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John Cuthber

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Everything posted by John Cuthber

  1. Tehnically, you need to consider the effect if the self ionisation of water which is where the Kw comes from but it will be a small effect, you can probably ignore it unless you need a very high accuracy (rather more accuracy than the Pka values you have been given). You do need to calculate logs (rather than antilogs) but I can't see what use a titration would be. If Riogho would care to enlighten me on that I'd be happy to here about it; otherwise perhaps he might care not to complicate the issue. Ddatuf, did you understand the stuff on that wiki page? It tells you how to do the calculation, but, like a lot of things, it might not be a very clear explanantion.
  2. What you really need is one of these, but the price is horrible. http://cgi.ebay.com/BioMax-TranScreen-HE-Intensifying-Screen-Kodak_W0QQitemZ330117601773QQihZ014QQcategoryZ97133QQrdZ1QQssPageNameZWD1VQQtrksidZp1638.m118.l1247QQcmdZViewItem
  3. The typical sulphur content of wood is about 0.01% so the yeild of DMSO from timber would be, at best, pitiful. The reason it's dome comercially is that lots of sulphur is used in processing the paper pulp and some of this sulphur is converted to DMSO. If you look here http://en.wikipedia.org/wiki/Kraft_process you will see that this isn't the sort of thing it would be easy to do at home.
  4. http://en.wikipedia.org/wiki/Henderson_hasselbach
  5. Have you tried film rather than paper? Typical film exposures are much less than a second, typical exposures when printing are a few seconds. That might give an increased sensitivity.
  6. "What, the islands generally known as "Great Britain" don't consist of England, Scotland, Wales and Ireland? I need a new atlas." Looks like you do.
  7. "Well, if they can make a conclusion that 80% of the universe's matter is missing (dark matter), then they have to have some way of computing the total amount of mass. The total amount of mass is not an infinite number, because x/80% does not equal infinity." The mass of the universe can be finite without saying anything about how big it is.
  8. I don't know about HCN but I can't smell CH3CN.
  9. OK, The use of the "Christian" symbol is taking the piss and that's neither big nor clever. On the other hand, if you knew an adult who believed in the Tooth Fairy or Father Christmas, wouldn't you expect them to get the piss taken? Not one of humanity's more glorious traits, but a common one. Also, are these people who complain about a symbol the same ones that I see wearing a model of a corpse nailed to an ancient instrument of torture? Is a fish with a word in it that offensive?
  10. If I were a physician who felt that the ending of a patient's suffering was in their best interests, and was working in a country where euthanasia weas permitted by law then, as far as I can see, the last version of the hippocratic oath there (and the fact that there are 3 different versions is rather telling) wouldn't rule it out. "That you will be loyal to the Profession of Medicine and just and generous to its members." is irrelevent. "That you will lead your lives and practice your art in uprightness and honor. " If I thought ending a life that has become a burden is morally correct, then doing so would be honourable. "That into whatsoever house you shall enter, it shall be for the good of the sick to the utmost of your power, your holding yourselves far aloof from wrong, from corruption, from the tempting of others to vice." So long as I think it's the right thing to do, in the patient's best interest and that I'm not doing it explicitly for money or personal gain euthanasia still looks OK. "That you will exercise your art solely for the cure of your patients, and will give no drug, perform no operation, for a criminal purpose, even if solicited, far less suggest it. " In the case of a terminally ill patient it's possible that all I can do is eliminate their suffering. That's only symptomatic relief rather than cure but the difference is a matter of definition. The patient will die anyway; euthanasia cures their suffering. "That whatsoever you shall see or hear of the lives of men or women which is not fitting to be spoken, you will keep inviolably secret." Doesn't enter into this debate. Euthanasia is a difficult topic but that oath (which is arbitrary anyway) doesn't make much difference. The others definitions are equally troublesome; the first breeds nepotism but prevents much of what would be considered normal medicine. Most drugs are deadly. Abortion is now accepted in most societies.
  11. A tank full of CO2 would melt to a liquid under pressure, but the idea is still OK. It has been used for model aircraft and I guess you could use it for other things. Whether or not it's an improvement on compressed air is another matter but at least the pressure would be relatively constant as you said. You might need to heat the tank to get the CO2 to boil fast enough.
  12. At least part of the effect is this. http://en.wikipedia.org/wiki/Cavitation
  13. Borodin, is it a reaction mechanism you are looking for?
  14. You can get the data from the fine structure of an IR spectrum, but the easy way is to look at the microwave spectrum. That gives you the rotational frequencies. Given the masses of H and Cl you can work out what bond length corresponds to the right moment of inertia for the measured frequencies. Another way, more useful for solids is to look at the Xray diffraction patern. You can do similar electron diffraction measurements on vapours.
  15. It seems we are condemned to make the mistakes of the past all over again. Long ago a colleague told me of his old boss who had worked as an anlytical chemist. A really famous toy manufacturer made the point that heavy metals (Cd rather tha Pb) were well stuck into the toy and couldn't get into the child. The chemist took one of the building bricks and chewed on it for a while then spat into a test tube. The yellow colour of the shredded plastic was perfectly clearly visible. As he pointed out the next tep would have normally been that the child who had been chewing on the brick would have swallowed the powdered plastic. That would have led to the plastic being leached with dilute acid. A quick experiment showed that plenty of Cd could be extracted this way to be a chronic poisoning hazard to small children. Eating many plastics is pretty harmless because they are not digested. Small children, to whom many toys are targeted are not aware that eating plastic is bad; they chew everything. Didn't you know that?
  16. OK, How do you propose we avoid a flu pandemic? All we can hope to do is mitigate the effects when it happens. Of course no govt is going to allocate the resources needed to do that unless the people want it (well that's the idea of democracy- your mileage may vary) so it's a good thing that the likes of WHO tell people. The papers hype it up because that's what they do for a living.
  17. Do we have any wannabee epidemiologists here who would care to comment on Mr Jackson's post above in light of three facts. Over the last 200 years we have generally been exposed to ever increasing and more complex fields. We are living longer than ever before and enjoying better health than ever. In less developed nations the exposure to magnetic fields is smaller yet the health of the population generally worse.
  18. There have been toxic nanoparticles since the first forest fire- probably since the first volcano. We don't seem to be dead yet. Not grounds for complacency but certainly an argument against panic.
  19. Interestingly that idea would mean that life could never get started because all the stuff started out as "inorganic". Another possible conclusion is that the assertion is simply false. Since I'm here and alive I know what I'm going to believe.
  20. Remember all the fuss the WHO made about smallpox? What was the point of that? Nobody gets smallpox anymore. I think that was a similar screwup by the WHO. (Yes, I am using irony here) Seriously, just because the flu pandemic hasn't happened yet doesn't mean that it won't.
  21. I'm quite certain that colds sometimes kill people, that's why I put the word "usually" in my post. A few visuses are known to cause cancer but I don't think the cold is one of them.
  22. I think it's Le Chatelier's principle and I'm familliar enough with it. However, while an excess of one reactant will drive a reaction to completion there is still the question of which one you use in excess. They could chose more C or more TiO2
  23. Part of the reason we can't cure the common cold is that it isn't worth it. It makes more sense to put medical resources into things that kill rather than annoy as the cold usually does.
  24. Just for the record I looked up how they make the stuff. They use an excess of carbon and generate CO as the by product. I don't know why they do it that way but I guess C is cheap and they want to convert all the titania to titanic chloride.
  25. Until they reach terminal velocity, then they stay at the same distance.
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