人群头发元素分布及某些特征研究

本文介绍用堆中子活化分析法测定人群头发中I、Br、Mg、Mn、Cu、Na、V、Cl、Al、Ca、S等11种元素。研究人发中元素分布特征、相关性特征、性别年令分布特征。方法学中还从法庭科学应用角度介绍同一性识别中差异率和重合几率的双判据方法。     

AXIAL PHASES DISTRIBUTION AND HOMOGENIZATION IN THREE-PHASE FLUIDIZED BEDS

We have investigated the axial distribution of the liquid phase in a three-phase fluidized bed in which the particles were glass beads of two different diameters, 710-850 μm and 2 mm. Two methods were used to reduce the axial heterogeneity and homogenize the bed: the use of packing elements and the addition of a small quantity of a high molecular weight polymer. The use of packing elements was shown to be very efficient in controlling phases distribution in the bed. The packing consisted of 1 mm thick steel horizontal plates punched and stretched to obtain parallelogram-shaped openings. The addition of a high molecular weight polyisobutylene (BASF Oppanol B246, M_u, =6.15 Lo⁶) on the phase distribution was also studied. Low polymer concentrations up to 397 ppm (based on the liquid phase) were investigated. The addition of the polymer reduced bubble coalescence and allowed for a better distribution of the phases.     

Moisture Distribution and Dewatering Efficiency for Wet Materials

This review paper summarizes current research efforts toward a comprehensive view of wet material dewatering, considering the binding energy as the strength to hold water, and rupture energy given to remove moisture from materials.     

充油S-SBR加工行为的研究

在中试装置上合成相对分子质量分布较宽的充油S-SBR，考察不同环烷油和芳烃油填充量的充油S-SBR的流变性能和混炼行为。结果表明，增大油的填充量能提高充油S-SBR的流动性能，充芳烃油S-SBR相对于充环烷油的S-SBR对温度更敏感，宽相对分子质量分布的充环烷油S-SBR的混炼性能优于S-SBR1204及E-SBRl778，竟相对分子质量分布的充芳烃油S-SBR的混炼性能优于S-SBR1204，Solprene380和E-SBR1712。     

生物质中元素分布特征的聚类分析研究

测定了稻草秆、小麦秆、玉米秆、棉花秆、大豆秆、玉米芯、花生壳和柳树、松树、桦树、杨树、杉树 1 2个农业生物质和林业生物质种类 2 7个样品中主要元素 K,Ca,Na,Mg,Al,Fe,P和痕量元素 As,Cr,Co,Cu,Cd,Mn,Mo,Ni,Pb,Ti,Zn,V,Si,Ba,Be,Se,Sb,Ge,Hg的含量 ,并用SPSS聚类分析法分别进行了 R型和 Q型聚类研究 ,对这些元素在生物质中的分布特征进行了研究 .结果显示 :杨木、杉木和桦木与松木和柳木归成一大类 ,经济类作物黄豆秆和棉花秆分别归类后又归入一大类 ;农业生物质稻草秆和小麦秆、玉米秆被归入一类 ;虽然 2 7种生物质样品分别取自我国东北、华东、华北和西南地区 ,在地理位置上相距极远 ,但样品聚类谱系图表明 ,元素的分布特征与生物质的种类的关系显著 ,与产地的关系不明显 ,即元素的分布特征受种类的影响大 ,而受生长环境、气候、土壤条件的影响小 .     

Characterization of microporous-mesoporous MCM-41 silicates prepared in the presence of octyltrimethylammonium bromide

MCM-41 silicates prepared in the presence of octyltrimethylammonium bromide either by a conventional method or by post-synthesis hydrothermal treatment were characterized by nitrogen adsorption in a wide range of relative pressure from 10^-6 to 1. Hydrothermally restructured samples were found to have lower BET surface areas, lower external surface areas and thicker silica walls than the non-treated sample. More importantly, in addition to their characteristic mesopores (ca. 3 nm), they were shown to have considerable amounts of micropores. The relative amount of micropores and mesopores was shown to be dependent on the treatment conditions. Thus, it is demonstrated that the postsynthesis hydrothermal restructuring is a convenient synthesis route to MCM-41 silicates with bimodal pore size distribution involving controllable amounts of microporosity. This revised version was published online in July 2006 with corrections to the Cover Date.     

种子法制备聚合物乳液技术的进展

从建筑乳液的生产现状、自生种子法与外加种子法的区别、种子乳液的特点及外加种子法生产的乳液特性等方面介绍了种子法制备乳液技术的进展。     

COMPUTER SIMULATION OF HYDRODEMETALLATION IN FIXED-BED REACTORS

An isothermal model for hydrodemetallation (HDM) of crude oils in catalytic fixed-bed reactors is proposed. This model involves a consecutive reaction mechanism, which is capable of accounting for particle deposit profiles with interior maxima. Consistent with the fact that HDM catalysts are conglomerates formed by precipitation, the porous catalyst itself is modeled as randomly overlapping spheres of equal size. The metal is deposited as growing metal sulfide crystallites on the inner surface of the catalyst. These crystallites originate from a certain number of randomly scattered nuclei and increase in size as the deposition proceeds. The random sphere model for the catalyst and the deposit provides the changes in the catalyst pore structure—local porosity and surface area.

The mass transport within the domain of the particle is due to restricted liquid diffusion, since the diameter of the metal bearing compound (porphyrin) and the intermediate are comparable to the pore size. The diffusion restrictions taken into account are the enhanced drag imposed on a molecule by adjacent pore walls and steric partitioning.

Since the deposition process is much slower than diffusion and reaction, the pseudo-steady-state assumption can be justified. The equations of conservation for mass are solved by orthogonal collocation on finite elements. Based on this solution technique a computer simulation program of HDM is designed that allows two modes of operation: constant temperature and constant conversion. The simulation program “SIMULA” is highly flexible with regard to reaction kinetics, catalyst structure, reactor design, and operating conditions. In comparison to a base case with uniform activity, the effect of intraparticle (radial) and bed (axial) activity profiles on the conversion rate is discussed. For the case investigated, a radial distribution of activity higher at the center of the particle than at the edge can increase catalyst life by 25%, but axial distribution was less successful.     

Configurational statistics of copolymers prepared by complex-radical polymerization

Radical copolymerization is considered theoretically taking into account the effect of complexing on the configurational statistics of macromolecules formed. Akinetic model has been developed that considers, apart from the ordinary addition of single monomer units to a propagating chain, the possible addition of monomer unit pairs along with a complexing agent in the form of a ternary complex. Within the framework of this model, the problem of calculating the probabilities of formation of any sequences of monomer units (taking into account their microtacticity) in a macromolecule has been rigorously solved as well as the problem of finding the composition distribution of the copolymer formed. It has been shown that this distribution is described by a conventional Gauss law and the appropriate parameters are given. Possible generalizations of the suggested approach are indicated.     

HS2000分布式控制系统在小氮肥厂的应用

介绍了国产ＨＳ２０００分布式控制系统首次在山东禹城化工总厂尿素装置上成功应用的情况。