The concentration of carbon at 1 mm into the surface of the titanium slab is 0.25 kg/m3 and at 3 mm the concentration is 0.68 kg/m3. The temperature of the carburizing environment is 925 degrees Celsius, and the rate at which carbon is entering this 2 mm thick region is 1.27 x 10-9 kg/(m2s). What is the diffusion coefficient for this particular treatment?