Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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41396 Publications

On the application of advanced modeling tools to the SLB analysis in NuScale. Part I: TRACE/PARCS, TRACE/PANTHER and ATHLET/DYN3D

Sanchez-Torrijos, J.; Redondo-Valero, E.; Queral, C.; Cabellos, O.; Meca, R.; Petrásek, O.; Diaz Pescador, E.; Kliem, S.; Palmans, N.; Sanchez-Espinoza, V.

Nowadays, there is a growing interest in the Small Modular Reactors (SMRs) technology due to their enhanced safety level and reasonably reduced manufacturing and construction costs. However, modeling tools should be able to deal with the special features inherent to their design such as the modeling of the helical Steam Generators. In this work, a Steam Line Break sequence in the NuScale reactor has been simulated using several modeling tools based on a full-plant thermohydraulic model for a system code coupled with a 3D nodal diffusion code for describing the core physics. To do so, four different models have been developed by four different organization for the coupled codes TRACE/PARCS, TRACE/PANTHER and ATHLET/DYN3D. In that sense, a very reasonable agreement is reached among the steady-state parameters of the plant computed by each participant and the ones presented in the Design Standard Application Report of NuScale. Regarding the simulation of the SLB transient, it should be noted that after 100 seconds of simulation, it can be said that remarkable differences are to be seen among the results for the time behavior of the core temperatures. Those differences are attributable to differences in the heat transfer within the helically coiled steam generators. Important differences have been also found in the decay heat removal system performance, so it is concluded that further investigation and model development is needed for the phenomena occurring in the steam generators and the decay heat removal heat system.

Keywords: NuScale; McSAFER; Steam Line Break; Coupled codes

  • Contribution to proceedings
    2023 International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering, M&C 2023, 13.-17.08.2023, Niagara Falls, Canada
    Proceedings of the 2023 International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering, M&C 2023, 978-1-926773-50-6
  • Lecture (Conference)
    2023 International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering, M&C 2023, 13.-17.08.2023, Niagara Falls, Canada

Permalink: https://www.hzdr.de/publications/Publ-37428
Publ.-Id: 37428


Review and recommendations on deformable image registration uncertainties for radiotherapy applications

Nenoff, L.; Amstutz, F.; Murr, M.; Archibald-Heeren, B.; Fusella, M.; Hussein, M.; Lechner, W.; Zhang, Y.; Sharp, G.; Vasquez Osorio, E.

Deformable image registration (DIR) is a versatile tool used in many applications in radiotherapy (RT). DIR algorithms have been implemented in many commercial treatment planning systems providing accessible and easy-to-use solutions. However, the geometric uncertainty of DIR can be large and difficult to quantify, resulting in barriers to clinical practice. Currently, there is no agreement in the RT community on how to quantify these uncertainties and determine thresholds that distinguish a good DIR result from a poor one. This review summarises the current literature on sources of DIR uncertainties and their impact on RT applications. Recommendations are provided on how to handle these uncertainties for patient-specific use, commissioning, and research. Recommendations are also provided for developers and vendors to help users to understand DIR uncertainties and make the application of DIR in RT safer and more reliable.

Keywords: deformable image registration; DIR uncertainty; radiotherapy; structure propagation; dose accumulation; mapping; image deformation

Permalink: https://www.hzdr.de/publications/Publ-37427
Publ.-Id: 37427


CEFR control rod drop transient simulation using RAST-F code system

Tran, T. Q.; Huo, X.; Fridman, E.; Lee, D.

This study aimed to verify and validate the transient simulation capability of the hybrid code system RAST-F for fast reactor analysis. For this purpose, control rod (CR) drop experiments of eight CRs and six control groups in the China Experimental Fast Reactor (CEFR) start-up tests were utilized to simulate the CR drop transient. The RAST-F numerical solution, including the neutron population, time-dependent reactivity, and CR worth, was compared against the measurement values obtained from two out-of-core detectors. Moreover, the time-dependent reactivity and CR worth from RAST-F were verified against the results obtained by the Monte Carlo code Serpent using continuous energy nuclear data. A code-to-code comparison between Serpent and RAST-F showed good agreement in terms of time-dependent reactivity and CR worth. The discrepancy was less than 160 pcm for reactivity and less than 110 pcm for CR worth. RAST-F solution was almost identical to the measurement data in terms of neutron population and reactivity. All the calculated CR worth results agreed with experimental results within two standard deviations of experimental uncertainty for all CRs and control groups. This work demonstrates that the RAST-F code system can be a potential tool for analyzing time-dependent phenomena in fast reactors.

Keywords: CEFR; RAST-F; Transient; Nodal diffusion code; Serpent

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Permalink: https://www.hzdr.de/publications/Publ-37426
Publ.-Id: 37426


Prompt gamma-ray spectroscopy in conjunction with the Monte Carlo Library Least Squares approach: applications to range verification in proton therapy

Skjerdal, K.; Kögler, T.; Lionheart, W.; Smeland Ytre-Hauge, K.; Meric, I.

Prompt Gamma-ray Spectroscopy (PGS) in conjunction with the Monte Carlo Library Least Squares (MCLLS) approach was investigated for the purposes of range monitoring in proton therapy through Monte Carlo simulations. Prompt gamma-rays are produced during treatment and can be correlated to the range of the proton beam in the tissue. In contrast to established approaches, MCLLS does not rely on the identification of specific photopeaks. Instead it treats each individual constituent as a library spectrum and calculates coefficients for each spectrum, and therefore takes both the photopeaks and the Compton continuum into account. It can thus be applied to organic scintillators traditionally not used for energy spectroscopy due to their low Z number and density. Preliminary results demonstrate that the proposed approach returns a strong linear correlation between the range of the primary proton beam and the calculated library coefficients, depending on the composition of libraries. This can be exploited for range monitoring.

Keywords: proton therapy; spectroscopy; Monte Carlo simulations; range verification

Related publications

  • Open Access Logo Contribution to proceedings
    ANIMMA 2023 – Advancements in Nuclear Instrumentation Measurement Methods and their Applications, 12.-16.06.2023, Real Collegio, Italy
    ANIMMA 2023 Conference Proceedings: EPJ Web of Conferences
    DOI: 10.1051/epjconf/202328809003

Permalink: https://www.hzdr.de/publications/Publ-37424
Publ.-Id: 37424


Morphology and orientation change of layer-by-layer deposited one- and two-dimensional coordination polymer nanocrystals containing rhodium paddle-wheel units

Steinbach, D.; Neubert, R.; Gersdorf, S.; Schimpf, C.; Erb, D.; Rafaja, D.; Plamper, F. A.; Mertens, F.

Surface-directed and preferentially oriented assemblies of nanomaterials can enable enhanced applications in e.g. catalysis or sensing. Coordination polymers, which can be even conducting, could be suitable materials for this purpose because of their facile surface anchoring. Hence, we coassembled rhodium paddle-wheel building blocks with bi- or trifunctional linkers in dip coatings that were produced by layer-by-layer approach on silicon wafers functionalized by thin nanocrystalline gold surfaces. These gold surfaces were decorated with a self-assembled monolayer (SAM) for coordination and binding to the Rh-units. As linkers, pyrazine, triazine and melamine were used, leading to rectangularly-shaped, hexagonally-shaped or needle-like crystals, respectively. The coordination polymers were produced by repeated dipping into the linker and paddle-wheel solution, each followed by a cleaning step. The crystals growth was followed by atomic force microscopy (AFM) grazing incidence small-angle X-ray scattering (GISAXS) and grazing incidence wide-angle X-ray scattering (GIWAXS). AFM and GISAXS revealed the shape and size of the crystals. GIWAXS disclosed their preferred orientation. It turned out that the automated dipping procedure does not lead to a strong alignment of crystallites along the dipping direction for the pyrazine-based deposits. However, these crystals are preferentially oriented with respect to the substrate normal direction. The crystallographic direction and the degree of the alignment depend on the number of deposition cycles. In the early phases of the deposition process, predominantly “lying” crystals were detected. With increasing number of the deposition cycles, the fraction of “standing” crystals became dominant. These crystals are oriented with their {010} directions perpendicular to the surface of the substrate. Still, “lying” and some tilted crystals were detected additionally. The study gives a deeper structural understanding of crystallite assemblies and suggests an evolvement of more anisotropic orientations of the crystallites with increasing deposition cycles (leading to the prevalence of crystals having the preferred {010} orientation with respect to the surface normal direction).

Permalink: https://www.hzdr.de/publications/Publ-37423
Publ.-Id: 37423


Overcoming stereological Bias: A workflow for 3D mineral characterization of particles using X-ray micro-computed tomography

Siddique, A.; Da Assuncao Godinho, J. R.; Sittner, J.; Pereira, L.

Mineral separation processes operate on properties of individual particle, which can currently be quantified with 2D
characterization techniques, namely 2D automated mineralogy. While 2D automated mineralogy data have driven significant
developments in particle-based separation models, this data inherently correspond to 2D slices of 3D objects, which leads to
stereological bias in the quantification of geometric particle properties. X-ray micro-computed tomography (μCT) is a 3D
imaging technique that can quantify particle geometry. However, μCT only collects limited information regarding material
composition, making mineral identification quantification a challenge. To overcome this challenge, we present a workflow
that utilizes individual particle histograms and corrects image artefacts caused by μCT measurements, such as partial
volume effect. We demonstrate the application of the workflow to perform 3D mineral characterisation of a sulfidic gold ore,
where mineral phases that are commonly mistaken with μCT could be distinguished: pyrite and chalcopyrite, gold, and
galena. Results were verified by comparison with inductively coupled plasma mass spectrometry and 2D automated
mineralogy. As a result, the workflow provides the user with a detailed 3D particle dataset containing the modal mineralogy
and surface compositions, size, and geometrical properties of each particle in a sample – essential data for modelling
mineral separation processes.

Keywords: 2D automated mineralogy; 3D mineral characterization; Individual particle histograms; Mineral separation processes; X-ray micro-computed tomography

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  • Secondary publication expected from 28.04.2024

Permalink: https://www.hzdr.de/publications/Publ-37422
Publ.-Id: 37422


Highly Enhanced Defects Driven Room Temperature Ferromagnetism in Mixed-phase MoS2-MoOx Films

Singh, P.; Ghosh, S.; Jain, M.; Singh, A.; Singh, R.; Balal, M.; Roy Barman, S.; Kentsch, U.; Zhou, S.; Bhattacharya, S.; Srivastava, P.

Room temperature ferromagnetism has been reported in chemical vapor deposition-grown mixed-phase MoS2-MoOx thin films after Xe ion irradiation. Magnetic moment has significantly been enhanced after ion irradiation. Deterioration in crystallinity after ion irradiation has been shown by X-ray diffraction and Raman spectroscopy measurements. The variation in the surface morphology and/or formation of edge states can be observed by secondary electron microscopy images. The reduction in the oxygen vacancy concentration, probed by analysis of the O 1s core level X-ray photoelectron spectrum for the film with the maximum magnetic moment, rules out the possibility of ferromagnetism due to oxygen vacancy. Enhancement in the Mo content in 5+ and 6+ oxidation states due to the occupation of sulfur vacancy sites by oxygen after ion irradiation, calculated from X-ray photoelectron spectroscopy core level of Mo 3d and S 2p and valence band spectra, has been observed. Density functional theory (DFT) calculations also show the one-to-one correspondence of saturation magnetic moment with Mo6+ content. So, the enhancement in the ferromagnetism in mixed-phase of MoS2-MoOx thin films is due to the increase of Mo in 6+ oxidation state and exchange interaction between the different oxidation states of Mo via p-orbital of anion and formation of edged states.

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Permalink: https://www.hzdr.de/publications/Publ-37421
Publ.-Id: 37421


Ion irradiation of monolayer graphene-Nd:YAG hybrid waveguides: fabrication and laser

Ma, L.; Li, S.; Wang, H.; Zhou, S.; Yang, T.

Hybrid waveguides consisting of two-dimensional layered materials pad on the surface of optical waveguides suffer from a nonuniform and loose contact between the two-dimensional material and the waveguide, which can reduce the efficiency of the pulsed laser. Here, we present high-performance passively Q-switched pulsed lasers in three distinct structures of monolayer graphene-Nd:YAG hybrid waveguides irradiated by energetic ions. The ion irradiation enables the monolayer graphene a tight contact and strong coupling with the waveguide. As a result, Q-switched pulsed lasers with narrow pulse width and high repetition rate are obtained in three designed hybrid waveguides. The narrowest pulse width is 43.6 ns, provided by the ion-irradiated Y-branch hybrid waveguide. This study paves the way toward developing on-chip laser sources based on hybrid waveguides by using ion irradiation.

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Permalink: https://www.hzdr.de/publications/Publ-37420
Publ.-Id: 37420


Ferromagnetic interlayer coupling in CrSBr crystals irradiated by ions

Long, F.; Ghorbani Asl, M.; Mosina, K.; Li, Y.; Lin, K.; Ganss, F.; Hübner, R.; Sofer, Z.; Dirnberger, F.; Kamra, A.; Krasheninnikov, A.; Prucnal, S.; Helm, M.; Zhou, S.

Layered magnetic materials are becoming a major platform for future spin-based applications. Particularly the air-stable van der Waals compound CrSBr is attracting considerable interest due to its prominent magneto-transport and magneto-optical properties. In this work, we observe a transition from antiferromagnetic to ferromagnetic behavior in CrSBr crystals exposed to high-energy, non-magnetic ions. Already at moderate fluences, ion irradiation induces a remanent magnetization with hysteresis adapting to the easy-axis anisotropy of the pristine magnetic order up to a critical temperature of 110 K. Structure analysis of the irradiated crystals in conjunction with density functional theory calculations suggest that the displacement of constituent atoms due to collisions with ions and the formation of interstitials favors ferromagnetic order between the layers.

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Permalink: https://www.hzdr.de/publications/Publ-37419
Publ.-Id: 37419


[18F]RM273 – A PET probe for the imaging of the sigma2 receptor in brain cancer

Gündel, D.; Toussaint, M.; Moldovan, R.-P.; Teodoro, R.; Schepmann, D.; Wünsch, B.; Ludwig, F.-A.; Fischer, S.; Brust, P.; Deuther-Conrad, W.

The sigma2 receptor (TMEM97) expression correlates well with the Ki67 expression in tumours [1, 2] and therefore represents an attractive marker for the proliferative status. We developed the 18F-labelled radioligand [18F]RM273 for sigma2 receptor imaging in brain tumours.
[18F]RM273 (2-[4-(6-[18F]fluoro-1H-pyrrolo[2,3-b]pyridin-1-yl)butyl]-6,7-dimethoxy-1,2,3,4-tetra-hydroisoquinoline) has been obtained by automated synthesis by Cu-mediated oxidative radiofluorination of the aryl boronic acid pinacol ester precursor. Radiometabolite analysis was performed in mouse plasma samples 30 min p.i. The target specificity was investigated by in vitro autoradiographic studies with or without the sigma2 receptor antagonist ISO-1 in rat brain cryosections with a stereotactically implanted F98 glioma [3]. The biodistribution of [18F]RM273 in healthy mice (female, CD1; n = 4; 7.2 ± 1.1 MBq) and the tumour uptake into the F98 glioma (male, Fischer rats; n = 2; 21 and 25 MBq) were investigated by dynamic PET imaging for 60 min (nanoScan®PET-1T MRI, Mediso).
Polar radiometabolites of [18F]RM273 (AM 69 – 233 GBq/μmol, RCY 8%) were detectable in plasma, but not in brain extracts. We determined a 3-times higher density of binding sites in tumour compared to healthy brain in vitro [3]. PET studies revealed a TAC peak value of 1.3 at 2.25 min p.i. followed by a wash out in the brain of healthy mice [3]. In the F98 glioma brain region a two times higher uptake (SUVmean of 0.8–1.3 at 30–60 min p.i.) compared to contralateral was observable. Therefore, [18F]RM273 could potentially be used to determine the proliferative status of brain tumours.
Acknowledgements: This work was supported by the Deutsche Forschungsgemeinschaft (DFG: BR 1360/13-1).
References: [1] Shoghi et al. Plos One 2013, 8: e74188; [2] Yang et al. Molecules 2020, 25 (22): 5439 [3] Moldovan et al. Int. J. Mol. Sci. 2021, 22: 5447

Keywords: Sigma 2 recceptor; glioma; PET; [18F]RM273

  • Poster
    PET iS Wonderful, 23.-24.10.2023, Edinburgh, Scotland
  • Lecture (Conference)
    PET Is Wonderful, 23.-24.10.2023, Edinburgh, Scotland

Permalink: https://www.hzdr.de/publications/Publ-37418
Publ.-Id: 37418


Development of a Highly Specific 18F-labeled Radioligand for Imaging of Sigma-2 Receptor in Brain Tumor

Wang, T.; Wang, J.; Chen, L.; Zhang, X.; Mou, T.; An, X.; Zhang, J.; Zhang, X.; Deuther-Conrad, W.; Huang, Y.; Jia, H.

Series of novel ligands with the 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline or 5,6-dimethoxyisoindoline pharmacophore were designed and synthesized for evaluation of their structure-activity relationship to the sigma-2 (2) receptor and development as suitable PET radioligands. Compound 1 was found to possess nanomolar affinity (6.97 nM) for the 2 receptor, high subtype selectivity (58-fold) and high selectivity over 40 other receptors and transporters. Radioligand [18F]1 was prepared with radiochemical yield of 37–54%, > 99% radiochemical purity, molar activity of 107–189 GBq/μmol. Biodistribution and blocking studies in mice and micro-PET/CT imaging of [18F]1 in rats indicated excellent binding specificity of [18F]1 to the 2 receptors in vivo. Micro-PET/CT imaging of [18F]1 in the U87MG glioma xenograft model demonstrated clear tumor visualization with high tumor uptake and tumor-to-background ratio. Co-injection with CM398 (5 mol/kg) led to remarkable reduction of tumor uptake (80%, 60–70 min), indicating high specific binding of [18F]1 in U87MG glioma xenografts.

Keywords: 2 receptor; benzimidazolone derivative; brain tumor; positron emission tomography; fluorine-18

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  • Secondary publication expected from 13.09.2024

Permalink: https://www.hzdr.de/publications/Publ-37417
Publ.-Id: 37417


Acoustically induced spin resonances of silicon-vacancy centers in 4H-SiC

Vasselon, T.; Hernandez-Mınguez, A.; Hollenbach, M.; Astakhov, G.; Santos, P. V.

The long-lived and optically addressable spin states of silicon vacancies (VSi) in 4H-SiC make them promising qubits for quantum communication and sensing. These color centers can be created in both the hexagonal (V1) and in the cubic (V2) local crystallographic environments of the 4H-SiC host. While the spin of the V2 center can be efficiently manipulated by optically detected magnetic resonance at room temperature, spin control of the V1 centers above cryogenic temperatures has been elusive. Here, we show that the dynamic strain of surface acoustic waves can overcome this limitation and efficiently excite magnetic resonances of V1 centers up to room temperature. Based on the width and temperature dependence of the acoustically induced spin resonances, we attribute them to transitions between spin sublevels in the excited state. The acoustic spin control of both V1 and V2 centers in their excited states opens new ways for applications in quantum technologies based on spin-optomechanics.

