Wikipedia:Reference desk/Archives/Science/2008 June 24

= June 24 =

Can any microorganisms live in 8N NaOH?
I wouldn't think so, but repeatly I have been surprised to find a stock solution of NaOH with "scuz" in it. I suppose it must be precipitation of NaOH, but it sure doesn't look like it. The solution gets hazy and somewhat snotty stuff sitting on the bottom gets suspended if the bottle is swirled. Is there any reason to believe that this is anything other than precipitation? In case it matters, the solution is in a glass bottle with a plastic cap; inside of the cap has some sort of coated cardboard, I think. ike9898 (talk) 00:31, 24 June 2008 (UTC)
 * There are Alkaliphiles but I think they can't survive on NaOH alone as they need other elements such as carbon and nitrogen to construct their proteins and nucleic acids.-- Lenticel ( talk ) 01:30, 24 June 2008 (UTC)
 * Concentrated NaOH reacts with glass and should not be stored in glass bottles for long. I'm not sure exactly what the precipitate is but I believe it is derived from the glass itself. Adrian J. Hunter(talk•contribs) 01:58, 24 June 2008 (UTC)
 * According to Wikipedia's article on sodium hydroxide, the precipitate is sodium silicate. Adrian J. Hunter(talk•contribs) 02:11, 24 June 2008 (UTC)
 * ...which doesn't quite make sense, since sodium silicate in water-soluble. Hmmm... now I'm confused... Adrian J. Hunter(talk•contribs) 02:23, 24 June 2008 (UTC)
 * Glass has other stuff besides silica, perhaps calcium hydroxide could be formed. Also you may get carbon dioxide from the air making an impact. Graeme Bartlett (talk) 06:00, 24 June 2008 (UTC)
 * It may be soluble in water, but that doesn't mean it's soluble in concentrated NaOH. See Common-ion effect. shoy 14:38, 24 June 2008 (UTC)

So what is a better a container to store such a solution in for up to year? Any plastic bottle? A particular type of plastic? ike9898 (talk) 13:30, 24 June 2008 (UTC)
 * High density polyethylene (the hazy white ones) work pretty well. Most polymeric plastics will work just fine, though when it doubt check with the manufacturer. Materials safety data sheets are usually pretty helpful for that kind of thing as well. 63.172.27.2 (talk) 15:24, 24 June 2008 (UTC)
 * Some plastics used for bottles are unsuitable, such as polycarbonate or Polyethylene terephthalate as they will be dissolved in alkali too. Graeme Bartlett (talk) 21:51, 24 June 2008 (UTC)

Albatrosses and seagulls
Is the albatross a large breed of seagull?? —Preceding unsigned comment added by 84.68.206.60 (talk) 01:24, 24 June 2008 (UTC)
 * Compare Albatross and Gull, particularly the scientific classification in the infoboxes. Confusing Manifestation (Say hi!) 01:28, 24 June 2008 (UTC)

Ice on Mars
How do we know that the white stuff that's sublimated isn't dry ice? Thanks. Imagine Reason (talk) 03:12, 24 June 2008 (UTC)


 * We know the temperature of the soil - which is too hot for dry ice to accumulate. The average temp is -70F.  Dry ice requires below -109F. --  k a i n a w &trade; 03:20, 24 June 2008 (UTC)
 * Thanks, that's been something I've been wondering myself. Has there been water flowing recently? Mac Davis (talk) 04:08, 24 June 2008 (UTC)
 * There is high suspicion of recent water flows. A popular example is a [air of photos that shows some sort of deposit (could be water - could be slush - could be an alien trash dump).  It did a quick Google and found the pair on this page. --  k a i n a w &trade; 04:24, 24 June 2008 (UTC)
 * -109F at 1 atmosphere pressure. According to Atmosphere of Mars, dry ice can sublime (CO2 makes up most of Mars' atmosphere) because atmospheric pressure on Mars is much lower than on Earth. shoy 14:42, 24 June 2008 (UTC)
 * They're saying it'd have done so much faster (Phoenix_(spacecraft)). I just don't understand why no news article I've read mentions the fact. Imagine Reason (talk) 13:47, 25 June 2008 (UTC)

I'm not sure why this is big news. We had photos showing ice caps on mars already. How is this new information? ScienceApe (talk) 20:16, 25 June 2008 (UTC)
 * Because we haven't known for sure what the caps were made of -- dry ice, water ice, or something else entirely. --Carnildo (talk) 21:37, 25 June 2008 (UTC)
 * And pluto is mostly made up of ice. As are comets. And we know that many moons surrounding Jupiter and Saturn have ice on them. Water is the second most common molecule in the universe. Just seemed like people are announcing old news that was already well established in the scientific community. ScienceApe (talk) 03:33, 26 June 2008 (UTC)

