Investigation of Three-liquid-phase Extraction Systems for Simultaneous Separation of Emodin and Rhein

Several three-liquid-phase extraction systems comprised of organic extractant,polymer and salt aqueous solution were applied to isolate and purify simulated herbal extract containing emodin and rhein.Some influential factors on the partitioning behaviors were studied.The results revealed that extractant type and solution pH value were crucial factors for improving the separation performance.The optimal separation results were obtained at pH 8.00 with methyl isobutyl ketone as the extractant,10%（ω） polyethylene glycol with the molecular weight 4000 Da,and 10%（ω） ammonium sulphate.Under the optimized conditions,95%emodin and 97%rhein were simultaneously extracted into the organic phase and polymer-rich phase from simulated herbal solution with the initial concentration of 100×l0^-6（ω）,respectively,and their separation factor of over 10000 was achieved.By adjusting pH value,back extraction rate of both emodin and rhein could be up to about 99%.With the assistance of molecular simulation program XLOGP3 and molecular orbital package,the possible mechanism of extraction was analyzed,and hydrophobic interaction and hydrogen-bonding interaction might be the major driving forces affecting the partitioning behaviors of emodin and rhein.     

CFD simulation of large-scale bubble plumes: Comparisons against experiments

Computational fluid dynamics (CFD) simulations have been carried out to simulate a turbulent, bubble plume in a liquid pool. A two-fluid enhanced k-? model has been used, with the extra source terms introduced to account for the interaction between the bubbles and the liquid and transient calculations have been performed to study the plume growth, the acceleration of the liquid due to viscous drag, and the approach to steady-state conditions. In order to obtain correct spreading of the plume observed experimentally, it was observed that interfacial forces like lift and turbulent dispersion plays important role. The sensitivity analysis for drag coefficient and two different turbulent dispersion forces is presented. The development of the flow variables has been compared with the experimental data. From the CFD predictions obtained in the present work, it can be concluded that a two-dimensional (2D) axisymmetric assumption in this case is justified, with 2D model predictions in good agreement with the experimental data and those of a three-dimensional (3D) model, except for the shear stresses and turbulent kinetic energy. In general, quantitative comparison with the experimental data has revealed that, by applying proper models of inter-phase momentum transfer, and performing simulations based on the two-fluid model, satisfactory predictions of mean flow quantities can be obtained for this application away from the injector.     

水平油气两相流中液滴分布的衰减系数

引　言在石油、天然气的开发过程中 ,在通常的操作条件下 ,水平管线中的两相分离流 (指分层流和环状流 )是常见的流动结构 在较高的气相流速时 ,液滴可从液膜表面上被撕破而进入到中心气核中去 .液滴和其携带流体间的相互作用和相间滑移的存在强烈地影响着流动时的压降特性 ,而液滴浓度在管截面上的不均匀分布 ,也影响气相速度的分布以及对相份额的准确计算和测量 .众所周知 ,管路的压降和相份额数据是两相或多相流输送管线和管路终端处理设备的设计及安全、经济运行的最重要依据 .由此可见 ,在两相输送过程中对液滴传输特性研究的重要性 .…     

超声波焊接条件对PC/ABS与PMMA焊接强度的影响

研究了聚碳酸酯(PC)/丙烯腈–丁二烯–苯乙烯塑料(ABS)合金超声波焊接材料设计及焊接条件,对其与聚甲基丙烯酸甲酯(PMMA)焊接强度的影响。研究发现,减少PC含量,采用高分子量的PC,都会使PC/ABS与PMMA超声波焊接的结合强度增加。可调节的几种焊接因素中,焊接时间和振幅对结合强度影响大,合适的加工参数才能得到焊接表面良好且焊接拉拔力大的焊接效果。工艺参数调制振幅70%,延长时间为0.7 s,焊接时间为0.2 s,保压时间为0.15 s,所得的焊接强度优异,表面效果较好。     

Sm(Co_(bal)Ni_(0.18)Fe_(0.1)Zr_(0.04))_x的永磁薄膜性能的研究

稀土永磁合金薄膜在微机电系统(MEMS)、磁记录介质、自旋电子元件和医疗科学领域有着重要的应用。Sm Co基永磁薄膜,其内禀居里温度高于其他永磁薄膜,高温条件下有更高的稳定性,因而在MEMS中具有潜在的应用前景。采用复合靶和纯钐靶共溅射制备出Sm Co基永磁薄膜样品,研究了薄膜合金中Sm含量以及退火温度等对Sm(CobalNi0.18Fe0.1Zr0.04)x相结构、微观形貌以及磁性能的影响,得出以下结论:退火温度对薄膜织构也有明显影响。随着退火温度提高,薄膜织构增强,矫顽力提高。随着Sm含量的提高,薄膜中Sm Co相析出增多,组织更加均匀,矫顽力明显提高。     

