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41714 Publications

International Standardization of Basic Industrial Radiotracer and Radiation Applications – Current State

Jentsch, T.; Thereska, J.; Jin, J.-H.; Brisset, P.

Abstract

The International Atomic Energy Agency (IAEA) in cooperation with the International Society for Tracer and Radiation Applications (ISTRA) promotes the international standardization of basic industrial radiotracer and radiation applications. On behalf of IAEA and ISTRA experts from many countries employed in leading research centers and renowned industrial companies analyze existing international standards regarding the necessity of their update or amendment as well as the need for new standards in this field.
In June 2020, a new international standard on “Non-destructive testing - Gamma ray scanning method on process columns” was published as ISO 23159. About three years before, the experts detected the need to standardize this method, which is widely used in petrochemical and chemical plants to identify and locate the cause of malfunction inside various process columns.
In the field of flow rate measurements of fluids in conduits using radioactive tracers, a proposal for a new international standard was prepared in 2021. It united several old international standards in this technical field: measurement of water flow in closed conduits (ISO 2975), measurement of gas flow in conduits (ISO 4053) and measurement of liquid flow in open channels (ISO 9555). The new international standard with the title “Measurement of Fluid Flow Rate in Closed Conduits – Radioactive Tracer Methods” has now the state of a Draft International Standard (DIS) and will be published as ISO 24460 in this year.
Furthermore, two other international standards using radioactive tracer methods are under development. One of them is on leak testing in pressured vessels and underground pipelines, another one is on determination of concentration or density of suspended and deposited sediment in water bodies by radiometric methods. Both has already passed the New Work Item Proposal (NWIP) stage. The first one is being edited in ISO Technical Committee 135, Sub Committee 6, Working Group 1 (ISO TC 135/SC 6/WG 1), has the stage of a Committee Draft (CD) now and will be published as ISO 6640 in the middle of next year. The second one is being edited in ISO TC 113/SC 6/WG 5, has still the stage of a Working Draft (WD) and will be published as ISO 6366 also next year.
ISO standards are part of accreditation of radiotracer and radiation applications groups, facilitating the promotion and implementation of these competitive technologies in national, regional and international scale.

Keywords: International standards; ISO; radioactive tracers; radiometric methods

  • Lecture (Conference)
    NUTECH 2023 International Conference on Development and Applications of Nuclear Technologies, 20.-22.09.2023, Krakow, Polska

Permalink: https://www.hzdr.de/publications/Publ-36698


Trimorphic TaCrP – A diffraction and 31P solid state NMR spectroscopic study

Paulsen, C.; Maximilian Gerdes, J.; Svitlyk, V.; Kai Reimann, M.; Rabenbauer, A.; Nilges, T.; Ryan Hansen, M.; Pöttgen, R.

Abstract

The metal-rich phosphide TaCrP forms from the elements by step-wise solid state reaction in an alumina crucible (maximum annealing temperature 1180 K). TaCrP is trimorphic. The structural data of the hexagonal ZrNiAl high-temperature phase (space group P¯62m) was deduced from a Rietveld refinement. At room temperature TaCrP crystallizes with the TiNiSi type (Pnma, a = 623.86(5), b = 349.12(3), c = 736.78(6) pm, wR = 0.0419, 401 F2 values, 20 variables) and shows a Peierls type transition below ca. 280 K to the monoclinic low-temperature modification (P121/c1, a = 630.09(3), b = 740.3(4), c = 928.94(4) pm, β = 132.589(5)°, wR = 0.0580, 1378 F2 values, 57 variables). The latter phase transition is driven by pairwise Cr–Cr bond formation out of an equidistant chain in o-TaCrP. The phase transition was monitored via different analytical tools: differential scanning calorimetry, powder synchrotron X-ray diffraction, magnetic susceptibility measurements and 31P solid state NMR spectroscopy.

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-36697


A van der Waals Heterostructure with an Electronically Textured Moiré Pattern: PtSe₂/PtTe₂

Li, J.; Ghorbani Asl, M.; Lasek, K.; Pathirage, V.; Krasheninnikov, A.; Batzill, M.

Abstract

The interlayer interaction in Pt-dichalcogenides strongly affects their electronic structures. The modulations of the interlayer atom-coordination in vertical heterostructures based on these materials are expected to laterally modify these interlayer interactions and thus provide an opportunity to texture the electronic structure. To determine the effects of local variation of the interlayer atom coordination on the electronic structure of PtSe₂, van der Waals heterostructures of PtSe₂ and PtTe₂ have been synthesized by molecular beam epitaxy. The heterostructure forms a coincidence lattice with 13-unit cells of PtSe₂ matching 12-unit cells of PtTe₂, forming a moiré superstructure. The interaction with PtTe₂ reduces the band gap of PtSe₂ monolayers from 1.8 to 0.5 eV. While the band gap is uniform across the moiré unit cell, STS and dI/dV mapping identify gap states that are localized within certain regions of the moiré unit cell. Deep states associated with chalcogen pz-orbitals at binding energies of ~-2 eV also exhibit lateral variation within the moiré unit cell, indicative of varying interlayer chalcogen interactions. Density functional theory calculations indicate that local variations in atom coordination in the moiré unit cell causes variations in the charge transfer from PtTe2 to PtSe2 thus affecting the value of the interface dipole. Experimentally this is confirmed by measuring the local work function by field emission resonance spectroscopy, which reveals a large work function modulation of ~0.5 eV within the moiré structure. These results show that the local coordination variation of the chalcogen atoms in the PtSe2/PtTe2 van der Waals heterostructure induces a nanoscale electronic structure texture in PtSe₂.

Keywords: platinum dichalcogenides; van der Waals heterostructure; work function modulation; scanning tunneling microscopy; density functional theory

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Permalink: https://www.hzdr.de/publications/Publ-36696


Event generation in Julia and the path to GPUs

Hernandez Acosta, U.; Steiniger, K.; Reinhard, A.; Jungnickel, T.; Ehrig, S.; Bussmann, M.

Abstract

The inventors of the Julia programming language proclaim, that one can use high-level syntax to solve demanding numerical tasks. In order to evaluate this claim, we present possible applications of Julia by using it for the implementation of our Monte-Carlo event generator for laser-matter interaction. Especially the possible deployment of modern GPUs for demanding computing tasks during several stages of the event generation is discussed. In order to elaborate on these GPU capabilities, we show benchmarks of Julia's main programming interface for NVIDIA CUDA GPUs, namely `CUDA.jl`, and compare them with native CUDA-C++ implementations. Finally, Julia's capabilities for high-level abstraction for computations on heterogenous architectures are discussed and compared to low-level solutions like the `alpaka` library for C++.

Keywords: Julia programming language

  • Invited lecture (Conferences) (Online presentation)
    Compute Accelerator Forum, 08.03.2023, Geneva, Switzerland

Permalink: https://www.hzdr.de/publications/Publ-36695


Biogenic minerals formation by an Fe(III)-reducing Desulfitobacterium sp. isolate

Cardaio, I.; Kluge, S.; Cherkouk, A.; Müller, K.; Stumpf, T.; Mayordomo, N.

Abstract

Dissimilatory iron reduction is an anaerobic respiratory pathway, wherein ferric (Fe(III)) reducers couple the oxidation of organic acids, sugars and aromatic hydrocarbons to the reduction of Fe(III)-species [1]. This may lead to the formation of minerals such as magnetite (Fe(II)Fe(III)₂O₄) and siderite (Fe(II)CO₃) [2], which, in turn, can mediate the reduction of soluble pollutants as pertechnetate (Tc(VII)O₄⁻) to insoluble oxides (Tc(IV)O₂) [3].
The genus Desulfitobacterium contains obligate anaerobic bacteria that are capable of utilizing a wide range of electron acceptors, including nitrite, sulfite, metals, humic acids and halogenated organic compounds [4].
In this work, the Fe(III) reduction of a Desulfitobacterium species was examined. The microorganism has been isolated from bentonite, which is potentially used as geotechnical barrier in deep geological repositories for radioactive waste [5].
The cultivation conditions included DSMZ 579 medium with Na-acetate as electron donor to reduce Fe(III) citrate [6]. During cultivation, the formation of white precipitates was observed. The phases were collected both under aerobic and anaerobic conditions and repeatedly investigated by using Raman microscopy and powder X-ray diffraction (pXRD). It was noticed that the phases turned immediately to blue-greenish overnight under oxic conditions. Both Raman spectra and pXRD diffractograms can be attributed to vivianite (Fe(II)₃(PO₄)₂). Moreover, Raman spectra revealed the possible presence of pyrite (Fe(II)S₂), siderite, magnetite and hematite (FeIII₂O₃). These results suggest the ability of the bacterium of forming different Fe(II)-minerals. Notwithstanding, both methods indicate the change of the chemistry of the precipitates according to environmental factors. The Fe(II)-minerals formation by this microorganism depending on Fe(III)-compounds and background electrolytes is currently ongoing. The biogenic ferrous minerals will be studied regarding the reduction of Tc(VII)O₄⁻.

The authors acknowledge the German Federal Ministry of Education and Research (BMBF) for the financial support of NukSiFutur TecRad young investigator group (02NUK072).

[1] Lovley, 1993, Annual Review of Microbiology, 47:263-290
[2] Lee, et al., 2007, Geomicrobiology Journal, 24:1, 31-41
[3] Lloyd, et al., 2000, Appl Environ Microbiol., 66(9):3743-9
[4] Villemur et al., 2006, FEMS Microbiol Rev. 2006, 30(5):706-33
[5] Drozdowski J., et al., 2018, HZDR Annual Report, pp. 40, ISSN 2191-870
[6] https://www.dsmz.de/microorganisms/medium/pdf/DSMZ_Medium579.pdf. Accessed on 27.02.23

Keywords: iron reducing bacteria; technetium; biogenic minerals; Raman microscopy; X-ray diffraction

  • Open Access Logo Poster
    Goldschmidt 2023, 09.-14.07.2023, Lyon, Frankreich

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Permalink: https://www.hzdr.de/publications/Publ-36694


Messebericht ACHEMA 2022: Klassieren und Sortieren

Mütze, T.

Abstract

Auf der ACHEMA 2022 waren in Frankfurt 25 Anbieter von Klassierer-, Sortier-, Recycling- oder Aufbereitungsanlagen im engeren Sinne vertreten. Der vorliegende Bericht fasst kurz zusammen, welche Aussteller ihr Portfolio im Bereich der Mechanischen Prozesse vorstellten und was an Neuerungen gezeigt wurde. Schwerpunkte stellten u. a. Plan- und Taumelsiebmaschinen sowie Technologien für schnelle Siebbelagswechsel und zum Entfernen von Körnern außerhalb der Produktspezifikation dar.

Keywords: Automatische Klaubung; Hydrozyklone; Klassieren; Magnetscheidung; Sichter; Siebe; Sortieren

Permalink: https://www.hzdr.de/publications/Publ-36693


Messebericht ACHEMA 2022: Zerkleinern

Mütze, T.

Abstract

Auf der ACHEMA 2022 waren in Frankfurt 38 Anbieter von Zerkleinerungstechnik vertreten. Der vorliegende Bericht fasst kurz zusammen, welche Aussteller vertreten waren und was – vor allem an Neuerungen – gezeigt wurde. Schwerpunkte waren einerseits Maschinen zum Dispergieren verklumpter bzw. sehr feinkörniger Pulver zur besseren Verarbeitbarkeit oder zum Einmischen in Flüssigkeiten sowie andererseits Mahlkörpermühlen zur Fein- und Feinstmahlung.

Keywords: Zerkleinern; Brecher; Mühlen

Permalink: https://www.hzdr.de/publications/Publ-36692


Fluctuation Electron Microscopy on Amorphous Silicon and Amorphous Germanium

Radić, D.; Peterlechner, M.; Posselt, M.; Bracht, H.

Abstract

Variable resolution fluctuation electron microscopy experiments were performed on self-ion implanted amorphous silicon and amorphous germanium to analyze the medium-range order. The results highlight that the commonly used pair-persistence analysis is influenced by the experimental conditions. Precisely, the structural correlation length Λ, a metric for the medium-range order length scale in the material, obtained from this particular evaluation varies depending on whether energy filtering is used to acquire the data. In addition, Λ depends on the sample thickness. Both observations can be explained by the fact that the pair-persistence analysis utilizes the experimentally susceptible absolute value of the normalized variance obtained from fluctuation electron microscopy data. Instead, plotting the normalized variance peak magnitude over the electron beam size offers more robust results. This evaluation yields medium-range order with an extent of approximately (1.50± 0.50)nm for the analyzed amorphous germanium and around (1.10±0.20)nm for amorphous silicon

Keywords: amorphous germanium; amorphous silicon; fluctuation electron microscopy; medium-range order

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Permalink: https://www.hzdr.de/publications/Publ-36691


An experimental study of boiling two-phase flow in a vertical rod bundle with a spacer grid-Part 2: Effects of vane angle

Tas-Köhler, S.; Boden, S.; Franz, R.; Liao, Y.; Hampel, U.

Abstract

We performed boiling flow experiments and measured the void fraction in a 3 x 3 rod bundle including a spacer grid with split type vanes using X-ray computed tomography, which provides high-resolution time-averaged void data without disturbing the flow. We studied the effects of mixing vanes with different vane angles, namely, 20°, 29° and 40°, for a mass flux between 535 and 1950 kg/m2 s and the central rod being heated giving a heat flux of 85.7 kW/m2. The presence of vanes leads to an increase of the cross-sectional averaged void fraction up to an axial position of Z≈〖0.8D〗_h. After that, the void fraction decreases until 3D_h

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  • TOPFLOW Facility

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  • Secondary publication expected from 01.07.2024

Permalink: https://www.hzdr.de/publications/Publ-36690


Frontiers of challenging studies utilizing accelerator mass spectrometry in geoscience

Honda, M.; Martschini, M.; Lachner, J.; Wieser, A.; Marchhart, O.; Steier, P.; Golser, R.; Sakaguchi, A.

Abstract

The fission-product 90Sr (half-life 28.9 years) and 135Cs (half-life 2.3×106 years) are present in the environment. Strontium-90 is one of the most concerning nuclides in the assessment of internal exposure of residents because it can accumulate in bones and cause health problems. Therefore, it is essential to study the distribution of 90Sr in the environment and its temporal variation (90Sr enrichment in organisms and plants). On the other hand, 135Cs, which has a longer physical half-life than 137Cs (30.1 years), is expected to be utilized as a tracer to follow the long-term environmental fate of 137Cs, which is difficult to measure due to decay. These studies require high-throughput multi-sample analysis. However, as 90Sr and 135Cs are pure β-emitters, other β-emitters in the environmental samples (e.g., Ra isotopes, 137Cs, and 210Pb) must be entirely removed, which would interfere with β-ray detection. While this is impossible for the conventional β-ray detection method of 135Cs, it does work for 90Sr. Still, it requires a large sample volume due to the low concentrations of 90Sr in general environmental samples1). Therefore, the chemical separation of the target nuclide is very time-consuming and challenging for reliable quantification.
This study addressed solving these problems using accelerator mass spectrometry (AMS) for sensitive analysis of 90Sr and 135Cs in environmental samples2,3). AMS has the advantage of allowing more precise analysis of small sample volumes. However, the most concerning aspect of AMS for 90Sr and 135Cs is the interference of the isobars 90Zr and 135Ba. Therefore, the measurements of 90Sr and 135Cs were carried out at the University of Vienna (VERA). The AMS system is equipped with an "Ion cooler" that can effectively separate the isobars. For 90Sr, various molecular ions such as SrFn− and ZrFn− (n ≥ 1) were extracted from the target (a mixture of SrF2 and PbF2 in a weight ratio of 1:8) by Cs sputtering, and then the molecular ions with an m/q of 147 (90SrF3− and 90ZrF3−) were selectively passed through a 90° bending magnet. The ion beam (200-300 nA) was decelerated to ~30 eV and injected into the Ion cooler, an isobaric separation system with built-in radio-frequency quadrupole (RFQ). Collisions with a buffer gas mixture of He and O2 gas inside the RFQ reduced the ion energy to <1 eV. In addition, the O2 gas produces oxide ions and separated Zr. Here, a 12 W laser (532 nm) further suppressed Zr (neutralized 90ZrF3− by photo-detachment). In this isobaric separation system, Zr was suppressed by >107 for Sr (current ratio), and the overall Zr suppression is >1012 (ion source >105). The overall transmission efficiency of Sr was 0.4‰. Meanwhile, a simple chemical separation scheme was developed which efficiently separates Zr to maximize the isobaric separation performance of AMS: acid leaching → two-step chromatography with crown ether and anion exchange → SrF2 precipitation (2 days for the precipitation) to environmental reference materials (soil, beef bones, fish meat) with known 90Sr concentrations. The results showed that the 90Sr concentrations quantified by the AMS method agreed with the nominal values (quantified by the β-ray detection method) within a margin of error. Furthermore, based on the measurements of 1 mg of Sr carrier treated in the same manner as environmental samples, the detection limit of 90Sr by the AMS method achieved 1/10 (< 0.1 mBq, 90Sr/88Sr = 2.5×10-15) of the general detection limit of the β-ray detection method4). The highly sensitive analysis of 90Sr by AMS is promising for studies on the detailed distribution of 90Sr in individual (and even site-specific) corals and fishes with limited sample volumes. As for 135Cs, significant issues remain, such as efficient Ba separation in chemical separation, cross-contamination between samples in AMS ion sources, and preparing 135Cs reference materials. However, the detection limit for 135C was 0.3 µBq (135Cs/Cs atomic ratio was 7×10-12), demonstrating excellent results. Therefore, this study showed that the 135Cs AMS has the potential to apply geoscience.

Keywords: Accelerator Mass Spectrometry; Isobar; Chemical Separation; Laser photo-detachment; 90Sr; 135Cs

  • Invited lecture (Conferences)
    71st Annual Conference on Mass Spectrometry, Japan, 15.-17.05.2023, Osaka, Japan

Permalink: https://www.hzdr.de/publications/Publ-36689


Immunotargeting of Cancer Stem Cells.

Köseer, A. S.; Di Gaetano, S.; Arndt, C.; Bachmann, M.; Dubrovska, A.

Abstract

The generally accepted view is that CSCs hijack the signaling pathways attributed to normal stem cells that regulate the self-renewal and differentiation processes. Therefore, the development of selective targeting strategies for CSC, although clinically meaningful, is associated with significant challenges because CSC and normal stem cells share many important signaling mechanisms for their maintenance and survival. Furthermore, the efficacy of this therapy is opposed by tumor heterogeneity and CSC plasticity. While there have been considerable efforts to target CSC populations by the chemical inhibition of the developmental pathways such as Notch, Hedgehog (Hh), and Wnt/β-catenin, noticeably fewer attempts were focused on the stimulation of the immune response by CSC-specific antigens, including cell-surface targets. Cancer immunotherapies are based on triggering the anti-tumor immune response by specific activation and targeted redirecting of immune cells toward tumor cells. This review is focused on CSC-directed immunotherapeutic approaches such as bispecific antibodies and antibody-drug candidates, CSC-targeted cellular immunotherapies, and immune-based vaccines. We discuss the strategies to improve the safety and efficacy of the different immunotherapeutic approaches and describe the current state of their clinical development.

Keywords: CAR-T cells; CSC; bsAB; cancer stem cells; cancer vaccines; immunotherapy

Permalink: https://www.hzdr.de/publications/Publ-36685


Synthesis and Characterization of a Masked Terminal Nickel-Oxide Complex

Heim, P.; Spedalotto, G.; Lovisari, M.; Gericke, R.; O’Brien, J.; Farquhar, E. R.; McDonald, A. R.

