Synthesis Of Diamond-Like Carbon By Pecvd On Different Substrates For Fuel Cell Applications

Lower cost, lighter weight, and higher electrical conductivity are among many advantages of using metallic bipolar plates (BPs) over the conventional graphitic materials in PEM fuel cell applications. In this study, diamond-like carbon (DLC) coatings are deposited on top surfaces of stainless steel (SS316) and Aluminum (Al5052) substrates via Plasma Enhanced Carbon Vapor Deposition (PECVD) in order to increase the durability. Further, the effect of different plasma power intensities and type of precursor gases, including methane (CH4) and acetylene (C2H2), on the growth of DLC films is studied. Various ex-situ characterization techniques have been used to examine the strength of adhesion, morphologies, structures/compositions, and wettability of the DLC coatings. It is found that coatings produced from CH4 gas show superior adhesion in comparison to those obtained from the C2H2 gas. Results indicate that higher deposition power intensity can produce more sp3 bonds than sp2 bonds. It is also determined that the type of the metallic substrates has predominant roles on the morphology of the DLC coatings. In addition, a moderate power intensity of 250 W results in desirable properties in DLC, including adhesion and wettability, compared to higher and lower plasma power intensities

Measurements of left ventricular myocardial longitudinal systolic displacement using spectral and colour tissue Doppler: time for a reassessment?

<p>Abstract</p> <p>Background</p> <p>Echocardiographic measurements of left ventricular (LV) myocardial displacement may produce different results depending on the choice of employed modality and subjective adjustments during data acquisition and analysis.</p> <p>Methods</p> <p>In this study, left ventricular longitudinal systolic displacement was quantified in 57 patients (31 women and 26 men, 50 ± 16 years) using colour (colour TD) and spectral tissue Doppler (spectral TD) before and after temporal filtering (30 to 70 milliseconds in 20-millisecond steps) and changed offline gain saturation (0%, 50% and 100%), respectively. The results were compared with those obtained with anatomic M-mode.</p> <p>Results</p> <p>Whereas only minor differences occurred between the results of colour TD and anatomic M-mode measurements, spectral TD significantly overestimated the results obtained with both these methods. However, the limits of agreement between the results produced by all three studied methods were not clinically acceptable in any of the cases. The spectral TD displacement values increased along with increasing offline gain saturation whereas the effect of temporal filtering on colour Doppler measurements was insignificant.</p> <p>Conclusion</p> <p>Measurements of LV myocardial longitudinal displacement employing spectral TD, colour TD or anatomic M-mode produce different results, thus discouraging interchangeable use of these modalities. Whereas the results of spectral TD measurements can be significantly altered by changing offline gain setting, the effect of temporal filtering on colour TD measurements is insignificant, a fact that increases clinical practicality of the latter method.</p

Manual correction of semi-automatic three-dimensional echocardiography is needed for right ventricular assessment in adults; validation with cardiac magnetic resonance

Background: Three-dimensional echocardiography (3DE) and semi-automatic right ventricular delineation has been proposed as an appropriate method for right ventricle (RV) evaluation. We aimed to examine how manual correction of semi-automatic delineation influences the accuracy of 3DE for RV volumes and function in a clinical adult setting using cardiac magnetic resonance (CMR) as the reference method. We also examined the feasibility of RV visualization with 3DE. Methods: 62 non-selected patients were examined with 3DE (Sonos 7500 and iE33) and with CMR (1.5T). Endocardial RV contours of 3DE-images were semi-automatically assessed and manually corrected in all patients. End-diastolic (EDV), end-systolic (ESV) volumes, stroke volume (SV) and ejection fraction (EF) were computed. Results: 53 patients (85%) had 3DE-images feasible for examination. Correlation coefficients and Bland Altman biases between 3DE with manual correction and CMR were r = 0.78, -22 +/- 27 mL for EDV, r = 0.83, -7 +/- 16 mL for ESV, r = 0.60, -12 +/- 18 mL for SV and r = 0.60, -2 +/- 8% for EF (p < 0.001 for all r-values). Without manual correction r-values were 0.77, 0.77, 0.70 and 0.49 for EDV, ESV, SV and EF, respectively (p < 0.001 for all r-values) and biases were larger for EDV, SV and EF (-32 +/- 26 mL, -21 +/- 15 mL and -6 +/- 9%, p <= 0.01 for all) compared to manual correction. Conclusion: Manual correction of the 3DE semi-automatic RV delineation decreases the bias and is needed for acceptable clinical accuracy. 3DE is highly feasible for visualizing the RV in an adult clinical setting

