Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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42291 Publications

Data for bubble column reactor at offshore floating conditions

Heydari, N.; Kipping, R.

Abstract

This set contains experimental data obtained for the investigation of hydrodynamics of a bubble column under offshore floating conditions. The motions roll, pitch, roll and pitch as well as the static bubble column have been investigated. The frequency of the motion has been varried while the flow rate of the gas was set constant to 3 l/min. Experiments were performed in a bubble column with 100 mm inner diameter and hydrodynamics were investigated by meas of wire-mesh sensor measurements. Experiments were perfomed at ambient temperature and pressure conditions.

Keywords: bubble column; offshore conditions; moving column

Involved research facilities

  • TOPFLOW Facility

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Permalink: https://www.hzdr.de/publications/Publ-39860


Formation of multinucleated osteoclasts depends on an oxidized species of cell surface-associated La protein

Leikina, E.; Whitlock, J. M.; Melikov, K.; Zang, W.; Bachmann, M.; Chernomordik, L.

Abstract

The bone-resorbing activity of osteoclasts plays a critical role in the life-long remodeling of our bones that is perturbed in many bone loss diseases. Multinucleated osteoclasts are
formed by the fusion of precursor cells, and larger cells – generated by an increased number of cell fusion events – have higher resorptive activity. We find that osteoclast fusion and bone resorption are promoted by reactive oxygen species (ROS) signaling and by an unconventional low molecular weight species of La protein, located at the osteoclast surface. Here, we develop the hypothesis that La’s unique regulatory role in osteoclast multinucleation and function is controlled by an ROS switch in La trafficking. Using antibodies that recognize reduced or oxidized species of La, we find that differentiating osteoclasts enrich an oxidized species of La at the cell surface, which is distinct from the reduced La species conventionally localized within cell nuclei. ROS signaling triggers the shift from reduced to oxidized La species, its dephosphorylation and delivery to the surface of osteoclasts, where La promotes multinucleation and resorptive activity. Moreover, intracellular ROS signaling in differentiating osteoclasts oxidizes critical cysteine residues in the C-terminal half of La,
producing this unconventional La species that promotes osteoclast fusion. Our findings suggest that
redox signaling induces changes in the location and function of La and may represent a promising
target for novel skeletal therapies.

Permalink: https://www.hzdr.de/publications/Publ-39849


Data publication: Magnetic imaging of thermally switchable antiferromagnetic/ferromagnetic modulated thin films

Griggs, W.; Peasey, A.; Schedin, F.; Anwar, M. S.; Eggert, B.; Mawass, M.-A.; Kronast, F.; Wende, H.; Bali, R.; Thomson, T.

Abstract

Compiled raw data for the following measurements: MFM, VSM, XPEEM, XRD & XRR as well as simulation data.

Keywords: Magnetic thin films; Magnetic patterning; Implantation/irradiation; Magnetic domains; Magnetic phase

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Permalink: https://www.hzdr.de/publications/Publ-39847


Photocathode study in SRF Gun-II at HZDR

Xiang, R.; Arnold, A.; Gatzmaga, S.; Hallilingaiah, G.; Hoffmann, A.; Murcek, P.; Niemczyk, R.; Ryzhov, A.; Teichert, J.

Abstract

HZDR’s SRF Gun-II is an excellent demonstration of SRF technology application in the field of electron sources operating in continuous wave mode. As well known, quality of the photocathode is crucial for operational stability and reliability of an SRF gun. In this contribution, various studies on Cs2Te cathodes, including cleaning, preparation, transport/insertion, RF and beam operation will be summarised. We will look back at the achievements and open issues, and discuss possible improvements and further development.

Keywords: SRF gun; Photocathode; continuous wave mode

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-39842


Prototypical Unknown-Aware Multiview Consistency Learning for Open-Set Cross-Domain Remote Sensing Image Classification

Zhang, X.; Wu, W.; Zhang, M.; Yu, W.; Ghamisi, P.

Abstract

Abstract—Developing a cross-domain classification model for
remote sensing images has drawn significant attention in the
literature. By leveraging the open-set Unsupervised Domain
Adaptation (UDA) technique, the generalization performance of
deep learning models has been improved with the capability to
recognize unknown categories. However, it remains challenging
to explore distribution patterns in the target domain using
uncertain category-wise supervision from unlabeled datasets
while reducing negative transfer caused by unknown samples. To
develop a robust open-set UDA framework, this paper presents
Prototypical Unknown-aware Multiview Consistency Learning
(PUMCL) designed for remote sensing scene classification across
heterogeneous domains. Specifically, it employs a consistency
learning scheme with multiview and multilevel perturbations
to improve feature learning from unlabeled target samples. An
entropy separation strategy is utilized to facilitate open-set detection
and recognition during adaptation, enabling unknown-aware
feature alignment. Furthermore, the introduction of prototypical
constraints optimizes pseudo-label generation through online
denoising and promotes a compact category-wise feature subspace
for improved class separation across domains. Experiments
conducted on six cross-domain scenarios using AID, NWPU, and
UCMD datasets demonstrate the method’s superior performance
compared to nine state-of-the-art approaches, achieving a gain
of 4.5% to 21.2% in mIoU. More importantly, it shows promising
class separability with clear boundaries between different classes
and compact clustering of unknown samples in the feature space.
The source code will be available at https://github.com/zxk688.

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  • Secondary publication expected from 18.10.2025

Permalink: https://www.hzdr.de/publications/Publ-39840


RADEKOR: Speciation and Transfer of Radionuclides (RN) in the Human Organism Especially Taking into Account Decorporation Agents (DA) – a Joint Project, Part II

Heller, A.; Senwitz, C.; Acker, M.; Taut, S.; Stumpf, T.; Barkleit, A.

Abstract

When radionuclides (RN) enter the food chain and are ingested by humans, they pose a potential health risk due to their radio- and chemotoxicity. To minimize the health risk, decorporation agents (DA), which are usually strong complexants, are used after the accidental incorporation of RN to increase their excretion. In order to accurately assess the health risk after oral ingestion and to apply effective decontamination methods, it is essential to understand the processes of (bio)chemistry and speciation of RN at the molecular and cellular level. Within the joint research project RADEKOR: “Speciation and transfer of radionuclides in the human organism especially taking into account decorporation agents”, molecular speciation studies of RN in artificial biofluids of the digestive system of humans and cytotoxicity studies with respective human and rat renal cell lines in vitro both in the absence and presence of DA were performed.

As DA we investigated i) aminopolycarboxylate diethylenetriaminepentaacetic acid DTPA as the only approved and commercially used DA and ii) some promising new chelators like the hydroxypyridinone 3,4,3-(LI-1,2-HOPO) (HOPO) and 1-hydroxy-ethylidene-1,1-diphosphonic acid (HEDP), which was formerly used as a pharmaceutical. First, the complex formation of the non-radioactive An(III) analogue Eu(III) with HEDP in aqueous solution and cell culture medium was studied. Second, Eu(III) and Am(III) cytotoxicity onto kidney cells was investigated in absence and presence of DTPA and HOPO. Finally, the molecular speciation of Eu(III) and Am/Cm(III) with and w/o DTPA and HOPO was studied in both cell culture medium and exposed renal cells. The results of this work contribute to a better understanding of the effect of DA after RN incorporation at the molecular level and support making them more effective in the future.

  • Poster
    Jahrestagung der Fachgruppe Nuklearchemie 2024, 05.-07.11.2024, Karlsruhe, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-39835


RADEKOR: Speciation and Transfer of Radionuclides (RN) in the Human Organism Especially Taking into Account Decorporation Agents (DA) – a Joint Project, Part I

Barkleit, A.; Friedrich, S.; Butscher, D.; Kretzschmar, J.; Stumpf, T.; Heller, A.

Abstract

When radionuclides (RN) enter the food chain and are ingested by humans, they can present significant health risks due to their radiotoxic and chemotoxic properties. To mitigate these risks, decorporation agents (DA), which are typically strong chelators, are employed after accidental RN exposure to facilitate their removal from the body. A thorough understanding of the (bio)chemical behavior and speciation of RN at both the molecular and cellular levels is essential for assessing health impacts and applying effective decontamination techniques. In the joint BMBF project RADEKOR, studies were conducted to investigate the molecular speciation of RN in artificial digestive biofluids, alongside with in vitro cytotoxicity assessments using human and rat kidney cell lines, with and without DA.

As DA we investigated i) aminopolycarboxylate diethylenetriaminepentaacetic acid (DTPA) as the only approved and commercially used DA, ii) alternative aminocarboxylates like ethylenediaminetetraacetic acid (EDTA) or ethyleneglycoltetraacetic acid (EGTA), and iii) some promising new chelators like the hydroxypyridinone 3,4,3-(LI-1,2-HOPO) (HOPO) and 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), which was formerly used as a pharmaceutical. The complex formation of Eu(III) as a non-radioactive analogue for An(III) with EGTA was studied along with its molecular speciation in simulated body fluids in presence and absence of DTPA, EGTA, and HOPO. Furthermore, the molecular speciation of U(VI) in simulated body fluids and cell culture medium as well as its cytotoxicity onto kidney cells was investigated in absence and presence of DTPA, HEDP, and HOPO. The results of this work contribute to a better understanding of the effect of DA after RN incorporation at the molecular level and support making them more effective in the future.

  • Poster
    Jahrestagung der Fachgruppe Nuklearchemie 2024, 05.-07.11.2024, Karlsruhe, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-39834


Unidirectional ray polaritons in twisted asymmetric stacks

Álvarez-Cuervo, J.; Obst, M.; Dixit, S.; Carini, G.; Tresguerres-Mata, A. I. F.; Lanza, C.; Terán-García, E.; Álvarez-Pérez, G.; Álvarez-Tomillo, L. F.; Diaz-Granados, K.; Kowalski, R.; Senerath, A. S.; Mueller, N. S.; Herrer, L.; de Teresa, J. M.; Wasserroth, S.; Klopf, J. M.; Beechem, T.; Wolf, M.; Eng, L. M.; Folland, T. G.; Tarazaga Martín-Luengo, A.; Martín-Sánchez, J.; Kehr, S. C.; Nikitin, A. Y.; Caldwell, J. D.; Alonso-González, P.; Paarmann, A.

Abstract

The vast repository of van der Waals (vdW) materials supporting polaritons offers numerous possibilities to tailor electromagnetic waves at the nanoscale. The development of twistoptics—the modulation of the optical properties by twisting stacks of vdW materials—enables directional propagation of phonon polaritons (PhPs) along a single spatial direction, known as canalization. Here we demonstrate a complementary type of directional propagation of polaritons by reporting the visualization of unidirectional ray polaritons (URPs). They arise naturally in twisted hyperbolic stacks with very different thicknesses of their constituents, demonstrated for homostructures of -MoO3 and heterostructures of -MoO3 and -Ga2O3. Importantly, their ray-like propagation, characterized by large momenta and constant phase, is tunable by both the twist angle and the illumination frequency. Apart from their fundamental importance, our findings introduce twisted asymmetric stacks as efficient platforms for nanoscale directional polariton propagation, opening the door for applications in nanoimaging, (bio)-sensing, or polaritonic thermal management.

Keywords: s-SNOM; FEL; THz; MIR; nanoscopy; phonon polaritons; 2D materials; van der Waals (vdW) materials

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Permalink: https://www.hzdr.de/publications/Publ-39833


Data publication: Boosting electrode performance and bubble management via Direct Laser Interference Patterning

Rox, H.; Ränke, F.; Mädler, J.; Marzec, M. M.; Sokolowski, K.; Baumann, R.; Hamedimastanabad, H.; Yang, X.; Mutschke, G.; Urbas, L.; Lasagni, A. F.; Eckert, K.

Abstract

Direct Laser Intereference Patterning is a promising approach to structure electrodes for alkaline water electrolysis to improve the electrode performance. By increasing the electrochemical active surface area and apply a superhydrophilic surface structure, the overpotential could be decreased significantly. The present data set compares three different spatial period and aspect ratios, defined as the ratio between structure depth and period, at applied current densities of j = 10, 31.62 and 100 mA/cm² in terms of electrode potential, detached bubble size and number of nucleation sites. As electrolyte 1 M KOH was used. All experiments were carried out under ambient conditions (T = 293 K,p = 1 bar).

A.) Description of Data.zip:

An overview of all performed experiments is given in the file Summary.csv. The data is analyzed as described in the corresponding journal publication Boosting electrode performance and bubble management via Direct Laser Interference Patterning. Each data set is stored in a .hdf5-file, with the relevant metadata incorporated into the attributes assigned to the groups/datasets within the .hdf5-file. The data files are structured in groups as follows:

  • Electrochemical Measurement Data
    • Galvanostatic Measurement Data
    • CV double-layer capacitance
    • LSV onset potential
  • Results
    • Detected Bubbles Sideview
    • Detected Bubbles Topview
  • Sideview Raw Images (only for SH2_LS_DoE_01.hdf5)
  • Topview Raw Images (only for SH2_LS_DoE_01.hdf5)

With the exception of a single comprehensive data set comprising unprocessed images (SH2_LS_DoE_01.hdf5), the remaining raw images from all performed measurements can be made available upon request.

B.) Description of Videos.zip:

Example videos for non-structured and laser-structured electrodes at a current density of j = 100 mA/cm² are given for both, sideview and topview. The provided characteristic videos are named after following scheme:

  • Perspective_Electrode_CurrentDensity
  • E.g.: Sideview_#1_NSE_100mAcm-2

Keywords: Alkaline water electrolysis; Bubble dynamics; Direct laser interference patterning; Oxygen evolution reaction

Involved research facilities

  • Data Center

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Permalink: https://www.hzdr.de/publications/Publ-39830


Nuclear magnetic resonance spectroscopy in pulsed magnetic fields

Kühne, H.; Ihara, Y.

Abstract

This article provides an introduction to nuclear magnetic resonance spectroscopy in pulsed magnetic fields (PFNMR), focussing on its capabilities, applications, and future developments in research involving high magnetic fields. It highlights the significance of PFNMR in enhancing the understanding of solid-state materials, with particular emphasis on those exhibiting complex interactions and strong electronic correlations. Several technical aspects are discussed, including the challenges associated with high-frequency NMR experiments. The power of PFNMR is showcased through several examples, including studies on the topical materials LiCuVO4, SrCu2(BO3)2, and CeIn3, offering insights into their magnetic and electronic properties at high magnetic fields. The article also discusses possible future directions for the technique, including improvements in PFNMR instrumentation and the exploration of materials under extreme conditions. This exposition underscores the role of PFNMR in advancing the frontiers of materials-science research.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

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  • Secondary publication expected from 05.09.2025

Permalink: https://www.hzdr.de/publications/Publ-39827


Data publication: Curvature-induced parity loss and hybridization of magnons: Exploring the connection of flat and tubular magnetic shells

Brevis, F.; Landeros, P.; Lindner, J.; Kakay, A.; Körber, L.

Abstract

This archive contains the raw data as well as the Tetrax (www.tetrax.software) Jupyter notebooks to produce the data that has been analyzed and used for the manuscript: Curvature-induced parity loss and hybridization of magnons: Exploring the connection of flat and tubular magnetic shells, Physical Review B 110, 134428 (2024), published on 17 October, 2024.

Keywords: curvature-induced; spin waves; mignons; hybridization; parity

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Permalink: https://www.hzdr.de/publications/Publ-39826


Unusual metallic state in superconducting A15-type La4H23

Guo, J.; Semenok, D.; Shutov, G.; Zhou, D.; Chen, S.; Wang, Y.; Zhang, K.; Wu, W.; Luther, S.; Helm, T.; Huang, X.; Cui, T.

Abstract

Hydride superconductors continue to fascinate the communities of condensed matter physics and material scientists because they host the promising near room-temperature superconductivity. Current research has concentrated on the new hydride superconductors with the enhancement of the superconducting transition temperature (Tc). The multiple extreme conditions (high pressure/temperature and magnetic field) will introduce new insights into hydride superconductors. The study of transport properties under very high magnetic fields facilitates the understanding of superconductivity in conventional hydride superconductors. In the present work, we report experimental evidence of an unusual metal state in a newly synthesized cubic A15-type La4H23 that exhibits superconductivity with a Tc reaching 105 K at 118 GPa. A large negative magnetoresistance is observed in strong pulsed magnetic fields in the non-superconducting state of this compound below 40 K. Moreover, we construct the full magnetic phase diagram of La4H23 up to 68 T at high pressure. The present work reveals anomalous electronic structural properties of A15-La4H23 under high magnetic fields, and therefore has great importance with regard to advancing the understanding of quantum transport behaviors in hydride superconductors.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-39825


Possible realization of a randomness-driven quantum disordered state in the S = 1/2 antiferromagnet Sr3CuTa2O9

Sana, B.; Barik, M.; Lee, S.; Jena, U.; Baenitz, M.; Sichelschmidt, J.; Luther, S.; Kühne, H.; Sethupathi, K.; Ramachandra Rao, M. S.; Choi, K. Y.; Khuntia, P.

Abstract

Collective behavior of spins, frustration-induced strong quantum fluctuations, and subtle interplay between competing degrees of freedom in quantum materials can lead to correlated quantum states with exotic excitations that are essential ingredients for establishing paradigmatic models and have immense potential for quantum technologies. Disorder is ubiquitous in real materials, and the detailed insights into the role of disorder on the intriguing ground state borne out of quenched randomness provide a route towards the design and discovery of functional quantum materials. Herein we report magnetization, specific heat, electron spin resonance, and muon spin resonance studies on a 3d-electron-based antiferromagnet Sr3CuTa2O9. The negative value of Curie-Weiss temperature, obtained from the Curie-Weiss fit of high-temperature magnetic susceptibility data indicates the presence of antiferromagnetic interaction between Cu2+ moments. Specific heat data show the absence of long-range magnetic ordering down to 64 mK despite a reasonably strong exchange interaction between Cu2+ (S = 1/2) spins as reflected from a Curie-Weiss temperature of −27 ± 1 K. The power-law behavior and the data collapse of specific heat and magnetization data evince the emergence of a random-singlet state in Sr3CuTa2O9. The power-law-like spin autocorrelation function and the data collapse of muon polarization asymmetry with longitudinal field dependence of t/(μ0H)γ further support credence to the presence of a randomness-induced quantum disordered state. Our results suggest that randomness induced by disorder is an alternate route to realize quantum spin disordered state in this antiferromagnet.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

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Permalink: https://www.hzdr.de/publications/Publ-39824


Quasistatic magnetism in the breathing pyrochlore antiferromagnets LiGa1−xInxCr4O8 (x = 0.2, 0.5)

Lee, W.; Yoon, S.; Choi, Y.-S.; Do, S.-H.; Ponomaryov, O.; Zvyagin, S.; Gorbunov, D.; Wosnitza, J.; Koda, A.; Chen, W.-T.; Lee, S.

