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Topic: Ultraviolet light


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  Ultraviolet - Wikipedia, the free encyclopedia
Fluorescent fl lights are typically made in the same fashion as normal fluorescent lights except that only one phosphor is used instead of the typical 2 or 3 which produce a full spectrum light and the normally clear glass envilope of the bulb is replaced by a deep bluish purple glass called Wood's glass.
Ultraviolet radiation is used for very fine resolution photolithography, a procedure where a chemical known as a photoresist is exposed to UV radiation which has passed through a mask.
Ultraviolet (UV) detectors generally use either a solid-state device, such as one based on silicon carbide or aluminum nitride, or a gas-filled tube as the sensing element.
en.wikipedia.org /wiki/Ultraviolet   (2848 words)

  
 Ultraviolet Light   (Site not responding. Last check: 2007-11-06)
Ultraviolet light is a form of radiation which is not visible to the human eye.
All of the X-rays, gamma-rays and ultraviolet light emitted by stars are absorbed by the Earth's atmosphere.
Many scientists are interested in studying the invisible universe of ultraviolet light, since the hottest and most active objects in the universe give off large amounts of ultraviolet energy.
liftoff.msfc.nasa.gov /academy/universe/ultraviolet.html   (380 words)

  
 [No title]   (Site not responding. Last check: 2007-11-06)
The one disease that did not respond to treatment with light transfusion was a severe infection involving the heart called bacterial endocarditis, Even now, this is regarded as a grave illness with a serious risk of mortality, and a high proportion of damage to the heart in those patients who survive.
Over the next thirty years it was established that the ultraviolet component of the solar spectrum had this effect, and that it was effective in killing off a number of the most important micro-organisms then known to science.
In 1935 it was shown that using ultraviolet lights in a surgical operating theatre could kill all bacteria within ten minutes, even though it would take one and a half hours for the most sensitive skin to go red.
www.bio-immuno-development.com /books/daylight/925.htm   (2806 words)

  
 Ultraviolet Waves
The three regions are distinguished by how energetic the ultraviolet radiation is, and by the "wavelength" of the ultraviolet light, which is related to energy.
The near ultraviolet, abbreviated NUV, is the light closest to optical or visible light.
The extreme ultraviolet, abbreviated EUV, is the ultraviolet light closest to X-rays, and is the most energetic of the three types.
imagers.gsfc.nasa.gov /ems/uv.html   (649 words)

  
 3rdPlanetSamples.com - Ultraviolet Rocks and Minerals short-wave longwave and germicidal ultraviolet light bulbs lamps, ...   (Site not responding. Last check: 2007-11-06)
Ultraviolet light is electromagnetic radiation in a part of the spectrum between X-rays and visible light, approximately 180 nanometers to 400 nanometers.
When certain atoms are exposed to ultraviolet (UV) light, a photon (particle of light energy) of UV will cause an electron residing in a lower-energy inner electron shell to be temporarily boosted to a higher-energy outer shell.
When ultraviolet light rays collide with a contaminant such as carbon monoxide (CO) and nitrogen oxides (NO2 and N2O) in the presence of oxygen (O2), ozone is produced.
www.3rdplanetsamples.com   (1317 words)

  
 Gale Encyclopedia of Medicine: Ultraviolet light treatment
Ultraviolet light treatment uses a particular band of the nonvisible light spectrum to treat psoriasis and a variety of other skin diseases.
Ultraviolet (UV) light treatment is used primarily in cases of severe psoriasis that have not responded to other medications or in cases affecting large portions of the body.
Other skin conditions treated with UV light treatments are vitiligo, a condition in which people lose pigmentation in large patches of their skin, and atopic dermatitis, an allergy-related skin condition that produces itchy, reddish, and scaly patches of skin.
www.findarticles.com /p/articles/mi_g2601/is_0014/ai_2601001420   (1315 words)

  
 UV Radiation   (Site not responding. Last check: 2007-11-06)
All energies that move at the speed of light are collectivelly referred to as electromagnetic radiation or 'light'.
Another possible responce of plankton is to sink deeper into the water but this reduces the amount of visible light they need for photosynthesis, and thereby reduces their growth and reproduction rate.
Ultraviolet levels are over 1,000 times higher at the equator than at the polar regions so it is presumed that marine life at the equator is much better adapted to the higher enviromental UV light than organisms in the polar regions.
www.nas.nasa.gov /About/Education/Ozone/radiation.html   (1014 words)

  
 Ultraviolet
The main use of ultraviolet is in the manufacturing integrated circuits.
Artificial sources of ultraviolet light are often used to stimulate the effects of solar ultraviolet radiation in the study of the deterioration of materials on exposure to sunlight
Ultraviolet waves are used to identify materials by the glow or fluorescence under them.
www.smgaels.org /physics/uv_1.htm   (551 words)

