Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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41444 Publications

Structure prediction of iron hydrides at high pressures with machine-learned interatomic potentials

Tahmasbi, H.; Ramakrishna, K.; Lokamani, M.; Bethkenhagen, M.; Cangi, A.

Understanding the composition of Earth's core and mantle is a major challenge in geoscience
and materials science. The core is primarily made of iron, but its density is known to be
slightly lower than pure iron. Hydrogen contributes to this density deficit, leading to
significant interest in the properties and structure of iron hydrides under high pressure.

Previous studies have shown that the dhcp phase of FeH remains stable at lower pressures (10-40 GPa)
but undergoes phase transitions to hcp and fcc phases at higher pressures.
This study focuses on a theoretical exploration of the potential energy surfaces (PESs) of FeH under
varying pressure conditions. The objective is to demonstrate the effectiveness of automated and systematic
methods for training and validating transferable machine-learned interatomic potential (ML-IAP) using global
optimization techniques. By utilizing this potential, which significantly reduce computational costs,
the phase diagram of the stoichiometric Fe-H system is analyzed across a range of pressures.

To achieve this, we utilize the PyFLAME code to construct a highly transferable ML-IAP.
With this accurate potential, the PESs of bulk FeH structures are systematically investigated
through global sampling using the minima hopping method. This comprehensive exploration enables the prediction
of stable and metastable iron hydrides from 0 to 100 GPa. Density functional theory calculations are conducted
to refine the predicted structures and evaluate their dynamical stability.
The findings of this study reveal a wide range of novel low-energy polymorphs of FeH at each
pressure level, alongside the recovery of well-known structures in the literature.

  • Open Access Logo Poster
    NHR Conference 2023, 18.-19.09.2023, Berlin, Germany

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Permalink: https://www.hzdr.de/publications/Publ-37698


Orientational mercury removal from aqueous solution using three-dimensionally structured CuxS nanocluster anchored attapulgite

Dai, G.; Huang, J.; Ding, W.; Qiu, L.; Zhang, W.; Gu, Q.; Wang, Z.; Hu, Z.; Quan, C.; Li, P.

Toxic mercury-containing wastewater emitted from mining and nonferrous metallurgy seriously threatens human health and aquatic ecosystem. Effective mercury removal interfered with other coexisting metal ions in wastewater poses major challenges, requiring simple and sustainable methods. In this work, a novel three-dimensional (3D) CuxS nanocluster-anchored attapulgite (ATP@CuxS) is tailored for orientational mercury adsorption from diluted mercury-containing wastewater. The prepared ATP@CuxS adsorbent exhibited an unparalleled Hg2+ adsorption capacity of 746.48 mg g-1 among ever-reported clay-based adsorbents. Mercury-containing wastewater with an initial concentration of 5 mg L-1, and solution pH of 6.5 was ~100% removed within 20 min, and no interference by coexisting anionic and cation ions was observed. In the determination of the adsorption mechanism, in-situ intercalation and vulcanization of Cu2+ on ATP base constructs nanoclusters shaped CuxS that provide abundant active sites for Hg2+ adsorption. The negatively charged ATP facilitates positive Cu2+ immobilization on its surface followed by inorganic sulfide generation. This interfacial electrical compatibility makes a compact and stable composite.
33 Hydrophilic ATP modulated the uniform dispersion performance of ATP@CuxS, and
34 the dense CuxS package contributed to easier sedimentation and recovery after Hg2+
35 adsorption in water. Furthermore, Hg2+ removal efficiency was maintained at 70% after
36 8 times repetitions, indicating a gentle feasibility as a mass-generated adsorbent. The
37 proposed interface engineering from the perspective of micro-interface electrical
38 compatibility creates an attractive and easily accessible system that combines efficiency,
39 capacity, selectivity, and reusability for orientational removing Hg2+ from wastewater.

Keywords: CuxS nanocluster; Attapulgite; Interface engineering; Mercury removal; Orientational removal; Feasibility evaluation

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  • Secondary publication expected from 26.01.2025

Permalink: https://www.hzdr.de/publications/Publ-37697


Nucleation of surface nanobubbles in electrochemistry: Analysis with nucleation theorem

Ma, Y.; Huang, M.; Mutschke, G.; Zhang, X.

The formation of single bubbles at nanoelectrodes during electrochemical reactions allows to accurately identify the critical nucleus for bubble formation. As demonstrated before, combining nanoelectrode experiments and an analysis approach based on classical nucleation theory (CNT) delivers useful insight into bubble nucleation. In this work we propose an alternative approach to analyze the critical nuclei by applying the nucleation theorem (NT), which is able to overcome the inherent shortcomings of CNT. The size of the critical nucleus can be calculated more accurately by fitting experimental data in a simple form of the NT. Simulating the local gas concentration using a finite element approach, and considering the effect of gas oversaturation on the interfacial tension and the real gas compressibility, we obtain a more realistic estimation of the critical nuclei morphology. With the NT-based analysis presented, we re-analyze the nucleation data reported before. The properties of the critical nuclei obtained here are roughly consistent with those obtained from the CNT-based approach. In addition, we confirm that the critical nucleus for bubble formation in high gas oversaturation is featured with a contact angle much larger than Young’s contact angle.

Keywords: nanobubble; critical nucleous; nucleation theorem; finite element simulation; contact angle

Permalink: https://www.hzdr.de/publications/Publ-37696


Defect evolution in GaN thin film heterogeneously integrated with CMOS-compatible Si(100) substrate by ion-cutting technology

Shi, H.; Yi, A.; Ding, J.; Liu, X.; Qin, Q.; Yi, J.; Hu, J.; Wang, M.; Cai, D.; Wang, J.; Xu, K.; Mu, F.; Suga, T.; Heller, R.; Wang, M.; Zhou, S.; Xu, W.; Huang, K.; You, T.; Ou, X.

Ion-cutting technology is an ingenious solution to the high-quality heterogeneous integration of GaN thin films with CMOS-compatible Si(100) substrate, which provides a platform to combine GaN-based optoelectronics, high-frequency and high-power electronics with digital signal processing, logic computation, and control of Si(100) CMOS. Previously, we reported the fabrication of 2-inch GaN film on SiO2/Si(100) substrate (GaNOI) by the ion-cutting technology. In this study, we further study the defect evolution in the transferred GaN films, which is needed to promote the practical applications of the GaNOI material platform.

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Permalink: https://www.hzdr.de/publications/Publ-37695


The Heterogeneity of the Sandy Facies of Opalinus Clay across Scales, from Seismic Surveys to Radionuclide Diffusion - an in-situ Test in the Swiss Rock Laboratory Mont Terri

Heberling, F.; Albers, H.; Beilecke, T.; Deissmann, G.; Fischer, C.; Furche, M.; Geckeis, H.; Hoyer, E.-M.; Joseph, C.; Liebscher, A.; van Loon, L.; Lüth, S.; Ma, B.; Metz, V.; Müller, K.; Nowak, U.; Quinto, F.; Rebscher, D.; Rühaak, W.; Schulte, F.; Steegborn, F.; Tietz, T.

Many countries consider clay rock formations as potential host rocks for high-level nuclear waste disposal. Clay rocks may exhibit heterogeneity on various scales, from the micro- to the facies-scale. In the Mont Terri rock laboratory, Switzerland, various experiments study properties and characteristics of the Jurassic Opalinus Clay, which is the target host rock for the Swiss nuclear waste repository but may also provide proxies for other considered clay rock formations. At Mont Terri, the Opalinus Clay mainly appears in a shaly and two sandy facies. So far, diffusion experiments at Mont Terri focussed on the relatively homogeneous shaly facies. The upper sandy facies (SF-OPA) exhibits a more pronounced internal – mineralogical and textural – heterogeneity. Clay rocks with comparable heterogeneity to SF-OPA may be present among the lower Cretaceous clay rocks of northern Germany, which are among the potential host rock candidates for a future German nuclear waste repository. Since 2020, seven institutions develop an in-situ diffusion experiment in SF-OPA, the so-called DR-D experiment, to explore the impact of rock heterogeneity on radionuclide diffusion in low permeability clay rocks.
So far, the DR-D experiment combined high-resolution seismic tomography, borehole logging, and detailed drill core analyses to characterize the heterogeneity of the selected SF-OPA area. The targeted rock zone exhibits a layer starting ca. 10 m below the gallery surface, which is characterized by relatively high seismic velocities. This layer is as well evident in the natural gamma- and the neutron backscattering logs. In the drill cores it stands out as whitish rock characterized by large concretions and traces of bioturbation in contrast to the dark layered clay-rock above and below with smaller concretions. Detailed analysis of seismic signals and drill-cores is still ongoing. In future, an in-situ diffusion test using various radioactive and non-radioactive tracers (e.g., HTO, 129I, 22Na) will be conducted targeting the evidently heterogeneous rock section 10 m below the gallery surface. The evolution of tracer concentrations in a synthetic porewater circulating in the diffusion interval will be monitored. A second seismic tomography survey is planned after the termination of the diffusion experiment. Finally, overcoring and post-mortem analysis of the rock affected by tracer diffusion will be used to determine the local variability of diffusion parameters.
In this contribution, we present the general concept, technical layout, and expected scientific impact of the DR-D experiment, as well as first results from field and related laboratory studies.

  • Contribution to proceedings
    18th international conference on the chemistry and migration behaviour of actinides and fission products in the geosphere, 24.-29.09.2023, Nantes, France
  • Poster
    18th international conference on the chemistry and migration behaviour of actinides and fission products in the geosphere, 24.-29.09.2023, Nantes, France, 24.-29.09.2023, Nantes, France

Permalink: https://www.hzdr.de/publications/Publ-37694


Data publication: Chelator Impact: Investigating the Pharmacokinetic Behavior of Copper-64 Labeled PD-L1 Radioligands

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

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

Involved research facilities

  • PET-Center

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Permalink: https://www.hzdr.de/publications/Publ-37693


Poly(benzimidazobenzophenanthroline)-Ladder-Type Two-Dimensional Conjugated Covalent Organic Framework for Fast Proton Storage

Wang, M.; Wang, G.; Naisa, C.; Fu, Y.; Manoj Gali, S.; Paasch, S.; Wang, M.; Wittkaemper, H.; Papp, C.; Brunner, E.; Zhou, S.; Beljonne, D.; Steinrück, H.-P.; Dong, R.; Feng, X.

Electrochemical proton storage plays an essential role in designing next-generation high-rate energy storage devices, e.g., aqueous batteries. Two-dimensional conjugated covalent organic frameworks (2D c-COFs) are promising electrode materials, but their competitive proton and metal-ion insertion mechanisms remain elusive, and proton storage in COFs is rarely explored. Here, we report a perinone-based poly(benzimidazobenzophenanthroline) (BBL)-ladder-type 2D c-COF for fast proton storage in both a mild aqueous Zn-ion electrolyte and strong acid. We unveil that the discharged C−O− groups exhibit largely reduced basicity due to the considerable π-delocalization in perinone, thus affording the 2D c-COF a unique affinity for protons with fast kinetics. As a consequence, the 2D c-COF electrode presents an outstanding rate capability of up to 200 A g−1 (over 2500 C), surpassing the state-of-the-art conjugated polymers, COFs, and metal–organic frameworks. Our work reports the first example of pure proton storage among COFs and highlights the great potential of BBL-ladder-type 2D conjugated polymers in future energy devices.

Permalink: https://www.hzdr.de/publications/Publ-37692


Preclinical evaluation of an ¹⁸F-labeled Nε-acryloyllysine piperazide for covalent targeting of transglutaminase 2

Wodtke, R.; Laube, M.; Hauser, S.; Meister, S.; Ludwig, F.-A.; Fischer, S.; Kopka, K.; Pietzsch, J.; Löser, R.

Background: Transglutaminase 2 (TGase 2) is a multifunctional protein and has a prominent role in various physiological and pathophysiological processes. In particular, its transamidase activity, which is rather latent under physiological conditions, gains importance in malignant cells and supports tumor development and progression. Thus, there is a great need of theranostic probes for targeting tumor-associated TGase 2, and targeted covalent inhibitors appear particularly attractive as vector molecules in this regard. Such an inhibitor, equipped with a radionuclide suitable for noninvasive imaging, would be supportive for answering the general question on the possibility for functional characterization of tumor-associated TGase 2 in vivo. For this purpose, the recently developed ¹⁸F-labeled Nε-acryloyllysine piperazide [¹⁸F]7b, which is a potent and selective irreversible inhibitor of TGase 2, was subject to a detailed radiopharmacological characterization herein, including ex vivo biodistribution, metabolism and tumor uptake.
Results: An alternative radiosynthesis of [¹⁸F]7b under basic conditions is presented, which demands less than 300 µg of the respective trimethylammonio precursor per synthesis and provides [¹⁸F]7b in good radiochemical yields (17±7%) and high (radio)chemical purities (≥99%). Ex vivo biodistribution in healthy mice at 5 and 60 min p.i. revealed no permanent enrichment of ¹⁸F-activity in tissues with the exception of the bone tissue. In vivo pretreatment with ketoconazole and in vitro murine liver microsome (MLM) studies complemented by UPLC-MS/MS analysis demonstrated that bone uptake originates from metabolically released [¹⁸F]fluoride. Further metabolic transformations of [¹⁸F]7b include mono-hydroxylation and glucuronidation. Based on blood sampling data and MLM experiments, pharmacokinetic parameters such as plasma and intrinsic clearance were derived, which substantiated the apparently rapid distribution of [¹⁸F]7b in and elimination from the organisms. A TGase 2-mediated uptake of [¹⁸F]7b in different tumor cell lines could not be proven. Moreover, evaluation of [¹⁸F]7b in melanoma tumor xenograft models based on A375-hS100A4 (TGase 2 +) and MeWo (TGase 2 -) cells by ex vivo biodistribution and PET imaging were not indicative for a TGase 2-specific targeting.
Conclusion:
[¹⁸F]7b is a valuable radiometric tool to study TGase 2 in vitro under various conditions. However, its suitability for targeting tumor-associated TGase 2 is strongly limited due its unfavorable pharmacokinetic properties including a pronounced metabolization. Consequently, from a radiochemical perspective [18F]7b requires structural modifications to overcome these limitations.

Keywords: radiofluorination; liver microsomes; biodistribution; PET imaging; plasma clearance; pharmacokinetics; radiometabolites; defluorination

Involved research facilities

  • PET-Center

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Permalink: https://www.hzdr.de/publications/Publ-37691


Uranium(VI) interactions with Pseudomonas sp. PS-0-L, V4-5-SB and T5-6-I

Kasko, J.; Li, X.; Müller, K.; Ge, Y.; Vettese, G. F.; Law, G. T. W.; Siitari-Kauppi, M.; Huittinen, N. M.; Raff, J.; Bomberg, M.; Herzig, M.

Pseudomonas sp. are indigenous inhabitants of ombrotrophic bogs which can survive in acidic, nutrient-poor environments with wide temperature fluctuations. Their interactions with contaminant radionuclides can influence radionuclide biogeochemistry in boreal environment. Here, uranium (U(VI)) bioassociation by Pseudomonas sp. PS-0-L, V4-5-SB and T5-6-I isolated from a boreal bog was studied by a combination of batch contact experiments, spectroscopy and microscopy. All strains removed U from the solution and the U bioassociation efficiency was affected by the nutrient source, incubation temperature, time and pH. Highest U bioassociation occurred in the strains PS-0-L (0.199 mg U/gBDW) and V4-5-SB (0.223 mg U/gBDW). Based on in-situ attenuated total reflection Fourier transformation infrared spectroscopy (ATR FT-IR) analyses, the most likely functional groups responsible for U binding were the cell surface carboxyl groups. In addition, transmission electron microscopy with energy dispersive X-ray spectroscopy (TEM/EDX) showed dense intra-cellular round- and needle-like U accumulations in the cytoplasm and near to the inner cell membrane. The presence of U with phosphorus was indicated in elemental mapping. Modelled data showed ≡SOOHx-1 and ≡SOCO2Hx-1 as the dominant surface sites, contributing to the negative cell surface charge. The U removal efficiency depended on the U(VI) speciation under different pH conditions. At pH 5, the main species reacting with bacterial cell surfaces was UO22+, while at pH 9 UO2(OH)2 and UO2(OH)3- dominated the reactions. Further, U bioassociation increased with increasing aqueous U(VI) concentrations. Our data suggests U bioassociation on 1) outer cell membrane/cell wall associated carboxyl groups (e.g., proteins), and 2) intracellular phosphate groups (e.g., phospholipids).

Keywords: bioassociation; biosorption; bioaccumulation; modelling; carboxyl group; phosphate group

Permalink: https://www.hzdr.de/publications/Publ-37690


Oppositely charged surfactants and nanoparticles at the air-water interface: Influence of surfactant to nanoparticle ratio

Eftekhari, M.; Schwarzenberger, K.; Karakashev, S. I.; Grozev, N. A.; Eckert, K.

Hypothesis: The interactions between oppositely charged nanoparticles and surfactants can significantly influence the interfacial properties of the system. Traditionally, in the study of such systems, the nanoparticle concentration is varied while the surfactant concentration is kept constant, or vice versa. However, we believe that a defined variation of both components' concentration is necessary to accurately assess their effects on the interfacial properties of the system. We argue that the effect of nanoparticle-surfactant complexes can only be properly evaluated by keeping the surfactant to nanoparticle ratio constant.

Experiments: Zeta potential, dynamic light scattering, high amplitude surface pressure and surface tension measurements are employed synergistically to characterize the interfacial properties of the nanoparticle-surfactant system. Interferometric experiments are performed to highlight the effect of surface concentration on the stability of thin liquid films.

Findings: The interfacial properties of surfactant/nanoparticle mixtures are primarily determined by the surfactant/nanoparticle ratio. Below a certain ratio, free surfactant molecules are removed from the solution by the formation of surfactant-nanoparticle complexes. Surprisingly, even though the concentration and hydrophobicity of these complexes do not seem to have a noticeable impact on the surface tension, they do significantly affect the rheological properties of the interface. Above this ratio, free surfactant monomers and nanoparticle-surfactant complexes coexist and can co-adsorb at the interface, changing both the interfacial tension and the interfacial rheology, and thus, for example, the foamability and foam stability of the system.

Keywords: Nanoparticle surfactant complexes; Surfactant to nanoparticle ratio; Surface pressure isotherm; Zeta potential; Film stability

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  • Secondary publication expected from 04.10.2024

Permalink: https://www.hzdr.de/publications/Publ-37689


Opportunities and challenges for spintronics

Adelmann, C.; Jenkins, A.; Pirro, P.; Schultheiß, K.; van Dijken, S.; Kruglyak, V.; Bortolotti, P.

