Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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42018 Publications

Pressure-transferable neural network models for density-functional theory

Callow, T. J.; Fiedler, L.; Modine, N.; Cangi, A.

Abstract

Density functional theory (DFT) is well-known as the workhorse of electronic structure calculations in materials science and quantum chemistry. However, its applications stretch beyond these traditionally-studied fields, such as to the warm-dense matter (WDM) regime. Under WDM conditions, there are different challenges to consider (compared to ambient conditions) when using DFT. Namely, the electronic structure problem must be solved (i) for large particle numbers, (ii) for a range of temperatures, and (iii) for a range of pressures. Promising solutions were demonstrated for problems (i) and (ii) [1,2] using a recently-developed workflow to machine-learn the local density of states (LDOS) [3]. In this talk, we discuss our progress in developing a solution for problem (iii). This problem presents additional challenges because the LDOS varies quite significantly with changes in the pressure, making it a difficult problem for neural network models.

[1] L Fiedler et al., npj Comput Mater 9, 115 (2023) [2] L Fiedler et al., Phys. Rev. B 108, 125146 (2023) [3] J. A. Ellis et al., Phys. Rev. B 104, 035120 (2021)

  • Lecture (Conference)
    87th Annual Conference of the DPG and DPG Spring Meeting, 17.-22.03.2024, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38892


Optimization of membraneless alkaline water electrolysis

Rox, H.; Gatter, J.; Frense, E.; Schoppmann, K.; Rüdiger, F.; Krause, L.; Yang, X.; Mutschke, G.; Fröhlich, J.; Eckert, K.

Abstract

Objectives
Membraneless alkaline electrolyzer (MAEL) allow higher current densities compared to conventional designs [1] and provide very good access to the electrodes, making them ideal for research to better understand bubble formation and detachment.

Methods
In the present study both elements of a MAEL, porous electrodes and cell geometry, are optimized individually. For the geometrical optimization, CFD and current simulations were performed to obtain an optimized cell geometry that ensures constant conditions for the water splitting reaction over the entire electrode area. A three-electrode cell was used to perform parametric studies of HER on porous electrodes [2] and functionalized surfaces [3]. Therefore, Particle Image Velocimetry and Shadowgraphy were used to systematically study the influence of the electrode surface and the electrolyte flow as driving force for an effective H2 and O2 separation in a MAEL.

Results & Conclusions
It is shown that below a critical Recrit the evolving bubbles are stuck on the porous electrodes and lead to a blockage of the electrochemical active sites and to an increase of the cell potential. At the optimal flow rate to current density ratio high gas purity and overall efficiency were observed. Importantly, this study presented an experimental framework that guides the electrode and cell design of MAELs and analyzes their performance limits.

Literature
[1] D.V. Esposito, Joule. 2017, 1, 651-658.
[2] H. Rox et al., Int. J. Hydrog. Energy. 2023, 48, 2892-2905.
[3] L. Krause et al., ACS Applied Materials & Interfaces. 2023, 15, 14, 18290-18299.

Keywords: Alkaline electrolysis; Membraneless electrolyzer; Bubble dynamics; Shadowgraphy; PIV

Involved research facilities

  • Data Center
  • Lecture (Conference)
    HydrogenDays 2024, 21.03.2024, Prague, Czech republic

Permalink: https://www.hzdr.de/publications/Publ-38888


Towards tailoring hydrophobic interaction with uranyl(VI) oxygen for C-H activation

Tsushima, S.; Kretzschmar, J.; Doi, H.; Okuwaki, K.; Kaneko, M.; Mochizuki, Y.; Takao, K.

Abstract

Bovine serum albumin (BSA) has a uranyl(VI) binding hotspot where uranium is tightly bound by three carboxylates. Uranyl oxygen is “soaked” into the hydrophobic core of BSA. Isopropyl hydrogen of Val is trapped near UO22+ and upon photoexcitation, C–H bond cleavage is initiated. A unique hydrophobic contact with “yl”-oxygen, as observed here, can be used to induce C-H activation.

Permalink: https://www.hzdr.de/publications/Publ-38885


Optimization of Heat and Mass Transfer via Nano/Micro-Structured Surfaces: utilizing energy barriers between states and “semi-dimensional reduction”

Ding, W.; Zhang, J.; Zhao, P.; Reinecke, S.; Hampel, U.

Abstract

Energy barriers inhibit the transition of a system from one state to another. This is evident in phenomena such as bubble nucleation during boiling, droplet expansion and contraction when it impacts a heated surface, and also cavitation. In this presentation, we will elucidate our insights and understanding of the exploitation of energy barriers post-state transition to augment heat and mass transfer in various processes. Specifically, in processes like bubble nucleation in boiling, the high energy required for nucleation (attributable to the energy barrier) triggers rapid bubble expansion and results in a semi-2D microlayer, just a few micrometers thin, on the surface. This can be viewed as a typical semi-dimensional reduction effect, transitioning a part of system from 3D to 2D. As a result, this thin liquid layer brings high efficiency on heat transfer. A similar phenomenon occurs when a droplet impacts a heated surface. Following impact, the droplet’s expansion and contraction on the surface incite capillary waves that propagate along the droplet interface, inducing a semi-1D, prickle-like jet along the droplet’s axis on the top side. This jet disrupts the vapor film beneath the droplet, expelling the vapor and delaying the Leidenfrost point. As a one more thing, cavitation, one of the most typical cases of ‘dimensional reduction’, utilizes a reduction from 3D to 0D and also the large energy barrier for bubble nucleation. Following bubble collapse, the local temperature and pressure reach 5000 K and ~ Mpa, respectively. Combined with O3, this effect facilitates a highly efficient oxidation process.

  • Invited lecture (Conferences)
    4th Conference on Micro FLow and Interfactial Phenomena (µFIP) 2024, 21.-24.06.2024, The Hong Kong Polytechnic University, HongKong, China

Permalink: https://www.hzdr.de/publications/Publ-38883


Applying an Explicit Temperature-dependent Generalized Gradient Approximation to Warm Dense Matter: Thermal PBE

Ramakrishna, K.; Lokamani, M.; Cangi, A.

Abstract

Using the methodology of Kozlowski et al. [arXiv 2308.03319 (2023)] to extend the temperature dependence of the Perdew–Burke–Ernzerhof (PBE) generalized gradient approximation, we implement the thermal equivalent of the PBE functional (tPBE) in a plane wave code to study the equilibrium properties such as energies, pressures, and forces of warm dense matter using density functional theory and linear-response properties such as the electrical conductivity, dynamic structure factor using time-dependent density functional theory. In addition, we compare the effects with the thermal equivalent of LDA and the ground-state LDA and PBE functionals.

Keywords: Density functional theory; Matter under Extreme Conditions

  • Lecture (Conference)
    APS March Meeting 2024, 04.-08.03.2024, Minneapolis, USA

Permalink: https://www.hzdr.de/publications/Publ-38880


Structure prediction of iron hydrides across pressure range with transferable machine-learned interatomic potential

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

Abstract

Recently, machine-learned interatomic potentials (ML-IAPs) have emerged as a solution to the computational limitations of density functional theory (DFT)-based approaches, enabling the modeling of large systems with hundreds or even thousands of atoms. Here, we demonstrate the efficacy of automated and systematic methods for training and validating transferable ML-IAPs through global optimization techniques.

We utilize the PyFLAME code [1] to construct a highly transferable neural network potential. With this accurate and fast potential, we systematically investigate the potential energy surfaces (PESs) of FeH through global sampling using the minima hopping method [2] over a wide range of pressures. This comprehensive exploration enables us to predict stable and metastable iron hydrides from 0 to 100 GPa.

Our analysis reveals the experimentally observed global minimum structures -the dhcp, hcp, and fcc phases- in agreement with previous studies. Furthermore, our exploration of the PESs of FeH at various pressures uncovers numerous interesting modifications and stacking faults of the aforementioned phases, including several remarkably low-enthalpy structures.

This investigation led to the discovery of a rich array of novel stoichiometric crystal phases of FeH across a wide pressure range, confirming the presence of coexisting regions containing known FeH structures. This finding demonstrates one of the benefits of using large-scale structure prediction techniques to uncover the PESs of materials.

[1] H. Mirhosseini, H. Tahmasbi, S. R. Kuchana, S. A. Ghasemi, and T. D. Kühne, Comput. Mater. Sci. 197, 110567 (2021).

[2] M. Amsler and S. Goedecker, J. Chem. Phys. 133, 224104 (2010).

  • Open Access Logo Lecture (Conference)
    APS MArch meeting 2024, 04.-08.03.2024, Minneapolis, US

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Permalink: https://www.hzdr.de/publications/Publ-38878


Live Iterative Ptychography

Weber, D.; Ehrig, S.; Schropp, A.; Clausen, A.; Achilles, S.; Hoffmann, N.; Bussmann, M.; Dunin-Borkowski, R.; Schroer, C. G.

Abstract

We demonstrate live-updating ptychographic reconstruction with ePIE, an iterative ptychography method, during ongoing data acquisition. The reconstruction starts with a small subset of the total data, and as the acquisition proceeds the data used for reconstruction is extended. This creates a live-updating view of object and illumination that allows monitoring the ongoing experiment and adjusting parameters with quick turn-around. This is particularly advantageous for long-running acquisitions. We show that such a gradual reconstruction yields interpretable results already with a small subset of the data. We show simulated live processing with various scan patterns, parallelized reconstruction, and real-world live processing at the hard X-ray ptychographic nanoanalytical microscope PtyNAMi at the PETRA III beamline.

Keywords: ptychography; X-ray microscopy

Permalink: https://www.hzdr.de/publications/Publ-38877


Effect of Ba(II), Eu(III), and U(VI) on rat NRK-52E and human HEK-293 kidney cells in vitro

Senwitz, C.; Butscher, D.; Holtmann, L.; Vogel, M.; Steudtner, R.; Drobot, B.; Stumpf, T.; Barkleit, A.; Heller, A.

Abstract

Heavy metals pose a potential health risk to humans when they enter the organism. Renal excretion is one of the elimination pathways and, therefore, investigations with kidney cells are of particular interest. In the present study, the effects of Ba(II), Eu(III), and U(VI) on rat and human renal cells were investigated in vitro. A combination of microscopic, biochemical, analytical, and spectroscopic methods was used to assess cell viability, cell death mechanisms, and intracellular metal uptake of exposed cells as well as metal speciation in cell culture medium and inside cells.

For Eu(III) and U(VI), cytotoxicity and intracellular uptake are positively correlated and depend on concentration and exposure time. An enhanced apoptosis occurs upon Eu(III) exposure whereas U(VI) exposure leads to enhanced apoptosis and (secondary) necrosis. In contrast to that, Ba(II) exhibits no cytotoxic effect at all and its intracellular uptake is time-independently very low. In general, both cell lines give similar results with rat cells being more sensitive than human cells.

The dominant binding motifs of Eu(III) in cell culture medium as well as cell suspensions are (organo-) phosphate groups. Additionally, a protein complex is formed in medium at low Eu(III) concentration. In contrast, U(VI) forms a carbonate complex in cell culture medium as well as each one phosphate and carbonate complex in cell suspensions. Using chemical microscopy, Eu(III) was localized in granular, vesicular compartments near the nucleus and the intracellular Eu(III) species equals the one in cell suspensions.

Overall, this study contributes to a better understanding of the interactions of Ba(II), Eu(III), and U(VI) on a cellular and molecular level. Since Ba(II) and Eu(III) serve as inactive analogs of the radioactive Ra(II) and Am(III)/Cm(III), the results of this study are also of importance for the health risk assessment of these radionuclides.

Keywords: Cytotoxicity; Radionuclides; Kidney cells; Heavy metal speciation; TRLFS; Chemical microscopy

Permalink: https://www.hzdr.de/publications/Publ-38876


Electrical characterization of multi‑gated WSe2/MoS2 van der Waals heterojunctions

Chava, P.; Kateel, V.; Watanabe, K.; Taniguchi, T.; Helm, M.; Mikolajick, T.; Erbe, A.

Abstract

Vertical stacking of different two-dimensional (2D) materials into van der Waals heterostructures exploits the properties of individual materials as well as their interlayer coupling, thereby exhibiting unique electrical and optical properties. Here, we study and investigate a system consisting entirely of different 2D materials for the implementation of electronic devices that are based on quantum mechanical band-to-band tunneling transport such as tunnel diodes and tunnel field-effect transistors. We fabricated and characterized van der Waals heterojunctions based on semiconducting layers of WSe2 and MoS2 by employing different gate configurations to analyze the transport properties of the junction. We found that the device dielectric environment is crucial for achieving tunneling transport across the heterojunction by replacing thick oxide dielectrics with thin layers of hexagonal boronnitride. With the help of additional top gates implemented in different regions of our heterojunction device, it was seen that the tunneling properties as well as the Schottky barriers at the contact interfaces could be tuned efficiently by using layers of graphene as an intermediate contact material.

Keywords: 2d material; van der waals; heterostructure; tunneling; transistor

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Permalink: https://www.hzdr.de/publications/Publ-38872


Dynamics of particle attachment in a model stirred cell: A new technique to characterize and quantify particle floatability

Eftekhari, M.; Schwarzenberger, K.; Schlereth, P.; Eckert, K.

Abstract

Floatability evaluation is critical to predicting flotation results and designing a flotation flowsheet. Laboratory-scale flotation cells are commonly used to study particle floatability, but differences in cell design and governing hydrodynamics make extrapolation to industrial scale operations difficult.
In this work, a new experimental approach based on particle attachment dynamics is proposed to evaluate particle floatability. This method allows precise control of hydrodynamic conditions, visualization of attachment processes, and direct observation of the bubble surfaces. It is therefore ideal for studying attachment dynamics as a function of collector concentration, particle size and concentration, and propeller speed. In addition, it opens the possibility for future studies of the packing density of the particles at the interface and their selective attachment. By evaluating the time-dependent surface coverage as a function of bubble residence time, we illustrate its ability to predict flotation kinetics within a flotation cell. This innovative technique provides a faster, more versatile means of studying particle floatability and attachment dynamics with practical implications for flotation cell optimization.

Keywords: Floatability; Stirred cell; Particle-bubble interactions; Dynamic surface coverage; Flotation kinetics

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Permalink: https://www.hzdr.de/publications/Publ-38871


Recent extensions to the NUSAR-RCS IT environment

Lehnigk, R.; Hänsch, S.; Schlegel, F.; Lucas, D.

Abstract

Due to the growing importance of Computational Fluid Dynamics (CFD) for reactor safety research, there have been activities aimed at qualifying the associated methods for many years. This entails the development and validation of models on the basis of detailed experimental data, generated in comprehensive projects. There was and is a need for development, among other things, for multiphase flows, in particular for accident scenarios in the reactor coolant system. In order to be able to use the model developments and validation data generated throughout various publicly funded projects in the long term, these are carried out using the software provided by the OpenFOAM Foundation, which is thereby qualified for application. The project presented here is funded by the German Federal Ministry for Environment, Nature Conservation, Nuclear Safety and Consumer Protection (project number 1501658) and has the objective of gathering and maintaining addon software and simulation setups from partner institutions in a common repository, referred to as "Nuclear Safety Repository for OpenFOAM Foundation Software for Reactor Cooling System (NUSAR-RCS)". To this end, a GitLab-based IT environment has been developed that fosters collaborative developments and facilitates the maintenance of results from completed projects. The talk will highlight some recent additions to the environment. The first part is dedicated to a Python package, which, among other things, supplies functionality for bulk processing of simulation results, e.g. to extract global information on the agreement between simulation and experiment using statistical key figures. The second part will present efforts of making the NUSAR-RCS software more portable by means of containerization using Apptainer images.

  • Lecture (Conference)
    35th German CFD Network of Competence Meeting, 12.-13.03.2024, München, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38870


Microstructural Investigation of Au Ion-Irradiated Eu-Doped LaPO4 Ceramics and Single Crystals

Gilson, S.; Svitlyk, V.; Bukaemskiy, A. A.; Niessen, J.; Lender, T.; Murphy, G. L.; Henkes, M.; Lippold, H.; Marquardt, J.; Akhmadaliev, S.; Hennig, C.; Winkler, B.; Tonnesen, T.; Peters, L.; Fischer, C.; Huittinen, N. M.

Abstract

To mimic radiation damage by recoiling nuclei following alpha-decay, ceramics and single crystals of LaPO4 monazite doped with Eu(III) were irradiated with 14 MeV Au5+ ions at three different fluences. The crystallinity, local coordination environments, and topography of the samples were probed using numerous methods including grazing-incidence X-ray diffraction (GIXRD), vertical scanning interferometry (VSI), scanning electron microscopy (SEM), Raman, and luminescence spectroscopy. GIXRD data collected from the irradiated regions of the ceramics revealed fluence dependent amorphization. A similar level of amorphization was detected for samples irradiated with 5×1013 ions/cm2 (fluence, F1) and 1×1014 ions/cm2 (F2), while a slightly lower contribution to the scattering signal from the amorphous part was obtained for the sample irradiated with the highest fluence of 1×1015 ions/cm2 (F3). VSI showed clear swelling of entire grains at the highest ion fluence, while more localized damage to grain boundaries was detected for ceramic samples irradiated at the lowest fluence. Single crystal specimens showed no pronounced topography changes following irradiation. SEM backscattered electron images revealed that the ceramic irradiated at the highest fluence exhibited topological features indicative of grain surface melting or softening and displacement of grains. Finally, Raman and luminescence data showed a different degree of disorder in polycrystalline vs. single crystal samples. While changes to PO4 stretching and bending vibrations could be observed in the ceramics, these changes were more subtle or not present in the single crystals. The opposite was observed when probing the local Ln-O environment using Eu(III) luminescence, where the larger changes in terms of an elongation of the Eu-O (or La-O) bond and an increasing relative disorder with increasing fluence were observed only for the single crystals. The dissimilar trends observed in irradiated single crystals and ceramics indicate that grain boundary chemistry likely plays a significant role in the radiation response.

Keywords: ion irradiation; damage; monazite; Raman; luminescence; grazing incidence diffraction; vertical scanning interferometry; scanning electron microscopy

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-38869


On the relevance of lift force modelling in turbulent wall flows with small inertial particles

Gao, W.; Shi, P.; Parsani, M.; Costa, P.

Abstract

In particle-laden turbulent wall flows, lift forces can influence near-wall turbulence. This has been recently observed in particle-resolved simulations, which, however, are too expensive to be used in upscaled models. Instead, point-particle simulations have been the method of choice to simulate the dynamics of these flows during the last decades. While this approach is simpler, cheaper, and physically sound for small inertial particles in turbulence, some issues remain. In the present work, we address challenges associated with lift force modelling in turbulent wall flows and the impact of particle lift forces in the near-wall flow. We performed direct numerical simulations (DNS) of small inertial point particles in turbulent channel flow for fixed Stokes number and mass loading while varying the particle size. Our results show that the particle dynamics in the buffer region, causing the apparent particle-to-fluid slip velocity to vanish, raise major challenges for accurately modelling lift forces. While our results confirm that lift forces have little influence on particle dynamics for sufficiently small particle sizes, for inner-scaled diameters of order one and beyond, lift forces become quite important near the wall. The different particle dynamics under lift forces result in the modulation of streamwise momentum transport in the near-wall region. We analyze this lift-induced turbulence modulation for different lift force models, and the results indicate that realistic models are critical for particle-modeled simulations to correctly predict turbulence modulation by particles in the near-wall region.

