Spontaneous vesicle formation in aqueous mixtures of single-tailed surfactants

Spontaneous, single-walled, equilibrium vesicles can be prepared from aqueous mixtures of simple, commercially available, single-tailed cationic and anionic surfactants. Vesicle size, surface charge, or permeability can be readily adjusted by varying the ratio of anionic to cationic surfactant. Vesicle formation apparently results from the production of anion-cation surfactant pairs that then act as double-tailed zwitterionic surfactants. These vesicles are quite stable in comparison to conventional vesicles prepared by mechanical disruption of insoluble liquid crystalline dispersions.     

非离子型表面活性剂微乳的研制

以脂肪醇聚氧乙烯醚(AEO-7),聚乙二醇400单硬脂酸酯(PEG400MS),聚氧乙烯脂肪酸酯(LAE-9),蓖麻油聚氧乙烯醚-40(EL-40),蓖麻油聚氧乙烯醚-60(EL-60)和烷基糖苷(APG)等为表面活性剂,以甘油、丙二醇和1,3-丁二醇为助表面活性剂制备微乳液,通过绘制伪三元相图研究不同表面活性剂、助表面活性剂和油相等因素对微乳形成区大小及微乳稳定性的影响。结果表明,表面活性剂、助表面活性剂、表面活性剂和助表面活性剂的质量比(Km)及油等对微乳的形成均有影响;各配方微乳的粒径均在100 nm以下,符合微乳的粒径要求,AEO-7/IPM/水,EL-40/IPM/水,EL-40/span80/IPM/水以及EL-40/span80/IPM/液体石蜡/水4种微乳体系均具有良好的稳定性和安全性,有望成为药物和化妆品的载体。     

Seminal vesicle formation and specific male protein secretion by female cells in allophenic mice

The relation of cellular sex genotype to phenotype was examined in seminal vesicles of adult allophenic mice with cellular sex chromosome mosaicism. Each animal originated from conjoined blastomeres of an embryo of female (XX) and one of male (XY) constitution, from different inbred strains. Cells of both sexes were detected in bone marrow and certain other somatic tissues; cellular sex of seminal vesicles was deduced from strain-associated electrophoretic variants of proteins coded for at autosomal loci. Seminal vesicles composed partly or entirely of female cells were found in male and pseudohermaphrodite individuals. In a pseudohermaphrodite, both allelic variants of the tissue-specific normal male seminal vesicle protein (Svp-locus) were present, signifying that female as well as male cells were synthesizing the protein. Male-determining factors on the Y chromosome are thus not required in cells that differentiate into functional seminal vesicles.     

Gelation of sickle cell hemoglobin: effects of hybrid tetramer formation in hemoglobin mixtures

The altered gelation behavior found in mixtures of sickle cell hemoglobin with other hemoglobins is due to the formation of hybrid hemoglobin tetramers from unlike dimers. The hemoglobins need not possess the deoxy quaternary structure for gelation to occur; liganded forms are also capable of participation in gelation.     

塔河油田集输管道内FeS的形成及自燃风险

塔河油田集输管道输送介质具有高含H,s、高含CO,及高含氯离子的特点,在无氧且低流速环境下,易生成FeS等腐蚀产物,FeS具有自燃性,一旦发生自燃将会引发火灾和爆炸事故。采用X-射线衍射测试方法对腐蚀产物组分进行分析,在H2S、CO2共存体系下,腐蚀产物以FeCO3、FeO（OH）、Fe3O4为主,铁的硫化物以FeS为主,但含量较低。采用加热的方式,利用固体自燃点测试仪对不同组分的7个腐蚀产物混合物进行自燃特性分析,结果表明：FeCO。可以表现出一定放热,但不会发生自燃;对于FeCO3与FeS形成的混合物,当两者质量比为15：10、单质硫磺的质量分数为2．67％时,FeCO。和FeS混合物自燃点为189．08℃,易发生自燃,建议在现场断管作业中采取预防FeS自燃的措施。（图2,表2,参6）。     

Co-treatment with surfactant and sonication signifi cantly improves Agrobacterium-mediated resistant bud formation and transient expression efficiency in soybean