Abstract

We report magnetic susceptibility, high-field magnetization, muon spin relaxation, and electron spin resonance measurements of the breathing pyrochlore antiferromagnets LiGa1−xInxCr4O8 (x = 0.2, 0.5). Unlike the previously proposed spin-glass-like phase for 0.1 < x < 0.75, we find no signature for spin glassiness and phase segregation in both the x = 0.2 and 0.5 compounds. Instead, we identify a two-step magnetic transition with a partial spin freezing at T = 12 K (x = 0.2) and 9 K (x = 0.5) followed by quasistatic order at Tm = 6 K (x = 0.2) and 3 K for (x = 0.5). In addition, for Tm < T < T, we observe evidence of a competition between fast and slow spin dynamics, suggesting a thermal and temporal distribution of spin correlations. Our findings underscore the possibility of realizing novel magnetic phases by tuning bond alternation and introducing bond disorder through chemical substitution.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-39823


Giant magnetocaloric effect of Ni-Co-Mn-Ti all-d Heusler alloys in high magnetic fields

Beckmann, B.; Taubel, A.; Gottschall, T.; Pfeuffer, L.; Koch, D.; Staab, F.; Bruder, E.; Scheibel, F.; Skokov, K. P.; Gutfleisch, O.

Abstract

Ni-Co-Mn-Ti all-d Heusler alloys are attracting considerable attention for solid-state caloric cooling applications due to their promising combination of excellent caloric and mechanical properties. Here, we report on the maximum attainable magnetocaloric effect in Ni37Co13Mn34.5Ti15.5, which shows a first-order magnetostructural martensitic transformation around room temperature. Heat capacity measurements reveal a giant transition entropy change of 43.5 J(kgK)−1 and are utilized to estimate the magnetocaloric effect as well as the magnetic fields required to saturate it in isothermal and adiabatic conditions. Confirming the results based on this approach, we achieve maximum isothermal entropy changes and directly measured adiabatic temperature changes of 37.8 J(kgK)−1 and −20.2 K, respectively. Thus, the herein reported maximum attainable magnetocaloric effect outperforms classical Ni-Mn-based Heusler alloys, such as Ni(-Co)-Mn-In. Especially the saturated adiabatic temperature change surpasses all previously published values of magnetic field-induced first-order phase transitions measured around room temperature in pulsed magnetic fields in recent years. Thereby, we demonstrate that Ni(-Co)-Mn-Ti Heusler alloys are particularly suitable for the application of sufficiently large external stimuli to fully induce the phase transition and exploit their intrinsically large caloric effect.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-39822


Absence of Fermi surface reconstruction in pressure-driven overdoped YBCO

Tozer, S. W.; Coniglio, W. A.; Förster, T.; Bonn, D. A.; Hardy, W. N.; Liang, R.; Kampert, W. A. G.; Grockowiak, A. D.

Abstract

The evolution of the critical superconducting temperature and field, quantum oscillation frequencies, and effective mass m∗ in underdoped YBa2Cu3O7−δ (YBCO) crystals (p = 0.11, with p the hole concentration per Cu atom) points to a partial suppression of the charge orders with increasing pressure up to 7 GPa, mimicking doping. Application of pressures up to 25 GPa pushes the sample to the overdoped side of the superconducting dome. In contrast to other cuprates, or to doping studies on YBCO, the frequencies of the quantum oscillations measured in that pressure range do not support the picture of a Fermi-surface reconstruction in the overdoped regime, but possibly point to the existence of a new charge order.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

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Permalink: https://www.hzdr.de/publications/Publ-39821


Curvature-induced parity loss and hybridization of magnons: Exploring the connection of flat and tubular magnetic shells

Brevis, F.; Landeros, P.; Lindner, J.; Kakay, A.; Körber, L.

Abstract

This paper delves into the connection between flat and curvilinear magnetization dynamics. For this, we numerically study the evolution of the magnon spectrum of rectangular waveguides upon rolling its cross section up to a full tube. Magnon spectra are calculated over a wide range of magnetization states using a finite-element dynamic-matrix method, which allows us to trace the evolution of the magnon frequencies and several critical magnetic fields with increasing curvature. By analyzing the parity of the higher-order magnon modes, we find a curvature-induced mode heterosymmetry that originates from a chiral contribution to the exchange interaction and is related to the Berry phase of magnons in closed loops. Importantly, this curvature-induced parity loss has profound consequences for the linear coupling between different propagating magnons, allowing for hybridization between initially orthogonal modes. In this context, we demonstrate the integral role of edge modes in forming the magnon spectrum in full tubes. Our findings provide theoretical insights into curvilinear magnetization dynamics and are relevant for interpreting and designing experiments in the field.

Keywords: Curvature-induced; parity; hybridization; spin waves

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  • Secondary publication expected from 17.10.2025

Permalink: https://www.hzdr.de/publications/Publ-39818


Fabrication of palladium-enriched metallic structures by direct focused He+ and Ne+ beam nanowriting from organometallic thin films: a com- parison with Ga+ and e− beams

Herrer, L.; Salvador-Porroche, A.; Hlawacek, G.; Cea, P.; María De Teresa, J.

Abstract

A direct nanowriting procedure using helium- and neon-focused ion beams and spin-coated organo-
metallic thin films is introduced and applied to the fabrication of Pd-enriched metallic structures in a
single lithography step. This process presents significant advantages over multi-step resist-based lithogra-
phy and focused beam-induced deposition using gaseous precursors, such as its simplicity and speed,
respectively. The optimized process leads to Pd-rich structures with low electrical resistivity values of 141
and 152 μΩ cm under Ne+ or He+ fluences of 1000 and 5000 μC cm−2, respectively. These resistivity
values correlate well with compositional and microstructural studies, indicating a high Pd metallic content
in a dense structure with a few-nm grain size. The obtained results are compared to similar structures fab-
ricated by direct electron and gallium beam nanowriting, demonstrating the full potential of nanopat-
terned Pd-based organometallic thin films under the most common focused charged beams. The practi-
cal applications of combining spin-coated organometallic thin films with focused beam nanowriting in
micro- and nano-lithography modern procedures are also discussed in this contribution.

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-39806


Focused electron beam induced deposition of magnetic tips for improved magnetic force microscopy

Escalante-Quiceno, A. T.; Fernández, V. V.; Martín, J. I.; Hierro-Rodriguez, A.; Hlawacek, G.; Jaafar, M.; Asenjo, A.; Magén, C.; de Teresa, J. M.

Abstract

The combination of focused electron beam induced deposition (FEBID) and magnetic force microscopy (MFM) has opened up new possibilities in nanoscale magnetic imaging. FEBID offers precise control over the dimensions and magnetic properties of the MFM probes, enabling the development of high-performance magnetic tips with enhanced capabilities compared to conventional ones. These improved tips offer superior resolution, sensitivity, and versatility in nanoscale magnetic surface characterization. Here, we compare the performance of a commercial MFM tip and a FEBID-grown Fe tip in a Ni80Fe20/NdCo5 film. The FEBID tip exhibited superior lateral resolution for topography imaging, likely due to its sharper and well-defined geometry, with a tip diameter of approximately 20 nm. MFM measurements further confirmed this advantage, revealing better-defined magnetic domains and higher magnetic contrast with the FEBID-functionalized probes compared to the commercial tip. This improvement can be attributed to the possibility to optimize the tip-sample magnetic interaction for the FEBID tip. By reducing the lift height of the second pass, we were able to bring the tip closer to the sample, enhancing the magnetic signal without introducing significant topographic artifacts. Overall, these findings highlight the potential of FEBID for creating high-resolution and high-sensitivity MFM tips.

Keywords: Magnetic anisotropy; Magnetic materials; Image processing; Electron beam-induced deposition; Alloys

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Permalink: https://www.hzdr.de/publications/Publ-39804


FLAIM: A reduced volume ignition model for the compression and thermonuclear burn of spherical fuel capsules

Essamade Saufi, A.; Bellenbaum, H.; Read, M.; Niasse, N.; Barrett, S.; Hawker, N.; Joiner, N.; Chapman, D.

Abstract

We present the ‘‘First Light Advanced Ignition Model" (FLAIM), a reduced model for the implosion, adiabatic
compression, volume ignition and thermonuclear burn of a spherical DT fuel capsule utilising a high-Z
metal pusher. FLAIM is characterised by a highly modular structure, which makes it an appropriate tool
for optimisations, sensitivity analyses and parameter scans. One of the key features of the code is the 1D
description of the hydrodynamic operator, which has a minor impact on the computational efficiency, but
allows us to gain a major advantage in terms of physical accuracy. We demonstrate that a more accurate
treatment of the hydrodynamics plays a primary role in closing most of the gap between a simple model and
a general 1D rad-hydro code, and that only a residual part of the discrepancy is attributable to the heat losses.
We present a detailed quantitative comparison between FLAIM and 1D rad-hydro simulations, showing good
agreement over a large parameter space in terms of temporal profiles of key physical quantities, ignition maps
and typical burn metrics.

Permalink: https://www.hzdr.de/publications/Publ-39803


Principal Component Analysis for Distributions Observed by Samples in Bayes Spaces

Pavlú, I.; Machalová, J.; Tolosana Delgado, R.; Hron, K.; Bachmann, K.; van den Boogaart, K. G.

Abstract

Particle or grain size distributions often play an important role in understanding processes in geosciences. Functional data analysis allows applying multivariate methods like principal component analysis directly to such distributions. These are however often observed in the form of samples, and thus with a sampling error. This additional sampling error changes the properties of the multivariate variance and thus the number of relevant principal components and their direction. The result of the principal component analysis becomes an artefact of the sampling error and can negatively affect the following data analysis. This work presents a way of estimating this sampling error and how to confront it in the context of principal component analysis. The effect of the sampling error and the effectiveness of the correction is demonstrated with a series of simulations. It is shown how the interpretability and reproducibility of the principal components improve and become independent of the selection of the basis. The proposed method is then applied on a dataset of grain size distributions in a geometallurgical dataset from Thaba mine in the Bushveld complex.

Keywords: Principal component analysis; Errors in Observations; ZB-splines; Orthogonal ZB-Splines

Permalink: https://www.hzdr.de/publications/Publ-39800


Development and Application of Scalable Density Functional Theory Machine Learning Models

Fiedler, L.

Abstract

Electronic structure simulations allow researchers to compute fundamental properties of materials without the need for experimentation. As such, they routinely aid in propelling scientific advancements across materials science and chemical applications. Over the past decades, density functional theory (DFT) has emerged as the most popular technique for electronic structure simulations, due to its excellent balance between accuracy and computational cost. Yet, pressing societal and technological questions demand solutions for problems of ever-increasing complexity. Even the most efficient DFT implementations are no longer capable of providing answers in an adequate amount of time and with available computational resources. Thus, there is a growing interest in machine learning (ML) based approaches within the electronic structure community, aimed at providing models that replicate the predictive power of DFT at negligible cost. Within this work it will be shown that such ML-DFT approaches, up until now, do not succeed in fully encapsulating the level of electronic structure predictions DFT provides. Based on this assessment, a novel approach to ML-DFT models is presented within this thesis. An exhaustive framework for training ML-DFT models based on a local representation of the electronic structure is developed, including minute treatment of technical issues such as data generation techniques and hyperparameter optimization strategies. Models found via this framework recover the wide array of predictive capabilities of DFT simulations at drastically reduced cost, while retaining DFT levels of accuracy. It is further demonstrated how such models can be used across differently sized atomic systems, phase boundaries and temperature ranges, underlining the general usefulness of this approach.

Keywords: Density Functional Theory; Machine Learning; Surrogate Model

Related publications

  • Doctoral thesis
    TU Dresden, 2024
    Mentor: Prof. Dr. Thomas Cowan, Dr. Attila Cangi
    199 Seiten

Permalink: https://www.hzdr.de/publications/Publ-39797


Ionization potential depression and charge state of warm dense hydrogen from ab initio path integral Monte Carlo simulations

Bellenbaum, H.; Schwalbe, S.; Gawne, T. D.; Vorberger, J.; Fletcher, L.; Böhme, M.; Moldabekov, Z.; Chapman, D.; Doeppner, T.; Bonitz, M.; Dornheim, T.

Abstract

Research into Warm Dense Matter (WDM) has become more important with recent advances in inertial confinement fusion and astrophysics. The interplay between quantum degeneracy and Coulomb interactions, and the transition of condensed and plasma phases occurring under these conditions, however, make WDM extremely difficult to describe theoretically. Several methods exist to describe matter at these conditions, with recent extensions to Path Integral Monte Carlo (PIMC) allowing the calculation of the Laplace transform of the dynamic structure factor, i.e. the imaginary time correlation function (ITCF), of warm dense hydrogen [1]. While PIMC is quasi-exact, it does not give access to other important physical quantities describing a plasma state, like the ionisation and ionisation potential depression (IPD). Moreover, both are difficult to measure experimentally. To remedy this, we instead compare the ITCF from PIMC simulations with synthetic X-Ray Thomson Scattering spectra [2], computed from a Chihara decomposition [3], to obtain a best estimate for the ionisation state. The IPD is then directly calculated using the Saha equation and compared against other commonly used models. We expect this work to be relevant for future inertial confinement energy developments, particularly in validating equation of state models, and for the refinement of astrophysical models.

[1] T. Dornheim et.al., arXiv preprint arXiv:2403.08570 (2024)

[2] T. Dornheim et.al., Phys. Plasmas 30, 042707 (2023)

[3] G. Gregori et.al., Phys. Rev. E 67, 026412 (2003)

  • Lecture (Conference)
    66th Annual Meeting of the APS Division of Plasma Physics, 07.-11.10.2024, Atlanta, USA

Permalink: https://www.hzdr.de/publications/Publ-39790


Evidence of free-bound transitions in warm dense matter and their impact on equation-of-state measurements

Böhme, M.; Fletcher, L.; Doeppner, T.; Kraus, D.; Baczewski, A.; Preston, T.; MacDonald, M.; Graziani, F.; Moldabekov, Z.; Vorberger, J.; Dornheim, T.

Abstract

Warm dense matter (WDM) is now routinely created and probed in laboratories around the world, providing unprecedented insights into conditions achieved in stellar atmospheres, planetary interiors, and inertial confinement fusion experiments. However, the interpretation of these experiments is often filtered through models with systematic errors that are difficult to quantify. Due to the simultaneous presence of quantum degeneracy and thermal excitation, processes in which free electrons are de-excited into thermally unoccupied bound states transferring momentum and energy to a scattered X-ray photon become viable. Here we show that such free-bound transitions are a particular feature of WDM and vanish in the limits of cold and hot temperatures. The inclusion of these processes into the analysis of recent X-ray Thomson Scattering experiments on WDM at the National Ignition Facility and the Linac Coherent Light Source significantly improves model fits, indicating that free-bound transitions have been observed without previously being identified. This interpretation is corroborated by agreement with a recently developed model-free thermometry technique and presents an important step for precisely characterizing and understanding the complex WDM state of matter.

*This work was partly funded by the Center for Advanced Systems Understanding (CASUS) which is financed by Germany's Federal Ministry of Education and Research (BMBF) and by the Saxon Ministry for Science, Culture and Tourism (SMWK) with tax funds on the basis of the budget approved by the Saxon State Parliament.Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy's National Nuclear Security Administration under Contract No. DE-NA0003525.The work of Ti.~D., M.~J.~M, and F.R.G.~was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  • Open Access Logo Lecture (Conference)
    66th Annual Meeting of the APS Division of Plasma Physics, 07.-11.10.2024, Atlanta, USA

Permalink: https://www.hzdr.de/publications/Publ-39789


Towards highly accurate diagnostics of extreme states of matter with x-ray Thomson scattering

Dornheim, T.

Abstract

Matter under extreme densities, temperatures and pressures is ubiquitous throughout our universe
and naturally occurs in a variety of astrophysical objects, including giant planet interiors (e.g.
Jupiter, but also exoplanets), brown dwarfs, white dwarf atmospheres, in the outer layer of neutron
stars and during meteor impacts. On Earth, such extreme states are important for technological
applications such as the discovery and synthesis of novel materials. A particularly important
application is given by inertial fusion energy (IFE), where both the fuel capsule and the ablator
material have to traverse this warm dense matter regime in a controlled way to reach ignition.
Indeed, the recent spectacular news from the National Ignition Facility (NIF) at the Lawrence
Livermore National Laboratory in California, USA, who have reported a net energy gain of the
burning plasma with respect to the compression energy [1], opens up the intriguing possibility to
develop IFE into a clean, safe and nigh abundant source of energy in the future.
In the laboratory, warm dense matter is created in large research facilities such as the European
XFEL in Germany, SACLA in Japan, and the NIF, SLAC, and the OMEGA laser in the USA using a
variety of techniques. Here, a key challenge is given by the accurate diagnostics of the created
samples due to the extreme conditions and the ultrafast time scales. Over the last years, the X-ray
Thomson scattering (XRTS) technique---also known as inelastic X-ray scattering---has emerged as
a promising method of diagnostics as it is, in principle, capable of giving microscopic insights into
the probed sample in the form of the electronic dynamic structure factor [2]. In practice, however,
the interpretation of XRTS measurements has relied on theoretical models that are based on a
number of de-facto uncontrolled assumptions. Consequently, the quality of the thus inferred system
parameters has remained unclear.
Here, I present an overview of a new approach that allows for the model-free interpretation of
XRTS spectra in the imaginary-time domain [3-5]. The latter naturally emerges in Feynman’s
celebrated path integral formulation of statistical mechanics and, by definition, contains the same
information as the usual spectral representation, only in an a-priori unfamiliar representation. At the
same time, working in the imaginary-time allows one to deconvolve the physical information from
effects due to the X-ray source and the detector. This, in turn, opens up the way for the model-free
extraction of important system parameters such as the temperature [3] without the need for any
approximations or simulations.

[1] The Indirect Drive ICF Collaboration, Achievement of Target Gain Larger than Unity in an
Inertial Fusion Experiment, Phys. Rev. Lett. 132, 065102 (2024)
[2] S. H. Glenzer and R. Redmer, X-ray Thomson scattering in high energy density plasmas, Rev.
Mod. Phys. 81, 1625 (2009)
[3] T. Dornheim et al., Accurate temperature diagnostics for matter under extreme conditions,
Nature Commun. 13, 7911 (2022)
[4] T. Dornheim et al., Physical insights from imaginary-time correlation functions, Matt. Radiat.
Extremes 8, 056601 (2023)
[5] T. Dornheim et al., X-ray Thomson scattering absolute intensity from the f-sum rule in the
imaginary-time domain, Sci. Reports 14, 14377 (2024)

  • Invited lecture (Conferences)
    12th International Symposium "Optics & its applications" (OPTICS-12), 15.-19.10.2024, Yerevan, Armenia

Permalink: https://www.hzdr.de/publications/Publ-39788


Ab initio path integral Monte Carlo simulations of warm dense hydrogen

Dornheim, T.

