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  2. Half-life - Wikipedia

    en.wikipedia.org/wiki/Half-life

    In this situation it is generally uncommon to talk about half-life in the first place, but sometimes people will describe the decay in terms of its "first half-life", "second half-life", etc., where the first half-life is defined as the time required for decay from the initial value to 50%, the second half-life is from 50% to 25%, and so on.

  3. Biological half-life - Wikipedia

    en.wikipedia.org/wiki/Biological_half-life

    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 ...

  4. Human serum albumin - Wikipedia

    en.wikipedia.org/wiki/Human_serum_albumin

    It has a serum half-life of approximately 21 days. [6] It has a molecular mass of 66.5 kDa. The gene for albumin is located on chromosome 4 in locus 4q13.3 and mutations in this gene can result in anomalous proteins. The human albumin gene is 16,961 nucleotides long from the putative 'cap' site to the first poly(A) addition site. It is split ...

  5. N-end rule - Wikipedia

    en.wikipedia.org/wiki/N-end_rule

    The N-end rule is a rule that governs the rate of protein degradation through recognition of the N-terminal residue of proteins. The rule states that the N-terminal amino acid of a protein determines its half-life (time after which half of the total amount of a given polypeptide is degraded).

  6. Radioactive tracer - Wikipedia

    en.wikipedia.org/wiki/Radioactive_tracer

    11 C decays by positron emission with a half-life of ca. 20 min. 11 C is one of the isotopes often used in positron emission tomography. [3] 14 C decays by beta decay, with a half-life of 5730 years. It is continuously produced in the upper atmosphere of the earth, so it occurs at a trace level in the environment.

  7. List of radioactive nuclides by half-life - Wikipedia

    en.wikipedia.org/wiki/List_of_radioactive...

    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.

  8. Isotopes of nitrogen - Wikipedia

    en.wikipedia.org/wiki/Isotopes_of_nitrogen

    It has a short half-life of about 7.1 s, [4] but its decay back to 16 O produces high-energy gamma radiation (5 to 7 MeV). [ 4 ] [ 10 ] Because of this, access to the primary coolant piping in a pressurised water reactor must be restricted during reactor power operation. [ 10 ]

  9. Stable nuclide - Wikipedia

    en.wikipedia.org/wiki/Stable_nuclide

    However, the half-life of this nuclear isomer is so long that it has never been observed to decay, and it thus is an "observationally stable" primordial nuclide, a rare isotope of tantalum. This is the only nuclear isomer with a half-life so long that it has never been observed to decay. It is thus included in this list.