Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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41396 Publications

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
Publ.-Id: 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.

Related publications

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

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

Related publications

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


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
Publ.-Id: 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
Publ.-Id: 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
Publ.-Id: 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
Publ.-Id: 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
Publ.-Id: 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

Related publications

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

Related publications

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

Related publications

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

Related publications

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

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

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

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

  • 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
Publ.-Id: 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.

  • 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
Publ.-Id: 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.

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

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

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

Related publications

  • Open Access Logo Applied Physics Reviews 10(2023)4, 041311
    DOI: 10.1063/5.0162597
    arXiv: 2305.19631
    Cited 2 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
Publ.-Id: 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

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

Downloads

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

  • Open Access Logo High Power Laser Science and Engineering 11(2023), e49
    Online First (2023) DOI: 10.1017/hpl.2023.44

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

Related publications

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

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
Publ.-Id: 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
Publ.-Id: 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

Related publications

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

Related publications

Downloads

  • Secondary publication expected from 02.05.2024

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

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37017
Publ.-Id: 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
Publ.-Id: 37016


Flying Adversarial Patches: Manipulating the Behavior of Deep Learning-based Autonomous Multirotors

Hanfeld, P.; Höhne, M. M.-C.; Bussmann, M.; Hönig, W.

Autonomous flying robots, e.g. multirotors, often rely on a neural network that makes predictions based on a camera image. These deep learning (DL) models can compute surprising results if applied to input images outside the training domain. Adversarial attacks exploit this fault, for example, by computing small images, so-called adversarial patches, that can be placed in the environment to manipulate the neural network's prediction. We introduce flying adversarial patches, where an image is mounted on another flying robot and therefore can be placed anywhere in the field of view of a victim multirotor. For an effective attack, we compare three methods that simultaneously optimize the adversarial patch and its position in the input image. We perform an empirical validation on a publicly available DL model and dataset for autonomous multirotors. Ultimately, our attacking multirotor would be able to gain full control over the motions of the victim multirotor.

Keywords: Adversarial Attacks; Multi-Robot Systems; Security

  • Open Access Logo Contribution to proceedings
    Workshop on Multi-Robot Learning, 29.05.-02.06.2023, London, United Kingdom
    International Conference on Robotics and Automation
    DOI: 10.48550/arXiv.2305.12859

Permalink: https://www.hzdr.de/publications/Publ-37015
Publ.-Id: 37015


Dynamic modeling of the neutronic behavior of pressure wave propagation in the Phenix reactor core by using nodal diffusion code DYN3D

Nikitin, E.; Fridman, E.

This paper presents a methodology for time-dependent neutronic analysis of non-uniform deformations
in Sodium Fast Reactor (SFR) cores using the coordinate transformation method. The
methodology was developed for the 3D nodal diffusion code DYN3D, which uses a regular nodal
mesh for its neutronic solvers. To test the methodology, static and dynamic reactivity variations
induced by a postulated pressure spike in the Phenix reactor leading to dynamic core deformation
were calculated with DYN3D. The time-dependent mechanical core deformations were evaluated
beforehand and provided to this study as CAD geometry snapshots. The validity of the method
was demonstrated by comparing the DYN3D results against a Monte Carlo reference solution.
Static reference calculations were carried out beforehand using the Monte Carlo code Serpent,
with CAD snapshots directly used as geometry inputs. The study achieved a very good agreement
between diffusion calculations using coordinate transformation and the MC calculations using
deformed CAD geometries.

Keywords: SFR; thermal expansion; core deformation; nodal diffusion; DYN3D

Related publications

  • Contribution to proceedings
    The International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2023), 13.-17.08.2023, Niagara Falls, Ontario, Canada
  • Lecture (Conference)
    2023 International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering, M&C 2023, 13.-17.08.2023, Niagara Falls, Canada

Permalink: https://www.hzdr.de/publications/Publ-37014
Publ.-Id: 37014


Influence of EDTA and EGTA on the Eu(III)/Cm(III) speciation in the human digestive system

Friedrich, S.; Kretzschmar, J.; Drobot, B.; Stumpf, T.; Barkleit, A.

In mining and industrial areas involved in lanthanide (Ln) production, both environment and population show increased Ln concentrations. To lower the health risks of these heavy metal ions on the affected persons by decreasing the Ln concentration in the human body, chelation therapy is used as decorporation strategy. Chelation therapy is also an important tool for radiation protection. The aminopolycarboxylic acid diethylenetriaminepentaacetic acid (DTPA) is the only clinical approved decorporation agent against actinides (An). However, DTPA is not equally efficient for all An and can be also toxic at higher concentrations.
Therefore, we comprehensively studied the complexation behaviour of DTPA related compounds such as ethylenediaminetetraacetic acid (EDTA) and ethylene glycol-bis(β-aminoethyl ether)-N,N,N’,N’-tetraacetic acid (EGTA) with trivalent europium and curium by combining spectroscopy and isothermal titration calorimetry. The influence of these ligands on the speciation of Eu(III) in the simulated human digestive system has been determined on a molecular level using time-resolved laser-induced fluorescence spectroscopy (TRLFS). Furthermore, the ligands were successfully synthesised in their deuterated form to perform 2H-NMR spectroscopy to overcome the large 1H-NMR background occurring from organic molecules such as proteins and enzymes in the artificial digestive system. These investigations contribute to an advanced understanding of the molecular processes in chelation therapy and its further development in the future.
This work is funded by the German Federal Ministry of Education and Research (BMBF) under grant number 02NUK057A and is part of the joint project RADEKOR.

Keywords: Speciation; Complexation; Decorporation; Europium; Curium

  • Lecture (Conference)
    7th International Conference on Environmental Radioactivity (ENVIRA 2023), 17.-22.09.2023, Sevilla, España

Permalink: https://www.hzdr.de/publications/Publ-37013
Publ.-Id: 37013


Flow field analysis towards improved predictability of diffusive flux in host rocks for radioactive waste

Fischer, C.; Kulenkampff, J.; Bollermann, T.

The predictive power of numerical approaches for the analysis of flow fields and, e.g., radionuclide migration, depends on the quality of the underlying pore network geometry. Validation of the obtained simulation results can only be performed with a limited number of methods. Positron emission tomography (PET) is a suitable technique that has been established in geomaterial sciences in recent years. The employment of appropriate radiotracers allows the analysis of advective transport and diffusive flux in a variety of complex porous materials.
In addition to the visualization of time-resolved transport patterns, the statistical analysis of transport controlling parameters is currently in the focus of investigations using PET techniques. First, local transport properties can be extracted from single voxels or voxel layers of the transport tomograms. Second, the analysis of spatially correlated data sets, e.g. density data from micro-computed tomography (µCT) analyses, is the focus of interest. The purpose is to statistically compare the range of material heterogeneity with the range of transport heterogeneity and to derive generalizable conclusions.
Using low-permeability potential host rock types for underground radioactive waste repositories as examples, we analyzed the heterogeneity of the flow field at the laboratory scale.1 Reliable predictions of diffusive transport heterogeneity are critical for assessing sealing capacity. We identified diagenetic and sedimentary subfacies components based on the concentration of diagenetic minerals and grain size variability, and quantified their pore size distributions and pore network geometries. The resulting generalized pore network geometries are used in digital rock models to calculate effective diffusivities, using a combined upscaling workflow for transport simulations from nanometer to micrometer scales.2 Diffusion experiments analyzed with PET confirmed the simulation results and provided new insights into the heterogeneity of diffusive flux. We introduced a statistical treatment of the PET and µCT tomographic datasets based on the spatial variability of both PET tracer concentrations and rock density. Targeting a generalized applicability, we present and discuss results on diffusive flux in different lithotypes. The focus of the comparison is on quantitative analysis of propagation heterogeneity and the correlation with data characterizing compositional homogeneity. Here we discuss possibilities of statistical evaluation of data from µCT analysis and their potential for correlation with PET analysis methods.
1. Bollermann, T.; Yuan, T.; Kulenkampff, J.; Stumpf, T.; Fischer, C., Pore network and solute flux pattern analysis towards improved predictability of diffusive transport in argillaceous host rocks. Chemical Geology 2022, 606, 120997.
2. Yuan, T.; Fischer, C., The influence of sedimentary and diagenetic heterogeneity on the radionuclide diffusion in the sandy facies of the Opalinus Clay at the core scale. Applied Geochemistry 2022, 146, 105478.

  • Lecture (Conference)
    Interpore 2023, 22.-25.05.2023, Edinburgh, United Kingdom

Permalink: https://www.hzdr.de/publications/Publ-37012
Publ.-Id: 37012


Composition-Dependent Optical Properties of Cu−Zn−In−Se Colloidal Nanocrystals Synthesized via Cation Exchange

Bora, A.; Lox, J.; Hübner, R.; Weiß, N.; Bahmani Jalali, H.; Di Stasio, F.; Steinbach, C.; Gaponik, N.; Lesnyak, V.

