Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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41449 Publications

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.

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.

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.

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.

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 from 23.05.2024

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.

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 from 30.05.2024

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.

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

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


Roles and Structures in Institutional Research Data Management Systems

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

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.

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

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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.

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.

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.

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.

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.

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

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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.

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

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


No evidence for absence of solar dynamo synchronization

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

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.

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.

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.

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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.

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.

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

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  • 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.

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

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  • 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.

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

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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.

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.

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.

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

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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.

Supplementary information

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


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.

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

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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.

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.

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.

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.

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

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  • 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.

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

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  • 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.

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

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  • 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.

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

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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.

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.

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.

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.

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.

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.

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  • 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.

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

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  • 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

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 in README file in each figure/figureX subfloder with 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 in $HOME/Paraview/ParaView-5.9.1-MPI-Linux-Python3.8-64bit/. 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/Documents/microorigami/src #(or whereever, your chosen parent directory is)
export PATH=$PATH:$HOME/Documents/microorigami/scripts #(or whereever, your chosen parent directory is)
export PATH=$PATH:$HOME/Documents/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, where where 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, are selected raw data related to Figure 10. All other raw data can be reproduced by following the commands in the README text file located in each figX folder, with X=1,2,...,13. After 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".

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.

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.

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  • 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.

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

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


Probing Protein Hydration with Terahertz Spectroscopy

Adams, E.

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.

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.

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  • 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.

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.

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.

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.

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.

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

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  • P-ELBE

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Performance portability for the CMS Reconstruction with Alpaka

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

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

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.

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.

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


Ways for Efficient Decommissioning of Reactor Components and Concrete Shielding

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

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.

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.

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.

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

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  • Draco

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


Dimer Coupling Energies of the Si(001) Surface

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

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.

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.

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.

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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

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

Keywords: Python; Scientific Research Software Architecture

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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.

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.

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

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  • 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.

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.

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.

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.

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.

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.

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.

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.

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 4 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.

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.

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.

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.

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.

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.

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.

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.

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


THEREDA - Thermodynamic Reference Database

Moog, H. C.; Scharge, T.; Seher, H.; Bok, F.; Brendler, V.; Richter, A.; Wissmeier, L.; Henneberg, M.; Altmaier, M.; Gaona, X.; Cevirim-Papaioannou, N.; Freyer, D.; Pannach, M.; Sohr, J.; Voigt, W.

Part of the process to ensure the safety of radioactive waste disposal is the predictive modeling of the solubility of all relevant toxic components in a complex aqueous solution. To ensure the reliability of thermodynamic equilibrium modeling as well as to facilitate the comparison of such calculations done by different institutions it is necessary to create a mutually accepted thermodynamic reference database. To meet this demand several institutions in Germany joined efforts and created THEREDA (Moog et al., 2015).
THEREDA is a suite of programs at the base of which resides a relational databank. Special emphasis is put on thermodynamic data along with suitable Pitzer coefficients which allow for the calculation of solubilities in high-saline solutions. Registered users may either download single thermodynamic data or ready-to-use parameter files for the geochemical speciation codes PHREEQC, Geochemist’s Workbench, CHEMAPP, or TOUGHREACT. Data can also be downloaded in a generic JSON-format to allow for the import into other codes. The database can be accessed via the world wide web: www.thereda.de. Prior to release, the released part of the database is subjected to many tests. Results are compared to results from earlier releases and among the different codes. This is to ensure that by additions of new and modification of existing data no adverse side effects on calculations are caused. Furthermore, our website offers an increasing number of examples for applications, including graphical representation, which can be filtered by components of the calculated system.
References
Moog, H. C., Bok, F., Marquardt, C. M., and Brendler, V.: Disposal of Nuclear Waste in Host Rock formations featuring high-saline solutions - Implementation of a Thermodynamic Reference Database (THEREDA). Appl. Geochem., 55, 72-84, DOI: 10.1016/j.apgeochem.2014.12.016, 2015.

Keywords: THEREDA; Thermodynamic Reference Database; Modeling; Database; Pitzer activity model

  • Poster
    Interdisciplinary Research Symposium on the Safety of Nuclear Disposal Practices safeND 2023, 13.-15.09.2023, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37039


Electronic Density Response of Warm Dense Matter: From Simulations to Experiments

Dornheim, T.

Matter at extreme densities and pressures is ubiquitous throughout our universe and naturally
occurs in astrophysical objects such as giant planet interiors. In addition, such warm dense
matter (WDM) is important for technological applications such as inertial confinement fusion
and the discovery of novel materials. Consequently, WDM is routinely studied in experiments
at large research facilities around the globe, including NIF, LCLS, Omega, and the Sandia Z-
machine in the USA, SACLA in Japan, and the European XFEL in Germany.
In practice, the extreme conditions render the accurate diagnostics of WDM a formidable
challenge as even basic parameters such as the temperature cannot be directly measured, and
have to be inferred indirectly from other observations. In this context, a particularly important
property is given by the electronic density response to an external perturbation, which is
probed for example in X-ray Thomson scattering (XRTS) experiments.
In this talk, I give an overview of a number of recent developments in this field [1].
Specifically, I show how we can use state-of-the-art computational methods such as quantum
Monte Carlo (QMC) [2,3] and density functional theory (DFT) simulations [4] to model a
gamut of electronic density response properties of WDM with unprecedented accuracy. In
addition, I present a new approach that allows one to diagnose the temperature of arbitrary
materials from XRTS experiments in the imaginary-time domain without any simulations or
approximations [5]. Finally, I outline a strategy for future developments based on the close
interplay between simulations and experiments.
Keywords: Warm-dense matter, Inelastic X-ray scattering, Path-integral Monte Carlo,
Density functional theory
References:
[1] T. Dornheim et al., Phys. Plasmas 30, 032705 (2023)
[2] T. Dornheim, J. Vorberger, and M. Bonitz, PRL 125, 085001 (2020)
[3] M. Böhme, Zh. Moldabekov, J. Vorberger, and T. Dornheim, PRL 129, 066402 (2022)
[4] Zh. Moldabekov et al., J. Chem. Theory. Comput. 19, 1286-1299 (2023)
[5] T. Dornheim et al., Nature Comm. 13, 7911 (2022)

