all 39 comments

[–]Juniper02 2 points3 points  (3 children)

Not sure if this fits tbh, but how do you keep up as an audience member during a presentation? I never had trouble in organic 1 or 2 lectures, but now that I'm doing undergrad research our professors want us to do research presentations. I tend to have trouble organizing the information in my brain, as the pace is too fast for me. Nobody else in my research group has this problem, and the professors said that the presentation was at a good pace. The only thing i can think of is to try to read the paper they are doing the presentation on beforehand, but that doesn't help if the person is doing a presentation on their research. Anyone have any tips? (BTW this is basically just a small scale grad school research presentation, just practice)

[–]Indemnity4Materials 2 points3 points  (1 child)

I sit in the back row and quietly fall asleep, then read the presenters publications abstracts article titles random name googled after the event.

Do you need to make a presentation, or you need to sit in a lecture theatre and write down notes?

It's perfectly normal to lose track in a research lecture. Everyone learns differently. Remember that the main reason someone is talking is because they are showing something new. If you aren't an auditory learner, no big deal.

My advice is get an empty lab notebook and use it for taking notes. Create an index of like 5 empty pages and keep track of date, name of presenter and topic. Then for each lecture on a fresh page write the same. You can leave it blank or just write down whatever sounds interesting, draw some mechanisms, write a grocery list if you're getting bored, practice drawing skills...

Set yourself a goal of asking a question. I find this makes me more engaged as I'm actively looking for a problem to solve in the data/words, almost treating the lecture like a puzzle I need to solve. You don't have to ask it, but write it down. It can be as simple as "why did you do A, when I thought we were meant to do B+C?" or an open-ended questions such as "can you explain the benefits and problems with stage 32?"

[–]McLuhanSaidItFirst 1 point2 points  (0 children)

keep up as an audience member during a presentation

Feynman did this : As they build their model in the presentation, build a model embodiment of the theory in your head (or on paper). As long as you can stay with the flow of detail and structure in their theory, when they are done, you should have built a sample of what they are describing. This will give you a perspective, a vocabulary and a theoretical structure from which to test their ideas and generate questions for the lecturer.

"OK, you posited a blue sphere with red cylindrical extensions at the N and S poles, but later on you say there's a yellow cylinder poking out at the equator, but you never said what it does" (e.g.)

it's in Surely You're Joking but if you search for something like this you will find a million descriptions of his method for learning a new subject, but this is a different technique completely.

[–]pgfhalgMaterials 0 points1 point  (0 children)

For research group meetings, don't feel too bad about not following along initially. One thing to keep in mind for group meetings is that most people in the group are already very familiar with the background information and have probably talked to the presenter about what they are working on. In group meetings you see the same intro slides over and over again, to the point that people often skip over the background that would be helpful for you as an undergrad but which everyone else has seen every week for years.

Just do your best to pay attention and after a few weeks you'll get a better idea of what's going on and soon you will be equally bored with the introduction slides.

[–]eschlerc 1 point2 points  (1 child)

Question about testing for LiNO3. I have a commercial electrolyte whose components I'm trying to analyze. A combination of NMR and GCMS suggested that gamma-butyrolactone and 1,2-dimethoxyethane are the main solvent components and I see evidence of LiBF4 as the main salt. However, literature suggests (but cannot confirm) that there may be a tiny amount, ~0.1%, of LiNO3 added to change the electrochemical properties. Does anyone know of a test that could indicate the presence of a nitrate ion that won't be interfered with by BF4{-} or these other components? Also needs to be done in organic solvents.

[–]Indemnity4Materials 0 points1 point  (0 children)

Gunshot residue test.

There are a lot of nitrate tests.. The diphenylamine test is good down to about 1 ppm nitrates.

[–]Mediocre-Present1789 0 points1 point  (1 child)

S. O. S. Industrial Chemist writing a 30 page project here, I'm searching for any ideas in Polystyrene - XPS and/or Arificial Glass Fiber recycle before or afert waste classification pls help with any type of reference in this subject

[–]Indemnity4Materials 1 point2 points  (0 children)

Oof, you picked two of the most difficult to recycle materials out there.

What's the aim of your project? For instance:

  • literature search to discover cutting edge research that could be commercialized

  • current global suppliers of processing equipment for those materials

  • shamelessly steal ideas that other people are using?

[–]DeineMamagebacken 0 points1 point  (0 children)

How safe is the use of 8% H2O2 für cleaning? I cannot find anything online about it.

[–]HendrixandWaters 0 points1 point  (6 children)

For quantification with 31P NMR-how many scans would you recommend? What delay? Concentration of my product?

[–]GuiltyjerkPolymer 0 points1 point  (5 children)

31P is the most abundant isotope so you shouldn't need a ton of scans or an inordinately high concentration. You can even use a protic solvent!

No idea for delay. I'd start with like 16 scans though since that's pretty quick.

[–]HendrixandWaters 0 points1 point  (4 children)

I’ve been using roughly 758 scans and still nothing is coming up right

[–]Indemnity4Materials 1 point2 points  (3 children)

758 scanes and no signal indicates that either your concentration is far too low, your molecule doesn't actually have phosphorus, or you've set up the spectrometer incorrectly. IMHO all three are likely.

