Reflectivity change adsorption equilibrium

EQUILIBRIUM SORPTION VALUES. The equilibrium sorption values for the extracts at various pressures of benzene are shown in Table II. The results show that O-methylated extract sorbs the most benzene at the lower pressure and that the O-octylated extract sorbs the least. At the higher pressme, the order is reversed. We believe the data shown in Table II reflect changes in the relative amounts of adsorption and absorption (swelling) with increasing size of the added alkyl groups. This interpretation is based on surface area and solubility measurements described below. 

This form of the Gibbs fundamental equation demonstrates the importance of surface and interfacial tension measurements of interfacial layers out of the adsorption equilibrium. These methods are the most frequently used techniques to follow the time-dependence of the adsorption process. However, for very slow processes, which occurs in systems with extremely small amounts of surfactants, other methods such as the radio-tracer technique and ellipsometry, or the very recently developed technique of neutron reflectivity, can be used to directly follow the change of surface concentration with time. 

It is likely that experimentally found values of molecular cross-sectional areas do not correspond to the equilibrium states of the protein layers but reflect only the transition state configuration, as assumed by MacRitchie [16] and depicted in Fig. 1. The problem of adsorption reversibility is basic for understanding the protein behavior at interfaces. The belief in the protein adsorption irreversibility is mainly based on drastic conformational changes in interfacial film and the great difficulty of desorbing a protein from this film [15], However, these criteria are not always a proof of irreversibility. It was shown in many cases [3,24,39-41] that proteins can be desorbed... 

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