  
 FDA/CFSAN: Kinetics of Microbial Inactivation for Alternative Food Processing Technologies -- Ultraviolet Light
Ultraviolet processing involves the use of radiation from the ultraviolet region of the electromagnetic spectrum for purposes of disinfection.
The germicidal properties of ultraviolet irradiation are due to the DNA absorption of the UV light, causing crosslinking between neighboring pyrimidine nucleoside bases (thymine and cytosine) in the same DNA strand (Miller and others 1999).
Ultraviolet light from germicidal lamps was exposed to inoculated apple cider by passing it through the processing tube at a constant flow rate.
vm.cfsan.fda.gov /~comm/ift-uv.html   (2775 words)

  
 Ultraviolet Light (UV) Air Purifier
The Centers of Disease Control (CDC) recommends the use of ultraviolet light with simultaneous use of HEPA air filters, both of which are offered in the Multi-Tech XJ-3000C air purifier.
The Air Institute of Respiratory Education suggests UV lights be used in buildings for indoor air quality purposes, and states that may be the final line of defense against those diseases that have developed resistance to drugs, such as tuberculosis and others.
The UV lights, which were installed in the ventilation system, were operated in three cycles of four weeks on, twelve weeks off.
www.surroundair.com /uv-light.htm   (433 words)

  
 Reading on Absorption and Fluorescence
The photon is "lost" from the light beam as it is absorbed, and the electron is excited to an available higher energy state by the gain in energy from the photon.
The absorption of light photns of high energy and re-emission of photons of lower energy, in the visible region, is commonly called fluorescence.
Illustration of the fluorescence process: An incident ultraviolet photon is absorbed and transfers its energy to an electron (process 1), the electron loses some of its energy in non-radiative processes, 2, and then the electron makes a transition to the ground state, process 3, emitting a photon with energy in the visible region.
acept.la.asu.edu /PiN/rdg/irnuv/irnuv.shtml   (1459 words)

  
 Electromagnetic Spectrum
In interactions with matter, visible light primarily acts to set elevate electrons to higher energy levels.
White light may be separated into its spectral colors by dispersion in a prism.
The sun is a strong source of ultraviolet radiation, but atmospheric absorption eliminates most of the shorter wavelengths.
hyperphysics.phy-astr.gsu.edu /hbase/ems3.html   (537 words)

  
 Bacteria in Drinking Water, Bulletin 795 - Ultraviolet   (Site not responding. Last check: 2007-11-06)
Water is passed through a disinfecting chamber containing a quartz mercury lamp that emits ultraviolet light rays.
Some units are equipped with UV detectors to warn the user when the unit is dirty or the light source is failing.
Careful Use of UV Since the ultraviolet light must reach the bacteria in order to kill them, the light source must be kept clean.
ohioline.osu.edu /b795/b795_9.html   (346 words)

  
 Mount Washington Observatory: Glossary of Weather Terms   (Site not responding. Last check: 2007-11-06)
Ultraviolet is subdivided into near (NUV) 400 to 300 nanometers, far (FUV) 300 to 200 nanometers, extreme (XUV) 200 to 100 nanometers, and vacuum (VUV) 100 to 4 nanometers.
In the daytime, one evaluates a dark object against the horizon whereas at night, one evaluates a bright object which is emitting or reflecting light.
This results in an object losing contrast in the daytime (due to increased air brightness from sunlight scattering off the air in front of the object) or becoming dimmer at night (because light emitted or reflected from the object is being scattered on its way to the eyes).
www.mountwashington.org /glossary/glosu-z.html   (1107 words)

  
 Ultraviolet light to squeeze in the data (June 2001) - News - PhysicsWeb
Zinc oxide has a large energy gap that allows it to emit blue light, but when the nanowires are excited by another laser they emit ultraviolet light with a wavelength of 385 nm.
The laser cavity that amplifies the light is formed by the reflecting interfaces between the nanocrystal and the sapphire substrate at one end, and the surrounding air at the other.
Excitons recombine within the LED to emit ultraviolet light with a wavelength of 235 nm.
physicsweb.org /article/news/5/6/3   (495 words)

  
 Ultraviolet light: is it harming New Zealand's lakes? - NIWA   (Site not responding. Last check: 2007-11-06)
UV light is at the short-wavelength end of the spectrum.
The squiggly lines on this figure represent the energy the light has: the tighter the squiggle, the higher the energy and the greater the chances of the light harming life on Earth.
Ultraviolet light (UV) has the shortest wavelengths (measured in nanometres: nm), and is subdivided into three bands: A, B, and C. UV-A along with PAR (photosynthetically available radiation, also called visible light) and IR (infrared radiation) are not absorbed by the ozone layer even when it is thick and healthy.
www.niwa.cri.nz /pubs/wa/09-1/uv.htm   (1627 words)