Copper chalcogenide-based nanocrystals (NCs) are a suitable replacement for toxic Cd/Pb chalcogenide-based NCs in a wide range of applications including photovoltaics, optoelectronics, and biological imaging. However, despite rigorous research, direct synthesis approaches of this class of compounds suffer from inhomogeneous size, shape, and composition of the NC ensembles, which is reflected in their broad photoluminescence (PL) bandwidths. A partial cation exchange (CE) strategy, wherein host cations in the initial binary copper chalcogenide are replaced by incoming cations to form ternary/quaternary multicomponent NCs, has been proven to be instrumental in achieving better size, shape, and composition control to this class of
nanomaterials. Additionally, adopting synthetic strategies which help to eliminate inhomogeneities in the NC ensembles can lead to narrower PL bandwidths, as was shown by single-particle studies on I−III−VI2-based semiconductor NCs. In this work, we formulate a two-step colloidal synthesis of Cu−Zn−In−Se (CZISe) NCs via a partial CE pathway. The first step is the synthesis of Cu2−xSe NCs, which serve as a template for the subsequent CE reaction. The second step is the incorporation of the In3+ and Zn2+ guest cations into the synthesized Cu2−xSe NCs via simultaneous injection of both metal precursors, which results in gradient-alloyed CZISe NCs with a Zn-rich surface. The as-synthesized NCs exhibit near-infrared (NIR) PL without an additional shell growth, which is typically required in most of the developed protocols. The photoluminescence quantum yield (PLQY) of these Cu chalcogenide-based NCs reaches 20%. These NCs also exhibit intriguingly narrow PL bands, which challenges the notion of broad PL bands being an inherent property of this class of NCs. Additionally, a variation in the feed ratios of the incoming cations, i.e., In/Zn, results in the variation of the composition of the synthesized NCs. Henceforth, the optical properties of these NCs could be tuned by a simple variation of the composition of the NCs achieved by varying the feed ratios of the incoming cations. Within a narrow size distribution, the PL maxima range from 980 to 1060 nm, depending on the composition of the NCs. Post-synthetic surface modification of the synthesized NCs enabled the replacement of the parent long-chain organic ligands with smaller species, which is essential for their prospective applications requiring efficient charge transport. With PL emission extended into the NIR, the synthesized NCs are suitable for an array of potential applications, most importantly in the area of solar energy harvesting and bioimaging. The large Stokes shift inherent to these materials, their absorption in the solar range, and their NIR PL within the biological window make them suitable candidates.

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37009
Publ.-Id: 37009


Synthesis and In Vitro Biological Evaluation of p-Carborane-based Di-tert-butylphenol Analogs

Braun, S.; Jelača, S.; Laube, M.; George, S.; Hofmann, B.; Lönnecke, P.; Steinhilber, D.; Pietzsch, J.; Mijatović, S.; Maksimović-Ivanić, D.; Hey-Hawkins, E.

Targeting inflammatory mediators and related signaling pathways may offer a rational strategy for the treatment of cancer. The incorporation of metabolically stable, sterically demanding, and hydrophobic carboranes in dual cycloxygenase-2 (COX-2)/5-lipoxygenase (5-LO) inhibitors that are key enzymes in the biosynthesis of eicosanoids is a promising approach. The di-tert-butylphenol derivatives R-830, S-2474, KME-4, and E-5110 represent potent dual COX-2/5-LO inhibitors. The incorporation of p-carborane and further substitution of the p-position resulted in four carborane-based di-tert-butylphenol analogs that show no or weak COX inhibition but high 5-LO inhibitory activities in vitro. Cell viability studies on five human cancer cell lines revealed that the p-carborane analogs R-830-Cb, S-2474-Cb, KME-4-Cb, and E-5110-Cb exhibit lower anticancer activity compared to the related di-tert-butylphenols. Inter-estingly, R-830-Cb did not affect the viability of primary cells and suppressed HCT116 cell pro-liferation more potently than its carbon-based R-830 counterpart. Considering all the ad-vantages of boron cluster incorporation for enhancement of drug biostability, selectivity, and availability of drugs, R-830-Cb can be tested in further mechanistic and in vivo studies.

Keywords: carboranes; inflammation; cyclooxygenases; lipoxygenases; cancer

Permalink: https://www.hzdr.de/publications/Publ-37008
Publ.-Id: 37008


Temperature-driven flexomagnetic effects in thin Cr2O3 films

Pylypovskyi, O.; Makushko, P.; Kosub, T.; Hedrich, N.; Li, J.; Pashkin, O.; Avdoshenko, S.; Hübner, R.; Ganss, F.; Wolf, D.; Lubk, A.; Butterling, M.; Wagner, A.; Wagner, K.; Shields, B. J.; Lehmann, P.; Veremchuk, I.; Faßbender, J.; Maletinsky, P.; Makarov, D.

Antiferromagnetic ordering, being prevalent over ferromagnetic one in nature, is very sensitive to the lattice structure. For example, in the absence of magnetostatics, the stress fields can be responsible for the domain formation in easy-plane antiferromagnets, while the hydrostatic pressure provides a possibility to manipulate the phase transition temperature between magnetically ordered and disordered phases [1]. Phenomena related to the strain gradient being allowed in the majority of magnetic symmetry classes are much less explored [2].Here, we provide a theoretical and experimental evidence of flexomagnetism in the uniaxial room-temperature antiferromagnet Cr2O3 [3]. In the experiment, high-quality Cr2O3 thin films grown on sapphire substrate are considered. Their magnetic state is accessed by a combination of magnetotransport measurements and Nitrogen vacancy (NV) magnetometry, which allows one to address both the uncompensated magnetization at the film surface and the interior of the film. We found a gradual transition from antiferro- to paramagnetic state by thickness with heating, which is substantially enhanced in comparison with bulk Cr2O3. To explain this observation, we provide a systematic analysis of sources of magnetization and symmetry analysis regarding the presence of a sizeable strain gradient along the film thickness. The latter enables (i) the net uniform bulk magnetization along the film thickness, which cannot be directly detected by NV magnetometry, and (ii) distribution of the Neel temperature along the film thickness. The gradual change of the magnetic phase transition temperature along the sample breaks the compensation of antiferromagnetic sublattices. The respective magnetization is proportional to the Neel vector and changes its direction betwen antiferromagnetic domains contributing to the stray fields and being detectable by NV magnetometry. We provide a theoretical description of this strain-gradient-driven effects in thin Cr2O3 films and quantify the respective contribution to the flexomagnetic coefficient to be about 15 μB/nm2 [3]. Our findings provide a platform for further fundamental research of flexomagnetic effects in antiferromagnets and use of the Cr2O3 films for thermally reconfigurable devices.[1] S. Reimers et al., Nat. Comm. 13, 724 (2022); Y. Kota et al, Appl. Phys. Express, 6, 113007 (2013)
[2] E. Eliseev et al., Phys. Rev. B, 84, 174112 (2011)
[3] P. Makushko, T. Kosub, O. Pylypovskyi et al., Nat. Comm. 13, 6745 (2022)

Keywords: flexomagnetism; Cr2O3; strain effects

  • Lecture (Conference)
    CMD30 FisMat 2023, 04.-08.09.2023, Milan, Italy

Permalink: https://www.hzdr.de/publications/Publ-37007
Publ.-Id: 37007


Chiral and anisotropic responses in curved anitferromagnetic spin chains

Pylypovskyi, O.; Borysenko, Y.; Tomilo, A.; Sheka, D.; Makarov, D.

Geometry-driven effects in magnetism arise due to (i) sample boundaries, (ii) non-zero curvature of low-dimensional magnets and (iii) non-trivial sample’s geometry. For ferromagnets, all these directions are under intensive studies for a long time, with the primary driver being shape anisotropy stemming from magnetostatics [1]. Antiferromagnets (AFMs) possess more complex magnetic ordering, with a much less fundamental understanding of the interplay between geometry and magnetic textures.The simplest systems uncovering the specific features of AFM exchange in curvilinear geometries are spin chains, which can be arranged along plane and space curves. The dipolar interaction provides the strong hard-axis shape anisotropy for AFM spin chains. Break of the spatial inversion symmetry by geometry leads to the appearance of the chiral response of Dzyaloshinsksii-Moriya interaction symmetry, which enables geometry-driven helimagnetic phase transition for chains along space curves [2]. The weak easy axis for the Neel vector comes from the exchange-driven anisotropy [2]. The presence of the easy axis and easy-plane anisotropies in total allows to observe the field-driven spin-reorientation transitions with the critical fields proportional to the curvature and a family of the topologically different states in spin-flop phase [3]. Furthermore, localized curvature behaves as the effective pinning potential for non-collinear antiferromagnetic textures [4]. [1] D. Sheka, Appl. Phys. Lett., 118, 230502 (2021); D. Makarov et al. Adv. Mater., 34, 2101758 (2022)
[2] O. Pylypovskyi, D. Kononenko et al, Nano Lett., 20, 8157–8162 (2020)
[3] O. Pylypovskyi et al, App. Phys. Lett., 118, 182405 (2021); Y. Borysenko et al., Phys. Rev. B, 106, 174426 (2022)
[4] K. Yershov, Phys. Rev. B, 105, 064407 (2022)

Keywords: spin chains; curvilinear antiferromagnets

  • Invited lecture (Conferences)
    CMD30 FisMat 2023, 04.-08.09.2023, Milan, Italy

Permalink: https://www.hzdr.de/publications/Publ-37006
Publ.-Id: 37006


Numerical investigation of Ultra-high temperature electrical thermal energy storage system integrated with sCO2 power cycle

Bangalore Mohankumar, M.; Unger, S.; Hampel, U.

