Microgravity experiments of two-phase flow patterns aboard Mir Space Station

A first experimental study on two-phase how patterns at a long-term, steady microgravity condition was conducted on board the Russian Space Station "MIR" in August 1999. Carbogal and air are used as the liquid and the gas phase, respectively. Bubble, slug, slug-annular transitional, and annular hows are observed. A new region of annular how with lower liquid superficial velocity is discovered, and the region of the slug-annular transitional flow is wider than that observed by experiments on board the parabolic aircraft. The main patterns are bubble, slug-annular transitional and annular flows based on the experiments on board MIR space station. Some influences on the two-phase how patterns in the present experiments are discussed.

PLOD3基因3'调控区的人类特异突变改变miR-124a对PLOD3的调控

microRNAs(miRNAs)是一类在转录后水平调控基因表达的不编码蛋白质的小RNA(长度20-24个碱基).其中,miR-124a是一个在哺乳动物中枢神经系统高度表达的miRNA,在神经前体细胞向神经元分化的过程中起着举足轻重的作用.由于miRNAs特异性地识别靶基因的3'端调控区(3'UTR)的靶序列,因此,在人类起源过程中基因3'UTR的单核苷酸序列变异有可能导致miRNA调控的改变.通过靶基因预测和3'UTR区在哺乳动物代表物种间的同源序列比较,我们发现miR-124a的靶基冈中有一个基因(PLOD3)3UTR的靶位点中存在人类特异突变位点.利用体外报告基因系统,发现PLOD3基因3'UTR靶位点中所含的一个人类特异的突变导致miR-124a对PLOD3的调控效率降低.研究表明,miRNAs靶基因3'UTR的序列变异具有功能效应,它有可能足人类中枢神经系统在起源和演化中发挥关键作用的重要遗传机制之一.

二(2,4,4-三甲基戊基)单硫代膦酸-上胺205-正庚烷乳状液膜萃取分离钪(Ⅲ)、铁(Ⅲ)和镥(Ⅲ)

本文研究了外水相ｐＨ值、流动载体浓度、表面活性剂浓度、内相解析酸浓度、水乳比、油内比等因素对二（２，４，４－三甲基戊基）单硫代膦酸（Ｃｙａｎｅｘ３０２）－上胺２０５－正庚烷乳状液 膜迁移Ｓｃ（Ⅲ）的影响。在一定条件下，Ｓｃ（Ⅲ）可以快速而完全地迁移，有可能实现Ｓｃ（Ⅲ）与Ｆｅ（Ⅲ）、Ｌｕ（Ⅲ）的分离。

异丙基膦酸单(1-己基-4-乙基)辛酯上胺205-正庚烷乳状液膜分离钪(Ⅲ)、铁(Ⅲ)、镥(Ⅲ)

本文研究了异丙基膦酸单（１－己基－４－乙基）辛酯（简称ＰＴ－２）上胺２０５－正庚烷乳状液膜分离钪（Ⅲ），铁（Ⅲ），镥（Ⅲ）及外相酸度、表面活性剂浓度、流动载体浓度和内相酸度对Ｓｃ（Ⅲ）、Ｆｅ（Ⅲ）、Ｌｕ（Ⅲ）迁移影响。实验结果表明，在一定的条件下Ｓｃ（Ⅲ）有可能实现与Ｆｅ（Ⅲ）、Ｌｕ（Ⅲ）的分离。

二(2,4,4-三甲基戊基)膦酸-上胺205-正庚烷乳状液膜分离钪(Ⅲ)、铁(Ⅲ)和镥(Ⅲ)

本文研究了二（2，4，4-三甲基戊基）膦酸（Cyanex272）-上胺205-正庚烷乳状液膜分离Sc（Ⅲ）、Fe（Ⅲ）和Lu（Ⅲ）。考察了外相酸度、表面活性剂浓度、流动载体浓度及内相盐酸浓度对Sc（Ⅲ）迁移的影响。并探讨了该液膜体系分离Sc（Ⅲ）、Fe（Ⅲ）和Lu（Ⅲ）的可能性，结果表明，该体系对于稀土矿中Sc（Ⅲ）的分离与分析有良好的应用前景。

