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Cake day: June 29th, 2023

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  • I know of a manager who unironically believes this for internal corporate technical reports (ours are academic style and more rigorous and formal than they need be…). It’s not quite to this extent, but I’ve overheard conversations where the manager apparently can’t fathom why their subordinates are incapable of double digits over a year.


  • Do not power law fit your process data for predictive models. No. Stop. Put the keyboard down. Your model will almost certainly fail to extrapolate beyond the training range. Instead, think for at least two seconds about the chemistry and the process, maybe review your kinetics textbook, and only then may you fit to a physics-based model for which you will determine proper statistical significance. Poor fit? Too bad, revise your assumptions or reconsider whether your “data” are really just noise.

    Always run qNMR with an internal standard if you are using it to determine purity. And, as a corollary, do not ignore unidentified peaks. Yes, even if it “has always been that way”.

    DOE models almost certainly tell you less than you think they do, especially when cross-terms are involved, or when the effects are categorical, or when running a fractional factorial design…








  • Ugh I had an older colleague, a PhD organic chemist, who was absolutely convinced that soy would make me (m) infertile. I ordered tofu once when out to lunch and he would not stop warning me to “be careful” and to be mindful of starting a family and “you know those studies.” When I mentioned that the consensus was at best inconclusive and most likely there is no such link, he said that no, “they” definitely showed that excess soy is bad and that he worried about my reproductive health. Like dude even if eating tofu did cause reproductive health issues, mine is none of your goddamn business. On the other hand, the same guy is also convinced that BPA (another estrogen mimic used esp. in certain plastics) concerns are a total hoax because “they did bad science because their sample containers had BPA in them and it leached into the urine samples giving false positive.” Also something about the only evidence of it binding like estrogen was that someone glanced at a crystal structure and halfassedly thought it looked like it might fit and rolled with it for career reasons. Like, I don’t know, man, maybe a couple studies used containers made with BPA, but most probably didn’t. I haven’t read them, but I know you didn’t, either. Also, you’re literally a petrochemist, you know BPA is mostly used in polycarbonates, and lab plastics, especially for analytical work, are mostly polypropylene or polyethylene designed to avoid exactly this kind of leaching. Honestly.


  • Tbf sometimes it’s hard even for organic chemists because the authors will just put an abbreviation of a non-standard variation of the name of some named reaction over the reaction arrow and then proceed to draw the product in a completely different conformation from the starting material, leaving you trying to work out which carbon is which in the world’s most annoying game of spot-the-difference (or in many cases spot-the-similarity).




  • ornery_chemist@mander.xyztoScience Memes@mander.xyzHarsh
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    3 months ago

    Ya but the moon covers at best only about 10 ppm of the sky’s area so given a random direction within the hemisphere defined by the sky in which the moon is visible and traveling in a straight line you have a roughly 99.9990% chance of missing so that’s understandable really.


  • Roughly a truncated cone with diameters ~7 nuts and ~9 nuts, and the cup is ~12 nuts high (loose guesses, it is hard to tell due perspective and nuts of different sizes). Throw in an extra layer to account for the heap at the top (which is a dome taller than 1 hazelnut, but treating it as a shorter but full layer should give some error cancellation) to give a height of 13. The volume of a truncated cone of those dimensions is ~657 cubic hazelnut diameters. Random sphere packing is 64% space-efficient (though wall effects should decrease this number) giving a total of 420 nuts (nice).

    Multiple edits for clarity and typos.

    Answer

    This ends up being about 5% lower than the true answer. I’m surprised it’s that close. This is in the opposite direction from what I expected given wall effects (which would decrease the real number relative to my estimate). Perturbing one of the base diameters by 1 nut causes a swing of ~50, so measurement error is quite important.



  • Ah shit are you me a few years in the future? Currently in the corporate phase, only, instead of my PhD convincing people that I know what I’m talking about, I get told to pound sand and, for everything I do, every slight change I make, consult our minored-in-chemistry EHS focal points whose only hands-on lab experience is neutralizing bicarb with food-grade acetic acid solutions inside a molded clay vessel. And, for “reactive chemistry” concerns, consult the ChemE “expert” in another time zone who can’t read even structures of organic molecules.

    EDIT: actually in retrospect I don’t believe that they have done even the bicarb thing because it involves gas evolution, which is a big no-no.


  • ornery_chemist@mander.xyztoScience Memes@mander.xyzYAYAYA CONGRATS!!!!
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    5 months ago

    The woman is covered in 3 different kinds of power series (all Taylor, but one is general and the other two are specific to 1/(1-x) and ln x, respectively) that certain kinds of scientists (presumably personified here by the man) love to swap in for more complicated terms by waving their hands and chanting “first order”. Truncated series give fugly equations a more tractable form by applying certain assumptions (e.g., x is very small, x is very large, or x is fuck-it-we-ball).

    EDIT: nvm apparently this is a pop culture reference.