Wikipedia:Reference desk/Archives/Science/2016 January 8

= January 8 =

argh! what is the standard industry term for this kind of plug?
I'm looking at this 12 V DC 1 A power supply which takes in AC input. Critically, the product features this tiny accessory which converts the "laptop-style" 12V DC plug into two +/- screw terminals. What is the standard industry term for this type of accessory or plug? (The inverse version -- male barrel plug, female screw terminals is here ) My main motivation is to power this 12V vacuum motor to help with Buchner flask extractions. However, I don't know how I'm supposed to solder a 12V connection onto a screw? I'm just trying to find out more about these "screw terminals". Yanping Nora Soong (talk) 00:50, 8 January 2016 (UTC)
 * The screw terminals are designed to screw down onto a pair of wires. They are not designed to solder. There would be different power sockets designed to solder to a board. Graeme Bartlett (talk) 01:47, 8 January 2016 (UTC)
 * What's the industry term for this kind of terminal? I still can't find articles for it. More importantly, how do I secure wires onto the screw? Do I have to tie down the individual filaments on the wire around the screw? That seems kind of hard. Yanping Nora Soong (talk) 04:22, 8 January 2016 (UTC)


 * The type of connector that you called "laptop-style" is called a coaxial power connector. The "accessory" you referred to is an adapter converting one type of connector to another. You can see the screw terminal end of the adapter more clearly in the pictures on these pages: and . --98.115.39.92 (talk) 05:04, 8 January 2016 (UTC)


 * To use the screw terminals, undo the screw a bit. Insert a wire stripped for a short distance into the jaws, and then screw the screw down till it has a good grip on the wire. Do this also for the other wire. Graeme Bartlett (talk) 05:16, 8 January 2016 (UTC)
 * As no-one's linked it yet, the technical term is screw terminal. Tevildo (talk) 08:51, 8 January 2016 (UTC)

Does eggs contain (free) H2O?
I'm asking this question because always when I fry eggs I see vapor raises from the frying pan.92.249.70.153 (talk) 03:41, 8 January 2016 (UTC)


 * Yes. Our article, egg white § Composition cites a source, stating 92% of the egg-white (the liquidy part of a chicken egg) is water, by mass.  Similarly, our article on yolk, § composition, states that the yellow part contains lots of fats and oils, by mass; but there are some trace other compounds; and about 50% of the yolk is water.  Nimur (talk) 03:59, 8 January 2016 (UTC)
 * Half of the water in the yolk is water? ←Baseball Bugs What's up, Doc? carrots→ 04:09, 8 January 2016 (UTC)
 * Sorry, I had a typo in my comment; I removed it. Nimur (talk) 04:26, 8 January 2016 (UTC)
 * Interesting, thank you. 92.249.70.153 (talk) 06:40, 8 January 2016 (UTC)

World's lowest maximum voice
I was trying to search on bing about the world's quietest maximum voice but I couldn't find it. I'm thinking that the world's weakest maximum voice would be so feeble that it can barely hear it even when putting one's ear right beside person's mouth in a quiet room. In order for the person who has that feeble voice to be heard when talking verbally to people from a distance, it would need a microphone or an amplifier that can put in the mouth that can amplify the voice a thousand times to have the normal vocal range in loudness. Planet Star  04:38, 8 January 2016 (UTC)
 * Is there a question? Double sharp (talk) 10:17, 8 January 2016 (UTC)
 * I just commented about it to see how anybody would think. Planet  Star  00:39, 9 January 2016 (UTC)
 * You may pursue your search in Wikipedia, starting at the links shown in List of language disorders. Dysphonia is the medical term for disorders of the voice, distinct from Aphonia where speech is impossible. Voice pedagogues define voices in terms of their musically useful Vocal range of singing pitch, which for a given singer differs depending whether the context is opera where singers must project over an orchestra without the aid of a microphone, or pop songs delivered in a recording studio. Two extreme voice modes are shouting where a 129 dBA audio level was set by a human in 2000, and Muteness the inability to speak which can be due to a variety of Speech disorders. Since anyone can deliberately reduce their speaking volume it seems unreal to identify anyone as posessing the world's quietest maximum voice. A typical electric Megaphone can provide 1000x sound power amplification i.e. 30 dB (decibels). In a crowd address situation this can enable each of 1000 listeners to hear the speaker as though they were about 1 m distant (see Sound power, Sound pressure). AllBestFaith (talk) 11:27, 8 January 2016 (UTC)
 * I was thinking that many cases of faint maximum voices are caused by voice disorders. Planet  Star  00:39, 9 January 2016 (UTC)