  • Lecture (others)
    Seminar at Los Alamos National Laboratory, 30.05.2023, Los Alamos, USA

Permalink: https://www.hzdr.de/publications/Publ-37038


Accurate Temperature Diagnostics for Warm Dense Matter

Dornheim, T.

The experimental investigation of matter under extreme densities and temperatures, as in astrophysical objects and nuclear fusion applications, constitutes one of the most active frontiers at the interface of material science, plasma physics, and engineering. The central obstacle is given by the rigorous interpretation of the experimental results, as even the diagnosis of basic parameters like the temperature T is rendered difficult at these extreme conditions. Here, we present a simple, approximation-free method to extract the temperature of arbitrarily complex materials in thermal equilibrium from X-ray Thomson scattering experiments, without the need for any simulations or an explicit deconvolution [1,2]. Our paradigm can be readily implemented at modern facilities and corresponding experiments will have a profound impact on our understanding of warm dense matter and beyond, and open up a variety of appealing possibilities in the context of thermonuclear fusion, laboratory astrophysics, and related disciplines.

  • Lecture (Conference)
    ICOPS 2023, 22.05.2023, Santa Fe, USA

Permalink: https://www.hzdr.de/publications/Publ-37037


Estimation of neutron fluence distribution within German PWR components for decommissioning studies

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

By the mid of 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 tasks in preparation for the dismantling is to acquire knowledge of the activation distribution within the reactor components. The activation levels depend on the neutron fluence rate within the reactor. Therefore, to achieve this task, a 3D detailed Monte Carlo model of a German PWR has been developed to calculate the neutron fluence rate distribution over the reactor geometry. The prediction credibility of the developed model was validated via metal foil-activation measurements carried out in two active PWRs. The results showed that the model is reliable and suitable for evaluating the neutron radiation field for the following activation calculations. This paper presents the Monte Carlo model and describes the calculations and measurement procedures.

Keywords: German PWR; Decommissioning; Neutron fluence rate; Activation; Monte Carlo; Metal foil-activation measurements

  • Poster
    The Seventeenth International Symposium on Reactor Dosimetry (ISRD-17), 21.-26.05.2023, Lausanne, Switzerland
  • Contribution to proceedings
    The Seventeenth International Symposium on Reactor Dosimetry (ISRD-17), 21.-26.05.2023, Lausanne, Switzerland

Permalink: https://www.hzdr.de/publications/Publ-37035


Production of ⁷⁶Br at the cyclotron Cyclone 18/9

Franke, K.; Mansel, A.; Schöngart, J.

Positron emission tomography (PET) is an excellent tool for transport studies in geological matrices, applied in the risk assessment of future repositories of radioactive waste. Different tracers are required for these studies mimicking inert transport (conservative tracers) and adsorption/desorption phenomena (reactive tracers). Halides are promising candidates as conservative tracers in these experiments. Here, ¹⁸F and ¹²⁴I are well-established tracers. Unfortunately, the interaction of fluorine with calcium minerals and the complex oxidation behavior of iodine limit their use. In this context, ⁷⁶Br is an alternative candidate as conservative tracer. We established the target preparation, irradiation and processing and measured the spatial resolution in PET with a phantom for geological samples.

Keywords: ⁷⁶Br; cyclotron; target processing; dry distillation; positron emission tomography

  • Lecture (Conference)
    15th Workshop of the European Cyclotron Network (CYCLEUR), 22.-23.06.2023, Bucureşti, România

Permalink: https://www.hzdr.de/publications/Publ-37034


Message from the Guest Editor of the 18th Multiphase Flow Conference Special Issue

Lucas, D.

Selected contributions of the 18th Multiphase Flow Conference at HZDR were published Open Access in a special issue Journal Experimental and Computational Multiphase Flow. In this contribution information on the conference is given.

Keywords: multiphase flow

  • Open Access Logo Abstract in refereed journal
    Experimental and Computational Multiphase Flow 5(2023)4, 331-332
    DOI: 10.1007/s42757-022-0154-6

Permalink: https://www.hzdr.de/publications/Publ-37033


Data publication: Simulation of potential and species distribution in a Li||Bi liquid metal battery using coupled meshes

Duczek, C.; Weber, N.; Godinez-Brizuela, O.; Weier, T.

Solver and simulation data for validation test case

Keywords: OpenFOAM; liquid metal battery; molten salt battery; species transfer

Related publications

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Permalink: https://www.hzdr.de/publications/Publ-37032


Capturing the state-of-knowledge in EURAD knowledge management

Knuuti, T.; Tatomir, A.; Göbel, A.; Franzen, C.; Abbasova, D.; Arnold, T.; Brendler, V.; Fuzik, K.