Keywords: particle-laden wall turbulence; lift force; turbulence modulation

Permalink: https://www.hzdr.de/publications/Publ-38867


Repulsive Tomonaga-Luttinger liquid in the quasi-one-dimensional alternating spin-1/2 antiferromagnet NaVOPO4

Islam, S. S.; Mukharjee, P. K.; Biswas, P. K.; Telling, M.; Skourski, Y.; Ranjith, K. M.; Baenitz, M.; Inagaki, Y.; Furukawa, Y.; Tsirlin, A. A.; Nath, R.

Abstract

We probe the magnetic field-induced Tomonaga-Luttinger liquid (TLL) state in the bond-alternating spin-1/2 antiferromagnetic (AFM) chain compound NaVOPO4 using thermodynamic as well as local μSR and 31P NMR probes down to mK temperatures in magnetic fields up to 14 T. The μSR and NMR relaxation rates in the gapless TLL regime decay slowly following characteristic power-law behavior, enabling us to directly determine the interaction parameter K as a function of the magnetic field. These estimates are crosschecked using magnetization and specific heat data. The field-dependent K lies in the range of 0.4 < K < 1 and indicates the repulsive nature of interactions between the spinless fermions, in line with the theoretical predictions. This renders NaVOPO4 the first experimental realization of TLL with repulsive fermionic interactions in hitherto studied S = 1/2 bond-alternating AFM-AFM chain compounds.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

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Permalink: https://www.hzdr.de/publications/Publ-38863


Field-induced magnetic transitions in the highly anisotropic ferrimagnet ErFe5Al7 studied by high-field x-ray magnetic dichroism

Yamamoto, S.; Gorbunov, D.; Prokhnenko, O.; Weschke, E.; Miyata, A.; Diaz-Ortega, I. F.; Strohm, C.; Duc, F.; Henriques, M. S.; Gazizulina, A.; Uhlarz, M.; Mathon, O.; Andreev, A. V.; Nojiri, H.; Wosnitza, J.

Abstract

We present a comprehensive study of the magnetic properties of the strongly anisotropic ferrimagnet ErFe5Al7 in pulsed magnetic fields up to 30 T applied along the hard magnetization axis within the basal plane of the tetragonal lattice around the compensation temperature (Tcomp). Macroscopic measurements showed two anomalies at about 8 T and 25 T in a small temperature range around Tcomp. High-field x-ray magnetic circular dichroism (XMCD) data at the Er M5- and the Fe L3-edge resonances provide insight into the element-selective magnetization processes, revealing a coherent rotation of Er 4f and Fe 3d moments, with stepwise jumps including an unexpected one from an easy to a hard magnetization axis. XMCD at the Er L3-edge resonance elucidates the role of Er 5d electrons in coupling the Er 4f and the Fe 3d moments. Finally, an in-plane anisotropy constant was evaluated from a simulation of the magnetization process at temperatures well below Tcomp using a two-sublattice model.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

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  • Secondary publication expected from 05.03.2025

Permalink: https://www.hzdr.de/publications/Publ-38862


Pressure-tuned quantum criticality in the large-D antiferromagnet DTN

Povarov, K.; Graf, D. E.; Hauspurg, A.; Zherlitsyn, S.; Wosnitza, J.; Sakurai, T.; Ohta, H.; Kimura, S.; Nojiri, H.; Garlea, V. O.; Zheludev, A.; Paduan-Filho, A.; Nicklas, M.; Zvyagin, S.

Abstract

Strongly correlated spin systems can be driven to quantum critical points via various routes. In particular, gapped quantum antiferromagnets can undergo phase transitions into a magnetically ordered state with applied pressure or magnetic field, acting as tuning parameters. These transitions are characterized by z = 1 or z = 2 dynamical critical exponents, determined by the linear and quadratic low-energy dispersion of spin excitations, respectively. Employing high-frequency susceptibility and ultrasound techniques,we demonstrate that the tetragonal easy-plane quantum antiferromagnet NiCl2 ⋅ 4SC(NH2)2 (aka DTN) undergoes a spin-gap closure transition at about 4.2 kbar, resulting in a pressure-induced magnetic ordering. The studies are complemented by high-pressure electron-spin-resonance measurements confirming the proposed scenario. Powder neutron diffraction measurements revealed that no lattice distortion occurs at this pressure and the high spin symmetry is preserved, establishing DTN as a perfect platform to investigate z = 1 quantum critical phenomena. The experimental observations are supported by DMRG calculations, allowing us to quantitatively describe the pressure-driven evolution of critical fields and spin-Hamiltonian parameters in DTN.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

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Permalink: https://www.hzdr.de/publications/Publ-38861


Data publication: A deep-learning-based surrogate model for Monte-Carlo simulations of the linear energy transfer in primary brain tumor patients treated with proton-beam radiotherapy

Starke, S.; Kieslich, A. M.; Palkowitsch, M.; Hennings, F.; Troost, E. G. C.; Krause, M.; Bensberg, J.; Hahn, C.; Heinzelmann, F.; Bäumer, C.; Lühr, A.; Timmermann, B.; Löck, S.

Abstract

This repository contains the outputs and result data of our deep-learning-based experiments for the approximation of Monte-Carlo-simulated linear energy transfer distributions, which build the foundation for the corresponding article.

The Pytorch checkpoint of our finally chosen SegResNet architecture trained on the UPTD dose distributions is located at dd_pbs/Dose-LETd/clip_let_below_0.04/segresnet/all_trainvalid_data/training/lightning_logs/version_6358843/checkpoints/last.ckpt.

Moreover, we provide an exemplary data sample from a water phantom for trying our analysis pipeline.

Update:

In this new version we added results of the gamma analyses and the results obtained when trained on the same data as the above model with the difference that we did not clip Monte-Carlo-simulated LET maps as requested during the review process.

Keywords: proton-beam therapy; relative biological effectiveness; linear energy transfer; NTCP models; deep learning; brain tumor

Involved research facilities

  • OncoRay

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Permalink: https://www.hzdr.de/publications/Publ-38860


A deep-learning-based surrogate model for Monte-Carlo simulations of the linear energy transfer in primary brain tumor patients treated with proton-beam radiotherapy

Starke, S.; Kieslich, A. M.; Palkowitsch, M.; Hennings, F.; Troost, E. G. C.; Krause, M.; Bensberg, J.; Hahn, C.; Heinzelmann, F.; Bäumer, C.; Lühr, A.; Timmermann, B.; Löck, S.

Abstract

Objective: Neglecting variability in the relative biological effectiveness (RBE) in proton-beam therapy might result in unexpected side effects. Current research has indicated that the RBE is tightly associated with the dose-averaged linear energy transfer (LETd) of protons. Monte-Carlo (MC) simulations are currently considered the gold standard for LETd computations, but are computationally intensive and require exact models of the beam delivery device. We therefore explore whether neural networks (NNs) can serve as surrogate models of MC simulations for an accurate prediction of LETd based on the planned dose distribution and patient anatomy in the form of computed tomography (CT) images. Additionally, we evaluate the implications of using these NN models on established normal tissue complication probability (NTCP) models within a variable-RBE context.

Approach: The predictive performance of three-dimensional NN architectures was evaluated using five-fold cross-validation on a large cohort of brain tumor patients (n=151). The best-performing model was identified and externally validated on patients from a different center (n=107). LETd predictions were compared to MC-simulated results in various clinically relevant regions of interest. Furthermore, we assessed the impact on normal tissue complication probability (NTCP) models by leveraging LETd predictions to derive RBE-weighted doses, using an established variable-RBE model (Wedenberg).

Main results: We externally validated that NNs are able to approximate MC-based LETd maps solely based on the planned dose profile. Voxelwise root-mean-squared errors (RMSE) for the median LETd within the brain, brainstem, CTV, chiasm, lacrimal glands (ipsilateral/contralateral) and optic nerves (ipsilateral/contralateral) were 0.32, 0.83, 0.31, 0.71, 0.67, 1.00, 0.86 and 1.19 keV/µm, respectively. Although model predictions showed statistically significant differences from MC outputs, these did not translate to substantial changes in NTCP predictions, with RMSEs of at most 3.2%.

Significance: The ability of NNs to predict LETd based solely on planned dose profiles suggests a viable alternative to the compute-intensive MC simulations in a variable-RBE setting. This is particularly useful in scenarios where MC simulation data is unavailable, facilitating resource-constrained proton therapy treatment planning, retrospective patient data analysis and further investigations on the variability of proton RBE.

Keywords: proton-beam therapy; relative biological effectiveness; linear energy transfer; NTCP models; deep learning; brain tumor

Involved research facilities

  • OncoRay

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Permalink: https://www.hzdr.de/publications/Publ-38858


Diffuse glioma molecular profiling with Arterial Spin Labeling and Dynamic Susceptibility Contrast perfusion MRI: a comparative study

Prysiazhniuk, Y.; Server, A.; Leske, H.; Bech-Aase, Ø.; Helseth, E.; Sjouke Eijgelaar, R.; Fuster-García, E.; Brandal, P.; Bjørnerud, A.; Otáhal, J.; Petr, J.; Nordhøy, W.

Abstract

Background: Evaluation of molecular markers (IDH, pTERT, 1p/19q co-deletion, and MGMT) in adult diffuse gliomas is crucial for accurate diagnosis and optimal treatment planning. Dynamic Susceptibility Contrast (DSC) and Arterial Spin Labeling (ASL) perfusion MRI techniques have both shown good performance in predicting molecular markers, however, their performance has not been compared side-by-side.
Methods: Pre-treatment MRI data from ninety patients diagnosed with diffuse glioma (54 men/36 female, 53.1 ± 15.5 years) were retrospectively analyzed. DSC-derived normalized cerebral blood flow/volume (nCBF/nCBV) and ASL-derived nCBF in tumor and perifocal edema were analyzed in patients with available IDH–mutation (n=67), pTERT–mutation (n=39), 1p/19q co-deletion (n=33), and MGMT promoter methylation (n=31) status. Cross-validated uni- and multivariate logistic regression models assessed perfusion parameters’ performance in molecular marker detection.
Results: ASL and DSC perfusion parameters in tumor and edema distinguished IDH-wildtype (wt) and pTERT-wt tumors from mutated ones. Univariate classification performance was comparable for ASL-nCBF and DSC-nCBV in IDH (maximum AUROCC 0.82 and 0.83, respectively) and pTERT (maximum AUROCC 0.70 and 0.81, respectively) status prediction. The multivariate approach improved IDH (DSC-nCBV AUROCC 0.89) and pTERT (ASL-nCBF AUROCC 0.8, DSC-nCBV AUROCC 0.86) classification. However, ASL and DSC parameters could not differentiate 1p/19q co-deletion or MGMT promoter methylation status. Positive correlations were found between ASL-nCBF and DSC-nCBV/-nCBF in tumor and edema.
Conclusions: ASL is a viable gadolinium-free replacement for DSC for molecular characterization of adult diffuse gliomas.

Involved research facilities

  • PET-Center

Permalink: https://www.hzdr.de/publications/Publ-38857


A guide to advanced MRI processing for clinical glioma research

Clement, P.; Beun, S.; Arzanforoosh, F.; Castellaro, M.; Debiasi, G.; Emblem, K. E.; Fuster-Garcia, E.; Grech-Sollars, M.; Kallehauge, J. F.; Lazen, P.; Nunes, R. G.; Ozturk-Isik, E.; Pinto, J.; Piskin, S.; Robinson, S. D.; Siugzdaite, R.; Sollmann, N.; Fløgstad Svensson, S.; Warnert, E. A. H.; Wiegers, E.; Petr, J.; Hangel, G.

Abstract

Todate,multipleadvancedmagneticresonanceimaging(MRI)methodsbeyondconventionalqualitativestructuralimagingforthediagnosis,prognosis,andtreatmentfollow-upofgliomahavedemonstratedtheirutilityforclinicalstudies.However,thesemethodsoftenrelyoncomplexoff-scannerprocessingtoyieldthemostinformationandtoextractquantitativebiomarkers,limitingtheirpracticaluseforstudies,aswellastheirclinicaltranslation.Whilecommunity-drivensoftwaresolutionsexistfortheseadvancedMRImethods,manyaspiringclinicalresearchersfacechallengesinacquiringthenecessaryknowledgetoeffectivelyapplythesetools.Thisguide,aninitiativeoftheGliomaMRimaging2.0network(GliMR),aimstoprovideanoverviewofexistingsolutions,communities,andrepositorieswiththeultimategoalofenablingstandardization,openscience,andreproduciblequantitativeimagingstudiesofgliomas.Yet,mostofthereviewedtoolsandapproachestoimagedataanalysesmayalsobeusedinthecontextofstudiesondiseasesotherthanglioma.

Involved research facilities

  • PET-Center

Permalink: https://www.hzdr.de/publications/Publ-38856


NuScale SLB analysis with TrioCFD/ATHLET/DYN3D

Grahn, A.; Diaz Pescador, E.; Bilodid, Y.; Kliem, S.

Abstract

The small modular reactor (SMR) NuScale has been modelled in the framework of the EURATOM McSAFER project. The main objective was to demonstrate the feasibility of a coupled approach using a thermal-hydraulic system code (ATHLET), a 3-D reactor dynamics code (DYN3D) and a CFD software (TrioCFD) to model the whole primary coolant loop and large parts of the secondary side of the plant, including the downcomer-integrated, helical-coiled steam generators (SG) and the decay heat removal system (DHRS). The 3-D neutronic calculation of the reactor core was performed with a cross-section library developed with Serpent, and the coolant flow in the downcomer and lower plenum of the pressure vessel was analyzed by CFD. A double-ended, non-isolatable steam line break sequence served as a test case for the code coupling. Simulation results at steady-state show agreement with the reference values from the Design certification Application (DCA) report. The transient simulation shows that the rapid depressurization and boil-off with high steam rates towards the break lead to enhanced primary-to-secondary heat removal. However, the symmetrical arrangement of SGs in the NuScale reactor limits the coolant temperature reduction at the core inlet to prevent a possible power excursion which highlights the inherent safety of this reactor design.

Keywords: small modular reactors; steam line break; thermal-hydraulics; reactor dynamics; system codes; computational fluid dynamics

  • Lecture (Conference)
    Workshop on Core and Plant Simulation with an Emphasis on Fuel Behaviour in Light Water Reactor based Small Modular Reactors, 27.-29.02.2024, Wien, Österreich

Permalink: https://www.hzdr.de/publications/Publ-38855


Strain-modulated defect engineering of two-dimensional materials

Santra, P.; Ghaderzadeh, S.; Ghorbani Asl, M.; Komsa, H.-P.; Besley, E.; Krasheninnikov, A.

Abstract

Strain- and defect-engineering are two powerful approaches to tailor the opto-electronic properties of two-dimensional (2D) materials, but the relationship between applied mechanical strain and behavior of defects in these systems remains elusive. Using first-principles calculations, we study the response to external strain of $h$-BN, graphene, MoSe$_2$, and phosphorene, four archetypal 2D materials, which contain substitutional impurities. We find that the formation energy of the defect structures can either increase or decrease with bi-axial strain, depending on the atomic radius of the impurity atom, which can be larger or smaller than that of the host atom. Analysis of the strain maps indicates that this behaviour is associated with the compressive or tensile local strains produced by the impurities that interfere with the external strain. We further show that the change in the defect formation energy is related to the change in elastic moduli of the 2D materials upon introduction of impurity, which can correspondingly increase or decrease. The discovered trends are consistent across all studied 2D materials and are likely to be general. Our findings open up opportunities for combined strain- and defect-engineering to tailor the opto-electronic properties of 2D materials, and specifically, the location and properties of single-photon emitters.

Keywords: defects; strain; 2D materials; first-principles calculations

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-38854


Developing blood-brain barrier arterial spin labelling as a non-invasive early biomarker of Alzheimer’s disease (DEBBIE-AD): a prospective observational multicohort study protocol

Padrela, B.; Mahroo, A.; Tee, M.; Sneve, M. H.; Moyaert, P.; Geier, O.; Kuijer, J. P. A.; Beun, S.; Nordhøy, W.; David Zhu, Y.; Buck, M. A.; Hoinkiss, D. C.; Konstandin, S.; Huber, J.; Wiersinga, J.; Rikken, R.; de Leeuw, D.; Grydeland, H.; Tippett, L.; Cawston, E. E.; Ozturk-Isik, E.; Linn, J.; Brandt, M.; Tijms, B. M.; van de Giessen, E. M.; Muller, M.; Fjell, A.; Walhovd, K.; Bjørnerud, A.; Pålhaugen, L.; Selnes, P.; Clement, P.; Achten, E.; Anazodo, U.; Barkhof, F.; Hilal, S.; Fladby, T.; Eickel, K.; Morgan, C.; Thomas, D. L.; Petr, J.; Günther, M.; Mutsaerts, H. J. M. M.

Abstract

Introduction Loss of blood-brain barrier (BBB) integrity is
hypothesised to be one of the earliest microvascular signs
of Alzheimer’s disease (AD). Existing BBB integrity imaging
methods involve contrast agents or ionising radiation, and
pose limitations in terms of cost and logistics. Arterial
spin labelling (ASL) perfusion MRI has been recently
adapted to map the BBB permeability non-invasively. The
DEveloping BBB-ASL as a non-Invasive Early biomarker
(DEBBIE) consortium aims to develop this modified
ASL-MRI technique for patient-specific and robust BBB
permeability assessments. This article outlines the study
design of the DEBBIE cohorts focused on investigating
the potential of BBB-ASL as an early biomarker for AD
(DEBBIE-AD).
Methods and analysis DEBBIE-AD consists of a
multicohort study enrolling participants with subjective
cognitive decline, mild cognitive impairment and AD, as
well as age-matched healthy controls, from 13 cohorts.
The precision and accuracy of BBB-ASL will be evaluated
in healthy participants. The clinical value of BBB-ASL will
be evaluated by comparing results with both established
and novel AD biomarkers. The DEBBIE-AD study aims to
provide evidence of the ability of BBB-ASL to measure BBB
permeability and demonstrate its utility in AD and ADrelated pathologies.
Ethics and dissemination Ethics approval was obtained
for 10 cohorts, and is pending for 3 cohorts. The results of
the main trial and each of the secondary endpoints will be
submitted for publication in a peer-reviewed journal.

