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Measurement And Study On Diffusion Coefficient And Thermodynamic Property Of Aqueous Medicaments Solutions

Posted on:2005-05-01Degree:DoctorType:Dissertation
Country:ChinaCandidate:C W ZhaoFull Text:PDF
GTID:1101360122482274Subject:Chemical processes
Abstract/Summary:PDF Full Text Request
Amino acids are useful as models of specific aspects of more complex proteins in aqueous solution. Glucose, sucrose and L-ascorbic acid are necessary to grow in the body. There have been significant interest and value in the investigations on diffusion and thermodynamic property in aqueous solutions.Firstly, diffusion coefficients of these medicaments were investigated. A set of apparatus of holographic interferometry determining liquid diffusion coefficients was designed and established. The reliability was confirmed with literature data. Liquid diffusion coefficients of aqueous solutions of eight amino acids such as glycine were measured at 298.15K. The influences of molecular structure and polarity on liquid diffusion coefficients were also discussed. At the same time, infinite dilute liquid diffusion coefficients obtained by experimental extrapolation, were good agreement with the results based on the fundamental equation developed from statistical mechanics.In order to investigate the influence of temperature on liquid diffusion coefficients, liquid diffusion coefficients of aqueous glucose, L-ascorbic acid and L-threonine solutions were determined from 298.15K to 328.15K by metallic diaphragm cell method. A new semi-empirical model for correlating the diffusion coefficients containing temperature was provided with more comprehensive and less experiment compared to the previous model.Secondly, thermodynamic properties of aqueous some medicaments solutions were investigated. Densities and viscosities of aqueous solutions of eight amino acids such as glycine were measured as a function of amino acid concentration from 293.15K to 333.15K by an oscillating-tube densimeter and a viscositymeter. These data were used to calculate the apparent molar volumes, partial molar volumes and viscosity -coefficients. Using group contribution method the contributions of related groups of amino acids to partial molar volumes and viscosity -coefficients were obtained, the results confirmed this group additivity method had excellent predictive utility.In order to investigate refluences of solvent on thermodynamic property, densities and viscosities of L-threonine and L-arginine in glucose-water, sucrose-water and L-ascorbic acid-water mixed solvents were measured at 298.15K. Apparent molar volumes, partial molar volumes, numbers of hydration and viscosity B-coefficients of L-threonine and L-arginine were calculated and correlated. The transfer partial molar volumes from water to sugar-water or L-ascorbic acid-water mixtures and numbers of hydration were also obtained and discussed in terms of the cosphere overlap model. Furtherly, different side chain contributions of amino acids to transfer partial molar volumes were also investigated. Data obtained could provide valuable information that ultimately led to a better understanding of behavior of biological micromolecules or proteins.
Keywords/Search Tags:Amino acid, Liquid diffusion coefficient, Holographic interferometry method, Diaphragm cell method, Density, Viscosity, Group contribution method
PDF Full Text Request
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