The Interaction Between Shock Waves and Foam in a Shock Tube

An experimental study and a numerical simulation were conducted to investigate the mechanical and thermodynamic processes involved in the interaction between shock waves and low density foam. The experiment was done in a stainless shock tube (80mm in inner diameter, 10mm in wall thickness and 5360mm in length). The velocities of the incident and reflected compression waves in the foam were measured by using piezo-ceramic pressure sensors. The end-wall peak pressure behind the reflected wave in the foam was measured by using a crystal piezoelectric sensor. It is suggested that the high end-wall pressure may be caused by a rapid contact between the foam and the end-wall surface. Both open-cell and closed-cell foams with different length and density were tested. Through comparing the numerical and experimental end-wall pressure, the permeability coefficients a and 0 are quantitatively determined.

气泡初始尺寸对泡-弹状流型转换的影响

本文对气液两相泡状流向弹状流转换的机制进行了分析,认为气泡合并是影响该流型转换的主要机制,并据此用随机数值模拟方法,对气泡初始尺寸对泡状流向弹状流转换的影响进行了研究.计算结果表明,无量纲气泡碰撞率是一条通用曲线,根据该曲线可以确定气泡初始尺寸产生影响的区域及其大小,与实验结果的比较令人满意.

Absorption characteristic and nonvolatile holographic recording in LiNbO3 : Cr : Cu crystals

The absorption characteristic of lithium niobate crystals doped with chromium and copper (Cr and Cu) is investigated. We find that there are two apparent absorption bands for LiNbO3:Cr:Cu crystal doped with 0.14 wt.% Cr2O3 and 0.011 wt.% CuO; one is around 480 nm, and the other is around 660 nm. With a decrease in the doping composition of Cr and an increase in the doping composition of Cu, no apparent absorption band in the shorter wavelength range exists. The higher the doping level of Cr, the larger the absorbance around 660 nm. Although a 633 nm red light is located in the absorption band around 660 nm, the absorption at 633 nm does not help the photorefractive process; i.e., unlike other doubly doped crystals, for example, LiNbO3:Fe:Mn crystal, a nonvolatile holographic recording can be realized by a 633 nm red light as the recording light and a 390 nm UV light as the sensitizing light. For LiNbO3:Cr:Cu crystals, by changing the recording light from a 633 nm red light to a 514 nm green light, sensitizing with a 390 nm UV light and a 488 nm blue light, respectively, a nonvolatile holographic recording can be realized. Doping the appropriate Cr (for example, N-Cr = 2.795 X 10(25)m(-3) and N-Cr/N-Cu = 1) benefits the improvement of holographic recording properties. (c) 2005 Optical Society of America.

一些化学因素对导管分子分化的影响

本文主要以莴苣髓部外植体为材料研究了激素，多胺，一些糖和氨基酸及丁酸钠，二甲亚砜对导管分子分化的影响，结果表明，生长素、细胞分裂素和糖是外植体中导管分子分化调控中的关键因素。生长素和细胞分裂素可能是导管分子分化诱导因子。糖可能有两方面的作用：提供壁合成原料和提供分化所需能量。多胺可以部分取代细胞分裂素的作用。游离羟脯氨酸抑制了外植体细胞分裂和导管分子分化。与壁代谢有关的木糖，苯丙氨酸对导管分子分化有促进作用，说明细胞壁合成的调节机制是分化调节机制中的—部分。本实验还发现乙烯的生物合成与导管分子分化也有部分关系。赤霉素、果糖、甘露糖对导管分子分化有抑制作用。丁酸钠、二甲亚砜对导管分子分化也有一定影响。此外，本文也对细胞分裂与导管分子分化的关系，导管分子分化与培养时间，形态结构间的关系进行了一些初步的探。

核辐射探测器及其制作工艺

本发明主要涉及一种核辐射探测器，尤其涉及在高能物理和核物理中使用的位置灵敏探测器及其制作工艺。一种核辐射探测器，包括有硅基片，Ｎ型，其主要特点是还包括有探测窗口（１）由相互平行的多个探测窗口（１）组成，有Ｂ↑［＋］掺杂区（３），形成ＰＮ结，其上有Ａｌ层（２），并设有引线（７）；两探测窗口（１）之间设有绝缘分割区（４）；硅基片背面有Ｐ↑［－］掺杂区（５），形成Ｎ↑［＋］欧姆接触，其上复有Ａｌ层（６），形成背电极。本发明的核辐射探测器具有优良的电特性和探测特性。在核物理实验中能同时测量核反应产物的能量和位置（角分布）信息，在得到非常好的位置分辨的同时得到相当好的能量分辨率。由于在工艺流程中严格控制和严格操作，采取特殊Ｃｌ离子处理，减少了ＳｉＯ↓［２］层中的正电荷。并减少了ＳｉＯ↓［２］－Ｓｉ界面附近的表面态，使探测器的反向漏电流比其他工艺例如面垒工艺制备的探测器下降１～２个量级，达到ｎＡ量级。

定量ELISA检测小鼠血清中抗LDH-C4IgG2b抗体的水平

用定量EL ISA 的方法检测背部携带分泌抗LDH - C4 IgG2b 抗体杂交瘤小鼠的血清中IgG2b 抗体浓 度, 结果表明: 本法稳定, 批间变异系数为7104 %～13130 % , 批内变异系数为3161 %～10120 %; 标准曲线 相关性良好, 相关系数从01962 884～01996 795 ; 灵敏度较高, 最低检出浓度为0101 mg/ L ; 特异性亦较好.

干旱区微小生物结皮中藻类研究的新进展

微小生物结皮是干旱区环境保护和生态恢复中新的研究热点之一,藻类在其早期形成和强度维持中起着不可替代的重要作用。文中以作者近年研究内容为重点,综合相关领域的最新研究进展,对微小生物结皮的精细结构、发育、藻类生物量的表示方法、影响因素、垂直分布、演替、固土效应、胶结机理及胞外代谢产物等作了较全面的评述,并提出该领域未来研究的主要方向。