Wikipedia:Reference desk/Archives/Science/2016 October 30

= October 30 =

Glass frit filters
Is it possible to obtain a glass frit filter plate alone, without the funnel? Or alternatively, is it possible to remove the filter plate from the funnel without irreparably damaging the item (i.e. in such a way that it would be possible to put the plate back in again as before)? 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 06:15, 30 October 2016 (UTC)
 * What's wrong with this &  or I think  &  too? Nil Einne (talk) 12:43, 30 October 2016 (UTC)
 * Cool! That's precisely what I was looking for! 2601:646:8E01:7E0B:998F:4012:900C:F798 (talk) 21:32, 30 October 2016 (UTC)

How do lungs cleanse themselves from dust buildup
Does all the dust and other particles that come with breathed air build up somewhere in the organism? If so, how do lungs or respiratory pathways cleanse themselves from such deposits? I know that nasal mucus catches some particles, but I don't think it's enough to prevent dust accumulation somewhere in the respiratory system in one's lifetime. Thanks.--93.174.25.12 (talk) 14:15, 30 October 2016 (UTC)


 * The two possibilities would be coughing it up and either swallowing it or spewing it from the mouth (see mucociliary clearance), or the body absorbing those particles over time, through the lung walls: . However, in some cases, such as chain smokers, the particles may indeed accumulate faster than they can be removed: . StuRat (talk) 14:20, 30 October 2016 (UTC)


 * In humans, we have a process called mucociliary clearance, in which our cilia cells that line our respiratory tract convey foreign particles out of the lung. Once again, our article cites numerous studies with further information on the effects of dust, particulates, and even cigarette smoke.
 * Nimur (talk) 14:30, 30 October 2016 (UTC)


 * Thank you for updating your post with corrections and citations, StuRat. Nimur (talk) 14:51, 30 October 2016 (UTC)


 * No corrections, only clarifications and citations. StuRat (talk) 17:23, 30 October 2016 (UTC)


 * StuRat is correct. For example, see this paper regarding inhaling diesel exhaust which states that "Soot-adsorbed BaP was rapidly absorbed when deposited and desorbed on the alveolar air–blood barrier in a process not likely different from absorption of instantaneously dissolving microcrystals of BaP (42). The faster rate of absorption of crystalline BaP compared to soot-adsorbed BaP may reflect the difference between instantaneous dissolution of BaP crystals in the lungs and the decreasing desorption rate of BaP from the soot surface", emphasis mine. In addition, soot particles were found in the alveolar lymph nodes after 5.6 months (assumed to be transported there by the lung's macrophages).   Here is another example of particle absorption, in this case, it's a study of the rapid absorption rate and the high bioavailability (>80%) of vapor particles of pure drugs,  .  --Modocc (talk) 14:42, 31 October 2016 (UTC)


 * StuRat may or may not be correct. However if it's true their post doesn't provide sources to support their claim, their post is still incorrect. If someone else is able to provide sources to support their claims, that's great, but this could be prevented by providing sources to support their claims, especially when asked. While I make no comment on whether the sources provided by StuRat do support the claims made, I note that sources should generally describe what is claimed rather than just being based on the title and/or an interpretation which may be incorrect. Notably as mentioned below, there could easily be a difference between drug molecules which are generally relative small, and dust or other things likely to be called particles which is a term that StuRat used. Even if there happens to be no difference, it doesn't mean there's anything wrong with pointing out that the source doesn't actually support the claim if it's talking about something else. Note again I haven't actually looked at the sources StuRat provided, so I can't be sure the claims below are correct, but they do seem compelling. Nil Einne (talk) 00:23, 1 November 2016 (UTC)


 * Adding citations to a post without any [//en.wikipedia.org/w/index.php?title=Wikipedia:Reference_desk/Science&diff=prev&oldid=746945205] is indeed a correction to a majorly flawed post on the reference desk. Sorry this is still a surprise to you, but we do have standards here even if some people regularly don't meet them. Nil Einne (talk) 23:16, 30 October 2016 (UTC)


