Mechanism of Enhanced Dielectric Properties of SiC/Ni Nanocomposites

Dielectric properties of SiC/Ni nanocomposites prepared by a simple and facile electroless plating approach at X band are investigated. Compared to the original SiC nanopartieles （SiCp）, the real part of the permittivity, ε＇, and the dielectric loss tangent tang δe of SiC/Ni nanocomposites are clearly enhanced by about 31% and 33%, respectively. The effective equations for complex permittivity of SiC/Ni nanoeomposites are proposed. We also calculate ε＇ and tan δe of SiC/Ni nanoeomposites and the calculated results are well consistent with the measured data.     

Experimental Study on Liquid Free Surface in Buoyant-Thermocapillary Convection

We investigate the surface deformations of buoyant-thermocapillary convection in a rectangular cavity due to gravity and temperature gradient between the two sidewalls. The cavity is 52mm×42 mm in horizontal cross section, the thickness of liquid layer h is changed from 2.5 mm to 6.5 mm. Surface deformations of h = 3.5 mm and 6.0mm are discussed and compared. Temperature difference is increased gradually, and the flow in the liquid layer will change from stable convection to unstable convection. Two kinds of optical diagnostic system with image processor are developed for study of the kinetics of buoyant-thermocapillary convection, they give out the information of liquid free surface. The quantitative results are calculated by Fourier transform and correlation analysis, respectively. With the increasing temperature gradient, surface deformations calculated are more declining. It is interesting phenomenon that the inclining directions of the convections in thin and thick liquid layers are different. For a thin layer, the convection is mainly controlled by thermocapillary effect. However, for a thick layer, the convection is mainly controlled by buoyancy effect. The surface deformation theoretically analysed is consistent with our experimental results. The present experiment proves that surface deformation is related to temperature gradient and thickness of the liquid layer. In other words, surface deformation lies on capillary convection and buoyancy convection.     

Experimental Investigation of Influence of Interfacial Tension on Convection of Two-Layer Immiscible Liquid

Bdnard-Marangoni convections of two-layer fluids heated from the bottom are investigated experimentally with a particle imagine velocimetry. The flows are visualized from the side, and various velocity fields near the onset of convection, such as three-layer vortex convective patterns, are observed when the depth ratio varies in a wide range. A new classification of the convective patterns is proposed with more detail than in previous studies. The analysis of the results indicates that the interface tension greatly influences the motion intensities of the bottom and top layers. The dimensionless wave number increases with the Bond number when the motion in the top layer is not more intense than that in the bottom layer, which agrees with the theoretical prediction.     

清洗方法对KDP晶体抛光表面质量的影响

为了提高KDP晶体的表面质量,减少清洗时新损伤的引入,降低清洗过程对抛光后晶体表面质量的影响,本文采用超声波、酒精棉、擦镜纸以及酒精棉与擦镜纸相结合的方法,对抛光后的KDP晶体表面进行了清洗.利用光学显微镜对不同清洗方法得到的表面质量进行检测对比.结果表明,酒精棉与擦镜纸相结合进行清洗为较理想的清洗方法,可以有效防止清洗中存在的表面潮解及新划痕的引入,清洗后的抛光表面粗糙度Ra为2.152 nm.     

黄腐酸金属络合物的X射线光电子能谱研究

腐植酸(包括黑腐酸HA和黄腐酸FA)广泛存在于自然界^[1-4].各种不同来源的腐植酸在结构上基本相似,反映在它们的物化性质与生物活性方面也大致相同.一般认为这种结构尚不太清楚的大分子有机化合物往往同各种金属离子结合起螯合剂的功效.对金属在环境中的积聚、迁移和固定起着十分重要的作用^[5-7].近年来利用各种现代的方法与仪器来研究腐植酸与金属离子的作用机理及其反应物结构的报道很多,但研究结果很不一致,结论也不统一^[8-13].     

MnO2/CNTs/PTFE三元复合材料的水热原位合成及超级电容性能研究

采用水热原位合成技术制备了MnO2、MnO2/CNTs及MnO2/CNTs纳米复合材料,研究了MnO2/CNTs/PTFE三元复合材料在化学电源领域的应用.用X射线衍射分析材料结构、扫描电镜与透射电镜观察材料形貌,用恒流充放电、循环伏安、交流阻抗谱研究其用作超级电容器和锂离子电池负极材料的电化学性能.结果表明,导电载体...     

生物医用高分子微球研究进展

综述了生物医用高分子微球载体的制备方法、表面功能化途径以及生物活性物质的固定化方法,并对高分子微球在生物医学领域的应用作了简要介绍。     

二甲氧基羟基苯基荧光酮光度法测药物中的钼

钼是维持人体健康的重要微量元素之一,主要作用是防止龋齿,促进铁的新陈代谢,保持男子的性能力,预防贫血,尤其具有抗癌防癌等生物学效应。钼缺乏与很多疾病有关,尤其是动脉粥样硬化的致病因素。为了保持人体健康,就要保证微量元素钼的正常摄入量。世界卫生组织估     

考虑水资源税下的电厂与电网之间双重边际效应模型

以电厂和电网分开政策下引发的双重边际效应为背景,建立了考虑水资源税的序贯博弈模型。在"厂网分开"背景下,探讨了水资源税对博弈参与方(电厂、电网)最优决策、供应链效率的影响。考察了影响上网电价及供应链效率的主要因素。结论显示,水资源税的下调会负向影响电厂最优电价,进而促进电厂售电量、提升其净利润,最终削弱双重边际效应,改善了供应链效率。此外,本文运用数值算例验证了主要研究发现。     

新型红外非线性光学晶体BaGa2GeSe6的生长与器件制备

钡镓锗硒(BaGa₂GeSe₆,BGGSe)晶体是由中国科学家发明的一种性能优异的新型红外非线性光学材料.目前国内未见到关于该晶体的大尺寸制备报道.本研究采用自制的双温区管式炉成功合成出BGGSe多晶,单次合成量达到400 g;采用坩埚下降法生长出大尺寸高质量BGGSe单晶,尺寸为φ30 mm×90 mm,为国内首次;通过定向、切割和抛光等处理工艺,成功制备出BGGSe晶体器件,为该晶体下一步的应用研究打下了坚实基础.