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71.
72.
Summary The technique of an internal pH gradient induced by the sample is applied to the separation of proteins by liquid chromatography. Compatibility of the method with microcolumns is demonstrated and examples of separations on different types of sorbents are given. 相似文献
73.
离子交换法从发酵液中提取谷氨酰胺工艺研究 总被引:12,自引:0,他引:12
本文系统地研究了732树脂和D301树脂对发酵液中谷氨酰胺的静态和动态吸附性能及影响因素,并对洗脱条件进行了研究。实验结果表明,在阳离子交换柱上有效地降低了谷氨酰胺向谷氨酸的转化,在阴离子交换柱上谷氨酰胺和谷氨酸实现彻底分离,谷氨酰胺的总收率达56.6%。 相似文献
74.
Summary The effect of composition and flow rate of the mobile phase on the HPLC separation of hydrogenated buckminsterfullerene (C60Hn n=2–38) was investigated on BuckySep column. Toluene was used as the basic solvent and hexane, heptane, cyclohexane, THF,
acetonitrile, acetone, ethanol and 2-propanol as co-solvents. The fraction of co-solvents was varied 10–80%, and the flow
rate 1–0.1 mL min−1. Toluene-acetonitrile 65∶35 and toluene-acetone 50∶50 provided the best separation. Under the best conditions complete separation
of C60H2 and almost complete separation of the four most abundant isomers of C60H4 were achieved. Separation of derivatives with higher hydrogen content was very poor.
Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997 相似文献
75.
A theoretical model for the dynamic surface tension of an air bubble expanding in micellar surfactant solution is proposed. The model accounts for the effect of expansion of the bubble surface during the adsorption of surfactant molecules (monomers) and the effect of disintegration of polydisperse micelles on the surfactant diffusion. Assuming small deviations from equilibrium and constant rate of expansion analytical expression for the surface tension and the subsurface concentration of monomers as a function of time is derived. The characteristic time of micellization is computed from the experimental data for two surfactants (sodium dodecyl sulfate and nonylphenol polyglycol ether) obtained by the maximum bubble pressure method. 相似文献
76.
Ivan panik Jan Krupcik Ivan Skacani Jaap De Zeeuw Mario Galli Pat Sandra 《Journal of separation science》1997,20(12):688-692
The separation of isomers and enantiomers of branched C10-C12 phenylalkanes by gas chromatography on fused silica capillary columns coated with some modified β- and γ-cyclodextrins was studied. It was shown that the separation of positional isomers of C10-C12 phynylalkanes on modified cyclodextrin capillary columns is not better than that on a column coated with modified polyethylene glycol. Differences were found in the enantioselectivity of modified β- and γ-cyclodextrins for the separation of C10-C12 secondary phenylalkane enantiomers. While alkylderivatives of β-CDs resolve enantiomers of 3-phenylalkanes, alkyl derivatives of γ-CD resolve enantiomers of 2-phenylalkanes. Since shape selectivity factors of modified cyclodextrins have indicated no inclusion of the considered solutes in cyclodextrin cavities, enantioselective interactions most probably occur on the outer sphere of cyclodextrins. 相似文献
77.
78.
Literature data on distribution ratios (Dw) of Np(V) and Pa(V) for the AG1-X8 resin are scarce whereas those related on resin capacity factors (k′) values for TEVA, TRU and U/TEVA resins are absent. Therefore, batch extraction experiments for Pa(V) and Np(V) from HCl and HNO3 media were realized, at tracer scale, with AG1-X8 and EIChroM resins (TEVA, TRU and U/TEVA). Based on the new Dw and k′ values obtained in this study, a new protocol for Pa/Np separation has been developed leading to a better separation factor of 105 and a chemical yield of 97 ± 3% and 99 ± 1% for Pa and Np, respectively. A separation of 231Pa from uranium matrix was successfully tested. 相似文献
79.
The development of analytical methods and strategies to determine gadolinium and its complexes in biological and environmental matrices is evaluated in this review. 相似文献
80.
Experiments were carried out to observe the effect of a magnetic field and grid biasing voltage in presence of a plasma bubble in a magnetized, filamentary discharge plasma system. A spherical mesh grid of 80% optical transparency was negatively biased and introduced into the plasma for creating a plasma bubble. Diagnostics via an electrical Langmuir probe and a hot emissive probe were extensively used for scanning the plasma bubble. Plasma floating potential fluctuations were measured at three different positions of the plasma bubble. The instability in the pattern showed the dynamic transition from periodic to chaotic for increasing magnetic fields. Time scale analysis using continuous wavelet transform was carried out to identify the presence of non‐linearity from the contour plots. The mechanisms of the low‐frequency instabilities along with the transition to chaos could be qualitatively explained. Non‐linear techniques such as fast Fourier transform, phase space plot, and recurrence plot were used to explore the dynamics of the system appearing during plasma fluctuations. In order to demonstrate the observed chaotic phenomena in this study, characteristics of chaos such as the Lyapunov exponent were obtained from experimental time series data. The experimentally observed potential structure is confirmed with numerical analysis based on fluid hydrodynamics. 相似文献