Determination of Atrazine,Simazine, Alachlor,and Metolachlor in Surface Water Using Dispersive Pipette Extraction and Gas Chromatography–Mass Spectrometry

Four commonly found pesticides (alachlor, atrazine, metolachlor, and simazine) in surface water were determined using dispersive pipette extraction followed by gas chromatography–mass spectrometry. The rapid mixing and equilibrium between the dispersive pipette extraction adsorbent and water sample resulted in fast and efficient extraction. Using only 5?mL of water sample, the estimated time consumption for extraction of each sample was less than 5?min. Method validation was performed to evaluate accuracy, precision, linearity, the limits of detection, and the limits of quantitation. Average recovery of above 90% was obtained with relative standard deviations below 10%, which indicated good accuracy and precision of the dispersive pipette extraction method. Coefficients of determination were all above 0.9901 and showed good linearity. For the four pesticides studied using the current method, the limits of detection ranged from 7 to 40?ng?L^?1, and limits of quantitation were from 20 to 130?ng?L^?1. Method validation results supported the application of the current method for drinking water safety monitoring per National Primary Drinking Water Regulations established by the US Environmental Protection Agency. Water samples from Lake Lanier and Stone Mountain Lake (Georgia, USS) were analyzed with this method as a preliminary work for a larger scale drinking water quality study in the future. Trace amounts of simazine and atrazine were found in lake water samples, but both were below the regulation levels of the US Environmental Protection Agency.     

Expeditious synthesis of 9-allenylpurines via cesium carbonate catalyzed isomerization of 9-alkynylpurines

An expeditious and convenient method to synthesize 9-allenylpurines via cesium carbonate catalyzed isomerization of 9-alkynylpurines has been successfully developed. The reactions proceeded rapidly under the base conditions and formed the desired products in good to excellent yields. The method was suitable with a broad substrate scope and proceeded well even on a multgram-scale. The obtained 9-allenylpurines were successfully applied to prepare various potential bioactive 9-acyclic nucleosides with high regioselectivity promoted by AgNO₃.     

Hydrolysis of Methylal Catalyzed by Ion Exchange Resins in Aqueous Media

In the present work, the chemical equilibrium and kinetics of methylal (PODE₁) hydrolysis catalyzed by ion–exchange resin in aqueous solutions were investigated. The study covers temperatures between 333.15 and 363.15 K at various starting compositions covering (PODE₁ + MeOH)/water molar ratio ranges from 0.5 to 1.5 in a time scale. On the basis of the experimental results, a mole fraction-based model of the chemical equilibrium and a pseudohomogeneous model are proposed to fit data based on true amount of monomeric formaldehyde. It has been demonstrated that the hydrolysis of PODE1 is slightly endothermic with the enthalpy 8.19 kJ/mol and the rate determining step. Finally, a feed–forward artificial neural networks (ANN) model is developed to model the concentration change of methanol in aqueous solutions. The results showed that the predicted data from designed ANN model were in good agreement with the experimental data with the coefficient (R²) of 0.98. Designed ANN provides a reliable method for modeling the hydrolysis reaction of methylal (PODE1).     

中华鳖(Trionyx sinensis)稚鳖“白点病”的病原菌及其防治的研究

从患“白点病”的病鳖体中分离到四株菌,经人工感染试验,仅一株菌对健康稚鳖表现出较强的致病力。对该菌的形态特征、培养特性和生理、生化反应的鉴定认为：该病原菌是嗜水气单胞菌（Ａｅｒｏｍｏｎａｓｈｙｄｒｏｐｈｉｌａ）应用药敏纸片法研究了２０种化学疗剂对该病原菌的生长抑制作用,结果表明：环丙沙星、氟哌酸、庆大霉素、痢特灵等对病原菌具较强抑制作用,而复方新诺明、头孢拉定、呋喃妥因、麦迪霉素、氨苄青霉素等无抑菌作用．在此基础上进行了药物疗效试验。     

Palladium-catalyzed aminations of aryl halides with phosphine-functionalized imidazolium ligands

A series of 1-(2-diphenylphosphinoferrocenyl)ethyl-3-substituted imidazolium iodides [3-substituent = methyl (1a); isopropyl (1b); tert-butyl (1c); 1-adenosyl (1d); cyclohexyl (1e); 2,6-dimethylphenyl (1f); 2,4,6-trimethylphenyl (1g); 2,6-diisopropylphenyl (1h)] have been prepared and evaluated as ligands in the palladium-catalyzed aminations of aryl halides with various amines. The scope of the coupling process was carried out for various aryl bromides and chlorides with the catalysts generated in situ from a mixture of Pd(OAc)2 and in the presence of a base. NaO t Bu was found the choice of base in combination with dioxane, toluene, or DME as solvent, although NaOH or Cs2CO3 promoted the coupling of 4-bromotoluene with morpholine in moderate conversion. The steric hindrance from the 3-substituent of imidazolium in the hybrid-bidentate chelating system was found to be only beneficial to the substrates without ortho-substituents. The more sterically hindered 1d or 1h promoted the coupling of bromobenzene with morpholine in nearly quantitative conversion with 0.2 mol% of palladium loading in the presence of NaO t Bu at 110 degrees C, and 94% of conversion was afforded with the less sterical demanding 1a for a longer time. However, for the substrates with ortho-substituents, higher conversions were achieved with 1a. The Pd(OAc)2/1d catalytic system was also active for deactivated aryl chloride, and 71% isolated yield for the desired product was realized for coupling of 4-chloroanisole with morpholine at 2 mol% of catalyst loading. The developed catalyst system has been applied successfully to the synthesis of a key building block for a type of functional polymers.     