Keywords: Quantum technologies; Acoustic; Spintronics; Defects; Silicon carbide

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Permalink: https://www.hzdr.de/publications/Publ-37416
Publ.-Id: 37416


Dataset on European Project ENTENTE Deliverable D4.5 "Hybrid hardening models from SANS and nanoindentation experiments

Bergner, F.; Altstadt, E.; Brandenburg, J.-E.; Chekhonin, P.; Ulbricht, A.

This dataset covers experimental data obtained for neutron-irradiated reactor pressure vessel (RPV) steels, in detail type and composition of steels, initial microstructure, initial properties, irradiation conditions, irradiation-induced microstructure changes and irradiation-induced property changes. The metadata sections of the data compilation include references to published journal articles and reports, where the data were originally published. A special feature of the data compilation is the availability of the characteristics of irradiation-induced nm-sized solute atom clusters derived from small-angle neutron scattering (SANS) experiments for each of the RPV materials and irradiation conditions considered. These characteristics, including cluster volume fraction and size, are statistically reliable and macroscopically representative. Moreover, results of Vickers hardness tests obtained using the same samples and also probing macroscopic volumes are provided. The data compilation is organized in the format of an Excel workbook called SANS-RPV. There are numerous potential applications of the data compilation such as the comparison of cluster characteristics derived from SANS and APT experiments, the correlation between cluster volume fraction and irradiation-induced hardness increase or brittle-ductile transition temperature shift, microstructure-informed predictions of the initial yield stress or irradiation-induced yield stress increase or the assessment of embrittlement trend curce (ETC) models, to mention a few. As an illustration, selected applications are saved in a separate Excel file called SANS_RPV_Analyses, which is included in the dataset. The background and usage of the data compilation as well as applications and implications are part of a study performed within the European Project ENTENTE. A copy of the project report draft (Deliverable D4.5) is included in the dataset.

Keywords: Reactor pressure vessel steels; Neutron irradiation; Microstructure; Mechanical properties; Hardening; Embrittlement; Small-angle neutron scattering

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Permalink: https://www.hzdr.de/publications/Publ-37415
Publ.-Id: 37415


Numerical Simulation of Particles in Rising Gas Bubbles

Mathew, A. T.; Maestri, R.; Lecrivain, G.

Numerical Simulation of Particles in Rising Gas Bubbles

Keywords: Taylor bubble; Simulation; Computational Fluid Dynamics

  • Study thesis
    TUBAF, 2023
    Mentor: Maestri, Rhandrey; Lecrivain, Gregory

Permalink: https://www.hzdr.de/publications/Publ-37414
Publ.-Id: 37414


Curvilinear and 3D micromagnetism: geometrically curved ferro- and antiferromagnets

Makarov, D.

Curvilinear magnetism is a framework, which helps understanding the impact of geometrical curvature on complex magnetic responses of curved 1D wires and 2D shells [1-3]. The lack of inversion symmetry and emergence of curvature induced anisotropy and Dzyaloshinskii-Moriya interaction (DMI) stemming from the exchange interaction [4,5] are characteristic of curved surfaces. Recently, a non-local chiral symmetry breaking was discovered [6], which is responsible for the coexistence and coupling of multiple magnetochiral properties within the same magnetic object [7].
Regarding antiferromagnets, it is demonstrated that intrinsically achiral one-dimensional curvilinear antiferromagnets behave as a chiral helimagnet with geometrically tunable DMI, orientation of the Neel vector and the helimagnetic phase transition [8-10]. This positions curvilinear antiferromagnets as a platform for geometrically tunable antiferromagnetic spinorbitronics.

[1] D. Makarov et al., Curvilinear micromagnetism: from fundamentals to applications (Springer, Zurich, 2022).
[2] D. Makarov et al., Adv. Mat. 34, 2101758 (2022).
[3] D. Sheka et al., Small 18, 2105219 (2022).
[4] Y. Gaididei et al., PRL 112, 257203 (2014).
[5] O. Volkov et al., PRL 123, 077201 (2019).
[6] D. Sheka et al., Commun. Phys. 3, 128 (2020).
[7] O. Volkov et al., Nature Com. 14, 1491 (2023).
[8] O. Pylypovskyi et al., Nano Lett. 20, 8157 (2020).
[9] O. Pylypovskyi et al., APL 118, 182405 (2021).
[10] Y. Borysenko et al., PRB 106, 174426 (2022).

Keywords: curvilinear magnetism; 3D nanostructures

Related publications

  • Invited lecture (Conferences)
    68th Annual Conference on Magnetism and Magnetic Materials, 30.10.-03.11.2023, Dallas, USA

Permalink: https://www.hzdr.de/publications/Publ-37413
Publ.-Id: 37413


Curvilinear and 3D low-dimensional magnetic architectures in research and technology

Makarov, D.

Extending 2D structures into 3D space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics, superconductivity and magnetism [1,2]. This approach provides means to modify conventional or to launch novel functionalities by tailoring curvature and 3D shape of magnetic thin films and nanowires [2,3]. In this talk, we will address fundamentals of curvature-induced effects in magnetism and review current application scenarios. In particular, we will demonstrate that curvature allows tailoring fundamental anisotropic and chiral magnetic interactions [4] and enables fundamentally new non-local chiral symmetry breaking effect [5,6]. Application potential of geometrically curved magnetic architectures is currently being explored as mechanically reshapeable magnetic field sensors for automotive applications, memory, spin-wave filters, high-speed racetrack memory devices, magnetic soft robotics [7] as well as on-skin interactive electronics relying on thin films [8,9,10] as well as printed magnetic composites [11,12,13].

[1] P. Gentile et al., Electronic materials with nanoscale curved geometries. Nature Electronics (Review) 5, 551 (2022).
[2] D. Makarov et al., New Dimension in Magnetism and Superconductivity: 3D and Curvilinear Nanoarchitectures. Advanced Materials (Review) 34, 2101758 (2022).
[3] D. Makarov et al., Curvilinear micromagnetism: from fundamentals to applications (Springer, Zurich, 2022).
[4] O. Volkov et al., Experimental observation of exchange-driven chiral effects in curvilinear magnetism. Physical Review Letters 123, 077201 (2019).
[5] D. D. Sheka et al., Nonlocal chiral symmetry breaking in curvilinear magnetic shells. Communications Physics 3, 128 (2020).
[6] O. M. Volkov et al., Chirality coupling in topological magnetic textures with multiple magnetochiral parameters. Nature Communications 14, 1491 (2023).
[7] M. Ha et al., Reconfigurable Magnetic Origami Actuators with On-Board Sensing for Guided Assembly. Advanced Materials 33, 2008751 (2021).
[8] G. S. Canon Bermudez et al., Magnetosensitive e-skins for interactive devices. Advanced Functional Materials (Review) 31, 2007788 (2021).
[9] J. Ge et al., A bimodal soft electronic skin for tactile and touchless interaction in real time. Nature Communications 10, 4405 (2019).
[10] G. S. Canon Bermudez et al., Electronic-skin compasses for geomagnetic field driven artificial magnetoception and interactive electronics. Nature Electronics 1, 589 (2018).
[11] M. Ha et al., Printable and Stretchable Giant Magnetoresistive Sensors for Highly Compliant and Skin-Conformal Electronics. Advanced Materials 33, 2005521 (2021).
[12] 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).
[13] R. Xu et al., Self-healable printed magnetic field sensors using alternating magnetic fields. Nature Communications 13, 6587 (2022).

Keywords: curvilinear magnetism; magnetic solitons; printed magnetoelectronics; shapeable magnetic field sensors

Related publications

  • Invited lecture (Conferences)
    XII-Latin American Workshop on Magnetism, Magnetic Materials & their Applications, 16.-20.10.2023, Puerto Varas, Chile

Permalink: https://www.hzdr.de/publications/Publ-37412
Publ.-Id: 37412


From curvilinear magnetism to shapeable magnetoelectronics

Makarov, D.

Extending 2D structures into 3D space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics, superconductivity and magnetism [1,2]. This approach provides means to modify conventional or to launch novel functionalities by tailoring curvature and 3D shape of magnetic thin films and nanowires [2,3]. In this talk, we will address fundamentals of curvature-induced effects in magnetism and review current application scenarios. In particular, we will demonstrate that curvature allows tailoring fundamental anisotropic and chiral magnetic interactions [4] and enables fundamentally new non-local chiral symmetry breaking effect [5,6]. Application potential of geometrically curved magnetic architectures is currently being explored as mechanically reshapeable magnetic field sensors for automotive applications, memory, spin-wave filters, high-speed racetrack memory devices as well as on-skin interactive electronics relying on thin films [7,8] as well as printed magnetic composites [9] with appealing self-healing performance [10].

Reference list
[1] P. Gentile et al., Electronic materials with nanoscale curved geometries. Nature Electronics (Review) 5, 551 (2022).
[2] D. Makarov et al., New Dimension in Magnetism and Superconductivity: 3D and Curvilinear Nanoarchitectures. Advanced Materials (Review) 34, 2101758 (2022).
[3] D. Makarov et al., Curvilinear micromagnetism: from fundamentals to applications (Springer, Zurich, 2022).
[4] O. Volkov et al., Experimental observation of exchange-driven chiral effects in curvilinear magnetism. Physical Review Letters 123, 077201 (2019).
[5] D. D. Sheka et al., Nonlocal chiral symmetry breaking in curvilinear magnetic shells. Communications Physics 3, 128 (2020).
[6] O. M. Volkov et al., Chirality coupling in topological magnetic textures with multiple magnetochiral parameters. Nature Communications 14, 1491 (2023).
[7] J. Ge et al., A bimodal soft electronic skin for tactile and touchless interaction in real time. Nature Communications 10, 4405 (2019).
[8] G. S. Canon Bermudez et al., Electronic-skin compasses for geomagnetic field driven artificial magnetoception and interactive electronics. Nature Electronics 1, 589 (2018).
[9] M. Ha et al., Printable and Stretchable Giant Magnetoresistive Sensors for Highly Compliant and Skin-Conformal Electronics. Advanced Materials 33, 2005521 (2021).
[10] R. Xu et al., Self-healable printed magnetic field sensors using alternating magnetic fields. Nature Communications 13, 6587 (2022).

Keywords: curvilinear magnetism; shapeable magnetoelectronics; printed magnetoelectronics; soft magnetic composites

Related publications

  • Invited lecture (Conferences) (Online presentation)
    NATO advanced research workshop "Functional Spintronic Nanomaterials 
for Radiation Detection and Energy Harvesting", 25.-27.09.2023, Kyiv, Ukraine

Permalink: https://www.hzdr.de/publications/Publ-37411
Publ.-Id: 37411


Development of Zinc Targetry: Production of diagnostic 67Ga and theranostic 67Cu

Brühlmann, S. A.; Walther, M.; Kreller, M.; Reissig, F.; Pietzsch, H.-J.; Knieß, T.; Kopka, K.

Objectives: Radionuclide availability plays a key role for development of new radiopharmaceuticals. Moreover, theranostic matched pairs of radionuclides have aroused interest in the last couple of years. On the one hand, 68Ga has been used as a diagnostic counterpart to the therapeutic β--emitter 177Lu, however, due to its short half-life (68 min), further alternatives have to be considered. In particular 67Ga (half-life: 3.26 d) as the longest-lived of the radiogallium isotopes has γ-lines that can be used for SPECT imaging (93.3 keV, 184 keV). On the other hand, 67Cu is referred as a theranostic radionuclide due to its β--emission and γ-emission suitable for SPECT, forming a perfect matched pair with the PET radionuclides 61/64Cu. At HZDR the zinc targetry and target chemistry developed for 67Cu production [1] has been applied to produce 67Ga.

Methods: 67Cu production consisted of proton irradiation (16.8 MeV, 60 µA, up to 20 h, 30° solid target configuration) of 70Zn targets (100-140 mg/cm2) electrodeposited onto silver via the 70Zn(p,α)67Cu nuclear reaction. Target work-up comprise a two- or three-step chromatographic column separation [1]. Gamma spectroscopy was used to quantify the radionuclidic purity (RNP), ICP-MS for the molar activity (Am) and test radiolabeling with the macrocyclic complexing agent TETA for apparent molar activity (AMA) quantification. Additionally, 67Ga was produced by proton irradiation (19 MeV, 35 µA, 2 h, 30° solid target configuration) of enriched 68Zn targets (60-70 mg/cm2) electrodeposited onto gold via the 68Zn(p,2n)67Ga nuclear reaction. After “cooling down” of the target (12-16 h, decay of co-produced 68Ga), the radiochemical separation consisted of a two-step chromatographic column separation; first a 1 mL TK400 cartridge followed by a 0.3 mL DGA branched cartridge. RNP was quantified by gamma spectroscopy.

Results: Activity yields of > 1.0 GBq 67Cu at EOB were reached, leading to over 800 MBq [67Cu]CuCl2 at EOP in 1.5 mL of 0.05 M HCl with RNP g.t. 99.5 % (at EOP) and AMA up to 300 GBq/µmol (EOB corrected). Furthermore, activities of up to 1.8 GBq 67Ga at EOB, and ca. 1.0 GBq [67Ga]GaCl3 at EOP in 0.5 mL of 0.05 M HCl were produced. First 67Ga gamma spectroscopy results showed a RNP of over 99 % at EOP. In both cases, the activity reached represented about 60 % to 70 % of the calculated yield.

Conclusions: Production of the radionuclides 67Cu and 67Ga from proton irradiation of zinc targets is being performed at HZDR. Both radionuclide product solutions proved sufficient quality regarding RNP and radiolabeling properties. further optimization of the 67Ga production is planned. Although 67Cu activities produced are not enough for clinical demand, the obtained yields are adequate for first in vitro and in vivo studies while other production routes are being explored.

References:

[1] Brühlmann SA, Walther M, Kreller M, Reissig F, Pietzsch H-J, Knieß T and Kopka K. Pharmaceuticals 2023, 16, 314.

  • Contribution to proceedings
    29. Jahrestagung der AGRR, 28.-30.09.2023, Bad Salzuflen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37410
Publ.-Id: 37410


Production of Lanthanum-133 via the134Ba(p,2n)133La Nuclear Reaction with High Radionuclide Purity for Theranostic Purposes

Brühlmann, S. A.; Kreller, M.; Pietzsch, H.-J.; Kopka, K.; Mamat, C.; Walther, M.; Reissig, F.

Aim/Introduction: Actinium-225 has gained great importance in Targeted Alpha Therapy (TAT) due to its suitable physical and chemical properties. In past years, studies using 225Ac-PSMA-617 have shown promising results [1], however, the macropa chelator has proven more beneficial properties regarding labelling and stability in vivo as compared with DOTA. While 68Ga has been used for DOTA-based radioconjugates, the macropa chelator lacks an imaging radionuclide counterpart. For this purpose, the β+-emitter 133La is an attractive candidate due to its physical properties and similar to 225Ac coordination chemistry. Following our recent publication [2], further optimization of the production of 133La with high radionuclidic purity (RNP) for theranostic purposes is presented. Materials and Methods: Lanthanum-133 was produced via the 134Ba(p,2n)133La nuclear reaction. Proton irradiation (19 MeV, 35 µA, 30 min) was performed using the HZDR TR-FLEX (ACSI) cyclotron on silver discs filled with 25 mg of [134Ba]BaCO3 capped with a 25 µm aluminum foil. The solid target was opened and the powder dissolved in 2 mL of 1 M HNO3. A one-step separation was carried out with a branched DGA resin cartridge after testing other resins. The 134Ba-containing fractions were collected and recycled through [134Ba]BaCO3 precipitation. Test radiolabelling of macropa-derived PSMA conjugates previously published by our group was performed in the MBq/nmol range [3]. Results: Lanthanum-133 yields of ca. 1.8 GBq for the described targets were reached at end of bombardment (EOB), accounting for about 65 % of the theoretical yield. After radiochemical separation, 1.2 GBq 133La were collected in 1 mL of 0.05 M HCl ready to label, with a RNP over 99.5 %. Further studies showed no detriment of the RNP by 21 MeV proton irradiation, thus being feasible irradiation of larger targets (prior thermal studies). Furthermore, quantitative radiolabeling was achieved with ligand concentrations down to 300 MBq/nmol. Conclusion: Lanthanum-133 of high RNP was produced for the first time. Considering future medical demands, the scale up to radioactivity amounts that are needed for clinical application purposes could be achieved by increasing the irradiation time. Alternatively, irradiation with higher currents or of thicker targets could also lead to higher activities. Based on these results, our group will attempt to establish a diagnostic platform for 225Ac-TAT based on 133La-macropa radioconjugates instead of the conventional 68Ga-DOTA application. References: [1] Kratochwil et al., J. Nucl. Med. 2016, 57, 1941-1944 [2] Brühlmann et al., Pharmaceuticals 2022, 15, 1167. [3] Reissig et al., Cancers 2021, 13, 1974.

  • Open Access Logo Contribution to proceedings
    EANM'23, 09.-13.09.2023, Wien, Austria

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Publ.-Id: 37409


Data publication: Multitask learning with convolutional neural networks and vision transformers can improve outcome prediction for head and neck cancer patients

Starke, S.; Zwanenburg, A.; Leger, K.; Lohaus, F.; Linge, A.; Schreiber, A.; Kalinauskaite, G.; Tinhofer, I.; Guberina, N.; Guberina, M.; Balermpas, P.; von der Grün, J.; Ganswindt, U.; Belka, C.; Peeken, J. C.; Combs, S. E.; Böke, S.; Zips, D.; Richter, C.; Troost, E. G. C.; Krause, M.; Baumann, M.; Löck, S.

This dataset contains the model checkpoints, predictions and performance metrics for the multitask neural networks presented in the corresponding manuscript.

Keywords: survival analysis; vision transformer; convolutional neural network; multitask learning; tumor segmentation; head and neck cancer; Cox proportional hazards; loco-regional control; progression-free survival; discrete-time survival models

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Publ.-Id: 37408


Cyclotron-based production of the theranostic radionuclide 67Cu

Brühlmann, S. A.; Walther, M.; Kreller, M.; Reissig, F.; Pietzsch, H.-J.; Knieß, T.; Kopka, K.

Objectives
Copper-67 (half-life 61.83 h, β--emission [mean energy 140 keV], γ-emission [184.6 keV, 48.7 % intensity]), is a promising radiometal due to its theranostic potential. Moreover, it forms a perfect matched pair with the
β+-emitters 61Cu and 64Cu. However, broad application of this radionuclide is limited due to its low availability. In this work, we investigate the no-carrier-added 67Cu production via the 70Zn(p,α)67Cu reaction [1].

  • Contribution to proceedings
    10. Radiochemischer Workshop, 12.-14.06.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37407
Publ.-Id: 37407


Understanding electronic correlations in warm dense quantum plasmas

Dornheim, T.

