A new approach to qualitative analysis of organophosphorus pesticide residues in cucumber using a double gas chromatographic system: GC-pulsed-flame photometry and retention time locking GC-mass spectrometry

A qualitative method for the screening of organophosphorus pesticides (OPs) that could present in different types of vegetables has been established and validated. A typical multi-residue extraction procedure of OPs using ethyl acetate and sodium sulphate has been applied. No clean-up was required after extraction, and concentrated extracts were analysed by gas chromatography with pulsed-flame photometric detection (GC-PFPD). Confirmation of compound identities was performed by gas chromatography with mass spectrometric detection (GC-MSD) in the electron impact (EI) mode with full scan acquisition. Retention time locking (RTL) software was used in order to improve the method capability of identification and confirmation. Spiked samples at pesticide concentrations equal to the maximum residue level (MRL) were used to check chromatographic performance and for validation studies. The proposed method allows a rapid and accurate identification of the studied OPs until the ng ml(-1) range for those whose use is forbidden, and above their MRL concentration for the rest.     

4-羟基联苯4’-甲酸-L-2-甲基丁醇酯的合成

以4-羟基联苯，4-羟基4’-氰基联苯和手性L-2-甲基丁醇为原料，通过三条路线合成了铁电性液晶中间体4-羟基联苯4’-甲酸-L-2-甲基丁醇酯。5步法（醚化、酰化、溴仿、水解和酯化）总收率35．6％；3步法（酰化、溴仿和酯化）总收率50．7％；而以4-羟基-4＇-氰基联苯为原料的一步合成法收率64．4％。中间体和目标产物的结构经^1H NNR和IR确证。     

Preparation ,Structural Characterization and Luminescent Property of Binucleasr Silver（Ⅰ）Complex Formed by Benzotriazole and 1—Hydroxymethyl Benzotriazole

Dinuclear silver (I) six‐membered ring complex [Ag₂ (bta)₂ ‐(hmbta)₂] (ClO₄)₂ (3) has been synthesized by the reaction of benzotriazole (bta) (1) and 1‐hydroxymethyl benzotriazole (hmbta) (2) with Ag (CH₃CN)₄ClO₄. The structures of compound 2 and Complex 3 have been studied by single crystal X‐ray diffraction analysis. The change of luminescent intensity of 1, 2 and 3 was reported. Compound 2 crystallizes in the monoclinic system with space group P2 (1)/c, a = 0.7655 (10) nm, b = 1.0126 (14) nm, c =0.9502 (13) nm, β = 95.07 (2)°, V = 0.7337 (17) nm³ and Z = 4. Complex 3 crystallizes in the triclinic system with space group P1, a = 0.73611 (18) nm, b = 0.9152 (2) nm, c = 1.2277 (3) nm, β = 87.170 (5)°, V = 0.8221 (3) nm³ and Z = 1. The main structural feature of complex 3 is a symmetric dinuclear six‐membered ring formed by two silver (I) atoms and four N‐atoms from two benzotriazoles. The second structural feature of complex 3 is the τ‐τ stacking interaction between two adjacent molecular planes, which forms the two‐dimentional layer structure. Besides, compared with 2, the luminescent intensity of complex 3 shows a remarkable enhancement.     

负载型非晶态Cu/SiO2催化剂的非晶性质

以超细ＳｉＯ２为载体，用ＫＢＨ４还原Ｃｕ＾２＋盐溶液制备了非负载型Ｃｕ和负载型Ｃｕ／ＳｉＯ２催化剂，ＸＲＤ，ＴＥＭ和电子衍射分析结果表明，负载型Ｃｕ／ＳｉＯ２为完全非晶态，而非负载型Ｃｕ中存在着少量晶态Ｃｕ，ＤＳＣ结果表明，非晶态Ｃｕ／ＳｉＯ２的热稳定性明显高于非负载型Ｃｕ，说明超细ＳｉＯ２具有稳定非晶结构的作用，ＸＰＳ结果表明，还原产物中的铜原子呈Ｃｕ状态，ＩＣＰ分析结果表明，样品中的Ｂ含量均低     

Self-assembled multivalent vancomycin on cell surfaces against vancomycin-resistant enterococci (VRE)

A vancomycin (Van) derivative self-assembles in a phosphate buffer as a divalent Van and on cell surfaces as a multivalent Van, which offers potent activity against VRE.     

