The transport properties of various systems are studied here in the context of three different models.These are: - the disordered Hubbard model applicable to Semi Permanent correlated binary alloys with a general disorder, - the Anderson model used in describing the Kondo physics of a quantum dot connected to the external superconducting leads, and - the Ranninger-Robaszkiewicz model applied to the study of optical properties of the system with preformed electron pairs above the temperature of transition to the superconducting state.We calculate the density of states, specific heat, the Wilson ratio and Pants conductivity of the correlated binary alloy with off-diagonal disorder.We investigate the conditions under which the Kondo peak appears in the density of states and in the conductance of a dot coupled to the external superconducting leads.We analyze the effect of the pseudogap on the optical spectra in the high temperature superconductors described by the boson-fermion model.