1. Department of Mechanical Engineering and Multidisciplinary Program in Materials Science and Engineering, State University of New York, Binghamton, New York 13902, USA
2. Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
3. Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA and Department of Physics, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA