1,028 research outputs found
Time evolution of the reaction front in a subdiffusive system
Using the quasistatic approximation, we show that in a subdiffusion--reaction
system the reaction front evolves in time according to the formula
, with being the subdiffusion parameter. The
result is derived for the system where the subdiffusion coefficients of
reactants differ from each other. It includes the case of one static reactant.
As an application of our results, we compare the time evolution of reaction
front extracted from experimental data with the theoretical formula and we find
that the transport process of organic acid particles in the tooth enamel is
subdiffusive.Comment: 18 pages, 3 figure
Hyperbolic subdiffusive impedance
We use the hyperbolic subdiffusion equation with fractional time derivatives
(the generalized Cattaneo equation) to study the transport process of
electrolytes in media where subdiffusion occurs. In this model the flux is
delayed in a non-zero time with respect to the concentration gradient. In
particular, we obtain the formula of electrochemical subdiffusive impedance of
a spatially limited sample in the limit of large and of small pulsation of the
electric field. The boundary condition at the external wall of the sample are
taken in the general form as a linear combination of subdiffusive flux and
concentration of the transported particles. We also discuss the influence of
the equation parameters (the subdiffusion parameter and the delay time) on the
Nyquist impedance plots.Comment: 10 pages, 5 figure
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