Study of the effect of noble metal promotion in Ni-based catalyst for the Sabatier reaction

This paper reports the preparation and the evaluation of the performance of Ni-based powder catalysts with low nickel loading on the CO2 methanation reaction, that is an integral part of the power-to-gas (PtG) technology. CeO₂, CeZrO₄ and CeO₂/SiO₂ were selected as possible supports, and the results of this first screening pointed out that 10%Ni/CeO₂ catalyst could offer the best reaction performances because of ceria's peculiar characteristics. Moreover, the promotion of this promising formulation with the addition of a small amount of noble metals (Pt, Ru, Rh) was investigated, showing that platinum in particular can enhance the catalyst performances. A further study related to the noble metal loading pointed out that platinum and ruthenium have a different optimum loading condition: this result, together with the activity tests performed on monometallic formulations with only the noble metal, suggested that the two metals are able to catalyse two different reactions, thus promoting two different reaction mechanisms.     

变截面Euler-Bernoulli梁在轴力作用下固有振动的级数解

建立了截面特性、轴力和质量分布均连续变化的Euler-Bernoulli梁固有振动方程。采用Frobeniu方法求解方程,得到了方程的级数解析解;并计算了结构的振动频率与振型。算例证明了该方法的有效性,并表明轴向力的几何非线性效应对振动的低阶频率和自振振型有一定的影响,级数项数的取值对算法的收敛性有影响。     

A rapid h.p.l.c. method for the determination of methionine hydroxy analogue free acid in supplemented feeds

Two methods are described for determining methionine hydroxy analogue free acid (HMB) in supplemented poultry feeds. The procedure is based on extraction of analogue from the feed, followed by high-pressure liquid chromatographic measurement of the HMB directly after extraction or, more rigorously, after extraction and hydrolysis of oligomers to monomer. Recoveries of HMB over the supplementation range 0.08–0.25% (by wt) are 98% with coefficients of variation of 5.4% in commercial poultry feeds. A 98% correlation coefficient is obtained when the analyses are compared with the gas chromatographic method.     

Effects of nimesulide on constitutive and inducible prostanoid biosynthesis in human beings

BACKGROUND: The aim of this study was to test the hypothesis that nimesulide, a nonsteroidal antiinflammatory drug, or its principal metabolite 4-hydroxynimesulide, is a selective inhibitor of prostaglandin H synthase-2 in human beings. METHODS: Heparinized whole blood samples obtained from healthy subjects were incubated with lipopolysaccharide (10 micrograms/ml) for 24 hours at 37 degrees C and prostaglandin E2 was measured in plasma as an index of monocyte prostaglandin H synthase-2 activity. The production of thromboxane B2 in whole blood allowed to clot at 37 degrees C for 60 minutes was assessed as an index of platelet prostaglandin H synthase-1 activity. We also measured the urinary excretion of 11-dehydrothromboxane B2, prostaglandin E2, 6-ketoprostaglandin F1 alpha, and thromboxane B2 as in vivo indexes of cyclooxygenase activity. All prostanoids were measured by previously validated radioimmunoassay techniques. RESULTS: In the whole blood assays in vitro, nimesulide was twentyfold more potent than 4-hydroxynimesulide toward the two isozymes and both compounds displayed a twentyfold preference for prostaglandin H synthase-2 versus prostaglandin H synthase-1. The administration of a single oral dose of 100 mg nimesulide to six healthy subjects significantly (p < 0.01) reduced monocyte prostaglandin H synthase-2 and prostaglandin H synthase-1 activity ex vivo by more than 90% and 50%, respectively, up to 6 hours. At 24 hours, prostaglandin H synthase-2 but not prostaglandin H synthase-1 activity was significantly reduced by 49% (p < 0.05). Nimesulide significantly (p < 0.05) reduced the urinary excretion of 11-dehydrothromboxane B2 and 6-ketoprostaglandin F1 alpha by approximately 30% and 25%, respectively, while not affecting that of prostaglandin E2 and thromboxane B2. CONCLUSIONS: Nimesulide is a potent inhibitor of human monocyte prostaglandin H synthase-2. However, despite a twentyfold selectivity ratio, therapeutic plasma levels of nimesulide are sufficiently high to cause detectable inhibition of platelet prostaglandin H synthase-1.     

