Theory and simulation of electrolyte mixtures

Monte Carlo simulation and theoretical results on some aspects of thermodynamics of mixtures of electrolytes with a common species are presented. Both charge symmetric mixtures, where ions differ only in size, and charge asymmetric but size symmetric mixtures at ionic strength ranging generally from I = 10^?4 to 1.0 M, and in a few cases up to I = 2 M, are examined. The theoretical methods explored are: (i) the symmetric Poisson-Boltzmann theory, (ii) the modified Poisson-Boltzmann theory and (iii) the hypernetted-chain integral equation. The first two electrolyte mixing coefficients w ₀ and w ₁ of the various mixtures are calculated from an accurate determination of their osmotic pressure data. The theories are seen to be consistent among themselves, and with certain limiting laws in the literature, in predicting the trends of the mixing coefficients with respect to ionic strength. Some selected relevant experimental data have been analysed and compared with the theoretical and simulation trends. In addition the mean activity coefficients for a model mimicking the mixture of KC1 and KF electrolytes are calculated and hence the Harned coefficients obtained for this system. These calculations are compared with the experimental data and Monte Carlo results available in the literature. The theoretically predicted Harned coefficients are in good agreement with the simulation results for the model KC1-KF mixture.     

Novel PLGA Microspheres for Sustained Delivery of Antisense Oligonucleotide

Novel poly(lactide-co-glycolide acid)(PLGA) microspheres were developed for sustained delivery of antisense oligonucleotide(ASO). First, a new cationic agent, polyethylenimine(PEI) conjugated to linoleic acid(LA)(PEI-LA) was synthesized by reacting PEI(M_w=800) with linoleoyl chloride. Then, PEI-LA was combined with LOR-2501 to form electrostatic complexes at moderate nitrogen-to-phosphate(N/P) molar ratios which were then encapsulated into poly(lactide-co-glycolide) microspheres by a multiple emulsion-solvent evaporation technique. With an increase in ASO/PEI-LA concentration from 5% to 10%, encapsulation efficiency of ASO in the microspheres reduced from 72.14% to 57.62%, and the particle size of microspheres increased from 28.58 μm to 34.76 μm. In vitro studies show that the release profile of ASO from microspheres prepared at 7.5% ASO-PEI-LA lasted for 14 d. The novel microspheres have a potential use as a sustained release vehicle for ASO.     

Development of an Artificial Compressibility Methodology with Implicit LU-SGS Method

A numerical method has been developed to solve the steady and unsteady incompressible Navier-Stokes equations in a two-dimensional, curvilinear coordinate system. The solution procedure is based on the method of artificial compressibility and uses a third-order flux-difference splitting upwind differencing scheme for convective terms and second-order center difference for viscous terms. A time-accurate scheme for unsteady incompressible flows is achieved by using an implicit real time discretization and a dual-time approach, which introduces pseudo-unsteady terms into both the mass conservation equation and momentum equations. An efficient fully implicit algorithm LU-SGS, which was originally derived for the compressible Eulur and Navier-Stokes equations by Jameson and Toon [1], is developed for the pseudo-compressibility formulation of the two dimensional incompressible Navier-Stokes equations for both steady and unsteady flows. A variety of computed results are presented to validate the present scheme. Numerical solutions for steady flow in a square lid-driven cavity and over a backward facing step and for unsteady flow in a square driven cavity with an oscillating lid and in a circular tube with a smooth expansion are respectively presented and compared with experimental data or other numerical results.     

On inverses and algebraic loops of co-H-spaces

In this paper we study the properties of homotopy inverses of comultiplications and algebraic loops of co-H-spaces based on a wedge of spheres. We also investigate a method to construct new comultiplications out of old ones by using a group action. We are primarily interested in the algebraic loops which have inversive, power-associative and Moufang properties for some comultiplications.     

光纤近红外光谱法在中草药分析中的应用——甘草中甘草酸含量的测定

提出光纤近红外光谱技术在线和快速检测中药甘草中有效成分甘草酸含量的方法。对含甘草酸浓度在0.94%～3.06%内的甘草,根据其在10 000～4 000 cm-1的近红外吸收光谱, 采用偏最小二乘算法(PLS)和主成分回归算法(PCR)建立了校正模型,比较了光谱不同前处理方法对校正结果的影响,当采用数据标准化并求一阶导前处理时可较好提取中药复杂体系的信息。当采用PLS算法时,校正集相关系数为0.958,校正集标准偏差(SEC)为0.179,验证集标准偏差(SEP)为0.197,PLS算法优于PCR算法。该方法快速和简便,适合于中药有效成分在线监控。     

PREDICTION OF NON-CAVITATING UNDERWATER PROPELLER NOISE

Non-cavitation noise of underwater propeller is numerically investigated. The main purpose is to analyze non-cavitation noise in various operating conditions with different configurations. The noise is predicted using time-domain acoustic analogy and boundary element method. The flow field is analyzed with potential-based panel method, and then the time-dependent pressure data are used as the input for Ffowcs Williams-Hawkings formulation to predict the farfield acoustics. Boundary integral equation method is also considered to investigate the effect of ducted propeller. Sound deflection and scattering effect on the duct is considered with the BEM. The governing equations are based on the assumption that all acoustic pressure is linear. A scattering approach is applied in which the acoustic pressure field is split into the known incident component and the unknown scattered component. Noise prediction results are presented for single propeller and ducted propeller in non-uniform flow conditions similar to real situation. The investigation reveals that the effect of a duct on the acoustic performance propeller is small in the far field under non-cavitating situations since the noise directivities of single and ducted propellers are almost the same. Only the high order BPFs are influenced by the existence of the duct.     

自由曲面光学透镜注射成型误差因素研究

自由曲面光学透镜注射成型误差对其光学性能将产生直接影响。注射成型过程中，注射工艺参数组合的优劣，直接影响成型误差的大小。为了获得高精密度的光学元件，就热塑性塑料的注射温度、模具温度、注射压力、保压压力及保压时间等主要工艺参数，对注射成型误差的影响进行综合研究,并且进行了实验验证。研究结果表明：适当提高注射温度与模具温度，同时采用高压注射、高压保压以及快速保压工艺，可显著降低注塑工件的体积收缩率，显著提高面形精密度，其光学表面面形误差小于0.1μm。可为注射工艺设计提供合理的依据。     

Application of the Model for Thermal Transport in Tokamaks

The anomalous electron thermal transport model baaed on collisionleas plasma instabilities driven by electron temperature gradient is applied to tokamak plasma with auxiliary heating. The steady state electron equation is solved and the results ahow good agreement with experimental observations including the principle of profile consltency, various scaling laws, and even some results for detached plasmas.