Today's best molecular filters, siliceous zeolites, filter gases too slowly to be of much use for everyday applications. So researchers at Carnegie Mellon University in Pittsburgh, PA, have an alternative solution: carbon nanotubes. Using atomistic simulations, David Sholl and associates calculated both self- and transport diffusivities of light gases in carbon nanotubes and in two zeolites with comparable pore sizes. The carbon nanotube filter gases 100 to 1,000 times faster than siliceous zeolites or any microporous material for which experimental data are available. This increased speed implies that nanotubes could provide a practical way to make large-scale gas filters, says Sholl. For more information, e-mail David S. Sholl at email@example.com.