Science
 Please help me find something on " The Depletion of the ozone layer and its effect on the earth's vegetation". —Preceding unsigned comment added by 84.54.21.148 (talk) 22:02, 23 June 2008 (UTC)


 * Our article on ozone (not the Moldavian pop group) and ozone depletion may be a good start. But hurry, before it has turned into a hole.  --Cookatoo.ergo.ZooM (talk) 22:13, 23 June 2008 (UTC)
 * (ec) See Ozone depletion and Ozone depletion which has about 3 lines of information. But I'm sure you'll get a (MUCH) better answer at the Science section of the Refdesk which can be found at Reference desk/Science. Zain Ebrahim (talk) 22:17, 23 June 2008 (UTC)


 * Well. according to user:Zain Ebrahim it has already become a hole. WP does - in real time - reflect ozone depletion in - gasp, gasp - oh, bugger it, I thought it was oxygen - croak ...  Help, sinebot,  —Preceding unsigned comment added by Cookatoo.ergo.ZooM (talk • contribs) 22:40, 23 June 2008 (UTC)


 * Countless publications are available, for example: Ozone depletion: threat to photosynthesis.--Stone (talk) 09:51, 24 June 2008 (UTC)

how much kerosene does a lantern takes to burn for 1 hour ?
can i get an estimate or result of any test being conducted over a lantern ? Gunjar (talk) 08:48, 24 June 2008 (UTC)


 * I guess you're trying to estimate how much kerosene to take along on a trip/ caving? There are a lot of factors that influence how much fuel your lamp will go through in a given time period. To name just a few: How tall a flame you produce, the kind of wick you use, how thick it is, humidity, how much oxygen is available to burn (although by the time your lantern dims, you'd be in real trouble) etc.  So theory is not going to be that much help.  Unless someone can come up with a better idea, I'd burn a light in the very lantern you want to take for a little while, drain the kerosene and refill with a measured amount, then run the light for a certain period (e.g. half an hour) and measure how much kerosene was used up.  Then add a certain amount for safety.  This way you'd use up some extra kerosene, but that beats running out of light in a dark spot when you really need to see where you are going.  (before someone squawks, no intention of giving any advice.)80.171.255.133 (talk) 10:02, 24 June 2008 (UTC)


 * In round numbers, the traditional "hurricane lantern" style kerosene lantern will burn "overnight" even when producing a pretty good-sized (maximum non-sooting) flame.


 * Atlant (talk) 11:59, 24 June 2008 (UTC)


 * A traditional kerosene lantern will certainly burn all night without refilling with the maximum non-smoking flame, so the kero burned in 1 hour would not be a huge amount. Why not just do the practical test suggested? I could measure the fuel consumed by one of my lanterns, but it would be different from your lantern. I would weigh it before and after the test burn and just note how many grams lighter it was (the soot deposited and the wick consumed being small compared to the kerosens burned). Edison (talk) 13:32, 24 June 2008 (UTC)


 * an estimate. Very sure it's less than 50 ml per hour.Polypipe Wrangler (talk) 21:55, 28 June 2008 (UTC)

SEM's huge depth of field?
Why do scanning electron microscopes have such a huge depth of field compared to macro photography or microscopes? --antilivedT 09:09, 24 June 2008 (UTC)


 * The electrons are already focused into a very narrow, relatively non-divergent beam in the area of the target (subject) so they illuminate only a very small spot no matter what the "Z-Axis" position (height) of the target is. Also, the distance from the theoretical electron source to the target is very large as compared to the size of the target so the various electron paths (formed as the beam scans around) are nearly parallel; this means there's not much geometric distortion caused by varying heights of different parts of the target.


 * A somewhat-similar optical system is the telecentric lens; In these lenses, one of the optical pupils is located at infinity. In the SEM, the entrance pupil isn't at infinity, but compared to the size of the target, it's "really far away" (that's a technical term, BTW ;-) ).