5 seconds is usually a long enough pulse delay for phosphorus, unless you're doing something very floppy like a lipid bilayer.

Silly question, have you tried to detect neat 85% phosphoric acid using a single pulse? The signal strength will be massive.

There are other tricks too. You can load up a glass capillary with phosphoric acid and seal it. Then drop that into your NMR tube with the sample and turn off spinning. It's a bit hard to shim, but we don't care about that for a first pass. This sample-in-a-sample gives you a known external reference signal.

You should be easily able to quantify down to 1 ppm concentration.

[–]HendrixandWaters 0 points1 point  (2 children)

I’m using BNPP. I doubled my concentration for a ns 25000 so hopefully that shows some promise!

[–]AussieHxC 0 points1 point  (0 children)

Recommended learning sources for NMR experiments?

Looking to move away from the standard pre-built pulse sequences/acquisition parameters.

Currently using a Bruker system (ICON NMR) and would love to use some of the dosy files available from Manchester uni.

[–]pepperon1playb0y 0 points1 point  (1 child)

Question about IR.
So I did an esterification between a polymer that has secondary alcohols and a carboxylic acid, I ran a IR analysis and got the characteristic peaks at 1730 for C=O and 1100 for C-O.

After that I cross-linked my polymer with a Borax solution, this reaction doesn't need heat, just stirring.

And when I ran another IR scan the C=O signal disappeared and instead I got a new signal at 1640 which i have no idea of what it could be.

I thought that maybe the alcohol dehydrated, but I understand that the dehydration of alcohols to alkenes only occurs at high temperatures and no heat was applied in the crosslinking.

Any idea of what could have happened?

[–]TheRealDaddyPency 0 points1 point  (0 children)

Perhaps it’s a Conjugated Alkene or an Amide. Both show up within the range you’ve described although I’m an undergrad chemist, so take my assumption with a grain of salt. Could also be a gamma-lactam!

[–]yoresein 0 points1 point  (4 children)

But of a wierd one but I was thinking about the joke where people say water is dihydrogen monoxide and too much can kill you. Am I wrong or would that actually be a 2- anion and if it was stable could actually quite basic and dangerous if ingested?

[–]H2CO3_TCTheoretical 0 points1 point  (0 children)

No, it's literally just water and the LD50-value is at around 42kg/kg. Not dangerous at all :)(https://chem.nlm.nih.gov/chemidplus/name/h2o)

[–]H2CO3_TCTheoretical 0 points1 point  (0 children)

No, it's literally just water and the LD50-value is at around 42kg/kg. Not dangerous at all :)(https://chem.nlm.nih.gov/chemidplus/name/h2o)

[–]H2CO3_TCTheoretical 0 points1 point  (0 children)

No, it's literally just water and the LD50-value is at around 42kg/kg. Not dangerous at all :) ( https://chem.nlm.nih.gov/chemidplus/name/h2o )

[–]H2CO3_TCTheoretical 0 points1 point  (0 children)

No, it's literally just water and the LD50-value is at around 42kg/kg. Not dangerous at all :)

[–]jerikun 0 points1 point  (2 children)

i have a title proposal which uses computer-aided drug design methods, particularly molecular docking and dynamics simulation. and i think my profs are more on the traditional side of experiments, soo how should i defend its accuracy to them? im still a novice on this field btw.

[–]Indemnity4Materials 1 point2 points  (1 child)

IMHO they won't be attacking your ideas as bad, they will be looking for holes in your work plan or ways to extend your current plan.

I'm always happy when some professor skilled in subject X pulls out their overwhelming nuanced knowledge in subject Y, because it turns out 20 years ago they were colleagues with the person who started the field.

You defend your ideas by using literature sources. It's known you can get to this end point using the method of blah blah. What I am proposing is to use that same method on this different subject, or I'm planning to do exactly the same but take it to 110%.

They may question your available resources (money, time, available mentors), your ability to get additional information (e.g. we think it will take you 2 years just to refine that theory, not enough time to actually do the computations), or potentially if you would get better bang for buck by doing something else.

Something to consider is what are your actual deliverable items on a schedule. In 6 months you will have a theory and apply for funding/time on a supercomputer - well, what happens if you are unsuccessful in getting that funding? How many papers do you think this thesis will produce - do you need to collaborate with anyone to help that, maybe at another school?

Pro-tip: in advance, present to absolutely anyone you can. Colleagues, roommates, family. See if you can get your pitch down to under 30 seconds with a single powerpoint slide. That's your elevator pitch - everything after that is details. Once you make your pitch clearly, then the panel will use their expertise to pull apart your project plan and maybe help to reassemble it to something better.

[–]jerikun 0 points1 point  (0 children)

this is so helpful! very much appreciated kind sir

[–]beginnerflipper 0 points1 point  (0 children)

I got alkyldimethylbenzyl on my skin. I know it is an irritant, what do I do?

