 073111-1 EP - 073111-10 AB - A lasing scheme for terahertz quantum cascade lasers, based on consecutive phonon-photon-phonon emissions per module, is proposed and experimentally demonstrated. The charge transport of the proposed structure is modeled using a rate equation formalism. An optimization code based on a genetic algorithm was developed to find a four-well design in the GaAs/Al0.25Ga0.75As material system that maximizes the product of population inversion and oscillator strength at 150 K. The fabricated devices using Au double-metal waveguides show lasing at 3.2 THz up to 138 K. The electrical characteristics display no sign of differential resistance drop at lasing threshold, which, in conjunction with the low optical power of the device, suggest—thanks to the rate equation model—a slow depopulation rate of the lower lasing state, a hypothesis confirmed by non-equilibrium Green’s function calculations. DA - 2012/04/12 PY - 2012 PB - Amercian Institute of Physics LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 28e6da46-0709-43f1-8630-b668d82e1c53 ER - TY - JOUR TI - Learning with aggregation and correlation in the presence of large fluctuations AU - Paquet, Eric AU - Viktor, Herna L. AU - Guo, Hongyu T2 - Proceedings of New Frontiers in Mining Complex Patterns (NFMCP 2012) T3 - NFMCP 2012 : International Workshop on New Frontiers in Mining Complex Patterns in conjunction with the ECML/PKDD-2012 (European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases), 24-28 September 2012, Bristol, UK SP - 12 EP - 23 KW - aggregation in relational learning; correlation-based analysis and covariance; lévy distribution; stable distribution AB - Consider a scenario where one aims to learn models from dynamic and evolving data being characterized by very large fluctuations that are neither attributable to noise nor outliers. This may be the case, for instance, when predicting the potential future damages of earthquakes or oil spills, or when conducting financial data analysis. If follows that, in such a situation, the standard central limit theorem does not apply, since the associated Gaussian distribution exponentially suppresses large fluctuations. In this paper, we present an analysis of data aggregation and correlation in such scenarios. To this end, we introduce the Lévy, or stable, distribution which is a generalization of the Gaussian distribution. Our theoretical conclusions are illustrated with various simulations, as well as against a benchmarking financial database. We show which specific strategies should be adopted for aggregation, depending on the stability exponent of the Lévy distribution. Our results firstly show scenarios where it may be impossible to determine the mean and the standard deviation of an aggregate. Secondly, we discuss the case where an aggregate may have to be characterized with its largest fluctuations. Thirdly, we illustrate that the correlation in between two attributes may be underestimated if a Gaussian distribution is erroneously assumed. DA - 2012/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b9860f27-54db-41a7-a16f-662aab2c6528 ER - TY - GEN TI - Conditional significance pruning : discarding more of huge phrase tables AU - Johnson, J. Howard T3 - The Tenth Biennial Conference of the Association for Machine Translation in the Americas (AMTA), 28 October - 1 November 2012, San Diego, California, USA AB - The technique of pruning phrase tables that are used for statistical machine translation (SMT) can achieve substantial reductions in bulk and improve translation quality, especially for very large corpora such at the Giga- FrEn. This can be further improved by conditioning each significance test on other phrase pair co-occurrence counts resulting in an additional reduction in size and increase in BLEU score. A series of experiments using Moses and the WMT11 corpora for French to English have been performed to quantify the improvement. By adhering strictly to the recommendations for the WMT11 baseline system, a strong reproducible research baseline was employed. DA - 2012/11/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bb26b75e-ff34-47e4-82db-2f71940cf9bf ER - TY - JOUR TI - Thermal performance of wall assemblies with low emissivity DO - 10.1177/1744259112450419 AU - Saber, Hamed H. T2 - Journal of Building Physics SN - 1744-2591 SN - 1744-2583 VL - 36 IS - 3 SP - 308 EP - 329 KW - Reflective insulation; furred-airspace assembly; low emissivity material; thermal modelling; thermal resistance test method; R-value; heat flow meter; ASTM C-518; ASTM C-1363; airflow; heat transfer by convection; conduction and radiation AB - In wall systems, airspaces can increase thermal resistance if a reflective material such as foil with low emissivity is installed in a Furred-Airspace Assembly (FAA). In this paper, the present model, hygIRC-C, was used to investigate the steady-state thermal resistance of wall assemblies that incorporate foil adhered to expanded polystyrene (EPS) foam in a furred-assembly. To investigate the effect of the furring orientation, the furring was installed horizontally and vertically and compared to walls with no furring. For wall with vertical furring, the 3D version of the present model was used to capture the 3D effect of the thermal bridges. Because the foil emissivity can be affected by dust accumulation and/or water vapor condensation on the foil surface, consideration was given to investigate the effect of both varying foil emissivity and outdoor temperature on the thermal performance of the various wall specimens. Results showed that the thermal resistance (R-value) of the reference wall (no furring) is greater than the wall specimens with furring. Also, results showed that the contribution of the FAA to the R-value of wall specimen with vertical furring is higher than that for wall specimen with horizontal furring. DA - 2012/12/23 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 932a7ce2-88ef-4d2a-9e53-365e7be5cd41 ER - TY - JOUR TI - Numerical modeling and experimental investigations of thermal performance of reflective insulations DO - 10.1177/1744259112444021 AU - Saber, Hamed H. AU - Maref, Wahid AU - Sherrer, Gordon AU - Swinton, Michael C. T2 - Journal of Building Physics SN - 1744-2591 SN - 1744-2583 VL - 36 IS - 2 SP - 163 EP - 177 KW - Reflective insulation; furred-airspace assembly; low emissivity material; thermal modelling; thermal resistance test method; R-value; heat flow meter; ASTM C-518; ASTM C-1363; airflow; heat transfer by convection; conduction and radiation AB - Reflective insulations are being used in attics, flat roof, and wall systems. Numerical modeling and experimental investigations were conducted to assess the thermal performance of assemblies with reflective insulations. In this article, the present model was used to verify the use of the ASTM C-518 test method for measuring the effective thermal resistances (R-values) of sample stacks comprising reflective insulations. Two tests were conducted on sample stacks using heat flow meter apparatus. The sample stack consists of two expanded polystyrene layers and a reflective insulation installed in between. The model predictions agreed with the measured heat fluxes within ±1%. The article also discusses the combined effect of heat transfer by convection and radiation in the airspace facing the reflective insulation, showing that the derived R-value from the test data resulted in underestimation of the effective R-value of the sample stack DA - 2012/10/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 74cb81ef-cf82-43ba-ae04-bb4ba9e2dde1 ER - TY - JOUR TI - A new testing capability for seismic resistance assessment of structures damaged due to a fire AU - Mostafaei, Hossein T2 - The 15th World Conference on Earthquake Engineering (WCEE) Proceedings T3 - The 15th WCEE: World Conference on Earthquake Engineering, Sept 24-28, 2012, Lisbon, Portugal SP - 1 EP - 8 KW - Fire damage; seismic resistance; reinforced concrete; column; hybrid test; fire resistance; performance-based evaluation AB - This paper provides results of a hybrid structural test that simulates residual lateral load resistance of a structure after fire damage. The simulation was carried out at the National Research Council of Canada (NRC) using the NRC’s furnace facilities. The hybrid test included two substructures; a structural element/assembly specimen, here a column specimen, and a model component, here the remaining of the structure. Using this method, first, fire damage was imposed to a structure, a 6-storey reinforced concrete building, and six days later, after the entire structure had cooled down to the ambient temperature, the building was subjected to a lateral load, which was determined based on a design seismic load. The test results showed a reduction of both residual lateral stiffness and residual lateral load capacity of the structure after the fire damage. This paper will present the hybrid test, its application and the results for the 6-storey building. DA - 2012/09/28 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 26777537-692c-4681-ad66-314b50cb6e59 ER - TY - JOUR TI - Effect of furring orientation on thermal response of wall systems with low emissivity material and furred-airspace AU - Saber, Hamed H. AU - Maref, Wahid T2 - BEST 3 2012: The Building Enclosure Science and Technoloogy Conference Proceedings T3 - Building Enclosure Council Science and Technology 3 (BEST 3) Conference: High Performance Building - Combining Field Experience and Innovation, April 2-4, 2012, Atlanta, GA. SP - 1 EP - 15 KW - Reflective insulation; Furred-Airspace Assembly (FAA); low emissivity material; thermal modelling; thermal resistance; R-value; airflow; heat transfer by convection; conduction and radiation AB - In wall systems, airspaces can contribute in obtaining a higher thermal resistance, if a reflective material such as foil with low emissivity is installed on one side or the other of a Furred-Airspace Assembly. In this paper, the present model, hygIRC-C, was used to investigate the steady-state thermal performance of wall specimens that incorporate foil bonded to expanded polystyrene (EPS) foam in a furred-assembly having airspace next to the foil. In order to investigate the effect of the furring orientation on the wall thermal performance, the furring was installed horizontally and/or vertically. Also, a reference wall similar to these walls but with no furring was considered. For the reference wall and wall with horizontal furring, the 2D version of the present model is suitable to model these wall assemblies. However, for wall with vertical furring, the 3D version of the present model was used in order to capture the 3D effect of the thermal bridges due to the vertical furring on the energy transport and momentum transport in the wall system. Consideration was given to investigate the effect the foil emissivity and outdoor temperature on the contribution of the FAA on the thermal performance of the wall systems. Results showed that the thermal resistance (R-value) of the reference wall (no furring) is greater than the wall systems with furring. Also, results showed that the contribution of the FAA to the R-value of wall system with vertical furring is higher than that for wall system with horizontal furring. DA - 2012/04/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 770dfd34-2e8d-435a-950f-286457ff9210 ER - TY - JOUR TI - The effect of window-wall interface details on window condensation potential AU - Maref, W. AU - Van Den Bossche, N. AU - Armstrong, M. AU - Lacasse, M. A. AU - Elmahdy, H. AU - Glazer, R. T2 - BEST 3 2012: Building Enclosure Science and Technology Conference Proceedings T3 - Building Enclosure Council Science and Technology 3 (BEST 3) Conference: High Performance Building - Combining Field Experience and Innovation, April 2-4, 2012, Atlanta, GA. SP - 1 EP - 6 KW - Laboratory test; condensation; window-wall interface; box-window AB - Considering all building components, windows typically have the lowest surface temperature, and will consequently be the primary location for interior surface condensation. Those surface temperatures can easily be calculated using thermal finite-element-models (FEM), and there is an ISO standard with guidelines for condensation risk assessment. However, both the FEM-simulations as the ISO standard generally omit the effect of air flows in and around window frames. When cold air is drawn into the construction, the airflow might cool down specific components of the window-wall interface depending on the location of the airflow path. Consequently, the current evaluation method for condensation risk assessment based on FEM-simulations might underestimate the actual risk. There is a need to determine if interface details become more susceptible for surface condensation due to pressure differences over the component. This paper reports on a laboratory evaluation of condensation risk assessment in a hotbox, with varying pressure differences and the introduction of deficiencies. It was concluded that the effect of the type of insulation in the window-wall interface was very low for isobaric boundary conditions, whereas it has a significant effect when pressure differences are applied. A full paper on this topic has been accepted for publication by the Journal of Building Physics. DA - 2012/06/28 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 60e85cc5-3cf7-47e0-830c-d3129759d643 ER - TY - JOUR TI - Reducing the size of databases for multirelational classification : a subgraph-based approach DO - 10.1007/s10844-012-0229-0 AU - Guo, Hongyu AU - Viktor, Herna L. AU - Paquet, Eric T2 - Journal of Intelligent Information Systems SN - 0925-9902 VL - November 2012 KW - multi-relational classification; relational data mining AB - Multirelational classification aims to discover patterns across multiple interlinked tables (relations) in a relational database. In many large organizations, such a database often spans numerous departments and/or subdivisions, which are involved in different aspects of the enterprise such as customer profiling, fraud detection, inventory management, financial management, and so on. When considering classification, different phases of the knowledge discovery process are affected by economic utility. For instance, in the data preprocessing process, one must consider the cost associated with acquiring, cleaning, and transforming large volumes of data. When training and testing the data mining models, one has to consider the impact of the data size on the running time of the learning algorithm. In order to address these utility-based issues, the paper presents an approach to create a pruned database for multirelational classification, while minimizing predictive performance loss on the final model. Our method identifies a set of strongly uncorrelated subgraphs from the original database schema, to use for training, and discards all others. The experiments performed show that our strategy is able to, without sacrificing predictive accuracy, significantly reduce the size of the databases, in terms of the number of relations, tuples, and attributes.The approach prunes the sizes of databases by as much as 94 %. Such reduction also results in decreasing computational cost of the learning process. The method improves the multirelational learning algorithms’ execution time by as much as 80 %. In particular, our results demonstrate that one may build an accurate model with only a small subset of the provided database. DA - 2012/11/29 PY - 2012 PB - Springer US LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 490f5160-072f-428f-b1f7-1ba0011ead5e ER - TY - JOUR TI - Fundamentals of Neurosurgery : virtual reality tasks for training and evaluation of technical skills DO - 10.1016/j.wneu.2012.08.022 AU - Choudhury, Nusrat AU - Gélinas-Phaneuf, Nicholas AU - Delorme, Sébastien AU - Del Maestro, Rolando T2 - World Neurosurgery KW - neurosurgery KW - clinical skills KW - computer simulation KW - training KW - virtual systems AB - Background: Technical skills training in neurosurgery is mostly done in the operating room. New educational paradigms are encouraging the development of novel training methods for surgical skills. Simulation could answer some of these needs. This paper presents the development of a conceptual training framework for use on a virtual reality (VR) neurosurgical simulator. Methods: Appropriate tasks were identified by reviewing neurosurgical oncology curricula requirements and performing cognitive task analyses of basic techniques and representative surgeries. The tasks were then elaborated into training modules by including learning objectives, instructions, levels of difficulty and performance metrics. Surveys and interviews were iteratively conducted with subject matter experts (SMEs) to delimitate, review, discuss and approve each of the development stages. Results: Five tasks were selected as representative of basic and advanced neurosurgical skill. These tasks were: 1) ventriculostomy, 2) endoscopic nasal navigation, 3) tumour debulking, 4) hemostasis and 5) microdissection. The complete training modules were structured into easy, intermediate and advanced settings. Performance metrics were also integrated to provide feedback on outcome, efficiency and errors. The SMEs deemed the proposed modules as pertinent and useful for neurosurgical skills training. Conclusion: The conceptual framework presented here, the Fundamentals of Neurosurgery (FNS), represents a first attempt to develop standardized training modules for technical skills acquisition in neurosurgical oncology. The National Research Council Canada is currently developing NeuroTouch, a VR simulator for cranial microneurosurgery. The simulator presently includes the five FNS modules at varying stages of completion. A first pilot study has shown that neurosurgical residents obtained higher performance scores on the simulator than medical students. Further work will validate its components and use in a training curriculum. DA - 2012/11/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 482c4848-9237-41e1-bb5d-d4de3928c82a ER - TY - JOUR TI - Comparison of NRC goniometric and integrating sphere methods for realizing an absolute diffuse reflectance scale DO - 10.1117/12.930794 AU - Baribeau, Réjean AU - Zwinkels, Joanne T2 - Reflection, Scattering, and Diffraction from Surfaces III T2 - Proceedings of SPIE; 8495 T3 - Rlection, Scattering, and Diffraction from Surfaces III, 13-16 August 2012, San Diego, California, USA SP - 8495-10 SP - 84950A-1 EP - 84950A-10 KW - diffuse reflectance; BRDF; goniometric method; sphere method; uncertainty AB - At the National Research Council of Canada (NRC), the scale of diffuse spectral reflectance in the UV and visible range is realized using an integrating sphere method known as the Modified Sharp-Little method and has been wellcharacterized and validated. More recently, a gonioreflectometer has been designed to capture the bidirectional reflectance of reflecting objects. This system incorporates a diode-array spectroradiometer and is prone to non-linearity errors. In this paper the magnitude of this non-linearity error is evaluated using several diffusely reflecting materials by comparing the angular-integrated reflection indicatrix measured with the gonioreflectometer with results obtained using a transfer spectrophotometer that is traceable to the sphere-based NRC Absolute Reflectometer. DA - 2012/10/16 PY - 2012 PB - SPIE--the International Society for Optical Engineering LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ed9dde53-9ea6-47ed-8875-cfcc993a8640 ER - TY - JOUR TI - Apple peel flavonoid- and triterpene-enriched extracts differentially affect cholesterol homeostasis in hamsters DO - 10.1016/j.jff.2012.07.004 AU - Thilakarathna, Surangi H. AU - Wang, Yanwen AU - Rupasinghe, H. P. Vasantha AU - Ghanam, Khadija T2 - Journal of Functional Foods VL - 4 IS - 4 SP - 963 EP - 791 KW - Apple peel extracts KW - Flavonoids KW - Triterpenes KW - Hamster KW - Cholesterol KW - Oxidative stress AB - Flavonoids and triterpenes are two major groups of bioactive compounds in apple peels. This study determined whether flavonoid-rich (FAE) and triterpene-rich (TAE) apple peel extracts affect cholesterol metabolism in diet-induced hypercholesterolemic male Golden Syrian hamsters. Two groups of hamsters were supplemented with 50 mg bioactives/kg/d of FAE or TAE and the third group was the atherogenic control (AC). After 28 days, FAE reduced (p < 0.05) serum total cholesterol (TC) and non-high density lipoprotein cholesterol (non-HDL) compared to AC. In contrast, TAE increased (p < 0.05) serum TC. Extracts had no effect on serum triacylglycerol and HDL. Both FAE and TAE increased (p < 0.05) cholesterol absorption without any effect on cholesterol biosynthesis. Liver TC, free cholesterol, triacylglycerol, serum and liver oxidative stress biomarkers were not altered by any extract. FAE and TAE differentially affected cholesterol metabolism where FAE effectively lowered serum cholesterol, with the underlying mechanism awaiting further investigation. DA - 2012/08/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ac59166f-fa7a-40f5-85cb-ad5fb5a5bf90 ER - TY - JOUR TI - Variable temperature 17O NMR studies allow quantitative evaluation of molecular dynamics and hydrogem bond energies in organic solids DO - 10.1021/ja306227p AU - Kong, Xianqi AU - O'Dell, Luke A. AU - Terskikh, Victor AU - Ye, Eric AU - Wang, Ruiyao AU - Wu, Gang T2 - Journal of the American Chemical Society VL - 134 IS - 35 SP - 14609 EP - 14617 AB - We report a comprehensive variable-temperature solid-state 17O NMR study of three 17O-labeled crystalline sulfonic acids: 2-aminoethane-1-sulfonic acid (taurine, T), 3- aminopropane-1-sulfonic acid (homotaurine, HT), and 4-aminobutane- 1-sulfonic acid (ABSA). In the solid state, all three compounds exist as zwitterionic structures, NH3+−R−SO3−, in which the SO3− group is involved in various degrees of O···H−N hydrogen bonding. High-quality 17O NMR spectra have been obtained for all three compounds under both static and magic angle spinning (MAS) conditions at 21.1 T, allowing the complete set of 17O NMR tensor parameters to be measured. Assignment of the observed 17O NMR parameters to the correct oxygen sites in the crystal lattice was achieved with the aid of DFT calculations. By modeling the temperature dependence of 17O NMR powder line shapes, we have not only confirmed that the SO3− groups in these compounds undergo a 3-fold rotational jump mechanism but also extracted the corresponding jump rates (102−105 s−1) and the associated activation energies (Ea) for this process (Ea = 48 ± 7, 42 ± 3, and 45 ± 1 kJ mol−1 for T, HT, and ABSA, respectively). This is the first time that SO3− rotational dynamics have been directly probed by solid-state 17O NMR. Using the experimental activation energies for SO3− rotation, we were able to evaluate quantitatively the total hydrogen bond energy that each SO3− group is involved in within the crystal lattice. The activation energies also correlate with calculated rotational energy barriers. This work provides a clear illustration of the utility of solid-state 17O NMR in quantifying dynamic processes occurring in organic solids. Similar studies applied to selectively 17O-labeled biomolecules would appear to be very feasible. DA - 2012/08/10 PY - 2012 PB - American Chemical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : aeae244f-b5e6-4cb0-a2c2-6b8d918c18dc ER - TY - JOUR TI - Dark state suppression and optimization of laser cooling and fluorescence in a trapped alkaline-earth-metal single ion DO - 10.1103/PhysRevA.86.033403 AU - Lindvall, T. AU - Merimaa, M. AU - Tittonen, I. AU - Madej, A. A. T2 - Physical Review A VL - 86 IS - 3 SP - 033403-1 EP - 033403-12 AB - We study the formation and destabilization of dark states in a single trapped ⁸⁸Sr⁺ ion caused by the cooling and repumping laser fields required for Doppler cooling and fluorescence detection of the ion. By numerically solving the time-dependent density matrix equations for the eight-level system consisting of the sublevels of the 5s 2 S1/2, 5p 2 P1/2, and 4d 2 D3/2 states, we analyze the different types of dark states and how to prevent them in order to maximize the scattering rate, which is crucial for both the cooling and the detection of the ion. The influence of the laser linewidths and ion motion on the scattering rate and the dark resonances is studied. The calculations are then compared with experimental results obtained with an endcap ion trap system located at the National Research Council of Canada and found to be in good agreement. The results are applicable also to other alkaline-earth-metal ions and isotopes without hyperfine structure. DA - 2012/09/04 PY - 2012 PB - American Physical Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2f4ac418-d145-4622-a23d-2e54d59b62dd ER - TY - JOUR TI - Thermodynamic temperature measurements of the melting temperatures of Co-C, Pt-C, and Re-C fixed points at NRC DO - 10.1088/0026-1394/50/1/20 AU - Todd, A. D. W. AU - Woods, D. J. T2 - Metrologia VL - 50 IS - 1 SP - MET/432504/PAP SP - 20 EP - 26 KW - instrumentation and measurement general; condensed matter: structural, mechanical & thermal AB - This paper outlines measurements made at the National Research Council Canada (NRC) of the thermodynamic melting temperatures of Co–C, Pt–C and Re–C fixed points that have been part of the high-temperature fixed-point research plan of Working Group 5 of the Consultative Committee for Thermometry (CCT-WG5) to assign melting temperatures to those fixed points. This document will outline the equipment used, describe the scheme used to calibrate a pyrometer with traceability to a cryogenic electrical substitution radiometer, and detail the method of measuring the fixed points. It will then report the uncertainties in the measurements and the results. A brief description of the improvements that we plan to implement to the scheme to reduce the uncertainties for future measurements will be given. The thermodynamic temperatures determined for the three fixed points are: 1597.776 K with an expanded uncertainty of 0.36 K, 2011.390 K with an expanded uncertainty of 0.55 K, and 2748.056 K with an expanded uncertainty of 0.95 K, for the Co–C, Pt–C and Re–C fixed points, respectively (all expanded uncertainties assume a 95% confidence interval and a Gaussian distribution). DA - 2012/12/19 PY - 2012 PB - IOP Publishing LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 08e57116-3d17-4873-8b75-86d7682a1031 ER - TY - JOUR TI - Effect of pH on neutral lipid and biomass accumulation in microalgal strains native to the Canadian prairies and the Athabasca oil sands DO - 10.1007/s10811-012-9930-1 AU - Skrupski, B. AU - Wison, K. E. AU - Goff, K. L. AU - Zou, J. T2 - Journal of Applied Phycology KW - Biodiesel KW - Lipid KW - Oil Sands KW - pH Stress KW - Nile Red KW - Biomass KW - TAG AB - Algal biodiesel has been a subject of growing importance in the realm of renewable energy due to carbon capture properties and its potential for photosynthetic efficiency with high lipid output. This study identified five isolates of freshwater green algae, belonging to the Chlorellaceae, and measured the lipid classes and fatty acid profiles of these species to determine suitability for biodiesel production. To induce the greater accumulation of lipids, especially in the form of triacylglycerols (TAGs) desired for biodiesel, we examined the lipid accumulation in cells stressed by nitrogen limitation, sulfur deficiency, or pH stress. Increases in biomass were monitored in order to determine if adjusting pH incrementally over the course of the experiment had any effect on growth and lipid accumulation of several isolates. TAG accumulation was visually screened by Nile Red fluorescence and further assessed by gas chromatography. Lipid amounts were comparably equal or better for pH stress treatments than for standard nutrient-deprivation treatments. Incrementally adjusted pH over the course of growth triggered lipid accumulation comparable to constant pH stress treatments, yet biomass accumulation was equivalent to unstressed growth. One isolate obtained from the Athabasca oil-sands region of Alberta, OS4-2, is a good candidate for biodiesel production, having accumulated over 45 % of its dry weight as lipid, with over 80 % of the lipid as triacylglycerols, and contains an abundance of 18:1 fatty acids. This class of fatty acids improves the cold flow and oxidative stability of biodiesel and is ideal for biofuel used in a Canadian climate. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a12a73e4-c4f5-4236-8543-b3963ddb5c61 ER - TY - JOUR TI - L-Tryptophan ethyl ester dilates small mesenteric arteries by inhibition of voltage-operated calcium channels in smooth muscle DO - 10.1111/j.1476-5381.2011.01693.x AU - Jadhav, Ashok AU - Liang, Wenbin AU - Balsevich, John AU - Bastin, Guillaume AU - Kroetsch, Jeff AU - Heximer, Scott AU - Backx, Peter H. AU - Gopalakrishnon, Venkat T2 - British Journal of Pharmacology VL - 166 IS - 1 SP - 232 EP - 242 KW - aorta KW - Ba²⁺ current KW - blood pressure KW - L-tryptophan KW - L-tryptophan ethyl ester KW - mesenteric artery KW - phenylephrine KW - potassium chloride KW - voltage-operated Ca²⁺ channel AB - BACKGROUND AND PURPOSE: L-tryptophan (L-W) is a precursor of the vasoconstrictor, 5-HT. However, acute administration of L-W ethyl ester (L-Wee) lowered blood pressure. The mechanism of action is unknown. This study compares the vascular effects of L-W and L-Wee in intact animals, isolated aortic rings, small mesenteric arteries (MA) and explores possible mechanisms by studies in vascular smooth muscle cells (VSMC) of MA. EXPERIMENTAL APPROACH: Effects of L-W or L-Wee (5–50 mg kg⁻¹, i.v.) on mean arterial pressure (MAP) and heart rate (HR) were determined in male Sprague-Dawley rats. The effects of L-W and L-Wee on basal tone and of phenylephrine- or KCl-induced contractions of aortic and MA rings were assessed. Effects of L-Wee and L-W on voltage-operated calcium channels (VOCC) of VSMC of MA were also examined in patch-clamp studies. KEY RESULTS: Administration of L-Wee, but not L-W, evoked a rapid and transient dose-dependent decrease in MAP and HR. While both agents failed to affect basal tone, L-Wee decreased, concentration-dependently, (Imax > 98%) tension responses to phenylephrine and KCl in an endothelium-independent manner in aorta (IC₅₀ 2 mM) and MA (IC₅₀ 17 μM). L-Wee evoked concentration-dependent inhibition of VOCC currents (IC₅₀ 12 μM; Imax 90%) in VSMC of MA. CONCLUSIONS AND IMPLICATIONS: Esterified L-W (L-Wee), but not L-W, preferentially relaxed resistance vessels rather than conduit vessels. These effects were associated with blockade of VOCC by L-Wee. Our findings suggest that the falls in MAP and HR induced by L-Wee were due to blockade of VOCC by L-Wee. DA - 2012/04/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fd990543-d078-43c9-b4f9-4815e9db850a ER - TY - JOUR TI - Brassica carinata CIL1 mediates extracellular ROS production during Auxin- and ABA-regulated lateral root development DO - 10.1007/s12374-011-0328-4 AU - Gibson, Shawn W. AU - Conway, Alix J. AU - Zheng, Zhifu AU - Uchacz, Tina M. AU - Taylor, Janet L. AU - Todd, Christopher D. T2 - Journal of Plant Biology VL - 55 IS - 5 SP - 361 EP - 372 KW - Abscisic acid KW - Auxin KW - Brassica carinata KW - Glucosylphosphatidylinositol-anchored protein KW - Lateral roots KW - Reactive oxygen species AB - ct In the plant cytoplasm signals from multiple sources interact to control development. Lateral root proliferation is controlled by the antagonistic action of the hormones auxin and abscisic acid (ABA). Auxin stimulates the separation of pericycle initials and cell expansion. ABA is required for lateral root initiation and elongation and acts as an antagonist through auxin-dependent pathways. These hormones also mediate reactive oxygen species (ROS) accumulation in growing roots and promote cell expansion. We describe the isolation and characterization of a copperand auxin-induced gene, COPPER INDUCED in LEAVES (CIL1), from Brassica carinata. Transgenic B. carinata seedlings expressing antisense CIL1 were used to determine the biological function of this gene. Lines with reduced CIL1 expression showed a decrease in lateral root development, as well as reduced sensitivity to auxin and ABA. Steady-state analysis of redox components showed a decrease in NADPH oxidase, superoxide dismutase, and catalase activity, accompanied by an increase in hydrogen peroxide concentration. GFP-tagged CIL1 accumulated at the plasma membrane and in the apoplast indicating CIL1 is likely extracellular. From these data we propose that CIL1 is an extracellular protein involved in ROS cycling mediating auxin and ABA signals. DA - 2012/10/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 53cbc53c-222a-45a0-9ec5-68d9f7f1f337 ER - TY - JOUR TI - Arabidopsis Clade I TGA transcription factors regulate plant defenses in an NPR1-independent fashion DO - 10.1094/MPMI-09-11-0256 AU - Shearer, Heather L. AU - Cheng, Yu Ti AU - Wang, Lipu AU - Liu, Jinman AU - Boyle, Patrick AU - Després, Charles AU - Zhang, Yuelin AU - Li, Xin AU - Fobert, Pierre R. T2 - Molecular Plant-Microbe Interactions VL - 25 IS - 11 SP - 1459 EP - 1468 AB - Transcriptional reprogramming during induction of salicylic acid (SA)-mediated defenses is regulated primarily by NPR1 (NONEXPRESSOR OF PATHOGENESIS-RELATED GENES 1), likely through interactions with TGA bZIP transcription factors. To ascertain the contributions of clade I TGA factors (TGA1 and TGA4) to defense responses, a tga1-1 tga4-1 double mutant was constructed and challenged with Pseudomonas syringae and Hyaloperonospora arabidopsidis. Although the mutant displayed enhanced susceptibility to virulent P. syringae, it was not compromised in systemic acquired resistance against this pathogen or resistance against avirulent H. arabidopsidis. Microarray analysis of nonelicited and SA-treated plants indicated that clade I TGA factors regulate fewer genes than NPR1. Approximately half of TGA-dependent genes were regulated by NPR1 but, in all cases, the direction of change was opposite in the two mutants. In support of the microarray data, the NPR1-independent disease resistance observed in the autoimmune resistance (R) gene mutant snc1 is partly compromised by tga1-1 tga4-1 mutations, and a triple mutant of clade I TGA factors with npr1-1 is more susceptible than either parent. These results suggest that clade I TGA factors are required for resistance against virulent pathogens and avirulent pathogens mediated by at least some R gene specificities, acting substantially through NPR1-independent pathways. DA - 2012/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6c68d7bc-d217-45d0-afb7-9af4e313ed1f ER - TY - JOUR TI - Topological study of mechanistic diversity in conjugated fatty acid biosynthesis DO - 10.1002/anie.201202080 AU - Bhar, Palash AU - Reed, Darwin W. AU - Covello, Patrick S. AU - Buist, Peter H. T2 - Angewandte Chemie International Edition VL - 51 IS - 27 SP - 6686 EP - 6690 KW - C−H activation KW - desaturases KW - enzyme mechanisms KW - kinetic isotope effects KW - conformation analysis AB - Variations on an oxidative theme: The precision with which FAD2-type desaturases carry out C−H activation reactions on flexible lipidic substrates is astonishing. The conformational space available within the active site of these enzymes has been explored using deuterium-labeled substrates, and evidence for a novel quasi-eclipsed conformer has been uncovered. The scheme shows some prototypical substrate conformations. DA - 2012/05/23 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fa710324-f63e-4cc1-b7b6-f0391d33fdde ER - TY - GEN TI - Laser-induced incandescence (LII) for the measurement of atmospheric black carbon DO - 10.4224/21186089 AU - Smallwood, Gregory T3 - Council on Optical Radiation Measurements 2012 Annual Technical Conference, 29 May - 1 June 2012, Ottawa, Ontario, Canada DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e7253c28-12dc-4ea3-a714-0dc3cc455827 ER - TY - JOUR TI - Functional characterization of amyrin synthase involved in ursolic acid biosynthesis in Catharanthus roseus leaf epidermis DO - 10.1016/j.phytochem.2012.05.002 AU - Yu, Fang AU - Thamm, Antje M. K. AU - Reed, Darwin AU - Villa-Ruano, Nemesio AU - Quesada, Alfonso Lara AU - Lozoya, Edmundo Gloria AU - Covello, Patrick AU - De Luca, Vincenzo T2 - Phytochemistry KW - Catharanthus amyrin synthase KW - Leaf epidermis expression KW - Ursolic acid KW - Secretion AB - Catharanthus roseus accumulates high levels of the pentacyclic triterpene, ursolic acid, as a component of its wax exudate on the leaf surface. Bioinformatic analyses of transcripts derived from the leaf epidermis provide evidence for the specialized role of this tissue in the biosynthesis of ursolic acid. Cloning and functional expression in yeast of a triterpene synthase derived from this tissue showed it to be predominantly an α-amyrin synthase (CrAS), since the α-amyrin to β-amyrin reaction products accumulated in a 5:1 ratio. Expression analysis of CrAS showed that triterpene biosynthesis occurs predominantly in the youngest leaf tissues and in the earliest stages of seedling development. Further studies using laser capture microdissection to harvest RNA from epidermis, mesophyll, idioblasts, laticifers and vasculature of leaves showed the leaf epidermis to be the preferred sites of CrAS expression and provide conclusive evidence for the involvement of this tissue in the biosynthesis of ursolic acid in C. roseus. DA - 2012/05/29 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f6d7cd02-ef0f-45dc-bdf5-7b7588641fb1 ER - TY - JOUR TI - Improved localization accuracy in magnetic source imaging using a 3-D laser scanner DO - 10.1109/TBME.2012.2220356 AU - Bardouille, Timothy AU - Krishnamurthy, Santosh V. AU - Ghosh Hajra, Sujoy AU - D'Arcy, Ryan C. N. T2 - IEEE Transactions on Biomedical Engineering VL - 59 IS - 12 SP - 3491 EP - 3497 KW - Coregistration KW - laser scanner KW - localization accuracy KW - magnetic resonance imaging (MRI) KW - magnetoencephalography (MEG) AB - Brain source localization accuracy in magnetoencephalography (MEG) requires accuracy in both digitizing anatomical landmarks and coregistering to anatomical magnetic resonance images (MRI). We compared the source localization accuracy and MEG-MRI coregistration accuracy of two head digitization systems—a laser scanner and the current standard electromagnetic digitization system (Polhemus)—using a calibrated phantom and human data. When compared using the calibrated phantom, surface and source localization accuracy for data acquired with the laser scanner improved over the Polhemus by 141% and 132%, respectively. Laser scan digitization reduced MEG source localization error by 1.38 mm on average. In human participants, a laser scan of the face generated a 1000-fold more points per unit time than the Polhemus head digitization. An automated surfacematching algorithm improved the accuracy of MEG-MRI coregistration over the equivalent manual procedure. Simulations showed that the laser scan coverage could be reduced to an area around the eyes only while maintaining coregistration accuracy, suggesting that acquisition time can be substantially reduced. Our results show that the laser scanner can both reduce setup time and improve localization accuracy, in comparison to the Polhemus digitization system. DA - 2012/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a3fe32d3-6ef8-40b3-940e-5e79a2e7be6d ER - TY - JOUR TI - Nonlinear optical microscopy in decoding arterial diseases DO - 10.1007/s12551-012-0077-8 AU - Ko, Alex C.-T. AU - Ridsdale, Andrew AU - Mostaço-Guidolin, Leila B. AU - Major, Arkady AU - Stolow, Albert AU - Sowa, Michael G. T2 - Biophysical Reviews VL - 4 IS - 4 SP - 323 EP - 334 KW - Atherosclerosis KW - Nonlinear optical microscopy KW - Second-harmonic generation KW - Two-photon excited fluorescence KW - Coherent anti-Stokes Raman KW - Artery AB - Pathological understanding of arterial diseases is mainly attributable to histological observations based on conventional tissue staining protocols. The emerging development of nonlinear optical microscopy (NLOM), particularly in second-harmonic generation, two-photon excited fluorescence and coherent Raman scattering, provides a new venue to visualize pathological changes in the extracellular matrix caused by atherosclerosis progression. These techniques in general require minimal tissue preparation and offer rapid three-dimensional imaging. The capability of label-free microscopic imaging enables disease impact to be studied directly on the bulk artery tissue, thus minimally perturbing the sample. In this review, we look at recent progress in applications related to arterial disease imaging using various forms of NLOM. DA - 2012/05/17 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 09f20a48-1e98-4b86-9450-44c3b4bb2841 ER - TY - JOUR TI - A Lagrangian level set-like method for modelling and simulation in bioengineering DO - 10.1080/10255842.2012.738197 AU - Mir, Hicham AU - Thibault, Francis T2 - Computer Methods in Biomechanics and Biomedical Engineering SN - 1025-5842 KW - Lagrangian level set method KW - FEM KW - solid mechanics AB - The level set method has been used for 20 years in a wide range of physical applications to track moving interfaces instead of an explicit description of the geometry. This paper studies in detail the shape of the level set function, delimiting a sub-domain in solid mechanics, with an innovative update method based on the computation of a displacement field obtained with the values of the level set function. A criterion based on the values of the level set function is proposed in order to assign the material properties. With the help of this criterion, an optimal approach is proposed, which predicts an accurate evolution of the sub-domain boundary. To validate this method, it was first applied in two dimensions to a through-thickness hole plate case, and then to the cases of brain tumour expansion and grasping to demonstrate the applicability of the method. DA - 2012/12/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 590a578b-58ff-4f95-8b0c-8f7a14f5fadf ER - TY - JOUR TI - Optimal signal processing of nonlinearity in swept-source and spectral-domain optical coherence tomography DO - 10.1364/AO.51.001701 AU - Vergnole, Sébastien AU - Lévesque, Daniel AU - Bizheva, Kostadinka AU - Lamouche, Guy T2 - Applied Optics VL - 51 IS - 11 SP - 1701 EP - 1708 AB - We demonstrate the efficiency of the convolution using an optimized Kaiser–Bessel window to resample nonlinear data in wavenumber for Fourier-domain optical coherence tomography (OCT). We extend our previous experimental demonstration that was performed with a specific swept-source nonlinearity. The method is now applied to swept-source OCT data obtained for various simulated swept-source nonlinearities as well as spectral-domain OCT data obtained from both simulations and experiments. Results show that the new optimized method is the most efficient for handling all the different types of nonlinearities in the wavenumber domain that one can encounter in normal practice. The efficiency of the method is evaluated through comparison with common methods using resampling through interpolation prior to performing a fast-Fourier transform and with the accurate but time-consuming discrete Fourier transform for unequally spaced data, which involves Vandermonde matrices. DA - 2012/04/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e62d5caf-fb81-4307-a5cf-dd1ad6dd6918 ER - TY - JOUR TI - Non-destructive detection of lack of penetration defects in friction stir welds DO - 10.1179/1362171812Y.0000000007 AU - Mandache, C. AU - Levesque, D. AU - Dubourg, L. AU - Gougeon, P. T2 - Science and Technology of Welding & Joining VL - 17 IS - 4 SP - 295 EP - 303 KW - Non-destructive evaluation KW - Friction stir welding KW - Lack of penetration KW - Eddy current KW - Ultrasonic waves KW - Inspection AB - This study focuses on the comparative investigation of different non-destructive inspection (NDI) techniques for detecting the lack of penetration discontinuities in butt joint friction stir (FS) welds. A variably sized lack of penetration has been introduced purposely by progressively changing the tool pin’s length. While inspecting the weld from the discontinuity side provides results of higher sensitivity, service inspection of the FS welded components requires evaluation of the welding tool’s side, opposite the defect containing one. Non-destructive techniques amenable for inspection from either the tool side or the far side of the weld are analysed, and results from inspection are presented for comparison. Subsequently, bending tests and metallographic examinations were employed to confirm the size of the lack of penetration defects and correlate these results with the NDI capabilities. DA - 2012/05/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ab7b86e4-e147-40b7-9d5c-aafb42b248da ER - TY - JOUR TI - Haptic collision handling for simulation of transnasal surgery DO - 10.1002/cav.1489 AU - Neubauer, André AU - Brooks, Rupert AU - Brouwer, Iman AU - Debergue, Patricia AU - Laroche, Denis T2 - Computer Animation and Virtual Worlds VL - 24 IS - 2 SP - 127 EP - 141 KW - surgical simulation KW - transnasal endoscopy KW - collision handling KW - haptics KW - virtual coupling AB - Simulation of endoscopic navigation in the narrow nasal cavity poses important challenges to the computation of adequate and near-realistic collision response and haptic feedback because extensive multidirectional contact and massive tissue deformations are inevitable. We present a virtual coupling algorithm that provides stable collision response as well as intuitive and smooth haptic interaction in all phases of the simulation. In each iteration, continuous collision detection between the point shell representing the surface of the virtual patient anatomy and the endoscope, represented by a cylinder, is performed. This allows for rolling back the instrument movement to the point in time the first collision occurred. Subsequently, a relaxation process locally optimizes the position and orientation of the instrument. A novel method of applying contact forces to colliding tissues and thus triggering appropriate deformations improves the fluency of navigation. This paper describes the algorithm and presents experimental results. DA - 2012/10/23 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e466f389-50b0-4629-9e54-2c80164317d1 ER - TY - JOUR TI - The influence of pore size on osteoblast phenotype expression in cultures grown on porous titanium DO - 10.1016/j.ijom.2012.02.020 AU - Teixeira, L. N. AU - Crippa, G. E. AU - Lefebvre, L.-P. AU - De Oliveira, P. T. AU - Rosa, A. L. AU - Beloti, M. M. T2 - International Journal of Oral and Maxillofacial Surgery VL - 41 IS - 9 SP - 1097 EP - 1101 KW - cell culture KW - osteoblast KW - dental implant KW - pore size KW - porous titanium AB - This study investigated the effect of pore size on osteoblastic phenotype development in cultures grown on porous titanium (Ti). Porous Ti discs with three different pore sizes, 312 μm (Ti 312), 130 μm (Ti 130) and 62 μm (Ti 62) were fabricated using a powder metallurgy process. Osteoblastic cells obtained from human alveolar bone were cultured on porous Ti samples for periods of up to 14 days. Cell proliferation was affected by pore size at day 3 (p = 0.0010), day 7 (p = 0.0005) and day 10 (p = 0.0090) in the following way: Ti 62 < Ti 130 < Ti 312. Gene expression of bone markers evaluated at 14 days was affected, RUNX2 (p = 0.0153), ALP (p = 0.0153), BSP (p = 0.0156), COL (p = 0.0156), and OPN (p = 0.0156) by pore size as follows: Ti 312 < Ti 130 < Ti 62. Based on these results, the authors suggest that porous Ti surfaces with pore sizes near 62 μm, compared with those of 312 μm and 130 μm, yield the highest expression of osteoblast phenotype as indicated by the lower cell proliferation rate and higher gene expression of bone markers. DA - 2012/04/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 68aa0d4c-29fa-477a-8c2c-36d93942732d ER - TY - JOUR TI - Melt-processing and properties of coaxial fibers incorporating carbon nanotubes AU - Laforgue, Alexis AU - Champagne, Michel F. AU - Dumas, Jean AU - Robitaille, Lucie T2 - Journal of Engineered Fibers and Fabrics VL - 7 IS - 3 SP - 118 EP - 124 AB - Polypropylene-multiwalled carbon nanotube (PPCNT) composites were spun into fibers using meltspinning methods. The CNT content was varied by diluting the commercial masterbatch with a low viscosity PP homopolymer grade. The conductivity, as well as the mechanical properties, of the fibers were systematically tested in order to find the optimal formulation. Post-stretching was used to improve the mechanical properties of the fibers as well as to decrease the fiber diameters. Fibers having a conductivity of 0.4 S/cm, a Young’s modulus of 5.4 GPa and a tensile strength of 250 MPa were obtained after a three-fold stretching. Trilayer coaxial fibers similar to data transfer coaxial cables (two conductive layers separated by an insulating layer) were then produced in a one-step melt-spinning method using a specially designed die, followed by solid state post-stretching. DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b7a2992c-3208-4700-b752-d759d007ae4e ER - TY - JOUR TI - Numerical simulation of fluid–solid interaction using an immersed boundary finite element method DO - 10.1016/j.compfluid.2012.02.008 AU - Ilinca, F. AU - Hétu, J.