Counterion Exchange Selectivity in Detergent–Polymer Aggregates

In aqueous solution, the interaction between sodium dodecyl sulfate (SDS) and poly(ethylene glycol) (PEG) results in the formation of small aggregates or clusters of SDS attached to the PEG polymer chain. Selectivity coefficients for exchange of two monovalent (N-methyl-4-cyanopyridinium cation and Tl⁺) and two divalent (methylviologen cation and Cu²⁺) counterions at the surface of SDS–PEG clusters, determined employing photophysical techniques, are similar, but not identical, to those for exchange at the surface of SDS micelles in the absence of PEG. The principal factor affecting ion exchange selectivity in SDS–PEG clusters does not appear to be aggregate size or surface charge density but rather the presence of poly(oxyethylene) subunits at the aggregate surface.     

对钠离子有选择性的中性载体

合成了十一种中性离子载体,用它们制成钠离子选择性电极,测定了电极的选择性系数并与文献报道的类似电极进行了比较。     

Excess enthalpies of solution of some primary and secondary alcohols in sodium dodecylsulfate micellar solutions

The exces enthalpies of solution of some primary and secondary alcohols in aqueous sodium dodecylsulfate micellar solutions were measured and the results were explained by considering the distribution of alcohols between aqueous and micellar phases. The distribution constant and the enthalpy of transfer (and the standard free energy and entropy of transfer) were obtained. The thermodynamic parameters for the transfer of secondary alcohols from the aqueous to the sodium dodecylsulfate (NaDS) micellar phase differ slightly from those of the corresponding primary alcohols. For both series of alcohols the additivity rule holds for free energies of transfer whereas enthalpies and entropies display convex curves. The present data are compared to those for the transfer of the same solutes from the aqueous to the dodecyldimethylamine oxide (DDAO) and dodecyltrimethylammonium bromide (DTAB) micellar phases. The role of the hydrophilic interactions between the OH group and the micelles' head groups is formulated. The thermodynamics of the branched methyl group were determined. Furthermore, the thermodynamics of solvation of primary alcohols in water, in NaDS micelles, and in octane have been calculated using reference states based on the assumption that the empty space around alcohols in the initial and final states is the same. It is shown that the solvation of alcohols in NaDS micellar phase is enthalpy driven and that the thermodynamic properties of solvation vs. the length of the alcohol tail is the same for water and NaDS micelles whereas it is different for octane. A possible explanation for this difference is that the alkyl chain of alcohols folds in octane.     

吸收比-系数倍率法及其应用——水杨酸钠、安替比林和咖啡因的同时测定

用吸收比－系数倍率法同时测定撒痛风注射液中水杨酸钠、安替比林和咖啡因三组分的含量。它们的回收率分别为１００．７％～１０２．１％、９５．９３％～１０４．５％和９７．５７％～１０１．７％。     

细胞分裂素对大豆叶片衰老过程中蛋白激酶基因表达的影响

利用真核生物催化丝氨酸／苏氨酸残基磷酸化的蛋白激酶ＶＩ和Ⅷ保守区设计兼并引物,进行ＲＴ－ＰＣＲ扩增反应,研究大豆叶片衰老过程中蛋白激酶基因表达的变化及外源细胞分裂素处理的作用。结果表明人工合成的细胞分裂素－６ＢＡ预处理很可能在转录水平上正向调节一些蛋白激酶基因的表达,而诱导衰老处理则起负调控作用。     

用强碱性阴离子交换树脂从碳酸盐溶液中回收铀的研究 2.U(Ⅵ)在溶液相与树脂相的化学状态

在过量碳酸盐存在的Ｕ（Ⅵ）溶液中,Ｕ（Ⅵ）的化学状态与溶液的ｐＨ值有关,当ｐＨ＞８时,Ｕ（Ⅵ）以［ＵＯ２（ＣＯ３）３］４－离子存在．吸附于树脂相的Ｕ（Ⅵ）的化学状态也与供吸附的料液的ｐＨ值有关,当ｐＨ＞９时,Ｕ（Ⅵ）才完全以［ＵＯ２（ＣＯ３）３］４－吸附于树脂相．当ｐＨ在６．５～８．０范围时,Ｕ（Ⅵ）在溶液中还可能以［ＵＯ２（ＣＯ３）２］２－或Ｈｎ［ＵＯ２（ＣＯ３）３］ｎ－４形式存在,而Ｕ（Ⅵ）以［ＵＯ２（ＣＯ３）２］２－形式吸附于树脂相的可能性很小,它主要以Ｕ２Ｏ２－７的形式吸附于树脂相．     

