Wikipedia:Reference desk/Archives/Science/2020 June 25

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June 25

Plasmapheresis/plasma fractionation and identification of antibodies for the present virus

How does plasmapheresis from recovered individuals from the present virus operate? Does it require plasma fractionation and/or the identification of specific antibodies from this virus? Thanks!--109.166.135.226 (talk) 15:42, 25 June 2020 (UTC)

Antibodies bind to specific white blood cell surfaces, along with other surfaces which the immune system wants the white blood cells to try to eat. They can be extracted from solution using that method, but their molecular weight often falls into a certain range of Daltons, so often blood laboratory centrifuge separation can work too. Identifying antibodies in plasma is a multi-stage process including microscopy, spectograpy, and sometimes fluorescence labeling. 98.33.89.17 (talk) 17:43, 25 June 2020 (UTC)

Effectiveness of disinfectants

What data/research is there re the use of disinfectants against the present virus? Which disinfectant is more effective? How are the effectiveness of disinfectants and the required level of concentration to be effective determined?--109.166.135.226 (talk) 15:53, 25 June 2020 (UTC)

As viruses/bacteria go, the coronavirus family is quite fragile outside of the body, and pretty much any disinfectant kills it on surfaces. Compare this with MRSA, which is really hard to kill.

Surfaces are not the main way people get Covid-19. Disinfecting surfaces helps a little, and washing hands helps a little more, so they are both worth doing, but the main way it spreads is through the air. The way to reduce that is masks, social distancing, and quarantining yourself if you are sick. --Guy Macon (talk) 16:31, 25 June 2020 (UTC)

Just to clarify, it is also not free viruses through the air, it's through airborne water droplets, which is why properly made, but otherwise cheap, cloth masks are actually surprisingly effective in stopping its transmission. Normal breathing puts out a lot of rather large (especially on the molecular scale) droplets (though too small to be visually identifiable) and cloth masks generally have a pore size that stops these fairly easily. This guide describes the current understanding pretty well. The reason why they are much more effective for preventing outbound transmission than incoming transmission is if an infected person breathes out through a mask, the mask minimizes the amount of droplets they put into the air around them. If a healthy person wears the mask, but is around a sick person who isn't, the droplets are still in the air and may collect on all sorts of surfaces around the healthy person, including their hands, face, eyes, exterior of their own mask, etc., all of which carry individually small, but taken in the cumulative rather large, risks for transmission. Proper cleaning and disinfection is part of a good comprehensive mitigation strategy, but the most important part is for contagious people (many of whom may be contagious for several days before presenting symptoms) to wear masks. --Jayron32 18:51, 25 June 2020 (UTC)

"No conclusive studies have been conducted on differentiating between the modes of transmission of viruses via droplets and aerosols; hence, unresolved dichotomy". Transmission of COVID-19 virus by droplets and aerosols: A critical review on the unresolved dichotomy (13 June 2020). Alansplodge (talk) 19:30, 25 June 2020 (UTC)

From the same paper:

"The transmission of droplets and aerosols has significant implications on healthcare workers and caretakers managing patients infected with COVID-19, and providing appropriate PPE is, therefore, of utmost importance. The facemasks play a major role in preventing both droplets and aerosols from transmitting the disease from an infected person to a host."

"Many respiratory viruses are believed to transmit over multiple routes, of which droplet and aerosol transmission paths become paramount, but their significance in transmitting the disease remains unclear. In general, infected people spread viral particles whenever they talk, breathe, cough, or sneeze. Such viral particles are known to be encapsulated in globs of mucus, saliva, and water, and the fate/behavior of globs in the environment depends on the size of the globs. Bigger globs fall faster than they evaporate so that they splash down nearby in the form of droplets. Smaller globs evaporate faster in the form of aerosols, and linger in the air, and drift farther away than the droplets do."

--Guy Macon (talk) 21:56, 25 June 2020 (UTC)

The cold virus (coronavirus) lasts 3 to 12 hours on hard nonporous surfaces. It is an enveloped virus, and is deactivated by alcohols, phenols, aldehydes, chlorine (sodium hypochlorite), and soap. --83.137.6.229 (talk) 08:07, 26 June 2020 (UTC)

Zinc Sulfide

How can you split Zinc Sulfide into its original elements using basic means? UB Blacephalon (talk) 16:55, 25 June 2020 (UTC)

Superheated steam. 98.33.89.17 (talk) 17:39, 25 June 2020 (UTC)

So how would you do that? All this tells me me is that really hot steam is involved. UB Blacephalon (talk) 19:44, 25 June 2020 (UTC)

Step 1: put ZnS in an airtight pressure reactor vessel.

