泥沙运动的受力分析——关于碰撞力的讨论

本文以单颗粒为体系和以固相的拟流体微团为体系分别对泥沙运动进行了受力分析,给出了体系的力平衡方程,并证明了两种方程是相容的。通过对比说明,同一个力采用不同的体系分析时分属于不同类型,例如,流体-颗粒间的作用力在前一体系中属于表面力,在后一种体系中属于彻体力;拟流体分析中的表面力(应力),在单颗粒体系的力平衡中根本不出现等等,由此清楚地表明进行受力分析和建立力平衡方程时明确所研究体系的重要性。本文还详细分析了对于上述两种体系,颗粒-颗粒碰撞对体系运动所起的作用,以及在运动方程中的体现,并指出:泥沙运动力学中经常使用的“碰撞力”在概念上是含糊的,计算碰撞力的表达式的根据是可疑的

Accumulation of Rare Earth Elements in Spinach and Soil under Condition of Using REE and Acid Rain Stress

The content and distribution characteristics of REE in spinach and soil under using REE and acid rain stress were studied by pot experiments. The results show that the content of REE is 0.527～0.696 (μg·g - 1) in the above2ground portion of spinach , 21668～31003 (μg·g - 1) in the under2ground portion of spinach and 229109～ 250130 (μg·g - 1) in the soil . With the acidity of acid rain increasing , the leaching of REE in plants and soil is strengthened and the amount of REE reduces with decreasing of pH value . After REE are used , though plants show the selective absorption to Ce group elements (especially spraying on leaves) , regardless under acid rain stress or using REE or not , the distribution model of REE in the above2ground and under2ground portion of plants is basical2 ly the same with the control . Plants also follow the Oddo2Harkins rule of the REE of distribution abundance , light rare earth elements is enriched , the minus of Eu is abnormal and admeasure of Ce is a rich model . The results show that REE in plants mainly come from soil and are affected by it

高压段含有颗粒的含灰气体激波管流动数值模拟

本文给出了用类特征线法计算的高压室含灰的无限长激波管非平衡流动解。以膜压比ｐ４１＝５．０、高压室含灰的体积分数α４＝０．０１为例，详细分析了非平衡流场，并同冻结流解和平衡流解作了详细的对比分析，清楚地显示了含灰气体激波管非平衡流动从冻结流向平衡流过渡的各种细节，说明了基于冻结声速的非平衡流类特征线法计算何以能得到无限趋近于平衡流解的原因。本文的结果表明，类特征线方法可以提供非常精细的气－固二相流非平衡流场结构

关于一维非定常气─固二相流特征理论的讨论

本文研究了一维非定常气－团二相流的特征，对于目前常用的、包含一定近似的运动方程组，它有两个虚部很小的复根，研究表明这种很小的虚部出现与方程中引入的近似有关。从十多个算例的结果看，这样的虚部不影响人们在工程计算中用该方程组求解初值问题。针对具有上述特征的气－团二相流方程组，本文发展了一种类特征线方法，它保留了双曲型方程特征线方法的若干优点，但它允许方程的特征根中有微小的虚部。含灰气体激波管流动的计算表明，类特征线法具有精度高、数值耗散和弥散小等优

BIOACCUMULATION OF CADMIUM ION

［中文文摘］研究了表达外源特异性Cd2+转运系统的基因工程菌E.coliTOP10F’对Cd2+的富集行为。重组菌获得了比宿主菌高6倍的Cd2+富集能力,而且富集行为受pH变化的影响也大为降低。Na+、Mg2+以及Cu2+、Hg2+、Pb2+和Ni2+等共存离子的存在都对重组菌的Cd2+富集产生抑制,其中Cu2+的抑制作用最强,Ni2+最弱。EDTA的存在严重影响重组菌对Cd2+的生物富集,但柠檬酸的影响却很小。［英文文摘］Escherichia coli TOP10F’ was genetically engineered to express a Cd2+ transport system for the evaluation of its Cd2+ bioaccumulation from aqueous solution. A six-folds increase of Cd2+ uptake was obtained by the recombinant bacteria compared with the original host strain. Within the test of pH range (4~9), the recombinant cells showed high resistance to pH variation, retaining up to 9mg/g of Cd2+ bioaccumulation. The presence of Na+, Mg2+, Cu2+, Pb2+, Hg2+ and Ni2+ inhibited Cd2+ uptake to different extents, respectively, with the effect of Cu2+ being most significant and Ni2+ being slightest. The existence of 2mmol/L Citric acid didn't influence Cd2+ bioaccumulation remarkably, while 0.1mmol/L EDTA resulted in more than 90% loss of Cd2+ binding capacity, suggesting EDTA could exert a severe adverse effect on Cd2+ uptake by recombinant strain.浙江省自然科学基金(M203130); 2003年教育部优秀青年教师资助计划