The unique chemical signature of the stars may provide clues to what's going on. (sciencemag.org)
Because different species may leave distinct chemical signatures in the soil that could in turn affect how vegetation grew at the site, it only made sense to test the technology on humans. (discovermagazine.com)
Second, the carbon from dirty energy has a unique chemical signature that allows scientists to tell it apart from other sources of carbon. (realitydrop.org)