Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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35368 Publications

Inverting the Beamline

Steinbach, P.

In many domains of modern physics, we encounter the situation that generations of scientists have created high precision simulations of the effects under study. Today, these simulations have become essential to the scientific method. However, these
(often mechanistic) simulations of high predictive power carry with them a burden of inference. Once a forward process has been simulated, an inversion of a simulation given observed data from experiments is challenging, sometimes even impossible.

In this presentation, I'd like to provide an introduction to simulation based inference for inverting a beamline simulation at BESSY in Berlin. In this project, I studied the inversion of a beamline simulation using state-of-the-art machine learning. We will start our journey with normalizing flows, walk by conditional invertible neural networks and finish with Automatic Posterior Transformation for Likelihood-Free Inference. To stay with the metaphor: please bring your mathematical boots, wear a hat of Bayes Law and bring your best compass of statistics - otherwise you likely get lost in about a quarter of the presentation.

Keywords: beamline; simulation; normalizing flows; posterior; inverse problem; machine learning

  • Open Access Logo Lecture (others) (Online presentation)
    Institutsseminar des Institut für Kern- und Teilchenphysik der TU Dresden, 10.06.2021, Dresden, Deutschland

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-32750
Publ.-Id: 32750


Indikatoren für Open Science: Report des Helmholtz Open Science Forum

Ferguson, L. M.; Pampel, H.; Bertelmann, R.; Dirnagl, U.; Zohbi, J.; Kapitza, D.; Keup-Thiel, E.; Konrad, U.; Lorenz, S.; Mittermaier, B.; Rechid, D.; Schuck-Zöller, S.

Open Access, Open Research Data und Open Research Software: Diese Themen prägen die aktuellen Diskussionen zu Open Science in der Helmholtz-Gemeinschaft. Doch an welchen Indikatoren lässt sich der Kulturwandel hin zu Open Science festmachen? Und welche Anreize setzen Indikatoren für die Entwicklung von Open Access? Diesen und weiteren Fragen widmete sich das virtuelle Helmholtz Open Science Forum unter dem Motto „Indikatoren für Open Science“ am 20. Januar 2021. Im Zuge der Veranstaltung wurden anhand von Impuls- und Praxisvorträgen Indikatoren für Open Science vorgestellt, untersucht und mit einem breiten Publikum aus der Helmholtz-Gemeinschaft diskutiert. Dieser Report fasst die Vorträge und Diskussionen des Forums zusammen und bietet eine Basis für weitere Entwicklungen des Themenfeldes in der Gemeinschaft.

Keywords: Open Access; Softwareentwicklung; Software Development; Indikatoren; Indicators; Helmholtz Gemeinschaft; Open Science

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Permalink: https://www.hzdr.de/publications/Publ-32748
Publ.-Id: 32748


Heliport Project Poster

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

The HELIPORT project 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.

Keywords: Data Management; Heliport; Metadata; Data provenance; FAIR

  • Open Access Logo Poster (Online presentation)
    Info event for the second project call of the Helmholtz Incubator Platform Helmholtz Metadata Collaboration (HMC), 15.06.2021, Berlin, Germany

Permalink: https://www.hzdr.de/publications/Publ-32745
Publ.-Id: 32745


Superradiant many-qubit absorption refrigerator

Kloc, M.; Meier, K.; Hadjikyriakos, K.; Schaller, G.

We show that the lower levels of a large-spin network with a collective anti-ferromagnetic interaction and collective couplings to three reservoirs may function as a quantum absorption refrigerator. In appropriate regimes, the steady-state cooling current of this refrigerator scales quadratically with the size of the working medium, i.e., the number of spins. The same scaling is observed for the noise and the entropy production rate.

Keywords: open quantum systems; collective interactions; quantum heat engine; quantum absorbtion refrigerator; Dicke superradiance

Permalink: https://www.hzdr.de/publications/Publ-32744
Publ.-Id: 32744


Non-equilibrium boundary driven quantum systems: models, methods and properties

Gabriel, T. L.; Dario, P.; Gernot, S.

Recent years have seen tremendous progress in the theoretical understanding of quantum systems driven dissipatively by coupling them to different baths at their edges. This was possible because of the concurrent advances in the models used to represent these systems, the methods employed, and the analysis of the emerging phenomenology. Here we aim to give a comprehensive review of these three integrated research directions. We first provide an overarching view of the models of boundary driven open quantum systems, both in the weak and strong coupling regimes. This is followed by a review of state-of-the-art analytical and numerical methods, both exact, perturbative and approximate. Finally, we discuss the transport properties of some paradigmatic one-dimensional chains, with an emphasis on disordered and quasiperiodic systems, the emergence of rectification and negative differential conductance, and the role of phase transitions.

Keywords: open quantum systems; quantum transport; phase transitions; local and global master equations; chain models

Permalink: https://www.hzdr.de/publications/Publ-32743
Publ.-Id: 32743


Morphology-Tunable Synthesis of Intrinsic Room-Temperature Ferromagnetic γ-Fe2O3 Nanoflakes

Jia, Z.; Wang, W.; Li, Zichao; Sun, R.; Zhou, Shengqiang; Leonard Deepak, F.; Su, C.; Li, Y.; Wang, Z.

