Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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41809 Publications

Indirect evidence for elemental hydrogen in laser-compressed hydrocarbons

Kraus, D.; Vorberger, J.; Hartley, N. J.; Lütgert, J.; Rödel, M.; Chekrygina, D.; Döppner, T.; van Driel, T.; Falcone, R. W.; Fletcher, L. B.; Frydrych, S.; Galtier, E.; Gericke, D. O.; Glenzer, S. H.; Granados, E.; Inubushi, Y.; Kamimura, N.; Katagiri, K.; Macdonald, M. J.; Mackinnon, A. J.; Matsuoka, T.; Miyanishi, K.; McBride, E. E.; Nam, I.; Neumayer, P.; Ozaki, N.; Pak, A.; Ravasio, A.; Saunders, A. M.; Schuster, A. K.; Stevenson, M. G.; Sueda, K.; Sun, P.; Togashi, T.; Voigt, K.; Yabashi, M.; Yabuuchi, T.

Abstract

We demonstrate a significantly simplified experimental approach for investigating liquid metallic hydrogen, which is crucial to
understand the internal structure and evolution of giant planets. Plastic samples were shockcompressed and then probed by
short pulses of X-rays generated by free electron lasers. By comparison with ab initio simulations, we provide indirect
evidence for the creation of elemental hydrogen in shock-compressed plastics at ∼150GPa and ∼5,000K and thus in a
regime where hydrogen is predicted to be metallic. Being the most common form of condensed matter in our solar system,
and ostensibly the simplest of all elements, hydrogen is the model case for many theoretical studies and we provide a new
possibility to benchmark models for conditions with extreme pressures and temperatures. Moreover, this approach will also
allow to probe the chemical behavior of metallic hydrogen in mixture with other elements, which, besides its importance for
planetary physics, may open up promising pathways for the synthesis of new materials.

Keywords: hydrogen; metallic hydrogen; warm dense matter; x-ray diffraction; x-ray free electron laser

Permalink: https://www.hzdr.de/publications/Publ-37150


Actinide(IV) Complexes Containing 2-Mercaptopyridyl

Balas, J.; Urbank, C.; Kaden, P.; März, J.; Gericke, R.

Abstract

Actinides (An) play an important role in chemical research and environmental science related to the nuclear industry or nuclear waste repositories. Investigating their coordination chemistry can function as a tool to obtain fundamental understanding of actinide binding. Due to the radiotoxicity of actinide complexes, special care in handling those material is needed in form of working in a controlled area lab. Therefore, the understanding of complexation properties of the actinides, in particular the transuranium (TRU) elements, is lacking behind those of the d- or 4f-elements.
For the early actinides possible oxidation states typically range from +II to +VII. A suitable approach to explore fundamental physico-chemical properties of the actinides is to study series of isostructural An compounds in which the An is in the same oxidation state. Therefore, our investigations are directed towards the synthesis of actinide complexes (An = Th, U, Np, and Pu) with the f-element in the oxidation state IV, the dominant oxidation state particularly under anoxic conditions. Observed changes in e.g. the binding situation or magnetic effects along such series deliver insight into the elements’ unique electronic properties mainly originating from the f-electrons. One important question in the field of An chemistry is the degree of “covalency” in compounds across the An series, which may be addressed by systematic studies on series of An compounds, including transuranium (TRU) elements.
An complexes using ambidentate ligand systems can give valuable information on covalency differences between soft and hard donor atoms in one complex system. We therefore chose the 2-mercaptopyridyl ligand system (PyS) as monoanionic ambidentate S,N-moiety. Due to possible resonance structures in the ligand backbone, the negative charge can be distributed over both donor atoms. This leaves sufficient flexibility for PyS to coordinate to the actinide atom in a S- or N-monodentate or S,N-chelating manner. We synthesized a series of PyS-containing Th, U, Np, and Pu complexes and compare their structural and spectroscopic characteristics along the early actinides. These results are used as a basis to further analyze bonding trends along the actinide series by means of quantum chemical calculations.
From the results, trendlines along the actinides were obtained, which shed some light in the ongoing debate of covalency in actinide bonding.

Keywords: 2-Mercaptopyridyl; actinides; chemical bonding; synthesis; single crystal X-ray diffraction; NMR spectroscopy

Involved research facilities

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  • Lecture (Conference)
    Actinides 2023, 05.-08.06.2023, Colorado, USA

Permalink: https://www.hzdr.de/publications/Publ-37149


Data for publication in Nature Communications: Search for 22Na in novae supported by a novel method for measuring femtosecond nuclear lifetimes

Fougères, C.; de Oliveira Santos, F.; José, J.; Michelagnoli, C.; Clément, E.; Kim, Y. H.; Lemasson, A.; Guimarães, V.; Barrientos, D.; Bemmerer, D.; Benzoni, G.; Boston, A. J.; Böttger, R.; Boulay, F.; Bracco, A.; Celikovic, I.; Cederwall, B.; Ciemala, M.; Delafosse, C.; Domingo-Pardo, C.; Dudouet, J.; Eberth, J.; Fülöp, Z.; González, V.; Gottardo, A.; Goupil, J.; Hess, H.; Jungclaus, A.; Kaskas, A.; Korichi, A.; Lenzi, S. M.; Leoni, S.; Li, H.; Ljungvall, J.; Lopez-Martens, A.; Menegazzo, R.; Mengoni, D.; Million, B.; Mrazek, J.; Napoli, D. R.; Navin, A.; Nyberg, J.; Podolyak, Z.; Pullia, A.; Quintana, B.; Ralet, D.; Redon, N.; Reiter, P.; Rezynkina, K.; Saillant, F.; Salsac, M. D.; Sánchez-Benítez, A. M.; Sanchis, E.; Senyigit, M.; Siciliano, M.; Smirnova, N. A.; Sohler, D.; Stanoiu, M.; Theisen, C.; Valiente-Dobón, J. J.; Ujic, P.; Zielinska, M.

Abstract

https://u.ganil-spiral2.eu/10.26143/GANIL-2016-E710.html

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-37148


Strömungsbeeinflussung durch Lorentzkräfte

Nash, W.; Weier, T.

Abstract

Im Zusammenspiel magnetischer und elektrischer Felder entstehen
elektromagnetische Kräfte. Deren praktische Anwendung z. B. in Elektromotoren ist aus unserem Alltag nicht mehr wegzudenken.
Elektromagnetische Kräfte sind aber auch in der Lage, leitfähige Flüssigkeiten, wie Elektrolyte und Metallschmelzen, kontaktlos zu beeinflussen.
Die Vielfalt an Strömungskonfigurationen, die mit einfachen Permanentmagneten in einer Elektrolysezelle einstellbar sind, wird im Experiment
demonstriert.

Keywords: Lorentz force; flow control; PIV

  • Poster
    Lange Nacht der Wissenschaften, 30.06.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37147


Energielandschaft und Speicher im Wandel der Zeiten

Weier, T.

Abstract

Energie ist auf vielfltige Weise mit dem Leben verknüpft. Im Laufe der Geschichte dominierten unterschiedliche Energieträger. Der Vortrag nimmt sie unter die Lupe und zeigt den Wandel ihrer Nutzung und die damit verbundenen Konsequenzen. Ein Schwerpunkt ist die im Horizon 2020 Projekt SOLSTICE entwickelte Speichertechnologie.

Keywords: liquid metal battery; SOLSTICE; ZEBRA; deforestation; prime movers; power density; material demand

  • Lecture (Conference)
    Lange Nacht der Wissenschaften, 30.06.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37146


Flüssigmetallbatterien als Pufferspeicher für grüne Energie

Weier, T.

Abstract

Die geplante Umstellung des Energiesystems auf fluktuierende Erzeuger zieht einen immensen Bedarf an Speichern nach sich, um Angebot und Nachfrage auszugleichen. Der Vortrag stellt verschiedene Arten von Flüssigmetallbatterien vor, die derzeit mit dem Ziel einer ökonomischen stationären Energiespeicherung entwickelt werden.

Keywords: liquid metal battery; ZEBRA; SOLSTICE

  • Lecture (Conference)
    Matchmaking Energie, 30.06.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37145


Pufferspeicher für „grüne“ Energie - Potential der Flüssigmetallbatterie

Weier, T.

Abstract

Die geplante Umstellung des Energiesystems auf fluktuierende Erzeuger zieht einen immensen Bedarf an Speichern nach sich, um Angebot und Nachfrage auszugleichen. Der Vortrag stellt verschiedene Arten von Flüssigmetallbatterien vor, die derzeit mit dem Ziel einer ökonomischen stationären Energiespeicherung entwickelt werden.

Keywords: liquid metal battery; ZEBRA; SOLSTICE

  • Invited lecture (Conferences)
    Energy Saxony Summit 2023, 22.06.2023, Freiberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37144


Numerical investigation on steam condensation and heat transfer in an emergency condenser tube with the thermo-hydraulic system code ATHLET: Post-test simulation of a series of COSMEA tests

Jobst, M.; Schäfer, F.; Kliem, S.

Abstract

The aim of the PANAS project, sponsored by the German Federal Ministry of Education and Research, was an in-depth analysis of the energy transfer processes of condensation and evaporation in inclined pipes at high and low system pressures, as they are used in passive residual heat removal systems for GEN III/III+ nuclear power plants. Passive residual heat removal systems play an important role in controlling accidents in the design basis, but also in beyond design basis accidents. By application of innovative measurement technologies, it was possible to study condensation and evaporation processes with an unprecedented temporal and spatial resolution, providing a new and unique database for further development and validation of CFD and system codes. With the work carried out in the project the experimental database was significantly expanded and an important contribution was made to provide sufficiently validated numerical tools, which allow authorities and experts to evaluate new reactor concepts and nuclear power plants with passive
residual heat removal systems.
Based on a series of COSMEA tests conducted in 2020 and 2021, the paper presents results of post-test simulations performed with a standard version of ATHLET as well as with an improved version of the code. After an overview on the research topics, the paper discusses the heat transfer phenomena in an emergency condenser pipe, the corresponding physical models implemented in ATHLET and the input deck developed to simulate the COSMEA tests. First results of the simulations with the standard version of ATHLET showed a significant underestimation of the transferred heat flow, an overestimation of the condensate outlet temperature and, depending on the experimental conditions, an underestimation or overestimation of the condensation rate. An in-depth analysis of the results helps to identify possible reasons for the deviations. The second set of simulations with an improved version of the code shows much better agreement with the experimental data. The corresponding part of the paper describes the modifications to the source code, the physical reasons behind these modifications and the improvements obtained with the updated models.

Keywords: Condensation heat transfer; passive safety systems; system code development; ATHLET; AC2

Involved research facilities

  • TOPFLOW Facility

Permalink: https://www.hzdr.de/publications/Publ-37143


Search for 22Na in novae supported by a novel method for measuring femtosecond nuclear lifetimes

Fougères, C.; de Oliveira Santos, F.; José, J.; Michelagnoli, C.; Clément, E.; Kim, Y. H.; Lemasson, A.; Guimarães, V.; Barrientos, D.; Bemmerer, D.; Benzoni, G.; Boston, A. J.; Böttger, R.; Boulay, F.; Bracco, A.; Celikovic, I.; Cederwall, B.; Ciemala, M.; Delafosse, C.; Domingo-Pardo, C.; Dudouet, J.; Eberth, J.; Fülöp, Z.; González, V.; Gottardo, A.; Goupil, J.; Hess, H.; Jungclaus, A.; Kaskas, A.; Korichi, A.; Lenzi, S. M.; Leoni, S.; Li, H.; Ljungvall, J.; Lopez-Martens, A.; Menegazzo, R.; Mengoni, D.; Million, B.; Mrazek, J.; Napoli, D. R.; Navin, A.; Nyberg, J.; Podolyak, Z.; Pullia, A.; Quintana, B.; Ralet, D.; Redon, N.; Reiter, P.; Rezynkina, K.; Saillant, F.; Salsac, M. D.; Sánchez-Benítez, A. M.; Sanchis, E.; Senyigit, M.; Siciliano, M.; Smirnova, N. A.; Sohler, D.; Stanoiu, M.; Theisen, C.; Valiente-Dobón, J. J.; Ujic, P.; Zielinska, M.

Abstract

Classical novae are thermonuclear explosions in stellar binary sys- tems, and important sources of 26Al and 22Na. While γ rays from the decay of the former radioisotope have been observed throughout the Galaxy, 22Na remains untraceable. Its half-life (2.6 yr) would allow the observation of its 1.275 MeV γ-ray line from a cosmic source. However, the prediction of such an observation requires good knowl- edge of its nucleosynthesis. The 22Na(p,γ)23Mg reaction remains the only source of large uncertainty about the amount of 22Na ejected. Its rate is dominated by a single resonance on the short-lived state at 7785.0(7) keV in 23Mg. Here, a combined analysis of particle-particle correlations and velocity-difference profiles is proposed to measure femtosecond nuclear lifetimes. The application of this method to the study of the 23Mg states, places strong limits on the amount of 22Na produced in novae and constrains its detectability with future space-borne observatories.

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-37142


Improving susceptibility of neuroendocrine tumors to radionuclide therapies: personalized approaches towards complementary treatments

Richter, S.; Steenblock, C.; Lemm, S.; Ziegler, C. G.; Bechmann, N.; Nölting, S.; Pietzsch, J.; Ullrich, M.

Abstract

Radionuclide therapies are an important tool for the management of patients with neuroendocrine tumors (NETs). Especially [131I]MIBG and [177Lu]Lu-DOTA-TATE are routinely used for the treatment of a subset of NETs, including phechromocytomas, paragangliomas and gastroenteropancreatic tumors. Some patients suffering from other forms of NETs, such as medullary thyroid carcinoma or neuroblastoma, were shown to respond to radionuclide therapy; however, no general recommendations exist. Although [131I]MIBG and [177Lu]Lu-DOTA-TATE can delay disease progression and improve quality of life, complete remissions are achieved rarely. Hence, better individually tailored combination regimes are required. This review summarizes currently applied radionuclide therapies in the context of NETs and informs about recent advances in the development of theranostic agents that might enable targeting subgroups of NETs that previously did not respond to [131I]MIBG or [177Lu]Lu-DOTA-TATE. Moreover, molecular pathways involved in NET tumorigenesis and progression that mediate features of radioresistance and are particularly related to the stemness of cancer cells are discussed. Pharmacological inhibition of such pathways might result in radiosensitization or general complementary antitumor effects in patients with certain genetic, transcriptomic, or metabolic characteristics. Finally, we provide an overview of approved targeted agents that might be beneficial in combination with radionuclide therapies in the context of a personalized molecular profiling approach.

Permalink: https://www.hzdr.de/publications/Publ-37141


First HELIPORT Workshop 2023 - Book of Abstracts

Kessler, A.; Ponomaryov, A.; Mistry, A. K.; Barty, A.; Irman, A.; Schneidewind, A.; Schuller, B.; Gou, B.; Edward Marre, B.; Murphy, B.; Becker, C.; Hundt, C.; Lee, C.-L.; Gutt, C.; Schneide, C.; Engelhardt, C.; Pape, D.; Rau, F.; Maas, F.; Schreiber, F.; Bethke, F.; Guenther, G.; Juckeland, G.; Pruß, G.; Schlenvoigt, H.-P.; Deinert, J.-C.; Grunwaldt, J.-D.; Kelling, J.; Hein, J.; Sperling, J.; Schwarz, K.; Tippey, K. E.; Steinmeier, L.; Amelung, L.; Christoph Kaluza, M.; Lokamani, M.; Hanisch, M.; Voigt, M.; Bussmann, M.; Kurzweil, M.; Hoffmann, N.; Wagner, N.; Knodel, O.; Mannix, O.; Ufer, P.; Baumgärtel, P.; Müller-Pfefferkorn, R.; Baunack, S.; Busch, S.; Sachse, S.; Starke, S.; Kovalev, S.; Vadilonga, S.; Bock, S.; Müller, S.; Schoebel, S.; Gruber, T.; Kluge, T.; Unruh, T.; Lohstroh, W.; Horn, W.

Abstract

In our HELIPORT workshop, we provided insights into our project and share our results. In addition, we would like to provide a platform for the presentation of similar projects, as well as extensions or integrations from the surrounding research areas. The overall goal of the workshop is bringing together different institutions with similar challenges and establishing a community around our HELIPORT project.
We therefore encouraged our community to submit an abstract for a talk or poster. The submissions are dedicated to four thematic points:

  • HELIPORTuse-cases,
  • Scientificprojectandmetadatamanagement, • Experiment-specificandoverallmetadataand • Scientificworkflows.
HELIPORT (Helmholtz ScIentific Project WORkflow PlaTform) itself is a project funded by the Helmholtz Metadata Collaboration, and runs from July 2021 until June 2023. HELIPORT aims to make the entire life cycle of a scientific project findable, accessible, interoperable and reusable according to the FAIR principles. In particular, our data management solution deals with the areas from the generation of the data to the publication of primary research data, the workflows carried out and the actual research results. For this purpose, a concept was developed which shows the various essential components and their connections.

Keywords: Data Management; Metadata Management; Heliport; Helmholtz Metadata Collaboration; Computational Workflow

Permalink: https://www.hzdr.de/publications/Publ-37140


Data publication: Ultrafast Relaxation Dynamics of Spin-Density Wave Order in BaFe2As2 under High Pressures

Fotev, I.; Winnerl, S.; Aswartham, S.; Wurmehl, S.; Büchner, B.; Schneider, H.; Helm, M.; Pashkin, O.

Abstract

Raw pump-probe data for two Ba-122 DAC fillings used in the paper, photos of the samples inside the DAC, Matlab script for constructing the p-T plot of the SDW order

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Permalink: https://www.hzdr.de/publications/Publ-37139


Understanding electronic correlations in warm dense quantum plasmas

Dornheim, T.

