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41.
42.
微乳液进样火焰原子吸收光度法测定食品中的微量锰 总被引:8,自引:0,他引:8
研究了多种表面活性剂及微乳液对火焰原子吸收光谱法测定锰的增敏作用,并选择增敏作用最强的微乳液作为锰测定的增敏试剂,拟定了测定锰的新方法。 相似文献
43.
《Journal of Dispersion Science and Technology》2013,34(6):563-567
A water-in-oil (w/o) microemulsion was prepared with the zwitterionic surfactant dodecyl betaine (C12BE), n-pentanol (C5OH), n-heptane (C7H16) and water. Effects of polyvinylpyrrolidone (PVP) with different molecular weight on the state of water in w/o microemulsions at a given water/C12BE molar ratio were investigated by FT-IR and differential scanning calorimetry (DSC). The experimental results showed that addition of PVP resulted in an increase of the content of the bound water in water pool of a w/o microemulsion, but a decrease of the amount of the bulky water. The higher the molecular weight of PVP, the more bound water; and the less bulk water. The change of the trapped water was not obvious due to the interference of C5OH. 相似文献
44.
This paper describes the dynamics of a water-in-oil microemulsion from the dilute to the dense droplet region. Using the relative intermediate form factor method for neutron spin echo data analyses [M. Nagao, H. Seto, Phys. Rev. E 78 (2008) 011507], the shape and structure fluctuations of a droplet microemulsion are successfully decoupled. In the previous paper, we used the first cumulant analysis of the shape fluctuation model, while the full fitting form of the same model is applied in this paper. The final results of the fittings using the first cumulant approximation and the full form of the model are almost identical, and therefore, the validity of the method is strengthened. The estimated bending modulus of the surfactant membrane, κ, is basically the same, within the experimental errors, in the previous and present results. The κ is not affected much by an increase of the droplet concentration. A clear dynamic slowing down of the water droplets is highlighted at the length scale corresponding to the inter-droplet distance from the structure fluctuation analysis. 相似文献
45.
La0.45Ce0.45F3:Tb (10 mol% Tb) nanoparticles was synthesized via sonochemical method and then coated with silica (SiO2) shells through a microemulsion process, resulting in the formation of core/shell structured LaCeF3:Tb/SiO2 nanoparticles. The obtained core/shell LaCeF3:Tb/SiO2 nanoparticles are spherical and uniform in size (average size about 60 nm), strongly fluorescent, and long fluorescence lifetime
(1.87 ms). This kind of nanoparticles was water-soluble, which could be applied in biological labeling and other fields. 相似文献
46.
K. S. Birdi 《Colloid and polymer science》1982,260(6):628-631
In microemulsions consisting of four components, i.e. detergent — water — oil — cosurfactant, the free energy of transfer from the continuous oil phase to the interfacial region for the cosurfactant is reported. From the effect of temperature on the free energy, the entropy and the enthalpy values are also reported. The effect of chain length of the alcohol (cosurfactant) is also described. It is further shown, that if the oil phase consists of hexadecane, then the free energy changes as a linear function of the number of carbon atoms in the cosurfactant. On the other hand, if the oil phase is benzene, the cosurfactant chain length has very little effect. These data are analyzed with respect to the microemulsion structure and stability. 相似文献
47.
Quenching of fluorescence of the dye 3,7-diamino-2,8-dimethyl-5-phenyl Phenazinium Chloride (Safranine T) has been investigated by AgCl nanoparticles in the W/O microemulsion medium at different [H2O]/[AOT] ratios (ω) and with Ag nanoparticles and Ag+ in aqueous medium. A simple straightforward method has been introduced to prepare AgCl nanoparticles in well-characterized, monodispersed biomimicking nanocavities formed by sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in heptane. Experimental results reveal that the size of the AgCl nanoparticles increases with increase in hydration. The results of the quenching experiment were analysed in the light of Stern Volmer equation. Quenching of fluorescence of the dye has been found to decrease with decrease in the size of the nanoparticles of AgCl and the variation of Stern Volmer quenching constants (KSV) with particle size is different for two different size regimes. 相似文献
48.
49.
An enhancement of palladium-catalyzed Suzuki cross-coupling reactions between substrates possessing long-chain alkyl or oxyalkyl substituents in two-phase media, in the presence of sodium dodecylsulfate, is shown. Quantitative evaluations of the influence of SDS on the reaction rates were determined. 相似文献
50.
TIAN Qing-ping LI Peng XIE Ke-chang .Key Laboratory of Coal Science Technology Ministry of Education Shanxi Province Taiyuan University of Technology Taiyuan P.R.China 《高等学校化学研究》2009,25(1)
In order to solve the drawback of poor bioavailability by the oral route and infusion-related side effect for Amphotericin B(AmB), microemulsion vehicles composed of isopropyl myristate(IPM), Tween 80, isopropyl alcohol and water for transdermal delivery of AmB were designed. The pseudo-ternary phase diagrams were constructed by the H2O titration method and the structures of the microemulsion were determined by measuring electrical conducti-vities(σ). The diffusion studies of AmB microemulsion were performed via excised rabbit skin on a drug diffusion apparatus. To obtain a high solubization of AmB, three different methods were tested to incorporate AmB into mi-croemulsion. The result suggests adding AmB in the shape of NaOH solution to the O/W blank microemulsion over the phase inversion temperature(PIT) of the emulsifier obtains the maximum drug content(2.96 mg/mL). The pH value of the system could be adjusted to pH8.5 or pH<5.2, in this range AmB molecules converts from aqueous to the hydrophilic shell of the microemulsion droplets, drug precipitate is no more than 5%, and the formulations were corresponding to the characterizations of microemulsion. At pH 5.14, AmB microemulsion with Km 1:1, O/SC 1:9(mass ratio ofoil phase to surfactant/cosurfactant blend), water content 64.6%, drug content (2.93±0.08) mg/mL,showed the maximum permeation rate(3.255±0.64)μg·cm-2·h-1,which is stable for a long time. 相似文献