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Only approved publications
Magnetochiral effects in geometrically curved magnetic architectures
Symmetry effects are fundamental in condensed matter physics as they define not only interactions but also resulting responses for the intrinsic order parameter depending on its transformation properties with respect to the operations of space and time reversal. Magnetic materials or layer stacks with structural space inversion symmetry breaking obtained much research attention due to the appearance of chiral Dzyaloshinskii-Moriya interaction (DMI) [1,2]. The latter manifests itself in the formation of non-trivial chiral and topological spin textures (e.g. skyrmions, bubbles, homochiral spirals and domain walls), that are envisioned to be utilized for prospective spintronic devices. At present, tailoring magnetochirality is done by the selection of materials and adjustment of their composition. Alternatively, space inversion symmetry breaking of the magnetic order parameter appears in geometrically curved systems [3]. In curvilinear ferromagnets, curvature governs the appearance of geometry-induced chiral and anisotropic responses, which introduce a new toolbox to create artificial chiral nanostructures from achiral magnetic materials suitable for the stabilization of non-trivial chiral textures [4,5].
Recently, much attention was dedicated to the exchange interaction, which enables curvature-induced extrinsic DMI as was proposed theoretically and validated experimentally for the case of conventional achiral magnetic materials [6]. Here, we demonstrate the existence of non-local chiral effects in geometrically curved asymmetric permalloy cap with the vortex texture. Using the full-scale simulation of the asymmetric nanodots we study how the vortex texture is changing with respect to the introduced sample asymmetry.
Reference list
1. I. Dzyaloshinsky, J. Phys. Chem. Solids 4 (1958), 241.
2. T. Moriya, Phys. Rev. Lett. 4 (1960), 228.
3. R. Hertel, SPIN 3 (2013), 1340009.
4. D. Makarov, et al., Adv. Mater. 34 (2021), 2101758.
5. D. D. Sheka, et al., Commun. Phys. 3 (2020), 128.
6. O. M. Volkov, et al., Phys. Rev. Lett. 123 (2019), 077201.
Keywords: Dzyaloshinskii-Moriya interaction; Non-local chirality breaking; Magnetic vortex; Micromagnetics
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Invited lecture (Conferences)
(Online presentation)
NATO Advanced Research Workshop 2023, 25.-28.09.2023, Kyiv, Ukraine
Permalink: https://www.hzdr.de/publications/Publ-38025
Publ.-Id: 38025
Local and non-local effects in curvilinear micromagnetism
Dzyaloshinskii-Moriya interaction, also known as an antisymmetric exchange interaction, is the main source of chiral symmetry breaking effects in micromagnetic systems [1]. The later manifests itself in magnetic materials and layer stacks with structural space inversion symmetry breaking, where it leads to the formation of non-trivial chiral and topological spin textures (e.g. skyrmions, bubbles, homochiral spirals and domain walls). Such textures potentially could be utilized for prospective spintronic devices as a bit carrier. Still, tailoring of magnetochirality is only done by the selection of materials and adjustment of their composition in layer stacks.
Alternatively, we demonstrate that space inversion symmetry breaking of the magnetic order parameter appears in geometrically curved systems [2]. In curvilinear ferromagnets, curvature governs the appearance of geometry-induced chiral and anisotropic responses, which introduce a new toolbox to create artificial chiral nanostructures from achiral magnetic materials suitable for the stabilization of non-trivial chiral textures [2,3]. Moreover, curvilinear geometry also leads to the appearance of non-local chiral effects, that arise from the asymmetry of the top and bottom surfaces and existence of both in- and out-of-plane magnetization components of different parity with respect to the reflection procedure [4]. Recently, we demonstrate the existence of non-local chiral effects in geometrically curved asymmetric permalloy cap with the vortex texture [5]. We find that the equilibrium vortex core obtain both bend and curling deformation, that are dependent on the geometric symmetries and magnetic parameters.
References
[1] A. Fert, N. Reyren and V. Cros, Nature Reviews Materials 2, 17031 (2017).
[2] D. Makarov, O. M. Volkov, A. Kákay, O. V. Pylypovskyi, B. Budinská and O. V. Dobrovolskiy, Adv. Mater. 34, 2101758 (2021).
[3] O. M. Volkov, A. Kákay, F. Kronast, I. Mönch, M.-A. Mawass, J. Fassbender and D. Makarov, Phys. Rev. Lett. 123, 077201 (2019).
[4] D. D. Sheka, O. V. Pylypovskyi, P. Landeros, Y. Gaididei, A. Kákay and D. Makarov, Commun. Phys. 3, 128 (2020).
[5] O. M. Volkov, D. Wolf, O. V. Pylypovskyi, A. Kákay, D. D. Sheka, B. Büchner, J. Fassbender, A. Lubk and D. Makarov, Nat. Commun. 14, 1491 (2023).
Keywords: Dzyaloshinskii-Moriya interaction; Non-local chirality breaking; Curvilinear Magnetism; Micromagnetics; Magnetic vortex
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Invited lecture (Conferences)
”Nanomaterials: Applications & Properties” (IEEE NAP) 2023, 11.-15.09.2023, Bratislava, Slovakia
Permalink: https://www.hzdr.de/publications/Publ-38024
Publ.-Id: 38024
Local and non-local chiral effects in curvilinear nanomagnets
Volkov, O.; Wolf, D.; Pylypovskyi, O.; Kakay, A.; Sheka, D.; Büchner, B.; Faßbender, J.; Lubk, A.; Makarov, D.
Dzyaloshinskii-Moriya interaction, also known as an antisymmetric exchange interaction, is the main source of chiral symmetry breaking effects in micromagnetic systems [1]. The later manifests itself in magnetic materials and layer stacks with structural space inversion symmetry breaking, where it leads to the formation of non-trivial chiral and topological spin textures (e.g. skyrmions, bubbles, homochiral spirals and domain walls). Such textures potentially could be utilized for prospective spintronic devices as a bit carrier. Still, tailoring of magnetochirality is only done by the selection of materials and adjustment of their composition in layer stacks.
Alternatively, we demonstrate that space inversion symmetry breaking of the magnetic order parameter appears in geometrically curved systems [2]. In curvilinear ferromagnets, curvature governs the appearance of geometry-induced chiral and anisotropic responses, which introduce a new toolbox to create artificial chiral nanostructures from achiral magnetic materials suitable for the stabilization of non-trivial chiral textures [2,3]. Moreover, curvilinear geometry also leads to the appearance of non-local chiral effects, that arise from the asymmetry of the top and bottom surfaces and existence of both in- and out-of-plane magnetization components of different parity with respect to the reflection procedure [4]. Recently, we demonstrate the existence of non-local chiral effects in geometrically curved asymmetric permalloy cap with the vortex texture [5]. We find that the equilibrium vortex core obtain both bend and curling deformation, that are dependent on the geometric symmetries and magnetic parameters.
References
[1] A. Fert, N. Reyren and V. Cros, Nature Reviews Materials 2, 17031 (2017).
[2] D. Makarov, O. M. Volkov, A. Kákay, O. V. Pylypovskyi, B. Budinská and O. V. Dobrovolskiy, Adv. Mater. 34, 2101758 (2021).
[3] O. M. Volkov, A. Kákay, F. Kronast, I. Mönch, M.-A. Mawass, J. Fassbender and D. Makarov, Phys. Rev. Lett. 123, 077201 (2019).
[4] D. D. Sheka, O. V. Pylypovskyi, P. Landeros, Y. Gaididei, A. Kákay and D. Makarov, Commun. Phys. 3, 128 (2020).
[5] O. M. Volkov, D. Wolf, O. V. Pylypovskyi, A. Kákay, D. D. Sheka, B. Büchner, J. Fassbender, A. Lubk and D. Makarov, Nat. Commun. 14, 1491 (2023).
Keywords: Dzyaloshinskii-Moriya interaction; Topological spin textures; Magnetic vortex; Curvilinear magnetism
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Lecture (Conference)
Joint Conference of the Italian and European Community of Condensed Matter Physics 2023, 04.-08.09.2023, Milan, Italy
Permalink: https://www.hzdr.de/publications/Publ-38023
Publ.-Id: 38023
Local and non-local chirality breaking effects in curvilinear nanoarchitectures
The main origin of the chiral symmetry breaking and, thus, for the magnetochiral effects in magnetic materials is associated with an antisymmetric exchange interaction, the intrinsic Dzyaloshinskii-Moriya interaction (DMI) [1,2]. The later manifests itself in magnetic materials or layer stacks with structural space inversion symmetry breaking. The DMI is responsible for the formation of non-trivial chiral and topological spin textures (e.g. skyrmions, bubbles, homochiral spirals and domain walls), that are envisioned to be utilized for prospective spintronic devices. At present, tailoring of magnetochirality is done by the selection of materials and adjustment of their composition.
Alternatively, we demonstrate that space inversion symmetry breaking of the magnetic order parameter appears in geometrically curved systems [3]. In curvilinear ferromagnets, curvature governs the appearance of geometry-induced chiral and anisotropic responses, which introduce a new toolbox to create artificial chiral nanostructures from achiral magnetic materials suitable for the stabilization of non-trivial chiral textures [4,5,6]. Moreover, curvilinear geometry also leads to the appearance of non-local chiral effects, that arise from the asymmetry of the top and bottom surfaces and existence of both in- and out-of-plane magnetization components of different parity with respect to the reflection procedure [5]. Recently, we demonstrate the existence of non-local chiral effects in geometrically curved asymmetric permalloy cap with the vortex texture. We find that the equilibrium vortex core obtain both bend and curling deformation, that are dependent on the geometric symmetries and magnetic parameters.
References
[1] I. Dzyaloshinsky, J. Phys. Chem. Solids 4 (1958), 241.
[2] T. Moriya, Phys. Rev. Lett. 4 (1960), 228.
[3] R. Hertel, SPIN 3 (2013), 1340009.
[4] D. Makarov, et al., Adv. Mater. 34 (2021), 2101758.
[5] D. D. Sheka, et al., Commun. Phys. 3 (2020), 128.
[6] O. M. Volkov, et al., Phys. Rev. Lett. 123 (2019), 077201.
Keywords: Dzyaloshinskii-Moriya interaction; Cuvilinear magnetism; 3D magnetic architectures; Micromagnetics; Magnetic vortex
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Invited lecture (Conferences)
The Joint European Magnetic Symposia 2023, 28.08.-01.09.2023, Madrid, Spain
Permalink: https://www.hzdr.de/publications/Publ-38022
Publ.-Id: 38022
Micromagnetic parameters and longitudinal relaxation in ultrathin asymmetrically sandwiched magnetic films
Volkov, O.; Yastremsky, I. A.; Pylypovskyi, O.; Kronast, F.; Abert, C.; Oliveros Mata, E. S.; Makushko, P.; Mawass, M.-A.; Kravchuk, V. P.; Sheka, D.; Ivanov, B. A.; Faßbender, J.; Makarov, D.
Ultrathin asymmetric magnetic films are a prominent material science platform, which combines unique magnetic and electronic properties enabling prospective memory and logic spin-orbitronic devices. Here, we present the quantification mechanism to distinguish all static and dynamic micromagnetic parameters of the layer stack based on magnetometry [1] and quasi-static morphology experiments on domain wall equilibrium tilts [2]. The DW damping is found to be about 0.1 [2] and it is demonstrated to arise from a longitudinal relaxation being dominant among transversal mechanisms for ultrathin films [3].
[1] I. A. Yastremsky et al., Phys. Rev. Appl. 12, 064038 (2019).
[2] O. M. Volkov et al., Phys. Rev. Appl. 15, 034038 (2021).
[3] I. A. Yastremsky et al., Phys. Rev. Appl. 17, L061002 (2022).
Keywords: Ultrathin asymmetric magnetic film; Domain wall; Spin-otbit torque; Micromagnetics
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Lecture (Conference)
86th Annual Conference of the DPG and DPG Spring Meeting, 20.-24.03.2023, Dresden, Germany
Permalink: https://www.hzdr.de/publications/Publ-38021
Publ.-Id: 38021
Chirality coupling in curvilinear nanoarchitectures
Volkov, O.; Wolf, D.; Pylypovskyi, O.; Kakay, A.; Sheka, D.; Büchner, B.; Faßbender, J.; Lubk, A.; Makarov, D.
Symmetry effects are key building blocks of condensed matter physics as they define not only interactions but also resulting re- sponses for the intrinsic order parameter. Namely, in magnetism geometric curvature governs the appearance of chiral and anisotropic responses [1], that introduce a new toolbox to create artificial chi- ral nanostructures from achiral magnetic materials [2,3]. Here, we demonstrate both theoretically and experimentally the existence of non-local chiral effects in geometrically curved asymmetric permalloy caps with the vortex texture. We find that the equilibrium vortex core obtain bend and curling deformation, that are dependent on the geometric symmetries and magnetic texture parameters.
[1] D. D. Sheka et al., Comm. Phys. 3, 128 (2020).
[2] O. M. Volkov et al., Phys. Rev. Lett, 123, 077201 (2019).
[3] D. Makarov et al., Adv. Mater. 34, 2101758 (2022).
Keywords: Symmetry effects; Cuvilinear magnetism; Magnetic vortex; Micromagnetics
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Lecture (Conference)
86th Annual Conference of the DPG and DPG Spring Meeting, 20.-24.03.2023, Dresden, Germany
Permalink: https://www.hzdr.de/publications/Publ-38020
Publ.-Id: 38020
Steam Line Break Analysis in NuScale SMR with the Coupled System Code ATHLET-DYN3D in the Framework of the EU H2020 McSAFER
Diaz Pescador, E.; Jobst, M.; Grahn, A.; Kliem, S.
The small modular reactor (SMR) NuScale is modelled by Helmholtz-Zentrum Dresden-Rossendorf
(HZDR) in the framework of the EU H2020 McSAFER project. NuScale is a SMR of integral pressurized
water reactor (iPWR) type, operated by light water driven by natural circulation in all operation modes.
This work summarizes the modelling approach of NuScale SMR with the coupled thermalhydraulic/neutronic code ATHLET-DYN3D. The 3-D neutronic calculation is performed with a XS-library
developed with Serpent based on 4-neutron group homogenized nuclear constants for fuel and heavy
reflector. The paper presents results and discussion from a non-isolable double-ended steam line break
(SLB) sequence, based on the Design Certification Application (DCA) report. The simulation results at
steady-state show agreement with the reference values from the DCA report. The transient calculation
shows that both steam generators (SGs) boil-off and the reactor is tripped upon “low main steam pressure”
function. The rapid depressurization and high steam rates towards the break lead to enhanced primary-tosecondary heat removal. However, the reactor symmetry imposed by the arrangement of the two compact
SGs enhances flow mixing and limits coolant temperature reduction at the core inlet, thereby preventing a
power excursion and highlighting the inherent safety of this reactor design. Acceptance criterion is met
regarding pressure increase below acceptable limits inside the intact SG after steam isolation valve closure.
Keywords: NuScale; SMR; ATHLET-DYN3D; SLB; McSAFER
Related publications
-
Steam Line Break Analysis in NuScale SMR with the Coupled System Code …
ROBIS: 37485 has used this (Id 38019) publication of HZDR-primary research data
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Contribution to proceedings
20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20), 20.-25.08.2023, Washington DC, United States of America
Proceedings of NURETH-20
Permalink: https://www.hzdr.de/publications/Publ-38019
Publ.-Id: 38019
Data publication: Ab initio insights on the ultrafast strong-field dynamics of anatase TiO2
Suma Balakrishnan, S. L.; Lokamani, M.; Ramakrishna, K.; Cangi, A.; Murali, D.; Posselt, M.; Assa Aravindh, S.
Data and input scripts of the project "Ab initio insights on the ultrafast strong-field dynamics of anatase TiO2".
Keywords: Density functional theory; Electron dynamics; Quantum systems; Thin films
Related publications
- DOI: 10.48550/arXiv.2306.17554 references this (Id 38018) publication
- DOI: 10.1103/PhysRevB.108.195149 references this (Id 38018) publication
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Ab initio insights on the ultrafast strong-field dynamics of anatase TiO2
ROBIS: 37571 has used this (Id 38018) publication of HZDR-primary research data
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Reseach data in the HZDR data repository RODARE
Publication date: 2023-12-04 Open access
DOI: 10.14278/rodare.2592
Versions: 10.14278/rodare.2593
License: CC-BY-4.0
Downloads
Permalink: https://www.hzdr.de/publications/Publ-38018
Publ.-Id: 38018
Evolution of point defects in pulsed-laser-melted Ge1-xSnx probed by positron annihilation lifetime spectroscopy
Steuer, O.; Liedke, M. O.; Butterling, M.; Schwarz, D.; Schulze, J.; Li, Z.; Wagner, A.; Fischer, I. A.; Hübner, R.; Zhou, S.; Helm, M.; Cuniberti, G.; Georgiev, Y.; Prucnal, S.
Direct-band-gap Germanium-Tin alloys (Ge1-xSnx) with high carrier mobilities are promising materials for nano- and optoelectronics. The concentration of open volume defects in the alloy, such as Sn and Ge vacancies, influences the final device performance. In this article, we present an evaluation of the point defects in molecular-beam-epitaxy grown Ge1-xSnx films treated by post-growth nanosecond-range pulsed laser melting (PLM). Doppler broadening – variable energy positron annihilation spectroscopy and variable energy positron annihilation lifetime spectroscopy are used to investigate the defect nanostructure in the Ge1-xSnx films exposed to increasing laser energy density. The experimental results, supported with ATomic SUPerposition calculations, evidence that after PLM, the average size of the open volume defects increases, which represents a raise in concentration of vacancy agglomerations, but the overall defect density is reduced as a function of the PLM fluence. At the same time, the positron annihilation spectroscopy analysis provides information about dislocations and Ge vacancies decorated by Sn atoms. Moreover, it is shown that the PLM reduces the strain in the layer, while dislocations are responsible for trapping of Sn and formation of small Sn-rich-clusters.
Related publications
- DOI: 10.17815/jlsrf-2-58 is cited by this (Id 38017) publication
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 38017) publication
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Journal of Physics: Condensed Matter 36(2023), 085701
DOI: 10.1088/1361-648X/ad0a10
Permalink: https://www.hzdr.de/publications/Publ-38017
Publ.-Id: 38017
Non-local chirality breaking in curvilinear nanoarchitectures
Volkov, O.; Wolf, D.; Pylypovskyi, O.; Kakay, A.; Sheka, D.; Büchner, B.; Faßbender, J.; Lubk, A.; Makarov, D.
Symmetry effects are fundamental in condensed matter physics as they define not only interactions but also resulting responses for the intrinsic order parameter depending on its transformation properties with respect to the operations of space and time reversal. Magnetic materials or layer stacks with structural space inversion symmetry breaking obtained much research attention due to the appearance of chiral Dzyaloshinskii-Moriya interaction (DMI) [1,2]. The latter manifests itself in the formation of non-trivial chiral and topological spin textures (e.g. skyrmions, bubbles, homochiral spirals and domain walls), that are envisioned to be utilized for prospective spintronic devices. At present, tailoring magnetochirality is done by the selection of materials and adjustment of their composition. Alternatively, space inversion symmetry breaking of the magnetic order parameter appears in geometrically curved systems [3]. In curvilinear ferromagnets, curvature governs the appearance of geometry-induced chiral and anisotropic responses, which introduce a new toolbox to create artificial chiral nanostructures from achiral magnetic materials suitable for the stabilization of non-trivial chiral textures [4,5].
Recently, much attention was dedicated to the exchange interaction, which enables curvature-induced extrinsic DMI as was proposed theoretically and validated experimentally for the case of conventional achiral magnetic materials [6]. Here, we demonstrate the existence of non-local chiral effects in geometrically curved asymmetric permalloy cap with the vortex texture. Using the full-scale simulation of the asymmetric nanodots we study how the vortex texture is changing with respect to the introduced sample asymmetry. We find that the equilibrium vortex core obtain both bend and curling deformation, that are dependent on the geometric symmetries and magnetic parameters. We relate the observed changes in the vortex string to the non-local chiral effects, that arise from the asymmetry of the top and bottom surfaces and existence of both in- and out-of-plane magnetization components of different parity with respect to the reflection procedure [5]. The obtained micromagnetic results were confirmed by magnetic imaging using transmission electron microscopy based electron holography for the asymmetric permalloy cap. These results will be discussed in the talk.
[1] I. Dzyaloshinsky, J. Phys. Chem. Solids 4 (1958), 241.
[2] T. Moriya, Phys. Rev. Lett. 4 (1960), 228.
[3] R. Hertel, SPIN 3 (2013), 1340009.
[4] D. Makarov, et al., Adv. Mater. 34 (2021), 2101758.
[5] D. D. Sheka, et al., Commun. Phys. 3 (2020), 128.
[6] O. M. Volkov, et al., Phys. Rev. Lett. 123 (2019), 077201.
