Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

"Online First" included
Without submitted and only approved publications
Only approved publications

35836 Publications

Neutron Capture Cross Section for 10Be

Volknandt, M.; Eberhardt, K.; Endres, A.; Erbacher, P.; Fix, M.; Göbel, K.; Heftrich, T.; Heinitz, S.; Hrivula, E.; Junghans, A.; Käppeler, F.; Kivel, N.; Langer, C.; Mengoni, A.; Reifarth, R.; Schmidt, S.; Schumann, D.; Thomas, B.; Veltum, D.; Weigand, M.; Wiehl, N.; Wolf, C.

The determination of the involved reaction cross sections is essential for the understanding of how the big bang nucleosynthesis and nuclear reactions in stars contribute to the observed abundances. One of those, which has not been measured so far, is the 10Be(n,γ) cross section.

A 10BeO sample, provided by PSI Villigen, was irradiated in a cyclic activation at the TRIGA reactor in Mainz. The characteristic γ-rays following the decay of 11Be were measured using LaBr3 scintillation detectors. The thermal neutron cross section and the resonance integral were experimentally determined for the first time.

Publ.-Id: 32291

80Se(n,γ) cross-section measurement at CERN n_TOF

Babiano-Suarez, V.; Aberle, O.; Alcayne, V.; Amaducci, S.; Andrzejewski, J.; Audouin, L.; Bacak, M.; Balibrea-Correa, J.; Barbagallo, M.; Bennett, S.; Berthoumieux, E.; Bosnar, D.; Brown, A. S.; Busso, M.; Caamaño, M.; Caballero, L.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Casanovas, A.; Cerutti, F.; Chiaveri, E.; Colonna, N.; Cortés, G. P.; Cortés-Giraldo, M. A.; Cosentino, L.; Cristallo, S.; Damone, L. A.; Davies, P. J.; Diakaki, M.; Dietz, M.; Domingo-Pardo, C.; Dressler, R.; Ducasse, Q.; Dupont, E.; Durán, I.; Eleme, Z.; Fernández-Domíngez, B.; Ferrari, A.; Ferro-Gonçalves, I.; Finocchiaro, P.; Furman, V.; Garg, R.; Gawlik, A.; Gilardoni, S.; Göbel, K.; González-Romero, E.; Guerrero, C.; Gunsing, F.; Heinitz, S.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Jiri, U.; Junghans, A.; Kadi, Y.; Käppeler, F.; Kimura, A.; Knapová, I.; Kokkoris, M.; Kopatch, Y.; Krticka, M.; Kurtulgil, D.; Ladarescu, I.; Lederer-Woods, C.; Lerendegui-Marco, J.; Lonsdale, S.-J.; Macina, D.; Manna, A.; Martínez, T.; Masi, A.; Massimi, C.; Mastinu, P. F.; Mastromarco, M.; Maugeri, E.; Mazzone, A.; Mendoza, E.; Mengoni, A.; Michalopoulou, V.; Milazzo, P. M.; Millán-Callado, M. A.; Mingrone, F.; Moreno-Soto, J.; Musumarra, A.; Negret, A.; Ogállar, F.; Oprea, A.; Patronis, N.; Pavlik, A.; Perkowski, J.; Petrone, C.; Piersanti, L.; Pirovano, E.; Porras, I.; Praena, J.; Quesada, J. M.; Ramos Doval, D.; Reifarth, R.; Rochman, D.; Rubbia, C.; Sabaté-Gilarte, M.; Saxena, A.; Schillebeeckx, P.; Schumann, D.; Sekhar, A.; Smith, A. G.; Sosnin, N.; Sprung, P.; Stamatopoulos, A.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A. E.; Tassan-Got, L.; Thomas, B.; Torres-Sánchez, P.; Tsinganis, A.; Urlass, S.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vescovi, D.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Woods, P. J.; Wright, T. J.; Žugec, P.

Radiative neutron capture cross section measurements are of fundamental importance for the study of the slow neutron capture (s-) process of nucleosynthesis. This mechanism is responsible for the formation of most elements heavier than iron in the Universe. Particularly relevant are branching nuclei along the s-process path, which are sensitive to the physical conditions of the stellar environment. One such example is the branching at 79Se (3.27 × 105 y), which shows a thermally dependent β-decay rate. However, an astrophysically consistent interpretation requires also the knowledge of the closest neighbour isotopes involved. In particular, the 80Se(n,γ) cross section directly affects the stellar yield of the "cold" branch leading to the formation of the s-only 82Kr. Experimentally, there exists only one previous measurement on 80Se using the time of flight (TOF) technique. However, the latter suffers from some limitations that are described in this presentation. These drawbacks have been significantly improved in a recent measurement at CERN n TOF. This contribution presents a summary of the latter measurement and the status of the data analysis.


Publ.-Id: 32290

Radiotherapy enhances uptake and efficacy of 90Y-cetuximab: A preclinical trial

Dietrich, A.; Andreeff, M.; Koi, L.; Bergmann, R.; Schubert, M.; Schreiner, L.; Löck, S.; Sihver, W.; Freudenberg, R.; Hering, S.; Pietzsch, H.-J.; Steinbach, J.; Kotzerke, J.; Baumann, M.; Krause, M.

Background and purpose

Systemic molecular radiotherapy utilizes internal irradiation by radionuclide-labeled tumor-targeting agents with the potential to destroy (micro-)metastases. However, doses that are applicable in solid tumors do not reach the levels nessecary for tumor control. Thus, the combination of molecular and external radiotherapy is a promising treatment strategy, as enhanced tumor doses can be delivered with and without minor overlapping toxicities. Here, we combined a 90Y-labeled anti-EGFR antibody (Cetuximab) with clinically relevant fractionated radiotherapy in a preclinical trial using head and neck squamous cell carcinoma xenograft tumors.
Materials and methods

To model 90Y-Cetuximab uptake for treatment schedule optimization, FaDu-bearing mice were injected with near-infrared-labeled-Cetuximab at different time points during radiotherapy with differing doses. Cetuximab uptake was longitudinally followed by in vivo-optical imaging. Tumor control probability experiments with fractionated radiotherapy (30 fx, 6 weeks, 8 dose groups/ arm) in combination with 90Y-Cetuximab were performed to test the curative potential.


Imaging of near-infrared-labeled-Cetuximab uptake revealed that low to moderate external beam doses can enhance antibody uptake. Using the optimized schedule, combination of molecular and external radiotherapy using 90Y-Cetuximab at a dose that did not result in permanent tumor inactivation in previous experiments, led to substantially increased tumor control compared to radiotherapy alone.

Our results indicate that combination of radiolabeled therapeutics with clinically relevant fractionated radiotherapy has a remarkable potential to improve curative treatment outcome. Application of some radiation dose prior to injection may improve drug uptake and enable patient stratification and treatment personalization via a corresponding PET-tracer during therapy.

Keywords: Molecular radiotherapy Combination therapy Cetuximab Preclinical imaging Radiation therapy Radioimmu

Publ.-Id: 32289

On-shot dosimetry setup for radiobiology studies on volumetric in-vivo samples with laser accelerated proton beams

Reimold, M.

Laser plasma-based accelerators promise to provide proton sources for radiobiological studies with extended possibilities compared to conventional accelerators due to short acceleration lengths, high pulse doses, high dose rates and the usage of compact magnets for beam guiding operated in pulsed mode. For the generation of radiobiological relevant proton energies, Petawatt (PW) class laser powers are required, which can be provided at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) by the DRACO laser system and the upcoming PENELOPE laser system. Both laser systems will be used to perform radiobiological in-vivo studies which require precise absolute dosimetry for three-dimensional depth-dose profiles on a millimeter scale. This presentation gives an overview of the dosimetry setup developed for radio-biological studies on volumetric samples consisting of a combination of several different detector types for on-shot dose measurement (ionization chambers, time-of-flight spectrometer), absolute calibration (radiochromic films) and spatial dose profile optimization (scintillators). Additionally, a recently developed detector system design based on scintillator emission tomography for the full reconstruction of an arbitrary proton depth profile generated by a single proton bunch will be presented. Details on the reconstruction of the 3D dose distribution inside the scintillator volume and the reverse calculation of the angularly resolved proton energy spectrum are discussed.

  • Lecture (Conference) (Online presentation)
    LaPlaSS, 18.09.2020, Salamanca/ Dresden, Spanien/ Deutschland
  • Lecture (Conference) (Online presentation)
    BLIN4, 29.06.2020, München/ Dresden, Deutschland

Publ.-Id: 32288

Beam monitoring and dosimetry for in vivo studies with laser-driven protons at Draco PW

Reimold, M.

Petawatt laser-plasma based proton sources, capable of providing multi-10 MeV proton pulses at ultra-high dose rates of 10^9 Gy/s, are unique sources for radiobiological studies of ~mm size 3D in vivo samples in the recently strongly investigated FLASH regime.
At Draco PW (HZDR), a compact and tunable pulsed power beamline is utilized for efficient beam transport and spectral filtering for dose deposition in a sample. The setup was successfully used for in vivo radiobiological studies with up to 20 Gy single shot doses as well as for accumulative multi-shot low dose (~500 mGy) schemes for %-level accuracy of dose delivery.
Regarding beam monitoring and dosimetry, the inherent fluctuations of the laser-driven source, the ultra-high dose rate and the experimental environment (pulsed power, EMP) pose challenges for established dosimetry methods.
In this presentation, we present a non-invasive scintillator-based time-of-flight spectrometer as a unique tool for single-shot online beam optimization and monitoring of laser-driven proton pulses in application experiments. Calibration of the device against established dosimeters (here radiochromic film) in combination with Monto Carlo simulations additionally allows dosimetric use, overcoming saturation issues with dose rate or linear energy transfer present in other devices.
To illustrate the suitability of the time-of-flight spectrometer as a beam monitor and absolute dosimeter for laser-based protons, the time-of-flight data of two radiobiological in vivo irradiation campaigns performed at the implemented beamline at the DRACO PW facility are presented.

Keywords: time-of-flight spectrometer

  • Lecture (Conference) (Online presentation)
    WHELMI-Meeting, 17.-18.12.2020, Dresden-Rossendorf/ Rechovot, Deutschland/ Israel
  • Lecture (Conference) (Online presentation)
    Gruppenseminar, 08.02.2021, Dresden, Deutschland
  • Lecture (Conference) (Online presentation)
    M&T Student Retreat, 01.02.2021, Dresden, Deutschland

Publ.-Id: 32287

Nanoparticle-Stabilized Perforated Lamellar Morphology in Block Copolymer/Quantum Dot Hybrids

Singh, S.; Horechyy, A.; Yadav, S.; Formanek, P.; Hübner, R.; Srivastava, R. K.; Sapra, S.; Fery, A.; Nandan, B.

We report on the surprising observation of a unique perforated lamellar (PL) morphology in a mixture of an asymmetric polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer and CdSe−CdS quantum dots (QDs). The PL morphology formed by the PS-b-P4VP/CdSe−CdS composites consisted of alternating layers of PS and P4VP, where the layer formed by the minority PS block contained cylindrical perforations of the majority P4VP block. Most interestingly, the CdSe−CdS QDs were localized exclusively in the P4VP perforations. The swelling of the bulk samples in a P4VP selective solvent also allowed the isolation of the perforated PS nanosheets, with QDs localized in the perforations, which further provided strong evidence for the formation of the unique PL morphology. The observed PL morphology was, plausibly, energetically stabilized because of the localization of QDs within the P4VP perforations, which allowed for the conformational entropy minimization of the majority P4VP block. The present work reveals possibilities for the discovery of novel hierarchical structures in block copolymer/nanoparticle composite systems and also provides new opportunities for the application of such materials in nanotechnology.

Publ.-Id: 32286

Assessment of column tray flow patterns and separation efficiencies on large-scale distillation trays

Vishwakarma, V.; Marchini, S.; Abdul Haq, S.; Schleicher, E.; Bieberle, A.; Schubert, M.; Hampel, U.

Thorough characterization of mixing behavior and separation efficiencies of large-scale distillation trays is important especially in their design phase. A precise account of the tray operation would allow modifying their mixing and mass-transfer characteristics (via design modifications) for better separation efficiencies (see design strategy in Fig. 1, left).
Fig. 1. Design strategy for distillation trays (left), and relevant data on the distributions of liquid holdup, residence time, RTD variance, and species concentration (right).
The existing literature lacks a thorough hydrodynamic description of large-scale distillation trays. Thus, the CFD studies have relied either on trivial measurements (such as those of pressure drop, liquid weeping and entrainment, visual froth height, etc.) or the available low-resolution residence time data for model validation rather than on refined data on flow path and local mixing.
Meanwhile, an extensive description of the tray hydrodynamics can be made available using the recently proposed flow profiler.1 Based on recent developments in that regard, the distributions of liquid holdup, residence time and mixing are obtained over the entire deck (see Fig. 1, right) for several gas and liquid loadings at high resolution.
The acquired data permits to predict the tray efficiency by applying models that relate liquid flow patterns with the tray performance, such as the recently proposed ‘Refined RTD (RRTD) model’ that considers the mixing behavior at intermediary tray locations.2
Eventually, experimental data on air stripping of isobutyl acetate from the aqueous solution at tray loadings same as those during the hydrodynamic experiments can be applied to validate the proposed efficiency model. An example of species concentration distribution (i.e., examined using UV spectroscopy) over the tray deck is also shown in Fig. 1 (right).

[1] Vishwakarma, V., Schleicher, E., Schubert, M., Tschofen, M. and Löschau, M., 2020. Sensor zur Vermessung von Strömungsprofilen in großen Kolonnen und Apparaten. Deutsches Patent und Markenamt, DE 10 2018 124 501.
[2] Vishwakarma, V., Schubert, M. and Hampel, U., 2019. Development of a refined RTD-based efficiency prediction model for cross-flow trays. Ind. Eng. Chem. Res., 58(8), pp.3258-3268.

  • Lecture (Conference) (Online presentation)
    Jahrestreffen der ProcessNet-Fachgruppen Fluidverfahrenstechnik und Wärme- und Stoffübertragung, 24.-26.02.2021, Online event, Germany

Publ.-Id: 32285

Experimental analysis of the hydrodynamic performance of an industrial-scale cross-flow sieve tray

Vishwakarma, V.; Abdul Haq, S.; Schleicher, E.; Schubert, M.; Hampel, U.

This work reports the hydrodynamic description of a large-scale sieve tray equipped in an air/water column mockup. The test tray accommodates a multi-probe flow profiler for simultaneous conductivity measurements. 3D liquid holdup distribution, liquid residence time distribution and effective froth height distribution are obtained at high spatiotemporal resolution for several gas and liquid loadings. The liquid flow and mixing patterns are visualized via tracer-based experiments. The methodologies used for acquiring these distributions are discussed in this work. Thorough examination of the processed experimental data reveals the hydrodynamic characteristics of an operational sieve tray for the studied loadings.

Keywords: column tray; hydrodynamics; effective froth height; 3D liquid holdup; tracer-response analysis

Related publications


  • Secondary publication expected

Publ.-Id: 32284

Nonlinear response in warm dense matter

Vorberger, J.

Talk at Hirschegg workshop "41th International Workshop on High Energy Density Physics with Intense Ion and Laser Beams"

Keywords: warm dense matter; nonlinear response; quantum Monte Carlo; Green's function

  • Lecture (Conference) (Online presentation)
    41th International Workshop on High Energy Density Physics with Intense Ion and Laser Beams, 01.-05.02.2021, Hirschegg, Austria

Publ.-Id: 32282

Nonequilibrium in general and in warm dense matter

Vorberger, J.

Talk given at CASUS

Keywords: non-equilibrium; warm dense matter; Boltzmann; kadanoff-baym; two temperature model

  • Lecture (others) (Online presentation)
    MEC Seminar at CASUS, 26.01.2021, Görlitz, Germany

Publ.-Id: 32281

The Impact of Barium Isotopes in Radiopharmacy and Nuclear Medicine – from Past to Presence

Reissig, F.; Kopka, K.; Mamat, C.

With the exception of beryllium, every alkaline earth metal is characterized by a calcimimetic behavior. Thus, in vivo biodistribution mostly occurs in form of a massive accumulation in bone tissues, consisting of hydroxyapatite to a major extent. Apart from the lightest elements beryllium and magnesium, animal studies and human studies regarding the overall in vivo behavior were carried out by using radioisotopes of the elements calcium, strontium, barium, and radium. To date, only strontium with its radioisotopes gained importance for applications in nuclear medicine, mainly for pain-reducing and palliative treatment of bone metastases. In contrast, barium isotopes can be useful imaging agents and possible diagnostic analogues for theranostic approaches. This review focuses on the characteristic and chemical behavior of barium compounds, possible radioactive barium isotopes for future applications in nuclear medicine and radiopharmacy as well as recent results regarding barium-131 as diagnostic match for radium isotopes used in targeted alpha therapy.

Keywords: Barium isotopes; bone seeker; alkaline earth metals; brachytherapy


  • Secondary publication expected from 26.05.2022

Publ.-Id: 32280

Dependence of the damage in optical metal/dielectric coatings on the energy of ions in irradiation experiments for space qualification

Pelizzo, M. G.; Corso, A. J.; Santi, G.; Hübner, R.; Garoli, D.; Doyle, D.; Lubin, P.; Cohen, A. N.; Erlikhman, J.; Favaro, G.; Bazzan, M.; Drobny, J.; Curreli, D.; Umansky, M.

Terrestrial accelerator facilities can generate ion beams which enable the testing of the resistance of materials and thin film coatings to be used in the space environment. In this work, a TiO2/Al bi-layer coating has been irradiated with a He+ beam at three different energies. The same flux and dose have been used in order to investigate the damage dependence on the energy. The energies were selected to be in the range 4-100 keV, in order to consider those associated to the quiet solar wind and to the particles present in the near-Earth space environment. The optical, morphological and structural modifications have been investigated by using various techniques. Surprisingly, the most damaged sample is the one irradiated at the intermediate energy, which, on the other hand, corresponds to the case in which the interface between the two layers is more stressed. Results demonstrate that ion energies for irradiation tests must be carefully selected to properly qualify space components.

Publ.-Id: 32279

Annual Report 2020 - Institute of Resource Ecology

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

The institute of Resource Ecology (IRE) is one of the eight institutes of the Helmholtz-Zentrum Dresden –Rossendorf (HZDR). Our research activities are mainly integrated into the program “Nuclear Waste Management, Safety and Ra-diation Research (NUSAFE)” of the Helmholtz Association (HGF) and focused on the topics “Safety of Nuclear Waste Disposal” and “Safety Research for Nuclear Reactors”. The program NUSAFE, and therefore all work which is done at IRE, belong to the research field “Energy” of the HGF.

Related publications

  • Open Access Logo Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-113 2021
    ISSN: 2191-8708, eISSN: 2191-8716


Publ.-Id: 32278

Data for: Spin-wave dynamics and symmetry breaking in an artificial spin ice

Saha, S.; Zhou, J.; Hofhuis, K.; Kakay, A.; Scagnoli, V.; Heyderman, L. J.; Gliga, S.

These data are related to the publication entitled: Spin-wave dynamics and symmetry breaking in an artificial spin ice

The archive-files.txt contains a detailed description of the files stored in the repository-files-paper.tar file.

The geometry .bmp files are also included, thus anyone can reproduce the results by using mumax3 from

Keywords: nanomagnetism; artificial spin ice; spin wave; magnetization dynamics; magnonic crystal

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-02-08
    DOI: 10.14278/rodare.799


Publ.-Id: 32277

Sub-20 nm multilayer nanopillar patterning for hybrid SET/CMOS integration: Figs. 1a, 1b and 5

Engelmann, H.-J.
Project Leader: von Borany, Johannes

Energy-filtered transmission electron microscopy (EFTEM) images of stacked Si/SiO2/Si nanopillars

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-02-09
    DOI: 10.14278/rodare.806
    License: CC-BY-4.0


Publ.-Id: 32276

Data file for manuscript on Interfacial Properties of Tridecyl Dimethyl Phosphine Oxide Adsorbed at the Surface of a Solution Drop in Hexane Saturated Air

Javadi, A.

Experimental data for paper: Interfacial Properties of Tridecyl Dimethyl Phosphine Oxide Adsorbed at the Surface of a Solution Drop in Hexane Saturated Air.

The presented data are measured dynamic surface tension of Tridecyl Dimethyl Phosphine Oxide in water against air and alkane vapors, by profile analysis tensiometry. It also includes data analysis standard deviation from Young-Laplace fitting, and theoretical analysis illustrating isotherm of adsorption.

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-02-08
    DOI: 10.14278/rodare.804


Publ.-Id: 32274

Data File for Drop Size Dependence of the Apparent Surface Tension of Aqueous Solutions in Hexane Vapor

Javadi, A.

Experimental data file for Paper on "Drop Size Dependence of the Apparent Surface Tension of Aqueous Solutions in Hexane Vapor as Studied by Drop Profile Analysis Tensiometry".

These data are measured dynamic surface tension and variations of deviations from Young Laplace fitting, of different drop size of surfactants solution Tridecyl dimethyl phosphine oxide C13DMPO and Oxyethylated alcohol С14ЕО8 in water against air and hexane vapor. 

Related publications

  • Software in the HZDR data repository RODARE
    Publication date: 2021-02-08
    DOI: 10.14278/rodare.802


Publ.-Id: 32273

Characterization of lithium ion battery recycling processes and estimation of liberation efficiency of electrodes using automated mineralogy

Vanderbruggen, A.; Hayagan, N. L.; Bachmann, K.; Rudolph, M.

Lithium-ion batteries (LIBs) are currently one of the most important electrochemical energy storage devices, powering electronic mobile devices and electric vehicles. Growing global demands for Co, Mn, Ni, Li, and graphite which are all used and present in LIBs as energy storage added difficulties to the already deficit and imbalance supply of sources of raw materials worldwide, which resulted to supply risks, price fluctuations and monopoly of market. In fact, Co and natural graphite are listed as critical raw materials (CRMs) in Europe since 2010 and Mn, and Li are on the boundary of criticality. While recycling is identified as a solution to potentially reduce the gap between the demand and supply. Recycling of lithium ion battery (LIB) has attracted a lot of attention in the recent years and focuses primarily on valuable metals such as cobalt, nickel and lithium. During the recycling processes, considerable amount of the components are lost like electrolyte, separator or graphite. For instance, graphite can either be slagged-off or consumed as a reductant agent during pyrometallurgical treatment. Some other loses are due to a lack of liberation of the targeted particles, elements such as Co are lost in the coarse fractions and a not recovered in the right product. Hence, there is a need to find innovative and comprehensive LIB recycling operations.
For understanding and be able to quantify the loses and recycling process efficiency a deeper characterization is required. This research proposes a new characterization method based on automated mineralogy. In this study, the particles morphologies (size, composition and phases associations) are analysed. The liberation of active materials from electrodes is quantified by comparing two recycling processes: mechanical and thermochemical-mechanical. The mechanical route operates with an impact shear crusher while for the thermomechanical operation the batteries were vacuum pyrolyzed at 500-650oC before to be crushed. The black mass, fraction below 1 mm from the recycling processes, were classified in 4 size fractions based on the particles size distribution. Each fraction was characterized by various analytical methods, including X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Atomic Absorption Spectrometry (AAS) and SEM-based automated mineralogy. The latter consists in the combination of a scanning electron microscopy (SEM) image analysis and energy dispersive X-ray spectroscopy (EDS). It is a powerful and well-known method for primary material characterization; however, it has not yet been applied to secondary material such as black mass, which is a challenging material to analyse due fine alloys particles and to the lack of an existing dedicated database.
In this research, a database for battery characterization is also aimed aside from the determination of the liberation efficiency of the processes employed. Furthermore, a unique procedure was used in preparing the grain mounts for SEM-EDS analysis. Here, iodoform is added to modify the grey level of resin, which improves the contrast with the carbon phases. This technic allows the quantification of the carbon phases which is also a limitation of XRF and XRD aside from the fact that these methods cannot provide images for qualitative evaluation. This study showed that the thermo-mechanical process liberates more active particles from the foils than only a mechanical process. For both processes, a liberation selectivity of the electrode foils was observed. Cu foil is better liberated than Al foils. By consequence, most of the graphite particles are concentrated in the <63μm fraction. However, it was
found that the process type has different effects on Al foil liberation. The thermomechanical process liberates more metal oxides from the Al foil than only mechanical process, but Al breakage is more affected by thermal treatment, which creates finer Al particles, which can be problematic for further hydrometallurgy routes.

Keywords: Recycling; Lithium ion battery; Automated mineralogy; critical raw material; Graphite

Publ.-Id: 32271

Highlight selection of radiochemistry and radiopharmacy developments by editorial board (January-June 2020).

Al-Qahtani, M.; Behe, M.; Bormans, G.; Carlucci, G.; Dasilva, J.; Decristoforo, C.; Elsinga, P.; Kopka, K.; Li, X.; Mach, R.; Middel, O.; Passchier, J.; Patt, M.; Penuelas, I.; Rey, A.; Scott, P.; Todde, S.; Toyohara, J.; Vugts, D.

Background: The Editorial Board of EJNMMI Radiopharmacy and Chemistry releases a biyearly highlight commentary to describe trends in the field.
Results: This commentary of highlights has resulted in 19 different topics selected by each member of the Editorial Board addressing a variety of aspects ranging from novel radiochemistry to first in man application of novel radiopharmaceuticals.
Conclusion: Trends in radiochemistry and radiopharmacy are highlighted demonstrating the progress in the research field being the scope of EJNMMI Radiopharmacy and Chemistry.

Publ.-Id: 32266

Curvilinear magnetism: fundamentals and applications

Makarov, D.

Extending 2D structures into 3D space has become a general trend in multiple disciplines including electronics, photonics, and magnetics. This approach provides means to enrich conventional or to launch novel functionalities by tailoring geometrical curvature and 3D shape. We study 3D curved magnetic thin films and nanowires where new fundamental effects emerge from the interplay of the geometry of an object and topology of a magnetic sub-system [1-4]. The lack of an inversion symmetry and the emergence of a curvature induced effective anisotropy and DMI are characteristic of curved surfaces, leading to curvature-driven magnetochiral responses and topologically induced magnetization patterning [5-7]. 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. The application potential of 3D-shaped magnetic thin films is currently being explored as mechanically shapeable magnetic field sensors [8] for automotive applications, magnetoelectrics for memory devices, spin-wave filters, high-speed racetrack memory devices as well as on-skin interactive electronics [9-11]. The magnetosensitive smart skins allow digitizing the bodily motion and offer new means of touchless manipulation of virtual objects based on the interaction with magnetic stray fields of small permanent magnets [9,11] but also with geomagnetic field [10]. The fundamentals as well as application relevant aspects of curvilinear magnetism will be covered in this presentation.

[1] R. Streubel et al., Magnetism in curved geometries. J. Phys. D: Appl. Phys. (Review) 49, 363001 (2016).
[2] D. Sander et al., The 2017 magnetism roadmap. J. Phys. D: Appl. Phys. (Review) 50, 363001 (2017).
[3] O. M. Volkov et al., Experimental observation of exchange-driven chiral effects in curvilinear magnetism. Phys. Rev. Lett. 123, 077201 (2019).
[4] D. Sheka et al., Nonlocal chiral symmetry breaking in curvilinear magnetic shells. Communications Physics 3, 128 (2020)
[5] V. Kravchuk et al., Multiplet of Skyrmion states on a curvilinear defect: Reconfigurable Skyrmion lattices. Phys. Rev. Lett. 120, 067201 (2018)
[6] O. Pylypovskyi et al., Chiral Skyrmion and Skyrmionium States Engineered by the Gradient of Curvature. Phys. Rev. Appl. 10, 064057 (2018)
[7] O. Pylypovskyi et al., Coupling of chiralities in spin and physical spaces: The Möbius ring as a case study. Phys. Rev. Lett. 114, 197204 (2015)
[8] D. Makarov et al., Shapeable magnetoelectronics. Appl. Phys. Rev. (Review) 3, 011101 (2016).
[9] G. S. Cañón Bermúdez et al., Magnetosensitive e-skins with directional perception for augmented reality. Science Advances 4, eaao2623 (2018).
[10] G. S. Cañón Bermúdez et al., Electronic-skin compasses for geomagnetic field driven artificial magnetoception and interactive electronics. Nature Electronics 1, 589 (2018).
[11] J. Ge et al., A bimodal soft electronic skin for tactile and touchless interaction in real time. Nature Communications 10, 4405 (2019).

Keywords: flexible electronics; curvilinear magnetism; magnetosensitive smart skins

  • Lecture (others) (Online presentation)
    Seminar at the University of Kiel, 11.02.2021, Kiel, Germany

Publ.-Id: 32265

Mechanisms of pyrite biodepression with Acidithiobacillus ferrooxidans in seawater flotation

San Martin, F.; Kracht, W.; Vargas, T.; Rudolph, M.

It has been shown that bacterium Acidithiobacillus ferrooxidans can be used to depress pyrite in seawater flotation at natural pH, which opens the possibility for its use as an alternative to lime to depress pyrite in copper sulfide flotation. In order to have a better understanding of the mechanisms involved in pyrite depression with A. ferrooxidans, different kind of experiments were carried out, including, contact angle, attachment kinetics, and streaming potential measurements. All these experiments were carried out in seawater. Biodepression of pyrite was improved by increasing the pH from 4 to 8, with a decrease in recovery from 92% to 36%. This increase in depressing capability was accompanied by an increase in attachment density of bacteria on pyrite, from bacteria/g to bacteria/g at pH 4 and 8, respectively. These results suggest that the mechanism of depression is related to the attachment of bacteria to the pyrite surface. The streaming potential measurements showed that both bacteria and pyrite were negatively charged at pH 8. This indicates that electrostatic forces are mainly repulsive, therefore other forces cause the attachment of bacteria to the mineral. The contact angle of pyrite conditioned with seawater at pH 8 was 16, which increased to 54 when collector (sodium isopropyl xanthate) was added, indicating an increase in hydrophobicity. Nevertheless, when pyrite was previous conditioned with bacteria, the contact angle increased only to 44 when collector was added. Thus, the collector has a lower influence in the hydrophobicity of pyrite when the mineral has interacted with bacteria A. ferrooxidans.

Keywords: Flotation; Seawater; Pyrite; Biodepression; Acidithiobacillus ferrooxidans


Publ.-Id: 32264

Advanced Analysis of Bubble Columns: Comparison of Euler/Lagrange Simulations and Experiments under CO2 chemisorption conditions

Taborda, M. A.; Kipping, R.; Hampel, U.; Sommerfeld, M.

The chemical absorption reaction of CO2 in a circular bubble column reactor was simulated with an Euler/Lagrange CFD method and results were compared with data from a laboratory scale bubble column. The experimental data comprises gas holdup and bubble size distributions obtained with ultrafast X-ray tomography and hydroxide ion conversion obtained with a wire-mesh sensor. Large Eddy Simulation (LES) is used for calculating the fluid flow and modelling the turbulence in the continuous phase, considering the effect of sub-grid-scale (SGS) turbulence on bubble motion, and also SGS turbulence modification by bubbles. Lagrangian bubble tracking is conducted considering all relevant forces, bubble oscillation via stochastic generation of eccentricity and motion angle and consequently non-steady mass transfer via a dynamic Sherwood number. The comparison of experimental and simulation results shows very good agreement for the given data.

Keywords: Euler/Lagrange approach; bubble dynamics model; reactive two-phase flow; dynamic Sherwood number; wire-mesh sensor; ultrafast X-ray computed tomography

Related publications


Publ.-Id: 32261

Study of the parameter dependence of laser-accelerated protons from a hydrogen cluster source

Aurand, B.; Schwind, K. M.; Toncian, T.; Aktan, E.; Cerchez, M.; Lessmann, L.; Mannweiler, C.; Prasad, R.; Khoukaz, A.; Willi, O.

We present a study on laser-driven proton acceleration from a hydrogen cluster target. Aiming for the optimisation of the proton source, we performed a detailed parametric scan of the interaction conditions by varying different laser and the target parameters. While the underlying process of a Coulomb-explosion delivers moderate energies, in the range of 100 s of keV, the use of hydrogen as target material comes with the benefit of a debris-free, single-species proton acceleration scheme, enabling high repetition-rate experiments, which are very robust against shot-to-shot fluctuations.


Publ.-Id: 32260

Direct laser acceleration of electrons assisted by strong laser-driven azimuthal plasma magnetic fields

Gong, Z.; Mackenroth, F.; Wang, T.; Yan, X. Q.; Toncian, T.; Arefiev, A. V.

A high-intensity laser beam propagating through a dense plasma drives a strong current that robustly sustains a strong quasistatic azimuthal magnetic field. The laser field efficiently accelerates electrons in such a field that confines the transverse motion and deflects the electrons in the forward direction. Its advantage is a threshold rather than resonant behavior, accelerating electrons to high energies for sufficiently strong laser-driven currents. We study the electron dynamics via a test-electron model, specifically deriving the corresponding critical current density. We confirm the model's predictions by numerical simulations, indicating energy gains two orders of magnitude higher than achievable without the magnetic field.


Publ.-Id: 32259

Application of Laser-Driven Capacitor-Coil to Target Normal Sheath Acceleration

Morita, H.; Arefiev, A.; Toncian, T.; Jorge Santos, J.; Golovin, D.; Shokita, S.; Mori, T.; Fai Farley Law, K.; Li, H.; Takizawa, R.; Matsuo, K.; Morace, A.; Yogo, A.; Fujioka, S.

A laser-driven accelerator generates protons with tens of MeV in energy by a compact, strong, and transient accelerating electric field produced as a result of laser–plasma interactions at relativistic intensities. In previous studies, two- and three-dimensional particle-in-cell simulations revealed that the application of a kT-level axial magnetic field results in an enhancement of proton acceleration via the target normal sheath acceleration mechanism due to reduced lateral electron divergence and improved electron heating efficiency. An experimental investigation of this scheme on the GEKKO-XII and the LFEX facilities found that the number and maximum energy of the accelerated protons decreased with increasing the temporal delay between the pulse driving the external magnetic-field and the pulse accelerating the protons, contrary to the theoretical and numerical expectations. We identify sources responsible for the degradation of the proton beam performance and we propose an alternative experimental setup to mitigate the degradation in future experiments.


Publ.-Id: 32258

Generation of focusing ion beams by magnetized electron sheath acceleration

Weichman, K.; Santos, J. J.; Fujioka, S.; Toncian, T.; Arefiev, A. V.

We present the first 3D fully kinetic simulations of laser driven sheath-based ion acceleration with a kilotesla-level applied magnetic field. The application of a strong magnetic field significantly and beneficially alters sheath based ion acceleration and creates two distinct stages in the acceleration process associated with the time-evolving magnetization of the hot electron sheath. The first stage delivers dramatically enhanced acceleration, and the second reverses the typical outward-directed topology of the sheath electric field into a focusing configuration. The net result is a focusing, magnetic field-directed ion source of multiple species with strongly enhanced energy and number. The predicted improvements in ion source characteristics are desirable for applications and suggest a route to experimentally confirm magnetization-related effects in the high energy density regime. We additionally perform a comparison between 2D and 3D simulation geometry, on which basis we predict the feasibility of observing magnetic field effects under experimentally relevant conditions.


Publ.-Id: 32257

A laser-driven droplet source for plasma physics applications

Aurand, B.; Aktan, E.; Schwind, K. M.; Prasad, R.; Cerchez, M.; Toncian, T.; Willi, O.

In this paper, we report on the acceleration of protons and oxygen ions from tens of micrometer large water droplets by a high-intensity laser in the range of 1020 W/cm2. Proton energies of up to 6 MeV were obtained from a hybrid acceleration regime between classical Coulomb explosion and shocks. Besides the known thermal energy spectrum, a collective acceleration of oxygen ions of different charge states is observed. 3D PIC simulations and analytical models are employed to support the experiential findings and reveal the potential for further applications and studies.


Publ.-Id: 32256

A new approach to monitor 13C-targets degradation in situ for 13C(α,n)16O cross-section measurements at LUNA

Ciani, G. F.; Csedreki, L.; Balibrea-Correa, J.; Best, A.; Aliotta, M.; Barile, F.; Bemmerer, D.; Boeltzig, A.; Broggini, C.; Bruno, C. G.; Caciolli, A.; Cavanna, F.; Chillery, T.; Colombetti, P.; Corvisiero, P.; Davinson, T.; Depalo, R.; Di Leva, A.; Di Paolo, L.; Elekes, Z.; Ferraro, F.; Fiore, E. M.; Formicola, A.; Fülöp, Z.; Gervino, G.; Guglielmetti, A.; Gustavino, C.; Gyürky, G.; Imbriani, G.; Junker, M.; Kochanek, I.; Lugaro, M.; Marigo, P.; Masha, E.; Menegazzo, R.; Mossa, V.; Pantaleo, F. R.; Paticchio, V.; Perrino, R.; Piatti, D.; Prati, P.; Schiavulli, L.; Stöckel, K.; Straniero, O.; Szücs, T.; Takács, M. P.; Terrasi, F.; Trezzi, D.; Zavatarelli, S.

Direct measurements of reaction cross-sections at astrophysical energies often require the use of solid targets able to withstand high ion beam currents for extended periods of time. Thus, monitoring target thickness, isotopic composition, and target stoichiometry during data taking is critical to account for possible target modifications and to reduce uncertainties in the final cross-section results. A common technique used for these purposes is the Nuclear Resonant Reaction Analysis (NRRA), which however requires that a narrow resonance be available inside the dynamic range of the accelerator used. In cases when this is not possible, as for example the 13C(𝛼,n)16O reaction recently studied at low energies at the Laboratory for Underground Nuclear Astrophysics (LUNA) in Italy, alternative approaches must be found. Here, we present a new application of the shape analysis of primary γ rays emitted by the 13C(p,𝛾)14N radiative capture reaction. This approach was used to monitor 13C target degradation in situ during the 13C(𝛼,n)16O data taking campaign. The results obtained are in agreement with evaluations subsequently performed at Atomki (Hungary) using the NRRA method. A preliminary application for the extraction of the 13C(α,n)16O reaction cross-section at one beam energy is also reported.

Publ.-Id: 32255

Data for: The surface expression of hydrocarbon seeps characterized by satellite image spectral analysis and rock magnetic data (Falcon basin, western Venezuela)

de La Rosa, R.; Aldana, M.; Costanzo-Alvarez, V.; Yepez, S.; Amon, C.

This work integrates satellite image spectral analyses with rock magnetic and geochemical data (i.e., mass-specific magnetic susceptibility χ, saturation isothermal remanent magnetization SIRM, analysis of SIRM acquisition curves, absorption spectro-radiometry, and X-ray diffraction analyses). The target area was an oil-prospective region in northwestern Venezuela (Falcon Basin) swarmed by hydrocarbon seeps. The study's main goal was to depict the spatial extension and vertical reach of the hydrocarbon-mediated alteration produced by these seeps and gain some knowledge about the processes involved in the subsequent mineral changes.

The dataset is composed of spreadsheets, compressing field samples data including their locations. Also, a database is presented with data from profiles extracted from the results of multispectral image processing and laboratory data of rock magnetism. 

Keywords: Satellite remote sensing; Spectral images; Spectral signature; Hydrocarbon seeps; Hydrocarbon- induced diagenesis; Rock magnetism; Weathered sequence; Two-Step Cluster Analysis

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-01-28
    DOI: 10.14278/rodare.769


Publ.-Id: 32253

The application of surface exposure dating method in case of Veliki vrh rockfall (Karavanke Mountains, Slovenia)

Mrak, I.; Merchel, S.; Braucher, R.; Benedetti, L.; Finkel, R. C.; Bourlès, D.

The use of terrestrial cosmogenic nuclides (TCN) has revolutionized Earth surface sciences over the last decade by their capacity to quantify geological surface processes. The uniqueness of these nuclides lies in their property of being produced in the top few meters of the lithosphere during exposure to cosmic radiation. There are various types of application of surface exposure dating such as chronological constraints on the timing and rates of environmental changes (glacial history, erosion) and hazard recurrence frequency (landslides and seismic activity). The method was used also in the case of Veliki vrh rockfall located in Karavanke Mountains (Slovenia). There are no reliable historical data about the rockfall event beside the oral heritage in form of a fairytale describing the catastrophic falling of rocks over the settlement in the valley, forcing the survivors to establish a new settlement (Tržic) further downstream. However, there are numerous written records about a historic rockfall (induced by an earthquake) taking place about 46 km away at Dobratsch, Carinthia on 25th January 1348 thus; it seems very likely that the same earthquake triggered both rockfalls. Surface exposure dating method has been applied on samples taken from the fresh bedrock and big blocks obviously originating from the Veliki vrh rockfall and the results are confirming our
hypothesis. They have also importantly improved geomorphologic interpretation of the area.

Keywords: AMS; cosmogenic radionuclide; rockfall; earthquake; dating

  • Lecture (Conference)
    Association of American Geographers 2011 Annual Meeting, 10.-16.04.2011, Seattle, Washington, USA

Publ.-Id: 32252

Lipase At water air intereface data HZDR TUB 2018-2020

Javadi, A.

Dynamic surface tension and competitive adsorption of Lipase enzyme and surfactants at water air interface.

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-01-28
    DOI: 10.14278/rodare.771
    License: CC-BY-4.0


Publ.-Id: 32251

alpaka, LLAMA & Vc: An ecosystem for performance portable parallelism

Stephan, J.

This talk covers the alpaka ecosystem for performance portable parallel programming in HPC and simulation environments. It focuses on alpaka, LLAMA and Vc, their interactions with each other and their impact on the C++ programming language.

Keywords: alpaka; LLAMA; Vc; C++; heterogeneous programming; portability; HPC; parallel programming

  • Open Access Logo Lecture (others) (Online presentation)
    7th MT Meeting, 01.-03.02.2021, Hamburg, Deutschland

Publ.-Id: 32250

Dataset for: Flow morphologies in straight and bent horizontal pipes (uncalibrated measurement files)

Döß, A.; Schubert, M.; Wiedemann, P.; Schleicher, E.; Hampel, U.

This data set is a supplementory to 'Dataset for: Flow morphologies in straight and bent horizontal pipes'. In addition to the void files (.v) given in the primary data sets we provide:

- Underlying uncalibrated measurements files (.dat, .dati)
- .log files for the corresponding .v-files
- Calibration measurements
- Geometry files for the used Wire-mesh sensors

Keywords: Flow morphologies; Horizontal Two-phase flow; Wire-mesh sensor; TERESA

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-01-29
    DOI: 10.14278/rodare.785


Publ.-Id: 32249

Die Bedeutung des Elementes Barium in der Nuklearmedizin

Reissig, F.; Kopka, K.; Mamat, C.

Von Erdalkalimetallionen außer Beryllium ist bekannt, dass sie ein calcimimetisches Verhalten zeigen. Damit ist ihr Schicksal in vivo vorgezeichnet, das in einem beträchtlichen Maße durch den Einbau in Knochengewebe, welches zum Hauptteil aus Hydroxylapatit besteht, charakterisiert ist. In diesem Sinne wurde auch die Verwendung von Radionukliden dieser Elemente als Knochensucher forciert. Mit Ausnahme von Beryllium und Magnesium wurden Tierexperimente und Humananwendungen mit Radionukliden von Calcium, Strontium, Barium und Radium durchgeführt, wobei bis heute lediglich Strontium und Radium, in der Hauptsache als Therapienuklide zur palliativen Behandlung von Knochenmetastasen, Eingang in nuklearmedizinische Routineanwendungen gefunden haben. In diesem Übersichtsartikel werden die Radionuklide des Bariums vorgestellt, sowie deren Herstellung und Verwendung. Aktuelle Forschungsergebnisse mit Radionukliden des Bariums in Radiopharmazie und Nuklearmedizin werden präsentiert.

Keywords: Bariumisotope; Knochensucher; Radium


  • Secondary publication expected from 16.06.2022

Publ.-Id: 32246

Data for: Single-step, High Pressure, and Two-Step Spark Plasma Sintering of UO2 nanopowders

de Bona, E.

Three different Spark Plasma Sintering (SPS) treatments were applied to highly sinteractive, near-stoichiometric UO2.04 nanocrystalline (5 nm) powders produced by U(IV) oxalate hydrothermal decomposition at 170 °C. The sintering conditions for reaching 95 % Theoretical Density (TD) in regular SPS, high pressure SPS (HP-SPS), and, for the first time, two-step SPS (2S-SPS), were determined. Densification to 95 % TD was achieved at 1000 °C in regular SPS (70 MPa applied pressure), 660 °C in HP-SPS (500 MPa), and 650-550 °C in 2S-SPS (70 MPa). With the goal of minimising the grain growth during densification, the sintering treatments were optimised to favour densification over coarsening, and the final microstructures thus obtained are compared. Equally dense UO2 samples of different grain sizes, ranging from 3.08 µm to 163 nm, were produced. Room-temperature oxidation of the powders could not be avoided due to their nanometric dimensions, and a final annealing treatment was designed to reduce hyperstoichiometric samples to UO2.00.

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-01-08
    DOI: 10.14278/rodare.498
    License: CC-BY-1.0


Publ.-Id: 32243

Validation of an LC-MS/MS method to quantify the new TRPC6 inhibitor SH045 (larixyl N-methylcarbamate) and its application in an exploratory pharmacokinetic study in mice

Chai, X.-N.; Ludwig, F.-A.; Müglitz, A.; Schaefer, M.; Yin, H.-Y.; Brust, P.; Regenthal, R.; Krügel, U.

TRPC6 (transient receptor potential cation channels; canonical subfamily C, member 6) are widespread localized in mammalian organs like kidney and lung and associated with progressive proteinuria and pathophysiological pulmonary alterations like reperfusion edema or lung fibroses. However, the understanding of TRPC6 channelopathies is still at the beginning. Recently, by chemical diversification of (+)-larixol originating from Larix decidua resin traditionally used for inhalation, its methyl carbamate congener, named SH045, was obtained and identified in functional assays as highly potent, subtype-selective inhibitor of TRPC6. To pave the way for use of SH045 in animal disease models we aimed to develop a capable bioanalytical method and to provide exploratory pharmacokinetic data for this promising derivative. According to international guidelines, a robust and selective LC-MS/MS method based on MRM detection in positive ion mode was established and validated for quantification of SH045 in mice plasma, whereby linearity and accuracy were demonstrated for the range of 2-1600 ng/mL.
Applying this method, the plasma concentration time course of SH045 following single intraperitoneal administration (20 mg/kg body weight) revealed a rather short half-life of 1.3 hours. However, the pharmacological profile of SH045 is promising as five hours after administration plasma levels still remained sufficiently higher than published low nanomolar IC50 values.
Summarizing, the LC-MS/MS quantification method and exploratory pharmacokinetic data provide important prerequisites for experimental pharmacological TRPC6 modulation and translational treatment of TRPC6 channelopathies.

Keywords: channelopathies; larixol; labdane; LC-MS/MS; mice; pharmacokinetics; SH045; TRP channels; TRPC6 inhibitor

Publ.-Id: 32242

Development of a ghrelin receptor inverse agonist for positron emission tomography

Bergmann, R.; Chollet, C.; Els-Heindl, S.; Ullrich, M.; Berndt, N.; Pietzsch, J.; MáThé, D.; Bachmann, M.; Beck-Sickinger, A. G.

Imaging of Ghrelin receptors in vivo provides unique potential to gain deeper understanding on Ghrelin and its receptors in health and disease, in particular, in cancer. Ghrelin, an octanoylated 28-mer peptide hormone activates the constitutively active growth hormone secretagogue receptor type 1a (GHS-R1a) with nanomolar activity. We developed novel compounds, derived from the potent inverse agonist K-(D-1-Nal)-FwLL-NH2 but structurally varied by lysine conjugation with 1,4,7-triazacyclononane,1-glutaric acid-4,7-acetic acid (NODAGA), palmitic acid and/or diethylene glycol (PEG2) to allow radiolabeling and improve pharmacokinetics, respectively. All compounds were tested for receptor binding, potency and efficacy in vitro, for biodistribution and -kinetics in rats and in preclinical prostate cancer models on mice. Radiolabeling with Cu-64 and Ga-68 was successfully achieved. The Cu-64- or Ga-68-NODAGA-NH-K-K-(D-1-NaI)-F-w-L-L-NH2 radiotracer were specifically accumulated by the GHS-R1a in xenotransplanted human prostate tumor models (PC-3, DU-145) in mice. The tumors were clearly delineated by PET. The radiotracer uptake was also partially blocked by K-(D-1-Nal)-FwLL-NH2 in stomach and thyroid. The presence of the GHS-R1a was also confirmed by immunohistology. In the arterial rat blood plasma, only the original compounds were found. The Cu-64- or Ga-68-NODAGA-NH-K-K-(D-1-NaI)-F-w-L-L-NH2 radiolabeled inverse agonists turned out to be potent and safe. Due to their easy synthesis, high affinity, medium potency, metabolic stability, and the suitable pharmacokinetic profiles, they are excellent tools for imaging and quantitation of GHS-R1a expression in normal and cancer tissues by PET. These compounds can be used as novel biomarkers of the Ghrelin system in precision medicine.

Keywords: Cancer; Prostate cancer; growth hormone secretagogue receptor (GHS-R); small animal imaging; Copper-64; Gallium-68

Publ.-Id: 32241

Non-radiative energy transfer and selective charge transfer in a WS2/(PEA)2PbI4 heterostructure

Karpińska, M.; Liang, M.; Kempt, R.; Finzel, K.; Kamminga, M.; Zhang, N.; Knodlseder, C.; Maude, D. K.; Baranowski, M.; Łopotowski, Ł.; Ye, J.; Kuc, A. B.; Plochocka, P.

Van der Waals heterostructures are currently the focus of intense investigation, this is essentially due to the unprecedented flexibility offered by the total relaxation of lattice matching requirements, and their new and exotic properties compared to the individual layers. Here, we investigate the hybrid transition metal dichalcogenide/2D perovskite heterostructure WS2 /(PEA)2 PbI4 . We present the first DFT calculations of a heterostructure ensemble, which reveal a novel band alignment, where direct electron transfer is blocked by the organic spacer of the 2D perovskite. In contrast, the valence band forms a cascade from WS2 through the PEA to the PbI4 layer allowing hole transfer. These predictions are supported by optical spectroscopy studies, which provide compelling evidence for both charge transfer, and non-radiative transfer of the excitation (energy transfer) between the layers. Our results show that TMD/2D perovskite heterostructures provide a flexible and convenient way to engineer the band alignment.

  • ACS Applied Materials and Interfaces 13(2021)28, 33677-33684
    Online First (2021) DOI: 10.1021/acsami.1c08377


  • Secondary publication expected from 06.07.2022

Publ.-Id: 32240

Data for: Experimental investigation of the return flow instability in magnetic spherical Couette flow

Ogbonna, J. E.; Garcia Gonzalez, F.; Gundrum, T.; Seilmayer, M.; Stefani, F.

Experimental data, numerical data, and programming scripts

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-09-16
    DOI: 10.14278/rodare.789
    License: CC-BY-4.0


Publ.-Id: 32239

Guided capped particles propulsion via hydrogen peroxide decomposition under magnetic field

Alsaadawi, Yara; Heigl, M.; Eichler-Volf, A.; Albrecht, M.; Erbe, A.

Janus particles are one type of artificial microswimmers consisting of two asymmetrically functionalized surfaces. With proper manipulation, one can control their displacement from one point to another at a certain rate, clustering, and orientation. In this work, we employed capped Janus particles. The caps consisted of several alternating thin layers of Co and Pd, and sealed with a 2.1-nm Pd layer, giving a total cap thickness of 17 nm. The Co/Pd combination provides both, magnetic and H2O2 – catalytic properties for the cap, respectively. These unique properties lead to particle propulsion upon applying an external stimulus. To employ both mechanisms, we investigated propulsion under different combinations of H2O2 concentrations and magnetic fields. Since the magnetic element in the cap plays a critical role in cap orientation and mutual interaction, thereby promoting particle clustering1, we studied one particle system as well as two- and three-particle systems. Furthermore, as the swimming behavior is highly affected by the boundary conditions of its surrounding environment2, varying surface properties were incorporated during the experiments.

  • Poster (Online presentation)
    Microswimmers – From Single Particle Motion to Collective Behaviour, 26.-29.10.2020, Bonn, Germany

Publ.-Id: 32238

Ultra-High Negative Infrared Photoconductance in Highly As-doped Germanium Nanowires Induced by Hot Electron Trapping

John, J.; Dhyani, V.; Georgiev, Y.; Gangnaik, A.; Biswas, S.; Holmes, J.; Das, A.; Ray, S.; Das, S.

Here, we report the observation of negative photoconductance (NPC) effect in highly arsenic-doped germanium nanowires (Ge NWs) for the infrared light. NPC was studied by light-assisted Kelvin probe force microscopy, which shows the depletion of carriers in n-Ge NWs in the presence of infrared light. The trapping of photocarriers leads to high recombination of carriers in the presence of light, which is dominant in the n-type devices. Furthermore, a carrier trapping model was used to investigate the trapping and detrapping phenomena and it was observed that the NPC in n-Ge occurred, because of the fast trapping of mobile charge carriers by interfacial states. The performance of n-type devices was compared with p-type NW detectors, which shows the conventional positive photoconductive behavior with high gain of 104. The observed results can be used to study the application of Ge NWs for various optoelectronic applications involving light tunable memory device applications.

Keywords: negative photoconductivity; infrared detection; hot electron trapping; germanium nanowire; diameter-dependent photoconductance

Publ.-Id: 32237

Towards Scalable Reconfigurable Field Effect Transistor using Flash Lamp Annealing

Khan, M. B.; Ghosh, S.; Prucnal, S.; Mauersberger, T.; Hübner, R.; Simon, M.; Mikolajick, T.; Erbe, A.; Georgiev, Y.

Introduction: For decades the miniaturization of logic circuitry was a result of down scaling of the field effect transistor (FET). This scaling has reached its end and, therefore, new device materials and concepts have been under research for the last years. One approach is to increase the functionality of an individual device rather than scaling down its size. Such a device concept is the reconfigurable FET (RFET), which can be configured to n- or p-polarity dynamically [1].
RFETs are based on Schottky barrier FETs and feature an intrinsic Si nanowire (NW) channel. The Schottky junctions are formed by placing Nickel (Ni) contacts on both ends of the NW and conductive Ni-silicide segments are formed in the NW by an annealing process. In RFETs, two gates are usually placed on top of these Schottky junctions and by the application of electrostatic potential at the gates unipolar n- or p-transport is tuned in the channel. There are several Ni-silicide phases out of which NiSi2 is preferred as it yields sharp NiSi2-Si junctions. Moreover, its metal work function is near the mid bandgap of Si. This enables tuning the RFET to n- or p-transport by respectively bending the bands when applying electrostatic potential at the gates (Fig. 1).
Top-down fabrication of Schottky barrier FETs is a pre-requisite for the large-scale integration of RFETs. The challenges in this fabrication process include proper patterning of NWs, obtaining symmetric p- and n-currents and the scalability of the devices. The first two tasks have been solved as reported in [2]. However, the lack of controllable intrusion of silicide into the NWs remains an obstacle for device scalability [3-5]. Here we report that a silicidation process based on millisecond flash lamp annealing (FLA) significantly improves the uniformity of silicide intrusion at the two ends of the NWs. Such a gain in silicidation control will decisively allow creating RFETs with short channel lengths.
Fabrication: The devices are fabricated on silicon-on-insulator (SOI) substrates with 20 nm undoped top Si layer and 102 nm buried oxide. Electron beam lithography (EBL) and dry etching are used to fabricate NWs with 20 nm width as described in [3]. NWs are oxidized with a rapid thermal process and a ~6 nm thick SiO2 shell is formed to passivate NW surface. After wet etching SiO2 from desired areas, Ni contacts are placed in those areas using EBL and Ni evaporation. FLA is used for silicidation of the NWs and the results show equally long silicide intrusions (Fig. 2).
Results: The FLA process time is much shorter (0.5-20 ms) compared to conventional rapid thermal annealing (RTA) [6]. FLA based silicidation process is developed which, unlike previously reported RTA based processes, can deliver scalable RFETs. High resolution TEM (HRTEM) shows the formation of the desired NiSi2 phase and atomically abrupt Schottky junctions (Fig. 4). This is also confirmed by element mapping based on energy dispersive X-ray spectroscopy (EDXS) (Fig. 3). The transfer characteristics of the device with back-gate operation show an ambipolar behavior with an ON/OFF ratio of 9 orders of magnitude (Fig. 5). The gate voltage (VBG) was swept from -30 V to 30 V and the drain to source voltage (VD) was varied from 0.25 V to 0.75 V. The unipolar behavior can be tuned by fabricating two or more top gates. This will also reduce the additional hysteresis caused by using the buried oxide as a very thick gate dielectric.
Applications: The FLA-based silicidation process enables channel scaling. Devices based on this process show promising results and have potential applications as devices with reduced power consumption and low chip area [7]. These RFETs can also be used for the fabrication of power-efficient multi-independent gate-based logic circuits [8]. Moreover, the number of transistors and the chip area consumption can be reduced with the help of these transistors, preserving at the same time the functionality of the integrated circuits [9].
1.Heinzig, A. et al., Nano Lett., 2011.12(1):pp.119-124. 2.Simon, M. et al.,IEEE Trans Nanotechnol, 2017.16(5):pp.812-819.
3.Khan, B.M. et al., Appl. Sci. 2019. 9(17),3462. 4.Habicht, S. et al., Nanotechnology, 2010. 21(10): pp.105701.
5.Ogata, K. et al., Nanotechnology,2011.22(36):pp.365305. 6.Rebohle, L. et al., Semicond Sci Technol, 2016. 31(10): pp.103001.
7.Gaillardon, P.E. at al., in LATS, 2016, pp.195-200. 8.Rai, S. et al., IEEE Transactions VLSI, 2019.27(3):pp.560-572.
9.Raitza, M., et al., in DATE.2017,pp.338-343.

  • Contribution to proceedings
    2020 Device Research Conference (DRC), 21.-24.06.2020, Columbus, OH, USA

Publ.-Id: 32236

Defect engineering in two-dimensional materials: from fundamentals to applications

Ghorbani Asl, M.

It is well known that defects have a remarkable influence on the properties of 2D materials, including optical, electrical, thermal, and mechanical properties. Irradiation with electron and ion beams allows precise control of defect generation by altering beam conditions and exposure dose. Although the response of bulk targets to ion irradiation has been extensively investigated, much less is known about the effects of ion bombardment on 2D materials.
We have studied the effects of ion irradiation on 2D materials by using analytical potential molecular dynamics combined with Monte Carlo simulations. In particular, we focused on the defect production mechanisms and characterized different types of defects in transition-metal dichalcogenides. The amount of damage in MoS2 by the impacts of noble gas clusters was explored for a wide range of energies and incident angles. It was found that the behavior of free-standing and supported 2D materials under the ion beam can be quite different, as the backscattered ions or atoms sputtered from the substrate can completely govern defect production. We showed that cluster irradiation can be used to produce uniform pores in 2D MoS2 with the diameter being dependent on cluster size and energy.6 Ion beam irradiations can also be used to displace sulfur atoms preferentially from either top or bottom layers of S atoms in MoS2 and also clean the surface from adsorbents. The possibility of changing defect concentrations or inducing local amorphization of a 2D material opens a path for tuning its physical properties via a combination of thermal treatment and a reactive vapor. These findings help to understand the fundamental physical mechanisms underlying ion irradiation of low-dimensional materials, which opens many opportunities for the beam-mediated engineering of the devices and nanomeshes for, e.g., DNA sequencing or molecule separation.

Keywords: two-dimensional materials; defects; ion irradiation; molecular dynamics simulations

  • Invited lecture (Conferences) (Online presentation)
    IV Internatiol Symposium Modern Materials Science, 17.11.2020, Moscow, Russia

Publ.-Id: 32235

Resonant Tunneling and Hole Transport Behavior in Low Noise Silicon Tri-gate Junctionless Single Hole Transistor

Uddin, W.; Maity, S.; Dhyani, V.; Ahmad, G.; Georgiev, Y.; Das, S.

The fabrication of p-type silicon junctionless tri-gate transistors and their temperature dependent transport studies are reported in this work. The fabricated transistors have shown a good transfer characteristic down to a low temperature of ~ 80 K with an ON/OFF ratio of 106. The threshold voltage and the subthreshold slope were found to be dependent on temperature. In particular, the threshold voltage and the flat band voltage have positive slopes of 2.24 and 1.19 mV K−1, respectively, with temperature. Channel resistance was found to be increasing with decreasing temperature. The devices have shown a typical 1/f noise behavior in the frequency range of (1–50) Hz and 1/f2 type behavior in the frequency range of (50–100 Hz). At a temperature of 4.2 K, current vs. gate voltage characteristic at a fixed source drain bias shows clear coulomb peaks with different intervals for different gate bias voltages and the observed spikes were consistent within the sub-bands. We relate this to the single hole tunneling, mediated by the charged acceptors available in the channel region. Coupling strength of the dopants was also studied.

Keywords: Junctionless Nanowire Transistor; Temperature dependent Transport; Quantum transport; Coulomb diamonds

Publ.-Id: 32234

Negative resistance for colloids driven over two barriers in a microchannel

Erbe, A.; Leiderer, P.; Kreuter, C.

Video of superparamagnetic colloidal particles which are confined in a microchannel of 30µm width. The particles are driven into motion by tilting the microscope. Two barriers define an island in the channel, which causes an ordered region in the center of the channel. Transport through this island is observed as function of time and tilt angle.

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-01-31
    DOI: 10.14278/rodare.792
    License: CC-BY-4.0


Publ.-Id: 32233

A Focused Ion Beam based in-situ cryo high resolution instrument for multimodal analysis in nano-biology

Hlawacek, G.; Barrahma, R.; Bouton, O.; Biesemeier, A.; Serralta Hurtado De Menezes, E.; Klingner, N.; de Castro, O.; Gnauck, P.; Lucas, F.; Duarte Pinto, S.; Wirtz, T.

Studying the interaction of nano-particles with biological tissue at the nanometer scale in a form as close as possible to the native wet environment is a key challenge in many nano-toxicological questions. The nanomaterial risk identification involves their physico-chemical characterization currently employing a variety of techniques and separate instruments. This makes the characterization an expensive and time-consuming process.
Here, we are developing a new integrated instrument for the ion beam based characterization of nanoparticles. The aim is to improve the efficiency of the nanomaterial characterization workflow by integrating several ion beam based techniques in one single instrument. The npSCOPE instrument is based on the well known Helium Ion Microscope technology [1] allowing the sample to be irradiated with very finely focused He + and Ne + ion beams at the nanometer-scale. Furthermore, the instrument incorporates detectors for secondary electron imaging, a secondary ion mass spectrometer (SIMS) for chemical analysis [2] and a detector allowing the detection of transmitted ions/atoms to obtain in-situ structural/3D visualisation data (STIM) [3]. The instrument will allow the characterization of nanoparticles in their native state as well as embedded in complex matrices (e.g. biological tissue, liquid, etc.). A further key feature of the instrument is cryo-capability, including a 5 axis cryo-stage, in order to perform analyses of biological samples in a frozen-hydrated state and thus avoid artefacts caused by classical sample preparation (e.g. chemical fixation) used for HV or UHV imaging of biological specimens at room temperature.
Here, we will present the instrument, report on the instrument’s performance and discuss the correlative microscopy capabilities. We will present first results obtained with the npSCOPE instrument on different kinds of nano-particle samples relevant in the field of nano-toxicology.
(For further information please visit
[1] G. Hlawacek, A. Golzhä user (eds.), Helium Ion Microscopy (2016) Springer.
[2] T. Wirtz, O. De Castro, J.-N. Audinot, P. Philipp, Ann. Rev. Anal. Chem. 12 (2019).
[3] E. Serralta, Nico Klingner, Olivier De Castro, Michael Mousley, Santhana Eswara, Serge Duarte Pinto, Tom Wirtz, Gregor Hlawacek; Scanning transmission imaging in the helium ion microscope using a microchannel plate with a delay line detector, submitted to Beilstein Journal of Nanotechnology (2020).
This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No. 720964.

Keywords: HIM; STIM; npSCOPE

  • Invited lecture (Conferences) (Online presentation)
    IAEA Technical Meeting on Imaging Using Ionizing Radiation to Address Biological Challenges, 30.11.-03.12.2020, Vienna, Österreich

Publ.-Id: 32232

Helium ion microscopy and its application to low fluence materials modification

Hlawacek, G.

Helium Ion Microscopy has become a standard imaging and nanofabrication technique in last decade. In my presentation I will introduce the technqiue and the underlying reasons for its exceptional capabilities. The latter include high lateral resolution, high depth of focus, ability to image insulating samples and exceptional nanofabrication capabilites. In the second part I will highlight selected applications of the method. This will include modification of 2D materials, magnetic materials and applications related to quantum technology. I will also allude on past and current developments in ion beam based analysis using the HIM.
[1] Hlawacek, G. & Gölzhäuser, A. (Eds.) Helium Ion Microscopy, Springer International Publishing, 2016.
[2] Hlawacek, G.; Veligura, V.; van Gastel, R. & Poelsema, B. Helium ion microscopy, J. Vac. Sci. Technol. B, 2014, 32, 020801

Keywords: HIM

  • Lecture (Conference) (Online presentation)

Publ.-Id: 32231

Helium Ion Microscope based nanofabrication

Hlawacek, G.

Helium Ion Microscope based nanofabrication

Keywords: HIM; nanofabrication; GFIS

  • Lecture (others) (Online presentation)
    Nanofabrication webinar series @ Master on Advanced Nanoscience and Nanotechnology, 23.04.2020, Barcelona, Spain
  • Lecture (others) (Online presentation)
    Webinar series on Advances Nanofabrication, 26.02.-9.4.2021, Barcelona, Spanien

Publ.-Id: 32230

Introduction to alpaka

Stephan, J.

This talk covers the alpaka parallel programming library as well as the surrounding ecosystem. It features an introduction to the alpaka programming model, a presentation of the ecosystem libraries cupla, Vikunja, LLAMA and bactria, and a glimpse into the future.

Keywords: alpaka; LLAMA; Vikunja; RedGrapes; cupla; C++; bactria; parallel programming; HPC; GPGPU

  • Open Access Logo Lecture (others) (Online presentation)
    HEP-CCE PPS weekly meeting, 29.01.2021, Batavia, Illinois, United States of America
  • Open Access Logo Lecture (others) (Online presentation)
    Compute Accelerator Forum, 12.05.2021, Genf, Schweiz


Publ.-Id: 32229

Open-source PEM fuel cell model combining the unsaturated flow theory for porous media with Springer's model

Weber, N.; Knüpfer, L.; Zhang, S.; Reimer, U.; Beale, S.; M. Chaparro, A.; Ferreira-Aparicio, P.

The presentation gives an overview on a PEM fuel cell model developed within the framework of OpenFOAM. The capabilities of the model are demonstrated by simulating a conventional PEM fuel cell, which has been developed by CIEMAT. This cell is supplied by pure oxygen and hydrogen with a humidification of 100%, while operating at 80°C. The measured polarisation curve is reproduced by the OpenFOAM model quite well. Moreover, it allows to illustrate the current distribution, liquid water formation and the depletion of reactants within the porous electrodes. The model can easily be applied to other fuel cell geometries, thus helping in their design or operation.

  • Lecture (Conference)
    16th OpenFOAM Workshop 2021, 08.06.2021, Dublin, Irland

Publ.-Id: 32227

Igneous-metamorphic basement of Taquetr´en Range, patagonia, Argentina: A key locality for the reconstruction of the paleozoic evolution of patagonia

Renda, E. M.; González, P. D.; Vizán, H.; Oriolo, S.; Prezzi, C.; Ruiz González, V.; Schulz, B.; Krause, J.; Basei, M.

In this contribution, we present the stratigraphy of the igneous and metamorphic rocks of the Taquetr´en Range, a sector located in the southernmost margin of the North Patagonian Massif (42◦42′ 00′′ S - 69◦30′00′′ W). Its igneous and metamorphic basement is composed of the newly defined “Lagunita Salada Igneous-Metamorphic Complex” (LSIMC), “Paso del Sapo Plutonic Complex” (PSPC) and “Sierra de Taquetr´en Plutonic Complex” (STPC). The LSIMC comprises gneisses, schists, amphibolites and migmatites, which share a S1–S2 penetrative foliation with a mean orientation of 300◦–330◦/40◦–60◦ NE. Based on mineral paragenesis, metamorphic conditions of these rocks are the result of Barrovian-type metamorphism in the upper amphibolite to granulite facies. EPMA Th–U–Pb ages of monazites display two isochron main populations at 379 ± 5 Ma and 323 ± 5 Ma, which suggest long-term high-temperature conditions for the region between Late Devonian and Carboniferous times. The Complex is intruded by concordant tonalites, granodiorites, porphyric granites and minor pegmatites and felsic dykes, which are grouped in the PSPC. Both the LSIMC and PSPC are intruded by unfoliated peraluminous granitoids grouped in the STPC. Based on field and microstructural data, the pervasive foliation identified in the PSPC was caused by processes ranging from magmatic flow to solid-state deformation, indicating a syntectonic emplacement. Zircon U–Pb analysis by LA-ICP-MS in the PSPC shows two distinguishable groups with concordia ages of 314.1 ± 2.2 Ma and 302.8 ± 2.2 Ma, interpreted as the crystallization and subsequent deformation age respectively, related to protracted high-strain conditions. The outcrops in this area represent an almost full tectonic cycle encompassing from medium-high grade metamorphic rocks and syn-tectonic intrusions to posttectonic intrusions, therefore configuring a key locality for the analysis of North Patagonian Paleozoic evolution. Moreover, based on the compilation of U–Pb zircon ages, a ~20 My magmatic gap period (360-340 Ma) is recognized in the southwestern margin of the North Patagonian Massif coeval with amphibolite-granulite facies metamorphism in different sectors of the Central Patagonian Igneous-Metamorphic Belt, presenting thus important implications for the tectonic evolution of the area.

Keywords: Patagonia; Paleozoic; Igneous-metamorphic basement; U–Pb zircon; Th–U–Pb monazite

Publ.-Id: 32226

Develop common input and output standards for PIC-codes

Debus, A.; Bertini, D.; Quere, F.; Vincenti, H.; Horny, V.; Vieira, J.

JRA PRISES, Task 2.5: Development of common input/output standards of Particle-In-Cell (PIC) codes and associated in-situ and post-processing tools, Status report

  • Lecture (others) (Online presentation)
    LASERLAB 5 - JRA progress meetings, 18.11.2020, Dresden, Deutschland

Publ.-Id: 32224

Feldspar recycling across magma mush bodies during the voluminous Half Dome and Cathedral Peak stages of the Tuolumne intrusive complex, Yosemite National Park, California, USA

Oppenheim, L. F.; Memeti, V.; Barnes, C. G.; Chambers, M.; Krause, J.; Esposito, R.

Incremental pluton growth can produce sheeted complexes with no magma-magma interaction or large, dynamic magma bodies communicating via crystal and melt exchanges, depending on pulse size and frequency of intrusions. Determining the degree and spatial extent of crystal-melt exchange along and away from plutonic contacts at or near the emplacement level, such as in the large, long-lived Tuolumne intrusive complex (TIC) in California, sheds light onto the process and evolution of incremental growth.
This study used field mapping and petrographic and geochemical analysis of plagioclase and K-feldspar populations in the equigranular Half Dome (eHD), porphyritic Half Dome (pHD), and Cathedral Peak (CP) Granodiorites of the southeastern section of the TIC to determine the presence and/or extent of feldspar recycling at interunit contacts. Our results suggest that contacts between major units are predominantly ~400-m- to 3-km-thick gradational zones. K-feldspar is compositionally distinct in eHD and neighboring gradational zones and shows no evidence of mixing. K-feldspar in a gradational zone between pHD and CP shows evidence of mixing between the two. Plagioclase in eHD and CP display distinct ranges of anorthite content, Sr, and light rare earth element abundances; both populations are observed in pHD. Major oxide and trace element calculations of melts in equilibrium with plagioclase cores indicate that the melts were more silicic, less calcic, and lower in Sr and Rb than corresponding analyzed whole-rock samples. These results suggest that the magmas also underwent plagioclase and biotite accumulation. The presence of two plagioclase populations in pHD is consistent with eHD and CP hybridizing to form pHD in an increasingly maturing and exchanging TIC magmatic system during the eHD-pHD-CP stages but before groundmass and small K-feldspar phenocrysts crystallized.

Publ.-Id: 32221

Erzlabor - we visualize value!

Bachmann, K.

Dieser Beitrag stellt Erzlabor, ein Spin-Off des HZDR, den Partnern des EIT RawMaterials in Europa vor.

  • Invited lecture (Conferences) (Online presentation)
    EIT Brokerage Event, 26.11.2020, Freiberg, Deutschland

Publ.-Id: 32220

Geometallurgical Characterization of Tailing Storage Facilities

Bachmann, K.

This presentations shows novel analytical methods and geometallurgical modelling techniques for re-mining of tailing storage facilities.

  • Invited lecture (Conferences) (Online presentation)
    Online-Workshop: Re-mining de residuos, 15.12.2020, Freiberg, Deutschland

Publ.-Id: 32217

Vom Erz zum Metall – Innovative Materialcharakterisierung durch Automatisierte Mineralogie

Bachmann, K.

‚Automatisierte Mineralogie‘ bezeichnet eine analytische Untersuchungsmethode auf Basis einer Kombination von Rasterelektronenmikroskopie (REM) und energiedispersiver Röntgenspektroskopie (EDS). Automatisierte mineralogische Untersuchungen bieten die einzigartige Möglichkeit quantitative Daten einer Vielzahl von Parametern aufzustellen, die für die Entwicklung und kritische Bewertung von Aufbereitungstests greifbar sind. Diese Parameter umfassen den modalen Mineralbestand, den kalkulierten Elementgehalt, Elementverteilungen, Mineralassoziationen, Größenverteilungen von Partikeln und Mineralkörnern, Partikeldichteverteilungen sowie die Mineralfreisetzung. Aus den Analysedaten können auch Proben-Übersichtsbilder (‚Mineralkarten‘) und Bilder bestimmter Mineralgruppen extrahiert werden.
Die Möglichkeiten werden anhand von zwei Beispielen verdeutlicht. Zum Einen wurde sogenannte Schwarzmasse charakterisiert, ein sekundärer Rohstoff, welche beim Recycling von Li-Ionenbatterien entsteht. Zum Anderen, geht es um primäre Lagerstätten, hier die Gewinnung von Platingruppenelementen in einer Chromitlagerstätte in Südafrika.

  • Invited lecture (Conferences) (Online presentation)
    FA-Lagerstätten GDMB, 14.05.2020, Freiberg, Detschland

Publ.-Id: 32216

Charakterisierung von Lithium-Ionen-Batterien (LIB) in Recyclingprozessen und Abschätzung der Aufschlusseffizienz von Elektroden mithilfe automatisierter Mineralogie

Bachmann, K.; Vanderbruggen, A.; Hayagan, N. L.; Rudolph, M.

Lithium-Ionen-Batterien (LIBs) gehören zu den derzeit wichtigsten elektrochemischen Energiespeichersystemen für elektronische Mobilgeräte und Elektrofahrzeuge. Die wachsende weltweite Nachfrage nach LIBs, geht mit einer Erhöhung des Bedarfs an Co, Mn, Ni, Li und Graphit einher. Diese Erhöhung der Nachfrage dieser Rohstoffe stellt eine besondere Herausforderung für den schon jetzt angespannten weltweiten Rohstoffmarkt dar, verbunden mit Versorgungsrisiken, Preisschwankungen und Marktmonopolen. Tatsächlich sind Co und natürlicher Graphit in Europa seit 2010 als kritische Rohstoffe (CRM) geführt, Li sowie Mn befinden sich an der Grenze der Kritikalität. Um potenziell die Kluft zwischen Angebot und Nachfrage zu verringern sowie die europäischen Nachhaltigkeitsziele zu erreichen, hat das Recycling von Lithium-Ionen-Batterien (LIB) hat in den letzten Jahren viel Aufmerksamkeit auf sich gezogen. Hierbei wird sich hauptsächlich auf die wertvollen Metalle wie Kobalt, Nickel und Lithium konzentriert. Allerdings gehen während des Recyclingprozesses erhebliche Mengen anderer Komponenten wie Elektrolyt, Separator oder Graphit verloren. So kann Graphit zum Beispiel während der pyrometallurgischen Behandlung entweder abgeschlackt oder als Reduktionsmittel verbraucht werden. Darüber hinaus gehen einige andere wertvolle Metalle wie Co in den Grobfraktionen durch einen zu geringen Aufschlussgrad an die Berge verloren. Aus diesem Grund müssen neue und umfassende LIB-Recyclingverfahren gefunden werden.
In dieser Studie werden zur Freisetzung von aktiven Materialien aus Elektroden sowohl eine mechanische als auch thermo-mechanische Recyclingprozessroute angewendet. Dabei wird neben den werthaltigen Metallen insbesondere die Rückgewinnung von Graphit in den Fokus gestellt. Die mechanische Route arbeitet mit einem Schlagscherbrecher, während für die thermo-mechanischen Versuche die Batterien vor dem Zerkleinern bei 500-650 °C vakuumpyrolysiert wurden. Die sogenannte Schwarzmasse-Fraktion kleiner als 1 mm wurde abgetrennt und basierend auf der Partikelgrößenverteilung in 4 Größenfraktionen klassifiziert. Eine genaue Charakterisierung sowohl der Hauptchemie als auch eine detaillierte Charakterisierung der enthaltenen Phasen im recycelten Materials stellt nach wie vor eine große Herausforderung dar. Deshalb wurde jede Fraktion wurde durch verschiedene analytische Methoden charakterisiert, einschließlich Röntgenfluoreszenz (XRF), Röntgenbeugung (XRD), Atomabsorptionsspektrometrie (AAS). Für eine gute Visualisierung und Quantifizierung der Ergebnisse des Aufbereitungserfolgs und Prozesseffizienz ist eine detailliertere analytische Charakterisierung erforderlich. Diese Studie schlägt eine innovative und neuartige neue Charakterisierungsmethode vor, die auf automatisierter Mineralogie basiert. Dabei werden verschiedene wichtige Partikelparameter wie Größe, Zusammensetzung und Verwachsung analysiert und quantitativ ausgewertet. Das für die Messungen genutzte Mineral Liberation Analyzer (MLA) System nutzt eine Kombination aus Rasterelektronenmikroskopie (REM) -Bildanalyse und energie-dispersiver Röntgenspektroskopie (EDS) und ist im primären Rohstoffsektor als leistungsstarke Methode etabliert. Allerdings fehlen für den Einsatz im sekundären Rohstoffsektor dezidierte Datenbanken, um die Partikel der Schwarzmasse schnell und präzise analysieren zu können. Eine analytische Herausforderung dieser Studie ist es demnach auch eine Datenbank zur Batteriecharakterisierung zu erstellen und für breite Anwendungsbereiche einsetzen zu können.
Im Ergebnis zeigt die hier vorgestellte Studie, dass bei den angewendeten Zerkleinerungsverfahren eine Freisetzungsselektivität der Elektrodenfolien beobachtet werden konnte. Der thermo-mechanische Prozess setzt dabei mehr aktive Partikel aus den Folien frei als ein mechanischer Prozess allein. Infolgedessen sind insbesondere bei thermo-mechanisch zerkleinerten Proben die meisten Graphitpartikel in der <63 um-Fraktion konzentriert. Cu-Folien werden generell besser aufgeschlossen als Al-Folien. Es wurde jedoch festgestellt, dass der Prozesstyp unterschiedliche Auswirkungen auf die Freisetzung von Al-Folie hat. Der thermomechanische Prozess setzt mehr Metalloxide aus der Al-Folie frei als nur der mechanische Prozess. Der Al-Bruch wird jedoch stärker durch die Wärmebehandlung beeinflusst, wodurch feinere Al-Partikel entstehen, die für weitere hydrometallurgische Wege problematisch sein können.

  • Poster (Online presentation)
    Aufbereitung und Recycling, 12.-13.11.2020, Freiberg, Deutschland

Publ.-Id: 32215

Prädiktive Geometallurgie in Freiberg – von „Virtual Twins“ und Prozessoptimierung

Bachmann, K.; Pereira, L.; Tolosana Delgado, R.; van den Boogaart, K. G.; Gutzmer, J.

Der moderne Bergbausektor steht vor gewaltigen technischen Herausforderungen. Dazu zählen der Rückgang von Erzgehalten, der zunehmende Umgang mit komplexen Mineralparagenesen und sehr feinen Korngrößen aber auch einer steigenden Erzvariabilität. Mit Hilfe geometallurgischer Modelle versucht die Bergbauindustrie diese Herausforderungen zu bewältigen und das Verhalten des Erzes während des Abbaus, der Aufbereitung und der Verhüttung quantitativ vorherzusagen. Um hier einen Beitrag zu leisten, wird am Standort Freiberg seit 2008 geometallurgische Kernkompetenz aufgebaut. Diese Entwicklung wurde mit der Gründung des Helmholtz-Instituts Freiberg für Ressourcentechnologie (HIF), einer gemeinsamen Gründung des Helmholtz-Zentrums Dresden-Rossendorf (HZDR) und der TU Bergakademie Freiberg (TU Bergakademie Freiberg) im Jahr 2011, stark beschleunigt. Aus diesem Grund zählt Freiberg heute weltweit zu den wichtigsten Forschungs- und Entwicklungsstandorten der Geometallurgie. In diesem Artikel werfen wir einen Blick auf den aktuellen Stand der Entwicklungen, mit Fokus auf zwei sehr erfolgreiche Projekte im Bereich der geometallurgischen Modellierung, sowohl primärer als auch sekundärer Rohstoffe.

  • Open Access Logo ACAMONTA 27(2020), 22-26


Publ.-Id: 32212

Experimental observation of elevated heating in dynamically compressed CHfoam

Falk, K.; Fontes, C. J.; Fryer, C. L.; Greeff, C. W.; Holec, M.; Johns, H. M.; Montgomery, D. S.; Schmidt, D. W.; Smid, M.

We present an experimental result of significantly increased heating in a laser-driven blastwaveexperiment carried out at the OMEGA laser facility. Abnormally high temperatures wereobserved in warm dense CH compared to older experiments and theoretical predictions. Thehigher temperatures in compressed CH were linked to an improved smoothness of the laserintensity profile, which resulted in better efficiency of the drive and coupling of more energyinto the system compared to previous similar experiments. Fifteen beams with combinedintensity of∼7×1014W cm−2and a square intensity profile with 2 ns duration were used todrive a strong shock, which subsequently developed to a blastwave travelling through lowdensity CH foam creating warm dense matter. Multiple diagnostics were used to examine thethermodynamic conditions in the warm dense CH foam. Velocity interferometry (VISAR) andstreaked pyrometry (SOP) observed increased blastwave velocities, while x-ray Thomsonscattering (XRTS) measured elevated temperatures of 17.5−35 eV in compressed CH foam.The experimental results were compared to hydrodynamic simulations and a potentialcontribution from x-rays to the elevated temperatures in the dense material was considered.

Publ.-Id: 32211

Dataset for: Flow morphologies in straight and bent horizontal pipes

Döß, A.; Schubert, M.; Wiedemann, P.; Schleicher, E.; Hampel, U.

This data set contains gas phase fraction data (void files, v.) obtained from wire-mesh sensor recordings up and downstream of horizontal pipe bends. The test sections and experimental setups are explained in the correpsonding journal paper.

The post processing was done with the Wire-mesh Sensor Framework GUI (Version 1.3.0).

The archive is organzed as follows:
(1) Each .zip file contains the void files for one distinct location (INL, OUT or REF) for the respective test sections (S - straight pipe, B - Horizontal 90° Bend, Upr_SB - Upright S-bend, Hor_SB - Horizontal S-bend)  and pipe diameter (DN50 and DN200).

(2) The 'overview.csv' (separator = semicolon, decimal operator: = comma) links the files in this data set to the corresponding flow rates, FFPI degrees of membership and RGB color values as they are presented in the journal paper. The column 'File Prefix' contains the explicit file indicator for the .v-files, the column 'Direcotry' contains the location of in this data set.

(3) The MatLab script  'openvoid.m' exemplarily shows how to read in the data contained in the .v file.

Keywords: Flow morphologies; Horizontal Two-phase flow; Wire-mesh sensor; TERESA

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-01-29
    DOI: 10.14278/rodare.783
    License: CC-BY-4.0


Publ.-Id: 32210

Convection in Liquid Metal Batteries - Comparing Results from OpenFOAM, Semtex and SFEMaNS

Personnettaz, P.; Klopper, T. S.; Benard, S.; Weber, N.; Weier, T.

Switching the energy supply from today’s dominant fossil sources to mainly variable renewable energies (wind and solar) means a fundamental change. It will entail the transformation from a centralised energy system to distributed generation that needs flexibility options to balance supply and demand across time and space. Transmission grid expansions can only partially account for the resulting variations in supply. Therefore, large-scale stationary storage will gain importance in future energy landscapes.

Among the candidates to meet the growing demand for stationary storage are liquid metal batteries (LMBs). Their active materials as well as the electrolyte are in the liquid state. The cell interior consists of two layers of liquid metals interspaced by a molten salt electrolyte in stable density stratification. 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 total costs should therefore largely be determined by those of the active materials. While mass transport in most modern battery systems is typically dominated by diffusion and migration in micrometer-scale liquid layers and solids, convection - with exception of 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 and has a strong influence on cell performance and operational safety. Electric currents, magnetic fields, and heat and mass transfer are tightly coupled with the cells’ electrochemistry.

The talk will focus on the influence of solutal convection in the positive electrode on the cycling behaviour of a cell. We consider a Li-Bi battery, a cell chemistry for that ample experimental material is available in the literature. While this is true for the electrochemical characteristics, detailed experimental information on the flow in these batteries is largely missing. To compensate at least partially for this deficiency, we employ three different codes and compare their results. In the discharged state, the positive electrode consists of a Li(Bi) alloy. When charging the cell, low density Li is removed from the top of the positive electrode. This increases locally the density of the alloy and Li-depleted fluid starts to sink down in plumes. Rapidly, solutal convection drives a flow in the whole cathode and intensely mixes the remaining alloy. While stabilising thermal gradients can occur, densities of the positive electrode’s metal (Bi in our case) are typically an order of magnitude larger than the negative electrode metal (Li here) ones. In comparison, thermal expansion coefficients are quite small and due to the good thermal conductivity of metals, temperature differences tend to be smoothed out quickly. Thus, compositional (i.e. solutal) gradients should dominate over thermal ones and constitute the primary cause or inhibitor of motion in the positive electrode.

The OpenFOAM solver is based on buoyantBoussinesqPimpleFOAM extended by the concentration convection- diffusion equation and by a variable density depending on temperature as well as composition. Mass transfer through the electrolyte-positive electrode interface is captured by an electrochemically consistent mass flux boundary condition.

Onset of solutal convection from an initially well mixed state is studied in 2D for different charging currents. The results are compared to computations done with the spectral element solver Semtex and with the mixed spectral and finite element code SFEMaNS. Both programs are available under the GNU General Public License. While different onset times are to be expected due to the various numerical approaches, growth rates obtained with all three solver match very well. Development of the plumes that are the immediate consequences of the instability is quite consistent across the codes, as well as the formation of larger vortical structures at later stages.

Computations in 3D allow for a more realistic description of the flow and a better understanding of mixing. Due to the limited computational resources available to us we undertook these investigations with the more specialised and fast code Semtex only. Even with this code, care had to be taken to sufficiently resolve the fine plume structures in the early phases of flow development especially near the cells rim.

Properly capturing flow development and mixing in the positive electrode of a typical liquid metal battery allows for a correct description of the cell’s cycling behaviour.

Keywords: Liquid metal batteries; energy storage; solutal convection

  • Open Access Logo Lecture (Conference) (Online presentation)
    16th OpenFOAM Workshop 2021, 08.-11.06.2021, Dublin, Irland

Publ.-Id: 32209

FineFuture: First results in innovative fine-particle flotation

Dirlich, S.

The H2020 Project FineFuture aims at the improvement of the recovery of (ultra) fine particles from primary and secondary resources. Having reached the halftime of the project first results are available, and demonstrate that the proposed advances in the recovery of critical raw materials can be achieved.

