Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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41356 Publications

Possible Eliashberg-Type Superconductivity Enhancement Effects in a Two-Band Superconductor MgB2 Driven by Narrow-Band THz Pulses

Sobolev, S.; Lanz, A. P.; Dong, T.; Pokharel, A.; Kabanov, V.; Xu, T.-Q.; Wang, Y.; Gan, Z.-Z.; Shi, L.-Y.; Wang, N.-L.; Pashkin, O.; Uykur, E.; Winnerl, S.; Helm, M.; Demsar, J.

We study THz-driven condensate dynamics in epitaxial thin films of MgB2, a prototype two-band superconductor (SC) with weak interband coupling. The temperature and excitation density dependent dynamics follow the behavior predicted by the phenomenological bottleneck model for the single-gap SC, implying adiabatic coupling between the two condensates on the ps timescale. The amplitude of the THz-driven suppression of condensate density reveals an unexpected decrease in pair-breaking efficiency with increasing temperature—unlike in the case of optical excitation. The reduced pair-breaking efficiency of narrow-band THz pulses, displaying minimum near ≈0.7  Tc, is attributed to THz-driven, long-lived, nonthermal quasiparticle distribution, resulting in Eliashberg-type enhancement of superconductivity, competing with pair breaking.

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Permalink: https://www.hzdr.de/publications/Publ-37757
Publ.-Id: 37757


Investigation of microalgae and bubble interaction in electroflotation via image processing

Marquardt, T.; Schwarzenberger, K.; Krujatz, F.; Eckert, K.

Microalgae are becoming increasingly important for numerous applications such as food or pharmaceutical products. Flotation is an effective and comparatively inexpensive process for dewatering of the algal biomass after cultivation. In electroflotation, the hydrophobic algal cells attach to the surface of rising gas bubbles generated by water electrolysis and can be removed as a concentrated froth. For enhanced floatability, the size of microalgae can be increased by flocculation, e.g., with chitosan. Chitosan is a non-toxic, non-contaminating biopolymer that has proven to be a practical flocculant for microalgae. The effectiveness of the flotation process is influenced by numerous variables. At the same time, the mechanisms of the attachment of the algae to the bubbles are not fully understood. Hence, the aim of the presented work is to gain a deeper insight into the processes involved in the electroflotation of microalgae, like the algae-bubble-interaction, using optical measurement methods and machine learning (ML) based image processing.
A main focus is on the number and size of bubbles generated by electrolysis, as well as the size of Chlorella vulgaris agglomerates created by flocculation with chitosan. The properties of the bubbles were influenced by changing the electrolysis voltage and evaluated by image processing methods on microscopic images. Using laser diffraction spectroscopy, the influence of different chitosan dosages and flocculation times on the agglomerate size were analyzed. The size distribution is found to depend strongly on the varying biological properties of the microalgal suspension. Nevertheless, some general recommendations for an optimal chitosan concentration range could be deduced. In order to identify conditions promoting a successful attachment of algae to bubbles, an ML based method using series of microscopic images for visualization of the rising bubble and agglomerate paths during bubble-algal interaction was developed. The results show that a similar size of bubble and microalgal agglomerate is beneficial for enhanced bubble-algae interaction. For the analyzed voltage range, the mean bubble size was approximately 20 μm. The flocculation experiments showed that agglomerate sizes of 20 μm or higher are also achievable and thus, the microalgae flocs can be tuned to a well-floatable size range. Summing up, it was possible to derive first conclusions on how to promote effective electroflotation of microalgae. The developed visualization method contributes to a better understanding of flotation mechanisms and can be used as a basis for further research.

Keywords: Electroflotation; Microalgae; Image Processing; Flocculation; Rising Bubbles

  • Lecture (Conference)
    93rd Annual Meeting of the International Association of Applied Mathematics and Mechanics, 30.05.-02.06.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37756
Publ.-Id: 37756


Evaluating Iron Ore Characteristics through Machine Learning and 2D LiDAR Technology

Matos, S.; Pinto, T.; Domingues, J.; Ranieri, C.; Albuquerque, K.; Moreira, V.; Souza, E.; Ueyama, J.; Melo Euzebio, T. A.; Pessin, G.

Conveyor belts are the most effective way to transport ore in a mining complex. The ore that comes from the mining areas can be heterogeneous in size and type. As the ore needs to pass through several processing steps, online information about the ore’s type and degree of fragmentation can help improve mineral processing for both safety and efficiency. Current instrumentation systems are expensive and require frequent calibration and maintenance. This paper presents a novel intelligent instrument for online recognition of type and degree of fragmentation. A 2D LiDAR sensor and machine learning techniques were used to estimate the characteristics of iron ore particles on conveyor belts. An experiment was conducted using several types of ore and granulometry. Five machine learning models were compared using statistical methods, including analysis of average accuracy and normality and hypotheses tests. Among them, the Random Forest models achieved the highest average accuracy, 93.81% for ore type and 85.52% for the degree of fragmentation. These models were improved by a voting mechanism, resulting in a reduction of classification errors of 93.3% for ore type and 99.2% for the degree of fragmentation. These findings demonstrate potential for improving mineral processing controls and elevating operational safety within the mining sector.

Keywords: Light Detection and Ranging; Conveyor Belt; Machine Learning; Mining Industry

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  • Secondary publication expected from 13.12.2024

Permalink: https://www.hzdr.de/publications/Publ-37754
Publ.-Id: 37754


Data publication: Unraveling dispersion and buoyancy dynamics around radial A + B → C reaction fronts: microgravity experiments and numerical simulations.

Stergiou, Y.; Escala Vodopivec, D.; Papp, P.; Horváth, D.; Hauser, M.; Brau, F.; de Wit, A.; Tóth, Á.; Eckert, K.; Schwarzenberger, K.

This dataset includes the image data obtained from the Sounding Rocket experiment (TEXUS 57) and numerical simulation data.

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Permalink: https://www.hzdr.de/publications/Publ-37753
Publ.-Id: 37753


µCT data of two drill cores of fractured crystalline rock (Grimsel)

Kulenkampff, J.
DataCollector: Loesel, Dagmar; DataCollector: Schoessler, Claudia; Researcher: Jankovsky, Filip; Researcher: Zuna, Milan

Two crystalline rock drill cores from the Grimsel site were scanned with a Nikon XT H 225 - scanner. The samples were prepared (formatted and cast in epoxy) by UJV Rez, Czech Republic. The CT-data were acquired and processed at HZDR-FWOT.

Sample 1 (GAM_UJV_1C_1) contains a complex system of interconnected fractures.
Sample 2 (GAM_UJV_1C_2) contains one single end-to-end fracture with larger aperture.

Size of both samples: Diameter 80 mm, length 165 mm.

Two tomograms were acquired for both samples:
1) Complete drill core as one scan, voxel size ca. 75 µm.
2) HR-tomogram merged from three sections with maximum resolution, voxel size ca. 40 µm.

The tomograms were stored as 3D-raw files. Data format, acquisition parameters, and processing workflow, are documented in the tomogram header files (nrrd-format (text):  see https://teem.sourceforge.net/nrrd/format.html).
This data format is importable into open-source visualization programs as 3D slicer (https://www.slicer.org) or Paraview (https://www.paraview.org). The data processing has been conducted with Avizo (https://www.thermofisher.com/de/de/home/electron-microscopy/products/software-em-3d-vis/avizo-software.html).

Files:
Sample 1
GAM_UJV_1C_1_complet-2_01_NLM: Graylevel image of complete sample, ring artifact removal, non-local-means filter
GAM_UJV_1C_1_complet-2_01_thresholded: Tentative label image of complete sample, threshold segmentation with manual edit
Merged-GAM_UJV_1C_1_HR.Frac_section: Graylevel image of merged fracture section, unfiltered
Merged-GAM_UJV_1C_1_HR.Frac_section.Threshold: Tentative label image of merged fracture section, adaptive threshold segmentation with manual edit
GAM_UJV_1C_1_complet_2.png: Figure of complete sample 
GAM_UJV_1C_1_HR_Frac_Y2.png: Figure of merged high-resolution tomogram

Sample 2
GAM_UJV_1C_2_complet_01.filtered: Graylevel image of complete sample, ring artifact removal, non-local-means filter
GAM_UJV_1C_2_complet_01.filtered.thresholded: Tentative label image of complete sample,  threshold segmentation with manual edit
Merged-GAM_UJV_1C_2_A_01.Frac_section.filtered: Graylevel image of merged fracture section, ring artifact removal, non-local-means filter
Merged-GAM_UJV_1C_2_A_01.Frac_section.filtered.segm: Tentative label image of merged fracture section, threshold segmentation with manual edit
GAM_UJV_1C_2_complett_2.png: Figure of complete sample
GAM_UJV_1C_2_HR_Frac_Y2.png: Figure of merged high-resolution tomogram

Original acquistion data are stored on the HZDR bulk data storage system and available for reprocessing on request.


Financial support was granted from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 847593 (EURAD, WP FUTURE, task 2.2).
 

Keywords: X-ray computed tomography; crystalline rock; granite; drill core; fracture

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Permalink: https://www.hzdr.de/publications/Publ-37750
Publ.-Id: 37750


A Monte Carlo photonic model to simulate the UV inactivation of airborne microorganisms

Cavagnola, M. A.; Hampel, U.; Lecrivain, G.

The goal is to develop a model based on a photonic approach that allows us to track each of the flowing airborne microorganisms and predict, by using a kinetic Monte Carlo algorithm, whether it is active or not

  • Poster
    DLR GANDALF - Graduate School, 26.10.2023, Köln, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37748
Publ.-Id: 37748


Magneto-structural phase transitions for direct magnetic patterning

Bali, R.; Potzger, K.; Lindner, J.; Faßbender, J.

The use of focused ion beams for sensitively controlling the intrinsic magnetic as well as transport properties at the nanoscale requires materials, wherein small atomic displacements results in large property changes. Typical examples are binary alloys consisting of a 3d metal such as Fe and elements such as Al [1], Rh [2] and most recently, V [3]. These materials act as non-ferromagnetic templates onto which atomic reordering within confined regions can be used to realize the direct writing of ferromagnetism. These alloys are deployed as prototypes for exploring nanoscale ion-induced property modulation.

The type of phase transition may vary, for instance, a transition in the chemical order of Fe60Al40 in contrast with the emergence of a crystalline lattice from a short-range ordered structure in Fe60V40. Due to chemical disordering, the localized ferromagnetic in the former alloy imparts spin scattering that can be observed in the anomalous Hall effect, whereas in the latter, the lattice reordering propagates in a layer like fashion providing homogenous ferromagnetic layers. The phase transition characteristics influence their potential applications, such as in ferromagnetic resonance and transport.

Observations of the evolving nearest-neighbour environment of atoms as a function of the atomic displacements helps unravel some of the microscopic processes leading to the large intrinsic property changes. This current research is being performed with the help of large-scale facilities, such as the Ion-Beam-Centre as well as the ELBE at HZDR.

References:

1. S. Sorokin et al., New J. Phys. (2023).
2. W. Griggs et al., APL Materials (2020) 8, 121103.
3. Md. S. Anwar et al., ACS Appl. Elec. Mater. (2022) 4, 8, 3860.

Keywords: ion irradiation; magnetism; magnetic patterning; structural phase transition

Related publications

  • Invited lecture (Conferences)
    7th International Conference on Nanostructuring by Ion Beams (ICNIB 2023), 02.-04.11.2023, Dehradun, Indien

Permalink: https://www.hzdr.de/publications/Publ-37747
Publ.-Id: 37747


Systematic investigation of the Pygmy Dipole Resonance near the magic N = 82 shell closure

Kluwig, F.; Müscher, M.; Savran, D.; Schwengner, R.; Schüttler, T.; Zilges, A.

The Pygmy Dipole Resonance is part of the electric dipole response of an atomic nucleus. There are still several open questions concerning, e.g., its structure. Systematic studies are crucial to improve the knowledge of this excitation mode. Such systematic studies have already been performed along the magic N = 82
isotonic chain using the Nuclear Resonance Fluorescence (NRF) technique, hinting to a trend of increasing strength with increasing N/Z ratio. Comparing these results to those from further NRF experiments on neighbouring non-magic isotopes and on 142Ce, a more fragmented strength distribution seems to occur.

Keywords: Nuclear structure; Dipole excitations; Nuclear resonance fluorescence; Photon scattering; Gamma-ray spectroscopy

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Permalink: https://www.hzdr.de/publications/Publ-37745
Publ.-Id: 37745


Dipole excitations in open shell nuclides near the neutron threshold energy from (g,g') experiments: The case of Ge isotopes

Benouaret, N.; Schwengner, R.; Massarczyk, R.; Shizuma, T.; Bemmerer, D.; Beyer, R.; Junghans, A.; Wagner, A.

The dipole response of the open-shell nuclide 70Ge has been investigated in high-resolution (g,g') experiments using bremsstrahlung produced with electron beams of energies of 8.5 and 14.7 MeV at the linear accelerator ELBE. A resonance-like structure of levels mostly with spin J = 1 has been identified, distributed between 5 MeV up to neutron separation energy Sn as in the case of 76Ge and in contast to 74Ge where the level density is lower and ceases abruptly at about 1 MeV below Sn . The distibution strength was complemented by the unresolved levels using simulations of statistical gamma-ray cascades, corrected by estimations of branching transitions. The summed strength in 70 Ge, completed by the data from 74,76Ge do not fit with a linear trend as function
of the neutron excess. Such unexpected behaviour might be related to the nuclear deformation which seems to play the major role in the moderately deformed germanium isotopic chain.

Keywords: Nuclear structure; Dipole excitations; Photon scattering; Nuclear resonance fluorescence; Gamma-ray cascades

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Permalink: https://www.hzdr.de/publications/Publ-37744
Publ.-Id: 37744


UQTestFuns: A Python3 Library of Uncertainty Quantification (UQ) Test Functions

Wicaksono, D. C.; Hecht, M.

UQTestFuns is an open-source Python3 library of test functions commonly used within the applied uncertainty quantification (UQ) community. Specifically, the package provides:

  • an implementation with minimal dependencies (i.e., NumPy and SciPy) and a common interface of many test functions
  • single entry point collecting test functions and their probabilistic input specifications in a single Python package
  • an opportunity for an open-source contribution, supporting the implementation of new test functions or posting reference results.

In short, UQTestFuns is an homage to the Virtual Library of Simulation Experiments (VLSE).

v0.4.1 includes one additional test function used in the context of metamodeling. The package documentation has been updated following the review process during the submission to the Journal of Open Source Software (JOSS). This release is part of the acceptance of the package to JOSS.

This archive is part of the archival process to ROBIS.

Keywords: python; uncertainty-quantification; benchmark; sensitivity-analysis; metamodeling; reliability-analysis

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Permalink: https://www.hzdr.de/publications/Publ-37736
Publ.-Id: 37736


UQTestFuns: A Python3 library of uncertainty quantification (UQ) test functions

Wicaksono, D. C.; Hecht, M.

Researchers are continuously developing novel methods and algorithms in the field of applied uncertainty quantification (UQ).
During the development phase of a novel method or algorithm, researchers and developers often rely on test functions taken from the literature for validation purposes.
Afterward, they employ these test functions as a fair means to compare the performance of the novel method against that of the state-of-the-art methods in terms of accuracy and efficiency measures.

UQTestFuns is an open-source Python3 library of test functions commonly used within the applied UQ community.
Specifically, the package provides:

  • an implementation with minimal dependencies (i.e., NumPy and SciPy) and a common interface of many test functions available in the UQ literature
  • a single entry point collecting test functions and their probabilistic input specifications in a single Python package
  • an opportunity for an open-source contribution, supporting the implementation of new test functions and posting reference results.

UQTestFuns aims to save the researchers' and developers' time from having to reimplement many of the commonly used test functions themselves.

Keywords: test functions; benchmark; uncertainty quantification; metamodeling; surrogate modeling; sensitivity analysis; reliability analysis; rare event estimation

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Permalink: https://www.hzdr.de/publications/Publ-37735
Publ.-Id: 37735


DAG Optimizations for Feynman Diagrams of High-Multiplicity Scattering Processes in Julia

Reinhard, A.; Ehrig, S.; Hernandez Acosta, U.; Widera, R.

The description of scattering processes in high-energy physics is usually done with Feynman Diagrams. The number of Feynman Diagrams that can be generated for a given process explodes factorially with the number of particles. We discuss a possible approach enabling the calculation of higher-multiplicity scattering processes. We propose representing the calculation for a process as a directed acyclic graph (DAG) of small computation tasks. Using Julia, we can optimize this graph using subgraph replacement strategies together with an optimization algorithm. Finally, efficient code targeting arbitrary heterogeneous HPC systems can be generated from the optimized DAG.

Keywords: Julia; Scattering Processes; Compton; High-Energy Physics; DAG; Optimization; HPC

  • Open Access Logo Lecture (Conference)
    JuliaHEP 2023 Workshop, 06.-09.11.2023, Erlangen Centre for Astroparticle Physics, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-37734
Publ.-Id: 37734


Tunable room-temperature non-linear Hall effect from the surfaces of elementary bismuth thin films

Makarov, D.

In this presentation I will describe our recent experiments with polycrystalline Bi thin films, where we observed non-linear Hall effect.

Keywords: Bi thin films; non-linear Hall effect; geometric non-linear Hall effect

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  • Invited lecture (Conferences) (Online presentation)
    Annual meeting of the Lu Jiaxi international team, 25.-26.11.2023, Ningbo, China

Permalink: https://www.hzdr.de/publications/Publ-37733
Publ.-Id: 37733


Magnetic composites: from printed, self-healable and eco-sustainable magnetoelectronics to smart magnetic soft robots

Makarov, D.

In this lecture for magnetism students, I will cover the following topics: magnetic composites (i.e., mixtures of polymers and magnetic particles); flexible magnetoelectronics; printed magnetoelectronics; eco-sustainable magnetics; magnetic actuation (including locomotion). The aim is to provide an overview of new application scenarios of magnetic materials prepared in the form of composites for hingeless ultrafast actuators and printed magnetic field sensors. The lecture should stimulate activities on the realization of eco-sustainable magnetics including biodegradable and biocompatible magnetic field sensors.

