Esr Studies of the Low Temperature Irradiation of Keratin and Its Component Amino Acids

Abstract

Abstract— The photoejection of electrons from the aromatic amino acids at 77°K by 290–340 nm radiation was found to involve both monophotonic and biphotonic processes. However, only monophotonic processes are involved when electrons are photoejected from cystine or cysteine. These electrons prefer to attach themselves to adjacent sulphur groups rather than the dielectric traps in the matrix, so that both anionic and cationic radicals are formed. In keratin at 77°K, the disulphide anion radicals are produced by both monophotonic and biphotonic mechanisms, indicating that the electrons captured by the disulphides are photo‐ejected from the aromatic amino acids. At room temperature the thiyl and aromatic radicals are produced only by monophotonic reactions.

Improving Wool Printability at Reduced Energy using UV/ozone Treatment

“…The results verified the effect of UV/ozone exposure on decreasing the strength of the irradiated samples and hence their ability to pass air through its structure that is, increasing their air permeability values (Pailthorpe & Nicholls, 1972). The nature of increased air permeability via the UV/ozone treatment of wool fabric samples is related to surface oxidation creating polar groups and modifying or volatilizing surface lipids .Also, previous studies showed that UV/ozone causes photo-oxidation that mainly modifies C 21 fatty acid components of wool surface lipids and oxidizes disulphide (Hawkyard et al, 1997).…”

Investigation into the synergistic effect between UV/ozone exposure and peroxide pad—batch bleaching on the printability of wool

“…A great deal of research about UV irradiation of wool involved mainly its 'negative' effects in terms of photoyellowing and photodegradation [6][7][8][9]. Recently, the beneficial effects of UV irradiation have been reported.…”

Towards an insight on photodamage in hair fibre byUV‐light: An experimental and theoretical study

“…Cystine is a quenching agent for Tyr; previous research [37] has demonstrated that the quenching mechanism occurs via an electron transfer process with the formation of the radical anion RSSR˙À Although the excited Trp undergoes intersystem crossing to triplet states, studies on wool have suggested that singlet states are quenched more effectively than triplet states [38]. However, there is no evidence of an energy transfer from Trp to cystine in an aqueous system during irradiation [34].…”