Spontaneous Vesicle Formation in Aqueous Mixtures of Cationic Surfactants and Partially Hydrolyzed Polyacrylamide

Spontaneous vesicle formation was observed in aqueous mixtures of partially hydrolyzed polyacrylamide and single-tailed cationic surfactants. The influences of pH, addition of long-chain alcohols, variation of hydrocarbon chain length, and head group size of the cationic surfactants were investigated systematically. It was found that 30-50% hydrolyzed degree of polyacrylamide and cationic surfactants with 10 or 12 methylene groups are suitable for vesicle formation in the mixed aqueous systems at pH 9.2. Addition of long-chain alcohols was found to be helpful for vesicle formation in some cases. The vesicle stability was also investigated at various temperatures and amounts of ethanol addition. Copyright 2001 Academic Press.     

Organic Chemistry Without Solvent. Improvements to the One Step Preparation of Dibenzyl Sulphones

Dibenzyl sulphones can be prepared from the corresponding benzyl halide under mild, economic and efficient conditions, using either sodium dithionite / Aliquat, or sodium formaldehyde sulphoxylate /potassium carbonate in the absence of solvent.     

Isotope effects on the microphase separation of paraffin mixtures

Isotopic sensitivity is reported in both the formation and the above ambient temperature annealing behaviour of lamellar microphases in C₃₀:C₃₆ paraffin solid solutions. The time resolved small angle neutron scattering from a 1:1 C₃₀H₆₂:C₃₆D₇₄ mixture and its complementary pair 1:1 C D :C H has been studied. Upon quenching such mixtures from the melt; the solid solution so formed nucleates spontaneously to a ‘long period’ microphase. The two systems differ in that for 1:1 C₃₀D₆₂:C₃₆H₇₄ there is also strong diffraction at Q = 0·136 A^-1 associated with C₃₆H₇₄ enrichment of the solid solution or a separate phase. Both processes are sensitive to the isotopic composition of the mixture. For both systems the long period scattering from a quenched liquid mixture develops in periods of hours at ambient temperature. Heating the aged microphase structures to temperatures above about 43°C causes them to disappear, but again isotropic sensitivity is noted. It is concluded that the effects are largely kinetic in origin, in agreement with earlier IR studies on intralamellar microaggregation in this system.     

Dynamics of Lump Solutions in a 2 + 1 NLS Equation

We derive a class of localized solutions of a 2+1 nonlinear Schrödinger (NLS) equation and study their dynamical properties. The ensuing dynamics of these configurations is a superposition of a uniform, "center of mass" motion and a slower, individual motion; as a result, nontrivial scattering between humps may occur. Spectrally, these solutions correspond to the discrete spectrum of a certain associated operator, comprised of higher-order meromorphic eigenfunctions.     

实施环境管理体系,提高企业市场竞争力

重点介绍了企业实施ISO14001环境管理体系的必要性。     

ISO 14644-1洁净室空气洁净度等级标准的特点

对洁净室空气洁净度等级标准的国际标准ISO14644—1与美国标准FS209E的主要不同点进行列举并对IS014644—1在等级依据公式及表达格式方面的特点进行对比分析。     

介质阻挡放电与脉冲电晕放电净化气态污染物的试验研究

利用自行研制的介质阻挡及脉冲电晕放电低温等离子体发生器对空气中氨、硫化氢、甲苯等5种气态污染物进行净化，并探讨了两种放电方式的原理和特点。试验结果表明：与介质阻挡放电相比，脉冲电晕放电具有更好的净化效果。     

多管式低阻高效空气过滤器的阻力特性研究

介绍了一种多管式高效空气过滤器。在不同风量下对各种试验规格过滤器的阻力和过滤效率进行了实验测定，分析了过滤器结构形式对其阻力的影响，讨论了阻力的变化规律。结果表明：该过滤器具有阻力低、效率高的特点，是一种适应我国国情，节能、价廉、有实用价值的新型空气过滤设备。     

功能性空气过滤材料及其应用

论述了功能性空气过滤材料的各种功能及功能性作用机理，并介绍了几种功能性滤料的特性和应用，提出了功能性滤料的发展方向。