Unusual Transport Properties near the Insulator-Metal Transition in Colossal Magnetoresistive Manganites

It is argued that a combination of the Griffiths theory and the double-exchange mechanism predicts the random distribution of ferromagnetic metallic clusters above the Curie temperature TC in colossal magnetoresistive manganites. Along this line, we propose a model for the temperature dependence of resistivity that yields a quantitative agreement with experimental data obtained in a typical manganite La2/3Ca1/3MnO3. Our result indicates that the formation and growth of ferromagnetic metallic clusters are responsible for the observation of unusual transport properties near the insulator-metal transition.     

STUDY ON STYRENE-BUTADIENE BLOCK COPOLYMER FOR THE MODIFICATI0N OF TIRE TREAD

This paper mainly deals with the design and synthesis of a novel styrene-butadieneblock copolymer. When this copolymer is used in the tread portion of tyres, it can improvewet skid resistance and reduce rolling resistance without sacrificing its general physical-mechanical properties. The visco-elastic curve of tire tread using the novel copolymer asits rubber portion was showed. Reactivity ratios for two monomers in the polymerizingsystem were calculated. The diagrams of differelitial, integral and finite difference calculithroughout the whole molecular chain were presented. The influence of the micro- andmacro-structure of the copolymer chain on wet skid resistance and rolling resistance wasdiscussed     

BaFClxGBr1—X：Sm体系的热释发光及其归属讨论

通过对ＢａＦＣｌｘＢｒ１－ｘ：Ｓｍ（０≤ｘ≤１）体系热释发光的研究，发现前人对ＢａＦＸ（Ｘ＝Ｃｌ，Ｂｒ）晶体热释发光的归属有误。结合多种技术的研究给出了正确的归属：ＢａＦＣｌｘＢｒ１－ｘ：Ｓｍ的第一、二、三个热释峰分别归属于Ｆ（Ｆ＾－），Ｆ（Ｃｌ＾－）和Ｆ（Ｂｒ＾－）心；ＢａＦＸ晶体的第一、二个热释峰分别归于Ｆ（Ｆ＾－）和Ｆ（Ｘ＾－）心。论证了结果的正确性，并分析了前人归属错误的可能原因。     

Synthesis and Characterization of Poly（butylene adipate-co-terephthalate） Catalyzed by Rare Earth Stearates

Rare earth （Nd, Y, La, Dy） stearates have been synthesized and used as single component catalysts for the polycondensation of dimethyl terephthalate, adipic acid and 1,4-butanediol for the first time preparing biodegradable poly（butylene adipate-co-terephthalate） （PBAT） with high molecular weight, The microstructures of PBAT were characterized by ^1H NMR spectra. The PBAT exhibits good mechanical properties such as high tensile strength （ca. 20 MPa） and long break elongation （〉700%）.     

Synthesis and Characterization of PE-g-MA/MgAl-LDH Exfoliation Nanocomposite via Solution Intercalation

Anorgano modifiedMgAl layereddoublehydroxide (OMgAl LDH )wassuccessfullyexfoliatedinthexylenesolutionofpolyethylene grafted maleicanhydride (PE g MA )underre fluxingcondition .APE g MA/MgAl LDHexfoliationnano compositewasformedaftertheprecipitationofPE g MAfromthedispersionsystem .ThestructureandthermalpropertyofthePE g MA/MgAl LDHexfoliationnanocompositewerechar acterizedbyX raydiffraction (XRD ) ,transmissionelectronmicroscopy (TEM ) ,andthermogravimetryanalysis (TGA ) .The…     

Synthesis and Catalytic Application of Homo-bimetallic Metallocene Complexes as Ethylene Polymerization Catalysts

ＩｎｔｒｏｄｕｃｔｉｏｎＩｔｉｓｗｅｌｌｋｎｏｗｎｔｈａｔｍｅｔａｌｌｏｃｅｎｅｓａｃｔｉｖａｔｅｄｗｉｔｈｍｅｔｈｙｌａｌｕｍｉｎｏｘａｎｅ (ＭＡＯ)ａｒｅｈｉｇｈｌｙａｃｔｉｖｅｈｏｍｏｇｅｎｅｏｕｓＺｉｅｇｌｅｒ Ｎａｔｔａｃａｔａｌｙｓｔｓｔｈａｔｐｒｏｄｕｃｅｐｏｌｙｏｌｅｆｉｎｗｉｔｈｃｏｎ ｔｒｏｌｌｅｄｓｔｅｒｅｏｒｅｇｕｌａｒｉｔｙａｎｄｎａｒｒｏｗｍｏｌｅｃｕｌａｒｗｅｉｇｈｔｄｉｓｔｒｉ ｂｕｔｉｏｎ ,1 4 ｈｏｗｅｖｅｒ,ｔｈｅｍｏｌｅｃｕｌａｒｗｅｉｇｈｔｏｆｔｈｅｐｏｌｙｍ…     

β-四(对羟甲基苯氧基)酞菁锌的合成及其抗肿瘤活性

以4-硝基邻苯二腈和对羟基苯甲醇为原料,经两步法设计并合成了两亲性β-四(对羟甲基苯氧基)酞菁锌(Ⅱ)光敏剂(1),其结构经UV-vis,1H NMR,IR,激光解吸电离飞行时间质谱(TOF-MS)及元素分析表征.用HE染料法和MTT染色法研究了1对Bel-7402人体肝癌细胞的抑制作用,考察了c(1)对Bel-7402细胞抑制率的影响.实验结果表明,当c(1)为50 mg·L-1时,抑制率达67%,其IC50=30.1 mg·L-1.     

使用四乙基氢氧化铵作为有机模板剂和常规硅铝源直接合成SSZ-13沸石分子筛

使用四乙基氢氧化铵作为有机模板剂,利用常规铝源和硅源而不需要高硅Y沸石作为起始原料,同时加入适量的沸石晶种直接合成了SSZ-13沸石分子筛.所合成的沸石产物结晶度好,具有良好的水热稳定性,并在氨选择性催化还原(NH₃-SCR)反应中显示出优异的催化性能,为其在工业上广泛应用提供了可能.     

托克维尔的自由概念

自由是19世纪法国政治思想家托克维尔政治哲学中最为核心的概念之一。托克维尔的自由概念既包含了古代自由、积极自由的成分,又包含了现代自由、消极自由的成分。在两种自由之间寻求某种平衡,构成了托克维尔自由观的核心内容。托克维尔的自由概念不仅彰显了托克维尔政治思想的复杂性、丰富性,也为重新思考关于自由的经典二分以及自由主义的自由观提供了重要的理论资源。