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exchemist

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Everything posted by exchemist

  1. Main engine will be RFO for sure. It’s a big one: 9 cylinders of 90cm bore. (The C will I think stand for container ship, normally meaning higher rpm and shorter stroke than, say, the variant for tankers.) However I have just remembered it used to be the practice in some areas to switch to MDF in coastal movements, to comply with local emissions regulations. So what you posted about MDF could be relevant.
  2. Your link is about MDF. I wonder if the ship was burning that or RFO. (My comments about centrifugal separators relate to RFO.) I heard an interview with a bridge designers saying that if and when they rebuild it, it will probably be a cable stay bridge with piers set much wider apart, well out of the navigable channel.
  3. What puzzles me is the loss of all power. There will have been a low speed main engine and a number of medium speed auxiliary generators. While they may all have used the same heavy fuel oil, it seems odd that all would have failed simultaneously due to fuel contamination, especially given there will have been several centrifugal separators on the fuel lines to the engines. Low speed engines are generally more tolerant to poor fuel than medium speed ones. Maybe loss of electrical power meant they could not control the main engine or the rudder. No doubt the facts will emerge fairly quickly though.
  4. As always, context is critical to the understanding of quotations. Lavoisier was talking of matter not being created or destroyed, in the course of chemical change. You seem to be trying to apply this saying inappropriately, to heat, which is not matter, but a form of energy. Energy is a property of physical systems that is also conserved, i.e. neither created nor destroyed, though this principle was unknown in Lavoisier's time. However energy can and does change from one form to another in the course of physical processes. In the case of the growth of trees, there is chemical potential energy (which is not heat) stored in the molecules that make them up. That chemical energy does not come from heat but from the energy of sunlight, which is captured by the tree in photosynthesis. The Earth is not a closed system, where energy is concerned. It receives energy from sunlight all the time and radiates heat off into space. These two should be in balance. Climate change results when the rate of radiation into space is reduced a bit, due to the atmosphere slowing down the rate of escape of heat. It is caused by the absorption of infra red radiation (heat radiation) by gases and vapours such as water, carbon dioxide and methane.
  5. Yes I think one of my son's friends at school, who was autistic, went on do an arts subject at university. And we have the example of Greta Thunberg of course.
  6. OK, well in that case what I posted shows it cannot be a widespread effect, at least. But I suppose it does not rule it out as an effect in certain individuals.
  7. I may have misunderstood then. What exactly is the hypothesis that has not been refuted?
  8. I would not have guessed, Markus. Except that you are rather good with hard mathematical physics…..🙂
  9. Yet clearly it has little long term effect in practice, since amoxicillin is widely prescribed (in the US, as much as 24% of all antibiotic prescriptions:https://www.definitivehc.com/resources/healthcare-insights/most-prescribed-antibiotics) and we do not see any mass outbreak of sterility in the population.
  10. Thanks. I looked at that but it was not clear to me it can work with Apple Mac OS and Safari.
  11. My son knows several people, formerly at school and now at university, who are on the autistic spectrum and obviously highly capable. The fact - which I had absolutely no idea about - that @Markus Hanke is also on the spectrum (!) is another illustration. I have my suspicions that various eminent figures in history (Newton, perhaps?) may also have been. People of my son's generation are getting quite comfortable with the idea that autistic people can fit into society perfectly well. But then there are other cases that are clearly very difficult. At the other end of the scale, when my son was small one of his schoolfriends was a little girl who had an autistic brother, who still could not speak at the age of 5. (This girl once told him that when she grew up and married him (!) she wanted 3 children: one boy, one girl and one autistic. )
  12. I have now experimented with AdBlock Plus, which is free on the App Store, for my iPad. At first it did not do much, but a few days ago I found the app contains an option to permit what it calls non-intrusive ads, which is by default enabled on the grounds that the AdBlock people recognise websites need to make some money. My experience however is that that still permits most of the annoying, moving ads that are so distracting to the reader, e.g. on newspaper websites, to get through. I have now found that by turning that off I can suppress these and my reading experience is now vastly improved. I have the feeling it may also stop the ads coming up in the middle of YouTube videos, though it still allows the ones at the start. I'll give it a few more weeks and if no snags emerge I'll install it on the laptop as well.
  13. This seems written from the point of view of the company (Honeywell), that was and maybe still is trying to promote this apparently expensive and and hard to install system. As I read it, it would only work at 35 airports and would need to be customised for each one. So hardly surprising the authorities did not jump at the chance. If you read on in the piece, there seem to be less costly alternatives in development.
  14. I got off my hamster wheel some time ago. I don't understand the rest of your post at all.
  15. It does seem to be a contentious area: https://en.wikipedia.org/wiki/Male_infertility_crisis Seems doctors don't believe there has been a significant fall in fertility while a number of meta-analysis studies suggest there is at least a fall in sperm count . It may be important that that does not necessarily lead to reduced fertility, provided the count remains above a certain threshold, which apparently it generally does. Curiously, I can find no mention anywhere of antibiotic use having been considered as a possible factor.
  16. As far as I know cellulose, e.g. cotton, is hydrolysed by acid, so by H+ rather than H2O per se. Wool is keratin, which is a fibrous protein. The amide links in this can also be hydrolysed under acid conditions. I don't know whether in neutral water either of the these processes occurs at a perceptible rate, but I suppose it is conceivable over very long periods of time. Maybe someone else here knows more about it.
  17. If they are miscible, i.e. you don't get a layer of one of them on the surface that prevents the materials beneath evaporating, then to a first approximation they will each evaporate at a rate given by Raoult's Law. This states that the vapour pressure of each component will be proportional to its mole fraction in the mixture. For example if a component comprises 1/3 of the molecules in the mixture, it will contribute a vapour pressure 1/3 that of the pure substance. There can be deviations from Raoult's Law when the molecules of 2 substances have more affinity for one another than for molecules of their own sort, or conversely when they have stronger affinity for their own sort than for the other. Here is a link to a fuller explanation: https://en.wikipedia.org/wiki/Raoult's_law. The 2 graphs give you first what happens in an ideal case and then what deviations from Raoult's Law can do. But in all cases the principle will be that of contributing a vapour pressure (which translates to an evaporation rate) more or less in proportion to how much of the mixture each components represents. N.B. this is on a molar basis (not mass or volume), as it depends of how many of the molecules in the evaporating surface layer are of each substance. So if you add a miscible slow-evaporating ingredient it will only slow down the evaporation of the other substances according to proportion of them it replaces in the mixture. (The limiting case is adding salt to water. The vapour pressure of salt is negligible. Dissolving salt reduces the vapour pressure of water and thereby elevates the boiling point. But it can only do so to a limited extent because you can't dissolve that much salt in water, so the maximum mole fraction has a limit.) If however it is a immiscible liquid of lower density, it will float as a layer on the surface and prevent what is beneath from evaporating.
  18. Identical rubbish previously posted elsewhere and shut down, so now it pops up here.
  19. There have, I believe, been reports of reduced sperm count in industrialised societies and some discussion about what might be responsible. Things like endocrine disruptors get mentioned but so far as I know nobody has fingered the widespread prescribing of antibiotics.
  20. I had an idea it might be something like that. So then the issue would be whether a commercial scale mineral transport operation could function with such long intervals.
  21. OK, Interesting. Roughly how many of the requisite planetary alignments would there be per year, or per decade?
  22. But you still stigmatise them as ill. So ill but stable?
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