Abstract

In exploring terminal nickel-oxo complexes, postulated to be the active oxidant in natural and non-natural oxidation reactions, we report the synthesis of the pseudo-trigonal bipyramidal Ni(II) complexes (K)[Ni(II)(LPh)(DMF)] (1[DMF]) and (NMe₄)₂[Ni(II)(LPh)(OAc)] (1[OAc]) (LPh = 2,2’,2’’-nitrilo-tris-(N-phenylacetamide); DMF = N,N-dimethylformamide; OAc = acetate). Both complexes were characterized using NMR, FTIR, ESI-MS, and X-ray crystallography, showing the LPh ligand to bind in a tetradentate fashion, together with an ancillary donor. The reaction of 1[OAc] with peroxyphenyl acetic acid (PPAA) resulted in the formation of [(LPh)Ni(III)-O-H···OAc]²-, 2, that displays many of the characteristics of a terminal Ni=O species. 2 was characterized by UV-Vis, EPR, and XAS spectroscopies and ESI-MS. 2 decayed to yield a Ni(II)-phenolate complex 3 (through aromatic electrophilic substitution) that was characterized by NMR, FTIR, ESI-MS, and X-ray crystallography. 2 was capable of hydroxylation of hydrocarbons and epoxidation of olefins, as well as oxygen atom transfer oxidation of phosphines at exceptional rates. While the oxo-wall remains standing, this complex represents an excellent example of a masked metal-oxide that displays all of the properties expected of the ever elusive terminal M=O beyond the oxo-wall.

Keywords: bioinorganic chemistry; high-valent nickel; hydrocarbon oxidation; oxo-wall; peracid activation

Permalink: https://www.hzdr.de/publications/Publ-36684


High-Throughput Gel Microbeads as Incubators for Bacterial Competition Study

Nguyen Le, T. A.; Zhao, X.; Bachmann, M.; Ruelens, P.; de Visser, J. A. G. M.; Baraban, L.

Abstract

Bacteria primarily live in structured environments, such as colonies and biofilms, attached to surfaces or growing within soft tissues. They are engaged in local competitive and cooperative interactions impacting our health and well-being, for example, by affecting population-level drug resistance. Our knowledge of bacterial competition and cooperation within soft matrices is in-complete, partly because we lack high-throughput tools to quantitatively study their interactions. Here, we introduce a method to generate a large amount of agarose microbeads that mimic the natural culture conditions experienced by bacteria to co-encapsulate two strains of fluores-cence-labeled Escherichia coli. Focusing specifically on low bacterial inoculum (1–100 cells/capsule), we demonstrate a study on the formation of colonies of both strains within these 3D scaffolds and follow their growth kinetics and interaction using fluorescence microscopy in highly replicated experiments. We confirmed that the average final colony size is inversely proportional to the inoculum size in this semi-solid environment as a result of limited available resources. Further-more, the colony shape and fluorescence intensity per colony are distinctly different in mono-culture and co-culture. The experimental observations in mono- and co-culture are compared with predictions from a simple growth model. We suggest that our high throughput and small foot-print microbead system is an excellent platform for future investigation of competitive and co-operative interactions in bacterial communities under diverse conditions, including antibiotics stress.

Keywords: millifluidic; high-throughput; agarose microbeads; co-culture; bacterial co-existence; fluorescence

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Permalink: https://www.hzdr.de/publications/Publ-36682


Unraveling the Np(V) Sorption on the Nuclear Fuel Cladding Corrosion Product ZrO₂: a Batch, Spectroscopic and Modeling Combined Approach

Jessat, I.; Foerstendorf, H.; Roßberg, A.; Scheinost, A.; Lützenkirchen, J.; Heim, K.; Stumpf, T.; Jordan, N.

Abstract

Zirconia (ZrO₂), the main corrosion product of the zircaloy cladding material of nuclear fuel rods, might potentially act as the first barrier for radionuclides. Thus, the interactions of radionuclides, such as the long-lived actinide neptunium, with zirconia have to be considered in the safety assessment process of a repository for radioactive waste. The sorption of Np(V) onto zirconia (ZrO₂) was investigated in the absence of carbonate at the macroscopic and molecular scale. For the macroscopic description, pH-dependent batch sorption experiments under varying ionic strength (0.1 and 0.01 mol∙L⁻¹ NaCl), Np(V) concentration (1∙10⁻⁶ or 6∙10⁻⁶ mol∙L⁻¹) and solid-to-liquid ratio (m/V = 0.5 or 4 g∙L⁻¹ ZrO₂) were conducted. Np(V) sorption isotherms at pH 4.5 and 6.0 were additionally obtained at 0.01 mol∙L⁻¹ NaCl. The Np(V) uptake on zirconia strongly depends on pH, with sorption starting from acidic pH and maximum sorption was reached at pH 6 and above. Increasing the m/V ratio caused a significant shift of the sorption edge towards lower pH values. This indicates the presence of different kinds of sorption sites, which was supported by the results of the Np(V) sorption isotherms, where the shape of the isotherm suggested the presence of strong and weak sorption sites. The Np(V) uptake was independent of ionic strength, suggesting the presence of inner-sphere Np(V) surface complexes on zirconia. This was also supported by zeta potential measurements where a shift of the isoelectric point of the pristine zirconia towards higher pH values in the presence of Np(V) was observed.
Molecular level investigations by means of spectroscopic techniques, namely in situ attenuated total reflection Fourier transform Infrared Spectroscopy (ATR FT-IR) and extended X-ray absorption fine structure spectroscopy (EXAFS), confirmed the predominant presence of Np(V) inner-sphere complexes on the zirconia surface. EXAFS experiments conducted in the weak sorption site regime revealed the formation of one Np(V) bidentate inner-sphere surface complex. Spectroscopic techniques could not be applied to gain information about the presence and structure of Np(V) surface species at such low Np(V) concentrations, where the strong site regimes could be investigated.
The derived information at the macroscopic and molecular levels were used to parameterize a surface complexation model. The Np(V) sorption edges and isotherms could be described with a 1-pK three plane CD-MUSIC model. The derived thermodynamic constants are expected to help to better predict the environmental fate of Np(V) in the context of nuclear waste repository assessments and will also support the appraisal of safety-relevant scenarios for the extended interim storage of spent nuclear fuel.

Keywords: neptunium(V); zirconia; sorption; IR; EXAFS; SCM; ZrO₂; spectroscopy; modelling

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Permalink: https://www.hzdr.de/publications/Publ-36679


Data publication: Membrane-free alkali metal-iodide battery with a molten salt

Lee, J.; Monrrabal Marquez, G.; Sarma, M.; Lappan, T.; Hofstettet, Y. J.; Trtik, P.; Landgraf, S.; Ding, W.; Kumar, S.; Vaynzof, Y.; Weber, N.; Weier, T.

Abstract

Raw data from experiments with membrane-free alkali metal-iodide cells containing XPS results, phase-diagram calculations, neutron radiography images, electrochemical cycling data, and electron microscope images of the carbon felt used.

Keywords: liquid metal batteries; alkali metal-iodide batteries; liquid metal electrodes; low-temperature molten salt; membrane-free energy storage; neutron radiography

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Permalink: https://www.hzdr.de/publications/Publ-36678


Band-to-band tunneling switches based on two-dimensional van der Waals heterojunctions

Chava, P.; Fekri, Z.; Vekariya, Y. N.; Mikolajick, T.; Erbe, A.

Abstract

Quantum mechanical band-to-band tunneling (BTBT) is a type of carrier injection mechanism that is responsible for the electronic transport in devices like tunnel field effect transistors (TFETs), which hold great promise in reducing the subthreshold swing below the Boltzmann limit. This allows scaling down the operating voltage and the off-state leakage current at the same time, and thus reducing the power consumption of metal oxide semiconductor transistors. Conventional group IV or compound semiconductor materials suffer from interface and bulk traps, which hinders the device performance owing to the increased trap induced parasitics. Alternatives like two-dimensional materials (2DMs) are beneficial for realizing such devices due to their ultra-thin body and atomically sharp interfaces with van der Waals interactions, which significantly reduce the trap density, compared to their bulk counterparts, and hold the promise to finally achieve the desired low voltage operation. In this review, we summarize the recent progress on such devices, with a major focus on heterojunctions made of different 2DMs. We review different types of emerging device concepts, architectures and the tunneling mechanisms involved by analytically studying various simulations and experimental devices. We present our detailed perspective on the current developments, major roadblocks and key strategies for further improvements of the TFET technology based on 2D heterojunctions to match industry requirements. The main goal of this paper is to introduce the reader to the concept of tunneling especially in van der Waals devices and provide an overview of the recent progress and challenges in the field.

Keywords: 2D materials; heterojunctions; band-to-band tunneling; tunnel field effect transistor; tunnel diode

Permalink: https://www.hzdr.de/publications/Publ-36676


Generalized Laguerre Mosaics as versatile toolbox for microstructure modelling

van den Boogaart, K. G.; Tolosana Delgado, R.; Ballani, F.

Abstract

The particle based simulation of minerals processing often requires
models of 3D particles, while only insufficiently resolved 3D
information from CT or sufficiently resolved 2D information on the
structure of the material is available. Fitted and simulated
microstructure models can support us with relevant 3D microstructures.

The contribution proposes several steps to generalize 3D
Laguerre mosaics that allow to recreate various typical features of
microstructures with meaningful parameters to the simulation process:
Multiple phases with different abundance, preferred contacts, different
grain sizes, spatial variation of properties, flattened crystallites,
preferred orientation, flat and rounded boundaries, etc.

A special feature of the model is the possibility to change the parameters
gradually for the same simulation, such that one can track the effect
of the parameters visually and for estimation algorithms with lower
variability than with a resimulation.

The same microstructure can be computed for 3D voxel spaces, in 2D
sections and on MPS type patterns for estimation of high order
statistics.

Keywords: Geometallurgy; Stochastic Geometry; Microstructure Simulation

  • Lecture (Conference)
    IAMG2023, 05.-12.08.2023, Trontheim, Kongeriket Noreg

Permalink: https://www.hzdr.de/publications/Publ-36675


Structural MATerias research on parameters influencing the material properties of RPV steels for safe long-term operation of PWR NPPs

Kolluri, M.; Martin, O.; Naziris, F.; D’Agata, E.; Gillemot, F.; Brumovsky, M.; Ulbricht, A.; Autio, J.-M.; Shugailo, O.; Horvath, A.

Abstract

This article provides a comprehensive overview of the STRUMAT-LTO project. Embrittlement of the reactor pressure vessel (RPV) due to neutron irradiation and high temperature conditions impose critical challenges for long-term operation (LTO) of pressurized water reactors (PWRs). Significant amount of past research conducted on RPV ageing phenomena has helped to enhance the understanding of the flux effect and the impact of chemical/microstructural heterogeneities on RPV embrittlement. Nonetheless, several unresolved questions regarding RPV embrittlement persist, such as the conflicting viewpoints on the underlying mechanisms that lead to accelerated embrittlement at high fluence conditions in certain low-copper (Cu) RPV steels and the synergistic
effect between nickel, manganese, and silicon (Ni-Mn-Si). Also, the accuracy of embrittlement trend curves (ETCs) for LTO beyond 60 years and the applicability of the master curve approach at high fluences for small/sub-sized specimens require further study. The aim of the STRUMAT-LTO is to address the above-mentioned scientific gaps in RPV embrittlement by employing a unique set of RPV steel specimens constituting systematic variations in Ni, Mn, and Si content, which are irradiated to high fluences resembling reactor operation beyond 60 years within the LYRA-10 experiment at high flux reactor (HFR) in Petten. The STRUMAT-LTO project has received funding from the Euratom research and training programme 2019–2020 under grant agreement
n◦945272. The project has a duration of 48 months.

Keywords: STRUMAT-LTO; RPV embrittlement; LYRA-10; HFR; mini-CT; LWRs; Long term operation; Embrittlement trent curve

Permalink: https://www.hzdr.de/publications/Publ-36674


Vacancy complexes in Cd3As2

Rice, A. D.; Liedke, M. O.; Butterling, M.; Hirschmann, E.; Wagner, A.; Haegel, N. M.; Alberi, K.

Abstract

Epitaxial growth of the three-dimensional topological semimetal Cd3As2 on semiconductor substrates enables its use and integration in device applications. Epitaxy also provides an avenue for varying and controlling point defects through modification of the chemical potential during growth. In turn, knowledge of the point defects that are generated in Cd3As2 epilayers will aid the interpretation of electron transport behavior and guide growth efforts to produce material with low defect densities. Point defects in Cd3As2 epilayers grown by molecular beam epitaxy with varying As/Cd flux ratios are probed by positron annihilation spectroscopy. We find that lower As/Cd flux ratios produce higher concentrations of point defects. Remarkably, the measurements indicate that the average defect size is larger than a monovacancy. The data presented here contribute to an evolving picture of vacancy point defects in Cd3As2 and can be used to direct future investigation of the defect-transport relationships in this emerging electronic material.

Keywords: Cd3As2; semiconductors; defects; positron annihilation spectroscopy

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-36673


Chirality coupling in topological magnetic textures with multiple magnetochiral parameters

Volkov, O.; Wolf, D.; Pylypovskyi, O.; Kakay, A.; Sheka, D. D.; Büchner, B.; Faßbender, J.; Lubk, A.; Makarov, D.

Abstract

Chiral effects originate from the lack of inversion symmetry within the lattice unit cell or sample’s shape. Being mapped onto magnetic ordering, chirality enables topologically non-trivial textures with a given handedness. Here, we demonstrate the existence of a static 3D texture characterized by two magnetochiral parameters being magnetic helicity of the vortex and geometrical chirality of the core string itself in geometrically curved asymmetric permalloy cap with a size of 80 nm and a vortex ground state. We experimentally validate the nonlocal chiral symmetry breaking effect in this object, which leads to the geometric deformation of the vortex string into a helix with curvature 3 μm−1 and torsion 11 μm−1. The geometric chirality of the vortex string is determined by the magnetic helicity of the vortex texture, constituting coupling of two chiral parameters within the same texture. Beyond the vortex state, we anticipate that complex curvilinear objects hosting 3D magnetic textures like curved skyrmion tubes and hopfions can be characterized by multiple coupled magnetochiral parameters, that influence their statics and field- or current-driven dynamics for spin-orbitronics and magnonics.

Keywords: Non-local chiral symmetry breaking; Magnetic vortex

Permalink: https://www.hzdr.de/publications/Publ-36672


Eine Infrastruktur zur Harmonisierung von Datenstrukturen und Semantik

Steinmeier, L.; Ballani, F.; Rau, F.

Abstract

Derzeit wird viel daran geforscht, wie Forschungsdaten im Sinne der FAIR-Prinzipien publiziert werden können. Diese Prinzipien bereits während der Erfassung und Bearbeitung der Daten, also zu einem frühen Zeitpunkt im Forschungsdatenlebenszyklus anzuwenden, bringt viele Vorteile mit sich. Wir stellen eine Softwareinfrastruktur vor, die dies unterstützen soll. Hierbei legen wir den Schwerpunkt auf die Aspekte des Austausches und der Harmonisierung von Datenstrukturen und Semantik und beschreiben auch, wie eine angebundene Endnutzersoftware aussehen kann.

Die Infrastruktur basiert auf folgender Top-Level-Architektur: Teilnehmende Parteien können eigene Instanzen von Datenstruktur- und Semantik-"Warehouses" mit privaten und öffentlichen Teilen betreiben. Ein globaler Index macht dann die öffentlichen Teile aller Warehouses auffindbar und zugänglich. Diese Infrastruktur muss die Anbindung beliebiger Endnutzersoftware durch einen gemeinsamen Kommunikationsstandard ermöglichen, da die Anforderungen an Dateneingabe und -bearbeitung zwischen verschiedenen Forschungsfeldern sehr unterschiedlich ausfallen können. Die Kommunikation soll grundsätzlich über Graphdaten erfolgen, da diese besonders geeignet sind, um vernetzte Inhalte abzubilden.

Eine solche Infrastruktur kann u. a. folgende Funktionen in Endnutzersoftware unterstützen: Bei der Eingabe von Daten können automatisch bestehende Datenstrukturen und Semantiken zur Verwendung vorgeschlagen werden; bestehende Daten, die gleiche oder ähnliche Strukturen und Semantiken verwenden, können gefunden und verglichen werden; Datenstrukturen und Semantiken können öffentlich diskutiert werden, um sie von und für die jeweiligen Nutzergemeinschaften weiter zu harmonisieren und zu entwickeln.

Zur Demonstration der Funktionen und Vorteile einer derartigen Infrastruktur entwickeln wir eine Proof-of-Concept-Endnutzersoftware in Form eines Graphdateneditors. Dieser Editor wird Forschende beim FAIRen Erfassen von Daten durch die folgenden Funktionalitäten unterstützen: Zu domänenunabhängigen Themen (z. B. Einheiten) stellt er ihnen Standards für Strukturen und Semantik zur Verfügung. Er ermöglicht ihnen, bestehende Ressourcen wie Geräte oder Datensätze mit ihrer Arbeit zu verknüpfen. Und er fördert unter Verwendung eines Prototypen der skizzierten Infrastruktur die Harmonisierung von Datenstrukturen und Semantik mit anderen Nutzer:innen.

Keywords: FAIR; Semantik; Datenstruktur; Harmonisierung; Graphdaten; Editor; Infrastruktur

  • Poster
    Datenräume in Deutschland und Europa gestalten - Impulse der Wissenschaft, 24.-25.04.2023, Hannover, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36670


Helmholtz Metadata Collaboration - Datenräume innerhalb und mit der Helmholtz-Gemeinschaft gestalten

Ballani, F.; Curdt, C.; Lorenz, S.; Süß, W.

Abstract

Daten sind ein essentieller Bestandteil heutiger Forschungsaktivitäten. Ein leistungsfähiges und zukunftsorientiertes Forschungsdatenmanagement kann die Effizienz von Forschung, die langfristige Verfügbarkeit generierter Daten und die Reproduzierbarkeit entsprechender Ergebnisse verbessern. Ein wesentlicher Baustein, wie er in den FAIR-Prinzipien umrissen wird, sind dabei Metadaten. Um dieses Thema aufzugreifen, hat die Helmholtz-Gemeinschaft Deutscher Forschungszentren die Plattform "Helmholtz Metadata Collaboration (HMC)" ins Leben gerufen und mit der Aufgabe betraut, Beratungsangebote, Informationen und Werkzeuge für einen effizienten Umgang mit Metadaten und damit zur Verbesserung der FAIRness von Helmholtz-Forschungsdaten zur Verfügung zu stellen.
Von großer Bedeutung für den Erfolg von HMC ist die Vernetzung in den Communities der Helmholtz-Forschungsbereiche Energie, Erde und Umwelt, Gesundheit, Materie, Information sowie Luft- und Raumfahrt und Verkehr. HMC stützt sich daher auf eine verteilte Struktur von sechs disziplinspezifischen Metadaten-Hubs, die innerhalb ihrer Communities Kompetenzen aktivieren, Ideen fördern und Anforderungen sammeln, um daraus Lösungen für die aktuellen Herausforderungen im Bereich der Metadaten zu entwickeln. Ein mit den technischen Entwicklungen beauftragtes, zentral verankertes Team wirkt unterstützend bei der Implementierung empfohlener Lösungen, Dienste und Werkzeuge mit. Derartige technische Lösungen, allgemein verwendbare Prozesse sowie Angebote zu Schulung, Weiterbildung und Beratung werden fortlaufend erweitert und zur Verfügung gestellt.
HMC ist Teil eines größeren Helmholtz-Förderprogramms, das sich mit unterschiedlichen Herausforderungen der Digitalisierung von Forschung auseinandersetzt, und steht in engem Kontakt mit Helmholtz Open Science. Darüber hinaus sind die Aktivitäten von HMC in den nationalen und internationalen Kontext (z. B. RDA, EOSC, NFDI) und entlang der wissenschaftlichen Disziplinen sowie der Informations- und Datenwissenschaft eingebettet, um die Kompatibilität mit der größeren Wissenschaftsgemeinschaft zu gewährleisten.
Ziel ist neben der Gestaltung einer internen Helmholtz-Plattform, die Etablierung eines öffentlichen, offenen und langfristig verfügbaren Gemeinschaftsdienstes für den Umgang mit Metadaten in der Wissenschaft.

Keywords: Helmholtz Metadata Collaboration

  • Poster
    Herrenhäuser Konferenz "Datenräume in Deutschland und Europa gestalten - Impulse der Wissenschaft", 24.-25.04.2023, Hannover, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36669


Rollen und Strukturen für eine vollständige Erfassung und Publikation von Forschungsdaten

Rau, F.; Ballani, F.; Steinmeier, L.; van den Boogaart, K. G.