 * No, a correction would be if I removed an incorrect statement. I did no such thing.  I clarified, and added citations, just as I said. StuRat (talk) 00:53, 31 October 2016 (UTC)


 * Well then you have a definition of correction that is out of step with most of the rest of the world. Your post was simply unacceptable/incorrect initially. It lacked the basic pre-requisites needed to make it suitable answer to the question or for that matter an acceptable post to the RD. You attempted to correct this. There is some suggestion you failed spectacularly. I make no comment on this part. But for this reason it may be more accurate to call it an attempted correction rather than a correction, but either way, that's what most of the world would call it. Likewise if someone hands in an assignment/report/whatever which is majorly flawed perhaps because it lacks sources, the person who fixed this is indeed correcting what they initially handed in. They're not going to get far by claiming they were simply clarifying major flaws in what they initially handed in. Nil Einne (talk) 23:56, 31 October 2016 (UTC)


 * No, you are the one using the unusual definition of "correct". See wikt:correct, definition 1.  A statement may be correct (true) or incorrect (false), regardless of whether it is referenced or unreferenced.  All 4 combinations are possible.  You seem to primarily value that an answer be referenced, with little value placed on it being true or not.  Here I disagree.  Being true is more important than being referenced.  And, as Modocc has since confirmed, with additional sources, my answers were true.  I also don't buy that you equally review all contributor's sources.  Let's see some of your critical reviews of other contributor's sources, please.  (To use your own logic, your statement is incorrect, because you have failed to provide refs to prove it.  And, even if you later do provide such sources, the original statement will still have been "incorrect".) StuRat (talk) 19:33, 1 November 2016 (UTC)


 * ? I've read through the Heyder article and find no mention of particles being absorbed through the lung walls.  A text search for "wall" yields only "multiwalled carbon nanotubes" and there are no hits for "absorb".  There is a single clause mentioning "drug delivery to the systemic circulation", which I suppose would involve a drug molecule (not necessarily a particle) crossing the lung wall.  Have I missed something?--Wikimedes (talk) 19:30, 30 October 2016 (UTC)


 * I concur - not in citation given. We've made a little progress - it's better than no citation, which was the original post - but I also do not find the statement in the full article that StuRat linked.  Nimur (talk) 21:37, 30 October 2016 (UTC)


 * I hate to pile on here, but it was only 5 days ago at "Why are evolutionary the testis are located outside of the body?" that StuRat similarly used a source that did not actually contain the content he claimed., you must realise that using sources in this way is disruptive because other editors are having to repeatedly fact-check your postings.  Please try to raise the standard as this is a REFERENCE desk. DrChrissy (talk) 23:41, 30 October 2016 (UTC)


 * The linked article is titled "Deposition of Inhaled Particles in the Human Respiratory Tract and Consequences for Regional Targeting in Respiratory Drug Delivery". In that context, it's clear that they are talking about inhaled particles of medication which are absorbed into the lungs.  If you're going to nitpick every source to this degree, I might be better off not listing my sources.  StuRat (talk) 00:50, 31 October 2016 (UTC)


 * We are going to nitpick every source - posted by every person. If you aren't comfortable having your contributions subject to the same heavy scrutiny as every other Wikipedia contributor - including the demand for reliable citations, which we will scrutinize, then this encyclopedia isn't the place for you.  We can direct you to other internet forums where the discussion tenor is more informal.  Respectfully: you may fix your post, or you may remove your post, but it is unsuitable as it stands at this time.  Nimur (talk) 13:53, 31 October 2016 (UTC)


 * It seems to me this could easily be resolved if you could provide some evidence in the form of quotations from the source you provide, that demonstrates they are indeed referring to particles about the size of dust or similar as you repeatedly assert, rather than as suggested by Wikimedes simply drug molecules which tend to be small. If it's so clear, this should be a simple task. After all, it seems like Wikimedes has already taken the effort to skim through the source, and I assume you at least did the same before providing it which is what lead you to believe it supported the claim. Nil Einne (talk) 00:28, 1 November 2016 (UTC)