-F. T2 - Computers & Fluids VL - 59 SP - 31 EP - 43 KW - Immersed boundary method KW - Fluid-solid interaction KW - Finite elements KW - Non-body-conformal mesh KW - Body conformal enrichment AB - This paper presents applications of a recently proposed immersed boundary method to the solution of fluid–solid interaction. Solid objects immersed into the fluid are considered rigid and their movement is determined from the interaction forces with the fluid. The use of body-conformal meshes to solve such problems may involve extensive mesh adaptation work that has to be repeated each time a change in the shape of the domain or in the position of immersed solids is needed. Mesh generation and solution interpolation between successive grids may be costly and introduce errors if the geometry changes signifi- cantly during the course of the computation. These drawbacks are avoided when the solution algorithm can tackle grids that do not fit the shape of immersed objects. We present here an extension of our recently developed immersed boundary (IB) finite element method to the computation of interaction forces between the fluid and immersed solid bodies. A fixed mesh is used covering both the fluid and solid regions, and the boundary of immersed objects is defined using a time dependent level-set function. Boundary conditions on the immersed solid surfaces are imposed accurately by using a Body Conformal Enrichment (BCE) method. In this approach, the finite element discretization of interface elements is enriched by including additional degrees of freedom which are latter eliminated at element level. The forces acting on the solid surfaces are computed from the enriched finite element solution and the solid movement is determined from the rigid solid momentum equations. Solutions are shown for various fluid–solid interaction problems and the accuracy of the present approach is measured with respect to solutions on body-conformal meshes. DA - 2012/02/24 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 01dd97ee-cfe9-4d5b-ad1c-138b509062c2 ER - TY - JOUR TI - The effect of deposition conditions on adhesion strength of Ti and Ti6Al4V cold spray splats DO - 10.1007/s11666-011-9720-3 AU - Goldbaum, Dina AU - Shockley, J. Michael AU - Chromik, Richard R. AU - Rezaeian, Ahmad AU - Yue, Stephen AU - Legoux, Jean-Gabriel AU - Irissou, Eric T2 - Journal of Thermal Spray Technology VL - 21 IS - 2 SP - 288 EP - 303 KW - adhesion KW - cold spray KW - splats KW - Ti KW - Ti6A14V AB - Cold spray is a complex process where many parameters have to be considered in order to achieve optimized material deposition and properties. In the cold spray process, deposition velocity influences the degree of material deformation and material adhesion. While most materials can be easily deposited at relatively low deposition velocity (<700 m/s), this is not the case for high yield strength materials like Ti and its alloys. In the present study, we evaluate the effects of deposition velocity, powder size, particle position in the gas jet, gas temperature, and substrate temperature on the adhesion strength of cold spayed Ti and Ti6Al4V splats. A micromechanical test technique was used to shear individual splats of Ti or Ti6Al4V and measure their adhesion strength. The splats were deposited onto Ti or Ti6Al4V substrates over a range of deposition conditions with either nitrogen or helium as the propelling gas. The splat adhesion testing coupled with microstructural characterization was used to define the strength, the type and the continuity of the bonded interface between splat and substrate material. The results demonstrated that optimization of spray conditions makes it possible to obtain splats with continuous bonding along the splat/substrate interface and measured adhesion strengths approaching the shear strength of bulk material. The parameters shown to improve the splat adhesion included the increase of the splat deposition velocity well above the critical deposition velocity of the tested material, increase in the temperature of both powder and the substrate material, decrease in the powder size, and optimization of the flow dynamics for the cold spray gun nozzle. Through comparisons to the literature, the adhesion strength of Ti splats measured with the splat adhesion technique correlated well with the cohesion strength of Ti coatings deposited under similar conditions and measured with tubular coating tensile (TCT) test. DA - 2012/03/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9dc04801-1be6-42e2-b72a-1ae6846efdeb ER - TY - JOUR TI - Thermal cycling of suspension plasma sprayed Alumina-YSZ coatings containing amorphous phases DO - 10.1111/j.1551-2916.2012.05292.x AU - Tarasi, Fariba AU - Medraj, Mamoun AU - Dolatabadi, Ali AU - Lima, Rogerio S. AU - Moreau, Christian T2 - Journal of the American Ceramic Society VL - 95 IS - 8 SP - 2614 EP - 2621 KW - thermal cyclic test KW - amorphous phase KW - composite ceramic KW - alumina-zirconia KW - thermal barrier coating AB - Thermal cyclic test at 1080°C for various numbers of cycles was performed on suspension plasma-sprayed coatings of alumina-yttria-stabilized zirconia composites and yttria-stabilized zirconia (YSZ). The structural variations of composite coatings were studied to verify the possibility of production of nano-composite coatings with nano-dispersed oxides. The results showed that this composite exhibited a lower thermally grown oxide growth than that of the YSZ. New multi-constituent composites formed of alternative regions of nano-precipitates of alumina in zirconia matrix and nano-precipitates of zirconia in alumina matrix were developed via phase transformation through thermal cyclic process of amorphous-containing structure. DA - 2012/06/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ff825d2a-9ff7-4155-acec-c3fb0af98948 ER - TY - JOUR TI - Non-contact biomedical photoacoustic and ultrasound imaging DO - 10.1117/1.JBO.17.6.061217 AU - Rousseau, Guy AU - Gauthier, Bruno AU - Blouin, Alain AU - Monchalin, Jean-Pierre T2 - Journal of Biomedical Optics VL - 17 IS - 6 SP - 061217-1 EP - 061217-7 KW - photoacoustic tomography KW - tomography KW - photoacoustic imaging KW - ultrasound imaging KW - optical detection of ultrasound KW - optical coherence tomography KW - brain surgery KW - blood oxygenation AB - The detection of ultrasound in photoacoustic tomography (PAT) usually relies on ultrasonic transducers in contact with the biological tissue through a coupling medium. This is a major drawback for important potential applications such as surgery. Here we report the use of a remote optical method, derived from industrial laserultrasonics, to detect ultrasound in tissues. This approach enables non-contact PAT (NCPAT) without exceeding laser exposure safety limits. The sensitivity of the method is based on the use of suitably shaped detection laser pulses and a confocal Fabry-Perot interferometer in differential configuration. Reliable image reconstruction is obtained by measuring remotely the surface profile of the tissue with an optical coherence tomography system. The proposed method also allows non-contact ultrasound imaging (US) by applying a second reconstruction algorithm to the data acquired for NCPAT. Endogenous and exogenous inclusions exhibiting optical and acoustic contrasts were detected ex vivo in chicken breast and calf brain specimens. Inclusions down to 0.3 mm in size were detected at depths exceeding 1 cm. The method could expand the scope of photoacoustic and US to in-vivo biomedical applications where contact is impractical. DA - 2012/05/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fd7c770b-b17e-49ca-abd5-570d859d38b8 ER - TY - JOUR TI - Performance of conventional and new lubricants used for single compaction of steel PM parts AU - Thomas, Yannig AU - St. Laurent, Sylvain AU - Paris, Vincent AU - Tinto, Rio T2 - Advances in Powder Metallurgy & Particulate Materials—2012 : Proceedings of the 2012 International Conference on Powder Metallurgy & Particulate Materials, 10-13 June, Nashville, Tennessee T3 - 2012 International Conference on Powder Metallurgy & Particulate Materials (PowderMet 2012), 10-13 June 2012, Nashville, Tennessee, USA AB - The role of lubricant during compaction is crucial and is even more important those days with the increased number of PM parts with higher densities and/or challenging ejection conditions. It is for that reason that significant level of efforts were devoted during the last 20 years to the development of environmental friendly PM lubricants that improve both the compaction processing of steel pre-mixes such as the ejection, density, robustness, productivity, surface finish, etc., as well as the performances of the PM parts after sintering. The development of new lubricants for single compaction requires an excellent understanding of the lubrication mechanisms and the behaviour of these new compounds. In this presentation, the effect of different compacting processing parameters such as the pressure, temperature, compaction speed and part aspect ratio on the lubrication behaviour of iron-based powder mixes containing various types of lubricants are reviewed. A particular attention will also be given to the effect of the type and concentration of lubricants on the delubrication behaviour and mechanical properties obtained after sintering. DA - 2012/06/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9aaf9c82-9e76-4664-ac6a-d912efd666b6 ER - TY - JOUR TI - DLFT experiments with cyclic butylene terephtalate AU - Bravo, Victor L. AU - Mihalich, James AU - McLeod, Martin R. AU - Bureau, Martin N. T2 - SPE Automotive and Composites Divisions - 12th Annual Automotive Composites Conference and Exhibition 2012, ACCE 2012: Unleashing the Power of Design T3 - 12th Annual Automotive Composites Conference & Exhibition (ACCE 2012), 11-13 September 2012, Troy, Michigan, USA SN - 9781622768875 SP - 110 EP - 122 KW - Automotive applications KW - Cyclic butylene terephthalates KW - High molecular weight KW - Homogeneous mixtures KW - Material temperature KW - Poly(butylene terephthalate) KW - Polymerization process KW - Processing equipment KW - Automobile exhibitions KW - Butenes KW - Composite materials KW - Glass fibers KW - Mechanical properties KW - Molecular weight KW - Oligomers KW - Polymerization KW - Reinforcement KW - Residence time distribution KW - Viscosity KW - Molds AB - Cyclic oligomers have low molecular weights and therefore exhibit very low viscosities (in the order of 20 mPa.s) in contrast to the resulting high viscosities related to high molecular weightsobtained after polymerization. This characteristic is very appealing for the production of polymer composites since by taking advantage of the low viscosity, fibres can be thoroughly wetted by the cyclic oligomer before starting the reactive process of polymerization. As a result, a homogeneous mixture with a uniform volumetric distribution of reinforcing fibres in the polymer matrix is expected with the use of appropriate processing equipment. Cyclic butylene terephthalate (CBT®) has been successfully polymerized into poly(butylene terephthalate) (PBT) using a variety of tin or titanate-based initiators. An exploratory project has been initiated by NRC at the Magna-NRC Composites Centre of Excellence (MNCCE) with the participation of Cyclics Corporation (Cyclics) as the supplier of CBT for trials using the D-LFT process. The goal is to assess a number of aspects involved in the simultaneous reactive extrusion/compounding process using CBT fibreglass reinforcement in a D-LFT process in order to determine the adequate processing conditions to produce parts. This paper presents a description of the experiments conducted up to date and the results obtained thereby. Parts were produced using a test specimen mould with a shot-pot device and a storage tub for automotive applications. Samples were characterized for tensile, flexural and impact tests. Density measurements were taken at different points of the tub to examine the uniformity of the composite material obtained. Plaques moulded with the test specimen mould showed good mechanical properties which exceed typical values for PP with 40% glass composites. The experiments proved the feasibility of the use of the open ring polymerization process in a D-LFT system. A set of operating conditions including temperature profile, screw speed and feed rate was established to achieve the adequate residence time and material temperature history for the effective processing of CBT in the D-LFT system.Mechanical properties measured from the moulded part (tub) showed significantly lower values than those for the test specimen mould. These were related to incomplete packing of the material in the cavity of the mould, the high residence time required and non-optimal shot size.High variability within the parts and between parts produced is thought to be a consequence of the processing difficulties for the tub mould. DA - 2012/09/13 PY - 2012 PB - Curran LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 956ab768-30fc-4a91-b7b2-1747dea631a5 ER - TY - JOUR TI - Effect of process variables on the performance of glass fibre reinforced composites made by high pressure resin transfer moulding AU - Khoun, Loleï AU - Maillard, Damien AU - Bureau, Martin N. T2 - Proceedings of the 12th Annual Automotive Composites Conference & Exhibition (ACCE 2012) T3 - 12th Annual Automotive Composites Conference & Exhibition (ACCE 2012), 11-13 September 2012, Troy, Michigan, USA SN - 978-1-62276-887-5 SP - 380 AB - The CAFE regulations will require average fuel consumption of cars and light duty trucks to be reduced from 27 mpg to 54.5 mpg by 2025. In order to reach this requirement, automakers have to improve both the vehicle powertrain efficiency and the vehicle weight. Polymer composite materials are a preferred alternative to achieve the needed weight reduction by combining a higher strength to weight ratio than steel and aluminum, superior fatigue and corrosion resistance than metal and very good crashworthiness characteristics. However, high throughput and cost effective composite manufacturing processes are essential for high performance fibre reinforced polymer composites to penetrate the automotive market to their full potential. High Pressure Resin Transfer Moulding (HP-RTM) process is a new process based on the Resin Transfer Moulding (RTM) technology that enables the processing of very reactive resins in very short cycle times (< 5-10 min i.e. >25,000 parts per year) with various types of reinforcement (glass, carbon, natural fibre). With HP-RTM’s unique self-cleaning impingement mixhead, resins that react in less than 1 minute (fast-curing epoxy or polyurethane systems) can still be processed. This process, combining the high mechanical performance of RTM parts with short cure cycle, thus presents a great interest for automotive applications. In this study, the effect of the process parameters, such as the injection flow rate, the vacuum assistance sequence and mould gap control, on the mechanical performance and quality of HP-RTM composite plates was determined and HP-RTM process mapping was established from the obtained mechanical results. DA - 2012/09/13 PY - 2012 PB - Curran LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f1b008ab-a89d-43a5-8d01-ee328d85eefe ER - TY - JOUR TI - Atmospheric plasma sprayed forsterite (Mg2ASiO4) coatings : an investigation of the processing-microstructure-performance relationship AU - Cojocaru, C. V. AU - Lamarre, J.-M. AU - Legoux, J.-G. AU - Marple, B. R. AU - Lima, R. S. AU - Agarwal, A. AU - Hyland, M. M. AU - Lau, Y.-C. AU - Li, C.-J. AU - McDonald, A. AU - Toma, F.-L. T2 - Thermal Spray 2012 : Proceedings from the International Spray Conference T3 - International Thermal Spray 2012 Conference and Exposition (ITSC 2012), 21-24 May 2012, Houston, Texas, USA SP - 384 EP - 389 AB - Evaluating and understanding the relationship between processing, microstructure and performance of a dielectric coating is essential for its practical usage and reliable application. In this study, the role of the powder feedstock on the properties of atmospheric plasma sprayed forsterite (Mg2SiO4) dielectric coatings was investigated by using different forsterite powder cuts. The microstructural and porosity characteristics of the coatings associated with the spray conditions employed were assessed via scanning electron microscopy (SEM) and image analysis. The phase composition of the coatings was studied via X-ray diffraction and their crystallinity index determined. The electrical insulating characteristics were investigated using the dielectric breakdown test. The obtained electrical properties were correlated with the microstructural characteristics. Ultimately, a performance comparison between forsterite and other dielectric coatings tested in similar conditions is presented. DA - 2012/05/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0c7e9f80-69d6-48f6-9d9e-473622323dba ER - TY - JOUR TI - A laser thermal cycling rig as a new method to characterize the evolution of coating adhesion under thermal cycle AU - Poirier, D. AU - Irissou, E. AU - Legoux, J. G. AU - Lima, R. S. AU - Agarwal, A. AU - Hyland, M. M. AU - Lau, Y.-C. AU - Li, C.-J. AU - McDonald, A. AU - Toma, F.-L. T2 - Thermal Spray 2012 : Proceedings from the International Spray Conference T3 - International Thermal Spray 2012 Conference and Exposition (ITSC 2012), 21-24 May 2012, Houston, Texas, USA SP - 137 EP - 142 AB - Thermal sprayed coatings are often used for high temperature applications and, per se, are subjected to transient temperature gradients during operation. The recurrent temperature changes generate stresses that damage the coating with time, and can even lead to its delamination. The most common methods to evaluate coating behavior under thermal cycling are furnace testing or burner rigs. Both approaches cannot match the conditions reached in service for several applications, in term of the achievable heating rates for instance. As a consequence, a versatile and robust method to evaluate coating resistance to spalling under thermal cycles is still to be found. This paper presents the development of a thermal cycling rig where the heat input is provided by a laser. This rig allows easy testing of several samples jointly for heating rates as high as 55°C/s and for thousands of thermal cycles. Preliminary trials have allowed the development of different spalling criteria. Finally, it was found that SS430-based materials arc-sprayed on Al substrates exhibit higher delamination resistance (life) under rapid heating/cooling cycles than SS304 coatings on the same substrate. For such high heating rates, the thermal stresses generated in the coating would be more critical than the thermal mismatch at the interface coating/substrate. DA - 2012/05/21 PY - 2012 UR - http://www.asminternational.org/portal/site/www/AsmStore/ProductDetails/?vgnextoid=80aabe8b96d37310VgnVCM100000621e010aRCRD LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : aa4ecd7f-ab9e-406b-8e22-4bbe8ffb0cbf ER - TY - JOUR TI - HVOF coating case study for power plant process control ball valve application AU - Vernhes, Luc AU - Lee, David A. AU - Poirier, Dominique AU - Sapieha, Jolanta AU - Li, Duanjie AU - Lima, R. S. AU - Agarwal, A. AU - Hyland, M. M. AU - Lau, Y.-C. AU - Li, C.-J. AU - McDonald, A. AU - Toma, F.-L. T2 - Thermal Spray 2012 : Proceedings from the International Spray Conference T3 - International Thermal Spray 2012 Conference and Exposition (ITSC 2012), 21-24 May 2012, Houston, Texas, USA SP - 172 EP - 177 AB - This case study is the result of an investigation on HVOF Cr3C2-NiCr coating failure of on-off metal seated ball valve (MSBV) used in supercritical steam lines in a power plant and solution. HVOF Cr3C2-NiCr coating is used to protect thousands of MSBVs without incident. However, in this case the valves are challenged with exposure to rapid high pressure and temperature variation resulting in a unique situation where the coating experiences cracking and cohesive failure. A detailed investigation was undertaken by Velan, Kennametal Stellite, the National Research Council of Canada and the Ecole Polytechnique to determine possible failure cause and develop solutions in which highlights are presented. DA - 2012/05/21 PY - 2012 UR - http://www.asminternational.org/portal/site/www/AsmStore/ProductDetails/?vgnextoid=85babe8b96d37310VgnVCM100000621e010aRCRD#details LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 70b6125e-0493-4d00-a14d-800e068ca8df ER - TY - JOUR TI - Cold spray forming Inconel 718 AU - Wong, W. AU - Irissou, É. AU - Legoux, J.-G. AU - Bernier, F. AU - Vo, P. AU - Yue, S. AU - Michiyoshi, S. AU - Fukanuma, H. T2 - Thermal Spray 2012: Proceedings from the International Spray Conference and Exposition T3 - International Thermal Spray 2012 Conference and Exposition (ITSC 2012), May 21-24, 2012, Houston, Texas, USA SP - 243 EP - 248 AB - In this investigation, Inconel 718, a material known to cause nozzle clogging upon cold spraying, was cold spray formed to 6 mm-thick using the Plasma Giken cold spray system PCS- 1000. This was made possible due to the novel non-clogging nozzle material combined with a nozzle water cooling system. Coatings were as-spray formed using both nitrogen and helium as the propelling gasses. The resulting microstructures as well as the corresponding mechanical properties were studied. In addition, the effect of post-heat treatments was also investigated. It was found that for a given propelling gas used, the coating porosity level remained relatively similar (about 2.4% for nitrogen and 3.6% for helium) regardless of the coating treatment (as-sprayed or heat treated). Visual inspection from SEM micrographs showed a higher fraction of inter-particle metallurgical bonds for nitrogen gas sprayed coatings heat treated at 1250°C for 1 hour due to some sintering effect. This significantly affected its tensile properties with an average resulting ductility of 24.7%. DA - 2012/05/21 PY - 2012 UR - http://www.asminternational.org/search/-/journal_content/56/10192/CP2012ITSCCSP243/PUBLICATION LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c1af9ca4-47c1-4cc0-91b7-add039b3d759 ER - TY - JOUR TI - SPAEK-based binary blends and ternary composites as proton exchange membranes for DMFCs DO - 10.1016/j.memsci.2012.05.039 AU - Zhu, Ming AU - Song, Yang AU - Hu, Wei AU - Li, Xuefeng AU - Jiang, Zhenhua AU - Guiver, Michael D. AU - Liu, Baijun T2 - Journal of Membrane Science VL - 415-416 SP - 520 EP - 526 KW - Poly(aryl ether ketone); Protonexchangemembranes; Composites; Sol–gel, Fuel cells AB - Naphthalene-containing blendmembranes, comprising sulfonated polyaryletherketone (SPAEK) as the primary matrix, and basic component polyazomethine (PAM), which has a chemical structure partially similar with SPAEK, were investigated as protonexchangemembranes (PEMs). Further, a ternary-compositemembrane was successfully prepared by introducing acid-functionalized polysilsesquioxane (POSS–SO3H) into SPAEK/PAM composite using a sol–gel process. The relevant properties of the PEMs, such as proton conductivity, methanol permeability, water uptake, and morphology were determined, and it was shown that the ternary-compositemembrane, SPAEK/PAM/POSS–SO3H, showed a superior combination of properties for proton conductivity and methanol resistance. Its selectivity was 7.5 times higher than Nafion. DA - 2012/06/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 653f8ded-2ddb-4fdd-81d7-f1c3ecf243af ER - TY - JOUR TI - Modeling DME addition effects to fuel on PAH and soot in laminar coflow ethylene/air diffusion flames using two PAH mechanisms DO - 10.1080/00102202.2012.663989 AU - Liu, F AU - Dworkin, S. B. AU - Thomson, M. J. AU - Smallwood, G. J. T2 - Combustion Science and Technology T3 - Seventh Mediterranean Combustion Symposium, Sept. 11-15, 2011, Chia Laguana, Sardinia, Italy VL - 184 IS - 7-8 SP - 966 EP - 979 KW - bimethyl ether addition; laminar diffusion flame; Soot and PAH formation; synergistic effect AB - Effects of dimethyl ether (DME) addition to fuel on polycyclic aromatic hydrocarbons (PAH) and soot formation in laminar coflow ethylene/air diffusion flames were revisited numerically. Calculations were conducted using two gas-phase reaction mechanisms with PAH formation and growth: one is the C2 chemistry of the Appel, Bockhorn, and Frenklach (ABF) mechanism with PAH growth up to A4 (pyrene); the other is also a C2 chemistrymechanism newly developed at the German Space Center (DLR) with PAH growth up to A5 (corannulene). Soot was modeled based on the assumptions that soot inception is due to the collision of two pyrene molecules, and soot surface growth and oxidation follow a hydrogen abstraction carbon addition (HACA) sequence. The DLR mechanism predicted much higher concentrations of pyrene than the ABF mechanism. A much smaller value of α in the surface growth model associated with the DLR mechanism must be used to predict the correct peak soot volume fraction. Both reaction mechanisms are capable of predicting the synergistic effect of DME addition to fuel on PAH formation. The locations of high PAH concentrations predicted by the DLR mechanism are in much better agreement with available experimental observations. A weak synergistic effect of DME addition on soot formation was predicted by the ABF mechanism. The DLR mechanism failed to predict the synergistic effect on soot. The likely causes for such a failure and the implications for future research on soot inception and surface growth were discussed. DA - 2012/08/03 PY - 2012 PB - Taylor and Francis LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2958d67e-04e4-4fc2-83e7-6e94594c3e4f ER - TY - JOUR TI - Copper tungstate thin-films for nitric oxide sensing DO - 10.1016/j.snb.2012.06.067 AU - Gonzalez, C. M. AU - Du, X. AU - Dunford, J. L. AU - Post, M. L. T2 - Sensors and Actuators B: Chemical VL - 173 SP - 169 EP - 176 KW - Electrochemical sensors; Conductometric sensors; Gas sensors; NOx sensors; Gas-phase pollutants; Environment monitoring technologies; Thin-films; Semiconducting metal-oxides AB - CuWO4 thin-films prepared by the pulsed laser deposition technique were studied for monitoring nitric oxide (NO) in the concentration range of 10 < [NO] < 400 ppm under synthetic air. The thin-film films were characterized by X-ray diffraction (XRD), depth-profilometry and electron transport measurements. The CuWO4 thin-film response to O2 confirmed an n-type conductivity. Monitoring the thin-film conductometric response to NO at both 300 and 500 °C revealed the operation of a temperature-dependent mechanism for detection. At 300 °C, increasing [NO] produced a consistent increment in thin-film resistance, while at 500 °C the thin-film resistance decreased with [NO]. At 500 °C, a transient response was systematically observed. The chemical origin of the transient is discussed. The estimation of response factors to NO exposure in the presence of high [O2] indicates a significantly higher selectivity to NO. Extensive conductometric measurements show that the thin-films feature good electronic and thermal stability over time. DA - 2012/07/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 91216a28-404e-4d8c-809a-1dc56372b15f ER - TY - JOUR TI - Polysulfones with phenylalanine derivatives as chiral selectors – membranes for chiral separation DO - 10.6000/1929-6037.2012.01.01.1 AU - Isezaki, Jun AU - Yoshikawa, Masakazu AU - Li, Nanwen AU - Robertson, Gilles P. AU - Guiver, Michael D. T2 - Journal of Membrane and Separation Technology VL - 1 IS - 1 SP - 1 EP - 8 KW - Chiral separation, membrane, optical resolution, permselectivity, polysulfone AB - Polysulfone with a derivative of phenylalanyl residue as a chiral selector (PSf-Ac-D-Phe or PSf-Ac-L-Phe) were prepared by polymer reaction of benzylamine-modified polysulfones with N-a-acetyl-D-phenylalanine or N-a-acetyl-L-phenylalanine. Both polysulfones having a chiral selector gave durable self-standing membranes. The specific rotations of those polymers revealed that the chiral selectors were successfully introduced into the polysulfone. PSf-Ac-D-Phe membrane incorporated L-Glu in preference to D-Glu and vice versa. The chiral separation ability was studied by applying a concentration gradient as a driving force for membrane transport. Permselectivities for those two types of membrane reflected their adsorption selectivities. PSf-Ac-D-Phe membrane selectively transported L-Glu and vice versa. Predicted permselectivities by adopting membrane resistance coincided with the observed ones. DA - 2012/10/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b4ec4944-5b88-4c4a-90a0-83ba1d30251c ER - TY - JOUR TI - Prétraitement des résidus de la collecte à 3 voies pour améliorer leur biométhanisation AU - Frigon, J.-C. AU - Guiot, S. R. AU - Barnabé, S. AU - Adjallé, K. D. AU - Moreau, A. AU - Camirand, É. T2 - Vecteur environnement VL - 45 IS - 4 SP - 54 EP - 60 DA - 2012/09/01 PY - 2012 LA - fra C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 66501ae1-87bc-4cb5-bbae-eb35f91f2d41 ER - TY - JOUR TI - Sorption of 2,4-dinitroanisole (DNAN) on lignin DO - 10.1016/S1001-0742(11)60863-2 AU - Saad, Rabih AU - Radovic-Hrapovic, Zorana AU - Ahvazi, Behzad AU - Thiboutot, Sonia AU - Ampleman, Guy AU - Hawari, Jalal T2 - Journal of Environmental Sciences VL - 24 IS - 5 SP - 808 EP - 813 KW - sorption; DNAN; lignin; kinetics; isotherms AB - The present study describes the use of two commercially available lignins, namely, alkali and organosolv lignin, for the removal of 2,4-dinitroanisole (DNAN), a chemical widely used by the military and the dye industry, from water. Sorption of DNAN on both lignins reached equilibrium within 10 hr and followed pseudo second-order kinetics with sorption being faster with alkali than with organosolv lignin, i.e. k2 10.3 and 0.3 g/(mg·hr), respectively. In a separate study we investigated sorption of DNAN between 10 and 40C and found that the removal of DNAN by organosolv lignin increased from 0.8 to 7.5 mg/g but reduced slightly from 8.5 to 7.6 mg/g in the case of alkali lignin. Sorption isotherms for either alkali or organosolv lignin best fitted Freundlich equation with enthalpy of formation, ΔH0 equaled to 14 or 80 kJ/mol. To help understand DNANsorption mechanisms we characterized the twolignins by elemental analysis, BET nitrogen adsorption-desorption and 31P NMR. Variations in elemental compositions between the twolignins indicated that alkali lignin should have more sites (O- and S-containing functionalities) for H-bonding. The BET surface area and calculated total pore volume of alkali lignin were almost 10 times greater than that of organosolv lignin suggesting that alkali lignin should provide more sites for sorption. 31P NMR showed that organosolv lignin contains more phenolic -OH groups than alkali lignin, i.e., 70% and 45%, respectively. The variations in the type of OH groups between the twolignins might have affected the strength of H-bonding between DNAN and the type of lignin used. DA - 2012/05/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 097f51b8-5369-4ffa-86e7-eb41f0d433f6 ER - TY - JOUR TI - Sub-inhibitory concentrations of different pharmaceutical products affect the meta-transcriptome of river biofilm communities cultivated in rotating annular reactors DO - 10.1111/j.1758-2229.2012.00341.x AU - Yergeau, Étienne AU - Sanschagrin, Sylvie AU - Waiser, Marley J. AU - Lawrence, John R AU - Greer, Charles W. T2 - Environmental Microbiology Reports VL - 4 IS - 3 SP - 350 EP - 359 AB - Surface waters worldwide are contaminated by pharmaceutical products that are released into the environment from wastewater treatment plants. Here, we hypothesize that pharmaceutical products have effects on organisms as well as genes related to nutrient cycling in complex microbial communities. To test this hypothesis, biofilms were grown in reactors and subjected low concentrations of three antibiotics [erythromycin, ER, sulfamethoxazole, SL and sulfamethazine, SN) and a lipid regulator (gemfibrozil, GM). Total community RNA was extracted and sequenced together with PCR amplicons of the 16S rRNA gene using 454 pyrosequencing. Exposure to pharmaceutical products resulted in very little change in bacterial community composition at the phylum level based on 16S rRNA gene amplicons, even though some genera were significantly affected. In contrast, large shifts were observed in the active community composition based on taxonomic affiliations of mRNA sequences. Consequently, expression of gene categories related to N, P and C cycling were strongly affected by the presence of pharmaceutical products, with each treatment having specific effects. These results indicate that low pharmaceutical product concentrations rapidly provoke a variety of functional shifts in river bacterial communities. In the longer term these shifts in gene expression and microbial activity could lead to a disruption of important ecosystem processes like nutrient cycling. DA - 2012/06/01 PY - 2012 PB - Society for Applied Microbiology and Blackwell Publishing Ltd LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9c10e26c-8c49-48d8-84a3-dbc4c2d484dd ER - TY - JOUR TI - The performance of a thermophilic microbial fuel cell fed with synthesis gas DO - 10.1016/j.enzmictec.2012.05.008 AU - Hussain, A. AU - Mehta, P. AU - Raghavan, V. AU - Wang, H. AU - Guiot, S. R. AU - Tartakovsky, B. T2 - Enzyme and Microbial Technology VL - 51 IS - 3 SP - 163 EP - 170 KW - MFC; Synthesis gas; Carbon monoxide; Thermophilic conditions AB - This study demonstrated electricity generation in a thermophilic microbial fuel cell (MFC) operated on synthesis gas (syngas) as the sole electron donor. At 50 °C, a volumetric power output of View the MathML source and a syngas conversion efficiency of 87–98% was achieved. The observed pathway of syngas conversion to electricity primarily consisted of a two-step process, where the carbon monoxide and hydrogen were first converted to acetate, which was then consumed by the anodophilic bacteria to produce electricity. A denaturing gradient gel electrophoresis (DGGE) analysis of the 16S rDNA revealed the presence of Geobacter species, Acetobacter, methanogens and several uncultured bacteria and archaea in the anodic chamber. DA - 2012/05/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d547efcc-11dd-4403-9bc4-b8268ec5cbf9 ER - TY - JOUR TI - Microbial fuel cell operation with intermittent connection of the electrical load DO - 10.1016/j.jpowsour.2012.02.010 AU - Grondin, F. AU - Perrier, M. AU - Tartakovsky, B. T2 - Journal of Power Sources VL - 208 SP - 18 EP - 23 KW - MFC; External resistance; Intermittentconnection; Duty cycle AB - Laboratory-scale microbialfuelcells are often operated with a constant electricalload. Meanwhile, variations in influent strength and quality, as well as the processes of biofilm growth and decay lead to significant changes of the MFC internal resistance over time. This inevitably results in a mismatch between the internal and the external resistances therefore decreasing MFC power output. This study presents the concept of MFC operation with intermittentconnection of the electricalload (external resistance). The efficiency of the proposed method is demonstrated by MFC operation with external resistances significantly below the MFC internal resistance and comparing power outputs obtained using either constant or intermittently connected resistances. DA - 2012/02/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2de88b9f-b822-4d64-bab2-93fa7f820f88 ER - TY - JOUR TI - Evolution of space charges and conductivity with DC aging of polyethylene-synthetic and natural clay-composites AU - Abou-Dakka, Mahmoud T2 - Journal of Nanomaterials SN - 1687-4110 VL - IS - KW - polypropylene nano-composites (PNC); dc field conductivity; space charge evolution; PEA technique; natural and synthetic organoclay AB - To develop new materials with better dielectric properties for electric equipment, such as power capacitors, two types of polypropylene (PP)-based nanocomposites (PNC) were manufactured. The PNCs were composed of PP with different concentrations of synthetic and natural organoclays. The evolution of the space charge density and dc conductivity with dc poling of these composites were investigated. It was observed that the optimal concentration of nanofillers for space charge mitigation with aging time was 2-wt% for PP-natural clay composite and between 2 and 4 wt% for the PP-synthetic clay. Above these percentages, charge transport through overlapping of nanoparticles can occur. This fact is due to the interaction zone of double layers formed at the nanoparticle/host material interfaces. Under dc field the overlapping increases the conductivity of polymer nanocomposite (PNC), which could reduce the benefit of incorporating nanofillers into PP. The total charge stored in unfilled PP increased continuously with time, reaching a maximum around 5000 h before decreasing. However, the total charges in all filled specimens only changed slightly. The effect of platelet size on space charge mitigation reported by other authors is confirmed here, i.e. nanofillers with smaller platelets such as natural clay can mitigate space charge more efficiently than nanofillers with larger platelets such as synthetic clay. The conductivity with -25 kV/mm dc field of the specimens containing 6-wt% of natural clay and 8-wt% of synthetic clay reached ≈ 6 times the level for unfilled PP. This observation could be related to crossing the percolation threshold of these composites. At least 1000 h of aging with -25 kV/mm dc field is required before correctly evaluating the impact of filling the PP with nano-particles. DA - 2012/11 PY - 2012 PB - Hindawi LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9a96cb74-ab02-4a37-910d-e96762e3bddc ER - TY - JOUR TI - Characterization of Zn-containing metal–organic frameworks by solid-state 67Zn NMR spectroscopy and computational modeling DO - 10.1002/chem.201201563 AU - Sutrisno, Andre AU - Terskikh, Victor V. AU - Shi, Qi AU - Song, Zhengwei AU - Dong, Jinxiang AU - Ding, San Yuan AU - Wang, Wei AU - Provost, Bianca R. AU - Daff, Thomas D. AU - Woo, Tom K. AU - Huang, Yining T2 - Chemistry : a European Journal VL - 18 IS - 39 SP - 12251 EP - 12259 KW - desolvation; host–guest systems; metal–organic frameworks; NMR spectroscopy; solid-state structures; zinc AB - Metal–organic frameworks (MOFs) are an extremely important class of porous materials with many applications. The metal centers in many important MOFs are zinc cations. However, their Zn environments have not been characterized directly by 67Zn solid-state NMR (SSNMR) spectroscopy. This is because 67Zn (I=5/2) is unreceptive with many unfavorable NMR characteristics, leading to very low sensitivity. In this work, we report, for the first time, a 67Zn natural abundance SSNMR spectroscopic study of several representative zeolitic imidazolate frameworks (ZIFs) and MOFs at an ultrahigh magnetic field of 21.1 T. Our work demonstrates that 67Zn magicangle spinning (MAS) NMR spectra are highly sensitive to the local Zn environment and can differentiate nonequivalent Zn sites. The 67Zn NMR parameters can be predicted by theoretical calculations. Through the study of MOF-5 desolvation, we show that with the aid of computational modeling, 67Zn NMR spectroscopy can provide valuable structural information on the MOF systems with structures that are not well described. Using ZIF-8 as an example, we further demonstrate that 67Zn NMR spectroscopy is highly sensitive to the guest molecules present inside the cavities. Our work also shows that a combination of 67Zn NMR data and molecular dynamics simulation can reveal detailed information on the distribution and the dynamics of the guest species. The present work establishes 67Zn SSNMR spectroscopy as a new tool complementary to X-ray diffraction for solving outstanding structural problems and for determining the structures of many new MOFs yet to come. DA - 2012/09/03 PY - 2012 PB - Wiley LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9fcc2fd1-9ea4-4af8-8efa-dbe4026270af ER - TY - JOUR TI - Solid-state (73) Ge NMR spectroscopy of simple organogermanes DO - 10.1002/chem.201201944 AU - Hanson, Margaret A. AU - Sutrisno, Andre AU - Terskikh, Victor V. AU - Baines, Kim M. AU - Huang, Yining T2 - Chemistry : a European Journal VL - 18 IS - 43 SP - 13770 EP - 13779 KW - density functional calculations; germanium; NMR spectroscopy AB - Germanium-73 is an extremely challenging nucleus to examine by NMR spectroscopy due to its unfavorable NMR properties. Through the use of an ultrahigh (21.1 T) magnetic field, a systematic study of a series of simple organogermanes was carried out. In those cases for which X-ray structural data were available, correlations were drawn between the NMR parameters and structural metrics. These data were combined with DFT calculations to obtain insight into the structures of several compounds with unknown crystal structures. DA - 2012/09/28 PY - 2012 PB - Wiley LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 55c26536-1113-45a0-a538-68813956e421 ER - TY - JOUR TI - Identification of volatile iron species generated by UV photolysis DO - 10.1016/j.microc.2012.05.036 AU - Grinberg, Patricia AU - Sturgeon, Ralph E. AU - Gardner, Graeme T2 - Microchemical Journal SN - 0026-265X VL - 105 SP - 44 EP - 47 KW - volatile metal species; vapor generation; iron; iron pentacarbonyl; GC-MS; silylation AB - The volatile products of photochemical generation (PVG) of iron from solutions of formic and acetic acids were examined by GC-MS. Iron pentacarbonyl was the sole analytical species detected in both cases, as confirmed by comparison of the results with a NIST reference spectrum. Silylation of the interior surfaces of the quartz tubing comprising the photochemical reactor essentially eliminated memory effects such that signal duration was determined simply by the residence time of the sample solution. DA - 2012/11 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f69e7613-d062-444d-88a2-0a3e7f057154 ER - TY - JOUR TI - Systematic shift evaluation of the NRC 88Sr+ single-ion optical frequency standard to a few parts in 10^-17 DO - 10.1109/FCS.2012.6243672 AU - Dubé, P. AU - Madej, A. A. AU - Bernard, J. E. AU - Zhou, Z. T2 - 2012 IEEE International Frequency Control Symposium T3 - 2012 IEEE International Frequency Control Symposium (FCS), 21-24 May 2012, Baltimore, MD, USA SN - 1075-6787 SN - 978-1-4577-1821-2 SP - 1 EP - 6 AB - A new strontium ion trap of the endcap design was built recently at the National Research Council of Canada for better control of the micromotion shifts. The uncertainty caused by these shifts has been reduced by more than four orders of magnitude compared to the original NRC trap, down to a level of ≈ 10-18. In this paper we discuss the evaluation of micromotion shifts and of several other sources of importance to optical frequency standards based on single ions. The total fractional frequency uncertainty of the new strontium ion trap system is estimated to be ≈ 2 × 10-17, limited by the blackbody radiation shift. A preliminary measurement of the clock transition frequency with a fractional uncertainty of 2×10-15, limited by the accuracy of the maser reference, is also presented. DA - 2012/07/19 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4211a72d-6dcd-46f6-aceb-3d078f741a42 ER - TY - JOUR TI - Peptide sequencing challenge DO - 10.1007/s00216-012-6192-3 AU - Meija, Juris T2 - Analytical and Bioanalytical Chemistry SN - 1618-2642 VL - 404 IS - 4 SP - 931 EP - 932 DA - 2012/09 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 36e26c65-810c-41ed-98ce-dc4a59819b57 ER - TY - JOUR TI - An improved current-comparator-based power standard with an uncertainty of 2.5 uW/VA (k=1) AU - So, Eddy AU - Arseneau, Rejean AU - Angelo, Dave T2 - IEEE Transactions on Instrumentation and Measurement - Special Issue T3 - 2012 Conference on Precision Electromagnetic Measurements (CPEM), 1-6 July 2012, Washington DC KW - current-comparator; power bridge; power standard; uncertainty AB - An improved standard derived from a current power bridge for calibrating active/reactive power and energy meters under sinusoidal conditions is described. Measurements can be made at any power factor from zero lag through unity to zero lead, positive or negative power, at 120 V,5 A, and 50 or 60 Hz. The improved power standard has an estimated uncertainty of not more than 2.5 uW/VA at k=1. Special high accuracy current and voltage range extenders have been incorporated to extend the current and voltage ranges up to 200 A and 1200 V, respectively. DA - 2012/07/06 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 27b197e3-e8c8-4040-b9fa-91f47a49a5d9 ER - TY - JOUR TI - Determination of amino acids in selenium-enriched yeast by gas chromatography–mass spectrometry after microwave assisted hydrolysis DO - 10.1016/j.aca.2012.07.011 AU - Zhang, Xu AU - Yang, Lu AU - Mester, Zoltan T2 - Analytica Chimica Acta SN - 0003-2670 VL - 744 SP - 54 EP - 59 KW - amino acids; microwave-irradiation hydrolysis; gas chromatography–mass spectrometry; selenium enriched yeast AB - A simple, rapid microwave digestion procedure for protein hydrolysis preceding the determination of amino acids in yeast using gas chromatography–mass spectrometry (GC–MS) is described. Protein hydrolysis was performed in a focused microwave using 4 M methanesulfonic acid (MAS). Amino acids were derivatized with methyl chlorofomate (MCF) and extracted into chloroform prior to GC–MS analysis. The microwave parameters, including power, temperature and heating time, were optimized. It was found that temperature and heating time were the most influential factors. A total of 17 amino acids were determined in selenium-enriched yeast with use of standard addition calibration. Limits of detection and quantitation (LODs/LOQs) of the amino acids measured were in the sub-nmol range, suitable for monitoring of amino acids in yeast and other food products. DA - 2012/07/16 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3d6fbe56-ee1d-4dfd-b454-d8eb1c294138 ER - TY - JOUR TI - Ontology fusion in high-level-architecture-based collaborative engineering environments DO - 10.1109/TSMCA.2012.2190138 AU - Sun, Hongbo AU - Fan, Wenhui AU - Shen, Weiming AU - Xiao, Tianyuan T2 - IEEE Transactions on Systems, Man, and Cybernetics, Part A: Systems And Humans SN - 1083-4427 VL - PP IS - 99 SP - 1 EP - 12 KW - collaborative engineering environments (CEEs), high-level architecture (HLA), ontology, product development AB - In high-level-architecture (HLA)-based distributed heterogeneous collaborative engineering environments (CEEs), the construction of federation object model files is time consuming. This paper presents an ontology fusion approach aiming at establishing a common understanding in such collaborative environments. The proposed approach has three steps: ontology mapping, ontology alignment, and ontology merging. Ontology mapping employs a top-down approach to explore all bridge relations between two terms from different ontologies based on bridge axioms and deduction rules. Ontology alignment adopts a bottom-up approach to discover implicit bridge relations between two terms from different domain ontologies based on equivalent inference. Ontology merging generates a new collaboration ontology from discovered equivalent bridge relations. It adopts an axiom-based ontology fusion strategy and takes heavy-weighted ontologies into consideration. It can find all the explicit and derived interontology relations. In a typical CEE, the proposed approach has a great potential to improve the efficiency of preparation for HLA-based collaborative engineering processes, reduce the work load for adaptive adjustment of existing platforms, and enhance the reusability and flexibility of CEEs. A case study has been conducted to validate the feasibility of the proposed approach. DA - 2012/05/01 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 17ce76dc-5f37-49c4-8418-64eff96f74da ER - TY - JOUR TI - Frame-based ontological view for semantic integration DO - 10.1016/j.jnca.2011.02.010 AU - Xue, Yunjiao AU - Ghenniwa, Hamada H. AU - Shen, Weiming T2 - Journal of Network and Computer Applications SN - 1084-8045 VL - 35 IS - 1 SP - 121 EP - 131 KW - semantic integration; ontology; ontologicalview; frame; specification language AB - Semantic integration is crucial for successful collaboration between heterogeneous information systems. Traditional ontology-driven approaches rely on the availability of explicit ontologies. However, in most application domains, this prerequisite cannot be met. In order to address this issue, this paper investigates the theoretical foundation of ontologies and extends the traditional ontology concept to an ontologicalview concept. To explicitly and formally specify the ontologicalviews, a Frame-basedOntologicalview Specification Language (FOSL) is proposed. This language is based on the frame knowledge representation paradigm and uses XML as the encoding. The ontologicalview driven semanticintegration can be achieved based on the specifications. A proof-of-concept prototype environment has been implemented to achieve semanticintegrationbased on ontologicalviews specified with FOSL. DA - 2012/01/01 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f82adcce-bbcb-4d87-9837-f7d6c433ee70 ER - TY - JOUR TI - Ontology-based interoperation model of collaborative product development DO - 10.1016/j.jnca.2011.02.012 AU - Sun, Hongbo AU - Fan, Wenhui AU - Shen, Weiming AU - Xiao, Tianyuan T2 - Journal of Network and Computer Applications SN - 1084-8045 VL - 35 IS - 1 SP - 132 EP - 144 KW - collaborative product development; HLA - high level architecture; ontology AB - The reuse of existing systems is an important objective of HLA (High Level Architecture)-based collaborative product development systems. However, in order to reuse an existing system, its interoperation interface has to be modified to comply with the objective and interaction representations defined in a corresponding FOM (Federation Object Model). Such modifications imply added time and effort, which diminishes the efficiency of system reuse in collaborative product development. This paper presents a heavy-weighted ontology-based construction method for interoperation models to support the reuse of subsystems in various collaborative contexts. In this method ontologies are used to specify the semantics of object classes and interaction classes in subsystems in a formal and computer readable fashion. In doing so, a FCA (Formal Concept Analysis) -like construction method is introduced to establish the original interoperation ontology from scratch. An automatic transforming method from a SOM (Simulation Object Model) into interoperation ontology is also described to make it easy for existing HLA-based systems to adopt this approach. Then a consistency verification method is introduced to guarantee the consistency of the interoperation ontologies. A case study is used to demonstrate the feasibility of the proposed method. As a human- friendly modeling method, compared with existing interoperation modeling methods, the proposed method is more flexible, efficient and reliable. DA - 2012/01/01 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 99986c53-40c3-4b1c-bc00-3a9555f5ec56 ER - TY - JOUR TI - Exchange bias in a nanocrystalline hematite/permalloy thin film investigated with polarized neutron reflectometry DO - 10.1103/PhysRevB.86.054408 AU - Cortie, D. L. AU - Lin, K.