Cr－Ag／γ－Al_2O_3催化剂在CO氧化反应中Ag的助催化作用

Ｃｒ－Ａｇ／γ－Ａｌ_２Ｏ_３催化剂在ＣＯ氧化反应中Ａｇ的助催化作用陈平，朱波，钟依均，罗孟飞，李少华，吴红丽（杭州大学催化研究所杭州３１００２８）（杭州大学中心实验室杭州）关键词氧化铬，氧化银，氧化铝，负载催化剂，还原特性，一氧化碳，氧化活性催化燃烧...     

Synthesis of poly(styrene-co-3-trimethoxysilyl propyl methacrylate) microspheres coated with polysiloxane layer

A procedure has been developed to coat micron-sized poly(styrene-co-3-trimethoxysilyl propyl methacrylate) microspheres with a smooth layer of polysiloxane by the hydrolysis and condensation of methyl trimethoxylsilane (MTMS). Firstly, polystyrene microspheres containing silanol groups were prepared by conventional dispersion polymerization using 3-(trimethoxysilyl) propyl methacrylate (MPS) as a functional comonomer in an ethanol/water medium. Secondly, the synthesis of the polysiloxane shell was carried out using a sol–gel process of MTMS. The thickness of the shells can be easily varied with different copolymer seeds and MTMS feed ratio. When we used copolymer particles with 2.00 μm diameter as seeds, the thickness of the polysiloxane shells can be varied from 0.10 to 0.18 μm. The core/shell structure of the composite microspheres was characterized by transmission electron microscope (TEM).     

几种卟啉在化学还原沉积银膜上的表面增强拉曼光谱特征

应用 Ｊｏｂｉｎ－Ｙｖｏｎ Ｕ—１０００型拉曼光谱仪和ＬＡＢＲＡＭＩ型拉曼光谱系统研究了 ３种卟啉ＴＯＨＰＰ、ＴａｍＰＰ和ＴＳＰＰ在化学还原沉积法制备的银膜上的ＲＳ和ＳＥＲＳ光谱特征。结果表明：化学还原法制备的银膜可以作为这几种卟啉的拉曼增强活性载体。这３种卟啉在获谱的过程中都形成二聚态化合物和发生银离子搀和作用，较长的放置和测谱时间有利于银离子的搀和。     

An analysis of the complex molecular orbitals method

Numerical results for the ground state of the HN ₂ ⁺ and HCO⁺ molecular ions at their near equilibrium geometry, obtained by the complex molecular orbitals (CMO) method in the extended basis set, are reported. The CMO wavefunction of the HN ₂ ⁺ ion is compared with the CI wavefunction obtained in the same basis set. This reveals the nature of approximations inherent in the CMO method. A peculiar feature of the occupation numbers of the CMO natural orbitals is also explained.Alexander von Humboldt Fellow. On leave from the Institute Rudjer Bokovi, Zagreb, Croatia, Yugoslavia.     

Potentiometric Immunosensor Based on Immobilization of Hepatitis B Surface Antibody on Platinum Electrode Modified Silver Colloids and Polyvinyl Butyral as Matrixes

A highly sensitive immunosensor based on immobilization of hepatitis B surface antibody (HBsAb) on platinum electrode (Pt) modified silver colloids and polyvinyl butyral (PVB) as matrixes has been developed for potentiometric immunoanalysis to detect hepatitis B surface antigen (HBsAg) in this study. HBsAb molecules were immobilized successfully on nanometer‐sized silver colloid particles associated with polyvinyl butyral on a platinum electrode surface. The modification procedure was electrochemically monitored by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The HBsAb‐silver‐PVB‐modified electrode exhibited direct electrochemical behavior toward HBsAg. The factors influencing the performance of the resulting immunosensor were studied in detail. More than 94.7% of the results of human serum samples obtained by this method were in agreement with those obtained by enzyme‐linked immunosorbent assays (ELISAs). The resulting immunosensor exhibited a sigmoid curve with log HBsAg concentration, high sensitivity (39.8 mV/decade), wide linear range from 16.0 to 800 ng mL^?1 with a detection limit of 3.6 ng mL^?1, fast potentiometric response (<3 min) and long‐term stability (>4 months). The response mechanism of the immunosensors was also studied with AC impedance techniques.     