邻菲啰啉对固定尿酸酶催化反应动力学的影响

The activation energy of the enzyme-catalyzed reaction for uric acid decreases markedly in the presence of o-phenanthroline, which activates the bioelectrochemicla activity of the polypyrrole uricase electrode. The response current of the enzyme electrodeis independent of the concentration of o-phenanthroline. Based on the experimental results, the mechamsm of the enzyme-catalyzed reaction for uric acid in the presence of o-phenanthroline is presented as follows: E+A→EA, EA+S EAS, EAS→EA+P, where E, A, S and P are the enzyme, activator, substrate and product, respectively. The effects of pH value, potential and the uric acid concentration on the response currents of the uricase electrode have been studied in the presence of o-phenanthroline. In the presence of o-phenanthroline, the response current of the enzyme electrode increase linearly with increasing concentration of uric acid in the region of 0.07 to 0.67 mmol·L~(-1), therefore the polypyrrole uricase electrode which has once lost its activity can be activated and used again to determine the substrate concentration.     

CuO-BaO/SiO2催化剂的结构表征

以XRD、XPS和EXAFS手段对CuO－BaO／Sic2催化剂及其还原态的结构进行了研究．结果表明，在CuO－BaO／SiO2体系中铜和钡都是以氧化态的形式存在，超细SiO2载体对所负载的CuO的结构有影响．随着样品负载量的逐渐降低，Cu－O和Cu－Cu睡的健长和配位数逐渐征小，而且低载量样品的健长和配位数减小的幅度最大．在总负载量＞13．39％的样品中，CuO以晶相的形式存在；总负载量＜13．39％的样品中，CUO呈现单层分布的高分出状态．还原态样品中钢以本价铜的形式存在，随负载量的降低，还原态Cu－Cu健的镇长和配位数也分别呈现出逐渐减小的趋势．还原态中心铜原子在催化剂表面的分布状态基本上保持了氧化态催化剂中CuO物相的分市状态．     

聚邻甲苯胺的合成及物理化学性质

聚苯胺的导电性和电化学特性已被广泛地研究。最近,对苯胺衍生物的聚合物也开始了研究,如聚邻甲氧基苯胺、聚邻苯二胺和聚邻氨基酚,其中聚邻甲氧基苯胺是一种可溶性的导电高分子材料。为了探讨苯胺聚合的机理和苯胺上不同基团对聚苯胺性质的影响,我们使用了十六种苯     

Kinetic study in water-ethylene glycol cationic, zwitterionic, nonionic, and anionic micellar solutions

The spontaneous hydrolysis of phenyl chloroformate was studied in water-ethylene glycol, EG, cationic, zwitterionic, nonionic, and anionic micellar solutions, the surfactants being tetradecyltrimethylammonium bromide, tetradecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate, tricosaoxyethylene glycol ether, and sodium dodecyl sulfate. The dependence of the observed rate constant on surfactant concentration as well as on the percentage by weight of EG, varying from 0 to 50 wt %, was investigated. Information about changes in the critical micelle concentrations, in the micellar ionization degrees (for ionic surfactants), in the aggregation numbers, and in the polarity of the interfacial region of the micelles upon changing the weight percent of EG was obtained through conductivity, surface tension, spectroscopic, and fluorescence measurements. A simple pseudophase model was adequate to rationalize the kinetic data. Micellar medium effects were explained by considering charge-charge interactions and polarity, ionic strength, and water content in the micellar interfacial region. The acceleration of the reaction produced by an increase in the amount of EG present in the mixture was explained on the basis of the substantial decrease in the equilibrium binding constant of phenyl chloroformate molecules to the micelles, resulting in the contribution of the reaction taking place in the bulk water-EG phase being more important. The weight percent of EG did not substantially influence the rate constant in the micellar pseudophase.     

活性炭自溶液吸附锌(II)离子及其配合物

近年来，有人提出通过表面处理提高活性炭表面电荷，加强对无机离子吸附力等观点，但活性炭对无机离子的吸附活性点，表面含氧基团及配体对吸附的影响等重要问题仍众说纷经[1－4]为此，本文提出用氧化一负离子化法处理活性炭，以表面酸度表征表面含氧基团的量，探讨活性炭对Zn（Ⅱ）及其配合物的吸附特性．1试验（1）试验材料活性发由北京光华木材厂出品，分析纯．过20－30目，BET法测得比表面为1316m2·g-1．在2．5×10－2mlo·dm－3的NaNO3中，测得等电点pHIEP为7．75[5]，元素含量（质量分数）为C（83．9％），N（0．07％），H（1…