1. Department of Materials Science & Engineering, University of California, Berkeley, Berkeley, California 94720-7118, United States
2. National Center for Electron
Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
3. Department of Mechanical Engineering, Stony Brook University, Stony Brook, New York 11794,
United States
4. Department
of Mechanical Engineering, University of California, Berkeley, Berkeley, California
94720-7118, United States
5. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California
94720, United States