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Abstract: PE-g-HEMA films prepared by the mutual gamma irradiation method were prepared to be used as catalyst support in catalytic membrane reactors (CMR). These copolymeric films showed good structural stability, even the high grafted ones, with a consistent correlation between their grafting degree and crystallinity. However, it was observed that above a certain radiation dose threshold, the structural changes induced in polyethylene (PE) backbone do not depend only on the extend of poly(HEMA) graft but also in what seems to be the reorganization of the amorphous regions in the PE matrix. The recovery of some crystallinity (up to 8%) in the copolymeric films was attested by DSC data. FTIR analysis confirmed this observation, revealing a slight increase in intensity and definition of the characteristic peak indicator of high crystalline regions in PE. This process seems to result from a radiation protective effect on copolymers matrix carried out by grafted poly(HEMA) which give to PE the ability to recover some of the lost structural order. [Copyright &y& Elsevier]

Abstract: PE-g-HEMA films with different grafting yields prepared by mutual gamma irradiation method at a 60Co source were characterized with ion beam analytical techniques using a nuclear microprobe. Qualitative analysis showed a random and heterogeneous distribution of contaminant elements, independent of the grafting degree, suggesting the existence of several sources of contamination at different stages of their preparation. Results also suggest that this “phased” contamination occurs simultaneously with mechanisms of agglomeration/entrapment of impurities during the gamma induced copolymerization reaction. Moreover, quantitative data showed that all contaminants found in the copolymeric films are natural contaminants of their reagents of preparation, although at concentrations without toxicological hazard, which points to a low cytotoxic potential. [Copyright &y& Elsevier]

Abstract: As a polysaccharide of natural origin, chitosan has the inherent properties of being biocompatible, biodegradable, and non-toxic. These properties make chitosan an ideal candidate for based backbone in copolymeric matrices for use in biomedical applications. Poly(hydroxyethyl methacrylate) is a synthetic hydrogel which possesses a high mechanical strength. The conjunction of these two components results in a new matrix that combines the useful properties of the synthetic pHEMA and natural chitosan. In this work chitosan/pHEMA membranes were obtained and γ-irradiated under nitrogen atmosphere. The effect of various synthesis conditions on the chemical, physical and biological properties was evaluated. The chitosan/pHEMA membranes were characterised using FTIR spectroscopy, scanning electron microscopy and thermal analysis techniques. Its hydration capacity and its antimicrobial properties were also determined. The obtained results showed that the hydration capacity decreases in the irradiated membranes. It was also found that chitosan/pHEMA membranes present good barrier properties against microbes. [Copyright &y& Elsevier]

• The degradation of acetovanillone was studied using gamma radiation. • The degradation of acetovanillone was dependent of solution concentrations. • The degradation of acetovanillone was almost complete at 20 kGy for low concentration solutions, while for high concentration solutions acetovanillone was still detected at 50 kGy. • A degradation mechanism was proposed. The acetovanillone degradation, a toxic by-product of lignin present in cork and paper wastewaters, was studied using gamma radiation as an advanced oxidation process. The main by-products were identified and a tentative mechanism was proposed. Results showed that solution concentrations affected the radiolytic response including the by-products formed. At higher applied dose (50 kGy), acetovanillone was still observed in solutions of high initial concentration while, for low concentration, 20 kGy was enough to completely degrade this compound. Furthermore, at high concentration the predominantly reaction pathways led to structural changes in the benzene ring. At low concentration, the dominate reactions involved breaking of the benzene ring. These promising results demonstrated that gamma radiation can be used for an effective degradation of acetovanillone and provided better insight into the reaction mechanisms for other recalcitrant compounds. [ABSTRACT FROM AUTHOR]

Abstract: With the purpose of obtaining a biocompatible and microbiologically safe matrix that simultaneously could be used as wound dressing material and as a controlled drug release system, membranes with different thickness and different contents in chitosan and hydroxyethyl methacrylate (HEMA) have been prepared by γ irradiation from a 60Co source. Antibiotic release experiments were performed before or after irradiation over amoxicillin loaded chitosan/pHEMA membranes in physiological saline solution, and monitored by UV–Vis spectrometry. Results point out a fast amoxicillin release with similar release profile in all studied membranes. The amount of released drug was shown to be dependent on membranes network crosslinking due composition, radiation and membrane thickness. [Copyright &y& Elsevier]