In 1999, Kim and Lieber attached these entities to two independent electrodes to prepare the first near-atomic electromechanical system, which operated like a tweezer. Vertically aligned arrays of these entities are often generated using a “tip-growth” or “base-growth” methodology. Another of these entities can be produced in a reaction involving a metal carbonyl catalyst at high pressure called the HiPCO (“hip-COE”) method. The perimeter vector of these structures is commonly represented using (*) (m,n) (“m-comma-n”) lattice index notation. Depending on how they fold onto themselves, these structures can assume chiral, armchair, or zigzag configurations. In the Russian-doll model, (10[1])multi-walled examples of these structures comprise many concentric graphene layers. For 10 points, (10[1])name these cylindrical allotropes (10[1])of carbon. ■END■ (10[1]0[1])