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This is a list of radioactive nuclides (sometimes also called isotopes), ordered by half-life from shortest to longest, in seconds, minutes, hours, days and years. Current methods make it difficult to measure half-lives between approximately 10 −19 and 10 −10 seconds.
A biological half-life or elimination half-life is the time it takes for a substance (drug, radioactive nuclide, or other) to lose one-half of its pharmacologic, physiologic, or radiological activity. In a medical context, the half-life may also describe the time that it takes for the concentration of a substance in blood plasma to reach one ...
Not all molecules in the solution have a P-32 on the last (i.e., gamma) phosphate: the "specific activity" gives the radioactivity concentration and depends on the radionuclei's half-life. If every molecule were labelled, the maximum theoretical specific activity is obtained that for P-32 is 9131 Ci/mmol.
Aluminium can capture a neutron and generate radioactive sodium-24, which has a half life of 15 hours [9] [10] and a beta decay energy of 5.514 MeV. [11] The activation of a number of test target elements such as sulfur, copper, tantalum, and gold have been used to determine the yield of both pure fission [12] [13] and thermonuclear weapons. [14]
As an extreme example, the half-life of the isotope bismuth-209 is 2.01 × 10 19 years. The isotopes in beta-decay stable isobars that are also stable with regards to double beta decay with mass number A = 5, A = 8, 143 ≤ A ≤ 155, 160 ≤ A ≤ 162, and A ≥ 165 are theorized to undergo alpha decay.
The activity of the daughter is given by the Bateman equation: = () + (), where and are the activity of the parent and daughter, respectively. and are the half-lives (inverses of reaction rates in the above equation modulo ln(2)) of the parent and daughter, respectively, and BR is the branching ratio.
As time passes after such material has formed, uranium-234 in the sample with a half-life of 245,000 years decays to thorium-230. [4] Thorium-230 is itself radioactive with a half-life of 75,000 years, [ 4 ] so instead of accumulating indefinitely (as for instance is the case for the uranium–lead system), thorium-230 instead approaches ...
In clinical practice, this means that it takes 4 to 5 times the half-life for a drug's serum concentration to reach steady state after regular dosing is started, stopped, or the dose changed. So, for example, digoxin has a half-life (or t 1 / 2 ) of 24–36 h; this means that a change in the dose will take the best part of a week to ...