Subnanometer-Diameter Wires Isolated in a Polymer Matrix by Fast Polymerization

The preparation and analysis of inorganic-organic polymer nanocomposites consisting of inorganic nanowires and multiwire "cables" in a random-coil organic polymer host is reported. Dissolution of inorganic (LiMo3Se3)n wires in a strongly coordinating monomer, vinylene carbonate, and the use of a rapid polymerization in the presence of a cross-linking agent produce nanocomposites without phase separation. Polymerization of dilute solutions yields a material containing mostly (Mo3Se3(-))n mono- and biwires, 6 to 20 angstroms in diameter and 50 to 100 nanometers long. Polymerization of more concentrated liquid crystalline solutions yields a nanocomposite containing oriented multiwire cables, 20 to 40 angstroms in diameter and up to 1500 nanometers long, that display optical anisotropy and electrical conductivity.     

Gold-198 Wires Used To Study Movements of Small Mammals

Eastern harvest mice, Reithrodontomys humulis humulis (Audubon and Bachman), were tagged with subcutaneously inserted 20 gauge gold-198 wires 10 mm long and varying in activity from 0.7 to 4.5 mc. None of the tags inserted by this method were lost or had any apparent effect on the animals. The movements of the tagged mice were successfully traced with a portable Geiger counter.     

CHEMICAL PHYSICS: Magnetic Wires Promise Giant Step for Memory

On page 2126, researchers describe a potentially cheap and simple method of creating porous plastic templates capable of molding magnetic posts so small and close together that 10(12) of them fit in a square centimeter. If each post could be addressed individually, disk drives would be able to store a terabit of data per square centimeter, a 300-fold improvement over current models.     

Conduction of ultracold fermions through a mesoscopic channel

In a mesoscopic conductor, electric resistance is detected even if the device is defect-free. We engineered and studied a cold-atom analog of a mesoscopic conductor. It consists of a narrow channel connecting two macroscopic reservoirs of fermions that can be switched from ballistic to diffusive. We induced a current through the channel and found ohmic conduction, even when the channel is ballistic. We measured in situ the density variations resulting from the presence of a current and observed that density remains uniform and constant inside the ballistic channel. In contrast, for the diffusive case with disorder, we observed a density gradient extending through the channel. Our approach opens the way toward quantum simulation of mesoscopic devices with quantum gases.