Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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41419 Publications

Combining Radiation- with Immunotherapy in Prostate Cancer: Influence of Radiation on T cells

Lindner, D.; Arndt, C.; Loureiro, L. R.; Feldmann, A.; Kegler, A.; Koristka, S.; Berndt, N.; Mitwasi, N.; Bergmann, R.; Frenz, M.; Bachmann, M.

Radiation of tumor cells can lead to the selection and outgrowth of tumor escape variants. As radioresistant tumor cells are still sensitive to retargeting of T cells, it appears promising to combine radio- with immunotherapy keeping in mind that the radiation of tumors favors the local conditions for immunotherapy. However, radiation of solid tumors will not only hit the tumor cells but also the infiltrated immune cells. Therefore, we wanted to learn how radiation influences the functionality of T cells with respect to retargeting to tumor cells via a conventional bispecific T cell engager (BiTE) and our previously described modular BiTE format UNImAb. T cells were irradiated between 2 and 50 Gy. Low dose radiation of T cells up to about 20 Gy caused an increased release of the cytokines IL2, TNF and interferon-g and an improved capability to kill target cells. Although radiation with 50 Gy strongly reduced the function of the T cells, it did not completely abrogate the functionality of the T cells.

Keywords: prostate stem cell antigen; prostate cancer; radiation; immunotherapy; bispecific T cell engager

Permalink: https://www.hzdr.de/publications/Publ-34932
Publ.-Id: 34932


Investigation of energy and orientation dependent effects of thimble type ionization detectors in an MRgPT prototype

Fuchs, H.; Gebauer, B.; Hoffmann, A. L.; Pawelke, J.; Lühr, A.; Georg, D.

Introduction
Combining MR imaging and beam delivery for image guided precision radiotherapy was already introduced clinically with hybrid MR-linac systems. For proton therapy, given the conformal treatment method as well as the sensitivity to changes in patient anatomy, a hybrid MR and proton therapy device might be even more beneficial. In Dresden, a clinical demonstrator prototype, consisting of an 0.32 T open MR scanner and a horizontal pencil beam scanning beamline was installed. From a medical phyics perspective, the establishment of reliable dosimetry methods is a prerequisite for further pre-clinical and clinical studies.
In MR guided proton therapy (MRgPT), the primary treatment beam itself is influenced by the magnetic field of the scanner. We investigated whether the response of the dosimetry detector depends on the detector orientation with respect to the magnetic field lines.
In this work we focused on potential effects of the 0.32 T magnetic field on commercially available ionization detectors. For photons, considerable orientation effects have been reported. Given the influence of the magnetic field on the particle trajectories, potential orientation effects could have a considerable influence on dosimetric measurements.
Material & Methods
Experiments were performed at the experimental room of the University Proton Therapy Dresden with and without the prototype MRgPT system positioned 58.2 cm downstream of the beam iso-center of the beam line. Four thimble type ionization detectors, a Farmer, a Semiflex, a PinPoint and a PinPoint 3D detector were positioned at 2 cm water-equivalent depth and irradiated using 10 x 15 cm² homogeneous proton fields. Lateral field shifts due to the vertical magnetic field were compensated for. Irradiations were performed for 3 nominal proton energies (100, 150 and 220 MeV) and repeated with the same set-up at 0.32 T (with MR scanner) and 0 T (MR scanner removed). Chambers were positioned in horizontal, vertical and 15° tilted orientation. Magnetic field correction factors were evaluated.

Results
Preliminary results show a small orientation dependence within 0.3 and 1% depending on the chamber, with larger effects for smaller chamber volumes.
A small, but consistent energy dependence of the magnetic field correction factor ranging from 0.5 to 1.6% was determined. The change in correction factors was found to be higher for lower energies as well as smaller sensitive detector volumes.

Discussion
Chamber readings inside an applied magnetic field of 0.32 T were found to depend on detector orientation as well as incident proton energy. For 0 T no noticeable influence was determined. In addition, the effect seems to be more pronounced for small volume chambers. Especially for small volume chambers, such as the PinPoint 3D, it is recommended to introduce a respective correction factor.

Keywords: chamber dosimetry; thimble chamber; proton; MRI; MRgPT; MRiPT; chamber correction factor; energy; orientation

  • Lecture (Conference)
    3 Verbände – Strahlenschutztagung, 29.09.-01.10.2022, Wien, Österreich

Permalink: https://www.hzdr.de/publications/Publ-34931
Publ.-Id: 34931


Dataset for Diamond formation kinetics in shock-compressed C-H-O samples recorded by small-angle X-ray scattering and X-ray diffraction

Kraus, D.

Dataset for publication "Diamond formation kinetics in shock-compressed C-H-O samples recorded by small-angle X-ray scattering and X-ray diffraction"

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Permalink: https://www.hzdr.de/publications/Publ-34930
Publ.-Id: 34930


A FAIRly Integrated Scientific Project Lifecycle

Knodel, O.; Voigt, M.; Ufer, R.; Pape, D.; Lokamani, M.; Kelling, J.; Müller, S.; Gruber, T.; Juckeland, G.; Kessler, A.; Hein, J.; Schuller, B.

The talk introduces the general idea behind the HELIPORT project, which aims to make the entire life cycle of a scientific experiment or project discoverable, accessible, interoperable and reusable by providing an overview from a top-level perspective. Specifically, our data management solution addresses the areas from data generation to publication of primary research data, computing workflows performed and the actual research results.

Keywords: Data Management; Metadata; FAIR; Data provenance; Digital Objects; Digital Twins

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    HMC Dialogue, 15.07.2022, online, Germany

Permalink: https://www.hzdr.de/publications/Publ-34929
Publ.-Id: 34929


Broken axial symmetry as essential feature for a consistent modelling of various observables in heavy nuclei

Grosse, E.; Junghans, A.

Although most nuclear spectroscopy as well as atomic hyperfine structure data do not deliver accurate information on nuclear
axiality the ad-hoc assumption of symmetry about one axis found widespread use in nuclear model calculations. In the theoretical
interpretation of nuclear properties as well as in the analysis of experimental data triaxiality was considered – if at all – only
for some, often exotic, nuclides. A breaking of axial symmetry combined to a spin-independent moment of inertia results in a
surprisingly simple heuristic triaxial parametrization of the yrast sequence in all heavy nuclei, including well deformed ones. No
additional fit parameters are needed in detailed studies of the mass and charge dependence of the electric dipole strength in the range
of and outside of giant dipole resonances. Allowing triaxiality also avoids the introduction of an arbitrary level density parameter
˜a to fit the accurate values observed in n-capture experiments and ˜a can be taken from nuclear matter studies. A combination of
this value to the yrast energies no longer based on axiality and the related I(I+1) rule results in agreement to data independent of
spin. And predictions for radiative neutron capture as derived on the basis of non-axiality are improved as well. The experimentally
favoured broken axial symmetry is in accord to HFB and MC-shell model calculations already for nuclei in the valley of stability.

Permalink: https://www.hzdr.de/publications/Publ-34928
Publ.-Id: 34928


Modulating the pharmacokinetic profile of Actinium-225-labeled macropa-derived radioconjugates by dual targeting of PSMA and albumin

Reissig, F.; Zarschler, K.; Novy, Z.; Petrik, M.; Bendova, K.; Kurfurstova, D.; Bouchal, J.; Ludik, M.-C.; Brandt, F.; Kopka, K.; Khoylou, M.; Pietzsch, H.-J.; Hajduch, M.; Mamat, C.

Rationale: Small 225Ac-labeled prostate-specific membrane antigen (PSMA)-targeted radioconjugates have been described for targeted alpha therapy of metastatic castration-resistant prostate cancer. Transient binding to serum albumin as a highly abundant, inherent transport protein represents a commonly applied strategy to modulate the tissue distribution profile of such low-molecular-weight radiotherapeutics and to enhance radioactivity uptake into tumor lesions with the ultimate objective of improved therapeutic outcome.
Methods: Two ligands mcp-M-alb-PSMA and mcp-D-alb-PSMA were synthesized by combining a macropa-derived chelator with either one or two lysine-ureido-glutamate–based PSMA- and 4-(p-iodophenyl)butyrate albumin-binding entities using multistep peptide-coupling chemistry. Both compounds were labeled with [225Ac]Ac3+ under mild conditions and their reversible binding to serum albumin was analyzed by an ultrafiltration assay as well as microscale thermophoresis measurements. Saturation binding studies and clonogenic survival assays using PSMA-expressing LNCaP cells were performed to evaluate PSMA-mediated cell binding and to assess the cytotoxic potency of the novel radioconjugates [225Ac]Ac-mcp-M-alb-PSMA and [225Ac]Ac-mcp-D-alb-PSMA, respectively. The biodistribution of both 225Ac-radioconjugates was investigated in LNCaP tumor-bearing SCID mice. Histological examinations of selected organs were performed to analyze the occurrence of necrosis using H&E staining, DNA damage via γH2AX staining and proliferation via Ki67 expression in the tissue samples.
Results: Enhanced binding to serum components in general and to human serum albumin in particular was revealed for [225Ac]Ac-mcp-M-alb-PSMA and [225Ac]Ac-mcp-D-alb-PSMA, respectively. Moreover, the novel derivatives are highly potent PSMA ligands as their KD values in the nanomolar range (23.38 and 11.56 nM) are comparable to the reference radioconjugates [225Ac]Ac-mcp-M-PSMA (30.83 nM) and [225Ac]Ac-mcp-D-PSMA (10.20 nM) without albumin binders. The clonogenic activity of LNCaP cells after treatment with the 225Ac-labeled ligands was affected in a dose- and time-dependent manner, whereas the dimeric radioconjugate [225Ac]Ac-mcp-D-alb-PSMA has a stronger impact on the clonogenic cell survival than its monomeric counterpart [225Ac]Ac-mcp-M-alb-PSMA. Biodistribution studies performed in LNCaP tumor xenografts showed prolonged blood circulation times for both albumin-binding radioconjugates and a substantially increased tumor uptake (46.04 ± 7.77 %ID/g for [225Ac]Ac-mcp-M-alb-PSMA at 128 h p.i. and 153.48 ± 37.76 %ID/g at 168 h p.i. for [225Ac]Ac-mcp-D-alb-PSMA) with favorable tumor-to-background ratios. Consequently, a clear histological indication of DNA damage was discovered in the tumor tissues, whereas DNA double-strand break formation in kidney and liver sections was less pronounced.
Conclusion: The modification of the PSMA-based 225Ac-radioconjugates with one or two albumin-binding entities resulted in an improved radiopharmacological behavior including a greatly enhanced tumor accumulation combined with a low to neglectable uptake in non-targeted organs.

Keywords: Macropa; Actinium; Targeted Alpha Therapy; Albumin Binder; PSMA

Permalink: https://www.hzdr.de/publications/Publ-34927
Publ.-Id: 34927


Curvilinear magnetism: fundamentals and applications

Makarov, D.

In this talk I provide an overview of the activities of the FWID department with the focus on curvature effects in magnetic thin films and realization of flexible magnetic field sensors.

Keywords: curvature effects in magnetism; curvilinear magnetism; magnetic field sensing; human-machine interfaces; soft robotics

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  • Lecture (others)
    Invited talk at the Leibniz IFW (Institute for Metalic Materials), 12.07.2022, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-34926
Publ.-Id: 34926


Neuromorphic computing with magnons

Schultheiß, K.

Within the last decade, spintronics and magnonics have demonstrated an impressive development in the experimental realization of Boolean logic gates. However, the exponential growth of data and the rise of the internet of things are pushing the deterministic Boolean computing of von-Neumann architectures to their limits or are simply to energy consuming. Moreover, it is accepted commonly that conventional Boolean computer architectures are likely to remain inefficient for certain cognitive tasks in which the human brain excels, such as pattern recognition, particularly when incomplete or noisy data are involved.
One of the most generic and abstract implementations of brain-inspired computing schemes is reservoir computing, where the nonlinear response of a physical system is used to separate patterns hidden in a temporal data stream into distinct manifolds of a higher dimensional output space. In this presentation, I will demonstrate the experimental realization of pattern recognition based on reservoir computing using magnons.
Recently, we reported on the nonlinear scattering of magnons in vortices in micron-sized Permalloy discs [1] which we also learned to control and stimulate by means of other magnons [2]. Now, we utilize these phenomena to employ magnons for pattern recognition without actually relying on magnon transport in real space. I will present a comprehensive overview of experimental results and numerical simulations demonstrating the capabilities and advantages of magnon reservoir computing in reciprocal space.

[1] K. Schultheiss, et al., Physical Review Letters 125, 207203 (2020)
[2] K. Schultheiss, et al., Physical Review Letters 122, 097202 (2019)

Keywords: spin waves; magnonics; reservoir computing; Brillouin light scattering

Related publications

  • Invited lecture (Conferences)
    CMD29 Conference, 22.8.2022, Manchester, United Kingdom
  • Invited lecture (Conferences)
    7th Workshop on Magnonics, 1.8.2022, Oxnard, Kalifornien, USA

Permalink: https://www.hzdr.de/publications/Publ-34924
Publ.-Id: 34924


Simple Growth–Metabolism Relations Are Revealed by Conserved Patterns of Heat Flow from Cultured Microorganisms

Fahmy, K.

Quantitative analyses of cell replication address the connection between metabolism and growth. Various growth models approximate time-dependent cell numbers in culture media, but physio-logical implications of the parametrizations are vague. In contrast, isothermal microcalorimetry (IMC) measures with unprecedented sensitivity to heat (enthalpy) release via chemical turnover in metabolizing cells. Hence, the metabolic activity can be studied independently of modeling the time-dependence of cell numbers. Unexpectedly, IMC traces of various origins exhibit conserved patterns when expressed in the enthalpy domain rather than the time domain, as exemplified by cultures of Lactococcus lactis (prokaryote), Trypanosoma congolese (protozoan) and non-growing Brassica napus (plant) cells. The data comply extraordinarily well with a dynamic Langmuir ad-sorption reaction model of nutrient uptake and catalytic turnover generalized here to the non-constancy of catalytic capacity. Formal relations to Michaelis–Menten kinetics and common analytical growth models are briefly discussed. The proposed formalism reproduces the “life span” of cultured microorganisms from exponential growth to metabolic decline by a succession of distinct metabolic phases following remarkably simple nutrient–metabolism relations. The analysis enables the development of advanced enzyme network models of unbalanced growth and has fundamental consequences for the derivation of toxicity measures and the transferability of metabolic activity data between laboratories.

Keywords: bacteria; enzyme kinetics; heavy metals; isothermal microcalorimetry; Michaelis–Menten; toxicity

Permalink: https://www.hzdr.de/publications/Publ-34922
Publ.-Id: 34922


The Open-Access European Prevention of Alzheimer’s Dementia (EPAD) MRI dataset and processing workflow

Lorenzini, L.; Ingala, S.; Wink, A. M.; Kuijer, J. P. A.; Wottschel, V.; Dijsselhof, M.; Sudre, C. H.; Haller, S.; Molinuevo, J. L.; Gispert, J. D.; Cash, D. M.; Thomas, D. L.; Vos, S. B.; Prados, F.; Petr, J.; Wolz, R.; Palombit, A.; Schwarz, A. J.; Chételat, G.; Payoux, P.; Di Perri, C.; Wardlaw, J. M.; Frisoni, G. B.; Foley, C.; Fox, N. C.; Ritchie, C.; Pernet, C.; Waldman, A.; Barkhof, F.; Mutsaerts, H. J. M. M.

The European Prevention of Alzheimer Dementia (EPAD) is a multi-center study that aims to characterize the
preclinical and prodromal stages of Alzheimer’s Disease. The EPAD imaging dataset includes core (3D T1w, 3D
FLAIR) and advanced (ASL, diffusion MRI, and resting-state fMRI) MRI sequences.
Here, we give an overview of the semi-automatic multimodal and multisite pipeline that we developed to
curate, preprocess, quality control (QC), and compute image-derived phenotypes (IDPs) from the EPAD MRI
dataset. This pipeline harmonizes DICOM data structure across sites and performs standardized MRI pre-
processing steps. A semi-automated MRI QC procedure was implemented to visualize and flag MRI images next to
site-specific distributions of QC features — i.e. metrics that represent image quality. The value of each of these
QC features was evaluated through comparison with visual assessment and step-wise parameter selection based
on logistic regression. IDPs were computed from 5 different MRI modalities and their sanity and potential clinical
relevance were ascertained by assessing their relationship with biological markers of aging and dementia.
The EPAD v1500.0 data release encompassed core structural scans from 1356 participants 842 fMRI, 831
dMRI, and 858 ASL scans. From 1356 3D T1w images, we identified 17 images with poor quality and 61 with
moderate quality. Five QC features — Signal to Noise Ratio (SNR), Contrast to Noise Ratio (CNR), Coefficient of
Joint Variation (CJV), Foreground-Background energy Ratio (FBER), and Image Quality Rate (IQR) — were
selected as the most informative on image quality by comparison with visual assessment. The multimodal IDPs
showed greater impairment in associations with age and dementia biomarkers, demonstrating the potential of
the dataset for future clinical analyses.

Permalink: https://www.hzdr.de/publications/Publ-34920
Publ.-Id: 34920


Data publication: Electronic Density Response of Warm Dense Hydrogen: Ab initio Path Integral Monte Carlo Simulations

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

This repository contains the PIMC raw data for the static electronic density response of warm dense hydrogen. Units etc are the same as in the figures in the main text / supplemental material.

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Permalink: https://www.hzdr.de/publications/Publ-34919
Publ.-Id: 34919


Atomic mechanisms of self-diffusion in amorphous silicon

Posselt, M.; Bracht, H.; Ghorbani Asl, M.; Radić, D.

Based on recent calculations of the self-diffusion (SD) coefficient in amorphous silicon (a-Si) by classical Molecular Dynamics simulation [M. Posselt, H. Bracht, and D. Radić, J. Appl. Phys. 131, 035102 (2022)] detailed investigations on atomic mechanisms are performed. For this purpose two Stillinger-Weber-type potentials are employed, one strongly overestimates the SD coefficient, while the other leads to values much closer to the experimental data. By taking into account the individual squared displacements (or diffusion lengths) of atoms the diffusional and vibrational contributions to the total mean squared displacement can be determined separately. It is shown that the diffusional part is not directly correlated with the concentration of coordination defects. The time-dependent distribution of squared displacements of atoms indicates that in a-Si a well-defined elemental diffusion length does not exist, in contrast to SD in the crystalline Si. The analysis of atoms with large squared displacements reveals that the mechanisms of SD in a-Si are characterized by complex rearrangement of bonds or exchange of neighbors. These are mono- and bi-directional exchanges of neighbors and neighbor replacements. Exchange or replacement may concern up to three neighbors and may occur in relatively short periods of some ps. Bi- or mono-directional exchange or replacement of one neighbor atom happen more frequently than processes including more neighbors. A comparison of results for the two interatomic potentials shows that an increased three-body parameter only slows down the migration, but does not change the migration mechanisms fundamentally.

Keywords: Amorphous silicon; Self-diffusion; Atomistic simulation; Atomic mechanisms

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Permalink: https://www.hzdr.de/publications/Publ-34918
Publ.-Id: 34918


Equivariant neural networks for image segmentation

Venkatesh, D. K.; Lokamani, M.; Juckeland, G.; Weigert, M.; Steinbach, P.

Deep neural networks have by today been established as the goto candidate for semantic or instance segmentation at many scales and image modalities. The pressing challenge in supervised segmentation approaches remains to be the requirement of large annotated image datasets for good performance.
In recent years the expressive capabilities of neural networks have been demonstrated to improve through group convolutional operations which exploit existing symmetries present in the data.
The increased capacity for weight-sharing alongside gains in sample efficiency for training a neural network have led to the empirical success of equivariant neural networks. In our study, we propose and experiment on an equivariant U-net-based model for the task of image segmentation. In this talk, we will discuss our preliminary results on a synthetic datasets consisting of polygonal objects. The results indicate that the performance of our implementation of an equivariant network improves well beyond a vanilla Unet when exposed to symmetrical objects in data different scenarios.