Is it true that ethnic Swedes will be a minority by 2050?
Read somewhere else that it's by 2041. 2.102.185.25 (talk) 05:12, 8 January 2016 (UTC)
 * They are a minority now - depending on whom you count, there are between 8 and 13 million Swedes, out of about 7.3 billion humans. --Stephan Schulz (talk) 08:54, 8 January 2016 (UTC)
 * I was thinking to ask the OP, "In which country?" It might be the case that there are more "ethnic Swedes" in America than in Sweden. ←Baseball Bugs What's up, Doc? carrots→ 09:04, 8 January 2016 (UTC)
 * Swedish Americans says there are 4.3M Americans of Swedish ancestry, which is definitely less than the 7.6M Swedes in Sweden. Dragons flight (talk) 09:32, 8 January 2016 (UTC)


 * I believe the poster is referring to the anti-immigration rhetoric in Sweden. From 2010 to 2014, the percentage of Swedish residents with "Foreign background" (defined as foreign-born or Swedish-born with two foreign-born parents) has increased from 19.1% to 21.5% according to official statistics .  Alarmists extrapolate this 2.4% growth over four years (and similar statistics) to conclude that in several decades Sweden will be majority foreign.  Of course, such extrapolations from a few years of data are rather crazy.  I believe the official projections assume the foreign population stabilizes at around 25%.  It is also worth keeping in mind that almost 2/3 of the "foreign background" residents have already become Swedish citizens.  Dragons flight (talk) 09:24, 8 January 2016 (UTC)


 * I think the definitions are the toughest part of these things. At least in the U.S., black x white = black, Hispanic x anything = Hispanic.  So unsurprisingly enough, the number of blacks and especially Hispanics steadily rises.  Short of banning miscegenation there is no way to stop that.  But it doesn't actually mean anything. Wnt (talk) 14:23, 8 January 2016 (UTC)


 * Likewise, in any country, you tend to find the ultra-right-wing nationalists tend to define "true X" as "All X ancestors since time immemorial; that is the xenophobic nutjobs who care about these things would say (in this case), "A true Swede is someone whose family has always been pure Swedish", as if you had to trace your ancestry back to Odin to be a "true Swede". See, of course, no true Scotsman for the problem with such thinking, along with the mythos that ethnicity is fixed and immutable over time.  -- Jayron 32 16:09, 8 January 2016 (UTC)
 * Actually, there have been no true Swedes ever since the Vikings brought back Slavs and Celts and Anglo-Saxons to serve as thralls and polluting the blood line. And even Ragnar Lodbrok was originally from African stock. --Stephan Schulz (talk) 17:10, 8 January 2016 (UTC)


 * Lots of well-meaning obscurantism in this thread. Asmrulz (talk) 21:57, 8 January 2016 (UTC)
 * Actually, Dragons flight and Wnt seem to have answered the OP's question with no obscurantism at all. Ethnic Swedes are only a majority in Sweden now, as Dragons Flight pointed out.  And wnt brought up the parallel issue here in the United States of when Caucasians cease being the majority ethnic group. He's absolutely right that it doesn't mean anything - except, of course, for those on the right and left political wings here for whom racial identity is more important than every one of us being an American.  That includes the many, many people you see in Denver driving around in pickup trucks on Cinco de Mayo with huge Mexican flags in the hands of several inebriate friends. loupgarous (talk) 06:56, 10 January 2016 (UTC)

