You think it's hard keeping your tube socks organized? Try sorting carbon nanotubes, those remarkable molecules whose electrical properties make them potential building blocks for everything from ultrasensitive diagnostic devices to transistors 100 times smaller than those in today's fastest microchips. Trouble is, when nanotubes are fabricated, they're a mixed bag; some are electricity conductors, while others are semiconductors. Since a number of practical electronics applications demand nanotubes of uniform conductivity, sorting technologies are needed.

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