References:

1. Taco S. Cohen, Max Welling, “Group Equivariant convolution networks”, arXiv preprint arXiv: 1602.07576, 2016.
2. Maurice Weiler and Gabriele Cesa, ”General E(2)-Equivariant Steerable CNNs”, NeurIPS 2019.

Keywords: equivariant neural networks; image segmentation; data augmentation; group theory; symmetry

  • Open Access Logo Lecture (Conference)
    Swiss Equivariant Learning Workshop, 11.-14.07.2022, Lausanne, Schweiz

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Permalink: https://www.hzdr.de/publications/Publ-34917
Publ.-Id: 34917


Evolution of elctronic coupling in the mechanically controllable break junctions

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

The electrical properties of single molecules can be investigated using atomically sharp metallic electrodes in mechanically controllable break junctions (MCBJs). The current-voltage (IV) characteristics of single molecules in such junctions are influenced by the binding positions of the end groups on the tip-facets and tip-tip separation. In this talk, we present MCBJ experiments on N,N’-Bis(5-ethynylbenzenethiol-salicylidene)ethylenediamine (Salen). We discuss the evolution of the single level model (SLM) parameters namely, a) the energetic level є of the dominant conducting channel and b) the coupling Γ of the dominant conducting channel to the metallic electrodes. The SLM-parameters were evaluated for IV-curves recorded during opening measurements and fitted to the single level model. We propose a novel, high-throughput approach to model the evolution of the SLM-parameters and explain the recurring peak-like features in the experimentally measured evolution of Γ with increasing tip-tip separation, which we relate to the deformation of the molecule and the sliding of the anchor group above the electrode surface.

Keywords: MCBJ; Single Level Model; high-throughput approach; evolution of the SLM-parameters

  • Open Access Logo Lecture (Conference)
    DPG Regensburg 2022, 04.-09.09.2022, Regensburg, Germany

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Permalink: https://www.hzdr.de/publications/Publ-34916
Publ.-Id: 34916


The effect of composition and microstructure on the creep behaviour of 14 Cr ODS steels consolidated by SPS

Meza, A.; Macía, E.; Chekhonin, P.; Altstadt, E.; Rabanal, M. E.; Torralba, J. M.; Campos, M.

There is a general need for alternative structural materials to improve power plants' efficiency and reduce CO2 emissions. Within this framework, two new compositions of temperature-resistant sintered ODS ferritic steels (14Cr-5Al-3W), strengthened by a fine dispersion of precipitates (5·1022 ox. /m3), have been developed. This work focuses on creep properties and microstructure evolution. The creep resistance (at 650°C) could be improved by prior microstructural optimisation, thanks to the consolidation by spark plasma sintering and the tailoring of precipitates' nature when a single compound introduces the oxide-forming elements (Y-Ti-Zr-O) synthesised for this purpose. To this end, the initial pre-alloyed ferritic powder was mechanically alloyed with the synthesised compound and sintered by spark plasma sintering (SPS). Afterwards, EBSD and TEM characterisation were employed to study the microstructures. Small punch creep tests (SPCT) were performed on the steels to analyse their creep performance. These showed an exceptional enhancement of the creep resistance in the steels containing the Y-Ti-Zr-O additions.

Keywords: 14Cr-ODS steel; fine grain; creep behaviour; SPCT

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Permalink: https://www.hzdr.de/publications/Publ-34915
Publ.-Id: 34915


Investigation of particle effects on bubble coalescence in slurry with a chimera MP-PIC and VOF coupled method

Liao, Y.; Wang, Q.; Caliskan, U.; Miskovic, S.

Bubble coalescence and breakup is still a complex challenging topic. How far it is understood affects directly the analysis and design optimization of multiphase reactors. Despite years of active research, bubble coalescence in three-phase systems is far from being understood. Contradictory
results on the effect of particles are often reported. Although it still lacks a unique explanation, a general conjecture is that the presence of solid particles affects the film drainage process, and hence the bubble coalescence time and behaviour. This paper presents insights into bubble-pair coalescence in slurry by coupling the multiphase particle in cell (MP-PIC) method with the volume of fluid (VOF) method. The mesh resolution for VOF fields is down to micrometers, which allows for analysis of the film drainage and rupture mechanism in detail. The accuracy of MP-PIC fields during the refinement of CFD grids is guaranteed by a chimera approach (Caliskan and Miskovic, Chemical Engineering Journal Advances 5 (2021) 100054), which allows two overlapping meshes in the Lagrangian-Eulerian framework, namely, a fine mesh for the CFD fields and a coarser mesh for the MP-PIC ones.

Keywords: Bubble coalescence; Chimera grid; MP-PIC and VOF coupled; Particle effects; Slurry

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Permalink: https://www.hzdr.de/publications/Publ-34914
Publ.-Id: 34914


Presence of uranium(V) during uranium(VI) reduction by Desulfosporosinus hippei DSM 8344T

Hilpmann, S.; Roßberg, A.; Steudtner, R.; Drobot, B.; Hübner, R.; Bok, F.; Prieur, D.; Bauters, S.; Kvashnina, K.; Stumpf, T.; Cherkouk, A.

Microbial U(VI) reduction influences the uranium mobility in contaminated subsurface environments and can affect the disposal of high-level radioactive waste by transform-ing the water-soluble U(VI) to less mobile U(IV). The reduction of U(VI) by the sulfate-reducing bacterium Desulfosporosinus hippei DSM 8344T, a close phylogenetic relative to naturally occurring microorganism present in clay rock and bentonite, was investigat-ed. D. hippei DSM 8344T showed a relatively fast removal of uranium from the superna-tants in artificial Opalinus Clay pore water. Combined speciation calculations and lumi-nescence spectroscopic investigations showed the dependence of U(VI) reduction on the initial U(VI) species. Scanning transmission electron microscopy coupled with ener-gy-dispersive X-ray spectroscopy showed uranium-containing aggregates on the cell surface and the formation of membrane vesicles. By combining different spectroscopic techniques, including UV/Vis spectroscopy, as well as uranium M4-edge X-ray absorp-tion near-edge structure (XANES) recorded in high-energy-resolution fluorescence-detection (HERFD) mode and extended X-ray absorption fine structure (EXAFS) analy-sis, the partial reduction of U(VI) could be verified, whereby the formed U(IV) product has an unknown structure. Furthermore, the U M4 HERFD-XANES showed the presence of U(V) during the process, suggesting a single-electron transfer mechanism for the microbial U(VI) reduction by sulfate reducers. These findings offer new insights into the U(VI) reduction by sulfate-reducing bacteria and contribute to a comprehensive safety concept for a repository for high-level radioactive waste.

Keywords: Uranium(VI) reduction; Sulfate-reducing bacteria; Opalinus Clay pore water; Pentavalent uranium; Membrane vesicles

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Permalink: https://www.hzdr.de/publications/Publ-34911
Publ.-Id: 34911


Euler-Euler CFD simulation of high velocity gas injection at pool scrubbing conditions

Li, S.; Apanasevich, P.; Lucas, D.; Liao, Y.

Pressure relief by blowdown is one of the most important measures to prevent excessive pressures in the primary circuit or containment in the event of severe nuclear accidents. Pool scrubbing can significantly reduce the release of radioactive materials, e.g. aerosols, to the environment during the pressure relief. The decontamination factor indicating the particle retention efficiency depends, among other factors, on the hydrodynamic conditions of the gas-liquid two-phase flow inside the pool. In the present work, the hydrodynamics in two typical pool scrubbing experiments is investigated with the two-fluid bubbly flow model, and the influence of some key factors including bubble diameter, nozzle submergence as well as interaction models is analysed. One case is a rectangular pool and the other is a cylindrical column, and their injection Weber number is around 2×103 and 4×105, respectively. The numerical results show that the void fraction and velocity field expand from the central region where the nozzle is located to the whole cross section, as the distance from the nozzle exit increases. The profile as well as its development depends largely on the bubble size and the interaction force model. It reveals that in the monodisperse simulation the tuning of bubble diameter is necessary for achieving good agreement, which is however awkward for high velocity gas injection. More information is required for properly describing the bubble size distribution as well as its evolution in pool scrubbing conditions. Furthermore, the experimental data show clear drag reduction in the bubble swarm generated by the gas jet, and further investigations on the mechanism and model improvement have to be done.

Keywords: Decontamination factor; Hydrodynamics; OpenFOAM; Pool scrubbing; Two-fluid model

Permalink: https://www.hzdr.de/publications/Publ-34910
Publ.-Id: 34910


Electrode design of an electrical impedance spectroscopy system for fouling detection in a heat exchanger

de Assis Dias, F.; Schubert, M.; Schleicher, E.; Scholz, F.; Hampel, U.

We present a preliminary study of the electrode design of an electrical impedance spectroscopy (EIS) system for fouling detection in heat exchangers. In this study, a basic model of a heat exchanger is created based on finite element method (FEM). Here, an invasive and non-invasive electrode configuration was investigated. Numerical results show that both invasive and non-invasive electrode configurations are suitable for detecting fouling using impedance spectroscopy. The invasive one showed a better contrast between the fouling and non-fouling scenarios. However, from a practical point of view, the latter is preferable in our application since it does not disturb the surface where fouling is formed.

Keywords: electrical impedance spectroscopy; fouling; crystallization scale; heat exchanger

  • Contribution to proceedings
    8th International Conference on Sensors and Electronic Instrumentation Advances (SEIA 2022), 21.-23.09.2022, Corfu, Greece
    ISSN: 978-84-09-43854-9
  • Poster
    8th International Conference on Sensors and Electronic Instrumentation Advances, 21.-23.09.2022, Corfu, Greece
    ISSN: 978-84-09-43854-9

Permalink: https://www.hzdr.de/publications/Publ-34909
Publ.-Id: 34909


Electrical impedance spectroscopy for fouling detection in heat exchangers with earth connected working electrodes

de Assis Dias, F.; Schubert, M.; Schleicher, E.; Pelzs, P.-L.; Meyer, C.; Bulst, M.; Hampel, U.

We created a test cell to design a measurement system based on electrical impedance spectroscopy for heat exchangers. In the experimental heat exchanger, the working electrode is connected to the earth potential for safety reasons. To avoid short-circuiting, an isolation transformer to decouple the impedance analyzer from earth potential was used, thus allowing the detection and characterization of thin fouling layers even if the working electrode is still connected to earth.

Keywords: electrical impedance spectroscopy; fouling; heat exchanger

  • Contribution to proceedings
    International Workshop on Impedance Spectroscopy (IWIS), 27.-30.09.2022, Chemnitz, Deutschland
    2022 International Workshop on Impedance Spectroscopy (IWIS)
    DOI: 10.1109/IWIS57888.2022.9975121
  • Lecture (Conference) (Online presentation)
    15th International Workshop on Impedance Spectroscopy, 27.-30.09.2022, Chemnitz, Germany

Permalink: https://www.hzdr.de/publications/Publ-34908
Publ.-Id: 34908


Modelling and Performance Analysis of Hydrocyclones: The Case of Buzwagi Gold Mine

Wikedzi, A.; Mütze, T.

The performance of hydrocyclones at Buzwagi Gold Mine (BGM) was investigated in three full scale survey campaigns. Thereafter, several empirical and theoretical hydrocyclone models were used for prediction of hydrocyclone performance. The survey data revealed poor performance of the grinding circuit caused by a circulating load higher than the design. Further, the poor performance of the grinding circuit had consequences on hydrocyclones overflow particle size (i.e. a much coarser product, xP,80 > 200 µm) than target (125 µm). In addition, the operation indicates overloading of the hydrocyclones due to feed rates being 10–18% above the design capacity. Apart from their deficiencies, BGM hydrocyclones can be categorized as very good or excellent separators in terms of separation efficiency based on partition curves, T(x). The modelling of BGM hydrocyclones revealed that Nageswararao’s model can well describe and predict the operation and is recommended for future simulation and optimization of the operation. Based on the survey data, there are opportunities to improve current operation through adjustment of operating conditions like dilution of hydrocyclone feed for improved classification efficiency.

Keywords: Grinding circuit; Hydrocyclone performance; Partition curve; Hydrocyclone Modelling

Permalink: https://www.hzdr.de/publications/Publ-34907
Publ.-Id: 34907


Data publication: CMOS-compatible manufacturability of sub-15 nm Si/SiO2/Si nanopillars containing single Si nanodots for single electron transistor applications

von Borany, J.; Engelmann, Hans-Jürgen; Heinig, K.-H.; Hlawacek, G.; Hübner, R.; Klüpfel, F.; Möller, W.; Pourteau, M.-L.; Rademaker, G.; Rommel, M.; Baier, L.; Pichler, P.; Tiron, R.

The data included in the publication are results of SET device simulations, Monte-Carlo simulations of physical processes (ion-beam mixing, phase seepration, Si nanodot formation) and micrographs taken by electron and ion microscopes.

Keywords: CMOS; Single-electron transistor; nanostructure fabrication; self-organization; Silicon nanodot; Nanopillars; Ion-beam mixing; Phase separation

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Permalink: https://www.hzdr.de/publications/Publ-34906
Publ.-Id: 34906


Stability theory for metal pad roll in cylindrical liquid metal batteries

Herreman, W.; Wierzchalek, L.; Horstmann, G. M.; Cappanera, L.; Nore, C.

When liquid metal batteries are charged or discharged, strong electrical currents are
passing through the three liquid layers that we find in their interior. This may result in
the metal pad roll instability that drives gravity waves on the interfaces between the layers.
In this paper, we investigate theoretically metal pad roll instability in idealised cylindrical
liquid metal batteries that were simulated previously by Weber et al. (Phys. Fluids, vol.
29, no. 5, 2017b, 054101) and Horstmann et al. (J. Fluid Mech., vol. 845, 2018, pp. 1–35).
Near the instability threshold, we expect weakly destabilised gravity waves, and in this
parameter regime, we can use perturbation methods to find explicit formulas for the growth
rate of all possible waves. This perturbative approach also allows us to include dissipative
effects, hence we can locate the instability threshold with good precision. We show that
our theoretical growth rates are in quantitative agreement with previous and new direct
numerical simulations. We explain how our theory can be used to estimate a lower bound
on cell size beneath which metal pad roll instability is unlikely.

Keywords: MHD and Electrohydrodynamics; Waves/Free-surface Flows

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  • Secondary publication expected from 26.04.2024

Permalink: https://www.hzdr.de/publications/Publ-34905
Publ.-Id: 34905


Data publication: ExponatONE: a high-precision small animal irradiation setup using proton radiography

Schneider, M.; Elisabeth, B.; Suckert, T.; Beyreuther, E.; Bock, J.; Dietrich, A.; Gantz, S.; Heuchel, L.; Krause, M.; von Neubeck, C.; Nexhipi, S.; Tillner, F.; Schürer, M.; Lühr, A.; Müller, J.

Daten, die für die Veröffentlichung "ExponatONE: eine hochpräzise Kleintierbestrahlungsanlage mit Protonenradiographie" verwendet wurden.
Das Repository enthält alle Daten, die zur Erstellung der quantitativen Ergebnisse und Abbildungen im eingereichten Manuskript verwendet wurden.
Satz von Skripten zur Aufnahme und Verarbeitung von Radiografiebildern/CTs, wie im zugehörigen Paper beschrieben.
Bei dem Datensatz handelt es sich um alle verwendeten Bilder und Grafen (CT, Röntgenbilder, Radiografiebilder, Simulationen, Mikroskopiebilder) für die Auswertung der Ergebnisse und die Darstellung in den Figures.

Keywords: Proton therapy; Proton radiography; Mouse brain irradiation; Preclinical high-precision setup; DNA damage; Relative biological effectiveness (RBE)

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Permalink: https://www.hzdr.de/publications/Publ-34904
Publ.-Id: 34904


Shedding light on the enigmatic TcO₂·xH₂O structure with density functional theory and EXAFS spectroscopy

Faria Oliveira, A.; Kuc, A. B.; Heine, T.; Abram, U.; Scheinost, A.

The β-emitting 99Tc isotope is a high-yield fission product in 235U and 239Pu nuclear reactors, raising special concern in nuclear waste management due to its long half-life and the high mobility of pertechnetate (TcO4−). In the conditions of deep nuclear waste repositories, retention of Tc is achieved via biotic and abiotic reduction of TcO4− to compounds like amorphous TcO2·xH2O precipitates. It is generally accepted that these precipitates have linear (Tc(μ O)2(H2O)2)n chains, with trans H2O. Although corresponding Tc Tc and Tc O distances have been obtained from Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy, this structure is largely based on analogy with other compounds. Here, we combine Density-Functional Theory with EXAFS measurements of fresh and aged samples to show that, instead, TcO2·xH2O forms zigzag chains that undergo a slow aging process whereby they combine to form longer chains and, later, a tridimensional structure that might lead to a new TcO2 polymorph.

Keywords: Chain structures; Density functional calculations; EXAFS spectroscopy; Nuclear waste management; Technetium

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Permalink: https://www.hzdr.de/publications/Publ-34903
Publ.-Id: 34903


Data publication: Application of the Coordinate Transformation in Nodal Diffusion Calculations of Radially Expanding SFR Cores

Nikitin, E.; Fridman, E.

DYN3D calculations (inputs + outputs).

Keywords: DYN3D; Nodal methods; Serpent; SFR; Thermal expansion

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Permalink: https://www.hzdr.de/publications/Publ-34900
Publ.-Id: 34900


Cyclotron production of ⁹⁵Nb using a natZr solid target

Franke, K.; Mansel, A.

⁹⁴Nb (half-life of 2.03x10⁴ a) is part of the radioactive inventory of the waste in the dismantling process of nuclear power plants. Half-life (34.991 d) and decay mode point out ⁹⁵Nb as appropriate isotopic radiotracer to investigate the fate of ⁹⁴Nb in future waste repositories.

Keywords: cyclotron; solid target; ⁹⁵Nb; niobium radionuclide

  • Poster
    Nuklearchemie 2022, 04.-06.10.2022, Bergisch Gladbach, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34899
Publ.-Id: 34899


Application of the Coordinate Transformation in Nodal Diffusion Calculations of Radially Expanding SFR Cores

Nikitin, E.; Fridman, E.

In this study, the coordinate transformation technique was assessed for radial expansion of Sodium cooled Fast Reactor (SFR) cores with the focus on time-dependent calculations. This method was implemented into nodal diffusion code DYN3D and was tested against the already available direct mesh expansion model. The newly implemented method was tested for uniform radial core expansion cases. Within DYN3D, the coordinate transformation method was verified on steady-state cases and was validated on one of the transient scenarios from the Phenix reactor experiments. The obtained results demonstrate equivalence between the coordinate transformation and direct mesh expansion techniques and therefore presenting the viability of the former one in transient calculations of SFR cores.

Keywords: DYN3D; Nodal methods; Serpent; SFR; Thermal expansion

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  • Contribution to proceedings
    2019 International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering, M&C 2019, 25.-29.08.2019, Portland, USA, 978-089448769-9, 1624-1631
  • Lecture (Conference)
    2019 International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering, M&C 2019, 25.-29.08.2019, Portland, USA

Permalink: https://www.hzdr.de/publications/Publ-34898
Publ.-Id: 34898


Minor Actinides Can Replace Essential Lanthanides in Bacterial Life

Singer, H.; Steudtner, R.; Klein, A. S.; Rulofs, C.; Zeymer, C.; Drobot, B.; Pol, A.; Martinez-Gomez, C.; Daumann, L. J.