Abstract

Understanding the properties of warm dense hydrogen [1] is of paramount importance for the modeling of astrophysical objects (giant planets, brown dwarfs, etc) and for the development of technological applications such as inertial fusion energy. Yet, the simultaneous presence of Coulomb correlations, partial ionization, quantum degeneracy and strong thermal excitations renders its accurate theoretical description challenging: a holistic approach that takes into account all of these effects without uncontrolled approximations is needed.

Here, I present new ab initio path integral Monte Carlo (PIMC) simulations of warm dense hydrogen [2,3], which have been obtained without the usual fixed-node approximation. While being computationally costly, these simulations give us access to a host of observables, most notably the linear density response and the related local field factors [3]. Finally, I discuss the direct connection between our simulations and upcoming x-ray Thomson scattering (XRTS) experiments with hydrogen, and the potential utility of the static density response function as a physical observable to quantify electronic localization around the ions.

[1] M. Bonitz et al., arXiv:2405.10627

[2] T. Dornheim et al., Journal of Chemical Physics 160, 164111 (2024)

[3] T. Dornheim et al., arXiv:2403.08570

*This work has received funding from the European Union's Just Transition Fund (JTF) within the project "Roentgenlaser-Optimierung der Laserfusion" (ROLF), contract number 5086999001, co-financed by the Saxon state government out of the State budget approved by the Saxon State Parliament.This work has received funding from the European Research Council (ERC) under the European Union’s Horizon 2022 research and innovation programme(Grant agreement No. 101076233, "PREXTREME").Views and opinions expressed are however those of the authors only and do not necessarily reflect those of the European Union or the European Research Council Executive Agency. Neither the European Union nor the granting authority can be held responsible for them

  • Lecture (Conference)
    66th Annual Meeting of the APS Division of Plasma Physics, 07.-11.10.2024, Atlanta, USA

Permalink: https://www.hzdr.de/publications/Publ-39787


Data publication: Real-time 3D Particle Tracking using Ultrafast Electron Beam X-ray Computed Tomography

Windisch, D.; Barthel, F.; Bieberle, A.; Hampel, U.

Abstract

This dataset includes all raw data used in the linked publication "Real-time 3D Particle Tracking using Ultrafast Electron Beam X-ray Computed Tomography".

Keywords: Particle tracking; ultrafast X-ray imaging; real-time control

Involved research facilities

  • ROFEX

Downloads

Permalink: https://www.hzdr.de/publications/Publ-39785


Integration of Python WebApps into the Draco Laser Shot Tracking Pipeline, and Provision of Data and Metadata in the HZDR Data Patchwork

Tippey, K. E.; Knodel, O.; Schlenvoigt, H.; Kluge, T.; Pape, D.; Gruber, T.; Müller, S.; Juckeland, G.

Abstract

The HZDR team has harnessed the power of Python, Flask, Dash, ZeroMQ and Kafka in tandem with MongoDB, to create a suite of web-based applications that simplify the extraction of laser shot data and metadata from various distinct, heterogeneous, semi-automated data acquisition systems.

The Shotsheet apps play a central role in manual logging, especially in a facility with highly flexible but manual operation modes. These apps also connect to other data sources like the Mediawiki ELN system. To enable further automation, we’ve developed the Experimental Shot Counter and enrichment app (escape), which handles incoming ZeroMQ messages from the Draco Laser system (experiment driver) and provides tailored ZeroMQ and Kafka messages within the Lab intranet. These messages can automate the readout and processing of measurements, as well as trigger mechanical actions.

In the subsequent landscape of data management, navigating the diverse array of metadata catalogs – such as SciCat, data publications on Invenio derivatives, and internal archives – presents a formidable challenge. However, with the right strategies, this mosaic of data can be effectively combined and represented to unlock its full potential. In the HZDR data management ecosystem , we delve into the intricacies of data fusion, exploring innovative approaches to seamlessly harmonize metadata catalogs, data publications, and archives.

Keywords: Python; Flask; HZDR

  • Contribution to proceedings
    DAPHNE Annual Meeting 2024, 11.-13.03.2024, Dresden, Germany
    Proceedings of DAPHNE Annual Meeting 2024

Permalink: https://www.hzdr.de/publications/Publ-39784


Multi-section fission ionization chamber for measurement of 239Pu(n,gamma) reaction in fission tagging method

Perkowski, J.; Alcayne, V.; Andrzejewski, J.; Cano-Ott, D.; Gawlik-Ramięga, A.; Mendoza, E.; Sánchez-Caballero, A.; Sibbens, G.; Vanleeuw, D.; Aberle, O.; Altieri, S.; Amaducci, S.; Babiano-Suarez, V.; Bacak, M.; Balibrea Correa, J.; Beltrami, C.; Bennett, S.; Bernardes, A. P.; Berthoumieux, E.; Beyer, R.; Boromiza, M.; Bosnar, D.; Caamaño, M.; Calviño, F.; Calviani, M.; Casanovas, A.; Castelluccio, D. M.; Cerutti, F.; Cescutti, G.; Chasapoglou, S.; Chiaveri, E.; Colombetti, P.; Colonna, N.; Console Camprini, P.; Cortés, G.; Cortés-Giraldo, M. A.; Cosentino, L.; Cristallo, S.; Dellmann, S.; Di Castro, M.; Di Maria, S.; Diakaki, M.; Dietz, M.; Domingo-Pardo, C.; Dressler, R.; Dupont, E.; Durán, I.; Eleme, Z.; Fargier, S.; Fernández, B.; Fernández-Domínguez, B.; Finocchiaro, P.; Fiore, S.; Furman, V.; García-Infantes, F.; Gervino, G.; Gilardoni, S.; González-Romero, E.; Guerrero, C.; Gunsing, F.; Gustavino, C.; Heyse, J.; Hillman, W.; Jenkins, D. G.; Jericha, E.; Junghans, A.; Kadi, Y.; Kaperoni, K.; Kaur, G.; Kimura, A.; Knapová, I.; Kokkoris, M.; Kopatch, Y.; Krtička, M.; Kyritsis, N.; Ladarescu, I.; Lederer-Woods, C.; Lerendegui-Marco, J.; Lerner, G.; Manna, A.; Martínez, T.; Masi, A.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Maugeri, E. A.; Mazzone, A.; Mengoni, A.; Michalopoulou, V.; Milazzo, P. M.; Mucciola, R.; Murtas, F.; Musacchio-Gonzalez, E.; Musumarra, A.; Negret, A.; Pérez de Rada Fiol, A.; Pérez-Maroto, P.; Patronis, N.; Pavón-Rodríguez, J. A.; Pellegriti, M. G.; Petrone, C.; Pirovano, E.; Plaza del Olmo, J.; Pomp, S.; Porras, I.; Praena, J.; Quesada, J. M.; Reifarth, R.; Rochman, D.; Romanets, Y.; Rubbia, C.; Sabaté-Gilarte, M.; Schillebeeckx, P.; Schumann, D.; Sekhar, A.; Smith, A. G.; Sosnin, N. V.; Stamati, M. E.; Sturniolo, A.; Tagliente, G.; Tarifeño-Saldivia, A.; Tarrío, D.; Torres-Sánchez, P.; Vagena, E.; Valenta, S.; Variale, V.; Vaz, P.; Vecchio, G.; Vescovi, D.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Woods, P. J.; Wright, T.; Zarrella, R.; Žugec, P.

Abstract

Abstract: The 239Pu(n,γ) reaction cross section is very important for operation of both thermal and fast reactors, when loaded with MOX fuels. According to the NEA/OECD High Priority Request List the precision of cross section data for this reaction should be improved. The cross section of (n,f) reaction is much higher compared to (n,γ) for this isotope. In such conditions the fission tagging technique could be applied to identify the fission background. In the past, this technique was successfully used for capture measurements at the n_TOF facility at CERN. The multi-section fission ionization chamber was constructed and used in the combination with Total Absorption Calorimeter (TAC) for detecting gamma rays for the precise measurement of 239Pu(n,γ) reaction cross section at the n_TOF facility.

Keywords: Radiative neutron capture cross section; Fission Ionization chamber; 239Pu; n_TOF facility; CERN

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Permalink: https://www.hzdr.de/publications/Publ-39782


UAV and field hyperspectral imaging for Sphagnum discrimination and vegetation modelling in Finnish aapa mires

Wolff, F.; Lorenz, S.; Korpelainen, P.; Eltner, A.; Kumpula, T.

Abstract

Detailed knowledge of vegetation patterns allows to evaluate mire ecosystems and their dynamics. The use of hyperspectral information has the benefits of exploring spectral characteristics of species and vegetation modelling. Our study employed multi-scale and multi-source hyperspectral imaging with a handheld camera in the field and an UAV (Unoccupied Aerial Vehicle) sensor covering the wavelengths of 400 – 1000 nm. Plot-level spectra acquired with a UAV and field spectra collected at 1 m height were combined to develop a spectral library for Sphagnum moss species. This library was then used to map dominant Sphagnum species in a Finnish Aapa mire complex using the Spectral Angle Mapper (SAM) classifier. Classification performance assessment was supported by calculating a water index from the UAV-information. Additionally, we examined the transferability of site-specific spectral libraries to an aapa mire with similar vegetation. The results showed little spectral variation in the plot spectrum between the sensors. A fusion of species- and plot-level libraries yielded the highest accuracy of 62 %. For both mires, there was a great variation among the class accuracies. Floating mosses had an accuracy of 86 %, followed by lawn-forming Sphagnum balticum with 77 %. For the test site, the latter species was mapped with an accuracy of 59 %. Red moss species achieved low accuracies of 45 % and 38 %, likely due to effects from sub-pixel and mixed-pixel effects of neighbouring graminoid species and the presence of litter. This might have also enhanced the contrast of adjacent pixels contributing to spectral alterations. Water table depth measurements and the water index revealed a hydrological preference for most species, with classification performance notably improving with higher water index values. We recommend collecting on-site hyperspectral information at varying hydrological circumstances to build a comprehensive spectral library for mire vegetation and modelling.

Permalink: https://www.hzdr.de/publications/Publ-39779


Relaxation to persistent currents in a Hubbard trimer coupled to fermionic baths

Szpak, N.; Schaller, G.; Schützhold, R.; König, J.

Abstract

We consider a ring of fermionic quantum sites, modeled by the Fermi-Hubbard Hamiltonian, in which electrons can move and interact strongly via the Coulomb repulsion. The system is coupled to fermionic cold baths, which by the exchange of particles and energy induce relaxation in the system. We eliminate the
environment and describe the system effectively by Lindblad master equations in various versions valid for different coupling parameter regimes. The early relaxation phase proceeds in a universal way, irrespective of the relative couplings and approximations. The system settles down to its low-energy sector and is consecutively well approximated by the Heisenberg model. We compare different Lindblad approaches, which, in the late relaxation, push the system towards different final states with opposite, extreme spin orders, from ferromagenetic to antiferromagnetic. Due to spin frustration in the trimer (a three site ring), degenerate ground states are formed by spin waves (magnons). The system described by the global coherent version of the Lindblad operators relaxes
towards the final states carrying directed persistent spin currents. We numerically confirm these predictions.

Keywords: Lindblad equation; Fermi-Hubbard Hamiltonian; relaxation dynamics; Heisenberg model; coherent approximation

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Permalink: https://www.hzdr.de/publications/Publ-39778


Julia in high-energy physics: A paradigm shift or just another tool?

Hernandez Acosta, U.

Abstract

The Julia programming language was designed for scientific computing and with its claimed usability („walks like Python“) and speed („runs like C“), it seems to be a scientists‘ software dream come true. Julia appears to be particularly well-suited for high-energy physics (HEP), where reliable software tools and rapid development cycles are crucial for everyday work. Whether it’s data processing, or the simulation of the whole experiment, or the final data analysis and interactive visualization, the Julia ecosystem — with over ten thousand packages — might be a modern and high-performance software solution and the right set of tools to easily build any missing pieces.
In this talk, we will discuss, if the Julia programming language meets these requirements and can withstand testing on the workbenches of HEP. Additionally, we give an overview of current contributions in Julia to the HEP-related software stack and its potential trajectory. Moreover, we explore how the software development process itself can benefit from Julia, as it strikes an ideal balance between high-performance technology and student-friendly training — an especially valuable combination for the rapidly moving high-energy physics community.

Keywords: Julia Programming Language; High-Energy Physics; HPC

  • Open Access Logo Invited lecture (Conferences)
    JuliaHEP 2024 Workshop, 30.09.-04.10.2024, CERN, Switzerland

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Permalink: https://www.hzdr.de/publications/Publ-39776


IntegrationTests.jl: a framework for the automatic generation of integration tests for Julia projects and eco systems

Ehrig, S.; Hernandez Acosta, U.; Reinhard, A.

Abstract

To be successor, every larger software project needs to be tested to verify the correct functionality and to enable its functionality to be extended flawlessly. The type of tests can be very different and depends on the kind of software project. Software projects, that are divided into several sub-projects require integration tests to verify that the individual parts work together correctly.
At JuliaHEP 2023, I gave the talk “Unit and Integration testing in modularized julia package eco-systems” and talked about the problems that need to be solved when developing integration tests for a Julia package ecosystem. With the feedback from the talk, I developed IntegrationTests.jl [1], a framework to dynamically generate GitHub Action or GitLab CI integration jobs for a given Julia Project.toml. The talk explains the different problems to solve when adding integration tests in a Julia project and how IntegrationTests.jl solves them.

[1] https://github.com/QEDjl-project/IntegrationTests.jl

Keywords: QED; Automatic testing; Integration tests; Julia; JuliaHEP

  • Open Access Logo Lecture (Conference)
    JuliaHEP 2024 Workshop, 30.09.-04.10.2024, CERN, Schweiz

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Permalink: https://www.hzdr.de/publications/Publ-39775


Generating Feynman Diagrams for QED in Julia

Reinhard, A.; Hernandez Acosta, U.; Ehrig, S.

Abstract

Calculating differential cross-sections of scattering processes is a crucial observable in high-energy physics, used to predict experimental outcomes and test theoretical models. For perturbative quantum field theories, this involves generating all possible Feynman diagrams for a given scattering process and translating them into computable functions. This becomes cumbersome very rapidly, especially for high-multiplicity processes. In this talk, we introduce a method implemented in Julia for generating these functions for arbitrary scattering processes in perturbative QED, utilizing the ComputableDAGs.jl library. Our approach incorporates novel results and reuse optimizations, which could be extended to other theories or even the entire Standard Model and beyond.

Keywords: Julia; HPC; Feynman; QED; Diagrams; DAG; scattering

  • Open Access Logo Lecture (Conference)
    JuliaHEP 2024 Workshop, 30.09.-04.10.2024, Genf, Schweiz

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Permalink: https://www.hzdr.de/publications/Publ-39773


CT image sequences of sandwich packings: B1-250 plus B1-750 at constant liquid rate of 50 m³/(m²h) and various gas rates

Sohr, J.; Barthel, F.; Sprewitz, U.; Schubert, M.
Producer: Barthel, Frank; DataManager: Sprewitz, Uwe; Researcher: Sohr, Johanna; Project Leader: Schubert, Markus; DataCurator: Bieberle, André

Abstract

This repository contains sequences of CT images of the two-phase flow in sandwich packings that are alternately arranged in a packing stack using B1-250 (specific geometric surface area is 250 m² /m³) for de-entrainment layer and B1-750 (specific geometric surface area is 750 m² /m³) for holdup layer. As measurement system the ultrafast electron beam X-ray computed tomography scanner was applied in dual plane scanning mode with a dual-imaging frequency of 1000 Hz. Operating parameters, the scanning plane as well as the tags "AB" for de-entrainment layer, "AN" for hold-up layer and "DRIVE" for an axial scan are encoded in the name of the data files.

Keywords: sandwich packings; two-phase flow; ultrafast electron-beam X-ray CT

Involved research facilities

  • TOPFLOW Facility
  • ROFEX

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Permalink: https://www.hzdr.de/publications/Publ-39769


CT image sequences of sandwich packings: B1-250 plus B1-750 at constant liquid rate of 20 m³/(m²h) and various gas rates

Sohr, J.; Barthel, F.; Sprewitz, U.; Schubert, M.
Producer: Barthel, Frank; DataManager: Sprewitz, Uwe; Researcher: Sohr, Johanna; Project Leader: Schubert, Markus; DataCurator: Bieberle, André

Abstract

This repository contains sequences of CT images of the two-phase flow in sandwich packings that are alternately arranged in a packing stack using B1-250 (specific geometric surface area is 250 m² /m³) for de-entrainment layer and B1-750 (specific geometric surface area is 750 m² /m³) for holdup layer. As measurement system the ultrafast electron beam X-ray computed tomography scanner was applied in dual plane scanning mode with a dual-imaging frequency of 1000 Hz. Operating parameters, the scanning plane as well as the tags "AB" for de-entrainment layer, "AN" for hold-up layer and "DRIVE" for an axial scan are encoded in the name of the data files.

Keywords: sandwich packings; two-phase flow; ultrafast electron-beam X-ray CT

Involved research facilities

  • TOPFLOW Facility
  • ROFEX

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Permalink: https://www.hzdr.de/publications/Publ-39768


Structural and Compositional Optimization of Bimetallic NiCo Nanoalloys for Promotion of Alkaline Hydrogen Evolution Reaction

Mohanty, B.; Pradhan, L.; Satpati, B.; Rajput, P.; Ghorbani Asl, M.; Wei, Y.; Menezes, P. W.; Krasheninnikov, A.; Kumar Jenaa., B.

Abstract

Alkaline hydrogen evolution reaction (HER) is highly desired due to its economic utility as well as its basic significance in the study of all electrocatalytic processes taking place on cathode electrodes. Herein, we report the nickel and cobalt-based bimetallic alloy nanoparticles embedded in nitrogen-doped carbon (NiₓCo₁₋ₓ@NC) starting from novel metal-organic complexes. Among the synthesized alloy nanoparticle catalysts, Ni₁Co₃@NC exhibits the best performance for HER, reaching a current density of 10 mA/cm² merely at an overpotential of 28 mV, outperforming state-of-the-art noble Pt-based, as well as non-noble metal-based catalysts. Remarkably, this catalyst displays a high turnover frequency (TOF) of 32.44 s⁻¹ and even long-term durability at higher current density (50 mA/cm²) up to 175 hours with negligible decay. A series of advanced characterizations reveal that Ni₁Co₃@NC undergoes minimal near-surface restructuring, majorly retaining its structure during longer operations. In order to comprehend the interaction between the inherent HER activity and the metal center, we conducted further experiments for several bimetallic alloy nanoparticles by alloying Co nanoparticles with Mn, Fe, and Zn. This work sheds important light on the structure-function link for bimetallic alloy nanoparticles made of non-noble metals that exhibit electrocatalytic HER activity in an alkaline medium.

