where 𝐷 0 (μm 2 .s -1 ) is a pre-exponential factor, representing the diffusion coefficient at infinite temperature, 𝑄 (J.mol -1 ) is an activation energy for the diffusion, R is the gas constant (8.314 J.mol - 1 .K -1 ), and T (°C) is the temperature. In equation (i), 𝐷 0 and 𝑄 are constant and serve as fitting parameters.