Hydrogen evolution during the oxidation of formaldehyde on Au:: The influence of single crystal structure and Tl-upd

Hydrogen evolution during formaldehyde oxidation in alkaline solution has been monitored by Differential Electrochemical Mass Spectrometry on Au(111) and polycrystalline gold. The current efficiency for hydrogen evolution increases with higher concentration and is in the same range on both, polycrystalline Au and Au(111) electrode. The onset potentials and half-wave potentials are higher on Au(111). Reaction orders for the faradaic current on the bare gold electrodes have been determined as 0.21 for higher and 0.76 for lower concentrations. Reaction orders for hydrogen evolution during formaldehyde oxidation are 1.4 times higher in each case. Tafel slopes in the range of 140-160 mV are found. This signifies that the first reaction step involving the formation of adsorbed hydrogen is largely determining the overall reaction rate. In the presence of thallium adlayers hydrogen evolution from formaldehyde oxidation is largely suppressed. On the thallium modified polycrystalline Au, formaldehyde oxidation is shifted for 100 mV to higher potentials where Tl is partially desorbed and hydroxide is coadsorbed on the modified surface. On thallium modified Au(111), a similar process takes place, but in the same potential region as the onset of formaldehyde oxidation on the bare surface and therefore the formaldehyde oxidation is only slightly shifted. Tafel slopes are decreased to 80 mV/dec in the presence of thallium. In the presence of adsorbed thallium, the first reaction step is in equilibrium, the coverage with adsorbed hydrogen is smaller and its recombination to H₂ is largely suppressed.     

碘溴化银T颗粒乳剂中碘的加入

高感光度乳剂制备中 ,如何利用好碘的掺杂技术 ,对于提高乳剂感光性能起至关重要的作用 ,本文针对碘溴化银T颗粒乳剂中不同的加碘方式、碘的不同分布及不同的加入量 ,对其晶型和感光性能的影响进行了综述。     

Humidity sensitivity of polypyrrole and polypyrrole/SBA‐15 host–guest composite materials

Polypyrrole (PPY) and PPY/SBA‐15 host–guest composite materials have been prepared using chemical synthesis route and characterized by XRD, IR, N₂ adsorption–desorption isotherms, and SEM. The humidity sensitive properties (HSP) of this kind of materials have been studied by analyzing the variation curve of impedance as a function of relative humidity. It was found that the PPY/SBA‐15 host–guest composites materials exhibit better HSP than that of the corresponding pure PPY. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3301–3305, 2006     

一种基于优先级表的实时调度方法

针对单处理器实时系统动态调度问题进行了研究,分析任务的到达时间、执行时间、截止时间和空闲时间等任务属性的敏感度和影响度,提出了一种基于优先级表的调度算法PTBM,使相对截止期越小、空闲时间越大的任务优先级越高。对关于实时任务属性敏感度和影响度的结论验证和与传统的EDF、LLF和PTD算法的对比进行仿真实验,仿真结果表明基于优先级表设计的实时调度算法PTBM具有较高的调度成功率。该方法可应用于实时系统的实时任务的动态调度中。     

含防爆剂农用硝酸铵的感度研究

实验在169℃左右加热硝酸铵到熔融状态,加入防爆剂,冷却到室温,得到含防爆剂的硝酸铵。测试其摩擦感度、5 s延滞期爆发点、静电火花感度以及配成铵油炸药后的撞击感度、雷管感度。结果表明,含防爆剂硝酸铵较普通硝酸铵撞击感度从88%降到24%,摩擦感度降为0%,5 s爆发延滞期从462℃增加到474℃,静电火花感度和雷管感度无明显变化。     

一种基于感声波纹结构的光学式声传感器

设计了一种基于硅MEMS敏感结构的光学式声传感器,其光学调制原理采用强度调制型,微敏感结构采用具有低应力波纹结构的感声薄膜芯片。对光纤与微敏感结构耦合技术进行实验研究,优化光学参数,并制作传感器样品。经实验测试,灵敏度达80mV/Pa。     

基于红外光声光谱的气体检测系统设计

随着工业现代化的发展,环境变化日益复杂,而人民的环境健康意识也在不断提高.在这种情况下,传统的气体检测系统已不能满足要求,有待开发一种高灵敏度、高分辨率的新型实时气体检测系统.从气体分子红外光谱理论出发,在对当前各种气体检测方法进行分析比较的基础上,设计了一种基于光声光谱技术的气体检测系统.实验证明：该系统可有效进行CO2气体检测.     

海洋非黏结柔性管道接头密封结构分析

介绍海洋非黏结柔性管道接头的常见密封结构,用Abaqus对接头的密封特性进行数值分析,研究密封圈的密封性能对不同密封结构参数的灵敏度,得到密封结构参数变化对接头密封结构的密封性能和力学性能影响的一般规律.结果表明密封结构的主要设计参数为密封圈的锥角和曲率半径以及加载位移等.     

平面线弹性问题的等几何形状优化方法

介绍具有等几何分析功能的GeoPDEs平台的数据结构和分析流程,针对二维平面形状优化问题,以控制顶点为设计变量,在推导出等几何分析的灵敏度计算公式后,提出基于GeoPDEs平台的灵敏度分析的高效实现方法,并采用移动渐近线法(Method of Moving Asymptotes,MMA)算法进行等几何形状优化.形状优化实例表明该方法收敛速度快,优化结果较理想.     

rGO-SnO2纳米复合物制备及室温下NH3气敏性能

采用沉淀-焙烧法制备了室温下对NH3具有高灵敏度和高选择性的rGO-SnO2纳米复合材料。利用X射线衍射（XRD），傅里叶红外光谱（FTIR），X射线光电子能谱（XPS），扫描电子显微镜（SEM），透射电子显微镜（TEM）和比表面积（BET）表征分析了纯SnO2与rGO(1.0%)-SnO2纳米复合物的属性。与纯SnO2相比，rGO(1.0%)-SnO2纳米复合物中SnO2晶体尺寸较小，约为6~20nm，比表面积更大，为33m2/g；rGO(1.0%)-SnO2纳米复合材料对0.01% NH3的灵敏度达到了49.6%，是相同NH3浓度下纯SnO2灵敏度的2.1倍，并且响应和恢复时间分别为21s和204s，比纯SnO2缩短了24s和10s，具有良好的重复性，选择性与稳定性；rGO(1.0%)-SnO2纳米复合材料优良的气敏性能是由rGO与SnO2产生的p-n异质结以及溶解的NH3电离出导电离子共同作用的结果。