Keywords: flexible magnetic field sensors; shapeable magnetoelectronics; printed magnetoelectronics; magnetic composites

Related publications

  • Invited lecture (Conferences)
    PETASPIN 2023 School on “Spintronics: fundamentals and applications” – II edition, 12.-15.12.2023, Messina, Italy

Permalink: https://www.hzdr.de/publications/Publ-37732
Publ.-Id: 37732


Floquet analysis of a superradiant many-qutrit refrigerator

Kolisnyk, D.; Queißer, F.; Schaller, G.; Schützhold, R.

We investigate superradiant enhancements in the refrigeration performance in a set of N three-level systems that are collectively coupled to a hot and a cold thermal reservoir and are additionally subject to collective periodic (circular) driving. Assuming the system-reservoir coupling to be weak, we explore the regime of stronger periodic driving strengths by comparing collective weak-driving, Floquet-Lindblad, and Floquet-Redfield master equations. We identify regimes where the power injected by the periodic driving is used to pump heat from the cold to the hot reservoir and derive analytic sufficient conditions for them based on a cycle analysis of the Floquet-Lindblad master equation. In those regimes, we also argue for which parameters collective enhancements like a quadratic scaling of the cooling current with N can be expected and support our arguments by numerical simulations.

Keywords: Floquet theory; periodic driving; refrigeration; superradiance; cooling condition; collective effects

Permalink: https://www.hzdr.de/publications/Publ-37731
Publ.-Id: 37731


Sequential Kibble-Zurek dynamics in the anisotropic Ising model of the Si(001) surface

Schaller, G.; Queißer, F.; Parya Katoorani, S.; Brand, C.; Kohlfürst, C.; Freeman, M. R.; Hucht, A.; Kratzer, P.; Sothmann, B.; Horn-Von Hoegen, M.; Schützhold, R.

As a simplified description of the non-equilibrium dynamics of buckled dimers on the Si(001) surface, we consider the anisotropic 2D Ising model and study the freezing of spatial correlations during a cooling quench across the critical point. The dependence of the frozen correlation lengths ξ‖ and ξ⊥ on the cooling rate obtained numerically matches the Kibble-Zurek scaling quite well. However, we also find that the ratio ξ‖/ξ⊥ of their frozen values deviates significantly from the ratio in equilibrium. Supported by analytical arguments, we explain this difference by the fact that the deviation from equilibrium in the weakly coupled direction occurs earlier than in the strongly coupled direction.

Keywords: Kibble-Zurek mechanism; defect formation; temperature quench; silicon surface; Ising model; anisotropy effects

Permalink: https://www.hzdr.de/publications/Publ-37730
Publ.-Id: 37730


How small can Maxwell's demon be? -- Lessons from autonomous electronic feedback models

Schaller, G.

External piecewise-constant feedback control can modify energetic and entropic balances, allowing in extreme scenarios for Maxwell demon operational modes. Without specifying the actual implementation of external feedback loops, one can only partially quantify the additional contributions to entropy production. This is different in autonomously operating systems with internal feedback. Traditional (bipartite) autonomous systems can be divided into controller and a controlled subsystem, but also non-bipartite systems can accomplish the same task. We consider examples of autonomous three-terminal models that transfer heat mainly from a cold to a hot reservoir by dumping a small fraction of it to an ultra-cold (demon) reservoir, such that their coarse-grained dynamics resembles an external feedback loop. We find that the minimal three-level implementation is most efficient in utilizing heat dissipation to change the entropy balance of the effective controlled system.

Keywords: Maxwell demon; autonomous operation; refrigerator; coarse-graining

Permalink: https://www.hzdr.de/publications/Publ-37729
Publ.-Id: 37729


Supporting microscope images: The Impact of Al2O3 Particles from Grit-Blasted Ti6Al7Nb (Alloy) Implant Surfaces on Biocompatibility, Aseptic Loosening, and Infection

Kocjančič, B.; Avsec, K.; Šetina Batič, B.; Feizpour, D.; Godec, M.; Kralj Iglič, V.; Podlipec, R.; Cor, A.; Debeljak, M.; Grant T., J.; Jenko, M.; Dolinar, D.

Supporting confocal fluorescence microscope images of live cells grown on different implant surfaces

Keywords: Ti6Al7Nb implant alloy cementless hip endoprostheses; roughness; Al2O3 grit blasting; surface and subsurface implant contamination; cytotoxicity; aseptic loosening; infection; osteointegration

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Permalink: https://www.hzdr.de/publications/Publ-37728
Publ.-Id: 37728


The Impact of Al2O3 Particles from Grit-Blasted Ti6Al7Nb (Alloy) Implant Surfaces on Biocompatibility, Aseptic Loosening, and Infection

Kocjančič, B.; Avsec, K.; Šetina Batič, B.; Feizpour, D.; Godec, M.; Kralj Iglič, V.; Podlipec, R.; Cor, A.; Debeljak, M.; Grant T., J.; Jenko, M.; Dolinar, D.

For the improvement of surface roughness, titanium joint arthroplasty (TJA) components are grit-blasted with Al2O3 (corundum) particles during manufacturing. There is an acute concern, particularly with uncemented implants, about polymeric, metallic, and corundum debris generation and accumulation in TJA, and its association with osteolysis and implant loosening. The surface morphology, chemistry, phase analysis, and surface chemistry of retrieved and new Al2O3 grit-blasted titanium alloy were determined with scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and confocal laser fluorescence microscopy, respectively. Peri-prosthetic soft tissue was studied with histopathology. Blasted retrieved and new stems were exposed to human mesenchymal stromal stem cells (BMSCs) for 7 days to test biocompatibility and cytotoxicity. We found metallic particles in the peri-prosthetic soft tissue. Ti6Al7Nb with the residual Al2O3 particles exhibited a low cytotoxic effect while polished titanium and ceramic disks exhibited no cytotoxic effect. None of the tested materials caused cell death or even a zone of inhibition. Our results indicate a possible biological effect of the blasting debris; however, we found no significant toxicity with these materials. Further studies on the optimal size and properties of the blasting particles are indicated for minimizing their adverse biological effects.

Keywords: Ti6Al7Nb implant alloy cementless hip endoprostheses; roughness; Al2O3 grit blasting; surface and subsurface implant contamination; cytotoxicity; aseptic loosening; infection; osteointegration

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Permalink: https://www.hzdr.de/publications/Publ-37725
Publ.-Id: 37725


Challenges of the copper-mediated radiofluorination

Kaur, S.; Wenzel, B.; Deuther-Conrad, W.; Dukic-Stefanovic, S.; Toussaint, M.; Kopka, K.; Moldovan, R.-P.

Ziel: Copper-mediated radiofluorination (CMRF) was a breakthrough of the last decade in the development of non-activated 18F-aryl-bearing radiopharmaceuticals.1 Despite extensive studies and improvements of the radiolabelling conditions, the formation of H-side product 3 and OH-side product 4 still possess a challenge in these Suzuki/Stille type reactions. In our work, we faced similar problems and additionally, the continuous hydrolysis of the boronic ester precursor 1 during the semi-preparative HPLC purification resulted in another impurity 5. In this study, we tried to address and overcome these challenges.

Methoden: The CMRF of 1 bearing a non-activating aromatic substituent at para position was optimized by varying the following parameters: solvent (DMA and DMI), reaction time (5 - 20 min), temperature (110 - 130 °C) and molar ratio of precursor 1 to Cu-complex (1:3, 1:4. 2:3, 1:8). Compounds 3 and 4 were synthesized as references for identification of the side-products in the final radiotracer formulation. Various stationary phases (pentafluorophenyl, cyano, phenyl, C18) and mobile phases were tested to separate unwanted side products 3 and 4 by HPLC. Solid phase extraction (SPE) was performed with the C18 plus cartridge before the semi-preparative HPLC purification of [18F]2.

Ergebnisse: [18F]2 was achieved with a high radiochemical conversion of 85 % using 2 mg of 1, 10 mg of [Cu(OTf)2(py)4] (molar ratio of 1:4) in n-BuOH/DMI (1:2, v/v) at 110 °C for 5 min. SPE under acidic conditions (pH 2) resulted in around 90 % recovery of [18F]2 compared to only 20 % under neutral conditions. Due to hydrolysis of residual precursor 1 with TFA prior to semi-preparative HPLC purification, the content of 5 in the formulated final product could be reduced from 25 % (without TFA hydrolysis) to 0.5-1 %. The side-products 3 and 4 were successfully separated using a ReproSil C18AQ column (250 x 20 mm) and 48 % THF/ACN (1:1, v/v) buffered with 20 mM ammonium acetate. Compound [18F]2 was isolated with a radiochemical purity of >95 % and molar activities in the range of 60 GBq/µmol were achieved.

Schlussfolgerungen: Despite a number of hurdles, the CMRF reactions are currently being widely employed for the production of radiopharmaceuticals embodying non-activated 18F-aryl scaffolds. To overcome the occasional purification difficulties of the resulting radioligands, further improvements and mechanistic studies need to be undertaken.

Referenzen:

[1] Preshlock, S., et al. Chemical Reviews 2016, 116(2), 719-766.

  • Lecture (Conference)
    29. Jahrestagung der Arbeitsgemeinschaft Radiochemie / Radiopharmazie, 28.-30.09.2023, Bad Salzuflen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37724
Publ.-Id: 37724


New high-resolution microscopy approaches for understanding biocompatibility of hip implants

Podlipec, R.; Štrancar, J.; Barlič, A.; Dolinar, D.; Jenko, M.

Ensuring the biocompatibility of hip implants is essential for the safety, effectiveness, and longevity of these medical devices [1]. The material-induced tissue inflammation and immune reaction must be negligible while promoting tissue integration. However, the major unresolved issue in joint replacement is the occurrence of adverse biological reactions to wear debris, leading to severe inflammation [2] which has been observed at the subcellular level [3]. To gain a deeper understanding of the biocompatibility related to material chemistry and surface topography and to better predict the material functionality and clinical use, it is crucial to investigate the properties of cell adhesion, proliferation, and migration on the implant's surface. In this study, we demonstrate how Al2O3-coated titanium alloys with varying surface topographies and roughness affect the growth and morphology of human bone marrow mesenchymal stromal cells (BM-MSCs). This subcellular-level investigation was conducted on live cells using novel high-resolution 3D confocal fluorescence and backscatter microscopy.

1. Hu CY, Yoon TR. Biomaterials Research, 2018, 22, 33.
2. Cobelli N, Scharf B, Crisi GM, Hardin J, Santambrogio L. Nat Rev Rheumatol. 2011, 7, 600–608.
3. Podlipec R, Punzón-Quijorna E, Pirker L, Kelemen M, Vavpetič P, Kavalar R, Hlawacek G, Štrancar J, Pelicon P, Fokter SK, Materials, 2021, 14, 3048.

Related publications

  • Invited lecture (Conferences)
    5th International Symposium on Biomaterials (5ISB), 13.10.2023, Portorož, Slovenia

Permalink: https://www.hzdr.de/publications/Publ-37723
Publ.-Id: 37723


Supporting Data: Particulate matter triggers the formation of extracellular amyloid β and tau -containing plaques and neurite shortening in vitro

Sebastijanovič, A.; Podlipec, R.; Gianoncelli, A.; Hlawacek, G.; Bonanni, V.; Camassa, L. M. A.; Malmborg, V.; Kralj, S.; Pagels, J.; Vogel, U.; Zienolddiny-Narui, S.; Urbančič, I.; Koklič, T.; Štrancar, J.

Supplementary material including sample preparation, microscope setup, correlative microscopy analysis and supporting images.

Keywords: neurite shortening; neuronal degeneration; amyloid beta (Aβ); microtubule-associated protein (tau); air pollution; particulate matter; TiO2 nanotubes; diesel exhaust; CeO2 nanoparticles; iron oxide

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Permalink: https://www.hzdr.de/publications/Publ-37722
Publ.-Id: 37722


Understanding electronic correlations in warm dense quantum plasmas

Dornheim, T.

Warm dense matter (WDM)---an extreme state that is characterized by extreme densities and
temperatures---has emerged as one of the most active frontiers in plasma physics and material
science. In nature, WDM occurs in astrophysical objects such as giant planet interiors and brown
dwarfs. In addition, WDM is highly important for cutting-edge technological applications such as
inertial confinement fusion and the discovery of novel materials. In the laboratory, WDM is studied
experimentally in large facilities around the globe, and new techniques have facilitated
unprecedented insights. Yet, the interpretation of these experiments requires a reliable diagnostics
based on accurate theoretical modeling, which is a notoriously difficult task [1].
In this work, I will give an overview of how we can use exact ab-initio path integral Monte Carlo
(PIMC) simulations [2] together with thermal density functional theory (DFT) calculations to get
new insights into the behavior of WDM. Moreover, I will show how switching to the imaginary-
time representation allows us to significantly improve the interpretation of X-ray Thomson
scattering (XRTS) experiments, which are a key diagnostic for WDM [3]. Specifically, I will
present a model-free temperature diagnostic [4] based on the well-known principle of detailed
balance, but available for all wave numbers, and a new idea to directly extract the electron—
electron static structure factor from an XRTS measurement [5]. As an outlook, I will show how new
PIMC capabilities will allow to give us novel insights into electronic correlations in warm dense
quantum plasmas, leading to unprecedented agreement between experiments [6] and theory.
[1] M. Bonitz et al., Physics of Plasmas 27, 042710 (2020)
[2] M. Böhme et al., Physical Review Letters 129, 066402 (2022)
[3] S. Glenzer and R. Redmer, Reviews of Modern Physics 81, 1625 (2009)
[4] T. Dornheim et al., Nature Communications 13, 7911 (2022)
[5] T. Dornheim et al., arXiv:2305.15305 (submitted)
[6] T. Döppner et al., Nature 618, 270-275 (2023)

  • Lecture (others)
    CFEL Theorie Seminar, 25.10.2023, Hamburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37721
Publ.-Id: 37721


Design of a primary heat exchanger in a sCO2 power cycle for energy storage systems

Guille-Bourdas, A. F.; Unger, S.; Hampel, U.

Renewable energy sources are the key for long-term decarbonisation of the energy system. However, the intermittent nature of renewables, such as solar energy or wind energy, does not always meet the energy demand in the electrical grid. Considering the fact that both electricity production and consumption vary independently, balancing the grid is a major challenge for the development of an energy system based on renewable energies. Within this framework, Thermal Energy Storage systems (TES) coupled with a power cycle have gained popularity since they can store energy from renewable sources during the periods of high production and release it when necessary.
To convert thermal energy into electricity, a power cycle is required. Given the relative high temperature range (600 - 1000 °C), supercritical CO2 (sCO2) is the most promising material as working fluid for the power cycle, from efficiency and safety considerations. Thus, the Primary Heat Exchanger (PHX) must be carefully designed as the fluid pressures in the TES and the power cycle are namely 1 - 10 bar and 200 - 250 bar.
The present work consists of two parts, one elaborates a 1D model in order to design the PCHE regarding a certain set of boundary conditions. The model requires heat transfer and pressure loss correlations from the literature to estimate the Nusselt number and friction factor, which strongly depends on the geometry. It was found that the zigzag channel design intensifies both heat transfer and pressure drop phenomena, which is not suitable for the hot fluid from an economic prospective. Furthermore, 3D simulations by Computational Fluid Dynamics (CFD) were done and compared to the results from the 1D model to ensure the validity of the correlations. It was also found that the results match those from the literature, thus validating the 1D model.

Keywords: Heat exchanger; Printed circuit heat exchanger; Supercritical CO2; Computational fluid dynamics; 1D model; Brayton power cycle

  • Poster
    Doctoral seminar, 17.-19.10.2023, Schöneck, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37720
Publ.-Id: 37720


Data from a case study of the application of Gas Flow Modulation technique for measuring the axial gas dispersion coefficient in bubble columns

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

The data were used to exemplify the application of Gas Flow Modulation (GFM) for measuring the axial gas dispersion coefficient in bubble column reactors operated at ambient conditions. For more details, please refer to the atteched PDF.

Keywords: Gas flow modulation; Bubble column; Axial gas dispersion coefficient; case-study

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Permalink: https://www.hzdr.de/publications/Publ-37719
Publ.-Id: 37719


High-temperature solid thermal energy storage for Power-Heat-Power systems

Bangalore Mohankumar, M.

Presentation for PhD seminar

  • Contribution to proceedings
    Annunal PhD. Seminar, 17.-19.10.2023, Schöneck/Vogtland, Germany
    High-temperature solid thermal energy storage for Power-Heat-Power systems

Permalink: https://www.hzdr.de/publications/Publ-37714
Publ.-Id: 37714


Synthese und Charakterisierung von Bispidinen als bifunktionelle Liganden für die spezifische Bindung von PSMA und der Radiomarkierung mit Quecksilber-197(m)

Ullrich, N.

Für die Untersuchung des Radionuklidpaares 197(m)Hg in der Theranostik, ist die Entwicklung eines Radiopharmakons erforderlich, bei dem unter In-vivo-Bedingungen keine Dissoziation und somit keine Freisetzung von zytotoxischem Quecksilber stattfindet. Das potenzielle metallorganische Radiopharmakon soll dabei auf einem in vivo stabilen Bispidin-Grundgerüst basieren. Dieses bietet die Möglichkeit das Radionuklid durch einfache Substitution über eine benzylische Struktureinheit kovalent an das Grundgerüst zu binden. Durch die dreidimensionale Struktur erfährt das Radionuklid dabei eine sterische Abschirmung. Zusätzlich fungiert das Grundgerüst als bifunktioneller Ligand, der durch eine weitere Substitution in der C9-Position das PSMA-Bindungsmotiv binden kann.
Auf Grundlage der bisherigen Forschungsergebnisse soll das potenzielle Radiopharmakon auf einem Bispidin-Grundgerüst basieren. Hierfür müssen die pharmakologischen Eigenschaften wie die Lipophilie angepasst werden, was durch die Verwendung von Methylgruppen in den Positionen C1 und C5 erreicht werden soll. Weiterhin soll durch die gezielte Funktionalisierung der C9-Position des Bispidin-Grundgerüsts eine Bindung des PSMA-Bindungsmotivs an das Grundgerüst ermöglicht werden, wofür verschiedene Ansätze untersucht werden sollen. Das vorrangige Ziel besteht dabei in der Einführung und Funktionalisierung eines primären Amins und deren Substitution, um die Bindung des Vektormoleküls zu erreichen.
Nach Entfernung des C1-Bausteines aus dem Aminal soll durch nukleophile Substitution jeweils eine Trialkylstannyl-funktionalisierte Struktureinheit an den sekundären Aminen gebunden werden, um eine Fluchtgruppe für die folgende, kovalente Bindung des Quecksilbers zu ermöglichen. Hierfür soll einem vorangehenden Schritt das Trialkylstannyl-funktionalisierte Molekül synthetisiert werden. Basierend auf der Arbeit von I. M. GIPLIN und Kollegen soll statt der Trimethylstannyl- eine Triethylstannyl-Verbindung genutzt werden, um die beobachtete Instabilität zu umgehen.
Nachfolgend soll das PSMA-Bindungsmotiv über eine Peptidbindung an die funktionalisierte C9-Position des Grundgerüsts gebunden werden, wodurch sich das Radiopharmakon später selektiv an maligne Zellen anlagern kann. Darüber hinaus soll die anschließende Radiomarkierung mit dem Nuklidpaar 197(m)Hg ermöglicht werden.