一种用于计算机辅助产物设计中基于BP-NN优化问题的求解方法

Because of the powerful mapping ability, back propagation neural network (BP-NN) has been employed in computer-aided product design (CAPD) to establish the property prediction model. The backward problem in CAPD is to search for the appropriate structure or composition of the product with desired property, which is an optimization problem. In this paper, a global optimization method of using the a BB algorithm to solve the backward problem is presented. In particular, a convex lower bounding function is constructed for the objective function formulated with BP-NN model, and the calculation of the key parameter a is implemented by recurring to the interval Hessian matrix of the objective function. Two case studies involving the design of dopamine β-hydroxylase (DβH) inhibitors and linear low density polyethylene (LLDPE) nano composites are investigated using the proposed method.     

CRITICAL SELF-ASSEMBLY CONCENTRATION OF AN IONIC-COMPLEMENTARY PEPTIDE EAK16-I

Understanding the process of self-assembly of peptides has been important in various biomedical engineering applications. This work focuses on the effect of peptide concentration on the molecular self-assembly of an ionic-complementary peptide, EAK16-I (AEAKAEAKAEAKAEAK), in aqueous solution. The surface tension and self-assembled nanostructures were determined for a wide range of peptide concentrations using axisymmetric drop shape analysis-profile (ADSA-P) and atomic force microscopy (AFM), respectively. Surface tension measurements revealed a critical self-assembly concentration of 0.3 mg peptide/ml water, below which the surface tension decreased rapidly with increasing peptide concentration, and above which the surface tension remained at a constant, plateau value. There were two structural transitions observed with increasing peptide concentration: the first was from globular nanostructures to fibrils, and the second from the fibrils to relatively thick fibers. The second structural transition occurred at the critical self-assembly concentration as determined by the surface tension measurements. The nanostructural behavior of EAK16-I was compared with that of EAK16-II, which has the same amino acid composition but a different charge distribution. Salt effects were also examined by adding NaCl to the peptide solution. The salt addition facilitated the formation of peptide fibrils at low peptide concentrations but increased the critical self-assembly concentration, which occurred at 0.8 mg peptide/ml water in the presence of 20 mM NaCl. The structural transitions involved in the self-assembly of EAK16-I resemble those from protofibrils to fibrils observed with numerous naturally occurring peptides. An understanding of this structural transition may have relevance in the analysis and treatment of peptide/protein conformational diseases and have application in the production of self-assembled protein nanostructures.     

预应力FRP在结构应用中的技术问题探讨

本文提出了预应力纤维聚合材料在结构应用中涉及的几个技术问题,如粘结锚固、张拉应力的大小及施工工艺的选取等,通过分析比较,并结合国内外在这些方面的研究成果,得出了一些结论和建议,为今后的研究与设计提供依据.     

不同曳力模型对鼓泡床内气固两相流的模拟研究

基于双流体模型,应用Fluent商业软件包对带有单喷嘴的二维鼓泡床中气固两相流进行模拟研究。采用三种基于不同机理的曳力模型;半经验的Gidaspow模型、由格子波尔兹曼方法导出的Koch-Hill模型与修正的半经验的McKeen模型,通过模拟气泡的形成、上升及破裂过程,气泡形状和颗粒运动特征,计算气体泄漏率、气泡直径及气泡上升速度,对不同曳力模型进行比较研究,其中编程实现了Koch-Hill和McKeen曳力模型模块。通过与文献中的实验结果进行对比发现,Gidaspow模型对气泡形状的模拟效果较好,与实验数据的误差介于其他两种模型之间;Koch-Hill模型捕捉到的气泡特征最逼真,且床层膨胀效果明显,但定量计算的误差最大;而McKeen模型与实验数据的误差最小,但对气泡形状的模拟效果较差。     

数控机床零点漂移的研究

通过对半闭环与全闭环系统数控机床回零原理的分析,阐述机床零点漂移产生的原因,以及对机床零点漂移的一些关键性解决办法。