We have studied the controlled drug delivery problem in hemispherical plant matrix in Homework 4. We want to analyze this process for alternative matrix shapes: a slab of thickness 2L (Flg. 1 ), and a sphere of radius R (Fig. 2). The shaded area is the solid dispersion and other regions are solution. The position of the solution-dispersion interface is f(t)(f(0)=0). The drug concentration in the dispersion is CS, the aqueous concentration at the lnterface is C0 and the effective diffusivity of the drug through the water-filled part of the matrix is D. It is assumed that the concentrations at x=0 and r=R are negligible and C0/Cs&1. [15pt] (a) find the lifetime and the rate of drug release (mol/s) as a function of time of the siab shape [15pt] (b) find the lifetime and the rate of drug release (mol/s) as a function of time of the spherical device. shape device