Theoretical and experimental study of photo-modulated reflectivity detections for transparent film/opaque substrate structures

A photo-modulated reflectivity method is used to evaluate thermal properties of bilayered structures composed of transparent films deposited on opaque substrates. In order to calculate the photo-modulated reflectivity variations of the bilayered structures induced by focused modulated laser irradiations, a 3-D theoretical model is presented. Due to the complexity of the 3-D theory, a finite element method is used to simulate the laser-induced temperature fields, thermoelastic displacement fields and dielectric constant variations, and finally the photo-modulated reflectivities. Then a quantitative investigation of the thermal properties of the transparent films deposited on opaque substrates can be performed by the experimental measurements and theoretical simulations. As examples, the thermal conductivities of ZnO and diamond films deposited on silicon substrates are evaluated and discussed. PACS 44.10.+i; 42.55.-f; 51.70.+f; 68.60.-p     

Mesoporous silica nanoreactors for highly efficient proteolysis

Protein digestion inside the nanoreactor channels of mesoporous silica (SBA-15) is reported, and evaluated by using peptide-mass mapping. Both proteases and substrates were efficiently captured within these biocompatible nanoreactors. After 10 minutes, the mass spectrum of the protein digests released from the mesoporous-silica-based nanoreactors revealed the presence of eight peptides covering 58% of the protein sequence with an intense signal (signal/noise ratio > 70). In comparison, the conventional overnight in-solution digestion of proteins under otherwise identical conditions generated only three peptides (27% sequence coverage). We propose that this order-of-magnitude increase in the proteolytic reaction rate is mainly attributed to two factors: substrate enrichment within mesoporous silica channels and enzyme immobilization. The surface properties and macrostructure of the mesoporous silica were studied to reveal their significant influence on proteolytic reactions.     

Theoretical simulation of a rotary motor driven by surface acoustic waves

A simulation model for theoretically studying the operation behavior of a rotary motor driven by surface acoustic waves (SAWs) is proposed. According to the model, some simulation results are obtained as follows: (1) as the rotor is excited by the SAWs, the motor experiences two phases, i.e., the acceleration phase and the steady phase; (2) the normal vibration amplitude A of SAWs has a very weak effect on the acceleration in the first phase but an enhancing effect on the steady velocity of the rotary motor; (3) as the number of the contact points between the rotor and the stator increases, the motor rotates more steadily; (4) as the rotor radius becomes smaller, both the acceleration and the steady angular velocity become greater. These features are in agreement with the experimental results.     

InGaAsP/InP双异质结发光管退化特性的研究

在室温(15～35℃),大气气氛中研究了InGaAsP/InP双异质结发光二极管的退化特性。有二种慢退化类型,连续工作104小时后,InGaAsP/InP发光二极管的电学参数、光学参数(除原有暗结构的B型慢退化器件,老化初期光功率下降10～20%外)均无明显变化。用红外电视选行扫描仪观察了老化过程中发光区的EL图象。研究了该器件的退化特性与EL图象的变化规律,找出了它们的对应关系。用扩展缺陷模型解释了InGaAsP/InP双异质结发光管的退化机理。     

北京地区哨声和甚低频发射的观测和研究

本文介绍了近几年在北京地区观测和研究哨声与甚低频发射的主要成果,几年来的季节性观测表明,除通常中低纬度观测到的哨声和甚低频发射类型外,还对某些类型提出了新的认识(如吱声、倒镰刀型分立发射、多描迹上升调等),在磁暴前1—3天曾观测到甚低频发射明显增加的现象,这为与地磁活动的相关研究提出了新的课题。最后,文中提出了联合应用哨声资料和同时的电离层垂直探测资料来计算,h_mF₂以上空间电子浓度垂直分布的一种方法,计算表明,在较低高度上,应用该法,可以取得较好的结果。     

小麦花粉植株花粉母细胞染色体的变异

本文对72个当代花粉植株(H_1)花粉母细胞的染色体变异情况进行了研究,并探讨了其染色体的稳定性问题.根据染色体倍性情况,72个小麦花粉植株可分为:3X,6X,8X.6X-2(缺体)和混倍体等五类. 在72个花粉植株中,87.5％为单倍体和二倍体.这和文献[1]的结果十分相近.同时观察到二倍体的染色体构型稳定,因此,花药培养方法可直接应用于育种工作. 在获得的近10％的异倍体和非整倍体植株中,缺体、八倍体以及混倍体等植株有的结了种子.文中还讨论了这些异倍体和非整倍体的产生和利用问题,认为花药培养方法可能获得染色体发生变异的新类型.     

重金属离子对猪胰α-淀粉酶活性影响的作用机理研究

通过在α-淀粉酶介质中加入Ce^3 ,Cd^2 和Pb^2 ,研究其对α-淀粉酶活性影响的作用机理。结果表明,低浓度重金属离子对酶活性有激活作用,高浓度则严重抑制酶活性。在高浓度下,Ce^3 ,Cd^2 和Pb^2 能完全竞争出α-淀粉酶中的Ca^2 。荧光滴定结果表明,Ce^3 ,Cd^2 和Pb^2 不仅可能完全占据Ca^2 的结合位点,而且还可能在Ca^2 的结合位点以外的氨基酸残基上结合,从而导致酶的构象改变。     

Photomechanical Switching Behavior of Semi‐Interpenetrating Polymer Network Consisting of Azobenzene‐Carrying Crosslinked Poly(vinyl ether) and Polycarbonate

Summary: A novel semi‐interpenetrating polymer network (semi‐IPN) with photomechanical switching ability was developed by a cationic copolymerization of azobenzene‐containing vinyl ethers in a matrix of a linear polycarbonate (PC). The semi‐IPN film showed reversible deformation upon switching the UV irradiation on and off and responded with unprecedented rapidity. The photomechanical effect is attributed to a reversible change between the highly aggregated and dissociated states of the azobenzene groups.

The reversible UV response of the length of the semi‐IPN film at 25 °C.     

多功能微波等离子体化学反应装置及其应用

建立了一台多功能微波等离子体化学反应实验装置,可用于化学合成、表面处理、多相催化等多种研究,为新方法、新工艺、新思路的实现提供了实验基础。     

线性啁啾光纤光栅色散补偿性能的数值分析

对线性啁啾光纤光栅的色散补偿性能进行了数值分析。结果表明 ,啁啾光栅时延曲线的纹波大小和线性度是影响其色散补偿性能的两个重要因素。对高斯型耦合系数分布光栅而言 ,更长的光栅将具有更佳的色散补偿性能