Wikipedia:Reference desk/Archives/Science/2017 March 15

= March 15 =

Fire engines on rails?
Are there currently, or were there ever, fire engines which ran on rails (either rail-only, or road-to-rail)? Also, while I'm sure there aren't any such engines now, but were there ever steam locomotives which were outfitted to fight fires using their onboard water supply (similar to Belle in Thomas & Friends)? If there were (or still are) any such fire engines, what is/was their firefighting niche? 2601:646:8E01:7E0B:45D4:4D76:B31B:9250 (talk) 10:37, 15 March 2017 (UTC)
 * I know of no such engines, as dedicated fire-fighting vehicles - either locomotives or trucks.
 * However railway wagons are a convenient way to move things, and it's easy to put a fire engine or a pump and tank combination, onto a flat wagon and then move that around the railway. These were widely used during the bombing of WWII, for the dockyards that already had good rail access and were bombing targets. The UK produced a few standard designs of trailer-pulled fire pump and as well as being towed on the road, these were used from rail wagons.   More recently, preserved steam railways in the '70s and '80s (after the withdrawal of steam in the UK) often had a problem with lineside fires in inaccessible places and so these also made use of them, as the site could be more easily accessible by rail than by road. Andy Dingley (talk) 10:56, 15 March 2017 (UTC)
 * A quick google came up with the Burlington Northern Santa Fe (BNSF) Fire Train. http://www.firefighternation.com/articles/2013/11/bnsf-railway-s-unique-firefighting-tank-car.html amongst other webpages and there is a video on youtube. --TrogWoolley (talk) 12:09, 15 March 2017 (UTC)

The answer is yes. I've placed an illustration of one at right. A Google search for "firefighting trains" will find articles about this or a similar one, and plenty of others today: 

Their niche is, as you might expect, fighting fires that are close to the railway tracks and not close to roads.

The above examples are modern, but at least one railway, the Southern Pacific, also had firefighting trains in steam days. They did not use the steam locomotive's water supply (which the train needed in order to move), but carried separate water tanks.

--76.71.6.254 (talk) 12:11, 15 March 2017 (UTC)


 * The Swiss firefighting trains are presumably useful because of the large number of (rail-only) tunnels there. If there's an accident inside a tunnel and a train catches fire, there's no way to reach it except with another train. --79.237.64.244 (talk) 04:41, 16 March 2017 (UTC)

Wait... what? You mean Thomas the Tank Engine & Friends isn't a documentary about actual trains who live on the Island of Sodor??? (Sniffle). --Guy Macon (talk) 04:55, 17 March 2017 (UTC)


 * In Belgium, they have two MAN "road-rail fire-fighting vehicles" for the underground sections of the Diabolo project. See Road-rail fire engines protect Diabolo link.  Alansplodge (talk) 20:50, 17 March 2017 (UTC)


 * Thanks, all! I see now that firefighting trains do really exist, and do have an important use! 2601:646:8E01:7E0B:1812:83B6:C84E:722 (talk) 02:42, 18 March 2017 (UTC)

Microwave oven effectiveness decline with use
I know that a microwave oven becomes less effective with use but I don't know whether this means it consumes less electrical power or because it becomes less efficient and consumes the same power. Which is it? — Preceding unsigned comment added by 192.41.131.255 (talk) 11:02, 15 March 2017 (UTC)
 * The microwave emission from the Cavity magnetron, a kind of Vacuum tube decreases as the cathode coating degrades. As a result, If a new microwave oven boils a cup of water in one minute, after five or 10 years it may take 90 seconds. The oven remains usable but consumes more energy to do the same job slower. See Microwave oven. Blooteuth (talk) 14:25, 15 March 2017 (UTC)

Does insufficient protein intake seemes as causing Erectile dysfunction in a healthy person?
Does insufficient protein intake seemes as causing Erectile dysfunction in a healthy person?

If it is, than what is the mechanism? I didn't find information on this in Erectile dysfunction. 77.179.179.98 (talk) 15:57, 15 March 2017 (UTC)


 * Erectile dysfunction is usually a matter of blood flow, or hormone levels. Neither of these is directly related to protein insufficiency per se, although if you get to the point of muscle wasting there might be other complicating factors, such as the fact that lean muscle mass tends to increase testosterone levels.  So, basically, "no, but..." and if you have a specific concern, see a medical professional. μηδείς (talk) 18:42, 15 March 2017 (UTC)


 * "Low levels of protein are linked to high levels of sex-binding globulin, which locks up testosterone so the body can't use it, according to a study by Dr. Christopher Langcope of the University of Massachusetts Medical School.": . Now low testosterone reduces libido, but that's not quite the same as erectile dysfunction, which is when a male with the desire is still unable to get an erection.  The two conditions might be confused, however, especially if the male in question hides the fact that he has no interest in sex with his partner. StuRat (talk) 20:31, 15 March 2017 (UTC)


 * Hiding the fact that he has no interest in sex with his partner is matrimonial deceit not erectile dysfunction. The point about erectile dysfuncition is that erection is desired but unobtainable. Richard Avery (talk) 09:28, 16 March 2017 (UTC)


 * Agreed. StuRat (talk) 04:49, 17 March 2017 (UTC)