Intrinsic two-dimensional (2D) magnetic materials with room-temperature ferromagnetism and air stability are highly desirable for spintronic applications. However, the experimental observations of such 2D or ultrathin ferromagnetic materials are rarely reported owing to the scarcity of these materials in nature and for the intricacy in their synthesis. Here, we report a successful controllable growth of ultrathin γ-Fe2O3 nanoflakes with a variety of morphologies tunable by the growth temperature alone using a facile chemical vapor deposition method and demonstrate that all ultrathin nanoflakes still show intrinsic room-temperature ferromagnetism and a semiconducting nature. The γ-Fe2O3 nanoflakes epitaxially grown on α-Al2O3 substrates take a triangular shape at low temperature and develop gradually in lateral size, forming eventually a large-scale γ-Fe2O3 thin film as the growth time increases due to a thermodynamic control process. The morphology of the nanoflakes could be tuned from triangular to stellated, petaloid, and dendritic crystalloids in sequence with the rise of precursor temperature, revealing a growth process from thermodynamically to kinetically dominated control. Moreover, the petaloid and dendritic nanoflakes exhibit enhanced coercivity compared with the triangular and stellated nanoflakes, and all the nanoflakes with diverse shapes possess differing electrical conductivity. The findings of such ultrathin, air-stable, and room-temperature ferromagnetic γ-Fe2O3 nanoflakes with tunable shape and multifunctionality may offer guidance in synthesizing other non-layered magnetic materials for next-generation electronic and spintronic devices.

Keywords: γ-Fe2O3 nanoflakes; morphology tunable synthesis; room-temperature ferromagnetism; coercivity; resistivity

Permalink: https://www.hzdr.de/publications/Publ-32739
Publ.-Id: 32739


The response of the accumulator plants Noccaea caerulescens, Noccaea goesingense and Plantago major towards the uranium

Burger, A.; Weidinger, M.; Baumann, N.; Vesely, A.; Lichtscheidl, I.

Uranium (U) is a naturally occurring metal; its environmental levels can be increased due to processes in the nuclear industry and fertilizer production. The transfer of U in the food chain from plants is associated with deleterious chemical and radiation effects. To date, limited information is available about U toxicity on plant physiology. This study investigates the responses of metal-accumulating plants to different concentrations of U. The plants Noccaea caerulescens and Noccaea goesingense are known as metal hyperaccumulators and therefore could serve as candidates for the phytoremediation of radioactive hotspots; Plantago major is a widely used pharmaceutical plant that pioneers polluted grounds and therefore should not contain high concentrations of toxic elements. The experimental plants were grown hydroponically at U concentrations between 1 μM and 10 mM. The content of U and essential elements was analyzed in roots and leaves by ICP-MS. The amount of accumulated U was influenced by its concentration in the hydroponics. Roots contained most of the metal, whereas less was transported up to the leaves, with the exception of N. goesingense in a medium concentration of U. U also influenced the nutrient profile of the plants. We localized the U in plant tissues using EDX in the SEM. U was evenly distributed in roots and leaves of Noccaea species, with one exception in the roots of N. goesingense, where the central cylinder contained more U than the cortex. The toxicity of U was assessed by measuring growth and photosynthetic parameters. While root biomass of N. caerulescens was not affected by U, root biomass of N. goesingense decreased significantly at high U concentrations of 0.1 and 10 mM and root biomass of P. major decreased at 10 mM U. Dry weight of leaves was decreased at different U concentrations in the three plant species; a promotive effect was observed in N. caerulescens at lowest concentration offered. Chlorophyll a fluorescence was not affected or negatively affected by U in both Noccaea species, whereas in Plantago also positive effects were observed. Our results show that the impact of U on Plantago and Noccaea relates to its external concentration and to the plant species. When growing in contaminated areas, P. major should not be used for medicinal purpose. Noccaea species and P. major could immobilize U in their rhizosphere in hotspots contaminated by U, and they could extract limited amounts of U into their leaves.

Keywords: Accumulation; Chemotoxicity; Distribution; Localization; Uptake; Uranium

Permalink: https://www.hzdr.de/publications/Publ-32738
Publ.-Id: 32738


High-field spin-flop state in green dioptase

Prokhnenko, O.; Marmorini, G.; Nikitin, S. E.; Yamamoto, D.; Gazizulina, A.; Bartkowiak, M.; Ponomaryov, O.; Zvyagin, S.; Nojiri, H.; Diaz-Ortega, I. F.; Anovitz, L. M.; Kolesnikov, A. I.; Podlesnyak, A.

The high-field magnetic properties and magnetic order of the gem mineral green dioptase Cu6[Si6O18] · 6H2O have been studied by means of single-crystal neutron diffraction in magnetic fields up to 21 T and magnetization measurements up to 30 T. In zero field, the Cu2+ moments in the antiferromagnetic chains are oriented along the c axis with a small off-axis tilt. For a field applied parallel to the c axis, the magnetization shows a spin-flop-like transition at B = 12.2 T at 1.5 K. Neutron diffraction experiments show a smooth behavior in the intensities of the magnetic reflections without any change in the periodicity of the magnetic structure. Bulk and microscopic observations are well described by a model of ferromagnetically coupled antiferromagnetic XXZ spin- 1/2 chains, taking into account a change of the local easy-axis direction.We demonstrate that the magnetic structure evolves smoothly from a deformed Néel state at low fields to a deformed spin-flop state in a high field via a strong crossover around B. The results are generalized for different values of interchain coupling and spin anisotropy.

Permalink: https://www.hzdr.de/publications/Publ-32736
Publ.-Id: 32736


ALFERROCK Heat Storage Systems in the Chemical Process Industry

Hampel, U.; Unger, S.; Vishwakarma, V.; Bangalore Mohankumar, M.

Energy storage is a central element of future energy systems. In the process industry, the storage of heat is of particular importance. The talk discusses possible applications of high-temperature heat storage in thermal separation processes using the example of a new heat storage material produced from bauxite residues by the company Alferrock GmbH.

Keywords: heat storage; sensible heat storage; high-temperature heat storage; chemical industry; distillation

  • Invited lecture (Conferences) (Online presentation)
    72. BHT - Freiberger Universitätsforum, 09.-11.06.2021, Freiberg, Germany

Permalink: https://www.hzdr.de/publications/Publ-32734
Publ.-Id: 32734


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

  • 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


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


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


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


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


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

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

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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


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.

