127 results on '"N. Widmer"'
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2. Thermal Behavior of Iron Arsenides Under Non-Oxidizing Conditions
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Ainur Seitkan, Giulio I. Lampronti, Remo N. Widmer, Nicola P. M. Casati, and Simon A. T. Redfern
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Chemistry ,QD1-999 - Published
- 2020
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3. Temperature–dependent dynamic plasticity of micro-scale fused silica
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Remo N. Widmer, Alexander Groetsch, Guillaume Kermouche, Ana Diaz, Gilles Pillonel, Manish Jain, Rajaprakash Ramachandramoorthy, Laszlo Pethö, Jakob Schwiedrzik, and Johann Michler
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Fused silica ,Micro-mechanics ,Plasticity ,High temperature ,High strain rate ,X-ray ptychographic tomography ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
The ability to predict the micro-scale strength and plasticity of fused-silica micro-components is crucial as their miniaturization and applications in harsh environments advance. This study focusses on the micro-mechanical behavior of fused silica micropillars at high temperatures and variable strain rates. 160 micropillars with a diameter of 1.6 µm have been tested at temperatures between −120 °C and 600 °C and strain rates between 10-3 s−1 and 1 s−1, which are to date unexplored conditions. Between −120 °C and 300 °C, the yield strengths (6–8 GPa) and strain rate sensitivities (≤0.03) vary only marginally. However, at 600 °C, a significant decrease in yield strength by more than 50 % (2.5–4.5 GPa) and an increase in strain rate sensitivity by a factor of 3 (0.09) is observed. Post-compression synchrotron-based ptychographic X-ray computed tomography (PXCT) on plastically deformed micropillars revealed a transition in deformation mechanisms: Shear-localization and shear-promoted densification at 25 °C; homogeneous shear-flow and densification limited by radial cracking at 300 °C; and unconstrained shear-flow and limited densification due to weak confinement strength at 600 °C. FEM results support these observations while separating geometric from material-intrinsic effects. These results suggest that the classification of fused silica as a glass that deforms predominantly through densification should be challenged – at least under unconstrained compression, which is the predominant mode of loading in applications.
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- 2022
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4. Smooth or not: Robust fused silica micro-components by femtosecond-laser-assisted etching
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Remo N. Widmer, David Bischof, Jakub Jurczyk, Markus Michler, Jakob Schwiedrzik, and Johann Michler
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Fused Silica ,Femtosecond Laser ,Chemical Etching ,Micromechanics ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Recent progress in manufacturing now enables the efficient fabrication of complex oxide-glass components at the micrometer– to sub-micrometer scale. This benefits both the industry and fundamental research as such miniature glass parts have numerous applications. However, at these length-scales, the mechanical properties of glasses can no longer be predicted based on bulk material characteristics. Here it is shown that fused silica micro-pillars fabricated by laser-assisted etching are almost ten times stronger than their bulk-sized counterparts. The relatively rough surface typical for this process does not much impair this strength. Additionally, it is demonstrated that annealing of the as-fabricated structures at 1200 °C in air results in significantly smoother surfaces. The accompanying increase in mechanical strength from approximately 8 GPa to 10 GPa is due to the reduction of stress concentrations at the surface, as demonstrated by finite element simulations. It is also demonstrated that the gain in mechanical resistance of glass components due to downsizing occurs already for parts as large as almost 20 µm – orders of magnitude above the critical size reported for other micro-mechanical effects. These micro-mechanical properties of selective laser-assisted etching structured fused silica components are key to a reliable use of glass micro-components.
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- 2021
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5. Mechanical Properties of Atomic-Layer-Deposited Al2O3/Y2O3 Nanolaminate Films on Aluminum toward Protective Coatings
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Janne-Petteri Niemelä, Barbara Putz, Gustavo Mata-Osoro, Carlos Guerra-Nuñez, Remo N. Widmer, Nadia Rohbeck, Thomas E. J. Edwards, Max Döbeli, Krzysztof Maćkosz, Aleksandra Szkudlarek, Yury Kuzminykh, Xavier Maeder, Johann Michler, Bernhard Andreaus, and Ivo Utke
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General Materials Science - Published
- 2022
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6. Plasticity of Metal–Organic Framework Glasses
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Manish Jain, Remo N. Widmer, Johann Michler, Alice M. Bumstead, and Thomas D. Bennett
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Structural material ,Strain (chemistry) ,Chemistry ,02 engineering and technology ,General Chemistry ,Plasticity ,Strain rate ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Compression (physics) ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Colloid and Surface Chemistry ,Brittleness ,Molecule ,Composite material ,0210 nano-technology ,Material properties - Abstract
Metal-organic framework (MOF) glasses provide new perspectives on many material properties due to their unique chemical and structural nature. Their mechanical properties are of particular interest because glasses are inherently brittle, which limits their applications as structural materials. Here we perform strain-rate-dependent uniaxial micropillar compression experiments on agZIF-62, agZIF-UC-5, and agTIF-4, a series of MOF glasses with different substituting linker molecules, and find that these glasses show substantial plasticity, at least on the micrometer scale. At a quasi-static strain rate of 0.001 s-1, the micropillars yielded at approximately 0.32 GPa and subsequently deformed plastically up to 35% strain, irrespective of the type of substituting linker. With increasing strain rate, the yield strength of agZIF-62 evolved with the strain-rate sensitivity m = 0.024 to reach a yield strength of 0.44 GPa at a strain rate of 510 s-1. On the basis of this relatively low strain-rate sensitivity and the absence of serrated flow, we conclude that structural densification is the predominant mechanism that accommodates such extensive plasticity.
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- 2021
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7. Combinatorial Study of Phase Composition, Microstructure and Mechanical Behavior of Co-Cr-Fe-Ni Nanocrystalline Film Processed by Multiple-Beam-Sputtering Physical Vapor Deposition
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Péter Nagy, Nadia Rohbeck, Remo N. Widmer, Zoltán Hegedűs, Johann Michler, László Pethö, János L. Lábár, and Jenő Gubicza
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multiple-beam-sputtering physical vapor deposition ,compositional complex alloy ,microstructure ,hardness ,elastic modulus ,General Materials Science ,ddc:600 - Abstract
Materials 15(6), 2319 (2022). doi:10.3390/ma15062319, A combinatorial Co-Cr-Fe-Ni compositional complex alloy (CCA) thin film disk with a thickness of 1 µm and a diameter of 10 cm was processed by multiple-beam-sputtering physical vapor deposition (PVD) using four pure metal sources. The chemical composition of the four constituent elements varied between 4 and 64 at.% in the film, depending on the distance from the four PVD sources. The crystal structure, the crystallite size, the density of lattice defects (e.g., dislocations and twin faults) and the crystallographic texture were studied as a function of the chemical composition. It was found that in a wide range of elemental concentrations a face-centered cubic (fcc) structure with {111} crystallographic texture formed during PVD. Considering the equilibrium phase diagrams, it can be concluded that mostly the phase composition of the PVD layer is far from the equilibrium. Body-centered cubic (bcc) and hexagonal-close packed (hcp) structures formed only in the parts of the film close to Co-Fe and Co-Cr sources, respectively. A nanocrystalline microstructure with the grain size of 10–20 nm was developed in the whole layer, irrespective of the chemical composition. Transmission electron microscopy indicated a columnar growth of the film during PVD. The density of as-grown dislocations and twin faults was very high, as obtained by synchrotron X-ray diffraction peak profile analysis. The nanohardness and the elastic modulus were determined by indentation for the different chemical compositions on the combinatorial PVD film. This study is the continuation of a former research published recently in Nagy et al., Materials 14 (2021) 3357. In the previous work, only the fcc part of the sample was investigated. In the present paper, the study was extended to the bcc, hcp and multiphase regions., Published by MDPI, Basel
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- 2022
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8. Synthesis and Properties of a Compositional Series of MIL-53(Al) Metal–Organic Framework Crystal-Glass Composites
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Duncan N. Johnstone, Christopher W. Ashling, David A. Keen, Jingwei Hou, Remo N. Widmer, Sean M. Collins, Paul A. Midgley, Adam F. Sapnik, Thomas D. Bennett, Philip A. Chater, and Alice M. Bumstead
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Nanostructure ,Materials science ,Chemical substance ,Chemistry ,Composite number ,Pair distribution function ,Sorption ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Article ,Catalysis ,0104 chemical sciences ,Adsorption ,Colloid and Surface Chemistry ,Lead glass ,visual_art ,Scanning transmission electron microscopy ,visual_art.visual_art_medium ,Metal-organic framework ,Composite material ,Science, technology and society - Abstract
Metal–organic framework crystal-glass composites (MOF-CGCs) are materials in which a crystalline MOF is dispersed within a MOF glass. In this work, we explore the room-temperature stabilization of the open-pore form of MIL-53(Al), usually observed at high temperature, which occurs upon encapsulation within a ZIF-62(Zn) MOF glass matrix. A series of MOF-CGCs containing different loadings of MIL-53(Al) were synthesized and characterized using X-ray diffraction and nuclear magnetic resonance spectroscopy. An upper limit of MIL-53(Al) that can be stabilized in the composite was determined for the first time. The nanostructure of the composites was probed using pair distribution function analysis and scanning transmission electron microscopy. Notably, the distribution and integrity of the crystalline component in a sample series were determined, and these findings were related to the MOF-CGC gas adsorption capacity in order to identify the optimal loading necessary for maximum CO2 sorption capacity.
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- 2019
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9. The effect of activation time on water sorption behavior of nitrogen-doped, physically activated, monolithic carbon for adsorption cooling
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Stefanie Beatrice Hauser, Matthias M. Koebel, Yucheng Zhang, Lukas Huber, Roland Hauert, Jens Ammann, Songhak Yoon, Santhosh Kumar Matam, Christopher Ubert, Patrick Ruch, Remo N. Widmer, and Eric Brendlé
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Materials science ,Silica gel ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Water sorption ,Microporous material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,Adsorption ,Chemical engineering ,Volume (thermodynamics) ,chemistry ,Mechanics of Materials ,law ,Specific surface area ,General Materials Science ,0210 nano-technology ,Carbon ,Heat pump - Abstract
Monolithic, nitrogen-doped carbon sorbents were prepared from resorcinol-urea-formaldehyde resins and physically activated with CO2 for different activation times. The effect of the activation time on the water sorption behavior and the physicochemical properties were investigated. Longer activation times lead to a steeper slope of the water sorption isotherm and, due to a higher specific surface area and micropore volume, an increased water sorption capacity. It was found that, after physical activation for 3 h at 800 °C, the physically activated, nitrogen-doped carbon has a high surface area (>1000 m2/g) and a high water sorption capacity (50 wt%). In a miniaturized adsorption heat pump test stand, the best candidate material was assessed alongside commercial silica gel for reference. At a temperature swing from 90 °C → 50 °C, the CO2-activated carbon exhibits a maximal specific cooling power which is a factor of 1.7 higher in comparison with the reference silica gel (429 W/kg versus 255 W/kg). At a more applicable temperature swing, 60 °C → 30 °C, the CO2-activated carbon yields a specific cooling power 3.8 times higher than that of the silica gel reference (932 W/kg versus 240 W/kg).
