DSpace Collection:https://hdl.handle.net/10316/277222024-03-29T10:57:29Z2024-03-29T10:57:29ZLight-Activated Antimicrobial Surfaces Using Industrial Varnish Formulations to Mitigate the Incidence of Nosocomial InfectionsSantos, Madson R. E.Mendonça, Patrícia V.Branco, RitaSousa, RúbenDias, CarlaSerra, Arménio C.Fernandes, José R.Magalhães, Fernão D.Morais, Paula V.Coelho, Jorge F. J.https://hdl.handle.net/10316/949802023-09-08T08:51:29Z2021-02-17T00:00:00ZTitle: Light-Activated Antimicrobial Surfaces Using Industrial Varnish Formulations to Mitigate the Incidence of Nosocomial Infections
Authors: Santos, Madson R. E.; Mendonça, Patrícia V.; Branco, Rita; Sousa, Rúben; Dias, Carla; Serra, Arménio C.; Fernandes, José R.; Magalhães, Fernão D.; Morais, Paula V.; Coelho, Jorge F. J.
Abstract: Evidence has shown that hospital surfaces are one of the major vehicles of nosocomial infections caused by drug-resistant pathogens. Smart surface coatings presenting multiple antimicrobial activity mechanisms have emerged as an advanced approach to safely prevent this type of infection. In this work, industrial waterborne polyurethane varnish formulations containing for the first time cationic polymeric biocides (SPBs) combined with photosensitizer curcumin were developed to afford contact-active and light-responsive antimicrobial surfaces. SPBs were prepared by atom transfer radical polymerization, which allows control over the polymer features that influence antimicrobial efficiency (e.g., molecular weight), while natural curcumin was employed to impart photodynamic activity to the surface. Antibacterial testing against Gram-negative Escherichia coli revealed that glass surfaces coated with the new formulations displayed photokilling effect under white-light (42 mW/cm2) irradiation within only 15 min of exposure. In addition, it was observed a combined antimicrobial effect between the two biocides (cationic SPB and curcumin), with a higher reduction in the number of viable bacteria observed for the surfaces containing cationic SPB/curcumin mixtures in comparison with the one obtained for surfaces only with polymer or without biocides. The waterborne industrial varnish formulations allowed the formation of homogeneous films without the need for addition of a coalescing agent, which can be potentially applied in diverse surface substrates to reduce bacterial transmission infections in healthcare environments.2021-02-17T00:00:00ZHighly fluorinated erbium(III) complexes for emission in the C-bandMartín-Ramos, P.Ramos Silva, M.Lahoz, F.Martín, I. R.Chamorro-Posada, P.Eusebio, M. E. S.Lavín, V.Martín-Gil, J.https://hdl.handle.net/10316/278272021-10-15T07:47:17Z2014-10-15T00:00:00ZTitle: Highly fluorinated erbium(III) complexes for emission in the C-band
Authors: Martín-Ramos, P.; Ramos Silva, M.; Lahoz, F.; Martín, I. R.; Chamorro-Posada, P.; Eusebio, M. E. S.; Lavín, V.; Martín-Gil, J.
Abstract: Two highly fluorinated Er3+ complexes with three 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate (fod) groups and either bipyridine (bipy) or bathophenantholine (bath) as the ancillary ligand emitting at the C-band (third communication window for fiber transmission) are presented. These complexes are the result of a design process aimed at decreasing the vibrational quenching from high frequency oscillators. The structure of [Er(fod)3(bipy)] has been elucidated by single-crystal X-ray diffraction, while Sparkle/PM6 and Sparkle/PM7 semi-empirical calculations have been used to model the ground state geometry for [Er(fod)3(bath)]. Photoluminescence studies confirm sensitization of the Er3+ ions by antenna effect, leading to NIR emission at 1.53 μm. This energy transfer proves to be more efficient for [Er(fod)3(bath)] as a result of the bulkier and more rigid structure of bath diimide. The good thermal stability of the materials up to over 200 °C allows envisaging their use in erbium-doped waveguides, NIR-OLEDs or other optoelectronic devices.2014-10-15T00:00:00ZFormation stages of bcc (Fe44Co44)Sn12 extended solid solution by mechanical alloyingLoureiro, J. M.Costa, B. F. O.Malaman, B.Caër, G. LeDas, S.Amaral, V. S.https://hdl.handle.net/10316/277232020-05-29T10:04:33Z2014-01-01T00:00:00ZTitle: Formation stages of bcc (Fe44Co44)Sn12 extended solid solution by mechanical alloying
Authors: Loureiro, J. M.; Costa, B. F. O.; Malaman, B.; Caër, G. Le; Das, S.; Amaral, V. S.
Abstract: The synthesis of supersaturated bcc Fe44Co44Sn12 by mechanical alloying was followed by various techniques. Two stannides, CoSn5 and FeSn2 form first at interfaces. Tetragonal CoSn5, a very recently discovered stannide, is obtained here by a simple method. These stannides then dissolve and the ternary bcc alloy forms with a progressive and simultaneous dissolution of Co and Sn into bcc Fe.2014-01-01T00:00:00ZMolecular structure and polymorphism of a cyclohexanediol: trans-1,4-cyclohexanedimethanolRosado, Mário T. S.Maria, Teresa M. R.Castro, Ricardo A. E.Canotilho, JoãoSilva, Manuela RamosEusébio, M. Ermelinda S.https://hdl.handle.net/10316/276492020-05-25T12:49:44Z2014-10-01T00:00:00ZTitle: Molecular structure and polymorphism of a cyclohexanediol: trans-1,4-cyclohexanedimethanol
Authors: Rosado, Mário T. S.; Maria, Teresa M. R.; Castro, Ricardo A. E.; Canotilho, João; Silva, Manuela Ramos; Eusébio, M. Ermelinda S.
Abstract: This study aims to investigate the molecular structure and polymorphism of trans-1,4-cyclohexanedimethanol,
including the bi-axial/bi-equatorial equilibrium and the nature of the intermolecular H-bond networks in
condensed phases created by the hydroxyl group torsions. The full conformational space of the single
molecule was explored by MP2 calculations, showing that the optimized bi-equatorial conformers have
similar stability and the bi-axial ones have much higher energies. The hydroxymethyl substituents have
preference for gauche/anti or gauche+/gauche− conformations. Polymorphic forms were generated by
crystallization from solutions and by cooling the melt, which were characterized by a combination of
techniques: DSC, PLTM and XRD. Two polymorphs were isolated and their crystal structures were solved
by direct methods based on single-crystal X-ray analysis. Both were found to contain two of the most
stable conformers found in the computational calculations. The influence of H-bonding in the polymorphic
structures was verified by analysis of the structural differences between the geometries present in
the polymorphs determined by XRD and their single molecule counterparts resulting from the theoretical
calculations. The bi-axial conformations are destabilized over the bi-equatorial ones in isolated and
crystalline forms of trans-1,4-cyclohexanedimethanol.2014-10-01T00:00:00Z