1. Department of Mechanical Engineering University of Minnesota Twin Cities, 111 Church Street S.E. Minneapolis MN 55455 USA
2. Department of Chemical Engineering and Material Science University of Minnesota Twin Cities, 421 Washington Ave. S.E. Minneapolis MN 55455 USA
3. School of Mechanical Engineering and the Birck Nanotechnology Center Purdue University West Lafayette IN 47907 USA
4. Materials Science Division Argonne National Laboratory Argonne IL 60439 USA
5. Departamento de Fisica de Materiales & Instituto Pluridisciplinar Universidad Complutense de Madrid Madrid 28040 Spain