炭黑填充聚乙烯材料电阻—温度特性研究

研究了炭黑／聚乙烯导电复合材料的ＰＴＣ特性及在不同条件下的电阻变化。发现ＰＴＣ特性与体积膨胀及聚乙烯晶相的熔融有许多一致性。认为材料的体积膨胀及聚乙烯晶相熔融时炭黑颗粒均匀化扩散导致了电阻随温度上升。在较高温度下，炭黑颗粒在分子链段热运动的推动下会发生相对聚集使电阻不断减小，这是材料出现ＮＴＣ现象的原因。材料总的电阻温度特性是体积膨胀、炭黑向聚乙烯熔融区扩散及相互聚集三个因素共同作用的结果。     

Conductive polyethylene-carbon black composites by elongational-flow injection molding Part 3. Study of the structure and morphology

The morphology and structure of high molecular weight linear polyethylene (M _w 450000) filled with carbon black and processed using molds that introduce an elongational flow component during injection molding has been examined using electron microscopy and x-ray diffraction techniques. The study of fracture surfaces reveals the display of shish-kebabs oriented along the injection direction with segregated longitudinal channels of carbon black particles. Molecular and lamellar changes in orientation are, furthermore, studied across the thickness of the moldings. It is shown that addition of carbon black particles to injection-molded polyethylene induces significant changes in lamellar orientation. Thus, while lamellar overgrowth proceeds perpendicular to the fiber axes within carbon free channels, lamellae grow randomly within carbon-enriched regions where flow is less pronounced.     

Circularly Polarized Absorption Property of Tetra-4[4''''-(2-methylbutoxy)benzoyloxy]phenyl Porphyrin by Introducing Optical Pendant Groups

Circularly polarized luminescent(CPL) materials possess special dissymmetric optical property, i.e. luminescent light having different intensities for left (L) and right(R) circularly polarized components. Recently, these materials have been applied in colour-image projection, stereoscopic displays and light-emitting diodes(LEDS)1-7. We have synthesized a new porphyrin derivative, tetra-4[4'-(2-methylbutoxy)benzoyloxy] phenyl porphyrin [T(MBBP)P], by introducing a chiral group, which p…     

硅钼杂多阴离子薄膜修饰电极线性扫描伏安法测定黑液中可溶性硅

本文报导了以玻碳电极为基体的１：１２硅钼杂多阴离子薄膜化学修铈电极的制备及其电化学特性。并应用于导数伏安法测定。在４．０×１０￣（－３）ｍ０ｌ／Ｌ（ＮＨ＿４）＿６ＭＯ＿７Ｏ＿（２４）－６．８×１０￣（－２）ｍｏｌ／ＬＮａ＿３Ｃｉｔ－０．４８ｍｏｌ／ＬＮＨＯ＿３体系中，硅浓度在８．３×１０￣（－７）～１．７×１０￣（－３）ｍｏｌ／Ｌ范围内与峰电流呈良好线性关系，检测限为８．０×１０￣（－７）ｍｏｌ／Ｌ。对可溶性硅（以ＳｉＯ＿２计）为２４５．０５ｍｇ／Ｌ的黑液，稀释１０倍后，取２．００ｍＬ平行测定９次，ＲＳＤ为０．５８％，加标回收率在９７．３％～１０４．４％间。     

Synthesis and Insulin—sensitizing Activity of a Series of 2—Benzyl—1,3—dicarbonyl Derivatives

A series of 2-benzyl-1,3-dicabonyl derivatives was synthesized.Their insulin-sensitizing activity was evaluated in 3T3-L1 preadipocyte cells.Compounds3,26 and 27 were found to possess strong insulin-sensitizing activity in vitro and were selected for further hypoglycemic evaluation in vivo.     