Abstract

Ein Datensatz gilt als vollständig, wenn neben den reinen Daten (z. B. Messwerte) auch weiterführende Informationen, wie Entstehung und Nutzungslizenz, vorliegen. Dies erfordert neben der vollständigen Erfassung der Daten und Metadaten auch Hilfestelllungen bzw. Instruktionen für die Erfassung und Nutzung sowie einer Infrastruktur zur Speicherung, Publikation und eindeutigen Identifikation. Eine solche "Wertschöpfungskette" setzt sich aus verschiedenartigen Prozessen zusammen, die von Personen in definierten Rollen bearbeitet werden sollten. Auch gilt es, eine Infrastruktur bereitzustellen, die zum einen eine präzise Eingabemaske für den konkreten Fall des Anwenders generiert, aber zum anderen allgemeine Suchanfragen zielgerichtet auf die richtigen Datensätze lenken muss. Und natürlich ist dieses gesamte Konstrukt nicht ohne Regeln und Dokumentation beherrschbar und muss mit einem angepassten Schulungsangebot und einer intuitiven Benutzeroberfläche ausgestattet sein. Das Schulungsangebot richtet sich auch an Personen mit Rollen bzw. zugewiesenen Aufgaben im Datenmanagementsystem um sicherzustellen, dass die Rollen durch die Definition von notwendigen Qualifikationen mit der notwendigen Qualität ausgeführt werden. Eine Plausibilitätsprüfung, die die erwartete Flexibilität des Systems berücksichtigt, garantiert die Konsistenz der Datensätze. In einer der höchsten Ausbaustufen folgt der Plausibilitätsprüfung eine Art Selbstheilungsmechanismus, der dem Anwender einen Datensatz gemäß den Vorgaben vorschlägt oder dessen erneutes Eingreifen gänzlich obsolet macht.
In diesem Beitrag soll der Fokus auf den Rollen und auf der Interaktion mit dem Datenmanagementsystem liegen. Alle notwendigen Qualifikationen und Aufgabenfelder werden dabei den Rollen zugeordnet. Der Vorteil der Unterteilung in Rollen ist es, dass offenbleibt, ob die zusätzlichen Aufgaben durch bestehendes oder neues Personal abgedeckt werden oder ob nicht eine Person mehrere Rollen innehat. Damit kann der konkrete Personalansatz an die eigenen Bedürfnisse angepasst werden.

  • Poster
    Datenräume in Deutschland und Europa gestalten - Impulse der Wissenschaft, 24.-25.04.2023, Hannover, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36668


Advances and new ideas for neutron-capture astrophysics experiments at CERN n_TOF

Domingo-Pardo, C.; Babiano-Suarez, V.; Balibrea-Correa, J.; Caballero, L.; Ladarescu, I.; Lerendegui-Marco, J.; Tain, J. L.; Tarifeño-Saldivia, A.; Aberle, O.; Alcayne, V.; Altieri, S.; Amaducci, S.; Andrzejewski, J.; Bacak, M.; Beltrami, C.; Bennett, S.; Bernardes, A. P.; Berthoumieux, E.; Boromiza, M.; Bosnar, D.; Caamaño, M.; Calviño, F.; Calviani, M.; Cano-Ott, D.; Casanovas, A.; Cerutti, F.; Cescutti, G.; Chasapoglou, S.; Chiaveri, E.; Chiera, N. M.; Colombetti, P.; Colonna, N.; Camprini, P. C.; Cortés, G.; Cortés-Giraldo, M. A.; Cosentino, L.; Cristallo, S.; Dellmann, S.; Di, C. M.; Di, M. S.; Diakaki, M.; Dietz, M.; Dressler, R.; Dupont, E.; Durán, I.; Eleme, Z.; Fargier, S.; Fernández, B.; Fernández-Domínguez, B.; Finocchiaro, P.; Fiore, S.; García-Infantes, F.; Gawlik-Ramięga, 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.; Käppeler, F.; Kaur, G.; Kimura, A.; Knapová, I.; Köster, U.; Kokkoris, M.; Krtička, M.; Kyritsis, N.; Lederer-Woods, C.; Lerner, G.; Manna, A.; Martínez, T.; Masi, A.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Maugeri, E. A.; Mazzone, A.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mönch, I.; Mucciola, R.; Murtas, F.; Musacchio-Gonzalez, E.; Musumarra, A.; Negret, A.; Pérez, D. R. A.; Pérez-Maroto, P.; Patronis, N.; Pavón-Rodríguez, J. A.; Pellegriti, M. G.; Perkowski, J.; Petrone, C.; Pirovano, E.; Plaza, J.; Pomp, S.; Porras, I.; Praena, J.; Quesada, J. M.; Reifarth, R.; Rochman, D.; Romanets, Y.; Rubbia, C.; Sánchez, A.; Sabaté-Gilarte, M.; Schillebeeckx, P.; Schumann, D.; Sekhar, A.; Smith, A. G.; Sosnin, N. V.; Stamati, M.; Sturniolo, A.; Tagliente, G.; Tarrío, D.; Torres-Sánchez, P.; Turko, J. A. B.; Urlass, S.; Vagena, E.; Valenta, S.; Variale, V.; Vaz, P.; Vecchio, G.; Vescovi, D.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Woods, P. J.; Wright, T.; Zarrella, R.; Žugec, P.

Abstract

This article presents a few selected developments and future ideas related to the measurement of (n,γ) data of astrophysical interest at CERN n_TOF. The MC-aided analysis methodology for the use of low-efficiency radiation detectors in time-of-flight neutron-capture measurements is discussed, with particular emphasis on the systematic accuracy. Several recent instrumental advances are also presented, such as the development of total-energy detectors with γ-ray imaging capability for background suppression, and the development of an array of small-volume organic scintillators aimed at exploiting the high instantaneous neutron-flux of EAR2. Finally, astrophysics prospects related to the intermediate i neutron-capture process of nucleosynthesis are discussed in the context of the new NEAR activation area.

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Permalink: https://www.hzdr.de/publications/Publ-36667


Experimental and theoretical study on the production of carbide-rich composite nano-coatings

Fogarassy, Z.; Kentsch, U.; Panjan, P.; Racz, A. S.

Abstract

Carbides are known for high hardness and corrosion resistance and therefore applicable as protective coatings. C/Si and C/W multilayers (the individual layer thicknesses were between 10 and 20 nm) have been irradiated at room temperature by argon and xenon ions. The energies varied between 40 and 120 keV while the fluences were in the range of 0.07 - 6 × 10¹⁶ ions/cm². The SRIM simulation was applied to have the proper ion energy. The irradiation induced intermixing and carbide (SiC and WC) formation at the interfaces already for the lowest irradiation fluence. The component in-depth distribution has been determined by AES depth profiling which showed that it varied greatly as a function of the irradiation conditions and layer structure. In both material pair the thickness of the produced carbide increased with square root of fluence but the mixing mechanism were different: local spike for C/W and ballistic for C/Si. The mixing efficiency was lower for the C/Si than for the C/ W.

Keywords: WC; SiC; Carbide; Irradiation; Multilayer; Mixing

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Permalink: https://www.hzdr.de/publications/Publ-36666


Efficient Production of the PET Radionuclide Lanthanum-133

Brühlmann, S. A.; Kreller, M.; Pietzsch, H.-J.; Kopka, K.; Mamat, C.; Walther, M.; Reissig, F.

Abstract

Ziel/Aim:

Targeted Alpha Therapy is a research field of highest interest in specialized radionuclide therapy. In particular the radionuclide actinium-225 provides all necessary physical and chemical properties for a successful clinical application. Although the macropa chelator has shown beneficial properties regarding labeling and stability in vivo as compared with DOTA, the former lacks an imaging counterpart to actinium-225. On the other hand, lanthanum is a perfect surrogate for actinium. The imaging properties of the β+-emitter lanthanum-133 makes it an attractive candidate as a theranostic matched pair to actinium-225. This project aims at the cyclotron-based production of lanthanum-133 with high radionuclidic purity for theranostic purposes.
Methodik/Methods:
Silver discs were filled with [Ba-134]BaCO3 and capped with a platinum foil. One-hour proton irradiations (18.6 MeV, 15 µA) were performed with the HZDR TR-FLEX (ACSI) cyclotron. The powder target was then opened and the dry solid dissolved in HNO3. Separation was carried out with branched DGA cartridge, although other anion-exchange resins are also under investigation. The fractions containing Ba were collected for recovery. Test radiolabeling of macropa-derived PSMA inhibitors previously published by our group was performed in the MBq/nmol range.
Ergebnisse/Results:
Activity yields of 1.8 GBq lanthanum-133 (decay-corrected to EOB) were achieved, with corresponding lanthanum-135 impurities below 0.4 % and no other La radionuclides detected. The product was collected in diluted HCl, with ca. 80 % activity eluted in the second mL. Quantitative radiolabeling was achieved with ligand concentrations down to the µM range.
Schlussfolgerungen/Conclusions:
Lanthanum-133 with high radionuclidic purity was produced for the first time. Considering future medical demands, the scale up to radioactivity amounts that are needed for clinical application purposes could be achieved by increasing the target mass, beam current and irradiation time.

  • Contribution to proceedings
    NuklearMedizin 2023, 19.-22.04.2023, Leipzig, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36665


Nanoscale mineral/contaminant redox reaction processes: impact on oxyanion contaminant fate in oscillating anoxic environments

Charlet, L.; Guida, C.; Poulain, A.; Ding, R.; Ramothe, V.; Maria Papaslioti, E.; Kirsch, R.; Fernandez-Martinez, A.; Scheinost, A.; Marc Greneche, J.; Menguy, N.; Rosso, K. M.

Abstract

Oscillating oxic/anoxic conditions induces processes at mineral-Kuid
interfaces aeecting the speciation and fate of redox active elements. Such
Kuctuations occur in natural environments (at watershed and delta water
table or in lake water chemocline) and in engineered systems (in oil reDnery
drainage water peatbogs or nuclear waste repository). In presence of aqueous
sulDde or ferrous iron ions, Se, Sb, Pu and Re undergo heterogeneous
reductive precipitation. At the nanosecond scale, selenate adsorption onto
the net pyrite surface is shown by ab-initio computations to proceed via the
formation of a chemical bond between the oxyanion oxygen atom and a
surface Fe atom, weakening the other Se-O bonds and reducing Se atom
oxydation state. At hour-to-day scale, mobile Se(VI), Se(IV), Sb(V), Pu(V) and
Re(VII) oxyanions are shown by strictly anoxic wet chemistry experiments,
XAFS and Mossbauer spectroscopy [1] to be reduced, in presence of
nanosized particles (iron sulDdes (mackinawite or pyrite) [2], oxides
(magnetite) [3] [4] [5] or clays [6]) and aqueous iron (II) or S(-II), to solids (Se(0),
Sb O , PuO , Re0 , ReS or Re(0)) or to highly speciDc Sb(III) [7] and Pu(III) [8]
sorption complexes. STEM-HAADF microscopy demonstrates the formation of
Se(0) trigonal gray selenium nanowires after co-adsorption of selenate and
ferrous iron ions on 10 nm nanomagnetite [4], a reaction which results from a
complex, kinetically controlled interplay of intermediate reduced surface
complexes and transport of these reduced species to the tip of the nanowires.
These processes in far-from-equilibrium conditions are of prime importance
in the safety assessment of petroleum industry and geological repositories, as
well as in the bioavailability to crop or human beings.
[1] Charlet et al., 2022, J. Mat. Res. DOI: 10.1557/s43578-022-00823-8 [2] Son et
al., 2022, Geochim. Cosmochim. Acta 338 : 220–228. [3] Goberna-Feron et al.,
2021, Env. Sci. & Tech. 55, 3021−3031. [4] Poulain et al., 2022, Env. Sci. & Tech 56
: 14817-14827 [5] Wang et al., 2022, Environ. Sci. Technol. 2022, 56, 9. [6]
Charlet et al., Geochim. Cosmochim. Acta 71: 5731-49. [7] Kirsch et al., 2008,
Mineral Mag, 72, 185-189. [8] Kirsch et al, 2011, Environ. Sci. Technol. 45 :
7267–7274

Keywords: oxyanion; redox

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  • Invited lecture (Conferences)
    Goldschmidt Conference 2023, 09.-14.07.2023, Lyon, France

Permalink: https://www.hzdr.de/publications/Publ-36664


Coordination chemistry of the early actinides

März, J.

Abstract

The actinides (An) are located at the bottom of the periodic table. These elements are exclusively radioactive, highly chemo-toxic, and play an important role in chemical engineering and environmental science related to the nuclear industry or nuclear waste repositories. In contrast to the strongly shielded 4f electrons of the lanthanides, 5f electrons of particularly the early An are found to participate in bonding, e.g. to organic ligands. Another characteristic of the An is their huge variety of possible oxidation states, typically ranging from +II to +VII for early actinides, making their chemistry complex but interesting. A suitable approach to explore fundamental physico-chemical properties of the actinides is to study series
of isostructural An compounds in which the An is in the same oxidation state. Observed changes in e.g. the binding situation or magnetic effects among the An series may deliver insight into their unique electronic properties mainly originating from the f-electrons. A question still remaining in the field of An chemistry is the degree of “covalency” in compounds across the actinide series, which may be addressed by systematic studies on series of An compounds, including transuranium (TRU) elements.
We investigate the coordination chemistry of low-valent actinides using organic N-, O-, or S-donor ligands. Information on covalency trends as well as mutual ligand influences can be obtained by the analysis of solid-state structures derived by SC-XRD in combination with quantum chemical calculations (QCC) and high-energy-resolution fluorescence detection X-ray absorption near edge spectroscopy (HERFD-XANES). In solution, NMR spectroscopy permits to draw conclusions about the complex speciation in solution, the intrinsic magnetic properties of the actinides, or subtle changes in covalency in the ligand-actinide-bonding.

Keywords: actinides; coordination chemistry; covalency; bonding analyses

  • Invited lecture (Conferences)
    AC-Kolloquium, 18.01.2023, Leipzig, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36663


Reductive immobilization of 99Tc(VII) by pyrite and marcasite

Rodríguez, D. M.; Mayordomo, N.; Brendler, V.; Scheinost, A.; Schild, D.; Müller, K.

Abstract

99Tc is a fission product with a long half-life of 2.14 × 105 years. Its migration and bioavailability strongly depend on its oxidation state and speciation in aqueous solution. Under oxidizing conditions, Tc mainly exists as pertechnetate, TcVIIO4, a highly water-soluble anion with s negligible sorption to most minerals. Under reducing conditions, TcIV prevails, whose main species, TcO2 xH2O, is a polymer of low solubility. As the presence of reductants like Fe2+ in the near-field of a nuclear waste repository is expected due to canister corrosion, several studies consider 99TcVII reductive immobilization by minerals containing reductant moieties, such as magnetite (FeIIFe2IIIO4) or mackinawite (FeS) [1]

Pyrite (cubic FeS2) is a redox sensitive sulfide mineral that has been identified as a good sorbent for TcVII from soil and groundwater [2]. Under repository conditions, both pyrite and marcasite (orthorhombic FeS2) are expected to form by corrosion processes and microbial interaction [3]. Moreover, both iron sulfides are also accessory minerals in granitic and argillaceous rocks. Therefore, reliable data on 99TcVII retention by both minerals and their mixtures is relevant for the safe disposal of nuclear waste.

We have studied the Tc retention by pure pyrite and by a mixture of marcasite and pyrite (60:40) using a combination of batch experiments and spectroscopy (Raman microscopy, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy) at pH 6 and 10. [4, 5]. We confirm the 99TcVII reduction and subsequent 99TcIV retention on the mineral surfaces and shed new light on different retention mechanisms for pyrite and marcasite at pH 10.

We acknowledge funding from the German Federal Ministry of Economic Affairs and Energy (BMWi) for VESPA II project (02E11607B), and from the German Federal Ministry of Education and Research (BMBF) for the NukSiFutur TecRad young investigator group (02NUK072).

[1] Yalçıntaş E, et al. 2016 Dalton Trans. 45 17874
[2] Huo L, et al. 2017 Chemosphere 174 456
[3] Roberts W M B, et al. 1969 Mineralium Deposita 4 18
[4] Rodríguez D M, et al. 2020 Environ. Sci. Technol. 54 2678
[5] Rodríguez D M, et al. 2021 Chemosphere 281 130904

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  • Poster
    Goldschmidt 2023 Conference, 09.-14.07.2023, Lyon, France

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Proton dosimetry in a magnetic field: measurement and calculation of correction factors for a plane-parallel ionization chamber

Gebauer, B.; Baumann, K.-S.; Fuchs, H.; Georg, D.; Oborn, B.; Looe, H.-K.; Lühr, A.

Abstract

Purpose: In magnetic resonance imaging-integrated proton therapy (MRiPT), the magnetic field-dependent change in the dosage of ionization chambers is considered by the correction factor k ⃗ B,M,Q, which needs to be determined experimentally or computed via Monte Carlo (MC) simulations. In this study, k ⃗B,M,Q was both measured and simulated with high accuracy for a plane-parallel ionization chamber at different clinical relevant proton energies andmagnetic field strengths.

Material&Methods: The dose-response of the Advanced Markus chamber (TM34045, PTW, Freiburg, Germany) irradiated with homogeneous 10×10 cm2 mono-energetic fields, using 103.3, 128.4, 153.1, 223.1, and 252.7 MeV proton beams was measured in a water phantom placed in the magnetic field (MF) of an electromagnet with MF strengths of 0.32, 0.5, and 1 T. The detector was positioned at a depth of 2 g/cm2, with chamber electrodes
parallel to the MF lines and perpendicular to the proton beam incidence direction. The measurements were compared with TOPAS MC simulations utilizing COMSOL-calculated 0.32, 0.5, and 1 T MF maps of the electromagnet. k ⃗B,M,Q was calculated for the measurements for all energies and MF strengths based on the equation: k ⃗B,M,Q = MQ/M ⃗ BQ , where MQ and M ⃗ BQ were the temperature and air-pressure corrected detector readings with and without the MF, respectively. MC-based correction factors were determined as k ⃗B,M,Q = Ddet/D ⃗ Bdet , where Ddet and D ⃗ Bdet were the doses deposited in the air cavity of the ionization chamber model without and
with the MF, respectively.

Results: The detector showed a reduced dose-response for all measured energies and MF strengths, resulting in experimentally determined k ⃗B,M,Q values larger than unity. k ⃗B,M,Q increased with proton energy and MF strength, except for 0.5 T and 252.7 MeV. Overall, k ⃗B,M,Q ranged between 1.0065 and 1.0205 for all energies and MF strengths examined and the strongest dependence on energy was observed at 1 T. The MC simulated k ⃗B,M,Q values for all MF strengths showed a good agreement with the experimentally determined correction factors with a maximum deviation of 0.6% and trends within their standard deviations.

Conclusion: For the first time, measurements and simulations were compared for an Advanced Markus chamber for proton dosimetry within MFs. For all MF strengths, there was a good agreement of k ⃗B,M,Q between experimentally determined and MC calculated values in this study. By benchmarking the MC code for the calculation of k ⃗B,M,Q it can be used to calculate k ⃗B,M,Q for various ionization chamber models, MF strengths and proton energies to generate the data needed for a dosimetry protocol for MRiPT.

Keywords: dosimetry; MC simulation; advanced Markus chamber; proton; magnetic fields; MR integrated proton therapy; MRiPT

Permalink: https://www.hzdr.de/publications/Publ-36661


Results of a round robin test on surface energy analysis of silica and lactose by inverse gas chromatography

Sandbrink, J.; Duempelmann, R.; Meyer, R.; Adamska, K.; Strzemiecka, B.; Enke, D.; Rudolph, M.; Brendlé, E.

Abstract

Inverse gas chromatography (IGC) has become a popular technique for the analysis of particulate materials. By injecting certain probe molecules through a column containing the sample as the stationary phase and measuring the retention time of said probe molecules, information on a range of different physicochemical properties, such as surface energy or Hansen-solubility parameters can be obtained. A proper understanding of these physicochemical properties is significant for many industrial processes (e.g. formulation, miscibility of polymer blends, agglomeration), as said processes are often driven by surface properties.
Though, IGC analysis has many benefits and is widely used nowadays, the comparability of results that are reported and measured by different operators using different IGC devices has not been investigated yet. Therefore, a round robin test was conducted, where eight organisations analysed two standard materials, silica and lactose, according to a jointly defined protocol using IGC devices that either have a valve-based or a syringe-based dosing system. The results are evaluated based on standard IGC theories and the same mathematical operations are applied to all datasets in order to obtain the specific retention volume and the dispersive surface energy component for the two materials. The resulting values of the calculated parameters vary quite significantly, which is a rather unexpected and a very unpleasant finding for this highly sensitive analytical device. Measurements that are conducted individually by the same operator on the same IGC device report similar results, whereas results obtained by different operators with different types of IGC devices are significantly different. Potential factors for the differences, such as the injected quantity of the probe molecules, are presented and discussed.
This round robin test therefore raises some questions on the reproducibility of results obtained via inverse gas chromatography. Furthermore, it demonstrates the need for a standard powder and protocol in order to have a common ground for an objective judgment of results.

