Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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35836 Publications

Solution synthesis and dielectric properties of alumina thin films: understanding the role of the organic additive in film formation

Hoffmann, R. C.; Liedke, M. O.; Butterling, M.; Wagner, A.; Trouilletc, V.; Schneider, J. J.

Alumina thin films are synthesized by combustion synthesis of mixtures of aluminium nitrate (ALN) and methylcarbazate (MCZ). The interdependence of the ratio of oxidizer and reducing agent on composition, microstructure and electronic properties of the resulting oxide layers is investigated. The dielectric and insulating behaviour is improved by addition of different amounts of MCZ (MCZ : ALN = 0.67 or 2.5). In this way films (thickness ∼140 nm) with a dielectric constant κ of 9.7 and a dielectric loss tan δ below 0.015 can be achieved. Medium concentrations of MCZ (MCZ : ALN = 1.0 or 1.5) lead to films with lower performance, though. Our studies indicate two opposing effects of the organic additive. Removal of organic residues during film formation as combustion gases is potentially detrimental. Larger amounts of MCZ, however, cause condensation reactions in the precusor mixture, which improve the microstructure. The porosity of the films can be sucessfully analyzed by positron annihilation liftetime studies. In this way the impact of the organic ligand sphere on the resulting microstructure can be quantified. Samples prepared from ALN alone exhibit mesopores and also larger micropores. In contrast, the formation of mesopores can be inhibited by addition of MCZ.

Keywords: alumina; thin films; Al2O3; positron annihilation spectroscopy; combustion synthesis; dielectrics; insulator

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  • Secondary publication expected from 07.06.2022

Permalink: https://www.hzdr.de/publications/Publ-32731
Publ.-Id: 32731


Exceptional field dependence of antiferromagnetic magnons in LiFePO4

Werner, J.; Neef, C.; Koo, C.; Ponomaryov, O.; Zvyagin, S.; Klingeler, R.

Low-energy magnon excitations in magnetoelectric LiFePO4 have been investigated by high-frequency–highfield electron spin resonance spectroscopy inmagnetic fields up to B = 58 T and frequencies up to f = 745 GHz. For magnetic fields applied along the easy magnetic axis, the excitation gap softens and vanishes at the spin-flop field of BSF = 32 T before hardening again at higher fields. In addition, for B ≲ BSF we observe a resonance mode assigned to excitations due to Dzyaloshinskii-Moriya (DM) interactions, thereby evidencing a sizable DM interaction of ≈150 μeV in LiFePO4. Both the magnetization and the excitations up to high magnetic fields are described in terms of a mean-field theory model which extends recent zero-field inelastic neutron scattering results. Our results imply that magnetic interactions as well as magnetic anisotropy have a sizable quadratic field dependence which we attribute to significant magnetostriction.

Permalink: https://www.hzdr.de/publications/Publ-32730
Publ.-Id: 32730


Magnetohydrodynamic effects in liquid metal batteries

Weber, N.; Benard, S.; Horstmann, G. M.; Klopper, T. S.; Landgraf, S.; Nimtz, M.; Personnettaz, P.; Stefani, F.; Weier, T.

Liquid metal batteries (LMBs) are a new technology for grid-scale energy storage. They consist of all liquid cells that operate
with liquid metals as electrodes and molten salts as electrolytes. The
liquids separate into three stably stratified layers by virtue of
density and mutual immiscibility (see the two upper left inserts in
Fig.~\ref{fig}a). This conceptually very simple and self-assembling
structure has the unique advantage to allow for an easy scale-up at
the cell level: single-cell cross sections can potentially reach
several square-meters. Such cell sizes enable highly favourable and
otherwise unattainable ratios of active to construction material
because of the cubic scaling (volume) of the former and the quadratic
scaling (surface) of the latter.

The talk will start with a general introduction to LMBs and then focus
on the fluid mechanics in these devices. Electric currents, magnetic fields, and heat
and mass transfer are tightly coupled with the cells'
electrochemistry. First a number of fluid dynamic instabilities will
be discussed in relation to operational safety. The remainder of the
talk will deal with transport phenomena in the positive
electrode. While transport in most modern battery systems is typically
dominated by diffusion and migration in micrometer-scale liquid layers
and solids, convection - with exception of the aforementioned
redox-flow batteries - rarely plays a role. This is in stark contrast
to LMBs were mediated by the fully liquid interior fluid flow can be
driven by various mechanisms. The influence of solutal convection on
the cycling behavior of a cell will be
demonstrated. Electromagnetically induced convection can be used to
improve mixing thereby mitigating diffusion
overpotentials.

Keywords: Liquid metal batteries; wave coupling; mass transport; energy storage; Magnetohydrodynamics

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    Electromagnetic processing of materials 2021 - Summer course, 09.-11.06.2021, Riga, Lettland

Permalink: https://www.hzdr.de/publications/Publ-32729
Publ.-Id: 32729


Ultrasound measurement technique for the single-turn-coil magnets

Nomura, T.; Hauspurg, A.; Gorbunov, D.; Miyata, A.; Schulze, E.; Zvyagin, S.; Tsurkan, V.; Matsuda, Y. H.; Kohama, Y.; Zherlitsyn, S.

Ultrasound is a powerful means to study numerous phenomena of condensed-matter physics as acoustic waves couple strongly to structural, magnetic, orbital, and charge degrees of freedom. In this paper, we present such a technique combined with single-turn coils (STCs) that generate magnetic fields beyond 100 T with the typical pulse duration of 6 μs. As a benchmark of this technique, the ultrasound results for MnCr2S4, Cu6[Si6O18]⋅6H2O, and liquid oxygen are shown. The resolution for the relative sound-velocity change in the STC is estimated as Δv/v ∼ 10−3, which is sufficient to study various field-induced phase transitions and critical phenomena.

Permalink: https://www.hzdr.de/publications/Publ-32728
Publ.-Id: 32728


Raw data, magnetization measurements for paper Room temperature ferromagnetism in Sb doped ZnO

Xu, C.; Zhou, S.

Raw data, magnetization measurements for samples involved in paper Room temperature ferromagnetism in Sb doped ZnO

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-06-08
    DOI: 10.14278/rodare.1000
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-32727
Publ.-Id: 32727


Room temperature ferromagnetism in Sb doped ZnO

Luo, C.-Q.; Zhu, S.-C.; Xu, C.; Zhou, S.; Lame, C.-H.; Ling, F. C.-C.

Using first-principle calculations, the magnetic properties of the monovacancies and the Sb-related defects including VZn, VO, SbZn, SbO, SbZn-VZn and SbZn-2VZn are studied. It is found that the isolated VZn with the charge state of 0 and −1 can contribute to ferromagnetism in ZnO material. The substitution of Sb on O sites (SbO0) also results in magnetic property. Moreover, the SbZn-2VZn complex is another defect having non-zero magnetic moment and energetically favors for the ferromagnetic state. The resultant density of states (DOS) and spin density distribution clearly show that the ferromagnetic interaction is majorly due to the O-p Zn-d and Sb-p states. To check this calculation, Sb-doped ZnO samples were grown by pulsed laser deposition with different Sb composition under P(O2) = 1.3 Pa. SQUID study showed that all of these samples are ferromagnetic at room temperature. The variation of the saturation magnetization against the Sb composition is discussed.

Related publications

Downloads:

  • Secondary publication expected from 09.03.2022

Permalink: https://www.hzdr.de/publications/Publ-32726
Publ.-Id: 32726


Real time flow control during continuous casting with Contactless Inductive Flow Tomography

Glavinic, I.; Stefani, F.; Eckert, S.; Wondrak, T.

Lack of appropriate flow measurement techniques for liquid steel during continuous casting limits the application of control strategies that could improve the quality of the end product. Contactless Inductive Flow Tomography (CIFT) is a promising measurement technique that can provide information about the flow structure in the mould to a real time controller. On this basis, electromagnetic actuators can be used to react on undesired flow conditions in the mould. However, because of their nature, these actuators pose a significant challenge for inductive measurement methods. In this work we describe the influence of an electromagnetic brake on CIFT in a laboratory environment. We also show how this influence can be fully compensated, which facilitates the viability of CIFT as a key ingredient of real time control of continuous casting.

Keywords: Contactless inductive flow tomography; Continuous casting; Electromagnetic brake

  • Open Access Logo Contribution to proceedings
    Electromagnetic processing of materials 2021, 13.-17.06.2021, Riga, Latvia
  • Lecture (Conference) (Online presentation)
    Electromagnetic processing of materials 2021, 16.06.2021, Riga, Latvia

Permalink: https://www.hzdr.de/publications/Publ-32723
Publ.-Id: 32723


Final Results of the Prospective Biomarker Trial PETra: [11C]-MET-Accumulation in Postoperative PET/MRI Predicts Outcome after Radiochemotherapy in Glioblastoma

Seidlitz, A.; Beuthien-Baumann, B.; Löck, S.; Jentsch, C.; Platzek, I.; Zöphel, K.; Linge, A.; Kotzerke, J.; Petr, J.; van den Hoff, J.; Steinbach, J.; Krex, D.; Schmitz-Schackert, G.; Falk, M.; Baumann, M.; Krause, M.

Purpose: This prospective trial investigates the association of time to recurrence (TTR) in glioblastoma with [11C]methionine (MET) tracer uptake before postoperative radiochemotherapy (RCT) aiming to guide radiotherapy boost regions.

Experimental Design: Between 2013 and 2016, 102 patients with glioblastoma were recruited. RCT was performed with concurrent and adjuvant temozolomide to a total dose of 60 Gy. Tumor residues in postresection PET and MRI were together defined as gross tumor volumes for radiotherapy treatment planning. [11C]methionine (MET)-PET/MRI was performed before RCT and at each follow-up.

Results: The primary hypothesis of a longer TTR for patients without increased tracer accumulation in postoperative MET-PET was confirmed in 89 patients. With 18.9 months (95% confidence interval, 9.3–28.5 months), median TTR was significantly (P < 0.001) longer for patients without (n = 29, 32.6%) as compared with 6.3 months (3.6–8.9) for patients with MET accumulation (n = 60, 67.4%) in pre-RCT PET. Although MRI often did not detect all PET-positive regions, an unfavorable impact of residual tumor in postsurgical MRI (n = 38, 42.7%) on TTR was observed [4.6 (4.2–5.1) vs. 15.5 months (6.0–24.9), P < 0.001]. Significant multivariable predictors for TTR were MRI positivity, PET-positive volume, and O6-methylguanine DNA methyltransferase (MGMT) hypermethylation.

Conclusions: Postsurgical amino acid PET has prognostic value for TTR after RCT in glioblastoma. Because of the added value of the metabolic beyond the pure structural information, it should complement MRI in radiotherapy planning if available with reasonable effort, at least in the context of maximal therapy. Furthermore, the spatial correlation of regions of recurrence with PET-positive volumes could provide a bioimaging basis for further trials, for example, testing local radiation dose escalation.

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  • Secondary publication expected from 31.03.2022

Permalink: https://www.hzdr.de/publications/Publ-32718
Publ.-Id: 32718


Exploring Data Version Control for machine learning pipelines in research

Sultova, N.

Exploration of Data Version Control as framework for managing machine learning workflows for HelmholtzAI.
The content consists of blogposts and additional code to follow along the tutorials-part.

Keywords: machine learning version control pipelines

Permalink: https://www.hzdr.de/publications/Publ-32717
Publ.-Id: 32717


Origin of the quasi-quantized Hall effect in ZrTe5

Galeski, S.; Ehmcke, T.; Wawrzyńczak, R.; Lozano, P. M.; Cho, K.; Sharma, A.; Das, S.; Küster, F.; Sessi, P.; Brando, M.; Küchler, R.; Markou, A.; König, M.; Swekis, P.; Felser, C.; Sassa, Y.; Li, Q.; Gu, G.; Zimmermann, M. V.; Ivashko, O.; Gorbunov, D.; Zherlitsyn, S.; Förster, T.; Parkin, S. S. P.; Wosnitza, J.; Meng, T.; Gooth, J.

The quantum Hall effect (QHE) is traditionally considered to be a purely two-dimensional (2D) phenomenon. Recently, however, a three-dimensional (3D) version of the QHE was reported in the Dirac semimetal ZrTe5. It was proposed to arise from a magnetic-field-driven Fermi surface instability, transforming the original 3D electron system into a stack of 2D sheets. Here, we report thermodynamic, spectroscopic, thermoelectric and charge transport measurements on such ZrTe5 samples. The measured properties: magnetization, ultrasound propagation, scanning tunneling spectroscopy, and Raman spectroscopy, show no signatures of a Fermi surface instability, consistent with in-field single crystal X-ray diffraction. Instead, a direct comparison of the experimental data with linear response calculations based on an effective 3D Dirac Hamiltonian suggests that the quasi-quantization of the observed Hall response emerges from the interplay of the intrinsic properties of the ZrTe5 electronic structure and its Dirac-type semi-metallic character.

Permalink: https://www.hzdr.de/publications/Publ-32716
Publ.-Id: 32716


Topological magnetic order and superconductivity in EuRbFe4As4

Hemmida, M.; Winterhalter-Stocker, N.; Ehlers, D.; Krug Von Nidda, H.-A.; Yao, M.; Bannies, J.; Rienks, E. D. L.; Kurleto, R.; Felser, C.; Büchner, B.; Fink, J.; Gorol, S.; Förster, T.; Arsenijevic, S.; Fritsch, V.; Gegenwart, P.

We study single crystals of the magnetic superconductor EuRbFe4As4 by magnetization, electron spin resonance (ESR), angle-resolved photoemission spectroscopy, and electrical resistance in pulsed magnetic fields up to 63 T. The superconducting state below 36.5 K is almost isotropic and is only weakly affected by the development of Eu2+ magnetic order at 15 K. On the other hand, for the external magnetic field applied along the c axis the temperature dependence of the ESR linewidth reveals a Berezinskii-Kosterlitz-Thouless topological transition below 15 K. This indicates that Eu2+ planes are a good realization of a two-dimensional XY magnet, which reflects the decoupling of the Eu2+ magnetic moments from superconducting FeAs layers.

Permalink: https://www.hzdr.de/publications/Publ-32715
Publ.-Id: 32715


Automated objective optimization of iterative image reconstruction protocols

Nikulin, P.; Maus, J.; Hofheinz, F.; van den Hoff, J.

Goal
The image quality achieved in iterative PET image reconstruction is influenced by several internal and user-settable parameters (number of iterations and subsets, PSF model, etc.). Typically, there are more than 3 user-settable parameters involved, interacting in a non-intuitive way. Reasonable settings typically are obtained interactively by try-and-error which is highly subjective. This proof-of-concept work proposes a method for automated reconstruction parameters optimization for a given, preselected image quality metric.

Methods
In out approach, we reconstruct images of cylindrical phantom with six "hot" sphere inserts simulating lesions of different sizes and target-to-background activity concentration ratios (20:1, 10:1, 5:1). 4 parameters of our in-house reconstruction tool THOR [1] were varied during optimization: no. of iterations and subsets, tube of response (ToR) radius, Gaussian post filter FWHM. As image quality metric we chose the weighted sum of standard deviation of contrast recovery coefficients of all 6 inserts (as a surrogate for image resolution), the image noise, and Gibbs artifacts. This metric is minimized with Bayesian optimization method using Gaussian process as a surrogate function. The reconstruction parameters resulting in the minimum metric value were chosen.

Results
The optimization process lasted for 50 iterations. The resulting reconstruction parameters were: no. of iterations/subsets=2/21, ToR radius=2.95mm, Gaussian filter FWHM=4.0mm. The resulting images show [4.7-5.8]mm resolution and 14% noise level. Gibbs artifacts level was found to be below 3.5%.

Conclusion
Our framework for reconstruction protocol optimization is capable of deriving reasonable reconstruction parameters in a fully automated manner. The presented approach might also be used to improve and objectify the comparison of different image reconstruction algorithms.

Literature

[1] A. Lougovski, et al., Physics in Medicine and Biology, vol.59(3), p.561, 2014

Keywords: PET; Iterative image reconstruction; THOR; MLEM; Bayesian optimization

  • Lecture (Conference) (Online presentation)
    NuklearMedizin 2021 – hybrid, 14.-17.04.2021, Online, Online
  • Contribution to proceedings
    NuklearMedizin 2021 – hybrid, 14.-17.04.2021, Online, Online
    Nuklearmedizin 2021; 60(02): 151, eRef: Thieme Publishing Group
    DOI: 10.1055/s-0041-1726740

Permalink: https://www.hzdr.de/publications/Publ-32711
Publ.-Id: 32711


Simultaneous Ligand and Cation Exchange of Colloidal CdSe Nanoplatelets toward PbSe Nanoplatelets for Application in Photodetectors

Galle, T.; Spittel, D.; Weiß, N.; Shamraienko, V.; Decker, H.; Georgi, M.; Hübner, R.; Metzkow, N.; Steinbach, C.; Schwarz, D.; Lesnyak, V.; Eychmüller, A.

Cation exchange emerged as a versatile tool to obtain a variety of nanocrystals not yet available via a direct synthesis. Reduced reaction times and moderate temperatures make the method compatible with anisotropic nanoplatelets (NPLs). However, the subtle thermodynamic and kinetic factors governing the exchange require careful control over the reaction parameters to prevent unwanted restructuring. Here, we capitalize on the research success of CdSe NPLs by transforming them into PbSe NPLs suitable for optoelectronic applications. In a two-phase mixture of hexane/Nmethylformamide, the oleate-capped CdSe NPLs simultaneously undergo a ligand exchange to NH4I and a cation exchange reaction to PbSe. Their morphology and crystal structure are well-preserved as evidenced by electron microscopy and powder X-ray diffraction. We demonstrate the successful ligand exchange and associated electronic coupling of individual NPLs by fabricating a simple photodetector via spray-coating on a commercial substrate. Its optoelectronic characterization reveals a fast light response at low operational voltages.

Permalink: https://www.hzdr.de/publications/Publ-32705
Publ.-Id: 32705


Magnetite surfaces for radionuclide retention using DFT+U

Katheras, A.; Karalis, K.; Krack, M.; Scheinost, A.; Churakov, S. V.

