Hydrothermal synthesis and crystal structure of a layered inner-tunnel compound [(CuI)(2)(o-phen)(2)]

A layered inner-tunnel supramolecular compound 1, [(CuI)(2)(o-phen)(2)], was hydrothermally synthesized and structurally characterized by X-ray crystal diffraction. It crystallizes in triclinic system, space group P (1) over bar with a=0.7759(2) nm, b=0.9070(2) rim, c=0.91894(10) rim, alpha=96.306(14)degrees, beta=104.567(16)degrees, gamma=109.421(19)degrees, V=0.5768(2) nm(3), Z=1, R=0.0348, omegaR=0.0920.

Preparation of polymer/silica nanoscale hybrids through sol-gel method involving emulsion polymers (PMMA/SiO2)

The different poly (methyl methacrylate) (PMMA) /SiO2 hybrids were prepared through sol-gel method involving PMMA emulsion (emulsion method) and PMMA/THF solution (solution method). The samples were characterized by differential scanning calorimetry(DSC), thermogravimetry analysis(TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that PMMA/SiO2 composites in nanoscale were prepared by emulsion method, and its size of phase heterogeneity was less than that of solution method. Meanwhile, the polymer emulsion as the reactive medium was more suitable for the formation of SiO2 network.

利用聚合物乳液合成聚甲基丙烯酸甲酯/二氧化硅纳米杂化材料

通过正硅酸乙酯分别在聚甲基丙烯酸甲酯乳液和四氢呋喃溶液中的溶胶 -凝胶反应制备出不同的聚甲基丙烯酸甲酯 /二氧化硅复合材料 .利用扫描电镜、透射电镜、差热分析和热失重对试样进行了分析 .结果表明 ,利用聚合物乳液可以获得纳米分散的聚甲基丙烯酸甲酯 /二氧化硅复合材料 ,并且在某种程度上其分散尺度小于利用聚合物溶液获得的复合材料 .同时 ,利用聚合物乳液来制备聚甲基丙烯酸甲酯 /二氧化硅杂化材料更有利于凝胶过程中二氧化硅网络的形成

Investigation of Pr valence and relationship between bond covalency and T-c in Y1-xPrxBa2Cu3O7 (x = 0-1)

The valence of Pr and relationship between bond covalency and T-c in Y1-xPrxBa2Cu3O7 (x = 0-1) have been studied using complex chemical bond theory. The results indicate that the depression of superconductivity in Y1-xPrxBa2Cu3O7 can be reasonably explained by bond covalency difference for the bonds between CuO2 plane and CuO chain. T-c decreases with the decreasing of bond covalency difference and reaches zero when bond covalency difference is zero (or bond covalency in CuO2 exceeds that in CuO chain) at Pr concentration 0.55 and valence +3.30. These are in good agreement with the experiments and meanwhile suggest that the valence of Pr is + 3.30 in Y1-xPrxBa2Cu3O7. The results also indicate that for Pr valence less than +3.15, superconductivity always exists for whatever Pr concentration, whereas for Pr with a valence of +4.0, superconductivity disappears as soon as Pr concentration exceeds 0.19. This supports with the viewpoint that higher valence Pr will contribute more electrons to CuO2 plane, filling the mobile holes responsible for conduction. For PrBa2Cu3O7 with no Ba-site Pr, our calculation suggests that it will be a superconductor if the average valence of Pr is less than +3.15. (C) 1998 Published by Elsevier Science B.V. All rights reserved.

The crystal structure and drawing-induced polymorphism in poly(aryl ether ketone)s .1. Poly(oxybiphenyl-4-4'-diyloxy-1,4-phenylenecarbonyl-1,3-phenylenecarbonyl-1,4-phenylene)

Crystal structure and polymorphism induced by uniaxial drawing of a poly(aryl ether ketone) [PEDEKmK] prepared from 1,3-bis(4-fluorobenzoyl)benzene and biphenyl-4,4'-diol have been investigated by means of transmission electron microscopy (TEM), electron diffraction (ED), wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC) techniques. The melting and recrystallization process in the temperature range of 250-260 degrees C, far below the next melting temperature (306 degrees C), was identified and found to be responsible for the remarkable changes in lamellar morphology. Based on WAXD and ED patterns, it was found that crystal structure of isotropic-crystalline PEDEKmK obtained under different crystallization conditions (melt-crystallization, cold-crystallization, solvent-induced crystallization, melting-recrystallization, and crystallization from solution) keeps the same mode of packing, i.e., a two-chain orthorhombic unit cell with the dimensions a = 0.784 nm, b = 0.600 nm, and c = 4.745 nm (form I). A second crystal modification (form II) can be induced by uniaxial drawing above the glass transition temperature, and always coexists with form I. This form also possesses an orthorhombic unit cell but with different dimensions, i.e., a = 0.470 nm, b = 1.054 nm, c = 5.064 nm. The 0.32 nm longer c-axis of form II as compared with form I is attributed to an overextended chain conformation due to the expansion of ether and ketone bridge bond angles during uniaxial drawing. The temperature dependence of WAXD patterns for the drawn PEDEKmK suggests that form II can be transformed into the more stable form I by relaxation of overextended chains and relief of internal stress at elevated temperature in absence of external tension.

