FIGURE 1. High-resolution transmission electron microscopy images of carbon nanotubes in a genuine Damascus sabre after dissolution in hydrochloric acid.

a, b, Multiwalled tubes with the characteristic layer distance d 0.34 nm (ref. 12), as indicated by the Fourier transforms (see insets). Scale bars: 5 nm (a) and 10 nm (b). In b, the tubes are bent like a rope. c, Remnants of cementite nanowires encapsulated by carbon nanotubes, which prevent the wires from dissolving in acid. Scale bar, 5 nm. The fringe spacing of the wire is 0.635 nm, taken from the Fourier transform (inset), and is attributed to the (010) lattice planes of cementite.