Synthesis and properties of polymer from bis‐3,4‐ethylenedioxythiophene substituted acenaphthenequinoxaline

A new electrochoromic polymer poly(8,11‐bis(3,4‐ethylenedioxy thiophen‐2‐yl)acenaphtho[1,2‐b]‐quinoxaline) (PBEAQ) was synthesized by electrochemical polymerization of the corresponding monomer (BEAQ) in a 0.1 M tetraethylammonium tetrafluoroborate (TEABF₄) dichloromethane–acetonitrile (2 : 1, v : v) solution. The monomer and polymer were characterized by elemental analysis, ¹H‐NMR, IR, and UV‐vis spectroscopy. The electrochemical and optical properties of polymer were investigated by cyclic voltammetry and UV‐vis spectroscopy. Cyclic voltammetry and spectroelectrochemistry studies demonstrated that the polymer can be reversibly reduced and oxidized (both n‐ and p‐doped) between ?2 V and +1.5 V vs. Ag/Ag⁺. The polymer had a transmissive light blue color in the oxidized state and reddish color in the reduced state. Undoped polymer shows UV‐vis absorption peaks at 615 nm in solution, 650 nm in solid state, and has an optical band gap of 1.5 eV. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

New soluble rigid rod copolymers comprising alternating 2-amino-pyrimidine and phenylene repeat units: Syntheses, characterization, optical and electrochemical properties

A new type - π-conjugated copolymers of 2-amino-pyrimidine was prepared between 2-amino-4,6-diiodidepyrimidine and 1,4-dibromo-2,5-dialkoxybenzene by Sonogashira polycondensation. The structures of the copolymers were elucidated by FT-IR, ¹H NMR and ¹³C NMR, fluorescence spectroscopy, gel permeation chromatography, thermal analysis and element analysis. The derived polymers were soluble in common organic solvents and trifloroacetic acid and exhibited good thermal stability. They emitted green light under UV irradiation in solid state and blue or green light in solution phase, respectively. Electrochemical behavior of these new polymers depicted facile p-doping and good electron-transporting properties. These polymers displayed bathochromic shift when protonated with CH₃SO₃H acid in chloroform solutions or m-cresol solutions and the red-shifted peaks were observed from 490 nm to 652 nm. XRD patterns of copolymers showed that the intensity of peaks was enhanced with increasing alkyloxy chain length.     

新疆入境旅游客源市场分析及开发策略

本文分析了新疆入境旅游客源市场的时间结构和区域结构(分析了独联体客源市场与游客地理集中指数的关系)及游客平均停留天数和消费结构,揭示了新疆入境旅游客源市场的现状,并提出了开拓新疆国际旅游客源市场的对策和措施。     

氮氧化物光波导传感元件的研究

氮氧化物是造成全球变暖和产生酸雨的主要物质,因此氮氧化物气体的检测在环境监测和化学工业等许多领域中具有重要意义.该文以甲基绿为敏感试剂,将其掺杂于聚乙烯醇溶液后固定在钾离子玻璃光波导上,研制出检测氮氧化物气体的高灵敏度光波导传感元件.该元件具有响应快、成本低、易制作等特点.可检测出浓度为1.91 mg/m3的二氧化氮气体.     

用三维电镜断裂面图像数据测试空穴形状

对金属基复合材料的断裂面,进行三维损伤测试,改进Gurson,Tveergard提出的损伤模型。为建立有限单元模型,进行数值模拟计算,分析在不同三维应力下空穴聚合时空穴几何形状的变化。为准确模拟金属材料及其零部件在多向外载荷下的损伤过程,判断损伤机理提供合理强度评价方法和科学依据.     

漏极散射机制对弹道和非弹道沟道应变硅二极管中电子输运特性的影响

在漏极区域，多重散射对于沟道区域有无散射的应变硅二极管中电子传输性能的影响进行了数值研究。使用应变和散射模型，对于非弹道（有散射）沟道硅二极管的性能与弹道（无散射）沟道的硅二极管的性能进行了比较研究。研究结果表明应变模型中的电子速度和电流的值比无应变模型的相应值更高，弹道沟道模型中的电子速度和电流的值比非弹道沟道模型中的相应值更高。使用应变和散射模型，漏极区域中的每个散射机制对于硅二极管性能的影响进行了分析。对于弹道沟道模型，结果表明谷间光学声子散射会提高器件的性能，而谷内声学声子散射会降低器件的性能。对于应变模型，结果表明较大应变硅能带分裂可以抑制谷间声子散射率。总而言之，为了提高纳米级弹道器件性能，对于漏极区域应变和散射机制模型的研究是很有必要的。     

榅桲果实中生物碱粗提物的抑菌作用研究

经过定性实验确定榅桲中含生物碱,用分光光度法测定榅桲果实总生物碱含量为1.2%。又对榅桲果实生物碱粗提物对几种常见菌株进行体外抑菌实验。结果表明,榅桲果实生物碱粗提物对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌有一定的抑制作用,但对黑曲霉、根霉、青霉和酵母菌的抑制效果不太明显。     

Photocurrent analysis of AgIn<Subscript>5</Subscript>S<Subscript>8</Subscript> crystal

The photocurrent (PC) spectrum of AgIn₅S₈ crystal consists of a single peak, which provides to determine the bandgap energy by applying the Moss rule. The temperature dependence of the bandgap energy was also calculated. The PC dramatically increased by pre-illumination with light having wavelength corresponding to the bandgap of AgIn₅S₈. The temperature-dependent PC of the sample was measured at different temperatures from 80 to 300 K and the PC spectrum consisted a single broad peak. Thermal quenching of the PC was observed to start at ～105 K and the PC completely quenched at ～180 K. The quenching mechanism was discussed in terms of the two-centre model. The height of the PC peak rised linearly with applied voltage up to 5.0 V under constant intensity of light. Similarly, the dark current–voltage characteristics consisted of a single region dominating an ohmic behaviour, and no space charge limited region was apparent at various temperatures up to 20 V.     

复杂空间桁架结构在不同约束条件下的有限元模拟

主要介绍了应用MATLAB计算复杂空间桁架结构在不同条件下节点位移、节点外力、单元应变及应力.此外还应用MATLAB建立了GUI界面以获得更好的通用性,并举例进行了说明.     

Computer simulation of the damage evolution of fiber‐reinforced polypropylene‐matrix composites with matrix defects

The damage evolution of fiber‐reinforced polypropylene‐matrix composites with matrix defects was studied via a Monte Carlo technique combined with a finite element method. A finite element model was constructed to predict the effects of various matrix defect shapes on the stress distributions. The results indicated that a small matrix defect had almost no effect on fiber stress distributions other than interfacial shear stress distributions. Then, a finite element model with a statistical distribution of the fiber strength was constructed to investigate the influences of the spatial distribution and the volume fraction of matrix defects on composite failure. The results showed that it was accurate to use the shear‐lag models and Green's function methods to predict the tensile strength of composites even though the axial stresses in the matrix were neglected. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 64–71, 2007