Abstract

Warm dense matter (WDM)---an extreme state that is characterized by extreme densities and temperatures---has emerged as one of the most active frontiers in plasma physics and material science. In nature, WDM occurs in astrophysical objects such as giant planet interiors and brown dwarfs. In addition, WDM is highly important for cutting-edge technological applications such as inertial confinement fusion and the discovery of novel materials. In the laboratory, WDM is studied experimentally in large facilities around the globe, and new techniques have facilitated unprecedented insights. Yet, the interpretation of these experiments requires a reliable diagnostics based on accurate theoretical modeling, which is a notoriously difficult task [1]. In this work, I will give an overview of how we can use exact ab-initio path integral Monte Carlo (PIMC) simulations [2] together with thermal density functional theory (DFT) calculations to get new insights into the behavior of WDM. Moreover, I will show how switching to the imaginary time representation allows us to significantly improve the interpretation of X-ray Thomson scattering (XRTS) experiments, which are a key diagnostic for WDM [3]. Specifically, I will present a model-free temperature diagnostic [4] based on the well-known principle of detailed balance, but available for all wave numbers, and a new idea to directly extract the electron— electron static structure factor from an XRTS measurement [5]. As an outlook, I will show how new PIMC capabilities will allow to give us novel insights into electronic correlations in warm dense quantum plasmas, leading to unprecedented agreement between experiments [6] and theory.

[1] M. Bonitz et al., Physics of Plasmas 27, 042710 (2020)

[2] M. Böhme et al., Physical Review Letters 129, 066402 (2022)

[3] S. Glenzer and R. Redmer, Reviews of Modern Physics 81, 1625 (2009)

[4] T. Dornheim et al., Nature Communications 13, 7911 (2022)

[5] T. Dornheim et al., arXiv:2305.15305 (submitted)

[6] T. Döppner et al., Nature 618, 270-275 (2023)

  • Lecture (others)
    High Energy Density Science Center Seminars, 22.06.2023, Livermore, California, USA

Permalink: https://www.hzdr.de/publications/Publ-37138


First-principles modeling of electronic transport properties and physics-informed machine learning for electron dynamics

Cangi, A.

Abstract

In this talk, I will present our research on the application of time-dependent density functional theory (TDDFT) to model observables induced in matter under extreme conditions. Specifically, I will discuss the electron loss function in scattering experiments with X-ray free electron lasers [1] and the electrical conductivity in metals [2, 3]. Additionally, I will explore the potential of physics-informed neural networks for solving the time-dependent Kohn-Sham equations, which describe electron dynamics in response to incident electromagnetic waves [4].

[1] Z. Moldabekov, T. Dornheim, A. Cangi, Sci. Rep. 12, 1093 (2022).
[2] K. Ramakrishna, M. Lokamani, A. Baczewski, J. Vorberger, A. Cangi, Phys. Rev. B 107, 115131 (2023).
[3] K. Ramakrishna, M. Lokamani, A. Baczewski, J. Vorberger, A. Cangi, arXiv:2210.10132 (2022).
[4] K. Shah, P. Stiller, N. Hoffmann, A. Cangi, NeurIPS Machine Learning and the Physical Sciences, arXiv:2210.12522 (2022).

Keywords: materials science; atomic physics; density functional theory; transport properties; neural networks; electron dynamics

  • Invited lecture (Conferences)
    2023 TDDFT School & Workshop: Excited states and dynamics, 05.-08.07.2023, 195 University Ave, Newark, NJ 07102, United States

Permalink: https://www.hzdr.de/publications/Publ-37137


First-principles modeling of electronic transport properties and the prospects of machine learning the electronic structure of matter at scale

Cangi, A.

Abstract

In this talk, I will present two lines of our research. In the first part, I will discuss the application of time-dependent density functional theory (TDDFT) in modeling observables induced in matter under extreme conditions, such as the electron loss function relevant to scattering experiments with X-ray free electron lasers [1] and the electrical conductivity in metals [2]. In the second part, I will highlight our recent progress in leveraging Artificial Intelligence (AI) to enhance the efficiency of electronic structure calculations [3]. Specifically, I will focus on our efforts to accelerate Kohn-Sham density functional theory calculations at finite temperatures by integrating deep neural networks into the Materials Learning Algorithms framework [4,5]. Our results demonstrate significant improvements in calculation speed for metals up to their melting point. Additionally, our implementation of automated machine learning has led to substantial savings in computational resources for identifying optimal neural network architectures, paving the way for large-scale AI-driven investigations [6]. Lastly, I will present our latest breakthrough, showcasing the capability of neural-network-driven electronic structure calculations for systems containing over 100,000 atoms [7].

[1] Z. Moldabekov, T. Dornheim, A. Cangi, Sci. Rep. 12, 1093 (2022).
[2] K. Ramakrishna, M. Lokamani, A. Baczewski, J. Vorberger, A. Cangi, Phys. Rev. B 107, 115131 (2023).
[3] L. Fiedler, K. Shah, M. Bussmann, A. Cangi, Phys. Rev. Materials 6, 040301, (2022).
[4] 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, MALA, https://doi.org/10.5281/zenodo.5557254 (2021).
[5] J. A. Ellis, L. Fiedler, G. A. Popoola, N. A. Modine, J. A. Stephens, A. P. Thompson, A. Cangi, Phys. Rev. B 104, 035120 (2021).
[6] L. Fiedler, N. Hoffmann, P. Mohammed, G. A. Popoola, T. Yovell, V. Oles, J. A. Ellis, S. Rajamanickam, A. Cangi, Mach. Learn.: Sci. Technol. 3, 045008 (2022).
[7] L. Fiedler, N. A. Modine, S. Schmerler, D. J. Vogel, G. A. Popoola, A. P. Thompson, S. Rajamanickam, A. Cangi, Npj Comput. Mater., accepted (2023).

Keywords: density functional theory; electrical conductivity; machine learning; transport properties; neural networks; materials science; computational physics

  • Invited lecture (Conferences)
    High energy density science seminar series, 29.06.2023, 7000 East Ave, Livermore, CA 94550, United States

Permalink: https://www.hzdr.de/publications/Publ-37136


Definition of the neutronics benchmark of the NuScale-like core

Fridman, E.; Bilodid, Y.; Valtavirta, V.

Abstract

This paper defines a 3D full core neutronics benchmark which is based on the NuScale small modular reactor (SMR) concept. The paper provides a detailed description of the NuScale-like core, a list of expected outputs, and a reference solution to the benchmark exercises obtained with the Monte Carlo code Serpent.

The benchmark was developed in the framework of the Euratom McSAFER project and can be used for verification of computational chains dedicated to 3D full-core neutronics simulations of water cooled SMRs.

The paper is supplemented with a digital data set to ease the modeling process.

Keywords: NuScale; SMR; Serpent; Monte Carlo; benchmark

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Permalink: https://www.hzdr.de/publications/Publ-37135


Ultrafast Relaxation Dynamics of Spin-Density Wave Order in BaFe2As2 under High Pressures

Fotev, I.; Winnerl, S.; Aswartham, S.; Wurmehl, S.; Büchner, B.; Schneider, H.; Helm, M.; Pashkin, O.

Abstract

BaFe2As2 is the parent compound for a family of iron-based high-temperature superconductors as well as a prototypical example of the spin-density wave (SDW) system. In this study, we perform an optical pump-probe study of this compound to systematically investigate the SDW order across the pressure-temperature phase diagram. The suppression of the SDW order by pressure manifests itself by the increase of relaxation time together with the decrease of the pump-probe signal and the pump energy necessary for complete vaporization of the SDW condensate. We have found that the pressure-driven suppression of the SDW order at low temperature occurs gradually in contrast to the thermally-induced SDW transition. Our results suggest that the pressure-driven quantum phase transition in BaFe2As2 (and probably other iron pnictides) is continuous and it is caused by the gradual worsening of the Fermi-surface nesting conditions.

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Permalink: https://www.hzdr.de/publications/Publ-37134


Data publication: Equilibrium Taylor bubble in a narrow vertical tube with constriction

Maestri, R.; Radhakrishnakumar, S.; Bürkle, F.; Ding, W.; Büttner, L.; Czarske, J.; Hampel, U.; Lecrivain, G.

Abstract

Data used in the article Equilibrium Taylor bubble in a narrow vertical tube with constriction.

Compressed in the 7Z File:

Data: Values used for bubble velocity in Fig. 4 and values extracted from the wall shape in the different tubes;

Figures: All figures used in the publication;

Videos: Videos in mp4 or avi.

Keywords: Bubble dynamics; Interfacial flows; Deformation; Multiphase flows; Taylor bubbles.

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Permalink: https://www.hzdr.de/publications/Publ-37133


Automatic Tuning of the Spectral Shape of an Ultra-High-Intensity Laser system

Bethke, F.

Abstract

In laser wakefield acceleration, a laser pulse interacts with plasma to accelerate electrons.
These novel small-scale accelerators require an ultra-short, high-intensity laser system. The
intensity and its temporal distribution can be described by the spectrum of the laser. Initially,
this spectrum has the characteristics of a time-varying Gaussian-like shape with several smaller
peaks and fluctuations. Before the laser can be used in experiments, it must be amplified to
the desired intensities. If the initial spectrum is amplified, the uneven intensity distribution of
the Gaussian-like shape can lead to high intensities at the wavelengths at the corresponding
peak positions. These high intensities form a potential threat due to the amount of energy
present over a short period, which could lead to the loss and destruction of laboratory equip-
ment. Consequently, the spectrum must be equalized in gain. To achieve gain equalization,
the shape of the spectrum must be changed accordingly, subject to the time-varying unmodi-
fied initial spectrum.
One option for performing the spectral shaping is the ”Mazzler” device developed and con-
structed by the French companies, Fastlite and Amplitude technologies. This device can modify
an optical input beam in a flexible manner and be adjusted to complex settings. However, this
is currently performed by an proprietary feedback loop shipped with the device. Consequently,
the details and inner workings of this software are inaccessible. The feedback loop has only a
single mode of operation, which is the purposing of a single predefined spectral target. This
target is the equalization of the spectral gain, in which the intensities of the spectrum are
more evenly distributed, thereby allowing for better amplification. While this modification of
the spectrum is achieved by the feedback loop to a reliable and sufficient degree, multiple iter-
ations of the underlying algorithm are needed to reach the desired state. Since the execution
of each of these steps requires manual interaction, the question of a faster solution arises.
Approaching this task in a data-driven manner is a promising direction for achieving this, since
the corresponding methods allow utilization of already existing experience in the form of data,
gained by modifying spectra in the past. Unlike the current feedback loop, this would imply that
prior executions in previous optimization procedures were not forgotten, but used to build a
model capable of reaching the desired goal more quickly. Furthermore, a method capable of
this could potentially also be used to perform other modifications to the spectra, demonstrat-
ing promising features important for specific use cases such as laser wakefield acceleration.
The generation and optimization of settings for the Mazzler device with neural networks is
the major task introduced in this thesis. An actor-critic model with multiple adaptations of the
algorithm and the underlying models is presented and proposed as an novel approach to this
problem. These models are capable of optimizing in a large, continuous domain through the
exploration-based generation of data, enabling to reach states not present in any available
data. This makes them especially suitable for the optimization of Mazzler settings to modify
spectra in an unprecedented manner. Furthermore, extensive data-related processing to re-
strict the state and action-space of the method are investigated to enable stable operation
and improved efficiency of the hardware in the laboratory. Corresponding results gathered
over multiple days in the DRACO laser laboratory of HZDR are presented with the proposed
method controlling the Mazzler device. Additionally, since execution of these experiments re-
quires hardware interaction, an implementation of this functionality is presented.

Keywords: Machine Learning; Deep Learning; Reinforcement Learning; DRACO; Mazzler

Involved research facilities

  • Draco
  • Master thesis
    TU Dresden, 2023

Permalink: https://www.hzdr.de/publications/Publ-37132


Numerical study of flashing pipe flow using a TFM-PBM coupled method:Effect of interfacial heat transfer and bubble coalescence and breakup

Li, J.; Liao, Y.; Zhou, P.; Lucas, D.; Li, Q.

Abstract

In the present work, the two-fluid model (TFM) is coupled with the population balance model (PBM) to trace the spatial and temporal change of bubble size and interfacial area concentration (IAC) in flashing flows. The model is first validated for bubble growing in stagnant superheated liquid, and satisfactory predictions of the bubble size under low and moderate superheat are obtained. It is then applied to flashing pipe flows, which are characterized by low superheat and high turbulence intensities. The results show that in these cases, coalescence and breakup are important phenomena changing the bubble size distribution in addition to growth. The neglect of their contribution leads to a significant under-prediction of the bubble size and consequently over-prediction of IAC. In addition, choosing an appropriate closure for interfacial heat transfer coefficient (HTC) is another key point in flashing simulation. In high-Reynolds cases (e.g. Re > 10^6), the enhancement due to turbulence is nonnegligible.

Keywords: Flashing flow; Interfacial area concentration; Interfacial heat transfer; Two-fluid model; Population balance model

Involved research facilities

  • TOPFLOW Facility

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Permalink: https://www.hzdr.de/publications/Publ-37130


Nonlinear large-scale flow transition in a precessing cylinder and its potential for hydromagnetic dynamo action

Gundrum, T.; Kumar, V.; Pizzi, F.; Giesecke, A.; Stefani, F.; Eckert, S.

Abstract

n this paper, we present an experimental investigation that centers on exploring the fluid dynamics within a
precessing cylinder. Our research is part of the DRESDYN project at Helmholtz-Zentrum Dresden-Rossendorf,
specifically focusing on the precession dynamo experiment. The primary objective of our study is to examine how
different rotation configurations influence the dominant flow modes inside the precessing cylinder, specifically
considering the prograde and retrograde rotations. Our main focus lies on two significant flow modes: the directly
forced mode (m1, k1) and the non-geostrophic axisymmetric mode (m0, k2). These modes hold substantial potential
for precession-driven dynamo action. By analyzing the outcomes between the prograde and retrograde
configurations, we gain valuable insights into the prevailing flow patterns within the precessing cylinder.

Keywords: Precession; DRESDYN; modes; dynamo

Involved research facilities

  • DRESDYN
  • Contribution to proceedings
    14th International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering (ISUD 2023), 23.-25.10.2023, Kobe, Japan
    Proceedings of the 14th International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering (ISUD 2023)

Permalink: https://www.hzdr.de/publications/Publ-37129


Formation constant of the double salt CsCl·2NaCl·2H₂O(cr)

Bok, F.

Abstract

In the ternary system CsCl – NaCl – H₂O, at a temperature of 298.15 K, a double salt with the stoichiometric formula CsCl∙2NaCl∙2H₂O(cr) is known to be formed. This double salt and the anhydrous CsCl(cr) are the end-members of a solid solution. For the pure double salt, the solubility constant was determined. The obtained value were applied to calculate the solubility diagram also of the quaternary system CsCl – NaCl – KCl – H₂O and the quaternary-reciprocal system Cs⁺, Na⁺ || Cl⁻, SO₄²⁻ – H₂O. The solubility constant together with a solid solution between CsCl∙2NaCl∙2H₂O(cr) and CsCl(cr) were implemented in THEREDA, which extends the applicability of the existing cesium dataset.

Keywords: THEREDA; cesium chloride; sodium chloride; double salt; thermodynamic data; solubility; solid-solution

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Permalink: https://www.hzdr.de/publications/Publ-37128


The ELBE THz Sources - Tunable Coherent THz for Driving Nonequilibrium and Nonlinear Dynamics

Klopf, J. M.

Abstract

This presentation will provide an overview of the coherent THz sources and the user activities at the ELBE Radiation Source. Ideas for new types of measurements and materials to study will be discussed, followed by a look toward DALI, the concept for a new facility at HZDR for advanced accelerator-based THz sources.

Keywords: FEL; THz; IR; Ultrafast Dynamics; Nonlinear Optics; s-SNOM; DALI

Involved research facilities

Related publications

  • Invited lecture (Conferences)
    2023 HFML-FELIX User Meeting, 13.-15.06.2023, Nijmegen, Netherlands

Permalink: https://www.hzdr.de/publications/Publ-37127


Mild catalytic transfer hydrogenolysis of lignin for efficient monophenol production over lignin-coordinated N-doped ultrafine Ni nanocluster catalyst

Zhenglong, X.; Guanhua, W.; Parvez, A. M.

Abstract

Lignin hydrogenolysis into monophenols presents a promising route for lignin-based chemical and fuel production but still suffers from harsh reaction conditions (e.g. high temperature and high external H2 pressure). Herein, we report an ultrafine Ni nanocluster anchored on N-doped carbon nanosheets (Ni/LNC) for efficient catalytic transfer hydrogenolysis of poplar organosolv lignin. The catalyst was fabricated through a simple pyrolysis process of lignin‑nickel complex mixed with melamine, in which the lignin coordination greatly improved the Ni dispersion and the strong Nisingle bondN interaction inhibited the Ni nanocluster growth, resulting in the ultrafine particle size (1–2 nm). Under mild conditions (160 °C, 1 h), 22.08% of monophenol yield was obtained over the catalyst, which was significantly higher than those over the two reference catalysts (Ni/AC and Ni/LC) as well as other previously reported Ni-based catalysts. The excellent catalytic activity can be attributed to both the substantial increase in catalytic active sites and the enhancement in H transfer from methanol resulted from the electron-rich N-doped nanosheet support. Finally, magnetically recycled Ni/LNC showed excellent recycling stability. Consequently, this work presents a facile and low-cost approach for the synthesis of N-doped carbon nanosheet supported ultrafine Ni nanocluster and further demonstrates its superior applicability in lignin hydrogenolysis.

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-37125


The status and improvement opportunities towards carbon neutrality of a university campus in China: A case study on energy transition and innovation perspective

Wang, C.; Wu, T.; Parvez, A. M.

