Phenoxy resin-based vinylogous urethane covalent adaptable networks

This work presents a post-polymerization approach to the preparation of vitrimers, exploiting the transamination of vinylogous urethane in linear phenoxy resins. Phenoxy vitrimers are obtained by a two-steps synthesis from a commercial phenoxy resin via partial conversion of hydroxyl groups to acetoacetates (AcAc), followed by network formation by reaction with m-xylylendiamine (XYDIA) as crosslinker. Three different vitrimers with variable crosslinking density are obtained by tuning the density of AcAc moieties along the phenoxy resin scaffold (5%, 10% and 15% conversion of hydroxyl groups). The conversion of linear polymers to dynamic crosslinked networks is confirmed by Dynamic Mechanical Thermal Analyzer (DMTA) and rheology measurements, followed by stress relaxation tests to investigate the kinetics of bond exchanges. Tensile tests as a function of reprocessing cycles reveal an increase of the maximum elongation and stress at break and prove the good recyclability of the vitrimers. Enhanced adhesive properties compared to pristine phenoxy resins are demonstrated, including the possibility to thermally re-join the assembly after its mechanical failure. Finally, the solvent-free preparation of vitrimer is explored for 5% crosslinked vitrimer via melt reactive blending, providing a valuable alternative to the less environmentally sustainable synthesis in solution

Encapsulation of trimethine cyanine in cucurbit[8]uril: solution versus solid-state inclusion behavior

Inclusion of polymethine cyanine dyes in the cavity of macrocyclic receptors is an effective strategy to alter their absorption and emission behavior in aqueous solution. In this paper, the effect of the host-guest interaction between cucurbit[8]uril (CB[8]) and a model trimethine indocyanine (Cy3) on dye spectral properties and aggregation in water is investigated. Solution studies, performed by a combination of spectroscopic and calorimetric techniques, indicate that the addition of CB[8] disrupts Cy3 aggregates leading to the formation of a 1:1 host-guest complex with an association constant of 1.5 × 10 6 M -1 . At concentrations suitable for NMR experiments, the slow formation of a supramolecular polymer was observed, followed by precipitation. Single crystals X-ray structure elucidation confirmed the formation of a polymer with 1:1 stoichiometry in the solid state

Hand Hygiene and Glove Use Behavior in an Italian Hospital

In an Italian hospital, we observed that hand hygiene was performed in 638 (19.6%) of 3,253 opportunities, whereas gloves were worn in 538 (44.2%) 1,218 of opportunities. We observed an inverse correlation between the intensity of care and the rate of hand hygiene compliance (R2=0.057; P<.001), but no such association was observed for the rate of glove use compliance (R2 = 0.014; P = .078). Rates of compliance with hand hygiene and glove use recommendations follow different behavioral pattern

Ultrafast all-optical second harmonic wavefront shaping

Optical communication can be revolutionized by encoding data into the orbital angular momentum of light beams. However, state-of-the-art approaches for dynamic control of complex optical wavefronts are mainly based on liquid crystal spatial light modulators or miniaturized mirrors, which suffer from intrinsically slow (mu s-ms) response times. Here, we experimentally realize a hybrid meta-optical system that enables complex control of the wavefront of light with pulse-duration limited dynamics. Specifically, by combining ultrafast polarization switching in a WSe2 monolayer with a dielectric metasurface, we demonstrate second harmonic beam deflection and structuring of orbital angular momentum on the femtosecond timescale. Our results pave the way to robust encoding of information for free space optical links, while reaching response times compatible with real-world telecom applications.Enhancing the data encoding into the orbital angular momentum of light beams could enable faster and more efficient optical communications. This work demonstrates complex control of the second harmonic wavefront with dynamics solely limited by the pulse duration

Photocatalytic activity of exfoliated graphite-TiO2_2 nanocomposites

We investigate the photocatalytic performance of composites prepared in a one-step process by liquid-phase exfoliation of graphite in the presence of TiO2 nanoparticles (NPs) at atmospheric pressure and in water, without heating or adding any surfactant, and starting from low-cost commercial reagents. These show enhanced photocatalytic activity, degrading up to 40% more pollutants with respect to the starting TiO2-NPs, in the case of a model dye target, and up to 70% more pollutants in the case of nitrogen oxides. In order to understand the photo-physical mechanisms underlying this enhancement, we investigate the photo-generation of reactive species (trapped holes and electrons) by ultrafast transient absorption spectroscopy. We observe an electron transfer process from TiO2 to the graphite flakes within the first picoseconds of the relaxation dynamics, which causes the decrease of the charge recombination rate, and increases the efficiency of the reactive species photo-production.We acknowledge funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 785219 (GrapheneCore2), EU Neurofibres, ERC Minegrace and Hetero2D, EPSRC Grants EP/509K01711X/1, EP/K017144/1, EP/N010345/1, EP/M507799/5101, and EP/L016087/1

Identity and Modality in OntoClean

The aim of this paper is to refine, integrate and apply the methodology of OntoClean. Three aspects are taken into account; two of them concern main ideas of OntoClean, the third one is a study of a particular important application. The first section deals with the topic of identity: formal constraints on identity criteria, compatibility and identity among identity criteria. The second section deals with rigidity, dependence and existence. The final section investigates how meta-property criteria can be applied to the notion of artifact

Hand hygiene and glove use behavior in an Italian hospital

In an Italian hospital, we observed that hand hygiene was performed in 638 (19.6%) of 3,253 opportunities, whereas gloves were worn in 538 (44.2%) 1,218 of opportunities. We observed an inverse correlation between the intensity of care and the rate of hand hygiene compliance (R2=0.057; P<.001), but no such association was observed for the rate of glove use compliance (R2=0.014; P=.078). Rates of compliance with hand hygiene and glove use recommendations follow different behavioral patterns