[permalink] [id link]
UV-B radiation can be harmful to the skin and is the main cause of sunburn ; excessive exposure can also cause genetic damage, resulting in problems such as skin cancer.
from
Wikipedia
Some Related Sentences
UV-B and radiation
The environmental consequence of this discovery was that, since stratospheric ozone absorbs most of the ultraviolet-B ( UV-B ) radiation reaching the surface of the planet, depletion of the ozone layer by CFCs would lead to an in increase in UV-B radiation at the surface, resulting in an increase in skin cancer and other impacts such as damage to crops and to marine phytoplankton.
UV radiation capable of penetrating nitrogen is divided into three categories, based on its wavelength ; these are referred to as UV-A ( 400 – 315 nm ), UV-B ( 315 – 280 nm ), and UV-C ( 280 – 100 nm ).
The ozone layer ( which absorbs from about 200 nm to 310 nm with a maximal absorption at about 250 nm ) is very effective at screening out UV-B ; for radiation with a wavelength of 290 nm, the intensity at the top of the atmosphere is 350 million times stronger than at the Earth's surface.
* Primary scientific data was collected in Punta Arenas, Chile, using a Brewer spectro-photometer, and " These results indicate that during the time when ozone depletion in the Antarctica takes place, an increase in UV-B radiation reaching the Earth surface affected the American continent at latitudes about parallel 50 ° S ."
This, coupled with the loss of dense body hair, caused early human skin to endure excess UV-B radiation and xeric stress.
In lush rainforests, however, where UV-B radiation and xeric stress were not in excess, light pigmentation would not have been nearly as detrimental.
Exposure to UV-B radiation causes an increased melanogenesis.
Ozone absorbs UV-B radiation, so its depletion allows more of this high energy radiation to reach the Earth's surface.
The exposure to UV-B radiation activates melanocytes to increase melanin production, which can cause freckles to become darker.
UV-C radiation spans from 0. 1μm to. 28μm, UV-B from 0. 28μm to 0. 315μm, UV-A from 0. 315μm to 0. 4μm, the visible spectrum from 0. 4μm to 0. 7μm, and NIR arguably from 0. 7μm to 5. 0μm, beyond which the infrared is thermal.
These factors include, decreased temperature, predatory cues and increased levels of UV-B radiation.
These declines are perceived as one of the most critical threats to global biodiversity, and several causes are believed to be involved, including disease, habitat destruction and modification, exploitation, pollution, pesticide use, introduced species, and increased ultraviolet-B radiation ( UV-B ).
The tanning process can also be created by artificial UV radiation, which can be delivered as UV-A, UV-B, or a combination of both.
In the second process, triggered primarily by UV-B, there is an increase in production of melanin ( melanogenesis ), which is the body's reaction to direct photodamage ( formation of pyrimidine dimers ) from UV radiation.
Ultraviolet B ( UV-B or UVB ) radiation is in the wavelength range 280 to 320 nm.
Exposure to UV-B radiation induces the accumulation of usnic acid and melanic compounds.
Ambient UV-B radiation causes deformities in amphibian embryos.
UV-B and can
The purpose of the melanogenesis is to protect the hypodermis, the layer under the skin, from the UV-B light that can damage it ( DNA photodamage ).
With the production of the melanin, the skin color darkens, but the UV-B in sunlight can also cause sunburn.
UV-B and be
Even if a small amount of UV-B were to be transmitted through the glass, it would be absorbed by the plastic layer.
However, in order to cause true melanogenesis-tanning by means of UV exposure, some direct DNA photodamage must first be produced, and this requires UV-B exposure ( as present in natural sunlight, or sunlamps that produce UV-B ).
UV-B and skin
The color of the melanin is dark and it absorbs all the UV-B light and it blocks it from passing the skin layer.
Thus, the effect of UV-A leads to skin darkening, but this is only cosmetic since it does not lead to greatly increased production of melanin and therefore also to little increase in protection against UV-B, or protection against sunburn.
Light therapy for skin conditions like psoriasis use UV-A ( 315 – 400 nm wavelength ) or UV-B ( 280 – 315 nm wavelength ) light waves.
UV-B and is
Singer trained as an atmospheric physicist and is known for his work in space research, atmospheric pollution, rocket and satellite technology, his questioning of the link between UV-B and melanoma rates, and that between CFCs and stratospheric ozone loss
It is present more uniformly throughout the day, and throughout the year, than UV-B.
It is blocked less than UV-B by many sunscreens, but is blocked to some degree by clothing.