In many countries, spent nuclear fuel and high-level radioactive waste from operation of nuclear power plants will be stored in deep geological repositories. Thick steel casks are used to prevent the release of radionuclides into the environment. Steel is known to slowly corrode under repository conditions forming mixed iron oxides e.g. magnetite (Fe3O4). It is expected that after a long corrosion period of several ten thousand years, the steel casks may breach and long-lived radionuclides (e.g. plutonium (Pu), technetium (Tc)) may get in contact with the steel oxidation products. Such interaction can result in the formation of surface complexes or incorporation of the radionuclides into the crustal structures. The pre-dominance of one or another mechanism will strongly affect the retention and transport of long-lived hazardous radionuclides. The mechanism of these reactions, especially the structural relationships at the solid-liquid interface and adsorption kinetic, are poorly understood at the atomistic scale. This project further investigates the redox sensitive uptake of Tc and Pu at the surface of magnetite under incorporation of these elements into the magnetite structure combining atomistic simulations and X-ray absorption spectroscopy1,2.
The necessary preparatory step in this study is the identification of dominant low index surfaces on nano-magnetite particles and their termination at the relevant conditions. The atomistic simulations based on the Kohn-Sham density functional theory (DFT) are performed using the open source CP2K code. For highly correlated chemical elements such as iron (Fe), a correction due to the highly localized 3d electrons is necessary and can be achieved by utilizing the DFT+U method. Initially, the Hubbard U parameter has been determined similar to earlier investigations3 by comparing the experimental cell constants and the band gap. The preferential magnetite orientation plane (111) with six different surface terminations are examined as function of oxygen or water fugacity.

1 R. Kirsch, D. Fellhauer, M. Altmaier, V. Neck, A. Rossberg, T. Fanghänel, L. Charlet and A. C. Scheinost, Environmental Science & Technology, 2011, 45, 7267–7274.
2 E. Yalç𝚤ntas, A. C. Scheinost, X. Gaona and M. Altmaier, Dalton Transactions, 2016, 45, 17874–17885.
3 A. Kéri, R. Dähn, M. Krack and S. V. Churakov, Environmental Science & Technology, 2017, 51, 10585–10594.

Keywords: Magnetite; DFT; Nuclear waste; Sorption; Structural incorporation

  • Poster (Online presentation)
    CECAM workshop on “Multi-approach modeling of alloy nanoparticles: from non-equilibrium synthesis to structural and functional properties", 07.-09.07.2021, Lausanne, Switzerland

Permalink: https://www.hzdr.de/publications/Publ-32701
Publ.-Id: 32701


The contribution of hydrodynamic processes to calcite dissolution rates and rate spectra

Agrawal, P.; Bollermann, Till; Raoof, A.; Iliev, O.; Fischer, C.; Wolthers, M.

Recent measurements on the dissolution rate of nano- and micron-scale rough calcite surfaces have shown lateral variations in dissolution rate, which can be quantified using rate spectra. This study uses numerical simulations to investigates the hydrodynamic processes during such experiments to explore whether hydrodynamic effects can explain the observed dissolution rate spectra. For this purpose, we simulated the dissolution processes of nano- and micron-scale rough calcite surfaces in COMSOL Multiphysics. We imposed surface topographies and local reaction rates measured using Vertical Scanning Interferometry (VSI), and implemented the same flow rate (i.e., 6 × 10−8 m3 s−1), solution chemistry (pH 8.8, alkalinity 4.4 meq/kg-H2O and pCO2 10−3.48 bar) and flow-cell geometry as those used in the experiment. We have compared the simulated rate spectra against the experimentally measured values at a calcite surface having the same surface topography and reactive-flow conditions.

Simulations using a single dissolution rate for the rough calcite surface did not produce similarly wide dissolution rate spectra like those observed experimentally. Our results have shown that only by explicitly incorporating the rate spectra in the model the simulated and the measured rate spectra would match. Sensitivity analyses by varying chemical composition and flow velocity were performed to examine the effects of these parameters on the calculated rate spectra. This study concludes that for the reactive-flow regimes where dissolution rate spectra are observed experimentally, the chemical heterogeneity, topography of the crystal surface and the resulting heterogeneity in the free energy landscape at the surface play a major role in controlling the dissolution rate spectra. With the injection of more acidic (pH 2) solutions at higher velocities (i.e., 0.04 m s−1), we observed an increase in the hydrodynamics-induced rate variability at microscopically rough surfaces

Keywords: Calcite dissolution; Pore-scale reactive transport model; Microscopic surface experiments; Surface roughness; Hydrodynamic effects; Dissolution rate spectra

Permalink: https://www.hzdr.de/publications/Publ-32700
Publ.-Id: 32700


Enhancing Ferromagnetism and Tuning Electronic Properties of CrI3Monolayers by Adsorption of Transition-Metal Atoms

Yang, Q.; Hu, X.; Shen, X.; Krasheninnikov, A.; Chen, Z.; Sun, L.

Among first experimentally discovered two-dimensional (2D) ferromagnetic materials, chromium triiodide (CrI3) monolayers have attracted particular attention due to their potential applications in electronics and spintronics. However, the Curie temperature Tc of the CrI3 monolayer is below room temperature, which greatly limits practical development of the devices. Herein, using density functional theory calculation, we explore how the electronic and magnetic properties of CrI3 monolayers change upon adsorption of 3d transition-metal (TM) atoms (from Sc to Zn). Our results indicate that the electronic properties of the TM-CrI3 system can be tuned from semiconductor to metal/half-metal/spin gapless semiconductor depending on the choice of the adsorbed TM atoms. Moreover, the adsorption can improve the ferromagnetic stability of CrI3 monolayers by increasing both magnetic moments and Tc. Notably, Tc of CrI3 with Sc and V adatoms can be increased by nearly a factor of 3. We suggest postsynthesis doping of 2D CrI3 by deposition of TM atoms as a new route toward potential applications of TM-CrI3 systems in nanoelectronic and spintronic devices.

Keywords: 2D materials; adsorption; magnetic properteis

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  • Secondary publication expected from 27.04.2022

Permalink: https://www.hzdr.de/publications/Publ-32699
Publ.-Id: 32699


Defect Agglomeration and Electron Beam-Induced Local Phase Transformations in Single-Layer MoTe₂

Köster, J.; Ghorbani Asl, M.; Lehnert, T.; Komsa, H.-P.; Kretschmer, S.; Krasheninnikov, A.; Kaiser, U.

Atom migrations in single-layer 1H-MoTe₂ are studied with Cc/Cs-corrected high-resolution transmission electron microscopy (TEM) at an electron energy of 40 keV using the electron beam simultaneously for material modification and imaging. After creating tellurium vacancies and vacancy lines, we observe their migration pathways across the lattice. Furthermore, we analyze phase transformations from the 1H- to the 1T’-phase associated with the strain-induced due to the formation of Te vacancy lines. Combining the experimental data with the results of first-principles calculations, we explain energetics and driving forces of point and line defect migration and the phase transformations due to an interplay of electron-beam-induced energy input, atom ejection, and strain spread. Our results enhance the understanding of defect dynamics in 2D transition metal dichalcogenides, which should facilitate tailoring their local optical and electronic properties.

Keywords: two-dimensional materials; transition metal dichalcogenides; transmission electron microscopy; defects; first-principles calculations

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  • Secondary publication expected from 13.06.2022

Permalink: https://www.hzdr.de/publications/Publ-32698
Publ.-Id: 32698


Dichotomy in temporal and thermal spin correlations observed in the breathing pyrochlore LiGa1−xInxCr4O8

Lee, S.; Do, S.-H.; Lee, W.; Choi, Y. S.; van Tol, J.; Reyes, A. P.; Gorbunov, D.; Chen, W.-T.; Choi, K.-Y.

A breathing pyrochlore system is predicted to host a variety of quantum spin liquids. Despite tremendous experimental and theoretical efforts, such sought-after states remain elusive as perturbation terms and lattice distortions lead to magnetic order. Here, we utilize bond alternation and disorder to tune a magnetic ground state in the Cr-based breathing pyrochlore LiGa1−xInxCr4O8. By combining thermodynamic and magnetic resonance techniques, we provide experimental signatures of a spin-liquid-like state in x = 0.8, namely, a nearly T2-dependent magnetic specific heat and persistent spin dynamics by muon spin relaxation (μSR). Moreover, Li NMR, ZF-μSR, and ESR unveil the temporal and thermal dichotomy of spin correlations: a tetramer singlet on a slow time scale vs. a spin-liquid-like state on a fast time scale. Our results showcase that a bond disorder in the breathing pyrochlore offers a promising route to disclose exotic magnetic phases.

Permalink: https://www.hzdr.de/publications/Publ-32696
Publ.-Id: 32696


Magnetic properties of a quantum spin ladder in proximity to the isotropic limit

Zvyagin, S.; Ponomaryov, O.; Ozerov, M.; Schulze, E.; Scurschii, I.; Beyer, R.; Reimann, T.; Zviagina, L.; Green, E. L.; Wosnitza, J.; Sheikin, I.; Bouillot, P.; Giamarchi, T.; Wikara, J. L.; Turnbull, M. M.; Landee, C. P.

We report on the synthesis, crystal structure, magnetic, thermodynamic, and electron-spin-resonance properties of the coordination complex [Cu2(pz)3(4-HOpy)4](ClO)4 (pz = pyrazine; 4-HOpy = 4-hydroxypyridine). This material is identified as a spin-1/2 Heisenberg ladder system with exchange-coupling parameters Jrung/kB = 12.1(1) K and Jleg/kB = 10.5(3) K [Jrung/Jleg = 1.15(4)]. For single crystals our measurements revealed two critical fields, μ0Hc1 = 4.63(5) T and μ0Hc2 = 22.78(5) T (for H II a*), separating the gapped spin-liquid, gapless Tomonaga-Luttinger-liquid, and fully spin-polarized phase. No signature of a field-induced transition into a magnetically ordered phase was found at temperatures down to 450 mK. The material bridges an important gap by providing an excellent physical realization of an almost isotropic spin-1/2 strong-rung Heisenberg ladder system with modest exchange-coupling energy and critical-field scales.

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Permalink: https://www.hzdr.de/publications/Publ-32694
Publ.-Id: 32694


Distinct field-induced ferroquadrupolar states for two different magnetic-field directions in DyNiAl

Ishii, I.; Suzuki, D.; Umeno, T.; Kurata, Y.; Wada, Y.; Suzuki, T.; Andreev, A. V.; Gorbunov, D.; Miyata, A.; Zherlitsyn, S.; Wosnitza, J.

The hexagonal Dy-based compound DyNiAl undergoes ferromagnetic and antiferromagnetic-type magnetic phase transitions at TC = 30 K and T1 = 15 K, respectively. To investigate the 4f -electronic state and quadrupole interactions in DyNiAl, we carried out ultrasonic measurements versus temperature and applied magnetic field. The transverse elastic moduli C44 and C66 show a prominent elastic softening originating from an interlevel ferroquadrupolar-type interaction between the ground state and excited Kramers doublets, clarified by a crystal field analysis. In magnetic fields applied along the [100] and [001] axes, we observed a field-induced phase transition. Because the quadrupole interaction is enhanced in high magnetic fields according to our calculations, we suggest a magnetic-field-induced ferroquadrupolar ordering of the electric quadrupoles Oxy and Oyz for fields applied along [100] and [001], respectively, with different quadrupolar order parameters depending on the field direction.

Permalink: https://www.hzdr.de/publications/Publ-32692
Publ.-Id: 32692


Easy Diagram Creation in GitLab

Huste, T.; Jandt, U.

Recently, the Helmholtz-wide software development platform (Gitlab) has been extended with the ability to create diagrams from textual descriptions. This post will help you getting started with this new feature.

Keywords: GitLab; Software; Diagrams; UML; Markdown

Permalink: https://www.hzdr.de/publications/Publ-32691
Publ.-Id: 32691


Aktuelle Entwicklungen aus den Radiopharmazeutischen Wissenschaften für theranostische Anwendungen - Editorial

Mamat, C.; Kopka, K.

Die klinische Bereitstellung von Radiopharmaka für diagnostische und therapeutische Zwecke ist eine der zentralen Aufgaben der konventionellen Radiopharmazie, denn sie ist das Herzstück einer jeden modernen Nuklearmedizin. Neben einem großen, aber planbaren, logistischen Aufwand ist die Versorgung mit Radiopharmaka sowohl mit radiochemischen als auch regulatorischen Herausforderungen verbunden. Das betrifft beispielsweise die zuverlässige Verfügbarkeit einzelner Radionuklide aufgrund ihrer Kurzlebigkeit und die Erfüllung obligatorischer Qualitätskontrollen.
Daneben widmen sich die Radiopharmazeutischen Wissenschaften ihrem Forschungsauftrag, der in der Erforschung neuer Radionuklide, der Entwicklung und der (prä-)klinischen Testung neuer Radiopharmaka für Diagnose und Therapie und der Weiterentwicklung der bildgebenden Verfahren SPECT und PET
sowie der hybriden Kombinationen mit MRT und CT, besteht. In diesem Sinne ist diese Ausgabe des Nuklearmediziners ganz den neuesten Entwicklungen auf dem Gebiet der Radiopharmazie gewidmet, welche sich mittlerweile über klassische Ansätze hin zu theranostischen Anwendungen in Form von diagnose-geleiteten Therapien entfaltet.

Keywords: Nuklearmedizin; Radiopharmazeutische Wissenschaften

Permalink: https://www.hzdr.de/publications/Publ-32690
Publ.-Id: 32690


An introduction to the Materials Learning Algorithm (MALA) python package

Fiedler, L.

Density Functional Theory (DFT) is one of the most popular quantum mechanical simulation methods, since it balances sufficient accuracy with reasonable computational cost. It is often used in material science applications at ambient and extreme conditions. Nonetheless, DFT approaches its limits in terms of computational feasbility when faced with simulation problems at larger time and length scales, especially at temperatures >> 0K. Surrogate models based on neural networks can circumvent these limitations. By training a neural network to predict properties of interest (total energy, atomic forces) based on atomic configurations, predictions with DFT-like accuracy can be done at a fraction of the computational cost. At CASUS, the Matter under Extreme Conditons department is currently developing the Materials Learning Algorithm (MALA) python package, a modular open-source python package intended to serve as a toolbox for efficiently building these surrogate models. MALA enables users to preprocess DFT data, train networks and postprocess results using only a few lines of code.

Keywords: Density Functional Theory; Machine Learning; Neural Networks

  • Open Access Logo Lecture (others) (Online presentation)
    CASUS institute seminar, 06.04.2021, Görlitz, Deutschland

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-32688
Publ.-Id: 32688


Quenching Mechanism of Uranyl(VI) by Chloride and Bromide in Aqueous and Non-Aqueous Solutions

Haubitz, T.; Drobot, B.; Tsushima, S.; Steudtner, R.; Stumpf, T.; Kumke, M. U.

A major hindrance in utilizing uranyl(VI) luminescence as a standard analytical tool, for example, in environmental monitoring or nuclear industries, is quenching by other ions such as halide ions, which are present in many relevant matrices of uranyl(VI) speciation. Here, we demonstrate through a combination of time-resolved laser-induced fluorescence spectroscopy, transient absorption spectroscopy, and quantum chemistry that coordinating solvent molecules play a crucial role in U(VI) halide luminescence quenching. We show that our previously suggested quenching mechanism based on an internal redox reaction of the 1:2-uranyl−halide-complex holds also true for bromide-induced quenching of uranyl(VI). By adopting specific organic solvents, we were able to suppress the separation of the oxidized halide ligand X2·− and the formed uranyl(V) into fully solvated ions, thereby “reigniting” U(VI) luminescence. Time-dependent density functional theory calculations show that quenching occurs through the outer-sphere complex of U(VI) and halide in water, while the ligand-tometal charge transfer is strongly reduced in acetonitrile.

Permalink: https://www.hzdr.de/publications/Publ-32687
Publ.-Id: 32687


Divalent ion selectivity in capacitive deionization with vanadium hexacyanoferrate: Experiments and quantum-chemical computations

Singh, K.; Li, G.; Zuilhof, H.; Lee, J.; Mehdi, B. L.; Zornitta, R. L.; de Smet, L. C. P. M.

Selective removal of ions from water, via capacitive deionization (CDI), is relevant for
environmental and industrial applications like water purification, softening, and
resource recovery. Prussian blue analogues (PBAs) are proposed as an electrode
material for selectively removing cations from water, based on their size. So far, PBAs
used in CDI have been selective towards monovalent ions. Here, we introduce
vanadium hexacyanoferrate (VHCF), a PBA, as a new electrode material in a hybrid
CDI setup, to selectively remove divalent cations from water.
These electrodes preferred divalent Ca 2+ over monovalent Na + , with a separation
factor, β Ca/Na ≈ 3.5. This finding contrasts the observed monovalent ion selectivity
by PBA electrodes. This opposite behavior was rationalized by Density Functional
Theory (DFT) simulations. Furthermore, the coating of the VHCF electrodes with a
conducting polymer (poly-pyrrole, doped with poly-styrenesulphonate, PPy/PSS)
prevented the contamination of the treated water following the degradation of the
electrode. This facile and modular coating method can be effortlessly extended to other
PBA electrodes, limiting the extent of treated water contamination during repeated
cycling in CDI. This study paves the way for tunable selectivity while extending the
library of electrodes that can be successfully used in (selective) CDI.

Keywords: Intercalation; capacitive deionization; Prussian Blue analogs; ion selectivity; DFT simulation

Permalink: https://www.hzdr.de/publications/Publ-32686
Publ.-Id: 32686


Dataset and simulation program for "Limitation of THz conversion efficiency in DSTMS pumped by intense femtosecond pulses"

Li, J.; Rana, R.; Zhu, L.; Liu, C.; Schneider, H.; Pashkin, O.

- Raw experimental data of the measured THz and OPA spectra

- Origin file with the experimentally measured THz conversion efficienbcy as a function of the OPA fluence

- Matlab program for the simulation of the THz generation process in DSTMS

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-05-31
    DOI: 10.14278/rodare.997

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-32684
Publ.-Id: 32684


GLS-driven glutamine catabolism contributes to prostate cancer radiosensitivity by regulating the redox state, stemness and ATG5-mediated autophagy

Mukha, A.; Kahya, U.; Linge, A.; Chen, O.; Löck, S.; Lukiyanchuk, V.; Richter, S.; Alves, T.; Peitzsch, M.; Telychko, V.; Skvortsov, S.; Negro, G.; Aschenbrenner, B.; Skvortsova, I.-I.; Kunz-Schughart, L.; Baretton, G.; Baumann, M.; Krause, M.; Peitzsch, C.; Dubrovska, A.

