Modified Cahn model for surface tension with the presence of a contact   line applied to regular solutions
  We derive the interfacial tension of a semi infinite two phase binary mixture of partially miscible fluids in contact with a planar surface. In our model we take a surface free energy term into account omitted by Cahn [J. W. Cahn, J. Chemical Physics, 66:3667-3672,1977]. Our analysis applied to the case of regular solutions shows that this extra surface free energy term cannot a priori be neglected. 
Lionel Hirschberg and Avraham Hirschberg
physics.flu-dyn