Separation of Proteins via pH Parametric Pumping

Abstract

An equilibrium theory is used to study pH parametric pumps. Simple graphical procedures for predicting the separation are presented. It is shown that a parapump with a series of columns packed alternately with cation and anion exchangers is capable of yielding very high separation factors. Experimental results are in qualitative agreement with theory.     

Theory of Isotope Separation by Electrochemical Parametric Pumping

Abstract

Electrochemical parametric pumping is a novel separation process in which cycles of reversible electrochemical processes on high surface area electrodes are conducted in synchronization with cycles of solution flow through the separating column. In the present work, isotope separation by electrochemical parametric pumping is studied theoretically. The proposed model is based on the similarity between the parametric pumping and the countercurrent processes and on the division of the separating column to “cells” when dispersion processes are neglected. Steady-state isotopic concentration gradients are calculated and process optimization is performed with respect to system parameters such as the fraction of the isotopes bound to the electrode, the solution displacement volume, and the fraction of the isotopes withdrawn as product. The model may also be applicable to other types of parametric pumping.     

Stagewise Liquid-Liquid Extraction Parametric Pumping. Equilibrium Analysis and Experiments

Abstract

A staged contacting device adapted from Craig's countercurrent extractor has been designed to allow back and forth stepwise displacement of the light liquid phase while the heavy liquid phase remains stationary. Thermal parametric pumping experiments were run in this staged apparatus, at total reflux, with water as the heavy, stationary phase, toluene as the light moving phase, and phenol as the solute distributed linearly between the two phases. The transient and steady regimes of this operation are investigated by introducing a matrix formalism and studying the properties of eigenvalues and eigenvectors. It is shown how this formalism can be extended to more complex situations involving nonideal separations and transfer of phases, several transfers per half-cycle, and partial reflux.     

Manufacture of Porous Cross-Linked HEMA Spheres for Size Exclusion Packing Material

2-Hydroxyethyl methacrylate (HEMA), methyl methacrylate (MMA) monomers and ethyleneglycol dimethacrylate (EDMA) as a cross-linker, were reacted with the initiator 2,2,azobis-2-methylpropionitrile (AIBN) in the presence of dodecanol. The effect of increasing concentrations of dodecanol, as a porogen agent, was evaluated. The radical polymerization was carried out using an in situ prepared Mg(OH)₂ gel, at 70°C for 5 h. Following polymerization, the suspension was eliminated by neutralization for recovery of beads. The spherical particles obtained were filtered, washed with methanol using simple extraction and using a Soxhlet thimble, and dried at 60°C under vacuum. Scanning Electron Microscopy (SEM) revealed regularly shaped spherical beads containing macropores. Nitrogen Sorption Analysis (NSA) and Mercury Intrusion Porosimetry (MIP) were performed for evaluation of surface area, pore size and pore volume.     

The Bottlenecks of Preparing Virus Particles by Size Exclusion for Antibody Generation

Enterovirus 71 (EV71) is the major etiological agent contributing to the development of hand-foot-mouth disease (HFMD). There are not any global available vaccines or antibody drugs against EV71 released yet. In this study, we perform the virus immunization in a cost-effective and convenient approach by preparing virus particles from size exclusion and immunization of chicken. Polyclonal yolk-immunoglobulin (IgY) was simply purified from egg yolk and monoclonal single-chain variable fragments (scFv) were selected via phage display technology with two scFv libraries containing 6.0 × 10⁶ and 1.3 × 10⁷ transformants. Specific clones were enriched after 5 rounds of bio-panning and four identical genes were classified after the sequence analysis. Moreover, the higher mutation rates were revealed in the CDR regions, especially in the CDR3. IgY showed specific binding activities to both EV71-infected and Coxsackievirus 16-infected cell lysates and high infectivity inhibitory activity of EV71. However, while IgY detected a 37 kDa protein, the selected scFv seemingly detected higher size proteins which could be cell protein instead of EV71 proteins. Despite the highly effective chicken antibody generation, the purity of virus particles prepared by size exclusion is the limitation of this study, and further characterization should be carried out rigorously.     