Involved research facilities

  • PET-Center

Permalink: https://www.hzdr.de/publications/Publ-38853


64Cu tumor labeling with hexadentate picolinic acid-based bispidine immunoconjugates

Kubeil, M.; Neuber, C.; Starke, M.; Arndt, C.; Rodrigues Loureiro, L. R.; Hoffmann, L.; Feldmann, A.; Bachmann, M.; Pietzsch, J.; Comba, P.; Stephan, H.

Abstract

Discussed are two picolinate appended bispidine ligands (3,7-diazabicyclo[3.3.1]nonane derivatives) in comparison with an earlier described bis-pyridine derivative, which are all known to strongly bind CuII. The radiopharmacological characterization of the two isomeric bispidine complexes includes quantitative labeling with 64CuII at ambient conditions with high radiochemical purities and yields (molar activities > 200 MBq/nmol). Challenge experiments in presence of EDTA, cyclam, human serum and SOD demonstrate high stability and inertness of the 64Cu-bispidine complexes. Biodistribution studies performed in Wistar rats indicate a rapid renal elimination for both 64Cu-labeled chelates. The bispidine ligand with the picolinate group in N7 position was selected for further biological experiments, and its backbone was therefore substituted with a benzyl-NCS group at C9. Two tumor target modules (TMs), targeting prostate stem cell antigen (PSCA), overexpressed in prostate cancer, and the fibroblast activation protein (FAP) in fibrosarcoma, were selected for thiourea coupling with the NCS-functionalized ligand and lysine residues of TMs. Small animal PET experiments on tumor-bearing mice showed very good and specific accumulation of the 64Cu-labeled TMs in tumors.

Keywords: bispidine; 64Cu-labeling; PET imaging; prostate stem cell antigen (PSCA); fibroblast activation protein (FAP)

Involved research facilities

  • PET-Center

Permalink: https://www.hzdr.de/publications/Publ-38852


Experiences from first time RSE class at the Computer Science Faculty of TU Dresden

Juckeland, G.

Abstract

For the first time, Introduction to Research Software Engineering was offered as a class in the Computer Science faculty of TU Dresden during this winter semester (2023/24) (https://tu-dresden.de/ing/informatik/smt/cgv/studium/lehrveranstaltungen/ws2324/RSE/index). This talk will briefly cover the content, feedback from students and own observations as well as ideas how to continue and extend the class in the future.

  • Open Access Logo Lecture (Conference)
    deRSE24 - Conference for Research Software Engineering in Germany, 05.-07.03.2024, Würzburg, Germany

Permalink: https://www.hzdr.de/publications/Publ-38851


Intriguing low-temperature phase in the antiferromagnetic kagome metal FeGe

Wenzel, M.; Uykur, E.; Tsirlin, A. A.; Pal, S.; Mathew Roy, R.; Yi, C.; Shekhar, C.; Felser, C.; Pronin, A. V.; Dressel, M.

Abstract

The properties of kagome metals are governed by the interdependence of band topology and electronic correlations resulting in remarkably rich phase diagrams. Here, we study the temperature
evolution of the bulk electronic structure of the antiferromagnetic kagome metal FeGe using infrared spectroscopy. We uncover drastic changes in the low-energy interband absorption at the 100 K structural phase transition that has been linked to a charge-density-wave (CDW) instability. We explain this effect by the minuscule Fe displacement in the kagome plane, which results in parallel bands in the vicinity of the Fermi level. In contrast to conventional CDW materials, however, the spectral weight shifts to low energies, ruling out the opening of a CDW gap in FeGe.

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Permalink: https://www.hzdr.de/publications/Publ-38850


HELIPORT: An overarching Data Management System at HZDR

Müller, S.; Gruber, T.; Juckeland, G.; Kelling, J.; Knodel, O.; Lokamani, M.; Voigt, M.; Pape, D.

Abstract

Researchers at the Helmholtz-Zentrum Dresden-Rossendorf rely on a variety of systems and tools when it comes to administer their research data. Processes involving research data management include the project planning phase (proposal submission to the beamtime proposal management system, the creation of data management plans and data policies), the documentation during the experiment or simulation campaign (electronic laboratory notebooks, wiki pages), backup- and archival systems and the final journal and data publications (collaborative authoring tools, meta-data catalogs, software and data repositories, publication systems). In addition, modern research projects are often required to interact with a variety of software stacks and workflow management systems to allow reproducibility on the underlying IT infrastructure. The "HELmholtz ScIentific Project WORkflow PlaTform" (HELIPORT), which is currently developed by researchers at HZDR and their collaborators, tries to facilitate the management of research data and metadata by providing an overarching guidance system which combines all the information by interfacing the underlying processes and even includes a workflow engine which can be used to automate processes like data analysis or data retrieval.

Keywords: Data Management; HELIPORT; FAIR

Involved research facilities

  • Data Center
  • Lecture (Conference)
    DPG Spring Meeting 2024 (Section of Particle Physics), 04.-08.03.2024, Karlsruhe, Germany

Permalink: https://www.hzdr.de/publications/Publ-38846


Directed transfer of liquid metal droplets between electrodes

Mutschke, G.; Weier, T.

Abstract

Electric fields offer an easy means to manipulate liquid metal droplets. Now, directed droplet transfer between immersed electrodes is
achieved in an alkaline electrolyte without electrical short-circuit.

Keywords: electrocapillarity; oxide films; interfacial tension; liquid metal droplets; gallium; mercury; mercury beating heart; gallium beating heart

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  • Secondary publication expected from 02.04.2025

Permalink: https://www.hzdr.de/publications/Publ-38843


Sorption data: Enhancement of geochemical modeling by chemically evident surface speciation

Bok, F.; Zechel, S.; Miron, D.; Marinich, O.; Marques Fernandes, M.

Abstract

Modeling geochemical scenarios for the safety analyses of disposal of hazardous radioactive and (chemo)toxic waste requires comprehensive and consistent thermodynamic data as well as sorption data for the surrounding host rocks. Whereas there are several projects running worldwide to develop at the comprehensive and consistent thermodynamic database for the aqueous phase and forming solids, the situation is much more complicated concerning the reactions on the mineral-water interface. For sorption data, there is currently no database providing quality assured thermodynamic surface complexation modeling (SCM) data. Even though spectroscopic methods to determine the actual surface species have made great progress in recent years, the SCM data still contain questionable to assuredly non-existent species. This leads to hardly comparable results in geochemical modeling.
To address this problem, publicly available SCM (protolysis and sorption) data are currently being reevaluated and new reaction data are generated building on spectroscopically evidenced surface complexes. Critical data gaps shall be closed by the use of analogies (for both radionuclides’ chemistry as well as the mineral phases) or established estimation methods (e.g. linear free energy relationship). The RES³T sorption database¹, the PSI Chemical Thermodynamic Database² as well as the LLNL’s sorption raw data compilation³ provide the solid basis for this work. In combination with surface site density data from crystallographic calculations, this approach yields realistic and robust models that significantly improve sorption in geochemical calculations e.g. through so-called smart Kd values⁴. The results of this work will be published within the THEREDA framework⁵ including ready-to-use parameter files for common geochemical codes (e.g. GEMS, Geochemist’s Workbench, PHREEQC).
This work is funded by BGE – the federal company for radioactive waste disposal in Germany, with the contract number TEKFuE-21-03-js.
References:
1) RES³T – Rossendorf Expert System for Surface and Sorption Thermodynamics, Helmholtz-Zentrum Dresden-Rossendorf, (https://www.hzdr.de/res3t)
2) PSI Chemical Thermodynamic Database (https://www.psi.ch/de/les/thermodynamic-databases).
3) Smart-Kd concept (https://www.smartkd-concept.de/)
4) Zavarin M. et al. (2022): Community Based Data of Uranium Adsorption onto Quartz, ESS-DIVE repository, DOI: 10.15485/1880687.
5) THEREDA – Thermodynamic Reference Database (https://www.thereda.de)

Keywords: Sorption Reference Database; SOREDA; Sorption; SCM; Surface Complexation Modelling; Thermodynamic

  • Lecture (Conference)
    American Chemical Society Spring Meeting 2024, 17.-21.03.2024, New Orleans, USA

Permalink: https://www.hzdr.de/publications/Publ-38840


Data publication: X-ray Thomson scattering absolute intensity from the f-sum rule in the imaginary-time domain

Dornheim, T.

Abstract

This repository contains the raw data for the relevant figures of the article "X-ray Thomson scattering absolute intensity from the f-sum rule in the imaginary-time domain". All data are standard gnuplot output.

Related publications

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Permalink: https://www.hzdr.de/publications/Publ-38839


Documenting ML Experiments in HELIPORT

Pape, D.; Knodel, O.; Starke, S.

Abstract

HELIPORT is a data management guidance system that aims at making the components and steps of the entire research experiment’s life cycle findable, accessible, interoperable and reusable according to the FAIR principles. It integrates documentation, computational workflows, data sets, the final publication of the research results, and many more resources. This is achieved by gathering metadata from established tools and platforms and passing along relevant information to the next step in the experiment's life cycle. HELIPORT's high-level overview of the project allows researchers to keep all aspects of their experiment in mind.

A particularly interesting use case are machine learning projects. They are often prototypical in nature and driven by iterative development, so reproducibility and tranparency are a great concern. It is essential to keep track of the relationship between input data, choices in model parameters, the code version in use, and performance measures and generated outputs at all times. This requires a data management platform that automatically records the changes made and their effects. Existing MLOps tools (such as Weights and Biases, MLFlow) live entirely in the ML domain and start their workflow with the assumption that data is available. HELIPORT, on the other hand, takes care of the data lifecycle as well. Our envisioned platform interoperates with the domain specific tools already used by the scientists, and is able to extract relevant metadata (e.g. provenance). It can also make persistent any additional information such as papers the work was based on, documentation of software components, workflows, or failure cases. Moreover, it should be possible to publish these metadata in machine-readable formats.

The challenge arising from these aspects consists in integrating ML workflows into HELIPORT in such a way that they work on the provided data and metadata. The goal is also to enable the comprehensible development of ML models alongside the experiment documented in HELIPORT. This allows different teams (e.g. experimentalists and AI specialists) to work together on the same project in a seamless manner, and help generate FAIRer outcomes. In the long term we hope to aide in establishing digital twins of facilities, and making their maintenance a part of the data management proces.

Keywords: data management; research software engineering; machine learning; metadata; ontologies

  • Open Access Logo Lecture (Conference)
    deRSE24 - 4th Conference for Research Software Engineering in Germany, 05.-07.03.2024, Würzburg, Deutschland
    DOI: 10.5281/zenodo.10807608

Permalink: https://www.hzdr.de/publications/Publ-38838


Modular and Cost-Effective Computed Tomography Design

Bieberle, A.; Hoffmann, R.; Döß, A.; Schleicher, E.; Hampel, U.

Abstract

We present a modular and cost-effective gamma ray computed tomography system for multiphase flow investigations in industrial apparatuses. It mainly comprises a Cs-137 isotopic source and an in-house-assembled detector arc, with a total of 16 scintillation detectors, offering a quantum efficiency of approximately 75% and an active area of 10 × 10 mm² each. The detectors are operated in pulse mode to exclude scattered gamma photons from counting by using a dual-energy discrimination stage. Flexible application of the computed tomography system, i.e., for various object sizes and densities, is provided by an elaborated detector arc design, in combination with a scanning procedure that allows for simultaneous parallel beam projection acquisition. This allows the scan time to be scaled down with the number of individual detectors. Eventually, the developed scanner successfully upgrades the existing tomography setup in the industry. Here, single pencil beam gamma ray computed tomography is already used to study hydraulics in gas–liquid contactors, with inner diameters of up to 440 mm. We demonstrate the functionality of the new system for radiographic and computed tomographic scans of DN110 and DN440 columns that are operated at varying iso-hexane/nitrogen liquid–gas flow rates.

Keywords: Computed Tomography Scanner; Radiation Detectors; Multi phase Investigations; Column Hydraulics; Process Intensification

Involved research facilities

  • TOPFLOW Facility

Permalink: https://www.hzdr.de/publications/Publ-38835


Latest developments in contactless inductive flow tomography

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

Abstract

Contactless Inductive Flow Tomography (CIFT) is a flow measurement technique allowing for visualizing the global flow in electrically conducting fluids. The method is based on the precise measurement of very weak induced magnetic fields arising from the fluid motion under the influence of one or several primary excitation magnetic field(s).
At HZDR the technique is used to investigate laboratory experiments on turbulent Rayleigh-Bénard convection (RBC) phenomena as well as the industrial process of continuous casting (CC) of steel. In both cases the ternary liquid metal alloy Gallium-Indium-Tin is used as a model fluid. We will present latest experimental results on both topics, including a sophisticated flow analysis for RBC by means of Proper Orthogonal Decomposition (POD) and the first CIFT online process controller for CC.
Furthermore, we will give an outlook on the latest developments, namely the two-field excitation approach to increase the accuracy of the method.

Keywords: Liquid metal technologies; turbulent flows; contactless inductive flow tomography; flow tomography; flow mapping; Rayleigh-Bénard convection; continuous casting; steel casting

  • Lecture (Conference)
    Measurement Techniques for Liquid Metals (MTLM2024), 27.-29.5.2024, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38833


An Adaptive Model for Decay Heat Estimation Using Scram Curves

Nikitin, E.; Fridman, E.; Ponomarev, A.

Abstract

This study introduces an adaptive model for estimating decay heat in nuclear reactors, particularly
during transient scenarios with steadily reducing reactor power. Traditional approaches to decay
heat calculation often rely on extensive nuclide tracking or standardized procedures. The former
approach can be resource-intensive, requiring detailed tracking of a multitude of nuclides, while the
latter often has limited applicability. The adaptive model proposed in this paper offers an alternative
solution that circumvents these challenges by utilizing precalculated decay heat curves from scram
scenarios. This methodology allows for on-the-fly decay heat calculation during simulation, adapting
to varying power levels without the need for detailed nuclide tracking.
The paper provides a description of the adaptive model, including its mathematical framework
and operational procedure. The model’s test case is developed using the IAEA benchmark exercise
related to the loss of flow without scram test conducted at the Fast Flux Test Facility, a sodium-cooled
fast reactor. The model is verified through single assembly calculations, where it demonstrates high
accuracy in comparison to the depletion solver of the Monte Carlo code Serpent. This demonstrates
the model’s potential as a promising alternative for decay heat estimation in the analysis of accident
scenarios.

Keywords: Decay heat; ULOF; SFR; DYN3D; Serpent

Related publications

  • Contribution to proceedings
    International Conference on Physics of Reactors (PHYSOR 2024), 21.-24.04.2024, San Francisco, USA
  • Lecture (Conference)
    International Conference on Physics of Reactors (PHYSOR 2024), 21.-24.04.2024, San Francisco, USA

Permalink: https://www.hzdr.de/publications/Publ-38831


Source Data: Laser-driven high-energy proton beams from cascaded acceleration regimes

Ziegler, T.; Göthel, I.; Assenbaum, S.; Bernert, C.; Brack, F.-E.; Cowan, T.; Dover, N. P.; Gaus, L.; Kluge, T.; Kraft, S.; Kroll, F.; Metzkes-Ng, J.; Nishiuchi, M.; Prencipe, I.; Püschel, T.; Rehwald, M.; Reimold, M.; Schlenvoigt, H.-P.; Umlandt, M. E. P.; Vescovi Pinochet, M. A.; Schramm, U.; Zeil, K.

Abstract

This dataset contains all source data used to generate figures and all other findings of the publication: "Laser-driven high-energy proton beams from cascaded acceleration regimes".

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-38824


Understanding vehicle-wildlife encounters: insights from animal movement datasets and road mortality surveys

Simoes Silva, I. M.; Calabrese, J.

Abstract

Wildlife-vehicle collisions are an ongoing and widespread source of biodiversity loss. Understanding how, when and why these collisions happen is a key challenge in any conservation and management efforts. Data collection with biologgers can reveal information on how animals use their environment, interact with each other, and their adaptive responses to rapid environmental changes and anthropogenic features in the landscape —including their behavioral responses to linear infrastructures. The movement ecology field is rapidly shifting as we open new avenues of research, with increased access to modern tracking technologies, collecting high-volume high-resolution movement datasets for a growing number of animal species worldwide. Using these datasets to reveal road impacts on animal behavior is fundamental, since wildlife-vehicle collisions are the second-largest source of anthropogenic mortality for many vertebrate species. We will explore empirical examples with animal tracking data, as well as information collected through road surveys, and how these can serve as crucial tools to achieve a deeper understanding of animal movement and behavior towards roads and vehicles.

Keywords: movement ecology; road ecology; biologgers; road impacts; wildlife-vehicle collisions; encounters; interactions

  • Invited lecture (Conferences)
    Applied Stochastic Processes for Encounter Problems, 05.-09.02.2024, Maryland, USA

Permalink: https://www.hzdr.de/publications/Publ-38822


HZDR Software Policy

Konrad, U.; Bieberle, A.; Bussmann, M.; Grzeganek, M.; Hüser, C.; Huste, T.; Juckeland, G.; Kaever, P.; Moravcikova, M.; Schlegel, F.; Wagner, N.; Wolf, B.

Abstract

Software is a central component of academic research and the scientific infrastructure and is devel-oped and used in all HZDR institutes. In this regulation, software refers to all forms of program code (e.g. source code together with associated documentation) and executable programs generated from it, which are developed, made available and passed on within the scope of activities at the HZDR. The development of software is an integral part of modern publication contexts consisting of written publica-tions, data sets and software. 

The policy covers the software life cycle, from software development and documentation to the transfer and maintenance of the software. The regulation is intended to support the establishment of modern software engineering methods at the HZDR, which enable high standards in software de-velopment, software quality and management. This professionalization will achieve greater sustain-ability and promote good scientific practice in terms of the verifiability and reproducibility of research results.

Keywords: Research Software Engineering; Software Development; Software Policy; HIFIS; Helmholtz

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Permalink: https://www.hzdr.de/publications/Publ-38813


Connecting Processes to Data via Meta-Data

Knodel, O.

Abstract

The presentation explores the intricate relationship between data management, computational processes and metadata descriptions. It delves into how metadata serves as a crucial bridge, facilitating the seamless connection between various data processes, RAW and derived data. The importance of the research institute's infrastructure facilities in preparing data and metadata and supporting systems such as Heliport to improve the understanding, accessibility and interoperability of data in different systems was highlighted. This research highlights the central role of metadata in optimising data-driven workflows and promoting efficient data use strategies.

Keywords: Data management; workflows; Machine Learning (ML); Heliport; Thrill

  • Open Access Logo Invited lecture (Conferences)
    Thrill WP5 ML Workshop, 27.-28.02.2024, Dresden, Germany

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Permalink: https://www.hzdr.de/publications/Publ-38811


Contribution of black carbon and desert dust to aerosol absorption in the atmosphere of the Eastern Arabian Peninsula

Mahfouz, M. M. K.; Skok, G.; Sciare, J.; Pikridas, M.; Rami Alfarra, M.; Moosakutty, S.; Alfoldy, B.; Ivančič, M.; Rigler, M.; Gregorič, A.; Podlipec, R.; Lohmann, S.; Hlawacek, G.; Heller, R.; Tutsak, E.; Močnik, G.