Abstract
Radiotherapy is one of the curative treatment options for localized prostate cancer (PCa). The curative potential of radiotherapy is mediated by irradiation-induced oxidative stress and DNA damage in tumor cells. However, PCa radiocurability can be impeded by tumor resistance mechanisms and normal tissue toxicity. Metabolic reprogramming is one of the major hallmarks of tumor progression and therapy resistance. Specific metabolic features of PCa might serve as therapeutic targets for tumor radiosensitization and as biomarkers for identifying the patients most likely to respond to radiotherapy. The study aimed to characterize a potential role of glutaminase (GLS)-driven glutamine catabolism as a prognostic biomarker and a therapeutic target for PCa radiosensitization.
Methods: We analyzed primary cell cultures and radioresistant (RR) derivatives of the conventional PCa cell lines by gene expression and metabolic assays to identify the molecular traits associated with radiation resistance. Relative radiosensitivity of the cell lines and primary cell cultures were analyzed by 2-D and 3-D clonogenic analyses. Targeting of glutamine (Gln) metabolism was achieved by Gln starvation, gene knockdown, and chemical inhibition. Activation of the DNA damage response (DDR) and autophagy was assessed by gene expression, western blotting, and fluorescence microscopy. Reactive oxygen species (ROS) and the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) were analyzed by fluorescence and luminescence probes, respectively. Cancer stem cell (CSC) properties were investigated by sphere-forming assay, CSC marker analysis, and in vivo limiting dilution assays. Single circulating tumor cells (CTCs) isolated from the blood of PCa patients were analyzed by array comparative genome hybridization. Expression levels of the GLS1 and MYC gene in tumor tissues and amino acid concentrations in blood plasma were correlated to a progression-free survival in PCa patients.
Results: Here, we found that radioresistant PCa cells and prostate CSCs have a high glutamine demand. GLS-driven catabolism of glutamine serves not only for energy production but also for the maintenance of the redox state. Consequently, glutamine depletion or inhibition of critical regulators of glutamine utilization, such as GLS and the transcription factor MYC results in PCa radiosensitization. On the contrary, we found that a combination of glutamine metabolism inhibitors with irradiation does not cause toxic effects on nonmalignant prostate cells. Glutamine catabolism contributes to the maintenance of CSCs through regulation of the alpha-ketoglutarate (α-KG)-dependent chromatin-modifying dioxygenase. The lack of glutamine results in the inhibition of CSCs with a high aldehyde dehydrogenase (ALDH) activity, decreases the frequency of the CSC populations in vivo and reduces tumor formation in xenograft mouse models. Moreover, this study shows that activation of the ATG5-mediated autophagy in response to a lack of glutamine is a tumor survival strategy to withstand radiation-mediated cell damage. In combination with autophagy inhibition, the blockade of glutamine metabolism might be a promising strategy for PCa radiosensitization. High blood levels of glutamine in PCa patients significantly correlate with a shorter prostate-specific antigen (PSA) doubling time. Furthermore, high expression of critical regulators of glutamine metabolism, GLS1 and MYC, is significantly associated with a decreased progression-free survival in PCa patients treated with radiotherapy.
Conclusions: Our findings demonstrate that GLS-driven glutaminolysis is a prognostic biomarker and therapeutic target for PCa radiosensitization.

Keywords: Prostate cancer; Radioresistance; Cancer stem cells; Autophagy; GLS1

Permalink: https://www.hzdr.de/publications/Publ-32683
Publ.-Id: 32683


Tuning capacitance wire-mesh sensor gains for measurement of conductive fluids

de Assis Dias, F.; Wiedemann, P.; Da Silva, M. J.; Schleicher, E.; Hampel, U.

In this paper, the front-end circuit of a capacitance wire-mesh sensor (WMS) is analyzed in detail and a new methodology to tune its feedback gains is reported. This allows, for the first time, a capacitance WMS to be able to provide linear measurements of multiphase fluids with electrical conductivity greater than 100 uS/cm, which is particularly important for tap water, where the conductivity is typically in between 100-500 uS/cm. Experimental and numerical results show that the selected gains using the proposed methodology contribute to suppress cross-talk and energy losses, which in turn, reduces considerably the deviation of the conductivity measurement and the estimation of derived flow parameters, such as local and average phase fraction.

Keywords: capacitance wire-mesh sensor; multiphase flow; electronic circuit modelling; finite-element method

Related publications

Permalink: https://www.hzdr.de/publications/Publ-32681
Publ.-Id: 32681


Dataset: Measuring the structure and equation of state of polyethylene terephthalate at megabar pressures

Lütgert, B. J.; Vorberger, J.; Hartley, N.; Voigt, K.; Rödel, M.; Schuster, A.; Benuzzi-Mounaix, A.; Brown, S.; Cowan, T.; Cunningham, E.; Döppner, T.; Falcone, R. W.; Fletcher, L. B.; Galtier, E.; Glenzer, S. H.; Laso García, A.; Gericke, D. O.; Heimann, P. A.; Lee, H. J.; McBride, E. E.; Pelka, A.; Prencipe, I.; Saunders, A. M.; Schölmerich, M.; Schörner, M.; Sun, P.; Vinci, T.; Ravasio, A.; Kraus, D.

This repository contains raw-data related to our publication "Measuring the structure and equation of state of polyethylene terephthalate at megabar pressures".

The XRD data in the "LCLS" folder is accompanied with a "calibration.poni" file that provides information about the experiment's geometry and can be used in pyFAI (GitHub page) or Dioptas (GitHub page) to integrate the two-dimensional data azimuthally. Integrated XRD data after background-subtraction and filter-corrections is presented in Fig. 2 and 3 of the manuscript while 2D data of run 215 is used in Fig. 1. The "shotlist.csv" file contains information about the relative X-ray to drive-laser timing, shot-type and X-ray energy for the individual events.

VISAR, SOP and reflectivity measurements can be found in the "LULI" directory. 2ω-VISAR and SOP datasets of shot 08 are displayed as inserts in Fig. 5 (the first after performing a ghost-fringe subtraction). "shotlist.csv" provides additional parameters.

The DFTMD folder contains the results of our density functional theory molecular dynamics simulation.
In the "XRD" subdirectory, "wrofk_mylar_chomd*.dat" files can be found in which the quantities to calculate the lineouts in Fig. 3 and 4 are saved for given temperatures, pressures and densities. The header of those files is given in "header.txt" and additional information about the conditions and settings for individual calculations can be obtained from "param_mylar_md.txt".
The dataset for the Hugoniot curve from our DFT-MD equation-of-state (which is plotted in Fig. 5) is provided in the "Hugoniot" sub-folder.

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-05-27
    DOI: 10.14278/rodare.993
    License: CC-BY-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-32679
Publ.-Id: 32679


Nanomagnetism and spintronics of Cr2O3 thin-film 
magnetoelectric antiferromagnets

Makarov, D.

Thin film magnetoelectric antiferromagnets (AF) is a viable material science platform for prospective high speed and energy efficient spintronic devices for memory and logic applications. To explore their application potential, it is necessary to understand modifications of the magnetic properties of AF thin films with respect to their bulk counterparts. Here, we will discuss spintronics, magnetometry and microscopy of bulk α-Cr2O3 single crystals [1] and relate them to the properties of α-Cr2O3 thin films [2-5]. In transport experiments, we access the magnetic state of the Cr2O3 relying on the spin Hall physics in a Pt thin film brought in proximity to the insulating antiferromagnet [2-4]. The analysis of the transport data is backed up by the real space imaging of AF domain patterns using NV microscopy [1,5]. Considering grainy morphology of thin films, we address questions regarding the change of the intergranular exchange [5], criticality behavior and switching of the order parameter [2] and physics of the readout signal in α-Cr2O3 interfaced with Pt [3]. In particular, the possibility to read-out the antiferromagnetic order parameter all-electrically enables a new recording concept of antiferromagnetic magnetoelectric random access memory (AF-MERAM) [3]. Furthermore, relying on the elasticity of antiferromagnetic domain walls in Cr2O3 single crystals and exploring their efficient pinning at lithographically defined mesa structures, the concept of domain wall based antiferromagnetic memory was put forth [1].

1. N. Hedrich, K. Wagner, O. V. Pylypovskyi, B. J. Shields, T. Kosub, D. D. Sheka, D. Makarov, P. Maletinsky, Nature Physics, (2021), doi:10.1038/s41567-020-01157-0.
2. T. Kosub, M. Kopte, F. Radu, O. G. Schmidt, D. Makarov, Physical Review Letters, 115 (2015) 097201.
3. T. Kosub, M. Kopte, R. Hühne, P. Appel, B. Shields, P. Maletinsky, R. Hübner, M. O. Liedke, J. Fassbender, O. G. Schmidt, D. Makarov, Nature Communications, 8 (2017) 13985.
4. R. Schlitz, T. Kosub, A. Thomas, S. Fabretti, K. Nielsch, D. Makarov, S. T. B. Goennenwein, Applied Physics Letters, 112 (2018) 132401.
5. P. Appel, B. J. Shields, T. Kosub, R. Hübner, J. Fassbender, D. Makarov, P. Maletinsky, Nano Letters, 19 (2019) 1682.

Keywords: antiferromagnetic spintronics

  • Invited lecture (Conferences) (Online presentation)
    3rd International Conference on Advances in Functional Materials, 18.08.2021, Los Angeles, USA

Permalink: https://www.hzdr.de/publications/Publ-32678
Publ.-Id: 32678


Highly compliant flexible and printable magnetoelectronics for human-machine interfaces and soft robotics

Makarov, D.

Motion sensing is the primary task in numerous disciplines including industrial robotics, prosthetics, virtual and augmented reality appliances. In rigid electronics, rotations, displacements and vibrations are typically monitored using magnetic field sensors. Here, we will discuss the fabrication of flexible, stretchable and printable magnetoelectronic devices. The technology platform relies on high-performance magnetoresistive and Hall effect sensors deposited or printed on ultrathin polymeric foils. These skin compliant flexible and printable magnetosensitive elements enable touchless interactivity with our surroundings based on the interaction with magnetic fields, which is relevant for smart skins, soft robotics and human-machine interfaces.

Keywords: flexible magnetic field sensors; flexible electronics; printed electronics

  • Invited lecture (Conferences) (Online presentation)
    2021 IEEE International Flexible Electronics Conference (IFETC), 09.08.2021, Glenview, USA

Permalink: https://www.hzdr.de/publications/Publ-32677
Publ.-Id: 32677


Flexible magnetic field sensor technologies

Makarov, D.

Conventional magnetic field sensors are fabricated on flat substrates and are rigid. Extending 2D structures into 3D space relying on the flexible electronics approaches allows to enrich conventional or to launch novel functionalities of spintronic-based devices by tailoring geometrical curvature and 3D shape. Here, we will briefly review fundamentals of 3D curved magnetic thin films [1] and primarily focus on their application potential for eMobility [2,3], consumer electronics, virtual and augmented reality [4-7] appliances. The technology platform relies on high-performance magnetoresistive and Hall effect sensors fabricated on ultrathin polymeric foils [8] and paves the way towards skin-compliant devices enabling touchless interactivity with our surroundings. Flexile magnetosensitive elements impact emerging research and technology fields of smart skins, soft robotics and human-machine interfaces. In this talk, recent fundamental and technological advancements on flexible magnetoelectronics will be reviewed.

[1] R. Streubel, D. Makarov et al., J. Phys. D: Appl. Phys. (Review) 49, 363001 (2016).
[2] M. Melzer, D. Makarov et al., Adv. Mater. 27, 1274 (2015).
[3] I. J. Mönch, D. Makarov et al., IEEE Trans. Magn. 51, 4004004 (2015).
[4] G. S. Cañón Bermúdez, D. Makarov et al., Science Advances 4, eaao2623 (2018).
[5] G. S. Cañón Bermúdez, D. Makarov et al., Nature Electronics 1, 589 (2018).
[6] P. N. Granell, D. Makarov et al., npj Flexible Electronics 3, 3 (2019).
[7] J. Ge, D. Makarov et al., Nature Communications 10, 4405 (2019).
[8] D. Makarov et al., Appl. Phys. Rev. (Review) 3, 011101 (2016).

Keywords: flexible magnetic field sensors; flexible electronics; curvilinear magnetism

  • Invited lecture (Conferences) (Online presentation)
    SPIE Spintronics Symposium 2021: Nanoscience + Engineering, 02.08.2021, San Diego, USA

Permalink: https://www.hzdr.de/publications/Publ-32676
Publ.-Id: 32676


Micromagnetism of magnetoelectric collinear antiferromagnets

Makarov, D.

In this talk I will review our recent activities on curvilinear and magnetoelectric antiferromagnets.

Keywords: antiferromagnetic spintronics; curvilinear magnetism

  • Invited lecture (Conferences) (Online presentation)
    PetaSpin: Virtual Workshops and Seminars 2021, 15.10.2021, Messina, Italy

Permalink: https://www.hzdr.de/publications/Publ-32675
Publ.-Id: 32675


Curvilinear magnetism

Makarov, D.

Conventional magnetic field sensors are fabricated on flat substrates and are rigid. Extending 2D structures into 3D space relying on the flexible electronics approaches allows to enrich conventional or to launch novel functionalities of spintronic-based devices. The lack of an inversion symmetry and the emergence of a curvature induced effective anisotropy and Dzyaloshinskii-Moriya interaction (DMI) are characteristic of curved surfaces, leading to curvature-driven magnetochiral responses and topologically induced magnetization patterning. The possibility to tailor magnetic responses by geometry of the object is a new approach to material science, which allows to obtain a desired functionality of spintronic and spin-orbitronic devices yet without the need to rely on the optimization of the intrinsic material properties. Here, we will review fundamentals of 3D curved magnetic thin films and focus on their applications in eMobility, virtual and augmented reality, soft robotics, and human-machine interfaces.

Keywords: curvature effects in magnetism; flexible magnetic field sensors

  • Invited lecture (Conferences) (Online presentation)
    W2S Seminar (Webinar series on Spintronics), 25.03.2021, Khurda, India

Permalink: https://www.hzdr.de/publications/Publ-32674
Publ.-Id: 32674


Der sechste Sinn – Magnetfelder verändern den Alltag

Makarov, D.

Magnetic fields are not visible. As humans we know cannot feel them. In contrast to birds, we humans do not use them for navigation. There might be even an impression that magnetic fields are of very limited relevance for our everyday life. This is in strong contrast to the fact that the magnetic field of the Earth protects life from dangerous cosmic radiation, that there are numerous magnetic field sensors, which are implemented in devices around us including electronic compasses in our cellphones, crucial component of motors in electrical cars, even level of water in our coffee machines is measured using magnetic field sensors. Our society with all known industrial and technology revolutions is not thinkable without the use of magnetic fields and magnetic field sensors. Still, this is an established fact that for thousands of years humans believed that they are not susceptible to magnetic fields. Therefore, in contrast to vision, audio or haptic perception, magnetic field as an information channel was not considered seriously for humans.
The situation changed very recently. New studies show that similar to birds, mammals including humans also feel geomagnetic fields, the property which is called magnetoception. Although this sense for humans is still to be understood, we are working on the realisation of artificial magnetoception. We design and fabricate electronic skins - magnetosensitive devices prepared on mechanically soft and compliant support, which does not disturb our everyday activity when applied to skin or integrated in a textile. Mit unserer hochempfindlichen, aber tragbaren und sogar implantierbaren Sensorplattform möchten wir die Magnetorezeption quasi in einen „Sechsten-Sinn“ verwandeln. Die Anwendungsmöglichkeiten dieser Technologie sind kaum zu überschätzen und tangieren viele wichtige gesellschaftliche Bereiche; von der Informationstechnologie, über die Halbleitertechnologie, die E-Mobilität bis zur Realisierung neuartiger Mensch-Maschine-Schnittstellen zur Hilfe bei schweren Erkrankungen.

Keywords: flexible magnetic field sensors; flexible electronics; printed electronics

  • Lecture (others)
    Campus Talks, 08.06.2021, Berlin, Germany

Permalink: https://www.hzdr.de/publications/Publ-32673
Publ.-Id: 32673


FLEXISENS - ultra-thin magnetic field sensor for new fields of application

Makarov, D.

The Helmholtz Innovation Lab “FlexiSens” focuses on the development and application of a flexible and printable magnetic field sensors (Hall effect and magneto-resistive effects). We have developed novel high-performance magnetic field sensors on ultra-thin flexible substrates that have a high mechanical adaptability. Due to their extremely thin and unconventional mechanical properties, flexible and printed sensors can be used not only on various flat, but also curved objects. Our technology enables new fields of application, for example as wearable electronics on the skin, as smart implants in medicine or for monitoring movements in large glass or roof structures.

Keywords: flexible magnetic field sensors; flexible electronics; printed electronics

  • Lecture (Conference) (Online presentation)
    15th Silicon Saxony Day, 27.05.2021, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-32672
Publ.-Id: 32672


Critical Diameter for Lift Reversal of Bubbles in Linear Shear Flows

Hayashi, K.; Lucas, D.; Legendre, D.; Tomiyama, A.

The lift coeffcient C_L of a bubble in a shear flow is known to change its sign depending on the bubble shape, i.e. C_L of spherical bubbles are positive for any the bubble Reynolds numbers while those of ellipsoidal bubbles can be negative due to the deformation-induced negative lift. The critical bubble diameter, d_C, for the lift reversal was discussed in this study by making use of available CL correlations for clean bubbles in linear shear flows. As a result, the following conclusions were obtained: (1) the C_L correlations well describe the complex characteristics of d_C and the lift reversal criterion in terms of Re_C is well reproduced with the correlations, (2) in the surface tension and inertial force dominant regime, the critical Eötvös and Weber numbers can be used to develop a simple criterion of lift reversal, i.e.they are almost constant, and the Capillary number for d_C can be expressed in terms of the Morton number only, M; these dimensionless groups in the viscous force dominant regime, however, show more complex dependence on M, and (3) the critical Ohnesolge number, Oh_C, monotonically increases with increasing M even in the viscous force dominant regime.

Keywords: lift force; lift reversal; negative lift; shape deformation

Permalink: https://www.hzdr.de/publications/Publ-32671
Publ.-Id: 32671


Limitation of THz conversion efficiency in DSTMS pumped by intense femtosecond pulses

Li, J.; Rana, R.; Zhu, L.; Liu, C.; Schneider, H.; Pashkin, O.

Terahertz (THz) generation via optical rectification (OR) of near-infrared femtosecond pulses in DSTMS is systematically studied using a quasi-3D theoretical model, which takes into account cascaded OR, three-photon absorption (3PA) of the near-infrared radiation, and material dispersion/absorption properties. The simulation results and the comparison with experimental data for pump pulses with the center wavelength of 1.4 μm indicate that the 3PA process is one of the main limiting factors for THz generation in DSTMS at high pump fluences. The THz conversion efficiency is reduced further by the enhanced group velocity dispersion effect caused by the spectral broadening due to the cascaded OR. We predict that for broadband pump pulses with a duration of 30 fs, the THz conversion efficiency can be enhanced by a factor of 1.5 by using a positive pre-chirping that partially suppresses the cascaded OR and the 3PA effects.