Polysaccharide Characterization by Aqueous Size Exclusion Chromatography and Low-Angle Laser Light Scattering

Abstract

Aqueous size exclusion chromatography coupled with on-line low-angle laser light scattering (SEC/LALLS) is a valuable analytical tool for characterization of polysaccharides and other important biopolymers. This work reviews the fundamental size separation mechanism of polymers chromatographed via SEC, the development of SEC/LALLS methods for characterization of eluted polymers, and applications of this technique to determine polysaccharide physical and chemical properties. Important nonsize exclusion effects encountered in aqueous SEC of polysaccharides are discussed and attributed to intramolecular and polymer-support interactions, as well as flow-related anomalies. The necessity of absolute molecular weight detection as a direct means of calibration is presented. Low-angle laser light scattering coupled to SEC provides a simple method of direct calibration and allows determination of polymer molecular weight and molecular weight distribution. Recent applications of SEC/LALLS to determine polysaccharide branching characteristics are detailed. The combined knowledge of molecular weight distributions and branching distributions provides insight into the molecular kinetic events of polysaccharide processing operations.     

制动胶管编织骨架层的参数化建模

介绍制动胶管编织骨架层(简称编织层)参数化建模的方法。以规则编织层为例,基于Abaqus软件,采用Python脚本语言编写内核和图形用户界面代码,实现编织层参数化建模。该程序不仅具有编织层三维建模功能,还具有纤维相互作用设置、边界条件施加、网格划分和任务提交等功能,有效地简化了编织层力学性能分析,缩短了研究周期。     

High Performance Size Exclusion Chromatography of Polar Compounds in Heated and Non-Heated Fats

In this paper, separation of the polar compounds previously obtained from heated fats by column chromatography is proposed in order to increase knowledge of the alteration of frying fats. The analysis is carried out in 35 min by high performance size exclusion chromatography (HPSEC). The results demonstrate that the contribution of thermoxidative and hydrolytic degradations can be quantified. The method can also be applied to a better definition of non-heated fats.     

流线型挤出模参数化建模方法研究

在编程实现对型材截面轮廓凸凹性自动判断的基础上，采用射线法与比例间隔法相结合的方法，确定流道人口圆周上型值点的位置，以三次多项式作为流道模腔型曲线的数学模型，依据流线型要求给出的初始、边界条件得出型曲线的数学方程，构建了挤出模流道的三维参数化模型，为挤出模CAD／CAE的双向集成技术研究奠定基础。数值分析结果显示，该方法创建的流线型流道模型，其流动稳定性和平顺性都优于直线型流道。     

基于参数化设计的轮胎自动化建模研究

研究基于参数化设计的轮胎自动化建模。通过数据管理、数据重用、知识融合理论对轮胎特征进行标准化分类,再通过树状数据结构同步各子部件数据,将轮胎各子部件三维建模方法通过产品知识规则的形式融入三维软件的二次开发过程,实现轮胎子部件的自动化建模,从而同步到轮胎总装配部件,实现轮胎自动化建模。     

航空子午线轮胎几何参数化建模方法开发

针对1270×455 R22型航空子午线轮胎结构,提出一种几何参数化的建模方法。该方法使用参数39个（描述轮胎几何信息的参数16个,调整轮胎几何轮廓的参数23个）,通过建立截面外轮廓,钢丝圈、三角胶和胎体帘布层的轮廓,带束层、增强层与胎面的轮廓和帘线设计,可以精确建立航空子午线轮胎二维截面的几何模型。该方法可以加速轮胎结构的建模。     

Dynamic Modeling and a Parametric Study of an Indirect Solar Cabinet Dryer

A dynamic mathematical model for drying of agricultural products in an indirect cabinet solar dryer is presented. This model describes the heat and mass transfer in the drying chamber and also considers the heat transfer and temperature distribution in a solar collector under transient conditions. For this purpose, using conservation laws of heat and mass transfer and considering the physical phenomena occurring in a solar dryer, the governing equations are derived and solved numerically. The model solution provides an effective tool to study the variation of temperature and humidity of the drying air, drying material temperature, and its moisture content on each tray. The predicted results are compared with available experimental data. It is shown that the model can predict the performance of the cabinet solar dryer in unsteady-state operating conditions well. Furthermore, the effect of some operating parameters on the performance and efficiency of dryer is investigated and compared with selected published data.     

