Double-walled carbon nanocones: stability and electronic structure Elias Brito, Aliliane Freitas, Thiago Silva, Thiago Guerra and Sergio Azevedo Eur. Phys. J. B, 88 6 (2015) 153 Published online: 10 June 2015 DOI: 10.1140/epjb/e2015-60159-5