Step 2: add really hot steam until it dissolves.

Step 3: Profit? EllenCT (talk) 20:49, 25 June 2020 (UTC)

Well is there a way to build that because I need to do it DIY style and I don't have one of those lying aroung anywhere. And no its not a profit I'm looking for Its that i want to have a sample of every pure element on the periodic table that I can get my hands on. UB Blacephalon (talk) 21:59, 25 June 2020 (UTC)

How about electrolysis? According to the article, Martin van Marum reduced zinc and antimony salts electrolytically in 1785. --83.137.6.229 (talk) 08:34, 26 June 2020 (UTC)

For these two elements, it will be much easier to just buy them, rather than a DIY compound extraction. Both are easy to buy. Graeme Bartlett (talk) 00:45, 27 June 2020 (UTC)

Hmmm.....Ya you might be right but I do have ZnS just lying around. So there's really no way to extract both of them from it by myself? UB Blacephalon (talk) 03:30, 27 June 2020 (UTC)

Yes, but as reported here Zinc_sulfide Zink and Sulfur react violently releasing much heath, and the product is not soluble in water. All this suggests that both elements are strongly bound in Zinc sulfide. And that means that it takes much energy and effort to separate them again, so there is possibly no way of doing it just by using basic means. 2003:F5:6F09:6700:DCD9:66B6:437B:58AF (talk) 09:29, 27 June 2020 (UTC) Marco PB

Huh? What compounds can I separate using basic means that results in original elements? UB Blacephalon (talk) 13:16, 27 June 2020 (UTC)

Oxygen and Hydrogen can be easily obtained from water for example, with a battery and two wires, also many metals can be obtained from their salts by electrolysis (search "Electroplating"). But some elements like Fluorine and Sulfur are very reactive and are not easily obtained pure with electrolysis because they react with most electrodes and with the other element, so you have to use Gold or Platinum electrodes and to take measures in order to keep the reaction products separated, and this I don't call basic means. In your case you can probably separate on the kitchen table some Zinc as pure element from the sulfide, but it could be ways more difficult to obtain pure Sulfur. 2003:F5:6F09:6700:DCD9:66B6:437B:58AF (talk) 18:00, 27 June 2020 (UTC) Marco PB

Ooh yes. I also have a few more substances lying around like CaCl and litmus powder, but I'm not sure what to do with them, do you? UB Blacephalon (talk) 21:15, 27 June 2020 (UTC)

Fixing ocean carbonate

What is the easiest way to convert carbonic acid in seawater to a solid on a gigaton scale? Can the material be used for seawall construction? 98.33.89.17 (talk) 17:24, 25 June 2020 (UTC)

The easiest way is to reduce atmospheric CO2 concentration, which will cause Q>K on the equilibrium between CO2 and carbonic acid, thus driving the reaction away from carbonic acid formation. Making a building material out of the acidified ocean itself is not easy at all, as nature itself shows. Less acidified sea water will have less bicarbonate than now and more carbonate than now, and it is carbonate that marine organisms use to make calcium carbonate for sea shells and coral. They cannot use bicarbonate nearly as easily. Neither can we. --OuroborosCobra (talk) 18:03, 25 June 2020 (UTC)

Surely there must be an answer to the specific question about the most efficient path from carbonate to solids? EllenCT (talk) 21:01, 25 June 2020 (UTC)

Add calcium hydroxide to the water; turning the carbon dioxide into calcium carbonate before it becomes carbonic acid. The only problem is that calcium carbonate as a wall material is susceptible to erosion (see Cliffs of Dover). Zindor (talk) 21:49, 25 June 2020 (UTC)

A bigger problem could be that the only practical way of producing megatons of calcium (hydr)oxide in the first place is to heat megatons of calcium carbonate to 900 °C (most conveniently by burning a lot of coal) to free exactly as much CO2 into the air as your Ca(OH)2 will ever bind from seawater. The natural source of CaO are the vulcans, and they produce it the same way: by heating calcium carbonate and releasing the CO2 into the atmosphere. 2003:F5:6F09:6700:DCD9:66B6:437B:58AF (talk) 08:40, 27 June 2020 (UTC) Marco PB

