Direct determination of ultrathin section thickness using latex particles

A method is proposed to determine ultrathin section thickness by means of noncentral sections obtained from latex spheres. The resulting spherical segments provide the parameters necessary to calculate very simply the section thickness without further treatment. The method is illustrated by an example using the grid-sectioning technique and could be generalized to classical microtomy.     

Thickness variations within individual paraffin and glycol methacrylate sections

The object of this study was to investigate whether there are intra-section thickness variations in individual paraffin and glycol methacrylate (GMA) sections. Using steel or glass knives sections were cut from liver and urinary bladder. Section thickness variations were measured with an interference microscope and amounted to 1–3 μm within individual paraffin sections and 0.3 μm within GMA sections. The results were confirmed by observations on sections which had been re-embedded and re-sectioned. Some of the variations within the paraffin sections were associated with the cell nuclei. It is concluded that GMA sections are much smoother than paraffin sections and thus more suitable for quantitative histological studies.     

A technique for measuring and tuning the accelerating sections

A technique has been developed for measuring and tuning one of the accelerating sections based on a biperiodic structure with on-axis coupling cells for a 1.5-GeV double-sided racetrack microtron before and after the section is brazed. The technology and results of tuning of the microwave power input coupler for the accelerating section are described.     

Design-based estimation of surface area in thick tissue sections of arbitrary orientation using virtual cycloids

Surface area is a first‐order stereological parameter with important biological applications, particularly at the intersection of biological phases. To deal with the inherent anisotropy of biological surfaces, state‐of‐the‐art design‐based methods require tissue rotation around at least one axis prior to sectioning. This paper describes the use of virtual cycloids for surface area estimation of objects and regions in thick, transparent tissue sections cut at any arbitrary (convenient) orientation. Based on the vertical section approach of Baddeley et al., the present approach specifies the vertical axis as the direction of sectioning (i.e. the direction perpendicular to the tissue section), and applies computer‐generated cycloids (virtual cycloids) with their minor axis parallel to the vertical axis. The number of surface‐cycloid intersections counted on focal planes scanned through the z‐axis is proportional to the surface area of interest in the tissue, with no further assumptions about size, shape or orientation. Optimal efficiency at each x–y location can be achieved by three virtual cycloids orientated with their major axes (which are parallel to the observation planes) mutually at an angle of 120°. The major practical advantage of the present approach is that estimates of total surface area (S) and surface density (S_V) can be obtained in tissue sections cut at any convenient orientation through the reference space.     

A new method for the model-independent assessment of thickness in three-dimensional images

Three-dimensional (3-D) structural parameters derived from lower-dimensional measurements using indirect morphometric methods may be strongly biased if the measured objects deviate from the assumed structure model. With the introduction of 3-D microscopic measuring techniques it is possible to obtain a complete depiction of complex spatial structures. As a consequence, new 3-D methods have recently been developed for the estimation of morphometric parameters such as volume, surface area and connectivity by direct processing of the 3-D images. Structure thickness is an important morphometric parameter which is usually defined for specific structure models only. In this paper we propose a general thickness definition for arbitrary structures allowing us to calculate the mean structure thickness and the thickness distribution of 3-D objects in a direct way and independently of an assumed structure model. Additionally, an efficient implementation for the practical usage of the method is described using distance transformation. The new method is applied to trabecular bone structures measured with a 3-D micro-computed tomography system.     

A simplification of the ‘step’ method for estimating mean section thickness

An inexpensive and efficient method for estimating mean section thickness based on an estimate of the sectioning depth is presented. This value is required for the estimation of particle number using the disector.     

Estimation of the section thickness and optical disector height with a simple calibration method

The distance between the upper and lower surfaces of a section (i.e. the section thickness) can be measured with a microcator or a shaft encoder. In the present report, an alternative simple method is described for estimating the section thickness where such equipment is not available. The basic principle of the method is based on a calibration method already described in the literature. The main difference is that it enables one to make more precise measurements. Provided that the calibration and measurements are made properly, this method can be used in estimating the section thickness, optical disector heights, and in particular in the determination of the thickness sampling fraction for the optical fractionator.     

