Electron cryo-microscopy of biological specimens on conductive titanium-silicon metal glass films

Thin films of the metal glass Ti88Si12 were produced by evaporation and characterized by AFM and conductivity measurements. Thin Ti88Si12 support films for electron microscopy were prepared by coating standard EM grids with evaporated films floated off mica, and characterized by electron imaging and electron diffraction. At room temperature, the specific resistance of a thin TiSi film was 10(6) times lower than that of an amorphous carbon film. At 77K, the specific resistance of TiSi films decreased, whereas that of carbon became immeasurably high. The effective scattering cross-section of TiSi and amorphous carbon for 120 kV electrons is roughly equal, but TiSi films for routine use can be approximately 10 times thinner due to their high mechanical strength, so that they would contribute less background noise to the image. Electron diffraction of purple membrane on a TiSi substrate confirmed that the support film was amorphous, and indicated that the high-resolution order of the biological sample was preserved. Electron micrographs of TiSi films tilted by 45 degrees relative to the electron beam recorded at approximately 4 K indicated that the incidence of beam-induced movements was reduced by 50% compared to amorphous carbon film under the same conditions. The success rate of recording high-resolution images of purple membranes on TiSi films was close to 100%. We conclude that TiSi support films are ideal for high-resolution electron cryo-microscopy (cryo-EM) of biological specimens, as they reduce beam-induced movement significantly, due to their high electrical conductivity at low temperature and their favorable mechanical properties.     

Feedstock powder processing research needs for additive manufacturing development

Additive manufacturing (AM) promises to redesign traditional manufacturing by enabling the ultimate in agility for rapid component design changes in commercial products and for fabricating complex integrated parts. By significantly increasing quality and yield of metallic alloy powders, the pace for design, development, and deployment of the most promising AM approaches can be greatly accelerated, resulting in rapid commercialization of these advanced manufacturing methods. By successful completion of a critical suite of processing research tasks that are intended to greatly enhance gas atomized powder quality and the precision and efficiency of powder production, researchers can help promote continued rapid growth of AM. Other powder-based or spray-based advanced manufacturing methods could also benefit from these research outcomes, promoting the next wave of sustainable manufacturing technologies for conventional and advanced materials.     

CHV190系列变频器在永磁同步电机驱动矿井提升机中的应用

本文分析了矿井提升机的运行特点,详细阐述了英威腾CHV190系列起重提升专用变频器用于永磁同步电动机驱动的节能型矿井提升机的选型配置原则,最后介绍了应用现场的调试步骤及注意事项。     

Towards a GC-based microsystem for benzene and 1,3 butadiene detection: Pre-concentrator characterization

The performance of a gas pre-concentrator/gas chromatographic column/gas sensor system was studied step by step towards benzene vapor in presence of 1,3 butadiene vapor. The pre-concentrator, based on an activated carbon of high adsorption capacity, was first characterized using a GC/FID system. By this way, the adsorption capacity of each pollutant was evaluated, first separately, then mixed with different proportions in air. It was shown that the affinity of the pre-concentrator for benzene was higher than for butadiene. Once the optimal pre-concentration parameters were adjusted, we replaced the FID detector by a metal oxide gas sensor. The use of such gas pre-concentrator allowed decreasing the detection limit of the system towards benzene in presence of butadiene by at least ten times.     

Solar or surplus heat-driven actuators using metal hydride alloys

A metal hydride (MH) actuator provides mechanical work by applying the hydrogen pressure transition that originates from the reversible reaction of the MH alloy as it absorbs and desorbs hydrogen gas. The MH actuators that have been reported employ a Peltier element or an electrical heating resistance wire as a heat source. This paper describes the design of an MH actuator that is driven by low-quality heat sources, such as solar heat or surplus heat. A certain composition of a LaNi₅-based alloy that produces desorbing and absorbing reactions through a low-temperature difference is specified. This alloy composition can provide a large amount of hydrogen desorption using solar heat or surplus heated water and a large amount of hydrogen absorption by natural air cooling in an adequate reaction time. To improve the moving speed and to control the performance, a reciprocating air compressor that applies this solar or surplus heat-driven MH actuator is proposed. These findings support the efficacy of an MH actuator operating without electric or fossil fuel energy consumption.     

Effect of micro-electrode geometry on NO2 gas-sensing characteristics of one-dimensional tin dioxide nanostructure microsensors

Electrodes with micro-gaps are fabricated by using dc-sputtering and FIB techniques. SnO₂ nanowires are deposited on the micro-gap (1-30 μm) by suspension dropping method to fabricate a micro-gas sensor. The sensing ability of various SnO₂ micro-gap sensors is measured. A comparison between sensors reveals that the short-gap electrode has numerous advantages in terms of reliability, high sensitivity and detection of low concentrations of NO₂, while the large-gap electrode is relatively sensitive for high concentrations. Conductance measurements are carried out at different surface temperatures and NO₂ concentrations in order to investigate the effects that the gap size has on the overall sensor conductance. The results suggest that the interface between the electrode and sensitive layer has a very important role for the sensing mechanism of tin dioxide gas sensors.     

基于自动调焦的微机控制显微硬度计

传统显微硬度计自动化程序不高,难以满足现代信息处理与分析要求,本文提出的基于自动调焦的微机控制技术应用传统显微硬度计中,能对各种金相试样进行自动测试,实践中取得了很好的效果。     

A sensitivity analysis of powder forging processes

The purpose of this paper is to analyze the sensitivity problems in metal forming of rigid-visco-poroplastic materials. A repressing powder forging process is analyzed. Parameter sensitivity, material derivative, and control volume approaches to shape sensitivity analysis are presented, analyzed, and compared. Discretization of the continuum expressions is presented. The numerical solutions for parameter sensitivity in forging problems have been described. Numerical examples concerning simple compression test of cylindrical porous specimen are presented.     

KJ2005煤井监控系统软件的设计与实现*

针对目前中小型煤井的需求,结合计算机技术和网络技术,采用模块化设计在VC++ 6.0下开发了KJ2005煤井监控系统。对该软件的主要模块进行了简单介绍,并详细介绍了其串口通信接口程序的设计,给出了部分通信源码。应用表明,该系统简单、实用,能及时为用户提供准确信息,能动地减少了事故发生。     

原子吸收光谱法快速测定松香皂中几种金属元素

提出了用原子吸收光谱法快速测定松香皂中几种金属元素的方法。考察了元素干扰情况及灰化温度。该方法快速、简便、准确 ,RSD为 0 .95 %～ 2 .2 1% ,回收率为 95 .6 %～ 10 8.7%。