Certain f-block elements—the lanthanides—have biological relevance in the context of methylotrophic bacteria. The respective strains incorporate these 4 f elements into the active site of one of their key metabolic enzymes, a lanthanide-dependent methanol dehydrogenase. In this study, we investigated whether actinides, the radioactive 5 f elements, can replace the essential 4 f elements in lanthanide-dependent bacterial metabolism. Growth studies with Methylacidiphilum fumariolicum SolV and the Methylobacterium extorquens AM1 ΔmxaF mutant demonstrate that americium and curium support growth in the absence of lanthanides. Moreover, strain SolV favors these actinides over late lanthanides when presented with a mixture of equal amounts of lanthanides together with americium and curium. Our combined in vivo and in vitro results establish that methylotrophic bacteria can utilize actinides instead of lanthanides to sustain their one-carbon metabolism if they possess the correct size and a +III oxidation state.

Keywords: Actinides; Lanthanides; Lanthanide-dependent bacteria; Methanol dehydrogenases; Lanthanide-binding proteins; Methane

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Permalink: https://www.hzdr.de/publications/Publ-34897
Publ.-Id: 34897


Evolution of Single-Level-Model parameters in the Mechanically controllable Break Junctions

Kilibarda, F.; Günther, F.; Kelling, J.; Strobel, A.; Zahn, P.; Juckeland, G.; Kurt, G.; Elke, S.; Gemming, S.; Erbe, A.

The electrical properties of single molecules can be investigated using atomically sharp metallic electrodes in mechanically controllable break junctions (MCBJs). The current-voltage (IV) characteristics of single molecules in such junctions are affected by the binding positions of the end groups on the tip-facets and tip-tip separation. In this poster, we present MCBJ experiments on N,N’-Bis(5-ethynylbenzenethiol-salicylidene)ethylenediamine (Salen). We discuss the evolution of the single level model (SLM) parameters namely, a) the energetic level (epsilon) of the dominant conducting channel and b) the coupling (Gamma) of the dominant conducting channel to the metallic electrodes. The SLM-parameters were evaluated for IV-curves recorded during opening measurements and fitted to the single level model. We explain the recurring peak-like features/protusions in the experimentally measured evolution of Gamma with increasing tip-tip separation, which we relate not only to the deformation of the molecule but also to the sliding of the anchor group above the electrode surface. We propose a novel, high-throughput approach to model the evolution of the SLM-parameters and perform transport calculations using the self-consistent charge scheme of the density-functional-based tight binding (SCC-DFTB) approach and the Green’s function formalism. Thereby, we consider many thermodynamically relevant configurations and assess the evolution of SLM-parameters using the SLM-curve fitting of the zero-bias transmission. The SLM-parameters are averaged using statistical weights obtained from a Metropolis simulation considering up to 200 000 configurations for selected tip-tip separations. The behavior of the averaged quantities with respect to the tip-tip separation reflects the experimentally observed evolution of the SLM-parameters astonishingly well.

Keywords: high-throughput approach; Mechanically controllable break junctions; single level model; Metropolis simulation; Evolution of Single-Level-Model parameters

  • Open Access Logo Poster (Online presentation)
    YOUNG RESEARCHER’S WORKSHOP ON MACHINE LEARNING FOR MATERIALS, 09.-13.05.2022, Trieste, Italy

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Permalink: https://www.hzdr.de/publications/Publ-34896
Publ.-Id: 34896


Pbx(OH)y cluster formation in STI framework-type zeolites: anomalous thermal behaviour and increased thermal stability

Cametti, G.; Roos, D. P.; Churakov, S. V.; Prieur, D.; Scheinost, A. C.

The structural modifications occurring in zeolites upon heating are of interest because of technological and industrial applications. In this study, we report the anomalous behaviour of a Pb-exchanged zeolite (Pb13.4(OH)10Al17.4Si54.6O144 ∙38H2O) with STI framework type. For the first time, we observed a switch forom negative to positive thermal expansion during continuous heating. The dehydration was tracked in situ from 25 to 450 °C by single crystal X-ray diffraction, infrared, and X-ray absorption spectroscopy. Furthermore, toTo assist interpretation of the experimental results, molecular dynamics simulations were performed on a series of different theoretical models. Initially, Pb-STI unit-cell volume contracts (ΔV = -3.5%) from 25 to 100°C. This is in line with the trend observed in STI zeolites. Surprisingly, at 125°C, the framework expanded (ΔV = +2%), adopting a configuration, which resembles that of the room temperature structure. Upon heating, the structure loses H2O but no de-hydroxylation occurred. This behaviour is explained via the formation of Pbx(OH)x (x= 2,4) clusters, which prevent the shrinking of the channels, rupture of the tetrahedral bonds and occlusion of the pores. This zeolite has therefore an increased thermal stability with respect to other STI metal-exchanged zeolites, with important consequences foron its applications.

Keywords: Zeolite; ROBL; negative thermal expansion

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Permalink: https://www.hzdr.de/publications/Publ-34893
Publ.-Id: 34893


Curvilinear Micromagnetism: from fundamentals to applications

Sheka, D.; Makarov, D.

This book presents a timely and fundamental overview of magnetism in curved geometries, highlighting numerous peculiarities emerging from geometrically curved magnetic objects such as curves wires, shells, as well as complex three-dimensional structures. Extending planar two-dimensional structures into the three-dimensional space has become a general trend in multiple disciplines across electronics, photonics, plasmonics and magnetics. This approach provides the means to modify conventional and even launch novel functionalities by tailoring the local curvature of an object. The book covers the theory of curvilinear micromagnetism as well as experimental studies of curved magnets including both fabrication and characterization. With its coverage of theoretical and fundamental aspects, together with exploration of numerous applications across magnonics, bio-engineering, soft robotics and shapeable magnetoelectronics, this edited collection is ideal for all scientists in academia and industry seeking an overview and wishing to keep abreast of advances in the novel field of curvilinear micromagnetism. It provides easy but comprehensive access to the field for newcomers, and can be used for graduate-level courses on this subject.

Keywords: curvature effects in magnetism; curvilinear magnetism; printed electronics; magnetic field sensors; flexible magnetoelectronics; soft magnetic robots

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Permalink: https://www.hzdr.de/publications/Publ-34892
Publ.-Id: 34892


Curvilinear Magnetic Shells

Sheka, D.; Kravchuk, V.; Peddis, D.; Varvaro, G.; Krupinski, M.; Albrecht, M.; Erb, D.; Facsko, S.; Makarov, D.

In this chapter, we extend the discussion of curvature effects in magnetism towards the description of
geometrically curved magnetic thin shells. A self-consistent micromagnetic framework of curvilinear
magnetism describes the impact of curvature–induced effects, driven by both local and nonlocal
interactions, on the statics and dynamics of magnetic textures in extended curved thin shells. In particular,
we focus on the effects in magnetic thin films with in-plane and out-of-plane easy axis of magnetization on
spherical, cone-, bump-, and indentation-like objects. The special interest will be addressed to skyrmions in
curved magnetic films. Statics of skyrmions as well as their magnetization dynamics will be considered.
We provide an overview of relevant experimental methods, which allow fabricating these geometrically
curved extended thin films including nanosphere lithography, ion beam induced surface patterning and also
chemical synthesis approaches to realize metal and oxide hollow nanostructures with a tunable
morphology. We anticipate that the strong theoretical background on the fundamental understanding of the
curvature effects in geometrically curved magnetic shells and the availability of the fabrication methods to
produce these architectures will stimulate experimental activities targeting the validation of the exciting
theoretical predictions including curvature–induced skyrmions, pinning of chiral domain walls on local
bends and exploring novel nonlocal chiral symmetry breaking effects.

Keywords: curvature effects in magnetism; curvilinear magnetism; curved magnetic thin films; magnetochirality

Related publications

  • Book chapter
    Denys Makarov and Denis Sheka: Curvilinear Micromagnetism: from fundamentals to applications, Switzerland: Springer Nature, 2022, 978-3-031-09085-1
    DOI: 10.1007/978-3-031-09086-8_3

Permalink: https://www.hzdr.de/publications/Publ-34891
Publ.-Id: 34891


Geometrically Curved Magnetic Field Sensors for Interactive Electronics

Canon Bermudez, G. S.; Makarov, D.

The concept of curvilinear magnetism can be applied to a wide range of materials and targets the
applications where the interplay of geometry, shape, and magnetic texture arises. A clear advantage of
these deformable magnetic materials is that they can be used for applications that demand flexibility or
stretchability, something that conventionally rigid ferromagnets cannot provide. This advantage can be
readily exploited in the field of flexible electronics, which aims to create electronic circuits and devices
that can be folded or bent upon usage. The firm link between the fundamentals and applications of curved
magnetic thin films is given by the fact that magnetic domain walls can be pinned at bends.
This fundamental discovery has deep consequences for magnetic field sensors based on geometrically
curved magnetic thin films. Indeed, curvature of the structure results in an additional pinning mechanism
for domain walls, which can lead to the enhancement of the coercive field and hence lower the sensitivity
of magnetic field sensors. These considerations came up very recently and its consequences are still to be
explored and confirmed experimentally. Here, we will discuss primary the current advances in the
application of flexible magnetic field sensors based on geometrically curved magnetic thin films and
multilayers. Based on this technology, we present and foresee a wide range of applications in the fields of
eMobility, health, and interactive electronics. The latter is the main focus of this chapter, in particular due
to the added value of flexible magnetoelectronics to the fields of human-machine interfaces and virtual or
augmented reality.

Keywords: flexible magnetic field sensors; flexible electronics; interactive electronics; human-machine interfaces

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Permalink: https://www.hzdr.de/publications/Publ-34890
Publ.-Id: 34890


Actions for increased yields and easier maintenance at the Tracerlab FXC-pro system in the synthesis of L-[11C]methionine

Mäding, P.; Zessin, J.; Kreller, M.; Kopka, K.; Knieß, T.

L-[11C]Methionine ([11C]Met) is frequently used for the diagnosis of tumours located in brain, head and neck or for tumours induced by the multiple myeloma. The radio synthesis of [11C]Met commonly starts with [11C]CO2 with subsequent transformation to [11C]CH4 followed by transfer into [11C]CH3I which is used for final labelling of the precursor L-homocystein thiolactone hydrochloride (HCTL). [1,2] By performing these steps with the TRACERLab FXC-pro System (GE HC), however, we observed inconstant radiochemical yields and high maintenance efforts especially of the absorber material used within the gas phase iodination. Accordingly, we have searched for optimization of this radio synthesis procedure.

  • Poster
    20th European Symposium on Radiopharmacy and Radiopharmaceuticals, 24.-27.11.2022, Verona, Italien
  • Open Access Logo Contribution to proceedings
    Abstracts from the 20th European symposium on radiopharmacy and radiopharmaceuticals, 24.-27.11.2022, Verona, Italien
    EJNMMI Radiopharmacy and Chemistry
    DOI: 10.1186/s41181-023-00193-4

Permalink: https://www.hzdr.de/publications/Publ-34888
Publ.-Id: 34888


Free-electron lasers: past, present, and future challenges

Helm, M.

Free-electron lasers: past, present, and future challenges

Keywords: free electron laser

  • Invited lecture (Conferences) (Online presentation)
    International Conference on Free Electrons Laser Applications in Infrared and THz Studies of New States of Matter, 05.-08.07.2022, Warsaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-34887
Publ.-Id: 34887


Review of recent progress on advanced photocathodes for SC RF guns

Xiang, R.; Schaber, J.

As well known, the quality of the photocathodes is essential for the stability and the reliability of photo injector operation. Especially for the superconducting ratio frequency photo injectors (SRF guns), the photocathode represents one of the most critical parts. Benefit from the fast de-veloping photocathode technology in last years, several SRF guns were successfully operated or tested for the beam generation at kHz - MHz repetition rate. In this paper, we will review the achievements as well as the open questions in the applications of the photocathodes for SRF gun operation. Furthermore, we will discuss the possible improvement from cathodes side for the future CW electron sources.

Keywords: photocathode; SRF gun; superconducting RF photo injector; quantum efficiency

Permalink: https://www.hzdr.de/publications/Publ-34886
Publ.-Id: 34886


Interface effect of Fe and Fe2O3 on the distributions of ion induced defects

Kim, H.; Chancey, M. R.; Chung, T.; Brackenbury, I.; Liedke, M. O.; Butterling, M.; Hirschmann, E.; Wagner, A.; Baldwin, J. K.; Derby, B. K.; Li, N.; Yano, K. H.; Edwards, D. J.; Wang, Y.; Selim, F. A.

The stability of structural materials in extreme nuclear reactor environments—with high temperature, high radiation and corrosive media—directly affects the lifespan of the reactor. In such extreme environments, an oxide layer on the metal surface acts as a passive layer protecting the metal underneath from corrosion. To predict the irradiation effect on the metal layer in these metal/oxide bilayers, nondestructive depth-resolved positron annihilation lifetime spectroscopy (PALS) and complementary transmission electron microscopy (TEM) were used to investigate small-scale defects created by ion irradiation in an epitaxially grown (100) Fe film capped with a 50 nm Fe2O3 oxide layer. In this study, the evolution of induced vacancies was monitored, from individual vacancy formation at low doses—10^-5 dpa—to larger vacancy cluster formation at increasing doses, showing the sensitivity of positron annihilation spectroscopy techniques. Furthermore, PALS measurements reveal how the presence of a metal-oxide interface modifies the distribution of point defects induced by irradiation. TEM measurements show that irradiation induced dislocations at the interface is the mechanism behind the redistribution of point defects causing their accumulation close to the interface. This work demonstrates that the passive oxide layers formed during corrosion impact the distribution and accumulation of radiation induced defects in the metal underneath, and emphasizes that the synergistic impact of radiation and corrosion will differ from their individual impacts.

Keywords: positron annihilation spectroscopy; Fe; Fe2O3; defects; ion irradiation; interface

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Permalink: https://www.hzdr.de/publications/Publ-34885
Publ.-Id: 34885


Exploring the Reduction Mechanism of ⁹⁹Tc(VII) in NaClO₄: A Spectro-Electrochimical Approach

Rodriguez Hernandez, D. M.; Mayordomo, N.; Parra-Puerto, A.; Schild, D.; Brendler, V.; Stumpf, T.; Müller, K.

Technetium (Tc) is an environmentally relevant radioactive contaminant whose migration is limited when Tc(VII) is reduced to Tc(IV). However, its reaction mechanisms are not well understood yet. We have combined electrochemistry, spectroscopy, and microscopy (cyclic voltammetry, rotating disk electrode, X-ray photoelectron spectroscopy, and Raman and scanning electron microscopy) to study Tc(VII) reduction in non-complexing media: 0.5 mM KTcO₄ in 2 M NaClO₄ in the pH from 2.0 to 10.0. At pH 2.0, Tc(VII) first gains 2.3 ± 0.3 electrons, following Tc(V) rapidly receives 1.3 ± 0.3 electrons yielding Tc(IV). At pH 4.0−10.0, Tc(IV) is directly obtained by transfer of 3.2 ± 0.3 electrons. The reduction of Tc(VII) produced always a black solid identified as Tc(IV) by Raman and XPS. Our results
narrow a significant gap in the fundamental knowledge of Tc aqueous chemistry and are important to understand Tc speciation.
They provide basic steps on the way from non-complexing to complex media.

Keywords: Technetium; Raman spectroscopy; X-ray photoelectron spectroscopy; Non-complexing media

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Permalink: https://www.hzdr.de/publications/Publ-34883
Publ.-Id: 34883


Complexation of Eu(III) and Cm(III) by EGTA related aminopolycarboxylic acids

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

For purposes of chelation therapy and radiation protection, aminopolycarboxylic acids like ethylenediaminetetraacetic acid (EDTA) or diethylenetriaminepentaacetic acid (DTPA) are clinical approved decorporation agents against lanthanides (Ln) and actinides (An). This well known group of chelating agents shows promising results in complexation of Ln(III)/An(III). For EDTA and DTPA related compound ethylene glycol-bis(β-aminoethyl ether)-N,N,N’,N’-tetraacetic acid (EGTA), complexes with trivalent europium (Eu) have been characterized by NMR spectroscopy and x-ray diffraction. In these complexes, EGTA acts as an octadentate ligand.[1][2] In this work the knowledge on the Eu-EGTA-system is extended by time-resolved laser-induced fluorescence spectroscopy (TRLFS), electrospray ionization mass spectrometry (ESI-MS) and isothermal titration calorimetry (ITC). These speciation studies on Eu(III) show promising results for EGTA as complexing agent.
To expand this ligand group, EGTA related ligands are synthesized. With these compounds, the complexation behaviour towards Eu(III) and curium(III) are determined and comprehensively characterised from both the ligands and metals perspective with TRLFS, NMR spectroscopy, single crystal x-ray diffraction and fourier-transform infrared spectroscopy. The overall goal is a better understanding between ligand design and affinity to trivalent lanthanides and actinides. Hence, in the future these ligands may contribute to chelation therapy as decorporation agents.
This work is funded by the German Federal Ministry of Education and Research (BMBF) under grant number 02NUK057A and part of the joint project RADEKOR.

[1]. S. Aime, A. Barge, A. Borel, M. Botta, S. Chemerisov, A. E. Merbach, U. Müller, D. Pubanz, Inorg. Chem. 1997, 36, 5104.
[2]. R. Xu, D. Li, J. Wang, Y. X. Kong, B. X. Wang, Y. M. Kong, T. T. Fan, B. Liu, Russ. J. Coord. Chem. 2010, 36, 810.

  • Poster
    Actinides revisited 2022, 21.-23.09.2022, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34882
Publ.-Id: 34882


Assessment of gene expressions from squamous cell carcinoma of the head and neck to predict radiochemotherapy-related xerostomia and dysphagia

Yahya, N.; Linge, A.; Leger, K.; Maile, T.; Kemper, M.; Haim, D.; Jöhrens, K.; Troost, E. G. C.; Krause, M.; Löck, S.

Purpose: We tested the hypothesis that gene expressions from biopsies of locally advanced head and neck squamous cell carcinoma (HNSCC) patients can supplement dose-volume parameters to predict dysphagia and xerostomia following primary radiochemotherapy (RCTx).
Material and methods: A panel of 178 genes previously related to radiochemosensitivity of HNSCC was considered for nanoString analysis based on tumour biopsies of 90 patients with locally advanced HNSCC treated by primary RCTx. Dose-volume parameters were extracted from the parotid, subman-
dibular glands, oral cavity, larynx, buccal mucosa, and lips. Normal tissue complication probability (NTCP) models were developed for acute, late, and for the improvement of xerostomia grade ≥2 and dysphagia grade ≥3 using a cross-validation-based least absolute shrinkage and selection operator (LASSO) approach combined with stepwise logistic regression for feature selection. The final signatures were included in a logistic regression model with optimism correction. Performance was assessed by the area under the receiver operating characteristic curve (AUC).
Results: NTCP models for acute and late xerostomia and the improvement of dysphagia resulted in optimism-corrected AUC values of 0.84, 0.76, and 0.70, respectively. The minimum dose to the contra-lateral parotid was selected for both acute and late xerostomia and the minimum dose to the larynx was selected for dysphagia improvement. For the xerostomia endpoints, the following gene expressions were selected: RPA2 (cellular response to DNA damage), TCF3 (salivary gland cells development), GBE1 (glycogen storage and regulation), and MAPK3 (regulation of cellular processes). No gene expression features were selected for the prediction of dysphagia.
Conclusion: This hypothesis-generating study showed the potential of improving NTCP models using gene expression data for HNSCC patients. The presented models require independent validation before potential application in clinical practice.

