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Everything posted by Ozone

  1. Good evening, all. Think of eV as E as in E=mc^2: the mass of an electron is appx. 9.109E-31 kg, therefore: E=(9.109E-31 kg)(3E8 m/s^2)=8.1981E-14 kg.m^2/s^2 = 8.1981e-14 N (or J). Since 1eV = 1.602E-19 J, 9.1981E-14 J/ 1.602E-19 eV/J = 511741.57 eV or: 0.511...MeV. (a proton is appx. 938 MeV) When a photon meets or exceeds an energy of ~1.022 MeV, it is in the range where pair production may occur. When this happens, the photon converts into an electron:positron pair. These annihilate to yield two photons of 0.511 MeV, which are emitted at 180°, relative to one another. This phenomena is readily observed with gamma spectrum analysis of 60Co. This is an amazing proof to see in the lab. Mass and energy are perfectly conserved and convertable *drools*. This is almost as cool as seeing a muon take minutes to decay when at near relativistic velocities. Cheers, O3
  2. IIRC, the classes you would take in a university Arch. program that relate to this are called "structures". These courses are arranged by material (eg. steel, metal fab.; concrete; etc.) and deal with stress distribution, inertial moments, center of gravity, etc. They represent the "engineering component" of the degree. These courses frequently "weed-out" students, differentiating the "designers" from the Architects (who, like engineers, must become licensed after an intern period following the degree, which is a 5yr program). They use aweful units such as the "kip" or kilopound (which would be 1/2 of a ton). Yech. The calculus required was not the 2 sem, 10Hr variety required of math and science majors (or 16hr for most Chemists involving 3D and diff eq.; or 22 if you also count thermodynamics and quantum). I think that the one-shot, 4hr course was sufficient. Cheers, O3
  3. Look up: 1. TAQ polymerase 2. nucleoside 3. deoxyribose Absolutely not in that order! I am not exactly sure of what you are asking for. Your post implies explicit knowledge of the above, but to me, quoting http://www.mansfield.ohio-state.edu/~sabedon/biol1060.htm, "DNA replication is more accurately described as polymerization. The enzyme which catalyzes this polymerization is called, not surprisingly, DNA polymerase. " Do you need the mechanism? Cheers, O3
  4. Its all good! I still prefer the Curie as a unit; the Becquerel is just too small (unless you are looking at, say, Rn emanated from ground water, which is given in low pCi). Anyhoo, from the link: "Becquerel decided to investigate whether there was any connection between X-rays and naturally occurring phosphorescence. He had inherited from his father a supply of uranium salts, which phosphoresce on exposure to light. When the salts were placed near to a photographic plate covered with opaque paper, the plate was discovered to be fogged. The phenomenon was found to be common to all the uranium salts studied and was concluded to be a property of the uranium atom. Later, Becquerel showed that the rays emitted by uranium, which for a long time were named after their discoverer, caused gases to ionize and that they differed from X-rays in that they could be deflected by electric or magnetic fields. For his discovery of spontaneous radioactivity Becquerel was awarded half of the Nobel Prize for Physics in 1903, the other half being given to Pierre and Marie Curie for their study of the Becquerel radiation." Cheers, O3
  5. Very nice! I agree with replication of old experiments. I have frequently found that there are observations to be made that were not referred to in the original text (or where not observable using the instrument/apparatus of the time). I thought it was Henry Becquerel who "discovered radioactivity" whilst creating the (1st?) radioautograph using various uranium salts. http://nobelprize.org/nobel_prizes/physics/laureates/1903/becquerel-bio.html Cheers, O3
  6. And rods! Oh my! The humanity! The treatise was for fun (and to jog my decrepit memory on a subject that was canned at my university in the mid '90s). Cheers, O3
  7. Fact or Bullcrap? 1. graphite is used as a moderating material, serving to slow down the neutrons that would exist *if* the isotope were capable of spontaneous fission (e.g. large nuclei). The slowing of these neutrons, a process referred to a "thermalization" involves bouncing them off of light weight nuclei, like C or H (water) or D (deuterium in D2O, see CANDU reactors). "Control" involves the absorption of the neutrons to create an actived isotope. The likelyhood of this occuring is referred to as the absorption cross-section and it is measured in Barnes; elements which are quite good at this include B and Cd (heavier isotopes tend to yield fissionable nuclei). 2. There needs to be a large nucleus present to absorb the neutron (if it is moving at just the right energy, eg. thermal neutrons are absorbed by 235U. If the energy is correct, the nucleus becomes unstable and will split to yield two new nuclei (e.g. 92Kr and 144Ba) and a few neutrons. These neutrons, if the material is dense enough (and isotopically pure) will propagate the rxn (critical). If the density is higher still, this may occur at a rate analogous to an explosion (supercritical). 3. The mass of a reflected weapons grade (239Pu) core is ~1kg (reflected implosion) and has an isotopic purity >93%. A reactor at static criticality contains *tons* of lightly enriched material (maybe 8%) or tons more w/D moderation if at natural abundance (~0.75% 235U). The given device takes into account non of this and contains (even with Ra watches, which are very nice a sources) no fissionable material:doh: . I must call bullcrap! O3