Keywords: Quecksilber-197(m); Bispidine; theranostisches Konzept

  • Master thesis
    TU Dresden - Fakultät Chemie und Lebensmittelchemie, 2023
    Mentor: PD Dr. Constantin Mamat
    114 Seiten

Permalink: https://www.hzdr.de/publications/Publ-37712
Publ.-Id: 37712


Exchange gap in GdPtBi probed by magneto-optics

Polatkan, S.; Uykur, E.; Mohelsky, I.; Wyzula, J.; Orlita, M.; Shekhar, C.; Felser, C.; Dressel, M.; Pronin, A. V.

We measured the magneto-reflectivity spectra (4 – 90 meV, 0 – 16 T) of the triple-point semimetal GdPtBi and found them to demonstrate two unusual broad features emerging in field. The electronic bands of GdPtBi are expected to experience large exchange-mediated shifts, which lends itself to a description via effective Zeeman splittings with a large g-factor. Based on this approach, along with an ab-initio band structure analysis, we propose a model Hamiltonian that describes our observations well and allows us to estimate the effective g-factor, g∗ = 95. We conclude that we directly observe the exchange-induced Γ8 band inversion in GdPtBi by the means of infrared spectroscopy.

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Permalink: https://www.hzdr.de/publications/Publ-37711
Publ.-Id: 37711


Viscosity influence on human hepatoma tumor spheroids formation in core-shell alginate-carboxymethylcellulose microcapsules

Peng, X.; Janićijević, Ž.; Lemm, S.; Laube, M.; Pietzsch, J.; Bachmann, M.; Baraban, L.

Biomolecular and physical stimuli, such as stiffness and stress, of the extracellular environment, regulate collective cell dynamics and tissue patterning. The viscosity in the tumor microenvironment can increase due to the accumulation of macromolecules over time. Islands of rigid tumors are surrounded by soft cells that are more deformable than their healthy counterparts. Nonetheless, how the viscosities of the tumor microenvironment regulate collective cell spatial and temporal organization is not fully understood. Here, we used the human hepatoma (HepG2) cancer cells, the basic structural component of the liver, as an example to study the influence of viscosity (range from 0.8 cP to 15 cP) on cancer cell collective behavior in 3D microcapsules reactors. Alginate/Alginate-carboxymethylcellulose microcapsules (AL/AL-CMC MCs) with HepG2 cells were generated using a home-made high-throughput droplet-based microfluidic platform. Cell distribution, cell proliferation, spheroids growth, morphology change, and cytoskeleton difference were observed and quantified, showing a significant effect on viscosity change. Importantly, F-actin and keratin 8 intensity and distribution results can be a cue that viscosity increases enhancing the ability of cancer cells to squeeze through dense tissue. The results thus demonstrate that extracellular viscosity as an important physical cue regulates tumor development relevance to cancer biology.

Keywords: physical stimuli; viscosity; HepG2; gel matrix

  • Lecture (Conference)
    International Conference on Nanotechnologies & Bionanoscience, 14.09.2023, Heraklion, Greece

Permalink: https://www.hzdr.de/publications/Publ-37708
Publ.-Id: 37708


Application of focused ion beams for quantum and information technologies

Astakhov, G.

In the first part, we present our recent result on mask-free nanofabrication involving a quasi-deterministic creation of single G- and W-centers in silicon wafers using focused-ion beam (FIB) writing. Using these centers, we implement a scalable, broad-beam implantation protocol compatible with the complementary-metal-oxide-semiconductor (CMOS) technology to fabricate telecom single photon emitters at desired positions on the nanoscale In the second part, we present a concept of ultralong, high-density data archiving based on optically active atomic-size defects in silicon carbide (SiC). The information is written in these defects by FIB and read using photoluminescence (PL) or cathodoluminescence (CL). With near-infrared laser excitation, grayscale encoding and multi-layer data storage, the areal density corresponds to that of Blu-ray discs.

Keywords: Quantum technology; Defects; Focused ion beam

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  • Invited lecture (Conferences) (Online presentation)
    Sino-German Symposium Defect Engineering in SiC and Other Wide Bandgap Semiconductor, 23.-24.10.2023, Conference Center, SUSTech, Shenzhen, Guangdong, China

Permalink: https://www.hzdr.de/publications/Publ-37705
Publ.-Id: 37705


Learning to reconstruct the bubble distribution with conductivity maps using Invertible Neural Networks and Error Diffusion

Kumar, N.; Krause, L.; Wondrak, T.; Eckert, S.; Eckert, K.; Gumhold, S.

Electrolysis is crucial for eco-friendly hydrogen production, but gas bubbles generated during the process hinder reactions, reduce cell efficiency, and increase energy consumption. Additionally, these gas bubbles cause changes in the conductivity inside the cell, resulting in corresponding variations in the induced magnetic field around the cell. Therefore, measuring these gas bubble-induced magnetic field fluctuations using external magnetic sensors and solving the inverse problem of Biot-Savart’s Law allows for estimating the conductivity in the cell and, thus, bubble size and location. However, determining high-resolution conductivity maps from only a few induced magnetic field measurements is an ill-posed inverse problem. To overcome this, we exploit Invertible Neural Networks (INNs) to reconstruct the conductivity field. Our qualitative results and quantitative evaluation using random error diffusion show that INN achieves far superior performance compared to Tikhonov regularization.

Keywords: Machine Learning; Invertible Neural Networks; Water Electrolysis; Biot-Savart Law

  • Open Access Logo Lecture (Conference)
    11th World Congress on Industrial Process Tomography, 06.-08.09.2023, Mexiko-Stadt, Mexiko
  • Open Access Logo Contribution to proceedings
    11th World Congress on Industrial Process Tomography, 06.-08.09.2023, Mexiko-Stadt, Mexiko

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Permalink: https://www.hzdr.de/publications/Publ-37702
Publ.-Id: 37702


Current Tomography - Localization of void fractions in conducting liquids by measuring the induced magnetic flux density

Krause, L.; Kumar, N.; Wondrak, T.; Gumhold, S.; Eckert, S.; Eckert, K.

A novel concept of a measurement technology for the localization and determination of the size of gas bubbles is presented, which is intended to contribute to a further understanding of the dynamics of efficiency-reducing gas bubbles in electrolyzers. A simplified proof-of-concept (POC) model is used to numerically simulate the electric current flow through materials with significant differences in electrical conductivity. Through an automated approach, an extensive data set of electric current density and conductivity distributions is generated, complemented with determined magnetic flux densities in the surroundings of the POC cell at virtual sensor positions. The generated data set serves as testing data for various reconstruction approaches. Based on the measurable magnetic flux density, solving Biot-Savart’s law inversely is demonstrated and discussed with a model-based solution of an optimization problem, of which the gas bubble locations are derived.

Keywords: current tomography; magnetic field measurement; current density distribution; inverse problem

  • Open Access Logo Lecture (Conference)
    11th World Congress on Industrial Process Tomography, 06.-08.09.2023, Mexiko-Stadt, Mexiko
  • Open Access Logo Contribution to proceedings
    11th World Congress on Industrial Process Tomography, 06.-08.09.2023, Mexiko-Stadt, Mexiko

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Permalink: https://www.hzdr.de/publications/Publ-37701
Publ.-Id: 37701


Example Dataset from a Laser Ion Beam Accelearation Experiment for the Lecture on Research Software Engineering

Metzkes-Ng, J.; Zeil, K.; Bernert, C.; Reimold, M.; Gaus, L.; Assenbaum, S.; Schlenvoigt, H.-P.
DataCurator: Knodel, Oliver; ContactPerson: Juckeland, Guido

The dataset is an example experiment with images and metadata from the Laser-driven Ion Acceleration at HZDR from 2019-08-29. The dataset is used for the lecture on research Software Engineering (RSE) at Technische Universität Dresden.

Keywords: Laser Ion Beam Accelearation; Data Management; Metadata; Research Software Engineering

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Permalink: https://www.hzdr.de/publications/Publ-37699
Publ.-Id: 37699


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

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

Understanding the composition of Earth's core and mantle is a major challenge in geoscience
and materials science. The core is primarily made of iron, but its density is known to be
slightly lower than pure iron. Hydrogen contributes to this density deficit, leading to
significant interest in the properties and structure of iron hydrides under high pressure.

Previous studies have shown that the dhcp phase of FeH remains stable at lower pressures (10-40 GPa)
but undergoes phase transitions to hcp and fcc phases at higher pressures.
This study focuses on a theoretical exploration of the potential energy surfaces (PESs) of FeH under
varying pressure conditions. The objective is to demonstrate the effectiveness of automated and systematic
methods for training and validating transferable machine-learned interatomic potential (ML-IAP) using global
optimization techniques. By utilizing this potential, which significantly reduce computational costs,
the phase diagram of the stoichiometric Fe-H system is analyzed across a range of pressures.

To achieve this, we utilize the PyFLAME code to construct a highly transferable ML-IAP.
With this accurate potential, the PESs of bulk FeH structures are systematically investigated
through global sampling using the minima hopping method. This comprehensive exploration enables the prediction
of stable and metastable iron hydrides from 0 to 100 GPa. Density functional theory calculations are conducted
to refine the predicted structures and evaluate their dynamical stability.
The findings of this study reveal a wide range of novel low-energy polymorphs of FeH at each
pressure level, alongside the recovery of well-known structures in the literature.

  • Open Access Logo Poster
    NHR Conference 2023, 18.-19.09.2023, Berlin, Germany

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Permalink: https://www.hzdr.de/publications/Publ-37698
Publ.-Id: 37698


Orientational mercury removal from aqueous solution using three-dimensionally structured CuxS nanocluster anchored attapulgite

Dai, G.; Huang, J.; Ding, W.; Qiu, L.; Zhang, W.; Gu, Q.; Wang, Z.; Hu, Z.; Quan, C.; Li, P.

Toxic mercury-containing wastewater emitted from mining and nonferrous metallurgy seriously threatens human health and aquatic ecosystem. Effective mercury removal interfered with other coexisting metal ions in wastewater poses major challenges, requiring simple and sustainable methods. In this work, a novel three-dimensional (3D) CuxS nanocluster-anchored attapulgite (ATP@CuxS) is tailored for orientational mercury adsorption from diluted mercury-containing wastewater. The prepared ATP@CuxS adsorbent exhibited an unparalleled Hg2+ adsorption capacity of 746.48 mg g-1 among ever-reported clay-based adsorbents. Mercury-containing wastewater with an initial concentration of 5 mg L-1, and solution pH of 6.5 was ~100% removed within 20 min, and no interference by coexisting anionic and cation ions was observed. In the determination of the adsorption mechanism, in-situ intercalation and vulcanization of Cu2+ on ATP base constructs nanoclusters shaped CuxS that provide abundant active sites for Hg2+ adsorption. The negatively charged ATP facilitates positive Cu2+ immobilization on its surface followed by inorganic sulfide generation. This interfacial electrical compatibility makes a compact and stable composite.
33 Hydrophilic ATP modulated the uniform dispersion performance of ATP@CuxS, and
34 the dense CuxS package contributed to easier sedimentation and recovery after Hg2+
35 adsorption in water. Furthermore, Hg2+ removal efficiency was maintained at 70% after
36 8 times repetitions, indicating a gentle feasibility as a mass-generated adsorbent. The
37 proposed interface engineering from the perspective of micro-interface electrical
38 compatibility creates an attractive and easily accessible system that combines efficiency,
39 capacity, selectivity, and reusability for orientational removing Hg2+ from wastewater.

Keywords: CuxS nanocluster; Attapulgite; Interface engineering; Mercury removal; Orientational removal; Feasibility evaluation

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  • Secondary publication expected from 26.01.2025

Permalink: https://www.hzdr.de/publications/Publ-37697
Publ.-Id: 37697


Nucleation of surface nanobubbles in electrochemistry: Analysis with nucleation theorem

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

The formation of single bubbles at nanoelectrodes during electrochemical reactions allows to accurately identify the critical nucleus for bubble formation. As demonstrated before, combining nanoelectrode experiments and an analysis approach based on classical nucleation theory (CNT) delivers useful insight into bubble nucleation. In this work we propose an alternative approach to analyze the critical nuclei by applying the nucleation theorem (NT), which is able to overcome the inherent shortcomings of CNT. The size of the critical nucleus can be calculated more accurately by fitting experimental data in a simple form of the NT. Simulating the local gas concentration using a finite element approach, and considering the effect of gas oversaturation on the interfacial tension and the real gas compressibility, we obtain a more realistic estimation of the critical nuclei morphology. With the NT-based analysis presented, we re-analyze the nucleation data reported before. The properties of the critical nuclei obtained here are roughly consistent with those obtained from the CNT-based approach. In addition, we confirm that the critical nucleus for bubble formation in high gas oversaturation is featured with a contact angle much larger than Young’s contact angle.

Keywords: nanobubble; critical nucleous; nucleation theorem; finite element simulation; contact angle

Permalink: https://www.hzdr.de/publications/Publ-37696
Publ.-Id: 37696


Defect evolution in GaN thin film heterogeneously integrated with CMOS-compatible Si(100) substrate by ion-cutting technology

Shi, H.; Yi, A.; Ding, J.; Liu, X.; Qin, Q.; Yi, J.; Hu, J.; Wang, M.; Cai, D.; Wang, J.; Xu, K.; Mu, F.; Suga, T.; Heller, R.; Wang, M.; Zhou, S.; Xu, W.; Huang, K.; You, T.; Ou, X.

Ion-cutting technology is an ingenious solution to the high-quality heterogeneous integration of GaN thin films with CMOS-compatible Si(100) substrate, which provides a platform to combine GaN-based optoelectronics, high-frequency and high-power electronics with digital signal processing, logic computation, and control of Si(100) CMOS. Previously, we reported the fabrication of 2-inch GaN film on SiO2/Si(100) substrate (GaNOI) by the ion-cutting technology. In this study, we further study the defect evolution in the transferred GaN films, which is needed to promote the practical applications of the GaNOI material platform.

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Permalink: https://www.hzdr.de/publications/Publ-37695
Publ.-Id: 37695


The Heterogeneity of the Sandy Facies of Opalinus Clay across Scales, from Seismic Surveys to Radionuclide Diffusion - an in-situ Test in the Swiss Rock Laboratory Mont Terri

Heberling, F.; Albers, H.; Beilecke, T.; Deissmann, G.; Fischer, C.; Furche, M.; Geckeis, H.; Hoyer, E.-M.; Joseph, C.; Liebscher, A.; van Loon, L.; Lüth, S.; Ma, B.; Metz, V.; Müller, K.; Nowak, U.; Quinto, F.; Rebscher, D.; Rühaak, W.; Schulte, F.; Steegborn, F.; Tietz, T.

Many countries consider clay rock formations as potential host rocks for high-level nuclear waste disposal. Clay rocks may exhibit heterogeneity on various scales, from the micro- to the facies-scale. In the Mont Terri rock laboratory, Switzerland, various experiments study properties and characteristics of the Jurassic Opalinus Clay, which is the target host rock for the Swiss nuclear waste repository but may also provide proxies for other considered clay rock formations. At Mont Terri, the Opalinus Clay mainly appears in a shaly and two sandy facies. So far, diffusion experiments at Mont Terri focussed on the relatively homogeneous shaly facies. The upper sandy facies (SF-OPA) exhibits a more pronounced internal – mineralogical and textural – heterogeneity. Clay rocks with comparable heterogeneity to SF-OPA may be present among the lower Cretaceous clay rocks of northern Germany, which are among the potential host rock candidates for a future German nuclear waste repository. Since 2020, seven institutions develop an in-situ diffusion experiment in SF-OPA, the so-called DR-D experiment, to explore the impact of rock heterogeneity on radionuclide diffusion in low permeability clay rocks.
So far, the DR-D experiment combined high-resolution seismic tomography, borehole logging, and detailed drill core analyses to characterize the heterogeneity of the selected SF-OPA area. The targeted rock zone exhibits a layer starting ca. 10 m below the gallery surface, which is characterized by relatively high seismic velocities. This layer is as well evident in the natural gamma- and the neutron backscattering logs. In the drill cores it stands out as whitish rock characterized by large concretions and traces of bioturbation in contrast to the dark layered clay-rock above and below with smaller concretions. Detailed analysis of seismic signals and drill-cores is still ongoing. In future, an in-situ diffusion test using various radioactive and non-radioactive tracers (e.g., HTO, 129I, 22Na) will be conducted targeting the evidently heterogeneous rock section 10 m below the gallery surface. The evolution of tracer concentrations in a synthetic porewater circulating in the diffusion interval will be monitored. A second seismic tomography survey is planned after the termination of the diffusion experiment. Finally, overcoring and post-mortem analysis of the rock affected by tracer diffusion will be used to determine the local variability of diffusion parameters.
In this contribution, we present the general concept, technical layout, and expected scientific impact of the DR-D experiment, as well as first results from field and related laboratory studies.

  • Contribution to proceedings
    18th international conference on the chemistry and migration behaviour of actinides and fission products in the geosphere, 24.-29.09.2023, Nantes, France
  • Poster
    18th international conference on the chemistry and migration behaviour of actinides and fission products in the geosphere, 24.-29.09.2023, Nantes, France, 24.-29.09.2023, Nantes, France

Permalink: https://www.hzdr.de/publications/Publ-37694
Publ.-Id: 37694


Data publication: Chelator Impact: Investigating the Pharmacokinetic Behavior of Copper-64 Labeled PD-L1 Radioligands

Krutzek, F.; Donat, C.; Stadlbauer, S.

