“…Equation (4) produces a good approximation s m for s under certain conditions (sometimes called validity criteria) [3], [5], [11], [12], [18], [28], [24], [25]. Thus, the condition e 0 s 0 assures good approximation and is ubiquitous for many fermentation and biotechnological processes, but may not be present, as in living cells [1], [26].…”