Does the stroke volume of the right ventricle equal to the left ventricle (heart)?
I have heard many opinion and I would like a reliable source about that. Thank you 92.249.70.153 (talk) 06:39, 8 January 2016 (UTC)
 * Our article on stroke volume defines the term as "the volume of blood pumped from the left ventricle of the heart of the heart per beat." So the term "stroke volume" has no meaning applied to the right ventricle's output.  I was medical writer for a cardiology research clinic for a few years, and this is the same understanding I had working with several cardiologists and technicians who dealt with the concept of stroke volume many times a day. loupgarous (talk) 07:12, 10 January 2016 (UTC)

Does the right and left ventricle have the same BPM?
I'm reading the article Ejection Fraction here, and I got confused when I saw this table. It's not clear for me (when I see the information on this table) if the right and left ventricle have the same BPM, because it's written there that the right side has 75 bpm while the left side has 60-100 bpm (there is no source) and it doesn't make sense to me because according to what I know the impulse of the sinus make a depolarization for the both of the ventricles at once. I would like to check it out with you, thank you 92.249.70.153 (talk) 06:52, 8 January 2016 (UTC)


 * The mean volume must be close to identical because the same volume must pass through the two halves of the same circuit. This does not meant that each stroke must be identical. There will also be slight differences in the mean volume as some plasma leaves the blood circuit as lymph and does not get reintroduced identically. If one ventricle comes up a bit short on one stroke, the resultant blood volumes in the vessels will tend to help balance the mean volume on the next stroke through preload and afterload effects.
 * The mismatch in beats per minute on the table in ejection fraction may be a difference in measurement conditions, not a mismatch in an individual's ventricular rates (which as noted above, would make no sense). I'd have to dig into the table to figure out the details. BiologicalMe (talk) 16:47, 8 January 2016 (UTC)

Nobel prize nominee but never won
Can I get a list of people who were nominated for Nobel prize, but don't have an article yet. Is there any website which can show the persons who are capable of getting Nobel Prize in future? --Marvel Hero (talk) 07:24, 8 January 2016 (UTC)
 * I seem to recall, from a discussion here a good while back, that nominees are not officially known to the public. So any information on the subject would be anecdotal or speculation. ←Baseball Bugs What's up, Doc? carrots→ 07:27, 8 January 2016 (UTC)
 * Not exactly. The records of the Nobel Committee are released 50 years after the fact.  So one can browse the nomination archive .  I don't know of any lists that explicitly state nominees that never won, but one could make such a list for the time periods when records have already been unsealed.  Dragons flight (talk) 07:49, 8 January 2016 (UTC)
 * That doesn't answer the second half of Marvel Hero's question, because that asks "Is there any website which can show the persons who are capable of getting Nobel Prize in future?" Peter Higgs is the only person I'm aware of who went anything like 50 years from publication of the work for which he earned the Nobel Prize (1964) to actually getting the prize (2012). I'm skeptical that such a website (of potential future Nobel laureates) exists. loupgarous (talk) 08:05, 10 January 2016 (UTC)

Science awards
After Nobel prize, which science awards are most internationally recognized? I need general views, not perfect rankings. --Marvel Hero (talk) 07:46, 8 January 2016 (UTC)
 * From the fields that are not covered by Nobels, I'd say the Fields Medal for mathematics and Turing Award for computer science. We do have List of prizes known as the Nobel of a field. --Stephan Schulz (talk) 13:04, 8 January 2016 (UTC)
 * Stephan Schulz your answer was helpful. And I would also like to know the others which are reputed but next to Nobel, including Physics, Chemistry, Biology, Medicine. As FIFA World Cup is the best among football. After that comes UEFA European Championship. Likewise I want to know about those awards given to scientists which are considered second-best after Nobel prize (any field). --Marvel Hero (talk) 13:23, 8 January 2016 (UTC)
 * I find your lack of faith in Copa América disturbing. :)Naraht (talk) 22:10, 8 January 2016 (UTC)


