Équilibres de phases en chromatographie micellaire. Corrélation LSER de la constante d'équilibre micelle-eau

Micellar liquid chromatography allows to detemine micelle-water equilibrum constant $K_{MW}$. Capacity factors of fifty solutes of various polarities are measured using cationic and anionic micellar mobilephase and a C$_{18}$ silica column. The solvatochromic parmeters of the solutes are used to establish a convenient LSER (linear solvation equation relationship) correlations for the capacity factors. Using the Armstrong model, the micelle-water equilibrum constant $K_{MW}$ of tbe solutes used are determined d'Armstrong, The LSER equations found for $K_{MW}$ give a a straights with a correlation coefficient higher than 0.95. For the two used surfactants, The LSER coefficients found allow to conclude that the size of the solute is the most influencial parmeter on micelle-water equilibrum constant $K_{MW}$ followed by the solute basicity

Étude thermodynamique de 4 cristaux liquides contenant des substituants dioxyethylene par analyse enthalpique differentielle et chromatographie en phase gazeuse

A thermodynamic study of 4 liquid crystals with DOE substituents using gas chromatography are carried out. The 4 compounds have the same mesogenic part; they differ by the partial or total substitution of the terminal chain heptyloxy with 2-(2-methoxyethoxy)ethoxy (DOE). The thamal properties of the 4 compounds are determined by differntial scanning calorimetry. The knowledge of the gas chromatographic specific retention volume of a serial geometric isomers obtained by using the 4 liquid crystals as stationary phases allow to calculate their thermodynamic data: activity coeffients, enthalpies and entropies of solution. In the other hand, the support influence on the thermal properties are investigated. The results founds show that this parameter is not negligible but disappear when the coating increases. For silica, the transitions (melting, clarification) are apparent only when the coating is higher than 50%. With Chromosorh P, 5% of coating are sufficient to observe the transitions

Effect of Dietary n-3 Polyunsaturated Fatty Acids on Oxidant/Antioxidant Status in Macrosomic Offspring of Diabetic Rats

The aim of this work was to determine the effect of dietary n-3 PUFA on oxidant/antioxidant status, in vitro very low and low density lipoprotein (VLDL-LDL), and VLDL-LDL-fatty acid composition in macrosomic pups of diabetic mothers. We hypothesized that n-3 PUFA would improve oxidative stress in macrosomia. Diabetes was induced in female Wistar rats fed with the ISIO diet (control) or with the EPAX diet (enriched in n-3 PUFAs), by streptozotocin. The macrosomic pups were killed at birth (day 0) and at adulthood (day 90). Lipid parameters and VLDL-LDL-fatty acid composition were investigated. The oxidant/antioxidant status was determined by measuring plasma oxygen radical absorbance capacity (ORAC), hydroperoxides, carbonyl proteins, and VLDL-LDL oxidation. Macrosomic rats of ISIO fed diabetic mothers showed an increase in plasma and VLDL-LDL-triglycerides and VLDL-LDL-cholesterol levels and altered VLDL-LDL-fatty acid composition. Plasma ORAC was low with high hydroperoxide and carbonyl protein levels. The in vitro oxidizability of VLDL-LDL was enhanced in these macrosomic rats. The EPAX diet corrected lipid parameters and improved oxidant/antioxidant status but increased VLDL-LDL susceptibility to oxidation. Macrosomia is associated with lipid abnormalities and oxidative stress. n-3 PUFA exerts favorable effects on lipid metabolism and on the oxidant/antioxidant status of macrosomic rats. However, there are no evident effects on VLDL-LDL oxidation

The Multifrontal Method

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MUMPS

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