粉末材料中微夹杂缺陷的超声波检验

介绍了用超声波方法检测微夹杂缺陷的一些试验结果，比较了不同频率、不同试验方法检测能力的差异，并通过解剖试验对检出缺陷的性质、尺寸作了比较。     

The Effect of the Charge Fluctuation of Dust Parti-cles on Ion-acoustic Wave Excited Through Ionization Instability

The effect of the charge fluctuation of dust particles on ion acoustic wave (IAW) excited through ionization instability was investigated. The hydrodynamic equations and linear time-dependent perturbation theory served as the starting point of theory, by which the dispersion relation and growth rate of the IAW were given. By comparing the results with the case of constant dust charges, it was found that the charge fluctuation of dust particles reduces the instability of the wave mode.     

悬沙中D〉0．06mm粗粒的粒析级配组成及其改正方法

本文首先简述Ｄ＞０．０６ｍｍ泥沙的粒析沉降特性及其粒径偏粗的原因。继之对悬沙中粒径大于０．０６ｍｍ的粒析级配组成机理，及级配组成不同对标准粒径Ｄｂ与粒析粒径ＤＬ关系的影响进行了详细研究。在以上研究工作的基础上，开展了Ｄｂ与ＤＬ的比较试验，得出了粗、中、细型悬沙的Ｄｂ～ＤＬ关系和对ＤＬ的改正方法。     

高透明耐冲击聚氯乙烯接枝聚合研究

研究高透明耐冲击聚氯乙烯接枝聚合工艺，讨论了加料顺序、复合分散体系以及采用聚集粒子乳液、并用碱性物质调节其ｐＨ值等对接枝聚合物性能的影响，确定了接枝聚合最佳工艺条件。     

泥浆制备中工艺改造的研究

根据室条件下粉磨试验结果，发现球磨过程中筛上料变化存在的突变范围，提出两次加料一次加水可改变泥浆颗粒分布，并找出适宜的加料种类与时间。另外给予测粒度分布提供了宝贵的试验基础数据。     

Direct preparation of particles from liquid suspension for ESEM or SEM analysis

A simplified method for the preparation of particles from liquid suspensions has been developed. Particles are deposited directly on carbon planchets for rapid analysis by environmental scanning electron microscopy or by conventional scanning electron microscopy after an additional drying step. This is accomplished by filtering the liquid through thin carbon planchets. Three different grades of graphite were investigated for their suitability as the source material for these planchets. The high quality isomolded graphite is recommended for the filtration and direct observation of particles by electron microscopy. This technique is demonstrated for particles in hydraulic fluid and aquatic suspended particulate material from a natural water source.     

A polydispersed particle system representation of the porosity for non-saturated cementitious materials

In this paper, the porosity of cementitious materials is described in terms of pore size distribution by means of a 3-dimensional overlapping sphere system with polydispersivity in size. On the basis of results established by Lu and Torquato [B. Lu, S. Torquato, Nearest-surface distribution functions for polydispersed particle systems, Phys. Rev. A 45(8) (1992) 5530-5544] and Torquato [S. Torquato, Random Heterogeneous Media: Microstructure and Macroscopic Properties. Springer-Verlag: New York, 2001] providing relations for nearest-neighbor distribution functions, the volume fraction of pores having a radius larger than a prescribed value is explicitly expressed. By adopting an appropriate size distribution function for the sphere system, it is shown that the pore size distribution of cementitious materials as detected for instance by mercury intrusion porosimetry (MIP), which generally points out several pore classes, can be well approached. On the basis of this porosity representation, the evaluation of the capillary pressure in function of the saturation degree is provided. The model is then applied to the simulation of the saturation degree versus relative humidity adsorption curves. The impact of the pore size distribution, the temperature and the thickness of the adsorbed water layer on these parameters are assessed and analyzed for three model materials having different pore characteristics.     

Feasibility study on the use of polyallyldiglycol-carbonate cell dishes in TUNEL assay for alpha particle radiobiological experiments

In the present work, we have studied the feasibility of a method based on polyallyldiglycol-carbonate (PADC) films to investigate the effects of alpha particles on HeLa cervix cancer cells. Thin PADC films with thickness of about 20 μm were prepared from commercially available CR-39 films by chemical etching to fabricate custom-made petri dishes for cell culture, which could accurately record alpha particle hit positions. A special method involving “base tracks” for aligning the images of cell nuclei and alpha particle hits has been proposed, so that alpha particle transversals of cell nuclei can be visually counted. Radiobiological experiments were carried out to induce DNA damages, with the TdT-mediated dUTP Nick-End Labeling (TUNEL) fluorescence method employed to detect DNA strand breaks. The staining results were investigated by flow cytometer. The preliminary results showed that more strand breaks occurred in cells hit by alpha particles with lower energies. Moreover, large TUNEL positive signals were obtained even with small percentages of cells irradiated and TUNEL signals were also obtained from non-targeted cells. These provided evidence for the bystander effect.     

川中丘陵区一种新型小流域径流输沙模型的建立与应用

径流输沙模型对定量评价水沙的输出响应具有重要的意义。本研究在已有研究成果的基础上，通过对四川盐亭县林山西沟小流域的径流、泥沙进行现场观测与分析，提出含沙量单位线的定义及其确定方法，建立了适应该小流域的径流输沙模型。并应用实测资料进行比较，表明模型的模拟结果可靠，模拟过程确定性系数达0．8以上，为川中丘陵区小流域径流输沙过程的预测预报提供了一个新方法。     

Solid State Concepts to Understand Catalysis Using Nanoscale Metallic Particles

New advances in theoretical background and recent experimental results concerning nanometer scale metallic clusters are presented. We will begin by a presentation of the advantages and the limitations of synchrotron radiation techniques to characterise nanometer scale entities. Then, through a review of recent papers, we try to make a link between metallic surfaces and nanometer scale monometallic clusters in the case of the interaction with a small molecule, namely NO.