One day, physicist Ho - Kei Chan of Trinity College Dublin was playing with steel ball bearings, trying to pack them into a little cylindrical tube in the most efficient way possible. (sciencemag.org)
CNTs are nanosized cylindrical tubes with high theoretical electrical conductivity. (sciencedaily.com)
Each front leg exhibits a single ear below the knee with two eardrums (also known as tympanic membranes), which are backed by a narrow cylindrical tube (the acoustic trachea) running along the leg internally and opening out on the side of the insect's body. (sciencedaily.com)