  The buckling and twisting of slender, elastic fibers is a deep and
well-studied field. A slender elastic rod that is twisted with respect to a
fixed end will spontaneously form a loop, or hockle, to relieve the torsional
stress that builds. Further twisting results in the formation of plectonemes --
a helical excursion in the fiber that extends with additional twisting. Here we
use an idealized, micron-scale experiment to investigate the energy stored, and
subsequently released, by hockles and plectonemes as they are pulled apart, in
analogy with force spectroscopy studies of DNA and protein folding. Hysteresis
loops in the snapping and unsnapping inform the stored energy in the twisted
fiber structures.