Keywords: fine particles; flotation; froth flotation; bubble-particle collision; CFD modelling; critical raw materials

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    PROMETIA Annual Scientific Seminar, 10.12.2020, Paris, Frankreich

Publ.-Id: 32208

Sanierung und Umbau eines Wohnhauses der 1930er Jahre

Schweiker, K.; Dirlich, S.

Das Wohnhaus Wieckestraße Nr. 10 in Dresden ist fast 100 Jahre alt und eines der letzten original erhaltenen Gebäude in der Doppelhaus-Siedlung in Leubnitz-Neuostra. Es steht nicht unter Denkmalschutz. Anliegen ist es, möglichst viel originale Substanz zu erhalten und das Gebäude nachhaltig, ökologisch und der Substanz angemessen zu sanieren und umzubauen. Dabei ist es eine Herausforderung, bei nahezu gleichbleibender Kubatur des kleinen Hauses sowohl mehr Raum, Licht und Großzügigkeit zu schaffen als auch eine gute Balance zwischen denkmalgerechter Sanierung und energetischer Ertüchtigung herzustellen. Ziel ist es, die Förderstufe des KfW-Effizienzhauses 115 zu erreichen. Die Sanierung hat im Juni 2020 begonnen, Fertigstellung und Einzug sind für Dezember 2020 geplant. Trotz vollberuflicher Einbindung erbringen die Bauleute wertvolle Eigenleistungen. Zur Unterstützung und Förderung eines möglichst reibungslosen Ablaufes, für gut funktionierende Abstimmungen, eine wertschätzende Kommunikation, gegenseitigen Respekt und Vertrauen sind vor Baubeginn durch die Architektin, die auch als Dialogprozess-Begleiterin ausgebildet ist, dialogische Kompetenzen und der Dialog als Methode und Übungsform vorgestellt worden. Die bisherige Resonanz ist sehr positiv.

Keywords: sustainable building; resource efficiency; restoration; historic building; retrofit

  • Book chapter
    Weller, Bernhard; Scheuring, Leonie: Denkmal und Energie 2021 - Energieeffizienz, Nachhaltigkeit und Nutzerkomfort, Wiesbaden: Springer Vieweg, 2021, 978-3-658-32248-9, 129-146

Publ.-Id: 32207

Molecular-level speciation of Eu(III) adsorbed on a migmatized gneiss as determined using µTRLFS

Molodtsov, K.; Demnitz, M.; Schymura, S.; Jankovský, F.; Havlová, V.; Schmidt, M.

The interaction of Eu(III) with thin sections of migmatised gneiss from the Bukov Underground Research Facility (URF), CZ was characterized by microfocus time-resolved laser-induced luminescence spectroscopy (µTRLFS) with a spatial resolution of ~20 µm, well below typical grain sizes of the material. By this approach, sorption processes can be characterized on the molecular level while maintaining the relationship of the speciation with mineralogy and topography. The sample mineralogy was characterized by powder X-ray diffraction and Raman microscopy and the sorption was independently quantified by autoradiography using Eu-152. Representative µTRLFS studies over large areas of multiple mm2 reveal that sorption on the heterogeneous material is not dominated by any of the typical major constituent minerals (quartz, feldspar, and mica). Instead, minor phases such as chlorite and prehnite control the Eu(III) distribution, despite their low contribution to the overall composition of the material, as well as common but less studied phases like Mg-hornblende. Especially prehnite shows high a sorption uptake as well as strong binding of Eu to the mineral surface. Sorption on prehnite and hornblende happens at the expense of feldspar, which showed the highest sorption uptake in a previous spatially-resolved study on granitic rock. Similarly, sorption on quartz is reduced, even though only low quantities of strongly bound Eu(III) were found here previously. Our results illustrate how competition of mineral surfaces for adsorbing cations drives metal distribution in heterogeneous systems.

Keywords: µTRLFS; Luminescence spectroscopy; Microscopy; Crystalline rock; Radionuclide migration; Prehnite; Sorption


  • Secondary publication expected from 20.04.2022

Publ.-Id: 32206

Drop Size Dependence of the Apparent Surface Tension of Aqueous Solutions in Hexane Vapor as Studied by Drop Profile Analysis Tensiometry

Fainerman, V. B.; Kovalchuk, V. I.; Aksenenko, E. V.; Sharipova, A. A.; Liggieri, L.; Javadi, A.; Makievski, A. V.; Nikolenko, M. V.; Aidarova, S. B.; Miller, R.

Surface tension experiments were performed using the drop profile analysis tensiometry method. The hexane was injected into the measuring cell at certain times before the formation of the solution drop. The influence of the capillary diameter and solution drop size on the measured apparent dynamic surface tension was studied. The amount of hexane transferred from the vapor phase to the drop was estimated. For large pure water drops, it was shown that the ageing of the drop in the hexane vapor during a long time resulted in the formation of a liquid hexane phase covering the drop, but the volume of this phase did not exceed 0.5 mm3. On the contrary, for surfactant solution drops the volume of the hexane phase covering the drop was essentially larger. Experiments with solution drops were performed to measure the surface tension within a wide range of surfactant concentration. It was found that the dependencies of dynamic surface tension on the C13DMPO and C14EO8 solutions concentration exhibit maxima at concentrations of about 1–2 μmol/L for C14EO8 and 2–5 μmol/L for C13DMPO at ageing times of 100 to 1000 s; these maxima were shown to exist also at equilibrium. This phenomenon is presumably ascribed to the competitive character of simultaneous adsorption of hexane and surfactant.

Related publications


Publ.-Id: 32205

Rückgewinnung von Vanadium aus alkalischen Laugungslösungen unter der Synthese von Nanopartikeln

Kelly, N.; Sanchez Loredo, M. G.; Dupal, O.; Chekhonin, P.; Ebert, D.; Möckel, R.; O’Toole, N.; Reuter, M.

Europa ist auf den Import zahlreicher ökonomisch bedeutender Metalle angewiesen, wobei diese gleichzeitig in vielen sekundären Ressourcen gebunden sind, deren Potential nicht vollständig genutzt wird. Im Rahmen des CHROMIC-Projektes sollen kritische (Cr, Nb) und wertvolle (V, Mo) Metalle unter der Entwicklung innovativer Prozesse zurückgewonnen werden. Dabei erfolgt die gezielte Kombination einer verbesserten Vorbehandlung, einer selektiven alkalischen Laugung sowie einer hoch selektiven Metallrückgewinnung.
Im Zuge des hydrometallurgischen Verfahrens können verdünnte vanadiumhaltige Lösungen erhalten werden, welche für eine effektive Rückgewinnung des Zielmetalls weiter angereichert und aufgereinigt werden müssen. Der vorliegende Beitrag beinhaltet den Vergleich eines mehrstufigen Fällungs- und Solvent-extraktionsprozesses mit der direkten Fällung von Vanadaten aus den beladenen organischen Phasen. Letztere ermöglicht zugleich die Synthese von Nanopartikeln unterschiedlicher Metallvanadate. Der Einfluss der experimentellen Parameter (z.B. Art des Kations, Konzentration von Fällungs- und Extraktionsmitteln sowie des Zielmetalls) wird näher diskutiert, wobei die isolierten Produkte mittels XRD, XRF sowie REM-EDX strukturell charakterisiert werden.

  • Lecture (Conference)
    Jahrestreffen der ProcessNet-Fachgruppen Fluidverfahrenstechnik, Adsorption und Extraktion, 26.-28.02.2020, Berchtesgaden, Deutschland

Publ.-Id: 32203

Interfacial Properties of Tridecyl Dimethyl Phosphine Oxide Adsorbed at the Surface of a Solution Drop in Hexane Saturated Air

B. Fainerman, V.; V. Aksenenko, E.; V. Makievski, A.; Liggieri, L.; Mucic, N.; Javadi, A.; I. Kovalchuk, V.; Miller, R.

The surface tension of C13DMPO aqueous solution drops in hexane vapor is studied using the drop profile method. The hexane was injected into the measuring cell at three different conditions: before the formation of the solution drop, at a certain moment during the adsorption process, and after reaching the equilibrium of surfactant adsorption. The surface tension values for all experiments at the same concentration and different injection situations ultimately coincide with each other after attaining the final equilibration stage. The equilibrium surface tension isotherms of C13DMPO solutions, and the adsorption of both components—surfactant and hexane—were calculated. It was shown that the presence of surfactant leads to an increased hexane adsorption.

Keywords: drop profile analysis tensiometry; surfactant adsorption; solution–alkane vapor interface; dynamic surface tension; thermodynamic model; non-ionic surfactant

Related publications

Publ.-Id: 32202

Salt Effects on Formation and Stability of Colloidal Gas Aphrons Produced by Anionic and Zwitterionic Surfactants in Xanthan Gum Solution

Keshavarzi, B.; Mahmoudvand, M.; Javadi, A.; Bahramian, A.; Miller, R.; Eckert, K.

 This work is devoted to the influence of NaCl salt concentration on the formation and stability of colloidal gas aphrons (CGA) produced by the anionic surfactant sodium dodecyl sulfate (SDS) and zwitterionic surfactant coco amido propyl betaine (CAPB) in the presence of xanthan gum (XG) as a stabilizer. Dynamic surface tension measurements as well as volume and half-life time of the produced foams are considered for stability analysis. A sharp decrease of the half-life time and volume of the CGAs at NaCl concentrations larger than 20,000 ppm was observed, which was attributed to the precipitation of SDS in the solution. The mentioned SDS precipitation altered the dynamic surface tension behavior, dilational surface elasticity, and turbidity of the solution. The main reason for the precipitation of SDS is the increased Krafft point caused by the addition of salt. However, for the zwitterionic surfactant CAPB, the effects of added NaCl on the interfacial properties required for CGAs production was negligible due to the simultaneous effects on the cationic and anionic head groups in the CAPB leading to negligible changes in the net repulsion forces. Yet, an overall reduction in the half-life time of CGAs with increasing salt concentration, even when we have no precipitation, was observed for both surfactants, which could be explained by the reduction in the ability of XG to increase the viscosity with increasing salt concentration.

Keywords: Colloidal gas aphrons; foam formation and stability; drilling fluid; dynamic surface tension; interfacial rheology; cocoamidopropyl betaine; sodium dodecyl sulfate; NaCl

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-02-11
    DOI: 10.14278/rodare.808
    License: CC-BY-4.0


Publ.-Id: 32201

Towards Personalized Radiation Therapy of Liver Metastasis: Importance of Serial Blood Biomarkers

Ajdari, A.; Xie, Y.; Richter, C.; Duda, D. G.; Hong, T. S.; Bortfeld, T.

PURPOSE: To assess the added value of serial blood biomarkers in liver metastasis stereotactic body radiotherapy (SBRT).
MATERIALS AND METHODS: Eighty-nine patients were retrospectively included. Preand mid-treatment blood samples were analyzed for potential biomarkers of the treatment response. Three biomarker classes were studied: gene mutation status; complete blood count (CBC); and inflammatory plasma cytokine (IPC). One-year local failure (LF) and two-year overall survival (OS) were chosen as study endpoints.
Multivariate logistic regression was used for response prediction. Added predictive benefit was assessed by quantifying the difference between the predictive performance of a baseline model (clinicopathological and dosimetric predictors) and the biomarkerenhanced model, using three metrics: (i) likelihood ratio (LR), predictive variance (PV) , and (iii) area under the receiver-operating characteristic curve (AUC).
RESULTS: The most important predictors of LF were mutation in KRAS gene (HR=2.92, 95% CI=[1.17-7.28], p=0.02), and baseline and mid-treatment concentration of plasma interleukin (IL)-6 (HR=1.15 [1.04-1.26], and 1.06 [1.01-1.13], p 0.01).
Absolute lymphocyte count (ALC) and Platelets-to-lymphocyte ratio (PLR) at baseline, as well as neutrophil-to-lymphocyte ratio at baseline and before fraction 3 (HR=1.33 [1.16-1.51] and 1.19 [1.09-1.30]) had the most significant association with OS (p 0.0003). Addition of baseline GEN and IPC biomarkers in predicting LF respectively increased AUC by 0.06 (from 0.73 to 0.79) and 0.07 (from 0.77 to 0.84). In predicting OS, inclusion of mid-treatment CBC biomarkers increased AUC from 0.72 to 0.80, along with significant boosts in LR and PV.


  • Secondary publication expected from 25.03.2022

Publ.-Id: 32200

Salt Effects on Formation and Stability of Colloidal Gas Aphrons Produced by Anionic and Zwitterionic Surfactants in Xanthan Gum Solution

Keshavarzi, B.; Mahmoudvand, M.; Javadi, A.; Bahramian, A.; Miller, R.; Eckert, K.

This work is devoted to the influence of NaCl salt concentration on the formation and stability of colloidal gas aphrons (CGA) produced by the anionic surfactant sodium dodecyl sulfate (SDS) and zwitterionic surfactant coco amido propyl betaine (CAPB) in the presence of xanthan gum (XG) as a stabilizer. Dynamic surface tension measurements as well as volume and half-life time of the produced foams are considered for stability analysis. A sharp decrease of the half-life time and volume of the CGAs at NaCl concentrations larger than 20,000 ppm was observed, which was attributed to the precipitation of SDS in the solution. The mentioned SDS precipitation altered the dynamic surface tension behavior, dilational surface elasticity, and turbidity of the solution. The main reason for the precipitation of SDS is the increased Krafft point caused by the addition of salt. However, for the zwitterionic surfactant CAPB, the effects of added NaCl on the interfacial properties required for CGAs production was negligible due to the simultaneous effects on the cationic and anionic head groups in the CAPB leading to negligible changes in the net repulsion forces. Yet, an overall reduction in the half-life time of CGAs with increasing salt concentration, even when we have no precipitation, was observed for both surfactants, which could be explained by the reduction in the ability of XG to increase the viscosity with increasing salt concentration.

Keywords: Colloidal gas aphrons; foam formation and stability; drilling fluid; dynamic surface tension; interfacial rheology; cocoamidopropyl betaine; sodium dodecyl sulfate; NaCl

Related publications


Publ.-Id: 32199

Hydrodynamic data of an operational single-pass cross-flow sieve tray

Vishwakarma, V.
Researcher: Schleicher, Eckhard; ContactPerson: Schubert, Markus; Supervisor: Hampel, Uwe

The hydrodynamic data of a single-pass cross-flow sieve tray equipped in an air/water column mockup (0.8 m dia.) are provided here. The uploaded data were obtained after processing the two-phase dispersion data acquired by a novel multi-probe flow profiler. Effective froth height distribution, 3D liquid holdup distribution, and tracer-based data (i.e., appearance time distribution (ATD) parameters and liquid velocity map) are provided for the studied loadings.    

Keywords: column tray; two-phase cross-flow; hydrodynamics; effective froth height; 3D liquid holdup; tracer-based data

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-01-28
    DOI: 10.14278/rodare.775


Publ.-Id: 32198

Investigation of the structure and dynamics of Gallium binding to high-affinity peptides elucidated by multi- scale simulation, quantum chemistry, NMR and ITC

Taylor, C. J.; Schönberger, N.; Laníková, A.; Patzschke, M.; Drobot, B.; Žídek, L.; Lederer, F.

All simulation, quantum chemical, experimental and publication data for publication "Investigation of the structure and dynamics of Gallium binding to high-affinity peptides elucidated by multi- scale simulation, quantum chemistry, NMR and ITC"

Computational data is comprised of simulation inputs/outputs/trajectories/restarts and quantum chemical inputs/outputs for both peptides described in the paper (M3 and C3.15. 

Raw NMR data is uploaded to the Biological Magnetic Resonance Bank ( with accession numbers 50633-36. Outputs from post-processing are included here.

Raw ITC data is included here.

Publication data (04_GalliumPeptidesPCCP.tar.gz) is entirely in Latex.

Classical simulations: CHARMM 43b1
QMMM simulations: CHARMM 38b1/Turbomole 7.3.1
DFT: Turbomole 7.3.1

Keywords: QMMM; DFT; MD; ITC; NMR

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-01-28
    DOI: 10.14278/rodare.773
    License: CC-BY-4.0


Publ.-Id: 32196

HZDR Multiphase Addon for OpenFOAM

Schlegel, F.; Draw, M.; Evdokimov, I.; Hänsch, S.; Khan, H.; Lehnigk, R.; Meller, R.; Petelin, G.; Tekavčič, M.
Other: Couteau, Arthur; Other: Colombo, Marco; Other: Kriebitzsch, Sebastian; Other: Parekh, Jigar

The HZDR multiphase addon contains additional code for the open-source CFD software OpenFOAM, released by The OpenFOAM Foundation. The developments are dedicated to the numerical simulation of multiphase flows, in particular to the multi-field two-fluid model (Euler-Euler method). Within the OpenFOAM library the multiphaseEulerFoam framework is used for this type of simulation. The addon contains a modified multiphaseEulerFoam named HZDRmultiphaseEulerFoam with the full support of the HZDR baseline model set for polydisperse bubbly flows according to Liao et al. (Chem Eng Sci, 2019, Vol. 202, 55-69). In addition a solver dedicated to a hybrid modelling approach (dispersed and resolved interfaces, Meller et al., Int J Numer Meth Fluids. 2021, Vol. 93, 748-773) named cipsaMultiphaseEulerFoam is provided with the addon. This solver has an interface to the multiphaseEulerFoam framework and utilizes all available interfacial models of it.