Kinetic measurements of cell surface E-selectin/carbohydrate ligand interactions

Selectin/ligand interactions initiate the multistep adhesion and signaling cascades in the recruitment of leukocytes from circulation to inflamed tissues and may also play a role in tumor metastasis. Kinetic properties of these interactions are essential determinants governing blood-borne cells' tethering to and rolling on the vessel wall. Extending our recently developed micropipette method, we have measured the kinetic rates of E-selectin/ligand interactions. Red cells coated with an E-selectin construct were allowed to bind HL-60 or Colo-205 cells bearing carbohydrate ligands. Specific adhesions were observed to occur at isolated points, the frequency of which followed a Poisson distribution. These point attachments were formed at the same rate with both the HL-60 and Colo-205 cells (0.14 +/- 0.04 and 0.13 +/- 0.03 mum(2) s(-1) per unit density of E-selectin, respectively) but dissociated from the former at a rate twice as fast as did from the latter (0.92 +/- 0.23 and 0.44 +/- 0.10 s(-1), respectively). The reverse rates agree well with those measured by the flow chamber. The forward rates are orders of magnitude higher than those of Fc gamma receptors interacting with IgG measured under similar conditions, consistent with the rapid kinetics requirement for the function of E-selectin/ligand binding, which is to capture leukocytes on endothelial surfaces from flow.

Development Of Biosensor Based On Imaging Ellipsometry

The concept of biosensor based on imaging ellipsometry was proposed ten years ago. Its principle and the methodology as well as some solutions to problems which have to be faced during the development are mentioned. Its properties of phase sensitive, high throughput and fast sampling, as well as label-free, sensitivity better than 1 ng/ml for Immunoglobulin G, and real-time analysis for protein interaction process, etc. provide a potential for applications in biomedicine field. The recent biosensing development with total internal reflection imaging ellipsometry is presented also. [GRAPHICS] An example of 48 protein arrays in matrix. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Molecular dynamics studies on dislocations in crystallites of nanocrystalline alpha-iron

Molecular dynamics simulations have been carried our to study the atomic structure of the crystalline component of nanocrystalline alpha-iron. A two-dimensional computational block is used to simulate the consolidation process. It is found that dislocations are generated in the crystallites during consolidation when the grain size is large enough. The critical value of the grain size for dislocation generation appears to be about 9 nm. This result agrees with experiment qualitatively. AN dislocations that are preset in the original grains glide out during consolidation. It shows that dislocations in the crystallites we generated in consolidation process, but not in the original grains. Higher consolidation pressure results in more dislocations. Furthermore, new interfaces are found within crystallites. These interfaces might result from the special environment of nanomaterial. (C) 1998 Acta Metallurgica Inc.

Effective elastic modulus of bone-like hierarchical materials

A shear-lag model is used to study the mechanical properties of bone-like hierarchical materials. The relationship between the overall effective modulus and the number of hierarchy level is obtained. The result is compared with that based on the tension-shear chain model and finite element simulation, respectively. It is shown that all three models can be used to describe the mechanical behavior of the hierarchical material when the number of hierarchy levels is small. By increasing the number of hierarchy level, the shear-lag result is consistent with the finite element result. However the tension-shear chain model leads to an opposite trend. The transition point position depends on the fraction of hard phase, aspect ratio and modulus ratio of hard phase to soft phase. Further discussion is performed on the flaw tolerance size and strength of hierarchical materials based on the shear-lag analysis.

求解流体力学反问题的数学方法及应用

以亚、跨声速翼型设计问题为例，提出一种求解流体力学反问题的新方法。

积分式高压大电流互感器的基本原理和实验研究

本文提出了电流互感器的开路运行方式。利用积分电路得到了被测电流的实用计算公式,为工频和脉冲高压大电流的测量提供了一个新方法。该互感器体积小、重量轻、使用频带较宽。文中给出了参数选择原则、实验特性曲线和照片。

Parameter-transformation relations for traveling-wave solutions of kdv-burgers equation

 Burgers suggested that the main properties of free-turbulence in the boundless area without basic flow might be understood with the aid of the following equation, which was much simpler than those of fluid dynamics, 更多还原

Non-axisymmetric magnetostatic equilibrium with strong twisted component of magnetic field

The perturbation theory is applied further to the discussion of the equilibrium properties of a sunspot-like magnetic field with a strong twisted component. The basic state reduces to the usual one discussed extensively for the axisymmetric magnetostatic equilibrium with twisted component of magnetic field, and the perturbed state is described by two coupled equations. As the magnetic force-line is twisted, there is a magnetic tension in the azimuthal direction. In this case, the perturbed total pressure is no longer independent of the azimuthal variable θ, and the magnetic field in the dark penumbal fibril may be either stronger or weaker relatively.