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991.
Itaru Yamashita Youhei Kawabata Tadashi Kato Masakatsu Hato Hiroyuki Minamikawa 《Colloids and surfaces. A, Physicochemical and engineering aspects》2004,250(1-3):485-490
Small angle X-ray scattering (SAXS) is measured for the lamellar phase in aqueous systems of 1-o-β-3,7-dimethyoctyl-D-glucopyranoside (β-Glc(Ger)), which has recently been prepared by us, 1-o-β-decyl-D-glucopyranoside (β-GlcC10), and 1-o-β-octyl-D-glucopyranoside (β-GlcC8). The repeat distance d obtained from the position of the diffraction peak does not follow the swelling law d = 2δhc/hc, where δhc and hc are the thickness and the volume fraction of the hydrophobic layer, respectively. This may result from the fact that δhc increases and, equivalently, the surface area per surfactant molecule (as) decreases with increasing concentration. So we calculate δhc and as from the observed d value at each concentration using the above swelling law. The half-thickness δhc increases in the order β-GlcC8 < β-Glc(Ger) < β-GlcC10 at a fixed concentration. On the other hand, the data on as for β-GlcC10 and β-GlcC8 lie on the same line and the data for β-Glc(Ger) lies above this line. These results suggest that the cross-sectional area of the geranyl chain is larger than that of the glucose headgroup. Existence of water filled defects in bilayer sheets is also discussed based on the SAXS pattern and the concentration dependence of d. 相似文献
992.
β-Cyclodextrin-polyurethane polymer as solid phase extraction material for the analysis of carcinogenic aromatic amines 总被引:1,自引:0,他引:1
β-Cyclodextrin-polyurethane (β-CDPU) polymer was synthesized by the reaction of β-cyclodextrin with hexamethylene diisocyanate in dry dimethylformamide and used as a sorbent for the solid phase extraction (SPE) of carcinogenic aromatic amines from water. The polymers were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry and particle size analysis. The separation and quantification was performed by Liquid chromatography with RP-C18 column and diode array detection using standard arylamines for quantification. When compared with commercially available sorbents, β-CDPU gave better recovery for the aromatic amines. From the variation of pH of the extractant from 4.0 to 8.5 recovery was highest at pH 8.5. The breakthrough volume has been ascertained to be 100 ml for 200 mg of the resin. The new SPE material offers better recovery and estimation of banned arylamines. 相似文献
993.
Reversed phase high performance liquid chromatography (RPLC) is currently the method of choice for the analysis of basic compounds. However, with traditional silica materials, secondary interactions between the analyte and residual silanols produce peak tailing which can negatively affect resolution, sensitivity, and reproducibility. In order to reduce these secondary interactions, which comprise ion exchange, hydrogen bonding, and London forces interactions, chromatographic analyses can be carried out at low or high pH values where silanol groups and basic compounds are mostly uncharged. The chromatographic behaviour of a particular bidentate stationary phase, Zorbax Extend C18, was studied with a set of basic and neutral compounds. Thanks to a higher chemical stability than traditional silica based supports, analyses were carried out with a high pH mobile phase, which represents a good alternative to the acidic mobile phases generally used to reduce ion exchange interactions. The performance of this bidentate stationary phase was also compared with that of other supports and it was proved that it is advantageous to work with high pH mobile phases when analyzing basic compounds. 相似文献
994.
The surface pressure-molecular area curve of the mixed monolayer of 16-(9-anthroyloxy) palmitic acid (16AP) and fatty acid (palmitic or stearic acids) showed various kink points which indicated the phase transitions of the monolayer. On the basis of the surface phase rule, the phase diagrams of the mixed monolayer were elucidated. The bifunctional molecule, 16AP, takes two orientations in a monolayer state, that is, horizontal and vertical ones. Horizontally oriented 16AP and vertically oriented fatty acid form a mixed monolayer but this exhibits deviation from the ideal mixing, which was interpreted in terms of the surface regular solution theory. On the other hand, the 16AP molecule in the vertical state was found to be immiscible with the fatty acid molecule in a monolayer de spite both molecules being vertical to the surface and parallel to each other. This was caused by the participation of the 9-anthroyloxy moiety of 16AP in the interaction of 16AP and fatty acid in the hydrophobic region of the monolayer. 相似文献
995.
A non ionic surfactant with a rigid rod-like hydrophobic group has been synthesized. Owing to the molecular geometry of the surfactant only lamellar micelles are formed in aqueous solution.This system exhibits a lyotropic nematic phase (N
L), which for the first time has been found for a binary non ionic surfactant/water system.Herrn Professor Dr. H.-G. Kilian mit herzlichen Glückwünschen zum 60. Geburtstag gewidmet. 相似文献
996.
介绍了不同孔径的硅胶聚合物键合相的合成,比较了其对蛋白质的分离特性。结果表明,大孔径的硅胶聚合物键合相比表面积小,易于获得生物大了分子的快速分离。 相似文献
997.
E. Fernández-Sánchez A. Fernández-Torres J. A. García-Domínguez J. M. Santiuste 《Chromatographia》1991,31(1-2):75-79
Summary A correlation between the retention polarity and the Kováts' coefficient has been found for a number of commercial stationary phases used in gas chromatography. The correlation has been used to predict the polarity of a few mixed stationary phase columns prepared as binary mixtures of OV-101 with OV-25, DC-550 or Carbowax 20M, and also mixtures of OV-225 with SP-2340. A linear relationship was found between polarity and mixture composition. The temperature dependence of the Kováts' coefficient was investigated and found to increase linearly with temperature, the rate of increase depending on the polarity of the stationary phase, with greater increases for more polar stationary phases. 相似文献
998.
El-B. Yallaoui 《Periodica Mathematica Hungarica》1991,23(2):109-120
Let X be an abstract set and L a lattice of subsets of X. To each lattice regular measure µ, we associate two induced measures
and
on suitable lattices of the Wallman space IR(L) and another measure µ on the spaceIR(L). We will investigate the reflection of smoothness properties of p onto
,
and µ; and try to set some new criterion for repleteness and measure repleteness. 相似文献
999.
We give a necessary and sufficient condition for the uniformly non-l
n
(1)
property of Musielak-Orlicz sequence spacesl
Φ generated by a sequence Φ=(ϕn:n⩾l) of finite Orlicz functions such that
for eachn∈ℕ. As a result, forn
0⩾2, there exist spacesl
Φ which are only uniformly non-l
n
(1)
forn⩾n
0. Moreover we obtain a characterization of uniformly non-l
n
(1)
and reflexive Orlicz sequence spaces over a wide class of purely atomic measures and of uniformly non-l
n
(1)
Nakano sequence spaces. This extends a result of Luxemburg in [19].
Submitted in memory of Professor W. Orlicz 相似文献
1000.
We study wild embeddings of S
1 in S
n which are tame in a sense introduced by Quinn. We show that if is a finitely presented group with H
1()=H
2()=0, then any finiteness obstruction K
0() can be realized on the complement of such an embedded S
1. We also realize trivially symmetric K
–1() obstructions on the complements of such embeddings. For trivially symmetric , the embeddings constructed are shown to be isotopy homogeneous. 相似文献