• I believe that our article on Ocean storage of carbon dioxide will provide superior answers than the discussion above. --Guy Macon (talk) 22:01, 25 June 2020 (UTC)

No, that's a liquid, not a solid. 98.33.89.17 (talk) 04:17, 26 June 2020 (UTC)

The question is not very practical. A seawall can be constructed cheaper and more effectively by other means than turning seawater into limestone. As User:Zindor wrote, you can neutralize an acid with alkali, this turning it into a salt, like with table salt. --83.137.6.229 (talk) 09:04, 26 June 2020 (UTC)

What other means are less expensive than not having to transport the construction materials to the building sites, assuming there is an abiotic reaction which can be efficiently performed by compact reactors? 98.33.89.17 (talk) 22:47, 27 June 2020 (UTC)

That's just it, though. Your assumption is unfounded. There isn't a cheap and effective way to make limestone out of seawater. It's much cheaper to use other means, including trucking in materials produced elsewhere. --OuroborosCobra (talk) 01:16, 28 June 2020 (UTC)And

Do you know of any sources which actually say that there is no way to create a solid precipitate from the carbonic acid in seawater suitable for seawall construction which is less expensive than using materials shipped in from elsewhere? Or any math in support of that conclusion? 2601:647:5E00:C5A0:1CA3:E185:578A:12C (talk) 16:32, 28 June 2020 (UTC)

• This question is a great example of someone who has never read How To Ask Questions The Smart Way. The OP created a heading and a first sentence talking about fixing ocean carbonate, and only later did those attempting to answer the question find out that what he really wants to do is build a seawall and apparently has zero interest in carbon sequestration. (He may change his tune if the sea level rises and submerges his seawall...   :(   ) He would get a better answer by simply looking at a bunch of seawalls and seeing what they are made of. --Guy Macon (talk) 01:48, 28 June 2020 (UTC)
• Perhaps you can grow some sea grass, mangrove or sea weed nearby. They may take out some of that carbonic acid. If a sandbank builds up in the sea grass, perhaps you will not need a sea wall. Using ultrahigh pressure, you can convert carbon dioxide into diamond and solid oxygen. But given the extreme difficulty and expense involved, the diamond would have better uses than sea wall construction. Graeme Bartlett (talk) 03:26, 28 June 2020 (UTC)

@Graeme Bartlett: I'm hoping to find a chemistry review of the possible brine precipitates of carbonate, with the enthalpies(?) of each. There are dyalytic processes along with, e.g., electrochemical calcareous deposition (which "has seldomly found applications, except for speedup of coral growth, prevention of shore erosion, reinforcement of artificial marine structures and remediation of polluted seawater." Lol.)

Can we use nearby dead corals for the calcium? 98.33.89.17 (talk) 23:23, 28 June 2020 (UTC)

You seem to be impervious to the argument that every tack able to sequestrate some CO2 as a solid generates at least as much CO2 in the process. If you try and use corals as a source of calcium you have to free just as much CO2 from the carbonate as you can bind with your calcium, plus a lot of electricity plus the coral dredging penalty. If you have so much corals at hand, the efficient way is to use them directly as a filling material for you seewalls. Other solutions are hopeless vicious circles that produce ways more CO2 as they can ever sequestrate. If these "dyalytic processes" and similar miracle solutions have never been seriously deployed it is not by hazard. 2003:F5:6F12:6900:114F:CA11:A303:740C (talk) 18:03, 2 July 2020 (UTC) Marco Pagliero

I would like to return this to the questions. EllenCT (talk) 19:32, 6 July 2020 (UTC)

Imunological factors in asymptomatic people

What factors are involved in determining some people to be asymptomatic to the present virus? Are they immunological?-Is it possible by analyzing blood samples from uninfected persons to determine whether they are asymptomatic if infected?-109.166.135.226 (talk) 18:59, 25 June 2020 (UTC)

If you ask someone who is testing positive on a PCR swab test for active viral shedding whether they have symptoms, and they say no, then they are an asymptomatic infection case. The SARS-Cov2 virus often causes no symptoms in infected individuals, perhaps in a majority of cases. We know what causes the likelihood of symptoms, which are comorbid, often pre-existing conditions. Obesity, high blood pressure, diabetes, and advanced age are the big ones I can remember off the top of my head. EllenCT (talk) 20:58, 25 June 2020 (UTC)