Related publications

Permalink: https://www.hzdr.de/publications/Publ-32670
Publ.-Id: 32670


Recent developments in modelling of polymer electrochemical cells

Beale, S.; Zhang, S.; Hess, S.; Reimer, U.; Weber, N.; Marschall, H.; Lehnert, W.

Polymer electrolyte electrochemical cells (PECs) offer exciting possibilities as energy converters in the form of both fuel cells and electrolyzers. Computational fluid dynamics can be used to analyse the performance of virtual prototypes at the micro-scale, as well as the cell and stack levels. This presentation details a comprehensive program of development of open source tools to describe and predict PEC operation. The software employed is OpenFOAM, which mimics the governing partial differential equations that describe the physics of PEC behaviour. Models range from detailed two-phase flow in porous transport layers based on digital reconstructions and the volume of fluid method, through single and multi-fluid cell models employing Eulerian-Eulerian solvers, to stack-level models whereby volume averaging also known as local homogenization is employed for both single-phase and two-phase formulations. The development of a multi-phase stack model represents an original and novel scheme not previously published.
The results of mathematical calculations are compared with analytical solutions for one-dimensional idealizations, previous three-dimensional (3-D) numerical work by other researchers, and detailed experimental data gathered in-house. Comparisons are made in terms of local current density and species mass/molar fractions, as well as current density vs. voltage, i.e., polarization characteristics. Different levels of model complexity are also considered, for instance comparisons of a 2-D electrochemical formulation based on a Kirchhoff-Ohm equation (ideal potential less losses/over-potentials) vs. a fully 3-D simulation of both ionic and protonic potential fields. The presentation concludes with an assessment of the needs/requirements of the next generation of PEC analysis tools.

  • Lecture (Conference)
    8th International Symposium on Advances in Computational Heat Transfer CHT-21, 15.-19.08.2021, Rio De Janeiro, Brasilien

Permalink: https://www.hzdr.de/publications/Publ-32669
Publ.-Id: 32669


KLOE hadronic cross section data in the HepDATA repository

Müller, S.

Presentation at "PrecisionSM" Working Group Meeting, 26.5.2021 (virtual)

Keywords: HEPData; STRONG2020

  • Lecture (Conference) (Online presentation)
    3rd Meeting on database on hadronic cross sections, 26.05.2021, Europ/Rome (virtual), Italy

Permalink: https://www.hzdr.de/publications/Publ-32667
Publ.-Id: 32667


Epileptogenic zone detection in MRI negative epilepsy using adaptive thresholding of arterial spin labeling data

Gajdoš, M.; Říha, P.; Kojan, M.; Doležalová, I.; Mutsaerts, H. J. M. M.; Petr, J.; Rektor, I.

Drug-resistant epilepsy is a diagnostic and therapeutic challenge, mainly in patients with negative MRI findings. State-of-the-art imaging methods complement standard epilepsy protocols with new information and help epileptologists to increase the reliability of their decisions. In this study, we investigate whether arterial spin labeling (ASL) perfusion MRI can help localize the epileptogenic zone (EZ). To that end, we developed an image processing method to detect the EZ as an area with hypoperfusion relative to the contralateral unaffected side, using subject-specific thresholding of the asymmetry index in ASL images. We demonstrated three thresholding criteria (termed minimal product criterion, minimal distance criterion, and elbow criterion) on 29 patients with MRI-negative epilepsy (age 32.98 ± 10.4 years). The minimal product criterion showed optimal results in terms of positive predictive value (mean 0.12 in postoperative group and 0.22 in preoperative group) and true positive rate (mean 0.71 in postoperative group and 1.82 in preoperative group). Additionally, we found high accuracy in determining the EZ side (mean 0.86 in postoperative group and 0.73 in preoperative group out of 1.00). ASL can be easily incorporated into the standard presurgical MR protocol, and it provides an additional benefit in EZ localization.

Permalink: https://www.hzdr.de/publications/Publ-32666
Publ.-Id: 32666


Curvilinear Antiferromagnetism: Current State and Perspectives

Pylypovskyi, O.

Antiferromagnets (AFMs) emerged as a versatile material science platform, which enabled numerous fundamental discoveries including the observation of monopole quasiparticles in frustrated systems and collective quantum effects, such as spin superfluidity and Bose–Einstein condensation of magnetic excitations [1]. Primary advantages of antiferromagnets are their terahertz operating frequencies, the absence of stray fields, magnetic field robustness, all of which result in numerous advantages including those in spintronics and spinorbitronics [2]. The key enabler of those applications is the presence of the Dzyaloshinskii-Moriya interaction (DMI). This, in turn, put stringent requirements on the magnetic symmetry of AFM, which should support weak ferromagnetism and chiral helimagnetism. This makes the portfolio of material systems available for these studies very limited that renders the progress in AFM-related fundamental and technological research to depend on time-consuming material screening and optimization of intrinsic chiral properties of AFMs. The field of curvilinear magnetism is well explored for ferromagnets, where magnetic responses are tailored by local curvatures [3]. By contrast, the topic of curvilinear AFMs is at its infancy [4-9]. The energy landscape of ring AFM and geometrically frustrated chains at non-zero temperature is characterized by a large number of metastable states including long-living noncollinear textures if anisotropy is strong enough [6]. In experiment, curvilinear AFMs are mainly represented by the molecular magnets [7] and metalized DNA molecules [8]. The shape anisotropy stemming from magnetostriction plays the major role in the ordering of the Neel vector in perovskite zig-zag stripes and nanodots determining the easy direction as the parallel or perpendicular to the boundary [9]. In this presentation, we will demonstrate that chiral responses of AFMs can be tailored by a geometrical curvature without the need to adjust material parameters. In a general case, an intrinsically achiral one-dimensional curvilinear AFM spin chain behaves as a chiral helimagnet with geometrically tunable DMI, orientation of the Neel vector and the helimagnetic phase transition, see Fig. 1 [4]. The helix-shaped spin chain possesses two ground states: the so-called homogeneous and periodic ones with respect to the motion along the chain. The energetically favorable state is determined by the direction of the geometry-driven DMI vector. In contrast to ferromagnets, there is no easy axis anisotropy competing with the geometry-driven one. Furthermore, the curvature-induced DMI results in the hybridization of spin wave modes. The low-frequency branch is gapless for straight chains and possesses the gap for any finite curvature. In addition, the DMI enables a geometrically-driven local minimum of the low frequency branch which increases for larger curvature and torsion, see Fig. 2. This opens exciting perspectives to study long-lived collective magnon states in AFMs. These findings position curvilinear 1D antiferromagnets as a novel platform for the realization of geometrically tunable chiral antiferromagnets for antiferromagnetic spinorbitronics and fundamental discoveries in the formation of coherent magnon condensates in the momentum space. The proposed description of vector fields living at curvilinear geometries can be applied for other systems with complex order parameters, such as ferroelectrics [10] or liquid crystals [11].

[1] C. Castelnovo, R. Moessner, S. L. Sondhi, Nature, Vol. 451, p. 42 (2008); N. Nagaosa, Y. Tokura, Phys. Scr. Vol. T146, p. 014020 (2012);
A. A. Zvyagin, Low Temp. Phys. Vol. 39, p. 901 (2013) [2] T. Jungwirth, J. Sinova, A. Manchon et al, Nat. Phys. Vol. 14, p. 200 (2018); V. Baltz,
A. Manchon, M. Tsoi et al, Rev. Mod. Phys. Vol. 90, p. 015005 (2018) [3] R. Streubel, P. Fischer, F. Kronast et al, J. Phys. D: Appl. Phys. Vol. 49,
p. 363001 (2016); A. Fernandez-Pacheko, R. Streubel, O. Fruchart et al, Nat. Comm. Vol. 8, p. 15756 (2016); D. D. Sheka, O. V. Pylypovskyi, P.
Landeros et al., Comm. Phys. 3, 128 (2020) [4] O. V. Pylypovskyi, D. Y. Kononenko, K. V. Yershov et al, Nano Lett. Vol. 20, p. 8157 (2020) [5]
K. K. Nanda, A. W. Addison, E. Sinn et al, Inorg. Chem. Vol 35, p. 5966 (1996); O. Cador, D. Gatteschi, R. Sessoli et al, Ang. Chem. Int. Ed. vol 43,
p. 5196 (2004); M. Grzelczak, M. Correa-Duarte, V. Salgueirino-Maceira et al, Ang. Chem. Int. Ed. Vol. 46, p. 7026 (2007); T. Guidi, B. Gillon, S. A.
Mason et al, Nat. Comm. Vol. 6, p. 7061 (2015) [6] S. Castillo-Sepulveda, R. A. Escobar, D. Altbir et al, Phys. Rev. B, Vol. 96, p. 024426 (2017) [7] S.
J. Blundell, F. L. Pratt, J. Phys.: Cond. Matt. Vol. 16, p. R71 (2004) [8] K. Mizoguchi, S. Tanaka, M. Ojima et al, J. Phys. Soc. Jap. Vol. 76, p. 043801
(2007) [9] A. D. Bang, I. Hallsteinsen, R. V. Chopdekar et al, Appl. Phys. Lett. Vol. 115, p. 112403 (2019); M. S. Lee, P. Lyu, R. V. Chopdekar et al,
J. Appl. Phys. Vol. 127, p. 203901 (2020) [10] M. Owczarek, K. A. Hujsak, D. P. Ferris et al, Nat. Comm. Vol. 7, p. 13108 (2016) [11] G. Napoli, L.
Vergori, Phys. Rev. Lett. Vol. 108, p. 207803 (2012)

Keywords: antiferromagnetism; curvilinear magnetism

  • Invited lecture (Conferences) (Online presentation)
    IEEE International Magnetic Virtual Conference INTERMAG21, 26.-30.04.2021, Online, Online

Permalink: https://www.hzdr.de/publications/Publ-32665
Publ.-Id: 32665


Domain Walls in Antiferromagnetic Samples With non-Trivial Surface Topography

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

Antiferromagnets (AFMs) have regained strong attention from the magnetism community especially with the advent of antiferromagnetic spintronics [1]. The key operational element of spintronic devices is represented by information carriers, such as domain walls (DWs) and skyrmions. The simplest AFM DW separates two regions with the opposite orientation of the Neel order parameter. Although highly relevant, the experimental studies of AFM DWs (visualization, dynamics, mechanics) are challenging because of strict requirements on measurement techniques to access their properties. Here, we overcome these limitations and conduct detailed, quantitative studies of the mechanics and the nanoscale properties of individual, antiferromagnetic DWs in a single crystal Cr2O3 – a room-temperature, magnetoelectric, insulating AFM [2]. Our results reveal a remarkably pristine DW behaviour, which is governed by DW energy minimization and boundary conditions, but largely unaffected by pinning or disorder – a “textbook example” of antiferromagnetic DW physics. In our experiment, the crystal’s (0001) surface is patterned by a grid of mesas with mean thickness and width t=166 nm and w=2400 nm, respectively. The DW is nucleated by means of magnetoelectric field cooling by inverting the electric bias field over opposite halves of the sample. The DW may also be dragged through the mesa pattern by a focused laser spot. The magnetic texture is imaged using Nitrogen Vacancy (NV) magnetometry [3]. We find that the DW mimics an elastic surface with specific mechanical properties, determined by the interaction with the topographic features of the sample where the DW is (i) deflected from the straight plane crossing the mesa; (ii) bent around mesa corners. To address the DW behaviour theoretically, we perform large-scale spin-lattice simulations with GPU speed-up [4]. The analytical Ansatz is developed based on the numerically-obtained, three-dimensional DW profile. All main features of the DW behaviour can be determined taking into account the nearest-neighbour exchange and uniaxial anisotropy for a general model of a bipartite AFM. Crossing the mesa, the DW experiences an S-shaped distortion observed at the mesa surface, which is the result of exchange-driven boundary conditions at the side faces of the mesa, see Fig. 1. Below the top surface, the DW possesses a twist to match this distortion with the straight plane far below the sample’s surface. We find that the DW surface is deflected from the plane over a characteristic depth of 0.34w. Comparison of the equilibrium DW direction in bulk and at the mesa’s top surface allows us to derive an effective Snell’s law for the DW behaviour at the sample’s surface with the given incidence and refraction angles θ1 and θ2. The effective refraction coefficient is determined by the analytical energy minimization and reads neff = 1 + 3.1t/w + O(θ1). Controlled manipulation via laser not only enables DW dragging through the mesa, but also pinning at mesa corners. The shape of the DW surface is governed by its intrinsic elasticity. In terms of mechanics of an elastic ribbon, the corresponding tension coefficient is determined by the temperature-dependent exchange stiffness and anisotropy coefficient. This allows for curved DW states in which it is pinned at the opposite mesa sides. Using mesas as bistable pinning sites, we propose a potential DW-based AFM memory concept. Here, the memory state “0” or “1” is associated with the direction of the Neel order parameter at the mesa surface. We have realized such pinning sites experimentally and have shown manipulation of the state via laser dragging. In summary, we realize engineered DW potentials and control over DW trajectories by topographic structuring and manipulation of the DW position by means. The physics of AFM DWs in a single crystal with non-trivial surface topography is described theoretically by means of spin-lattice simulations and analytical model. A novel nanoscale AFM memory architecture is suggested.

[1] T. Jungwirth, J. Sinova, A. Manchon et al, Nat. Phys. Vol. 14, p. 200 (2018); T. Jungwirth, X. Marti, P. Wadley et al, Nat. Nano. Vol. 11, p. 231 (2016); V. Baltz, A. Manchon, M. Tsoi et al, Rev. Mod. Phys. Vol. 90, p. 015005 (2018); O. V. Pylypovskyi, D. Y. Kononenko, K. V. Yershov et al, Nano Lett. Vol. 20, p. 8157 (2020) [2] N. Hedrich, K. Wagner, O. V. Pylypovskyi et al, arXiv:2009.08086 [3] L. Rondin, J.-P. Tetienne, T. Hingant et al, Rep. Prog. Phys. Vol. 77, p. 056503 (2014); N. Hedrich, D. Rohner, M. Batzer et al, Phys. Rev. Applied, Vol. 14, p. 064007 (2020) [4] SLaSi simulation package, http://slasi.knu.ua; O. V. Pylypovskyi, D. D. Sheka, Book of Abstracts, EUROPT Workshop, p. 11 (2013)

Keywords: Cr2O3; NV magnetometry; topography; surface; domain wall

  • Lecture (Conference) (Online presentation)
    IEEE International Magnetic Virtual Conference INTERMAG21, 26.-30.04.2021, Online, Online

Permalink: https://www.hzdr.de/publications/Publ-32664
Publ.-Id: 32664


Description of Symmetry-Breaking Effects in Curvilinear Ferromagnetic Shells

Sheka, D.; Pylypovskyi, O.; Landeros, P.; Kakay, A.; Makarov, D.

The behaviour of any physical system is governed by the order parameter, determined by the geometry of the physical space of the object, namely their dimensionality and curvature. Usually, the effects of curvature are described using local interactions only, e.g. local spin-orbit- or curvature-induced Rashba and Dzyaloshinskii-Moriya interactions (DMI). In the specific case of ferromagnetism, until recently, there was no analytical framework, which was treating curvature effects stemming from local [1] and non-local [2] interactions on the same footing. The lack of a proper theoretical foundation impedes the description of essential micromagnetic textures like magnetic domains, skyrmion-bubbles and vortices. Here, we present a micromagnetic theory of curvilinear ferromagnetic shells, which allows to describe the geometry-driven effects stemming from exchange and magnetostatics within the same framework [3]. A general description of magnetic curvilinear shells can be done using tangential derivatives of the unit magnetization vector. Tangential derivatives are represented by the covariant derivatives of in-surface components and the regular derivative of the normal magnetization component, normalized by the square root of the corresponding metric tensor coefficient. This allows to separate the explicit effects of curvature and spurious effects of the reference frame. The shape of a given thin shell can be determined by two principal curvatures k1 and k2, which are functions of coordinate. The respective classification of curvilinear surfaces operates with (i) developable surfaces, where one of the principal curvatures equals to zero; (ii) minimal ones, where the mean curvature k1 + k2 = 0; and (iii) the general case. The local geometry-driven energy contributions are represented by the DMI and anisotropy, whose coefficients are determined by powers of the principal curvatures. This allows to cancel the influence of one of the DMI terms for the developable surfaces for any magnetic texture. The magnetostatic interaction is a source of new chiral effects, which are essentially non-local in contrast to the conventional DMI. The physical origin is the non-zero mean curvature of a shell and the non-equivalence between the top and bottom surfaces of the shell. We demonstrate that the analysis of non-local effects in curvilinear thin shells can become more straightforward when introducing three magnetostatic charges. In this respect, in contrast to the classical approach by Brown [4], we split a conventional volume magnetostatic charge into two terms: (i) magnetostatic charge, governed by the tangent to the sample’s surface, and (ii) geometrical charge, given by the normal component of magnetization and the mean curvature. In addition to the shape anisotropy (local effect), there appear four additional non-local terms, determined by the surface curvature. Three of them are zero for any magnetic texture in shells with the geometry of minimal surfaces. The fourth term is determined by the non-equivalence of the top and bottom surfaces of the shell and becomes zero only for the special symmetries of magnetic textures. The discovered non-local magnetochiral effects introduce handedness in an intrinsically achiral material and enables the design of magneto-electric and ferro-toroidic responses. This will stimulate to rethink the origin of chiral effects in different systems, e.g. in fundamentally appealing and technologically relevant skyrmionic systems, and further theoretical investigations in the field of curvilinear magnetism as well as experimental validation of these theoretical predictions. These developments will pave the way towards new device ideas relying on curvature effects in magnetic nanostructures. The impact of effects predicted in this work goes well beyond the magnetism community. Our description of the vector field behaviour can be applied to different emergent field of studies of curvature effects. The prospective applications include curved superconductors [5], twisted graphene bilayers [6], flexible ferroelectrics [7], curved liquid crystals [8].