Keywords: Symmetry effects; Non-local chirality breaking; Magnetic vortex; Micromagnetics
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Lecture (Conference)
4th IEEE International Conference on Advances in Magnetics, IEEE AIM 2023, 16.-21.01.2023, Moena, Italy
Permalink: https://www.hzdr.de/publications/Publ-38016
Publ.-Id: 38016
IAEA’s Coordinated Research Projects on Thermal Hydraulics of Fast Reactors
Morelová, N.; Kriventsev, V.; Sumner, T.; Moisseytsev, A.; Heidet, F.; Wootan, D. W.; Casella, A. M.; Nelson, J. V.; Piazza, I. D.; Hassan, H.; Lorusso, P.; Martelli, D.; Yang, X.; Wang, J.; Lu, D.; Zhang, D.; Gerschenfeld, A.; Kliem, S.; Fridman, E.; Rineiski, A.; Kumaresan, N.; Giannetti, F.; Petruzzi, A.; Tanaka, M.; Jeong, J.-H.; Hong, J.; Stempniewicz, M.; Tsaun, S.; Volkov, A.; Wallenius, J.; Fiorina, C.; Mikityuk, K.; Vaghetto, R.; Omotowa, O.; Kelly, J.; Lane, J.
A Coordinated Research Project on “Benchmark Analysis of FFTF Loss of Flow Without Scram Test” was launched by the International Atomic Energy Agency (IAEA) in 2018. A series of passive safety tests were conducted from 1980-1992 at the Fast Flux Test Facility (FFTF), 400 MW(th) liquid sodium cooled nuclear test reactor owned by U.S. Department of Energy (DOE) to demonstrate the potential of FFTF to survive severe accident initiators with no core damage. Amongst these tests was a series of Loss of Flow Without Scram (LOFWOS) tests from power levels up to 50%, also commonly referred to as Unprotected Loss of Flow (ULOF) tests, which were studied in the IAEA CRP. The data were provided by the Argonne National Laboratory (ANL) and Pacific Northwest National Laboratory (PNNL).
Another Research Coordinated Project on “Benchmark of Transition from Forced to Natural Circulation Experiment with Heavy Liquid Metal Loop” was launched by the IAEA in 2022. Three tests were conducted in 2017 to study the thermal-hydraulic behavior of a test fuel assembly cooled by lead-bismuth eutectic alloy during transition from forced to natural convection at the NACIE-UP facility at Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Italy. This project is the first IAEA CRP that is dedicated to the thermal hydraulics of lead and lead bismuth eutectic (LBE) technology.
The paper provides a general overview of the two CRPs within the framework of the IAEA activities on thermal hydraulics of fast reactors.
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Contribution to proceedings
30th International Conference on Nuclear Engineering (ICONE30), 21.-26.05.2023, Kyoto, Japan
DOI: 10.1299/jsmeicone.2023.30.1632
Permalink: https://www.hzdr.de/publications/Publ-38015
Publ.-Id: 38015
Intrusion tip velocity controls the emplacement mechanism of sheet intrusions
Köpping, J.; Cruden, A. R.; Thiele, S. T.; Magee, C.; Bunger, A.
Space for intruding magma is created by elastic, viscous, and/or plastic deformation of
host rocks. Such deformation impacts the geometries of igneous intrusions, particularly
sills and dikes. For example, tapered intrusion tips indicate linear-elastic fracturing during
emplacement, whereas fluidization of host rocks has been linked to development of elongate
magma fingers with rounded tips. Although host rock fluidization has only been observed at
the lateral tips of magma fingers, it is assumed to occur at their leading edges (frontal tips)
and thereby control their propagation and geometry. Here, we present macro- and micro-
structural evidence of fluidized sedimentary host rock at the lateral tips of magma fingers
emanating from the Shonkin Sag laccolith (Montana, western United States), and we explore
whether fluidization could have occurred at their frontal tips. Specifically, we combine heat
diffusion modeling and fracture tip velocity estimates to show that: (1) low intrusion tip ve-
locities (≤10−5 m s−1) allow pore fluids ahead of the intrusion to reach temperatures sufficient
to cause fluidization, but (2) when tip velocities are high (∼0.01–1 m s−1), which is typical for
many sheet intrusions, fluidization ahead of propagating tips is inhibited. Our results suggest
that intrusion tip velocity (i.e., strain rate) is a first-order control on how rocks accommodate
magma. Spatially and temporally varying velocities of lateral and frontal tips suggest that
deformation mechanisms at these sites may be decoupled, meaning magma finger formation
may not require host rock fluidization. It is thus critical to consider strain rate and three-
dimensional intrusion geometry when inferring dominant magma emplacement mechanisms.
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Geology (2023)
Online First (2023) DOI: 10.1130/G51509.1
Permalink: https://www.hzdr.de/publications/Publ-38011
Publ.-Id: 38011
Data publication: Portable Droplet-Based Real-Time Monitoring of Pancreatic α-Amylase in Postoperative Patients
Zhao, X.; Kolbinger, F. R.; Distler, M.; Weitz, J.; Makarov, D.; Bachmann, M.; Baraban, L.
research data on amylase concentration detection (Pancreatic α-Amylase in Postoperative Patients) with millifluidic device and plate reader and their statistical analysis
Keywords: pancreatic surgery; postoperative pancreatic fistula; pancreatic α-amylase; droplet-based millifluidics; point-of-care diagnostics
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Reseach data in the HZDR data repository RODARE
Publication date: 2023-12-01 Open access
DOI: 10.14278/rodare.2587
Versions: 10.14278/rodare.2588
License: CC-BY-4.0
Downloads
Permalink: https://www.hzdr.de/publications/Publ-38005
Publ.-Id: 38005
Where I am – Chemical microscopy of Eu(III)
Steudtner, R.; Klotzsche, M.; Vogel, M.; Stadler, J.; Drobot, B.
Linking microscopy and spectroscopy based on the correlative application of state of the art spectroscopic, microscopic and biochemical methods and equipment is inevitable in the modern time of f-element biochemistry. The aim of this work was the direct visualization and localization in combination with the chemical identification and characterization of f-elements, here Eu(III), interacting with biostructures.
Herein, we utilized chemical microscopy – a combination of light microscopy and high resolution luminescence spectroscopy [1] – in order to spatially resolve the Eu(III) species distribution in an artificial natural sample. In this proof-of-concept study, a ternary system consisting of Eu(III), calcite and the metal reducing bacterium Shewanella oneidensis MR-1 was employed to confirm the applicability of chemical microscopy for environmental samples. Subsequent luminescence spectroscopic mapping and data deconvolution by the means of non-negative iterative factor analysis (NIFA) [2] resulted in three distinct signal sets: one Raman (pure calcite) and two Eu(III) emission spectra. Luminescence species assigned to Eu(III), on the one hand, that has been complexed with biofilm extracellular DNA (magenta-colored - Figure 1) and, on the other hand, protein bonded Eu(III), depicted in green. These findings emphasize the strength of the described analytical technique and open the field for further studies applying Eu(III) as molecular probe in order to understand complex interaction pathways of lanthanides in the environment. The utilization of Eu(III) as a luminescent probe for chemical microscopy additionally revealed the microscopic distribution of the Eu(III) in roots, root cross sections and individual cells presented by several examples.
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Poster
11th International Conference on f-Elements, 22.-26.08.2023, Strasbourg, France
Permalink: https://www.hzdr.de/publications/Publ-38004
Publ.-Id: 38004
Radioökologische Forschung am HZDR – Spannend bis in die Haarspitzen!
Steudtner, R.; Drobot, B.; Cherkouk, A.; Sachs, S.; Raff, J.
In der Umwelt beeinflussen physikalische, chemische und biologische Prozesse das Wanderungsverhalten von langlebigen Radionukliden (RN). Ziel der Forschung der Abteilung Biogeochemie ist es, dominierende Prozesse der Wechselwirkung von Radionukliden in der Biosphäre einschließlich der Nahrungskette zu identifizieren, die Biochemie dieser Prozesse auf molekularer Ebene zu verstehen und ihre Relevanz für Radionuklidmigration und -transfer nicht nur in der Natur, sondern auch im Umfeld eines Endlagers für hochradioaktive Abfälle zuverlässiger abschätzen zu können.
Für den sensitiven Nachweis, die Identifikation des Chemismus sowie der Lokalisation von Radionukliden in verschiedenen biologischen Matrices und aquatischen Systemen nutzen wir eine Vielzahl von spektroskopischen und mikroskopischen Verfahren. Eine zentrale Rolle spielt dabei die Laser-induzierte Anregung der Lumineszenz von Actiniden und Lanthaniden, welche in Verbindung mit hochauflösender Mikroskopie die Beschreibung radioökologischer Prozesse in einer neuen Detailtiefe erlaubt. Mit dieser einzigartigen Kombination konnte zum Beispiel eine Actinid-induzierte Stressantwort bei Pflanzenzellen nachgewiesen, und die chemische Bindungsform von Uran in komplexen Umweltproben analysiert werden. Ein wichtiger Teilaspekt ist dabei außerdem die qualitative und quantitative Erfassung der chemo- und radiotoxischen Wirkung endlagerrelevanter als auch natürlich vorkommender Radionuklide (naturally occuring radioactive materials - NORM) in Organismen und ihre Zellen.
Weitere Arbeiten befassen sich aktuell mit der Fragestellung, wie sich eine Uranbelastung in der Umgebung von Goldminen auf die im Umland lebende Bevölkerung auswirkt. Dazu wird gegenwärtig in einem gemeinsamen Projekt mit dem VKTA und der Wismut GmbH der Schwermetallgehalt in Haarproben von Personen mittels massenspektrometrischer Methoden bestimmt und bewertet, die im Umland von Johannisburg und nahe des weltweit größten Goldvorkommens, der Witwatersrand-Lagerstätte, leben. Beim Abbau des begehrten Edelmetalls gelangt auch gesundheitsschädlicher, giftiger und radioaktiver Bergbauabfall als Nebenprodukt an die Oberfläche.
Die aufgeführten Beispiele belegen eindrücklich, wie wichtig es ist, das Verhalten von Radionukliden in der Umwelt zu erforschen, zu verstehen und vorhersagbar zu machen, um die Bevölkerung und Natur effektiv zu schützen.
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Poster
10. RCA Workshop, 12.-14.06.2023, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-38003
Publ.-Id: 38003
Thermoelectric Magnetohydrodynamic Control in Alloy Solidification
Kao, A.; Fan, X.; Shevchenko, N.; Tonry, C.; Soar, P.; Krastins, I.; Eckert, S.; Pericleous, K.; Lee, P. D.
Magnetic fields have been shown to have a significant effect during solidification in a wide range of conditions from the slow growth of traditional casting to the more rapid growth of Additive Manufacturing. An underlying phenomenon is Thermoelectric Magnetohydrodynamics (TEMHD), which, due to inherent thermal gradients, generate thermoelectric currents and ultimately a Lorentz force through interaction with the magnetic field. In casting this leads to inter-dendritic convective solute transport. This can be used to control freckle defect formation in the GaIn system, where the magnetic field can be used to reposition channel formation, introduce preferential growth of secondary arms, plume migration and complex grain boundary interactions. These mechanisms have been observed by X-ray synchrotron experiments and predicted by TESA (ThermoElectric Solidification Algorithm), a parallel Cellular Automata Lattice Boltzmann based numerical model.
In laser AM, melt pools are subject to large thermal gradients and consequently form relatively large thermoelectric currents. The system is highly dependent on the orientation and strength of the magnetic field with competition between Marangoni flow and TEMHD resulting in control of the depth, width and potential deflections of the melt pool. This leads to significant changes in the microstructure including modification to the melt pool boundary layer and epitaxial growth. The numerical predictions also compare favourably to X-ray synchrotron experiments.
Keywords: Magnetic fields; Alloy solidification; Additive Manufacturing; Thermoelectric Magnetohydrodynamics
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Lecture (Conference)
International scientific colloquium “Modelling for Materials Processing”, 18.-19.09.2023, Riga, Latvia
Permalink: https://www.hzdr.de/publications/Publ-37999
Publ.-Id: 37999
In-situ Measurements of Dendrite Tip Shape Selection in a Metallic Alloy
Neumann-Heyme, H.; Shevchenko, N.; Grenzer, J.; Eckert, K.; Beckermann, C.; Eckert, S.
The size and shape of the primary dendrite tips determine the principal length scale of the microstructure evolving during solidification of alloys. In-situ X-ray measurements of the tip shape in metals have been unsuccessful so far due to insufficient spatial resolution or high image noise. To overcome these limitations, high-resolution synchrotron radiography and advanced image processing techniques are applied to a thin sample of a solidifying Ga-35wt.%In alloy, as shown in Figure 1. Quantitative in-situ measurements are performed of the growth of dendrite tips during the fast initial transient and the subsequent steady growth period, with tip velocities ranging over almost two orders of magnitude. As shown in Figure 2, the value of the dendrite tip shape selection parameter is found to be σ^*=0.0768. According to microscopic solvability theory, this value suggests an interface energy anisotropy of ε_4=0.015 for the present Ga-In alloy. The non-axisymmetric dendrite tip shape amplitude coefficient is measured to be A_4≈0.004, which is in excellent agreement with the universal value previously established for dendrites.
Keywords: dendrite tip; In-situ Measurements; Ga - In alloys; Interface energy anisotropy
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Invited lecture (Conferences)
TMS 2023 Frontiers in Solidification: An MPMD Symposium Honoring Jonathan A. Dantzig, 19.-23.03.2023, San Diego, California, USA
Permalink: https://www.hzdr.de/publications/Publ-37998
Publ.-Id: 37998
The impact of melt flow on solidification patterns in a ternary Ga-In-Bi alloy
Shevchenko, N.; Budenkova, O.; Chichignoud, G.; Eckert, S.
In situ X-ray observations are scarce for ternary and multi-component alloys. A Ga-In-Bi alloy is solidified in a Hele-Shaw cell under buoyancy-driven convection. A complex and strongly disoriented dendrite-type solid phase is formed that differs from a regular dendrite network. It is shown that primary arms of dendrites in a ternary system adapt their velocity to the local concentration ahead of their tips and change continuously or abruptly the growth direction. Some grains exhibit a morphology that is rather similar to the "seaweed" pattern. The appearance of seaweed grains is usually related to a solid/liquid interfacial energy. Further, we focus on the role of melt flow in transition from dendritic arrays to seaweed structures. In particular, it is shown that the splitting of a dendrite tip is preceded by the oscillation of the local intensity of the X-ray pattern which is related to the local concentration of the components.
Keywords: Ternary alloy; in situ X-ray imaging; solidification; seaweed pattern; melt convection
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Lecture (Conference)
TMS 2023 Frontiers in Solidification: An MPMD Symposium Honoring Jonathan A. Dantzig, 19.-23.03.2023, San Diego, California, USA
Permalink: https://www.hzdr.de/publications/Publ-37997
Publ.-Id: 37997
Momentum spectrum of Schwinger pair production in four-dimensional e-dipole fields
Degli Esposti, G.; Torgrimsson, G.
We calculate the momentum spectrum of electron-positron pairs created via the Schwinger mechanism by a class of four-dimensional electromagnetic fields called e-dipole fields. To the best of our knowledge, this is the first time the momentum spectrum has been calculated for 4D, exact solutions to Maxwell’s equations. Moreover, these solutions give fields that are optimally focused, and are hence particularly relevant for future experiments. To achieve this we have developed a worldline instanton formalism where we separate the process into a formation and an acceleration region.
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Contribution to WWW
https://arxiv.org/pdf/2308.01659.pdf
Permalink: https://www.hzdr.de/publications/Publ-37992
Publ.-Id: 37992
Efficient Near-Infrared Light-Emitting Diodes Based on CdHgSe Nanoplatelets
Prudnikau, A.; Roshan, H.; Paulus, F.; Martín-García, B.; Hübner, R.; Bahmani Jalali, H.; de Franco, M.; Prato, M.; Di Stasio, F.; Lesnyak, V.
Cadmium mercury selenide (CdHgSe) nanocrystals exhibit a unique combination of low-energy optical absorption and emission, which can be tuned from the visible to the infrared range through both quantum confinement and adjustment of their composition. Owing to this advantage, such nanocrystals have been studied as a promising narrow-band infrared light emitter. However, the electroluminescence of CdHgSe-based nanocrystals has remained largely unexplored, despite their potential for emitting light in the telecom wavelength range. Further benefits to their optical properties are expected from their shape control, in particular the formation of 2D nanocrystals, as well as from a proper design of their heterostructures. In this work, a colloidal synthesis of CdHgSe/ZnCdS core/shell nanoplatelets (NPLs) starting from CdSe template NPLs employing a cation exchange strategy is developed. The heterostructures synthesized exhibit photoluminescence that can be tuned from ≈1300 to 1500 nm. These near-infrared-active NPLs are employed in light-emitting diodes, demonstrating low turn-on voltage and high external quantum efficiency.
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 37991) publication
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Advanced Functional Materials (2023), 2310067
Online First (2023) DOI: 10.1002/adfm.202310067
Permalink: https://www.hzdr.de/publications/Publ-37991
Publ.-Id: 37991
Effects of a horizontal magnetic field on the cross-sectional distribution of gas bubbles chain rising in a gallium alloy
Murakawa, H.; Maeda, S.; Eckert, S.
Understanding the behavior of rising bubbles in a liquid metal under the influence of a magnetic field (MF) is
crucial for optimizing continuous casting processes. The study experimentally investigated the effects of a hor-
izontal MF on the behavior of bubble chains in a gallium alloy. High-speed ultrasonic computed tomography was
used to measure the instantaneous bubble crossing positions in a cylindrical column with an inner diameter of 50
mm. With an increase in the MF strength, the oscillations of the bubbles were suppressed, resulting in the
crossing position being concentrated in a certain area of the cross-section. The fluctuations in the time intervals
of the chain bubbles decreased. These effects were more pronounced when the magnetic interaction parameter
(or Stuart number) was greater than 1. The distribution of bubbles in the direction perpendicular to the MF was
widespread slightly compared to that in the direction parallel to the MF; this was noticeable at higher flow rates.
The suppression of the wake turbulence induced by the Lorentz force was larger in the direction parallel to the
MF than that in the direction perpendicular to the MF. Our results have the potential to be used for the direct
verification of numerical models.
Keywords: liquid metal; bubbly flow; magnetic field; high-speed ultrasonic computed tomography
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International Journal of Multiphase Flow 170(2024), 104649
Online First (2023) DOI: 10.1016/j.ijmultiphaseflow.2023.104649
Downloads
- Secondary publication expected from 31.10.2024
Permalink: https://www.hzdr.de/publications/Publ-37988
Publ.-Id: 37988
Vibrations Analysis of Bubble Evolution in Liquids of Varying Physical Properties
Rigas, K.; Willers, B.; Eckert, S.; Glaser, B.
In recent years there is an attempt to control the gas stirring intensity in metal-making ladles with the aid of vibration measurements. Understanding better the induced vibrations in two-phase flows can substantially improve the existing models for gas stirring control. In this work, highly sensitive accelerometers were used for the vibration measurements in a liquid metal alloy; Sn–40 wt pctBi alloy at 200 °C and water at 20 °C. The examination of the liquids was conducted in the ladle mockup integrated into the Liquid Metal Model for Steel Casting facility at Helmholtz-Zentrum Dresden Rossendorf. Single bubbles were generated in the respective
liquids by controlled argon injection at low flow rates in the range of 0.01 to 0.15 NL/min through a single nozzle installed at the bottom of the ladle. Obtained results demonstrate differences between the induced vibrations in the examined liquids in terms of the magnitude of the root mean square values of vibration amplitude and the shape of the resulting curves with increasing flow rate. Furthermore, continuous wavelet transform reveals variations in the duration and vibrational frequency of the evolved bubble phenomena. The findings suggest that
differences in the physical properties of the examined liquids result in variations in the vibrations induced during bubble evolution.
Keywords: steel ladle; gas stirring; bubbly flow; vibration measurements
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Metallurgical and Materials Transactions B (2023)
Online First (2023) DOI: 10.1007/s11663-023-02953-8
Permalink: https://www.hzdr.de/publications/Publ-37987
Publ.-Id: 37987
New Insights in Controlling Freckle Defect Formation using Magnetic Fields
Fan, X.; Shevchenko, N.; Tonry, C.; Clark, S. J.; Atwood, R. C.; Eckert, S.; Pericleous, K.; Lee, P. D.; Kao, A.
Static magnetic fields have been shown to have a significant effect on channel formation in the GaIn freckle defect forming alloy. Inter-dendritic convective solute transport driven by the Thermoelectric Magnetoydrodynamics (TEMHD) phenomena leads to repositioning of the channel, preferential growth of secondary arms, plume migration and complex grain boundary interactions. This paper focuses on a secondary TEMHD mechanism that is generated by larger scale thermoelectric currents that circulate between the liquid and the entire mushy zone. This secondary mechanism is strongly dependent on the thermal profile and this leads to further modification of the bulk flow and ultimately plume migration. This mechanism has been observed by Xray synchrotron experiments and predicted by TESA (ThermoElectric Solidification Algorithm), a parallel Cellular Automata Lattice Boltzmann based numerical model, providing new insights into the intimate coupling between thermal solidification conditions and the effect of the magnetic field.