基于Pro/E注射机螺杆的参数化建模

以塑料注射机螺杆为例,介绍用Pro/E作为工具进行参数化设计的方法,详细介绍了采用Pro/E工具中的关系和参数命令对注塑机3种类型螺杆进行参数化建模的方法和不变参数的设定.利用参数界面改变参数可以自动生成螺杆的三维模型.通过进一步举例说明这一方法可以在已设定好参数的情况下建成不同规格注射螺杆,为螺杆设计节省时间.     

Intravesicular Genomic DNA Enriched by Size Exclusion Chromatography Can Enhance Lung Cancer Oncogene Mutation Detection Sensitivity

Extracellular vesicles (EVs) are cell-derived structures surrounded by a lipid bilayer that carry RNA and DNA as potential templates for molecular diagnostics, e.g., in cancer genotyping. While it has been established that DNA templates appear on the outside of EVs, no consensus exists on which nucleic acid species inside small EVs (<200 nm, sEVs) are sufficiently abundant and accessible for developing genotyping protocols. We investigated this by extracting total intravesicular nucleic acid content from sEVs isolated from the conditioned cell medium of the human NCI-H1975 cell line containing the epidermal growth factor (EGFR) gene mutation T790M as a model system for non-small cell lung cancer. We observed that mainly short genomic DNA (<35–100 bp) present in the sEVs served as a template. Using qEV size exclusion chromatography (SEC), significantly lower yield and higher purity of isolated sEV fractions were obtained as compared to exoEasy membrane affinity purification and ultracentrifugation. Nevertheless, we detected the EGFR T790M mutation in the sEVs’ lumen with similar sensitivity using digital PCR. When applying SEC-based sEV separation prior to cell-free DNA extraction on spiked human plasma samples, we found significantly higher mutant allele frequencies as compared to standard cell-free DNA extraction, which in part was due to co-purification of circulating tumor DNA. We conclude that intravesicular genomic DNA can be exploited next to ctDNA to enhance EGFR T790M mutation detection sensitivity by adding a fast and easy-to-use sEV separation method, such as SEC, upstream of standard clinical cell-free DNA workflows.     

Modeling of the Mixing of Disperse Materials Differing in Particle Size

A multistage mechanism is suggested for particle exchange in the preparation of multicomponent mixtures, and the layered model of mixing is adapted to the case of particles differing in size and/or density.     

Modeling of Chemical Vapor Infiltration Rate Considering a Pore Size Distribution

To analyze chemical vapor infiltration (CVI) rates, a simulation model (PC model) was proposed, which is capable of considering difficulties of densification in the internal regions of porous bodies and the pore closure phenomena. In the model, a fictitious tapered pore is constructed based on the pore size distribution of the preform body, and variation of the pore shape during the process is calculated. For simulation study, fictitious tapered pores were constructed using different pore size distribution functions of Gaussian, δ-function, and flat distribution, and their shapes and characteristics were compared. In the case of the Gaussian flat distribution (large dispersion), the fraction of fine pores was large and these pores became closed near their mouths. Reconversion of temporal fictitious pore shape into the pore distribution function was attempted and the PC model was successfully applied to monitor variations in the pore size distributions during the CVI process.     

Experimental Determination and Modeling of Bubble Size Distributions in Bubble Columns

Using a five point conductivity technique local values of bubble size,bubble velocity and gas fractionhave been experimentally determined in a 288 mmID and 4.3 m high bubble column as a function of axial andradial position for the air/water and CO_2/N_2/aqueous MDEA systems.The experimental results are comparedwith predictions from a fundamental two-fluid model.The implementation of a non-steady lateral drag term inthe two-fluid model has been shown.In addition to improving the physical realism of the model,it is found togive slight improvements in the predictions of the distributions of local bubble size.Predictions of bubble size arefound in reasonable agreement with experimental values in the heterogeous flow regime,whereas they are stil1found to be unreliable at low gas velocities.Local void predictions are found in reasonable agreement with experi-mental values,but deviations occur in the homogeneous flow regime towards the wall.This is attributed to defi-ciencies in the simplified bubble size mode