-W. AU - Shueh, C. AU - Hsu, H.-F. AU - Wang, X. L. AU - James, M. AU - Fritzsche, H. AU - Bruck, S. AU - Klose, F. T2 - Physical Review B: condensed matter and materials physics VL - 86 IS - 5 SP - 054408-1 EP - 054408-10 AB - We investigated a hematite α-Fe2O3/permalloy Ni80Fe20 bilayer film where the antiferromagnetic layer consisted of small hematite grains in the 2 to 16 nm range. A pronounced exchange bias effect occurred below the blocking temperature of 40 K. The magnitude of exchange bias was enhanced relative to reports for identical compounds in large grain, epitaxial films. However, the blocking temperature was dramatically reduced. As the Néel temperature of bulk α-Fe2O3 is known to be very high (860 K), we attribute the low-temperature onset of exchange bias to the well-known finite-size effect which suppresses the Morin transition for nanostructured hematite. Polarized neutron reflectometry was used to place an upper limit on the concentration and length scale of a layer of uncompensated moments at the antiferromagnetic interface. The data were found to be consistent with an induced magnetic region at the antiferromagnetic interface of 0.5–1.0 μB per Fe atom within a depth of 1–2 nm. The field dependence of the neutron spin-flip signal and spin asymmetry was analyzed in the biased state, and the first and second magnetic reversal were found to occur by asymmetric mechanisms. For the fully trained permalloy loop, reversal occurred symmetrically at both coercive fields by an in-plane spin rotation of ferromagnetic domains. DA - 2012/08/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 85b2dcec-425d-41de-9dcf-e9133bd25ee7 ER - TY - JOUR TI - Performance of Cu-coated vanadium cans for in situ neutron powder diffraction experiments on hydrogen storage materials DO - 10.1107/S002188981202938X AU - Flacau, Roxana AU - Bolduc, Jim AU - Bibienne, Thomas AU - Huot, Jacques AU - Fritzsche, Helmut T2 - Journal of Applied Crystallography VL - 45 IS - 5 SP - 902 EP - 905 AB - In situ neutron powder diffraction (NPD) measurements of hydrogenation processes taking place at high temperatures pose difficulties related to the choice of sample can material. This article describes a simple design for a copper-coated vanadium can and its connection to the gas-handling system, tested up to 523 K. High-quality NPD patterns of TiV1.2Mn0.8 body-centred cubic alloy, as-cast and partially hydrogenated, were collected at 373 K and deuterium pressures up to 2 bar (200 kPa). DA - 2012/08/09 PY - 2012 PB - Wiley LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f5c43965-9a75-4b1b-884d-3fefb8cb52e9 ER - TY - JOUR TI - Efficient image recognition using local feature and fuzzy triangular number based similarity measures DO - 10.4156/IJEI.vol3.issue1.5 AU - Belacel, Nabil AU - Kardouchi, Mustapha AU - Liu, Zikuan T2 - International Journal of Engineering and Industries VL - 3 IS - 1 SP - 45 EP - 54 AB - Image local scale invariant features are of great importance for object recognition. Among various local scale invariant feature descriptors, Scale Invariant Feature Transform (SIFT) descriptor has been shown to be the most descriptive one and thus widely applied to image retrieval, object recognition and computer vision. By SIFT descriptor, an image may be described by hundreds of key points with each point depicted by a 128-element feature vector; this representation makes the subsequent feature matching very computationally demanding. In this paper, we propose to incorporate the fuzzy set concepts into SIFT features and define fuzzy similarity between images. The proposed approach is applied to image recognition. Experimental results with the coil-100 image database are provided to show the superiority of the proposed approach. DA - 2012/03/01 PY - 2012 PB - Advanced Institute of Convergence IT LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6d74bcd1-600b-4472-8c5c-1d7bf8ea5784 ER - TY - JOUR TI - PSOA2TPTP: a reference translator for interoperating PSOA RuleML with TPTP reasoners DO - 10.1007/978-3-642-32689-9_22 AU - Zou, Gen AU - Peter-Paul, Reuben AU - Boley, Harold AU - Riazanov, Alexandre T2 - Rules on the Web: Research and Applications - Proceedings of the 6th International Symposium on Rules, RuleML 2012 T2 - Lecture Notes in Computer Science; 7438 T3 - RuleML2012 - The 6th International Symposium on Rules, August 27-29, 2012, Montpellier, France SN - 0302-9743 SN - 978-3-642-32688-2 SN - 978-3-642-32689-9 SP - 264 EP - 279 AB - PSOA RuleML is a recently specified rule language combining relational and object-oriented modeling. In order to provide reasoning services for PSOA RuleML, we have implemented a reference translator, PSOA2TPTP, to map knowledge bases and queries in the PSOA RuleML presentation syntax (PSOA/PS) to the popular TPTP format, supported by many first-order logic reasoners. In particular, PSOA RuleML reasoning has become available using the open-source VampirePrime reasoner, enabling query answering and entailment as well as consistency checking. The translator, currently composed of a lexer, a parser, and tree walkers, is generated by the ANTLR v3 parser generator tool from the grammars we developed. We discuss how to rewrite the original PSOA/PS grammar into an LL(1) grammar, thus demonstrating that PSOA/PS can be parsed efficiently. We also present a semantics-preserving mapping from PSOA RuleML to TPTP through a normalization and a translation phase. We wrap the translation and querying code into RESTful Web services for convenient remote access and provide a demo Web site. DA - 2012/08/29 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : de5acf87-0778-4f67-a397-cebb25b2c1b2 ER - TY - JOUR TI - A heterogeneous sensors integration platform for independent living spaces DO - 10.1109/CSCWD.2012.6221882 AU - Zheng, Cheng AU - Shen, Weiming AU - Xue, Henry AU - Hao, Qi T2 - Proceedings of the 2012 IEEE 16th International Conference on Computer Supported Cooperative Work in Design (CSCWD 2012) T3 - 16th International Conference on Computer Supported Cooperative Work in Design (CSCWD 2012), 23-25 May 2012, Wuhan, China SN - 978-1-4673-1212-7 SP - 616 EP - 621 KW - independent living spaces; cross-language services; Apache Thrift; sensors integration; COTS sensors and devices; data collection AB - Continual advances in modern technologies make it feasible to build intelligent independent living spaces for the elderly and disabled. In the past few years, various sensors and medical devices have been commercially available for home healthcare applications, but still there is a lack of effort on integrating heterogeneous commercial off-the-shelf (COTS) sensors from various vendors to collect data and provide more flexibility in product selection for customers. In order to address this issue, this paper presents a heterogeneous sensors integration platform for independent living spaces. The proposed platform, which is based on Apache Thrift, can accomplish the tasks of data collection, organization, and storage through cross-language services. A prototype system has been implemented and integrated into an independent living space monitoring system to validate the proposed approach. DA - 2012/06/21 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a3d962b9-6c5d-48dc-a4a1-dcfb982dc09d ER - TY - JOUR TI - Security and privacy considerations for wireless sensor networks in smart home environments DO - 10.1109/CSCWD.2012.6221884 AU - Islam, Kamrul AU - Shen, Weiming AU - Wang, Xianbin T2 - Proceedings of the 2012 IEEE 16th International Conference on Computer Supported Cooperative Work in Design (CSCWD 2012) T3 - 16th International Conference on Computer Supported Cooperative Work in Design (CSCWD 2012), 23-25 May 2012, Wuhan, China SN - 978-1-4673-1212-7 SP - 626 EP - 633 KW - wireless sensor networks KW - smart home KW - privacy KW - security KW - cryptography AB - Wireless Sensor Network (WSN) has emerged as a dependable technology to improve the quality of life in smart homes through offering various automated, interactive and comfortable services. Sensors integrated at different places in homes, offices, and even in clothes, equipment, and utilities are used to sense and monitor occupants' positions, movements, vital signs, utility usage, temperature and humidity levels of rooms, etc. Along with sensing and monitoring capabilities, sensors cooperate and communicate with themselves to deliver, share and process sensed information and assist real-time decisionmaking procedures through triggering appropriate alerts and actions. However, ensuring privacy and providing adequate security in these crucial services provided by WSNs is a major issue in smart home environments. In this paper, we examine the privacy and security challenges of WSNs and survey its practicality for smart home environments. We discuss the unique characteristics that distinguish a smart environment from the rest, elaborate on security and privacy issues and their respective solution measures. A number of challenges and interesting research issues emerging from this study have been reported for further investigation. DA - 2012/06/21 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2f6e99ba-2d7e-4af4-a79f-e65e9cd9950f ER - TY - CHAP TI - PSOA RuleML API : a tool for processing abstract and concrete syntaxes DO - 10.1007/978-3-642-32689-9_23 AU - Al Manir, Mohammad Sadnan AU - Riazanov, Alexandre AU - Boley, Harold AU - Baker, Christopher J. O. T2 - Rules on the Web: Research and Applications the 6th International Symposium, RuleML 2012 Proceedings T2 - Lecture Notes In Computer Science; 7438 T3 - 6th International Symposium on Rules (RuleML 2012), August 27-29, 2012, Montpellier, France SN - 0302-9743 SN - 978-3-642-32688-2 SN - 978-3-642-32689-9 SP - 280 EP - 288 AB - PSOA RuleML is a rule language which introduces positionalslotted, object-applicative terms in generalized rules, permitting relation applications with optional object identifiers and positional or slotted arguments. This paper describes an open-source PSOA RuleML API, whose functionality facilitates factory-based syntactic object creation and manipulation. The API parses an XML-based concrete syntax of PSOA RuleML, creates abstract syntax objects, and uses these objects for translation into a RIF-like presentation syntax. The availability of such an API will benefit PSOA rule-based research and applications. DA - 2012/08/29 PY - 2012 PB - Springer Berlin Heidelberg LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b78382ac-757a-4514-8661-8533f170e621 ER - TY - JOUR TI - Transcending the display size: the case for speech interaction in educational applications AU - Munteanu, Cosmin T2 - CHI 2012: ACM SIGCHI Conference on Human Factors in Computing Systems T3 - ACM SIGCHI Conference on Human Factors in Computing Systems (CHI 2012), May 5-10, 2012, Austin, Texas, U.S.A. SN - 978-1-4503-1016-1/12/05 SP - 1 EP - 4 KW - Educational interfaces; automatic speech recognition; interface design; multimodal interaction AB - Speech is the most natural form of communication that humans employ, and is one of the main modalities through which we acquire and share knowledge. Moreover, speech is used not only to deliver knowledge, but as a modality that supports learning, such as student-teacher interactions around printed materials. During the past decade, we have witnessed significant advances mainly in preserving spoken educational materials, from informal how-to videos to full academic lectures being stored and available through a variety of online channels. Unfortunately, there is proportionately less research on enabling access to such multimedia knowledge repositories (e.g. searching, indexing) or on facilitating spoken, natural interaction between learners and digital interactive media (such as automated tutors or interactive learning resources). By enabling speech as a modality, learners become less constrained by the physical properties of the educational materials and can interact more naturally with the educational software, be it in the form of a mobile language assistant, a desktop-based online lecture browsing system, or a mixed-reality serious gaming system. In this paper I present examples of such recent research on improving the way we interact with educational resources through speech and natural language, and make the case for the need to conduct further research in this area. DA - 2012/05/10 PY - 2012 PB - ACM LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 74752860-ba91-4e0f-b72c-a901d33bb5eb ER - TY - JOUR TI - Towards conservative helicopter loads prediction using computational intelligence techniques DO - 10.1109/IJCNN.2012.6252624 AU - Valdes, Julio J. AU - Cheung, Catherine AU - Li, Matthew T2 - Proceedings of the IEEE 2012 World Congress on Computational Intelligence, IEEE 2012 International Joint Conference on Neural Networks T3 - IEEE 2012 International Joint Conference on Neural Networks (IJCNN 2012), June 10-15, 2012, Brisbane, Australia SN - 978-1-4673-1489-3 SP - 1 EP - 8 AB - Airframe structural integrity assessment is a major activity for all helicopter operators. The accurate estimation of component loads is an important element in life cycle management and life extension efforts. This paper explores continued efforts to utilize a wide variety of computational intelligence techniques to estimate some of these helicopter dynamic loads. Estimates for two main rotor sensors (main rotor normal bending and pushrod axial load) on the Australian Black Hawk helicopter were generated from an input set that consisted of thirty standard flight state and control system parameters. These estimates were produced for two flight conditions: full speed forward level flight and left rolling pullout at 1.5g. Two sampling schemes were attempted, specifically k-leaders sampling and a biased sampling scheme. Ensembles were constructed from the top performing models that used conjugate gradient, Levenberg-Marquardt (LM), extreme learning machines, and particle swarm optimization (PSO) as the learning method. Hybrid and memetic approaches combining the deterministic optimization and evolutionary computation techniques were also explored. The results of this work show that using a biased sampling scheme significantly improved the predictions, particularly at the peak values of the target signal. Hybrid models using PSO and LM learning provided accurate and correlated predictions for the main rotor loads in both flight conditions. DA - 2012/06/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 10db696b-8a8c-4547-b93c-48837b7cb311 ER - TY - JOUR TI - Use of evolutionary computation techniques for exploration and prediction of helicopter loads DO - 10.1109/CEC.2012.6252905 AU - Cheung, Catherine AU - Valdes, Julio J. AU - Li, Matthew T2 - IEEE 2012 World Congress on Computational Intelligence, IEEE 2012 Congress on Evolutionary Computation T3 - IEEE 2012 Congress on Evolutionary Computation CEC 2012, June 10-15, 2012, Brisbane, Australia SP - 1 EP - 8 AB - The development of accurate load spectra for helicopters is necessary for life cycle management and life extension efforts. This paper explores continued efforts to utilize evolutionary computation (EC) methods and machine learning techniques to estimate several helicopter dynamic loads. Estimates for the main rotor normal bending (MRNBX) on the Australian Black Hawk helicopter were generated from an input set that included thirty standard flight state and control system parameters under several flight conditions (full speed forward level flight, rolling left pullout at 1:5g, and steady 45◦ left turn at full speed). Multiobjective genetic algorithms (MOGA) used in combination with the Gamma test found reduced subsets of predictor variables with modeling potential. These subsets were used to estimate MRNBX using Cartesian genetic programming and neural network models trained by deterministic and evolutionary computation techniques, including particle swarm optimization (PSO), differential evolution (DE), and MOGA. PSO and DE were used alone or in combination with deterministic methods. Different error measures were explored including a fuzzy-based asymmetric error function. EC techniques played an important role in both the exploratory and modeling phase of the investigation. The results of this work show that the addition of EC techniques in the modeling stage generated more accurate and correlated models than could be obtained using only deterministic optimization. DA - 2012/06/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ce893984-d691-4e9c-9609-908b719ce15e ER - TY - JOUR TI - #Emotional Tweets AU - Mohammad, Saif M T2 - Proceedings of First Joint Conference on Lexical and Computational Semantics (*Sem) T3 - First Joint Conference on Lexical and Computational Semantics (*Sem), June 7-8, 2012, Montreal, Quebec, Canada SP - 246 EP - 255 AB - Detecting emotions in microblogs and social media posts has applications for industry, health, and security. However, there exists no microblog corpus with instances labeled for emotions for developing supervised systems. In this paper, we describe how we created such a corpus from Twitter posts using emotionword hashtags. We conduct experiments to show that the self-labeled hashtag annotations are consistent and match with the annotations of trained judges. We also show how the Twitter emotion corpus can be used to improve emotion classification accuracy in a different domain. Finally, we extract a word–emotion association lexicon from this Twitter corpus, and show that it leads to significantly better results than the manually crafted WordNet Affect lexicon in an emotion classification task. DA - 2012/06/01 PY - 2012 PB - Association for Computational Linguistics (ACL) LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 36edfec2-bcd9-427f-9812-201e6d192fbf ER - TY - JOUR TI - Expression, purification and analysis of an Arabidopsis recombinant CBL-interacting protein kinase3 (CIPK3) and its constitutively active form DO - 10.1016/j.pep.2012.08.013 AU - Gao, Peng AU - Kolenovsky, Allan AU - Cui, Yuhai AU - Cutler, Adrian J. AU - Tsang, Edward W. T. T2 - Protein Expression and Purification VL - 86 IS - 1 SP - 45 EP - 52 KW - CIPK3 KW - Site-directed mutagenesis KW - Inclusion bodies KW - Sarkosyl KW - Enzymatically active KW - Affinity purification KW - Protein kinase KW - Peptide phosphorylation AB - CIPK3 is a member of CBL (calcineurin B-like)-interacting serine–threonine protein kinases which play an important role in many developmental and adaptation processes in Arabidopsis. Studies conducted on members of this family such as SOS2, PKS8 and PKS11 have provided insight into how these kinases interact with their target substrates in the signal-response process. Since SOS2, PKS8 and PKS11 have low enzymatic activities in vitro and their amino acid sequences are homologous to that of CIPK3, it was assumed that CIPK3 would have a low enzymatic activity. To enhance CIPK3 enzyme activity, a constitutively active form, CIPK3T183D, was generated by a Thr¹⁸³ to Asp¹⁸³ substitution in the activation loop. To obtain proteins for analysis, glutathione S-transferase (GST) fusion protein system was used. Although both CIPK3 and CIPK3T183D were successfully expressed, they were found in inclusion bodies with three truncated proteins. Since the truncated proteins had a similar affinity to the GST-Bind Resin as the target protein, the one-step affinity purification could no longer be used. As an alternative, His fusion protein expression system was employed for protein production. Although both His-CIPK3 and His-CIPK3T183D also accumulated in inclusion bodies, they were expressed as a single protein species. A method involving Sarkosyl was developed for isolating and purifying the His fusion proteins. His-CIPK3 and HisCIPK3T183D produced were highly purified and enzymatically active. In addition, a 9-fold increase in kinase activity in His-CIPK3T183D was observed, indicating that Thr¹⁸³ to Asp¹⁸³ substitution in the activation loop of CIPK3 had succeeded in enhancing the kinase activity. DA - 2012/09/14 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6161c36c-6d07-4863-b113-33c53c9c92eb ER - TY - JOUR TI - Chemical inhibition of potato ABA8'-hydroxylase activity alters in vitro and in vivo ABA metabolism and endogenous ABA levels but does not affect potato microtuber dormancy duration DO - 10.1093/jxb/ers146 AU - Suttle, Jeffrey C. AU - Abrams, Suzanne R. AU - De Stefano-Beltran, Luis AU - Huckle, Linda L. T2 - Journal of Experimental Botany VL - 63 IS - 15 SP - 5717 EP - 5725 KW - ABA KW - ABA-8'-hydroxylase KW - abscisic acid KW - dormancy KW - microtuber KW - mixed-function oxidase KW - P450 KW - potato KW - Solanum tubersum L. AB - The effects of azole-type P450 inhibitors and two metabolism-resistant abscisic acid (ABA) analogues on in vitro ABA-8'-hydroxylase activity, in planta ABA metabolism, endogenous ABA content, and tuber meristem dormancy duration were examined in potato (Solanum tuberosum L. cv. Russet Burbank). When functionally expressed in yeast, three potato CYP707A genes were demonstrated to encode enzymatically active ABA-8'-hydroxylases with micromolar affinities for (+)-ABA. The in vitro activity of the three enzymes was inhibited by the P450 azole-type inhibitors ancymidol, paclobutrazol, diniconazole, and tetcyclasis, and by the 8'-acetylene- and 8'-methylene-ABA analogues, with diniconazole and tetcyclasis being the most potent inhibitors. The in planta metabolism of [3H](±)-ABA to phaseic acid and dihydrophaseic acid in tuber meristems was inhibited by diniconazole, tetcyclasis, and to a lesser extent by 8'-acetylene- and 8'-methylene-ABA. Continuous exposure of in vitro generated microtubers to diniconazole resulted in a 2-fold increase in endogenous ABA content and a decline in dihydrophaseic acid content after 9 weeks of development. Similar treatment with 8'-acetylene-ABA had no effects on the endogenous contents of ABA or phaseic acid but reduced the content of dihydrophaseic acid. Tuber meristem dormancy progression was determined ex vitro in control, diniconazole-, and 8'-acetylene-ABA-treated microtubers following harvest. Continuous exposure to diniconazole during microtuber development had no effects on subsequent sprouting at any time point. Continuous exposure to 8'-acetylene-ABA significantly increased the rate of microtuber sprouting. The results indicate that, although a decrease in ABA content is a hallmark of tuber dormancy progression, the decline in ABA levels is not a prerequisite for dormancy exit and the onset of tuber sprouting. DA - 2012/06/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 46599dd6-56aa-43ed-a5d2-7693bbf3d054 ER - TY - JOUR TI - Disaggregating categories of electrical energy end-use from whole-house hourly data DO - 10.1016/j.enbuild.2012.03.025 AU - Birt, Benjamin J. AU - Newsham, Guy R. AU - Beausoleil-Morrison, Ian AU - Armstrong, Marianne M. AU - Saldanha, Neil AU - Rowlands, Ian H. T2 - Energy and Buildings SN - 0378-7788 VL - 50 SP - 93 EP - 102 KW - load disaggregation; residential; electricity; smart meter; Canada AB - The residential sector uses nearly 30% of all electricity in Canada, and, it is important to know how this energy is being used, so that savings may be identified and realised. We propose a method that can be applied to hourly whole-house electrical energy data to partially disaggregate total household electricity use into five load categories/parameters (base load, activity load, heating season gradient, cooling season gradient and lowest external temperature at which air-conditioning is used). This paper develops the proposed method, and verifies it using high-resolution end-use data from twelve households with known characteristics. We then apply the method to hourly whole-house (smart meter) data from 327 households in Ontario. The roll-out of smart (advanced) metering infrastructure in many countries will make hourly whole-house data abundant, and we propose that this method could be widely applied by utilities to target their demand-side management programs towards households more likely to provide benefits, thus increasing the cost-effectiveness of such programs. DA - 2012/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4785b057-1a97-48fd-8f46-4607ef80f21e ER - TY - JOUR TI - Identity verification based on haptic handwritten signatures: genetic programming with unbalanced data DO - 10.1109/CISDA.2012.6291531 AU - Alsulaiman, Fawaz A. AU - Valdes, Julio J. AU - El Saddik, Alsulaiman T2 - (CISDA 2012): Proceedings of the IEEE Symposium on Computational Intelligence for Security and Defence Applications T3 - 2012 IEEE Symposium on Computational Intelligence for Security and Defence Applications (CISDA), July 11-13, 2012, Ottawa, Ontario, Canada SN - 978-1-4673-1416-9 SP - 1 EP - 7 KW - Haptics; Biometrics; Genetic Programming; user verification; classification AB - In this paper, haptic-based handwritten signature verification using Genetic Programming (GP) classification is presented. The relevance of different haptic data types (e.g., force, position, torque, and orientation) in user identity verification is investigated. In particular, several fitness functions are used and their comparative performance is investigated. They take into account the unbalance dataset problem (large disparities within the class distribution), which is present in identity verification scenarios. GP classifiers using such fitness functions compare favorably with classical methods. In addition, they lead to simple equations using a much smaller number of attributes. It was found that collectively, haptic features were approximately as equally important as visual features from the point of view of their contribution to the identity verification process. DA - 2012/07/13 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 796e046d-8a93-4645-902e-903f132c5dbd ER - TY - JOUR TI - Spotting keywords and sensing topic changes in speech DO - 10.1109/CISDA.2012.6291537 AU - Zhu, Xiaodan T2 - CISDA 2012: Proceedings of the IEEE Symposium on Computational Intelligence for Security and Defence Applications T3 - IEEE Symposium on Computational Intelligence for Security and Defence Applications (CISDA 2012), July 11-13, 2012, Ottawa, Ontario, Canada SN - 978-1-4673-1416-9 SP - 1 EP - 7 KW - keyword spotting; topic segmentation; speech understanding AB - Security concerns involved in dealing with sensitive information conveyed in human languages must be able to handle speech, which is the most basic, natural form of human communication and a huge amount of data are being generated daily. Dealing with such data is naturally associated with typical big-data problems in terms of both computational complexity and storage space. Unfortunately, compared with written texts, speech is inherently more difficult to browse, if no technical support is provided. In this paper we are interested in spotting keywords, which could reflect a security agent's information needs, and study its usefulness in helping automatically disclose topic changes (boundaries) in speech data under concern. Our results show that keyword spotting can help identify topics with a competitive performance. DA - 2012/07/13 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0c7d411a-efcb-4e7c-9674-02a22949eacb ER - TY - JOUR TI - Simulating social commerce applied to buyer group pricing, recommendation incentives, and bundling DO - 10.1145/2346536.2346554 AU - Spencer, Bruce AU - Buffett, Scott T2 - ICEC 2012: International Conference on Electronic Commerce T3 - 14th Annual International Conference on Electronic Commerce, August 7-8, 2012, Singapore SN - 978-1-4503-1197-7 SP - 95 EP - 98 AB - Currently social networks are used by buyers to become more aware of sellers and their goods. Increasingly, they are used with three other market mechanisms: Buyers use social networks to form buyer groups that leverage purchasing power. Sellers incentivize buyers to post recommendations on social media. Sellers or buyers compose compatible items into bundles with increased value and reduced price. In this paper we study the potential e ects of social networks on these mechanisms. For comprehensive and consistent coverage, we simulate combinations of these mechanisms, using published metrics for authenticity. Our results show seller pro tability increases with the use of social networks applied to all possible combinations. DA - 2012/08/08 PY - 2012 PB - Association for Computing Machinery LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 42efbf7d-dc49-496b-9c0d-0eeb5f225185 ER - TY - JOUR TI - Filtering and routing multilingual documents for translation DO - 10.1109/CISDA.2012.6291536 AU - Carpuat, Marine AU - Goutte, Cyril AU - Isabelle, Pierre T2 - 2012 IEEE Symposium on Computational Intelligence for Security and Defence Applications (CISDA 2012) T3 - 2012 IEEE Symposium on Computational Intelligence for Security and Defence Applications (CISDA), July 11-13, 2012, Ottawa, Ontario, Canada SN - 978-1-4673-1416-9 SP - 1 EP - 7 AB - Translation is a key capability to access relevant information expressed in various languages on social media. Unfortunately, systematically translating all content far exceeds the capacity of most organizations. Computer-aided translation (CAT) tools can significantly increase the productivity of translators, but can not ultimately cope with the overwhelming amount of content to translate. In this contribution, we describe and experiment with an approach where we use the structure in a corpus to adequately route the content to the proper workflow, including translators, CAT tools or purely automatic approaches. We show that linguistically motivated structure such as document genre can help decide on the proper translation workflow. However, automatically discovered structure has an effect that is at least as important and allows us to define groups of documents that may be translated automatically with reasonable output quality. This suggests that computational intelligence models that can efficiently organize document collection will provide increased capability to access textual content from various target languages. DA - 2012/07/13 PY - 2012 PB - IEEE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 12610fd4-0110-475e-bc5c-0dfc0481f7de ER - TY - JOUR TI - The trouble with SMT consistency AU - Carpuat, Marine AU - Simard, Michel T2 - Proceedings of the 7th Workshop on Statistical Machine Translation T3 - 7th Workshop on Statistical Machine Translation, June 7-8, 2012, Montreal, Quebec SP - 442 EP - 449 AB - SMT typically models translation at the sentence level, ignoring wider document context. Does this hurt the consistency of translated documents? Using a phrase-based SMT system in various data conditions, we show that SMT translates documents remarkably consistently, even without document knowledge. Nevertheless, translation inconsistencies often indicate translation errors. However, unlike in human translation, these errors are rarely due to terminology inconsistency. They are more often symptoms of deeper issues with SMT models instead. DA - 2012/06/08 PY - 2012 PB - Association for Computational Linguistics UR - http://www.aclweb.org/anthology-new/W/W12/W12-3156.pdf LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a7b9f071-84b0-48c8-a215-312739ffe880 ER - TY - JOUR TI - Liuwei Dihuang (LWDH), a traditional Chinese medicinal formula, protects against β-amyloid toxicity in transgenic caenorhabditis elegans DO - 10.1371/journal.pone.0043990 AU - Sangha, Jatinder S. AU - Sun, Xiaoli AU - Wally, Owen S. D. AU - Zhang, Kaibin AU - Ji, Xiuhong AU - Wang, Zhimin AU - Wang, Yanwen AU - Zidichouski, Jeffrey AU - Prithiviraj, Balakrishnan AU - Zhang, Junzeng T2 - PLos ONE VL - 7 IS - 8 KW - Liuwei Dihuang KW - LWDH KW - beta-amyloid AB - Liuwei Dihuang (LWDH), a classic Chinese medicinal formula, has been used to improve or restore declined functions related to aging and geriatric diseases, such as impaired mobility, vision, hearing, cognition and memory. Here, we report on the effect and possible mechanisms of LWDH mediated protection of b-amyloid (Ab) induced paralysis in Caenorhabditis elegans using ethanol extract (LWDH-EE) and water extract (LWDH-WE). Chemical profiling and quantitative analysis revealed the presence of different levels of bioactive components in these extracts. LWDH-WE was rich in polar components such as monosaccharide dimers and trimers, whereas LWDH-EE was enriched in terms of phenolic compounds such as gallic acid and paeonol. In vitro studies revealed higher DPPH radical scavenging activity for LWDH-EE as compared to that found for LWDH-WE. Neither LWDH-EE nor LWDH-WE were effective in inhibiting aggregation of Ab in vitro. By contrast, LWDH-EE effectively delayed Ab induced paralysis in the transgenic C. elegans (CL4176) model which expresses human Ab1–42. Western blot revealed no treatment induced reduction in Ab accumulation in CL4176 although a significant reduction was observed at an early stage with respect to b-amyloid deposition in C. elegans strain CL2006 which constitutively expresses human Ab1–42. In addition, LWDH-EE reduced in vivo reactive oxygen species (ROS) in C. elegans (CL4176) that correlated with increased survival of LWDH-EE treated N2 worms under juglone-induced oxidative stress. Analysis with GFP reporter strain TJ375 revealed increased expression of hsp16.2::GFP after thermal stress whereas a minute induction was observed for sod3::GFP. Quantitative gene expression analysis revealed that LWDH-EE repressed the expression of amy1 in CL4176 while up-regulating hsp16.2 induced by elevating temperature. Taken together, these results suggest that LWDH extracts, particularly LWDH-EE, alleviated b-amyloid induced toxicity, in part, through up-regulation of heat shock protein, antioxidant activity and reduced ROS in C. elegans. DA - 2012/08/30 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 875ccac7-7b26-4032-a2f6-9860b621cb35 ER - TY - JOUR TI - Are emissions of black carbon from gasoline vehicles underestimated? Insights from near and on-road measurements DO - 10.1021/es2033845 AU - Liggio, John AU - Gordon, Mark AU - Smallwood, Gregory AU - Li, Shao-Meng AU - Stroud, Craig AU - Staebler, Ralf AU - Lu, Gang AU - Lee, Patrick AU - Taylor, Brett AU - Brook, Jeffrey R. T2 - Environmental Science and Technology VL - 46 IS - 9 SP - 4819 EP - 4828 AB - Measurements of black carbon (BC) with a high-sensitivity laser-induced incandescence (HS-LII) instrument and a single particle soot photometer (SP2) were conducted upwind, downwind, and while driving on a highway dominated by gasoline vehicles. The results are used with concurrent CO2 measurements to derive fuel-based BC emission factors for real-world average fleet and heavy-duty diesel vehicles separately. The derived emission factors from both instruments are compared, and a low SP2 bias (relative to the HS-LII) is found to be caused by a BC mass mode diameter less than 75 nm, that is most prominent with the gasoline fleet but is not present in the heavy-duty diesel vehicle exhaust on the highway. Results from both the LII and the SP2 demonstrate that the BC emission factors from gasoline vehicles are at least a factor of 2 higher than previous North American measurements, and a factor of 9 higher than currently used emission inventories in Canada, derived with the MOBILE 6.2C model. Conversely, the measured BC emission factor for heavy-duty diesel vehicles is in reasonable agreement with previous measurements. The results suggest that greater attention must be paid to black carbon from gasoline engines to obtain a full understanding of the impact of black carbon on air quality and climate and to devise appropriate mitigation strategies. DA - 2012/02/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 820efae6-31dd-4cf9-9fff-8151aec77521 ER - TY - JOUR TI - Raman and infrared spectroscopy of α and β phases of thin nickel hydroxide films electrochemically formed on nickel DO - 10.1021/jp303546r AU - Hall, David Scott AU - Lockwood, David J AU - Poirier, Shawn AU - Bock, Christina AU - MacDougall, Barry R T2 - The Journal of Physical Chemistry A VL - 116 IS - 25 SP - 6771 EP - 6784 AB - The present work utilizes Raman and infrared (IR) spectroscopy, supported by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) to re-examine the fine structural details of Ni(OH)2, which is a key material in many energy-related applications. This work also unifies the large body of literature on the topic. Samples were prepared by the galvanostatic basification of nickel salts and by aging the deposits in hot KOH solutions. A simplified model is presented consisting of two fundamental phases (α and β) of Ni(OH)2 and a range of possible structural disorder arising from factors such as impurities, hydration, and crystal defects. For the first time, all of the lattice modes of β-Ni(OH)2 have been identified and assigned using factor group analysis. Ni(OH)2 films can be rapidly identified in pure and mixed samples using Raman or IR spectroscopy by measuring their strong O–H stretching modes, which act as fingerprints. Thus, this work establishes methods to measure the phase, or phases, and disorder at a Ni(OH)2 sample surface and to correlate desired chemical properties to their structural origins. DA - 2012/05/29 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b3b680ee-2127-4e26-a132-aca16a447a3c ER - TY - JOUR TI - Electrospun nanofiber membranes from polysulfones with chiral selector aimed for optical resolution DO - 10.1016/j.eurpolymj.2012.07.003 AU - Mizushima, Hiroaki AU - Yoshikawa, Masakazu AU - Li, Nanwen AU - Robertson, Gilles P. AU - Guiver, Michael D. T2 - European Polymer Journal SN - 0014-3057 VL - 48 IS - 10 SP - 1717 EP - 1725 KW - chiral separation KW - electrospray deposition KW - membrane KW - nanofiber fabric KW - optical resolution KW - permselectivity KW - polysulfone AB - Polysulfones with three types of alanyl residue, such as N-α-acetylalanine (Ac-Ala-OH), N-α-benzoylalanine (Bzo-Ala-OH), and N-α-benzyloxycarbonylalanine (Z-Ala-OH), as chiralselectors were prepared by polymer reaction. The resulting modified polysulfones showed chiroptical properties, indicating that the chiralselector residues were successfully introduced into the polysulfone. Nanofibermembranes prepared from the polymeric materials showed adsorption selectivity toward mixtures of racemic Glu, which were adopted as model racemates. Flux values for the nanofibermembranes were enhanced two to three orders of magnitude in comparison with the corresponding typical membranes, but without reduction in permselectivity. In the present study, it is shown that nanofiber is a suitable membrane form not only for molecularly imprinted membranes, but it exhibits enhanced throughput in comparison with typical dense membranes without concurrent reduction in permselectivity. DA - 2012/09/10 PY - 2012 PB - Elsevier PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a8215e0b-780d-40b5-b02c-01d032918a52 ER - TY - JOUR TI - Roles for endothelin receptor B and BCL2A1 in spontaneous CNS metastasis of melanoma DO - 10.1158/0008-5472.CAN-12-2194 AU - Cruz-Munoz, William AU - Jaramillo, Maria L. AU - Man, Shan AU - Xu, Ping AU - Banville, Myriam AU - Collins, Catherine AU - Nantel, Andre AU - Morgan, Sherif S. AU - Cranmer, Lee D. AU - O'Connor-McCourt, Maureen D. AU - Kerbel, Robert S. T2 - Cancer Research SP - 1 EP - 29 AB - Metastatic spread of melanoma to CNS is a common and devastating manifestation of disease progression, which, despite its clinical importance, remains poorly understood with respect to undelying molecular mechanisms. Using a recently developed preclinical model of spontaneous melanoma CNS metastasis, we have identified alterations in expression of endothelin receptor B (ednrb) as a potential factor that influences brain metastatic potential. Induced overexpression of this gene mediated enhanced overall metastatic disease, and resulted in an increased incidence of spontaneous CNS metastases. In contrast, the overexpression of other highlighted genes, such as bcl2a1, did not affect the incidence of CNS metastases but nevertheless appears to facilitate intracranial tumor growth. The pro-metastatic effect in the CNS associated with EDNRB appears to be mediated by the interaction with its ligands resulting in enhanced tumor cell proliferation and thus intracranial melanoma growth. That EDRNB contributes to melanoma metastasis is underscored by the fact that its therapeutic inhibition by the EDNRB-specific inhibitor, A192621, translated into improved outcomes when treating mice with either visceral metastases or intracranial tumors. The identification of an influential role of EDNRB in CNS melanoma spontaneous metastasis may provide both a target for therapeutic intervention as well as a potential prognostic marker for patients having an increased predisposition for incidence of CNS melanoma metastases. DA - 2012/08/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cfbc86eb-508d-4937-9fe1-26f3f9548fdd ER - TY - JOUR TI - Polymers of intrinsic microporosity (PIMs) substituted with methyl tetrazole DO - 10.1016/j.polymer.2012.07.055 AU - Du, Naiying AU - Robertson, Gilles P. AU - Dal-Cin, Mauro M. AU - Scoles, Ludmila AU - Guiver, Michael D. T2 - Polymer VL - 53 IS - 20 SP - 4367 EP - 4372 KW - Microporosity KW - Membrane KW - Tetrazole AB - A polymer of intrinsic microporosity (PIM-1) containing nitrile groups was reacted by [2 + 3] cycloaddition reaction to give a polymer substituted with tetrazole groups (TZ-PIM), and then was further methylated to give a new PIM substituted with methyl tetrazole groups (MTZ-PIM). In contrast to TZ-PIMs, the MTZ-PIMs had distinctly improved solubility characteristics, enabling a more detailed investigation of the degree of conversion for the cycloaddition reaction and the structures of TZ-PIMs, which showed the presence of two kinds of tetrazole rings. Compared with PIM-1, the MTZ-PIM showed higher gas permselectivity with a corresponding decrease in gas permeability for pure gas pairs such as O₂/N₂ and CO₂/N₂, and for mixed gases, such as CO₂/N₂. Data for selectivity coupled with high gas permeability is close to the Robeson 2008 upper-bound performance limit for the O₂/N₂ and CO2/N2 pure gas pairs, and exceeds the upper-bound for the CO₂/N₂ mixed gas pair. DA - 2012/07/31 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 584dbcc2-c1c3-43d6-a70b-ac4e93258ecf ER - TY - JOUR TI - Application of the Hough transform for the automatic determination of soot aggregate morphology DO - 10.1364/AO.51.000610 AU - Grishin, Igor AU - Thomson, Keven AU - Migliorini, Francesca AU - Sloan, James J. T2 - Applied Optics VL - 51 IS - 5 SP - 610 EP - 620 AB - We report a new method for automated identification and measurement of primary particles within soot aggregates as well as the sizes of the aggregates and discuss its application to high-resolution transmission electron microscope (TEM) images of the aggregates. The image processing algorithm is based on an optimized Hough transform, applied to the external border of the aggregate. This achieves a significant data reduction by decomposing the particle border into fragments, which are assumed to be spheres in the present application, consistent with the known morphology of soot aggregates. Unlike traditional techniques, which are ultimately reliant on manual (human) measurement of a small sample of primary particles from a subset of aggregates, this method gives a direct measurement of the sizes of the aggregates and the size distributions of the primary particles of which they are composed. The current version of the algorithm allows processing of high-resolution TEM images by a conventional laptop computer at a rate of 1–2 ms per aggregate. The results were validated by comparison with manual image processing, and excellent agreement was found. DA - 2012/02/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5cc4b7e4-7c05-4758-b40a-b2661ee416f1 ER - TY - JOUR TI - Metal supported tubular solid oxide fuel cells fabricated by suspension plasma spray and suspension high velocity oxy-fuel spray DO - 10.1016/j.jpowsour.2012.05.031 AU - Yoo, Yeong AU - Wang, Youliang AU - Deng, Xiaohua AU - Singh, Devinder AU - Legoux, Jean-Gabriel T2 - Journal of Power Sources VL - 215 SP - 307 EP - 311 KW - Metal supported KW - Tubular KW - Suspension plasma spray KW - Suspension HVOF spray KW - Low temperature solid oxide fuel cell AB - Low temperature (LT) metalsupportedsolidoxidefuelcells (SOFCs) have many advantages in comparison to conventional electrode or electrolyte supported type SOFCs. NRC has demonstrated high performance LT metalsupported planar SOFCs fabricated by either wet colloidal spray/sintering or suspension thermal spray. The combination of tubular configuration and metalsupported SOFCs may produce more unique and very attractive advantages such as easy and inexpensive sealing method and materials, high specific and volumetric power density, cost-effective fabrication, enhanced robustness, rapid start up, red-ox cycle tolerance and potential use for a pressurized integrated system. In this paper, thin film solid electrolyte of Sm₀.