1. Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
2. Department of Mechanical Engineering, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
3. X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
4. Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA