DYNAMIC LIGHT SCATTERING STUDIES OF COLLAGEN-GELATIN AND GEL.
Item
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Title
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DYNAMIC LIGHT SCATTERING STUDIES OF COLLAGEN-GELATIN AND GEL.
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Identifier
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AAI8103935
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identifier
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8103935
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Creator
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HWANG, JENN-SHYONG.
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Contributor
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Herman Z. Cummins
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Date
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1980
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Language
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English
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Publisher
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City University of New York.
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Subject
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Physics, Optics
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Abstract
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The technique of intensity correlation spectroscopy using a digital autocorrelator was employed to investigate the collagen-gelatin and gel systems. Various hydrodynamic properties were derived from the autocorrelation functions of different samples. In this thesis a general review of the previous studies and physico-chemical properties of these systems are given first, followed by a brief outline of the theory of intensity fluctuation spectroscopy and a description of the apparatus and experimental technique used in this study. The research work and results are then discussed in three separate parts, each dealing with one topic--the gelatin solutions, gelatin gels and collagen solutions.;For the extremely polydisperse gelatin solution the concentration dependence of the diffusion coefficient was investigated and a relation N (PROPORTIONAL) C('5) for the polymerization index of the aggregates and the concentration was obtained. Moderately polydisperse solutions obtained by the centrifugation of the gelatin solutions however show that the gelatin particles execute free diffusion at low concentrations and form a polymer network at high concentrations. The z-average free diffusion coefficient is independent of concentration and is proportional to q('2). The hydrodynamic radii and polydispersities of the gelatin molecules at different salt concentrations and temperatures were also studied. The results lead to the conclusion that most of the aggregates are covalently linked and the hydrogen bonded and collagen-folded aggregates do not make significant contributions at 20(DEGREES)C or higher temperatures.;Single exponential autocorrelation functions were obtained for gelatin gels with and without crosslinking agent. The elastic continuum model was found to describe all the observed properties better than the bounded diffusion model. As the concentration increases the cooperative diffusion coefficient decreases in the solution state but increases in the gel state. For gels without a crosslinking agent the decay rate of the correlation function was found to remain constant after it reached a terminal value several hours after its temperature was changed to 20(DEGREES)C. However, for gels with a crosslinking agent the decay rate continuously increased in time and the spatial correlation length became shorter with age.;Very monodisperse collagen samples were obtained through the purification of density gradient separation. Autocorrelation functions were measured at 31.8(DEGREES) and 90(DEGREES) scattering angles. The translational and rotational diffusion coefficients were calculated from the directly measured correlation functions of non-zero degree scattering. A length of 2715 (+OR-) 100(ANGSTROM) was obtained for the tropocollagen molecules and is in agreement with previous literature values.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Physics