₂Ce₀.₈O₁.₉₀ (SDC) and NiO-SDC composite anode on sintered porous tubularmetal supports were deposited by suspension HVOF spray and suspensionplasmaspray, respectively on sintered porous tubularmetal support. La₀.₆Sr₀.₄Co₀.₂Fe₀.₈O₃₋δ (LSCF) cathode on the SDC electrolyte was formed by wet colloidal spray and subsequent sintering process as the final fabrication step. The detailed investigation of suspension and process-related parameters for suspension thermal spray was performed in order to produce thin and crack-free SDC thin film coatings. The electrochemical performance of single cells was demonstrated. DA - 2012/05/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 16c86e85-8738-4c21-bea5-721144c8a334 ER - TY - JOUR TI - Selective inhibition of USP7 DO - 10.1016/j.chembiol.2012.04.001 AU - Menard, Robert AU - Sulea, Traian T2 - Chemistry & Biology VL - 19 IS - 4 SP - 437 EP - 438 AB - The deubiquitinating enzyme USP7 is an emerging oncology and antiviral target. Reverdy et al., in this issue of Chemistry & Biology, disclose the first small-molecule inhibitor selective for USP7, which recapitulates its knockdown in cancer cells and hence demonstrates the therapeutic feasibility of USP7 inhibitors. DA - 2012/04/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4cd66c2d-8ff5-4c33-843d-3876f7ce0c8e ER - TY - JOUR TI - Lateral resolution challenges for triangulation-based three-dimensional imaging systems DO - 10.1117/1.OE.51.2.021111 AU - MacKinnon, David AU - Beraldin, Jean-Angelo AU - Cournoyer, Luc AU - Picard, Michel AU - Blais, Francois T2 - Optical Engineering VL - 51 IS - 2 KW - lateral resolution KW - modeling KW - system response KW - 3D imaging system KW - triangulation-based 3D imaging system KW - laser imaging system AB - Lateral spatial resolution is a particularly challenging concept to quantify in triangulation-based 3D imaging systems. In this paper, we present these challenges, then describe an artifact-based methodology for evaluating the lateral resolution of a triangulation-based 3D imaging system that uses laser spots or laser lines. In particular, the response of a 3D imaging system to a spatial discontinuity (step edge) has traditionally been modelled as a first-order linear system. We model the response of a triangulation-based laser imaging system to a spatial step edge from first principles and demonstrate that the response should be modelled as a non-linear system. This model is then used as a basis for evaluating the lateral (structural) resolution of a triangulation-based laser imaging system. DA - 2012/03/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : afabd23d-d287-46b2-a6cd-c5ffa4d30bee ER - TY - JOUR TI - Enlarging paraphrase collections through generalization and instantiation AU - Fujita, Atsushi AU - Isabelle, Pierre AU - Kuhn, Roland T2 - Proceedings of the Joint Conference on Empirical Methods on Natural Language Processing and Computational Natural Language Learning T3 - Joint Conference on Empirical Methods on Natural Language Processing and Computational Natural Language Learning (EMNLP-CONLL 2012), Jeju Island, Korea, July 12-14, 2012 SP - 631 EP - 642 AB - This paper presents a paraphrase acquisition method that uncovers and exploits generalities underlying paraphrases: paraphrase patterns are first induced and then used to collect novel instances. Unlike existing methods, ours uses both bilingual parallel and monolingual corpora. While the former are regarded as a source of high-quality seed paraphrases, the latter are searched for paraphrases that match patterns learned from the seed paraphrases. We show how one can use monolingual corpora, which are far more numerous and larger than bilingual corpora, to obtain paraphrases that rival in quality those derived directly from bilingual corpora. In our experiments, the number of paraphrase pairs obtained in this way from monolingual corpora was a large multiple of the number of seed paraphrases. Human evaluation through a paraphrase substitution test demonstrated that the newly acquired paraphrase pairs are of reasonable quality. Remaining noise can be further reduced by filtering seed paraphrases. DA - 2012/07 PY - 2012 UR - http://aclweb.org/anthology-new/D/D12/D12-1058.pdf LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c56f83ba-76e7-4660-8a6f-89f069ee2c44 ER - TY - JOUR TI - Domain and function: a dual-space model of semantic relations and compositions DO - 10.1613/jair.3640 AU - Turney, Peter D. T2 - Journal of Artificial Intelligence Research (JAIR) VL - 44 SP - 533 EP - 585 AB - Given appropriate representations of the semantic relations between carpenter and wood and between mason and stone (for example, vectors in a vector space model), a suitable algorithm should be able to recognize that these relations are highly similar (carpenter is to wood as mason is to stone; the relations are analogous). Likewise, with representations of dog, house, and kennel, an algorithm should be able to recognize that the semantic composition of dog and house, dog house, is highly similar to kennel (dog house and kennel are synonymous). It seems that these two tasks, recognizing relations and compositions, are closely connected. However, up to now, the best models for relations are significantly different from the best models for compositions. In this paper, we introduce a dual-space model that unifies these two tasks. This model matches the performance of the best previous models for relations and compositions. The dual-space model consists of a space for measuring domain similarity and a space for measuring function similarity. Carpenter and wood share the same domain, the domain of carpentry. Mason and stone share the same domain, the domain of masonry. Carpenter and mason share the same function, the function of artisans. Wood and stone share the same function, the function of materials. In the composition dog house, kennel has some domain overlap with both dog and house (the domains of pets and buildings). The function of kennel is similar to the function of house (the function of shelters). By combining domain and function similarities in various ways, we can model relations, compositions, and other aspects of semantics. DA - 2012/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 516de82e-1166-4277-a137-ce267a5b21a9 ER - TY - JOUR TI - White versus gray matter : fMRI hemodynamic responses show similar characteristics, but differ in peak amplitude DO - 10.1186/1471-2202-13-91 AU - Fraser, Leanne M. AU - Stevens, M. Tynan AU - Beyea, Steven D. AU - D'Arcy, Ryan C. N. T2 - BMC Neuroscience VL - 13 IS - 1 SP - 91 KW - white matter KW - functional connectivity KW - BOLD response KW - hemodynamic response function KW - event-related AB - BACKGROUND: There is growing evidence for the idea of fMRI activation in white matter. In the current study, we compared hemodynamic response functions (HRF) in white matter and gray matter using 4 T fMRI. White matter fMRI activation was elicited in the isthmus of the corpus callosum at both the group and individual levels (using an established interhemispheric transfer task). Callosal HRFs were compared to HRFs from cingulate and parietal activation. RESULTS: Examination of the raw HRF revealed similar overall response characteristics. Finite impulse response modeling confirmed that the WM HRF characteristics were comparable to those of the GM HRF, but had significantly decreased peak response amplitudes. CONCLUSIONS: Overall, the results matched a priori expectations of smaller HRF responses in white matter due to the relative drop in cerebral blood flow (CBF) and cerebral blood volume (CBV). Importantly, the findings demonstrate that despite lower CBF and CBV, white matter fMRI activation remained within detectable ranges at 4 T. DA - 2012/08/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3dcf8692-cb2d-42d4-b660-09428a989f41 ER - TY - JOUR TI - Searching for poor quality machine translated text : learning the difference between human writing and machine translations DO - 10.1007/978-3-642-30353-1 AU - Carter, Dave AU - Inkpen, Diana T2 - Advances in Artificial Intelligence T2 - Lecture Notes in Artificial Intelligence (LNAI); 7310 T3 - 25th Canadian Conference on Artificial Intelligence, Canadian AI 2012, 28-30 May 2012, Toronto, Ontario, Canada SN - 0302-9743 SN - 978-3-642-30352-4 SP - 49 EP - 60 AB - As machine translation (MT) tools have become mainstream, machine translated text has increasingly appeared on multilingual websites. Trustworthy multilingual websites are used as training corpora for statistical machine translation tools; large amounts of MT text in training data may make such products less effective. We performed three experiments to determine whether a support vector machine (SVM) could distinguish machine translated text from human written text (both original text and human translations). Machine translated versions of the Canadian Hansard were detected with an F-measure of 0.999. Machine translated versions of six Government of Canada web sites were detected with an F-measure of 0.98.We validated these results with a decision tree classifier. An experiment to find MT text on Government of Ontario web sites using Government of Canada training data was unfruitful, with a high rate of false positives. Machine translated text appears to be learnable and detectable when using a similar training corpus. DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cf9f7d1a-96a1-4b36-8355-6c808a7f3f4d ER - TY - JOUR TI - Machine learning for resource management in smart environments DO - 10.1109/DEST.2012.6227910 AU - Fabbricatore, Christian AU - Boley, Harold AU - Karduck, Achim P. T2 - 2012 6th IEEE International Conference on Digital Ecosystem Technologies (DEST) T3 - 6th IEEE International Conference on Digital Ecosystem Technologies, 18-20 June 2012, Campione d’Italia, Italy KW - machine learning KW - resource management KW - energy savings KW - ambient assisted living KW - smart environment KW - semantic web AB - Efficient resource and energy management is a key research and business area in todays IT markets. Cyber-physical ecosystems, like smart homes (SHs) and smart Environments (SEs) get interconnected, the efficient allocation of resources will become essential. Machine Learning and Semantic Web techniques for improving resource allocation and management are the focus of our research. They allow machines to process information on all levels, inferring expressive knowledge from raw data, in particular resource predictions from usage patterns. Our aim is to devise a novel approach for a machine learning (ML) and resource Management (RM) framework in SEs. It combines ML and SemanticWeb techniques and integrates user interaction. The main objective is to enable the creation of platforms that decrease the overall resource consumption by learning and predicting various usage patterns, and furthermore making decisions based on user-feedback. For this purpose, we evaluate recent research and applications, elicit framework requirements, and present a framework architecture. The approach and components are assessed and a prototype implementation is described. DA - 2012/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 36c5d9b5-3e99-476d-abdc-c2edcf52c132 ER - TY - JOUR TI - Posture-invariant statistical shape analysis using Laplace operator DO - 10.1016/j.cag.2012.03.026 AU - Wuhrer, Stefanie AU - Shu, Chang AU - Xi, Pengcheng T2 - Computers & Graphics VL - 36 IS - 5 SP - 410 EP - 416 KW - statistical shape analysis KW - posture-invariant shape processing KW - Laplace operator AB - Statistical shape analysis is a tool that allows to quantify the shape variability of a population of shapes. Traditional tools to perform statistical shape analysis compute variations that reflect both shape and posture changes simultaneously. In many applications, such as ergonomic design applications, we are only interested in shape variations. With traditional tools, it is not straightforward to separate shape and posture variations. To overcome this problem, we propose an approach to perform statistical shape analysis in a posture-invariant way. The approach is based on a local representation that is obtained using the Laplace operator. DA - 2012/04/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 31788dea-617e-47fc-9b87-be11ddd94c55 ER - TY - JOUR TI - SemEval-2012 Task 2 : measuring degrees of relational similarity AU - Jurgens, David A. AU - Mohammad, Saif M. AU - Turney, Peter D. AU - Holyoak, Keith J. T2 - The First Joint Conference on Lexical and Computational Semantics. Volume 2: Proceedings of the 6th International Workshop on Semantic Evaluation (SemEval 2012), pages 356–364 T3 - SEM 2012 : The First Joint Conference on Lexical and Computational Semantics, 7-8 June 2012, Montreal, Quebec, Canada AB - Up to now, work on semantic relations has focused on relation classification: recognizing whether a given instance (a word pair such as virus:flu) belongs to a specific relation class (such as CAUSE:EFFECT). However, instances of a single relation class may still have significant variability in how characteristic they are of that class. We present a new SemEval task based on identifying the degree of prototypicality for instances within a given class. As a part of the task, we have assembled the first dataset of graded relational similarity ratings across 79 relation categories. Three teams submitted six systems, which were evaluated using two methods. DA - 2012/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6015b1d4-305a-43ea-b27e-ca2a5b073793 ER - TY - JOUR TI - WSReasoner : a prototype hybrid reasoner for ALCHOI ontology classification using a weakening and strengthening approach AU - Song, Weihong AU - Spencer, Bruce AU - Du, Weichang T2 - Proceedings of the 1st International Workshop on OWL Reasoner Evaluation Workshop (ORE 2012) in conjunction with 6th International Joint Conference on Automated Reasoning (IJCAR 2012) T3 - 6th International Joint Conference on Automated Reasoning (IJCAR 2012), Manchester, UK, June 26 - July 1, 2012 SN - 1613-0073 VL - 858 AB - In the ontology classification task, consequence-based reasoners are typically significantly faster while tableau-based reasoners can process more expressive DL languages. However, both of them have difficulty to classify some available large and complex ALCHOI ontologies with complete results in acceptable time. We present a prototype hybrid reasoning system WSReasoner, which is built upon and takes advantages of both types of reasoners to provide efficient classification service. In our proposed approach, we approximate the target ontology O by a weakened version Owk and a strengthened version Ostr , both are in a less expressive DL ALCH and classified by a consequence-based main reasoner. Classification of Owk produces a subset of subsumptions of ontology O and the target of the classification of Ostr is to produce a superset of subsumptions of O. Additional subsumptions derived from Ostr may be unsound, so they are further verified by a tableau-based assistant reasoner. For the ALCHOI ontologies in our experiment, except for one for which WSReasoner has not obtained the result, the number of subsumptions derived from WSReasoner is no fewer than from the reasoners that could finish the classification. Moreover, WSReasoner takes less time than tableau-based reasoners when the ALCHOI ontologies are large. DA - 2012/06/25 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2a0b97fc-a741-4519-976a-b2cf31c99fb7 ER - TY - JOUR TI - Mixing multiple translation models in statistical machine translation AU - Razmara, Majid AU - Foster, George AU - Sankaran, Baskaran AU - Sarkar, Anoop T2 - Proceedings of the 50th Annual Meeting of the Association for Computational Linguistics T3 - 50th Annual Meeting of the Association for Computational Linguistics (ACL 2012), Jeju Island, Republic of Korea, 8-14 July, 2012 AB - Statistical machine translation is often faced with the problem of combining training data from many diverse sources into a single translation model which then has to translate sentences in a new domain. We propose a novel approach, ensemble decoding, which combines a number of translation systems dynamically at the decoding step. In this paper, we evaluate performance on a domain adaptation setting where we translate sentences from the medical domain. Our experimental results show that ensemble decoding outperforms various strong baselines including mixture models, the current state-of-the-art for domain adaptation in machine translation. DA - 2012/07 PY - 2012 PB - Association for Computational Linguistics LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3a79c192-af06-4ff4-84a8-fbc03003c772 ER - TY - CHAP TI - Transductive relational classification in the co-training paradigm DO - 10.1007/978-3-642-31537-4_2 AU - Ceci, Michelangelo AU - Appice, Annalisa AU - Viktor, Herna L. AU - Malerba, Donato AU - Paquet, Eric AU - Guo, Hongyu T2 - Machine Learning and Data Mining in Pattern Recognition : 8th International Conference, MLDM 2012, Berlin, Germany, July 13-20, 2012. Proceedings T2 - Lecture Notes In Computer Science; 7376 T3 - 8th International Conference on Machine Learning and Data Mining (MLDM) 2012, July 13-20, 2012 Berlin, Germany SN - 0302-9743 SN - 978-3-642-31536-7 SN - 978-3-642-31537-4 SP - 11 EP - 25 KW - transductive learning KW - co-training KW - multi-relational classification AB - Consider a multi-relational database, to be used for classification, that contains a large number of unlabeled data. It follows that the cost of labeling such data is prohibitive. Transductive learning, which learns from labeled as well as from unlabeled data already known at learning time, is highly suited to address this scenario. In this paper, we construct multi-views from a relational database, by considering different subsets of the tables as contained in a multi-relational database. These views are used to boost the classification of examples in a co-training schema. The automatically generated views allow us to overcome the independence problem that negatively affect the performance of co-training methods. Our experimental evaluation empirically shows that co-training is beneficial in the transductive learning setting when mining multi-relational data and that our approach works well with only a small amount of labeled data. DA - 2012/07 PY - 2012 PB - Springer Berlin Heidelberg LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 31180664-b569-4563-b2d9-d685d276240a ER - TY - JOUR TI - Androgenesis-inducing stress treatments change phytohormone levels in anthers of three legume species (Fabaceae) DO - 10.1007/s00299-012-1246-8 AU - Lulsdorf, Monika AU - Yuan, Hai Ying AU - Slater, Susan AU - Vandenberg, Albert AU - Han, Xiumei AU - Zaharia, L. Irina T2 - Plant Cell Reports VL - 31 IS - 7 SP - 1255 EP - 1267 KW - Abscisic acid KW - auxin, cytokinin KW - gibberellin KW - centrifugation KW - electroporation KW - sonication KW - osmotic shock AB - Legumes are recalcitrant to androgenesis and induction protocols were only recently developed for pea (Pisum sativum L.) and chickpea (Cicer arietinum L.), albeit with low regeneration frequencies. Androgenesis is thought to be mediated through abscisic acid (ABA) but other phytohormones, such as auxins, cytokinins, and gibberellins, have also been implicated. In view of improving induction protocols, the hormone content of pea, chickpea, and lentil anthers was measured after exposure to cold, centrifugation, electroporation, sonication, osmotic shock, or various combinations thereof using an analytical mass spectrometer. Indole-3-acetic acid (IAA) had a key function during the induction process. In pea, high concentrations of IAA-asparagine (IAA-Asp), a putative IAA metabolite, accumulated during the application of the different stresses. In chickpea, the IAA-Asp concentration increased 30-fold compared to pea but only during the osmotic shock treatment and likely as a result of the presence of exogenous IAA in the medium. In contrast, no treatment in lentil (Lens culinaris) invoked such an increase in IAA-Asp content. Of the various cytokinins monitored, only cis zeatin riboside increased after centrifugation and electroporation in pea and possibly chickpea. No bioactive gibberellins were detected in any species investigated, indicating that this hormone group is likely not linked to androgenesis in legumes. In contrast to the other stresses, osmotic shock treatment caused a reduction in the levels of all hormones analyzed, with the exception of IAA-Asp in chickpea. A short period of low hormone content might be a necessary transition phase for androgenesis induction of legumes. DA - 2012/03/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c310e70e-2878-4221-8069-bb51d35f5fdd ER - TY - JOUR TI - Properties of polysaccharides in several seaweeds from Atlantic Canada and their potential anti-influenza viral activities DO - 10.1007/s11802-012-1906-x AU - Jiao, Guangling AU - Yu, Guangli AU - Wang, Wei AU - Xhao, Xiaoliang AU - Zhang, Junzeng AU - Ewart, Stephen H. T2 - Journal of Ocean University of China VL - 11 IS - 2 SP - 205 EP - 212 KW - anti-influenza viral activity KW - H1N1 KW - monosaccharide composition KW - polysaccharides AB - To explore the polysaccharides from selected seaweeds of Atlantic Canada and to evaluate their potential anti-influenza virus activities, polysaccharides were isolated from several Atlantic Canadian seaweeds, including three red algae (Polysiphonia lanosa, Furcellaria lumbricalis, and Palmaria palmata), two brown algae (Ascophyllum nodosum and Fucus vesiculosus), and one green alga (Ulva lactuca) by sequential extraction with cold water, hot water, and alkali solutions. These polysaccharides were analyzed for monosaccharide composition and other general chemical properties, and they were evaluated for anti-influenza virus activities. Total sugar contents in these polysaccharides ranged from 15.4% (in U. lactuca) to 91.4% (in F. lumbricalis); sulfation level was as high as 17.6% in a polysaccharide from U. lactuca, whereas it could not be detected in an alikali-extract from P. palmaria. For polysaccharides from red seaweeds, the main sugar units were sulfated galactans (agar or carrageenan) for P. lanosa, F. lumbricalis, and xylans for P. palmata. In brown seaweeds, the polysaccharides largely contained sulfated fucans, whereas the polysaccharides in green seaweed were mainly composed of heteroglycuronans. Screening for antiviral activity against influenza A/PR/8/34 (H1N1) virus revealed that brown algal polysaccharides were particularly effective. Seaweeds from Atlantic Canada are a good source of marine polysaccharides with potential antiviral properties. DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a62a5f06-fc50-4a0b-9893-299794fbbefe ER - TY - JOUR TI - Biodegradation of RDX nitroso products MNX and TNX by cytochrome P450 XpIA DO - 10.1021/es3011964 AU - Halasz, Annamaria AU - Manno, Dominic AU - Perreault, Nancy N. AU - Sabbadin, Federico AU - Bruce, Neil C. AU - Al-Hawari, Jalal T2 - Environmental Science & Technology VL - 46 IS - 13 SP - 7245 EP - 7251 AB - Anaerobic transformation of the explosive RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) by microorganisms involves sequential reduction of N-NO2 to the corresponding N-NO groups resulting in the initial formation of MNX (hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine). MNX is further reduced to the dinitroso (DNX) and trinitroso (TNX) derivatives. In this paper, we describe the degradation of MNX and TNX by the unusual cytochrome P450 XplA that mediates metabolism of RDX in Rhodococcus rhodochrous strain 11Y. XplA is known to degrade RDX under aerobic and anaerobic conditions, and, in the present study, was found able to degrade MNX to give similar products distribution including NO2-, NO3-, N2O, and HCHO but with varying stoichiometric ratio, that is, 2.06, 0.33, 0.33, 1.18, and 1.52, 0.15, 1.04, 2.06, respectively. In addition, the ring cleavage product 4-nitro-2,4,-diazabutanal (NDAB) and a trace amount of another intermediate with a [M-H]- at 102 Da, identified as ONNHCH2NHCHO (NO-NDAB), were detected mostly under aerobic conditions. Interestingly, degradation of TNX was observed only under anaerobic conditions in the presence of RDX and/or MNX. When we incubated RDX and its nitroso derivatives with XplA, we found that successive replacement of N-NO2 by N-NO slowed the removal rate of the chemicals with degradation rates in the order RDX > MNX > DNX, suggesting that denitration was mainly responsible for initiating cyclic nitroamines degradation by XplA. This study revealed that XplA preferentially cleaved the N-NO2 over the N-NO linkages, but could nevertheless degrade all three nitroso derivatives, demonstrating the potential for complete RDX removal in explosives-contaminated sites. DA - 2012/06/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b128ea00-7bf3-44ba-a1d9-96d16f8b2c81 ER - TY - JOUR TI - Comparison of four models to rank failure likelihood of individual pipes DO - 10.2166/hydro.2011.029 AU - Kleiner, Y. AU - Rajani, B. B. T2 - Journal of Hydroinformatics VL - 14 IS - 3 SP - 659?681 KW - Pipes and pipelines KW - Conduites AB - This paper describes alternative models developed into operational tools that can assist network owners and planners to identify individual mains for renewal in their water distribution networks. Four models were developed and compared: a heuristic model, naïve Bayesian classification model, a model based on logistic regression and finally a probabilistic model based on the Non Homogeneous Poisson Process (NHPP). These models rank individual water mains in terms of their anticipated breakage frequency, while considering both static (e.g., pipe material, diameter, vintage, surrounding soil, etc.) and dynamic (e.g., climate, operations, cathodic protection, etc.) effects influencing pipe deterioration rates. DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cea030fd-fba6-49a3-9b88-017dd7e0c3f2 ER - TY - JOUR TI - Some effects on natural ventilation system for subway tunnel fires AU - Kashef, A. AU - Yuan, Z. AU - Lei, B. T3 - Fifth International Symposium on Tunnel Safety & Security. Proceedings: 14 March 2012, New York, N.Y. USA SP - 1 EP - 9 KW - Tunnels, fires, emergency ventilation, fire and smoke control and visibility KW - Tunnels KW - Tunnels AB - A series of experiments, using a 1:15 model tunnel, were designed in accordance with the Froude conservation approach to investigate the influential parameters on temperature distributions in tunnel fires with natural ventilation. The effect of parameters such as fire size, shaft length and height were investigated. A natural ventilation system was achieved by introducing four vertical shafts spaced at 4 m in the ceiling of the tunnel. In the study reported in this paper, propane gas, located on the floor of the tunnel, was used to simulate the fire source which produced heat release rates in the range of 3.61kW to 12.2 kW. The smoke temperature distributions along the tunnel ceiling and in the vertical direction along the tunnel length were measured using K-type thermocouples trees. Based on the fire plume theory, a dimensionless temperature was defined and it was found that the fire size did not have a major effect on the dimensionless temperature. Despite the fact that the shaft sizes did not significantly affect the distribution of the temperature in the near-field of the fire, they did influence the temperature values with the temperatures dropping with the increase of shaft size. Based on the one-dimensional theory and rational assumptions, two formulas were developed to predict the ceiling longitudinal temperature distribution in tunnel fires with natural ventilation. AB - On a conçu une série d?expériences, en utilisant une maquette de tunnel à l?échelle 1:15, en conformité avec l?approche de conservation basée sur le nombre de Froude, pour étudier les paramètres influents sur les valeurs de répartition de la température dans des incendies en tunnel avec aération naturelle. On s?est penché sur l?incidence de paramètres tels que l?ampleur du foyer, ainsi que la longueur et la hauteur internes du tunnel. Un système d?aération naturelle a été mis en ?uvre par l?introduction dans le plafond du tunnel de quatre (4) puits verticaux espacés les uns des autres de 4 m. Dans le cadre de l?étude dont fait état notre document, du gaz propane a été utilisé sur le sol du tunnel pour simuler la source de l?incendie, laquelle produisait des dégagements de chaleur de l?ordre de 3,61 kW à 12,2 kW. Les valeurs de répartition des températures de la fumée le long du plafond du tunnel et dans la direction verticale sur sa longueur ont été mesurées au moyen d?arbres de thermocouples de type K. Sur la base de la théorie relative aux panaches de flammes, une température adimensionnelle a été définie, et l?on a découvert que l?ampleur du foyer n?influait pas de façon appréciable sur la température adimensionnelle. Bien que les dimensions du puits ne jouaient pas de façon significative sur la répartition de la température dans le champ proche de l?incendie, elles influençaient tout de même les valeurs de température, celles-ci étant d?autant plus basses que le puits était de grande dimension. Selon la théorie unidimensionnelle et les hypothèses rationnelles, deux (2) formules ont été développées pour prédire la répartition longitudinale au plafond des valeurs de température dans les incendies en tunnel avec aération naturelle. DA - 2012/03/14 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1d5f7a9c-7b99-444d-a2a6-02140f9625a2 ER - TY - JOUR TI - Effect of structural changes on acoustic performance of wood frame walls AU - Schoenwald, Stefan AU - Wenzke, Erik AU - King, Frances AU - Zeitler, Berndt T2 - Proceedings - European Conference on Noise Control T2 - EuroNoise T3 - EURONOISE: 10 June 2012, Prague, Czech Republic SN - 2226-5147 SN - 9788001050132 SP - 208 EP - 213 KW - Office acoustics KW - Acoustique des bureaux AB - Sometimes in wood frame construction wall assemblies are required that have a higher axial loadbearing capacity than conventional loadbearing wall designs. To increase the axial load bearingcapacity to carry higher vertical loads, i.e. dead load or traffic load of upper building storeys, theframing has to be stronger, which can be achieved by either decreasing the spacing of the studs orby using stronger studs at a wider spacing. These significant structural measures increase the wallstiffness and thus can also affect the airborne sound insulation of the wall assemblies. The effectof wall stiffness on airborne sound insulation was investigated, by analysing bendingwavenumbers measured along the primary axis on the gypsum board leaf of a common staggeredstud wood frame wall and of assemblies with smaller than typical stud spacing (i.e. <400 mm),with multi-stud columns at a wider spacing, and with shear membranes in various configurations.A correlation in the change of bending wavenumber results and the change of airborne soundinsulation was found in frequency ranges where the wall stiffness was influenced by the designchanges. The results are promising and a first step towards a method for the estimation ofairborne sound insulation changes from the mechanical properties of the wall. DA - 2012/09/13 PY - 2012 PB - European Acoustic Association LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5341210b-4cc2-4760-a954-25a733c65108 ER - TY - JOUR TI - Fire protection performance of Novec1230 in electronic facilities AU - Kim, A. K. T2 - Fire and Safety IS - Spring SP - 58 EP - 63 KW - Fire KW - Incendie KW - Suppression KW - Extinction DA - 2012/04/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3a02bbc8-f2f6-439e-88eb-8775c687d0fd ER - TY - JOUR TI - Household materials as emission sources of naphthalene in Canadian homes and their contribution to indoor air DO - 10.1016/j.atmosenv.2011.12.060 AU - Kang, Dong Hwa AU - Choi, Dong Hee AU - Won, Doyun AU - Yang, Wenping AU - Schleibinger, Hans AU - David, Jacinthe T2 - Atmospheric Environment VL - 50 SP - 79 EP - 87 KW - Naphthalene KW - household materials KW - emission source KW - Canadian homes KW - exposure KW - micro-scale chamber KW - Indoor air KW - Air intérieur AB - The objective of this study was to identify household materials that may contribute to the indoor naphthalene concentration in Canadian homes. Ninety-nine household materials including building materials, furnishings, and consumer products were tested. These materials included well-known naphthalene-containing products such as mothballs as well as building and consumer products where naphthalene could have been either added as part of a liquid formulation or used as a chemical intermediate in the manufacture of solid materials and product components. A fast screening method was used to determine the naphthalene concentration in a micro-scale test chamber. The tested materials were ranked based on the naphthalene emission strength combined with the amount of products typically used in homes. As expected, the results showed that mothballs, which had the highest emission factor, are one of the predominant sources. Interestingly, vinyl and wooden furniture with high emission factors and painted walls and ceiling with large surface areas were found to be important sources with the source strength even larger than those of mothballs when maximum emission factors were assumed for these building materials and furnishings. This suggests that some building materials and furnishings could be significant contributors to indoor naphthalene concentrations. This study shows that selecting materials with lower naphthalene emission factors could be one of many ways to reduce the indoor naphthalene concentration. AB - Cette étude avait pour objectif d?identifier les matériaux ménagers qui sont susceptibles de contribuer à la concentration de naphtalène à l?intérieur des maisons canadiennes. On a mis à l?essai à cette fin 99 matériaux ménagers, y compris des matériaux de construction, des meubles et des produits de consommation. Ces matériaux comprenaient des produits contenant du naphtalène qui sont bien connus comme les boules de naphtalène (boules-à-mites) ainsi que des produits de construction et de consommation dans lesquels on a pu soit ajouter le naphtalène comme partie d?une formulation liquide, soit l?employer comme intermédiaire réactionnel dans la fabrication de matériaux solides et de composants de produit. Une méthode de dépistage rapide a été employée pour déterminer la concentration de naphtalène dans une enceinte d?essai à échelle microscopique. Les matériaux mis à l?essai ont été classés suivant les teneurs en naphtalène combinées à la quantité de produits ordinairement employée dans les maisons. Comme prévu, les résultats indiquent que les boules de naphtalène, lesquelles possédaient le coefficient d?émission le plus élevé, représentent l?une des sources prédominantes. Il nous est apparu d?un intérêt particulier que les ameublements de vinyle et de bois possédant des coefficients d?émission élevés, et les murs et les plafonds peints ayant de grandes superficies, se sont révélés être des participants importants présentant des valeurs à la source encore plus élevées que celles des boules de naphtalène lorsque des coefficients d?émission maximum étaient considérés pour ces matériaux et ces types d?ameublement. Cette constatation indique que certains matériaux et types d?ameublement pourraient contribuer de façon significative aux concentrations de naphtalène à l?intérieur des bâtiments résidentiels. DA - 2012/04/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7eccc3e0-e0ca-4720-ae69-56614d4caccd ER - TY - JOUR TI - State of the art review of technologies for pipe structural health monitoring DO - 10.1109/JSEN.2011.2181161 AU - Liu, Z. AU - Kleiner, Y. T2 - IEEE Sensors Journal VL - 12 IS - 6 SP - 1987 EP - 1992 KW - pipe condition assessment, sensor, structural health monitoring, sensor data fusion KW - Pipes and pipelines KW - Conduites AB - This paper presents a state of the review of sensor technologies used for monitoring indicators pointing to pipe structural deterioration. The potential for multi-sensor system and sensor data fusion for condition-based maintenance are also discussed. DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 391b5d78-8f9f-4e23-8bd2-398ef1995d01 ER - TY - JOUR TI - Improved laser scan for pitting corrosion measurement by using super resolution technique DO - 10.1016/j.autcon.2011.06.002 AU - Liu, Z. AU - Krys, D. T2 - Automation in Construction VL - 21 SP - 172 EP - 183 KW - Ductile iron pipe, performance assessment, pitting corrosion, image super resolution, Markov random field KW - Pipes and pipelines KW - Conduites AB - In this paper, a single-frame super resolution method is proposed to infer a high-resolution laser scan from the low-resolution input. The relation between the low resolution input and high-resolution result is modeled with a Markov random field (MRF) with the aid of a training set built in advance. A belief propagation algorithm is implemented to infer the super-resolved result. The experiments demonstrate a good performance of the proposed method in comparison with the traditional interpolation methods. AB - Dans ce document, une méthode de super-résolution image par image est proposée pour inférer un balayage laser haute résolution à partir d?une entrée basse résolution. La relation entre l?entrée basse résolution et le résultat haute résolution est modélisée avec un champ MRF, à l?aide d?une base d?apprentissage construite au préalable. Un algorithme de propagation des croyances est mis en ?uvre pou inférer le résultat super-résolu. Ces expériences démontrent la performance satisfaisante de la méthode proposée par rapport aux méthodes d?interpolation classiques. DA - 2012/01/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 23d87f5d-5b2c-4713-a597-512b2bb010ba ER - TY - JOUR TI - Condensation risk assessment on box windows : the effect of the window-wall interface DO - 10.1177/1744259111411653 AU - Maref, W. AU - Van Den Bossche, N. AU - Armstrong, M. AU - Lacasse, M. A. AU - Elmahdy, H. AU - Glazer, R. T2 - Journal of Building Physics VL - 36 IS - 1 SP - 35 EP - 56 KW - condensation KW - window-wall interface KW - box window KW - pressure difference KW - deficiency KW - temperature index KW - laboratory experiment KW - guarded hot box KW - full-scale KW - Wall/Window interface KW - l'Interface fenêtre-mur AB - Windows generally have the lowest temperature index in current building types, and will consequently be the primary location for interior surface condensation. Surface temperatures can easily be calculated using thermal finite-element-models, but these generally omit the effect of convection in the windows and the window-wall interface. Hence, there is a need to determine if specific interface details provide potential for condensation on the window components in which air leakage paths may be prominent. The paper reports on a laboratory evaluation of condensation risk assessment in a hotbox, with varying pressure differences and the introduction of deficiencies. It was concluded that the effect of the type of insulation in the window-wall interface was very low for isobaric boundary conditions, whereas it has a significant effect when pressure differences are applied. AB - Ce sont généralement les fenêtres qui possèdent l?indice de température le plus bas dans les types de bâtiments actuels, et, en conséquence, elles constituent le principal emplacement favorisant la condensation sur les surfaces intérieures. Il est facile de calculer les températures superficielles au moyen de la modélisation par éléments finis, mais ces modèles omettent en généra l?incidence de la convection dans les fenêtres et l?interface fenêtre-mur. De là le besoin de déterminer si des détails d?interface précis offrent un potentiel de condensation sur les composants de fenêtre dans lesquels des trajectoires de fuite d?air peuvent être évidentes. Ce document fait état d?une étude menée en laboratoire sur l?évaluation du risque de condensation dans une boîte pour essais thermiques, faisant intervenir diverses valeurs de différences de pression et introduisant divers manques. On en conclut que l?incidence du type d?isolant dans l?interface fenêtre-mur était très faible pour les conditions limites isobares, tandis qu?elle était appréciable lorsque des différences de pression étaient appliquées. DA - 2012/06/28 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0e9044e4-48ca-4a69-a0f3-508dbcdcca4f ER - TY - JOUR TI - Comparison of proposed methods to include lightweight framed structures in EN 12354 prediction model AU - Schoenwald, Stefan T2 - Proceedings - European Conference on Noise Control T2 - Euronoise T3 - EURONOISE: 10 June 2012, Prague, Czech Republic SN - 2226-5147 SN - 9788001050132 SP - 174 EP - 179 KW - Building acoustics, flanking sound transmission, precition method KW - Office acoustics KW - Acoustique des bureaux AB - In this paper proposed methods are compared through prediction of flanking sound transmission across a wood frame wall-wall junction. Data measured in the NRC-IRC flanking sound transmission facility is used as input data as well as for the validation of the methods. DA - 2012/06/10 PY - 2012 PB - European Acoustic Association LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 19cc32d0-c11a-4abf-855e-df9c3d892a5e ER - TY - JOUR TI - Exploration of the relationship between water main breaks and temperature covariates DO - 10.1080/1573062X.2011.630093 AU - Rajani, B. B. AU - Kleiner, Y. AU - Sink, J-E. T2 - Urban Water Journal VL - 9 IS - 2 SP - 67 EP - 84 KW - ductile iron pipes, corrosion pit, pipe sampling, condition assessment KW - Water mains KW - Conduites d'eau AB - This paper examines the impact of temperature changes on observed pipe breakage rate for three pipe materials, namely, cast iron, ductile iron and galvanized steel. Several water and air temperature-based covariates were tested in conjunction with a non-homogeneous Poisson pipe break model to assess their impact on water main breaks, using data sets from three different water utilities in the USA and Canada. Temperature-based covariates, such as average mean air temperature, maximum air temperature increase and decrease, and how fast the air temperature increase and decrease over a specific period of days, were found to be consistently significant. While the availability of water temperature data (which most utilities do not have) can enhanced the prediction of water main breaks, it appears that air temperature data alone (which most utilities can access) are usually sufficient. DA - 2012/05/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7c91a647-aadd-40db-9701-39533b682647 ER - TY - JOUR TI - Hybrid fire testing of building structures AU - Mostafaei, H. T3 - 7th International Conference on Structures of Fire: 06 June 2012, Zurich, Switzerland SP - 1 EP - 8 KW - Hybrid test, performance-based assessment, fire resistance, numerical analysis, fire test building in fire KW - Design fires/Fire modeling KW - Conception d'incendies-types AB - A performance-based fire resistance evaluation method, called hybrid fire testing (HFT), was developed and carried out at the Fire Research Program of the National Research Council of Canada (NRC). HFT offers a more cost-effective approach to the assessment of the full structures performance in fire than that of a full-scale test and provides more reliable results than prescriptive single component testing. In the HFT method, the whole building is divided into two substructures; 1) the test specimen and 2) the model component. Then, fire performance of the whole structure is evaluated based on coupling the performance of the two substructures and by including their interactions in real time during the simulation. In this study, the HFT was applied for a 6-storey reinforced concrete building structure with a fire compartment scenario on the first floor. The test specimen was a worst-case scenario column in the compartment of fire origin in the building. The specimen was physically tested in a full-scale furnace, and the remaining of the building structure was modeled using numerical analysis software. In the HFT, the real time interactions between the two substructures are based not only on including the experimental results obtained from the test specimen into the numerical model component but most importantly also including feeding the output of the model component back into the test specimen environment (e.g. vertical and lateral loading changes). In other words, both equilibrium and compatibility conditions are satisfied between the test specimen and the model component. The results of this study show that the HFT is achievable and can be performed successfully for fire performance evaluation of a building structure. AB - Une méthode d?évaluation de la tenue au feu axée sur la performance, appelée méthode d?essai de résistance au feu hybride (ERFH), a été élaborée et mise en ?uvre au programme Recherche en incendie du Conseil national de recherches du Canada (CNRC). L?ERFH est une méthode plus efficace par rapport au coût pour évaluer la performance globale des structures exposées au feu, que celle de l?essai en vraie grandeur, et elle génère des résultats plus fiables que ceux des essais normatifs de composants isolés. Suivant la méthode ERFH, le bâtiment en entier est subdivisé en deux (2) structures secondaires : 1) le spécimen d?essai; et 2) le composant type. Ensuite, la tenue au feu de l?ensemble de la structure est évaluée en fonction du couplage de la performance des deux structures secondaires et en incluant leurs interactions en temps réel au cours de la simulation. Dans le cadre de cette étude, l?ERFH a été appliquée à une structure de bâtiment de six (6) étages en béton armé, avec un compartiment à l?épreuve du feu au rez-de-chaussée. Le spécimen d?essai était un poteau représentant le scénario de la pire éventualité dans le compartiment à l?épreuve du feu. Le spécimen a été mis à l?essai physiquement dans un four pleine grandeur, et le reste de la structure du bâtiment a été modélisé au moyen d?un logiciel d?analyse numérique. Dans l?ERFH, les interactions en temps réel entre les deux structures secondaires sont fondées non seulement sur l?inclusion des résultats expérimentaux obtenus à partir du spécimen d?essai et du modèle numérique du composant type, mais, ce qui le plus important, également en incluant la rétropropagation de la sortie du composant type dans l?environnement du spécimen d?essai (p. ex., changements aux niveaux des charges verticales et latérales). En d?autres mots, les conditions tant d?équilibre que de compatibilité sont obtenues entre le spécimen d?essai et le composant type. Les résultats de cette étude révèlent que l?ERFH peut être obtenue et réalisée avec succès aux fins de l?