Online) An Open Access

ABSTRACT Based on organizational assumptions, in order to be able to attain higher efficiency and meet the organization objectives, it is to recognize communicative features of individuals working for organization. The objective of this study was to investigate the relationship between communication skills with the effectiveness of physical education experts. The study is a descriptive and a survey research. The population considered for the current research study involves all 100 experts within the physical education and health department of the general Office of Education. All of these 100 people have been considered as the sample of this study. The tools for data collection include the questionnaire of communicative skills by Barton (1991) and the questionnaire of organizational efficiency by Hsu (2002) having the validity scores of 0.82 and 0.93, respectively. In order to analyze the collected data, descriptive and inferential statistical methods such as Pearson Correlation Coefficient and Multiple Regression Analysis have been applied. The results show that 56.7 percent of the participants are female and the remaining 43.3 percent are male. In addition, the findings reveal that among communication skills, audio/verbal sub-scale is the best predictor for the efficiency of male and female specialists. Furthermore, verbal communications has the highest simple correlation coefficient with organizational efficiency. Keywords: Communication Skills, Organizational Efficiency, Physical Education Experts INTRODUCTION In the value system of our society, sport is considered as a valuable sociocultural phenomenon and one of the major aspects of the society. Sport organizations as the executive custodians of the relationship between administrators and employees are considered among the important and influential areas of organizational interaction on production and human services within an organization. In this regard, the transfer of knowledge as the major objective of the organization requires a good and appropriate communication atmosphere among different administrative lavers. As a social being and in order to provide for different individual and social requirements and the attainment of organizational objectives, human beings need to establish relationship and interaction with other members within organizations and affect the. Interaction is a dynamic process that starts in itself and covers a considerable area in the world around us. Various models have been proposed related to the process of interaction that are in line with the development of models related to influential interaction and methods and techniques used to increase the influence on others and the attainment of personal and organizational objectives in order to increase the efficiency of an organization. Managers can facilitate the attainment of organizational objectives and a more effective management by taking into account effective communication networks and the improvement of human skills such as development and communication skills. Communication refers to the transfer of information from a sender to a receiver in such a way that it is understandable and clear for both parties. In case one of these elements (sender, receiver, the message) is missing, no communication would be don

Brain natriuretic peptide is related to diastolic dysfunction whereas urinary albumin excretion rate is related to left ventricular mass in asymptomatic type 2 diabetes patients

<p>Abstract</p> <p>Background</p> <p>The aims of this study were to estimate the prevalence of left ventricular systolic (LVSD) and diastolic (LVDD) dysfunction, and to test if BNP and urinary albumin excretion rate (AER) are related to LVSD, LVD and left ventricular mass (LVM) in asymptomatic type 2 diabetes patients.</p> <p>Methods</p> <p>Presence of LVSD, LVDD and LVM, determined with echocardiography, was related to levels of BNP and AER in 153 consecutive asymptomatic patients with type 2 diabetes.</p> <p>Results</p> <p>LVSD was present in 6.1% of patients whereas 49% (29% mild, 19% moderate and 0.7% severe) had LVDD and 9.4% had left ventricular hypertrophy. Increasing age (P < 0.0001) was the only independent variable related to mild LVDD whereas increasing BNP (P = 0.01), systolic blood pressure (P = 0.01), age (P = 0.003) and female gender (P = 0.04) were independent determinants of moderate to severe LVDD. AER (P = 0.003), age (P = 0.01) and male gender (P = 0.006) were directly and independently related to LVM.</p> <p>Conclusion</p> <p>About half of asymptomatic type 2 diabetes patients have LVDD. Of those, more than one third display moderate LVDD pattern paralleled by increases in BNP, suggesting markedly increased risk of heart failure, especially in females, whereas AER and male sex are related to LVM.</p

The effect of non-spherical platinum nanoparticle sizes on the performance and durability of proton exchange membrane fuel cells

Platinum (Pt) nanoparticles with different sizes of 2 nm and 5 nm supported on functionalized high surface area carbon (HSC) have been successfully synthesized with a one-pot synthesis technique in large scale. Of the interest for the proton exchange membrane fuel cell applications, the synthesized supported catalysts are evaluated by physical characterizations, half-cell and scaled up single cell tests to study the impact of the catalyst sizes on cell performance and durability. Physical characterizations clearly demonstrate the sizes, shapes, crystallinity phases, and the total loading of the Pt nanoparticles on HSC. Half cell characterizations demonstrate higher electrochemical surface area, higher mass activity, and less durability for the working electrode prepared by the smaller Pt nanoparticle sizes (2 nm) than the larger Pt nanoparticles (5 nm). Scaled up single cell tests using air and hydrogen as the cathode and anode reactants demonstrate the membrane electrode assembly (MEA) prepared by smaller Pt nanoparticle sizes (2 nm) shows the maximum power density of 1.1 W/cm2, which is 7% higher than the maximum power density of MEA prepared by larger Pt nanoparticles (5 nm) under similar operational conditions. The 30,000 cycles of accelerated stress test on the membrane electrode assembly prepared by larger Pt nanoparticles (5 nm) demonstrates 13% drop at maximum power density, illustrating the excellent performance against degradation (ageing).Canadian Urban Transit Research and Innovation Consortium || Natural Sciences and Engineering Research Council of Canad

A graphene-based microporous layer for proton exchange membrane fuel cells: Characterization and performance comparison

