1. Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA
2. Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
3. Bredesen Center for Interdisciplinary Research, University of Tennessee, Knoxville, Tennessee 37996, USA
4. Department of Mathematics, University of British Columbia, Vancouver, British Columbia V6T 1Z2, Canada
5. Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada