Atransdermal patch is designed to deliver fgf-2 to surrounding tissue. the material is designed specifically to provide a stable surface concentration for a long period of time until the patch is removed. a. previous experiments have indicated a diffusivity of 5*10-8cm2/s. if this is a semi-infinite geometry, what does the surface concentration (in ug/ml) need to be in order to bring the concentration at the capillary bed depth of 400 μm to a concentration of 5μg/ml at 10 hours. assume the initial concentration in the tissue is 0 μg/ml. b. an in vitro experiment has indicated the concentration profile to be unexpected. concentration was measured with a tissue phantom over time for three different tissue formulations (replicate 1-3). what is the new expected diffusivity?