Conventional electronics use the flow of electric charges and are based on standard semiconductors. Spintronic devices exploit the electrons’ spin to generate and control currents and to combine electric and magnetic signals. Today there is a strong effort worldwide to integrate spintronic devices with standard CMOS technology towards hybrid spin-CMOS chips, offering advantages in terms of power consumption, compactness, and speed. Recent results (from SAMSUNG [1], TSMC [2], etc.) confirm the merit of this approach.

Keywords: spintronics; magnonics

Permalink: https://www.hzdr.de/publications/Publ-37688


Research data management of laser-plasma science at HZDR

Schlenvoigt, H.-P.; Tippey, K. E.; Horn, W.; Bock, S.; Pape, D.; Knodel, O.; Kluge, T.; Irman, A.; Zeil, K.; Schramm, U.

The Draco laboratory at HZDR is a versatile, multi-arm and multi-target-area facility, consisting of several, independent subsystems. The lack of an overarching DAQ is balanced by interfaces of the subsystems and custom inter-linking agents. We present recent progress of implementing such software agents, connecting to the center’s electronic lab documentation system. First, manual logging of shot parameters and observations is lifted from spreadsheet software to a flexible web-app, writing to a database (DB). The laser-internal logging is exported to a DB and internal software triggering is forwarded to experiments. That provides a connection between laser-internal indexing and experiment-based indexing (another DB) and enables near-online data processing. The latter comprises file path logging and validation according to the shot’s acquisition settings for further analysis as well as basic on-shot analysis scripts, both enabling near-online visualization to better guide the course of experiments.
Likewise, parameters and results from simulations are logged to databases, enabling machine learning techniques and better computing resource management.
For a long-term, FAIR storage, the HELPMI project starts exploring the possibilities of openPMD and NeXus to ingest experimental data. That project shall serve as initiative for the global LPA community to find a data and metadata standard.

Keywords: data standard; metadata

Involved research facilities

  • HIBEF
  • ATHENA
  • Draco
  • Penelope
  • Open Access Logo Poster
    6th European Advanced Accelerator Concepts workshop, 18.-22.09.2023, La Biodola Bay, Isola d'Elba, Italy

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Permalink: https://www.hzdr.de/publications/Publ-37687


Synthese und Radiomarkierung von macropa-PSMA-Derivaten für die Tumorbildgebung mit Iod-123

Krönke, T.

Ziel: macropa-PSMA-Konjugate mit Albuminbinder zur zielgerichteten Alphatherapie mit 225Ac wurde innerhalb der Arbeitsgruppe bereits erfolgreich synthetisiert und in vitro und in vivo untersucht.[1,2] Die dabei eingeführte albuminbindende Einheit bietet die Grundlage zur Erarbeitung eines theranostischen Ansatzes indem, neben der Komplexierung des Alphaemitters 225Ac, die Bindung von Iod-123 als leicht zugängliches SPECT-Nuklid im gleichen Molekül ermöglicht wird. Vorteilhaft sind die milden Markierungsbedingungen sowie eine passende Halbwertszeit des Iodisotopes (t1/2 =13,2 h), welche die Bildgebung länger zirkulierender Substanzen ermöglicht.
Methoden: Die Synthese der peptidomimetischen Ausgangsverbindungen erfolgte angelehnt an die Vorarbeiten durch mehrstufige Peptidkupplungen und die Anbringung des Chelators mittels Cu-katalysierter Click-Reaktion. Anstelle der 4-(p-Iodphenyl)buttersäure wurde der entsprechende Zinnprecursor eingeführt, um die Verbindung durch eine elektrophile, aromatische Substitution mit 123I markieren zu können.

Keywords: macropa; Radiohybridkonjugate; Actinium-225; Iod-123; Alphatherapie

  • Master thesis
    TU Dresden - Fakultät Chemie und Lebensmittelchemie, 2023
    Mentor: PD Dr. Constantin Mamat
    72 Seiten

Permalink: https://www.hzdr.de/publications/Publ-37686


Synthese und Radiomarkierung von macropa-PSMA-Derivaten für die Tumorbildgebung mit Iod-123

Krönke, T.; Reissig, F.; Pietzsch, H.-J.; Kopka, K.; Mamat, C.

Ziel: macropa-PSMA-Konjugate mit Albuminbinder zur zielgerichteten Alphatherapie mit Actinium-225 wurde innerhalb der Arbeitsgruppe bereits erfolgreich synthetisiert und in vitro und in vivo untersucht. Die dabei eingeführte albuminbindende Einheit bietet die Grundlage zur Erarbeitung eines theranostischen Ansatzes indem, neben der Komplexierung des Alphaemitters Actinium-225, die Bindung von Iod-123 als leicht zugängliches SPECT-Nuklid im gleichen Molekül ermöglicht wird. Vorteilhaft sind die milden Markierungsbedingungen sowie eine passende Halbwertszeit des Iodisotopes (t1/2 =13,2 h), welche die Bildgebung länger zirkulierender Substanzen ermöglicht.
Methoden: Die Synthese der peptidomimetischen Ausgangsverbindungen erfolgte angelehnt an die Vorarbeiten durch mehrstufige Peptidkupplungen und die Anbringung des Chelators mittels Cu-katalysierter Click-Reaktion. Anstelle der 4-(p-Iodphenyl)buttersäure wurde der entsprechende Zinnprecursor eingeführt, um die Verbindung durch eine elektrophile, aromatische Substitution mit Iod-123 markieren zu können.
Ergebnisse: Durch die erfolgreiche Entwicklung einer Methode zur Iodierung der synthetisierten Zinnprecursoren mit hohen radiochemischen Ausbeuten konnten schließlich die einfach bzw. doppelt PSMA-gebundenen Verbindungen [123I]I-mcp-M-alb-PSMA und [123I]I-mcp-D-alb-PSMA hergestellt werden. Nach der Iodierung der Verbindungen wurde in vitro der Einfluss des 139La-Komplexes als auch der des unkomplexierten Chelators an der PSMA-positiven Zelllinie LNCaP untersucht.
Schlussfolgerungen: Die Einführung von Iod-123 in die bereits untersuchten Derivate mit stabilem Iod-127 ergab keine Änderungen der biologischen Ergebnisse. Damit ergibt sich der neue Aspekt des theranostischen Nutzens als hybrides Radiopharmakon mit einer weiteren Markierungsstelle in der Peripherie des eigentlichen Liganden.

Keywords: Alphatherapie; Actinium-225; Iod-123; Macropa; Radiohybridkonjugate

  • Lecture (Conference)
    29. Jahrestagung der Arbeitsgemeinschaft Radiochemie/Radiopharmazie, 28.-30.09.2023, Bad Salzuflen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37685


Detectors of SPM cantilever deflection based on field emission phenomenon

Gacka, E.; Kwoka, K.; Sierakowski, A.; Janus, P.; Hlawacek, G.; Gotszalk, T.

The most common deflection detection methods for micro-electromechanical systems (MEMS), like microcantilevers used in scanning probe microscopy, include optical methods based on optical beam deflection systems, piezoresistive or capacitive methods. This issue is still being pursued in order to develop a method with the highest possible deflection sensitivity. For this reason, attention is focused on exploiting the field emission phenomenon – the tunnelling of electrons through a potential barrier that occurs when the applied threshold voltage between electrodes is exceeded.
This work presents a method for microcantilever deflection detection based on field emission phenomenon – fig. 1a. As a result of cantilever deflection, the distance between the emitter tips (electrodes) was changed, resulting in a variation of the threshold voltage and field emission current. Nanotip field emitters were integrated into the microcantilevers using a focused electron and ion beam induced deposition (FEBID/FIBID) (fig. 1b). This one-step process allowed for the simplification of their fabrication technology. The effect of distance between electrodes and emitter shape on the emission enhancement factor was analysed. Preliminary usability tests of the sensor have been performed.
Acknowledgements: This work was supported by the National Science Centre, Poland PRELUDIUM-21 grant [“Nanometrology of field emission phenomena from electron beam deposited nanowires operating as nano- and picodeflection sensors – FEmet”, grant number 2022/45/N/ST7/03049]; and a short term scientific mission funded by the COST Action CA19140 (http://www.fit4nano.eu/).

Keywords: HIM; FIB; SPM; FIBID

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Related publications

  • Lecture (Conference)
    XII Workshop on Applications of Scanning Probe Microscopy – STM/AFM 2023, 29.11.-03.12.2023, Zakopane, Polen

Permalink: https://www.hzdr.de/publications/Publ-37683


The MultiMorph Model for industrial multiphase flows

Schlegel, F.

Introduction to the MultiMorph model developed at HZDR for numerical simulation of multiphase flows with morphology transition

  • Lecture (Conference)
    2023 HZDR Science Conference, 15.-16.11.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37679


From Multiphase Code Repository by HZDR for OpenFOAM Foundation Software towards a Helmholtz Energy Multiphase Platform?

Schlegel, F.

Open source software has become indispensable for science, in particular with respect to the FAIR principles it is a sufficient requirement. The full access to the source code and the transparency of the open source research software requires completely new concepts and business models between software providers and users, as well as the organisation of the community. This poses a challenge, but on the other side opens up space for new, creative solutions and a new perspectives. Within open source software there is an enormous potential for more effective research and collaboration, which so far has been used only rarely by research organisations.
A very successful open source software for engineering applications is the C++-library OpenFOAM, which is developed for solving non-linear partial differential equations. HZDR has set itself the goal to ensure sustainable software development for our research. The contribution will present the experiences and learnings of HZDR from working with open-source software, exemplary for OpenFOAM, and from an intensive commitment as an OpenFOAM community member and contributor to the OpenFOAM Foundation release. The developers of the HZDR Multiphase Addon for OpenFOAM rely intensively on the Helmholtz Cloud Services, which provide a unique opportunity to foster sustainable software developments and collaboration. Based on the successful development of the HZDR Multiphase Addon and the growing importance of Computational Fluid Dynamics for reactor safety research the Bundesministerium für Umwelt, Naturschutz, nukleare Sicherheit und Verbraucherschutz finances the OpenFOAM_RCS project, a continuously growing, collaborative platform for qualification of OpenFOAM for nuclear safety research. The OpenFOAM_RCS platform is based on the Helmholtz Cloud Services and coordinated by HZDR in close collaboration with OpenFOAM Foundation.
The idea of the presentation is to present our experiences and to stimulate discussions with the aim to develop the HZDR Multiphase Addon and the OpenFOAM_RCS project into a Helmholtz Energy Multiphase Platform.

  • Poster
    Helmholtz Energy Conference 2023, 12.-13.06.2023, Koblenz, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37678


Lecture 13: Multiphase Developments with OpenFOAM Foundation Software

Schlegel, F.

A introduction into the open-source CFD toolbox OpenFOAM and sustainable development using the Helmholtz Cloud services

  • Lecture (Conference)
    19th Multiphase Flow Conference and Short Course: Simulation, Experiment and Application, 19.-23.06.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37677


Lecture 10: A Morphology Adaptive Multifield Two-Fluid Model

Schlegel, F.

An introduction into the MultiMorph Model developed at HZDR for numerical simulation of multiphase flows with morphology transitions.

  • Lecture (Conference)
    19th Multiphase Flow Conference and Short Course: Simulation, Experiment and Application, 19.-23.06.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37676


A Performance Study of Local Outlier Detection Methods for Mineral Exploration with Geochemical Compositional Data

Puchhammer, P.; Kalubowila, C.; Braus, L.; Pospiech, S.; Sarala, P.; Filzmoser, P.

In exploration geochemistry, mineral deposits are typically characterised by local changes of the analysed chemical composition, where enrichment of the targeted elements is expected. Local changes can also be found with local outlier detection methods, which are multivariate methods for outlier identification that incorporate the spatial neighbourhood of the samples. It is essential that geochemical data are treated as compositional data, and the requirements for their treatment depend on the specific local outlier detection method. We demonstrate how prominent local outlier detection methods can be used for mineral exploration with geochemical data that vary in scale, in the sampling density, and in data quality. The methods are compared based on known mineralisations, and recommendations for their usefulness are provided.

Keywords: geochmistry; till; exploration; robust statistics; logratio transformation

Permalink: https://www.hzdr.de/publications/Publ-37675


Structural investigations of Au-Ni aerogels: morphology and element distribution

Kresse, J.; Georgi, M.; Hübner, R.; Eychmüller, A.

The physical properties of nanomaterials are determined by their structural features, making accurate structural control indispensable. This carries over to future applications. In the case of metal aerogels, highly porous networks of aggregated metal nanoparticles, such precise tuning is still largely pending. Although recent improvements in controlling synthesis parameters like electrolytes, reductants, or mechanical stirring, the focus has always been on one particular morphology at a time. Meanwhile, complex factors, such as morphology and element distributions, are studied rather sparsely. We demonstrate the capabilities of precise morphology design by deploying Au-Ni, a novel element combination for metal aerogels in itself, as a model system to combine common aerogel morphologies under one system for the first time. Au-Ni aerogels were synthesized via modified one- and two-step gelation, partially combined with galvanic replacement, to obtain aerogels with alloyed, heterostructural (novel metal aerogel structure of interconnected nanoparticles and nanochains), and hollow spherical building blocks. These differences in morphology are directly reflected in the physisorption behavior, linking the isotherm shape and pore size distribution to the structural features of the aerogels, including a broad-ranging specific surface area (35-65 m2 g-1). The aerogels were optimized regarding metal concentration, destabilization, and composition, revealing some delicate structural trends regarding the ligament size and hollow sphere character. Hence, this work significantly improves the structural tailoring of metal aerogels and possible up-scaling. Lastly, preliminary ethanol oxidation tests demonstrated that morphology design extends to the catalytic performance. All in all, this work emphasizes the strengths of morphology design to obtain optimal structures, properties, and (performances) for any material application.

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Permalink: https://www.hzdr.de/publications/Publ-37674


Physics-Informed Machine Learning for Addressing Challenges in Static and Time-Dependent Density Functional Theory

Shah, K.; Cangi, A.

In this talk, we explore the potential of Physics-Informed Machine Learning (ML) in addressing
key computational tasks in both static and time-dependent Density Functional Theory (DFT
and TDDFT). The talk will focus on two projects that employ advanced ML techniques,
specifically Physics-Informed Neural Networks (PINNs) and Fourier Neural Operators (FNOs),
to tackle these complex tasks.
In the first part of the presentation, we examine the use of PINNs and FNOs in addressing the
intricate density-to-potential inversion problem in static DFT. By employing these methods as
alternatives to conventional inversion schemes, we demonstrate enhancements in predictive
transferability and speed. We highlight the applications to exactly solvable models, such as
soft-Coulomb systems, illustrating their potential as accurate and rapid data-driven surrogate
models.
In the second part of the talk, we discuss the application of PINNs to accelerate TDDFT
calculations. By incorporating the fundamental physical constraints of the Time-Dependent
Kohn-Sham equations directly into the learning process, PINNs offer a unique way to fuse the
power of deep learning with the nuances of TDDFT. We demonstrate the performance and
generalisability of PINN solvers on the time evolution of model systems across varying system
parameters, domains, and energy states.
By integrating physics and machine learning, these projects shed light on promising new
directions for addressing challenges in DFT and TDDFT. The methods developed here have
the potential to accelerate (TD)DFT workflows, enabling the simulation of large-scale
calculations of electron dynamics in matter exposed to strong electromagnetic fields, high
temperatures, and pressures.

  • Lecture (Conference)
    NHR Conference ’23, 18.-19.09.2023, Berlin, Germany
  • Lecture (Conference)
    March Meeting 2024, 03.-08.03.2024, Minneapolis, Minnesota, USA
  • Lecture (Conference)
    87th Annual Conference of the DPG and DPG Spring Meeting, 17.-22.03.2024, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37673


HELPMI: HElmholtz Laser-Plasma Metadata Initiative

Bagnoud, V.; Bussmann, M.; Debus, A.; Hornung, J.; Kaluza, M.; Kessler, A.; Pöschel, F.; Schlenvoigt, H.-P.; Schramm, U.; Eisenbarth, U.

HELPMI is a 2-year project, subsidized by the Helmholtz Metadata Collaboration, conducted by GSI, HI Jena and HZDR (lead). The aim is to start the development of a F.A.I.R. data standard for experimental data of the entire laser-plasma (LPA) community. Such standard does not yet exist. It will facilitate management and analysis of usually quite heterogeneous experimental data and logs by rich and machine-actionable metadata, allowing automated processing of broad and long data sets. To date, the LPA community is widely using openPMD, an open meta-standard, well-established for simulations. NeXus is a similarly hierarchical and extensible standard for various experimental methods of the Photon and Neutron science community. Within HELPMI, we plan to adopt NeXus for LPA experimental data and simultaneously to make openPMD and its API extensible for custom hierarchies like NeXus. Thereby we can achieve interoperability of the standards, circumventing the need for another standard. Alongside we will start developing a glossary of LPA experimental terms in order to achieve re-usability. The glossary shall be community-driven and technically open, extensible and implementation-independent.

Keywords: data standard; metadata; data management

Involved research facilities

  • HIBEF
  • ATHENA
  • Draco
  • Penelope
  • Open Access Logo Lecture (Conference) (Online presentation)
    HMC Conference 2023, 10.-12.10.2023, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37672


Modified Diglycolamide Resin: Characterization and Potential Application for Rare Earth Element Recovery

Romero, J.; Tabelin, C. B.; Park, I.; Alorro, R. D.; Zoleta, J.; Silva, L. C.; Arima, T.; Igarashi, T.; Mhandu, T.; Ito, M.; Happel, S.; Hiroyoshi, N.

Rare earth elements (REEs) are crucial for green energy applications due to their unique properties, but their extraction poses sustainability challenges because the global supply of REEs is concentrated in a few countries, particularly China, which produces 70% of the world’s REEs. To address this, the study investigated TK221, a modified extraction chromatographic resin featuring diglycolamide (DGA) and carbamoyl methyl phosphine oxide (CMPO), as a promising adsorbent for REE recovery. The elemental composition and functional groups of DGA and CMPO on the polystyrene-divinylbenzene (PS-DVB) support of TK221 were confirmed using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). The adsorption kinetics of neodymium (Nd), yttrium (Y), cerium (Ce), and erbium (Er) followed the pseudo-second-order kinetic model and Langmuir isotherm, indicating monolayer chemisorption. Furthermore, iron (Fe) adsorption reached apparent equilibrium after 360 min, with consistent Fe adsorption observed at both 360 min and 1440 min. The inclusion of Fe in the study is due to its common presence as an impurity in most REE leachate solutions. The Fe adsorption isotherm results are better fitted with the Langmuir isotherm, implying chemisorption. Maximum adsorption capacities (qmax) of the resin were determined as follows: Nd (45.3 mg/g), Ce (43.1 mg/g), Er (35.1 mg/g), Y (15.6 mg/g), and Fe (12.3 mg/g). ATR-FTIR analysis after adsorption suggested that both C=O and P=O bands shifted from 1679 cm−1 to 1618 cm−1 and 1107 cm−1 to 1142 cm−1 for Y, and from 1679 cm−1 to 1607 cm−1 and 1107 cm−1 to 1135 cm−1 for Ce, implying possible coordination with REEs. These results suggest that TK221 has a huge potential as an alternative adsorbent for REE recovery, thus contributing to sustainable REE supply diversification.