Abstract

Discriminating the absorption coefficients of aerosol mineral dust and black carbon (BC) in different aerosol size fractions is a challenge because of BC's large mass absorption cross-section compared to dust. Ambient aerosol wavelength dependent absorption coefficients in supermicron and submicron size fractions were determined with a high time resolution. The measurements were performed simultaneously using identical systems at an urban and a regional background site in Qatar. At each site, measurements were taken by co-located Aethalometers, one with a virtual impactor (VI) and the other with a PM1 cyclone to respectively collect super-micron-enhanced and submicron fractions. The combined measurement of aerosol absorption and scattering coefficients enabled the particles to be classified based on their optical properties' wavelength dependence. The classification reveals the presence of BC internally/externally mixed with different aerosols. Helium ion microscopy images provided information concerning the extent of mineral dust in the submicron fraction. The determination of absorption coefficients during dust storms and non-dust periods was used to establish the absorption Ångström exponent for dust and BC. Non-parametric wind regression, potential source contribution function and back-trajectory analysis reveal major regional sources of desert dust associated with north-westerly winds and a minor local dust contribution. In contrast, major BC sources found locally were associated with south-westerly winds with a smaller contribution made by offshore emissions transported by north-easterly and easterly winds. The use of a pair of Aethalometers with VI and PM1 inlets separates contributions of BC and dust to the aerosol absorption coefficient.

Keywords: helium ion microscopy; him

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-38810


Data publication: Absolute energy-dependent scintillating screen calibration for real-time detection of laser-accelerated proton bunches

Schilz, J. D.; Bodenstein, E.; Brack, F.-E.; Horst, F.; Irman, A.; Kroll, F.; Pawelke, J.; Prencipe, I.; Rehwald, M.; Reimold, M.; Schöbel, S.; Schramm, U.; Zeil, K.; Metzkes-Ng, J.

Abstract

All necessary Data to recreate the published plots and images in the publication: "Absolute energy-dependent scintillating screen calibration for real-time detection of laser-accelerated proton bunches". Included are the raw scintillating screen images, the plotting data and Python Scripts used for calculations and plotting.

Keywords: laser-driven protons; scintillating screens; absolute proton number calibration; real-time; spatially resolved; detector; calibration

Involved research facilities

  • OncoRay

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Permalink: https://www.hzdr.de/publications/Publ-38808


Optical and X-ray imaging of foam flowing through a nozzle: mapping the liquid fraction distribution and the velocity field

Lappan, T.; Skrypnik, A.; Schmidtpeter, J.; Shevchenko, N.; Eckert, S.; Sommer, A.-E.; Eckert, K.; Heitkam, S.

Abstract

In foam fractionation, to enhance the product yield, the seperation process can be intensified by the successive contraction and expansion of the aqeous foam. Performing optical bubble size measurements in combination with conductivity-based measurements of the surfactant concentration, Li et al. found that contracting the foam flow in a vertical column does neither affect the liquid flux nor the surfactant concentration, whereas a sudden expansion decreases the liquid flux. To gain comprehensive insights into the liquid fraction distribution and the velocity field of the foam while flowing through contracting or expanding geometries, we combined optical flow measurements, X-ray transmission imaging as well as X-ray particle tracking velocimetry (X-PTV) in a nozzle flow experiment as shown in Figure 1. This conference contribution presents the imaging techniques and reports experimental findings at different foam flow conditions. In the case of a diverging nozzle, we gradually increased the superficial gas velocity while keeping the bubble size constant, thus observing the transition from the expected plug flow to a detached flow including recirculation zones. In future experiments, the flow configuration investigated here will serve as a benchmark: performing parallel measurements with X-PTV, we aim to validate the approach of magnetic particle tracking (MPT) using planar Hall effect sensors.

Keywords: image analysis; nozzle flow; particle image velocimetry; particle tracking velocimetry; transmission imaging; X-ray radiography

  • Lecture (Conference)
    15th EUFOAM European Foam Conference, 30.06.-04.07.2024, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38806


Radiographic measurements of bubble flows through surface-functionalised foams

Lappan, T.; Jiao, G.; Heinrich, J.; Trtik, P.; Shevchenko, N.; Eckert, K.; Eckert, S.

Abstract

Water electrolysis produces hydrogen and oxygen gas by splitting liquid water in an electrochemical reaction. The further development of electrolysers faces currently unexplored operating conditions, particularly by increasing the electric current density, affecting the gas formation and bubble transport in the porous transport layer. Since this gas-liquid two-phase flow is not accessible by optical techniques, we employ time-resolved X-ray and neutron radiography, aiming for imaging flow measurements of the gas transport by mapping the local gas fraction distribution over time. On a laboratory scale, we performed radiographic imaging of bubble flows through open-porous metal and polymer foams of different pore size and surface functionalisation. This conference contribution presents main conclusions of our experimental study and showcases the advantages but also limitations of X-ray or neutron radiography for investigating multiphase flows within optically opaque structures. We observed preferred motion paths of bubbles and found that especially small bubbles are significantly slowed down when flowing through the foam structures, even in the case of a hydrophilic surface character. In summary, we visualised the gas transport depending on the bubble size in relation to the foam pore size and the wettability of the inner foam surface, thus highlighting the potential of radiographic techniques.

Keywords: gas-liquid two-phase flow; metal foam; neutron radiography; polymer foam; X-ray radiography

  • Poster
    16th International Conference on Gas–Liquid and Gas–Liquid–Solid Reactor Engineering, 02.-05.09.2024, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38805


Towards the Stable Binding of Mercury: Synthesis and Functionalization of Dibenzyldiazabicyclononane Scaffolds

Weber, T.; Krönke, T.; Köckerling, M.; Walther, M.; Pietzsch, H.-J.; Kopka, K.; Mamat, C.

Abstract

A new and universally applicable synthesis route for the preparation of functionalized diazabicyclononane compounds was elaborated starting from an easily available 1,5-diphenyl-3,7-diazabicyclo[3.3.1]nonan-9-ol by alkylation of both secondary amines with modified benzyl residues having a bromo, trimethylstannyl, trimethylsilyl, and pinacolboranyl residue in high yields (65-88%). All compounds were used for mercuration reactions to stably bind Hg2+. Finally, the C-9 position of two functionalized diazabicyclononanes was further modified by introducing an azide function allowing a later attachment to biomolecules of interest by using click chemistry.

Keywords: organomercury; diazabicyclononane; Auger electrons

Permalink: https://www.hzdr.de/publications/Publ-38804


Highlight selection of radiochemistry and radiopharmacy developments by editorial board

Toyohara, J.; Vugts, D.; Kiß, O.; Todde, S.; Li, X.-G.; Liu, Z.; Yang, Z.; Gillings, N.; Cazzola, E.; Szymanski, W.; van der Meulen, N.; Reilly, R.; Taddei, C.; Schirrmacher, R.; Li, Z.; Lagebo, Y. J.; Bentaleb, N.; de Souza Albernaz, M.; Lapi, S.; Ramogida, C.; Mukherjee, A.; Ajenjo, J.; Deuther-Conrad, W.; Bourdeau, C.

Abstract

Background: The Editorial Board of EJNMMI Radiopharmacy and Chemistry releases a biannual highlight commentary to update the readership on trends in the field of radiopharmaceutical development.

Main Body: This selection of highlights provides commentary on 24 different topics selected by each coauthoring Editorial Board member addressing a variety of aspects ranging from novel radiochemistry to first-in-human application of novel radiopharmaceuticals.

Conclusion: Trends in radiochemistry and radiopharmacy are highlighted. Hot topics cover the entire scope of EJNMMI Radiopharmacy and Chemistry, demonstrating the progress in the research field in many aspects.

Permalink: https://www.hzdr.de/publications/Publ-38802


Nonperturbative Floquet engineering of the toric-code Hamiltonian and its ground state

Petiziol, F.; Wimberger, S.; Eckardt, A.; Mintert, F.

Abstract

We theoretically propose a quantum simulation scheme for the toric-code Hamiltonian, the paradigmatic model of a quantum spin liquid, based on time-periodic driving. We develop a hybrid continuous-digital strategy that exploits the commutativity of different terms in the target Hamiltonian. It allows one to realize the required four-body interactions in a nonperturbative way, attaining strong coupling and the suppression of undesired processes. In addition, we design an optimal protocol for preparing the topologically ordered ground states with high fidelity. A proof-of-principle implementation of a topological device and its use to simulate the topological phase transition are also discussed. The proposed scheme finds natural implementation in architectures of superconducting qubits with tunable couplings.

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Permalink: https://www.hzdr.de/publications/Publ-38801


Absolute energy-dependent scintillating screen calibration for real-time detection of laser-accelerated proton bunches

Schilz, J. D.; Bodenstein, E.; Brack, F.-E.; Horst, F.; Irman, A.; Kroll, F.; Pawelke, J.; Prencipe, I.; Rehwald, M.; Reimold, M.; Schöbel, S.; Schramm, U.; Zeil, K.; Metzkes-Ng, J.

Abstract

Laser-plasma accelerators (LPAs) can deliver pico- to nanosecond long proton bunches, with ≥∼100 nC of charge dispersed over a broad energy spectrum. Increasing the repetition rates of today’s LPAs is a necessity for their practical application. This, however, creates a need for real-time proton bunch diagnostics. Scintillating screens are one detector solution, commonly applied in the field of electron LPAs for spatially resolved particle and radiation detection, yet their establishment for LPA proton detection is only slowly taking off. This is also due to the lack of available calibrations. In this paper, we present an absolute proton number calibration for the scintillating screen type DRZ High (Mitsubishi Chemical Corporation, Düsseldorf, Germany), one of the most sensitive screens according to calibrations for relativistic electrons and x-rays. For proton irradiation of the DRZ High screen, we find an increase in light yield of >60% compared to reference calibration data for relativistic electrons. The presented absolute light yield calibration shows an uncertainty of the proton number of 10% and can seamlessly be applied at other LPA facilities. Moreover, we investigate the scintillating screen light yield dependence on proton energy, since many types of scintillators (e.g., plastic, liquid, inorganic) show a reduced light yield for increased local energy deposition densities, an effect termed ionization quenching. The ionization quenching can reduce the light yield for low-energy protons by up to ∼20%. This work provides all necessary data for absolute spectral measurements of LPA protons with DRZ High scintillating screens, e.g., when these are used as detectors in the commonly available Thomson parabola spectrometers.

Keywords: laser-driven protons; scintillating screens; absolute proton number calibration

Involved research facilities

  • OncoRay

Related publications

Permalink: https://www.hzdr.de/publications/Publ-38800


Bubble paths in two-phase flows through open-porous foams: Imaging measurements by X-ray and neutron radiography

Lappan, T.; Jiao, G.; Heinrich, J.; Trtik, P.; Michak, R. L.; Shevchenko, N.; Eckert, K.; Eckert, S.

Abstract

In water electrolysis, the porous transport layer (PTL) is an essential component of both proton (PEM) as well as anion exchange membrane (AEM) electrolysers. Besides establishing an electrical contact, the PTL enables the electrolyte to be transported to the anode. In the opposite direction, the oxygen (O2) formed at the anode must be transported away, resulting in a complex counterflow of liquid and gas through the PTL, thus limiting the mass transport and, consequently, the conversion of electrical energy. The further development of electrolysers faces so far unexplored operating conditions, in particular by increasing the electric current density. This, in turn, affects the formation and transport of gas bubbles in the PTL, which is not yet sufficiently understood.

As the gas-liquid two-phase flow in the PTL is inaccessible for flow measurement by optical methods, we employed time-resolved X-ray and neutron radiography. Using the model experiment sketched in Fig. 1, we aimed for imaging measurements of the gas transport through open-porous foam by mapping the gas fraction distribution over time. In previous experimental studies, we have used X-ray and neutron radiography for flow visualisation in optically opaque fluids such as liquid metal [1] and aqueous foam [2]. Similar to the approach of radiographic measurements of the liquid fraction in aqueous foam [3], this conference contribution showcases the detection and tracking of bubbles based on their gas fraction in X-ray or neutron images. As exemplarily illustrated in Fig. 2, we observed preferred paths of the bubbles moving upwards through the open-porous foam samples. Moreover, we found that bubbles smaller than the pore size are significantly slowed down, even in the case of a hydrophilic surface character of the foam. In summary, the measurement results and conclusions from our experimental parameter study are available for comparison with computational fluid dynamics.

  • Poster
    Gemeinsames Jahrestreffen der DECHEMEA / VDI Fachgruppen MPH & CFD & AT, 20.-21.03.2024, Bremen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38799


Synthesis and Twin Polymerization of Si(OCH2py)4 for Nitrogen-containing Carbon Materials

Scharf, S.; Notz, S.; Pfefferkorn, K.; Rüffer, T.; Formánek, P.; Hübner, R.; Selyshchev, O.; Madeira, T. I.; Zahn, D. R. T.; Lang, H.

Abstract

The synthesis and twin polymerization (TP) of Si(OCH2py)4 (3a, py=2-cC5H4N; 3b, py=3-cC5H4N; 3c, py=4-cC5H4N) is discussed. The solid state structures of 3b, c were confirmed by single-crystal X-ray crystallography showing non-conventional H-bonding, forming 2D chains (3b) or 3D networks (3c). Thermally induced TP of 3a–c and their simultaneous polymerization with 2,2‘-spiro-bi[4H-1,3,2-benzodioxasiline] (4) is described. The resulting hybrid materials were characterized by 1H, 13C{1H}, and 29Si{1H} CP MAS NMR spectroscopy confirming the transformation of the SiOCH2 moieties into CH2 groups enabling the formation of the respective polymers. These results were supported by HAADF-STEM studies, displaying micro-structuring. Nitrogen-containing porous carbon materials C_1–C_3 show surface areas of 1300 and 1700 m2g-1, large pore volumes between 0.6–1.2 cm3g-1, and nitrogen contents of up to 3.1 at-%. X-ray photoemission spectroscopy reveal that pyrrolic, pyridine, and pyridone nitrogen atoms are present. If equimolar amounts of 3a–c and 4 are simultaneously polymerized in the presence of [Pd(OAc)2] (5), then the Pd nanoparticle-decorated material Pd@C_3 (900 m2g-1) was obtained, which showed k values of -0.083 and -0.066 min-1 in the reduction of methylene blue and methyl orange, proving the accessibility of the Pd NPs.

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-38798


Reproducibility of Arterial Spin Labeling Cerebral Blood Flow image processing: A Report of The ISMRM Open Science Initiative for Perfusion Imaging and the ASL MRI Challenge

Paschoal, A. M.; Woods, J. G.; Pinto, J.; Bron, E. E.; Petr, J.; Kennedy McConnell, F. A.; Bell, L.; Dounavi, M.-E.; van Praag, C. G.; Mutsaerts, H.-J.; Oliver Taylor, A.; Zhao, M. Y.; Brumer, I.; Siang Marcus Chan, W.; Toner, J.; Hu, J.; Zhang, L. X.; Domingos, C.; Monteiro, S. P.; Figueiredo, P.; Harms, A. G. J.; Padrela, B.; Tham, C.; Abdalle, A.; Croal, P. L.; Anazodo, U.

Abstract

Purpose: Arterial Spin Labeling (ASL) is widely used in clinical research as a contrast-free MRI method for
assessment of cerebral blood flow (CBF). While the recommended guideline for ASL acquisition is
generally adopted to standardize quantification of CBF, ASL analysis still produces wide variability in CBF
estimates, limiting research and clinical interpretation of ASL results. This study explored the extent of
variability in ASL CBF quantification through the ISMRM OSIPI ASL MRI Challenge. The goal of the challenge
was to minimize sources of variability in ASL analysis by establishing best practice in ASL data processing
to make ASL analysis more reproducible and clinically meaningful.
Methods: Eight international teams analyzed the challenge data consisting of a high-resolution T1-
weighted anatomical image and ten pseudo-continuous ASL (PCASL) datasets. The datasets were
simulated using an ASL digital reference object to produce ground-truth CBF values in normal and
pathological states. The accuracy of CBF quantification from each team’s analysis was compared to
ground-truth values across all voxels and within pre-defined brain regions. Reproducibility of CBF
estimates across analysis pipelines was assessed using intra-class correlation coefficient (ICC), the limits
of agreement (LOA) and the replicability of generating similar CBF estimates from the image processing
approaches as documented.
Results: The absolute errors in CBF estimates compared to the ground-truth synthetic data ranged from
18.36 to 48.12 ml/100g/min. Realistic motion incorporated in three of the ten synthetic data produced
the largest absolute CBF error, largest variability between teams, and the least agreement (ICC and LOA)
with ground truth results. Fifty percent (4/8) of the teams’ methods were replicated, and one method
produced three times larger CBF errors (46.59 ml/100g/min) compared to submitted results.
Conclusions: The apparent variability in CBF measurements, influenced by differences in image processing
strategies, particularly in compensating for motion, demonstrates the significance for standardization of
ASL image analysis workflow. Therefore, we provide a recommendation for ASL image processing based
on top performing approaches as a step towards standardization of ASL imaging for clinical use.

Involved research facilities

  • PET-Center

Permalink: https://www.hzdr.de/publications/Publ-38797


Mapping the slow and fast photoresponse of field-effect transistors to terahertz and infrared radiation

Regensburger, S.; Ludwig, F.; Winnerl, S.; Klopf, J. M.; Lu, H.; Roskos, H. G.; Preu, S.

Abstract

Field-effect transistors are capable of detecting electromagnetic radiation from less than 100 GHz up to very high frequencies reaching well into the infrared spectral range. Here, we report on frequency coverage of up to 30THz, thus reaching the technologically important frequency regime of CO2 lasers, using GaAs/AlGaAs high-electron-mobility transistors. A detailed study of the speed and polarization dependence of the responsivity allows us to identify a cross over of the dominant detection mechanism from ultrafast non-quasistatic rectification at low Terahertz frequencies to slow rectification based on a combination of the Seebeck and bolometric effects at high frequencies, occurring at about the boundary between the Terahertz frequency range and the infrared at 10THz.

Keywords: THz detection; FEL; FELBE; ultrafast

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Permalink: https://www.hzdr.de/publications/Publ-38796


Annual Report 2023 - Institute of Resource Ecology

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

Abstract

The IRE is one of the ten institutes of the Helmholtz-Zentrum Dresden-Rossendorf (HZDR). Our research ac-tivities are mainly integrated into the program “Nuclear Waste Management, Safety and Radiation Research (NUSAFE)” of the Helmholtz Association (HGF) and fo-cus on the topics “Safety of Nuclear Waste Disposal” and “Safety Research for Nuclear Reactors”. The program NUSAFE, and therefore all work which is done at IRE, belong to the research field “Energy” of the HGF.

