"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. \"Nd\" means the element \"neodymium\" and \"151Nd\" is the isotope \"neodymium-151\" with a half-life of 8.61e-03 days."@en . "1" . "surface_radioactivity_content_of_151Nd"@en . . "false" . . "2018-02-12 16:53:18.0" . . "SDN:P07::1WRX8EPL" . . "" . . "1" . "accepted"@en . "2018-02-12 16:53:18.0" . "SDN:P07::1WRX8EPL" . "SDN:P07::1WRX8EPL" . .