Study on the mixing of fluid in curved microchannelswith heterogeneous surface potentials

In this paper the mixing of a sample in the curved microchannel with heterogeneous surface potentials is analysed numerically by using the control-volume-based finite difference method. The rigorous models for describing the wall potential and external potential are solved to get the distribution of wall potential and external potential, then momentum equation is solved to get the fully developed flow field. Finally the mass transport equation is solved to get the concentration field. The results show that the curved microchannel has an optimized capability of sample mixing and transport when the heterogeneous surface is located at the left conjunction between the curved part and straight part. The variation of heterogeneous surface potential $\psi_{\rm n}$has more influence on the capability of sample mixing than on that of sample transport. The ratio of the curved microchannel's radius to width has a comparable effect on the capability of sample mixing and transport. The conclusions above are helpful to the optimization of the design of microfluidic devices for the improvement of the efficiency of sample mixing.     

Research on nucleation and coagulation of nanoparticles in parallel twin jets

The large eddy simulation method has been used to simulate the diffusion of H2SO4 vapor in the parallel twin jets.The distributions of number concentration and size of nanoparticles produced by nucleation and coagulation in sulfuric acid/water system are given.The functions of the sulfur content,relative humidity and jet Reynolds number are evaluated according to the distributions of number concentration and size of nanoparticles.The results show that the nucleation in sulfuric acid/water system produces large number of nanoparticles ,and gas-to-nanoparticle conversion mostly takes place in the middle and interface of the twin jets.The coagulation process of particles reduces the number concentration,while increases the mean particle size.For the case with higher sulfur content,more number and smaller size nanoparticles are produced by nucleation and coagulation.There is also a larger number of nanoparticles for the cases with higher relative humidity and jet Reynolds number.     

带有半埋藏空间裂纹的Cr12构件电磁热止裂分析

对带有半埋藏环形裂纹的Cr12标准拉伸试件进行了电磁热止裂研究.通过ZL-2型放电装置实现了半埋藏空间裂纹的止裂实验,采用微机控制电子万能试验机完成了止裂前后试件拉伸性能测试,同时计算了电磁热止裂前后应力强度因子的变化;建立了超强脉冲电流放电瞬间,环形裂纹尖端附近电流绕流、温度场和热应力场的数值分析模型,通过热-电耦合和热-机械耦合两个过程得到了脉冲放电瞬间拉伸试件中的电流矢量场、温度场和热应力场.研究表明:脉冲电流放电瞬间,围绕裂纹尖端金属熔化,钝化了裂尖,并围绕裂尖形成了热压应力场,得到了超细化的金属组织,止裂后抗拉强度得到了提高,达到了止裂的目的.     

关于K~+介子和核子的弹性散射

本文用塔姆-唐可夫近似解K~+介子和核子的弹性散射问题,得到了K介子实验室动能400Mev以下的相移截面和能量的关系,并和实验及前人的理论结果作了比较。计算中较严格考虑了核子反冲效应,指出了在考虑了反冲效应后能使理论曲线在高能端更与实验曲线接近。同时就-K和∑-K的各种可能的宇称情况进行了分析,排斥了相对宇称皆正的可能,并指出-K和∑-K的相对宇称选取不同的符号和二者皆取负号一样,能符合K~+-P散射实验,但在分析K~+-n 散射时仍遇到困难。     

ICP-AES雾化法氢化法联合测定白族产妇及新生儿发中常微量元素

本文报道用ICP-AES同时测定人发中24种元素的方法。采用10mg/ml样品,4.8mol/L盐酸溶液,用基体匹配法校正干扰,分别用雾化法和氢化法测定,用人发标准检验方法和结果的准确性。较满意地测定了Zn等18种元素。91例母婴发中的Zn、Fe、Sr、Mg、Cd、P、Ni、Se、As和Mo等元素呈显著的正相关性。     

鬼灯擎素的结构分析

本文报道了从鬼灯擎(Rodgersid aesculifolia Batal)中提取的鬼灯擎素(Bergenin)晶体的结构研究。鬼灯擎素晶体为正交晶系,C_(14)H_(18)O_(10),M_r=346.28,其晶胞参数a=7.468(9),b=13.899(4),c=14.228(0)A;空间群为P2_12_12_1;晶胞内分子数Z=4,D_c=1.5560g/cm~3,结构模型由SHELXTL程序解出;经Fourier合成和最小二乘修正,最后的偏离因子R=0.028。此外,利用晶体结构分析所得分子中各原子的坐标,以半经验分子轨道法CNDO/2程序计算了分子总能量、净电荷分布以及Wiberg键级等,并以此讨论了分子的反应活性中心。