General enhancements



  • morphology adaptive modelling framework for predicting dispersed and resolved interfaces based on Eulerian multi-field two-fluid model
  • compact momentum interpolation method according to Cubero et al. (Comput Chem Eng, 2014, Vol. 62, 96-107), including virtual mass
  • numerical drag according to Strubelj and Tiselj (Int J Numer Methods Eng, 2011, Vol. 85, 575-590) to describe resolved interfaces in a volume-of-fluid like manner
  • n-phase partial elimination algorithm for momentum equations to resolve strong phase coupling (Meller et al., Int J Numer Meth Fluids. 2021, Vol. 93, 748-773)
  • free surface turbulence damping for k-ω SST (symmetric and asymmetric damping, Frederix et al., Nucl Eng Des, 2018, Vol. 333, 122-130)
  • sub-grid scale modelling framework:
    • additional LES models for the unclosed convective sub-grid scale term
    • closure models for sub-grid surface tension term
  • configuration files and tutorials for easy setup of hybrid cases

Keywords: Multiphase Flow; Numerical Simulations; OpenFOAM; CFD; Finite volume method; Baseline model; Multi-field two-fluid model; Eulerian-Eulerian model; Momentum interpolation; Partial elimination algorithm; Free Surface

Related publications

  • Software in the HZDR data repository RODARE
    Publication date: 2021-01-26
    DOI: 10.14278/rodare.767
    License: GPL-3.0-only


Publ.-Id: 32194

Oriented Growth of In-Oxo Chain based Metal-Porphyrin Framework Thin Film for High-Sensitive Photodetector

Tian, Y.-B.; Vankova, N.; Weidler, P.; Kuc, A. B.; Heine, T.; Wöll, C.; Gu, Z.-G.; Zhang, J.

The potential of metal–organic frameworks (MOFs) for applications in optoelectronics results from a unique combination of interesting photophysical properties and the straightforward tunability using a large, ever growing set of organic and inorganic building units. Here, we demonstrate that using the MOF approach chromophores can be assembled into well-ordered 1D arrays using metal-oxo strands as lead structure. We demonstrate that the resulting porphyrinic rows exhibit unique photophysical properties and allow the realization of highly-sensitive photodetectors. A porphyrinic MOF thin film, SURMOF In-TCPP with [021] growth orientation, was fabricated using a layer-by-layer method, from In(NO3)3 and TCPP (5,10,15,20-(4-carboxyphenyl)porphyrin) linkers. A detailed experimental and theoretical analysis revealed that the assembly yields a structure where In-oxo strands running parallel to the substrate fix the chromophoric linkers in space to yield regular 1D arrays of porphyrins. The frontier orbitals of this highly anisotropic arrangement are localised in these columnar arrangements of porphyrins and give rise to a high photoactivity, which has been exploited to fabricate an efficient photodetector with a high responsivity of 7.28 × 1014 Jones for light with wavelength of 420 nm and short rise/fall times (0.10/0.05 s). This present work of oriented MOF thin film based high-sensitive photodetector for violet light provides a new avenue to combine the advantages of both inorganic and organic units for huge potential applications in optoelectronic devices.

Publ.-Id: 32191

Dynamics of Competitive Adsorption of Lipase and Ionic Surfactants at the Water–Air Interface

Javadi, A.; Dowlati, S.; Miller, R.; Schneck, E.; Eckert, K.; Kraume, M.

Lipase is one of the most important enzymes playing a key role in many biological and chemical processes, in particular for fat hydrolysis in living systems and technological applications such as food production, medicine, and biodiesel production. As lipase is soluble in water, the major hydrolysis process occurs at the water–oil interface, where lipase can get in contact with the oil. To provide optimum conditions, the emulsification of the oil is essential to provide a large interfacial area which is generally done by adding surfactants. However, the presence of surfactants can influence the lipase activity and also cause competitive adsorption, resulting in a removal of lipase from the interface or its conformational changes in the solution bulk. Here we have studied the dynamics of competitive adsorption and interfacial elasticity of mixed solutions containing lipase and the anionic surfactant sodium dodecyl sulfate (SDS) or the cationic surfactant cetyltrimethylammonium bromide (CTAB), respectively, at the water–air interface. The experiments were performed with a special coaxial double capillary setup for drop bulk–interface exchange developed for the drop profile analysis tensiometer PAT with two protocols: sequential and simultaneous adsorption of single components and mixed systems. The results in terms of dynamic surface tension and dilational viscoelasticity illustrate fast and complete desorption of a preadsorbed CTAB and SDS layers via subphase exchange with a buffer solution. In contrast, the preadsorbed lipase layer cannot be removed either by SDS or CTAB from the interface during drop bulk exchange with a buffer solution due to the unfolding process and conformation evolution of the protein molecules at the interface. In the opposite case, lipase can remove preadsorbed SDS and CTAB. The dynamic surface tension and viscoelasticity data measured before and after subphase exchange show joint adsorption of lipase and CTAB in the form of complexes, while SDS is adsorbed in competition with lipase. The results are in good correlation with the determined surface charges of the lipase gained by computational simulations which show a dominant negatively charged surface for lipase that can interact with the cationic CTAB while partial positively charged regions are observed for the interaction with the anionic SDS.

Related publications


Publ.-Id: 32189

Utilizing tailings material as strategic minerals and construction material

Dirlich, S.

The Polish-German joint project NOMECOR funded by the STAIR-II-program (BMBF, NCBR) investigated in the utilization of tailings material from a Polish flotation pond. The novel approach was to combine the valorization of strategic minerals with the utilization of the mineral compartments as construction material.
Conventional ammoniacal leaching combined with further processing steps has proven to be successful, while bioleaching was not really possible with the given composition of the material. In addition, the processing of the tailings material to be used as input material in cement production was also technically feasible.
The accompanying assessment of the innovative technologies in technological, environmental and economic respect, however, brought the conclusion that in particular the economic feasibility is not given with the proposed processing steps competing with very low deposition costs. At that stage the implementation concept was reconsidered to be more simplified using part of the tailings material directly after fractioning as construction material for building the dam, which was both technical and econmical feasible.

Keywords: remining; strategic minerals; construction material; tailings; remediation; resource management; resource technology

  • Invited lecture (Conferences) (Online presentation)
    Workshop Sustainable Mining, 06.10.2020, Lima, Peru

Publ.-Id: 32188

The surface expression of hydrocarbon seeps characterized by satellite image spectral analysis and rock magnetic data (Falcon basin, western Venezuela)

de La Rosa Ferna; Aldana, M.; Costanzo-Alvarez, V.; Yepez, S.; Amon, C.

Satellite images have been widely used to characterize mineral alteration zones in surface rocks affected by hydrocarbons’ upward seepage. Likewise, magnetic surveys over oil fields have been employed for similar purposes. This work integrates satellite image spectral analyses with rock magnetic and geochemical data (i.e., mass-specific magnetic susceptibility χ, saturation isothermal remanent magnetization SIRM, analysis of SIRM acquisition curves, absorption spectro-radiometry, and X-ray diffraction analyses). The target area was an oil- prospective region in northwestern Venezuela (Falcon Basin) swarmed by hydrocarbon seeps. The study’s main goal was to depict the spatial extension and vertical reach of the hydrocarbon-mediated alteration pro- duced by these seeps and gain some knowledge about the processes involved in the subsequent mineral changes. Multispectral and hyperspectral satellite images showed three hydrocarbon-induced diagenetic anomalies (HIDAs) associated with undifferentiated clays and kaolinite, and low dolomite content. A simple weathering model was suggested combining the likely effects of the ascending seepage of oil and gas with the seasonal alternation of leaching and evaporation of meteoric waters. This model explains the magnetic enhancement with depth due to Fe oxides and sulfides’ formation by reducing and oxidizing events. A non-supervised Two-Step Cluster Analysis (TSCA) was applied to integrate geochemical and rock magnetic properties with satellite images. The input variables were log SIRM and proxies of undifferentiated clays and dolomite concentrations obtained from the band-ratio ASTER images. The TSCA yields three clusters associated with different alteration levels in the top and low (0.3–1 m) soils and sediments. By mapping the class membership of each sampling site, for both depth levels, it was possible to obtain a broad view of the synergistic change of these combined properties, not only over the whole extent of the study area but also from top to bottom of the weathered sequence. This case study illustrates the potential of such an integrated method as an oil exploration tool, and a means to assess the level and scope of the environmental impact produced by hydrocarbon seepage on terrestrial ecosystems.

Keywords: Satellite remote sensing; Spectral images; Spectral signature; Hydrocarbon seeps; Hydrocarbon-induced diagenesis; Rock magnetism; Weathered sequence; Two-step cluster analysis

Related publications

Publ.-Id: 32187

Spatial and temporal evolution of the Freiberg epithermal Ag-Pb-Zn District, Germany

Swinkels, L.; Schulz-Isenbeck, J.; Frenzel, M.; Gutzmer, J.; Burisch, M.

The Freiberg district hosts one of the largest series of epithermal polymetallic vein deposits in Europe. Systematic sampling during historic mining provides an excellent opportunity to study the anatomy of these epithermal systems. Detailed petrographic investigations, geochemical analyses and fluid inclusion studies were conducted on several vertical profiles within the Freiberg district to decipher mineralogical and geochemical zoning patterns. Six distinctive mineral associations have been recognized within the Freiberg epithermal veins; sphalerite-pyrite-quartz and galena-quartz-carbonate associations are most abundant in the central sector, as well as the deepest sections of veins on the periphery of the district. A high-grade sphalerite-Ag-sulfides-carbonate association occurs laterally between the central and peripheral sectors, and at intermediate depth in veins on the periphery. Shallow and peripheral zones are dominated by an exceptionally Ag-rich Ag-sulfides-quartz association, whereas the shallowest veins locally comprise Ag-poor stibnite-quartz and quartz-carbonate associations. Fluid inclusion assemblages returned low salinities (<6.0 % eq. w(NaCl)), and homogenization temperatures successively decrease from ~320°C associated with the proximal and deep sphalerite-pyrite-quartz association, to ~170°C related to the distal and shallow Ag-sulfides-quartz association.

  • Poster
    DMG virtual poster session, 30.11.-03.12.2020, Online, Deutschland

Publ.-Id: 32185

Mineralogy and Fluid Characteristics of the Waschleithe Zn skarn – a distal part of the Schwarzenberg mineral system, Erzgebirge, Germany

Reinhardt, N.; Frenzel, M.; Meinert, L. D.; Gutzmer, J.; Kürschner, T.; Burisch, M.

The Waschleithe skarn is situated in the northern sector of the Schwarzenberg District in the western Erzgebirge (Germany), a district which hosts several large polymetallic skarn deposits. The Waschleithe is a Zn-dominant skarn comprising abundant dark Mn-rich hedenbergite, minor grandite garnet and magnetite related to the prograde stage, as well as epidote, quartz, fluorite, amphibole, chlorite, ilvaite, and Mn-rich pyroxenoids related to the retrograde stage of skarn formation. Ore minerals are related to the early retrograde stage and include sphalerite, galena, chalcopyrite, pyrite as well as minor amounts of scheelite and cassiterite. Fluid inclusion homogenization temperatures range from ∼385 to 360°C and from ∼320 to 285°C for the prograde and retrograde skarn stages, respectively. Thus, late-stage cooling is proposed as the major controlling factor for sulfide mineral precipitation. Fluid salinities for both stages are very low (< 3 % eq. w[NaCl]) and all observed fluid inclusion assemblages show homogeneous liquid-vapor ratios. Formation pressures >25 MPa suggest a minimum depth of formation of approximately 3 km. Oxygen fugacity during prograde skarn formation was initially low and increased towards the late prograde stage. The late-Variscan Eibenstock granite is identified as the most likely source of the skarn-forming fluids. The recognition of the Waschleithe skarn as a distal Zn skarn has major implications for the understanding of the Schwarzenberg District mineral system and provides valuable information for exploration targeting.


Publ.-Id: 32184

Introduction - Impact of Mining and Raw Materials on Society

Frenzel, M.

Short presentation on the importance of mining and raw materials for society.

  • Lecture (others) (Online presentation)
    2D3Dscopy Workshop on CT for partners, 27.11.2020, Online, Germany

Publ.-Id: 32183

Modelling indium deportment in a polymetallic sulfide ore - The case of Neves-Corvo, Portugal

Frenzel, M.; Bachmann, K.; Carvalho, J.; Relvas, J.; Pacheco, N.; Gutzmer, J.

There is a general lack of reliable quantitative data on the mineralogy and spatial distribution of indium and other by-product metals in ore deposits. This contribution showcases a new approach to integrate by-product metals into geometallurgical assessments. As an example, it uses the distribution and deportment of indium at Neves-Corvo, a major European base-metal mine (Cu + Zn). This study is the first to develop a quantitative model of indium deportment in volcanic hosted massive sulfide ores, demonstrating how regularities in indium partitioning between different minerals can be used to predict its mineralogical deportment in individual drill-core samples. Bulk-ore assays of As, Cu, Fe, Pb, S, Sb, Sn, Zn, and In are found to be sufficient for reasonably accurate predictions. The movement of indium through the ore processing plants is well explained by its mineralogical deportment, allowing for specific mine and process planning. The novel methodologies implemented in this contribution should be of general applicability to the geometallurgical assessment of many other byproduct metals in polymetallic sulfide ores, including Ga, Ge, Mo, Re, Se, Te, as well as the noble metals.

Keywords: Critical metals; Indium

  • Invited lecture (Conferences) (Online presentation)
    MGEI Annual Meeting, 19.-29.10.2020, Online, Indonesia

Publ.-Id: 32182

Development of a sampling protocol for the resource definition of sulphidic Cu-Zn-Pb tailings in an industrial tailings storage facility

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

Fine-grained residues of ore processing, known as tailings, are an inevitable product of metal production. Such tailings are typically stored in dedicated Tailings Storage Facilities (TSF). The sedimentary-style deposition of tailings within the TSF results in a structure of sub-horizontal, internally graded layers which heterogeneously concentrate the minerals comprising the residues. Primary depositional structures may be overprinted by subsequent chemical redistribution of minerals and elements during chemical reactions and metal mobilisation. Sulphidic tailings are problematic in terms of the potential for generation of Acid and Metalliferous Drainage, while providing interesting prospects for extraction of recoverable metals. However, efforts to build accurate and reproducible geospatial models of TSFs are hampered by a lack of understanding of how to sample heterogeneous tailings materials in a way that allows the effective characterisation of both the horizontal and vertical variability. This study introduces a sampling protocol for the resource characterisation of TSFs, following the Theory of Sampling. The Davidschacht TSF in Freiberg, Germany, was used as a case study. The Davidschacht TSF was deposited between 1944 and 1969; it contains around 760,000 m3 of Cu-Zn-Pb sulphidic flotation residues originating from the processing of polymetallic hydrothermal vein ores of the Freiberg mining district. A historical drilling campaign of 10 drill holes through the whole depth of the tailings provided a basis for the study. A second drilling campaign of 68 drill holes to a depth of 3 m was carried out on a 30 m grid, and nested grids of 15 m and 7.5 m in the centre of the TSF. The drill cores were logged and a bulk sample was collected for each 1 m section. Representative samples, with 10% randomly selected for duplication, will be analysed with X-Ray Fluorescence for chemical composition and sieving and laser diffraction for particle size distribution. The modal mineralogy, mineral associations and mineral liberation of selected samples will be assessed with the Scanning Electron Microscope-based Mineral Liberation Analyser. A detailed geospatial model of the surface zone of the tailings will be constructed to assess the intrinsic horizontal variability of the TSF. Comparison with the 3D model produced by the previous deep drilling campaign will determine if the sampling and modelling was sufficient to account for the variability of the tailings.

  • Open Access Logo Lecture (Conference) (Online presentation)
    European Geosciences Union General Assembly 2020, 04.05.2020, Wien, Austria

Publ.-Id: 32181

Data from a pilot plant experiment for the processing of a complex tin skarn ore - 19.11.2018

Schach, E.; Padula, F.; Buchmann, M.; Möckel, R.; Ebert, D.; Pereira, L.; Kern, M.; Leißner, T.; Pashkevich, D.; Sousa, R.; Bremerstein, I.; Breuer, B.; Oliver, K.; Seltmann, R.; Reimer, W.; Wotruba, H.; Filippov, L.; Peuker, U.; Rudolph, M.; Broadbent, C.; Roscher, M.; van den Boogaart, K. G.

This data set derives from a pilot plant campaign for the beneficiation of a complex tin bearing skarn ore, including different separation and classification steps. The aim of the pilot plant test work was to prove a flowsheet that had been developed based on detailed geometallurgical analysis and results from the research projects AFK (Aufbereitung feinkörniger Komplexerze, BMBF grant number 033R128) and FAME (European Union grant 641650) to produce a cassiterite concentrate for tin production, and further preconcentrates for iron, zinc, copper, indium, and arsenic. The tin mineralization is partially well localized in cassiterite, but also partially finely disseminated and thus unrecoverable as minor components in other minerals. The iron is located in magnetic and nonmagnetic iron oxides sometimes intergrown with cassiterite. Therefore, iron concentrates are recovered at larger grain sizes but need a further tin recovery step not implemented in the reported experiment. The other elements are mainly deported in sulfides, which are bulk recovered in a flotation step. A subsequent selective flotation is needed to recover them individually. This selective flotation is, however, not part of the reported experiment. The two tin concentrates recovered from the shaking table should be considered as preconcentrates, that can be enriched further e.g. through multi-stage gravity separation.

The motivation for this data set is to provide a consistent basis for the application of new particle based geometallurgical methods enabled by automated mineralogy (e.g. Buchmann et al. 2018; Schach et al. 2019; Buchmann et al. 2020; Pereira et al. 2020).

In addition, it should also allow for the comparison and evaluation of different analytical methods, which were used during the pilot plant experiments to generate a validated data set for the whole plant and to correlate different result from various methods. This is the basis for further investigations enabling the application of various analyzing methods in a synergetic way. Those synergies can help in the future to compensate drawbacks of certain methods by an adequate combination of multiple approaches.