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

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


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


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


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

Downloads:

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


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

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

Downloads:

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


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

Downloads:

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

Downloads:

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


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


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


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

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

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  • Secondary publication expected from 04.05.2022

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


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).

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

Downloads:

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.

  • 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


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


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.

  • 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

Related publications

  • 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

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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

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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


Large eddy simulation of the fluid–structure interaction in an abstracted aquatic canopy consisting of flexible blades

Tschisgale, S.; Löhrer, B.; Meller, R.; Fröhlich, J.

The paper addresses the fluid–structure interaction of submerged aquatic canopies, with particular focus on the complex interplay between coherent flow structures and the motion of vegetation elements. New insights into the underlying mechanisms are gained from a large eddy simulation of a submerged model canopy flow. The model canopy is made up of 800 highly flexible blades, each individually resolved by an immersed boundary method. The obtained high-resolution flow data reveal well-known coherent turbulent structures, including velocity streaks, Kelvin–Helmholtz (KH) vortices in the mixing layer as well as hairpin (HP) vortices in the outer flow region. The present results show that the interaction of these prototypical structures plays a key role creating unique turbulent features such as composite KH/HP vortices located between a high-speed and low-speed streak. Under the influence of these pronounced eddies, groups of blades respond by a strong local reconfiguration. Due to the convection of the coherent structures by the mean flow this causes an apparent wave-like motion of the canopy in streamwise direction, known as monami. A frequency analysis of this phenomenon shows that the vegetation responds almost passively, merely reflecting local flow conditions.

Keywords: flow–structure interactions; turbulent boundary layers

Permalink: https://www.hzdr.de/publications/Publ-32572
Publ.-Id: 32572


An experimental investigation of light emission produced in the process of positronium formation in matter

Pietrow, M.; Zaleski, R.; Wagner, A.; Słomski, P.; Hirschmann, E.; Krause-Rehberg, R.; Liedke, M. O.; Butterling, M.; Weinberger, D.

The excess energy emitted during the positronium (Ps) formation in condensed matter may be released as light. Spectroscopic analysis of this light can be a new method of studying the electronic properties of materials. We report the first experimental attempt, according to our knowledge, to verify the existence of this emission process. As a result, the possibility of the emission of photons during Ps formation is within the experimental uncertainty in two different solids: an n-alkane and porous silica. However, it seems that the Ps formation on the alkane surface is not accompanied by the emission of photons with energy in the detection range of 1.6 – 3.8 eV. Various processes that can influence the energy of the photon emitted during the Ps formation are discussed to elucidate this issue. To aid future experiments, equations were developed to estimate the expected ratio of light emission events to annihilation events with the presence or absence of a photon during the Ps formation.

Keywords: positron annihilation lifetime spectroscopy; ELBE; MePS; EPOS; porosity; positronium

  • Physical Chemistry Chemical Physics 23(2021)19, 11264-11271
    Online First (2021) DOI: 10.1039/d1cp00755f

Permalink: https://www.hzdr.de/publications/Publ-32571
Publ.-Id: 32571


Modulation of γ-secretase activity by a carborane-based flurbiprofen analogue

Saretz, S.; Basset, G.; Useini, L.; Laube, M.; Pietzsch, J.; Draca, D.; Maksimović-Ivanić, D.; Trambauer, J.; Steiner, H.; Hey-Hawkins, E.

All over the world, societies are facing rapidly aging populations combined with a growing num-ber of patients suffering from Alzheimer’s disease (AD). One focus in pharmaceutical research to address this issue is on the reduction of the longer amyloid-β (Aβ) fragments in brain by modula-tion of γ-secretase, a membrane-bound protease. R-Flurbiprofen (tarenflurbil) was studied in this regard, but failed to show significant improvement in AD patients in a phase 3 clinical trial. This was mainly attributed to its low ability to cross the blood-brain barrier (BBB). We here present the synthesis and in vitro evaluation of a racemic meta-carborane analogue of flurbiprofen. By intro-ducing the carborane moiety, the hydrophobicity could be shifted into a more favourable range for the penetration of the blood-brain barrier, evident by a logD7.4 value of 2.0. Furthermore, our analogue retained γ-secretase modulator activity in comparison to racemic flurbiprofen in a cell-based assay. These findings demonstrate the potential of carboranes as phenyl mimetics also in AD research.

Keywords: Alzheimer; Carborane; Flurbiprofen; γ-Secretase modulator (GSM); Small molecule; Amyloid-β (Aβ) peptide; Phenyl mimetic

Permalink: https://www.hzdr.de/publications/Publ-32567
Publ.-Id: 32567


Reactivation of magma pathways: Insights from field observations, geochronology, geomechanical tests and numerical models

Thiele, S. T.; Cruden, A. R.; Zhang, X.; Micklethwaite, S.; Matchan, E. L.

Field observations and unmanned aerial vehicle surveys from Caldera Taburiente (La Palma, Canary Islands, Spain) show that pre-existing dykes can capture and re-direct younger ones to form multiple dyke composites. Chill margins suggest that the older dykes were solidified and cooled when this occurred. In one multiple dyke example, an 40Ar/39Ar age difference of 200 kyr was determined between co-located dykes. Petrography and geomechanical measurements (ultrasonic pulse and Brazilian disc tests) show that a microscopic preferred alignment of plagioclase laths and sheet-like structures formed by non-randomly distributed vesicles give the solidified dykes anisotropic elastic moduli and fracture toughness. We hypothesise that this anisotropy led to the development of margin-parallel joints within the dykes, during subsequent volcanic loading. Finite element models also suggest that the elastic contrast between solidified dykes and their host rock elevated and re-oriented the stresses that governed subsequent dyke propagation. Thus, the margin-parallel joints, combined with local concentration and rotation of stresses, favoured the deflection of subsequent magma-filled fractures by up to 60° to form the multiple dykes. At the edifice scale, the capture and deflection of active intrusions by older ones could change the organisation of volcanic magma plumbing systems and cause unexpected propagation paths relative to the regional stress. We suggest that reactivation of older dykes by this mechanism gives the volcanic edifice a structural memory of past stress states, potentially encouraging the re-use of older vents and deflecting intrusions along volcanic rift zones or towards shallow magma reservoirs.