Abstract

In response to China's commitment to meet carbon peaking and carbon neutrality targets, universities are seeking to assess and minimize their greenhouse gas emissions. In this study, a new methodology based on LEAP and LCA was developed to assess the carbon footprint of a medium-sized university campus in eastern China. The emission sources consider six areas: electricity, fuel, transportation, water, waste, and consumption of other materials. The results showed that the campus emitted about 13,877 tonnes of CO2-eq in 2020. In particular, electricity consumption contributed about 77% of the total CO2-eq emissions on campus, while green cover and material recycling resulted in a negative emission of 404.4 tonnes of CO2-eq. In addition, seven common mitigation strategies were proposed to reduce the campus carbon footprint, and budgets would influence the implementation time. It was found that the seven proposed carbon reduction measures could reduce emissions by 97% in 2060, with decarbonisation of electricity being the largest contributor, leading to an emissions reduction of 64.7%. In addition, carbon offsetting is needed to achieve a carbon-neutral campus by 2060.

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-37124


Equilibrium Taylor bubble in a narrow vertical tube with constriction

Maestri, R.; Radhakrishnakumar, S.; Bürkle, F.; Ding, W.; Büttner, L.; Czarske, J.; Hampel, U.; Lecrivain, G.

Abstract

Air Taylor bubbles in a millichannel filled with water are characterized by an elongated shape, a bullet-shaped nose and a comparatively flat tail. Many experimental and numerical investigations have been performed in the past. Yet, most of them consider Taylor bubbles in a straight channel with constant cross-section. The effect of a local change in the channel geometry on both the bubble shape and the flow fields on each side of the gas-liquid interface is, however, difficult to predict. In this work, we present experimental data obtained in a vertical millichannel, where the flow is moderately obstructed by a constriction, whose ratio ranges from 10 to 36 %. \rhandrey{We find that the Taylor bubble takes an equilibrium position for downward liquid flow with 264.36 < Re < 529.67 and 264.36 < Re < 728.29 for 10.17 % and 18.06 % constriction ratios, respectively}. In this area, an empirical correlation characterizing the bubble head is provided. Other flow regimes, such as bubble breakup, co- and counter-current configurations are identified and shown in the form of a regime map. The results, besides their relevance in process engineering, exhibit high reproducibility and will serve as reference for future interface resolving two-phase flow simulations.

Keywords: Bubble dynamics; Interfacial flows; Deformation; Multiphase flows; Taylor bubbles

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37123


Roles and Structures in Institutional Research Data Management Systems

Steinmeier, L.; Rau, F.; Schaller, T.

Abstract

A dataset is considered complete if, in addition to the pure data (e.g. measured values), further information, such as origin and license for use, is also available. This requires not only the complete collection of data and metadata, but also assistance or instructions for collection and use, as well as an infrastructure for storage, publication and unique identification. Such a "value chain" is made up of various processes that should be handled by people in defined roles.

In this context, it is also necessary to provide a technical infrastructure which, on the one hand, generates a precise input mask for the user's specific case, but which, on the other hand, must direct general search queries in a targeted manner to the correct data records. And of course, this entire construct cannot be controlled without rules and documentation, and must be equipped with an adapted training offering and an intuitive user interface. The training offer is also aimed at people with roles or assigned tasks in the data management system to ensure that the roles are performed with the necessary quality by defining the necessary qualifications. A plausibility check, which takes into account the expected flexibility of the system, guarantees the consistency of the data records. In one of the highest levels of sophistication, the plausibility check is followed by a kind of self-healing mechanism that suggests a data set to the user according to the specifications or makes the user's re-intervention obsolete altogether.

In this contribution, the focus will be on the roles and on the interaction with the data management system. All necessary qualifications and tasks are assigned to the roles. The advantage of the subdivision into roles is that it remains open whether the additional tasks are covered by existing or new personnel or whether one person holds several roles. This means that the specific personnel approach can be adapted to the institution's own needs.

Keywords: research data management; FAIR data

  • Open Access Logo Poster
    4. SaxFDM-Tagung 2023, 19.10.2023, Chemnitz, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37122


Active Sites of Te-hyperdoped Silicon by Hard X-ray Photoelectron Spectroscopy

Hoesch, M.; Fedchenko, O.; Wang, M.; Schlueter, C.; Potorochin, D.; Medjanik, K.; Babenkov, S.; Ciobanu, A. S.; Winkelmann, A.; Elmers, H.-J.; Zhou, S.; Helm, M.; Schönhense, G.

Abstract

Multiple dopant configurations of Te impurities in close vicinity in silicon are investigated using photoelec- tron spectroscopy, photoelectron diffraction, and Bloch wave calculations. The samples are prepared by ion implantation followed by pulsed laser annealing. The dopant concentration is variable and high above the solubility limit of Te in silicon. The configurations in question are distinguished from isolated Te impurities by a strong chemical core level shift. While Te clusters are found to form only in very small concentrations, multi-Te configurations of type dimer or up to four Te ions surrounding a vacancy are clearly identified. For these configurations a substitutional site location of Te is found to match the data best in all cases. For isolated Te ions this matches the expectations. For multi-Te configurations the results contribute to understanding the exceptional activation of free charge carriers in hyperdoping of chalcogens in silicon.

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37121


Two-field excitation for contactless inductive flow tomography

Sieger, M.; Gudat, K.; Mitra, R.; Sonntag, S.; Eckert, S.; Wondrak, T.

Abstract

Contactless Inductive Flow Tomography (CIFT) is a flow measurement technique allowing for visualizing the global flow in electrically conducting fluids. The method is based on the precise measurement of very weak induced magnetic fields arising from the fluid motion under the influence of one or several primary excitation magnetic field(s). The simultaneous use of more than one excitation magnetic field is necessary to fully reconstruct three-dimensional liquid metal flows, yet is not trivial as the scalar values of induced magnetic field at the sensors need to be disentangled for each contribution of the excitation fields. Another approach is to multiplex the excitation fields. Here the temporal resolution of the measurement needs to be kept as high as possible. We apply two trapezoidal-shaped excitation magnetic fields with perpendicular direction to each other to a mechanically driven liquid metal flow. The consecutive application by multiplexing enables to determine the flow structure in the liquid with a temporal resolution down to 3 s with the existing equipment.

Keywords: flow measurements; inductive measurements; inverse problem; liquid metal; magnetohydrodynamics

  • Contribution to proceedings
    11th World conference on industrial process tomography (WCIPT), 06.-08.09.2023, Mexico City, Mexiko
    Proceedings of the 11th World conference on industrial process tomography
  • Lecture (Conference)
    11th World congress on industrial process tomography (WCIPT), 06.-08.09.2023, Mexico City, Mexiko

Permalink: https://www.hzdr.de/publications/Publ-37120


Parametric study on H2 evolution on porous electrodes

Rox, H.; Bashkatov, A.; Yang, X.; Mutschke, G.; Gerbeth, G.; Eckert, K.

Abstract

Alkaline water electrolysis is a mature and cost-effective technology for hydrogen production. By using wind or solar derived energy, the hydrogen produced is a promising approach to replace fossil fuels and establish a net-zero-emission-industry [1]. However, by blocking electrocatalytic sites the generated bubbles cause significant losses in terms of increased overpotential and ohmic resistance losses [2,3]. Therefore, the study of bubble dynamics on porous electrodes commonly used in industrial electrolyzers is essential to improve the overall efficiency of alkaline electrolysis.

In the present study, a novel three electrode cell is introduced to perform parametric studies of H2 evolution on porous electrodes [4]. For this purpose, electrochemical methods are combined with high-speed optical measurements to characterize the electrodes in terms of electrochemical active surface areas (ECSA), bubble size distribution and electrode coverage. The performance of the electrode can then be derived as a function of current density and applied electrolyte flow rate.

References
[1] L. Lüke and A. Zschocke, Alkaline Water Electrolysis: Efficient Bridge to CO2 -Emission-Free Economy, Chem. Ing. Tech., 92 (2020) 70–73.
[2] A. Angulo et al., Influence of Bubbles on the Energy Conversion Efficiency of Electrochemical Reactors, Joule 4 (2020) 555-579.
[3] J.R. Lake et al., Impact of Bubbles on Electrochemically Active Surface Area of Microtextured Gas-Evolving Electrodes, Langmuir 38 (2022) 3276-3283.
[4] H. Rox et al., Bubble size distribution and electrode coverage at porous nickel electrodes in a novel 3-electrode flow-through cell, Int. J. Hydrog. Energy 48 (2023) 2892-2905.

Keywords: bubble dynamics; alkaline electrolysis; porous electrodes; membraneless electrolyzer

  • Lecture (Conference)
    9th Bubble and Drop Conference, 11.-16.06.2023, Lublin, Poland

Permalink: https://www.hzdr.de/publications/Publ-37119


CFD Modeling of Phase Change during the Flashing-Induced Instability in a Natural Circulation Circuit

Liao, Y.; Lucas, D.

Abstract

Flashing-induced instability (FII) has a significant impact on the safe operation of a natural cir-culation circuit, a phenomenon frequently encountered in the cooling systems of advanced light water reactors. While one-dimensional system codes are commonly used for engineering design and safety analysis of FII, there is a strong academic interest in understanding the underlying physical mechanisms. To address this, high-resolution computational fluid dynamics (CFD) simulations serve as a valuable tool. However, the current state of CFD modeling for phase change two-phase flows, particularly high transient fluctuating flashing flows, is still in its early stages of development. In this study, we establish a CFD model that focuses on interphase heat transfer to analyze FII. By incorporating experimental data from the literature, we investigate the transient flow field and thermodynamic behavior in the riser of the GENEVA test facility. The study provides valuable insights into the non-equilibrium and interfacial transfer phenom-ena during the phase change as well as the effect of high-frequency fluctuation. Additionally, we discuss in detail the challenges associated with FII modeling and the limitations of the current model. We also provide suggestions for potential improvements in future numerical studies.

Keywords: flashing-induced instability; thermal phase change model; thermal and mechanical non-equilibrium; CFD-modelling

Permalink: https://www.hzdr.de/publications/Publ-37118


Biostimulation of Indigenous Microbes for Uranium Bioremediation in Former U Mine Water: Multidisciplinary approach assessment

Newman Portela, A.; Krawczyk-Bärsch, E.; Lopez Fernandez, M.; Bok, F.; Kassahun, A.; Drobot, B.; Steudtner, R.; Stumpf, T.; Raff, J.; Merroun, M. L.

Abstract

Characterizing the physicochemistry and microbial diversity of U mine water is a key prerequisite for understanding the biogeochemical processes occurring in these water mass and for the design of an efficient bioremediation strategy. This study has collected and analysed in reference date measurements water samples from two former U-mines (Schlema-Alberoda and Pöhla, Wismut GmbH) in East Germany. The samples from both mines are pH-circumneutral (7.3 and 6.6) and show reducing conditions (EH: +139 and –91 mV). Interestingly, the U and sulphate concentrations of Schlema-Alberoda mine water (U: 1 mg/L; SO4 2−: 335 mg/L) are 2 and 3 order of magnitude higher than those of the Pöhla samples (U: 0.01 mg/L; SO4 2−: 0.5 mg/L), respectively. U, SO4 2− and Fe seem to shape the differential microbial diversity of the water from both mines. Microbial diversity analysis revealed the distribution of bacteria with U(VI)-reducing capacity and the ability to maintain the stability of reduced U-species (e.g., Desulfurivibrio, Gallionella and Sulfuricurvum). In addition, water from the mines harbour wood-degrading fungal communities (e.g., composed of Cadophora and Acremonium) providing potential electron donors which promote the growth of U-reducing bacteria. For the design of a bioremediation strategy, we conducted a preliminary U-bioreduction experiment to screen for suitable electron donors (glycerol, vanillic acid and gluconic acid). We also observed that high levels of soluble U (initially present as Ca2UO2(CO3)3(aq) and UO2(CO3) 3 4−), Fe and SO4 2− were removed by 98, 95 and 53%, respectively from the mine water by using glycerol as electron donor. The remaining U concentrations after bioreduction meet regulatory standards for beneficial reuse of U mine water. As a whole, the results reveal the chemical factors influencing the microbial community in U mine water and may contribute to the design of bioremediation strategies based on the biostimulation of U-reducing bacteria for low U concentrations in contaminated water.

Keywords: bioremediation; bioreduction; mine water; uranium; bacterial; fungal

Permalink: https://www.hzdr.de/publications/Publ-37116


Bimetallic Pt-Hg Aerogels for Electrocatalytic Upgrading of Ethanol to Acetate

Zhang, X.; Wang, T.; Wang, C.; Hübner, R.; Eychmüller, A.; Zhan, J.; Cai, B.

Abstract

Electrochemical upgrading of ethanol to acetic acid provides a promising strategy to couple with the current hydrogen production from water electrolysis. This work reports the design of a series of bimetallic Pt-Hg aerogels, where the PtHg aerogel exhibits a 10.5-times higher mass activity than that of commercial Pt/C toward ethanol oxidation. More impressively, the PtHg aerogel demonstrates nearly 100% selectivity toward the production of acetic acid. The operando infrared spectroscopic studies and nuclear magnetic resonance analysis verify the preferable C2 pathway mechanism during the reaction. This work opens an avenue for the electrochemical synthesis of acetic acid via ethanol electrolysis.

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37115


Revisiting the selenium interactions with pyrite: from adsorption to coprecipitation

Guida, C.; Ramothe, V.; Chappaz, A.; Simonnin, P.; Rosso, K. M.; Gilbert, B.; Ding, R.-R.; Prieur, D.; Scheinost, A.; Charlet, L.

Abstract

Interactions of selenium (Se), a trace element bio-essential at low concentrations but highly toxic at high concentrations, with the most abundant mineral in the Earth's crust, namely pyrite, was investigated over a wide range of time scales. At the nanosecond scale, selenate Se(VI)O42– adsorption onto the net pyrite surface is shown by ab-initio computations to proceed via the formation of a chemical bond between an oxyanion oxygen atom and a surface Fe atom, weakening the other Se-O bonds and reducing Se atom oxidation state. At the hour-to-day scale, adsorption and coprecipitation of selenate and selenite, Se(IV)O32–, were investigated through wet chemical batch experiments at various pH values at different sulfide concentrations. Selenium removal from solution is slower and weaker for selenate than for selenite. After 24h, only 10% of selenate, against 60% for selenite (or even 100% in the presence of sulfide), is removed by the pyrite surface. Independently of its original oxidation state, adsorbed Se is completely reduced to elemental selenium via adsorption or coprecipitation, as shown by XANES spectroscopy. Our EXAFS results, compared to published data on Se-rich pyrite, show a Se to S substitution within the pyrite structure. The reductive coprecipitation mechanism of selenium with pyrite represents valuable new insights for improving our understanding of modern and ancient biogeochemical cycles involving Se. In addition, several industries can benefit from direct applications of our findings, such as water treatment, green technologies and sustainable mining.

Keywords: Selenium; Pyrite; Redox; EXAFS; XANES

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37114


No evidence for absence of solar dynamo synchronization

Stefani, F.; Beer, J.; Weier, T.

Abstract

The old question of whether the solar dynamo is synchronized by the tidal forces of the orbiting planets has recently received renewed interest, both from the viewpoint of historical data analysis and in terms of theoretical and numerical modeling. We aim to contribute to the solution of this longstanding puzzle by analyzing cosmogenic radionuclide data from the last millennium. We reconsider a recent time-series of ¹⁴C-inferred sunspot data and compare the resulting cycle minima and maxima with the corresponding conventional series down to 1610 A.D., enhanced by Schove's data before that time. We fnd that, despite recent claims to the contrary, the ¹⁴C-inferred sunspot data are well compatible with a synchronized solar dynamo, exhibiting a relatively phase stable period of 11.07 years, which points to a synchronizing role of the spring tides of the Venus-Earth-Jupiter system.

Involved research facilities

  • DRESDYN

Permalink: https://www.hzdr.de/publications/Publ-37113


A synchronized two-dimensional α–Ω model of the solar dynamo

Klevs, M.; Stefani, F.; Jouve, L.

Abstract

We consider a conventional α–Ω-dynamo model with meridional circulation that exhibits typical features of the solar dynamo, including a Hale-cycle period of around 20 years and a reasonable shape of the butterfly diagram. With regard to recent ideas of a tidal synchronization of the solar cycle, we complement this model by an additional time-periodic α-term that is localized in the tachocline region. It is shown that amplitudes of some decimeters per second are sufficient for this α-term to become capable of entraining the underlying dynamo. We argue that such amplitudes of α may indeed be realistic, since velocities in the range of m/s are reachable, e.g. for tidally excited magneto–Rossby waves.

Involved research facilities

  • DRESDYN

Permalink: https://www.hzdr.de/publications/Publ-37112


Machine learning the electronic structure of matter across temperatures

Fiedler, L.; Modine, N. A.; Miller, K. D.; Cangi, A.

Abstract

We introduce machine learning (ML) models that predict the electronic structure of materials across a wide temperature range. Our models employ neural networks and are trained on density functional theory (DFT) data. Unlike other ML models that use DFT data, our models directly predict the local density of states (LDOS) of the electronic structure. This provides several advantages, including access to multiple observables such as the electronic density and electronic total free energy. Moreover, our models account for both the electronic and ionic temperatures independently, making them ideal for applications like laser-heating of matter. We validate the efficacy of our LDOS-based models on a metallic test system. They accurately capture energetic effects induced by variations in ionic and electronic temperatures over a broad temperature range, even when trained on a subset of these temperatures. These findings open up exciting opportunities for investigating the electronic structure of materials under both ambient and extreme conditions.

Related publications

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Permalink: https://www.hzdr.de/publications/Publ-37111


Keeping the HELIPORT Code Base Maintainable: Our Tools and Approaches

Pape, D.; Voigt, M.; Knodel, O.

Abstract

In this talk, different approaches to keeping the HELIPORT code base maintainable will be presented. The talk will discuss both the tools used to automate various aspects of development and operation of HELIPORT, as well as how certain aspects of development are approached and how the choice of libraries and tooling helps these aspects.

Keywords: Research Software Engineering; Maintainability; Continuous Integration; Metadata

  • Open Access Logo Lecture (others)
    HELIPORT Workshop 2023, 12.-14.06.2023, Dresden, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-37110


Machine Protection System Upgrade for a new Timing System at ELBE

Justus, M.; Kuntzsch, M.; Schwarz, A.; Zenker, K.; Oven, Z.; Perusko, L.; Krmpotic, L.; Legat, U.; Rojec, U.