Keywords: Inverse gas chromatography; surface energy; physicochemical properties; silica; lactose

  • Poster
    Jahrestreffen der DECHEMA-Fachgruppen Kristallisation, Grenzflächenbestimmte Systeme und Prozesse und Mechanische Flüssigkeitsabtrennung, 09.-10.03.2023, Frankfurt, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36660


Redox reactivity of selenium (VI) in the presence of Fe(II) and S(−II) bearing mineral phases under the conditions of Callovo-Oxfordian pore water

Saini, D.; Fernandez-Martinez, A.; Jordan, N.; Madé, B.

Abstract

⁷⁹Se with a half-life of 3.27 × 10⁵ y [1] is presently considered as a key mobile radionuclide for the disposal of spent fuel and high-level waste [2]. The solubility of selenium (Se) is largely controlled by its oxidation state, and hence depends on the redox conditions present in soils, sediments, bedrock and aquifers. The −II, −I, and 0 oxidation states are commonly predominant in “reducing” anoxic environments, while the +IV and +VI states predominate in more “oxidizing” environments [2]. The interactions with Fe(II) and S(–II)-bearing redox active solids- mediate the oxido-reduction kinetics of Se oxyanions, playing an important role in the control of Se speciation [3]. Regarding Se(VI), it was found to be metastable (far from thermodynamic equilibrium) and potentially selenium could coexist in different oxidation states in the Callovo-Oxfordian pore waters [4]. The reduction of Se(VI) by magnetite, much slower than for Se(IV), include different steps (adsorption, reduction to Se(IV), and further reduction to less soluble Se phases: Se⁰(s), FeSe₂(s), FeSe(s)), each of them imposing a kinetic barrier for the whole reduction process. At present it is not clear whether the Se(VI) initial adsorption or its reduction to Se(IV) are concomitant or not, and extra work needs to be done in this direction to establish the reduction pathway. Furthermore, little is known about the potential competition with ubiquitous ions in porewater such as carbonate or sulfate and especially about their capability to limit the contact of selenate molecules with the Fe(II)-bearing solids, and thus to inhibit the electron transfer.
The redox reactions Se(VI) with magnetite and pyrite under neutral pH conditions will be deciphered at both macroscopic and molecular levels by combining batch sorption studies and advanced spectroscopic techniques (XAS, XPS). In addition, the influence of sulfate ions will be investigated.

[1] Jörg, G. et al., Appl. Radiat. Isot. (2010), 68 (12), 2339−2351.
[2] Fernandez-Martinez, A. and Charlet, L., Rev. Environ. Sci. Biotechnol. (2009), 8, 81–110.
[3] Scheinost, A. C. et al., J Contam Hydrol (2008), 102, 228-45.
[4] Savoye, S. et al., Appl. Geochemistry (2021), 128, 104932.

  • Contribution to proceedings
    Goldschmidt2023, 09.-14.07.2023, Lyon, France
  • Poster
    Goldschmidt2023, 09.-14.07.2023, Lyon, France

Permalink: https://www.hzdr.de/publications/Publ-36659


Wave Function Extent in multilayer van der Waals Heterostructures: A First-Principles Study

Umm-E.-Hani; Muhammad, S. R.; Kuc, A. B.

Abstract

A good understanding of interlayer coupling is crucial to designing novel van der Waals heterostructures. The present study examines two types of multilayer heterostructures based on 2D transition-metal dichalcogenides (TMDCs). ABC or ABBC stackings consist of three layers (A - MoS2, B - MoSe2, C - WSe2). By doing so, MoSe2 spatially separates the electron layer (MoS2) from the hole layer (WSe2). TMDCs are stacked in one of three ways in the second type: ABA, ABBA, or AABAA. Depending on stoichiometry, the electrons or holes are localized in the middle part of the heterostructure or delocalized to the outer layers. The majority of the materials studied here are direct gap semiconductors with transitions at K. A type II band alignment is found in all of them. We predict that indirect excitons will be evident in all materials.

  • Poster
    Chem2Dmat2023, 15.-18.05.2023, Bologna, Italy

Permalink: https://www.hzdr.de/publications/Publ-36658


Reduction of pertechnetate by magnetite - influence of pH and time

Zimmermann, T.; Faria Oliveira, A.; Mayordomo, N.; Scheinost, A.

Abstract

Magnetite is arguably the most relevant corrosion product when steel canisters corrode anaerobically in future deep geological radioactive waste repositories. 99Tc is of great concern for the safety assessment of these repositories, due to its long half-life (t1/2 = 2.1∙105 years). Under oxidative conditions Tc forms an anionic species, pertechnetate (TcVIIO4−), which is highly mobile due to its high solubility and weak sorption on most minerals. Under anaerobic conditions, TcVII can be reduced to TcIV, which strongly interacts with minerals by sorption, structural incorporation and formation of insoluble oxides like TcO2. FeII-minerals, and among them magnetite, have shown to effectively reduce pertechnetate and play thereby a critical role.[1]
Previous studies by Yalcintas et al.[2] suggested that TcVII reduction by magnetite resulted in the precipitation and surface adsorption of TcO2-like oligomers at pH 9, i.e. close to the pH of magnetite solubility minimum. In contrast at pH 6-7, the reduction resulted in a partial incorporation of TcIV in octahedral Fe-sites of magnetite.[3] Our initial working hypothesis was that the incorporation is linked to magnetite solubility. To test this, we investigated Tc reaction with magnetite nanoparticles in a wide range of pH (3 - 13), reaction time (1 - 210 days) and varied initial Tc concentration (μM - mM).
To characterize the oxidation state of Tc and its molecular structure, we employed a range of methods including Tc K-edge (21 044 eV) X-ray absorption spectroscopy (XAS) at the Rossendorf Beamline at the ESRF in Grenoble. XANES analysis revealed the predominance of TcIV at all evaluated pH values, supporting that reductive Tc immobilization is the main retention mechanism. EXAFS analysis suggests that two species are formed. At pH 5 and short equilibration times, Tc is retained by forming TcO2∙xH2O polymers, showing the recently reported “zig-zag-chain” structure[4]. In contrast, TcIV substituted magnetite forms within a few hours at pH 7 and 10. At pH 5, it forms only after a few days with the proportion of the Tc-magnetite phase growing at the expense of the TcO2∙xH2O polymers. Therefore, across the pH range 5 to 10, Tc-magnetite seems to be the thermodynamically preferred phase. The initial formation of TcO2∙xH2O polymers at low pH seems to be linked to the release of Fe2+ from magnetite (reductive maghemitization)[5], which leads to substantial Fe2+ concentrations in solution due to the lacking re-adsorption at this pH. The mechanism behind the fast incorporation of TcIV in magnetite, now observed for the first time within days across a wide pH range, remains unsolved. The structural stability of cubic spinel magnetite and the absence of strong evidence for structural uptake of other elements with similar coordination number and ionic
Fig. 1: Schematic process of the interaction of pertechnetate (TcVIIO4−) with magnetite radius like Co, Ni and other 3d metals, point to a complex coupled sorption/redox/incorporation mechanism.
In order to better understand the Tc incorporation into by magnetite, we also conducted density functional theory (DFT) calculations using the PBE[6] functional implemented in AMS/BAND 2022[7], with full optimization of atomic coordinates and lattice parameters. For the finite structures, solvent effects were included with the COSMO[8]. Three charge compensation mechanisms were considered. The calculated incorporation energies and comparison of the Tc coordination structure with experimental EXAFS data indicate that Tc incorporation is most likely to occur either by substitution of two octahedral FeIII sites with a TcIV/FeII pair (Fig. 2, left), or by substitution of two FeII sites with a single TcIV, thus forming a vacancy (Fig. 2, right). The last mechanism, where three TcIV replace four octahedral FeIII (Fig. 2, center), could be excluded.

Keywords: magnetite; technetium; XAFS; ROBL; redox

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  • Lecture (Conference)
    Migration Conference, 24.-29.09.2023, Nantes, France

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Understanding uranium fate in wetland soils: a speciation and labile behavior study in the former extraction mine of Rophin (France)

Nivesse, A.-L.; Landesman, C.; Arnold, T.; Sachs, S.; Stumpf, T.; Scheinost, A.; Coppin, F.; Fevrier, L.; Den Auwer, C.; Gourgiotis, A.; Del Nero, M.; Montavon, G.

Abstract

Uranium (U) mining and milling activities, as well as mineral processing plants, raise environmental concerns due to the possible release of radioactive and other potentially toxic elements. To understand their fate in the environment and evaluate their potential impact, the main scientific challenge calls for identifying their solubility, mobility and bioavailability in the environment. Around former U mining and processing plants, wetlands prove to be specific zones with significant amounts of U. This is partly explained by the reduction of the mobile U(VI) into U(IV) due to strongly reducing conditions related to the microbial activity and/or by complexation with the organic matter occurring with high concentrations in wetlands.
At the center of the ancient mining district of Lachaux in France (45.994°N, 3.596°E), the site of Rophin (within the ZATU: Uranium Working Zone = Long Term Socio-Ecological Research Tool of CNRS, Fig.1.a) is characterized by a wetland area with large U concentrations up to 16 g.kg-1 of dry mass of soil [1]. Several cross-analyses indicate that U was transported in particulate forms into the wetland during the exploitation of U(VI) phosphate minerals [1]. The Rophin site therefore provides the opportunity to study the stability of these U minerals over almost 70 years in a non-manipulated wetland since the closure of the mine. In this context, the main challenge is to describe the behavior of U (and decay products of interest) in the wetland using a predictive model that combines transport and chemical speciation. The overall adopted scientific approach is to propose a mechanistic description of the mobility of these elements, from the molecular scale (speciation) to in natura behavior (lability), by coupling field investigations and laboratory experiments.
A simplified three-layer model describes the soil profile of the Rophin wetland, with variable U concentrations and specific physico-chemical soil properties (Fig.1.b). Analyses carried out by X-absorption spectroscopy on in natura soil samples mainly indicate the presence of an adsorbed form of U(IV) in the highly contaminated layer, while both U(IV) and U(VI) are identified in the organically rich part at the surface. Additional SEM-EDX and μ-XRF mapping measurements also indicate that U minerals transported into the wetland were partially dissolved and re-adsorbed in soils.
The objective was to determine which fraction is finally labile, i.e. the fraction that is adsorbed and whose resupply in solution is rapid. This was assessed by desorption experiments under representative site conditions with two complementary approaches [2,3]. Overall, the available fraction is very low (3 to 10 % for the highly contaminated layer and less than 1% for the surface layer) and is characterized by distribution coefficient (Kd) values of the order of 102 L.kg-1. These results were then compared with field data using DGT/DET techniques coupling (Diffusive Gradient in Thin-films/ Diffusive Equilibrium in Thin-Films) [4]. We found an available fraction in the whitish zone, which is rapidly eliminated with time, whereas a labile U fraction is almost undetectable in the surface layer. Combined with time-dependent deployment DGT/DET coupling, results highlighted the predominance of a kinetic parameter and thus, the expected key role of the organic matter in the U mobile behavior in the surface soil.
This study provides access to the input data (labile quantity and (Kd) values) for the establishment of a reactive transport model at the scale of the Rophin mining-affected wetland, but also allows to determine significant information on U interactions in soils. As such, this multi-scale and interdisciplinary study contributes to the improvement of the global understanding of U migration and fate in wetland soils.

Keywords: uranium; soils; ROBL; mining

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  • Lecture (Conference)
    Migration Conference, 24.-29.09.2023, Nantes, France

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From FineFuture to FINEST towards a more sustainable circular economy

Dirlich, S.; Renno, A.; Engelhardt, J.; Rudolph, M.; Stemmermann, P.; Heipieper, H.

Abstract

The EU-funded H2020 project FineFuture successfully tackled the recovery of fine particles for an increased resource efficiency, and an improved pneumatic flotation technology was one of the key outcomes with the very realistic option of bringing it to industry. Though being potentially suitable for secondary material as well, the focus was on primary ores such as manganese, magnesite or iron. Nevertheless, feeding the pneumatic flotation cell with tailings material was also conducted in some experiments, and resulted in satisfactory recovery rates of the target elements.
However, due to resource depletion and the paradigm of climate-neutrality economy needs to be transformed into a more circular one, making use of sustainable value chains and keeping resources longer in the loop. Therefore, the research goes further with the project FINEST, and tackles finest particulate matter of anthropogenic origin such as shredder waste from WEEE or cars, fine ashes, etc. The target elements considered from these waste materials are microplastics, mineral additives and disperse metals. The idea is to combine different waste streams by blending them in order to stimulate improved process behavior, and an increase of the recovery rate of valuable elements such as copper, iron etc. Most of the waste streams considered in FINEST are currently not utilized, resulting in a great benefit for circularity and simultaneously reducing environmental harm through the reduction of the amount of material that needs to be disposed of. The unavoidable residuals are treated in a way that all compounds are inert, and allow for a safe disposal.
The project is largely oriented towards transdisciplinarity, and the FINEST Research School is additionally embedded into the research project. The school aims to train postgraduate students in a structured way to allow them to become transfer experts in resource management. While offering training at industry during the PhD phase, the school follows the concept of “transfer via brains“, which means to aim for an excellent education of the PhD’s, who will enter industry afterwards with the goal to manage a transformation from inside into more circular thinking.

Keywords: finest particles; resource recovery; sustainable value chains; circular economy; microplastics; mineral additives; disperse metals

  • Open Access Logo Lecture (Conference)
    World Resources Forum'23, 04.-6.9.2023, Genf, Schweiz

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From FineFuture to FINEST: Resource Supply for the Energy Transition and Sustainable Value Chains

Dirlich, S.; Schlosser, D.; Stapf, D.; Renno, A.; Gutzmer, J.

Abstract

One of the biggest threats to humankind and the planet is the climate change that is propelled by excessive carbon dioxide emissions mainly being generated through combustion of fossil fuels in industry, transportation, building, etc. In order to keep the increase of the global temperature below 2K compared to pre-industrialization level, climate-neutrality becomes more and more important for nations, societies, regions, cities and companies in response to this development. In addition, a sustainable circular economy that keeps material streams in the loop as far as possible contributes to this goal. However, the transformation of the society and economy towards more sustainability requires a vast amount of resources in itself. Though resource depletion may actually not really be a challenge for many elements, in particular those elements that are required for high technology applications such as batteries for electro mobility, wind turbines, etc. are scarce, and might become even scarcer in view of the pursued expansion of sustainable and climate-neutral technologies. This is the case for example for lithium as an important raw material for batteries, but also for rare earth elements like neodymium that are required for magnets in wind turbines.
In addition, the extraction of primary ores becomes also more and more difficult due to decreasing concentrations of valuable minerals in the ore bodies in turn leading to even larger amounts of mining waste compared to the recovery of the target element. Often, a considerable part of the minerals cannot be recovered as the particles are too fine for the conventional processing technologies currently in place. In order to tackle this challenge, the Horizon 2020 project FineFuture was conducted in which experts from all over Europe collaborated to find ways to unlock the fine-grained mineral and critical raw materials resources through innovative technologies and concepts for fine particle flotation. Beside advancements in the fundamental understanding of the underlying processes in the interphases as well as the modelling of the particle flows, the pneumatic flotation technology was improved through a new design and more suitable selection of frothers and collectors resulting in higher recovery rates for certain minerals such as manganese and magnesite.
Current research going on is intended to utilize and manage finest particulate matters of anthropogenic origin. The types of finest materials considered in the FINEST project jointly conducted by HZB, HZDR, KIT, UFZ, TUBAF and UG are microplastics, mineral additives and disperse metals, which are found in waste streams such as plastics waste, external thermal insulation composite systems, light-weight shredder fractions (e.g. from electronic scrap and/or automotive recycling), etc.
The sub-project FINEST Microplastics deals with biotechnological solutions for the utilization of the microplastics fraction. Biocatalysts are to convert the plastics fraction to yield specific mono-/oligomers for product synthesis, microbial biomass amenable to further microbial fermentation and inert residues for a safe deposition.
The sub-project FINEST Mineral Additives is dedicated to finest minerals with the aim to recover mineral additives like fillers, flame retardants, pigments or heat stabilizers during chemical recycling processes. By means of pyrolysis, part of the mineral additives from external thermal insulation composite systems shall be recovered while non-separable additives shall be safely stored in recycling cement and low-grade plastics may be utilized by feeding them back into the plastics fraction.
The sub-project FINEST Disperse Metals targets at a blending and agglomeration of complex residues composing of finest particles. The pellets produced from the blended waste shall be further processed through thermal treatment in a furnace aiming at the recovery of the metallic content. The remaining residues shall be disposed of in an inert form.
These innovative approaches need to be assessed in terms of their technological, ecological, economic, and social impact in comparison to the conventional processing, but also in comparison to a mere storage, which is regularly the case for the finest particle waste up-to-date.
Finally, the transdisciplinary approach of the project shall enable a transformation of industry through “transfer via brains” in order to contribute to a circular economy and enable more sustainable value chains.

Keywords: finest particles; resource recovery; sustainable value chains; circular economy; microplastics; mineral additives; disperse metals

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

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Data publication: Small-angle neutron scattering study of neutron-irradiated and post-irradiation annealed VVER-1000 reactor pressure vessel weld material

Ulbricht, A.; Dykas, J.; Chekhonin, P.; Altstadt, E.; Bergner, F.

Abstract

messdaten und auswertedaten

Keywords: reactor pressure vessel; weld; neutron irradiation; annealing; small-angle neutron scattering; Vickers hardness; solute-rich clusters; recovery

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Data publication: Experimental characterization of four-magnon scattering processes in ferromagnetic conduits

Hula, T.

Abstract

All Raw and Processed Data + written Thesis. Data and Figures are stored in the 'Figures_and_Data' Directory. Experimental Measurements were done by means of BLS Microscopy (group of H. Schultheiß at HZDR). Micromagnetic Simulations were done at the Hemera Cluster (Dr. A. Kakay at HZDR). Data Analysis was done in Python or Jupyter Notebooks (Open Source). All scripts are included. Graphics were done using OmniGraffle and Blender. Plotting was done using Python and 'Plot2' (Mac Only!). All Files/Data/Skripts are sorted by Figure! The entire Latex Package is stored under 'Thesis_Hula' - Dissertation.tex is the main file and shows all required dependencies.

Keywords: Magnonics; Spin waves; Brillouin spectroscopy; light scattering; nonlinear phenomena; scattering

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Experimental characterization of four-magnon scattering processes in ferromagnetic conduits

Hula, T.

Abstract

PhD Thesis:

Experimental characterization of four-magnon scattering processes in ferromagnetic
conduits

Keywords: Magnonics; Spin waves; Brillouin spectroscopy; light scattering; nonlinear phenomena; scattering

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  • Doctoral thesis
    TU Chemnitz, 2023
    Mentor: Prof. Olav Hellwig / Dr. Helmut Schultheiß
    140 Seiten

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Clinical Significance of Tumor-Infiltrating Conventional and Plasmacytoid Dendritic Cells in Pancreatic Ductal Adenocarcinoma

Plesca, I.; Benešová, I.; Beer, C.; Sommer, U.; Müller, L.; Wehner, R.; Heiduk, M.; Aust, D.; Baretton, G.; Bachmann, M.; Feldmann, A.; Weitz, J.; Seifert, L.; Seifert, A. M.; Schmitz, M.

