Giant Strengthening of Superconducting Pairing in Metallic Nanoclusters
  The presence of shell structure and the accompanying high level degeneracy leads to a strengthening of the pairing interaction in some metallic nanoclusters and ions. It is predicted that for some specific systems one can expect a large increase in the values of the critical temperature and other parameters. 
Y.N. Ovchinnikov, V.Z.Kresin