Pronounced loss of cell nuclei and anisotropic deformation of thick sections

The local deformation and variations in section thickness are studied in 100-μm thick vibratome sections of well-fixed human brain tissue. During processing, including drying on glass slides, the section thickness is reduced to less than half, but close to the edges there is less shrinkage of the section thickness. Close to both surfaces there is a pronounced reduction in the number of neuronal nucleoli. At the scale of the original section, the upper 15 μm and the lower 10 μm are depleted. The loss is most pronounced at the upper surface, which is unprotected during processing. In the central 70% of the section height, where one would ordinarily use an optical disector for sampling, there is no indication of non-uniform shrinkage. The simplest explanation for the observed loss of nucleoli is that all cells opened by the knife may lose their nuclei across an unprotected section surface. The observations do not generalize to other tissues and other preparation techniques, but illustrate the magnitude of some of the problems for uniform sampling and unbiased estimation in very thick sections. The uniform optical disector sampling of nucleoli in thick sections, as opposed to that of cell nuclei, raises a special problem, which is discussed briefly.     

激光干涉绝对重力仪数据采集与处理的时间优化方法

激光干涉绝对重力仪作为高精度绝对重力测量中的典型测量仪器,单次测量的常规流程一般是电机驱动、数据采集、重力加速度绝对值计算和结果的显示与存储。这种顺序控制过程中,存在耗时长、结果输出时间误差较大的问题。本文创新性地提出一种时间优化方法,通过建立数据采集前电机驱动与采集后数据处理两个过程时间复用机制的时间优化模型,对顺序控制方式中的各步骤进行优化与重新配置,实现缩短常规测量的测量时长,减少结果输出时间误差的目的。实测结果表明,时间优化方法将单次测量时间从原来的34.3±0.3 s,精确控制为22 s,误差5 ms,大幅提高测量效率的同时实现了单次测量时间的精准控制,也增加了与同类观测数据的融合分析的可行性。     

超声波测厚系统的研究

深孔加工是一种封闭式或半封闭式状态下的加工,其加工过程很不稳定,深孔加工刀具的走偏现象直接影响被加工孔的直线度,造成被加工工件报废,所以在深孔加工过程中的实时检测就显得尤其重要.根据深孔加工系统的特点,将超声波测厚原理用于单管内排屑喷吸钻深孔加工在线监测中,通过检测被加工工件壁厚来判断刀具是否走偏,结果表明,该测试装置较好地解决了深孔钻削加工刀具走偏的监测问题.     

The performance of some antiwear additives and interference with other additives

This paper reports work on the evolution of films formed by some antiwear additives. Between having an additive solution in a fresh lubricant and the actual deposition of protective films on the rubbing surfaces there is a gap during which the normal actions of a given additive may be affected by the presence of another additive. Film thickness is one of the most important parameters affecting wear. Interference between additives can change the chemical composition and the thickness of the films formed and, consequently, can modify the antiwear properties of the original additive.     

基于外差干涉技术测量液体费尔德常数的实验研究

为了准确测量液体的费尔德常数,设计搭建了一套外差干涉实验系统,主要包括Mach-Zehnder干涉光路、声光调制器(AOM)及锁相放大器。葡萄糖溶液测量结果显示,其费尔德常数随其浓度的增加而有变化的趋势。此外,加正与负磁场所测得的费尔德常数并不相等,其原因是加正磁场造成葡萄糖分子的形变与加负磁场所造成葡萄糖分子的形变不同,形变大其费尔德常数也就越大。蔗糖溶液测量结果发现,在加正与负磁场时所得的费尔德常数没有明显变化,其原因是蔗糖水解时产生了右旋葡萄糖和左旋果糖,使得形变效应相互抵消。     