Abstract

Running a C.W. electron accelerator as a user facility for more than two decades necessitates upgrades or even complete redesign of subsystems at some point. At ELBE, the outdated timing system needed a replacement due to obsolete components and functional limitations. Starting in 2019, with Cosylab as contractor and using hardware by Micro Research Finland, the new timing system has been developed and tested and is about to become operational. Besides the ability to generate a broader variety of beam patterns from single pulse mode to 26 MHz C.W. beams for the two electron sources, one of the benefits of the new system is improved machine safety. The ELBE control systems is mainly based on PLCs and industrial SCADA tools. This contribution depicts how the timing system implementation to the existing machine entailed extensions and modifications of the ELBE machine protection system, i.e. a new core MPS PLC, and how they are being realized.

Keywords: ELBE; MPS; Machine Protection System; Timing System; MRF; Control System

Involved research facilities

Related publications

  • Poster
    ICALEPCS 2023, 09.-13.10.2023, Cape Town, South Africa
  • Open Access Logo Contribution to proceedings
    ICALEPCS 2023 - 19th International Conference on Accelerator and Large Experimental Physics Control Systems, 09.-13.10.2023, Cape Town, South Africa
    Proceedings of the 19th International Conference on Accelerator and Large Experimental Physics Control Systems, Geneva, Switzerland: JACoW Publishing, 978-3-95450-238-7, 542-546
    DOI: 10.18429/JACoW-ICALEPCS2023-TUPDP021
    ISSN: 2226-0358

Permalink: https://www.hzdr.de/publications/Publ-37109


SCADA Support & Maintenance für den ELBE Beschleuniger

Justus, M.; Steinbrück, R.

Abstract

Für den Betrieb des Elektronen-Linearbeschleunigers am ELBE - Zentrum für Hochleistungsstrahlenquellen arbeiten wir im Bereich SCADA-System seit 2019 mit Kontron AIS GmbH im Rahmen eines Dienstleistungsvertrags zusammen. Wir stellen in der Präsentation den Beschleuniger vor, beschreiben die einzelnen Support- und Projektthemen und die damit verbundenen Vorteile für Betriebssicherheit und Nutzerfreundlichkeit und Wieterentwicklung unseres WinCC Leitsystems.

Keywords: ELBE; SCADA; WinCC

Involved research facilities

Related publications

  • Invited lecture (Conferences)
    Kontron AIS - 22. User Conference 2023, 15.06.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37108


Dry release of MEMS origami using thin Al2O3 films for facet-based device integration

Zhang, J.; Reif, J.; Strobel, C.; Chava, P.; Erbe, A.; Voigt, A.; Mikolajick, T.; Kirchner, R.

Abstract

In recent years, more and more research was conducted to explore smaller and smaller systems that become similar to an
actual micro/nano-robot. The major roadblock regarding their real world implementation is the highly restricted available
volume. In this paper, we introduce folding – hence an origami technology using Al2O3 as building material, which is
compatible with current Si technology. High quality 50 nm thin Al2O3 film is grown by atomic layer desposition, patterned,
thinned and then released from the Si subtrate using SF6 plasma etching. The realized free standing Al2O3 structure would
fold itself at predefined regions due to the stress in the as deposited films. We believe such technology could offer a new
possibility to tackle the problem of efficiently using the volume. Al2O3 could act as both the structural origami material and
the functional gate dielectric material for electronics. This approach enables the feasibility of patterning devices and circuits
on every Al2O3 facet of a 3D object, while the inside volume of this object is still available for 3D bulk device components.
We demonstrate the optimized etching process as well as an emperical improvement of the folding hinges and of the overall
structural stability.

Keywords: 3D; Dielectric; EMS/NEMS; Etching; Integration; Origami; Self assembly

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37107


Interactive workflows and data provenance with HELIPORT

Kelling, J.; Pape, D.; Starke, S.; Lokamani, M.; Knodel, O.

Abstract

Data processing or analysis workflows are generally understood as processes running without any user intervention where usually only a small set of parameters being provided upon workflow submission, adjustment of which is also limited by low turnaround rates of workflow runs due to scheduling alone. Many types of experimental data analyses require manual experimentation with parameters to succeed, necessitating interactivity and fast iteration. In this talk we present examples of interactive workflow applications at HZDR, from data analysis and simulation; discuss challenges arising from differences to completely automated workflows and lay-out the related data-provenance and project-resource management features we envision for the HELIPORT workflow platform.

Keywords: workflows; data management; data provenance; project management

  • Open Access Logo Lecture (others)
    HELIPORT Workshop 2023, 12.-14.06.2023, Dresden, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-37106


Unraveling the Hydration Dynamics of Biomolecular Condensates

Raj, M.; Jahnel, M.; Adams, E.

Abstract

Compartmentalisation in a cell occurs by lipid membrane bound organelles or membrane-less organelles (MLOs). MLOs are dynamic liquid-like condensates inside the cell constituted of various biomolecules formed by liquid-liquid phase separation (LLPS). In LLPS, a biomolecule in an aqueous solution de-mixes from a single well-mixed phase to form two phases – a concentrated phase and a dilute phase. It creates a local concentration hotspot for the biomolecule, leading to enhancement of associated biological functions.
Creating two phases from a single well-mixed aqueous phase involves significant restructuring of the hydration water around the biomolecule. These dynamics are expected to play a crucial role in forming two coexisting phases in the same medium. However, the solvent's role in forming biomolecular condensates remains a relatively unexplored territory.
Recent pioneering work from our group has uncovered the critical role of solvent in the phase separation of RNA binding proteins (RBPs) and how differences in local hydration behaviour leads to phase separation. Following up on our previous work, we study how the alteration of hydration dynamics of different RBPs leads to their phase separation and how protein level modifications in the RBP modulate these dynamics.

  • Poster
    Bunsentagung, 05.-07.06.2023, Berlin, Germany

Permalink: https://www.hzdr.de/publications/Publ-37105


Insights into uranium sequestration by coal fly-ash-derived zeolites: Understanding via wet-chemistry, and advanced spectroscopies

Sobczyk, M.; Dinh, N.; Marzec, M.; Bazarkina, E.; Kvashnina, K.; Cwanek, A.; Lokas, E.; Bajda, T.

Abstract

The operation of nuclear power plants requires a supply of nuclear fuel where uranium plays a substantial role as a primary fissile material. Its extraction from U-bearing minerals and handling may cause a leakage of heavily toxic radioactive pollution, which ends up in water bodies and soil. Therefore, tackling U-contaminated water is crucial to preserve water integrity and quality. Zeolites are known as profound ion exchangers with great affinity towards cationic species present in polluted waters. Various zeolite synthesis routes have made this group of aluminosilicates even more promising to be applied as water purification materials. Here, the synthetic gismondite, faujasite, and Linde type-A zeolites from coal fly-ash were synthesized via tailored, coupled fusion-hydrothermal method and applied to remove aqueous uranium (primarily as 238U) under varying pH, time (sorption kinetics), and initial U concentrations (sorption isotherms). The maximum U uptake was observed for Na–P1 (GIS) zeolite, which equals 48.72 mg U/g, the highest reported value on maximum U adsorption capacity for zeolitic materials. The U adsorption kinetics showed that equilibrium is reached after approximately 3 h of adsorption and that the removal process follows a Freundlich isothermal model for all zeolites, thus preferential adsorption onto heterogeneous surfaces. Advanced spectroscopic studies, including laboratory-scale X-ray Photoelectron Spectroscopy with synchrotron light X-ray Absorption Near Edge Structure in High Energy Resolution Fluorescence Detection mode, revealed that at acidic pH, predominantly an ion exchange between Na+ ions with hexavalent uranyl species takes place. In contrast, in the neutral pH region, the U is immobilized via precipitation in the form of μm-scale mineral aggregates of Na-schoepite: Na(UO2)4O2(OH)55↓. The outcomes of the research study has demonstrated that synthetic zeolites, obtained from industrial by-products such as coal fly-ash, can be successfully valorized to efficient U adsorbents while unveiling the insights to understand the zeolites/U interactions at the nanoscale level.

Keywords: radioisotopes; synchrotron radiation; ion exchange; precipitation; wastewater treatment

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-37104


Supplementary file: Intracellular biocompatible hexagonal boron nitride quantum emitters as single-photon sources and barcodes

Kavčič, A.; Podlipec, R.; Vella, D.; Humar, M.

Abstract

Supplementary information

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Permalink: https://www.hzdr.de/publications/Publ-37102


AC impedance spectroscopy to characterize the dielectric material properties in concrete during decommissioning of nuclear power plants

Nurjahan, T.; Schleicher, E.; Hampel, U.

Abstract

Electrical impedance spectroscopy (EIS) is a powerful technique to study material properties, e.g., it is highly sensitive to the moisture content of inhomogeneous cementitious materials. This study contributes to the in-situ measurement of the moisture content (MC) in concrete during the decommissioning of nuclear power plants. Thus, a comprehensive investigation of dielectric material properties of concrete has been performed experimentally and over a 10 Hz to 10MHz range of frequencies through alternating current (AC) impedance spectroscopy.

Keywords: Impedance spectroscopy; Dielectric material properties; Concrete; Moisture content

Involved research facilities

  • TOPFLOW Facility
  • Contribution to proceedings
    IEEE Conference on Electrical Insulation and Dielectric Phenomena, 15.-19.10.2023, East Rutherford, NJ, USA
    IEEE, 1-4
    DOI: 10.1109/CEIDP51414.2023.10410454

Permalink: https://www.hzdr.de/publications/Publ-37099


Alloyed RexMo1 − xS2 Nanoflakes with Enlarged Interlayer Distances for Hydrogen Evolution

Li, J.; Hübner, R.; Deconinck, M.; Bora, A.; Göbel, M.; Schwarz, D.; Chen, G.; Wang, G.; Yang, S. A.; Vaynzof, Y.; Lesnyak, V.

Abstract

Molybdenum sulfide (MoS2) has attracted significant attention due to its great potential as a low-cost and efficient catalyst for the hydrogen evolution reaction. Developing a facile, easily upscalable, and inexpensive approach to produce catalytically active nanostructured MoS2 with a high yield would significantly advance its practical application. Colloidal synthesis offers several advantages over other preparation techniques to overcome the low reaction yield of exfoliation and drawbacks of expensive equipment and processes used in chemical vapor deposition. In this work, we report an efficient synthesis of alloyed RexMo1−xS2 nanoflakes with an enlarged interlayer distance, among which the composition Re0.55Mo0.45S2 exhibits excellent catalytic performance with overpotentials as low as 79 mV at 10 mA/cm2 and a small Tafel slope of 42 mV/dec. Density functional theory calculations prove that enlarging the distance between layers in the RexMo1−xS2 alloy can greatly improve its catalytic performance due to a significantly reduced free energy of hydrogen adsorption. The developed approach paves the way to design advanced transition metal dichalcogenide-based catalysts for hydrogen evolution and to promote their large-scale practical application.

Keywords: RexMo1−xS2 alloys; enlarged interlayer distance; nanoflakes; colloidal synthesis; hydrogen evolution

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-37098


Versatile, compact chirped pulse amplifier pump system for ultrafast optical parametric amplifiers

Zobus, Y.; Brabetz, C.; Löser, M.; Albach, D.; Siebold, M.; Bagnoud, V.

Abstract

We report on the development of a pump system for ultrafast optical parametric amplifiers (uOPA) as an upgrade for the existing uOPA at the Petawatt High Energy Laser for heavy Ion eXperiments (PHELIX) and the new Petawatt ENergy-Efficient Laser for Optical Plasma Experiments (PEnELOPE). The system consists of a two-stage chirped pulse amplifier, centered around a high energy Yb:YAG regenerative amplifier that delivers 108 mJ uncompressed output energy, resulting in 92 mJ at 1030 nm after compression, pulse durations of 1.4 ps, a high beam quality of Mx/y2 = 1.02 / 1.16 and a relative energy stability of 0.35 %. A second harmonic generation (SHG) efficiency of up to 70 % is achievable and a maximum pulse energy of 43 mJ at 515 nm has been obtained, which is only limited by the damage threshold of the SHG crystal. A self-phase modulation stage makes this system a widely applicable, self-seedable pump module for uOPA without placing strong requirements on its seed oscillator.

Keywords: High power lasers; Laser damage; Laser plasmas; Optical amplifiers; Laser systems; hase matching

Permalink: https://www.hzdr.de/publications/Publ-37097


Electronic density response of warm dense hydrogen on the nanoscale

Dornheim, T.; Böhme, M.; Moldabekov, Z.; Vorberger, J.

Abstract

The properties of hydrogen at warm dense matter (WDM) conditions are of high importance for the understanding of astrophysical objects and technological applications such as inertial confinement fusion. In this work, we present extensive new \emph{ab initio} path integral Monte Carlo (PIMC) results for the electronic properties in the Coulomb potential of a fixed ionic configuration. This gives us new insights into the complex interplay between the electronic localization around the protons with their density response to an external harmonic perturbation. We find qualitative agreement between our simulation data and a heuristic model based on the assumption of a local uniform electron gas model, but important trends are not captured by this simplification. In addition to being interesting in their own right, we are convinced that our results will be of high value for future projects, such as the rigorous benchmarking of approximate theories for the simulation of WDM, most notably density functional theory.

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Permalink: https://www.hzdr.de/publications/Publ-37096


Data publication: Universal radiation tolerant semiconductor

Bektas, U.; Chekhonin, P.; Klingner, N.; Hlawacek, G.

Abstract

EBSD data and irradiation parameters

Keywords: ion irradiation; Ga2O3; phase transformation; Polymorph; EBSD

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Permalink: https://www.hzdr.de/publications/Publ-37095


Antibacterial effect of nanoparticles

Schuba, S.; Zhao, X.; Illing, R.; Schütt, J.; Faßbender, J.; Baraban, L.; Makarov, D.

Abstract

Over the last century, antibiotics against bacterial infections have led
to increased life expectancy and quality of people worldwide. Yet the
WHO has brought attention to the increasing resistance development
of bacterial pathogens against antibiotics - many bacteria are already
multi-resistant. In the search for alternatives to classical antibiotics,
nanotechnology and nanoparticles (NP) are moving into the focus of
scientific research. Particular attention is paid to the Nano-silver (Ag-
NP), which has experienced an immense upswing in recent years and is
used in many medical products such as wound dressings or consumer
products. However, are Ag-NPs safe for health and the environment? To
tackle this challenge, conventional methods have been used to explore
nanoparticle resistance. Conversely, these methods have proven to be
limited in terms of labor, cost, and statistical power. In our work,
we intend to overcome these barriers by developing a droplet-based
microfluidic analytical platform as a tool to elucidate the impact and
biological influence of nanoparticles on living microorganisms with high
statistical evaluation and detection efficiency. This method allows the
separation of bacteria into single droplets, the generation of individual
bioreactors, and the screening of bacterial metabolism in the
presence of Ag-NP.

Keywords: E.coli; Silver; Nanoparticles; Resistence; droplet-based microfluidics

Involved research facilities

Related publications

  • Invited lecture (Conferences)
    BioNanoSens Summer School, 05.-07.06.2023, HZDR, Germany

Permalink: https://www.hzdr.de/publications/Publ-37094


Optical analytics of nanoparticles in liquids

Schuba, S.; Zhao, X.; Illing, R.; Schütt, J.; Faßbender, J.; Baraban, L.; Makarov, D.

Abstract

Over the last century, antibiotics against bacterial infections have led
to increased life expectancy and quality of people worldwide. Yet the
WHO has brought attention to the increasing resistance development
of bacterial pathogens against antibiotics - many bacteria are already
multi-resistant. In the search for alternatives to classical antibiotics,
nanotechnology and nanoparticles (NP) are moving into the focus of
scientific research. Particular attention is paid to the Nano-silver (Ag-
NP), which has experienced an immense upswing in recent years and is
used in many medical products such as wound dressings or consumer
products. However, are Ag-NPs safe for health and environment? To
tackle this challenge, conventional methods have been used to explore
nanoparticle resistance. Conversely, these methods have proven to be
limited in terms of labor, cost, and statistical power. In our work,
we intend to overcome these barriers by developing a droplet-based
microfluidic analytical platform as a tool to elucidate the impact and
biological influence of nanoparticles on living microorganisms with high
statistical evaluation and detection efficiency. This method allows the
separation of bacteria into single droplets, the generation of individual
bioreactors, and the screening of bacterial metabolism in the
presence of Ag-NP.

Keywords: E.coli; Nanoparticles; droblet-based microfluidics; Silver; Resistance

Involved research facilities

Related publications

  • Lecture (others)
    Priority Training School, Recent Trends in Microplastic research, 24.05.2023, HZDR, Germany

Permalink: https://www.hzdr.de/publications/Publ-37093


Evaluation of nanoparticle resistance development of microorganisms

Schuba, S.; Schütt, J.; Illing, R.; Faßbender, J.; Makarov, D.

Abstract

In this presentation we discuss our achievements on the use of fluidic activities for the detection of impact of nanoparticles on microorganisms.

Keywords: E.coli; Bacteria; Ag nanoparticles; Droplets; Fluidics

Involved research facilities

Related publications

  • Poster
    HZDR DocSeminar 2022, Wrocław, Poland, 19.-21.10.2022, Wrocław, Poland

Permalink: https://www.hzdr.de/publications/Publ-37092


TiO2 phase engineering by millisecond range annealing for highly efficient photocatalysis

Prucnal, S.; Gago, R.; Gonzales Calatayud, D.; Rebohle, L.; Oskar Liedke, M.; Butterling, M.; Wagner, A.; Helm, M.; Zhou, S.

