X-ray observations of tungsten wire array Z-pinch implosions on QiangGuang-1 facility

Z-pinch experiments with two arrays consisting, respectively, of 32 4-μm- and 6-μm-diameter tungsten wires have been carried out on QiangGuang-1 facility with a current rising up to 1.5MA in 80ns. At early time of implosion, x-ray framing images show that the initial emission comes from the central part of arrays, and double clear emission rings, drifting to the anode and the cathode at 5×10⁶cm/s and 2.4×10⁷cm/s respectively, are often produced near the electrodes. Later, in a 4-μm-diameter tungsten wire array, filamentation caused by ohmic heating is prominent, and more than ten filaments have been observed. A radial inward shift of arrays starts at about 30\,ns earlier than the occurrence of the x-ray peak power for both kinds of arrays, and the shrinkage rate of emission region is as high as 1.7×10⁷cm/s in a 4-μm-diameter tungsten wire array, which is two times higher than that in a 6-μm one. Emission from precursor plasmas is observed in implosion of 6-μm-diameter tungsten wire arrays, but not in implosion of a 4-μm-diameter tungsten wire array. Whereas, in a 4-μm-diameter tungsten wire array, the soft x-ray emission shows the growth of m=1 instability in the plasma column, which is caused by current. The reasons for the discrepancy between implosions of 4-μm- and 6-μm-diameter tungsten wire arrays are explained.     

CsI(Tl)闪烁晶体研究进展

CsI(Tl)闪烁晶体光产额高于BGO晶体4倍多,辐照长度较NaI(Tl)晶体短,机械性能好,是一种优良实用的闪烁晶体材料.CsI(Tl)晶体的发光中心包括激活剂发光中心[Tl(Ⅰ)和Tl(Ⅱ)]和辐照诱导缺陷发光中心.CsI(Tl)晶体的发射谱峰值位于550nm,能与硅光二极管配合组成性能优良的探测器,广泛应用于核技术和高能物理等领域.目前主要采用坩埚下降法和连续加料法生长.本文综述了CsI(Tl)闪烁晶体的生长、缺陷、闪烁性能及其应用领域的研究与发展趋势.     

NaF饮水喂养的小白鼠肝脏线粒体代谢热化学研究

利用 L KB2 2 77生物活性检测系统 ,测定了用含不同浓度 Na F饮水喂养的小白鼠肝脏线粒体代谢热曲线 ,实验表明 ,饮水中 Na F浓度增加 ,最大热功率增大 ,代谢产热增加 ,停滞期和活性维持时间缩短 .热曲线测定完毕后的样品 ATP浓度分析表明 ,随着 Na F浓度增加 ,系统的 ATP浓度降低 .结合透射电镜对肝细胞超微结构研究结果 ,根据化学渗透假说对实验结果进行了比较完满的解释     

Microstructure of polymers obtained by cationic polymerization of endo-dicyclopentadiene

endo-Dicyclopentadiene (DCPD) was polymerized by various cationic initiating systems in different solvents. IR and ¹H NMR results show that four types of structural units are formed due to the corresponding addition modes: the addition on the norbornenic (NB) double bond generates unit I and rearranged unit II, while the addition on the cyclopentenic (CP) double bond produces unit III and rearranged unit IV. The reaction medium has a stronger effect on the microstructure of the polymer (PDCPD) than initiating systems. The polymers prepared in toluene and n-hexane contain all four structural units, while the polymer produced in methylene chloride is composed of structural units II and IV. © 1996 John Wiley & Sons, Inc.     

微波促进环境友好条件下，碳酸二甲酯为甲基化试剂合成二甲基化1,6-二氢嘧啶酮

本文报道以碳酸二甲酯（DMC）为甲基化试剂实现3，4-二氢嘧啶-2-硫酮甲基化反应的有效方法。在微波辐射下，弱碱MgO和四丁基溴化胺的存在下反应即可完成得到目标产物。DMC的使用避免了剧毒烷基化试剂—碘甲烷或硫酸二甲酯的使用，微波技术的使用极大的缩短了反应时间。通过元素分析、¹H NMR,IR 和单晶X射线衍射确证了它们的结构，提出了反应机理。     

Effects of fiber orientation on the stress distribution in model composites

A Raman-mechanical technique was used to study the relationship between stress distribution and fiber orientation in model composites. Our experimental data generally were consistent with most simplistic mechanical models. A more complete analysis, using the Eshelby equivalent inclusion method, fitted our experimental data exceptionally well. For large applied strains, compressive failure occurred for fibers which were oriented at high angles relative to the draw direction. This occurred because of the lateral shrinkage associated with the matrix when the sample was stretched. The effect of fiber end geometry on the stress distribution for these misaligned fibers was the same as observed earlier. Tapered-end fibers generally carried loads more efficiently in composites than blunt-end fibers.     

随机需求下闭环供应链协调的收入费用共享契约研究

从供应链的角度,可持续发展的基本要求就是由"资源—生产—消费—废弃"的单向开环供应链到"资源—生产—消费-再生资源"闭环反馈式供应链的转化,基于废旧产品再制造的闭环供应链问题近几年引起学者的广泛重视。本文研究了随机市场需求下,制造商生产产品,零售商在销售产品的同时负责从消费者手中回收费旧品,制造商将回收的费旧品进行再制造后重新进入销售渠道的二阶闭环供应链,运用Stackelberg博弈理论分析了闭环供应链节点企业的决策问题,在分析传统收入共享契约的基础上提出了收入费用共享契约实现了闭环供应链的协调问题,最后通过一个实际算例进行了论证。     

High-quality polythiophene films prepared by electropolymerization of thiophene in BF3-ethyl ether solution

Polythiophene films have been deposited on a platinum electrode surface by direct oxidation of thiophene in BF₃-ethyl ether solution containing a controlled amount of water (5 mM). The electric and mechanical properties of the films were studied. Experimental results demonstrated that the films prepared at low applied potentials were semiconductors with conductivities in the order of 10^?1 s cm^?1. The strengths of these films were high and comparable to those of some widely used engineering plastics such as poly(propylene) and poly(vinyl acetate). The conductivities of the PT films varied with the value of applied potential used for electrolysis and passed through a maximum of 19.13 s cm^?1 at +1.6 V. At a given applied potential, low experimental temperature, and monomer concentration led to formation of films with high quality. © 1995 John Wiley & Sons, Inc.     

亚微米级Ag2S空心球的乳液法合成

Hollow Ag₂S spheres have been prepared via hydrolyze reaction of Ag₂S₂O₃， which formed from the reaction of AgNO₃ with Na₂S₂O₃， in cyclohexane/water/polyglycol emulsion system. It was found that the component of the reaction system has a significant influence on the formation of hollow Ag₂S spheres. The possible formation mech-anism of the hollow Ag₂S spheres in the emusion system was also discussed.