"SDN:P07::57Z6N9NC" . "SDN:P07::57Z6N9NC" . "false" . . . . "" . "2018-02-12 16:53:18.0" . "SDN:P07::57Z6N9NC" . "\"Radioactivity\" means the number of radioactive decays of a material per second. \"Radioactivity concentration\" means radioactivity per unit volume of the medium. \"U\" means the element \"uranium\" and \"234U\" is the isotope \"uranium-234\" with a half-life of 9.02e+07 days."@en . "1" . . "accepted"@en . "radioactivity_concentration_of_234U_in_air"@en . "2018-02-12 16:53:18.0" . . "1" . .