Abstract

Dendritic cells (DCs) play a key role in the orchestration of antitumor immunity. Activated DCs efficiently enhance antitumor effects mediated by natural killer cells and T lymphocytes. Conversely, tolerogenic DCs essentially contribute to an immunosuppressive tumor microenvironment. Thus, DCs can profoundly influence tumor progression and clinical outcome of tumor patients. To gain novel insights into the role of human DCs in pancreatic ductal adenocarcinoma (PDAC), we explored the frequency, spatial organization, and clinical significance of conventional DCs type 1 (cDC1s) and type 2 (cDC2s) and plasmacytoid DCs (pDCs) in primary PDAC tissues. A higher density of whole tumor area (WTA)- and tumor stroma (TS)-infiltrating cDC1s was significantly associated with better disease-free survival (DFS). In addition, an increased frequency of intraepithelial tumor-infiltrating cDC2s was linked to better DFS and overall survival (OS). Furthermore, an increased density of WTA- and TS-infiltrating pDCs tended to improve DFS. Moreover, a higher frequency of WTA- and TS-infiltrating cDC1s and pDCs emerged as an independent prognostic factor for better DFS and OS. These findings indicate that tumor-infiltrating DCs can significantly influence the clinical outcome of PDAC patients and may contribute to the design of novel treatment options that target PDAC-infiltrating DCs.

Keywords: dendritic cells; neoadjuvant chemotherapy; pancreatic cancer; tumor microenvironment

Permalink: https://www.hzdr.de/publications/Publ-36650


Curvilinear Magnetic Architectures for Biomedical Engineering

Baraban, L.; Huang, T.; Chen, X.; Santiago Herrera Restrepo, R.; Ignés Mullol, J.; Puigmartí-Luis, J.; Pané, S.

Abstract

The field of autonomous motile micro/nanomotors that can propel in the liquid environment strongly benefits from the use of magnetic materials, winning in the long-time deterministic locomotion and controllability of such microscopic objects. This chapter reviews the applications of curved magnetic micro/nanostructures to be employed for biomedical and environmental applications. In this respect, after introducing the basic principle and examples of the self-propelled micro-objects, we further focus here on the locomotion of the magnetically decorated microscopic objects and the influence of their shape on the character and pattern of the motion. Namely, we consider the properties of magnetically capped spherical Janus particles, rod-like, tubular, and other asymmetric objects, e.g., microhelices, with magnetic functionalization. Finally, we describe the applications of such magnetic objects in environmental remediation, biosensing and drug delivery, etc.

  • Book chapter
    Denis D. Sheka, Denys Makarov: Curvilinear Micromagnetism, Springer Cham: Springer, 2023, 978-3-031-09088-2
    DOI: 10.1007/978-3-031-09086-8

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Molecular scale understanding of Ni2+ adsorption on swelling clay minerals

Stotskyi, V.; Di Lorenzo, F.; Marques Fernandes, M.; Krack, M.; Scheinost, A.; Lanson, M.; Lanson, B.; Churakov, S. V.

Abstract

Sorption of hazardous metals on clay minerals is a key process contributing to the safety of repository sys-tems. The existence of high- and low-affinity adsorption sites on smectites edge surfaces, responsible for met-als uptake has been revealed in previous studies [1,2]. The exact molecular nature of these adsorption sites has not been fully resolved.
Similar to the adsorption of Ni2+ on montmorillonite [1], Ni2+ on saponite shows a non-linear adsorption be-havior, which, by analogy, suggests the existence of strong and weak sorption sites (Fig.1). Based on the sorp-tion isotherms obtained on saponite, self-oriented clay films were prepared, with Ni loadings corresponding to adsorption dominated by strong and weak sites, and then polarized Ni K-edge EXAFS spectra were recorded.
For samples with low Ni2+ loadings (below 4 mmol/kg), P-EXAFS results confirmed the existence of strong sorption sites. An increase of Ni loading (up to 40 mmol/kg) leads to decreasing in Ni-Mg bond length and an increase in Ni-Si coordination number, indicating the formation of a secondary phase. The exact structure of the new phase is still under evaluation, but this solid phase will certainly mask Ni sorbed to weak sites.
The molecular structure of cations adsorbed on the water-edge interfaces for the most stable surfaces was modeled using ab initio MD, which enable us to obtain a theoretical estimation of the free energies of Zn-Ni cation exchange reactions between weak and strong sites on (100) and (130) edges of saponite. Theoretical values obtained for Zn-Ni exchange are equal to 13.5±0.4 and 5.50±0.03 kJ/mol for (100) and (130) surfaces, respectively. These results are in a good agreement with experimental results for montmorillonite (9.1 kJ/mol) – a trustworthy proxy and suggest a stronger affinity of Zn to strong sites than Ni.

Keywords: Montmorillonite; Saponite; Nickel; Sorption; ROBL

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Permalink: https://www.hzdr.de/publications/Publ-36648


Thick as thieves: Antimony sequestration during ferrous iron oxidation

Wegner, L.; Scheinost, A.; Peiffer, S.; Hockmann, K.

Abstract

The geochemical behavior of antimony (Sb), a priority pollutant of increasing concern, is closely linked to the redox cycling of iron (Fe). Microbial reduction of Fe(III) oxides and production of soluble Fe(II) under anoxic conditions has been shown to release co-associated Sb (occurring as Sb(V) and/or Sb(III)). In redox-dynamic environments, Fe(II) can be re-oxidized and precipitate as Fe(III) oxides. The extent to which these processes affect Sb mobility, however, is still poorly understood and likely depends on an array of factors such as pH, Sb species and the nature of the newly formed Fe(III) oxides.

Here, we investigated the effect of Fe(II) oxidation on Sb sequestration and on the mineralogy of the resulting Fe(III) precipitates in a pH range typical of Sb-contaminated systems (i.e. pH 6, 6.5, and 7). To initiate the oxidation reaction, 0.5 mmol L-1 Fe(II) was added to an oxygen-saturated electrolyte solution containing 0 – 50 µmol L-1 Sb(V) or Sb(III). Changes in aqueous Sb and Fe(II) were tracked during the experiments, and solid phase samples were collected at the end of the oxidation reaction for characterization by diffractometric, spectroscopic, and microscopic techniques.

Iron(II) oxidation kinetics and Sb sequestration were a function of pH and Sb species, with Sb(III) retarding the oxidation reaction. In the absence of Sb, Fe K-edge extended X-ray absorption fine structure (EXAFS) analysis revealed lepidocrocite as the only solid-phase product. In presence of Sb, feroxyhyte and goethite formed instead of lepidocrocite. The shift in Fe oxide assemblage was more pronounced when Sb was present as Sb(V) and at a lower pH. Antimony EXAFS analyses showed an almost complete oxidation of Sb(III) to Sb(V) followed by the incorporation of Sb(V) into the structure of the Fe oxides precipitates.

Our results allow for a better understanding of Sb geochemistry in redox-dynamic environments as they demonstrate that Sb itself can influence the pathways of secondary Fe oxide formation. Our study also provides important information for the development of adequate remediation practices of Sb-contaminated soils and sediments that are subject to changes in redox conditions as induced by flooding or waterlogging.

Keywords: Antimony; EXAFS; ROBL; Iron oxides; lepidocrocite

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  • Open Access Logo Lecture (Conference)
    Goldschmidt Conference 2023, 09.-14.07.2023, Lyon, France

Permalink: https://www.hzdr.de/publications/Publ-36647


Small-angle neutron scattering study of neutron-irradiated and post-irradiation annealed VVER-1000 reactor pressure vessel weld material

Ulbricht, A.; Dykas, J.; Chekhonin, P.; Altstadt, E.; Bergner, F.

Abstract

Post-irradiation annealing of neutron-irradiated reactor pressure vessel steels is a matter of both technical and scientific interest. Small-angle neutron scattering (SANS), while being sensitive to nm-sized irradiation-induced solute-atom clusters, provides macroscopically representative and statistically reliable measures of cluster volume fraction, number density and size. In the present study, SANS was applied to uncover the size distribution of clusters in as-irradiated samples of a VVER-1000 weld and their gradual dissolution as function of the post-irradiation annealing temperature. The same samples were used to measure Vickers hardness. The results are consistent with Mn-Ni-Si-rich clusters of less than 2 nm radius to be the dominant source of both scattering and hardening. Annealing gave rise to small but significant partial recovery at 350 °C and almost complete recovery at 475 °C. The dispersed-barrier hardening model was applied to bridge the gap between the characteristics of nano-features and macro-hardness.

Keywords: reactor pressure vessel; weld; neutron irradiation; annealing; small-angle neutron scattering; Vickers hardness; solute-rich clusters; recovery

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Permalink: https://www.hzdr.de/publications/Publ-36646


Field-Tunable Berezinskii-Kosterlitz-Thouless Correlations in a Heisenberg Magnet

Opherden, D.; Tepaske, M. S. J.; Bärtl, F.; Weber, M.; Turnbull, M. M.; Lancaster, T.; Blundell, S. J.; Baenitz, M.; Wosnitza, J.; Landee, C. P.; Moessner, R.; Luitz, D. J.; Kühne, H.

Abstract

We report the manifestation of field-induced Berezinskii-Kosterlitz-Thouless (BKT) correlations in the weakly coupled spin-1/2 Heisenberg layers of the molecular-based bulk material [Cu(pz)2(2-HOpy]2)(PF6)2. At zero field, a transition to long-range order occurs at 1.38 K, caused by a weak intrinsic easy-plane anisotropy and an interlayer exchange of J´/kB ≈ 1 mK. Because of the moderate intralayer exchange coupling of J/kB = 6.8 K, the application of laboratory magnetic fields induces a substantial XY anisotropy of the spin correlations. Crucially, this provides a significant BKT regime, as the tiny interlayer exchange J0 only induces 3D correlations upon close approach to the BKT transition with its exponential growth in the spin-correlation length. We employ nuclear magnetic resonance measurements to probe the spin correlations that determine the critical temperatures of the BKT transition as well as that of the onset of long-range order. Further, we perform stochastic series expansion quantum Monte Carlo simulations based on the experimentally determined model parameters. Finite-size scaling of the in-plane spin stiffness yields excellent agreement of critical temperatures between theory and experiment, providing clear evidence that the nonmonotonic magnetic phase diagram of [Cu(pz)2(2-HOpy]2)(PF6)2 is determined by the field-tuned XY anisotropy and the concomitant BKT physics.

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  • High Magnetic Field Laboratory (HLD)

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Permalink: https://www.hzdr.de/publications/Publ-36645


Uranium(VI) reduction by iron- and sulfate-reducing bacteria in pure culture and in artificial multispecies bio-constructs

Hilpmann, S.; Jeschke, I.; Deev, D.; Zugan, M.; Lapanje, A.; Rijavec, T.; Steudtner, R.; Hübner, R.; Schymura, S.; Cherkouk, A.

Abstract

The microbial reduction of U(VI) to U(IV) can decrease the mobility of U contaminants in the environment and may have a significant impact on the safety of a nuclear waste repository, as well as, the potential to serve as a component in bioremediation strategies for U-contaminated environments. In this study, we show significant differences in the reduction mechanisms for iron- and sulfate-reducing bacteria, highlighting the importance of investigating microbe-uranium interaction of different bacterial genera. Moreover, we introduce the use of artificial bio-constructs to study U reduction by microbial communities to gain insights into the complex interactions in a multi-species environment. To gain molecular process understanding regarding microbial U reduction Desulfosporosinus and Desulfitobacterium spp. were chosen as important representatives of sulfate- and iron-reducing bacteria in anaerobic environments. Furthermore, their U reduction capabilities were investigated using artificial bio-constructs with different other microbial species.
Time-dependent experiments of pure cultures in bicarbonate buffer (30 mM, 100 µM U(VI), 10 mM lactate) showed a decrease of U concentrations in the supernatant of Desulfitobacterium sp. G1-2, whereas no changes occurred for Desulfosporosinus hippei DSM 8344T. In contrast, in artificial Opalinus Clay pore water (100 µM U(VI), pH 5.5, 10 mM lactate) up to 80% of the radionuclide got removed by both microorganisms. UV/Vis studies verified the reduction of U(VI) to U(IV) in the cell pellets. STEM-EDXX revealed the presence of two different U-containing aggregates inside the cells of Desulfitobacterium sp. G1-2, while cells of Desulfosporosinus hippei DSM 8344T showed almost no U uptake but U-aggregates on the cell surface.
First experiments with artificial bio-constructs that were formed from different bacterial genera using polyelectrolyte-controlled aggregation showed a promising U reduction capacity. Such artificial biostructures, in the form of aggregates or artificial biofilms, have a potential in investigating the complex interactions in multi-species environments and to utilize beneficial microbes in remediation strategies, even if they do not form biofilms themselves.

Keywords: Uranium(VI) reduction; bio-aggregates; anaerobic bacteria

  • Lecture (Conference) (Online presentation)
    ACS Spring 2023, 26.-30.03.2023, Indianapolis, USA

Permalink: https://www.hzdr.de/publications/Publ-36642


Complexation of neptunium(V) with aqueous phosphate using a dual experimental and quantum chemical approach

Miladi, E.; Réal, F.; Vallet, V.; Jordan, N.; Huittinen, N. M.

Abstract

Understanding and quantifying the chemistry of actinides with strong complexing ligands found in the environment is of key importance for predicting their mobility in the subsurface, especially with respect to the safety of high-level nuclear waste disposal. Phosphate ligands are present in the environment as they originate from the natural decomposition or microbially mediated solubilization processes of phosphate containing rocks and minerals. They can also be produced by anthropogenic activities such as fertilizers spread on the fields or phosphate-based detergents. Furthermore, phosphates are constituents of glasses and ceramics that may be used to immobilize high-level wastes.

Current thermodynamic databases contain very little data on actinide-phosphate complexes [1]. For the trivalent actinide curium, a recent study combining luminescence spectroscopy, thermodynamics, and quantum chemical (QC) calculations could unambiguously establish the formation of 1:1 and 1:2 phosphate complexes with the H₂PO₄⁻ ligand [2]. Complexation constants for both species were derived and extrapolated to standard conditions using the specific ion interaction theory. By combining the data obtained in the luminescence spectroscopic investigations, such as the crystal-field splitting of the emitting excited states and the luminescence lifetimes, with quantum chemical calculations, the coordination number of the complexes could be determined. At room temperature, both the 1:1 and 1:2 complexes are coordinated by 9 ligands. At elevated temperature, only the 1:1 complex retains a coordination number of 9, while one water molecule is released from the 1:2 complex, thereby reducing its coordination number to 8.

In this study, a similar combined experimental and computational approach will be applied to bridge the gaps in the databases for neptunium(V)-phosphate complexes. The complexation reaction will be studied with UV-vis and infrared (IR) spectroscopies at varying ionic strengths and temperatures under acidic pH conditions. Thereby, complexation constants and thermodynamic parameters for Np(V) aqua ion with phosphate can be derived for the formed Np(V)-H₂PO₄⁻ complex(es) (Figure 1). However, the experimental data alone, do neither hold information on the coordination of phosphate to the NpO₂⁺ cation (mono or bidentate binding), nor on the overall coordination number. This calls for relativistic QC calculations that will help characterizing the stoichiometry and geometries of the complexes. Indeed, QC methods can quantify the relative stability of these structures as well as the complexation strengths with aqueous phosphate through potential change of the coordination number with increasing temperature. The calculated vibrational frequency supports the assignment of bands within the measured IR spectra. In addition, the electronic structures at fundamental and excited states will be computed in order to predict the absorption bands of Np(V) – phosphate complexes in acidic solution. Ultimately, by using the quantum theory of atoms in molecules (QTAIM), the topology of the neptunyl-ligand bonds can be scrutinized to i) discuss the evolution of its character as additional phosphate ligands bind neptunyl and ii) to complement the evolution of the complexation constants determined experimentally.

[1] Grenthe, I. Gaona, X. Plyasunov, A. Rao, L. Runde, W.H. Grambow, B. Konings, R.J.M. Smith, A.L. Moore, E.E. (2020). Second Update on the Chemical Thermodynamics of Uranium, Neptunium, Plutonium, Americium and Technetium. Chemical Thermodynamics Volume 14, OECD Publications, Paris.
[2] Huittinen, N., Jessat, I., Réal, F., Vallet, V., Starke, S., Eibl, M., and Jordan, N. (2021). Revisiting the complexation of Cm(III) with aqueous phosphates: new insights from luminescence spectroscopy and ab initio simulations. Inorg. Chem. 60:10656−10673.

  • Poster
    Migration 2023, 24.-29.09.2023, Nantes, France

Permalink: https://www.hzdr.de/publications/Publ-36641


Annual Report 2022 - Institute of Ion Beam Physics and Materials Research

Faßbender, J.; Helm, M.; Zahn, P.; Zahn, M.

Abstract

Preface
Selected publications
Statistics (Publications and patents, Concluded scientific degrees; Appointments and honors; Invited conference contributions, colloquia, lectures and talks; Conferences, workshops, colloquia and seminars; Exchange of researchers; Projects)
Doctoral training programme
Experimental equipment
User facilities and services
Organization chart and personnel

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  • Open Access Logo Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-123 2023
    ISSN: 2191-8708, eISSN: 2191-8716

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Accurate temperature diagnostics for matter under extreme conditions

Dornheim, T.

Abstract

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 [1,2] 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. 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.

[1] T. Dornheim, M. Böhme, D. Kraus, T. Döppner, Th. Preston, Zh. Moldabekov, and J. Vorberger, Accurate temperature diagnostics for matter under extreme conditions, Nature Comm. 13, 7911 (2022)
[2] T. Dornheim, M. Böhme, D. Chapman, D. Kraus, T. Döppner, Th. Preston, Zh. Moldabekov, and J. Vorberger, Temperature analysis of X-ray Thomson scattering data, arXiv:2212.10510

  • Poster
    NIF and JLF User Group Meeting 2023, 21.02.2023, Livermore, California, USA

Permalink: https://www.hzdr.de/publications/Publ-36639


Distinct Effects of Chemical Toxicity and Radioactivity on Metabolic Heat of Cultured Cells Revealed by “Isotope-Editing”

Oertel, J.; Sachs, S.; Flemming, K.; Hassan Obeid, M.; Fahmy, K.

Abstract

Studying the toxicity of chemical compounds using isothermal microcalorimetry (IMC), which monitors the metabolic heat from living microorganisms, is a rapidly expanding field. The unprecedented sensitivity of IMC is particularly attractive for studies at low levels of stressors, where lethality-based data are inadequate. We have revealed via IMC the effect of low dose rates from radioactive β−-decay on bacterial metabolism. The low dose rate regime (<400 µGyh−1) is typical of radioactively contaminated environmental sites, where chemical toxicity and radioactivity-mediated effects coexist without a predominance or specific characteristic of either of them. We found that IMC allows distinguishing the two sources of metabolic interference on the basis of “isotope-editing” and advanced thermogram analyses. The stable and radioactive europium isotopes 153Eu and 152Eu, respectively, were employed in monitoring Lactococcus lactis cultures via IMC. β−-emission (electrons) was found to increase initial culture growth by increased nutrient uptake efficiency, which compensates for a reduced maximal cell division rate. Direct adsorption of the radionuclide to the biomass, revealed by mass spectrometry, is critical for both the initial stress response and the “dilution” of radioactivity-mediated damage at later culture stages, which are dominated by the chemical toxicity of Eu.

Keywords: bacteria; growth rate; isothermal microcalorimetry; low dose; metabolic monitoring

Permalink: https://www.hzdr.de/publications/Publ-36638


Surrogate Modelling for Boosting Research of Electron Acceleration Processes

Willmann, A.; Bethke, F.; Chang, Y.-Y.; Pausch, R.; Ghaith, A.; Debus, A.; Irman, A.; Schramm, U.; Hoffmann, N.

Abstract

Recent studies of laser plasma acceleration processes feature increasing requirements to the
technical equipment and time consumption in both numerical and experimental research.
This rising demand on statistical and mathematical methods for inversion of the system
state, comprehension of measurement data and quantification of data stability can only be
met by a comprehensive machine learning based surrogate model for Laser-driven Plasma
Accelerators (LPA). This surrogate potentially accelerates theoretical comprehension of the
system, novel means for design space exploration and promises reliable in-situ analysis of
experimental data which leads to novel guidance mechanisms for future LPA experiments.
The main aim of our work is to elaborate a surrogate model for electron acceleration
processes by virtue of that one could unveil beam dynamics on the scope of collected
diagnostic. Recently achieved results on laser-wakefield electron acceleration, demonstrate
the capability to learn an approximation of the data-dependent posterior distribution by
conditional inventible neural networks. The further derived model is able to describe an
electron bunch transformation in the simulated beam transport in terms of phase space
particle distribution based on its initial parameters: divergence and size. This step opens a
perspective to a potential elaborated model that could use obtained diagnostics for
reconstructions at any point in the electron beamline consisting of conventional magnetic
elements.