An energy storage (ES) system is an economical and reliable technology that plays a predominant role in making the renewable energy sector sustainable. Integration of ES with wind and solar plants provides solution to problem of grid instability caused by to fluctuating power output. The Thermal Energy Storage (TES) system is simple and has low environmental and social impacts compared to other ES technologies like batteries, pumped hydro, compressed air and chemical storage. However, application of a TES at high temperatures is quite unexplored and has a limited deployment globally.
Solid sensible TES (STES) stores excess electricity in form of sensible heat, the solid medium is directly electrical heated or indirectly heated using heat transfer fluids (HTF). In STES systems, no phase change nor chemical reactions involved. Hence, it is simple, easy to maintain and the cost of construction materials is low. The aforesaid advantages make it suitable for high temperature applications provided the solid material selected exhibits higher temperature stability.
In the current study, indirect heating via Heat transfer fluid is considered and various solid mediums at different geometrical patterns are considered. The One-dimensional Model is developed in Matlab for the preliminary study and further optimization will be carried out using numerical analysis in ANSYS CFX.

This study will enable the thermal and economical assessment of SSTES systems and their application in Power to heat to Power systems. The study is focused on the integration of TEs systems into power cycles specifically with supercritical carbon dioxide power cycles.

Keywords: Solid sensible medium; Supercritical CO2; Thermal energy storage; Numerical analysis; 1D model

  • Lecture (Conference)
    Numerical investigation of Ultra-high temperature electrical thermal energy storage system integrated with sCO2 power cycle, 26.-27.09.2023, Siegburg, Germany

Permalink: https://www.hzdr.de/publications/Publ-37004
Publ.-Id: 37004


Status report of the n_TOF facility after the 2nd CERN long shutdown period

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

During the second long shutdown period of the CERN accelerator complex (LS2, 2019-2021), several upgrade activities took place at the n_TOF facility. The most important have been the replacement of the spallation target with a next generation nitrogen-cooled lead target. Additionally, a new experimental area, at a very short distance from the target assembly (the NEAR Station) was established. In this paper, the core commissioning actions of the new installations are described. The improvement in the n_TOF infrastructure was accompanied by several detector development projects. All these upgrade actions are discussed, focusing mostly on the future perspectives of the n_TOF facility. Furthermore, some indicative current and future measurements are briefly reported.

Keywords: CERN n ToF

Permalink: https://www.hzdr.de/publications/Publ-37003
Publ.-Id: 37003


Combining x-ray real and reciprocal space mapping techniques to explore the epitaxial growth of semiconductors

Magalhaes, S.; Salgado Cabaco, J.; Concepcion, O.; Buca, D.; Stachowicz, M.; Oliveira, F.; Cerqueira, M. F.; Lorenz, K.; Alves, E.

In the present work, the importance of determining the strain states of semiconductor compounds with high accuracy is
demonstrated. For the matter in question, new software titled LAPAs, the acronym for LAttice PArameters is presented. The
lattice parameters as well as the chemical composition of Al1−xIn x N and Ge1−xSn x compounds grown on top of GaN- and
Ge- buffered c-Al2O3 and (001) oriented Si substrates, respectively, are calculated via the real space Bond’s method. The
uncertainties in the lattice parameters and composition are derived, compared and discussed with the ones found via x-ray
diffraction reciprocal space mapping. Broad peaks lead to increased centroid uncertainty and are found to constitute up to
99% of the total uncertainty in the lattice parameters. Refraction correction is included in the calculations and found to have
an impact of 0.001 Å in the lattice parameters of both hexagonal and cubic crystallographic systems and below 0.01% in the
quantification of the InN and Sn contents. Although the relaxation degrees of the nitride and tin compounds agree perfectly
between the real and reciprocal-spaces methods, the uncertainty in the latter is found to be ten times higher. The impact of
the findings may be substantial for the development of applications and devices as the intervals found for the lattice match
the condition of Al1−xIn x N grown on GaN templates vary between ∼1.8% (0.1675-0.1859) and 0.04% (0.1708-0.1712) if
derived via the real- and reciprocal spaces methods. © 2023 The Author(s). Published by IOP Publishing Ltd.

Keywords: Bond's method; Chemical composition; Lattice parameters; Uncertainties; Gallium Nitride; III-V Semiconductors

Permalink: https://www.hzdr.de/publications/Publ-37002
Publ.-Id: 37002


Investigation of Autonomous Multi-UAV Systems for Target Detection in Distributed Environment: Current Developments and Open Challenges

Adoni, W. Y. H.; Lorenz, S.; Shaik Fareedh, J.; Gloaguen, R.; Bachmann, M.

Uncrewed aerial vehicles (UAVs), also known as drones, are ubiquitous and their use cases extend today from governmental applications to civil applications such as the agricultural, medical, and transport sectors, etc. In accordance with the requirements in terms of demand, it is possible to carry out various missions involving several types of UAVs as well as various onboard sensors. According to the complexity of the mission, some configurations are required both in terms of hardware and software. This task becomes even more complex when the system is composed of autonomous UAVs that collaborate with each other without the assistance of an operator. Several factors must be considered, such as the complexity of the mission, the types of UAVs, the communication architecture, the routing protocol, the coordination of tasks, and many other factors related to the environment. Unfortunately, although there are many research works that address the use cases of multi-UAV systems, there is a gap in the literature regarding the difficulties involved with the implementation of these systems from scratch. This review article seeks to examine and understand the communication issues related to the implementation from scratch of autonomous multi-UAV systems for collaborative decisions. The manuscript will also provide
a formal definition of the ecosystem of a multi-UAV system, as well as a comparative study of UAV types and related works
that highlight the use cases of multi-UAV systems. In addition to the mathematical modeling of the collaborative target
detection problem in distributed environments, this article establishes a comparative study of communication architectures
and routing protocols in a UAV network. After reading this review paper, readers will benefit from the multicriteria decisionmaking
roadmaps to choose the right architectures and routing protocols adapted for specific missions. The open challenges
and future directions described in this manuscript can be used to understand the current limitations and how to overcome
them to effectively exploit autonomous swarms in future trends.

Keywords: autonomous aerial vehicles; autonomous swarm; collaborative missions; communication architectures; distributed environment; distributed path planning; drones; FANET; multi-UAV systems; RPAS; UAS; UAV; uncrewed aerial vehicles

Permalink: https://www.hzdr.de/publications/Publ-37001
Publ.-Id: 37001


Hydrogen Bubble Size Distribution on Nanostructured Ni Surfaces: Electrochemically Active Surface Area Versus Wettability

Krause, L.; Skibińska, K.; Rox, H.; Baumann, R.; Marzec, M. M.; Yang, X.; Mutschke, G.; Żabiński, P.; Lasagni, A. F.; Eckert, K.

Emerging manufacturing technologies make it possible to design the morphology of electrocatalysts on the nanoscale in order to improve their efficiency in electrolysis processes. The current work investigates the effects of electrode-attached hydrogen bubbles on the performance of electrodes depending on their surface morphology and wettability. Ni-based electrocatalysts with hydrophilic and hydrophobic nanostructures are manufactured by electrodeposition and their surface properties are characterized. Despite a considerably larger electrochemically active surface area, electrochemical analysis reveals that the samples with more pronounced hydrophobic properties perform worse at industrially relevant current densities. High-speed imaging shows significantly larger bubble detachment radii with higher hydrophobicity, meaning that the electrode surface area that is blocked by gas is larger than the area gained by nanostructuring. Furthermore, a slight tendency towards bubble size reduction of 7.5% with an increase in the current density is observed in 1 M KOH.

Keywords: hydrogen evolution; water electrolysis; bubble dynamics; structured electrocatalyst; image analysis

Permalink: https://www.hzdr.de/publications/Publ-37000
Publ.-Id: 37000


FLT3-directed UniCAR T-cell therapy of Acute Myeloid Leukaemia

Peschke, J.; Bergmann, R.; Mehnert, M.; González Soto, K. E.; Rodrigues Loureiro, L. R.; Mitwasi, N.; Kegler, A.; Altmann, H.; Wobus, M.; Máthé, D.; Szigeti, K.; Feldmann, A.; Bornhäuser, M.; Bachmann, M.; Fasslrinner, F.; Arndt, C.

Adaptor chimeric antigen receptor (CAR) T-cell therapy offers solutions for improved safety and antigen escape which represent main obstacles for the clinical translation of CAR T-cell therapy in myeloid malignancies. The adaptor CAR T-cell platform “UniCAR” is currently under early clinical investigation. Recently, first proof-of-concept of a well-tolerated, rapidly switchable, CD123-directed UniCAR T-cell product treating patients with acute myeloid leukaemia (AML) was reported. Relapsed and refractory AML is prone to a high plasticity under therapy pressure targeting one single tumour antigen. Thus, targeting of multiple tumour antigens seems to be required to achieve durable anti-tumour responses, underlining the need to further design alternative AML-specific target modules (TM) for the UniCAR platform. We here present the preclinical development of a novel FMS-like tyrosine kinase 3 (FLT3)-directed UniCAR T-cell therapy, which is highly effective for in vitro killing of both AML cell lines and primary AML samples. Furthermore, we show in vivo functionality in a murine xenograft model. PET analyses further demonstrate a short serum half-life of FLT3 TMs, which will enable a rapid on/off-switch of UniCAR T-cells. Overall, the presented preclinical data encourage the further development and clinical translation of FLT3-specific UniCAR T-cells for the therapy of AML.

