二甲基硫醚与过氧化氢反应机理的研究及溶剂效应

采用密度泛函理论的B3LYP方法,在6-311+G(d,p)基组水平上研究了CH3SCH3与H2O2的微观反应机理,全参数优化了反应势能面上各驻点的几何构型,振动分析和内禀反应坐标(IRC)分析结果证实了中间体和过渡态的真实性,计算所得的键鞍点电荷密度的变化情况也确认了反应过程.结果表明,反应共分2步进行,主要经历了O对S的进攻、H转移以及O-O键断裂的历程.并分别考察了其在水中和甲苯的溶剂效应.结果表明,溶剂效应降低了反应的活化能,并使过渡态红外光谱蓝移.     

Surface-initiated nitroxide-mediated radical polymerization of 2-(dimethylamino)ethyl acrylate on polymeric microspheres

2-(Dimethylamino)ethyl acrylate (DMAEA) was grafted from the surface of alkoxyamine-functionalized crosslinked poly(styrene-co-chloromethylstyrene) microspheres by nitroxide-mediated radical polymerization (NMRP). Latex particles (∼60 nm diameter) bearing chloromethyl groups were synthesized by emulsion polymerization. N-tert-butyl-N-(1-diethyl phosphono-2,2-dimethylpropyl)nitroxide (SG1) was then immobilized on the particle surface. Microspheres grafted with the homopolymer pDMAEA, as well as block copolymers poly(styrene-b-DMAEA) and poly(butyl acrylate-b-DMAEA) were prepared by surface-initiated NMRP in N,N-dimethylformamide at 112 °C, with the addition of free SG1 to ensure that control is maintained. Particle size increases with number average molecular weight (M_n) of untethered polymers. The polymerizations exhibit linear first order kinetic plots and slight curvature of evolution of M_n with conversion. The functional microspheres were analyzed by infrared spectroscopy, transmission electron microscopy and thermal analysis, as well as their dispersibility in water; the results support the formation of surface-grafted pDMAEA on the microspheres.     

Microstructure and mechanical behavior of AlSiCuMgNi piston alloys reinforced with TiB2 particles

AlSiCuMgNi piston composites reinforced with in-situ TiB₂ particles were fabricated by mixing salts reaction process successfully. Microstructures of the composites were observed by mean of scanning electron microscope (SEM) and transmission electron microscope (TEM). X-ray diffraction (XRD) was used to identify the phases in the composites. TiB₂ reinforcement grows in equiaxed or near equiaxed shape and the interfaces between reinforcements and matrix are clear. Compared with the matrix alloys, the composites show an obvious aging peak and an incubation time in the hardness. The aging is accelerated in the composites reinforced with TiB₂. At room temperature, the ultimate tensile strength (UTS) of the composites increases as the percentage of TiB₂ reinforcement increases. When the temperature is beyond 250°C, the ultimate tensile strength of the piston composites decreases sharply. The fracture surfaces of the piston composites are analyzed.     

Comparison of structural and photoluminescence properties of ZnO thin films grown by pulsed laser deposition and ultrasonic spray pyrolysis

ZnO thin films have been deposited by pulsed laser deposition (PLD) and ultrasonic spray pyrolysis (USP) method, respectively. X-ray diffraction and transmission electron microscopy characterizations indicate that ZnO film grown by PLD exhibits better crystallinity than that grown by USP. Photoluminescence spectra show that the near-band edge ultraviolet emission of film grown by PLD is narrower and shifts to higher energy, compared with that of film grown by USP. In the visible range, ZnO film grown by PLD exhibits four local level emission centered at 470 nm, 486 nm, 544 nm, and 613 nm, respectively, while the film grown by USP only presents a weak broad band emission centered at 502 nm. Hall measurement shows higher carrier density and lower hall mobility in ZnO film grown by PLD than that in film grown by USP. The higher density of intrinsic defects as well as higher crystallintiy is considered to account for the difference of photoluminescence in ZnO film grown by PLD with that in film grown by USP.     

基于新息相关性自调整的交互多模型算法

本文通过引入新息相关法,提出了一种基于新息相关性自调整的交互多模型算法。该方法首先利用模型概率识别出最可能近似真实模式的模型,而后针对该模型应用新息相关法滤波,在系统的数学模型和噪声的统计模型不精确的情况下,通过监测残差是否为白噪声,来相应地调整卡尔曼增益,从而使卡尔曼滤波达到最佳。     

基于神经网络的GIS空间数学模型研究

文中对空间数学模型的建立方法以及不同方法的优缺点进行了分析比较,指出基于人工神经网络的建模方法是目前GIS应用领域中行之有效的方法之一,最后通过实例对该方法的有效性进行了验证。     

ICP-AES测定低合金钢中钨的含量

研究了用ICP-AES法测定低合金钢中元素钨的测定方法。选用波长239.709nm谱线,考虑共存元素之间的干扰问题,控制适当酸度,用ICP-AES法测定低合金钢中元素钨,相对标准偏差小于4%,加标回收率在95.5%～104.0%之间,分析方法快速、简便,分析结果准确。     

立式行星磨磨腔内流场的三维数值模拟

针对立式行星磨磨腔内流场的特点,运用计算流体力学方法对磨腔内流场进行三维分析。根据模拟结果,首次提出磨腔内流场结构特点,得到流场的速度场和压力场,为进一步分析被磨物料在磨腔内的运动和磨辊密封结构的设计提供理论基础。     

Bonding strength of graded anti-corrosive coatings of fluoroethylenepropylene （FEP）/polyphenylene sulfide （PPS）

Fluororesin-based anti-corrosive coatings including graded FEP/PPS were prepared on carbon steel by melt powder coating, the bonding strength of all coating systems was determined by the pull-off test. It is found that the poor adhesion of fluororesin coatings to metallic substrates is improved obviously by the graded coating structure of FEP/PPS, and the bonding strength reaches up to 11.8 MPa for the five-layer system. Examination by electron probe microanalysis （EPMA） verifies that the distribution of main components is graded in the five-layer system, which is responsible for the enhancement of the interfacial bonding.     

黄金矿山竖井设计的新技术

介绍了黄金矿山竖井设计新技术的应用情况，多绳摩擦轮提升机提升、复合罐道和冷弯方钢管罐道、玻璃钢安全隔网、简易锚杆安装罐道梁等新技术值得在竖井建设、竖井改造工程中参考应用。