Iron porphyrin-based cathode catalysts for PEM fuel cells: Influence of pyrolysis gas on activity and stability

Fe-based catalysts for the O₂ reduction in acidic medium were prepared by impregnating chloro-iron tetramethoxyphenylporphyrin (Cl-FeTMPP) on a non-microporous carbon black and heat-treating the resulting material at 950 °C either in NH₃ (Mode 1) or in Ar (Mode 2). The most active catalyst using Mode 1 has a Fe bulk content of 0.4 wt% and an activity of 17 mA mg⁻¹ at 0.8 V in fuel cell. This activity is controlled by the microporous surface area of the catalyst. The most active catalysts using Mode 2 has an Fe bulk content of 3.7 wt% and an activity of 1.9 mA mg⁻¹ at 0.8 V in fuel cell. In Mode 2, the nitrogen and/or the iron surface concentrations control the activity. Concerning stability, Mode 1-catalysts are unstable while Mode 2-catalysts show stability for at least 15 h when at least 66 wt% Cl-FeTMPP is impregnated onto N330 and heat-treated at 950 °C in Ar. The catalyst made with 66 wt% Cl-FeTMPP has a bulk Fe content of 5.2 wt% and an activity of 1.3 mA mg⁻¹ at 0.8 V in fuel cell. Thus, in the present study, pyrolysis in NH₃ gives active but unstable catalysts while pyrolysis in argon gives less active but more stable catalysts at high Cl-FeTMPP loading. Graphitization of Cl-FeTMPP during pyrolysis in argon seems to impart stability. Mode 2-catalysts are stable in spite of a high peroxide yield of 26% while Mode 1-catalysts are unstable in spite of a low 5% peroxide yield.     

Review of Intercultural counselling and assessment: Global perspectives.

Reviews the book, Intercultural Counselling and Assessment: Global Perspectives edited by Ronald J. Samuda and Aaron Wolfgang (1985). Intercultural Counselling and Assessment is an edited volume of papers presented to an invited Symposium on Intercultural Counselling held at Queen's University at Kingston, Ontario, 1983. The intention of the publication, as stated by the editors, was to fill the gap in guidelines and methods in intercultural counselling by providing source material that is both theoretical and practical. The book is geared to professionals in the field of education, psychology, and social work, with the goal of engendering "greater sensitivity and a more professional approach to the task of coping with an increasingly varied and mixed population of students in schools" (p. xvii). The strength of the book lies in its comprehensive coverage. The philosophy of counselling conveyed in the book reflects the orientation of multiculturalism in Canadian immigration policy. Six chapters address the issues and answers in counselling specific ethnic and cultural groups, including Chinese immigrants, South Asian immigrants, West Indian immigrants, European immigrants, Native Canadians, and foreign students. Another six chapters provide the background and guidelines for counselling minorities in specific environments, such as in employment, correctional service, disability service, and education. It is a comprehensive volume and has highlighted the important issues that counsellors should become familiar with in an intercultural society. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

主板行情

2006年8月8日，下午5点30分，华硕电脑（Asustek）与技嘉科技（Gigabyte）在台湾证券交易所共同发表声明，技嘉科技将切割自有品牌主板及显卡产品的相关资产与营业，与华硕电脑合资成立新公司。两大知名品牌的合并对于主板与显卡业界而言是巨大的震动，但是具体价格反应还要等到下月才能有所体现。     

Co-Administration of Simvastatin Does Not Potentiate the Benefit of Gene Therapy in the mdx Mouse Model for Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is the most common and cureless muscle pediatric genetic disease, which is caused by the lack or the drastically reduced expression of dystrophin. Experimental therapeutic approaches for DMD have been mainly focused in recent years on attempts to restore the expression of dystrophin. While significant progress was achieved, the therapeutic benefit of treated patients is still unsatisfactory. Efficiency in gene therapy for DMD is hampered not only by incompletely resolved technical issues, but likely also due to the progressive nature of DMD. It is indeed suspected that some of the secondary pathologies, which are evolving over time in DMD patients, are not fully corrected by the restoration of dystrophin expression. We recently identified perturbations of the mevalonate pathway and of cholesterol metabolism in DMD patients. Taking advantage of the mdx model for DMD, we then demonstrated that some of these perturbations are improved by treatment with the cholesterol-lowering drug, simvastatin. In the present investigation, we tested whether the combination of the restoration of dystrophin expression with simvastatin treatment could have an additive beneficial effect in the mdx model. We confirmed the positive effects of microdystrophin, and of simvastatin, when administrated separately, but detected no additive effect by their combination. Thus, the present study does not support an additive beneficial effect by combining dystrophin restoration with a metabolic normalization by simvastatin.     

滤波器技术简要回顾

开关电容滤波器技术允许使用片外或片内时钟调整滤波器截止频率,时钟频率是截止频率的倍数.这个本来非常方便的特性,却总是被这类滤波器的"采样数据"的本质弄得不方便.即这种技术总需要一个时钟,一个在纯模拟电路中的数字部分.     