[1] Yu. Gaididei, V. P. Kravchuk, D. D. Sheka, Phys. Rev. Lett., 112, 257203 (2014); D. D. Sheka, V. P. Kravchuk, Yu. Gaididei, J. Phys. A: Math. Theor., 48, 125202 (2015); O. V. Pylypovskyi, V. P. Kravchuk, D. D. Sheka et al, Phys. Rev. Lett., 114, 197204 (2015); V. P. Kravchuk, D. D. Sheka, A. Kakay et al, Phys. Rev. Lett., 120, 067201 (2018) [2] P. Landeros, A. S. Nunez, J. Appl. Phys. Vol. 108, p. 033917 (2010); J. A. Otalora, M. Yan, H. Schultheiss et al, Phys. Rev. Lett., 117, 227203 (2016); J. A. Otalora, M. Yan, H. Schultheiss et al, Phys. Rev. B, 95, 184415 (2017) [3] D. D. Sheka, O. V. Pylypovskyi, P. Landeros et al., Comm. Phys. 3, 128 (2020) [4] W. F. Brown Jr. Micromagnetics (Wiley, New York, 1963) [5] V. Vitelly, A. M. Turner, Phys. Rev. Lett., 93, 215301 (2004) [6] W. Yan, W.-Y. He, Z.-D. Chu et al, Nat. Comm., 4, 2159 (2013) [7] M. Owczarek, K. A. Hujsak, D. P. Ferris et al, Nat. Comm., 7, 13108 (2016) [8] G. Napoli, L. Vergori, Phys. Rev. Lett., 108, 207803 (2012)

Keywords: curvilinear magnetism; magnetostatics; curvilinear geometry

  • Lecture (Conference) (Online presentation)
    IEEE International Magnetic Virtual Conference INTERMAG21, 26.-30.04.2021, Online, Online

Permalink: https://www.hzdr.de/publications/Publ-32663
Publ.-Id: 32663


Exploration of DVC (Data Version Control)

Sultova, N.

The repository contains tutorials and code which were created based on the exploration of DVC (Data Version Control) as a potential tool for managing machine learning pipelines within HZDR.
The tutorials aim to help understanding the tools features and drawbacks and also serve as future teaching material.

Keywords: machine learning version control pipelines

  • Software in the HZDR data repository RODARE
    Publication date: 2021-05-25
    DOI: 10.14278/rodare.991
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-32662
Publ.-Id: 32662


131Ba as a promising SPECT-diagnostic match for 223/224Radium

Reissig, F.; Bauer, D.; Ullrich, M.; Kreller, M.; Pietzsch, J.; Kopka, K.; Pietzsch, H.-J.; Walther, M.; Mamat, C.

We recognize 131Ba as a SPECT radionuclide, which provides a diagnostic match for the therapeutic alpha-emitting radionuclides 223Ra and 224Ra. The gamma-emitter barium-131 (t½ = 11.5 d) decays with an energy of 123.8 keV (30% intensity) of the first decay via cesium-131 (t½ = 9.7 d) to stable xenon-131, each by electron capture. Our aim was to develop of a straightforward resin-based radiochemical separation to yield 131Ba with high radionuclide purity. Furthermore, the radiolabeling of the complexing agent macropa with [131Ba]Ba2+ using mild labeling conditions was intended. For this purpose, different TLC systems as reaction control were utilized. The radiopharma-cological characterization of 131Ba-labeled macropa in comparison to uncomplexed [131Ba]Ba2+ was carried out in healthy mice, including biodistribution and small animal SPECT/CT experiments.

Keywords: alpha therapy; Barium-131; Radium-224; SPECT

  • Lecture (Conference) (Online presentation)
    eSRS 2021 Virtual Meeting, 17.-19.05.2021, Nantes, France
  • Abstract in refereed journal
    Nuclear Medicine and Biology 96-97/S1(2021), S107
    DOI: 10.1016/S0969-8051(21)00423-6

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  • Secondary publication expected from 17.05.2022

Permalink: https://www.hzdr.de/publications/Publ-32660
Publ.-Id: 32660


Timing of the post-LGM retreat of the Iller Piedmont Glacier (Southern Germany) based on in-situ ³⁶Cl exposure dating of glacial erratics

Hildebrandt, D.; Hofmann, F.; Merchel, S.; Rugel, G.; Strößner, K.; Akber, S.; Friedrich, A. M.

The dynamic behavior of glacial retreat following the Last Glacial Maximum (LGM), which is globally diachronous, is poorly understood. Along strike of the northern Alpine margin, multiple lobes of large foreland glaciers left a complex morpho-sedimentary record. While the reconstructed LGM ice extent is laterally constant in the west, it shows significant variations in the central and eastern part. We use these local geologic variations to explore how regional climatic conditions relate to global climate during this period of rapid late Pleistocene climate change. The chronology for this interval has been well-constrained in Switzerland, but radiometric ages have only been reported for a few locations along the Alpine Foreland in Germany. In this study, we employ cosmogenic ³⁶Cl in limestone to constrain the in-situ exposure age of glacial erratics situated on moraine walls of the Iller Piedmont Glacier. We sampled erratic boulders along a transect perpendicular to three moraine ridges previously interpreted to represent the LGM along with two post-LGM retreat stands. Our preliminary raw data show that the sampled lithology provides internally consistent, reproducible, and geologically meaningful dates. We discuss our results taking into account limestone weathering, erosion and local postglacial landscape stabilization, and apply appropriate correction factors to obtain more accurate ages. This exposure age data gives first insights into the spatio-temporal patterns of glacial retreat in the northern Alpine Foreland, which can be used to reconstruct Central European paleoclimate in the late Pleistocene.

Keywords: AMS; LGM; glacier; climate; TCN

  • Poster
    Geokarlsruhe 2021, 19.-24.09.2021, Karlsruhe, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-32659
Publ.-Id: 32659


High-field THz pulses from a GaAs photoconductive emitter for non-linear THz studies

Singh, A.; Li, J.; Pashkin, O.; Rana, R.; Winnerl, S.; Helm, M.; Schneider, H.

This is the raw data related to the publication "High-field THz pulses from a GaAs photoconductive emitter for non-linear THz studies".

  • The file "THzPowerMeasurement.xlsx" is manually noted THz power reading from the locking. It is used for Figs. 2(a&b).
  • The file "005-PCA-60V_100mW.thz" is the THz time-domain data corresponding to Fig2 (c).  
  • The files "017******* to 027**********" are data corresponding to Figs 3(a&b). Plots in Figs. 4(b-d) are also calculated from these data files.
  • The files "003-PCA-1mm.thz", "004-PCA-withoutAperture.thz", and "005-PCA-1point2mm.thz" are data used for THz spot diameter calculation.

Keywords: Terahertz emitter; Photoconductive THz emitter; Nonlinear THz effects

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-05-21
    DOI: 10.14278/rodare.989
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-32657
Publ.-Id: 32657


Rise and fall of laser-intensity effects in spectrally resolved Compton process

Hernandez Acosta, U.; Titov, A.; Kämpfer, B.

The laser intensity dependence of nonlinear Compton scattering is discussed in some detail. For sufficiently hard photons with energy ω', the spectrally resolved differential cross section dσ/dω'|ω'=const, rises from small toward larger laser intensity parameter ξ, reaches a maximum, and falls toward the asymptotic strong-field region. Such a rise and fall of a differential observable is to be contrasted with the monotonously increasing laser intensity dependence of the total probability, which is governed by the soft spectral part. We combine that hard-photon yield from Compton scattering with the seeded Breit–Wheeler pair production in a folding model and obtain a rapidly increasing e+e− pair number at ξ ≲ 4. Laser bandwidth effects are quantified in the weak-field limit of the related trident pair production.

Keywords: non-linear Compton scattering; nonlinear Breit-Wheeler pair production; strong-field QED

Permalink: https://www.hzdr.de/publications/Publ-32656
Publ.-Id: 32656


Data for: Bubble formation from sub-millimeter orifices under variable gas flow conditions

Mohseni, E.; Ziegenhein, T.; Reinecke, S. F.; Hampel, U.

This is the data for the publication ID 32653.

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-05-21
    DOI: 10.14278/rodare.987

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Permalink: https://www.hzdr.de/publications/Publ-32655
Publ.-Id: 32655


Bubble formation from sub-millimeter orifices under variable gas flow conditions

Mohseni, E.; Ziegenhein, T.; Reinecke, S.; Hampel, U.

We provide an experimental investigation on the mechanism of the bubble formation from sub-millimeter orifices under variable gas flow conditions VGFC. The effect of influential parameters including the volumetric gas flow rate Q, the orifice diameter dor, and the volume of the gas reservoir Vc upstream of the orifice are investigated in detail. We found that, by enlarging Vc, q increases. This affects various aspects of bubble formation dynamics such as the bubble base expansion, the apparent contact angle at the three-phase contact point, and the bubble detachment criterion. The effect of Vc is best presented by its dimensionless group, the capacitance number Nc. The minimum Nc from which the influence of the gas reservoir becomes important depends on the orifice size. Moreover, a significant increase in Vc leads to a change in the bubbling regime towards multiple bubble formation.

Keywords: Bubble formation; Sub-millimeter orifice; Gas reservoir; Bubble dynamics

Related publications

Permalink: https://www.hzdr.de/publications/Publ-32653
Publ.-Id: 32653


Research and Metadata Management at HZDR

Knodel, O.

The talk introduces the current status of the research and metadata management at HZDR.

Keywords: Data Management; Rodare; Mediawiki; Heliport

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    Research Data and Metadata Management Workshop Health, 21.05.2021, Heidelberg, Germany

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Permalink: https://www.hzdr.de/publications/Publ-32652
Publ.-Id: 32652


Technetium retention by green rust chloride

Mayordomo, N.; Rodriguez Hernandez, D. M.; Schild, D.; Roßberg, A.; Scheinost, A.; Brendler, V.; Müller, K.

Techntium-99 (99Tc) is one of the most concerning fission products due to its long half-life (2.14∙10⁵ years) and the mobility of the anion pertechnetate (TcO₄⁻). [1] However, Tc migration decreases when Tc(VII) is reduced to Tc(IV). This scavenging step is favored by reductive material, among which Fe(II) minerals have been widely studied due to their versatility, low cost and ubiquity. [2]
Green rust is a Fe(II)-Fe(III) mixed hydroxide that possesses adsorption, anion exchange and reduction capabilities. Its presence is expected in the near- and far-field of a nuclear waste repository because it is an iron corrosion product, and it is also formed in the environment when Fe²⁺ interacts with Fe(III) minerals. [3]
Batch contact studies have been performed under a wide range of conditions, i.e. pH (3-11), Tc concentration (nM-mM), and ionic strength (0-0.1 M). X-ray diffraction, Raman microscopy, X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) provided information on Tc oxidation state and speciation as well as on secondary redox products related to the Tc interaction with green rust. In addition, re-oxidation experiments have been performed during six months.
The results show that green rust removes Tc from solution with efficiencies between 80% (Kd = 8.0∙103 mL/g) and ≈100% (Kd = 9.9∙10⁵ mL/g) for pH > 6.0, regardless on the ionic strength and the Tc concentration. In contrast, Tc removal for pH < 6.0 drops with decreasing pH, and ranges from 80% to 50% (Kd = 2.0∙10³ mL/g), reaching a minimum at pH 3.5. XPS analysis reveals the predominance of Tc(IV) at all evaluated pH values (3.5 to 11.5), supporting that Tc reductive immobilization is the main retention mechanism. Re-oxidation experiments show that Tc is slowly solubilized when time increases.
We thank the German Federal Ministry of Economic Affairs and Energy (BMWi) for funding the VESPA II project (02E11607B).
[1] Meena, A.H.; Arai, Y. Env. Chem Lett (2017), 15, 241–263.
[2] Pearce, C.I. et al. Sci. Total Environ. (2020), 716, 132849.
[3] Usman, M. et al. Chem. Rev. (2018), 118, 3251–3304.

Keywords: Technetium; Reductive immobilization; Sorption; Fe(II)-minerals

  • Lecture (Conference) (Online presentation)
    Goldschmidt 2021, 04.-09.07.2021, Online, Online

Permalink: https://www.hzdr.de/publications/Publ-32650
Publ.-Id: 32650


Scaling of Lift Reversal of Deformed Bubbles in Air-Water Systems

Hayashi, K.; Heßenkemper, H.; Lucas, D.; Legendre, D.; Tomiyama, A.

Scaling of the lift reversal for a deformed bubble in the surface tension-inertial force dominant regime was discussed. Lift data of bubbles in water recently reported in literature were used. The negative lift component was well correlated in terms of the drag coefficient, which, in turn, implies that the vorticity produced at the bubble surface plays a key role in both drag and lift forces as is the case with the viscous force dominant regime. The scaling was confirmed to give good evaluations of the lift coefficients.

Keywords: Lift force; Lift reversal; Negative lift; Shape deformation

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Permalink: https://www.hzdr.de/publications/Publ-32647
Publ.-Id: 32647


Llama, a low level abstraction library for memory access

Gruber, B. M.

This talk presents the current state of LLAMA, the library for Low Level Abstraction of Memory Access.

  • Open Access Logo Lecture (Conference) (Online presentation)
    Compute Accelerator Forum, 12.05.2021, virtual, Switzerland

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Permalink: https://www.hzdr.de/publications/Publ-32643
Publ.-Id: 32643


Stable isotope fractionation of thallium as novel evidence for its geochemical transfer during lead‑zinc smelting activities

Zhou, Y.; He, H.; Wang, J.; Liu, J.; Lippold, H.; Bao, Z.; Wang, L.; Lin, Y.; Fang, F.; Huang, Y.; Jiang, Y.; Xiao, T.; Yuan, W.; Wei, X.; Tsang, D. C. W.

Thallium(Tl) is a highly toxic trace metal. Lead(Pb)-zinc(Zn) smelting, which is a pillar industry in various countries, is regarded as one of the dominant anthropogenic sources of Tl contamination in the environment. In this study, thallium isotope data have been evaluated for raw material and a set of industrial wastes produced at different stages of Pb-Zn smelting in a representative large facility located by the North River, South China, in order to capture Tl isotope signatures of such typical anthropogenic origin for laying the foundation of tracking Tl pollution. Large variations in Tl isotopic compositions of raw Pb-Zn ores and solid smelting wastes produced along the process chain were observed. The ε205Tl value of raw Pb-Zn ores and return fines are −0.87 ± 0.26 and −1.0 ± 0.17, respectively, contrasted by increasingly more negative values for electrostatic precipitator dust (ε205Tl = −2.03 ± 0.14), lime neutralizing slag (ε205Tl = −2.36 ± 0.18), and acid sludge (ε205Tl = −4.62 ± 0.76). The heaviest ε205Tl (1.12 ± 0.51) was found in clinker. These results show that isotopic fractionation occurs during the smelting processes. Obviously, the lighter Tl isotope is enriched in the vapor phase (−3.75 ε205Tl units). Further XPS and STEM-EDS analyses show that Tl isotope fractionation conforms to the Rayleigh fractionation model, and adsorption of 205Tl onto hematite (Fe2O3) may play an important role in the enrichment of the heavier Tl isotope. The findings demonstrate that Tl isotope analysis is a robust tool to aid our understanding of Tl behavior in smelting processes and to provide a basis for source apportionment of Tl contaminations.

Keywords: Tl contamination; Tl isotope; Pb-Zn smelting; Rayleigh fractionation

Permalink: https://www.hzdr.de/publications/Publ-32642
Publ.-Id: 32642


Low Carbon Footprint Recycling of Post-Consumer PET Plastic with a Metagenomic Polyester Hydrolase

Sonnendecker, C.; Oeser, J.; Richter, P. K.; Hille, P.; Zhao, Z.; Fischer, C.; Lippold, H.; Blázquez-Sánchez, P.; Engelberger, F.; Ramírez-Sarmiento, C. A.; Oeser, T.; Lihanova, Y.; Frank, R.; Jahnke, H.-G.; Billig, S.; Abel, B.; Sträter, N.; Matysik, J.; Zimmermann, W.

Our planet is flooded with plastics and the need for sustainable recycling strategies of polymers has become increasingly urgent. Enzyme-based hydrolysis of post-consumer plastic is an emerging strategy for closed-loop recycling of polyethylene terephthalate (PET). The polyester hydrolase PHL7 isolated from a compost metagenome completely hydrolyzed amorphous PET films, releasing 91 mg of terephthalic acid per hour and mg of enzyme. Degradation rates of the PET film of 6.8 µm h-1 were monitored by vertical scanning interferometry. Structural analysis indicated the importance of leucine at position 210 for the extraordinarily high PET-hydrolyzing activity of PHL7. Within 24 h, 0.6 mgenzyme gPET -1 completely degraded post-consumer thermoform PET packaging in an aqueous buffer at 70°C without any energy-intensive pretreatments. Terephthalic acid recovered from the enzymatic hydrolysate was used to synthesize virgin PET, demonstrating the potential of polyester hydrolases as catalysts in sustainable PET recycling processes with a low carbon footprint.

Permalink: https://www.hzdr.de/publications/Publ-32641
Publ.-Id: 32641


Optimization of multi-group energy structures for diffusion analyses of sodium-cooled fast reactors assisted by simulated annealing – Part II: methodology application

Di Nora, V. A.; Fridman, E.; Nikitin, E.; Bilodid, Y.; Mikityuk, K.

Part I of this study introduced a novel methodology for the optimization of energy group structures to be used in diffusion calculations of Sodium Fast Reactors (SFRs). Such a methodology is assisted by either direct or simulated annealing search techniques. The capabilities of the method were preliminarily demonstrated on a single core state of the Superphénix reactor by using the DYN3D nodal diffusion code.
The scope of Part II is the further demonstration of the methodology efficiency through its application to more challenging “real-life” cases. In this respect, a static Superphénix neutronic benchmark comprising 13 different core states and a transient test initiated by an increase of the core inlet temperature at the Phénix reactor are considered.
For both Superphénix and Phénix reactor cores, 2- to 12-group optimal condensed energy group structures are identified using the 24-group structure as a starting point. The obtained optimal structures are thus employed in DYN3D and compared to the reference 24-group DYN3D solutions.
The outcomes show that also for a broader range of core configurations and under transient conditions the optimal energy group structures allow for significant acceleration of the DYN3D performance with practically negligible degradation of the solution accuracy.

Keywords: Serpent; SFR; energy structure optimization; simulated annealing

Related publications

Permalink: https://www.hzdr.de/publications/Publ-32640
Publ.-Id: 32640


Inductive System for Magnesium Level Detection in a Titanium Reduction Reactor

Krauter, N.; Eckert, S.; Gundrum, T.; Stefani, F.; Wondrak, T.; Khalilov, R.; Dimov, I.; Frick, P.

