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Posts posted by exchemist

  1. 9 hours ago, swansont said:

    The electron that’s captured is an “inner” electron (1S) and bonding is via “outer” electron(s), so the effect on the decay is likely minimal. That Be sees an effect makes sense to me, since it only has the four electrons, so you would have the most possible effect on the 1S orbital depending on what bonds are formed.

    I was going to make the same point. I suppose it is true that the 2s also has non-zero electron density at the nucleus, so capture could in principle take place from the 2s as well as from the 1s, though with lower probability since the 2s electrons spend more time further out. 

    24 minutes ago, Ken Fabian said:

    But the chemical compounds they are part of are affected when the atom undergoes radioactive decay. Not just the radiation from that decay damages biochemistry, the change from one element to another does too, both by breaking up the compound they were part of and from the chemical effects of the resultant compounds. I think the harms from radioactive materials are more biochemical in nature than direct radiation damage.


  2. 6 hours ago, geordief said:

    Maybe it was someone else (or my memory has wind blowing through the attic)

    No matter.

    Is there a "father" of the maths in QM?

    (like Minkowski for GR I think)

    Heisenberg? I think it was he that established the operator:observable formalism and the use of matrices. But the development of QM was very much a collective effort: more so than relativity.

  3. 1 hour ago, paulsutton said:

    Back in the days of Windows 3.1, I had some software called periodic table of the elements,  this had a nice feature that would display a picture of an elements decay tree.

    I am looking for something similar,  however I am not sure if there is anything, but  not sure if decay tree is the correct term I should be using.

    If i can determine better search terms,  I may have more success,  any suggestions please?.   While I am running Debian Linux here, if there are suggestions for Windows and or mac, than those will be helpful to other users.  I have gperiodic for Debian but that doesn't seem to have this information.





    I must admit I haven't seen anything like this organised for a complete periodic table. I should have thought it would be quite difficult, as each individual radioisotope has a different decay mode, so you might need several different chains for each element if there is more than one radioisotope. 

  4. 12 minutes ago, Sensei said:

    Sometimes this is the case. If the exclusive mode of decay is electron capture, then a fully ionized atom cannot decay because there are no electrons in the shell(s).

    Beryllium-7 is an example of an isotope that has a slightly different half-life when metallic than in compounds.



    Interesting. But surely the only example of a chemically produced ion with no electrons is H+, isn't it (even that is doubtful)?  And the proton is stable.

    Your beryllium example does not reflect that, obviously. The change they measured in electron capture rate was 1%   - and this process is highly exceptional, which is why it was newsworthy. 

    For people like Paul, it seems to me the best answer remains that radioactivity is independent of the chemical environment of the atom. That is 99% true at least.


  5. 6 minutes ago, paulsutton said:

    So from this we can perhaps conclude there are both friendly and unfriendly mutations.  We have seen mutations at work with the variants of the Covid 19 virus.  So the virus adapts,  also with things like anti biotic resistant bacteria.   In terms of friendly, yes evolution, unfriendly Cancers etc.

    Sure. It's the job of Darwin's famous "natural selection" to weed out the useful mutations and ignore or discard those that are useless or actively harmful. (Nowadays we know the mechanisms are more complex than just that, but the basic principle remains valid.)

  6. 3 minutes ago, paulsutton said:

    Thanks, this makes sense so I would guess that Carbon 13 is also perhaps made with cosmic radiation too, 


    So one example could be perhaps that Bananas contain radioactive isotopes of Potassium.

    Yes in general there will be a small proportion of radioisotopes in everything. Life on Earth has evolved around this fact. Our cells have systems that repair DNA damage, to stop this wrecking the stability of cell replication. Nevertheless, DNA damage from radioactivity may be one of the driving forces behind evolution! You need mutations to come from somewhere, after all.    

  7. 1 hour ago, paulsutton said:

    I am trying to find out if compounds of Radioactive atoms such as Uranium are still radioactive.  From a search I found


    Which has lots of information, including information on the various Compounds of Uranium, but I can't see anything relating to radioactivity.

    Just curious, I would suspect they may be in some cases.  


    Yes indeed they always are. Radioactivity is a function of the stability of atomic nuclei. These are not affected at all by the way atoms may be combined in chemical compounds. Chemical bonding is entirely due to the electrons in the atom, which lie far outside the nucleus.

