In ozone reactions in aqueous solutions, • OH and O 2 •are often generated as short-lived intermediates and hydroperoxides are formed as labile or stable final products. Tertiary butanol reacts with ozone only very slowly but readily with • OH. In the presence of dioxygen, formaldehyde is a prominent final product, 30 ( 4%, whose ready determination can be used as an assay for • OH. Although dimethyl sulfoxide reacts much more readily with ozone, its fast reaction with • OH which gives rise to methanesulfinic acid can also be applied for the determination of • OH, at least in fast ozone reactions. The formation of O 2 •can be assayed with tetranitromethane (TNM), which yields nitroform anion (NF -) at close to diffusion-controlled rates. TNM is stable in neutral and acid solution but hydrolyzes in basic solution (k ) 2.7 M -1 s -1 ), giving rise to NFplus nitrate ion (62%) and CO 2 plus 4 nitrite ions (38%). TNM reacts with O 3 (k ) 10 M -1 s -1 ), yielding 4 mol of nitrate (plus CO 2 ) and 4 mol of O 3 are consumed in this reaction. NFreacts with O 3 (k ) 1.4 × 10 4 M -1 s -1 ) by O-transfer. The resulting products, (NO 2 ) 3 COand (NO 2 ) 2 CdO, rapidly hydrolyze (k > 10 s -1 ), and most of the nitrite released is further oxidized by ozone to nitrate. In the case of slow ozone reactions, these reactions have to be taken into account; i.e. the NO 3yield has to be measured as well. For the determination of hydroperoxides, Fe 2+ -based assays are fraught with considerable potential errors. Reliable data may be obtained with molybdate-activated iodide. The kinetics of this reaction can also be used for the characterization of hydroperoxides. Reactive hydroperoxides undergo rapid O-transfer to sulfides, e.g., k(HC(O)OOH + (HOCH 2 CH 2 ) 2 S] ) 220 M -1 s -1 , and the corresponding reaction with methionine may be used for their quantification (detection of methionine sulfoxide by HPLC). Distinction of organic hydroperoxides and H 2 O 2 by elimination of the latter by reaction with catalase can often be used with advantage but fails with formic peracid, which reacts quite readily with catalase (k ) 1.3 × 10 -3 dm 3 mg -1 s -1 ). Some examples of • OH and O 2 •formation in ozone reactions are given.

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Nanocomposite UV coatings with adjustable properties for use on wood substrates in outdoor conditions were developed. Nanoscale ZnO was shown to be an efficient light absorber. Coatings were characterized in terms of elongation at brake, residual PI and double bond conversion, universal hardness, transparency, hydrophobicity, and yellowing. Coated samples were artificially weathered and studied with regard to their optical and mechanical properties, as well as to changes in brightness, transparency, hydrophobicity, and water permeability. The prepared wood coatings showed an increased weather fastness and improved optical properties. The suitability for use in outdoor conditions was assured by optimizing the elasticity of the coating and decreasing its water permeability.magnified image