Keywords: FLT3; CD135; UniCAR; CAR T-cells; Acute Myeloid Leukaemia

Permalink: https://www.hzdr.de/publications/Publ-36999
Publ.-Id: 36999


Background Studies and Normalization of Signal Events in the Mu2e Experiment

Rachamin, R.; Di Falco, S.; Ferrari, A.; Giusti, V.; Müller, S.; Pronskikh, V.

The Mu2e experiment is currently being constructed at Fermilab to search for the neutrino-less conversion of negative muons into electrons in the field of an aluminum nucleus. The experiment aims at a sensitivity of four orders of magnitude higher than previous related experiments, which implies highly demanding accuracy requirements both in the design and during the operation. To achieve such a goal, two important tasks should be accomplished. First, it is essential to estimate precisely the particle yields and all the backgrounds that could mimic the monoenergetic conversion electron signal. Second, it is necessary to normalize the signal events accurately. The normalization of the signal events is planned to be done using a detector system made of an HPGe detector and a Lanthanum Bromide detector, which will measure the rate of muons stopped on the aluminum target by looking at the emitted characteristic X-and γ-rays of energies up to 1809 keV. Therefore, it is essential to evaluate the detector system's performance before the start of the actual experiment. In this study, the first task was addressed by an extensive campaign of Monte Carlo simulations to investigate the relevant parameters and their impact on the experiment's sensitivity. The second task was handled by taking advantage of the Helmholtz-Zentrum Dresden-Rossendorf pulsed Bremsstrahlung photon beam at the ELBE facility. The detector system was tested at the ELBE facility under timing and background conditions similar to the ones expected at the Mu2e experiment. The study presents and discusses the simulation results and the detector system testing campaign.

Keywords: Mu2e experiment; Charged Lepton Flavor Violation; Muon to Electron conversion; ELBE facility; Monte Carlo

Related publications

  • Lecture (Conference)
    New Frontiers in Lepton Flavor, 15.-17.05.2023, Pisa, Italy
  • Contribution to proceedings
    New Frontiers in Lepton Flavor, 15.-17.05.2023, Pisa, Italy
  • Open Access Logo Journal of Instrumentation 18(2023), C11024
    DOI: 10.1088/1748-0221/18/11/C11024

Permalink: https://www.hzdr.de/publications/Publ-36998
Publ.-Id: 36998


Activation calculations of selected German PWR components using the MCNP-FLUKA codes

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

On April 15, the last German nuclear power plants (NPPs) were 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 presentation will give an overview of the methodology and demonstrate its application through the activation calculations of selected components of a German pressurized water reactor (PWR), which is the most common NPP type in Germany.

Keywords: German PWR; Decommissioning; Neutron fluence; FLUKA; MCNP

  • Lecture (Conference)
    AAA Workshop, 10.05.2023, Garching, Germany

Permalink: https://www.hzdr.de/publications/Publ-36997
Publ.-Id: 36997


Specific Immunotherapeutic Targeting of Glioblastoma using the switchable RevCAR NK-92 Cell System

Abdelfatah Saleh Hassan, H. A.; Mitwasi, N.; Rodrigues Loureiro, L. R.; Arndt, C.; Bachmann, M.; Feldmann, A.

Chimeric antigen receptor (CAR)-expressing immune cells, such as CAR Natural Killer (NK) cells and CAR NK-92 cell lines have shown promising therapeutic potential over the past years against solid tumors. Targeting Glioblastoma (GBM) with conventional CAR therapies is still challenging due to the sophisticated tumor microenvironment, antigen escape, and on-target/off-tumor toxicity. Therefore, our project aims to develop a safer and more flexible adapter CAR NK-92 platform, called the Reverse CAR (RevCAR) NK-92 system, which consists of two components, the RevCAR NK-92 cell expressing an extracellular short peptide epitope and a bispecific Rev Target Module (RevTM) that redirect the RevCAR NK-92 cells to tumor cells. Only upon this cross-linkage, redirected RevCAR NK-92 cells are activated to lyse tumor cells. The fibroblast growth factor-inducible 14 (Fn14) surface receptor is a promising target antigen overexpressed on GBM. Therefore, we have developed Fn14-specific RevTM to specifically redirect RevCAR NK-92 cells against Fn14-expressing GBM cells. Through in vitro and in vivo analyses, we assessed the cytotoxic effect of our system on GBM and showed for the first time that GBM cells were efficiently killed by redirected RevCAR NK-92 cells using the novel Fn14-specific RevTM in picomolar concentration, and that the tumor cell killing was associated with increased IFNγ secretion. Hence, these findings give an insight into the clinical potential of the RevCAR NK-92 system as a safe and specific immunotherapy against glioblastoma.

  • Poster
    International Conference on Lymphocyte Engineering, 12.-14.09.2023, Munich, Germany

Permalink: https://www.hzdr.de/publications/Publ-36996
Publ.-Id: 36996


Specific Targeting of Fn14-expressing glioblastoma using RevCAR NK-92 cell system

Abdelfatah Saleh Hassan, H. A.; Mitwasi, N.; Bachmann, M.; Feldmann, A.

Novel immunotherapeutic approaches such as chimeric antigen receptor (CAR)-expressing immune cells are showing promising results against cancer. Among these are the CAR Natural Killer (NK) cells that can be produced from either established cell lines such as NK-92 or allogenic NK cells, which can attack cancer cells. However, some challenges are encountered, when targeting solid tumors, in general and in particular glioblastoma, including the immunosuppressive tumor microenvironment, the antigen escape, the on-target/off-tumor toxicity and neurotoxicities. In addition to the inability to control the activity of conventional CAR NK cells once they are transferred into the patient in case of toxicities occur. Therefore, we aimed to develop a safer and more tumor-specific CAR NK cell platform called the Reverse CAR (RevCAR) NK-92 system. This system consists of two components, the NK-92 cells expressing RevCARs having an extracellular short peptide epitope incapable of recognizing surface antigens by itself, unless redirected by the other component of the system, which is a bispecific molecule called Rev Target Module (RevTM). The RevTM contains two scFvs, one is targeting the respective E5B9 or E7B6 epitope of the RevCAR NK-92 cells and the other one binds to the tumor associated antigen (TAA) of interest. Only in the presence of the respective RevTM, RevCAR NK cells can be directed towards tumor cells, resulting in tumor lysis. By dosing of the short-living RevTMs, we enabled the control of the RevCAR NK cell activity. Furthermore, the modular character of the RevCAR system provides the flexibility for targeting of different TAAs of interest simply by exchanging RevTMs with different specificities. Out of these TAAs, the fibroblast growth factor-inducible 14 (Fn14) surface receptor and its ligand (tumor necrosis factor-related weak inducer of apoptosis (TWEAK)) have been shown to be upregulated in many solid tumors, like glioblastoma. The activation of TWEAK/Fn14 pathway enhances the proliferation, invasion, and migration of tumor cells, and thus a specific targeting of Fn14 is considered a promising approach in glioblastoma therapy. Therefore, we employed here our RevCAR NK-92 system to specifically target Fn14-expressing glioblastoma cells. Through in vitro and in vivo analyses, we showed for the first time that glioblastoma cells were efficiently killed by redirected RevCAR NK-92 cells using picomolar concentrations of the novel Fn14-specific RevTM which was associated with increased IFNγ secretion. Hence, these findings give an insight into the clinical potential of the RevCAR NK-92 system for a safer, specific and more tailored immunotherapy against glioblastoma.

  • Poster
    Tumor Immunology meets Oncology (TIMO) XVII 2023 Halle, 20.-22.04.2023, Halle, Germany

Permalink: https://www.hzdr.de/publications/Publ-36995
Publ.-Id: 36995


Development of an immune therapeutic approach against SARS-CoV-2

Drewitz, L.; Kegler, A.; Laube, M.; Ziehr, H.; Heine, M.; Moreira-Soto, A.; Kühne, A.; Felix Drexler, J.; Seliger, B.; Arndt, C.; Bergmann, R.; Feldmann, A.; Bachmann, M.

Immunotherapies are already successfully used for cancer treatment. In our lab two modular platform technologies were developed which demonstrated high success against various types of malignant cells: the universal chimeric antigen receptor (UniCAR) system, and the bispecific antibody (bsAb) based UniMAB system. Both approaches have the aim to recruit T cells to kill the malignant cells carrying a tumor associated antigen (TAA) on their surface. In the first case, UniCAR modified T cells are linked via a TAA specific target module (TM) to cancer cells. In the case of the UniMAB system, natural T cells are recruited to cancer cells via a TAA specific TM and a bsAb based effector module (EM) which binds to CD3 of T cells and to an epitope tag of the TM. In both cases, an immune complex is formed leading to T cell activation and tumor cell elimination. Most importantly, the T cell activation is dependent on the cross-linkage of T cells and tumor cells via the TM or TM/EM complex. Thus, T cell activation is steerable which increases the safety of these approaches. With the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) leading
to millions of deaths worldwide, we aimed to apply the UniCAR and UniMAB technology against SARS-CoV-2 and virus infected cells as novel immunotherapeutic treatment approach.
For this purpose, we designed two TMs binding to the receptor binding domain (RBD) of SARS-CoV-2. The first TM is based on a single chain fragment variable (scFv) with specificity for RBD, whereas the second one contains the extracellular domain of the human ACE2 receptor which is the entry receptor of SARS-CoV-2. Both TMs were able to efficiently recruit either UniCAR T cells or, in combination with the EM of the UniMAB system, natural T cells to efficiently kill human cells having the RBD of SARS-CoV-2 on their surface. Remarkably, the ACE2-Mb-TM is additionally able to block RBD/ACE2 interaction and potently neutralizes pseudo- as well as live SARS-CoV-2 which is even more pronounced when variants of concern are tested in these assays instead of the respective wild type. Thus, the ACE2-Mb TM represents a potent therapeutic drug against SARS-CoV-2, as it not only recruits UniCAR T cells and, in combination with the EM, natural T cells, but also neutralizes virus particles.

