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41.
In the context of the density functional theory of the local electron density the valence and differential density distribution in crystalline sulfates of M2SO4 (M is Li, Rb, and Cs) and double sulfates of MLiSO4 were calculated using the pseudopotential method in the basis set of numerical atomic pseudo-orbitals. It is shown that in lithium sulfate crystallographically inequivalent oxygen atoms are in different charge states and have a different force of chemical bonding with sulfur. Anions are bonded to each other through lithium atoms that form tetrahedral complexes with oxygen. In rubidium sulfates the electron clouds of the anions overlap and chain structures form. Chemical bonding between the anion and the cation has an ionic nature. These features of the electron structure manifest themselves in double sulfates, where LiO4 complexes that link the anionic chains also form, and heavy metals serve as cations. 相似文献
42.
The effects of sodium dodecyl sulfate on extracellular lipase produced byCandida lipolytica have been studied. The microorganism was grown in culture medium containing different sodium dodecyl sulfate concentrations
added to the culture at different intervals of growth. The extracellular lipase activity was not detected when the treated
culture supernatants were directly tested in Yeast Mold Agar-Triolein-Rhodamine plates, regardless of surfactant addition
time and concentrations. However, after ammonium sulfate precipitation and dialysis, the extracellular lipase activity could
be recovered. Therefore, the surfactant, under the experimental conditions used here, does not seem to be able to inhibit
lipase production, but it does inhibit the enzyme activity because of its presence in the mixture of the reaction. 相似文献
43.
Various types of sodium cellulose sulfate (SCS), dissolved in a 1M LiCl solution, were investigated by alternating current (AC)polarography. The SCS samples differed in the degree of substitution (DS), thedistribution of substituents within the anhydroglucose unit (AGU), and alongthechain, due to the method of synthesis. The goal was to study theelectrosorptionbehavior, characterized by the shape of the desorption wave in the polarogram,as a function of the chemical structure of the SCS samples. The shape of thedesorption wave reflects domains of different substitution. A superimpositionofparameters like DS and pattern of substitution on the electrosorption behaviorwas observed. The AC polarography method described can be used as a tool todistinguish between an even or uneven distribution of substituents along thecellulose chain. 相似文献
44.
45.
Methyl methacrylate and butyl methacrylate were polymerized in oil-in-water microemulsions that were stabilized by sodium dodecyl sulphate (SDS). A poly(N-acetylethylenimine) (PNAEI) macromer was also included in the recipe, as a cosurfactant and a comonomer. Polymerizations were initiated by UV-irradiation. The average diameters of latex particles, obtained by STM, were in the range of 17-200 nm. The experimental data evidenced that the particle size was mainly dependent on the SDS/PNAEI ratio. Polymerization yields were around 75-85%. The synthesized copolymers have viscosity average molecular weights in the range of 2.1-2.4×106 and glass transition temperatures of 38.0-43.5°C, lower than those obtained without using PNAEI. The investigation by means of FTIR and 1H-NMR techniques revealed that PNAEI was incorporated into the nanoparticles. 相似文献
46.
研究了烷基硫酸钠纯度,烷基碳链分布对甲基丙烯酸甲酯种子乳液聚合反应的影响。结果表明,烷基硫酸钠中乙醇不溶物含量的增加,可提高MMA乳液聚合反应速度,在采用K2S2O8-NaHSO3-Cu^2+三元氧化-还原引发体系的MMA乳液聚合中,Fe^2+降低反应速率,而Fe^3+则提高聚合反应速率; 相似文献
47.
48.
The chemiluminescence (CL) of peracetic acid (PAA) in alkaline medium is very weak but is strongly enhanced after the addition
of dihydralazine sulfate (DHZS). Based on this phenomenon, a simple, rapid and highly sensitive flow-injection CL method for
the determination of DHZS was developed. The CL emission was linearly related to the DHZS concentration in the range of 20–4000 ng mL−1 with a detection limit (3σ) of 1.2 ng mL−1. As a preliminary application, the proposed method was successfully applied to the determination of DHZS in pharmaceutical
preparations; the recovery of DHZS in human urine was between 96.5% and 102.2%. A detailed CL mechanism was proposed and singlet
molecular oxygen (1O2) was suggested to be produced in the CL reaction process. 相似文献
49.
J. L. Oscarson R. M. Izatt P. R. Brown Z. Pawlak S. E. Gillespie J. J. Christensen 《Journal of solution chemistry》1988,17(9):841-863
The aqueous reactions,
相似文献
50.
SANS data have been obtained for C12H25 (OC2H4)2SO4 Na. Results have been obtained for i) a series of solutions of variable concentration of the surfactant, ii) an approximately 0.07 M surfactant concentration to which variable amounts of NaCl were added, iii) a series of solutions 0.058M in surfactant but in different D2O-H2O mixtures. The SANS data can be described in terms of a model of monodispersed hard spheres interacting via a screened Coulombic potential. The micelles seem to be able to tolerate substantial amounts of salt without changing the internal structure. 相似文献
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