Science desk
< August 3	<< Jul \| August \| Sep >>	Current desk >

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

August 4

Thermal treatment of meat, chicken and vegetables - what is the end result of microscopic changes?

That's what I would like to know. What happens if you boil such foods for half an hour. AboutFace 22 (talk) 00:31, 4 August 2020 (UTC)[reply]

Protein denaturing for one. Sagittarian Milky Way (talk) 00:45, 4 August 2020 (UTC)[reply]

In the traditional recipe for carbonade flamande (a beef stew), tough, dry, and sinewy cuts of meat such as foreshank are simmered for hours (see Simmering#Dutch and Flemish cuisine). This denatures specifically the elastin and collagen that bundle the muscle fibres together, so that the cooked meat can easily be separated into threads. If you boil such meat at a higher temperature, other proteins form clumps as they denature, making the meat even tougher. Something similar is true for fibrous root vegetables and many kinds of beans. Simmering breaks down the pectin (not a protein), making the cell walls leaky and thereby the veggies soft, up to mushy. Adding a bit of baking soda to the water speeds up the process. --Lambiam 09:21, 4 August 2020 (UTC)[reply]

Thank you @Lambiam. A helpful answer. AboutFace 22 (talk) 00:41, 5 August 2020 (UTC)[reply]

Precipitation of seawater carbonate by enzyme

@Graeme Bartlett: would [1] or [2] be more useful for polymer feedstock? EllenCT (talk) 03:17, 4 August 2020 (UTC)[reply]

Both of these articles are making carbonate salts, first one is making sodium carbonate, and the second, I don't know, but would be a carbonate too. Inorganic carbonates are not useful for making polymers. To make polymer feedstocks, the carbonate needs to be reduced. Perhaps to methanol, ethylene glycol, ethylene or vinyl chloride. So it may have to have some electrolysis going on. Have you checked out our article on carbonic anhydrase? It is speeding up conversion of carbon dioxide to bicarbonate ions. Graeme Bartlett (talk) 06:19, 4 August 2020 (UTC)[reply]

One suggested technique for reducing the impact of global warming is dumping alkali in the sea to trap dissolved carbon dioxide as carbonate rocks. But quite simply crude oil is such a good source for polymer feedstock nothing else is ever going to compete. What we really need to do to stop global warming is stop using fossil fuels to power cars and trucks and ships and electricity: polymer production is such a minimal use of fossil fuels (and so much of it ends up staying as a plastic long-term anyway and not turning into carbon dioxide) it's not a major problem. Wind farms and solar panels are what we need right now. Blythwood (talk) 20:23, 5 August 2020 (UTC)[reply]

Indeed! I am back from abiotic to ocean GMO microbial solutions for the emergency case at present, but some of those abiotic reactors which also desalinate look amazing. EllenCT (talk) 21:01, 5 August 2020 (UTC)[reply]

@Graeme Bartlett: thank you for pointing out the carbonic anhydrase article. I have found more reviews.[3][4]. This is such an exciting area! Please have a look at [5] and [6]. EllenCT (talk) 00:19, 6 August 2020 (UTC)[reply]

Please remember that catalysts don't make possible any impossible reaction but they can only speed up a possible one, and this only in the direction that is currently energetically favorable. That is, if the PH is wrong you cannot obtain any bicarbonate ions from CO2 and water, but instead the catalyst will accelerate the conversion of bicarbonate ions to CO2 and water. But even if you can produce thousands of tons of the enzyme and store billions of tons of water containing your bicarbonate ions after separating them from the catalyst, they are not stable and will quickly free all CO2 again if they are not bound with alkali AND then kept in a cool and basic environment. So I cannot take seriously such claims as in your second link ".. a hybrid system which contain[s] all these CO2 capturing agents will surely prove to be key to mitigate climate change". They didn't name any capturing agent for CO2 in the abstract and CA is surely not one. 2003:F5:6F0C:E600:487C:DA02:59F5:AE62 (talk) 20:49, 8 August 2020 (UTC) Marco PB[reply]

cradle cap

is cradle cap the same thing as seberrhoeic dermatitis? If you have cradle cap as baby does that mean it will stay with you lifelong does it become seberrhoic dermatitis? — Preceding unsigned comment added by 203.219.66.131 (talk) 12:28, 4 August 2020 (UTC)[reply]