  • Poster
    Tumor Immunology meets Oncology Halle, 20.-22.04.2023, Halle, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36994
Publ.-Id: 36994


The La-protein as an inducible target for CAR T cell therapy

Bartsch, T.; Arndt, C.; Neuber, C.; Feldmann, A.; Bachmann, M.

The La-protein is a multifunctional abundantly expressed protein in the nucleus of all human cells, where it for example functions as a chaperone for newly synthesized RNA-polymerase III transcripts. Recently, it has been shown that La is overexpressed in malignant cells and can be translocated to the cell surface under certain conditions, e. g. radio- or chemotherapy-induced necrosis, where it becomes a promising, inducible target for so-called “Death Targeting” approaches.
The aim of this study was to investigate whether the La-protein could also be used as an inducible target for CAR T cell therapy. Therefore, three different CAR T cells directed against the La-protein (La-CARs) were developed and tested regarding their potential for “Death Targeting” of tumor cells. For construction of the La-CARs, we selected three different anti-La mAbs (5B9, 7B6 and 312B), which recognize distinct epitopes within the La-protein in a redox-dependent manner. This allowed us to determine, if the redox-state influences the ability of the La-CARs to target cell surface-bound La-protein.
We first examined if La-CARs could eliminate tumor cells that were artificially labeled with wildtype La-protein or its oxidation-resistant triple-cysteine-mutant (TCM). By performing luciferase-based killing assays, we showed, that all La-CARs were specifically activated for lysis of La- or TCM-decorated tumor cells, which also resulted in significant secretion of pro-inflammatory cytokines. Redox-dependent differences of the La-CARs could be observed, whereby the non-redox-dependent 5B9-CAR was activated by La-wt- and TCM-labeled cells, the 7B6-CAR preferably by La-wt-labeled and the 312B-CAR preferably by TCM-labeled tumor cells.
We could further prove that La-release from tumor cells could be induced by treatment with the cytotoxic drug cisplatin and La-CARs could be redirected against remaining tumor-cells after cisplatin treatment. Thereby, the 5B9-CAR, which recognizes La-protein independent of its redox-state, induced highest tumor cell killing after cisplatin treatment.
In summary, we could show that the La-protein is a promising target for CAR T cell therapy. Release of La-protein can be induced by the cytotoxic drug cisplatin, making a combinatorial strategy of chemotherapy and CAR T cell therapy a promising approach for tumor immuno-therapy.

  • Lecture (Conference)
    Tumor Immunology meets Oncology (TIMO) XVII 2023, 20.-22.04.2023, Halle, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36993
Publ.-Id: 36993


Targeting immune checkpoint molecules with RevCAR platform for immunotherapy and modulation of the tumor microenvironment

Crespo, E.; Rodrigues Loureiro, L. R.; Arndt, C.; Schmitz, M.; Bachmann, M.; Feldmann, A.

Chimeric antigen receptors (CARs) are used for redirection of T cells against tumor cells and have demonstrated remarkable therapeutic effects against some hematological cancers. The modular system termed RevCAR can overcome the dangerous side effects associated with conventional CAR T cell therapy, such as cytokine release syndrome. It is composed of RevCAR T cells and a bispecific molecule target module, termed RevTM. This system is highly safe since RevCAR T cell activity can be controlled by RevTM and immediately switched off if side effects are detected. It is also versatile, since the same RevCAR T cell can be directed to different tumor-associated antigens (TAA) simply by adding RevTMs with different specificities. However, to improve the effectiveness in the treatment of solid tumors, the immunosuppressive tumor microenvironment (TME) still needs to be addressed. For this purpose, we have developed novel RevTMs targeting immune checkpoint molecules such as PD-L1, which are often upregulated by cancer cells to escape the immune cells. We have demonstrated that our novel RevTMs can redirect RevCAR T cells to specifically kill cell lines expressing immune checkpoint molecules. In addition to this strategy, the combinatorial targeting of a TAA and an immune checkpoint is very promising strategy to overcome the immunosuppressive microenvironment of solid tumors and thus to improve the treatment outcome.

  • Lecture (Conference)
    Tumor Immunology meets Oncology (TIMO) XVII 2023, 20.-22.04.2023, Halle, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36989
Publ.-Id: 36989


Tomographic analysis of advective flow and diffusive flux toward improved migration predictability in host rocks for radioactive waste

Fischer, C.; Kulenkampff, J.; Cardenas Rivera, M. A.; Zhou, W.; Schöngart, J.

The predictive power of numerical approaches for the analysis of flow fields, e.g. for radionuclide
migration, depends on the quality of the underlying pore network geometry. Validation of the
obtained simulation results can only be performed with a limited number of methods. Positron
emission tomography (PET) is a suitable technique that has been established in geomaterial
sciences in recent years. The use of suitable radiotracers allows the analysis of advective transport
and diffusive flux in a variety of complex porous materials. In addition to the visualization of timeresolved
transport patterns, the statistical analysis of transport controlling parameters is currently
in the focus of investigations using PET techniques.
Using potential host rock types with low permeability for underground radioactive waste
repositories as examples, we have analyzed the heterogeneity of the flow field at laboratory scale.1
Diagenetic and sedimentary components and their pore size distributions and pore network
geometries are responsible for the flow field properties. The resulting generalized pore network
geometries are used in digital rock models to calculate effective diffusivities, using a combined
upscaling workflow for transport simulations from the nanometer to the micrometer scale.2 For
advective transport in fractured crystalline rocks, PET provides evidence for the influence of
fracture wall geometries over a wide range of the length scale. Surface building blocks from nm to
mm size are responsible for the observed changes in breakthrough curve behavior. Finally,
another hot topic is the testing of reactive PET tracers for materials analysis. In addition to the use
of conservative tracers described above, reactive tracers provide insight into the density of
reactive surface sites in complex porous materials.
1Bollermann, T.; Yuan, T.; Kulenkampff, J.; Stumpf, T.; Fischer, C., Pore network and solute flux
pattern analysis towards improved predictability of diffusive transport in argillaceous host rocks.
Chemical Geology 2022, 606, 120997.
2Yuan, T.; Fischer, C., The influence of sedimentary and diagenetic heterogeneity on the
radionuclide diffusion in the sandy facies of the Opalinus Clay at the core scale. Applied
Geochemistry 2022, 146, 105478.
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Permalink: https://www.hzdr.de/publications/Publ-36983
Publ.-Id: 36983


Interaction of domain walls with grain boundaries in uniaxial insulating antiferromagnets

Pylypovskyi, O.; Hedrich, N.; Tomilo, A.; Kosub, T.; Wagner, K.; Hübner, R.; Shields, B.; Sheka, D.; Faßbender, J.; Maletinsky, P.; Makarov, D.

A search for high-speed and low-energy memory devices puts antiferromagnetic thin films at the forefront of spintronic research. Here, we develop a material model of a granular antiferromagnetic thin film with uniaxial anisotropy and provide fundamental insight into the interaction of antiferromagnetic domain walls with grain boundaries. This model is validated on thin films of the antiferromagnetic insulator \ch{Cr2O3}, revealing complex maze-like domain patterns hosting localized nanoscale domains down to 50 nm. We show that the inter-grain magnetic parameters can be estimated based on an analysis of high-resolution images of antiferromagnetic domain patterns examining the domain patterns' self-similarity and the statistical distribution of domain sizes. Having a predictive material model and understanding of the pinning of domain walls on grain boundaries, we put forth design rules to realize granular antiferromagnetic recording media.

Keywords: antiferromagnetism; granular media; spin-lattice simulations; Nitrogen vacancy magnetometry

Permalink: https://www.hzdr.de/publications/Publ-36982
Publ.-Id: 36982


Bioethanol sustainable supply chain design: A multi-attribute bi-objective structure

Kheybari, S.; Davoodi Monfared, M.; Salimirad, A.; Rezaei, J.

To design a bioethanol supply chain, along with the transportation and operational costs, it is vital to consider more factors categorized into three sustainability pillars (i.e. economy, social and environment). In this paper, to develop a mathematical model for bioethanol supply chain (BSC), we propose a two-phase methodology; in the first phase, using a sustainable framework of attributes contributing to the facility location selection in the BSC network, we calculate the sustainability score of alternatives through employing the best-worst method (BWM). Then, considering the results of the multi-attribute step as the parameters of an objective function called the sustainability value function, we develop a bi-objective multi-level bioethanol supply chain model. To solve the proposed model, a Nested bi-objective Optimization Genetic Algorithm (NbOGA) is introduced in this research. Finally, we evaluate the performance of the presented BSC model and the algorithm for a real-world problem. The results show that using the proposed structure, both sustainability attributes and transportation costs are appropriately satisfied in the BSC network.

