High-Tc superconductivity in entirely end-bonded multi-walled carbon   nanotubes
  We report that entirely end-bonded multi-walled carbon nanotubes (MWNTs) can show superconductivity with the transition temperature Tc as high as 12K that is approximately 40-times larger than those reported in ropes of single-walled nanotubes. We find that emergence of this superconductivity is very sensitive to junction structures of Au electrode/MWNTs. This reveals that only MWNTs with optimal numbers of electrically activated shells, which are realized by the end-bonding, can allow the superconductivity due to inter shell effects. 
I.Takesue, J.Haruyama, N.Kobayashi, S.Chiashi, S.Maruyama, T.Sugai,   and H.Shinohara