Wikipedia:Reference desk/Archives/Science/2018 September 3

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September 3

Fission of U-236

My inorganic chemistry textbook has a section on the origin of the elements where it goes over some nuclear physics in brief. My question relates to this excerpt. Actually I have two questions. Firstly, is the equation given for the spontaneous fission of U-236 correct? The mass doesn't seem to balance. I think the correct equation should be:

²³⁶
₉₂U
→ ¹⁴⁰
₅₄Xe
+ ⁹³
₃₈Sr
+ 3
n

Secondly, in their determination of the energy released, shouldn't we take into account the binding energy of the free neutron(s)? I'm not exactly sure how to take into account that binding energy, but I would imagine that a significant amount of energy would be needed to unbind neutrons from the nucleus. 202.155.85.18 (talk) 07:52, 3 September 2018 (UTC)

An arrow does not imply a balanced equation, only = sign does. As to the binding energy it is zero for free nucleons including neutrons, so it is correctly ignored. Ruslik_Zero 13:02, 3 September 2018 (UTC)

An arrow does not imply a balanced equation. Really? Per Nuclear reaction:

Nuclear reactions may be shown in a form similar to chemical equations, for which invariant mass must balance for each side of the equation, and in which transformations of particles must follow certain conservation laws, such as conservation of charge and baryon number (total atomic mass number).

So I think you are right that there really should have been a "3" there. But as Ruslik says, free nucleons have zero binding energy by definition of that concept, so it didn't matter here. --ToE 16:55, 3 September 2018 (UTC)

I suppose that, in fairness, an unbalanced equation is not wrong. It's just not balanced. And since we didn't need to balance it to get the correct answer, for this purpose, balancing was not required. That said, an equality sign would be wrong, because it would imply reversibility. 202.155.85.18 (talk) 01:23, 4 September 2018 (UTC)

This problem seems a bit contrived since, as far as I can tell, U-236 never undergoes spontaneous fission, but if left to its own devices, will only undergo an alpha decay (t_1⁄2=23.42x10⁶y).

According to the French Wikipedia, U-236 does undergo spontaneous fission. 202.155.85.18 (talk) 01:11, 4 September 2018 (UTC)

In The Nuclear Fission Process, data on the spontaneous fission of U-236 (among other radioactive isotopes) is given on page 37. 202.155.85.18 (talk) 01:18, 4 September 2018 (UTC)

Our isotopes of uranium gives spontaneous fission of U-236 as a known decay mode of 9.6×10⁻⁸% occurance. DMacks (talk) 02:10, 4 September 2018 (UTC)

Thank you both. I see that NFP gives it a T_1/2 (SF) of (2.48 ± 0.11) x 10¹⁶ years. -- ToE 00:50, 13 September 2018 (UTC)

Non-CYP2D6 pain killers

Please may you name some pain killers that hospitals routinely prescribe to patients that do not rely on the CYP2D6 pathway. For example when the patient is a poor CYP2D6 metabolizer whos body cannot convert codeine to morphine. Thanks for your time and help. — Preceding unsigned comment added by 77.101.141.178 (talk) 14:56, 3 September 2018 (UTC)

There is at least one, but (per disclaimer on top of page) ... "ask your doctor or a medical professional". 2606:A000:1126:4CA:0:98F2:CFF6:1782 (talk) 20:22, 3 September 2018 (UTC)

You answered your own question; morphine. Abductive (reasoning) 03:09, 4 September 2018 (UTC)

Characteristics of common wasps and bees (II)

Regarding my corresponding inquiry, I would like to once more ask for some more comments on the matter. Especially, I am still certain that common wasps and yellow jackets are indeed attracted by artificial light (e. g. cf. this information by the Oxford City Council) – very much as the table states for hornets.--Neufund (talk) 20:12, 3 September 2018 (UTC)

The article's talk page is probably the best place to discuss this; or edit the table yourself (?). Here is a source for paper wasps being attracted to light:[1]. 2606:A000:1126:4CA:0:98F2:CFF6:1782 (talk) 21:10, 3 September 2018 (UTC)

I took the liberty of editing the table (inelegantly, perhaps) for paper wasps/light. 2606:A000:1126:4CA:0:98F2:CFF6:1782 (talk) 21:46, 3 September 2018 (UTC)

What do these words mean in dentistry?

Any dentists around? Could someone please define the terms provisionalize (noun: provisionalization) and temporize (temporization)? I think they might be synonyms and I suppose they have something to do with temporary/short-term dental work. Equinox ◑ 21:41, 3 September 2018 (UTC)

According to a dental surgeon, which is inline with Google results, they are similar but not the same. Provisionalize has to do with an implant. The provisionalization is a quick, usually same-day, implant placed where the final implant will go. It lets you do a root canal, place a stud, and put in a provisional tooth all at once. Then, when the final tooth arrives, it is easy to remove the provisional tooth and replace it without surgery. Previously, there would be a root canal surgery, a wait, then another surgery to place the stud and implant. Apparently it is important that the provisionalization doesn't touch other teeth (or "occlude" other teeth). As for temporization, that is a temporary dental item, such as a cap or veneer. It is not temporary to be replaced with a final item. It is just temporary to eventually be discarded, possibly replaced with another temporary item. 216.59.42.36 (talk) 14:09, 4 September 2018 (UTC)