Soybean is a widely planted genetically modified crop around the world. However, it is still one of the most recalcitrant crops for genetic transformation due to the difficulty of regeneration via organogenesis and some factors that affect the transformation efficiency. The percentages of resistant bud formation and transient expression efficiency are important indexes reflecting the regeneration and transformation efficiency of soybean. In this study, the percentages of resistant bud formation and transient expression of β-glucuronidase(GUS) were compared after treatment with sonication or surfactant and co-treatment with both. The results showed that treatment with either sonication or surfactant increased the percentage of resistant bud formation and transient expression efficiency. The highest percentages were acquired and significantly improved when cotyledon node explants were co-treated with sonication for 2 s and surfactant at 0.02%(v:v) using two different soybean genotypes, Jack and Zhonghuang 10. The improved transformation efficiency of this combination was also evaluated by development of herbicide-tolerant soybeans with transformation efficiency at 2.5–5.7% for different genotypes, which was significantly higher than traditional cotyledonary node method in this study. These results suggested that co-treatment with surfactant and sonication significantly improved the percentages of resistance bud formation, transient expression efficiency and stable transformation efficiency in soybean.     

表面活性剂在食品工业中的应用

简要地介绍了应用于食品工业中的表面活性及其在食品工业中的主要作用，并对表面活性剂食品制作中的一些特殊应用作了简要论述。     

Preferred microtubules for vesicle transport in lobster axons

The hypothesis that transported vesicles are preferentially associated with a subclass of microtubules has been tested in lobster axons. A cold block was used to collect moving vesicles in these axons; this treatment caused the vesicles to accumulate in files along some of the microtubules. Quantitative analysis of the number of vesicles associated with microtubule segments indicated that lobster axons have two distinct populations of microtubules--transport microtubules that are the preferred substrates for vesicle transport and architectural microtubules that contribute to axonal structure.     

阴离子表面活性剂对土壤吸附噻吩磺隆的影响

采用振荡平衡法研究了阴离子表面活性剂十二烷基硫酸钠(SDS)存在下噻吩磺隆在2种土壤中的吸附行为.结果表明:SDS会使噻吩磺隆在红壤中的吸附量减少,但随着SDS质量浓度的增大,噻吩磺隆的吸附常数呈现增加—减少—增加的变化趋势;噻吩磺隆在河潮土中的吸附受SDS的影响更为复杂,表现为较低质量浓度(小于700 mg/L)的SDS减少噻吩磺隆的吸附量,而较高质量浓度(700～900 mg/L)的SDS则增加噻吩磺隆的吸附量.SDS对噻吩磺隆在2种土壤中的吸附均可用Freundlich吸附等温式进行描述.     

三相流动条件下的油水混合物粘度

利用气液两相流压降规律相关式预测油气水三相流压降的关键是油水混合物粘度的预测。采用即时取样方法,在油气水三相流动条件下,实验测量了流型、气液速、含水率对油水混合物粘度的影响,得到了水平管内油水混合物粘度的变化规律:波浪流的油水混合物粘度大于段塞流,而段塞流的油水混合物粘度大于分层流和气团流。随着折算气速和折算液速的增大,油水混合物的粘度增加。反相前,随着含水率增大,混合物的粘度变化范围增大;反相后,随着含水率增大,油水混合物的粘度降低。随着截面高度的增加,油水混合物的粘度增加。建立相应的计算模型,其计算值与实验测量值相差-24.9%~0.93%,吻合较好。     

Self-assembly of flat nanodiscs in salt-free catanionic surfactant solutions

Discs of finite size are a very rare form of stable surfactant self-assembly. It is shown that mixing of two oppositely charged single-chain surfactants can produce rigid nanodiscs as well as swollen lamellar liquid crystals with frozen bilayers. The crucial requirement for obtaining nanodisc self-assembly is the use of H+ and OH- as counterions. These counterions then form water and lower the conductivity to 10 microsiemens per centimeter. In the case of cationic component excess, a dilute solution of nanodiscs is in thermodynamic equilibrium with a lamellar phase. The diameter of the cationic nanodiscs is continuously adjustable from a few micrometers to 30 nanometers, with the positive charge located mainly around the edges.     

