7.37 A thin cylindrical disk of genetically transformed hepatocytes 2.5cm in diameter is suspended in a nutrient solution at 37°C. The nutrient solution has a density of 1 g cm−3 and a viscosity of 0.0012 Pa s. The oxygen diffusivity in the nutrient solution was found to be 2.5 × 10−5 cm2 s−1. The half-thickness of the disk (δ) that contains the cells is 150 μm, and the cell fraction is 0.35. The consumption rate of oxygen on a per cell volume basis by these cells is 18.5 μM s−1. If the pO2 of oxygen in the bulk nutrient solution is 150 mmHg, estimate the RPM that the disk needs to be rotated at so that the oxygen level at the centerline of the disk (i. e., at x = δ) is at least 25 mmHg. Assume Henry’s constant for the oxygen in this nutrient solution is equal to 0.73 mmHg μM−1.