The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.renene.2018.03.065 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Water management is a critical issue for proton exchange membrane (PEM) fuel cells, and the use of a microporous layer (MPL) substantially improves the PEM fuel cell performance, reliability and durability through improved water management. In this study, graphene, technically a yet-to-be-developed category of material, is investigated as a potential MPL material, due to its high electrical and thermal conductivity. MPLs made of graphene (G-MPL) have been fabricated and assessed through morphological, microstructural, physical, and electrochemical characterizations and performance testing in a single scaled-up cell. Comparison is also made with MPLs made of a conventional material, Vulcan (V-MPL). The results show that the G-MPL has a unique morphology composed of horizontally packaged graphene flakes that improves water management, in-plane electrical conductivity (up to 2 times), catalyst activity, and platinum (Pt) utilization (up to 10%). The cell with the G-MPL has a better performance than the cell with the V-MPL under both fully (100% RH) and partially (40% RH) humidified conditions, with the peak power densities of 0.98 W cm−2 and 0.60 W cm−2, respectively – these peak power densities are about 7% and 43% higher than those obtained for the cell with the V-MPL at 100% and 40% RH, respectively.Ontario-China Research and Innovation Fund (OCRIF Round 3) Natural Sciences and Engineering Research Council of Canada (NSERC) via a Discovery Gran

Investigation Of Short-Side-Chain Ionomer And Membrane For Proton Exchange Membrane Fuel Cells

Paper presented at 2018 Canadian Society of Mechanical Engineers International Congress, 27-30 May 2018.Proton exchange membrane (PEM) fuel cells have been progressively designed to become suitable for high-temperature operation to achieve further performance improvements. However, the current state-of-the-art fuel cell materials, such as long-side-chain (LSC) ionomers and membranes, are not suitable for high-temperature operation, requiring development and investigation of alternative materials. In this study, short-side-chain (SSC) membrane and ionomer are considered as potential materials, and performance of a membrane-electrode assembly (MEA) manufactured with the SSC ionomer and membrane is experimentally investigated in a scaled-up fuel cell (45 cm2). Comparison is made with an MEA based on the LSC ionomer and membrane under identical preparation and testing conditions. The catalyst layers (CLs) made of either SSC or LSC ionomer are characterized through scanning electron microscopy (SEM) to understand their surface morphology and microstructure. Results show that the SSC ionomer embedded in the CL provides much more uniform surface morphology and well-proportioned microstructural characteristics than its LSC counterpart. Further, the MEA based on SSC ionomer and membrane demonstrates considerable performance superiorities under all the applied operating conditions. Furthermore, the performance of the MEA based on the SSC ionomer and membrane is found to be less sensitive to changes in operating conditions

A novel membrane electrode assembly design for proton exchange membrane fuel cells: Characterization and performance evaluation

The final publication is available at Elsevier via https://doi.org/10.1016/j.electacta.2019.01.064 © 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Conventional membrane-electrode assembly (MEA), a key component in proton exchange membrane fuel cells, only operates reasonably within a narrow range of operating conditions. In this study, a scaled-up MEA that can perform adequately under a wide range of humidification and flow conditions is developed. It consists of a microporous layer (MPL) composed of graphene for the cathode electrode, catalyst layers (CLs) prepared with a short-side-chain (SSC) ionomer, and a SSC electrolyte membrane. The results show that the graphene-based MPL employed on the cathode provides an excellent platform for the CL (hence promotes catalyst activity and catalyst utilization) and improves water retention, due to its unique microstructure and morphology. The proposed MEA provides stable and highly promising performance independent of flow conditions under the relative humidities (RHs) of 70% and 100%. Interestingly, the MEA also demonstrates relatively better cell performance under low-humidity conditions (40% RH), such that it performs noticeably better, as the reactants are supplied to the cell under low-flow condition, rather than moderate- and high-flow conditions.Ontario-China Research and Innovation FundNatural Sciences and Engineering Research Council of CanadaCatalysis Research for Polymer Electrolyte Fuel CellsAutomotive Partnership Canada [APCPJ 417858-11

Effect of Pt loading and catalyst type on the pore structure of porous electrodes in polymer electrolyte membrane (PEM) fuel cells

The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.energy.2018.02.134 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/Catalyst layer (CL) has a significant impact on the overall pore structure of the entire electrodes, thereby impacting the transport processes and the performance of polymer electrolyte membrane (PEM) fuel cells. In this study, the contribution of the CL to the entire electrode structure is experimentally investigated. The electrodes are prepared by using two types of catalysts with different platinum/carbon (Pt/C) ratios and Pt loadings and characterized by the method of standard porosimetry (MSP). The results show that for the same type of catalysts, as the Pt loading is increased, both the porosity and mean pore size of the electrode decrease, whereas the pore surface area increases. For a constant Pt loading, a lower Pt/C ratio results in a thicker electrode with a smaller porosity, smaller pore size, and larger pore surface area. The fractal dimension is found to be a good representative of the complexity of the pore structure of the electrode; a larger fractal dimension is detected for a higher Pt loading and a smaller Pt/C ratio.Ontario-China Research and Innovation Fund (OCRIF Round 3)Natural Sciences and Engineering Research Council of Canada (NSERC) via a Discovery GrantAutomotive Partnership Canada (APC), Natural Sciences and Engineering Research Council of Canada [Grant No. APCPJ 417858 - 11