Keywords: gene expressions; head and neck cancer; xerostomia; dysphagia; radiotherapy

Permalink: https://www.hzdr.de/publications/Publ-34881
Publ.-Id: 34881


Data publication: Tailoring pulsed laser deposition fabricated copper oxide film by controlling plasma parameters

Irimiciuc, S. A.; Chertopalov, S.; Volfová, L.; Hruska, P.; Cizek, J.; Vondracek, M.; Novotny, M.; Butterling, M.; Liedke, M. O.; Wagner, A.

Positron annihilation lifetime spectroscopy data from beamtime at ELBE

Keywords: pulsed laser deposition; copper oxide; defects; in situ plasma monitoring

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Permalink: https://www.hzdr.de/publications/Publ-34880
Publ.-Id: 34880


Tailoring pulsed laser deposition fabricated copper oxide film by controlling plasma parameters

Volfová, L.; Irimiciuc, S. A.; Chertopalov, S.; Hruska, P.; Cizek, J.; Vondracek, M.; Novotny, M.; Butterling, M.; Liedke, M. O.; Wagner, A.; Lancok, J.

Various copper oxide stoichiometries have been grown by Pulsed Laser Deposition (PLD) on MgO (100). The role of oxygen pressure on the structural and physical properties of the films was investigated in the 1·10 –5 Pa – 1 Pa range. Positron annihilation spectroscopy revealed positrons trapped at vacancies and large vacancy clusters with lifetimes ranging from 400 ps to 500 ps. Different stoichiometries were found to be dominated by characteristic vacancies. Single copper vacancies V Cu are found for CuO phase with good indication for p-type applications while for the Cu 2 O complexes of copper vacancies coupled with oxygen vacancies (V Cu + V O and V Cu + 2V O ) are seen. Particular O 2 atmosphere conditions induce a mixture of copper oxide phases with the CuO crystals growing on top of Cu 2 O films. The deposition process was monitored with in situ diagnostic techniques based on optical emission spectroscopy and Langmuir probe method. The kinetics of the plasma during the deposition process are well correlated with the properties of the deposited films.
The monitoring tools define clear energetic threshold for the formation of CuO or Cu 2 O phases.

Keywords: pulsed laser deposition; copper oxide; defects; in situ plasma monitoring

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Permalink: https://www.hzdr.de/publications/Publ-34879
Publ.-Id: 34879


Characterization of the binding behavior of specific cobalt- and nickel ion-binding peptides identified by phage surface display

Matys, S.; Morawietz, L.-M.; Lederer, F.; Pollmann, K.

In recent years, the application focus of phage surface display (PSD) technology has been extended to the identification of metal ion-selective peptides. In previous studies, two phage clones - a nickel-binding one with the peptide motif CNAKHHPRCGGG and a co-balt-binding one with the peptide motif CTQMLGQLCGGG - were isolated and their binding ability to metal-loaded NTA agarose beads was investigated. Here, the free cyclic peptides are characterized by UV/VIS spectroscopy and with respect to their binding capacity for the respective target ion as well as in crossover experiments for the other ion by isothermal titration calorimetry (ITC) in different buffer systems. This revealed differences in selectivity and affinity. While the cobalt-specific peptide is very sensitive to different buffers, but has a 20-fold higher affinity for cobalt and nickel under suitable conditions, the nickel-specific peptide binds more moderately and robustly in different buffers, but selectively only nickel.

Keywords: phage surface display; biopanning; metal binding peptides; nickel; cobalt; isothermal titration calorimetry

Permalink: https://www.hzdr.de/publications/Publ-34878
Publ.-Id: 34878


Visualisation of torsional modes with contactless inductive flow tomography

Molenaar, P.; Wondrak, T.; Jacobs, R. T.; Sonntag, S.; Krauthäuser, H. G.

The contactless inductive flow tomography is a procedure that enables the reconstruction of the global three-dimensional flow structure of an electrically conducting fluid by measuring the flow-induced perturbation of an applied static magnetic field and by subsequently solving the associated linear inverse problem. The method enables the visualisation of the dynamics of a large-scale circulation in the modified Rayleigh-Bénard experiment.

Keywords: flow measurement; ontactless inductive flow tomography

  • Lecture (Conference)
    20th International IGTE Symposium 2022 on Computational Methods in Electromagnetics and Multiphysics, 18.-21.09.2023, Graz, Österreich

Permalink: https://www.hzdr.de/publications/Publ-34877
Publ.-Id: 34877


A Novel 2-Metagene Signature to Identify High-Risk HNSCC Patients amongst Those Who Are Clinically at Intermediate Risk and Are Treated with PORT

Patil, S. G.; Linge, A.; Hiepe, H.; Grosser, M.; Lohaus, F.; Gudziol, V.; Kemper, M.; Nowak, A.; Haim, D.; Tinhofer, I.; Budach, V.; Guberina, M.; Stuschke, M.; Balermpas, P.; Grün, J. V. D.; Schäfer, H.; Grosu, A.-L.; Abdollahi, A.; Debus, J.; Ganswindt, U.; Belka, C.; Pigorsch, S.; Combs, S. E.; Boeke, S.; Zips, D.; Jöhrens, K.; Baretton, G. B.; Baumann, M.; Krause, M.; Löck, S.

Abstract: (1) Background: Patients with locally advanced head and neck squamous cell carcinoma (HNSCC) who are at biologically high risk for the development of loco-regional recurrences af-ter postoperative radiotherapy (PORT) but at intermediate risk according to clinical risk factors may benefit from additional concurrent chemotherapy. In this matched-pair study, we aimed to identify a corresponding predictive gene signature. (2) Methods: Gene expression analysis was performed on a multicentre retrospective cohort of 221 patients that were treated with postoper-ative radiochemotherapy (PORT-C) and 283 patients that were treated with PORT alone. Propen-sity score analysis was used to identify matched patient pairs from both cohorts. From differen-tial gene expression analysis and Cox regression, a predictive gene signature was identified. (3) Results: 108 patient matched patient pairs were selected. We identified a 2-metagene signature that stratified patients into risk groups in both cohorts. The comparison of the high-risk patients between the two types of treatment showed higher LRC after treatment with PORT-C (p<0.001), which was confirmed by a significant interaction term in Cox regression (p=0.027), i.e. the 2-metagene signature was indicative for the type of treatment. (4) Conclusion: We have identi-fied a novel gene signature that may be helpful to identify patients with high-risk HNSCC amongst those at intermediate clinical risk treated with PORT, who may benefit from additional concurrent chemotherapy.

Keywords: head and neck squamous cell carcinoma; gene signature; postoperative radiotherapy; postoperative radiochemotherapy; propensity score matching

Permalink: https://www.hzdr.de/publications/Publ-34875
Publ.-Id: 34875


Investigation of complex electrical properties of concrete: A numerical model analysis

Nurjahan, T.; Schleicher, E.; de Assis Dias, F.; Hampel, U.

Electrical impedance spectroscopy (EIS) is a powerful technique and observed to be more sensitive to complex composite and hydration which provides the estimated solution to our questions. Therefore, this letter deals with some of the preliminary results of the research. It reflects upon studying the complex electrical properties of the cementitious material through the numerical analysis over the range of 1 Hz to 10 MHz frequencies for dry and moist concrete samples.

Keywords: electrical impedance spectroscopy; complex electrical properties; moisture; Nyquist plots

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Permalink: https://www.hzdr.de/publications/Publ-34872
Publ.-Id: 34872


Controllable electrostatic manipulation of structure building blocks in noble metal aerogels

Wei, W.; Hübner, R.; Georgi, M.; Wang, C.; Wu, X.; Eychmüller, A.

The important role of structure homogeneity in three-dimensional network nanostructures serving as noble metal aerogels (NMAs) has attracted extensive attention in the field of electrochemistry in the last two decades, whereas a comprehensive study of tailoring skeleton units and element distributions in NMAs is still lacking. Herein, a new modulation strategy to easily prepare multiscale NMAs with tunable composition is developed by utilizing the electrostatic interaction between oppositely charged colloidal metal nanoparticles. The modulation rule of the chemical distribution in bimetallic aerogels leads to the construction of the as-tailored double skeleton aerogels for the first time. Considering their specific structures, the intrinsic and exceptional catalytic and electrocatalytic performances of NMAs were investigated. This study optimizes the structure homogeneity of noble metal aerogels by investigating nanoparticle–ligand interactions and provides further proof of their exceptional electrocatalytic
capabilities.

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Permalink: https://www.hzdr.de/publications/Publ-34871
Publ.-Id: 34871


Homogenization and short-range chemical ordering of Co-Pt alloys driven by the grain boundary migration mechanism

Pedan, R.; Makushko, P.; Dubikovskyi, O.; Bodnaruk, A.; Burmak, A.; Sidorenko, S.; Voloshko, S.; Kalita, V.; Hübner, R.; Makarov, D.; Vladymyrskyi, I.

Binary magnetic alloys like Co-Pt are relevant for applications as components of magnetic exchange coupled composites. Numerous approaches exist to tune the coercive field of Co-Pt alloys primarily relying on hightemperature processing aiming to realize chemically long-range ordered phases. The peculiarity of Co-Pt is that large coercive field and magnetic anisotropy can be achieved even in chemically disordered alloys relying on short-range order. Here, we study alloying of Co-Pt from bilayers of Pt(14 nm) Co(13 nm) at temperatures up to 550 degС, where bulk diffusion processes are suppressed and the dominant diffusion mechanism is grain boundary migration. We demonstrate that grain boundary diffusion mechanism can lead to the realization of a homogeneous yet chemically disordered Co56Pt44 alloy at temperatures of 500 degС and higher. A pronounced increase of the coercive field for samples processed at temperatures higher than 400 degС is attributed to short-range ordering. With this work, we pinpoint the grain boundary diffusion as the mechanism responsible not only for the homogenization of binary alloy films but also as a driving force for the realization of short-range order in Co-Pt. Our results motivate further research on grain boundary diffusion as a mechanism to realize chemically long-range ordered phases in Co-Pt alloys.

Keywords: grain boundary diffusion; magnetic thin films; short-range chemical order; Co-Pt alloy

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Permalink: https://www.hzdr.de/publications/Publ-34870
Publ.-Id: 34870


Pickering interfacial catalysts for asymmetric organocatalysis

Sun, Z.; Jurica, J.; Hübner, R.; Wu, C.

Proline-catalyzed aldol reactions have been developed as an important toolbox for the synthesis of valuable chiral intermediates, giving birth to asymmetric organocatalysis. Despite progress, their current applications are generally performed in highly polar solvents that are either difficult to remove or with low substrate/product solubility. In addition, prolines are often used as homogeneous organocatalysts in these solvents, thus, the recycling of catalyst for reuse is also challenging. To solve these problems, we develop a proline-based Pickering emulsion for asymmetric aldol reactions with high reactivity and selectivity. The emulsion was stabilized by proline-functionalized silica nanoparticles that are not only highly active in the presence of water but also easily recycled after the operation. Interestingly, their high stereoselectivity was not compromised after multiple reuse, i.e., >86 ee (enantiomeric excess) in the first and second use. With this demonstration, we prove the concept that efficient and selective aldol reactions are enabled by proline-based Pickering emulsions, which is a great and continuous contribution to the field of asymmetric organocatalysis.

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Permalink: https://www.hzdr.de/publications/Publ-34869
Publ.-Id: 34869


Artificially sporulated Escherichia coli cells as a robust cell factory for interfacial biocatalysis

Sun, Z.; Hübner, R.; Li, J.; Wu, C.

The natural bacterial spores have inspired the development of artificial spores, through coating cells with protective materials, for durable whole-cell catalysis. Despite attractiveness, artificial spores developed to date are generally limited to a few microorganisms with their natural endogenous enzymes, and they have never been explored as a generic platform for widespread synthesis. Here, we report a general approach to designing artificial spores based on Escherichia coli cells with recombinant enzymes. The artificial spores are simply prepared by coating cells with polydopamine, which can withstand UV radiation, heating and organic solvents. Additionally, the protective coating enables living cells to stabilize aqueous-organic emulsions for efficient interfacial biocatalysis ranging from single reactions to multienzyme cascades. Furthermore, the interfacial system can be easily expanded to chemoenzymatic synthesis by combining artificial spores with metal catalysts. Therefore, this artificial-spore-based platform technology is envisioned to lay the foundation for nextgeneration cell factory engineering.

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Permalink: https://www.hzdr.de/publications/Publ-34868
Publ.-Id: 34868


Importance of long-term follow up to address long-term effectiveness and toxicity of radiotherapy

Schneider, M.; Linge, A.; Krause, M.; Baumann, M.

Modern radiotherapy and advances in systemic treatments are
leading to higher tumour control rates and longer survival rates,
thereby the number of long-term survivors of malignant tumours
is increasing. Therefore, minimising late and very late side
effects including radiation-induced secondary malignancies is par-
ticularly important. Accurate quantification of such sequelae is
only possible through very long, optimistically lifelong follow-up
of patients and comprehensive cancer registers

Keywords: none

Permalink: https://www.hzdr.de/publications/Publ-34867
Publ.-Id: 34867


Plasticity within Aldehyde Dehydrogenase-Positive Cells Determines Prostate Cancer Radiosensitivity

Schwarz, F. M.; Schniewind, I.; Besso, M. J.; Lange, S.; Linge, A.; Patil, S. G.; Löck, S.; Klusa, D.; Dietrich, A.; Voss-Böhme, A.; Nowrouzi, A.; Krause, M.; Dubrovska, A.; Kurth, I.; Peitzsch, C.

Tumor heterogeneity and cellular plasticity are key determinants of tumor progression, metastatic spread, and therapy
response driven by the cancer stem cell (CSC) population. Within the current study, we analyzed irradiation-induced
plasticity within the aldehyde dehydrogenase (ALDH)-positive (ALDH+) population in prostate cancer. The radiosensitivity of
xenograft tumors derived from ALDH+ and ALDH-negative (ALDH-) cells was determined with local tumor control analyses
and demonstrated different dose-response profiles, time to relapse, and focal adhesion signaling. The transcriptional
heterogeneity was analyzed in pools of 10 DU145 and PC3 cells with multiplex gene expression analyses and illustrated a
higher degree of heterogeneity within the ALDH+ population that even increases upon irradiation in comparison with ALDH-
cells. Phenotypic conversion and clonal competition were analyzed with fluorescence protein-labeled cells to distinguish
cellular origins in competitive three-dimensional cultures and xenograft tumors. We found that the ALDH+ population
outcompetes ALDH- cells and drives tumor growth, in particular upon irradiation. The observed dynamics of the cellular state
compositions between ALDH+ and ALDH- cells in vivo before and after tumor irradiation was reproduced by a probabilistic
Markov compartment model that incorporates cellular plasticity, clonal competition, and phenotype-specific radiosensitivities.
Transcriptional analyses indicate that the cellular conversion from ALDH- into ALDH+ cells within xenograft tumors under
therapeutic pressure was partially mediated through induction of the transcriptional repressor SNAI2. In summary,
irradiation-induced cellular conversion events are present in xenograft tumors derived from prostate cancer cells and may be
responsible for radiotherapy failure. IMPLICATIONS: The increase of ALDH+ cells with stem-like features in prostate
xenograft tumors after local irradiation represents a putative cellular escape mechanism inducing tumor radioresistance.

Keywords: aldehyde dehydrogenase; genetics; human; male; prostate tumor; radiation tolerance; tumor recurrence; aldehyde dehydrogenase; neplasm recurrence; local

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Permalink: https://www.hzdr.de/publications/Publ-34866
Publ.-Id: 34866


Unveiling the Zero-Phonon Line of the Boron Vacancy Center by Cavity-Enhanced Emission

Qian, C.; Villafañe, V.; Schalk, M.; Astakhov, G.; Kentsch, U.; Helm, M.; Soubelet, P.; Wilson, N. P.; Rizzato, R.; Mohr, S.; Holleitner, A. W.; Bucher, D. B.; Stier, A. V.; Finley, J. J.

Negatively charged boron vacancies (VB−) in hexagonal boron nitride (hBN) exhibit a broad emission spectrum
due to strong electron−phonon coupling and Jahn−Teller mixing of electronic states. As such, the direct measurement of the zero-
phonon line (ZPL) of VB− has remained elusive. Here, we measure the room-temperature ZPL wavelength to be 773 ± 2 nm by
coupling the hBN layer to the high-Q nanobeam cavity. As the wavelength of cavity mode is tuned, we observe a pronounced
intensity resonance, indicating the coupling to VB−. Our observations are consistent with the spatial redistribution of VB−
emission. Spatially resolved measurements show a clear Purcell effect maximum at the midpoint of the nanobeam, in accord with
the optical field distribution of the cavity mode. Our results are in good agreement with theoretical calculations, opening the way to using VB− as cavity spin−photon interfaces.

Keywords: 2D materials; Spins; hBN defect emitter; cavity-emitter coupling

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Permalink: https://www.hzdr.de/publications/Publ-34865
Publ.-Id: 34865


1-(4-Fluorobenzoyl)-9H-carbazole

Laube, M.; König, J.; Köckerling, M.; Knieß, T.

1-(4-Fluorobenzoyl)-9H-carbazole (1) was synthesized starting from 9H carbazole and 4-fluorobenzonitrile by Friedel-Crafts acylation using boron trichloride to direct the substitu-tion in 1-position. Single X-ray crystal structure analysis unambiguously revealed the molecular structure of 1.

Keywords: Carbazole; Friedel-Crafts acylation; Boron trichloride; Structure determination

Permalink: https://www.hzdr.de/publications/Publ-34863
Publ.-Id: 34863


Evaluation of prognostic factors after primary chemoradiotherapy of anal cancer: A multicenter study of the German Cancer Consortium- Radiation Oncology Group (DKTK-ROG)

Martin, D.; Schreckenbach, T.; Ziegler, P.; Filmann, N.; Kalinauskaite, G.; Tinhofer, I.; Budach, V.; Gani, C.; Zips, D.; Schimek-Jasch, T.; Schäfer, H.; Grosu, A. L.; Thomas, E.; Krause, M.; Dapper, H.; Combs, S.; Hoffmann, C.; Stuschke, M.; Walter, F.; Belka, C.; Kurth, I.; Hadiwikarta, W. W.; Baumann, M.; Rödel, C.; Fokas, E.

Background and purpose: Prognosis after chemoradiotherapy (CRT) for anal squamous cell carcinoma
(ASCC) shows marked differences among patients according to TNM subgroups, however individualized
risk assessment tools to better stratify patients for treatment (de-) escalation or intensified follow-up are
lacking in ASCC.
Materials and methods: Patients’ data from eight sites of the German Cancer Consortium - Radiation
Oncology Group (DKTK-ROG), comprising a total of 605 patients with ASCC, treated with standard defini-
tive CRT with 5-FU/Mitomycin C or Capecitabine/Mitomycin C between 2004–2018, were used to evalu-
ate prognostic factors based on Cox regression models for disease-free survival (DFS). Evaluated variables
included age, gender, Karnofsky performance score (KPS), HIV-status, T-category, lymph node status and
laboratory parameters. Multivariate cox models were separately constructed for the whole cohort and
the subset of patients with early-stage (cT1-2 N0M0) tumors.
Results: After a median follow-up of 46 months, 3-year DFS for patients with early-stage ASCC was 84.9%,
and 67.1% for patients with locally-advanced disease (HR 2.4, p < 0.001). T-category (HR vs. T1: T2 2.02;
T3 2.11; T4 3.03), N-category (HR versus N0: 1.8 for N1-3), age (HR 1.02 per year), and KPS (HR 0.8 per
step) were significant predictors for DFS in multivariate analysis in the entire cohort. The model per-
formed with a C-index of 0.68. In cT1-2N0 patients, T-category (HR 2.14), HIV status (HR 2.57), age
(1.026 per year), KPS (HR 0.7 per step) and elevated platelets (HR 1.3 per 100/nl) were associated with
worse DFS (C-index of 0.7).
Conclusion: Classical clinicopathologic parameters like T-category, N-category, age and KPS remain to be
significant prognostic factors for DFS in patients treated with contemporary CRT for ASCC. HIV and plate-
lets were significantly associated with worse DFS in patients with early stage ASCC.