Reclaiming the energy of a schedule: models and algorithms

We consider a task graph to be executed on a set of processors. We assume that the mapping is given, say by an ordered list of tasks to execute on each processor, and we aim at optimizing the energy consumption while enforcing a prescribed bound on the execution time. Although it is not possible to change the allocation of a task, it is possible to change its speed. Rather than using a local approach such as backfilling, we consider the problem as a whole and study the impact of several speed variation models on its complexity. For continuous speeds, we give a closed‐form formula for trees and series–parallel graphs, and we cast the problem into a geometric programming problem for general directed acyclic graphs. We show that the classical dynamic voltage and frequency scaling (DVFS) model with discrete modes leads to an NP‐complete problem, even if the modes are regularly distributed (an important particular case in practice, which we analyze as the incremental model). On the contrary, the Vdd‐hopping model that allows to switch between different supply voltages (V_DD) while executing a task leads to a polynomial solution. Finally, we provide an approximation algorithm for the incremental model, which we extend for the general DVFS model. Copyright © 2012 John Wiley & Sons, Ltd.     

Efficacy of zinc salts to protect glass against atmospheric alteration. Part II: Possible passivation mechanisms

To investigate the origin of the protection effect of zinc salts against glass atmospheric alteration, the speciation of Zn²⁺ ions on glass according to the deposit protocol and the Zn²⁺ surface concentration, and its change over time, was investigated in the light of the respective performances of the treatments. In that respect, a combination of various characterization methods of the glass surface and near-surface was used before and after aging experiments (temperature, relative humidity (RH) control) of the Zn-treated glass. Different Zn-species could be observed on the surface of the treated glass: chemisorbed species, physisorbed species and precipitated hydroxide phases, their respective distribution being highly dependent on the nature of the treatment and on the Zn²⁺ surface concentration. GI-XAS (Zn K-edge) and ToF-SIMS experiments pointed out the conversion by thermal activation of these surface species into chemisorbed species inserted in the glass network in the near-surface. The chemisorbed species appear to be the most effective ones for the glass protection, possibly by making the surface less soluble, less hydrophilic and even by acting as a diffusion barrier.     

Monitoring of the discoloration on γ‐irradiated PE and EVA films to evaluate antioxidant stability

γ‐Irradiated films could provoke unexpected interaction with proteins for instance just after irradiation and not necessarily after 12 months indicating there is no more reactive species. The optical properties of two multilayer films [polyethylene (PE)/ethylene vinyl alcohol (EVOH)/PE and ethylene vinyl acetate (EVA)/EVOH/EVA] after different γ‐irradiation doses is then studied in this work. The investigation on these films, either non‐irradiated or γ‐irradiated (up to 270 kGy), is performed by colorimetry measurement over time (up to 12 months) to assess the generation of new species inside the materials. The color change is directly correlated with absorbed γ‐doses. Over time, the color decreases and goes back to its initial time level. This discoloration evolution could be therefore used as an indication of the completion of the generated species reactions induced by γ‐irradiation. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46114.     

Diffusion along grain and interphase boundaries in alpha Zr and Zr-2.5 wt pct Nb alloy

Diffusion parameters of Cr diffusion along the α/β interphase boundaries of a Zr-2.5 wt pct Nb alloy are presented. The conventional radiotracer technique combined with serial sectioning of the samples was applied. In the Arrhenius plot, it is possible to consider only one straight line (with Q=133 kJ/mol for 615<T<953 K) or two zones (with Q=230 kJ/mol for 773<T<953 K and Q=77 kJ/mol for 615<T<773 K). An analysis is made of these results together with previous data concerning diffusion along short circuits paths in α-Zr (grain boundaries) and Zr-2.5 wt pct Nb (interphase boundaries): Zr and Nb as the alloy component elements and Ni, Fe, and Co as other relevant impurities. Different mechanisms are proposed: a vacancy mechanism for Zr and Nb and an interstitial-like mechanism for the impurities, for both kind of boundaries. The influence on diffusion and the estimated values of the impurities segregation in the α phase are discussed in the work. This article is based on a presentation made in the symposium entitled “Defect Properties and Mechanical Behavior of HCP Metals and Alloys” at the TMS Annual Meeting February 11–15, 2001, in New Orleans, Louisiana, under the auspices of the following ASM committees: Materials Science Critical Technology Sector, Structural Materials Division, Electronic, Magnetic & Photonic Materials Division, Chemistry & Physics of Materials Committee, Joint Nuclear Materials Committee, and Titanium Committee.     

Psychological Assessment in Asia: Introduction to the Special Section.

Psychological assessment with Asians is an important topic not only for psychologists from Asian countries but also for psychologists in multicultural societies with large populations of ethnic Asians. There is a dearth of information in the English language literature on psychological assessment for Asians. This special section is organized to review various forms of psychological assessment in Asia. The objectives of the special section are to inform test users and researchers of the issues related to cross-cultural validity of psychological assessment in Asia and to introduce examples of adapted and indigenously developed instruments that are culturally appropriate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)