Enhancement of Critical Current across Single Grain Boundaries in   YBa2Cu3Ox and Search for Superconductivity in Alkali Metals
  The ability of single grain boundaries in YBa2Cu3Ox bicrystalline rings to carry electrical current is found to be significantly enhanced under hydrostatic pressure. Nearly hydrostatic pressures are applied to the alkali metals Li, Na, and K. in a search for superconductivity. Whereas Li becomes superconducting above 20 GPa at temperatures as high as 15 K, no superconductivity was observed above 4 K in Na to 65 GPa nor in K above 4 K to 43.5 GPa or above 1.5 K to 35 GPa. 
T. Tomita, S. Deemyad, J.J. Hamlin, J.S. Schilling, V.G. Tissen, B.W.   Veal, L. Chen, H. Claus