Abstract

Air pollution and the energy crisis are the two main driving forces behind the development of alternative, environmentally friendly methods of energy production. Photoactive materials can be used both to clean the air and to produce green hydrogen for clean energy. Transition metal oxides are one of the most considered materials for high-performance photocatalysis. In this work, we investigate the effect of millisecond flash lamp annealing (FLA) of TiO2 on the degradation of methyl blue (MB) and methyl orange (MO). To reduce the energy consumption of the TiO2 deposition process, the layers were made using magnetron sputtering at room temperature, followed by millisecond FLA. By controlling the flash energy input, we can tune the phase formation of TiO2 films from pure anatase to mixed anatase/rutile phases. Scanning electron microscopy, positron annihilation spectroscopy, photoluminescence and X-ray diffraction studies show that the crystal size and film quality increase with increasing annealing temperature. Photocatalytic experiments demonstrate that FLA-treated TiO2 films are active in degrading both MB and MO. This makes them attractive not only for the production of green hydrogen, but also for the purification of water from medical contaminants.

Keywords: TiO2; flash lamp annealing; photocatalysis; methyl blue

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37091


Millijoule Ultrafast Optical Parametric Amplification as Replacement for High-Gain Regenerative Amplifiers

Zobus, Y.; Brabetz, C.; Hornung, J.; Ohland, J.; Reemts, D.; Zou, J.-P.; Löser, M.; Albach, D.; Schramm, U.; Bagnoud, V.

Abstract

We report on the development of an ultrafast optical parametric amplifier (uOPA) front-end for the Petawatt High Energy Laser for heavy Ion eXperiments (PHELIX) and the Petawatt ENergy-Efficient Laser for Optical Plasma Experiments (PE NELOPE). This front-end delivers broadband and stable amplification up to 1 mJ per pulse while maintaining a high beam quality. Its implementation at PHELIX allowed to bypass a front-end amplifier that was known to be a source of pre-pulses. With the bypass, an amplified spontaneous emission (ASE) contrast of 4.9·10−13 and a pre-pulse c ntrast
of 6.2·10−11 could be realized. Due to its high stability, high beam quality and its versatile pump amplifier, the system
offers an alternative for high-gain regenerative amplifiers in the front-end of vario

Keywords: ultrafast optical parametric amplification; temporal laser contrast

Permalink: https://www.hzdr.de/publications/Publ-37090


Energy storage in liquid metals and fused salts

Weier, T.; Ding, W.; Duczek, C.; Horstmann, G. M.; Landgraf, S.; Lee, J.; Nash, W.; Monrrabal Marquez, G.; Sarma, M.; Weber, N.

Abstract

Stationary electric energy storage systems can help balance temporal differences
in electricity supply and demand. With the increasing use of volatile electricity
sources, this task is becoming more important. Liquid metal and molten salt
batteries are high-temperature storage devices and one option for stationary
storage. They are based on the stable density stratification of a liquid alkali
metal, a fused salt and a molten heavy metal. Mediated by the high operating
temperature, which must be above the melting temperatures of the individual
phases, interfacial reactions are rapid and transport processes are fast. High
current and power densities can thus be reached. The completely liquid cell
interior enables conceptually simple scalability at the cell level, which suggests
favorable energy-related investment costs. Electrode and electrolyte layers possess
thicknesses in the millimeter range and consist either of pure metals or a small
number of components. Both properties will facilitate recycling considerably.
The battery concept enables the use of abundant and cost effective active
material combinations like Na-Zn. In contrast to most other battery systems,
fluid mechanical processes, which are closely coupled to charge transport and
transfer, are of relatively high importance. The talk will present selected physical
phenomena in liquid metal batteries as well as discuss their possible role in a
future energy system.

Keywords: liquid metal battery; ZEBRA; membrane free; SOLSTICE

  • Lecture (Conference)
    Helmholtz Energy Conference 2023, 12.-13.06.2023, Koblenz, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37089


Dosimetry and Activation Calculations for Optimal Decommissioning Planning of NPPs

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

Abstract

In April 2023, all German nuclear power plants (NPPs) will have been shut down. The final shutdown is followed by a post-operational phase in which measures can be carried out to prepare for the NPPs dismantling and decommissioning. One of the essential tasks in planning and preparing an NPP for decommissioning is to obtain precise knowledge of the activation levels in its reactor pressure vessel (RPV), the biological shielding, and other internal components. In that regard, a method based on the combined use of two Monte Carlo codes, MCNP6 and FLUKA2021, was developed to serve as a non-destructive tool for evaluating the activation in an NPP. The methodology is demonstrated through the activation calculations of selected components of a German pressurized water reactor (PWR), Germany's most common NPP type. In the first step, the MCNP6 code was used to calculate the neutron fluence rate characteristics in the studied component using a detailed 3D model of a German PWR. The neutron source defined in the model was based on burn-up calculations provided by the operator. The neutron fluence rate prediction capability of the MCNP6 model was validated using neutron fluence monitors placed inside two German PWRs. The validation studies showed that the MCNP6 model and neutron sources are reliable and suitable for evaluating the neutron radiation field in the reactor for the ensuing activation calculations. In the second step, the FLUKA2021 code was used to calculate the specific activity in the studied component using a 3D exact model of the component and complex source terms built based on the neutron fluence rate parameters computed using the MCNP6 code. The results of the calculations were obtained with great accuracy and can be used as guidelines for optimal planning of the discharged reactor components' disposal and storage.

Keywords: Decommissioning; Monte Carlo; Dosimetry; Activation; PWR

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

Permalink: https://www.hzdr.de/publications/Publ-37088


Strong anharmonicity in the vibrational spectra of Cu+(H2O)(H2)2

Gouatieu Dongmo, E.; Haque, S.; Jin, J.; Wulf, T.; Asmis, K. R.; Heine, T.

Abstract

For some years now, research on adsorptive separation of hydrogen isotopes such as deuterium (D) and
tritium (T) has been evolving with a view toward nuclear fusion. Experimental and theoretical investigations
show that H2 strongly binds to undercoordinated Cu+ sites and more strongly when one H2O ligand is added
to Cu+.[1] To understand the vibrational behavior that drives the hydrogen isotopologue selectivity of
Cu+(H2O)(H2)2 formation, harmonic and anharmonic vibrational spectra have been computed and compared
to infrared photodissociation (IRPD) spectroscopy results from the gas phase. Our calculations show that
geometries and harmonic frequencies at the MP2/def2-TZVPP level match CCSD(T)/aug-cc-pVTZ ones
very closely. Scaling the harmonic frequencies by a factor of 0.95 [2] improves the agreement with the
available experimental data, but fails to produce the combination bands. By contrast, anharmonic VPT2
calculations at the MP2/def2-TZVPP level not only predict these bands but they also reproduce the
experimental frequencies very well. In addition to that, we found a similar structure for Cu+(H2O)(H2)2 as a
previous study[1]: a planar arrangement with C2v symmetry (Figure 1) but with a significantly shorter
Cu+–H2 bond length (1.62 Å vs 1.71 Å). Finally, the obtained results show that CCSD(T) calculations are
not required and VPT2 frequencies at the MP2/def2-TZVPP level are identified as a particularly good
compromise for future modeling of the vibrational properties driving isotopologue-selective H2 adsorption
at undercoordinated Cu+ sites.

Reference
[1] Paul R. Kemper et al., J. Am. Chem. Soc., 120:51,13494-13502 (1998)
[2] N. Heine et al., J. Phys. Chem. Lett., 6(12):2298-2304 (2015)

  • Open Access Logo Poster
    58th Symposium on Theoretical Chemistry, 15.-18.09.2022, Heidelberg, Germany

Permalink: https://www.hzdr.de/publications/Publ-37087


Numerische Auslegung eines thermischen Festkörperspeichers

Nieke, L.; Unger, S.

Abstract

Im Rahmen dieser Projektarbeit wurde ein Hochtemperaturwärmespeicher ausgelegt.
Beginnend mit einer überblicksartigen Darstellung der Anwendung und Einteilung von Wärmespeichern wird der Stand der Technik anhand ausgewählter Forschungsprojekte zu Festkörperwärmespeichern vorgestellt. Darauf aufbauend werden im folgenden Kapitel 3 das angewendete Konzept der Auslegung sowie die zugrundeliegenden Stoffeigenschaften des Festkörpermaterials und des eingesetzten Fluides erläutert.
In Kapitel 4 wird die überschlägige Auslegung anhand einer analytischen Berechnung vorge-stellt. Besonderes Augenmerk liegt dabei auf der Berechnung der Wärmestrahlung des eingesetzten Fluides CO2. Es ist festzustellen, dass bei Berücksichtigung der Wärmestrahlung der Aufheizvorgang bei Aufheizung von 400 °C auf (gemittelt) 900 °C für einen 20 m langen Speicher knapp 18 % schneller verläuft, als bei gleichen Bedingungen ohne Berücksichtigung der Wärmestrahlung. Bei einem 4 m langen Speicher verläuft der Aufheizvorgang sogar über 45 % schneller, da hier aufgrund der geringeren Länge die Exergieverluste bei Vernachlässigung der Wärmestrahlung deutlich höher sind.
Die präzise Berechnung des Aufheizvorgangs anhand einer numerischen Simulation wird in Kapitel 5 beschrieben. Auch hier liegt das besondere Augenmerk auf der Berechnung der Wärmestrahlung. Dafür werden verschiedene in dem Programm ANSYS CFX zur Verfügung stehende Berechnungsmethoden für Wärmestrahlung untersucht und die Discrete-Transfer-Methode als für diesen Fall geeignet ermittelt. Darüber hinaus stellt bei der Modellierung der großen Geometrie (Länge von 20 m), bei Berücksichtigung der Wärmestrahlung und einem feinen Netz der entstehende Berechnungsaufwand eine große Herausforderung dar. Durch die Betrachtung eines kürzeren Speichers mit einer Länge von 4 m kann der Berechnungsaufwand verringert und damit die Qualität der Berechnungsergebnisse erhöht werden. Anhand der numerischen Modellierung konnte die analytische Berechnung annäherungsweise bestätigt werden.
Zur Untersuchung des Einflusses des Designs auf das Aufheizverhalten wurde anhand der analytischen Berechnung eine Reihe von verschiedenen Querschnittsvarianten untersucht. Es
7 Zusammenfassung und Ausblick
67
zeigt sich, dass bei Beachten der volumetrischen Energiedichte des Speichers und des nötigen Volumenstroms je gespeicherter Energie, möglichst kleine Dimensionen verwendet werden sollten. Allerdings ist hierbei die Frage der mechanischen Festigkeit durch thermische Spannungen, insbesondere im Dauerbetrieb zu beachten, wodurch ein nicht bestimmbarer Grenzwert für die minimale Größe der Strukturen definiert wird. Zugleich wurde mit der numerischen Simulation der Effekt des Wärmewiderstandes im Festkörper untersucht, wobei für den untersuchten Wandstärkenbereich keine signifikanten Temperaturgradienten durch die Modellierung ermittelt werden konnten.
Ausblickend können neben der Untersuchung des Einflusses der Querschnittsabmessungen zusätzliche andere Betriebsparameter, wie z. B. die Strömungsgeschwindigkeit oder der Systemdruck, untersucht werden.
Darüber hinaus wäre die Modellierung eines gesamten Wärmespeichersystems mit Kreis-laufführung des Fluides sinnvoll, um die in der Modellierung entstehenden Exergieverluste ausschließen zu können. Damit einhergehend wäre für die Kreislaufführung die über die Zeit aufnehmbaren (elektrischen) Energieströme zum Aufheizen des Fluides von der Austrittstemperatur aus dem Speicher auf 1000 °C oder der nötige Volumenstrom zum Erreichen einer geforderten (elektrischen) Aufheizleistung nötig.
Weiterhin sollten durch eine experimentelle Untersuchung die Stoffeigenschaften des Festkörpermaterials verifiziert werden, da insbesondere die Wärmeleitfähigkeit der Keramik nur in einem sehr großen Bereich von 3,5 W/(m K) bis 35 W/(m K) gegeben ist. Für die Berechnung wurde auf der sicheren Seite liegend zwar der untere Wert dieses Bereiches verwendet, allerdings sind in anderen Literaturstellen [9] für Keramikmaterialen Werte in einer Größenordnung des oberen Wertebereichs angegeben (siehe Tabelle 2-1). Zusätzlich kann durch eine experimentelle Untersuchung die Problematik der mechanischen Festigkeit geprüft werden.

Involved research facilities

  • TOPFLOW Facility
  • Study thesis
    TU Dresden, 2023
    Mentor: Sebastian Unger
    119 Seiten

Permalink: https://www.hzdr.de/publications/Publ-37086


A novel ACE2 decoy for both neutralization of SARS-CoV-2 variants and killing of infected cells

Kegler, A.; Drewitz, L.; Arndt, C.; Daglar, C.; Rodrigues Loureiro, L. R.; Mitwasi, N.; Neuber, C.; González Soto, K. E.; Bartsch, T.; Baraban, L.; Ziehr, H.; Heine, M.; Nieter, A.; Moreira-Soto, A.; Kühne, A.; Drexler, J. F.; Seliger, B.; Laube, M.; Máthé, D.; Pályi, B.; Hajdrik, P.; Forgách, L.; Kis, Z.; Szigeti, K.; Bergmann, R.; Feldmann, A.; Bachmann, M.

Abstract

The COVID-19 pandemic caused by SARS-CoV-2 led to millions of infections and deaths worldwide. As this virus evolves rapidly, there is a high need for treatment options, which can win the race against new emerging variants of concern. Here, we describe a novel immunotherapeutic drug based on the SARS-CoV-2 entry receptor ACE2 and provide experimental evidence that it cannot only be used for (i) neutralization of SARS-CoV-2 in vitro and in SARS-CoV-2 infected animal models, but also for (ii) clearance of virus infected cells. For the latter purpose, we equipped the ACE2 decoy with an epitope tag. Thereby, we converted it to an adapter molecule which we successfully applied in the modular platforms UniMAB and UniCAR for retargeting of either unmodified or universal chimeric antigen receptor modified immune effector cells. Our results pave the way for a clinical application of this novel ACE2 decoy, which will clearly improve COVID-19 treatment.

Keywords: SARS-CoV-2; COVID-19; ACE2 decoy; T cell based immunotherapy; bispecific antibody; adapter CAR platform

Involved research facilities

  • ZRT

Permalink: https://www.hzdr.de/publications/Publ-37085


Self-folding of two-dimensional thin templates into pyramidal micro-structures by a liquid drop - a numerical model

Lecrivain, G.
ContactPerson: Lecrivain, Gregory

Abstract

Source files and selected raw data related to the manuscript "Self-folding of two-dimensional thin templates into pyramidal micro-structures by a liquid drop - a numerical model" by Gregory Lecrivain, Helmholtz-Zentrum Dresden-Rossendorf, Germany, 2024.

1) folder "manuscript",
This folder contains all text documents related to manuscript. Text and final figures are found in the directory.

2) folder "scripts"
This folder contains python and bash scripts used to post-process the raw data and prepare the figures. You will need to install some python3 libraries. Use the following command: pip install pyquaternion matplotlib scipy intersect.

3) folder "figures"
This folder contain information on how to run the simulations related to the figure. More information can be found in the README text file located in each figure/figX subfolder, where X the figure number in the manuscript.

4) folder "src"
This folder contains the all c++ files related to the source code.

4.1)
Prior to compiling, you should have gcc(7.3.0), openmpi(2.1.2), make(4.3), cmake(3.20.2), python(3.8.0), blas(3.8.0), lapack(3.8.0), boost(1.78.0), and git(2.30.1) available on your machine. The version number in the parenthesis corresponds to the one I used on the local HPC available at my institution. In my case, I type "module load gcc/7.3.0 openmpi/2.1.2 make/4.3 cmake/3.20.2 python/3.8.0 blas/3.8.0 lapack/3.8.0 boost/1.78.0 git/2.30.1".

4.2)
To compile the libraries, open a terminal, cd to the src directory and type "make libs". All outputs will placed in the folder $HOME/local. The libraries' tarballs needed to compile the code are placed in the Libs directory.

4.3)
I have manually installed paraview 5.9.1. pvpython is used to export txt data (hinge, drop and three-phase contact line) to vtk format.

4.4)
Open your ~/.bashrc file and add the following lines.
export IGL_NUM_THREADS=1
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$HOME/local/libconfig-1.7.3/lib
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$HOME/local/gmp-6.2.1/lib
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$HOME/local/mpfr-4.1.0/lib
export PATH=$PATH:$HOME/microorigami/src #(or whereever, your chosen parent directory is)
export PATH=$PATH:$HOME/microorigami/scripts #(or whereever, your chosen parent directory is)
export PATH=$PATH:$HOME/microorigami/paraview/bin #(or whatever path you used)

4.5)
open a new terminal, cd to the src directory and type "make check_library_path". The terminal should return
"library path to libconfig is correct"
"library path to gmp is correct"
"library path to mpfr is correct"
If that is the case, i.e. the paths are correctly set. To compile, type "make main post". Alternatively, one can speed up the installation by typing "make -j 4 main post", where 4 is the number of cpus I use.

4.6)
Help is available in each header file (.h) in the form of doxygen comments. Type "make doxy". The folder html will appear under src.

4.7)
Type "make clean" to clean the src folder

5) folders "caX_sideY_ecZ.zip"
The zip files contains the raw data related to Figure 10. Here, X = 70 is the contact angle, Y = 5 the number of side panels and Z = 0.8, 1.6 and 2.4 the elasto-capillary number. After data extraction, three folders will be created, namely wd/ca70/side5/ec0.8, wd/ca70/side5/ec1.6 and wd/ca70/side5/ec2.4, where wd is your working directory. To convert the data into human-readable format (txt, vtk, stl,...) type "source Utils.sh; ExportScript --verbose --submit" in the working directory wd on the hpc. The bash function ExportScript is located in "scripts/Utils.sh". All other raw data can be obtained by following the commands in the README text file located in each figX folder, with X=1,2,...,13. With Paraview, one is able to visualize the self-folding by loading the stl files.

Keywords: Micro-origami simulation; Drop encapsulation; Self-folding; Fluid-structure interaction

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Permalink: https://www.hzdr.de/publications/Publ-37084


Tellurium-hyperdoped Si for infrared optoelectronics

Wang, M.; Shaikh, M. S.; Berencen, Y.; Hübner, R.; Helm, M.; Prucnal, S.; Zhou, S.