 * I would mention the MacArthur Fellows Program as one of the more well-known recognition programs that covers broad topics (not just science though). Dragons flight (talk) 13:13, 8 January 2016 (UTC)


 * You can also locate the more prominent societies and organizations: for example, representing Physics in the United States is the American Physical Society, who host a series of prizes, honors, and awards. The same applies to other fields and other geographic regions.  There are also more broad organizations, like the American Academy of Arts and Sciences; induction into AAAS as a fellow is a prestigious opportunity offered only to a select few researchers and scholars.
 * There are also political awards, like the National Medal of Technology and Innovation and even the Presidential Medal of Freedom, or the wide array of equivalent honors bestowed in other countries. These types of awards are widely publicized and well-known; but they are arguably less an accolade of pure technical accomplishment, and often connote some accomplishment that benefits society at large.
 * More locally, my old school confers the honorary title, Engineering Hero, to a very select few contributors whose accomplishments have "profoundly advanced the course of human, social and economic progress through engineering." I'm not too sure how widely known this accolade is, but the recipients have usually been world-famous!  You can probably find similar awards, ranging from medals to titles to honorary doctorates.  At what point does such an accolade qualify as "internationally-known"?  Does "international repute" necessarily entail using a lot of money as the prize-incentive?  If so, even a third-tier venture-capital awardee probably has received more prize-money than the Nobel in recognition of some quasi-technical accomplishment!
 * On the whole, Nobel Prizes and Fields Medals are the big ones - those are recognized widely by people who aren't scholars or subject-matter experts. All the other awards that have a lower profile tend toward enhancing recognition within a particular audience.
 * Nimur (talk) 14:47, 8 January 2016 (UTC)

hazards of abandoned buried electrical cables
With respect to this article, can anyone figure out whether the abandoned electrical cable was still energized, and if not, how it caused such an explosion? —Steve Summit (talk) 15:23, 8 January 2016 (UTC)


 * The article, Salty Brine State Beach, links to one news story, from the Providence Journal, July 2015, that says the electrical cable was deenergized and unrelated to the explosion. This isn't conclusive to me, but it may point toward better sources or investigation reports.
 * The news report follow-ups cite statements and reports from the Rhode Island Department of Environmental Management. That's where I would look for more documentation.  The present theory is that copper, in contact with salt water, somehow corroded and evoked hydrogen gas, which became trapped and eventually ignited.  This theory leaves room for more questions, but at least you have a few places to look.
 * More sources:
 * Press Release from ri.gov
 * Slide presentation: Probable Cause..., presented by URI Graduate School of Oceanography
 * University of Rhode Island faculty interviewed on Rhode Island Public Radio.
 * Something still has to provide ignition, in order to complete the fire triangle; and something has to provide current for electrolysis in order to produce hydrogen in the first place; but metal in contact with salt water is in itself a Galvanic cell, so that really might be all there is to this story.
 * Nimur (talk) 15:43, 8 January 2016 (UTC)


