Semi-infinite: a transdermal 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?

Acommercial grade cubical freezer, 4 m on a side, has a composite wall consisting of an exterior sheet of 5.0-mm thick plain carbon steel (kst= 60.5 w/m k), an intermediate layer of 100-mm thick polyurethane insulation (kins 0.02 w/m k), and an inner sheet of 5.0- mm thick aluminium alloy (kal polyurethane insulation and both metallic sheets are each characterized by a thermal contact resistance of r 2.5 x 104 m2 k/w. (a) what is the steady-state cooling load that must be maintained by the refrigerator under conditions for which the outer and inner surface temperatures are 25°c and -5°c, respectively? (b) for power saving purpose, which wall material should be increased/reduced in. thickness in order to reduce 50% of the cooling load found in part (a)? redesign the thickness of the proposed material. 177 w/m-k). adhesive interfaces between the q=575.93 w