Abstract

In this work, we report on the preparation of Te-hyperdoped Si. The hyperdoped Si layers are homogeneous, do not show cellular breakdown, and have a flat surface. Based on the obtained materials, we demonstrate a room-temperature mid-wavelength infrared Si p-n photodiode working in photovoltaic mode. The fabricated photodiode exhibits enhanced performance, e.g. regarding spectral photoresponse, specific detectivity, bandwidth and response speed. Moreover, inherited from the high free carrier concentration, mid-infrared-localized surface plasmon resonances (LSPR) are also observed in hyperdoped Si. We show that the mid-infrared LSPR can be further enhanced and spectrally extended to the far-infrared range by fabricating two-dimensional arrays of micrometer-sized antennas on a Te-hyperdoped Si chip. Since Te-hyperdoped Si can also work as an infrared photodetector, we believe that our results will unlock the route toward the direct integration of plasmonic sensors within a one-chip CMOS platform, greatly advancing the possibility of mass manufacturing of Si-based infrared photonic systems.

Involved research facilities

Related publications

  • Lecture (Conference)
    ISTDM-ICSI-2023, 21.-25.05.2023, Como, Italy

Permalink: https://www.hzdr.de/publications/Publ-37082


Optimizing Magneto-ionic Performance in Structure/Composition-Engineered Ternary Nitrides

Ma, Z.; Peda, M.; Tan, Z.; Pellicer, E.; Liedke, M. O.; Butterling, M.; Elsherif, A. G. A.; Hirschmann, E.; Wagner, A.; Ibrahim, F.; Chshiev, M.; Menéndez, E.; Sort, J.

Abstract

Magneto-ionics, an emerging approach to manipulate magnetism that relies on voltage-driven ion motion, holds the promise to boost energy efficiency in information technologies such as spintronic devices or future non-von Neumann computing architectures. For this purpose, stability, reversibility, endurance, and ion motion rates need to be synergistically optimized. Among various ions, nitrogen has demonstrated superior magneto-ionic performance compared to classical species such as oxygen or lithium. Here, we show that ternary Co1−xFexN compound exhibits an unprecedented nitrogen magneto-ionic response. Partial substitution of Co by Fe in binary CoN is shown to be favorable in terms of generated magnetization, cyclability and ion motion rates. Specifically, the Co0.35Fe0.65N films exhibit an induced saturation magnetization of 1500 emu cm–3, a magneto-ionic rate of 35.5 emu cm–3 s–1 and
endurance exceeding 103 cycles. These values significantly surpass those of other existing nitride and oxide systems. This improvement can be attributed to the larger saturation magnetization of Co0.35Fe0.65 compared to individual Co and Fe, the nature and size of structural defects in as-grown films of different composition, and the dissimilar formation energies of Fe and Co with N in the various developed crystallographic structures.

Keywords: magneto-ionics; voltage control of magnetism; electrolyte gating; ternary nitrides; ion transport; positron annihilation spectroscopy

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-37081


Probing Protein Hydration with Terahertz Spectroscopy

Adams, E.

Abstract

In recent years the importance of the aqueous solvent in influencing protein structure, function, and dynamics has been recognized. Coupling of water molecules to the protein surface results in an interfacial region in which water molecules within this region have distinctly different properties than bulk water. However, the structure and dynamics within this interfacial region are still not easy to access experimentally. Terahertz (THz) spectroscopy has been shown to be a powerful tool to investigate solvent dynamics in bulk solutions. Radiation in the THz regime is directly sensitive to the low frequency collective intermolecular hydrogen-bonding vibrations of water (0.3-6 THz or 10-200 cm-1), and thus to any changes in the hydrogen-bonding network. Changes in these sub-picosecond collective motions, such as protein-water interactions, result in changes in the measured THz absorption. Individual hydrations shells of proteins have been shown to contribute largely to structure-function relationships and ultimately modulate the binding properties of proteins. Here the role of solvation dynamics in processes such as electron transport in protein complexes and enzymatic catalysis will be investigated.

  • Invited lecture (Conferences)
    9th Summer School Solvation Science, 30.05.-02.06.2023, Bochum, Germany

Permalink: https://www.hzdr.de/publications/Publ-37080


Nonlinear Transmission of FUS Protein Solution at 0.5 THz

Thai, Q.-M.; Ilyakov, I.; Raj, M.; Dornbusch, D.; Arshad, A.; de Oliveira, T.; Jahnel, M.; Deinert, J.-C.; Ponomarev, A.; Kovalev, S.; Adams, E.

Abstract

Water possesses strong absorption in the THz range due to intermolecular vibrational modes in a network of hydrogen-bonded water molecules. Its THz response is also sensitive to the coupling of water to other molecules, i.e. the hydration shell of a protein. Probing the nonlinear properties of hydration water can provide insight into protein solvent dynamics, and in the case of intrinsically disordered proteins, its subsequent role in the liquid-liquid phase separation (LLPS). Such characterization at low THz frequencies (< 3 THz) remains yet limited, due to the scarcity of brilliant light sources in this range. Here, we present the nonlinear characterization at 0.5 THz of water and FUS protein solution in a liquid transmission cell, using a THz time-domain spectroscopy (THz-TDS) setup with the TELBE free electron laser source at HZDR. Our results show that the nonlinear absorption and refractive indices of the FUS protein solution differ from that of water, indicating a perturbed hydrogen bonding network.

Involved research facilities

Related publications

  • Poster
    DPG Spring Meeting Condensed Matter Section, 26.-30.03.2023, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-37079


Solvation Properties in Biomolecular Condensates

Adams, E.

Abstract

In recent years the importance of the aqueous solvent in influencing protein structure, function, and dynamics has been recognized. Coupling of water molecules to the protein surface results in an interfacial region in which water molecules within this region have distinctly different properties than bulk water. However, the structure and dynamics within this interfacial region are still not easy to access experimentally. Terahertz (THz) spectroscopy has been shown to be a powerful tool to investigate solvent dynamics in bulk solutions. Radiation in the THz regime is directly sensitive to the low frequency collective intermolecular hydrogen-bonding vibrations of water (0.3-6 THz or 10-200 cm-1), and thus to any changes in the hydrogen-bonding network. Changes in these sub-picosecond collective motions, such as protein-water interactions, result in changes in the measured THz absorption. Individual hydrations shells of proteins have been shown to contribute largely to structure-function relationships and ultimately modulate the binding properties of proteins. Here the role of solvation dynamics in the liquid-liquid phase separation (LLPS) of the intrinsically disordered protein fused in sarcoma (FUS) is probed. Characterization of the hydrogen bonding network reveals that water solvating hydrophobic groups is stripped away in the membrane-less FUS biomolecular condensates. Additionally, water left inside of the biomolecular condensates is highly constrained, indicative of a population of bound hydration water. These results uncover the vital role of hydration water in LLPS: the entropically favorable release of unfavorable hydration water serves as a driving force for LLPS.

  • Invited lecture (Conferences)
    6th Conference on Frontiers in Water Biophysics, 19.-24.05.2023, Erice, Italy

Permalink: https://www.hzdr.de/publications/Publ-37078


Key Role of the Solvent in Driving Liquid-Liquid Phase Separation

Adams, E.; Ahlers, J.; Bader, V.; Pezzotti, S.; Winklhofer, K. F.; Tatzelt, J.; Havenith, M.

Abstract

In recent years the importance of the aqueous solvent in influencing protein structure, function, and dynamics has been recognized. Coupling of water molecules to the protein surface results in an interfacial region in which water molecules within this region have distinctly different properties than bulk water. However, the structure and dynamics within this interfacial region are still not easy to access experimentally. Terahertz (THz) spectroscopy has been shown to be a powerful tool to investigate solvent dynamics in bulk solutions. Radiation in the THz regime is directly sensitive to the low frequency collective intermolecular hydrogen-bonding vibrations of water (0.3-6 THz or 10-200 cm-1), and thus to any changes in the hydrogen-bonding network. Here the role of solvation dynamics in the liquid-liquid phase separation (LLPS) of the intrinsically disordered protein fused in sarcoma (FUS) is probed. Characterization of the hydrogen bonding network reveals that water solvating hydrophobic groups is stripped away in the membrane-less FUS biomolecular condensates. Additionally, water left inside of the biomolecular condensates is highly constrained, indicative of a population of bound hydration water. These results uncover the vital role of hydration water in LLPS: the entropically favorable release of unfavorable hydration water serves as a driving force for LLPS.

  • Lecture (Conference)
    DPG Spring Meeting Condensed Matter Section, 26.-30.03.2023, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-37077


Physics-enhanced neural networks for equation-of-state calculations

Callow, T. J.; Kraisler, E.; Cangi, A.

Abstract

Rapid access to accurate equation-of-state (EOS) data is crucial in the warm-dense matter regime, as it is employed in various applications, such as providing input for hydrodynamics codes to model inertial confinement fusion processes. In this study, we develop neural network models for predicting the EOS based on first-principles data. The first model utilizes basic physical properties, while the second model incorporates more sophisticated physical information, using output from average-atom calculations as features. Average-atom models are often noted for providing a reasonable balance of accuracy and speed; however, our comparison of average-atom models and higher-fidelity calculations shows that more accurate models are required in the warm-dense matter regime. Both the neural network models we propose, particularly the physics-enhanced one, demonstrate significant potential as accurate and efficient methods for computing EOS data in warm-dense matter.

Keywords: Machine learning; Equation of state; High-energy density science; Neural network; Warm dense matter; First-principles calculations; Density functional theory; Average-atom models

Permalink: https://www.hzdr.de/publications/Publ-37075


Improving dynamic collision frequencies: Impacts on dynamic structure factors and stopping powers in warm dense matter

Hentschel, T. W.; Kononov, A.; Olmstead, A.; Cangi, A.; Baczewski, A. D.; Hansen, S. B.

Abstract

Simulations and diagnostics of high-energy-density plasmas and warm dense matter rely on models of material response properties, both static and dynamic (frequency-dependent). Here, we systematically investigate variations in dynamic electron–ion collision frequencies ν(ω) in warm dense matter using data from a self-consistent-field average-atom model. We show that including the full quantum density of states, strong collisions, and inelastic collisions lead to significant changes in ν(ω) ⁠. These changes result in red shifts and broadening of the plasmon peak in the dynamic structure factor, an effect observable in x-ray Thomson scattering spectra, and modify stopping powers around the Bragg peak. These changes improve the agreement of computationally efficient average-atom models with first-principles time-dependent density functional theory in warm dense aluminum, carbon, and deuterium.

Keywords: Matter under extreme conditions; High-energy density science; Density functional theory; Time-dependent density functional theory; Average-atom models; Warm dense matter; Collision frequencies; X-ray Thomson scattering

Permalink: https://www.hzdr.de/publications/Publ-37074


Data publication: Millisecond Flash Lamp Curing for Porosity Generation in Thin Films

Attallah, A. G.; Prucnal, S.; Butterling, M.; Hirschmann, E.; Koehler, N.; Schulz, S. E.; Wagner, A.; Liedke, M. O.

Abstract

Research data of Millisecond Flash Lamp Curing for Porosity Generation in Thin Films

Involved research facilities

  • P-ELBE

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Permalink: https://www.hzdr.de/publications/Publ-37073


Performance portability for the CMS Reconstruction with Alpaka

Bocci, A.; Czirkos, A.; Di Pilato, A.; Pantaleo, F.; Hugo, G.; Kortelainen, M.; Redjeb, W.

Abstract

For CMS, Heterogeneous Computing is a powerful tool to face the computational challenges posed by the upgrades of the LHC, and will be used in production at the High Level Trigger during Run 3. In principle, to offload the computational work on non-CPU resources, while retaining their performance, different implementations of the same code are required. This would introduce code-duplication which is not sustainable in terms of maintainability and testability of the software. Performance portability libraries allow to write code once and run it on different architectures with close-to-native performance. The CMS experiment is evaluating performance portability libraries for the near term future.

Keywords: CMS; alpaka; heterogeneous programming; C++; CUDA; software portability; GPGPU; parallel programming; LHC; offloading

  • Open Access Logo Contribution to proceedings
    20th International Workshop on Advanced Computing and Analysis Techniques in Physics Research (ACAT 2021), 29.11.-03.12.2021, Daejeon, Daehan Minguk
    Journal of Physics: Conference Series Vol. 2438, Bristol, United Kingdom: IOP Publishing Ltd.
    DOI: 10.1088/1742-6596/2438/1/012058
    Cited 1 times in Scopus

Permalink: https://www.hzdr.de/publications/Publ-37072


Helmholtz Metadata Collaboration (HMC) – FAIR Metadata for Energy

Süß, W.; Schweikert, J.; Stucky, K.-U.; Koubaa, M. A.; Steinmeier, L.; Ballani, F.; Hoyer-Klick, C.

Abstract

The Helmholtz Metadata Collaboration (HMC) is an initiative that provides support for researchers within the Helmholtz Association to create, manage, and use metadata effectively and to establish FAIR data as the new standard for working with data in science. The HMC provides services, advice, and training on how to identify and apply appropriate metadata standards and schemas, how to design and implement metadata workflows, and to develop strategies for data discovery and reuse. Six metadata hubs according to the Helmholtz association's six research areas have been established to meet the specific needs of the respective communities. This presentation is given by the Hub Energy to communicate the HMC's efforts and offers for the research data in the field Energy and to its research community

Keywords: Helmholtz Metadata Collaboration; FAIR; Metadata; Energy

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

Permalink: https://www.hzdr.de/publications/Publ-37071


Energy Metadata Management to Establish FAIR Data as a New Standard

Süß, W.; Hoyer-Klick, C.; van den Boogaart, K. G.; Stucky, K.-U.; Schweikert, J.; Koubaa, M. A.; Steinmeier, L.; Ballani, F.

Abstract

Open Science implies sharing data for the reuse in other research context. For data to be reusable, it needs proper documentation, which is usually done through metadata. Metadata and its management are a critical component of ensuring that energy data is FAIR (Findable, Accessible, Interoperable, and Reusable). Metadata is information about data, such as its format, origin, and purpose, that helps users understand and use the data effectively.
One of the key challenges of managing energy data is the variety of sources, including sensors, simulations, and experiments. This means that the data may be in different formats, with different levels of detail, and with different levels of quality. Metadata help to standardize and harmonize the data, making it easier to find, access, and use them.
Another key benefit of metadata management is that it allows energy data to be more easily shared and reused. By providing detailed information about the data, including its provenance, quality, and limitations, metadata management helps to ensure that the data is used appropriately. This is particularly important in the energy sector, where data is often used to guide policy and investment decisions.
The use of standard vocabularies and ontologies is beneficial for describing the available research data in a consistent way, making it easier to search and retrieve them.
In conclusion, elaborated metadata management in a way described above, is an essential component of ensuring that energy data is compatible with the principles of FAIR.
The Helmholtz Metadata Collaboration (HMC) is an initiative that provides support for researchers within the Helmholtz Association to create, manage, and use metadata effectively and to establish FAIR data as the new standard for working with data in science. The HMC provides services, advice, and training on how to identify and apply appropriate metadata standards and schemas, how to design and implement metadata workflows, and to develop strategies for data discovery and reuse.
The HMC can support researchers in various ways, such as:
1. Standard and schema identification: The HMC can help researchers to identify the most suitable metadata standards and schemas for their research data, and to apply them correctly. This will ensure that data can be easily discovered and reused by others.
2. Metadata workflows: The HMC can assist researchers in designing and implementing metadata workflows that are tailored to their specific research needs. This can help to ensure that data is properly described and indexed, and that metadata is created in a consistent and accurate manner.
3. Data discovery and reuse: The HMC can help researchers to develop strategies for making their data discoverable and reusable by others. This includes creating metadata records, depositing data in repositories, and making data available through data catalogs or research data management platforms.
4. Tool and service integration: The HMC can support researchers in integrating their metadata with other data management tools and services, such as data repositories, data catalogs, and research data management platforms. This will help to ensure that data is easily discoverable, accessible, and reusable.
5. Providing training and support: The HMC offers training and support to researchers to help them create, manage, and use metadata effectively. This is done by offering a variety of workshops, webinars, and one-on-one support.
Overall, the HMC aims to foster a culture of good data management practices within the Helmholtz community and to support the discovery, access, and reuse of research data across the Helmholtz association. The HMC is committed to help researchers in their metadata management processes, and to make sure that their data is discoverable, accessible, and reusable by others. Six metadata hubs according to the Helmholtz association's six research areas have been established to meet the specific needs of the respective communities. This presentation is given by the Hub Energy to communicate the HMC's efforts and offers for the research data in the field Energy and to its research community

Keywords: Energy; Metadata; FAIR Data

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

Permalink: https://www.hzdr.de/publications/Publ-37070


Intracellular biocompatible hexagonal boron nitride quantum emitters as single-photon sources and barcodes

Kavčič, A.; Podlipec, R.; Vella, D.; Humar, M.

Abstract

Color centers in hexagonal boron nitride (hBN) have been emerging as a multifunctional platform for various optical applications including quantum information processing, quantum computing and imaging. Simultaneously, due to its biocompatibility and biodegradability hBN is a promising material for biomedical applications. In this work, we demonstrate single-photon emission from hBN color centers embedded inside live cells and their application to cellular barcoding. The generation and internalization of multiple color centers into cells was performed via simple and scalable procedure while keeping the cells unharmed. The emission from live cells was observed as multiple diffraction-limited spots, which exhibited excellent single-photon characteristics with high single-photon purity of 0.1 and superb mission stability without photobleaching or spectral shifts over several hours. Due to different emission wavelengths and peak widths of the color centers, they were employed as barcodes. Each color center can exist in one out of 470 possible distinguishable states and a combination of a few color centers per cell can be used to uniquely tag virtually an unlimited number of cells. This barcoding technique is superior to others in almost all respects, including ease of production by a single-step procedure, biocompatibility and biodegradability, emission stability, no photobleaching, small size and a huge number of unique barcodes. This work provides a basis for the use of hBN color centers for robust barcoding of cells and due to the single photon emission, presented concepts could in future be extended to quantum-limited sensing and super-resolution imaging.

