> as lemmas

1935 Jrnl. Amer. Chem. Soc. 57 781/2 It seemed possible that radio-cesium might be an exception to the rule and emit a positron since the emission of an electron would result in the formation of Ba¹³⁴ which apparently does not exist in nature.

1955 Bull. Atomic Scientists Oct. 287/3 The long-lived useful products radiocaesium and radiostrontium will be separated from the rest of the fission products and concentrated into radioactive sources.

1993 Guardian 18 Nov. ii. 12/4 Hello and goodbye to the tiny village of Lelev, soon to be dismantled, when anybody can work out how to do it without sending up showers of radiocaesium.