Keywords: Anal cancer; Chemoradiotherapy; Prognostic factors; Cox regression

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Permalink: https://www.hzdr.de/publications/Publ-34862
Publ.-Id: 34862


Influence of the First Wave of the COVID-19 Pandemic on Cancer Care in a German Comprehensive Cancer Center

Kirchberg, J.; Rentsch, A.; Klimova, A.; Vovk, V.; Hempel, S.; Folprecht, G.; Krause, M.; Plodeck, V.; Welsch, T.; Weitz, J.; Fritzmann, J.

Introduction: During the first wave of the COVID-19 pandemic in 2020, the German
government implemented legal restrictions to avoid the overloading of intensive care units
by patients with COVID-19. The influence of these effects on diagnosis and treatment of
cancer in Germany is largely unknown.
Methods: To evaluate the effect of the first wave of the COVID-19 pandemic on tumor
board presentations in a high-volume tertiary referral center (the German Comprehensive
Cancer Center NCT/UCC Dresden), we compared the number of presentations of
gastrointestinal tumors stratified by tumor entity, tumor stage, and treatment intention
during the pandemic to the respective data from previous years.
Results: The number of presentations decreased by 3.2% (95% CI −8.8, 2.7) during the
COVID year 2020 compared with the pre-COVID year 2019. During the first shutdown,
March–May 2020, the total number of presentations was 9.4% (−18.7, 1) less than during
March–May 2019. This decrease was significant for curable cases of esophageal cancer
[N =37, 25.5% (−41.8, −4.4)] and colon cancer [N =36, 17.5% (−32.6, 1.1)] as well as
for all cases of biliary tract cancer [N =26, 50% (−69.9, −15)] during the first shutdown
from March 2020 to May 2020.
Conclusion: The impact of the COVID-19 pandemic on the presentation of oncological
patients in a CCC in Germany was considerable and should be taken into account when
making decisions regarding future pandemics.

Keywords: COVID-19 pandemic; cancer care; German health care; comprehensive cancer center

Permalink: https://www.hzdr.de/publications/Publ-34861
Publ.-Id: 34861


CRISPR-Cas9 Screen Identifies DYRK1A as a Target for Radiotherapy Sensitization in Pancreatic Cancer

Lan, B.; Zeng, S.; Zhang, S.; Ren, X.; Xing, Y.; Kutschick, I.; Pfeffer, S.; Frey, B.; Britzen-Laurent, N.; Grützmann, R.; Cordes, N.; Pilarsky, C.

Although radiation therapy has recently made great advances in cancer treatment, the
majority of patients diagnosed with pancreatic cancer (PC) cannot achieve satisfactory outcomes
due to intrinsic and acquired radioresistance. Identifying the molecular mechanisms that impair
the efficacy of radiotherapy and targeting these pathways are essential to improve the radiation
response of PC patients. Our goal is to identify sensitive targets for pancreatic cancer radiotherapy
(RT) using the kinome-wide CRISPR-Cas9 loss-of-function screen and enhance the therapeutic
effect through the development and application of targeted inhibitors combined with radiotherapy.
We transduced pancreatic cancer cells with a protein kinase library; 2D and 3D library cells were
irradiated daily with a single dose of up to 2 Gy for 4 weeks for a total of 40 Gy using an X-ray
generator. Sufficient DNA was collected for next-generation deep sequencing to identify candidate
genes. In this study, we identified several cell cycle checkpoint kinases and DNA damage related
kinases in 2D- and 3D-cultivated cells, including DYRK1A, whose loss of function sensitizes cells
to radiotherapy. Additionally, we demonstrated that the harmine-targeted suppression of DYRK1A
used in conjunction with radiotherapy increases DNA double-strand breaks (DSBs) and impairs
homologous repair (HR), resulting in more cancer cell death. Our results support the use of CRISPR-
Cas9 screening to identify new therapeutic targets, develop radiosensitizers, and provide novel
strategies for overcoming the tolerance of pancreatic cancer to radiotherapy.

Keywords: pancreatic cancer; CRISPR-Cas9; radiotherapy; radioresistance; DYRK1A; Harmine; DNA damage repair; DNA double-strand break

Permalink: https://www.hzdr.de/publications/Publ-34860
Publ.-Id: 34860


Patterns Of Practice for Adaptive and Real-Time Particle Therapy (POP-ART PT), part II: Plan adaptation for interfractional changes

Trnkova, P.; Zhang, Y.; Toshito, T.; Heijmen, B.; Richter, C.; Aznar, M.; Bolsi, A.; Daartz, J.; Knopf, A.; Bertholet, J.

Real-time respiratory motion management (RRMM, intra-fraction geometrical intervention) and Adaptive Particle Therapy (APT, inter-fraction adaptation of treatment plans) enable to account for anatomical variations and changes to optimize target coverage and organs-at-risk sparing. However, their current clinical implementation is unclear and expected to be highly heterogeneous. An institutional questionnaire, Patterns Of Practice for Adaptive and Real-Time Particle Therapy (POP-ART-PT), was distributed between 2021/01-06 to evaluate current clinical practice and wishes and barriers of the implementation. Here, we summarise the international survey results on APT for mitigation of interfractional anatomical changes from 70 particle therapy centers in 17 countries.

The response rate was 100% for Europe, 96% for Japan and 53% for USA. Of the 68 centers in operation, 84% (Figure1a) were APT users for at least one treatment site, with head and neck being the most common. APT was mostly performed offline (ad-hoc or per protocol) with only two users of online APT (plan library) and none using online daily replanning. Plan adaptation was in all cases motivated by both, target and OAR dose considerations (Figure1b). The most common imaging modality guiding APT was X-ray computed tomography. Sixty-eight percent of users plan to increase or change their APT technique. The greatest barriers to implementation were lack of integrated and efficient workflows and human resources (Figure2)

Offline APT has been widely implemented internationally, but online APT is still very rarely used. More research and development for integrated and efficient workflow is needed to facilitate the use of offline APT and enable online APT.

  • Lecture (Conference)
    PTCOG 60 - Jahreskonferenz der Particle Therapy Co-Operative Group, 28.06.-02.07.2022, Miami, USA

Permalink: https://www.hzdr.de/publications/Publ-34859
Publ.-Id: 34859


RawData - Liquid fraction investigations in a RPB (big printed zick-zack foam, multi point) using GammaCT

Bieberle, A.; Loll, R.; Pyka, T.; Schubert, M.
DataCollector: Bieberle, André; Researcher: Schubert, Markus; RelatedPerson: Zippe, Cornelius

For liquid fraction investigations in a rotating printed zick-zack foam (big) packed bed (RPB) angular-resolved time-averaged gamma-ray computed tomography (GammaCT) is applied. Liquid is injected by a multi point injector. This repository contains:

  • the raw data of the gamma-ray CT scanner,
  • the extracted projection-averaged profile data matrix and
  • the restructured angular-resolved time-averaged sinogram data.

Keywords: Rotating Packed Bed; Process Intensivation; Computed Tomography

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Permalink: https://www.hzdr.de/publications/Publ-34858
Publ.-Id: 34858


RawData - Liquid fraction investigations in a RPB (small printed zick-zack foam 2, multi point) using GammaCT

Bieberle, A.; Loll, R.; Pyka, T.; Schubert, M.
DataCollector: Bieberle, André; Researcher: Schubert, Markus; RelatedPerson: Zippe, Cornelius

For liquid fraction investigations in a rotating printed zick-zack foam (small) packed bed (RPB) angular-resolved time-averaged gamma-ray computed tomography (GammaCT) is applied. Liquid is injected by a multi point injector. This repository contains:

  • the raw data of the gamma-ray CT scanner,
  • the extracted projection-averaged profile data matrix and
  • the restructured angular-resolved time-averaged sinogram data.

Keywords: Rotating Packed Bed; Rotating Packed Bed; Computed Tomography

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Permalink: https://www.hzdr.de/publications/Publ-34857
Publ.-Id: 34857


RawData - Liquid fraction investigations in a RPB (small printed zick-zack foam, zero point) using GammaCT

Bieberle, A.; Loll, R.; Pyka, T.; Schubert, M.
DataCollector: Bieberle, André; Researcher: Schubert, Markus; RelatedPerson: Zippe, Corneliusv

For liquid fraction investigations in a rotating printed zick-zack foam (small) packed bed (RPB) angular-resolved time-averaged gamma-ray computed tomography (GammaCT) is applied. Liquid is injected by a zero point injector. This repository contains:

  • the raw data of the gamma-ray CT scanner,
  • the extracted projection-averaged profile data matrix and
  • the restructured angular-resolved time-averaged sinogram data.

Keywords: Rotating Packed Bed; Process Intensivation; Computed Tomography

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Permalink: https://www.hzdr.de/publications/Publ-34856
Publ.-Id: 34856


RawData - Liquid fraction investigations in a RPB (small printed zick-zack foam, multi point) using GammaCT

Bieberle, A.; Loll, R.; Pyka, T.; Schubert, M.
DataCollector: Bieberle, André; Researcher: Schubert, Markus; RelatedPerson: Zippe, Cornelius

For liquid fraction investigations in a rotating printed zick-zack foam (small) packed bed (RPB) angular-resolved time-averaged gamma-ray computed tomography (GammaCT) is applied. Liquid is injected by a multi point injector. This repository contains:

  • the raw data of the gamma-ray CT scanner,
  • the extracted projection-averaged profile data matrix and
  • the restructured angular-resolved time-averaged sinogram data.

Keywords: Rotating Packed Bed; Process Intensivation; Computed Tomography

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Permalink: https://www.hzdr.de/publications/Publ-34855
Publ.-Id: 34855


RawData - Liquid fraction investigations in a RPB (solid foam, single point) using GammaCT

Bieberle, A.; Loll, R.; Pyka, T.; Schubert, M.
DataCollector: Bieberle, André; Researcher: Schubert, Markus; RelatedPerson: Zippe, Cornelius

For liquid fraction investigations in a rotating solid foam packed bed (RPB) angular-resolved time-averaged gamma-ray computed tomography (GammaCT) is applied. Liquid is injected by a single point injector. This repository contains

  • the raw data of the gamma-ray CT scanner,
  • the extracted projection-averaged profile data matrix and
  • the restructured angular-resolved time-averaged sinogram data.

Keywords: Rotating Packed Bed; Process Intensivation; Computed Tomography

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Permalink: https://www.hzdr.de/publications/Publ-34854
Publ.-Id: 34854


RawData - Liquid fraction investigations in a RPB (solid foam, 12 baffles) using GammaCT

Bieberle, A.; Loll, R.; Pyka, T.; Schubert, M.
DataCollector: Bieberle, André; Researcher: Schubert, Markus; RelatedPerson: Zippe, Cornelius

For liquid fraction investigations in a rotating solid foam packed bed (RPB) angular-resolved time-averaged gamma-ray computed tomography (GammaCT) is applied. Liquid is injected by a 12 baffle disc injector. This repository contains:

  • the raw data of the gamma-ray CT scanner,
  • the extracted projection-averaged profile data matrix and
  • the restructured angular-resolved time-averaged sinogram data.

Keywords: Rotating Packed Bed; Process Intensivation; Computed Tomography

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Permalink: https://www.hzdr.de/publications/Publ-34853
Publ.-Id: 34853


RawData - Liquid fraction investigations in a RPB (solid foam, 32 baffles) using GammaCT

Bieberle, A.; Loll, R.; Pyka, T.; Schubert, M.
DataCollector: Bieberle, André; Researcher: Schubert, Markus; RelatedPerson: Zippe, Cornelius

For liquid fraction investigations in a rotating solid foam packed bed (RPB) angular-resolved time-averaged gamma-ray computed tomography (GammaCT) is applied. Liquid is injected by a 32 baffle disc injector. This repository contains:

  • the raw data of the gamma-ray CT scanner,
  • the extracted projection-averaged profile data matrix and
  • the restructured angular-resolved time-averaged sinogram data. 

Keywords: Rotating Packed Bed; Process Intensivation; Computed Tomography

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Publ.-Id: 34852


Liquid fraction investigations in a RPB with different foam and liquid inlet geometries using GammaCT

Bieberle, A.; Loll, R.; Pyka, T.; Schubert, M.

For liquid fraction investigations in a rotating packed bed (RPB) angular-resolved time-averaged gamma-ray computed tomography (GammaCT) is applied. Liquid is injected via different inlet geometries. This repository mainly contains the reconstructed CT data for the following configurations:

  • solid foam, 12 baffle liquid inlet
  • solid foam, 32 baffle liquid inlet
  • solid foam, single point liquid inlet
  • printed small zick-zack foam, multi point liquid inlet
  • printed small zick-zack foam, zero point liquid inlet
  • printed big zick-zack foam, multi point liquid inlet

Furthermore, the corresponding restructured sinogram raw data are included as well as diverse radiographic scans from different foam geometries that are used to arrange the RPB disc and the CT scanning plane as planar as possible and to define the vertically distributed scanning planes within the foams.

Keywords: Rotating Packed Bed; Process Intensivation; Computed Tomography

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Permalink: https://www.hzdr.de/publications/Publ-34851
Publ.-Id: 34851


Modeling COVID-19 Optimal Testing Strategies in Retirement Homes: An Optimization-based Probabilistic Approach

Davoodi Monfared, M.; Batista German, A. C.; Senapati, A.; Schlechte-Welnicz, W.; Calabrese, J.

Retirement Home facilities have been widely affected by the COVID-19 pandemic. The residents in these homes are usually elderly people with a high risk of mortality from being infected. Since they are in contact with each other, once an infection arrives at the facility, it propagates quickly. To prevent the outbreaks, it has been demonstrated that regular testing of the residents is the most practical approach. However, testing may result in extra time for the staff that performs the test as well as residents' discontent, which presents a trade-off between the time invested in testing, daily caring activities, and viral spread containment. We introduce a novel optimization approach for testing schedule strategies in retirement homes. We develop a mixed-integer linear programming model for balancing the staff’s workload while minimizing the expected detection time of a probable infection inside the facility. We present a probabilistic approach in conjunction with the optimization models to compute the risk of infection, including contact rates, incidence status, and the probability of infection of the residents. To tackle the combinatorial nature of the problem, we proved an efficient property, called symmetry property of optimal testing strategy and utilized it in proposing an enhanced local search algorithm. We perform several experiments with real-size instances and show that the proposed approach can derive optimal testing strategies.

Keywords: Retirement Home; Testing Strategy; COVID-19

  • Open Access Logo Lecture (Conference)
    ESPOO 2022, 03.-06.07.2022, Helsinki, Finland

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Publ.-Id: 34850


Pore network and solute flux pattern analysis towards improved predictability of diffusive transport in argillaceous host rocks

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

Clay rock formations are considered as host rocks for underground radioactive waste repositories. Reliable predictions of diffusive transport heterogeneity are critical for assessing the sealing capacity of argillaceous rocks. The predictive power of numerical approaches to flow field analysis and radionuclide migration depends on the quality of the underlying pore network geometry. Both sedimentary and diagenetic complexity are controlling factors.
In this study, we demonstrate a cross-scale approach to reconstruct the pore network geometries of the sandy facies of the Opalinus Clay rock. We identified diagenetic and sedimentary subfacies components based on the concentration of diagenetic carbonates and sulfides and grain size variability, and quantified their pore size distributions and pore network geometries. A viable approach for use in transport modeling is to combine μ-CT data segmentation followed by filling the resulting volumes with representative pore network geometries based on FIB-SEM data. The resulting generalized pore network geometries are applied in digital rock models to calculate effective diffusivities, using a combined upscaling workflow for transport simulations from nanometer to micrometer scales.
Positron emission tomography (PET) diffusion experiments validated the transport simulation results. We introduced a statistical treatment of the PET and μ-CT tomographic datasets based on the spatial variability of both PET tracer concentrations and rock density. The analyzed effective diffusivities confirmed the numerical results.
This study illustrates three important steps in migration analysis: (i) a workflow of general applicability for cross-scale identification of pore network data in argillaceous rocks, (ii) application of the pore network data for the numerical analysis of diffusive transport, and (iii) validation of numerical results via combined PET - μ-CT diffusion experiments. Although the conceptual approach is not feasible for large numbers of samples, it opens up a strong potential for generalization: the validated results of effective diffusivities can now be easily used in a variety of segmented geometries. This allows to efficiently test upscaling concepts for the continuum scale on this basis.

Keywords: Diffusive transport; Transport modeling; Positron emission tomography (PET); Opalinus Clay; Radionuclide migration; Nuclear waste

Permalink: https://www.hzdr.de/publications/Publ-34849
Publ.-Id: 34849


Chemical flowers: Buoyancy-driven instabilities under modulated gravity during a parabolic flight

Stergiou, Y.; Hauser, M. J. B.; Wit, A. D.; Schuszter, G.; Horvath, D.; Eckert, K.; Schwarzenberger, K.

This paper is associated with a video winner of the 2021 American Physical Society’s Division of Fluid Dynamics (DFD) Milton van Dyke Award for work presented at the DFD Gallery of Fluid Motion. The original video is available online at the Gallery of Fluid Motion, https://doi.org/10.1103/APS.DFD.2021.GFM.V0036.

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Permalink: https://www.hzdr.de/publications/Publ-34848
Publ.-Id: 34848


Viscous fingering in a non-Newtonian liquid radial displacement by surfactant (C14TAB)-polymer (Xanthnan Gum) interaction

Stergiou, Y.; Perrakis, A.; Keshavarzi, B.; Javadi, A.; Eckert, K.; Schwarzenberger, K.

We investigated a miscible displacement of a less viscous liquid by a more viscous shear-thinning liquid in a Hele-Shaw cell. Due to a coacervation
reaction between both liquids, a hydrodynamic instability appears in the form of inward viscous fingering. The liquids consisted of a solution of
the anionic biopolymer xanthan gum, as the injection liquid, which displaced a cationic surfactant (C14TAB) aqueous solution (Keshavarzi et al.,
2019). In the contact zone between the two solutions, the oppositely charged species form polymer-surfactant complexes due to electrostatic
interactions. The electrostatic and hydrophobic interactions between these complexes lead to a self-assembly process, forming a membrane
structure separated from the main solution. During the continuing radial displacement, a large variety of patterns can emerge which is attributed
to the rheological properties of the system involving viscosity gradients, the non-Newtonian nature of the displacing solution and the complex
rheology of the coacervate phase. Variation of the flow rate and gap width of the Hele-Shaw cell revealed distinct instability regimes and allowed
to identify main contributing mechanisms. These insights open the door for further investigation of fluid mechanics problems (i.e. Saffman-Taylor
instability) (Saffman & Taylor, 1958) in multiphase systems of complex rheology and its applications in engineering and technology.
References:
Keshavarzi, B., Langmuir. 2019, 35(42), 13624-13635.
Saffman, P., & Taylor, G. Proceedings of the Royal Society A: Mathematical, Physical. 1958, 245(1242), 312-329.
Acknowledgements: This work was supported by the German Aerospace Center (DLR) with funds provided by the Federal Ministry for
Economic Affairs and Energy (BMWi), Grant No. 50WM2061 (project ChemFront).

  • Lecture (Conference)
    Annual European Rheology Conference (AERC 2022), 26.-28.04.2022, Sevilla, Spain

Permalink: https://www.hzdr.de/publications/Publ-34847
Publ.-Id: 34847


Physics-Informed and Data-Driven Molecular Dynamics Simulations of Iron under Extreme Conditions

Ramakrishna, K.; Lokamani, M.; Nikolov, S.; Tranchida, J.; Wood, M.; Cangi, A.