Keywords: RARE EARTH ELEMENTS; EXTRACTION CHROMATOGRAPHY; ION-EXCHANGE RESIN; ADSORPTION; CRITICAL METALS

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Permalink: https://www.hzdr.de/publications/Publ-37671


Failure of load-bearing dyke networks as a trigger for volcanic edifice collapse

Thiele, S. T.; Cruden, A. R.; Micklethwaite, S.

Most large ocean-island volcanoes are gravitationally unstable. Some deform slowly, forming long-lived slumps, while others collapse and generate potentially dangerous debris avalanches. Here we investigate the effect of pervasive dyke networks on edifice instability, using data from La Palma, Spain. Like fibre-reinforced composites, where rigid layers are embedded in a compliant matrix, we find that dykes experience higher stress than surrounding host rocks. If the ratio of dyke to host stiffness is larger than the corresponding strength ratio, the dyke network will fail first, causing a rapid stress redistribution and possibly triggering edifice collapse. Fibre bundle models of a weak layer crosscut by dykes suggest this can occur with less seismicity or deformation than models without dykes. The models also suggest that dyke network strength could determine the potential for rapid collapse rather than gradual slump-type deformation. We conclude that dyke networks should be considered when assessing volcanic edifice stability.

Keywords: volcanic island; landslide; composite material; geohazards

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Permalink: https://www.hzdr.de/publications/Publ-37670


Curvilinear Antiferromagnetic Spin Chains: Interplay Between Geometry And External Magnetic Field

Borysenko, Y.; Sheka, D.; Yershov, K.; Faßbender, J.; van den Brink, J.; Makarov, D.; Pylypovskyi, O.

Antiferromagnetically ordered (AFM) spin chains arranged along space curves represent a useful playground to study various possibilities of altering the sample’s magnetic response by its geometry modification. The influence of curvature (κ) and torsion (τ) is characterized by effective magnetic interactions, namely anisotropic and Dzyaloshinskii–Moriya-like, which originate from exchange, dipolar interaction and intrinsic anisotropy [1, 2]. The strength of these interactions depends on κ and τ, determining the ground state and spin dynamics of such systems [2, 3].

Here, we investigate theoretically the interplay between geometrical and magnetic field effects in intrinsically achiral anisotropic spin chains shaped as rings (constant κ, no torsion) and helices (constant κ, τ) exposed to uniform static and rotating magnetic fields. Exposed to static magnetic field, bulk AFMs possess a high-field spin-flop state, characterized by reorientation of the order parameter. In contrast to the spin-flop phase for the model of a bulk easy-axis AFM, in ring-shaped spin chains the spin-flop state comprises two topologically different ground states depending on κ. We attribute them to the influence of curvature-induced Dzyaloshinskii–Moriya interaction, as well as the spin-flop transition being of first or second order depending on the ring curvature and the presence of an intermediate canted state for large κ [4]. In the helix-shaped spin chain, a rotating magnetic field induces domain wall propagation with velocity, which is proportional to the field frequency. The relation between the external field and geometrical parameters determines two motion modes: oscillating one and rigid motion with a constant velocity. Curvature and torsion strongly influence domain wall velocity and stability conditions of the rigid motion mode.

Keywords: antiferromagnetism; curvilinear antiferromagnets

  • Lecture (Conference)
    IEEE NAP 2023, 10.-15.09.2023, Bratislava, Solvakia

Permalink: https://www.hzdr.de/publications/Publ-37669


X-ray absorption spectroscopy to identify radionuclide sequestration processes at solid-water interfaces: Sorption complexes, clusters and solid-solutions under reducing conditions

Scheinost, A.

Vorlesung im Rahmen der KRIMI Winter School an der TU Berlin

Keywords: EXAFS; ROBL; Nuclear waste

Involved research facilities

Related publications

  • Invited lecture (Conferences)
    KRIMI Winter School, 09.-13.10.2023, Berlin, Germany

Permalink: https://www.hzdr.de/publications/Publ-37668


Modellierung des Stofftransportes in einer geneigten Kolonne mit dem Ansatz der hydrodynamischen Analogien

Ehlert, T.; Mamedov, T.; Schubert, M.; Kenig, E. Y.

Modellierung des Stofftransportes in einer geneigten Kolonne mit dem Ansatz der hydrodynamischen Analogien

  • Poster
    Jahrestreffen der ProcessNet Fachgruppen Fluidverfahrenstechnik und Hochdruckverfahrenstechnik, 02.-03.05.2022, Frankfurt am Main, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37667


Charakterisierung des Einflusses neigungsinduzierter Strömungsformen mit dem Ansatz der hydrodynamsichen Analogie

Ehlert, T.; Mamedov, T.; Schubert, M.; Kenig, E. Y.

Charakterisierung des Einflusses neigungsinduzierter Strömungsformen mit dem Ansatz der hydrodynamsichen Analogie

  • Poster
    Jahrestreffen der DECHEMA-Fachgruppen Fluidverfahrenstechnik und Adsorption, 21.-23.03.2023, Frankfurt, Germany

Permalink: https://www.hzdr.de/publications/Publ-37666


Friend or Foe? Microbial impact of Calcigel bentonite on metal materials used for nuclear waste repository

Wei, T.-S.; Sushko, V.; Matschiavelli, N.; Kluge, S.; Cherkouk, A.

Multi-barrier concept is a favorable option to store high-level nuclear waste (HLW) in a deep geological repository. Bentonites are processed clay materials that are considered as a geotechnical barrier for metal containers storing HLW. To understand the impact of indigenous microorganisms from bentonites on these metal materials, anaerobic microcosms incubating Calcigel bentonite, synthetic Opalinus clay (OPA) porewater, lactate (one of the organic acids in natural OPA porewater) or H2 gas (product from anaerobic metal corrosion) with or without cast iron metal plates were conducted for up to 9 months in triplicates for each condition and time point (sampling every 3 months).

The amplicon sequencing targeting V4 region of 16S rRNA genes showed that microbial communities of raw Calcigel bentonites mainly comprised phyla Acidobacteria, Actinobacteria, Chloroflexi, Firmicutes, Proteobacteria and Methylomirabilota. In the microcosms with lactate, enrichment of Bacillaceae (Firmicutes) and uncultured MB-A2-108 (Actinobacteriota) were observed; whereas in the presence of both lactate and cast iron, genera of Firmicutes, namely Desulfotomaculum, Desulfitobacterium and Desulfallas-Sporotomaculum, were highly enriched (relative abundance ranged from 60% to 95%) associating with large decrease in sulfate and lactate concentration. These bacteria appeared to be driven by H2 gas generated from metal corrosion. Moreover, SEM-EDX analyses showed that the metal surface was corroded and covered by a carbonate passivation layer. In this layer, FeS appeared to be formed, further suggesting the influence on cast iron corrosion and formation of secondary minerals induced by sulfate-reducing bacteria.

On the other hand, we supplied N2 gas mixed with H2 and CO2 (80:10:10) to stimulate growth of H2-oxidizing sulfate reducers. GC analyses showed that in the microcosms without cast iron, the content of H2 gas in the headspace decreased accompanying with decrease in sulfate concentration (measured via IC). However, in the microcosms with cast iron we noted large accumulation of H2 gas (~ 5 times more than initial value) and greater decrease in sulfate concentration. Similarly, surface corrosion was visible by SEM-EDX, and thre carbonate passivation layer with possible FeS precipitates was formed on the metal surface but in a shorter timeframe (3 months). Hence, we speculated that certain autotrophic H2-oxidizing sulfate reducers also corroded cast iron metal, and their taxonomy and mechanisms will be identified using metagenomic approaches.

Altogether we concluded that microbial communities in Calcigel bentonites lead to microbially induced corrosion for cast iron under certain conditions, yet interestingly, the formation of passivation layer enhances the resistance for further metal corrosion. The actual impact of indigenous microorganisms in different bentonites, either disadvantageous or beneficial, on metal containers for HLW requires comprehensive investigations.

Keywords: Bentonite; MIC; Corrosion; Nuclear waste repository; Sulfate-reducing bacteria; Cast iron

  • Open Access Logo Lecture (Conference)
    2nd Joint Symposium of the International Societies for Environmental Biogeochemistry & Subsurface Microbiology 2023, 22.-28.10.2023, Banff, Canada
    DOI: 10.3897/aca.6.e108081

Permalink: https://www.hzdr.de/publications/Publ-37665


Euler-Euler simulation of multi-regime two-phase flow with thin liquid films

Porombka, P.; Boden, S.; Schlottke, J.

Euler-Euler simulation of multi-regime two-phase flow with thin liquid films

Keywords: CFD; Euler-Euler two-fluid model; horizontal annular flow; liquid film; multi-regime modelling

Involved research facilities

  • TOPFLOW Facility
  • Poster
    19th Multiphase Flow Conference and Workshop, 19.-23.06.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37664


High field suppression of bremsstrahlung emission in high-intensity laser-plasma interactions

Habibi, M.; Arefiev, A.; Toncian, T.

The interaction of high-intensity lasers with plasma is predicted to produce extreme quasi-static magnetic fields with magnitudes approaching Megatesla (MT) levels. In relativistically transparent plasmas, these fields can enhance direct laser acceleration and allow efficient gamma-ray emission by accelerated electrons. However, due to the so-called magnetic suppression effect, the magnetic field can also affect radiating electron trajectories and thus reduce the emission probability of the bremsstrahlung. This is the first study to examine the bremsstrahlung suppression mechanism in the context of high-intensity laser-plasma interactions. Our paper describes a new module that integrates the suppression effect into the standard bremsstrahlung module of the EPOCH particle-in-cell code by considering the impact of magnetic fields and extending the analysis to electric fields. We also investigate this suppressing mechanism's effect on the emitting electron's dynamics. Our findings show that this mechanism not only suppresses low-energy emissions but also has an impact on the dynamics of the radiating electrons.

Keywords: Bremsstrahlung emission; High field suppression; Relativistic transparency; High-intensity laser-plasma interaction

Involved research facilities

  • HIBEF

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Permalink: https://www.hzdr.de/publications/Publ-37663


Experimental analysis of ship motion effects on the performance of an absorption column equipped with structured packings

Mamedov, T.; Schleicher, E.; Schubert, M.; Ehlert, T.; Kenig, E. Y.; Hampel, U.

In the upstream sector of the modern offshore industry, mainly packed columns are used for gas purification purposes, such as the removal of CO2, SOx, NOx, and other impurities. Offshore conditions are known for their harsh environment conditions that pose extra challenges for stable process operations and can lead to inefficient separation. To make use of the newly explored offshore energy resources, floating vessels, namely, Floating Production Storage and Offloading (FPSO) units, are currently gaining dominance due to their technological and economic advantages over conventional offshore platforms. These floating vessels with their unique design can be operated in deeper locations by means of advanced technologies, i.e. mooring system and remote control mechanisms. Despite aforementioned facts, the impact of sea states and strong winds on the floating production systems cannot be fully suppressed, and these conditions affect the performance of onboard packed columns. To have a highly efficient separation process, the interfacial mass transfer area between the gas and liquid phases in packed columns must be sufficiently large, and for this reason, a uniform distribution of the phases in characteristic packing channels is required. However, realizing uniform flow distribution in the packings becomes more difficult during ship motions. When considering the geometric arrangement of column internals, structured packings are likely to have relatively better performance than random packings under these circumstances. Nevertheless, it is still unclear to what extent the flow distribution deviates from its ideal pathway under motion conditions and how this deviation degrades the separation performance.
In this study, most predominant sea conditions are considered to experimentally analyze the effect of ship motions on the mass transfer efficiency of packed columns. Therefore, air dehumidification with triethylene glycol (TEG) desiccant is chosen as an example of an absorption process in a structured packing column. To simulate typical motion conditions, an absorption column (DN150) equipped with Mellapak 250Y structured packings is placed on the mobile platform of a hexapod robot that mimics the six-degree-of-freedom ship motion. The mass transfer performance of the absorption column in the stationary upright position is first investigated by measuring the inlet and outlet humidity of the gas phase, and then the experimental results in static and dynamic inclination positions are compared to evaluate the relative deterioration of the efficiency. Furthermore, the impact of operating conditions, such as gas factor, liquid load, and TEG concentration, is explored.

  • Poster
    Jahrestreffen der DECHEMA-Fachgruppen Fluidverfahrenstechnik und Adsorption, 21.-23.03.2023, Frankfurt, Germany

Permalink: https://www.hzdr.de/publications/Publ-37662


(Radio)metal interaction with selected biosystems - from nuclear waste repositories to the food chain

Raff, J.

The investigation of the interaction of radionuclides with biosystems plays an important role not only in repository research but also in radioecology. The obtained knowledge expands the basic understanding of the behavior of radionuclides in nature on the one hand and opens up possibilities for the industrial use of the processes on the other hand. The lecture will give a general overview of the research work in biogeochemistry and its application potential.

Keywords: radionuclides; repository research; radio ecology; biosystems

Involved research facilities

Related publications

  • Lecture (others)
    Institutsseminar, Department of Nuclear Chemistry, Czech Technical University, 05.10.2023, Prag, Tschechien

Permalink: https://www.hzdr.de/publications/Publ-37661


Understanding warm dense matter: from ab initio simulations to experiments

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] to get
new insights into the behavior of WDM. Moreover, I will show how switching to the imaginary-
time representation allows us to significantly improve the interpretation of X-ray Thomson
scattering (XRTS) experiments, which are a key diagnostic for WDM [3,4,5]. Specifically, I will show how new
PIMC capabilities will allow to give us novel insights into electronic correlations in warm dense
quantum plasmas, leading to unprecedented agreement between experiments [6] and theory.

[1] M. Bonitz et al., Physics of Plasmas 27, 042710 (2020)
[2] M. Böhme et al., Physical Review Letters 129, 066402 (2022)
[3] S. Glenzer and R. Redmer, Reviews of Modern Physics 81, 1625 (2009)
[4] T. Dornheim et al., Nature Communications 13, 7911 (2022)
[5] T. Dornheim et al., arXiv:2305.15305 (submitted)
[6] T. Döppner et al., Nature 618, 270-275 (2023)

  • Lecture (Conference)
    Big data and analytical methods for complex systems, 19.10.2023, Wroclaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-37660


Characterisation of a high granularity multi-channel prompt γ-ray detection system prototype for proton range verification based on the PETsys TOFPET2 ASIC

Novgorodova, O.; Glatte, A.; Hentges, R.; Kögler, T.; Lutz, B.; Römer, K.; Teichmann, T.; Weinberger, D.; Straessner, A.

Proton therapy requires range verification in order to exploit its full potential. One of the most promising approaches is to monitor prompt gamma-rays produced by nuclear interactions of the therapeutic particles in the patient tissues. A detector with a wide energy range from 100 keV to 15 MeV and excellent time resolution is required to achieve millimetric precision in proton range. During patient treatment, the detector count rates are usually above 10⁶ s⁻¹ and the fraction of pile-up events is very high for commonly used fast inorganic scintillators. We are investigating a full acceptance approach with increased granularity in order to reduce the size of the scintillators and consequently the count rate per channel. Stacking the scintillators in matrices requires suitable multi-channel photo-multipliers and a fitting acquisition system. Here, we present two geometries of CeBr3 crystals 5 × 5 × 20 mm³ and 10 × 10 × 30 mm³, together with modern silicon photo-multipliers (SiPM) adapted to work with the PETsys TOFPET2 ASIC. The TOFPET2 ASIC was developed for Time-of-Flight Positron Emission Tomography (TOF-PET) applications. Here we show its potential for higher gamma-ray energies and future hybrid imaging. First results of energy resolution of 6.1 % - 7.8 % are achieved at 3.42 MeV using a ²⁴¹Am⁹Be source. The time resolution was found to be below 100 ps and studies of the count rates and the dead time of the full system were performed. Different SiPM models are analysed for their impact on the coincidence time resolution.

Keywords: Proton therapy; range verification; prompt gamma-rays; gamma-ray detectors; PETsys TOFPET2 ASIC; silicon photomultiplier

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Permalink: https://www.hzdr.de/publications/Publ-37659


Forschung für den Rückbau von Kernkraftwerken: Das Projekt KOBEKA

Hampel, U.

Während der Beprobung der Betonstrukturen des Reaktorgebäudes im Kernkraftwerk Stade wurden tief eingedrungene Kontaminationen im unteren Teil des Reaktorsicherheitsbehälters, der so genannten Betonkalotte, vorgefunden. Diese waren durch Primärkreiswasser aus verschiedenen Systemen während des Anlagenbetriebes eingetragen worden. Das Durchdringen der wasserabweisenden Dekontaminationsbeschichtung und die weitere Ausbreitung entlang von Arbeitsfugen hatten zu großräumiger Kontamination in der Größenordnung des bis zu 100-fachen der Freigabewerte geführt. Durch fehlende Detailkenntnisse zur Kontaminationsverteilung gestaltete sich der Rückbau erheblich zeit- und kostenaufwändiger als ursprünglich veranschlagt. Es ist davon auszugehen, dass dieses Problem andere Kernkraftwerke in Deutschland und weltweit betrifft.
Die Beprobung des Betons mittels Kernbohrungen ist durch erschwerte Zugänglichkeit des Beprobungsortes, baustatische Randbedingungen und Kosten eingeschränkt. Eine Alternative zu Kernbohrungen sind Bohrungen ins Volle. Wegen der schlankeren Bohrlöcher können deutlich mehr Bohrungen gesetzt werden, ohne die strukturelle Integrität des Reaktorgebäudes in unannehmbarem Maße zu schwächen. Allerdings fehlt es dann an Bohrkernen für eine Analytik. Das Vorhaben KOBEKA (gefördert durch das BMBF im Rahmen des Förderkonzeptes „FORKA - Forschung für den Rückbau kerntechnischer Anlagen“) beschäftigt sich daher mit der Entwicklung innovativer Messtechnik zur Beprobung und in-situ Messung in solchen schlanken Bohrlöchern. Entwickelt werden Technologien zur Detektion von Kontaminationen und zur Bestimmung des Nuklidvektors. Weiterhin sollen Feuchte und Porosität der Betonmatrix sowie die Präsenz von Borverbindungen ermittelt werden. Die Kenntnis der Porosität dient der Bestimmung der Lage von Arbeitsfugen, die Kenntnis des Feuchte- und Borgehalts geben Evidenz über eingedrungenes Primärkreiswasser. Zusätzlich ist die hydraulische Permeabilität zwischen verschiedenen Bohrungen von Interesse, um mögliche Transportwege über Arbeitsfugen zu identifizieren und damit die Beprobungsplanung zu unterstützen. Ebenfalls werden Werkzeuge zur Kartierung und elektronischen Dokumentation der Befunde entwickelt.