Keywords: multiple dyke; elastic anisotropy; fracture deflection; mechanical discontinuity; reactivation; Quaternary; basalt Ar-Ar dating; Canary Islands

  • Open Access Logo Journal of Geophysical Research - Solid Earth (2021)
    Online First (2021) DOI: 10.1029/2020JB021477

Permalink: https://www.hzdr.de/publications/Publ-32563
Publ.-Id: 32563


Data: Finite-element dynamic-matrix approach for spin-wave dispersions in magnonic waveguides with arbitrary cross section

Körber, L.; Quasebarth, G.; Otto, A.; Kakay, A.

This repository contains data generated to showcase our developed micromagnetic method described in our paper "Finite-element dynamic-matrix approach for spin-wave dispersions in magnonic waveguides with arbitrary cross section". For each example in Section V, we provide

  • .clc and .spc files containing important material and experimental parameters
  • .geo files containing the sample geometry (gmsh files)
  • .csv files containing the dispersions calculated using our eigensolver 

     
  • only for example A: linescans of the mode profiles along the width of the waveguide
  • only for example B: .dat file of the obtained mumax dispersion
  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-04-23
    DOI: 10.14278/rodare.955
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-32562
Publ.-Id: 32562


Origin of the 30 T transition in CeRhIn5 in tilted magnetic fields

Mishra, S.; Gorbunov, D.; Campbell, D. J.; Leboeuf, D.; Hornung, J.; Klotz, J.; Zherlitsyn, S.; Harima, H.; Wosnitza, J.; Aoki, D.; McCollam, A.; Sheikin, I.

We present a comprehensive ultrasound study of the prototypical heavy-fermion material CeRhIn5, examining the origin of the enigmatic 30 T transition. For a field applied at 2° from the c axis, we observed two sharp anomalies in the sound velocity, at Bm ≈ 20 T and B ≈ 30 T, in all the symmetry-breaking ultrasound modes at low temperatures. The lower-field anomaly corresponds to the well-known first-order metamagnetic incommensurate-to-commensurate transition. The higher-field anomaly takes place at 30 T, where an electronic-nematic transition was previously suggested to occur. Both anomalies, observed only within the antiferromagnetic state, are of similar shape, but the corresponding changes of the ultrasound velocity have opposite signs. Based on our experimental results, we suggest that a field-induced magnetic transition from a commensurate to another incommensurate antiferromagnetic state occurs at B. With further increasing the field angle from the c axis, the anomaly at B slowly shifts to higher fields, broadens, and becomes smaller in magnitude. Traced up to 30° from the c axis, it is no longer observed at 40° below 36 T.

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Permalink: https://www.hzdr.de/publications/Publ-32559
Publ.-Id: 32559


Accelerator Programming Using Directives 7th International Workshop, WACCPD 2020, Virtual Event, November 20, 2020, Proceedings

Bhalachandra, S.; Wienke, S.; Chandrasekaran, S.; Juckeland, G.

This book constitutes the proceedings of the 7th International Workshop on Accelerator Programming Using Directives, WACCPD 2020, which took place on November 20, 2021. The workshop was initially planned to take place in Atlanta, GA, USA, and changed to an online format due to the COVID-19 pandemic.
WACCPD is one of the major forums for bringing together users, developers, and the software and tools community to share knowledge and experiences when programming emerging complex parallel computing systems. The 5 papers presented in this volume were carefully reviewed and selected from 7 submissions. They were organized in topical sections named: OpenMP; OpenACC; and Domain-specific Solvers.

Keywords: Compilers; computer networks; CUDA; distributed computer systems; embedded systems; Graphics Processing Unit (GPU); Hardware accelerators; Heterogeneous (hybrid) systems; Massively parallel algorithms; Massively parallel and high-performance simulations

Permalink: https://www.hzdr.de/publications/Publ-32558
Publ.-Id: 32558


Die Rolle von Mikroorganismen bei der Lagerung von hoch-radioaktiven Abfällen - Mikrobiologie am HZDR

Matschiavelli, N.

Durch den Ausstieg Deutschlands aus der Kernkraft tritt immer mehr die dauerhafte und sichere Lagerung der noch hoch-radioaktiven Brennelemente in den Fokus. Aber wie beeinflussen Mikroorganismen die Metalle und Gesteine, aus denen ein Endlager aufgebaut ist? Als Mikrobiologen/innen in der Abteilung für Biogeochemie zeigen wir dir, wie mit modernen biologischen Methoden diese Fragen beantwortet werden.

  • Lecture (others) (Online presentation)
    Gils`& Boys`day am HZDR, 22.04.2021, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-32556
Publ.-Id: 32556


Proton beam quality enhancement by spectral phase control of a PW-class laser system

Ziegler, T.; Albach, D.; Bernert, C.; Bock, S.; Brack, F.-E.; Cowan, T. E.; Dover, N. P.; Garten, M.; Gaus, L.; Gebhardt, R.; Goethel, I.; Helbig, U.; Irman, A.; Kiriyama, H.; Kluge, T.; Kon, A.; Kraft, S.; Kroll, F.; Loeser, M.; Metzkes-Ng, J.; Obst-Huebl, L.; Püschel, T.; Rehwald, M.; Schlenvoigt, H.-P.; Schramm, U.; Zeil, K.

