Modified Fick model

Modified Fick model, also known as mixed diffusion approach is the simplest of all approaches. It is easy to program and is less computationally expensive. In this method an equivalent Fickian diffusion coefficient is derived by considering the mixture diffusion coefficient Dktn acting in series with Knudsen diffusion coefficient Dkn as follows... 

The diffusional transport model for systems in which sorbed molecules can be divided in two populations, one formed by completely immobilized molecules and the other by molecules free to diffuse, has been developed by Vieth and Sladek 33) in a modified form of the Fick s second law. However, if linear isotherms are experimentally found, as in the case of the DGEBA-TETA system in Fig. 4, the diffusion of the penetrant may be described by the classical diffusion law with constant value of the effective diffusion coefficient,... 

The diffusion model assumes that (1) Fick s law is valid as modified by reactions (2) reactant concentrations are interpreted as probability densities (3) specific rates correspond to otherwise homogeneous reactions—Monchick et al. (1957) show that this implies neglect of interparticle correlation, which is... 

Relative recovery can be mathematically expressed by Fick s law of diffusion as modified by Jacobson (Jacobson et al., 1985). In this relationship, recovery is the ratio of the concentration in the perfusate to the concentration extracellular. For the mass recovery, an expression similar to a Michaelis-Menten formula for enzymatic reactions was derived (Ekblom et al., 1992). A number of other mathematical models for quantitative microdialysis have been proposed and are reviewed elsewhere (Justice 1993 Kehr, 1993b). 

---