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[21 marks) Section 11/Question 5 (a) A section of muscular tissue is being used to evaluate the efficacy of simultaneous heat and drug treatment. The tissue can be modelled as a slab of thickness L (from x = 0 to x=L). The heat treatment imposes a temperature profile T= T. exp(-Ax), where T. and I are constants. The drug diffuses through the tissue with the end x = 0 being maintained at a concentration Co, while the end x = L is insulated to mass transport. The diffusivity of the drug varies as D = D.(TIT), where T, is a reference temperature. The drug is consumed by a zeroth-order reaction, whose rate constant is given by k = k. (TIT). Determine the concentration profile of the drug in the tissue. [9 marks] (b) Experiments are repeated in a tissue in the form of a cylindrical annulus of inner radius , and outer radius 12. The temperature varies in the cylindrical annulus as T = T. exp(-Ar) while the concentration of drug at the inner boundary is C, and that at the outer boundary is c2. The drug diffusivity varies as D = D. (r/n) (TIT.)? Exactly as before, a zeroth-order reaction occurs, with the rate as given above. Determine the concentration profile of the drug in the annulus. [12 marks] END OF QUESTION 5