A sustained-release system for Dramamine (an anti-nausea drug) is designed along the following lines (see figure). The drug is dissolved in a thin gelatin film with thickness L = 1 mm, and applied as a patch to the skin. The gelatin is sandwiched between two very thin polymeric membranes that offer no resistance to the passage of the drug. The drug is not volatile, so it does not transfer to the air. The diffusivity of Dramamine in the gelatin is 3 10-7 cm/s. thin polymer membranes L air gelatin (B) + dramamine (A) skin (a) Estimate the time required for 90% of the drug to be delivered (tf). Assume that the Dramamine is transported from the skin layer to the rest of the body so fast that the concentration of Dramamine in the skin is negligible at all times. (b) If the initial concentration of Dramamine in the gelatin is CAO = 0.2 g/cm, and the patch has a surface 4 cm x 4 cm, calculate the instantaneous mass flow rate of Dramamine (g/s) that is delivered to the body at times t= tf/2 and t= tf.