高效液相色谱法分析茶叶中吡虫啉残留量

吡虫啉（Imidacloprid）中文通用名为咪蚜胶，属硝基亚甲基类内吸性低毒杀虫剂。其作用是选择性抑制昆虫神经系统中的烟酸乙酰胆碱脂酶受体，从而破坏昆虫的中枢神经的正常传导，使之神经麻痹后死亡，在农产品种植过程中用于防治刺吸式口器害虫。它对黑尾叶蝉、飞虱类、蚜虫类和蓟马类有优异的防效作用，效果优于噻嗪酮、醚菊酯、抗蚜威和杀螟丹等农药，因此，近年来被广泛用于茶叶生产上。     

PEG-related polymer resins as synthetic supports

Combinatorial chemistry has become a significant part of the discovery and optimization process for novel drugs, affinity ligands, and catalysts. The polymeric supports play a key role in combinatory chemistry. Therefore, various kinds of functional polymer resins have been exploited as supports, reagents, and catalysts in organic synthesis. In comparison to the conventional Merrifield resins, the poly(ethylene glycol) (PEG)-related polymer resins have advantages including good compatibilities with polar solvents, good solvent absorbency and swelling properties. This review focuses primarily on the more recent work in the field of developing PEG-related polymer resins as supports for organic synthesis.     

PEG化的聚合物载体树脂研究进展

组合化学已成为发现和优化新药、亲和配体和催化过程中的重要组成部分.高分子载体树脂在组合化学中起着关键的作用,各种类型的聚合物树脂在有机合成中已被广泛开发为载体、反应物和催化剂.与传统的Merrifield树脂相比较,聚乙二醇(PEG)化的聚合物树脂具有与极性溶剂更好的相容性、更高的溶剂吸收和溶胀性能.本文主要综述与PEG相关联的聚合物树脂在有机合成载体领域中的最新成果.     

Global existence and decay of smooth solutions for the 3-D MHD-type equations without magnetic diffusion

We study the large time behavior of a 3-D MHD (magneto-hydrodynamical)-type system without magnetic diffusion introduced by Lin and Zhang (2014). By using the elementary energy method and interpolation technique, we prove the global existence and decay estimate of smooth solution near the equilibrium state (x3, 0).     

Simultaneous determination of components in preparation Naodesheng injection by high performance liquid chromatograph-atmospheric pressure chemical ionization mass spectrometry (HPLC-MS/APCI)

A high-performance liquid chromatograph with mass spectrum detection (HPLC-MS/APCI) method has been established for simultaneous determination of ten major bioactive components of Naodesheng injection including safflor yellow A, puerarin, daidzein, ginsenosides (Rg1, Rg2, Rb1, Rd, Re, Rh1), and notoginsenoside R1. The separations were carried out with a Luna C18 column (5 microm, 150x4.6 mm, Phenomenex, U.S.A.) with a stepwise gradient elution of the mobile phase consisting of water (0.1% of formic acid, v/v)-methanol (0 min, 70:30; 8 min, 30:70; 20 min, 10:90) at a flow-rate of 0.8 ml/min. The proposed method was applied to analyze five various Naodesheng injections and produced data with acceptable linearity, repeatability, precision and accuracy having lower limits of quantitation (LLOQs) of 0.02-0.2 microg. The calibration curves were linear in respective range for all compounds, all of them with coefficients of determination above 0.9900. The intraday precessions were less than 5.0%. The proposed method is accurate, sensitive and simple, a useful alternative for routine analysis in the quality control of Traditional Chinese Medicine.     

