Recent comments in /f/askscience

viridiformica t1_j9tg13o wrote

Reply to comment by Whako4 in Why is urine yellow? by nateblackmt

In part because 'brown' is a huge range of colours. Everything from dark red to dark green will be called 'brown' if it isn't highly colour saturated. Just about the only colour that won't be is blue, which is a fairly rare pigment in nature

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djublonskopf t1_j9tbhh0 wrote

Reply to After a surgery, what happens to the air that was inside the incision? by cimmic

It is absorbed by the body cavity lining, makes its way into the blood stream, and is exhaled. The absorption happens pretty much exactly the way it happens in your lungs (diffusion), there's just less surface area to work with than in the highly-branched lung interior, so it takes a bit longer.

O2 and CO2 are absorbed pretty quickly into the blood compared to the nitrogen gas (N2) that makes up the majority of air. So when laproscopic surgeons insuflate a surgical area with gas to give them a little more room to see and work, they intentionally use CO2...which helps any gas left behind after the surgery to be absorbed more quickly, and also protects the patient in case a (small) bubble got into the bloodstream (as a bubble of pure CO2 will be absorbed into the blood faster and thus might do less damage than a longer-lasting nitrogen bubble.) But even a regular air mix at an incision site will be absorbed before too long.

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EmilyU1F984 t1_j9t8zcs wrote

Reply to Why is urine yellow? by nateblackmt

It’s relevant but not the whole explanation, also all organic molecules get their colour from those conjugated double bonds, whether they are blue yellow or red doesn‘t matter.

It‘s just that yellow requires the lowest amount of bonds, so any break down products are likely have enough bonds to go from only absorbs UV to also absorbs blue.

In urine the natural healthy colour is made from the molecule that oxygen is transported around in your body.

It’s gets broken down to smaller bits, shorter conjugated electron systems hence yellowish colour.

Additionally: the way our body metabolizes random molecules, like pigments in plant food etc, is by oxidizing them into more water solubles derivatives.

This oxidation is usually pretty efficient at double bonds (which make conjugated systems) And if your body breaks the double bond in the middle of a conjugated system, you usually end up with something that doesn’t have a large enough conjugated system to even absorb blue. So it appears colorless.

Take the imine in your example: break that, and you end up with just a benzene ring, which is colorless.

That‘s why foods and other colorful substances rarely dye the urine.

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Unlikely_Plankton_11 t1_j9t6tug wrote

Reply to comment by veerKg_CSS_Geologist in What will be the environmental impact of de-orbiting 42,000 Starlink satellites every five years? (Explanation in post) by OvidPerl

It’s a relevant point to make, because we still have barely started to fix the actual massive problems and people are already bored and looking for distractions in the noise.

Of the two things, coal plants are so hilariously worse and larger in scale that satellites may as well not exist at all for all the difference it makes. When you have people going “yeah yeah coal whatever, let’s look into these satellites though!” it takes up mind space, airtime, political capital, and manpower that could be used on far more impactful things.

And in this case it sure seems like the motive is “ugh corporations,” not genuine concern for the environment.

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Shadowwynd t1_j9t68zj wrote

Reply to comment by grandtheftbonsai in Do all thinking creatures on Earth use neurons? Does an example of non-neuron based biological "intelligence" exist? by Wun_Weg_Wun_Dar__Wun

Slime molds can also solve advanced mazes. I would posit this is intelligent behavior - problem solving - without neurons. https://youtube.com/watch?v=7YWbY7kWesI&feature=share

There is also the researcher who built a roller coaster for her mimosa plants - the first few times the plants freaked out and closed up, then they realized “no biggie” and were fine with it - at some level they learned and remembered without neurons. https://dustandtribe.com/2020/11/09/pavlovian-plants/

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