Nanotube water

Nanotube water, a quasi-one-dimensional form of water consisting of a string of water molecules threading an ice sheath within a single-walled carbon nanotube (SWNT), has been studied by physicists at Argonne National Laboratory. Neutron scattering measurements, along with computer simulations of the molecular interactions between the water and the surrounding SWNT, confirmed that water molecules first formed an ice lining inside the tube. A chain of water molecules then filled the remaining volume and exhibited fluidlike behavior at temperatures far below the normal freezing point. The hydrogen bonds along the water chain seem to be softened, allowing, for example, a freer movement of protons through the tube. The Argonne researchers say that this anomalous behavior might help to explain other phenomena that feature nanometer-scale confined water. Such phenomena include water migration from soil to plants via xylem and proton translocation in transmembrane proteins. (A. I. Kolesnikov et al., Phys. Rev. Lett. 93, 035503, 2004 http://dx.doi.org/10.1103/PhysRevLett.93.035503 .)