Temperature and strain-rate effects on the deformation behaviors of nano-crystalline graphene sheets Zhi Yang, Yuhong Huang, Fei Ma, Yunjin Sun, Kewei Xu and Paul K. Chu Eur. Phys. J. B, 88 5 (2015) 135 Published online: 27 May 2015 DOI: 10.1140/epjb/e2015-50850-x