Keywords: Bioethanol Supply Chain; Bi-objective optimization; Genetic Algorithm; Sustainability index; best-worst method

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  • Secondary publication expected from 14.04.2024

Permalink: https://www.hzdr.de/publications/Publ-36980
Publ.-Id: 36980


The Main Results of Structural Materials Research for Safe Long-Term Operation of LWR NPPs from the Viewpoint of Dissemination Activities

Shugailo, O.; Kolluri, M.; Gillemot, F.; Ulbricht, A.; Brumovsky, M.

One of the main points of any project implementation is the dissemination of the obtained results among the nuclear
community, young researchers, public, stakeholders, etc. Communication and dissemination activities are considered as high-priority elements in European collaborative research projects. The article briefly presents EUROATOM project “STRUctructural MATerials Research for Safe Long-Term Operation of LWR NPPs” (STRUMAT-LTO), that was started in September 2020, describes its goals, main steps, expected outputs, approaches used for dissemination and communication activities and brief status update on interim results after 2 years’ implementation. In general, the deployment of the STRUMAT-LTO project was dedicated to studying synergetic effects of Ni-Mn-Si on RPV embrittlement at high fluences by exploiting unique RPV model steels irradiated in LYRA-10 irradiation experiment and assessing the Embrittlement Trend Curves for LTO and Master curve approach for LTO. All these activities are aimed at finding a solution to justify safe LTO until 80 years of operation.

Keywords: ageing management; dissemination activity; embrittlement; fluence; long-term operation; LYRA-10; reactor pressure vessel; STRUMAT-LTO; synergetic effects

Permalink: https://www.hzdr.de/publications/Publ-36979
Publ.-Id: 36979


Data publication: Design and Biological Evaluation of Small-Molecule PET-Tracers for Imaging of Programmed Death Ligand 1

Krutzek, F.; Donat, C.; Ullrich, M.; Zarschler, K.; Ludik, M.-C.; Feldmann, A.; Rodrigues Loureiro, L. R.; Kopka, K.; Stadlbauer, S.

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

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Permalink: https://www.hzdr.de/publications/Publ-36978
Publ.-Id: 36978


Design and Biological Evaluation of Small-Molecule PET-Tracers for Imaging of Programmed Death Ligand 1

Krutzek, F.; Donat, C.; Ullrich, M.; Zarschler, K.; Ludik, M.-C.; Feldmann, A.; Rodrigues Loureiro, L. R.; Kopka, K.; Stadlbauer, S.

Noninvasive molecular imaging of the PD-1/PD-L1 immune checkpoint is of high clinical relevance for patient stratification and therapy monitoring in cancer patients. Here we report nine small-molecule PD-L1 radiotracers with solubilizing sulfonic acids and a linker–chelator system, designed by molecular docking experiments and synthesized according to a new, convergent synthetic strategy. Binding affinities were determined both in cellular saturation and real-time binding assay (LigandTracer), revealing dissociation constants in the single digit nanomolar range. Incubation in human serum and liver microsomes proved in vitro stability of these compounds. Small animal PET/CT imaging, in mice bearing PD-L1 overexpressing and PD-L1 negative tumors, showed moderate to low uptake. All compounds were cleared primarily through the hepatobiliary excretion route and showed a long circulation time. The latter was attributed to strong blood albumin binding effects, discovered during our binding experiments. Taken together, these compounds are a promising starting point for further development of a new class of PD-L1 targeting radiotracers.

Related publications

Permalink: https://www.hzdr.de/publications/Publ-36977
Publ.-Id: 36977


Resolution-Adaptive Modelling in Nuclear Safety: Free Surfaces and Bubbles

Tekavčič, M.; Meller, R.; Krull, B.; Schlegel, F.

Process engineering and energy production systems often feature gas-liquid flows with coexisting two-phase flow regimes and a broad range of interfacial and turbulent scales. Suitable simulation methods can be found for each particular morphology, such as Volume-of-Fluid for larger, resolvable and continuous features of stratified flows, and the two-fluid model for unresolved dispersed bubbles or droplets. A morphology-adaptive multifield two-fluid model (MultiMorph) presented here is developed based on the OpenFOAM Foundation Release, with the aim to handle different coexisting dispersed and continuous flow structures for a wide range of spatial resolutions within a common computational tool.

The present work highlights specifically the following aspects of the model: a resolution-adaptive momentum transfer for under-resolved flow structures on coarse meshes, interface turbulence damping in strong shear flow near a gas-liquid surface with high density ratios between the phases, and morphology transfer models. This enables both transitions, disintegration and accumulation, between dispersed and continuous phase morphologies of the same fluid. Application of the MultiMorph model is presented on the following selected set of safety related test cases: a stratified counter-current flow case with partial flow reversal and liquid waves, and a plunging jet case, with entrainment of gas bubbles. Results are evaluated with measurements from the corresponding experiments.

  • Poster
    International Conference Nuclear Energy for New Europe (NENE), 11.-14.09.2023, Portorož, Slovenia

Permalink: https://www.hzdr.de/publications/Publ-36976
Publ.-Id: 36976


Development of the High-Affinity Carborane-Based Cannabinoid Receptor Type 2 PET Ligand [18F]LUZ5-d8

Ueberham, L.; Gündel, D.; Kellert, M.; Deuther-Conrad, W.; Ludwig, F.-A.; Lönnecke, P.; Kazimir, A.; Kopka, K.; Brust, P.; Moldovan, R.-P.; Hey-Hawkins, E.

The development of cannabinoid receptor type 2 (CB2R) radioligands for positron emission tomography (PET) imaging was intensively explored. To overcome the low metabolic stability and simultaneously increase the binding affinity of known CB2R radioligands, a carborane moiety was used as a bioisostere. Here we report the synthesis and characterization of carboranebased 1,8-naphthyridinones and thiazoles as novel CB2R ligands. All tested compounds showed low nanomolar CB2R affinity, with (Z)-N-[3-(4-fluorobutyl)-4,5-dimethylthiazole-2(3H)-ylidene]-(1,7-dicarba-closo-dodecaboranyl)-carboxamide (LUZ5) exhibiting the highest affinity (0.8 nM). Compound [18F]LUZ5-d8 was obtained with an automated radiosynthesizer in high radiochemical yield and purity. In vivo evaluation revealed the improved metabolic stability of [18F]LUZ5-d8 compared to that of [18F]JHU94620. PET experiments in rats revealed high uptake in spleen and low uptake in brain. Thus, the introduction of a carborane moiety is an appropriate tool for modifying literature-known CB2R ligands and gaining access to a new class of high-affinity CB2R ligands, while the in vivo pharmacology still needs to be addressed.

Keywords: cannabinoid receptor; ligand; protein binding; animal; brain; diagnostic imaging; metabolism; positron emission tomography; procedures; rat; Animals; Brain; Ligands; Positron-Emission Tomography; Protein Binding; Rats; Receptors; Cannabinoid

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Permalink: https://www.hzdr.de/publications/Publ-36975
Publ.-Id: 36975


Experimental investigations and Simulations of Dark Current in ELBE SRF gun-II

Xiang, R.; Arnold, A.; Gatzmaga, S.; Ma, S.; Michel, P.; Murcek, P.; Niemczyk, R.; Ryzhov, A.; Schaber, J.; Teichert, J.

In the high gradient rf photoinjectors, dark current is the “unwanted beam” not produced by the cathode drive laser. It is a part of field emission from the cavity and photocathode, which is accelerated through the gun. Dark current can cause beam loss, increase the risk of damage to accelerator components, and create additional background for beam users. Furthermore, during operation of the ELBE srf gun, the dark current has been found to correlate with the photocathode QE and life time. Therefore, understanding the sources as well as the dynamics of dark current is crucial to machine safety and gun quality.
In this paper we present our experimental investigations of the dark current at the ELBE SRF gun-II. The beam dynamics of the dark current is studied with the ASTRA code, which helps us to track the field electrons starting from the cathode area and from other sources, so that we can understand their different contributions to the dark current.

Keywords: photocathode; SRF gun; Dark current; field emission

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  • Open Access Logo Poster
    14th International Particle Accelerator Conference (IPAC2023), 07.-12.05.2023, Venezia, Italy

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Permalink: https://www.hzdr.de/publications/Publ-36974
Publ.-Id: 36974


Low-emittance SRF photo-Injector phototype cryomodule for the LCLS-II High-Energy upgrade: design and fabrication

Xu, T.; Choi, Y.; Compton, C.; Chang, W.; Du, X.; Greene, D.; Hartung, W.; Kim, S.-H.; Konomi, T.; Miller, S. J.; Morris, D.; Patil, M. S.; Popielarski, L.; Saito, K.; Wei, J.; Yin, Z.; Smedley, J.; Adolphsen, C.; Coy, R.; Ji, F.; Murphy, M.; L, X.; Kelly, M.; Petersen, T.; Piot, P.; Arnold, A.; Gatzmaga, S.; Murcek, P.; Xiang, R.; Teichert, J.; Lewellen, J. W.

The high-energy upgrade of the Linac Coherent Light Source II (LCLS-II-HE) will extend the X-ray energy range up to 20 keV. The goal is to produce low emittance (0.1 mm∙mrad) electron bunches (100 pC/bunch) and accelerate 30 μA beams through the superconducting linac to 8 GeV. A low-frequency superconducting radio-frequency photo-injector (SRF-PI) will be a key aspect of the upgrade. An SRF-PI cryomodule with a 185.7 MHz QuarterWave Resonator (QWR) for operation at a cathode field of 30 MV/m and a cathode system compatible with high quantum efficiency photo-cathodes operating at 55-80 K or 300 K are currently being developed. We report on the design and fabrication status of the SRF-PI cryomodule and cathode system for LCLS-II-HE.