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. This includes recent results for various density response properties [3] such as the exchange—correlation (XC) kernel [2,4], and the utility of PIMC reference data to assess the accuracy of different XC functionals [5].

Finally, 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 [6] 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 [7]. As an outlook, I will show how new PIMC capabilities [8] will allow to give us novel insights into electronic correlations in warm dense quantum plasmas, leading to unprecedented agreement between experiments [9] 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] T. Dornheim et al., Physics of Plasmas 30, 032705 (2023)
[4] Zh. Moldabekov et al., Journal of Chemical Theory and Computation 19, 1286-1299 (2023)
[5] Zh. Moldabekov et al., arXiv:2308.07916 (submitted)
[6] T. Dornheim et al., Nature Communications 13, 7911 (2022)
[7] T. Dornheim et al., arXiv:2305.15305 (submitted)
[8] T. Dornheim et al., arXiv:2308.06071 (submitted)
[9] T. Döppner et al., Nature 618, 270-275 (2023)

  • Invited lecture (Conferences)
    CECAM Flagship Workshop: Accelerating Improvements in Density Functional Theory, 21.-25.08.2023, Lausanne, Schweiz

Permalink: https://www.hzdr.de/publications/Publ-37406
Publ.-Id: 37406


Cyclotron-based Production of Lanthanum-133 with High Radionuclide Purity for Theranostic Purposes

Brühlmann, S. A.; Kreller, M.; Pietzsch, H.-J.; Kopka, K.; Mamat, C.; Walther, M.; Reissig, F.

Objectives:

Targeted Alpha Therapy (TAT) is a research field of highest interest in specialized molecular radionuclide therapy. In particular, the radionuclide actinium-225 provides all necessary physical and chemical properties for a successful clinical application. Although the macropa chelator has shown beneficial properties regarding labelling and stability in vivo as compared with DOTA, the former lacks an imaging radionuclide counterpart to 225Ac. In this connection, lanthanum is an appropriate surrogate for actinium due to its comparable coordination chemistry. Furthermore, the imaging properties of the β+-emitter lanthanum-133 makes it an attractive candidate as a theranostic matched pair to 225Ac. Following our recent publication [1], 133La of high radionuclide purity for theranostic purposes was produced through the 134Ba(p,2n)133La reaction.

  • Open Access Logo Contribution to proceedings
    25th International Symposium in Radiopharmaceutical Sciences, 22.-26.05.2023, Honolulu, USA

Permalink: https://www.hzdr.de/publications/Publ-37405
Publ.-Id: 37405


Cyclotron Production of Copper-67: Exploring the limits

Brühlmann, S. A.; Walther, M.; Kreller, M.; Reissig, F.; Pietzsch, H.-J.; Knieß, T.; Kopka, K.

Objectives.
Copper-67 (67Cu, half-life 61.83 h, β--emission [mean energy 140 keV], γ-emission [184.6 keV with 48.7 % intensity, i.a.]), is a promising radiometal due to its theranostic potential. While 61Cu and 64Cu are suitable for PET, matched pair 67Cu brings a therapeutic counterpart to the table. However, broad application of this radionuclide is limited due to its low availability. No-carrier-added 67Cu can be produced through the 70Zn(p,α)67Cu reaction, while featuring a low yield and the need of expensive 70Zn target material. Nevertheless, co-production of other copper nuclides (from other zinc isotopes low-content) as well as contamination with stable copper can be minimized but not completely eliminated.

  • Open Access Logo Contribution to proceedings
    25th International Symposium in Radiopharmaceutical Sciences, 22.-26.05.2023, Honolulu, USA

Permalink: https://www.hzdr.de/publications/Publ-37404
Publ.-Id: 37404


Guidance for measuring the axial gas dispersion coefficient in bubble columns via gas flow modulation

Marchini, S.; Bieberle, A.; Schubert, M.; Hampel, U.

The gas flow modulation technique (GFM) is a novel non-invasive approach for measuring the axial gas dispersion coefficient in bubble columns. The approach overcomes the limitations of traditional tracer-based techniques, qualifying it as a promising candidate for measurements in an industrial setting. The current work elaborates systematic guidelines for selecting the experimental parameters for the GFM. These guidelines are crucial for its successful application. In addition, a novel approach is proposed for confidently extracting the values and the uncertainty limits of the axial gas dispersion coefficient. Afterwards, we show the application of these guidelines in the frame of a case study that serves the purpose to illustrate their application and to demonstrate their usefulness.

Keywords: gas flow modulation; axial dispersion coefficient; bubble columns; gas flow modulation workflow

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Permalink: https://www.hzdr.de/publications/Publ-37403
Publ.-Id: 37403


Unravelling the nonlinear ideal density response of many-body systems

Tolias, P.; Dornheim, T.; Moldabekov, Z.; Vorberger, J.

Nonlinear density response theory is revisited focusing on the harmonically perturbed finite temperature uniform electron gas. Within the non-interacting limit, brute force quantum kinetic theory calculations for the quadratic, cubic, quartic and quintic responses reveal a deep connection with the linear response. Careful analysis of the static long wavelength limit led us to conjecture a canonical non-interacting form that expresses arbitrary order nonlinear responses as the weighted sum of the linear responses evaluated at all multiple harmonics. This harmonic expansion is successfully validated against ab initio path integral Monte Carlo simulations.

Permalink: https://www.hzdr.de/publications/Publ-37402
Publ.-Id: 37402


Schätze im Müll

Matys, S.

Anhand des Beispiels Mobiltelefon wird erklärt, wie viele wertvolle Rohstoffe in elektronischen Geräten stecken und wie die Forschenden am HIF mit der Etablierung neuer (bio)technologischer Methoden dazu beitragen, dem Ziel einer geschlossenen Kreislaufwirtschaft näher zu kommen.

Keywords: Biotechnologie; Kreislaufwirtschaft; Wertstoffe; Metalle

  • Lecture (others)
    Abschlussveranstaltung Mathematikolympiade 2023 Landkreis Bautzen, 26.02.2023, Radeberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37401
Publ.-Id: 37401


Asphericity derived from [18F]FDG PET as a new prognostic parameter in cervical cancer patients

Cegla, P.; Hofheinz, F.; Burchardt, E.; Czepczyński, R.; Kubiak, A.; van den Hoff, J.; Nikulin, P.; Bos-Liedke, A.; Roszak, A.; Cholewinski, W.

The objective of this study was to assess the prognostic value of asphericity (ASP) and standardized uptake ratio (SUR) in cervical cancer patients. Retrospective analysis was performed on a group of 508 (aged 55 ± 12 years) previously untreated cervical cancer patients. All patients underwent a pretreatment [18F]FDG PET/CT study to assess the severity of the disease. The metabolic tumor volume (MTV) of the cervical cancer was delineated with an adaptive threshold method. For the resulting ROIs the maximum standardized uptake value (SUVmax) was measured. In addition, ASP and SUR were determined as previously described. Univariate Cox regression and Kaplan–Meier analysis with respect to event free survival (EFS), overall survival (OS), freedom from distant metastasis (FFDM) and locoregional control (LRC) was performed. Additionally, a multivariate Cox regression including clinically relevant parameters was performed. In the survival analysis, MTV and ASP were shown to be prognostic factors for all investigated endpoints. Tumor metabolism quantified with the SUVmax was not prognostic for any of the endpoints (p > 0.2). The SUR did not reach statistical significance either (p = 0.1, 0.25, 0.066, 0.053, respectively). In the multivariate analysis, the ASP remained a significant factor for EFS and LRC, while MTV was a significant factor for FFDM, indicating their independent prognostic value for the respective endpoints. The alternative parameter ASP has the potential to improve the prognostic value of [18F]FDG PET/CT for event-free survival and locoregional control in radically treated cervical cancer patients.

Keywords: NA

Permalink: https://www.hzdr.de/publications/Publ-37400
Publ.-Id: 37400


Multi-sensor spectral database of WEEE polymers

de Lima Ribeiro, A.; Fuchs, M.; Lorenz, S.; Röder, C.; Heitmann, J.; Gloaguen, R.
DataCollector: Madriz, Yuleika; DataCollector: Herrmann, Erik

Polymers represent around 25% of total waste from electronic and electric equipment. Any successful recycling process must ensure that polymer-specific functionalities are preserved, to avoid downcycling. This requires a precise characterization of particle compounds moving at high speeds on conveyor belts in processing plants. We present a multi-sensor database including spectra acquired from imaging and point measurement sensors on 23 polymers including ABS, PS, PC, PE-types, PP, PVC, PET-types, PMMA, and PTFE. The techniques applied include hyperspectral imaging sensors (HSI) to map reflectance in the visible to near infrared (VNIR, (350–1000) nm ), short-wave (SWIR, (1000–2500) nm) and mid-wave infrared (MWIR, (2500–5000) nm) as well as point Raman, FTIR and portable spectral spectroradiometer (PSR) instruments.

Keywords: plastics; e-waste; hyperspectral; Raman

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Permalink: https://www.hzdr.de/publications/Publ-37399
Publ.-Id: 37399


Coupled 3D neutronics/thermal-hydraulics analysis of Superphénix start-up tests with DYN3D/ATHLET code system

Ponomarev, A.; Nikitin, E.; Fridman, E.

The capabilities of the DYN3D/ATHLET coupled code system were recently extended to allow for 3D neutron kinetics/thermal hydraulics analyses of Sodium cooled Fast Reactors at reactor system level. In this paper, the DYN3D/ATHLET coupled code system was applied to analyze the Superphenix reactor transient benchmark. The benchmark comprises six operational transients initiated during the SPX reactor start-up tests, covering a wide range of reactor operating states. The peculiarity of these transients is the necessity to consider thermal expansions of major structural elements of the primary system, which significantly influence the transient position of control rods in the core. The paper includes a brief summary of the benchmark specifications, description of the neutron kinetics and thermal hydraulics models, an analysis of the simulation results, and a comparison to the experimental data.

Keywords: ATHLET; DYN3D; Monte Carlo; Serpent; SFR; Superphenix; Thermal hydraulics analysis; Control rods

Permalink: https://www.hzdr.de/publications/Publ-37397
Publ.-Id: 37397


Strömungstechnischer Funktionsnachweis für Verschlussbauwerke und flüssigkeitsgestützte Abdichtung des Kontaktbereiches Phase III (Vertiefung Kenntnisstand Kontaktbereich & Injektionsmittel, in situ-Versuche) (STROEFUN III) Schlussbericht (Hauptband)

Bauermeister, J.; Langefeld, O.; Schieweg, A.; Raebiger, L.; Abel, P.; Viertel, T.; Flemming, J.; Noorhan, W.; Ley, S.; Glaubach, U.; Wilsnack, T.; Müller-Hoeppe, N.; Hussein, A.; Fischer, T.; Lack, D.; Schicht, T.; Brüning, M.; Kulenkampff, J.

In dem Forschungsvorhaben STROEFUN III wurde ein Konzept für die strömungstechnische Testung von Streckenverschlussbauwerken entwickelt, installiert und in einem Streckenver-schlussbauwerk in der Grube Teutschenthal erfolgreich getestet. Das Testkonzept für Bauwerke oder Bauwerksabschnitte aus hydraulisch abbindenden Dichtbaustoffen basiert auf der Druckbeaufschlagung von mindestens 3 an der Streckenkontur installierten Ringkammern. Diese können individuell mit Gas und/oder Flüssigkeit im stationären oder instationären Druck-regime beaufschlagt werden. Das Konzept konzentriert sich auf die Testung des Kontaktbereiches Baustoff/ Gebirge als bestimmenden Strömungsraum für die Dichtwirkung von Stre-ckenverschlussbauwerken. Im Ergebnis der modellbasierten Auswertung der im Test ermittelten Druckganglinien sind Aussagen über die Permeabilität des Bauwerkes im Kontakt Bau-stoff/ Gebirge und, daraus abgeleitet, für die integrale Permeabilität des Bauwerkes möglich. Das Testkonzept ist ein zusätzlicher Baustein für den gegenständlichen, strömungstechni-schen Funktionstest von Streckenverschlussbauwerken im Rahmen der Nachweisführung. Im Ergebnis des Forschungsvorhabens liegen umfangreiche Kenntnisse zum Standort und zum Bauwerk aus MgO-Baustoff (angelehnt an die A1-Basisrezeptur) vor. Dieser umfangreiche Kenntnisstand, die Zugänglichkeit und die Standortbedingungen bieten die Chance in der nahen Zukunft eine Vielzahl an Untersuchungen zur nachträglichen Vergütung des Bauwerkes mit Beurteilung der strömungstechnischen Wirkung der Vergütung sowie zum zeitabhängigen Baustoffverhalten im Kontakt zur Atmosphäre und im Kontakt zur Salzlösung durchzuführen.

In the research project STROEFUN III a concept for the fluidic testing of closuring structures was developed, installed and successfully tested on a closuring structure at the Teutschenthal mine. The test concept for structures or sections of structures made of hydraulically settling sealing materials is based on the pressurization of at least 3 ring chambers installed on the drift contour. These can be individually pressurized with gas and/or liquid in a steady-state or transient pressure regime. The concept concentrates on testing the contact area between material and rock mass as the determining flow space for the sealing effect of drift closure structures. As a result of the modelbased evaluation of the pressure hydrographs determined in the test, statements can be made about the permeability of the structure in the contact between the building material and the rock mass and, derived from this, about the integral permeability of the structure. The test concept is an additional option for the fluidic functional test of drifts closure structures within the scope of verification of sealing effect. As a result of the research project, extensive knowledge is available on the location and the structure made of MgO-building material. This extensive knowledge, the accessibility and the site conditions offer the opportunity in the near future to carry out a large number of investigations on the subsequent improvement of the structure with assessment of the fluidic effect of the improvement as well as on the time-dependent behavior of the building material in contact with the atmosphere and in contact with the salt solution.

Keywords: underground repository; underground dam sealing; MgO concrete; closure structure; µCT

Permalink: https://www.hzdr.de/publications/Publ-37396
Publ.-Id: 37396


Timing and origin of skarn-, greisen-, and vein-hosted tin mineralization at Geyer, Erzgebirge (Germany)

Meyer, N.; Markl, G.; Gerdes, A.; Gutzmer, J.; Burisch, M.

This contribution presents new insights into the origin and age relationships of the Geyer tin deposit in the Erzgebirge, Germany. Tin mineralization occurs in skarns, greisen, and in cassiterite-bearing fluorite-quartz veins. Skarn alteration replaces marble layers of the Cambrian Jáchymov Group and occurs in two clearly distinct stages. The first skarn stage forms skarnoid textured assemblages of clinopyroxene, garnet, and wollastonite with no tin phases recognized. Garnet U-Pb ages of this skarn stage (~322 Ma) relate the earlier skarn stage to the emplacement of the Ehrenfriedersdorf granite (~324 to 317 Ma). The second stage of skarn alteration is marked by the occurrence of malayaite and cassiterite associated with garnet recording ages of 307 to 301 Ma. Greisen- and skarn-hosted cassiterite-bearing veins provide U-Pb ages in the range of 308 to 305 Ma, relating greisenization and vein formation to the same magmatic-hydrothermal event as the second skarn stage. This suggests that tin mineralization at Geyer is related to a distinctly younger magmatic-hydrothermal event, clearly postdating the Ehrenfriedersdorf granite, which was previously assumed as the source of the tin-rich fluids. Fluid inclusions show salinities in the range of 1.0 to 31.5 % eq. w(NaCl±CaCl2) and homogenization temperatures between 255 and 340 °C. Cassiterite-associated fluid inclusions show indications for heterogeneous entrapment and dilution of hydrothermal with meteoric fluids. Dilution of high-salinity fluids with low-salinity fluids and cooling of the system was probably a decisive process in the precipitation of cassiterite in the Geyer Sn system.

Keywords: Erzgebirge; skarn; greisen; tin

Permalink: https://www.hzdr.de/publications/Publ-37395
Publ.-Id: 37395


Ion-induced telecom single-photon emitters in silicon

Astakhov, G.; Hollenbach, M.; Klingner, N.; Jagtap, N.; Bischoff, L.; Fowley, C.; Kentsch, U.; Hlawacek, G.; Erbe, A.; Abrosimov, N. V.; Helm, M.; Berencen, Y.

Single-photon emitters (SPEs) are one of the elementary building blocks for photonic quantum information and optical quantum computing. One of the upcoming challenges is the monolithic photonic integration and coupling of single-photon emission, reconfigurable photonic elements, and single-photon detection on a silicon chip in a controllable manner. Particularly, fully integrated SPEs on-demand are required for enabling a smart integration of advanced functionalities in on-chip quantum photonic circuits. The major challenge in realizing a fully monolithic, photonic integrated circuitry lies in the development of a quantum light source in silicon since the indirect nature of the small energy bandgap does not allow for efficient PL emission. Nevertheless, below-bandgap light emission can be used for good advantage by exploiting extrinsic and intrinsic point defects acting as SPEs. Indeed, the isolation of SPEs, such as G-, W-, and T-centers, in the optical telecommunication O-band has been recently realized in silicon.. In all these cases, however, SPEs were created uncontrollably in random locations, preventing their scalability.
We present mask-free nanofabrication involving a quasi-deterministic creation of single G- and W-centers in silicon wafers using focused-ion beam (FIB) writing. We also implement a scalable, broad-beam implantation protocol compatible with the complementary-metal-oxide-semiconductor (CMOS) technology to fabricate telecom SPEs at desired positions on the nanoscale.

Keywords: Quantum technologies; Single photon emitters; Silicon; Defects

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  • Invited lecture (Conferences)
    25th International Conference on the Electronic Properties of Two-Dimensional Systems (EP2DS-25) and 21st International Conference on Modulated Semiconductor Structures (MSS-21), 10.-14.07.2023, Grenoble, France

Permalink: https://www.hzdr.de/publications/Publ-37394
Publ.-Id: 37394


Hybrid quantum technologies with spin qubits in SiC

Astakhov, G.

An overview of quantum technologies based on spin defects in SiC is presented. It includes microwave assisted spectroscopy, inverted excited-state structure for spin-photon entanglement protocols and acoustic control of spin qubits.

Keywords: Quantum technologies; Spin qubits; Silicon carbide; Defects

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  • Invited lecture (Conferences)
    Seminar at the Institute of Applied Quantum Technologies, 09.02.2023, Erlangen, Germany

Permalink: https://www.hzdr.de/publications/Publ-37393
Publ.-Id: 37393


18F-FDG PET/CT-derived total lesion glycolysis predicts abscess formation in patients with surgically confirmed infective endocarditis: Results of a retrospective study at a tertiary center

Maria Sag, S. J.; Menhart, K.; Hitzenbichler, F.; Schmid, C.; Hofheinz, F.; van den Hoff, J.; Maier, L. S.; Hellwig, D.; Grosse, J.; Sag, C. M.

