Applications of medium-voltage STEM for the 3-D study of organelles within very thick sections

Scanning transmission electron microscopy at 300 kV enables the visualization of nucleolar silver-stained structures within thick sections (3–8 μm) of Epon-embedded cells at high tilt angles (–50°; + 50°). Thick sections coated with gold particles were used to determine the best conditions for obtaining images with high contrast and good resolution. For a 6-μm-thick section the values of thinning and shrinkage under the beam are 35 to 10%, respectively. At the electron density used in these experiments (100e^—/Å₂/s) it is estimated that these modifications of the section stabilized in less than 10 min. The broadening of the beam through the section was measured and calculations indicated that the subsequent resolution reached 100 nm for objects localized near the lower side of 4-μm-thick sections with a spot-size of 5·6 nm. Comparing the same biological samples, viewed alternately in CTEM and STEM, demonstrated that images obtained in STEM have a better resolution and contrast for sections thicker than 3 μm. Therefore, the visualization of densely stained structures, observed through very thick sections in the STEM mode, will be very useful in the near future for microtomographic reconstruction of cellular organelles.     

Applications of confocal microscopy in industrial solid materials: some examples and a first evaluation

We report here the first results of the application of confocal scanning laser microscopy (CSLM) for the study of the microstructure of solid industrial materials. Glass-fibre-reinforced composites, heterogeneous and conductive polymers, homogeneous as well as heterogeneous catalyst (precursor) specimens and soils were examined. We conclude that both the fluorescence and reflection modes of CSLM can yield valuable information. In particular, the optical sectioning capability of CSLM appears to be of great value as it enables one to access the 3-D organization of the specimen without the need for a difficult and time-consuming specimen preparation procedure. However, local obscuration may be an important factor in confocal image formation, limiting the penetration capabilities of the technique for industrial materials.     

SL450水龙头中心管螺纹齿根表面裂纹应力强度因子三维有限元分析

采用三维有限元位移法求解水龙头中心管齿根危险截面上含不同形态和不同深度椭圆表面裂纹，在拉伸和内压载荷作用下的应力强度因子。较精确地给出了应力强度因子沿裂纹前缘的变化规律。在大量有限元数据结果的基础上，拟合出应力强度因子的计算表达式，为预测带裂纹的水龙头中心管的承载能力、剩余寿命、确定探伤周期、制定判废标准提供了必要的断裂分析参数。     

膨胀烟丝冷端管道三维配管设计

三维配管技术在石化行业有着广泛的应用,论文运用PDSOFT三维配管软件对烟草工业中膨胀烟丝生产线冷端部分的管道进行三维设计,提高了设计精度,减少了管道碰撞。并且采用CAESARII对压力管道进行应力分析,确保配管设计安全性和可执行性。总结了膨胀烟丝冷端管道设计的技巧,为三维管道设计在烟草工业中的进一步应用提供了有力的支持。     

Three-dimensional imaging of human stem cells using soft X-ray tomography

Three-dimensional imaging of human stem cells using transmission soft X-ray tomography (SXT) is presented for the first time. Major organelle types—nuclei, nucleoli, mitochondria, lysosomes and vesicles—were discriminated at approximately 50 nm spatial resolution without the use of contrast agents, on the basis of measured linear X-ray absorption coefficients and comparison of the size and shape of structures to transmission electron microscopy (TEM) images. In addition, SXT was used to visualize the distribution of a cell surface protein using gold-labelled antibody staining. We present the strengths of SXT, which include excellent spatial resolution (intermediate between that of TEM and light microscopy), the lack of the requirement for fixative or contrast agent that might perturb cellular morphology or produce imaging artefacts, and the ability to produce three-dimensional images of cells without microtome sectioning. Possible applications to studying the differentiation of human stem cells are discussed.     

基于改进CAF-WAS的绑定前硅通孔测试

硅通孔TSV发生开路故障和泄漏故障会降低三维集成电路的可靠性和良率,因此对绑定前的TSV测试尤为重要。现有CAF-WAS测试方法对泄漏故障的测试优于其他方法(环形振荡器等),缺点是该方法不能测试开路故障。伪泄漏路径思想的提出,解决了现有CAF-WAS方法不能对开路故障进行测试的问题。另外,重新设计了等待时间产生电路,降低了测试时间开销。HSPICE仿真结果显示,该方法能准确预测开路和泄漏故障的范围,测试时间开销仅为现有同类方法的25%。     

纤维铺放虚拟数控系统设计

根据复合材料纤维自动铺放的原理,基于VC++编程搭建纤维铺放虚拟数控系统,主要包括三维模型的建立、虚拟数控单元的构建和运动仿真的实现。在虚拟数控单元中加入速度处理模块,符合实际,能得到比较好的铺放效果。最后通过一个实例对软件仿真效果进行验证。     

Implication of Size-Controlled Graphite Nanosheets as Building Blocks for Thermal Conductive Three-Dimensional Framework Architecture of Nanocarbons

Preparation of three-dimensional (3D) networks has received significant attention as an effective approach for applications involving transport phenomena, such as thermal management materials, and several nanomaterials have been examined as potential building blocks of 3D networks for the improvement of heat conduction in polymer nanocomposites. For that purpose, nanocarbons such as graphene and graphite nanoplatelets have been spotlighted as suitable filler materials because of their excellent thermal conductivities (ca. 10²–10³ W·(m·K)^?1 along their lateral axes) and morphological merits. However, the implications of morphological features such as the lateral length and thickness of graphene or graphene-like materials have not yet been identified. In this study, a controlled dissociation of bulk graphite to graphite nanosheets (GNSs) using a low-cost, ecofriendly bead mill process was extensively examined and, when configured in a 3D framework architecture formation, the size-controlled GNSs demonstrated that the thermal conductivities of a 3D interconnected framework of GNSs and the corresponding polymer nanocomposite were intimately correlated with the size of the GNSs, thus demonstrating the successful preparation of an efficient thermal management material without highly sophisticated efforts. The capability of controlling the lateral size and thickness of the GNSs as well as the use of a 3D interconnected framework architecture should greatly assist the commercialization of high-quality graphene-based thermal management materials in a scalable production process.     

异形玻璃幕墙安装测量精度分析

随着玻璃幕墙在建筑中的广泛应用，各种异形玻璃幕墙的出现对安装测量方法提出了更高的要求。本文结合唐山人民大厦的实例，介绍了采用免棱镜全站仪进行玻璃幕墙三维测量的方法，并提出了相应的精度控制措施。     

数字化三维虚拟演播室系统方案设计

数字化三维虚拟演播室系统将摄像机现场拍摄人物活动图像和三维虚拟物体图像制作进行数字化的实时完美结合.首先介绍了数字化三维虚拟演播室的特点,然后叙述了三维虚拟演播室系统项目需求,最后从设计原则、系统结构设计、系统设备、系统显著特点等方面阐述新余台数字化三维虚拟演播室系统的设计方案.