F. J. Dominguez-Gutierrez

A tiny diamond ball is pressed into a piece of metal: that's how you test a material's hardness. But what happens inside, right under that ball? Scientists took an alloy of molybdenum, tantalum, and tungsten and looked into the thick of its atoms. The experiment was repeated in a computer, modeling millions of atoms.

A photocatalyst is a powder that, when placed in water under light, splits it into bubbles of hydrogen and oxygen. The most popular material for this is titanium dioxide, the white pigment in paints and toothpaste. But a pure crystal works sluggishly: it absorbs only ultraviolet light, and such rays are scarce in the solar spectrum.