The determination of the magnesium level in a titanium reduction retort by inductive methods
is often hampered by the formation of titanium sponge rings which disturb the propagation of
electromagnetic signals between excitation and receiver coils. We present a new method for the
reliable identification of the magnesium level which explicitly takes into account the presence of sponge rings with unknown geometry and conductivity. The resulting inverse problem is solved by a look-up-table method, based on the solution of the inductive forward problems for several tens thousands of parameter combinations. The feasibility of that method is demonstrated by performing numerical simulations and measurements on a model experiment. This method is not limited to the production of titanium but can also be applied to other applications in metal production and processing.

Keywords: Kroll Process; Numerical Simulation; Inductive Measurements; Titanium; Level Detection

  • Contribution to proceedings
    Electromagnetic Processing of Materials 2021, 13.-17.06.2021, Riga, Lettland
    Proceedings of the 10th international conference on Electromagnetic Processing of Materials
  • Lecture (Conference) (Online presentation)
    Electromagnetic Processing of Materials 2021, 13.-17.06.2021, Riga, Lettland
  • Lecture (Conference) (Online presentation)
    4th Russian Conference on Magnetohydrodynamics, 20.-22.09.2021, Perm, Russland

Permalink: https://www.hzdr.de/publications/Publ-32638
Publ.-Id: 32638


H2pyhox - Octadentate Bis(pyridyloxine)

Southcott, L.; Wang, X.; Choudhary, N.; Wharton, L.; Patrick, B.; Yang, H.; Zarschler, K.; Kubeil, M.; Stephan, H.; Jaraquemada-Pelaez, M. D. G.; Orvig, C.

A new versatile chelating ligand for intermediate size and softness radiometals [64Cu]Cu2+ and [111In]In3+, H2pyhox, was synthesized by introducing
pyridine as a new donor moiety to complement 8-hydroxyquinoline on an ethylenediamine backbone. The combination of pyridine
and oxine as donor sets was explored through structural analysis, and crystals of the three metal complexes with Cu2+, La3+ and In3+ demonstrate how the ligand adapts to accommodate metal ions of different sizes and charge. Exhaustive in-batch UV solution studies characterized the protonation constants of the free ligand as well as the formation constants of the metal complexes with Cu2+, In3+ and La3+. Preliminary concentration dependent radiolabeling studies with [111In]In3+ and [64Cu]Cu2+ show the robustness of H2pyhox to successfully coordinate both radiometals under mild conditions (< 15 min, room temperature, pH 6). H2pyhox is the first oxinate ligand to successfully radiolabel [225Ac]Ac3+, albeit only at high concentrations (0.1 – 1 mM) with gentle heating to 37℃. Whole serum, protein and ligand challenge assays further demonstrate the kinetic inertness of the radiometal-ligand complexes, confirming H2pyhox to be a promising versatile radiopharmaceutical chelator.

Permalink: https://www.hzdr.de/publications/Publ-32635
Publ.-Id: 32635


Evolution of the magnetic hyperfine field profiles in ion-irradiated Fe60Al40 film measured by nuclear resonant reflectivity

Andreeva, M.; Smekhova, A.; Baulin, R.; Repchenko, Y.; Bali, R.; Schmitz-Antoniak, C.; Wende, H.; Sergueev, I.; Schlage, K.; Wille, H. C.

Nuclear resonant reflectivity (NRR) from an Fe60Al40 film was measured using synchrotron radiation at several grazing angles near the critical angle of the total external reflection. By laterally resolved measurements after 20 keV Ne+ ion irradiation with gradually varied fluences of 0 - 3.0 x 10^14 ions/cm2, the progressive creation of the ferromagnetic A2 phase with increasing ion fluence was confirmed. The observed depth-selectivity of the method has been explained by application of the standing wave approach. From the time spectra of the nuclear resonant scattering in forward or diffraction directions the depth-profiles for different hyperfine fields were extracted. The results evidence that the highest magnetic hyperfine fields (~ 18 % 23 T) are initially created at the center part of the film and partially at the bottom interface with SiO2 substrate. The evolution of the ferromagnetic onset, commencing at a fixed depth within the film and propagating towards the interfaces has been directly observed. At higher fluence (3.01014 ions/cm2) the depth distribution of the ferromagnetic fractions became more homogeneous across the film depth in accordance with previous results.

Keywords: Magnetic patterning; ion irradiation; x-ray reflectivity; hyperfine interactions; nuclear resonant scattering; magnetic depth-profiles; Mössbauer spectroscopy

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Permalink: https://www.hzdr.de/publications/Publ-32632
Publ.-Id: 32632


HELIPORT: A Portable Platform for FAIR {Workflow | Metadata | Scientific Project Lifecycle} Management and Everything

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

Modern scientific collaborations and projects (MSCPs) employ various processing stages, starting with the proposal submission, continuing with data acquisition and concluding with final publications. The realization of such MSCPs poses a huge challenge due to (1) the complexity and diversity of the tools, (2) the heterogeneity of various involved computing and experimental platforms, (3) flexibility of analysis targets towards data acquisition and (4) data throughput. Another challenge for MSCPs is to provide additional metadata according to the FAIR principles for all processing stages for internal and external use. Consequently, the demand for a system, that assists the scientist in all project stages and archives all processes on the basis of metadata standards like DataCite to make really everything transparent, understandable and citable, has risen considerably. The aim of this project is the development of the HELmholtz ScIentific Project WORkflow PlaTform (HELIPORT), which ensures data provenance by accommodating the complete life cycle of a scientific project and linking all employed programs and systems. The modular structure of HELIPORT enables the deployment of the core applications to different Helmholtz centers (HZs) and can be adapted to center-specific needs simply by adding or replacing individual components. HELIPORT is based on modern web technologies and can be used on different platforms.

Keywords: Data Management; Metadata; Scientific Project; FAIR; Data provenance; Related Identifier; Datasets; Digital Objects

  • Open Access Logo Contribution to proceedings
    4th International Workshop on Practical Reproducible Evaluation of Computer Systems (P-RECS ’21), 21.-25.06.2021, Stockholm, Sweden
    Proceedings of the 4th International Workshop on Practical Reproducible Evaluation of Computer Systems (P-RECS ’21), New York, NY, USA: ACM, 978-1-4503-8395-0/21/06, 9-14
    DOI: 10.1145/3456287.3465477

Permalink: https://www.hzdr.de/publications/Publ-32631
Publ.-Id: 32631


GPU-based computation of coalescence and breakup models for polydisperse bubbly flows

Petelin, G.; Kelling, J.; Lehnigk, R.; Papa, G.; Schlegel, F.

Polydisperse bubbly flows appear in many industrial applications and are particularly relevant for nuclear and process engineering. A popular approach for their simulation is the two-fluid model, which requires information about the bubble size. An associated challenge is to incorporate the effects of coalescence and breakup on the size distribution, which can be tracked by a population balance equation. It can be solved by the method of classes, which splits the bubble population into a finite number of size groups. However, this technique is expensive because the source term assembly involves the computation of coalescence and breakup frequencies between all bubble size pairs. This work focuses on improving the performance of the class method implementation within the OpenFOAM Foundation release (www.openfoam.org), an open source computational fluid dynamics software that allows for domain decomposition and parallel execution on multiple central processing units. Here, the parallel computation of the coalescence and breakup frequencies is shifted to graphics processing units using the Nvidia CUDA framework. Calculations are done asynchronously with overlapping data transfers, treating size pairs as independent units of work that are computed in parallel. The coalescence and breakup frequency computation on graphics processing units leads to a significant speedup compared to the pre-existing implementation. The improvement is demonstrated for a co-current two-phase flow in a vertical pipe. Both the source code and the case setup are made publicly available.

  • Lecture (Conference)
    30th International Conference Nuclear Energy for New Europe, 06.-09.09.2021, Bled, Slovenien

Permalink: https://www.hzdr.de/publications/Publ-32629
Publ.-Id: 32629


Microscopic characterization of un-irradiated and irradiated steel shielding material of a nuclear power plant

Yassin, G.; Barkleit, A.; Brendler, V.

Nuclear power plants (NPPs) have been considered an important energy source in Europe over a long time. However, in Germany the government decided that NPPs must terminate their operation end of 2022 at the latest, due to their possible threats on humans and the environment. The question arises, how much the long term irradiation of an NPP poses safety risks, in particular, in the reactor pressure vessel (RPV), which is the main shielding barrier of the radioactive fuel. For this purpose, the microstructural features, the composition, and the radioactive inventory of the steel shielding material in the RPV are investigated.

Related publications

  • Contribution to HZDR-Annual report
    Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-113 Mai 2020, 77-78
    ISSN: 2191-8708, eISSN: 2191-8716

Permalink: https://www.hzdr.de/publications/Publ-32628
Publ.-Id: 32628


Coexistence of fluorescent Escherichia coli strains in millifluidic droplet reactors

Zhao, X.; Illing, R.; Ruelens, P.; Bachmann, M.; Cuniberti, G.; de Visser, J. A. G. M.; Baraban, L.

Understanding competition and cooperation within microbiota is of high fundamental and clinical importance, helping to comprehend species' evolution and biodiversity. We co-encapsulated and cultured two isogenic Escherichia coli strains expressing blue (BFP) and yellow (YFP) fluorescent proteins into numerous emulsion droplets and quantified their growth by employing fluorescence measurements. To characterize and compare the bacterial growth kinetics and behavior in mono and co-culture, we compared the experimental observations with predictions from a simple growth model. Varying the initial ratio (R0) of both cell types injected, we observed a broad landscape from competition to cooperation between both strains in their confined microenvironments depending on start frequency: from a nearly symmetric situation at R0 = 1, up to the domination of one subpopulation when R0 ≫ 1 (or R0 ≪ 1). Due to competition between the strains, their doubling times and final biomass ratios (R1) continuously deviate from the monoculture behavior. The correlation map of the two strains' doubling times reveals that the R0 is one of the critical parameters affecting the competitive interaction between isogenic bacterial strains. Thanks to this strategy, different species of bacteria can be monitored simultaneously in real-time. Further advantages include high statistical output, unaffected bacteria growth, and long-time measurements in a well-mixed environment. We expect that the millifluidic droplet-based reactor can be utilized for practical clinical applications, such as bacterial antibiotic resistance and enzyme reaction kinetics studies.

Keywords: droplets; microbiology; bacterial coexistance

Permalink: https://www.hzdr.de/publications/Publ-32626
Publ.-Id: 32626


Sensitivity of PS/CoPd Janus particles to an external magnetic field

Eichler-Volf, A.; Alsaadawi, Y.; Vazquez Luna, F.; Khan, Q. A.; Stierle, S.; Xu, C.; Heigl, M.; Fekri, Z.; Zhou, S.; Zahn, P.; Albrecht, M.; Steinhart, M.; Erbe, A.

The dual nature of Janus particles confers fascinating properties such as a response to multiple stimuli. In this communication, we systematically study the sensitivity to a uniform external magnetic field of isolated Janus rod-shaped and spherical particles in water confined to two dimensions. The Janus asymmetry of the particles is given by magnetic [Co(0.28 nm)/Pd(0.90 nm)]8 multilayer films deposited onto monodisperse polystyrene (PS) nanorods and microspheres, respectively. It is shown that the particles dispersed in water respond to weak magnetic field applied in in-plane direction. Here we demonstrate that a precise control of the in-plane particle orientation can be obtained for magnetic field strengths higher than 0.1 mT for microspheres and 0.4 mT for nanorods.

Related publications

Permalink: https://www.hzdr.de/publications/Publ-32624
Publ.-Id: 32624


Magnetically Induced Aggregation of Iron Oxide Nanoparticles for Carrier Flotation Strategies

Schwaminger, S. P.; Schwarzenberger, K.; Gatzemeier, J.; Lei, Z.; Eckert, K.

On the nanoscale, iron oxides can be used for multiple applications ranging from medical treatment to biotechnology. We aimed to utilize the specific properties of these nanoparticles for new process concepts in flotation. Magnetic nanoparticles were synthesized by alkaline coprecipitation, leading to a primary particle size of 9 nm, and coated with oleate. The nanomaterial was characterized for its superparamagnetism and its colloidal stability at different ionic strengths, with and without an external magnetic field. The nanomaterial was used for model experiments on magnetic carrier flotation of microplastic particles, based on magnetically induced heteroagglomeration. We were able to demonstrate the magnetically induced aggregation of the nanoparticles which allows for new flotation strategies. Since the nanomaterial has zero remanent magnetization, the agglomeration is reversible which facilitates the process control. Magnetic carrier flotation based on iron oxide nanoparticles can pave the way to promising new recycling processes for microplastic wastes.

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  • Secondary publication expected from 22.04.2022

Permalink: https://www.hzdr.de/publications/Publ-32623
Publ.-Id: 32623


Pyrrol-Based Ligands as Salen Relatives: Complex Synthesis, Characterization and Comparison

Köhler, L.; Patzschke, M.; März, J.; Schmidt, M.; Stumpf, T.

Schiff bases like the mixed N, O donor ligands of the salen (Bis(salicyliden)ethylendiamin) family are frequently chosen systems for complexation studies. Advantageous is their ability to stabilize a large number of metals including actinides, as well as their tuneable electronical and sterical properties.1–4 Pyrrol-based ligands are salen’s structural relatives, but only exhibit N-donor functionalities. This provides the possibility to investigate and compare the binding situation between early actinides and N atoms in different environments.
In this study a complex series from Th to Pu with the pyrrol-based ligands 1,2-ethylenediamine-N,N’-bis(1H-pyrrol-2-yl)methylene (pyrenH2) L¹ H₂ and 1,2-benzenediamine-N,N’-bis(1H-pyrrol-2-yl)methylene (pyrophenH2) L² H₂ was synthesized. Characterization in solution (NMR) and solid state (SC-XRD) in combination with quantum chemical calculations reveal the different binding situations to the different N donors at the electronic level, which leads to unique paramagnetic behavior in solution.

1 B. E. Klamm et al., Chem. Commun., 2018, 54, 8634–8636.
2 A. N. Dame et al., Eur. J. Inorg. Chem., 2015, 2015, 2996–3005.
3 B. E. Klamm et al., Inorg. Chem., 2018, 57, 15389–15398.
4 T. Radoske et al., Chem. – Eur. J., 2020, 26, 16853–16859.

Keywords: actinides; N donor ligands; SC-XRD

  • Lecture (Conference) (Online presentation)
    ACS-Spring Meeting, 12.04.2021, USA, USA

Permalink: https://www.hzdr.de/publications/Publ-32622
Publ.-Id: 32622


Photoluminescence Lineshapes for Defect Centers in Silicon Carbide from First-Principles Calculations

Hashemi, A.; LinderäLv, C.; Krasheninnikov, A.; Ala-Nissilä, T.; Erhart, P.; Komsa, H.-P.

Silicon carbide with optically and magnetically active point defects offers unique opportunities for quantum technology applications. Since interaction with these defects commonly happens through optical excitation and deexcitation, a complete understanding of their light-matter interaction in general and optical signatures in particular is crucial. Here, we employ quantum mechanical density functional theory calculations to investigate the photoluminescence line shapes of selected, experimentally observed color centers (including single vacan- cies, double vacancies, and vacancy-impurity pairs) in 4H-SiC. The analysis of zero-phonon lines as well as Huang-Rhys and Debye-Waller factors is accompanied by a detailed study of the underlying lattice vibrations. We show that the defect line shapes are governed by strong coupling to bulk phonons at lower energies and localized vibrational modes at higher energies. Generally, good agreement with the available experimental data is obtained, and thus we expect our theoretical work to be beneficial for the identification of defect signatures in the photoluminescence spectra and thereby advance the research in quantum photonics and quantum information processing.

Keywords: SiC; photoluminecsence; color centers; defects

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Permalink: https://www.hzdr.de/publications/Publ-32621
Publ.-Id: 32621


Effect of temperature and strain rate on the deformation behavior of Ti5321 during hot-compression

Gu, B.; Chekhonin, P.; Xin, S. W.; Liu, G. Q.; Ma, C. L.; Zhou, L.; Skrotzki, W.

The effect of deformation temperature and strain rate (collectively described by the Zener-Hollomon parameter Z) on the deformation mechanism and texture formation of the metastable β-titanium alloy Ti5321 across the β-transus temperature during hot-compression was investigated by electron backscatter diffraction. In the β-phase field, it is found that the deformation behavior and texture formation varies depending on Z. With decreasing Z dynamic recovery and dynamic recrystallization become more and more important. The activation energy for steady state deformation is 240 kJ/mol and 370 kJ/mol in the β- and (α + β)-phase field, respectively. The texture developed is a <100> <111> double-fiber with < 100 > dominating at all deformation conditions. The <111> fiber gets more prominent with increasing Z suggesting that it is mainly related to deformation. Flow softening behavior of Ti5321 is associated with dynamic globularization of the α-phase and promotion of β-grain formation by continuous dynamic recrystallization.

Keywords: Metastable β-titanium alloy; EBSD; Microstructure; Texture; Dynamic recrystallization; Deformation mechanism

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  • Secondary publication expected from 16.04.2022

Permalink: https://www.hzdr.de/publications/Publ-32620
Publ.-Id: 32620


HELIPORT: A Potential Platform for Running Digital Twins FAIRly

Knodel, O.

This presentation introduces the HELIPORT project, which aims at developing a platform which accommodates the complete life cycle of a scientific project and links all corresponding programs, systems and workflows to create a more FAIR and comprehensible project description. Heliport is linked with our local Handle-Server and generates uniform PIDs from and for various systems and services. With the integration of the Handle system Heliport can support digital twins.

Keywords: Data management; Digital twins; Handles

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    LEAPS Integrated Platform Workshop, Digital Twinning Session, 11.-12.05.2021, Villigen, Schweiz

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Permalink: https://www.hzdr.de/publications/Publ-32619
Publ.-Id: 32619


Multistate current-induced magnetization switching in Au/Fe/MgO(001) epitaxial heterostructures

Gospodarič, P.; Młyńczak, E.; Soldatov, I.; Kakay, A.; Bürgler, D. E.; Plucinski, L.; Schäfer, R.; Faßbender, J.; Schneider, C. M.

Magnetization switching using in-plane charge current recently has been widely investigated in heavy metal/ferromagnet bilayers with the switching mechanism usually attributed to the action of the spin-orbit coupling. Here we study in-plane current induced magnetization switching in model epitaxial bilayers that consist of Au(001) and Fe(001) grown on MgO(001). We use the planar Hall effect combined with magnetooptical Kerr effect (MOKE) microscopy to investigate magnetic properties of the bilayers and current-induced switching. We show that a current density beyond 1.4×10^7 A/cm can be employed for reproducible electrical switching of the magnetization between multiple stable states that correspond to different arrangements of magnetic domains with magnetization direction along one of the in-plane easy magnetization axes of the Fe(001) film. Lower current densities result in stable intermediate transversal resistances which are interpreted based on MOKE-microscopy investigations as resulting from the current-induced magnetic domain structure that is formed in the area of the Hall cross. We find that the physical mechanism of the current-induced magnetization switching of the Au/Fe/MgO(001) system at room temperature can be fully explained by the Oersted field, which is generated by the charge current flowing mostly through the Au layer.

