When using sunscreen, can our body produce Vitamin D? | AskScience Blog

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When using sunscreen, can our body produce Vitamin D?

When using sunscreen, can our body produce Vitamin D?


When using sunscreen, can our body produce Vitamin D?

Posted: 26 Jan 2019 08:55 PM PST

Given that Hawking radiation intensity increases exponentially as the mass of a black hole decreases, how does a black hole "gradually" form out of normal matter collapsing?

Posted: 26 Jan 2019 11:00 PM PST

If a neutron star, or equivalent, is collapsing as it has enough mass to overcome the strong nuclear interaction, how would it become a black hole? As soon as some matter from the core collapses within the Schwarzchild radius, wouldn't it evaporate extremely quickly (or explode) due to massive Hawking radiation? For example this calculator (http://xaonon.dyndns.org/hawking/) suggests that the first 1 micro-gram of the black hole will evaporate in less than 1 unit of Plank time. Does the rest of the collapsing matter need to supply the micro black hole with more matter/energy than is lost due the radiation? Is it even relativistically possible for it to collapse fast enough to do that? Even if so, would it be possible for it to fail (due to angular velocity for example), and if it fails would the neutron star potentially blow up instead of collapsing?

submitted by /u/adamantismo
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why DM type 2 affect kidneys and eyes more than other organs and cause diabetic retinopathy , nephropathy?

Posted: 27 Jan 2019 06:30 AM PST

Why is urine a steady stream but semen is released in pumps?

Posted: 26 Jan 2019 07:07 PM PST

What causes the opposite effects of size<-->speed in gel-electrophoresis and size exclusion chromatography?

Posted: 27 Jan 2019 06:52 AM PST

So i tried answering this with a google search but i didn't really find an answer that compares the two methods in regards to the aspect i'm confused by:

So as far as i understand it, both separation methods use a porous gel to separate molecules by their size.

The explanation for the SEC that i found is, that larger molecules cannot fit into as many pores so they barely interact with the gel and pass through it faster through the paths that they can fit through. (So basically there are less "useless detours" that lead in a direction lateral to the traveling direction/ spread out the molecules and increase its interaction with the gel)

The explanation for the gel electrophoresis says, that the larger molecules will have problems traversing through the pores because they won't fit through most of them so it takes them considerably longer to find random paths through the gel. (So there are also fewer "good" paths that allow large molecules to pass through the gel in the intended travelling direction)

Both explanations sounded intuitive until i read them at the same time. Why does the effect that slows down larger molecules during electrophoresis not also affect them during SEC and vice-versa (why don't they pass faster during gel electrophoresis).

I think my problem/misunderstanding is kinda linked to understanding the key difference between what they refer to as "interparticle volume" and the "pores" in the SEC. In the end it sounds to me like you have a gel/solid with tiny "tunnels" inside of them through which the molecules can traverse. Why does it matter if these tunnels are

A) part of the small gel-beads/porous particles themselves

or

B)Between individual beads/porous particles

Also i'm a little bit confused by how some explanations use the word "interaction". Because some of them use it as chemical/electrical interaction and say that "the analyte must not interact with the stationary phase" in the SEC so there is a separation solely by size yet sometimes "interaction" was used in a way that to me sounded more like its ability to diffuse and spread out into the pores.

Thanks in advance for any input that might help understand these processes a little more and have a nice day.

submitted by /u/Madpenguin_CH
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If earth's gravity lessens depending on how far you get from the surface of earth, even though its not by much, would that mean that the closer you get to the core the greater the force of gravity? If so, would that mean it would be theoretically possible to do some Goku/Vegeta gravity training?

Posted: 26 Jan 2019 08:16 PM PST

How much do children's foreign language shows like Dora The Explorer actually help a viewer learn another language?

Posted: 27 Jan 2019 05:24 AM PST

Do the senses of smell, taste, and touch fade with time like hearing and sight?

Posted: 27 Jan 2019 04:50 AM PST

Are monoclonal antibodies more effective than small molecule drugs?

Posted: 27 Jan 2019 04:10 AM PST

Why or why not?

submitted by /u/MattyMattsReddit
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Instead of making a particle accelerator longer, why don't we make the particle go around it more?

Posted: 26 Jan 2019 08:36 PM PST

Since length is a limiting factor in the amount of energy that can be given to a particle, why can't we send a particle around the LHC until it has enough energy to test what we want?

submitted by /u/eggAMA
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What do we know about mating in non-avian dinosaurs?