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- 2019
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10. Deep carbon cycle constrained by carbonate solubility
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Mohamed Mezouar, Stefan Farsang, Remo N. Widmer, Simon A. T. Redfern, Angelika Dorothea Rosa, Xiaolei Feng, Chaoshuai Zhao, Jin Liu, Marion Louvel, Farsang, Stefan [0000-0002-4918-5566], Mezouar, Mohamed [0000-0001-5336-544X], Rosa, Angelika D [0000-0002-2304-1943], Widmer, Remo N [0000-0001-7664-4791], Feng, Xiaolei [0000-0003-4410-4576], Liu, Jin [0000-0002-1670-8199], Redfern, Simon AT [0000-0001-9513-0147], Apollo - University of Cambridge Repository, Redfern, Simon A T [0000-0001-9513-0147], Department of Earth Sciences, University of Cambridge, University of Cambridge [UK] (CAM), Institut für Mineralogie-Münster, Westfälische Wilhelms-Universität Münster (WWU), Center for High Pressure Science & Technology Advanced Research (HPSTAR), European Synchrotron Radiation Facility (ESRF), Swiss Federal Laboratories for Materials Science and Technology (EMPA), Asian School of the Environment (ASE), Nanyang Technological University [Singapour], Rosa, Angelika D. [0000-0002-2304-1943], Widmer, Remo N. [0000-0001-7664-4791], and Redfern, Simon A. T. [0000-0001-9513-0147]
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Rhodochrosite ,010504 meteorology & atmospheric sciences ,Science ,General Physics and Astronomy ,Mineralogy ,chemistry.chemical_element ,010502 geochemistry & geophysics ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Article ,Carbon cycle ,chemistry.chemical_compound ,[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry ,Solubility ,Dissolution ,0105 earth and related environmental sciences ,13 Climate Action ,Multidisciplinary ,General Chemistry ,704/2151/330 ,Geochemistry ,chemistry ,13. Climate action ,Slab ,Carbonate ,704/2151/209 ,Carbon ,Magnesite - Abstract
Earth’s deep carbon cycle affects atmospheric CO2, climate, and habitability. Owing to the extreme solubility of CaCO3, aqueous fluids released from the subducting slab could extract all carbon from the slab. However, recycling efficiency is estimated at only around 40%. Data from carbonate inclusions, petrology, and Mg isotope systematics indicate Ca2+ in carbonates is replaced by Mg2+ and other cations during subduction. Here we determined the solubility of dolomite [CaMg(CO3)2] and rhodochrosite (MnCO3), and put an upper limit on that of magnesite (MgCO3) under subduction zone conditions. Solubility decreases at least two orders of magnitude as carbonates become Mg-rich. This decreased solubility, coupled with heterogeneity of carbon and water subduction, may explain discrepancies in carbon recycling estimates. Over a range of slab settings, we find aqueous dissolution responsible for mobilizing 10 to 92% of slab carbon. Globally, aqueous fluids mobilise \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${35}_{-17}^{+20}$$\end{document}35−17+20% (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${27}_{-13}^{+16}$$\end{document}27−13+16 Mt/yr) of subducted carbon from subducting slabs., Carbonate mineral aqueous solubility decreases as carbonates become more Mg-rich during subduction. Coupled with regional variations in amounts of carbon and water subducted, this explains discrepancies in estimates of carbon recycling, suggesting that only around a third returns to the surface.
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- 2021
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11. Singlet Fission in Concentrated TIPS-Pentacene Solutions: The Role of Excimers and Aggregates
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Miroslav Dvořák, Shyamal Prasad, Cameron Dover, Chelsea Forest, Akasha Kaleem, Rowan W. MacQueen, Anthony J Petty, Roslyn Forecast, John E. Anthony, Murad J. Y. Tayebjee, Asaph N. Widmer-Cooper, Pall Thordarson, and Timothy Schmidt
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The exciton dynamics of 6,13-bis(triisopropylsilyl-ethynyl) pentacene is investigated to determine the role of excimer and aggregate formation in singlet fission in high concentration solutions.Photoluminescence spectra were measured by excitation with the evanescent wave in total internal reflection, in order to avoid reabsorption effects. The spectra over nearly two magnitudes of concentration were near identical, with no evidence for excimer emission. Time-correlated single-photon counting measurements confirm that the fluorescence lifetime shortens with concentration, and we obtain a bimolecular rate constant of $4\times10^9$\,M$^{-1}$s$^{-1}$ in chloroform. The observed rate constant grows at high concentrations. This effect is modelled in terms of the hard sphere radial distribution function.NMR measurements confirm that aggregation takes place with a binding constant of between 0.14 and 0.43M$^{-1}$. Transient absorption measurements are consistent with a diffusive encounter mechanism for singlet fission, with hints of more rapid singlet fission in aggregates at the highest concentration measured.These data show that excimers do not play the role of an emissive intermediate in exothermic singlet fission in solution, and that while aggregation occurs at higher concentrations, the mechanism of singlet fission remains dominated by diffusive encounters.
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- 2021
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12. Effect of salinity, pressure and temperature on the solubility of smithsonite (ZnCO3) and Zn complexation in crustal and upper mantle hydrothermal fluids
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Remo N. Widmer, Stefan Farsang, Marion Louvel, Monica Amboage, Angelika Dorothea Rosa, Simon A. T. Redfern, Simone Anzellini, Redfern, Simon [0000-0001-9513-0147], and Apollo - University of Cambridge Repository
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Smithsonite ,Salinity ,010504 meteorology & atmospheric sciences ,Absorption spectroscopy ,XAS ,Analytical chemistry ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Diamond anvil cell ,Hydrothermal circulation ,Geochemistry and Petrology ,DAC ,Solubility ,0105 earth and related environmental sciences ,X-ray absorption spectroscopy ,Aqueous solution ,Subduction zone fluids ,Geology ,High temperature ,Synchrotron XRF ,High pressure ,Zinc speciation ,engineering ,Deep Earth - Abstract
Modelling the reservoirs and fluxes of Zn in Earth's crust and mantle requires data on the solubility of its mineral hosts and ores in coexisting fluids, as well as on the complexation of Zn in these fluids as a function of fluid composition, pressure, and temperature. However, due to experimental challenges, the availability of such data is limited to pressures below 1 GPa, which are only representative of upper crust conditions. Here, we report the effects of salinity (0–4.5 m total Cl), pressure (0.5–6 GPa) and temperature (25–400 °C) on the solubility of smithsonite (ZnCO3) and speciation of Zn in aqueous fluids. Solubilities at mineral-fluid equilibria and Zn speciation in the coexisting aqueous fluids were determined in situ at high pressure-temperature (P-T) conditions by synchrotron X-ray fluorescence (XRF) and X-ray absorption spectroscopy (XAS) using resistively heated diamond anvil cells (RH-DAC). The solubility of smithsonite increases with salinity, pressure, and temperature. In agreement with previous studies, conducted at lower pressures (below 1 GPa), we observed a gradual transition from octahedral hydrated [Zn(H2O)6]2+ to tetrahedral hydrated and chlorinated [Zn(H2O)4-nCln]2-n (n = 1–4) complexes with increasing salinity and temperature. Our results suggest that these tetrahedral complexes remain stable under the conditions relevant to cold slab dehydration. This change of coordination further enhances the solubility of smithsonite in Cl-rich fluids and provides a likely mechanism for the efficient uptake of Zn by slab-derived fluids.
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- 2021
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13. First natural hexaferrite with mixed β‴-ferrite (β-alumina) and magnetoplumbite structure from Jabel Harmun, Palestinian Autonomy
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Remo N. Widmer, Evgeny V. Galuskin, Irina O. Galuskina, and Thomas Armbruster
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Crystallography ,symbols.namesake ,Materials science ,Geochemistry and Petrology ,0502 economics and business ,05 social sciences ,symbols ,Ferrite (magnet) ,050211 marketing ,010502 geochemistry & geophysics ,Raman spectroscopy ,01 natural sciences ,0105 earth and related environmental sciences - Published
- 2018
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14. COMPARISON BETWEEN SINGLE EARLY-LOADED IMPLANTS WITH SANDBLASTED ACIDETCHED (SA) SURFACE VERSUS SA SURFACE MODIFIED WITH PH BUFFERING AGENT (SOI): FOUR-MONTH DATA FROM A SPLIT-MOUTH, MULTICENTRE RANDOMIZED CONTROLLED TRIAL
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L. Zadrożny, E. Xhanari, M. Gheorghita, A. De Waal, N. Widmer, L. Muzzi, E. Deliverska, F. Gatti, M. Czajkowska, J. Buti, A. Alushi, and M. Tallarico
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- 2022
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15. Manufacturing Macroporous Monoliths of Microporous Metal–Organic Frameworks
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Giulio I. Lampronti, Benjamin Kunz, Corsin Battaglia, Remo N. Widmer, Simon A. T. Redfern, Thomas D. Bennett, and Jennifer H. Shepherd
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Materials science ,Chemical engineering ,010405 organic chemistry ,Sintering ,General Materials Science ,Metal-organic framework ,Microporous material ,010402 general chemistry ,Porosity ,01 natural sciences ,0104 chemical sciences ,Zeolitic imidazolate framework ,Characterization (materials science) - Abstract
We report the first use of a pressure-assisted sintering technique on metal–organic framework powders, allowing for the fast production of crystalline macroporous monoliths. Mechanical and microstructural characterization of the monoliths is presented. The interconnected macroporosity of the compacts can be adjusted, providing an immense interface for gas–solid interaction. The sintering technique is well-established and commercially available, allowing industrial scale-up of the process.