évaluation de la tenue au feu d?une structure de bâtiment. DA - 2012/06/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 686e0f1a-74e5-4588-896d-1be7ed30094c ER - TY - JOUR TI - Investigation of thermal performance of reflective insulations for different applications DO - 10.1016/j.buildenv.2011.12.010 AU - Saber, H. H. T2 - Journal of Building and Environment VL - 52 SP - 32 EP - 44 KW - Reflective insulation, furred-airspace assembly, low emissivity material, thermal modelling, thermal resistance test method, R-value, heat flow meter, ASTM C-518, ASTM C-1363, airflow, heat transfer by convection, conduction and radiation KW - Walls KW - Murs AB - In this study, the test data was obtained from a different test method based on the heat flow meter in accordance of ASTM C-518 in the case of horizontal sample stacks with reflective insulations. Results showed that the predicted heat fluxes on the same area and same location of Heat Flux Transducers (HFTs) on the top and bottom surfaces of the sample stacks are in good agreement with the measured heat fluxes (within ±1%). The derived R-values using these heat fluxes are also in good agreements. Due to the combined effect of heat transfer by convection and radiation in the airspace (facing the reflective surface), these predicted and measured heat fluxes are greater than the area-weighted average heat flux of whole sample stack, which is needed to determine the effective R-value of the sample. As such, the derived R-value from the test data resulted in underestimation of the effective R-value of the sample stack. After gaining confidence in the present model, it was used to conduct parametric study in order to quantify the contribution of reflective insulations to the effective R-value for a sample stack with different inclination angles, different directions of heat flow (upward and downward) and for a wide range of foil emissivity. Furthermore, the present model was used to compare the predicted R-values with the listed R-values in the 2009 ASHRAE Handbook [22] for enclosed air cavity (20 mm thick) of different effective emittance, inclinations and directions of heat flow. AB - Dans cette étude, les données d?essais ont été obtenues à partir d?une méthode d?essai différente fondée sur le fluxmètre thermique en conformité avec la norme ASTM C-518, dans le cas des empilages d?échantillons horizontaux avec isolants réfléchissants. Les résultats ont démontré que les flux thermiques prédits sur la même aire et au même emplacement des fluxmètres thermiques, sur les surfaces supérieure et inférieure des empilages d?échantillons, concordent de façon satisfaisante avec les flux thermiques mesurés (à ±1 % près), et il en va de même avec les valeurs « R » dérivées en utilisant ces flux thermiques. En raison de l?incidence combinée du transfert de chaleur par convection et du rayonnement dans la lame d?air (face à la surface réfléchissante), ces flux thermiques prédits et mesurés sont supérieurs aux flux thermiques moyens pondérés de l?aire pour l?empilage d?échantillons pris globalement, ce qui est nécessaire à la détermination de la valeur « R » effective de l?échantillon. À ce titre, la valeur « R » dérivée des données d?essai a donné lieu à une sous-estimation de la valeur « R » effective de l?empilage d?échantillons. Une fois notre confiance accrue dans le modèle actuel, celui-ci a pu être utilisé pour mener une étude paramétrique visant à quantifier l?apport des isolants réfléchissants à la valeur « R » effective pour un empilage d?échantillons présentant différents angles d?inclinaison et différentes directions de flux thermique (vers le haut et vers le bas) et pour une vaste gamme de valeurs d?émissivité de feuille métallique. En outre, on a utilisé le modèle actuel pour comparer les valeurs « R » prédites aux valeurs « R » répertoriées dans le 2009 ASHRAE Handbook relativement à la cavité d?air fermée (20 mm d?épaisseur), pour différentes émittances, inclinaisons et directions de flux thermique effectives. DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 43b81160-b3b7-4c3f-aa31-6e92adb9bc4a ER - TY - JOUR TI - Fire suppression performance of manually applied CAF and other water based systems AU - Kim, A. K. AU - Crampton, G. P. T3 - Suppression and Detection Research and Applications Symposium - SUPDET 2012: 05 March 2012, Phoenix, AZ SP - 1 EP - 7 KW - Fire KW - Incendie KW - Suppression KW - Extinction DA - 2012/03/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5828443a-43fe-4ba3-a12d-e8463b99cd96 ER - TY - JOUR TI - Multi-objective and probabilistic decision-making approaches to sustainable design and management of highway bridge decks DO - 10.1080/15732479.2012.657652 AU - Lounis, Z. AU - Daigle, L. T2 - Structure and Infrastructure Engineering (Special Issue on Asset Management) SP - 1 EP - 20 KW - Highway bridge decks KW - life cycle design KW - mechanistic service life models KW - social-economic-environmental performance KW - sustainable management KW - uncertainty modelling. KW - Concrete KW - Béton AB - In this paper, a simplified approach to sustainable design and management of highway bridge decks is proposed in which relevant data on some key social, economic and environmental performance measures are provided to support effective decision-making. The socioeconomic performance measures include physical condition of the deck, life cycle costs to owners and users, including accident costs, traffic delay costs and vehicle operating costs. The environmental performance measures include C02 emissions and construction waste. The proposed life cycle-based design and management approach is based on probabilistic mechanistic models that predict the time varying probabilities of chloride contamination, reinforcement corrosion, and corrosion -induced damage of the deck. The proposed approach is illustrated on the life cycle design and management of highway bridge decks using normal and high performance concrete. It is shown that high performance concrete decks outperform normal concrete decks in terms of longer service life, lower life cycle costs, and higher reductions in C02 emissions and waste materials. AB - Dans le cadre de ce document, on propose une approche simplifiée de la conception et de la gestion durables des tabliers de ponts routiers selon laquelle les données pertinentes liées à certaines mesures clés des performances sociale, économique et environnementale sont fournies à l?appui d?un processus décisionnel efficace. Les mesures de la performance socioéconomique incluent l?état physique du tablier, les coûts du cycle de vie pour les propriétaires et les usagers, y compris les coûts liés aux accidents, ceux liés aux retards dans l?écoulement du trafic et ceux liés à l?utilisation des véhicules automobiles. Les mesures environnementales de la performance incluent celles des émissions de C02 et des déchets de construction. L?approche suggérée pour la conception et la gestion fondées sur le cycle de vie a pour fondements les modèles probabilistes et mécanistes qui prédisent les probabilités temporalisées de la contamination par les chlorures, de la corrosion des armatures et de l?endommagement causé par la corrosion du tablier. L?approche proposée est illustrée relativement à la conception et à la gestion du cycle de vie des tabliers de ponts routiers utilisant du béton ordinaire et du béton à hautes performances. Il est démontré que les tabliers construits en béton à hautes performances offrent une vie utile plus longue, des coûts de cycle de vie inférieurs et des réductions marquées d?émissions de C02 et de déchets de construction par rapport aux tabliers en béton ordinaire. DA - 2012/02/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 644f500d-424b-4f8f-8e8b-af958cc98276 ER - TY - JOUR TI - Evaluation of the fire suppression effectiveness of manually applied compressed-air-foam (CAF) system DO - 10.1007/s10694-009-0119-3 AU - Kim, A. K. AU - Crampton, G. P. T2 - Fire Technology VL - 48 IS - 3 SP - 549 EP - 564 KW - Fire KW - Incendie KW - Suppression KW - Extinction DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0888ccda-5a6c-49f2-aa30-e0954e788cd7 ER - TY - JOUR TI - Design fires for road tunnels safety design AU - Kashef, A. AU - Viegas, J. AU - Mos, A. AU - Harvey, N. T2 - ASHRAE Transactions T2 - ASHRAE Transactions T3 - ASHRAE Annual Meeting: 21 January 2012, Chicago, Illinois SN - 0001-2505 SN - 9781936504220 VL - 118 IS - 1 SP - 636 EP - 643 KW - Design fires/Fire modeling KW - Conception d'incendies-types AB - Design fires are an intrinsic part in designing tunnels for fires. They provide, quantitatively, the fire characteristics that are used to establish the sizing of equipment in tunnels and the scenarios to consider when developing emergency response plans. They are also used, indirectly, when considering the impact of fires on the structure. As such, design fires form the base input for emergency ventilation, evacuation, and structural design analyses. A design fire is generally defined in terms of heat release rate, and species output as functions of time. This paper summarizes efforts to develop a set of design fire curves as a useful tool for road tunnel fire risk assessment. AB - Les incendies types de conception font partie intrinsèque de l?étude des tunnels en termes de résistance aux incendies. Ils fournissent quantitativement les caractéristiques de tenue au feu qui sont employées aux fins de l?établissement des dimensions de l?équipement dans les tunnels et des scénarios à prendre en compte dans la mise au point de plans d?intervention en cas d?urgence. On utilise également les incendies types de conception, indirectement, pour évaluer l?incidence des incendies sur la structure même. À ce titre, les incendies types de conception constituent les données d?entrée de base dans les analyses de la ventilation en cas d?urgence, de l?évacuation et de la conception des structures des tunnels. Un incendie type de conception est généralement défini en termes de débit calorifique et de production d?espèces chimiques comme fonctions du temps. Ce document résume les efforts consacrés à la création d?un ensemble de courbes d?incendie type de conception en tant qu?outil d?évaluation des risques associés aux incendies dans les tunnels autoroutiers. DA - 2012/01/21 PY - 2012 PB - American Society of Heating, Refrigerating and Air-Conditioning Engineers LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 15a6f36f-7c94-4f3a-a3b2-031e7681f833 ER - TY - JOUR TI - Federal investigation of the evacuation of the World Trade Centre on September 11, 2001 DO - 10.1002/fam.2162 AU - Averill, Jason D. AU - Mileti, D. AU - Peacock, R. AU - Kuligowski, E. AU - Groner, N. AU - Proulx, G. AU - Reneke, P. AU - Nelson, H. T2 - Fire and Materials T3 - 4th International Symposium on Human Behaviour in Fire, 13 July 2009, Robinson College, Cambridge, UK VL - 36 IS - 5-6 SP - 472 EP - 480 KW - evacuation; human behaviour; world trade center KW - Comportement humain KW - World Trade Centre DA - 2012/07/24 PY - 2012 PB - Wiley LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4d87afc6-a5cc-4355-a1fd-9e2204ba8651 ER - TY - JOUR TI - Decarboxylation-induced cross-linking of polymers of intrinsic microporosity (PIMs) for membrane gas separation DO - 10.1021/ma300751s AU - Du, Naiying AU - Dal-Cin, Mauro M. AU - Robertson, Gilles P. AU - Guiver, Michael D. T2 - Macromolecules VL - 45 IS - 12 SP - 5134 EP - 5139 KW - cross-linked membranes KW - gas separation KW - C-PIMs KW - decarboxylation KW - carboxylated PIMs KW - polymers of intrinsic microporosity KW - fourier transform infrared spectroscopy KW - FTIR DA - 2012/06/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9a9d6fd3-d4ab-43b1-ad49-714160170781 ER - TY - JOUR TI - Mining biological information from 3D gene expression data : the OPTricluster algorithm DO - 10.1186/1471-2105-13-54 AU - Tchagang, Alain B. AU - Phan, Sieu AU - Famili, Fazel AU - Shearer, Heather AU - Fobert, Pierre AU - Huang, Yi AU - Zou, Jitao AU - Huang, Daiqing AU - Cutler, Adrian AU - Liu, Ziying AU - Pan, Youlian T2 - BMC Bioinformatics 2012 VL - 13 SP - 54 AB - Background: Nowadays, it is possible to collect expression levels of a set of genes from a set of biological samples during a series of time points. Such data have three dimensions: gene-sample-time (GST). Thus they are called 3D microarray gene expression data. To take advantage of the 3D data collected, and to fully understand the biological knowledge hidden in the GST data, novel subspace clustering algorithms have to be developed to effectively address the biological problem in the corresponding space. DA - 2012/04/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 23c1f50e-c76a-4c55-9354-84e8181343f4 ER - TY - JOUR TI - Ecological validity and the evaluation of speech summarization quality AU - McCallum, Anthony AU - Munteanu, Cosmin AU - Penn, Gerald AU - Zhu, Xiaodan T2 - Proceeding of the Workshop on Evaluation Metrics and System Comparison for Automatic Summarization T3 - NAACL-HLT 2012 Workshop on Evaluation Metrics and System Comparison for Automatic Summarization, Montreal, Quebec, Canada, 3-8 June 2012 SN - 978-1-937284-20-6 SP - 28 EP - 35 AB - There is little evidence of widespread adoption of speech summarization systems. This may be due in part to the fact that the natural language heuristics used to generate summaries are often optimized with respect to a class of evaluation measures that, while computationally and experimentally inexpensive, rely on subjectively selected gold standards against which automatically generated summaries are scored. This evaluation protocol does not take into account the usefulness of a summary in assisting the listener in achieving his or her goal. In this paper we study how current measures and methods for evaluating summarization systems compare to human-centric evaluation criteria. For this, we have designed and conducted an ecologically valid evaluation that determines the value of a summary when embedded in a task, rather than how closely a summary resembles a gold standard. The results of our evaluation demonstrate that in the domain of lecture summarization, the wellknown baseline of maximal marginal relevance (Carbonell and Goldstein, 1998) is statistically significantly worse than human-generated extractive summaries, and even worse than having no summary at all in a simple quiz-taking task. Priming seems to have no statistically significant effect on the usefulness of the human summaries. In addition, ROUGE scores and, in particular, the contextfree annotations that are often supplied to ROUGE as references, may not always be reliable as inexpensive proxies for ecologically valid evaluations. In fact, under some conditions, relying exclusively on ROUGE may even lead to scoring human-generated summaries that are inconsistent in their usefulness relative to using no summaries very favourably. DA - 2012/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 55ccecc7-a877-4f4e-a5bc-da5e66b948c2 ER - TY - JOUR TI - On hierarchical re-ordering and permutation parsing for phrase-based decoding AU - Cherry, Colin AU - Moore, Robert C. AU - Quirk, Chris T2 - Proceedings of the 7th Workshop on Statistical Machine Translation (WMT 2012) T3 - NAACL 2012 Workshop on Statistical Machine Translation (WMT 2012), Montreal, QC, June 7-8, 2012 SP - 200 EP - 209 AB - The addition of a deterministic permutation parser can provide valuable hierarchical information to a phrase-based statistical machine translation (PBSMT) system. Permutation parsers have been used to implement hierarchical re-ordering models (Galley and Manning, 2008) and to enforce inversion transduction grammar (ITG) constraints (Feng et al., 2010). We present a number of theoretical results regarding the use of permutation parsers in PBSMT. In particular, we show that an existing ITG constraint (Zens et al., 2004) does not prevent all non-ITG permutations, and we demonstrate that the hierarchical reordering model can produce analyses during decoding that are inconsistent with analyses made during training. Experimentally, we verify the utility of hierarchical re-ordering, and compare several theoretically-motivated variants in terms of both translation quality and the syntactic complexity of their output. DA - 2012/06/08 PY - 2012 PB - Association for Computational Linguistics LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4438fa9d-94ad-4f4b-85d7-e8dc91e0013b ER - TY - JOUR TI - Binary classifiers and latent sequence models for emotion detection in suicide notes DO - 10.4137/BII.S8933 AU - Cherry, Colin AU - Mohammad, Saif M. AU - de Bruijn, Berry T2 - Biomedical Informatics Insights VL - 5 IS - Supplement 1 SP - 147 EP - 154 AB - This paper describes the National Research Council of Canada’s submission to the 2011 i2b2 NLP challenge on the detection of emotions in suicide notes. In this task, each sentence of a suicide note is annotated with zero or more emotions, making it a multi-label sentence classification task. We employ two distinct large-margin models capable of handling multiple labels. The first uses one classifier per emotion, and is built to simplify label balance issues and to allow extremely fast development. This approach is very effective, scoring an F-measure of 55.22 and placing fourth in the competition, making it the best system that does not use web-derived statistics or re-annotated training data. Second, we present a latent sequence model, which learns to segment the sentence into a number of emotion regions. This model is intended to gracefully handle sentences that convey multiple thoughts and emotions. Preliminary work with the latent sequence model shows promise, resulting in comparable performance using fewer features. DA - 2012/01/30 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9d8c88cd-dd46-4c75-96fc-63bdb095b3c4 ER - TY - JOUR TI - Cybersickness induced by desktop virtual reality AU - Vinson, Norman G. AU - Lapointe, Jean-Francois AU - Parush, Avi AU - Roberts, Shelley T2 - Proceedings Graphics Interface 2012 T3 - 38th Graphics Interface Conference (GI 2012), May 28-30, 2012, Toronto, Ontario, Canada SN - 0713-5424 SN - 9781450314206 SP - 69 EP - 75 KW - Cybersickness KW - simulator sickness KW - screening KW - desktop KW - liability KW - ethics AB - Cybersickness, a syndrome resulting from exposure to virtual reality displays, raises ethical and liability issues. We have found that, contrary to the majority of previous reports in the literature, cybersickness can be induced by desktop virtual real-ity. Moreover, our findings suggest that some individuals susceptible to cybersickness can be screened out on the basis of their self-reported susceptibility to motion sickness. DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : aa9661c8-91d9-49d9-bb47-a27a194e454f ER - TY - JOUR TI - Portable features for classifying emotional text AU - Mohammad, Saif T2 - Proceedings of The 2012 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies (NAACL:HLT-2012), Montreal, QC, June 3-8, 2012 T3 - The 2012 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies (NAACL:HLT-2012), Montreal, Canada, June 3-8, 2012 SP - 587 EP - 591 AB - Are word-level affect lexicons useful in detecting emotions at sentence level? Some prior research finds no gain over and above what is obtained with ngram features-arguably the most widely used features in text classification. Here, we experiment with two very different emotion lexicons and show that even in supervised settings, an affect lexicon can provide significant gains. We further show that while ngram features tend to be accurate, they are often unsuitable for use in new domains. On the other hand, affect lexicon features tend to generalize and produce better results than ngrams when applied to a new domain. DA - 2012/06/08 PY - 2012 PB - Association for Computational Linguistics LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5e92e488-20af-489f-ae82-c55c0f4fa395 ER - TY - JOUR TI - Batch tuning strategies for statistical machine translation AU - Cherry, Colin AU - Foster, George T2 - Proceedings of the 2012 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies - (HLT-NAACL 2012) T3 - North American Chapter of the Association for Computational Linguistics: Human Language Technologies - (HLT-NAACL 2012), Montreal, QC, June 3-8, 2012 SP - N12-1047 SP - 427 EP - 436 AB - There has been a proliferation of recent work on SMT tuning algorithms capable of handling larger feature sets than the traditional MERT approach. We analyze a number of these algorithms in terms of their sentence-level loss functions, which motivates several new approaches, including a Structured SVM. We perform empirical comparisons of eight different tuning strategies, including MERT, in a variety of settings. Among other results, we find that a simple and efficient batch version of MIRA performs at least as well as training online, and consistently outperforms other options. DA - 2012/06/08 PY - 2012 PB - Association for Computational Linguistics LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1101df04-9f92-4758-a257-3a8457183e06 ER - TY - JOUR TI - A methodology for composing behaviour models for military simulations AU - Unrau, David P. AU - Emond, Bruno T2 - 21st Annual Conference on Behavior Representation in Modeling and Simulation (BRiMS 2012) T3 - 21st Annual Conference on Behavior Representation in Modeling and Simulation 2012, BRiMS 2012, March 12-15, 2012, Amelia Island, FL, USA SN - 9781622761739 SN - 1622761731 SP - 213 EP - 214 KW - Decision-making KW - Ontology KW - Military Simulation KW - Standardization DA - 2012/03/15 PY - 2012 PB - IEEE Computer Society LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8b05bbc8-730d-4d19-9b99-13f9e9401596 ER - TY - JOUR TI - Fractal geometry and multimedia retrieval: a theoretical framework AU - Paquet, Eric AU - Viktor, Herna L. T2 - 3D Image Processing (3DIP) and Applications 2012 Conference Proceedings T2 - Proceedings of SPIE; 8290 T3 - 3D Image Processing (3DIP) and Applications 2012, San Francisco Airport, Burlingame, California, 22-26 January 2012 KW - Bayesian KW - distance KW - distribution KW - fractal KW - geometry KW - indexing KW - Lagrangian KW - multimedia KW - object KW - probability KW - retrieval AB - This paper presents a theoretical analysis of the occurrence of fractal geometry within index spaces and discusses the impact for multimedia retrieval. Firstly, we explain how to detect the presence of such a fractal geometry. Then, with the fractal hypothesis in hand, we analyze the impact of this geometry when calculating the distance between indexes and searching for similar multimedia objects. We demonstrate that it is possible to define probability distributions in fractal index space and we present an approach to calculate them. Practical consequences are discussed, with particular emphasis to multimedia retrieval methods based on Bayesian analysis. DA - 2012/02 PY - 2012 PB - SPIE PB - SPIE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5ad6b425-48bd-4c37-94fd-597aa8bdf79d ER - TY - JOUR TI - Cognitive modelling of early music reading skill acquisition for piano AU - Emond, Bruno AU - Comeau, Gilles T2 - Proceedings of the 11th International Conference on Cognitive Modeling (ICCM 2012) T3 - ICCM 2012: International Conference on Cognitive Modeling, Berlin, Germany, April 13-15, 2012 SP - 43 EP - 48 KW - Music reading KW - piano methods KW - ACT-R AB - In the classical music tradition, knowing how to read music is an essential skill and is seen as a fundamental component to develop when learning to play the piano. This research's focus is to study the possible impact of the different teaching approach on the acquisition of initial reading skills. By using cognitive modeling, we are hoping to observe through computer simulation the problem solving and decisionmaking tasks involved in decoding a simple musical score. The paper introduces the Middle-C and Intervallic methods followed by a description of an ACT-R cognitive model and simulation results upon learning with each of the piano methods. DA - 2012/04/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e89c9706-546e-4ee0-b7bb-4a67c90fc30b ER - TY - JOUR TI - A tale of two studies: challenges in field research with low-literacy adult learners in a developed country DO - 10.1145/2212776.2212825 AU - Munteanu, Cosmin AU - Molyneaux, Heather AU - Maitland, Julie AU - McDonald, Daniel AU - Leung, Rock T2 - CHI 2012: Proceedings of the 2012 ACM annual conference extended abstracts on Human Factors in Computing Systems T3 - The 2012 ACM SIGCHI Conference on Human Factors in Computing Systems (CHI 2012), Austin, Texas, May 5-10, 2012 SN - 978-1-4503-1016-1 SP - 489 EP - 504 KW - User studies KW - evaluation methodology KW - mobile computing KW - interface design KW - educational interfaces KW - mobile learning KW - assistive technology AB - Efforts to address the problems of literacy are often focused on developing countries. However, functional illiteracy is a challenge encountered by up to 50 percent of adults in developed countries. In this paper we reflect on the challenges we faced in trying to design and study the use of a mobile application to support adult literacy with two user groups: adults enrolled in literacy classes and carpenters without a high school education enrolled in an essential skills program. We also elaborate on aspects of the evaluations that are specific to a marginalized, functionally illiterate, group in a developed country – aspects that are less frequently present in similar studies of mobile literacy support technologies in developing countries. We conclude with presenting the lessons learnt from our evaluations and the impact of the studies' specific challenges on the outcome and uptake of such mobile assistive technologies in providing practical support to low-literacy adults in conjunction with literacy and essential skills training. DA - 2012/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d96f1ee3-f11d-4915-b932-1fa786547efc ER - TY - CHAP TI - Cost-sensitive self-training DO - 10.1007/978-3-642-30353-1_7 AU - Guo, Yuanyuan AU - Zhang, Harry AU - Spencer, Bruce T2 - Advances in Artificial Intelligence : 25th Canadian Conference on Artificial Intelligence, Canadian AI 2012, Toronto, ON, Canada, May 28-30, 2012. Proceedings T2 - Lecture Notes In Computer Science; 7310 T3 - 25th Canadian Conference on Artificial Intelligence (Canadian AI 2012), May 28-30, 2012, Toronto, Ontario, Canada SN - 0302-9743 SN - 978-3-642-30352-4 SN - 978-3-642-30353-1 SP - 74 EP - 84 KW - self-training KW - cost-sensitive KW - Naive Bayes AB - In some real-world applications, it is time-consuming or expensive to collect much labeled data, while unlabeled data is easier to obtain. Many semi-supervised learning methods have been proposed to deal with this problem by utilizing the unlabeled data. On the other hand, on some datasets, misclassifying different classes causes different costs, which challenges the common assumption in classification that classes have the same misclassification cost. For example, misclassifying a fraud as a legitimate transaction could be more serious than misclassifying a legitimate transaction as fraudulent. In this paper, we propose a cost-sensitive self-training method (CS-ST) to improve the performance of Naive Bayes when labeled instances are scarce and different misclassification errors are associated with different costs. CS-ST incorporates the misclassification costs into the learning process of self-training, and approximately estimates the misclassification error to help select unlabeled instances. Experiments on 13 UCI datasets and three text datasets show that, in terms of the total misclassification cost and the number of correctly classified instances with higher costs, CS-ST has better performance than the self-training method and the base classifier learned from the original labeled data only. DA - 2012/05/30 PY - 2012 PB - Springer Berlin Heidelberg LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 837610f2-a9d8-400f-9edf-f93bce3f74d5 ER - TY - JOUR TI - An ecologically valid evaluation of speech summarization DO - 10.1145/2212776.2223779 AU - McCallum, Anthony AU - Munteanu, Cosmin AU - Penn, Gerald AU - Zhu, Xiaodan T2 - CHI 2012: Proceedings of the 2012 ACM annual conference extended abstracts on Human Factors in Computing Systems T3 - ACM SIGCHI Conference on Human Factors in Computing Systems, Austin, Texas, USA, May 5-10, 2012 SN - 978-1-4503-1016-1 SP - 2219 EP - 2224 KW - Speech summarization KW - user study KW - extrinsic evaluation AB - The past decade has witnessed an explosion in the size and availability of online audio-visual repositories, such as entertainment, news, or lectures. Summarization systems have the potential to provide significant assistance with navigating such repositories. Unfortunately, automatically-generated summaries often fall short of delivering the information needed by users. This is due, in no small part, to the fact that the natural language heuristics used to generate summaries are often optimized with respect to currently-used evaluation metrics. Such metrics simply score automaticallygenerated summaries against subjectively-classified gold standards without taking into account the usefulness of a summary in assisting a user achieve a certain goal or even overall summary coherence. We have previously shown that an immediate consequence of this problem is that even the most linguistically-complex summarization systems perform no better than basic heuristics, such as picking the longest sentences from a general-topic, spontaneous dialog, or the first few sentences from a news recording. Our hypothesis is that complex systems are in fact better, if measured properly. What is thus needed instead are evaluation metrics (and consequently, automatic summarizers) that incorporate features such as user preferences and task-orientation. For this, we propose an ecologically valid evaluation metric that determines the value of a summary when embedded in a task, rather than how closely a summary matches a gold standard. DA - 2012/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c3d41365-ca29-4a69-b939-bb6d93195ce6 ER - TY - JOUR TI - Improving AMBER, an MT Evaluation Metric AU - Chen, Boxing AU - Kuhn, Roland AU - Foster, George T2 - NAACL 2012 Workshop on Statistical Machine Translation: (WMT-2012) T3 - 7th Workshop on Statistical Machine Translation (WMT 2012), June 7-8, 2012, Montréal, QC, Canada SN - 978-1-937284-20-6 SP - 59 EP - 63 AB - A recent paper described a new machine translation evaluation metric, AMBER. This paper describes two changes to AMBER. The first one is incorporation of a new ordering penalty; the second one is the use of the downhill simplex algorithm to tune the weights for the components of AMBER. We tested the impact of the two changes, using data from the WMT metrics task. Each of the changes by itself improved the performance of AMBER, and the two together yielded even greater improvement, which in some cases was more than additive. The new version of AMBER clearly outperforms BLEU in terms of correlation with human judgment. DA - 2012/06/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a0fb52ca-4e0d-49b5-9ba8-e34401cc787d ER - TY - JOUR TI - Near-infrared fluorescence imaging of mouse myocardial microvascular endothelium using Cy5.5-lectin conjugate DO - 10.1002/jbio.201100119 AU - Nguyen, Cecilia AU - Bascaramurty, Saro AU - Kuzio, Bozena AU - Gregorash, Lori AU - Kupriyanov, Valery AU - Jilkina, Olga T2 - Journal of Biophotonics KW - Cy5.5 KW - Lycopersicon esculentum lectin KW - mouse KW - fluorescence microscopy KW - cardiac imaging techniques KW - endothelial cells AB - Cy5.5-lectin, a non-toxic conjugate, combines the benefits of near-infrared (NIR) imaging, such as significant reduction of background fluorescence and increased tissue depth penetration, with its affinity for vascular endothelial cells. When compared to endothelial staining methods using FITC-lectin and ICAM2 antibodies, Cy5.5-lectin was confirmed to specifically bind endothelial cells and produce a fluorescence signal both in real-time and post-infusion. Ex-vivo experiments with isolated hearts demonstrated that binding was limited to perfused areas of the myocardium. With mouse in-vivo tail-vein injections, other organs such as the liver, spleen, and kidney were also stained and yielded similar quality images of the heart. DA - 2012/02/27 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1c95b0f7-5e26-4bcd-a613-ea22082a1b4b ER - TY - JOUR TI - One test microbial diagnostic microarray for identification of Mycoplasma mycoides subsp. mycoides and other Mycoplasma species DO - 10.1007/s12033-012-9497-8 AU - Tonelli, A. AU - Sacchini, F. AU - Krasteva, I. AU - Zilli, K. AU - Scacchia, M. AU - Beaurepaire, C. AU - Nantel, A. AU - Pini, A. T2 - Molecular Biotechnology KW - Diagnosis KW - Microarray KW - Mycoplasma: Contagious bovine pleuropneumonia KW - Mycoplasma mycoides subsp. Mycoides KW - Cluster analysis AB - The present study describes the use of microarray technology for rapid identification and differentiation of Mycoplasma mycoides subsp. mycoides from other mycoplasmas that may be pathogenic to ruminants, including those of the Mycoplasma mycoides cluster, genetically and antigenically strictly correlated with Mycoplasma mycoides subsp. mycoides. A microarray containing genetic sequences of 55 different bacterial species from Acholeplasma, Mycoplasma, Spiroplasma and Ureaplasma genera was constructed. Sequences to genes of interest were collected in FASTA format from NCBI. The collected sequences were processed with OligoPicker software. Oligonucleotides were then checked for their selectivity with BLAST searches in GenBank. The microarray was tested with ATCC/NCTC strains of Mycoplasma spp. of veterinary importance in ruminants including Mycoplasma belonging to the mycoides cluster as well as Mycoplasma mycoides subsp. mycoides and Mycoplasma mycoides subsp. capri field strains. The results showed that but one ATCC/NCTC reference strains hybridized with their species-specific sequences showed a profile/signature different and distinct from each other. The heat-map of the hybridization results for the nine genes interrogated for Mycoplasma mycoides subsp. mycoides demonstrated that the reference strain Mycoplasma mycoides subsp mycoides PG1 was positive for all of the gene sequences spotted on the microarray. CBPP field, vaccine and reference strains were all typed to be M. mycoides subsp. mycoides, and seven of the nine strains gave positive hybridization results for all of the nine genes. Two Italian strains were negative for some of the genes. Comparison with non-Mycoplasma mycoides subsp. mycoides reference strains showed some positive signals or considerable homology to Mycoplasma mycoides subsp. mycoides genes. As expected, some correlations were observed between the strictly genetically and antigenically correlated Mycoplasma mycoides subsp. mycoides and Mycoplasma mycoides subsp. capri strains. Specifically, we observed that some Italian Mycoplasma mycoides subsp. mycoides strains were positive for two out of the three Mycoplasma mycoides subsp. capri genes, differently from what has been observed for other European or African Mycoplasma mycoides subsp. mycoides strains. This study highlighted the use of microarray technology as a simple and effective method for a single-step identification and differentiation of Mycoplasma mycoides subsp. mycoides from other mycoplasmas that may be pathogenic to ruminants, including those of the Mycoplasma mycoides cluster, genetically and antigenically strictly correlated with Mycoplasma mycoides subsp. mycoides. The opportunity to discriminate several mycoplasmas in a single analysis enhances diagnostic rapidity and may represent a useful tool to screen occasionally mycoplasmas affecting animal farming in territories where diagnostic laboratory support is limited. The heat-map of the hybridization results of the comparative genomic hybridizations DNA-designed chip clearly indicates that the microarray performs well for the identification of the tested Mycoplasma mycoides subsp. mycoides reference and field strains, discriminating them from other mycoplasmas. DA - 2012/01/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2a1ae2a3-17a8-4482-aa69-e64ed133fa54 ER - TY - JOUR TI - Cloning, Baeyer-Villiger biooxidations, and structures of the camphor pathway 2-Oxo-Δ3-4,5,5-Trimethylcyclopentenylacetyl-Coenzyme A monooxygenase of Pseudomonas putida ATCC 17453 DO - 10.1128/AEM.07694-11 AU - Leisch, Hannes AU - Shi, Rong AU - Grosse, Stephan AU - Morley, Krista AU - Bergeron, Hélène AU - Cygler, Miroslaw AU - Iwaki, Hiroaki AU - Hasegawa, Yoshie AU - Lau, Peter C. K. T2 - Applied and Environmental Microbiology VL - 78 IS - 7 SP - 2200 EP - 2212 AB - A dimeric Baeyer-Villiger monooxygenase (BVMO) catalyzing the lactonization of 2-oxo-Δ3-4,5,5-trimethylcyclopentenylacetyl-CoA, a key intermediate in the metabolism of camphor by Pseudomonas putida ATCC 17453 had been initially characterized in 1983 by Trudgill and co-workers (H.J. Ougham, D.G. Taylor, and P.W. Trudgill, J. Bacteriol. 153:140-152, 1983). Here we have cloned and overexpressed the 2-oxo-Δ3-4,5,5-trimethylcyclopentenylacetyl-CoA monooxygenase (OTEMO) in Escherichia coli, and determined its three-dimensional structure with bound FAD at 1.95 Å resolution as well as with bound FAD and NADP+ at 2.0 Å resolution. OTEMO represents the first homodimeric type 1 BVMO structure bound to FAD/NADP+. Comparison of several crystal forms of OTEMO bound to FAD and NADP+ revealed conformational plasticity of several loop regions, some of which have been implicated as contributing to the substrate specificity profile of structurally-related BVMOs. Substrate specificity studies confirmed that the 2-oxo-Δ3-4,5,5-trimethylcyclopentenylacetic acid coenzyme A ester is preferred over the free acid. However, the catalytic efficiency (kcat/Km) favors 2-n-hexyl cyclopentanone (4.3 × 105 M−1s−1) as a substrate, although its affinity (Km = 32 μM) was lower than that of the CoA-activated substrate (18 μM). In whole cell biotransformation experiments, OTEMO showed a unique enantiocomplementarity to the action of the prototypical cyclohexanone monooxygenase (CHMO), and appeared to be particularly useful for the oxidation of 4-substituted cyclohexanones. Overall, this work expands our understanding of the molecular structure and mechanistic complexity of the type 1 family of BVMOs as well as expanding the catalytic repertoire of one of its original members. DA - 2012/01/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8e280ea6-d150-4e2b-a1c7-a2cf5b8cc571 ER - TY - CHAP TI - Polymers in membrane electrode assemblies DO - 10.1016/B978-0-444-53349-4.00287-9 AU - Kim, D. S. AU - Welch, C. AU - Hjelm, R. P. AU - Kim, Y. S. AU - Guiver, M. D. T2 - Polymers for a Sustainable Environment and Green Energy T2 - Polymer Science: A Comprehensive Reference; 10 SP - 691 EP - 720 KW - Dispersion KW - Electrode KW - Ion exchange capacity (IEC) KW - Ionomer KW - Hydrophilicity KW - Hydrophobicity KW - Interface KW - Membrane electrode assembly (MEA) KW - Methanol permeability KW - Perfluorosulfonic acid (PFSA) KW - Polarization curve KW - Proton conductivity KW - Proton exchange membrane (PEM) KW - Water uptake AB - This chapter is devoted to polymer electrolytes for use in membrane electrode assemblies of proton exchange membrane fuel cells. This chapter starts with a discussion of structure–property relationships of polymer electrolytes used as proton exchange membranes, in terms of water uptake, conductivity, and methanol permeability. The second part discusses polymer electrolytes used as electrode ionomers, specifically the structural effects of ionomer composition, ion exchange capacity, hydrophobicity, and dispersing solvent on fuel cell performance. The issue of interfacial compatibility between membrane and electrode is also discussed. DA - 2012/05/30 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 75edef54-f705-43eb-92e8-dd6f4be2da65 ER - TY - JOUR TI - Photoinduced band gap shift and deep levels in luminescent carbon nanotubes DO - 10.1021/nn204679s AU - Finnie, Paul AU - Lefebvre, Jacques T2 - ACS Nano VL - 6 IS - 2 SP - 1702 EP - 1714 KW - single-walled carbon nanotube KW - photoluminescence KW - exciton KW - quantum efficiency KW - band gap shift KW - van der Waals interaction AB - Individual air-suspended single-walled carbon nanotubes are imaged both spatially and spectrally in photoluminescence. At low excitation power, photoluminescence is bright and stable with high quantum efficiency; however, higher power initially causes a gradual red shift and then more severe changes. Blinking, the loss of quantum efficiency, and the appearance of new deep levels are all seen and can be explained by the introduction of defects. We propose that optical excitation induces molecular deposition onto the nanotube by optically induced van der Waals interactions, leading to physisorption and ultimately chemisorption which severely degrades the luminescence. DA - 2012/02/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1bf2b3ba-3f79-427b-9010-af2e7ce9a834 ER - TY - JOUR TI - Engineering and therapeutic application of single-chain bivalent TGF-β family traps DO - 10.1158/1535-7163.MCT-12-0060 AU - Zwaagstra, John C. AU - Sulea, Traian AU - Baardsnes, Jason AU - Lenferink, Anne E. G. AU - Collins, Cathy AU - Cantin, Christiane AU - Paul-Roc, Béatrice AU - Grothe, Suzanne AU - Hossain, Sazzad AU - Richer, Louis-Philippe AU - L'Abbé, Denis AU - Tom, Roseanne AU - Cass, Brian AU - Durocher, Yyves AU - O'Connor-McCourt, Maureen D. T2 - Molecular Cancer therapeutics SP - MCT-12-0060-1 EP - MCT-12-0060-31 KW - TGF-β family receptors: molecular design KW - traps KW - therapy KW - cancer AB - Deregulation of TGF-β superfamily signaling is a causative factor in many diseases. Here we describe a protein engineering strategy for the generation of single-chain bivalent receptor traps for TGF-β superfamily ligands. Traps were assembled using the intrinsically disordered regions flanking the structured binding domain of each receptor as "native linkers" between two binding domains. This yields traps that are approximately threefold smaller than antibodies and consists entirely of native receptor sequences. Two TGF-β type II receptor-based, single-chain traps were designed, termed (TβRII)2 and (TβRIIb)2, that have native linker lengths of 35 and 60 amino acids, respectively. Both single-chain traps exhibit a 100 to 1,000 fold higher in vitro ligand binding and neutralization activity compared with the monovalent ectodomain (TβRII-ED), and a similar or slightly better potency than pan–TGF-β–neutralizing antibody 1D11 or an Fc-fused receptor trap (TβRII-Fc). Despite its short in vivo half-life (<1 hour), which is primarily due to kidney clearance, daily injections of the (TβRII)2 trap reduced the growth of 4T1 tumors in BALB/c mice by 50 percent, an efficacy that is comparable with 1D11 (dosed thrice weekly). In addition, (TβRII)2 treatment of mice with established 4T1 tumors (100 mm3) significantly inhibited further tumor growth, whereas the 1D11 antibody did not. Overall, our results indicate that our rationally designed bivalent, single-chain traps have promising therapeutic potential. DA - 2012/05/04 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 59aa1f63-b3d4-469b-945c-03ed9d5b9f9a ER - TY - JOUR TI - PalI domain protiens of Saccharomyces cerevisiae and Candida albicans DO - 10.1016/j.micres.2011.12.005 AU - Yan, Lan AU - Côte, Pierre AU - Li, Xing-Xing AU - Jiang, Yuan-Ying AU - Whiteway, Malcolm T2 - Microbiological Research VL - 167 IS - 7 SP - 422 EP - 432 KW - PalI domain KW - Candida albicans KW - Saccharomyces cerevisiae KW - Environmental stress response AB - The Rim9/PalI groups of proteins are members of the Sur7 family, all of which contain a signal sequence and a block of three potential trans-membrane helices. Multi-protein sequence comparisons among fungi suggest that there are two classes of Rim9/PalI proteins; longer proteins like PalI that contain a Sur7 domain and a C-terminal extension, and shorter proteins like Rim9 that contain essentially only the Sur7 domain. We have examined possible roles of the longer, PalI-like proteins of both Saccharomyces cerevisiae (Yol019w) and Candida albicans (Orf19.1510/Srd1), two species that also contain short Rim9 proteins required for alkaline-associated stress responses. Deletions of the long form genes did not create any significant stress response phenotype in either S. cerevisiae or C. albicans, nor did the deletions enhance any of the rim9 deletion effects when combined in a double mutant. Furthermore, challenges in C. albicans show RIM9 but not SRD1 is important for proper response and hyphal formation. It appears that in fungal species such as Aspergillus nidulans containing only a long-form PalI-like protein, this element functions in the process of stress response, while in fungi with both versions the response to stress function is limited to the short-form protein. DA - 2012/02/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fe6bbc1a-70e1-4125-b79b-d5fe8bb771a0 ER - TY - JOUR TI - Molecular imaging of breast tumors using a near-infrared fluorescently labeled clusterin binding peptide DO - 10.1002/ijc.27368 AU - Filfil, Rana AU - Paul-Roc, Béatrice AU - Cantin, Christiane AU - Iqbal, Umar AU - Tolkatchev, Dmitri AU - Vinogradova, Anna AU - Xu, Ping AU - Ni, Feng AU - O'Connor-McCourt, Maureen D. AU - Lenferink, Anne E. G. T2 - International Journal of Cancer VL - 131 IS - 5 SP - E681 EP - E692 KW - secreted clusterin KW - 4T1 KW - time-domain near-infrared fluorescence imaging KW - binding peptide KW - breast cancer AB - Several reports have shown that secreted clusterin (sCLU) plays multiple roles in tumor development and metastasis. Here, we report on a 12-mer sCLU binding peptide (designated P3378) that was identified by screening a phage-display peptide library against purified human sCLU. Differential resonance perturbation nuclear magnetic resonance using P3378 and a scrambled control peptide (designated P3378R) confirmed the P3378-sCLU interaction and demonstrated that it was sequence specific. P3378 and P3378R peptides were conjugated to an Alexa680 near infrared fluorophore (NIRF) and assessed for their tumor homing abilities in in vivo time-domain fluorescence optical imaging experiments using living 4T1 tumor bearing BALB/c mice. When injected in separate animals, both peptides accumulated at the tumor site, however the NIRF-labeled P3378 peptide was retained for a significant longer period of time than the P3378R peptide. Similar observations were made after simultaneously injecting the same tumor-bearing animal with a peptide mixture of P3378 DyLight (DL)680 and the P3378R-DL800. Coinjection of P3378-DL680 with excess unlabeled P3378 blocked tumor accumulation of fluorescent signal while excess P3378R control peptide did not confirming the sequence specificity of the tumor accumulation. Finally, ex vivo fluorescence microscopy of these tumors confirmed the presence of P3378-DL680 in the tumor and its colocalization with CLU. These results confirm the tumor targeting specificity of the P3378 CLU-binding peptide and suggest its usefulness for the in vivo monitoring of solid tumors secreting detectable levels of CLU. DA - 2012/01/27 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5c47a73a-9c74-48be-8367-c2697ed9b395 ER - TY - JOUR TI - Chiral modulations and reorientation effects in MnSi thin films DO - 10.1103/PhysRevB.85.094429 AU - Karhu, E. A. AU - Roßler, U. K. AU - Bogdanov, A. N. AU - Kahwaji, S. AU - Kirby, B. J. AU - Fritzsche, H. AU - Robertson, M. D. AU - Majkrzak, C. F. AU - Monchesky, T. L. T2 - Physical Review B : Condensed Matter and Materials Physics VL - 85 IS - 9 SP - 094429-1 EP - 094429-12 AB - We present an experimental and theoretical investigation of the influence of a uniaxial magnetocrystalline anisotropy on the magnetic textures that are formed in a chiral magnetic system. We show that the epitaxially induced tensile stress in MnSi thin films grown on Si(111) creates an easy-plane uniaxial anisotropy. The magnetoelastic shear stress coefficient is derived from SQUID magnetometry measurements in combination with transmission electron microscopy and x-ray diffraction data. Density functional calculations of the magnetoelastic coefficient support the conclusion that the uniaxial anisotropy originates from the magnetoelastic coupling. Theoretical calculations based on a Dzyaloshinskii model that includes an easy-plane anisotropy predict a variety of modulations to the magnetic order that are not observed in bulk MnSi crystals. Evidence for these states is found in the magnetic hysteresis and polarized neutron reflectometry measurements. DA - 2012/03/27 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6ce36bf6-6720-46f4-a24a-3143893b5a87 ER - TY - JOUR TI - Probing the room temperature deuterium absorption kinetics in nanoscale magnesium based hydrogen storage multilayers using neutron reflectometry, X-ray diffraction, and atomic force microscopy DO - 10.1021/jp209296b AU - Kalisvaart, W. P. AU - Luber, E. J. AU - Poirier, E. AU - Harrower, C. T. AU - Teichert, A. AU - Wallacher, D. AU - Grimm, N. AU - Steitz, R. AU - Fritzsche, H. AU - Mitlin, D. T2 - The Journal of Physical Chemistry C VL - 116 IS - 9 SP - 5868 EP - 5880 DA - 2012/02/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2fc7cda8-89e6-4fe8-98bd-8e67c8cab317 ER - TY - CHAP TI - Neutron reflectometry : a unique tool to determine the hydrogen profile in thin films AU - Fritzsche, H. AU - Haagsma, J. AU - Ophus, C. AU - Luber, E. AU - Harrower, T. AU - Mitlin, D. T2 - Role of nuclear based technique in development and characterization of materials for hydrogen storage and fuel cells T2 - IAEA-TECDO; no. 1676 SN - 1011-4289 SN - 978-1-61779-190-1 SP - 79 EP - 84 DA - 2012/02/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cafdf8bb-c6ec-4cdc-a970-7b86ab7b0817 ER - TY - JOUR TI - Optimizing energy productivity of microbial electrochemical cells DO - 10.1016/j.jprocont.2012.04.005 AU - Pinto, R. P. AU - Tartakovsky, B. AU - Srinivasan, B. T2 - Journal of Process Control VL - 22 IS - 6 SP - 1079 EP - 1086 AB - Microbial electrochemical cells, such as microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) are bioreactors that produce energy from organic matter, e.g. wastewater. The goal of this work is to optimize their product generation, either electricity or hydrogen, by selecting optimum operating current, with the influent flow (organic load) being adjusted to guarantee a given treatment capacity. Analysis of a multi-population model of a microbial electrochemical cell reveals that the ratio between different microbial populations in the anodic biofilm is determined by the current. Furthermore, the optimal operating current varies considerably with the internal resistance. DA - 2012/05/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c6da7d16-2b54-4cf4-bd65-dfae2fae9469 ER - TY - JOUR TI - The role of intermetallics on creep behaviour of extruded magnesium alloys DO - 10.1002/9781118359228.ch82 AU - Fletcher, Michelle AU - Bichler, Lukas AU - Sediako, Dimitry T2 - Proceedings of a symposium sponsored by the Magnesium Committee of the Light Metals Division of The Minerals, Metals and Materials Society (TMS) T3 - Magnesium Technology 2012, March 11-15, 2012, Orlando, Florida VL - 2012 SP - 449 EP - 454 KW - Magnesium KW - Neutron Diffraction KW - Creep KW - Microstructure AB - This research examined in-situ creep behavior of three extruded high performance magnesium alloys (AE42, AJ32 and ZE10). Neutron diffraction was used to measure compressive creep behavior at 175°C in the extrusion direction. The AE42 and AJ32 alloys exhibited higher creep strains than the ZE10 alloy. The highest strain was recorded for AE42 (2.4 percent), while ZE10 exhibited greatest creep resistance (0.2 percent strain). Microstructure analysis has shown that the distribution and composition of secondary phases was critical for creep resistance. The aluminum containing alloys had acicular and globular intermetallics, whereas the ZE10 alloy contained fine and irregular intermetallics dispersed along grain boundaries, effectively contributing to pinning of grains under high temperature loads. Significant grain re-crystallization was also observed in the aluminum containing alloys, but was absent in ZE10. DA - 2012/05/12 PY - 2012 PB - Wiley LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 86fe95bb-fd4d-4dbb-a5cb-e5ec7ec5969d ER - TY - JOUR TI - Effect of uniaxial strain on the structural and magnetic phase transitions in BaFe2As2 DO - 10.1103/PhysRevLett.108.087001 AU - Dhital, Chetan AU - Yamani, Z. AU - Tian, Wei AU - Zeretsky, J. AU - Sefat, A. S. AU - Wang, Ziqiang AU - Birgeneau, R. J. AU - Wilson, Stephen D. T2 - Physical Review Letters VL - 108 IS - 8 SP - 087001-1 EP - 087001-4 AB - We report neutron scattering experiments probing the influence of uniaxial strain on both the magnetic and structural order parameters in the parent iron pnictide compound, BaFe₂As₂. Our data show that modest strain fields along the in-plane orthorhombic b axis can affect significant changes in phase behavior simultaneous to the removal of structural twinning effects. As a result, we demonstrate in BaFe₂As₂ samples detwinned via uniaxial strain that the in-plane C₄ symmetry is broken by both the structural lattice distortion and long-range spin ordering at temperatures far above the nominal (strain-free) phase transition temperatures. Surprising changes in the magnetic order parameter of this system under relatively small strain fields also suggest the inherent presence of magnetic domains fluctuating above the strain-free ordering temperature in this material. DA - 2012/02/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ceb8ba87-cf72-41c5-bd77-92873e4ec528 ER - TY - JOUR TI - Phonon density of states and the search for a resonance mode in LaFeAsO0.85F0.15 (Tc = 26 K) DO - 10.1088/1742-6596/340/1/012074 AU - Yamani, Z. AU - Ryan, D. H. AU - Cadogan, J. M. AU - Canepa, F. AU - Palenzona, A. AU - Orecchini, Andrea T2 - Journal of Physics: Conference Series T3 - 5th European Conference on Neutron Scattering (ECNS 2011), July 17-22, 2011, Prague, Czech Republic VL - 340 IS - 1 SP - 012074-1 EP - 012074-6 AB - While the high transition temperatures suggest that the conventional BCS phononmediated mechanism may not provide the main pairing mechanism in the recently discovered RFeAsO1−xFx (1111-type) superconductors, there is, as yet, no consensus, despite extensive experimental and theoretical study. We report here the results of an inelastic neutron scattering investigation of an overdoped polycrystalline sample of LaFeAsO1−xFx with x = 0.15 (Tc = 26 K). Four excitation peaks were observed at 13.6±1.5, 24.2±0.8, 32.2±0.5, and 41.4±1.0 meV. They were identified as phonon modes based on their wavevector and temperature dependence. The peak positions agree well with first-principles calculations of phonon density of states as well as experimental data on both the insulating parent and optimally doped LaFeAsO1−xFx compounds. No evidence for the presence of a resonance mode was found. We found that the phonon density of states of the x = 0.15 sample remains unchanged below Tc and is similar to samples with other fluorine concentrations. This suggests that a standard electron-phonon pairing mechanism cannot explain the high transition temperatures observed in these materials. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cbcc3ce9-dec6-43ab-8f03-77e90fe33b16 ER - TY - JOUR TI - Competing ferri- and antiferromagnetic phases in geometrically frustrated LuFe2O4 DO - 10.1103/PhysRevLett.108.037206 AU - de Groot, J. AU - Marty, K. AU - Lumsden, M. D. AU - Christianson, A. D. AU - Nagler, S. E. AU - Adiga, S. AU - Borghols, W. J. H. AU - Schmalzl, K. AU - Yamani, Z. AU - Bland, S. R. AU - de Souza, R. AU - Staub, U. AU - Schweika, W. AU - Su, Y. AU - Angst, M. T2 - Physical Review Letters VL - 108 IS - 3 SP - 037206-1 EP - 037206-5 AB - We present a detailed study of magnetism in LuFe₂O₄, combining magnetization measurements with neutron and soft x-ray diffraction. The magnetic phase diagram in the vicinity of TN involves a metamagnetic transition separating an antiferro- and a ferrimagnetic phase. For both phases the spin structure is refined by neutron diffraction. Observed diffuse magnetic scattering far above TN is explained in terms of near degeneracy of the magnetic phases. DA - 2012/01/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3a587ddd-b2a3-4418-a3cb-8343647aa8e0 ER - TY - JOUR TI - Coexistence and competition of the short-range incommensurate antiferromagnetic order with superconducting state of BaFe2-xNixAs2 DO - 10.1103/PhysRevLett.108.247002 AU - Luo, Huiqian AU - Zhang, Rui AU - Laver, Mark AU - Yamani, Zahra AU - Wang, Meng AU - Lu, Xingye AU - Wang, Miaoyin AU - Chen, Yanchao AU - Li, Shiliang AU - Chang, Sung AU - Lynn, Jeffrey W. AU - Dai, Pengcheng T2 - Physical Review Letters VL - 108 IS - 24 SP - 247002-1 EP - 247002-5 AB - Superconductivity in the iron pnictides develops near antiferromagnetism, and the antiferromagnetic (AF) phase appears to overlap with the superconducting phase in some materials such as BaFe2-xTxAs2 (where T=Co or Ni). Here we use neutron scattering to demonstrate that genuine long-range AF order and superconductivity do not coexist in BaFe2-xNixAs2 near optimal superconductivity. In addition, we find a first-order-like AF-to-superconductivity phase transition with no evidence for a magnetic quantum critical point. Instead, the data reveal that incommensurate short-range AF order coexists and competes with superconductivity, where the AF spin correlation length is comparable to the superconducting coherence length. DA - 2012/06/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 56aa113d-1450-4a7f-91fd-3206659449b7 ER - TY - JOUR TI - The effect of the B-site cation and oxygen stoichiometry on the local and average crystal and magnetic structures of Sr2Fe1.9M0.1O5+y (M = Mn, Cr, Co; y = 0, 0.5) DO - 10.1039/c2jm30957b AU - Ramezanipour, Farshid AU - Greedan, John E. AU - Cranswick, Lachlan M. D. AU - Garlea, V. Ovidiu AU - Siewenie, Joan AU - King, Graham AU - Llobet, Anna AU - Donaberger, Ronald L. T2 - Journal of Materials Chemistry VL - 22 IS - 19 SP - 9522 EP - 9538 AB - Six compounds with formula Sr₂Fe₁.₉M₀.₁O₅+y (M = Mn, Cr, Co; y = 0, 0.5) were synthesized in air and argon, exhibiting surprisingly different properties depending on the B-cation type in spite of the low (5%) doping level. All argon synthesized phases, y 0, have long range brownmillerite ordering of oxygen vacancies with Icmm symmetry as shown by neutron diffraction (ND). All show long-range G-type antiferromagnetic order with Néel temperatures, TN, from variable temperature ND of 649(3)K, 636(2)K and 668(5)K for Cr, Mn and Co-compounds, respectively, compared with Sr₂Fe₂O₅, TN = 693 K. Competing ferromagnetic interactions may be responsible for the anomalously low value in the M = Mn case. The air synthesized phases with y ~ 0.5 show surprising variation with M as investigated by X-ray, TOF and constant wavelength neutron diffractions. The M = Co compound is isostructural with Sr₄Fe₄O₁₁ (Sr₂Fe₂O₅.₅), Cmmm, while the M = Cr phase is cubic, Pm-3m, and that for M = Mn appears to be cubic but the reflections are systematically broadened in a manner which suggests a local Cmmm structure. NPDF studies show that the local structure of the Cr phase is better described in terms of a Cmmm ordering of oxygen vacancies with Fe–O coordination numbers of five and six. The M = Co material shows C-type antiferromagnetic long-range magnetic order at 4 K as found for Sr₄Fe₄O₁₁. TN 230 K is inferred from a ZFC-FC magnetic susceptibility divergence compared with TN = 232 K for un-doped Sr4Fe4O11. The M = Cr and Mn compounds show no long-range magnetic ordering down to 4 K, but the divergence of ZFC and FC susceptibility data indicative of spin glass-like transitions occur at ~60 K and ~45 K for Cr and Mn, respectively. ND shows both diffuse and sharp Bragg magnetic reflections at positions consistent with a Cmmm cell for the M = Mn phase. For the M = Cr material, a very weak magnetic Bragg peak indexed as (1/2 1/2 1/2), consistent with a G-type AF order, is found at 4 K. These results rule out a spin glass-like ground state for both materials. DA - 2012/03/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8fbf8ce3-57f3-45d4-9f39-1f38f2e8053e ER - TY - JOUR TI - Zn-induced spin dynamics in overdoped La2−xSrxCu1−yZnyO4 DO - 10.1103/PhysRevB.85.014507 AU - Wilson, Stephen D. AU - Yamani, Z. AU - Dhital, Chetan AU - Freelon, B. AU - Freeman, P. G. AU - Fernandez-Baca, J. A. AU - Yamada, K. AU - Wakimoto, S. AU - Buyers, W. J. L. AU - Birgeneau, R. J. T2 - Physical Review B VL - 85 IS - 1 SP - 014507-1 EP - 014507-9 AB - Spin fluctuations and the local spin susceptibility in isovalently Zn-substituted La2−xSrxCu1−yZnyO4 (x=0.25, y≈0.01) are measured via inelastic neutron-scattering techniques. As Zn2+ is substituted onto the Cu2+-sites, an anomalous enhancement of the local spin susceptibility χ′′(ω) appears due to the emergence of a commensurate antiferromagnetic excitation centered at wave vector Q =(π,π,0) that coexists with the known incommensurate spin-density wave excitations at QHK=(π±δ,π),(π,π±δ). Our results support a picture of Zn-induced antiferromagnetic (AF) fluctuations appearing through a local staggered polarization of Cu2+ spins, and the simultaneous suppression of Tc as AF fluctuations are slowed in proximity to Zn impurities suggests the continued importance of high-energy AF fluctuations at the far overdoped edge of superconductivity in the cuprates. DA - 2012/01/17 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3554b1db-e7a9-43b0-96e3-866e294db01f ER - TY - JOUR TI - Neutron scattering from the static and dynamic lattice of SrCu2(BO3)2 in its Shastry-Sutherland DO - 10.1103/PhysRevB.85.134104 AU - Haravifard, S. AU - Gaulin, B. D. AU - Yamani, Z. AU - Dunsiger, S. R. AU - Dabkowska, H. A. T2 - Physical Review B VL - 85 IS - 13 SP - 134104-1 EP - 134104-7 AB - Elastic and inelastic neutron scattering results show that SrCu₂(BO₃)₂ enters its low-temperature singlet ground state below 10 K without an obvious accompanying structural phase transition, despite suggestions emanating from earlier heat capacity measurements. However, evidence for significant spin-phonon coupling is found in the energy widths, and the corresponding lifetimes, of transverse acoustic phonons propagating in the (H00) direction of the Shastry-Sutherland, tetragonal basal plane. Transverse acoustic phonons with energies comparable to and higher than the onset of the two-triplet continuum show substantially increased lifetimes on entering the singlet ground state below ∼10 K. This is qualitatively consistent with the removal of a decay channel for the phonons due to the gapping of the spin excitation spectrum in SrCu₂(BO₃)₂ at low temperatures. DA - 2012/04/12 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b476f0e0-4c87-4779-a3f2-775e9c101150 ER - TY - JOUR TI - Co-existence of gel and fluid lipid domains in single-component phospholipid membranes DO - 10.1039/C2SM07158D AU - Armstrong, C. L. AU - Barrett, M. A. AU - Toppozini, L. AU - Kucerka, N. AU - Yamani, Z. AU - Katsaras, J. AU - Fragneto, G. AU - Rheinstädter, M. C. T2 - Soft Matter VL - 8 IS - 17 SP - 4687 EP - 4694 AB - Lateral nanostructures in membranes, so-called rafts, are believed to strongly influence membrane properties and functions. The experimental observation of rafts has proven difficult as they are thought to be dynamic structures that likely fluctuate on nano- to microsecond time scales. Using neutron diffraction we present direct experimental evidence for the co-existence of gel and fluid lipid domains in a single-component phospholipid membrane made of DPPC as it undergoes its main phase transition. The coherence length of the neutron beam sets a lower limit for the size of structures that can be observed. Neutron coherence lengths between 30 and 242 Å used in this study were obtained by varying the incident neutron energy and the resolution of the neutron spectrometer. We observe Bragg peaks corresponding to co-existing nanometer sized structures, both in out-of-plane and in-plane scans, by tuning the neutron coherence length. During the main phase transition, instead of a continuous transition that shows a pseudo-critical behavior, we observe the co-existence of gel and fluid domains. DA - 2012/03/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 992a10cd-4111-4595-b1ec-8a52547fa93a ER - TY - RPRT TI - Global ice impact forces on the CCGS Amundsen, Beaufort Sea DO - 10.4224/20133409 AU - Johnston, Michelle T2 - Technical Report KW - Ice Impact KW - CCGS Amundsen KW - Beaufort Sea AB - The global ship impact forces on the CCGS Amundsen are quantified here for 44 impacts with multi-year ice floes in the Beaufort Sea. Global impact forces were derived from an inertial measurement system called MOTAN. In general, global forces of up to 9.0 MN were measured for maximum impact speed from 3.1 to 10.2 kt. Most of the impacts were conducted with two floes of known thickness and strength. Only two floes were sampled during the two-week program, but they characterized a wide spectrum of multi-year ice. Floe B1S1 was the thinner of the two floes (7.2 m), quite warm, saline and relatively weak (the depth-averaged borehole strength of the two test holes was 7.3 MPa and 4.5 MPa). Floe B1S2 was thicker (8.0 m), colder, less saline and stronger (the depth-averaged borehole strength of the uppermost 7 m of ice was 22.0 MPa). As anticipated, global impact forces and ship accelerations were higher during collisions with the thicker, stronger floe than the weaker floe, for comparable ship speeds. The highest surge acceleration (1.03 m/s²) occurred during the final ram with Floe B1S2 which was conducted at a maximum impact speed of 6.7 kt. That collision generated the highest global impact force of the program: 9.0 MN. The highest heave acceleration (0.84 m/s²) and sway acceleration (0.46 m/s²) occurred during rams with Floe B1S1, while transiting to a natural harbour within the floe. Global forces from 18 impacts with isolated multi-year floes floating in open pack ice were comparable to many of the rams with Floe B1S1, for a given impact speed. Comparison of the Commanding Officer’s expected ice severity for the 18 impacts indicated that even experienced personnel can have difficulty ascertaining the competency of multi-year ice. Impact forces and accelerations measured by MOTAN on the CCGS Amundsen were comparable to MOTAN-derived measurements on the CCGS Terry Fox from oblique impacts with bergy bits. The maximum heave, surge and sway accelerations on the CCGS Terry Fox were respectively 0.57 m/s², 0.56 m/s² and 1.24 m/s² during the Bergy Bit Trials, with measured global impact forces of up to 10.6 MN. Global impact forces and accelerations on the CCGS Amundsen during this study were not nearly as high as the impact forces measured by other instrumentation systems on ships operating more aggressively in Beaufort Sea multi-year ice. DA - 2012/04/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bf0fe142-8f3b-4412-8ed2-68fbf9677ccf ER - TY - RPRT TI - Monitoring global ice impact forces on the CCGS Louis S. St-Laurent : interim report DO - 10.4224/20133410 AU - Johnston, Michelle T2 - Technical Report KW - Interim Report KW - Monitoring KW - Ice Impact Forces AB - The global ship impact forces on the CCGS Amundsen are quantified here for 44 impacts with multi-year ice floes in the Beaufort Sea. Global impact forces were derived from an inertial measurement system called MOTAN. In general, global forces of up to 9.0 MN were measured for maximum impact speed from 3.1 to 10.2 kt. Most of the impacts were conducted with two floes of known thickness and strength. Only two floes were sampled during the two-week program, but they characterized a wide spectrum of multi-year ice. Floe B1S1 was the thinner of the two floes (7.2 m), quite warm, saline and relatively weak (the depth-averaged borehole strength of the two test holes was 7.3 MPa and 4.5 MPa). Floe B1S2 was thicker (8.0 m), colder, less saline and stronger (the depth-averaged borehole strength of the uppermost 7 m of ice was 22.0 MPa). As anticipated, global impact forces and ship accelerations were higher during collisions with the thicker, stronger floe than the weaker floe, for comparable ship speeds. The highest surge acceleration (1.03 m/s²) occurred during the final ram with Floe B1S2 which was conducted at a maximum impact speed of 6.7 kt. That collision generated the highest global impact force of the program: 9.0 MN. The highest heave acceleration (0.84 m/s²) and sway acceleration (0.46 m/s²) occurred during rams with Floe B1S1, while transiting to a natural harbour within the floe. Global forces from 18 impacts with isolated multi-year floes floating in open pack ice were comparable to many of the rams with Floe B1S1, for a given impact speed. Comparison of the Commanding Officer’s expected ice severity for the 18 impacts indicated that even experienced personnel can have difficulty ascertaining the competency of multi-year ice. Impact forces and accelerations measured by MOTAN on the CCGS Amundsen were comparable to MOTAN-derived measurements on the CCGS Terry Fox from oblique impacts with bergy bits. The maximum heave, surge and sway accelerations on the CCGS Terry Fox were respectively 0.57 m/s², 0.56 m/s² and 1.24 m/s² during the Bergy Bit Trials, with measured global impact forces of up to 10.6 MN. Global impact forces and accelerations on the CCGS Amundsen during this study were not nearly as high as the impact forces measured by other instrumentation systems on ships operating more aggressively in Beaufort Sea multi-year ice. DA - 2012/04/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0241c2c1-019c-4f4c-b319-21c9989dfa4c ER - TY - JOUR TI - Modelling the impact of variations in electrode manufacturing on lithium-ion battery modules DO - 10.1016/j.jpowsour.2012.03.065 AU - Kenney, Ben AU - Darcovich, Ken AU - MacNeil, Dean D. AU - Davidson, Isobel J. T2 - Journal of Power Sources VL - 213 SP - 391 EP - 401 KW - Lithium-ion battery KW - Electrode variability KW - Degradation KW - Battery modules KW - Battery packs AB - The performance of a lithium-ion battery is closely related to its manufacturing and can be impacted by variability in the electrodes. Typically, manufacturers must set aside cells which are deemed to be of insufficient quality, thus contributing to the cost of manufacturing high quality cells. The performance of a lithium-ion battery module, that is, a string of cells configured in series, depends on the performance of the weakest cell. In this work, the single particle model was adapted to simulate the coupled behaviour of an arbitrary number of cells configured in series. The impact of slight variations in the manufacturing of electrodes was then investigated with a goal of linking electrode properties such as variations in thickness, electrode density and active material weight fraction with the performance of battery modules made from these cells. Results indicate that the initial capacity, the rate of capacity fade and other important aspects such as the distribution of state-of-charge from one cell to another depends on the extent of variability in the manufacturing of the electrodes. In this work, the variation in the performance of the module has been quantified as a function of manufacturing variation at the electrode level. DA - 2012/04/13 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b0f9aed6-22fb-483b-b3d7-d99c692f1988 ER - TY - JOUR TI - Identification and characterization of antifungal compounds using a Saccharomyces cerevisiae reporter bioassay DO - 10.1371/journal.pone.0036021 AU - Tebbets, Brad AU - Stewart, Douglas AU - Lawry, Stephanie AU - Nett, Jeniel AU - Nantel, Andre AU - Andes, David AU - Klein, Bruce S. T2 - PLoS ONE SN - 1932-6203 VL - 7 IS - 5 SP - e36021-1 EP - e36021-11 KW - amphotericin B KW - antifungal agent KW - cortisone KW - fluconazole KW - fludioxonil KW - antifungal agent KW - protein histidine kinase KW - protein kinase KW - antifungal activity KW - Aspergillus fumigatus KW - bioassay KW - biofilm KW - Candida albicans KW - candidiasis KW - colony forming unit KW - Cryptococcus KW - disk diffusion KW - down regulation KW - drug potency KW - drug screening KW - drug structure KW - drug targeting KW - fungal strain KW - fungus growth KW - genetic transcription KW - high throughput screening KW - Magnaporthe grisea KW - microarray analysis KW - minimum inhibitory concentration KW - oxidative stress KW - protein expression KW - rat KW - Rhizopus oryzae KW - Saccharomyces cerevisiae KW - single drug dose KW - upregulation KW - antifungal resistance KW - DNA damage KW - DNA microarray KW - DNA repair KW - drug effect KW - drug potentiation KW - reporter gene KW - Candida KW - Mammalia KW - Biological Assay KW - Drug Evaluation, Preclinical KW - Drug Resistance, Fungal KW - Drug Synergism KW - Microbial Sensitivity Tests KW - Oligonucleotide Array Sequence Analysis AB - New antifungal drugs are urgently needed due to the currently limited selection, the emergence of drug resistance, and the toxicity of several commonly used drugs. To identify drug leads, we screened small molecules using a Saccharomyces cerevisiae reporter bioassay in which S. cerevisiae heterologously expresses Hik1, a group III hybrid histidine kinase (HHK) from Magnaporthe grisea. Group III HHKs are integral in fungal cell physiology, and highly conserved throughout this kingdom; they are absent in mammals, making them an attractive drug target. Our screen identified compounds 13 and 33, which showed robust activity against numerous fungal genera including Candida spp., Cryptococcus spp. and molds such as Aspergillus fumigatus and Rhizopus oryzae. Drug-resistant Candida albicans from patients were also highly susceptible to compounds 13 and 33. While the compounds do not act directly on HHKs, microarray analysis showed that compound 13 induced transcripts associated with oxidative stress, and compound 33, transcripts linked with heavy metal stress. Both compounds were highly active against C. albicans biofilm, in vitro and in vivo, and exerted synergy with fluconazole, which was inactive alone. Thus, we identified potent, broad-spectrum antifungal drug leads from a small molecule screen using a high-throughput, S. cerevisiae reporter bioassay. DA - 2012/05/04 PY - 2012 PB - PLOS LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5ea6d4bb-d768-4a36-8250-e5949a53d2ec ER - TY - JOUR TI - Driver mutations in histone H3.3 and chromatin DO - 10.1038/nature10833 AU - Schwartzentruber, Jeremy AU - Korshunov, Andrey AU - Liu, Xiao-Yang AU - Jones, David T. W. AU - Pfaff, Elke AU - Jacob, Karine AU - Sturm, Dominik AU - Fontebasso, Adam M. AU - Khuong Quang, Dong-Anh AU - Tönjes, Martje AU - Hovestadt, Volker AU - Albrecht, Steffen AU - Kool, Marcel AU - Nantel, Andre AU - Konermann, Carolin AU - Lindroth, Anders AU - Jäger, Natalie AU - Rausch, Tobias AU - Ryzhova, Marina AU - Korbel, Jan O. AU - Hielscher, Thomas AU - Hauser, Peter AU - Garami, Miklos AU - Klekner, Almos AU - Bognar, Laszlo AU - Ebinger, Martin AU - Schuhmann, Martin U. AU - Scheurlen, Wolfram AU - Pekrun, Arnulf AU - Frühwald, Michael C. AU - Roggendorf, Wolfgang AU - Kramm, Christoph AU - Dürken, Matthias AU - Atkinson, Jeffrey AU - Lepage, Pierre AU - Montpetit, Alexandre AU - Zakrzewska, Magdalena AU - Zakrzewski, Krzystof AU - Liberski, Pawel P. AU - Dong, Zhifeng AU - Siegel, Peter AU - Kulozik, Andreas E. AU - Zapatka, Marc AU - Guha, Abhijit AU - Malkin, David AU - Felsberg, Jörg AU - Reifenberger, Guido AU - von Deimling, Andreas AU - Ichimura, Koichi AU - Collins, V. Peter AU - Witt, Hendrik AU - Milde, Till AU - Witt, Olaf AU - Zhang, Cindy AU - Castelo-Branco, Pedro AU - Lichter, Peter AU - Faury, Damien AU - Tabori, Uri AU - Plass, Christoph AU - Majewski, Jacek AU - Pfister, Stefan M. AU - Jabado, Nada T2 - Nature VL - 482 IS - 7384 SP - 226 EP - 231 AB - Glioblastoma multiforme (GBM) is a lethal brain tumour in adults and children. However, DNA copy number and gene expression signatures indicate differences between adult and paediatric cases. To explore the genetic events underlying this distinction, we sequenced the exomes of 48 paediatric GBM samples. Somatic mutations in the H3.3-ATRX-DAXX chromatin remodelling pathway were identified in 44% of tumours (21/48). Recurrent mutations in H3F3A, which encodes the replication-independent histone 3 variant H3.3, were observed in 31% of tumours, and led to amino acid substitutions at two critical positions within the histone tail (K27M, G34R/G34V) involved in key regulatory post-translational modifications. Mutations in ATRX (α-thalassaemia/mental retardation syndrome X-linked) and DAXX (death-domain associated protein), encoding two subunits of a chromatin remodelling complex required for H3.3 incorporation at pericentric heterochromatin and telomeres, were identified in 31% of samples overall, and in 100% of tumours harbouring a G34R or G34V H3.3 mutation. Somatic TP53 mutations were identified in 54% of all cases, and in 86% of samples with H3F3A and/or ATRX mutations. Screening of a large cohort of gliomas of various grades and histologies (n = 784) showed H3F3A mutations to be specific to GBM and highly prevalent in children and young adults. Furthermore, the presence of H3F3A/ATRX-DAXX/TP53 mutations was strongly associated with alternative lengthening of telomeres and specific gene expression profiles. This is, to our knowledge, the first report to highlight recurrent mutations in a regulatory histone in humans, and our data suggest that defects of the chromatin architecture underlie paediatric and young adult GBM pathogenesis. DA - 2012/01/29 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f253b4af-2e93-4531-8d22-a44008e1428f ER - TY - JOUR TI - The functions of Mediator in Candida albicans support a role in shaping species-specific gene expression DO - 10.1371/journal.pgen.1002613 AU - Uwamahoro, Nathalie AU - Qu, Yue AU - Jelicic, Branka AU - Lo, Tricia L. AU - Beaurepaire, Cecile AU - Quenault, Tara AU - Boag, Peter R. AU - Ramm, Georg AU - Callaghan, Judy AU - Beilharz, Traude H. AU - Nantel, André AU - Peleg, Anton Y. AU - Traven, Ana T2 - PLoS Genetics VL - 8 IS - 4 SP - e1002613 SP - 1 EP - 18 DA - 2012/04/05 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8df2cc9e-710a-474c-96de-66c1ec050fb5 ER - TY - JOUR TI - Pho85, Pcl1, and Hms1 signaling governs Candida albicans morphogenesis induced by high temperature or Hsp90 compromise DO - 10.1016/j.cub.2012.01.062 AU - Shapiro, Rebecca S. AU - Sellam, Adnane AU - Tebbji, Faiza AU - Whiteway, Malcolm AU - Nantel, Andre AU - Cowen, Leah E. T2 - Current Biology VL - 22 IS - 6 SP - 461 EP - 470 AB - Background Temperature exerts powerful control over development and virulence of diverse pathogens. In the leading human fungal pathogen, Candida albicans, temperature governs morphogenesis, a key virulence trait. Many cues that induce the yeast to filament transition are contingent on a minimum of 37°C, whereas further elevation to 39°C serves as an independent inducer. The molecular chaperone Hsp90 is a key regulator of C. albicans temperature-dependent morphogenesis. Compromise of Hsp90 function genetically, pharmacologically, or by elevated temperature induces filamentation in a manner that depends on protein kinase A signaling but is independent of the terminal transcription factor, Efg1. Results Here, we establish that despite morphological and regulatory differences, inhibition of Hsp90 induces a transcriptional profile similar to that induced by other filamentation cues and does so independently of Efg1. Further, we identify Hms1 as a transcriptional regulator required for morphogenesis induced by elevated temperature or Hsp90 compromise. Hms1 functions downstream of the cyclin Pcl1 and the cyclin-dependent kinase Pho85, both of which are required for temperature-dependent filamentation. Upon Hsp90 inhibition, Hms1 binds to DNA elements involved in filamentous growth, including UME6 and RBT5, and regulates their expression, providing a mechanism through which Pho85, Pcl1, and Hms1 govern morphogenesis. Consistent with the importance of morphogenetic flexibility for virulence, deletion of C. albicans HMS1 attenuates virulence in a metazoan model of infection. Conclusions Thus, we establish a new mechanism through which Hsp90 orchestrates C. albicans morphogenesis, and define novel regulatory circuitry governing a temperature-dependent developmental program, with broad implications for temperature sensing and virulence of microbial pathogens. DA - 2012/02/23 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 27ed7bb0-4018-418e-8596-d724ae6bb53d ER - TY - JOUR TI - Alternaria alternata as a new fungal enzyme system for the release of phenolic acids from wheat and triticale brans DO - 10.1007/s10482-012-9700-8 AU - Xiao, Zhizhuang AU - Bergeron, Hélène AU - Lau, Peter C. K. T2 - Antonie van Leeuwenhoek VL - 101 IS - 4 SP - 837 EP - 844 AB - This study describes the release of antioxidant ferulic acid from wheat and triticale brans by mixtures of extracellular enzymes produced in culture by a strain FC007 of Alternaria alternata, a dark mold originally isolated from Canadian wood log. The genus of the mold was confirmed as Alternaria by 18S ribosomal DNA characterization. Enzyme activities for feruloyl esterase (FAE) and polysaccharide hydrolyzing enzymes were measured, and conditions for release of ferulic acid and reducing sugars from the mentioned brans were evaluated. The highest level of FAE activity (89 ± 7 mU ml -1 fermentation culture) was obtained on the fifth day of fermentation on wheat bran as growth substrate. Depending on biomass and processing condition, up to 91.2 or 72.3% of the ferulic acid was released from wheat bran and triticale bran, respectively, indicating the proficiency of A. alternata extracellular enzymes in plant cell wall deconstruction. The apparent high extraction of ferulic acid from wheat and triticale brans represents a potential advantage of using a whole fungal cell enzyme complement over yields reported previously through an artificial assembly of cloned FAE with a particular xylanase in a cocktail format. DA - 2012/01/28 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 26023c60-765b-4ec1-8844-eb55fd8b107d ER - TY - JOUR TI - Applications of functionalized and nanoparticle-modified nanocrystalline cellulose DO - 10.1016/j.tibtech.2012.02.001 AU - Lam, Edmond AU - Male, Keith B. AU - Chong, Jonathan H. AU - Leung, Alfred C. W. AU - Luong, John H. T. T2 - Trends in Biotechnology VL - 30 IS - 5 SP - 283 EP - 290 AB - Nanocrystalline cellulose (NCC), a rod-shaped nanoscale material with exceptional strength and physicochemical properties, can be prepared from inexpensive renewable biomass. Besides its potential use as a reinforcing agent for industrial biocomposites, pristine NCC exhibits low toxicity and poses no serious environmental concerns, providing impetus for its use in bioapplications. Here, we review recent developments in the use of modified NCC for emerging bioapplications, specifically enzyme immobilization, antimicrobial and medical materials, green catalysis, biosensing and controlled drug delivery. We focus on the modification of NCC with chemical functionalities and inorganic nanoparticles, reviewing practical considerations such as reusability, toxicity and scale-up capability. © 2012. DA - 2012/03/07 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3987a7dd-7c79-4a0b-a2b9-e8fce720f371 ER - TY - JOUR TI - Life at the wedge: the activity and diversity of Arctic ice wedge microbial communities DO - 10.1089/ast.2011.0730 AU - Wilhelm, Roland C. AU - Radtke, Kristin J. AU - Mykytczuk, Nadia C. S. AU - Greer, Charles W. AU - Whyte, Lyle G. T2 - Astrobiology VL - 12 IS - 4 SP - 347 EP - 360 AB - The discovery of polygonal terrain on Mars underlain by ice heightens interest in the possibility that this water-bearing habitat may be, or may have been, a suitable habitat for extant life. The possibility is supported by the recurring detection of terrestrial microorganisms in subsurface ice environments, such as ice wedges found beneath tundra polygon features. A characterization of the microbial community of ice wedges from the high Arctic was performed to determine whether this ice environment can sustain actively respiring microorganisms and to assess the ecology of this extreme niche. We found that ice wedge samples contained a relatively abundant number of culturable cells compared to other ice habitats (?10 5 CFU•mL -1). Respiration assays in which radio-labeled acetate and in situ measurement of CO 2 flux were used suggested low levels of microbial activity, though more sensitive techniques are required to confirm these findings. Based on 16S rRNA gene pyrosequencing, bacterial and archaeal ice wedge communities appeared to reflect surrounding soil communities. Two Pseudomonas sp. were the most abundant taxa in the ice wedge bacterial library (?50%), while taxa related to ammonia-oxidizing Thaumarchaeota occupied 90% of the archaeal library. The tolerance of a variety of isolates to salinity and temperature revealed characteristics of a psychrotolerant, halotolerant community. Our findings support the hypothesis that ice wedges are capable of sustaining a diverse, plausibly active microbial community. As such, ice wedges, compared to other forms of less habitable ground ice, could serve as a reservoir for life on permanently cold, water-scarce, ice-rich extraterrestrial bodies and are therefore of interest to astrobiologists and ecologists alike. © Copyright 2012, Mary Ann Liebert, Inc. DA - 2012/04/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 19d88fd6-4112-4682-ac63-f544114929d4 ER - TY - JOUR TI - Microbial diversity and activity in hypersaline high Arctic spring channels DO - 10.1007/s00792-011-0417-9 AU - Lay, Chih-Ying AU - Mykytczuk, Nadia C. S. AU - Niederberger, Thomas D. AU - Martineau, Christine AU - Greer, Charles W. AU - Whyte, Lyle G. T2 - Extremophiles VL - 16 IS - 2 SP - 177 EP - 191 KW - Cryomicrobiology KW - Arctic spring KW - Methane seep KW - Polar microbial ecology KW - Thaumarchaeota KW - Hypersaline AB - Lost Hammer (LH) spring is a unique hypersaline, subzero, perennial high Arctic spring arising through thick permafrost. In the present study, the microbial and geochemical characteristics of the LH outflow channels, which remain unfrozen at ≥-18°C and are more aerobic/less reducing than the spring source were examined and compared to the previously characterized spring source environment. LH channel sediments contained greater microbial biomass (~100-fold) and greater microbial diversity reflected by the 16S rRNA clone libraries. Phylotypes related to methanogenesis, methanotrophy, sulfur reduction and oxidation were detected in the bacterial clone libraries while the archaeal community was dominated by phylotypes most closely related to THE ammonia-oxidizing Thaumarchaeota. The cumulative percent recovery of ¹⁴C-acetate mineralization in channel sediment microcosms exceeded ~30% and ~10% at 5 and -5°C, respectively, but sharply decreased at -10°C (≤1%). Most bacterial isolates (Marinobacter, Planococcus, and Nesterenkonia spp.) were psychrotrophic, halotolerant, and capable of growth at -5°C. Overall, the hypersaline, subzero LH spring channel has higher microbial diversity and activity than the source, and supports a variety of niches reflecting the more dynamic and heterogeneous channel environment. DA - 2012/01/14 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c9451f13-1b16-4661-9131-d73dfb411e01 ER - TY - JOUR TI - Characterization of welded joints produced by FSW in AA1100-B4C metal matrix composites DO - 10.1179/1362171811Y.0000000066 AU - Guo, J. F. AU - Gougeon, P. AU - Chen, X.-G. T2 - Science and technology of Welding & Joining VL - 17 IS - 2 SP - 85 EP - 91 KW - Friction Stir Welding, Al-B4C Metal Matrix Composite KW - Microstructure KW - Mechanical Properties KW - Ductility KW - Joint Efficiency KW - Grain Structure KW - Fractography AB - The feasibility of friction stir welding for joining AA 1100 based metal matrix composites reinforced with B4C particulate is studied for 16 and 30%B4C volume concentrations. For both composites, friction stir welding has a significant influence on the particle size distribution and the matrix grain size. For the 16% composite, the average particle size decreases after welding by ,20% and the grain size from 15 to 5 mm as measured in the weld nugget. Tensile testing of welded joints showed up to 100% joint efficiency for both annealed AA 1100–16%B4C and AA 1100–30%B4C composite materials. However, if the ultimate tensile strength values of all the studied composites are similar at ,130 MPa, then the weld ductility is higher for the annealed materials. Furthermore, it was observed that varying the welding speed between 100 and 275 mm min21 does not influence the tensile properties and the particle size distribution in the nugget. DA - 2012/02/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 4a2cdc14-f03f-41f7-86df-0a9c624ee15c ER - TY - JOUR TI - SPH model approach used to predict skin inclusions into semisolid metal castings DO - 10.1002/9781118364697.ch26 AU - Pineau, Frédéric AU - D'Amours, Guillaume T2 - CFD Modeling and Simulation in Materials Processing T3 - TMS 2012 Annual Meeting & Exhibition, CFD Modeling and Simulation in Material Processing Symposium, March 11-15, 2012, Orlando, Florida, USA SN - 9781118296158 SN - 111829615X SP - 219 EP - 226 KW - modelling; Smooth Particle Hydrodynamic; semisolid casting AB - Semisolid metal processing of metallic alloys takes advantage of the thixotropic behavior of material with non-dendritic microstructure to produce near-net-shape components with improved mechanical properties. The much higher apparent viscosity of the semisolid billet limits the risk of oxide formed on the free surfaces to become incorporated into the easting during the process. But, the external-skin on the periphery of the billet, which is often partially solidified and contaminated with lubricants, should not be included into the casting as this can be a cause of reject for most structural parts. In this paper, a preliminary model is set-up using the LS-DYNA SPH formulation to follow the paths of the skin. Calculations carried out show that this approach appears to be very promising to predict the paths of contaminated skins into semisolid castings. It can then be utilized to design suitable molds and gating systems. DA - 2012/05/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5708a40f-baa2-43ca-b146-85539cb0f592 ER - TY - JOUR TI - Three dimensional numerical study of the mixing behavior of twin-screw elements DO - 10.3139/217.2450 AU - Ilinca, F. AU - Hétu, J.