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

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Permalink: https://www.hzdr.de/publications/Publ-37693
Publ.-Id: 37693


Poly(benzimidazobenzophenanthroline)-Ladder-Type Two-Dimensional Conjugated Covalent Organic Framework for Fast Proton Storage

Wang, M.; Wang, G.; Naisa, C.; Fu, Y.; Manoj Gali, S.; Paasch, S.; Wang, M.; Wittkaemper, H.; Papp, C.; Brunner, E.; Zhou, S.; Beljonne, D.; Steinrück, H.-P.; Dong, R.; Feng, X.

Electrochemical proton storage plays an essential role in designing next-generation high-rate energy storage devices, e.g., aqueous batteries. Two-dimensional conjugated covalent organic frameworks (2D c-COFs) are promising electrode materials, but their competitive proton and metal-ion insertion mechanisms remain elusive, and proton storage in COFs is rarely explored. Here, we report a perinone-based poly(benzimidazobenzophenanthroline) (BBL)-ladder-type 2D c-COF for fast proton storage in both a mild aqueous Zn-ion electrolyte and strong acid. We unveil that the discharged C−O− groups exhibit largely reduced basicity due to the considerable π-delocalization in perinone, thus affording the 2D c-COF a unique affinity for protons with fast kinetics. As a consequence, the 2D c-COF electrode presents an outstanding rate capability of up to 200 A g−1 (over 2500 C), surpassing the state-of-the-art conjugated polymers, COFs, and metal–organic frameworks. Our work reports the first example of pure proton storage among COFs and highlights the great potential of BBL-ladder-type 2D conjugated polymers in future energy devices.

Permalink: https://www.hzdr.de/publications/Publ-37692
Publ.-Id: 37692


Preclinical evaluation of an ¹⁸F-labeled Nε-acryloyllysine piperazide for covalent targeting of transglutaminase 2

Wodtke, R.; Laube, M.; Hauser, S.; Meister, S.; Ludwig, F.-A.; Fischer, S.; Kopka, K.; Pietzsch, J.; Löser, R.

Background: Transglutaminase 2 (TGase 2) is a multifunctional protein and has a prominent role in various physiological and pathophysiological processes. In particular, its transamidase activity, which is rather latent under physiological conditions, gains importance in malignant cells and supports tumor development and progression. Thus, there is a great need of theranostic probes for targeting tumor-associated TGase 2, and targeted covalent inhibitors appear particularly attractive as vector molecules in this regard. Such an inhibitor, equipped with a radionuclide suitable for noninvasive imaging, would be supportive for answering the general question on the possibility for functional characterization of tumor-associated TGase 2 in vivo. For this purpose, the recently developed ¹⁸F-labeled Nε-acryloyllysine piperazide [¹⁸F]7b, which is a potent and selective irreversible inhibitor of TGase 2, was subject to a detailed radiopharmacological characterization herein, including ex vivo biodistribution, metabolism and tumor uptake.
Results: An alternative radiosynthesis of [¹⁸F]7b under basic conditions is presented, which demands less than 300 µg of the respective trimethylammonio precursor per synthesis and provides [¹⁸F]7b in good radiochemical yields (17±7%) and high (radio)chemical purities (≥99%). Ex vivo biodistribution in healthy mice at 5 and 60 min p.i. revealed no permanent enrichment of ¹⁸F-activity in tissues with the exception of the bone tissue. In vivo pretreatment with ketoconazole and in vitro murine liver microsome (MLM) studies complemented by UPLC-MS/MS analysis demonstrated that bone uptake originates from metabolically released [¹⁸F]fluoride. Further metabolic transformations of [¹⁸F]7b include mono-hydroxylation and glucuronidation. Based on blood sampling data and MLM experiments, pharmacokinetic parameters such as plasma and intrinsic clearance were derived, which substantiated the apparently rapid distribution of [¹⁸F]7b in and elimination from the organisms. A TGase 2-mediated uptake of [¹⁸F]7b in different tumor cell lines could not be proven. Moreover, evaluation of [¹⁸F]7b in melanoma tumor xenograft models based on A375-hS100A4 (TGase 2 +) and MeWo (TGase 2 -) cells by ex vivo biodistribution and PET imaging were not indicative for a TGase 2-specific targeting.
Conclusion:
[¹⁸F]7b is a valuable radiometric tool to study TGase 2 in vitro under various conditions. However, its suitability for targeting tumor-associated TGase 2 is strongly limited due its unfavorable pharmacokinetic properties including a pronounced metabolization. Consequently, from a radiochemical perspective [18F]7b requires structural modifications to overcome these limitations.

Keywords: radiofluorination; liver microsomes; biodistribution; PET imaging; plasma clearance; pharmacokinetics; radiometabolites; defluorination

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37691
Publ.-Id: 37691


Uranium(VI) interactions with Pseudomonas sp. PS-0-L, V4-5-SB and T5-6-I

Kasko, J.; Li, X.; Müller, K.; Ge, Y.; Vettese, G. F.; Law, G. T. W.; Siitari-Kauppi, M.; Huittinen, N. M.; Raff, J.; Bomberg, M.; Herzig, M.

Pseudomonas sp. are indigenous inhabitants of ombrotrophic bogs which can survive in acidic, nutrient-poor environments with wide temperature fluctuations. Their interactions with contaminant radionuclides can influence radionuclide biogeochemistry in boreal environment. Here, uranium (U(VI)) bioassociation by Pseudomonas sp. PS-0-L, V4-5-SB and T5-6-I isolated from a boreal bog was studied by a combination of batch contact experiments, spectroscopy and microscopy. All strains removed U from the solution and the U bioassociation efficiency was affected by the nutrient source, incubation temperature, time and pH. Highest U bioassociation occurred in the strains PS-0-L (0.199 mg U/gBDW) and V4-5-SB (0.223 mg U/gBDW). Based on in-situ attenuated total reflection Fourier transformation infrared spectroscopy (ATR FT-IR) analyses, the most likely functional groups responsible for U binding were the cell surface carboxyl groups. In addition, transmission electron microscopy with energy dispersive X-ray spectroscopy (TEM/EDX) showed dense intra-cellular round- and needle-like U accumulations in the cytoplasm and near to the inner cell membrane. The presence of U with phosphorus was indicated in elemental mapping. Modelled data showed ≡SOOHx-1 and ≡SOCO2Hx-1 as the dominant surface sites, contributing to the negative cell surface charge. The U removal efficiency depended on the U(VI) speciation under different pH conditions. At pH 5, the main species reacting with bacterial cell surfaces was UO22+, while at pH 9 UO2(OH)2 and UO2(OH)3- dominated the reactions. Further, U bioassociation increased with increasing aqueous U(VI) concentrations. Our data suggests U bioassociation on 1) outer cell membrane/cell wall associated carboxyl groups (e.g., proteins), and 2) intracellular phosphate groups (e.g., phospholipids).

Keywords: bioassociation; biosorption; bioaccumulation; modelling; carboxyl group; phosphate group

Permalink: https://www.hzdr.de/publications/Publ-37690
Publ.-Id: 37690


Oppositely charged surfactants and nanoparticles at the air-water interface: Influence of surfactant to nanoparticle ratio

Eftekhari, M.; Schwarzenberger, K.; Karakashev, S. I.; Grozev, N. A.; Eckert, K.

Hypothesis: The interactions between oppositely charged nanoparticles and surfactants can significantly influence the interfacial properties of the system. Traditionally, in the study of such systems, the nanoparticle concentration is varied while the surfactant concentration is kept constant, or vice versa. However, we believe that a defined variation of both components' concentration is necessary to accurately assess their effects on the interfacial properties of the system. We argue that the effect of nanoparticle-surfactant complexes can only be properly evaluated by keeping the surfactant to nanoparticle ratio constant.

Experiments: Zeta potential, dynamic light scattering, high amplitude surface pressure and surface tension measurements are employed synergistically to characterize the interfacial properties of the nanoparticle-surfactant system. Interferometric experiments are performed to highlight the effect of surface concentration on the stability of thin liquid films.

Findings: The interfacial properties of surfactant/nanoparticle mixtures are primarily determined by the surfactant/nanoparticle ratio. Below a certain ratio, free surfactant molecules are removed from the solution by the formation of surfactant-nanoparticle complexes. Surprisingly, even though the concentration and hydrophobicity of these complexes do not seem to have a noticeable impact on the surface tension, they do significantly affect the rheological properties of the interface. Above this ratio, free surfactant monomers and nanoparticle-surfactant complexes coexist and can co-adsorb at the interface, changing both the interfacial tension and the interfacial rheology, and thus, for example, the foamability and foam stability of the system.

Keywords: Nanoparticle surfactant complexes; Surfactant to nanoparticle ratio; Surface pressure isotherm; Zeta potential; Film stability

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  • Secondary publication expected from 04.10.2024

Permalink: https://www.hzdr.de/publications/Publ-37689
Publ.-Id: 37689


Opportunities and challenges for spintronics

Adelmann, C.; Jenkins, A.; Pirro, P.; Schultheiß, K.; van Dijken, S.; Kruglyak, V.; Bortolotti, P.

Conventional electronics use the flow of electric charges and are based on standard semiconductors. Spintronic devices exploit the electrons’ spin to generate and control currents and to combine electric and magnetic signals. Today there is a strong effort worldwide to integrate spintronic devices with standard CMOS technology towards hybrid spin-CMOS chips, offering advantages in terms of power consumption, compactness, and speed. Recent results (from SAMSUNG [1], TSMC [2], etc.) confirm the merit of this approach.

Keywords: spintronics; magnonics

Permalink: https://www.hzdr.de/publications/Publ-37688
Publ.-Id: 37688


Research data management of laser-plasma science at HZDR

Schlenvoigt, H.-P.; Tippey, K. E.; Horn, W.; Bock, S.; Pape, D.; Knodel, O.; Kluge, T.; Irman, A.; Zeil, K.; Schramm, U.

The Draco laboratory at HZDR is a versatile, multi-arm and multi-target-area facility, consisting of several, independent subsystems. The lack of an overarching DAQ is balanced by interfaces of the subsystems and custom inter-linking agents. We present recent progress of implementing such software agents, connecting to the center’s electronic lab documentation system. First, manual logging of shot parameters and observations is lifted from spreadsheet software to a flexible web-app, writing to a database (DB). The laser-internal logging is exported to a DB and internal software triggering is forwarded to experiments. That provides a connection between laser-internal indexing and experiment-based indexing (another DB) and enables near-online data processing. The latter comprises file path logging and validation according to the shot’s acquisition settings for further analysis as well as basic on-shot analysis scripts, both enabling near-online visualization to better guide the course of experiments.
Likewise, parameters and results from simulations are logged to databases, enabling machine learning techniques and better computing resource management.
For a long-term, FAIR storage, the HELPMI project starts exploring the possibilities of openPMD and NeXus to ingest experimental data. That project shall serve as initiative for the global LPA community to find a data and metadata standard.

Keywords: data standard; metadata

  • Open Access Logo Poster
    6th European Advanced Accelerator Concepts workshop, 18.-22.09.2023, La Biodola Bay, Isola d'Elba, Italy

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Permalink: https://www.hzdr.de/publications/Publ-37687
Publ.-Id: 37687


Synthese und Radiomarkierung von macropa-PSMA-Derivaten für die Tumorbildgebung mit Iod-123

Krönke, T.

Ziel: macropa-PSMA-Konjugate mit Albuminbinder zur zielgerichteten Alphatherapie mit 225Ac wurde innerhalb der Arbeitsgruppe bereits erfolgreich synthetisiert und in vitro und in vivo untersucht.[1,2] Die dabei eingeführte albuminbindende Einheit bietet die Grundlage zur Erarbeitung eines theranostischen Ansatzes indem, neben der Komplexierung des Alphaemitters 225Ac, die Bindung von Iod-123 als leicht zugängliches SPECT-Nuklid im gleichen Molekül ermöglicht wird. Vorteilhaft sind die milden Markierungsbedingungen sowie eine passende Halbwertszeit des Iodisotopes (t1/2 =13,2 h), welche die Bildgebung länger zirkulierender Substanzen ermöglicht.
Methoden: Die Synthese der peptidomimetischen Ausgangsverbindungen erfolgte angelehnt an die Vorarbeiten durch mehrstufige Peptidkupplungen und die Anbringung des Chelators mittels Cu-katalysierter Click-Reaktion. Anstelle der 4-(p-Iodphenyl)buttersäure wurde der entsprechende Zinnprecursor eingeführt, um die Verbindung durch eine elektrophile, aromatische Substitution mit 123I markieren zu können.

Keywords: macropa; Radiohybridkonjugate; Actinium-225; Iod-123; Alphatherapie

  • Master thesis
    TU Dresden - Fakultät Chemie und Lebensmittelchemie, 2023
    Mentor: PD Dr. Constantin Mamat
    72 Seiten

Permalink: https://www.hzdr.de/publications/Publ-37686
Publ.-Id: 37686


Synthese und Radiomarkierung von macropa-PSMA-Derivaten für die Tumorbildgebung mit Iod-123

Krönke, T.; Reissig, F.; Pietzsch, H.-J.; Kopka, K.; Mamat, C.

Ziel: macropa-PSMA-Konjugate mit Albuminbinder zur zielgerichteten Alphatherapie mit Actinium-225 wurde innerhalb der Arbeitsgruppe bereits erfolgreich synthetisiert und in vitro und in vivo untersucht. Die dabei eingeführte albuminbindende Einheit bietet die Grundlage zur Erarbeitung eines theranostischen Ansatzes indem, neben der Komplexierung des Alphaemitters Actinium-225, die Bindung von Iod-123 als leicht zugängliches SPECT-Nuklid im gleichen Molekül ermöglicht wird. Vorteilhaft sind die milden Markierungsbedingungen sowie eine passende Halbwertszeit des Iodisotopes (t1/2 =13,2 h), welche die Bildgebung länger zirkulierender Substanzen ermöglicht.
Methoden: Die Synthese der peptidomimetischen Ausgangsverbindungen erfolgte angelehnt an die Vorarbeiten durch mehrstufige Peptidkupplungen und die Anbringung des Chelators mittels Cu-katalysierter Click-Reaktion. Anstelle der 4-(p-Iodphenyl)buttersäure wurde der entsprechende Zinnprecursor eingeführt, um die Verbindung durch eine elektrophile, aromatische Substitution mit Iod-123 markieren zu können.
Ergebnisse: Durch die erfolgreiche Entwicklung einer Methode zur Iodierung der synthetisierten Zinnprecursoren mit hohen radiochemischen Ausbeuten konnten schließlich die einfach bzw. doppelt PSMA-gebundenen Verbindungen [123I]I-mcp-M-alb-PSMA und [123I]I-mcp-D-alb-PSMA hergestellt werden. Nach der Iodierung der Verbindungen wurde in vitro der Einfluss des 139La-Komplexes als auch der des unkomplexierten Chelators an der PSMA-positiven Zelllinie LNCaP untersucht.
Schlussfolgerungen: Die Einführung von Iod-123 in die bereits untersuchten Derivate mit stabilem Iod-127 ergab keine Änderungen der biologischen Ergebnisse. Damit ergibt sich der neue Aspekt des theranostischen Nutzens als hybrides Radiopharmakon mit einer weiteren Markierungsstelle in der Peripherie des eigentlichen Liganden.

Keywords: Alphatherapie; Actinium-225; Iod-123; Macropa; Radiohybridkonjugate

  • Lecture (Conference)
    29. Jahrestagung der Arbeitsgemeinschaft Radiochemie/Radiopharmazie, 28.-30.09.2023, Bad Salzuflen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37685
Publ.-Id: 37685


Detectors of SPM cantilever deflection based on field emission phenomenon

Gacka, E.; Kwoka, K.; Sierakowski, A.; Janus, P.; Hlawacek, G.; Gotszalk, T.

The most common deflection detection methods for micro-electromechanical systems (MEMS), like microcantilevers used in scanning probe microscopy, include optical methods based on optical beam deflection systems, piezoresistive or capacitive methods. This issue is still being pursued in order to develop a method with the highest possible deflection sensitivity. For this reason, attention is focused on exploiting the field emission phenomenon – the tunnelling of electrons through a potential barrier that occurs when the applied threshold voltage between electrodes is exceeded.
This work presents a method for microcantilever deflection detection based on field emission phenomenon – fig. 1a. As a result of cantilever deflection, the distance between the emitter tips (electrodes) was changed, resulting in a variation of the threshold voltage and field emission current. Nanotip field emitters were integrated into the microcantilevers using a focused electron and ion beam induced deposition (FEBID/FIBID) (fig. 1b). This one-step process allowed for the simplification of their fabrication technology. The effect of distance between electrodes and emitter shape on the emission enhancement factor was analysed. Preliminary usability tests of the sensor have been performed.
Acknowledgements: This work was supported by the National Science Centre, Poland PRELUDIUM-21 grant [“Nanometrology of field emission phenomena from electron beam deposited nanowires operating as nano- and picodeflection sensors – FEmet”, grant number 2022/45/N/ST7/03049]; and a short term scientific mission funded by the COST Action CA19140 (http://www.fit4nano.eu/).

Keywords: HIM; FIB; SPM; FIBID

Related publications

  • Lecture (Conference)
    XII Workshop on Applications of Scanning Probe Microscopy – STM/AFM 2023, 29.11.-03.12.2023, Zakopane, Polen

Permalink: https://www.hzdr.de/publications/Publ-37683
Publ.-Id: 37683


The MultiMorph Model for industrial multiphase flows

Schlegel, F.

Introduction to the MultiMorph model developed at HZDR for numerical simulation of multiphase flows with morphology transition

  • Lecture (Conference)
    2023 HZDR Science Conference, 15.-16.11.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37679
Publ.-Id: 37679


From Multiphase Code Repository by HZDR for OpenFOAM Foundation Software towards a Helmholtz Energy Multiphase Platform?

Schlegel, F.

