| http://www.w3.org/ns/prov#value | - In a similar manner, therefore, it is possible to protect the photochromic dye imbibed in a resinous material by a coating, for instance, of titanium dioxide and thereby prevent the adverse effect of oxygen or water vapor or other deleterious chemicals on the photochromic materials when subsequently dispersed within a plastic material and utilized in an ophthalmic or optical device.
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