Generation of Linear and Parabolic Concentration Gradients by Using a Christmas Tree-Shaped Microfluidic Network

This paper describes a simple method of generating concentration gradients with linear and parabolic profiles by using a Christmas tree-shaped microfluidic network.The microfluidic gradient generator consists of two parts:a Christmas tree-shaped network for gradient generation and a broad microchannel for detection.A two-dimensional model was built to analyze the flow field and the mass transfer in the microfluidic network.The simulating results show that a series of linear and parabolic gradient profiles were generated via adjusting relative flow rate ratios of the two source solutions(R_L~2≥0.995 and _PR~2≥0.999),which could match well with the experimental results(R_L~2≥0.987 and _PR~2≥0.996).The proposed method is promising for the generation of linear and parabolic concentration gradient profiles,with the potential in chemical and biological applications such as combinatorial chemistry synthesis,stem cell differentiation or cytotoxicity assays.     

块状纳米材料的设计理论研究

在二元共晶Spinodal系统中 ,Spinodal波长的大小随过冷度的增加而减少 ,并存在一个最小的波长 ,此时合金的生长速度最快 .提出当过冷度足够大时 ,液态Spinodal的波长进入到纳米尺度 ,形成块状纳米材料 .由于液态的扩散较易发生 ,当波长为纳米量级时 ,Spinodal的转变时间为微秒量级 .由于液体表面张力等的影响 ,液态Spinodal的组织由网状变成微粒形态 .     

环境污染、内生人口增长与经济增长模型

通过把环境污染与生产总量联系起来,由消费物质多少及环境好坏、人口增长率大小这三个因素来确定效用,建立一个环境内生人口增长的经济增长模型,并按照微分方程的稳定性理论对模型进行了均衡分析和动态分析．     

块状纳米材料的制备实验研究

提出的块状纳米材料的形成模型可以预测和解释共晶合金的液态Spinodal相分离 ,以及发生的区域和组织 .当液态Spinodal相分离在瞬间发生后 .形成一种纳米材料 ,其晶界与晶粒结合较紧密 ,具有较好的性能 .对合金Fe90 B10 而言 ,当过冷度大于 4 1 6℃时 ,液态Spinodal相分离发生 ,并出现多重Spinodal分解 .晶粒尺寸为 2～ 3nm ,软磁性能为Br=1 .3 0T ,Hc=0 .0 1A/cm .