Permalink: https://www.hzdr.de/publications/Publ-32616
Publ.-Id: 32616


High-field THz pulses from GaAs photoconductive emitter for non-linear THz studies

Singh, A.; Li, J.; Pashkin, O.; Rana, R.; Winnerl, S.; Helm, M.; Schneider, H.

We report the emission of high-field terahertz pulses from a GaAs large-area photoconductive emitter pumped with a Ti:Sapphire amplifier laser system at 800 nm wavelength and 1 kHz repetition rate. The maximum estimated terahertz electric field at the focus is ≳ 230 kV/cm. We also demonstrate the capability of the terahertz field to cause a non-linear effect, which usually requires high-field terahertz pulses generated through optical rectification or an air plasma. A significant drop in the optical conductivity of optically pumped GaAs due to Γ-L inter-valley scattering of free electrons caused by the strong THz field is found.

Keywords: Terahertz sources; Nonlinear THz; Photoconductive emitter

Related publications

Permalink: https://www.hzdr.de/publications/Publ-32614
Publ.-Id: 32614


Advanced Git Usage

Erxleben, F.

A talk and demo session on various topics of advanced usage regarding the version control system Git.

Keywords: Git; Talk

  • Open Access Logo Lecture (others) (Online presentation)
    PCD Data Science Basics, 11.05.2021, Hamburg, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-32613
Publ.-Id: 32613


Stratigraphy, depositional setting, and shrimp u-pb geochronology of the banded iron formation–bearing bailadila group in the bacheli iron ore mining district, bastar craton, india

Mukhopadhyay, J.; Armstrong, R. A.; Gutzmer, J.; de Kock, M.; Beukes, N. J.

The Bailadila Group of the Bastar Craton, India, is host to a 200-m-thick banded iron formation (BIF). We document the lithostratigraphic context for the BIF, informally referred to as the Bose iron formation, and provide radiometric constraints for its depositional age. Field evidence illustrates that the BIF was deposited on an inner-shelf succession with a quartz arenite that grades upward into the BIF through storm-dominated offshore shelf deposits. The quartz arenite to BIF transition records a relative sea level rise from transgressive to highstand systems tract when the BIFs were deposited in a starved outer continental shelf. U-Pb SHRIMP analyses of zircons from the basement of the Bailadila Group yielded mostly highly discordant U-Pb SHRIMP ages. However, the ages fall on well-defined discordia lines from which concordia intercept ages could be determined. These ages, in combination with the ages of a few zircons that are less than 6% discordant, indicate that the granitoid basement crystallized at 3500–3550 Ma. The maximum depositional age of the Bailadila Group is constrained from the weighted mean207 Pb/206 Pb SHRIMP age of 2725 5 57 Ma from detrital zircons from the basal arenites. A well-constrained weighted mean207 Pb/206 Pb SHRIMP age of 2733 5 53 Ma for zircons from a unit that unconformably overlies the Bailadila Group is within error of that age. Stratigraphic relationships suggest that the Bailadila succession is unconformably overlain by the ~2.5 Ga Kotri and Dongargarh Supergroups. The depositional age of the Bailadila Group is well constrained between ~2.7 and 2.5 Ga. In contrast to most other Archean Algoma-type iron formations of peninsular India, which are closely related to volcanic rocks in greenstone belts, the Bose iron formation is associated with siliciclastic shelf succession. It thus is considered a Superior-type iron formation that represents the oldest known one of its kind in India.

Keywords: banded iron formation; Bastar Cartoon; stratigraphy; age

  • Journal of Geology 129(2021)1
    Online First (2021) DOI: 10.1086/713683

Permalink: https://www.hzdr.de/publications/Publ-32611
Publ.-Id: 32611


Towards standalone attitude estimation for instrumented flow followers

Buntkiel, L.; Reinecke, S.; Hampel, U.

A concept for 3D-motion tracking of instrumented flow-following sensor particles, equipped with a gyroscope, accelerometer, magnetometer and pressure sensor, has been developed. Consisting of an error state Kalman filter (ESKF) the algorithm can track the attitude of the sensor particle in relation to a reference coordinate system. In this short paper we investigated if the estimated attitude returns to the reference trajectory after experiencing motion similar to a motion that is expected to be found in the multidisperse fluid flows of a biogas fermenter or a waste water treatment basin. Results show the feasibility of the proposed method. However, the strategy of the measurement update in the ESKF needs improvement.

Keywords: error state kalman filter; motion tracking; fluid dynamics; sensor particle; soft sensor

  • Open Access Logo Contribution to proceedings
    Sensor and Measurement Science International 2021, 03.-06.05.2021, Online, Deutschland
    SMSI 2021 - Sensors and Instrumentation, Wunstorf: AMA Service GmbH, 978-3-9819376-4-0, 141-142
    DOI: 10.5162/SMSI2021/B6.3

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Permalink: https://www.hzdr.de/publications/Publ-32610
Publ.-Id: 32610


Sustainable Development Goal Conflicts in Re-Mining activities

Büttner, P.; Gutzmer, J.; Engelhardt, J.; Martin, M.

The Davidschacht tailings storage facility (TSF), operated from 1944 to 1964, represents one of the largest tailings dams in the historic Freiberg mining district. It contains a volume of 760,000 m³ of sulfidic flotation tailings, residues of former base metal and silver ore beneficiation. The tailings material still contains elevated concentrations of valuable elements such as zinc (0.4 wt.% on average), lead (0.2 wt.%) and copper (0.05 wt.%) as well as indium (10 ppm). The material has thus become the focus of efforts to enable eventual re-mining and recovery of valuable metals. However, such efforts have to take into account a number of important interests of the public. The first of these is the fact that the unrehabilitated tailings pose a significant risk to the environment. Cd (44 ppm on average) and As (0.6 wt.%) concentrations are particularly high – and have a marked influence on the adjacent water bodies, such as the Freiberg Mulde river. Curbing this influence has been the subject of multiple remediation studies, but pressure to act has risen recently due to increasing regulatory demands on the quality of surface water (EU Water Framework Directive of 2000). This is, in principle, very much in favour of re-mining the tailings in an effort to remove also hazardous components. Counteracting this reclamation scenario is the fact that the TSF is part of the UNESCO World Heritage Site “Erzgebirge / Krusne Hory” that was awarded in 2019. Another restriction pertains to the highly protected status of individual species (esp. sand lizard) settling on the TSF surface. This constellation obviously provides ample space for discussion as to how to deal with the tailings material contained in the Davidschacht TSF in future. Different sustainable development goals (SDG) have to be weighed against each other in order to find a holistic and sustainable. Airlift reactor-based bioleaching has been considered as an opportunity to maximize the sustainability of re-mining activities on the Davidschacht TSF. This innovative approach – and its circumstantial limitations – are documented in this contribution.

Keywords: Re-Mining; recomine; Tailing; Davidschacht; HIF; Resource Technology; Freiberg; Sustainable Development Goals; SDG; Bioleaching

Permalink: https://www.hzdr.de/publications/Publ-32609
Publ.-Id: 32609


Pathophysiological Changes in the Enteric Nervous System of Rotenone-Exposed Mice as Early Radiological Markers for Parkinson's Disease

Schaffernicht, G.; Shang, Q.; Stievenard, A.; Bötzel, K.; Dening, Y.; Kempe, R.; Toussaint, M.; Gündel, D.; Kranz, M.; Reichmann, H.; Vanbesien-Mailliot, C.; Brust, P.; Dieterich, M.; Funk, R. H. W.; Ravens, U.; Pan-Montojo, F.

Parkinson's disease (PD) is known to involve the peripheral nervous system (PNS) and the enteric nervous system (ENS). Functional changes in PNS and ENS appear early in the course of the disease and are responsible for some of the non-motor symptoms observed in PD patients like constipation, that can precede the appearance of motor symptoms by years. Here we analyzed the effect of the pesticide rotenone, a mitochondrial Complex I inhibitor, on the function and neuronal composition of the ENS by measuring intestinal contractility in a tissue bath and by analyzing related protein expression. Our results show that rotenone changes the normal physiological response of the intestine to carbachol, dopamine and electric field stimulation (EFS). Changes in the reaction to EFS seem to be related to the reduction in the cholinergic input but also related to the noradrenergic input, as suggested by the non-adrenergic non-cholinergic (NANC) reaction to the EFS in rotenone-exposed mice. The magnitude and direction of these alterations varies between intestinal regions and exposure times and is associated with an early up-regulation of dopaminergic, cholinergic and adrenergic receptors and an irregular reduction in the amount of enteric neurons in rotenone-exposed mice. The early appearance of these alterations, that start occurring before the substantia nigra is affected in this mouse model, suggests that these alterations could be also observed in patients before the onset of motor symptoms and makes them ideal potential candidates to be used as radiological markers for the detection of Parkinson's disease in its early stages.

Keywords: Parkinson's disease; enteric nervous system; non-motor symptoms; pathophysiology; radiological marker

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Permalink: https://www.hzdr.de/publications/Publ-32608
Publ.-Id: 32608


Half-Auxeticity and Anisotropic Transport in Pd Decorated Two-Dimensional Boron Sheets

Ma, F.; Jiao, Y.; Wu, W.; Liu, Y.; Yang, S. A.; Heine, T.

Upon strain, most materials shrink normal to the direction of applied strain. Similarly, if a material is compressed, it will expand in the direction orthogonal to the pressure. Few materials, those of negative Poisson ratio, show the opposite behavior. Here, we show an unprecedented feature, a material that expands normal to the direction of stress, regardless if it is strained or compressed. Such behavior, namely, half-auxeticity, is demonstrated for a borophene sheet stabilized by decorating Pd atoms. We explore Pd-decorated borophene, identify three stable phases of which one has this peculiar property of half auxeticity. After carefully analyzing stability and mechanical and electronic properties we explore the origin of this very uncommon behavior and identify it as a structural feature that may also be employed to design further 2D nanomaterials.

Keywords: two-dimensional materials; auxetic materials; borophene; buckling structure; first-principle calculation

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  • Secondary publication expected from 03.03.2022

Permalink: https://www.hzdr.de/publications/Publ-32607
Publ.-Id: 32607


Curvature-driven homogeneous Dzyaloshinskii-Moriya interaction and emergent weak ferromagnetism in anisotropic antiferromagnetic spin chains

Pylypovskyi, O.; Borysenko, Y. A.; Faßbender, J.; Sheka, D.; Makarov, D.

Chiral antiferromagnets are currently considered for a broad range of applications in spintronics, spin-orbitronics, and magnonics. In contrast to the established approach relying on materials screening, the anisotropic and chiral responses of low-dimensional antiferromagnets can be tailored relying on the geometrical curvature. Here, we consider an achiral, anisotropic antiferromagnetic spin chain and demonstrate that these systems possess geometry-driven effects stemming not only from the exchange interaction but also from the anisotropy. Peculiarly, the anisotropy-driven effects are complementary to the curvature effects stemming from the exchange interaction and rather strong as they are linear in curvature. These effects are responsible for the tilt of the equilibrium direction of vector order parameters and the appearance of the homogeneous Dzyaloshinskii–Moriya interaction. The latter is a source of the geometry-driven weak ferromagnetism emerging in curvilinear antiferromagnetic spin chains. Our findings provide a deeper fundamental insight into the physics of curvilinear antiferromagnets beyond the σ-model and offer an additional degree of freedom in the design of spintronic and magnonic devices.

Keywords: antiferromagnetism; curvilinear magnetism; Dzyaloshinskii-Moriya interaction; anisotropy

Permalink: https://www.hzdr.de/publications/Publ-32606
Publ.-Id: 32606


Diffusion of In Atoms in SiO2 Films Implanted with As+ Ions

Tyschenko, I. E.; Voelskow, M.; Si, Z.; Popov, V. P.

The diffusion of indium atoms in silicon-dioxide films previously implanted with arsenic ions with different energies is studied in relation to the temperature of postimplantation annealing. It is established that the diffusion properties of indium depend on the presence of arsenic atoms in the film and their energy. An increase in the As content in the region of the average projective range of In+ ions prevents the diffusion of In towards the SiO2 film surface at high annealing temperatures and stimulates the diffusion of In deep into the film in the form of a monovalent interstitial site. The experimentally observed effects are interpreted on the assumption of the formation of In–As pairs in neighboring substitutional positions in the SiO2 matrix.

Permalink: https://www.hzdr.de/publications/Publ-32605
Publ.-Id: 32605


Spin polarization and magnetotransport properties of systematically disordered Fe60Al40 thin films

Borisov, K.; Ehrler, J.; Fowley, C.; Eggert, B.; Wende, H.; Cornelius, S.; Potzger, K.; Lindner, J.; Faßbender, J.; Bali, R.; Stamenov, P.

We investigate the evolution of spin polarization, spontaneous Hall angle (SHA), saturation magnetization and Curie temperature of B2-ordered Fe60Al40 thin films under varying antisite disorder, induced by Ne+-ion irradiation. The spin polarization increases monotonically as a function of ion fluence. A relatively high polarization of 46 % and the SHA of 3.1 % are achieved on 40 nm thick films irradiated with 2 ⋅ 1016 ions/cm2 at 30 keV. An interesting divergence in the trends of the magnetization and SHA is observed for low disorder concentrations. The high spin polarization and its broad tunability range make ion-irradiated Fe60Al40 a promising material for application in spin electronic devices.

Keywords: Spin polarization; Iron-Aluminium; Spintronics; Anomalous Hall Effect; Topological Hall effect; Irradiation effects; Thin films; Magnetometry; Andreev reflection

  • Physical Review B (2021)

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-32604
Publ.-Id: 32604


Statistical position reconstruction for RPC-based thermal neutron detectors

Morozov, A.; Margato, L. M. S.; Solovov, V.; Blanco, A.; Saraiva, J.; Wilpert, T.; Zeitelhack, K.; Roemer, K.; Hall-Wilton, R.

Multilayer position-sensitive 10B-RPC thermal neutron detectors offer an attractive combination of
sub-millimeter spatial resolution and high (>50%) detection efficiency. Here we describe a new
position reconstruction method based on statistical approach. Using experimental data, we compare
performance of this method with that of the centroid reconstruction. Both methods results in a
similar image quality and spatial resolution. However, the statistical method allows to improve the
image quality at the detector periphery, offers more flexible (and more easily configurable) event
filtering and allows to develop automatic quality monitoring procedures for early detection of
situations when a change in the detector operation conditions starts to affect reconstruction quality.

Keywords: RPC; spatial resolution; neutron detection

Permalink: https://www.hzdr.de/publications/Publ-32602
Publ.-Id: 32602


Software: Method for real-time controlled tissue theranostics using a single adaptable laser source

Podlipec, R.

Software support for real-time quantification of the treatment effect on the targeted tissue induced by a pulsed laser. Model functions used to quantify laser treatment effect are based on the calculated descriptor values from FLIM (Fluorescence lifetime imaging microscopy) and AF (autofluorescence) diagnostics images done on human retinal tissue using SPC Image software (B&H).

Related publications

  • Software in the HZDR data repository RODARE
    Publication date: 2021-05-03
    DOI: 10.14278/rodare.971
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-32601
Publ.-Id: 32601


ExPaNDS periodic progress report, September 2019 to February 2021

Servan, S.; Konrad, U.

This document presents the progress of the ExPaNDS (European Open Science Cloud Photon and Neutron Services) project after i ts first 18 months of activities, spanning from September 2019 to February 2021. It reproduces the explanation of the work carried out by the ExPaNDS partners as provided to the European Commission in the first periodic report of the project.

Keywords: EOSC; European Open Science Cloud; Photon Science; Neutron Science; Big Data; Information Technology; Forschungsdaten; Reasearch Data

Permalink: https://www.hzdr.de/publications/Publ-32600
Publ.-Id: 32600


Dataset: Method for real-time controlled tissue theranostics using a single adaptable laser source

Podlipec, R.

Raw data of theranostics laser parameters and calculated descriptor values from FLIM (Fluorescence lifetime imaging microscopy) and AF (autofluorescence) retinal diagnostics for real-time quantification of the treatment effect.

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-05-03
    DOI: 10.14278/rodare.969
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-32599
Publ.-Id: 32599


IV-data for Complex Metal Nanostructures with Programmable Shapes from Simple DNA Building Blocks

Jain, A.; Bayrak, T.; Erbe, A.

IV-curves measured on self-organized Au nanogaps. HSQ-wires are 10 nm gaps without DNA molecules, to characterise the insulating properties of HSQ resist. Au_nanowire are measurements of continuous Au nanowires. The temperature dependent measurements characterize self-organised Au contacts to DNA ensembles with 10 nm length

Keywords: Nanoelectronics; Self-Organisation; DNA Origami

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-05-03
    DOI: 10.14278/rodare.967

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Permalink: https://www.hzdr.de/publications/Publ-32598
Publ.-Id: 32598


Method for controlled tissue theranostics using a single tunable laser source

Podlipec, R.; Mur, J.; Petelin, J.; Štrancar, J.; Petkovšek, R.

Tissue diseases and related disorders need to be first recognized using diagnostic methods and then later treated by therapeutic methods–a joint procedure called theranostics. One of the main challenges in the field of retinal therapies remains in the success of the treatment, typically improving the local metabolism, by sparing the surrounding tissue and with the immediate information of the laser effect. In our study, we present a concept for real-time controlled tissue theranostics on a proof-of-concept study capable of using a single tunable ps
laser source (in terms of irradiance, fluence, and repetition rate), done on ex-vivo human retinal pigment epithelium. We have found autofluorescence intensity and lifetime imaging diagnostics very promising for the recognition and quantification of laser effects ranging from selective non-destructive molecular tissue modification to complete tissue ablation. The main novelty of our work presents the developed algorithm for optimized theranostics based on the model function used to quantify laser-induced tissue changes through the diagnostics
descriptors, fluorescence lifetime and fluorescence intensity parameters. This approach, together with the operation of the single adaptable laser source, can serve as a new theranostics method in personalized medicine in the future not only limited to treat retinal diseases.

Related publications

Permalink: https://www.hzdr.de/publications/Publ-32597
Publ.-Id: 32597


A novel approach for the geospatial modelling and resource assessment of tailings storage facilities

Blannin, R.; Frenzel, M.; Gutzmer, J.

