while a chiral one grows unobstructed, DG = - Dm*N F. Ding et al., PNAS 2009 Dilemma of “chiral relativity” = C2 For (n,m) tube, m kinks serve as active sites for C accretion, Growth rate K ~ m/D ~ sin (q) ~ q, 0 < q < 30o Alternatively, relative to armchair Gr...