  • Poster
    767. WE-Heraeus-Seminar, 16.-18.05.2022, Physikzentrum Bad Honnef, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36637


Towards a Data-driven Digital Twin of a Free Electron Laser

Willmann, A.

Abstract

Sources of soft X-rays are highly appealing in research as they allow to image atomic- and
molecule- scaled structures, however high requirements to technical equipment complicate
application of such systems. Free electron laser is one of famous sources of ultra-intense
coherent X-ray beams. Convenient kilometer-scale electron accelerators make these
facilities expensive and difficult to maintain, while laser-driven electron accelerators might
significantly reduce size of free-electron lasers. In order to control such a source of X-rays
there are required time consuming numerical and experimental research. A rising demand
on statistical and mathematical methods for inversion of the system state, comprehension of
measurement data and quantification of data stability can only be met by a comprehensive
machine learning based digital twin for Free Electron Laser. The digital twin potentially
accelerates theoretical comprehension of the system, novel means for design space
exploration and promises reliable in-situ analysis of experimental diagnostics and
parameters which leads to democratization of laser-driven FELs accelerating fundamental
science in research field MATTER by collaborative efforts in Matter and Technologies. Digital
twin is comprising of multiple surrogate models for electron acceleration processes by virtue
of that one could unveil beam dynamics on the scope of collected diagnostic. This
formulation allows us to derive observables within the beamline promising physics-informed
inversion of the beamline meaning that we are able to explain observations guided by our
theoretical understanding.

  • Open Access Logo Lecture (Conference)
    8th MT meeting, 26.-27.09.2022, Hamburg, DESY, Deutschland
  • Open Access Logo Poster
    Helmholtz AI Evaluation, 06.-07.10.2022, München, Deutschland
  • Open Access Logo Poster
    IDESSAI Inria-DFKI European Summer School on AI 2022, 28.08.-02.09.2022, Universität des Saarlandes, Deutschland
  • Open Access Logo Poster
    Plasma Acceleration Bad Honnef Physics School, 05.-10.02.2023, Physikzentrum Bad Honnef, Deutschland
  • Open Access Logo Lecture (Conference)
    Helmholtz AI Conference 2023, 12.-14.06.2023, Hamburg, Germany

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Annual Report 2022 - Institute of Resource Ecology

Stumpf, T.; Foerstendorf, H.; Bok, F.; Richter, A.

Abstract

The Institute of Resource Ecology (IRE) is one of the ten institutes of the Helmholtz-Zentrum Dresden – Rossendorf (HZDR). Our research activities are mainly integrated into the program “Nuclear Waste Management, Safety and Ra-diation Research (NUSAFE)” of the Helmholtz Association (HGF) and focus on the topics “Safety of Nuclear Waste Disposal” and “Safety Research for Nuclear Reactors”. The program NUSAFE, and therefore all work which is done at IRE, belong to the research field “Energy” of the HGF.

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  • Open Access Logo Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-122 2023
    ISSN: 2191-8708, eISSN: 2191-8716

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Abendschule: Radioaktivität

Woschni, U.; Foerstendorf, H.

Abstract

Radio broadcast, coloRadio

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    Radio broadcast 06.09.2022

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GPU-accelerated coupled ptychographic tomography

Achilles, S.; Ehrig, S.; Hoffmann, N.; Kahnt, M.; Becher, J.; Fam, Y.; Sheppard, T.; Brückner, D.; Schropp, A.; Schroer, C. G.

Abstract

Scanning coherent X-ray microscopy (ptychography) has gained considerable interest during the last decade since the performance of this indirect imaging technique does not necessarily rely on the quality of the X-ray optics and, in principle, can achieve highest spatial resolution in X-ray imaging. The method can be easily extended to 3D by adding standard tomographic reconstruction schemes. However, the tomographic reconstruction is often applied in a subsequent step using a sequence of aligned ptychographic 2D projections. In this contribution, we outline current developments of a GPU-accelerated framework for direct 3D ptychography, coupling 2D ptychography and tomography. The program utilizes a custom GPU-accelerated framework for ptychography that offers three distinct ptychographic reconstruction algorithms. The tomographic reconstruction runs simultaneously and uses numerical routines of the ASTRA Toolbox. This parallel-computing approach results in a high performance increase considerably reducing the reconstruction time of 3D ptychographic datasets.

  • Contribution to proceedings
    SPIE Optical Engineering + Applications, 14.10.2022, San Diego, USA
    Proc. SPIE 12242, Developments in X-Ray Tomography XIV, 122420N
    DOI: 10.1117/12.2633102
    Cited 2 times in Scopus

Permalink: https://www.hzdr.de/publications/Publ-36632


Amortized Bayesian Inference of GISAXS Data with Normalizing Flows

Zhdanov, M.; Randolph, L.; Kluge, T.; Nakatsutsumi, M.; Gutt, C.; Ganeva, M.; Hoffmann, N.

Abstract

Grazing-Incidence Small-Angle X-ray Scattering (GISAXS) is a modern imaging technique used in material research to study nanoscale materials. Reconstruction of the parameters of an imaged object imposes an ill-posed inverse problem that is further complicated when only an in-plane GISAXS signal is available. Traditionally used inference algorithms such as Approximate Bayesian Computation (ABC) rely on computationally expensive scattering simulation software, rendering analysis highly time-consuming. We propose a simulation-based framework that combines variational auto-encoders and normalizing flows to estimate the posterior distribution of object parameters given its GISAXS data. We apply the inference pipeline to experimental data and demonstrate that our method reduces the inference cost by orders of magnitude while producing consistent results with ABC.

Keywords: GISAXS; Simulation-based inference

  • Open Access Logo Contribution to proceedings
    Machine Learning and the Physical Sciences @ Neural Information Processing Systems, 3.12.2022, New Orleans, USA

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Permalink: https://www.hzdr.de/publications/Publ-36631


Exploring the complexation of curium(III) and europium(III) with aqueous phosphates: a combined experimental and ab initio study

Réal, F.; Huittinen, N. M.; Jessat, I.; Vallet, V.; Jordan, N.

Abstract

The environmental fate of radionuclides (RNs) such as actinides and fission products disposed in underground nuclear waste repositories is of major concern. Long-term safety assessments of these disposal sites rely on the ability of geochemical models and thermodynamic databases (TDB) to forecast the mobility of RNs over very long time periods. One example where large data gaps in TDB still exist is related to the complexation of trivalent actinides and lanthanides with aqueous phosphates. Indeed, solid phosphate monazites are one of the candidates for the immobilization of specific high-level waste streams for safe storage in deep underground repositories in the future, which could locally increase the occurrence of phosphate in the repository.
Recent works [1-3] have been carried out to partially close these gaps in order to provide reliable complexation constants at 298K and at elevated temperature. However, obtaining this information is challenging and requires the identification of the formed complexes by means of spectroscopic techniques, such as UV-Vis or TRLFS (Time-Resolved Laser Fluorescence Spectroscopy). Depending on the phosphate concentration, mono or bi-dendate phosphate complexes can be formed with various coordination numbers (8, 9). However, it is often a challenge to obtain further information about the complex structures from the spectroscopic data alone.
In this context, relativistic quantum chemical (QC) methods can be seen as an additional tool to complement the experimental observations. In this study, structural properties, electronic structures and thermodynamics of the 1:1 and 1:2 phosphate complexes of Cm(III) and Eu(III) (see below) have been extracted by state-of-the-art QC calculations. In particular, QC methods allowed i) studying the complexation strengths of Cm(III) and Eu(III) with aqueous phosphates, ii) suggesting a potential change of the coordination number with increasing temperature and iii) probing the character (ionic/covalent) of the Cm/Eu-water and Cm/Eu-phosphate bonds.

Combining the information obtained from the quantum chemical calculations with the observed spectral changes, facilitates a conclusive assignment of the phosphate complex structures and their overall coordination [2,3].

[1] Jordan, N., Demnitz, M., Lösch, H., Starke, S., Brendler, V., and Huittinen, N. (2018). Complexation of trivalent lanthanides (Eu) and actinides (Cm) with aqueous phosphates at elevated temperatures. Inorg. Chem. 57:7015−7024.
[2] Huittinen, N., Jessat, I., Réal, F., Vallet, V., Starke, S., Eibl, M., and Jordan, N. (2021). Revisiting the complexation of Cm(III) with aqueous phosphates: new insights from luminescence spectroscopy and ab initio simulations. Inorg. Chem. 60:10656−10673.
[3] Jessat, I., Jordan, N., Kretzschmar, J., Réal, F., Vallet, V., Stumpf, T., and Huittinen, N. (2023). Impact of temperature on the complexation of Eu(III) with phosphate ions: a spectroscopic and ab initio study. Inorg. Chem. (in preparation).

  • Poster
    Migration 2023, 24.-29.09.2023, Nantes, France

Permalink: https://www.hzdr.de/publications/Publ-36630


Meta-analysis of expression and targeting of cell adhesion associated genes in nine cancer types – a one research lab re-evaluation

Borodins, O.; Broghammer, F.; Seifert, M.; Cordes, N.

Abstract

Cancer presents as a highly heterogeneous disease with partly overlapping and partly distinct
(epi)genetic characteristics. These characteristics determine inherent and acquired resistance,
which need to be overcome for improving patient survival. In line with the global efforts in
identifying druggable resistance factors, extensive preclinical research of the Cordes lab and others
designated the cancer adhesome as a critical and general therapy resistance mechanism with
multiple druggable cancer targets. In our study, we addressed pancancer cell adhesion mechanisms
by connecting the preclinical datasets generated in the Cordes lab with publicly available
transcriptomic and patient survival data. We identified similarly changed differentially expressed
genes (scDEGs) in nine cancers and their corresponding cell models relative to normal tissues.
Those scDEGs interconnected with 212 molecular targets from Cordes lab datasets generated
during two decades of research on adhesome and radiobiology. Intriguingly, integrative analysis
of adhesion associated scDEGs, TCGA patient survival and protein-protein network
reconstruction revealed a set of overexpressed genes adversely affecting overall cancer patient
survival and specifically the survival in radiotherapy-treated cohorts. This pancancer gene set
includes key integrins (e.g. ITGA6, ITGB1, ITGB4) and their interconnectors (e.g. SPP1, TGFBI),
affirming their critical role in the cancer adhesion resistome. In summary, this meta-analysis
demonstrates the importance of the adhesome in general, and integrins together with their
interconnectors in particular, as potentially conserved determinants and therapeutic targets in
cancer.

Keywords: Integrins; Adhesion; gene expression; network analysis; pancancer

Permalink: https://www.hzdr.de/publications/Publ-36629


Learning Generative Factors of EEG Data with Variational auto-encoders

Zhdanov, M.; Steinmann, S.; Hoffmann, N.

Abstract

Electroencephalography produces high-dimensional, stochastic data from which it might be challenging to extract high-level knowledge about the phenomena of interest. We address this challenge by applying the framework of variational auto-encoders to 1) classify multiple pathologies and 2) recover the neurological mechanisms of those pathologies in a data-driven manner. Our framework learns generative factors of data related to pathologies. We provide an algorithm to decode those factors further and discover how different pathologies affect observed data. We illustrate the applicability of the proposed approach to identifying schizophrenia, either followed or not by auditory verbal hallucinations. We further demonstrate the ability of the framework to learn disease-related mechanisms consistent with current domain knowledge. We also compare the proposed framework with several benchmark approaches and indicate its classification performance and interpretability advantages.

Keywords: Variational auto-encoders; Causal representation learning; EEG

  • Open Access Logo Contribution to proceedings
    DGM4MICCAI, 22.09.2022, Singapore, Singapore

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Permalink: https://www.hzdr.de/publications/Publ-36628


Comparison of 3D and 4D robustly optimized proton treatment plans for non-small cell lung cancer patients with tumour motion amplitudes larger than 5 mm

Spautz, S.; Haase, L.; Tschiche, M.; Makocki, S.; Richter, C.; Troost, E. G. C.; Stützer, K.

Abstract

Background and purpose: There is no consensus about an ideal robust optimization (RO) strategy for proton therapy of targets with large intra-fractional motion. We investigated the plan robustness of different RO strategies regarding setup/range errors, interplay effects and interfractional anatomical changes.
Materials and methods: For eight non-small cell lung cancer patients with primary and/or nodal clinical target volume (CTVp/CTVn) with motion >5mm, different RO approaches were investigated: 3DRO considering the average CT (AvgCT) with a target density override, 4DRO considering three/all 4DCT phases, and 4DRO considering the AvgCT and three/all 4DCT phases. Realistic interplay scenarios were reconstructed based on patient breathing and machine logfile data for deliveries with/without layered rescanning. Robustness against setup/range errors, interplay effects and interfractional anatomical changes were analyzed for target coverage and OAR sparing.
Results: All nominal plans fulfilled the clinical requirements, while 4DRO without AvgCT generated the most conformal dose distributions. Robustness against setup/range errors was best for 4DRO with AvgCT. No RO strategy was sufficient in countervailing fraction-wise dose distortions caused by interplay effects. Irrespective of rescanning, target coverage was restored in all cases when accumulating four interplay scenarios. 4DRO with AvgCT showed higher CTVp robustness against interfractional changes, but plan adaptations are necessary for all RO strategies in case of relevant anatomical changes.
Conclusion: All RO strategies are clinically acceptable but exhibit equally low robustness against interplay effects. To ensure fraction-wise target coverage, additional motion mitigation is required for CTVs with large motion amplitudes and interfractional changes need to be monitored.

Keywords: Proton therapy; Treatment plannung; Non-small cell lung cancer; Robustness; Interplay effect

Permalink: https://www.hzdr.de/publications/Publ-36627


Three-dimensional dynamics of a single bubble rising near a vertical wall: paths and wakes

Yan, H.-J.; Zhang, H.-Y.; Zhang, H.-M.; Liao, Y.; Liu, L.

Abstract

In order to clarify the migration mechanism and wake behavior of a single bubble rising near a vertical wall, three-dimensional direct numerical simulations are implemented based on the open-source software Basilisk and various types of migration paths like linear, zigzag and spiral are investigated. The volume of fluid (VOF) method is used to capture the bubble interface at a small scale, while the gas-liquid interface and high-velocity-gradient regions in the flow field are encrypted with the adaptive mesh refinement technology. The results show that the vertical wall has an obstructive effect on the diffusion of the vortex boundary layer on the surface of the bubble migrating in a straight line, and the resulting reaction force tends to push the bubbles away from the wall surface. For the zigzag or spiral movement of a bubble in the x-y plane, the perpendicular wall is an unstable factor, but on the contrary, the motion in
the z-y plane is stabilized.

Keywords: Bubble; Wall effect; Trajectory; Wake structure; VOF; Basilisk

Permalink: https://www.hzdr.de/publications/Publ-36626


Adversarial Attacks On Aerial Vehicle Policies; Poster 2022

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

Abstract

Deep Neural Networks are widely applied for solving Computer Vision tasks for Unmanned Aerial Vehicles (UAVs). For some applications, the predictions of the neural networks (NNs) directly influence the motion planning or control of the UAVs. However, the neural networks are highly prone to adversarial attacks, which has a severe negative impact on the drone’s safe operation. With this work, we are planning to perform a physically realizable attack on a neural network analyzing camera images. The control of the UAV is directly influenced by the predictions of this NN. The generated adversarial attacks will be printed and attached as adversarial patches to an attacker UAV. By choosing which patch to present given the current relative poses of victim and attacker, the attacker will achieve full control over the victim UAV.

  • Open Access Logo Poster
    Big data analytical methods for complex systems, 06.-07.10.2022, Wrocław, Polska

Downloads

Permalink: https://www.hzdr.de/publications/Publ-36625


The p-center problem under locational uncertainty of demand points

Ataei, H.; Davoodi Monfared, M.

Abstract

The p-center problem is finding the location of p facilities among a set of n demand points such that the maximum distance between any demand point and its nearest facility is minimized. In this paper, we study this problem in the context of uncertainty, that is, the location of the demand points may change in a region like a disk or a segment, or belong to a finite set of points. We introduce Max-p-center and Min-p-center problems which are the worst and the best possible solutions for the p-center problem under such locational uncertainty. We propose approximation and parameterized algorithms to solve these problems under the Euclidean metric. Further, we study the MinMax Regret 1-center problem under uncertainty and propose a linear-time algorithm to solve it under the Manhattan metric as well as an O(n4) time algorithm under the Euclidean metric.

Keywords: Facility location; p-center; Uncertainty; Regret; Robustness; Approximation algorithms

Downloads

Permalink: https://www.hzdr.de/publications/Publ-36624


LiFe-net: Data-driven Modelling of Time-dependent Temperatures and Charging Statistics Of Tesla’s LiFePo4 EV Battery

Rustamov, J.; Fennert, L.; Hoffmann, N.

Abstract

Modelling the temperature of Electric Vehicle (EV) batteries is a fundamental task of EV manufacturing. Extreme temperatures in the battery packs can affect their longevity and power output. Although theoretical models exist for describing heat transfer in battery packs, they are computationally expensive to simulate. Furthermore, it is difficult to acquire data measurements from within the battery cell. In this work, we propose a data-driven surrogate model (LiFe-net) that uses readily accessible driving diagnostics for battery temperature estimation to overcome these limitations. This model incorporates Neural Operators with a traditional numerical integration scheme to estimate the temperature evolution. Moreover, we propose two further variations of the baseline model: LiFe-net trained with a regulariser and LiFe-net trained with time stability loss. We compared these models in terms of generalization error on test data. The results showed that LiFe-net trained with time stability loss outperforms the other two models and can estimate the temperature evolution on unseen data with a relative error of 2.77 % on average.

  • Open Access Logo Contribution to proceedings
    DLDE Workshop in the 36th Conference on Neural Information Processing Systems (NeurIPS 2022)., 21.10.2022, Virtual Workshop, Virtual Workshop

Downloads

Permalink: https://www.hzdr.de/publications/Publ-36623


Deep Spiking Quantum Neural Network for Noisy Image Classification

Konar, D.; Sarma, A. D.; Bhandary, S.; Cangi, A.

Abstract

stochastic-based modelling, promising that the inherent uncertainty in quantum computing will prove to be a significant advantage, driving quantum and neuromorphic computing research
to new heights. Spiking Neural Networks (SNNs) are gaining popularity due to their inherent ability to process spatial and temporal data. However, it is a daunting task to train
the network weights of classical SNN due to the stochastic behaviour of neuron signals and the inherent non-differentiable spike events. This paper introduces a supervised Deep Spiking
Quantum Neural Network (DSQ-Net) using a hybrid classicalquantum framework having the merits of amplitude encoding in a dressed quantum layer. A novel attempt has been made
to obviate the challenges in training a classical SNN, assisted by a Variational Quantum Circuit (VQC) in the proposed hybrid classical-quantum framework. The proposed DSQ-Net
is rigorously validated and benchmarked on the ideal PennyLane Quantum Simulator with limited quantum hardware. The experiments have been conducted on unseen test images with imposed noise from the FashionMNIST, MNIST, KMNIST and CIFAR-10 datasets. Classification accuracy is reported to be 95.6% for the proposed DSQ-Net model and
it outperforms the classical counterpart (Deep Spiking Neural Networks), shallow Random Quantum Neural Networks (RQNN), ResNet-18 and AlexNet. The PyTorch implementation
of DSQ-Net is made available on Github0:https://anonymous.4open.science/r/DSQ-Net-037E.

Keywords: Quantum computing; Spiking neural networks; IBM quantum computer; qubit

  • Poster
    26th Quantum Information Processing Conference (QIP), 04.-10.02.2023, Ghent, Belgium

Permalink: https://www.hzdr.de/publications/Publ-36622


Reconstruction of SAXS Data using cINNs

Thiessenhusen, E.; Rödel, M.; Kluge, T.; Bussmann, M.; Cowan, T.; Hoffmann, N.