STRUCTURE-ANALYSIS OF MOLTEN CACL2-KCL SYSTEM BY X-RAY-DIFFRACTION

Radial distribution function of CaCl2-KCl (1:2 mol) melt was measured by X-ray scattering of high temperature liquid. The nearest neighbour distances of Ca2+-Cl-, K+-Cl- and Cl--Cl- ionic pairs are 0.278, 0.306 and 0.380 nm, respectively, Discussion on the relation between structure and physicochemical properties in the melt was simply done in this paper.

CF_4等离子体表面氟化PTMSP膜

本文对聚三甲基硅基丙炔(PTMSP)膜进行CF_4等离子体表面氟化研究。改性的PTMSP膜氧氮选择性显著提高(P_(O_2)/P_(N_2)=4-5,P_(O_2)=10~2-10~3barrer)。等离子体改性条件,如处理时间、单体压力、放电功率对PTMSP膜透气性的影响进行了研究。XPS谱分析表明改性后,膜表层化学组成发生了显著变化、碳硅含量大幅度减小,氟含量随着处理程度的增加而增加,氟碳比与膜的选择性有着密切的关系,当 F/C>1时,膜的P_(O_2)/P_(N_2)可达4以上。

CaCl_2-KCl熔体结构的X射线衍射分析

用高温液态X射线衍射方法,测定了摩尔比为1∶2的CaCl_2-KCl熔体的径向分布函数。结果表明,熔体中Ca~(2+)-Cl~-、K~+-Cl~-和Cl~--Cl~-离子对间的最近邻距离分别为0.278,0.306和0.380nm.由于Ca~(2+)与Cl-间的强Coulomb作用,在熔融的摩尔比为1∶2的CaCl_2-KGl体系中,Cl~--Cl~-间的最近邻距离明显小于纯KCl熔体中Cl~--Cl~-间的最近邻距离。

涂渍FFAP、PEG-20M、XE-60硅膜改性弹性玻璃毛细管柱的研制

硅膜改性弹性玻璃毛细管柱做为一种新柱型,它具有类似弹性石英柱的柔性和惰性,也具有玻璃柱制作容易、材质易得的优点。硅膜做为固定相载体的色谱特性研究目前报道还很少,非极性硅酮相在其上的交联我们曾做过报

国外CdTe(CuInSe_2)/CdS太阳电池的进展和我国的现状

本文综述了CdTe/CdS和CuInSe_2/CdS薄膜太阳电池的进展,讨论了这两种电池的发展前景。

助熔剂法生长YVO_4:RE~(3+)晶体

稀土钒酸盐是很好的发光和激光材料。本文探讨了助熔剂法生长YVO_4:RE~(3+)(RE~(3+)=Pr~(3+),Sm~(3+),Tb~(3+))晶体的工艺条件。讨论了V_2O_5与Pb_2P_2O_7为助熔剂和温度对晶体成核,生长习性和缺陷的影响。并测定了晶体的结构参数。分别以V_2O_5和Pb_2P_2O_7为助熔剂进行YVO_4:RE~(3+)晶体的生长,结果表明用V_2O_5为助熔剂比用Pb_2P_2O_7为助熔剂要优越得多。以

Ce:BaAlF_5晶体生长及其光谱特性

采用坩埚下降法生长了 Ce:BaAlF_5单晶、X 射线衍射表明其结构为α-BaAlF_5构型,属于正交晶系,晶胞参数为α=5.146(?),b=7.191(?),c=19.647(?)。测定了晶体的反射光谱、吸收光漕、激发光谱和荧光光谱。Ce~(3+)离子在290nm 附近有一个强吸收峰,为4f-5d 能级的跃迁。在292nm 激发下,有306.5nm 和324nm 两个发射峰、即Ce~(3+)的~2D 能级到~2F_5/2和~2F_7/2能级的跃迁发射。晶体在紫外光照射下发紫光和兰白光。在254nm 激发下,除了 Ce_~(3+)的发射峰,还存在351nm和494nm 两个发光峰,前者与 Ce~(3+)的324nm 发射峰部分重叠,后者为对称性较好的宽带峰。这两个发光峰被认为是晶体缺陷产生的色心发光。

Amorphane sesquiterpenes from a marine Streptomyces sp.

The chemical investigation of the crude extract of the marine-derived Streptomyces sp. M491 yielded three new sesquiterpenes, namely, 10 alpha,11-dihydroxyamorph-4-ene (4), 10 alpha,15-dihydroxyamorph-4-en-3-one (6), and 5 alpha,10 alpha,11-trihydroxyamorphan-3-one (7). In addition, the known compounds 10 alpha-hydroxyamorph-4-en-3-one (2), o-hydroxyacetanilide, genistein, prunetin, and indole-3-carbaldehyde and the macrolide antibiotic chalcomycin A were identified. The structures were determined on the basis of spectroscopic analysis, especially 1D and 2D NMR data. This is the first report of these sesquiterpenes from bacteria.