Wikipedia:Reference desk/Archives/Science/2024 March 26

= March 26 =

If Neptune was named Janus, what will be the name of element 93?
The first suggestion of Neptune is Janus (by Galle), if Neptune was named Janus instead of Neptune, what will be the name (and the symbol) of the element neptunium (element 93), which was named after Neptune? 125.230.237.23 (talk) 04:05, 26 March 2024 (UTC)


 * We don't answer requests for opinions, predictions or debate. 41.23.55.195 (talk) 05:07, 26 March 2024 (UTC)


 * It's safe to say the element would have a different name. ←Baseball Bugs What's up, Doc? carrots→ 08:24, 26 March 2024 (UTC)
 * The elements named after astronomical objects named after mythological figures whose name in Latin ends in the second-declension suffix -us (Neptunus, Uranus) replace the suffix by -ium. This is also the most common suffix for other element names. An author writing a novel set in an alternate universe in which a planet came to be named Janus could believably use the name janium for a later discovered or synthesized element. In the novel's universe so many things may diverge from our universe (in fact, should, to make it a compelling read) that there is little reason for this thus-named element to be specifically that with the atomic number 93. --Lambiam 11:27, 26 March 2024 (UTC)

Copper IUD end of life
The Copper IUD article mentions that they have a limited life time, but does not mention why the life time is limited.

I am imagining two possible ways in which this happens:

1. the copper slowly erodes. eventually the amount of copper left is too small to be effective

2. the amount of copper left is always sufficient, but a coating slowly develops over time. Eventually the amount of coating is so great that there is insufficient copper released.

Which is more correct in this case? Or is it a combination of both? Or is it some other mechanism? OptoFidelty (talk) 05:25, 26 March 2024 (UTC)


 * "Unlike an ordinary IUD which is left in the uterus indefinitely, the copper IUD may need to be replaced when the copper is exhausted, usually after about two years, in order to retain contraceptive efficacy."    However, "The higher pregnancy rate among the women who continued to use their copper 7 device for a third year suggests that although the copper is still there, it is not available for contraceptive action. ... Examination under the microscope showed hard deposits of material on the surface of these copper 7 IUDs, which Gosden et a1 have shown is a layer of calcium, which would seriously interfere with the contraceptive action of the available copper. This may explain the highly significant difference in the pregnancy rates seen in our two groups-12 pregnancies in the continuation group during the third year of use and no pregnancies in the replacement group. Even allowing for possible differences in the fertility rates of these two groups, which were similar in mean age and parity, this striking difference is remarkable and seems to confirm that although the copper may not be exhausted by three years of use, it may not be available for contraceptive action."  --Lambiam 10:44, 26 March 2024 (UTC)