  8. If you want the starch, you could: 1. finely divide the material 2. Boil the material in water; this degranulates the starch and renders it soluble. 3. Fractionally precipitate the starch from the water with ethanol (of some other suitable solvent). Alternatively, the liquor can be pressed from the material and re-boiled with s *small* amount of decolorizing carbon (Norit or equivalent) and filtered (buchner funnel over celite) prior to precipitation. There are other ways, but this one is rather inexpensive (particularly when compared to column chromatography over sephadex or analytical GPC). Oh yes, amylopectin (pectin) and amylose are components of "starch". Amylopectin is a highly branched compound whilst amylose is a tighly wound helical molecule. Of interest is that amylopectin is red when complexed with I2 and amylose is emerald green. Merry Christmas, O3
  9. Hmm, my guess is that DominF intends to use yeast as a source of catalase. Catalase *catalyzes* the break-down H2O2 in-vivo to prevent excessive oxidative stress; this is why (besides Fe) that H2O2 effervesces on contact with blood. It does the same for yeast. Try looking *here*: http://www.science-projects.com/catalasekinetics.htm You can also try out metals to decompose your H2O2. These might include Fe2+ (or Fe3+ with a reducing agent), W or MnO2. Comparing and contrasting these kinetics with those acquired with catalase would found a much stronger project. Please, at least try an internet search! It was a trifle to find the link I posted for you here. Merry Christmas (yes, I said it), O3
  10. The KI is not *catalyzing* the decomposition of the H2O2. It is being oxidized to yield I2, which is the source of the brown color. This reaction is a stoichiometric redox and it is the basis for most quantitative redox titrations (usually using starch as an indicator). Catalytic decomposition of peroxide can be seen with enzymes (see catalase) or metals (Fe, Mn, W). Here, a small trace of the catalyst will, over time eventually lead to the near complete exhaustion of the peroxide (decisively non-stoichiometric). For example, peroxide plus Mn yields oxidized Mn and O2 (sometimes quite vigorously); Fe2+ yields -OH, .OH and Fe3+, and W is used in the titrimetric assay for H2O2. Cheers, O3
  11. Wine contains polyphenolic compounds (red much more so than white), many of which are o or p dihydroxyl species. In the presence of a trace of iron (3+, or perhaps Cu2+) and air, a catalytic fenton-type cycle can be established (favorable kinetics occur at lower pH) whereby the "catechol" forms the Fe semiquinone which is oxidized by air to yield the benzoquinone, Fe2+ and H2O2. The Fe2+ catalyzes the decomposition of the H2O2 to regenerate the Fe3+ catalyst whilst yielding -OH and .OH (which is another kettle of fish...). This is just a thought on how oxidation might be done without enzymes or metabolically active whole cells. Sulfite will kill this rxn as well by scrounging your hydroxyl (and peroxyl) radicals and reducing your catalyst. FYI, the practice of wine sulfitation is, IIRC, called "mutage". Cheers, O3
  12. Some issues with connectivity... The oxidation states must also make sense. For example, Calcium hydroxide is given as Ca(OH)2 because calcium has two electron holes (2+) in its outermost shell and the OH "radical" has one electron to share (1-). This is due to the fact the O is 2- and (in this case, look up hydride anion) H is 1+; the sum nets a 1- charge. These must balence as well which is why there are 2 OH to each Ca. These charges are given on the periodic table, e.g. alkali metals 1+, alkaline earths 2+, etc. This gets somewhat sketchy toward the right of the table where empty shells> (see B, see also hypervalency) can exist. So, simply balencing the number of each atom on each side of the arrow is not all you have to do. This will require memorization or better, a thorough understanding of the Periodic table. Learn it, live it, love it, and your there. Cheers, O3
  13. Check out the difference in electronegativity between the As and I. This should give you a good idea, quickly as to the nature of your bond. Given the distance between them on the Periodic table, your probably screwed. Cheers, O3
  14. You could try to get a job with the university. Most larger schools offer tuition waivers for up to 6 hr of class per semester. While somewhat slow, this method is effective and can keep a modest wage in-pocket. This is what I am doing to get through the Ph.D. I am not sure how well it will work with only a high-school diploma, but so far as I know, the benefit is sound regardless of position (research associate = custodian for purpose of acquiring the tuition waiver). Best of luck, O3
  15. Hello, Whether you had calcium acetate (calcium ethanoate, Ca(OAc)2) or the free ions Ca++ and 2-OAc will depend upon the pH of the observed solution. I would like to suggest looking up and learning about pH (and pKa, leave out activity, for now:eyebrow: ). Once learned, this can help you to predict what-reacts-with-what (and at what pH it might occur) and what products you will have (at the observed pH). Cheers, O3
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