  Generalization of a disordered metal's theory has been proposed when
scattering of quasiparticles by impurities is caused with a retarded
interaction. It was shown that in this case Anderson's theorem was violated in
the sense that embedding of the impurities in s-wave superconductor increases
its critical temperature. The increasing depends on parameters of the metal,
impurities and their concentration. At a specific relation between the
parameters the critical temperature of the dirty superconductor can essentially
exceed critical temperature of pure one up to room temperature. Thus the
impurities catalyze superconductivity in an originally low-temperature
superconductor.