四元体系Na2B4O7—Na2CO3—NaCl—H2O在0℃时的等温溶度研究

第一次用等温方法测定了含硼酸盐的三元边界体系Ｎａ２Ｂ４Ｏ７－ＮａＣｌ－Ｈ２Ｏ和四元体系Ｎａ２Ｂ４Ｏ７－Ｎａ２ＣＯ３－ＮａＣｌ－Ｈ２Ｏ在０℃时的溶度。结果发现它们都是低共饱型体系。在三元体系中共饱点组成为ＮａＣｌ２６．１９％,Ｎａ２Ｂ４Ｏ７０．３６％（质量）;四元体系中共饱点组成为ＮａＣｌ２３．５５％,Ｎａ２Ｂ４Ｏ７０．６２％,Ｎａ２ＣＯ３４．０７％（质量）,并且绘出了四元体系中的溶度图和等水线。     

Surface modified precipitated calcium carbonates at a high degree of dispersion

Calcium carbonates of different degrees of surface hydrophobicity were obtained when sorbic acid or polyoxyethylene glycol were present during the precipitation. In the presence of trace amounts of divalent cations carbonates with high surface hydrophilicity and improved monodisperse character are obtained. Surface modification of the calcium carbonates by several proadhesive compounds can markedly improve the chemical affinity of the carbonates to polymers. Very effective are isostearoyl titanate and two polyoxyethylene compounds. Precipitated calcium carbonates modified with 2 to 3 percent (wt/wt) of isostearoyl titanate increased the tensile strenght of butadiene-styrene rubber by approximately 100%. Polyurethane is only strengthened when 30 wt/wt of a filler are introduced independently of the type proadhesive compounds. The best strength and hysteresis of polyurethanes are obtained with calcium carbonate modified with 2 percent (wt/wt) of polyoxyethylene glycol.     

Glass capillary gas chromatography of amino acid enantiomers

Glass capillaries coated with Chirasil-Val, a chirally functionalised polysiloxane, are capable in principle of resolving all protein amino-acid enantiomers in a single run and within a short analysis time, thus allowing for example the quantitative amino acid determination by enantiomer labelling. The elution characteristics of the individual amino acids however are also dependent upon the chemical nature of the capillary wall surface, and a surface pretreatment is found to be necessary if all protein amino acids are to be analysed. Of the various methods of pretreatment tested, etching of borosilicate glass with gaseous HCl followed by deposition of colloidal silicic acid is considered to be the most suitable.     

Evaluation of recombinant green fluorescent protein, under various culture conditions and purification with HiTrap hydrophobic interaction chromatography resins

To determine the influence of various culture conditions, transformed cells of Escherichia coli expressing recombinant green fluorescent protein (GFPuv) were grown in nine cultures with four variable conditions (storage of inoculated broth at 4°C prior to incubation, agitation speed, isopropyl-β-d-thiogalactopyranoside [IPTG] concentration, and induction time). The pelleted cells were resuspended in extraction buffer and subjected to the three-phase partitioning (TPP) extraction method. To determine the most appropriate purification resin, protein extracts were eluted through one of four types of HiTrap hydrophobic interaction chromatography (HIC) columns prepacked with methyl, butyl, octyl, or phenyl resins and analyzed further on a 12% sodium dodecylsulfatepolyacrylamidegel. With Coomassie staining, a single band between 27 (standard GFPuv) and 29 kDa (molecular weight standard) was visualized for every HIC column sample. TPP extraction with HIC elution provided about 90% of the GFPuv recovered and eight-fold GFPuv enrichment related to the specific mass. Rotary speed and IPTG concentration showed, respectively, greater negative and positive influences on GFPuv expression at the beginning of the logarithmic phase for the set culture conditions (37°C, 24-h incubation).