Universal behavior of dispersion forces between two dielectric plates in   the low-temperature limit
  The universal analytic expressions in the limit of low temperatures (short separations) are obtained for the free energy, entropy and pressure between the two parallel plates made of any dielectric. The analytical proof of the Nernst heat theorem in the case of dispersion forces acting between dielectrics is provided. This permitted us to formulate the stringent thermodynamical requirement that must be satisfied in all models used in the Casimir physics. 
G. L. Klimchitskaya, B. Geyer and V. M. Mostepanenko