Design and Fabrication of Al_2O_3/SiO_2 Double-Layer Antireflection Coatings on 4H-SiC Substrate

在4H-SiC基底上设计并制备了Al2O3/SiO2紫外双层减反射膜,通过扫描电镜(SEM)和实测反射率谱来验证理论设计的正确性。利用编程计算得到Al2O3和SiO2的最优物理膜厚分别为42.0nm和96.1nm以及参考波长λ=280nm处最小反射率为0.09%。由误差分析可知,实际镀膜时保持双层膜厚度之和与理论值一致有利于降低膜系反射率。实验中应当准确控制SiO2折射率并使Al2O3折射率接近1.715。用电子束蒸发法在4H-SiC基底上淀积Al2O3/SiO2双层膜,厚度分别为42nm和96nm。SEM截面图表明淀积的薄膜和基底间具有较强的附着力。实测反射率极小值为0.33%,对应λ=276nm,与理论结果吻合较好。与传统SiO2单层膜相比,Al2O3/SiO2双层膜具有反射率小,波长选择性好等优点,从而论证了其在4H-SiC基紫外光电器件减反射膜上具有较好的应用前景。Al2O3/SiO2 double-layer UV antireflection coatings were designed and fabricated on 4H-SiC substrate,and the validity of theoretical design was further verified by scanning electron microscope (SEM) and reflection spectrum. The optimal physical thickness of Al2O3 and SiO2 is 42.0 nm and 96.1 nm respectively by programming calculation. And then the minimum reflectance of 0.09% is obtained at reference wavelength λ=280 nm. According to error analysis,keeping the sum of double-layer thickness consistent with theoretical value is helpful to reduce the reflectance. In addition,the refractive index of SiO2 should more accurate and the refractive index of Al2O3 should be controlled close to 1.715 in the experiment. Al2O3/SiO2 double-layer coatings were deposited on 4H-SiC substrate by electron beam evaporation and the physical thickness is 42 nm and 96 nm respectively. SEM images show that the deposited layers and the substrate perform good adhesion to each other. The practical minimum reflectance is 0.33% at λ=276 nm which is close to theoretical value. Compared with conventional SiO2 single layer,Al2O3/SiO2 double-layer coatings show low reflectance and better wavelength selectivity. These results make the possibility for 4H-SiC based UV optoelectronic devices with Al2O3/SiO2 films as antireflection coatings

中国波斑鸨保护生物学系统研究

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中国鸨类的分布与现状

依据1990-2002年调查资料,分析了我国国家一级保护动物3种鸨类的分布和现状。大鸨(Otis tarda):东方亚种(O.t.dybowskii)中国种群繁殖于黑龙江西南部、吉林西部、内蒙古东部和中部、宁夏北部和甘肃,少数个体滞留在南部繁殖地越冬。指名亚种(O.t.tarda):中国种群繁殖于新疆北部和西部。越冬区尚不清楚,推测可能在南亚一带,新近在新疆察布查尔发现越冬个体。繁殖地生境为草原、荒漠草原和农田;越冬地生境为挥湖沿岸滩涂、草甸、草甸草原和麦地等。波斑鸨(Chlamydotis undulata macqueeni):中国种群繁殖于准噶尔盆地周边、乌伦古河两岸、巴里坤及吐鲁番盆地南部、内蒙古西部和甘肃西部。准噶尔盆地东部木垒东北为国际间的主要繁殖区之一。生境为荒漠和荒漠草原,越冬地在西亚和南亚一带。小鸨(Tetrax tetrax):中国种群繁殖于新疆北部,我国为繁殖区的东界。生境为草原和半荒漠,越冬于南亚一带。我国种群数量十分稀少

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3D打印（亦称增材制造）技术因其独特的材料成型优势，在组织工程、航空航天、汽车制造、以及电子工业等众多领域显示出巨大的应用潜力。然而，在实际生物医学应用中，3D打印生物器件和组织器官除了要求具有复杂的结构和优异的生物学性能外，其打印结构的表面性质也需满足某些特定的要求，如3D打印组织骨架和器官必须具有生物相容性、抗菌性及细胞粘附性等。因此，将3D打印与传统表面修饰技术相结合，在不改变材料三维结构的基础上调控其表面生物化学性质，从而赋予3D打印生物骨架器官多功能化，可实现更为广泛的应用。本文以3D打印生物骨架及器官的表面修饰为主要内容对就近年来3D打印生物医用材料的最新研究进展进行了综述

Surface Enhanced Raman Spectroscopic Studies of Pyridine Adsorbed on Ti/Au@SiO2 Film Electrode

基于壳层隔绝纳米粒子增强拉曼光谱技术，合成了Au@SiO2纳米粒子，并对其进行了相关表征. 结果表明，包裹的二氧化硅层连续、致密，Au@SiO2膜/Ti电极上可获得金属钛电极上吸附吡啶分子的高质量表面增强拉曼光谱（SERS）信号. 通过Pt、Ni电极的测试，证实该信号源于吸附在基底表面的吡啶分子. 此外，Au@SiO2膜/Ti电极上吸附吡啶分子的现场SERS光谱研究表明，在-0.1 V ~ -0.6 V电位区间，吡啶分子平躺吸附，从-0.6 V起吸附的吡啶分子由平躺逐转变为垂直，而当电位为-1.2 V时，电极表面析氢，吡啶脱附.This study was performed based on shell-isolated nanoparticles-enhanced Raman spectroscopy (SHINERS) technology. The Au@SiO2 nanoparticles were prepared and characterized by TEM and cyclic voltammetry. It was shown that the shell of SiO2 was compact. The high quality signal measured by surface enhanced Raman spectroscopy (SERS) was obtained from the adsorbed pyridine on Ti/Au@SiO2 electrode. The origin of the SERS signals was further confirmed by testing Pt and Ni electrodes. In addition, potential dependent adsorption behavior was investigated. It was found that pyridine was adsorbed parallel on the surface from -0.1 V to -0.6 V, and converted to perpendicular adsorption from -0.6 V. At last, pyridine was desorbed from the electrode accompanied with hydrogen evolution when the potential moved to -1.2 V.国家自然科学基金项目（No. 21073128，No. 21033007，No. 20973120）和江苏省自然科学基金项目（No. BK2012187）资助作者联系地址：College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, Jiangsu, ChinaAuthor's Address: 苏州大学材料与化学化工学部，江苏 苏州 215123通讯作者E-mail：[email protected]