Open source software has become indispensable for science, in particular with respect to the FAIR principles it is a sufficient requirement. The full access to the source code and the transparency of the open source research software requires completely new concepts and business models between software providers and users, as well as the organisation of the community. This poses a challenge, but on the other side opens up space for new, creative solutions and a new perspectives. Within open source software there is an enormous potential for more effective research and collaboration, which so far has been used only rarely by research organisations.
A very successful open source software for engineering applications is the C++-library OpenFOAM, which is developed for solving non-linear partial differential equations. HZDR has set itself the goal to ensure sustainable software development for our research. The contribution will present the experiences and learnings of HZDR from working with open-source software, exemplary for OpenFOAM, and from an intensive commitment as an OpenFOAM community member and contributor to the OpenFOAM Foundation release. The developers of the HZDR Multiphase Addon for OpenFOAM rely intensively on the Helmholtz Cloud Services, which provide a unique opportunity to foster sustainable software developments and collaboration. Based on the successful development of the HZDR Multiphase Addon and the growing importance of Computational Fluid Dynamics for reactor safety research the Bundesministerium für Umwelt, Naturschutz, nukleare Sicherheit und Verbraucherschutz finances the OpenFOAM_RCS project, a continuously growing, collaborative platform for qualification of OpenFOAM for nuclear safety research. The OpenFOAM_RCS platform is based on the Helmholtz Cloud Services and coordinated by HZDR in close collaboration with OpenFOAM Foundation.
The idea of the presentation is to present our experiences and to stimulate discussions with the aim to develop the HZDR Multiphase Addon and the OpenFOAM_RCS project into a Helmholtz Energy Multiphase Platform.

  • Poster
    Helmholtz Energy Conference 2023, 12.-13.06.2023, Koblenz, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37678
Publ.-Id: 37678


Lecture 13: Multiphase Developments with OpenFOAM Foundation Software

Schlegel, F.

A introduction into the open-source CFD toolbox OpenFOAM and sustainable development using the Helmholtz Cloud services

  • Lecture (Conference)
    19th Multiphase Flow Conference and Short Course: Simulation, Experiment and Application, 19.-23.06.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37677
Publ.-Id: 37677


Lecture 10: A Morphology Adaptive Multifield Two-Fluid Model

Schlegel, F.

An introduction into the MultiMorph Model developed at HZDR for numerical simulation of multiphase flows with morphology transitions.

  • Lecture (Conference)
    19th Multiphase Flow Conference and Short Course: Simulation, Experiment and Application, 19.-23.06.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37676
Publ.-Id: 37676


A Performance Study of Local Outlier Detection Methods for Mineral Exploration with Geochemical Compositional Data

Puchhammer, P.; Kalubowila, C.; Braus, L.; Pospiech, S.; Sarala, P.; Filzmoser, P.

In exploration geochemistry, mineral deposits are typically characterised by local changes of the analysed chemical composition, where enrichment of the targeted elements is expected. Local changes can also be found with local outlier detection methods, which are multivariate methods for outlier identification that incorporate the spatial neighbourhood of the samples. It is essential that geochemical data are treated as compositional data, and the requirements for their treatment depend on the specific local outlier detection method. We demonstrate how prominent local outlier detection methods can be used for mineral exploration with geochemical data that vary in scale, in the sampling density, and in data quality. The methods are compared based on known mineralisations, and recommendations for their usefulness are provided.

Keywords: geochmistry; till; exploration; robust statistics; logratio transformation

Permalink: https://www.hzdr.de/publications/Publ-37675
Publ.-Id: 37675


Structural investigations of Au-Ni aerogels: morphology and element distribution

Kresse, J.; Georgi, M.; Hübner, R.; Eychmüller, A.

The physical properties of nanomaterials are determined by their structural features, making accurate structural control indispensable. This carries over to future applications. In the case of metal aerogels, highly porous networks of aggregated metal nanoparticles, such precise tuning is still largely pending. Although recent improvements in controlling synthesis parameters like electrolytes, reductants, or mechanical stirring, the focus has always been on one particular morphology at a time. Meanwhile, complex factors, such as morphology and element distributions, are studied rather sparsely. We demonstrate the capabilities of precise morphology design by deploying Au-Ni, a novel element combination for metal aerogels in itself, as a model system to combine common aerogel morphologies under one system for the first time. Au-Ni aerogels were synthesized via modified one- and two-step gelation, partially combined with galvanic replacement, to obtain aerogels with alloyed, heterostructural (novel metal aerogel structure of interconnected nanoparticles and nanochains), and hollow spherical building blocks. These differences in morphology are directly reflected in the physisorption behavior, linking the isotherm shape and pore size distribution to the structural features of the aerogels, including a broad-ranging specific surface area (35-65 m2 g-1). The aerogels were optimized regarding metal concentration, destabilization, and composition, revealing some delicate structural trends regarding the ligament size and hollow sphere character. Hence, this work significantly improves the structural tailoring of metal aerogels and possible up-scaling. Lastly, preliminary ethanol oxidation tests demonstrated that morphology design extends to the catalytic performance. All in all, this work emphasizes the strengths of morphology design to obtain optimal structures, properties, and (performances) for any material application.

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37674
Publ.-Id: 37674


Physics-Informed Machine Learning for Addressing Challenges in Static and Time-Dependent Density Functional Theory

Shah, K.; Cangi, A.

In this talk, we explore the potential of Physics-Informed Machine Learning (ML) in addressing
key computational tasks in both static and time-dependent Density Functional Theory (DFT
and TDDFT). The talk will focus on two projects that employ advanced ML techniques,
specifically Physics-Informed Neural Networks (PINNs) and Fourier Neural Operators (FNOs),
to tackle these complex tasks.
In the first part of the presentation, we examine the use of PINNs and FNOs in addressing the
intricate density-to-potential inversion problem in static DFT. By employing these methods as
alternatives to conventional inversion schemes, we demonstrate enhancements in predictive
transferability and speed. We highlight the applications to exactly solvable models, such as
soft-Coulomb systems, illustrating their potential as accurate and rapid data-driven surrogate
models.
In the second part of the talk, we discuss the application of PINNs to accelerate TDDFT
calculations. By incorporating the fundamental physical constraints of the Time-Dependent
Kohn-Sham equations directly into the learning process, PINNs offer a unique way to fuse the
power of deep learning with the nuances of TDDFT. We demonstrate the performance and
generalisability of PINN solvers on the time evolution of model systems across varying system
parameters, domains, and energy states.
By integrating physics and machine learning, these projects shed light on promising new
directions for addressing challenges in DFT and TDDFT. The methods developed here have
the potential to accelerate (TD)DFT workflows, enabling the simulation of large-scale
calculations of electron dynamics in matter exposed to strong electromagnetic fields, high
temperatures, and pressures.

  • Lecture (Conference)
    NHR Conference ’23, 18.-19.09.2023, Berlin, Germany

Permalink: https://www.hzdr.de/publications/Publ-37673
Publ.-Id: 37673


HELPMI: HElmholtz Laser-Plasma Metadata Initiative

Bagnoud, V.; Bussmann, M.; Debus, A.; Hornung, J.; Kaluza, M.; Kessler, A.; Pöschel, F.; Schlenvoigt, H.-P.; Schramm, U.; Eisenbarth, U.

HELPMI is a 2-year project, subsidized by the Helmholtz Metadata Collaboration, conducted by GSI, HI Jena and HZDR (lead). The aim is to start the development of a F.A.I.R. data standard for experimental data of the entire laser-plasma (LPA) community. Such standard does not yet exist. It will facilitate management and analysis of usually quite heterogeneous experimental data and logs by rich and machine-actionable metadata, allowing automated processing of broad and long data sets. To date, the LPA community is widely using openPMD, an open meta-standard, well-established for simulations. NeXus is a similarly hierarchical and extensible standard for various experimental methods of the Photon and Neutron science community. Within HELPMI, we plan to adopt NeXus for LPA experimental data and simultaneously to make openPMD and its API extensible for custom hierarchies like NeXus. Thereby we can achieve interoperability of the standards, circumventing the need for another standard. Alongside we will start developing a glossary of LPA experimental terms in order to achieve re-usability. The glossary shall be community-driven and technically open, extensible and implementation-independent.

Keywords: data standard; metadata; data management

  • Open Access Logo Lecture (Conference) (Online presentation)
    HMC Conference 2023, 10.-12.10.2023, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37672
Publ.-Id: 37672


Modified Diglycolamide Resin: Characterization and Potential Application for Rare Earth Element Recovery

Romero, J.; Tabelin, C. B.; Park, I.; Alorro, R. D.; Zoleta, J.; Silva, L. C.; Arima, T.; Igarashi, T.; Mhandu, T.; Ito, M.; Happel, S.; Hiroyoshi, N.

Rare earth elements (REEs) are crucial for green energy applications due to their unique properties, but their extraction poses sustainability challenges because the global supply of REEs is concentrated in a few countries, particularly China, which produces 70% of the world’s REEs. To address this, the study investigated TK221, a modified extraction chromatographic resin featuring diglycolamide (DGA) and carbamoyl methyl phosphine oxide (CMPO), as a promising adsorbent for REE recovery. The elemental composition and functional groups of DGA and CMPO on the polystyrene-divinylbenzene (PS-DVB) support of TK221 were confirmed using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). The adsorption kinetics of neodymium (Nd), yttrium (Y), cerium (Ce), and erbium (Er) followed the pseudo-second-order kinetic model and Langmuir isotherm, indicating monolayer chemisorption. Furthermore, iron (Fe) adsorption reached apparent equilibrium after 360 min, with consistent Fe adsorption observed at both 360 min and 1440 min. The inclusion of Fe in the study is due to its common presence as an impurity in most REE leachate solutions. The Fe adsorption isotherm results are better fitted with the Langmuir isotherm, implying chemisorption. Maximum adsorption capacities (qmax) of the resin were determined as follows: Nd (45.3 mg/g), Ce (43.1 mg/g), Er (35.1 mg/g), Y (15.6 mg/g), and Fe (12.3 mg/g). ATR-FTIR analysis after adsorption suggested that both C=O and P=O bands shifted from 1679 cm−1 to 1618 cm−1 and 1107 cm−1 to 1142 cm−1 for Y, and from 1679 cm−1 to 1607 cm−1 and 1107 cm−1 to 1135 cm−1 for Ce, implying possible coordination with REEs. These results suggest that TK221 has a huge potential as an alternative adsorbent for REE recovery, thus contributing to sustainable REE supply diversification.

Keywords: RARE EARTH ELEMENTS; EXTRACTION CHROMATOGRAPHY; ION-EXCHANGE RESIN; ADSORPTION; CRITICAL METALS

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Permalink: https://www.hzdr.de/publications/Publ-37671
Publ.-Id: 37671


Failure of load-bearing dyke networks as a trigger for volcanic edifice collapse

Thiele, S. T.; Cruden, A. R.; Micklethwaite, S.

Most large ocean-island volcanoes are gravitationally unstable. Some deform slowly, forming long-lived slumps, while others collapse and generate potentially dangerous debris avalanches. Here we investigate the effect of pervasive dyke networks on edifice instability, using data from La Palma, Spain. Like fibre-reinforced composites, where rigid layers are embedded in a compliant matrix, we find that dykes experience higher stress than surrounding host rocks. If the ratio of dyke to host stiffness is larger than the corresponding strength ratio, the dyke network will fail first, causing a rapid stress redistribution and possibly triggering edifice collapse. Fibre bundle models of a weak layer crosscut by dykes suggest this can occur with less seismicity or deformation than models without dykes. The models also suggest that dyke network strength could determine the potential for rapid collapse rather than gradual slump-type deformation. We conclude that dyke networks should be considered when assessing volcanic edifice stability.

Keywords: volcanic island; landslide; composite material; geohazards

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Permalink: https://www.hzdr.de/publications/Publ-37670
Publ.-Id: 37670


Curvilinear Antiferromagnetic Spin Chains: Interplay Between Geometry And External Magnetic Field

Borysenko, Y.; Sheka, D.; Yershov, K.; Faßbender, J.; van den Brink, J.; Makarov, D.; Pylypovskyi, O.

Antiferromagnetically ordered (AFM) spin chains arranged along space curves represent a useful playground to study various possibilities of altering the sample’s magnetic response by its geometry modification. The influence of curvature (κ) and torsion (τ) is characterized by effective magnetic interactions, namely anisotropic and Dzyaloshinskii–Moriya-like, which originate from exchange, dipolar interaction and intrinsic anisotropy [1, 2]. The strength of these interactions depends on κ and τ, determining the ground state and spin dynamics of such systems [2, 3].

Here, we investigate theoretically the interplay between geometrical and magnetic field effects in intrinsically achiral anisotropic spin chains shaped as rings (constant κ, no torsion) and helices (constant κ, τ) exposed to uniform static and rotating magnetic fields. Exposed to static magnetic field, bulk AFMs possess a high-field spin-flop state, characterized by reorientation of the order parameter. In contrast to the spin-flop phase for the model of a bulk easy-axis AFM, in ring-shaped spin chains the spin-flop state comprises two topologically different ground states depending on κ. We attribute them to the influence of curvature-induced Dzyaloshinskii–Moriya interaction, as well as the spin-flop transition being of first or second order depending on the ring curvature and the presence of an intermediate canted state for large κ [4]. In the helix-shaped spin chain, a rotating magnetic field induces domain wall propagation with velocity, which is proportional to the field frequency. The relation between the external field and geometrical parameters determines two motion modes: oscillating one and rigid motion with a constant velocity. Curvature and torsion strongly influence domain wall velocity and stability conditions of the rigid motion mode.

Keywords: antiferromagnetism; curvilinear antiferromagnets

  • Lecture (Conference)
    IEEE NAP 2023, 10.-15.09.2023, Bratislava, Solvakia

Permalink: https://www.hzdr.de/publications/Publ-37669
Publ.-Id: 37669


Modellierung des Stofftransportes in einer geneigten Kolonne mit dem Ansatz der hydrodynamischen Analogien

Ehlert, T.; Mamedov, T.; Schubert, M.; Kenig, E. Y.

Modellierung des Stofftransportes in einer geneigten Kolonne mit dem Ansatz der hydrodynamischen Analogien

  • Poster
    Jahrestreffen der ProcessNet Fachgruppen Fluidverfahrenstechnik und Hochdruckverfahrenstechnik, 02.-03.05.2022, Frankfurt am Main, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37667
Publ.-Id: 37667


Charakterisierung des Einflusses neigungsinduzierter Strömungsformen mit dem Ansatz der hydrodynamsichen Analogie

Ehlert, T.; Mamedov, T.; Schubert, M.; Kenig, E. Y.

Charakterisierung des Einflusses neigungsinduzierter Strömungsformen mit dem Ansatz der hydrodynamsichen Analogie

  • Poster
    Jahrestreffen der DECHEMA-Fachgruppen Fluidverfahrenstechnik und Adsorption, 21.-23.03.2023, Frankfurt, Germany

Permalink: https://www.hzdr.de/publications/Publ-37666
Publ.-Id: 37666


Friend or Foe? Microbial impact of Calcigel bentonite on metal materials used for nuclear waste repository

Wei, T.-S.; Sushko, V.; Matschiavelli, N.; Kluge, S.; Cherkouk, A.

Multi-barrier concept is a favorable option to store high-level nuclear waste (HLW) in a deep geological repository. Bentonites are processed clay materials that are considered as a geotechnical barrier for metal containers storing HLW. To understand the impact of indigenous microorganisms from bentonites on these metal materials, anaerobic microcosms incubating Calcigel bentonite, synthetic Opalinus clay (OPA) porewater, lactate (one of the organic acids in natural OPA porewater) or H2 gas (product from anaerobic metal corrosion) with or without cast iron metal plates were conducted for up to 9 months in triplicates for each condition and time point (sampling every 3 months).

The amplicon sequencing targeting V4 region of 16S rRNA genes showed that microbial communities of raw Calcigel bentonites mainly comprised phyla Acidobacteria, Actinobacteria, Chloroflexi, Firmicutes, Proteobacteria and Methylomirabilota. In the microcosms with lactate, enrichment of Bacillaceae (Firmicutes) and uncultured MB-A2-108 (Actinobacteriota) were observed; whereas in the presence of both lactate and cast iron, genera of Firmicutes, namely Desulfotomaculum, Desulfitobacterium and Desulfallas-Sporotomaculum, were highly enriched (relative abundance ranged from 60% to 95%) associating with large decrease in sulfate and lactate concentration. These bacteria appeared to be driven by H2 gas generated from metal corrosion. Moreover, SEM-EDX analyses showed that the metal surface was corroded and covered by a carbonate passivation layer. In this layer, FeS appeared to be formed, further suggesting the influence on cast iron corrosion and formation of secondary minerals induced by sulfate-reducing bacteria.

On the other hand, we supplied N2 gas mixed with H2 and CO2 (80:10:10) to stimulate growth of H2-oxidizing sulfate reducers. GC analyses showed that in the microcosms without cast iron, the content of H2 gas in the headspace decreased accompanying with decrease in sulfate concentration (measured via IC). However, in the microcosms with cast iron we noted large accumulation of H2 gas (~ 5 times more than initial value) and greater decrease in sulfate concentration. Similarly, surface corrosion was visible by SEM-EDX, and thre carbonate passivation layer with possible FeS precipitates was formed on the metal surface but in a shorter timeframe (3 months). Hence, we speculated that certain autotrophic H2-oxidizing sulfate reducers also corroded cast iron metal, and their taxonomy and mechanisms will be identified using metagenomic approaches.

Altogether we concluded that microbial communities in Calcigel bentonites lead to microbially induced corrosion for cast iron under certain conditions, yet interestingly, the formation of passivation layer enhances the resistance for further metal corrosion. The actual impact of indigenous microorganisms in different bentonites, either disadvantageous or beneficial, on metal containers for HLW requires comprehensive investigations.

Keywords: Bentonite; MIC; Corrosion; Nuclear waste repository; Sulfate-reducing bacteria; Cast iron

  • Open Access Logo Lecture (Conference)
    2nd Joint Symposium of the International Societies for Environmental Biogeochemistry & Subsurface Microbiology 2023, 22.-28.10.2023, Banff, Canada
    DOI: 10.3897/aca.6.e108081

Permalink: https://www.hzdr.de/publications/Publ-37665
Publ.-Id: 37665


Euler-Euler simulation of multi-regime two-phase flow with thin liquid films

Porombka, P.; Boden, S.; Schlottke, J.