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- 2018
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16. Khesinite, Ca4Mg2Fe3+ 10O4[(Fe3+ 10Si2)O36], a new rhönite-group (sapphirine supergroup) mineral from the Negev Desert, Israel– natural analogue of the SFCA phase
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Remo N. Widmer, Edward S. Grew, Evgeny V. Galuskin, Thomas Armbruster, Irina O. Galuskina, Mikhail N. Murashko, Yevgeny Vapnik, Biljana Krüger, Piotr Dzierażanowski, and Anna S. Pakhomova
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Baryte ,010504 meteorology & atmospheric sciences ,Hornfels ,Mineralogy ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Cuspidine ,Magnesioferrite ,Sapphirine ,Crystallography ,Kalsilite ,Geochemistry and Petrology ,engineering ,Gehlenite ,Pseudowollastonite ,Geology ,0105 earth and related environmental sciences - Abstract
Khesinite, Ca 4 Mg 2 Fe 3+ 10 O 4 (Fe 3+ 10 Si 2 )O 36 , is a new member of the rhonite group of the sapphirine supergroup. Khesinite was discovered in thin veins of paralavas within fine-grained gehlenite rocks (hornfels) of the Hatrurim Complex in the Negev Desert, Israel. Paralavas are composed of rankinite, pseudowollastonite (rarely wollastonite), flamite, kalsilite, cuspidine and members of the solid-solution series: schorlomite–andradite, gehlenite–ackermanite–“Fe 3+ -gehlenite”, magnesioferrite–spinel and fluorapatite–fluorellestadite. Accessory and rare minerals are represented by baryte, walstromite, fresnoite, vorlanite, barioferrite, hematite, perovskite, gurimite, zadovite, aradite and hexacelsian. Electron-microprobe analysis of the holotype khesinite gives the following empirical formula for 40 oxygens and 28 cations: Ca 4 (Fe 3+ 8.528 Mg 1.635 Ca 0.898 Ti 4+ 0.336 Ni 2+ 0.217 Mn 2+ 0.155 Cr 3+ 0.132 Fe 2+ 0.098 ) Σ12 [(Fe 3+ 6.827 Al 2.506 Si 2.667 ) Σ12 O 40 ]. Khesinite is black to dark brown. It has semi-metallic lustre and does not show fluorescence. Cleavage and parting are not observed, fracture is irregular. Khesinite has a Mohs9 hardness of 6; microhardness VHN 50 is 943 kg mm −2 . The calculated density is 4.097 g cm −3 . In reflected light khesinite is grey with weak internal brown reflections. Reflectance data for the COM (Commission of Ore Mineralogy, IMA) wavelengths vary from ~13.4% (470 nm) to ~11.8% (700 nm). The crystal structure of khesinite [ P 1 ¯ a = 10 . 5363 ( 1 ) , b = 10.9242(2), c = 9.0612(1) A, α = 106.340(1)°, β = 95.765(1)°, γ = 124.373(1)°, V = 780.54(2) A 3 ] was refined from X-ray single-crystal data to R 1 = 0.046. The khesinite structure is close to that of the synthetic compounds SFCA and SFCAM. Khesinite crystallized in paralava from melt, sometimes forming isolated crystals, but more commonly reaction rims on magnesioferrite in association with pseudowollastonite and flamite at temperature not lower than 1200 °C.
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- 2017
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17. Thermal Behavior of Iron Arsenides Under Non-Oxidizing Conditions
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Nicola Casati, Giulio I. Lampronti, Simon A. T. Redfern, Ainur Seitkan, Remo N. Widmer, Seitkan, Ainur [0000-0001-9309-500X], Apollo - University of Cambridge Repository, Redfern, Simon [0000-0001-9513-0147], and Asian School of the Environment
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In situ ,Diffraction ,Materials science ,34 Chemical Sciences ,Iron ,General Chemical Engineering ,General Chemistry ,Geology [Science] ,sub-03 ,Synchrotron ,Article ,law.invention ,3402 Inorganic Chemistry ,Chemistry ,Neutral atmosphere ,Chemical engineering ,law ,Thermal ,Oxidizing agent ,Crystal Structure ,QD1-999 ,Powder diffraction ,Phase diagram - Abstract
Fe2As has been studied in situ by synchrotron powder X-ray diffraction (PXRD) over the range of temperatures 25–850 °C and under a neutral atmosphere to understand its thermal behavior, which is potentially important for gold extraction. For the first time, incongruent high-temperature reactions of Fe2As are observed as it breaks down and the existence of a previously undiscovered high-temperature FeAs phase with an NiAs-type structure has been determined experimentally. No evidence has been found for the existence of the high-temperature Fe3As2 phase. Hence, the previously published phase diagram for the Fe–As system has to be modified accordingly. Published version
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- 2019
18. X-ray radiation-induced amorphization of metal-organic frameworks
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Thomas D. Bennett, Remo N. Widmer, Stefan Farsang, Nicola Casati, Simon A. T. Redfern, and Giulio I. Lampronti
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Materials science ,X-ray ,Nucleation ,General Physics and Astronomy ,02 engineering and technology ,Radiation ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Synchrotron ,0104 chemical sciences ,law.invention ,Chemical physics ,law ,Phase (matter) ,Thermal stability ,Metal-organic framework ,Physical and Theoretical Chemistry ,0210 nano-technology ,Beam (structure) - Abstract
We report the amorphization of three metal-organic frameworks, ZIF-4, ZIF-62, and ZIF-zni, by synchrotron X-ray radiation. Complete amorphization of these structures occurs on timescales ranging from minutes to hours. This process is non-isokinetic in all three cases, given a varying transformation rate as the transformation proceeds. The underlying mechanism bears the signature of inhomogeneous nucleation, reflected by an increasing local Avrami exponent over time. Furthermore, the amorphization rate accelerates with increasing temperature, even far below the usual thermal stability limit of each crystalline phase. These results not only have important implications for interpretation of X-ray synchrotron studies on the stability of metal-organic frameworks, they also shed light on the rarely-discussed and generally unpredictable experimental problem of beam damage in organic and inorganic compounds in general.
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- 2019
19. Pressure promoted low-temperature melting of metal-organic frameworks
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Ana M. Belenguer, Giulio I. Lampronti, Hannah Palmer, Stefan Farsang, Romain Gaillac, Shane G. Telfer, Craig W. Wilson, Michael T. Wharmby, Thomas D. Bennett, François-Xavier Coudert, Simon A. T. Redfern, S. G. MacLeod, Xiao Yu, Annette K. Kleppe, Chao Zhou, Simone Anzellini, Remo N. Widmer, Seth M. Cohen, Air Liquide, Centre de Recherche Claude-Delorme, Paris-Saclay, France., Institut de Recherche de Chimie Paris (IRCP), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Ministère de la Culture (MC)
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Materials science ,Physics::Optics ,02 engineering and technology ,sub-03 ,010402 general chemistry ,01 natural sciences ,symbols.namesake ,[CHIM]Chemical Sciences ,General Materials Science ,Porosity ,Phase diagram ,Mechanical Engineering ,[CHIM.MATE]Chemical Sciences/Material chemistry ,General Chemistry ,Microporous material ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Amorphous solid ,[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry ,Chemical engineering ,Mechanics of Materials ,symbols ,Metal-organic framework ,0210 nano-technology ,Raman spectroscopy ,Zeolitic imidazolate framework ,Ambient pressure - Abstract
Metal–organic frameworks (MOFs) are microporous materials with huge potential for chemical processes. Structural collapse at high pressure, and transitions to liquid states at high temperature, have recently been observed in the zeolitic imidazolate framework (ZIF) family of MOFs. Here, we show that simultaneous high-pressure and high-temperature conditions result in complex behaviour in ZIF-62 and ZIF-4, with distinct high- and low-density amorphous phases occurring over different regions of the pressure–temperature phase diagram. In situ powder X-ray diffraction, Raman spectroscopy and optical microscopy reveal that the stability of the liquid MOF state expands substantially towards lower temperatures at intermediate, industrially achievable pressures and first-principles molecular dynamics show that softening of the framework coordination with pressure makes melting thermodynamically easier. Furthermore, the MOF glass formed by melt quenching the high-temperature liquid possesses permanent, accessible porosity. Our results thus imply a route to the synthesis of functional MOF glasses at low temperatures, avoiding decomposition on heating at ambient pressure. The simultaneous high-pressure and high-temperature phase diagram of two MOFs, ZIF-4 and ZIF-62, is mapped. Crystalline, pressure- and temperature-amorphous, and liquid states are found, while melting temperature is found to decrease with pressure.
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- 2019
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20. Wernerkrauseite, CaFe3+ 2Mn4+O6: the first nonstoichiometric post-spinel mineral, from Bellerberg volcano, Eifel, Germany
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Günter Blass, Remo N. Widmer, Evgeny V. Galuskin, Biljana Krüger, Irina O. Galuskina, and Hannes Krüger
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Chemistry ,Spinel ,02 engineering and technology ,engineering.material ,010502 geochemistry & geophysics ,021001 nanoscience & nanotechnology ,01 natural sciences ,Cuspidine ,Magnesioferrite ,Crystallography ,Geochemistry and Petrology ,engineering ,Pleochroism ,Gehlenite ,0210 nano-technology ,Jennite ,Powder diffraction ,0105 earth and related environmental sciences ,Solid solution - Abstract
Black prismatic crystals of the new mineral wernerkrauseite, ideally CaFe3+2Mn4+O6 [ Pnma , a = 9.0548(2), b = 2.8718(1), c = 10.9908(2) A; V = 285.80(1) A3, Z = 8/3], were found in altered xenoliths within alkaline basalts of the Bellerberg volcano, Eifel, Rhineland-Palatinate, Germany. Fluorellestadite, wadalite, andradite–schorlomite, perovskite, gehlenite, magnesioferrite, cuspidine, ettringite–thaumasite, hydrocalumite, jennite, katoite, and portlandite are the main associated minerals. Wernerkrauseite crystals up to 0.5 mm in size show strong submetallic lustre; the streak is black. Wernerkrauseite appears grey in reflected light. Pleochroism is very weak, bireflectance and anisotropy are weak. Reflectance data for the COM wavelengths vary from ~31 % (400 nm) to ~19 % (700 nm). The calculated density is 4.66 g/cm3, microhardness VHN25 is 154(5) kg/mm2. Wernerkrauseite is a Ca-deficient structural analogue of harmunite, CaFe2O4, and therefore is one of the four known minerals with post-spinel structures. The empirical chemical formula of the holotype wernerkrauseite is Ca0.994(Fe3+1.057Mn4+1.025 Mn3+0.878Mg0.030Al0.016)∑3.006O6. The end-member chemical formula can also be given on the basis of spinel stoichoimetry ( Z = 4): Ca2/3[Fe3+4/3Mn4+2/3]O4, which better reflects its non-stoichiometry. The crystal structure was determined using single-crystal X-ray diffraction ( R 1 = 0.0233 for 800 observed reflections [ I >2σ( I )]). The diffraction pattern shows evidence of short-range ordering of Ca-vacancies. The strongest diffraction lines of the calculated powder diffraction pattern are [ d hkl ( I )]: 2.646 (100), 2.450 (77), 2.748 (62), 4.527 (54), 4.698 (44), 1.818 (43), 2.425 (37), 1.778 (30). Raman spectra of wernerkrauseite were measured and analysed in comparison to the spectra of harmunite and marokite, CaMn2O4. Crystallisation of wernerkrauseite took place at temperatures below 850–900°C under high oxygen fugacity. Furthermore, Mn4+-bearing non-stoichiometric harmunite Ca0.862(Fe3+1.719 Mn4+0.265Ti4+0.012 Mg0.008)∑2.004O4 was found at the same locality, which suggests the existence of a continuous solid solution between wernerkrauseite, harmunite and Ca2/3Mn3+4/3Mn4+2/3O4, described by the formula Ca1−x/2(Fe3+, Mn3+)2−xMn4+xO4, with × ranging from 0 to 2/3.
