在位分散聚合聚甲基丙烯酸甲酯/二氧化硅纳米复合材料研究

应用在位分散聚合方法制备了分散相粒径介于１３０ｎｍ左右的聚甲基丙烯酸甲酯／二氧化硅ＰＭＭＡ／ＳｉＯ２纳米复合材料，并利用ＳＥＭ，ＤＭＡ，ＴＧＡ等手段研究了该体系的性能．结果表明，经表面处理的ＳｉＯ２无机填料在复合材料基体中分散均匀，界面粘结好．ＳｉＯ２填充粒子的用量对基体的热稳定性，动态力学行为，光学行为以及拉伸强度，弹性模量，断裂伸长率等力学性能都有较大影响     

Synthesis of Polyacrylaminothiourea Chelating Fiber and Properties of Concentration and Separation of Trace Noble Metal Ions from Samples

A novel polyacrylaminothiourea chelating fiber was synthesized simply and rapidly from nitrilon (an acrylonitrile-based synthetic fiber), which was applied to preconcentrate and separate of trace amount of Au(Ⅲ）,Pt(Ⅳ）,Pd(Ⅳ） and Ir (Ⅳ） ions from solution of samples.The analyzed ions can be quantitatively concentrated by the fiber up to a flow rate of 20.0mL/min at pH2, and can also be desorbed with 15 mL of 4mol/L HCl 3% thiourea from the fiber column with recoveries of 96.5%-100%.The chelating fiber can be reused for ten times,the recoveries of these ions are still over 92%,and hundred to thousand times of excess of Fe(Ⅲ）,Al（Ⅲ）,Ca(Ⅱ），Mg（Ⅱ）,Ni(Ⅱ）,Mn（Ⅱ),Cu(Ⅱ），Zn(Ⅱ），and Cd(Ⅱ） cause no interference on the determination of the analyzed ions by inductively-coupled plasma atomic emission spectrometry (ICP-AES).The static saturation adsorption capacities of the fiber for the analytes are in the range of 1.15-2.80mmol/g.The relative standard deviations for the determination of 20.0ng/mL each of Au(Ⅲ）,Pt(Ⅳ）,Pd(Ⅳ）and Ir(Ⅳ） are in the range of 0.7%-3.0%.The recoveries for test from standard additions to real solution samples are between 96% and 100%.The concentration of each ion in powder sample detected by the method is in good agreement with the certified value.     

金汞齐富集冷原子荧光测汞法的研究

本文介绍了一种用于测定汞的金汞齐富集热解系统。研究了该系统与冷原子荧光测汞仪联用的工作条件和干扰,在最佳条件下的检出下限为4×10~(-13)克汞,分析周期3分钟,相对标准偏差2.5%(1.5×10~(-9)克汞)。     

金在脱乙酰壳多糖化学修饰电极上的电化学行为及分析应用

用脱乙酰壳多糖化学修饰电极为工作电极，阳极溶出伏安法测定痕量金。在ｐＨ１～２的ＫＣｌ－ＨＣｌ底液中，起始电位０．２０Ｖ，终止电位１．３０Ｖ，富集时间５ｍｉｎ，以０．１Ｖ／ｓ扫速阳极溶出，峰电位在１．００Ｖ（ｖｓ．ＳＣＥ），Ａｕ（Ⅲ）浓度在０．１０ｍｇ／Ｌ～１０ｍｇ／Ｌ范围内与峰高呈线性关系。在富集１０ｍｉｎ时，可检测０．０２５ｍｇ／ＬＡｕ，大大提高了测定灵敏度，用于矿样测定，无需分离，结果满意。用紫外光谱和拉曼光谱研究了该法的电极过程机理。     

Kinetics and mechanism of gold dissolution in thiourea solutions: Effect of sulfide ions

Chronoamperograms for gold in solutions containing 0.1 M thiourea, 0.5 M H₂SO₄, and catalytically active sulfide ions at the concentration c ₁ from 1 × 10^?5 to 4 × 10^?5 M are obtained at different potentials with the aid of an automated setup intended for renewing the electrode surface directly in the solution by cutting off a thin surface layer of the metal. It is shown that the results of measurements of the current practically coincide at a constant value of the product c ₁ t, where t is the time period elapsed after the renewal of the electrode surface. Such a coincidence testifies to a diffusion nature of processes that hamper accumulation of sulfide ions at the gold surface. This fact permitted the use of a procedure developed previously for the calculation of polarization curves at constant values of surface coverage θ by catalytically active ions. At θ = const, the voltammetric curves for gold in sulfide-containing thiourea solutions are shown to correspond to the Tafel equation. With the surface coverage increasing, the effective values of the exchange current i ₀, transfer coefficient α, and anodic reaction order with respect to thiourea P _a increase from the values i }~ 10^?5 A cm^?2, α }~ 0.12, and P _a = 0.2, which are characteristic of pure solutions, to 2 × 10^?4 A cm^?2, α }~ 0.5, and P _a = 1.1 (at θ }~ 0.5). An interpretation to the established regularities is given.     

Cluster Build-up Reactions using Di-gold Cationic Fragments: Synthesis and Structural Characterization of [Os7(CO)19(Au2dppm)]

The reaction of the di-gold cation [Au₂(dppx)]²⁺ with the heptanuclear cluster dianion [Os₇(CO)₂₀]^2– affords the mixed metal cluster [Os₇(CO)₂₀{Au₂(dppx)}] (x=m (1), e (2), b (3)). On standing, in solution, this complex undergoes decarbonylation to give the cluster [Os₇(CO)₁₉{Au₂(dppx)}] (x=m (4), e (5), b (6)). The complexes have been characterised spectroscopically, and an X-ray structure determination of the dppm derivative shows that it contains a metal core based on an Os₇ edge-bridged bicapped tetrahedron with the two ₃-Au atoms capping adjacent triangular Os₃ faces of the central tetrahedron. In an analogous reaction, the carbido anion [Os₇(H)C(CO)₁₉]^– affords the neutral cluster [Os₇C(CO)₁₉{Au₂(dppm)}] (7) when treated with [Au₂(dppm)]²⁺ in the presence of base.     

Preparation,stability and two-dimensional ordered arrangement of gold nanoparticles capped by surfactants with different chain lengths

Gold nanoparticles modified with C10NH2, C12NH2, C16NH2 and C18NH2 respectively have been prepared by the reverse micelle method. Nanoparticles stability and their two-dimensional (2D) ordered arrangement were studied by UV-Vis absorption spectra and LB technique. The factors, such as the chain length and the size distribution of particles, which affect the 2D ordered arrangement formation, are discussed. Experimental results show that the longer the chain length of surfactants capping the gold nanoparticles, the more stable the nanoparticles, and the more ordered 2D arrangement of gold nanoparticles.