Knowledge about a wide variety of aspects is fundamental for the safe management and disposal of radioactive waste. This importance of Knowledge Management (KM) is also recognised by EURAD, the European Joint Programme on Radioactive Waste Management (RWM), which brings together over 100 organisations from different countries and backgrounds (Waste Management Organisations, Technical Support Organisations, and Research Entities). This vast resource of expertise and experience feeds into several dedicated EURAD KM programme activities. One of these activities, led by Work Package 11 State-of-Knowledge (WP11 SoK), is capturing experts' views on the current State-of-Knowledge on topics relevant to RWM and making this knowledge accessible through dedicated documents. For this, EURAD has developed the Goals Breakdown Structure (GBS), which provides a framework in which topics are structured thematically, as well as a hierarchy of documents that allows accessing knowledge on different levels of detail (see EURAD Roadmap). To make this knowledge available, EURAD is currently developing a Wiki (i.e., a web-based resource that allows access to knowledge and collaborative interactions) and is drafting a sustainable Knowledge Management System and other supportive KM-IT tools while already feeding the tools with content. This article gives an insight into the general EURAD KM concept, the approaches used, and the results obtained until EURAD' s mid-term, after 2.5 years.

Keywords: Radioactive Waste; Knowledge based systems; Waste Disposal; Knowledge Management

Permalink: https://www.hzdr.de/publications/Publ-37030


Phase imaging of irradiated foils at the OMEGA EP facility using phase-stepping X-ray Talbot-Lau deflectometry

Pérez-Callejo, G.; Bouffetier, V.; Ceurvorst, L.; Goudal, T.; Klein, S. R.; Svyatskiy, D.; Holec, M.; Perez-Martin, P.; Falk, K.; Casner, A.; Weber, T. E.; Kagan, G.; Valdivia, M. P.

Diagnosing the evolution of laser-generated High Energy Density (HED) systems is fundamental to develop a correct understanding of the behavior of matter under extreme conditions. Talbot-Lau interferometry constitutes a promising tool, since it permits simultaneous single-shot X-ray radiography and phase-contrast imaging of dense plasmas. We
present the results of an experiment at OMEGA EP that aims to probe the ablation front of a laser-irradiated foil using a Talbot-Lau X-ray Interferometer. A CH foil was irradiated by a laser of 133 J, 1 ns and probed with 8 keV laserproduced backlighter radiation from Cu foils driven by a short-pulse laser (153 J, 11 ps). The ablation front interferograms
were processed in combination with a set of reference images obtained ex-situ using phase-stepping. We managed to obtain attenuation and phase-shift images of a laser-irradiated foil for electron densities above 1022 cm−3. These results showcase the capabilities of Talbot-Lau x-ray diagnostic methods to diagnose HED laser-generated plasmas through
high-resolution imaging.

Keywords: Talbot-Lau; X-ray interferometry; OMEGA EP; phase contrast imaging; deflectometry

Permalink: https://www.hzdr.de/publications/Publ-37029


Assessment of anthropogenic actinide background levels on HZDR’s research campus next to the ground of the new compact AMS system HAMSTER

Fichter, S.; Hain, K.; Hotchkis, M.; Steier, P.; Wallner, A.

Accelerator Mass Spectrometry (AMS) is an ultra-trace analytical technique capable of measuring radionuclides down to ppq levels (i. e. fg/g) and even below. Thus, AMS is especially competitive to classical radioanalytical techniques, such as α, or γ-spectrometry, for nuclides with half-lives > 10 years. Amongst these radionuclides, actinides and their fission products are of major concern, as they possess a serious health risk to humans due to their radioactivity in combination with relatively long half-lives. These nuclides have been released to the environment by humanity’s extensive use of actinides for civil (e.g. nuclear power plants) and military purposes. Obviously, monitoring these radionuclides is crucial for safety assessments and for understanding their behaviour in the environment.
The new AMS facility HAMSTER (Helmholtz Accelerator Mass Spectrometer Tracing Environmental Radionuclides) at HZDR will be especially dedicated to the analysis of actinides in ultra-trace levels. Due to the long lasting history of the research campus Dresden-Rossendorf as the major site for nuclear research in the former GDR a contamination of the construction site cannot be excluded at least on the ultra-trace level relevant for various AMS applications. Thus, soil samples on HZDR‘s research campus have been collected and analysed regarding their 233/236U, 239/240/241/244Pu and 241Am content and isotopic ratios in order to assess possible contamination of the new accelerator building. Special attention is paid to isotopic signatures deviating from the expected global fallout signal, which may point to additional anthropogenic sources.
Eight surface soil samples next to the future HAMSTER facility have been taken prior to the beginning of the construction. The samples have been processed in the existing chemistry labs on HZDR’s campus and measured at two different AMS facilities (VEGA at ANSTO, and VERA at University of Vienna). The Pu concentrations and 24x/239Pu atomic ratios in the samples agree with values reported for global fallout due to atmospheric weapons tests in the 1950s and 60s.[1,2] The 241Am/241Pu ratios in the samples are also pointing to this origin.
Besides the transuranium elements, different uranium isotopes (i.e. 233U and 236U) have been analysed in the soil samples. Recently, it has been shown that the 233U/236U ratio is extremely sensitive to distinguish between releases from civil nuclear industry and global fallout.[3] interestingly, the measured isotopic ratios are lower than expected for a pure global fallout signature. This may point to an additional source of reactor fuel whose origin has to be analysed with future investigations including fission products like 90Sr, 99Tc, 129I and 135/137Cs, which will also be measurable at HAMSTER.
In summary, the actinide background next to the upcoming AMS facility on HZDR’s research campus mainly relates to global fallout signature with some hints for additional 236U background. Proper blank correction is anyway necessary to get reliable results for ultra-trace analysis of actinides and fission products with the new HAMSTER facility at HZDR.

