Imagine you have a membrane through which oxygen can diffuse with a diffusion coefficient D = 5x10-10 m2/s. The concentration of O2 on one side of the membrane is 5x1022 atoms/m3, and on the other side it is 3.5x1022 atoms/m3. If the membrane is 2.5x10-9 m thick, what is the diffusive flux of oxygen J?