We present a new Spectral Neighbor Analysis Potential (SNAP) machine-learning potential for large-scale molecular dynamics simulations of Iron. SNAP is a classical interatomic potential that expresses the energy of each atom as a linear function of selected bispectrum components of the neighbor atoms. The development of the SNAP potential entails three steps: (1) the creation of a training database comprised of a consistent and meaningful set of first-principles Density Functional Theory (DFT) data for Iron at a range of high pressures (0-400 GPa) and temperatures (0-6500 K); (2) the robust and physically guided training of the SNAP hyper-parameters based on DFT data using statistical data analysis; and (3) the validation of the SNAP potential in molecular dynamics simulations of Iron by evaluating transport properties at extreme conditions up to those prevalent in Earth's core.

Keywords: Warm dense matter; Matter under extreme conditions; Computational Physics

  • Poster
    Young Researcher's Workshop on Machine Learning for Materials 2022, 09.-13.05.2022, Trieste, Italy

Permalink: https://www.hzdr.de/publications/Publ-34846
Publ.-Id: 34846


Maskless magnetic patterning using cobalt and dysprosium focused ion beams

Lenz, K.; Pablo Navarro, J.; Klingner, N.; Hlawacek, G.; Samad, F.; Narkovic, R.; Hübner, R.; Pilz, W.; Meyer, F.; Mazarov, P.; Bischoff, L.; Lindner, J.

We present results for direct maskless magnetic patterning of ferromagnetic nanostructures using a special liquid metal alloy ion source for focused ion beam (FIB) systems. We used a Co36Nd64 alloy as the FIB source [1]. A Wien mass filter allows for quick switching between the ion species in the alloy without changing the FIB source. A 5000×1000×50 nm3 permalloy strip served as the sample. Using the FIB we implanted a 300-nm-wide track with Co ions (see Fig.1). We observed the Co-induced changes by measuring the sample with microresonator ferromagnetic resonance before and after the implantation. Structures as small as 30 nm can be implanted up to a concentration of 10 % near the surface. Such lateral resolution is hard to reach for other lithographic methods. This allows for easy magnetic modification of edge-localized spin waves.
In another set of samples, we implanted Dy ions to locally increase the damping in a stripe pattern of ~120-nm-wide strips with 400 nm periodicity on a total area of 1×1 mm². Thus, the Gilbert damping parameter can be easily increased by one order of magnitude with a lateral resolution of about 100 nm.
In contrast to electron beam lithography in combination with broad-beam ion implantation, the maskless FIB process does not require the cumbersome and difficult removal of the ion-hardened resist if optical measurements like BLS or TR-MOKE are needed.

Keywords: ferromagnetic resonance; focused ion beams; nanostructures; implantation

Related publications

  • Poster
    Magnonics 2022, 31.07.-04.08.2022, Oxnard, USA
  • Lecture (Conference)
    DPG-Tagung der Sektion Kondensierte Materie (SKM), 04.-09.09.2022, Regensburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34845
Publ.-Id: 34845


Nonstationary spin waves under a uniform excitation in a confined permalloy microstrip directly imaged with STXM-FMR

Pile, S.; Stienen, S.; Lenz, K.; Narkovic, R.; Wintz, S.; Förster, J.; Mayr, S.; Buchner, M.; Weigand, M.; Ney, V.; Lindner, J.; Ney, A.

Spin waves are one of the options to replace the transfer of electronic charges in logic devices to make information processing faster and more efficient [1]. A fundamental understanding of the dynamic magnetic properties of confined rectangular strips is a prerequisite for the development of nanoscale computational devices. Planar microresonators/microantennas made it possible not only to measure spin wave dynamics in a single microstrip, but to apply synchrotron-based time-resolved scanning transmission microscopy (TR-STXM) [3] using a phase-locked ferromagnetic resonance (FMR) excitation scheme (STXM-FMR). STXM-FMR enables direct temporally resolved imaging of the spatial distribution of the precessing magnetization within the microstrip during FMR excitation with elemental selectivity. FMR modes in a single rectangular permalloy microstrip were directly imaged using STXM-FMR and the findings were corroborated by micromagnetic simulations showing a very good agreement [5]. Under uniform excitation in a single confined microstrip typically standing spin waves are expected, nevertheless all imaged spin waves are nonstationary at and off resonance.

Keywords: ferromagnetic resonance; x-ray transmission microscopy; nanostructures

  • Invited lecture (Conferences)
    NESY User Symposium 2022, 29.-30.09.2022, Leoben, Österreich
  • Poster
    7. Conference on Magnonics 2022, 31.07.-04.08.2022, Oxnard, USA

Permalink: https://www.hzdr.de/publications/Publ-34844
Publ.-Id: 34844


Synthesis of novel PSMA ligands and preclinical evaluation of [99mTc]TcO-ABX474, a radioligand for SPECT imaging of prostate cancer

Ludwig, F.-A.; Lis, C.; Ullrich, M.; Lankau, H.-J.; Sihver, W.; Joseph, D.; Eiselt, E.; Meyer, C.; Gündel, D.; Deuther-Conrad, W.; Brust, P.; Donat, C. K.; Bachmann, M.; Pietzsch, H.-J.; Pietzsch, J.; Fischer, S.; Kopka, K.; Hoepping, A.

Objectives: During the last 15 years several PSMA PET ligands for prostate cancer imaging have been developed resulting in the recent approvals of 68Ga-PSMA-11, 18F-PSMA-1007 and 18F-DCFPyL.[1,2] However, 99mTc remains a popular radiometal for SPECT imaging due to its longer half-life and availability from 99Mo/99mTc generators especially in outpatient imaging centers. Due to the widespread availability of SPECT cameras PSMA SPECT ligands have the potential to substantially extend the availability of PSMA-based imaging, but currently no PSMA SPECT ligand is approved. MIP-1404, PSMA-I&S and HYNIC-iPSMA are rare examples of PSMA SPECT tracers in clinical development. Accordingly, the aim of our study was to develop a PSMA ligand for 99mTc SPECT imaging of prostate cancer based on an N2S2 chelator, which enables reliable radiolabeling to form stable 99mTc complexes.[3]

Methods: A number of compounds, which contain the PSMA binding motif Glu-urea-Lys, a varying linker and a bisaminothiol (BAT)-type N2S2 chelator, were synthesized. Selected compounds were radiolabeled with 99mTc, followed by assessment of in vitro stability of the formed complexes via radio-HPLC. The specific binding affinity towards PSMA and the internalization of the radioligands were examined in LNCaP cells, supplemented by autoradiographic studies. Tissue distribution and tumor accumulation were evaluated in LNCaP-tumor bearing mice via quantitative SPECT/CT imaging, benchmarked with [99mTc]Tc-PSMA-I&S[4] and [68Ga]Ga-PSMA-11.

Results: Among the six 99mTc radioligands synthesized and examined, [99mTc]TcO-ABX474 showed most favorable properties. Radiolabeling of ABX474 (50 µg) was achieved starting from [99mTc]NaTcO4 (0.2-2 GBq) in saline (1.4 mL) using SnCl2 (1 µg in 0.01 M HCl) as reducing agent, in presence of calcium-D-heptagluconate (10 µg) and D-mannitol (1 mg) at pH 5-6. Incubation at r.t. for 20 min followed by heating at 80°C for 20 min afforded the product-containing solution with a radiochemical purity of 93.8 ± 3.1 % (n=20) optimization planned during kit development). [99mTc]TcO-ABX474 was stable in DPBS (96.7 ± 2.1 % unchanged, n=3) at 25°C for 20 h as well as in mouse plasma (96.7 ± 1.3 % unchanged, n=3) and human plasma (91.7 ± 0.3 % unchanged, n=5) at 37°C for 6 h, respectively. [99mTc]TcO-ABX474 showed high binding affinity towards PSMA (Kd= 7.2 ± 1.7 nM) and substantial uptake in LNCaP cells (binding: 3.2 %AD/mg protein internalization: 2.8 %AD/mg protein, 47% internalization of total cell bound activity at 37°C).
In LNCaP xenograft mice, [99mTc]TcO-ABX474 showed high PSMA-specific tumor uptake, mainly renal excretion and moderate kidney retention. Hence, [99mTc]TcO-ABX474 exhibited higher tumor-to-background ratios (SUV) between 1‒4 hours after injection (tumor/muscle: 25.2‒52.7 tumor/kidney: 0.3‒0.37) compared to the reference compound [99mTc]Tc-PSMA-I&S (tumor/muscle: 5.7‒18.2 tumor/kidney: 0.17‒0.2). [99mTc]TcO-ABX474 allowed for similar tumor visualization compared to PET/CT imaging with [68Ga]Ga-PSMA-11 (tumor/muscle: 22.9 tumor/kidney: 0.24) 1 hour after injection.

Conclusion: This study demonstrates that [99mTc]TcO-ABX474 is a promising radiotracer candidate for PSMA-specific SPECT imaging of prostate cancer warranting further clinical evaluation.

Acknowledgments: The authors would like to thank the Sächsische Aufbaubank - Förderbank - for financial support (100363946).

References:

[1] https://www.fda.gov/drugs/news-events-human-drugs/fda-approves-second-psma-targeted-pet-imaging-drug-men-prostate-cancer, published on 27/05/2021.

[2] https://www.has-sante.fr/jcms/p_3337433/en/radelumin-18f-psma-1007-cancer-de-la-prostate, published on 04/05/2022.

[3] Hoepping, A. et al., EPO Patent Application EP22174909.6, 23/05/2022.

[4] Robu, S. et al., J Nucl Med 2017, 58, 235-242.

  • Lecture (Conference)
    TERACHEM 2022: The Fourth International Symposium on Technetium and Other Radiometals in Chemistry and Medicine, 14.-17.09.2022, Bressanone (Brixen), Italien
    DOI: 10.1016/S0969-8051(22)02136-9
  • Abstract in refereed journal
    Nuclear Medicine and Biology 114-115(2022), S19
    DOI: 10.1016/S0969-8051(22)02136-9

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-34843
Publ.-Id: 34843


CMOS-compatible manufacturability of sub-15 nm Si/SiO2/Si nanopillars containing single Si nanodots for single electron transistor applications

Borany, J.; Engelmann, H.-J.; Heinig, K.-H.; Amat, E.; Hlawacek, G.; Klüpfel, F.; Hübner, R.; Möller, W.; Pourteau, M.-L.; Rademaker, G.; Rommel, M.; Baier, L.; Pichler, P.; Perez-Murano, F.; Tiron, R.

This study addresses the complementary metal-oxide-semiconductor-compatible fabrication of vertically stacked Si/SiO2/Si nanopillars (NPs) with embedded Si nanodots (NDs) as key functional elements of a quantum-dot-based, gate-all-around single-electron transistor (SET) operating at room temperature. The main geometrical parameters of the NPs and NDs were deduced from SET device simulations using the nextnano++ program package. The basic concept for single silicon ND formation within a confined oxide volume was deduced from Monte-Carlo simulations of ion-beam mixing and SiOx phase separation. A process flow was developed and experimentally implemented by combining bottom-up (Si ND self-assembly) and top-down (ion-beam mixing, electron-beam lithography, reactive ion etching) technologies, fully satisfying process requirements of future 3D device architectures. The theoretically predicted self-assembly of a single Si ND via phase separation within a confined SiOx disc of < 500 nm³ volume was experimentally validated. This work describes in detail the optimization of conditions required for NP/ND formation, such as the oxide thickness, energy and fluence of ion-beam mixing, thermal budget for phase separation and parameters of reactive ion beam etching. Low-temperature plasma oxidation was used to further reduce NP diameter and for gate oxide fabrication whilst preserving the pre-existing NDs. The influence of critical dimension variability on the SET functionality and options to reduce such deviations are discussed. We finally demonstrate the reliable formation of Si quantum dots with diameters of less than 3 nm in the oxide layer of a stacked Si/SiO2/Si NP of 10 nm diameter, with tunnelling distances of about 1 nm between the Si ND and the neighboured Si regions forming drain and source of the SET.

Keywords: CMOS; single-electron transistor; nanostructure fabrication; nanpillars; silicon nanodot; self-organization; ion-beam mixing

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Permalink: https://www.hzdr.de/publications/Publ-34842
Publ.-Id: 34842


PET Imaging of Cholinergic Neurotransmission in Neurodegenerative Disorders

Tiepolt, S.; Meyer, P. M.; Patt, M.; Deuther-Conrad, W.; Hesse, S.; Barthel, H.; Sabri, O.

As a neuromodulator, the neurotransmitter acetylcholine plays an important role in cognitive, mood, locomotor, sleep/wake, and olfactory functions. In the pathophysiology of
most neurodegenerative diseases, such as Alzheimer disease (AD) or Lewy body disorder (LBD), cholinergic receptors, transporters, or enzymes are involved and relevant as
imaging targets. The aim of this review is to summarize current knowledge on PET imaging of cholinergic neurotransmission in neurodegenerative diseases. For PET imaging
of presynaptic vesicular acetylcholine transporters (VAChT), (-)-18F-fluoroethoxybenzovesamicol (18F-FEOBV) was the first PET ligand that could be successfully translated
to clinical application. Since then, the number of 18F-FEOBV PET investigations on patients with AD or LBD has grown rapidly and provided novel, important findings
concerning the pathophysiology of AD and LBD. Regarding the α4β2 nicotinic acetylcholine receptors (nAChRs), various second-generation PET ligands, such as 18F-nifene,
18F-AZAN, 18F-XTRA, (-)-18F-flubatine, and (+)-18F-flubatine, were developed and successfully translated to human application. In neurodegenerative diseases such as AD
and LBD, PET imaging of α4β2 nAChRs is of special value for monitoring disease progression and drugs directed to α4β2 nAChRs. For PET of α7 nAChR, 18F-ASEM and
11C-MeQAA were successfully applied in mild cognitive impairment and AD, respectively. The highest potential for α7 nAChR PET is seen in staging, in evaluating disease
progression, and in therapy monitoring. PET of selective muscarinic acetylcholine receptors (mAChRs) is still in an early stage, as the development of subtype-selective
radioligands is complicated. Promising radioligands to image mAChR subtypes M1 (11C-LSN3172176), M2 (18F-FP-TZTP), and M4 (11C-MK-6884) were developed and
successfully translated to humans. PET imaging of mAChRs is relevant for the assessment and monitoring of therapies in AD and LBD. PET of acetylcholine esterase activity
has been investigated since the 1990s. Many PET studies with 11C-PMP and 11C-MP4A demonstrated cortical cholinergic dysfunction in dementia associated with AD and
LBD. Recent studies indicated a solid relationship between subcortical and cortical cholinergic dysfunction and noncognitive dysfunctions such as balance and gait in LBD.
Taken together, PET of distinct components of cholinergic neurotransmission is of great interest for diagnosis, disease monitoring, and therapy monitoring and to gain insight
into the pathophysiology of different neurodegenerative disorders.

Keywords: acetylcholine; Alzheimer disease; Lewy body disorder; neurodegenerative disorde; neurology; PET

Permalink: https://www.hzdr.de/publications/Publ-34841
Publ.-Id: 34841


Assessment of the flow modulation technique for measuring axial liquid dispersion coefficients in trickle-bed reactors

Marchini, S.; Bieberle, A.; Schubert, M.; Hampel, U.

This study proposes a novel non-intrusive approach for measuring axial liquid dispersion coefficients in trickle-bed reactors. The approach is based on the flow modulation technique (FMT), which replaces traditional tracer substance injections with a marginal sinusoidal modulation superimposed on the liquid inlet flow. The modulation causes a sinusoidal variation of the liquid holdup in time, i.e. liquid holdup wave. Downstream the inlet, the holdup wave gets damped in amplitude and shifted in phase due to dispersion. Amplitude damping and phase shift are experimentally measured and related to the value of the axial dispersion coefficient using a one-dimensional dispersion model. Recently, the flow modulation has been applied to investigate the axial gas dispersion coefficient in bubble columns. In this study, the approach is adapted to measure liquid dispersion in co-current gas-liquid trickle-bed reactors. In addition, the consequences of the assumptions requested by the axial dispersion model are discussed. Furthermore, the impact of the experimental flow modulation parameters on sensitivity and uncertainty of the dispersion coefficient is analyzed.

Keywords: liquid flow modulation; axial liquid dispersion coefficient; trickle-bed reactors

  • Contribution to proceedings
    15th International Conference on Gas–Liquid and Gas–Liquid–Solid Reactor Engineering (GLS-15), 07.-10.08.2022, Ottawa, Canada
    Assessment of the flow modulation technique for measuring axial liquid dispersion coefficients in trickle-bed reactors

Permalink: https://www.hzdr.de/publications/Publ-34840
Publ.-Id: 34840


Air-stripping of isobutyl acetate in aqueous solution for measuring tray and point efficiencies in hydraulic air/water column mockups

Marchini, S.; Vishwakarma, V.; Schubert, M.; Brunazzi, E.; Hampel, U.

The knowledge of the tray efficiency value is crucial for a correct design of tray columns [1]. In the last decades, several models have been developed for predicting the tray efficiency value, given the point efficiency. Validation of these models requires determining both tray and point efficiency experimentally.
The tray efficiencies are mostly determined by sampling the incoming and exiting streams of liquid and gas over the tray. On the contrary, experimentally determining point efficiencies is technically challenging and thus, their value is often derived from correlations or small-scale experiments (e.g. Oldershaw columns). Only few studies on the experimental determination of point efficiencies on large-scale distillation trays exist (e.g. [2], [3]). The physical systems used in these studies pose several technical restrictions and safety concerns. For these reasons, a setup designed ad hoc for point efficiency studies is mostly needed.
Recently Marchini et al. [4] proposed the stripping of isobutyl acetate from an aqueous solution using air as a physical system,which was proven to offer several advantages over the traditional ones and to be readily integrated into existing cold fluid air/water mockups without any major modification. The authors also showed how the tray-to-point efficiency ratio can be determined based on the liquid concentration distribution on the tray, accounting for liquid mixing phenomena in both the axial and transversal directions.
In this study, the tray and point efficiency values of an 800 mm dia. distillation sieve tray were determined at different gas and liquid flow rates by sampling the liquid at different deck locations for subsequent UV-spectroscopy, obtaining the liquid concentration distribution (Figure 1).