Background
Abnormal activity of 18F-FDG PET/CT is a major Duke criterion in the diagnostic work-up of infective prosthetic valve endocarditis (IE). We hypothesized that quantitative lesion assessment by 18F-FDG PET/CT-derived standard maximum uptake ratio (SURmax), metabolic volume (MV), and total lesion glycolysis (TLG) might be useful in distinct subgroups of IE patients (e.g. IE-related abscess formation).

Methods
All patients (n = 27) hospitalized in our tertiary IE referral medical center from January 2014 to October 2018 with preoperatively performed 18F-FDG PET/CT and surgically confirmed IE were included into this retrospective analysis.

Results
Patients with surgically confirmed abscess formation (n = 10) had significantly increased MV (by ~ fivefold) and TLG (by ~ sevenfold) as compared to patients without abscess (n = 17). Receiver operation characteristics (ROC) analyses demonstrated that TLG (calculated as MV × SURmean, i.e. TLG (SUR)) had the most favorable area under the ROC curve (0.841 [CI 0.659 to 1.000]) in predicting IE-related abscess formation. This resulted in a sensitivity of 80% and a specificity of 88% at a cut-off value of 14.14 mL for TLG (SUR).

Conclusion
We suggest that 18F-FDG PET/CT-derived quantitative assessment of TLG (SUR) may provide a novel diagnostic tool in predicting endocarditis-associated abscess formation.

Keywords: 18F-FDG PET/CT; infective endocarditis; total lesion glycolysis; valve abscess

Permalink: https://www.hzdr.de/publications/Publ-37392
Publ.-Id: 37392


Numerical Simulations of the Pore-Scale Flow in Ceramic Open-Cell Foams

Hernandez, J. N. C.; Schubert, M.; Hampel, U.

Porous materials are abundant in nature and in industrial applications. Their ability to allow fluids passing through them is of major importance and plays a very important role in various operations, such as hydrocarbon extraction of reservoirs in oil production [1]; or by dictating the amount of heat that can be dissipated from an electronic component using force convection (e.g. heat sinks) [2]. The key indicator of how easily fluids pass through porous materials is the “permeability”, which allows describing pressure loss and flow velocity in porous materials. However, the impact of droplet impingement inside open-cell foams and the retention time of a solid or liquid disperse phase cannot be described solely by the permeability. To study these phenomena current computing resources permit pore-scale CFD simulations, which relate structure and transport properties of porous materials. Instead of using equivalent geometrical models based on simple geometries just as spheres or cylinders, the genuine geometry representation of the porous structure is required, especially since porous media usually involve significant pore structure defects and feature multiple length scales, which produce different mechanisms of interaction within the pores.
The present work investigates the performance of pore-scale numerical simulations over genuine 3D geometrical representations of ceramic foams reconstructed from X-ray micro-computed tomography (μCT) scans of silicon-infiltrated silicon carbide” (SiSiC) open-cell foams with different nominal pore sizes using marching cubes algorithm [3]. To disclose the airflow velocity profile inside the foam simulations of single-phase air flow were conducted using finite volume method (FVM) for a wide range of Reynolds numbers including Reynolds-averaged Navier-Stokes (RANS) turbulence models. Good agreement was achieved especially between the computed pressure gradient and the experimental pressure measurements, even outperforming other conventional numerical models based on average pore properties such as porosity and surface area. Further simulations were carried out using a Lagrangian approach to analyze particular effects such as rebounding of a low mass fraction of the disperse phase on the ceramic structure and deposition thresholds.
The work already done pursues to improve upon the current state-of-the-art of pore-scale simulations, providing evidence of the feasibility to perform flow simulations on reconstructed representations of ceramic porous media that considerably are able to predict experimental flow properties.

  • Poster
    4th World Congress on Momentum, Heat and Mass Transfer (MHMT'19), 10.-12.04.2019, Rome, Italy
    DOI: 10.11159/icmfht19.124

Permalink: https://www.hzdr.de/publications/Publ-37391
Publ.-Id: 37391


Microwave Dielectric Properties of Open-Cell Solid Foams Based on Silicon Carbide Ceramics

Hernandez, J. N. C.; Sodatov, S.; Link, G.; Füssel, A.; Hampel, U.

Open-cell porous materials are abundant in industrial applications and are used for example as heat exchangers, thermal insulators, reaction catalysts, flow stabilizers, mass transfer enhancers, solar radiation absorbers and electrical heaters, etc. [1]. In recent years, the interest in solid foams based on silicon carbide “SiC” has regained popularity. Nevertheless, when applied to microwave applications there is a lack of reported properties. The key indicator of how a material interacts and is heated with microwaves is the “permittivity”, which is best described in a complex form. The aim of this work is to improve the database of complex permittivity of open-cell solid foams based on silicon carbide, which was determined using the cavity perturbation method [2]. Temperature dependent measurements of permittivity were performed in the range of 30 °C to 190 °C for three different foam materials, i.e. silicon infiltrated silicon carbide (SiSiC), pressureless sintered silicon carbide (SSiC) and silicate-bounded silicon carbide (SBSiC), with porosities in the range of 86.9 % to 96.5 % and pore size of 30 ppi (pore per inch), 45 ppi and 60 ppi. As a result, a model based on mixture rules was developed that well predicts the permittivity as a function of porosity.

Keywords: microwaves; complex permittivity; SiC; open-cell solid foams

  • Lecture (Conference)
    17th International Conference on Microwave and High Frequency Heating AMPERE 2019, 09.-12.6.2019, Valencia, Spain

Permalink: https://www.hzdr.de/publications/Publ-37390
Publ.-Id: 37390


Extending the coherence of spin defects in hBN enables advanced qubit control and quantum sensing

Rizzato, R.; Schalk, M.; Mohr, S.; Hermann, J. C.; Leibold, J. P.; Bruckmaier, F.; Salvitti, G.; Ji, P.; Astakhov, G.; Kentsch, U.; Helm, M.; Stier, A. V.; Finley, J. J.; Bucher, D. B.

Negatively-charged boron vacancy centers hexagonal Boron Nitride (hBN) are attracting increasing interest since they represent optically-addressable qubits in a van der Waals material. In particular, these spin defects have shown promise as sensors of temperature, pressure, and static magnetic fields. However, their short spin coherence time limits their scope for quantum technology. Here, we apply dynamical decoupling techniques to suppress magnetic noise and extend the spin coherence time by two orders of magnitude, approaching the fundamental T1 relaxation limit. Based on this improvement, we demonstrate advanced spin control and a set of quantum sensing protocols to detect electromagnetic signals in the MHz range with sub-Hz resolution. This work lays the foundation for nanoscale sensing using spin defects in an exfoliable material and opens a promising path to quantum sensors and quantum networks integrated into ultra-thin structures.

Keywords: Quantum technologies; 2D materials; Spintronics; Defects

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37389
Publ.-Id: 37389


Multitask Learning with Convolutional Neural Networks and Vision Transformers Can Improve Outcome Prediction for Head and Neck Cancer Patients

Starke, S.; Zwanenburg, A.; Leger, K.; Lohaus, F.; Linge, A.; Schreiber, A.; Kalinauskaite, G.; Tinhofer, I.; Guberina, N.; Guberina, M.; Balermpas, P.; von der Grün, J.; Ganswindt, U.; Belka, C.; Peeken, J. C.; Combs, S. E.; Böke, S.; Zips, D.; Richter, C.; Troost, E. G. C.; Krause, M.; Baumann, M.; Löck, S.

Neural-network-based outcome predictions may enable further treatment personalization of patients
with head and neck cancer. The development of neural networks can prove challenging when a limited number of cases is available. Therefore, we investigated whether multitask learning strategies, implemented through the simultaneous optimization of two distinct outcome objectives (multi-outcome) and combined with a tumor segmentation task, can lead to improved performance of convolutional neural networks (CNN) and vision transformers (ViT). Model training was conducted on two distinct multicenter datasets for the endpoints loco-regional control (LRC) and progression-free survival (PFS), respectively. The first dataset consisted of pre-treatment computed tomography (CT) imaging for 290 patients and the second dataset contained combined positron emission tomography (PET)/CT for 224 patients. Discriminative performance was assessed by the concordance index (C-index). Risk stratification was evaluated using log-rank tests. Across both datasets, CNN and ViT model ensembles achieved similar results. Multitask approaches showed favorable performance in most investigations. Multi-outcome CNN models trained with segmentation loss were identified as the optimal strategy across cohorts. On the PET/CT dataset, an ensemble of multi-outcome CNNs trained with segmentation loss achieved the best discrimination (C-index: 0.29, 95% confidence interval (CI): 0.22-0.36) and successfully stratified patients into groups with low and high risk of disease progression (p=0.003). On the CT dataset, ensembles of multi-outcome CNNs and of single-outcome ViTs trained with segmentation loss performed best (C-index: 0.26 and 0.26, CI: 0.18-0.34 and 0.18-0.35, respectively), both with significant risk stratification for LRC in independent validation (p=0.002 and p=0.011). Further validation of the developed multitask-learning models is planned based on a prospective validation study, which is currently ongoing.

Keywords: survival analysis; vision transformer; convolutional neural network; multitask learning; tumor segmentation; head and neck cancer; Cox proportional hazards; loco-regional control; progression-free survival; discrete-time survival models

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Permalink: https://www.hzdr.de/publications/Publ-37388
Publ.-Id: 37388


Plasmas, fluids and lasers

Nikl, J.

Plasma is the most abundant form of matter in our universe. Fluid dynamics then presents one of the most successful models of modern physics and lasers are the most versatile tools of the 21st century. All these topics are introduced and their joint applications at HZDR and elsewhere are presented.

  • Lecture (others)
    HZDR summer school, 31.07.-31.08.2023, HZDR Campus, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37387
Publ.-Id: 37387


Orientation resolved measurements of accelerations with sensor particles in bioreactors

Buntkiel, L.; Ma, Y.; Reinecke, S.; Hampel, U.

The measurement of the spatially distributed
flow field in large industrial vessels, e.g. biogas fermenters,
is not possible with commercially available measurement
equipment. Therefore the concept of flow following sensor
particles has been developed. They act as data loggers
within the vessel. The sensor particles are equipped with
a pressure sensor and an inertial measurement unit to
measure their motion. The measurements are taken in
the coordinate frame of the sensor particle and need to
be transformed into the vessel’s coordinate frame to ana-
lyze the flow field. This is done by an error-state Kalman
filter which estimates the orientation of the sensor par-
ticle with respect to the vessel based on the direction
of the gravitational acceleration and the local magnetic
field. Since no other aiding sensors are available or usable
within an industrial vessel particular emphasis was given
to the stochastic modeling of the inertial sensors and the
calibration of the accelerometer. Based on the orienta-
tion estimation, the measured acceleration is transformed
into the vessel frame. We performed two experiments in
a 1.4 m³ lab reactor to qualify this approach. The results
show, that the transformed acceleration is in good quali-
tative agreement with the known flow field inside the lab
reactor

Keywords: Sensor particle; Flow follower; Flow measurement; Kalman filter; Inertial measurements

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  • Secondary publication expected from 16.11.2024

Permalink: https://www.hzdr.de/publications/Publ-37386
Publ.-Id: 37386


Ultra-high dose rate radiobiology with protons at the DRACO and PENELOPE high power laser facilities

Metzkes-Ng, J.

Ultra-high dose rate radiobiology with protons at the DRACO and PENELOPE high power laser facilities

  • Invited lecture (Conferences)
    Very High Energy Electron Radiotherapy Conference 2023, 10.-13.07.2023, Hamburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37385
Publ.-Id: 37385


Fermionic physics from ab initio path integral Monte Carlo simulations of fictitious identical particles

Dornheim, T.; Tolias, P.; Groth, S.; Moldabekov, Z.; Vorberger, J.; Hirshberg, B.

The \emph{ab initio} path integral Monte Carlo (PIMC) method is one of the most successful methods in statistical physics, quantum chemistry and related fields, but its application to quantum degenerate Fermi systems is severely hampered by an exponential computational bottleneck: the notorious fermion sign problem. Very recently, Xiong and Xiong [J. Chem. Phys. 157, 094112 (2022)] have suggested to partially circumvent the sign problem by carrying out PIMC simulations of fictitious systems which contain an interpolating continuous variable ξ∈[−1,1] in their partition function, with the physical Fermi- and Bose-statistics corresponding to the endpoint limits ξ=−1 and ξ=1. It has been proposed that thermodynamic information about the fermionic limit might be obtained by path integral calculations within the bosonic sector ξ>0 combined with a quadratic ξ extrapolation throughout the fermionic sector ξ<0, essentially bypassing the sign problem. In this work, we show how the inclusion of the artificial parameter ξ can be interpreted as an effective penalty on the formation of permutation cycles in the PIMC simulation. We empirically demonstrate that the proposed extrapolation method breaks down for moderate to high quantum degeneracy. Instead, the method constitutes a valuable tool for the description of large Fermi-systems of weak quantum degeneracy. This is demonstrated for electrons in a 2D harmonic trap and for the archetypal uniform electron gas (UEG), where we find excellent agreement (∼0.5%) with exact configuration PIMC results in the high-density regime while attaining a speed-up exceeding eleven orders of magnitude. Finally, we extend the idea beyond the energy and analyze the radial density distribution (2D trap), as well as the static structure factor and imaginary-time density-density correlation function (UEG).

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37382
Publ.-Id: 37382


Simultaneous inhibition of discoidin domain receptor 1 and integrin αVβ3 radiosensitizes human glioblastoma cells

Elser, M.; Vehlow, A.; Juratli, T.; Cordes, N.

Glioblastomas (GBM) are the most common primary brain tumors in adults and associated with poor clinical outcomes due to therapy resistances and destructive growth. Interactions of cancer cells with the extracellular matrix (ECM) play a pivotal role in therapy resistances and tumor progression. In this study, we investigate the functional dependencies between the discoidin domain receptor 1 (DDR1) and the integrin family of cell adhesion molecules for the radioresponse of human glioblastoma cells. By means of an RNA interference screen on DDR1 and all known integrin subunits, we identified co-targeting of DDR1/integrin β3 to most efficiently reduce clonogenicity, enhance cellular radiosensitivity and diminish repair of DNA double strand breaks (DSB). Simultaneous pharmacological inhibition of DDR1 with DDR1-IN-1 and of integrins αVβ3/αVβ5 with cilengitide resulted in confirmatory data in a panel of 2D grown glioblastoma cultures and 3D gliospheres. Mechanistically, we found that key DNA repair proteins ATM and DNA-PK are altered upon DDR1/ integrin αVβ3 /integrin αVβ5 inhibition, suggesting a link to DNA repair mechanisms. In sum, the radioresistance of human glioblastoma cells can effectively be declined by co-deactivation of DDR1, integrin αVβ3 and integrin αVβ5.

Keywords: GBM; Integrins; Radiotherapy; DDR1

  • Open Access Logo American Journal of Cancer Research 13(2023)10, 4597-4612

Permalink: https://www.hzdr.de/publications/Publ-37381
Publ.-Id: 37381


Strong magnetoelastic coupling in MnCoSi compounds studied in pulsed magnetic fields

Zhang, F.; Bykov, E.; Gottschall, T.; van Dijk, N.; Brück, E.

The orthorhombic MnCoSi compounds have been found to present a large magnetoelastic coupling, which is regarded as the source for the magnetocaloric effect (MCE) and the magnetostrictive effect. As a result, these compounds are potential materials for caloric applications such as solid-state refrigeration. In the presentstudy, we offer fundamental insights in the magnetoelastic coupling in these compounds based on their structural, metamagnetic, and MCE behavior. The directly measured adiabatic temperature change (ΔTad) in different initial temperatures (down to 18 K) and pulsed magnetic fields (up to 40 T) presents a moderate MCE performance (the maximum ΔTad = –3.1 K for a field change of 13 T), which results from the metamagnetic behavior of these compounds. Furthermore, the magnetization measurements in pulsed (and static) magnetic fields indicate that the magnetoelastic coupling is significantly enhanced for increasing fields resulting in an improved saturation magnetization. The metamagnetic transition is continuously pushed to lower temperatures in higher fields. The phase diagram constructed from the experimental transition temperatures Tt and the critical magnetic fields μ0Hcr indicate that the transition is terminated below 18 K and that ferromagnetism is stabilized for fields above 22.3 T. Our results provide unique insights into the strong magnetoelastic coupling under high pulsed magnetic fields, providing guidelines for the design of giant magnetocaloric materials for future caloric applications.

Permalink: https://www.hzdr.de/publications/Publ-37380
Publ.-Id: 37380


Controlling the Propagation Asymmetry of Hyperbolic Shear Polaritons in Beta-Gallium Oxide

Matson, J.; Wasserroth, S.; Ni, X.; Obst, M.; Diaz-Granados, K.; Carini, G.; Maria Renzi, E.; Galiffi, E.; Folland, T. G.; Eng, L. M.; Klopf, J. M.; Mastel, S.; Armster, S.; Gambin, V.; Wolf, M.; Kehr, S. C.; Alu, A.; Paarmann, A.; Caldwell, J. D.

Structural anisotropy in crystals is crucial for controlling light propagation, particularly in the infrared spectral regime where optical frequencies overlap with crystalline lattice resonances, enabling light-matter coupled quasiparticles called phonon polaritons (PhPs). Exploring PhPs in anisotropic materials like hBN and MoO3 has led to advancements in light confinement and manipulation. In a recent study, PhPs in the monoclinic crystal β-Ga2O3 (bGO) were shown to exhibit strongly asymmetric propagation with a frequency dispersive optical axis. Here, using scanning near-field optical microscopy (s-SNOM), we directly image the symmetry-broken propagation of hyperbolic shear polaritons in bGO. Further, we demonstrate the control and enhancement of shear-induced propagation asymmetry by varying the incident laser orientation and polariton momentum using different sizes of nano-antennas. Finally, we observe significant rotation of the hyperbola axis by changing the frequency of incident light. Our findings lay the groundwork for the widespread utilization and implementation of polaritons in low-symmetry crystals.

Keywords: FEL; FELBE; s-SNOM; 2D Materials; THz; phonon polaritons; near-field; nanoscale

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Permalink: https://www.hzdr.de/publications/Publ-37379
Publ.-Id: 37379


Data publication: Validation experiments for gamma-ray densitometry uncertainty prediction algorithm in gas flow modulation

Marchini, S.; Bieberle, A.; Schubert, M.; Hampel, U.

The gas flow modulation technique is a recently proposed approach for measuring the axial gas dispersion coefficient in bubble columns. The approach uses a marginal sinusoidal distrubance on the gas inlet flow and relates the propagation of such disturbance in the column's axial direction to the axial gas dispersion coefficient. The approach requires to measure sinusoidally changing gas holdup in time with high accuracy. The presented data set was used to experimentally validate a newly developed simualtion algorithm for predicting the effect of various uncertainty sources on the measured holdup wave. The algorithm is able to predict the uncertianty related to the applycation of gamma-ray densitometry and of the data ensable-averaging approach. Experiments were preformed using an elliptical rotating disc able to mimik a controlled "material holdup wave", similar to the gas holdup wave measured in gas flow modulation.