  • Open Access Logo Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-128 2024
    ISSN: 2191-8708, eISSN: 2191-8716

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Permalink: https://www.hzdr.de/publications/Publ-38795


Application of solvent extraction process for zinc recovery from old silver mine “Davidschachthalde” tailings

Kelly, N.; Aamir, M. H.; Helbig, T.; Werner, A.; Patil, A. B.

Abstract

The historic mining activities have produced a vast amount of mine tailings covering a huge landscape and containing hazardous substances that are harmful to the environment. In addition, the mine tailings also contain valuable materials that become economical after a certain period depending on the criticality of the commodity. Likewise, the old silver mine tailings “Davidschachthalde” near Freiberg, Germany, bears hazardous substances such as As, Cd and valuable elements such as Zn, In, and Cu. Thus, an innovative flowsheet is developed to recover Zn from mine tailings. Firstly, the Fe and Al are removed using the precipitation method which also removes As. Then, the solution is passed through the cementation steps for Cu and Cd removal. In order to purify and enrich Zn(II) in the aqueous solution before electrowinning the conceptional flowsheet consists of a solvent extraction process.
The filtrate from precipitation steps with the composition of 1120 mg/L Zn(II), 4 mg/L Cu(II), 10 mg/L Al(III), 243 mg/L Ca(II), 21 mg/L Cd(II) and pHini 4.7 is subjected to solvent extraction unit with 3 extraction and 2 stripping stages in MEAB lab scale Mixer Settler. Figure 1 depicts the results for the extraction step which is carried out with 0.5 M Cyanex® 272 in kerosene as the organic phase, A/O ratio of 1:1, a contact time of 10 min with a 1-hour sampling interval. Under the chosen conditions Zn(II) extraction is 89% after reaching equilibrium and shows a high selectivity related to low concentrated impurities Cu(II), Cd(II) and Al(III). However, a Ca(II) co-extraction of up to 22% is observed during the process which would affect the following stripping and electrowinning processes in a negative way. Therefore, a high selectivity between Zn(II) and Ca(II) needs to be achieved in the extraction step.
Here, we report the development of the highly selective solvent extraction process for the Zn(II) containing solutions generated during the previous precipitation and cementation steps. Effects of crucial parameters such as pH control and A/O ratio as well as the composition of the stripping agent on extraction yields, up-concentration and selectivity are discussed in detail.

Keywords: ReminingPlus; Davidschachthalde; Mine tailings; Selective Solvent Extraction; Cyanex 272

Involved research facilities

  • Metallurgy Technical Centre
  • Lecture (Conference)
    Annual Meeting of DECHEMA/VDI Group Extraction, 14.-15.02.2024, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-38794


Mission: Impossible - Understanding Regulations For Radiopharmaceuticals

Kiß, O.

Abstract

Mission: Impossible - Understanding Regulations For Radiopharmaceuticals

  • Invited lecture (Conferences)
    Danish Radiochemistry Meeting, 02.-03.05.2024, Nyborg, Dänemark

Permalink: https://www.hzdr.de/publications/Publ-38792


Outcome from an ITF EMA meeting of PRISMAP (quality requirements for new radionuclides in clinical trials)

Kiß, O.

Abstract

Outcome from an ITF EMA meeting of PRISMAP (quality requirements for new radionuclides in clinical trials)

  • Invited lecture (Conferences)
    21st European Symposium on Radiopharmacy & Radiopharmaceuticals ESRR'24, 18.-21.04.2024, Coimbra, Portugal

Permalink: https://www.hzdr.de/publications/Publ-38791


Radionuclide Theranostics for Alpha-Therapy using Lanthanum-133

Kiß, O.

Abstract

The 2nd International Conference on Molecular Probes on Advancements in Next-Generation Theranostics: Small Scaffold Proteins, Nanomaterials, Molecular Targets & Targeted Alpha-Therapy

Involved research facilities

  • ZRT
  • Invited lecture (Conferences)
    The 2nd International Conference on Molecular Probes on Advancements in Next-Generation Theranostics: Small Scaffold Proteins, Nanomaterials, Molecular Targets & Targeted Alpha-Therapy, 21.02.2024, Bangkok, Thailand

Permalink: https://www.hzdr.de/publications/Publ-38788


The effects of fracture cross-scale surface roughness in crystalline host rocks on hydrodynamics studied by 3D modeling

Zhou, W.; Kulenkampff, J.; Heredia, D. J.; Schäfer, T.; Fischer, C.

Abstract

This data provides the original inputs and COMOSL scripts for the paper 'The effects of fracture cross-scale surface roughness in crystalline host rocks on hydrodynamics studied by 3D modeling'. 

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Permalink: https://www.hzdr.de/publications/Publ-38787


Value of [18F] FDG PET/CT parameters of the primary tumor in assessing overall survival in NSCLC patients with cN1-cN3 lymph nodes involvement

Cegla, P.; Hofheinz, F.; Czepczyński, R.; Witkowska, K.; van den Hoff, J.; Trojanowski, M.; Bos-Liedke, A.; Cholewinski, W.

Abstract

Background: The aim of this retrospective study was to assess the value of 18F-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography ([18F]FDG PET/CT parameters in cN1-cN3 non-small cell lung cancer (NSCLC) patients.

Materials and methods: 59 consecutive patients (35 M, 24 F) with NSCLC who underwent pretreatment [18F]FDG PET/CT were enrolled to this study. Several primary tumor PET parameters, including the maximum and mean standardized uptake value (SUVmax and SUVmean), the metabolic active tumor volume (MTV) and the total lesion glycolysis (TLG = MTVxSUVmean), were extracted and analysed. Overall survival was defined as time from primary diagnosis to death or the last info.

Results: In the whole analysed group 44 patients underwent curative treatment, while 15, because of the severity of the disease, were classified for palliative treatment. Univariate Cox analysis of clinical and metric PET parameters revealed that MTV was a significant prognostic factor for OS (p = 0.024), while TLG and curative treatment showed a trend for significance (p < 0.1). In multivariate Cox regression (MTV and curative treatment) MTV remained a significant factor (p = 0.047).

Conclusions: Metabolic tumor volume of the primary tumor was the only independent prognostic factor for cN1–cN3 NSCLC patients.

Keywords: positron emission tomography/computed tomography; NSCLC; overall survival

Involved research facilities

  • PET-Center
  • Open Access Logo Reports of Practical Oncology and Radiotherapy 29(2024)1, 97-102
    DOI: 10.5603/rpor.99360

Permalink: https://www.hzdr.de/publications/Publ-38786


Pioneering Digital Research Landscapes: Innovations at HZDR

Knodel, O.

Abstract

Digital infrastructures have become indispensable in the field of modern research and science. These technological frameworks play a crucial role for the entire research cycle, supporting literature searches, aiding in data collection and analysis, facilitating the creation and publication of scholarly works, and ensuring the thorough documentation and long-term storage of research findings. Additionally, these infrastructures serve as a vital means for networking and communication among peers, creating the essential foundation of an open and transparent science and research ecosystem.
In this lecture, the entire digital research landscape at the HZDR will be presented and illustrated using a representative experiment.

Keywords: Data management; Heliport; FAIR; Data provenance; metadata; workflows

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    Helmholtz Open Science Forum: Towards Open Digital Research Ecosystems – Interconnecting Infrastructures, 14.02.2024, online, online

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Permalink: https://www.hzdr.de/publications/Publ-38785


Functionalization of Tetraphosphido Ligands by Heterocumulenes

Hauer, S.; Balázs, G.; Gliese, F.; Meurer, F.; Horsley Downie, T. M.; Hennig, C.; Weigand, J. J.; Wolf, R.

Abstract

Although numerous polyphosphido complexes have been accessed through the transition-metal-mediated activation and functionalization of white phosphorus (P4), the selective functionalization of the polyphosphorus ligands in these compounds remains underexplored. In this study, we explore the reactions between cyclotetraphosphido cobalt complexes and heterocumulenes, leading to functionalized P4 ligands. Specifically, the reaction of carbon disulfide (CS2) with [K(18c 6)][(Ar*BIAN)Co(η4-P4)] ([K(18c 6)]1, 18c 6 = [18] crown 6) affords the adduct [K(18c 6)][(Ar*BIAN)Co(η3:η1-P4CS2)] ([K(18c 6)]3), in which CS2 is attached to a single phosphorus atom (Ar* = 2,6-dibenzhydryl-4-isopropylphenyl, BIAN = 1,2-bis(arylimino)acenaphthene diimine). In contrast, the insertion of bis(trimethylsilyl)sulfur diimide S(NSiMe3)2 into a P−P bond of 1− yields [K(18c 6)][(Ar*BIAN)Co(η3:η1-P4SN2(SiMe3)2] (K(18c 6)]4). This salt further reacts with Me3SiCl to form [(Ar*BIAN)Co(η3:η1-P4SN2(SiMe3)3] (5), featuring a rare azatetraphosphole ligand. Moreover, treating the previously reported complex [(Ar*BIAN)Co(η3:η1-P4C(O)tBu)] (2) with isothiocyanates results in P−C bond insertion, yielding [(Ar*BIAN)Co(η3:η1-P4C(S)N(R)C(O)tBu)] (6a b; R = Cy, Ph).

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Permalink: https://www.hzdr.de/publications/Publ-38782


RevCAR-expressing immune effector cells for targeting of Fn14-positive glioblastoma

Abdelfatah Saleh Hassan, H. A.; Mitwasi, N.; Rodrigues Loureiro, L. R.; Kegler, A.; Elizabeth González Soto, K.; Hoffmann, L.; Crespo, E.; Arndt, C.; Bergmann, R.; Bachmann, M.; Feldmann, A.

Abstract

In more recent studies we have established the unique adaptor chimeric antigen receptor (CAR) platform RevCAR which uses as extracellular CAR domain a peptide epitope instead of an antibody domain. RevCAR adaptors (termed RevCAR target modules, RevTMs) are bispecific antibodies. The reversible ON/OFF switch of the RevCAR system improves the safety compared to conventional CARs. Here we describe for the first time its use for retargeting of both T- and NK-92 cells. In addition, we describe the development and preclinical validation of a novel RevTM for targeting of the fibroblast growth factor-inducible 14 (Fn14) surface receptor which is overexpressed on Glioblastoma (GBM) cells and therefore a promising target for the treatment of GBM. The novel RevTM efficiently redirects RevCAR modified T- and NK92 cells and leads to the killing of GBM cells both in vitro and in vivo. Tumor cell killing is associated with increased IL-2, TNF-α and/or IFN-γ secretion. Hence, these findings give an insight into the complementary potential of both RevCAR T and NK-92 systems as a safe and specific immunotherapeutic approach against GBM.

Keywords: Glioblastoma; Fn14; CAR T cell; CAR NK-92 cell; adaptor CAR; immunotherapy

Permalink: https://www.hzdr.de/publications/Publ-38781


A comparative compositional study of Egyptian glass from Amarna with regard to cobalt sources and other colourants

Hodgkinson, A. K.; Lemasson, Q.; Mäder, M.; Munnik, F.; Pichon, L.; Röhrs, S.; Reiche, I.

Abstract

A selection of Late Bronze Age glass objects from the site of Amarna (Egypt) was analysed for their overall chemical composition, colourants and transition metals associated with the sources of cobalt ore. The objects were analysed by means of Particle Induced X-Ray and Gamma-ray Emission and Rutherford Backscattering Spectrometry at the IBC, HZDR, Dresden and the New AGLAE facility, C2RMF, Paris. The data was subsequently compared with further measurements obtained by portable X-Ray Fluorescence (and by Laser-Ablation Inductively-Coupled-Plasma Mass-Spectrometry) in order to sound the potential of these non-destructive methods to obtain new insights into the production process of glass from Amarna and its provenancing.

Keywords: Glass; Amarna; Egypt; PIXE; PIGE; RBS; microPIXE-imaging; Trace elements; Cobalt sources; Colourants

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Permalink: https://www.hzdr.de/publications/Publ-38780


Assessment of anthropogenic actinide background levels on HZDR’s research campus

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

Abstract

The new multi-purpose 1-MV AMS facility HAMSTER (Helmholtz Accelerator Mass Spectrometer for Tracing Environmental Radionuclides) in Dresden-Rossendorf will get in operation in 2024. The new machine is dedicated to the analysis of ultra-trace levels of actinides in environmental samples. Thus, the aim of this study is to assess the actinide background on HZDR’s research campus to rule out any potential contamination caused by the former research reactor onsite. Hence, several soil samples close to the construction site of the new accelerator building and former radioisotope production facilities
have been analyzed. The samples have been processed in the existing chemistry labs of HZDR’s 6-MV DREAMS facility and the newly established
HAMSTER labs showing comparable low background levels. The measured Pu concentrations and isotopic ratios are in agreement with global fallout signature. However, in some samples increased 236U concentrations and relatively low 233U/236U atomic ratios have been detected pointing to an additional source of 236U. Additional sample analysis will be performed with HAMSTER in 2024.

  • Lecture (Conference)
    DPG Frühjahrstagung, 13.03.2024, Freiburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38777


Development and improvement of radiochemical separation schemes for actinide determination using AMS

Wolf, J.; Koll, D.; Zwickel, S.; Fichter, S.; Hotchkis, M.; Wallner, A.

Abstract

The determination of minute amounts of actinides in a huge variety of sample matrices is a challenging task. The current capabilities of state-of-the-art accelerator mass spectrometers enable detection limits close to a few hundred atoms per sample. However, proper sample preparation is inevitable to separate the element of interest from the overwhelming majority of the sample mass. Here, we present some of our current activities regarding the optimization of work-up procedures for different actinides (i.e. Pa, Np, Pu, Am, Cm) from environmental samples like water, soil, deep sea ferromanganese crusts and lunar
regolith.

  • Poster
    DPG Frühjahrstagung, 12.03.2024, Freiburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38776


Case studies of three geological archives for rare radionuclide measurements using Accelerator Mass Spectrometry

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

Abstract

Long-lived radionuclides in our environment provide important information on natural and anthropogenic processes. Their
presence and concentration reflect the balance of production and decay. Geological archives store such information and the nuclides
can be chemically extracted from the bulk sample. Accelerator mass spectrometry (AMS) represents a sensitive method to quantify
those nuclides at natural levels. Three different terrestrial archives are discussed here as examples for radionuclide extraction
using various chemical separation methods for subsequent AMS measurements. We focus on sample preparation for the cosmogenic
radionuclides Be-10 and Al-26, various anthropogenic actinide isotopes such as U, Pu and Am as well as the astrophysically
interesting nuclides Ca-41, Mn-53 and Fe-60. The processed materials cover samples with masses between a few mg and up to a
few hundred kg and protocols are presented for the quantitative extraction of some 10,000 atoms of cosmogenic or interstellar
origin per sample and even as low as a few hundred actinide atoms.

Keywords: Accelerator Mass Spectrometry; Radionuclides; Environment; Chemical Purification; Astrophysics

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-38775


Search for r-process Pu-244 in the K-Pg boundary layer

Koeberl, C.; Fichter, S.; Hotchkis, M. A. C.; Child, D.; Froehlich, M.; Hartnet, M.; Koll, D.; Merchel, S.; Wallner, A.

Abstract

The K-Pg (Cretaceous–Paleogene) boundary at 66 Ma marks one of five major mass extinctions in Earth’s fossil history. Based on strong enrichments of the platinum-group elements in the boundary layer, Alvarez et al. [1], in 1980, suggested that the impact of a large asteroid was responsible for the K/Pg event.
Earlier, other possible causes for the mass extinction, e.g., a nearby supernova(SN)-explosion, were also discussed, and indeed also Alvarez et al. initially considered this option to explain the high Ir concentration. However, to explain the observed Ir content, the distance for a SN would have to be less than one light-year. To exclude the SN option for the K-Pg event, they searched for a specific long-lived radionuclide, 244Pu, which has a half-life of 81 Myr and does not exist naturally on Earth. Assuming that this radionuclide is predominantly produced and ejected in SNe, its presence could indicate a nearby SN. No 244Pu at required levels was detected, leaving an impact as the most plausible cause (which was later confirmed by the discovery of shocked minerals and also a source crater, Chicxulub). However, since 1980, strong evidence evolved that the heavy r-process elements, e.g., actinides such as 244Pu, are produced in rare explosive events (ca. 1000 times less frequent than common type II core-collapse SNe in the galaxy) [2]. Neutron star mergers are potential candidates or rare subsets of SNe. Thus, the common core-collapse SNe might not have contributed significantly to actinide nucleosynthesis for the past few 100 Myr. This assumption agrees also with recent observations following the gravitational-wave event GW170817 [3]. Furthermore, by searching deep-sea archives for interstellar signatures we confirmed recently that nucleosynthesis yields of 244Pu are much lower (possibly a factor of 100) than expected if SNe dominate heavy isotope r-process nucleosynthesis [4-6]. However, the detection of a significant 244Pu influx above background into these terrestrial archives suggests the possibility of a nearby explosive event within the past few hundred millions years, possibly from a rare event. Thus, a small r-process contribution to actinide production from SNe is still a possibility. In general, site and frequency of r-process events are still strongly debated [2]. Thus, in contrast to the assumption of Alvarez et al. [1], it is not clear that non-detection of 244Pu excludes a nearby supernova explosion at 66 Ma. Despite the overwhelming evidence for an asteroid impact, a new method for direct atom counting has emerged with superior detection efficiency for 244Pu: since the original work by Alvarez et al. in 1980, the 244Pu detection-sensitivity has improved by more than a factor of a million by applying the method of Accelerator Mass Spectrometry (AMS) [5,7,8]. This enormous gain in abundance sensitivity prompted us to reinvestigate the 244Pu concentration in the K-Pg boundary layers. Here we present first results for a set of samples covering this transition period from the Cretaceous to the Paleogene.

  • Poster
    55th Lunar and Planetary Science Conference, 12.03.2024, The Woodlands, USA

Permalink: https://www.hzdr.de/publications/Publ-38774


Investigating the interaction of uranium(VI) with diatoms and their bacterial community: A microscopic and spectroscopic study

He, Y.; Wei, T.-S.; Kluge, S.; Flemming, K.; Sushko, V.; Hübner, R.; Steudtner, R.; Raff, J.; Mallet, C.; Beauger, A.; Breton, V.; Péron, O.; Stumpf, T.; Sachs, S.; Montavon, G.

