Browsing by Author "Pethig, Ronald"

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    Dielectric Properties of Hydrated Proteins at 9.9 GHz
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (10), 1977) Bone, Stephen; Gascoyne, Peter R. C.; Pethig, Ronald
    The complex dielectric permittivities of bovine serum albumin, cytochrome-c and lysozyme powders have been measured as a function of partial hydration at 9.9 GHz using a microwave cavity perturbation technique. By analysing the results in terms of multilayer sorption it is concluded that only water bound to these proteins in the secondary hydration layers is able to contribute significantly to dielectric loss at this frequency. Such measurements are of relevance regarding the development of microwave techniques for the treatment or detection of cancerous tissue.
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    Experimental and theoretical aspects of hydration isotherms for biomolecules
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (1), 1977) Gascoyne, Peter R. C; Pethig, Ronald
    A resonating quartz crystal microbalance technique has been used to obtain room temperature water sorption isotherms for cytochrome-c, DNA, lecithin, lysozyme and serum albumin. The results compare favourably with earlier work using more conventional techniques. A completely general formula describing the sorption isotherms is derived. With the assumption of identical and non-interacting primary sorption sites, this general formula gives exact values for the monolayer site capacity and the thermodynamic activities of all the hydration states. However, it is shown that at least one of these assumptions is not valid for the materials studied here, accordingly only limited information can be derived using this theory. This restricted usefulness also applies to other sorption theories described in the literature, most of which are based on purely modelistic or kinetic considerations. The significance of a sorption activity parameter having values greater or less than unity is discussed for the materials examined.