 * Dunno, have always had the opinion that libido as purely male is fallatio. ? μηδείς (talk) 02:24, 18 March 2017 (UTC)
 * Larry Miller used to say that the difference in libido between men and women is like the difference between shooting a bullet and throwing it. ←Baseball Bugs What's up, Doc? carrots→ 02:50, 18 March 2017 (UTC)

Solubility of sugar in salt solutions
What data are available on the solubility of sucrose in sodium chloride and other salts aqueous solutions compared to solutions without salts? Is there any salt that could increase the solubility of sugar compared to solubility in pure water?--5.15.12.130 (talk) 19:15, 15 March 2017 (UTC)


 * I have not found any research paper on the subject of solubility of sucrose in saline solution, per se. But I have found this article, which suggests that NaCl and C12H22O11 both dissolve in water fully. For solubilities of NaCl and C12H22O11, you may check out this picture. Apparently, they dissolve independently of each other. One does not act as a catalyst or inhibitor for the other. 50.4.236.254 (talk) 00:52, 16 March 2017 (UTC)

Reference:


 * See also Salting out. But some otherwise insoluble carbohydrates, like chitin can be dissolved in N,N-dimethylacetamide and lithium chloride. Graeme Bartlett (talk) 01:06, 16 March 2017 (UTC)
 * I've tried to test the solubility of sugar in a saturated salt solution. The noticed result has been indeed salting out with the solubility reduced to about half compared to pure water.--5.15.12.130 (talk) 17:40, 16 March 2017 (UTC)
 * Dissolving kinetics are an independent situation (some standard test protocols take at least an hour or several). No idea what your exact protocol was to be able to comment further. DMacks (talk) 03:39, 17 March 2017 (UTC)
 * Apparently there is cooperative effect of sucrose and sodium chloride dissolving in water, where presence of either one increases solubility of the other. See:
 * DMacks (talk) 01:47, 16 March 2017 (UTC)
 * It seems that salting in for sugar at some concentrations range is given only by urea.--5.15.12.130 (talk) 17:57, 16 March 2017 (UTC)
 * I notice that the mentioned journal The International Sugar Journal is not present on Wikipedia!--5.15.12.130 (talk) 18:05, 16 March 2017 (UTC)
 * I notice that the mentioned journal The International Sugar Journal is not present on Wikipedia!--5.15.12.130 (talk) 18:05, 16 March 2017 (UTC)

Can sugar(s) present both salting out and in by the same salt?(another related question in this context) Thanks!--5.15.12.130 (talk) 18:15, 16 March 2017 (UTC)

What quantitative data regarding the intensity of salting in and out are there as a function of mixing ratio(s) of sugar-water-salt? (I see that these articles salting in and salting out are rather lacking quantitative data! Also I see that there is only fucose (data page).)--5.15.12.130 (talk) 18:38, 16 March 2017 (UTC)


 * More refs:
 * —discusses and cites refs for in-solution interactions between salt and sugar, and that it can be concentration-dependent: at low concentration, repulsive forces dominate and cause salting out; at high concentration, salt–sugar complexes for and cause salting in.
 * —has graphs and data for the effect of concentration of various salts on solubility of sucrose and the effect of concentration of sucrose on the solubility of various salts, and data tables for KCl in particular.
 * DMacks (talk) 03:39, 17 March 2017 (UTC)

How do double sided cylinder locks work?
(I sort of asked a related question to this several years ago - but I remain puzzled.)

Our front door has a cylinder lock into which the key can be inserted from either side, in both cases with the spine uppermost (so it isn't pivoting levers) and the key is NOT symmetrical along its length. Additionally if a key is inserted on the inside and partly turned, an outside key can also be fully inserted and it freely rotates, achieving nothing. On realizing that you can't lock the door because the key is on the inside, you remove that key and the outside key still does nothing. So you remove the outside key and reinsert it and the door can be locked.

Without doubt, the mechanism is more involved than. So, how does it work please? -- SGBailey (talk) 19:56, 15 March 2017 (UTC)


 * Not having examined your front door, I can only speculate from experience. Most likely the set up is similar to this, with two separate but identically keyed lock cylinders and a mechanism to disengage one of there is other is turned. If you live in Europe the setup is most likely like this , which is the same thing in a different package. WegianWarrior (talk) 20:19, 15 March 2017 (UTC)


 * Your second image looks plausible - they obviously have to have good tolerancing on the split positions in the pegs, but that isn't hard these days. Thanks. -- SGBailey (talk) 23:57, 15 March 2017 (UTC)


 * There are two lock cylinders, quite independent. The bolt is worked from the centre, between the two of them, and is operated by a loose dog clutch. Turning either cylinder can activate the bolt. If it's a removable one-piece Euro cylinder (or its variants), this dog clutch is between the cylinders and rotates a single "tooth" around it, which drives the bolt.
 * A drawback to some of these, if poorly engineered, is that the bolt can be moved back or forth without needing to defeat the key cylinder, by using some sort of wire pick around the cylinder and working the bolt directly. Andy Dingley (talk) 00:25, 16 March 2017 (UTC)
 * Sounds like a not-very-dead dead bolt. DMacks (talk) 01:30, 16 March 2017 (UTC)
 * It can be either - a dead bolt, or a sprung sash bolt. Andy Dingley (talk) 11:37, 16 March 2017 (UTC)
 * → -- Hans Haase (有问题吗) 19:54, 16 March 2017 (UTC)