Water, oxygenated, radiolysis

Preliminary safety analyses have been performed (Barinov et al., 2009). Both RDIPE concepts rely on the following materials and water chemistry solutions exclusion of copper-containing alloys and use a titanium condenser neutral water chemistry with demineralization of turbine condensate and oxygen injection into condensate to reduce transport of corrosion products and suppression of water coolant radiolysis by injection of gaseous hydrogen, ammonia, or hydrazine into feed water. 

Von Sonntag and coworkers17 extended this study to the radiolysis of an aqueous solution of 1,4-cyclohexadiene saturated with N20 02 (4 1) mixture. Due to the higher solubility of N2O in water all the hydrated electrons react with N2O to give OH radicals, as in N20-saturated solution. However, the concentration of oxygen is sufficient... 

Bobrowski and Das33 studied the transient absorption phenomena observed in pulse radiolysis of several retinyl polyenes at submillimolar concentrations in acetone, n -hexane and 1,2-dichloroethane under conditions favourable for radical cation formation. The polyene radical cations are unreactive toward oxygen and are characterized by intense absorption with maxima at 575-635 nm. The peak of the absorption band was found to be almost independent of the functional group (aldehyde, alcohol, Schiff base ester, carboxylic acid). In acetone, the cations decay predominantly by first-order kinetics with half life times of 4-11 ps. The bimolecular rate constant for quenching of the radical cations by water, triethylamine and bromide ion in acetone are in the ranges (0.8-2) x 105, (0.3-2) x 108 and (3 — 5) x 1010 M 1 s 1, respectively. 

Daniels M, Wigg E (1966) Oxygen as a primary species in radiolysis of water. Science 153 1533-1534... 

Generally, the reduction is achieved under deaerated conditions to avoid a competitive scavenging of Cjoiv and H atoms by oxygen. These atoms are as homogeneously distributed as the ions and the reducing species, and they are therefore produced at first as isolated entities. Similarly, multivalent ions are reduced by multistep reactions, including disproportionation of intermediate valencies. Such reduction reactions have been observed directly by pulse radiolysis for a variety of metal ions (Fig. 2), mostly in water [28], but also in other solvents where the ionic precursors are soluble. Most of their rate eonstants are known and the reactions are often diffusion controlled. 

In the absence of oxygen, effects of pH on the polymer are complicated by possible effects of pH on yields of hydrogen atoms from the radiolysis of water. However, it is difficult to see how the increase in hydrogen atom yield at low pH could lead to a decrease in yield of D-glutamate and glycine. If these were formed by intermolecular reactions—e.g., Reaction 22 for forming D-glutamate—the explanation put forward by Sokol et al. to account for the effects in O2 could also explain the observations on yields in the absence of 02. 

Reports indicated that the phenolase responsible for melanogenesis of shrimp was located in the shell and concentrated primarily at the joints between segments. It was concluded that water and oxygen may diffuse through these joints, and that their radiolysis products were responsible for the inactivation of phenolase and subsequent reduction of melanosis. 

Chatterjee A, Magee JL (1985) Theoretical investigation of the production of strand breaks in DNA by water radicals. Radiat Protect Dosimetry 13 137-140 Deeble DJ, von Sonntag C (1984) y-Radiolysis of poly(U) in aqueous solution. The role of primary sugar and base radicals in the release of undamaged uracil. Int J Radiat Biol 46 247-260 Deeble DJ, von Sonntag C (1986) Radiolysis of poly(U) in oxygenated solutions. Int J Radiat Biol 49 927-936... 

All amino-acid residues of proteins are potential targets for attack by reactive oxygen species (ROS) produced in the radiolysis of water however, in only a few cases have the oxidation products been fully characterized. Moreover, under most physiological conditions, cysteine, methionine, arginine, lysine, proline, histidine, and the aromatic amino acids are primary targets for ROS-mediated oxidation. 

Pulse radiolysis is a method that determines the reactivity of the unstable radical species produced by radiation using an electron pulse. When oxygenated water is irradiated with an electron pulse of 10 8 10 6-s duration in the presence of formate, 05 is produced by the following equations. 

Radiolysis has been used successfully in order to synthesize various noble (such as silver, gold and platinum) and non-noble (such as nickel and iron) metal nanoparticles in aqueous solution and also in other solvents such as alcohols. Due to their relatively low redox potential compared to that of the bulk, metal clusters can be oxygen-sensitive. However, the deoxygenation (by bubbling with an inert gas such as argon or nitrogen) of the solutions prior to irradiation and their study under inert atmosphere prevent their oxidation. Moreover, since water radiolysis leads to the formation of protons in addition to that of hydrated electrons, radio-induced acidification of the medium may lead to non-noble metal clusters corrosion. Therefore, to avoid the oxidation by protons, the solutions can be prepared in slightly basic medium. 

---