Usnic acid is thought to play a role in protecting the photosymbiont by absorbing excess UV-B.
This is because UV-A, UV-B and visible lights are all capable of stimulating pigment production.
Parietin synthesis is enhanced by UV-B, and stimulated by photosynthates, such as those provided by the green algal Trebouxia symbiont.
UV-B and also
The ozone layer also blocks most, but not quite all, of the sunburn-producing UV-B ( 280 – 315 nm ) band, which lies in the wavelengths longer than UV-C.
UV-B and .
In several papers in the 1990s and 2000s he struck up other positions against the mainstream, questioning the link between UV-B and melanoma rates, and that between CFCs and stratospheric ozone loss.
In several papers in the 1990s and 2000s he questioned the link between UV-B and melanoma rates, and that between CFCs and stratospheric ozone loss.
UV-B energy levels at several altitudes.
Nevertheless, some UV-B, particularly at its longest wavelengths, reaches the surface.
The UVR8 protein detects UV-B light and mediates response to this DNA damaging wavelength.
Undoped quartz halogen lamps are used in some scientific, medical and dental instruments as a UV-B source.
radiation and can
A belowground basement can cut the fallout radiation to one-tenth of the outside level.
Ionizing radiation can cause the destruction of microorganisms and insects involved in food spoilage or, at lower doses, can inhibit their action.
Moderate radiation doses of from 100,000 to 200,000 rads can extend the shelf life ( at 35 F ) of fresh beef from 5 days to 5 or 6 weeks.
Ataxia can be induced as a result of severe acute radiation poisoning with an absorbed dose of more than 30 Grays.
Adaptive radiation, a characteristic example of cladogenesis, can be graphically illustrated as a " bush ", or clade, of coexisting species ( on the tree of life ).
Four features can be used to identify an adaptive radiation:
The binding of nuclear receptors by glucocorticoids, heat, radiation, nutrient deprivation, viral infection, hypoxia and increased intracellular calcium concentration, for example, by damage to the membrane, can all trigger the release of intracellular apoptotic signals by a damaged cell.
Defects in the cell cycle are thought to be responsible for certain tumor cells resisting chemotherapy or radiation, so a virus that can induce apoptosis despite defects in the cell cycle is useful for cancer treatment.
In short, the electrons of the atoms in the atomizer can be promoted to higher orbitals ( excited state ) for a short period of time ( nanoseconds ) by absorbing a defined quantity of energy ( radiation of a given wavelength ).
The radiation intensity emitted by these lamps is decreasing significantly with increasing wavelength, so that they can be only used in the wavelength range between 190 and about 320 nm.
This way any ( unmodulated ) radiation emitted for example by the atomizer can be excluded, which is imperative for LS AAS.
All these phenomena, molecular absorption and radiation scattering, can result in artificially high absorption and an improperly high ( erroneous ) calculation for the concentration or mass of the analyte in the sample.
The advantage of this technique is that only one radiation source is used ; among the disadvantages are that the high-current pulses reduce lamp lifetime, and that the technique can only be used for relatively volatile elements, as only those exhibit sufficient self-reversal to avoid dramatic loss of sensitivity.
Because individuals with albinism have skin that entirely lacks the dark pigment melanin, which helps protect the skin from the sun's ultraviolet radiation, their skin can burn more easily from overexposure.
Despite its invisible interior, the presence of a black hole can be inferred through its interaction with other matter and with light and other electromagnetic radiation.
CRTs can emit a small amount of X-ray radiation as a result of the electron beam's bombardment of the shadow mask / aperture grille and phosphors.
When exposed to sunlight, artificial light, or infrared radiation ( even the heat of a hand nearby can be enough ), the vanes turn with no apparent motive power, the dark sides retreating from the radiation source and the light sides advancing.
At these very high vacuums the effect of photon radiation pressure on the vanes can be observed in very sensitive apparatus ( see Nichols radiometer ) but this is insufficient to cause rotation.
A Crookes radiometer, consistent with the word-element " meter " in its title, can provide a quantitative measurement of electromagnetic radiation intensity.
Earth creatures ( such as animals, plants and even humans ) exposed to Tiberium can either be killed because of the radiation or be transformed into Tiberium-based life-forms, to whom Tiberium radiation is curative rather than toxic.
Employing shorter wavelengths implied abandoning microscopy and true imaging, however, because there exists no material from which a lens capable of focusing this type of radiation can be created.
The process can also be used to detect radiation that initiates the process, as the passage of a single particles can amplified to large discharges.
0.149 seconds.