Evaluation of recombinant green fluorescent protein, under various culture conditions and purification with HiTrap hydrophobic interaction chromatography resins

To determine the influence of various culture conditions, transformed cells of Escherichia coli expressing recombinant green fluorescent protein (GFPuv) were grown in nine cultures with four variable conditions (storage of inoculated broth at 4°C prior to incubation, agitation speed, isopropyl-β-d-thiogalactopyranoside [IPTG] concentration, and induction time). The pelleted cells were resuspended in extraction buffer and subjected to the three-phase partitioning (TPP) extraction method. To determine the most appropriate purification resin, protein extracts were eluted through one of four types of HiTrap hydrophobic interaction chromatography (HIC) columns prepacked with methyl, butyl, octyl, or phenyl resins and analyzed further on a 12% sodium dodecylsulfatepolyacrylamidegel. With Coomassie staining, a single band between 27 (standard GFPuv) and 29 kDa (molecular weight standard) was visualized for every HIC column sample. TPP extraction with HIC elution provided about 90% of the GFPuv recovered and eight-fold GFPuv enrichment related to the specific mass. Rotary speed and IPTG concentration showed, respectively, greater negative and positive influences on GFPuv expression at the beginning of the logarithmic phase for the set culture conditions (37°C, 24-h incubation).     

On the three-phase mass transfer with solid particles adhered to the gas-liquid interface

A heterogeneous, multi-layer mass transfer model is proposed for prediction of the effect of multi-layer packing of catalyst particles adhered to the gas-liquid interface. The behavior of the mass transfer rate with respect to the multi-layer packing, to the particle size and mass transfer coefficient without particles is discussed. It is shown that enhancement can be considerably increased by multi-layer packing compared to that of mono-layer packing, depending on the values of particle size and mass transfer coefficient. The predicted mass transfer rates using the proposed model was verified with experimental data taken from the literature. The model presented should be superior to that of published in the literature.     

Some selected problems of nonaqueous microemulsions — phase diagrams and variation of the composition in the quaternary and ternary systems

A variety of quaternary and ternary systems of the type of dodecane/aliphatic alcohols/Na-dodecyl sulphate/water or a water-replacing component (formamide, ethylene glycol, propylene glycol, propylene carbonate, dimethylsulfoxide, acetonitrile) were subjected to a comparative analysis of microemulsification. The compositions of the systems of the type of oil/surfactant/cosurfactant/water or nonaqueous liquid were changed with respect to surfactant (Na-dodecyl sulfate and triton X 114) concentration, cosurfactant (homologous aliphatic alcohols) concentration and mixing ratio of water and water-replacing component. The appertaining phase diagrams were plotted and compared with those of aqueous systems.The experimental results suggest that the phase regions, which are designated as nonaqueous microemulsions, probably represent, not only microemulsions in the usual sense, but a separate kind of mixed phase whose microstructure is examined by special studies. Analogously to aqueous microemulsion systems, transparency and spontaneous formation of homogeneous multicomponent systems cannot serve as the sole criteria for waterless microemulsion formation. But they are important guiding properties of microemulsion formation in multicomponent systems.The variety of components involved in the chemical composition and the current insufficient knowledge do not permit to generally decide whether nonaqueous systems can be assigned to microemulsions or to molecular solutions. For clarifying this problem a detailed examination of the miscibility behavior, especially that of binary systems as a function of temperature, and the role that surfactant and cosurfactant play in the formation of homogeneous systems will be necessary.     

Thermodynamic behavior of adsorption systems with porous adsorbents along the curves describing equilibrium between bulk phases of an adsorptive

The thermodynamic aspects of adsorption equilibrium in systems with crystalline, liquid, and dense gas phases have been considered. The heats of phase transition and corresponding directions of mass transfer from the adsorbed phase into crystalline and liquid phases at different temperatures have been determined. The general equilibrium diagram in the coordinates Inp-T ^–1 has been given with indication of the equilibrium lines of three-phase systems and characteristic points on the isosteres of adsorption,viz., the Gurvitsch and quasicritical points.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1480–1485, August, 1995.     

