Solubilization of unilamellar liposomes by betaine-type zwitterionic/anionic surfactant systems

The mechanisms governing the solubilizing interactions between zwitterionic/anionic mixed surfactant systems at different molar fractions of the zwitterionic surfactant (X_zwitter) and neutral or electrically charged unilamellar liposomes were investigated. The mixed systems were formed by N-dodecyl-N,N-dimethylbetaine and sodium dodecyl sulfate in the presence of piperazine-1,4-bis-(2-ethanesulfonic acid) buffer at pH 7.20. Unilamellar liposomes formed by egg phosphatidylcholine, in some cases together with stearylamine or phosphatidic acid, were used. Solubilization was detected as a decrease in static light-scattering of liposomes. Two parameters were regarded as corresponding to the effective surfactant/lipid molar ratios (Re) at which the surfactant system (i) saturated the liposomes, Re_sat, and (ii) led to a total solubilization of liposomes, Re_sol. From these parameters the bilayer/aqueous medium surfactant partition coefficients for the saturation (K_sat) and complete bilayer solubilization (K_sol) were determined. When X_zwitter was 0.40, The Re and K parameters showed a maximum, whereas the critical micellar concentration (CMC) of these systems exhibited a minimum, regardless of the electrical charge of bilayers. Given that the ability of the surfactant systems to saturate or solubilize liposomes is inversely related to the Re_sat and Re_sol parameters, these capacities appear to be directly correlated with the CMC of the mixed systems. The similarity of both K_sat and K_sol (particularly for X_zwitter=0.2–0.8) suggests that a similar partition equilibrium governs both the saturation and the complete solubilization of bilayers, the free surfactant concentration (S_a,S_b), remaining almost constant with similar values to the CMC for each mixed system studied.     

新设备新工艺在热镀锌机组上的应用

汽车工业是21世纪的支柱产业之一.随着中国加入WTO和世界经济一体化速度的加快,国内汽车市场成为国际竞争舞台,作为高级轿车外板主要原材料之一的热镀锌板以其良好的性价比越来越受到汽车行业的青睐.通过宝钢现有热镀锌机组与国外同类热镀锌机组的对比,简要介绍一些新设备、新工艺在现代热镀锌机组上的应用,主要包括前清洗、退火炉、镀锌段和平整段.     

The intervalley X6→Γ6, L6 scattering time in GaAs measured by ultrafast pump-probe infrared absorption spectroscopy

A direct measurement of the dynamics of electrons in the X₆ valley for a GaAs crystal by time-resolved absorption spectroscopy is reported for the first time. IR picosecond probe pulses were used to monitor the growth and decay of the population in the X₆ valley subsequent to excitation by a 527 nm pump pulse. The intervalley X₆→Γ₆, L₆ scattering time t_x of 0.70 ± 0.50 ps is determined and the crossection for the X₆→X₇ transition is estimated to be 1.8 × 10⁻¹⁶ cm².     

热宽带钢连轧机调宽轧制工艺参数研究

模拟宝钢２０５０ｍｍ热带钢连轧粗轧机组调宽轧制工艺，得到不同铸坯宽度压下效率、立辊轧制狗骨高度和宽度以及平轧轧制时宽展量等的变化规律。为制定合理的调宽轧制压下规程，Ｒ４机架轧后板坯实现最小切头、切尾损失，最大程度实现连铸坯宽度尺寸集约化提供了可靠的依据。     

GCK－Ⅱ光电测宽仪──用CCD改造引进的二手测宽仪

本文介绍了用电荷耦合器件（ＣＣＤ）改造引进的日本二手测宽仪，并已用于太钢热连轧生产现场，取得了良好的应用效果。     

美国热煤气脱硫吸附剂的发展现状

概述了美国几种较成熟的热煤气脱硫吸附剂的配方、制备技术及吸附剂在若干试验条件下强度、活性、寿命等宏观特性的测试结果。     

GCr15控制轧制新工艺的模拟研究

用热扭转试验机，实现了热变形模拟轴承钢控制轧制工艺。研究了形变过程中所发生的静态和动态软化过程，观察了形变后的组织，证实在生产过程中实现的可能性，为在生产中推广使用提供了科学依据。     

莱钢焦化厂精苯生产加热改造方案

莱钢焦化厂以导热油代替蒸汽用于精苯生产及导热油炉工艺，经合理设定各项操作参数，提高了精苯加工能力，解决了蒸汽压力不足影响精苯生产的难题．     

对梁,底组合步进式加热炉半热滑轨的改进实践

介绍了间断式半热滑轨的研制和应用过程，以及经过节能技术改造，用新型半热滑轨代替老式滑轨的使用。实践表明，不但解决了以往的水梁漏水的问题，而且使线Ｃ级品率提高了３．３９％，每年可增产３５００ｔ线材，吨钢热涌单耗降低０．１４ＧＪ，年创经济效益２３９万元。     

热连轧过程自动化控制系统的应用

介绍日照钢铁1580mm热轧带钢过程控制系统的应用,以及系统配置、网络结构、中间件和应用软件功能。