ultraviolet light


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Related to ultraviolet light: visible light, infrared light, Ultraviolet Rays

ultraviolet light

The segment of the electromagnetic spectrum between 200 and 400 nm, including photons emitted during electronic transition states. UV-C (200–290 nm) is damaging to DNA and amino acids, but is blocked in the stratospheric ozone layer; UV-B (290–320 nm) is partially blocked by the ozone layer; UV-A (320–400 nm) is the least dangerous, but may still be hazardous with photosensitising medications (e.g., tetracyclines, thiazides), and in patients with lupus erythematosus and light sensitivity disorders (e.g., porphyria). UV-A suppresses delayed cutaneous hypersensitivity, causes photoageing and reduces serum carotenoids; the accelerating depletion of the stratospheric ozone is implicated in the increased incidence of cataract, and melanomas.

UV light may also damage the less sensitive purines, causing spontaneous depurination, leaving a “naked” deoxyribose residue in the DNA (apurinic sites). Repair of UV-light-induced DNA damage is defective in chromosomal breakage syndromes (e.g., xeroderma pigmentosa and Bloom syndrome). The mutational effect of UV light is not due to direct DNA damage, but rather occurs during the error-prone process of DNA repair.

ultraviolet light

Ultraviolet radiation Physics The part of the invisible electromagnetic spectrum below violet, including photons emitted during electronic transition states Wavelength 100-400 nm Public health The electromagnetic spectrum between 200 nm and 400 nm which is emitted by the sun. See SPF, Sunscreen.
UV light types
UV-A Long wave, 'near' UV, black light; short wave UV-A–320–340 nm; long wave UV-A–340–400 nm; no UV-A absorbed by ozone layer
UV-B Middle UV, sunburn radiation UV-B–290–320 nm; most UV-B is absorbed by ozone layer
UV-C Short wave, far UV, germicidal radiation, ≤ 290 nm; absorbed by ozone layer; has no role in photobiology of natural sunlight

ultraviolet light

Electromagnetic radiation of shorter wavelengths than visible light but longer wavelength than X-rays. Ultraviolet light is divided into three zones—UVA with wavelengths from 380 to 320 nanometres (billionth of a metre), UVB from 320 nm down to 290 nm and UVC from 290 nm down to one tenth of a nanometre. UVC and most of UVB are absorbed by the ozone layer in the earth's stratosphere. Ultraviolet light causes sunburning and damages the skin's elastic protein, collagen. It is also a major factor in the development of the skin cancers rodent ulcer (BASAL CELL CARCINOMA), MALIGNANT MELANOMA and SQUAMOUS CELL CARCINOMA. It causes PINGUECULA and PTERYGIUM in the eyes.

ultraviolet light or ultraviolet radiation (UV)

a type of electromagnetic radiation beyond the wavelength of visible violet light, ranging from 18,000 to 33,000 nm (see ELECTROMAGNETIC SPECTRUM). UV light is not an ionizing radiation like X-RAYS and can only penetrate a few cells. However, it is used as a powerful MUTAGEN of microorganisms to cause the formation of thymine DIMERS in DNA, and can be harmful to the human RETINA. Some organisms can detect UV light (see ENTOMOPHILY). UV is a common cause of skin cancers; see MELANOMA.

Ultraviolet (UV) light

A portion of the light spectrum not visible to the eye. Two bands of the UV spectrum, UVA and UVB, are used to treat psoriasis and other skin diseases.

ultraviolet light

; UV light light energy (from part of electromagnetic spectrum) of shorter wavelength than visible light

ultraviolet light,

n light beyond the range of human vision, at the short end of the spectrum. It occurs naturally in sunlight; it burns and tans the skin and converts precursors in the skin to vitamin D. It is used in the treatment of psoriasis and other skin conditions. Prolonged or excessive exposure to ultraviolet light can damage the skin and increase the susceptibility of the skin to cancer.

Patient discussion about ultraviolet light

Q. what does a sun block cream do? and what are a UV rays?

A. It blocks out harmful Ultra violet rays from the skin as the previous entries have related; however it can also block your ability to produce vitamin D. If you live in a northerly area or one that receives limited sunlight, its recommended to get at least 15 minutes of sun a day (this is probably best done with minimal sunblock) and according to personnal sun sensitivity. Another thing to keep in mind is that sunblock works best if applied 20 minutes before sun exposure.

More discussions about ultraviolet light
References in periodicals archive ?
She noted that dermatologists now use ultraviolet light to treat some skin diseases, administering it to patients inside a chamber under controlled circumstances to avoid burning.
When the scientists exposed the vesicles to ultraviolet light, the membranes glowed.
The process involves drawing a small sample of blood, exposing it to ultraviolet light to inactivate pathogens, then returning the blood to the patient as an auto-transfusion - all in a closed system.
In 1997, Gilchrest and her colleagues reported that pTT also prompts cells to quicken their repairs of DNA damage caused by ultraviolet light.
The study's conclusion was that BioAstin significantly increased the amount of ultraviolet light energy required to produce skin reddening following daily ingestion of BioAstin for two weeks.
Researchers had already observed that ions in the outer part of disks absorb some of the ultraviolet light.
However, Cerus studies showed a drop of 10 to 20 percent drop in platelet concentrations in blood treated with psoralens and ultraviolet light.
The potential of BioAstin to retard and prevent sunburn by ultraviolet light is highly significant," said Gerald R.
The lack of information from ultraviolet light made studying galaxies in the HUDF like trying to understand the history of families without knowing about the grade-school children," said principal investigator Harry Teplitz of Caltech in Pasadena, California.
With its vibrating base plate Bed Vac starts by loose, then zaps them with ultraviolet light killing them to feed.
Scientists have created cats that glow bright red when they are placed under ultraviolet light, a type of light that can't be seen by humans.
According to a report in the Telegraph, scientists have now found a way to paralyze tiny worms when they expose them to ultraviolet light.

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