Synthesis of 4″-benzyloxyimino-4″-deoxyavermectin Bla derivatives

Six new 4″-benzyloxyimino-4″-deoxyavermectin Bla derivatives were synthesized from avermectin Bla by the selective protection of C-5-hydroxy group,oxidation of C-4″-hydroxy group,and deprotection followed by reaction with O-substituted hydroxylamine hydrochlorides.Their structures were confirmed by IR,~1H NMR,~(13)C NMR and MS.Insecticidal activities of the derivatives against Phopalosiphum pseudobrassicae,Spodoptera exigua and Pluteua xylosteua were evaluated.     

Catalytic Adsorptive Stripping Voltammetry of Germanium(IV) in the Presence of Gallic Acid and Vanadium(IV)‐EDTA

A highly sensitive and selective catalytic adsorptive cathodic striping procedure for the determination of trace germanium is presented. The method is based on adsorptive accumulation of the Ge(IV)‐gallic acid (GA) complex onto a hanging mercury drop electrode, followed by reduction of the adsorbed species. The reduction current is enhanced catalytically by addition of vanadium(IV)‐EDTA. The optimal experimental conditions include the use of 0.03 mol/L HClO₄ (pH1.6), 6.0×10^?3 mol/L GA, 3.0×10^?3 mol/L V(IV), 4.0×10^?3 mol/L EDTA, an accumulation potential of ?0.10 V(vs. Ag/AgCl), an accumulation time of 120 s and a differential pulse potential scan mode. The peak current is proportional to the concentration of Ge(IV) over the range of 3.0×10^?11 to 1.0×10^?8 mol/L and the detection limit is 2×10^?11 mol/L for a 120 s adsorption time. The relative standard deviation at 5.0×10^?10 mol/L level is 3.1%. No serious interferences were found. The method was applied to the determination of germanium in ore, mineral water and vegetable samples with satisfactory results.     

Yb2O3对TiO2/(O''+β'')-Sialon复相陶瓷中TiO2相变的影响

以纳米锐钛矿型TiO2粉和（O＇＋β＇）-Sialon粉为原料制备出了TiO2／（O＇＋β＇）-Sialon复相陶瓷，研究了Yb2O3添加剂对材料中锐钛矿型TiO2相变的影响，对其影响机制进行了探讨。采用XRD对材料进行物相组成和晶格参数表征。结果表明，Yb2O3对锐钛矿相变开始温度无明显影响，但对相变有显著的促进作用，随添加量的增加，其作用逐渐减弱。添加的Yb2O3同时以两种形式存在：一部分进入TiO2晶格，一部分堆积在TiO2晶粒表面。Yb^n＋进入TiO2晶格置换Ti^4＋和Yb^3＋与TiO2发生氧化还原反应促进相变，而存在于TiO2表面的Yb^3＋与TiO2相互作用形成Ti-O-Yb键而抑制相变。Yb2O3对锐钛矿相变的影响是这两方面机制共同作用的结果。     

二甲苯在AlPO4-5分子筛中吸附的分子模拟研究

采用巨正则蒙特卡罗法(GCMC)研究了二甲苯异构体在AlPO4-5中的吸附，得到了有关吸附平衡常数、吸附热、吸附等温线及吸附位等信息．结果表明，在303K时，邻二甲苯的吸附量高于其它异构体；而在523和573K时，对二甲苯的吸附量最高．低吸附量时二甲苯的平均势能基本不发生变化，而高吸附量时二甲苯的平均势能随着吸附量增加而降低，尤其邻二甲苯的平均势能变化更加明显．由此对二甲苯各异构体在AlPO4-5中的吸附量差别以及它们在分子筛中的排列方式进行了讨论．     

Synthesis and Crystal Structures of Novel Keggin and Dawson Polyoxometalates Containing Amantadine

Heteropolyoxometalates are a large family of potent medicines due to their excellent antiviral and antitumor activity 1-4, while their application in clinic meets great difficulties for their toxicity 5. How to synthesize heteropolyoxometalate medicines possessing high activity and low toxicity has become the focus in heteropolyoxometalate medicine research. Previously reported polyoxometalates showing medical activities are all salts simple Na+, K+ or NH4+ etc. inorganic cations, in which o…     

Preparation and characterization O-lauroyl chitosan/poly (L-lactic acid) blend membranes by solution-casting approach

O-Lauroyl chitosan/poly(L-lactide) (OCS/PLLA) blend membranes with different compositions were prepared by solution-casting approach using chloroform as common solvent. The experimental results of FT-IR, DSC and WAXD indicated that inter-association hydrogen-bond interactions existed between OCS and PLLA in the blend membranes. And SEM observation confirmed that the blend membranes with suitable compositions were compatible.     