Keywords: Bimetallic alloy nanoparticles; NiCo; Alkaline solutions; Hydrogen evolution reaction; Improved hydrogen adsorption

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-39767


CT image sequences of sandwich packings: B1-250 plus B1-750 at constant liquid rate of 10 m³/(m²h) and various gas rates

Sohr, J.; Barthel, F.; Sprewitz, U.; Schubert, M.
Producer: Barthel, Frank; DataManager: Sprewitz, Uwe; Researcher: Sohr, Johanna; Project Leader: Schubert, Markus; DataCurator: Bieberle, André

Abstract
This repository contains sequences of CT images of the two-phase flow in sandwich packings that are alternately arranged in a packing stack using B1-250 (specific geometric surface area is 250 m² /m³) for de-entrainment layer and B1-750 (specific geometric surface area is 750 m² /m³) for holdup layer. As measurement system the ultrafast electron beam X-ray computed tomography scanner was applied in dual plane scanning mode with a dual-imaging frequency of 1000 Hz. Operating parameters, the scanning plane as well as the tags "AB" for de-entrainment layer, "AN" for hold-up layer and "DRIVE" for an axial scan are encoded in the name of the data files.

Keywords: sandwich packings; two-phase flow; ultrafast electron-beam X-ray CT

Involved research facilities

  • TOPFLOW Facility
  • ROFEX

Downloads

Permalink: https://www.hzdr.de/publications/Publ-39766


Setting reaction of a olivine-based Mg-phosphate cement

Bernasconi, D.; Viani, A.; Zárybnická, L.; Bordignon, S.; da Assuncao Godinho, J. R.; Maximenko, A.; Celikutku, C.; Jafri, S. F.; Borfecchia, E.; Wehrung, Q.; Gobetto, R.; Pavese, A.

Abstract

The cementitious properties of natural Mg-rich olivine when reacted with a phosphoric acid solution are investigated, as a function of acid concentration and liquid/solid mass ratio. The obtained cements are composed of residual olivine crystals and amorphous silica nanoparticles dispersed in a dense and compact newberyite (MgHPO4∙3H2O) matrix. The latter was mostly formed by packed micrometric tabular crystals, although evidence of the presence of a fraction of amorphous MgHPO4 was also found. Water content in the raw mix was observed to play a pivotal role on the reaction pathway, either promoting porosity or hindering the crystallization of the products. Up to 57 % of olivine reactivity, whose dissolution was promoted by the curing temperature (60 °C) and low pH, was achieved. All in all, these results indicate that the industrial mineral olivine may serve a viable source of Mg for the production of phosphate cements.

Keywords: Phosphate cement; Magnesium cement; Olivine; Alternative binders

Permalink: https://www.hzdr.de/publications/Publ-39763


Comprehensive Synthesis and Structural Trends in Tetramethyl Diglycolamide (TMDGA) Nitrate Complexes with Lanthanides and Americium

Rotermund, B. M.; Beck, N. B.; Sperling, J. M.; Horne, G. P.; Huffman, Z. K.; Grödler, D.; Albrecht, T. E.

Abstract

Complexes of N,N,N′,N′-tetramethyl diglycolamide (TMDGA), a hydrophilic diglycolamide (DGA) proposed as an aqueous phase holdback reagent, have been crystallizedfor the majority of the lanthanide series (excluding promethium), yttrium, and americium to deepen our structural understanding of trivalent metal ion (M³⁺) DGA coordination compounds in the presence of nitrate counter-anions. The presented collection of 16 complexes with accompanying single-crystal structures, taking formulas M(TMDGA)₃][M(NO₃)₆] (M = La, Ce, Pr, Nd, Sm, Am), [M(TMDGA)₃][M(NO₃)₅(H₂O)]₁₋ₓ[M(NO₃)₄(H₂O)₂]ₓ(NO₃)₁₊ₓ (M = Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb), [M(TMDGA)₃]₂[M(NO₃)₄(H₂O)₂]₀.₇₅[M(NO₃)₅(H₂O)]₁.₂₅(NO₃)₂.₇₅·H₂O (M = Lu), and [M(TMDGA)₃][M(NO₃)₅(H₂O); whereas the remaining smaller lanthanides did not possess sufficiently large ionic radii to coordinate six bidentate nitrate anions, instead, one or two nitrate anions are situated in the outer sphere. The systematic progression of changes in the anionic environments of these complexes outlines the changing coordination habits afforded by the lanthanide contraction.

Permalink: https://www.hzdr.de/publications/Publ-39761


Dynamic convergent shock compression initiated by return current in high-intensity laser–solid interactions

Yang, L.; Rehwald, M.; Kluge, T.; Laso García, A.; Toncian, T.; Zeil, K.; Schramm, U.; Cowan, T.; Huang, L.

Abstract

We investigate the dynamics of convergent shock compression in solid cylindrical targets irradiated by an ultrafast relativistic laser pulse. Our particle-in-cell simulations and coupled hydrodynamic simulations reveal that the compression process is initiated by both magnetic pressure and surface ablation associated with a strong transient surface return current with density of the order of 1017 A/m2 and lifetime of 100 fs. The results show that the dominant compression mechanism is governed by the plasma β, i.e., the ratio of thermal pressure to magnetic pressure. For targets with small radius and low atomic number Z, the magnetic pressure is the dominant shock compression mechanism. According to a scaling law, as the target radius and Z increase, the surface ablation pressure becomes the main mechanism generating convergent shocks. Furthermore, an indirect experimental indication of shocked hydrogen compression is provided by optical shadowgraphy measurements of the evolution of the plasma expansion diameter. The results presented here provide a novel basis for the generation of extremely high pressures exceeding Gbar (100 TPa) to enable the investigation of high-pressure physics using femtosecond J-level laser pulses, offering an alternative to nanosecond kJ-laser pulse-driven and pulsed power Z-pinch compression methods.

Involved research facilities

  • HIBEF
  • Draco

Permalink: https://www.hzdr.de/publications/Publ-39759


Variable-RBE-induced NTCP predictions for various side-effects following proton therapy for brain tumors – Identification of high-risk patients and risk mitigation

Palkowitsch, M.; Kaufmann, L.-M.; Hennings, F.; Menkel, S.; Hahn, C.; Bensberg, J.; Lühr, A.; Seidlitz, A.; Troost, E. G. C.; Krause, M.; Löck, S.

Abstract

Background and purpose
Disregarding the increase of relative biological effectiveness (RBE) may raise the risk of acute and late adverse events after proton beam therapy (PBT). This study aims to explore the relationship between variable RBE (above 1.1)-induced normal tissue complication probabilities (NTCP) and patient-specific factors, identify patients at high risk of RBE-induced NTCP increase, and assess risk mitigation by incorporating RBE variability into treatment planning.
Materials and methods
We retrospectively analyzed 105 primary brain tumor patients treated with PBT (RBE=1.1). We calculated differences in estimated NTCP (ΔNTCP) using a variable RBE-weighted dose (DRBE, Wedenberg model) and a constant RBE-weighted dose (DRBE=1.1), across 16 NTCP models. These differences were correlated with patient-specific characteristics. Based on ΔNTCP, patients were classified as high risk (32%) or low risk (68%) for adverse events due to RBE-induced NTCP. This classification was compared with alternative classifications based on (a) relevant patient-specific characteristics, (b) DRBE=1.1, and (c) the difference between DRBE and DRBE=1.1 (ΔD), assessing the balanced accuracy. The potential to reduce RBE-induced NTCP through track-end and linear energy transfer (LET) optimization was evaluated in six example patients.
Results
Using a variable RBE instead of a constant one resulted in NTCP increases (up to 32 percentage points). Variable-RBE-induced NTCP increases were strongly negatively correlated with the distance between the clinical target volume (CTV) and the organ at risk (OAR) for most side-effects, and positively correlated with CTV volume for certain side-effects. High increases were associated with (a) specific patient factors, particularly the proximity of the CTV to OARs, (b) DRBE=1.1, and (c) ΔD, with a balanced accuracy of 0.88, 0.94, and 0.86, respectively. Optimization of track-ends and LET considerably reduced NTCP values, achieving a mean reduction of 31% for optimized OARs.
Conclusion
The risk of variable-RBE-induced NTCP strongly depends on patient-specific factors and the considered side-effect. A small distance between the tumor and OARs notably increases the risk. Integrating biologically-guided objectives into treatment planning can effectively mitigate the risk.

Keywords: Proton beam therapy (PBT); Relative Biological Effectiveness (RBE); Linear Energy Transfer (LET); Normal Tissue Complication Probability (NTCP); Treatment plan optimization

Involved research facilities

  • OncoRay

Permalink: https://www.hzdr.de/publications/Publ-39756


Calculations and Measurements of the Neutron Fluence outside the RPV for the Decommissioning of a PWR

Rachamin, R.; Konheiser, J.; Barkleit, A.; Nikitin, E.; Seidl, M.

Abstract

Determining the neutron activation in the single components is an important task in the
decommissioning process of NPPs. Therefore, neutron fluences are the most fundamental and important
parameter on which every decommissioning planning is based. The aim of this study is to estimate this
accurately using Monte Carlo simulations. A detailed 3D model of a PWR was developed, and the
neutron fluence was calculated and validated based on metal foil-activation measurements.

Keywords: PWR; Decommissioning; Neutron fluence; Monte Carlo; Activation foils

  • Contribution to proceedings
    GLOBAL 2024 International Conference on Nuclear Fuel Cycle, 06.10.2024, Tokyo, Japan
  • Poster
    GLOBAL 2024 International Conference on Nuclear Fuel Cycle, 07.10.2024, Tokyo, Japan

Permalink: https://www.hzdr.de/publications/Publ-39752


Direct evidence for ligand-enhanced activity of Cu(I) sites

Gouatieu Dongmo, E.; Haque, S.; Kreuter, F.; Wulf, T.; Jin, J.; Tonner-Zech, R.; Heine, T.; Asmis, K. R.

Abstract

The dataset consists of Infrared photodissociation (IRPD) spectra of Cu+(H2O)(H2)n (with n ≤ 3) and its isotopologue measured on the Leipzig 5 K ring-electrode ion-trap triple mass spectrometer. Besides, it contains the Energy Decomposition Analysis (EDA), the benchmark results, the harmonic and the anharmonic VPT2 frequencies results as well as the script used to get the predicted separation factor for the adsorbed dihydrogen isotopologue. HoFe₆Al₆

Keywords: adsorption; dihydrogen isotopologue; anharmonicity; selectivity; Python

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Permalink: https://www.hzdr.de/publications/Publ-39751


Development and application of Serpent/DYN3D/ATHLET code system for SFR safety analysis

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

Abstract

The paper presents the current status and recent applications of the Serpent/DYN3D/ATHLET code system to various Sodium-cooled Fast Reactor (SFR) designs. It emphasizes the system’s capability for coupled DYN3D and ATHLET transient simulations that account for all significant reactivity effects inherent to SFR, in particular those related to thermal expansion of core and primary system structural elements. Recent applications to transient analysis across SFRs of various sizes and power outputs demonstrates robustness of the implemented approaches and provides a solid validation basis for the developed methodology.

Keywords: SFR; safety analysis; Unprotected-Loss-Of-Flow; coupled neutronic/thermal hydraulic simulation; spatial kinetics; core thermal expansion

  • Contribution to proceedings
    GLOBAL 2024 International Conference on Nuclear Fuel Cycle, 06.10.2024, Tokyo, Japan
  • Lecture (Conference)
    GLOBAL 2024 International Conference on Nuclear Fuel Cycle, 08.10.2024, Tokyo, Japan

Permalink: https://www.hzdr.de/publications/Publ-39750


Growth of Ba2CoWO6 single crystals and their magnetic, thermodynamic and electronic properties

Hanna, A. R. N.; Islam, A. T. M. N.; Ritter, C.; Luther, S.; Feyerherm, R.; Lake, B.

Abstract

This study explores the bulk crystal growth, structural characterization, and physical property measurements of the cubic double perovskite Ba2CoWO6 (BCWO). In BCWO, Co2+ ions form a face-centred cubic lattice with non-distorted cobalt octahedra. The compound exhibits long-range antiferromagnetic order below TN = 14 K. Magnetization data indicated a slight anisotropy along with a spin-flop transition at 10 kOe, a saturation field of 310 kOe and an ordered moment of 2.17 μB at T = 1.6 K. Heat capacity measurements indicate an effective j = 1/2 ground state configuration, resulting from the combined effects of the crystal electric field and spin-orbit interaction. Surface photovoltage analysis reveals two optical gaps in the UV–Visible region, suggesting potential applications in photocatalysis and photovoltaics. The magnetic and optical properties highlight the significant role of orbital contributions within BCWO, indicating various other potential applications.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-39748


Dramatic elastic response at the critical end point in UTe2

Valiska, M.; Haidamak, T.; Cabala, A.; Pospisil, J.; Bastien, G.; Sechovsky, V.; Prokleska, J.; Yanagisawa, T.; Opletal, P.; Sakai, H.; Haga, Y.; Miyata, A.; Gorbunov, D.; Zherlitsyn, S.

Abstract

The first-order transition line in the H-T phase diagram of itinerant electron metamagnets terminates at the critical end point—analogous to the critical point on the gas-liquid condensation line in the p-T phase diagram. To unravel the impact of critical magnetic fluctuations on the crystal lattice of a metamagnet at the critical end point, we performed an ultrasonic study of the itinerant electron metamagnet UTe2 across varying temperatures and magnetic fields. At temperatures exceeding 9 K, a distinct V-shaped anomaly emerges, precisely centered at the critical field of the metamagnetic transition in the isothermal field dependence of elastic constants. This anomaly arises from lattice instability, triggered by critical magnetic fluctuations via strong magnetoelastic interactions. Remarkably, this effect is maximized precisely at the critical-end-point temperature. Comparative measurements of another itinerant metamagnet, UCoAl, reveal intriguing commonalities. Despite significant differences in the paramagnetic ground state, lattice symmetry, and the expected metamagnetic transition process between UTe2 and UCoAl, both exhibit similar anomalies in elastic properties near the critical end point.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-39747


Giant magnetocaloric effect in a rare-earth-free layered coordination polymer at liquid hydrogen temperatures

Levinsky, J. J. B.; Beckmann, B.; Gottschall, T.; Koch, D.; Ahmadi, M.; Gutfleisch, O.; Blacke, G. R.

Abstract

Magnetic refrigeration, which utilizes the magnetocaloric effect, can provide a viable alternative to the ubiquitous vapor compression or Joule-Thompson expansion methods of refrigeration. For applications such as hydrogen gas liquefaction, the development of magnetocaloric materials that perform well in moderate magnetic fields without using rare-earth elements is highly desirable. Here we present a thorough investigation of the structural and magnetocaloric properties of a novel layered organic-inorganic hybrid coordination polymer Co4(OH)6(SO4)2[enH2] (enH2 = ethylenediammonium). Heat capacity, magnetometry and direct adiabatic temperature change measurements using pulsed magnetic fields reveal a field-dependent ferromagnetic second-order phase transition at 10 K < TC < 15 K. Near the hydrogen liquefaction temperature and in a magnetic field change of 1 T, a large maximum value of the magnetic entropy change, ΔSPk M = − 6.31 J kg−1 K−1, and an adiabatic temperature change, ΔTad = 1.98K, areobserved. These values are exceptional for rare-earth-free materials and competitive with many rare-earth-containing alloys that have been proposed for magnetic cooling around the hydrogen liquefaction range.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-39746


Interface Dependent Coexistence of Two-Dimensional Electron and Hole Gases in Mn-doped InAs/GaSb

Riney, L.; Bac, S.-K.; Zhukovskyi, M.; Orlova, T.; Fields, S. S.; Wang, J.; Kotte, T.; Graf, D.; Bennett, S. P.; Liu, X.; Assaf, B. A.

Abstract

The interface of common III-V semiconductors InAs and GaSb can be utilized to realize a two-dimensional (2D) topological insulator state. The 2D electronic gas at this interface can yield Hall quantization from coexisting electrons and holes. This anomaly is a determining factor in the fundamental origin of the topological state in InAs/GaSb. Here, the coexistence of electrons and holes in InAs/GaSb is tied to the chemical sharpness of the interface. Magnetotransport, in samples of Mn-doped InAs/GaSb cleaved from wafers grown at a spatially inhomogeneous substrate temperature, is studied. It is reported that the observation of quantum oscillations and a quantized Hall effect whose behavior, exhibiting coexisting electrons and holes, is tuned by this spatial nonuniformity. Through transmission electron microscopy measurements, it is additionally found that samples that host this co-existence exhibit a chemical intermixing between group III and group V atoms that extends over a larger thickness about the interface. The issue of intermixing at the interface is systematically overlooked in electronic transport studies of topological InAs/GaSb. These findings address this gap in knowledge and shed important light on the origin of the anomalous behavior of quantum oscillations seen in this 2D topological insulator.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-39745


Structural Regulation of Au-Pt Bimetallic Aerogels for Catalyzing the Glucose Cascade Reaction

Wang, C.; Wang, L.; Nallathambi, V.; Liu, Y.; Kresse, J.; Hübner, R.; Reichenberger, S.; Gault, B.; Zhan, J.; Eychmüller, A.; Cai, B.

Abstract

Bimetallic nanostructures are promising candidates for the development of enzyme-mimics, yet the deciphering of the structural impact on their catalytic properties poses significant challenges. By leveraging the structural versatility of nanocrystal aerogels, this study reports a precise control of Au-Pt bimetallic structures in three representative structural configurations, including segregated, alloy, and core-shell structures. Benefiting from a synergistic effect, these bimetallic aerogels demonstrate improved peroxidase- and glucose oxidase-like catalytic performances compared to their monometallic counterparts, unleashing tremendous potential in catalyzing the glucose cascade reaction. Notably, the segregated Au-Pt aerogel shows optimal catalytic activity, which is 2.80 and 3.35 times higher than that of the alloy and core-shell variants, respectively. This enhanced activity is attributed to the high-density Au-Pt interface boundaries within the segregated structure, which foster greater substrate affinity and superior catalytic efficiency. This work not only sheds light on the structure-property relationship of bimetallic catalysts but also broadens the application scope of aerogels in biosensing and biological detections.

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Permalink: https://www.hzdr.de/publications/Publ-39744


Data publication: Simulation results on Aminophenyl Viologen

Mitrofanov, A.; Dreimann, O.; Zakirova, K.; Waentig, A. L.; Wrzesińska-Lashkova, A.; Kuc, A. B.; Ruck, M.; Vaynzof, Y.; Feng, X.; Voit, B.

Abstract

Structural and electronic properties simulated using DFT/PBE level of theory with TS dispersion correction as implemented in FHI-Aims code.