Expression and Characterization of Catalytic Domain of T Cell Protein Tyrosine Phosphatase（△TC-PTP） —— Immunohistochemical Study of △TC-PTP Expression in Non-small Cell Lung Carcinomas

This study objective was to express and characterize the catalytic domain of the human T cell protein tyrosine phosphatase（△TC-PTP） and to study immunohistochemically the expression of △TC-PTP in human non-small cell lung cancers. △TC-PTP gene was PCR amplified with the cDNA of human TC-PTP as template, and cloned into the pT7 expression vector. The recombinant pT7-△TC-PTP was expressed in E. coli Rosetta （ DE3 ） host cells and puri- fied. The enzymatic characteristics of △TC-PTP including enzyme activity and kinetics assay were measured. The antiserum was prepared by immunizing rabbit with the purified recombinant △TC-PTP. Rabbit polyclonal antibody against △TC-PTP was purified by PVDF immobilized antigen affinity chromatography. Immunohistochemical staining of lung cancer tissues was performed with antibody against △TC-PTP protein. △TC-PTP gene was correctly cloned, expressed, and purified. The recombinant △TC-PTP had a highly catalytic activity of PTPase. Squamous cell lung carcinoma showed a significantly higher expression rate of △TC-PTP （76. 92%, 10/13 ） than adenocarcinoma （57.14%, 4/7） and normal lung tissue（20%, 1/5 ）. This study represents the first demonstration that △TC-PTP is highly expressed in human squamous cell lung carcinomas. In addition, this study provides an important basis for further studying the biological function of TC-PTP and its relationship with lung carcinomas and other diseases.     

Highly efficient synthesis of 2′,3′-didehydro-2′,3′-dideoxy-β-nucleosides through a sulfur-mediated reductive 2′,3′-trans-elimination. From iodomethylcyclopropanes to thiirane analogs

Taking into account the thiophilic properties of iodine, a very simple methodology to achieve 2′,3′-didehydro-2′,3′-dideoxy-β-nucleosides in high yield was performed, using mild, and inexpensive conditions, by means of the treatment of 2′-deoxy-3′,5′-dibenzoyl-2′-iodo-β-nucleoside derivatives with NaHS. The process has shown to be highly dependent of the relative geometry between the iodine atom and the adjacent leaving group. In this way, different essays carried out with pyranose derivatives have concluded in no reaction when the vicinal groups to eliminate do not adopt a trans-diaxial disposition. In addition, the treatment of 2-iodomethyl-cyclopropane-1,1-dicarboxylic acid diethyl ester under the same conditions softly and readily leads to the obtention of a mixture of the expected 2-allyl-malonic acid diethyl ester (as the minor product) and the thiirane derivative 2-thiiranylmethyl-malonic acid diethyl ester (as the major product). In this case, the responsible of the reaction progress are the nucleophilic properties of the sulfur atom rather than the thiophilic character of the iodine atom.     

Cobaltporphyrin‐adsorbed carbon black: highly efficient electrocatalysts for oxygen reduction

meso‐Substituted cobalt porphyrins adsorbed on carbon black were prepared as catalysts for the electroreduction of O₂. The catalyst, which was prepared by using a homogenizer in mixing cobalt tetraethylporphyrin and carbon black, gave rise to electroreduction of O₂ at a remarkably positive potential (E_p = 0.45 V versus saturated calomel electrode (SCE)) and showed a high selectively for the four‐electron reduction (n = 3.8). Electrochemical study and extended X‐ray absorption fine structure (EXAFS) analysis revealed that the adsorbed face‐to‐face dimeric aggregates of cobalt porphyrin molecules were highly efficient catalysts for electroreduction of O₂. Copyright © 2005 John Wiley & Sons, Ltd.     

氧化藏红T褪色催化荧光法测定痕量钒

研究了在酸性介质中柠檬酸存在下，痕量钒（Ｖ）催化溴酸钾氧化藏红Ｔ的褪色反应及其动力学条件，建立了催化荧光测定痕量钒的新方法。催化反应在沸水浴中进行８ｍｉｎ，为假零级反应，反应的表观活化能力为９９．２１ｋＪ／ｍｏｌ，反应速度常数为０．１２／ｓ；该方法的检出限为２．２×１０＾－８ｇ／Ｌ；线性范围为０．２￣２．４μｇ／Ｌ研究了共存离子的影响，用于人发和煤灰中痕量钒的测定，结果令人满意。     

Some developments in reaction and solution microcalorimetry,with particular reference to its use in biochemistry and cellular biology

The field of isothermal microcalorimetry as applied to systems of interest for aqueous solution chemistry, biochemistry and in cellular biology is briefly reviewed. Some techniques recently developed in the author's laboratory are described.