    In fact, to give you an example, the basis of carbon 14 dating relies on this. Carbon 14 is formed in the atmosphere due to its constant bombardment by cosmic rays. The result is that a certain proportion of atmospheric carbon dioxide molecules will have a C14 atom in place of the usual C12 one. When a plant absorbs this in photosynthesis, the carbon 14 is incorporated into a sugar molecule, generally used to build the cellulose skeleton of the plant. So a living plant always has the same ratio of C14 to C12 as the atmosphere does. However, when this is a tree that is cut down and used to build, say, a boat, if we dig the boat up 5000 years later we can tell when the tree was cut down by the amount of C14 that is left, the rest having decayed away, because C14 stopped being incorporated at that point and, being radioactive, it declines from that point on, so the ratio of C14 to C12 changes.    

  8. 10 hours ago, we2 said:

    We don't see any intro threads so I guess we will just jump in and see how it goes. 

    We are a married couple for 25 years and also very active in the nudist community. 

    we have also been born again Christians for 25 years as well. 

    We have always been amazed that fellow Christians (and the general public) condemns public nudity when the Bible never once condemns it or names it as a sin. 

    we would love to get into a respectful discussion with anyone out there that agrees or disagrees. 

    We will promise to reply to everyone who posts. 

    BTW, all nudists are not swingers and very few swingers are nudists so that is NOT what we are on here for 


    Adam and Eve set the original precedent, I suppose.

    I can't see it's a big deal in Christianity. To be honest, the issue in practice is not disturbing other people or drawing attention to oneself. That's very much a matter of where you are and what the expectations are in that situation. For instance it is quite normal to wear very little on the beach, but if one were to dress like that on the London Underground*, it would be a big distraction.  So if you are nudists, in a place set aside for that, the person who would draw attention to himself would the one dressed in a double-breasted suit.  


    * However when my late wife worked in Rio de Janeiro, it was perfectly normal to see a guy in speedos on the bus, with a surfboard under his arm, next to all the people dressed for the office.  

  9. On 9/21/2022 at 6:17 PM, Externet said:


    From memory, the belly red; the wingtip white strobe and the top red of fuselage beacons flashed sequentially; not simultaneous.  The questioned wingtop row of dots may be coincidental with one of them flashing.  The dots appeared like tiny 10mm diametre / 3mm high bumps when seen with the ambient light after aircraft stopped, but their diffused light was like 5cm diametre as seen on image.  There is a possibility of being reflective adhesive :confused: tape dots.  My vision is not superb, but was not a dream. 

    Here is the best reply I got on the other forum:

    "They are vortex generators. They generate tiny vortexes very close to the wing surfaces, thereby disrupting the laminar flow near the wing.

    One of their most important functions is to make the stall break more gradual. If one wing of the aircraft stalls suddenly while the other wing is generating lift, the aircraft will roll violently towards the stalled wing. Using ailerons to try to counter this will just make it worse since ailerons increase the (effective) angle of attack of the wings when deflected downward, and thereby deepen the stall.

    They also slightly reduce stall speed by ensuring laminar flow is NOT maintained. This is somewhat counterintuitive since laminar flow is a very efficient regime for an airfoil to work in. But in a laminar flow airfoil, again the stall break happens very suddenly. The turbulence created by the vortex generators ensures that any stall occurs gradually by disrupting the (primarily) laminar flow over the wing, and allows the wing to keep flying while partially stalled.

    They also increase drag and reduce cruise speed at a given power setting. They are still seen as worth the tradeoff because they increase maximum takeoff weight by providing more margin against violent stalls at low airspeed, and the slowest airspeed that an airplane can get off the ground is one of the primary determinants in both runway length needed and maximum safe takeoff weight for a given runway."


    So my guess is they may look like lights at night, due to being illuminated by the rotating beam of a fuselage navigation beacon, but in fact they are vortex generators.

  10. 51 minutes ago, random_soldier1337 said:


    FYI, thought I should clarify (probably should have mentioned in OP), I am making a CFD simulation in ANSYS Fluent and the containment which forms the domain of interest should be receiving the well mixed gas mixture. I have to figure out the pipe length leading to it so that I do not add unnecessary spatial meshing.

    I suppose you might get some help from Fick's Second Law of Diffusion for gases: https://en.wikipedia.org/wiki/Fick's_laws_of_diffusion

    But I can't help thinking it is a bit artificial to assume two parallel, laminar flows down the pipe, which mix solely by diffusion from each into the other. I's have thought that introducing some turbulence would shorten the length of pipe needed considerably.

