John Cuthber
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Everything posted by John Cuthber
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"for copper electrorefining is 0.0 V. In practice, overvoltages at the anode and cathode and the resistance in the electrolyte and electrical system result in the need for an applied voltage of approximately 0.3 V. " From http://doccopper.tripod.com/copper/er.html Or 0.15 to 0.3V from http://www.ct.ufrgs.br/ntcm/graduacao/ENG06631/5-b_copper.pdf I recognise those are for copper, but silver's not that different. So the energy use is roughly a tenth of what you said. 0.02MJ / mole Now a MW Hr of (domestic) electricity is 3.6GJ and costs- as you say about 150 Euros So that's 4 cents per MJ So the electricity cost is 0.02 MJ/ miol times 4 cents per mol which is 0.08c per mole Roughly 10 moles to the Kg so the electrical cost is about 1 cent per kilo or about 10 Euros per tonne. Today's price is about 500 euros per kg or roughly 500,000 per tonne. Essentially, unless you can recover 90% or so of the energy that you put into evaporating the metal, it's not worth it Electro refining at about 0.02 to 0.05 MJ / mole is going to be cheaper than boiling at 0.3 MJ/ mole, even when you allow for gas being roughly a third the price of electricity (on a J per $ basis).. Running it in a stream of argon means you also spend energy heating argon.
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Well, it's certainly sensible for any stable element. Whether it's worth it for a steak is debatable- there might be some stupidly rich tourists in space.
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Unless you expect it. Castles were built with staircases with an "odd" stepp in them to trip enemies who were climbing the stairs. I learned about this interesting fact in a talk about the safety of modern stairs where , as they pointed out, badly made stairs are still killing the unwary. Here's a trivia question for you ( the answer is at the end of the post) Roughly how many people are killed by falling on stairs each day in the UK? Interesting fact for the day. If you have a staircase where the steps are uneven you can always make it even by adding planks (of various thicknesses) to the steps. This is an important result because adding to the treads is easy but taking stuff away is hard. It's also (I think) always possible to make all the steps the same "length" as well. So there really is no excuse for badly built stairways. (About two, btw- did you guess right?) Our brains are pretty good, but we often rely on reflexes which don't use the brain. I'm not sure which category this phenomenon falls into . I'd be interested in finding out. I'd be even more interested in knowing how they found out.
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Anything we can do an asteroid can do better; an asteroid can do anything better than us. Seriously, the gravity well of taking something away from Earth is so expensive in energy that it will make sense to get any element from somewhere smaller more or less regardless of how common it is.
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True. (And, personally, I think he should have gone with turquoise or peach as the 7th. Who seriously thinks indigo isn't blue?) The important point is that 1 exceeds zero. So is just plain wrong regardless of Newton's numerology
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The word Clinical has a similarly odd origin. It means bedside. It's related to words like recline and incline. It also ties in with geological "beds" as in syncline.
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Newton would disagree, having put indigo and violet in the space between blue and UV. There's undoubtedly some light produced below 400nm, but not very much. And, for what it's worth, 400 nm is visible. The exact "start" of the UV is rather poorly defined. But your implication is that the designers chose a phosphor that only works "by accident". Not only that, but there is direct evidence that the phosphors absorb visible (blueish) light. Have a look at a white LED when it's not running. It looks yellow. Do you have some extraordinary evidence?
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The best street lighting is probably the one that gets the local politician re-elected at the lowest cost.
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I take it that you understand paraphrasing https://www.theguardian.com/us-news/2019/nov/06/trump-impeachment-inquiry-ukraine-testimony-bill-taylor
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Kind of misses the point. It's reasonable for Trump to say "You should look into this" It is not reasonable for Trump to say "You should look into this or I will withhold US government support for your country" Do you see the difference there? Have you missed all the references to "quid pro quo or did you not understand them " ?
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Are you aware that two wrongs don't make a right?
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Higher beef prices are not a vote winner. It is, in principle possible to split antibiotics into two groups- those used in humans and those used for animals, but it's an imperfect solution. If we found it, there would be immense pressure on doctors pressure to screw it up in the same way we did with penicillin etc. I'm intrigued by the idea of using phages, though I recognise that they suffer from essentially the same issues. One thing that would help would be if doctors had the freedom to prescribe placebos or to be more honest to their patients. Mr Smith "Dr I have a cough and I'd like something to treat it. Dr "Sure, here's a prescription for some cough syrup " (while writing out Rx for "simple linctus" which works just as well as anything else and costs the NHS about a pound per gallon). Mr Smith "is it an antibiotic?" Dr "No, but there's a nine out of ten chance that your cough is viral and so an antibiotic would be useless. On the other hand, there's about a 1 in 3 chance that the antibiotics will upset the natural balance of bacteria in your guts. So, overall, an antibiotic is about 3 times more likely to give you the s*Its than to do any good."
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Yes,. I invite you to consider, for example, the workings of a "white LED" where an LED actually emits blue light and some of this is down converted to the rest of the visible spectrum by some sort of phosphor.
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Good luck making it cheaper than electrorefining. In theory the voltage required for electrorefining is near zero; the electrolyte is reusable and the process happens near ambient temperature. Also, there's not much demand for pure silver. YOu can reuse the alloy as it is. What you need is a cheap simple way to turn pure silver into the alloy.
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How have you ruled out blue?
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Air is transparent to any wavelengths of UV that would escape the plastic package of an LED. Incidentally, as far as I can see, nobody has mentioned purchase and running costs (except, arguably, Dimrepr).
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How?
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You don't understand how science works.
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Religious and Political correctness triumph over science
John Cuthber replied to MigL's topic in Politics
It's an interesting idea. Imagine that some state decided that you could get the "right" answer by saying " my religion tells me so". Imagine the pupils studying and passing exams under those conditions. And then imagine them looking for work. Employer " I see you sat your exams in such and such a state" Candidate "Yes, that's right" Employer- "That's the state where you can pass exams by getting the wrong answer, isn't it? Candidate "Yes, that's right" Employer " Next candidate please". Now, I think that most students would recognise this problem quite quickly and would actually object to any such absurd legislation. -
There are a couple of bits of the human skeleton which are not "attached" to the rest. IIR|C the hyoid bone is one. So, in a model skeleton, it needs a "bridge" of some sort to hold it in place. There would need to be some way to distinguish that bridge to make it clear that it's not a bone. Making it red would be one possible option.
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Science makes progress by trashing ideas that don't work. If you are not happy with that, try another field.
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Manuka honey is a very very expensive way to buy sugar containing variable traces of nothing-special antimicrobials. Why not just go to the local supermarket or pharmacist where they stock a wide range of antibacterial products that are known to work reliably? Some are even perfumed with essential oils. Why specify "natural". Natural does not mean "good" or "safe".
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Honey is an expensive way to buy sugar. High concentrations of sugar will stop many or most bacteria- because there isn't enough water for them to thrive. However, that's not going to work well as a hair product- it's too sticky.
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No. Everything is toxic; it's a matter of dose. Also why is your text in pale grey on white?
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Yes it does. I have a dead soldering iron bit which says that it does... Also http://www.farnell.com/datasheets/315929.pdf Lithium / lead alloys (which have seriously different sized ions) are being considered for use in nuclear reactors. The only way to find out if lanthanides attack tungsten is to try it.