Keywords: Rückbau von Kernkraftwerken

Involved research facilities

  • TOPFLOW Facility
  • Lecture (Conference)
    55. Kraftwerkstechnisches Kolloquium, 10.-11.10.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37658


Ultrafast X-ray tomography and its application to studying particle flows

Hampel, U.; Barthel, F.; Baecke, A. M.; Bieberle, A.; Bieberle, M.; Lecrivain, G.; Papapetrou, T. N.; Windisch, D.

Ultrafast X-ray tomography is a key imaging technique for multiphase flows. In particular, it has been used with great success for studying particle flows. Here, we give an overview of recent developments in the scanner hardware and data processing, and demonstrate the use of this technique to the study of particle segregation in a rotating drum as an exemplary test case for analysing industrial particle mixing systems.

Keywords: Ultrafast X-ray tomography; Particle flow; Mixing and segregation

Involved research facilities

  • TOPFLOW Facility
  • Contribution to proceedings
    11th World Congress on Industrial Process Tomography (WCIPT-11), 06.-08.09.2023, Mexico City, Mexico
  • Lecture (Conference)
    11th World Congress on Industrial Process Tomography (WCIPT-11), 06.-08.09.2023, Mexico City, Mexico

Permalink: https://www.hzdr.de/publications/Publ-37657


Entwicklung von Messtechnik zur Beprobung kontaminierter Betonstrukturen im Sicherheitsbehälter von Druckwasserreaktoren während des Kraftwerksrückbaus (KOBEKA)

Bertram, W.; Hampel, U.; Anthofer, A.; Dirk Döhler, D.; Herrmann, M.; Jansen, S.; Kahle, P.; Kormoll, T.; Kosowski, K.; Lösch, H.; Mechtcherine, V.; Nurjahan, T.; Rauf, A.; Reinecke, A.-M.; Schleicher, E.; Schröfl, C.; Werner, T.

Während der Beprobung der Betonstrukturen des Reaktorgebäudes im Kernkraftwerk Stade wurden tief eingedrungene Kontaminationen im unteren Teil des Reaktorsicherheitsbehälters, der so genannten Betonkalotte, vorgefunden. Diese waren durch Primärkreiswasser aus verschiedenen Systemen während des Anlagenbetriebes eingetragen worden. Das Durchdringen der wasserabweisenden Dekontaminationsbeschichtung und die weitere Ausbreitung entlang von Arbeitsfugen hatten zu großräumiger Kontamination in der Größenordnung des bis zu 100-fachen der Freigabewerte geführt. Durch fehlende Detailkenntnisse zur Kontaminationsverteilung gestaltete sich der Rückbau erheblich zeit- und kostenaufwändiger als ursprünglich veranschlagt. Es ist davon auszugehen, dass dieses Problem andere Kernkraftwerke in Deutschland und weltweit betrifft.
Die Beprobung des Betons mittels Kernbohrungen ist durch erschwerte Zugänglichkeit des Beprobungsortes, baustatische Randbedingungen und Kosten eingeschränkt. Eine Alternative zu Kernbohrungen sind Bohrungen ins Volle. Wegen der schlankeren Bohrlöcher können deutlich mehr Bohrungen gesetzt werden, ohne die strukturelle Integrität des Reaktorgebäudes in unannehmbarem Maße zu schwächen. Allerdings fehlt es dann an Bohrkernen für eine Analytik. Das Vorhaben KOBEKA (gefördert durch das BMBF im Rahmen des Förderkonzeptes „FORKA - Forschung für den Rückbau kerntechnischer Anlagen“) beschäftigt sich daher mit der Entwicklung innovativer Messtechnik zur Beprobung und in-situ Messung in solchen schlanken Bohrlöchern. Entwickelt werden Technologien zur Detektion von Kontaminationen und zur Bestimmung des Nuklidvektors. Weiterhin sollen Feuchte und Porosität der Betonmatrix sowie die Präsenz von Borverbindungen ermittelt werden. Die Kenntnis der Porosität dient der Bestimmung der Lage von Arbeitsfugen, die Kenntnis des Feuchte- und Borgehalts geben Evidenz über eingedrungenes Primärkreiswasser. Zusätzlich ist die hydraulische Permeabilität zwischen verschiedenen Bohrungen von Interesse, um mögliche Transportwege über Arbeitsfugen zu identifizieren und damit die Beprobungsplanung zu unterstützen. Ebenfalls werden Werkzeuge zur Kartierung und elektronischen Dokumentation der Befunde entwickelt.

Keywords: Rückbau von Kernkraftwerken

Involved research facilities

  • TOPFLOW Facility
  • Contribution to proceedings
    KONTEC 2023: Internationales Symposium „Konditionierung radioaktiver Betriebs- und Stilllegungsabfälle“, 30.08.-01.09.2023, Dresden, Deutschland
  • Lecture (Conference)
    KONTEC 2023: Internationales Symposium „Konditionierung radioaktiver Betriebs- und Stilllegungsabfälle“, 30.08.-01.09.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37656


Efficient ultrafast field-driven spin current generation for spintronic terahertz frequency conversion (raw data in Origin project)

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

In this Origin project file (*.opju) we provide an access to the raw data which we obtained and analyzed. The result of our analysis are presented in the publication "Efficient ultrafast field-driven spin current generation for spintronic terahertz frequency conversion".

Keywords: spin current; spintronics; terahertz frequency conversion; high THz field

Involved research facilities

  • T-ELBE

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Permalink: https://www.hzdr.de/publications/Publ-37655


High Field Suppression of Bremsstrahlung Emission in High-Intensity Laser-Plasma Interactions

Habibi, M.; Toncian, T.
Project Leader: Toncian, Toma

This dissertation investigates the effect of macroscopic electric and magnetic fields on bremsstrahlung emission in high-intensity laser-plasma interactions, specifically in the regime of relativistic-induced transparency. The Particle-in-Cell (PIC) EPOCH simulation code has been updated to incorporate a new suppression mechanism influenced by the presence of intense electric and magnetic fields. The study compared the bremsstrahlung emissions generated under relativistic transparency conditions using three distinct models: the original bremsstrahlung model in the EPOCH code, the model modified by the magnetic suppression (MS) effect, and the newly proposed suppression model by the electric and magnetic suppression (EMS) effect.
The results demonstrated that macroscopic electric and magnetic fields have a significant effect on the decrease of bremsstrahlung photons in laser-plasma interactions. In addition, differences in electron dynamics were observed between the EPOCH and EMS models, indicating that the suppression mechanism can influence the dynamics of electron acceleration. The study provides insight into bremsstrahlung emission under extreme conditions, where energetic electrons travel through a relativistically transparent plasma while being deflected by magnetic fields with MT-level strength.
On the basis of the results, it is suggested that the implementation of conventional bremsstrahlung in PIC codes be modified to account for the discussed suppression effect.

Keywords: EPOCH; PIC code; EMS model; Bremsstrahlung Suppression; Relativistic Transparency

Involved research facilities

  • HIBEF

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Permalink: https://www.hzdr.de/publications/Publ-37654


Monitoring Pancreatic α-Amylase of Postoperative Patients with Droplet-Based Microfluidics

Zhao, X.; Kolbinger, F. R.; Distler, M.; Weitz, J.; Makarov, D.; Bachmann, M.; Baraban, L.

This study presents a groundbreaking portable droplet-based microfluidic device capable of real-time detecting α-amylase activity in drainage fluids for postoperative patient monitoring. By implementing this strategy, the determination time for α-amylase levels is significantly reduced from several hours, the current clinical standard, to just three minutes.1 The device demonstrates a remarkable improvement in detection sensitivity, reaching a detection limit of 7 nmol/s·L, an order of magnitude enhancement compared to the recent state of the art.2 Moreover, a mere 10 μL of drain liquid and reagent are necessary for each measurement reducing material requirement and waste.3,4 Crucially, this real-time continuous detection strategy circumvents delays in diagnosis, ensuring prompt treatment of life-threatening complications. Figure 1A illustrates the schematic representation of real-time α-amylase detection in the microfluidic device. A minute volume of patient exudate is continuously gathered and enclosed with a starch reagent within 200 nL droplets. The emitted fluorescence intensity is monitored as a measure of α-amylase activity. Distinct fluorescence intensities were emitted when various concentrations of standard amylase solutions reacted with a fixed quantity of reagent, as shown in Figure 1B, by which the calibration curve is obtained (Figure 1C). A total of 32 patient samples were assessed, and the amylase concentration was determined using the established calibration curve. Evaluation of the results, as depicted in Figure 1D, reveals the dependable detection accuracy of the droplet-based microfluidic device compared to clinical gold-standard methods.

  • Open Access Logo Poster
    The 27th International Conference on Miniaturized Systems for Chemistry and Life Sciences (µTAS 2023), 15-19 October 2023 Katowice, Poland, 15.-19.10.2023, Katowice, Poland

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Permalink: https://www.hzdr.de/publications/Publ-37653


Towards Data-Driven Optimization of Experiments in Photon Science

Kelling, J.; Willmann, A.; Thiessenhusen, E.; Rustamov, J.; Aguilar, R. A.; Hänel, T.; Hoffmann, N.; Debus, A.; Juckeland, G.; Bachmann, M.

High-fidelity (computer-) experiments are very expensive to perform, hence
extracting as much information as possible from the collected data is vital.
We present methods to estimate experiment outcomes based on ingested past data,
to steer further sample acquisition both by suggesting paths for maximized
uncertainty reduction and highlighting sensitivities on inputs, with use-cases
from laser-light propagation and laser-plasma interactions to electron-bunch
kinetics.

Keywords: surrogate models; machine learning; digital twins; laser-plasma accelerators; free-electron laser

Involved research facilities

  • Draco
  • Open Access Logo Invited lecture (Conferences)
    9th Annual MT meeting, 09.-11.10.2023, Karlsruhe, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-37652


Defect Engineering of Ta3N5 Photoanodes: Enhancing Charge Transport and Photoconversion Efficiencies via Ti Doping

Wagner, L. I.; Sirotti, E.; Brune, O.; Grötzner, G.; Eichhorn, J.; Santra, S.; Munnik, F.; Olivi, L.; Pollastri, S.; Streibel, V.; Sharp, I. D.

Ta3N5 shows great potential as a semiconductor photoanode for solar water splitting. However, its performance is hindered by poor charge carrier transport and trapping due to a high density of defects that introduce electronic states deep within its bandgap. Here, we demonstrate that controlled Ti doping of Ta3N5 can dramatically reduce the concentration of deep-level defects and enhance its photoelectrochemical performance, yielding a sevenfold increase in photocurrent density and a 300 mV cathodic shift in photocurrent onset potential compared to undoped material. Comprehensive characterization reveals that Ti+4 ions substitute Ta+5 lattice sites, thereby introducing compensating acceptor states, reducing concentrations of nitrogen vacancies and reduced Ta+3 states, and thereby suppressing trapping and recombination. Importantly, Ti doping offers distinct advantages compared to Zr, an intensively investigated dopant of Ta3N5 in the same group of the periodic table. Specifically, Ti+4 and Ta+5 have more similar atomic radii, allowing for substitution without introducing lattice strain, and Ti exhibits a lower affinity for oxygen than Zr, enabling its incorporation without increasing the oxygen donor content. Consequently, we demonstrate that the electrical conductivity can be tuned by over seven orders of magnitude. Thus, Ti doping in Ta3N5 provides a powerful basis for precisely engineering the optoelectronic characteristics of Ta3N5 and to substantially improve its functional characteristics as an advanced photoelectrode for solar fuels applications.

Keywords: solar water splitting; tantalum nitride (Ta3N5); doping; defect engineering; charge carrier engineer

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Permalink: https://www.hzdr.de/publications/Publ-37651


FVV1455: CFD Simulation of Droplet Separators

Singh, D.; Boden, S.; Schlegel, F.
Producer: Schlottke, Jan; Producer: Weber, Andreas

For industrial applications, the two-fluid model is preferred due to its efficient modelling of small-scale interfaces. Whereas, a thin film model, based on a long wave approximation, is used for the unresolved interfaces to obtain the film features by solving the 2D Navier-Stokes equations for wall films. Within the project, the target is to develop an experimentally validated 3D-CFD model to investigate the separation efficiency of droplet separators for fuel cell systems. A hybrid model is developed, which couples the two-fluid model with a thin film model via mass transfer terms for droplet deposition, droplet entrainment and film separation. A two-way coupling between droplets and the thin film is established using mass and momentum source terms, derived analytical and from available experiments. The droplet separator is an essential component of an automotive fuel cell system that segregates a significant amount of liquid fractions from the air-water mixture. The flow dynamics inside a droplet separator consist of a dispersed gas and liquid with a wall adhered thin liquid film. The modelling is divided into the following stages due to the complex fluidic phenomenon inside a generic droplet separator:

  1. Droplet deposition model,
  2. Film separation model,
  3. Film transition model, and
  4. Population balance model.

The numerical simulations are validated and fine-tuned with experiments carried out at HZDR.

Keywords: Numerical Simulation; Droplets; Film Modeling; Multiphase Flow; Fuel Cell; Separation; Automotive

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Permalink: https://www.hzdr.de/publications/Publ-37650


Interfacial selective separation of fine particles for the recycling of PEM electrolyzer exploiting particle-fluid interactions in multiphase systems

Ahn, S.; Rudolph, M.

For large-scale of green hydrogen production via water electrolysis, catalysts containing critical materials in a submicron down to nanometer scale have advantages as active materials in the application. The circularity of critical raw materials such as PGM after the utilization phase becomes and thus recycling processes for end-of-life water electrolyzers need to be developed.
In the range of ultra-fine particle systems (0.1 to 10 µm), established techniques like flotation have challenges for their efficient separation. Liquid-liquid phase transfer is one possible alternative approach for the selective separation of such fine particles. In this phase transfer process, the interactions between particles and oil droplets are greater than those between particles and air bubbles in classic flotation. Hence, particles can be enriched much more efficiently at the oil-water interfaces.
In this study, titanium oxide TiO2 and carbon black are separated representing anode and cathode material in polymer electrolyte membrane (PEM) water electrolyzer respectively. Wettability characterization studies revealed their significant contrast in hydrophobicity. TiO2 exhibits a rather hydrophilic surface while carbon black shows hydrophobic characteristic, however there are still many unknown properties of the surface characteristics of various carbon black variants.
By using the analytic particle solvent extraction (APSE) method, particle mixtures can be transferred into organic and aqueous phases respectively, and selectively separated with high recovery. This approach provides a contribution to scale-up the recycling processes of PEM water electrolyzers.

Keywords: Fine particles; Recycling; Particle separation; PEM water electrolyzer; Wettability

  • Lecture (Conference)
    Jahrestreffen der DECHEMA-Fachgruppen Kristallisation, Grenzflächenbestimmte Systeme und Prozesse sowie Mechanische Flüssigkeitsabtrennung, 09.-10.03.2023, Frankfurt am Main, Germany

Permalink: https://www.hzdr.de/publications/Publ-37649


Application of particle-fluid interactions for selective separation of fine particles for the recycling of HTEL electrolyzer

Ahn, S.; Rudolph, M.

For efficient renewable energy circulation, hydrogen production via water electrolysis technology has been developed over past decades. Amongst three technologies, high temperature water electrolysis (HTEL) is considered as a promising technology because of its high efficiency. Rare earth elements are the best candidates to make the cell more promising. However, reaching a long-term operation is an unsolved challenge because the durability of used ceramic materials is still an issue. Hence, development of the recycling processes for these critical raw materials is an important topic.
Ceramic materials used in HTEL cell have a similar surface property in terms of wettability. For this reason, fine particles cannot be separated without help from surfactants. In this study, representative materials such as Nickel oxide (NiO), Lanthanum strontium manganite (LSM), Yttria stabilized zirconia (YSZ), and Zirconium (ZrO2) oxide are used and their surface charge are investigated. Depending on the pH value, materials show change of their surface charge. Considering their electric charge, different surfactants applied to drive the particle surface hydrophobic. Since NiO and LSM have positive surface charge in base dispersion, particles may be hydrophobized with anion surfactant. Wettability of the YSZ and ZrO2, materials with opposite surface charge, changed by addition of cation surfactant. Their changed wettability can be described by using particle attachment on single air bubbles. Additional approach by using liquid-liquid phase transfer explain their behavior at the oil-water interfaces. This approach provides a contribution to scale-up the recycling processes of HTEL cells.

Keywords: Fine particles; Recycling; Particle separation; Interfaces; high temperature electrolyzer

  • Lecture (Conference)
    14th European Congress of Chemical Engineering and 7th European Congress of Applied Biotechnology, 17.-21.09.2023, Berlin, Germany

Permalink: https://www.hzdr.de/publications/Publ-37648


Application of novel hydrophobic binders for the selective agglomeration of fine particles for the recycling of PEM water electrolyzers

Ahn, S.; Rudolph, M.

With the tremendous increase of hydrogen production via water electrolysis technology, the development of a recycling process for valuable raw materials is emerging as an important issue for a functional circular economy. Especially, platinum group metals such as Iridium oxide and platinum particles on carbon black are used as active materials in the polymer electrolyte membrane (PEM) water electrolyzer. Since the size range of those particles is well below 100 µm, the development of mechanical separation technologies has not been well established. Conventional mechanical separation processes, such as flotation, are not effective for particles in the submicron scale.
According to previous investigations, each material on both electrodes shows a contrast in surface properties in terms of (de)wett(ing)ability. Cathode materials such as carbon black exhibit a hydrophobic character, while anode materials like Iridium oxide show a rather good affinity for water. For this study, pure particle fractions of carbon black and titanium oxide are used as representative materials.
Oil agglomeration is one of the widespread technologies to recover hydrophobic particles. As reported by Kim Van Netten in 2017, the separation of fine coal particles from a suspension was achieved by using a new type of hydrophobic binder comprising only 5 % of organic liquid. In this study, this novel organic emulsion system is applied to separate ultra-fine carbon black particles selectively and to assess the functionality of the emulsion to develop a process for PEM recycling. Those water-in-oil-in-water emulsion droplets enable to reach the agglomeration of carbon black particles in a few seconds which is a promising pre-treatment result for subsequent enrichment.

Keywords: Fine particles; Wettability; Recycling; PEM water electrolyzer

  • Poster
    PARTEC 2023, International Congress on Particle Technology, 26.-28.09.2023, Nürnberg, Germany

Permalink: https://www.hzdr.de/publications/Publ-37647


Development of Fine Particle Mechanical Separation Processes with Representative Catalyst Materials for Recycling PEM Water Electrolyzers Exploiting their Wetting Characteristics

Ahn, S.; Rudolph, M.