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Permalink: https://www.hzdr.de/publications/Publ-39743


Paratellurite Nanowires as a Versatile Material for THz Phonon Polaritons

Mayer, R. A.; Wehmeier, L.; Torquato, M.; Chen, X.; Feres, F. H.; Maia, F. C. B.; Obst, M.; Kaps, F. G.; Luferau, A.; Klopf, J. M.; Gilbert Corder, S. N.; Bechtel, H. A.; González, J. C.; Viana, E. R.; Eng, L. M.; Kehr, S. C.; Freitas, R. O.; Barcelos, I. D.

Abstract

Polaritons, i.e., hybrid quasi-particles of light and matter resonances, have been extensively investigated due to their potential to enhance light–matter interactions. Although polaritonic applications thrive in the mid-infrared range, their extension to the terahertz (THz) range remains limited. Here, we present paratellurite (α-TeO2) nanowires, a versatile material acting as a platform for different types of phonon polaritons. Utilizing synchrotron infrared nanospectroscopy from 10 to 24 THz, we uncover the polaritonic properties of α-TeO2 nanowires, showcasing their dual functionality as both a Fabry–Pérot cavity and a waveguide for surface phonon polaritons. Furthermore, near-field measurements with a free-electron laser as a THz source reveal a localized optical contrast down to 5.5 THz, an indication of hyperbolic bands. Our findings complement the repertoire of polaritonic materials, with significant implications for advancing THz technologies.

Keywords: s-SNOM; FEL; THz; near-field; polariton; nanoscopy; phonons

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  • Secondary publication expected from 20.09.2025

Permalink: https://www.hzdr.de/publications/Publ-39742


Ultrafast switching of trions in 2D materials by terahertz photons

Venanzi., T.; Cuccu, M.; Perea-Causin, R.; Sun, X.; Samuel, B.; Erkensten, D.; Taniguchi., T.; Watanabe., K.; Malic., E.; Helm, M.; Winnerl, S.; Chernikovon, A.

Abstract

External control of optical excitations is key for manipulating light–matter coupling and is highly desirable for photonic technologies. Excitons in monolayer semiconductors emerged as a unique nanoscale platform in this context, offering strong light–matter coupling, spin–valley locking and exceptional tunability. Crucially, they allow electrical switching of their
optical response due to efficient interactions of excitonic emitters with free charge carriers, forming new quasiparticles known as trions and Fermi polarons. However, there are major limitations to how fast the light emission of these states can be tuned, restricting the majority of applications to an essentially static regime. Here we demonstrate switching of excitonic light
emitters in monolayer semiconductors on ultrafast picosecond time scales by applying short pulses in the terahertz spectral range following optical injection. The process is based on a rapid conversion of trions to excitons by absorption of terahertz photons inducing photo detachment. Monitoring time-resolved emission dynamics in optical-pump/terahertz-push
experiments, we achieve the required resonance conditions as well as demonstrate tunability of the process with delay time and terahertz pulse power. Our results introduce a versatile experimental tool for fundamental research of light-emitting excitations of composite Bose–Fermi mixtures and open up pathways towards technological developments of new types of nanophotonic device based on atomically thin materials.

Involved research facilities

  • F-ELBE

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  • Secondary publication expected from 23.09.2025

Permalink: https://www.hzdr.de/publications/Publ-39741


Curvilinear magnetism: fundamentals and applications

Makarov, D.

Abstract

Curvilinear magnetism is a framework, which helps understanding the impact of geometric curvature on complex magnetic responses of curved 1D wires and 2D shells [1-3]. This approach provides means to modify conventional or to launch novel functionalities by tailoring curvature and 3D shape of magnetic thin films and nanowires [3]. In this talk, we will address fundamentals of curvature-induced effects in magnetism and review the envisioned application scenarios. In particular, we will demonstrate that curvature allows tailoring fundamental anisotropic and chiral magnetic interactions and enables fundamentally new nonlocal chiral symmetry breaking effect [4]. The topology of the geometry of 3D shaped magnetic objects allows stabilizing multiple solitons within a confined nanoarchitecture [5]. Those are relevant for numerous research and technology fields ranging from non-conventional computing and spin-wave splitters for low-energy magnonics. The application potential of geometrically curved magnetic architectures is being explored as mechanically reshapeable magnetic field sensors for automotive applications, spin-wave filters, high-speed racetrack memory devices, magnetic soft robots [6] as well as on-skin interactive electronics relying on thin films [7-9] as well as printed magnetic composites [10,11] with appealing self-healing performance [12]. This opens perspectives for magnetoelectronics in smart wearables, interactive printed electronics and motivates further explorations towards the realization of eco-sustainable magnetic field sensing relying on biocompatible and biodegradable materials [13-15].

[1] P. Gentile et al., Electronic materials with nanoscale curved geometries. Nature Electronics (Review) 5, 551 (2022).
[2] P. Makushko et al., A tunable room-temperature nonlinear Hall effect in elemental bismuth thin films. Nature Electronics 7, 207 (2024).
[3] D. Makarov et al., New Dimension in Magnetism and Superconductivity: 3D and Curvilinear Nanoarchitectures. Advanced Materials (Review) 34, 2101758 (2022).
[4] O. M. Volkov et al., Chirality coupling in topological magnetic textures with multiple magnetochiral parameters. Nature Communications 14, 1491 (2023).
[5] O. Volkov et al., Three-dimensional magnetic nanotextures with high-order vorticity in soft magnetic wireframes. Nature Communications 15, 2193 (2024).
[6] M. Ha et al., Reconfigurable Magnetic Origami Actuators with On-Board Sensing for Guided Assembly. Advanced Materials 33, 2008751 (2021).
[7] G. S. Canon Bermudez et al., Magnetosensitive e-skins for interactive devices. Advanced Functional Materials (Review) 31, 2007788 (2021).
[8] J. Ge et al., A bimodal soft electronic skin for tactile and touchless interaction in real time. Nature Communications 10, 4405 (2019).
[9] G. S. Canon Bermudez et al., Electronic-skin compasses for geomagnetic field driven artificial magnetoception and interactive electronics. Nature Electronics 1, 589 (2018).
[10] M. Ha et al., Printable and Stretchable Giant Magnetoresistive Sensors for Highly Compliant and Skin-Conformal Electronics. Advanced Materials 33, 2005521 (2021).
[11] E. S. Oliveros Mata et al., Dispenser printed bismuth-based magnetic field sensors with non-saturating large magnetoresistance for touchless interactive surfaces. Advanced Materials Technologies 7, 2200227 (2022).
[12] R. Xu et al., Self-healable printed magnetic field sensors using alternating magnetic fields. Nature Communications 13, 6587 (2022).
[13] X. Wang et al., Printed magnetoresistive sensors for recyclable magnetoelectronics. J. Mater. Chem. A 12, 24906 (2024).
[14] E. S. Oliveros Mata et al., Magnetically aware actuating composites: Sensing features as inspiration for the next step in advanced magnetic soft robotics. Phys. Rev. Appl. (Review) 20, 060501 (2023).
[15] L. Guo et al., Printable magnetoresistive sensors: A crucial step toward unconventional magnetoelectronics. Chinese Journal of Structural Chemistry (Review) 100428 (2024).

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

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  • Lecture (others)
    Seminar of the Department of Materials Science, 17.10.2024, Shanghai, China

Permalink: https://www.hzdr.de/publications/Publ-39740


Probing CLFV with the Mu2e Experiment at Fermilab

Müller, S.

Abstract

Presentation at "International Workshop on Baryon and Lepton Number Violation", Karlsruhe (Germany), Ovtober 8-11, 2024

Keywords: Mu2e; CLFV; FNAL

  • Open Access Logo Invited lecture (Conferences)
    International Workshop on Baryon and Lepton Number Violation, 08.-11.10.2024, Karlsruhe, Germany

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Permalink: https://www.hzdr.de/publications/Publ-39739


Predicting the electronic structure of matter at scale with machine learning

Cangi, A.

Abstract

In this presentation, I will discuss our recent advancements in utilizing machine learning to significantly enhance the efficiency of electronic structure calculations [1]. Specifically, I will focus on our efforts to accelerate Kohn-Sham density functional theory calculations by incorporating deep neural networks within the Materials Learning Algorithms framework [2,3]. Our results demonstrate substantial gains in calculation speed for metals across their melting point. Additionally, our implementation of automated machine learning has resulted in significant savings in computational resources when identifying optimal neural network architectures, laying the foundation for large-scale investigations [4]. Furthermore, I will present our most recent breakthrough, which enables neural-network-driven electronic structure calculations for systems containing over 100,000 atoms [5]. This achievement opens up new avenues for studying complex materials systems that were previously computationally intractable.

[1] L. Fiedler, K. Shah, M. Bussmann, A. Cangi, Phys. Rev. Materials, 6, 040301 (2022)
[2] A. Cangi, J. A. Ellis, L. Fiedler, D. Kotik, N. A. Modine, V. Oles, G. A. Popoola, S. Rajamanickam, S. Schmerler, J. A. Stephens, A. P. Thompson, Phys. Rev. B 104, 035120 (2021).
[3] J. Ellis, L. Fiedler, G. Popoola, N. Modine, J. Stephens, A. Thompson, A. Cangi, S. Rajamanickam, Phys. Rev. B, 104, 035120 (2021)
[4] L. Fiedler, N. Hoffmann, P. Mohammed, G. Popoola, T. Yovell, V. Oles, J. Austin Ellis, S. Rajamanickam, A. Cangi, Mach. Learn.: Sci. Technol., 3, 045008 (2022)
[5] L. Fiedler, N. Modine, S. Schmerler, D. Vogel, G. Popoola, A. Thompson, S. Rajamanickam, A. Cangi, npj. Comput. Mater., 9, 115 (2023)

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

  • Invited lecture (Conferences)
    Nano-Seminar, 17.10.2024, Dresden, Deutschland
    PURL: https://nano.tu-dresden.de/seminar/2024_10_17_attila-cangi

Permalink: https://www.hzdr.de/publications/Publ-39737


Intelligent Swarm: Concept, Design and Validation of Self-Organized UAVs Based on Leader–Followers Paradigm for Autonomous Mission Planning

Adoni, W. Y. H.; Lorenz, S.; Gloaguen, R.; Madriz Diaz, Y. C.; Singh, A.; Kühne, T. D.-S.

Abstract

Unmanned Aerial Vehicles (UAVs), commonly known as drones, are omnipresent and have grown in popularity due to their wide potential use in many civilian sectors. Equipped with sophisticated sensors and communication devices, drones can potentially form a multi-UAV system, also called an autonomous swarm, in which UAVs work together with little or no operator control. According to the complexity of the mission and coverage area, swarm operations require important considerations regarding the intelligence and self-organization of the UAVs. Factors including the types of drones, the communication protocol and architecture, task planning, consensus control, and many other swarm mobility considerations must be investigated. While several papers highlight the use cases for UAV swarms, there is a lack of research that addresses in depth the challenges posed by deploying an intelligent UAV swarm. Against this backdrop, we propose a computation framework of a self-organized swarm for autonomous and collaborative missions. The proposed approach is based on the Leader–Followers paradigm, which involves the distribution of ROS nodes among follower UAVs, while leaders perform supervision. Additionally, we have integrated background services that autonomously manage the complexities relating to task coordination, control policy, and failure management. In comparison with several research efforts, the proposed multi-UAV system is more autonomous and resilient since it can recover swiftly from system failure. It is also reliable and has been deployed on real UAVs for outdoor survey missions. This validates the applicability of the theoretical underpinnings of the proposed swarming concept. Experimental tests carried out as part of an area coverage mission with 6 quadcopters (2 leaders and 4 followers) reveal that the proposed swarming concept is very promising and inspiring for aerial vehicle technology. Compared with the conventional planning approach, the results are highly satisfactory, highlighting a significant gain in terms of flight time, and enabling missions to be achieved rapidly while optimizing energy consumption. This gives the advantage of exploring large areas without having to make frequent downtime to recharge and/or charge the batteries. This manuscript has the potential to be extremely useful for future research into the application of unmanned swarms for autonomous missions.

Keywords: UAV (unmanned aerial vehicle); RPAS; UAS; drones; multi-UAV systems; autonomous aerial swarm; unmanned aerial system; collaborative missions; ROS (robot operating system)

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Permalink: https://www.hzdr.de/publications/Publ-39736


FPGA-based measurements of the relative arrival time of a high-repetition rate, quasi-cw 4th generation light source

Ponomaryov, O.; Deinert, J.-C.; de Oliveira, T.; Ilyakov, I.; Prajapati, G. L.; Arshad, A.; Kuntzsch, M.; Kovalev, S.; Gensch, M.

Abstract

In this manuscript we demonstrate the successful implementation of reconfigurable field-programmable gate array (FPGA) technology into a pulse-resolved data acquisition (DAQ) system to achieve a femtosecond temporal resolution in ultrafast pump-probe experiments in real-time at large scale facilities. As a proof of a concept, electro-optic sampling (EOS) of terahertz waveforms radiated by a superradiant emitter of a quasi-cw accelerator operating at 50 kHz repetition rate and probed by external laser system is performed. Options for up-scaling the developed technique to a MHz range repetition rates are discussed.

Keywords: Accelerator-based light source; FPGA; THz radiation

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Permalink: https://www.hzdr.de/publications/Publ-39735


Data Publication: Boron isotopic and mineral chemical composition in greisen-related Li-Fe micas at the Sadisdorf Li-Sn-(W-Cu) prospect, Erzgebirge, Germany: Pathways and mechanisms for hydrothermal lithium enrichment

Leopardi, D.; Gerdes, A.; Albert, R.; Krause, J.; Gutzmer, J.; Lehmann, B.; Burisch, M.

Abstract

Data set composed of sample descriptions, major and trace element compositions of micas, in-situ B isotopic analyses of micas and whole-rock B isotopic compositions of major lithologies at the Sadisdorf prospect. 

Keywords: Li-Fe mica; Mineral geochemistry; B isotopes

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Permalink: https://www.hzdr.de/publications/Publ-39734


Pathway to industrial application of heterotrophic organisms in critical metals recycling from e-waste

Golzar-Ahmadi, M.; Bahaloo-Horeh, N.; Pourhossein, F.; Norouzi, F.; Schönberger, N.; Hintersatz, C.; Chakankar, M. V.; Holuszko, M.; Anna, H. K.

Abstract

The transition to renewable energies and electric vehicles has triggered an unprecedented demand for metals.
Sustainable development of these technologies relies on effectively managing the lifecycle of critical raw materials, including their responsible sourcing, efficient use, and recycling. Metal recycling from electronic waste
(e-waste) is of paramount importance owing to ore-exceeding amounts of critical elements and high toxicity of
heavy metals and organic pollutants in e-waste to the natural ecosystem and human body. Heterotrophic microbes secrete numerous metal-binding biomolecules such as organic acids, amino acids, cyanide, siderophores,
peptides, and biosurfactants which can be utilized for eco-friendly and profitable metal recycling. In this review
paper, we presented a critical review of heterotrophic organisms in biomining, and current barriers hampering
the industrial application of organic acid bioleaching and biocyanide leaching. We also discussed how these
challenges can be surmounted with simple methods (e.g., culture media optimization, separation of microbial
growth and metal extraction process) and state-of-the-art biological approaches (e.g., artificial microbial community, synthetic biology, metabolic engineering, advanced fermentation strategies, and biofilm engineering).
Lastly, we showcased emerging technologies (e.g., artificially synthesized peptides, siderophores, and biosurfactants) derived from heterotrophs with the potential for inexpensive, low-impact, selective and advanced
metal recovery from bioleaching solutions

Keywords: Critical metals; Recycling; Bioleaching; E-waste; Circular economy; Resource recovery

Permalink: https://www.hzdr.de/publications/Publ-39732


Trace element analysis and luminescence behavior of quartz in pegmatites of the Tørdal Region, Norway

Sittner, J.; Götze, J.; Müller, A.; Renno, A.; Ziegenrücker, R.; Pan, Y.

Abstract

This publication presents a study on the mineral chemistry and luminescence properties of quartz samples from pegmatites of the Tørdal region in Norway. A total of 12 samples were analyzed using Secondary Ion Mass Spectrometry (SIMS), Electron Paramagnetic Resonance Spectroscopy (EPR), and Cathodoluminescence (CL) to gain insights into their trace element concentration and distribution as well as their luminescence behavior. The samples are characterized by different Cl emissions at 450 nm, 500 nm 650 nm and an additional shoulder at 390 nm, which is only partially visible due to the absorption of the glass optics. Of these luminescence bands, the 500 nm band is the most dominant in most samples and it is characterized by an initial blue-green luminescence, which is not stable under electron irradiation. Moreover, it is characterized by a heterogeneous distribution within the samples. This luminescence can be mostly assigned to [AlO4/M+]0 defects, with charge compensation mostly achieved by Li+. Analyses by EPR spectroscopy prove the dominance of structurally bound Al, Li, and Ti ions in the investigated samples. Further analyses using SIMS mapping demonstrate that Na and K are mainly bound to micro fractures or inclusions, suggesting a limited role in the compensation of the luminescence centers. Additionally, the SIMS mappings show that some samples contain Al-rich clusters of 10 to 20 μm in diameter, whereas other trace elements are characterized by a homogeneous distribution. These clusters correspond to bright luminescence areas in size and shape and could potentially indicate H+ compensated [AlO4/M+]0 defects.

Keywords: Quartz; Trace elements; Cathodoluminescence; SIMS; EPR; Tørdal; Pegmatite

Permalink: https://www.hzdr.de/publications/Publ-39731


Immune modulatory microRNAs in tumors, their clinical relevance in diagnosis and therapy

Vaxevanis, C.; Bachmann, M.; Seliger, B.

Abstract

The importance of the immune system in regulating tumor growth by inducing immune cell-mediated cytotoxicity associated with patients’ outcomes has been highlighted in patients with cancer on treatment with different immunotherapeutics. However, tumors often escape immune surveillance, which is accomplished by different mechanisms. Recent studies demonstrated an essential role of small non-coding RNAs, such as microRNAs (miRNAs), in the post-transcriptional control of immune modulatory molecules. Multiple methods have been used to identify miRNAs targeting genes involved in escaping immune recognition including miRNAs targeting CTLA-4, PD-L1, HLA-G, components of the major histocompatibility class I antigen processing machinery (APM) as well as other immune response-relevant genes in tumors. Due to their function, these immune modulatory miRNAs can be used as (1) diagnostic and prognostic biomarkers allowing to discriminate between tumor stages and to predict the patients’ outcome as well as response and resistance to (immuno) therapies and as (2) therapeutic targets for the treatment of tumor patients. This review summarizes the role of miRNAs in tumor-mediated immune escape, discuss their potential as diagnostic, prognostic and predictive tools as well as their use as therapeutics including alternative application methods, such as chimeric antigen receptor T cells.

Permalink: https://www.hzdr.de/publications/Publ-39729


Bridging the gap in electronic structure calculations via machine learning

Cangi, A.

