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exchemist

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Everything posted by exchemist

  1. Since there are 10⁶ ml in one litre of water, there are 10⁵ml in one dL. Equating 1mg with 1ml is only valid for substances with a density of 1g/ml (or 1000kg/m³ in SI units). So-called "cholesterol" in blood is not in fact the chemical substance cholesterol, but particles made up of a range of substances including fatty acids, esterified and unesterified cholesterol, proteins etc. From what I can find on the web, these particles have densities ranging from approx 1.05-1.2g/ml. (Blood plasma has a density of 1.006g/ml , apparently.) The chart I found is this one: https://www.nature.com/articles/s41598-021-95451-3/figures/1 Whether these differences in density are significant or not in the context of your enquiry I do not know.
  2. I would imagine one difficulty relating the present warming to previous interglacials is the rate of CO2 increase and consequent warming has no parallel in the past. We will be farther from equilibrium as regards melting of ice, isostatic rebound etc. than past warming processes. So any effects that take time to manifest themselves can be expected to lag the warming that causes them.
  3. Since the pipes and connection will all be behind the appliance, I should have thought there would be little need to worry about the appearance of the piping.
  4. Sounds more like Japan. Presumably an operational hazard in the US. 😁
  5. I'm in the UK but surely all you need is a couple of U-brackets, like this, isn't it? :-
  6. I recall similar claims cropping up a number of times. I've always tended to dismiss them as psychological manifestations rather than physical effects, though no doubt they can be real for the sufferer, whatever the cause.
  7. There was a thread on this back in 2005: A helium (or hydrogen) balloon can lift of the order of 1g per litre of balloon volume.
  8. Not an alkali metal, as all of these react pretty violently with oxygen in the air.
  9. 0% is interesting. There may I suppose be special "stove glass" with an expansion coefficient even lower than Pyrex. Anyway yes, thermal expansion of a part in the middle of a plate, that is hotter than the periphery, will tend to make it bow up or down, or twist, to relieve the strain - i.e. warp. One other thing: glass is a good thermal insulator. So the glass top may also protect whatever is underneath from getting too hot. Anyway, glad you found the comments helpful and good luck with the repair.
  10. Well I suppose you could get the MSDS for a start. There will generally be information about eye irritation and inhalation on those. But you may have already done that.
  11. The relationship would still exist, I think, since both energy and mass are properties of matter that do not depend on light. By the way the equation does not relate energy with matter: it relates energy with mass. That distinction is important.
  12. You don't have Siri or equivalent, permanently active, in your TV though, do you? Obviously if you have Siri active, you have chosen to have it listen to your voice for commands. What this is about is having an IT system listen to (and send data on) your voice without your consent.
  13. Do you know that ? I should have though that could be grounds for a lawsuit for invasion of privacy. Can I read about this somewhere? (As it happens, I don't have a TV, but I think it would be scandalous if true.)
  14. It's a new feature on a number of forums I subscribe to. It started about a year ago, I think. When you attempt to navigate between threads, or return to the home screen, you sometimes - not always - get instead a full page ad, which you have to cancel before you can see the screen you want. For what it's worth I'm on Apple with Safari as my browser. What makes it newly tiresome for me is this aggressively advertised Chinese outfit TEMU, presenting you with a totally random range of crap, sometimes including completely unidentifiable objects. I've no idea who these people are - a sort of Asiatic Amazon perhaps? - but they are of zero interest.
  15. Actually that suspicion about phone mics is something I have also heard from other people. Either it's just a meme or there is something in it. Perhaps we should look the topic up on the web, oh wait ..........
  16. I'm no expert in this area but I'll have a go, to start off the discussion. I presume the warping you refer to is due to thermal expansion of the metal, in those areas where it gets hot, whereas the rest of it stays cool. There is a table of coefficients of thermal expansion here: https://www.engineeringtoolbox.com/thermal-expansion-metals-d_859.html According to this, the coefficient for stainless steel almost double that of mild steel, so it would be expected to expand more with heat and warp more. This is just for metals but here is one that includes glass: https://www.engineeringtoolbox.com/linear-expansion-coefficients-d_95.html According to this, plate glass is similar to stainless steel while unqualified "glass" is similar to mild steel. Given that glass is brittle, it will crack if it experiences too wide a temperature variation across the specimen. That being so I am wondering what the design of this cooker is and whether you may have inadvertently removed something that avoids a large temperature differential from being created, or else you have not included a gap, or cut, or flexible fixing, somewhere, that permits differential thermal expansion. Alternatively it may be a question of thickness. Frying pans are commonly made of steel and cheap ones can bow upward in the centre if they are too thin. However better quality ones (heavier, thicker ones) seem not to, presumably because they can contain the thermal stresses within the metal without bending appreciably. Regarding glass if, it was not just glass but Pyrex, this has a lower coefficient of expansion (~3 x 10⁻⁶mm/mm/ Cdeg) than any of the above materials and can be made thicker and a lot more thermally resistant. P.S. cross-posted just now with @swansont
  17. I don't think whatever algorithm selects the ads to display considers the forum they are displayed on. It's probably much more to do with what it thinks based on whatever it has gleaned about your browsing and on-line purchase history. Since I do what I can to minimise this , e.g. via blocking trackers, I get weird ad selections: funeral services, drilling machinery, women's fashion and ads in Chinese characters. (When I looked up a few words in Dutch for another forum, I started getting Dutch websites popping up on my search engine too - it's all rather creepy.) All a bit baffling and annoying, but I tell myself the alternative would be that we would have to pay a subscription for a forum like this, so it doesn't do to grumble too much.
  18. This looks like another example of “enshittification” : https://en.wikipedia.org/wiki/Enshittification Cory Doctorow gave an excellent lecture on this in January. Here is a link to the transcript. It’s very well written, rather in the style of Michael Lewis’s Liar’s Poker: https://doctorow.medium.com/my-mcluhan-lecture-on-enshittification-ea343342b9bc Long, but very readable - and worth the read. He muses that we may be entering the enshittocene era.
  19. That's how I interpret the diagram. Though one has to keep in mind this is binding energy per nucleon. What intrigues me, not being a nuclear physicist, is the spike at helium, and the smaller one at oxygen. These elements seem to have stability that lies off the curve. Are they filled nuclear shells or something?
  20. But what's the point? All you do is make deuterium, which we can easily extract from seawater anyway, from alpha particles, by a process with <0.01% efficiency that consumes a lot of energy however it is supplied. What have you achieved? A net fission of helium into deuterium. What use is that?
  21. As the little "m" s appear once on each side of your equation you can cancel them, but that leaves the big M. So the "a" in F=ma should be set equal to GM/r². There has to be an M in it because the acceleration due to gravity depends on whether you are standing on, say, the Earth, or the Moon which has less mass and therefore weaker gravity. Newton's expression is completely general and can be used for any body, dialling up and down M according to the mass of the body in question.
  22. Irrelevant. All you need to know is the binding energy per nucleon of the reactant species at the start and of the product species at the end and do the arithmetic. The route by which you carry out the change has no effect on the overall energy change between the two. What you are proposing is the reverse of the fusion people are trying to achieve with Tokamaks etc. You are turning a helium nucleus into 2 deuterium nuclei rather than the fusion process of turning 2 deuterium nuclei (or one deuterium and one tritium) into helium. Since that process releases energy, which is why people are trying to do it, your proposed process must necessarily absorb the same amount of energy. The binding energies per nucleon are shown on this graph, which shows the enormous gap between ²H and ⁴He:
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