Experimental study of thermocapillary convection on a liquid bridge consisting of fluid with low Prandtl number in a floating half-zone

A device of mercury liquid bridge of floating half-zone is designed to experimentally explore thermocapillary convection and its instability of a low Prandtl number liquid. Noncontacted diagnostic techniques were developed to monitor surface flow and surface deformation. The surface flow and the influence of a growing surface film (or skin) on the flow were observed. It is shown that the film is a key factor in changing the behavior associated with the thermocapillary convection. The experiment indicates that the critical Marangoni number should be much higher than that expected by the numerical simulation. The condition and process of surface film growth are discussed. The surface oscillation of the mercury bridge wrapped with ''dirt-film'' was observed, and the characteristics and the frequency associated with this oscillation are given.

Cr^3＋，Yb^3＋，Er^3＋共掺磷酸盐铒玻璃转镜调Q激光性质研究

研究了Cr^3＋，Yb^3＋，Er^3＋共掺磷酸盐铒玻璃转镜调Q激光性质．三种Er2O3掺杂浓度的激光实验结果表明，在Er2O3名义掺杂浓度为0．5wt％时，玻璃的综合激光性质最好，重复频率为0．1Hz时，它的激光阈值功率为14．5mJ，最大输出能量为9．6mJ，斜率效率为0．55％．在同种实验条件下，比较了Cr14和Kigre公司生产的QE-7S激光性质参数，实验表明，前者激光阈值功率稍低，而后者的斜率效率和最大输出功率略高．

Methylation and gene mutation in eukaryotic DNA

5-methylcytosine (m(5)C) as a rare base exists in eukaryotic genomes, which is a normal constitution in many eukaryotic DNA and the existence of m(5)C is a feature of eukaryotic DNA. Under regular physiological conditions, cytosine of eukaryotic DNA is usually methylated. Up to the present, many people consider that the m(5)C may be mutation hotspots by the deamination leading to gene mutation. Our study indicated that the spontaneous mutation caused by the transition of G.C --> A.T, in eukaryotic DNA, may result from the tautomer changing of base pairs and may also be cause by other factor actions, however it could not be caused by the deamination of m(5)C.

氮化镓材料的外延生长及性质研究

Submitted by zhangdi (zhangdi@red.semi.ac.cn) on 2009-04-13T11:45:31Z

表面应力诱导InGan量子点的生长及其性质

为了得到高性能的GaN基发光器件，有源层采用MOCVD技术和表面应力的不均匀性诱导方法在生长了InGaN量子点，并通过原子力显微镜（AFM），透射电子显微镜（TEM）和光致发光（PL）谱对其微观形貌和光学性质进行了观察和研究，AFM和TEM观察结果表明

用于洁净核能源的ADS-EA方案

加速器驱动系统 (ADS)是一种新型的洁净能源装置 ,它采用加速器提供的强流高能量质子束驱动次临界的核反应堆 ,既有安全可靠和产生核废料少的优点 ,还可以处理传统反应堆留下的核废料 .能量放大器是一个基于回旋加速器组合的 ADS方案 ,由三级回旋加速器组成的加速器系统可以产生流强为 1 2 m A和能量为 1 .2 Ge V的质子束 (束流功率 1 4.4MW) ,用以驱动 1 50 0 MW的核反应堆 .

平面几何问题解决过程中的元认知实验研究

This study was based on the cognitive-metacognitive model of mathematical problem solving established by Lester & Garofalo(1985). The method of protocal analysis was used and 19 excellent students(9 male and 10 female) & 19 learning-disabled students(11 male and 8 female) in middle school(grade 3)were tested and interviewed during they solved plane geometry problems. The main results showed as follows: (1) There was a significant difference between excellent students and learning-disabled students on time-assignment when they solved plane geometry problems. Excellent students used more time on phase organization and less time on phase execution. There was no difference on phases orientation and verification. (2) Excellent students showed higher metacognitive level than learning-disabled students. The deference existed in phases orientation and organization. Excellent students reported more metacognitive sentences in phases orientation and organization than learning-disabled students. They had more self-awareness and goal-awareness. They had more "knowledge about what they know" and "knowledge about what they should use". They designed more globle goal and subgoals and made more self-evaluation. (3) Both the excellent students' and learning-disabled students' self-checking level should be improved.