Modelling and analysis of 3-D arrangements of particles by point processes with examples of application to biological data obtained by confocal scanning light microscopy

Within the concept of point processes, a review is presented of quantities which can be used in studies of three-dimensional (3-D) aggregates of particles. Suitable characteristics and estimators are given for both unmarked and marked point processes. To demonstrate the feasibility of such quantitative approaches, an application in histology, dealing with 3-D arrangements of cell nuclei in rat liver, is described. Using a confocal scanning light microscope, 3-D images are recorded and image analysis used to obtain the coordinates of the centroid, together with the volume and DNA content, of each cell nucleus. Examples of results are given, using both unmarked and marked point processes. In the latter case, cell type, nuclear volume and ploidy group are suitable marks.     

纳米碳管的电子衍射及其螺旋度测量

本文对电弧放电和催化剂热解碳氢气法制备的多层直形纳米碳管的倒空间及其螺旋度，采用电子衍射进行了研究。结果表明：尽管制备方法不同，两类多层管的结构相似，皆由螺旋和非螺旋的单层石墨管组成；对其倒空间的分析以及系列倾转电子衍射实验证明，衍射图中测得的表观螺旋度值随和射条件而改变，只有在垂直入射条件下该值才代表碳管的真实螺旋度；     

电子束、离子束与蓝宝石相互作用的研究

研究了电子束、离子束作用于Al2O3表面时成分的变化，表明无论电子束或离子束都能使Al2O3发生分解，产生导电的元素Al。实验在PHI610·SAM上进行，电子束轰击下（3keV，O．5μA，入射角60°）10s就有元素Al分解出来，2min以后就达到饱和，分解析出量随时间成a（1－e－bt）的关系。离子束轰击下同样发生元素Al的分解，但当Ei＞3keV时，由于剥离速率加大，溅射5min时表面Al峰反而比1min时要弱。这时表面Al含量处于分解析出与溅射剥离的动态平衡中。实验还发现了Al2O3的解析与表面成分有关（如碳的含量）。最后讨论电子束与离子束的解析机理。     

A portable cryo-storage system for low-temperature scanning electron microscopy,suitable for international transport of cryo-specimens

A cryo-specimen storage system for low-temperature scanning electron microscopy (LTSEM) specimens is described, which: liberates multi-specimen experiments from sampling restrictions imposed by the rate at which LTSEM specimens can be examined in the SEM; provides security against experiment loss resulting from breakdown of the SEM or cryo-system; enables collection of specimens in the field or in laboratories remote from the SEM laboratory; and facilitates international air transport of LTSEM specimens. The components of the system, which has a capacity of 98 stub-mounted specimens, are readily made in a laboratory workshop. The details of the design may be altered to suit particular specimen types or experimental approaches.     

电子自旋共振在橡胶研究中的应用

综述了电子自旋共振在橡胶的合成、加工和应用领域的应用现状及其发展前景。     

氮化钛薄膜的高分辨AES谱和XPS谱研究

着重讨论了TiNx薄膜俄歇电子谱的定量分析方法和X射线光电子谱中线形的变化。利用已知组元强度定量分析技术和Ti的LMV俄歇电子峰，探讨TiNx薄膜中N含量的定量方法。由该方法给出的定量结果与X射线光电子谱定量结果相一致。同时，利用X射线光电子谱测定了TiN和Ti2N2p轨道的结合能。并针对Ti2p峰形随N含量的变化，给出新的解释。     

Electrical characterization of very-narrow-gap bulk HgCdTe single crystals by variable magnetic field hall measurements

Variable-magnetic-field Hall measurements (0 to 1.5 T) are performed on very-narrow-gap bulk-grown Hg_1−xCd_xTe single crystals (0.165 ≤ x ≤ 0.2) at various temperatures (10 to 300K). The electron densities and mobilities are obtained within the one-carrier (electrons) approximation of the reduced-con-ductivity-tensor scheme. The present data together with the selected data set reported by other workers exhibit a pronounced peak when the electron mobility is plotted against the alloy composition x-value which has been predicted to be due to the effective-mass minimum at the bandgap-crossing (E_g ≈ 0). The observed position (x ≈ 0.165), height (≈4 x 10² m²Vs), and width (≈0.01 in x) of the mobility-peak can be explained by a simple simulation involving only ionized-impurity scattering. A lower bound of the effective mass is introduced as a fitting parameter to be consistent with the finiteness of the observed electron mobility and is found to be of the order of 10⁻⁴ of the mass of a free electron.     

On the applied stress dependence of the subgrain size

The present work studies the collection of experimental data from which Raj and Pharr (Mater. Sci. Eng., 81 (1986) 217) deduced a universal empirical dependence of the subgrain size on the applied stress. In accord with their result and some theoretical predictions the normalized subgrain size d_s/b was ssumed to be proportional to G/σ (G is the shear modulus, b the Burgers vector length, σ the applied stress). The evaluated factor of proportionality K₁, having the value within the interval from 0.76 to 180 in the inspected data sets, was discussed from the point of view of various factors which can influence the experimental data.     

Smithsonian Microbeam Standards

This is a short history of the Smithsonian Microbeam Standards; their sources, selection, preparation, and analyses. Fifty-eight minerals, natural glasses, and synthetic samples have been characterized in the past 25 years. During that time, over 750 requests were received for approximately 11 000 individual samples. These reference samples are referred to as the Smithsonian Microbeam Standards.     

The influence of dependence of HEMT’s model parameters on gate and drain voltages on upper boundary of LNA’s linearity

On the basis of numerical model the parameters of high electron mobility transistors (HEMT’s) as a function of gate and drain voltages are obtained. The simulation of nonlinear properties of low noise amplifier cascade with HEMT for various modes of its operation has shown that the account of its dependence simultaneously on both the voltages allows to approach the results of calculation to experimental data.