1. We gratefully acknowledge funding from the US Office of Naval Research under Grant No. N00014-11-1-0886. Work at the Molecular Foundry at Lawrence Berkeley National Laboratory was supported by the U.S. Department of Energy under Contract # DE-AC02-05CH11231.
2. Bryskin B. D. Proceedings of the Ninth Symposium on Space Nuclear Power Systems. 246 (1992), p. 278.
3. Twin boundary interactions with grain boundaries investigated in pure rhenium