基于ANSYS的渐进结构拓扑优化方法比较

以大型有限元通用软件ANSYS作为平台进行二次开发,探索基于渐进结构优化方法的结构拓扑优化途径.通过直接删除单元和运用单元生死技术,发展了两种实现结构拓扑优化的途径,并与ANSYS自带的结构拓扑优化功能进行比较研究.结果表明,直接删除法和单元生死法均可用于工程实际,运用单元生死技术进行基于ESO的结构拓扑优化有更大的灵活性和实用性.     

高速铁路中承式钢箱混凝土系杆梁拱组合桥极限承载能力分析

采用有限元方法,结合高速铁路中某特大中承式钢箱混凝土系杆梁拱组合桥工程实际,建立了该组合体系桥梁的全桥有限元模型,进行了桥梁整体结构极限承载能力分析。分析过程中主要考虑了材料非线性、几何非线性、施工制造误差、荷载效应、钢与混凝土的组合效应等对桥梁极限承载能力的影响。研究结果表明,主拱肋、主纵梁及横梁固结形式的中承式钢箱混凝土系杆拱梁组合体系具有刚度大、承载能力高、美观经济等特点,在铁路尤其是高速铁路建设中具有良好的应用前景。所得结论对今后同类桥梁设计和分析具有指导意义。     

Pacific Tracker 2 – Expert System (PacTrac2-ES) behavioural assessment and intervention tool for the Pacific Kids DASH for Health (PacDASH) study

The Pacific Tracker (PacTrac) is a computer program designed to analyse food intakes of individuals from the Pacific Region. PacTrac’s original output included servings of daily intake of food groups according to the United States Food Guide Pyramid, nutrient intake recommendations, and a comparison to other national nutrition recommendations. PacTrac was made available for public use through the Hawaii Foods website (hawaiifoods.hawaii.edu). PacTrac2 is an updated and expanded version of PacTrac that uses the United States MyPyramid/MyPlate food groups in household units of daily intake, rather than servings. In addition, the PacTrac2 includes a physical activity analysis tool which quantifies minutes of physical activities and their intensities based on energy estimates from the compendium of physical activity and research on children. An Expert System (ES) – a computerised decision tree to guide behaviour change – was developed using information on self-efficacy and stage of readiness to change, and the fruit and vegetable intake and physical activity information from PacTrac2. The ES produces reports for the child, the parent/guardian, and the child’s physician with child-specific strategies, targeted behavioural information, and feedback tailored to the child. PacTrac2-ES was designed for the Pacific Kids DASH for Health (PacDASH) intervention study, conducted in the Kaiser Permanente health care system in Hawaii. The intervention is based on the child’s self-efficacy and stage of readiness to change intake of fruits and vegetables and physical activity, with a goal of maintaining body weight to prevent obesity. The intervention is complemented with stage-based mailers addressing the environment for physical activity and fruit and vegetable intake and newsletters that address related behaviours (sedentary activity and a DASH eating approach). This project is the first to expand the PacTrac to contain children’s foods and physical activities from the Pacific Region and to use current US MyPyramid/MyPlate food and physical activity analysis and guidance systems, and to develop and implement an Expert System for fruits, vegetables and physical activity of 5–8-year-old children. The PacTrac2-ES was used in the PacDASH study and will be used for other programs to promote healthy eating and physical activity of children in the Pacific Region.     

Study of phenolic resin and their tendency for carbon graphitization

Phenolic resins are important materials in various application sectors due to their outstanding mechanical and thermal properties. However, phenolic resins are known as typical non-graphitized carbon precursor. In this work, important parameters related to the synthesis of PRs were studied: the concentration of the catalyst and the molar ratio between phenol and formaldehyde. The structural information was performed by Fourier Transformation Infrared Spectroscopy and solid state nuclear magnetic resonance of carbon analysis to define mainly between novolac or resol resin. The thermal characteristics of the resins were studied for TGA and their tendencies for graphitization were verified by powder x-ray diffraction and Raman spectroscopy and SEM/HRTEM analysis. As a conclusion, it was verified that the phenolic resins prepared with excess of formaldehyde in acidic medium can present different properties according to their composition, which allows for qualifying them as potential materials for different applications in the technological area that involves graphitized carbon.     

钢—混凝土组合结构中剪力连接件承载力的比较

随着建筑技术的发展，钢—混凝土组合结构应用得越来越多，而剪力连接件是这类结构的关键部位，对其计算显得尤为重要。本文比较了钢—混凝土组合结构中几种常用的剪力连接件，分析了它们的抗剪强度和疲劳抗力，比较了不同国家或研究者给出的计算公式之间的差异，最后得到了几点有用的结论。