Resistance of superconducting nanowires connected to normal metal leads
  We study experimentally the low temperature resistance of superconducting nanowires connected to normal metal reservoirs. We find that a substantial fraction of the nanowires is resistive, down to the lowest temperature measured, indicative of an intrinsic boundary resistance due to the Andreev-conversion of normal current to supercurrent. The results are successfully analyzed in terms of the kinetic equations for diffusive superconductors. 
G.R. Boogaard, A.H. Verbruggen, W. Belzig, and T.M. Klapwijk