三相流运动力学对减缓膜生物反应器膜污染的理论分析

运用气、液、固三相流运动力学原理对一体式膜生物反应器运行过程分析,得出:①反应器膜外污染的临界流速与膜管抽吸压力及主腔宽度、曝气条件的关系;②膜管内膜壁存在或不存在凝胶层条件下,产生污染的临界速度与膜管径、污染物粒径、膜管内抽吸压力、膜管内流态及膜壁对污染物吸附力的关系;③消除膜污染运行控制措施及条件.     

多层百页窗式挡板三相流化床中液体流动模型

在矩形气液固三相流化床反应器中,采用脉冲应答技术,考察了挡板结构、气液流量、固体浓度对床层液体混合行为的影响.分别用多釜串联模型与轴向扩散模型描述挡板下方区域与挡板段的液体混合行为,应用矩量法及根据实验数据回归,得到了表征液相返混程度的模型参数的经验关联式.     

基于虚拟仪器和神经网络的电力电子电路故障诊断

电力电子电路中晶闸管开路和短路故障最为常见，为实现故障的在线自动诊断，以三相整流电路为例，利用虚拟仪器进行数据采集、分析及特征信号提取，特征信号作为神经网络的输入进行电力电子电路在线故障诊断，通过实验验证，该方法误诊率极低，达到了较为理想的效果。     

一种新型矩阵式可控整流器的研究

基于三相-三相矩阵式电力变换器的拓扑与开关函数，建立了一种三相可控整流器的变换拓扑和开关函数矩阵，理论分析与仿真分析了该整流器的变换性能．结果表明该整流器具有宽范围输出电压调节能力、输入电流零位移和能量的双向流动等优点。     

The study of the stability of aqueous three-phase fire-resistant foam in typical liquidus hydrocarbons

The utilization of solid particles in aqueous foam has a great potential in improving fire fighting efficiency. In this study, aqueous foam supported by micro fly-ash (FA) was prepared and its stability in a specific type of oil was characterized. Firstly, different amount of FA was added to study the influence of FA concentration on foamability. It showed that within a specific extent, foam expansion ratio increased with the increasing of FA concentration. And compared with conventional foams, oil resistance of FA stabilized foams, which was investigated by analyzing drainage rate and evolution process with a self-made apparatus, was remarkably improved when FA concentration exceed 4.8wt.%. Secondly, SiO₂ and Al₂O₃ particles with different median sizes were used to study the effect of particle size on stability. However, the smaller hydrophilic particles didn’t behave better as expected. Moreover, the foam stability in three hydrocarbons was evaluated in the same way. The results indicated that the short chain hydrocarbons had much stronger detrimental effect to both two-phase foam and three-phase foam. But overall, the three-phase foam stabilized by FA exhibited much better oil resistance, so it can be used as a promising material for pool fire extinguishing and prevention.GRAPHICAL ABSTRACT     

Laguncularia racemosa Phenolics Profiling by Three-Phase Solvent System Step-Gradient Using High-Performance Countercurrent Chromatography with Off-Line Electrospray Mass-Spectrometry Detection

The detailed metabolite profiling of Laguncularia racemosa was accomplished by high-performance countercurrent chromatography (HPCCC) using the three-phase system n-hexane–tert-butyl methyl ether–acetonitrile–water 2:3:3:2 (v/v/v/v) in step-gradient elution mode. The gradient elution was adjusted to the chemical complexity of the L. racemosa ethyl acetate partition and strongly improved the polarity range of chromatography. The three-phase solvent system was chosen for the gradient to avoid equilibrium problems when changing mobile phase compositions encountered between the gradient steps. The tentative recognition of metabolites including the identification of novel ones was possible due to the off-line injection of fractions to electrospray ionization mass spectrometry (ESI-MS/MS) in the sequence of recovery. The off-line hyphenation profiling experiment of HPCCC and ESI-MS projected the preparative elution by selected single ion traces in the negative ionization mode. Co-elution effects were monitored and MS/MS fragmentation data of more than 100 substances were used for structural characterization and identification. The metabolite profile in the L. racemosa extract comprised flavonoids, hydrolysable tannins, condensed tannins and low molecular weight polyphenols.