Keywords: distillation tray; tray efficiency; weeping

  • Contribution to proceedings
    Distillation and Absorption 2022, 18.-21.09.2022, Toulouse, France
    Proceedings of Distillation and Absorption 2022

Permalink: https://www.hzdr.de/publications/Publ-34839
Publ.-Id: 34839


Np(V) sorption onto zirconia: a combined spectroscopy, batch and modeling study

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

When assessing the long-term safety of a nuclear waste repository, the interactions of dissolved long-lived radionuclides, such as the actinide neptunium, with corroded phases in the near-field of the repository have to be considered. Zirconia (ZrO₂) is the main corrosion product of the zircaloy cladding material of nuclear fuel rods and can constitute a first barrier against the release of mobilized radionuclides into the environment.
To gain a detailed understanding of the Np(V) sorption processes at the zirconia‒water interface, a comprehensive multimethod approach was pursued. Molecular level information about the Np(V) surface species were derived by in situ Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR FT-IR) and Extended X-ray Absorption Fine Structure Spectroscopy (EXAFS). The Np L₃-absorption edge (17,610 eV) is commonly used for EXAFS investigations of neptunium. However, the Zr K absorption edge (17,998 eV) is close in energy to the Np L₃-edge, reducing the k-range that can be evaluated. Since attempts to use the Np L₂-edge (21,600 eV) with an energy above the Zr K-edge were not successful, the Np L₃-edge EXAFS spectra had to be used to gain information about the molecular environment of the sorbed Np(V) surface species. The short Np-Zr distance of approximately 3.6 Å derived from EXAFS spectra revealed the predominant formation of bidentate inner-sphere Np(V) surface complexes. ATR FT-IR experiments were conducted at different pH values and a shift of the asymmetric stretching vibration of Np(V) (𝜈₃(NpO₂⁺) towards lower energies was observed at acidic pH, revealing the interactions between Np(V) and ZrO₂. Furthermore, the sorption process was only slightly reversible, also indicating the formation of Np(V) inner-sphere complexes. However, with increasing pH, vibrational surface modes of the ZrO₂ matrix appeared, which were overlapping with Np(V) stretching frequency and impeding the investigation of the pH-dependent surface speciation of Np(V).
Batch sorption experiments (varying ionic strength, Np(V) concentration, and solid-to-liquid ratio (m/V)) as well as a sorption isotherm experiment at pH 6 were conducted to study the sorption processes of the Np(V)‒ZrO₂ system on the macroscopic scale. The sorption of Np(V) was independent of ionic strength, also indicating the formation of Np(V) inner-sphere surface complexes. This was supported by zeta potential measurements in the presence of neptunium, where a shift to higher pH values of the isoelectric point of the neat ZrO₂ was observed. With increasing m/V the Np(V) sorption edge was shifted towards lower pH values, indicating the presence of different kinds of sorption sites, which was also deduced from the shape of the sorption isotherm.
Reliable information about the number and denticity of surface species obtained by spectroscopic and macroscopic investigations enable modeling approaches such as surface complexation modeling (SCM) to be robust. The results derived by SCM will in turn contribute to a more reliable prediction of the environmental fate of neptunium.

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

Related publications

  • Lecture (Conference)
    ATAS-AnXAS 2022 5th International Workshop on Advanced Techniques in Actinide Spectroscopy 9th Workshop on Speciation, Techniques and Facilities for Synchrotron Radiation, 17.-21.10.2022, Grenoble, France

Permalink: https://www.hzdr.de/publications/Publ-34837
Publ.-Id: 34837


Spectroscopic investigations of the U(VI) sorption onto the zircaloy corrosion product ZrO2

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

For a safety assessment of a repository for nuclear waste, the interactions of actinides with corroded phases in the near-field must be taken into account. Most commercial fission reactors use uranium-based fuels and the spent nuclear fuel still contains approximately 95 % of uranium, making it the largest fraction of the spent nuclear fuel by mass. Zirconia (ZrO₂) is the main corrosion product of the zircaloy cladding material of nuclear fuel rods and can act as a first barrier against the release of mobilized radionuclides from the spent nuclear fuel into the environment. Furthermore, the complexation of dissolved radionuclides with common inorganic ligands, such as carbonate, in the groundwater can have a significant influence on the formation and structure of actinide surface species and thus their mobility in the environment.
In situ Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR FT-IR) and Extended X-ray Absorption Fine Structure Spectroscopy (EXAFS) were applied to investigate the U(VI) speciation at the ZrO₂-water interface. A pH-dependent speciation of U(VI) at the zirconia surface could be observed under inert gas conditions with EXAFS and the preliminary results indicated the presence of two inner-sphere U(VI) surface species with different structural environments. The EXAFS results can be compared to the literature results of Lomenech et al., where also two U(VI) surface species on the ZrO₂ surface were observed (a tridentate U(VI) surface species at pH 3 and a bidentate surface species at higher pH) [1,2].
The sorption of U(VI) onto ZrO₂ under inert gas conditions was also studied with ATR FT-IR at pH 3.5 and 5.5 and a pH-dependent U(VI) speciation was observed, supporting the findings from the EXAFS investigations. The observed red shift of the asymmetric stretching vibration of the free uranyl aqua ion (𝜈₃(UO₂²⁺)) in the presence of ZrO₂ at pH 5.5 was due to the U(VI)‒ZrO₂ interactions. At a lower pH of 3.5 a second U(VI) surface species with a less pronounced red shift of the ν₃ vibration was identified.
A pH-dependence of the sorption of atmospheric carbonate on the zirconia surface was observed and a spectral splitting (Δ𝜈) of approximately 200 cm⁻¹ of the symmetric and asymmetric stretching vibration modes indicated the presence of bidentate bound carbonate species on the surface. The U(VI) sorption onto zirconia pre-equilibrated with atmospheric carbonate was also studied at pH 5.5 and 3.5. Compared to the experiments conducted under inert gas conditions, the red shift of the ν₃ mode of U(VI) at pH 5.5 was more pronounced in the presence of carbonate, indicating an influence of carbonate on the formed U(VI) surface species. In addition, changes in the frequency of the asymmetric and symmetric stretching vibrations of carbonate sorbed to the zirconia surface were observed in the presence of U(VI), also hinting towards structural changes in the surface species.
EXAFS and ATR FT-IR investigations provided valuable structural information about the formed U(VI) sorption species on the ZrO₂ surface in the presence and absence of carbonate. The improved molecular level understanding of such sorption processes will enable more reliable predictions of the environmental fate of U(VI). Such results will be complemented with batch sorption experiments as well as thermodynamic surface complexation modeling.

[1] Lomenech, C. et al. (2003) Radiochim. Acta 91(8), 453-461.
[2] Lomenech, C. et al. (2003) J. Colloid Interface Sci. 261(2), 221-232.

Keywords: uranium(VI); zirconia; ZrO₂; spectroscopy; IR; EXAFS; carbonate; sorption

Related publications

  • Poster
    ATAS-AnXAS 2022 5th International Workshop on Advanced Techniques in Actinide Spectroscopy 9th Workshop on Speciation, Techniques and Facilities for Synchrotron Radiation, 17.-21.10.2022, Grenoble, France

Permalink: https://www.hzdr.de/publications/Publ-34836
Publ.-Id: 34836


Magnetically Sensitive Electronic Skins for Supervised Folding of Origami Actuators

Oliveros Mata, E. S.; Makushko, P.; Ha, M.; Canon Bermudez, G. S.; Liu, J. A.-C.; Evans, B. A.; Tracy, J. B.; Makarov, D.

Soft actuators are required to deform, fold, or unfold in order to interact with their surroundings.[1] One strategy to achieve the movement of mechanically soft systems is the use of magnetic fields for untethered actuation. Flexible magnetic composites have been demonstrated as functional grippers, rollers, and walkers upon applied external magnetic fields.[2] Being controlled with electromagnetic coils, magnetic actuators can profit from high-speed actuation to quickly respond to their environment.[3]

The development of an appropriate sensory tracking system for soft actuators is a research topic with open challenges. Light, conformal, and mechanically imperceptible sensing systems are to be developed to be compatible with soft actuators. In this work, we present flexible magnetosensitive electronic skin which relies on thin-film magnetic field sensors to enable onboard folding control of origami-like soft actuators. The flexible electronic skin consists of thin film giant magnetoresistive GMR and Hall effect sensors that are used to measure the magnetization state of the actuator, the applied magnetic fields, and the completeness of the bending process. The resulting intelligent material is mechanically designed to fold even when the flexible magnetic skin is attached to the soft actuator.[4]

The magnetic origami actuators are made of thin DiAPLEX foils, a shape memory polymer, with embedded NdFeB particles. Such composite can be used to achieve magnetically induced motion using magnetic fields and a directed light source to increase locally the temperature. We experimentally found the best thickness (60 µm) and concentration (40 NdFeB wt%) parameters to achieve magnetic folds.[4]

The integration of magnetic soft actuators with e-skins allowed self-guided assembly of the origami foils. We showed two case studies showing that this approach is useful for assembling boxes and boat-like origami shapes. This integration process was monitored, followed, and controlled by the output of the laminated sensors. [4]

[1] A. Miriyev, et al. Nat. Commun. 8, 596 (2017)

[2] S. Wu, et al. Multifunct. Mater. 3, 042003 (2020)

[3] X. Wang, et al. Commun. Matter. 1, 67 (2020)

[4] M. Ha, et al. *Adv. Mater. 33, 2008751 (2021)

  • Lecture (Conference)
    67th Annual Conference on Magnetism and Magnetic Materials (MMM 2022), 31.10.-04.11.2022, Minneapolis, United States

Permalink: https://www.hzdr.de/publications/Publ-34835
Publ.-Id: 34835


Detecting Magnetic Fields with Printed Magnetoresistive Sensors on Rigid and Flexible Substrates

Oliveros Mata, E. S.; Voigt, C.; Makushko, P.; Xu, R.; Ha, M.; Canon Bermudez, G. S.; Kosub, T.; Mönch, J. I.; Zabila, Y.; Illing, R.; Wang, Y.; Valdez-Garduño, N. M.; Fritsch, M.; Mosch, S.; Kusnezoff, M.; Faßbender, J.; Vinnichenko, M.; Makarov, D.

The development of functional printable materials enables the production of electronic components in unconventional materials and different form factors[1]. Here, we show magnetically sensitive inks/pastes based on magnetoresistive powder that can be printed via stencil, dispenser, or screen printing. We employ bismuth microparticles[2] as well as [Co/Cu], [Py/Cu],[3] and permalloy [4] flakes showing giant, anisotropic, or non-saturating large magnetoresistance, respectively.

We demonstrate that magnetic field sensors based on various types of magnetoresistive flakes can be printed onto rigid, flexible, and deformable substrates. We employed block-copolymers and elastic binders to enable mechanical resilience of these sensors: they can withstand bending down to 16 µm, 100% of stretching, and bending for hundreds of cycles without losing functionality.[3]

Additionally, by automatizing the dispenser printing process of bismuth-based pastes, we demonstrate the production of fully printed magnetic field sensors. The use of a micro-optically optimized high-power diode laser array provided a versatile approach for selective sintering of sensors over flexible foils in areas exceeding several square centimeters. In this work we experimentally confirm that such sensors retain their non-saturating magnetoresistive performance (MR = 146%) in high field conditions, allowing operation above 5 T. [2]

Our printed magnetic field sensors can be used to create interfaces that are responsive to magnetic fields through remote human input. Being flexible, they can be laminated on the skin, or stuck onto any object, from a desk to a house wall. We demonstrate the capabilities of printed magnetic field sensors to work as an interface to navigate through digital maps, as input panels for smart home applications, and as interactive wallpapers.

[1] A. Kamyshny, et al. 1905279 (2020) *Chem. Soc. Rev.* **48**, 1712 (2019)

[2] E.S. Oliveros-Mata, et al. *Appl. Phys. A* **127,** 280 (2021)

[3] M. Ha, et al. *Adv. Mater.* **33,** 2005521 (2021)

[4] E.S. Oliveros‐Mata, E. S., C. Voigt, et al. *Adv. Mater. Technol.* 2200227 (2022)

  • Lecture (Conference)
    67th Annual Conference on Magnetism and Magnetic Materials (MMM 2022), 31.10.-04.11.2022, Minneapolis, United States

Permalink: https://www.hzdr.de/publications/Publ-34834
Publ.-Id: 34834


New analytical tools for studying habitat selection in terrestrial mammals

Alston, J.; Fleming, C. H.; Calabrese, J.

The study of habitat selection is a foundational component of basic and applied animal ecology. Today, habitat selection in mammals is primarily studied using resource selection functions, a class of models that uses logistic regression to compare “used” to “available” habitat. However, these models have several statistical problems, including rampant pseudoreplication from failing to account for autocorrelation in modern animal movement data, no clear guidelines for sampling available habitat, and large amounts of numerical error from sampling too few available points. These problems are widely acknowledged but have no generally accepted solutions, so we propose three new methods for addressing them: likelihood weighting, Gaussian availability sampling, and numerical convergence checks. We demonstrate the practical advantages of these methods over conventional approaches using simulations and empirical data on a water mongoose (Atilax paludinosus), a caracal (Caracal caracal), and a serval (Leptailurus serval), and briefly demonstrate how to apply our methods to animal tracking data using the ‘ctmm’ R package. Broad uptake of these methods could substantially improve our estimates of habitat selection in mammals.

  • Lecture (Conference)
    American Society of Mammalogists Annual Meeting, 16.-21.06.2022, Tucson, AZ, USA

Permalink: https://www.hzdr.de/publications/Publ-34830
Publ.-Id: 34830


MRI magnitude signal-based proton beam visualisation in water phantoms reflects composite effects of beam-induced buoyant convection and radiation chemistry

Schieferecke, J.; Gantz, S.; Karsch, L.; Pawelke, J.; Hoffmann, A. L.

Objective. Local magnetic resonance (MR) signal loss was previously observed during proton beam
irradiation of free-floating water phantoms at ambient temperature using a research prototype in-
beam magnetic resonance imaging (MRI) scanner. The emergence of this MR signal loss was
hypothesised to be dependent on beam-induced convection. The aim of this study was therefore to
unravel whether physical conditions allowing the development of convection must prevail for the
beam-induced MRI signatures to emerge. Approach. The convection dependence of MRI magnitude
signal-based proton beam visualisation was investigated in combined irradiation and imaging
experiments using a gradient echo (GE)-based time-of-flight (ToF) angiography pulse sequence,
which was first tested for its suitability for proton beam visualisation in free-floating water phantoms
at ambient temperature. Subsequently, buoyant convection was selectively suppressed in water
phantoms using either mechanical barriers or temperature control of water expansivity. The
underlying contrast mechanism was further assessed using sagittal imaging and variation of T1
relaxation time-weighting. Main results. In the absence of convection-driven water flow, weak beam-
induced MR signal changes occurred, whereas strong changes did occur when convection was not
mechanically or thermally inhibited. Moreover, the degree of signal loss was found to change with the
variation of T1-weighting. Consequently, beam-induced MR signal loss in free-floating water
phantoms at ambient temperature does not exclusively originate from buoyant convection, but is
caused by local composite effects of beam-induced motion and radiation chemistry resulting in a local
change in the water T1 relaxation time. Significance. The identification of ToF angiography sequence-
based proton beam visualisation in water phantoms to result from composite effects of beam-induced
motion and radiation chemistry represents the starting point for the future elucidation of the currently
unexplained motion-based MRI contrast mechanism and the identification of the proton beam-
induced material change causing T1 relaxation time lengthening.

Keywords: magnetic resonance imaging; MRI; in-beam MRI; proton therapy; proton beam visualisation; convection; oxygen depletion

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Permalink: https://www.hzdr.de/publications/Publ-34828
Publ.-Id: 34828


Transferability of DFT surrogate models: Temperature and system size

Fiedler, L.; Cangi, A.

While Density Functional Theory (DFT) is the most common tool for the investigation of materials under extreme conditions, its scaling behavior with respect to both system size and temperature makes large scale simulations challenging. Yet, progress in this regard would enable accurate modeling of planetary interiors or radiation damage in fusion reactor walls.
One possible route to alleviate these scaling problems is through the use of surrogate models, i.e., machine-learning models. These are trained on DFT data and are able to reproduce DFT observables at comparable accuracy, but negligible computational cost.
In order to actually be useful for such investigations, existing models need to be able to work across length scales and be transferable within desired temperature ranges. Here we show how models based on local mappings of electronic structure information [1], implemented in the Materials Learning Algorithms (MALA) package [2] can be trained on small number of atoms and select temperatures, yet perform accurately when used to make predictions for extended systems within a range of temperatures.

Keywords: Density Functional Theory; Machine Learning

  • Poster
    Strongly Coupled Coulomb Systems 2022, 24.-29.07.2022, Görlitz, Deutschland
  • Lecture (Conference)
    Multiscale Modeling of Matter under Extreme Conditions, 11.-16.09.2022, Görlitz, Deutschland
  • Poster
    Big data analytical methods for complex systems, 06.10.2022, Wrocław, Polen

Permalink: https://www.hzdr.de/publications/Publ-34827
Publ.-Id: 34827


Data publication: Curvilinear spin-wave dynamics beyond the thin-shell approximation: Magnetic nanotubes as a case study

Körber, L.; Verba, R.; Otálora, J. A.; Kravchuk, V.; Lindner, J.; Faßbender, J.; Kakay, A.

This dataset contains the numerical data for our publication "Curvilinear spin-wave dynamics beyond the thin-shell approximation: Magnetic nanotubes as a case study" published in Physical Review B. The data consists of dispersion, magnetization ground states and mode profiles of spin waves in vortex-state magnetic nanotubes of different thicknesses, and has been calculated with the TetraX micromagnetic modeling package. All calculations are described within each subfolder by a jupyter notebook.

Keywords: spin waves; nanotubes; curvilinear magnetism; curvature effects; micromagnetic modeling; tetrax; nonreciprocity

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Permalink: https://www.hzdr.de/publications/Publ-34826
Publ.-Id: 34826


The M4,5 edges HERFD XANES: approaches to calculations

Amidani, L.; Kvashnina, K.

X-ray Absorption Near-Edge Structure (XANES) in the High-Energy-Resolution Fluorescence Detected Mode (HERFD) is a very powerful technique for actinide systems. The M4,5 edges are of particular interest because they probe directly 5f states. However, before the advent of HERFD they were scarcely used because the large core-hole lifetime broadening results in broad and featureless spectra. With the improved resolution of the HERFD mode, the characterristic edge shift of different oxidation states is well resolved and several spectral features are observed in M4,5 HERFD XANES of actinides. The richness of physicochemical information coded in the spectra are hard to extract due to the complexity of XANES interpretaion and drawing conclusions on the system under study is not trivial.

In this regards, spectral calculations are fundamental for a correct interpretation. Calculating HERFD XANES on actinide systems is however particularly challenging. Relativistic effects, spin-orbit and interelectronic interactions and the influence of the atomic environment are all relevant and need to be considered in calculations. In last years, despite several approaches has been used with promising results, we still miss a theoretical framework that can address the complexity of M4,5 HERFD XANES on actinide systems.

In this presentation we will report the results we obtained with a DFT-based approach on the M4 edge of U6+ systems. Our results will be compared with works done with other approaches in order to give an overview of the level of agreement with experimental data that can be reached today. Special emphasis will be given to the investigation of covalency of 5f states.

Related publications

  • Lecture (Conference)
    Actinide revisited 2022, 21.-23.09.2022, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-34825
Publ.-Id: 34825


Magnetic-field-assisted electrodeposition at conically structured metal layers

Huang, M.

Micro- and nano-sized conical structures possess specific magnetic, superhydrophobic and electrocatalytic properties and are therefore attractive for numerous applications. Among the various methods of manufacturing such structured layers, electrodeposition appears a simple and inexpensive method. Beside the use of capping agents, the application of magnetic fields could support the local growth of cones on a non-templated planar electrode.
This dissertation investigates electrodeposition at conically structured metal layers in external magnetic fields. Depending on the direction and the intensity of the magnetic field, the Lorentz force and the magnetic gradient force can generate electrolyte flow and bring electrolyte enriched with metal ions towards the cone tips. As a result, the local deposition rate is increased and conical growth is promoted. In order to obtain a basic understanding of the magnetic field effects, systematic numerical and theoretical investigations are performed for electrodeposition at mm-sized cones of different materials, shapes and arrangements under different electrochemical and magnetic conditions. If a uniform external magnetic field is oriented parallel to the cone axis, the magnetic gradient force enabled by the magnetization of ferromagnetic cones provides a strong support for conical growth, thereby often dominating over the Lorentz force and the buoyancy force arising from electrode reactions. This supporting effect is only slightly mitigated when neighboring cones are getting closer. The numerical results shown are validated by experimental data for different configurations and deposition parameters.
In order to explore the prospects of magnetic fields to enhance the growth of smaller, micro- and nanometer sized conical structures, scaling laws of the local flows driven by the magnetic forces are derived numerically and confirmed analytically for shrinking cone sizes. Although the magnetic gradient force can generate a beneficial flow at ferromagnetic cones, the small flow region and the nearly constant thickness of the concentration boundary layer limit the support of the magnetic field. Enhancements of the structuring effect are observed for pulsed deposition and, despite only moderately, at higher magnetic field intensities. Furthermore, a simplified modeling approach is developed to simulate the growth mechanism of nano-cones with respect to the influence of capping agents.
Experimental results of the electrodeposition of Ni cones in magnetic fields obtained by partners in Krakow are analyzed by performing simulations of both the global cell flow and the local flows generated by magnetic fields of different orientations. This two-step approach provides an interpretation of the experimental results, and gives a deeper insight on how the capping agent influences the local growth.
Finally, the impact of the hydrogen side reaction on the electrodeposition in magnetic fields is considered. The numerical results indicate that hydrogen bubbles sitting at the cone tips may damp conical growth, while the magnetic-field-driven flow imposes a weak stabilizing force on the bubble.

