"The surface called \"surface\" means the lower boundary of the atmosphere. \"Content\" indicates a quantity per unit area. \"Radioactivity\" means the number of radioactive decays of a material per second. \"Ag\" means the element \"silver\" and \"109mAg\" is the metastable state of the isotope \"silver-109\" with a half-life of 4.58e-04 days."@en . "2018-02-12 16:53:18.0" . . . "SDN:P07::5HV8F33O" . "1" . "surface_radioactivity_content_of_109mAg"@en . "SDN:P07::5HV8F33O" . . "1" . . "SDN:P07::5HV8F33O" . "2018-02-12 16:53:18.0" . "" . . "false" . . "accepted"@en .