  11. 41 minutes ago, KlingGeofrey said:

    My son’s 3rd grade math is always asking him questions about measurements and equivalents. He always comes and asks me for help when there are questions like: How many quarts in a gallon? (A gallon is equal to 4 quarts) How many cups are in a gallon? (There are 16 cups in a gallon)  How many cups in a pint? (There are 2 cups in a pint) How many cups are in a quart? (4) When I taught foods classes at a high school, these measurements always seem to be a challenge, too! Someone have a fun and easy way to help teach these measurements?

    No. Move to Europe, where these silly antiquated measures are not used.😁 

    More seriously, I went to school in the UK during the transition to metric units and had to learn both at school. If you live in a benighted country with these ancient systems, you just have to learn them, I'm afraid.

    P.S. I never knew a "cup" was an actual measure. We had to learn gills, quarts and gallons. It seems there are 2 gills in a cup. So I've learnt something today.  

  12. 35 minutes ago, StringJunky said:

    I have to say that putting politically-charged subjects into class lessons that don't require them does annoy me. When one starts sliding such materials into coursework, it smacks of indoctrination. 

    Yes I agree. However it is normal in most western countries for illustrations in children's books to show a mixture of sexes and ethnicities, simply to make sure all the children see the book, and the subject, as being "for them". Especially perhaps with maths, as this has some baggage of -ve stereotyping, viz. a history of being seen as "nerdy", or "for boys" and so forth.  So if that's all it is, then it's disgraceful that books are withdrawn for it.  

  13. 2 hours ago, NTuft said:

    to paraphrase @swansont, "time is the integral of frequency".

     f, units Hz, or s(econds)-1, ergo, period T in units s1

    I think vibration is more fundamental than distance. What about distance as in wavelength?

    I don't think I agree that time needs a motion -- it sounds like you're referencing speed. I think I agree with @md65536 that we can simply, arbitrarlly, define a period, and then we have a time period... though in some fashion this may entail an abstract clock.

    Now, as for space, @Mitcher, do you suppose we can look at geometry à la mode de group theory, as non-circular defined? Could it not be said it is self-sufficient, that it is defined through mathematics, or do you suppose there is recursion there to circular definition?

    The integral, with respect to t,  of 1/t is: ln t +C, surely?  

  14. No reply yet from the person I was hoping might respond, but someone else reckons they are vortex generators to improve the air flow towards the wing tip, where, due to the flexing of the wing, it is (so I'm being told) the part likely to stall first as the angle of attack increases. 

  15. 1 hour ago, paulsutton said:

    Good point, i did comment on twitter that I hope fracking is a short term thing until we get alternatives up and running.   But yes we should put solar panels on a lot of buildings from the start,   and attach to older buildings too,   the new solar tech that has been developed not only seems to make panels more efficient but also more recyclable at end of life. .

    Our government are here for short term action,   if we need engineers etc then we need to push engineering from year 7 (first  year of secondary at age 11)  so that we can develop the interest and also the skills for the future,  instead we keep kids at school till 18.

    For many school isn't working, so why not let them leave at 14,  and work in engineering (in this case) as apprentices. By the time they are 18,  they will have skills, experience and qualifications that make them useful immediately,  compared to their peers who stay at school.

    There are plenty of routes back in to academia later on n life too, 

    Yes. The problem is fracking may be sold by our idiotic government as short term, but it isn't at all. The best short term options are renewables.

    Regarding education, that's a different topic but I've just listened to an episode on "The Briefing Room" on Radio 4 about Britain's poor economic productivity, which (among other things) laments our rigid education system. This fails to turn out the sort of mid-skilled people one needs to provide the bulk of the workforce in a higher productivity economy, like that of Germany or France. Our record is very poor compared to theirs. We are fixated on A levels, which are extraordinarily narrow (my son chose the IB instead), and on going to university to study more narrow disciplines, often of questionable value. Different governments try different gimmicks, like the apprenticeship scheme, but there is no consistency and so it never takes root and starts to show results.   

  16. 6 minutes ago, paulsutton said:

    So what about existing fields that have been closed down?, is the time taken to get them back up any shorter ?  I know some have apparently concreted over.

    >5 years is a long time, 

    I guess the government wants to be 'seen' doing something, only from this,  it seems like a sticking plaster over a gunshot wound.