Keywords: Gas flow modulation technique; axial dispersion coefficient; gamma-ray densitometry; uncertainty analysis

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Permalink: https://www.hzdr.de/publications/Publ-37377
Publ.-Id: 37377


Efficient ultrafast field-driven spin current generation for spintronic terahertz frequency conversion

Ilyakov, I.; Brataas, A.; de Oliveira, T.; Ponomaryov, O.; Deinert, J.-C.; Hellwig, O.; Faßbender, J.; Lindner, J.; Salikhov, R.; Kovalev, S.

Efficient generation and control of spin currents launched by terahertz (THz) radiation with subsequent ultrafast spin-to-charge conversion is the current challenge for the next-generation of high-speed communication and data processing units. Here, we demonstrate that THz light can efficiently drive coherent angular momentum transfer in nanometer-thick ferromagnet/heavy-metal heterostructures. This process is non-resonant and does neither require external magnetic fields nor cryogenics. The efficiency of this process is more than one order of magnitude higher as compared to the recently observed THz induced spin-pumping in MnF2 antiferromagnet. The coherently driven spin currents originate from the ultrafast spin Seebeck effect, caused by a THz-induced temperature imbalance in electronic and magnonic temperatures and fast relaxation of the electron-phonon system. Owing to the fact that the electron-phonon relaxation time is comparable with the period of a THz wave, the induced spin current results in THz second harmonic generation and THz optical rectification, providing a spintronic basis for THz frequency mixing and rectifying components.

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Permalink: https://www.hzdr.de/publications/Publ-37375
Publ.-Id: 37375


Double magnetic transitions and exotic field-induced phase in the triangular lattice antiferromagnets Sr3Co(Nb,Ta)2O9

Lal, S.; Sebastian, S. J.; Islam, S. S.; Saravanan, M. P.; Uhlarz, M.; Skourski, Y.; Nath, R.

Two triangular lattice antiferromagnets Sr3Co(Nb, Ta)2O9 with an effective jeff = 1/2 ofCo2+ are synthesized and their magnetic properties are investigated via magnetization and heat capacity measurements. The leading in-plane antiferromagnetic exchange coupling is estimated to be J/kB ≃ 4.7 and 5.8 K, respectively. Both compounds feature two-step magnetic transitions at low temperatures [(TN1 ≃ 1.47 K and TN2 ≃ 1.22 K) and (TN1 ≃ 0.88 K and TN2 ≃ 0.67 K), respectively], driven by weak easy-axis anisotropy. Under magnetic field, Sr3CoNb2O9 evinces a plateau at 1/3 magnetization. Interestingly, the high-field magnetization of Sr3CoTa2O9 reveals an exotic regime (between HS1 and HS2) below the fully polarized state in which the heat capacity at low temperatures is governed by a power law (Cp ∝ Tα) with a reduced exponent α ≃ 2. These results demonstrate an unusual field-induced state with gapless excitations in the strongly frustrated magnet Sr3CoTa2O9. The complete T -H phase diagram is discussed for both compounds.

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Permalink: https://www.hzdr.de/publications/Publ-37374
Publ.-Id: 37374


A universal route to efficient non-linear response via Thomson scattering in linear solids

Wen, Y.; Giorgianni, F.; Ilyakov, I.; Quan, B.; Kovalev, S.; Wang, C.; Vicario, C.; Deinert, J.-C.; Xiong, X.; Bailey, J.; Chen, M.; Ponomaryov, O.; Awari, N.; Rovere, A.; Sun, J.; Morandotti, R.; Razzari, L. F.; Aeppli, G.; Li, J.; Zhou, J.

Non-linear materials are cornerstones of modern optics and electronics. Strong dependence on the intrinsic properties of
particular materials, however, inhibits the at-will extension of demanding non-linear effects, especially those second-order
ones, to widely adopted centrosymmetric materials (for example, silicon) and technologically important burgeoning spectral
domains (for example, terahertz frequencies). Here we introduce a universal route to efficient non-linear responses enabled
by exciting non-linear Thomson scattering, a fundamental process in electrodynamics that was known to occur only in
relativistic electrons in metamaterial composed of linear materials. Such a mechanism modulates the trajectory of charges,
either intrinsically or extrinsically provided in solids, at twice the driving frequency, allowing second-harmonic generation at
terahertz frequencies on crystalline silicon with extremely large non-linear susceptibility in our proof-of-concept experiments.
By offering a substantially material-and frequency-independent platform, our approach opens new possibilities in the fields of
on-demand non-linear optics, terahertz sources, strong field light-solid interactions and integrated photonic circuits

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Permalink: https://www.hzdr.de/publications/Publ-37373
Publ.-Id: 37373


Optical Properties of MoSe2 Monolayer Implanted with Ultra-Low-Energy Cr Ions

Bui, M. N.; Rost, S.; Auge, M.; Zhou, L.; Friedrich, C.; Blügel, S.; Kretschmer, S.; Krasheninnikov, A.; Watanabe, K.; Taniguchi, T.; Hofsäss, H. C.; Grützmacher, D.; Kardynał, B. E.

This paper explores the optical properties of an exfoliated MoSe2 monolayer implanted with Cr + ions, accelerated to 25 eV. Photoluminescence of the implanted MoSe 2 reveals an emission line from Cr-related defects that is present only under weak electron doping. Unlike band-to-band transition, the Cr-introduced emission is characterized by nonzero activation energy, long lifetimes, and weak response to the magnetic field. To rationalize the experimental results and get insights into the atomic structure of the defects, we modeled the Cr-ion irradiation process using ab initio molecular dynamics simulations followed by the electronic structure calculations of the system with defects. The experimental and theoretical results suggest that the recombination of electrons on the acceptors, which could be introduced by the Cr implantation-induced defects, with the valence band holes is the most likely origin of the low-energy emission. Our results demonstrate the potential of low-energy ion implantation as a tool to tailor the properties of two-dimensional (2D) materials by doping.

Keywords: transition-metal dichalcogenide monolayer; ultra-low-energy ion implantation; MoSe2; van der Waals heterostructure; photoluminescence; molecular dynamics; density functional theory

Permalink: https://www.hzdr.de/publications/Publ-37372
Publ.-Id: 37372


Data publication: Design, Synthesis, and Biological Evaluation of Small Molecule Based Radioligands with Improved Pharmacokinetic Properties for Imaging of Programmed Death Ligand 1

Krutzek, F.; Donat, C.; Ullrich, M.; Stadlbauer, S.

Bei diesem Datensatz handelt es sich um die chemische Charakterisierung der Verbindungen, die in-vitro-, in-vivo- und ex-vivo-Daten.

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Permalink: https://www.hzdr.de/publications/Publ-37371
Publ.-Id: 37371


Radiomics predictive modeling from dual-time-point FDG PET Ki parametric maps: application to chemotherapy response in lymphoma

Samimi, R.; Shiri, I.; Ahmadyar, Y.; van den Hoff, J.; Kamali-Asl, A.; Rezaee, A.; Yousefirizi, F.; Geramifar, P.; Rahmim, A.

Background: To investigate the use of dynamic radiomics features derived from dual-time-point (DTP-feature) [18F]FDG PET metabolic uptake rate Ki parametric maps to develop a predictive model for response to chemotherapy in lymphoma patients. Methods: We analyzed 126 lesions from 45 lymphoma patients (responding n = 75 and non-responding n = 51) treated with chemotherapy from two different centers. Static and DTP radiomics features were extracted from baseline static PET images and DTP Ki parametric maps. Spearman’s rank correlations were calculated between static and DTP features to identify features with potential additional information. We first employed univariate analysis to determine correlations between individual features, and subsequently utilized multivariate analysis to derive predictive models utilizing DTP and static radiomics features before and after ComBat harmonization. For multivariate modeling, we utilized both the minimum redundancy maximum relevance feature selection technique and the XGBoost classifier. To evaluate our model, we partitioned the patient datasets into training/validation and testing sets using an 80/20% split. Different metrics for classification including area under the curve (AUC), sensitivity (SEN), specificity (SPE), and accuracy (ACC) were reported in test sets. Results: Via Spearman’s rank correlations, there was negligible to moderate correlation between 32 out of 65 DTP features and some static features (ρ < 0.7); all the other 33 features showed high correlations (ρ ≥ 0.7). In univariate modeling, no significant difference between AUC of DTP and static features was observed. GLRLM_RLNU from static features demonstrated a strong correlation (AUC = 0.75, p value = 0.0001, q value = 0.0007) with therapy response. The most predictive DTP features were GLCM_Energy, GLCM_Entropy, and Uniformity, each with AUC = 0.73, p value = 0.0001, and q value < 0.0005. In multivariate analysis, the mean ranges of AUCs increased following harmonization. Use of harmonization plus combining DTP and static features was shown to provide significantly improved predictions (AUC = 0.97 ± 0.02, accuracy = 0.89 ± 0.05, sensitivity = 0.92 ± 0.09, and specificity = 0.88 ± 0.05). All models depicted significant performance in terms of AUC, ACC, SEN, and SPE (p < 0.05, Mann–Whitney test). Conclusions: Our results demonstrate significant value in harmonization of radiomics features as well as combining DTP and static radiomics models for predicting response to chemotherapy in lymphoma patients. © 2023, The Author(s).

Keywords: Artificial intelligence; Dynamic PET; Engineered radiomics; Lymphoma; Predictive model; Radiomics

Permalink: https://www.hzdr.de/publications/Publ-37370
Publ.-Id: 37370


Data publication: Pulsating dissolution of crystalline matter: A transport- or surface-controlled process?

Schabernack, J.; Fischer, C.

KIMERA (Open Source KMC software):

  • Input file: kimera.input
  • Crystal structure: StructurePaperInna_noO.xyz
  • Output files: Calcite.box, Calcite.clayer, Calcite.data, Calcite.meandiscoord, Calcite.surface
  • KMC data evaluation file: KMC-KinkSites.xlsx

COMSOL:

  • COMSOL program files for two simulations: .mph files
     

Keywords: Surface reactivity; Pulsating dissolution; Kinetic Monte Carlo; Reactive transport; Calcite

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Permalink: https://www.hzdr.de/publications/Publ-37369
Publ.-Id: 37369


Data publication: STENCIL-NET for equation-free forecasting from data

Maddu, S.; Sturm, D.; Cheeseman, B. L.; Müller, C. L.; Sbalzarini, I. F.

Git repository for "STENCIL-NET for equation-free forecasting from data"

Keywords: data-driven modeling; stencil; neural network; forecasting; scientific computing

Related publications

  • Reseach data in external data repository
    Publication year 2023
    License: -
    Hosted on https://github.com/mosaic-group/STENCIL-NET: Link to location

Permalink: https://www.hzdr.de/publications/Publ-37367
Publ.-Id: 37367


STENCIL-NET for equation-free forecasting from data

Maddu, S.; Sturm, D.; Cheeseman, B. L.; Müller, C. L.; Sbalzarini, I. F.

We present an artificial neural network architecture, termed STENCIL-NET, for equation-free forecasting of spatiotemporal dynamics from data. STENCIL-NET works by learning a discrete propagator that is able to reproduce the spatiotemporal dynamics of the training data. This data-driven propagator can then be used to forecast or extrapolate dynamics without needing to know a governing equation. STENCIL-NET does not learn a governing equation, nor an approximation to the data themselves. It instead learns a discrete propagator that reproduces the data. It therefore generalizes well to different dynamics and different grid resolutions. By analogy with classic numerical methods, we show that the discrete forecasting operators learned by STENCIL-NET are numerically stable and accurate for data represented on regular Cartesian grids. A once-trained STENCIL-NET model can be used for equation-free forecasting on larger spatial domains and for longer times than it was trained for, as an autonomous predictor of chaotic dynamics, as a coarse-graining method, and as a data-adaptive de-noising method, as we illustrate in numerical experiments. In all tests, STENCIL-NET generalizes better and is computationally more efficient, both in training and inference, than neural network architectures based on local (CNN) or global (FNO) nonlinear convolutions.

Keywords: data-driven modeling; stencil; neural network; forecasting; scientific computing

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Permalink: https://www.hzdr.de/publications/Publ-37366
Publ.-Id: 37366


Design, Synthesis, and Biological Evaluation of Small Molecule Based Radioligands with Improved Pharmacokinetic Properties for Imaging of Programmed Death Ligand 1

Krutzek, F.; Donat, C.; Ullrich, M.; Stadlbauer, S.

Small molecules offer some advantages for developing PET tracers and are therefore a promising approach for imaging and therapy monitoring of PD-L1 positive tumors. Here, we report six biphenyl PD-L1 radioligands, using the NODA-GA-chelator for efficient copper-64 complexation. These radioligands contain varying numbers of sulfonic and/or phosphon-ic acid groups, serving as hydrophilizing units to lower the log D7.4 value down to –4.28. Binding affinities of compounds were evaluated using saturation binding and a real-time binding assay, with lowest binding affinity of 21 nM. Small ani-mal PET imaging revealed vastly different pharmacokinetic profiles, depending on the quantity and type of hydrophiliz-ing units. Of the investigated radioligands, [64Cu]Cu-3 showed the most favorable kinetics in vitro. This was also found in vivo, with a predominantly renal clearance and a specific uptake in the PD-L1-positive tumor. With further modifications, this compound could be a promising candidate for imaging of PD-L1 in the clinical setting.

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Permalink: https://www.hzdr.de/publications/Publ-37365
Publ.-Id: 37365


Raw data related to publication "Influence of engineered roughness microstructures on adhesion and turbulent resuspension of microparticles" by Banari et al. (2023)

Lecrivain, G.
ContactPerson: Lecrivain, Gregory

#Folder "Adhesion": Contains all raw data related to the adhesion force measurement. To plot the figure, run python3. plot.py

#Folder "SEM": each subfolder S1, S2 and S3 contains further high-resolution pictures taken with the SEM

#Folder "WindChannel": Contains all raw data related to the resuspensiob experiment performed in the winf channel. More Info in Windchannel/Readme.txt

Keywords: Particle resuspension; Turbulent gas flow; Aerosol transport

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Permalink: https://www.hzdr.de/publications/Publ-37363
Publ.-Id: 37363


Knowledge Graph Development as a Collaborative Process

Steinmeier, L.; van den Boogaart, K. G.; Schaller, T.

Establishing semantic data and knowledge graphs in scientific working groups is no easy feat. In most cases there is neither a user friendly tool chain nor experience with ontologies for the respective research field. But without a start, said experience can never be gained. The same is true for individuals that want to start into the field.

We thus see knowledge graph development not as a task of expert individuals that already know everything, but as a collaborative (learning) process of working groups and organisations. At the start of this process the right ontologies are not known and the individuals do not yet have experience with expressing information in knowledge graphs. Thus, a tool chain must provide basic knowledge to help newcomers to get started. It must also support the learning process and the selection of terms and ontologies, while users are already working with their own data and metadata. Additionally, the tool chain must support cooperation and lateral transfer of knowledge within organisations and working groups as well as between working groups world wide.

We therefore propose to establish a data infrastructure in every research organisation consisting of the following elements: An organisational knowledge graph, integration of (global) ID services, links to FAIR ontologies, policies, and a graph editing tool. This editing tool must support simultaneously the input of graph data, the extension of ontologies, the development of data structures, and finding and reusing existing ontologies and data structures not only from other persons inside the organisation but also from globally emerging metadata standards. While searching for a fitting term from a predefined set of ontologies, the tool would also allow for the creation of an internal term, when no fitting one is found. While trying to create a new term, fitting ones are automatically searched and proposed. The here proposed graph editing tool would provide the possibility to refactor existing data to newly selected ontologies, e.g. through replacing terms or whole structures, while keeping the original history in a git+GitLab like structure. This would also allow for access control and cooperation within the organisation and beyond. Such refactoring translations would also be described in terms of graph data and be published, so that others considering the same transition could use them without much effort.

We think that in the presented infrastructure users could establish processes that would foster harmonization and convergence of ontologies and data structures, while not impeding the collection of data and learning processes of individuals before harmonization is achieved.

Keywords: knowledge graph; collaborative data development; metadata harmonization; research data interoperability

  • Lecture (Conference) (Online presentation)
    HMC Conference 2023, 10.-12.10.2023, online, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37362
Publ.-Id: 37362


Hydrogen Transport Between Layers of Transition Metal-Dichalcogenides

Eren, I.; Yun, A.; Kuc, A. B.

Hydrogen is a crucial source of green energy and has been extensively studied for its potential usage in fuel cells. The advent of two-dimensional crystals (2DCs) has taken hydrogen research to new heights, enabling it to tunnel through layers of 2DCs or be transported within voids between the layers, as demonstrated in recent experiments by Geim’s group. In this study, we investigate how the composition and stacking of transition-metal dichalcogenide (TMDC) layers influence the transport and self-diffusion coefficients (D) of hydrogen atoms using well-tempered metadynamics simulations. Our findings show that modifying either the transition metal or the chalcogen atoms significantly affects the free energy barriers (ΔF) and, consequently, the self-diffusion of hydrogen atoms between the 2DC layers. In the Hhh polytype (2H stacking), MoSe2 exhibits the lowest ΔF, while WS2 has the highest, resulting in the largest D for the former system. Additionally, hydrogen atoms inside the RMh (or 3R) polytype encounter more than twice lower energy barriers and, thus, much higher diffusivity compared to those within the most stable Hhh stacking. These findings are particularly significant when investigating twisted layers or homo- or heterostructures, as different stacking areas may dominate over others, potentially leading to directional transport and interesting materials for ion or atom sieving.

Keywords: hydrogen transport; two-dimensional materials; transition-metal dichalcogenides; well-tempered metadynamics simulations; self-diffusion coefficients

Permalink: https://www.hzdr.de/publications/Publ-37361
Publ.-Id: 37361


supplementary material for bubble trajectories

Shi, P.; Tholan, V.; Sommer, A.-E.; Heitkam, S.; Eckert, K.; Kevin, G.; Rzehak, R.

supplementary material for bubble trajectories

Keywords: spherical bubble; inclined channel; drag force; lift force; wake bending

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Permalink: https://www.hzdr.de/publications/Publ-37360
Publ.-Id: 37360


Forces on a nearly spherical bubble rising in an inclined channel flow

Shi, P.; Tholan, V.; Sommer, A.-E.; Heitkam, S.; Eckert, K.; Kevin, G.; Rzehak, R.

The dynamics of a sub-millimeter air bubble rising at a bubble Reynolds number of about 100 in water in an inclined, laminar channel flow is investigated experimentally. In this configuration which is relevant in modern separation technologies for valuable particles, the bubble is undergoing a cross-stream motion, as the buoyancy force is not aligned with the undisturbed liquid flow. From measurements of bubble velocities and trajectories we estimate the drag and lift forces on the bubble at two different channel Reynolds numbers. The results are compared with their streamwise counterparts, i.e. in the configuration where the bubble rises largely along a streamline of the undisturbed liquid flow. For the lower channel Reynolds number, the cross-stream effects are only small. For the larger channel Reynolds number however, the drag coefficient is found to be notably larger than its streamwise counterpart. The lift coefficient may be either larger or smaller than its streamwise counterpart depending on the detailed local flow conditions. In particular, its value is non-zero when the bubble crosses the channel centerline where the shear rate is zero. These deviations are found to be closely connected with the bending of the bubble wake as well as the finite value of the angle formed between the bubble slip velocity and the velocity of the liquid flow.

