The general gaseous ionization detectors are not suitable for high energy X-ray industrial computed tomography (HEICT) because of their inherent limitations, especially low detective efficiency and large volume. The goal of this study was to investigate a new type of gaseous detector to solve these problems. The novel detector was made by a metal foil as X-ray convertor to improve the conversion efficiency, and the Gas Electron Multiplier (hereinafter "GEM") was used as electron amplifier to lessen its volume. The detective mechanism and signal formation of the detector was discussed in detail. The conversion efficiency was calculated by using EGSnrc Monte Carlo code, and the transport course of photon and secondary electron avalanche in the detector was simulated with the Maxwell and Garfield codes. The result indicated that this detector has higher conversion efficiency as well as less volume. Theoretically this kind of detector could be a perfect candidate for replacing the conventional detector in HEICT.
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http://dx.doi.org/10.3233/XST-140426 | DOI Listing |
Environ Sci Technol
January 2025
State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
Selective catalytic reduction of NO by NH(NH-SCR) remains challenging for diesel vehicles due to the complex exhaust condition. Cu-SAPO-18 zeolite has emerged as an efficient catalyst for the NH-SCR process, attributed to its unique small pore configuration and high NH-SCR activity. Herein, Zr-modified Cu-SAPO-18 has been fabricated and evaluated for the reduction of NO.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
College of Physics Science and Technology, Yangzhou University, Yangzhou 225009, China.
Developing high-performance solar cells is a practical way to improve clean energy conversion efficiency. However, the performance of solar cells faces challenges such as fast carrier combination, poor stability, and limited solar light harvesting. Herein, we propose a strategy by decorating periodic holes in two-dimensional (2D) porous carbon-nitrogen (CN) materials with a zero-dimensional (0D) semiconducting (ZnO) cluster.
View Article and Find Full Text PDFRev Sci Instrum
January 2025
Institute for Physical Chemistry, University of Göttingen, 37077 Göttingen, Germany.
Surface science instruments require excellent vacuum to ensure surface cleanliness; they also require control of sample temperature, both to clean the surface of contaminants and to control reaction rates at the surface, for example, for molecular beam epitaxy and studies of heterogeneous catalysis. Standard approaches to sample heating within high vacuum chambers involve passing current through filaments of refractory metals, which then heat the sample by convective, radiative, or electron bombardment induced heat transfer. Such hot filament methods lead to outgassing of molecules from neighboring materials that are inadvertently heated; they also produce electrons and ions that may interfere with other aspects of the surface science experiment.
View Article and Find Full Text PDFChem Sci
January 2025
Laboratory of Polymeric Materials, Department of Materials, ETH Zurich Vladimir Prelog Weg 5 8093 Zurich Switzerland
The labile end-groups inherent to many controlled radical polymerization methodologies, including atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain-transfer (RAFT) polymerization, can trigger the efficient chemical recycling of polymethacrylates yielding high percentages of pristine monomer. Yet, current thermal solution ATRP and RAFT depolymerization strategies require relatively high temperatures ( 120-170 °C) to proceed, with slower depolymerization rates, and moderate yields often reported under milder reaction conditions ( lower temperatures). In this work, we seek to promote the low temperature RAFT depolymerization of polymethacrylates regulating the Z-group substitution of dithiobenzoate.
View Article and Find Full Text PDFAcc Mater Res
January 2025
Department of Chemistry, University of Manchester, Manchester M13 9PL, U.K.
Methane (CH), which is the main component of natural gas, is an abundant and widely available carbon resource. However, CH has a low energy density of only 36 kJ L under ambient conditions, which is significantly lower than that of gasoline (. 34 MJ L).
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