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ultraviolet |
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ultraviolet /ul·tra·vi·o·let/ (UV) (ul?trah-vi´o-let) denoting electromagnetic radiation between violet light and x-rays, having wavelengths of 200 to 400 nanometers. UVA is that from 320 to 400 nm, UVB is that from 290 to 320 nm, and UVC is that from 200 to 290 nm. ultraviolet A (UVA) ultraviolet radiation with wavelengths between 320 and 400 nm, comprising over 99 per cent of that reaching the surface of the earth. It enhances the harmful effects of UVB, is responsible for some photosensitivity reactions, and is used therapeutically in the treatment of various skin disorders. ultraviolet B (UVB) ultraviolet radiation with wavelengths between 290 and 320 nm, comprising 1 per cent of that reaching the surface of the earth. It causes sunburn and a number of damaging photochemical changes within cells, including damage to DNA leading to premature aging of the skin, premalignant and malignant changes, and various photosensitivity reactions; it is also used therapeutically in the treatment of skin disorders. ultraviolet C (UVC) ultraviolet radiation with wavelengths between 200 and 290 nm, all of which is filtered out by the ozone layer and does not reach the surface of the earth; it is germicidal and is also used in ultraviolet phototherapy.
ultraviolet (UV), n electromagnetic radiation that has shorter wavelengths than visible light; used in chemical analytical techniques and antisepsis. ultraviolet (UV) spectroscopy, n method used to measure the absorption of ultraviolet light (UV) in wavelength units to identify substances within a mixture. See also ultraviolet (UV). ultraviolet denoting electromagnetic radiation of wavelength shorter than that of the violet end of the spectrum, having wavelengths of 4-400 nanometers. ultraviolet antisepsis because ultraviolet rays are capable of killing bacteria and other microorganisms, they are sometimes utilized in specially designed cabinets to sterilize objects, and may also be used to sterilize the air in operating rooms and other areas where destruction of bacteria is necessary. ultraviolet irradiation the projection of ultraviolet light from a generator is used for the treatment of skin disease and for sterilization of materials. ultraviolet rays electromagnetic radiation beyond the violet end of the visible spectrum (at 0.39 to 0.18 µm wavelength) and therefore not visible to humans. They are produced by the sun but are absorbed to a large extent by particles of dust and smoke in the earth's atmosphere. They are also produced by the so-called sun lamps. Ultraviolet rays can produce sun-burning and affect skin pigmentation. When they strike the skin surface, these rays transform provitamin D, secreted by the glands of the skin, into vitamin D, which is then absorbed into the body. ultraviolet therapy the employment of ultraviolet radiation in the treatment of various diseases, particularly those affecting the skin, is used in humans, but not commonly employed in veterinary medicine. |
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NIST researchers have uncovered a potentially serious optical problem affecting designs for future generations of semiconductor manufacturing equipment using deep ultraviolet light. As the industry continues to grow, we will continue our ongoing efforts to provide the best, leading excimer laser light sources for deep ultraviolet (DUV) lithography, to support high-quality chip production. NIST now has the capability to accurately measure pulse-energy density of deep ultraviolet radiation produced by excimer lasers; this new capability is being used to provide dose (i. |
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