This repository contains the experimental raw data, the analyzed data and corresponding scripts as well as figures for the "Proton beam quality enhancement by spectral phase control of a PW-class laser system" publication.

https://doi.org/10.1038/s41598-021-86547-x

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-04-01
    DOI: 10.14278/rodare.953
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-32554
Publ.-Id: 32554


ExPaNDS Training Catalogue Demo

Knodel, O.

This entry contains a demo video introducing the ExPaNDS/PaNOSC training catalogue developed by HZDR.

Keywords: data management; training; ExPaNDS

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-04-19
    DOI: 10.14278/rodare.942
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-32553
Publ.-Id: 32553


Thermocapillary Effects at Gas Bubbles Growing on Electrodes

Mutschke, G.; Hossain, S. S.; Bashkatov, A.; Yang, X.; Eckert, K.

The contribution summarizes recent progress obtained in our group when studying the dynamics of
hydrogen gas bubbles growing during electrolysis in an aqueous electrolyte. We find that thermocapillary
effects are important to be considered, which lead to characteristic vortical electrolyte flow close to the
bubble [1,2]. We further discuss the resulting force on the bubble and conclude on how the bubble
departure is affected at electrodes of different sizes [3]. This knowledge might contribute to advancing
the efficiency of electrolyzers.

References:
[1] X. Yang et al., Marangoni convection at electrogenerated hydrogen bubbles, Phys. Chem. Chem.
Phys. 20 (2018) 11542.
[2] J. Massing et al., Thermocapillary convection during hydrogen evolution at microelectrodes,
Electrochim. Acta 297 (2019) 929-940.
[3] S.S. Hossain et al., On the thermocapillary effect on gas bubbles growing on electrodes of different
sizes, Electrochim. Acta 353 (2020) 136461.

Keywords: electrolysis; water splitting; gas evolution; thermocapillary effect

  • Lecture (Conference) (Online presentation)
    29th Topical Meeting of the International Society of Electrochemistry, 19.-21.04.2021, Mikulov, Tschechische Republik

Permalink: https://www.hzdr.de/publications/Publ-32552
Publ.-Id: 32552


Macro to generate muon (g-2) summary plot

Müller, S.

This macro gives the status of the muon (g-2) just after the FERMILAB seminar on April 7, 2021.

The theoretical values use the different contributions as given in the

[White Paper](https://arxiv.org/pdf/2006.04822.pdf) of the

[Theory Initiative](https://muon-gm2-theory.illinois.edu/). Since the leading

order hadronic contribution is dominating the uncertainty of the

theoretical values, several values for a$_\mu$ are plotted which use the

different evaluations for the leading order hadronic contribution given in

Table 4 of the White Paper as well as the White Paper average.

Keywords: ROOT; (g-2); Macro

  • Software in the HZDR data repository RODARE
    Publication date: 2021-04-21
    DOI: 10.14278/rodare.950
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-32551
Publ.-Id: 32551


A Two‐Dimensional Polyimide‐Graphene Heterostructure with Ultra‐fast Interlayer Charge Transfer

Liu, K.; Li, J.; Qi, H.; Hambsch, M.; Rawle, J.; Romaní Vázquez, A.; Shaygan Nia, A.; Pashkin, O.; Schneider, H.; Polozij, M.; Heine, T.; Helm, M.; Mannsfeld, S. C. B.; Kaiser, U.; Dong, R.; Feng, X.

Two‐dimensional polymers (2DPs) are a class of atomically/molecularly thin crystalline organic 2D materials. They are intriguing candidates for the development of unprecedented organic‐inorganic 2D van der Waals heterostructures (vdWHs) with exotic physicochemical properties. In this work, we demonstrate the on‐water surface synthesis of large‐area (cm 2 ), monolayer 2D polyimide (2DPI) with 3.1‐nm lattice. Such 2DPI comprises metal‐free porphyrin and perylene units linked by imide bonds. We further achieve a scalable synthesis of 2DPI‐graphene (2DPI‐G) vdWHs via a face‐to‐face co‐assembly of graphene and 2DPI on the water surface. Remarkably, femtosecond transient absorption spectroscopy reveals an ultra‐fast interlayer charge transfer (~60 fs) in the resultant 2DPI‐G vdWH upon protonation by acid, which is equivalent to that of the fastest reports among inorganic 2D vdWHs. Such large interlayer electronic coupling is ascribed to the interlayer cation‐π interaction between 2DP and graphene. Our work opens opportunities to develop 2DP‐based vdWHs via the on‐water surface synthesis strategy and highlights the unique interface‐induced optoelectronic properties.

Keywords: 2D polymer; graphene; van der Waals heterostructure; transient absorption spectroscopy

Related publications

Permalink: https://www.hzdr.de/publications/Publ-32550
Publ.-Id: 32550


A tunable autocorrelator for pulse measurements at IR FEL-oscillator facilities

Cicek, E.; Seidel, W.; Ketenoglu, B.

