RESUMO
BACKGROUND: To prevent occupational skin diseases, employees are instructed to periodically apply hand protection products as a barrier to protect their hands from water, cleaning agents or other irritants. The aim of this work was to investigate whether bacteria present on the skin at the time of protection product application are enclosed underneath this protective layer, if they can be transferred to other surfaces and if a standard isopropanol-based skin disinfectant can nonetheless reduce the bacterial burden. METHODS: This prospective study was conducted in human volunteers based on the European Standard (EN 1500) to assess the burden of microorganisms before and after the application of various protection product formulations and subsequent hand disinfection. RESULTS: All protection products, with the exception of alcohol-based gels, enclosed bacteria underneath a lipid layer which could be transferred onto other surfaces. Still, the hand disinfectant efficiently reduced the bacteria burden. DISCUSSION: In occupations where proper hand hygiene is vital, alcohol-based gels might be the best option for the protection of the skin barrier as well as for reducing the contamination risk. CONCLUSION: An alcohol-based disinfection agent can dissolve the lipid film of protection products following the standard protocol for hygienic hand disinfection.
RESUMO
Metal-organic frameworks (MOFs) can serve as precursors for new nanomaterials via thermal decomposition. Such MOF-derived nanomaterials (MDNs) are often comprised of metal and/or metal oxide particles embedded on porous carbon. The morphology of MDNs is similar to that of the precursor MOF, and improved stability and catalytic properties have been demonstrated. However, the pathway from MOF to MDN is only well understood for a few systems, and in situ studies are needed to elucidate the full phase behaviour and time/temperature dependency. In this work, we follow the MOF-to-MDN transformation in situ by using three complementary techniques: X-ray absorption spectroscopy (XAS), powder X-ray diffraction (PXRD), and X-ray total scattering/pair distribution function (TS/PDF) analysis. The thermal decomposition of HKUST-1, i.e. the archetypical MOF Cu3(btc = 1,3,5-benzenetricarboxylate)2, is followed from room temperature to 500 °C by applying different heating ramps. Real space correlations are followed by PDF and extended X-ray absorption fine structure (EXAFS) analysis, and quantitative phase fractions are obtained by refinement of PXRD and PDF data, and by linear combination analysis (LCA) of X-ray absorption near edge Structure (XANES) data. We find that HKUST-1 decomposes at 300-325 °C into copper(I) oxide and metallic copper. Above 350-470 °C, metal particles remain as the only copper species. There is an overall good agreement between all three techniques with respect to the phase evolution, and the study paves the road towards rational synthesis of a Cu2O/Cu/carbon material with the desired metal/metal oxide composition. More importantly, our investigations serve as a benchmark study demonstrating that this methodology is generally applicable for studying the thermal decomposition of MOFs.