Abstract

Diatoms and bacteria play a vital role in investigating the ecological effects of heavy metals in the environment. Despite separate studies on metal interactions with diatoms and bacteria, there is a significant gap in research regarding heavy metal interactions within a diatom-bacterium system, which closely mirrors natural conditions. In this study, we aim to address this gap by examining the interaction of uranium(VI) (U(VI)) with Achnanthidium saprophilum freshwater diatoms and their natural bacterial community, primarily consisting of four successfully isolated bacterial strains (Acidovorax facilis, Agrobacterium fabrum, Brevundimonas mediterranea, and Pseudomonas peli) from the diatom culture. Uranium (U) bio-association experiments were performed both on the xenic A. saprophilum culture and on the four bacterial isolates. Scanning electron microscopy and transmission electron microscopy coupled with spectrum imaging analysis based on energy-dispersive X-ray spectroscopy revealed a clear co-localization of U and phosphorus both on the surface and inside A. saprophilum diatoms and the associated bacterial cells. Time-resolved laser-induced fluorescence spectroscopy with parallel factor analysis identified similar U(VI) binding motifs both on A. saprophilum diatoms and the four bacterial isolates. This is the first work providing valuable microscopic and spectroscopic data on U localization and speciation within a diatom-bacterium system, demonstrating the contribution of the co-occurring bacteria to the overall interaction with U, a factor non-negligible for future modeling and assessment of radiological effects on living microorganisms.

Keywords: Achnanthidium saprophilum; 16S rRNA genes; Extracellular polymeric substance (EPS); Co-localization; Luminescence spectroscopy; Radionuclides; Uranium

Permalink: https://www.hzdr.de/publications/Publ-38772


Measurements of sodium flow rates in the high temperature KASOLA and SOLTEC-2 facilities

Onea, A.; Ruck, S.; Krauter, N.; Vielhaber, S.; Schmidt, R.

Abstract

The present study presents the experimental measurements of the sodium flow rate in the KASOLA (KArlsruhe SOdium LAboratory) and SOLTEC-2 (SOdium Loop for TEst materials
and Corrosion) facilities available at KIT. KASOLA facility is a versatile sodium facility designed for thermal-hydraulic experiments and tests of components at prototypical and industrial scale [1]. The facility has a sodium inventory of 7 m3 and can be operated up to a temperature of 550°C at an overpressure of 2.5 bar. The maximal flow rate is specified at 150 m3/h, which can be achieved with a 75 kW annular linear induction pump. The sodium flow rate measurements have been performed using a Coriolis flowmeter, which has been used as reference for the calibration of a magnetic flow meter. The influence of the temperature field has been considered in the determination of the flow rate curve for the magnetic flow rate sensor. SOLTEC-2 facility is a 720 °C high temperature sodium loop currently used for experimental investigations of sodium corrosion on high temperature steels. The facility has a sodium inventory of ~14 L and it was operated up to 720 °C at an overpressure of 2.5 bar. The maximal mass flow rate specified is 300 kg/h. An innovative eddy current flowmeter (ECFM) sensor developed at HZDR, Dresden [2] has been installed in the high temperature side and operated in the SOLTEC loop. Successful measurements have been performed up to 700 °C, which to our knowledge represent so far a worldwide premiere. A comparison has been made between the results generated by the ECFM sensor with the experimental data delivered by the magnetic fly-wheel that is installed in the low temperature side of the loop. The study discusses the experience gained and the differences between these two flow rate sensors.

Keywords: Measurement; flow rate; sodium; high temperature

  • Lecture (Conference)
    4th International Workshop on Measuring Techniques for Liquid Metal Flows, 27.-29.05.2024, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38771


A Look-up-Table Method for Simultaneous Measurement of Flow Velocity and Electrical Conductivity of a Liquid Metal Using an Eddy Current Flow Meter

Krauter, N.; Stefani, F.

Abstract

Measuring the flow velocity of liquid metals is a challenging task due to their high temperatures, their opacity and in many cases their chemical reactivity. There are several inductive methods to measure the flow velocity of liquid metals such as contactless inductive flow tomography (CIFT) [1], the magnetic distortion probe [2], Lorentz force velocimetry [3], the phase shift sensor [4] and eddy current flow meters (ECFM)[5]. ECFMs are often used in liquid metal fast breeder reactors due to their reliability and simple design. A disadvantage of the ECFM is that its output signal is influenced not only by changes in the flow velocity, but also by the electrical conductivity of the liquid metal, which depends on its temperature. Therefore, the ECFM must be calibrated according to the expected range of flow velocities and temperatures of a particular application, while simultaneously determining the temperature to distinguish between velocity and temperature changes. To solve this problem, we propose a new measurement method [6] that allows the simultaneous measurement of flow velocity and electrical conductivity by creating a so-called look-up table (LuT).

Keywords: Measurements of flow rates and local velocities; measurement of electrical conductivity; inductive methods

  • Lecture (Conference)
    4th International Workshop on Measuring Techniques for Liquid Metal Flows, 27.-29.05.2024, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38770


Tumour response to hypoxia: understanding the hypoxic tumour microenvironment to improve treatment outcome in solid tumours

Bigos, K.; Quiles, C.; Lunj, S.; Smith, D.; Krause, M.; Troost, E. G. C.; West, C.; Hoskin, P.; Choudhury, A.

Abstract

Hypoxia is a common feature of solid tumours affecting their biology and response
to therapy. One of the main transcription factors activated by hypoxia is hypoxia-
inducible factor (HIF), which regulates the expression of genes involved in various
aspects of tumourigenesis including proliferative capacity, angiogenesis, immune
evasion, metabolic reprogramming, extracellular matrix (ECM) remodelling, and
cell migration. This can negatively impact patient outcomes by inducing
therapeutic resistance. The importance of hypoxia is clearly demonstrated by
continued research into finding clinically relevant hypoxia biomarkers, and
hypoxia-targeting therapies. One of the problems is the lack of clinically
applicable methods of hypoxia detection, and lack of standardisation.
Additionally, a lot of the methods of detecting hypoxia do not take into
consideration the complexity of the hypoxic tumour microenvironment (TME).
Therefore, this needs further elucidation as approximately 50% of solid tumours are
hypoxic. The ECM is important component of the hypoxic TME, and is developed
by both cancer associated fibroblasts (CAFs) and tumour cells. However, it is
important to distinguish the different roles to develop both biomarkers and novel
compounds. Fibronectin (FN), collagen (COL) and hyaluronic acid (HA) are
important components of the ECM that create ECM fibres. These fibres are
crosslinked by specific enzymes including lysyl oxidase (LOX) which regulates
the stiffness of tumours and induces fibrosis. This is partially regulated by HIFs.
The review highlights the importance of understanding the role of matrix
stiffness in different solid tumours as current data shows contradictory results
on the impact on therapeutic resistance. The review also indicates that further
research is needed into identifying different CAF subtypes and their exact roles;
with some showing pro-tumorigenic capacity and others having anti-
tumorigenic roles. This has made it difficult to fully elucidate the role of
CAFs within the TME. However, it is clear that this is an important area of
research that requires unravelling as current strategies to target CAFs have
resulted in worsened prognosis. The role of immune cells within the tumour
microenvironment is also discussed as hypoxia has been associated with
modulating immune cells to create an anti-tumorigenic environment. Which
has led to the development of immunotherapies including PD-L1. These
hypoxia-induced changes can confer resistance to conventional therapies,
such as chemotherapy, radiotherapy, and immunotherapy. This review
summarizes the current knowledge on the impact of hypoxia on the TME
and its implications for therapy resistance. It also discusses the potential of
hypoxia biomarkers as prognostic and predictive indictors of treatment
response, as well as the challenges and opportunities of targeting hypoxia in
clinical trials.

Keywords: hypoxia; tumour microenvironment; extracellular matrix; immune cells; cancer associated fibroblasts

  • Open Access Logo Frontiers in Oncology 14(2024), 1331355

Permalink: https://www.hzdr.de/publications/Publ-38768


Application of Multivariate Tromp Functions for Evaluating the Joint Impact of Particle Size, Shape and Wettability on the Separation of Ultrafine Particles via Flotation

Sygusch, J.; Wilhelm, T.; Furat, O.; Bachmann, K.; Schmidt, V.; Rudolph, M.

Abstract

Froth flotation predominantly separates particles according to their differences in wettability. However, other particle properties such as size, shape or density significantly influence the separation outcome as well. Froth flotation is most efficient for particles within a size range of about 20–200 μm, but challenges arise for very fine or coarse particles that are accompanied by low recoveries and poor selectivity. While the impact of particle size on the separation behavior in flotation is well known by now, the effect of particle shape is less studied and varies based on the investigated zone (suspension or froth) and separation apparatus used. Beyond these complexities, many particle properties are correlated, making it challenging to analyze the isolated impact of individual properties on the separation behavior. Therefore, a multidimensional perspective on the separation process, considering multiple particle properties, enhances the understanding of their collective influence. In this paper, the two-dimensional case is studied; i.e., a parametric modeling approach is applied to determine bivariate Tromp functions from scanning electron microscopy-based image data of the feed and the separated fractions. With these functions it is possible to characterize the separation behavior of particle systems. Using a model system of ultrafine (<10 μm) particles, consisting of either glass spheres or glass fragments with different wettability states as the floatable fraction and magnetite as the non-floatable fraction, allows for the investigation of the influence of descriptor vectors consisting of size, shape and wettability, on the separation. In this way, the present paper contributes to a better understanding of the complex interplay between certain descriptor vectors for the case of ultrafine particles. Furthermore, it demonstrates the benefits of using multivariate Tromp functions for evaluating separation processes and points out the limitations of SEM-based image measurements by means of mineral liberation analysis (MLA) for the studied particle size fraction.

Keywords: Multivariate Tromp function; froth flotation; multidimensional separation; ultrafine particles; particle shape; particle size; particle wettability

Permalink: https://www.hzdr.de/publications/Publ-38762


The crystal structure of (2-diphenylphosphanylphenyl) 2-[7-(dimethylamino)-2-oxochromen-4-yl]acetate, C31H26NO4P

Mamat, C.; Köckerling, M.

Abstract

C31H26NO4P, monoclinic, P21/c (No. 14), a = 16.3835 (2) Å, b = 14.5755 (2) Å, c = 10.5388 (2) Å, β = 95.694 (1) °, V = 2504.22 (7) Å3, Z = 4, Rgt(F) = 0.0435, wRref(F2) = 0.1170, T = 173 (2) K.

Keywords: X ray; Staudinger Ligation; coumarin; fluorescence

Permalink: https://www.hzdr.de/publications/Publ-38761


Flow field tomography identifies and quantifies pore opening and clogging in sandstones

Fischer, C.; Schabernack, J.; Kulenkampff, J.

Abstract

Fluid-rock interactions drive changes in porosity and permeability. This has important consequences for the flow field development in the complex porous material and thus controls the evolution of reactive transport processes. Important applications are in the vast field of reservoir rock alteration, e.g. by coupled dissolution and precipitation processes. While dissolution processes can cause local increases in pore space and permeability, they can also lead to pore throat blockage, which can cause formation damage due to precipitation reactions and particle retention in pore throats. Although these mechanisms are understood in principle, the direct changes in the flow field they cause are difficult to observe directly. Using positron emission tomography (PET), we show how flow field heterogeneities are quantitatively affected by the coupling of dissolution reactions and pore throat blockage by particles in a long-term experiment.
Specifically, we performed a dissolution experiment focusing on calcite cement in sandstones. While dissolution is responsible for a local increase in pore space, mobilized iron oxide and sheet silicate colloids are trapped and cause a local decrease in permeability. Direct comparison of sequences of PET-derived flow field data reveals a pattern of flow field modification during this experiment. PET thus becomes a key analytical tool to localize and quantify pore-scale flow field changes, in addition to recent advances focused on the identification of flow channeling effects of advective flow 1 and on the heterogeneity of diffusive flux in low permeability rocks 2.

1. Pingel, J. L.; Kulenkampff, J.; Jara-Heredia, D.; Stoll, M.; Zhou, W.; Fischer, C.; Schäfer, T., In-situ flow visualization with Geo-Positron-Emission-Tomography in a granite fracture from Soultz-sous-Forêts, France. Geothermics 2023, 111, 102705.
2. Bollermann, T.; Yuan, T.; Kulenkampff, J.; Stumpf, T.; Fischer, C., Pore network and solute flux pattern analysis towards improved predictability of diffusive transport in argillaceous host rocks. Chemical Geology 2022, 606, 120997.

  • Lecture (Conference)
    Interpore 2024, 13.-16.5.2024, Qingdao, China

Permalink: https://www.hzdr.de/publications/Publ-38760


20 years of experience with CW-SRF operation at ELBE

Arnold, A.

Abstract

ELBE is a compact, accelerator-driven photon and particle source. The variety of secondary radiation being offered extends from high-energy gamma rays to infrared and THz radiation as well as from neutrons to positrons and electrons. Since 2001 ELBE is operated as a user facility, providing more than 5500 hours of beamtime with an efficiency of more than 90% each year. The electron accelerator is based on four superconducting 9-cell TESLA cavities that are driven in CW operation to accelerate an average current of 1 mA up to beam energies of 40 MeV. In addition an upgraded version of a superconducting radio-frequency (SRF) photoinjector was brought into operation in 2014. After a period of commissioning, a gradual transfer to routine operation took place in 2017, so that now more than 1800h of user beam are generated by this unique CW electron source every year.

The talk will summarize our experiences of operating all our SRF cavities over two decades in CW. In detail, this includes the cavity performance and attempts to improve it, as well as investigations on their limitations. Additionally, we will discuss several issues that are related to the high average RF as well as beam power and we will present appropriate measures to protect the machine. In this regard we will also introduce a resonant ring for RF component tests at CW power levels up to 100 kW. Regarding the SRF gun, the main emphasis lies in seamlessly integrating a normal-conducting photocathode into the SRF cavity, alongside addressing associated intricacies like dark current, multipacting, and contamination of the resonator.

Keywords: ELBE; CW SRF; TESLA cavity; SRF gun; photo cathode; electron source; injector

Involved research facilities

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  • Lecture (others)
    MAMI Seminar - Seminar über spezielle Probleme der Beschleunigerphysik, 08.02.2024, Mainz, Deutschland
    PURL: https://www.kernphysik.uni-mainz.de/beschleuniger/mami-seminar/

Permalink: https://www.hzdr.de/publications/Publ-38759


Data publication: Analysis of loss of flow without scram test in the FFTF reactor – Thermal hydraulics data

Ponomarev, A.; Nikitin, E.; Fridman, E.

Abstract

Thermal hydraulic system models of the FFTF with the Cycle 8C core for LOFWOS Test #13, created using the ATHLET code, along with the benchmark results (point kinetics and spatial kinetics), sensitivity analyses, cross section data and DYN3D models for coupled DYN/ATHLET calculations.

Keywords: ATHLET; FFTF; Gas Expansion Module; loss of flow; point kinetics; SFR; unprotected transient; spatial kinetics; coupled calculations; DYN3D

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Permalink: https://www.hzdr.de/publications/Publ-38758


Solutal Marangoni force controls lateral motion of electrolytic gas bubbles

Zhang, H.; Ma, Y.; Huang, M.; Mutschke, G.; Zhang, X.

Abstract

Electrochemical gas-evolving reactions have been widely used for industrial energy conversion and storage processes. Gas bubbles form frequently at the electrode surface due to a small gas solubility, thereby reducing the effective reaction area and increasing the over-potential and ohmic resistance. However, the growth and motion mechanisms for tiny gas bubbles on the electrode remains elusive. Combining molecular dynamics (MD) and fluid dynamics simulations (CFD), we show that there exists a lateral solutal Marangoni force originating from an asymmetric distribution of dissolved gas near the bubble. Both MD and CFD simulations deliver a similar magnitude of the Marangoni force of B~0.01 nN acting on the bubble. We demonstrate that this force may lead to lateral bubble oscillations and analyze the phenomenon of dynamic self-pinning of bubbles at the electrode boundary.

Permalink: https://www.hzdr.de/publications/Publ-38757


Phase composition and stability of Gd2-xThxZrO7 under extreme conditions

Svitlyk, V.; Weiß, S.; Gabarono, G.; Hübner, R.; Worbs, A.; Huittinen, N. M.; Hennig, C.

Abstract

Introduction of Th into a hydrothermally synthesized disordered fluorite-type Gd2Zr2O7 phase induces a transition to an ordered pyrochlore-type phase at a Th concentration of 10% at the Gd site (Gd1.8Th0.2ZrO7 composition). Degree of order of the fluorite-type phase reaches 50% for a Th concentration of 25% (Gd1.5Th0.5ZrO7 composition). Upon application of high pressure, the Gd2Zr2O7 phase retains fluorite-type structure until the pressure of 33 GPa (K0 = 167(1) GPa) where it undergoes a reversible amorphisation. The Gd1.7Th0.3ZrO7 phase was found to be stable until at least the pressure of 25 GPa (K0 = 169(3) GPa). Upon heating to Tmax of 1135 K, the Gd2Zr2O7 phase retains disordered fluorite-type structural arrangement (α = 3.03·10-5 K-1). Excellent stability of the Gd2-xThxZrO7 phases under extreme conditions of temperature and pressure makes Gd2Zr2O7 a promising candidate as a host matrix for radioactive species for safe long-term underground storage of nuclear waste.

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Permalink: https://www.hzdr.de/publications/Publ-38754


Data publication: Ultralong-term high-density data storage with atomic defects in SiC

Hollenbach, M.; Kasper, C.; Erb, D.; Bischoff, L.; Hlawacek, G.; Kraus, H.; Kada, W.; Ohshima, T.; Helm, M.; Facsko, S.; Dyakonov, V.; Astakhov, G.

Abstract

Experimental data in OriginPro

Keywords: data storage; silicon carbide; color centers; focused ion beams; cathodoluminescence

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Permalink: https://www.hzdr.de/publications/Publ-38751


Ultralong-term high-density data storage with atomic defects in SiC

Hollenbach, M.; Kasper, C.; Erb, D.; Bischoff, L.; Hlawacek, G.; Kraus, H.; Kada, W.; Ohshima, T.; Helm, M.; Facsko, S.; Dyakonov, V.; Astakhov, G.

Abstract

There is an urgent need to increase the global data storage capacity, as current approaches lag behind the exponential growth of data generation driven by the Internet, social media and cloud technologies. In addition to increasing storage density, new solutions should provide long-term data archiving that goes far beyond traditional magnetic memory, optical disks and solid-state drives. Here, we propose a concept of energy-efficient, ultralong, high-density data archiving based on optically active atomic-size defects in a radiation resistance material, silicon carbide (SiC). The information is written in these defects by focused ion beams and read using photoluminescence or cathodoluminescence. The temperature-dependent deactivation of these defects suggests a retention time minimum over a few generations under ambient conditions. With near-infrared laser excitation, grayscale encoding and multi-layer data storage, the areal density corresponds to that of Blu-ray discs. Furthermore, we demonstrate that the areal density limitation of conventional optical data storage media due to the light diffraction can be overcome by focused electron-beam excitation.

Keywords: data storage; silicon carbide; color centers; focused ion beams; cathodoluminescence

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-38750


Improved automated one-pot two-step radiosynthesis of (S)-[18F]FETrp, a radiotracer for PET imaging of indoleamine 2,3-dioxygenase 1 (IDO1)

Maisonial-Besset, A.; Kryza, D.; Kopka, K.; Levesque, S.; Moreau, E.; Wenzel, B.; Chezal, J.-M.

