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exchemist last won the day on February 29

exchemist had the most liked content!


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    Rowing, choral singing, walking.
  • College Major/Degree
    Chemistry MA, Oxford
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  • 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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Scientist (10/13)



  1. I'm certainly not going to use that Philadelphia stuff. 😝 I'm going to use a hard cheese with some flavour. But that picture looks as if it may be sweet cassava flour (polvilho doce - doce may mean sweet, like dolce.) As I say, I have a recipe. All I need is to source the right kind of cassava flour. The recipe calls for sour not sweet (polvilho azedo). I'm going to ask my cleaner to get me some, from the Brazilian shop close to where she lives in Streatham. If it works, I may post it for comparison. The key thing will be to get that special chewy texture that you can't get with wheat flour. They are nice with a cup of tea, in the afternoon, as an alternative to the cheese scones I sometimes make.
  2. As far as I can tell it seems to be the same stuff, basically. There seem to be two versions of cassava flour, sweet and sour, the latter being fermented before final preparation. I am interested in this as I want to make pan de queijo, which one of my son's Brazilian nannies/babysitters used to make and which I found delicious. I now have a Brazilian cleaner who brings me some occasionally but she doesn't make it herself and it is not quite as good. Cassava flour is not easy to find in London, though there are Brazilian shops where one can get it. I have a recipe that I found on line that calls for sour cassava flour.
  3. Disappearance of the major component of the tides, with a devastating effect on intertidal organisms and probably other ecosystems that benefit from the flushing action of tides.
  4. Me for a start. What did you mean by suggesting he might (rhetorically) have a gun to the back of his head? What a needlessly aggressive and uninformative remark. And then you made a further ridiculous statement about it being naïve to think taxes and tariffs can "solve" problems. Nobody suggests they "solve" anything of course. Alternatively, to deny that taxes and tariffs can play a role, by modifying the behaviour of commercial enterprises, if that is what you meant to say, would be equally absurd. In this case there is a particularly strong case for taxes and tariffs, since one of the great problems in addressing climate change is the lack of any direct market-based feedback between the products (and their pricing) available to consumers and the resulting costs down the road for us all due to climate change. So, all in all, a fairly poor post from you, I thought.
  5. The problem, as @chenbeier says, is that a carbonyl group will react with a Grignard reagent much faster than a carboxylate. So any acetophenone produced would immediately react in preference to the remaining carboxylate. I’m not sure whether a carboxylate anion will react at all with a Grignard reagent. Nucleophilic attack on an anion seems like a bit of an uphill struggle, though it’s true most of the -ve charge will be on the O atoms.
  6. Carboxylate anions are not very strongly electrophilic, if I remember correctly. What do you think will happen? Something has gone wrong with your post.
  7. What I meant is that it is a bit of a stretch to claim the Holy Roman Emperors represent a continuation of the Western Roman Empire. They were not Romans, they ruled over various chunks of continental Western Europe, and did so from places nowhere near Rome, like Aachen.
  8. Defying Hitler. Synopsis: "Sebastian Haffner was a non-Jewish German who emigrated to England in 1938. This memoir (written in 1939 but only published now for the first time) begins in 1914 when the family summer holiday is cut short by the outbreak of war, and ends with Hitler's assumption of power in 1933. It is a portrait of himself and his own generation in Germany, those born between 1900 and 1910, and brilliantly explains through his own experiences and those of his friends how that generation came to be seduced by Hitler and Nazism." I thought now would be a good time to read how a demagogue, encouraging a cult of personality, can subvert the institutions of the state and seduce a population, little by little.
  9. Yes but the Holy Roman Emperor was just an honorary title that developed from the coronation of Charlemagne as emperor by the pope, in return for the protection he provided to Rome against the Lombards etc. Whereas the Roman Empire in the East survived in Constantinople until 1543.
  10. I don't think so. The basic problem, as I understand it, was over-extension of the Empire and consequently increasing reliance of the army on colonised people to man it. I think competition from the Goths, notably Alaric, had something to do with it as well. But that was not until c.4th AD. I think it was still flourishing in the c.1st.
  11. Sounds good in principle but I can't help wondering how the industries affected are going to calculate the numbers to submit on imported goods, and how the EU will be able to check they are genuine.
  12. No. The pairing is dictated by the way the H bonds line up and this makes only 2 specific pairs fit together, namely A-T and G-C. This is what ensures that a single strand of DNA, when it has been unzipped, will attract the same sequence of bases as the complementary strand that was unzipped from it, thus making another copy of the previous complementary strand. So your model should have A-T and G-C links only between the strands.
  13. Sure, it makes perfect sense. One wants maximum resonance from the body of the instrument. I would presume the use of drying oils, such as linseed oil, would help repel the moisture from sweat. Which reminds me of that joke in the Molesworth books about the boy not paying attention in a biology class about hibernation: Master: "Molesworh, what are you doing? Pay attention. Now, what does a bat do in winter? Molesworth: "Er....er.......It splits if you don't oil it Sir."
  14. On the contrary, the covid vaccines have saved millions of lives. I have no doubt that air pollution worsens respiratory conditions and will make the symptoms of respiratory diseases worse, or even reduce resistance to infection. However it is mad to suggest that improving air quality is any kind of substitute for vaccines. That really is tinfoil hat territory.
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