The smallest diameter carbon nanotubes yet have been discovered by a collaboration of researchers from Japan and Germany. At 3 angstroms across, the tubes are smaller than previously believed possible from some theoretical calculations. The researchers found the nanotubes at the center of multi-walled carbon nanotubes formed in a hydrogen arc discharge, and produced images of them with high-resolution transmission electron microscopy. According to the researchers' calculations, the record-setting nanotubes are likely capped at each end by cages formed of twelve carbon atoms. Prior to the recent discovery, 4 angstrom carbon nanotubes capped with twenty-atom cages were generally thought to be the smallest diameter configuration to be stable.

2) Superlensing in Liquid Waves
Physical Review E (March)
X. Hu et al.
http://link.aps.org/abstract/PRE/v69/e030201

Negative refraction, in which waves bend opposite to the usual direction as they pass from one medium to another, attracted a lot of attention when it was demonstrated for electromagnetic waves in so-called left handed materials. The effect has now been observed in liquid surface waves. The authors of this paper placed an array of copper cylinders in a tank of liquid. A source generated waves on one side of the cylinders, and the researchers observed the pattern of waves on the opposite side. At certain wave frequencies, negative refraction caused the waves to form an image of the source on the far side of the cylinders. In addition to observing this "superlensing" effect, the researchers found a band gap, a range of frequencies of waves that won't propagate through the cylinders
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Contact: James Riordon
riordon@aps.org
301-209-3238
American Physical Society
5-Apr-2004