Euler-Euler simulation of multi-regime two-phase flow with thin liquid films

Keywords: CFD; Euler-Euler two-fluid model; horizontal annular flow; liquid film; multi-regime modelling

  • Poster
    19th Multiphase Flow Conference and Workshop, 19.-23.06.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37664
Publ.-Id: 37664


High field suppression of bremsstrahlung emission in high-intensity laser-plasma interactions

Habibi, M.; Arefiev, A.; Toncian, T.

The interaction of high-intensity lasers with plasma is predicted to produce extreme quasi-static magnetic fields with magnitudes approaching Megatesla (MT) levels. In relativistically transparent plasmas, these fields can enhance direct laser acceleration and allow efficient gamma-ray emission by accelerated electrons. However, due to the so-called magnetic suppression effect, the magnetic field can also affect radiating electron trajectories and thus reduce the emission probability of the bremsstrahlung. This is the first study to examine the bremsstrahlung suppression mechanism in the context of high-intensity laser-plasma interactions. Our paper describes a new module that integrates the suppression effect into the standard bremsstrahlung module of the EPOCH particle-in-cell code by considering the impact of magnetic fields and extending the analysis to electric fields. We also investigate this suppressing mechanism's effect on the emitting electron's dynamics. Our findings show that this mechanism not only suppresses low-energy emissions but also has an impact on the dynamics of the radiating electrons.

Keywords: Bremsstrahlung emission; High field suppression; Relativistic transparency; High-intensity laser-plasma interaction

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37663
Publ.-Id: 37663


Experimental analysis of ship motion effects on the performance of an absorption column equipped with structured packings

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

In the upstream sector of the modern offshore industry, mainly packed columns are used for gas purification purposes, such as the removal of CO2, SOx, NOx, and other impurities. Offshore conditions are known for their harsh environment conditions that pose extra challenges for stable process operations and can lead to inefficient separation. To make use of the newly explored offshore energy resources, floating vessels, namely, Floating Production Storage and Offloading (FPSO) units, are currently gaining dominance due to their technological and economic advantages over conventional offshore platforms. These floating vessels with their unique design can be operated in deeper locations by means of advanced technologies, i.e. mooring system and remote control mechanisms. Despite aforementioned facts, the impact of sea states and strong winds on the floating production systems cannot be fully suppressed, and these conditions affect the performance of onboard packed columns. To have a highly efficient separation process, the interfacial mass transfer area between the gas and liquid phases in packed columns must be sufficiently large, and for this reason, a uniform distribution of the phases in characteristic packing channels is required. However, realizing uniform flow distribution in the packings becomes more difficult during ship motions. When considering the geometric arrangement of column internals, structured packings are likely to have relatively better performance than random packings under these circumstances. Nevertheless, it is still unclear to what extent the flow distribution deviates from its ideal pathway under motion conditions and how this deviation degrades the separation performance.
In this study, most predominant sea conditions are considered to experimentally analyze the effect of ship motions on the mass transfer efficiency of packed columns. Therefore, air dehumidification with triethylene glycol (TEG) desiccant is chosen as an example of an absorption process in a structured packing column. To simulate typical motion conditions, an absorption column (DN150) equipped with Mellapak 250Y structured packings is placed on the mobile platform of a hexapod robot that mimics the six-degree-of-freedom ship motion. The mass transfer performance of the absorption column in the stationary upright position is first investigated by measuring the inlet and outlet humidity of the gas phase, and then the experimental results in static and dynamic inclination positions are compared to evaluate the relative deterioration of the efficiency. Furthermore, the impact of operating conditions, such as gas factor, liquid load, and TEG concentration, is explored.

  • Poster
    Jahrestreffen der DECHEMA-Fachgruppen Fluidverfahrenstechnik und Adsorption, 21.-23.03.2023, Frankfurt, Germany

Permalink: https://www.hzdr.de/publications/Publ-37662
Publ.-Id: 37662


(Radio)metal interaction with selected biosystems - from nuclear waste repositories to the food chain

Raff, J.

The investigation of the interaction of radionuclides with biosystems plays an important role not only in repository research but also in radioecology. The obtained knowledge expands the basic understanding of the behavior of radionuclides in nature on the one hand and opens up possibilities for the industrial use of the processes on the other hand. The lecture will give a general overview of the research work in biogeochemistry and its application potential.

Keywords: radionuclides; repository research; radio ecology; biosystems

Related publications

  • Lecture (others)
    Institutsseminar, Department of Nuclear Chemistry, Czech Technical University, 05.10.2023, Prag, Tschechien

Permalink: https://www.hzdr.de/publications/Publ-37661
Publ.-Id: 37661


Understanding warm dense matter: from ab initio simulations to experiments

Dornheim, T.

Warm dense matter (WDM)---an extreme state that is characterized by extreme densities and
temperatures---has emerged as one of the most active frontiers in plasma physics and material
science. In nature, WDM occurs in astrophysical objects such as giant planet interiors and brown
dwarfs. In addition, WDM is highly important for cutting-edge technological applications such as
inertial confinement fusion and the discovery of novel materials. In the laboratory, WDM is studied
experimentally in large facilities around the globe, and new techniques have facilitated
unprecedented insights. Yet, the interpretation of these experiments requires a reliable diagnostics
based on accurate theoretical modeling, which is a notoriously difficult task [1].

In this work, I will give an overview of how we can use exact ab-initio path integral Monte Carlo
(PIMC) simulations [2] to get
new insights into the behavior of WDM. Moreover, I will show how switching to the imaginary-
time representation allows us to significantly improve the interpretation of X-ray Thomson
scattering (XRTS) experiments, which are a key diagnostic for WDM [3,4,5]. Specifically, I will show how new
PIMC capabilities will allow to give us novel insights into electronic correlations in warm dense
quantum plasmas, leading to unprecedented agreement between experiments [6] and theory.

[1] M. Bonitz et al., Physics of Plasmas 27, 042710 (2020)
[2] M. Böhme et al., Physical Review Letters 129, 066402 (2022)
[3] S. Glenzer and R. Redmer, Reviews of Modern Physics 81, 1625 (2009)
[4] T. Dornheim et al., Nature Communications 13, 7911 (2022)
[5] T. Dornheim et al., arXiv:2305.15305 (submitted)
[6] T. Döppner et al., Nature 618, 270-275 (2023)

  • Lecture (Conference)
    Big data and analytical methods for complex systems, 19.10.2023, Wroclaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-37660
Publ.-Id: 37660


Forschung für den Rückbau von Kernkraftwerken: Das Projekt KOBEKA

Hampel, U.

Während der Beprobung der Betonstrukturen des Reaktorgebäudes im Kernkraftwerk Stade wurden tief eingedrungene Kontaminationen im unteren Teil des Reaktorsicherheitsbehälters, der so genannten Betonkalotte, vorgefunden. Diese waren durch Primärkreiswasser aus verschiedenen Systemen während des Anlagenbetriebes eingetragen worden. Das Durchdringen der wasserabweisenden Dekontaminationsbeschichtung und die weitere Ausbreitung entlang von Arbeitsfugen hatten zu großräumiger Kontamination in der Größenordnung des bis zu 100-fachen der Freigabewerte geführt. Durch fehlende Detailkenntnisse zur Kontaminationsverteilung gestaltete sich der Rückbau erheblich zeit- und kostenaufwändiger als ursprünglich veranschlagt. Es ist davon auszugehen, dass dieses Problem andere Kernkraftwerke in Deutschland und weltweit betrifft.
Die Beprobung des Betons mittels Kernbohrungen ist durch erschwerte Zugänglichkeit des Beprobungsortes, baustatische Randbedingungen und Kosten eingeschränkt. Eine Alternative zu Kernbohrungen sind Bohrungen ins Volle. Wegen der schlankeren Bohrlöcher können deutlich mehr Bohrungen gesetzt werden, ohne die strukturelle Integrität des Reaktorgebäudes in unannehmbarem Maße zu schwächen. Allerdings fehlt es dann an Bohrkernen für eine Analytik. Das Vorhaben KOBEKA (gefördert durch das BMBF im Rahmen des Förderkonzeptes „FORKA - Forschung für den Rückbau kerntechnischer Anlagen“) beschäftigt sich daher mit der Entwicklung innovativer Messtechnik zur Beprobung und in-situ Messung in solchen schlanken Bohrlöchern. Entwickelt werden Technologien zur Detektion von Kontaminationen und zur Bestimmung des Nuklidvektors. Weiterhin sollen Feuchte und Porosität der Betonmatrix sowie die Präsenz von Borverbindungen ermittelt werden. Die Kenntnis der Porosität dient der Bestimmung der Lage von Arbeitsfugen, die Kenntnis des Feuchte- und Borgehalts geben Evidenz über eingedrungenes Primärkreiswasser. Zusätzlich ist die hydraulische Permeabilität zwischen verschiedenen Bohrungen von Interesse, um mögliche Transportwege über Arbeitsfugen zu identifizieren und damit die Beprobungsplanung zu unterstützen. Ebenfalls werden Werkzeuge zur Kartierung und elektronischen Dokumentation der Befunde entwickelt.

Keywords: Rückbau von Kernkraftwerken

  • Lecture (Conference)
    55. Kraftwerkstechnisches Kolloquium, 10.-11.10.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37658
Publ.-Id: 37658


Ultrafast X-ray tomography and its application to studying particle flows

Hampel, U.; Barthel, F.; Baecke, A. M.; Bieberle, A.; Bieberle, M.; Lecrivain, G.; Papapetrou, T. N.; Windisch, D.

Ultrafast X-ray tomography is a key imaging technique for multiphase flows. In particular, it has been used with great success for studying particle flows. Here, we give an overview of recent developments in the scanner hardware and data processing, and demonstrate the use of this technique to the study of particle segregation in a rotating drum as an exemplary test case for analysing industrial particle mixing systems.

Keywords: Ultrafast X-ray tomography; Particle flow; Mixing and segregation

  • Contribution to proceedings
    11th World Congress on Industrial Process Tomography (WCIPT-11), 06.-08.09.2023, Mexico City, Mexico
  • Lecture (Conference)
    11th World Congress on Industrial Process Tomography (WCIPT-11), 06.-08.09.2023, Mexico City, Mexico

Permalink: https://www.hzdr.de/publications/Publ-37657
Publ.-Id: 37657


Entwicklung von Messtechnik zur Beprobung kontaminierter Betonstrukturen im Sicherheitsbehälter von Druckwasserreaktoren während des Kraftwerksrückbaus (KOBEKA)

Bertram, W.; Hampel, U.; Anthofer, A.; Dirk Döhler, D.; Herrmann, M.; Jansen, S.; Kahle, P.; Kormoll, T.; Kosowski, K.; Lösch, H.; Mechtcherine, V.; Nurjahan, T.; Rauf, A.; Reinecke, A.-M.; Schleicher, E.; Schröfl, C.; Werner, T.

Während der Beprobung der Betonstrukturen des Reaktorgebäudes im Kernkraftwerk Stade wurden tief eingedrungene Kontaminationen im unteren Teil des Reaktorsicherheitsbehälters, der so genannten Betonkalotte, vorgefunden. Diese waren durch Primärkreiswasser aus verschiedenen Systemen während des Anlagenbetriebes eingetragen worden. Das Durchdringen der wasserabweisenden Dekontaminationsbeschichtung und die weitere Ausbreitung entlang von Arbeitsfugen hatten zu großräumiger Kontamination in der Größenordnung des bis zu 100-fachen der Freigabewerte geführt. Durch fehlende Detailkenntnisse zur Kontaminationsverteilung gestaltete sich der Rückbau erheblich zeit- und kostenaufwändiger als ursprünglich veranschlagt. Es ist davon auszugehen, dass dieses Problem andere Kernkraftwerke in Deutschland und weltweit betrifft.
Die Beprobung des Betons mittels Kernbohrungen ist durch erschwerte Zugänglichkeit des Beprobungsortes, baustatische Randbedingungen und Kosten eingeschränkt. Eine Alternative zu Kernbohrungen sind Bohrungen ins Volle. Wegen der schlankeren Bohrlöcher können deutlich mehr Bohrungen gesetzt werden, ohne die strukturelle Integrität des Reaktorgebäudes in unannehmbarem Maße zu schwächen. Allerdings fehlt es dann an Bohrkernen für eine Analytik. Das Vorhaben KOBEKA (gefördert durch das BMBF im Rahmen des Förderkonzeptes „FORKA - Forschung für den Rückbau kerntechnischer Anlagen“) beschäftigt sich daher mit der Entwicklung innovativer Messtechnik zur Beprobung und in-situ Messung in solchen schlanken Bohrlöchern. Entwickelt werden Technologien zur Detektion von Kontaminationen und zur Bestimmung des Nuklidvektors. Weiterhin sollen Feuchte und Porosität der Betonmatrix sowie die Präsenz von Borverbindungen ermittelt werden. Die Kenntnis der Porosität dient der Bestimmung der Lage von Arbeitsfugen, die Kenntnis des Feuchte- und Borgehalts geben Evidenz über eingedrungenes Primärkreiswasser. Zusätzlich ist die hydraulische Permeabilität zwischen verschiedenen Bohrungen von Interesse, um mögliche Transportwege über Arbeitsfugen zu identifizieren und damit die Beprobungsplanung zu unterstützen. Ebenfalls werden Werkzeuge zur Kartierung und elektronischen Dokumentation der Befunde entwickelt.

Keywords: Rückbau von Kernkraftwerken

  • Contribution to proceedings
    KONTEC 2023: Internationales Symposium „Konditionierung radioaktiver Betriebs- und Stilllegungsabfälle“, 30.08.-01.09.2023, Dresden, Deutschland
  • Lecture (Conference)
    KONTEC 2023: Internationales Symposium „Konditionierung radioaktiver Betriebs- und Stilllegungsabfälle“, 30.08.-01.09.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37656
Publ.-Id: 37656


Efficient ultrafast field-driven spin current generation for spintronic terahertz frequency conversion (raw data in Origin project)

Ilyakov, I.; Brataas, A.; de Oliveira, T.; Ponomaryov, A.; Deinert, J.-C.; Hellwig, O.; Faßbender, J.; Lindner, J.; Salikhov, R.; Kovalev, S.

In this Origin project file (*.opju) we provide an access to the raw data which we obtained and analyzed. The result of our analysis are presented in the publication "Efficient ultrafast field-driven spin current generation for spintronic terahertz frequency conversion".

Keywords: spin current; spintronics; terahertz frequency conversion; high THz field

Related publications

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Permalink: https://www.hzdr.de/publications/Publ-37655
Publ.-Id: 37655


High Field Suppression of Bremsstrahlung Emission in High-Intensity Laser-Plasma Interactions

Habibi, M.; Toncian, T.
Project Leader: Toncian, Toma

This dissertation investigates the effect of macroscopic electric and magnetic fields on bremsstrahlung emission in high-intensity laser-plasma interactions, specifically in the regime of relativistic-induced transparency. The Particle-in-Cell (PIC) EPOCH simulation code has been updated to incorporate a new suppression mechanism influenced by the presence of intense electric and magnetic fields. The study compared the bremsstrahlung emissions generated under relativistic transparency conditions using three distinct models: the original bremsstrahlung model in the EPOCH code, the model modified by the magnetic suppression (MS) effect, and the newly proposed suppression model by the electric and magnetic suppression (EMS) effect.
The results demonstrated that macroscopic electric and magnetic fields have a significant effect on the decrease of bremsstrahlung photons in laser-plasma interactions. In addition, differences in electron dynamics were observed between the EPOCH and EMS models, indicating that the suppression mechanism can influence the dynamics of electron acceleration. The study provides insight into bremsstrahlung emission under extreme conditions, where energetic electrons travel through a relativistically transparent plasma while being deflected by magnetic fields with MT-level strength.
On the basis of the results, it is suggested that the implementation of conventional bremsstrahlung in PIC codes be modified to account for the discussed suppression effect.

Keywords: EPOCH; PIC code; EMS model; Bremsstrahlung Suppression; Relativistic Transparency

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Permalink: https://www.hzdr.de/publications/Publ-37654
Publ.-Id: 37654


Monitoring Pancreatic α-Amylase of Postoperative Patients with Droplet-Based Microfluidics

Zhao, X.; Kolbinger, F. R.; Distler, M.; Weitz, J.; Makarov, D.; Bachmann, M.; Baraban, L.

This study presents a groundbreaking portable droplet-based microfluidic device capable of real-time detecting α-amylase activity in drainage fluids for postoperative patient monitoring. By implementing this strategy, the determination time for α-amylase levels is significantly reduced from several hours, the current clinical standard, to just three minutes.1 The device demonstrates a remarkable improvement in detection sensitivity, reaching a detection limit of 7 nmol/s·L, an order of magnitude enhancement compared to the recent state of the art.2 Moreover, a mere 10 μL of drain liquid and reagent are necessary for each measurement reducing material requirement and waste.3,4 Crucially, this real-time continuous detection strategy circumvents delays in diagnosis, ensuring prompt treatment of life-threatening complications. Figure 1A illustrates the schematic representation of real-time α-amylase detection in the microfluidic device. A minute volume of patient exudate is continuously gathered and enclosed with a starch reagent within 200 nL droplets. The emitted fluorescence intensity is monitored as a measure of α-amylase activity. Distinct fluorescence intensities were emitted when various concentrations of standard amylase solutions reacted with a fixed quantity of reagent, as shown in Figure 1B, by which the calibration curve is obtained (Figure 1C). A total of 32 patient samples were assessed, and the amylase concentration was determined using the established calibration curve. Evaluation of the results, as depicted in Figure 1D, reveals the dependable detection accuracy of the droplet-based microfluidic device compared to clinical gold-standard methods.

  • Open Access Logo Poster
    The 27th International Conference on Miniaturized Systems for Chemistry and Life Sciences (µTAS 2023), 15-19 October 2023 Katowice, Poland, 15.-19.10.2023, Katowice, Poland

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Permalink: https://www.hzdr.de/publications/Publ-37653
Publ.-Id: 37653


Towards Data-Driven Optimization of Experiments in Photon Science

Kelling, J.; Willmann, A.; Thiessenhusen, E.; Rustamov, J.; Aguilar, R. A.; Hänel, T.; Hoffmann, N.; Debus, A.; Juckeland, G.; Bachmann, M.

