1. Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7919, USA
2. Adroit Materials, Inc., 2054 Kildaire Farm Rd., Suite 205, Cary, North Carolina 27518, USA
3. Engineering Sciences Directorate, Army Research Office, P.O. BOX 12211, Research Triangle Park, North Carolina 27703, USA