Tailings are the fine-grained residues of ore processing operations, typically stored in dedicated tailings storage facilities (TSFs). Despite being viewed as ‘waste’ materials, tailings can contain significant amounts of valuable metals which were not recovered by original processing techniques or were previously not of economic interest. Re-processing of tailings deposits for the recovery of remaining metals has the additional benefits of mitigation of environmental hazards posed by the TSFs, such as Acid Mine Drainage (AMD). The estimation of mineral resources requires the construction of accurate and reproducible geospatial models. However, the sedimentary-style deposition and subsequent weathering of tailings results in a complex internal structure which is challenging to model, with a laterally and vertically heterogeneous distribution of the minerals comprising the residues. The present study investigates a novel approach for the geospatial modelling of a TSF case study. The surface of the tailings deposit was densely sampled in order to assess the intrinsic horizontal variability. Drill core samples were taken from a depth of 1-3 m, on a 30 m grid and nested grids of 15 m and 7.5 m, with additional random and twin holes. The entire depth of the TSF was sampled in 2 m intervals with a total of 10 drill holes to assess vertical variability. All drill core samples were analysed with x-ray fluorescence spectrometry and inductively coupled plasma mass spectrometry. The compositional data was log-ratio-transformed and variography and subsequent ordinary kriging and co-kriging were performed on the surface samples. The variogram models obtained for the surface samples were then applied for kriging of the deeper layers. Historical photographs of the surface of the TSF were used to improve estimates with co-kriging for the corresponding layers. The entire data set will be used to determine the most efficient sampling approach for the resource estimation of TSFs.

  • Open Access Logo Contribution to proceedings
    European Geosciences Union General Assembly 2021, 26.-30.04.2021, Vienna, Austria
    DOI: 10.5194/egusphere-egu21-2992

Permalink: https://www.hzdr.de/publications/Publ-32595
Publ.-Id: 32595


Grobstruktursimulation blasenbehafteter Strömungen mittels eines hybriden Mehrphasenmodells

Meller, R.

Kurzfassung

In einer Vielzahl industrieller Prozesse spielen Strömungen mit verschiedenen gasförmigen und flüssigen Phasen eine wichtige Rolle. Die Phasengrenzflächen bilden sehr große Strukturen aus, wie z. B. eine freie Wasseroberfläche. Gleichzeitig können kleine, s. g. disperse Strukturen wie Gasbläschen auftreten. Um auch komplexe Prozesse zu simulieren ohne die Art der Strömung im Vorhinein zu kennen, werden unterschiedliche Methoden zur numerischen Beschreibung der verschiedenen Strömungstypen miteinander kombiniert. In der vorliegenden Arbeit wird die Euler-Euler-Methode für disperse Strukturen mit der algebraischen Volume-Of-Fluid-Methode für großskalige Phasengrenzflächen kombiniert. Das auf diese Weise formulierte hybride Mehrphasenmodell wird im Mehr-Fluid-Modell für eine beliebige Anzahl von Phasen formuliert, d. h. für jede vorhandene Phase gelten individuelle Erhaltungsgleichungen für Masse und Impuls. Für disperse Strömungen werden Formulierungen aus der Literatur für den Strömungswiderstand und die virtuelle Masse von Gasblasen genutzt, um den Impulsaustausch zwischen den verschiedenen Phasen zu beschreiben. Für großskalige Phasengrenzflächen wird das Widerstandsmodell von Štrubelj und Tiselj (2011) verwendet, mit dessen Hilfe die Impulserhaltungsgleichungen der individuellen Phasen stark aneinander gekoppelt werden. Zur Beschreibung des Platzens von Gasbläschen an einer freien Oberfläche wird eine neue Formulierung des Phasentransfers eingeführt, womit disperses in kontinuierliches Gas überführt wird.
Für die numerische Lösung des resultierenden Gleichungssystems wird die kompakte Impulsinterpolation von Cubero et al. (2014) genutzt. Die starke Kopplung der phasen-spezifischen Gleichungen für den Impulserhalt erfordert besondere numerische Maßnahmen, um das gesamte Gleichungssystem effizient zu lösen. Dazu wird die Methode der partiellen Eliminierung von Spalding (1981) durch eine Summenformulierung zur näherungsweise Auflösung dieser Kopplung auf das Mehr-Fluid-Modell erweitert. Anhand von zwei- und dreidimensionalen Fällen von aufsteigenden einzelnen Gasblasen wird nachgewiesen, dass das hybride Modell das Verhalten des Ein-Fluid-Modells zur Beschreibung großskaliger Phasengrenzflächen beschreiben kann. Darüber hinaus wird die Funktionsweise der Methode demonstriert, die Interaktion zwischen kleinen Gasbläschen und großskaliger Phasengrenzflächen zu beschreiben. Dies schließt den Phasentransfer von dispersem zu kontinuierlichem Gas ein.
In der Realität sind viele Strömungen turbulent und analog zu den Phasengrenzflächen sind die turbulenten Wirbel typischerweise von sehr verschiedenen Längenskalen. Ein möglicher Weg, solche Probleme numerisch zu beschreiben, ist die Grobstruktursimulation (engl. large-eddy simulation). Dazu werden die Erhaltungsgleichungen räumlich tiefpass-gefiltert. Dadurch entstehen im hiesigen Mehr-Fluid-Modell fünf ungeschlossene Feinstrukturterme, zu denen die Terme der konvektiven Feinstrukturspannungen und der Feinstruktur-Oberflächenspannung gehören. Für die Abschätzung dieser beiden Terme werden unterschiedliche Modelle genutzt. Bei manchen dieser Modelle wird die Struktur der Phasengrenzfläche direkt berücksichtigt. Der Einfluss dieser Modelle auf die Interaktion zwischen der Turbulenz und der Phasengrenzfläche wird anhand von Testfällen einzelner aufsteigender Gasblasen a posteriori untersucht.

Abstract

Flows of gaseous and liquid phases play an important role in numerous industrial processes. The interface, which is the contact surface between different immiscible phases, may form large structures, e.g., a free water surface. At the same time small, so-called disperse structures such as micro gas bubbles may appear.In order to numerically describe such complex processes without knowing the type of flow in advance, different methods for the numerical description of different kinds of flows are combined with each other. In the present work the Euler-Euler method is applied for disperse structures and the algebraic volume-of-fluid method is used to describe large scale interfaces. The resulting hybrid multiphase model is formulated in the context of the multi-fluid model for an arbitrary number of phases, i.e., for each phase present individual conservation equations are considered for mass and momentum. This requires the definition of model forces to express the momentum transfer between different phases. For disperse flows appropriate formulations for drag and virtual mass of gas bubbles from the literature are employed. For large scale interfaces the drag model of Štrubelj and Tiselj (2011) is used, which strongly couples the momentum equations of the individual phases together. In order to describe the process of gas bubbles bursting at a free surface a new phase transfer formulation is introduced, such that disperse gas can be turned into continuous one.
The compact momentum interpolation according to Cubero et al. (2014) is utilized for the numerical solution of the resulting system of equations. The strong coupling of phase specific momentum conservation equations requires special treatment to allow the system of equations to be numerically solved in an efficient way. Therefore, the partial elimination algorithm of Spalding (1981) is expanded to the multi-field model via a sum formulation with the goal of an approximate resolution of phase coupling. The functionality of the hybrid method to reproduce the behaviour of the one-fluid model for the description of large scale interfaces is proven with several two- and three-dimensional test cases considering individual rising gas bubbles. Furthermore, the method's ability to predict interactions of small gas bubbles and large scale interfaces is demonstrated, which includes the phase transfer from disperse to continuous gas.
In reality many flows are turbulent and the according eddies are typically of widely varying length scales, just as it is the case for interfacial structures. Large-eddy simulation is a common approach to describe such problems numerically. Therefore, the conservation equations are spatially low-pass filtered, which leads to five unclosed sub-grid scale terms in the case of the presented multi-fluid model. Two of them are the convective sub-grid stress and the sub-grid surface tension term, which are modelled via several individual formulations taking the interface into account. The model influence on the interaction between turbulence and interface is assessed a posteriori considering single rising gas bubbles.

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  • Doctoral thesis
    Universität der Bundeswehr München, 2021
    Mentor: Prof. Dr.-Ing. habil. Markus Klein
    183 Seiten

Permalink: https://www.hzdr.de/publications/Publ-32586
Publ.-Id: 32586


Classification and resolution adaptive drag modelling of gas-liquid interfaces with a multifield two-fluid model

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

Reliable techniques for the numerical simulation of gas-liquid flows at industrial scales are of great interest for safety analysis and efficiency optimisation, e.g. in nuclear power or metal processing industries. This type of simulation is hard to carry out due to the immense range of scales, which is spanned by interfacial and turbulent structures. For this purpose, hybrid morphology-adaptive numerical frameworks are being developed in the recent years, combining different well established numerical methods for individual flow regimes. The present work follows the approach of Meller et al. (Int J Numer Meth Fluids. 2021; 93: 748-773), who utilise the Euler-Euler approach to statistically describe multiphase structures in dispersed flow regimes, such as bubbly flows, as a basis. At the same time, regimes with resolved gas-liquid interfaces, such as large rising gas bubbles or horizontal interfaces in stratified flows, are captured by means of a Volume-of-Fluid-like method (Tekavčič et al., Nucl Eng Des. 2021; 379: 111223). A fully morphology-adaptive numerical framework needs to comprise transitions between the aforementioned regimes. Hence, the limits of both underlying basic numerical approaches need to be pushed towards and beyond an overlapping region of grid resolution with adequate predictive power, such that the whole spectrum of length scales is covered, forming the basis of morphology transitions.
For this purpose, the present work focuses on the extension of the Volume-of-Fluid methodology towards reliable resolved simulations of gas-liquid interfaces with very coarse grid resolutions. By means of the underlying two-fluid model, an interfacial slip velocity in the interface region becomes generally possible and can be chosen physically motivated. The flow in the vicinity of the interface needs to be classified. For this purpose, the latter is categorised to be of shear type, stagnant type or in between the two. Furthermore, a dimensionless grid spacing is evaluated based on the shear stress across the interface, similarly to the y+ value for the cell thickness of wall-bounded flows. Besides that, interface curvature is considered in relation to grid spacing. From these information, a degree of under-resolution of the interface is determined, which subsequently serves as a criterion for the drag modelling framework. On this basis, interfacial drag coupling is manipulated, such that interfacial slip can take place in the direction tangential to the interface, whenever required. While the interfacial drag formulation of Štrubelj and Tiselj (Int J Numer Methods Engng. 2011; 85: 575-590) is used in case of proper resolution, the closure formulations of Porombka and Höhne (Chem Eng Sci. 2015; 134: 348-459) or Marschall (Technical University of Munich, PhD Thesis, 2011) are considered for portions of the computational domain, where interfaces are classified to be under-resolved. The functionality of the described procedure is validated in cases of 2D and 3D rising gas bubbles, considering their shape and rising velocity. Moreover, gas and liquid velocity profiles of a stratified flow serve as a validation in an additional flow regime.
In this way, the numerical prediction of the gas-liquid interface is improved, pushing the limit of spatial resolutions with adequately reliable predictions towards extremely coarse computational grids, which is the prerequisite for efficient numerical simulations in large-scale applications.

  • Lecture (Conference)
    30th International Conference Nuclear Energy for New Europe, 06.-09.09.2021, Bled, Slowenien

Permalink: https://www.hzdr.de/publications/Publ-32585
Publ.-Id: 32585


Revealing inflammatory indications induced by titanium alloy wear debris in periprosthetic tissue by label-free correlative high-resolution ion, electron and optical micro-spectroscopy

Podlipec, R.; Punzón-Quijorna, E.; Pirker, L.; Kelemen, M.; Vavpetič, P.; Kavalar, R.; Hlawacek, G.; Štrancar, J.; Pelicon, P.; Fokter, S. K.

The metallic-associated adverse local tissue reactions (ALTR) and events accompanying worn-broken implant materials are still poorly understood on the subcellular and molecular lev-el. Current immunohistochemical techniques lack spatial resolution and chemical sensitivity to investigate causal relations between material and biological response on submicron or even na-noscale. In our study, new insights of titanium alloy debris-tissue interaction were revealed by the implementation of label-free high-resolution correlative microscopy approaches. Wear debris chemical and biological impact on the surrounding periprosthetic tissue obtained at revision surgery of a fractured titanium-alloy modular neck of a patient with hip osteoarthritis was suc-cessfully characterized by applying a combination of photon, electron and ion beam mi-cro-spectroscopy techniques, that includes hybrid optical fluorescence and reflectance mi-cro-spectroscopy, scanning electron microscopy (SEM), Energy-dispersive X-ray Spectroscopy (EDS), helium ion microscopy (HIM) and micro-particle-induced X-ray emission (micro-PIXE). Micron-sized wear debris was found as the main cause of the tissue oxidative stress exhibited through lipopigments accumulation in the nearby lysosomes. Furthermore, insights on extensive fretting and corrosion of the debris on nm scale and a quantitative measure of significant Al and V release into the tissue together with hydroxyapatite-like layer formation particularly bound to the regions with the highest Al content were revealed. The functional and structural information obtained at the molecular and subcellular level contributes to a better understanding of the mac-roscopic inflammatory processes observed on the tissue level. The established label-free correla-tive microscopy approach can efficiently be adopted to study any other clinical cases related to ALTR.

Keywords: Adverse Local Tissue Reactions (ALTR); periprosthetic tissue; Titanium alloy wear debris; correlative microscopy; confocal fluorescence and reflectance microscopy; FLIM; SEM-EDS; HIM; micro-PIXE; fHSI

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Permalink: https://www.hzdr.de/publications/Publ-32584
Publ.-Id: 32584


SEM-EDS datasets of titanium alloy wear debris in periprosthetic tissue

Podlipec, R.; Pirker, L.

SEM-EDS images and datasets of titanium alloy wear debris found in periprosthetic tissue obtained at revision surgery of a fractured titanium-alloy modular neck of a patient with hip osteoarthritis.

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-04-30
    DOI: 10.14278/rodare.965
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-32582
Publ.-Id: 32582


Pump-probe data for "A Two‐Dimensional Polyimide‐Graphene Heterostructure with Ultra‐fast Interlayer Charge Transfer"

Li, J.; Pashkin, O.; Schneider, H.; Helm, M.

Pump-probe traces of transient absorption change for graphene, protonated 2DPI and protonated 2DPI on graphene

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  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-04-30
    DOI: 10.14278/rodare.963

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Permalink: https://www.hzdr.de/publications/Publ-32581
Publ.-Id: 32581


Solutions for the Ages – a Short Crash Course on Sustainable Software Development

Huste, T.

As part of the International Virtual Covid Challenge this talk gives an introduction on sustainable software development. Basing on the HIFIS course "Let's Make Your Script Ready for Publication" it details the steps necessary to build a sustainable software application that can easily be cited in a scientific publication.

Keywords: Software; Sustainability; Licensing; Open Source

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    International Virtual Covid Data Challenge 2021, 29.04.2021, Online, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-32579
Publ.-Id: 32579


Data for: Sensitivity of PS/CoPd Janus particles to an external magnetic field

Eichler-Volf, A.; Alsaadawi, Y.; Vazquez Luna, F.; Khan, Q. A.; Stierle, S.; Xu, C.; Heigl, M.; Fekri, Z.; Zhou, S.; Zahn, P.; Albrecht, M.; Steinhart, M.; Erbe, A.

Movies show the 90-degrees rotation of PS/CoPd Janus particles in weak and strong magnetic fields

EDX/SEM/XRD data were used  to characterize the the CoPd particles

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-04-29
    DOI: 10.14278/rodare.959
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-32578
Publ.-Id: 32578


HELIPORT (HELmholtz ScIentific Project WORkflow PlaTform)

Voigt, M.; Ufer, R.; Schacht, W.; Knodel, O.; Pape, D.; Lokamani, M.; Müller, S.

The guidance system HELIPORT aims to make the entire life cycle of a project at the HZDR searchable, accessible, complete and reusable according to the FAIR principles, mentioned below. In particular, our data management solution deals with the areas from the generation of the data to the publication of primary research data, the workflows carried out and the actual research results. For this purpose, a concept was developed which shows the various essential components and their connections. Descriptions of the individual components can be found in our RODARE publication: 10.14278/rodare.252

Keywords: metadata; HELIPORT; project livecycle; FAIR; data managment

  • Software in the HZDR data repository RODARE
    Publication date: 2021-04-19
    DOI: 10.14278/rodare.946
    License: GPL-3.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-32577
Publ.-Id: 32577


Update on Radiation Studies for MU2E-II (and MU2E)

Müller, S.

Presentation at "Mu2e-II Snowmass22 Workshop", 28.04.2021

Keywords: FLUKA; MU2E

  • Lecture (Conference) (Online presentation)
    Mu2e-II Snowmass22 Workshop, 28.04.2021, FERMILAB (virtual), USA

Permalink: https://www.hzdr.de/publications/Publ-32576
Publ.-Id: 32576


Data for: Comparison of Elemental Analysis Techniques for the Characterization of Commercial Alloys

Seidel, P.

The uploaded XRF, OES, and LIBS data served as base for the publication by Seidel et al. 2021 in the journal Metals.

Keywords: Metals; Element analysis; XRF

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-04-29
    DOI: 10.14278/rodare.957
    License: CC-BY-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-32575
Publ.-Id: 32575


Demonstration of a compact plasma accelerator powered by laser-accelerated electron beams

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

Plasma wakefield accelerators are capable of sustaining gigavolt-per-centimeter accelerating
fields, surpassing the electric breakdown threshold in state-of-the-art accelerator modules by
3-4 orders of magnitude. Beam-driven wakefields offer particularly attractive conditions for
the generation and acceleration of high-quality beams. However, this scheme relies on
kilometer-scale accelerators. Here, we report on the demonstration of a millimeter-scale
plasma accelerator powered by laser-accelerated electron beams. We showcase the acceleration
of electron beams to 128 MeV, consistent with simulations exhibiting accelerating
gradients exceeding 100 GVm⁻¹. This miniaturized accelerator is further explored by
employing a controlled pair of drive and witness electron bunches, where a fraction of the
driver energy is transferred to the accelerated witness through the plasma. Such a hybrid
approach allows fundamental studies of beam-driven plasma accelerator concepts at widely
accessible high-power laser facilities. It is anticipated to provide compact sources of energetic
high-brightness electron beams for quality-demanding applications such as free-electron
lasers.

Keywords: Laser; Plasma; High energy electrons; X-Rays; Hybrid; High brightness

Permalink: https://www.hzdr.de/publications/Publ-32574
Publ.-Id: 32574


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