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Physical and Dielectric Properties of Some Nonionic Surfactants

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Journal of Materials Science & Technology 1998年第4期14卷 361-367页

作者： El-Anwar, I.M. El-Henawii, S.A. National Research Center Dokki Cairo Egypt Faculty of Science Helwan University Egypt

Fatty acid esters have been prepared by reacting the acid C//1//8 with polyethylene glycols having varying numbers of oxyethylene units (4-88 units) by the direct esterification reaction method. surface and interfacial tensions were studied at various experimental conditions, including, concentration, temperature and chemical constitution of the surfactant. Critical micelle concentrations (CMC), surface excess and residual area occupied by each surface active agent molecule A have been calculated by using Gibb's equations. CMC values range from 10 to 55 multiplied by 10** minus **5 mole/L for all studied agents, while the residual area occupied by each molecule varies from 0.6 to 1.5 nm**2. Variation of CMC of some of these agents with temperature have been also examined and the obtained data were used to calculate the heat of micellization delta H//m and the entropy change during micellization delta S//m. Values of delta H//m vary from 14.63 kJ/mole to 2.717 kJ/mole depending on the chemical constitution of the agent under consideration. The apparent dipole moments mu of three surfactant were measured following the Headstrand's method. (Edited author abstract) 23 Refs.

关键词： surface active agents

Effects of Concentration and Conformation of Surfactants on Phase Separation of Surfactant-Water-Oil Systems

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Chinese Physics Letters 2004年第4期21卷 709-712页

作者：袁银权邹宪武刘昊阳 DepartmentofPhysics WuhanUniversityWuhan430072

The effects of surfactants on the phase separation of surfactant–water–oil systems have been investigated by using discontinuous molecular dynamic simulations. The phase separation speed and equilibrium configuration are dependent on the surfactant concentration and conformation. The equilibrium concentration of surfactants at the interface remains constant. With the increasing surfactant concentration, the equilibrium configuration crosses over from the disperse phase to the bicontinuous one. The crossover concentration is estimated. The conformation of the surfactant has little effect on the equilibrium concentration of surfactants at the interface, while it affects the equilibrium configuration after phase separation.

关键词： surface active agents

Nucleation Behaviour in the Initial Stage of Surfactant-Mediated Epitaxial Growth

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Chinese Physics Letters 2004年第10期21卷 2029-2032页

作者：王戴木孙霞丁泽军吴自勤 StructureResearchLaboratoryandDepartmentofPhysics UniversityofScienceandTechnologyofChinaHefei230026 DepartmentofAstronomyandAppliedPhysics UniversityofScienceandTechnologyofChinaHefei230026

The nucleation kinetics in the early stage of epitaxial growth mediated by a monolayer of surfactant is studied by using kinetic Monte Carlo simulations. Our simulation model includes three main kinetic parameters: a small barrier for adatom diffusion on the surfactant terrace, a higher barrier for the exchange of adatoms with their underneath surfactant atoms, and a highest barrier for the recovery exchange in which an exchanged adatom resurfaces to the top of the surfactant layer. The simulations reveal a distinct transition of nucleation behaviour as the different atomic processes are activated successively with increasing temperature. The total nucleus density as a function of temperature exhibits a complex N-shape with a minimum and a maximum, which define the transition temperatures. The characteristic behaviour of nucleation density is helpful to rationalize the experimental observations on the temperature dependence of growth mode in some surfactant-mediated epitaxial systems.

关键词： surface active agents

Extraction of copper ions by supercritical carbon dioxide

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Journal of Environmental Sciences 2000年第4期12卷 444-447页

作者： Cui, Z. Liu, J. Gao, L. Wei, Y. Dept. of Environmental Engineering Shandong University Jinan 250100 China

Complexation combined with supercritical fluid extraction was used to extract Cu2+ in this study. The effects of pressure, temperature, volume of CO2 on the efficiency of extraction were systematically investigated. At the optimum condition a 57.32% recovery was achieved. Addition of suitable amount of methanol (v/v = 5%) to the supercritical CO2 can increase in the extraction of Cu2+ (72.69%, RSD = 2.12%, n = 3). And the recovery can further increase in the presence of non-ionic surfactant Triton X-100 because of its function of solubilization. Surfactant was first used in the extraction of metal ions in the present study, and the results are satisfied (90.52%, RSD = 2.20%, n = 3).