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Permalink: https://www.hzdr.de/publications/Publ-37069


Ways for Efficient Decommissioning of Reactor Components and Concrete Shielding

Pönitz, E.; Roode-Gutzmer, Q. I.; Barkleit, A.; Konheiser, J.

Abstract

Due to Germany’s nuclear phase-out, the decommissioning of nuclear power plants (NPPs) and final disposal of structural materials becomes an increasingly important task. The project WERREBA (German acronym for Ways for Efficient Decommissioning of Reactor Components and Concrete Shielding) aimed at the reliable determination of radionuclides produced by neutron activation, the activity as a function of time since shutdown and investigating subsequent radionuclide mobility. In the scope of the project, activity measurements and calculations were carried out for samples of the reactor pressure vessel and the concrete shielding of unit 2 of the Greifswald NPP shut down in 1990 during the German reunification.
Both measurements and calculations show that the highest specific activity of the RPV is found in a small region adjacent to the reactor core. Several decades after shutdown, Cobalt-60 (half-live time 5.27 y) is the dominating nuclide. A prolongation of the interim storage time by several years, i.e. caused by the delayed start of the operation phase of the Konrad repository, will therefore lead to a significant reduction of the activity of the structural materials. The specific activity decreases by 4 to 5 orders of magnitude with increasing distance to the reactor core. It is expected that a specific clearance or even unrestricted clearance will be possible for parts of the RPV after several decades of interim storage time.
Unit 2 of the Greifswald NPP is a first-generation VVER-440 (Russian acronym for pressurized water reactor with light water as coolant and moderator) which features an annular water tank. A neutron radiation field calculation using the radiation transport code MCNP reveals that the maximum neutron fluence in the concrete component is located in the floor just below the RPV. The concrete structures closest to the reactor core are shielded efficiently against neutron radiation by the annular water tank.
Measured and calculated specific activities of Europium-152, Europium-154 and Cobalt-60 for the cement screed at the position of the maximum neutron fluence are surprisingly low compared to recently published calculations and measurements for VVER-440 of the second generation. This is attributed primarily to the distinct design of the first generation VVER-440/230 compared with the second generation VVER-440/213 without annular water tank.

Keywords: decommissioning of nuclear facilities; VVER-440; MCNP

  • Lecture (Conference)
    Helmholtz Energy Conference 2023, 12.-13.06.2023, Koblenz, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37068


Experimental investigation of Taylor bubble in narrow tubes with constrictions

Maestri, R.; Bürkle, F.; Büttner, L.; Czarske, J.; Hampel, U.; Lecrivain, G.

Abstract

Gas Taylor bubbles in millichannels are characterized by an elongated shape, bullet-shaped bubbles nose and a comparatively flat bottom. Because of dominant interfacial tension forces, such bubbles occupy most of the cross-sectional area of the tube. There exist many experimental or numerical investigations. Most of them consider Taylor bubbles moving in a straight pipe with constant cross-section, such as a tube or square duct. In this work, we report a new finding for a vertical tube equipped with a geometrical singularity. The dynamics of an individual Taylor bubble in a counter-current flow is presently investigated. We find that a small tube constriction, with only 5 % obstruction, has a significant influence on the flow and interfacial dynamics. Various regimes, characterized for increasing channel obstruction, are here established. High experimental and numerical reproducibility is observed.

Keywords: Interfacial flow; Taylor bubble; Two-phase flow; Obstruction; Milli-channel

  • Lecture (Conference)
    Gesellschaft für angewandte Mathematik und Mechanik, 30.05.-02.06.2023, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-37067


Microscopy image reconstruction with physics-informed denoising diffusion probabilistic model

Li, R.; Della Maggiora, G.; Andriasyan, V.; Petkidis, A.; Yushkevich, A.; Kudryashev, M.; Yakimovich, A.

Abstract

Light microscopy is a widespread and inexpensive imaging technique facilitating biomedical discovery and diagnostics. However, light diffraction barrier and imperfections in optics limit the level of detail of the acquired images. The details lost can be reconstructed among others by deep learning models. Yet, deep learning models are prone to introduce artefacts and hallucinations into the reconstruction. Recent state-of-the-art image synthesis models like the denoising diffusion probabilistic models (DDPMs) are no exception to this. We propose to address this by incorporating the physical problem of microscopy image formation into the model's loss function. To overcome the lack of microscopy data, we train this model with synthetic data. We simulate the effects of the microscope optics through the theoretical point spread function and varying the noise levels to obtain synthetic data. Furthermore, we incorporate the physical model of a light microscope into the reverse process of a conditioned DDPM proposing a physics-informed DDPM (PI-DDPM). We show consistent improvement and artefact reductions when compared to model-based methods, deep-learning regression methods and regular conditioned DDPMs.

Keywords: deep learning; denoising diffusion probabilistic model; superresolution microscopy; physics-informed neural networks

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Permalink: https://www.hzdr.de/publications/Publ-37066


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

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

Abstract

Data for all figures of publication: " Ultra-short pulse laser acceleration of protons to 80 MeV from cryogenic hydrogen
jets tailored to near-critical density". The folder structure is adapted to match the figures in the publication.

Keywords: Plasma accelerator; Laser ion acceleration; Near-critical density plasmas

Involved research facilities

  • Draco

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Permalink: https://www.hzdr.de/publications/Publ-37065


Dimer Coupling Energies of the Si(001) Surface

Brand, C.; Hucht, A.; Jnawali, G.; Fortmann, J. D.; Sothmann, B.; Mehdipour, H.; Kratzer, P.; Schützhold, R.; Horn-Von Hoegen, M.

Abstract

The coupling energies between the buckled dimers of the Si(001) surface were determined through analysis of the anisotropic critical behavior of its order-disorder phase transition. Spot profiles in high-resolution low-energy electron diffraction as a function of temperature were analyzed within the framework of the anisotropic two-dimensional Ising model. The validity of this approach is justified by the large ratio of correlation lengths, ζ +/ζ∥+=5.2 of the fluctuating c(4×2) Domains above the critical temperature Tc=(190.6±10) K. We obtain effective couplings J∥=(-24.9±1.3) meV along the dimer rows and J⊥=(-0.8±0.1) meV across the dimer rows, i.e., antiferromagneticlike coupling of the dimers with c(4×2) symmetry.

Keywords: Dimers; Electrons; Ising model; Correlation lengths; Coupling energies; Critical behaviour; Critical temperatures; Effective coupling; High resolution; Low-energy electron diffraction; Order/disorder phase transition; Spot profile; Two-dimensional; Anisotropy

Permalink: https://www.hzdr.de/publications/Publ-37064


Fresh look at experimental evidence for odderon exchange

Schmidt, S. M.; Cui, Z.-F.; Binosi, D.; Roberts, C. D.; Triantafyllopoulos, D. N.

Abstract

Theory suggests that in high-energy elastic hadron+hadron scattering, t-channel exchange of a family of colourless crossingodd
states – the odderon – may generate differences between pp¯ and pp cross-sections in the neighbourhood of the
diffractive minimum. Using a mathematical approach based on interpolation via continued fractions enhanced by statistical
sampling, we develop robust comparisons between pp¯ elastic differential cross-sections measured at √s=1.96 TeV by the
D0 Collaboration at the Tevatron and function-form-unbiased extrapolations to this energy of kindred pp measurements at
√s/TeV=2.76,7,8,13 by the TOTEM Collaboration at the LHC and a combination of these data with earlier cross-section
measurements at √s/GeV=23.5,30.7,44.7,52.8,62.5 made at the intersecting storage rings. Focusing on a domain that
straddles the diffractive minimum in the pp¯ and pp cross-sections, we find that these two cross-sections differ at the
(2.2−2.6)σ level; hence, supply evidence with this level of significance for the existence of the odderon. If combined with
evidence obtained through different experiment-theory comparisons, whose significance is reported to lie in the range
(3.4−4.6)σ, one arrives at a (4.0−5.2)σ signal for the odderon.

Keywords: Diffractive processes; High-energy hadron; Odderon; Regge phenomenology; Schlessinger point; Strong interactions in the standard model of particle physics; hadron interactions

Permalink: https://www.hzdr.de/publications/Publ-37063


B20 Weyl semimetal CoSi film fabricated by flash-lamp annealing

Li, Z.; Yuan, Y.; Hübner, R.; Rebohle, L.; Zhou, Y.; Helm, M.; Nielsch, K.; Prucnal, S.; Zhou, S.

Abstract

B20-CoSi is a newly discovered Weyl semimetal that crystallizes into a non-centrosymmetric crystal structure. However, the investigation of B20-CoSi has so far been focused on bulk materials, whereas the growth of thin films on technology-relevant substrates is a prerequisite for most practical applications. In this study, we have used millisecond-range flash-lamp annealing, a non-equilibrium solid-state reaction, to grow B20-CoSi thin films. By optimizing the annealing parameters, we were able to obtain thin films with a pure B20-CoSi phase. The magnetic and transport measurements indicate the appearance of the charge density wave and the chiral anomaly. Our work presents a promising method for preparing thin films of most binary B20 transition-metal silicides, which are candidates for topological Weyl semimetals.

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37062


Data and Software - Synchronizing the Rayleigh-Benard Instability in a Liquid Metal Flow Using Electromagnetic Forces

Jüstel, P.
Researcher: Zürner, Till; Researcher: Schindler, Felix; Researcher: Röhrborn, Sebastian

Abstract

Data and software of the dissertation (to be) submitted to TU Ilmenau by Peter Jüstel.

Keywords: Python; Scientific Research Software Architecture

Downloads

Permalink: https://www.hzdr.de/publications/Publ-37061


Controlling Solute Channel Formation using Magnetic Fields

Fan, X.; Shevchenko, N.; Tonry, C.; Clark, S. J.; Atwood, R. C.; Eckert, S.; Pericleous, K.; Lee, P. D.; Kao, A.

Abstract

Solute channel formation introduces compositional and microstructural variations in a range of processes, from metallic alloy solidification to salt fingers in ocean and water reservoir flows. Applying an external magnetic field interacts with thermoelectric currents at solid/liquid interfaces generating additional flow fields. This thermoelectric (TE) magnetohydrodynamic (TEMHD) effect can impact on solute channel formation ,via a mechanism recently drawing increasing attention. To investigate this phenomenon, we combined in situ synchrotron X-ray imaging and Parallel Cellular Automata Lattice Boltzmann method-based numerical simulations to study the characteristics of flow and solute transport under TEMHD. Observations suggest the macroscopic TEMHD flow appearing ahead of the solidification front, coupled with the microscopic TEMHD flow arising within the mushy zone are the primary mechanisms controlling plume migration and channel bias. Two TE regimes were revealed, each with distinctive mechanisms that dominate the flow. Further, we show that grain orientation modifies solute flow through anisotropic permeability. These insights led to a proposed strategy for producing solute channel-free solidification using a time-modulated magnetic field.

Keywords: Directional solidification; Solute channel; Magnetic field; Thermoelectric magnetohydrodynamic

Permalink: https://www.hzdr.de/publications/Publ-37060


Local Polymorph Conversion in Gallium Oxide via Focused Ion Beam Irradiation

Bektas, U.; Chekhonin, P.; Klingner, N.; Liedke, M. O.; Heller, R.; Hübner, R.; Ganss, F.; Hlawacek, G.

Abstract

Monoclinic gallium oxide (β-Ga2O3) exhibits the highest chemical and thermal
stability among its four other polymorphs, making it a highly promising
semiconductor material for various applications such as power electronics,
optoelectronics, and batteries, thanks to its exceptionally wide bandgap of around
4.7 eV. However, the challenge lies in effectively managing the metastable
polymorph phases and dealing with underdeveloped nanoscale fabrication
techniques. Our objective is to leverage the potential of ion-beam-induced polymorph
conversion to gain a comprehensive understanding and control over the crystalline
structure. By utilizing focused ion beams (FIBs), we aim to pioneer new fabrication
methods for generating single-phase polymorph layers, buried layers, multilayers,
and diverse nanostructures within Ga2O3. The primary focus of this research is to
enhance our knowledge and control of polymorph conversion, with a particular
emphasis on spatially precise modifications using focused ion beams.
Most semiconductor materials transform into an amorphous phase under a high
dose of ion irradiation, however, Ga2O3 is an exceptionally radiation-tolerant material
even at high fluences of ion irradiation. The conversion from the stable to the
metastable phase seems to be enabled by the formation of a defective spinel
structure in which the oxygen lattice remains unchanged [1]. It has been found that
sub-lattice requires a certain level of damage accumulation, specifically
displacement per atom (DPA), to transform into γ-phase [1].
Here, we used Helium Ion Microscopy (HIM) and liquid metal alloy ion source
(LMAIS) FIBs to locally irradiate (-201) -oriented β-Ga2O3 substrate with different
ions (Ne, Ga, Co, Nd, Si, Au, In) to induce the polymorph transition. Locally and
spatially resolved characterization was performed by Electron Backscatter Diffraction
(EBSD) and analyzing the Kikuchi patterns. Furthermore, Doppler Broadening
Variable Energy Positron Annihilation Spectroscopy (DB-VEPAS) and Rutherford
Backscatter Spectrometry (RBS) were performed for neon-broad-beam-irradiated
implants to better understand the fluence-dependent creation and distribution of
defects. Transmission Electron Microscopy (TEM) images provide information about
the interfaces between different polymorphs of Ga2O3. The first results indicate that
the damage/strain created by the Ne+, Co+, and Si+ FIB irradiations leads to a local
transformation of β- Ga2O3 to γ- Ga2O3 and the structure maintains its crystallinity
up to high-fluence FIB irradiation instead of being amorphized.

Keywords: Gallium Oxide; Helium Ion Microscopy; Focused Ion Beam; Positron Annihilation Lifetime Spectroscopy; Polymorph Transition; Transmission Electron Microscopy; Electron Backscatter Diffraction; Rutherford backscatter spectroscopy

Involved research facilities

Related publications

  • Open Access Logo Lecture (Conference)
    E-MRS 2023 Fall Meeting, 18.-21.09.2023, Warsaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-37059


Software for Fate of bubble clusters rising in a quiescent liquid

Ma, T.; Hessenkemper, H.; Lucas, D.; Bragg, A. D.

Abstract

The repository contains the tracking software for Fate of bubble clusters rising in a quiescent liquid. Please refer to the README.md for installation instruction.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-37058


Dataset for Fate of bubble clusters rising in a quiescent liquid

Ma, T.; Hessenkemper, H.; Lucas, D.; Bragg, A. D.

Abstract

This repository contains the training data for Fate of bubble clusters rising in a quiescent liquid. Sequence 18, 19, 33 and 37 were used for validation. The structure is as follows: The Images folder contains the semi-artificial image sequences, the GTMask folder contains semantic masks with the same ID (gray value) for the same bubble, Nodes.pkl contains the prediction generated with the detection method described in "Bubble identification from images with machine learning methods" and NodesGT.pkl the corresponding ground truth needed for training. You can use GTMask or NodesGT.pkl to train/test your own tracking model.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-37057


Ultrasonic Investigation of the Magnetic Ordering in Er3Ru4Al12 with a Distorted Kagome Lattice

Ishii, I.; Kurata, Y.; Muneshige, H.; Andreev, A. A.; Gorbunov, D.; Nohara, M.; Suzuki, T.

Abstract

To investigate a phase transition around 2 K in Er3Ru4Al12 with a distorted kagome lattice, we conducted the specific heat, magnetic susceptibility, and ultrasonic measurements. At zero field a sharp peak of the specific heat is observed at TN = 2.2 K, implying a phase transition. The magnetic susceptibility in a field applied along [100], which is a magnetically easy direction, remains almost the same value below TN. The longitudinal elastic modulus, C11, shows an obvious hardening at TN, and TN decreases up to 0.4 T as the magnetic field applied along [100] increases, suggesting an antiferromagnetic ordering. In the magnetic field dependence of C11 at 0.5 K, we discovered two abrupt softenings at 0.25 T and around 0.47 T, proposing that the antiferromagnetic phase boundary closes around 0.47 T in the field applied along [100]. Other phase boundary exists around 0.25 T in the ordered state

Involved research facilities

  • High Magnetic Field Laboratory (HLD)
  • Open Access Logo Contribution to proceedings
    29th International Conference on Low Temperature Physics (LT29), 18.-24.08.2022, Sapporo, Japan
    JPS Conference Proceedings - Proc. 29th Int. Conf. Low Temperature Physics (LT29): JPS
    DOI: 10.7566/JPSCP.38.011106

Permalink: https://www.hzdr.de/publications/Publ-37054


Change in the Ground State of Y1−xPrxIr2Zn20 due to a Quadrupolar Kondo Effect with Pr Concentration x

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

Abstract

We measured the elastic constants (C11 − C12) /2 and C44 of the non-Kramers system Y0.92Pr0.08Ir2Zn20 (Pr-8% system) by means of ultrasound to check how the single-site quadrupolar Kondo effect is modulated by increasing the Pr concentration. In the Pr-8% system, a temperature dependence proportional to √T is observed in (C11 − C12) /2 below ∼ 0.5 K. This behavior rather corresponds to the theoretical prediction of the quadrupolar Kondo virtual “lattice” model, unlike that of a Pr-3.4% system, which shows a logarithmic temperature dependence based on the “single-site” quadrupolar Kondo theory. Such temperature dependence proportional to √T is also observed in a Pr-37% system below 0.15 K, which suggests that a crossover of the quantum ground state from the “single-site” model to the “lattice” model occurs as the localized quadrupolar interaction cannot be ignored with increasing Pr concentration.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)
  • Open Access Logo Contribution to proceedings
    29th International Conference on Low Temperature Physics (LT29), 18.-24.08.2022, Sapporo, Japan
    JPS Conference Proceedings - Proc. 29th Int. Conf. Low Temperature Physics (LT29): JPS
    DOI: 10.7566/JPSCP.38.011089

Permalink: https://www.hzdr.de/publications/Publ-37053


A Trinuclear High-Spin Iron(III) Complex with a Geometrically Frustrated Spin Ground State Featuring Negligible Magnetic Anisotropy and Antisymmetric Exchange

Kintzel, B.; Böhme, M.; Plaul, D.; Görls, H.; Yeche, N.; Seewald, F.; Klauss, H.-H.; Zvyagin, A. A.; Kampert, W. A. G.; Herrmannsdörfer, T.; Pascua, G.; Baines, C.; Luetkens, H.; Plass, W.

