Search

The biofouling of marine structures presents a problem for maritime industries, including increasing fuel and operational costs. There has been much work developing and evaluating chemically ‘ambiguous’ amphiphilic coatings based upon hydrophobic fluoropolymer and hydrophilic poly(ethylene glycol) (PEG). Many of these coatings have shown good fouling-release performance against diatoms, which present a fouling challenge to commercially-available state-of-the-art silicone-based fouling-release coatings. However, PEG is prone to oxidation, which limits its practical use in the marine environment, and thus an alternative hydrophilic material would be desirable in the future development of amphiphilic coatings. In this regard, zwitterionic materials are emerging as a promising class of hydrophilic antifouling material, which we hypothesized would be a suitable alternative to PEG within amphiphilic coatings. To test this hypothesis, cross-linked amphiphilic films consisting of commercially available perfluoropolyethers and the zwitterionic monomer sulfobetaine methacrylate were developed and studied. The difficulty in formulating these chemically incompatible species was overcome by careful choice of solvents and a series of prototype cross-linked films were prepared in which increasing quantities of zwitterion were systematically incorporated. The fouling-release performance of these films was tested against the diatom Navicula incerta, a common microfouling organism responsible for the formation of so-called ‘slime’ layers, and antifouling performance with cypris larvae of two barnacle species, Balanus amphitrite, and Balanus improvisus. To expand the scope of the study, the clinically-relevant biofilm-forming pathogen Staphylococcus aureus, which is a major culprit in the infection and failure of millions of indwelling medical devices, was also evaluated. Results indicate that the incorporation of zwitterion into perfluoropolyethers leads to significant improvements in fouling-release performance and these amphiphilic coatings display potential in fouling-release applications.

The ICRP Publication 118 introduced new threshold doses for tissue reactions and other non cancer effects on lens:the new threshold doses resulted significantly lower than previous scientific evidences. Lenses are often involved in brain radiotherapy treatment volumes and the risk of cataratta becomes relevant. Our study compares the results obtained from treatment plans calculated with both Rapid Arc technique and a new SSW IMRT template, for each patient recruited in the study, in terms of lens maximum absorbed doses. 10 patients with brain tumours diagnosis (PTV medium size af about 90 cc) localized in different areas were treated with the new SSW IMRT template, that consists in five fields spreading over a The dose prescription for all patients was 60 Gy in 2 Gy daily fractions. On the same patients, Rapid Arc plans were conformed with equal optimization objectives. The target coverage was at least 97% of prescription dose to 95 % of volume in both calculated plans. All the patiens treated with the SSW IMRT technique received a lower maximum omolateral lens dose (range from 0.4 to 2.4 Gy; mean value 1.7 Gy) compared to doses obtained with Rapid Arc plans (range from 0.5 to 4.4 Gy; mean value 2.4 Gy). Relatively to contralateral dose lens, we obtained a mean value of max dose of 1.5 Gy (range 0.4–2.2 Gy) for SSW IMRT plans and 2.2 Gy (range 0.5–4.6 Gy) for Rapid Arc plans. Patients treated with the new SSW IMRT template showed a lens dose sparing of about the 28% compared to doses they would have received with Rapid Arc plans.The other OAR involved as chiasm, optical nerve and brainstem are widely lower than the corresponding constraints. The new SSW IMRT template could be applied to treat target with different size, shape and anatomical position. Furthermore, the lens maximum dose reduction could potentially reduce the risk of cataract.

Hydroxy bifunctional fluoropolyether oligomers (ZDOL) are presented suitable for use as resins or for the preparation of polyurethane, polyester and polyether higher OH functionality resins. The synthesis procedures are described and discussed, and the effect of fluorine content and resin structure on glass transition temperature Tg and viscosity of final resin is stressed. It appears that the highly fluorinated polyether type resins, like the tetraolic derivative (TOL) and its mixtures with ZDOL, are characterized by only one, extremely low Tg and minimum viscosity values. Solvent–resin interactions and criteria for obtaining compatibility with polyisocyanate crosslinkers are discussed, pointing out the key role of hydrogen bonding. High solid coatings (solvent content less than 30%) are obtained by curing with blocked aliphatic polyisocyanates, and a preliminary characterization of final materials based on their thermal transitions and mechanical properties is reported.