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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. Island of stability - Wikipedia

   en.wikipedia.org/wiki/Island_of_stability

   Considering all decay modes, various models indicate a shift of the center of the island (i.e., the longest-living nuclide) from 298 Fl to a lower atomic number, and competition between alpha decay and spontaneous fission in these nuclides; [83] these include 100-year half-lives for 291 Cn and 293 Cn, [55] [78] a 1000-year half-life for 296 Cn ...

4. Decay chain - Wikipedia

   en.wikipedia.org/wiki/Decay_chain

   This nuclide was long thought to be stable, but in 2003 it was found to be unstable, with a very long half-life of 20.1 billion billion years; [5] it is the last step in the chain before stable thallium-205. Because this bottleneck is so long-lived, very small quantities of the final decay product have been produced, and for most practical ...

5. 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.

6. Exponential decay - Wikipedia

   en.wikipedia.org/wiki/Exponential_decay

   A more intuitive characteristic of exponential decay for many people is the time required for the decaying quantity to fall to one half of its initial value. (If N(t) is discrete, then this is the median life-time rather than the mean life-time.) This time is called the half-life, and often denoted by the symbol t 1/2. The half-life can be ...

7. List of unsolved problems in chemistry - Wikipedia

   en.wikipedia.org/wiki/List_of_unsolved_problems...

   Protein folding problem: Is it possible to predict the secondary, tertiary and quaternary structure of a polypeptide sequence based solely on the sequence and environmental information? Inverse protein-folding problem: Is it possible to design a polypeptide sequence which will adopt a given structure under certain environmental conditions?

8. 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 ...

9. Branching fraction - Wikipedia

   en.wikipedia.org/wiki/Branching_fraction

   Here the problem with the term partial half-life is evident: after (341+6.60) days almost all the nuclei will have decayed, not only half as one may initially think. Isotopes with significant branching of decay modes include copper-64 , arsenic-74 , rhodium-102 , indium-112 , iodine-126 and holmium-164 .