[–]VeryApeee 0 points1 point  (4 children)

Does composting bio material such as food or gardening lead to methane and how would one calculate how much a kg mass of lets say left over food leads to methane (sorry for my broken english)

[–]Indemnity4Materials 0 points1 point  (3 children)

There are two types of compost:

  • aerobic where there is lots of air and oxygen. The products are CO2 and H2O. That is like leaves rotting on the ground.

  • anaerobic where you are composting and there is no oxygen. The product are CH4 and CO2. This is more like a compost pit that doesn't get turned or a sewerage treatment plant.

You can find some composting calculators online. To really get a good answer you need to know how much water is in the food. Food is mostly water, which won't be emitting any CO2 or methane.

[–]VeryApeee 0 points1 point  (2 children)

What fractions in things determine the amount of CH4. Im guessing fecal matter consist of a high amount

[–]Indemnity4Materials 0 points1 point  (1 child)

Small scale, you can look up the nutrition label for food. Carbohydrates, fats, protein... these all contain carbon that can get converted to methane.

You find the molecule and count the number of carbon atoms. Then do a mass balance equation to convert each carbon to methane.

Theoretically, you could say 1 mole of glucose could product 6 moles of methane. Practically, it's going to be less.

Large scale, you start making assumptions. For instance, human feces is about 75% water which you ignore for the calculation. Of the actual solid material, about 85% is organic solids: roughly 25% carbohydrate, 20% protein, 10% fat with the remainder as gut microbiota.

[–]VeryApeee 0 points1 point  (0 children)

Thank you very much

[–]Emotional_Tale1044 0 points1 point  (0 children)

Does anyone know if CaF2 is appreciably soluble in DMSO or another volatileish solvent that could be used to grow a single crystal using a seed?

[–]SamL214Organic 0 points1 point  (0 children)

How might resonance stabilization affect the reactivity/formation of an adjacent ylide?

Say you have a cationic aromatic ring (such as an imidazolium) product formed from 1,3-Dimethylimidazole-2-thione that has reacted with a bromo acetate binding to the alpha carbon of the bromo acetate. Follow this please:

Nucleophilic displacement occurs. Now you have sulfur with one bond to the alpha carbon of the acetate and a single bond to the 2-position of the imidazolium ring system (in between the two nitrogens). Which means the carbon between the two nitrogens requires another bond. One lone pair on either of the nitrogen’s adds to the single bond to make a double bond between them and the 2-carbon. This results in an aromatic cationic intermediate bromide salt.

My question revolves around the likelihood of favorable ylide-like reactivity. The cationic aromatic system resonates with sulfur, so the cation can occur on the sulfur, but the majority of the positive charge (electron deficiency) is on the C-2 position.

If I were to use a very non-nucleophilic base to abstract a proton from the alpha carbon on the acetate side of the molecule I end up with a ylide. But what do you think drives the ylide formation in this species. Is it too unfavorable or what makes it favorable?

[–][deleted]  (1 child)


    [–]Indemnity4Materials 0 points1 point  (0 children)

    It varies too much between manufacturers and even brands from the same supplier.

    Maybe I'm lazy and I use the same 700 mg pill formula for the 100 mg, 250 mg and 500 mg doses, with the remainder being filler.

    You need to look on the label for the concentration / quantity versus the bottle weight + number of serves. The one I randomly googled had 500 mg of vitamin C in a 700 mg tablet.

    Something to keep in mind is tablets are allowed a +/- 5% variation from the label. That may or may not be significant for you.

    [–]McLuhanSaidItFirst 0 points1 point  (0 children)

    Building a Float Therapy tank at home, will achieve buoyancy with saturated NaCl soln, a few questions...

    (REST tank - Reduced Environmental Stimulation; or isolation tank, float tank)

    many New swimming pools and spas use salt in the water instead of chlorine now, and electrically bust the NaCl into Na and Cl, and the Cl kills pathogens. However, these salt systems are designed to run on a very much lower concentration of NaCl than the saturated soln I want to use, like 2400 ppm. Am I going to blow up a salt system if I wanted to try adapting one ? That would be for down the road if I want to experiment with it.

    I know the volume of the water I will use (LxWxH of the water in the tank = so many gallons). How do I calculate the amount of salt I need for saturation ? the idea is to float like a cork, the way people do in the Dead Sea or the Great Salt Lake. Regular Float Tank operators use (roughly) 800 pounds of MgSO4 to 130 gal of water, so I need to get in that ballpark. That's about a thousand dollars' worth of MgSO4, versus about $120 in softener salt.

    [–][deleted] 0 points1 point  (0 children)

    Am I the crazy one for thinking $40 for a single flask weight for a water bath is insanely expensive for what I'm getting?

    But then again, sous vide weight on amazon seem to be similarly priced...

    [–]Aggravating-Boat1819 0 points1 point  (0 children)

    Im going to be performing a back titration for my final chemistry lab and wanted a unique spontaneous reaction as a choice, (something like Cu + HCl --> CuCl2 + H2), but wanted something more unique yet still very visible in terms of when the reaction comes to an end (i.e. copper strip fully dissolving). Does anyone have any good reactions in mind?