Biophysics and soft condensed matter

Pseudo-Casimir force in the paranematic phase was calculated. It was shown that the range of this force coincides with the range of the mean field force, and that it is repulsive which was not noted previously. On the basis of the theory of polymer nematics we derived the equation of state for high density DNA, i.e. for the phase in between the crystal phase and the isotropic solution. Furthermore, we developed a theory for the renormalization of the elastic constant of the polymer chain with long range attractive interaction between its monomers. At high enough value of the interaction constant the theory predicts the condensation of a polymer into a toroid shape, in accord with experimental observations. Shapes of axially strained phospholipid vesicles were calculated and their stability determined. A theoretical model was developed that describes the observed difference in pH between the inner and outer solution of hollow polyelectrolyte capsules of few micrones in diameter. A phenomenological model of achiral smectics that are the new kind of polar liquid crystals was proposed which predicts three stable phases in such systems.