Where k is the Boltzmann constant, T is the temperature (K), and m is the mass of the molecule. If we assume the mass of the molecule as 200 g•mol -1 and a temperature of 37 °C, we get a velocity of 6000 m•s -1 , which can be considered as a gas permeability limit (logPerm = +5.8 log units of cm•s -1 ) but only in the case of a negligible thickness of the membrane, area of permeation equal to the projection is of the molecule itself and maximum possible concentration difference. This value is purely hypothetical and does not correspond to the biomembrane permeability in real liquid conditions. It is only stated here as the absolute upper limit of the permeability. Even the 60 times smaller value of permeability (logPerm = +4 log units of cm•s -1 ) is still purely hypothetical and impossible to get in biomembrane permeation; thus, this limit is used in graphs and discussion below due to the 4 orders of magnitude difference between all other limits.