Wikipedia:Reference desk/Archives/Science/2014 September 21

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September 21

Paper and water

Why is ordinary paper damaged so significantly by getting even a little bit wet? It's not simply the fact that water causes damage, but paper exposed to very tiny quantities of water can be impossible to restore to anything like its original condition. Peter Grey (talk) 03:54, 21 September 2014 (UTC)

I think you'll find that paper based from pulp wood is much more easily damaged by water than is high-quality rag-bond paper. Dunk a dollar bill in water and I think you'll find that it recovers quite nicely. ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:08, 21 September 2014 (UTC)

If you read the papermaking article it says "In paper-making, a dilute suspension of fibres in water is drained through a screen, so that a mat of randomly interwoven fibres is laid down. Water is removed from this mat of fibres by pressing and drying to make paper". If you add water back to the paper you are reversing the process and turning back into paper pulp. This causes the randomly aligned fibres to expand in different directions, which causes the flat sheet of paper to buckle. To get it back to a flat piece of paper you would have to repeat the original process by drying it and rolling it out again. In practice this would be impossible to do whilst preserving the integrity of anything printed on the surface. Richerman (talk) 08:56, 21 September 2014 (UTC)

Thermite torch

There's this clip of MacGyver on YouTube which shows him creating a "termite torch" by mixing magnesium shavings with rust in a pipe and then igniting it with a road flare. Is this possible? I know there's something called a thermal lance, but that seems to be slightly different. It's using iron rods packed into an iron rod and then injects the rod with oxygen while this device that MacGyver uses seems to just be ignited thermite in a tube. ScienceApe (talk) 06:49, 21 September 2014 (UTC)

A Sparkler mixes ingredients like this for fireworks. Not sure what rust would do except color (temperature control?) --DHeyward (talk) 07:13, 21 September 2014 (UTC)

The rust provides the oxygen. Rust is not s single material (water and oxygen can combine differently with iron to make rust), but one possible reaction is 2Fe₂O₃+6Mg -> 6MgO+4Fe. Magnesium yields its electrons easier than Iron, so that should be an exothermic reaction. Of course, I don't know if many road bikes are really made from magnesium (aluminium seems to be a lot more common), and the MacGyver version is, as always, a bit cinematic. But I seem to remember that Pashtun gunsmiths in Afghanistan used a mixture of rusty scrap metal and magnesium in a crucible to produce molten steel for casting gun parts. --Stephan Schulz (talk) 09:21, 21 September 2014 (UTC)

There's one or two errors in the film clip. Thermite is normally created using aluminium and rust. Magnesium is possible but less common. Bicycles are very rarely made from magnesium, and those that are are cast. They are now commonly made from aluminium. The one shown was steel. You can't put out a thermite reaction by touching the torch on the ground. It supplies its own oxygen and so taking away the oxygen like that would have no effect. Aprart from that, it's all quite feasible.--Phil Holmes (talk) 12:56, 21 September 2014 (UTC)

Pretty amazing, a thermite reaction inside a metal pipe that doesn't melt the pipe itself... Ssscienccce (talk) 19:48, 21 September 2014 (UTC)

Bioluminescent Dinoflagellates

Do you think it is possible to farm bioluminescent dinoflagellates at home? What equipment could such farming require? 85.141.226.92 (talk) 15:50, 21 September 2014 (UTC)

So, you want glowing plankton that kills people? μηδείς (talk) 17:16, 21 September 2014 (UTC)

The question is hypothetical. Also I as far as I know not all dinoflagellates are toxic, aren't they? And shouldn't they be eaten first to harm the human body? 83.237.120.61 (talk) 18:06, 21 September 2014 (UTC)

I swam in a bioluminescent bay in Vieques, Puerto Rico, on an organized excursion, and was exposed to these little dinoflagellates as are thousands of tourists a year. They were said to be harmless. When a fish swam through them, they would leave a light streak to mark the passage. If you moved in the water, they lit up. Visitors doubtless consumed some of them while in the water. Their colony was said to be very fragile, and the guides (who were licensed/authorized/accredited) said that in a different bioluminescent bay, misguided attempts to improve their habitat had exterminated them. Guides said that they were worried about proposed resort construction, since the critters seem to expire when there is a lot of artificial light. In sum, I doubt it would be easy to farm them, but research about what conditions allow their survival would be of value. Edison (talk) 21:30, 21 September 2014 (UTC)

Unknown Insect

I found this insect tonight. It behaves like a fly but it seems unusually large and colourful for urban England. Any ideas what it is?

Matt's talk 22:01, 21 September 2014 (UTC)

I've fixed the formatting on your links. No idea about the insect, I'm afraid. Tevildo (talk) 22:27, 21 September 2014 (UTC)

Thank you. I tried using the new snazzy markup tool but it wasn't a success. Matt's talk 22:47, 21 September 2014 (UTC)

Looks like a Horsefly to me, but I have no idea on the specific species. --Jayron32 22:31, 21 September 2014 (UTC)

Definitely a true fly, i.e. a member of the diptera ('two wings') - while most insects have four wings, flies have two wings and two little stubs called halteres. If you look closely in the photos, I think you can see the halteres. Other key features are the large eyes and sucking mouthparts. SemanticMantis (talk) 13:54, 22 September 2014 (UTC)

Agree with horsefly. See Horse flies, clegs & deer flies. They bite like a mosquito only bigger, their only saving grace is that they're a bit slower to fly away than a midge or mossie and so they're easier to swat. Alansplodge (talk) 12:18, 23 September 2014 (UTC)

binding profile quetiapine

Dear ladies and gentlemen,

at the following URL-Adress, there is something wrong.

Quetiapine On your website, there ia a table with the binding-affinity to some receptors.

When I look at the canadian database - http://www.drugbank.ca/drugs/DB01224 there I can see, that in your table are missing following receptors:
Alpha adrenergic 2B,
5HT1B,
5HT1C,
5HT1E;

Maybe you can give me the information, where I can get a better table. By - www.drugbank.ca/drugs/DB01224, there a only the receptor-type, but no binding-affinity (Ki-value)

And maybe you can look too for a save and better Ki-Table for Halperidol, Olanzapine, Risperidon.

And sorry, one more question. This metabolit norquetiapine - the value in the table - is this an antagonsit too? Can I add the first value from quetiapine with the second value from norquetiapine to get the atagonism together for this receptor? for example:
5-HT2A Quetiapine: 118nM Norquetiapine: 48nM --> together: 166nM Antagonist ?

And maybe you can answer this question:
This is in the table on your side
NET Quetiapine: >10000nM Norquetiapine: 12nM
When I say, I only look for this value 12nM, then I have a big effekt to the NET-/NAT-transporter.

How large is thus the opposite effect to antagonism of adrenergic receptors.

For example - the average Ki-value of all adrenoreceptors is 36nM. The opposite effect by blocking norepinephrine reuptake is accomplished by 12nM on the NET-transporter. Is there a way these two opposite effects to count against each other? Are there any estimates how to do this?

thank you very much for your help.

Dai Dirtd Germany — Preceding unsigned comment added by Dirtdai (talk • contribs) 22:12, 21 September 2014 (UTC)