Demand for technologies using water electrolysis to produce green hydrogen is increasing, although recycling research on membrane electrode assemblies, which contain various precious and highly critical metals, is still limited. This study therefore aims at exploiting the feasibility of fine particle separation processes based on the difference in hydrophobicity of the ultrafine materials used as catalysts in polymer electrolyte membrane electrolyzers and at providing a fundamental study with representative materials of carbon black and TiO2. Since the cathode materials including carbon black are hydrophobic and the anode materials as well as TiO2 are hydrophilic, the characterizations of their various surface properties such as zeta potentials, dispersion characteristics, and bubble coverage angle tests have been investigated. In addition, using liquid-liquid particle extraction in a mixture model, 99 % of carbon black is recovered in the organic phase and 97 % of TiO2 is selectively separated in the aqueous phase with the help of the dispersant, sodium hexametaphosphate.

Keywords: Fine particles; Interfaces; PEM water electrolyzer; Surface chemistry; Wettability

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Permalink: https://www.hzdr.de/publications/Publ-37646


Magnetic State Control of Non-van der Waals 2D Materials by Hydrogenation

Barnowsky, T.; Curtarolo, S.; Krasheninnikov, A. V.; Heine, T.; Friedrich, R.

Controlling the magnetic state of two-dimensional (2D) materials is crucial for spintronic applications.
By employing data-mining and autonomous density functional theory calculations, we
demonstrate the switching of magnetic properties of 2D non-van der Waals materials upon hydrogen
passivation. The magnetic configurations are tuned to states with flipped and enhanced moments.
For 2D CdTiO3 - a nonmagnetic compound in the pristine case - we observe an onset of ferromagnetism
upon hydrogenation. Further investigation of the magnetization density of the pristine
and passivated systems provides a detailed analysis of modified local spin symmetries and the emergence
of ferromagnetism. Our results indicate that selective surface passivation is a powerful tool
for tailoring magnetic properties of nanomaterials such as non-vdW 2D compounds.

Keywords: 2D materials; non-van der Waals compounds; passivation; magnetism; data-driven research; computational materials science; high-throughput computing

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Permalink: https://www.hzdr.de/publications/Publ-37645


Preparation of 18F-Labeled Tracers Targeting Fibroblast Activation Protein via Sulfur [18F]Fluoride Exchange Reaction

Craig, A.; Kogler, J.; Laube, M.; Ullrich, M.; Donat, C.; Wodtke, R.; Kopka, K.; Stadlbauer, S.

Early detection and treatment of cancers can significantly increase patient prognosis and enhance the quality of life of affected patients. The emerging significance of the tumor microenvironment (TME) as a new frontier for cancer diagnosis and therapy may be exploited by radiolabeled tracers for diagnostic imaging techniques such as positron emission tomography (PET). Cancer-associated fibroblasts (CAFs) within the TME are identified by biomarkers such as fibroblast activation protein alpha (FAPα), which are expressed on their surfaces. Targeting FAPα using small molecule 18F-labeled inhibitors (FAPIs) have recently garnered significant attention for non-invasive tumor visualization using PET. Currently, the predominant 18F-fluorination method for radiolabeling FAPIs involves chelation-based radiofluorination strategies using aluminum [18F]fluoride ([18F]AlF). Herein, a powerful radiofluorination protocol for the preparation of two 18F-labeled FAPIs via the sulfur [18F]fluoride exchange ([18F]SuFEx) reaction and preliminary biological evaluation is disclosed.

Keywords: Automation; cancer-associated fibroblast; FAPI; 18F-fluorination; positron emission tomography (PET); [18F]SuFEx

Involved research facilities

  • ZRT

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Permalink: https://www.hzdr.de/publications/Publ-37644


Data publication: Influence of oxidic and metallic interfaces on the magnetic damping of Permalloy thin films

Ney, V.; Salikhov, R.; Lenz, K.; Hellwig, O.; Lindner, J.; Ney, A.

FMR Rohdaten und Auswertungen.

Keywords: Thin films; ferromagnetism; ferromagnetic resonance; anisotropy; linewidth

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Permalink: https://www.hzdr.de/publications/Publ-37643


Data publication: Magnetic State Control of Non-van der Waals 2D Materials by Hydrogenation

Barnowsky, T.; Curtarolo, S.; Krasheninnikov, A.; Heine, T.; Friedrich, R.

This dataset includes the primary research data for the publication "Magnetic State Control of Non-van der Waals 2D Materials by Hydrogenation".

Keywords: 2D materials; magnetism; non-van der Waals compounds; passivation; data-driven research; computational materials science; high-throughput computing

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Permalink: https://www.hzdr.de/publications/Publ-37642


A Monte Carlo photonic model to simulate the UV inactivation of airborne microorganisms

Cavagnola, M. A.; Hampel, U.; Lecrivain, G.

A model based on a photonic approach is developed, that allows us to track each of the flowing airborne microorganisms and predict, by using a kinetic Monte Carlo algorithm, whether it is active or not.

  • Poster
    HZDR - PhD seminar, 17.-19.10.2023, Rittergut Schilbach, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37641


Data publication: Control of Four-Magnon Scattering by Pure Spin Current in a Magnonic Waveguide

Hache, T.; Körber, L.; Hula, T.; Lenz, K.; Kakay, A.; Hellwig, O.; Lindner, J.; Faßbender, J.; Schultheiß, H.

This dataset contains the numerical and experimental data (both raw and evaluated), labbooks associated with the measurements for our paper published in Physical Review Applied.

Keywords: spin waves; magnetism; BLS; four-magnon scattering; spin current; spintronics; magnonics

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Permalink: https://www.hzdr.de/publications/Publ-37640


Investigations on the Eu(III) translocation in hydroponically grown plants

Klotzsche, M.; Steudtner, R.; Vogel, M.; Drobot, B.; Schymura, S.; Raff, J.

Lanthanides (Ln) have become indispensable for science, technology and everyday objects. The intense
exploitation of Ln-bearing ores, their further processing as well as the improper disposal of high-tech
products lead to anthropogenic increased levels of these metals in the environment. Knowledge about their
fate in the plant biosphere is crucial to maintain food safety and to develop feasible phytoremediation
strategies.
In our research, we aim to follow Eu(III) on its journey through hydroponically grown sand oat (Avena
strigosa) – a potential candidate for phytoremediation – from initial exposure and cellular uptake over
localization in root tissue followed by translocation via plant sap into aboveground parts and the metal’s
distribution in leaves. Therefore, we apply a set of spectroscopic (TRLFS, ICP-MS), microscopic (chemical
microscopy), chromatographic (HPLC) and photographic (autoradiography) analysis techniques. In short,
following an exposure time of 96 h with 200 μM Eu(III), chemical microscopy reveals roots hairs and root
tips a s well as epidermis cells to be one uptake pathway for the Ln. Quantification of the metal content in
roots and shoots by ashing and subsequent acid digestion unveils that the majority of Eu(III) accumulates
in the roots (≈14242 μg/gdry weight) whereas only 35 μg/gdry weight) is translocated into the green plant parts.
The upwards transport of Eu(III) takes place via the xylem sap, in which organic acids are probably
responsible for Eu(III) translocation in measurable quantity. In order to visualize not solely the microscopic
distribution of Eu(III) in roots, but also account for the shoots, experiments with the radioactive isotope
Eu-152 were conducted and the dried plant was scrutinized by autoradiography (Fig. 1).
These studies contributed to a comprehensive understanding of the fate of Ln(III) in plants. Investigations
regarding the uptake and distribution of Cm(III) are currently under way.

Keywords: bioassociation; europium; lanthanide; plant; chemical microscopy

  • Lecture (Conference)
    21st Jena Remediation Symposium, 05.-06.10.2023, Jena, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37639


Saturation of the anomalous Hall effect at high magnetic fields in altermagnetic RuO2

Tschirner, T.; Keßler, P.; Gonzalez Betancourt, R. D.; Kotte, T.; Kriegner, D.; Büchner, B.; Dufouleur, J.; Kamp, M.; Jovic, V.; Smejkal, L.; Sinova, J.; Claessen, R.; Jungwirth, T.; Moser, S.; Reichlova, H.; Veyrat, L.

Observations of the anomalous Hall effect in RuO2 and MnTe have demonstrated unconventional time-reversal symmetry breaking in the electronic structure of a recently identified new class of compensated collinear magnets, dubbed altermagnets. While in MnTe, the unconventional anomalous Hall signal accompanied by a vanishing magnetization is observable at remanence, the anomalous Hall effect in RuO2 is excluded by symmetry for the Néel vector pointing along the zero-field [001] easy-axis. Guided by a symmetry analysis and ab initio calculations, a field-induced reorientation of the Néel vector from the easy-axis toward the [110] hard-axis was used to demonstrate the anomalous Hall signal in this altermagnet. We confirm the existence of an anomalous Hall effect in our RuO2 thin-film samples, whose set of magnetic and magneto-transport characteristics is consistent with the earlier report. By performing our measurements at extreme magnetic fields up to 68 T, we reach saturation of the anomalous Hall signal at a field Hc ≃ 55 T that was inaccessible in earlier studies but is consistent with the expected Néel-vector reorientation field.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-37638


Composition-dependent absorption of radiation in semiconducting MSi2Z4 Monolayers

Muhammad, S. R.; Tomasz, W.; Kuc, A. B.; Caterina, C.

The recent synthesis of MoSi2N4 material, along with theoretical predictions encompassing the entire family of chemical analogs, has opened up a new array of low-dimensional materials for a diverse range of optoelectronics and photovoltaics applications. In this study, we conducted state-of-the-art many-body first-principles calculations to analyze the quasi-particle electronic structure of the material class MSi2Z4 (where M = Mo, W, and Z = N, P, As, Sb). All monolayers display a direct band gap at the K point, with the exception of MoSi2N4. In tungsten-based compounds, the fundamental-gap can be adjusted over a significantly broader energy range compared to their molybdenum-based counterparts. Additionally, increasing atomic weight of the Z, both the band gap and exciton binding energies decrease. A noteworthy feature is the absence of a lateral valley (Λ or Q) near the conduction band minimum, indicating potential higher photoluminescence efficiencies compared to conventional transition-metal dichalcogenide monolayers. The optical spectra of these materials are predominantly characterized by tightly bound excitons, leading to an absorption onset in the visible range (for N-based) and in the infrared region (for others). This diversity offers promising opportunities to incorporate these materials and their heterostructures into optoelectronic devices, with tandem solar cells being particularly promising.

Permalink: https://www.hzdr.de/publications/Publ-37637


Understanding warm dense matter: from ab initio simulations to experiments

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] to get
new insights into the behavior of WDM. Moreover, I will show how switching to the imaginary-
time representation allows us to significantly improve the interpretation of X-ray Thomson
scattering (XRTS) experiments, which are a key diagnostic for WDM [3]. Specifically, I will
present a model-free temperature diagnostic [4] based on the well-known principle of detailed
balance, but available for all wave numbers, and a new idea to directly extract the electron—
electron static structure factor from an XRTS measurement [5]. As an outlook, I will show how new
PIMC capabilities will allow to give us novel insights into electronic correlations in warm dense
quantum plasmas, leading to unprecedented agreement between experiments [6] and theory.

[1] M. Bonitz et al., Physics of Plasmas 27, 042710 (2020)
[2] M. Böhme et al., Physical Review Letters 129, 066402 (2022)
[3] S. Glenzer and R. Redmer, Reviews of Modern Physics 81, 1625 (2009)
[4] T. Dornheim et al., Nature Communications 13, 7911 (2022)
[5] T. Dornheim et al., arXiv:2305.15305 (submitted)
[6] T. Döppner et al., Nature 618, 270-275 (2023)

  • Lecture (Conference)
    The 9th annual meeting of the programme "Matter and Technologies", 09.-11.10.2023, Karlsruhe, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37636


Implementing code review in the scientific workflow: Insights from ecology and evolutionary biology

Ivimey-Cook, E. R.; Pick, J. L.; Bairos-Novak, K. R.; Culina, A.; Gould, E.; Grainger, M.; Marshall, B. M.; Moreau, D.; Paquet, M.; Royauté, R.; Sánchez-Tójar, A.; Simoes Silva, I. M.; Windecker, S. M.

Code review increases reliability and improves reproducibility of research. As such, code review is an inevitable step in software development and is common in fields such as computer science. However, despite its importance, code review is noticeably lacking in ecology and evolutionary biology. This is problematic as it facilitates the propagation of coding errors and a reduction in reproducibility and reliability of published results. To address this, we provide a detailed commentary on how to effectively review code, how to set up your project to enable this form of review and detail its possible implementation at several stages throughout the research process. This guide serves as a primer for code review, and adoption of the principles and advice here will go a long way in promoting more open, reliable, and transparent ecology and evolutionary biology.

Keywords: ecology; evolutionary biology; open science; reliability; reproducibility; research process; software development; coding errors

Permalink: https://www.hzdr.de/publications/Publ-37635


Numerical modelling and simulation of electric heater for thermal energy storage system

Bouldorie, J.; Bangalore Mohankumar, M.

As a part of my graduation in engineering school in France and master’s degree, I am doing
my 6-month internship/master thesis in the Helmholtz-Zentrum Dresden-Rossendorf in the Institute
of Fluid Dynamics. The team comprised of my supervisor and PhD student, Mrs. Malini Bangalore
Mohankumar, Dr. Sebastian Unger, PhD student Alexandre Guille Bourdas, and I, is working on a
project of Thermal Energy Storage (TES). This system would store the surplus of electricity when
the production is higher than the demand. The electricity is used in order to heat a storage material.
Indeed, an electrical heater heats a CO2 flow, which will through a tank heating the storage material.
The electrical heater is the subject of my work and thesis.
The choice of the fluid was already determined: the CO2 at atmospheric pressure, as it is non
toxic, non inflammable, low corrosive and has advantageous thermodynamic properties.
Nevertheless, other fluids will be studied in the future. Furthermore, the mass flow rate and the
temperatures are fixed by the process of the other systems, such as the thermal storage cycle and the
power cycle. The mass flow rate is 5 kg/s and the inlet/outlet temperatures are 400°C/1000°C. These
are the only constraints for designing the heater. Then different sizes, geometries of the heater will
be studied in order to determine the configuration of the heater.
In this aim, a review of heaters and heat transfer in the shell part of shell-and-tube heat
exchangers is developed. In fact, few articles are available on the operation of electrical heaters at
high temperature. Moreover, shell-and-tube heat exchangers work in the same way as the heater.
However, the range of temperatures differs, so some work has to be done in order to model the heat
transfer in the heater.
With this in mind, an analytical work is developed, in order to have an order of magnitude of
the heat transfer. In this part, different models and correlations are used, to have a first estimation of
the heater length.
Then, a simulation approach applying numerical methods, such as Computational Fluid
Dynamics (CFD) is done. This approach, allows to determine more accurate results, which include
radiation. However, a focus is necessary on the validity of the model of resolution/radiation on the
software.
Finally, to optimize the heat transfer performance in the heater, the results of different designs
are compared,

Keywords: Thermal energy storage; Supercritical CO2; electrical heater

Involved research facilities

  • TOPFLOW Facility
  • Master thesis
    University of Poitiers, France, 2023
    Mentor: Malini Bangalore Mohankumar
    102 Seiten

Permalink: https://www.hzdr.de/publications/Publ-37634


Metal Deportment in Complex Secondary Raw Materials: The Case of Vanadium in Basic Oxygen Furnace Slags

Renno, A.; Möckel, R.; Frenzel, M.; Ebert, D.; Bachmann, K.; Krause, J.; Gutzmer, J.

With the increasing demand for metalliferous and mineral raw materials and the consequent depletion of the global natural resource base, the possible utilization of secondary raw material sources is receiving more and more attention. In the present study, we present results from a detailed vanadium deportment study of three basic oxygen furnace slag (BOS) samples known to containing elevated bulk concentrations of vanadium. Complementary analytical methods that were used to quantify the abundance and composition of V-containing phases include SEM-based automated mineralogy, X-ray fluorescence analysis, and X-ray powder diffraction as well as electron probe microanalysis. The vanadium deportment was quantified using Monte-Carlo simulations of the data obtained from automated mineralogy and electron microprobe analysis. The total V concentrations identified by XRF are between 1.7 and 2.2 wt.% V. The most important hosts of vanadium are larnite-, brownmillerite- and portlandite-solid solutions. In two samples Ca carbonates also significantly contribute to the V deportment, while wuestite, lime, and native iron do not contribute significantly to the vanadium deportment. A thorough consistency
check identifies considerable uncertainties in the density of the V-bearing phases as the most likely reason to explain
remaining discrepancies between measured and calculated V values

Keywords: Steel slag; Basic oxygen furnace slag; Vanadium-bearing slag; Vanadium; Vanadium deportment

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Permalink: https://www.hzdr.de/publications/Publ-37633


Photonic model for airborne microorganisms inactivation by UV radiation

Cavagnola, M. A.; Eßlinger, F.; Hampel, U.; Ebert, G.; Lecrivain, G.

Since the coming of the COVID-19 pandemic in 2019, virus spreading in confined spaces has been in the spotlight. Ultraviolet germicidal irradiation has proven to be an efficient method of rendering airborne microorganisms inactive. In the present study, a novel model for airborne virus/bacteria inactivation using UV-light is presented. A particle-to-particle photonic approach that takes into account each of the interactions between the microorganism particles and UV-light photons is obtained. The main advantage of the presented model is its faithfulness to the physical reality of the inactivation process, i.e. that the ultraviolet inactivation effect is a stochastic process not a deterministic one. This characteristic allows the model to track and calculate the inactivation success for each of the single particles conforming a particle cloud. The model is validated against published data of inactivation of aerolized Escherichia coli bacteria in a UV-reactor and will be validated experimentally using a seasonal coronavirus in a Potential Aerosol Mass Oxidation Flow Reactor at the Helmholtz-Zentrum in Munich.

  • Poster
    European Aerosol Conference, 04.-08.09.2023, Malaga, Spanien

Permalink: https://www.hzdr.de/publications/Publ-37632


PSMA: Aktuelle und zukünftige Entwicklungen

Kiß, O.

PSMA: Aktuelle und zukünftige Entwicklungen

  • Invited lecture (Conferences)
    29. Jahrestagung der Berlin-Brandenburgischen Gesellschaft für Nuklearmedizin, 10.-11.11.2023, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37631


RIVERSAND: A new tool for efficient computation of catchmentwide erosion rates

Stübner, K.; Balco, G.; Schmeißer, N.