Radiation characteristics of a Free-Electron Laser (FEL) such as pulse length, timestructure, intensity, bandwidth, wavelength, power, frequency, etc., which were measured on adiagnostics table, are thoroughly discussed. In this respect, pulse length measurements of an InfraredFEL (IR-FEL) beam are evaluated through an intensity autocorrelator, designed and installed as adiagnostics tool at the “Helmholtz-Zentrum Dresden-Rossendorf (HZDR)-Radiation Source ELBE”of Germany. In addition, the autocorrelator was designed as a unique, cost-effective, and in-housesetup. It operates within the wavelength range of 3–35 microns, using Cadmium-Telluride (CdTe)crystals in the Second Harmonic Generation (SHG) medium. The intensity autocorrelation curveswere obtained for the FEL beam with the wavelength of 26.2 microns, indicating an FWHM pulseduration ranging between 3.29–8.03 ps with different optical cavity detuning values. Furthermore,the pulse duration of Ti: sapphire laser beam is measured between 1–3 ps through the designedautocorrelator at the ELBE light source. On the other hand, the setup may pave the way for pulselength measurements of the Turkish infrared FEL-oscillator facility (TARLA) as well, which iscurrently under the hardware installation phase. Finally, it is elaborated in section 3 that the uniqueautocorrelator design fully meets all requirements for pulse length measurements of an infraredFEL source.Radiation characteristics of a Free-Electron Laser (FEL) such as pulse length, timestructure, intensity, bandwidth, wavelength, power, frequency, etc., which were measured on adiagnostics table, are thoroughly discussed. In this respect, pulse length measurements of an InfraredFEL (IR-FEL) beam are evaluated through an intensity autocorrelator, designed and installed as adiagnostics tool at the “Helmholtz-Zentrum Dresden-Rossendorf (HZDR)-Radiation Source ELBE”of Germany. In addition, the autocorrelator was designed as a unique, cost-effective, and in-housesetup. It operates within the wavelength range of 3–35 microns, using Cadmium-Telluride (CdTe)crystals in the Second Harmonic Generation (SHG) medium. The intensity autocorrelation curveswere obtained for the FEL beam with the wavelength of 26.2 microns, indicating an FWHM pulseduration ranging between 3.29–8.03 ps with different optical cavity detuning values. Furthermore,the pulse duration of Ti: sapphire laser beam is measured between 1–3 ps through the designedautocorrelator at the ELBE light source. On the other hand, the setup may pave the way for pulselength measurements of the Turkish infrared FEL-oscillator facility (TARLA) as well, which iscurrently under the hardware installation phase. Finally, it is elaborated in section 3 that the uniqueautocorrelator design fully meets all requirements for pulse length measurements of an infraredFEL source.

Keywords: Beam-line instrumentation (beam position and profile monitors; beam-intensity monitors; bunch lengt

Permalink: https://www.hzdr.de/publications/Publ-32549
Publ.-Id: 32549


The Helmholtz cloud services as well suited platform for sustainable OpenFOAM_RCS development

Schlegel, F.; Greenshields, C.; Huste, T.; Lehnigk, R.; Lucas, D.; Peltola, J.

The presentation gives a comprehensive overview about sustainable software development strategies for OpenFOAM_RCS and how this will be supported by the Helmholtz cloud services in the frame of HIFIS.

Keywords: OpenFOAM; HIFIS; Computational Fluid Dynamics; software development

  • Lecture (Conference) (Online presentation)
    32nd Meeting of German CFD Network of Competence, 16.-17.03.2021, München, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-32544
Publ.-Id: 32544


Experimental electronic stopping cross section of tungsten for light ions in a large energy interval

Moro, M. V.; Wolf, P. M.; Bruckner, B.; Munnik, F.; Heller, R.; Bauer, P.; Primetzhofer, D.

Electronic stopping cross section of tungsten for light ions was experimentally measured in a wide energy interval (20 to 6000 keV for protons and 50 to 9000 keV for helium) in backscattering and transmission geometries. The measurements were carried out in three laboratories (Austria, Germany and Sweden) using five different set-ups, the stopping data deduced from different data sets showed excellent agreement amongst each other, with total uncertainty varying within 1.5–3.8% for protons and 2.2–5.5% for helium, averaged over the respective energy range of each data set. The final data is compared to available data and to widely adopted semi-empirical and theoretical approaches, and found to be in good agreement with most adopted models at energies around and above the stopping maximum. Most importantly, our results extend the energy regime towards lower energies, and are thus of high technological relevance, e.g., in fusion research. At these low energies, our findings also revealed that tungsten – featured with fully and partially occupied f- and d-subshells, respectively – can be modeled as an electron gas for the energy loss process.

Keywords: Stopping power; Tungsten; Free electron gas; Bragg peak; Protons; Helium; Fusion

Permalink: https://www.hzdr.de/publications/Publ-32543
Publ.-Id: 32543


Data/Software for: Dynamics of mono- and poly-disperse two-dimensional foams flowing in an obstructed channel

Lecrivain, G.

This archive contains the raw data and the original code described in the manuscript "Dynamics of mono- and poly-disperse two-dimensional foams flowing in an obstructed channel", submitted in 2020 to Journal of Fluid Mechanics by Thales Carl Lavoratti, Sascha Heitkam, Uwe Hampel, and Gregory Lecrivain. The archive contains the following data:

- C++ code used to simulate the foam dynamics and create the raw data (petsc.tar.gz)

- selected raw data in petsc format. The mono-disperse scenarios V125.tar.gz, V200.tar.gz, V250.tar.gz, V350.tar.gz correspond to the gas fractions \varepsilon = 0.44, 0.68, 0.83, and 0.99, respectively. The poly-disperse scenarios V125r.tar.gz, V200r.tar.gz, V250r.tar.gz, V350r.tar.gz correspond to the gas fractions 0.44, 0.69, 0.84, and 0.99, respectively

- bash and python scripts used to create bubble contours from the petsc raw data (scripts.tar.gz)

- extracted bubble contours (contours.tar.gz)

- python codes used to make figures and animations (figures.tar.gz)

- Mathematica notebook testing the wall potential f(\phi_w) = 0 (potential.nb)

- manuscript data (manuscript.tar.gz)

For further questions, feel free to contact me (g.lecrivain@hzdr.de).