Abstract

A highly efficient reconstruction method has been developed for the direct computation of Hamiltonian matrices in the atomic orbital basis from density functional theory calculations originally performed in the plane wave basis. This enables machine learning calculations of electronic structures on a large scale, which are otherwise not feasible with standard methods, and thus fills a methodological gap in terms of accessible length scales.

Keywords: Electronic structure structure; Density functional theory; Machine learning; Neural networks; Deep learning; Basis sets

Permalink: https://www.hzdr.de/publications/Publ-39727


Characterizing Laser Transmission in the Relativistically Induced Transparency Regime for PW Laser-Driven Proton Acceleration

Umlandt, M. E. P.; Bernert, C.; Casati, G.; Cowan, T.; Dover, N. P.; Göthel, I.; Kiriyama, H.; Kluge, T.; Kon, A.; Kondo, K.; Kroll, F.; Liu, C.; Metzkes-Ng, J.; Najmudin, Z.; Nishiuchi, M.; Paschke-Brühl, F.-L.; Pausch, R.; Püschel, T.; Rana, V.; Rehwald, M.; Sakaki, H.; Vescovi Pinochet, M. A.; Wang, P.; Zeil, K.; Ziegler, T.; Schramm, U.

Abstract

Ion acceleration through compact laser-plasma sources holds great potential for diverse applications, from medical treatments to fusion experiments. Achieving the required beam quality parameters demands a deep understanding and precise control of the laser-plasma interaction process. Our ongoing collaborative research at DRACO PW (HZDR) and J-KAREN-P (KPSI) laser systems focuses on exploring the promising regime of Relativistically Induced Transparency (RIT).
In previous studies [1], we observed high-performance proton beams (>60 MeV) in an expanded foil case, showcasing an optimum at the onset of target transparency. Subsequent experiments revealed even higher proton energies beyond 100 MeV [2], emphasizing the important role of the transparency onset time in optimizing beam parameters and enhancing process robustness. We employ a combination of particle and laser diagnostics to explore the correlation between transparency onset and acceleration performance.
This contribution highlights our recent investigations into spectral and spatial components of transmission and emission arising from the laser-plasma interaction. Building upon established methodologies [3,4], our approach involves spectral interferometry, using the unperturbed laser beam as a reference, and correlating findings with proton acceleration performance. Our results suggest a promising avenue for a focused analysis of spectral and spatial distribution, offering additional insights into the complexities of the laser-plasma interaction process. By emphasizing these aspects, we aim to deepen our understanding of factors influencing ion acceleration, contributing to the optimization of beam quality parameters.
[1] Dover, N.P. et al.: Light Sci. Appl. 12, 71 (2023).
[2] Ziegler, T. et al.: Nat. Phys. accepted (2024).
[3] Bagnoud, V. et al.: Phys. Rev. Lett. 118, 255003 (2017).
[4] Williamson, S.D.R. et al.: Phys. Rev. Appl. 14, 034018 (2020).

Keywords: laser plasma; laser proton acceleration; high power laser; laser ion acceleration; laser solid interaction

Involved research facilities

  • Draco
  • Lecture (Conference)
    EPS Conference on Plasma Physics 2024, 08.-12.07.2024, Salamanca, España
  • Lecture (Conference)
    Advanced Accelerator Concepts Workshop 2024, 21.-26.07.2024, Naperville, United States of America

Permalink: https://www.hzdr.de/publications/Publ-39725


Investigating Recurrent Matere Bonds in Pertechnetate Compounds

Grödler, D.; Burguera, S.; Frontera, A.; Strub, E.

Abstract

In this manuscript we evaluate the X-ray structure of five new pertechnetate derivatives of general formula [M(H₂O)₄(TcO₄)₂], M=Mg, Co, Ni, Cu, Zn (compounds 1–5) and one perrhenate compound Zn(H₂O)₄(ReO₄)₂ (6). In these complexes the metal center exhibits an octahedral coordination with the pertechnetate units as axial ligands. All compounds exhibit the formation of directional Tc⋅⋅⋅O Matere bonds (MaBs) that propagate the [M(H₂O)₄(TcO₄)₂], into 1D supramolecular polymers in the solid state. Such 1D polymers are linked, generating 2D layers, by combining additional MaBs and hydrogen bonds (HBs). Such concurrent motifs have been analyzed theoretically, suggesting the noncovalent σ-hole nature of the MaBs. The interaction energies range from weak (~ −2 kcal/mol) for the MaBs to strong (~ −30 kcal/mol) for the MaB+HB assemblies, where HB dominates. In case of M=Zn, the corresponding perrhenate Zn(H₂O)₄(ReO₄)₂ complex, has been also synthesized for comparison purposes, resulting in the formation of an isostructural X-ray structure, corroborating the structure-directing role of Matere bonds.

Keywords: Pertechnetate; Perrhenate; matere bonds; supramolecular chemistry

Permalink: https://www.hzdr.de/publications/Publ-39722


Trace-scale extraction of carrier-free tungsten radioisotope as a homolog of Sg using ionic liquid from acid solutions: Kinetic study

Attallah, M. F.; Elchine, D.; Grödler, D.; Margreiter, R.; Maslo, M.; Michel, M.; Petter Omtvedt, J.; Strub, E.; von Döllen, S.

Abstract

This study aimed to find a rapid extraction system for the preparation of a Seaborgium (Sg) aqueous chemistry experiment in the future. A new approach for extraction of ¹⁸¹W tracer as a lighter homolog of (Sg) by ionic liquids is explored. A natural tantalum target was activated by a beam of 9 MeV proton at Cologne University to produce carrier-free ¹⁸¹W. The preliminary batch extraction experiments of the carrier-free ¹⁸¹W from HCl and H₂SO₄ solutions have been evaluated. Different batch extraction parameters such as feed acidity, diluent type, ionic strength (KCl feed) and reducing agent as a function of time were explored. The obtained results demonstrated that the highest distribution of carrier-free ¹⁸¹W from 0.001 M acidic solutions using the used ionic liquid is observed. A significant rapid kinetic for the extraction of trace-scale using the used ionic liquid is achieved within 5 sec. The preliminary results are necessary to design the upcoming aqueous experiments of Sg. The next goal will be on-line experiments with the centrifuge system SISAK to develop the aqueous chemistry extraction of Sg using the most promising and adequate experimental setup.

Keywords: Chemistry of superheavy elements; Seaborgium; Separation of radioisotopes; Ionic liquid

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Permalink: https://www.hzdr.de/publications/Publ-39721


Pertechnetates – A Structural Study Across the Periodic Table

Strub, E.; Grödler, D.; Zaratti, D.; Yong, C.; Dünnebier, L.; Bazhenova, S.; Roca Jungfer, M.; Breugst, M.; Zegke, M.

Abstract

The number of crystal structures of pertechnetates derived from aqueous solutions has been expanded from seven to over 30. We report the conversion of NH₄TcO₄ to aqueous HTcO₄ via acidic cation exchange. This is followed by the synthesis and structural elucidation of pertechnetate salts of alkaline earth (AE), transition metal I and lanthanoids (Ln) elements. Various degrees of hydration and coordination are discussed. Where possible, a comparison with the perrhenate homologues is made. The described syntheses and materials may be used as novel starting materials for extended technetium research.

Keywords: Technetium; Pertechnetates; Pertechnetic Acid; Crystallography

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Permalink: https://www.hzdr.de/publications/Publ-39719


Electronic Lieb Lattice Signatures Embedded in 2D Polymers with Square Pore

Zhang, Y.

Abstract

Exotic band features, such as Dirac cones and flat bands, arise directly from the lattice symmetry of materials. The Lieb lattice is one of the most intriguing topologies, because it possesses both Dirac cones and flat bands which intersect at the Fermi level. However, the synthesis of Lieb lattice materials remains a challenging task. Here, we explore two-dimensional polymers (2DPs) derived from zinc-phthalocyanine (ZnPc) building blocks with a square lattice (sql) as potential electronic Lieb lattice materials. By systematically varying the linker length (ZnPc-xP), we found that some ZnPc-xP exhibit a characteristic Lieb lattice band structure. Interestingly though, fes bands are also observed in ZnPc-xP. The coexistence of fes and Lieb in sql 2DPs challenges the conventional perception of the structure–electronic structure relationship. In addition, we show that manipulation of the Fermi level, achieved by electron removal or atom substitution, effectively preserves the unique characteristics of Lieb bands. The Lieb Dirac bands of ZnPc-4P shows a non-zero Chern number. Our discoveries provide a fresh perspective on 2DPs and redefine the search for Lieb lattice materials into a well-defined chemical synthesis task.

  • Poster
    Saxony Meets Lower Silesia: Science Across Borders, 17.06.2024, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-39716


Prospects for free-electron lasers powered by plasma-wakefield-accelerated beams

Galletti, M.; Assmann, R.; Couprie, M.-E.; Ferrario, M.; Giannessi, L.; Irman, A.; Pompili, R.; Wang, W.

Abstract

Plasma-wakefield-based acceleration technology has the potential to revolutionize the field of particle accelerators. By providing acceleration gradients orders of magnitude larger than conventional radiofrequency particle accelerators, this technology allows accelerators to be reduced to the centimetre length scale. It also provides a new compact approach for driving free-electron lasers, a valuable source of high-brilliance ultrashort coherent radiation within the infrared to X-ray spectral range for the study of subatomic matter, ultrafast dynamics of complex systems and X-ray nonlinear optics, among other applications. Several laboratories around the world are working on the realization of these new light sources, exploring different configurations for the plasma wakefield driver beam, plasma stage design and operational regime. This Review describes the operating principles of plasma accelerators, an overview of recent experimental milestones for plasma-driven free-electron lasers in self-amplified spontaneous emission and seeded configurations, and highlights the remaining major challenges in the field.

Keywords: plasma driven free electron laser

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  • Draco

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Permalink: https://www.hzdr.de/publications/Publ-39713


Data publication: Application of Phage Surface Display for the Identification of Eu3+-binding Peptides

Techert, G.; Drobot, B.; Braun, R.; Bloß, C.; Schönberger, N.; Matys, S.; Pollmann, K.; Lederer, F.

Abstract

1. Sequenzierdaten als Excel-File zu Europiumion-bindenden Peptiden

2. TRLFS-Rohdaten zu Bindungsstudien von potenziell Europiumion-bindenden Peptiden mit Europiumionen

3. TRLFS-Diagramme zu Bindungsstudien von potenziell Europiumion-bindenden Peptiden mit Europiumionen

Keywords: europium; REE recovery; phage surface display; peptides; next generation sequencing

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Permalink: https://www.hzdr.de/publications/Publ-39712


Wettability-dependent dissolution dynamics of oxygen bubbles on Ti64 substrates

Dai, H.; Yang, X.; Schwarzenberger, K.; Heinrich, J.; Eckert, K.

Abstract

In this study, the dissolution of a single oxygen bubble on a solid surface, here Titanium alloy Ti64, in ultrapure water with different oxygen undersaturation levels is investigated. For that purpose, a combination of shadowgraph technique and planar laser-induced fluorescence is used to measure simultaneously the changes in bubble geometry and in the dissolved oxygen concentration around the bubble. Two different wettabilities of the Ti64 surface are adjusted by using plasma-enhanced chemical vapor deposition. The dissolution process on the solid surface involves two distinct phases, namely bouncing of the oxygen bubble at the Ti64 surface and the subsequent dissolution of the bubble, primarily by diffusion. By investigating the features of oxygen bubbles bouncing, it was found that the boundary layer of dissolved oxygen surrounding the bubble surface is redistributed by the vortices emerging during bouncing. This establishes the initial conditions for the subsequent second dissolution phase of the oxygen bubbles on the Ti64 surfaces. In this phase, the mass transfer of O2 proceeds non-homogeneously across the bubble surface, leading to an oxygen accumulation close to the Ti64 surface. We further show that the main factor influencing the differences in the dynamics of O2 bubble dissolution is the variation in the surface area of the bubbles available for mass transfer, which is determined by the substrate wettability. As a result, dissolution proceeds faster at the hydrophilic Ti64 surface due to the smaller contact angle, which provokes a larger surface area.

Keywords: Uncoated and coated Ti64 substrate; PLIF; Shadowgraph measurement; Concentration gradient; Bubble shape

Permalink: https://www.hzdr.de/publications/Publ-39708


An SRF gun driving the ELBE IR-FEL with up to 1mA in CW

Arnold, A.

Abstract

At the electron accelerator for beams with high brilliance and low emittance (ELBE), the second version of a superconducting radio-frequency (SRF) photoinjector was brought into operation in 2014. After a period of commissioning, a gradual transfer to routine operation took place in 2017, so that now more than 1800h of user beam are generated every year. In addition to this routine operation with a few tens of microamperes, another important goal, the generation of an average current of 1 mA, which is high for electron linear accelerators, could now be demonstrated with our SRF gun. At the same time, this beam was already accelerated to almost 30 MeV by the ELBE LINAC and irradiated in one of the IR-FELs. This is particularly important with regard to the successor of the ELBE accelerator called DALI, which will be also fed by an SRF gun with a high average current. The contribution presents the most important steps for achieving the full beam current and summarizes related measurement results and findings. No fundamental difficulties were identified.

Keywords: SRF gun; photocathode; superconducting electron source; injector; ELBE; high current; mA; IR FEL

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  • Open Access Logo Invited lecture (Conferences)
    10th Matter and Technologies annual meeting, 17.-20.09.2024, Berlin, Deutschland
    PURL: https://indico.desy.de/event/45079/contributions/174026/
  • Open Access Logo Invited lecture (Conferences)
    69th ICFA Advanced Beam Dynamics Workshop on Energy Recovery Linacs (ERL2024), 24.-27.09.2024, Tsukuba, Japan
  • Open Access Logo Lecture (others)
    Annual Gun Cluster Meeting 2024, 20.06.2024, Berlin, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-39705


Differential pressure measurements in bubble columns of different diameter, operated with various physical systems

Marchini, S.; Kipping, R.; Tim Dalu, K.

Abstract

The dataset was acquired over several measurement campaigns and contains differential pressure measurements in bubble columns of several diameters (100, 150, 330 mm) operated with gas in continuum (dry air) and liquid in batch. The fact that no humidification was provided was shown to have negligible influence. Liquid temperature was between 20-22°C. Pressure was atmospheric (column open to the environment).

For additional details, refer to the READ_ME and DETAILS_Setup files included in the dataset.

Keywords: bubble column; gas holdup; differential pressure; flow map

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Permalink: https://www.hzdr.de/publications/Publ-39704


Graphene bilayer as a template for manufacturing novel encapsulated 2D materials

Krasheninnikov, A.; Lin, Y.-C.; Suenaga, K.

Abstract

Bilayer graphene (BLG) has recently been used as a tool to stabilize the encapsulated single sheets of various layered materials and tune their properties. It was also discovered that the protecting action of graphene sheets makes it possible to synthesize completely new two-dimensional materials (2DMs) inside BLG by intercalating
various atoms and molecules. In comparison to the bulk graphite, BLG allows for easier intercalation and much larger increase in the inter-layer separation of the sheets. Moreover, it enables studying the atomic structure of the intercalated 2DM using high-resolution transmission electron microscopy. In this review, we summarize the recent
progress in this area, with a special focus on new materials created inside BLG. We compare the experimental findings with the theoretical predictions, pay special attention to the discrepancies and outline the challenges in the field. Finally, we discuss unique opportunities offered by the intercalation into 2DMs beyond graphene and their
heterostructures.

Keywords: 2D materials; intercalation; First-principles calculations

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Permalink: https://www.hzdr.de/publications/Publ-39703


Data publication: Effects of mosaic crystal instrument functions on x-ray Thomson scattering diagnostics

Gawne, T. D.; Bellenbaum, H.; Fletcher, L. B.; Appel, K.; Bähtz, C.; Bouffetier, V.; Brambrink, E.; Brown, D.; Cangi, A.; Descamps, A.; Goede, S.; Hartley, N. J.; Herbert, M.-L.; Hesselbach, P.; Höppner, H.; Humphries, O. S.; Konôpková, Z.; Laso García, A.; Lindqvist, B.; Lütgert, J.; MacDonald, M. J.; Makita, M.; Martin, W.; Mishchenko, M.; Moldabekov, Z.; Nakatsutsumi, M.; Naedler, J.-P.; Neumayer, P.; Pelka, A.; Qu, C.; Randolph, L.; Rips, J.; Toncian, T.; Vorberger, J.; Wollenweber, L.; Zastrau, U.; Kraus, D.; Preston, T. R.; Dornheim, T.

Abstract

Datasets of various model source and instrument functions, simulations of dynamic structure factors, and experimental data from the publications, as well as figures.

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  • HIBEF

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Permalink: https://www.hzdr.de/publications/Publ-39702


Investigation of the interactions of microorganisms with uranium in anthropogenic contaminated waters as basis for the development of a bioremediation technology. (Investigación de las interacciones de los microorganismos con el uranio en aguas contaminadas de origen antropogénico como base para el desarrollo de una tecnología de biorremediación)

Newman Portela, A.

Abstract

Uranium (U) mining has left a legacy of environmental contamination in the Federal States of Saxony and Thuringia (Germany). High concentrations of U and other heavy metals pose a potential threat to both the environment and human health, through contamination of soil and water. Additionally, it is well documented that other human activities, such as agronomic practices and military conflicts, have contributed to increasing the concentration of these contaminants. However, U has become one of the world's most important elements in the last 60 years due to its potential use in nuclear energy production. Therefore, it is essential to develop environmental rehabilitation programs in affected areas, along with adopting waste management practices that promote sustainability, including the possibility of recovering U from waste for reuse within the concept of circular economy.

Traditionally, physicochemical based conventional technologies have been used to remediate environments contaminated with U. However, these approaches tend to be costly, complex to apply, and ineffective for low concentrations of U. Hence, a promising alternative, less expensive, easy to implement, and effective for low U concentrations is bioremediation, based on the interaction mechanisms of biological systems with U. Based on extensive available literature, the main suggested strategies for U bioremediation include two approaches: biomineralization of U(VI) phosphates under oxic conditions and enzymatic reduction under anoxic conditions from soluble, highly mobile, and bioavailable U(VI) to insoluble, less mobile, and thus less bioavailable U(IV).

The aim of this PhD thesis was to characterize, through a multidisciplinary approach, two former German mine waters contaminated with U, Schlema-Alberoda and Pöhla (Wismut GmbH), in order to design a future U bioremediation strategy based on biostimulation of the native U-reducing microbial community.

The bioremediation of contaminated waters with low U concentrations shows a significant challenge, which can be addressed by stimulating U-reducing bacterial activity, as described in this PhD thesis. Moreover, this study not only provides new insights on the reduction of U(VI) to U(IV) but also emphasizes that the resulting product, U(V), is more stable than uraninite, thus increasing the potential of this strategy, considering the risk of U reoxidation.