Abstract

The understanding of laser-solid interactions is important to the development of future laser-driven particle and photon sources, e.g., for tumor therapy, astrophysics or fusion. Currently, these interactions can only be modeled by simulations which need verification in the real world. Consequently, in 2016, a
pump-probe experiment was conducted by Thomas Kluge to examine the laser-plasma interaction that occurs when an ultrahigh-intensity laser hits a solid density target. To handle the nanometer spatial and femtosecond temporal resolution of the laser-plasma interactions, Small-Angle X-Ray Scattering (SAXS) was used as a diagnostic to reconstruct the laser-driven target. However, the reconstruction of the target from the SAXS diffraction pattern is an inverse problem which are often ambiguous, due to the phase problem, and has no closed-form solution. We aim to simplify the process of reconstructing the target from SAXS images by employing Neural Networks, due to their speed and generalization capabilities. To be more specific, we use a conditional Invertible Neural Network (cINN), a type ofNormalizing Flows, to resolve the ambiguities of the target with a probability density distribution. The
target in this case is modelled by a simple grating function with three parameters. We chose this analytically well-defined and relatively simple target as a trial run for Neural Networks in this field to pave the way for more sophisticated targets and methods. Unfortunately, we don’t have enough and reliable experimental data that could be used as training. So, in consequence, the network is trained only on simulated diffraction patterns and their respective ground truth parameters. The cINN is able to accurately reconstruct simulated- as well as preshot data. The performance on main-shot data remains unclear due to the fact that the simulation might not be able to explain the governing processes.

  • Lecture (Conference)
    Helmholtz AI Conference, 02.-03.06.2022, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36621


Reconstruction of Small-Angle X-ray Scattering data using Invertible Neural Networks

Thiessenhusen, E.; Rödel, M.; Kluge, T.; Bussmann, M.; Cowan, T.; Hoffmann, N.

Abstract

The understanding of laser-solid interactions is important to the development of future laser-driven particle and photon sources, e.g., for tumor therapy, astrophysics or fusion. Currently, these interactions can only be modeled by simulations which need verification in the real world. Consequently, in 2016, a pump-probe experiment was conducted by Thomas Kluge to examine the laser-plasma interaction that occurs when an ultrahigh-intensity laser hits a solid density target. To handle the nanometer spatial and femtosecond temporal resolution of the laser-plasma interactions, Small-Angle X-Ray Scattering
(SAXS) was used as a diagnostic to reconstruct the laser-driven target. However, the reconstruction of the target from the SAXS diffraction pattern is an inverse problem which are often ambiguous, due to the phase problem, and has no closed-form solution. We aim to simplify the process of reconstructing the target from SAXS images by employing Neural Networks, due to their speed and generalization capabilities. To be more specific, we use a conditional Invertible Neural Network (cINN), a type of Normalizing Flows, to resolve the ambiguities of the target with a probability density distribution. The target in this case is modelled by a simple grating function with three parameters. We chose this analytically well-defined and relatively simple target as a trial run for Neural Networks in this field to pave the way for more sophisticated targets and methods. Unfortunately, we don’t have enough and reliable experimental data that could be used as training. So, in consequence, the network is trained only on simulated diffraction patterns and their respective ground truth parameters. The cINN is able to accurately reconstruct simulated- as well as preshot data. The performance on main-shot data remains unclear due to the fact that the simulation might not be able to explain the governing processes.

  • Lecture (Conference) (Online presentation)
    SEI Workshop, 21.-23.03.2022, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36620


Reconstruction of SAXS data using Invertible Neural Networks

Thiessenhusen, E.; Rödel, M.; Kluge, T.; Bussmann, M.; Cowan, T.; Hoffmann, N.

Abstract

The understanding of laser-solid interactions is important to the development of future laser-driven particle and photon sources, e.g., for tumor therapy, astrophysics or fusion. Currently, these interactions can only be modeled by simulations which need verification in the real world. Consequently, in 2016, a pump-probe experiment was conducted by Thomas Kluge to examine the laser-plasma interaction that occurs when an ultrahigh-intensity laser hits a solid density target. To handle the nanometer spatial and femtosecond temporal resolution of the laser-plasma interactions, Small-Angle X-Ray Scattering (SAXS) was used as a diagnostic to reconstruct the laser-driven target. However, the reconstruction of the target from the SAXS diffraction pattern is an inverse problem which are often ambiguous and has no closed-form solution. We aim to simplify the process of reconstructing the target from SAXS images by employing Neural Networks due to their speed and generalization capabilities. To be more specific, we use a conditional Invertible Neural Network (cINN) to resolve the ambiguities with a probability density distribution. In consequence, the cINN is trained on simulated diffraction patterns and their respective
ground truth parameters. The cINN is able to accurately reconstruct simulated- as well as preshot data.
The performance on main-shot data remains unclear due to the fact that the simulation might not be able
to explain the governing processes.

  • Lecture (Conference)
    SNI 2022, 05.-07.09.2022, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36619


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

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

Abstract

The structure and properties of iron hydrides under pressure have been of interest to geoscientists. At ambient conditions, there are no stable solid iron hydrides. Previous theoretical and experimental studies suggest that the double hcp phase of FeH is stable at low pressures with phase transitions to the hcp and fcc phases up to 80 and 140 GPa, respectively. Here, we present a theoretical investigation of the potential energy surfaces of FeH at high pressure. We construct a highly transferable machine-learned interatomic potential with a hierarchical approach using the PyFLAME code. Then, using this fast and accurate neural network potential, we systematically explore the potential energy surfaces of bulk structures of FeH by global sampling using the minima hopping method, to predict stable and metastable iron hydrides up to 200 GPa. We have carried out density functional theory calculations to refine the predicted structures and to evaluate the dynamical stability of selected structures as well. In an automated and systematic approach, we are going to show how a transferable machine-learned interatomic potential can be trained and validated using global optimization and analyze the phase diagram of the stoichiometric Fe-H system under pressure.

  • Poster
    DPG spring meetings, 27.03.2023, TU Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-36618


Efficient calculations of equation-of-state data in the warm-dense matter regime

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

Abstract

Equation-of-state (EoS) data — relating the pressure and internal energy to material density and temperature — is a key quantity in the warm dense matter regime, for example as input to hydrodynamics codes used to guide inertial confinement fusion experiments. The first-principles methods, density-functional theory and path-integral Monte–Carlo, are considered state-of-the-art approaches to calculate EoS data. However, both methods are computationally expensive, which motivates the development of low-cost approaches such as average-atom models. In the first part of this talk, we benchmark EoS results from an average-atom model against the extensive first-principles dataset from Militzer et al. (Phys. Rev. E 103, 013203). In the second part, we develop a neural-network surrogate model as a numerically feasible alternative to calculating EoS data. We train two neural networks to interpolate this dataset, with one being trained using average-atom outputs and the other without. We also compare the accuracy of the machine-learned and average-atom models using out-of-distribution data from other sources.

  • Lecture (Conference)
    APS March Meeting 2023, 05.-10.03.2023, Las Vegas, USA

Permalink: https://www.hzdr.de/publications/Publ-36617


Data publication: Modelling of non-uniform core deformations in SFRs by using DYN3D with coordinate transformation method in the framework of the ESFR-SMART project Task1.4.3

Nikitin, E.

Abstract

The research data contains reactor core models, homogenized cross section data, calculation results and post-processing scripts for the verification and validation of the coordinate transformation method for non-uniform radial expansions of SFR cores.

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

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-36616


Static modeling of core flowering scenarios in SFRs with nodal diffusion code DYN3D

Nikitin, E.; Fridman, E.

Abstract

In recent years, the reactor core simulator DYN3D has become a frequently used tool for neutronic analyses of Sodium cooled Fast Reactors (SFRs) by the Reactor Safety Group of the Helmholtz-Zentrum Dresden-Rossendorf. The capabilities of the code are constantly expanding with new models, such as the various thermal expansion models relevant for SFR neutronic behavior. This study presents the extension of the radial expansion module for the modeling of non-uniform core expansions, i.e. core flowerings. Since DYN3D uses regular numerical meshes for its neutronic solvers, the implementation of the coordinate transformation method (CTM) was performed to cope with non-uniform core deformations. First, the implementation of the CTM was tested on a realistic SFR core for lifelike core flowering scenarios. The DYN3D results were compared against the Monte Carlo reference solutions. Second, DYN3D was validated against the core flowering experiment performed in the Phenix reactor. The measured reactivity effects of the static deformations were used to assess the DYN3D performance. At both stages, the obtained results show an acceptable agreement with the references, thus demonstrating the applicabilty of DYN3D for modeling various core flowering scenarios.

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

Related publications

  • Contribution to proceedings
    2023 International Congress on Advances in Nuclear Power Plants (ICAPP 2023), 23.-27.04.2023, Gyeongju, Korea
  • Lecture (Conference)
    2023 International Congress on Advances in Nuclear Power Plants (ICAPP 2023), 23.-27.04.2023, Gyeongju, Korea

Permalink: https://www.hzdr.de/publications/Publ-36615


Assessment of anthropogenic actinide background levels on the ground of the new 1-MV compact AMS system HAMSTER

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

Abstract

The new multi-purpose 1-MV AMS facility HAMSTER (Helmholtz
Accelerator Mass Spectrometer for Tracing Environmental Radionuclides)
is built within the HZDR research campus in Dresden-
Rossendorf starting in 2022. The new machine is especially dedicated
to the analysis of ultra-trace levels of actinides in environmental
samples. Therefore, eventual contamination of the site where the
new accelerator building is being constructed should be avoided and
clarified. Hence, several soil samples close to the construction site of
the new accelerator building have been analyzed to assess the content
and isotopic ratios of the actinides U, Np and Pu. The samples
have been processed in the existing chemistry labs of HZDR’s 6-MV
DREAMS facility showing low background levels. Overall, the samples
show expected signatures of global fallout in Pu concentrations
and APu/239Pu ratios. However, in some samples increased 236U
concentrations and relatively low 233U/236U atomic ratios have been
detected pointing to an additional source of 236U. Additional analysis
is currently ongoing.

  • Poster
    DPG-Frühjahrstagung, 09.03.2023, Hannover, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36614


Concepts in Strong-field QED

Hernandez Acosta, U.

Abstract

Usually, quantum electrodynamics is the prime example, when it comes to a well-understood and outstandingly precise description of elementary particle processes. However, modern laser facilities provide highly intense light with a non-trivial temporal structure, where an arbitrary number of ‘photons’ from the light source may interact with the colliding particles. In this case, the standard perturbative treatment, e.g. known from quantum electrodynamics, becomes very cumbersome and impractical. Accordingly, there are, among others, wide theoretical investigations w.r.t. scattering processes of particles impinging these extreme light sources. This has been done by applying strong-field quantum electrodynamics, which is a theory of electromagnetic interactions within coherent highly intense light treated as a classical background field. Here, the distinction between a classical background field and a quantised photon field revealed a vast amount of novel non-linear structures and non-perturbative phenomena. In this seminar, we introduce the basic concepts of strong-field QED and derive the Feynman rules for the theory. Then we apply those rules to the Breit-Wheeler process, i.e. the electron-positron pair production in the collision of a laser field and a highly energetic photon

  • Invited lecture (Conferences)
    IKTP - Institutsseminar, 12.01.2023, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-36613


Strong-field physics prospects at 50 keV at EuXFEL

Hernandez Acosta, U.; Steiniger, K.; Bussmann, M.; Cowan, T.

Abstract

Some studies of applying a 50 keV XFEL for strong-field physics, modelled by the interaction with an electron beam, were presented. The process of electron-positron pair production in strong fields deviates from the well-known perturbative result in weak field backgrounds. In a strong field background, an electron can directly emit a photon, generating a pair via the trident process. Using 50 keV photons, only about 5 MeV kinetic electron energy is required to reach the trident threshold, which is available by electron guns or laser acceleration (in solids, or wakefield). The trident process can also be used to test models for dark matter candidates. Using the proposed massive “dark photon”, the assumed mass and coupling to ordinary could be determined more precisely than with hadron experiments. Certain exclusion regions can be scanned, but the trident experiment could also be used to detect dark matter (instead of excluding certain mass/coupling ranges) because there is full control over the QED background. A second scheme is the interaction of hard x-rays with electrons in the presence of an intense, infrared few-cycle laser light field. It allows to study of laser-assisted Compton scattering, Breit Wheeler pair production and trident, where during the peaks of the few-cycle IR laser field, spectral features are introduced. A (quasi-) continuous X-ray beam (as in a synchrotron) is not sufficient for strong-field studies as high intensity is required. A user community, similar to established synchrotron or XFEL users, may not exist yet. Many colleagues work on theoretical models, but more experimentalists will emerge with upcoming experimental capabilities at XFELs. The LUXE experiment at DESY, and the detection of QED vacuum birefringence at HED/HIBEF, EuXFEL, are examples of such developments.

Involved research facilities

  • HIBEF
  • Invited lecture (Conferences)
    Scientific Opportunities with very Hard XFEL Radiation, 18.-20.01.2023, Desy, Hamburg, Germany

Permalink: https://www.hzdr.de/publications/Publ-36612


QED.jl - First-Principal Description of QED-Processes in x-ray laser fields

Hernandez Acosta, U.; Steiniger, K.; Jungnickel, T.; Bussmann, M.

Abstract

We present a novel approach for an event generator inherently using exact QED descriptions to predict the results of high-energy electron-photon scattering experiments that can be performed at modern X-ray free-electron laser facilities. Future experiments taking place at HIBEF, LCLS, and other facilities targeting this regime, will encounter processes in x-ray scattering from (laser-driven) relativistic plasmas, where the effects of the energy spectrum of the laser field as well as multi-photon interactions can not be neglected anymore. In contrast to the application window of existing QED-PIC codes, our event generator makes use of the fact, that the classical nonlinearity parameter barely approaches unity in high-frequency regimes, which allows taking the finite bandwidth of the x-ray laser into account in the description of the QED-like multi-photon interaction. Consequently, we exploit these effects in Compton scattering, Breit-Wheeler pair-production and trident pair-production in x-ray laser fields as one of the driving forces of electromagnetic cascades and plasma formation.

Keywords: Strong-field QED; Simulation; Monte-Carlo methods

  • Lecture (Conference)
    43rd International Workshop on High-Energy-Density Physics with Intense Ion and Laser Beams, 30.01.-03.02.2023, Hirschegg, Austria

Permalink: https://www.hzdr.de/publications/Publ-36611


Potential margin reduction in prostate cancer proton therapy when using prompt gamma imaging for online treatment verification

Bertschi, S.; Stützer, K.; Berthold, J.; Pietsch, J.; Smeets, J.; Janssens, G.; Richter, C.

Abstract

An estimation for the potential reduction of clinical margins when using prompt gamma imaging for online treatment verification in proton therapy of prostate cancer is provided. For two adaptive scenarios a potential reduction relative to the clinical practice was evaluated. Using the current trolley-mounted PGI system for online treatment verification to trigger an adaptation, the current range uncertainty margins used at our institute could be reduced by 57%. Additional volumetric imaging at isocenter before irradiation could also reduce the setup uncertainty margins by 66%. A case example illustrates the corresponding dose sparing.

Keywords: proton therapy; range verification; prompt gamma imaging; margin reduction; prostate cancer

Involved research facilities

  • OncoRay

Permalink: https://www.hzdr.de/publications/Publ-36610


Data publication: ESFR-SMART T1.2.4

Nikitin, E.

Abstract

Coupled Neutronic/Thermal-Hydraulic calculations of the European Sodium cooled Fast Reactor core with reactor simulator DYN3D in the framework of the H2020 ESFR-SMART project, Task 1.2.4.

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-36609


Impact of Thermal-Hydraulic Feedback and Differential Thermal Expansion on European SFR Core Power Distribution

Lindley, B.; Álvarez Velarde, F.; Baker, U.; Bodi, J.; Cosgrove, P.; Charles, A.; Fiorina, C.; Fridman, E.; Krepel, J.; Lavarenne, J.; Mikityuk, K.; Nikitin, E.; Ponomarev, A.; Radman, S.; Shwageraus, E.; Tollit, B.

Abstract

The objective of this paper is to quantify the coupling effect on the power distribution of sodium-cooled
fast reactors (SFRs), specifically the European SFR. Calculations are performed with several state-of-the-art
reactor physics and Multiphysics codes (TRACE/PARCS, DYN3D, WIMS, COUNTHER and GeN-Foam) to build
confidence in the methodologies and validity of results. Standalone neutronics calculations were generally
in excellent agreement with a reference Monte Carlo-calculated power distribution (from Serpent). Next,
the impact of coolant density and fuel temperature Doppler feedback was calculated. Reactivity
coefficients for perturbations in the inlet temperature, coolant heat up and core power were shown to be
negative with values of around -0.5 pcm/°C, -0.3 pcm/°C and -3.5 pcm/% respectively. Fuel temperature
and coolant density feedback was found to introduce a roughly -1%/+1% in/out power tilt across the core.
Calculations were then extended to axial expansion for cases where fuel is linked and unlinked to the clad.
Core calculations are in good agreement with each other. The impact of differential fuel expansion is found
to be larger for fuel both linked and unlinked to the clad, with the in/out power tilt increasing to around -
4%/+2%. Thus, while broadly confirming the known result that standalone physics calculations give good
results, the expansion coupling effect is perhaps more than anticipated a priori. These results provide a
useful benchmark for the further development of Multiphysics codes and methodologies in support of
advanced reactor calculations.

Related publications

Permalink: https://www.hzdr.de/publications/Publ-36608


Coupled Neutronic-Thermal-Hydraulic Simulations of the European SFR Core

Lindley, B.; Álvarez, V. F.; Bodi, J.; Charles, A.; Di Nora, V. A.; Fridman, E.; Krepel, J.; Lavarenne, J.; Mikityuk, K.; Nikitin, E.; Ponomarev, A.; Tollit, B.

Abstract

Within the European SFR – Safety Measures Assessment and Research Tools (ESFR-SMART) project, steady-state coupled simulation of the ESFR core has been performed using several core analysis packages, with the objective of quantifying the coupling effect. Focus is on the fuel Doppler effect and coolant expansion effect. Standalone neutronics calculations in TRACE/PARCS (PSI), DYN3D (HZDR) and WIMS (Jacobs) showed superb agreement with the reference Serpent power distribution (root mean square (rms) discrepancies of 1.3%, 1.5% and 0.7% respectively). Results for COUNTHER (CIEMAT) were also in reasonable agreement, but with a somewhat higher discrepancy of 3.7%. Temperature distributions from thermal-hydraulic calculations were also compared and are found to be in good agreement. The effect of Doppler and coolant density feedback on core power distribution was predicted by TRACE/PARCS, DYN3D and WIMS to be between 0.4% and 0.8% rms difference in assembly powers. Reactivity coefficients for perturbations in the inlet temperature, flow rate and core power were shown to be negative for these three codes, with values of roughly -0.5 pcm/°C, -0.3 pcm/°C and -3.5 pcm/% respectively. A preliminary investigation of differential thermal expansion effects indicates that this may have a significant effect on core power distribution of a few %, greater than anticipated a priori and may warrant inclusion in coupled core analysis to ensure the accurate calculation of power distributions.

Keywords: ESFR-SMART; coupled calculations; sodium-cooled fast reactors

Related publications

  • Contribution to proceedings
    PHYSOR 2022: Making Virtual a Reality - Advancements in Reactor Physics To Leap Forward Reactor Operation and Deployment, 15.-20.05.2022, Pittsburg, USA

Permalink: https://www.hzdr.de/publications/Publ-36607


Data to Impact on various cleaning procedures on p-GaN surfaces

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

Abstract

This folder "XPS data" contains original and evaluated XPS data (.vms) on a p-GaN sample which was treated at various temperatures and underwent Ar+ irradiation.

Furthermore, the folder "REM Images" contains REM images (.tif) and EDX data (.xlsx) on the used excessively treated sample.

All images that are published in the main manuscript are collected as .tif files in the folder "images".

Keywords: damage effects; sputtering damage; surface cleaning; p-GaN; photocathode

Involved research facilities

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-36606


HIFIS - Building a Workshop Portfolio from 0

Erxleben, F.

Abstract

Presentation for the deRSE23 conference, outlining which steps were taken by the HIFIS incubator platform to establish their workshop portfolio, with details on challenges encountered and current state as of February 2023.

Keywords: HIFIS; deRSE23; Education; Indico; GitLab; Hedgedoc

Permalink: https://www.hzdr.de/publications/Publ-36605


From source code to software as a service, how to make software more accessible?

Konrad, U.; Huste, T.; Schnicke, T.; Schäfer, D.; Jandt, U.