High-fidelity (computer-) experiments are very expensive to perform, hence
extracting as much information as possible from the collected data is vital.
We present methods to estimate experiment outcomes based on ingested past data,
to steer further sample acquisition both by suggesting paths for maximized
uncertainty reduction and highlighting sensitivities on inputs, with use-cases
from laser-light propagation and laser-plasma interactions to electron-bunch
kinetics.

Keywords: surrogate models; machine learning; digital twins; laser-plasma accelerators; free-electron laser

  • Open Access Logo Invited lecture (Conferences)
    9th Annual MT meeting, 09.-11.10.2023, Karlsruhe, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-37652
Publ.-Id: 37652


Defect Engineering of Ta3N5 Photoanodes: Enhancing Charge Transport and Photoconversion Efficiencies via Ti Doping

Wagner, L. I.; Sirotti, E.; Brune, O.; Grötzner, G.; Eichhorn, J.; Santra, S.; Munnik, F.; Olivi, L.; Pollastri, S.; Streibel, V.; Sharp, I. D.

Ta3N5 shows great potential as a semiconductor photoanode for solar water splitting. However, its performance is hindered by poor charge carrier transport and trapping due to a high density of defects that introduce electronic states deep within its bandgap. Here, we demonstrate that controlled Ti doping of Ta3N5 can dramatically reduce the concentration of deep-level defects and enhance its photoelectrochemical performance, yielding a sevenfold increase in photocurrent density and a 300 mV cathodic shift in photocurrent onset potential compared to undoped material. Comprehensive characterization reveals that Ti+4 ions substitute Ta+5 lattice sites, thereby introducing compensating acceptor states, reducing concentrations of nitrogen vacancies and reduced Ta+3 states, and thereby suppressing trapping and recombination. Importantly, Ti doping offers distinct advantages compared to Zr, an intensively investigated dopant of Ta3N5 in the same group of the periodic table. Specifically, Ti+4 and Ta+5 have more similar atomic radii, allowing for substitution without introducing lattice strain, and Ti exhibits a lower affinity for oxygen than Zr, enabling its incorporation without increasing the oxygen donor content. Consequently, we demonstrate that the electrical conductivity can be tuned by over seven orders of magnitude. Thus, Ti doping in Ta3N5 provides a powerful basis for precisely engineering the optoelectronic characteristics of Ta3N5 and to substantially improve its functional characteristics as an advanced photoelectrode for solar fuels applications.

Keywords: solar water splitting; tantalum nitride (Ta3N5); doping; defect engineering; charge carrier engineer

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37651
Publ.-Id: 37651


FVV1455: CFD Simulation of Droplet Separators

Singh, D.; Boden, S.; Schlegel, F.
Producer: Schlottke, Jan; Producer: Weber, Andreas

For industrial applications, the two-fluid model is preferred due to its efficient modelling of small-scale interfaces. Whereas, a thin film model, based on a long wave approximation, is used for the unresolved interfaces to obtain the film features by solving the 2D Navier-Stokes equations for wall films. Within the project, the target is to develop an experimentally validated 3D-CFD model to investigate the separation efficiency of droplet separators for fuel cell systems. A hybrid model is developed, which couples the two-fluid model with a thin film model via mass transfer terms for droplet deposition, droplet entrainment and film separation. A two-way coupling between droplets and the thin film is established using mass and momentum source terms, derived analytical and from available experiments. The droplet separator is an essential component of an automotive fuel cell system that segregates a significant amount of liquid fractions from the air-water mixture. The flow dynamics inside a droplet separator consist of a dispersed gas and liquid with a wall adhered thin liquid film. The modelling is divided into the following stages due to the complex fluidic phenomenon inside a generic droplet separator:

  1. Droplet deposition model,
  2. Film separation model,
  3. Film transition model, and
  4. Population balance model.

The numerical simulations are validated and fine-tuned with experiments carried out at HZDR.

Keywords: Numerical Simulation; Droplets; Film Modeling; Multiphase Flow; Fuel Cell; Separation; Automotive

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Permalink: https://www.hzdr.de/publications/Publ-37650
Publ.-Id: 37650


Interfacial selective separation of fine particles for the recycling of PEM electrolyzer exploiting particle-fluid interactions in multiphase systems

Ahn, S.; Rudolph, M.

For large-scale of green hydrogen production via water electrolysis, catalysts containing critical materials in a submicron down to nanometer scale have advantages as active materials in the application. The circularity of critical raw materials such as PGM after the utilization phase becomes and thus recycling processes for end-of-life water electrolyzers need to be developed.
In the range of ultra-fine particle systems (0.1 to 10 µm), established techniques like flotation have challenges for their efficient separation. Liquid-liquid phase transfer is one possible alternative approach for the selective separation of such fine particles. In this phase transfer process, the interactions between particles and oil droplets are greater than those between particles and air bubbles in classic flotation. Hence, particles can be enriched much more efficiently at the oil-water interfaces.
In this study, titanium oxide TiO2 and carbon black are separated representing anode and cathode material in polymer electrolyte membrane (PEM) water electrolyzer respectively. Wettability characterization studies revealed their significant contrast in hydrophobicity. TiO2 exhibits a rather hydrophilic surface while carbon black shows hydrophobic characteristic, however there are still many unknown properties of the surface characteristics of various carbon black variants.
By using the analytic particle solvent extraction (APSE) method, particle mixtures can be transferred into organic and aqueous phases respectively, and selectively separated with high recovery. This approach provides a contribution to scale-up the recycling processes of PEM water electrolyzers.

Keywords: Fine particles; Recycling; Particle separation; PEM water electrolyzer; Wettability

  • Lecture (Conference)
    Jahrestreffen der DECHEMA-Fachgruppen Kristallisation, Grenzflächenbestimmte Systeme und Prozesse sowie Mechanische Flüssigkeitsabtrennung, 09.-10.03.2023, Frankfurt am Main, Germany

Permalink: https://www.hzdr.de/publications/Publ-37649
Publ.-Id: 37649


Application of particle-fluid interactions for selective separation of fine particles for the recycling of HTEL electrolyzer

Ahn, S.; Rudolph, M.

For efficient renewable energy circulation, hydrogen production via water electrolysis technology has been developed over past decades. Amongst three technologies, high temperature water electrolysis (HTEL) is considered as a promising technology because of its high efficiency. Rare earth elements are the best candidates to make the cell more promising. However, reaching a long-term operation is an unsolved challenge because the durability of used ceramic materials is still an issue. Hence, development of the recycling processes for these critical raw materials is an important topic.
Ceramic materials used in HTEL cell have a similar surface property in terms of wettability. For this reason, fine particles cannot be separated without help from surfactants. In this study, representative materials such as Nickel oxide (NiO), Lanthanum strontium manganite (LSM), Yttria stabilized zirconia (YSZ), and Zirconium (ZrO2) oxide are used and their surface charge are investigated. Depending on the pH value, materials show change of their surface charge. Considering their electric charge, different surfactants applied to drive the particle surface hydrophobic. Since NiO and LSM have positive surface charge in base dispersion, particles may be hydrophobized with anion surfactant. Wettability of the YSZ and ZrO2, materials with opposite surface charge, changed by addition of cation surfactant. Their changed wettability can be described by using particle attachment on single air bubbles. Additional approach by using liquid-liquid phase transfer explain their behavior at the oil-water interfaces. This approach provides a contribution to scale-up the recycling processes of HTEL cells.

Keywords: Fine particles; Recycling; Particle separation; Interfaces; high temperature electrolyzer

  • Lecture (Conference)
    14th European Congress of Chemical Engineering and 7th European Congress of Applied Biotechnology, 17.-21.09.2023, Berlin, Germany

Permalink: https://www.hzdr.de/publications/Publ-37648
Publ.-Id: 37648


Application of novel hydrophobic binders for the selective agglomeration of fine particles for the recycling of PEM water electrolyzers

Ahn, S.; Rudolph, M.

With the tremendous increase of hydrogen production via water electrolysis technology, the development of a recycling process for valuable raw materials is emerging as an important issue for a functional circular economy. Especially, platinum group metals such as Iridium oxide and platinum particles on carbon black are used as active materials in the polymer electrolyte membrane (PEM) water electrolyzer. Since the size range of those particles is well below 100 µm, the development of mechanical separation technologies has not been well established. Conventional mechanical separation processes, such as flotation, are not effective for particles in the submicron scale.
According to previous investigations, each material on both electrodes shows a contrast in surface properties in terms of (de)wett(ing)ability. Cathode materials such as carbon black exhibit a hydrophobic character, while anode materials like Iridium oxide show a rather good affinity for water. For this study, pure particle fractions of carbon black and titanium oxide are used as representative materials.
Oil agglomeration is one of the widespread technologies to recover hydrophobic particles. As reported by Kim Van Netten in 2017, the separation of fine coal particles from a suspension was achieved by using a new type of hydrophobic binder comprising only 5 % of organic liquid. In this study, this novel organic emulsion system is applied to separate ultra-fine carbon black particles selectively and to assess the functionality of the emulsion to develop a process for PEM recycling. Those water-in-oil-in-water emulsion droplets enable to reach the agglomeration of carbon black particles in a few seconds which is a promising pre-treatment result for subsequent enrichment.

Keywords: Fine particles; Wettability; Recycling; PEM water electrolyzer

  • Poster
    PARTEC 2023, International Congress on Particle Technology, 26.-28.09.2023, Nürnberg, Germany

Permalink: https://www.hzdr.de/publications/Publ-37647
Publ.-Id: 37647


Development of Fine Particle Mechanical Separation Processes with Representative Catalyst Materials for Recycling PEM Water Electrolyzers Exploiting their Wetting Characteristics

Ahn, S.; Rudolph, M.

Demand for technologies using water electrolysis to produce green hydrogen is increasing, although recycling research on membrane electrode assemblies, which contain various precious and highly critical metals, is still limited. This study therefore aims at exploiting the feasibility of fine particle separation processes based on the difference in hydrophobicity of the ultrafine materials used as catalysts in polymer electrolyte membrane electrolyzers and at providing a fundamental study with representative materials of carbon black and TiO2. Since the cathode materials including carbon black are hydrophobic and the anode materials as well as TiO2 are hydrophilic, the characterizations of their various surface properties such as zeta potentials, dispersion characteristics, and bubble coverage angle tests have been investigated. In addition, using liquid-liquid particle extraction in a mixture model, 99 % of carbon black is recovered in the organic phase and 97 % of TiO2 is selectively separated in the aqueous phase with the help of the dispersant, sodium hexametaphosphate.

Keywords: Fine particles; Interfaces; PEM water electrolyzer; Surface chemistry; Wettability

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Permalink: https://www.hzdr.de/publications/Publ-37646
Publ.-Id: 37646


Preparation of 18F-Labeled Tracers Targeting Fibroblast Activation Protein via Sulfur [18F]Fluoride Exchange Reaction

Craig, A.; Kogler, J.; Laube, M.; Ullrich, M.; Donat, C.; Wodtke, R.; Kopka, K.; Stadlbauer, S.

Early detection and treatment of cancers can significantly increase patient prognosis and enhance the quality of life of affected patients. The emerging significance of the tumor microenvironment (TME) as a new frontier for cancer diagnosis and therapy may be exploited by radiolabeled tracers for diagnostic imaging techniques such as positron emission tomography (PET). Cancer-associated fibroblasts (CAFs) within the TME are identified by biomarkers such as fibroblast activation protein alpha (FAPα), which are expressed on their surfaces. Targeting FAPα using small molecule 18F-labeled inhibitors (FAPIs) have recently garnered significant attention for non-invasive tumor visualization using PET. Currently, the predominant 18F-fluorination method for radiolabeling FAPIs involves chelation-based radiofluorination strategies using aluminum [18F]fluoride ([18F]AlF). Herein, a powerful radiofluorination protocol for the preparation of two 18F-labeled FAPIs via the sulfur [18F]fluoride exchange ([18F]SuFEx) reaction and preliminary biological evaluation is disclosed.

Keywords: Automation; cancer-associated fibroblast; FAPI; 18F-fluorination; positron emission tomography (PET); [18F]SuFEx

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Permalink: https://www.hzdr.de/publications/Publ-37644
Publ.-Id: 37644


Data publication: Influence of oxidic and metallic interfaces on the magnetic damping of Permalloy thin films

Ney, V.; Salikhov, R.; Lenz, K.; Hellwig, O.; Lindner, J.; Ney, A.

FMR Rohdaten und Auswertungen.

Keywords: Thin films; ferromagnetism; ferromagnetic resonance; anisotropy; linewidth

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Permalink: https://www.hzdr.de/publications/Publ-37643
Publ.-Id: 37643


Data publication: Magnetic State Control of Non-van der Waals 2D Materials by Hydrogenation

Barnowsky, T.; Curtarolo, S.; Krasheninnikov, A.; Heine, T.; Friedrich, R.

This dataset includes the primary research data for the publication "Magnetic State Control of Non-van der Waals 2D Materials by Hydrogenation".

Keywords: 2D materials; magnetism; non-van der Waals compounds; passivation; data-driven research; computational materials science; high-throughput computing

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Permalink: https://www.hzdr.de/publications/Publ-37642
Publ.-Id: 37642


A Monte Carlo photonic model to simulate the UV inactivation of airborne microorganisms

Cavagnola, M. A.; Hampel, U.; Lecrivain, G.

A model based on a photonic approach is developed, that allows us to track each of the flowing airborne microorganisms and predict, by using a kinetic Monte Carlo algorithm, whether it is active or not.

  • Poster
    HZDR - PhD seminar, 17.-19.10.2023, Rittergut Schilbach, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37641
Publ.-Id: 37641


Data publication: Control of Four-Magnon Scattering by Pure Spin Current in a Magnonic Waveguide

Hache, T.; Körber, L.; Hula, T.; Lenz, K.; Kakay, A.; Hellwig, O.; Lindner, J.; Faßbender, J.; Schultheiß, H.

This dataset contains the numerical and experimental data (both raw and evaluated), labbooks associated with the measurements for our paper published in Physical Review Applied.

Keywords: spin waves; magnetism; BLS; four-magnon scattering; spin current; spintronics; magnonics

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Permalink: https://www.hzdr.de/publications/Publ-37640
Publ.-Id: 37640


Investigations on the Eu(III) translocation in hydroponically grown plants

Klotzsche, M.; Steudtner, R.; Vogel, M.; Drobot, B.; Schymura, S.; Raff, J.

Lanthanides (Ln) have become indispensable for science, technology and everyday objects. The intense
exploitation of Ln-bearing ores, their further processing as well as the improper disposal of high-tech
products lead to anthropogenic increased levels of these metals in the environment. Knowledge about their
fate in the plant biosphere is crucial to maintain food safety and to develop feasible phytoremediation
strategies.
In our research, we aim to follow Eu(III) on its journey through hydroponically grown sand oat (Avena
strigosa) – a potential candidate for phytoremediation – from initial exposure and cellular uptake over
localization in root tissue followed by translocation via plant sap into aboveground parts and the metal’s
distribution in leaves. Therefore, we apply a set of spectroscopic (TRLFS, ICP-MS), microscopic (chemical
microscopy), chromatographic (HPLC) and photographic (autoradiography) analysis techniques. In short,
following an exposure time of 96 h with 200 μM Eu(III), chemical microscopy reveals roots hairs and root
tips a s well as epidermis cells to be one uptake pathway for the Ln. Quantification of the metal content in
roots and shoots by ashing and subsequent acid digestion unveils that the majority of Eu(III) accumulates
in the roots (≈14242 μg/gdry weight) whereas only 35 μg/gdry weight) is translocated into the green plant parts.
The upwards transport of Eu(III) takes place via the xylem sap, in which organic acids are probably
responsible for Eu(III) translocation in measurable quantity. In order to visualize not solely the microscopic
distribution of Eu(III) in roots, but also account for the shoots, experiments with the radioactive isotope
Eu-152 were conducted and the dried plant was scrutinized by autoradiography (Fig. 1).
These studies contributed to a comprehensive understanding of the fate of Ln(III) in plants. Investigations
regarding the uptake and distribution of Cm(III) are currently under way.

Keywords: bioassociation; europium; lanthanide; plant; chemical microscopy

  • Lecture (Conference)
    21st Jena Remediation Symposium, 05.-06.10.2023, Jena, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37639
Publ.-Id: 37639


Saturation of the anomalous Hall effect at high magnetic fields in altermagnetic RuO2

Tschirner, T.; Keßler, P.; Gonzalez Betancourt, R. D.; Kotte, T.; Kriegner, D.; Büchner, B.; Dufouleur, J.; Kamp, M.; Jovic, V.; Smejkal, L.; Sinova, J.; Claessen, R.; Jungwirth, T.; Moser, S.; Reichlova, H.; Veyrat, L.

Observations of the anomalous Hall effect in RuO2 and MnTe have demonstrated unconventional time-reversal symmetry breaking in the electronic structure of a recently identified new class of compensated collinear magnets, dubbed altermagnets. While in MnTe, the unconventional anomalous Hall signal accompanied by a vanishing magnetization is observable at remanence, the anomalous Hall effect in RuO2 is excluded by symmetry for the Néel vector pointing along the zero-field [001] easy-axis. Guided by a symmetry analysis and ab initio calculations, a field-induced reorientation of the Néel vector from the easy-axis toward the [110] hard-axis was used to demonstrate the anomalous Hall signal in this altermagnet. We confirm the existence of an anomalous Hall effect in our RuO2 thin-film samples, whose set of magnetic and magneto-transport characteristics is consistent with the earlier report. By performing our measurements at extreme magnetic fields up to 68 T, we reach saturation of the anomalous Hall signal at a field Hc ≃ 55 T that was inaccessible in earlier studies but is consistent with the expected Néel-vector reorientation field.

Permalink: https://www.hzdr.de/publications/Publ-37638
Publ.-Id: 37638


Composition-dependent absorption of radiation in semiconducting MSi2Z4 Monolayers

Muhammad, S. R.; Tomasz, W.; Kuc, A. B.; Caterina, C.

