Immunocytochemical localization of amelogenin in rat incisor ameloblasts using ultrathin frozen sections

The localization of amelogenin, an enamel matrix protein, was examined by ultrastructural immunocytochemistry using unembedded ultrathin frozen sections of undecalcified rat incisor ameloblasts. Antibody against bovine amelogenin labeled Golgi complexes, secretory granules, and lysosomal structures in the preameloblasts and inner enamel-secretory ameloblasts as well as the enamel. The antibody also labeled dentin matrix facing preameloblasts. These results support the findings in previous reports using conventional epon embedded specimens. However, rough-surfaced endoplasmic reticulum failed to be labeled by this antibody.     

一种快速简便的超薄切片选择性染色法

利用铀 铅 铜选择性染色技术 ,能使细胞中线粒体和高尔基体染色很深 ,内质网也有一定程度的染色 ,而细胞核和其它细胞质成分染色很淡 ,便于分析统计线粒体的面积 ,研究高尔基体和内质网的关系等 ,对生物医学的研究工作提供了一种新的方法[1,2 ] 。但此法染色时间过长且容易出现污染样品的现象。现我们采用微波辐射技术 ,加快制样染色过程 ,取得满意的效果[3 ] ,现介绍如下。材料和方法1 主要仪器 :本实验所用微波炉的型号为Ｗｂｌ 5 30 0 1型 (国营陕西通达电器厂生产 )工作频率为2 4 5 0ＭＨｚ ,最大输出功率为 5 30Ｗ。微波辐射时在微…     

培养细胞凋亡的半薄与超薄切片的比较

细胞凋亡与细胞坏死在形态学方面有着显著的差别,通常电镜观察结果是证明细胞凋亡的最可靠的证据。我们认为细胞凋亡的半薄切片甲苯胺蓝染色更加简便、快速,且较准确。本实验采用地塞米松诱导Ｊｕｒｋａｔ细胞凋亡的模型,采用半薄切片的光镜观察及超薄切片透射电镜观察。结果表明,半薄切片可以初步判断凋亡细胞,透射电镜观察是确定细胞凋亡的直接证据,且方法稳定,结果可靠。     

电镜超薄切片真空染色法

介绍一种简便易行的超薄切片真空染色法。使用简单易得的工具及自制装置-真空保鲜盒、染色硅胶板和染色硅胶板架,能够得到较好的染色效果。结果显示,与目前现有的传统方法相比较,超薄切片真空染色法省时、省试剂,染色效果好,一次可进行大批量切片染色(一次可达200张超薄切片)。     

超薄切片表面高低起伏反差机制的初步探索

自AFM发明以来，用它来进行各种超薄切片表面形态学研究的报道屡见不鲜，包括形态学的比较研究、关键结构的识别、精细结构的定量化研究等等。但是长期以来一个关键性的问题就是：为什么用超薄切片法得到的各种厚度不同的超薄切片表面会存在纳米级的高低起伏?且这种起伏能够反映组     

Measurement of CdxHgi-xTe composition depth profiles using auger electron spectrometry on bevelled sections

The width of the band gap in the ternary system Cd_xHg_I-xTe (CMT) is a function of the value of x and the assessment of device structures requires reliable techniques for the measurement of x both laterally and with depth. This work describes the development of an Auger electron spectrometry (AES) method for the measurement of CMT composition depth profiles, based on measurement of the Cd/Te ratio along shallow-angle bevelled sections through epitaxial layers. Results are accurate to within 3% relative and the depth resolution (Δz = 2σ) is about 0.04 μm even through layer structures with a total thickness of about 20 μm. Techniques for making the bevel sections are described together with the AES measurement and calibration techniques. A composition depth profile is given for a heterostructure grown by metal organic vapour phase epitaxy (MOVPE), showing the interface width (Δz = 2σ) at the composition change to be 0.3 μm. The CdTe/CMT interface widths in material grown by liquid phase epitaxy (LPE), MOVPE and molecular beam epitaxy (MBE) are shown to be highly dependent on growth temperature, with widths of 1.5, 0.2 and ? 0.04 μm respectively.     

人舌鳞癌组织超薄切片的AFM成像和切割

利用一种基于电镜超薄切片法改进的制样方法，将人舌鳞状细胞癌病理组织以环氧树脂包埋并切片后，将薄片平整地贴附在云母上，用原子力显微镜(AFM)对切片表面进行研究，可以得到高分辨率的细胞超微结构图像，局部的亚细胞水平的形态结构可以与电镜下得到的图像相比拟。在此基础上，利用AFM针尖对肿瘤细胞核内特定区域进行切割和操纵，形成生物分子的堆积，从而为拾取(pjck—up)和进一步用分子生物学手段在亚细胞基因水平研究人舌鳞癌的病理学奠定了基础。     

金属平板的太赫兹雷达散射截面测量

为了测量金属平板的雷达散射截面,分别采用了太赫兹时域光谱系统和0.1 THz连续波测量系统两种方法进行测量,并从理论上分析了雷达散射截面测量模型。结果表明,对于太赫兹时域光谱系统,随着测量频率和角度的增加,其误差在增大;对于0.1 THz连续波测量系统,随着角度的增加,误差增大,随着被测目标尺寸增大,误差先减小后增大,实验最小误差均可达到-0.244dB。利用太赫时域光谱系统及0.1 THz连续波测量系统测量雷达散射截面均是可行的。太赫兹时域光谱系统具有频率取值范围大、角分辨率高的特点;而0.1 THz连续系统系统结构简单、成像速度快、使用方便。     

Measurement of s.a.w. device stripe/period ratio using optical diffraction

The stripe/period ratio of periodic s.a.w. device masks has been determined by measuring the intensity of the diffraction maxima obtained when a laser beam is transmitted through the mask. Correlation of measured data with theoretical results is excellent. The technique can also be used to measure the stripe/period ratio on actual s.a.w. devices.     