  • Lecture (Conference)
    10. Radiochemischer Workshop, 13.06.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37028


Development of a chemical separation strategy for Pu, Am and Cm from rare-earth rich geological archives

Fichter, S.; Koll, D.; Wallner, A.

The understanding of the formation of the elements has been an intriguing topic within the last decades. It is now approved that the heaviest naturally occurring elements on earth, the actinides, are produced in the astrophysical r-process. However, the exact site of this process is still debated. Recently, the amount of interstellar 244Pu (T1/2 = 81.3 Myr) in various geological archives like deep-sea ferromanganese crusts and sediments has been investigated by applying highly sensitive accelerator mass spectrometry measurements (AMS).[1,2] Correlation of the influx of 244Pu with 60Fe (T1/2 = 2.6 Myr) which is produced by the weak s-process in massive stars and ejected into the interstellar medium by supernovae could point to a possible origin of the r-process in the universe. To further prove this hypothesis, recent investigations focus on the determination of other long-lived radionuclides which are also produced in the r-process, e.g. 247Cm (T1/2 = 15.6 Myr) and 182Hf (T1/2 = 8.9 Myr). However, the separation of the expected ultra-trace amounts of these nuclides (a few 100 atoms per gram) from huge amounts of matrix and interfering elements represents a major analytical challenge. Thus, this contribution aims to probe existing chemical treatment strategies for the determination of minute amounts of actinides and Hf from various geological archives. The separation method is based on anion exchange for Pu separation and extraction chromatography for Cm and Hf, respectively.[3] The yield of the different elements is monitored by a combination of AMS, γ-counting and ICP-MS measurements. The effective separation strategy of different actinides and Hf from major matrix elements allow for processing multi-gram amounts of different geological samples. This is a prerequisite for the detection of live interstellar 247Cm and 182Hf in geological archives. Furthermore, this adapted method can be used for the analysis of environmental samples regarding their content and isotopic ratio of anthropogenically produced Pu, Am and Cm which holds potential for nuclear safeguards and nuclear forensics studies.

  • Lecture (Conference)
    3rd International Conference on Radioanalytical and Nuclear Chemistry, 09.05.2023, Budapest, Ungarn

Permalink: https://www.hzdr.de/publications/Publ-37027


Scalable and Controllable Synthesis of Pt-Ni Bunched-Nanocages Aerogels as Efficient Electrocatalysts for Oxygen Reduction Reaction

Zheng, Y.; Petersen, A. S.; Wan, H.; Hübner, R.; Zhang, J.; Wang, J.; Qi, H.; Ye, Y.; Liang, C.; Yang, J.; Cui, Z.; Meng, Y.; Zheng, Z.; Rossmeisl, J.; Liu, W.

Developing efficient and stable Pt-based oxygen reduction reaction (ORR) electrocatalysts via both economical and controllable routes is critical for the
practical application of electrochemical energy devices. Herein, a scalable, controllable, and general ambient-O2-involved aqueous-solution cultivating strategy to prepare PtxMy (M = Ni, Fe, Co) bunched-nanocages aerogels (BNCs AG) is demonstrated, based on a newly established high-M-to-Pt-precursor-ratio-and-B-incorporation-facilitated M-rich core and Pt-rich shell hydrogel formation process. The Pt83Ni17 BNCs AG shows prominent ORR performance with a mass activity (MA) of 1.95 A mgPt −1 and specific activity of 3.55 mA cm−2, which are 8.9-times and 9.6-times that of Pt supported on carbon (Pt/C), respectively. Particularly,
the Pt83Ni17 BNCs AG displays greatly enhanced durability (MA 82.6% retention) compared to Pt/C (MA 31.8% retention) after a 20 000-cycles accelerated durability test. Systematic studies including density functional theory calculations uncover that the excellent activity is closely related to the optimized ligand and strain effects with the optimized Ni content in this aerogel; the outstanding durability is endowed by the lowered-down Ni leaching with the optimized Pt/Ni ratio and the inhibited sintering due to its appropriate porosity. This work provides new perspectives on the development of electrocatalysts with both high performance and low cost.

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-37026


Effects of geometry and topology in curvilinear ferro- and antiferromagnets

Makarov, D.

In this presentation, we will cover our recent activities on effects of geometric curvature on magnetic responses of ferro- and antiferromagnetic thin films.

Keywords: curvilinear magnetism; magnetic solitons

Involved research facilities

Related publications

  • Invited lecture (Conferences)
    7th international conference "Nanomagnetism and spintronics" (Sol-SkyMag 2023), 19.-23.06.2023, San Sebastian, Gipuzkoa, Spain

Permalink: https://www.hzdr.de/publications/Publ-37025


Examination of the metabolism of both MCT-imaging PET radioligands [18F]FACH and [18F]FACH-d6 in vitro by means of LC-MS/MS - support for understanding preclinical in vivo data from different species

Ludwig, F.-A.; Wenzel, B.; Gündel, D.; Moldovan, R.-P.; Toussaint, M.; Teodoro, R.; Brust, P.; Deuther-Conrad, W.; Kopka, K.; Sadeghzadeh, M.