Heat shock protein 27 interacts with vimentin and prevents insolubilization of vimentin subunits induced by cadmium

Vimentin is an intermediate filament that regulates cell attachment and subcellular organization. In this study, vimentin filaments were morphologically altered, and its soluble subunits were rapidly reduced via cadmium chloride treatment. Cadmium chloride stimulated three major mitogen-activated protein kinases (MAPKs): extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38, and led apoptotic pathway via caspase-9 and caspase-3 activations. In order to determine whether MAPKs were involved in this cadmium-induced soluble vimentin disappearance, we applied MAPK-specific inhibitors (PD98059, SP600125, SB203580). These inhibitors did not abolish the cadmium-induced soluble vimentin disappearance. Caspase and proteosome degradation pathway were also not involved in soluble vimentin disappearance. When we observed vimentin levels in soluble and insoluble fractions, soluble vimentin subunits shifted to an insoluble fraction. As we discovered that heat-shock protein 27 (HSP27) was colocalized and physically associated with vimentin in unstressed cells, the roles of HSP27 with regard to vimentin were assessed. HSP27-overexpressing cells prevented morphological alterations of the vimentin filaments, as well as reductions of soluble vimentin, in the cadmium-treated cells. Moreover, HSP27 antisense oligonucleotide augmented these cadmium-induced changes in vimentin. These findings indicate that HSP27 prevents disruption of the vimentin intermediate filament networks and soluble vimentin disappearance, by virtue of its physical interaction with vimentin in cadmium-treated SK-N-SH cells.     

基于天然氨基酸的双环手性季铵盐相转移催化剂的合成及催化性能研究

以L－脯氨酸及L－羟基脯氨酸为原料合成了4个新型手性季铵盐磁相转移催化 剂，并用于催化不对称查耳酮环氧化反应，高产率得到相应环氧化合物，ee最高达 9％。     

Capillary electrophoresis with end-column amperometric detection of urinary 8-hydroxy-2'-deoxyguanosine

Urinary 8-hydroxy-2'-deoxyguanosine (8OHdG) is an excellent marker of oxidative DNA damage. Until now, urinary 8OHdG has been measured by high-performance liquid chromatography with electrochemical detection. A simple and sensitive method for the analysis of urinary 8OHdG by capillary electrophoresis with end-column amperometric detection has been developed in our laboratory. A single-step solid-phase extraction procedure was optimized and used for extracting 8OHdG from human urine. To improve the sensitivity of this method, a new focusing technique based on a dynamic pH junction was used. The limit of detection was 20 nM (signal-to-noise ratio S/N = 3), the linear range was 50 nM-10 microM, and the correlation coefficient was better than 0.999. The relative standard deviation (RSD) was found to be 0.57% for migration time, and 4.79% for peak current. To show the usefulness of the method, the urinary concentration of 8OHdG in nine healthy persons and ten cancer patients was determined. The urinary concentration of 8OHdG in cancer patients was significantly higher than that in healthy persons.     

有序自组装聚合物纳米结构

采用水辅助方法(water-assisted fabrication method),分别以4-十二烷基苯磺酸掺杂的聚苯胺(PANI-DBSA)和聚2-甲氧基-5-(2′-乙烯基-己氧基)苯乙炔(MEH-PPV)两种功能高聚物为成膜材料,冷凝水滴为模板,利用水滴在聚合物溶液表面的自组装,制备出了两种纳米层次以上的蜂窝状有序多孔聚合物薄膜.通过原子力显微镜和共聚焦荧光显微镜对其形貌、电学性质和荧光图像进行了表征.