Abstract

Background: (S)-[18F]FETrp is a promising PET radiotracer for imaging IDO1 activity, one of the main enzymes involved in the tryptophan metabolism that plays a key role in several diseases including cancers. To date, the radiosynthesis of this tryptophan analogue remains highly challenging due to partial racemization occurring during the nucleophilic radiofluorination step. This work aims to develop a short, epimerization-free and efficient automated procedure of (S)-[18F]FETrp from a corresponding enantiopure tosylate precursor.
Results: Enantiomerically pure (S)- and (R)-FETrp references as well as tosylate precursors (S)- and (R)-3 were obtained from corresponding N-Boc-(L and D)-tryptophan in 2 and 4 steps, respectively. Manual optimisation of the radiolabelling conditions resulted in >90% radiochemical conversion with more than 99% enantiomeric purity. Based on these results, the (S)-[18F]FETrp radiosynthesis was fully automated on a SynChrom R&D EVOI module to produce the radiotracer in 55.2 ± 7.5% radiochemical yield, 99.9% radiochemical purity, 99.1 ± 0.5% enantiomeric excess, and molar activity of 53.2 ± 9.3 GBq/mol (n = 3).
Conclusions: To avoid racemisation and complicated purification processes, currently encountered for the radiosynthesis of (S)-[18F]FETrp, we report herein significant improvements, including a versatile synthesis of enantiomerically pure tosylate precursor and reference compound and a convenient one-pot two-step automated procedure for the radiosynthesis of (S)-[18F]FETrp. This optimised and robust production method could facilitate further investigations of this relevant PET radiotracer for imaging IDO1 activity.

Keywords: [18F]FETrp; IDO1; Fluorine-18; Radiochemistry; Radiofluorination; Automation; Racemization-free radiolabelling; Circular dichroism detection

Permalink: https://www.hzdr.de/publications/Publ-38748


Anatomy of localized edge modes in laterally coupled waveguides

Iurchuk, V.; Stienen, S.; Lindner, J.; Kakay, A.

Abstract

We present a systematic micromagnetic study of standing spin-wave modes in infinitely long Permalloy strips with rectangular cross-section. Using a finite-element dynamic-matrix method, we first calculate the eigenfrequencies and the corresponding eigenvectors (mode profiles), as a function of the in-plane magnetic field applied across the strip. The ferromagnetic resonance spectra is computed from the mode profiles, assuming a homogeneous radio-frequency excitation, equivalently to an experimental ferromagnetic resonance measurement. The investigation of the field-dependent mode profiles enables for the classification of the observed resonances, here focusing mostly on the \textit{true edge mode} localized at the vicinity of strip edges. Furthermore, we study the mode localization in pairs of 50-nm-thick Permalloy strips as a function of the strip width and their lateral separation. For closely spaced strips, the spatial profile of the quasi-uniform mode is substantially modified due to a significant hybridization with the edge-localized standing spin-wave modes of the neighbouring strip. We show that a wide-range-tunability of the localized edge-mode resonances can be achieved with a precise control of the magnetostatic coupling between the strips. Extreme sensitivity of the edge mode frequency on the bias field demonstrates a potential of the edge resonances for field sensing. Furthermore, for narrow strips ($\approx$100~nm in width), due to the reduced number of the allowed confined modes, a field-controllable switching between the resonances localized either in the strip center or at the edges of the strips can be achieved.

Keywords: Spin waves; Edge modes; Ferromagnetic resonance; Micromagnetic modeling; Magnetostatic coupling

Permalink: https://www.hzdr.de/publications/Publ-38747


Small-scale functional fatigue of a Ni-Mn-Ga Heusler alloy

Fareed, A.; Rosalie, J. M.; Kar, S.; Fähler, S.; Maaß, R.

Abstract

Functional fatigue of shape-memory alloys is a considerable threat to reliable service of actuation devices. Here, we demonstrate the essentially degradation-free cyclic phase-transformation behavior of Ni-Mn-Ga microcrystals up to one million stress-driven superelastic cycles. Cyclic dissipation amounts to about 1/5 of the bulk counterpart and remains unaffected during cycling, even after the introduction of dislocation structures via plastic straining. Plastic yielding and the transformation stress largely exceed the known bulk values. However, the transformation-stress is found to strongly depend on plastic pre-straining, which suggests that the size-affected transformation stress is sensitive to the initial defect structure and that it can be tuned by a targeted introduction of dislocations. These findings demonstrate the high suitability of Ni-Mn-Ga as a robust shape-memory alloy in small-scale functional device engineering.

Keywords: Functional fatigue; Magnetic shape memory alloys; Deformation

Permalink: https://www.hzdr.de/publications/Publ-38745


Surface-symmetry-driven phenomena in magnetoelectric Cr2O3

Pylypovskyi, O.; Weber, S.; Makushko, P.; Veremchuk, I.; Spaldin, N.; Makarov, D.

Abstract

Antiferromagnetic (AFM) Cr$_2$O$_3$ is a unique collinear magnetoelectric material at room temperature. The bulk properties stemming from its magnetic symmetry render chromia of high interest for fundamentals and applications [1]. Features of the chromia surface remain much less explored. Here, we consider nominally compensated surfaces ($m$~and $a$~planes) of Cr$_2$O$_3$ [2]. We show that they provide a sizeable Dzyaloshinskii--Moriya interaction (DMI) determined by the surface magnetic symmetry point group and quantify it to be about 1\,mJ/m$^2$ by means of \textit{ab initio} and micromagnetic approaches. The DMI leads to the development of nonzero surface magnetization $\vec{M}$ whose sign is uniquely determined by the AFM state. The $m$ and $a$ planes of Cr$_2$O$_3$ behave as the canted ferrimagnet and canted 4-sublattice antiferromagnet, respectively. The coupling of $\vec{M}$ to the direction of the N\'{e}el vector is shown by magnetotransport measurements.

[1] P. Makushko et al., Nat. Comm. 13, 6745 (2022). [2] O.V. Pylypovskyi, S. F. Weber et al., ArXiv:2310.13438 (2023).

Keywords: Cr2O3; antiferromagnetism; single crystal; symmetry

  • Lecture (Conference)
    DPG Spring Meeting, 17.-22.03.2024, Berlin, Germany

Permalink: https://www.hzdr.de/publications/Publ-38738


Probing the Long- and Short-Range Structural Chemistry in the C-Type Bixbyite Oxides Th0.40Nd0.48Ce0.12O1.76, Th0.47Nd0.43Ce0.10O1.785 and Th0.45Nd0.37Ce0.18O1.815 via Synchrotron X-ray Diffraction and Absorption Spectroscopy

Murphy, G. L.; Bazarkina, E.; Svitlyk, V.; Roßberg, A.; Potts, S.; Hennig, C.; Henkes, M.; Kvashnina, K.; Huittinen, N. M.

Abstract

The long- and short- range structural chemistry of the C-type bixbyite compounds Th0.40Nd0.48Ce0.12O1.76, Th0.47Nd0.43Ce0.10O1.785 and Th0.45Nd0.37Ce0.18O1.815 is systematically examined using synchrotron X-ray powder diffraction (S-PXRD), high energy resolution fluorescence detection X-ray absorption near edge (HERFD-XANES) and extended absorption fine structure spectroscopy (EXAFS) measurements supported by electronic structure calculations. S-PXRD measurements revealed the title compounds all form classical C-type bixbyite structures in space group Ia3 ̅ that have disordered cationic crystallographic sites with further observation of characteristic superlattice reflections corresponding to oxygen vacancies. Despite the occurrence of oxygen vacancies, HERFD-XANES measurements on the Ce L3-edge revealed that Ce incorporates as Ce+4 into the structures but involves significant local distortion akin to cluster behavior and loss of nearest-neighbors. In comparison, HERFD-XANES measurements on the Nd+3 L3-edge supported by electronic structure calculations reveal that Nd+3 adopts a local coordination environment similar to the long-range C-type structure whilst providing charge balancing for the formation of oxygen defects. Th L3-edge EXAFS analysis reveals shorter average Th-O distances in the title compounds in comparison to pristine ThO2 in addition to shorter Th-O and Th-Ce distances compared to Th-Th or Ce-Ce in corresponding F-type binary oxides (ThO2 and CeO2). These distances are further found to decrease with the increased Nd content of the structures despite simultaneous observation of the overall lattice structure progressively expanding. Linear combination calculations of the M-O bond lengths are used to explain these observations, where the role of oxygen defects, via Nd+3 incorporation, induces local bond contraction and enhanced Th+4 cation valence leading to the observed increased lattice expansion with progressive Nd+3 incorporation. Overall, the investigation points to the significance of dissimilar cations exhibiting variable short-range chemical behavior and how it can affect long-range structural chemistry of complex oxides.

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-38737


Investigation of cerium as a surrogate for tetravalent actinides in monazite-type compounds

Lender, T.; Bazarkina, E.; Kvashnina, K.; Huittinen, N. M.; Peters, L.

Abstract

The incorporation of tetravalent cerium into the monazite structure via Ca(II)-coupled substitution was investigated using a solid state and a co-precipitation route. Based on powder XRD measurements and elemental mappings an optimised synthesis procedure was developed that averts the formation of secondary phases and allows the stabilisation of tetravalent cerium with a ratio of up to 0.21 Ce(IV)/Ce(III). In-situ HERFD-XANES measurements at the Ce L3 edge at up to 800 °C were performed to study the cerium oxidation state during the phase transformation from rhabdophane to monazite and the sintering process, revealing an unexpected non-linear behaviour as well as a charge-directing effect of the lanthanum cation.

Keywords: monazite; coupled substitution; solid solution; X-ray diffraction; in-situ XANES

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Permalink: https://www.hzdr.de/publications/Publ-38736


Heavy metal stabilization of DNA origami nanostructures

Kemper, U.; Weizenmann, N.; Kielar, C.; Erbe, A.; Seidel, R.

Abstract

DNA origami is a powerful tool to fold 3-dimensional DNA structures with nanometer precision. Its usage, however, is limited as high ionic strength, temperatures below ~60 °C and pH values between 5 to 10 are required to ensure the structural integrity of DNA origami nanostructures. Here, we demonstrate a simple and effective method to stabilize DNA origami nanostructures against harsh buffer conditions using [PdCl4]2-. It provided the stabilization of different DNA origami nanostructures against mechanical compression, temperatures up to 100 °C, double-distilled water and pH values between 4 to 12. Additionally, DNA origami superstructures and bound cargos are stabilized with a yield of 98 %. To demonstrate the general applicability of our approach, we employed our protocol to a Pd metallization procedure at elevated temperatures. In the future, we think that our method opens up new possibilities for applications of DNA origami nanostructures beyond their usual reaction conditions.

Keywords: DNA nanostructures; DNA origami; DNA metal interaction; seeded growth; DNA metallization

Permalink: https://www.hzdr.de/publications/Publ-38734


A didactical dataset to learn supervised classification with candy

Sinichenko, V. A.; Bähr, M.; Maximilian, M.; Philip, N.; Gabriele, N.; Ihor, T.; Jessica, A.; Florian, L. C.; Martina, R.; Franziska, B.; Yashkumar, P. F.; Anna, S.; Satyam, S. G.; Dora, H.; Asma, W.; Nico, B.; Tim, Q.; Muhammad, H. K.; Benjamin, B.; Roland, N.; Laura, M.; Marius, P.; Siddhartha, J.; Tom, G.; Yaqian, Z.; Yan, A.; Lena, S.; Hamdaan, A. F.; Florens, K.; Shayan, P.; Lukas, P.; Steinbach, P.

Abstract

A didactical dataset to learn supervised classification

It was obtained from university level students measuring candy that was mixed and distributed in bowls to them. The goal of this dataset creation was to expose the students to the data taking process. Further, the dataset is meant for classificatio

Keywords: Data Science; machine learning

Permalink: https://www.hzdr.de/publications/Publ-38732


Development of [¹⁸F]AG-120 as radiotracer for the detection by positron emission tomography (PET) of the mutant isocitrate dehydrogenase 1 in glioma:

Toussaint, M.; Lai, T. H.; Dukic-Stefanovic, S.; Teodoro, R.; Arnaud, L.; Maisonial-Besset, A.; Weber, V.; Moldovan, R.-P.; Meister, S.; Pietzsch, J.; Kopka, K.; Juratli, T. A.; Wenzel, B.; Deuther-Conrad, W.

Abstract

Background: Mutations of isocitrate dehydrogenase (IDH) enzymes are frequent alterations in glioma - the most common being the IDH1R132H - and their identification has become essential for patient stratification. Here, we propose a transdisciplinary approach to develop an ¹⁸F-labeled ligand to detect the IDH1R132H protein directly and non-invasively by PET.
Material and Methods: Radiosynthesis was performed using the TRACERlab FX2 N automated radiosynthesizer. In vitro evaluation of inhibitory potency, binding affinity, and cell uptake of [¹⁸F]AG-120 was performed using U251 human glioblastoma cells stably transfected with IDH1 or IDH1R132H. In vivo metabolism was investigated in CD-1 mice, and dynamic PET scans (NanoScan®PET/CT) were performed in nude rats bearing U251-IDH1 or U251-IDH1R132H glioblastoma.
Results: AG-120 shows a high inhibitory potency toward IDH1R132H (IC50=5.11 nM). Diastereomerically pure [¹⁸F]AG-120 was produced by an automated copper-mediated radiofluorination. Internalization studies showed a higher uptake of [18F]AG-120 in U251-IDH1R132H cells compared to that in U251-IDH1 cells (0.4 vs. 0.013% ID/μg protein at 120 min), which was suppressed by self-blocking (0.009% ID/μg protein at 120 min). Excellent metabolic stability in vivo was demonstrated (parent fractions in plasma and brain at 30 min p.i.: 85% and 91%, respectively). Low initial uptake in tumors of both models (TAC-peak value ~0.4 SUV) was observed. A slightly higher retention in IDH1R132H- compared to IDH1-tumors (Tumor-to-Background Ratio[30-60min]: ~1.6 vs. ~1.1) was detected.
Conclusion: We have successfully automated the production of [¹⁸F]AG-120 and gained valuable insights into its interactions with IDH1 and IDH1R132H. [¹⁸F]AG-120 will serve as a reference compound for future evaluations of mIDH inhibitors/radioligands and may have applications in peripheral tumors, such as chondrosarcoma.
Acknowledgements: This work was funded by the the European-Regional-Development-Fund and the Sächsische-Aufbaubank (project no. 100364142). We thank Dr. Jacqueline Kessler and Prof. Dirk Vordermark, Department of Radiotherapy, Martin Luther University Halle-Wittenberg, Halle, Germany, for providing the cells.

Keywords: IDH mutation; Preclinical imaging; ¹⁸F-labeled ligand

  • Lecture (Conference)
    Nuclear Medicine and Neurooncology Symposium: Precision Medicine, 26.-27.04.2024, Vienna, Austria

Permalink: https://www.hzdr.de/publications/Publ-38730


Inductive bubble detection for liquid sodium

Krause, L.; Sieger, M.; Gundrum, T.; Wondrak, T.; Eckert, S.

Abstract

We present an inductive measurement technique for the identification of gas bubbles in liquid metals e.g., liquid sodium as is used as coolant in fast fission reactors. Gas bubbles in the coolant are an indication of damage to the tubing of the steam generator unit and can lead to severe accidents by chemical reactions of the liquid sodium. The contactless inductive bubble detection (CIBD) consists of an excitation coil generating an alternating magnetic field that induces eddy currents in the fluid. Electrically non-conducting gas bubbles in the otherwise conducting fluid act as obstacles to these eddy currents and the slight change of current distribution can be detected outside of the fluid by magnetic field sensors. One sensor is sufficient to verify the existence of gas bubbles robustly and it is possible to estimate the bubble velocity without any calibration. We outline how the use of multiple sensors enables to extract additional quantities of gas bubbles as size and position.

Keywords: Bubble detection; inductive measurement technique; liquid sodium

  • Contribution to proceedings
    Specialist Workshop on Advanced Instrumentation and Measurement Techniques for Nuclear Reactor Thermal-Hydraulics and Severe Accidents (SWINTH-2024), 17.-20.06.2024, Dresden, Deutschland
    Proceedings of the Specialist Workshop on Advanced Instrumentation and Measurement Techniques for Nuclear Reactor Thermal-Hydraulics and Severe Accidents (SWINTH-2024)
  • Lecture (Conference)
    Specialist Workshop on Advanced Instrumentation and Measurement Techniques for Nuclear Reactor Thermal-Hydraulics and Severe Accidents (SWINTH-2024), 17.-20.06.2024, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38726


Inverting the Kohn-Sham equations with physics-informed machine learning

Martinetto, V.; Shah, K.; Cangi, A.; Pribram-Jones, A.

Abstract

This data repository contains the datasets used in the paper "Inverting the Kohn-Sham equations with physics-informed machine learning". 

It contains the data generation scripts, datasets for the systems used in the paper (Single Well - 1D atom, Double Well - 1D diatomic molecule) and output potentials generated by the physics-informed machine learning models (physics-informed neural networks and Fourier neural operators).

Keywords: density functional theory; machine learning

Involved research facilities

  • Data Center

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Permalink: https://www.hzdr.de/publications/Publ-38725


Complexation of Cm(III) and Eu(III) with phosphates: an experimental and theoretical study

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

Abstract

The environmental fate of radionuclides (RN), such as actinides and fission products, disposed of in underground nuclear waste repositories is a major concern. Long-term safety assessments of these disposal sites depend on the ability of geochemical models and thermodynamic databases (TDBs) to predict the mobility of RNs over very long time scales. One example where TDBs still have large data gaps is related to the complexation of trivalent actinides and lanthanides with aqueous phosphates. Indeed, solid phosphate monazites are one of the candidate phases for the immobilization of specific high-level waste streams for future safe storage in deep underground disposal facilities, therefore potentially and locally increasing the presence of phosphate at the final disposal site.

Recent work [1-3] obtained reliable complexation constants at 25 °C and at elevated temperatures and thus, closed some knowledge gaps. Laser-induced luminescence spectroscopy was used to study the complexation of Cm(III) and Eu(III) as a function of total phosphate concentration in the temperature regime 25-90 °C, using NaClO4 as a background electrolyte. These studies have been conducted in the acidic pH-range to avoid precipitation of solid Cm and Eu rhabdophane. In addition to the presence of the CmH2PO4 2+/EuH2PO4 2+ species [1-3], the formation of Cm(H2PO4)2 + [2] and Eu(H2PO4)2 + [3] was unambiguously established from the collected luminescence spectroscopic data. The conditional complexation constants of all aqueous complexes were extrapolated to infinite dilution by applying the Specific ion Interaction Theory. Using the integrated van´t Hoff equation, both the molar enthalpy of reaction ΔrHm° and entropy of reaction ΔrSm° values were derived.

