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John Cuthber

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John Cuthber last won the day on February 12

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About John Cuthber

  • Birthday 11/10/1965

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  1. If the V2 at 5760 km/h was above about 15000 feet (depending slightly on the weather) it would be hypersonic. https://www.fighter-planes.com/jetmach1.htm
  2. I have used PEEK fittings at 5000 PSI and above.
  3. It's still "sort of " right. Brown goggles will not protect you against a brown laser beam- because it doesn't exist. UV blocking goggles are likely to be yellow. IR blocking ones are likely to be blue/ green. If they block by reflection they (1) are not a good idea and (2) they look really shiny/ mirrored . It's not a good idea because reflective coatings are typically thin and easily damaged. In general it's not a great idea to judge the goggles by their colour.
  4. According to this, you should be able to find "moon dust" with enough potash to grow plants. But without combined nitrogen you are stuffed. https://sites.wustl.edu/meteoritesite/items/the-chemical-composition-of-lunar-soil/
  5. The range of frequencies we can see is (just) less than an octave. We could possibly just about see 400 THz. 401THz and 801THz. The closest thing to relevant that I can think of is that both getting the sum of two frequencies, and the photochemistry of photosynthesis rely on 2 photons. A single visible photon doesn't have enough energy to split water.
  6. Anyway, lets be a bit more clear. The action spectrum for photosynthesis has been measured. https://ib.bioninja.com.au/standard-level/topic-2-molecular-biology/29-photosynthesis/action-spectrum.html There's a big trough for green light- which is, at best, poorly absorbed (even with the help of the carotenoids). So it makes sense to focus your efforts into making red + blue light. The most likely fate of a green photon near the bottom of the graph is that it will be wasted as heat. If you were making coloured light by starting with white light, and filtering it there would be no point (except that taking out the IR might prevent overheating). But with LED lighting, you can selectively generate the colours that work best. Also, none of this has anything to do with heterodyning light.
  7. Plats are, in general, green. They reflect green light so they can't absorb it. So any green light emitted by your LEDs is wasted on the plants. As you say, you need a lot of light to get plants to grow well. But there's no point shining green light on them. So it makes sense to produce lights that only have the blue and red bits of the spectrum. People (generally) have three different colour sensors so colour rendering for people is different to efficient illumination of plants.
  8. Cow manure. Seriously- The farmers used crushed old plasterboard as "bedding" for cattle. (It was cheap) That led to a dangerous enhanced production of hydrogen sulphide in slurry pits.
  9. You can use sulphates as oxidisers, if the fuel is a strong enough reductant. The reaction of calcium sulphate and aluminium is well documented. I should probably say something like "don't try this at home" but
  10. I was offended, but nevertheless amused to see a graffiti addition to a sign asking for people to help funding the spastics association (now renamed Scope, I think). They turned " Help spastics" into "Help! spastics!". Chemistry (and I guess other) journals are full of instances of a particular type of error. The material was analysed using chromatography. There's only one thing there that can be doing anything, and that includes chromatography... Did the material analyse itself? Compare it to "The celebrity was photographed using cocaine". My all time favourite is from a wartime newspaper. The punctuation etc is perfectly correct. A headline that was drafted as British army push bottles up Germans had been repositioned as British army push bottles up Germans And then there's English spelling.... but that's another subject.
  11. It may be easier to trawl through the patents than to try to work it out.
  12. So, not the cheap ones like Na Ca , K... You have to shift about 5 tonnes of water to get a gram of Lithium. That's on the market at about $17000 per tonne, $17 per Kg 1.2 cents per gram Good luck. Getting Mg is just about worth it at 1300 ppm. So there's about 6500 times as much Mg as Li. It's just possible that a plant that extracts the Mg could, without too much additional work, extract Br, Sr maybe others.. Since the Mg production is already paying for the pumps, and workforce, it might be possible. The people who know about it either are already doing it, or know it can't be done.
  13. It's impossible to tell. What set of digits are the sequence chosen from? all the digits 0-9 Binary digits 0 and 1 or even hexadecimal digits 0 to F.
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