Role of primary reaction initiated by 254 nm UV light in the degradation of p-nitrophenol attacked by hydroxyl radicals.
The degradation kinetics of p-nitrophenol (p-NP) exposed to 254/185 nm UV light were studied in two modes, i.e., 254 nm UV light intensity enhanced mode and normal mode. It was observed that the extra 254 nm UV light source accelerated the degradation process both in the presence and the absence of oxygen. Considering that hydroxyl radical (*OH) is the dominant factor that causes the degradation of p-NP, the enhanced degradation that occurred in the presence of the extra light source was attributed to the synergistic effect between *OH attack and the primary reactions initiated by 254 nm UV light. The synergistic effect has been confirmed by 266 nm laser flash photolysis (LFP) experiments. It is demonstrated that the phenoxy radical generated from the photoionization of p-NP is capable of reacting with *OH. On the basis of these results, it should be noted that UV light could cause more severe damage to p-NP attacked by *OH in aqueous solution.
Study on the role of hydroperoxyl radical in degradation of p-nitrophenol attacked by hydroxyl radical using photolytical technique
In order to investigate the possible role of hydroperoxyl radical (HO2 center dot) in the degradation of p-nitrophenol (p-NP) attacked by hydroxyl radical ((OH)-O-center dot), a series of experiment have been elaborately designed using UV light photolysis, pulse radiolysis and intermediate analysis. It has been demonstrated that (OH)-O-center dot is the dominant reactive oxygen specie, meanwhile both O-2 and HO2 center dot can enhance the degradation efficiency of p-NP. The accelerative effect of HO2 center dot has firstly been distinguished from that of O-2 by identifying the products in the systems of p-NP + (OH)-O-center dot, p-NP + (OH)-O-center dot + O-2 and p-NP + (OH)-O-center dot + O-2 + HO2 center dot. The possible reaction mechanism involved in the degradation of p-NP has been proposed, especially in the presence and absence of HO2 center dot. The ring open of phenoxy-type radical may be the key step in the accelerative effect of HO2 center dot. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.
Mechanics of deformable directed surfaces
Abstract The paper develops a simple, yet complete and consistent non-linear dynamic thermo-elastic shell theory based on the concepts of a two-dimensional directed continuum. The constitutive equations are postulated in a general form. Stress-strain relations are derived using the equation of energy balance and the two entropy production inequalities, which are rewritten in a special form. The linear theory is discussed in detail. The structure of the stress-strain relations is presented in the most general form and then specialized to concrete examples, in particular, to the classical shell theory, using their invariance properties with respective to certain symmetry groups. The elastic moduli are determined by demanding the coincidence of the frequency dispersion surfaces obtained using the two-dimensional theory with the lowest foils of the corresponding surfaces resulting from the three-dimensional theory of elasticity.