 * Thanks. I'm having a hard time believing that enough hydrogen could have been, er, generated to cause that big an explosion, but (a) stranger things have happened and (b) my intuition about anaerobic chemistry is nil. —Steve Summit (talk) 15:57, 8 January 2016 (UTC)
 * The key is trapped gas - a low concentration of hydrogen becomes a higher concentration over time; and then, you have a confined combustion, which turns a deflagration into a detonation. According to the report hydrogen will burn at 4% in air, and detonate at 20% concentration - at ordinary atmospheric pressure.  When trapped, in an unknown environment with unknown mixtures of other materials, with unknown total- and partial- pressures, we can only guess: hydrogen detonates at a concentration somewhere between "0%" and "100%".
 * It takes very little fuel to produce a massive explosion. The keys to powerful explosions are oxidizer and confinement.  This is one of many good reasons why certain other reference desk contributors, who shall remain unnamed, really need to stop playing kitchen-chemist in their apartment building.
 * Nimur (talk) 16:01, 8 January 2016 (UTC)
 * Well, that depends on what you mean by "massive" and also by "powerful". The maximum energy release is limited by the amount of fuel, at least. --76.69.45.64 (talk) 20:47, 8 January 2016 (UTC)
 * Indeed, but my point is that a very small amount of fuel can carry a very large amount of chemical energy. Usually, you don't get an instantaneous and complete combustion reaction; but if conditions are right, and the stoichiometry is balanced, the amount and rate of energetic release is qualitatively different: this is the difference between a fire and an explosion.  If all the stored energy is released suddenly and quickly, a very tiny quantity of fuel is enough to send things flying.  Have a look at the quantities of TNT used in terrible weapons like hand-grenades: often, these weapons need less than an ounce of explosive.
 * In my younger days, I used to volunteer for an educational Chemistry Magic trick show for little kids. We would blow up hydrogen balloons, and hydrogen-oxygen mixture balloons, and set them off to show the grade-schoolers why they should pay attention in science class.  The pure hydrogen balloons made for a neat firework - sort of like burning flash paper.  When we mixed Hydrogen and Oxygen, using the exact same quantity of fuel in the presence of stoichiometrically-balanced oxidizer, the pressure front could blow out the window glass from well-constructed rooms.  So, one party-balloon's worth of H2 is capable of releasing enough thermal energy to cause serious permanent damage, if the combustion goes right.  Moral of this story: don't underestimate fuel energy content; don't mess with strong oxidizers.  And, unless you have a real need to use it, stay away from hydrogen, too - it presents unique hazards.  It's not easy to develop intuition about the size of a reactant - particularly, a gaseous one - and the size of the boom it's going to make: so err on the side of caution, and always assume it can make a really big boom.  Nimur (talk) 23:07, 8 January 2016 (UTC)
 * "Metal in contact with salt water" is not sufficient to make a galvanic cell. You need two different conductive substances in contact with the salt water and in contact (or at least electrically connected) with each other: it's the difference in electronegativity that drives the cell.  The corrosion at one end of the wire certainly fits with the explanation that this is what was going on, but what was the other conductive substance involved?  The cited references don't address that. --76.69.45.64 (talk) 20:47, 8 January 2016 (UTC)
 * From Corrosion, §Galvanic Corrosion:
 * "Galvanic corrosion occurs when two different metals have physical or electrical contact with each other and are immersed in a common electrolyte, or when the same metal is exposed to electrolyte with different concentrations." (Emphasis added).
 * The effect occurs in any condition, as long as there is a potential energy gradient - even if there's only copper; the most common textbook example is a bimetallic junction, or a set of copper and zinc plates separated and immersed in an electrolyte; but there are lots of permutations on the theme. It's also possible that the copper wire might have been in electrical contact with some other metal, or some minerals or impurities in the sand, ....  Nimur (talk) 23:07, 8 January 2016 (UTC)
 * Okay, that makes sense about varying concentrations, but I don't see how it could apply when we're talking about seawater. The sea is pretty well mixed.  Other metal seems a more likely possibility but if that was it then I would have expected it to be mentioned. --76.69.45.64 (talk) 07:37, 9 January 2016 (UTC)