- Published
- 2016
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21. Pressure Promoted Low-Temperature Melting of Metal-Organic Frameworks
- Author
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Simone Anzellini, Michael T. Wharmby, François-Xavier Coudert, Simon A. T. Redfern, Hannah Palmer, Annette K. Kleppe, S. G. MacLeod, Stefan Farsang, Remo N. Widmer, Tom Bennett, Romain Gaillac, GiulioI. Lampronti, Ana M. Belenguer, and Chao Zhou
- Subjects
symbols.namesake ,Materials science ,Chemical engineering ,fungi ,symbols ,Molecule ,Metal-organic framework ,Microporous material ,Raman spectroscopy ,Phase diagram ,Amorphous solid ,Zeolitic imidazolate framework ,Ambient pressure - Abstract
Metal-organic frameworks (MOFs) are microporous materials with huge potential as host structures for chemical processes, including retention, catalytic reaction, or separation of guest molecules. Structural collapse at high-pressure, and unusual behaviours at elevated temperatures, such as melting and transitions to liquid states, have recently been observed in the family. Here, we show that the effect of the application of simultaneous high-pressure and -temperature on a MOF can be understood in terms of silicate analogues, with crystalline, amorphous and liquid states occurring across the pressure - temperature phase diagram. The response of ZIF-62, the MOF on which we focus, to simultaneous pressure and temperature reveals a complex behaviour with distinct high- and low- density amorphous phases occurring over different regions of the pressure-temperature space. In-situ powder X-ray diffraction, Raman spectroscopy and optical microscopy reveal that the stability of the liquid MOF-state expands significantly towards lower temperatures at intermediate, industrially achievable pressures. Our results imply a novel route to the synthesis of functional MOF glasses at low temperatures, avoiding decomposition upon heating at ambient pressure.
- Published
- 2018
- Full Text
- View/download PDF
22. The crystal structure of flamite and its relation to Ca2 SiO4 polymorphs and nagelschmidtite
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Frank Gfeller, Irina O. Galuskina, Remo N. Widmer, Biljana Krüger, Evgeny V. Galuskin, and Thomas Armbruster
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Mineral ,Crystal structure ,chemistry.chemical_compound ,symbols.namesake ,Crystallography ,chemistry ,Geochemistry and Petrology ,Phase (matter) ,Calcium silicate ,symbols ,Isostructural ,Raman spectroscopy ,Crystal twinning ,Derivative (chemistry) - Abstract
The recently accepted new mineral flamite IMA No. 2013–122, (Ca,Na,K) 2 (Si,P)O 4 , found in the pyrometamorphic rocks of the Hatrurim Formation, Israel, was reported to crystallize in the hexagonal space group P 6 3 with unit-cell parameters a = 43.3726(18), c = 6.8270(4) A. A careful re-examination of single crystals from the type locality and holotype material, however, shows that flamite is better described by the formula Ca 8−x (Na,K) x (SiO 4 ) 4−x (PO 4 ) x and that it crystallizes in the space group Pnm 2 1 , a = 9.3845(6), b = 21.7310(14), c = 6.8346(4) A, V = 1393.81(15) A3, Z =4 and is isostructural with the known synthetic P-doped clinker phase Ca 15 □(SiO 4 ) 6 (PO 4 ) 2 . The structure is a derivative of the hexagonal high-temperature variety of dicalcium-silicate, α-C 2 S, and is characterized by a cyclic triplet of individuals rotated 120° around c , interpreted as symplectite-like transformation “twinning” derived from α-C 2 S. The composition of intergrown flamite lamellae is chemically variable concerning the degree of Na, K and P substitution. We present the structure of flamite and discuss its close relationship to nagelschmidtite, Ca 7 (SiO 4 ) 2 (PO 4 ) 2 , and the high-temperature polymorphs of C 2 S.
- Published
- 2015
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23. Structural and Crystal Chemical Investigation of Intermediate Phases in the System Ca2 SiO4 - Ca3 (PO4 )2 -CaNaPO4
- Author
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Frank Gfeller, Thomas Armbruster, and Remo N. Widmer
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Crystal ,Crystallography ,Chemistry ,Phase (matter) ,Materials Chemistry ,Ceramics and Composites ,Supercell (crystal) ,Electron microprobe ,Ternary operation ,Single crystal ,Powder diffraction ,Solid solution - Abstract
Two intermediate compounds of the system Ca2SiO4–Ca3(PO4)2–CaNaPO4 were synthesized by reaction sintering at 1600°C and analyzed structurally, chemically, and optically. The structure of Ca7(PO4)2(SiO4)2 nagelschmidtite (space group P61, a = 10.7754(1) A, c = 21.4166(3) A) was determined by single crystal X-ray analysis. Its unit cell can be interpreted as a supercell (≈ 2 × a, 3 × c) of the high-temperature polymorph α-Ca2SiO4. Evidence for pseudo-hexagonal symmetry is shown. Using electron microprobe, the solid solution Ca7−xNax(PO4)2+x(SiO4)2−x, (x ≤ 2), of nagelschmidtite was confirmed. Volume thermal expansion coefficients of Ca6.8Na0.2(PO4)2.2(SiO4)1.8 and Ca5.4Na1.5(PO4)3.7(SiO4)0.3 were determined using high-temperature X-ray powder diffraction, yielding mean αV = 3.95 and 5.21 [×10−5/°C], respectively. Ca15(PO4)2(SiO4)6 is a distinct phase in the binary section Ca2SiO4–Ca3(PO4)2 and was found to extend into the ternary space according to Ca15−xNax(PO4)2+x(SiO4)6−x, (x ≤ 0.1). Quenching experiments of the latter allowed for structural analysis of a strongly disordered, defective high-temperature polymorph of the α-Ca2SiO4–α-Ca3(PO4)2 solid solution. Structural relations between nagelschmidtite, Ca15(PO4)2(SiO4)6 and the end-member compounds of the system are discussed.
- Published
- 2015
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24. Fabrication, characterization, and application-matched design of thermoelectric modules based on Half-Heusler FeNbSb and TiNiSn
- Author
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Corsin Battaglia, Yinglu Tang, Hans Rudolf Elsener, Daniel Widner, Benjamin Kunz, Remo N. Widmer, Daniel Landmann, Renato Huber, and Peter Rickhaus
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Thermoelectric generator ,Fabrication ,Materials science ,Internal combustion engine ,Multiphysics ,Heat exchanger ,General Physics and Astronomy ,Mechanical engineering ,Heat transfer coefficient ,Heat sink ,Thermoelectric materials - Abstract
We describe the fabrication of thermoelectric modules based on Half-Heusler TiNiSn and FeNbSb and their performance assessment under different boundary conditions. Module design is guided by a multiphysics model implementing experimentally determined thermoelectric materials properties. We consider two types of boundary conditions: first, imposing fixed cold- and hot-side temperatures onto the module, and second, imposing fixed values for the heat transfer coefficients between module and heat sink and source, representative for a waste-heat-recovery system using the exhaust heat of an internal combustion engine. We compare the modeling results with experimental data obtained from Half-Heusler modules integrated into a heat exchanger mounted to the exhaust of a compact van.
- Published
- 2019
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25. Effects of heat treatment on red gemstone spinel: single-crystal X-ray, Raman, and photoluminescence study
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Thomas Armbruster, Remo N. Widmer, and Anna-Kathrin Malsy
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Quenching ,Photoluminescence ,Chemistry ,Spinel ,Analytical chemistry ,Mineralogy ,engineering.material ,Spectral line ,Bond length ,symbols.namesake ,Geochemistry and Petrology ,550 Earth sciences & geology ,engineering ,symbols ,General Materials Science ,Raman spectroscopy ,Spectroscopy ,Single crystal - Abstract
A red spinel, MgAl2O4, from Burma (Myanmar) containing as chromophores ca. 0.5 wt% of each Cr2O3 and V2O3, was sequentially heated for at least 72 h at temperatures ranging from 600 °C to 1,100 °C. The untreated and quenched samples were examined with single-crystal X-ray diffraction (XRD), Raman spectroscopy and photoluminescence spectroscopy. XRD results display a linear decrease of the cell parameter a and a continuous shift of the oxygen coordinate u, u, u at 3 m toward lower values with increasing temperature and associated Mg, Al disorder: T(Mg1-x Al x )M(Al2-x Mg x )O4. The natural spinel has x = 0.157(2) and reaches x = 0.286(4) after quenching from 1,100 °C. In its natural state, M–O and T–O distances are 1.9226(2) and 1.9361(4) A. With increasing inversion of Mg from the tetrahedrally coordinated T to the octahedrally coordinated M site, M–O distances increase at 1,100 °C to 1.9333(4) A and T–O distances decrease to 1.9130(8) A. The crossover temperature, at which T–O and M–O distances become equal (i.e., 1.927 A), is found to be at 650 °C and corresponds to an inversion parameter x = 0.208(3). With increasing heat treatment, Raman spectra of quenched samples become significantly broadened and a peak characteristic for Mg, Al disorder at 721 cm−1 firstly appears for a crystal quenched from 800 °C with x = 0.248(4). At room temperature, photoluminescence spectra are dominated by a strong R line at 684.5 nm accompanied by poorly resolved N lines: N1 (687 nm), N2 (688 nm), and N3 (689 nm). N lines are caused by different Mg, Al environments of Cr3+. With increasing inversion parameter (x), the R line decreases in intensity and the N lines become prominent leading to strongly broadened peaks with a maximum shifted toward higher wave lengths (687.5 nm at 1,100 °C). Criteria for the detection of heat treatment on gemstone spinel applicable to gemological routine examination are provided. Extrapolation of u, a, and bond lengths from heat-treated Burma spinel toward the natural crystal suggests a retrograde “closing temperature” of ca. 400 ± 100 °C at which Mg, Al disorder was frozen.