Keywords: Static magnetic fields; Solidification; Thermoelectric Magnetoydrodynamics; Freckle defect; Ga-In alloys
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Lecture (Conference)
TMS 2023 Frontiers in Solidification: An MPMD Symposium Honoring Jonathan A. Dantzig, 19.-23.03.2023, San Diego, California, USA
Permalink: https://www.hzdr.de/publications/Publ-37986
Publ.-Id: 37986
Manipulation of Encapsulated Plasmons in Solids for Photonic Applications
Li, R.; Pang, C.; Sun, X.; Jamshidi, K.; Zhou, S.; Chen, F.
Plasmonics offers a promising framework for next-generation photonic applications, including optical tweezers, ultrafast lasing, and quantum communication. Integrating plasmonics into photonics enables efficient interface coupling between heterogeneous systems, resulting in enhanced performance and diverse functionality. This review presents various unique encapsulation methods for developing plasmonics-embedded hybrid nanocomposite systems. Recent progress in the manipulation mechanisms of encapsulated plasmons is systematically summarized, offering an active modulation platform for optimizing optical performance. Considering the opportunities and challenges, the advancement of tunable encapsulated plasmons exhibits promising prospects, as demonstrated by a section discussing recent significant progress in photonic applications.
Keywords: Plasmonics; Nanostructures; Ion implantation; Optical tailoring; Integrated photonic application
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 37983) publication
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Fundamental Research (2023)
Online First (2023) DOI: 10.1016/j.fmre.2023.10.002
Permalink: https://www.hzdr.de/publications/Publ-37983
Publ.-Id: 37983
Fine-tuning of plasmonics by Au@AuY/Au core-shell nanoparticle monolayer for enhancement of third-order nonlinearity
Yong, L.; Pang, C.; Amekura, H.; Schumann, T.; Peng, L.; Zhixian, W.; Haocheng, L.; Li, R.
The manipulation of plasmonics on noble metal nanoparticles (NPs) is of great interest in developing nonlinear photonic devices, such as all-optical switches and frequency combs. An Au@AuY-core/Au-shell nanoparticle (Au@AuY/Au NP) monolayer is proposed for the fine-tuning of plasmonics and enhanced third-order nonlinearity. Based on the different thermodynamic mechanisms of Au and Y ions, the compact Au@AuY/Au core–shell architectures are designed and surface-modified in fused silica (SiO2) with enhanced free electron density, mobility, and quantum size effect. The flexible modulation of plasmonics is realized, resulting in significant absorption enhancement (165% for interband absorption and 38% for free electron absorption, respectively) and fine-tuning of the localized surface plasma resonance (LSPR) band. In addition, the physical mechanism is investigated by density functional theory (DFT) and Mie theory, which reveals a transition from size-independence to size-dependence of LSPR owing to the synergistic effect of multiple physical factors such as free electron density and mobility. With the above advantages, the third-order nonlinearity is enhanced by 4.4 times compared with traditional Au NPs. It indicates the significant potential of Au@AuY/Au core–shell NP monolayer in the performance improvement of nonlinear photonic devices.
Keywords: Plasmonics; Core-shell alloy nanostructure; Localized surface plasmon resonance; Third-order nonlinearity; Sequential ion implantation
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 37980) publication
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Applied Surface Science 631(2023), 157582
Online First (2023) DOI: 10.1016/j.apsusc.2023.157582
Permalink: https://www.hzdr.de/publications/Publ-37980
Publ.-Id: 37980
Data publication: Piezostrain as a Local Handle to Control Gyrotropic Dynamics of Magnetic Vortices
Iurchuk, V.; Sorokin, S.; Faßbender, J.; Lindner, J.; Kakay, A.
The archive contains the experimental (MR and EDFMR) and simulated (mumax3) data related to the publication "Piezostrain as a Local Handle to Control Gyrotropic Dynamics of Magnetic Vortices" (Physical Review Applied 20(2023), 024080).
Related publications
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Piezostrain as a Local Handle to Control Gyrotropic Dynamics of Magnetic …
ROBIS: 37975 has used this (Id 37978) publication of HZDR-primary research data
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Reseach data in the HZDR data repository RODARE
Publication date: 2023-11-29 Open access
DOI: 10.14278/rodare.2583
Versions: 10.14278/rodare.2584
License: CC-BY-4.0
Downloads
Permalink: https://www.hzdr.de/publications/Publ-37978
Publ.-Id: 37978
Software: removal of bremsstrahlung background from SAXS signals with deep neural networks
Software for training and inference of neural network models to remove bremsstrahlung background from SAXS imaging data obtained at the European XFEL laboratory.
We thank Peter Steinbach for providing the codebase for the equivariant UNet, which we integrated into our repository.
Keywords: SAXS; XFEL; equivariant neural networks; noise removal
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Software in the HZDR data repository RODARE
Publication date: 2023-11-29 Closed access
DOI: 10.14278/rodare.2585
Versions: 10.14278/rodare.2586
Downloads
Permalink: https://www.hzdr.de/publications/Publ-37977
Publ.-Id: 37977
Near-infrared photodetectors based on single germanium nanowires
Echresh, A.; Shaikh, M. S.; Helm, M.; Erbe, A.; Berencen, Y.; Rebohle, L.; Georgiev, Y.
Germanium (Ge) is a promising candidate for designing near-infrared photodetectors because of its bandgap (0.66 eV), which induces a large absorption coefficient at near-infrared wavelengths. Also, Ge has excellent compatibility of parallel processing with silicon technology [1,2]. Photodetectors based on Ge material have been fabricated with different structures such as metal-semiconductor-metal (MSM) and p−n junctions. On the other hand, the observation of high responsivity in semiconductor nanowires with a high surface-to-volume ratio has attracted growing interest in using nanowires in photodetectors. So far, significant efforts have been made to fabricate single nanowire-based photodetectors with different materials such as Si, Ge, and GaN to achieve miniaturized devices with high responsivity and short response time [3-5]. Hence, Ge nanowires are an excellent candidate to fabricate single nanowire-based near-infrared photodetectors.
In this work, we report on the fabrication and characterization of an axial p−n junction along Ge nanowires. First, through a resist mask created by electron beam lithography (EBL), the top Ge layers of germanium-on-insulator (GeOI) substrates were locally doped with phosphorus ions using ion beam implantation followed by rear-side flash lamp annealing. Then, the single Ge nanowire-based photodetectors containing an axial p−n junction were fabricated using EBL and inductively coupled plasma reactive ion etching. The fabricated single Ge nanowire devices demonstrate the rectifying current−voltage characteristic of a p−n diode in dark conditions. Moreover, the photoresponse of the axial p−n junction-based photodetectors was investigated under light illumination with three different wavelengths: 637 nm, 785 nm, and 1550 nm. The measurements indicated that the fabricated photodetectors can be operated at zero bias and room temperature under ambient conditions. A high responsivity of 3.7×102 AW-1 and a detectivity of 1.9×1013 cmHz1/2W-1 were observed at zero bias under illumination of a 785 nm laser diode. The responsivity of the single Ge NW photodetectors was increased by applying a reverse bias of 1V.
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 37976) publication
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Lecture (Conference)
Micro and Nano Engineering (MNE) conference, 25.-28.09.2023, Berlin, Germany
Permalink: https://www.hzdr.de/publications/Publ-37976
Publ.-Id: 37976
Piezostrain as a Local Handle to Control Gyrotropic Dynamics of Magnetic Vortices
Iurchuk, V.; Sorokin, S.; Lindner, J.; Faßbender, J.; Kakay, A.
We present a study of the piezostrain-tunable gyrotropic dynamics in Co40Fe40B20 vortex microstructures fabricated on a 0.7Pb[Mg1/3Nb2/3]O3-0.3PbTiO3 single-crystal substrate. Using field-modulated-spin-rectification measurements, we demonstrate large frequency tunability (up to 45%) in individual microdisks accessed locally with low surface voltages, and magnetoresistive readout. With increased voltage applied to the substrate, we observe a gradual decrease of the vortex-core gyrotropic frequency associated with the contribution of the strain-induced magnetoelastic energy. The frequency tunability strongly depends on the disk size, with increased frequency downshift for disks with larger diameter. Micromagnetic simulations suggest that the observed size effects originate from the joint action of the strain-induced magnetoelastic and demagnetizing energies in large magnetic disks. These results enable a selective energy-efficient tuning of the vortex gyrotropic frequency in individual vortex-based oscillators with all-electrical operation.
Keywords: Magnetic vortices; Magnetoelastic effect; Magnetoresistance; Spin dynamics
Related publications
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Data publication: Piezostrain as a Local Handle to Control Gyrotropic Dynamics …
ROBIS: 37978 HZDR-primary research data are used by this (Id 37975) publication -
Data publication: Piezostrain as a Local Handle to Control Gyrotropic Dynamics …
RODARE: 2584 HZDR-primary research data are used by this (Id 37975) publication
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Physical Review Applied 20(2023), 024080
DOI: 10.1103/PhysRevApplied.20.024080
arXiv: 2305.10056v1
Downloads
- Open Access Version from arxiv.org
- Secondary publication expected from 31.08.2024
Permalink: https://www.hzdr.de/publications/Publ-37975
Publ.-Id: 37975
Probing shock dynamics inside micro-wire targets after high-intensity laser irradiation using small angle x-ray scattering of a free-electron laser
Kluge, T.; Bussmann, M.; Galtier, E.; Glenzer, S.; Grenzer, J.; Gutt, C.; Hartley, N. J.; Huang, L.; Laso García, A.; Ja Lee, H.; McBride, E. E.; Metzkes-Ng, J.; Nakatsutsumi, M.; Nam, I.; Pelka, A.; Prencipe, I.; Randolph, L.; Rehwald, M.; Rödel, C.; Rödel, M.; Toncian, T.; Yang, L.; Zeil, K.; Schramm, U.; Cowan, T.
In this paper, we present an experiment that explores the plasma dynamics of a 7 μm diameter carbon wire after being irradiated with a near-relativistic-intensity short pulse laser. Using an x-ray free electron laser pulse to measure the small angle x-ray scattering signal, we observe that the scattering surface is bent and prone to instability over tens of picoseconds. The dynamics of this process are consistent with the presence of a sharp, propagating shock front inside the wire, moving at a speed close to the hole boring velocity or that expected from a thermal shock at a few tens of Mbar.
Keywords: plasma; SAXS; XFEL; laser; proton acceleration
Related publications
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Raw data for: Probing shock dynamics inside micro-wire targets after …
ROBIS: 36509 HZDR-primary research data are used by this (Id 37974) publication -
Raw data for: Probing shock dynamics inside micro-wire targets after …
RODARE: 2146 HZDR-primary research data are used by this (Id 37974) publication
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New Journal of Physics 25(2023), 103036
DOI: 10.1088/1367-2630/acfab5
Permalink: https://www.hzdr.de/publications/Publ-37974
Publ.-Id: 37974
AND-Targeting of EpCAM+ and CEA+ colorectal cells using the modular Dual-RevCAR platform
González Soto, K. E.; Rodrigues Loureiro, L. R.; Abken, H.; Momburg, F.; Bachmann, M.; Feldmann, A.
Genetically engineered T cells expressing chimeric antigen receptors (CARs) have shown promising results particularly when targeting tumor associated antigens (TAAs) related to hematological malignancies. However, TAAs are usually expressed to some extend also on healthy tissues leading to on-target/off-tumor effects. To overcome this important safety issue along with improving targeting specificity and efficient killing of tumor escape variants, we adapted our Reverse CAR (RevCAR) system to follow an AND-gate Boolean logic. For that, Dual-RevCAR T cells were designed and armed with (I) a signaling (SIG) RevCAR, that includes the intracellular domain (ICD) of CD3 zeta; and (II) a costimulatory (COS) RevCAR, which contains a domain derived from CD28. Because the extracellular domains of both RevCARs are derived from the La/SS-B nuclear protein, Dual-RevCAR T cells will remain inactive until they encounter matching target modules (RevTMs). The bispecific antibody (bsAb)-like structure of the RevTMs allows their binding to RevCAR molecules and to specific antigens. However, only the simultaneous binding of RevTMs to SIG and COS RevCARs will promote the full activation of the Dual-RevCAR T cells. The epithelial cell adhesion molecule (EpCAM) and the carcinoembryonic antigen (CEA) have become appealing markers due to their overexpression in various solid tumor entities such as colorectal cancer, therefore representing promising target antigens for cancer immunotherapies following such a Dual Targeting CAR approach.
Having this in mind, the aim of this work was to assess the potential therapeutic application of the Dual-RevCAR system to target EpCAM and CEA following an AND-gating approach.
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Poster
TUMOR IMMUNOLOGY MEETS ONCOLOGY (TIMO) XVII 2023, 20.-22.04.2023, Halle, Germany
Permalink: https://www.hzdr.de/publications/Publ-37971
Publ.-Id: 37971
Pulsed Electromagnetic Field Effects on Dendritic Solidification in a Thin Cell
Shevchenko, N.; Bai, Q.; Kao, A.; Eckert, S.
This study aims to investigate how pulsed electromagnetic fields (PEMF) can affect grain refinement and microstructure during the solidification of a model Ga-In alloy. The magnetic system used generates field intensities of 8 - 11 mT and frequencies in the domain between 10 and 300 Hz, a duty cycle of 50%. We record the dendritic structures at the end of solidification experiments after switching OFF the electromagnetic field via X-ray radiographic imaging. Preliminary lab-scale results show that the solidification under frequencies above 100 Hz leads to dendrite fragmentation and solute redistribution in the mushy zone. No evidence of a CET is observed despite numerous fragmentation events. The fragments that detached from the dendritic network were unable to grow as equiaxed dendrites in the liquid as they became trapped within the dendritic network.
Keywords: Solidification; X-ray radiography; Dendrite fragmentation; Ga - In alloys; Pulsed electromagnetic fields
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Lecture (Conference)
International scientific colloquium “Modelling for Materials Processing”, 18.-19.09.2023, Riga, Latvia -
Contribution to proceedings
International Scientific Colloquium "Modelling for Materials Processing", 18.-19.09.2023, Riga, Latvia
Proceedings of the IX International Scientific Colloquium "Modelling for Materials Processing", 70-75
Permalink: https://www.hzdr.de/publications/Publ-37970
Publ.-Id: 37970
Visualisation of flow effects in liquid and solidified metals
Shevchenko, N.; Lappan, T.; Eckert, S.
X-ray radiographic imaging is an efficient tool for investigating flow phenomena and solidification processes in optically opaque metallic alloys. This contribution is an overview of the latest advances in in-situ radiographic experiments made by the authors, as well as recent applications, including magnetohydrodynamic systems. We investigated a range of phenomena, such as bubble flow in liquid metal under an applied magnetic field, collective bubble dynamics, particle flow in liquid metal channels, and mesoscale solidification of alloys. Radiography measurements in liquid/solidified metal experiments are inevitably performed under adverse conditions of low signal-to-noise ratio, low image contrast, scattering, etc. To extract meaningful information from experimental data we combine both well-known methodology of data processing and our original codes. Examples of image analysis and results of in-situ experiments performed with low melting point alloys are presented and discussed in this contribution. A focus of these experiments is exploring scaled-down representative systems of industrial processes in metallic alloys.
Keywords: X-ray radiographic imaging; flow phenomena; solidification; Ga-In alloys
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Lecture (Conference)
Helmholtz Imaging Conference 2023, 14.-16.06.2023, Hamburg, Germany
Permalink: https://www.hzdr.de/publications/Publ-37969
Publ.-Id: 37969
Understanding electronic correlations in warm dense quantum plasmas
Warm dense matter (WDM)—an extreme state that is characterized by extreme densities and temperatures—
has emerged as one of the most active frontiers in plasma physics and material science. In nature,
WDM occurs in astrophysical objects such as giant planet interiors and brown dwarfs. In addition,
WDM is highly important for cutting-edge technological applications such as inertial confinement
fusion and the discovery of novel materials. In the laboratory, WDM is studied experimentally in
large facilities around the globe, and new techniques have facilitated unprecedented insights. Yet,
the interpretation of these experiments requires a reliable diagnostics based on accurate theoretical
modeling, which is a notoriously difficult task [1].
In this work, I will give an overview of how we can use exact ab-initio path integral Monte Carlo
(PIMC) simulations [2] together with thermal density functional theory (DFT) calculations to get new
insights into the behavior of WDM. Moreover, I will show how switching to the imaginary- time
representation allows us to significantly improve the interpretation of X-ray Thomson scattering
(XRTS) experiments, which are a key diagnostic for WDM [3]. Specifically, I will present a model-
free temperature diagnostic [4] based on the well-known principle of detailed balance, but available
for all wave numbers, and a new idea to directly extract the electron—electron static structure factor
from an XRTS measurement [5]. As an outlook, I will show how new PIMC capabilities will allow
to give us novel insights into electronic correlations in warm dense quantum plasmas, leading to
unprecedented agreement between experiments [6] and theory.
[1] M. Bonitz et al., Physics of Plasmas 27, 042710 (2020)
[2] M. Böhme et al., Physical Review Letters 129, 066402 (2022)
[3] S. Glenzer and R. Redmer, Reviews of Modern Physics 81, 1625 (2009)
[4] T. Dornheim et al., Nature Communications 13, 7911 (2022)
[5] T. Dornheim et al., arXiv:2305.15305 (submitted)
[6] T. Döppner et al., Nature 618, 270-275 (2023)
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Invited lecture (Conferences)
Polish-German WE-Heraeus Seminar & Max Born Symposium, 04.-06.12.2023, Görlitz, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-37967
Publ.-Id: 37967
Molybdenum Chloride Nanostructures with Giant Lattice Distortions Intercalated into Bilayer Graphene
Liu, Q.; Lin, Y.-C.; Kretschmer, S.; Ghorbani Asl, M.; Solís-Fernández, P.; Siao, M.-D.; Chiu, P.-W.; Ago, H.; Krasheninnikov, A.; Suenaga, K.
The nanospace of the van der Waals (vdW) gap between structural units of two-dimensional (2D) materials serves as a platform for growing unusual 2D systems through
intercalation and studying their properties. Various kinds ofmetal chlorides have previously been intercalated for tuning the properties of host layered materials, but the atomic structure of
the intercalants remains still unidentified. In this study, we investigate the atomic structural transformation of molybdenum(V) chloride (MoCl 5 ) after intercalation into
bilayer graphene (BLG). Using scanning transmission electron microscopy, we found that the intercalated material represents MoCl 3 networks, MoCl 2 chains, and Mo 5 Cl 10 rings. Giant lattice distortions and frequent structural transitions occur in the 2D MoCl x that have never been observed in metal chloride systems. The trend of symmetric to nonsymmetric structural
transformations can cause additional charge transfer from BLG to the intercalated MoCl x , as suggested by our density functional theory calculations. Our study deepens the understanding of the behavior of matter in the confined space of the vdW gap in BLG and provides hints at a more efficient tuning of material properties by intercalation for potential applications,
including transparent conductive films, optoelectronics, and energy storage.
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ACS Nano (2023)
Online First (2023) DOI: 10.1021/acsnano.3c06958
Permalink: https://www.hzdr.de/publications/Publ-37966
Publ.-Id: 37966
The role of multiplicative noise in critical dynamics
de Oliveira Silvano, N.; Barci, D. G.
We study the role of multiplicative stochastic processes in the description of the dynamics of an order parameter near a critical point. We study equilibrium as well as out-of-equilibrium properties. By means of a functional formalism, we build the Dynamical Renormalization Group equations for a real scalar order parameter with symmetry, driven by a class of multiplicative stochastic processes with the same symmetry. We compute the flux diagram using a controlled -expansion, up to order. We find that, for dimensions the additive dynamic fixed point is unstable. The flux runs to a multiplicative fixed point driven by a diffusion function, where s the order parameter and is the fixed point value of the multiplicative noise coupling constant. We show that, even though the position of the fixed point depends on the stochastic prescription, the critical exponents do not. Therefore, different dynamics driven by different stochastic prescriptions (such as Itô, Stratonovich, anti-Itô and so on) are in the same universality class.
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Contribution to WWW
https://arxiv.org/abs/2210.11969
DOI: 10.48550/arXiv.2210.11969
arXiv: 2210.11969 -
Physica A: Statistical Mechanics and its Applications 630(2023), 129246
DOI: 10.1016/j.physa.2023.129246
Downloads
Permalink: https://www.hzdr.de/publications/Publ-37965
Publ.-Id: 37965
Flexible, printable and eco-sustainable magnetoelectronics
Composites consisting of magnetic fillers in polymers and elastomers enable new application scenarios in soft robotics [1,2] and reconfigurable actuation [3]. Furthermore, they gave birth to the novel technology of solution processable magnetic field sensors. We demonstrate that printed magnetoelectronics can be stretchable, skin-conformal, capable of detection of low magnetic fields and withstand extreme mechanical deformations [4,5]. We feature the potential of our skin-conformal sensors in augmented reality settings for remote and touchless control of virtual objects, scrolling electronic documents and zooming maps. We put forth technology to realise magnetic field sensors, which can be printed and self-heal upon mechanical damage [6]. This opens exciting perspectives for magnetoelectronics in smart wearables, interactive printed electronics. Moreover, this research motivates further explorations towards the realization of eco-sustainable magnetoelectronics. For the latter, we will discuss biocompatible and biodegradable magneto sensitive devices, which can help to minimise electronic waste and bring magnetoelectronics to new application fields in medical implants and health monitoring.
