Shapes of lipid monolayer domains: Solutions using elliptic functions

Solid lipid monolayer domains surrounded by a fluid phase at an air-water interface exhibit complex shapes. These intriguing shapes can be understood in terms of a competition between line tension and long-range dipole-dipole interaction. The dipolar energy has recently been relevant to a negative line tension and a positive curvature energy at the boundary, and a corresponding shape equation was derived by the variation of the approximated domain energy (Phys. Rev. Lett. 93, 206101 (2004)). Here we further incorporate surface pressure into the shape equation and show that the equation can be analytically solved: the curvature of the domain boundary is exactly obtained as an elliptic function of arc-length. We find that a circular domain can grow into bean-and peach-like domains with pressure, i.e., dipping and cuspidal transitions of circle by compression. The comparison with the experimental observation shows nice agreement.     

Determination of arsenic(III) and total inorganic arsenic in water samples using an on-line sequential insertion system and hydride generation atomic absorption spectrometry

A simple and robust on-line sequential insertion system coupled with hydride generation atomic absorption spectrometry (HG-AAS) was developed, for selective As(III) and total inorganic arsenic determination without pre-reduction step. The proposed manifold, which is employing an integrated reaction chamber/gas-liquid separator (RC-GLS), is characterized by the ability of the successful managing of variable sample volumes (up to 25 ml), in order to achieve high sensitivity. Arsine is able to be selectively generated either from inorganic As(III) or from total arsenic, using different concentrations of HCl and NaBH₄ solutions. For 8 ml sample volume consumption, the sampling frequency is 40 h⁻¹. The detection limit is c_L = 0.1 and 0.06 μg l⁻¹ for As(III) and total arsenic, respectively. The precision (relative standard deviation) at 2.0 μg l⁻¹ (n = 10) level is s_r = 2.9 and 3.1% for As(III) and total arsenic, respectively. The performance of the proposed method was evaluated by analyzing the certified reference material NIST CRM 1643d and spiked water samples with various concentration ratios of As(III) to As(V). The method was applied for arsenic speciation in natural waters samples.     

The application of chromatography to the analysis of pharmaceutical creams

Summary The application of GLC, HPLC and TLC to the analysis of pharmaceutical creams is discussed with special attention to sample clean-up. The results of the determination of hydrocortisone acetate, salicylic acid, benzoic acid, diethyl stilbestrol, chloramphenicol, diphenhydramine HCl, tretinoin and some cream base components by reversed phase HPLC are given.Presented at the 14th International Symposium on Chromatography London, September, 1982     

Study of gas-liquid partitioning of alkane solutes in several organic solvents by using principal component analysis and linear solvation energy relationships

Principal component analysis (PCA) was used to extract the number of factors which can describe the 737 gas-liquid partition coefficients of five linear, four branched, and two cyclic alkanes in 67 common solvents. Based on the reconstruction of partition coefficient data matrix, we concluded that the experimental dataset could readily be reduced to two relevant factors. Using only these two factors, there were no errors larger than 3%, 7 cases had errors larger than 2%, and in 34 cases, errors were between 1 and 2%. n-Hexane and ethylcyclohexane were chosen as the test factors, and all other partition coefficients were expressed in terms of these two test factors. Prediction of the logarithmic partition coefficient of these alkanes in seven chemically different solvents, which were originally excluded from the data matrix, was excellent: the root mean square error was 0.064, only in 11 cases the errors were larger than 1%, and only 3 had errors larger than 4%.Linear solvation energy relationships (LSERs) using both theoretical and empirical solvent parameters were used to explain the molecular interactions responsible for partition. Several combinations of parameters were tried but the standard deviations were not less than 0.31. This could be attributed to the model itself, imprecisions in the data matrix or in some of the LSER parameters. Solvent cohesive parameters and surface tension in combination with polarity-polarizability or dispersion parameters perform the best.Finally, the two principal component factors were rotated onto the most relevant physicochemical parameters that control the gas-liquid partitioning phenomena.     