Abstract

The trinuclear high-spin iron(III) complex [Fe3Cl3(saltagBr)(py)6]ClO4 {H5saltagBr = 1,2,3-tris[(5-bromo-salicylidene)amino]guanidine} was synthesized and characterized by several experimental and theoretical methods. The iron(III) complex exhibits molecular 3-fold symmetry imposed by the rigid ligand backbone and crystallizes in trigonal space group P3̅ with the complex cation lying on a crystallographic C3 axis. The high-spin states (S = 5/2) of the individual iron(III) ions were determined by Mösbauer spectroscopy and confirmed by CASSCF/CASPT2 ab initio calculations. Magnetic measurements show an antiferromagnetic exchange between the iron(III) ions leading to a geometrically spin-frustrated ground state. This was complemented by high-field magnetization experiments up to 60 T, which confirm the isotropic nature of the magnetic exchange and negligible single-ion anisotropy for the iron(III) ions. Muon-spin relaxation experiments were performed and further prove the isotropic nature of the coupled spin ground state and the presence of isolated paramagnetic molecular systems with negligible intermolecular interactions down to 20 mK. Broken-symmetry density functional theory calculations are consistent with the antiferromagnetic exchange between the iron(III) ions within the presented trinuclear high-spin iron(III) complex. Ab initio calculations further support the absence of appreciable magnetic anisotropy (D = 0.086, and E = 0.010 cm−1) and the absence of significant contributions from antisymmetric exchange, as the two Kramers doublets are virtually degenerate (ΔE = 0.005 cm−1). Therefore, this trinuclear high-spin iron(III) complex should be an ideal candidate for further investigations of spin-electric effects arising exclusively from the spin chirality of a geometrically frustrated S = 1/2 spin ground state of the molecular system.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-37052


Magnetic field induced reentrant multipolar ordering in the distorted kagome-lattice antiferromagnet Dy3Ru4Al12

Ishii, I.; Suzuki, T.; Andreev, A. V.; Mitsumoto, K.; Araki, K.; Miyata, A.; Gorbunov, D.; Zherlitsyn, S.; Wosnitza, J.

Abstract

We report on ultrasonic and magnetocaloric-effect measurements of the hexagonal antiferromagnet Dy3Ru4Al12 having a distorted kagome lattice. We observed a pronounced softening of the transverse modulus, C44, above 30 T applied along [100], indicating an as-yet-unidentified magnetic field induced phase transition. We determined the field-temperature phase diagrams using pulsed magnetic fields up to 55.2 T, applied along [100] and [001]. Optimizing crystal-electric-field parameters within the mean-field approximation, we conclude that the enhancement of the field induced phase-transition temperature is due to electric quadrupolar and magnetic octupolar mediated interactions. We propose that the order parameter of the magnetic field induced phase transitions is the electric quadrupole Ozx, facilitated by octupole-mediated interactions.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-37051


Restoring Axonal Organelle Motility and Regeneration in Cultured FUS-ALS Motoneurons through Magnetic Field Stimulation Suggests an Alternative Therapeutic Approach

Kandhavivorn, W.; Glaß, H.; Herrmannsdörfer, T.; Böckers, T. M.; Uhlarz, M.; Gronemann, J.; Funk, R. H. W.; Pietzsch, J.; Pal, A.; Hermann, A.

Abstract

Amyotrophic lateral sclerosis (ALS) is a devastating motoneuron disease characterized by sustained loss of neuromuscular junctions, degenerating corticospinal motoneurons and rapidly progressing muscle paralysis. Motoneurons have unique features, essentially a highly polarized, lengthy architecture of axons, posing a considerable challenge for maintaining long-range trafficking routes for organelles, cargo, mRNA and secretion with a high energy effort to serve crucial neuronal functions. Impaired intracellular pathways implicated in ALS pathology comprise RNA metabolism, cytoplasmic protein aggregation, cytoskeletal integrity for organelle trafficking and maintenance of mitochondrial morphology and function, cumulatively leading to neurodegeneration. Current drug treatments only have marginal effects on survival, thereby calling for alternative ALS therapies. Exposure to magnetic fields, e.g., transcranial magnetic stimulations (TMS) on the central nervous system (CNS), has been broadly explored over the past 20 years to investigate and improve physical and mental activities through stimulated excitability as well as neuronal plasticity. However, studies of magnetic treatments on the peripheral nervous system are still scarce. Thus, we investigated the therapeutic potential of low frequency alternating current magnetic fields on cultured spinal motoneurons derived from induced pluripotent stem cells of FUS-ALS patients and healthy persons. We report a remarkable restoration induced by magnetic stimulation on axonal trafficking of mitochondria and lysosomes and axonal regenerative sprouting after axotomy in FUS-ALS in vitro without obvious harmful effects on diseased and healthy neurons. These beneficial effects seem to derive from improved microtubule integrity. Thus, our study suggests the therapeutic potential of magnetic stimulations in ALS, which awaits further exploration and validation in future long-term in vivo studies.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-37050


Roadmap for focused ion beam technologies

Höflich, K.; Hobler, G.; Allen, F. I.; Wirtz, T.; Rius, G.; Krasheninnikov, A.; Schmidt, M.; Utke, I.; Klingner, N.; Osenberg, M.; McElwee-White, L.; Córdoba, R.; Djurabekova, F.; Manke, I.; Moll, P.; Manoccio, M.; de Teresa, J. M.; Bischoff, L.; Michler, J.; de Castro, O.; Delobbe, A.; Dunne, P.; Dobrovolskiy, O. V.; Freese, N.; Gölzhäuser, A.; Mazarov, P.; Koelle, D.; Möller, W.; Pérez-Murano, F.; Philipp, P.; Vollnhals, F.; Hlawacek, G.

Abstract

The focused ion beam (FIB) is a powerful tool for fabrication, modification, and characterization of materials down to the nanoscale. Starting with the gallium FIB, which was originally intended for photomask repair in the semiconductor industry, there are now many different types of FIB that are commercially available. These instruments use a range of ion species and are applied broadly in materials science, physics, chemistry, biology, medicine, and even archaeology. The goal of this roadmap is to provide an overview of FIB instrumentation, theory, techniques, and applications. By viewing FIB developments through the lens of various research communities, we aim to identify future pathways for ion source and instrumentation development, as well as emerging applications and opportunities for improved understanding of the complex interplay of ion–solid interactions. We intend to provide a guide for all scientists in the field that identifies common research interest and will support future fruitful interactions connecting tool development, experiment, and theory. While a comprehensive overview of the field is sought, it is not possible to cover all research related to FIB technologies in detail. We give examples of specific projects within the broader context, referencing original works and previous review articles throughout.

Keywords: Focused Ion Beams

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Related publications

  • Open Access Logo Applied Physics Reviews 10(2023)4, 041311
    DOI: 10.1063/5.0162597
    arXiv: 2305.19631
    Cited 8 times in Scopus
  • Poster
    Eu-F-N workshop, 07.-09.06.2023, Zürich, Schweiz
  • Poster
    FIT4NANO workshop, 17.-19.07.2023, Lisbon, Portugal
  • Poster
    AVS69, 05.-10.11.2023, Portland, USA

Permalink: https://www.hzdr.de/publications/Publ-37049


Three-dimensional acoustic monitoring of laser-accelerated protons in the focus of a pulsed-power solenoid lens

Gerlach, S.; Balling, F.; Schmidt, A. K.; Brack, F.-E.; Kroll, F.; Metzkes-Ng, J.; Reimold, M.; Schramm, U.; Speicher, M.; Zeil, K.; Parodi, K.; Schreiber, J.

Abstract

The acoustic pulse emitted from the Bragg peak of a laser-accelerated proton bunch focused into water has recently enabled the reconstruction of the bunch energy distribution. By adding three ultrasonic transducers and implementing a fast data analysis of the filtered raw signals, I-BEAT (Ion-Bunch Energy Acoustic Tracing) 3D now provides the mean bunch energy and absolute lateral bunch position in real-time and for individual bunches. Relative changes in energy spread and lateral bunch size can also be monitored. Our experiments at DRACO with proton bunch energies between 10 and 30 MeV reveal sub-MeV and sub-mm resolution. In addition to this 3D bunch information, the signal strength correlates also with the absolute bunch particle number.

Keywords: DRACO; laser ion acceleration; ALBUS; high-field magnets; beamline; TNSA; detector; ionoaccoustics; ion diagnostics

Involved research facilities

  • Draco

Permalink: https://www.hzdr.de/publications/Publ-37048


Laser‑driven low energy electron beams for single‑shot ultra‑fast probing of meso‑scale materials and warm dense matter

Falk, K.; Smid, M.; Boháček, K.; Chaulagain, U.; Gu, Y.; Pan, X.; Perez-Martin, P.; Krůs, M.; Kozlová, M.

Abstract

Laser wakefield acceleration has proven to be an excellent source of electrons and X‑rays suitable
for ultra‑fast probing of matter. These novel beams have demonstrated unprecedented spatial and
temporal resolution allowing for new discoveries in material science and plasma physics. In particular,
the study of dynamic processes such as non‑thermal melt and lattice changes on femtosecond
time‑scales have paved a way to completely new scientific horizons. Here, we demonstrate the first
single‑shot electron radiography measurement using an femtosecond electron source based on the
downramp‑density gradient laser‑wakefield‑acceleration with the use of a compact Ti:sapphire laser. A
quasi‑monoenergetic electron beam with mean energy of 1.9 ± 0.4 MeV and charge 77 ± 47 pC per shot
was generated by the laser incident onto a gas target and collimated using a two ring‑magnet beam
path. High quality electron radiography of solid objects with spatial resolution better than 150 μm was
demonstrated. Further developments of this scheme have the potential to obtain single‑shot ultrafast
electron diffraction from dynamic lattices. This scheme poses a great promise for smaller scale
university laboratories and facilities for efficient single‑shot probing of warm dense matter, medical
imaging and the study of dynamic processes in matter with broad application to inertial confinement
fusion and meso‑scale materials (mg g/cm2).

Permalink: https://www.hzdr.de/publications/Publ-37046


Reconstructing raw tomography data

Gernhardt, F. P. D.

Abstract

A Snakemake worfklow for tomographically reconstructing raw data using tomopy.

Keywords: workflow; snakemake; tomography; reconstruction

Permalink: https://www.hzdr.de/publications/Publ-37045


Non-local cascade failures and synchronization dynamics on power grids

Ódor, G.; Deng, S.; Hartmann, B.; Kelling, J.

Abstract

Dynamical simulation of the cascade failures on the EU, USA and Hungarian [1] high-voltage
power grids has been done via solving the second-order Kuramoto equation. We show that
synchronization transition happens by increasing the global coupling parameter K with metastable states depending on the initial conditions so that hysteresis loops occur. We provide
analytic results for the time dependence of frequency spread in the large K approximation
and by comparing it with numerics of d = 2, 3 lattices [2], we find agreement in the case of
ordered initial conditions. However, different power-law (PL) tails occur, when the fluctuations
are strong. After thermalizing the systems we allow a single line cut failure and follow the
subsequent overloads with respect to threshold values T . The PDFs p(Nf ) of the cascade failures
exhibit PL tails near the synchronization transition point Kc. Below Kc we find signatures of T -
dependent PL-s, caused by frustrated synchronization, reminiscent of Griffiths effects [3]. Here
we also observe stability growth following blackout cascades, similar to intentional islanding,
but for K > Kc this does not happen. For T < Tc , bumps appear in the PDFs with large mean
values, known as “dragon king” blackout events. We also analyze the delaying/stabilizing effects
of instantaneous feedback or increased dissipation and show how local synchronization behaves
on geographic maps. We demonstrate the occurrence of non-local cascade failure events at the
weak points of the networks.

[1] G. Ódor and B. Hartmann, Entropy 22 (2020) 666.
[2] G. Ódor and S. Deng, Entropy 25 (2023) 164.
[3] G. Ódor, S. Deng, B. Hartmann and J. Kelling, Phys. Rev. E 106 (2022) 034311.

Keywords: power grid; synchronization; failure cascade; Kuramoto model

  • Lecture (Conference)
    48th Conference of the Middle European Cooperation in Statistical Physics (MECO 48), 22.-26.05.2023, Stará Lesná, Slovakia

Permalink: https://www.hzdr.de/publications/Publ-37044


Heterogeneity of the European grids: edge weight, community structure and structural improvements

Hartmann, B.; Deng, S.; Papp, I.; Benedek, K.; Ódor, G.; Kelling, J.

Abstract

Making a given high-voltage power grid more stable and reliable has become a relevant question,
especially when considering the current energetic situation or future development plans to
augment and interconnect the existing network with renewable energy sources. Understanding
the behavior and identifying the critical nodes and links of the network constructed from the
power grid data, give us insight into possible ways to optimize its stability.
We investigate the European high-voltage power grid by not only considering the actual
connections between the nodes but also calculating the edge admittances and weights based on
the 2016 SciGRID project data. We perform community detection analysis and show the level
of synchronization on the 2016 European HV power grids, by solving the set of swing equations.
By investigating these synchronization levels and communities, we identify critical nodes and
links that play a key role in power transmission between different power regions and propose
two ways to improve the synchronization level in the network.

[1] Ódor, Géza and Deng, Shengfeng and Hartmann, Bálint and Benedek, Kristóf and Kelling, Jeffrey,
Heterogeneity of the European grids: nodal behaviour, edge weight, frequency analysis, to be
published.
[2] Ódor, Géza and Deng, Shengfeng and Hartmann, Bálint and Kelling, Jeffrey, Phys. Rev. E, 106,
(2022), 3.

Keywords: power gird; synchronisaton; Kuramoto model

  • Open Access Logo Poster
    48th Conference of the Middle European Cooperation in Statistical Physics (MECO 48), 22.-26.05.2023, Stará Lesná, Slovakia
  • Open Access Logo Lecture (Conference)
    GPU Day, 15.-16.05.2023, Budapest, Hunguary

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Permalink: https://www.hzdr.de/publications/Publ-37043


Synchronization and criticality on connectome graphs

Ódor, G.; Papp, I.; Deng, S.; Kelling, J.

Abstract

The criticality hypothesis for neural systems proposes that optimal information processing, sensitivity, and memory capacity occur near criticality. We investigate the synchronization transition of the Shinomoto-Kuramoto (SK) model on fruit-fly and human connectomes, showing
nontrivial critical behavior with continuously changing exponents, frustrated synchronization,
and chimera states in the resting state [1, 2, 3]. By numerical solution, we determine the
crackling noise durations with and without thermal noise, and show extended non-universal
scaling tails characterized by the exponent 2 < τ < 2.8, in contrast with the Hopf transition
of the Kuramoto model, without the force τ = 3.1(1). Comparing the phase and frequency

[1] G. Odor and J. Kelling, Critical synchronization dynamics of the Kuramoto model on connectome
and small world graphs, Scientific Reports 9 (2019) 19621.
[2] G. Odor, J. Kelling, G. Deco,The effect of noise on the synchronization dynamics of the Kuramoto
model on a large human connectome graph, Neurocomputing, 461 (2021) 696-704.
[3] Geza Odor, Gustavo Deco and Jeffrey Kelling,ifferences in the critical dynamics underlying the
human and fruit-fly connectome, Phys. Rev. Res. 4 (2022) 023057.
[4] Géza Ódor, István Papp, Shengfeng Deng and Jeffrey Kelling, Synchronization transitions on
connectome graphs with external force, Front. Phys. 11 (2023) 1150246.
order parameters, we find different transition points and fluctuations peaks as in the case of the
Kuramoto model. Using the local order parameter values, we also determine the Hurst (phase)
and β (frequency) exponents and compare them with recent experimental results obtained by
fMRI [4]. Our findings suggest that these exponents are smaller in the excited system than in
the resting state and exhibit module dependence.

Keywords: huma brain; synchronization; Kuramoto model

  • Poster
    48th Conference of the Middle European Cooperation in Statistical Physics (MECO 48), 22.-26.05.2023, Stará Lesná, Slovakia

Permalink: https://www.hzdr.de/publications/Publ-37042


The Rise of a Membrane-Free Alkali Metal-Iodide Battery with a Molten Salt Electrolyte

Lee, J.; Weber, N.

Abstract

Liquid metal electrode batteries are a promising solution for sustainable energy storage due to their low manufacturing costs and high recyclability. However, to improve their viability, they need to operate at lower temperatures, higher voltages, and be membrane-free. In this study, we present a novel membrane-free battery design based on liquid alkali metals and iodide. The battery construction involves a simple assembly process without any solid-state mediums for separating the electrolytes. Despite the unoptimized cell design, the membrane-free A-AI batteries exhibit promising electrochemical performance, including stability for 250 cycles and high current density, implying the possibility of an iodine-concentrated layer forming at the bottom of the cell. These findings demonstrate the potential of membrane-free A-AI batteries as a cost-effective and eco-friendly energy storage solution.

  • Lecture (Conference)
    Europe-Korea Conference on Science and Technology, 14.08.2023, München, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37041


An Infrastructure for Harmonizing Semantics and Structures in Research Data

Steinmeier, L.; Rau, F.

Abstract

One of the main enablers for Interoperability and Reproducibility of scientific research data could be the documentation and harmonization of semantics and data structures. We are developing a concept and prototype for an infrastructure and an end-user graph data editor that support these tasks.

Users of the editor will be able to enter their data and metadata in a graph while getting suggestions on existing semantics and structures. If necessary, they can also document their own semantics. The infrastructure provides a platform for publishing and subsequently harmonizing user-made semantics on both a local scale (e.g. within a project) and at a global scale (e.g. within the community of a scientific domain).

We are looking forward to define interfaces to HeliPort.

  • Open Access Logo Lecture (Conference)
    HELIPORT Workshop 2023, 12.-14.06.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37040


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