Objectives: Positron Emission Tomography (PET) is a non-invasive molecular imaging technique, which continues to find increasing application and further development for diagnosis of a broad range of disorders and dysfunctions. Since their involvement in pathophysiological processes that lead to cancer, for example, monocarboxylate transporters (MCTs) are of interest for the development of new radioligands for PET, such as [18F]FACH [1, 2] and its deuterated isotopologue [18F]FACH-d6. Both candidates have been already examined previously in preclinical PET studies in healthy mice and piglets, also with regard to their biodistribution and metabolic fate [3]. However, the general finding that in piglets both radioligands showed significant lower metabolic stability than in mice left some important unanswered questions, especially those relevant to potential clinical application.
Therefore, this study aimed to further explore the metabolic properties of both radioligands by means of in vitro examinations, which besides discovering species dependency in some respects, might allow predictions for their metabolic stability in humans.
Methods: [18F]FACH, [18F]FACH-d6 as well as their corresponding non-radioactive references were incubated with murine (mouse MLM and rat RLM) and human (HLM) liver microsomes and with pig and human S9 fractions, in presence of NADPH, but also other co-factors (e.g. UDPGA). After collection of samples at defined time points, subsequently prepared samples were investigated by radio-HPLC, UV-HPLC or LC-MS/MS. Obtained data allowed calculation of basic metabolic parameters and identification of metabolites formed in vitro.
Results: [18F]FACH, incubated in presence of NADPH at 37°C for up to 60 min, showed highest stability in MLM (t1/2= 29913 min), whereas lowest stability was found in RLM (t1/2= 201 min). A moderate stability was found for both HLM (t1/2= 948 min) and pig S9 fraction (t1/2= 522 min). However, in a recent head-to-head comparison using S9 fractions only, [18F]FACH showed 38 % unchanged radioligand for pig, but 80 % unchanged radioligand for human after 60 min. The deuterated radioligand [18F]FACH-d6 showed a marginal increase of stability only in S9 fraction from pig (t1/2= 675 min). Species differences were also found regarding in vitro degradation pathways, whereby in the molecule the dialkylamino moiety was affected exclusively. By means of non-radiolabeled FACH and LC-MS/MS measurements, dealkylation of one or both of the alkyl chains was found as the main pathway in MLM and HLM. Moreover, single hydroxylation and, to a lesser extent, direct defluorination occurred. In contrast, in RLM and pig S9 fraction single hydroxylation reactions at one of the alkyl chains were predominant, followed by dealkylation and defluorination-hydroxylation. Furthermore, during analysis by acetonitrile-based gradient RP-HPLC, the use of methanol as an additive enabled a high chromatographic resolution of structurally similar hydroxylated metabolites.
Conclusion: Significant species differences could be demonstrated with regard to metabolic stability of both radioligands, as well as their metabolic pathways. In contrast to other examples from literature, the isotopologue [18F]FACH-d6 did not appear to be more stable than [18F]FACH. In this regard, in particular results from HLM and human S9 fraction indicate that the metabolic stability in human might be considerably higher for [18F]FACH than results from previous preclinical PET studies would suggest. Some final investigations are needed in terms of its ADME properties to prove that [18F]FACH is an appropriate candidate for a first in-human study and subsequent clinical translation.

Acknowledgments: This research was funded by the Alexander von Humboldt Foundation, grant number 7211172142.

References:

[1] Sadeghzadeh, M.; Moldovan, R.-P.; Fischer, S.; Wenzel, B.; Ludwig, F.-A.; Teodoro, R.; Deuther-Conrad, W.; Jonnalagadda, S.; Jonnalagadda, S. K.; Gudelis, E.; Šačkus, A.; Higuchi, K.; Ganapathy, V.; Mereddy, V. R.; Drewes, L. R.; Brust, P. Development and radiosynthesis of the first 18F-labeled inhibitor of monocarboxylate transporters (MCTs). J. Labelled Comp. Radiopharm. 2019, 62, 411–424. DOI: 10.1002/jlcr.3739.
[2] Sadeghzadeh, M.; Moldovan, R.-P.; Teodoro, R.; Brust, P.; Wenzel, B. One-step radiosynthesis of the MCTs imaging agent [18F]FACH by aliphatic 18F-labelling of a methylsulfonate precursor containing an unprotected carboxylic acid group. Sci. Rep. 2019, 9, 18890. DOI: 10.1038/s41598-019-55354-w.
[3] Gündel, D.; Sadeghzadeh, M.; Deuther-Conrad, W.; Wenzel, B.; Cumming, P.; Toussaint, M.; Ludwig, F.-A.; Moldovan, R.-P.; Kranz, M.; Teodoro, R.; Sattler, B.; Sabri, O.; Brust, P. Preclinical Evaluation of [18F]FACH in Healthy Mice and Piglets: An 18F-Labeled Ligand for Imaging of Monocarboxylate Transporters with PET. Int. J. Mol. Sci. 2021, 22. DOI: 10.3390/ijms22041645.

Keywords: MCT; moncarboxylate transporters; PET; metabolism; LC-MS

  • Poster
    Drug Metabolism: Gordon Research Conference - Diversity and Connectivity in Progressing ADME Science: Novel Approaches and Emerging Technologies In Silico, In Vitro and In Vivo, 09.-14.07.2023, Holderness, USA

Permalink: https://www.hzdr.de/publications/Publ-37024


Stretch Evolution of Electronic Coupling of the Thiophenyl Anchoring Group with Gold in Mechanically Controllable Break Junctions

Lokamani, M.; Kilibarda, F.; Günther, F.; Kelling, J.; Strobel, A.; Zahn, P.; Juckeland, G.; Gothlef, K.; Sheer, E.; Gemming, S.; Erbe, A.

