1. Theoretical and Applied Mechanics Program Northwestern University 2145 Sheridan Rd. Evanston IL 60208 USA
2. Department of Materials Science and NanoEngineering Rice University 6100 Main Street Houston TX 77005 USA
3. Center for Nanoscale Materials Argonne National Laboratory Lemont IL 60439 USA
4. Department of Mechanical Engineering Northwestern University 2145 Sheridan Rd. Evanston IL 60208 USA