In-situ cosmogenic 10Be (and 26Al) concentrations in alluvial sediments provide a spatially averaged signal of the erosion rate of the catchment area. Catchmentwide erosion rates reflect the production rate of the entire basin, and their calculation requires knowledge of the complete production rate model. Available calculators determine production rates on a pixel-based approach and achieve computational efficiency by relying on a scaling method that ignores geomagnetic field strength variations. Here we introduce a new python-based tool that determines erosion rates based on the hypsometry of the catchment. The method relies on the fact that production rates are much more sensitive to changes in elevation than latitude. Our tool has two main advantages: (1) computation time is short (<30 seconds) and independent of the scaling method; there is no need to neglect magnetic field variations, and (2) because production rate scaling is performed by a widely used online calculator, the results are fully comparable to exposure ages or point-based erosion rates determined with the same calculator; future updates to production rate scaling are immediately effective for catchmentwide erosion rate calculation. We demonstrate in two case studies that (1) for similar scaling methods, our calculator reproduces pixel-based results within a few percent, and (2) erosion rates determined with different scaling methods may differ by >20%, differences can vary systematically with erosion rate, and using a time-constant scaling method may result in a bias in the interpretation of catchmentwide erosion rates.

Keywords: AMS; AMS dating; denudation; erosion; landscape evolution

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Permalink: https://www.hzdr.de/publications/Publ-37630


Photonic model for airborne microorganisms inactivation by UV radiation

Cavagnola, M. A.; Eßlinger, F.; Hampel, U.; Ebert, G.; Lecrivain, G.

Since the coming of the COVID-19 pandemic in 2019, virus spreading in confined spaces has been in the spotlight. Ultraviolet germicidal irradiation (UVGI) has proven to be an efficient method of rendering airborne microorganisms inactive. In the present study, a novel model for airborne microorganisms inactivation using UV-light is presented. A particle-to-particle photonic approach that takes into account each of the interactions between microorganisms and UV-light photons is obtained. The main advantage of the presented model is its faithfulness to to the physical reality of the inactivation process, i.e. that ultraviolet inactivation is a stochastic process not a deterministic one. This characteristic allows the model to track and calculate the inactivation success for each of the single particles conforming a particle cloud. The model is validated against experimental data of SARS Corona-virus 2 inactivation in a UV-reactor and against published data of of aerolized Escherichia coli and Pseudomonas aeruginosa bacteria inactivation.

  • Poster
    CORAERO spring PhD School, 09.05.2023, DLR Göttingen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37629


Three Pleistocene glacial advances and a warm episode during MIS-3: Towards a more complete glacial history of the Pamir Mountains

Stübner, K.; Gadoev, M.; Rugel, G.; Lachner, J.; Bookhagen, B.

Understanding the spatial and temporal variations of Pleistocene glaciations is key to understanding present-day climate-driven glacier changes. Glacial chronologies of high-mountain Asia, which are mostly based on cosmogenic 10Be exposure dating of moraine boulders, remain scarce and often inaccurate due to geologically induced age scatter. We present 53 new 10Be exposure ages from rockslides, glacial sediment deposits and glacial erosion surfaces in the southwestern Pamir. In conjunction with previously published 10Be data, we constrain the timing and extent of three major glacial stages in the Pamir. During the Middle Pleistocene, a continuous ice sheet covered most of the Pamir. This stage is older than 200 ka and may have occurred during Marine Isotope Stages (MIS) 8, 10, or 12. The deep valleys of the western Pamir, which constrast with the east Pamir plateau, are partly attributed to Middle Pleistocene glacial erosion. Successively less extensive glacial advances occurred during MIS-4/5 (between 60 and 100 ka ago) and during MIS-2 (at 18-22 ka). The last glacial maximum was synchronous in most of the Pamir, except for prolonged glaciation of the Muztagh Ata ice cap until 14 ka ago. Similar to today, Late Pleistocene glaciers were precipitation-limited with moisture supplied mostly by westerly winds. An episode of increased mass wasting (e.g. Zuvor rockslide: 34 ± 1 ka) and glacier surging correlates with a peak in δ 18 O values in the Guliya ice core and is attributed to a warmer climate.

Keywords: Central Asia; glacial chronology; cosmogenic nuclide; exposure age; moraine; rockslide

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Permalink: https://www.hzdr.de/publications/Publ-37628


Influence of oxidic and metallic interfaces on the magnetic damping of Permalloy thin films

Ney, V.; Salikhov, R.; Lenz, K.; Hellwig, O.; Lindner, J.; Ney, A.

Magnetic damping within Permalloy (Py) thin films is studied via temperature- and frequencydependent ferromagnetic resonance (FMR) experiments. While the Py thickness is kept constant at 20 nm, the environment at the film interfaces was systematically varied by fabricating a set of Py thin films grown on widely used substrates and capped with common layers, which are assumed to be suitable to prevent oxidation. The resulting frequency- and temperature-dependence of the FMR linewidth significantly deviates from the expected Gilbert-like behavior and especially for oxidic interfaces unwanted non-Gilbert-like contributions to the magnetic damping appear, in particular at low temperatures. It turns out that Py sandwiched in-between metallic capping and buffer layers
of Al exhibits the smallest magnetic damping of purely Gilbert-like nature.

Keywords: Thin films; ferromagnetism; ferromagnetic resonance; anisotropy; linewidth

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  • Secondary publication expected from 11.12.2024

Permalink: https://www.hzdr.de/publications/Publ-37626


Terahertz Twistoptics–Engineering Canalized Phonon Polaritons

Obst, M.; Nörenberg, T.; Álvarez-Pérez, G.; de Oliveira, T.; Taboada-Gutiérrez, J.; Feres, F. H.; Kaps, F. G.; Hatem, O.; Luferau, A.; Nikitin, A. Y.; Klopf, J. M.; Alonso-González, P.; Kehr, S. C.; Eng, L. M.

The terahertz (THz) frequency range is key to studying collective excitations in many crystals and organic molecules. However, due to the large wavelength of THz radiation, the local probing of these excitations in smaller crystalline structures or few-molecule arrangements requires sophisticated methods to confine THz light down to the nanometer length scale, as well as to manipulate such a confined radiation. For this purpose, in recent years, taking advantage of hyperbolic phonon polaritons (HPhPs) in highly anisotropic van der Waals (vdW) materials has emerged as a promising approach, offering a multitude of manipulation options, such as control over the wavefront shape and propagation direction. Here, we demonstrate the THz application of twist-angle-induced HPhP manipulation, designing the propagation of confined THz radiation between 8.39 and 8.98 THz in the vdW material α-molybdenum trioxide (α-MoO3), hence extending twistoptics to this intriguing frequency range. Our images, recorded by near-field optical microscopy, show the frequency- and twist-angle-dependent changes between hyperbolic and elliptic polariton propagation, revealing a polaritonic transition at THz frequencies. As a result, we are able to allocate canalization (highly collimated propagation) of confined THz radiation by carefully adjusting these two parameters, i.e. frequency and twist angle. Specifically, we report polariton canalization in α-MoO3 at 8.67 THz for a twist angle of 50°. Our results demonstrate the precise control and manipulation of confined collective excitations at THz frequencies, particularly offering possibilities for nanophotonic applications.

Keywords: s-SNOM; FEL; FELBE; THz; IR; nearfield spectroscopy; phonon polariton; twisted bilayer

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Permalink: https://www.hzdr.de/publications/Publ-37625


Data publication: Estimation of the yield strength from small punch testing

Altstadt, E.

Finite element simulations of the small punch test are performed.Generic elastic-plastic material properties are used. A systematic variation of the yield stress, ultimate tensile stress and uniform elongation is performed to investigate the effects of these parameters of the uniaxial stress-strain curve on the characteristics of small punch force-deflection curves. Moreover, the effect of sample thickness is studied. It is shown that the currently used elastic-plastic transition force – obtained by bi-linear fitting – does not only depend on the yield strength but also on the work hardening behavior of the material. An alternative definition of the elastic-plastic transition force is proposed, which significantly less depends on the work hardening of the material. The approach is based on the deviation of the force-deflection curve from the analytical elastic slope derived by Reissner's plate theory. The new definition of the transition force leads to significantly reduced dependence of the correlation factor on the geometry of the small punch set-up.

Keywords: small punch test; yield strength; empirical correlation; finite element simulation; plate theory

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Permalink: https://www.hzdr.de/publications/Publ-37624


Challenges for the CFD-Modelling in the Multi-Fluid Framework

Lucas, D.

The need to optimise processes, e.g. in terms of energy consumption and product properties, is leading to an increasing demand from industry to be able to reliably predict multiphase flows or even to simulate them as a digital twin in parallel with industrial processes. Because of the large range of scales to be considered, the Euler-Euler approach is often the only feasible framework for medium and large industrial scales. Improving closure models and bringing together different modelling approaches for different scales of phase interfaces are important tasks to achieve a better reliability. For the latter, a flexible hybrid framework for OpenFOAM was developed at the HZDR, which is presented in the talk. Improving closure models requires a better understanding of local phenomena that influence the interactions between phases. Enhanced possibilities for measurements (e.g. with high-speed cameras and ultra-fast X-ray tomography), growing feasibility of DNS for multiphase flows and the use of artificial intelligence open up new possibilities here. Some recent developments and requirements for future activities are discussed.

Keywords: CFD; multiphase; multiscale

  • Invited lecture (Conferences)
    50 years of International Journal of Multiphase Flows, 30.08.-01.09.2023, Wien, Österreich

Permalink: https://www.hzdr.de/publications/Publ-37623


Data publication: Impact of electronic correlations on high-pressure iron: insights from time-dependent density functional theory

Ramakrishna, K.; Lokamani, M.; Baczewski, A.; Vorberger, J.; Cangi, A.

Simulation and literature data on the electrical and thermal conductivity of high-pressure iron. The raw simulation data was generated from time-dependent density functional theory calculations. Post-processing was applied to obtain the transport properties (conductivities) as described in the associated journal publication. The literature data was compiled from available publication data as referenced in the associated journal publication.

Keywords: Time-dpenedent density functional theory; Electronic structure; Electrical conductivity

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Permalink: https://www.hzdr.de/publications/Publ-37622


Impact of electronic correlations on high-pressure iron: insights from time-dependent density functional theory

Ramakrishna, K.; Lokamani, M.; Baczewski, A.; Vorberger, J.; Cangi, A.

We present a comprehensive investigation of the electrical and thermal conductivity of iron under high pressures at ambient temperature, employing the real-time formulation of time-dependent density functional theory (RT-TDDFT). Specifically, we examine the influence of a Hubbard correction (+U) to account for strong electron correlations. Our calculations based on RT-TDDFT demonstrate that the evaluated electrical conductivity for both high-pressure body-centered cubic (BCC) and hexagonal close-packed (HCP) iron phases agrees well with experimental data. Furthermore, we explore the anisotropy in the thermal conductivity of HCP iron under high pressure, and our findings are consistent with experimental observations. Interestingly, we find that the incorporation of the +U correction significantly impacts the ground state and linear response properties of iron at pressures below 50 GPa, with its influence diminishing as pressure increases. This study offers valuable insights into the influence of electronic correlations on the electronic transport properties of iron under extreme conditions.

Keywords: electrical conductivity; time-dependent density functional theory; transition metals

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Permalink: https://www.hzdr.de/publications/Publ-37621


Density driven granular mixing and segregation in a rotating drum

Papapetrou, T. N.; Lecrivain, G.; Bieberle, M.; Hampel, U.

The shearing of a particle bed composed of two or more species results in spontaneous segregation. This poses problems in many industries, where the mixing of granules and powders is a common process and a homogeneous product is desired. In this work, the segregation dynamics occurring in a horizontal rotating drum filled with two granular species that only differ in density is investigated. In this system, radial segregation is relatively fast and occurs over the course of a few drum rotations. State-of-the art techniques allow the study of segregation dynamics at the end walls of a drum, as well as the observation of slow axial dynamics and the steady state of radial mixing inside the drum bulk. They do not allow, however, continuous observation of the transient radial mixing in the bulk. Using the ultrafast X-ray computer tomography it is possible to take cross-sectional images through the opaque granular systems at 1000 frames per second. The high-speed image sequences from intermediate planes of the drum can reveal the segregation dynamics in the bulk. Here we present experimental results from the transient state of radial mixing for a binary granular system with density difference (density ratio 2.8) and equal size (4 mm) spherical beads in a half-filled drum. Using a dimensionless mixing index (M), we compare the dynamics of radial mixing and segregation in transverse planes in the bulk of the drum, captured with UFXCT, with the dynamics from the circular end caps to highlight wall effects. We also compare two dynamic models for radial mixing and consider the effect of flow on mixing dynamics. We find that second-order dynamics fit better the data than the commonly used first-order, since it accounts for the overshooting mixing dynamics occurring at higher drum speeds. We also find that, compared to the end cap, the dense particle segregation core is larger in the bulk plane and the overshooting in the mixing index is smaller, suggesting a correlation between mixing and flow characteristics, such as the dynamic angle of repose. Our results, because of better describing overmixing, are highly relevant to the pharmaceutical, food and cement industries.

Keywords: Ultrafast X-ray computed tomography; Rotating drum; Granular mixing

Involved research facilities

  • ROFEX
  • Lecture (others)
    Presentation in Prof. Stannarius' group, 12.09.2023, Magdeburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37620


Comparison of straight and zig-zag channel designs for a CO2-sCO2 PCHE in a Thermal Energy Storage

Guille-Bourdas, A. F.

Renewable energy sources are the key for long-term decarbonisation of the energy system. However, the intermittent nature of renewables, such as solar energy or wind energy, does not always meet the energy demand in the electrical grid. Considering the fact that both electricity production and consumption vary independently, balancing the grid is a major challenge for the development of an energy system based on renewable energies. Within this framework, Thermal Energy Storage systems (TES) coupled with a power cycle have gained popularity since they can store energy from renewable sources during the periods of high production and release it when necessary.
To convert thermal energy into electricity, a power cycle is required. Given the relative high temperature range (600 - 1000 °C), supercritical CO2 (sCO2) is the most promising material as working fluid for the power cycle, from efficiency and safety considerations. Thus, the Primary Heat Exchanger (PHX) must be carefully designed as the fluid pressures in the TES and the power cycle are namely 1 - 10 bar and 200 - 250 bar.
A Printed Circuit Heat Exchanger (PCHE) with straight or zigzag channels is numerically studied. A 1D model were developped and Computational Fluid Dynamics (CFD) simulations were conducted to design and to optimize the PCHE.

Keywords: Thermal Energy Storage; Primary Heat Exchanger; Printed Circuit Heat Exchanger; Atmospheric pressured gas; Supercritical fluid; Computational Fluid Dynamics; Nodal 1D model; Opitmization

Involved research facilities

  • TOPFLOW Facility
  • Lecture (Conference)
    ESD – MTET PhD Workshop, 26.-27.09.2023, Friendly Cityhotel Oktopus, Siegburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37619


Pd–Si complexes of the type ClPd(μ²-pyO)₄SiR (R = Me, Ph, Bn, Allyl, κO-(pyO)PdCl(η³-allyl); pyO = pyridine-2-olate): The influence of substituent R on the Pd–Si bond

Wagler, J.; Gericke, R.

The reactions of organosiliconpyridine-2-olates (pyridyl-2-oxysilanes) RSi(pyO)₃ (pyO = pyridine-2-olate, R = Me (1a), Ph (1b), Bn (1c) and Allyl (1d)) and [PdCl₂(NCMe)₂] in chloroform afforded the hexacoordinate silicon complexes RSi(μ²-pyO)₄PdCl (R = Me (2a), Ph (2b), Bn (2c) and Allyl (2d), respectively), which feature a Pd–Si bond, in which the Pd atom is the formal lone pair donor toward Si. The new compounds 2b, 2c, 2d were characterized with multi-nuclear NMR spectroscopy and elemental analysis. The effect of the Si-bound substituent R on the trans-disposed Pd–Si bond was studied by single-crystal X-ray diffraction and computational analyses (e.g., Natural Localized Molecular Orbitals, NLMO; topological analyses of the electron density at the bond critical point with Quantum Theory of Atoms-In-Molecules, QTAIM). A structurally related byproduct, (η³-allyl) ClPd(pyO)Si(μ²-pyO)₄PdCl 2d’, which formed along with target product 2d and features an Si–O bond trans to Pd–Si, was included in this systematic study. Another byproduct from the synthesis of 2d, the pentanuclear complex ClPd(μ²-pyO)₂Si(μ²-pyO)₂Pd(μ²-pyO)₂Si(μ²-pyO)₂PdCl (compound 3) was characterized crystallographically. This compound features pentacoordinate Si atoms within trigonal–bipyramidal Si(O₄Pd) coordination spheres with equatorial Pd–Si bonds to the terminal Pd atoms. The Pd–Si bond situation in this compound was elucidated with the aid of computational analyses. QTAIM analyses of 3 in conjunction with a model compound PdSi4, which features two silyl groups and two silylene ligands, indicate topological properties of the electron density at the Pd–Si bond critical point which are similar to Pd–Si bonds of silyl and silylene compounds. The latter exhibit greater similarity, which indicates features of a Pd←Si bond. In contrast, NLMO analyses of 3 identify a polar covalent Pd–Si bond with predominant Pd contribution (formal Pd→Si donation).

Keywords: Ambidentate ligands; Hypercoordination; NMR spectroscopy; Palladium; Silicon; Single-crystal X-ray diffraction; Topological analysis

Permalink: https://www.hzdr.de/publications/Publ-37618


The revision of the pharmaceutical legislation – it is time to act for nuclear medicine in Europe

Patt, M.; Decristoforo, C.; de Martini, A.; Koole, M.; Oyen, W.; Kiß, O.

The revision of the pharmaceutical legislation – it is time to act for nuclear medicine in Europe

Permalink: https://www.hzdr.de/publications/Publ-37617


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.; Berencen, Y.; Helm, M.

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 sili- con 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. Nev- ertheless, 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 telecom- munication O-band has been recently realized in silicon [1-4]. 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 implan- tation protocol compatible with the complementary-metal-oxide-semiconductor (CMOS) technology to fabri- cate telecom SPEs at desired positions on the nanoscale [5].
[1] M. Hollenbach et al., Optics Express 28, 26111 (2020) [2] W. Redjem et al., Nature Electronics 3, 738 (2020)
[3] Y. Baron et al., ACS Photonics 9, 2337 (2022)
[4] D. B. Higginbottom et al., Nature 607, 266 (2022)
[5] M. Hollenbach et al., Nat. Commun. 13, 7683 (2022)

Keywords: Quantum technology; Single photon emitters; Silicon; Implantation

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  • Invited lecture (Conferences)
    4th Science Workshop of the Program MML, 27.-29.09.2023, Jena, Germany

Permalink: https://www.hzdr.de/publications/Publ-37614


Temperature-dependent Generalized Gradient Approximation for Warm Dense Matter

Ramakrishna, K.

Warm dense matter, density functional theory

  • Open Access Logo Invited lecture (Conferences)
    11th Workshop on High Pressure, Planetary and Plasma Physics (HP4), 25.09.2023, Rostock, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-37613


PREFACE Strongly Coupled Coulomb Systems

Cangi, A.; Moldabekov, Z.; Neilson, D.

This special issue compiles papers presented at the International Conference on Strongly Coupled Coulomb Systems (SCCS) held in July 2022. Organized by The Center for Advanced Systems Understanding at the Helmholtz-Zentrum Dresden-Rossendorf, this conference brought together researchers from diverse disciplines to explore plasma-liquid and condensed-matter systems dominated by strong Coulomb interactions. The conference series, initiated in 1977, has evolved to encompass a wide range of topics in theory, simulation, and experiment, including astrophysical plasmas, dense hydrogen, laser-generated plasmas, and more. This fifteenth edition also featured discussions on the intersection of Coulombic systems with machine-learning methods. These proceedings present a comprehensive overview of research in Strongly Coupled Coulomb Systems and offer insights into this dynamic field.

Keywords: Coulomb systems; Astrophysical plasmas; Dusty plasmas; Electron-hole plasmas; Ultra-cold plasmas; Quark-gluon plasmas; Statistical and kinetic theories; Machine learning; Condensed matter

  • Open Access Logo Contribution to proceedings
    Strongly Coupled Coulomb Systems, 24.-29.07.2022, Görlitz, Deutschland
    Strongly Coupled Coulomb Systems (2022): Wiley-VCH GmbH, e202300110
    DOI: 10.1002/ctpp.202300110

Permalink: https://www.hzdr.de/publications/Publ-37612


Wege zum effizienten Rückbau von Reaktorkomponenten und Betonabschirmung: Berechnung des Aktivitätsinventars und deren Validierung an Bohrkernen sowie Mobilitätsuntersuchungen von Radionukliden“ – WERREBA

Konheiser, J.; Barkleit, A.; Pönitz, E.

Das Ziel des Vorhabens war es, genaue Kenntnisse über die entstandenen radioaktiven Nuk-lide während des Leistungsbetriebs eines Kernkraftwerkes, die zeitliche Veränderung der Ak-tivität und die daraus resultierende Verteilung der Aktivität in den einzelnen Phasen des Rück-baus zu erhalten. Die Aktivitätsverteilungen sollten dabei anlagenspezifisch für den Reaktor-druckbehälter (RDB), dessen Einbauten, den Reaktordeckel und die erste Betonabschirmung (biologisches Schild) bestimmt werden. Dabei lag der Schwerpunkt besonders auf der expe-rimentellen Bestimmung der Nuklidzusammensetzung sowie deren Aktivität und chemischen Bindung im Material. Die Untersuchungen wurden an Originalmaterial sowohl aus dem RDB als auch aus dem Beton durchgeführt und dienen der Validierung und Verifizierung der durchgeführten Rechnungen.
Im Fall der stark aktivierten Reaktorkomponenten könnten den Behörden und Betreibern In-formationen bereitgestellt werden, ob neben der direkten Zerlegung die Methode der Abkling-lagerung als eine ökologische und wirtschaftliche Alternative in Betracht kommt. Mit einer möglichen Zwischenlagerung könnten sowohl die endzulagernde aktive Abfallmenge reduziert als auch wertvolle Metalle wieder recycelt werden. Zusätzlich wird die Strahlenbelastung für das Rückbaupersonal verringert.
Im Fall der Betonabschirmung wurden Aussagen zur möglichen chemischen Mobilität der Radionuklide getroffen, welche direkten Einfluss auf die Rückbaustrategie und die Endlage-rung hat. Denn für beides ist nicht nur die absolute Menge, sondern auch die strukturelle Ein-bindung der Radionuklide im Beton wichtig. Diese ist entscheidend für die Stabilität der Bin-dung der Radionuklide im Beton und damit für den Umfang und die Kinetik möglicher Auflö-sungen mit Übergang in die wässrige Phase während des Rückbaus und im Endlager.

Keywords: Rückbau von KKW; Neutronenfluenzrechnungen; Betonaktivierung; Nuklidbestimmung

  • Open Access Logo Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-127 2023
    ISSN: 2191-8708, eISSN: 2191-8716
    ISSN: 2191-8708

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Permalink: https://www.hzdr.de/publications/Publ-37611


Mixing and Agglomeration of Shredder Fines and Flue Dust

Baecke, A. M.; Renno, A.; Hampel, U.; Lecrivain, G.

Industrial processes are inevitably associated with generating fine-grained particulate matter. Such fine-grained residues rarely find re-entry into industrial value chains; typically they are disposed and become an environmental burden. Prominent examples are dusts from mineral processing, degraded end-of-life fibers, or micro plastic entering the natural environment. The project FINEST will process different residues in an optimized manner to generate value and to minimize hazards. FINEST will design high-value products and inert residues. Material assay, beneficial material mixing and logistic concepts will provide ideal opportunities to transform hazardous end of life products to inert residues and to products generating economic value.
Economic and ecological assessment of waste management concepts will provide op-opportunities to create value by decreased disposal costs. The project assembles a well-tailored network of industry associations, industry companies, SMEs, governmental and non-governmental institutions. Associated institutions will provide the capability to transfer FINEST results to the relevant industrial sectors and potential consumers. The appendant Research School will educate a next generation of experts for leadership positions in industry and academia. A transfer design will consider the transfer of knowledge through careers. Young postgraduate colleagues will accordingly receive tailored education in establishing technology transfer concepts and are expected to conduct internships in the course of their doctoral studentship. A central transfer desk will provide organized knowledge transfer to industry clusters and associations in order to promote joint position papers and to suggest market-shaping policies. Individual TTOs have stated their full support for the screening and exploitation of evolving IP within the sub-projects. FINEST represents an ideal combination of scientific excellence and tailored networking with an application-oriented education of the next generation of leadership personnel for the industry and academia. The project offers a well-structured approach to reduce uncertainties for an actual application of developed technologies and is ready to increase the degree of circularity in the economy by transferring its research, and to contribute to more sustainable value chains.
Fine-grained solid particles from various industrial sources, which would otherwise be discarded, should ideally be processed to valuable products or inert residues. Among others, a) shredder fines from electronics and end-of-life vehicles, and b) flue dusts from non-ferrous metallurgical processes are of timely interest. They contain valuable residuals, such as metals, that can be returned to the industrial cycle instead of being landfilled. This is one aim of the Helmholtz project FINEST in which this work is embedded. In this work, mixing and agglomeration of such particles with a size below 1 mm are investigated for further use in the metallurgical industry. Different particle sizes, shapes and densities are considered, as well as varying moisture content. Most relevant product parameters are the mixture’s homogeneity, agglomerate size and porosity. A strong focus is on the rheological behavior of the bulk goods. A continuum model will be used to simulate mixing and prospectively granulation in a cylindrical bladed mixer. The three phases, namely shredder fines, flue dust and interparticle liquid will be modelled using Computational Fluid Dynamics, adding in a Convection-Dispersion-Segregation-Model for microprocesses of mixing. The latter will introduce a Segregation-Term specifically for density differences among component. We present an experimental setup and methods for the aforementioned investigations. The process is observed experimentally using camera imaging technique and µCT. From the µCT images a mixing index is acquired. Using rapid prototyping mixing and agglomeration equipment can be adapted easily and varied for parameter studies. The results will contribute to improved mixing and agglomeration processes for efficient recycling of fine particles as well as improved understanding of mixing in many other fields, such as pharmaceuticals, construction material and food industry.

Keywords: Mixing; Granulation; Bulk Goods; Computed Tomography; Metallurgical Recycling; Bladed Mixer

  • Poster
    PARTEC, 26.-28.09.2023, Nürnberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37609


Potential of the Julia programming language for high energy physics computing

Eschle, J.; Gal, T.; Giordano, M.; Gras, P.; Hegner, B.; Heinrich, L.; Hernandez Acosta, U.; Kluth, S.; Ling, J.; Mato, P.; Mikhasenko, M.; Moreno Briceño, A.; Pivarski, J.; Samaras-Tsakiris, K.; Schulz, O.; Stewart, G. . . A.; Strube, J.; Vassilev, V.

Research in high energy physics (HEP) requires huge amounts of computing and storage, putting strong constraints on the code speed and resource usage. To meet these requirements, a compiled high-performance language is typically used; while for physicists, who focus on the application when developing the code, better research productivity pleads for a high-level programming language. A popular approach consists of combining Python, used for the high-level interface, and C++, used for the computing-intensive part of the code. A more convenient and efficient approach would be to use a language that provides both high-level programming and high performance. The Julia programming language, developed at MIT especially to allow the use of a single language in research activities, has followed this path. In this paper the applicability of using the Julia language for HEP research is explored, covering the different aspects that are important for HEP code development: runtime performance, handling of large projects, interface with legacy code, distributed computing, training, and ease of programming. The study shows that the HEP community would benefit from a large-scale adoption of this programming language. The HEP-specific foundation libraries that would need to be consolidated are identified

Keywords: Julia programming language; High energy physics; phenomenology

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Permalink: https://www.hzdr.de/publications/Publ-37608


Monte-Carlo event generation for the interaction of x-ray laser fields and hot electrons

Hernandez Acosta, U.

We present a novel approach for an event generator inherently using exact QED descriptions to predict the results of high-energy electron-photon scattering experiments that can be performed at modern x-ray laser facilities.
With the advent of advanced laser systems producing high-frequency x-ray beams, e.g. the EuropeanXFEL as a prominent example, a regime of laser-plasma interaction is reached, where all-optical methods are no longer applicable. Instead, the interaction of hot electrons and the x-ray laser pulse needs to be modeled with a QED-driven approach. Future experiments taking place at HED-HIBEF, LCLS, and other facilities targeting this regime, will encounter processes in x-ray scattering from (laser-driven) relativistic electrons, where the effects of the energy spectrum of the laser field as well as multi-photon interactions can not be neglected anymore.
In contrast to the application window of existing QED-PIC codes, our event generator makes use of the fact, that the classical nonlinearity parameter barely approaches unity in high-frequency regimes. Therefore, based on a momentum-space Furry-picture formulation of strong-field QED, this allows taking the finite bandwidth of the x-ray laser into account in the description of the QED-like multi-photon interaction. Consequently, we exploit these effects in Compton scattering, Breit-Wheeler pair production, and trident pair production in x-ray laser fields.

Keywords: Monte-Carlo event generation; Strong-field QED; X-ray interactions

  • Lecture (Conference)
    5th Conference on Extremely High Intensity Laser Physics (ExHILP 2023), 12.09.2023, Gwangju, South Korea

Permalink: https://www.hzdr.de/publications/Publ-37607


Influence of Dielectric Capping on the Optical Properties of Two-Dimensional Transition Metal Dichalcogenides: Implications for nano optoelectronics

Li, Y.; Steuer, O.; Lin, K.; Samad, F.; Sokolova, D.; Erbe, A.; Helm, M.; Zhou, S.; Prucnal, S.

The properties of transition metal dichalcogenides (TMDCs) are highly sensitive to doping and surface-state defects, making it crucial to fabricate high-performance nanoelectronic devices from defect-free materials and gate dielectrics that have a low interface-state density. In this work, the optical and structural properties of mechanically exfoliated mono-, bi- and trilayer thick TMDCs with Al2O3, Si3N4 or SiO2 as a potential gate dielectric layer are investigated. The photoluminescence (PL) and micro-Raman results indicate that all the dielectrics investigated increase the doping of the TMDCs monolayers, quench the emission of neutral excitons and enhance the trion emission. Plasma enhanced chemical vapour deposition was found to generate more defects in the monolayer TMDCs than atomic layer deposition. We establish the relationship between the dielectric deposition process and the optical properties of TMDCs, which could be of interest for future nanoelectronics based on 2D materials.

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Permalink: https://www.hzdr.de/publications/Publ-37605


What governs the atomic structure of the interface between 2D transition metal dichalcogenides in lateral heterostructures?

Davies, F.; Mehlich, K.; Busse, C.; Krasheninnikov, A.

The development of lateral heterostructures (LHs) based on two- dimensional (2D) materials with similar atomic structure but distinct electronic properties, such as transition metal dichalcogenides (TMDCs), opened a new route towards realisation of optoelectronic devices with unique characteristics. In contrast to van der Waals vertical heterostructures, the covalent bonding at the interface between subsystems in LHs is strong, so that the morphology of the interface, which can be coherent or contain dislocations, strongly a↵ects the properties of the LH. We predict the atomic structure of the interface with account for the mismatch between the primitive cell sizes of the components, and more important, the widths of the joined materials using parameters derived from first-principles calculations. We apply this approach to a variety of TMDCs and set a theoretical limit on when the transition of the interface from coherent to dislocation-type should occur. We validate our theoretical results by comparison with the initial stage of two-dimensional heteropitaxial growth of junctions between MoS2 and TaS2 on Au(111).

Keywords: Transition metal dichalcogenides; ab initio calculations; lateral heterostructures; 2D materials

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Permalink: https://www.hzdr.de/publications/Publ-37604


Machine Learning Meets Quantum Mechanics for Materials

Cangi, A.

This talk will present our research on merging machine learning with quantum mechanics. Electron-nuclear interactions determine all materials' properties, and accurate simulations of electronic structure are essential to address critical scientific questions related to renewable energy, sustainable materials, and semiconductor devices. However, electronic structure simulations face an accuracy-size tradeoff.
I will first present our ongoing efforts on developing the Materials Learning Algorithms (MALA) package to solve the electronic structure problem faster. MALA leverages a combination of neural networks, physically constrained optimization algorithms, and efficient post-processing routines. Next, I will present our work on using physics-informed neural networks to solve the time-dependent Kohn-Sham equations, which describe electron dynamics in response to incident electromagnetic waves.

Keywords: Machine learning; Quantum; Materials science; Neural Networks

  • Invited lecture (Conferences)
    Big data analytical methods for complex systems, 19.10.2023, University of Wroclaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-37603


Transferable and scalable electronic structure simulations with the Materials Learning Algorithms package

Cangi, A.

Interactions between electrons and nuclei in matter determine all materials' properties. Understanding and modeling these interactions is of paramount importance, particularly in addressing critical scientific questions related to renewable energy solutions, sustainable materials, and semiconductor device modeling. However, simulations of the electronic structure face a common constraint—an accuracy-size tradeoff. While it is possible to simulate materials at the quantum level of accuracy, this is typically limited to a few thousand atoms, even with advanced tools like density functional theory (DFT). On the other hand, large-scale simulations often sacrifice predictive power due to necessary approximations.
The Materials Learning Algorithms (MALA) [1] package addresses these challenges by leveraging a combination of neural networks, physically constrained optimization algorithms [2], and efficient post-processing routines. Unlike existing approaches, MALA replaces DFT entirely, providing access to both scalar quantities of interest, such as energies, and volumetric information about the electronic structure, such as the electronic density. Our research has demonstrated that MALA can be applied to systems with arbitrary numbers of atoms (successfully testing up to 100,000 atoms) [3], across various temperature and pressure ranges [4]. We anticipate that MALA will have a significant impact, enabling unprecedented modeling capabilities in the fields of materials science and semiconductor device modeling.

[1] L. Fiedler, Z. A. Moldabekov, X. Shao, K. Jiang, T. Dornheim, M. Pavanello, A. Cangi, Phys. Rev. Res. 4, 043033 (2022).
[2] L. Fiedler, N. Hoffmann, P. Mohammed, G. A. Popoola, T. Yovell, V. Oles, J. A. Ellis, S. Rajamanickam, A. Cangi, Mach. Learn.: Sci. Technol. 3, 045008 (2022).
[3] L. Fiedler, N. A. Modine, S. Schmerler, D. J. Vogel, G. A. Popoola, A. P. Thompson, S. Rajamanickam, A. Cangi, Npj Comput. Mater. 9, 115 (2023).
[4] L. Fiedler, N. A. Modine, K. D. Miller, A. Cangi, arXiv:2306.06032 (2023).

Keywords: Machine learning; Electronic structure theory; Materials science; Quantum; Neural networks

  • Lecture (Conference) (Online presentation)
    9th annual meeting of the program "Matter and Technologies", 09.-11.10.2023, Karlsruhe, Germany

Permalink: https://www.hzdr.de/publications/Publ-37602


Machine-Learning for Static and Dynamic Electronic Structure Theory

Fiedler, L.; Shah, K.; Cangi, A.

Machine learning has emerged as a powerful technique for processing large and complex datasets. Recently it has been utilized for both improving the accuracy and accelerating the computational speed of electronic structure theory. In this chapter, we provide the theoretical background of both density functional theory, the most widely used electronic structure method, and machine learning on a generally accessible level. We provide a brief overview of the most impactful results in recent times. We, further, showcase how machine learning is used to advance static and dynamic electronic structure calculations with concrete examples. This chapter highlights that fusing concepts of machine learning and density functional theory holds the promise to greatly advance electronic structure calculations enabling unprecedented applications for in-silico materials discovery and the search for novel chemical reaction pathways.

Keywords: Materials science; Electronic structure; Density functional theory; Machine learning; Neural networks

  • Book chapter
    C. Qu, J. Liu: Machine Learning in Molecular Sciences, Challenges and Advances in Computational Chemistry and Physics, Vol. 36, Cham: Springer, 2023, 978-3-031-37196-7, 113-160
    DOI: 10.1007/978-3-031-37196-7_5

Permalink: https://www.hzdr.de/publications/Publ-37601


Primordial nuclides and low-level counting at Felsenkeller

Turkat, S.

Within cosmology, there are two entirely independent pillars which can jointly drive this field towards precision: Astronomical observations of primordial element abundances and the detailed surveying of the cosmic microwave background. However, the comparatively large uncertainty stemming from the nuclear physics input is currently still hindering this effort, i.e. stemming from the 2H(p,γ)3He reaction. An accurate understanding of this reaction is required for precision data on primordial nucleosynthesis and an independent determination of the cosmological baryon density.
Elsewhere, our Sun is an exceptional object to study stellar physics in general. While we are now able to measure solar neutrinos live on earth, there is a lack of knowledge regarding theoretical predictions of solar neutrino fluxes due to the limited precision (again) stemming from nuclear reactions, i.e. from the 3He(α,γ)7Be reaction. This thesis sheds light on these two nuclear reactions, which both limit our understanding of the universe. While the investigation of the 2H(p,γ)3He reaction will focus on the determination of its cross- section in the vicinity of the Gamow window for the Big Bang nucleosynthesis, the main aim for the 3He(α,γ)7Be reaction will be a measurement of its γ-ray angular distribution at astrophysically relevant energies.
In addition, the installation of an ultra-low background counting setup will be reported which further enables the investigation of the physics of rare events. This is essential for modern nuclear astrophysics, but also relevant for double beta decay physics and the search for dark matter. The presented setup is now the most sensitive in Germany and among the most sensitive ones worldwide.