    If they want more energy, cheaply and fast, they ought to be erecting wind turbines and encouraging farmers to put solar panels in the fields instead of trying to ban the practice. That could make a difference within 18 months, if they can bypass the planning process for an energy emergency. But they are far right fuckwits, unfortunately. (Rees-Mogg as Energy Minister? Seriously?) 

    My understanding is that some abandoned N Sea fields - which would be economic once more at today's stratospheric prices - could be restarted a lot faster than 5 years, but I don't have chapter and verse, I'm afraid.   

  17. 1 hour ago, paulsutton said:

    The UK prime minister, Liz Truss has announced an end to the ban on Fracking in the UK.   I would be very interested in being able to separate fact from fiction on this topic.

    I understand the basic principle which is to pump water in to underground reserves of natural gas in order to force these to the surface.    The explosives are needed to open up the rocks that hold the reserves of gas.

    I goes without saying the usual social media channels will be full of all sorts of 'opinions' as to this causing earthquakes (which as far as I understand will be very low in magnitude anyway) and a host of other theories to help their objection argument.

    Hence any links to actual papers or research and factual information would be helpful,  as I am hopefully going to be in schools as a Teaching assistant then being able to present some real facts would be great.   But this will be useful anyway.



    I don't think explosives are used, are they? My understanding is it is done via hydraulic pressure.  

    An article in yesterday's Guardian, from a former geologist for Cuadrilla,  expressed the view that rocks in the UK are too heavily faulted for there to be many contiguous reserves, big enough to be economically recoverable. The current boss of Cuadrilla, interviewed today on R4, seemed more sanguine. However his estimate of recoverable reserves seemed to be 10x that of the British Geological Survey. I can't find numbers on this, unfortunately. But it seems there is no consensus on the size of the prize.

    What I have found is papers on the BGS report on induced seismicity: https://www.gov.uk/government/publications/review-of-the-geological-science-of-shale-gas-fracturing

    The other things to bear in mind, apart from induced seismicity, are the long lead time before gas from these new sources can enter the market (>5 years, typically) and the fact that when they do so, they will be priced at the global market price, so they will not make supplies any cheaper, though they can add to security of supply.  



  18. 2 minutes ago, KoelpinTad said:

    I'm working on weight. I often have to convert ounces to grams or grams to pounds. Here's how I usually do it: write the numbers down on paper, find the formula, and then enter the numbers into the calculator. Everything seems complicated and takes my time, it makes my work slow and inefficient.

    I am looking for a software or a website that allows me to convert easily and quickly.
    Can anyone recommend it to me. Any suggestions are always helpful. Thanks everyone

    I found this immediately on a web search: https://www.metric-conversions.org/weight-conversion.htm

    There must be lots of them.  

  19. 1 minute ago, iNow said:

    The clear issue here is the mistake you've made by calling Coors Light a "beer." It's better referred to as beer adjacent swill water. /BeerNerdShade

    And I thought that was "Budweiser", the one made partly from rice. 

    Real Budweiser, from Budweis,(Budweiser Budvar) is actually not bad, however. For a lager. 

  20. 11 hours ago, random_soldier1337 said:


    In my situation, I am dealing with two ideal gases traveling down a pipe at the same bulk velocities. I am only considering a 1-D treatment at the moment and I would like to find out at which point the two gases should be considered a well mixed, homogeneous mixture. Would anyone know either the particular formulation or even the subject matter to consult to determine the well-mixing of gases?

    Thanks and regards.

    You can also get "static mixers" to put in the pipe, to speed up the mixing and ensure it is complete: https://komax.com/the-gas-static-mixer-produce-high-quality-process-gases-for-many-application/


  21. 4 minutes ago, Externet said:


    From memory, the belly red; the wingtip white strobe and the top red of fuselage beacons flashed sequentially; not simultaneous.  The questioned wingtop row of dots may be coincidental with one of them flashing.  The dots appeared like tiny 10mm diametre / 3mm high bumps when seen with the ambient light after aircraft stopped, but their diffused light was like 5cm diametre as seen on image.  There is a possibility of being reflective adhesive :confused: tape dots.  My vision is not superb, but was not a dream. 

    I'm sure you are not dreaming! Since the beacon is often a rotating light, like a lighthouse beam, I imagine it would be expected to illuminate each one in sequence, though very rapidly. But we probably need comment from a pilot. 

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