Keywords: spherical bubble; inclined channel; drag force; lift force; wake bending

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  • Secondary publication expected from 23.09.2024

Permalink: https://www.hzdr.de/publications/Publ-37359
Publ.-Id: 37359


Data publication: All-electrical operation of a Curie switch at room temperature

Iurchuk, V.; Kozlov, O.; Sorokin, S.; Zhou, S.; Lindner, J.; Reshetniak, S.; Kravets, A.; Polishchuk, D.; Korenivski, V.

This dataset contains the experimental and analytical data used and discussed in the publication "All-Electrical Operation of a Curie Switch at Room Temperature" (Phys. Rev. Applied 20, 024009 – Published 3 August 2023).

Keywords: Magnetoresistance; Magnetic hysteresis; Vibrating sample magnetometry; Spin valve; Thermomagnetic effects; RKKY interaction

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Permalink: https://www.hzdr.de/publications/Publ-37358
Publ.-Id: 37358


Overarching Data Management Ecosystem at HZDR

Knodel, O.; Gruber, T.; Kelling, J.; Lokamani, M.; Müller, S.; Pape, D.; Voigt, M.; Juckeland, G.

When dealing with research data management, researchers at Helmholtz-
Zentrum Dresden – Rossendorf (HZDR) face a variety of systems and tools. These
range from the project planning phase (proposal management, data management plans
and policies), over documentation during the experiment or simulation campaign, to the
publication (collaborative authoring tools, metadata catalogs, publication systems, data
repositories). In addition, modern research projects usually are required to interact with
a variety of software stacks and workflow management systems to allow comprehensi-
ble and FAIR science on the underlying IT infrastructure (HPC, data storage, network
file systems, archival). This article first demonstrates the data management systems
and services provided at HZDR, followed by an overview of a self-developed guidance
system. It is concluded by a real-world example.

Keywords: research data management; data life cycle; workflows; metadata; FAIR; data provenance; HELIPORT

  • Open Access Logo Contribution to proceedings
    1st Conference on Research Data Infrastructure, 12.-14.09.2023, Karlsruhe, Deutschland
    Proceedings of the 1st Conference on Research Data Infrastructure, Hannover: TIB Open Publishing
    DOI: 10.52825/CoRDI.v1i.277
    ISSN: 2941-296X

Permalink: https://www.hzdr.de/publications/Publ-37357
Publ.-Id: 37357


Two-Step Approach in Metadata Management for Data Publications at Research Centres

Gruber, T.; Schlenvoigt, H.-P.; Knodel, O.; Tippey, K. E.; Juckeland, G.

Data repositories like Zenodo have a limited list of metadata to search for. Metadata catalogues are designed to provide a community-specific parameters search, but their deployment has just started. These catalogues require metadata standards for interoperability, which in turn are often in development for many communities. To support publications with a metadata standard in the future, a two-step concept is presented in this article. It discusses how the electronic documentation should be constructed, in order to convert this later into a standardised schema for publication. We will present examples from the laser-plasma community for both steps, firstly how we deal with the complex challenges of metadata management and secondly for methods for developing metadata schemas.

Keywords: Data Management; Workflows; Metadata; Data Provenance

  • Open Access Logo Contribution to proceedings
    1st Conference on Research Data Infrastructure, 12.-14.09.2023, Karlsruhe, Deutschland
    Proceedings of the Conference on Research Data Infrastructure, Hannover: TIB Open Publishing
    DOI: 10.52825/cordi.v1i.377

Permalink: https://www.hzdr.de/publications/Publ-37356
Publ.-Id: 37356


Data-Driven Research for the Discovery of Novel Two-Dimensional and Ionic Materials

Friedrich, R.

While two-dimensional (2D) materials are traditionally derived from bulk layered
compounds bonded by weak van der Waals (vdW) forces, the recent surprising
experimental realization of non-vdW 2D compounds obtained from non-layered
crystals [1] foreshadows a new direction in 2D systems research.
Here, several dozens of candidates of this novel materials class are presented derived
from filtering the AFLOW materials database (see Fig. 1) in conjunction with
autonomous ab initio calculations [2,3]. The oxidation state of the surface cations of
the 2D sheets is an enabling descriptor regarding the manufacturing of these systems
as it determines their exfoliation energy: small oxidation states promote easy peel off
[2]. When extending the set from oxides to sulfides and chlorides, the exfoliation
energy becomes ultra low due to strong surface relaxations [3]. The candidates exhibit
a wide range of appealing electronic, optical and magnetic properties making these
systems an attractive platform for fundamental and applied nanoscience.
[1] A. Puthirath Balan et al., Nat. Nanotechnol. 13, 602 (2018).
[2] R. Friedrich et al., Nano Lett. 22, 989 (2022).
[3] T. Barnowsky et al., Adv. El. Mats., in press (2023).

Related publications

  • Invited lecture (Conferences)
    Invited talk at BTU Cottbus-Senftenberg, 20.01.2023, Cottbus, BRD

Permalink: https://www.hzdr.de/publications/Publ-37355
Publ.-Id: 37355


Discovering Two-Dimensional Non-van der Waals Materials by Data-driven Research

Friedrich, R.

While two-dimensional (2D) materials are traditionally associated with bulk layered
compounds bonded by weak van der Waals (vdW) interactions, the recent surprising
experimental realization of non-vdW 2D systems obtained from non-layered crystals [1,2]
opens up a new direction. These materials show several distinct differences to traditional
2D sheets as their surface was revealed to be terminated by cations rather than anions.
Here, we outline several dozens of candidates of this novel materials class derived from
employing data-driven research principles in conjunction with autonomous ab initio
calculations [3,4] (Figure 1). The oxidation state of the surface cations of the 2D sheets
turns out to be an enabling descriptor regarding the manufacturing of these systems as
it determines their exfoliation energy: small oxidation states promote easy peel off [3].
When extending the set from oxides to sulfides and chlorides, the exfoliation energy
becomes ultra low due to strong surface relaxations [4]. The candidates exhibit a wide
range of appealing electronic, optical and in particular magnetic properties making these
systems an attractive platform for fundamental and applied nanoscience.
[1] A. Puthirath Balan et al., Nat. Nanotechnol. 13, 602 (2018).
[2] A. Puthirath Balan et al., Chem. Mater. 30, 5923 (2018).
[3] R. Friedrich et al., Nano Lett. 22, 989 (2022).
[4] T. Barnowsky et al., Adv. Electron. Mater. 9, 2201112 (2023).

Related publications

  • Invited lecture (Conferences)
    2nd China-Germany bilateral meeting on topological devices, 2D materials and the future of spintronics, 03.-04.08.2023, Mainz, BRD

Permalink: https://www.hzdr.de/publications/Publ-37354
Publ.-Id: 37354


Data-Driven Research for the Discovery of Novel Two-Dimensional and Ionic Material

Friedrich, R.

Data-Driven Research for the Discovery of Novel Two-Dimensional and Ionic Material

Related publications

  • Invited lecture (Conferences)
    Retreat of the Felser Department of the Max Planck Institute for the Chemical Physics of Solids, 11.-13.01.2023, Bad Schandau, BRD

Permalink: https://www.hzdr.de/publications/Publ-37353
Publ.-Id: 37353


Two-Dimensional Non-van der Waals Materials from Data-Driven Research

Friedrich, R.; Barnowsky, T.; Ghorbani-Asl, M.; Curtarolo, S.; Krasheninnikov, A. V.

While two-dimensional (2D) materials are traditionally derived from
bulk layered compounds bonded by weak van der Waals (vdW) forces,
the recent surprising experimental realization of non-vdW 2D compounds
obtained from non-layered crystals [1] foreshadows a new direction
in 2D systems research.
Here, we present several dozens of candidates of this novel materials
class derived from applying data-driven research methodologies
in conjunction with autonomous ab initio calculations [2,3]. We find
that the oxidation state of the surface cations of the 2D sheets is an
enabling descriptor regarding the manufacturing of these systems as
it determines their exfoliation energy: small oxidation states promote
easy peel off [2]. When extending the set from oxides to sulfides and
chlorides, the exfoliation energy becomes ultra low due to strong surface
relaxations [3]. The candidates exhibit a wide range of appealing
electronic, optical and magnetic properties making these systems an
attractive platform for fundamental and applied nanoscience.
[1] A. Puthirath Balan et al., Nat. Nanotechnol. 13, 602 (2018).
[2] R. Friedrich et al., Nano Lett. 22, 989 (2022).
[3] T. Barnowsky et al., submitted (2022).

Related publications

  • Lecture (Conference)
    DPG Spring Meeting of the Condensed Matter Section (SKM) 2023, 26.-31.03.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37352
Publ.-Id: 37352


Efficient workflow for treating thermal and zero-point contributions to formation enthalpies

Friedrich, R.; Esters, M.; Oses, C.; Ki, S.; Brenner, M. J.; Hicks, D.; Mehl, M. J.; Toher, C.; Curtarolo, S.

The formation enthalpy, quantifying the enthalpy of a compound with
respect to its elemental references, is a key parameter for predicting the
thermodynamic stability of materials thus enabling data-driven materials
design. Although for instance zero-point vibrational and thermal
contributions to the formation enthalpy can be quite substantial reaching
absolute values of up to ∼ 50 meV/atom for ionic systems such as
oxides, they are often neglected in ab initio workflows.
Here, we first calculate the thermal and zero-point contributions accurately
from a quasi-harmonic Debye model. At room temperature,
they largely cancel each other due to the different bond stiffness of
compound and references reducing the total vibrational contribution
to maximally ∼ 20 meV/atom [1]. Moreover, the vibrational contributions
can be parametrized within the coordination corrected enthalpies
(CCE) method completely eliminating the need to compute
these terms explicitly. On this basis, using only 0 K ab initio data
as input, a workflow can be designed providing access to formation
enthalpies at different temperatures from the AFLOW-CCE tool [2].
[1] R. Friedrich et al., npj Comput. Mater. 5, 59 (2019).
[2] R. Friedrich et al., Phys. Rev. Mater. 5, 043803 (2021).

Related publications

  • Lecture (Conference)
    DPG Spring Meeting of the Condensed Matter Section (SKM) 2023, 26.-31.03.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37351
Publ.-Id: 37351


Discovering Two-Dimensional Non-van der Waals Materials

Friedrich, R.; Barnowsky, T.; Ghorbani-Asl, M.; Curtarolo, S.; Krasheninnikov, A. V.

While two-dimensional (2D) materials are traditionally associated with bulk layered compounds
bonded by weak van der Waals (vdW) interactions, the recent surprising experimental realization of
non-vdW 2D compounds obtained from non-layered crystals [1,2] opens up a new direction in 2D
systems research. These materials show several distinct differences to traditional 2D sheets as their
surface was revealed to be terminated by cations rather than anions. Here, we outline several
dozens of candidates of this novel materials class derived from employing data-driven research
principles in conjunction with autonomous ab initio calculations [3,4] (Figure 1). The oxidation state
of the surface cations of the 2D sheets turns out to be an enabling descriptor regarding the
manufacturing of these systems as it determines their exfoliation energy: small oxidation states
promote easy peel off [3]. When extending the set from oxides to sulfides and chlorides, the
exfoliation energy becomes ultra low due to strong surface relaxations [4]. The materials also pass
several tests validating their vibrational and dynamic stability. The candidates exhibit a wide range of
appealing electronic, optical and in particular magnetic properties making these systems an
attractive platform for fundamental and applied nanoscience.
References
[1] A. Puthirath Balan et al., Nat. Nanotechnol. 13 (2018) 602.
[2] A. Puthirath Balan et al., Chem. Mater. 30 (2018) 5923.
[3] R. Friedrich et al., Nano Lett. 22 (2022) 989.
[4] T. Barnowsky et al., Adv. Electron. Mater. (2023) 2201112.

Related publications

  • Lecture (Conference)
    chem2Dmat, 15.-18.05.2023, Bologna, Italien

Permalink: https://www.hzdr.de/publications/Publ-37350
Publ.-Id: 37350


Phenotype-preserving metric design for high-content image reconstruction by generative inpainting

Sharma, V.; Yakimovich, A.

In the past decades, automated high-content microscopy demonstrated its ability to deliver large quantities of image-based data powering the versatility of phenotypic drug screening and systems biology applications. However, as the sizes of image-based datasets grew, it became infeasible for humans to control, avoid and overcome the presence of imaging and sample preparation artefacts in the images. While novel techniques like machine learning and deep learning may address these shortcomings through generative image inpainting, when applied to sensitive research data this may come at the cost of undesired image manipulation. Undesired manipulation may be caused by phenomena such as neural hallucinations, to which some artificial neural networks are prone. To address this, here we evaluate the state-of-the-art inpainting methods for image restoration in a high-content fluorescence microscopy dataset of cultured cells with labelled nuclei. We show that architectures like DeepFill V2 and Edge Connect can faithfully restore microscopy images upon fine-tuning with relatively little data. Our results demonstrate that the area of the region to be restored is of higher importance than shape. Furthermore, to control for the quality of restoration, we propose a novel phenotype-preserving metric design strategy. In this strategy, the size and count of the restored biological phenotypes like cell nuclei are quantified to penalise undesirable manipulation. We argue that the design principles of our approach may also generalise to other applications.

Keywords: Deep Learning; Generative Inpainting; Computer Vision; Fluorescence Microscopy; Sample Preparation Artefacts; Image Reconstruction; Metric

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Permalink: https://www.hzdr.de/publications/Publ-37349
Publ.-Id: 37349


Data publication: A weak-labelling and deep learning approach for in-focus object segmentation in 3D widefield microscopy

Li, R.; Kudryashev, M.; Yakimovich, A.

D. rerio 3D microscopy and in-focus pixel segmentation.

Keywords: weak-labeling; deep neural network; widefield microscopy; surrogate model

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Permalink: https://www.hzdr.de/publications/Publ-37348
Publ.-Id: 37348


Analysis of loss of flow without scram test in the FFTF reactor – Part II: System thermal hydraulics with point neutron kinetics

Ponomarev, A.; Nikitin, E.; Fridman, E.

This study presents a benchmark analysis of an unprotected loss of flow transient in a sodium-cooled fast reactor at the Fast Flux Test Facility (FFTF), carried out as part of an IAEA coordinated research project. Three codes, namely Serpent (Monte Carlo), DYN3D (3D nodal diffusion) and ATHLET (system thermal hydraulics), were employed in the benchmark exercise. Two distinct modeling approaches were utilized: 1) stand-alone ATHLET with point kinetics (PK) and system thermal hydraulics (TH); and 2) coupled DYN3D/ATHLET with spatial kinetics (SK) and system TH. Neutronics data essential for both approaches were generated using Serpent. The study is organized into three parts.

Part I presented a summary of the preparation of neutronics data for PK or coupled SK/TH simulations and included the outcomes of the static neutronics stage of the benchmark. The main focus lay on verifying the cross-section generation method for DYN3D by comparing its results against the reference Monte Carlo solutions obtained with Serpent.

Part II provides a detailed description of the ATHLET TH model of the system. This model is thoroughly evaluated by comparing the results with the ANL benchmark solution and experimental data for the transient. Furthermore, a sensitivity analysis is conducted to explore various modeling options and assess their impact on the simulation results.

Part III will showcase the transient calculation results using the two modeling approaches. Additionally, an adaptive decay heat model for nodal codes will be introduced. The performance of both modeling approaches will be assessed by comparing their results to the available experimental data.

Keywords: ATHLET; FFTF; Gas Expansion Module; loss of flow; point kinetics; SFR; unprotected transient

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37346
Publ.-Id: 37346


Analysis of loss of flow without scram test in the FFTF reactor – Part I: preparation of neutronics data

Nikitin, E.; Fridman, E.; Ponomarev, A.

This study presents a benchmark analysis of an unprotected loss of flow transient in a sodium-cooled fast reactor at the Fast Flux Test Facility (FFTF), carried out as part of an IAEA coordinate research project. Three codes, namely Serpent (Monte Carlo), DYN3D (3D nodal diffusion) and ATHLET (system thermal hydraulics), were employed in the benchmark exercise. Two distinct modeling approaches were utilized: 1) stand-alone ATHLET with point kinetics (PK) and system thermal hydraulics (TH); and 2) coupled DYN3D/ATHLET with spatial kinetics (SK) and system TH. Neutronics data essential for both approaches were generated using Serpent. The study is organized into three parts.

Part I presents a summary of the preparation of neutronics data for PK or coupled SK/TH simulations and includes the outcomes of the static neutronics stage of the benchmark. The main focus lies on verifying the cross-section generation method for DYN3D by comparing its results against the reference Monte Carlo solutions obtained with Serpent.

Part II will provide a detailed description of the ATHLET TH model of the system. This model will be thoroughly evaluated by comparing the results with the ANL benchmark solution and experimental data for the transient. Furthermore, a sensitivity analysis will be conducted to explore various modeling options and assess their impact on the simulation results.

Part III will showcase the transient calculation results using the two modeling approaches. Additionally, an adaptive decay heat model for nodal codes will be introduced. The performance of both modeling approaches will be assessed by comparing their results to the available experimental data.

Keywords: SFR; Serpent; DYN3D; neutronics benchmark; homogenized cross section

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37345
Publ.-Id: 37345


Variational Formulations for Solving PDEs with Non-Smooth Solutions using Non-Linear Surrogates

Suarez Cardona, J. E.

This talk intends to address the challenge of solving Partial Differential Equations (PDEs) with smooth
or non-smooth solutions by formulating variational PDE formulations resulting in a soft-constrained
optimization problem. The flexibility of the variational formulation enables us to use hybrid non-linear
surrogates to approximate discontinuous shocks while solving forward or inverse PDE problems. We
first explore general concepts and tools necessary for solving PDEs under a variational formulation with
general non-linear surrogates and boundary conditions. We then compare the numerical performance of
Physics Informed Neural Networks (PINNs) as surrogates against Polynomial Surrogate Models (PSMs).
Our goal is to open up the discussion regarding the class of problems that genuinely require the use of
Neural Networks. Our findings indicate that PSMs outperform PINNs by several orders of magnitude in
both accuracy and runtime. Furthermore, we introduce a new method for approximating discontinuous
functions using modified global spectral methods. We extend this method to solve PDEs with nonsmooth
solutions, providing an innovative solution to a highly challenging problem.

  • Open Access Logo Poster
    NoLineal 2023, 26.06.2023, Barcelona, Spain

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Permalink: https://www.hzdr.de/publications/Publ-37344
Publ.-Id: 37344


High-field EPR of copper(II)–nitroxide compound exhibiting three-step phase transition: structural insights from the field-induced sample orientation

Tumanov, S. V.; Ponomaryov, O.; Maryunina, K. Y.; Bogomyakov, A. S.; Ovcharenko, V. I.; Zvyagin, S.; Fedin, M. V.; Veber, S. L.