Keywords: Metal electrodeposition; Nano-structured catalyst; Lorentz force; Magnetic gradient force; Numerical simulation; Magnetic field

  • Doctoral thesis
    TU Dresden, 2022
    Mentor: Dr. Gerd Mutschke, Prof. Kerstin Eckert

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Permalink: https://www.hzdr.de/publications/Publ-34824
Publ.-Id: 34824


Nonlinear THz spectroscopy of two-dimensional systems

Helm, M.

Nonlinear THz spectroscopy of two-dimensional systems (pump-probe in graphene, with and without magnetic field, dressed microcavity polaritons).

Keywords: THz; free-electron laser; graphene; Landau levels; polariton

  • Invited lecture (Conferences)
    Workshop on "Semiconductors,nanostructures, 2D systems, and Dirac matter", 20.-22.06.2022, Grenoble, France

Permalink: https://www.hzdr.de/publications/Publ-34823
Publ.-Id: 34823


Learning local dominant force balances in active particle systems

Sturm, D.; Maddu, S.; Sbalzarini, I. F.

Systems of self-propelled particles exhibit self-organized collective behavior that leads to the formation of complex spatio-temporal patterns that can be observed all over nature — from the active self-assembly of microtubules in cells through the action of kinesin motor proteins, to flocking birds. Because of their abundance, the question of how these rich macroscopic structures emerge from the microscopic interactions of their constituents remains of central interest. While there exist several hydrodynamic theories that help better understand the physical mechanisms, it is often difficult to determine which local microscopic interactions shape and regulate self-organized structures in active particle systems. Using a combination of unsupervised clustering algorithms and sparsity-promoting inference, we learn from data dominant force balance laws that locally drive the emergence of macroscopic patterns in active particle systems. We consider a classic hydrodynamic model of self-propelled particle systems that hosts solutions composed of spatiotemporal patterns like asters and propagating stripes. We show that 1) propagating stripes are formed by local alignment interactions and driven by gradients in polarization density and 2) steady-state asters are shaped by a mechanism of splay-induced negative compressibility arising from strong particle interactions. These data-driven discoveries are in excellent agreement with analytical predictions. We therefore believe that the presented data-driven strategy, in combination with physical modeling, can help our mechanistic understanding of active material systems as well as the design of biomimetic materials.

Keywords: active particle systems; active hydrodynamics; data-driven modeling; dominant balance models

Related publications

  • Open Access Logo Lecture (Conference)
    9th GACM Colloquium on Computational Mechanics, 21.-23.09.2022, Essen, Germany
  • Open Access Logo Poster
    HZDR Doctoral Seminar 2022, 19.-21.10.2022, Wroclaw, Poland

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Permalink: https://www.hzdr.de/publications/Publ-34822
Publ.-Id: 34822


Convection triggers MRI amplitude and phase signal changes during proton beam irradiation of liquid water phantoms

Peter, J.; Gantz, S.; Karsch, L.; Pawelke, J.; Hoffmann, A. L.

In-beam MRI has recently proven capable of visualising proton beams in liquid-filled
phantoms based on beam-induced local MR signal amplitude loss. This holds promise for on-
line beam range verification and dosimetric as well as geometric quality assurance for hybrid
MRI-proton therapy systems currently under development. The purpose of this study was
firstly to determine whether, in addition to MR signal amplitude loss, the MRI phase signal is
affected by the proton beam and secondly, to test whether these changes in MRI signals are
triggered by beam-induced convection.

  • Contribution to proceedings
    13th interventional MRI symposium 2022, 14.-15.10.2022, Leipzig, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34821
Publ.-Id: 34821


Combined proton radiography and irradiation for high-precision preclinical studies in small animals

Schneider, M.; Elisabeth, B.; Suckert, T.; Beyreuther, E.; Bock, J.; Dietrich, A.; Gantz, S.; Heuchel, L.; Krause, M.; Neubeck, C. V.; Nexhipi, S.; Tillner, F.; Schürer, M.; Lühr, A.; Müller, J.

Background and purpose: Proton therapy has become a popular treatment modality in the field of radiooncology due to higher spatial dose conformity compared to conventional radiotherapy, which holds the potential to spare normal tissue. Nevertheless, unresolved research questions, such as the much debated relative biological effectiveness (RBE) of protons, call for preclinical research, especially regarding in vivo studies. To mimic clinical workflows, high-precision small animal irradiation setups with image-guidance are needed.

Material and methods: A preclinical experimental setup for small animal brain irradiation using proton radiographies was established to perform planning, repositioning, and irradiation of mice. The image quality of proton radiographies was optimized regarding the resolution, contrast-to-noise ratio (CNR), and minimal dose deposition in the animal. Subsequently, proof-of-concept histological analysis was conducted by staining for DNA double-strand breaks that were then correlated to the delivered dose.

Results: The developed setup and workflow allow precise brain irradiation with a lateral target positioning accuracy of <0.26mm for in vivo experiments at minimal imaging dose of <23mGy per mouse. The custom-made software for image registration enables the fast and precise animal positioning at the beam with low observer-variability. DNA damage staining validated the successful positioning and irradiation of the mouse hippocampus.

Conclusion: Proton radiography enables fast and effective high-precision lateral alignment of proton beam and target volume in mouse irradiation experiments with limited dose exposure. In the future, this will enable irradiation of larger animal cohorts as well as fractionated proton irradiation.

Keywords: Proton therapy; Proton radiography; Mouse brain irradiation; preclinical (in vivo) studies; DNA damage; Relative biological effectiveness (RBE)

Related publications

Permalink: https://www.hzdr.de/publications/Publ-34820
Publ.-Id: 34820


Flow Morphology of TEG Desiccant in a Structured Packing Air Dehumidifier Exposed to Floating Conditions

Mamedov, T.; Schleicher, E.; Schubert, M.; Ehlert, T.; Kenig, E. Y.; Hampel, U.

In this work, an approach is proposed to study the influence of floating conditions on the fluid flow behavior of separation columns. A structured packing (Mellapak 250Y) air dehumidifier was embarked on a hexapod ship motion emulator with six-degree-of-freedom motions to mimic swell. A novel flow imaging sensor has been developed to visualize the flow morphology dynamics of triethylene glycol evolving on the corrugated sheets of packings. Furthermore, a numerical model was developed based on the hydrodynamic analogy concept to evaluate the separation performance using experimentally observed flow patterns. In our contribution, we describe the flow imaging sensor design as well as the impact of tilt on efficiency losses in comparison with the conventional upright stationary column.

Keywords: Moving columns; Hydrodynamics; FPSO; Flow imaging sensor; HA approach

  • Contribution to proceedings
    The 12th international conference Distillation & Absorption 2022, 18.-21.09.2022, Toulouse, France

Permalink: https://www.hzdr.de/publications/Publ-34819
Publ.-Id: 34819


Liquid flow morphology investigation in structured packings for offshore applications using a novel flow imaging sensor

Mamedov, T.; Schleicher, E.; Schubert, M.; Ehlert, T.; Kenig, E. Y.; Hampel, U.

Environmental and economic constraints for oil and gas production necessitate the development of cost-effective operating facilities in the modern offshore industry. For this reason, floating production systems are increasingly used to operate oil and gas fields in deepwater locations, whereby high submarine pipeline expenditures of fixed offshore platforms are eliminated. Apart from economic advantages, floating production systems maintain a safe operation and continuous production under severe ocean conditions, i.e. cyclones, huge waves and floating icebergs. Whilst traditional fossil energy sources are continuously losing their dominance, liquefied natural gas (LNG) is gaining popularity in the energy market owing to the comparatively lower greenhouse gas emissions. For LNG production, Floating Production Storage and Offloading (FPSO) units combine the feature of onshore LNG plants and that of storage tankers in a single large marine vessel. Thus, the number of FPSOs for LNG production has been growing in the offshore industry. The design principles for land-based process units cannot be directly applied to FPSO topside equipment because of wind-generated wave effects. Separation columns are more susceptible to the motion impact than most of the onboard process equipment, and consequent product quality losses represent the main concern.
Separation columns with structured packings are mostly used on floating platforms due to their low pressure drop, high capacity and performance. To study the dynamics of the flow morphology in the packing and the corresponding mass transfer performance, a structured packing column is embarked on a hexapod motion simulator, which mimics the six-degree-of-freedom ship motion (cf. Fig. 1). The process of air dehumidification by triethylene glycol (TEG) solutions is used as an example. A novel flow imaging sensor was developed to visualize the flow morphology dynamics evolving on the corrugated sheets of the structured packing (Fig. 2). The sensor detects most relevant morphologies, i.e. unwetted, partially and fully wetted channels and their corresponding film thicknesses on the packing sheets for the tilted and moving column allowing a comparison with the vertically oriented configuration.
At a later step, along with the fluid dynamics, the separation performance of air dehumidification and the liquid desiccant regeneration processes will be evaluated. The experimental data will be used to develop a new modelling approach for floating structured packing columns based on hydrodynamic analogies between complex flow patterns in real columns and simplified fluid-dynamic elements.

  • Contribution to proceedings
    Jahrestreffen der ProcessNet-Fachgruppen Fluidverfahrenstechnik und Hochdruckverfahrenstechnik, 02.-03.05.2022, Frankfurt am Main, Deutschland
    Proceedings des Jahrestreffens der ProcessNet-Fachgruppen Fluidverfahrenstechnik und Hochdruckverfahrenstechnik
  • Poster
    Jahrestreffen der ProcessNet-Fachgruppen Fluidverfahrenstechnik und Hochdruckverfahrenstechnik, 02.-03.05.2022, Frankfurt am Main, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34818
Publ.-Id: 34818


Optimization and preliminary design of a high-temperature, low pressure-ratio sCO2-compressor for a wide operating range

Rath, S.; Unger, S.; Hampel, U.; Gampe, U.

Power cycles based on supercritical carbon dioxide (sCO2) promise higher thermal efficiencies and more compact components than conventional technologies. Within the CARBOSOLA project, funded by the German Federal Ministry for Economic Affairs and Energy, a large-scale experimental facility is being set up by a consortium of scientific and industrial partners to actively contribute to the development of sCO2 technology. The first expansion stage provides a circulation of the sCO2 flow without expansion devices in the test loop. Thereby the compressor is intended to compensate for pressure losses and consequently for low pressure differences. In addition to that, a preferably wide operating range, regarding temperature and pressure, shall provide a high degree of flexibility of the test rig.
This work presents the design optimization of the impeller aiming at a wide operating range in compliance with the boundary conditions set for the test rig and the use of sCO2. For this purpose, a hybrid approach is used, combining parametric three-dimensional modeling with a one-dimensional performance criterion for operating range estimation. A large number of impeller designs have been simulated numerically within an optimization procedure using a genetic algorithm. On this basis, several designs have been selected and compared against each other. The evaluation includes sets of performance lines and the validation of the one-dimensional criterion used for optimization.

  • Open Access Logo Contribution to proceedings
    7th International sCO2 Power Cycles Symposium, 21.-24.02.2022, San Antonio, Texas, USA
    Optimization and preliminary design of a high-temperature, low pressure-ratio sCO2-compressor for a wide operating range
  • Open Access Logo Poster
    Optimization and preliminary design of a high-temperature, low pressure-ratio sCO2-compressor for a wide operating range, 21.-24.02.2022, San Antonio, Texas, USA

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Permalink: https://www.hzdr.de/publications/Publ-34817
Publ.-Id: 34817


Comparative analysis of uranium(VI) reduction by a sulfate- and an iron-reducing bacterium

Hilpmann, S.; Jeschke, I.; Steudtner, R.; Hübner, R.; Stumpf, T.; Cherkouk, A.

The safe disposal of high-level radioactive waste represents a significant scientific and societal challenge. According to geological, geochemical, and geophysical properties, clay formations represent a suitable host rock for the long-term storage of this waste. However, for a comprehensive safety assessment, the influence of naturally occurring microorganisms in clay rock and in the backfill material bentonite must be taken into account.
Desulfosporosinus species play a crucial role in the community of sulfate-reducing bacteria present in clay rock and bentonite.[1,2] Desulfosporosinus hippei DSM 8344T is a close relative of the isolated species and was originally found in permafrost soils.[3] Desulfitobacterium sp. G1-2 has been isolated from bentonite samples and is an important representative of iron-reducing bacteria. As members of the microbial community from deep geological layers, these strains were selected to get a more profound knowledge about their interactions with U(VI).
During time-dependent experiments in bicarbonate buffer (30 mM, 100 µM U(VI)), Desulfitobacterium sp. G1-2 showed a removal of up to 80% within 5 days. UV/Vis studies of the dissolved cell pellets verified the formation of U(IV) during the process.
In contrast to these findings, Desulfosporosinus hippei DSM 8344T was not able to reduce U(VI) in the presence of bicarbonate. Therefore, experiments in artificial Opalinus Clay pore water [4] (100 µM U(VI), pH 5.5) were conducted. Determinations of the U concentrations showed a removal of up to 80% of the radionuclide from the supernatants within only 48 h. UV/Vis studies of the dissolved cell pellets provided clear proof of a partially reduction of U(VI) to U(IV), although bands of U(VI) were also still observable. These findings propose a combined association-reduction process as a possible interaction mechanism for this microorganism.
TEM images combined with EDX analysis revealed the presence of two different U-containing aggregates inside cells of Desulfitobacterium sp. G1-2. Furthermore, cells of Desulfosporosinus hippei DSM 8344T released membrane vesicles as a possible defense mechanism against encrustation by U precipitates on the cell surface. However, cells showed almost no uptake of U.
In this study, different analytical methods were used to better understand the U(VI) reduction by sulfate- and iron-reducing bacteria. Significant differences in the occurring mechanisms were evident between both microorganisms, highlighting the importance of studies on the U(VI) interactions of different microorganisms present in clay rock. Moreover, these results contribute to a safety concept for a nuclear repository in clay formations and for final disposal sites using bentonite as backfill material.

References:

[1] Bagnoud et al. (2016) Nat. Commun 7, 1–10.
[2] Matschiavelli et al. (2019) Environ. Sci. Technol. 53, 10514–10524.
[3] Vatsurina et al. (2008) Int. J. Syst. Evol. Microbiol. 58, 1228–1232.
[4] Wersin et al. (2011) Appl. Geochemistry 26, 931–953.

Keywords: Uranium(VI) reduction; Sulfate-reducing bacteria; Iron-reducing bacteria

  • Lecture (Conference)
    14th International Symposium on Nuclear and Environmental Radiochemical Analysis: ERA14, 12.-15.09.2022, York, Großbritannien

Permalink: https://www.hzdr.de/publications/Publ-34816
Publ.-Id: 34816


Simulation of particle resuspension by wind in an urban system

Banari, A.; Hertel, D.; Schlink, U.; Hampel, U.; Lecrivain, G.

Air pollution caused by particle resuspension is a growing public health problem in many cities. Pollen and anthropogenic pollutants, such as heavy metal particles and micro-plastics debris, settle onto urban ground surfaces. Prolonged urban heat waves are propitious for heavy and continuous deposition. Particles in the submillimeter size range eventually resuspend by urban winds within seconds, may be inhaled, cause allergic reactions and escape the city's boundaries. Here, the resuspension and subsequent dispersion of generic particles ranging from 10 to 100 μm in size are simulated. The city area “Bayerischer Bahnhof” in Leipzig, Germany, has been chosen as a practical example. To track the resuspended particles, a Lagrangian model is used. Taking advantage of graphics processing unit, turbulent flow simulations at different wind speeds are performed in almost real time. The results show that particle resuspension starts, when the inlet wind speed beyond the canopy, that is at a height of 40 m, exceeds 7 m/s. At wind speed beyond 14 m/s, resuspension occurs in almost all city parts. At moderate wind speed, high-risk areas are identified. The effect of green infrastructures on both the flow field and particle resuspension is also investigated.

Keywords: particle resuspension; Bayerischer Bahnhof; public health

Permalink: https://www.hzdr.de/publications/Publ-34815
Publ.-Id: 34815


Untersuchung der Innenströmung einer Taylorblase mit einem neuartigen PIV-System mit deformierbarem Spiegel

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

Aerosolpartikel liegen in nahezu allen Gasen vor. Die Abscheidung dieser Partikel ist unter anderem bei der Reinigung von Luft von Feinstaub und Viren relevant. Auch in der Verfahrenstechnik reagieren beispielsweise Gase mit Feststoffen, wie bei der Gasphasenpolymerisation. Für Partikel im Größenbereich von 0,1 – 10 µm sind bisher aufgrund zu weniger empirischer Daten keine zuverlässigen Vorhersagen der Prozesse möglich.
In diesem Beitrag werden Messungen der Innenströmung einer Blase in verschiedenen, mit Wasser durchströmten Rohren gezeigt. In einem Rohr mit konstantem Durchmesser ist ein langgezogener Wirbel sichtbar. Zur Beeinflussung der Blaseninnenströmung ist in einem Rohr eine Verjüngung eingebracht. Die Verjüngung erzeugt in der Blase einen zweiten Wirbel, welcher die gleiche Rotationsrichtung aufweist. Im Berührungsbereich zwischen beiden Wirbeln treffen entgegengesetzte Strömungen aufeinander.

  • Lecture (Conference)
    29. Fachtagung "Experimentelle Strömungsmechanik", 06.-08.09.2022, Ilmenau, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34814
Publ.-Id: 34814


XANES calculations of actinide-based materials

Amidani, L.; Kvashnina, K.

XANES, with its high sensitivity to the oxidation state and the local structure, is a very powerful tool to investigate actinide-based materials. The use of the High-Energy-Resolution Fluores-cence-Detected (HERFD) mode opened new perspective in this field. By reducing the core-hole lifetime broadening, HERFD allows a relevant gain in resolution at the L3 edge and a major im-provement for M4,5 edges.
The information contained in a XANES spectrum are often hard to extract and therefore need the support of theory. However, calculations of actinide materials made complex by the compa-rable strength of intra-electronic interactions, spin-orbit and influence of the local environment. Efforts are ongoing to take all the relevant physics into account, however today none of the the-oretical framework used in XANES calculations can account for all relevant interactions over a large cluster of atoms.
If we do not yet have a unique theoretical framework that can be applied to all actinide systems, we can still select the theory that is more adapted to specific cases. In this contribution we will present progresses in the interpretation of XANES of actinide systems obtained by using the DFT–based code FDMNES [1]. Results at the L3 and M4,5 edges on Th4+ and U6+ systems will be presented [2-4]. These systems, where the intra-electronic interactions are less relevant due to the absence of 5f valence electrons, are particularly suited to investigate the importance of the local environment on the spectral shape.
Our results endorse the use of HERFD XANES coupled with DFT-based calculations to investi-gate complex actinide-containing systems.

Related publications

  • Lecture (Conference)
    ATAS-AnXAS 2022 - joint workshop, 17.-21.10.2022, Grenoble, France

Permalink: https://www.hzdr.de/publications/Publ-34813
Publ.-Id: 34813


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