关键词： Carbon dioxide Chelation Copper Methanol Positive ions Pressure effects Solubility surface active agents Thermal effects

Agglomeration Control of Ultrafine Y_2O_3-ZrO_2 and (MgO, Y_2O_3)-ZrO_2 Powders Synthesized by Coprecipitation Process

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Transactions of Tianjin University 2005年第1期11卷 17-21页

作者：马亚鲁张宇郑俊萍 School of Sciences Tianjin University Tianjin 300072 China School of Materials Science and Technology Tianjin University Tianjin 300072 China

Chemical coprecipitation was used to produce ultrafine and easily sinterable Y2O3-stabilized and （Y2O3,MgO）-stabilized ZrO2 powders. Six precipitation processes for preparation of ZrO2-based ultrafine powders were designed separately, meanwhile different techniques used to control the agglomeration formation were proposed. By means of TEM, SEM, Raman spectroscopy and IR spectroscopy, the mechanisms of agglomeration control in the precipitation processes and post-precipitation and drying process were investigated. The experimental results show that adding appropriate anion surface active agents （such as PAA1460） or polymer （PEG1540 matching with PEG200） in aqueous solution systems during precipitation processes could reinforce charge effect and location effect for gel particles interface. Adding wetting agents to wet gels washing with distilled water during drying process could change interface structure of gel particles and decrease surface tension between gel particles. The agglomeration control in the precipitation, post-precipitation and drying processes had remarkable influence on the characteristics of powders. By adding various macromolecules in the processes, the agglomeration state could be controlled efficiently, and the characteristics of powders were improved.

关键词： coprecipitation Y_2O_3-stabilized ZrO_2 powders (MgO,Y_2O_3)-stabilized ZrO_2 powders agglomeration control surface active agents

The development of the region between the preexisting and nascent membranes during the first cleavage of Rana amurensis eggs

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Cell Research 1991年第1期 35-43页

作者： GAO QIRONG, KONGHUA ZHANG, LONGSHENG HONG,CHENGTANG XU AND GUOYAN GU (formerly KUOYENKU)Shanghai Institute of Cell Biology, Academia Sinica

The region between the preexisting and nascentmembranes of a cleaving Rana egg is a dense protrusionregion of nearly 40μm wide at 180°***,thisregion differentiate,into an upper part,a strip withlong, branched and randomly distributed protrusionswhich are derived largely from the preexistingmembrane,and a lower part,a band with *** 4-and 8-cel1 stages,the strip is almost vanishedand microvilli in the band is *** nascentmembrane is smooth at the 180°stage,then a rough areaappears below the smooth region and quickly *** germ agglutinin which can bind to preexistingmembrane interrupts the development of the regionbetween the preexisting and nascent ***,Brij,having the property to increase the areaof nascent membrane,does not interrupt the developmentof the region between the preexisting and nascentmembranes.

关键词： Gleavaqe region between the preexisting and nascent membranes surface active agents wheat germ agglutinin Rana amurensis eggs.

Structure and photoluminescence properties of fishbone-like PbMoO_4 nanostructures obtained via the surfactant-assisted hydrothermal method

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Chinese Optics Letters 2012年第11期10卷 65-68页

作者：贾润萍郑康生 School of Materials Science and Engineering Shanghai Institute of Technology

Fishbone-like PbMoO4 nanostructures are successfully obtained via the surfactant-assisted hydrothermal method at 160 ℃. Polyethylene glycol （PEG2000） is used as the template agent. The nanostructures are characterized via X-ray diffraction, field-emission scanning electron microscopy, Fourier transform infrared spectroscopy, ultraviolet-visible light （UV-Vis） spectroscopy, and photoluminescence （PL） measurements. The PbMoO4 morphology is highly associated with the molecular nature of PEG2000. PbMoO4 nanoparticles obtained from PEG2000 have a fishbone-shaped, scheelite-type tetragonal structure, in which numerous secondary branches vertically grow on both sides of the main stem. The structures exhibit broad PL emission bands with the maximum at 306 and 390 nm when excited at 250 nm. In addition, the UV-Vis absorption edge of the structures is in the 280 to 310 nm region, and the band gap is 4.07 eV. A plausible formation mechanism for the fishbone-like PbMoO4 nanostructures is also discussed.

关键词： Fourier transform infrared spectroscopy Photoluminescence Polyethylene glycols surface active agents Tungstate minerals X ray diffraction