Depending on the concentration of phosphate, monodentate or bidentate Cm(III)/Eu(III)-phosphate complexes form with different overall coordination numbers (8,9), but obtaining such information from spectroscopic data only is often challenging. Thus, the structural properties, electronic structures, and thermodynamics of the 1:1 and 1:2 Cm(III) and Eu(III) phosphate complexes were solved using state-of-the-art relativistic quantum chemical (QC) calculations. In particular, the QC methods allowed i) to investigate the complexation strength of Cm(III) and Eu(III) with aqueous phosphate, ii) to understand the possible change of the coordination number with increasing temperature and iii) to investigate the nature (ionic/covalent) of the Cm/Eu bonds with water and phosphate.

Combining the information obtained from quantum chemical calculations with the observed spectral changes facilitates the decisive determination of the structures of the formed phosphate complexes and their overall coordination [2,3].

References
[1] N. Jordan et al., Inorganic Chemistry 57, 7015 (2018).
[2] N. Huittinen et al., Inorganic Chemistry 60, 10656 (2021).
[3] I. Jessat et al., Inorganic Chemistry (in preparation).

Keywords: europium; curium; complexation; SIT; phosphate; ab initio

  • Contribution to proceedings
    53rd Journées des Actinides, 15.-18.04.2024, Lille, France
  • Lecture (Conference)
    53rd Journées des Actinides, 15.-18.04.2024, Lille, France

Permalink: https://www.hzdr.de/publications/Publ-38724


Retrained Models and Scripts for Aluminum at 298K and 933K

Fiedler, L.; Cangi, A.

Abstract

Retrained Models and Scripts for Aluminum at 298K and 933K

Authors

- Fiedler, Lenz (HZDR/CASUS)
- Cangi, Attila (HZDR/CASUS)

Affiliations:

HZDR - Helmholtz-Zentrum Dresden-Rossendorf
CASUS - Center for Advanced Systems Understanding

Data set description

This data sets contains models, scripts and inference results for aluminum at room temperature and the melting point. Training data, hyperparameters and general methodology follow Ref. [1]. The models here are retrained versions of the ones discussed in this publication, and therefore retrained versions of the models contained in Ref. [2]. As such, data from Ref. [2] has been used. Only a subset of models contained in Ref. [1] have been retrained, namely the room temperature model, one liquid and one solid melting point model with four training snapshot each, and the final melting point hybrid model (six training snapshots per phase). Furthermore, for both the hybrid melting temperature model and the room temperature model, multiple models with different initializations were trained.

All models were trained with the MALA code [3] version 1.2.1. They show better accuracy than their original counterparts, as they were trained using the inter-snapshot shuffling algorithm first discussed for the MALA code in Ref. [4].

[1] - "Accelerating finite-temperature Kohn-Sham density functional theory with deep neural networks", Physical Review B, doi.org/10.1103/PhysRevB.104.035120
[2] - "RODARE", doi.org/10.14278/rodare.2485 (v1.0.0)
[3] - "MALA", Zenodo, doi.org/10.5281/zenodo.5557254
[4] - "Machine learning the electronic structure of matter across temperatures", Physical Review B, doi.org/10.1103/PhysRevB.108.125146

Contents

- The models themselves, labeled as either Al298K or Al933K, given as one .zip file per model
    - For 933K, additionally "liquid", "solid" and "hybrid" denotes the training data set
    - For ensembles, a running index denotes the number in the ensemble
- Inference results, given as a single .zip file
    - For all models, band energy and total free energy results are given in the .csv format
        - The columns in these files correspond to "Calculated via DFT LDOS", "Calculated via ML-DFT LDOS", "Calculated via Kohn-Sham system", respectively
    - For some models, additionally the predicted electronic density and density of states on select snapshots is given
- Shuffling, training and testing scripts, given as a single .zip file
    - Scripts are ready-to-use with suitable MALA installation, however, correct data paths have to be filled in
    
   

Keywords: Data set; DFT

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Permalink: https://www.hzdr.de/publications/Publ-38719


High-field magnetization of KEr(MoO4)2

Kutko, K.; Bernáth, B.; Khrustalyov, V.; Young, O.; Engelkamp, H.; Christianen, P. C. M.; Prodan, L.; Skourski, Y.; Pourovskii, L. V.; Khmelevskyi, S.; Kamenskyi, D.

Abstract

We report a magnetization study of the rare-earth-based paramagnet KEr(MoO4)2 in a magnetic field up to 50 T. A recent observation of massive magnetostriction and rotational magnetocaloric effects in this compound triggered interest in the microscopic mechanism behind these phenomena. We combine several experimental techniques to investigate the magnetization behavior up to its saturation along three main crystallographic directions. The synergy of magnetic torque measurements and vibrating sample magnetometry allowed us to reconstruct parallel and perpendicular components of the magnetization vector, enabling us to trace its evolution up to 30 T. Our experiments reveal the magnetization saturation along all principle axes well below the value, expected from crystal electric field calculations. We argue that an externally applied magnetic field induces a distortion of the local environment of Er3+ ions and affects its crystal electric field splitting.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-38714


Templates of expected measurement uncertainties for neutron-induced capture and charged-particle production cross section observables

Lewis, A. M.; Neudecker, D.; Carlson, A. D.; Smith, D. L.; Thompson, I.; Wallner, A.; Barry, D. P.; Bernstein, L. A.; Block, R. C.; Stephen Croft, Y. D.; Drosg, M.; Haight, R. C.; Herman, M. W.; Young Lee, H.; Otuka, N.; Sjöstrand, H.; Sobes, V.

Abstract

This paper provides a template of expected uncertainties and correlations for measurements
of neutron-induced capture and charged-particle production cross sections. Measurements performed in-
beam include total absorption spectroscopy, total energy detection, gamma-ray spectroscopy, and direct charged-
particle detection. Offine measurements include activation analysis and accelerator mass spectrometry. The
information needed for proper use of the datasets in resonance region and high energy region evaluations is
described, and recommended uncertainties are provided when specific values are not available for a dataset.

Permalink: https://www.hzdr.de/publications/Publ-38712


Templates of expected measurement uncertainties

Neudecker, D.; Lewis, A. M.; Matthews, E. F.; Vanhoy, J.; Haight, R. C.; Smith, D. L.; Talou, P.; Croft, S.; Carlson, A. D.; Pierson, B.; Wallner, A.; Al-Adili, A.; Bernstein, L.; Capote, R.; Devlin, M.; Drosg, M.; Duke, D. L.; Finch, S.; Herman, M. W.; Kelly, K. J.; Koning, A.; Lovell, A. E.; Marini, P.; Montoya, K.; Nobre, G. P. A.; Paris, M.; Pritychenko, B.; Sjöstrand, H.; Snyder, L.; Sobes, V.; Solders, A.; Taieb, J.

Abstract

The covariance committee of CSEWG (Cross Section Evaluation Working Group) estab-
lished templates of expected measurement uncertainties for neutron-induced total, (n,γ), neutron-induced
charged-particle, and (n,xn) reaction cross sections as well as prompt fission neutron spectra, average
prompt and total fission neutron multiplicities, and fission yields. Templates provide a list of what uncer-
tainty sources are expected for each measurement type and observable, and suggest typical ranges of these
uncertainties and correlations based on a survey of experimental data, associated literature, and feedback
from experimenters. Information needed to faithfully include the experimental data in the nuclear-data
evaluation process is also provided. These templates could assist (a) experimenters and EXFOR compilers
in delivering more complete uncertainties and measurement information relevant for evaluations of new
experimental data, and (b) evaluators in achieving a more comprehensive uncertainty quantification for
evaluation purposes. This effort might ultimately lead to more realistic evaluated covariances for nuclear-
data applications. In this topical issue, we cover the templates coming out of this CSEWG effort–typically,
one observable per paper. This paper here prefaces this topical issue by introducing the concept and
mathematical framework of templates, discussing potential use cases, and giving an example of how they
can be applied (estimating missing experimental uncertainties of 235U(n,f) average prompt fission neutron
multiplicities), and their impact on nuclear-data evaluations.

Permalink: https://www.hzdr.de/publications/Publ-38711


Time-resolved nanospectroscopy on Si-doped GaAs-InGaAs core-shell nanowires

Luferau, A.; Obst, M.; Kehr, S.; Eng, L.; Winnerl, S.; Pashkin, O.; Dimakis, E.; Helm, M.

Abstract

High-quality epitaxial nanowires (NWs) based on III-V semiconductors offer the possibility to fabricate ultrafast optical devices due to their direct bandgap and the high electron mobility. Contactless investigation of photoexcited carriers within single NWs is enabled by optical-pump THz-probe scanning near-filed optical microscopy (SNOM) experiment. Here we report on first THz-pump MIR-probe SNOM studies on Si-doped GaAs-InGaAs core-shell NWs utilizing THz radiation from the free-electron laser FELBE. The experiment was carried out with SNOM setup from Neaspec equipped with nanoFTIR module, where a broadband MIR source (5-15μm) serves as a probe. Upon intraband THz-pump (25μm) we observed a red shift of amplitude and phase of the NW plasma resonance, while control interband optical pumping (780nm) induced a blue shift of the resonance, and in both cases an exponential decay with a time constant of 4-5ps is seen. We attribute the blue shift to the contribution of photogenerated carriers. The red shift is assigned to the heating of the electrons in the conduction band and the subsequent increase of the effective mass in the nonparabolic Γ-valley due to high peak electric fields of THz pulses.

Keywords: s-SNOM; nanowires; nanospectroscopy

Involved research facilities

  • F-ELBE
  • Contribution to proceedings
    DPG Spring Meeting of the Condensed Matter Section 2023, 26.03.2023, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-38710


THz-pump / MIR-probe nanospectroscopy on Si-doped GaAs-InGaAs core-shell nanowires

Luferau, A.; Obst, M.; Winnerl, S.; Kehr, S. C.; Dimakis, E.; Pashkin, O.; Kaps, F.; Eng, L. M.; Helm, M.

Abstract

We report on first THz-pump / MIR-probe SNOM studies on Si-doped GaAs-InGaAs core-shell NWs utilizing THz radiation from the free-electron laser FELBE. Upon intraband THz-pump we observe a red shift of the NW plasma resonance in both amplitude and phase spectra, while a controlled interband optical pumping induces a blue shift of the resonance. In both cases, the signal exponentially decays with a time constant of 4-5 ps. We attribute the blue shift to the contribution of photogenerated charge carriers, while the red shift is assigned to the heating of electrons in the conduction band accelerated by the THz electric field of the pump pulses and the subsequent increase of their effective mass due to the nonparabolic Γ-valley dispersion.

Keywords: s-SNOM; nanowires; nanospectroscopy; FEL

Involved research facilities

  • F-ELBE
  • Contribution to proceedings
    2023 48th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 17.09.-31.10.2023, Montreal, Canada

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Permalink: https://www.hzdr.de/publications/Publ-38709


Data publication: Significant Resistance Reduction in Modulation-Doped Silicon Nanowires via Aluminum-Induced Acceptor States in SiO2

Ratschinski, I.; Nagarajan, S.; Trommer, J.; Luferau, A.; Khan, M. B.; Erbe, A.; Georgiev, Y.; Mikolajick, T.; Smith, S. C.; König, D.; Hiller, D.

Abstract

Measured resistance as a function of nanowire (NW) width for different modulation doped Si NWs.

Keywords: electrical properties; modulation doping; resistance; silicon nanowires

Related publications

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Permalink: https://www.hzdr.de/publications/Publ-38708


Significant Resistance Reduction in Modulation-Doped Silicon Nanowires via Aluminum-Induced Acceptor States in SiO2

Ratschinski, I.; Nagarajan, S.; Trommer, J.; Luferau, A.; Khan, M. B.; Erbe, A.; Georgiev, Y.; Mikolajick, T.; Smith, S. C.; König, D.; Hiller, D.

Abstract

Silicon nanowires (Si NWs) like structures in the form of nanosheets are the building blocks for future transistors in the most advanced complementary metal–oxide–semiconductor technologies. However, Si NWs with few nanometers in diameter suffer from severe difficulties with respect to efficient impurity doping. These difficulties can be overcome by a novel doping concept for Si NWs comparable to the modulation doping approach known from III–V semiconductors. Modulation doping means that the parent dopant atoms are spatially separated from the volume that is to be doped by embedding them into an adjacent material with a higher bandgap. Herein, Al-doped SiO2 shells around the Si NWs are used for the experimental realization of modulation doping. In two independent experiments, a significant reduction of the electrical resistance of Si NWs by several orders of magnitude is measured, when compared to the resistance of Si NWs with undoped SiO2 shells. The results are discussed in the context of modulation doping by the surface functionalization with SiO2:Al shells.

Keywords: electrical properties; modulation doping; resistance; silicon nanowires

Related publications

Permalink: https://www.hzdr.de/publications/Publ-38707


Data publication: A quantitative analysis of the effect of box size in N-body simulations of the matter power spectrum

Eingorn, M.; Yilmaz, E.; Yukselci, A. E.; Zhuk, O.

Abstract

The dataset consists of the matter power spectra at four redshifts (z=80,50,15,0) generated by simulating Lambda-Cold Dark Matter cosmology within the cosmic screening approach as described in the associated paper. Outputs of six distinct runs are available for boxes with L= 280, 560, 1680, 4480, 5120, 5632 Mpc/h comoving sizes, each with 2 Mpc/h resolution.

Keywords: inhomogeneous Universe; large-scale structure; cosmic screening; cosmological perturbations; N-body simulations; power spectrum

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Permalink: https://www.hzdr.de/publications/Publ-38704


Analyse, Planung und Umsetzung einer verteilten Informationsarchitektur für ein New Work Konzept am HZDR

Schwabe, J.

Abstract

Im Zuge der zunehmenden Digitalisierung bleibt auch die Arbeitswelt von Veränderungen auf diesem Gebiet nicht unberührt.
Wechselnde Arbeitszeitmodelle und flexible sowie hybride Arbeitsplätze stellen eine Herausforderung für das klassische Flächenmanagement und die Erreichbarkeit von Mitarbeitenden dar.
Um eine veränderliche Belegung von Büroräumen für Beschäftigte zu vereinfachen, werden zunehmend verschiedene Smart Office Solutions entwickelt.
Dazu zählt auch eine flexible Informationsanzeige, um Mitarbeitende auch bei zeitlich und räumlich wechselnden Arbeitsplätzen auffinden zu können.
Am Beispiel eines am Helmholtz-Zentrum Dresden - Rossendorf (HZDR) neu entstehenden Bürogebäudes wird im Rahmen dieser Arbeit ein verteiltes Informationssytem konzipiert und ein Prototyp dessen mit den Basis-Funktionalitäten implementiert.
Dabei kommuniziert ein digitales, kabelloses Türschild in einem drahtlosen Netzwerk mit einem zentralen Server, welcher Informationen aus bestehenden Datenbanken zu aktuellen Raumbelegungen ausliest.
Diese Informationen werden automatisiert auf dem ePaper-Display des Türschildes angezeigt.
Im Vordergrund steht dabei ein möglichst geringer Energiebedarf der über eine mobile Spannungsquelle mit Strom zu versorgenden Türschilder.

Keywords: Data Science; Data Management; Electronic Door Sign; E-Paper; New Work; Smart Office; Python; Arduino; ESP8266

Related publications

  • Bachelor thesis
    Berufsakademie Sachsen, Staatliche Studienakademie Dresden, 2023
    Mentor: Dr.-Ing. Oliver Knodel, Dr. rer. nat. Dietbert Gütter

Permalink: https://www.hzdr.de/publications/Publ-38703


Years: 2024 2023 2022 2021 2020 2019 2018 2017 2016


Pages: [1.] [2.] [3.] [4.] [5.] [6.] [7.] [8.] [9.] [10.] [11.] [12.] [13.] [14.] [15.] [16.] [17.] [18.] [19.] [20.] [21.] [22.] [23.] [24.] [25.] [26.] [27.] [28.] [29.] [30.] [31.] [32.] [33.] [34.] [35.] [36.] [37.] [38.] [39.] [40.] [41.] [42.] [43.] [44.] [45.] [46.] [47.] [48.] [49.] [50.] [51.] [52.] [53.] [54.] [55.] [56.] [57.] [58.] [59.] [60.] [61.] [62.] [63.] [64.] [65.] [66.] [67.] [68.] [69.] [70.] [71.] [72.] [73.] [74.] [75.] [76.] [77.] [78.] [79.] [80.] [81.] [82.] [83.] [84.] [85.] [86.] [87.] [88.] [89.] [90.] [91.] [92.] [93.] [94.] [95.] [96.] [97.] [98.] [99.] [100.] [101.] [102.] [103.] [104.] [105.] [106.] [107.] [108.] [109.] [110.] [111.] [112.] [113.] [114.] [115.] [116.] [117.] [118.] [119.] [120.] [121.] [122.] [123.] [124.] [125.] [126.] [127.] [128.] [129.] [130.] [131.] [132.] [133.] [134.] [135.] [136.] [137.] [138.] [139.] [140.] [141.] [142.] [143.] [144.] [145.] [146.] [147.] [148.] [149.] [150.] [151.] [152.] [153.] [154.] [155.] [156.] [157.] [158.] [159.] [160.] [161.] [162.] [163.] [164.] [165.] [166.] [167.] [168.] [169.] [170.] [171.] [172.] [173.] [174.] [175.] [176.] [177.] [178.] [179.] [180.] [181.] [182.] [183.] [184.] [185.] [186.] [187.] [188.] [189.] [190.] [191.] [192.] [193.] [194.] [195.] [196.] [197.] [198.] [199.] [200.] [201.] [202.] [203.] [204.] [205.] [206.] [207.] [208.] [209.] [210.] [211.] [212.] [213.] [214.] [215.] [216.] [217.] [218.] [219.] [220.] [221.] [222.] [223.] [224.] [225.] [226.] [227.] [228.] [229.] [230.] [231.] [232.] [233.] [234.] [235.] [236.] [237.] [238.] [239.] [240.] [241.] [242.] [243.] [244.] [245.] [246.] [247.] [248.] [249.] [250.] [251.] [252.] [253.] [254.] [255.] [256.] [257.] [258.] [259.] [260.] [261.] [262.] [263.] [264.] [265.] [266.] [267.] [268.] [269.] [270.] [271.] [272.] [273.] [274.] [275.] [276.] [277.] [278.] [279.] [280.] [281.] [282.] [283.] [284.] [285.] [286.] [287.] [288.] [289.] [290.] [291.] [292.] [293.] [294.] [295.] [296.] [297.] [298.] [299.] [300.] [301.] [302.] [303.] [304.] [305.] [306.] [307.] [308.] [309.] [310.] [311.] [312.] [313.] [314.] [315.] [316.] [317.] [318.] [319.] [320.] [321.] [322.] [323.] [324.] [325.] [326.] [327.] [328.] [329.] [330.] [331.] [332.] [333.] [334.] [335.] [336.] [337.] [338.] [339.] [340.] [341.] [342.] [343.] [344.] [345.] [346.] [347.] [348.] [349.] [350.] [351.] [352.] [353.] [354.] [355.]