The isolation of 55 S particles from mitochondria has been reported. Evidence has been presented which emphasizes the importance of adequate control of contamination during preparation of mitochondria. A satisfactory mitochondrial purification method was attained through the use of radioactive microsomal fractions and electron microscopy to assess the contamination of mitochondria and ribosomes...

Numerous sites worldwide have been identified as having significant radioactive contamination, either as a result of routine or accidental releases. The radiological impact of this contamination depends on the extent to which the radionuclides are taken up by organisms, including humans. The mobility, and thus availability, of the radionuclides is greatly determined by the physico-chemical form...

NASA’s Chandra X-ray Observatory includes a Flight Contamination Monitor (FCM), a system of 16 radioactive calibration sources mounted to the inside of the Observatory’s forward contamination cover. The purpose of the FCM is to verify the ground-to-orbit transfer of the Chandra flux scale, through comparison of data acquired during the ground calibration with those obtained in orbit, immediatel...