RESUMEN
Herein, we introduce a photobiocidal surface activated by white light. The photobiocidal surface was produced through thermocompressing a mixture of titanium dioxide (TiO2), ultra-high-molecular-weight polyethylene (UHMWPE), and reduced graphene oxide (rGO) powders. A photobiocidal activity was not observed on UHMWPE-TiO2. However, UHMWPE-TiO2@rGO exhibited potent photobiocidal activity (>3-log reduction) against Staphylococcus epidermidis and Escherichia coli bacteria after a 12 h exposure to white light. The activity was even more potent against the phage phi 6 virus, a SARS-CoV-2 surrogate, with a >5-log reduction after 6 h exposure to white light. Our mechanistic studies showed that the UHMWPE-TiO2@rGO was activated only by UV light, which accounts for 0.31% of the light emitted by the white LED lamp, producing reactive oxygen species that are lethal to microbes. This indicates that adding rGO to UHMWPE-TiO2 triggered intense photobiocidal activity even at shallow UV flux levels.
Asunto(s)
Escherichia coli , Grafito , Luz , Polietilenos , Staphylococcus epidermidis , Titanio , Grafito/química , Grafito/farmacología , Grafito/efectos de la radiación , Titanio/química , Titanio/farmacología , Polietilenos/química , Polietilenos/efectos de la radiación , Polietilenos/farmacología , Staphylococcus epidermidis/efectos de los fármacos , Escherichia coli/efectos de los fármacos , Antibacterianos/farmacología , Antibacterianos/química , Especies Reactivas de Oxígeno/metabolismo , Rayos UltravioletaRESUMEN
Precursor design is the crucial step in tailoring the deposition profile towards a multitude of functional materials. Most commercially available aluminium oxide precursors require high processing temperatures (>500 °C). Herein, we report the tuning of the decomposition profile (200-350 °C) of a range of octahedrally coordinated tris(ß-ketoiminate) aluminium complexes of the type [Al(MeCN(R)CHC=OMe)3 ], by varying the R substituents in the ligands. The complexes are derived from the reaction of trimethylamine alane (TMAA) and a series of N-substituted ß-ketoiminate ligands (R-acnacH, R=Me, Et, i Pr, Ph) with varying R-substituents sizes. When the more sterically encumbered ligand (R=Mes) was used, the Al atom became five-coordinate, therefore representing the threshold to octahedral coordination around the metal in these type of compounds, which, consequently, lead to a change of decomposition profile. The resulting compounds have been characterised by NMR spectroscopy, mass spectrometry, elemental analysis and single crystal X-ray diffraction. [Al(MeCN(Me)CHC=OMe)3 ] has been used as a single source precursor for the deposition of Al2 O3 . Thin films were deposited via aerosol assisted chemical vapour deposition (AACVD), with toluene as the solvent, and were analysed using SEM, EDX and XPS.
RESUMEN
The sudden irruption of COVID-19 has paralysed, even devastated, numerous industries. Academic and industry publications also convey the destructive impacts of this phenomenon on hospitality and tourism businesses. While business owners and managers are still constrained by unpredictability, restrictions, and ongoing uncertainty, those vying to continue will need to build their adaptive skill repertoire to cope with the crisis-related regime. This study is primarily concerned with businesses' adaptation phase from owners/managers' viewpoints, including how they manage and envision a future coexistence with COVID-19 threats. Drawing on an international sample of owners/managers of hospitality and tourism businesses, and considering the foundations of the dynamic capabilities framework, eight dimensions emerged from the findings. Five of these, persevering, dynamic, austere restrictions, business environment, and stakeholder, strongly suggest the relevance of reconfiguring, a cluster of dynamic capabilities. Together, the dimensions demonstrate participants' strong commitment to navigate through the threat while pursuing socioeconomic sustainability.
RESUMEN
Drawing on the theory of resilience, and on an international sample of 45 predominantly small hospitality businesses, this exploratory study extends knowledge about the key concerns, ways of coping, and the changes and adjustments undertaken by these firms' owners and managers during the COVID-19 outbreak. The various emergent relationships between the findings and the considered conceptual underpinnings of the literature on resilience, revealed nine theoretical dimensions. These dimensions critically illuminate and extend understanding concerning the actions and alternatives owners-managers resorted to when confronted with an extreme context. For instance, with financial impacts and uncertainty being predominant issues among participants, over one-third indicated actioning alternative measures to create much-needed revenue streams, and preparing for a new post-COVID-19 operational regime, respectively. Furthermore, 60 percent recognised making changes to the day-to-day running of the business to respond to initial impacts, or biding time in anticipation of a changing business and legal environment.