[1] Y. Liu et al., Responsive magnetic nanocomposites for intelligent shape-morphing microrobots. ACS Nano 17, 8899 (2023).
[2] M. Richter et al., Locally addressable energy efficient actuation of magnetic soft actuator array systems. Advanced Science 2302077 (2023).
[3] M. Ha et al., Reconfigurable magnetic origami actuators with on-board sensing for guided assembly. Advanced Materials 33, 2008751 (2021).
[4] M. Ha et al., Printable and stretchable giant magnetoresistive sensors for highly compliant and skin-conformal electronics. Advanced Materials 33, 2005521 (2021).
[5] E. S. Oliveros Mata et al., Dispenser printed bismuth-based magnetic field sensors with non-saturating large magnetoresistance for touchless interactive surfaces. Adv. Mater. Technol. 7, 2200227 (2022).
[6] R. Xu et al., Self-healable printed magnetic field sensors using alternating magnetic fields. Nature Communications 13, 6587 (2022).
Keywords: flexible magnetic field sensors; shapeable magnetoelectronics; printed magnetoelectronics; soft magnetic composites; Stimuli-responsive materials
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 37964) publication
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Invited lecture (Conferences)
The 34th GCCCD Annual Conference “Chemistry and Chemical Engineering, Sensing the World”, 02.-03.12.2023, Dresden, Germany
Permalink: https://www.hzdr.de/publications/Publ-37964
Publ.-Id: 37964
Electron holographic mapping of structural reconstruction at mono- and bilayer steps of h-BN
Subakti, S.; Daqiqshirazi, M.; Wolf, D.; Linck, M.; Kern, F. L.; Jain, M.; Kretschmer, S.; Krasheninnikov, A.; Brumme, T.; Lubk, A.
Here, by making use of medium and high resolution autocorrected off-axis electron holography, we directly probe the electrostatic potential as well as in-plane structural reconstruction at edges and steps in multilayer hexagonal boron nitride. In combination with ab initio calculations, the data allows revealing the formation of folded zigzag edges at steps comprising two monolayers and their absence at monolayer steps.
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Physical Review Research 5(2023), 033137
DOI: 10.1103/PhysRevResearch.5.033137
Permalink: https://www.hzdr.de/publications/Publ-37962
Publ.-Id: 37962
Measurement and Simulation of Ultra-Low-Energy Ion–Solid Interaction Dynamics
Titze, M.; Poplawsky, J. D.; Kretschmer, S.; Krasheninnikov, A.; Doyle, B. L.; Bielejec, E. S.; Hobler, G.; Belianinov, A.
Ion implantation is a key capability for the semiconductor industry. As devices shrink, novel materials enter the manufacturing line, and quantum technologies transition to being more mainstream. Traditional implantation methods fall short in terms of energy, ion species, and positional precision. Here, we demonstrate 1 keV focused ion beam Au implantation into Si and validate the results via atom probe tomography. We show the Au implant depth at 1 keV is 0.8 nm and that identical results for low-energy ion implants can be achieved by either lowering the column voltage or decelerating ions using bias while maintaining a sub-micron beam focus. We compare
our experimental results to static calculations using SRIM and dynamic calculations using binary collision approximation codes TRIDYN and IMSIL. A large discrepancy between the static and dynamic simulation is found, which is due to lattice enrichment with high-stopping-power Au and surface sputtering. Additionally, we demonstrate how model details are particularly important to the simulation of these low-energy heavy-ion implantations. Finally, we discuss how our results pave a way towards much lower implantation energies while maintaining high spatial resolution.
Keywords: focused ion beam; ion implantation; ultra-low energy
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Micromachines 14(2023), 1884
DOI: 10.3390/mi14101884
Permalink: https://www.hzdr.de/publications/Publ-37961
Publ.-Id: 37961
58 DERA Rohstoffinformationen Abschlussbericht Dialogplattform Recyclingrohstoffe
Raatz, S.; Deutsche Rohstoffagentur; Deutsche Akademie der Technikwissenschaften; (Editors)
Der Industriestandort Deutschland ist auf eine sichere und nachhaltige Versorgung mit mineralischen Rohstoffen angewiesen. Hierbei wird das Recycling von Rohstoffen als weiteres Standbein der Versorgung neben der heimischen Rohstoffgewinnung und dem Import von Rohstoffen künftig eine immer wichtigere Rolle spielen. In diesem Zusammenhang veröffentlichte das Bundesministerium für Wirtschaft und Klimaschutz (BMWK) im Januar 2023 das Eckpunktepapier „Wege zu einer nachhaltigen und resilienten Rohstoffversorgung“ und unterstrich darin die strategische Bedeutung einer engen Verzahnung von Kreislaufwirtschafts- und Rohstoffstrategie.
Die Dialogplattform Recyclingrohstoffe wurde im Rahmen der Deutschen Rohstoffstrategie 2020 mit dem Ziel beauftragt, Maßnahmen zu erarbeiten, die den Beitrag von Recyclingrohstoffen (Sekundärrohstoffen) für die Versorgungssicherheit von Metallen und Industriemineralen stärken.
Hierzu wurden in einem Dialogprozess mit über 380 Vertreterinnen und Vertretern aus Wirtschaft, Wissenschaft und Verwaltung sowie Zivilgesellschaft über einen Zeitraum von zwei Jahren in zwei Arbeitskreisen (Metalle und Industrieminerale) mit insgesamt acht Unterarbeitskreisen konkrete Handlungsoptionen entwickelt. Der inhaltliche Zuschnitt der Unterarbeitskreise orientierte sich an spezifischen Stoffströmen, die zum Beispiel aufgrund ihrer Mengenrelevanz, Kritikalität oder ihres Beitrags zu Treibhausgasemissionen von besonderer Relevanz sind und stoffstromspezifische Anforderungen an das Recycling stellen. Darüber hinaus spielte die in den Unterarbeitskreisen vorhandene Expertise der Teilnehmenden eine Rolle beim finalen Zuschnitt der Themen.
Die Ergebnisse aus den Unterarbeitskreisen bilden den inhaltlichen Kern des vollzogenen Dialogprozesses und werden in Steckbriefen beschrieben. So liegen für den Arbeitskreis Metalle detaillierte Steckbriefe für die Stoffströme Aluminium, Eisen und Stahl, Kupfer sowie Technologiemetalle vor.
Der Arbeitskreis Industrieminerale umfasst detaillierte Steckbriefe für die Stoffströme Baurohstoffe, Gips, Keramische Rohstoffe (Feuerfestkeramik) sowie Industrielle Reststoffe und Nebenprodukte.
Insgesamt wurden über die gesamte Projektlaufzeit 94 stoffstromspezifische Handlungsoptionen in den verschiedenen Unterarbeitskreisen erarbeitet, die auf einer systematischen Analyse bestehender Barrieren basieren. Alle Handlungsoptionen für die spezifischen Stoffströme finden sich im jeweiligen Steckbrief. Auf Ebene der beiden Arbeitskreise Metalle und Industrieminerale wurden zudem neun stoffstromübergreifende Handlungsfelder aggregiert, zu denen unter den Teilnehmenden Einigkeit erzielt werden konnte. Weitere Themenbereiche, die einem verbesserten Recycling potenziell zuträglich sind, zu denen jedoch kontroverse Diskussionen unter den Teilnehmenden stattfanden, werden in diesem Bericht transparent dargelegt. Ferner ist zu beachten, dass alle übergreifenden Handlungsfelder einen direkten Recyclingbezug aufweisen. Weiter gefasste wirtschaftspolitische Instrumente, zum Beispiel aus dem Bereich der Klimapolitik, die ebenfalls einen förderlichen Effekt auf ein verstärktes Recycling haben können, wie eine CO2-Bepreisung oder ein Emissionshandel, sind daher nicht vertiefend in der Dialogarbeit aufgegriffen worden. Nachfolgend sind die übergreifenden Handlungsfelder der beiden Arbeitskreise kurz zusammengefasst, wobei die Relevanz der genannten Themen zwischen den Unterarbeitskreisen zum Teil erheblich variiert.
Die ausführlichen Steckbriefe der acht stoffstromspezifischen Unterarbeitskreise, die in dieser Kurzfassung nur umrissen werden, umfassen weitere Handlungsoptionen und betten diese jeweils in die Ausgangslage des Status quo und die daraus resultierenden Barrieren für das Recycling ein. Des Weiteren umfassen die separat zur Verfügung gestellten Steckbriefe eine differenzierte Beurteilung der „Machbarkeit“ sowie möglicher Zielkonflikte in der Umsetzung der jeweiligen Handlungsoptionen. Gerade diese einbettende Betrachtung der vorgeschlagenen Handlungsoptionen stellt einen zentralen Mehrwert der Dialogarbeit dar, da den Lesenden hierdurch ein umfassenderes Verständnis der Vor- und gegebenenfalls auch Nachteile ermöglicht werden soll.
Keywords: Rohstoffe; Recylcing; Versorgungssicherheit; Industrie; Arbeitskreis Metalle; Metalle
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Other report
Berlin: DERA, 2023
30 Seiten
DOI: 10.25928/k89y-b555
Permalink: https://www.hzdr.de/publications/Publ-37959
Publ.-Id: 37959
Terahertz Néel spin-orbit torques drive nonlinear magnon dynamics in antiferromagnetic Mn2Au
Behovits, Y.; Chekhov, A. L.; Bodnar, S. Y.; Gueckstock, O.; Reimers, S.; Lytvynenko, Y.; Skourski, Y.; Wolf, M.; Seifert, T. S.; Gomonay, O.; Kläui, M.; Jourdan, M.; Kampfrath, T.
Antiferromagnets have large potential for ultrafast coherent switching of magnetic order with minimum heat dissipation. In materials such as Mn2Au and CuMnAs, electric rather than magnetic fields may control antiferromagnetic order by Néel spin-orbit torques (NSOTs). However, these torques have not yet been observed on ultrafast time scales. Here, we excite Mn2Au thin films with phase-locked single-cycle terahertz electromagnetic pulses and monitor the spin response with femtosecond magneto-optic probes.We observe signals whose symmetry, dynamics, terahertz-field scaling and dependence on sample structure are fully consistent with a uniform inplane antiferromagnetic magnon driven by field-like terahertz NSOTs with a torkance of (150 ± 50) cm2 A−1 s−1. At incident terahertz electric fields above 500 kV cm−1, we find pronounced nonlinear dynamics with massive Néelvector deflections by asmuch as 30°. Our data are in excellent agreement with a micromagnetic model. It indicates that fully coherent Néel-vector switching by 90° within 1 ps is within close reach.
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Nature Communications 14(2023), 6038
Online First (2023) DOI: 10.1038/s41467-023-41569-z
arXiv: https://arxiv.org/abs/2305.03368
Cited 2 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-37957
Publ.-Id: 37957
Data publication: Minor Actinides Can Replace Essential Lanthanides in Bacterial Life
Singer, H.; Steudtner, R.; Klein, A. S.; Rulofs, C.; Zeymer, C.; Drobot, B.; Pol, A.; Martinez-Gomez, C.; Daumann, L. J.
Rohdaten aus denen Ergebnisse und Grafiken erstellt wurden um die benötigten Erkenntnisse für diese Publikation zu generieren
Keywords: Actinides; Lanthanides; Lanthanide-dependent bacteria; Methanol dehydrogenases; Lanthanide-binding proteins; Methane
Related publications
- DOI: 10.1002/anie.202303669 references this (Id 37956) publication
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Minor Actinides Can Replace Essential Lanthanides in Bacterial Life
ROBIS: 34897 has used this (Id 37956) publication of HZDR-primary research data
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Reseach data in the HZDR data repository RODARE
Publication date: 2023-12-04 Open access
DOI: 10.14278/rodare.2590
Versions: 10.14278/rodare.2591
License: CC-BY-4.0
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Permalink: https://www.hzdr.de/publications/Publ-37956
Publ.-Id: 37956
Wire-mesh sensor data for vertical upward gas-liquid flow
This data set contains the processed data of the wire-mesh sensor, obtained in a flow loop with inner diameter of 50 mm with a vertical section of 3 m length. The dimension of the sensor is 16x16 wires and a lateral wire distance of 3.125 mm. Each file contains data of 60 s measurement time with 10 kHz samling frequency.
The set up was operated with pressurized air and deionized water. The experimental matrix contains meausrements at different superficial velocities of the gas and the liquid. Thus different flow pattern are observed. For injection of the gas two different types have been used. In the first set of experiments (files 1- 61, *injection1*) the gas was injected with a small tube with inner diameter of 9 mm. In the second set of experiments (files 101 - 151, *injection2*) the gas was injected with a small pipe of 25 mm inner diameter.
An overview of the experimental conditions for the two sets of experiments are summarized in the excel file. The corresponding *.zip files contain the processed data. These are void files, which contain the gas holdup in each crossing point and for all time steps of the measurement stack. Additionally the time averaged cross sectional gas holdup distribution (*.epsxy), the time averaged radial gas holdup (*.epsrad_20) and the cross sectional average gas holdup at each time step (*.epst) is provided,
Keywords: two-phase flow; wire-mesh sensor
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Reseach data in the HZDR data repository RODARE
Publication date: 2023-11-28 Restricted access
DOI: 10.14278/rodare.2577
Versions: 10.14278/rodare.2578
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Permalink: https://www.hzdr.de/publications/Publ-37954
Publ.-Id: 37954
Introducing Relative Encounter Rates: a scale-invariant home range measure of animal interaction
Saraiva De Menezes, J. F.; Fleming, C. H.; Martinez Garcia, R.; Belant, J. L.; Medici, E. P.; Morato, R. G.; Calabrese, J.
Animal encounters are key components of population dynamics, community dynamics, and
evolutionary processes. Consequently, measuring encounter rates (i.e. encounters per time) can be
insightful. Encounter rates can be measured from animal tracking data, using metrics that can be split
into two groups. The first group consists of trajectory-based metrics, i.e. measures based on serial
records of animal locations. This first group includes PROX, the number of observed per number of
samples. The second group, in contrast, consists of metrics based on home range overlap, including
the Bhattacharyya coefficient (BC). In this study, we argue both types of metrics are limited.
Trajectory-based metrics are direct measures of encounter rates but have statistical estimation
issues due to their dependency on the frequency of location sampling. Meanwhile, home-rangebased metrics are statistically sound but are not proportional to encounter rates. To overcome both
challenges, we proposed a new metric, Relative Encounter Rate (RER). RER increases linearly with the
number of encounters and does not depend on the frequency of sampling (i.e. it is scale-invariant). In
an individual-based simulation, we measured how RER, BC, and PROX relative error under different
sample sizes and sampling frequencies. Further, we compared these metrics in three empirical case
studies. We tested Jaguars for polygyny, deforestation effects on tapir connectivity, and an extension
of the dearest enemy hypothesis with brown bears. We also compared partner hierarchy according
to BC and RER in Jaguar mating clusters. In the simulation study, we found PROX overestimates the
encounter rate when data has a low sampling frequency. The simulation also indicates BC
overestimated encounters. Furthermore, PROX led to false positives in the Tapir and Bear case
studies. In addition, PROX was incapable of detecting many individual relationships in the jaguar
polygyny study. RER does not depend on sampling frequency (contrary to PROX) or sample size
(contrary to BC). We discuss further hypotheses to test with RER and argue RER can enable ecologists
to analyze encounters with a level of detail adequate to their importance, leading to a better
understanding of how individual behaviors influence population and community dynamics.
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Poster
GRC Movement Ecology Conference, 28.05.-02.06.2023, Renaissance Tuscany Il Ciocco, Italy
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Permalink: https://www.hzdr.de/publications/Publ-37953
Publ.-Id: 37953
Knowledge and technology transfer in and beyond mineral exploration
Kesselring, M.; Kirsch, M.; Wagner, F.; Gloaguen, R.
In natural sciences, mineral exploration has a high network centrality. For industries with high technological- and knowledge proximity, transfer effects are an important function for innovation. Despite the high level of proximity between mineral exploration and other natural sciences, scholars hardly examine transfers from and to mineral exploration. This paper analyzes obstacles and mechanisms of transfer effects in and from mineral exploration and finds answers on how to institutionalize knowledge and technology transfer (KTT). The study employs a qualitative research design. The underlying database consists of 16 expert interviews, from the fields of natural science. The results show that KTT between areas as diverse as mineral exploration, healthcare, and arts are possible. A lack of interdisciplinary exchange and rigid scientific structures is the main inhibitor of KTT. Before this study, evidence for KTT from and to smaller industries is mostly anecdotal. The study is among the few, which investigates KTT concerning functional transfer opportunities.
Keywords: Knowledge transfer; Technology transfer; Mineral exploration; Natural sciences
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Journal of Innovation and Entrepreneurship 12(2023), 74
DOI: 10.1186/s13731-023-00316-w
Permalink: https://www.hzdr.de/publications/Publ-37952
Publ.-Id: 37952
Effect of carbon content on electronic structure of uranium carbides
Butorin, S. M.; Bauters, S.; Amidani, L.; Beck, A.; Rossberg, A.; Weiss, S.; Vitova, T.; Kvashnina, K.; Tougait, O.
The electronic structure of UC (x = 0.9, 1.0, 1.1, 2.0) was studied by means of x-ray absorption spectroscopy (XAS) at the C K edge and measurements in the high energy resolution fluorescence detection (HERFD) mode at the U and edges. The full-relativistic density functional theory calculations taking into account the Coulomb interaction U and spin-orbit coupling (DFT+U+SOC) were also performed for UC and UC. While the U HERFD-XAS spectra of the studied samples reveal little difference, the U HERFD-XAS spectra show certain sensitivity to the varying carbon content in uranium carbides. The observed gradual changes in the U HERFD spectra suggest an increase in the C 2p-U 5f charge transfer, which is supported by the orbital population analysis in the DFT+U+SOC calculations, indicating an increase in the U 5f occupancy in UC as compared to that in UC. On the other hand, the density of states at the Fermi level were found to be significantly lower in UC, thus affecting the thermodynamic properties. Both the x-ray spectroscopic data (in particular, the C K XAS measurements) and results of the DFT+U+SOC calculations indicate the importance of taking into account U and SOC for the description of the electronic structure of actinide carbides.
Related publications
- DOI: 10.1107/S1600577520014265 is cited by this (Id 37950) publication
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Scientific Reports 13(2023), 20434
DOI: 10.1038/s41598-023-47579-7
Permalink: https://www.hzdr.de/publications/Publ-37950
Publ.-Id: 37950
Influence of the cement additive PBTC on aquatic uranium(VI) speciation and retention on cementitious material
Wollenberg, A.; Acker, M.; Kretzschmar, J.; Schmeide, K.; Tsushima, S.; Chiorescu, I.; Krüger, S.
The ingress of water into an underground nuclear repository, described as a worst-case scenario, can lead to the degradation of cement-based engineered barriers and thus to the release of organic cement additives that can affect radionuclide immobilisation. The additive 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) is one of the most commonly used long-term retarders in cement, and also used as a corrosion inhibitor in reinforced concrete and steel. PBTC
is an organophosphonate ligand with one phosphonate and three carboxyl groups [1]. These functional groups make PBTC an effective dispersant and strong complexing agent for various metal ions (e.g. Ca2+, Al3+, Fe3+). However, neither the complexation of radionuclides by PBTC nor the influence of PBTC on radionuclide retention in cement phases has been investigated.
Therefore, both the complexation of U(VI) with PBTC in solution (binary system) and the influence of PBTC on the U(VI) retention by cementitious materials (ternary system) were investigated for the first time. The U(VI) complexation studies were performed by different series varying the pH from 2 to 11 and/or the U(VI) to PBTC ratio. The structure-sensitive methods NMR, IR and Raman spectroscopy were used to characterize the complex structure. Complementary DFT calculations were carried out. The U(VI) speciation in presence of PBTC was determined by UV-Vis and TRLFS spectroscopy. In the case of PBTC excess, soluble complex species are formed up to pH >10, which is relevant for cementitious systems due to degradation processes. For the U(VI) retention studies both calcium (aluminate) silicate hydrate (C-(A-)S-H) phases of different compositions, representing different cement degradation stages, as well as hardened cement paste were applied. TRLFS was applied to characterize the U(VI) binding. The PBTC retention was quantified by 1H and 31P solution NMR.
Keywords: uranium; 2-phosphonobutane-1,2,4-tricarboxylic acid; complexation; stability constants; cement; retention; spectroscopy
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Lecture (Conference)
Joint 6th International Workshop on Mechanisms and Modelling of Waste / Cement Interactions, 20.-22.11.2023, Prague, Czech Republic
Permalink: https://www.hzdr.de/publications/Publ-37949
Publ.-Id: 37949
Structural identification of aquatic U(VI)-PBTC complexes by spectroscopic investigations
Wollenberg, A.; Kretzschmar, J.; Tsushima, S.; Krüger, S.; Acker, M.; Taut, S.; Stumpf, T.