It is seborrhoeic dermatitis some of the time: see article cradle cap. It says babies usually get over it in a few months, but sometimes it persists til age 2-3 years. 2602:24A:DE47:BB20:50DE:F402:42A6:A17D (talk) 14:07, 4 August 2020 (UTC)[reply]

Why does someone using a lawnmower outside my house seemingly cause interference on my TV?

Asked by Willy turner (talk) 13:30, 4 August 2020 (UTC)[reply]

It's the high voltage that fires the spark plug. --Guy Macon (talk) 14:20, 4 August 2020 (UTC)[reply]

You can get resistor spark plugs that "incorporates a ceramic resistor to suppress ignition noise generated during sparking". Alansplodge (talk) 14:34, 4 August 2020 (UTC)[reply]

Or get something even quieter? Martinevans123 (talk)

Or for slightly more noise an appropriate grass eating animal is more environmentally friendly. _{may not be allowed in all locations} Sagittarian Milky Way (talk) 19:52, 4 August 2020 (UTC)[reply]

The lawn in question may be a neighbour's. --Lambiam 19:57, 4 August 2020 (UTC)[reply]

... and not necessarily: "Holy cow!" (Batman) Martinevans123 (talk) 19:59, 4 August 2020 (UTC)[reply]

There are also electric and hand lawnmowers, though at least with some hand mowers you have to collect the clippings. And of course an electric motor still has the potential for producing interference, though motors tend to be better-shielded and also don't usually produce the characteristic "bursts" of EMF like spark plugs. They're also better for everyone's health as virtually all gasoline mowers use two-stroke engines which produce lots of nasty pollution. --47.146.63.87 (talk) 21:42, 4 August 2020 (UTC)[reply]

That might be true in the US, but in the UK most non-electric mowers use four-stroke engines, which are a lot less polluting, and quieter. PaleCloudedWhite (talk) 22:30, 4 August 2020 (UTC)[reply]

Ah, didn't know that! Very good! --47.146.63.87 (talk) 00:40, 5 August 2020 (UTC)[reply]

We Brits tend to live a lot closer to each other. Alansplodge (talk) 19:43, 7 August 2020 (UTC)[reply]

To expand on the sciency stuff a bit: a moving electrical charge produces electromagnetic radiation. This can be modeled as waves in the electromagnetic field, and when two waves overlap they interfere with each other. You're presumably watching over-the-air TV, which is also transmitted by electromagnetic waves, and it just so happens that the waves produced by the spark plugs overlap in frequencies with those being used for the TV transmission, producing electromagnetic interference. Another commonplace example of such interference is from microwave ovens. They use microwaves in the 2.4 GHz band. The ovens work by trapping the microwaves inside, but no real oven is perfect and so some microwaves "leak". Because of this, this frequency band is not feasible to restrict usage of to licensed users, but this also means the band is used by many consumer wireless technologies, such as Wi-Fi. Thus, use of a microwave oven can cause interference with these. --47.146.63.87 (talk) 21:42, 4 August 2020 (UTC)[reply]

landing upside down

for an aeroplane, instead of using spoilers, can landing upside down be used, to reduce runway length requirement? assuming landing gear is available on the up side as well. thanks! — Preceding unsigned comment added by 117.219.197.124 (talk) 20:08, 4 August 2020 (UTC)[reply]

What is your theory behind the claim that an upside-down plane would require less runway? --Guy Macon (talk) 21:03, 4 August 2020 (UTC)[reply]

my theory is that lift will be applied downwards by the wings. like done by spoilers.

