Abstract
Starting from the non-equilibrium thermodynamics, the extended Clausius-Clapeyron equation for the gel-to-fluid first-order melting transition of the lipid bilayer is derived. The new equation includes the rate of increase in the transition temperatures with increasing pressure, dT/dP, as well as the rate of increase in the transition temperature with decreasing order parameter, -dT/d . The derived equation is applied to some data taken from the literature. A brief discussion of the results is given. The possible course of the mechanical relaxation in the lipid bilayer is also presented.