In a nuclear waste repository, cement-based materials are to be used for waste conditioning and as an engineered barrier. The ingress of water into the nuclear waste repository, described as a worst-case scenario, leads to increased aging and degradation of the concrete. These processes are associated with a leaching of diverse organic substances usually added to the cement to realize the desired physicochemical and mechanical properties of the cement-based materials. The impact of the additives is based on their excellent ability to complex metal ions. Consequently, the complexation behavior of such additives towards radionuclides (RN) and thus their impact on RN mobilization and migration into the environment is essential for a comprehensive risk assessment. One of the additives commonly used for long-term retardation of cement hardening is 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC).
PBTC is a polyfunctional ligand possessing three carboxyl groups and one phosphonate group, which have been shown to make PBTC a strong complexing agent for various metal ions (e.g. Ca2+, Zn2+, Al3+, Fe3+) [1,2]. However, to date, there are no studies on PBTC interaction with radionuclides. Therefore,
the complexation of PBTC with U(VI) was investigated for the first time, using different spectroscopic methods over a wide pH range (2 through 11) to identify and characterize possible complex species.
U(VI)-PBTC species with solubility as high as 100 mM were observed throughout the entire pH range studied, especially when PBTC is in excess. This allowed the convenient application of structuresensitive methods such as NMR, IR, and Raman spectroscopies. Furthermore, time-resolved laserinduced
fluorescence spectroscopy (TRLFS) and UV-Vis titration studies provided insight into U(VI)–PBTC system’s speciation.
Keywords: uranium(VI); 2-phosphonobutane-1,2,4-tricarboxylic acid; complexation; stability constants; spectroscopy
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Lecture (Conference)
18th International Conference on the Chemistry and Migration Behaviour of Actinides and Fission Products in the Geosphere - Migration 2023, 24.-29.09.2023, Nantes, France
Permalink: https://www.hzdr.de/publications/Publ-37948
Publ.-Id: 37948
Characterisation of highly soluble U(VI)-PBTC complexes
Wollenberg, A.; Kretzschmar, J.; Schmeide, K.; Acker, M.; Taut, S.; Stumpf, T.
Organophosphonates are used multipurpose in the chemical industry. One of the most commonly used organophosphonates is 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC).[1] The functional groups of PBTC consist of one phosphonate and three carboxylate groups, which make PBTC not only an effective dispersant, but also a very good complexing agent for various metal ions (e.g. Ca2+, Al3+, Fe3+).[2,3] Due to these properties, PBTC is used, for example, as an efficient long-term retarder in cement, as a corrosion inhibitor in reinforced concrete and steel, or as a scale inhibitor in water treatment plants or cooling water circulation systems.[4,5] However, this ubiquitous use can also lead to anthropogenic discharge into the environment, where PBTC can complex heavy metals or even radionuclides. Complexation can increase the solubility of metal ions and thus their bioavailability. As a result, there is an increased risk of toxic metal ions being distributed in the environment and thus also being absorbed into the human food chain.
However, to date there have been no studies on the complexation of PBTC with radionuclides. For this reason, the complexation of PBTC with U(VI) in the pH range from 1 to 11 was investigated for the first time using various spectroscopic methods. The studies were performed by different series varying the pH or the U(VI) to PBTC ratio. For the methods used, U(VI) concentrations in the mM range were employed, which was possible due to the very good water solubility of the U(VI)-PBTC complexes. The structure-sensitive methods NMR, IR and Raman spectroscopy were used to characterise the complex structure. Supporting DFT calculations were carried out. The stability constants of the complex species were determined by UV-Vis spectroscopy. By applying the different spectroscopic methods, it was possible to determine chelation of U(VI) by the phosphonate group and one of the carboxyl groups. Furthermore, by means of factor analysis, the distribution of complex species as well as the complexation constants could be determined for the first time. Therefore, the results of this study make it possible to evaluate the risk of PBTC entering the environment in relation to the radionuclide uranium.
Keywords: uranium(VI); 2-phosphonobutane-1,2,4-tricarboxylic acid; complexation; stability constants; spectroscopy
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Lecture (Conference)
5th International Caparica Conference on Pollutant Toxic Ions and Molecules (PTIM) 2023, 06.-09.11.2023, Caparica, Portugal
Permalink: https://www.hzdr.de/publications/Publ-37947
Publ.-Id: 37947
Magnetic structure and phase diagram of the Heisenberg-Ising spin chain antiferromagnetic PbCo2V2O8
Puniak, K.; Aguilar-Maldonado, C.; Feyerherm, R.; Prokes, K.; Islam, A. T. M. N.; Skourski, Y.; Keller, L.; Lake, B.
The effective spin-1/2 antiferromagnetic Heisenberg-Ising chain materials, ACo2V2O8, A = Sr, Ba, are a rich source of exotic fundamental phenomena and have been investigated for their model magnetic properties both in zero and nonzero magnetic fields. Here we investigate a new member of the family, namely, PbCo2V2O8. We synthesize powder and single-crystal samples of PbCo2V2O8 and determine its magnetic structure using neutron diffraction. Furthermore, the magnetic field/temperature phase diagrams for a magnetic field applied along the c, a, and [110] crystallographic directions in the tetragonal unit cell are determined via magnetization and heat capacity measurements. A complex series of phases and quantum phase transitions are discovered that strongly depend on both the magnitude and direction of the field. Our results show that PbCo2V2O is an effective spin-1/2 antiferromagnetic Heisenberg-Ising chain with properties that are, in general, comparable to those of SrCo2V2O8 and BaCo2V2O8. One interesting departure from the results of these related compounds is, however, the discovery of a new field-induced phase for the field direction H ӏӏ [110].
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Physical Review B 108(2023), 144432
DOI: 10.1103/PhysRevB.108.144432
arXiv: https://arxiv.org/abs/2309.16419
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Permalink: https://www.hzdr.de/publications/Publ-37943
Publ.-Id: 37943
300 mm CMOS-compatible superconducting HfN and ZrN thin films for quantum applications
Potjan, R.; Wislicenus, M.; Ostien, O.; Hoffmann, R.; Lederer, M.; Reck, A.; Emara, J.; Roy, L.; Lilienthal-Uhlig, B.; Wosnitza, J.
The rising interest in increased manufacturing maturity of quantum processing units is pushing the development of alternative superconducting materials for semiconductor fab process technology. However, these are often facing CMOS process incompatibility. In contrast to common CMOS materials, such as Al, TiN, and TaN, reports on the superconductivity of other suitable transition-metal nitrides are scarce, despite potential superiority. Here, we demonstrate fully CMOS-compatible fabrication of HfN and ZrN thin films on state-of-the-art 300mm semiconductor process equipment, utilizing reactive DC magnetron sputtering on silicon wafers. Measurement of mechanical stress and surface roughness of the thin films demonstrates process compatibility. We investigated the materials phase and stoichiometry by structural analysis. The HfN and ZrN samples exhibit superconducting phase transitions with critical temperatures up to 5.84 and 7.32 K, critical fields of 1.73 and 6.40 T, and coherence lengths of 14 and 7 nm, respectively. A decrease in the critical temperature with decreasing film thickness indicates mesoscopic behavior due to geometric and grain-size limitations. The results promise a scalable application of HfN and ZrN in quantum computing and related fields.
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Applied Physics Letters 123(2023), 172602
Online First (2023) DOI: 10.1063/5.0176060
Permalink: https://www.hzdr.de/publications/Publ-37942
Publ.-Id: 37942
Local-symmetry-sensitive elastic softening in the Kramers doublet system Y1−xNdxCo2Zn20
Ishii, I.; Umeno, T.; Yamamoto, R.; Onimaru, T.; Suzuki, T.; Araki, K.; Miyata, A.; Zherlitsyn, S.; Wosnitza, J.
We investigated the elastic properties of Y1−xNdxCo2Zn20 with localized Nd f electrons and ground-state Kramers doublet. All longitudinal and transverse moduli of NdCo2Zn20 (x = 1) show an elastic softening below 50 K accompanied by a minimum around 2.5 K. The softening, which is robust to magnetic fields up to 8 T, is not observed for samples with Nd concentrations of x = 0.19, 0.05, and 0. In localized f electron systems, elastic softening from high temperatures is often understood by crystal electric field effects; however, this cannot explain the behavior in NdCo2Zn20. Our experimental and calculated results reveal that the softening neither is caused by a phonon contribution, a Nd3+ single-site effect, nor a magnetic interaction. We conclude that the softening is due to a local-symmetry-sensitive electronic state in NdCo2Zn20.
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Physical Review B 108(2023), 205127
DOI: 10.1103/PhysRevB.108.205127
Permalink: https://www.hzdr.de/publications/Publ-37941
Publ.-Id: 37941
Giant irreversibility of the inverse magnetocaloric effect in the Ni47Mn40Sn12.5Cu0.5 Heusler alloy
Kamantsev, A. P.; Koshkidko, Y. S.; Bykov, E.; Gottschall, T.; Gamzatov, A. G.; Aliev, A. M.; Varzaneh, A. G.; Kameli, P.
Direct studies of the adiabatic temperature change (ΔTad) in the Ni47Mn40Sn12.5Cu0.5 Heusler alloy in steady magnetic fields up to 8 T by the extraction method and in pulsed magnetic fields up to 50 T were carried out in this paper. The alloy Ni47Mn40Sn12.5Cu0.5 demonstrates a magnetostructural phase transition (MSPT) of the first order in the 254–283 K temperature range as well as a second order phase transition near the Curie temperature TC = 313 K. An inverse magnetocaloric effect (MCE) was found in the region of the MSPT, and it reaches the maximum value ΔTad = -12 K in 20 T at the initial temperature T0 = 275 K. The irreversible part of the MCE reached ΔTir = -10 K when the field is completely removed. We consider the dynamics of the MCE in the vicinity of the MSPT and discuss the mechanisms that cause the giant irreversibility of the MCE as well as the possibilities of its application in hybrid cooling systems.
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Applied Physics Letters 123(2023), 202405
DOI: 10.1063/5.0176772
Permalink: https://www.hzdr.de/publications/Publ-37940
Publ.-Id: 37940
Foundational Competencies and Responsibilities of a Research Software Engineer
Goth, F.; Alves, R.; Braun, M.; Jael Castro, L.; Chourdakis, G.; Christ, S.; Cohen, J.; Erxleben, F.; Grad, J.-N.; Hagdorn, M.; Hodges, T.; Juckeland, G.; Kempf, D.; Lamprecht, A.-L.; Linxweiler, J.; Schwarzmeier, M.; Seibold, H.; Philipp Thiele, J.; von Waldow, H.; Wittke, S.
The term Research Software Engineer, or RSE, emerged a little over 10 years ago as a way to represent
individuals working in the research community but focusing on software development. The term has been widely
adopted and there are a number of high-level definitions of what an RSE is. However, the roles of RSEs vary
depending on the institutional context they work in. At one end of the spectrum, RSE roles may look similar to
a traditional research role. At the other extreme, they resemble that of a software engineer in industry. Most
RSE roles inhabit the space between these two extremes. Therefore, providing a straightforward, comprehensive
definition of what an RSE does and what experience, skills and competencies are required to become one is
challenging. In this community paper we define the broad notion of what an RSE is, explore the different types
of work they undertake, and define a list of fundamental competencies as well as values that define the general
profile of an RSE. On this basis, we elaborate on the progression of these skills along different dimensions, looking
at specific types of RSE roles, proposing recommendations for organisations, and giving examples of future
specialisations. An appendix details how existing curricula fit into this framework.
Keywords: research software engineering; curriculum design; training; learning; competencies; certification
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Contribution to WWW
https://arxiv.org/pdf/2311.11457.pdf
DOI: 10.48550/arXiv.2311.11457
arXiv: 2311.11457
Permalink: https://www.hzdr.de/publications/Publ-37938
Publ.-Id: 37938
Helmholtz Metadata Collaboration - Facilitating FAIR metadata in Helmholtz
Schaller, T.; Günter, G.; Kubin, M.; Özkan, Ö.; Rau, F.; Steinmeier, L.
Data are an essential part of every scientific endeavour. An efficient and future oriented research data management is therefore essential in order to ensure long-term availability of the generated data. This in turn ensures the reproducibility of scientific results. In order to facilitate FAIR data management within the Helmholtz community the incubator platform “Helmholtz Metadata Collaboration (HMC)” was established.
HMC develops and provides services, tools and trainings to support and improve FAIR (meta)data management in the Helmholtz Association and aligns these approaches with national and international approaches and initiatives (e.g. RDA, EOSC, NFDI) to ensure compatibility with international research communities.
To achieve this goal, HMC builds its work along three strategic areas: (1) Assessing and monitoring the state of FAIR data across Helmholtz, (2) Facilitating the connectivity of Helmholtz research data, and (3) Transforming (meta)data recommendations into implementations. At the centres, HMC supports research communities and data professionals with six research-field specific hubs: At HZDR HMC is represented locally by a unit dedicated to research field Energy and remotely by a unit for research field Matter. In our poster we will illustrate how research and data professional communities at HZDR can benefit from HMC's services, tools and trainings.
Keywords: Helmholtz-Zentrum Dresden-Rossendorf; HZDR data management day; metadata management; Helmholtz Metadata Collaboration
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Poster
HZDR Data Management Day, 21.11.2023, Dresden, Dresden
Permalink: https://www.hzdr.de/publications/Publ-37937
Publ.-Id: 37937
Influence of selected organics on the retention of uranium(VI) by calcium-(aluminate-)silicate-hydrate phases
Schmeide, K.; Kretzschmar, J.; Huittinen, N. M.
Most underground nuclear waste disposal concepts envisage the extensive use of cementitious materials in the geo-engineered barrier as a buffer and borehole sealing material and to ensure the mechanical stability of disposal systems. In order to assess the radionuclide (RN) retention potential of these barrier materials, it is necessary to study the impact of various repository relevant conditions that will evolve over time, such as changed pH values, increased ionic strength, elevated temperatures, or the release of organic components. The U(VI) retention by calcium (aluminate) silicate hydrate (C-(A-)S-H) phases, forming owing to Al-rich additives in cement formulations, was studied for samples with C/S molar ratios of 0.8, 1.2, and 1.6, representing different alteration stages of concrete, and with increasing A/S molar ratios of 0, 0.06, and 0.18 in each series, with special focus on the presence of organics. The latter thereby comprise gluconate (GLU), 2-phosphonobutane-1,2,4,-tricarboxylate (PBTC), and a mixture of cellulose degradation products (CDP) obtained from dry radiolysis (dose rate 0.6 kGy/h, absorbed dose ~ 1.37 MGy) followed by hydrolysis in artificial cement water (pH > 13, anoxic conditions) provided by project partners within the CORI framework. Complementary analytical techniques were applied to address the different specific aspects of the cement / organics / RN ternary systems. 27Al and 29Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy and powder X-ray diffraction (XRD) were applied to determine the bulk structure and composition of the synthesized C-(A-)S-H phases. 13C-, and in case of PBTC also 31P-, MAS NMR measurements aimed at localization and speciation of the organic components involved [1]. 1H and 31P solution NMR of the aqueous phase allowed for quantification of the organics’ fraction removed from solution and hence associated with the solid phase. Retained U(VI) species were identified by time-resolved laser-induced luminescence spectroscopy (TRLFS). Zeta-potential measurements were conducted to study the organics’ influence on the surface charge and, upon changing the order of mixing the individual components of the ternary systems (e.g., C-(A-)S-H phases synthesized in absence or presence of U(VI) and/or organics), along with results from spectroscopies, to derive mechanistic understanding of retention processes as well as surface complex models.
Keywords: uranium; C-S-H; C-A-S-H; hydrothermal synthesis; luminescence; spectroscopy
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Lecture (Conference)
Joint 6th International Workshop on Mechanisms and Modelling of Waste / Cement Interactions, 20.-22.11.2023, Prague, Czech Republic
Permalink: https://www.hzdr.de/publications/Publ-37936
Publ.-Id: 37936
NiGe formation on thin Ge films by flash lamp annealing: electrical properties
Begeza, V.; Rebohle, L.; Stöcker, H.; Mehner, E.; Hübner, R.; Zhou, S.
Flash lamp annealing (FLA) is an ultra-short annealing method which excellently meets the requirements of thin film processing and has already been used in microelectronics. Due to the relatively high hole mobility, thin Ge layers are highly interesting as a transistor channel material or generally as a functional layer both in CMOS technology and in the field of low-cost electronics. One possibility to realize ohmic contacts with low contact resistance is the use of metal germanides, especially the stoichiometric NiGe phase.
In this work, NiGe contacts on thin Ge films were fabricated by magnetron sputtering followed by FLA. The evolution of microstructure with increasing thermal budget was traced by transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The electrical measurements focus on the determination of contact resistance by the circular transfer length method (cTLM). The contacts were fabricated by two different approaches, and the influence of different process steps on layer morphology and the uncertainty of the measurement was studied.
Keywords: germanium; nickel germanide; thin films; sputtering; flash lamp annealing; circular transfer length
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 37931) publication
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Lecture (Conference)
E-MRS SPRING MEETING 2023, 29.05.-02.06.2023, Strasbourg, Frankreich
Permalink: https://www.hzdr.de/publications/Publ-37931
Publ.-Id: 37931
NiGe formation on thin Ge films by flash lamp annealing
Begeza, V.; Rebohle, L.; Stöcker, H.; Mehner, E.; Hübner, R.; Zhou, S.
In this work, NiGe contacts on thin Ge films were fabricated by magnetron sputtering followed by flash lamp annealing (FLA). The evolution of microstructure with increasing thermal budget was traced by transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. The film sheet resistance, the free charge carrier mobility and concentration, and the contact resistance were measured by the four-point-probe method, by Hall effect measurements, and by the circular transfer length method, respectively. Based on this data, the formation process of NiGe contacts during FLA is described, which passes through a stage of Ni-rich phases with high electrical resistivity, before the final stoichiometric NiGe phase is formed.
Keywords: germanium; nickel germanide; thin films; sputtering; flash lamp annealing; circular transfer length
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 37930) publication
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Lecture (Conference)
Nutzertreffen Heissprozesse und Ionenimplantation, 10.-11.05.2023, Erlangen, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-37930
Publ.-Id: 37930
Data publication: Cadmium sorption on alumina nanoparticles, and mixtures of alumina and smectite: An experimental and modelling study
Mayordomo, N.; Missana, T.; Alonso, U.
Data is shown in origin, the thermodynamic database of Cd is adapted for Chess V2 software
Keywords: Cd; sorption model; retention; immobilization; heavy metals; Al2O3
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Reseach data in the HZDR data repository RODARE
Publication date: 2023-11-24 Open access
DOI: 10.14278/rodare.2569
Versions: 10.14278/rodare.2570
License: CC-BY-4.0
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Permalink: https://www.hzdr.de/publications/Publ-37929
Publ.-Id: 37929
Learning Crop-Type Mapping From Regional Label Proportions in Large-Scale SAR and Optical Imagery
La Rosa, L.; Oliveira, D.; Ghamisi, P.
The application of deep learning (DL) algorithms to Earth observation (EO) in recent years has enabled substantial progress in fields that rely on remotely sensed data. However, given the data scale in EO, creating large datasets with pixel-level annotations by experts is expensive and highly time-consuming. In this context, priors are seen as an attractive way to alleviate the burden of manual labeling when training DL methods for EO. For some applications, those priors are readily available. Motivated by the great success of contrastive-learning methods for self-supervised feature representation learning in many computer-vision tasks, this study proposes an online deep clustering method using crop label proportions as priors to learn a sample-level classifier based on government crop-proportion data for a whole agricultural region. We evaluate the method using two large datasets from two different agricultural regions in Brazil. Extensive experiments demonstrate that the method is robust to different data types [synthetic-aperture radar (SAR) and optical images], reporting higher accuracy values considering the major crop types in the target regions. Thus, it can alleviate the burden of large-scale image annotation in EO applications.
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IEEE Transactions on Geoscience and Remote Sensing 61(2023), 4409615
DOI: 10.1109/TGRS.2023.3321156
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- Open Access Version from arxiv.org
- Secondary publication expected from 02.10.2024
Permalink: https://www.hzdr.de/publications/Publ-37928
Publ.-Id: 37928
Leveraging involution and convolution in an explainable building damage detection framework
Teymoor Seydi, S.; Hasanlou, M.; Chanussot, J.; Ghamisi, P.
Timely and accurate building damage mapping is essential for supporting disaster response activities. While RS satellite imagery can provide the basis for building damage map generation, detection of building damages by traditional methods is generally challenging. The traditional building damage mapping approaches focus on damage mapping based on bi-temporal pre/post-earthquake dataset extraction information from bi-temporal images, which is difficult. Furthermore, these methods require manual feature engineering for supervised learning models. To tackle the abovementioned limitation of the traditional damage detection frameworks, this research proposes a novel building damage map generation approach based only on post-event RS satellite imagery and advanced deep feature extractor layers. The proposed DL based framework is applied in an end-to-end manner without additional processing. This method can be conducted in five main steps: (1) pre-processing, (2) model training and optimization of model parameters, (3) damage mapping generation, (4) accuracy assessment, and (5) visual explanations of the proposed method’s predictions. The performance of the proposed method is evaluated by two real-world RS datasets that include Haiti-earthquake and Bata-explosion. Results of damage mapping show that the proposed method is highly efficient, yielding an OA of more than 84%, which is superior to other advanced DL-based damage detection methods.