The current-voltage characteristics of a single-molecule junction are determined by the electronic coupling Γ between the electronic states of the electrodes and the dominant transport channel(s) of the molecule. Γ is profoundly affected by the choice of the anchoring groups and their binding positions on the tip facets, and the tip-tip separation. In this work, mechanically controllable break junction experiments on the N,N’-Bis(5-ethynylbenzenethiol-salicylidene)ethylenediamine are presented, in particular the stretch evolution of Γ with increasing tip-tip separation. The stretch evolution of Γ is characterized by recurring local maxima and can be related to the deformation of the molecule and sliding of the anchoring group above the tip facets and along the tip edges. A dynamic simulation approach is implemented to model the stretch evolution of Γ, which captures the experimentally observed features remarkably well and establishes a link to the microscopic structure of the single-molecule junction.

Keywords: single level model; high throughput simulations; DFTB; electronic coupling

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Permalink: https://www.hzdr.de/publications/Publ-37023


THEREDA – Recent, present, and future developments

Moog, H. C.; Bok, F.; Gaona, X.; Freyer, D.; Miron, D.; Wissmeier, L.

INTRODUCTION

The thermodynamic reference database THEREDA is maintained within the frame of a collaborative project aiming at the calculation of solubilities in high-saline solutions. The database is designed for applications in the context of the disposal of radioactive waste in rock salt formations and clay formations featuring solutions with a higher ionic strength. The project provides an internally consistent set of data, formatted for the use by several widely used geochemical codes. With the focus on high ionic strength systems, THEREDA complements other database projects focusing on low-saline solutions, such as THERMOCHIMIE or the PSI Chemical Thermodynamic Database. Users can access data and application examples, as well as download parameter files for their own use, from the website www.thereda.de.

RECENT DEVELOPMENTS

New project phase
In 2020, the core project entered its 4th phase scheduled to run until 31st of January 2025. Parallel to the core project, coordinated and supported by it, other projects are running dedicated to the extension of THEREDA in specific fields.

Maintenance
Efforts are constantly taken to facilitate maintenance and future development of THEREDA. This includes databank structure, further development of graphical user interface to promote networking on the database, measures for knowledge preservation, and processes and quality management for future releases.

Data release
In 2022 new data were released. Apart from adding and updating datasets released before this was the first cumulative release where all system data sets were combined into one parameter file for each supported code.
The following elements are part of the present release:

  • actinides and their chemical analogues: Th, U, Np, Pu, Am, Cm & Nd,
  • fission products: Se, Sr, Tc & Cs,
  • matrix elements: Na, K, Mg, Ca, Al, Si - Cl, SO4, CO3, PO4,
  • heavy metals: Pb.

Supported codes
After having abandoned the support for EQ3/6, TOUGH-REACT hast been added to the existing support of PHREEQC, ChemApp and Geochemist’s Workbench.

PRESENT AND FUTURE DEVELOPMENTS

Data release planned in 2023
A new data release is planned for the last quarter of this year. Updates and extensions will include:

  • Zn – Na, K, Mg, Ca – Cl, SO4, CO3 – H2O(l) (also alkaline systems),
  • U(+IV) hydrolysis in NaCl, MgCl2 and CaCl2 systems,
  • Solubility of carbonates up to 100°C,
  • Si, Al – Na, K, Mg, Ca – Cl, SO4, CO3 – H2O(l) (aqueous species only, polythermal, also alkaline systems),
  • Na, K, Mg, Ca – Cl, SO4 – H2O(l) (alkaline systems, T ≤ 40°C),
  • H2S(g), HS- – Na, K, Mg – Cl, SO4 – H2O(l) (partially polythermal),
  • Na, K, Mg, Ca – Cl, SO4, NO3 – H2O(l),
  • molar volumes for selected mineral phases.

Application examples
Altogether 505 application examples were created, on display on our website (www.thereda.de). They demonstrate the capabilities of THEREDA and indicate fields of future improvement. Two application example calculations of the data release planned in 2023 are shown in Figure 1 and Figure 2.
Archiving and assessment of exp. data for the system of oceanic salts
The polythermal dataset is based on the evaluation of about 16,000 solubility data points. Since the beginning of the 4th project phase their bibliographic origin is captured in the databank. Previous application examples are reproduced, or new ones created in the process. At present, binary subsystems are completed and ternary subsystems are in the process of revision. Altogether more than 400 primary data files and more than 100 application examples were created.

ACKNOWLEDGEMENTS

THEREDA is funded by the German “Bundesgesellschaft für Endlagerung (BGE)”, contract number 45181017.

Keywords: THEREDA; Thermodynamic Reference Database; Pitzer activity model; database

  • Lecture (Conference)
    Actinide and Brine Chemistry in a Salt Repository Workshop VII (ABC Salt VII), 15.-16.06.2023, Santa Fe, USA

Permalink: https://www.hzdr.de/publications/Publ-37022


Blind prediction of Kd values from NORM sites using the Smart-Kd approach

Bok, F.

