I am simply on a quest to find an effective non-distillation method for purifying isopropyl alcohol used for rinsing resin 3D prints.

I have seen some elaborate systems for curing and then filtering resin that is suspended in the isopropyl by running it through standard carbon water filters. That just seems a bit over-complex and does a poor job of removing dyes. In some cases, the filters are not fine enough and the isopropyl will eventually get "sticky".

It seems to me that a finer filtration system would work much better. Carbon and celite should catch most of the monomers and oligomers, but I am not sure about the photoinitiators and other additives.

Distillation is obviously the best method for purity, but there may be a worse cleanup and a higher fire hazard risk.

Are there better materials that I could use for filtering besides celite and carbon? IPA is tiny compared to the rest of the molecules I am dealing with so filtration seems viable.

(I should note that I would bulk develop the used IPA in clear plastic containers in the sun for a day or two first.)

I'm referring to the human race evolving in the African continent and then migrating to the rest of the world.

Evolving in Europe made people light skinned to account for the reduction in sunlight exposure, are there any other traits which other ethnicities developed to adapt to their new environment? Or are the diifferent traits in different ethnicities just stuff that developed by chance and got somehow reinforced because of the isolation between populations?

This question came to my mind first thinking about "Asian eyes", do they serve any "purpose"?

There are many other bee species that can sting Humans and survive, but the European honeybee has a barbed stinger, so it cannot remove the stinger once it's stung. In attempting to remove the stinger the bee will rupture its lower abdomen and then die.

Why? What is the evolutionary advantage to that?

We often talk about the climate impact based on greenhouse gases, but extracting fuel from the ground and using it in exothermal processes of course also releases energy as heat.

This is mostly¹ in contrast with renewables, which make use of energy that's not long-term contained to begin with, so would end up as heat in our atmosphere anyways.

So, my question is: Does the amount of energy released by non-renewables have any notable impact on our global temperature? Or would it easily radiate into space, if we solved the greenhouse gas problem?

¹) In the case of solar, putting up black surfaces does mean that less sunlight gets reflected, so more heat ultimately gets trapped in our atmosphere. There's probably other such cases, too.

Say a dissolvable spring is compressed with a bolt and nut that do not melt in a sulfuric acid solution. The spring has quite a bit of potential energy at this point since it is compressed. Assuming the spring dissolves perfectly (no breakage, just complete disintegration), what happens to the potential energy of the spring?

Famously, Oppenheimer and co worked out how close a nuclear bomb test would be to causing a chain reaction of nitrogen fusion in the atmosphere. They made a lot of worst-case-scenario assumptions and still came to the conclusion that no, a nuclear bomb test wouldn’t scour the surface of the world.

But let’s say the atmosphere was twice as dense as it is. Or ten times as dense. At what point would that calculation turn very, very scary?

Obligatory xkcd

Edit: man, seriously, most of the people ‘answering’ this question didn’t even read it.

Okay, so I know this might be a bit hyperspecific, but I don't know where else to ask it. I'm working through a microbiology lecture, and the professor says the the B strain of E. coli has a tRNA suppressor that allows it to transcribe phage genes that have any nonsense mutation. That seemed a bit vague, so I decided to look it up. But the only thing I can find that's even remotely similar is that that strain doesn't express T7 RNA polymerase, which doesn't seem terribly helpful. Is there anything like this in that particular strain? It seems like a load of bs to me that a bacterium should just be able to ignore any stop codon.

Edit: My prof might have been referring specifically to an amber mutation. So, just one stop codon. Seems my resources are just poorly worded.

Asking because while I see that paint hardeners exist in the USA, there doesn't seem to be anything similar in my country (Brazil)

What could I use as a substitute to harden paints? Are there any catalysts or powders that would work?

Google and DDG always show sites/articles about epoxy resins whenever I search for "acrylic hardener", is it safe to assume that catalysts for epoxy, like polyamide, will work with acrylics?

Now that late spring/early summer is upon us, there's increasingly more headlines about less rain in various places (recent floods notwithstanding). I'm assuming that's because water is evaporating and not returning to those places, but where is it going?

Is it arriving, now, in these bursty flash floods? Is it staying longer in the atmosphere and moving to new locations? Is more of it just staying in the atmosphere period?

I assume it would break into smaller particles similar to the formation of microplastics. I hear about the effects of microplastics all the time. Are the effects of disposed rubber on the environment studied as extensively?

I know evolution is governed by chance and it is random but does it make sense to "ruin" sleep if there's light? I mean normally, outside, you never have pure darkness, there are the moon and stars even at night. In certain zones of the Earth we also have long periods of no sunshine and long periods of only sunshine.

I don't know if my question is clear enough but I hope so.

Bonus question: are animals subject to the same contribution of light or lack of it to the quality of sleep?

Is it a stable/static effect no matter what, or is it a bit more stretchy/bouncy depending on how the object is behaving?

Thank you!

Say I am sitting in the shadow, but the sunlight gets reflected by some window pane onto me. Does this contain enough UV light to give me a sunburn?

If sociology's exclusive to humans, then what might be the field of other social animal research?

They say it's a picture of atoms, but what are the atoms: the glowing yellow balls or the entire meatball including the darker red? If it's the meatballs, then why do some have apparently two nuclei?

Here's the public press release: https://news.cornell.edu/stories/2021/05/cornell-researchers-see-atoms-record-resolution

Here's the actual scientific article: https://www.science.org/doi/10.1126/science.abg2533

So, let’s say there’s a species of bacteria that is known to dwell in Greek yogurt. How long would it take before that species of yogurt-dweller only has modern descendants different enough to qualify as one or more new species?

I'm thinking of switching fields within STEM and there are some mathsy modules which I missed out on during my undergrad (biology) that would come in really handy right now.
Since I would like to avoid doing another bachelor's from scratch, I was hoping there might be a website that lets you pick and choose from a range of undergrad-level subjects that you would take online, and then possibly give you a certificate that you could put on your CV.
Does anyone know if something like this exists?