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European Journal of Remote Sensing (2023), 2252166
Online First (2023) DOI: 10.1080/22797254.2023.2252166
Permalink: https://www.hzdr.de/publications/Publ-37927
Publ.-Id: 37927
Earthquake spatial probability and hazard estimation using various explainable AI (XAI) models at the Arabian peninsula
Ratiranjan, J.; Abdallah, S.; Rami, A.-R.; Biswajeet, P.; Mohamed, B. A. G.; Mohamad, A. K.; Omid, G.; Ghamisi, P.
Earthquakes are the most destructive natural hazards because of their adversely severe impacts on urban areas. Earthquakes affect people's lives and properties, thus captivating the extensive attention of seismologists. Carrying out probability and hazard assessment for the prevention, and reduction of mega-events and recovery will be of great significance in affected areas. Given that limited studies have attempted to estimate earthquake Spatial Probability Assessment (SPA) in the Arabian Peninsula, this study aims to evaluate the SPA and Earthquake Hazard Assessment (EHA). This study implements and evaluates various machine learning and explainable-AI (XAI) techniques for the estimation of SPA and EHA in the Arabian Peninsula, explores the contribution and highlights the importance of different factors in the development of AI-based models. A total of twelve factors ranging from seismological to geophysical factors were evaluated. Two machine learning models namely Light Gradient Boosting Machine (LightGBM) and deep Recurrent Neural Networks (RNN) along with three XAI approaches (i.e, Smart predictor, Smart Explainer and Local Interpretable Model-Agnostic Explanation (LIME) model) were investigated. Results of the comparative earthquake SPA estimation demonstrated that the accuracy of 89% and 87% were achieved by LightGBM and RNN models. Moreover, the results of the XAI models show that the Smart Predictor provides better spatial outputs than the other evaluated XAI models. The stable factors identified by Smart Predictor were magnitude variation and earthquake frequency whereas the important factors were magnitude variation, earthquake frequency, depth variation, and seismic gap. Collectively, results of SPA show that, the Gulf of Aden, Red Sea, Iran, and Turkey are falling under a very-high SPA index (0.991–1). Correspondingly, Gulf areas, coastal areas of Saudi Arabia, and areas in the Zagros fault and Anatolian fault zone fall under a very-high hazard zone. This research could support planners, and decision-makers for emergency planning, infrastructure development, and reconstruction projects.
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Remote Sensing Applications: Society and Environment 31(2023), 101004
DOI: 10.1016/j.rsase.2023.101004
Cited 1 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-37914
Publ.-Id: 37914
Demographic effects of aggregation in the presence of a component Allee effect
Jorge, D. C. P.; Martinez Garcia, R.
Intraspecific interactions are key drivers of population dynamics because they establish relations between individual fitness and population density. The component Allee effect is defined as a positive correlation between any fitness component of a focal organism and population density, and it can lead to positive density dependence in the population per capita growth rate. The spatial population structure is key to determining whether and to which extent a component Allee effect will manifest at the demographic level because it determines how individuals interact with one another. However, existing spatial models to study the Allee effect impose a fixed spatial structure, which limits our understanding of how a component Allee effect and the spatial dynamics jointly determine the existence of demographic Allee effects. To fill this gap, we introduce a spatially-explicit theoretical framework where spatial structure and population dynamics are emergent properties of the individual-level demographic and movement rates. Depending on the intensity of the individual-level processes, the population exhibits a variety of spatial patterns, including evenly spaced aggregates of organisms, that determine the demographic-level by-products of an existing individual-level component Allee effect. We find that aggregation increases population abundance and allows populations to survive in harsher environments and at lower global population densities when compared with uniformly distributed organisms. Moreover, aggregation can prevent the component Allee effect from manifesting at the population level or restrict it to the level of each independent group. These results provide a mechanistic understanding of how component Allee effects might operate for different spatial population structures and show at the population level. Because populations subjected to demographic Allee effects exhibit highly nonlinear dynamics, especially at low abundances, our results contribute to a better understanding of population dynamics in the presence of Allee effects and can potentially inform population management strategies.
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Contribution to WWW
https://arxiv.org/pdf/2305.13414.pdf
DOI: 10.48550/arXiv.2305.13414
arXiv: 2305.13414
Permalink: https://www.hzdr.de/publications/Publ-37907
Publ.-Id: 37907
Development Of A Novel ACE2 Decoy For Both SARS-CoV-2 Variant Neutralization And Infected Cell Elimination Via Unmodified Or CAR Modified Immune Cells
Drewitz, L.; Kegler, A.; Arndt, C.; Daglar, C.; Rodrigues Loureiro, L. R.; Mitwasi, N.; Neuber, C.; González Soto, K. E.; Bartsch, T.; Baraban, L.; Ziehr, H.; Heine, M.; Nieter, A.; Moreira-Soto, A.; Kühne, A.; Drexler, J. F.; Seliger, B.; Laube, M.; Máthé, D.; Pályi, B.; Hajdrik, P.; Forgách, L.; Kis, Z.; Sziget, K.; Bergmann, R.; Feldmann, A.; Bachmann, M.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a pandemic with millions of infections and deaths worldwide and devastating impact on global economy. Up to now, vaccines and monoclonal antibody (mAb) therapies lack to provide a long-lasting protection against rapidly evolving new emerging SARS-CoV-2 variants. Thus, novel therapeutic options are pressingly needed especially for immunocompromised patients and/or patients with high risk for developing a severe coronavirus disease 2019 (COVID-19).
In that regard, we developed a novel immunotherapeutic drug based on the SARS-CoV-2 entry receptor angiotensin-converting enzyme 2 (ACE2). This ACE2 decoy potently binds to the SARS-CoV-2 receptor binding domain (RBD), neutralizes SARS-CoV-2 as well as the Delta and Omicron variant and protects hamsters from a SARS-CoV-2 infection. To additionally use this ACE2 decoy for elimination of virus infected cells, we equipped it with an epitope tag. Thus, it can be applied as adapter molecule in the modular platform technologies UniMAB and UniCAR, which already demonstrated great success in the setting of malignant diseases. As adapter molecule the ACE2 decoy is able to efficiently recruit either universal chimeric antigen receptor (UniCAR) modified T cells or, in combination with an anti-peptide epitope-anti-CD3 bispecific Ab of the UniMAB system, unmodified T cells to efficiently kill SARS-CoV-2 RBD expressing human cells.
Taken together, the ACE2 decoy represents a very promising immunotherapeutic drug for both SARS-CoV-2 variant neutralization and infected cell killing via the UniMAB and UniCAR system and might, therefore, clearly improve the treatment of COVID-19 patients.
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Abstract in refereed journal
Human Gene Therapy 34(2023), 92
Online First (2023) DOI: 10.1089/hum.2023.29252.abstracts
Permalink: https://www.hzdr.de/publications/Publ-37905
Publ.-Id: 37905
openPMD – the Open Standard for Particle-Mesh Data
Huebl, A.; Wan, L.; Lehe, R.; Podhorszki, N.; Gu, J.; Thévenet, M.; Schnetter, E.; Pöschel, F.; Bussmann, M.
The Open Standard for Particle-Mesh Data (openPMD) is a F.A.I.R. metadata standard for tabular (particle/dataframe) and structured mesh data in science and engineering.
We show the basic components of openPMD, its extensions to specific domains, applications from laser-plasma physics, particle accelerators, material physics to imaging and the ability to bridge multiple heterogeneous scientific models with a commonly-understood markup.
The openPMD-api builds upon established portable I/O formats such as HDF5 and ADIOS2, enabling workflows that scale from single-user computers up to Exascale simulations, in-transit data processing, 3D visualization, GPU-accelerated data analytics and AI/ML. openPMD links into the existing ecosystems of its scalable I/O backends and extends them with tooling that understands the openPMD data markup.
An overview over the openPMD ecosystem and community is shown.
Attention is given to recent developments in openPMD that interplay with HDF5, including mesh refinement and the Helmholtz Metadata Collaboration's HELPMI project which aims for an easier integration of openPMD with other HDF5-based standards, this way bringing openPMD closer to experiment workflows.
References:
[1] Axel Huebl, Remi Lehe, Jean-Luc Vay, David P. Grote, Ivo F. Sbalzarini, Stephan Kuschel, David Sagan, Christopher Mayes, Frederic Perez, Fabian Koller, and Michael Bussmann. “openPMD: A meta data standard for particle and mesh based data,” DOI:10.5281/zenodo.591699 (2015)
[2] Homepage: https://www.openPMD.org
[3] GitHub Organization: https://github.com/openPMD
[4] Projects using openPMD: https://github.com/openPMD/openPMD-projects
[4] Reference API implementation: Axel Huebl, Franz Poeschel, Fabian Koller, and Junmin Gu. “openPMD-api 0.14.3: C++ & Python API for Scientific I/O with openPMD,” DOI:10.14278/rodare.1234 (2021)
https://openpmd-api.readthedocs.io
[5] Selected earlier presentations on openPMD:
https://zenodo.org/search?page=1&size=20&q=openPMD&type=presentation
[6] Axel Huebl, Rene Widera, Felix Schmitt, Alexander Matthes, Norbert Podhorszki, Jong Youl Choi, Scott Klasky, and Michael Bussmann. “On the Scalability of Data Reduction Techniques in Current and Upcoming HPC Systems from an Application Perspective,” ISC High Performance 2017: High Performance Computing, pp. 15-29, 2017. arXiv:1706.00522, DOI:10.1007/978-3-319-67630-2_2
[7] Franz Poeschel, Juncheng E, William F. Godoy, Norbert Podhorszki, Scott Klasky, Greg Eisenhauer, Philip E. Davis, Lipeng Wan, Ana Gainaru, Junmin Gu, Fabian Koller, Rene Widera, Michael Bussmann, and Axel Huebl. Transitioning from file-based HPC workflows to streaming data pipelines with openPMD and ADIOS2, Part of Driving Scientific and Engineering Discoveries Through the Integration of Experiment, Big Data, and Modeling and Simulation, SMC 2021, Communications in Computer and Information Science (CCIS), vol 1512, 2022. arXiv:2107.06108, DOI:10.1007/978-3-030-96498-6_6
[8] The Helmholtz Metadata Collaboration's ongoing HELPMI project: https://helmholtz-metadaten.de/de/inf-projects/helpmi-helmholtz-laser-plasma-metadata-initiative
Keywords: F.A.I.R.; openPMD; HDF5; ADIOS2; HPC
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Lecture (Conference)
2023 European HDF User Group (HUG) plugins and data compression summit, 19.-21.09.2023, Hamburg, Deutschland -
Invited lecture (Conferences)
9. Annual MT Meeting, 09.-11.10.2023, Karlsruhe, Deutschland -
Poster
9. Annual MT Meeting, 09.-11.10.2023, Karlsruhe, Deutschland -
Poster
DMA ST1 synergy workshop, 08.-10.11.2023, Hamburg, Deutschland
Downloads
Permalink: https://www.hzdr.de/publications/Publ-37902
Publ.-Id: 37902
Non-coaxial deformation of foreland basement involved in a fold-and-thrust belt: a strain partitioning approach to the Eastern Variscan orogen
Mareček, L.; Melichar, R.; Cerny, J.; Schnabl, P.; Hrdličková, K.; Buriánek, D.
The general SW–NE course of the Variscan orogen in Europe is abruptly bent to the N–S course at its eastern margin, where an oblique convergence occurred. The main suture in this part of the Variscan orogenic belt is called the Moldanubian Thrust, characterized by a dominant dextral strike‑slip kinematics and a minor thrust component. The deep level of erosion and the good exposure of this structure allowed us to study the mechanisms of oblique convergence and the incorporation of the foreland basement into the orogenic belt. The combination of small‑scale structures with the anisotropy of magnetic susceptibility studies allowed the recognition of two deformations in the studied rocks: dextral simple shearing and drag folding. Due to oblique convergence, the deformations induced by this mechanism were non‑coaxial; therefore, their contributions can be easily distinguished. Finally, an overturned, almost recumbent large‑scale synformal fold structure in the footwall and an antiformal structure in the hanging wall of the Moldanubian Thrust were formed. These two folds can be interpreted as structures formed by dragging along the Moldanubian Thrust. The previously described sinistral simple shearing in the upper limb of the synform resulted from the original dextral strike‑slip shearing, which was overturned during progressive deformation.
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Scientific Reports 13(2023), 8143 (2023)
DOI: 10.1038/s41598-023-35400-4
Permalink: https://www.hzdr.de/publications/Publ-37901
Publ.-Id: 37901
Data publication: On the anatomy and structural control of a dyke swarm that fed caldera-forming ignimbrite eruptions
Tomek, F.; Olšanská, I.; Trubač, J.; Cerny, J.; Rejšek, J.; Ackerman, L.
The whole-rock major, trace element and isotope geochemical tables, magnetic fabrics source data and details of methods.
Related publications
- DOI: 10.1144/jgs2022-119 references this (Id 37900) publication
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On the anatomy and structural control of a dyke swarm that fed caldera-forming …
ROBIS: 37899 has used this (Id 37900) publication of HZDR-primary research data
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Reseach data in external data repository
Publication year 2023
License: CC-BY
DOI: 10.6084/m9.figshare.c.6715893
Permalink: https://www.hzdr.de/publications/Publ-37900
Publ.-Id: 37900
On the anatomy and structural control of a dyke swarm that fed caldera-forming ignimbrite eruptions
Tomek, F.; Olšanská, I.; Trubač, J.; Cerny, J.; Rejšek, J.; Ackerman, L.
The evolution of eruptive vents related to calderas is not fully understood. We focus on a structural, rock-magnetic, and geochemical investigation of a ∼314 Ma rhyolite dyke swarm associated with the late-orogenic Altenberg–Teplice Caldera, Bohemian Massif, eastern Variscan belt. The whole-rock major element, trace element, and Nd–Pb isotope geochemistry along with the published U-Pb zircon geochronology link the extra-caldera dyke swarm with intra-caldera ignimbrites. The magnetic fabrics determined using the anisotropy of magnetic susceptibility are interpreted to record a continuum from magma ascent, emplacement, and eruption during sinistral shearing. The latter evidences an interplay with regional tectonics associated with the activity of crustal-scale shear zones. The sinistral kinematics and strike of the dyke swarm, the elongation of caldera intrusive units, and the kinematics of major caldera faults are consistent with the dextral Riedel shear system, where the dykes correspond to antithetic Ŕ/X-shears. Such a kinematic configuration implies that the maximum and minimum principal stresses were oriented roughly north-south and east-west, respectively. The relation between the stress field with respect to the caldera elongation and orientation is not typical. We suggest that a pre-existing mutually perpendicular set of cross-cutting structural lineaments largely controlled the magma chamber and caldera formation.
Related publications
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Data publication: On the anatomy and structural control of a dyke swarm that …
ROBIS: 37900 HZDR-primary research data are used by this (Id 37899) publication
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Journal of the Geological Society 180(2023), jgs2022-119
Online First (2023) DOI: 10.1144/jgs2022-119
Permalink: https://www.hzdr.de/publications/Publ-37899
Publ.-Id: 37899
Datengestützte Intralogistik zur Optimierung von Aufbereitungs- & Recyclingprozessen
Nagel, M.; Rau, F.; Pereira, L.
Intralogistik gewinnt bei der Produktionssteuerung für die Organisation und Optimierung von Zulieferung und Warenumschlag stetig an Bedeutung. Darüber hinaus werden durch Intralogistik innerbetriebliche Materialflüsse und Informationsströme gesteuert und – wenn möglich – die Produktionslogistik intelligent gesteuert.
Die Intralogistik von Aufbereitungs- und Recyclingprozesse unterscheidet sich erheblich von der Intralogistik bei Produktionsprozessen. Bei Herstellung von Produkten und Halbzeugen sind Eigenschaften von Ausgangsmaterialien meist chargengenau bekannt. Während bei der Aufbereitung von Bergbauhalden oder dem Recycling die relevanten Stoffe in den Ausgangsmaterialien in ihrer Zusammensetzung, Qualität und Quantität höchst inhomogen verteilt und weitgehend unbekannt sind. Die Intralogistik bei solchen Prozessen ist hochkomplex und muss daher bei der dynamischen Analyse des Ausgangsmaterials beginnen und mit Ergebnissen des Aufbereitungsprozesses enden. Die Steuerung des Aufbereitungsprozesses muss dynamisch und datengesteuert angepasst werden.
Am Beispiel der Aufbereitung von Haldenmaterial mit Hilfe der Flotation soll die Verknüpfung der Datenerfassung des Aufgabegutes mit der Prozesssteuerung, der Intralogisitk und weiteren Verarbeitungs- und Optimierungsschritten gezeigt werden.
Keywords: DigiFloat
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Lecture (Conference)
Finden statt Suchen – agieren statt reagieren, 24.11.2023, Chemnitz, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-37897
Publ.-Id: 37897
FlexiPlant
van den Boogaart, K. G.; Rau, F.
Mit der weltweit einmaligen Forschungsinfrastruktur FlexiPlant wollen wir Rohstoffe aller Art energie- und ressourceneffizient zurückgewinnen. Dafür entwickeln wir eine neue Generation adaptiver, flexibler & digitalisierter Aufbereitungstechnologien.
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Invited lecture (Conferences)
simul+Netzwerktreffen Kreislaufwirtschaft, 20.11.2023, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-37895
Publ.-Id: 37895
Changes to Captions: An Attentive Network for Remote Sensing Change Captioning
In recent years, advanced research has focused on the direct learning and analysis of remote-sensing images using natural language processing (NLP) techniques. The ability to accurately describe changes occurring in multi-temporal remote sensing images is becoming increasingly important for geospatial understanding and land planning. Unlike natural image change captioning tasks, remote sensing change captioning aims to capture the most significant changes, irrespective of various influential factors such as illumination, seasonal effects, and complex land covers. In this study, we highlight the significance of accurately describing changes in remote sensing images and present a comparison of the change captioning task for natural and synthetic images and remote sensing images. To address the challenge of generating accurate captions, we propose an attentive changes-to-captions network, called Chg2Cap for short, for bi-temporal remote sensing images. The network comprises three main components: 1) a Siamese CNN-based feature extractor to collect high-level representations for each image pair; 2) an attentive encoder that includes a hierarchical self-attention block to locate change-related features and a residual block to generate the image embedding; and 3) a transformer-based caption generator to decode the relationship between the image embedding and the word embedding into a description. The proposed Chg2Cap network is evaluated on two representative remote sensing datasets, and a comprehensive experimental analysis is provided. The code and pre-trained models will be available online at https://github.com/ShizhenChang/Chg2Cap .
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IEEE Transactions on Image Processing (2023)
Online First (2023) DOI: 10.1109/TIP.2023.3328224
Downloads
Permalink: https://www.hzdr.de/publications/Publ-37894
Publ.-Id: 37894
BDD-Net+: A Building Damage Detection Framework Based on Modified Coat-Net
Seydi, S. T.; Hasanlou, M.; Chanussot, J.; Ghamisi, P.
The accurate and fast assessment of damaged buildings following a disaster is critical for planning rescue and reconstruction efforts. The damage assessment by the traditional methods is time-consuming and with limited performance. In this article, we propose an end-to-end deep-learning network named building damage detection network-plus (BDD-Net+). The BDD-Net+ is based on a combination of convolution layers and transformer blocks. The proposed framework takes the advantage of the multiscale residual convolution blocks and self-attention layers. The proposed framework consists of four main steps: data preparation, model training, damage map generation and evaluation, and the use of an explainable artificial intelligence (XAI) framework for understanding and interpretation of the operation model. The experimental results include two representative real-world benchmark datasets (i.e., the Haiti earthquake and the Bata explosion). The obtained results illustrate that BDD-Net+ achieves excellent efficacy in comparison with other state-of-the-art methods. Furthermore, the visualization of the results by XAI shows that BDD-Net+ provides more interpretable and explainable results for damage detection than the other studied methods.
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IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 16(2023), 4232-4247
DOI: 10.1109/JSTARS.2023.3267847
Permalink: https://www.hzdr.de/publications/Publ-37893
Publ.-Id: 37893
X-ray Thomson Scattering as a high-precision tool for Warm Dense Matter diagnostics
Warm dense matter (WDM)---an extreme state that is characterized by extreme densities and
temperatures---has emerged as one of the most active frontiers in plasma physics and material
science. In nature, WDM occurs in astrophysical objects such as giant planet interiors and brown
dwarfs. In addition, WDM is highly important for cutting-edge technological applications such as
inertial confinement fusion and the discovery of novel materials. In the laboratory, WDM is studied
experimentally in large facilities around the globe, and new techniques have facilitated
unprecedented insights. Yet, the interpretation of these experiments requires a reliable diagnostics
based on accurate theoretical modeling, which is a notoriously difficult task [1].