Synthesis and evaluation of the cytotoxicity of apoptolidinones A and D

Apoptolidins A-D are microbial secondary metabolites shown to be selectively cytotoxic against several cancer cell lines and noncytotoxic against normal cells. Total syntheses of apoptolidinones A and D are reported. The efficient synthetic strategy leading to the apoptolidinones features construction of the common 20-membered macrolactone by an intramolecular Suzuki reaction and stereocontrolled aldol reactions establishing the C19/C20 and C22/C23 stereocenters. In contrast to apoptolidin A, the aglycones apoptolidinone A and D were shown to be noncytotoxic when evaluated against human lung cancer cells (H292).     

Preparation, characterization and in vitro anticancer activity of platinum(II) complexes with N-Cyclohexyl-1,3-propanediamine as the carrier

New JM118 (active form of satraplatin) analogues with N-cyclohexyl-1,3-propanediamine (N-chpda) as the carrier, cis-[Pt(N-chpda)X2] (X2=2Cl(-) (1), oxalate (2), malonate (3), 1,1-cyclobutanedicarboxylate (CBDCA) (3), and 3-hydroxy-1,1-cyclobutanedicarboxylate(HO-CBDCA) (4)), have been synthesized and characterized by elemental analysis and spectroscopic data along with X-ray crystal structure for a representative compound cis-[Pt(N-chpda)Cl2]. The complexes have also been evaluated for their in vitro anticancer activity. All these analytical data are in good agreement with the structures of the desired compounds. The Pt(II) is in a square planar environment and is coordinated by a chelating N-chpda ligand and 2Cl(-) in cis position, and there are two crystallographically independent cis-[Pt(N-chpda)Cl2] molecules linked together by intermolecular N-H...Cl hydrogen bonds. Compounds 1 and 2 are very active against human lung cancer cell line (AGZY) and human lymphocytic leukemia cell line (Raji), and are much more active than carboplatin. Platinum(II) complexes with N-cyclohexyl-1,3-propanediamine is an alternative choice for mixed ammine/aminoplatinum anticancer drugs.     

Ce0.8Gd0.2O1.9制备方法对负载的铂催化剂在异辛烷水蒸气重整制氢过程中抗硫中毒性能的影响

以柠檬酸溶胶-凝胶法、六亚甲基四胺共沉淀法和草酸共沉淀法合成了具有萤石结构的Ce0.8Gd0.2O1.9(CGO)复合氧化物,并用初湿浸润法制备了负载型Pt/CGO催化剂. 纯异辛烷的重整反应结果显示,制得的催化剂均达到了热力学平衡转化. 抗硫测试表明,用柠檬酸溶胶-凝胶法所制载体制备的催化剂具有最好的抗硫中毒性能,在300 ìg穏-1硫存在条件下,100 h内异辛烷均接近完全转化. 用六亚甲基四胺共沉淀法和草酸共沉淀法所制载体制备的催化剂,在相同硫含量条件下,100 h后异辛烷的转化率分别降至～90%和～82%. 这主要是由于二者热稳定性较差和Pt与CGO复合氧化物载体之间相互作用较弱所致. 催化剂储氧量与其抗硫中毒性能并无直接关联. 另外,3种催化剂均具有良好的抗积炭性能.     

The in‐capillary DPPH‐capillary electrophoresis‐the diode array detector combined with reversed‐electrode polarity stacking mode for screening and quantifying major antioxidants in Cuscuta chinensis Lam

An in‐capillary 2, 2‐diphenyl‐1‐picrylhydrazyl (DPPH)‐CE‐the DAD (in‐capillary DPPH‐CE‐DAD) combined with reversed‐electrode polarity stacking mode has been developed to screen and quantify the active antioxidant components of Cuscuta chinensis Lam. The operation parameters were optimized with regard to the pH and concentration of buffer solution, SDS, β‐CDs, organic modifier, as well as separation voltage and temperature. Six antioxidants including chlorogenic acid, p‐coumaric acid, rutin, hyperin, isoquercitrin, and astragalin were screened and the total antioxidant activity of the complex matrix was successfully evaluated based on the decreased peak area of DPPH by the established DPPH‐CE‐DAD method. Sensitivity was enhanced under reversed‐electrode polarity stacking mode and 10‐ to 31‐fold of magnitude improvement in detection sensitivity for each analyte was attained. The results demonstrated that the newly established in‐capillary DPPH‐CE‐DAD method combined with reversed‐electrode polarity stacking mode could integrate sample concentration, the oxidizing reaction, separation, and detection into one capillary to fully automate the system. It was considered a suitable technique for the separation, screening, and determination of trace antioxidants in natural products.     

原子在两个平行镜面间两层电介质板中的自发辐射率

利用光子的闭合轨道理论,我们研究了原子在两个平行镜面间两层电介质板（折射率分别为n1,n2）中的自发辐射率. 自发辐射率呈现出多周期的振荡结构。自发辐射率的傅立叶变换中的每一个峰和光子从原子出发到返回原子的一条闭合轨道相对应。结果表明自发辐射率和两层电介质的宽度和折射率有关。和只有一层电介质的辐射率比较,当两层电介质的折射率n1 和 n2 差别很小时, 两层电介质之间分界面的反射效应可以忽略;但是当二者的差别很大时,发射效应变得非常重要且自发辐射率中的振荡减弱。本文的结果为原子在不同电介质间的自发辐射率的研究提供了新的理解。