Contents

23 February 1996
Vol 271, Issue 5252

About The Cover

Representation of a hexameric assembly of dendrimers (hyperbranched polymers, shown with four layers or generations). Hydrogen-bonding contacts at the core of each dendrimer and peripheral van der Waals interactions stabilize the assembly, whose size rivals that of a small protein. White, hydrogen; black, carbon; red, oxygen; and blue, nitrogen. See 1095 and the Perspective on 1077. [Image created by Paul A. Thiessen with PovChem (see http://ludwig.scs.uiuc.edu) on a Silicon Graphics Indigo]