Preparation of functional composite grafted particles PDMAEMA/SiO2 and preliminarily study on functionality

Micron-sized silica gel particles were first surface-modified with coupling agent, γ-methacryloylpropyl trimethoxysilane (MPS), and the polymerizable double bonds were introduced onto the surfaces of silica gel particles, forming the modified particles MPS-SiO₂. Subsequently, N,N-dimethylaminoethyl methacrylate (DMAEMA) was graft-polymerized on the surfaces of particles MPS-SiO₂ in the manner of “grafting through”, resulting in the grafted particles PDMAEMA/SiO₂. The grafted particles PDMAEMA/SiO₂ were fully characterized with several means. The graft polymerization process of DMAEMA on particles MPS-SiO₂ was studied in detail, and the optimal reaction conditions were determined. Thereafter, the adsorption properties of the grafted particles PDMAEMA/SiO₂ for chromate anion and Cu²⁺ ion were preliminarily examined respectively. The experimental results indicate that the PDMAEMA grafting degree on PDMAEMA/SiO₂ particles is limited because an enwinding polymer layer as a kinetic barrier on the surfaces of silica gel particles will be formed during the graft polymerization, and blocks the graft polymerization. In order to enhance PDMAEMA grafting degree, reaction time and temperature, and the used amount of initiator as well as the monomer concentration should be effectively controlled. The preliminary adsorption tests show that the grafted particles PDMAEMA/SiO₂ are multi-functional. They possess very strong adsorption ability for CrO₄²⁻ anion by right of strong electrostatic interaction, and have also adsorption action towards heavy metal ion by dint of complexing action.     

Local Thermodynamic Equilibrium for some Stochastic Models of Hamiltonian Origin

We consider a class of 1-D stochastic models that are realizations of Hamiltonian models of heat conduction and prove that in the infinite volume limit local thermodynamic equilibrium is attained with linear energy profile.     

The Formation of Porous Membranes by Filtration of Aerosol Nanoparticles

Flame-generated aerosol particles of Al₂O₃ were deposited by gas filtration on two types of porous and ceramic tubes of -Al₂O₃ with mean pore diameters of 450 and 2700nm, respectively. The particles were aggregates with average mobility diameters in the range of 30–100nm and primary particle diameters of 4–8nm. The particles are characterized by differential mobility analysis, transmission electron microscopy, and by their specific surface area. The deposited membranes are characterized by gas permeability measurements, scanning electron microscopy, and by their pore size distribution from nitrogen capillary condensation. The particles form a distinct, homogeneous membrane layer with a porosity of 90% on top of the substrate surface and only penetrate slightly into the substrate structure. The mean pore sizes of the deposited membranes determined by nitrogen condensation agree approximately with those determined by gas permeation and the specific surface area. The mean pore diameter varies in the range of 30–70nm. The gas permeability of the deposited membranes is related to the specific surface area but influenced by the high porosity. The mean pore size and the permeability of the membranes are almost independent of the substrate structure.The development of a membrane with uniform properties is preceded by a short initial period in which the deposited particles, with an equivalent membrane thickness of roughly 2m, have a significantly lower permeability than the ultimately developed uniform membrane layer. This effect is particularly significant for the aerosol particles with the lowest mean size, probably due to particles deposited in the pore mouths of the substrate.The particles and the deposited membranes are X-ray amorphous but retain their specific surface area on heating to even high temperatures. When the membranes are heated to 1473K for 10h, X-ray diffraction shows a mixture of - and -alumina, accompanied by a partial disintegration of the membrane and a considerable loss of surface area.     

μ子寿命测量实验

根据粒子的平均寿命测量原理,采用大面积塑料闪烁探测器和可编程逻辑器件设计了宇宙线μ子寿命测量的实验教学装置,使用该装置可实现对宇宙μ子寿命的直接测量.通过该实验,可使学生对高能物理理论、高能粒子探测器、高能粒子探测技术和数据获取、处理有整体的理解和认识.本文从实验教学内容和教学方法上对μ子寿命测量实验进行了探讨.     

光学粒子尺寸及其它参量测量的新方法

介绍最近发展起来的三种主要的粒子尺寸及其它参量的光学测量方法,较详细地说明了相位多谱勒法、基于衍射的短阵迭代和积分变换法、测量散射短阵元的分析方法的测量原理和实现方法,对各方法的主要特点进行了讨论。     

High Speed Image Acquisition ＆ Neutral Particle Count Systems and the RTX Research

In HL-2A tokamak experiment, high speed image acquisitoin system grabs images and shows them in real-time. It provides serial images of discharge to help scientists a lot to analyse the experiment. Neutral particle count system counts the number of neutral particles radiated from fusion plasmas. It provides the data to calculate the ion energy.     

Study of compound particle production in 84Kr-emulsion interactions at 1.7 A GeV

The characteristics of compound particle multiplicity distribution and multiplicity correlations between the compound particle and the grey particle, black particle, shower particle and heavily ionized track particle are investigated in this paper. It is found that the average multiplicities of the grey particle, black particle, shower particle and heavily ionized track particle increase with an increase in the number of compound particles, which can be explained by the impact geometrical model. The compound multiplicity distribution is observed to obey a Koba-Nielson-Olesen (KNO) type of scaling law.     

HL-1装置离子温度的电荷交换法测定

本文叙述了用自己研制的六道中性粒子分析器(即中性粒子谱仪),测量HL-1托卡马克装置离子温度的实验,给出了在1986年进行的一组放电实验所得等离子体的离子温度及其随放电时间变化的结果,测得的中心离子温度的典型值为474eV,在相应等离子体参数下,Artsimovich经验公式给出450eV     

用快波加热燃烧等离子体

在把离子伯恩斯坦波处理成对快阿尔芬波的响应下，导出了点火托卡马克等离子体的离子回旋共振加热的二阶模转换方程。这个二阶方程的数值积分表明，结果与由高阶方程的计算很好地一致。只有在弱阻尼的情况下，α粒子吸收的功率才是重要的。     

一次强沙尘暴长距离输送的数值模拟研究

利用HYSPLIT-4传输,扩散模式对2003年4月9日发生在我国西北的强沙尘暴进行长距离输送的数值模拟研究,并进行轨迹和浓度分析.研究结果表明:(1)2003年4月9日强沙尘暴过程的沙尘来源并非某单一地区;(2)此次沙尘暴长距离输送过程中,主要有两个高浓度中心向东传输.一个在北纬35度附近,主要在1 500～3000m高空传输,另一个在北纬40度附近,且主要在1 500m以下传输.后期两者合二为一.