A procedure for increasing the contrast of biological specimens in edge-projection TEM

Rotary shadowing has been used to increase the image contrast of biological specimens during edge-projection imaging in the transmission electron microscope (TEM). In this imaging mode, biological specimens are adsorbed from aqueous solution onto a highly curved substrate and observed in a direction parallel to its surface. High contrast TEM images are obtained at 200 kV when a 1–3 nm layer of tungsten is thermally evaporated onto the substrate at an angle of about 9°. Individual adsorbates are clearly delineated by the smooth, continuous, and fine-grained tungsten layer that surrounds them. TEM images obtained with this technique can provide a unique view of biological adsorbates on metal, insulator or semiconductor substrates.     

Method for localization of sialic acid on cell surface and cell interior in peripheral blood: a pilot study

This article presents a method for identification and localization of cell surface and intracellular sialoglycoconjugates of peripheral blood cells. To reveal cell surface conjugates, a sample of peripheral blood was incubated with lectin after centrifugation and rinsing. For intracellular localization in leukocytes, RBCs were lysed and the membranes were permeabilized prior to cytochemical reaction. Fluorescein isothiocyanate conjugated lectins were used for visualization in fluorescence microscope. All lectins bound specifically to the surface of erythrocytes. Confocal microscopy showed surface and intracellular labeling of permeabilized leukocytes. A part of the signal in eosinophils originated from binding of anionic fluorophore to cationic granular proteins.     

基于响应曲面法的溅射沉积薄膜工艺参数优化

为了研制出适用于高温等恶劣环境且性能优良的用于切削力测量的合金薄膜传感器,结合新型合金薄膜材料的基本性能和离子束、磁控溅射技术,研究了新型薄膜传感器的制作工艺,建立了影响薄膜溅射速率的试验分析模型,研究了氩气流量、氩气工作压强及溅射功率三个因素对薄膜溅射速率的影响,应用响应曲面法对模型进行了优化,并运用方差分析检验了该预测模型的拟合度,建立了溅射速率的等值线和响应面,从而确定了各因素的最佳水平范围,实现了工艺参数的优化。     

基于满应力准则的薄板结构加强筋的设计法

提出基于满应力准则的薄板结构加强筋的设计法,假设薄板的厚度给定,壳单元的厚度为设计变量,给定约束和荷载的条件下,求加强筋在薄板上布置的几何形状,使薄板结构使用材料最省,并且满足应力约束条件.算例表明该方法简单高效,计算量小.     

磁头/磁盘超薄气膜润滑动特性计算与分析

给出了一种新的计算超薄磁头／磁盘气体润滑压力的差分算法和公式,指出了磁头偏离平衡位置的3种方式,并对超薄磁头／磁盘气体润滑问题中的动特性参数进行了计算。计算结果表明：磁头气体动压正翻刚度是影响磁头稳定的重要因素,它会使磁头越来越偏离平衡位置。     

基于CAM的数控加工后置处理方法的研究与实践

以Master CAM为例,介绍了基于CAD/CAM一体化的数控自动编程加工中的后置处理技术,以及在当前条件下如何进行数控加工后置处理.     

基于可编程定时计数器8254的滚珠丝杠螺距误差测量方法

介绍了利用可编程定时/计数器8254测量滚珠丝杠螺距误差的实现方法。8254的计数脉冲频率高,三个内部计数器具有软件锁存功能,可同时锁存三个计数器的计数值和状态,避免了由于软件读取时刻不同而造成的读数误差。实验证明,该测量系统具有测量精度高、实时性好等优点。     

A Novel Method for Quantitative Determination of Ultra-low Wear Rates of Materials, Part II: Effects of Surface Roughness and Roughness Orientation on Wear

A novel method of measurement of the very low wear-rates of materials in the ultra-mild wear regime, which involves the use of implanted gold as a marker, was used to understand the effects of surface roughness and roughness orientation on wear under reciprocating sliding conditions. AISI 1095 steel coupons with various Vickers hardness values and different surface roughness and roughness orientation relative to the sliding direction were tested under the same sliding conditions. It was found that parallel sliding causes more wear compared with transverse sliding for the harder samples (Vickers hardness (VH); 450 HV, 650 HV and 1000 HV). Furthermore, the average friction coefficient of parallel sliding is also higher than that of transverse sliding for these samples. Severe wear takes place when the samples are too soft (250 HV), resulting in the complete loss of implanted gold. Surface topographic images were taken before and after the wear tests. It was found that parallel sliding dramatically increases the surface roughness, while transverse sliding does not increase the surface roughness for harder samples (450 HV, 650 HV and 1000 HV). For the soft sample (250 HV), the surface roughness increases significantly under parallel or transverse sliding.     

基于扩散偶浓度分布模型的薄壁铜(管头)-铝(管路)-铜(接头)组合制冷管路异质金属联接技术工程研究

在中国国家自然科学基金项目《金属间化合物/陶瓷复合材料界面设计及关键制备工艺》资助下,以大幅降低制冷器铜管使用为目的,提出铜(管头) 铝(管路) 铜(管头)组合制冷管路结构,核心科学问题是Cu Al异质金属的密封焊接,提出总结性科学研究报告。 以表征异种金属材料焊接扩散规律为目的,探索基于菲克扩散定理的插入式Cu Al热连接模型。认为原子向空穴迁移或在节点间的迁移是固态金属和合金中的基本扩散运动,在溶剂晶格中溶质原子异扩散(AD)具有方向性,导致溶质原子浓度有局部变化。金属在加热或冷却过程中的相变和组织变化总是与扩散过程(DP)密切相关。固态压焊(SSPW)时,DP是确定再结晶(Recrystallization)和激活面(Surface Activation)之间结合后使焊接接头性能改善的主要过程。建立起扩散过程中溶质原子分布的一维扩散模型,由菲克第一定律建立扩散通量与扩散物质浓度和单向扩散距离的关系模型,由菲克第二定律获得扩散物单向扩散浓度模型,通过玻耳兹曼变换(Boltzmann Transform)求解任何时刻的一维浓度分布c(y,t),建立基于高斯误差函数(GEF)erf(β)的扩散偶浓度分布模型(CDM)和扩散偶浓度分布曲线(CDC)。基于CDM,建立CDC、扩散系数、原始接触面(OCS) 浓度、理论均匀化判别等工程应用层面的Cu Al焊接扩散模型。