Low temperature preparation of flower-like BiOCl film and its photocatalytic activity

The BiOCl thin film with flower-like sphere structure was prepared at a low temperature by the alcoholysis-coating method using BiCl 3 as precursor. The obtained thin film was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), electronic energy spectrum (EDS) and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). And the results showed that the obtained BiOCl film without calcination was composed of flower-like sphere structure with tetragonal phase and had a good absorption for ultraviolet. The photocatalytic activity of BiOCl thin film was also evaluated by the degradation of methyl orange in water under UV light irradiation. The degradation experimental results confirmed that the film prepared at low temperature possessed a high photocatalytic activity and could achieve 97% degradation to 10 mg/L methyl orange solution after 150 min UV light irradiation. The stability of the obtained BiOCl thin film was also good and its photocatalytic activity still remained an above 94% removal of methyl orange after being used four times. In addition, a possible formation mechanism of BiOCl thin film was also inferred and the results suggested that the ethylene glycol solvent may contribute to the forming flower-like sphere structure.     

气相中Cu+和Zn+与CS2反应的计算研究

以Cu⁺和Zn⁺与CS₂反应作为第一过渡金属离子与CS₂反应的范例体系. 采用密度泛函UB3LYP/6-311+G^*方法计算研究了第一过渡金属离子在基态和激发态与CS₂反应的反应机理. 全参数优化了反应势能面上各驻点的几何构型, 用频率分析方法和内禀反应坐标(IRC)方法对过渡态进行了验证. 并用UCCSD(T)/6-311G^*方法对各驻点作了单点能量校正. 在Cu⁺与CS₂反应中, 计算了单重态初始中间体¹IM1到三重态插入型中间体³IM2的反应交叉势能面. 确定了第一过渡金属离子与CS₂的反应为插入-消去反应, 找到了基态和激发态金属离子与CS₂反应的主要通道.     

聚合物纳米球结晶机理的计算机模拟

本文基于位置有序参数(SOP)分析了利用图形处理器(GPU)加速的分子动力学程序GMD模拟含有4.5万和36万个CH2联合原子的聚乙烯纳米球的分子动力学结晶过程中结晶度的变化,并使用Avrami方程得到了不同温度下的结晶指数.与一般实验结果相同,该指数n不为整数.我们提出了二元混合模型,认为纳米线团的结晶行为由两种机理按一定比例组成.当结晶温度升高时,两种尺寸的纳米线团的Avrami指数均升高并接近4,结晶机理趋向三维生长和均相成核.当温度低时,晶核多在接近纳米球的表面生成,Avrami指数趋近于1.我们对体系结晶成核阶段结束时晶核沿纳米球的径向分布进行了分析.结果表明Tn=0.60时晶核的生成位置接近表面,而Tn=0.68时晶核出现一个接近纳米球内部的峰.该结果与二元混合模型的Avrami指数的分析结果相吻合.     

超高温压电陶瓷CaBi2Nb2O9的定向生长及性能

将熔盐法制备的片状CaBi2Nb2O9（CBNO）前驱体在1050℃烧结成陶瓷,对陶瓷晶粒取向和形貌进行了分析和表征,研究了其介电、铁电和压电性能.与传统固相法制备的样品相比较,新工艺制备出的CaBi2Nb2O9陶瓷,烧结温度降低,晶粒定向生长,具有明显织构特征,室温时极化变得容易,介电损耗减小,压电系数明显提高.     

花球状BiOCl薄膜的低温制备及其光催化性能

以BiCl3为原料,采用醇解．涂覆法在相对较低的温度下制备了具有花球状微观形貌的BiOCl薄膜．采用X射线衍射谱（XRD）、扫描电子显微镜（SEM）、电子能量散射谱（EDS）和紫外-可见漫反射光谱（DRS）对所制薄膜进行了晶相、形貌、元素组成和光学性质表征,并以甲基橙为目标降解物,研究了薄膜的光催化性能．分析结果表明：BiOCl薄膜具有四方晶相结构,薄膜呈花球状微观形貌,对紫外光有良好的吸收．降解实验结果表明：未经过高温焙烧的BiOCl薄膜具有较佳光催化活性,经紫外光照射150min后对甲基橙的降解率达97％,且具有较高的光催化稳定性,重复使用4次后对甲基橙的降解率仍保持94％以上．此外,文中还对BiOCl薄膜的形成机理做了推测．