Ultraviolet radiation pigments

Light and Toxic Reactions In many individuals, exposure to ultraviolet radiation from the sun causes skin reactions such as erythema, thickening of the epidermis, and darkening of existing pigment. Exposure to ultraviolet light also increases the risk of different forms of skin cancers, especially malignant melanoma. ... 

Colonna, GM Caronna, T Marcandalli, B. Oxidative degradation of dyes by ultraviolet radiation in the presence of hydrogen peroxide. Dyes and Pigments, 1999 41,211-220. 

Another obvious genetic aspect of toxicology has to do with the level in skin of melanin, a pigment that makes skin dark. Melanin levels vary widely with genotype. Melanin confers resistance to the effects of solar ultraviolet radiation, which is absorbed by DNA in skin cells, causing damage that in the worst-case results in deadly melanoma skin cancer. Skin melanin is a chromophore (a... 

Due to these characteristics, these pigments are useful for the photostabilization of some white compounds, e.g. corticosteroids, whose photodegradation is only caused by absorption of ultraviolet radiation. As shown in Figure 25, the addition of 0.5% of titanium dioxide or zinc oxide leads to the effective photoprotection of... 

Epidermal cells are on the upper and lower surfaces of a leaf. They have two features which prevent evaporative water loss they are packed densely together and they are covered by a cuticle, a waxy layer secreted by the cells. The epidennis usually consists of a single layer of cells, although the specialized leaves of some desert plants have epidermal layers which are several cells thick. Epidermal cells often have large vacuoles which contain flavonoid pigments. Elavonoids generally absorb ultraviolet radiation, and may act as a sort of natural sunscreen for the internal layers of the leaf, by filtering out harmful ultraviolet radiation from the sun. 

They arc made of a laminated melaminealkyd core encapsulated in polyethylene wax. The core is colour coded by the inclusion of pigments. One of the layers contains iron particles to make the taggant magnet-sensitive and one or both exterior layers contain fluorescent compounds which respond to ultraviolet radiation. 

Finishes based on PVDF resin are formulated by licensed formulators and contain, in addition to PVDF resin, solvents and high quality pigments. These high quality coating systems have a proven history of performance when exposed to severe ultraviolet radiation for extended periods (over 30 yr) of time. 

Protection from UVR is available through the use of sunsceens and clothing. Sunscreen lotions contain UVR absorbers and sun blockers contain pigment that physically blocks UVR. Hats, sunscreens, sunglasses and clothing can be used to decrease the exposure to ultraviolet radiation by a factor of 10 or more, as well as by people avoiding exposure to the sun at its maximum [74]. 

C. Sebastian, R. Scheuerlein, D.-P. Hader (1994). Effects of solar and artificial ultraviolet radiation on pigment composition and photosynthesis in three Prorocentrum species. J. Exp. Mar. Biol. Ecoi, 182,251-263. 

H. Maske, M. Latasa (1997). Solar ultraviolet radiation dependent decrease of particle light absorption and pigments in lake phytoplankton. Can. J. Fish. Aquat. ScL, 54, 697-704. 

J. Aguilera, C. Jimenez, F.L. Figueroa, M. Lebert, D.-P. Hader (1999). Effect of ultraviolet radiation on thallus absorption and photosynthetic pigments in the red alga Porphyra umbilicalis. J. Photochem. Photobiol B Biol, 48, 75-82. 

L.A. Hansson (2000). Induced pigmentation in zooplankton a trade-off between threats from predation and ultraviolet radiation. Proc. Royal Soc. Lond. Ser B, 267, 2327-2331. 

P.R. Leavitt, R.D. Vinebrooke, D.B. Donald, J.P. Smol, D.W. Schinder (1997). Past ultraviolet radiation environments in lakes derived from fossil pigments. Nature, 388, 457-459. 

Zinc oxide is a white substance used as a pigment in rubber, sun-blocking ointments, and paint. It is added to plastics to make them less likely to be damaged by ultraviolet radiation and is also used as a dietary supplement. It can be made from the reaction of pure zinc and oxygen ... 

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