- Published
- 2015
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26. Contents Vol. 211, 2005
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Christos C. Zouboulis, M. Monika Weber, Selim Aractingi, Venkata Putcha, Isabelle Daigle, M.A. Duchosal, J.L. Arranz López, Hiroyuki Matsue, E. Gambillara, Jann Lübbe, D.A. Fairhurst, P. Dellamonica, Christian Surber, Dominique Bonneau, Emmanuel Laffitte, Olivier Sorg, Katrin Kerl, Dan Lipsker, Karin Thoss, Wolfram Sterry, Henrik Møller, Maria Morales, E. Counillon, Alice Quinart, P. Del Giudice, Andreas J. Bircher, Mohammad Reza Fallahi, Agustin Llopis, Uwe Trefzer, Alexander C. Katoulis, Jean-Hilaire Saurat, Nicholas G. Stavrianeas, Jørn Olsen, Marc Buffet, Pierre Carraux, Thomas J. Brill, N. Kunzle, Mohammad Nikbakhsh, Hans-Peter Baum, J.-H. Saurat, Ambros Hügin, M. Grelier, Paulette Bioulac-Sage, Naohito Hatta, Farshad Farnaghi, Lutz Kowalzick, Philippe Revel, Carol M. Artlett, Gholamhosein R. Omrani, T. Rodriguez Bravo, Sébastien Lepreux, Katharina Spanaus Schlapbach, Carolina Pellanda, Günter Burg, Günther F.L. Hofbauer, Christine Labreze, N. Widmer, H. Zeller, Jürgen Quietzsch, Hassan Seirafi, A. Carlotti, I. Schuffenecker, Sylvie De Maricourt, Luca Borradori, Rahman Nazari, Sofia Georgala, Roland Blum, Laurence Doelker, Christian Tran, Emmanuel Molinari, Christophe Antille, Jürgen Lademann, Akiko Nagasaka, I. Masouyé, P. Lesavre, Mitra Amini, J.-M. Pönnighaus, Renato G. Panizzon, Amin Parhizgar, L.A. Decosterd, H. Zachariae, Daniel Mischke, S.M. Clark, Julie De Quatrebarbes, E. Laffitte, Ute Jacobi, Evelyne Leemans, Giovanni Luigi Capella, Diamant Thaçi, Nicolas Dupin, Hans-Uwe Simon, Reinhard Dummer, Eva M. Valesky, Julien Gautier, Denise Grand, Behrooz Kasraee, Jörg Willers, Thierry André, F. Vandenbos, T. Kovacsovics, Parisa Mansoori, Aiko Miyahara, Heidrun Ziegler, L. Garcia Martinez, Gürkan Kaya, Shinji Shimada, Julien Autier, J.-P. Venetz, Farhad Handjani, M. Pascual, Roland Kaufmann, Thomas Elshorst-Schmidt, Arash Taheri, Regina Treudler, Martine Neau-Cransac, Pierre Vabres, E. Elena Sorando, Maryam Akhyani, Jean Saric, Helen S. Evans, Isabelle Gorin, and Silvio Hemmi
- Subjects
Dermatology - Published
- 2005
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- View/download PDF
27. η-ρ Pareto optimization of bidirectional half-cycle discontinuous-conduction-mode series-resonant DC/DC converter with fixed voltage transfer ratio
- Author
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Jonas E. Huber, Johann W. Kolar, Florian Krismer, G. Ortiz, and N. Widmer
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Power optimizer ,Forward converter ,Engineering ,Control theory ,business.industry ,Flyback converter ,Boost converter ,Charge pump ,Ćuk converter ,business ,Low voltage ,DC bias - Abstract
In solid-state-transformer technology, the isolation and power transfer between low voltage and medium voltage side is performed by a high power DC/DC converter. This DC/DC converter provides a defined ratio between input and output voltages, whereby, in order to reduce switching losses, zero-current-switching modulation schemes are often mandatory. The series-resonant-converter operated in half-cycle discontinuous-conduction-mode possesses all the aforementioned features, thus making it highly attractive for solid-state-transformer applications. For this reason, a comprehensive analytical model of the converter's static and dynamic behavior is provided in this paper. In addition, a method to model the switching losses under ZCS conditions, which is based on the behavior of the stored charge in the semiconductors, is presented. This enables an efficiency/power density (η-ρ) Pareto optimization of the aforementioned converter system.
- Published
- 2013
- Full Text
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28. Sludge Combustor Using Swirl and Active Combustion Control
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J. Cole, Kenneth J. Wilson, T. Parr, N. Widmer, and K. Schadow
- Subjects
Waste treatment ,Engineering ,Afterburner ,Waste management ,business.industry ,Combustor ,Overall performance ,Active control ,business ,Combustion ,Particulate suspension - Abstract
A research program directed at developing technology for compact shipboard incinerators for sludges is described. The concept utilizes previously developed Vortex Containment Combustor (VCC) as a primary unit with an active combustion control afterburner (AB). The overall power scale of the combined system is 0.15MJoule/sec and has a target sludge processing rate of 0.75 liter/min. Tests were undertaken to evaluate the particulate suspension qualities of the VCC and the overall performance of the combined VCC I active control AB processing intermediate levels of a surrogate sludge.
- Published
- 2000
- Full Text
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29. Fabrication and Testing for Solar Detoxification Project
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K. Beninga, N. Widmer, J. Cole, and S. Doty
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Engineering ,Waste management ,business.industry ,Soil vapor extraction ,Extraction (chemistry) ,Thermal desorption ,Contamination ,Solar energy ,Soil contamination ,Incineration ,medicine ,business ,Activated carbon ,medicine.drug - Abstract
A demonstration of a solar detoxification system was conducted for the U.S. Army Environmental Center (USAEC) at Science Applications International Corporation's (SAIC's) test site near Golden, Colorado, in June 1997. The purpose of this demonstration test was to evaluate the use of solar energy for thermally detoxifying organic compounds representative of soil contamination found at U.S. Army sites. The demonstration test was carried out under the third of three tasks conducted under contract by SAIC. Under Tasks I and II, the conceptual and detailed design of a pilot-scale system was completed. Under Task III, fabrication and testing of the system were accomplished. This document presents the results obtained during the Task III demonstration test. The purpose of this demonstration test was to evaluate the use of solar energy to thermally detoxify organic compounds removed from contaminated media by ex situ (such as thermal desorption) or in situ (such as soil vapor extraction) treatment systems, or desorbed from pretreatment matrices (such as activated carbon). Extraction systems are commercially available so the step of directly extracting organic from contaminated soil was excluded from the pilot-scale demonstration. Rather, the pilot-scale demonstration test focused on evaluating ultraviolet (UV)-rich solar destruction of volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) by a solar incinerator and the environmental control of the resulting off gases.
- Published
- 1997
- Full Text
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30. Subject Index Vol. 211, 2005
- Author
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P. Del Giudice, Ambros Hügin, Marc Buffet, Regina Treudler, T. Rodriguez Bravo, Arash Taheri, Carolina Pellanda, Thomas J. Brill, Martine Neau-Cransac, Andreas J. Bircher, Emmanuel Molinari, Jørn Olsen, E. Gambillara, Olivier Sorg, J.-M. Pönnighaus, Christophe Antille, Paulette Bioulac-Sage, Denise Grand, Thierry André, Alexander C. Katoulis, I. Masouyé, M.A. Duchosal, Julie De Quatrebarbes, H. Zachariae, Henrik Møller, Alice Quinart, S.M. Clark, Amin Parhizgar, Giovanni Luigi Capella, Hans-Uwe Simon, Carol M. Artlett, M. Grelier, Julien Gautier, Selim Aractingi, Gürkan Kaya, Sébastien Lepreux, Julien Autier, Pierre Vabres, Mohammad Reza Fallahi, Jean-Hilaire Saurat, J.-P. Venetz, I. Schuffenecker, M. Monika Weber, Daniel Mischke, Maryam Akhyani, Günther F.L. Hofbauer, Venkata Putcha, Pierre Carraux, Farhad Handjani, Akiko Nagasaka, E. Counillon, Diamant Thaçi, Jann Lübbe, Farshad Farnaghi, Lutz Kowalzick, M. Pascual, Christian Surber, Dominique Bonneau, Dan Lipsker, Emmanuel Laffitte, Katrin Kerl, T. Kovacsovics, Roland Kaufmann, Thomas Elshorst-Schmidt, Agustin Llopis, Hassan Seirafi, Jörg Willers, Luca Borradori, Parisa Mansoori, Shinji Shimada, Heidrun Ziegler, L.A. Decosterd, N. Kunzle, Rahman Nazari, Sofia Georgala, Christine Labreze, F. Vandenbos, Jürgen Lademann, Nicolas Dupin, Behrooz Kasraee, Christos C. Zouboulis, Isabelle Daigle, P. Lesavre, Mitra Amini, Hiroyuki Matsue, Uwe Trefzer, Philippe Revel, Nicholas G. Stavrianeas, J.L. Arranz López, Karin Thoss, Jürgen Quietzsch, Sylvie De Maricourt, D.A. Fairhurst, P. Dellamonica, Renato G. Panizzon, Hans-Peter Baum, Reinhard Dummer, Ute Jacobi, Evelyne Leemans, Helen S. Evans, Maria Morales, Eva M. Valesky, Isabelle Gorin, Katharina Spanaus Schlapbach, N. Widmer, Laurence Doelker, Christian Tran, Wolfram Sterry, Aiko Miyahara, L. Garcia Martinez, Roland Blum, Silvio Hemmi, E. Elena Sorando, Jean Saric, H. Zeller, E. Laffitte, Gholamhosein R. Omrani, Mohammad Nikbakhsh, A. Carlotti, J.-H. Saurat, Naohito Hatta, and Günter Burg
- Subjects
Index (economics) ,Statistics ,Subject (documents) ,Dermatology ,Mathematics - Published
- 2005
- Full Text
- View/download PDF
31. Acknowledgement to Referees for Dermatology 2005
- Author