And COPD and heart disease. This is a list of maintained by the CDC of underlying medical conditions that pose an increased risk for people of any age. For all we know, remaining clinically asymptomatic while testing positive is not an immunological issue. But much around this disease still remains unknown or uncertain.  --Lambiam 23:28, 25 June 2020 (UTC)

But can an uninfected person know by some test the (virtual?) state asymptomatic or not asymptomatic in the case of a possible infection, but without getting the infection?--109.166.135.226 (talk) 11:30, 26 June 2020 (UTC)

There was a radio report today which said the antibody numbers could be ten times the number of confirmed cases in many regions. 98.33.89.17 (talk) 04:20, 26 June 2020 (UTC)

A link to the report (and radio station)?--109.166.135.226 (talk) 11:32, 26 June 2020 (UTC)

I can't find the exact report I heard, but this is the same story. 98.33.89.17 (talk) 22:48, 27 June 2020 (UTC)

Tunnel boring machines

How do Tunnel Boring Machines scan ahead to areas of ground they’re about to bore to detect services or unexpected ground or other anomalies. 90.194.57.205 (talk) 20:09, 25 June 2020 (UTC)

They do not. The exploration is done before the tunnel boring starts. Ruslik_Zero 20:28, 25 June 2020 (UTC)

In any case, TBMs are only used at depths well below those of any services. Deeper geotechnical investigations are carried out using geological records and boreholes.--Shantavira|^{feed me} 08:08, 26 June 2020 (UTC)

Wishful thinking Shantavira in the case of the London Crossrail tunnelling project:

"Subterranean London is riddled with Tube tunnels, secret passages, Roman ruins, high-voltage cables, long-forgotten aquifers and deep building foundations. The route squirms past these obstacles, passing just 1.5m over the Tube's Northern Line. During the long desk-phase that preceded tunnelling, designers scrutinised yellowed plans for London buildings. For some, they had diagrams of what was actually built. For others, they just had the initial plans. Crossrail's surveyors estimated the size of foundations by examining buildings. Then there was the problem of bombs. 6Alpha [a risk management consultancy] studied records kept by wartime ARP wardens, local authorities, and at times even the Luftwaffe, to identify areas along the route which presented the biggest unexploded ordnance threat. Separate contractors were then sent to survey these areas. So far, no unexploded bombs have been found". Crossrail and Unexploded WWII Bombs Alansplodge (talk) 16:42, 26 June 2020 (UTC)

Due diligence sometimes falls short, as with the Lake Peigneur disaster. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:47, 26 June 2020 (UTC)

My understanding is that generally metro system train tunnels are below archaeology; the JLE certainly was. The big problem is the station entrances, other shafts (ventilation, cooling) and where train tunnels rise up to ground level. And there may be anomalies in the geology: the London Underground, although generally bored through yielding clay, suffers from corrosion where mineral deposits reacted with oxygen in the tunnel to form sulphuric acid, corroding metal tunnel lining. That wasn't even noticed during construction, apparently-it's the kind of thing that would need geotechnical investigation. Probably less important now tunnels are generally lined with concrete. A reverse scenario is when people accidentally drill into a tunnel, which has happened a few times. Blythwood (talk) 03:24, 29 June 2020 (UTC)

Trying to understand the difference between forward-active and saturation modes in bipolar junction transistors

"Transistor#Transistor_as_a_switch" and "Bipolar_junction_transistor#Regions_of_operation" state that the saturation mode is analogous to a switch in the "on" position, and, if I understand what they're saying correctly, allowing current flow between the collector and emitter. Using an online circuit simulator on a website that seems to be on Wikipedia's blacklist, saturation is achieved if both the collector and emitter voltages are the same (-5), and the base voltage is higher/more positive (+5); doesn't this mean that there is no current flow between collector and emitter? ZFT (talk) 22:49, 25 June 2020 (UTC)

Try reading this explanation: [ https://learn.adafruit.com/adafruit-arduino-lesson-13-dc-motors/transistors ]. --Guy Macon (talk) 05:08, 28 June 2020 (UTC)

muscle fatigue (exercise related, not medical)

The muscle fatigue article distinguishes between neural and metabolic fatigue, but doesn't explain how a person recovers from each one, and it's not exactly clear whether neural fatigue limits only muscular force, or also stamina. I.e. is the idea that a novice strength trainer has big enough muscles to lift 200 pounds, but is limited at first by neural fatigue to lifting only 100? Let's say they start out able to lift 100 pounds for 3 repetitions. After a few days, they can lift 100 pounds for 5 repetitions. What has happened--is that an increase in nerve capacity rather than muscle capacity? If they do the 5 reps one day, the next day they might only be able to do 4: whatever has fatigued seems to take a few days to recover. Is that explained somewhere? Are these nerves the ones directly in the exercised muscles, or are they in the central nervous system, so increased arm lifting capacity also increases the ability to leg lift?