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在自行设计与建造的液态锂铅合金鼓泡器实验系统上,开展了气-液接触法提取液态锂铅合金中的氢。实验结果表明,氦气比氩气更适合作填料塔的载带气;塔温越高,塔出口端氢含量越大;载气流速对出口端氢含量的影响呈锯齿状,无明显规律。实验结果虽然与文献数据有差别,但可以认为采用气-液接触法提取液态锂铅中的氢同位素是可行的,提取效率是随液态锂铅在填料塔中滞留的时间增长而增大的。     

旋流式气液分离器内流场的数值模拟

气液分离器作为制冷系统中的关键部件,其分离性能的优劣对系统有着重要的影响。为了研究旋流式气液分离器的分离性能,首先从理论上介绍了旋流式气液分离器的分离机理,列出其主要结构参数,然后基于计算流体动力学(CFD)方法,采用Gambit建模,利用Fluent软件,对旋流式气液分离器进行了模拟仿真,并对进口附近壁面速度场、不同尺寸和进出口截面流场矢量图、纵向剖面气液体积分数分布图等进行了重点分析。仿真结果表明设计是正确、合理的。     

聚变堆液态包层提氚鼓泡器的概念设计

在气-液接触法提取液态锂合金中的氢的实验基础上,提出了以气-液交换柱为核心的提氚鼓泡器(LBTB)的概念设计。LBTB 主要由气体进样纯化器、气-液交换柱系统、饱和器－解吸器和辅助系统构成。LBTB以氩氢混合气为吹洗气,其主要功能是在线监测液态包层主回路中的氚行为,并检验多柱级联后的氚回收率是否可以达到90%的期望值。     

Topological causality analysis of horizontal gas-liquid flows based on cross map of phase spaces

Nonlinear systems are always characterized by the interactions between constituents which yield data in the form of time series. Exploration of the causality between the times series is beneficial for understanding the dynamics of the system. We introduce a topological causality method to explore the dynamics of horizontal gas-liquid flows. First, the principle of the topological causality algorithm is illustrated and validated using the Lorenz system and transfer entropy. Then, we conducted an experiment of gas-liquid flows in a horizontal pipe, during which a wire-mesh sensor (WMS) was used to capture the flow structures. The WMS data at different time frames are embedded in high-dimension phase spaces. Through building a cross map between coupled phase spaces, a cross map smoothness was employed to derive the topological causality index. The causality index enables us to understand the mechanism of the flow pattern transition and the intrinsic dynamics of the transient gas-liquid flows.     

气液两相流中的声速研究

气液两相流在工业各领域中广泛存在,而声速是描述其声学性质的一个重要参数。本文从流体的体积弹性模量的定义出发,推导了气液两相流中的声速随含气率的变化关系式,即混合流体的Wood声速公式,将其声速的部分计算结果和其他作者的实验数据进行了比较,吻合良好。并通过COMSOL有限元模拟软件得到不同气体分布下圆管谐振腔最低阶模式的共振频率,间接数值模拟研究了含气率对声速的影响。模拟结果与理论计算结果一致,当气液两相流中含气率较低时,声速随含气率的增大急剧减小。本研究结果为确定声速与气液两相流中的含气率间的关系提供了参考依据。     

Gas-Liquid Chromatographic Analysis of Mixtures of Cis- and Trans-Crotyl Alcohol in Commercial Samples and in the Products of Controlled Potential Electrolysis of Crotonaldehyde

Abstract

G. L. C. enabled a separation of cis- and trans-crotyl alcohol. Commercially available samples of crotyl alcohol and the products of controlled potential electrolysis of crotonaldehyde contained about 20% of the cis-form. The limited amount of information available on N. M. R. spectra of similar compounds prevented an application of the coupling constants for the interaction between a methyl group and ethylenic protons in attribution of the trans-structure. Attribution of trans-structure to the predominant form was based upon I. R. spectra and synthesis of the trans-isomer.