  • Open Access Logo Poster
    14th International Particle Accelerator Conference (IPAC2023), 07.-12.05.2023, Venice, Italy
    DOI: 10.18429/JACoW-IPAC-23-TUPA028
  • Open Access Logo Contribution to proceedings
    14th Int. Particle Acc. Conf. (IPAC2023), 07.-12.05.2023, Venezia, Italy
    Proceedings of the 14th International Particle Accelerator Conference
    DOI: 10.18429/JACoW-IPAC-23-TUPA028

Permalink: https://www.hzdr.de/publications/Publ-36973
Publ.-Id: 36973


Adhesion force measurement and resuspension of glass particles from a wall surface functionalized with well-defined microasperities

Lecrivain, G.; Graebe, K.; Rudolph, M.; Lorenz, P.; Zimmer, K.; Henry, C.; Hampel, U.

The resuspension of microparticles by a turbulent gas flow occurs in many industrial
systems. Industrial surfaces, onto which particles initially adhere, are rarely smooth and
this surface roughness affects their resuspension. Available experimental data on particle
resuspension have been obtained with substrates, whose surfaces are either unaltered or
manually abraded with, for instance, sand blasting. In these experiments, the roughness
elements span a wide size range and are in-homogeneously distributed in space. Surface
functionalization is a modern technique allowing the precise fabrication of a wall surface
with well-characterized microstructures, hence reducing the asperity randomness associated
with conventional abrasion techniques. Taking advantage of surface functionalization, we
present here a new set of reference data, where the wall asperities are represented by a
structured arrangement of micropillars and microcubes. Adhesion force measurements and
particle remaining fraction against gas velocity, at Reynolds number up to 8000, are reported
for one reference and two artificially roughened substrates. Laboratory measurements show
that the microasperities have little to moderate effect on the mean adhesion force and the
threshold velocity, at which half of the 100 μm particles resuspend. The standard deviations
are, however, significantly affected. The presented results will primary contribute to the
improvement of resuspension models, which until now rely on a simplified representation of
the surface roughness elements.

Keywords: Particle resuspension; Turbulent flows; Experiment

  • Lecture (Conference)
    Euromech Colloquium 628 “Complex Particles in Turbulent Flows”, 03.-05.05.2023, Nice, France
  • Poster
    International Congress on Particle Technology, 26.-28.09.2023, Nürnberg, Gremany

Permalink: https://www.hzdr.de/publications/Publ-36972
Publ.-Id: 36972


Designing chiral magnetic responses by tailoring geometry of thin films: curvilinear ferro- and antiferromagnets

Makarov, D.

Extending 2D structures into 3D space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics, superconductivity and magnetism [1,2]. This approach provides means to modify conventional or to launch novel functionalities by tailoring curvature and 3D shape of magnetic thin films and nanowires [2,3]. In this talk, we will address fundamentals of curvature-induced effects in magnetism and discuss realizations of curved low-dimensional architectures and their characterization, which among others resulted in the experimental confirmation of exchange-driven chiral effects [4]. Geometrically curved architectures can support a new chiral symmetry breaking effect: it is essentially non-local and manifests itself even in static spin textures living in curvilinear magnetic nanoshells [5]. The field of curvilinear magnetism was extended towards curvilinear antiferromagnets [6,7], offering a novel material science platform for antiferromagnetic spinorbitronics. It was demonstrated that intrinsically achiral 1D curvilinear antiferromagnets behave as a chiral helimagnet with geometrically tunable DMI, orientation of the Neel vector and the helimagnetic phase transition [6]. Application potential of geometrically curved magnetic thin films is being explored as mechanically reshapeable magnetic field sensors for automotive applications, memory, spin-wave filters, high-speed racetrack memory devices as well as on-skin interactive flexible [8,9] and printed self-healable electronics [10].

[1] P. Gentile et al., Nature Electronics (Review) 5 (2022) 551.
[2] D. Makarov et al., Advanced Materials (Review) 34 (2022) 2101758.
[3] D. Makarov et al., Curvilinear micromagnetism: from fundamentals to applications (Springer, Zurich, 2022). https://link.springer.com/book/10.1007/978-3-031-09086-8
[4] O. Volkov et al., Physical Review Letters 123 (2019) 077201.
[5] D. Sheka et al., Communications Physics 3 (2020) 128.
[6] O. Pylypovskyi et al., Nano Letters 20 (2020) 8157.
[7] O. Pylypovskyi et al., Appl. Phys. Lett. 118 (2021) 182405.
[8] J. Ge et al., Nature Communications 10 (2019) 4405.
[9] G. S. Canon Bermudez et al, Nature Electronics 1 (2018) 589.
[10] R. Xu et al., Nature Communications 13 (2022) 6587.

Keywords: curvilinear magnetism; magnetic solitons

Related publications

  • Invited lecture (Conferences)
    4th Solid-State Science & Research meeting (SCIRES), 28.-30.06.2023, Zagreb, Croatia

Permalink: https://www.hzdr.de/publications/Publ-36971
Publ.-Id: 36971


Magnetic textures: from fundamentals to applications

Makarov, D.

This will be a lecture for students in the frame of the IEEE Summer School in Bari, Italy from 11-16 June 2023.

Keywords: magnetic domain walls; magnetic solitons

Related publications

  • Invited lecture (Conferences)
    IEEE Magnetics Society Summer School 2023, 11.-16.06.2023, Bari, Italy

Permalink: https://www.hzdr.de/publications/Publ-36970
Publ.-Id: 36970


Curvilinear magnetism: from fundamentals to applications

Makarov, D.

The behaviour of any physical system is determined by the order parameter whose distribution is governed by the geometry of the physical space of the object, in particular its dimensionality and curvature. In magnetism, the coupling between geometry (topology) of a ferromagnet and magnetic order parameter brings about novel responses of curved thin films and nanowires [1]. In thin film limit, local curvatures can force a geometry-driven local interactions like Dzyaloshinskii–Moriya interaction (DMI) and anisotropy as well as novel non-local chiral effects. In addition to activities on geometrically curved ferromagnets, there are recent appealing developments for curvilinear antiferromagnets where curvature effects results in the appearance of chiral responses, helimagnetic phase transitions, weak ferromagnetism and hybridisation of spin wave modes. Contrary to planar non-collinear structures, curvilinear design enables 3D architectures, which can revolutionize magnetic devices with respect to size, functionality and speed. At present, 3D-shaped magnetic architectures are explored as spin-wave filters, racetrack memory, artificial magnetoelectric materials, and shapeable magnetoelectronics for human-machine interfaces and soft robotics [2]. These fundamental and application-oriented topics will be covered in the presentation [3].
[1] D. Makarov et al., Adv. Mater. (Review), 34, (2022), 2101758.
[2] G. S. Canon Bermudez et al., Adv. Funct. Mater. (Review), 31, (2021), 2007788.
[3] D. Makarov and D. Sheka (Editors), Curvilinear micromagnetism: from fundamentals to applications (Springer, Zurich, 2022). https://link.springer.com/book/10.1007/978-3-031-09086-8

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

Related publications

  • Invited lecture (Conferences)
    Zakopane School of Physics Breaking Frontiers: Submicron Structures in Physics and Biology, 23.-27.05.2023, Zakopane, Poland

Permalink: https://www.hzdr.de/publications/Publ-36969
Publ.-Id: 36969


What is going on in a laser plasma wakefield accelerator (LPWFA)? - a theoretical perspective on the hybrid concept

Pausch, R.; Bussmann, M.; Assmann, R. W.; Corde, S.; Couperus Cabadağ, J.; Chang, Y.-Y.; Ding, H.; Döpp, A.; Gilljohann, M. F.; Götzfried, J.; Heinemann, T.; Hidding, B.; Karsch, S.; Köhler, A.; Kononenko, O.; Kurz, T.; Martinez De La Ossa, A.; Raj, G.; Schöbel, S.; Steiniger, K.; Schindler, S.; Zarini, O.; Irman, A.; Schramm, U.; Debus, A.

The combination of laser wakefield acceleration (LWFA) with plasma wakefield acceleration (PWFA) provides a miniaturized testbed for the study of PWFA. Since the first experimental implementation of this hybrid concept, various driver generation methods and witness injection have been investigated. Extensive simulation studies accompanied these experiments and provided insights into the complex interplay between the individual stages and the processes occurring within them. This real-world implementation allowed us to revisit and refine the original concepts. Here we present this revised implementation guide for LPWFA.

Derived from these simulation campaigns, we present a theoretical analysis of the processes relevant to LPWFA hybrid accelerators. Requirements and possible methods for generating a driver package in the LWFA stage are discussed, and different laser extraction techniques are compared. The driver evolution in the PWFA stage is studied and the implications for performance limits relevant to current experiments are discussed. Different witness generation methods are also compared in terms of reproducibility and beam quality.

The analysis is based on 3D3V particle-in-cell simulations performed with PIConGPU. Its 3D capability and efficiency allows studying non-rotational effects such as oblique density profiles of shocks and higher laser modes originating from experimental measurements. Their influences are briefly discussed, as well as general requirements on start-to-end simulations.

