Two independent teams have made ultrathin, cabon-based membranes with extraordinary properties that could be used in a range of applications, from water filtration to petroleum processing. One team, based at the University of Manchester in the UK, has made membrane from graphene oxided that appears to be highly permeable to water while being impermeable to all other liquids and gases. The other group, at Japan’s National Institute for Materials Science, has made membranes from diamond-like carbon (DLC) that are highly permeable to certain organic solvents, but not others.