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John Cuthber

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Everything posted by John Cuthber

  1. I'm pretty sure that chlorine is a stronger oxidant than sulphur so that reaction is, if anything, less likely than H2S blackening PbCL2. Burning octane isn't a reaction, it's lots, probably hundreds of reactions. Each of them IS reversible. Did you imagine that there was some sort of concerted attack by a dozen or so oxygen molecules? Every step in the free radical chain reactions that occur in burning octane is reversible. Getting the whole sequence to run backwards is energetically possible but entropically disfavoured.
  2. I think that the problem is that I don't understand some of the things there and I'm fluent in English. I think it's not a coincidence that they have marked with a §. Those phrases are certainly not standard English. For example, what does vegetal mean in "Related Coursework : Vegetal Improvement and Genetics of the Populations " I have some idea what "§ Analyses and interpretations of gel on the chromatograph " means but I'm not sure, I think a biochemist or molecular biologist would be able to help. Thigs like "§ Castration of corn § Dating of female flowering " will get through a spell check without any problem - all the words are correct, but I doubt that they mean quite what was intended.
  3. A typical bolt is (from wiki) about 500MJ. On average it hits about 100 times a second. That's quite a bit of power- 50 GW or so. The world uses about 3600 GW of electricity at the moment. (from this site http://www.cslforum.org/japan.htm) Lightning isn't going to solve our problems. If it was easy to harvest then it could make some small contribution but it's a non starter really. Pity.
  4. "Van Halen belts" http://en.wikipedia.org/wiki/Van_halen 'nuff said.
  5. You can olny focus the laser down to a spot size of roughly half a micron.This is huge compared to the individual base pair (about a third of a nanometre). If you had an Xray laser then you could possibly do what you suggest but sequencing DNA isn't that difficult; it's a lot easier than getting an Xray laser. Even if you could get the xray laser you would still have problems. First Xrays destroy DNA. Secondly the signal from just one DNA molecule would be too small to see properly. You would need lots of molecules all lined up and I can't see that being easy. Even crystaline DNA isn't that well aligned.
  6. IIRC telluric acid is a strong enough acid and oxidiser to dissolve gold so there is at least one acid that attacks gold. The strongest acid you can get in any decent concentration in water is H3O+ (or, rather, its hydrated forms) To get stronger acids you need different solvents. Flurosulphonic acid is already strong but adding a fluoride acceptor like SbF5 to it makes it even stronger. http://en.wikipedia.org/wiki/Magic_acid
  7. Just in case anyone isn't familliar with the term http://en.wikipedia.org/wiki/Bitter_solenoid Anyway, if you are using kilovolts to power magnets then I hope they are pulsed. That makes some of the problems more difficult (like building the power suuply and insulating the coil) but it means that the physical strength of the thing can be lower. What is the application?
  8. "What would be interesting is natural CO2 emissions were overlaid, so we could see exactly where all the CO2 was coming from and how it compared with man made emissions" Well, the CO2 levels used to be constant at about 300 ppm, now they are rising. It's fair to assume that the difference is due to mankind. If that's true then the net contribution from natural sources is nil. Pointing out that the fraction of CO2 emisions from air transport is fairly small is one thing. Recognising that it is due to the actions of a relatively small number of people is another.
  9. "Sorry, to sound naive, but why is CO2 a pollutant?" Well, the obvious answer is to sit you in a room full of it; it's toxic. Just because it's a natural product of metabolism doesn't stop it being a pollutant. People take considerable care to ensure that the sewers are kept separate from the water supply. When they fail, for example due to floooding, it's called pollution. "Seems a strange pollutant that encourages beneficial growth" Yes, at first it does seem strange; it's called eutrophication. It's a problem because it upsets the balance of the system it enters. Nitrates and phosphates do it too.
  10. It's a bit "old school" but that reaction works quite well. The other dominant product is sulphur vapour but I don't think that would blacken PbCl2. I don't see why it's not the conditions I described; I passed H2S over moist PbCl2 and it went black. In principle all reactions are reversible so while it's fair to say that the reaction would usually give lead chloride and a nasty smell it can be driven the other way.
  11. I thought that the fact that the H2S could carry away the HCl would force the reaction to give PbS. Anyway, I tried it and it did. H2S from heated sulphur, parafin wax and sawdust in a test tube blackened a piece of paper smeared with wet PbCl2.
  12. I wonder; if you got some nice white PbCl2 (I guess damp would work best)and passed H2S over it would it go brown?
  13. Well, it should work but lead sulphide is so insoluble that the reaction might be a bit slow and, with dilute enough acid, it might not work at all or the reaction might even go backwards.
  14. I think anyone who can honestly say this "I LOVE research and I LOVE being the first person to find out something new- knowing even before the PI... it's such a rush. " is probably a scientist, but I wonder, what's the definition?
  15. Alkaline hydrolysis of nitriles gives the amide then (with addition of more water) the acid and ammonia. RCN +H2O --> RCOHN2 RCONH2 + H2O --> RCOOH +NH3 Obviously, the acid reacts with the NaOH to give the Na salt.
  16. I think that a circle is all the points at a given distance ® from the origin. In 1 dimension it's a bit meaningless but x^2 =r^2 works (2 points at + and - r) In a plane you get a circle x^2 + y^2 =r^2. A sphere has x^2 + y^2 + z^2 =r^2 I's even go on to speculate that in 4D you would need to add w^2 as well.
  17. I8science didn't seem pleased with the results they got from posting here. I doubt they will be back.
  18. (lights blue touch paper) Got mine long ago when they weren't so easy.
  19. OK, that seems to be a picture of a female; how do we know it's you? Mind you, since I'm a Martian I think the annonymity of the internet is very useful. You earthlings seem very prejudiced about those of us with green skin.
  20. Since the ancient Romans didn't have soap but did have a warm climate I'm not sure they would have noticed the after effect of using spoiled urne as a detergent. Lots of perfume was probably a good idea.
  21. I think the only way to conclusively prove it would be to get a large un-exposed population, inoculate half of them with HIV and see who went on to develop aids. I don't think it's weird that nobody has done that experiment, so I don't think it's weird that there's no conclusive evidence. Biology seldom produces strictly conclusive evidence. Everyone knows that smoking is bad for you but we have all heard of people who smoked for decades yet lived to grand old ages. Biology is awkward that way.
  22. It's a lot easier to make 2 lenses that are both reasonably powerfull than to make 1 that's very powerful. Combining the 2 easy lenses gives the same magnification with less hassle.
  23. I too didn't do a lot of homework but did OK in exams- perhaps I'm a genius perhaps I'm just lucky. The difference is that I also didn't ask my friendsto do my homework for me; not because they wouldn't have helped, but because I could have done it perfectly adequately myself. This guy seems to be asking us to do it because he hasn't a clue. I didn't do my homework because I knew that I understood the stuff and would do OK in the tests so why bother to waste my time going over it in my own time. That's a really important difference.
  24. Never mind CO poisoning. Explain what you mean by "It is possible to model the cell in terms of one variable, i.e., hydrogen bonding. " Trust me, the lack of experimental data isn't the real issue here as far as I can see; it's the fact that you don't seem able to explain what you are on about.
  25. If I ask the same question a 3rd time will you get the message and answer it? What does this mean? "It is possible to model the cell in terms of one variable, i.e., hydrogen bonding."
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