-F. T2 - International Polymer Processing VL - 27 IS - 1 SP - 111 EP - 120 AB - In this work the numerical modeling of the flow inside co-rotating twin-screw extruders is performed and solutions are analyzed to determine the mixing behavior of two screw elements: conveying and mixing elements. The flow around intermeshing screws is computed using an immersed boundary finite element method capable of dealing with complex moving solid boundaries. The flow is considered isothermal and the material behaves as a generalized non-Newtonian fluid. Because the viscosity depends on the shear rate, solutions will be shown for various rotation velocities of the screw. The 3D solutions are then analyzed in order to determine various parameters characterizing the flow mixing such as the residence time and the linear stretch. Residence time distribution inside the twin-screw extruder is first computed by using a particle tracking algorithm based on a fourth order Runge-Kutta method. A large number of particles are tracked inside the extruder and the resulting particle data is used to determine the distribution of the residence time and of the linear stretch. The spatial distribution of the residence time is also computed by solving a transport equation tracking the injection time of the polymer melt. The methodology shows important differences in the mixing behavior of the screw elements considered. DA - 2012/01/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 366569c5-3b81-4b69-88a8-abcded11798d ER - TY - JOUR TI - Simultaneous analysis of cardiolipin and lipid A from Helicobacter pylori by matrix-assited laser desorption/ionization time-of-flight mass spectrometry DO - 10.1039/C2MB05475B AU - Zhou, Ping AU - Hu, Rui AU - Chandan, Vandana AU - KuoLee, Rhonda AU - Liu, Xin AU - Chen, Wangxue AU - Liu, Bifeng AU - Altman, Eleonora AU - Li, Jianjun T2 - Molecular BioSystems VL - 8 IS - 3 SP - 720 EP - 725 AB - Cardiolipin (CL) is an anionic tetraacylphospholipid found in mammalian tissues, inner membrane of mitochondria and in the cytoplasmic membrane of Gram-positive and -negative bacteria. Lipid A is the principal structural component responsible for the range of biological activities of lipopolysaccharides. Here we report a MALDI-MS-based method for the sensitive simultaneous analysis of CL and lipid A from Helicobacter pylori cells. The sensitivity was demonstrated by the analysis of CL and lipid A from a single bacterial colony of in vitro grown H. pylori strain NCTC 11637 (ATCC 43504). We then characterized the CL and lipid A structures in H. pylori cells grown under three different conditions, on agar-horse blood plates, in liquid culture and ex vivo. The results revealed the presence of high amounts of myristic (C14:0) and 19-carbon cyclopropane (C19:0cyc) fatty acids. Alterations in CL structure were observed in H. pylori cells cultivated on plates as compared with the bacteria grown in broth culture. Furthermore, significant changes in lipid A acylation pattern were detected in H. pylori cells during formation of coccoids. In contrast, structural analysis of CL from ex vivo H. pylori cells recovered from the stomachs of infected Mongolian gerbils demonstrated only minor changes in acyl chain combination. This is the first report of simultaneous analysis of CL and lipid A from ex vivo cells of H. pylori. DA - 2012/01/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bf642fc2-a7a0-4a33-adaa-031df8b73b1f ER - TY - JOUR TI - Colloidal clay gelation: relevance to current oil sands operations DO - 10.1080/10916466.2010.495959 AU - Mercier, P.H.J. AU - Ng, S. AU - Moran, K. AU - Sparks, B.D. AU - Kingston, D. AU - Kotlyar, L.S. AU - Kung, J. AU - Woods, J. AU - Patarachao, B. AU - McCracken, T. T2 - Petroleum Science and Technology VL - 30 IS - 9 SP - 915 EP - 923 KW - bitumen recovery KW - gelation KW - oil sands KW - slime coatings KW - sludging KW - tailings KW - ultrafines AB - Ultrafines are predominantly delaminated colloidal clays with dimensions <0.9um that exist naturally in oil sands and are released during conditioning of surface-mined ores. Critical concentrations of these ultrafines and the cations present in process water are capable of forming flocculated structures with a very high water holding capacity. During primary separation of bitumen these ultrafines are detrimental to recovery as a result of increased slurry viscosity as well as through slime coating of released bitumen. Disposition into tailings ponds eventually produces mature fine tailings (MFT) as a result of thixotropic gel formation that entraps coarser solids. The ultrafines concentration of ~3 wt% observed in MFT coincides with the critical gelation concentration determined for suspensions of ultrafines in salt solutions with cationic concentration representative of that in pond water. This observation accounts for 100% of the water holding capacity of MFT and also explains why virtually no water is released once an MFT gel state has been formed. Here, we review earlier research in this area and identify the harmful effects of ultrafines in some current problematic ores. DA - 2012/03/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2115f38d-0ef0-4380-8468-bfaca769a9e7 ER - TY - JOUR TI - Rapid identification of triacylglycerol-estolides in plant and fungal oils DO - 10.1016/j.indcrop.2011.10.026 AU - Zhang, Haixia AU - Olson, Douglas J. H. AU - Van, Dang AU - Purves, Randy W. AU - Smith, Mark A. T2 - Industrial Crops and Products VL - 37 IS - 1 SP - 186 EP - 194 KW - estolide KW - Lesquerella fendleri KW - Lesquerella lyrata KW - ergot (Claviceps purpurea) KW - seed oil KW - hydroxy fatty acids AB - Triacylglycerol-estolides are components of the storage oil of certain plant and fungal species and are generally associated with the presence of fatty acids containing hydroxyl groups. These unusual acyl-glycerols can easily go undetected when oils are analysed by techniques such as gas chromatography of fatty acid methyl esters, or thin layer chromatography. We describe the detection of TAG-estolides in intact seeds of Lesquerella lyrata and whole sclerotia of the ergot fungus Claviceps purpurea using 1H MAS-NMR for non destructive analysis. We also conducted analysis of small amounts of oil by MALDI-TOF MS to clearly show the presence of TAG-estolides and to rapidly characterize their acyl composition. The matrix used in this work was 2,4,6-trihydroxyacetophenone (THAP) made up in sodium chloride-saturated solvent. We were able to confirm the presence of TAG-estolides with no free hydroxyl groups in the fungal oil, and TAG-estolides with free hydroxyl groups in the oil of Lesquerella lyrata. The development of a technique for the rapid identification of TAG-estolides in oil samples will simplify the detection of these novel lipids in plant and fungal species. DA - 2012/01/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7851e344-6ee8-4c3a-ad27-de43a7edf577 ER - TY - JOUR TI - The hexanoyl-CoA precursor for cannabinoid biosynthesis is formed by an acyl-activating enzyme in Cannabis sativa trichomes DO - 10.1111/j.1365-313X.2012.04949.x AU - Stout, Jake M. AU - Boubakir, Zakia AU - Ambrose, Stephen J. AU - Purves, Randy W. AU - Page, Jonathan E. T2 - The Plant Journal KW - Cannabis sativa KW - marijuana KW - cannabinoid KW - acyl-CoA KW - acyl-activating enzyme KW - hexanoate AB - The psychoactive and analgesic cannabinoids (e.g. Δ9-tetrahydrocannabinol, THC) in Cannabis sativa are formed from the short-chain fatty acyl-CoA precursor hexanoyl-CoA. Cannabinoids are synthesized in glandular trichomes present mainly on female flowers. We quantified hexanoyl-CoA using LC-MS/MS and found levels of 15.5 pmol g−1 fresh weight in female hemp flowers with lower amounts in leaves, stems and roots. This pattern parallels the accumulation of the end-product cannabinoid, cannabidiolic acid (CBDA). To search for the acyl-activating enzyme (AAE) that synthesizes hexanoyl-CoA from hexanoate, we analyzed the transcriptome of isolated glandular trichomes. We identified 11 unigenes encoding putative AAEs, including CsAAE1 which shows high-transcript abundance in glandular trichomes. In vitro assays show that recombinant CsAAE1 activates hexanoate and other short- and medium-chain fatty acids. This activity and the trichome-specific expression of CsAAE1 suggests that it is the hexanoyl-CoA synthetase that supplies the cannabinoid pathway. CsAAE3 encodes a peroxisomal enzyme that activates a variety of fatty acid substrates including hexanoate. Although phylogenetic analysis shows that CsAAE1 groups with peroxisomal AAEs, it lacks a peroxisome targeting sequence 1 (PTS1) and localizes to the cytoplasm. We suggest that CsAAE1 may have been recruited to the cannabinoid pathway through the loss of its PTS1, thereby redirecting it to the cytoplasm. To probe the origin of hexanoate, we analyzed the trichome EST dataset for enzymes of fatty acid metabolism. The high abundance of transcripts encoding desaturases and a lipoxygenase suggests that hexanoate may be formed through a pathway involving the oxygenation and breakdown of unsaturated fatty acids. DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e17e227c-7a46-4771-a096-3c3a11e764af ER - TY - JOUR TI - Triacylglycerol synthesis by PDAT1 in the absence of DGAT1 activity is dependent on re-acylation of LPC by LPCAT2 DO - 10.1186/1471-2229-12-4 AU - Xu, Jingyu AU - Carlsson, Anders S. AU - Francis, Tammy AU - Zhjang, Meng AU - Hoffmann, Travis AU - Giblin, Michael E. AU - Taylor, David C. T2 - BMC Plant Biology VL - 12 IS - 4 KW - dgat1 mutant AS11 KW - LPCAT1 KW - LPCAT2 KW - PDAT1 KW - oil biosynthesis AB - Background: The Arabidopsis thaliana dgat1 mutant, AS11, has an oil content which is decreased by 30%, and a strongly increased ratio of 18:3/20:1, compared to wild type. Despite lacking a functional DGAT1, AS11 still manages to make 70% of WT seed oil levels. Recently, it was demonstrated that in the absence of DGAT1, PDAT1 was essential for normal seed development, and is a dominant determinant in Arabidopsis TAG biosynthesis. Methods: Biochemical, metabolic and gene expression studies combined with genetic crossing of selected Arabidopsis mutants have been carried out to demonstrate the contribution of Arabidopsis PDAT1 and LPCAT2 in the absence of DGAT1 activity. Results: Through microarray and RT-PCR gene expression analyses of AS11 vs. WT mid-developing siliques, we observed consistent trends between the two methods. FAD2 and FAD3 were up-regulated and FAE1 down-regulated, consistent with the AS11 acyl phenotype. PDAT1 expression was up-regulated by ca 65% while PDAT2 expression was up-regulated only 15%, reinforcing the dominant role of PDAT1 in AS11 TAG biosynthesis. The expression of LPCAT2 was up-regulated by 50-75%, while LPCAT1 expression was not significantly affected. In vitro LPCAT activity was enhanced by 75-125% in microsomal protein preparations from mid-developing AS11 seed vs WT. Co-incident homozygous knockout lines of dgat1/lpcat2 exhibited severe penalties on TAG biosynthesis, delayed plant development and seed set, even with a functional PDAT1; the double mutant dgat1/lpcat1 showed only marginally lower oil content than AS11. Conclusions: Collectively, the data strongly support that in AS11 it is LPCAT2 up-regulation which is primarily responsible for assisting in PDAT1-catalyzed TAG biosynthesis, maintaining a supply of PC as co-substrate to transfer sn-2 moieties to the sn-3 position of the enlarged AS11 DAG pool. DA - 2012/01/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f9adf6ff-41d2-4a46-8ff9-c1b3471a5a75 ER - TY - JOUR TI - Overexpression of Nelumbo nucifera metallothioneins 2a and 3 enhances seed germination vigor in Arabidopsis DO - 10.1007/s00425-011-1527-4 AU - Zhou, Yuliang AU - Chu, Pu AU - Chen, Huhui AU - Li, Yin AU - Liu, Jun AU - Ding, Yu AU - Tsang, Edward W. T. AU - Jiang, Liwen AU - Wu, Keqiang AU - Huang, Shangzhi T2 - Planta VL - 235 IS - 3 SP - 523 EP - 537 KW - Arabidopsis KW - Metallothionein KW - Oxidative stresses KW - Sacred lotus KW - Salt stress KW - Seed germination vigor AB - Metallothioneins (MTs) are small, cysteine-rich and metal-binding proteins which are involved in metal homeostasis and scavenging of reactive oxygen species. Although plant MTs have been intensively studied, their roles in seeds remain to be clearly established. Here, we report the isolation and characterization of NnMT2a, NnMT2b and NnMT3 from sacred lotus (Nelumbo nucifera Gaertn.) and their roles in seed germination vigor. The transcripts of NnMT2a, NnMT2b and NnMT3 were highly expressed in developing and germinating sacred lotus seeds, and were dramatically up-regulated in response to high salinity, oxidative stresses and heavy metals. Analysis of transformed Arabidopsis protoplasts showed that NnMT2a-YFP and NnMT3-YFP were localized in cytoplasm and nucleoplasm. Transgenic Arabidopsis seeds overexpressing NnMT2a and NnMT3 displayed improved resistance to accelerated aging (AA) treatment, indicating their significant roles in seed germination vigor. These transgenic seeds also exhibited higher superoxide dismutase activity compared to wild-type seeds after AA treatment. In addition, we showed that NnMT2a and NnMT3 conferred improved germination ability to NaCl and methyl viologen on transgenic Arabidopsis seeds. Taken together, these data demonstrate that overexpression of NnMT2a and NnMT3 in Arabidopsis significantly enhances seed germination vigor after AA treatment and under abiotic stresses. DA - 2012/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 443a4ac8-d0bb-4bc1-adfd-dd94417292c2 ER - TY - JOUR TI - Photoluminescence fatigue in three-dimensional silicon/silicon-germanium nanostructures DO - 10.1063/1.3698303 AU - Modi, N. AU - Tsybeskov, L. AU - Baribeau, J.-M. AU - Wu, X. AU - Lockwood, D. J. T2 - Journal of Applied Physics VL - 111 IS - 6 SP - 064318 SP - 064318-1 EP - 064318-3 AB - We find fatigue of low temperature photoluminescence (PL) in Si/SiGe three-dimensional island morphology nanostructures under continuous excitation. Initially, the PL intensity slowly decreases by less than 15%, and after ~10 min it decreases rapidly by more than 80%. After the PL intensity stabilizes, a complete recovery requires heating the sample to nearly room temperature. We propose that accumulation of charge within SiGe islands is responsible for the enhancement of Auger recombination and hence the observed PL fatigue. DA - 2012/03/26 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bd979c04-4889-4bf4-a095-1179278424e6 ER - TY - JOUR TI - Chiral separation with molecularly imprinted polysulfone-aldehyde derivatized nanofiber membranes DO - 10.1016/j.memsci.2012.01.033 AU - Sueyoshi, Yuuki AU - Utsunomiya, Akira AU - Yoshikawa, Masakazu AU - Robertson, Gilles P. AU - Guiver, Michael D. T2 - Journal of Membrane Science VL - 401-402 IS - 15 May 2012 SP - 89 EP - 96 KW - Electrospray deposition KW - Chiral separation KW - Membrane KW - Molecular imprinting KW - Molecularly imprinted nanofiber membrane KW - Nanofiber fabric KW - Optical resolution AB - Molecularly imprinted membranes (MIPMs) and molecularly imprinted nanofiber membranes (MINFMs) were prepared from polysulfone with aldehyde (PSf-CHO-05 or PSf-CHO-10) and N- -benzyloxycarbonyl-D-gultamic acid (Z-D-Glu) or N-a-benzyloxycarbonyl-L-glutamic acid (Z-L-Glu) as a print molecule. Those two types of molecularly imprinted membrane, such as MIPMs and MINFMs, incorporated the enantiomer, of which absolute configuration was same as that of the print molecule, in preference to the corresponding antipode. In other words, the membranes imprinted by the D-isomer preferentially adsorbed the D-isomer and vice-versa. Those two types of membrane showed chiral separation ability by membrane transport. Against expectation, transport of the enantiomer less adsorbed in the membrane was selectively transported. The fluxes through the molecularly imprinted nanofiber membranes gave one to two orders of magnitude higher than those of usual molecularly imprinted membranes without depression of permselectivity. The present study demonstrated that molecularly imprinted nanofiber membrane gave high flux without depression of permselectivity. A breakthrough in membrane separation would be realized by adopting molecularly imprinted nanofiber membranes. DA - 2012/02/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b7efc168-7dc6-4e45-a453-fa922aee9161 ER - TY - JOUR TI - Phenyltrimethylammonium Functionalized Polysulfone Anion Exchange Membranes DO - 10.1021/ma202681z AU - Li, Nanwen AU - Zhang, Qiang AU - Wang, Chenyi AU - Lee, Young Moo AU - Guiver, Michael D. T2 - Macromolecules VL - 45 IS - 5 SP - 2411 EP - 2419 AB - Anion exchange membrane (AEM) materials were prepared from commercial polysulfone (PSf) by functionalization with tertiary amines via lithiation chemistry. By optimizing the reaction conditions, a degree of substitution (DS) of 0.81 could be achieved without evident polymer decomposition or cross-linking. The PSf containing pendent bis-(phenyldimethylamine) substituents were then quaternized with CH3I and ion exchange reaction to provide bis(phenylthrimethylammonium) (PTMA) polymer with hydroxide-conductive properties. Flexible and tough membranes with various ion exchange capacities (IEC)s could be prepared by casting the polymers from DMAc solutions. The ionomeric membranes showed considerably lower water uptake (less than 20%), and thus dimensional swelling in water, compared with many reported AEMs. The hydroxide conductivities of the membranes were above 10 mSécm at room temperature. The unusually low water uptake and good hydroxide conductivity may be attributed to the "side-chain-type" structures of pendent functional groups, which facilitate ion transport. Although the PTMA substituents on the AEM were found to have insufficient long-term stability for alkaline fuel cell application, the investigation gives some insight and directions for polymeric designs by postfunctionalization. DA - 2012/02/28 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 59d57abb-2684-4c75-8ddf-70b4d5cd1b44 ER - TY - JOUR TI - Development of a low-noise wide-band phased-array feed DO - 10.1109/URSIGASS.2011.6123729 AU - Veidt, Bruce AU - Burgess, Tom AU - Messing, Rob AU - Hovey, Gary J. AU - Smegal, Rick J. T2 - General Assembly and Scientific Symposium, 2011 XXXth URSI (URSI GASS, 2011) T3 - Proceedings of the XXXth URSI General Assembly (URSI GASS, 2011), Aug 13-20, 2011, Istanbul, Turkey SN - 978-1-4244-5117-3 SP - 1 EP - 4 KW - Arrays; Bandwidth; Feeds; Radio astronomy; Receivers AB - Low-noise phased-array feeds are a new way to expand the field of view of radio telescopes at centimetre wavelengths. First generation engineering demonstrators of this technology have been constructed and tested by several institutes worldwide. The development of second-generation phased-array feeds is now underway. We describe one effort to design and build an astronomy-capable phased-array feed using techniques to reduce front-end noise and increase system bandwidth. DA - 2012/01/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1d304b65-d5af-4de9-b250-bfa0588e22ca ER - TY - JOUR TI - Elucidation of matrix effects and performance of solid-phase extraction for LC-MS/MS analysis of β-N-methylamino-l-alanine (BMAA) and 2,4-diaminobutyric acid (DAB) neurotoxins in cyanobacteria DO - 10.1039/c2an15887f AU - Li, Aifeng AU - Fan, Hua AU - Ma, Feifei AU - McCarron, Pearse AU - Thomas, Krista AU - Tang, Xianghai AU - Quilliam, Michael A. T2 - Analyst VL - 137 IS - 5 SP - 1210 EP - 1219 AB - A liquid chromatography-mass spectrometry (LC-MS/MS) method using hydrophilic interaction liquid chromatography (HILIC) was developed for the analysis of neurotoxins β-N-methylamino-l-alanine (BMAA) and 2,4-diaminobutyric acid (DAB), using multiple reaction monitoring (MRM) scan mode. Oasis-MCX and Strata-X-C polymeric cation-exchange cartridges were used to clean extracts of cyanobacterial cultures, including two strains of Microcystis aeruginosa and one strain of Nostoc sp. The performance of the solid-phase extraction (SPE) cartridges for BMAA and DAB were evaluated using mixed standards and spiked cyanobacterial extracts, which demonstrated recoveries of BMAA and DAB ranging from 66% to 91%. Matrix effects in LC-MS/MS were evaluated, and while there was no effect on BMAA quantitation, suppression of DAB was found. Full scan (Q1) and enhanced product ion (EPI) monitoring showed that the DAB suppression may be due to closely eluting compounds, including lysine, histidine, arginine and three other compounds with [M + H] +m/z of 88, 164 and 191. The procedures developed allow the sensitive and effective analysis of trace BMAA and DAB levels in cyanobacteria. While DAB was confirmed to be present, no BMAA was found in the cyanobacterial samples tested in the present study. DA - 2012/01/16 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 202ffb70-984d-4f0c-b75d-4949ddccf250 ER - TY - JOUR TI - Changes in enzymatic activity during early development of bay scallops Argopecten irradians and sea scallops Placopecten magellanicus DO - 10.3354/ab00398 AU - Milke, Lisa M. AU - Bricelj, V. Monica AU - Ross, Neil W. T2 - Aquatic Biology VL - 14 IS - 3 SP - 207 EP - 216 KW - digestive enzyme activity KW - scallops KW - Placopecten magellanicus KW - Argopecten ­irradians KW - development AB - Poor growth and survival of scallops is often reported during early developmental stages. Stage- and species-specific dietary requirements have been identified, but the mechanisms responsible for these differences remain largely unknown. Dietary success depends on food biochemical properties, digestive and/or assimilative capacity, as well as the animal's specific nutritional demands, which can vary over development and between species. The present study examines developmental changes in the activities of key digestive enzymes in larval and postlarval bay scallops Argopecten irradians and sea scallops Placopecten magellanicus raised on a mixed algal diet until ~4 to 5 mm in shell height (SH) and sampled at intervals encompassing major transitions in feeding organ development. Colorimetric assays measured general protease, lipase (esterase) and carbohydrase (α-amylase, cellulase and laminarinase) activities. The most pronounced changes in enzymatic activity occurred prior to scallops attaining ~1.2 mm SH in both scallop species. The esterase:protease ratio exhibited similar ontogenetic patterns in both scallop species, decreasing sharply between larval and immediate postlarval stages before increasing to an intermediate level and stabilizing around 1.2 mm SH. In contrast, mean carbohydrase activities measured over the experimental duration differed between species, with bay scallops exhibiting higher specific activities of α-amylase and cellulase but much lower activities of laminarinase than sea scallops. These findings have implications for understanding scallop utilization of the food supply in nature, as well as developing targeted diets that could enhance their growth and survival in culture. DA - 2012/02/08 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f7c66788-a533-45b0-aa8a-ba2543c746a4 ER - TY - JOUR TI - Image formation in CARS and SRS : effect of an inhomogeneous nonresonant background medium DO - 10.1364/OL.37.000473 AU - Popov, K. I. AU - Pegoraro, A. F. AU - Stolow, A. AU - Ramunno, L. T2 - Optics Letters VL - 37 IS - 4 SP - 473 EP - 475 AB - We investigate the role of a spatially inhomogenous nonresonant background medium on several Raman-based imaging modalities. In particular, we consider a small resonant bead submerged in a spatially heterogeneous nonresonant χ(3) background. Using detailed 3D electrodynamic simulations, we compare coherent anti-Stokes Raman scattering (CARS), frequency-modulated CARS, amplitude-modulated stimulated Raman scattering (SRS), and frequency-modulated SRS. We find that only FM-SRS is background-free. DA - 2012/02/06 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 711e4304-29ef-482c-94f8-f124d8282338 ER - TY - JOUR TI - Antiproliferative activity of Saponaria vaccaria constituents and related compounds DO - 10.1016/j.fitote.2011.10.010 AU - Balsevich, J. John AU - Ramirez-Erosa, Irving AU - Hickie, Robert A. AU - Dunlop, Donna M. AU - Bishop, Greg G. AU - Deibert, Leah K. T2 - Fitoterapia VL - 83 IS - 1 SP - 170 EP - 181 KW - Saponaria vaccaria KW - saponins KW - growth inhibition KW - apoptosis KW - cancer KW - MDA-MB-231 KW - PC-3. AB - Total methanolic extracts of Saponaria vaccaria seed derived from several varieties, as well as various purified components obtained through successive chromatographic separations of total extracts were evaluated for their growth inhibitory activity in WiDr (colon), MDA-MB-231 (breast), NCI-417 (lung) and PC-3 (prostate) human cancer cells as well as the non-tumorigenic fibroblast BJ (CRL-2522) cell line using MTT colorimetric assay. Purified bisdesmosidic saponins segetoside H and I were further examined using microscopy and apoptosis assays. Bisdesmosidic saponins exhibited dose-dependent growth inhibitory and selective apoptosis-inducing activity. Growth inhibitory effects were particularly strong in a breast (MDA-MB-231) and a prostate (PC-3) cancer cell line. Total extracts exhibited a different preference being most active against a colon cancer cell line (WiDr). In a comparison of varieties, all of the total seed extracts exhibited similar dose-dependent activities, but with some variation in potency. Monodesmosidic saponins vaccarosides A and B, phenolic vaccarin, and cyclopeptide segetalin A, co-occurring seed substituents, did not exhibit activity. The non-tumorigenic fibroblast cell line BJ (CRL 2522) was growth inhibited but did not undergo apoptosis when treated with bisdesmosidic saponins at low micromolar concentrations. Saponin-rich extracts from Kochia scoparia seed and Chenopodium quinoa were also evaluated alongside Saponaria saponins but did not exhibit activity. Closely related Quillaja saponins exhibited activity but were less potent. DA - 2012/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 2509f5df-7df4-4bcf-8406-983eeb49f9af ER - TY - JOUR TI - Analysis of Phytohormone profiles during male and female cone initiation and early differentiation in long-shoot buds of Lodgepole pine DO - 10.1007/s00344-011-9257-1 AU - Kong, Lisheng AU - von Aderkas, Patrick AU - Zaharia, Irina AU - Abrams, Suzanne R. AU - Lee, Tim AU - Woods, Jack T2 - Journal of Plant Growth Regulation SN - 0721-7595 SN - 1435-8107 VL - 31 IS - 4 SP - 478 EP - 489 KW - cone gender KW - Lodgepole pine KW - long-shoot bud KW - genotype KW - metabolite KW - phytohormone AB - In lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm), cone initiation and gender differentiation are site-specific in long-shoot buds with female cones in the distal portion and male cones in the proximal portion. By using high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) in multiple reaction monitoring (MRM) mode, cytokinins, indole-3-acetic acid (IAA), gibberellins (GAs), abscisic acid (ABA) and their selected metabolites, were investigated in developing long-shoot buds from multiple genotypes. Spatially, higher concentrations of trans-zeatin riboside (t-ZR) and dihydrozeatin (dhZR) existed in the distal parts of long-shoot buds, whereas concentrations of isopentenyl adenosine (iPA), IAA, GA24, ABA, ABA glucose ester (ABA-GE) and phaseic acid (PA) were higher in the proximal parts in all investigated genotypes. In long-shoot buds of genotypes with a history of high female cone yield, concentrations of t-ZR and the ratio of zeatin-type to isopentenyl-type cytokinins were higher in the entire buds, whereas dhZR or IAA was higher either in the distal or in the proximal part respectively. In low female cone yielding genotypes, concentrations of c-ZR, iPA, ABA-GE and PA were higher in both of the parts, whereas ABA was higher mainly in the distal part with higher GA24 in the proximal part. Temporally, concentrations of several hormone-related compounds showed obvious changes in late June and late July, prior to male and female cone bud differentiation. This study reveals that the local hormonal status in a long-shoot bud at specific developmental stages may play an important role in gender determination and cone yield. DA - 2012/01/25 PY - 2012 PB - Springer LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e80eabcd-98d6-4287-bdd8-d87e85481076 ER - TY - JOUR TI - Molecular structure of phospholipase D and regulatory mechanisms of its activity in plant and animal cells DO - 10.1134/S0006297912010014 AU - Kolesnikov, Y. S. AU - Nokhrina, K. P. AU - Kretynin, S. V. AU - Volotovski, I. D. AU - Martinec, J. AU - Romanov, G. A. AU - Kravets, V. S. T2 - Biochemistry (Moscow) VL - 77 IS - 1 SP - 1 EP - 14 KW - phospholipase D KW - domains KW - calcium KW - lipids KW - G-proteins KW - protein kinases KW - protein–protein interactions AB - Phospholipase D (PLD) catalyzes hydrolysis of phospholipids with production of phosphatidic acids, which often act as secondary messengers on transmission of intracellular signals. This review summarizes data of various leading laboratories on specific features of organization and regulation of PLD activity in plant and animal cells. The main structural domains of PLD (C2, PX, PH), the active site, and other functionally important parts of the enzyme are considered. Regulatory mechanisms of PLD activity are characterized in detail. Studies associated with molecular design, analysis, and synthesis of new nontoxic substances capable of inhibiting different PLD isoenzymes in vivo are shown to be promising for biotechnology and medicine. DA - 2012/01/27 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 740b4fe5-17f1-4ef7-a4bf-ad2d609c57c2 ER - TY - JOUR TI - Halogen and hydrogen host-guest bonding in cathrate hydrates AU - Udachin, Konstantin AU - Ripmeester, John T2 - Proceedings of the 7th International Conference on Gas Hydrates (ICGH 2011) T3 - 7th International Conference on Gas Hydrates (ICGH 2011), 17-21 July 2011, Edinburgh, Scotland, United Kingdom KW - clathrate hydrates, crystal structure, chlorine, bromine, pinacolone, tert-butylamine. AB - Clathrate hydrates with low melting points (often below –20°C) are difficult subjects for single crystal data collection. A high level of guest molecule disorder inside the high symmetry cages causes difficulty for structure determination of such crystals as well. Recent advances in single crystal X-ray diffraction have allowed this technique to be used as a valuable tool for the analysis of hydrate structure and composition. With detailed analysis of guest and water molecules disorder, not only the guest positions are clearly defined, but also it becomes possible to find interactions between guest and water molecules. For the first time, single crystal x-ray crystallography is used to detect the presence of guest host hydrogen and halogen bonding in structure I, II and structure H clathrate hydrates. Clathrates studied are the tert- butylamine (tBA) sII clathrate with H2S and Xe help gases, the pinacolone + H2S binary sH clathrate, 1,3-Dioxolane hydrate, chlorine, bromine, and mixed chlorine with bromine hydrates. X-ray structural analysis shows that the tBA nitrogen atom has a distance of 2.64 Å from the closest large cage oxygen atom. This water molecule is pulled inwards toward the tBA guest (cage center) and the structure of the large cage is substantially distorted in comparison to the ideal cage structure. The pinacolone oxygen atom is determined to have a distance of 2.96 Å from the closest large cage oxygen atom. DA - 2012/07/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cc0266b1-ff5f-471b-b94d-69a7e6db0552 ER - TY - JOUR TI - Ship manoeuvring-in-ice modeling software OSIS-IHI AU - Lau, Michael T2 - 21st International Conference on Port and Ocean Engineering under Arctic Condition 2011 (Proceedings) T3 - 21st International Conference on Port and Ocean Engineering under Arctic Conditions (POAC 2011), 10-14 July 2011, Montreal Canada SN - 9781618392251 KW - OSIS-IHI KW - manoeuvring KW - ice load KW - software KW - ship motions AB - Software to model a ship manoeuvring in ice has been developed which will simulate the ice forces on a ship passing through a field of level ice and the resulting motions. OSIS-IHI (Ocean Structure Interaction Simulator – Ice-Hull Interaction) is an integration of two separatelydeveloped components. The first component is a static force solver that uses discrete-time motion data to calculate the resultant ice forces at a given point in time. The second component is an ordinary differential equation solver that produces dynamic motion data given a set of steering methods, such as propeller revolution and rudder angle deflection. It has been verified extensively and used for client consulting work with success. The development and integration of both components is discussed, accompanied by preliminary verifications. DA - 2012/01 PY - 2012 PB - Curran Associates, Incorporated LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9e65fc57-f420-4018-8364-93fee3993425 ER - TY - JOUR TI - Numerical assessment for stationary structure (Kulluk) in moving broken ice AU - Wang, J. AU - Derradji-Aouat, A. T2 - 21st International Conference on Port and Ocean Engineering under Arctic Condition 2011 (Proceedings) T3 - 21st International Conference on Port and Ocean Engineering under Arctic Conditions (POAC 2011), 10-14 July 2011, Montreal Canada SN - 9781618392251 KW - LS-DYNA KW - structure ice interaction KW - managed ice KW - Arbitrary Lagrangian Eulerian method DA - 2012/01 PY - 2012 PB - Curran Associates, Incorporated LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1df13996-d80e-49d3-a9a4-045770f6a98b ER - TY - JOUR TI - Performance measurements of the effect of simulator training on novice operators in simulated ice conditions AU - Power MacDonald, Stephanie AU - MacKinnon, Scott AU - Simões Ré, Antonio AU - Power, Jonathan T2 - 21st International Conference on Port and Ocean Engineering under Arctic Condition 2011 (Proceedings) T3 - 21st International Conference on Port and Ocean Engineering under Arctic Conditions (POAC 2011), 10-14 July 2011, Montreal Canada SN - 9781618392251 SP - 112 KW - simulation training KW - EER (Escape, Evacuation, and Rescue) KW - STCW KW - arctic environment AB - Shipping and offshore sectors are moving operations into the ice-covered waters of the Arctic. As these exploration endeavours evolve, more guidance is needed for equipment, procedures, and training to operate in cold, harsh environments. At present, limited training exists for lifeboat coxswains charged with navigating lifeboats in ice-covered water during emergency evacuation situations. This research study examines the effectiveness of simulator training in comparison with traditional Standard Training, Certification and Watchkeeping (STCW) training for navigating lifeboats in ice fields. These findings will inform manufacturers, trainers and regulators regarding the operational demands and training requirements needed to safely and efficiently perform these tasks. DA - 2012/01 PY - 2012 PB - Curran Associates, Incorporated LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 47029146-9a04-4be0-a3ca-ab7f525ddd99 ER - TY - JOUR TI - Microstructural effects on the mechanical properties of ATI 718Plus® Alloy DO - 10.1007/s11837-012-0242-3 AU - Kearsey, R. M. AU - Tsang, J. AU - Oppenheimer, S. AU - McDevitt, E. T2 - Journal of the Minerals, Metals and Materials Society VL - 64 IS - 2 SP - 241 EP - 251 KW - Superalloys; damage tolerance; FCGR; dwell fatigue; ATI 718Plus Alloy; Waspaloy AB - Four microstructural variants of ATI 718Plus® alloy (718Plus) have been investigated to elucidate the effects of grain size, precipitate size, morphology, and phase fraction (δ and γ′) on mechanical properties such as low cycle fatigue (LCF) life, fatigue crack growth rate (FCGR) properties, and dwell FCGR behavior at both 649°C and 704°C under 100 s dwell and nondwell conditions. Similar tests have also been performed on Waspaloy in two comparative microstructural conditions. LCF test results demonstrate that all four microstructural conditions of 718Plus have superior life compared with Waspaloy under all investigated test conditions. FCGR results show that, at both test temperatures, all microstructural conditions of 718Plus and Waspaloy exhibit identical behavior in the steady-state regime, except that 718Plus exhibits a much higher threshold stress intensity (ΔK TH). However, the dwell FCGR results show that Waspaloy displays better steady-state crack growth resistance under dwell conditions. However, with a thermal exposed precipitate microstructure, 718Plus shows considerable improvement in this response. DA - 2012/02/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 72b31b72-e140-4fdb-8995-05cd2fbf1d5e ER - TY - JOUR TI - Static strength of a composite butt joint configuration with different attachments DO - 10.1016/j.compstruct.2011.12.008 AU - Li, Gang AU - Chen, Ji Hua AU - Yanishevsky, Marko AU - Bellinger, Nicholas C. T2 - Composite Structures VL - 94 IS - 5 SP - 1736 EP - 1744 KW - Bonded-bolted composite joints; Damage; Failure mode; Ultimate strength AB - The static failure behaviour of a composite single-strap joint configuration using three different attachments was studied experimentally. The attachments used were: adhesive bonding; mechanical bolting; and bonded-bolted joining. The dimensions of the composite butt joint used were determined based on actual joint configurations in aircraft structures, such that the test results would be beneficial to both the academic exploration and practical engineering application for advanced composite joint design and analysis. A damage evolution process was presented for the bonded-bolted butt joints based on the observed stress versus displacement curves and associated failure modes from all the related butt joints with the three attachments. An approach was then proposed for estimating the ultimate tensile strength in the bonded-bolted joints. DA - 2012/04/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 982ae4cd-a42a-464d-b82f-891cb411bf39 ER - TY - JOUR TI - How language enables abstraction : a study in computational cultural psychology DO - 10.1007/s12124-011-9165-8 AU - Neuman, Yair AU - Turney, Peter AU - Cohen, Yohai T2 - Integrative Psychological and Behavioral Science VL - 46 IS - 2 SP - 129 EP - 145 KW - thought and language KW - abstraction KW - hypostatic abstraction KW - computational cultural psychology AB - The idea that language mediates our thoughts and enables abstract cognition has been a key idea in socio-cultural psychology. However, it is not clear what mechanisms support this process of abstraction. Peirce argued that one mechanism by which language enables abstract thought is hypostatic abstraction, the process through which a predicate (e.g., dark) turns into an object (e.g., darkness). By using novel computational tools we tested Peirce’s idea. Analysis of the data provides empirical support for Peirce's mechanism and evidence of the way the use of signs enables abstraction. These conclusions are supported by the in-depth analysis of two case studies concerning the abstraction of sweet and dark. The paper concludes by discussing the findings from a broad and integrative theoretical perspective and by pointing to computational cultural psychology as a promising perspective for addressing long-lasting questions of the field. DA - 2012/06/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1844c890-6798-4c19-9cf5-d626b88bc56c ER - TY - JOUR TI - Enhanced photonic crystal cavity-waveguide coupling using local slow-light engineering DO - 10.1364/OL.37.000280 AU - Mnaymneh, K. AU - Frederick, S. AU - Dalacu, D. AU - Lapointe, J. AU - Poole, P. J. AU - Williams, R. L. T2 - OPTICS LETTERS VL - 37 IS - 2 SP - 280 EP - 282 AB - This Letter introduces an enhanced cavity-waveguide coupling architecture based upon slow-light engineering in a two-port photonic crystal system. After analyzing the system transmittance using coupled-mode theory, the system is probed experimentally and shown to have increased transmittance due to the enhanced cavity-waveguide coupling. Such a coupling architecture may facilitate next-generation planar lightwave circuitry such as onchip quantum information processing or high precision light-matter sensing applications. DA - 2012/01/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1c319bc8-0c7c-4187-b1dc-3067183bd975 ER - TY - JOUR TI - Ultrawide-bandwidth, superluminescent light-emitting diodes using InAs quantum dots of tuned height DO - 10.1364/OL.37.001103 AU - Haffouz, S. AU - Barrios, P. J. AU - Normandin, R. AU - Poitras, D. AU - Lu, Z. T2 - OPTICS LETTERS VL - 37 IS - 6 SP - 1103 EP - 1105 AB - An ultrawide-bandwidth, superluminescent light-emitting diode (SLED) utilizing multiple layers of dots of tuned height is reported. Due to thermal effect, the superluminescent phenomenon is observed only under pulse-mode operation. The device exhibits a 3 dB bandwidth of 190 nm with central wavelength of 1020 nm under continuouswave (cw) conditions. The maximum corresponding output power achieved in this device under cw and pulsed operation conditions are 0.54 mW and 17 mW, respectively. DA - 2012/03/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 88778dd3-9c1c-448b-9425-c886829bbf17 ER - TY - JOUR TI - Lipid sensing apolipoprotein A-I for novel high -throughput lipidation assays DO - 10.1016/j.bpj.2011.11.384 AU - Niedziela-Majka, Anita AU - Lad, Latesh AU - Chishom, Jeffrey W. AU - Lagpacan, Leanna AU - Schwartz, Karen AU - Hung, Magdeleine AU - Jin, Debi AU - Fung, Wanchi AU - Brendza, Katherine M. AU - Liu, Xioahong AU - Pagratis, Nikos AU - Sakowicz, Roman T2 - Biophysical Journal VL - 102 IS - Supplement 1 SP - 65a KW - high-throughput KW - lipid sensing KW - apolipoprotein AB - Apolipoprotein A-I (ApoA-I) is the primary protein component of high density lipoproteins (HDL). ApoA-I plays an important role in cholesterol metabolism by mediating the formation of nascent HDL and the efflux of cellular cholesterol from macrophage foam cells in arterial walls. Lipidation of ApoA-I is mediated by the ATP-binding cassette A1 (ABCA1). Insufficient ABCA1 activity my lead to reduced HDL formation, reduced cholesterol efflux and the development of arteriosclerosis. The standard radioactive assay for measuring cholesterol transport to lipid-free ApoA-I has low through-put, poor dynamic range and fails to measure phospholipid transferred with cholesterol. We describe the development of two sensitive, non-radioactive high-throughput assays that report on the lipidation state of ApoA-I and may have applications for studying ABCA1 function and HDL metabolism: a homogenous assay based on the Time Resolved FRET (TR-FRET) and a discontinuous assay that uses the Epic. The TR-FRET assay employs a fluorescent ApoA-I where Cysteine is labeled with the FRET acceptor HiLyte-Fluor-647 and an N-terminal Biotin-AviTag is bound to the streptavidin-Terbium conjugate. When this ApoA-I was incorporated into recombinant HDL, TR-FRET decreased proportionally to the increase in the ratio of lipid to ApoA-I in agreement with the expansion of the surface area of lipids concomitant with the increase in separation of N-terminal and central regions of the protein and demonstrated that the HTRF assay was sensitive to the amount of lipid associated with ApoA-I. The Epic is a label-free platform that allows for the observation of direct biomolecular interactions via a resonant wavelength shift which is proportional to the mass bound to the surface. In the Epic assay, biotinylated ApoA-I was captured on streptavidin-coated sensor. The response was proportional to the amount of lipids associated with ApoA-I indicating that the assay could sense lipidation of ApoA-I. DA - 2012/02/14 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 00510bfa-c65d-4c12-baec-116cbd493e4a ER - TY - CHAP TI - Synthesis of 4-acetamidohexoses in bacteria: structural insights from the bacillosamine and nonulosonic acid pathways AU - Matte, Allan AU - Schoenhofen, Ian C. AU - Sulea, Traian AU - Cygler, Miroslaw AU - Young, N. Martin T2 - Bacterial Glycomics: Current Research, Technology and Applications SN - 978-1-904455-95-0 AB - Many hexose sugars in bacteria undergo a variety of modifications, including oxidation/reduction, amination and acetylation, as part of biosynthesis into their final biologically-active forms. Enzymes that catalyze these reactions normally utilize nucleotide-linked sugar substrates, utilizing the nucleotide as an 'ancient handle' to bind and orient the sugar within the enzymes' active site. We and others have focused efforts on elucidating structure-function relationships for a subset of such biosynthetic enzymes, those associated with the synthesis of trideoxy-diacetamidohexoses, and the nonulsonate sugars subsequently derived from them. With structural information combined with site-directed mutagenesis, enzymatic analysis and molecular modeling, these studies have been essential to understanding the chemistry of how these enzymes bind their substrates and effect catalysis. Enzymes having different folds, such as N-acetyltransferases, can utilize different scaffolds to attain the same 4-acetamido-sugar product. In the case of dehydratases/epimerases and aminotransferases, the enzymes have a conserved structure, but utilize subtle differences within their active site to confer substrate binding and the nature of the final product. These studies depict the structural relationships between these enzymes, while at the same time high-lighting important differences that are beginning to reveal their function at the molecular level. DA - 2012/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8fb62cb0-51b9-429f-bb4b-b1d0ba55f7fd ER - TY - JOUR TI - Increased EID1 nuclear translocation impairs synaptic plasticity and memory function associated with pathogenesis of Alzheimer's disease DO - 10.1016/j.nbd.2011.12.007 AU - Liu, Rugao AU - Lei, Joy X. AU - Luo, Chun AU - Lan, Xun AU - Chi, Liying AU - Deng, Panyue AU - Lei, Saobo AU - Ghribi, Othman AU - Liu, Qing Yan T2 - Neurobiology of Disease VL - 45 IS - 3 SP - 902 EP - 912 KW - EP300 interacting inhibitor of differentiation 1 KW - CBP/p300 KW - histone KW - acetylation KW - Alzheimer's disease AB - Though loss of function in CBP/p300, a family of CREB-binding proteins, has been causally associated with a variety of human neurological disorders, such as Rubinstein–Taybi syndrome, Huntington's disease and drug addiction, the role of EP300 interacting inhibitor of differentiation 1 (EID1), a CBP/p300 inhibitory protein, in modulating neurological functions remains completely unknown. Through the examination of EID1 expression and cellular distribution, we discovered that there is a significant increase of EID1 nuclear translocation in the cortical neurons of Alzheimer's disease (AD) patient brains compared to that of control brains. To study the potential effects of EID1 on neurological functions associated with learning and memory, we generated a transgenic mouse model with a neuron-specific expression of human EID1 gene in the brain. Overexpression of EID1 led to an increase in its nuclear localization in neurons mimicking that seen in human AD brains. The transgenic mice had a disrupted neurofilament organization and increase of astrogliosis in the cortex and hippocampus. Furthermore, we demonstrated that overexpression of EID1 reduced hippocampal long-term potentiation and impaired spatial learning and memory function in the transgenic mice. Our results indicated that the negative effects of extra nuclear EID1 in transgenic mouse brains are likely due to its inhibitory function on CBP/p300 mediated histone and p53 acetylation, thus affecting the expression of downstream genes involved in the maintenance of neuronal structure and function. Together, our data raise the possibility that alteration of EID1 expression, particularly the increase of EID1 nuclear localization that inhibits CBP/p300 activity in neuronal cells, may play an important role in AD pathogenesis. DA - 2012/03 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d52e0627-69b6-417c-9a71-7a376fb9577e ER - TY - CHAP TI - Application of bacterial glycosyltransferases in the synthesis of bioactive glycans AU - Wakarchuk, Warren T2 - Bacterial Glycomics : Current Research, Technology and Applications SN - 978-1-904455-95-0 DA - 2012/02 PY - 2012 PB - Caister Academic Press LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cad6a542-645c-4dc9-bd67-5c2a5fcb1de8 ER - TY - JOUR TI - Conical intersection dynamics in NO2 probed by homodyne high-harmonic spectroscopy DO - 10.1126/science.1208664 AU - Worner, H. J. AU - Bertrand, J. B. AU - Fabre, B. AU - Higuet, J. AU - Ruf, H. AU - Dubrouil, A. AU - Patchkovskii, S. AU - Spanner, M. AU - Mairesse, Y. AU - Blanchet, V. AU - Mevel, E. AU - Constant, E. AU - Corkum, P. B. AU - Villeneuve, D. M. T2 - Science VL - 334 IS - 6053 SP - 208 EP - 212 AB - Conical intersections play a crucial role in the chemistry of most polyatomic molecules, ranging from the simplest bimolecular reactions to the photostability of DNA. The real-time study of the associated electronic dynamics poses a major challenge to the latest techniques of ultrafast measurement. We show that high-harmonic spectroscopy reveals oscillations in the electronic character that occur in nitrogen dioxide when a photoexcited wave packet crosses a conical intersection. At longer delays, we observe the onset of statistical dissociation dynamics. The present results demonstrate that high-harmonic spectroscopy could become a powerful tool to highlight electronic dynamics occurring along nonadiabatic chemical reaction pathways. DA - 2012/08/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 7a35d2a6-1a2c-486e-84f7-9d0afe329ff0 ER - TY - JOUR TI - Effects of bending and torsion rigidity on deformation and breakage of flexible fibers : a direct simulation study DO - 10.1063/1.3685832 AU - Kabanemi, Kalonji K. AU - Hétu, Jean-François T2 - Journal of Chemical Physics VL - 136 IS - 7 SP - 074903 EP - 074911 DA - 2012/02/17 PY - 2012 PB - American Institute of Physics LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d4cba1f4-e371-451b-af0d-1437e85bdb8b ER - TY - GEN TI - Fire resistance cellulosic fibers for green polymer composites AU - Ton That, Minh Tan AU - Ngo, Tri-Dung AU - Hu, Wei T3 - COMPOSITES 2012 American Composites Manufactures Association, 21-23 February 2012, Las Vegas, Nevada, USA DA - 2012/02/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : ac7d3b3b-17f1-4fc8-90fe-bf9e7e7617c2 ER - TY - JOUR TI - Simulation of gas-substrate heat exchange during cold-gas dynamic spraying DO - 10.1016/j.ijthermalsci.2012.01.007 AU - Ryabinin, A. N. AU - Irissou, E. AU - McDonald, A. AU - Legoux, J.