光纤插针三维形貌检测中的干涉图像处理

对光纤插针端面干涉计量是测量其三维形貌和几何参数的一个重要而有效的方法,采用光纤端面干涉图像静态分析方法.首先,通过Canny算子边缘提取算法,得到干涉条纹的边缘,接着用改进的随机Hough变换算法检测出边缘曲线的参数,并结合等厚干涉物理模型得到光纤插针端面的各项参数,实验结果表明,这种检测方法的重复性误差在2%以内.而且能够在1s内完成一次系统计算。     

基于原子力显微镜的薄膜厚度检测系统

研制了一种基于原子力显微镜的薄膜厚度检测系统。该系统首先绘制薄膜轮廓曲线,根据曲线找到薄膜边界,然后计算镀膜区与无膜区的高度差,得到薄膜厚度。跟台阶仪、光学轮廓仪相比,该系统具有操作简单、抗干扰能力强、精度高的优点。实验表明。该系统有很高的重复性,能够精确测量各种不同性质的薄膜的厚度。     

An eddy-current gauge for measuring the wall thickness of light-alloy drill pipes

The operating principle and design of an eddy-current transducer intended for in-service measurement of the wall thickness of light-alloy drill pipes are described. The block diagram and algorithm of conversion are provided for measurement-data signals from the eddy-current thickness gauge. The main technical specs are listed for a thickness gauge prototype.     

一种弹簧端头厚度检测量规的设计

螺旋压缩弹簧端头厚度的传统检测方法是:将塞尺插入弹簧端头的间隙处,用游标卡尺的尾部抵住塞尺,尺身垂直于端头,测出端头厚度.实践证明这种方法的检具误差在⊿=1.5cotα之间.对于调压簧等旋绕比小的弹簧,卡尺与弹簧接触不稳定又会造成视觉误差,从而影响检测效果.提高弹簧端头的检测精确度,必须使用专用的检测量具准确读取数值.可将拧在(0～3mm)百分表量杆上的量头改为有尖形刃口的方形柱状表头,制作测量座.测量时,先用校对块将表头对在平面位置,表针对零.然后将弹簧端头断口正面对准表头尖头面,推动弹簧,使弹簧端面与检具平面完全贴合,百分表即可显示出准确的端头厚度数值.     

A rapid methylene blue-basic fuchsin stain for semi-thin sections of peripheral nerve and other tissues

Differential histological staining of various tissues is achieved in epon, araldite or glycol methacrylate sections 0·25–0·5 μ thick, from human, guinea-pig and rat origin. The staining procedure is as follows: 1% methylene blue in 1% borax 15–30 sec at 70°C; wash in hot water; 2% basic fuchsin in distilled water 1–2 min at room temperature; wash and mount in DPX. Results: with all tissues: nuclei pale violet, cytoplasm blue. Special histological components: collagen red, myelin deep blue, elastin deep violet, axoplasm pale blue. Although of general utility the method is especially useful for peripheral nerve and blood vessels.     

剪切干涉仪的定量处理数学原理及采样处理技巧

介绍了剪切干涉仪适时定量处理的方法。通过互相垂直两个方向的剪切图形 ,解算出镜面的实际形状。提出两种处理方法 :即变换系数法和扩展了的联立方程求解法。然后介绍了在采样和处理过程中的技巧 ,最后对剪切干涉棱镜的发展和如何将移相干涉技术应用到剪切干涉中的可能性 ,做了初步的探讨。     

Measurement of the optical thickness of transparent tissue layers

The method of Due de Chaulnes was employed to determine the mechanical and optical thickness, as well as the refractive index, of transparent tissue layers in living specimens. To this end the reproducible accuracy of the method and its dependence on the adjustment in focusing and on the numerical aperture of the objective was evaluated on test specimens using the procedures of transmitted light, phase-contrast (PC), and differential interference contrast (DIC) microscopy. The best working conditions were then applied to the actual measurements.