Oscillations in Carbon Nanotube Conductivity: Theoretical studies have suggested that protons can be conducted rapidly in water trapped inside carbon nanotubes. C. Y. Lee et al. (p. 1320 ) connected two aqueous reservoirs with opened, single-walled carbon nanotubes, half a millimeter long but only 1.5 nanometers wide, and observed a high, stable proton current under electroosmotic conditions arising from a single nanotube. The addition of alkali cations caused random pore blocking and oscillations in ion current, resembling events seen in biological ion channels.