Keywords: Flowing foam; Phase-field simulation; Obstructed channel

  • Software in the HZDR data repository RODARE
    Publication date: 2021-01-12
    DOI: 10.14278/rodare.738
    License: CC-BY-4.0
    Embargo: 30.06.2021

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Permalink: https://www.hzdr.de/publications/Publ-32542
Publ.-Id: 32542


Speciation of Pd in minerals from Norilsk ores by X-ray absorption spectroscopy

Brovchenko, V. D.; Merkulova, M.; Sittner, J.; Renno, A. D.

Определены спектры рентгеновского поглощения (XANES) для Pd в пентландите, Pd в металлической форме (Pd фольга) и Pd в минералах платиновой группы, показывающие большие различия в форме всех спектров. Доказано, что палладий в пентландите не имеет ни металлической формы, ни микропримесей минералов платиновой группы, но входит в кристаллическую решетку пентландита. Энергетическое положение белой линии (3173.8 eV) спектра Pd в пентландите аналогично положению белой линии спектров Pd в минералах платиновой группы. Это свидетельствует о том, что палладий в пентландите имеет номинальное состояние окисления +2. Поэтому можно предположить, что палладий замещает атомы железа или никеля в кристаллической структуре пентландита.
X-ray absorption spectra (XANES) for Pd in pentlandite, Pd in metallic form (Pd foil) and Pd in platinum-group minerals were determined showing large differences in the shape of all spectra. It was proved that palladium in pentlandite is neither in its metal form nor in microinclusions of platinum-group minerals, but is included in the crystal lattice of pentlandite. Energy position of white line (3173.8 eV) of Pd spectrum in pentlandite is similar to the position of white line of Pd spectra in platinum group minerals. This indicates that palladium in pentlandite has a nominal oxidation state of +2. Therefore, we can assume that palladium replaces iron or nickel atoms in the crystal structure of pentlandite.

Keywords: Norilsk; X-Ray Absorption Spectroscopy; Palladium; Pentlandite

  • Open Access Logo Lecture (Conference)
    Металлогения древних и современных океанов – 2021. Сингенез, эпигенез, гипергенез Metallogeny of ancient and modern oceans - 2021. Syngenesis, epigenesis, hypergenesis, 26.-30.04.2021, Миасс - Miass, Russland

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Permalink: https://www.hzdr.de/publications/Publ-32538
Publ.-Id: 32538


Example Project Plan generated by HELIPORT

Voigt, M.; Knodel, O.

This dataset contains the metadata for an example project generated using the project export button in our prototype scientific project lifecycle and workflow management system HELIPORT (HELmholtz ScIentific Project WORkflow PlaTform). The metadata schema is still under development and this entry will be updated to reflect further developments.

Keywords: metadata; HELIPORT; project livecycle; FAIR

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-04-16
    DOI: 10.14278/rodare.938
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-32537
Publ.-Id: 32537


3D CT image

Da Assuncao Godinho, J. R.

3D image, experiment 2

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-04-08
    DOI: 10.14278/rodare.918
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-32534
Publ.-Id: 32534


Dataset for: Chemical absorption measurements in a lab scale bubble column

Kipping, R.; Hampel, U.

This data set contains gas phase hydrodynamic data obtained from ultrafast X-ray tomography measurements in a bubble column. Global and local gas holdups, as well as bubble size distributions are given for I) non reactive conditions with nitrogen (gas) and sodium hydroxide solution (liquid) and II) reactive conditions with carbon dioxide (gas) and sodium hydroxide solution (liquid). Additionally the data set contains the corresponding consumption rates obtained from wire-mesh sensor measurements.

Furhter details on the experiments are explained in the corresponding journal paper.

Keywords: bubble columns; wire-mesh sensor; UFXCT

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-04-13
    DOI: 10.14278/rodare.924

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Permalink: https://www.hzdr.de/publications/Publ-32533
Publ.-Id: 32533


Advancing laser plasma accelerators by means of femto-scale diagnostics for a pilot study of high dose rate in-vivo irradiation

Schramm, U.

Talk on Advancing laser plasma accelerators by means of femto-scale diagnostics for a pilot study of high dose rate in-vivo irradiation

Keywords: laser proton acceleration; high dose rate radiobiology

  • Invited lecture (Conferences) (Online presentation)
    4th international symposium on high power laser science and engineering, HPLSE, 12.-15.04.2021, Suzhou, China

Permalink: https://www.hzdr.de/publications/Publ-32531
Publ.-Id: 32531


Data for: Electron dose rate and oxygen depletion protect zebrafish embryos from radiation damage

Pawelke, J.; Brand, M.; Hans, S.; Hideghéty, K.; Karsch, L.; Leßmann, E.; Löck, S.; Schürer, M.; Szabo, E. R.; Beyreuther, E.

Primary data and data description to publication:

Electron dose rate and oxygen depletion protect zebrafish embryos from radiation damage

Abstract:

Background and purpose
In consequence of a previous study, where no protecting proton Flash effect was found for zebrafish embryos, potential reasons and requirements for inducing a Flash effect should be investigated with the beam pulse structure and the partial oxygen pressure (pO2) as relevant parameters.
Materials and methods
The experiments were performed at the research electron accelerator ELBE, whose variable pulse structure enables dose delivery as electron Flash and quasi-continuously (reference). Zebrafish embryos were irradiated with ~26 Gy either continuously with a dose rate of ~6.7 Gy/min or in one 111 µs long pulse with a pulse dose rate of 109 Gy/s and a mean dose rate of 105 Gy/s, respectively. Using the OxyLite system to measure the pO2 a low- (pO2 ≤ 5 mmHg) and a high-pO2 group were defined on basis of the oxygen depletion kinetics in sealed embryo samples.
Results
A protective Flash effect was seen for most endpoints ranging from 4 % less reduction in embryo length to about 20 – 25 % less embryos with spinal curvature and pericardial edema, relative to reference irradiation. The reduction of pO2 below atmospheric levels (148 mmHg) resulted in higher protection, which was however more pronounced in the low-pO2 group.
Conclusion
The Flash experiment at ELBE showed that the zebrafish embryo model is appropriate for studying the radiobiological response of high dose rate irradiation. Pulse dose and pulse dose rate as important beam parameters were confirmed as well as the pivotal role of pO2 during irradiation.