Conformational switch of syntaxin-1 controls synaptic vesicle fusion

During synaptic vesicle fusion, the soluble N-ethylmaleimide-sensitive factor-attachment protein receptor (SNARE) protein syntaxin-1 exhibits two conformations that both bind to Munc18-1: a "closed" conformation outside the SNARE complex and an "open" conformation in the SNARE complex. Although SNARE complexes containing open syntaxin-1 and Munc18-1 are essential for exocytosis, the function of closed syntaxin-1 is unknown. We generated knockin/knockout mice that expressed only open syntaxin-1B. Syntaxin-1B(Open) mice were viable but succumbed to generalized seizures at 2 to 3 months of age. Binding of Munc18-1 to syntaxin-1 was impaired in syntaxin-1B(Open) synapses, and the size of the readily releasable vesicle pool was decreased; however, the rate of synaptic vesicle fusion was dramatically enhanced. Thus, the closed conformation of syntaxin-1 gates the initiation of the synaptic vesicle fusion reaction, which is then mediated by SNARE-complex/Munc18-1 assemblies.     

表面活性剂对氯虫苯甲酰胺在水溶液中光解的影响

以300 W高压汞灯为光源,研究了不同类型、不同浓度的农用表面活性剂对氯虫苯甲酰胺在水溶液中光降解行为的影响。结果表明,农乳500表现为轻微的光猝灭效应;低浓度时,随着表面活性剂十八烷基三甲基氯化铵(OTAC)浓度的增大,氯虫苯甲酰胺的光解速率逐渐增大,但当表面活性剂浓度增大到25 mg/L时,产生光猝灭效应;Tween-80对氯虫苯甲酰胺光解的影响最大,当浓度为5 mg/L、10 mg/L和25 mg/L时,光敏化率分别为16.74%、29.52%和43.17%;自制的混合表面活性剂能促进氯虫苯甲酰胺的光解。表面活性剂对氯虫苯甲酰胺在水溶液中光降解行为的影响受表面活性剂类型和剂量的影响。     

A selective activity-dependent requirement for dynamin 1 in synaptic vesicle endocytosis

Dynamin 1 is a neuron-specific guanosine triphosphatase thought to be critically required for the fission reaction of synaptic vesicle endocytosis. Unexpectedly, mice lacking dynamin 1 were able to form functional synapses, even though their postnatal viability was limited. However, during spontaneous network activity, branched, tubular plasma membrane invaginations accumulated, capped by clathrin-coated pits, in synapses of dynamin 1-knockout mice. Synaptic vesicle endocytosis was severely impaired during strong exogenous stimulation but resumed efficiently when the stimulus was terminated. Thus, dynamin 1-independent mechanisms can support limited synaptic vesicle endocytosis, but dynamin 1 is needed during high levels of neuronal activity.     

生发泡移植过程对小鼠卵母细胞体外受精的影响

为研究生发泡(GV)移植后的重组卵母细胞能充分在体外成熟和发育,本试验比较了GV移植过程及体外成熟对小鼠卵母细胞体外受精的影响。通过透明带切口及GV移植获得的重组GV期卵母细胞的成熟率为87.0%(147/169),体外受精后发育到原核期胚和2-细胞期胚的比率分别为76.2%(112/147)和42.2%(62/147),与仅做透明带切口但不进行GV移植的对照组相似(P>0.05),表明GV移植过程未对卵母细胞体外受精后的早期胚胎发育能力产生不利影响。但与体内成熟的卵母细胞相比,体外成熟卵母细胞的受精率和卵裂率都明显降低,表明其进一步发育的能力受到影响。     

Pulmonary surfactant and evolution of the lungs

Pulmonary surfactant has been looked for and found in 11 representatives of four vertebrate classes. The amount of surfactant, estimated by quantitative spreading as a surface film, correlates well with alveolar surface area and with the amount of saturated, mainly dipalmitoyl, phosphatidylcholine in the lung parenchyma. The quantities of other phospholipids do not correlate well with alveolar surface area.     

Branched threadlike micelles in an aqueous solution of a trimeric surfactant

Very long threadlike micelles observed in aqueous solutions of some surfactants have attracted much attention because of the peculiar rheological properties of these systems. Molecular dynamics simulations have suggested that branched threadlike micelles should exist in concentrated solutions of dimeric surfactants. Here experimental evidence, obtained from transmission electron microscopy at cryogenic temperature, is presented of branched threadlike micelles in aqueous solutions of a triquaternary ammonium (trimeric) surfactant made up of three amphiphilic moieties connected at the level of the head-groups by two propanediyl spacers.     

Liquid-phase dehydration of aqueous ethanol-gasoline mixtures

Two-phase mixtures of gasoline, water, and ethanol were dehydrated with both starch and saponified starch-g-polyacrylonitrile (HSPAN). Whereas starch absorbed ethanol as well as water, HSPAN selectively absorbed the water component, allowing ethanol to dissolve in the gasoline phase.