"2019-03-04 17:29:46.0" . . "2" . . . "\"Mass fraction\" is used in the construction \"mass_fraction_of_X_in_Y\", where X is a material constituent of Y. It means the ratio of the mass of X to the mass of Y (including X). A chemical or biological species denoted by X may be described by a single term such as \"nitrogen\" or a phrase such as \"nox_expressed_as_nitrogen\". The chemical formula for the hydroxyl radical is OH. In chemistry, a \"radical\" is a highly reactive, and therefore short lived,species."@en . "false" . "accepted"@en . "SDN:P07::CF12N384" . . . "SDN:P07::CF12N384" . "SDN:P07::CF12N384" . "2" . "" . "mass_fraction_of_hydroxyl_radical_in_air"@en . . . "2019-03-04 17:29:46.0" . .