"" . "accepted"@en . "surface_radioactivity_content_of_252Cf"@en . "1" . "SDN:P07::0P3VPY5U" . "1" . . "2018-02-12 16:53:18.0" . . . . . "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. \"Cf\" means the element \"californium\" and \"252Cf\" is the isotope \"californium-252\" with a half-life of 9.68e+02 days."@en . "2018-02-12 16:53:18.0" . . "SDN:P07::0P3VPY5U" . "false" . "SDN:P07::0P3VPY5U" .