 * Atlant (talk) 11:54, 24 June 2008 (UTC)

Painting as therapy for mentally ill
In many films we see mentally ill persons painting as a form of therapy. How often is that in real life? Why painting and not other art? GoingOnTracks (talk) 16:13, 24 June 2008 (UTC)
 * Not sure about therapy, but maybe the creativity and mental illness article is worth reading. --88.22.11.48 (talk) 19:03, 24 June 2008 (UTC)
 * See Art therapy but it is very US-centric. In the UK art therapy is widely available and I'm sure it isn't restricted to painting. Itsmejudith (talk) 20:23, 24 June 2008 (UTC)
 * See also expressive therapy. There's all different types: music therapy, dance therapy, etc. Mangostar (talk) 22:57, 24 June 2008 (UTC)

Psychology: When having children... Is it true that men prefer little girls and women prefer little boys??
I have heard this many many times and I don't know if it's true. This section is about psychology and I want to know your opinion. Thanks and greetings. Sorry if I don't speak English very well. Go Bless You. 190.49.105.122 (talk) 17:39, 24 June 2008 (UTC)


 * It's certainly not always true. It might be true on average, I haven't read any studies into it. There are other factors to consider though - for example, if the couple already have a boy, they will probably prefer their second child to be a girl, and vice versa. --Tango (talk) 18:04, 24 June 2008 (UTC)


 * I have never heard that men prefer little girls and women prefer little boys.
 * In some cultures around the world (particularly China and the Middle Eastern countries), you see a definite bias toward having male children.
 * Most couples I know in the United States want one child of each gender. There's also an argument for women wanting girls and men wanting boys in the sense of being able to buy them toys you never got when you were a child! ~Amatulić (talk) 22:27, 24 June 2008 (UTC)
 * I'm sure this varies by country. Some evidence about gender preferences for... the United States, 17 countries in Europe, Nepal Mangostar (talk) 08:25, 25 June 2008 (UTC)


 * I don't think it's true. In fact, I'd guess that the reverse is actually true and the dads who want daughters and the moms who want sons simply stick out as being contrary to "popular" opinion. That is, it seems prevalent because we think of it as odd. In a similar fashion, we have expressions like "mama's boy" and "daddy's little girl", but we don't have the complementary expressions; being a "mama's girl" wouldn't be something of note. Matt Deres (talk) 16:50, 25 June 2008 (UTC) <-a dad who desperately wanted a daughter!

Weight of sails and ropes
What was the weight of sailcloth plus ropes (i.e. everything made of flax or hemp) on a typical 18th/19th century ship, for example a man-of-war or a ship of the line? --Ayacop (talk) 17:54, 24 June 2008 (UTC)


 * I'd say it's in the hundreds of pounds, based on limited experience handling similar materials. You could approximate the value by going to a hardware store and looking at the weight of a painter's canvas tarp and getting the weight per square yard. Or maybe it's similar to the weight of denim. Hemp rope should be easy to find too.
 * Once you have that information, you need to figure out which sail plan you want to calculate; I assume you mean a fully rigged ship. I can't find sail dimensions for these sail plans, though. And I failed to find anything in terms of area density for hemp cloth. Hope someone else can help. ~Amatulić (talk) 22:46, 24 June 2008 (UTC)


 * For a problem like this you can search the web for "sailcloth weighs" which will lead you to the information that 7 square feet weighs 1lb which means the weight of one mainsail can be over a ton.--Shantavira|feed me 08:17, 25 June 2008 (UTC)

bumblebee behavior
When walking to the bus today, I saw three or four (couldn't figure that out) bumblebees wrestling/mating/locked in mortal combat, tangled up and squirming in a ball on the ground. Anyone have any idea what they were doing that could look like this? (I'm in California so it's midsummer if that affects the analysis.) Mangostar (talk) 22:55, 24 June 2008 (UTC)


 * Bumblebee colony populations are quite small (up to 50 bees), and males are routinely ejected. They may bring a queen with them to start a new nest somewhere. A handful of bumblebees can represent a significant chunk of a colony, so perhaps this group of bees was "swarming" (as it were) and mating on its way to establishing a new nest. ~Amatulić (talk) 23:13, 24 June 2008 (UTC)
 * Interesting... Mangostar (talk) 08:15, 25 June 2008 (UTC)
 * I had the pleasure of witnessing a mass mating event two weeks ago. I don't know if they were bees or wasps, but they all flew only a few inches from the ground, all trying to find mates. From what I could gather, the males all had their territory that they stayed in, of about a four foot radius. If a female or another male got in its space, it would attack/intercourse. Sometimes those turned into balls which would explode, then reform, and explode. It was pretty cool. Do you know if they were actually bumblebees? Was it only one ball, or were there a lot of bees out? Mac Davis (talk) 23:28, 24 June 2008 (UTC)
 * They definitely looked like bumblebees to me, very fuzzy. And there weren't any other bees that I could see on the sidewalk. Mangostar (talk) 08:15, 25 June 2008 (UTC)
 * There's also the fascinating bee ball. --Sean 00:23, 25 June 2008 (UTC)
 * How do the bees know when to let go? Mac Davis (talk) 17:13, 25 June 2008 (UTC)