At least in the sterns studied, errors of less than a factor of two are found between the total and partial immobilization cases. In contrast the diffusion constants obtained by the simple time lag equation [Eq. (6)] are as small as one ei th of those estimated for the Henry s law mode diffiisivity using the completly immobilized model (F = 0) in some cases. This means that actual errors of iqj to four fold in estimation of the true Henry s law mode diffiisivity, Dp, can possibly be introduced by use of the simple time lag technique for assy polymers if one faQs to acccaint for the effect of immobilization. [Pg.78]

Restricted diffusion. The model presented in this case study works in semiinfinite or infinite space, that is, when a sufficiently wide space is left for the transfer which never meets a limit, at least in one direction of expansion of the diffusion layer. When a limit is encountered, the fixed concentration cannot stay constant and the model does not apply anymore. In Figure 10.10, the fixed concentration at distance is zero as long as the diffusion layer does not reach the other side. [Pg.472]

Some details of the Randles circuit require further study. First, the double layer capacitance is in many cases more properly modeled with a constant phase element. This gives information on the mesoscopic structure of the oxide-electrolyte interface. Also, in some cases, the diffusion impedance contains a power-law behavior. The reason for this is controversial is it due to the back contact or rather an indicator of an unknown kinetic process in WO3 It should also be mentioned that the adsorption process proposed by Fianceschetti and Macdonald [1982] has not been studied in detail, and the systematic equivalent circuit approach of Janmik [2003] has only been rarely used. [Pg.324]

To address these questions, we follow a simplified spherical macroion that is allowed to move concomitantly with lipid diffusion. To do so, we extend our model to include protein diffusion and performed CH-DMC (see Section 2.4) calculations. We studied the same mixed membranes considered in Figure 4, focusing on two typical cases. In the first, the model protein has a diffusion constant much larger than that of lipids in the unperturbed (bare) membrane, with a ratio D = 10 between the two, while in the second, the diffusion constant is comparable to that of the lipids, and D = 2 (see Eq. 10). As we show, these two scenarios lead to different lipid and protein diffusion characteristics. [Pg.254]

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