Copper(II)–nitroxide based Cu(hfac)2LR compounds exhibit unusual magnetic behavior that can be induced by various stimuli. In many aspects, the magnetic phenomena observed in Cu(hfac)2LR are similar to classical spin-crossover behavior. However, these phenomena originate from polynuclear exchangecoupled spin clusters Cu2+–O–N< or >N–O–Cu2+–O–N<. Such peculiarities may result in additional multifunctionality of Cu(hfac)2LR compounds, making them promising materials for spintronic applications. Herein, we investigate the Cu(hfac)2LMeMe material, which demonstrates a three-step temperature-induced magnetostructural transition between high-temperature, low-temperature, and intermediate states, as revealed by magnetometry. Two main steps were resolved using variable-temperature Fourier-transform infrared and Q-band electron paramagnetic resonance (EPR) spectroscopies. The intermediate-temperature states (∼40–90 K) are characterized by the coexistence of two types of copper(II)–nitroxide clusters, corresponding to the low-temperature and high-temperature phases. High-field EPR experiments revealed the effect of partial alignment of Cu(hfac)2LMeMe microcrystals in a strong (>20 T) magnetic field. This effect was used to unveil the structural features of the low-temperature phase of Cu(hfac)2LMeMe, which were inaccessible using single-crystal X-ray diffraction (XRD) technique. In particular, high-field EPR allowed us to determine the relative direction of the Jahn–Teller axes in CuO6 and CuO4N2 units.

Permalink: https://www.hzdr.de/publications/Publ-37342
Publ.-Id: 37342


Non-axisymmetric standard magnetorotational instability in the upcoming DRESDYN-MRI experiments -- linear and nonlinear dynamics

Mishra, A.; Mamatsashvili, G.; Stefani, F.

Magnetorotational instability (MRI) is the most likely mechanism for efficient transport of angular momentum in accretion disks. However, despite numerous efforts, the quest for an unambiguous realization of MRI in experiments is still ongoing. To conclusively identify MRI in the laboratory, a large Taylor-Couette experiment with liquid sodium is under construction at the Helmholtz-Zentrum Dresden-Rossendorf within the DRESDYN project. Recently, we have determined the optimal range of parameters for the onset of an axisymmetric mode of the standard MRI (SMRI) with a purely axial background magnetic field and analyzed its nonlinear evolution, saturation and scaling properties in the context of the DRESDYN-MRI experiment. In this sequel paper, we continue SMRI studies and investigate the linear and nonlinear dynamics of non-axisymmetric modes of the instability in a similar magnetized Taylor-Couette setup. For the linear stability analysis, we use $Pm=\nu/\eta \sim 10^{-5}$ typical of liquid sodium used in the experiment. We show that the achievable magnetic Reynolds $Rm\sim 40$ and Lundquist $Lu\sim10$ numbers in this experiment are large enough for the growth of non-axisymmetric $|m|=1$ SMRI modes. For fixed $\mu$, the critical $Rm_c$ for the onset of non-axisymmetric SMRI is about 2-3 time higher than that of axisymmetric SMRI. We follow the evolution of these modes from their exponential growth in the linear regime all over to nonlinear saturation. The structure of the saturated state and its scaling properties with respect to Reynolds number $Re$ are analyzed, which is relevant and important for the DRESDYN-MRI experiment having very high Reynolds numbers ($\sim 10^6$). We show that for $Re \lesssim 10^4$, the magnetic energy of non-axisymmetric SMRI modes does not saturate and eventually decays due to the modification of the radial shear profile of the mean azimuthal velocity by the nonlinear axisymmetric SMRI, that is, the modified shear profile appears to be stable against non-axisymmetric modes. By contrast, for large $Re \gtrsim 10^4$, a sudden rapid growth and saturation of the magnetic energy of non-axisymmetric modes occur, which are radially localized in the turbulent boundary layer near the inner cylinder wall. The saturation amplitude of the non-axisymmetric modes is always a few orders smaller than that of the axisymmetric SMRI mode. We further show that the scaling relations for magnetic energy and torque in the saturated state of SMRI derived for axisymmetric modes in our previous study well carry over to $|m|\geq 1$ non-axisymmetric ones.

Keywords: Taylor-Couette system; Astrophysical fluid dynamics; Flow instability; Magnetohydrodynamic turbulence; Magnetohydrodynamics; Nonlinear dynamics in fluids; Shear flows; Turbulence

Permalink: https://www.hzdr.de/publications/Publ-37341
Publ.-Id: 37341


Synthesis of Single Crystals of ε-Iron and Direct Measurements of Its Elastic Constants

Dewaele, A.; Amadon, B.; Bosak, A.; Svitlyk, V.; Occelli, F.

Seismology finds that Earth’s solid inner core behaves anisotropically. Interpretation of this requires a knowledge of crystalline elastic anisotropy of its constituents—the major phase being most likely ε-Fe, stable only under high pressure. Here, single crystals of this phase are synthesized, and its full elasticity tensor is measured between 15 and 33 GPa at 300 K. It is calculated under the same conditions, using the combination of density functional theory and dynamical mean field theory, which describes explicitly electronic correlation effects. The predictive power of this scheme is checked by comparison with measurements; it is then used to evaluate the crystalline anisotropy in ε-Fe under higher density. This anisotropy remains of the same amplitude up to densities typical of Earth’s inner core.

Permalink: https://www.hzdr.de/publications/Publ-37340
Publ.-Id: 37340


A comprehensive review of numerical and experimental research on the thermal-hydraulics of two-phase flows in vertical rod bundles

Tas-Köhler, S.

Thermal-hydraulic analysis of two-phase flow plays a crucial role in the optimal design of nuclear fuel assemblies and in nuclear safety. This paper presents the state of the art in two-phase flow hydrodynamics and heat transfer in nuclear fuel assemblies. A comprehensive review of experimental and CFD methods used in the last 30 years to analyse the thermal-hydraulic characteristics of sub-channels in rod bundle geometries under different flow conditions (adiabatic and boiling two-phase flow) is presented. The effects of design parameters, e.g. rod-pitch length, mixing vane angle, and flow parameters, e.g. pressure, mass flux and heat flux, on flow hydrodynamics and heat transfer performance are summarized. In addition, the capabilities of CFD modelling of two-phase in rod bundles are discussed. Moreover, based on the existing studies, some recommendations for future studies are given.

Keywords: Rod bundle; CFD; Experimental study; Two-phase flow; Flow hydrodynamics; Heat transfer

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  • Secondary publication expected from 26.12.2024

Permalink: https://www.hzdr.de/publications/Publ-37339
Publ.-Id: 37339


Ultra-short pulse laser acceleration of protons to 80 MeV from cryogenic hydrogen jets tailored to near-critical density

Rehwald, M.; Assenbaum, S.; Bernert, C.; Brack, F.-E.; Bussmann, M.; Cowan, T.; Curry, C. B.; Fiuza, F.; Garten, M.; Gaus, L.; Gauthier, M.; Göde, S.; Göthel, I.; Glenzer, S. H.; Huang, L.; Huebl, A.; Kim, J. B.; Kluge, T.; Kraft, S.; Kroll, F.; Metzkes-Ng, J.; Miethlinger, T.; Löser, M.; Obst-Huebl, L.; Reimold, M.; Schlenvoigt, H.-P.; Schoenwaelder, C.; Schramm, U.; Siebold, M.; Treffert, F.; Yang, L.; Ziegler, T.; Zeil, K.

Laser plasma-based particle accelerators attract great interest in fields where conventional accelerators reach limits based on size, cost or beam parameters. Despite the fact that particle in cell simulations have predicted several advantageous ion acceleration schemes, laser accelerators have not yet reached their full potential in producing simultaneous high-radiation doses at high particle energies. The most stringent limitation is the lack of a suitable high-repetition rate target that also provides a high degree of control of the plasma conditions required to access these advanced regimes. Here, we demonstrate that the interaction of petawatt-class laser pulses with a pre-formed micrometer-sized cryogenic hydrogen jet plasma overcomes these limitations enabling tailored density scans from the solid to the underdense regime. Our proof-of-concept experiment demonstrates that the near-critical plasma density profile produces proton energies of up to 80 MeV. Based on hydrodynamic and three-dimensional particle in cell simulations, transition between different acceleration schemes are shown, suggesting enhanced proton acceleration at the relativistic transparency front for the optimal case.

Keywords: Laser-produced plasmas; Plasma-based accelerators; Laser proton acceleration

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Permalink: https://www.hzdr.de/publications/Publ-37338
Publ.-Id: 37338


A Framework for Using FAIR Vocabularies in Every-Day Data

Steinmeier, L.; Rau, F.

Abstract

Semantics, i.e. terms and their meaning, can be shared, agreed upon, and used in data to make such data more FAIR, especially in terms of interoperability and reusability. The currently most often used technology for machine-actionable vocabularies of semantic terms are RDF-based ontologies (RDF = the W3C Resource Description Framework). But while the RDF has been around for about 20 years, there is still no broadly known tooling for using ontology terms during routine data entry and design.

To address this problem, we are implementing a data development framework that builds on semantic vocabularies as one of its core elements. This framework will provide a graphical interface where users can build their data (structures) in the form of knowledge graphs, i.e. nodes and edges that correspond to semantic vocabulary terms plus “raw values” (e.g. strings or numbers). This graph data editor will also support tables and forms as more compact graph elements for entity and attribute lists respectively.

In the editor, users will also get development support much like in IDEs (integrated development environments) for programming languages, e.g. by showing vocabulary term annotations on hover, auto-completing graph elements expected with specific terms, or suggesting existing terms and data structures when users are creating their own.

These support features together with the graph data editor will be embedded in the before mentioned data development framework. Within this framework an organization can choose desired ID services (e.g. ORCID, DOI, or in-house databases), set common vocabularies (e.g. QUDT [1] for units or BFO [2] as a top-level ontology), and have a central knowledge graph that all members can contribute to. (Groups of) users will be able to build their own graph data sets using git+GitLab for provenance and project management together with the organization’s ID services and vocabularies.

Acknowledgements

This work is being done as part of the Helmholtz Metadata Collaborations efforts to improve the metadata management in the German Helmholtz Association of Research Centers.

References

1. FAIRsharing.org: QUDT; Quantities, Units, Dimensions and Types, DOI: 10.25504/FAIRsharing.d3pqw7, Last Edited: Friday, May 6th 2022, 11:03, Last Editor: delphinedauga, accessed: 27 July 2023.
2. Arp, Robert, Barry Smith, and Andrew D. Spear, Building Ontologies With Basic Formal Ontology (Cambridge, MA, 2015; online edn, MIT Press Scholarship Online, 19 May 2016), DOI: 10.7551/mitpress/9780262527811.001.0001 , accessed: 27 July 2023.

  • Open Access Logo Lecture (Conference) (Online presentation)
    Vocabulary Symposium 2023, 14.-15.11.2023, Canberra, Australia
    DOI: 10.5281/zenodo.10052293

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Permalink: https://www.hzdr.de/publications/Publ-37336
Publ.-Id: 37336


Deciphering the diagenetic evolution of the lower Carnian succession in the Gorno and Pian Resinelli sulphide mining districts (Southalpine Domain, N Italy)

Summino, L.; Giorno, M. A.; Barale, L.; Bertok, C.; Martire, L.

The stratabound Mississippi Valley-type (MVT) sulphide deposits of the Gorno
and Piani Resinelli mining districts are hosted in the lower Carnian carbonate
succession, mainly peritidal limestones, of the Lombardian Basin (Southalpine
Domain, Northern Italy). In addition to the formation of the well-known sulphide
deposits, these carbonate sediments experienced a complex diagenetic evolution,
including different stages of dolomitization, silicification, dissolution, brecciation,
calcite cement precipitation. Stratigraphic and petrographic features suggest
that, apart from an early calcite cementation and a first penecontemporaneous
dolomitization affecting the supratidal beds, diagenetic processes and sulphide
precipitation, are intimately and genetically associated. They document the
occurrence of a Carnian hydrothermal system developed shortly after deposition
at shallow burial depth, confirmed by fluid inclusion microthermometry and U-Pb
radiometric datings.

Keywords: sulphide deposits; Carnian; hydrothermal system; carbonate diagenesis; Gorno-Piani Resinelli districts

  • Rendiconti online della Società Geologica Italiana 59(2023), 97-104
    DOI: 10.3301/ROL.2023.15

Permalink: https://www.hzdr.de/publications/Publ-37335
Publ.-Id: 37335


Operational Experience From 8 Years of ELBE SRF-Gun II

Arnold, A.; Freitag, M.; Justus, M.; Lehnert, U.; Lu, P.; Ma, S.; Michel, P.; Murcek, P.; Ryzhov, A.; Schaber, J.; Schneider, C.; Steinbrück, R.; Teichert, J.; Xiang, R.; Ciovati, G.; Kneisel, P.; Vennekate, J.

At the electron accelerator for beams with high brilliance and low emittance (ELBE), the second version of a superconducting radio-frequency (SRF) photoinjector was brought into operation in 2014. After a period of commissioning, a gradual transfer to routine operation took place in 2017, so that now more than 1800h of user beam are generated every year. Since the commission, a total of 24 cathodes (2 Cu, 12 Mg, 10 Cs2Te) have been used, without observing serious cavity degradation. The contribution summarizes commissioning and operational experience of the last 8 years of gun operation, with special emphasis on SRF properties but also on specialties such as dark current and multipacting that are directly linked to the integration of a normal conducting cathode into the SRF cavity.

Keywords: SRF; Gun; electron source; injector; ELBE; DALI

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  • Open Access Logo Invited lecture (Conferences)
    21st International Conference on Radio-Frequency Superconductivity (SRF 2023), 25.-30.06.2023, Michigan, USA

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Permalink: https://www.hzdr.de/publications/Publ-37334
Publ.-Id: 37334


Designing magnetocaloric materials for hydrogen liquefaction with light rare-earth Laves phases

Liu, W.; Gottschall, T.; Scheibel, F.; Bykov, E.; Fortunato, N.; Aubert, A.; Zhang, H.; Skokov, K.; Gutfleisch, O.

Magnetocaloric hydrogen liquefaction could be a ‘game-changer’ for liquid hydrogen industry. Although heavy rare-earth based magnetocaloric materials show strong magnetocaloric effects in the temperature range required by hydrogen liquefaction (77–20 K), the high resource criticality of the heavy rare-earth elements is a major obstacle for upscaling this emerging liquefaction technology. In contrast, the higher abundances of the light rare-earth elements make their alloys highly appealing for magnetocaloric hydrogen liquefaction. Via a mean-field approach, it is demonstrated that tuning the Curie temperature (TC) of an idealized light rare-earth based magnetocaloric material towards lower cryogenic temperatures leads to larger maximum magnetic and adiabatic temperature changes (ΔST and ΔTad). Especially in the vicinity of the condensation point of hydrogen (20 K), ΔST and ΔTad of the optimized light rare-earth based material are predicted to show significantly large values. Following the mean-field approach and taking the chemical and physical similarities of the light rare-earth elements into consideration, a method of designing light rare-earth intermetallic compounds for hydrogen liquefaction is used: tuning TC of a rare-earth alloy to approach 20 K by mixing light rare-earth elements with different de Gennes factors. By mixing Nd and Pr in Laves phase (Nd, Pr)Al2, and Pr and Ce in Laves phase (Pr, Ce)Al2, a fully light rare-earth intermetallic series with large magnetocaloric effects covering the temperature range required by hydrogen liquefaction is developed, demonstrating a competitive maximum effect compared to the heavy rare-earth compound DyAl.

Permalink: https://www.hzdr.de/publications/Publ-37332
Publ.-Id: 37332


Magnetic anisotropy, magnetoelastic coupling, and the magnetic phase diagram of Ni0.25Mn0.75TiO3

Elghandour, A.; Gries, L.; Singer, L.; Hoffmann, M.; Spachmann, S.; Uhlarz, M.; Dey, K.; Klingeler, R.

Thermodynamic and magnetic studies on high-quality single crystals are used to investigate the magnetic phase diagram and magnetostructural coupling in the mixed-spin system Ni0.25Mn0.75TiO3. Clear anomalies in the thermal expansion at the spin ordering and spin reorientation temperatures, TN and TR, evidence pronounced magnetoelastic effects. The magnetic entropy is released mainly above TN implying considerable short range magnetic order up to about 4 × TN . This is associated with a large regime of negative thermal expansion of the c axis. Both TN and TR exhibit the same sign of uniaxial pressure dependence, which is positive (negative) for pressure applied along the b (c) axis. The magnetic phase diagrams are constructed and the uniaxial pressure dependencies of the ordering phenomena are determined. For magnetic fields B II b axis, a sign change and splitting of anomalies implies further magnetic phases. In addition to short-range magnetic order well above TN, competing anisotropies yield a glasslike behavior as evidenced by a maximum in AC-χ (TSG ≃ 3.7 K) and quasilinear temperature dependence of cp. High-field magnetization up to 50 T demonstrates that in addition to antiferromagnetically ordered spins there are also only weakly coupled moments at 2 K with a sizable amount of about 15% of all Mn2+ spins present in the material. The observed changes in the pressure dependence and the magnetostrictive effects shed light on the recently observed flop of electric polarization from P II c to P II a [Phys. Rev. B 90, 144429 (2014)], in particular, suggesting that the magnetoelectric effect is not directly related to magnetostriction.

Permalink: https://www.hzdr.de/publications/Publ-37331
Publ.-Id: 37331


Berezinskii—Kosterlitz—Thouless correlations in copper-based quasi-2D spin systems

Opherden, D.; Bärtl, F.; Tepaske, M. S. J.; Landee, C. P.; Wosnitza, J.; Kühne, H.

We present an overview of selected copper-based quasi-2D square-lattice spin-1/2 materials with an easy-plane anisotropy, providing the possibility to study emergent Berezinskii-Kosterlitz-Thouless (BKT) correlations. In particular, in those materials with a comparatively small exchange coupling, the effective XY anisotropy of the low-temperature spin correlations can be controlled by an applied magnetic field, yielding a systematic evolution of the BKT correlations. In cases where the residual interlayer correlations are small enough, dynamical BKT correlations in the critical regime may be observed experimentally, whereas the completion of the genuine BKT transition is preempted by the onset of long-range order.

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  • Secondary publication expected from 01.07.2024

Permalink: https://www.hzdr.de/publications/Publ-37330
Publ.-Id: 37330


Elemental Dilution Effect on the Elastic Response due to a Quadrupolar Kondo Effect of the Non-Kramers System Y1-xPrxIr2Zn20

Hibino, R.; Yanagisawa, T.; Mikami, Y.; Hidaka, H.; Amitsuka, H.; Zherlitsyn, S.; Wosnitza, J.; Yamane, Y.; Onimaru, T.

