Nature reports that researchers at the University of Tokyo have developed a silicon, aluminum and oxygen sponge that looks (at the atomic scale) like "swiss cheese" -- and is able to absorb the smog-producing hydrocarbon emissions that catalytic converters won't catch while warming up. 80% of the hydrocarbon emissions escape during the first few minutes after a cold start. This sponge -- made of a material called SSZ-33 (they really need to work on their marketing, I suspect) -- traps the hydrocarbons until the catalytic converters are warm enough to function.