The behavior of naturally occurring radioactive materials (NORM) is often defined using distribution coefficients (Kd) in dispersion calculations. Knowledge of such Kd values is therefore of great importance to protect people and the environment from the effects of radioactive radiation. At the same time, the comprehensive determination of Kd taking into account variable geochemical parameters is difficult, in many cases impossible. The theoretical calculation of Kd values from thermodynamic sorption data using the Smart-Kd approach can help here. Within the context of a blind prediction exercise, the possibilities and limits of the theoretical calculation of Kd values were tested.

Keywords: NORM; Kd; blind prediction; Smart-Kd

  • Invited lecture (Conferences) (Online presentation)
    Workshop of the ALLIANCE Topical Roadmap WG NORM, 06.-7.6.2023, Granada, Spanien

Permalink: https://www.hzdr.de/publications/Publ-37021


Formation of Heterobimetallic Complexes by Addition of d10-Metal Ions to [(Me3P)xM(2-C6F4PPh2)2] (x = 1, 2; M = Ni and Pt): A Synthetic and Computational Study of Metallophilic Interactions

Gericke, R.; Bennett, M. A.; Privér, S.; Bhargava, S.

Treatment of the bis(chelate) complexes trans-[M(κ2-2-C6F4PPh2)2] (trans-1M; M = Ni, Pt) and cis-[Pt(κ2-2-C6F4PPh2)2] (cis-1Pt) with equimolar amounts or excess of PMe3 solution gave complexes of the type [(Me3P)xM(2-C6F4PPh2)2] (x = 2: 2Ma, 2Mb x = 1: 3Ma, 3Mb; M = Ni, Pt). The reactivity of complexes of the type 2M and 3M towards monovalent coinage metal ions (M’ = Cu, Ag, Au) was investigated next to the reaction of 1M towards [AuCl(PMe3)]. Four different complex types [(Me3P)2M(µ-2-C6F4PPh2)2M’Cl] (5MM’; M = Ni, Pt; M’ = Cu, Ag, Au), [(Me3P)M(κ2-2-C6F4PPh2)(µ-2-C6F4PPh2)M’Cl]x (x = 1: 6MM’; M = Pt; M’ = Cu, Au; x = 2: 6PtAg), head-to-tail-[(Me3P)ClM(µ-2-C6F4PPh2)2M’] (7MM’; M = Ni, Pt; M’ = Au) and head-to-head-[(Me3P)ClM(µ-2-C6F4PPh2)2M’] (8MM’; M = Ni, Pt; M’ = Cu, Ag, Au) were observed. Single crystal X-ray analyses of complexes 5-8 reveal short metal-metal separations (2.7124(3) – 3.3287(7) Å) suggestive of attractive metal-metal interactions. Quantum chemical calculations (AIM, ELF, NCI, NBO) gave theoretical support that the interaction characteristics reach from pure attractive non-covalent to electron-shared (covalent) character.

Keywords: heterobimetallic; metallophilic interactions; single-crystal X-ray diffraction; NMR spectroscopy; quantum chemical calculations

Permalink: https://www.hzdr.de/publications/Publ-37020


Pushing the limits of 41Ca AMS with CaF2 targets at DREAMS

Vivo Vilches, C.; Rugel, G.; Lachner, J.; Koll, D.; Stübner, K.; Fichter, S.; Winkler, S.; Wallner, A.

The performance of 41Ca measurements at the 6MV AMS system at HZDR, DREAMS (DREsden AMS) was improved in terms of overall efficiency and suppression of interfering isobar 41K. Mixing CaF2 samples not only with Ag, but also with PbF2 increases the negative ionization efficiency by a factor 3, from 0.15% to 0.45%. This option is dedicated to low level samples because ion source parameters have to be lowered, which increases the measurement time. In general, 41K–suppression factor of the detector is improved from 2 × 10⁴ to 4 × 10⁴ by advances in the analysis of the spectra. With such improvements, a 95%confidence level (C.L.) sensitivity for the 41Ca/40Ca ratio of 2 × 10–15 can be achieved at DREAMS.

Keywords: Accelerator mass spectrometry; 41Ca; Ionization efficiency; Isobar suppression; 41K isobaric interference; Gas ionization chamber

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  • Secondary publication expected from 02.05.2024

Permalink: https://www.hzdr.de/publications/Publ-37019


Determining the preferred directions of magnetisation in cubic crystals using symmetric polynomial inequalities

Samad, F.; Hellwig, O.

For a magnetic material, the easy and hard magnetic axes describe the directions of favourable respectively unfavourable alignment of the magnetisation. In this article, we describe how to determine these axes for cubic magnetic crystals. Usually it is assumed without further reasoning that they coincide with some principal symmetry directions of the crystal [Bozorth, Phys. Rev. 50, 1076–1081 (1936)], which is however invalid in general. In contrast, we present a full and elementary analysis using symmetric polynomial inequalities, which are well suited to the symmetry of the problem.

Keywords: Anisotropy; cubic magnetic anisotropy; symmetric polynomial inequalities; symmetry; cubic crystal

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Permalink: https://www.hzdr.de/publications/Publ-37018


Hydrogenic Spin-Valley States of the Bromine Donor in 2H-MoTe2

Sheina, V.; Lang, G.; Stolyarov, V.; Marchenkov, V.; Naumov, S.; Perevalova, A.; Girard, J.-C.; Rodary, G.; David, C.; Romuald Sop, L.; Pierucci, D.; Ouerghi, A.; Cantin, J.-L.; Leridon, B.; Ghorbani Asl, M.; Krasheninnikov, A.; Aubin, H.

