Ultraviolet radiation titanium oxide

Sunscreens absorb ultraviolet radiation before it can be absorbed in the skin. They are recommended to protect the skin from the major toxicities of sun exposure sunburn and skin cancer. Most available agents primarily absorb UVB, although newer preparations also provide protection against UVA. Physical sunscreens (which are generally opaque, hke titanium dioxide and zinc oxide) block all ultraviolet radiation. 

Bellobono, I.R., P.L. Pinacci, G. Riva, and C. Lagrasta (1998). Pilot-plant photomineralization of. v-triazincs in aqueous solution, by pho-tocatalytic membranes immobilising titanium dioxide and trialkyl vanadates photocatalysts. Fresenius Environ. Bull., 7 277-288. Beltran, F.J., G. Ovejero, and B. Acedo (1993). Oxidation of atrazine in water by ultraviolet radiation combined with hydrogen peroxide. Wat. Res., 27 1013-1021. 

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... 

Titanium has gained worldwide importance in the food industry. Potassium tita-nate fibers were used as a filter aid for the production of Japanese sake (Ogino etal. 1989) and as paints for beverage cans in Japan (Osumi 1993). The high reflectivity of titanium oxide to both infrared and ultraviolet radiation makes it suitable for use in... 

Protection against changes in color or properties caused by ultraviolet radiation can be imparted by use of finely-divided grades of zinc oxide or titanium dioxide. Carbon black is effective where it can be used. A number of commercially available UV absorbers, including benzotrlazoles and benzo-phenones, are also useful in this connection. 

Antioxidants and UV absorbers (see Section 11.2) are also used as secondary PVC stabilizers [67]. They become necessary, since double bonds created in degraded PVC can absorb radiation in the ultraviolet range which energy is high enough to produce more dehydrochlorination. Furthermore, these radiations could decompose peroxides or hydroperoxides formed or already present in PVC and induce radical promoted oxidation of the polymer chains [68,69]. The wavelength range that may produce these undesired effects is believed to go from 310 to 400 nm [79-82]. UV absorbers used for PVC are mainly benzo-triazol, benzophenone derivatives, zinc oxide, and titanium oxide. 

Sunblocks are opaque substances such as zinc oxide, titanium dioxide, and iron oxide that protect by forming a shield on the skin, which reflects and scatters incident radiation. In essence, sunblocks provide physical protection against sun exposure, including both visible and ultraviolet light. Sunscreens are substances that chemically absorb ultraviolet light in the top layer of the epidermis, protecting the underlying layers. 

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