Why not just have the wings mechanically change shape? You could perhaps utilise technology similar to the flap? That might be preferable to having to flip a plane upside down during landing. Zindor (talk) 01:03, 5 August 2020 (UTC)[reply]

The obvious problem with the proposal is that the plane still requires lift to keep from crashing into the ground until the moment the wheels are supported. Therefore it requires the plane to instantaneously turn upside-down when the wheels touch down. --174.89.49.204 (talk) 01:10, 5 August 2020 (UTC)[reply]

Thrust reversers, which are increasingly used on large aircraft, do something sort of similar but rather more practical. Instead of reorienting the whole craft, they just "point" the engine thrust forwards. --47.146.63.87 (talk) 02:52, 5 August 2020 (UTC)[reply]

The sentence "my theory is that lift will be applied downwards by the wings. like done by spoilers." shows where the OP's thinking went astray. There is nothing magical about reducing lift that reduces runway length requirement, Spoiler (aeronautics) explains that when spoilers are deployed on landing they greatly reduce lift (desirable for other reasons but doesn't slow down the plane) and increase drag (which does help the plane to stop quicker). Landing upside down would not increase drag. It also would not decrease lift! You would still have to orient the plane so that it touches down gently instead of smashing the plane on the pavement. If you don't care how hard you hit, you can reduce the runway length required to zero by flying straight down at maximum speed. There have been zero complaints from anyone who has tried this, but the airports don't like having to collect the scrap metal and then fill in the crater. --Guy Macon (talk) 09:05, 5 August 2020 (UTC)[reply]

how about aircraft carriers? would landing upside down be of any use there? — Preceding unsigned comment added by 117.251.237.158 (talk) 11:51, 5 August 2020 (UTC)[reply]

Same problems as noted by Guy Macon, except this time it is harder to repair a ship under way at sea. --Jayron 32 12:27, 5 August 2020 (UTC)[reply]

Just use a Tailhook, as with landing on an aircraft carrier or an airport equipped for it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:48, 5 August 2020 (UTC)[reply]

thanks! — Preceding unsigned comment added by 117.246.93.181 (talk) 14:51, 5 August 2020 (UTC)[reply]

You may be interested in the flexible deck system, where aircraft were landed wheels-up on a carrier deck covered with layers of inflated fire hoses. Seemed like a good idea at the time. Alansplodge (talk) 17:53, 5 August 2020 (UTC)[reply]

Craig Hosking landed a modified Pitts S2 upside down http://www.hoskingaviation.com/airplaneAction.html There are vids on youtube too TrogWoolley (talk) 22:49, 5 August 2020 (UTC)[reply]

Just so you know, Flight was not a documentary :-). Which brings up another sense of "spoilers", I suppose. --Trovatore (talk) 18:33, 6 August 2020 (UTC) [reply]

Water specific heat capacity by temperature

Is there a place where I can find water's specific heat capacity for different temperatures, let's say 30-100°C? I'm thinking that if a body of a specific temperature is covered with warmer water, there will be some water temperature at which heating thru conduction is exactly balanced by cooling thru vaporization. 93.136.213.247 (talk) 21:58, 4 August 2020 (UTC)[reply]

You may find the article on Thermal conductivity useful. It doesn't have the specific heat capacity of water at different temperatures, but it talks about other factors involved in heat transfer Zindor (talk) 22:42, 4 August 2020 (UTC)[reply]

The NIST page for water has a graph with those heat capacities. --OuroborosCobra (talk) 14:38, 5 August 2020 (UTC)[reply]

Thanks, even better it has an approximation formula! Unfortunately I've realized I need to take into account other factors like water vapor pressure so I don't think I'll get a neat equation in which I can plug numbers and solve. 93.136.199.101 (talk) 19:39, 5 August 2020 (UTC)[reply]

You'd probably get all the data you need from a set of steam tables. I can't point you at one in particular, google gives you many choices. Greglocock (talk) 20:57, 5 August 2020 (UTC)[reply]