Keywords: Uranium; Mine Water; Bioremediation

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  • Open Access Logo Doctoral thesis
    University of Granada, Granada, Spain, 2024
    Mentor: Raff, J.; Merroun, M. L.; Krawczyk-Bärsch, E
    372 Seiten

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Permalink: https://www.hzdr.de/publications/Publ-39701


Effects of mosaic crystal instrument functions on x-ray Thomson scattering diagnostics

Gawne, T. D.; Bellenbaum, H.; Fletcher, L. B.; Appel, K.; Bähtz, C.; Bouffetier, V.; Brambrink, E.; Brown, D.; Cangi, A.; Descamps, A.; Goede, S.; Hartley, N. J.; Herbert, M.-L.; Hesselbach, P.; Höppner, H.; Humphries, O. S.; Konôpková, Z.; Laso García, A.; Lindqvist, B.; Lütgert, J.; MacDonald, M. J.; Makita, M.; Martin, W.; Mishchenko, M.; Moldabekov, Z.; Nakatsutsumi, M.; Naedler, J.-P.; Neumayer, P.; Pelka, A.; Qu, C.; Randolph, L.; Rips, J.; Toncian, T.; Vorberger, J.; Wollenweber, L.; Zastrau, U.; Kraus, D.; Preston, T. R.; Dornheim, T.

Abstract

Mosaic crystals, with their high integrated reflectivities, are widely employed in spectrometers used to diagnose high energy density systems. X-ray Thomson scattering (XRTS) has emerged as a powerful diagnostic tool of these systems, providing in principle direct access to important properties such as the temperature via detailed balance. However, the measured XRTS spectrum is broadened by the spectrometer instrument function (IF), and without careful consideration of the IF one risks misdiagnosing system conditions. Here, we consider in detail the IF of 40 and 100 μm mosaic Highly Annealed Pyrolytic Graphite crystals, and how the broadening varies across the spectrometer in an energy range of 6.7–8.6 keV. Notably, we find a strong asymmetry in the shape of the IF toward higher energies. As an example, we consider the effect of the asymmetry in the IF on the temperature inferred via XRTS for simulated 80 eV CH plasmas and find that the temperature can be overestimated if an approximate symmetric IF is used. We, therefore, expect a detailed consideration of the full IF will have an important impact on system properties inferred via XRTS in both forward modeling and model-free approaches.

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  • HIBEF

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Permalink: https://www.hzdr.de/publications/Publ-39699


Investigation of the interactions of microorganisms with uranium in anthropogenic contaminated waters as basis for the development of a bioremediation technology

Newman Portela, A.; Kvashnina, K.; Bazarkina, E.; Roßberg, A.; Bok, F.; Kassahun, A.; Raff, J.; Merroun, M. L.; Krawczyk-Bärsch, E.

Abstract

At the technical colloquium on September 5th, Antonio Newman will present the findings of his PhD thesis. This project was developed in collaboration between the University of Granada (Spain) and the Helmholtz-Zentrum Dresden-Rossendorf (Germany), in collaboration with Wismut GmbH.
The project first geochemically characterized the mine water from Schlema-Alberoda and Pöhla using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and High Pressure Ion Chromatography (HPIC). Simultaneously, it analysed the microbial community through sequencing of bacterial 16S rRNA and fungal ITS genes. Additionally, this work explored key metabolic pathways involved in the biogeochemical cycles of sulphur, nitrogen, and carbon using metatranscriptomic analysis to understand the differences in U concentrations between the two mine waters. The study also involved isolating, identifying, and biochemically characterizing fungi from these waters, searching for strains with U immobilization potential. Finally, a complementary bioremediation strategy was designed and optimized to reduce U in the Schlema-Alberoda mine water, using the native bacterial community and glycerol as an electron donor, while characterizing the reduced U products with spectroscopic (e.g., High-Energy-Resolution Fluorescence Detected X-Ray Absorption Near Edge Structure (HERFD-XANES) and (Extended X-Ray Absorption Fine Structure (EXAFS)) and microscopic techniques (e.g., HRTEM).
The most notable findings of this PhD thesis include the effectiveness of using glycerol as an electron donor to stimulate the native microbial community involved in reducing soluble U in the Schlema-Alberoda mine water as a bioremediation strategy. Additionally, the study reports not only the reduction of U(IV) but also surprisingly high proportions of biogenic stable U(V), which had not been previously documented in the literature.

Keywords: Uranium; Mine Water; Bioremediation

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  • Lecture (others)
    Wismut GmbH - Technisches Kolloquium, 05.09.2024, Chemnitz, Germany

Permalink: https://www.hzdr.de/publications/Publ-39698


Heat flow data from the fungus Schizophyllum commune: example file for the software tool METABOLATOR

Fahmy, K.; Günther, A.; Bertheau, R.; Pape, D.

Abstract

The Excel file contains heat flow data from Schizophyllum commune cultures grown at 30 °C at different glucose concentrations. Measurements were carried out with a TAMIII instrument (TA-Waters) using 4 mL ampoules filled with 2 mL of growth medium.The heat flow curves show an oxidative phase followed by a fermentative phase at high glucose concentration. The two corresponding peaks can be evaluated indepndently by chosing the appropriate heat range. (The publication DOI:10.14278/rodare.3152 contains these data with the according analysis results). The Excel file serves also as a template for users to paste in their raw data. The format must not be changed for successful upload in METABOLATOR (DOI: 10.14278/rodare.3150). METABOLATOR is still being developed. Comments, reports on errors, suggestions can be sent to metabolator@hzdr.de

Keywords: metabolator; microcalorimetry; microbes; bacteria; growth; kinetics

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Permalink: https://www.hzdr.de/publications/Publ-39694


Data publication: Gallium recovery from red mud: Integration of solvent extraction and siderophore assisted technologies

Dhiman, S.; Fuloria, N.; Ghosh, A.; Chaudhary, S.; Ziauddin Ahammad, S.; Tsushima, S.; Kelly, N.; Jain, R.

Abstract

The raw data that was used in the study.

Keywords: Leaching; GaLIophore; Cyphos IL 104; Desferrioxamine B; Density functional theory

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Permalink: https://www.hzdr.de/publications/Publ-39691


Gallium recovery from red mud: Integration of solvent extraction and siderophore assisted technologies

Dhiman, S.; Fuloria, N.; Ghosh, A.; Chaudhary, S.; Ziauddin Ahammad, S.; Tsushima, S.; Kelly, N.; Jain, R.

Abstract

Gallium (Ga) recovery from the red mud, though important has never been successful due to several technical and economic reasons such as contaminant interference and the high cost of membranes due to their faster saturation resulting in the clogging of membranes with contaminants. This study demonstrated the recovery of Ga by a combination of HCl-based leaching, Fe/Al/Ti separation, and recovery of Ga using Cyphos IL 104-based solvent extraction and complexation of Ga with desferrioxamine B as a proof-of-principle of the GaLIophore technology. The main leaching parameters such as concentrations of acids, time and temperature of the reaction, and solid-to-liquid ratio have been systematically investigated. The optimal leaching conditions were determined as 4 mol/L HCl, 2 h time, 80 °C temperature, and solid-to-liquid ratio 1:20 (g/mL) attaining a more than 90% leaching of Ga. Subsequently, more than 99% Ga was extracted from the leachate using 0.05 mol/L Cyphos IL 104 at A:O ratio 1 and stripped by 0.01 mol/L H2SO4 at O:A ratio 1 from the organic phase. Desferrioxamine B (DFOB) demonstrated selectivity by complexing with more than 90% Ga in a stripped solution. The interaction between extractable species of Ga and Cyphos IL 104 was studied by Density Functional Theory (DFT) calculations and infrared spectroscopy. The whole process demonstrated the recovery of Ga by more than 80% present in the red mud. Further, the preliminary economic analysis suggests that the process can be profitable when Fe, Al, Sc, and Ga are recovered at a minimum rate of 50, 50, 75, and 75%.

Keywords: Leaching; GaLIophore; Cyphos IL 104; Desferrioxamine B; Density functional theory

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Permalink: https://www.hzdr.de/publications/Publ-39690


Einstein–Stokes relation for small bubbles at the nanoscale

Zhou, Y.; Huang, M.; Tian, F.; Shi, X.; Zhang, X.

Abstract

As the physicochemical properties of ultrafine bubble systems are governed by their size, it is crucial to determine the size and distribution of such bubble systems. At present, the size or size distribution of nanometer-sized bubbles in suspension is often measured by either dynamic light scattering or the nanoparticle tracking analysis. Both techniques determine the bubble size via the Einstein–Stokes equation based on the theory of the Brownian motion. However, it is not yet clear to which extent the Einstein–Stokes equation is applicable for such ultrafine bubbles. In this work, using atomic molecular dynamics simulation, we evaluate the applicability of the Einstein–Stokes equation for gas nanobubbles with a diameter less than 10 nm, and for a comparative analysis, both vacuum nanobubbles and copper nanoparticles are also considered. The simulation results demonstrate that the diffusion coefficient for rigid nanoparticles in water is found to be highly consistent with the Einstein–Stokes equation, with slight deviation only found for nanoparticle with a radius less than 1 nm. For nanobubbles, including both methane and vacuum nanobubbles, however, large deviation from the Einstein–Stokes equation is found for the bubble radius larger than 3 nm. The deviation is attributed to the deformability of large nanobubbles that leads to a cushioning effect for collision-induced bubble diffusion.

Permalink: https://www.hzdr.de/publications/Publ-39688


SU(2) gauge theory with one and two adjoint fermions towards the continuum limit

Athenodorou, A.; Bennett, E.; Bergner, G.; Butti, P.; Lenz, J.; Lucini, B.

Abstract

We provide an extended lattice study of the SU(2) gauge theory coupled to one Dirac fermion flavour (Nf=1Nf​=1) transforming in the adjoint representation as the continuum limit is approached. This investigation is supplemented by numerical results obtained for the SU(2) gauge theory with two Dirac fermion flavours (Nf=2Nf​=2) transforming in the adjoint representation, for which we perform numerical investigations at a single lattice spacing value, which is analysed together with earlier calculations. The purpose of our study is to advance the characterisation of the infrared properties of both theories, which previous investigations have concluded to be in the conformal window. For both, we determine the mass spectrum and the anomalous dimension of the fermion condensate using finite-size hyperscaling of the spectrum, mode number analysis of the Dirac operator (for which we improve on our previous proposal) and the ratio of masses of the lightest spin-2 particle over the lightest scalar. All methods provide a consistent picture, with the anomalous dimension of the condensate γ∗γ∗​ decreasing significantly as one approaches the continuum limit for the Nf=1Nf​=1 theory towards a value consistent with γ∗=0.174(6)γ∗​=0.174(6), while for Nf=2Nf​=2 the anomalous dimension decreases more slowly with ββ. A chiral perturbation theory analysis show that the infrared behaviour of both theories is incompatible with the breaking of chiral symmetry.

Keywords: High Energy Physics

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Permalink: https://www.hzdr.de/publications/Publ-39686


DRACO-HELIPORT integration for metadata enhanced data-acquisition

Lokamani, M.; Pape, D.; Knodel, O.; Bock, S.; Schramm, U.; Kelling, J.; Juckeland, G.

Abstract

The Dresden laser acceleration source (DRACO) is a state-of-the-art high-power ultra-short pulse laser system[1,2],
that uses an Amplitude Technologies Pulsar architecture to form main and diagnostics beams at different focal lengths and target density conditions.
The setup can deliver from 6J to 45J of pulse energy at a typical pulse duration of 30fs and a typical frequency of 1Hz.
During the diagnostic phase, the beam characteristics are recorded in the form of images and several instrument parameters,
that shape the beam to desired characteristics.

In this talk, we present our approach of implementing FAIR principles to DRACO
operations and monitoring using our in-house guidance system HELIPORT[3],
with the goal of making them reusable irrespective of the downstream experiment.
We employ FAIR workflows[4] to post-process data collected by DRACO's built-in data
acquisition system and enrich it with metadata for subsequent utilization in
machine-learning and optimization algorithms for accurate control of the beam characteristics.
The intergration of DRACO and HELIPORT demonstrates the first step towards establishing
a digital twin for the laser source facility at HZDR.

[1] First results with the novel Petawatt laser acceleration facility in Dresden, U. Schramm et al, J. Phys. Conf. Ser. 874 012028 (2017)
[2] High dynamic, high resolution and wide range single shot temporal pulse contrast measurement, T. Oksenhendler et. al., Opt. Express 25, 12588-12600 (2017)
[3] HELIPORT: A Portable Platform for FAIR {Workflow | Metadata | Scientific Project Lifecycle} Management and Everything, O. Knodel et. al., P-RECS (2021)
[4] FAIR Computational workflows, C. Goble et. al., Data Intelligence (2020) 2, 108 (2020)

Keywords: Research Software Engineering; DRACO; HELIPPOT; Data mangement

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  • Open Access Logo Lecture (Conference)
    Nobugs 2024, 23.-27.09.2024, Grenoble, France

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Permalink: https://www.hzdr.de/publications/Publ-39685


Nitrosyl and Thionitrosyl Complexes of Technetium and Rhenium and Their Reactions with Hydrotris(pyrazolyl)borates

Sawallisch, T. E.; Abdulkader, A.; Nowak, D.; Hagenbach, A.; Abram, U.

Abstract

The very limited number of structurally known thionitrosyl complexes of technetium was increased by the synthesis of [Tcᴵᴵ(NS)Cl₃(PPh₃)₂] (3) and [Tcᴵᴵ(NS)Cl₃(PPh₃)(OPPh₃)] (4) and their reaction products with hydrotris(pyrazolyl)borates, {HB(pzᴿ)₃}⁻. Similar reactions were conducted with [Tcᴵ(NO)Cl₂(PPh₃)₂(CH₃CN)] and related rhenium thionitrosyls. Remarkably, most such reactions result in a rapid cleavage of the boron–nitrogen bonds of the ligands and the formation of pyrazole complexes of the two group 7 metals. Only one compound with an intact {HB(pzᴿ)₃}⁻ ligand could be isolated: the technetium(I) complex [Tcᴵ(NO)Cl(PPh₃){HB(pz)₃}] (2). Other products show the coordination of one or four neutral pyrazole ligand(s) in the coordination spheres of technetium generated by thermal decomposition of the pyrazolylborates [Tcᴵ(NO)Cl₂(PPh₃)₂(pzᴴ)] (1) and [Tcᴵ(NS)Cl(pzᴴᴹᵉ²)₄]⁺ (5). Reactions with the corresponding thionitrosylrhenium complex [Reᴵᴵ(NS)Cl₃(PPh₃)₂] require higher temperatures and only compounds with one pyrazole ligand, [Reᴵ(NS)Cl₂(PPh₃)(pzᴴᴿ)] (6a–6c), were isolated. The products were studied spectroscopically and by X-ray diffraction.

Keywords: technetium; rhenium; nitrosyl complexes; thionitrosyl complexes; pyrazolylborates

Permalink: https://www.hzdr.de/publications/Publ-39684


A Scintillator Detector for Spatiospectral Characterization of Proton Beams at High Repetition Rate

Huault, M.; Ehret, M.; de Luis, D.; Antonio Pérez-Hernández, J.; Imanol Apiñaniz, J.; Luis Henares, J.; Malko, S.; Touati, M.; Gordillo, N.; Gutiérrez Neira, C.; Metzkes-Ng, J.; Reimold, M.; Schramm, U.; Zeil, K.; Roso, L.; Gatti, G.; Volpe, L.

Abstract

We present the experimental results of a 2-D scintillator-based detector developed at the Centro de Laseres Pulsados (CLPU) aiming at the spatiospectral characterization of proton beams driven by ultrarelativistic laser pulses at a high repetition rate (HRR). We report its implementation in laser-driven proton acceleration at the VEGA (CLPU) laser facility to demonstrate its operation. The analysis of the obtained results shows the relevance of the presented diagnostic for HRR acquisition of laser-driven proton sources promoting it as an essential tool for large parametric studies in the emerging field of laser-driven accelerators. A validation of the spectral and divergence reconstruction method is also presented together with the scintillator calibration performed at the conventional accelerator Centro de Micro-Análisis de Materiales (CMAM) in Madrid, Spain.

Keywords: Detectors; Scintillators; Protons; Laser beams; Imaging; Spatial resolution; Ions; High repetition rate (HRR); ion diagnostic; laser particle acceleration; online detector; scintillator

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  • Draco

Permalink: https://www.hzdr.de/publications/Publ-39683


UniCAR T-Cell Potency—A Matter of Affinity between Adaptor Molecules and Adaptor CAR T-Cells?

Boutier, H.; Rodrigues Loureiro, L. R.; Hoffmann, L.; Arndt, C.; Feldmann, A.; Bartsch, T.; Bachmann, M.

Abstract

Manuscript published in IJMS + figures

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Permalink: https://www.hzdr.de/publications/Publ-39682


Substrate deformability and applied normal force are coupled to change nanoscale friction

Yu, Z.; Huang, M.; Zhang, X.

Abstract

Amonton's law of friction states that the friction force is proportional to the normal force in magnitude, and the slope gives a constant friction coefficient. In this work, with molecular dynamics simulation, we study how the kinetic friction at the nanoscale deviates qualitatively from the relation. Our simulation demonstrates that the friction behavior between a nanoscale AFM tip and an elastic graphene surface is regulated by the coupling of the applied normal force and the substrate deformability. First, it is found that the normal load-induced substrate deformation could lower friction at low load while increasing it at high load. In addition, when the applied force exceeds a certain threshold another abrupt change in friction behavior is observed, i.e., the stick–slip friction changes to the paired stick–slip friction. The unexpected change in friction behavior is then ascribed to the change of the microscopic contact states between the two surfaces: the increase in normal force and the substrate deformability together lead to a change in the energy landscape experienced by the tip. Finally, the Prandtl–Tomlinson model also validates that the change in friction behavior can be interpreted in terms of the energy landscape.

Permalink: https://www.hzdr.de/publications/Publ-39680


Transition from ferromagnetic to noncollinear to paramagnetic state with increasing Ru concentration in FeRu films

Lisik, J.; Rojas, M.; Myrtle, S.; Ryan, D. H.; Hübner, R.; Omelchenko, P.; Abert, C.; Ducevic, A.; Suess, D.; Soldatov, I.; Schaefer, R.; Seyd, J.; Albrecht, M.; Girt, E.

Abstract

The structural and magnetic properties of sputter-deposited Fe100−xRux films were studied for x < 50. The crystal structure of Fe100−xRux is shown to be predominantly body-centered cubic for x < 13 and to undergo a gradual transition to hexagonal close-packed in the Ru concentration range 13 < x < 20. Magnetic measurements indicate that the addition of Ru to Fe gives rise to a noncollinear magnetic alignment between Fe atoms in the body-centered cubic FeRu alloys, while the hexagonal close-packed FeRu alloys exhibit paramagnetic behavior. A simple atomistic model was used to show that the competition between ferromagnetic coupling of neighboring Fe atoms and antiferromagnetic coupling of Fe atoms across Ru atoms in cubic FeRu structures can induce noncollinear magnetic order. Magnetic multilayer structures used in thin-film magnetic devices make extensive use of both Fe and Ru layers. Our results reveal that the presence of even a small amount of Ru in Fe influences the magnetic order of Fe, which could impact the performance of these devices.

