The pore structure of chrominophosphate catalysts

A series of chrominophosphates (CrPs) with various P/Cr ratios were prepared by the precipitation method. The pore structures of these catalysts were characterized by nitrogen adsorption and mercury-penetration porosimetry. The results indicated that the micro-pores with diameters less than 20 nm were due to the dehydration process and had a slit-shaped geometry. There were two types of large pores (meso- and macro-) with diameters greater than 20 nm. These pores had a cylindrical pore-shape. The meso-pores can be attributed to the packing of particles and the macro-pores are essentially due to the packing of the aggregates of the particles.     

Poly(methyl methacrylate) and polyacrylonitrile dispersions stabilized by gelatin

Methyl methacrylate was polymerized in an aqueous medium in the presence of gelatin using potassium persulfate as initiator. The dispersion mode of polymerization, when the monomer is completely miscible with water, was investigated and compared with an emulsion process, which proceeds at higher monomer concentration. Spherical and relatively uniform polymer particles were formed. Macroscopic precipitation of polymer is prevented by combination of the steric stabilization by grafted gelatin and of repulsive electrostatic interactions from the initiator residues attached to the particle surface. Static and dynamic light scattering have been used to determine the molar mass (molar mass of the whole dispersion particle, M_wD ～ 10⁸-10⁹ g mol^?1) and hydrodynamic radius (R_hD ～ 50-120 nm) of the particles. The number of particles per unit volume does not depend on overall monomer concentration, and it is higher, and therefore the particle size is smaller, than that observed for the soapless emulsion polymerization. The addition of gelatin may be thus used to modify the particle size. Acrylonitrile dispersions were prepared under similar conditions. Unlike methyl methacrylate, this monomer does not swell the polymer particles. While poly(methyl methacrylate) particles are spherical and relatively uniform, the polyacrylonitrile dispersions consist of polydisperse aggregates of tiny polymer particles.     

光电装备的光学窗口激光变换特性研究

本文提出一种方法，利用激光扫描战场上光电装备光学窗口并研究其对激光的变换特性，从而建立这些光电装备的变换特性数据库，它在未来的光电对抗（尤其是战术激光武器）、激光主动侦察和识别以及激光雷达等领域将发挥重要的作用。     

采用扫描电镜的ECP技术分析人工合成金刚石晶体中的晶体缺陷

本文应用扫描电镜的ＥＣＰ技术对人造金刚石晶体表面的位错密度，进行了实验分析，并同位错蚀坑分析技术的测量结果进行了比较，结果表明，如采用临界束流强度作为描述ＥＣＰ本征衬度的参数，则它同位错密度间存在明显定量的数学关系，因此上述临界束流强度可用来评价晶体中位错密度的相对变化。     

DATABASE FOR ORGANIC SULFUR COMPOUNDS USING GC-SCD METHOD. DETERMINATION OF SULFUR CONTAINING COMPOUNDS IN STRAIGHT RUN GAS OBLS (SRGO)

Sulfur standards were studied on a high resolution gas chromatograph (GC) “HP 5890 series II plus ”. Retention times were determined for each individual compound, A sample of straight run gas-oil (SRGO) was analyzed by coulomax method for total sulfur and by GC equipped with sulfur chemiluminescence detector (SCD) for individual sulfur identification, A database for about 165 sulfur compounds was established. Using relationship between total sulfur contents determined by coulomax method and sura of individual sulfur compounds determined by GC-SCD the quantity of different sulfur compounds in SRGO was determined     

用拉盖尔─高斯函数表示梯度型单模光纤的特性参数

本文用拉盖尔－高斯函数来表示梯度单模光纤的特性参数。恰当应用拉盖尔多项式的性质和汉格尔交换理论，光纤参数如远场分布，模斑尺寸等可以有解析式计算，结果十分简单且物理意义明确。文中给出了数值计算结果并与准确值进行了比较，最后讨论了本文方法的优点．     

基坑支护优化设计的数学模型研究

基坑支护设计属于系统工程设计,包括方案设计和细部结构设计两个层次,相应地,基坑支护设计变量具有层次性、结构性和不确定性．对此,提出了基于搜索的基坑支护协同优化设计分析模型,给出了与方案、细部和子细部优化相对应的数学模型,并讨论了总系统优化与各子系统优化即全局寻优与局部寻优的关系,得出“必须求解能全面反映各子系统间各种耦合关系的总系统才能得到基坑支护系统的全局最优解”的结论。     

Nitrogen adsorption method for determining the mesopore slit-like size distribution of expansive soils

One of the most important structural parameters involved in the characterization of the void space of soils is the pore size distribution. In this work, a nitrogen adsorption method is presented as an alternative to determine the mesopore contribution of slit-shaped pores to the abovementioned parameter in montmorillonite-containing soils. The mesopore size structural parameter obtained via this sorption method is related to montmorillonite d₀₀₁ interlayer distances proceeding from either X-ray or electron diffraction analysis, if only by assuming during sorption analysis that mesopores resident inside clay grains adopt slit-shaped geometries. Mineralogical analysis and determination of some important geotechnical properties of these montmorillonite-containing soils complement the preceding sorption and structural studies.     

Prevention of La^3＋ on DNA Damage Caused by Hg^2＋ from Fish Intestines

Recent studies have shown that heavy metals havebecome the most important contaminants in the environ-ment.Some heavy metals ,such as Pb, Cd, Hg, As ,Co,and Cr have genetic toxicity. They disturb DNAmetabolismand lead to aberrance of chromosome andDNA[1].…