Keywords: laser plasma accelerator; LWFA; PWFA; LPWFA; PIConGPU; hybrid

  • Poster
    Laser and Plasma Accelerators Workshop 2023, 06.-10.03.2023, Lagos, Portugal

Permalink: https://www.hzdr.de/publications/Publ-36968
Publ.-Id: 36968


Hardware-agnostic Interactive Exascale In situ Visualization of Particle-In-Cell Simulations

Meyer, F.; Hernandez, B.; Pausch, R.; Widera, R.; Groß, D.; Bastrakov, S.; Hübl, A.; Juckeland, G.; Kelling, J.; Leinhauser, M.; Rogers, D.; Schramm, U.; Steiniger, K.; Gumhold, S.; Young, J.; Bussmann, M.; Chandrasekaran, S.; Debus, A.

The volume of data generated by exascale simulations requires scalable tools for analysis and visualization. Due to the relatively low I/O bandwidth of modern HPC systems, it is crucial to work as close as possible with simulated data via in situ approaches. In situ visualization provides insights into simulation data and, with the help of additional interactive analysis tools, can support the scientific discovery process at an early stage. Such in situ visualization tools need to be hardware-independent given the ever-increasing hardware diversity of modern supercomputers. We present a new in situ 3D vector field visualization algorithm for particle-in-cell (PIC) simulations and performance evaluation of the solution developed at large-scale. We create a solution in a hardware-agnostic approach to support high throughput and interactive in situ processing on leadership class computing systems. To that end, we demonstrate performance portability on Summit’s and the Frontier’s pre-exascale testbed at the Oak Ridge Leadership Computing Facility.

Keywords: PIConGPU; ISAAC; HPC; particle-in-cell; in-situ; rendering; live visualization; exascale

  • Contribution to proceedings
    The Platform for Advanced Scientific Computing (PASC) Conference, 26.-28.06.2023, Davos, Schweiz
    Platform for Advanced Scientific Computing Conference (PASC '23): ACM, 979-8-4007-0190-0/23/06
    DOI: 10.1145/3592979.3593408
  • Lecture (Conference)
    The Platform for Advanced Scientific Computing (PASC) Conference, 26.-28.06.2023, Davos, Schweiz

Permalink: https://www.hzdr.de/publications/Publ-36967
Publ.-Id: 36967


Radiofluorination of an anionic, azide-functionalized teroligomer by copper-catalyzed azide-alkyne cycloaddition

Wenzel, B.; Schmid, M.; Teodoro, R.; Moldovan, R.-P.; Lai, T. H.; Mitrach, F.; Kopka, K.; Fischer, B.; Schulz-Siegmund, M.; Brust, P.; Hacker, M. C.

This study describes the synthesis, radiofluorination and purification of an anionic amphiphilic teroligomer developed as stabilizer for siRNA-loaded calcium phosphate nanoparticles (CaP-NP). As the stabilizing amphiphile accumulates on nanoparticle surfaces, the fluorine-18 labeled polymer should enable to track the distribution of the CaP-NP in brain tumors after ap-plication by convection-enhanced delivery. At first, an unmodified teroligomer was synthesized with a number average molecular weight of 4550 ± 20 Da by free radical polymerization of a de-fined composition of methoxy-PEG-monomethacrylate, tetradecyl acrylate and maleic anhy-dride. Subsequent derivatization of anhydrides with azido-TEG-amine provided an azido func-tionalized polymer precursor (o14PEGMA-1) for radiofluorination. The 18F-labeling was accom-plished by copper-catalyzed cycloaddition of o14PEGMA-1 with the diethylene glycol - alkyne substituted heteroaromatic prosthetic group [18F]2 which was synthesized with a radiochemical yield (RCY) of about 38% within 60 min using a radiosynthesis module. The 18F-labeled polymer [18F]fluoro-o14PEGMA-2 was obtained after a short reaction time of 2-3 min by using CuSO4/sodium ascorbate at 90 °C. Purification was performed by solid-phase extraction on an anion-exchange cartridge followed by size-exclusion chromatography to obtain [18F]fluoro-o14PEGMA-2 with a high radiochemical purity and an RCY of about 15%.

Keywords: teroligomer; fluorine-18; 18F-polymer; click reaction; CuAAC; PEG-[18F]FPyKYNE

Permalink: https://www.hzdr.de/publications/Publ-36965
Publ.-Id: 36965


XUV Fluorescence Detection of Laser-Cooled Stored Relativistic Ions

Ueberholz, K.; Bozyk, L.; Bussmann, M.; Eizenhöfer, N.; Hannen, V.; Horst, M.; Kiefer, D.; Kiefer, N.; Klammes, S.; Kühl, T.; Langfeld, B.; Löser, M.; Ma, X.; Nörtershäuser, W.; Sánchez, R.; Schramm, U.; Siebold, M.; Spiller, P.; Steck, M.; Stöhlker, T.; Walther, T.; Wang, H.; Weinheimer, C.; Wen, W.; Winters, D.

An improved moveable in vacuo XUV fluorescence detection system was employed for the laser cooling of bunched relativistic (β = 0.47) carbon ions at the Experimental Storage Ring (ESR) of GSI Helmholtzzentrum Darmstadt, Germany. Strongly Doppler boosted XUV fluorescence (∼90 nm) was emitted from the ions in a forward light cone after laser excitation of the 2s–2p transition (∼155 nm) by a new tunable pulsed UV laser system (257 nm). It was shown that the detected fluorescence strongly depends on the position of the detector around the bunched ion beam and on the delay (∼ns) between the ion bunches and the laser pulses. In addition, the fluorescence information could be directly combined with the revolution frequencies of the ions (and their longitudinal momentum spread), which were recorded using the Schottky resonator at the ESR. These fluorescence detection features are required for future laser cooling experiments at highly relativistic energies (up to γ∼ 13) and high intensities (up to 1011 particles) of ion beams in the new heavy ion synchrotron SIS100 at FAIR.

Permalink: https://www.hzdr.de/publications/Publ-36964
Publ.-Id: 36964


Control Systems and Data Management for High-Power Laser Facilities

Feister, S.; Cassou, K.; Dann, S.; Döpp, A.; Gauron, P.; Gonsalves, A. J.; Joglekar, A.; Marshall, V.; Neveu, O.; Schlenvoigt, H.-P.; Streeter, M. J. V.; Palmer, C. A. J.

The next generation of high-power lasers enables repetition of experiments at orders of magnitude higher frequency than was possible using the prior generation. Facilities requiring human intervention between laser repetitions need to adapt in order to keep pace with the new laser technology. A distributed networked control system can enable laboratory-wide automation and feedback control loops. These higher-repetition-rate experiments will create enormous quantities of data. A consistent approach to managing data can increase data accessibility, reduce repetitive data-software development, and mitigate poorly organized metadata. An opportunity arises to share knowledge of improvements to control and data infrastructure currently being undertaken. We compare platforms and approaches to state-of-the-art control systems and data management at high-power laser facilities, and we illustrate these topics with case studies from our community.

Keywords: control systems; data management; high-power lasers; high-repetation-rate; big data; community organization; metadata; standards; stabilization; feedback loops

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Permalink: https://www.hzdr.de/publications/Publ-36963
Publ.-Id: 36963


X-ray polarimetry and its application to strong-field QED

Yu, Q.; Xu, D.; Shen, B.; Cowan, T.; Schlenvoigt, H.-P.

Polarimetry is a highly sensitive method to quantify changes of the polarization state of light when passing through matter and is therefore widely applied in material science. The progress of synchrotron and X-Ray Free Electron Laser (XFEL) sources has led to significant developments of X-ray polarizers, opening perspectives for new applications of polarimetry to study source and beamline parameters as well as sample characteristics. X-ray polarimetry has shown to date a polarization purity of \num{<1.4e-11}, enabling detection of very small signals from ultrafast phenomena. A prominent application is the detection of vacuum birefringence. Vacuum birefringence is predicted in Quantum Electrodynamics (QED) and expected to be probed by combining an XFEL with a petawatt-class optical laser. We review how source and optical elements affect X-ray polarimeters in general and what qualities are required for detection of vacuum birefringence.

Keywords: X-rays; polarizer; polarimetry; birefringence; QED

Permalink: https://www.hzdr.de/publications/Publ-36962
Publ.-Id: 36962


Quantification of surface changes and volume losses of selected rock types due to different cleaning processes

Koch, T.; Fischer, C.; Schad, F.; Siegesmund, S.

The restorative cleaning of natural stones has a special significance for the preservation of important cultural assets or the slowing of their deterioration. Organisms such as fungi, lichens or mosses, but also emission dirt such as soot soften and otherwise damage both the surface and the internal structure of the building stone. In order to quantify the effects and in particular the abrasiveness of selected cleaning methods, cleaning experiments were carried out on six different naturally and artificially weathered rocks using cold water under high pressure, hot water under high pressure as well as hot-water steam. The types of rocks studied include marble, limestone, granite, sandstone and tuff. Surface changes in roughness and topography were quantified using two surface-sensitive methods: confocal microscopy as well as 3D shadow triangulation. The two high-pressure cleaning methods were found to have a significantly stronger abrasive effect than steam cleaning when the distances were too small. The cleaning performance, which was compared using biologically weathered samples, was lowest for steam cleaning. However, the high temperatures of the steam also permanently eliminate much of the biological matter on and under the surface, as observed in the field test. The results presented should make it possible for the conservator to assess, which cleaning procedures to use for the different rock varieties depending on the degree of weathering.

Permalink: https://www.hzdr.de/publications/Publ-36961
Publ.-Id: 36961


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