A Breakdown Criterion of Free Molecular Flows and an Optimum Analysis of EBPVD

Two important issues in electron beam physical vapor deposition (EBPVD) are addressed. The first issue is a validity condition of the classical cosine law widely used in the engineering context. This requires a breakdown criterion of the free molecular assumption on which the cosine law is established. Using the analytical solution of free molecular effusion flow, the number of collisions (N-c) for a particle moving from an evaporative source to a substrate is estimated that is proven inversely proportional to the local Knudsen number at the evaporation surface. N-c = 1 is adopted as a breakdown criterion of the free molecular assumption, and it is verified by experimental data and DSMC results. The second issue is how to realize the uniform distributions of thickness and component over a large-area thin film. Our analysis shows that at relatively low evaporation rates the goal is easy achieved through arranging the evaporative source positions properly and rotating the substrate.

Preparation and optical properties of CdTe/CdO center dot nH(2)O core/shell nano-composites in aqueous solution

The deposition of CdO center dot nH(2)O On CdTe nanoparticles was studied in an aqueous phase. The CdTe nanocrystals (NCs) were prepared in aqueous solution through the reaction between Cd2+ and NaHTe in the presence of thioglycolic acid as a stabilizer. The molar ratio of the Cd2+ to Te2- in the precursory solution played an important role in the photoluminescence of the ultimate CdTe NCs. The strongest photoluminescence was obtained under 4.0 of [Cd2+]/[Te2-] at pH similar to 8.2. With the optimum dosage of Cd(II) hydrous oxide deposited on the CdTe NCs, the photoluminescence was enhanced greatly. The photoluminescence of these nanocomposites was kept constant in the pH range of 8.0-10.0, but dramatically decreased with an obvious blue-shifted peak while the pH was below 8.0. In addition, the photochemical oxidation of CdTe NCs with cadmium hydrous oxide deposition was markedly inhibited.

Optimum hot electron production with low-density foams for laser fusion by fast ignition

We propose a foam cone-in-shell target design aiming at optimum hot electron production for the fast ignition. A thin low-density foam is proposed to cover the inner tip of a gold cone inserted in a fuel shell. An intense laser is then focused on the foam to generate hot electrons for the fast ignition. Element experiments demonstrate increased laser energy coupling efficiency into hot electrons without increasing the electron temperature and beam divergence with foam coated targets in comparison with solid targets. This may enhance the laser energy deposition in the compressed fuel plasma.

Double refraction and reflection of sequential crystal interfaces with arbitrary orientation of the optic axis and application to optimum design

The general formulation of double refraction or internal double reflection for any directions of incidence and arbitrary orientation of the optic axis in a uniaxial crystal is analysed in terms of Huygens' principle. Then double refraction and double reflection along the sequential interfaces in a crystal are discussed. On this basis, if the parameters of the interface are chosen appropriately, the range of angular separation between the ordinary ray and extraordinary ray can be much greater, It is useful for crystal element design. Finally, as an example, an optimum design of the Output end interface for a 2 x 2 electro-optic switch is given.

蓝藻应答高 pH 胁迫的亚细胞蛋白质组学研究

蓝藻是迄今地球上发现的最古老、分布最广和最具多样性的光合自养原核生物，其细胞结构简单，具有类似于植物的光合作用，是研究光合作用及其它代谢过程重要的模式生物。由于这类生物起源于远古前寒武纪，但至今依然繁多，在极端寒冷的南北极冰湖和近于沸腾温度的温泉，以及高盐、强碱的极端环境中均有存在,它们在漫长的进化过程中如何应对灾难性环境、针对随时可能遭遇的不同胁迫环境因子形成了怎样的分子适应机制，是近年来倍受关注但仍未诠释的问题之一。由于蓝藻与高等植物叶绿体在进化上密切相关，搞清楚这类生物适应不同胁迫环境因子的分子基础及其作用机制，对从进化的角度理解光合生物与环境相互作用、通过同源性发现作物抗逆育种新靶标，有重要的理论和实践意义。 逆境应答蛋白的表达是细胞对逆境胁迫的主要适应机制之一。在特定的逆境条件下，细胞通常会表达一组蛋白质，用于识别与传递环境胁迫信号、稳定细胞内环境、消除并修复逆境造成的损伤等。因此，逆境应答蛋白的系统鉴定和功能确认，是揭示逆境条件下细胞代谢网络及抗逆性分子机制的关键。单细胞模式蓝藻基因组序列的确定，极大地推动了蓝藻细胞蛋白质组成模式研究，也为系统发掘蓝藻逆境应答蛋白、理解和揭示分子适应机制提供了新的切入点。Synechocystis 6803是第一个完成基因组测序的放氧光合模式生物。由于其具有易培养、可转化、对环境条件变化反应快等优点，以该藻种为材料所展开的逆境应答特别是盐胁迫蛋白质组研究方面已经取得了重要的进展，而对高pH胁迫的蛋白质组研究还鲜有报道。因此，本论文以Synechocystis 6803为材料，从分离纯化的亚细胞组分入手，采用蛋白质组学研究手段，对蓝藻细胞应答高pH胁迫的蛋白质代谢网络进行探讨。利用蔗糖密度离心和水溶性两相分离法相结合的方法，分别获得了对照（pH7.5）和处理（pH11）细胞的质膜、外膜和类囊体膜，并分别构建了包括可溶性蛋白和膜组分的一维和二维蛋白质凝胶电泳图谱。分析结果表明，高pH胁迫下质膜和可溶性蛋白蛋白组分的变化较外膜和类囊体膜蛋白组分更为明显。在考马斯亮兰染色胶上共发现有近110个蛋白点上调或下调表达，其中有82个蛋白点来源于质膜。对质膜蛋白进行的差异荧光标记双向电泳（2-D DIGE）分析结果与考马斯亮兰染色结果基本一致。对质膜上的82个蛋白点进行胶内消化和MALDI-TOF和MALDI-TOF/TOF质谱鉴定，得到了39个不同基因产物，其中25个是上调蛋白，14个是下调蛋白。在这些发生变化的蛋白中，近1/3是ABC型转运蛋白，如3个磷转运蛋白（Sll0679，Sll0683，Sll0684）均在高pH胁迫下明显上调。其它高pH响应蛋白包括参与光合作用（PsaF，Sll0819；CpcA，Sll1578）、呼吸作用（CoxB，Sll0813）以及细胞分裂过程的蛋白（MinD，Sll0289）。还有LexA repressor (Sll1626)和Guanylyl cyclase(Cya2，Sll0646)等起调控作用的蛋白质。此外发现8个高pH胁迫响应蛋白为功能未知的新蛋白。生物信息学预测结果显示，在已鉴定的质膜响应蛋白中有17个蛋白具有信号肽。6个蛋白为具有跨膜域的膜蛋白，其中的3个膜蛋白是首次被证明定位于质膜上，且其表达与高pH胁迫有关。这些研究结果对从分子水平理解蓝藻细胞主动应对高pH胁迫、维护细胞内pH相对稳定机制有重要启示。