Number 168 (Story #2), March 10, 1994 by Phillip F. Schewe and Ben Stein AEROCRYSTAL NETWORKS combine the preparation techniques used for aerogels---gel materials that are more than 90% air---with the technical promise of porous silicon---silicon that has been etched by acid into a honeycomb of light-emitting filaments. Scientists at the DRA Malvern lab in Britain use a "supercritical drying" technique to make a crystalline, columnar silicon network with a porosity in excess of 95%. The material is strongly photoluminescent, which will make it useful for optoelectronics applications. (L.T. Canham et al., Nature, 10 March 1994.)