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exchemist last won the day on July 16

exchemist had the most liked content!


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    Rowing, choral singing, walking.
  • College Major/Degree
    Chemistry MA, Oxford
  • Favorite Area of Science
  • Biography
    Trained as a patent agent, then gave it up and worked for Shell, in the lubricants business for 33 years. Widowed, with one teenage son.
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Organism (8/13)



  1. I think the troll has now been banned, but the mods haven't yet dreamt up a suitably humorous post to record it for posterity. But what a twat, eh?
  2. If such allergies affected a significant proportion of the population and involves enough of the foodstuffs consumed then it would generate evolutionary pressure, I'm sure. But as it affects only a small fringe of people, I suppose it's possible that the rate at which allergies arise is in balance with the rate of extinction of them. There are examples of food intolerance modifying a population, for instance the ability of adult N Europeans to consume animal milk without trouble, whereas lactose intolerance in adults is the default in many populations originating outside N Europe.
  3. Yes of course they do - though people argue about how to interpret QM. By the way, "common sense" is a lousy guide to either QM or GR. Both were developed by rigorously following the observations, without preconceptions.
  4. Yes, yes, but we're all waiting for you to start spamming. Then we'll ban you. 😆
  5. Mechanical energy can be converted into non-mechanical forms of energy, e.g. chemical or electrical energy. So it is obvious that mechanical energy is not conserved.
  6. Yes, it's curious. It rather looks to me as if he wants to get banned, perhaps (I speculate) in order to reinforce a worldview of victimisation by woke atheists, or some such Trumpy paranoia. At least, that's what comes across. Either that or he's just a random loony with "issues". Anyway, I expect he'll get his wish eventually.
  7. Yes exactly. The spectrum of any element or compound is usually a series of lines (atoms) or bands (molecules) of absorption or emission at characteristic wavelengths, corresponding to the various natural excitations that are possible in the species in question. With a complex mixture it can be quite tricky disentangling them and assigning them to whatever is responsible. One generally looks first for certain strong lines or bands that are not often overlain by something else, or in the case of water certain features like the broad blob of absorption it gives in the IR. Once you know it is there, you can allow for what it may be doing elsewhere, to obscure other things that may also be present, hidden behind it.
  8. I think you've nailed it. I did not know there was such a thing, but here is one commercial range of them: https://www.olympus-ims.com/en/xrf-xrd/xrf-handheld/
  9. So she went into the garden to cut a cabbage leaf, to make an apple pie; and at the same time a great she-bear coming up the street, pops its head into the shop. 'What! no soap?' So he died, and she very imprudently married the barber; and there were present the Picninnies, and the Joblillies, and the Garyulies, and the grand Panjandrum himself, with the little round button at top; and they all fell to playing the game of catch as catch can, till the gunpowder ran out at the heels of their boots.
  10. The only Travis Trenton I can find is some kind of marketing manager with T-Mobile: https://www.linkedin.com/in/trentontravis?original_referer=https%3A%2F%2Fduckduckgo.com%2F Is that who you mean?
  11. According to this source there are both magnetic and non-magnetic grades of stainless steel and the magnetic grades have poorer corrosion resistance: https://www.eclipsemagnetics.com/resources/are-all-stainless-steels-magnetic/
  12. There could easily be a huge market for it. Hydrogen would be close to a drop-in replacement for methane in domestic heating (you can put up to 25% into the supply today without even changing burners). Also I believe hydrogen is thought to be a good candidate for heavy duty truck transport, for which batteries would be very large and heavy. We already have hydrogen buses in some places. It needs something to kick-start it though - probably government. I don't think, myself, that trying to totally decarbonise shipping is a top priority. Switch to lower carbon liquid fuels in the medium term while you go for other sectors with more impact on total emissions.
  13. IR radiation is of the right order of frequency to set up vibration in molecules which have a dipole (partial charge separation), giving up its energy to the molecule in the process. So this is what makes a molecule absorb in the IR. What you are seeing is absorption due to different modes of vibration of the molecule. CO2 can stretch or it can bend. I rather think the left hand band is the stretch and the right hand one is the bend. So it's not several different species. It's all CO2. In general, the IR spectrum of a given molecule has a number of absorption regions, not just one.
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