The recent synthesis of MoSi2N4 material, along with theoretical predictions encompassing the entire family of chemical analogs, has opened up a new array of low-dimensional materials for a diverse range of optoelectronics and photovoltaics applications. In this study, we conducted state-of-the-art many-body first-principles calculations to analyze the quasi-particle electronic structure of the material class MSi2Z4 (where M = Mo, W, and Z = N, P, As, Sb). All monolayers display a direct band gap at the K point, with the exception of MoSi2N4. In tungsten-based compounds, the fundamental-gap can be adjusted over a significantly broader energy range compared to their molybdenum-based counterparts. Additionally, increasing atomic weight of the Z, both the band gap and exciton binding energies decrease. A noteworthy feature is the absence of a lateral valley (Λ or Q) near the conduction band minimum, indicating potential higher photoluminescence efficiencies compared to conventional transition-metal dichalcogenide monolayers. The optical spectra of these materials are predominantly characterized by tightly bound excitons, leading to an absorption onset in the visible range (for N-based) and in the infrared region (for others). This diversity offers promising opportunities to incorporate these materials and their heterostructures into optoelectronic devices, with tandem solar cells being particularly promising.

Permalink: https://www.hzdr.de/publications/Publ-37637
Publ.-Id: 37637


Understanding warm dense matter: from ab initio simulations to experiments

Dornheim, T.

Warm dense matter (WDM)---an extreme state that is characterized by extreme densities and
temperatures---has emerged as one of the most active frontiers in plasma physics and material
science. In nature, WDM occurs in astrophysical objects such as giant planet interiors and brown
dwarfs. In addition, WDM is highly important for cutting-edge technological applications such as
inertial confinement fusion and the discovery of novel materials. In the laboratory, WDM is studied
experimentally in large facilities around the globe, and new techniques have facilitated
unprecedented insights. Yet, the interpretation of these experiments requires a reliable diagnostics
based on accurate theoretical modeling, which is a notoriously difficult task [1].

In this work, I will give an overview of how we can use exact ab-initio path integral Monte Carlo
(PIMC) simulations [2] to get
new insights into the behavior of WDM. Moreover, I will show how switching to the imaginary-
time representation allows us to significantly improve the interpretation of X-ray Thomson
scattering (XRTS) experiments, which are a key diagnostic for WDM [3]. Specifically, I will
present a model-free temperature diagnostic [4] based on the well-known principle of detailed
balance, but available for all wave numbers, and a new idea to directly extract the electron—
electron static structure factor from an XRTS measurement [5]. As an outlook, I will show how new
PIMC capabilities will allow to give us novel insights into electronic correlations in warm dense
quantum plasmas, leading to unprecedented agreement between experiments [6] and theory.

[1] M. Bonitz et al., Physics of Plasmas 27, 042710 (2020)
[2] M. Böhme et al., Physical Review Letters 129, 066402 (2022)
[3] S. Glenzer and R. Redmer, Reviews of Modern Physics 81, 1625 (2009)
[4] T. Dornheim et al., Nature Communications 13, 7911 (2022)
[5] T. Dornheim et al., arXiv:2305.15305 (submitted)
[6] T. Döppner et al., Nature 618, 270-275 (2023)

  • Lecture (Conference)
    The 9th annual meeting of the programme "Matter and Technologies", 09.-11.10.2023, Karlsruhe, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37636
Publ.-Id: 37636


Implementing code review in the scientific workflow: Insights from ecology and evolutionary biology

Ivimey-Cook, E. R.; Pick, J. L.; Bairos-Novak, K. R.; Culina, A.; Gould, E.; Grainger, M.; Marshall, B. M.; Moreau, D.; Paquet, M.; Royauté, R.; Sánchez-Tójar, A.; Simoes Silva, I. M.; Windecker, S. M.

Code review increases reliability and improves reproducibility of research. As such, code review is an inevitable step in software development and is common in fields such as computer science. However, despite its importance, code review is noticeably lacking in ecology and evolutionary biology. This is problematic as it facilitates the propagation of coding errors and a reduction in reproducibility and reliability of published results. To address this, we provide a detailed commentary on how to effectively review code, how to set up your project to enable this form of review and detail its possible implementation at several stages throughout the research process. This guide serves as a primer for code review, and adoption of the principles and advice here will go a long way in promoting more open, reliable, and transparent ecology and evolutionary biology.

Keywords: ecology; evolutionary biology; open science; reliability; reproducibility; research process; software development; coding errors

Permalink: https://www.hzdr.de/publications/Publ-37635
Publ.-Id: 37635


Numerical modelling and simulation of electric heater for thermal energy storage system

Bouldorie, J.; Bangalore Mohankumar, M.

As a part of my graduation in engineering school in France and master’s degree, I am doing
my 6-month internship/master thesis in the Helmholtz-Zentrum Dresden-Rossendorf in the Institute
of Fluid Dynamics. The team comprised of my supervisor and PhD student, Mrs. Malini Bangalore
Mohankumar, Dr. Sebastian Unger, PhD student Alexandre Guille Bourdas, and I, is working on a
project of Thermal Energy Storage (TES). This system would store the surplus of electricity when
the production is higher than the demand. The electricity is used in order to heat a storage material.
Indeed, an electrical heater heats a CO2 flow, which will through a tank heating the storage material.
The electrical heater is the subject of my work and thesis.
The choice of the fluid was already determined: the CO2 at atmospheric pressure, as it is non
toxic, non inflammable, low corrosive and has advantageous thermodynamic properties.
Nevertheless, other fluids will be studied in the future. Furthermore, the mass flow rate and the
temperatures are fixed by the process of the other systems, such as the thermal storage cycle and the
power cycle. The mass flow rate is 5 kg/s and the inlet/outlet temperatures are 400°C/1000°C. These
are the only constraints for designing the heater. Then different sizes, geometries of the heater will
be studied in order to determine the configuration of the heater.
In this aim, a review of heaters and heat transfer in the shell part of shell-and-tube heat
exchangers is developed. In fact, few articles are available on the operation of electrical heaters at
high temperature. Moreover, shell-and-tube heat exchangers work in the same way as the heater.
However, the range of temperatures differs, so some work has to be done in order to model the heat
transfer in the heater.
With this in mind, an analytical work is developed, in order to have an order of magnitude of
the heat transfer. In this part, different models and correlations are used, to have a first estimation of
the heater length.
Then, a simulation approach applying numerical methods, such as Computational Fluid
Dynamics (CFD) is done. This approach, allows to determine more accurate results, which include
radiation. However, a focus is necessary on the validity of the model of resolution/radiation on the
software.
Finally, to optimize the heat transfer performance in the heater, the results of different designs
are compared,

Keywords: Thermal energy storage; Supercritical CO2; electrical heater

  • Master thesis
    University of Poitiers, France, 2023
    Mentor: Malini Bangalore Mohankumar
    102 Seiten

Permalink: https://www.hzdr.de/publications/Publ-37634
Publ.-Id: 37634


Metal Deportment in Complex Secondary Raw Materials: The Case of Vanadium in Basic Oxygen Furnace Slags

Renno, A.; Möckel, R.; Frenzel, M.; Ebert, D.; Bachmann, K.; Krause, J.; Gutzmer, J.

With the increasing demand for metalliferous and mineral raw materials and the consequent depletion of the global natural resource base, the possible utilization of secondary raw material sources is receiving more and more attention. In the present study, we present results from a detailed vanadium deportment study of three basic oxygen furnace slag (BOS) samples known to containing elevated bulk concentrations of vanadium. Complementary analytical methods that were used to quantify the abundance and composition of V-containing phases include SEM-based automated mineralogy, X-ray fluorescence analysis, and X-ray powder diffraction as well as electron probe microanalysis. The vanadium deportment was quantified using Monte-Carlo simulations of the data obtained from automated mineralogy and electron microprobe analysis. The total V concentrations identified by XRF are between 1.7 and 2.2 wt.% V. The most important hosts of vanadium are larnite-, brownmillerite- and portlandite-solid solutions. In two samples Ca carbonates also significantly contribute to the V deportment, while wuestite, lime, and native iron do not contribute significantly to the vanadium deportment. A thorough consistency
check identifies considerable uncertainties in the density of the V-bearing phases as the most likely reason to explain
remaining discrepancies between measured and calculated V values

Keywords: Steel slag; Basic oxygen furnace slag; Vanadium-bearing slag; Vanadium; Vanadium deportment

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Permalink: https://www.hzdr.de/publications/Publ-37633
Publ.-Id: 37633


Photonic model for airborne microorganisms inactivation by UV radiation

Cavagnola, M. A.; Eßlinger, F.; Hampel, U.; Ebert, G.; Lecrivain, G.

Since the coming of the COVID-19 pandemic in 2019, virus spreading in confined spaces has been in the spotlight. Ultraviolet germicidal irradiation has proven to be an efficient method of rendering airborne microorganisms inactive. In the present study, a novel model for airborne virus/bacteria inactivation using UV-light is presented. A particle-to-particle photonic approach that takes into account each of the interactions between the microorganism particles and UV-light photons is obtained. The main advantage of the presented model is its faithfulness to the physical reality of the inactivation process, i.e. that the ultraviolet inactivation effect is a stochastic process not a deterministic one. This characteristic allows the model to track and calculate the inactivation success for each of the single particles conforming a particle cloud. The model is validated against published data of inactivation of aerolized Escherichia coli bacteria in a UV-reactor and will be validated experimentally using a seasonal coronavirus in a Potential Aerosol Mass Oxidation Flow Reactor at the Helmholtz-Zentrum in Munich.

  • Poster
    European Aerosol Conference, 04.-08.09.2023, Malaga, Spanien

Permalink: https://www.hzdr.de/publications/Publ-37632
Publ.-Id: 37632


PSMA: Aktuelle und zukünftige Entwicklungen

Kiß, O.

PSMA: Aktuelle und zukünftige Entwicklungen

  • Invited lecture (Conferences)
    29. Jahrestagung der Berlin-Brandenburgischen Gesellschaft für Nuklearmedizin, 10.-11.11.2023, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37631
Publ.-Id: 37631


RIVERSAND: A new tool for efficient computation of catchmentwide erosion rates

Stübner, K.; Balco, G.; Schmeißer, N.

In-situ cosmogenic 10Be (and 26Al) concentrations in alluvial sediments provide a spatially averaged signal of the erosion rate of the catchment area. Catchmentwide erosion rates reflect the production rate of the entire basin, and their calculation requires knowledge of the complete production rate model. Available calculators determine production rates on a pixel-based approach and achieve computational efficiency by relying on a scaling method that ignores geomagnetic field strength variations. Here we introduce a new python-based tool that determines erosion rates based on the hypsometry of the catchment. The method relies on the fact that production rates are much more sensitive to changes in elevation than latitude. Our tool has two main advantages: (1) computation time is short (<30 seconds) and independent of the scaling method; there is no need to neglect magnetic field variations, and (2) because production rate scaling is performed by a widely used online calculator, the results are fully comparable to exposure ages or point-based erosion rates determined with the same calculator; future updates to production rate scaling are immediately effective for catchmentwide erosion rate calculation. We demonstrate in two case studies that (1) for similar scaling methods, our calculator reproduces pixel-based results within a few percent, and (2) erosion rates determined with different scaling methods may differ by >20%, differences can vary systematically with erosion rate, and using a time-constant scaling method may result in a bias in the interpretation of catchmentwide erosion rates.

Keywords: AMS; AMS dating; denudation; erosion; landscape evolution

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Permalink: https://www.hzdr.de/publications/Publ-37630
Publ.-Id: 37630


Photonic model for airborne microorganisms inactivation by UV radiation

Cavagnola, M. A.; Eßlinger, F.; Hampel, U.; Ebert, G.; Lecrivain, G.

Since the coming of the COVID-19 pandemic in 2019, virus spreading in confined spaces has been in the spotlight. Ultraviolet germicidal irradiation (UVGI) has proven to be an efficient method of rendering airborne microorganisms inactive. In the present study, a novel model for airborne microorganisms inactivation using UV-light is presented. A particle-to-particle photonic approach that takes into account each of the interactions between microorganisms and UV-light photons is obtained. The main advantage of the presented model is its faithfulness to to the physical reality of the inactivation process, i.e. that ultraviolet inactivation is a stochastic process not a deterministic one. This characteristic allows the model to track and calculate the inactivation success for each of the single particles conforming a particle cloud. The model is validated against experimental data of SARS Corona-virus 2 inactivation in a UV-reactor and against published data of of aerolized Escherichia coli and Pseudomonas aeruginosa bacteria inactivation.

  • Poster
    CORAERO spring PhD School, 09.05.2023, DLR Göttingen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37629
Publ.-Id: 37629


Three Pleistocene glacial advances and a warm episode during MIS-3: Towards a more complete glacial history of the Pamir Mountains

Stübner, K.; Gadoev, M.; Rugel, G.; Lachner, J.; Bookhagen, B.

Understanding the spatial and temporal variations of Pleistocene glaciations is key to understanding present-day climate-driven glacier changes. Glacial chronologies of high-mountain Asia, which are mostly based on cosmogenic 10Be exposure dating of moraine boulders, remain scarce and often inaccurate due to geologically induced age scatter. We present 53 new 10Be exposure ages from rockslides, glacial sediment deposits and glacial erosion surfaces in the southwestern Pamir. In conjunction with previously published 10Be data, we constrain the timing and extent of three major glacial stages in the Pamir. During the Middle Pleistocene, a continuous ice sheet covered most of the Pamir. This stage is older than 200 ka and may have occurred during Marine Isotope Stages (MIS) 8, 10, or 12. The deep valleys of the western Pamir, which constrast with the east Pamir plateau, are partly attributed to Middle Pleistocene glacial erosion. Successively less extensive glacial advances occurred during MIS-4/5 (between 60 and 100 ka ago) and during MIS-2 (at 18-22 ka). The last glacial maximum was synchronous in most of the Pamir, except for prolonged glaciation of the Muztagh Ata ice cap until 14 ka ago. Similar to today, Late Pleistocene glaciers were precipitation-limited with moisture supplied mostly by westerly winds. An episode of increased mass wasting (e.g. Zuvor rockslide: 34 ± 1 ka) and glacier surging correlates with a peak in δ 18 O values in the Guliya ice core and is attributed to a warmer climate.

Keywords: Central Asia; glacial chronology; cosmogenic nuclide; exposure age; moraine; rockslide

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Permalink: https://www.hzdr.de/publications/Publ-37628
Publ.-Id: 37628


Influence of oxidic and metallic interfaces on the magnetic damping of Permalloy thin films

Ney, V.; Salikhov, R.; Lenz, K.; Hellwig, O.; Lindner, J.; Ney, A.

Magnetic damping within Permalloy (Py) thin films is studied via temperature- and frequencydependent ferromagnetic resonance (FMR) experiments. While the Py thickness is kept constant at 20 nm, the environment at the film interfaces was systematically varied by fabricating a set of Py thin films grown on widely used substrates and capped with common layers, which are assumed to be suitable to prevent oxidation. The resulting frequency- and temperature-dependence of the FMR linewidth significantly deviates from the expected Gilbert-like behavior and especially for oxidic interfaces unwanted non-Gilbert-like contributions to the magnetic damping appear, in particular at low temperatures. It turns out that Py sandwiched in-between metallic capping and buffer layers
of Al exhibits the smallest magnetic damping of purely Gilbert-like nature.

Keywords: Thin films; ferromagnetism; ferromagnetic resonance; anisotropy; linewidth

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  • Secondary publication expected from 11.12.2024

Permalink: https://www.hzdr.de/publications/Publ-37626
Publ.-Id: 37626


Terahertz Twistoptics–Engineering Canalized Phonon Polaritons

Obst, M.; Nörenberg, T.; Álvarez-Pérez, G.; de Oliveira, T.; Taboada-Gutiérrez, J.; Feres, F. H.; Kaps, F. G.; Hatem, O.; Luferau, A.; Nikitin, A. Y.; Klopf, J. M.; Alonso-González, P.; Kehr, S. C.; Eng, L. M.

The terahertz (THz) frequency range is key to studying collective excitations in many crystals and organic molecules. However, due to the large wavelength of THz radiation, the local probing of these excitations in smaller crystalline structures or few-molecule arrangements requires sophisticated methods to confine THz light down to the nanometer length scale, as well as to manipulate such a confined radiation. For this purpose, in recent years, taking advantage of hyperbolic phonon polaritons (HPhPs) in highly anisotropic van der Waals (vdW) materials has emerged as a promising approach, offering a multitude of manipulation options, such as control over the wavefront shape and propagation direction. Here, we demonstrate the THz application of twist-angle-induced HPhP manipulation, designing the propagation of confined THz radiation between 8.39 and 8.98 THz in the vdW material α-molybdenum trioxide (α-MoO3), hence extending twistoptics to this intriguing frequency range. Our images, recorded by near-field optical microscopy, show the frequency- and twist-angle-dependent changes between hyperbolic and elliptic polariton propagation, revealing a polaritonic transition at THz frequencies. As a result, we are able to allocate canalization (highly collimated propagation) of confined THz radiation by carefully adjusting these two parameters, i.e. frequency and twist angle. Specifically, we report polariton canalization in α-MoO3 at 8.67 THz for a twist angle of 50°. Our results demonstrate the precise control and manipulation of confined collective excitations at THz frequencies, particularly offering possibilities for nanophotonic applications.

Keywords: s-SNOM; FEL; FELBE; THz; IR; nearfield spectroscopy; phonon polariton; twisted bilayer

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Permalink: https://www.hzdr.de/publications/Publ-37625
Publ.-Id: 37625


Data publication: Estimation of the yield strength from small punch testing

Altstadt, E.

Finite element simulations of the small punch test are performed.Generic elastic-plastic material properties are used. A systematic variation of the yield stress, ultimate tensile stress and uniform elongation is performed to investigate the effects of these parameters of the uniaxial stress-strain curve on the characteristics of small punch force-deflection curves. Moreover, the effect of sample thickness is studied. It is shown that the currently used elastic-plastic transition force – obtained by bi-linear fitting – does not only depend on the yield strength but also on the work hardening behavior of the material. An alternative definition of the elastic-plastic transition force is proposed, which significantly less depends on the work hardening of the material. The approach is based on the deviation of the force-deflection curve from the analytical elastic slope derived by Reissner's plate theory. The new definition of the transition force leads to significantly reduced dependence of the correlation factor on the geometry of the small punch set-up.

Keywords: small punch test; yield strength; empirical correlation; finite element simulation; plate theory

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Permalink: https://www.hzdr.de/publications/Publ-37624
Publ.-Id: 37624


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