Polysulfonylamine. XLI. Ein Silber(I)-Hydrat ungewöhnlicher Zusammensetzung: Röntgenstrukturanalytische und thermochemische Charakterisierung von Tetrakis(dimesylamido)aquatetrasilber(I) [Ag4(N(SO2CH3)2}4(H2O)]

Polysulfonyl Amines. XLI. A Silver(I) Hydrate with an Unusual Composition: Characterization of Tetrakis(dimesylamido)aquatetrasilver(I) [Ag₄(N)SO₂CH₃)₂}₄(H₂O)] by X-Ray Diffraction and Thermal Analysis The title compound is obtained by crystallizing AgN(SO₂CH₃)₂ from water at room temperature. Crystallographic data (at ?95°C): Triclinic space group P1 , a = 864.6(4), b = 1 211.2(5), c = 1 399.1(5) pm, α = 90.97(3), β = 90.90(3), γ = 98.25(4)°, V = 1.4496 nm³, Z = 2, D_x = 2.608 Mg m^?3. The four independent silver atoms and the water molecule form zigzag chains Ag(1)-Ag(2)-(μ-H₂O)-Ag(3) …? Ag(4) …? Ag(1′) with distances Ag(1)-Ag(2) 309.7, Ag(2)-O(w) 241.8, O(w)-Ag(3) 241.4, Ag(3) …? Ag(4) 342.9, Ag(4) …? Ag(1′) 361.4 pm. The catenated silver atoms are further connected by the dimesylamide anions acting as tridentate bridging (α-O, N, ω-O)-ligands. The resulting strands are interconnected into layers through one O(S)-Ag′ contact (247 pm) and one hydrogen bond O(w)-H(l) …? O′(S) per repeating unit. Between the layers, a weak O(S) …? Ag″ interaction (271 ptn) and a hydrogen bond O(w)-H(2) …? O(S) per repeating unit are observed. The silver atoms Ag(l) to Ag(4) display the coordination numbers 5 [NO,Ag(2), distorted trigonal bipyramid], 5[NO₂,O(w)Ag(I), distorted trigonal bipyramid], 5[O₄,O(w), trigonal bipyramid], and 2 + 1 (N₂, li-near; plus a secondary Ag …? 0 contact). The dehydration of the title compound and a solid-solid phase transformation in anhydrous AgN(SO₂CH₃)₂, were quantitatively investigated by thermoconductometry and time- and temperature-resolved X-ray diffractometry (TXRD).     

Ag@Au core/shell triangular nanoplates with dual enzyme-like properties for the colorimetric sensing of glucose

Due to the serious harm of diabetes to human health, development of sensitive assays for glucose level is of high significance for early prevention and treatment of diabetes. Currently, most conventional enzyme-based glucose sensors suffer from high cost and low stability due to the inherent defects of natural enzymes. Herein, we develop a pure nanozyme-based glucose detection method using Ag@Au core/shell triangular nanoplates (TNPs), which combines glucose oxidase (GOD)- and horseradish peroxidase (HRP)-like activities of the Au shell and inherent plasmonic properties of Ag TNPs. The sensing mechanism is based on the fact that the Au shell possessed GOD-like activity, enabling the oxidation of glucose to produce H₂O₂, which can further etch the silver core, leading to the decrease of absorbance at 800 nm and the color change from blue to colorless. Compared with the previous nanozymes-based glucose sensors, our method avoids the use of enzymes and organic chromogenic agent. Moreover, the stability of the Ag@Au core/shell TNPs is much better than that of Ag TNPs due to the protection by the coating of the Au shell. This method was successfully applied to the detection of urine samples from patients with diabetes, indicating its practical applicability for real sample analysis.     

银（Ⅰ）－硫脲－四正丁基溴化铵体系电致化学发光法测定水中痕量银

本文研究了银（Ⅰ）－硫脲－四正丁基溴化铵体系的电致化学发光（ＥＣＬ）。发现在正矩形脉冲下，银对含有硫脲的ＴＢＡＢｒ溶液的ＥＣＬ有明显催化作用，银（Ⅰ）的浓度在１．４×１０￣（－８）～３．５×１０￣（－６）ｍｏｌ／Ｌ范围内与ＥＣＬ强度呈良好线性关系。检出限为９．０×１０￣（－９）ｍｏｌ／Ｌ相对标准偏差为５％。用于天然水中银的测定，获得较满意的结果。     

笼形聚偕氨肟树脂的研究──Ag(Ⅰ)在树脂上的吸附过程

测定了Ag+离子在笼形聚偕胺肟树脂（CAO）及其酸、碱处理产物（ACAO、BCAO）上的吸附容量．Ag+离子在BCAO树脂上吸附容量较高,但同非选择性吸附,在ACAO上的吸附容量则与处理树脂的酸的pKa值有关．用高pKa值的硼酸、苯酸和对氨基酚处理所得的ACAO树脂的吸附容量接近BCAO树脂的水平,认为是胶后胺肟基发生互变异构所致．吸附动力学表明Ag+离子在H3BO3/ACAO和C6H5OH/ACAO树脂上进行多层吸附．在吸附中伴随有氧化还原反应并生成Ag（O）微晶的过程．     

Side effects in measurements of selectivity coefficients of solid state ion selective electrodes

The influence of various factors such as solubility, the oxidation of the membrane, and the contamination of the solution, on the experimental values of the selectivity coefficients of solid state sulphide ion selective electrodes is discussed. A new method for the evaluation of very small selectivity coefficients, based on the addition of reagents forming complexes or insoluble salts with the main ion, is proposed. By means of this method, selectivity coefficients for silver, copper, cadmium and lead ion selective electrodes have been determined, which are in far better agreement with thermodynamic values than those described in the literature.