In semiconductors, the identification of doping atomic elements allowing to encode a qubit within spin states is of intense interest for quantum technologies. In transition metal dichalcogenides semiconductors, the strong spin-orbit coupling produces locked spin-valley states with expected long coherence time. Here we study the substitutional Bromine Br_Te dopant in 2H-MoTe2. Electron spin resonance measurements show that this dopant carries a spin with long-lived nanoseconds coherence time. Using scanning tunneling spectroscopy, we find that the hydrogenic wavefunctions associated with the dopant levels have characteristics spatial modulations that result from their hybridization to the Q-valleys of the conduction band. From a Fourier analysis of the conductance maps, we find that the amplitude and phase of the Fourier components change with energy according to the different irreducible representations of the impurity-site point group symmetry. These results demonstrate that a dopant can inherit the locked spin-valley properties of the semiconductor and so exhibit long spin-coherence time.

Keywords: quantum technologies; spin-valley state; doping; MoTe2; scanning tunneling spectroscopy; DFT

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Permalink: https://www.hzdr.de/publications/Publ-37017


Optical rectification and electro-optic sampling in quartz

Balos, V.; Wolf, M.; Kovalev, S.; Sajadi, M.

We report the electro-optic sampling (EOS) response and the terahertz (THz) optical
rectification (OR) of the z-cut α-quartz. Due to its small effective second-order nonlinearity, large
transparency window and hardness, freestanding thin quartz plates can faithfully measure the
waveform of intense THz pulses with MV/cm electric-field strength. We show that both its OR
and EOS responses are broad with extension up to ∼8 THz. Strikingly, the latter responses are
independent of the crystal thickness, a plausible indication of dominant surface contribution to
the total second-order nonlinear susceptibility of quartz at THz frequencies. Our study introduces
the crystalline quartz as a reliable THz electro-optic medium for high field THz detection, and
characterize its emission as a common substrate.

Permalink: https://www.hzdr.de/publications/Publ-37016


Pages: [1.] [2.] [3.] [4.] [5.] [6.] [7.] [8.] [9.] [10.] [11.] [12.] [13.] [14.] [15.] [16.] [17.] [18.] [19.] [20.] [21.] [22.] [23.] [24.] [25.] [26.] [27.] [28.] [29.] [30.] [31.] [32.] [33.] [34.] [35.] [36.] [37.] [38.] [39.] [40.] [41.] [42.] [43.] [44.] [45.] [46.] [47.] [48.] [49.] [50.] [51.] [52.] [53.] [54.] [55.] [56.] [57.] [58.] [59.] [60.] [61.] [62.] [63.] [64.] [65.] [66.] [67.] [68.] [69.] [70.] [71.] [72.] [73.] [74.] [75.] [76.] [77.] [78.] [79.] [80.] [81.] [82.] [83.] [84.] [85.] [86.] [87.] [88.] [89.] [90.] [91.] [92.] [93.] [94.] [95.] [96.] [97.] [98.] [99.] [100.] [101.] [102.] [103.] [104.] [105.] [106.] [107.] [108.] [109.] [110.] [111.] [112.] [113.] [114.] [115.] [116.] [117.] [118.] [119.] [120.] [121.] [122.] [123.] [124.] [125.] [126.] [127.] [128.] [129.] [130.] [131.] [132.] [133.] [134.] [135.] [136.] [137.] [138.] [139.] [140.] [141.] [142.] [143.] [144.] [145.] [146.] [147.] [148.] [149.] [150.] [151.] [152.] [153.] [154.] [155.] [156.] [157.] [158.] [159.] [160.] [161.] [162.] [163.] [164.] [165.] [166.] [167.] [168.] [169.] [170.] [171.] [172.] [173.] [174.] [175.] [176.] [177.] [178.] [179.] [180.] [181.] [182.] [183.] [184.] [185.] [186.] [187.] [188.] [189.] [190.] [191.] [192.] [193.] [194.] [195.] [196.] [197.] [198.] [199.] [200.] [201.] [202.] [203.] [204.] [205.] [206.] [207.] [208.] [209.] [210.] [211.] [212.] [213.] [214.] [215.] [216.] [217.] [218.] [219.] [220.] [221.] [222.] [223.] [224.] [225.] [226.] [227.] [228.] [229.] [230.] [231.] [232.] [233.] [234.] [235.] [236.] [237.] [238.] [239.] [240.] [241.] [242.] [243.] [244.] [245.] [246.] [247.] [248.] [249.] [250.] [251.] [252.] [253.] [254.] [255.] [256.] [257.] [258.] [259.] [260.] [261.] [262.] [263.] [264.] [265.] [266.] [267.] [268.] [269.] [270.] [271.] [272.] [273.] [274.] [275.] [276.] [277.] [278.] [279.] [280.] [281.] [282.] [283.] [284.] [285.] [286.] [287.] [288.] [289.] [290.] [291.] [292.] [293.] [294.] [295.] [296.] [297.] [298.] [299.] [300.] [301.] [302.] [303.] [304.] [305.] [306.] [307.] [308.] [309.] [310.] [311.] [312.] [313.] [314.] [315.] [316.] [317.] [318.] [319.] [320.] [321.] [322.] [323.] [324.] [325.] [326.] [327.] [328.] [329.] [330.] [331.] [332.] [333.] [334.] [335.] [336.] [337.] [338.] [339.] [340.] [341.] [342.] [343.] [344.] [345.] [346.] [347.] [348.] [349.] [350.]