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M. Grelier, Denise Grand, Thierry André, Paulette Bioulac-Sage, Henrik Møller, Thomas J. Brill, Regina Treudler, Pierre Carraux, Sébastien Lepreux, Carol M. Artlett, Christophe Antille, I. Masouyé, Silvio Hemmi, Amin Parhizgar, Alice Quinart, Gholamhosein R. Omrani, S.M. Clark, D.A. Fairhurst, P. Del Giudice, Ambros Hügin, E. Elena Sorando, A. Carlotti, Nicholas G. Stavrianeas, Martine Neau-Cransac, P. Dellamonica, Jean Saric, Farshad Farnaghi, I. Schuffenecker, Emmanuel Laffitte, Katrin Kerl, Lutz Kowalzick, Marc Buffet, Selim Aractingi, M. Monika Weber, Julien Autier, L.A. Decosterd, Christine Labreze, J.-P. Venetz, Agustin Llopis, Aiko Miyahara, Jürgen Quietzsch, Sylvie De Maricourt, Rahman Nazari, Sofia Georgala, Nicolas Dupin, Venkata Putcha, E. Laffitte, L. Garcia Martinez, Hans-Peter Baum, Maria Morales, Hassan Seirafi, Behrooz Kasraee, Diamant Thaçi, Jann Lübbe, Luca Borradori, Christian Surber, Dominique Bonneau, Laurence Doelker, Christian Tran, E. Counillon, F. Vandenbos, Dan Lipsker, Günter Burg, Gürkan Kaya, Renato G. Panizzon, Helen S. Evans, Ute Jacobi, Evelyne Leemans, Eva M. Valesky, Mohammad Reza Fallahi, Katharina Spanaus Schlapbach, Roland Blum, Isabelle Gorin, N. Widmer, Reinhard Dummer, J.L. Arranz López, M.A. Duchosal, Karin Thoss, Wolfram Sterry, Carolina Pellanda, H. Zeller, Shinji Shimada, Emmanuel Molinari, Akiko Nagasaka, J.-M. Pönnighaus, T. Kovacsovics, Julie De Quatrebarbes, Daniel Mischke, Mohammad Nikbakhsh, Giovanni Luigi Capella, Hans-Uwe Simon, J.-H. Saurat, Julien Gautier, Naohito Hatta, Jörg Willers, Heidrun Ziegler, Günther F.L. Hofbauer, Philippe Revel, N. Kunzle, Pierre Vabres, P. Lesavre, Mitra Amini, Maryam Akhyani, Farhad Handjani, M. Pascual, Jürgen Lademann, Uwe Trefzer, Roland Kaufmann, Thomas Elshorst-Schmidt, Arash Taheri, Andreas J. Bircher, Parisa Mansoori, Jørn Olsen, Hiroyuki Matsue, E. Gambillara, Alexander C. Katoulis, Jean-Hilaire Saurat, H. Zachariae, Isabelle Daigle, T. Rodriguez Bravo, Christos C. Zouboulis, and Olivier Sorg
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Medical education ,Acknowledgement ,Dermatology ,Psychology - Published
- 2005
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- View/download PDF
32. Comparative inhibition of mammalian amylases by goat antisera to hog pancreatic amylase
- Author
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David N. Widmer, Patricia A. Prell, Wanda M. Pavord, and Robert L. McGeachin
- Subjects
Swine ,Guinea Pigs ,Biology ,Salivary Glands ,Mice ,Dogs ,Animals ,Humans ,Amylase ,Pancreas ,General Environmental Science ,Antiserum ,Goats ,Immune Sera ,Molecular biology ,Enzymes ,Rats ,Enzyme inhibition ,Biochemistry ,Liver ,Amylases ,biology.protein ,Cats ,General Earth and Planetary Sciences ,Rabbits ,Antibody - Abstract
1. 1. Antisera to hog pancreatic amylase, having enzyme-inhibiting properties, were produced in goats. 2. 2. More cross-reactions of the goat antisera with various mammalian amylases were noted, compared to previous studies using rabbit antisera, although similarities in enzyme inhibition patterns seemed to follow expected phylogenetic relationships. 3. 3. Enzyme inhibition studies using these antisera showed that the liver amylases of various mammalian species are different from the pancreatic and salivary amylases of these species. 4. 4. Although in previous studies with rabbit antisera to amylase no inhibition of liver amylase had been notes, some inhibition of liver amylase by goat antisera was seen. 5. 5. Differences in the reaction rates of amylase with rabbit antibodies and goat antibodies were noted as were differences in the levels of maximal enzyme inhibition which could be achieved.
- Published
- 1966
33. High-pressure and high-temperature vibrational properties and anharmonicity of carbonate minerals up to 6 GPa and 500 ˚C by Raman spectroscopy
- Author
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Simon A. T. Redfern, Stefan Farsang, and Remo N. Widmer
- Subjects
Calcite ,Smithsonite ,Materials science ,010504 meteorology & atmospheric sciences ,Aragonite ,Analytical chemistry ,Carbonate minerals ,engineering.material ,sub-03 ,010502 geochemistry & geophysics ,01 natural sciences ,Strontianite ,symbols.namesake ,chemistry.chemical_compound ,Geophysics ,chemistry ,Geochemistry and Petrology ,engineering ,symbols ,Raman spectroscopy ,0105 earth and related environmental sciences ,Witherite ,Magnesite - Abstract
Carbonate minerals play a dominant role in the deep carbon cycle. Determining the high-pressure and high-temperature vibrational properties of carbonates is essential to understand their anharmonicity and their thermodynamic properties under crustal and upper mantle conditions. Building on our previous study on aragonite, calcite (both CaCO3 polymorphs), dolomite [CaMg(CO3)2], magnesite (MgCO3), rhodochrosite (MnCO3), and siderite (FeCO3) (Farsang et al. 2018), we have measured the pressure- and temperature-induced frequency shifts of Raman-active vibrational modes up to 6 GPa and 500 °C for all naturally occurring aragonite- and calcite-group carbonate minerals, including cerussite (PbCO3), strontianite (SrCO3), witherite (BaCO3), gaspeite (NiCO3), otavite (CdCO3), smithsonite (ZnCO3), and spherocobaltite (CoCO3). Our Raman and XRD measurements show that cerussite decomposes to a mixture of Pb2O3 and tetragonal PbO between 225 and 250 °C, smithsonite breaks down to hexagonal ZnO between 325 and 400 °C, and gaspeite to NiO between 375 and 400 °C. Spherocobaltite breaks down between 425 and 450 °C and otavite between 375 and 400 °C. Due to their thermal stability, carbonates may serve as potential reservoirs for several metals (e.g., Co, Ni, Zn, Cd) in a range of crustal and upper mantle environments (e.g., subduction zones). We have determined the isobaric and isothermal equivalents of the mode Grüneisen parameter and the anharmonic parameter for each Raman mode and compare trends in vibrational properties as a function of pressure, temperature, and chemical composition with concomitant changes in structural properties. Finally, we use the anharmonic parameter to calculate the thermal contribution to the internal energy and entropy, as well as the isochoric and isobaric heat capacity of certain carbonates.
34. Cryphonectria hypovirus 1 (CHV-1) from Croatia - Sequence Variation and Impact on Fungal Host
- Author
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Krstin, Ljiljana, Ježić, Marin, Rigling, Daniel, Ćurković-Perica, Mirna, and Touraev, A., Stewart, C. N., Widmer, A.
- Subjects
fungi ,Ascomycete fungus ,hypovirulence ,sporulation - Abstract
Chryphonectria hypovirus 1 (CHV-1) is a successful natural biological control agent for the chestnut blight fungus Cryphonectria parasitica. This fungus is an agressive imported pathogen of chestnut. CHV-1 reduces its virulence and sporulation. Thirty-six CHV-1 isolates from Croatia were characterized by sequencing hypoviral open reading frame ORF-A. Effect of different hypovirus isolates on the host was assessed by measuring growth and sporulation of infected C. parasitica strains in vitro. Most of Croatian virus isolates had medium effect on the fungus. One hypoviral isolate sampled on island Cres reduced fungal growth and sporulation significantly better than the others, but it was still weaker than French CHV-1 isolate EP713.
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- 2012
35. Genetic Diversity and Invasion Pathways of Cryphonectria parasitica in Croatia and Slovenia Inferred by SCAR Markers
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Ježić, Marin, Krstin, Ljiljana, Rigling, Daniel, Ćurković-Perica, Mirna, and Touraev, A., Stewart, C. N., Widmer, A.
- Subjects
fungi ,human activities ,diversity ,invasion ,Cryphonectria parasitica - Abstract
The ascomycete fungus Cryphonectria parasitica is an aggressive pathogen of sweet chestnut (Castanea sativa Mill.) introduced into Europe at the beginning of 20th century. Since then, it has spread throughout the chestnut-growing areas, with higher diversity in older populations and lower diversity in expanding ranges. To reconstruct the invasion events and estimate diversity of C. parasitica in Croatia and Slovenia, 180 samples were genotyped using 11 sequence-characterized amplified region (SCAR) markers. Eight were found to be polymorphic, and 66 different haplotypes were identified. Our research suggests two separate introductions of C. parasitica in these regions and implies northern Italy as the first source of infection, with the subsequent introduction from south-eastern Europe, which contributed significantly to the diversity of the C. parasitica in our study area. We speculated that most haplotypes have been derived through sexual recombination between a few divergent haplotypes, which suggests that multiple introductions and sexual reproduction are important for the formation of genetically diverse C. parasitica populations.
- Published
- 2012
36. HEV in Blood Donors in Switzerland: The Route to Safe Blood Products.
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Serricchio M, Gowland P, Widmer N, Stolz M, and Niederhauser C
- Abstract
The hepatitis E virus (HEV) is an emerging infectious disease with zoonotic potential, causing acute hepatitis in humans. Infections in healthy individuals are often acute, self-limiting and asymptomatic, thus leading to the underdiagnosis of HEV infections. Asymptomatic HEV infections pose a problem for blood transfusion safety by increasing the risk for transfusion-transmitted HEV infections. Here, we describe the journey from determining the HEV seroprevalence among blood donors to the implementation of routine HEV RNA testing of all blood products in Switzerland in 2018 and summarise the HEV cases detected since. In total, 290 HEV-positive blood donations were detected by mini-pool nucleic acid testing (NAT) in Switzerland in the period of October 2018-December 2023, equal to an incidence of 20.7 per 100,000 donations. Thanks to the implemented scheme, no transfusion-transmitted infections occurred in this period. Furthermore, blood donation monitoring has proven to be an effective means of detecting HEV outbreaks in the general population. HEV cases in Swiss blood donors are caused by two major genotypes, the Swiss-endemic subtypes 3h3 and 3c. Interestingly, 11 HEV cases (5%) were of genotype 3ra, a variant found in wild and farmed rabbits. Our results indicate that mini-pool NAT is an efficient method to reduce the risk of transfusion-transmitted HEV infections.
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- 2024
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37. [Diagnosis and emergency management of radiological incidents].
