Hydrogen electrosorption into Pd-Pt-Au ternary alloys

Thin layers of Pd-Pt-Au alloys were prepared by metal codeposition at constant potential from chloride solutions. The process of hydrogen electrosorption into Pd-Pt-Au alloys was investigated in acidic solution (0.5 M H₂SO₄) using cyclic voltammetry and chronoamperometry, also coupled with the electrochemical quartz crystal microbalance. It was found that Pd alloying with both Pt and Au decreases the maximum hydrogen solubility, but improves the kinetics of absorbed hydrogen oxidation, which is mirrored in a negative shift of the potential of hydrogen desorption peak and shorter hydrogen desorption time. In Pd-Pt-Au alloys the effect of absorption/desorption hysteresis and the stresses connected with hydrogen absorption are reduced in comparison with pure Pd. After prior hydrogen absorption in Pd-Pt-Au alloys, surface oxides are formed and reduced at potentials even by 200 mV lower than before hydrogen treatment.     

Nanocomposite polymer layers for molecular tribology

We discuss a novel strategy for the formation of elastomeric boundary lubrication coatings from block copolymers grafted to a reactive interface of a silicon substrate. We demonstrate molecularly thick thermoplastic elastomeric films with promising microtribological properties. These films are composed of an elastomeric rubber phase reinforced by the net of glassy nanodomains. These elastomeric layers are extremely wear resistant under shear stresses due to the unique combination of a chemically grafted elastic matrix capable of tremendous reversible deformation (500–1000%) stabilized by a chemically interconnected nanodomain net.     

Ionic conductivity improvement in primary pores of fuel cell catalyst layers: Electropolymerization of m-aminobenzenesulfonic acid and its effect on the performance

Catalyst layers of direct methanol fuel cells (DMFCs) are modified by in situ electropolymerization of m-aminobenzenesulfonic acid. By using electrochemical impedance spectroscopy and porosimetry, this modification is found to add polymer electrolyte into primary pores (<10 nm), where ionic resistance is high for lack of polymer electrolyte (i.e., Nafion), and the additional electrolyte successfully decreases the ionic resistance by 10-15% compared to the plain carbon surface with a slight ion-conductivity (>40 kΩ cm). In view of methanol oxidation characteristics, this modification decreases the resistance by ca. 25% (from 5.1 Ω cm² to 3.7 Ω cm²) at 0.6 V vs. DHE, resulting in the increase in the cell voltage of DMFC test by ca. 20 mV. The clear relation between the performance and the microstructures is concluded to be helpful to understand the performance of fuel cell electrodes in detail.     

求解多层壁温度场的温度响应方法

本文给出一种首先利用Laplace变换求解在单位脉冲作用下多层壁表面的热流响应函数,然后利用求解导热反问题的解析公式求解出多层壁各层中的温度响应函数.对任意温度扰量作用在多层壁的边界条件下,利用了关于线性系统的DuhameI积分原理求解整个多层壁的温度场.两个计算实例说明了这种方法是极为有效的.     

VLAN在医院网络中的应用

随着医院信息数字化进程的快速发展,计算机应用的广泛,对于信息通道的网络的要求也越来越高。本文介绍分析了本院应用虚拟局域网(VirtualLocalAreaNetwork,简称VLAN)的一些规划、配置等内容。     

江汉油区盐间非砂岩油层酸化增产效果分析

江汉油区盐间非砂岩油藏具有较大的增产潜力,但产量递减快,容易导致油井近井地带碳酸盐结垢。为了提高增产效果,必须认识分析盐间非砂岩酸化机理,对盐间非砂岩油层酸化工艺、施工工艺进行改进。     

Photostability of liquid crystals and alignment layers

Abstract— Photostability of liquid‐crystal (LC) materials and surface alignment layers was evaluated using a UV lamp and a blue laser beam. Both organic polyimide (PI) and inorganic silicon‐dioxide (SiO₂) alignment layers were studied under nitrogen environment. Two commercial TFT‐grade LC mixtures (low‐birefringence MLC‐9200‐000 and high‐birefringence TL‐216) were used for comparisons. Results indicate that SiO₂ alignment layers are much more robust than PI layers, and low birefringence LCs are more stable than the high‐birefringence ones. At the He‐Cd laser wavelength (λ = 442 nm), both LC mixtures and SiO₂ alignment layers are hardly damaged. To lengthen the lifetime of an LCD projector, inorganic SiO₂ alignment layers, high‐optical‐density UV filter, long cutoff‐wavelength blue filter, and short‐conjugation (low birefringence) LC materials should be considered.     

安徽怀宁古变质核杂岩体的结构及构造演化

变质核杂岩体是区域性伸展构造的主要类型之一。安徽怀宁即是这种构造在大陆板块内部发育并得到保存的典型地区。通过区域大比例尺构造解析认为:怀宁古变质核杂岩体自下而上由变质核、基底剥离断层、褶叠层及盖层4个部分组成。其经历了2次伸展体制及2次收缩体制的构造叠加,形成了一个多期复合变形变质的古变质核杂岩体。     

The influence of oxide surface layers on bulk electron probe microanalysis of oxygen—application to Ti-Si-O compounds

This paper discusses a generalized method to measure with the electron probe microanalyzer (EPMA) the oxygen in a material containing a surface oxide layer. The continuum background is the most difficult to measure, particularly for materials in which oxygen-free samples cannot be produced. The method depends on the preparation of either oxygen-free samples or well characterized oxygen-containing samples. Specific application of the method to the Ti-Si-O system is discussed. In addition, measurements of oxide surface-layer thickness of 3.6–8.0 nm on Ti and Ti-Si compounds were obtained using EPMA and a scanning Auger microprobe (SAM). The nature of the oxide surface layers was shown using x-ray photoelectron spectroscopy (XPS).     

The growth of buffered GaAs mesfet structures by LPE

Layers of LPE GaAs have been grown with background carrier levels in the low 10¹⁴ cm⁻³ range by systematic bakeouts of the Ga melts together with between-run loading in a dry N₂ environment. High resistivity layers in the range 10₃-10⁴Ω cm have been grown by making use of the compensation of free carriers by the out diffusion of Cr from the substrate. Intentional Cr-doping from the melt resulted in layers with poor surface morphologies. Buffered MESFET structures have been grown which show near ideal carrier concentration profiles and which do not exhibit interfacial space charge effects.