Keywords: Nuclear astrophysics; Big Bang Nucleosynthesis; Solar neutrinos; Low-level counting; underground physics

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  • Open Access Logo Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-126 2023
    ISSN: 2191-8708, eISSN: 2191-8716

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Permalink: https://www.hzdr.de/publications/Publ-37600


Complex workflows in modern computational science using AiiDA and HELIPORT

Lokamani, M.; Kelling, J.; Pape, D.; Knodel, O.; Juckeland, G.

AiiDA is an open-source Python infrastructure for devising complex workflows associated with modern computational science and streamlining the four core pillars of the ADES model: Automation, Data, Environment, and Sharing. In this contribution, we showcase features of AiiDA like workflow-forging, high-throughput capability and data provenance as implemented in the AiiDA-FLEUR plugin. Finally, we address the possibility of managing AiiDA-projects through HELIPORT.

  • Open Access Logo Lecture (Conference)
    IT4Science-Days 2023, 26.-28.09.2023, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37599


Two-Dimensional Non-van der Waals Materials by Design

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

Two-dimensional (2D) materials are traditionally derived from bulk layered compounds bonded by weak
van der Waals (vdW) forces. In this context, the recent surprising experimental realization of non-vdW
2D compounds obtained from non-layered crystals [1,2] foreshadows a new direction in 2D systems
research. These materials are distinct from traditional 2D sheets as their surface was revealed to be
terminated by cations rather than anions.
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 and also outline
how to tune their properties [3,4]. 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 [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 magnetic properties which can be tuned by proper
chemical functionalization of the 2D sheets making these systems an attractive platform for fundamental
and applied nanoscience.
References
[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. 2201112 (2023).

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  • Lecture (Conference)
    Flatlands beyond graphene 2023, 25.-29.09.2023, Prag, Tschechien

Permalink: https://www.hzdr.de/publications/Publ-37598


Resistance of HNSCC cell models to pan-FGFR inhibition depends on the EMT phenotype associating with clinical outcome

Broghammer, F.; Gouda, M.; Korovina, I.; Brunner, C.; Coppes, R.; Gires, O.; Seifert, M.; Cordes, N.

Background
Focal adhesion signaling networks involving receptor tyrosine kinases (RTK) and integrins control central aspects of cancer cell survival and therapy resistance. However, co-dependencies between these transmembrane receptors and therapeutically exploitable vulnerabilities remain largely elusive in HPV-negative head and neck squamous cell carcinoma (HNSCC).
Methods
The cytotoxic and radiochemosensitizing potential of targeting 10 RTK and β1 integrin were determined in up to 20 different 3D matrix-grown HNSCC cell models. RNA sequencing and protein‑based biochemical assays were performed for molecular and pathway characterization. Bioinformatically identified transcriptomic signatures were applied to patient cohorts to show clinical relevance.
Results
Our findings indicate that fibroblast growth factor receptors (FGFR 1-4) present with the strongest cytotoxic and radiosensitizing potential, both as a monotherapy and when combined with β1 integrin inhibition, surpassing the efficacy of the other assessed RTKs. Pharmacological pan-FGFR inhibition induced a variable response spectrum ranging from cytotoxicity/radiochemosensitization to resistance/radioprotection. The latter prompted us to perform RNA sequencing analysis revealing an association of these contrasting responses to pan-FGFR inhibition with a mesenchymal-to-epithelial (MET) transition for sensitive cell models, whereas resistant cell models exhibited a partial epithelial-to-mesenchymal transition (EMT). In line, inhibition of EMT-associated kinases such as EGFR, PKC and PAK proved effective in reducing the adaptive FGFR-driven resistance. Finally, the translation of the transcriptomic profiles associated with EMT to HNSCC patient cohorts not only demonstrated its prognostic value but also provided conclusive validation of the presence of EMT-related vulnerabilities that can be strategically harnessed for therapeutic intervention.
Conclusions
This study demonstrates that pan-FGFR inhibition elicits both a highly beneficial radiochemosensitizing and a detrimental radioprotective potential in HNSCC cell models. Adaptive EMT-associated resistance appears to be of clinical importance, and we provide effective molecular approaches to exploit this therapeutically.

Keywords: HNSCC; FGFR; Integrin; EMT

Permalink: https://www.hzdr.de/publications/Publ-37597


Targeting colorectal cancer cells using AND-gated Adaptor RevCAR T-cells

González Soto, K. E.; Rodrigues Loureiro, L. R.; Bartsch, T.; Arndt, C.; Kegler, A.; Mitwasi, N.; Drewitz, L.; Hoffmann, L.; Abdelfatah Saleh Hassan, H. A.; Crespo, E.; Mehnert, M.; Daglar, C.; Abken, H.; Momburg, F.; Bachmann, M.; Feldmann, A.

Despite the success of chimeric antigen receptor (CAR) T-cells especially for treating hematological malignancies, critical drawbacks, such as “on-target, off-tumor” toxicities, need to be addressed to improve safety in translating to clinical application. This is especially true, when targeting tumor-associated antigens (TAAs) that are not exclusively expressed by solid tumors but also on healthy tissues. To improve the safety profile, we developed switchable adaptor CAR systems including the RevCAR system. RevCAR T-cells are activated by cross-linking of bifunctional adaptor molecules termed target modules (RevTM). In a further development, we established a Dual-RevCAR system for an AND-gated combinatorial targeting by splitting the stimulatory and co-stimulatory signals of the RevCAR T-cells on two individual CARs. Examples of common markers for colorectal cancer (CRC) are the carcinoembryonic antigen (CEA) and the epithelial cell adhesion molecule (EpCAM), while these antigens are also expressed by healthy cells. Here we describe four novel structurally different RevTMs for targeting of CEA and EpCAM. All anti-CEA and anti-EpCAM RevTMs were validated and the simultaneous targeting of CEA+ and EpCAM+ cancer cells redirected specific in vitro and in vivo killing by Dual-RevCAR T-cells. In summary, we describe the development of CEA and EpCAM specific adaptor RevTMs for monospecific and AND-gated targeting of CRC cells via the RevCAR platform as an improved approach to increase tumor specificity and safety of CAR T-cell therapies.

Keywords: colorectal cancer; CAR T-cells; AND-gate targeting; CEA; EpCAM

Permalink: https://www.hzdr.de/publications/Publ-37596


Chelator Impact: Investigating the Pharmacokinetic Behavior of Copper-64 Labeled PD-L1 Radioligands

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

Background: Programmed cell death ligand 1 (PD-L1) plays a critical role in the tumor microenvironment and overexpression in several solid cancers has been reported. This was associated with a downregulation of the local immune response, specifically of T-cells. Immune checkpoint inhibitors have the potential to reactivate the immune system, but only 30% of patients are considered responders. New diagnostic approaches re therefore needed to determine patient eligibility. Small molecule radiotracers targeting PD-L1 may serve as such diagnostic tools, addressing the heterogeneous PD-L1 expression between and within tumor lesions, thus aiding in therapy decisions. Results: Four small-molecule biphenyl-based PD-L1 ligands were synthesized using a convergent synthetic route with a linear sequence of up to eleven steps. Three different chelators (NODA-GA, CB-TE2A, DiAmSar) were employed to efficiently radiolabel these compounds with copper-64, and a dimeric structure was also synthesized. All radioligands exhibited high proteolytic stability (>95%) for 48 hours post-radiolabeling. Saturation binding yielded moderate affinities ranging from 100 to 265 nM. Conversely, real-time radioligand binding revealed more promising KD values of about 20 nM for [64Cu]Cu-14 and [64Cu]Cu-15. In vivo PET imaging in mice bearing PC3 PD-L1 overexpressing and PD-L1-negative tumors was performed at 0–2, 4–5 and 24–25 h post injection (p.i.). This revealed considerably different pharmacokinetic profiles, depending on the substituted chelator. [64Cu]Cu-14, substituted with NODA-GA, showed renal clearance with low liver uptake, whereas substitution with the cross-bridged cyclam chelator CB-TE2A resulted in a primarily hepatobiliary clearance. Notably, the monomeric DiAmSar radioligand [64Cu]Cu-16 demonstrated a higher liver uptake than [64Cu]Cu-15, but was still renally cleared as evidenced by the lack uptake in gall bladder and intestines. The dimeric structure [64Cu]Cu-17 showed extensive accumulation and trapping in the liver but was also cleared via the renal pathway. After 24 h post-injection, [64Cu]Cu-17 showed the highest accumulation in the PD-L1-overexpressing tumor of all timepoints and all radiotracers, indicating drastically increased circulation time upon dimerization of two PD-L1 binding motifs. Conclusions: This study with biphenyl-based small molecule PD-L1 radioligands clearly shows that the chelator choice significantly influences the pharmacokinetic profile. The NODA-GA-conjugated radioligand [64Cu]Cu-14 exhibited favorable renal clearance; however, the limited uptake in tumors suggests the need for structural modifications to the binding motif for future PD-L1 radiotracers.

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  • PET-Center

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Permalink: https://www.hzdr.de/publications/Publ-37594


Ni-doping assisted modification of the non-collinear antiferromagnetic ordering in Mn5Si3 alloy

Adhikari, S. K.; Roy, R.; Das, S. C.; Sannigrahi, J.; Pramanick, S.; Chattopadhyay, S.; Ritter, C.; Adroja, D. T.; Chatterjee, S.

Ni-doped Mn5Si3 alloys of nominal compositions Mn5-xNixSi3 (for x = 0.05, 0.1, and 0.2) have been investigated through detailed neutron powder diffraction (NPD) studies in zero magnetic field and ambient pressure. At room temperature, all three Ni-doped alloys crystallize with D88 type hexagonal structure having P63∕mcm space group. These alloys undergo paramagnetic → collinear antiferromagnetic → non-collinear antiferromagnetic transitions on cooling from room temperature. A significant decrease in collinear to non-collinear antiferromagnetic transition temperature has been observed with increasing Ni concentration. The magnetic structure of both antiferromagnetic phases can be described by the magnetic propagation vector k = (0,1,0). However, the moment size and the orientation in the non-collinear antiferromagnetic phase are found to be notably affected by the Ni-doping. Approaching near-parallel arrangement of Mn-moments with increasing Ni-doping is found to be responsible for the gradual disappearance of unusual magnetic properties (inverted hysteresis loop, thermomagnetic irreversibility, etc.) observed in Mn5Si3 alloy.

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  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-37591


Robust intralayer antiferromagnetism and tricriticality in the van der Waals compound VBr3

Hovancik, D.; Kratochvilova, M.; Haidamak, T.; Dolezal, P.; Carva, K.; Bendova, A.; Prokleska, J.; Proschek, P.; Misek, M.; Gorbunov, D.; Kotek, J.; Sechovsky, V.; Pospisil, J.

We studied magnetic states and phase transitions in the van der Waals antiferromagnet VBr3 experimentally by specific heat and magnetization measurements of single crystals in high magnetic fields and theoretically by the density functional theory calculations focused on exchange interactions. The magnetization behavior mimics Ising antiferromagnets with magnetic moments pointing out-of-plane due to strong uniaxial magnetocrystalline anisotropy. The out-of-plane magnetic field induces a spin-flip metamagnetic transition of first-order type at low temperatures, while at higher temperatures, the transition becomes continuous. The first-order and continuous transition segments in the field-temperature phase diagram meet at a tricritical point. The magnetization response to the in-plane field manifests a continuous spin canting which is completed at the anisotropy field μ0HMA ≈ 27 T. At higher fields, the two magnetization curves above saturate at the same value of magnetic moment μsat ≈ 1.2 μB/f.u., which is much smaller than the spin-only (S = 1) moment of the V3+ ion. The reduced moment can be explained by the existence of an unquenched orbital magnetic moment antiparallel to the spin. The orbital moment is a key ingredient of a mechanism responsible for the observed large anisotropy. The exact energy evaluation of possible magnetic structures shows that the intralayer zigzag antiferromagnetic (AFM) order is preferred, which renders the AFM ground state significantly more stable against the spin-flip transition than the other options. The calculations also predict that a minimal distortion of the Br ion sublattice causes a radical change of the orbital occupation in the ground state, connected with the formation of the orbital moment and the stability of magnetic order.

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  • High Magnetic Field Laboratory (HLD)

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Permalink: https://www.hzdr.de/publications/Publ-37590


Electronic ground-state hysteresis under magnetic field in GdMn2O5

Balédent, V.; Vaunat, A.; Petit, S.; Nataf, L.; Chattopadhyay, S.; Raymond, S.; Foury-Leylekian, P.

In this paper, we investigate the physical properties of the type-II multiferroic GdMn2O5 material by means of neutron scattering, electric polarization, and magnetization measurements. A complex (T,H) phase diagram shows up, with especially a field-induced magnetic transition around 11 T at low temperature. The high-field phase is accompanied by an additional electric polarization along both the a and b directions, as authorized by symmetry, but never observed experimentally up to now. While the magnetic properties recover their initial states after driving the field back to zero, the polarization along a shows a significant increase. This behavior is observed for all directions of the magnetic field. It constitutes a novel and striking manifestation of the magnetoelectric coupling, resulting in the establishment of a new ground state at zero magnetic field.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

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Data publication: Bispidine Chelators for Radiopharmaceutical Applications with Lanthanide, Actinide and Main Group Metal Ions

Kopp, I.; Cieslik, P.; Anger, K.; Josephy, T.; Neupert, L.; Velmurugan, G.; Gast, M.; Wadepohl, H.; Brühlmann, S. A.; Walther, M.; Kopka, K.; Bachmann, M.; Stephan, H.; Kubeil, M.; Comba, P.

UV/Vis of natural Bi(III)- and Pb(II)-L2 and Bi(III)- and Pb(II)-L3; radio-SEC of 133La-L2; radiolabeling kinetics

Keywords: bispidine; bismuth; lead; chelator; kinetics

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Magnetic particle tracking enabled by planar Hall effect sensors

Schmidtpeter, J.; Zabila, Y.; Sieger, M.; Gundrum, T.; Schubert, C.; Wondrak, T.; Makarov, D.; Eckert, S.

Foam processes are essential in many industrial applications e.g., in froth flotation for material
separation. A detailed understanding of foam flows is vital for improvements in process efficiency. X-
Ray and Neutron imaging can measure flow fields in foam, but require a complex setup and cannot be
performed in-situ. Magnetic particle tracking (MPT) is an alternative approach, that measures the
trajectory of a small magnetic tracer particle inside the foam as a representation of its movement.
Different magnetic field sensors can be applied to detect the magnetic tracer particle. We chose thin film
sensors based on the planar Hall effect (PHE) due to their small size, high sensitivity, high signal-to-
noise ratio and low cost. Our sensors have a size of only 2 mm x 2 mm and are capable of measuring
magnetic fields as low as 10 nT at a sampling frequency of 1 Hz. A sensitivity of 20 V/T at a driving
current of 1 mA was achieved by means of sensor bridging. Our PHE-sensors are almost as precise as
currently used Fluxgate probes, but offer several advantages due to their reduced size. This includes
being installed closer to the area to be measured, enabling finer grids of sensors and decreasing the
detection volume, which increases the precision of the MPT as well as other tomographic methods.

Keywords: planar Hall effect; magnetic field sensors; magnetic particle tracking

  • Lecture (Conference)
    11th World Congress on INDUSTRIAL PROCESS TOMOGRAPHY, 06.-08.09.2023, Ciudad de México, México

Permalink: https://www.hzdr.de/publications/Publ-37586


Pages: [1.] [2.] [3.] [4.] [5.] [6.] [7.] [8.] [9.] [10.] [11.] [12.] [13.] [14.] [15.] [16.] [17.] [18.] [19.] [20.] [21.] [22.] [23.] [24.] [25.] [26.] [27.] [28.] [29.] [30.] [31.] [32.] [33.] [34.] [35.] [36.] [37.] [38.] [39.] [40.] [41.] [42.] [43.] [44.] [45.] [46.] [47.] [48.] [49.] [50.] [51.] [52.] [53.] [54.] [55.] [56.] [57.] [58.] [59.] [60.] [61.] [62.] [63.] [64.] [65.] [66.] [67.] [68.] [69.] [70.] [71.] [72.] [73.] [74.] [75.] [76.] [77.] [78.] [79.] [80.] [81.] [82.] [83.] [84.] [85.] [86.] [87.] [88.] [89.] [90.] [91.] [92.] [93.] [94.] [95.] [96.] [97.] [98.] [99.] [100.] [101.] [102.] [103.] [104.] [105.] [106.] [107.] [108.] [109.] [110.] [111.] [112.] [113.] [114.] [115.] [116.] [117.] [118.] [119.] [120.] [121.] [122.] [123.] [124.] [125.] [126.] [127.] [128.] [129.] [130.] [131.] [132.] [133.] [134.] [135.] [136.] [137.] [138.] [139.] [140.] [141.] [142.] [143.] [144.] [145.] [146.] [147.] [148.] [149.] [150.] [151.] [152.] [153.] [154.] [155.] [156.] [157.] [158.] [159.] [160.] [161.] [162.] [163.] [164.] [165.] [166.] [167.] [168.] [169.] [170.] [171.] [172.] [173.] [174.] [175.] [176.] [177.] [178.] [179.] [180.] [181.] [182.] [183.] [184.] [185.] [186.] [187.] [188.] [189.] [190.] [191.] [192.] [193.] [194.] [195.] [196.] [197.] [198.] [199.] [200.] [201.] [202.] [203.] [204.] [205.] [206.] [207.] [208.] [209.] [210.] [211.] [212.] [213.] [214.] [215.] [216.] [217.] [218.] [219.] [220.] [221.] [222.] [223.] [224.] [225.] [226.] [227.] [228.] [229.] [230.] [231.] [232.] [233.] [234.] [235.] [236.] [237.] [238.] [239.] [240.] [241.] [242.] [243.] [244.] [245.] [246.] [247.] [248.] [249.] [250.] [251.] [252.] [253.] [254.] [255.] [256.] [257.] [258.] [259.] [260.] [261.] [262.] [263.] [264.] [265.] [266.] [267.] [268.] [269.] [270.] [271.] [272.] [273.] [274.] [275.] [276.] [277.] [278.] [279.] [280.] [281.] [282.] [283.] [284.] [285.] [286.] [287.] [288.] [289.] [290.] [291.] [292.] [293.] [294.] [295.] [296.] [297.] [298.] [299.] [300.] [301.] [302.] [303.] [304.] [305.] [306.] [307.] [308.] [309.] [310.] [311.] [312.] [313.] [314.] [315.] [316.] [317.] [318.] [319.] [320.] [321.] [322.] [323.] [324.] [325.] [326.] [327.] [328.] [329.] [330.] [331.] [332.] [333.] [334.] [335.] [336.] [337.] [338.] [339.] [340.] [341.] [342.] [343.] [344.] [345.] [346.] [347.] [348.] [349.]