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Porzi J, Porzi M, Patonnier M, Macri F, Widmer N, Desmettre T, Platon A, Poletti PA, and Gartner BA
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- Humans, Emergency Medical Services methods, Decontamination methods, Radiation Protection methods, Radioactive Hazard Release, Radiation Injuries diagnosis, Radiation Injuries therapy, Radiation Injuries etiology, Radiation Injuries prevention & control
- Abstract
Incidents involving ionizing radiation pose a risk of immediate and long-term clinical consequences for both victims and responders in the event of secondary contamination. Rapid identification of the problem and a coordinated response are crucial. This article summarizes the key challenges related to the emergency management of a single patient or multiple victims, addressing the importance of recognizing such a case, radioprotection measures, decontamination, and available treatments., Competing Interests: Les auteurs n’ont déclaré aucun conflit d’intérêts en relation avec cet article.
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- 2024
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38. Population Pharmacokinetics in Oncology and Its Clinical Applications.
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Widmer N, Guidi M, and Buclin T
- Abstract
Most traditional cytotoxic drugs are characterized by steep dose-response relationships and narrow therapeutic windows [...].
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- 2024
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39. Prevalence of Acute Hepatitis E Virus Infections in Swiss Blood Donors 2018-2020.
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Niederhauser C, Gowland P, Widmer N, Amar El Dusouqui S, Mattle-Greminger M, Gottschalk J, and Frey BM
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- Humans, Switzerland epidemiology, Male, Female, Adult, Prevalence, Middle Aged, Hepatitis Antibodies blood, Immunoglobulin M blood, Young Adult, Immunoglobulin G blood, Viral Load, Aged, Adolescent, Hepatitis E epidemiology, Hepatitis E transmission, Hepatitis E virology, Blood Donors statistics & numerical data, Hepatitis E virus genetics, Hepatitis E virus immunology, Hepatitis E virus classification, Hepatitis E virus isolation & purification, RNA, Viral genetics, RNA, Viral blood, Genotype
- Abstract
Introduction: Hepatitis E virus (HEV) genotype 3 is the major cause of acute viral hepatitis in several European countries. It is acquired mainly by ingesting contaminated pork, but has also been reported to be transmitted through blood transfusion. Although most HEV infections, including those via blood products, are usually self-limiting, they may become chronic in immunocompromised persons. It is thus essential to identify HEV-infected blood donations to prevent transmission to vulnerable recipients., Aims: Prior to the decision whether to introduce HEV RNA screening for all Swiss blood donations, a 2-year nationwide prevalence study was conducted., Methods: All blood donations were screened in pools of 12-24 samples at five regional blood donation services, and HEV RNA-positive pools were subsequently resolved to the individual donation index donation (X). The viral load, HEV IgG and IgM serology, and HEV genotype were determined. Follow-up investigations were conducted on future control donations (X + 1) and previous archived donations of the donor (X - 1) where available., Results: Between October 2018 and September 2020, 541,349 blood donations were screened and 125 confirmed positive donations were identified (prevalence 1:4331 donations). At the time of blood donation, the HEV RNA-positive individuals were symptom-free. The median viral load was 554 IU/mL (range: 2.01-2,500,000 IU/mL). Men (88; 70%) were more frequently infected than women (37; 30%), as compared with the sex distribution in the Swiss donor population (57% male/43% female, p < 0.01). Of the 106 genotyped cases (85%), all belonged to genotype 3. Two HEV sub-genotypes predominated; 3h3 (formerly 3s) and 3c. The remaining sub-genotypes are all known to circulate in Europe. Five 3ra genotypes were identified, this being a variant associated with rabbits. In total, 85 (68%) X donations were negative for HEV IgM and IgG. The remaining 40 (32%) were positive for HEV IgG and/or IgM, and consistent with an active infection. We found no markers of previous HEV in 87 of the 89 available and analyzed archive samples (X - 1). Two donors were HEV IgG-positive in the X - 1 donation suggesting insufficient immunity to prevent HEV reinfection. Time of collection of the 90 (72%) analyzed X + 1 donations varied between 2.9 and 101.9 weeks (median of 35 weeks) after X donation. As expected, none of those tested were positive for HEV RNA. Most donors (89; 99%) were positive for anti-HEV lgG/lgM (i.e., seroconversion). HEV lgM-positivity (23; 26%) indicates an often-long persistence of lgM antibodies post-HEV infection., Conclusion: The data collected during the first year of the study provided the basis for the decision to establish mandatory HEV RNA universal screening of all Swiss blood donations in minipools, a vital step in providing safer blood for all recipients, especially those who are immunosuppressed.
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- 2024
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40. Managing the COVID-19 health crisis: a survey of Swiss hospital pharmacies.
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Schumacher L, Dhif Y, Bonnabry P, and Widmer N
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- Humans, Pandemics, Switzerland epidemiology, Pharmacists, Pharmaceutical Preparations, Hospitals, Surveys and Questionnaires, COVID-19 epidemiology, Pharmacies, Pharmacy Service, Hospital
- Abstract
Background: The COVID-19 pandemic strained healthcare systems immensely as of 2020. Switzerland's hospital pharmacies' responses during the first wave were surveyed with a view to improving the quality of pharmaceutical management in future health crises., Methods: An online survey was sent to the heads of all of Switzerland's hospital pharmacies. The questionnaire was organised into eleven sections of questions covering many topics regarding the management of COVID-19's first wave. Data collection occurred from May to June 2020., Results: Analyses were performed using the 43 questionnaires (66%), with at least one answer per questionnaire, out of 65 distributed. Seventeen of 41 pharmacies responding (41%) had existing standard operating procedures or pandemic plans and 95% of these (39/41) set up crisis management steering committees. Twenty-nine of 43 pharmacies responding (67%) created new activities to respond to the pandemic's specific needs. Twenty-six of 39 pharmacies responding (67%) created new drug lists for: COVID-19-specific treatments (85%; 22/26), sedatives (81%; 21/26), anaesthetics (77%; 20/26) and antibiotics (73%; 19/26). Drug availability in designated COVID-19 wards was managed by increasing existing stocks (54%; 22/41 pharmacies) and creating extra storage space (51%; 21/41). Two drugs generated the greatest concern about shortages: propofol (49%; 19/39 pharmacies) and midazolam (44%; 17/39). Remdesivir stocks ran out in 26% of pharmacies (10/39). Twelve of 43 pharmacies (28%) drafted specific new documents to respond to medical needs regarding drug administration, 12 (28%) did so for drug preparation and 10 (23%) did so for treatment choices., Conclusions: Switzerland's hospital pharmacies encountered many challenges related to the COVID-19 crisis and had to find solutions quickly, effectively and safely. The survey highlighted the key role that hospital pharmacies played in many aspects of the pandemic by providing logistical and clinical support to medical and nursing care teams. The lessons and experiences outlined could be used to improve the quality of hospital pharmacies' readiness for similar future events., (© 2023. BioMed Central Ltd., part of Springer Nature.)
- Published
- 2023
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- View/download PDF
41. Properties of three collagen scaffolds in comparison with native connective tissue: an in-vitro study.
- Author
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Solderer A, Widmer N, Gubler A, Fischer KR, Hicklin SP, and Schmidlin PR
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- Swine, Animals, Collagen pharmacology, Collagen chemistry, Connective Tissue, Collagenases, Tissue Scaffolds chemistry, Acellular Dermis
- Abstract
Purpose: To evaluate collagen scaffolds (CS) in terms of their in vitro resorption behavior, surface structure, swelling behavior, and mechanical properties in physiologically simulated environments, compared with porcine native connective tissue., Materials and Methods: Three test materials-one porcine collagen matrix (p-CM), two acellular dermal matrices (porcine = p-ADM, allogenic = a-ADM)-and porcine native connective tissue (p-CTG) as a control material were examined for resorption in four solutions using a high-precision scale. The solutions were artificial saliva (AS) and simulated body fluid (SBF), both with and without collagenase (0.5 U/ml at 37 °C). In addition, the surface structures of CS were analyzed using a scanning electron microscope (SEM) before and after exposure to AS or SBF. The swelling behavior of CS was evaluated by measuring volume change and liquid absorption capacity in phosphate-buffered saline (PBS). Finally, the mechanical properties of CS and p-CTG were investigated using cyclic compression testing in PBS., Results: Solutions containing collagenase demonstrated high resorption rates with significant differences (p < 0.04) between the tested materials after 4 h, 8 h and 24 h, ranging from 54.1 to 100% after 24 h. SEM images revealed cross-linked collagen structures in all untreated specimens. Unlike a-ADM, the scaffolds of p-CM and p-ADM displayed a flake-like structure. The swelling ratio and fluid absorption capacity per area ranged from 13.4 to 25.5% among the test materials and showed following pattern: p-CM > a-ADM > p-ADM. P-CM exhibited higher elastic properties than p-ADM, whereas a-ADM, like p-CTG, were barely compressible and lost structural integrity under increasing pressure., Conclusions and Clinical Implications: Collagen scaffolds vary significantly in their physical properties, such as resorption and swelling behavior and elastic properties, depending on their microstructure and composition. When clinically applied, these differences should be taken into consideration to achieve the desired outcomes., (© 2023. Deutsche Gesellschaft für Implantologie im Zahn‐, Mund‐ und Kieferbereich e.V., Japanese Society of Oral Implantology.)
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- 2023
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42. Epidemiology of HEV Infection in Blood Donors in Southern Switzerland.
- Author
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Fontana S, Ripellino P, Niederhauser C, Widmer N, Gowland P, Petrini O, Aprile M, Merlani G, and Bihl F
- Abstract
From 2014 to 2016, the number of hepatitis E virus (HEV) infections in southern Switzerland increased dramatically and suggested food as a potential infection reservoir. We evaluated the effects of food control measures introduced to limit HEV infections, assessing anti-HEV IgG and IgM rates in blood donors before and after the implementation of food control measures in 2017. From 2012 to 2013, we screened 1283, and from 2017 to 2019, we screened 1447 donors for IgG and IgM antibodies. No statistically significant differences were detected for IgG (32.8% from 2012 to 2013 vs. 31.1% from 2017 to 2019, p = 0.337) or IgM rates (2.0% from 2012 to 2013 vs. 2.8% from 2017 to 2019, p = 0.21). Rural provenience and age > 66 are predictors for positive IgG serology. A total of 5.9% of 303 donors included in both groups lost IgG positivity. We also determined nucleic acid testing (NAT) rates after the introduction of this test in 2018, comparing 49,345 donation results from southern Switzerland with those of 625,559 Swiss donor controls, and only 9 NAT-positive donors were found from 2018 to 2023. The high HEV seroprevalence in southern Switzerland may depend on different food supply chains in rural and urban areas. Local preventive measures probably have a limited impact on blood HEV risk; thus, continuous NAT testing is recommended., Competing Interests: The authors declare no conflicts of interest.
