Science desk
< May 25	<< Apr \| May \| Jun >>	May 27 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

May 26

burning eye by acidic stuff vs basic stuff

I read in the past that burning of the eyes from basic stuff is more dangerous from the burning the eyes by acidic stuff. Is that true? What is the explanation for that? — Preceding unsigned comment added by 5.28.171.142 (talk) 01:44, 26 May 2015 (UTC)[reply]

Bases are more damaging to many body tissues because of their ability to saponify things like fatty acids. --Jayron 32 02:00, 26 May 2015 (UTC)[reply]

Thanks, but Actually I didn't understand the answer. 5.28.171.142 (talk) 11:44, 26 May 2015 (UTC)[reply]

The base converts the fat into soap. This is saponification. It can also break up proteins. So strong bases (alkali) can dissolve animal flesh like eyeballs. Graeme Bartlett (talk) 13:15, 26 May 2015 (UTC)[reply]

How dangerous an acid/base is related to how concentrated the solution is or what the pH is, so a general statement about one being "more dangerous" can be iffy. (For example, a weak solution of sodium bicarbonate is generally less dangerous than a concentrated solution of nitric acid.) Concentrated acidic solutions can also break up proteins and fats (see acid hydrolysis). If you want to compare which are more destructive, you'd have to start getting into details. - That said, one issue is that pain detecting nerves are sensitive to acid, but less sensitive to basic/alkaline conditions [1]. This means that if you get acid onto your skin or into your eye, you tend to feel it immediately and run to wash it off or start tearing up to flush it out of the eye. In contrast, you might not recognize the severity of getting a highly basic solution on you until there is significant damage. I've heard stories of people who unknowingly got highly basic solutions on them and were unaware of it until they visually noticed a quite serious wound. -- 160.129.138.186 (talk) 15:53, 26 May 2015 (UTC)[reply]

Why and how alcohol kills bacteria?

5.28.171.142 (talk) 11:43, 26 May 2015 (UTC)[reply]

The alcohol can suck the water out of the bacteria. This is due to osmotic pressure. Graeme Bartlett (talk) 13:19, 26 May 2015 (UTC)[reply]

Tonicity is also a good relevant reading. --Jayron 32 15:03, 26 May 2015 (UTC)[reply]

Oligocene Drowning

Where can I find out more about the (possibly alleged) period known as the "Oligocene Drowning", about 30 million years ago when New Zealand was (allegedly) mostly/entirely under-water?

There doesn't seem to be anything about it on Wikipedia.

I've searched and found a little info, but I'm not sure which of the sources are credible - and whether the 'popular' view is that it is probably true or probably false.

I don't mind if the info isn't online, if there's some book/s or something I can get.

88.104.30.112 (talk) 11:56, 26 May 2015 (UTC)[reply]

I don't know about the name, but there is evidence that there were few if any land areas left by the early Miocene [2] [3] [4]. Mikenorton (talk) 12:13, 26 May 2015 (UTC)[reply]

Great, thanks, I'll definitely read those for some background.

The name seems to be specific to NZ; I was looking at info about extinctions and evolution of megafauna there, when I came across it. 88.104.30.112 (talk) 12:40, 26 May 2015 (UTC)[reply]

I recommend Google Scholar (http://scholar.google.com) for questions like this. A search for "New Zealand Oligocene drowning" finds quite a number of sources, several available online. A very recent source that gives background on the question is http://www.researchgate.net/profile/Neil_Gemmell/publication/272622697_Analyses_of_the_mitochondrial_genome_of_Leiopelma_hochstetteri_argues_against_the_full_drowning_of_New_Zealand/links/54ea6c660cf2f7aa4d577306.pdf. Looie496 (talk) 12:53, 26 May 2015 (UTC)[reply]

You can read Zealandia_(continent). Ruslik_Zero 20:40, 26 May 2015 (UTC)[reply]

Oligocene#Oceans is relevant, given the fall and rise of ocean levels worldwide since then. μηδείς (talk) 03:04, 27 May 2015 (UTC)[reply]

Cattle bathing in the Andaman Sea

I saw a documentary on the Rudy Maxa's World episode "Thailand, Andaman Islands" that showed the local cattle (gnus ?) wading out in the sea at sunset. This seems like odd behavior to me. He didn't explain it. I can't imagine they are trying to cool down, as that would make more sense at mid-day or earlier afternoon. Does this get rid of parasites ? Why else would they do it ? StuRat (talk) 19:27, 26 May 2015 (UTC)[reply]

I'd imagine it'd be a water buffalo, as our article on gnus states that they are endemic to Africa, and not southeast Asia. --OuroborosCobra (talk) 20:45, 26 May 2015 (UTC)[reply]

Yes, that makes sense. Water_buffalo#Ecology_and_behavior says they use the water for "thermoregulation". I doubt if they use it to keep warm, so that would mean they use it to cool down. I'm still curious why they would need to cool down at sunset, though, as opposed to the hottest part of the day. StuRat (talk) 21:16, 26 May 2015 (UTC)[reply]

Midsummer high temperatures peak at about 6:00 PM, which while not actually sunset on the dot, is closer to sunset than to noon. That would mean the time period from 6:00 PM until sunset would be the warmest chunk of time during the day. --Jayron 32 04:41, 27 May 2015 (UTC)[reply]

Note though that that plot is for latitude 45 degrees, corresponding roughly to Minneapolis, where sunset occurs around 9 PM in midsummer. For the Andaman Islands, at latitude 10 degrees, sunset is right around 6 PM even at midsummer, and the high temperature occurs hours earlier. I lived in Tucson for many years, and my experience was that the midsummer high temperatures usually occurred at 3-4 PM. Looie496 (talk) 13:50, 27 May 2015 (UTC)[reply]