Molecular computer graphic showing the crystal structure of one of the new generation of high- temperature superconductors - yttrium-barium- copper oxide (Y-Ba2-Cu3-O7-x). Discovered in 1987, the new superconducting ceramic materials are expected to lead to a technological revolution, & are the subject of intensive worldwide research. The picture highlights the square-pyramidal (red) and square-planar (green) coordination of copper by oxygen ions in this orthorhombic structure. Copper atoms are white. Yttrium ions are the yellow spheres, and barium ions the blue spheres. (Further information in Nature, 28 May 1987, page 310).