-G. T2 - International Journal of Thermal Sciences VL - 56 IS - June SP - 12 EP - 18 KW - biot number KW - cold spraying KW - jet impingement KW - temperature distribution number DA - 2012/02/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 89916b10-5e8c-4fd4-9591-01ff72efb6b7 ER - TY - JOUR TI - Metagenomic analysis of the bioremediation of diesel-contaminated Canadian high arctic soils DO - 10.1371/journal.pone.0030058 AU - Yergeau, Etienne AU - Sanschagrin, Sylvie AU - Beaumier, Danielle AU - Greer, Charles W. T2 - PLoS ONE VL - 7 IS - 1 SP - e30058 SP - 1 EP - 10 AB - As human activity in the Arctic increases, so does the risk of hydrocarbon pollution events. On site bioremediation of contaminated soil is the only feasible clean up solution in these remote areas, but degradation rates vary widely between bioremediation treatments. Most previous studies have focused on the feasibility of on site clean-up and very little attention has been given to the microbial and functional communities involved and their ecology. Here, we ask the question: which microorganisms and functional genes are abundant and active during hydrocarbon degradation at cold temperature? To answer this question, we sequenced the soil metagenome of an ongoing bioremediation project in Alert, Canada through a time course. We also used reverse-transcriptase real-time PCR (RT-qPCR) to quantify the expression of several hydrocarbon-degrading genes. Pseudomonas species appeared as the most abundant organisms in Alert soils right after contamination with diesel and excavation (t = 0) and one month after the start of the bioremediation treatment (t = 1m), when degradation rates were at their highest, but decreased after one year (t = 1y), when residual soil hydrocarbons were almost depleted. This trend was also reflected in hydrocarbon degrading genes, which were mainly affiliated with Gammaproteobacteria at t = 0 and t = 1m and with Alphaproteobacteria and Actinobacteria at t = 1y. RT-qPCR assays confirmed that Pseudomonas and Rhodococcus species actively expressed hydrocarbon degradation genes in Arctic biopile soils. Taken together, these results indicated that biopile treatment leads to major shifts in soil microbial communities, favoring aerobic bacteria that can degrade hydrocarbons. DA - 2012/01/11 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d293054b-6173-4df8-a3a1-17edcefdf57c ER - TY - JOUR TI - Involvement of cytochrome c CymA in the anaerobic metabolism of RDX by Shewanella oneidensis MR-1 DO - 10.1139/W11-116 AU - Perreault, Nancy N. AU - Crocker, Fiona H. AU - Indest, Karl J. AU - Hawari, Jalal T2 - Canadian Journal of Microbiology VL - 58 IS - 2 SP - 124 EP - 131 KW - RDX KW - explosive KW - nitramine KW - biotransformation KW - Shewanella AB - Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a cyclic nitramine explosive commonly used for military applications that is responsible for severe soil and groundwater contamination. In this study, Shewanella oneidensis MR-1 was shown to efficiently degrade RDX anaerobically (3.5 ?mol·h -1·(g protein) -1) via two initial routes: (1) sequential N-NO2 reductions to the corresponding nitroso (N-NO) derivatives (94% of initial RDX degradation) and (2) denitration followed by ring cleavage. To identify genes involved in the anaerobic metabolism of RDX, a library of ~2500 mutants of MR-1 was constructed by random transposon mutagenesis and screened for mutants with a reduced ability to degrade RDX compared with the wild type. An RDX-defective mutant (C9) was isolated that had the transposon inserted in the c-type cytochrome gene cymA. C9 transformed RDX at ~10% of the wild-type rate, with degradation occurring mostly via early ring cleavage caused by initial denitration leading to the formation of methylenedinitramine, 4-nitro-2,4-diazabutanal, formaldehyde, nitrous oxide, and ammonia. Genetic complementation of mutant C9 restored the wild-type phenotype, providing evidence that electron transport components have a role in the anaerobic reduction of RDX by MR-1. DA - 2012/01/19 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 841e1d7a-a1fe-4697-9012-3343f6f63e2b ER - TY - JOUR TI - A review of electrochemical desulfurization technologies for fossil fuels DO - 10.1016/j.fuproc.2012.01.022 AU - Lam, Vincent AU - Li, Guangchun AU - Song, Chaojie AU - Chen, Jinwen AU - Fairbridge, Craig AU - Hui, Rob AU - Zhang, Jiujun T2 - Fuel Processing Technology VL - 98 IS - June SP - 30 EP - 38 KW - electrochemical desulfurization KW - fossil fuel KW - heavy crude oil KW - coal KW - catalysts AB - Desulfurization is an important process for crude oil upgrading. Electrochemical desulfurization technologies have advantages over conventional hydrodesulfurization technologies in terms of lowtemperature and pressure operation with high product selectivity and therefore less energy consumption. In this paper the authors reviewed the research done in the past decades on electrochemical desulfurization for fossil fuels. The principles, electrochemical methods, electrochemical reactors, catalysts and electrolytes employed in the electrochemical desulfurization process were discussed; and future research work is recommended. DA - 2012/02/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8dda2ed4-3664-47c3-a458-aed82ed3f824 ER - TY - CHAP TI - Proton conductivity of aromatic polymers AU - Liu, Baijun AU - Guiver, Michael D. T2 - Solid State Proton Conductors : Properties and Applications in Fuel Cells SN - 9780470669372 SP - 331 EP - 369 DA - 2012/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b2c94cff-67dd-45a2-ab07-92729b708bea ER - TY - JOUR TI - Terahertz quantum cascade lasers operating up to ~ 200 K with optimized oscillator strength and improved injection tunneling DO - 10.1364/OE.20.003866 AU - Fathololoumi, S. AU - Dupont, E. AU - Chang, C. W. I. AU - Wasilewski, Z. R. AU - Laframboise, S. R. AU - Ban, D. AU - Matyas, A. AU - Jirauschek, C. AU - Hu, Q. AU - Liu, H. C. T2 - Optics Express VL - 20 IS - 4 SP - 3866 EP - 3876 AB - A new temperature performance record of 199.5 K for terahertz quantum cascade lasers is achieved by optimizing the lasing transition oscillator strength of the resonant phonon based three-well design. The optimum oscillator strength of 0.58 was found to be larger than that of the previous record (0.41) by Kumar et al. [Appl. Phys. Lett. 94, 131105 (2009)]. The choice of tunneling barrier thicknesses was determined with a simplified density matrix model, which converged towards higher tunneling coupling strengths than previously explored and nearly perfect alignment of the states across the injection and extraction barriers at the design electric field. At 8 K, the device showed a threshold current density of 1 kA/cm2, with a peak output power of ∼ 38 mW, and lasing frequency blue-shifting from 2.6 THz to 2.85 THz with increasing bias. The wavelength blue-shifted to 3.22 THz closer to the maximum operating temperature of 199.5 K, which corresponds to ∼ 1.28¯hω/κB. The voltage dependence of laser frequency is related to the Stark effect of two intersubband transitions and is compared with the simulated gain spectra obtained by a Monte Carlo approach. DA - 2012/02/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 98144fe2-7e95-448c-aa0e-06096537ad2d ER - TY - JOUR TI - Fabrication and performance of a photonic-microfluidic integrated device DO - 10.3390/mi3010062 AU - Watts, Benjamin R. AU - Kowpak, Thomas AU - Zhang, Zhiyi AU - Xu, Chang-Qing AU - Zhu, Shiping AU - Cao, Xudong AU - Lin, Min T2 - Micromachines VL - 3 IS - 1 SP - 62 EP - 77 KW - SU-8 KW - PDMS KW - microfludics KW - optical waveguide KW - integration KW - devices AB - Fabrication and performance of a functional photonic-microfluidic flow cytometer is demonstrated. The devices are fabricated on a Pyrex substrate by photolithographically patterning the microchannels and optics in a SU-8 layer that is sealed via a poly(dimethylsiloxane) (PDMS) layer through a unique chemical bonding method. The resulting devices eliminate the free-space excitation optics through integration of microlenses onto the chip to mimic conventional cytometry excitation. Devices with beam waists of 6 μm and 12 μm in fluorescent detection and counting tests using 2.5 and 6 μm beads-show CVs of 9%–13% and 23% for the two devices, respectively. These results are within the expectations for a conventional cytometer (5%–15%) and demonstrate the ability to integrate the photonic components for excitation onto the chip and the ability to maintain the level of reliable detection. DA - 2012/02/15 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 32a693ad-5082-4b37-a68b-06dc4d535456 ER - TY - JOUR TI - Effects of small specimen tilt and probe convergence angle on ADF-STEM image contrast of Si0.8Ge0.2 epitaxial strained layers on (100) Si DO - 10.1016/j.ultramic.2012.01.001 AU - Wu, X. AU - Robertson, M. D. AU - Kawasaki, M. AU - Baribeau, J.-M. T2 - Ultramicroscopy VL - 114 SP - 46 EP - 55 KW - annular dark field scanning transmission electron microscopy KW - semiconductor heteroepitaxial strained layers AB - The effects of specimen tilt and probe convergence angle on annular darkfield(ADF) image contrast of Si0.8Ge0.2 heteroepitaxial strained layers on(100) Si were investigated in a 200kV scanning transmission electron microscope (STEM) for a TEM specimen thickness of 195nm. With 0.5 degrees of specimen tilt away from the exact <011S> zone-axis orientation, the signal-to-noise level of atomic columns was significantly reduced for both Si0.8Ge0.2 and Si in high resolution ADF-STEM lattice images. When the specimen was tilted 0.5 degrees around the <011S> axis, or the STEM probe convergence semi angle was reduced from 14.3 to 3.6 mrad, the ADF-STEM image intensity profiles across the Si0.8Ge0.2 and Si layers changed significantly as compared to those obtained at the exact <011S> zone axis orientation, and no longer reflected the composition changes occurring across the layer structure. Multislice image simulation results revealed that the misfit strain between the Si0.8Ge0.2 and Silayers, and strain relaxation near the surface of the TEM specimen, were responsible for the observed changes in image intensity. DA - 2012/01/16 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0cbddbc6-7119-46da-9f06-6f2a80a99a49 ER - TY - JOUR TI - Ultracompact polarization converter with a dual subwavelength trench built in a silicon-on-insulator waveguide DO - 10.1364/OL.37.000365 AU - Velasco, Aitor, V. AU - Calvo, Maria L. AU - Cheben, Pavel AU - Ortega-Monux, Alejandro AU - Schmid, Jens H. AU - Ramos, Carlos Alonso AU - Fernandez, Inigo Molina AU - Lapointe, Jean AU - Vachon, Martin AU - Janz, Siegfried AU - Xu, Dan-Xia T2 - OPTICS LETTERS VL - 37 IS - 3 SP - 365 EP - 367 AB - The design and fabrication of an ultracompact silicon-on-insulator polarization converter is reported. The polarization conversion with an extinction ratio of 16 dB is achieved for a conversion length of only 10 m. Polarization rotation is achieved by inducing a vertical asymmetry by forming in the waveguide core two subwavelength trenches of different depths. By taking advantage of the calibrated reactive ion etch lag, the two depths are implemented using a single mask and etching process. The measured converter loss is 0.7 dB and the 3 dB bandwidth is 26 nm. DA - 2012/01/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : b30baa11-b395-4bb4-8143-a1957698e924 ER - TY - JOUR TI - Resonance-hybrid states in a triple quantum dot DO - 10.1103/PhysRevB.85.081301 AU - Amaha, S. AU - Hatano, T. AU - Tamura, H. AU - Teraoka, S. AU - Kubo, T. AU - Tokura, Y. AU - Austing, D. G. AU - Tarucha, S. T2 - Physical Review B VL - 85 IS - 8 SP - 081301-1 EP - 081301-6 AB - Delocalization by resonance between contributing structures explains the enhanced stability of resonancehybrid molecules. Here we report the realization of resonance-hybrid states in a few-electron triple quantum dot (TQD) obseved by excitation spectroscopy. The stabilization of the resonance-hybrid state and the bond between contributing states are achieved through access to the intermediate states with double occupancy of the dots. This explains why the energy of the hybridized singlet state is significantly lower than that of the triplet state. The properties of the three-electron doublet states can also be understood with the resonance-hybrid picture and geometrical phase. As well as for fundamental TQD physics, our results are useful for the investigation of materials such as quantum dot arrays, quantum information processors, and chemical reaction and quantum simulators. DA - 2012/02/02 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d7239c89-643c-4b78-852d-4fb61d8624c0 ER - TY - JOUR TI - Free-carrier absorption in quantum cascade structures DO - 10.1103/PhysRevB.85.085310 AU - Carosell, F. AU - Ndebeka-Bandou, C. AU - Ferreira, R. AU - Dupont, E. AU - Unterrainer, K. AU - Strasser, G. AU - Wacker, A. AU - Bastard, G. T2 - Physical Review B VL - 85 IS - 8 SP - 085310-1 EP - 085310-9 AB - We show that the free-carrier absorption in quantum cascade lasers (QCLs) is very small and radically different from the classical Drude result due to the orthogonality between the direction of the carrier free motion and the electric field of the laser emission. A quantum mechanical calculation of the free-carrier absorption and intersubband oblique absorption induced by interface defects, Coulombic impurities, and optical phonon absorption/emission is presented for QCLs with a double-quantum-well design. The interaction between the electrons and the optical phonons dominates at room temperature. DA - 2012/02/22 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 6ad74815-72bb-467c-a0b6-eb770157677b ER - TY - JOUR TI - Highly ordered LiFePO4 cathode material for Li-ion batteries templated by surfactant-modified polystyrene colloidal crystals DO - 10.1016/j.jpowsour.2012.01.042 AU - Yim, Chae-Ho AU - Baranova, Elena A. AU - Abu-Lebdeh, Yaser AU - Davidson, Isobel T2 - Journal of Power Sources VL - 205 SP - 414 EP - 419 KW - LiFePO4 KW - Li-ion battery KW - cathode material KW - three-dimensionally ordered macroporous structure KW - organic template assisted synthesis AB - An organic template assisted synthesis was developed to obtain highly ordered porous LiFePO4 cathode material. The developed synthesis enabled the use of polystyrene (PS) as template by modifying its surface with a surfactant (Brij 78) to render it hydrophilic. The material was synthesized in high yield and purity as confirmed by X-ray powder diffraction. The TEM and SEM images clearly confirmed the presence of a highly ordered porous structure and the latter showed that the structure has an average pore diameter of 400 nm and a wall thickness and depth of ~100 nm. Thermal scans and elemental analysis showed that the material contains a high amount of carbon reaching 23-28% by weight. The surface area was calculated using the BET method and found to be 7.71m(to the power of 2)g(to the power of-1). Li/LiFePO4 half cells were tested and gave satisfactory discharge capacities; an initial capacity [158mAhg(to the power of -1)] close to the theoretical value and recoverable capacities at high C-rates (2-5 C). DA - 2012/01/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : f44190dc-f6a7-4320-b781-44460cccee7f ER - TY - JOUR TI - Optimization of synthesis conditions for LiFePO4/C nanocomposites by dimethyl sulfoxide assisted solution-phase method DO - 10.1149/2.004204jes AU - Chang, Zhaorong AU - Tang, Hongwei AU - Liu, Yao AU - Yuan, Xiao Zi AU - Wang, Haijiang AU - Gao, Shuyan T2 - Journal of the Electrochemical Society VL - 159 IS - 4 SP - A331 EP - A335 KW - olivine-type LiFePO4 KW - dimethyl sulfoxide (DMSO) KW - X-ray diffraction (XRD) KW - nanocomposites AB - Olivine-type LiFePO4 is synthesized by a solution-phase method, using dimethyl sulfoxide (DMSO) as a boiling point raiser and crystal growth inhibitor under ambient pressure and low temperature for a short time. The crystalline structure and morphology of the composites are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. By analyzing the ratio of solvent to water, reactant concentration, reaction time, sintering time, and temperature we determine the optimal conditions for synthesizing LiFePO4/C nanocomposites, which are as follows: DMSO:water = 1:1, reactant concentration 1 M, reaction time 2 h, mixed with a certain amount of glucose and sintered at 600◦C under a 5% H2–95% N2 atmosphere for 3 h. The LiFePO4/C thus prepared has a well developed olivine-type structure, small crystals, and a narrow size distribution. Electrochemical performance tests show that the special capacity of LiFePO4/C at discharge rates of 0.2 C and 1 C is 157.7 mAh g−1 and 142.5 mAh g−1, respectively. A special capacity of 126 mAh g−1 at 5 C and 104 mAh g−1 at 10 C is even achievable, with no significant capacity fading after 200 cycles, and thematerial delivers a good high-rate discharge property and excellent cycling performance. DA - 2012/01/18 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : a398a3cb-004e-4eea-89dd-61d5f66cc09f ER - TY - JOUR TI - Effect of open circuit voltage on degradation of a short proton exchange membrane fuel cell stack with bilayer membrane configurations DO - 10.1016/j.jpowsour.2012.01.031 AU - Zhang, Shengsheng AU - Yuan, Xiao-Zi AU - Hiesgen, Renate AU - Friedrich, K. Andreas AU - Wang, Haijiang AU - Schulze, Mathias AU - Haug, Andrea AU - Li, Hui T2 - Journal of Power Sources VL - 205 SP - 290 EP - 300 KW - PEM fuel cell KW - twin-CCM KW - degradation KW - membrane KW - open circuit voltage AB - In the present work, membrane electrode assembly degradation of a 4-cell stack with specially designed twin catalyst coated membranes (twin-CCMs) was carried out for 1600 h under open circuit voltage (OCV) conditions. Four types of membrane with various thicknesses were employed in the experiment. Each twin-CCM was composed of two membranes of the same type with a catalyst layer coated only on one side. The purpose of this special configuration was to facilitate postmortem analysis of the membrane after degradation due to the detachable membrane structure. By means of several in situ electrochemical measurements, the performance of the individual cells was analysed every 200 h during the degradation process. Postmortem analyses such as scanning electron microscopy, atomic force microscopy, and infrared imaging were also conducted to identify the membrane degradation mechanisms after exposure to OCV. The results indicate that membrane degradation, which correlates with electrode degradation, is the most direct reason for the failure of the whole cell/stack during OCV operation, especially for cells with thinner membranes. DA - 2012/01/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 68f0aeb9-5c3b-4784-ab11-060ac244e82f ER - TY - JOUR TI - Degradation of a PEM fuel cell stack with Nafion® membranes of different thicknesses. Part II : Ex situ diagnosis DO - 10.1016/j.jpowsour.2012.01.074 AU - Yuan, Xiao-Zi AU - Zhang, Shengsheng AU - Ban, Shuai AU - Huang, Cheng AU - Wang, Haijiang AU - Singara, Vengatesan AU - Fowler, Michael AU - Schulze, Mathias AU - Haug, Andrea AU - Friedrich, K. Andreas AU - Hiesgen, Renate T2 - Journal of Power Sources VL - 205 SP - 324 EP - 334 KW - proton exchange membrane fuel cell KW - stack KW - ex situ KW - durability KW - idle conditions KW - degradation AB - Part I of this study carried out membrane electrode assembly degradation of a four-cell stack with Nafion membranes of different thicknesses, including N117, N115, NR212, and NR211, for 1000 h under idle conditions. Through on-line electrochemical measurements it was found that as degradation advanced, cells with thinner membranes experienced much more rapid performance degradation than those with thicker membranes, especially after 800 h of operation, due to a dramatic increase in hydrogen crossover. In the present work we investigate the degradation mechanisms of this four-cell stack using several ex situ diagnostic tools, including scanning electron microscopy (SEM), infrared (IR) imaging, ion chromatography (IC), gas permeability measurement, contact angle measurement, and simulation. The results indicate that the drastic increase in hydrogen crossover is due to membrane thickness loss and pinhole formation. DA - 2012/01/21 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 833eb7d8-d09f-437f-b1a6-26464513d027 ER - TY - JOUR TI - A review on performance degradation of proton exchange membrane fuel cells during startup and shutdown processes : causes, consequences, and mitigation strategies DO - 10.1016/j.jpowsour.2012.01.059 AU - Yu, Yi AU - Li, Hui AU - Wang, Haijiang AU - Yuan, Xiao-Zi AU - Wang, Guangjin AU - Pan, Mu T2 - Journal of Power Sources VL - 205 SP - 10 EP - 23 KW - proton exchange membrane fuel cell KW - startup and shutdown process KW - hydrogen/air interface KW - reverse current KW - system strategies AB - Performance degradation during startup and shutdown is considered an important issue affecting the durability and lifetime of proton exchange membrane fuel cells (PEMFCs). Due to the high potentials experienced by the cathode during startup and shutdown, the conventional carbon support for the cathode catalyst is prone to oxidation by reacting with oxygen or water. This paper presents an overview of the causes and consequences of performance degradation after frequent startup shutdown cycles. Mitigation strategies are also summarized, including the use of novel catalyst supports and the application of system strategies to prevent performance degradation in PEMFCs. It is found from the literature review that improvements in catalyst supports to prevent oxidation come at the expense of high cost, and the novel supports developed to date are not sufficient to completely prevent carbon oxidation in fuel cell engines. System strategies, including potential control and reaction gas control, have been developed and applied in fuel cell engines to alleviate or even avoid performance decay. This review aims to provide a clear understanding of the mechanisms related to degradation behaviors during the startup and shutdown processes, thereby helping fuel cell material or system developers in their efforts to prevent performance degradation and prolong the lifetime of PEMFCs. DA - 2012/01/20 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 9fa1f4d8-9104-47e3-9e85-eb2eb58d372b ER - TY - JOUR TI - Appetite regulation and weight control : the role of gut hormones DO - 10.1038/nutd.2011.21 AU - Perry, B. AU - Wang, Y. T2 - Nutrition and Diabetes VL - 2 SP - e26-1 EP - e26-7 KW - obesity KW - appetite KW - hypothalamus KW - gut hormones AB - The overwhelming increase in the prevalence of overweight and obesity in recent years represents one of the greatest threats to the health of the developed world. Among current treatments, however, gastrointestinal (GI) surgery remains the only approach capable of achieving significant weight loss results with long-term sustainability. As the obesity prevalence approaches epidemic proportions, the necessity to unravel the mechanisms regulating appetite control has garnered significant attention. It is well known that physical activity and food intake regulation are the two most important factors involved in body weight control. To regulate food intake, the brain must alter appetite. With this realization has come increased efforts to understand the intricate interplay between gut hormones and the central nervous system, and the role of these peptides in food intake regulation through appetite modulation. This review discusses the central mechanisms involved in body weight regulation and explores a suite of well characterized and intensely investigated anorexigenic and orexigenic gut hormones. Their appetite-regulating capabilities, post-GI surgery physiology and emerging potential as anti-obesity therapeutics are then reviewed. DA - 2012/01/16 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fca2469a-6cd0-4fe5-86ee-2601c95447bf ER - TY - JOUR TI - Accelerated conditioning for a proton exchange membrane fuel cell DO - 10.1016/j.jpowsour.2012.01.039 AU - Yuan, Xiao-Zi AU - Sun, Jian Colin AU - Wang, Haijiang AU - Li, Hui T2 - Journal of Power Sources VL - 205 SP - 340 EP - 344 KW - conditioning KW - pre-conditioning KW - activating KW - commissioning KW - break-in AB - A conditioning process is usually needed for a newly fabricated proton exchange membrane (PEM) fuel cell to be activated. Depending on the membrane electrode assemblies, this process can take hours and even days to complete. To provide for accelerated conditioning techniques that can complete the process in a short time, this paper compares various reported methods to condition a PEM single cell. The major objectives are to identify accelerated conditioning approaches that can significantly reduce the conditioning duration for the existing conditioning regime in an operationally easy manner, and to understand the fundamental principles that govern accelerated conditioning. Various effects investigated include temperature, cycling steps, and cycling frequencies. Other techniques, such as short circuiting, hydrogen pumping, and hot water circulation, are also discussed. For each technique, measurements are taken using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and linear sweep voltammetry (LSV). DA - 2012/01/10 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 24ca7dbb-bdda-4a21-90ff-f7b32aca251f ER - TY - JOUR TI - Aerobic and anaerobic operation of an active membraneless direct methanol fuel cell DO - 10.1016/j.elecom.2011.12.020 AU - Lam, Alfred AU - Dara, Mohammad S. AU - Wilkinson, David P. AU - Fatih, Khalid T2 - Electrochemistry Communications VL - 17 SP - 22 EP - 25 KW - Membraneless KW - Direct methanol fuel cell KW - Direct methanol redox fuel cell KW - Aerobic KW - Anaerobic AB - In this paper the operational and architectural flexibilities of a membraneless direct liquid fuel cell were demonstrated under aerobic and anaerobic configurations at 60 C and 1 atm. The aerobic membraneless direct methanol fuel cell (DMFC) was fed an anolyte solution of 1 MCH3OH/0.5 MH2SO4 and an air oxidant. The anaerobic membraneless direct methanol redox fuel cell (DMRFC) was fed an anolyte solution of 1 M CH3OH/0.1 M HClO4 and a catholyte solution of 2 M Fe(ClO4)3 and 0.22 M Fe(ClO4)2 oxidant. For both cases the membraneless architecture performed significantly better than for the conventional PEM architecture with Nafion 117. The maximum power density for the membraneless and Nafion 117 based DMFC was 52 mW cm 2 and 41 mW cm 2 respectively. The maximum power density for the membraneless and Nafion 117 based DMRFC was 46mW cm 2 and 34mW cm 2 respectively. In addition, anaerobic operation using a Fe2 /Fe3 catholyte gave similar performance to that for air as an oxidant. Both membraneless and anaerobic operation can result in significant cost reduction with improved operational flexibility. DA - 2012/01/09 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 71487c8d-895c-47f4-a626-213b2e9dbb1f ER - TY - JOUR TI - Non-contact detection of ultrasound applied to biomedical photoacoustic tomography and ultrasonography AU - Rousseau, Guy AU - Blouin, Alain AU - Monchalin, Jean-Pierre T2 - Proceedings of SPIE--the international society for optical engineering T3 - SPIE Medical Imaging 2012 : Physics of Medical Imaging, Feb. 5, 2012, San Diego, California, USA, 2012-02-05, San Diego, California, USA VL - 8313 DA - 2012/02/05 PY - 2012 PB - SPIE LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : fea7e704-a8e1-46dc-9545-8b5abfcf3ffe ER - TY - JOUR TI - Swept-source OCT using programmable laser AU - Lamouche, Guy AU - Vergnole, Sébastien AU - Kim, Youngjae AU - Burgoyne, Bryan AU - Villeneuve, Alain T2 - SPIE Proceedings: Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XVI T3 - Photonics West 2012, Jan 21-26, 2012, San Francisco, California, USA, Jan 21-26, 2012, San Francisco, California, USA VL - 8213 SP - 8213-122 Poster Session DA - 2012/01/27 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : bd57ce2c-ed4b-4749-9900-359948a15890 ER - TY - JOUR TI - PW12B-BO103-22 real-time control of angioplasty balloon inflation based on feedback from intravascular optical coherence tomography AU - Azarnoush, Hamed AU - Vergnole, Sébastien AU - Lamouche, Guy T2 - Photonics West 2012 T3 - Photonics West 2012 : SPIE BiOS, Jan 26, 2012, San Francisco, California, USA, Jan 23-26, 2012, San Francisco, California, USA DA - 2012/01/24 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 5deace78-80ac-46f3-8d67-83f89efd213a ER - TY - JOUR TI - Non-contact photoacoustic tomography and ultrasonography for biomedical imaging DO - 10.1117/12.906874 AU - Rousseau, Guy AU - Levesque, Daniel AU - Blouin, Alain AU - Monchalin, Jean-Pierre AU - Oraevsky, Alexander A. AU - Wang, Lihong V. T2 - Photons plus ultrasound : imaging and sensing 2012 T2 - Proceedings of SPIE; 8223 T3 - 2012 SPIE Photonics West, 21-26 January 2012, San Francisco, California, USA, 21-26 January 2012, San Francisco, California, USA SN - 9780819488664 KW - biomedical imaging KW - photoacoustic tomography KW - ultrasonography KW - laser ultrasonics KW - laser safety limits KW - tissue imaging KW - chicken breast DA - 2012/03/08 PY - 2012 PB - SPIE--the International Society for Optical Engineering LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 56b1c6ca-61aa-45b6-96d6-2a3290977613 ER - TY - JOUR TI - Non-contact photoacoustic tomography and ultrasonography for brain imaging DO - 10.1117/12.906871 AU - Rousseau, Guy AU - Blouin, Alain AU - Monchalin, Jean-Pierre T2 - Photonic Therapeutics and Diagnostics VIII T2 - Proceedings of SPIE; 8207 T3 - 2012 SPIE Photonics West , 21-26 January 2012, San Francisco, California, USA, San Francisco, USA KW - biomedical imaging KW - photoacoustic tomography KW - ultrasonography KW - non-contact detection KW - neurosurgery KW - brain KW - blood oxygenation KW - ischemia DA - 2012/03/08 PY - 2012 PB - SPIE--the International Society for Optical Engineering LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cd2f4cce-c72b-4e69-8fe4-2f25a3ac48cf ER - TY - JOUR TI - CO optical sensing properties of nanocrystalline ZnO-Au films: Effect of doping with transition metal ions DO - 10.1016/j.snb.2011.11.011 AU - Della Gaspera, E. AU - Guglielmi, M. AU - Perotto, G. AU - Agnoli, S. AU - Granozzi, G. AU - Post, M. L. AU - Martucci, A. T2 - Sensors and actuators B: Chemical VL - 161 IS - 1 SP - 675 EP - 683 KW - Nanoparticles KW - Nanocomposite KW - Thin films KW - Sensors AB - Zinc oxide nanocrystals, pure and doped with transition metal ions, have been synthesized using colloidal techniques; after purification and concentration protocols, the ZnO solutions are mixed with monodisperse Au colloidal suspensions and used for thin film depositions. The effect of the dopant ions on the structural, morphological and optical properties of the as-synthesized colloids as well as the nanocomposite thin films has been analyzed and discussed. The dopant presence has been found to affect the CO optical sensing properties of the nanocomposite ZnO–Au films: compared to pure ZnO, an increase in sensitivity up to 80 percent and 55 percent has been detected for Co-doped and Mn-doped ZnO respectively, while Ni-doped ZnO films show only minor improvements. This observation has been ascribed to the multiple oxidation states of cobalt and manganese ions that can facilitate electron transfer between the target gas and semiconductive oxide matrix, and also to the lower surface concentration of Ni ions inside ZnO crystals, as compared to Co and Mn. A fast and reversible response after repeated CO exposures has been detected for all tested samples, and a linear response intensity with the order of magnitude of CO concentration has been observed in the 10–10,000 ppm range, with a lower detection limit of 1–2 ppm. DA - 2012/01/03 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 1bc3d2ab-5033-403e-86d4-aae04b132464 ER - TY - JOUR TI - Investigation of CrSi2 and MoSi2 as anode materials for lithium-ion batteries DO - 10.1016/j.jpowrsour.2011.11.047 AU - Courtel, Fabrice M. AU - Duguay, Dominique AU - Abu-Lebdeh, Yaser AU - Davidson, Isobel J. T2 - Journal of Power Sources VL - 202 SP - 269 EP - 275 KW - CrSi2 KW - MoSi2 KW - Silicide KW - Li-ion batteries KW - Anode material AB - We report on the suitability of the two metal silicides MoSi 2 and CrSi 2 as anode materials for Li-ion batteries. The two materials were synthesized by high energy ball milling of the corresponding metals and X-ray diffraction was used to follow the evolution/formation of the crystalline phases. The in-house prepared powders have shown better battery performance than commercial powders (as-received or ball-milled). We observed that 20 h were necessary for the formation of MoSi 2 whereas 100 h were needed for the formation of the CrSi 2 powder. The best battery performance was obtained with the synthesized CrSi 2 powder that has a theoretical capacity value of 469 mAh g-¹. This powder provided capacities of 340, 262, 167, 110, and 58 mAh g-¹ at C/12, C/6, C/2, C, and 2C, respectively. Cycling at 60 °C showed higher capacity values, but with a faster fade of these values. DA - 2012/03/15 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 3a1e8729-81d6-4410-bc97-45d36fd026a1 ER - TY - JOUR TI - The classical-map hyper-netted-chain (chnc) method and associated novel density-functional techniques for warm dense matter DO - 10.1002/qua.23170 AU - Dharma-Wardana, M. W. C. T2 - International Journal of Quantum Chemistry VL - 112 IS - 1 SP - 53 EP - 64 KW - density functional therapy KW - warm dense matter KW - CHNC-pair distributions KW - fermi liquids KW - Hugoniot AB - The advent of short-pulse lasers, nanotechnology, as well as shock-wave techniques have created new states of matter (e.g., warm dense matter) that call for new theoretical tools. Ion correlations, electron correlations, as well as bound states, continuum states, partial degeneracies and quasi-equilibrium systems need to be addressed. Bogoliubov’s ideas of timescales can be used to discuss the quasi-thermodynamics of nonequilibrium systems. A rigorous approach to the associated many-body problem turns out to be the computation of the underlying pair-distribution functions gee, gei, and gii, that directly yield nonlocal exchange-correlation potentials, free energies etc., valid within the timescales of each evolving system. An accurate classical map of the strongly-quantum uniform electron-gas problem given by Dharma-wardana and Perrot is reviewed. This replaces the quantum electrons at T = 0 by an equivalent classical fluid at a finite temperature Tq, and having the same correlation energy. The classical map is used with classical molecular dynamics (CMMD) or hyper-netted-chain integral equations (CHNC) to determine the pair-distribution functions (PDFs), and hence their thermodynamic and linear transport properties. The CHNC is very efficient for calculating the PDFs of uniform systems, while CMMD is more adapted to nonuniform systems. Applications to 2D and 3D quantum fluids, Si metal-oxide-field-effect transistors, Al plasmas, shock-compressed deuterium, two-temperature plasmas, pseudopotentials, as well as calculations for parabolic quantum dots are reviewed. DA - 2012/01/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : c3d741a5-8d20-4dda-9e7e-36789d54a728 ER - TY - JOUR TI - In situ measurement and modelling of austenite grain growth in a Ti/Nb microalloyed steel DO - 10.1016/j.actamat.2011.11.016 AU - Maalekian, M. AU - Radis, R. AU - Militzer, M. AU - Moreau, A. AU - Poole, W. J. T2 - Acta Materialia VL - 60 IS - 3 SP - 1015 EP - 1026 KW - Austenite grain growth KW - Laser ultrasonics KW - Microalloyed steel KW - Precipitation kinetics KW - Grain growth modelling AB - Using a novel laser ultrasonics technique in situ measurements of austenite grain growth were conducted during continuous heating (10 °C s−1) and subsequent isothermal holding at various temperatures in the range 950–1250 °C in a microalloyed linepipe steel. Based on the experimental results, a grain growth model was developed, which includes the pinning effect of precipitates present in the steel. Analyzing the grain growth behaviour and using the advanced thermo-kinetic software MatCalc, an approach was developed to estimate the initial distribution of precipitates in the as-received material and their dissolution kinetics. The evolution of the volume fractions and mean particle sizes of NbC and TiN leads to a time-dependent pinning pressure that is coupled with the proposed grain growth model to successfully describe the observed kinetics of austenite grain growth. The predictive capabilities of the model are illustrated by its application to independent grain growth data for rapid heat treatment cycles that are typical of the weld heat affected zone. DA - 2012/02/01 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 457813a2-ac40-466c-9633-c16ed3dc49e8 ER - TY - JOUR TI - Mechanical properties of thermomechanically-processed metastable beta Ti-Nb-Zr alloys for biomedical applications DO - 10.4028/www.scientific.net/MSF.706-709.455 AU - Braïlovski, Vladimir AU - Gauthier, Maxime AU - Prokoshkin, Sergei AU - Inaekyan, Karine AU - Dubinskiy, Sergei AU - Zhukova, Yulia T2 - Materials science forum T3 - THERMEC 2011; International conference on processing and manufacturing of advanced materials processing, fabrication, properties, applications, August 1-5, 2011, Quebec City, Canada, August 1-5, 2011, Quebec City, Canada VL - 706-709 SP - 455 EP - 460 KW - shape memory alloys KW - titanium alloys KW - thermomechanical processing (TMP) KW - biomedical applications AB - Metastable beta-titanium alloys combine exceptionally low Young's modulus and high biocompatibility, thus attracting special interest in the prospect of their application as biomedical implant material. In this work, Ti-21.8Nb-6Zr (at. percent) ingots were manufactured by vacuum argon melting followed by hot isothermal pressing. The obtained ingots were thermomechanically processed using the following TMP sequence: a) cold rolling (CR) from e=0.37 to 2 of the logarithmic thickness reduction; and b) post-deformation annealing (PDA) of between 450 and 700oC (10’…5 h for 600oC and 1 h for other temperatures). The influence of the TMP on the alloy’s mechanical properties under static and cyclic loading was studied. DA - 2012/01/01 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8c7836f8-c4ba-4210-838a-4c5c783486d8 ER - TY - JOUR TI - Characterization of polypropylene composites reinforced with flax fibers treated by mechanical and alkali method DO - 10.1515/secm.2011.011 AU - Hu, Wei AU - Ton-That, Minh-Tan AU - Denault, Johanne AU - Belanger, Christian T2 - Science and Engineering of Composite Materials VL - 18 IS - 1-2 SP - 79 EP - 85 KW - alkaline treatment KW - flax KW - mechanical treatment KW - polypropylene composites KW - shive AB - Flax is a type of natural fiber widely used as reinforcing materials for polymer composites. The commercially available flax fibers in Canada consist of a significant amount of shive and other impurities, which could act as stress concentration regions to negatively affect the mechanical property of composites. In this study, the shive was manually removed from the commercial flax fibers by screening and combing to obtain different shive contents from 0 to 30 wt percentage. By contrast, the obtained flax fibers were further treated with alkaline solution. The fibers obtained from mechanical and alkali treatment were compared on their thermal and mechanical properties. As expected, it was found that the thermal stability and mechanical properties of the flax reinforced polypropylene composites increased significantly with the removal of the shive content. However, the alkali treatment on flax fiber did not further improve the composites properties. The possible reason was that the proper mechanical treatment (screening and combing) prior to alkaline treatment effectively loosened the fiber bundles for better single fiber separation in matrix and significantly removed the impurities, thus the effect of alkaline treatment did not become obvious. DA - 2012/01/09 PY - 2012 PB - Walter de Gruyter LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : d7b63570-25e9-4e2a-96fc-399544ded50e ER - TY - JOUR TI - Mechanical properties of porous metastable beta Ti-Nb-Zr alloys for biomedical applications DO - 10.1016/j.jallcom.2011.12.157 AU - Braïlovski, V. AU - Prokoshkin, S. AU - Gauthier, M. AU - Inaekyan, K. AU - Dubinskiy, S. T2 - Journal of alloys and compounds T3 - ICOMAT 2011: International Conference on Martensitic Transformations, September 4-9, 2011, Osaka, Japan, 2011-09-04 VL - 577 IS - Supplement 1 SP - S413 EP - S417 KW - Metals and alloys KW - Powder metallurgy KW - Sintering KW - Mechanical properties KW - Shape memory AB - For this study, Ti–(20–22)Nb–(5–6)Zr (at percent) ingots were manufactured by vacuum and argon arc melting. The obtained ingots were divided into two batches: the first subjected to cold rolling (CR) from 30 to 85 percent of thickness reduction, and subsequent annealing in the 450–600 °C temperature range (1 h). Regardless of the CR intensity, Ti–Nb–Zr samples subjected to 600 °C annealing showed the highest fatigue resistance during room-temperature cumulative cycling due to the stress-induced martensitic transformation occurring in the polygonized dislocation substructure (average subgrain size ∼ 100 nm). The second batch was atomized to produce 100-μm-size powders in order to manufacture open-cell porous material (cell size vary from 136 to 561 μm) of 46 percent porosity by means of powder metallurgy using a polymer-based foaming process. Tensile, compression and bending testing were performed at RT on foam samples annealed at 450–600 °C (1 h). Results indicated that Young's modulus of Ti–Nb–Zr foams significantly decreases as compared to the as-sintered material: when annealing temperature increases from 450 to 600 °C, Young's modulus decreases from 10 ± 2 GPa to 6 ± 1 GPa. Under the same testing conditions, Ti-CP foams produced by the same technology and having similar porosity remain fairly insensible to post-sintering annealing. DA - 2012/02/06 PY - 2012 PB - Elsevier LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 8e4a22b1-1d73-4f94-98b0-d9e90fa30567 ER - TY - CHAP TI - Molecular Mechanisms of Neuroinflammation in Alzheimer's Disease AU - Vukic, Vanja AU - Callaghan, Debbie AU - Liu, Hong AU - Zhang, Wandong AU - Gemma, Carmelina T2 - Neuroinflammation : Pathogenesis, Mechanisms and Management SN - 978-1-61942-462-3 DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 22cabf3f-08d0-4497-a6fc-a02bd6ccad4b ER - TY - JOUR TI - Culturing and electrophysiology of cells on NRCC patch-clamp chips DO - 10.3791/3288 AU - Py, Christophe AU - Martina, Marzia AU - Monette, Robert AU - Comas, Tanya AU - Denhoff, Mike W. AU - Luk, Collin AU - Syed, Naweed I. AU - Mealing, Geoff T2 - Journal of visualized experiments IS - 60 SP - 1 EP - 5 KW - Neuroscience KW - Issue 60 KW - disease models KW - pharmaceutical screens KW - electrophysiological recordings KW - patch-clamp KW - silicon planar patch-clamp chip KW - cultured neurons AB - Due to its exquisite sensitivity and the ability to monitor and control individual cells at the level of ion channels, patch-clamping is the gold standard of electrophysiology applied to disease models and pharmaceutical screens alike 1. The method traditionally involves gently contacting a cell with a glass pipette filled by a physiological solution in order to isolate a patch of the membrane under its apex 2. An electrode inserted in the pipette captures ion-channel activity within the membrane patch or, when ruptured, for the whole cell. In the last decade, patch-clamp chips have been proposed as an alternative 3, 4: a suspended film separates the physiological medium from the culture medium, and an aperture microfabricated in the film replaces the apex of the pipette. Patch-clamp chips have been integrated in automated systems and commercialized for high-throughput screening 5. To increase throughput, they include the fluidic delivery of cells from suspension, their positioning on the aperture by suction, and automated routines to detect cell-to-probe seals and enter into whole cell mode. We have reported on the fabrication of a silicon patch-clamp chip with optimized impedance and orifice shape that permits the high-quality recording of action potentials in cultured snail neurons 6; recently, we have also reported progress towards interrogating mammalian neurons 7. Our patch-clamp chips are fabricated at the Canadian Photonics Fabrication Centre 8, a commercial foundry, and are available in large series. We are eager to engage in collaborations with electrophysiologists to validate the use of the NRCC technology in different models. The chips are used according to the general scheme represented in Figure 1: the silicon chip is at the bottom of a Plexiglas culture vial and the back of the aperture is connected to a subterranean channel fitted with tubes at either end of the package. Cells are cultured in the vial and the cell on top of the probe is monitored by a measuring electrode inserted in the channel.The two outside fluidic ports facilitate solution exchange with minimal disturbance to the cell; this is an advantage compared to glass pipettes for intracellular perfusion. DA - 2012/02/07 PY - 2012 PB - MYJoVE Corp LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 79045277-4ce7-41ef-870f-fc931d26a1a9 ER - TY - JOUR TI - Multifunctional nanoprobes for pathogen-selection capture and detection DO - 10.1039/C1CC16245D AU - Paquet, Chantal AU - Ryan, Shannon AU - Zou, Shan AU - Kell, Arnold AU - Tanha, Jamshid AU - Hulse, John AU - Tay, Li-Lin AU - Simard, Benoit T2 - Chemical communications VL - 48 IS - 4 SP - 561 EP - 563 AB - The synthesis of magnetic and fluorescent particles is described. The particles are biofunctionalized by binding pathogen-specific proteins to the particles via interactions between His-tags of proteins and zinc of the quantum dots. Detection of Salmonella and Staphylococcus aureus (S. aureus) by these particles is demonstrated. DA - 2012/01/14 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : cd9f5e61-7df3-4893-bf6f-ec038ec1d94f ER - TY - JOUR TI - Comparison between dew-retted and enzyme-retted flax fibers as reinforcing material for composites DO - 10.1002/pen.22060 AU - Hu, Wei AU - Ton-That, Minh-Tan AU - Denault, Johanne AU - Rho, Denis AU - Yang, Jianzhong AU - Lau, Peter C.K. T2 - Polymer Engineering and Science VL - 52 IS - 1 SP - 165 EP - 171 AB - Two kinds of retted Canadian linseed flax fibers, dew-retted (F1) and enzyme-retted flax fibers (F2) were characterized in detail for their applications in composites, such as retting degree, thermal stability, tensile strength, and interfacial behavior in polypropylene (PP) matrix. It's clear from Scanning Electron Micrograph that the aspect ratio of F2 was much higher than that of F1 in the light of their separated elementary fibers in most cases. Instead, the elementary fibers of F1 remained tightly bundled into technical fiber wrapping with more non-cellulose portions. This reflected its lower retting degree and resulted in its lower thermal stability. Single fiber tensile test and single fiber pull-out test were used to evaluate the fiber tensile properties and fiber/PP interfacial shear strength, respectively. Better retting degree and fewer damages on F2 endowed F2 better tensile property. Consequently, higher aspect ratio, retting degree, and tensile strength proved F2 to be a kind of better reinforcing material than F1 for composites. DA - 2012/01/01 PY - 2012 PB - Society of Plastics Engineers / Wiley LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : e6cff8f8-ede5-4aad-afd2-c0a2d4a8d78e ER - TY - CHAP TI - The role of sialic acid in the formation of protective conformational bacterial polysaccharide epitopes DO - 10.1007/978-3-7091-0870-3_3 AU - Jennings, Harold J. AU - Kosma, Paul AU - Müller-Loennies, Sven T2 - Anticarbohydrate Antibodies : From Molecular Basis to Clinical Application SN - 978-3-7091-0869-7 SP - 55 EP - 73 DA - 2012 PY - 2012 PB - Springer-Verlag/Wien LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 69e4f3a9-7eac-4c45-af11-5857df596527 ER - TY - JOUR TI - Who are our clients: consumer segmentation through explorative data mining DO - 10.1504/IJDMMM.2012.048109 AU - Viktor, Herna L. AU - Peña, Isis AU - Paquet, Eric T2 - International Journal of Data Mining, Modelling and Management SN - 1759-1163 VL - 4 IS - 3 SP - 286 EP - 308 KW - Utility-based data mining KW - anthropometry KW - interestingness measures KW - consumer segmentation KW - marketing AB - The apparel industry aims to produce comfortable and aesthetically pleasing garments that fit populations well. However, repeated studies of apparel customers' levels of satisfaction indicate that their needs are often not being met. In order to produce better fitting clothes, it is crucial to understand the body profiles of typical consumers. Exploring the demographic profiles of correctly identified customer segments holds obvious benefit for production, marketing and ensuring return on investments. To this end, we explore a database, containing anthropometric measurements, demographic profiles and 3-D body scans, of samples of the North American, Italian and Dutch populations. Through the use of objective interestingness measures-based feature selection and feature extraction, we accurately discover the relevant subsets of body measurements that require special care when designing clothes. Furthermore, we apply association analysis to the demographic data, in order to target customers and thus potentially defining new market opportunities. Copyright © 2012 Inderscience Enterprises Ltd. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 0af3f5d6-bb66-40a4-b6fd-0f3272eb5bd5 ER - TY - JOUR TI - Laser-ultrasonic austenite grain size measurements in low-carbon steels DO - 10.4028/www.scientific.net/MSF.715-716.407 AU - Militzer, Matthias AU - Moreau, André AU - Maalekian, Mehran T2 - Recrystallization and grain growth IV : selected, peer reviewed papers from the Fourth International Conference on Recrystallization and Grain Growth, (ReX & GG 2010), July 4-9, 2010, Sheffield, UK T2 - Materials Science Forum; Volume 715-716 T3 - Fourth International Conference on Recrystallization and Grain Growth, July 4-9, 2010, Sheffield, England SN - 0255-5476 SN - 9783037853900 SP - 407 EP - 414 KW - Austenite decomposition KW - Austenite grain size KW - Austenite microstructure KW - Laser-generated ultrasound KW - Steel samples KW - Thermo-mechanical processing KW - Grain growth KW - Isotherms KW - Low carbon steel KW - Microstructure KW - Recrystallization (metallurgy) KW - Ultrasonic applications AB - Austenite grain size is an important microstructure parameter when processing steels as it provides the initial condition for the austenite decomposition that determines the final microstructure and thus properties of the steel. In low-carbon steels it is frequently difficult if not impossible to quantify the austenite grain size using conventional metallographic techniques. Laserultrasonics provides an attractive alternative to quantify the grain size in-situ during thermomechanical processing of a steel sample. The attenuation of the laser generated ultrasound wave is a function of the grain size. The present paper gives an overview on the state-of-the-art of this novel measurement technique. Using isothermal and non-isothermal grain growth tests in low-carbon steels the advantages and limitations of laser-ultrasonic measurements will be demonstrated. Further, their application for deformed samples will be presented to quantify austenite grain sizes during and after recrystallization. The in-situ measurements provide significantly new insights into the austenite microstructure evolution during thermo-mechanical processing of low-carbon steels. The implications on expediting the development of improved process models will be discussed. © (2012) Trans Tech Publications, Switzerland. DA - 2012 PY - 2012 LA - eng C1 - Collection / Collection : NRC Publications Archive / Archives des publications du CNRC C2 - Record identifier / Identificateur de l’enregistrement : 661a5441-4fb8-4fd7-80ed-7d37bc1fa42c ER -