The behavior of thermodynamic properties at critical endpoints is discussed and the first results of studies underway (in collaboration with P.J. Upton and with M.C. Barbosa) are sketched. New universal aspects, beyond normal bulk criticality, appear in singularities of the phase boundary to the “spectator phase” and in the surface tensions of the corresponding noncritical interfaces. Mean field theory and more general local free energy functionals can be applied. Some quantitative estimates are presented for universal surface tension amplitude ratios for two distinct classes of endpoint: symmetric and nonsymmetric. A promising parametric “trigonometric model” for the scaled equation of state is mentioned and other approaches are touched upon.