We measured the elastic constants (C11 − C12)/2 and C44 of the non-Kramers system Y0.63Pr0.37Ir2Zn20 (Pr-37% system) by means of ultrasound to check how the single-site quadrupolar Kondo effect is modified by increasing the Pr concentration. The Curie-like softening of (C11 − C12)/2 of the present Pr-37% system on cooling from 5 to 1K can be reproduced by a multipolar susceptibility calculation based on the non-Kramers Γ3 doublet crystalline-electric-field ground state. Further, on cooling below 0.15 K, a temperature dependence proportional to √T was observed in (C11 − C12)/2. This behavior rather corresponds to the theoretical prediction of the quadrupolar Kondo “lattice” model, unlike that of the Pr-3.4% system, which shows a logarithmic temperature dependence based on the “single-site” quadrupolar Kondo theory. In addition, we discuss the possibility to form a vibronic state by the coupling between the low-energy phonons and the electric quadrupoles of the non-Kramers doublet in the Pr-37% system, since we found a low-energy ultrasonic dispersion in the temperature range between 0.15 and 1K.

  • Open Access Logo Journal of the Physical Society of Japan 92(2023), 074708
    DOI: 10.7566/JPSJ.92.074708
    arXiv: https://doi.org/10.48550/arXiv.2212.09714

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Permalink: https://www.hzdr.de/publications/Publ-37329
Publ.-Id: 37329


Na2Ga7: A Zintl–Wade Phase Related to “α-Tetragonal Boron”

Yu, C.-C.; Ormeci, A.; Veremchuk, I.; Feng, X.-J.; Prots, Y.; Krnel, M.; KožElj, P.; Schmidt, M.; Burkhardt, U.; BöHme, B.; Akselrud, L.; Baitinger, M.; Grin, Y.

Na2Ga7 crystallizes with the orthorhombic space group Pnma (no. 62; a = 14.8580(6) Å, b = 8.6766(6) Å, and c = 11.6105(5) Å; Z = 8) and constitutes a filled variant of the Li2B12Si2 structure type. The crystal structure consists of a network of icosahedral Ga12 units with 12 exohedral bonds and four-bonded Ga atoms in which the Na atoms occupy the channels and cavities. The atomic arrangement is consistent with the Zintl [(4b)Ga]− and Wade [(12b)Ga12]2– electron counting approach. The compound forms peritectically from Na7Ga13 and the melt at 501 °C and does not show a homogeneity range. The band structure calculations predict semiconducting behavior consistent with the electron balance [Na+]4[(Ga12)2–][Ga–]2. Magnetic susceptibility measurements show that Na2Ga7 is diamagnetic.

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Permalink: https://www.hzdr.de/publications/Publ-37328
Publ.-Id: 37328


Bi-sided facility location problems: an efficient algorithm for k-centre, k-median, and travelling salesman problems

Davoodi Monfared, M.; Rezaei, J.

This study introduces a general framework, called Bi-sided facility location, for a wide range of problems in the area of combined facility location and routing problems such as locating test centres and designing the network of supermarkets. It is based on a multi-objective optimisation model to enhance the service quality which the clients received, called client-side, and enhance the interconnection quality and eligibility among the centres, called center-side. Well-known problems such as k-median and k-centre for the client-side and the travelling salesman problem for the centre-side are taken into account in this paper. After discussing the complexity of this kind of combination, we propose a heuristic approximation algorithm to find approximation Pareto-optimal solutions for the problem. The algorithm is an efficient local search utilising geometric objects such as the Voronoi diagram and Delaunay triangulation as well as algorithms for computing approximation travelling salesman tour. In addition to the comprehensive theoretical analysis of the proposed models and algorithm, we apply the algorithm to different instances and benchmarks, and compare it with NSGA-II based on set coverage and spacing metrics. The results confirm the efficiency of the algorithm in terms of running time and providing a diverse set of efficient trade-off solutions.

Keywords: Facilities planning; local search; approximation; routing; connected facility location; Travelling Salesman Problem

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  • Secondary publication expected from 18.07.2024

Permalink: https://www.hzdr.de/publications/Publ-37327
Publ.-Id: 37327


Unveiling new quantum phases in the Shastry-Sutherland compound SrCu2(BO3)2 up to the saturation magnetic field

Nomura, T.; Corboz, P.; Miyata, A.; Zherlitsyn, S.; Ishii, Y.; Kohama, Y.; Matsuda, Y. H.; Ikeda, A.; Zhong, C.; Kageyama, H.; Mila, F.

Under magnetic fields, quantum magnets often undergo exotic phase transitions with various kinds of order. The discovery of a sequence of fractional magnetization plateaus in the Shastry-Sutherland compound SrCu2(BO3)2 has played a central role in the high-field research on quantummaterials, but so far this system could only be probed up to half the saturation value of the magnetization. Here, we report the first experimental and theoretical investigation of this compound up to the saturation magnetic field of 140 T and beyond. Using ultrasound and magnetostriction techniques combined with extensive tensor-network calculations (iPEPS), several spin-supersolid phases are revealed between the 1/2 plateau and saturation (1/1 plateau). Quite remarkably, the sound velocity of the 1/2 plateau exhibits a drastic decrease of -50%, related to the tetragonal-to-orthorhombic instability of the checkerboard-type magnon crystal. The unveiled nature of this paradigmatic quantum system is a new milestone for exploring exotic quantum states of matter emerging in extreme conditions.

Permalink: https://www.hzdr.de/publications/Publ-37326
Publ.-Id: 37326


Nanoelektronik für Immuntherapien

Nguyen Le, T. A.; Nieder, D.; Baraban, L.

Cancer is an extraordinarily diverse disease that affects our society globally; it hits people of all ages and genders. Because of its high mortality rate, it is responsible on average for one in six deaths, it is the second most common cause of death, according to the World Health Organization. In this article, published in 'Krebs im Focus, Die Wissenschaftszeitschrift des NCT/UCC Dresden', the importance of immune cancer phenotyping to make use of the recent advances in cancer immunotherapy, based on immune checkpoint inhibition and cross-linking of immune cells to target cancer cells, is outlined. The research landscape in the last few years has shown encouraging signs for nanoelectronics to be better represented in cancer research in near future. In particular, this approach can open new routes to perform a complex combinatorial analysis using tiny electronic chips and simultaneously screening multiple biochemical species thus facilitating the transition from conventional medicine to precision medicine in clinical oncology.

Keywords: Nanoelectronic; Biosensor; Cancer phenotyping

  • Open Access Logo Krebs im Focus (2023)

Permalink: https://www.hzdr.de/publications/Publ-37325
Publ.-Id: 37325


Role of alkaline metal in the rare-earth triangular antiferromagnet KYbO2

Grußler, F.; Hemmida, M.; Bachus, S.; Skourski, Y.; Krug Von Nidda, H.-A.; Gegenwart, P.; Tsirlin, A. A.

We report crystal structure and magnetic behavior of the triangular antiferromagnet KYbO2, the A-site substituted version of the quantum spin liquid candidate NaYbO2. The replacement of Na by K introduces an anisotropic tensile strain with 1.6% in-plane and 12.1% out-of-plane lattice expansion. Compared to NaYbO2, both Curie-Weiss temperature and saturation field are reduced by about 20% as the result of the increased Yb-O-Yb angles, whereas the g tensor of Yb3+ becomes isotropic with g = 3.08(3). Field-dependent magnetization shows the plateau at 1/2 of the saturated value and suggests the formation of the up-up-up-down field-induced order in KYbO2 in contrast to the more common 1/3 plateau with the up-up-down order that has been reported in the isostructural Yb3+ selenides.

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Permalink: https://www.hzdr.de/publications/Publ-37324
Publ.-Id: 37324


On the high-field characterization of magnetocaloric materials using pulsed magnetic fields

Salazar Mejia, C.; Niehoff, T.; Straßheim, M.; Bykov, E.; Skourski, Y.; Wosnitza, J.; Gottschall, T.

Magnetic refrigeration is a highly active field of research. The recent studies in materials and methods for hydrogen liquefaction and innovative techniques based on multicaloric materials have significantly expanded the scope of the field. For this reason, the proper characterization of materials is now more crucial than ever. This makes it necessary to determine the magnetocaloric and other physical properties under various stimuli such as magnetic fields and mechanical loads. In this work, we present an overview of the characterization techniques established at the Dresden High Magnetic Field Laboratory in recent years, which specializes in using pulsed magnetic fields. The short duration of magnetic-field pulses, lasting only some ten milliseconds, simplifies the process of ensuring adiabatic conditions for the determination of temperature changes, ΔTad. The possibility to measure in the temperature range from 10 to 400 K allows us to study magnetocaloric materials for both room-temperature applications and gas liquefaction. With magnetic-field strengths of up to 50 T, almost every first-order material can be transformed completely. The high field-change rates allow us to observe dynamic effects of phase transitions driven by nucleation and growth as well. We discuss the experimental challenges and advantages of the investigation method using pulsed magnetic fields. We summarize examples for some of the most important material classes including Gd, Laves phases, La–Fe–Si, Mn–Fe–P–Si, Heusler alloys and Fe–Rh. Further, we present the recent developments in simultaneous measurements of temperature change, strain, and magnetization, and introduce a technique to characterize multicaloric materials under applied magnetic field and uniaxial load. We conclude by demonstrating how the use of pulsed fields opens the door to new magnetic-refrigeration principles based on multicalorics and the ‘exploiting-hysteresis’ approach.

Permalink: https://www.hzdr.de/publications/Publ-37323
Publ.-Id: 37323


Random singlets in the s = 5/2 coupled frustrated cubic lattice Lu3Sb3Mn2O14

Lee, C.; Lee, S.; Kim, H.-S.; Kittaka, S.; Kohama, Y.; Sakakibara, T.; Lee, K. H.; van Tol, J.; Gorbunov, D.; Do, S.-H.; Yoon, S.; Berlie, A.; Choi, K.-Y.

We combine thermodynamic, electron spin resonance (ESR), and muon spin-relaxation (μSR) measurements with density functional theory (DFT) and classical Monte Carlo calculations toward understanding a disorderdriven behavior of the 3D coupled frustrated cubic lattice Lu3Sb3Mn2O14 with s = 5/2. The classical Monte Carlo calculations based on exchange interactions extracted from DFT predict that Lu3Sb3Mn2O14 undergoes a transition to magnetic ordering. In sharp contrast, our specific heat measurements evince a weak magnetic anomaly at 0.5 K while μSR detects neither long-range magnetic order nor spin freezing down to 0.3 K. For temperatures above 2 K, our ac susceptibility, magnetization, and specific heat data obey temperature-magnetic field scalings, indicative of the formation of 3D random singlets. The development of multiple ESR lines with decreasing temperature below 80 K supports the notion of inhomogeneous magnetism. Our results extend random-singlet physics to 3D frustrated classical magnets with a large spin number s = 5/2.

Permalink: https://www.hzdr.de/publications/Publ-37322
Publ.-Id: 37322


Neutron diffraction, muon-spin rotation, and high magnetic field investigation of the multiferroic antiferromagnetic quantum spin-chain system CuCrO4

Law, J.; Luetkens, H.; Pascua, G.; Hansen, T.; Glaum, R.; Wang, Z.; Wosnitza, J.; Kremer, R. K.

Multiferroic behavior in the linear-chain spin S = 1/2 compound CuCrO4 was proposed to appear due to competing nearest- and next-nearest-neighbor exchange interactions along the chain. Here, we report on our study of the long-range magnetic ordering using powder neutron diffraction and muon-spin rotation measurements. Consistently, both methods find incommensurate long-range antiferromagnetic ordering below 8.5(3) K. We determined the magnetic structure from neutron powder diffraction patterns based on the propagation vector τ = (0, 0, 0.546(1)). At 1.9 K, the magnetic moment of Cu2+ was refined to 0.48(2) μB. The Cu moments form a helicoidal spiral with an easy plane coinciding with the equatorial planes of the Jahn-Teller elongated CuO6 octahedra. Low-temperature high magnetic field measurements of the magnetization and the dielectric polarization show the multiferroic phase to extend up to ∼25 T, after which a new, yet unknown phase appears. Full saturation of the magnetic moment is expected to occur at fields much beyond 60 T.

Permalink: https://www.hzdr.de/publications/Publ-37321
Publ.-Id: 37321


Tetracene Crystals as Promising Anode Material for Alkali Metal Ion Batteries

Chepkasov, I.; Krasheninnikov, A.

Using first-principles calculations we study the energetics of alkali metal (AM) atom intercalation into bulk tetracene crystals. We show that, contrary to the adsorption of Li and Na atoms on isolated tetracene molecules, the intercalation of these and other (K, Rb, Cs) AM atoms into bulk tetracene crystals is energetically favorable (with respect to forming an infinite AM crystal) in a wide range of AM concentrations and that the intercalation en- ergy is noticeably lower than that for intercalation into graphite, a material used today in anodes of AM batteries. In case of Li, there is no swelling of the intercalated crystals, and for Na the increase in crystal volume is less than 10%, which makes crystalline tetracene attractive from the viewpoint of energy storage, as the capacity exceeds the theoretical capacity of graphite. We further assess diffusion barriers of AM atoms, which for Li and Na proved to be below 0.5 eV, indicating a high diffusivity of these atoms already at room temperature. We also study the effects of intercalation on the electronic properties of the system, and show that several bands can be filled upon inter- calation, so that the system exhibits semiconducting-metallic-semiconducting behavior when AM atom concentration increases. Our results shed light on the perspective of using AM atom intercalation into tetracene crystals for energy storage and tuning the electronic properties of this system.

Keywords: tetracene; alkali metal ions; intercalation; first-principles calculations

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  • Secondary publication expected from 16.06.2024

Permalink: https://www.hzdr.de/publications/Publ-37320
Publ.-Id: 37320


Reproducibility of inverse gas chromatography under infinite dilution: Results and interpretations of an interlaboratory study

Sygusch, J.; Dümpelmann, R.; Meyer, R.; Adamska, K.; Strzemiecka, B.; Enke, D.; Rudolph, M.; Brendlé, E.

Over the last years, inverse gas chromatography (IGC) proved to be a versatile and sensitive analytical technique for physicochemical properties. However, the comparability of results obtained by different users and devices remains a topic for debate. This is the first time, an interlaboratory study using different types of IGC instruments is reported. Eight organizations with different IGC devices defined a common lab measurement protocol to analyse two standard materials, silica and lactose. All data was collected in a standard result form and has been treated identically with the objective to identify experimentally observed differences and not potentially different data treatments. The calculated values of the dispersive surface energy vary quite significantly (silica: 22 mJ/m2 - 34 mJ/m2, lactose 37 mJ/m2 - 51 mJ/m2) and so do the ISP values and net retention volumes for both materials. This points towards significant and seemingly undiscovered differences in the operation of the instruments and the obtained underlying primary data, even under the premise of standard conditions. Variations are independent of the instrument type and uncertainties in flow rates or the injected quantities of probe molecules may be potential factors for the differences. This interlaboratory study demonstrates that the IGC is a very sensitive analytical tool, which detects minor changes, but it also shows that for a proper comparison, the measurement conditions have to be checked with great care. A publicly available standard protocol and material, for which this study can be seen as a starting point, is still needed to judge on the measurements and the resulting parameters more objectively.

Keywords: Inverse gas chromatography; surface energy; specific interaction parameter; silica; lactose

Permalink: https://www.hzdr.de/publications/Publ-37319
Publ.-Id: 37319


Ultrafine particle flotation in a concept flotation cell combining turbulent mixing zone and deep froth fractionation with a special focus on the property vector of particles

Sygusch, J.; Stefenelli, N.; Rudolph, M.

Froth flotation faces increasing challenges in separating particles as those become finer and more complex, thus reducing the efficiency of the separation process. A lab flotation apparatus has been designed with the idea of combining the advantages of agitator-type froth flotation for high turbulences and column flotation with a deep froth zone for a fractionating effect enabling also to study the effect of different particle property vectors. A model system consisting of ultrafine (< 10 μm) glass particles with differing morphology (spheres vs. fragments) and wettability state (hydrophilic vs. moderately hydrophobic vs. strongly hydrophobic) as the floatable and magnetite as the non-floatable fraction was used for flotation to study how the separation process is influenced by the ultrafine property vectors of shape and wettability. Within this newly designed apparatus the froth depth was varied to investigate the fractionating effect and how the different particle fractions are affected by it. Furthermore, to evaluate the new apparatus, flotation tests had been carried out in a benchmark mechanical flotation cell under comparable conditions. Our findings contribute to ultrafine flotation techniques and especially our understanding of the complex effect of particle shape in combination with the other property vectors.

Keywords: froth flotation; column flotation; particle separation; multidimensional separation; entrainment; ultrafine particles; wettability; particle morphology; particle shape

Permalink: https://www.hzdr.de/publications/Publ-37318
Publ.-Id: 37318


Uptake of Pu(IV) by hardened cement paste in the presence of gluconate at high and low ionic strengths

Stietz, J.; Amayri, S.; Häußler, V.; Prieur, D.; Reich, T.

The uptake of Pu(IV) by hardened cement paste (HCP) at degradation stage I was investigated in the absence and presence of gluconate (GLU). Furthermore, the influence of the ionic strength was examined by different background electrolytes. For low ionic strength (I = 0.3 M) artificial cement pore water (ACW, pH = 13) and for high ionic strength (I = 2.5 M) cement pore water based on the diluted caprock solution (ACW-VGL, pH = 12.5) were used. Sorption experiments were performed under Ar atmosphere using HCP in the binary system HCP / GLU ([GLU]0/M = 1×10-1 - 1×10-8) and the ternary system HCP / Pu(IV) / GLU ([239Pu(IV)]0/M = 1×10-8, [GLU]0/M = 1×10-2) with S/L of 0.1 – 50 g L-1 within a contact time of 72 h. GLU sorbs strongly on HCP, a saturation of the sorption sites of HCP with GLU was observed at [GLU] ≥ 1×10-4 M at S/L = 5 g L-1. The effects of the order of addition of the components Pu(IV) and GLU showed a low sorption of Pu(IV) to HCP, indicating strong kinetic effects. In the absence of GLU, quantitative uptake (S% = 99%) of Pu(IV) by HCP was observed. GLU had a significant effect on the sorption of Pu(IV) to HCP in both background electrolytes.
Powder samples from batch experiments were investigated by X-ray absorption spectroscopy to determine the structural parameters of the near-neighbour environment of sorbed Pu ([Pu(III)]0/M = 5×10-6) on HCP (S/L = 2.5 g L-1) in dependence of the ionic strength of the background electrolyte (ACW and ACW-VGL) and in presence of GLU ([GLU]0/M = 1×10 2). Pu LIII-edge X-ray absorption near-edge structure spectra confirm the presence of Pu(IV) as the dominant species on HCP. Plutonium was incorporated mainly into the calcium silicate hydrates phases (C-S-H) of HCP. Also, the ionic strength of the background electrolytes, as well as the presence of GLU do not influence the speciation of Pu on HCP during the degradation state I in cement-based repository.

Keywords: ionic strength; plutonium; ordinary Portland cement; gluconate; EXAFS; XANES

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Permalink: https://www.hzdr.de/publications/Publ-37317
Publ.-Id: 37317


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