Questions tagged [uv]

Non-visible light with a higher energy and shorter wavelength than violet light, UV is notable for its ability to cause DNA damage.

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Could life protect itself from ultraviolet radiation? [closed]

I have heard it argued that life as we know it (DNA-, RNA- and protein-based) could not have evolved without the ozone layer to protect it from UV radiations. It seems to me that mechanisms to deal ...
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Spectroscopic methods for quantifying peptides/proteins with or without Tryptophan or Tyrosine content

I have several peptides (20-50 amino acids long) which I want to quantify the solubility/concentration in a solvent at certain temperature and pH. These peptides may or may not contain Tryptophan or ...
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Why does UV radiation from the Sun cause skin cancer?

What is the specific mechanism makes non-ionizing UVA and UVB radiation carcinogenic? Can lower energy light, like visible light, be carcinogenic because of this mechanism, or is there some kind of ...
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Estimate mutation rate in UVC treated cells

I am wondering how to get a coarse estimate of the number of mutation I obtain doing UVC treatment on eukaryotic cells (microalgae) starting from information such as the survival rate, genome size, ...
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How can the layperson test whether a UVC light sold as "germicidal" is a fake or probably the correct wavelength?

Are there simple ways to test whether a light is likely short wave / UV-C, or at least whether it is probably a fake? Real Example: 2 lights are allegedly germicidal and supposedly emit germicidal ...
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Which is more efficient as a germicide: UVC, Ozone or combination and why?

I've read many contradictory info about ozone vs UVC light irradiation and cannot come to a conclusion, I am totally confused. As it commonly known UV germicidal irradiation is very effective against ...
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How far can free radicals from UV radiation diffuse through the skin?

UV radiation damages DNA through two separate mechanisms. Direct damage occurs when a photon is absorbed by DNA. Indirect damage occurs when a photon is absorbed by a chromophore, and the excited ...
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Calculating approximate dose of UVs received by a virus

I am making a very approximate calculation to determine the dose of UVs received by a virus standing at 1.5 cm from a UV source during a certain amount of time. Please let me know if my train of ...
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What is the simplest way to demonstrate the germicidal property of UV light?

This is intended for a high school project. I am familiar with the one that studies growth of e coli over time in a petri dish but I a bit concerned about as to how safe a demonstration of this nature ...
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14 votes
2 answers
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Can UV radiation be safe for the skin?

It is well known that UV radiation can damage the DNA and generally harm our skin. We also know that UV radiation helps on the production of melanin and Vitamin D. From what I could find, the DNA ...
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What part of the skin is damaged under sun exposure?

How exactly does extensive sun exposure lead to skin damage and increase cancer risk. In which part of the skin is the sun doing the most damage. Is it in the epidermis or beneath ? I would like to ...
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Could being exposed to excess UV in the arctic lead to a human eye color change? If so, what is the mechanism?

The CBS News article Expedition Antarctica: A father and son's journey to save the planet says (in part): Thirty-two years ago, Robert Swan made history as the first person to walk to both poles. ...
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UV-lamp, DNA and RNA extraction lab

I'm equipping a lab room (~3x5 meters) that's supposed to be used for DNA and RNA extractions. I know about the basic safety precautions when working with RNA and DNA extraction (fresh gloves, ...
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Why does UVA penetrate deeper than UVB, though it's weaker?

Even though UVA radiation ranges in longer wavelengths (315–400 nm) than UVB (280–315 nm) and thus is less energetic, UVA is able to penetrate deeper into the skin and even reach the dermis. Why is ...
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If my sunglasses provide "100% UVA/UVB Protection" why can't look directly at the sun?

Is it simply the amount of visible light entering the eye? I'm simply confused as to why experts say that sunglasses do not provide adequate protection when they are advertised as blocking 100% of the ...
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Why do redheads tend to sunburn more easily?

Reading Marion Roach's book on redheads she mentions visiting Rees lab where he shines UV light on her skin. Apparently this is an ongoing experiment of his regarding the propensity of redheads to ...
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Using UV to kill bacteria in shoes

I see that UV-C is the best to kill bacteria generally. We are interested in using to kill off odor in shoes. What illuminance is needed to kill most bacteria with UV-C? Thanks!
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How does UV light damage the DNA when the chromosomes are deep inside the cell?

When UV light falls on the skin it has to go through the cell membrane and the nuclear membrane to reach the chromosomes. So it looks like that the DNA is protected but it probably isn't. Won't ...
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Influence of artificial sunlight on the human body

In a hypothetical scenario, where a large, permanently manned craft is in a continual orbit, and natural sunlight cannot be used as the craft may keep moving and turning, artificial sunlight is used ...
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1 answer
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Is it safe to look indirectly at the Sun?

I.e., is exposure of sunlight onto the peripheral vision less damaging than exposure onto the fovea?
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2 votes
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Will an 11W UVC lamp kill bacteria?

If I shone a UVC lamp (11W) on something (say for example a plastic phone case) for an hour, would that kill off a noticeable amount of bacteria? That is, if I were to go over the case with a cotton ...
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Does every wave length of UV kill bacteria?

Will every wave length of UV work for killing bacteria? So will UV A, UV B and UV C all work? Or will only the shortest of the three, UV C, work? Also, will the average UV lamp help against bacterial ...
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How much time is required between repeated exposures to sun to prevent sunburn [closed]

After being in the sun, how much 'rest' is required before you can expose yourself again? e.g. from Wikipedia: Sunburn can occur in less than 15 minutes So if you were in a place where sunburn ...
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Detecting UV by humans

From my experience humans can detect UV - not by seeing it but by pain in their eyes. Many people (me too) feel pain when looking at UV lamps. When looking at sun through clouds I still can feel pain ...
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Are there specific conditions that allow humans to see ultraviolet wavelengths

It is fairly common knowledge that the lens in its normal state absorbs ultraviolet (UV) radiation. An interesting notion has come up from time to time in my reading that suggests there are a small ...
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