Search results
Results from the WOW.Com Content Network
Carbon-14, C-14, 14 C or radiocarbon, is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons. Its presence in organic matter is the basis of the radiocarbon dating method pioneered by Willard Libby and colleagues (1949) to date archaeological, geological and hydrogeological samples.
When an organism dies, the exchange of 14 C with the environment ends and the incorporated 14 C decays. Given radioactive decay (14 C's half-life is about 5,730 years), the relative amount of 14 C left in the dead organism can be used to calculate how long ago it died. Bomb pulse dating should be considered a special form of carbon dating.
A good example of the difference in energy of the various radionuclei is the detection window ranges used to detect them, which are generally proportional to the energy of the emission, but vary from machine to machine: in a Perkin elmer TriLux Beta scintillation counter , the hydrogen-3 energy range window is between channel 5–360; carbon-14 ...
Two are stable and not radioactive: carbon-12 (12 C), and carbon-13 (13 C); and carbon-14 (14 C), also known as "radiocarbon", which is radioactive. The half-life of 14 C (the time it takes for half of a given amount of 14 C to decay) is about 5,730 years, so its concentration in the atmosphere might be expected to decrease over thousands of ...
C than is found in the animal's diet, though for different biochemical reasons. The enrichment of bone 13 C also implies that excreted material is depleted in 13 C relative to the diet. [15] Since 13 C makes up about 1% of the carbon in a sample, the 13 C / 12 C ratio can be accurately measured by mass spectrometry. [16]
Carbon monoxide rebreathing is used to monitor athletes' haemoglobin levels, which are a predictor of exercise performance but there has been suggestions that repeated inhalation can be used to ...
For biological effects of substances such as radioactive iodine the ingestion of non-radioactive isotopes may substantially reduce the biological uptake of the radioactive form, and chelation therapy may be applied to accelerate the removal of radioactive materials formed from heavy metals from the body by natural processes.
The study, which was published in the journal Chemosphere, detailed how high levels of these flame retardants were found in kitchen utensils, food containers, trays used to hold meat and even toys ...