The impact of the thermal treatment during ink preparation on the ionomer-supported catalyst interactions in the catalyst layers

Catalyst slurries (inks) were prepared with and without thermal treatment to determine the support/ionomer structures and interactions in the catalyst layer (CL) which impact on membrane electrode performance and durability. The thermal treatment of the ink has a nominal effect on the ionomer/support structure in which the carbon support is non-graphitised. The agglomerate/aggregate structures have a high degree of support/ionomer interface and sufficient macroporosity for water movement in the CL. This improves the membrane electrode assembly (MEA) performance, but also accelerates electrochemical carbon degradation. Thermal treatment of graphitised support-containing inks resulted in increased performance facilitated by a larger support/ionomer interface. Without thermal treatment, the more hydrophobic support would form aggregate structures in which water contact was restricted, limiting proton transfer, isolating catalyst, decreasing performance. The water limited access, would however, prolong stability during accelerates carbon degradation. The electrochemical properties were studied using full and half MEA cells.     

Effects of substrate concentrations on the growth of heterotrophic bacteria and algae in secondary facultative ponds

This paper presents the effect of substrate concentration on the growth of a mixed culture of algae and heterotrophic bacteria in secondary facultative ponds (SFPs) utilizing settled domestic sewage as a sole source of organic carbon. The growth of the mixed culture was studied at the concentrations ranging between 200 and 800 mg COD/l in a series of batch chemostat reactors. From the laboratory data, the specific growth rate (micro) was determined using the modified Gompertz model. The maximum specific growth rate ( micro(max)) and half saturation coefficients (K(s)) were calculated using the Monod kinetic equation. The maximum observed growth rate ( micro(max)) for heterotrophic bacteria was 3.8 day(-1) with K(s) of 200 mg COD/l. The micro(max) for algal biomass based on suspended volatile solids was 2.7 day(-1) with K(s) of 110 mg COD/l. The micro(max) of algae based on the chlorophyll-a was 3.5 day(-1) at K(s) of 50mg COD/l. The observed specific substrate removal by heterotrophic bacteria varied between the concentrations of substrate used and the average value was 0.82 (mg COD/mg biomass). The specific substrate utilization rate in the bioreactors was direct proportional to the specific growth rate. Hence, the determined Monod kinetic parameters are useful for the definition of the operation of SFPs.     

High temperature thermoelectric performance of p-type TaRhSn half Heusler compound: A computational assessment

Half Heusler compounds are gaining greater attractions as high temperature thermoelectric materials owing of their giant thermal power and promising thermoelectric performance. In the light of current study, we present a larger library having an overview of structural and physical details including electronic, mechanical, phonon and thermoelectric properties of TaRhSn material within the framework of the density functional theory and semi classical Boltzmann transport approach. The band structure calculations reveal the fact that TaRhSn is an indirect band gap semiconductor with energy gap of 1.25 eV. An in-depth insight on the thermoelectric properties such as the Seebeck coefficient, electrical conductivity, total thermal conductivity and figure of merit has been strictly put along with variation in temperature. The compound has the figure of merit with the maximum numeric value of 0.55 at 1100 K. The value of lattice thermal conductivity is found to be 19.4 W/mK at room temperature and shows a significant reduction in its value towards higher temperatures. These theoretical calculations have the capabilities to stimulate experimental research towards designing and improving the thermoelectric performance of TaRhSn based half Heusler compounds, thus permitting this compound as an efficient thermoelectric material at high temperatures.     

半速率优化策略研究

论述了使用半速率技术解决突发性话务量时可能碰到的一些问题,北京联通半速率信道的分配原则、使用策略及一些经验设置,以及结合网优支撑系统如何进行半速率策略的优化,同时,给出了北京联通半速率策略优化后的效果。     

Review of weld repair procedures for low alloy steels designed to minimise the risk of future cracking

Weld repairs to aged and degenerated materials are prone to early failure on return to service unless strict preparation and controlled welding procedures are followed. This paper reviews and appraises the practical weld repair procedures, which have been developed or are currently being considered, for low alloy ferritic steels used within the Power, Petrochemical and Refinery Industries. The half-bead and temper-bead approaches both manual and automatic are considered in detail. The alternative use of high nickel weld fills for repair welding of low alloy ferritic base materials are also considered. Some conclusions about the expected life of repair welds are drawn from recently sponsored projects.     

弹性约束半空间内浅埋圆孔对SH波的散射

利用复变函数法和多极坐标移动技术求解讨论弹性约束边界半空间内浅埋圆孔对稳态入射平面SH(shearing horizontal,反平面剪切)波的散射问题.为了克服直接构造波函数场的困难,采用一个半径很大的圆孔边界来拟合半空间的直边界,因而原来问题即转化为无限大空间内大圆孔和小圆孔对入射平面SH波的散射问题.文中具体讨论小圆孔边界处的动应力集中系数随无量纲波数、入射波入射角的变化情况,算例结果表明文中处理方法是合理的.     

电磁波的传播及其在介质表面上反射的动态模拟

电磁波的传播是电磁场理论的重要组成部分,本文以Visual Basic 6.0为平台,较详细地介绍了电磁波的传播、折射与反射(有效的反映了电场的半波损失)的动画制作过程.     

冻干麻疹活疫苗的热稳定性观察

对国产冻干麻疹活疫苗进行了加速热稳定性试验,结果在37℃、41℃及45℃的下降率分别为0.0245。0.0599及0.1 435 TCID_(50)/ml/天,三者差异十分显著;半衰期分别为12.3天。5.0天及2.1天,表明疫苗的稳定性有所提高,但与文献报道的差距尚大,比较不同基础滴度疫苗在37℃下的热稳定性,结果下降率及半衰期未见明显差异。     

Optimisation of digestion method for determination of arsenic in shrimp paste sample using atomic absorption spectrometry

The microwave digestion method was developed and verified for the determination of arsenic in shrimp paste samples. Experimental design for five factors (HNO₃ and H₂O₂ volumes, sample weight, microwave power and digestion time) were used for the optimisation of sample digestion. For this purpose, two level half factorial design, which involves 16 experiments, was adopted. The concentration of arsenic was analysed by graphite furnace atomic absorption spectrometry. Design Expert® 7.0 software was used to interpret all data obtained. The combination of 2 mL HNO₃ and 1 mL H₂O₂ volumes, 0.1 g sample weight, 1400 W power and 5 min digestion time was found to be the optimum parameters required to digest the shrimp paste samples. Tests with spiked samples presented good recoveries with relative standard deviations between 0.32% and 5.35%.