一种多周期测量频率的方法及应用

利用多周期测量方法,通过对信号进行分频准确测量出气压传感器输出信号的周期和频率。利用P89LPC935内部的A/D转换器测量环境温度进行温度补偿,选取准确度优于5 ppm的晶振,测量周期的误差最小可控制在0.001 1μs。该测量方法成功地应用于与河南省气象局合作开发的自动气象站中。用多周期测量的方法快速准确测量信号的频率(周期)基于2个条件:信号是连续的;单片机的晶振必须使用外接的高精度、高稳定晶体振荡器。     

干涉直条纹周期测量及其在位相检测中的应用

干涉条纹周期是干涉精密测量中的一个较为重要的参数.为了可以简单快速而不失准确性地测量条纹周期,采用了图像处理实现干涉条纹周期测量的较为简单实用的算法.通过MATLAB平台设计相应的图像数据处理软件,分析影响条纹周期测量精度的因素,给出处理过程对条纹倾斜度的要求,并应用于相板的位相的定量检测,获得了相板的位相大小.结果表明,测量相位精度达λ/20～λ/50或π/10～π/25.这一结果对位相物体的厚度和折射率的测量有很大的帮助.     

Observation of ballistic transport in hot-electron vertical FET spectrometer using ultrathin planar-doped barrier launcher

Experimental evidence of ballistic transport by hot electron injection into a GaAs vertical FET channel using an ultra-thin planar-doped barrier has been obtained for the first time. The spectroscopy exhibited a narrow energy spread of less than 50 meV with an estimated 10% ballistic electrons.<>     

Implementation of 2-D denominator-separable digital filters using first-order all-pass sections

It is established that denominator-separable transfer functions which characterize an important subclass of 2-D filters can be expressed as a linear combination of first-order (1-D or 2-D separable) all-pass transfer functions with real or complex coefficients. This type of expansion is referred to as all-pass expansion of the corresponding transfer function. Based on this all-pass expansion, we derive some efficient structures for the realization of 2-D denominator-separable filters using all-pass sections.On leave from S.V. University College of Engineering. Tirupati-517502, India.     

Accurate synthesis of inline prototype filters using cascadedtriplet and quadruplet sections

A general method for designing low-pass prototype networks with cascade inline topology is presented. The generalized Chebyshev characteristic is imposed, allowing an equiripple response in the passband and transmission zeros arbitrarily displaced in the complex plane (symmetry with respect to the imaginary axis is, however, required). A computationally efficient method is employed for evaluating reflection and transmission polynomials, given the transmission zeros; then, the synthesis of a starting coupling matrix is performed using one of the methods available in the literature. The desired inline topology is then assembled by cascading elementary building blocks (triplets and/or quadruplets), following specific rules which assure the feasibility of the structure; finally, the synthesis is performed by applying a multiple similarity transform to the starting coupling matrix (the set of rotation angles is determined by means of an efficient and fast optimization procedure). Examples are reported which validate the proposed synthesis procedure     

Scattering cross sections for composite rough surfaces using the unified full wave approach

The full wave approach is used to derive a unified formulation for the like and cross polarized scattering cross sections of composite rough surfaces for all angles of incidence. Earlier solutions for electromagnetic scattering by composite random rough surfaces are based on two-scale models of the rough surface. Thus, on applying a hybrid approach physical optics theory is used to account for specular scattering associated with a filtered surface (consisting of the large sonic spectral components of the surface) while perturbation theory is used to account for Bragg scattering associated with the surface consisting of the small scale spectral components. Since the full wave approach accounts for both specular point scattering and Bragg scattering in a self-consistent manner, the two-scale model of the rough surface is not adopted in this work. These unified full wave solutions are compared with the earlier solutions and the simplifying assumptions that are common to all the earlier solutions are examined. It is shown that while the full wave solutions for the like polarized scattering cross sections based on the two-scale model are in reasonably good agreement with the unified full wave solutions, the two solutions for the cross polarized cross sections differ very significantly.     

Measurement of the minority-carrier lifetime using an MOS capacitor

A simple technique is described for the measurement of the minority-carrier recombination lifetime using an MOS capacitor operating as a charge injection device. Device lag resulting from the incompleteness of the charge injection process is measured as a function of the injection pulse width. An approximate diffusion model consisting of only one adjustable parameter, the recombination lifetime, is able to explain the observed lag data. The values of the recombination lifetime thus obtained are in good agreement with those measured by photoconductive decay for a variety of Si samples. This technique permits a more definitive measurement of the minority-carder lifetime in fabricated devices than presently used procedures, without requiring high-quality devices. This technique should be particularly useful for evaluating III-V and II-VI compound semiconductors because MOS capacitors with a low density of interface states often are not available.     

Measurement of physical constants using noise

Measuring physical constants by examining suitable types of noise has a long history. In this experiment, in contrast to previous works, the computer does much of the data gathering and processing. Once an undergraduate student understands the elements of the theory of thermal and shot noise, a little bit about Windows commands that interface with the SoundBlaster, and something of the filter design using MATLAB, the student will be able to design the apparatus and implement the measurements described in this article. Using well-known formulas for thermal and shot noise, we designed experiments for measuring two physical constants: the Boltzmann constant and the charge on the electron. We were able to perform the experiments in a particularly simple fashion by making use of widely available computer-based measurement and processing tools. In particular, the measurement of the Boltzmann constant only required one operational amplifier and three resistors. Our measurements achieved reasonable accuracies, considering the nature of the instruments with which we performed the measurements. The experiments are well suited to use in a laboratory setting, and they allow one to see some of the connections between random noise, physics and signal processing.