  We identify a new material phenomenon, where minute mechanical manipulations
induce pronounced global structural reconfigurations in faceted multi-walled
nanotubes. This behavior has strong implications on the tribological properties
of these systems and may be the key to understand the enhanced inter-wall
friction recently measured for boron-nitride nanotubes with respect to their
carbon counterparts. Notably, the fast rotation of helical facets in these
systems upon coaxial sliding may serve as a nanoscale Archimedean screw for
directional transport of physisorbed molecules.
