he immobilized enzyme layer shown in the figurebelow is designed to convert substrate A to product B accordingto the simplified reaction A B with simplified rate equationRA k cA$.$ In this process, the steady$-$state concentrations ofsubstrate A in the bulk liquid and the interface between theenzyme layer and its inert support surface were measured, withcA $1\mathrm{.}0$ mmol$/$m$3$ at z $0,$ and cAL $0\mathrm{.}25$ mmol$/$m$3$ at z L$.$The effective diffusion coefficient of substrate A within theenzyme layer is DAe $2\mathrm{.}0105$ cm$2/$s$,$ and the thicknessof the immobilized enzyme layer is L $0\mathrm{.}2$ cm$.$ The surroundingfluid is well mixed, and the concentration of substrate A at thesurface of the enzyme layer can be taken as the bulk concentra$-$tion of substrate A in the surrounding liquid.