X-ray Irradiation Induced Reversible Resistance Change in Pt/TiO2/Pt Cells, S. H. Chang, J. Kim*, C. Phatak, K. D’Aquila, S. K. Kim, J. Kim, S. J. Song, C. S. Hwang, J. A. Eastman, J. W. Freeland, andS. Hong*, ACS Nano 8, 1584 - 1589 (2014)