多孔硅表面Ag层对吸附其上的若丹明B染料分子表面增强Raman散射的影响

采用溶液电镀方法在多孔硅表面制备纳米尺寸的银颗粒,测量了不同镀银多孔硅表面吸附的ＲｈＢ染料分子以及固态的ＲｈＢ染料的Ｒａｍａｎ散射谱。在相同的激发强度下,固态ＲｈＢ染料的Ｒａｍａｎ散射最弱,而镀银的多孔硅表面具有明显的增强效果（～１０＾４）。     

Echo-Planar Imaging of Porous Media with Spatial Resolution below 100 μm

A modified version of the echo-planar imaging technique incorporating a Carr–Purcell train of 180° rf pulses (PEPI) has been implemented on a standard spectrometer. It is demonstrated that artifacts in the image due to cumulative errors in the rf field can be reduced by replacing each 180° pulse by a composite sequence of three rf pulses. Artifact-free 3D images at 94 μm voxel resolution are obtained within 15 min. This technique has been applied to study the drying process in an initially water-saturated model porous medium with characteristicT^*₂of order 700 μs.     

Shapes of heaps and in silos

Experimental investigations on the shape of a heap formed in a Hele Shaw cell either on a flat base or in a two-dimensional silo are presented. We have focused our attention on the shape dependence on mass flux and initial energy of particles poured into the cell. Two kinds of granular media are considered: glass beads and sand and we shall point out their different behaviors. We described the variations of the angle of repose and of the size of the tail as a function of the experimental parameters. We also report the time evolution of the angle of repose during the formation of the heap. Received 28 September 1998 and Received in final form 20 January 1999     

多孔二氧化钛对三氯甲烷光催化氧化的影响

报道 了以多孔 二氧化钛 为光催 化剂光催 化降解 水环境中 三氯甲烷 的一些 结果． 在所选定的实验 条件下 经１５ ｈ 光照, Ｃ Ｈ Ｃｌ３ 光催 化分解率 可达８０ ％ 左右 ． 此 结果 有利 于今 后进 一步 开展实用性 光催化 净化反应 器的研制     

流体饱和多孔介质中波传播问题的有限元分析

采用基于混合物理论的多孔介质模型,给出流体饱和两相多孔介质波动问题的有限元分析方法·　采用罚方法导出的有限元动力方程,时间积分可采用显式和隐式积分两种方案·　用编制的有限元程序分析了一维柱体在跃阶载荷和脉冲载荷作用下的波传播问题,得到该两种瞬态载荷作用下固体和流体相位移、速度以及固体相有效应力和孔隙压力随时间的变化关系,并对波的传播现象进行了分析·　所得结果与理论相吻合·     

GRIN介质用于面内位移的测量

本文把梯度折射率（ＧＲＬＮ）介质的面内位移与其折射率梯度联系起来,对面内位移导致的折射率变化进行研究,介绍了ＧＲＩＮ介质用于面内位移测量的基本原理,给出了双光束干涉法测量悬臂梁挠度的实验方法和实验结果     

双染料复合敏化SnO2纳米多孔膜光电极的研究

光电化学;光电转换;双染料复合敏化SnO2纳米多孔膜光电极的研究     

水相中金属有机化学反应的研究进展

本文综述了近年来水相中金属有机化学反应的研究进展, 讨论了该类反应在反应机理、试剂及立体化学等方面的特点, 以及在天然产物全合成和工业生产等方面的应用。     

Infiltration of Liquid Metals in Porous Compacts: Modeling of Permeabilities During Reactive Melt Infiltration

Reactive infiltration is a fast and cost-effective technique for manufacturing ceramic-matrix composites (CMCs). CMCs are used in elevated temperature applications like rocket engine casings, jet nozzles, gas turbine blades and nuclear cladding. There is an urgent need for minimizing experimental costs as well as optimizing process parameters during manufacture, so that we have minimized manufacturing costs and reduced infiltration times. Towards this end, the objective of this research was to develop an integrated micro-macro model of reactive flow of molten silicon in a porous preform consisting of carbon-coated silicon carbide fibers and then optimize process parameters computationally. The overall objective of the research was to arrive at a modified equation of Darcy's law for flow through a porous medium with the help of numerical/computational modeling. This paper deals with the flow of silicon through porous carbon at the macro level. The macro flow of silicon was integrated with an available micro model by determining the transient porosity from the micro model and using it in Darcy's law written for the macro flow of silicon. From the results of this study, we recommend suitable process parameters such as initial temperature of the solid reactant and the specific kind of reactants to be used for achieving complete infiltration. These conclusions are drawn after observation of the rate of decrease of permeability with more reaction.     

Thermodynamic Automaton Simulations of Fluid Flow and Diffusion in Porous Media

A thermodynamic automaton model of fluid flow in porous media is presented. The model is a nonrelativistic version of a Lorentz invariant lattice gas model constructed by Udey et al. (1998). In the previous model it was shown that the energy momentum tensor and the relativistic Boltzman equation can be rigorously derived from the collision and propagation rules. In the present paper we demonstrate that this nonrelativistic model can be used to accurately simulate well known results involving single phase flow and diffusion in porous media. The simulation results show that (1) one-phase flow simulations in porous media are consistent with Darcy's law; (2) the apparent diffusion coefficient decreases with a decrease in permeability; (3) small scale heterogeneity does not affect diffusion significantly in the cases considered.