 * I never doubted that soluble particles would be absorbed at different rates due to dissolution and make it past the barrier (thus not be expelled), and so I choose to read StuRat's answer regarding any absorption of "all the dust and other particles that come with breathed air" (as stated by the OP) as being relevant. Furthermore I found evidence per my citations that insoluble particles are absorbed too. But to ice this question regarding particle sizes, ultrafine particles get past the barrier --Modocc (talk) 00:47, 1 November 2016 (UTC)


 * Good finds Modocc. Nil Einne's reference below posted 14:25, 30 October 2016 also mentions that particles in the lungs can be absorbed into the bloodstream.  (And if the particles are dissolved first and then absorbed as individual molecules, that still counts as being absorbed IMHO).  The question of whether or not StuRat's reference supports particle absorption through the lung wall has been made irrelevant, at least in terms of answering the original question - no need to pursue that distraction any further.--Wikimedes (talk) 07:58, 2 November 2016 (UTC)


 * I had thought that asbestos got absorbed through the lungs, but apparently not. This specifies that they may only lodge in the lungs (not that that is a good thing), and that they may get absorbed by the digestive tract if the particles are coughed up and swallowed. Matt Deres (talk) 22:03, 30 October 2016 (UTC)


 * There's some discussion here Nil Einne (talk) 14:25, 30 October 2016 (UTC)


 * The lungs contain alveolar macrophages which engulf anything foreign that makes it into the alveoli. (That article needs a lot of work.) --47.138.165.200 (talk) 02:54, 31 October 2016 (UTC)


 * The alveolar macrophage digest the particles. Undigested soot particles do get transported into lymph nodes and remain there for months according to and I've not found a reference for what happens to those soot particles and any additional phagolysosomes long term.  According to the articles I've read thus far, lymph is returned from the lymph nodes to the veins of the cardiovascular system, thus I would guess that a significant portion of the soot they found slowly ends up in the bloodstream and is then subsequently filtered by the kidneys and excreted (again, I've no source saying exactly that though).  --Modocc (talk) 16:22, 31 October 2016 (UTC)

Fetal pain at 13 weeks
Is there any evidence that fetuses are able to feel pain at 13 weeks gestation? I read the story of one former employee of Planned parenthood who said she witnessed a fetus squirming around as it was being aborted.Uncle dan is home (talk) 23:53, 30 October 2016 (UTC)
 * Prenatal perception seems fairly clear the answer is no. As for later in the pregnancy, if you're having trouble understanding parts of the article, perhaps this will help . I can't seem to find any good sources discussing such videos that you mention in all the junk, hopefully someone else will. But in the interim, consider that when I touch my cat he will respond in vaious ways, even though I try to avoid causing pain and think I succeed most of the time. Point being, even if there is a reflex response let alone a conscious response, it doesn't mean either are because of anything remotely similar to pain. If someone is claiming something is a response to pain, you have to ask them what evidence the have fo the claim. Nil Einne (talk) 00:24, 31 October 2016 (UTC)
 * I find it useful to consider how the brain develops. Clearly there can be no "pain" before the neurons develop and connect to each other.
 * [ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2989000/ ] has some numbers:
 * "The formation of the neural tube occurs between E19 and E29" (E19 means the 19th day since conception)
 * "Neuron production begins in the embryonic period on E42"
 * "In humans cortical neurogenesis is complete by approximately E108"
 * If the question is important to you, I would suggest reading several scientific papers on early brain development. --Guy Macon (talk) 10:28, 31 October 2016 (UTC)
 * Pain in babies also contains some information on prenatal pain in fetuses. References #2 and #5 seem relevant here.  -- Jayron 32 10:37, 31 October 2016 (UTC)