The positronium chemistry of a Fe solution is studied under full electrochemical control. For this novel approach to positronium electrochemistry, a suitable cell setup is used, which allows simultaneously both electrochemical measurements and positron annihilation spectroscopy. For the Fe redox couple, positronium serves as an ideally suited atomic probe owing to the rather different positronium chemistry of Fe (spin conversion) and Fe (total positronium inhibition and oxidation). This enabled the precise in situ monitoring of oxidation and reduction by means of positron lifetime upon slow cycling voltammetry or galvanostatic charging. The variation of the mean positron lifetime with the Fe concentration ratio could be quantitatively described by a reaction rate model for positronium formation and annihilation. An asymmetric behavior of the variation of the mean positron lifetime with applied potential, as compared to the simultaneously recorded symmetric current-potential curve, could be explained by the stronger influence of Fe on the characteristics of positronium formation and annihilation. The highly reversible galvanostatic charging behavior monitored by positron lifetime underlines the attractive application potentials of positronium electrochemistry for in situ studies of iron-based redox-flow battery electrolytes.
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http://dx.doi.org/10.1063/5.0129255 | DOI Listing |
Materials (Basel)
December 2024
Faculty of Physics and Astronomy, University of Wroclaw, 9 Maxa Born Square, 50-204 Wroclaw, Poland.
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View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
National University of Singapore, Department of Chemical and Biomolecular Engineering, 4 Engineering Drive 4, Blk E5, #02-16, 117585, Singapore, SINGAPORE.
Metal-organic cages (MOCs) have been considered as emerging zero-dimensional (0D) porous fillers to generate molecularly homogenous MOC-based membrane materials. However, the discontinuous pore connectivity and low filler concentrations limit the improvement of membrane separation performance. Herein, we propose the dimension augmentation of MOCs in membranes using three-dimensional (3D) supramolecular MOC networks as filler materials in mixed matrix membranes (MMMs).
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December 2024
Freiburg Materials Research Center, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg im Breisgau, Germany.
Nuclear power plant decommissioning requires the rapid and accurate classification of radioactive waste in narrow spaces and under time constraints. Photon-counting detector technology offers an effective solution for the quick classification and detection of radioactive hotspots in a decommissioning environment. This paper characterizes a 5 mm CdTe Timepix3 detector and evaluates its feasibility as a single-layer Compton camera.
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December 2024
Positron Group "Prof. Alfredo Dupasquier", Faculty of Exact Sciences, Tandil Institute of Materials Physics (IFIMAT), National University of the Center of the Buenos Aires Province (UNCPBA), Pinto 399, 7000 Tandil, Argentina.
The sensitivity of positron annihilation characteristics to changes in the molecular packing in network-forming polymers has been demonstrated since the early 1980s. Positron annihilation lifetime spectroscopy (PALS) is a unique technique that can provide direct information on the free volume in polymers through the experimental parameters of the free volume hole distribution, their mean value, and volume fraction. This knowledge is currently applied for PALS investigations on the main processes that govern the molecular organization in some green polymers when subjected to different synthesis procedures or environmental conditions (humidity, physical aging, temperature).
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December 2024
Civil Engineering Department, Lanzhou Jiaotong University, Lanzhou 730070, China.
This study investigates the effect of microstructural changes in polyurethane coatings on their water resistance properties. Polyurethane coatings with varying diluent contents were prepared and tested for water penetration resistance and mechanical property retention. The time-dependent behavior of water within the coatings at different immersion durations was analyzed using low-field nuclear magnetic resonance (NMR).
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