Detection of phase transitions and cooperative interactions by Avrami analysis of sigmoid biological time curves for muscle, nerve, growth, firefly, and infrared phosphorescence of green leaves, melanin, and cytochrome C.

A simple graphical analysis of sigmoid biological time curves for K+ leakage from muscle and nerve, for muscle tension and myosin ATPase, for animal, plant and bacterial growth, for firefly light flash, and for 3 micron infrared phosphorescence from green leaves, melanin, and cytochrome c shows good curve fits to the Avrami equation for phase transition kinetics. The congruences imply that the analyzed processes are rate-limited by cooperative interactions and phase transitions. That implication is strengthened and its potential usefulness enhanced by the finding that the Avrami exponents of the above biological processes are not randomly distributed but cluster about certain values indicating (in the context of the Avrami theory) whether the spread of the new phase from nuclei within the old phase occurs in one, two, or three dimensions. The implication is further strengthened by the finding that similar types of biological processes show similar values of the Avrami exponent.