Posted: 27 Jan 2019 04:05 AM PST

What do we know about non-avian dinosaurs and mating? Do we have fossils of mating dinosaurs? And especially how did sauropods mate and do we see traces on the bones?

submitted by /u/Fancy_lamp
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Is the DNA bomb from Call of Duty theoretically possible?

Posted: 27 Jan 2019 12:10 AM PST

Is it theoretically possible to create a bomb or even a pathological agent that targets a specific race of individuals but completely leaves alone anyone else? Are there real life examples of diseases that only affects certain group of communities but is completely harmless in others?

submitted by /u/dEVoRaTriX
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Why are noble gases so stable?

Posted: 26 Jan 2019 09:54 PM PST

I've been studying Chemical bonding and understand that most atoms tend to want to get a fully filled valence shell of electrons. What I don't understand is why. How does having a fully filled energy level/shell (even if we're just talking about the main group elements here) give you stability? Does it have to do with something with the Hund's rule and pairing of electron spins? Even if it does, why is it that Beryllium, which has a fully filled 2s orbital, and essentially doesn't even have any p electrons or p orbitals yet, not stable? What makes a fully filled p subshell/orbital so stable?

submitted by /u/RyukSkywalker
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Can kitchen knives with single-bevel designs really achieve stronger, sharper and thinner edges compared to knives with double-bevel designs?

Posted: 27 Jan 2019 03:44 AM PST

Note: I'm simplifying.

German and french knives are "flat ground" with a symmetrical double bevel edge, most japanese knives are "chisel ground" with a single bevel edge instead. Visual representation here.

Knife sellers claim that chisel ground knives can achieve sharper, thinner and stronger edges compared to flat ground knives and browsing forums that seems to be the general opinion.

Given the alloy used in the blade is constant, would you say the claim holds?

submitted by /u/Keyvanizator
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Will Saccharomyces Ferment increase the AhR activity of Pityrosporum Folliculitis?

Posted: 27 Jan 2019 03:26 AM PST

Galactomyces ferment has shown to increase the aryl hydrocarbon receptor (AhR) capacity of Pityrosporum folliculitis aka Malassezia Folliculitis. The afore yeast ferment is also a potent activator of AhR, as it induced the nuclear translocation of AhR and subsequent CYP1A1 upregulation.

However, does the same applies for Saccharomyces ferment and its respective filtrates and subjugated filtrates? Saccaromyces is a different but similar genus of fungi compared to Galactomyces. On the other hand, lactobacillus, bifidobacterium, lactococcus and various other lactic-acid producing bacteria is said to have no effect on the AhR capacity of Pityrosporum folliculitis.

submitted by /u/OrganicAsparagus2
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What happens to the Cochlear fluid of the astronauts?

Posted: 26 Jan 2019 08:55 AM PST

Thought about this last night, couldn't find an answer online. So what happens to Cochlear fluid in low-g environments? How do Astronauts not get violently sick all the time?

submitted by /u/Clownsheuz
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What is the maximum temperature you could raise waters boiling point to?

Posted: 26 Jan 2019 07:08 PM PST

Since waters boiling point depends on how much pressure it's under, what is the maximum boiling point water can be raised too?

submitted by /u/qowijibo
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How do you differentiate between the histology of pyelonephritis and coagulative necrosis of kidney?

Posted: 27 Jan 2019 01:55 AM PST

I always get confused between the histology of pyelonephritis of kidney and coagulative necrosis of kidney in the histology slide.

I realize that pyelonephritis is a form of liquefactive necrosis, but how can you differentiate between the two in the histology slide? They both look extremely similar and they both have neutrophil infiltrate.

submitted by /u/HouhoinKyoma
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Can Ammonia be used to substitute chloride ion ligands in aqueous copper(II) chloride in a ligand substitution?

Posted: 27 Jan 2019 01:35 AM PST

Title explain everything. I am planning to do a complexometric titration using EDTA to determine the amount of copper(II) ions in an aqueous solution, and was wondering if the above could happen since the pH of the solution must be alkaline for the titration to occur. Many thanks!

submitted by /u/mysteriousdude2761
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Since our immunity strengthens based on experience, would that mean that an E. Coli infection give you immunity to that certain strain of E. Coli in the future?

Posted: 27 Jan 2019 01:08 AM PST

How does popcorn 'pop'?

Posted: 26 Jan 2019 02:17 PM PST

How do pulsed neutron sources work and when are they utilized?

Posted: 26 Jan 2019 02:54 PM PST

I know that the pulsed sources have been used in particle accelerators, but don't most of them use proton beams?

submitted by /u/gracer_5
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