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-04-15
    DOI: 10.14278/rodare.928

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Permalink: https://www.hzdr.de/publications/Publ-32529
Publ.-Id: 32529


A Robust PtNi Nanoframe/N-Doped Graphene Aerogel Electrocatalyst with Both High Activity and Stability

Yang, J.; Hübner, R.; Zhang, J.; Wan, H.; Zheng, Y.; Wang, H.; Qi, H.; He, L.; Li, Y.; Aregahegn Dubale, A.; Sun, Y.; Liu, Y.; Peng, D.; Meng, Y.; Zheng, Z.; Rossmeisl, J.; Liu, W.

Insufficient catalytic activity and stability and high cost are the barriers for Pt-based electrocatalysts in wide practical applications. Herein, a hierarchically porous PtNi nanoframe/N-doped graphene aerogel (PtNiNF-NGA) electrocatalyst with outstanding performance toward methanol oxidation reaction (MOR) in acid electrolyte has been developed via facile tert-butanol-assisted structure reconfiguration. The ensemble of high-alloying-degree-modulated electronic
structure and correspondingly the optimum MOR reaction pathway, the structure superiorities of hierarchical porosity, thin edges, Pt-rich corners, and the anchoring effect of the NGA, endow the PtNiNF-NGA with both prominent electrocatalytic activity and stability. The mass and specific activity (1647 mAmgPt -1, 3.8 mAcm-2) of the PtNiNF-NGA are 5.8 and 7.8 times higher than those of commercial Pt/C. It exhibits exceptional stability under a 5-hour chronoamperometry test and 2200-cycle cyclic voltammetry scanning.

Permalink: https://www.hzdr.de/publications/Publ-32527
Publ.-Id: 32527


Didier L. BOURLÈS (1955-2021), the 5 MV cosmogenic rock star

Braucher, R.; Blard, P.-H.; Brown, E. T.; Carcaillet, J.; Lebatard, A.-E.; Siame, L.; Simon, Q.; Thouveny, N.; Aumaître, G.; Bard, E.; Carretier, S.; Cornu, S.; Fink, D.; Finkel, R.; German, C.; Godard, V.; Hamelin, B.; Hofmann, F. M.; Jomelli, V.; Keddadouche, K.; Kurz, M. D.; Palacios, D.; Measures, C.; Merchel, S.; Regard, V.; Schimmelpfennig, I.; von Blanckenburg, F.; Zerathe, S.

paper without abstract

Permalink: https://www.hzdr.de/publications/Publ-32526
Publ.-Id: 32526


60Fe and 244Pu deposited on Earth constrain the r-process yields of recent nearby supernovae

Wallner, A.; Froehlich, M. B.; Hotchkis, M. A. C.; Kinoshita, N.; Paul, M.; Martschini, M.; Pavetich, S.; Tims, S. G.; Kivel, N.; Schumann, D.; Honda, M.; Matsuzaki, H.; Yamagata, T.

Half of the chemical elements heavier than iron are produced by the rapid neutron capture process (r-process). The sites and yields of this process are disputed, with candidates including some types of supernovae (SNe) and mergers of neutron stars. We search for two isotopic signatures in a sample of Pacific Ocean crust: 60Fe (half-life 2.6 million years, Myr), predominantly produced in massive stars and ejected in SN explosions; and 244Pu, (half-life 80.6 Myr) produced solely in r-process events. We detect two distinct influxes of 60Fe to Earth in the last 10 Myr and accompanying lower quantities of 244Pu. The 244Pu/60Fe influx ratios are similar for both events. The 244Pu influx is lower than expected if SNe dominate r-process nucleosynthesis, implying some contribution from other sources.

Keywords: r process; Supernova; interstellar medium; accelerator mass spectrometry; deep-sea archive; 60Fe; 244Pu

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-32525
Publ.-Id: 32525


Metal-induced progressive alteration of conducting states in memristors for implementing an efficient analog memory: a DFT-supported experimental approach

Das, D.; Barman, A.; Sarkar, P. K.; Rajput, P.; Jha, S. N.; Hübner, R.; Kanjilal, D.; Johari, P.; Kanjilal, A.

Advancement of the memristor-based artificial synapse (AS) is urgently needed for rapid progress in neuromorphic devices. The precise structural and chemical engineering of metal oxide layers by metal dopants (Ni) is presented as an innovative way to set off a decent performance of the AS. An ON/OFF ratio of 103 as well as data retention and endurance capabilities of 104 s and 103 cycles, respectively, are achieved. With these properties, the symmetric alteration in conductance states, short-term plasticity (STP) and long-term plasticity (LTP) are realized within the same device, and compared with the reported values to establish its excellent cognitive behavioural ability. Our combined experimental and the DFT-based first-principles calculation results reveal that the rational designing of AS using metal cations (Ni) can promote an ultra-low-power of about 2.55 fJ per pulse (lower than human brain about 10 fJ per pulse) for STP, promising for next-generation smart memory devices. Here, Ni endorses strong electronic localization, which in turn familiarizes trap states within the forbidden energy gap and improves short-term memory loss. Further, it modifies the local electrostatic barriers to stimulate modulatory action (as commonly observed in the mammalian brain) for LTP. Overall, this work provides a novel pathway to overcome the technological bottleneck.

Permalink: https://www.hzdr.de/publications/Publ-32523
Publ.-Id: 32523


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