Electric Field-Induced Fluid Velocity Field Distribution in DNA Solution

We present an analytical solution for fluid velocity field distribution of polyelectrolyte DNA. Both the electric field force and the viscous force in the DNA solution are considered under a suitable boundary condition. The solution of electric potential is analytically obtained by using the linearized Poisson-Boltzmann equation. The fluid velocity along the electric field is dependent on the cylindrical radius and concentration. It is shown that the electric field-induced fluid velocity will be increased with the increasing cylindrical radius, whose distribution also varies with the concentration     

空心莲子草皂苷的提取工艺

确定空心莲子草皂苷最佳提取工艺。采用超声辅助法提取空心莲子草中的皂苷类化合物,通过正交试验确定了最佳提取工艺。以齐墩果酸为对照,采用分光光度法在570nm处测定其中的皂苷,回归方程为:y=1.904C+0.0054,r=0.9990。最佳工艺条件:即用60%的甲醇,固液比采用1:20,超声时间10min,超声功率80%,间歇提取2次。选出了空心莲子草皂苷的最佳工艺,用齐墩果酸标准品,采用分光光度法,操作简便,结果准确,为空心莲子草中皂苷含量测定的一种切实可行的方法。     

Are developed and emerging agricultural futures markets multifractal? A comparative perspective

Although there are many reports on the empirical evidence of the existence of multifractality in various financial or commodity markets in current literature, few can be found to compare the multifractal properties of emerging and developed economies, especially for agricultural futures markets in those countries (regions). We therefore chose China as the representative of the transition and emerging economies, and USA as the representative of developed ones. We attempt to find the answers to the following questions: (1) Are all those different markets multifractal? (2) What are the dynamical causes for multifractality in those markets (if any)? (3) Are the multifractality strengths in those markets of the transition and emerging economies weaker (or stronger) than those of the developed ones? To answer these questions, Multifractal Detrended Fluctuation Analysis (MF-DFA) are applied to study some of the representative agricultural futures markets in China and USA, namely, wheat, soy meal, soybean and corn. Our results suggest that all the markets of China and USA exhibit multifractal properties except US soybean market, which is much closer to mono-fractal comparing with China’s soybean market. To investigate the sources of multifractality, shuffling and phase randomization procedures are applied to destroy the temporal correlations and non-Gaussian distributions respectively. We found that multifractality can be mainly attributed to the non-Gaussian probability distribution and secondarily to the nonlinear temporal correlation mechanism for all the markets, except US soybean and soy meal, which derives from some other unknown factors. Furthermore, the average of τ(q) are applied to obtain the multifractal spectra of the two markets as a whole. The results show that the width of the multifractal spectrum of US agricultural futures markets is significantly narrower than that of China’s. Based on our findings, we proposed a hypothesis that the strength of multifractality in developed economies may be weaker than that in emerging and transition ones.     

适配体筛选方法研究进展

利用指数富集配体进化技术(SELEX)可获得与目标靶具有特异性结合能力的适配体(寡核苷酸).经过近20年的研究,适配体被证实可在科研及临床应用中部分取代抗体,是有很大发展前景的技术领域.适配体技术发展的     

Global Weak Solutions for Compressible Navier-Stokes-Vlasov-Fokker-Planck System

The one-dimensional compressible Navier-Stokes-Vlasov-Fokker-Planck system with density-dependent viscosity and drag force coefficients is investigated in the present paper. The existence, uniqueness, and regularity of global weak solution to the initial value problem for general initial data are established in spatial periodic domain. Moreover, the long time behavior of the weak solution is analyzed. It is shown that as the time grows, the distribution function of the particles converges to the global Maxwellian, and both the fluid velocity and the macroscopic velocity of the particles converge to the same speed.