Fig. 10
Example of a typical diffusion curve (squares) and flux curve (stars), with the linear regression of the steady state part of the diffusion curve (full line) and of the flux curve (dashed line). The linear regression (solid line) represents the fit of the steady state part of the cumulative activity curve (constant flux, dashed line). The intercept a and the slope b of the linear regression gives the porosity εa and effective diffusivity De, respectively (see Eqs. 2, 3).