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Permalink: https://www.hzdr.de/publications/Publ-39679


Magnetic nanomembranes: from soft robotics to eco-sustainable magnetoelectronics

Makarov, D.

Abstract

Composites consisting of magnetic fillers in polymers and elastomers enable new types of applications in soft robotics, reconfigurable actuation and sensorics. In particular, soft-bodied robots emerge as the closest synthetic system analogous to living organisms mimicking their mechanical behavior and going beyond in performance. We will introduce lightweight, durable, untethered and ultrafast soft-bodied robots that can walk, swim, levitate, transport cargo, and perform collaborative tasks being driven using magnetic far fields [1,2] and near fields [3,4]. Reconfigurable magnetic origami actuators [2] can be equipped with ultrathin magnetosensitive e-skins [5], which help to assess the magnetic state of the actuator (magnetized vs. non-magnetized), decide on its actuation pattern and control sequentiality and quality of the folding process. The on-board sensing adds awareness to soft-bodied magnetic actuators enabling them to act and be controlled similar to conventional robotic devices [6].
Magnetic composites can be readily used to realise not only actuators but also magnetic field sensors [7]. We demonstrate that printed magnetoelectronics can be stretchable, skin-conformal, capable of detection in low magnetic fields and withstand extreme mechanical deformations [8,9]. We feature the potential of our skin-conformal sensors in augmented reality settings [10,11], where a sensor-functionalized finger conducts remote and touchless control of virtual objects manageable for scrolling electronic documents and zooming maps under tiny permanent magnet [8].
Furthermore, we put forth technology to realise magnetic field sensors, which can be printed and self-heal upon mechanical damage [12]. This opens exciting perspectives for magnetoelectronics in smart wearables, interactive printed electronics and motivates further explorations towards the realisation of recyclable magnetoelectronics [13]. For the latter, we will discuss eco-sustainable, namely biocompatible and biodegradable magneto sensitive devices, which can help to minimise electronic waste and bring magnetoelectronics to new application fields in medical implants and health monitoring [6].

[1] X. Wang et al., Untethered and ultrafast soft-bodied robots. Commun. Mater. 1, 67 (2020).
[2] M. Ha et al., Reconfigurable magnetic origami actuators with on-board sensing for guided assembly. Adv. Mater. 33, 2008751 (2021).
[3] M. Richter et al., Locally addressable energy efficient actuation of magnetic soft actuator array systems. Advanced Science 2302077 (2023).
[4] L. Masjosthusmann et al., Miniaturized variable stiffness gripper locally actuated by magnetic fields. Advanced Intelligent Systems 6, 2400037 (2024).
[5] G. S. Canon Bermudez et al., Magnetosensitive e-skins for interactive devices. Adv. Funct. Mater. (Review) 31, 2007788 (2021).
[6] E. S. Oliveros Mata et al., Magnetically aware actuating composites: Sensing features as inspiration for the next step in advanced magnetic soft robotics. Phys. Rev. Appl. (Review) 20, 060501 (2023).
[7] L. Guo et al., Printable magnetoresistive sensors: A crucial step toward unconventional magnetoelectronics. Chinese Journal of Structural Chemistry (Review) 100428 (2024).
[8] M. Ha et al., Printable and stretchable giant magnetoresistive sensors for highly compliant and skin-conformal electronics. Adv. Mater. 33, 2005521 (2021).
[9] E. S. Oliveros Mata et al., Dispenser printed bismuth-based magnetic field sensors with non-saturating large magnetoresistance for touchless interactive surfaces. Adv. Mater. Technol. 7, 2200227 (2022).
[10] J. Ge et al., A bimodal soft electronic skin for tactile and touchless interaction in real time. Nature Communications 10, 4405 (2019).
[11] P. Makushko et al., Flexible magnetoreceptor with tunable intrinsic logic for on-skin touchless human-machine interfaces. Adv. Funct. Mater. 31, 2101089 (2021).
[12] R. Xu et al., Self-healable printed magnetic field sensors using alternating magnetic fields. Nature Communications 13, 6587 (2022).
[13] X. Wang et al., Printed magnetoresistive sensors for recyclable magnetoelectronics. J. Mater. Chem. A 12, 24906 (2024).

Keywords: flexible magnetic field sensors; shapeable magnetoelectronics; printed magnetoelectronics; soft magnetic composites; magnetic soft robots

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  • Invited lecture (Conferences)
    The 5th China New Materials Industry Development Conference, 16.-18.10.2024, Wuhan, China

Permalink: https://www.hzdr.de/publications/Publ-39678


Flow optimized membraneless alkaline water electrolysis

Rox, H.; Schoppmann, K.; Gatter, J.; Frense, E.; Yang, X.; Rüdiger, F.; Fröhlich, J.; Eckert, K.

Abstract

Highly simplified electrolyzer designs in the form of a membraneless alkaline electrolyzer (MAEL) allow higher current densities compared to conventional designs and result as well in lower capital expenditures. In addition, MAELs provide very good access to the electrodes, making them ideal for research to better understand bubble formation and detachment. Since there is no membrane or diaphragm to separate the products, H2 and O2, the cell design to direct the electrolyte flow is critical.

Using CFD and current simulations, an optimized cell geometry was developed to ensure constant conditions for the water splitting reaction over the entire electrode. Particle Image Velocimetry and Shadowgraphy were used to systematically study the influence of the electrolyte flow as driving force for an effective H2 and O2 separation. It is shown that below a critical Recrit the evolving bubbles are stuck on the porous electrodes and lead to a blockage of electrochemical active sites as well as to an increase of the cell potential. On the other hand, high gas purity and overall efficiency were observed at the optimal flow rate to current density ratio. Thus, the present study proves the concept of the newly developed membraneless electrolyzer.

Keywords: Alkaline electrolysis; Membraneless electrolyzer; Flow-through electrode; Shadowgraphy; Particle image velocimetry

Involved research facilities

  • Data Center
  • Lecture (Conference)
    16th International Conference on Gas–Liquid and Gas–Liquid–Solid Reactor Engineering, 02.-05.09.2024, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-39676


Mineral chemistry of the Geyer SW tin skarn deposit: understanding variable fluid/rock ratios and metal fluxes

Gutzmer, J.; Meyer, N.; Burisch, M.; Krause, J.; Scheibert, H.; Markl, G.

Abstract

The Geyer tin skarn in the Erzgebirge, Germany, comprises an early skarnoid stage (stage I, ~ 320 Ma) and a younger
metasomatic stage (stage II, ~ 305 Ma), but yet, the source and distribution of Sn and the physicochemical conditions
of skarn alteration were not constrained. Our results illustrate that contact metamorphic skarnoids of stage I contain
only little Sn. REE patterns and elevated concentrations of HFSE indicate that garnet, titanite and vesuvianite of stage I
formed under rock-buffered conditions (low fluid/rock ratios). Prograde assemblages of stage II, in contrast, contain two
generations of stanniferous garnet, titanite-malayaite and vesuvianite. Oscillation between rock-buffered and fluid-buffered
conditions are marked by variable concentrations of HFSE, W, In, and Sn in metasomatic garnet. Trace and REE element
signatures of minerals formed under high fluid/rock ratios appear to mimic the signature of the magmatic-hydrothermal
fluid which gave rise to metasomatic skarn alteration. Concomitantly with lower fluid-rock ratio, tin was remobilized
from Sn-rich silicates and re-precipitated as malayaite. Ingress of meteoric water and decreasing temperatures towards
the end of stage II led to the formation of cassiterite, low-Sn amphibole, chlorite, and sulfide minerals. Minor and trace
element compositions of cassiterite do not show much variation, even if host rock and gangue minerals vary significantly,
suggesting a predominance of a magmatic-hydrothermal fluid and high fluid/rock ratios. The mineral chemistry of major
skarn-forming minerals, hence, records the change in the fluid/rock ratio, and the arrival, distribution, and remobilization
of tin by magmatic fluids in polyphase tin skarn systems.

Keywords: Erzgebirge; Tin skarn; Garnet; Cassiterite; Mineral chemistry

Permalink: https://www.hzdr.de/publications/Publ-39675


Data publication: Strong transient magnetic fields induced by THz-driven plasmons in graphene disks

Han, J. W.; Sai, P.; But, D.; Uykur, E.; Winnerl, S.; Kumar, G.; Chin, M. L.; Myers-Ward, R. L.; Dejarld, M. T.; Daniels, K. M.; Murphy, T. E.; Knap, W.; Mittendorff, M.

Abstract

In the zip file all metadata and raw data of experiements and simulations are collected and sorted into different folders

Keywords: Transient magnetic fields; Faraday rotation; Graphene; Plasmonics

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  • F-ELBE

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Permalink: https://www.hzdr.de/publications/Publ-39665


Electronic-Structure Interpretation: How Much Do We Understand Ce L3 XANES?

Kvashnina, K.

Abstract

Historically, cerium has been attractive for pharmaceutical and industrial applications. The cerium atom has the unique ability to cycle between two chemical states (Ce(III) and Ce(IV)) and drastically adjust its electronic configuration: [Xe] 4f15d16s2 in response to a chemical reaction. Understanding how electrons drive chemical reactions is an important topic. The most direct way of probing the chemical and electronic structure of materials is by X-ray absorption spectroscopy (XAS) or X-ray absorption near-edge structure (XANES) in high energy resolution fluorescence detection (HERFD) mode. Such measurements at the Ce L3 edge have the advantage of a high penetration depth, enabling in-situ reaction studies in a time-resolved manner and investigation of material production or material performance under specific conditions. But how much do we understand Ce L3 XANES? This article provides an overview of the information that can be extracted from experimental Ce L3 XAS/XANES/HERFD data. A collection of XANES data recorded on various cerium systems in HERFD mode is presented here together with detailed discussions on data analysis and the current status of spectral interpretation, including electronic structure calculations.

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Permalink: https://www.hzdr.de/publications/Publ-39658


Hydrothermal synthesis of (Zr,U)SiO4 : an efficient pathway to incorporate uranium into zircon

Estevenon, P.; Barral, T.; Avallone, A.; Jeffredo, M.; de la Hos, A.; Strzelecki, A.; Le Goff, X.; Szenknect, S.; Kvashnina, K.; Moisy, P.; Podor, R.; Guo, X.; Dacheux, N.

Abstract

he preparation of synthetic (Zr,U)SiO4 solid solution is challenging, as the conventional high-temperature
solid-state method limits the solubility of uranium (4 ± 1 mol%) in the orthosilicate phase due to its
thermodynamic instability. However, these compounds are of great interest as a result of (Zr,U)SiO4 solid
solutions, with uranium contents exceeding this concentration, being observed as corium phases formed
during nuclear accidents. It has been identified that hydrothermal synthesis pathways can be used for the
formation of the metastable phase, such as USiO4 . The investigation carried out in this study has indeed
led to the confirmation of metastable (Zr,U)SiO4 compounds with high uranium contents being formed. It
was found that (Zr,U)SiO4 forms a close-to-ideal solid solution with uranium loading of up to 60 mol% by
means of hydrothermal treatment for 7 days at 250 °C, at pH = 3 and starting from an equimolar reactant
concentration equal to 0.2 mol L−1 . A purification procedure was developed to obtain pure silicate com-
pounds. After purification, these compounds were found to be stable up to 1000 °C under an inert atmo-
sphere (argon). The characterisation methods used to explore the synthesis and thermal stability included
powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) and Raman spectroscopies, scanning
electron microscopy (SEM) and thermogravimetric analysis (TGA).

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Permalink: https://www.hzdr.de/publications/Publ-39657


Efficient removal of succinic acid by continuous hydrodynamic cavitation combined with ozone and side influent injection

Huaccallo Aguilar, Y.; Kumar, A.; Meier, M.; Paul Lerch, A.; Reinecke, S.

Abstract

Micropollutants (MPs) encompass a range of human-made pollutants present in trace amounts in environmental systems. MPs include pharmaceuticals, personal care products, pesticides, persistent organic pollutants, micro- and nano-plastics, and artificial sweeteners, all posing ecological risks. Conventional municipal wastewater treatment methods often face challenges in completely removing MPs due to their chemical characteristics, stability, and resistance to biodegradation. In this research, a novel Advanced Oxidation Process, combining hydrodynamic cavitation (HC) with dissolved ozone (O3), was employed to effectively degrade succinic acid (SA), a representative ozone-resistant compound. The HC/O3 process was run to treat different synthetic effluents, focusing on evaluating the influence of O3-to-total organic carbon (TOC) ratio, cavitation number (Cv) and O3 dosage. Notably, the results from a series of 14 experiments highlighted the critical significance of a low O3-to-TOC ratio value of 0.08 mg/mg and Cv value of 0.056 in HC for achieving efficient SA removal of 41.2% from an initial SA solution (106.3 mg/L). Regarding a series of four proof-of-concept experiments and their replications, the average TOC removal reached 62% when treating wastewater treatment plant effluent spiked with SA. This significant removal rate was achieved under initial conditions: Cv of 0.02, O3-to-TOC ratio set at 0.77 mg/mg, TOC concentration of 47.7 mg/L, 106 mg/L of SA, and a temperature of 25ºC. Notably, the electrical energy per order required for the 62% reduction in TOC was a modest 12.5 kWh/m3/order, indicating the potential of the continuous HC/O3 process as a promising approach for degrading a wide range of MPs.

Keywords: Cavitation number; ozone-resistant substances; energy consumption; wastewater; AOP; mineralization

Permalink: https://www.hzdr.de/publications/Publ-39656


Electrical Conductivity of Warm Dense Hydrogen from Ohm's Law and Time-Dependent Density Functional Theory

Ramakrishna, K.; Lokamani, M.; Cangi, A.

Abstract

Understanding the electrical conductivity of warm dense hydrogen is critical for both fundamental physics and applications in planetary science and inertial confinement fusion. We demonstrate how to calculate the electrical conductivity using the continuum form of Ohm's law, with the current density obtained from real-time time-dependent density functional theory. This approach simulates the dynamic response of hydrogen under warm dense matter conditions, with temperatures around 30,000 K and mass densities ranging from 0.02 to 0.98 g/cc. We systematically address finite-size errors in real-time time-dependent density functional theory, demonstrating that our calculations are both numerically feasible and reliable. Our results show good agreement with other approaches, highlighting the effectiveness of this method for modeling electronic transport properties from ambient to extreme conditions.

Keywords: Electronic structure; Density functional theory; Time-dependent density functional theory; Electrical conductivity; Warm dense matter; Hydrogen

Permalink: https://www.hzdr.de/publications/Publ-39653


Advances in drop and bubble profile analysis tensiometry

Javadi, A.; Liggieri, L.; Aksenenko, E. V.; Gochev, G. G.; Miller, R.

Abstract

Profile analysis tensiometry (PAT) with drops and bubbles is a successful methodology to characterize liquid–fluid interfaces. Questions about the most suitable size of drops and bubbles have been solved now on the basis of dimensionless numbers. The consideration of the standard deviation between measured and calculated liquid profiles as a sensitive measure for the applicability of PAT provides a tool for its correct use. For solutions of highly surface-active compounds, bulk depletion effects can cause systematic errors in the analysis of adsorption kinetics, equations of state, and the visco-elastic interfacial behavior of liquid adsorption layers. Great progress has been made in measurements of interfacial dilational rheology with large amplitude perturbations providing additional information about structure and dynamics of complex adsorption layers. Also, first attempts are successfully made to use artificial intelligence (AI) to enhance the efficiency of PAT applications. Thus, PAT has established a solid position in surface science.

Keywords: Dilational interfacial visco-elasticity; Drop profile analysis tensiometry; Gauss-Laplace equation

Permalink: https://www.hzdr.de/publications/Publ-39651


Antiferromagnetic nanoscale bit arrays of magnetoelectric Cr2O3 thin films

Rickhaus, P.; Pylypovskyi, O.; Seniutinas, G.; Borras, V.; Lehmann, P.; Wagner, K.; Zaper, L.; Prusik, P.; Makushko, P.; Veremchuk, I.; Kosub, T.; Hübner, R.; Sheka, D. D.; Maletinsky, P.; Makarov, D.

Abstract

Magnetism of oxide antiferromagnets (AFMs) has been studied in single crystals and extended thin films. The properties of AFM nanostructures still remain underexplored. Here, we report on the fabrication and magnetic imaging of granular 100-nm-thick magnetoelectric \ch{Cr2O3} films patterned in circular bits with diameters ranging from 500 down to 100\,nm. With the change of the lateral size, the domain structure evolves from a multidomain state for larger bits to a single domain state for the smallest bits. Based on spin-lattice simulations, we show that the physics of the domain pattern formation in granular AFM bits is primarily determined by the energy dissipation upon cooling, which results in motion and expelling of AFM domain walls of the bit. Our results provide a way towards the fabrication of single domain AFM-bit-patterned memory devices and the exploration of the interplay between AFM nanostructures and their geometric shape.

Keywords: Cr2O3; bit memory

Permalink: https://www.hzdr.de/publications/Publ-39649


GMP-compatible production of adapter CAR T cells using a CliniMACS Prodigy®

Jutrzenka-Trzebiatowski, A.; Daglar, C.; Arndt, C.; Rodrigues Loureiro, L. R.; Bachmann, M.; Feldmann, A.

Abstract

Over the last decade chimeric antigen receptor (CAR) T cell immunotherapy demonstrated great success in hematological malignancies. On the downside, however, these therapies are also accompanied by various adverse events, such as cytokine release syndrome or on-target off-tumor effects. To overcome these hurdles, we have developed switchable adapter CAR systems, namely the UniCAR and RevCAR technology. T cells modified to express such adapter CARs can be not only directed against a certain tumor specific target but also reversibly switched ON and OFF allowing a steerable therapy. So far, adapter CAR T cells potently eradicated tumor cells of various entities both in vitro and in vivo. For an application in patients, adapter CAR T cells need to be produced according to GMP requirements. In that regard, the CliniMACS Prodigy® represents a powerful closed-system manufacturing instrument enabling an automated production process with reduced risk for contamination and hands-on time. Here, we present successful generation of adapter CAR T cells using a CliniMACS Prodigy® which yielded in high transduction rates and cell numbers. Moreover, CliniMACS Prodigy® produced adapter CAR T cells potently killed tumor cells in a steerable manner demonstrating their high potential for a clinical application.

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    2024 Annual Meeting - Study Group Tumor Immunology, 08.10.2024, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-39647


Years: 2024 2023 2022 2021 2020 2019 2018 2017 2016


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