  
 Germicidal and Specialty Fluorescent Lamps from Light Sources
 Light Sources is the world leader in the design and manufacture of low pressure quartz germicidal lamps, ozone generation, specialty fluorescent and unique application gas-discharge lamps.
Light Sources is the leading producer of low-pressure UVC lamps in the 185 and 254mm wavelengths, for use in the purification of primary drinking water, industrial process ultrapure water and municipal wastewater disinfection.
Light Sources germicidal lamps are designed to provide the high performance required in demanding environments such as air and water purification, sewage treatment, protection of food, and many other kinds of disinfection and sterilization processes.
www.light-sources.com   (274 words)

  
 Ultraviolet Light, As Used in Fly Control, Trap Fruit Flies
When flies see ultraviolet light, they are naturally lured in the direction of the source of UV rays.
The light from an ultraviolet trap gives the fly the impression that it is flying in the easiest path.
The Exocutor Ultraviolet Fly Zapper and Insectaflash Ultraviolet Fly Zapper are excellent zappers; for areas that are hosed down regularly or where moist conditions are present the Splashproof Ultraviolet Fly Zapper is needed.
www.pestproducts.com /ultraviolet.htm   (501 words)

  
 ultraviolet light
Ultraviolet light is arbitrarily broken down into three bands, according to its anecdotal effects.
[Atmospheric effect on light] Ultraviolet light is a form of radiation which is not visible to the human eye.
… The as seen in "deep" ultraviolet light at 17.1 by the instrument aboard the spacecraft … UVC rays are the strongest, most dangerous type of ultraviolet light.
www.billywords.org /ultraviolet-light.html   (235 words)

  
 Pureflow Home Page   (Site not responding. Last check: 2007-11-06)
Ultraviolet irradiation or "UV light" as it is commonly called, is a proven technology that is used to solve microbiological problems in water.
Virtually all water treatment applications are candidates for the addition of ultraviolet light as a means of disinfection and microbial control.
Pureflow Ultraviolet Inc. is the largest stocking ultraviolet equipment distributor in North America.
www.pureflow.com   (168 words)

  
 Skin Protection from Ultraviolet Light Exposure
Over 90% of ultraviolet radiation is UVA, which is most intense in early morning and afternoon, can pass through window glass, penetrates into the dermis, and causes tanning and wrinkling.
Ultraviolet liglit hasbeen implicated in multiple human diseases from skin cancer tocataracts to immune suppression.
SPF is determined indoors using a light spectrum meant to mimic noontime sun; when tested outdoors, SPF may over-estimate sun protection by a factor of two, especially when the sun is close to the horizon owing to a changed ratio of UVA to UVB.
www.acpm.org /skinprot.htm   (2479 words)

  
 Howstuffworks "How Light Works"
We are, in fact, seeing light -- light that somehow left objects far or near and reached our eyes.
Light is all our eyes can really see.
The other way that we encounter light is in devices that produce light -- incandescent bulbs, fluorescent bulbs, lasers, lightning bugs, the sun.
science.howstuffworks.com /light.htm   (193 words)

  
 News Release - Sandia VCSEL generates ultraviolet light
Among their benefits, UV VCSELS (vertical-cavity surface-emitting lasers) coated with phosphors have the capability to generate the white light most prized for indoor lighting — illumination currently provided by gas-filled fluorescent tubes widely used in offices, schools, factories, and by incandescent bulbs used in most homes.
The process of emitting white light by VCSELS is similar to that in standard fluorescent tubes.
Blue LEDS already commercially available also give off white light through phosphors, but the light so rendered is considered a cold white because it is overbalanced toward the blue spectrum.
www.sandia.gov /media/NewsRel/NR2000/UVVCSEL.htm   (882 words)

  
 312-nanometer Ultraviolet B Light (Narrow-Band UVB) Induces Apoptosis of  T Cells within Psoriatic Lesions -- Ozawa et ...   (Site not responding. Last check: 2007-11-06)
Ultraviolet B light (UVB, 290-320 nm) is used as a therapeutic modality for psoriasis and other inflammatory skin disorders.
Successful ultraviolet B treatment of psoriasis is accompanied by a reversal of keratinocyte pathology and by selective depletion of intraepidermal T cells.
Biochemical pathways of apoptosis: nicotinamide adenine dinucleotide-deficient cells are resistant to tumor necrosis factor or ultraviolet light activation of the 24-kD apoptotic protease and DNA fragmentation.
www.jem.org /cgi/content/full/189/4/711   (3595 words)

  
 Biozone, UV Air Cleaner, Germicidal Air Cleaner, UV Light, Biozone Air Purifier, UV Air Purifier
There, they are immediately exposed to high intensity ultraviolet light that kills a wide range of bacteria, viruses, and molds, and helps break down unhealthy gases and vapors.
Second, special wavelengths of concentrated ultraviolet light are also used to kill bacteria, viruses and fungi.
When relatively too many positive ions are present in the air before a storm, the positive charge is transferred in the air you breathe from your lungs to the blood, causing the blood platelets to release a hormone that quite strongly affects your moods, your joints, and other physiological functions in your body.
www.peakpureair.com /biozone.htm   (2420 words)

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