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yangxu's Achievements


Quark (2/13)



  1. correct me if I'm wrong, based on what I've learned so far, antibiotics are either produced by fungi, bacteria themselves, or manufacturers... the artificially made ones includes anti-metabolites, analogues, etc.
  2. bacteria identification is not revealed through Gram stain, it only divides them into Gram pos or neg bacteria, identification requires a dichotomous key with several biochemical tests designed to match certain characteristic traits of common bacterial species.
  3. My question is if there is a war between China and Japan, and US gets involved, how much is US willing to spend its money and time in this war? If the war can't end quick and become a prolonged battle, I doubt US will support Japan till the end, a lot of US industries rely on China for profits, and should it lose China as its economic partner, US will encounter some serious problems in its economy.
  4. seems like a lot of cellular process contributes to aging (eg. non-functioning telomerases, etc), personally I'd go for genetic modifications if human really has the desire to live up over 100 yrs, taking drugs will probably cause side effects.
  5. I'm currently a student in the molecular bio faculty, but the topics that are introduced to us right now are pretty scarce, enzymology, proteomics, molecular physiology, etc. and none of them actually goes into great details to get me interested in a particular field... is it because molecular bio is a generalized name for all these categories and that I have to choose one of the streams after I graduate in order to continue studying under this field?
  6. well, IQ tests are based on logic and intepretation, but how the writer designs the question so everyone understands what is required to be answered is a whole new problem... there are people with poor English comprehension skills who completed the IQ tests and got 75 or less, but that could just be the wordings and vocab limitations in the questions.
  7. I remember there is a statistic report saying the children who are exposed to classic musics score better on math tests and other subjects... there might be a lurking variable that controls this, but I do think there is some relation between musical impacts on children and their academic success...
  8. Can anyone provide me an internet source of any recent science journal articles that relate to tools or techniques used for DNA or RNA? I'm not sure where to start looking, most links I got in google are just specific texts from a university's lecture... please give me some suggestions, thanks a lot!
  9. The National AIDS Bahavioral Surveys found that 170 individuals in its random sample of 2673 adult heterosexuals said they had multiple sexual partners in the past year, that's 6.36% of the sample... but my prof said this is biased, my guess is that the survey concerns a sample consists of only adults who are heterosexuals and based this random sample's result to cover all types of sexual preferences for adults in the community... is this a reasonable explanation? Please enlighten me, thanks a lot in advance!
  10. I don't understand how that universe = blackhole came up... but if we are living in a blackhole, how is it possible that we can withstand its gravitational force and still live normally? If universe = blackhole, there must be another universe outside ours to include it in... No one has ever entered a blackhole, but I doubt blackhole's internal regions are different from the external unless the force changes dramatically; to me, blackhole is not a typhoon where in the typhoon eye, there is no wind... even if you get into the centre of the blackhole, I don't think you'll experience 0 gravity...
  11. sorry, just wondering... doesn't HF belong to hydrogen bond group? I thought hydrogen bonding is like a special type of bonding that doesn't belong to covalent or ionic bonding category... plus I think ionic means that you have to transfer your entire electron from one atom to another, but hydrogen bonding isn't something that obeys that rule...
  12. I just performed an analytical chem lab yesterday and it was about gravimetric analysis of chloride, during the lab, the TA gave me a question that puzzled me, "if a solution contains both I- and Cl- at about 0.1M, can we determine the amount of Cl- and I- independently by using gravimetric analysis?"... my guess is no, but I don't know how to explain this, can someone please provide an explanation to this question? thank you very much!
  13. thank you so much wolfson!
  14. hello everyone, I was trying to do a practice exam last night and come upon this question about rate determining step, I'm confused on how you can tell which step is the rate determining step from a table that gives you rates and concentrations for individual reactant, here's the question: consider the following data for the reaction: H2O2 + 3I + 2H -> I3 + 2H2O [H2O2] [H] Rate I. 0.100M 5.00E-3M 1.00E-2M 0.137M/s II. 0.100M 1.00E-2M 1.00E-2M 0.268M/s III. 0.200M 1.00E-2M 1.00E-2M 0.542M/s IV. 0.400M 1.00E-3M 2.00E-2M 0.108M/s Two mechanisms are proposed: I. H2O2 + I -> H2O + OI OI + H -> HOI HOI + I + H -> I2 + H2O I2 + I -> I3 II. H2O2 + I + H -> H2O + HOI HOI + I + H -> I2 + H2O I2 + I -> I3 which of the following describes a particularly correct mechanism? a. mechanism I with first step as the rds b. mechanism I with second step as the rds c. mechanism II with first step as the rds d. mechanism II with second step as rds e. none of the above the answer is a, but I don't know how it's obtained, I tried to solve for the rate law in the format of Rate = k[A]etc. but I still can't tell which step is rate determining, could someone please help? thanks a lot!
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