Growth and Characterization of New Semi-Organic L-AsparaginePotassium Di-Hydrogen Phosphate Crystals

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Hydration properties of Na, K, Mg gluconates and gluconate/sucrose mixtures and their possible taste effect

International audienceDensity and ultrasonic velocity were measured in aqueous solutions of sodium, potassium and magnesium gluconate as a function of increasing concentration. Apparent molar volume (AMV), apparent specific volume (ASV), isentropic apparent molar (IAMC) compressibility and hydration numbers were calculated from the experimental data. The results show that AMV and ASV increase as the concentration of gluconates is increased. This is interpreted on the basis of molecular interaction between solute and solvent molecules. These measurements were repeated by adding Na, K and Mg gluconates to 10 and 20% sucrose solution with the aim of understanding the influence of gluconates on water association in sucrose solutions. The results show that the values of IAMC decrease as the concentration is increased. Moreover, Mg gluconate shows more negative IAMC than Na and K gluconates. The observed results are explained on the basis of the hydration of gluconates in the sucrose-water system. NMR relaxation rates (R1 and R2) show an increase as the concentration of the gluconate is increased. On the other hand, the results of Na, K and Mg gluconate in 10 and 20% sucrose solutions demonstrated that the effect of Mg gluconate enhances the hydration properties of sucrose water mixtures more than Na and K gluconate. The overall results show the importance of water interactions with sapid molecules and this can lead to a better understanding of their tastes

Hydration Properties and the Role of Water in Taste Modalities of Sucrose, Caffeine, and Sucrose−Caffeine Mixtures

International audienceSolution properties of sapid molecules are informative on their type of hydration (hydrophobic or hydrophilic) and on the extent of the hydration layer. Physicochemical properties (intrinsic viscosity and apparent specific volume) and nuclear magnetic resonance (NMR) relaxation rates R-1 and R-2 for pure sucrose, bitter molecule caffeine, and their mixture were found to be relevant in the interpretation of the effects of these solutes on water mobility. Likewise, surface tension, contact angles with a hydrophobic surface, and the adhesion forces to this type of surface of the aqueous solutions of sapid molecules were found to discriminate between their effects on water cohesion and also between their taste qualities. The interpretation of the two sets of independent experimental results, namely physicochemical and spectroscopic data, helps in the elucidation of the role of water in sweet and bitter taste chemoreception

NMR Diffusion Studies on the Binding of Hyaluronate -Methotrexate Conjugates with Bovine Serum Albumin in Aqueous Solution

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Structural and Spectral Properties of 1,2-dihydroxy-9,10-anthraquinone Dye Sensitizer for Solar Cell Applications

The geometries, electronic structures, polarizabilities, and hyperpolarizabilities of natural dye sensitizer alizarin from madder fruit was studied based on density functional theory using the hybrid functional B3LYP. Features of the electronic absorption spectra in the visible and near-UV regions were assigned based on time-dependent density function theory calculations. The calculated results suggest three excited states with the lowest excited energies in 1,2-dihydroxy-9,10-anthraquinone and it was due to photoinduced electron transfer processes. The interfacial electron transfer between semiconductor $TiO_2$ electrode and dye sensitizer 1,2-dihydroxy-9,10-anthraquinone is due to an electron injection process from excited dye to the semiconductor conduction band. The importance of hydroxyl group in geometries, electronic structures and spectral properties were reported

Structural and optical properties of Purpurin for dye-sensitized solar cells

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Hydration properties and proton exchange in aqueous sugar solutions studied by time domain nuclear magnetic resonance

Proton NMR relaxation rates (R-1 and R-2) were measured in aqueous solutions of sucrose, D-glucose and D-fructose with increasing concentration. The measurements were carried out using Bruker PC 20 NMR Process Analyzer. Inversion recovery and CPMG pulse sequences are used for the measurement of relaxation rates. Results show that the values of relaxation rate increase as the concentration of the sugar is increased. The relaxation rate appears to be higher for sucrose solutions as compared to glucose or D-fructose solutions. These results were discussed on the basis of molecular association between sugar and water molecules through hydrogen bonding. The water self diffusion coefficient was measured in these sugar solutions by using pulse field gradient NMR method. As expected, the water self-diffusion coefficient was reduced with increased sugar concentrations. The results of translational mobility exhibited a higher mobility for fructose than glucose or sucrose in aqueous solutions. The dependence of R-2 on the inter-pulse delay of the CPMG sequence gives information on the proton exchange mechanism involved. The mechanism of exchange was studied using R-2 with increasing inter pulse delay of 0.05-2.0 ms in aqueous solutions of 10%, 20% and 35% (w/v) of the above sugar solutions. From the plots of relaxation rates (R-2) versus the 90 degrees-180 degrees pulse spacing it was possible to calculate the proton exchange rate (k(b)) of the different sugar solutions. Relaxation rates show characteristic variations with CPMG pulse spacing which can be interpreted on the basis of chemical exchange between solute and solvent molecules. The experimental results namely relaxation rates and CPMG pulse spacing data show the importance of water interactions with sweet molecules and this can lead to a better understanding of the effect of hydration water in taste chemoreception. (C) 2011 Elsevier Ltd. All rights reserved

Hydration properties and proton exchange in aqueous sugar solutions studied by time domain nuclear magnetic resonance

Proton NMR relaxation rates (R1 and R2) were measured in aqueous solutions of sucrose, D-glucose and Dfructose with increasing concentration. The measurements were carried out using Bruker PC 20 NMR Process Analyzer. Inversion recovery and CPMG pulse sequences are used for the measurement of relaxation rates. Results show that the values of relaxation rate increase as the concentration of the sugar is increased. The relaxation rate appears to be higher for sucrose solutions as compared to glucose or D-fructose solutions. These results were discussed on the basis of molecular association between sugar and water molecules through hydrogen bonding. The water self diffusion coefficient was measured in these sugar solutions by using pulse field gradient NMR method. As expected, the water self-diffusion coefficient was reduced with increased sugar concentrations. The results of translational mobility exhibited a higher mobility for fructose than glucose or sucrose in aqueous solutions. The dependence of R2 on the inter-pulse delay of the CPMG sequence gives information on the proton exchange mechanism involved. The mechanism of exchange was studied using R2 with increasing inter pulse delay of 0.05\u20132.0 ms in aqueous solutions of 10%, 20% and 35% (w/v) of the above sugar solutions. From the plots of relaxation rates (R2) versus the 90\u2013180 pulse spacing it was possible to calculate the proton exchange rate (kb) of the different sugar solutions. Relaxation rates show characteristic variations with CPMG pulse spacing which can be interpreted on the basis of chemical exchange between solute and solvent molecules. The experimental results namely relaxation rates and CPMG pulse spacing data show the importance of water interactions with sweet molecules and this can lead to a better understanding of the effect of hydration water in taste chemoreception