Motivation: I'm doing some push-ups as indoor exercise during the pandemic. I'm not obese but I'm out of shape so my rep counts are still pretty low. I'm trying to understand what I'm observing and what to expect if I can keep it up. I'm planning to add some other exercises like stair climbing but haven't done this yet.

Thanks -- 2602:24A:DE47:BB20:50DE:F402:42A6:A17D (talk) 23:49, 25 June 2020 (UTC)

Lactic acid #Exercise and lactate might be relevant, but that article requires a degree in biochemistry to comprehend. 107.15.157.44 (talk) 00:30, 26 June 2020 (UTC)

Do these papers help?

• Neural adaptations to fatigue: implications for muscle strength and training
• Neural Adaptations to Fatigue: Implications for Muscle Strength and Training
• Rethinking CNS Fatigue and Recovery: What’s Really Going On Post-Workout?
• Is Resistance Training to Muscular Failure Necessary?

Note to other experienced Wikipedia editors: When I read the above papers I learned things that I didn't get from our articles. This usually means that [A] our articles need to be improved, or [B] the information is bullshit. Any opinions about which is true in this case? I found a bunch of other non-academic sources, and don't know how to evaluate them. For what it is worth, here are a few:[1][2][3][4][5][6] I have no idea whether what I just read is useful information or a steaming pile of crap. --Guy Macon (talk) 01:21, 26 June 2020 (UTC)

Guy, it is hard to edit articles related to biology or physiology because the MEDRS police go crazy reverting anything but meta-studies if the source or the article is about any topic that could remotely be related to human health. So yeah our articles in those areas are often deficient. 2602:24A:DE47:BB20:50DE:F402:42A6:A17D (talk) 02:58, 26 June 2020 (UTC)

which is a Good Thing, because there are wagonloads of nonce results and crap theories out there, some of which have a circle of devoted followers who'd only be too happy to edit this in.  --Lambiam 09:01, 26 June 2020 (UTC)

No that is crazy, the idea of science is to examine the available information, even though it can be in a malleable state. So when we write about scientific subjects on wikipedia, we should describe whatever info that is out there that has some level of academic recognition. When the topic is something like black hole astrophysics we don't get too much trouble about that. Medical topics are treated a bit specially because we don't want people doing crazy health interventions on themselves: ok fine, do no harm. The problem is some MEDRS goons tend to interpret anything having to do with biology, such as molecular genetics, as medical, which is ridiculous (it is more like astrophysics). Even if it is medical it is ok to relax some of the time. Christiaan Barnard did the world's first human heart transplant over 50 years ago, and wrote a historically important paper about it in a medical journal at the time. The paper has been cited by more than 1000 other papers in the medical literature since then. Our article about heart transplants can't cite that paper under MEDRS, because it is a primary source. We wouldn't want some reader messing up a do-it-yourself heart transplant in their kitchen because they read a famous 50 year old paper by an actual surgeon, instead of a meta analysis with its own potential COI. As a popular youtube tool reviewer likes to say, jeezeless. We are supposed to be here to bring knowledge to people, not keep it away from them. 2602:24A:DE47:BB20:50DE:F402:42A6:A17D (talk) 10:06, 26 June 2020 (UTC)

(a) WP:MEDRS is a content guideline, not policy. (b) It is recognized that sometimes improving Wikipedia requires making exceptions – which should not be appealed to on a regular basis as a way to navigate around the rules, but only occasionally because exceptional circumstances justify it. This may then give rise to a dispute, but we have ways of peacefully resolving such disputes. See also Wikipedia:Why MEDRS? If you have issues with the guideline itself, I suggest you bring them up at WT:MEDRS. If your objections are with the rationale, raise them at Wikipedia talk:Why MEDRS?  --Lambiam 13:14, 2 July 2020 (UTC)