 * Hmmmm, this raises questions in my mind concerning ground potential. If you have a very long, very highly conductive cable buried in the ground, if the ground is not as conductive, can passing storms or tides or other ocean phenomena create charge analogous to a thunderstorm, relative to areas far further inland? Wnt (talk) 16:08, 8 January 2016 (UTC)
 * I'm not sure I completely follow your question, Wnt: in this context, electric charge is not created or destroyed - just moved around. But, you are correct that long electric transmission lines may hold potentials between different locations (superimposed on top of the man-made electric potential that is applied by the various power stations and power distribution terminals).  One cause for those unwanted electric potentials can be geomagnetic or atmospheric static electric potential.  This manifests as unwanted surge-current, unexpected line impedance, and basically just excess wasted electrical energy in the power distribution system caused by natural phenomena.  Reciprocally, power lines can affect those natural phenomena, too - they can interact with geomagnetic and atmospheric electric potentials.  When we are moving around gigawatts of power - which our electric power grid does every minute of every day - those effects are actually measurable.  Nimur (talk) 16:43, 8 January 2016 (UTC)
 * Sorry, by "create charge" I meant "create a concentration of charge in a certain area". What I mean is that if enough of a voltage difference comes to exist between the two ends of the cable, it should create a potential (pardon the pun) for hydrolysis and hydrogen formation to occur, which would not be the case if, say, someone dug up the cable and cut it in a few spots.  So I'm wondering how "live" a dead cable can become, based on weather, and whether that weather includes only the familiar thunderstorms, or if winds and currents in the ocean can create a whole different basis for voltage differences versus areas far inland. Wnt (talk) 19:32, 8 January 2016 (UTC)
 * Suffice to say that such phenomena are rare. Most of the time, corrosion does not evoke hydrogen gas in sufficient quantity to create a hazard.  Nimur (talk) 23:07, 8 January 2016 (UTC)

slower/bigger molecule = bigger cross-section / more reactive? (second-order / SN2)
I'm sorry for starting another question again, but this issue surprises me. In chemistry classes I get taught that SN2 / second-order reaction rates mainly influenced by cross-section (included in the kinetic constant) and collision rate (affected by concentration and order of reaction). This GC/MS study has eluent data that indicates larger primary amines react more quickly or more efficiently with dichloromethane than smaller n-alkyl amines. (Figure 1, page 2.) For each pair of peaks, case the imine ("product") elutes after the amine ("analyte"). This surprises me. For example, (integrating by eye) octylamine : octylmethylimine ratio is approximately around 2-3:1, but when n-decanamine (10 carbons) is analyzed, the situation is reversed: imine product now outnumbers the amine analyte ~3:1. For C12, the imine peak looks bigger as well, predominates over the amine peak for C14, and for C16 and C18, according to the researchers, "nearly all the analyte [amine]" is consumed.

Why would amines with bigger alkyl chains react more completely with dichloromethane? Is it an issue of solubility or polarity? Does a bigger chain in an aprotic (borderline) polar solvent (DCM's dielectric constant = 9.1, compared to DMSO's 47.2) increase nucleophilicity ? Or is it a matter of collision kinetics where a bigger molecule actually increases the reaction rate or probability of favorable collision? Yanping Nora Soong (talk) 23:36, 8 January 2016 (UTC)
 * Strangely this same question was asked here: https://www.reddit.com/r/chemistry/comments/403t1c/larger_straight_chain_primary_amines_eg_c16_c18/
 * Note that the methylene chloride is in vast excess compared to the amine in this experiment. So the rate of reaction would be proportional to the conentration of the amine. Also the amine will have been sitting in the solvent for plenty of time, so that the rate of reaction will have almost no effect, compared to the equilibrium achieved. So perhaps methylimines of shorter alkyl chains are less stable than of the longer chains. Graeme Bartlett (talk) 12:01, 9 January 2016 (UTC)
 * Perhaps the long chain amines form micelle s in the solvent. But I don't see what effect that would have, as the active part is on contact with the solvent. The longer chain compounds also had a lower molar concentration in the experiment as the mass concentration was kept constant, which would favour more of the end product. Graeme Bartlett (talk) 20:16, 9 January 2016 (UTC)
 * I thought of that too. I note that all the chains (C8 to C18) are present in the DCM at the same time. So for example, the C18 chains can still receive hydrogen bonding from the C8 chains. But the longer-chains still reacted more completely. Yanping Nora Soong (talk) 23:41, 10 January 2016 (UTC)