- Published
- 2023
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43. Long-Term Effectiveness and Sustainability of Integrating Peer-Assisted Ultrasound Courses into Medical School-A Prospective Study.
- Author
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Weimer JM, Widmer N, Strelow KU, Hopf P, Buggenhagen H, Dirks K, Künzel J, Börner N, Weimer AM, Lorenz LA, Rink M, Bellhäuser H, Schiestl LJ, Kloeckner R, Müller L, and Weinmann-Menke J
- Subjects
- Humans, Prospective Studies, Ultrasonography, Schools, Medical, Kidney
- Abstract
Introduction: Ultrasound diagnostics is an important examination method in everyday clinical practice, but student education is often inadequate for acquiring sufficient basic skills. Individual universities have therefore started integrating (extra)curricular training concepts into medical education. This study aimed to evaluate sustainable skills development through participation in peer-assisted ultrasound courses., Methods: From 2017, students in the clinical part of medical school could opt for extracurricular peer-assisted ultrasound courses. Depending on the format (10-week course/2-day compact course) these comprised 20 teaching units focusing on abdominal and emergency ultrasonography. Students attending compulsory workshops at the start of their practical year were enrolled in this study, allowing for a comparison between the study group (attended ultrasound course) and the control group (did not attend ultrasound course). Competency from two out of four practical exams (subjects: "aorta", "gallbladder", "kidney" and "lung") was measured, and a theory test on the same subject areas ("pathology recognition") was administered. Additional questions concerned biographical data, subjective competency assessment (7-point Likert scale), and "attitude to ultrasound training in the curriculum"., Results: Analysis included 302 participants in total. Ultrasound courses had been attended on average 2.5 years earlier (10-week course) and 12 months earlier (2-day compact course), respectively. The study group ( n = 141) achieved significantly better results than the control group ( n = 161) in the long-term follow-up. This applies both to practical exams ( p < 0.01) and theory tests ( p < 0.01). After course attendance, participants reported a significantly higher subjective assessment of theoretical ( p < 0.01) and practical ( p < 0.01) ultrasound skills., Conclusions: Peer-assisted ultrasound courses can sustainably increase both theoretical and practical competency of medical students. This highlights the potential and need for standardised implementation of ultrasound courses in the medical education curriculum.
- Published
- 2023
- Full Text
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44. Do quantitative levels of antispike-IgG antibodies aid in predicting protection from SARS-CoV-2 infection? Results from a longitudinal study in a police cohort.
- Author
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Sendi P, Widmer N, Branca M, Thierstein M, Büchi AE, Güntensperger D, Blum MR, Baldan R, Tinguely C, Heg D, Theel ES, Berbari E, Tande AJ, Endimiani A, Gowland P, and Niederhauser C
- Subjects
- Humans, Longitudinal Studies, Cohort Studies, Cross-Sectional Studies, Police, SARS-CoV-2, Immunoglobulin G, COVID-19
- Abstract
In a COVID-19 sero-surveillance cohort study with predominantly healthy and vaccinated individuals, the objectives were (i) to investigate longitudinally the factors associated with the quantitative dynamics of antispike (anti-S1) IgG antibody levels, (ii) to evaluate whether the levels were associated with protection from SARS-CoV-2 infection, and (iii) to assess whether the association was different in the pre-Omicron compared with the Omicron period. The QuantiVac Euroimmun ELISA test was used to quantify anti-S1 IgG levels. The entire study period (16 months), the 11-month pre-Omicron period and the cross-sectional analysis before the Omicron surge included 3219, 2310, and 895 reactive serum samples from 949, 919, and 895 individuals, respectively. Mixed-effect linear, mixed-effect time-to-event, and logistic regression models were used to achieve the objectives. Age and time since infection or vaccination were the only factors associated with a decline of anti-S1 IgG levels. Higher antibody levels were significantly associated with protection from SARS-CoV-2 infection (0.89, 95% confidence interval [CI] 0.82-0.97), and the association was higher during the time period when Omicron was predominantly circulating compared with the ones when Alpha and Delta variants were predominant (adjusted hazard ratio for interaction 0.66, 95% CI 0.53-0.84). In a prediction model, it was estimated that >8000 BAU/mL anti-S1 IgG was required to reduce the risk of infection with Omicron variants by approximately 20%-30% for 90 days. Though, such high levels were only found in 1.9% of the samples before the Omicron surge, and they were not durable for 3 months. Anti-S1 IgG antibody levels are statistically associated with protection from SARS-CoV-2 infection. However, the prediction impact of the antibody level findings on infection protection is limited., (© 2023 The Authors. Journal of Medical Virology published by Wiley Periodicals LLC.)
- Published
- 2023
- Full Text
- View/download PDF
45. Precision Oncology by Point-of-Care Therapeutic Drug Monitoring and Dosage Adjustment of Conventional Cytotoxic Chemotherapies: A Perspective.
- Author
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Briki M, André P, Thoma Y, Widmer N, Wagner AD, Decosterd LA, Buclin T, Guidi M, and Carrara S
- Abstract
Therapeutic drug monitoring (TDM) of conventional cytotoxic chemotherapies is strongly supported yet poorly implemented in daily practice in hospitals. Analytical methods for the quantification of cytotoxic drugs are instead widely presented in the scientific literature, while the use of these therapeutics is expected to keep going for longer. There are two main issues hindering the implementation of TDM: turnaround time, which is incompatible with the dosage profiles of these drugs, and exposure surrogate marker, namely total area under the curve (AUC). Therefore, this perspective article aims to define the adjustment needed from current to efficient TDM practice for cytotoxics, namely point-of-care (POC) TDM. For real-time dose adjustment, which is required for chemotherapies, such POC TDM is only achievable with analytical methods that match the sensitivity and selectivity of current methods, such as chromatography, as well as model-informed precision dosing platforms to assist the oncologist with dose fine-tuning based on quantification results and targeted intervals.
- Published
- 2023
- Full Text
- View/download PDF
46. From Personalized to Precision Medicine in Oncology: A Model-Based Dosing Approach to Optimize Achievement of Imatinib Target Exposure.
- Author
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Goutelle S, Guidi M, Gotta V, Csajka C, Buclin T, and Widmer N
- Abstract
Imatinib is a targeted cancer therapy that has significantly improved the care of patients with chronic myeloid leukemia (CML) and gastrointestinal stromal tumor (GIST). However, it has been shown that the recommended dosages of imatinib are associated with trough plasma concentration (Cmin) lower than the target value in many patients. The aims of this study were to design a novel model-based dosing approach for imatinib and to compare the performance of this method with that of other dosing methods. Three target interval dosing (TID) methods were developed based on a previously published PK model to optimize the achievement of a target Cmin interval or minimize underexposure. We compared the performance of those methods to that of traditional model-based target concentration dosing (TCD) as well as fixed-dose regimen using simulated patients ( n = 800) as well as real patients' data ( n = 85). Both TID and TCD model-based approaches were effective with about 65% of Cmin achieving the target imatinib Cmin interval of 1000-2000 ng/mL in 800 simulated patients and more than 75% using real data. The TID approach could also minimize underexposure. The standard 400 mg/24 h dosage of imatinib was associated with only 29% and 16.5% of target attainment in simulated and real conditions, respectively. Some other fixed-dose regimens performed better but could not minimize over- or underexposure. Model-based, goal-oriented methods can improve initial dosing of imatinib. Combined with subsequent TDM, these approaches are a rational basis for precision dosing of imatinib and other drugs with exposure-response relationships in oncology.
- Published
- 2023
- Full Text
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47. Management of the COVID-19 Health Crisis: A Survey of Swiss Health Authorities' Responses.
- Author
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Schumacher L, Tinguely Casserini J, Bonnabry P, and Widmer N
- Subjects
- Humans, Switzerland epidemiology, SARS-CoV-2, COVID-19 epidemiology
- Published
- 2023
- Full Text
- View/download PDF
48. The disease burden of Delta and Omicron variants of severe acute respiratory syndrome coronavirus 2 in a predominantly vaccinated and healthy cohort.
- Author
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Sendi P, Branca M, Büchi AE, Widmer N, Tande AJ, and Gowland P
- Subjects
- Humans, Cost of Illness, Cohort Studies, SARS-CoV-2, COVID-19 epidemiology, COVID-19 prevention & control
- Published
- 2022
- Full Text
- View/download PDF
49. Corrigendum to "Validation and clinical application of a multiplex high performance liquid chromatography - Tandem mass spectrometry assay for the monitoring of plasma concentrations of 12 antibiotics in patients with severe bacterial infections" [J. Chromatogr. B 1157 (2020) 122160].
- Author
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Decosterd LA, Mercier T, Ternon B, Cruchon S, Guignard N, Lahrichi S, Pesse B, Rochat B, Burger R, Lamoth F, Pagani JL, Eggimann P, Csajka C, Choong E, Buclin T, Widmer N, André P, and Marchetti O
- Published
- 2022
- Full Text
- View/download PDF
50. Full-scale simulations to improve disaster preparedness in hospital pharmacies.
- Author
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Schumacher L, Senhaji S, Gartner BA, Carrez L, Dupuis A, Bonnabry P, and Widmer N
- Subjects
- Hospitals, Humans, Disaster Planning, Disasters, Pharmacies
- Abstract
Purpose: Assess whether full-scale simulation exercises improved hospital pharmacies' disaster preparedness., Methods: Swiss hospital pharmacies performed successive full-scale simulation exercises at least four months apart. An interprofessional team created two scenarios, each representing credible regional-scale disasters involving approximately fifty casualties (a major road accident and a terrorist attack). Four exercise assessors used appraisal forms to evaluate participants' actions and responses during the simulation (rating them using five-point Likert scales)., Results: Four hospital pharmacies performed two full-scale simulation exercises each. Differences between exercises one and two were observed. On average, the four hospitals accomplished 69% ± 6% of the actions expected of them during exercise one. The mean rate of expected actions accomplished increased to 84% ± 7% (p < 0.005) during exercise two. Moreover, the average quality of actions improved from 3.0/5 to 3.6/5 (p = 0.01), and the time required to gather a crisis management team drastically decreased between simulations (from 23 to 5 min). The main challenges were communication (reformulation) and crisis management. Simulation exercise number one resulted in three hospital pharmacies creating disaster action plans and the fourth improving its already existing plan., Conclusion: This study highlighted the value of carrying out full-scale disaster simulations for hospital pharmacies as they improved overall institutional preparedness and increased staff awareness. The number of expected actions accomplished increased significantly. In the future, large-scale studies and concept dissemination are warranted., (© 2022. The Author(s).)
- Published
- 2022
- Full Text
- View/download PDF
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