In this talk, I will explain how we can use X-ray Thomson scattering (XRTS) measurements [2] to infer important system parameters such as the temperature, density, and degree of ionization. Interestingly, standard forward modeling methods based on the widespread Chihara decomposition have neglected transitions between free and bound electrons (the inverse process of the usual bound-free transitions), which are negligible at ambient conditions, but become important in the WDM regime [3]. In addition, I will show how switching to the imaginary-time representation opens up new avenues towards the model-free interpretation of XRTS signals, and gives one direct access to the temperature [4,5] and electronic correlations [6] of the system. Finally, I will outline new PIMC capabilities [7,8] that allow for quasi-exact simulations of experiments conducted at the Gbar platform at the National Ignition Facility (NIF) in Livermore.
[1] M. Bonitz et al, Physics of Plasmas 27, 042710 (2020)
[2] S. Glenzer and R. Redmer, Reviews of Modern Physics 81, 1625 (2009)
[3] M. Böhme et al, arXiv:2306.17653 (submitted)
[4] T. Dornheim et al, Nature Communications 13, 7911 (2022)
[5] T. Dornheim et al, Physics of Plasmas 30, 042707 (2023)
[6] T. Dornheim et al, arXiv:2305.15305 (submitted)
[7] M. Böhme et al, Physical Review Letters 129, 066402 (2022)
[8] T. Dornheim et al, Journal of Chemical Physics 159, 164113 (2023)
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Lecture (others)
GSI Plasmaphysik-Seminar, 28.11.2023, Darmstadt, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-37891
Publ.-Id: 37891
Hyperspectral Remote Sensing Benchmark Database for Oil Spill Detection With an Isolation Forest-Guided Unsupervised Detector
Duan, P.; Kang, X.; Ghamisi, P.; Li, S.
Oil spill detection has attracted increasing attention in recent years, since marine oil spill accidents severely affect environments, natural resources, and the lives of coastal inhabitants. Hyperspectral remote sensing images provide rich spectral information which is beneficial for the monitoring of oil spills in complex ocean scenarios. However, most of the existing approaches are based on supervised and semi-supervised frameworks to detect oil spills from hyperspectral images (HSIs), which require a massive amount of effort to annotate a certain number of high-quality training sets. In this study, we make the first attempt to develop an unsupervised oil spill detection method based on isolation forest (iForest) for HSIs. First, a Gaussian statistical model is designed to remove the bands corrupted by severe noise. Then, kernel principal component analysis (KPCA) is employed to reduce the high dimensionality of the HSIs. Next, the probability of each pixel belonging to one of the classes of seawater and oil spills is estimated with the iForest, and a set of pseudolabeled training samples is automatically produced using the clustering algorithm on the detected probability. Finally, an initial detection map can be obtained by performing the support vector machine (SVM) on the dimension-reduced data, and the initial detection result is further optimized with the extended random walker (ERW) model so as to improve the detection accuracy of oil spills. Experiments on hyperspectral oil spill database (HOSD) created by ourselves demonstrate that the proposed method obtains superior detection performance with respect to other state-of-the-art detection approaches. We will make HOSD and our developed library for oil spill detection publicly available at https://github.com/PuhongDuan/HOSD to further promote this research topic.
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IEEE Transactions on Geoscience and Remote Sensing 61(2023), 5509711
DOI: 10.1109/TGRS.2023.3268944
Cited 7 times in Scopus
Downloads
- Open Access Version from arxiv.org
- Secondary publication expected from 20.04.2024
Permalink: https://www.hzdr.de/publications/Publ-37889
Publ.-Id: 37889
Scalable machine learning for predicting the electronic structure in many-particle systems
In this presentation, I will present our recent progress in integrating machine learning to significantly boost the computational efficiency of electronic structure calculations [1]. I will specifically address our efforts to speed up density functional theory calculations, for which we have developed the Materials Learning Algorithms framework [2]. Our findings illustrate significant improvements in calculation speed for metals at their melting point. Additionally, our use of automated machine learning has yielded significant reductions in computational resources required to identify optimal neural network architectures, laying the groundwork for extensive investigations [3]. Furthermore, I will show the transferability of our ML model across temperatures [4]. Most importantly, I will present our latest breakthrough, which enables fast neural-network driven electronic structure calculations for systems unattainable by conventional density functional theory calculations [5].
References
[1] L. Fiedler, K. Shah, M. Bussmann, A. Cangi, Phys. Rev. Materials, 6, 040301 (2022).
[2] J. Ellis, L. Fiedler, G. Popoola, N. Modine, J. Stephens, A. Thompson, A. Cangi, S. Rajamanickam, Phys. Rev. B, 104, 035120 (2021).
[3] L. Fiedler, N. Hoffmann, P. Mohammed, G. Popoola, T. Yovell, V. Oles, J. Austin Ellis, S. Rajamanickam, A. Cangi, Mach. Learn.: Sci. Technol., 3, 045008 (2022).
[4] L. Fiedler, N. A. Modine, K. D. Miller, and A. Cangi Phys. Rev. B 108, 125146 (2023).
[5] L. Fiedler, N. Modine, S. Schmerler, D. Vogel, G. Popoola, A. Thompson, S. Rajamanickam, A. Cangi, npj. Comput. Mater., 9, 115 (2023).
Keywords: Machine learning; Electronic structure theory; Density functional theory; Neural networks
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Invited lecture (Conferences)
Many-Particle Systems under Extreme Conditions, WE-Heraeus Seminar and Max Born Symposium, 03.-06.12.2023, Görlitz, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-37883
Publ.-Id: 37883
Report on research data management interviews conducted for HMC Hub Energy in 2022
Ballani, F.; Schaller, T.; Steinmeier, L.; Koubaa, M. A.; Schweikert, J.; Stucky, K.-U.; Süß, W.
The Energy Hub of the Helmholtz Metadata Collaboration (HMC) conducted interviews with various stakeholders from the Helmholtz Research Field Energy on the topic of research data management (RDM) in 2022. The intentions were to build and serve a metadata community in the energy research field and to extend the Helmholtz-wide survey conducted by HMC in 2021 Arndt et al., 2022). Besides the deeper insight into the current state of RDM and metadata handling at the Helmholtz sites relevant to the Energy Hub the interviews focused on the related needs and difficulties of researchers and their satisfaction with the current state. Furthermore, we tried to discover already existing workflows and software solutions, to establish contacts and to make HMC better known.
Keywords: Helmholtz Metadata Collaboration; Research data management
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Other report
Karlsruhe, Deutschland: KITopen, 2023
7 Seiten
DOI: 10.5445/IR/1000164395
Permalink: https://www.hzdr.de/publications/Publ-37881
Publ.-Id: 37881
Data publication: Ion emission from warm dense matter produced by irradiation with a soft x-ray free-electron laser
Krása, J.; Burian, T.; Hájková, V.; Chalupský, J.; Jelínek, Š.; Frantálová, K.; Krupka, M.; Kuglerová, Z.; Kumar Singh, S.; Vozda, V.; Vyšín, L.; Smid, M.; Perez-Martin, P.; Kühlman, M.; Pintor, J.; Cikhardt, J.; Dreimann, M.; Eckermann, D.; Rosenthal, F.; Vinko, S. M.; Forte, A.; Gawne, T. D.; Campbell, T.; Ren, S.; Shi, Y.; Hutchinson, T.; Humphries, O. S.; Preston, T.; Makita, M.; Nakatsutsumi, M.; Pan, X.; Köhler, A.; Harmand, M.; Toleikis, S.; Falk, K.; Juha, L.
Data set on the ion emission of different materials. Each dataset is separate and titled with the chemical symbol or abbreviation of the specific material.
Related publications
- DOI: 10.1063/5.0157781 references this (Id 37880) publication
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Ion emission from warm dense matter produced by irradiation with a soft x-ray …
ROBIS: 37822 has used this (Id 37880) publication of HZDR-primary research data
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Reseach data in the HZDR data repository RODARE
Publication date: 2023-11-22 Closed access
DOI: 10.14278/rodare.2567
Versions: 10.14278/rodare.2568
Downloads
Permalink: https://www.hzdr.de/publications/Publ-37880
Publ.-Id: 37880
Effect of Chain Length on Swelling Transitions of Brodie Graphite Oxide in Liquid 1-Alcohols
Iakunkov, A.; Nordenström, A.; Boulanger, N.; Li, G.; Hennig, C.; Jørgensen, M. R. V.; Kantor, I.; Talyzin, . A. V.
Swelling is the most fundamental property of graphite oxides (GO). Here, a structural study of Brodie graphite oxide (BGO) swelling in a set of long chain 1-alcohols (named C11 to C22 according to the number of carbons) performed using synchrotron radiation X-ray diffraction at elevated temperatures is reported. Even the longest of tested alcohols (C22) is found to intercalate BGO with enormous expansion of the interlayer distance from ≈6Å up to ≈63Å, the highest expansion of GO lattice ever reported. Swelling transitions from low temperature alpha-phase to high temperature beta-phase are found for BGO in all alcohols in the C11–C22 set. The transitions correspond to decrease of inter-layer distance correlating with the length of alcohol molecules, and change in their orientation from perpendicular to GO planes to layered parallel to GO (Type II transitions). These transitions are very different compared to BGO swelling transitions (Type I) found in smaller alcohols and related to insertion/de-insertion of additional layer of alcohol parallel to GO. Analysis of general trends in the whole set of 1-alcohols (C1 to C22) shows that the 1-alcohol chain length defines the type of swelling transition with Type I found for alcohols with C<10 and Type II for C>10.
Related publications
- DOI: 10.1107/S1600577520014265 is cited by this (Id 37879) publication
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Advanced Materials Interfaces (2023), 2300554
DOI: 10.1002/admi.202300554
Permalink: https://www.hzdr.de/publications/Publ-37879
Publ.-Id: 37879
Ion Irradiation-Induced Sinking of Ag Nanocubes into Substrates
Choupanian, S.; Möller, W.; Seyring, M.; Pacholski, C.; Wendler, E.; Undisz, A.; Ronning, C.
Ion irradiation can cause burrowing of nanoparticles in substrates, strongly depending on the material properties and irradiation parameters. In this study, it is demonstrated that the sinking process can be accomplished with ion irradiation of cube-shaped Ag nanoparticles on top of silicon; how ion channeling affects the sinking rate; and underline the importance of the amorphous state of the substrate upon ion irradiation. Based on these experimental findings, the sinking process is described as being driven by capillary forces enabled by ion-induced plastic flow of the substrate.
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Advanced Materials (2023), 2300570
Online First (2023) DOI: 10.1002/admi.202300570
Permalink: https://www.hzdr.de/publications/Publ-37872
Publ.-Id: 37872
Experimentelle und rechnerische Bestimmung der Aktivierung für die Rückbauplanung von Kernkraftwerken
Barkleit, A.; Rachamin, R.; Pönitz, E.; Konheiser, J.
Vorstellung der FORKA-Projekte EMPRADO und WERREBA
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Lecture (Conference)
55. Kraftwerkstechnisches Kolloquium, 10.-11.10.2023, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-37871
Publ.-Id: 37871
Comparative structural and (radio-)chemical investigations of activated cement and concrete samples
Zilbermann, M. E.
To help with the decommissioning of the unit 2 of the Greifswald NPP, this study aims at determining the activities of 3H, 14C, 60Co, 152Eu and 154Eu in the concrete to estimate the maximal activity in the entire bioshield.
The study will focus on the activity as a function of depth in the concrete layer, as well as composition of the mineral phases. As the flux of neutrons generated during fission reaction encounters the mineral phases of concrete, the natural elements present in these phases absorb neutrons, which leads to the formation of their radioactive isotopes. Therefore, the elemental composition of each mineral phase in the concrete is important in the activation process, and the concrete being a heterogeneous material, different phases will present different activities.
A precise knowledge of the activities and of the elemental composition of the concrete and its mineral phases helps refining the models to calculate and predict the activities in a long-term scale. The calculations and the experimental results support the sorting of the materials for disposal.
This study will analyze the concrete with three main objectives:
- Activation;
- Chemical composition;
- Structure of the concrete and mineral phases.
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Master thesis
TU Dresden, 2023
Mentor: Prof. Dr. Thorsten Stumpf, Dr. Astrid Barkleit
Permalink: https://www.hzdr.de/publications/Publ-37870
Publ.-Id: 37870
On the missing single collision peak in low energy heavy ion scattering
Wilhelm, R. A.; Deuzeman, M. J.; Rai, S.; Husinsky, W.; Szabo, P. S.; Biber, H.; Stadlmayr, R.; Cupak, C.; Hundsbichler, J.; Lemell, C.; Möller, W.; Mutzke, A.; Hobler, G.; Versolato, O. O.; Aumayr, F.; Hoekstra, R.
We present experimental and simulation data on the oblique angle scattering of heavy Sn ions at 14 keV energy from a Mo surface. The simulations are performed with the binary collision approximation codes TRIM, TRIDYN, TRI3DYN, SDTrimSP, and IMSIL. Additional simulations were performed in the molecular dynamics framework with LAMMPS. Our key finding is the absence of an expected peak in the experimental energy spectrum of backscattered Sn ions associated with the pure single collision regime. In sharp contrast to this, however, all simulation codes we applied do show a prominent single collision signature both in the energy spectrum and in the angular scatter pattern. We discuss the possible origin of this important discrepancy and show in the process, that widely used binary collision approximation codes may contain hidden parameters important to know and to understand.
Keywords: Binary collision approximation; Heavy ions; Ion scattering; Molecular dynamics
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Nuclear Instruments and Methods in Physics Research B 544(2023), 165123
DOI: 10.1016/j.nimb.2023.165123
Permalink: https://www.hzdr.de/publications/Publ-37866
Publ.-Id: 37866
Post growth thermal treatments of Si1-x-yGexSny alloys
Steuer, O.; Schwarz, D.; Oehme, M.; Ganss, F.; Khan, M. M.; Cheng, Y.; Rebohle, L.; Zhou, S.; Helm, M.; Cuniberti, G.; Georgiev, Y.; Prucnal, S.
Si1-x-yGexSny alloys are promising materials for future applications in opto- and
nanoelectronics. These alloys enable effective band gap engineering, a broad
adjustability of the lattice parameter, exhibit much higher carrier mobility than pure Si
and are compatible with CMOS technology. Unfortunately, the equilibrium solid
solubility of Sn in Si1-xGex is less than 1% and pseudomorphic growth of Si1-xyGexSny
on Ge or Si causes in-plane compressive strain in the grown layer, which
degrades the superior properties of the alloys. Therefore, the post-growth strain
engineering using ultrafast non-equilibrium thermal treatments like flash lamp
annealing (FLA) or pulsed laser annealing (PLA) to improve the layer quality is
needed. In this contribution, we discuss the influence of millisecond FLA and
nanosecond PLA on Si1-x-yGexSny alloys and present an efficient way to improve
the layer quality of thin film Si1-x-yGexSny on insulator by PLA. Different Si1-xyGexSny
alloys are directly grown on commercial silicon-on-insulator (SOI) wafers
and treated by FLA or PLA. The material is analysed by micro-Raman spectroscopy,
Rutherford backscattering spectrometry (RBS) and X-ray diffraction (XRD) before
and after the thermal treatments. It is shown that after annealing, the material is
single-crystalline with much better crystallinity than the as-grown layer.
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 37864) publication
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Poster
E-MRS 2023 Spring Meeting, 29.05.-02.06.2023, Strasbourg, Frankreich
Permalink: https://www.hzdr.de/publications/Publ-37864
Publ.-Id: 37864
Aluminium substituted yttrium iron garnet thin films with reduced Curie temperature
Scheffler, D.; Steuer, O.; Zhou, S.; Siegl, L.; Goennenwein, S. T. B.; Lammel, M.
Magnetic garnets such as yttrium iron garnet (Y3 Fe 5 O12 , YIG) are widely used in spintronic and magnonic
devices. Their magnetic and magneto-optical properties can be modified over a wide range by tailoring their
chemical composition. Here, we report the successful growth of Al-substituted yttrium iron garnet (YAlIG) thin
films via radio frequency sputtering in combination with an ex situ annealing step. Upon selecting appropriate
process parameters, we obtain highly crystalline YAlIG films with different Al 3+ substitution levels on both
single crystalline Y 3 Al 5 O12 (YAG) and Gd 3 Ga 5 O12 (GGG) substrates. With increasing Al 3+ substitution levels,
we observe a reduction of the saturation magnetization as well as a systematic decrease of the magnetic ordering
temperature to values well below room temperature. YAlIG thin films thus provide an interesting material
platform for spintronic and magnonic experiments in different magnetic phases.
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 37860) publication
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Physical Review Materials 7(2023), 094405
DOI: 10.1103/PhysRevMaterials.7.094405
Permalink: https://www.hzdr.de/publications/Publ-37860
Publ.-Id: 37860
Comparando las estimaciones de selección de hábitat mediante modelos de distribución de especies y step selection functions
Recently, two methods of habitat selection have gained more relevance in the scientific literature: step selection functions (SSF) and MaxEnt. Despite their similarity these models are hardly ever used in the same context. The former is usually associated with studies based in movement ecology, and the latter is connected to species distribution modeling. Motivated by the difficulty in estimating habitat preferences using SSF, I compared the accuracy of predictions from both models based on movement data. As a case study, I utilized jaguar movement data from 5 countries in Latin American and created SSF and MaxEnt models based on climatic data and land use available from WorldClim and satellite imagery. I compared the accuracy of both types of models using the “Area Under Curve” (AUC) metric, on a separate subset of data. SSF models presented an average AUC of 0.5510 ± 0.0147 in comparison with 0.7544 ± 0.0185 of their MaxEnt equivalents. I believe those differences are partially caused by the convergence difficulties of SSF and conditional logistic regression. Consequently, I recommend the use of MaxEnt in predictive modelling, such as the ones needed in reserve and corridor design.
Keywords: Latin America; Jaguars; niche modelling; resource selection function; trajectory
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Ecosistemas 32(2023)2, 2455
Online First (2023) DOI: 10.7818/ECOS.2455
Cited 1 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-37859
Publ.-Id: 37859
Example data Publication Data Management Day
Fiedler, M.; Müller, S.; Knodel, O.
"This dataset is a multiyear mean Southern Ocean freshwater flux field that uses recently compiled measurements of ice sheet melting, iceberg calving, icerberg tracking, and river runoff"
Keywords: Test; Data; Publication; Data Management Day
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Reseach data in the HZDR data repository RODARE
Publication date: 2023-11-20 Open access
DOI: 10.14278/rodare.2564
Versions: 10.14278/rodare.2565
License: CC-BY-4.0
Downloads
Permalink: https://www.hzdr.de/publications/Publ-37854
Publ.-Id: 37854
Nontrivial Aharonov-Bohm effect and alternating dispersion of magnons in cone-state ferromagnetic rings
Uzunova, V.; Körber, L.; Kavvadia, A.; Quasebarth, G.; Schultheiß, H.; Kakay, A.; Ivanov, B.
Soft magnetic dots in the form of thin rings have unique topological properties. They can be in a vortex state with no vortex core. Here, we study the magnon modes of such systems both analytically and numerically. In an external magnetic field, magnetic rings are characterized by easy-cone magnetization and shows a giant splitting of doublets for modes with the opposite value of the azimuthal mode quantum number. The effect of the splitting can be refereed as a magnon analog of the topology-induced Aharonov-Bohm effect. For this we develop an analytical theory to describe the non-monotonic dependence of the mode frequencies on the azimuthal mode number, influenced by the balance between the local exchange and non-local dipole interactions.
Keywords: Spin waves; Topology; Vortex; Magnetism; Aharonov-Bohm effect; Micromagnetism
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Physical Review B 108(2023), 174445
DOI: 10.1103/PhysRevB.108.174445
Downloads
- Secondary publication expected from 29.11.2024
Permalink: https://www.hzdr.de/publications/Publ-37849
Publ.-Id: 37849
Using Julia to Accelerate Monte Carlo Event Generation with Neural Importance Sampling
Jungnickel, T.; Steiniger, K.; Bussmann, M.; Hernandez Acosta, U.
Monte Carlo event generation is essential for analysis in high energy physics and fast implementations are required to keep up with the large amounts of data measured by experiments. Therefore, these methods need to reflect the theoretical predictions accurately to enable efficient data generation, e.g. by rejection sampling. However, traditional importance sampling algorithms, such as the commonly used VEGAS algorithm, often struggle with adapting targets with multiple or non-coordinate aligned features, as is common in high energy physics. Especially in strong-field QED, processes dynamically depend on field parameters, which means the use of established codes for these problems needs to be questioned. An importance sampling approach using neural networks applied to strong-field processes is presented within the framework QED.jl. The quality of the generated proposals, e.g. the unweighting efficiency, is compared to VEGAS, providing insights beneficial to applications beyond strong-field QED.