Abstract

In the development of software - for products, projects and platforms - different approaches are pursued. For the life cycle of the software, it is important to determine the appropriate approach as early as possible in order to set the framework conditions for software engineering.

Increasingly, scientific software applications are developing into services that are embedded in and used via community platforms. The goal in developing and operating a software platform is to create a sustainable and scalable set of services for a defined target group. Added value compared to local software solutions arises, among other things, from the fact that data storage, computing capacities and communication options are offered in addition to core functions such as modeling, data analysis, project management or software development. The need for continuous operation and development as well as flexible scalability requires special software development methods such as DevOps and CI/CD. The sustainability approach also requires the embedding into scientific communities as well as continuous funding or a viable business model.

Specifics and experiences of this approach will be discussed on the basis of applications from the Helmholtz platform hifis.net.

Keywords: Software; HIFIS; Research Software Engineering; Micro Services; Software Platform

Related publications

  • Open Access Logo Lecture (Conference)
    deRSE23 - Conference for Research Software Engineering in Germany, 20.-22.02.2023, Paderborn, Deutschland
    DOI: 10.5281/zenodo.7653477

Permalink: https://www.hzdr.de/publications/Publ-36604


HIFIS - Boosting Research Software Engineering at Helmholtz

Huste, T.

Abstract

HIFIS, the Helmholtz Federated IT Services, is a Helmholtz-wide platform that supports scientific projects with IT resources, services, consulting and expertise from the collection, storage, linking and analysis of research data to the publication of the results. In addition to offering federated cloud and backbone services, a particular focus is on research software engineering. In recent years, extensive support services have been developed around this topic. The areas of consulting, education, community and technology offerings are covered and help scientists across all of Helmholtz to boost their software engineering practice. The poster will take a look at those offerings, outline the extensive reuse opportunities, and will provide a way to see how such offerings could be transferred to other institutions.

Keywords: HIFIS; Software; RSE; Reproducibility

  • Open Access Logo Poster
    deRSE23 - Conference for Research Software Engineering in Germany, 20.-22.02.2023, Paderborn, Deutschland
    DOI: 10.5281/zenodo.7638538

Permalink: https://www.hzdr.de/publications/Publ-36603


A simulation framework for electrochemical processes with electrolyte flow

Huang, M.; Weber, N.; Mutschke, G.

Abstract

Software tools for simulating electrochemical processes (e.g. COMSOL Multi-physics, ELSYCA) are mostly of commercial type. Besides, three-dimensional simulations in complex cell geometries are known to become resource-expensive, as typically thin concentration boundary layers need to be resolved. The present work presents a simulation framework for electrochemical processes based on the open source platform OpenFOAM. The finite volume method used and combined with domain decomposition is able to efficiently benefit from multicore computer architectures. Our framework takes into account electrolyte flow, which is well known to affect mass transfer, and allows to consider multi-species electrolytes and forcing of the electrolyte. The stability and fast convergence of the method presented is found to rely on the linearization of the Butler-Volmer condi-
tion in the iterative solver. The framework is validated against an analytical solution valid for simplified conditions and an electrodeposition process at a conically shaped electrode in an external magnetic field. The latter exhibits transient departure of the concentration boundary layer from the cathode, and excellent agreement with COMSOL simulation results is found.

Keywords: metal electrodeposition; magnetic field; surface-structured electrode; Lorentz force; Finite Volume Method; Butler-Volmer equation; OpenFOAM

Permalink: https://www.hzdr.de/publications/Publ-36602


Data publication: The evolutionary stability of antagonistic plant facilitation across environmental gradients

Maciel, G. A.; Cabal, C.; Martinez Garcia, R.

Abstract

Set of Python scripts used to produce paper results

Keywords: Ecosystem engineers; Facilitation; Primary sucession; Stress gradient hypothesis; Soil amelioration

Related publications

  • Software in external data repository
    Publication year 2023
    Programming language: Python
    System requirements: The code can be run in any system with Python3
    License: GitHub
    Hosted on GitHub: Link to location
    DOI: 10.5281/zenodo.7634036

Permalink: https://www.hzdr.de/publications/Publ-36601


Metastatic pheochromocytoma and paraganglioma: somatostatin receptor 2 expression, genetics and therapeutic responses

Fischer, A.; Kloos, S.; Maccio, U.; Friemel, J.; Remde, H.; Fassnacht, M.; Pamporaki, C.; Eisenhofer, G.; Timmers, H. J. L. M.; Robledo, M.; Fliedner, S. M. J.; Wang, K.; Maurer, J.; Reul, A.; Zitzmann, K.; Bechmann, N.; Žygienė, G.; Richter, S.; Hantel, C.; Vetter, D.; Lehmann, K.; Mohr, H.; Pellegata, N. S.; Ullrich, M.; Pietzsch, J.; Ziegler, C. G.; Bornstein, S. R.; Kroiss, M.; Reincke, M.; Pacak, K.; Grossman, A. B.; Beuschlein, F.; Nölting, S.

Abstract

Context
Pheochromocytomas/paragangliomas (PPGLs) with pathogenic mutations in the succinate dehydrogenase subunit B (SDHB) are associated with a high metastatic risk. Somatostatin receptor 2 (SSTR2)-dependent imaging is the most sensitive imaging modality for SDHB-related PPGLs, suggesting that SSTR2 expression is a significant cell surface therapeutic biomarker of such tumors.
Objective
Exploration of the relationship between SSTR2 immunoreactivity and SDHB immunoreactivity, mutational status, and clinical behavior of PPGLs. Evaluation of SSTR-based therapies in metastatic PPGLs.
Design
Retrospective analysis of a multicenter cohort of PPGLs.
Setting
Six specialized Endocrine Tumor Centers in Germany, the Netherlands and Switzerland.
Patients
Patients with PPGLs participating in the ENSAT registry.
Methods
Clinical data were extracted from medical records and immunohistochemistry (IHC) for SDHB and SSTR2 was performed in patients with available tumor tissue. Immunoreactivity of SSTR2 was investigated using Volante scores.
Main outcome measure
Association of SSTR2 IHC positivity with genetic and clinic-pathological features of PPGLs.
Results
Of 202 patients with PPGLs, 50% were SSTR2 positive. SSTR2 positivity was significantly associated with SDHB- and SDHx-related PPGLs, with the strongest SSTR2 staining intensity in SDHB-related PPGLs (p=0.01). Moreover, SSTR2 expression was significantly associated with metastatic disease independent of SDHB/SDHx mutation status (p<0.001).
In metastatic PPGLs, the disease control rate with first-line SSTR-based radionuclide therapy was 67% (n=22, n=11 SDHx), and with first-line “cold” somatostatin analogs 100% (n=6, n=3 SDHx).
Conclusions
SSTR2 expression was independently associated with SDHB/SDHx mutations and metastatic disease. We confirm a high disease control rate of somatostatin receptor-based therapies in metastatic PPGLs.

Keywords: Metastatic pheochromocytoma/paraganglioma; SDHB mutation; SDHx mutation; somatostatin receptor 2; somatostatin receptor-based therapies

Permalink: https://www.hzdr.de/publications/Publ-36600


Linear-response time-dependent density functional theory approach to warm dense matter with adiabatic exchange--correlation kernels

Moldabekov, Z.; Pavanello, M.; Boehme, M. P.; Vorberger, J.; Dornheim, T.

Abstract

We present a new methodology for the linear-response time-dependent density functional theory (LR-TDDFT) calculation of the dynamic density response function of warm dense matter in an adiabatic approximation that can be used with any available exchange-correlation (XC) functional across Jacob's Ladder and across temperature regimes. The main novelty of the presented approach is that it can go beyond the adiabatic local density approximation (ALDA) and generalized LDA (AGGA) while preserving the self-consistence between the Kohn-Sham (KS) response function and adiabatic XC kernel for extended systems. The key ingredient for the presented method is the combination of the adiabatic XC kernel from the direct perturbation approach with the macroscopic dynamic KS response from the standard LR-TDDFT method using KS orbitals. We demonstrate the application of the method for the example of warm dense hydrogen, for which we perform a detailed analysis of the KS density response function, the RPA result, the total density response function and of the adiabatic XC kernel. The analysis is performed using LDA, GGA, and meta-GGA level approximations for the XC effects. The presented method is directly applicable to disordered systems such as liquid metals, warm dense matter, and dense plasmas.

Keywords: linear-response time-dependent density functional theory; warm dense matter; warm dense hydrogen

Permalink: https://www.hzdr.de/publications/Publ-36599


Utility of redox-active ligands for reversible multi-electron transfer in uranyl(VI) complexes

Takeyama, T.; Tsushima, S.; Takao, K.

Abstract

In most cases, redox activity of a UO22+ complex is regarded as metal-centered phenomena, because uranium has small energy gaps amongst 5f/6d/7s subshells thereby exhibiting a wide range of oxidation states commonly from +III to +VI or in some instances even +I or +II. While a wide variety of redox-active ligands are known for transition metal complexes including multi-electron reduction that could facilitate inert bond or small molecule activation, only few such examples are known for UO22+. In this study, three UO22+ complexes bearing alpha-diimine-, o-quinonediimine- and 2,6-diiminopyridinebased
ligands were synthesized which exhibited two redox couples in the range from −0.79 V to −2.02 V vs. Fc+/0 to stepwise afford singly- and doubly-reduced complexes. Unique electronic transitions of UO22+ complexes with a manifold of low-lying excited states helped us to complementarily combine spectroelectrochemistry and time-dependent density functional theory (TD-DFT) calculations to assign the redox-active site in these UO22+ complexes, i.e., whether or not a ligand of interest becomes redox-active. During the whole redox processes observed here, the ligands employed are found to be exclusively redox-active, i.e., non-innocent, while the centered UO22+ is just spectating and remains unchanged, i.e., innocent. Whereas double reduction of UO22+ complexes usually involves breakening of strong U≡O bonds, this is not required in the present examples and therefore may find the basis for the synthesis of new types of uranium molecular catalysts and magnetic materials.

Permalink: https://www.hzdr.de/publications/Publ-36598


Fragment molecular orbital (FMO) method for studying actinide-protein interaction

Tsushima, S.

Abstract

In this talk, I will present progress in the research on the use of fragment molecular orbital calculations to the system containing lanthanide and actinide.

  • Invited lecture (Conferences)
    Theory Frontiers in Actinide Science: Chemistry and Materials, 26.02.-01.03.2023, Santa Fe, USA

Permalink: https://www.hzdr.de/publications/Publ-36597


The evolutionary stability of antagonistic plant facilitation across environmental gradients

Cabal, C.; Maciel, G. A.; Martinez Garcia, R.

Abstract

Plant interactions, understood as the net effect of an individual on the fitness of a neighbor, vary in strength and can shift from negative interference to positive facilitation as the environmental conditions change in time and space. However, the biophysical mechanisms underlying these changes are not well understood. Additionally, evolutionary theory questions the stability of antagonistic facilitation. Using a mechanistic model for belowground resource competition between individual plants, we find that, under stress conditions, antagonistic facilitation is evolutionarily stable even when both interacting plants compete for resources. This supports the theory of ecosystem engineers in primary succession and nurse plants in the stress gradient hypothesis. Furthermore, we find that the proportion of the limiting resource that spontaneously becomes available to any plant is the key environmental parameter determining the evolutionary stability of facilitation. This represents a challenge and a potential confusion factor for empirical studies.

Keywords: Ecosystem engineers; Facilitation; Primary sucession; Stress gradient hypothesis; Soil amelioration

Related publications

Permalink: https://www.hzdr.de/publications/Publ-36595


Nonlinear and higher order terms in warm dense matter

Vorberger, J.

Abstract

Higher order correlations influence the physics of the system on many levels. They may be summarized by local field corrections or appear explicitly as non-linear contributions in the density response or in other properties like the stopping power. We present the latest results for nonlinear properties of the electron gas as they have been obtained using real time Green's functions, path integral Monte Carlo, and density functional theory. We show how nonlinear properties can be extracted from simulations with and without external perturbations.

Keywords: warm dense matter; nonlinear response; higher order correlation functions; higher harmonics; x-ray scattering

  • Lecture (Conference)
    43 rd International Workshop on High Energy Density Physics with Intense Ion and Laser Beams, 30.01.-03.02.2023, Hirschegg, Österreich

Permalink: https://www.hzdr.de/publications/Publ-36594


A Lagrangian model for drifting ecosystems reveals heterogeneity-driven enhancement of marine plankton blooms

Ser-Giacomi, E.; Martinez Garcia, R.; Dutkiewicz, S.; Follows, M. J.

Abstract

Marine plankton play a crucial role in carbon storage, oxygen production, global climate, and ecosystem function. Planktonic ecosystems are embedded in a Lagrangian patches of water that are continuously moving, stretching, and diluting. These processes drive inhomegeneities on a range of scales, with implications for the integrated ecosystem properties, but are hard to characterize. We present a theoretical framework which accounts for all these aspects; tracking the water patch hosting a drifting ecosystem along with its physical, environmental, and biochemical features. The model resolves patch dilution and internal physical mixing as a function of oceanic strain and diffusion. Ecological dynamics are parameterized by an idealized nutrient and phytoplankton population and we specifically capture the propagation of the biochemical spatial variances to represent within-patch heterogeneity. We find that, depending only on the physical processes to which the water patch is subjected, the plankton biomass response to a resource perturbation can vary several fold. This work indicates that we must account for these processes when interpreting and modeling marine ecosystems and provides a framework with which to do so.

Permalink: https://www.hzdr.de/publications/Publ-36593


Revealing Non-equilibrium and Relaxation in Laser Heated Matter

Vorberger, J.; Preston, T. R.; Medvedev, N.; Böhme, M.; Moldabekov, Z.; Kraus, D.; Dornheim, T.

Abstract

Experiments creating extreme states of matter almost invariably create non-equilibrium states.
These are very interesting in their own right but need to be understood even if the ultimate goal
is to probe high pressure or high temperature equilibrium properties like the equation of state.
Here, we report on the capabilities of the newly developed imaginary time correlation function
(ITCF) technique [1] to detect and quantify non-equilibrium in pump-probe experiments fielding
time resolved x-ray scattering diagnostics. We find a high sensitivity of the ITCF even to a small
fraction of non-equilibrium electrons in the Wigner distribution. The behavior of the ITCF technique is such that modern lasers and detectors should be able to trace the non-equilibrium relaxation from tens of femto-seconds to several 10s of picoseconds without the need for a model.

Keywords: plasma; warm dense matter; x-ray scattering; non-equilibrium; dynamic structure; imaginary time correlation function; detailed balance

Related publications

Permalink: https://www.hzdr.de/publications/Publ-36592


Dataset to publication: Influence of surface carbon on the performance of cesiated p-GaN photocathodes with high quantum efficiency

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

Abstract

This data repository contains analyzed data files of the shown figures.

Please see the info.txt files in the individual directories and the original manuscript for guidance. Manuscript title: Influence of surface carbon on the performance of cesiated p-GaN photocathodes with high quantum efficiency

Original datasets of the surface study of p-GaN: after wet chemical cleaning, after Cs deposition, during the degradation, and the influence of X-rays on p-GaN:Cs photocathodes. The folder contains datasets from origin, excel and XPS files (.vms) The XPS data were evaluated by using CasaXPS.

Keywords: p-GaN; negative electron affinity surface; XPS; surface cleaning; cesium carbide; quantum efficiency

Involved research facilities

Related publications

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Permalink: https://www.hzdr.de/publications/Publ-36591


Highlight selection of radiochemistry and radiopharmacy developments by editorial board

Kiß, O.; Scott, P.; Behe, M.; Penuelas, I.; Passchier, J.; Rey, A.; Patt, M.; Aime, S.; Jalilian, A.; Laverman, P.; Cheng, Z.; Faivre Chauvet, A.; Engle, J.; Cleeren, F.; Zhu, H.; Vercouille, J.; van Dam, M.; Zhang, M.-R.; Perk, L.; Guillet, B.; Alves, F.

Abstract

Background: The Editorial Board of EJNMMI Radiopharmacy and Chemistry releases a biannual highlight commentary to update the readership on trends in the field of radiopharmaceutical development.
Main Body: This selection of highlights provides commentary on 21 different topics selected by each coauthoring Editorial Board member addressing a variety of aspects ranging from novel radiochemistry to first-in-human application of novel radiopharmaceuticals.
Conclusion: Trends in radiochemistry and radiopharmacy are highlighted. Hot topics cover the entire scope of EJNMMI Radiopharmacy and Chemistry, demonstrating the progress in the research field, and include new PET-labelling methods for 11C and 18F, the importance of choosing the proper chelator for a given radioactive metal ion, implications of total body PET on use of radiopharmaceuticals, legislation issues and radionuclide therapy including the emerging role of 161Tb.

Permalink: https://www.hzdr.de/publications/Publ-36590


Large scale energy storage systems based on SNG and subsurface carbon dioxide storage

Fogel, S.; Unger, S.; Hampel, U.

Abstract

Large-scale energy storage plants based on power-to-gas-to-power (PtG-GtP) technologies incorporating high temperature electrolysis, catalytic methanation for the provision of synthetic natural gas (SNG) and novel, highly efficient SNG-fired Allam reconversion cycles allow for a confined and circular use of CO2/CH4 and thus an emission-free storage of intermittent renewable energy. This study features a thorough technology assessment for large-scale PtG-GtP storage plants based on highly efficient sCO2 power cycles combined with subsurface CO2 storage. The Allam cycle employs supercritical CO2 as working fluid as well as an oxy-combustion process to reach high efficiencies of up to 66 %. The entire PtG-GtP process chain assessed in this study is expected to reach maximum roundtrip efficiencies of 54.2 % (with dedicated and sufficient O2 storage) or 49.0 % (with a dedicated air separation unit). The implementation of said energy storage systems into existing national energy grids will pose a major challenge, since they will require far-reaching infrastructural changes to the respective systems itself, such as extensive installations of renewable generation and electrolysis capacities as well as sufficient subsurface storage capacities for both CO2 and CH4. Therefore, this study incorporates an assessment of the present subsurface storage potential for CO2 and CH4 in Germany. Furthermore, a basic forecast study for the German energy system with an assumed mass deployment of the proposed SNG-based PtG-GtP energy storage system for the year 2050 is conducted. In case of a fully circular use of CO2/CH4, when electricity is solely generated by renewable energy sources, 736 GW of renewables, 234 GW of electrolysis and 62 GW of gas-to-power capacities are required in the best case scenario in 2050. The total storage volume on the national scale of Germany for both CO2 and CH4 was determined to be 7.8 billion Nm3, respectively, leading to a CH4 storage capacity of 54.5 TWh. The presented investigations illustrate the feasibility of large-scale energy storage systems for renewable electricity based on high temperature electrolysis, catalytic methanation and Allam power cycles paired with large subsurface storages for CO2 and CH4.

Keywords: CCUS; CCU; methanation; SOEC; subsurface CO2 storage; sCO2 power cycles; carbon loop; hydrogen storage

Involved research facilities

  • TOPFLOW Facility
  • ROFEX
  • Poster
    Helmholtz Energy Conference, 12.-13.06.2023, Koblenz, Germany

Permalink: https://www.hzdr.de/publications/Publ-36589


DFTB Parameters for the Periodic Table: Part III, Spin-Orbit Coupling

Jha, G.; Heine, T.

Abstract

Spin-orbit coupling (SOC) is crucially important for the correct description of the electronic structure and transport properties of inorganic semiconductors, and for assessing topological properties as in topological insulators. We present a consistent set of SOC parameters for the density-functional based tight-binding (DFTB) method covering the elements throughout the periodic table. The parameters are based on atomic SOC data calculated at the level of density-functional theory (DFT). We tested these parameters for representative systems with significant SOC, including transition metal dichalcogenide two-dimensional crystals, III-V bulk semiconductors, and topological insulators. Our parameterization opens the door for DFTB-based electronic structure and transport calculations of very large systems, such as twisted van der Waals heterostructures.

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Permalink: https://www.hzdr.de/publications/Publ-36588


Data files for determination of inhibitory potency of the published compounds at cathepsins B, L , S and K by fluorimetric activity assay

Löser, R.; Behring, L.

Abstract

archived files (GraphPad prism) containing raw data (time-resolved fluoresence intensities) and associated data analysis for determination of inhibitory potencies

Related publications

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Permalink: https://www.hzdr.de/publications/Publ-36587


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