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JPC - Journal of Planar Chromatography - Modern TLC
Authors: Tamás Csermely, Georg Petroianu, Kamil Kuca, Józsel Fűrész, Ferenc Darvas, Zsolt Gulyás, Rudolf Laufer, and Huba Kalász

Quaternary pyridinium aldoximes have been analyzed by thin-layer chromatography. Their separation was adequate when silica plates were used with a mobile phase with a high water content. As a consequence of their limited migration, reversed-phase TLC was not appropriate for determination of the lipophilicity of quaternary pyridinium aldoximes. Displacement TLC of some quaternary pyridinium aldoximes is, nevertheless, possible using silica as stationary phase with water-acetone-hydrochloric acid mobile phases. Normal-phase TLC with different concentrations of organic modifier gave a series of R M values for the pyridinium aldoximes. Approximation of the different plots of R M against organic modifier concentration to straight lines afforded R M,0 values and the slopes of the lines. The R M,0 values and the slopes both serve as indicators of the hydrophilic character of the compounds.

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The changes of cell surface hydrophilicity in Bacillus subtilis were analyzed in response to oxygen-limitation, heat shock, salt stress, pH-shock, phosphate- and carbon-limitation.  Although cell surface hydrophilicity varied during growth phases, an increase of surface hydrophilicity was observed under several of these stress conditions.  An observed drop in intracellular GTP and/or ATP may be an element of the signal transduction pathway leading to an increase in surface hydrophilicity in response to environmental stresses.  Attachment of cells to soil particles under salt stress conditions is strongly influenced by the degS/degU two-component system, which thereby provides a mechanism for the bacteria to escape from the hostile environment.

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This paper presents the measurements of bulk density, matrix density, total open porosity, water absorption coefficient, water vapor diffusion resistance factor and thermal conductivity of hydrophilic mineral wool Front — Rock Max E. Front — Rock Max E consisted of two layers fasten together, namely a low-density and high-density layer.

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Abstract  

High-density polyethylene, its composites with hydrophilic/hydrophobic silica and the antioxidant BHT (butylated hydroxytoluene) were studied using the thermogravimetric analysis. It has been shown that filling with silica as well as introducing BHT into the unfilled polymer increases the thermal-oxidative stability of the polymer. Immobilized BHT is inactive and it suppresses the stabilizing effect of hydrophobic silica surface in the processes of thermal oxidation at the initial stage. However, being gradually released from the surface antioxidant prolongs the resistance of the polymer against oxidation.

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A model for the interactions involving hydrophilic structure maker solutes

A thermodynamic study of ternary aqueous solutions of glucose and hydroxylated substances

Journal of Thermal Analysis and Calorimetry
Authors: Giuseppina Castronuovo, V. Elia, and Filomena Velleca

Enthalpies of dilution of ternary aqueous solutions containing glucose and alkan-1-ols, alkan-1,2-diols and alkan-m,n-diols were determined at 298.15 K by flow microcalorimetry. The pair-wise cross interaction coefficients of the virial expansion of the excess enthalpies were evaluated: they are positive and depend in a complex manner on the length of the alkyl chain of the alkanols. The behaviour of these systems is interpreted in terms of preferential interactions between the hydrophilic groups of the alkanols and the destructured domain present on glucose.

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the global optimum (D less than 1) is also changed. This paper presents for the first time a new way of using the Deringer function of desirable responses where the global optimum is examined in integer values of critical factors. Hydrophilic

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Abstract  

Formation and characterization of hydrogel of a hydrophilic polymer in a wide range of gamma absorbed doses is reported. An aqueous solution contains 2% polyvinyl alcohol (PVA) by mass irradiated under gamma rays of 60Co was chosen for study. The hydrogel was synthesized without using any additives. It was found that gel fraction is an exponential saturation function that increases with an increase of absorbed dose while swelling ratio is an exponential saturation function that decreases with an increase of absorbed dose. The results are described by energy transfer model.

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The chromatographic behavior of twelve neutral, mixed cobalt(III) complexes of the uns-cis -edda-type has been investigated in six planar chromatographic systems. Four different stationary phases - unmodified silica gel, CN-silica, cellulose, and alumina - were combined with water-organic solvent (methanol or acetone) binary mobile phases. The effect of the water content of the mobile phases on retention of the complexes was investigation systematically. On the basis of the results obtained, possible separation mechanisms were considered. Hydrophilic-interaction chromatography was assumed to be the mechanism determining separation under normal-phase conditions, i.e. use of mobile phases containing small amounts of water. Reversed-phase chromatography occurs when water-rich mobile phases are used.

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A reliable, sensitive and rapid method for determination of nicotine and three minor alkaloids (cotinine, anabasine and nornicotine) in tobacco by ultra-high performance liquid chromatography in hydrophilic interaction chromatography mode coupled with tandem mass spectrometry (HILIC-MS/MS) has been established. HILIC separation was performed on a BEH HILIC column using isocratic elution at 0.5 mL/min with acetonitrile:water (85:15, v/v) mobile phase containing 5 mmol/L ammonium acetate (pH 5.00). Separated analytes were determined by electrospray ionization MS/MS in the positive ion mode using multiple reaction monitoring. Alkaloids from tobacco were extracted in an ultrasonic bath for 10 min with acetonitrile:water mixture (8:2, v/v) containing 5 mmol/L ammonium acetate (pH 5.00). Limits of quantification were 10 μg/g for cotinine, 20 μg/g for anabasine and nornicotine, and 30 μg/g for nicotine. Mean recoveries from tobacco ranged between 94.8% and 104.1% for different analytes with relative standard deviations within 5%. The performance of the proposed method was tested for the extraction and determination of the four alkaloids in cigarette tobacco fillers, and satisfactory results were achieved.

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Epidemiological studies associated consumption of whole-durum wheat products with reduced incidence of chronic diseases, diabetes and cancer. These health benefits have been mainly attributed to antioxidant activity (AA) due to the unique phytochemical content of wheat. Milling, extrusion and drying process can influence the activity of these beneficial compounds. In order to have a deep insight into the changes of nutritional value from raw material to pasta, the aim of this study was: i) to compare the AA of hydrophilic and lipophilic extracts of five durum wheat genotypes along the pasta chain; ii) to evaluate the changes in antioxidant properties of whole meal after processing in semolina and pasta. To this aim TEAC (Trolox Equivalent Antioxidant Capacity) assay based on ABTS•+ [2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) scavenging activity was used due to its high reproducibility and simplicity.Low genotype variability was observed for both hydrophilic and lipophilic extracts. Milling process caused a significant decrease in AA due to the removal of the outside layers of the kernel. This decrease was more marked for lipophilic extracts due to the different distribution of hydrophilic and lipophilic antioxidants along the kernel. Pasta making process while determining a further decrease in AA of lipophilic extracts caused a slight increase in AA of hydrophilic extracts compared to semolina. This might be due to melanoidins formed during Maillard reaction.Only for lipophilic extracts a predictive evaluation of semolina and pasta ABTS•+ scavenging activity was possible by testing raw material.

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