Keywords: strong field QED; machine learning; Julia; QED.jl; neural importance sampling
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Lecture (Conference)
JuliaHEP 2023, 06.-09.11.2023, Erlangen, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-37848
Publ.-Id: 37848
Investigation of Mixing using Microfocus X-ray Computed Tomography (µCT)
Fine-grained solid particles from various industrial sources, which would otherwise be discarded, should ideally be processed to valuable products or inert residues. Among others, a) shredder fines from electronics and end-of-life vehicles, and b) flue dusts from non-ferrous metallurgical processes are of timely interest. They contain valuable residuals, such as metals, that can be returned to the industrial cycle instead of being landfilled. This is one aim of the Helmholtz project FINEST in which this work is embedded. In this work, mixing and agglomeration of such particles with a size below 1 mm are investigated for further use in the metallurgical industry. Different particle sizes and densities are considered. The process is observed experimentally using camera imaging technique and µCT. From the µCT images a mixing index is acquired. We present an experimental setup and methods for the aforementioned investigations.
Keywords: Microfocus X-Ray Computed Tomography; Particle Flow; Mixing and Segregation
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Lecture (Conference)
Bałdyga Technical Seminars - Mixing meets reality, 14.-15.09.2023, Berlin, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-37846
Publ.-Id: 37846
Accelerating Event Generation in Strong-Field QED with Neural Importance Sampling
Jungnickel, T.; Steiniger, K.; Hernandez Acosta, U.; Bussmann, M.
Efficient Monte Carlo integreation is crucial for modeling processes at the European XFEL. However, traditional approaches to importance sampling like VEGAS do not perform well when integrands display multiple features or non-coordinate aligned features. In this work, we present an implementation of neural importance sampling (NIS) in the Julia programming language to address this challenge. We demonstrate the effectiveness of NIS by applying it to processes in strong-field QED at high energies, showing superior adaption of the integrand and thus enabling efficient event generation.
Keywords: strong field QED; machine learning; Julia; QED.jl; neural importance sampling
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Poster
Helmholtz AI Conference 2023, 12.-14.06.2023, Hamburg, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-37845
Publ.-Id: 37845
Probing Iron in Earth's Core With Molecular-Spin Dynamics
Nikolov, S.; Ramakrishna, K.; Rohskopf, A.; Lokamani, M.; Tranchida, J.; Carpenter, J.; Cangi, A.; Wood, M. A.
Dynamic compression of iron to Earth-core conditions is one of the few ways to gather important elastic and transport properties needed to uncover key mechanisms surrounding the geodynamo effect. Herein a new machine-learned ab-initio derived molecular-spin dynamics (MSD) methodology with explicit treatment for longitudinal spin-fluctuations is utilized to probe the dynamic phase-diagram of iron. This framework uniquely enables an accurate resolution of the phase-transition kinetics and Earth-core elastic properties, as highlighted by compressional wave velocity and adiabatic bulk moduli measurements. In addition, a unique coupling of MSD with time-dependent density functional theory enables gauging electronic transport properties, critically important for resolving geodynamo dynamics.
Keywords: Molecular dynamics; Density functional theory; Machine Learning; Phase transitions; Geodynamo
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Contribution to WWW
https://doi.org/10.48550/arXiv.2311.08737
DOI: 10.48550/arXiv.2311.08737
Permalink: https://www.hzdr.de/publications/Publ-37844
Publ.-Id: 37844
Critical review on production, characterization and applications of microalgal hydrochar: Insights on circular bioeconomy through hydrothermal carbonization
Supraja, K. V.; Doddapaneni, T. R. K. C.; Ramasamy, P. K.; Kaushal, P.; Ahammad, S. Z.; Pollmann, K.; Jain, R.
Exploitation of microalgal biomass as a valuable resource is hindered by the challenges associated with high downstream
processing costs, including biomass harvesting, drying, and product extraction. Direct utilization of microalgae as a solid fuel
source, soil conditioner, capacitor or adsorbent material raises environmental concerns. Hydrothermal carbonization (HTC)
is a highly efficient and promising technology for microalgal biomass conversion. This comprehensive review provides an indepth
understanding of the HTC reaction mechanisms involved in microalgal hydrochar production, shedding light on the
underlying processes and factors affecting the quality of hydrochar. HTC has the potential to improve fixed carbon content,
thermal stability and nutrient availability in the resulting hydrochar. Furthermore, this review explores the integration of HTC
with anaerobic digestion (AD) to establish a circular bioeconomy, thereby promoting sustainability in energy generation. The
synergistic combination offers a promising approach for the efficient utilization of microalgal biomass, where hydrochar can
serve as a renewable energy source while the aqueous fraction can be utilized as a nutrient-rich feedstock for biogas
production. By highlighting the potential benefits and futuristic directives associated with microalgal biomass valorisation
through HTC, this review aims to contribute to the development of sustainable waste management strategies for recovery of
value-added compounds from microalgae. Ultimately, this review strives to foster the transition towards a more
environmentally friendly and resource-efficient bioeconomy.
Keywords: Algae; Anaerobic digestion; Bioconversion; Biomass; Carbonization; Microorganisms; Nutrients; Soils
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Chemical Engineering Journal 473(2023), 145059
DOI: 10.1016/j.cej.2023.145059
Downloads
- Secondary publication expected from 01.10.2024
Permalink: https://www.hzdr.de/publications/Publ-37842
Publ.-Id: 37842
Rohstoffe und Ressourcen
Im Vortrag geht es um Resourcen und Rohstoffe, Einteilung, Kritikalität, circular economy, Recycling und Alternativen, sowie als Beispiel um Seltene Erden
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Lecture (others)
Schulische Veranstaltung, 27.10.2023, Chemnitz, Montessori-Gymnasium, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-37839
Publ.-Id: 37839
Mineralogy, Geochemistry, and Genesis of Agates from Chihuahua, Northern Mexico
Mrozik, M.; Götze, J.; Pan, Y.; Möckel, R.
The present study aimed to investigate the genesis and characteristics of some of the world-famous agate deposits in the state of Chihuahua, Mexico (Rancho Coyamito, Ojo Laguna, Moctezuma, Huevos del Diablo, Agua Nueva). Geochemical and textural studies of host rocks showed that all the studied deposits are related to the same rock type within the geological unit of Rancho el Agate andesite, a quartz-free latite that shows clear indications of magma mixing. As a result of their large-scale distribution and various differentiation processes, as well as transport separation, different textures and local chemical differences between rocks of different localities can be observed. These differences have also influenced the properties of SiO2 mineralization in the rocks. The mixing of near-surface fluids from rock alterations with magmatic hydrothermal solutions led to the accumulation of various elements in the SiO2 matrix of the agates, which were, on the one hand, mobilized during secondary rock alteration (Fe, U, Ca, K, Al, Si) and, on the other hand, transported with magmatic fluids (Zn, Sb, Si, Zr, Cr). Different generations of chalcedony indicate a multi-stage formation as well as multiple cycles of filling the cavities with fluids. The hydrothermal fluids are presumably related to the residual solutions of a rhyolitic volcanism, which followed the latitic extrusions in the area and probably caused the formation of polymetallic ore deposits in the Chihuahua area. The enrichment of highly immobile elements indicates the involvement of volatile fluids in the agate formation. The vivid colors of the agates are almost exclusively due to various mineral inclusions, which consist mainly of iron compounds.
Keywords: agate; chalcedony; trace elements; EPR spectroscopy; silica minerals; agate colors; cathodoluminescence; geology; Rancho Coyamito; Ojo laguna; Moctezuma; Agua Nueva
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Minerals 13(2023)5, 687
DOI: 10.3390/min13050687
Permalink: https://www.hzdr.de/publications/Publ-37838
Publ.-Id: 37838
A new approach to model the fluid dynamics in sandwich packings
Franke, P.; Shabanilemraski, I.; Schubert, M.; Hampel, U.; Kenig, E. Y.
Sandwich packings represent new separation column internals, with a potential to intensify mass
transfer. They comprise two conventional structured packings with different specific geometrical surface areas.
In this work, the complex fluid dynamics in sandwich packings is modeled using a novel approach based on a onedimensional,
steady momentum balance of the liquid and gas phases. The interactions between the three present
phases (gas, liquid, and solid) are considered by closures incorporated into the momentum balance. The
formulation of these closures is derived from two fluid-dynamic analogies for the film and froth flow patterns.
The adjustable parameters in the closures are regressed for the film flow using dry pressure drop measurements
and liquid hold-up data in trickle flow conditions. For the froth flow, the tuning parameters are fitted to overall
pressure drop measurements and local liquid hold-up data acquired from ultra-fast X-ray tomography (UFXCT).
The model predicts liquid hold-up and pressure drop data with an average relative deviation of 16.4 % and 19 %,
respectively. Compared to previous fluid dynamic models for sandwich packings, the number of adjustable
parameters could be reduced while maintaining comparable accuracy.
Keywords: sandwich packings; modeling; tomography; fluid dynamics
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Chemical Product and Process Modeling (2023)
Online First (2023) DOI: 10.1515/cppm-2023-0054
Downloads
Permalink: https://www.hzdr.de/publications/Publ-37836
Publ.-Id: 37836
Data publication: Fluid Transport in Ordinary Portland Cement and Slag Cement from in-situ Positron Emission Tomography
Reiss, A.; Kulenkampff, J.; Fischer, C.
RelatedPerson: Gruhne, Stefan; RelatedPerson: Lösel, Dagmar; RelatedPerson: Schößler, Claudia
Supplemental Primary PET Data to Fluid Transport in Ordinary Portland Cement and Slag Cement from in-situ Positron Emission Tomography Reiss, A.; Kulenkampff, J.; Bar-Nes, G.; Fischer, C.; Emmanuel, S. Submitted to Cement and Concrete Research 02.11.24 Material and procedure are characterized in the paper. PET data are supplied in Interfile format (Original: Cradduck T.D., Bailey D.L., Hutton BF, Deconinck F., Busemann Sokole E., Bergmann H., Noelpp U.: “A standard protocol for the exchange of nuclear medicine image files. Nucl Med Commun; 10:703-713 (1989), used version: https://stir.sourceforge.net/links/petinterfile03.pdf). The interfile format includes an ASCII header file (.hv) and a binary file containing the volume data (.v). Import filters exist for many visualization frameworks (e.g. Matlab, Avizo); otherwise the binary data files can be imported as raw data, taking into account the format given in the header file. The header tags were extended for relevant experimental parameters of non-medical PET experiments and in this way serve as experimental protocol. List of data files: cem1_F-18.7z: 17 PET frames from the 18F intrusion experiment cem1_Cu-64.7z: 31 PET frames from the 64Cu intrusion experiment cem1_I-124.7z: 34 PET frames from the 124I intrusion experiment The PET data sets (LMFs) were acquired with a tilted ClearPET-scanner (Elysia-Raytest) with a vertical axis of the cylindrical FOV at HZDR. The “trues”-projections were corrected for attenuation and scatter with a procedure based on the STIR-library (https://stir.sourceforge.net, version 3.0, Kris Thielemans, Charalampos Tsoumpas, Sanida Mustafovic, Tobias Beisel, Pablo Aguiar, Nikolaos Dikaios, and Matthew W Jacobson, STIR: Software for Tomographic Image Reconstruction Release 2, Physics in Medicine and Biology, 57 (4), 2012 pp.867-883).
Keywords: Positron Emission Tomography (PET); Imbibition; Cement paste; Fluid transport
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Reseach data in the HZDR data repository RODARE
Publication date: 2023-11-15 Restricted access
DOI: 10.14278/rodare.2554
Versions: 10.14278/rodare.2555
Downloads
Permalink: https://www.hzdr.de/publications/Publ-37835
Publ.-Id: 37835
Large-Scale Formation of DNA Origami Lattices on Silicon
Tapio, K.; Kielar, C.; Parikka, J. M.; Keller, A.; Järvinen, H.; Fahmy, K.; Jussi Toppari, J.
In recent years, hierarchical nanostructures have found applications in fields like diagnostics, medicine, nano-optics, and nanoelectronics, especially in challenging applications like the creation of metasurfaces with unique optical properties. One of the promising materials to fabricate such nanostructures has been DNA due to its robust self-assembly properties and plethora of different functionalization schemes. Here, we demonstrate the assembly of a two-dimensional fishnet-type lattice on a silicon substrate using cross-shaped DNA origami as the building block, i.e., tile. The effects of different environmental and structural factors are investigated under liquid atomic force microscopy (AFM) to optimize the lattice assembly. Furthermore, the arm-to-arm binding affinity of the tiles is analyzed, revealing preferential orientations. From the liquid AFM results, we develop a methodology to produce closely-spaced DNA origami lattices on silicon substrate, which allows further nanofabrication process steps, such as metallization. This formed polycrystalline lattice has high surface coverage and is extendable to the wafer scale with an average domain size of about a micrometer. Further studies are needed to increase the domain size toward a single-crystalline large-scale lattice.
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Chemistry of Materials 35(2023)5, 1961-1971
Online First (2023) DOI: 10.1021/acs.chemmater.2c03190
Cited 4 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-37834
Publ.-Id: 37834
Pulsed interactions unify reaction-diffusion and spatial nonlocal models for biological pattern formation
Colombo, E. H.; Martinez Garcia, R.; Calabrese, J.; López, C.; Hernández-García, E.
The emergence of a spatially-organized population distribution depends on the dynamics of the population and mediators of interaction (activators and inhibitors). Two broad classes of models have been used to investigate when and how self-organization is triggered, namely, reaction-diffusion and spatially nonlocal models. Nevertheless, these models implicitly assume smooth propagation scenarios, neglecting that individuals many times interact by exchanging short and abrupt pulses of the mediating substance. A recently proposed framework advances in the direction of properly accounting for these short-scale fluctuations by applying a coarse-graining procedure on the pulse dynamics. In this paper, we generalize the coarse-graining procedure and apply the extended formalism to new scenarios in which mediators influence individuals' reproductive success or their motility. We show that, in the slow- and fast-mediator limits, pulsed interactions recover, respectively, the reaction-diffusion and nonlocal models, providing a mechanistic connection between them. Furthermore, at each limit, the spatial stability condition is qualitatively different, leading to a timescale-induced transition where spatial patterns emerge as mediator dynamics becomes sufficiently fast.
Keywords: self-organization; population dynamics; pattern formation; animal communication
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Contribution to WWW
https://arxiv.org/abs/2311.07135
Permalink: https://www.hzdr.de/publications/Publ-37832
Publ.-Id: 37832
Preparation of Volborthite by a Facile Synthetic Chemical Solvent Extraction Method
Sánchez-Loredo, M. G.; Palomares-Sánchez, S. A.; Labrada-Delgado, G. J.; Helbig, T.; Chekhonin, P.; Ebert, D.; Möckel, R.; Owusu Afriyie, J.; Kelly, N.
In this work, the extraction of vanadium (V) ions from an alkaline solution using a commercial quaternary ammonium salt and the production of metal vanadates through precipitation stripping were carried out. The crystallization of copper vanadates from the extracts was performed using a solution containing a copper(II) source in concentrated chloride media as a stripping agent. In an attempt to control growth, a stabilizing polymer (polyvinylpyrrolidone, PVP) was added to the stripping solution. The structural characteristics of the crystallized products, mainly copper pyrovanadate (volborthite, Cu3V2O7(OH)2·(H2O)2) nanoflakes and nanoflowers and the experimental parameter influencing the efficiency of the stripping process were studied. From the results, the synthesis of nanostructured vanadates is a simple and versatile method for the fabrication of valuable three-dimensional structures providing abundant active zones for energy and catalytic applications.
Keywords: vanadium(V) extraction; anion exchange; quaternary ammonium salt; precipitation stripping; nanostructured vanadates; volborthite; polyvinylpyrrolidone
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Nanomaterials 13(2023), 1977
DOI: 10.3390/nano13131977
Permalink: https://www.hzdr.de/publications/Publ-37830
Publ.-Id: 37830
Geochemistry and formation of agate-bearing lithophysae in Lower Permian volcanics of the NW-Saxonian Basin (Germany)
Götze, J.; Möckel, R.; Pan, Y.; Müller, A.
Geochemical and mineralogical investigations of the Lower Permian Kemmlitz rhyolite within the NW-Saxonian Basin
(Germany) and associated lithophysae (high-temperature crystallization domains) as well as agates were carried out to
constrain the genesis and characteristics of these volcanic rocks and the origin of the agate-bearing lithophysae. The
volcanic rocks of rhyolitic composition are dominated by quartz, sanidine, and orthoclase and most likely derive from lava
flows. Agate-bearing lithophysae were exclusively formed in a glassy facies (pitchstone) of the rhyolites, which was
afterwards altered to illite-smectite mixed-layer clays. The results of this study show that agate formation can be related to
the alteration of the volcanic rocks accompanied by the infill of mobilized silica into cavities of lithophysae. Fluid inclusion
studies point to temperatures of agate formation above 150 °C, indicating that the mobilization and accumulation of silica
started already during a late phase of or soon after the volcanic activities. Remarkable high concentrations of B (29 ppm),
Ge (> 18 ppm), and U (> 19 ppm) as well as chondrite-normalized rare earth element (REE) distribution patterns of the
agates with pronounced negative Eu-anomalies, slightly positive Ce-anomalies and enriched heavy rare earth elements
(HREE) indicate interactions of the host rocks and transport of SiO2 with magmatic volatiles (F/Cl, CO2) and heated
meteoric water. Characteristic yellow cathodoluminescence (CL), heterogeneous internal textures as well as high defect
density of micro- and macrocrystalline quartz detected by electron paramagnetic resonance (EPR) spectroscopy point to
crystallization processes via an amorphous silica precursor under non-equilibrium conditions.
Keywords: Agate; Geochemistry; Lithophysae; Permian rhyolites; Quartz
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Mineralogy and Petrology (2023)
Online First (2023) DOI: 10.1007/s00710-023-00841-2
Permalink: https://www.hzdr.de/publications/Publ-37829
Publ.-Id: 37829
Pages: [1.] [2.] [3.] [4.] [5.] [6.] [7.] [8.] [9.] [10.] [11.] [12.] [13.] [14.] [15.] [16.] [17.] [18.] [19.] [20.] [21.] [22.] [23.] [24.] [25.] [26.] [27.] [28.] [29.] [30.] [31.] [32.] [33.] [34.] [35.] [36.] [37.] [38.] [39.] [40.] [41.] [42.] [43.] [44.] [45.] [46.] [47.] [48.] [49.] [50.] [51.] [52.] [53.] [54.] [55.] [56.] [57.] [58.] [59.] [60.] [61.] [62.] [63.] [64.] [65.] [66.] [67.] [68.] [69.] [70.] [71.] [72.] [73.] [74.] [75.] [76.] [77.] [78.] [79.] [80.] [81.] [82.] [83.] [84.] [85.] [86.] [87.] [88.] [89.] [90.] [91.] [92.] [93.] [94.] [95.] [96.] [97.] [98.] [99.] [100.] [101.] [102.] [103.] [104.] [105.] [106.] [107.] [108.] [109.] [110.] [111.] [112.] [113.] [114.] [115.] [116.] [117.] [118.] [119.] [120.] [121.] [122.] [123.] [124.] [125.] [126.] [127.] [128.] [129.] [130.] [131.] [132.] [133.] [134.] [135.] [136.] [137.] [138.] [139.] [140.] [141.] [142.] [143.] [144.] [145.] [146.] [147.] [148.] [149.] [150.] [151.] [152.] [153.] [154.] [155.] [156.] [157.] [158.] [159.] [160.] [161.] [162.] [163.] [164.] [165.] [166.] [167.] [168.] [169.] [170.] [171.] [172.] [173.] [174.] [175.] [176.] [177.] [178.] [179.] [180.] [181.] [182.] [183.] [184.] [185.] [186.] [187.] [188.] [189.] [190.] [191.] [192.] [193.] [194.] [195.] [196.] [197.] [198.] [199.] [200.] [201.] [202.] [203.] [204.] [205.] [206.] [207.] [208.] [209.] [210.] [211.] [212.] [213.] [214.] [215.] [216.] [217.] [218.] [219.] [220.] [221.] [222.] [223.] [224.] [225.] [226.] [227.] [228.] [229.] [230.] [231.] [232.] [233.] [234.] [235.] [236.] [237.] [238.] [239.] [240.] [241.] [242.] [243.] [244.] [245.] [246.] [247.] [248.] [249.] [250.] [251.] [252.] [253.] [254.] [255.] [256.] [257.] [258.] [259.] [260.] [261.] [262.] [263.] [264.] [265.] [266.] [267.] [268.] [269.] [270.] [271.] [272.] [273.] [274.] [275.] [276.] [277.] [278.] [279.] [280.] [281.] [282.] [283.] [284.] [285.] [286.] [287.] [288.] [289.] [290.] [291.] [292.] [293.] [294.] [295.] [296.] [297.] [298.] [299.] [300.] [301.] [302.] [303.] [304.] [305.] [306.] [307.] [308.] [309.] [310.] [311.] [312.] [313.] [314.] [315.] [316.] [317.] [318.] [319.] [320.] [321.] [322.] [323.] [324.] [325.] [326.] [327.] [328.] [329.] [330.] [331.] [332.] [333.] [334.] [335.] [336.] [337.] [338.] [339.] [340.] [341.]