"2018-02-12 16:53:18.0" . "SDN:P07::2UWOLA6D" . "" . "false" . . "SDN:P07::2UWOLA6D" . "1" . "accepted"@en . . . "1" . "2018-02-12 16:53:18.0" . . . "\"Radioactivity\" means the number of radioactive decays of a material per second. \"Radioactivity concentration\" means radioactivity per unit volume of the medium. \"Cf\" means the element \"californium\" and \"251Cf\" is the isotope \"californium-251\" with a half-life of 2.92e+05 days."@en . . "radioactivity_concentration_of_251Cf_in_air"@en . "SDN:P07::2UWOLA6D" .