This repository includes raw data and processed data from November 19, 2018. The following data is included:

  • X-ray fluorescence spectroscopy (XRF)
  • X-ray diffraction (XRD)
  • Automated Mineralogy (MLA)
  • The balanced mass flows and element/mineral grades for the XRF- and the MLA data
  • External certified analysis including different inductive coupled plasma (ICP) and XRF methods from ALS
  • R scripts for the mass balance

Please find further information in the "supplementary information" file

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-01-06
    DOI: 10.14278/rodare.714
    License: CC-BY-4.0


Publ.-Id: 32180

3D modelling of a mineral deposit using drill core hyperspectral data

de La Rosa Ferna; Khodadadzadeh, M.; Contreras Acosta, I. C.; Tusa, L.; Kirsch, M.; Tolosana Delgado, R.; Gloaguen, R.

Drill core samples have been traditionally used by the mining industry to make resource estimations and to build geological models. The hyperspectral drill core scanning has become a popular tool in mineral exploration because it provides a non-destructive method to rapidly characterise structural features, alteration patterns and rock mineralogy in a cost effective way.
Typically, the hyperspectral sensors cover a wide spectral range from visible and near- infrared (VNIR) to short and long wave infrared (SWIR and LWIR). The spectral features in this range will help to characterize a large number of mineral phases and complement the traditional core logging techniques. The hyperspectral core scanning provide mineralogical information in a millimetre scale for the entire borehole, which fills the gap between the microscopic scale of some of the laboratory analytical methods or the sparse chemical assays and the meter scale from the lithological descriptions.
However, applying this technique to the core samples of an entire ore deposit results in big datasets. Therefore, there is the need of a workflow to build a 3D geological model conditioned by the data with suitable data reduction methods and appropriate interpolation techniques.
This contribution presents a case study in the combination of traditional core logging and hyperspectral core logging for geological modelling. To attain mineral and alteration maps from the hyperspectral data unsupervised classification techniques were applied generating a categorical data set. The amount of data was reduced by the application of a domain generation algorithm based on the hyperspectral information. The domain generated by the algorithm is a compositional categorical data set that was then fed to condition the application of stochastic Plurigaussian simulations in the construction of 3D models of geological domains. This technique allows to simulate the spatial distribution of the hyperspectral derived categories, to make a resource estimation and to calculate its associated uncertainty.

Keywords: 3D modelling; Drill-core Hyperspectral data; Machine Learning; Mineral quantification

Publ.-Id: 32179

Tracing hydrothermal ore-forming processes - Recent developments in the use of sulfide trace-element signatures, and some thoughts for future research

Frenzel, M.

Over the past two decades, the advent of cheap LA-ICP-MS analyses has led to a veritable explosion of mineral trace-element data. However, this has not been accompanied by a commensurate increase in understanding of the geological factors that control mineral compositions. Thus, the great potential of this data to address problems in (economic) geology has remained largely untapped.
In this talk, I will briefly review the state-of-the-art for hydrothermal sulfide minerals. Following on from this, I will discuss a number of research questions that will need to be addressed to fully realize their potential in constraining the physical and chemical conditions of ore-formation.

Keywords: mineral chemistry; sphalerite; pyrite

  • Invited lecture (Conferences) (Online presentation)
    Ore Deposits Hub, 19.08.2020, Online, NA

Publ.-Id: 32178

In-situ Characterization of MoS2 Based Field Effect Transistors during Ion Irradiation

Hlawacek, G.; Fekri, Z.; Chava, P.; Erbe, A.

Here, in-situ Helium Ion Microscopy (HIM) has been used to electrically characterize single layer MoS 2 field effect transistors. These devices have been fabricated via chemical vapor deposition (CVD) and transferred onto SiO 2 /Si(p ++ ) chips for EBL contacting and further characterization. The oxide thickness is in the range of 200 nm to 300 nm.

Keywords: HIM; helium ion microscopy; MoS2; 2D materials

  • Open Access Logo Lecture (Conference) (Online presentation)
    M&M 2020 - Microscopy & Microanalysis, 03.-07.08.2020, Online, USA
    DOI: 10.1017/S1431927620014105
  • Lecture (Conference) (Online presentation)
    CMD2020GEFES, 31.08.-04.09.2020, Madrid, Spain

Publ.-Id: 32177

Assessment of inclined rotating fixed-bed reactors - Data of experiments and simulations

Timaeus, R.; Hampel, U.; Schubert, M.

This publication provides the data of a study executed with an inclined rotating fixed-bed reactor. Here, the hydrogenation of alpha-methylstyrene was investigated via experiments and simulations. In particular gas-limited reaction conditions were analyzed to reveal the potential of the reactor for process intensification. The space-time yield of the reactor was taken as performance measure and compared to a conventional trickle-bed reactor. The simulations were executed with a hybrid model, consisting of an Eulerian-Eulerian model and a heterogeneous continuum model.

Keywords: inclined rotating fixed-bed reactor; multiphase phase flow; CFD; process intensification

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-01-28
    DOI: 10.14278/rodare.761


Publ.-Id: 32176

Petawatt Femtosecond Laser Pulses from Titanium-Doped Sapphire Crystal

Kiriyama, H.; Pirozhkov, A. S.; Nishiuchi, M.; Fukuda, Y.; Sagisaka, A.; Kon, A.; Miyasaka, Y.; Ogura, K.; Dover, N. P.; Kondo, K.; Sakaki, H.; Koga, J. K.; Esirkepov, T. Z.; Huang, K.; Nakanii, N.; Kando, M.; Kondo, K.; Bock, S.; Ziegler, T.; Püschel, T.; Zeil, K.; Schramm, U.

Ultra-high intensity femtosecond lasers have now become excellent scientific tools for the study of extreme material states in small-scale laboratory settings. The invention of chirped-pulse amplification (CPA) combined with titanium-doped sapphire (Ti:sapphire) crystals have enabled realization of such lasers. The pursuit of ultra-high intensity science and applications is driving worldwide development of new capabilities. A petawatt (PW = 1015 W), femtosecond (fs = 10−15 s), repetitive (0.1 Hz), high beam quality J-KAREN-P (Japan Kansai Advanced Relativistic ENgineering Petawatt) Ti:sapphire CPA laser has been recently constructed and used for accelerating charged particles (ions and electrons) and generating coherent and incoherent ultra-short-pulse, high-energy photon (X-ray) radiation. Ultra-high intensities of 1022 W/cm2 with high temporal contrast of 10−12 and a minimal number of pre-pulses on target has been demonstrated with the J-KAREN-P laser. Here, worldwide ultra-high intensity laser development is summarized, the output performance and spatiotemporal quality improvement of the J-KAREN-P laser are described, and some experimental results are briefly introduced.

Publ.-Id: 32175

Demonstration of repetitive energetic proton generation by ultra-intense laser interaction with a tape target

Dover, N. P.; Nishiuchia, M.; Sakaki, H.; Kondo, K.; Lowe, H. F.; Alkhimova, M. A.; Ditter, E. J.; Ettlinger, O. C.; Faenov, A. Y.; Hata, M.; Hicks, G. S.; Iwata, N.; Kiriyama, H.; Koga, J. K.; Miyahara, T.; Najmudin, Z.; Pikuz, T. A.; Pirozhkov, A. S.; Sagisaka, A.; Schramm, U.; Sentoku, Y.; Watanabe, Y.; Ziegler, T.; Zeil, K.; Kando, M.; Kondo, K.

High power laser systems are an attractive driver for compact energetic ion sources. We demonstrate repetitive
acceleration at 0.1 Hz of proton beams up to 40 MeV from a reeled tape target irradiated by ultra-high intensities
up to 5 × 1021 Wcm 2 and laser energies ≈ 15 J using the J-KAREN-P laser system. We investigate the stability
of the source and its behaviour with laser spot focal size. We compare the scaling of proton energy with laser
energy to a recently developed analytical model, and also demonstrate that it is possible to reach energies up to
50 MeV on a single shot with a lower laser energy ≈ 10 J by using a thinner target, motivating development of
high repetition targetry suitable for thinner targets.


Publ.-Id: 32174

Dynamics of laser-driven heavy-ion acceleration clarified by ion charge states

Nishiuchi, M.; Dover, N.; Hata, M.; Sakaki, H.; Kondo, K.; Lowe, H.; Miyahara, T.; Kiriyama, H.; Koga, J.; Iwata, N.; Alkhimova, M.; Pirozhkov, A.; Faenov, A.; Pikuz, T.; Sagisaka, A.; Watanabe, Y.; Kando, M.; Ditter, E.; Ettlinger, O.; Hicks, G.; Najmudin, Z.; Ziegler, T.; Zeil, K.; Schramm, U.; Sentoku, Y.

Motivated by the development of next-generation heavy-ion sources, we have investigated the ionization and acceleration dynamics of an ultraintense laser-driven high-Z silver target, experimentally, numerically, and analytically. Using a novel ion measurement technique allowing us to uniquely identify silver ions, we experimentally demonstrate generation of highly charged silver ions (Z= 45+2−2 ) with energies of >20 MeV/nucleon (>2.2 GeV) from submicron silver targets driven by a laser with intensity 5 × 1021 W/cm 2 , with increasing ion energy and charge state for decreasing target thickness. We show that although target pre-expansion by the unavoidable rising edge of state-of-the-art high-power lasers can limit proton energies, it is advantageous for heavy-ion acceleration. Two-dimensional particle-in-cell simulations show that the Joule heating in the target bulk results in a high temperature (∼10 keV) solid density plasma, leading to the generation of high flux highly charged ions (Z= 40−2 +2, 10 MeV/nucleon) via electron collisional ionization, which are extracted and accelerated with a small divergence by an extreme sheath field at the target rear. However, with reduced target thickness this favorable acceleration is degraded due to the target deformation via laser hole boring, which accompanies higher energy ions with higher charge states but in an uncontrollable manner.
Our elucidation of the fundamental processes of high-intensity laser-driven ionization and ion acceleration provides a path for improving the control and parameters of laser-driven heavy-ion sources, a key component for next-generation heavy-ion accelerators.


Publ.-Id: 32173

High-Mobility Semiconducting Two-Dimensional Conjugated Covalent Organic Frameworks with p‑Type Doping

Wang, M.; Wang, M.; Lin, H.-H.; Ballabio, M.; Zhong, H.; Bonn, M.; Zhou, S.; Heine, T.; Canovas, E.; Dong, R.; Feng, X.

Two-dimensional conjugated covalent organic frameworks (2D c-COFs) are emerging as a unique class of semiconducting 2D conjugated polymers for (opto)electronics and energy storage. Doping is one of the common, reliable strategies to control the charge carrier transport properties, but the precise mechanism underlying COF doping has remained largely unexplored. Here we demonstrate molecular iodine doping of a metal−phthalocyanine-based pyrazine-linked 2D c-COF. The resultant 2D c-COF ZnPc-pz-I2 maintains its structural integrity and displays enhanced conductivity by 3 orders of magnitude, which is the result of elevated carrier concentrations. Remarkably, Hall effect measurements reveal enhanced carrier mobility reaching ∼22 cm2 V−1 s−1 for ZnPc-pz-I2, which represents a record value for 2D c-COFs in both the direct-current and alternatingcurrent limits. This unique transport phenomenon with largely increased mobility upon doping can be traced to increased scattering time for free charge carriers, indicating that scattering mechanisms limiting the mobility are mitigated by doping. Our work provides a guideline on how to assess doping effects in COFs and highlights the potential of 2D c-COFs to display high conductivities and mobilities toward novel (opto)electronic devices.

Publ.-Id: 32172

From research to clinical practice: a European neuroradiological survey on quantitative advanced MRI implementation

Manfrini, E.; Smits, M.; Thust, S.; Geiger, S.; Bendella, Z.; Petr, J.; Solymosi, L.; Keil, V. C.

Quantitative MRI (qMRI) methods provide versatile neuroradiological applications and are a hot topic in research. The degree of their clinical implementation is however barely known. This survey was created to illuminate which and how qMRI techniques are currently applied across Europe.

In total, 4753 neuroradiologists from 27 countries received an online questionnaire. Demographic and professional data, experience with qMRI techniques in the brain and head and neck, usage, reasons for/against application, and knowledge of the QIBA and EIBALL initiatives were assessed.

Two hundred seventy-two responders in 23 countries used the following techniques clinically (mean values in %): DWI (82.0%, n = 223), DSC (67.3%, n = 183), MRS (64.3%, n = 175), DCE (43.4%, n = 118), BOLD-fMRI (42.6%, n = 116), ASL (37.5%, n = 102), fat quantification (25.0%, n = 68), T2 mapping (16.9%, n = 46), T1 mapping (15.1%, n = 41), PET-MRI (11.8%, n = 32), IVIM (5.5%, n = 15), APT-CEST (4.8%, n = 13), and DKI (3.3%, n = 9). The most frequent usage indications for any qMRI technique were tissue differentiation (82.4%, n = 224) and oncological monitoring (72.8%, n = 198). Usage differed between countries, e.g. ASL: Germany (n = 13/63; 20.6%) vs. France (n = 31/40; 77.5%). Neuroradiologists endorsed the use of qMRI because of an improved diagnostic accuracy (89.3%, n = 243), but 50.0% (n = 136) are in need of better technology, 34.9% (n = 95) wish for more communication, and 31.3% need help with result interpretation/generation (n = 85). QIBA and EIBALL were not well known (12.5%, n = 34, and 11.0%, n = 30).

The clinical implementation of qMRI methods is highly variable. Beyond the aspect of readiness for clinical use, better availability of support and a wider dissemination of guidelines could catalyse a broader implementation.

Publ.-Id: 32171

Microresonators and Microantennas—tools to explore magnetization dynamics in single nanostructures

Cansever, H.; Lindner, J.

The phenomenon of magnetic resonance and its detection via microwave spectroscopy provide direct insight into the magnetization dynamics of bulk or thin film materials. This allows for direct access to fundamental properties, such as the effective magnetization, g-factor, magnetic anisotropy and the various damping (relaxation) channels that govern the decay of magnetic excitations. Cavity-based and broadband ferromagnetic resonance techniques that detect the microwave absorption of spin systems require a minimum magnetic volume to obtain a sufficient signal-to-noise ratio (S/N). Therefore, conventional techniques typically do not offer the sensitivity to detect individual micro- or nanostructures. A solution to this sensitivity problem is the so-called planar microresonator, which is able to detect even the tiniest absorption signals of magnetic nanostructures, including spin-wave or edge resonance modes. As an example, we describe the microresonator-based detection of spin-wave modes within microscopic strips of ferromagnetic A2 Fe60Al40 that are imprinted into a paramagnetic B2 Fe60Al40-matrix via focused ion-beam irradiation. While microresonators operate at a fixed microwave frequency, a reliable quantification of the key magnetic parameters like the g-factor or spin relaxation times requires investigations within a broad range of frequencies. In this study, we introduce and describe the step from microresonators towards a broadband microantenna approach. It allows for performing broadband magnetic resonance experiments on single nanostructured magnetic objects in a frequency range of 2-18 GHz. We employ this detection scheme to explore the influence of lateral structuring on the magnetization dynamics of a Permalloy strip.

Keywords: ferromagnetic resonance; microantenna; microresonator; magnetic relaxation; thin films; nanosctructures

Publ.-Id: 32170

Element-specific field-induced spin reorientation and tetracritical point in MnCr2S4

Yamamoto, S.; Suwa, H.; Kihara, T.; Nomura, T.; Kotani, Y.; Nakamura, T.; Scurschii, I.; Zherlitsyn, S.; Prodan, L.; Tsurkan, V.; Nojiri, H.; Loidl, A.; Wosnitza, J.

The ferrimagnetic spinel MnCr2S4 shows a variety of magnetic-field-induced phase transitions owing to bond frustration and strong spin-lattice coupling. However, the site-resolved magnetic properties at the respective field-induced phases in high magnetic fields remain elusive. Our soft x-ray magnetic circular dichroism studies up to 40 T directly evidence element-selective magnetic-moment reorientations in the field-induced phases. The complex magnetic structures are further supported by entropy changes extracted from magnetocaloric-effect measurements. Moreover, thermodynamic experiments reveal an unusual tetracritical point in the H-T phase diagram of MnCr2S4 due to strong spin-lattice coupling.


Publ.-Id: 32169

Investigation of the Field-Induced Phase Transitions in the (R,R)2Fe14B Rare-Earth Intermetallics in Ultrahigh Magnetic Fields

Kostyuchenko, N. V.; Tereshina, I. S.; Andreev, A. V.; Doerr, M.; Tereshina-Chitrova, E. A.; Paukov, M. A.; Gorbunov, D.; Politova, G. A.; Pyatakov, A. P.; Miyata, A.; Drachenko, O.; Zvezdin, A. K.; Portugall, O.

In this work, we perform a comparative study of the magnetization behavior of four series of compounds R2Fe14B and their hydrides R2Fe14BH5.5, and the compositions (Nd0.5R0.5)2Fe14B and their hydrides (Nd0.50.5)2Fe14BH5.5 with R and R´ = Ho, Er, and Tm. The magnetization is measured in pulsed magnetic fields up to 58 T and in megagauss fields up to 135 T at 5 K. The first and second critical fields of the field-induced transitions, Hc1 and Hc2 were estimated analytically and the results were verified against experimental data. We find that hydrogenation of R2Fe14B and (Nd0.50.5)2Fe14B reduces drastically the Hc1 and Hc2 values and, as a consequence, the intersublattice R–Fe exchange interaction parameter λ.

Publ.-Id: 32168

An Architecture for Interactive In Situ Visualization and its Transparent Implementation in OpenFPM

Gupta, A.; Incardona, P.; Deniz Aydin, A.; Gumhold, S.; Günther, U.; Sbalzarini, I. F.

Live in situ visualization of numerical simulations–interactive visualization while the simulation is running–can enable new modes of interaction, including computational steering. Designing easy-to-use distributed in situ architectures, with viewing latency low enough, and frame rate high enough, for interactive use, is challenging. Here, we propose a fully asynchronous, hybrid CPU–GPU in situ architecture that emphasizes interactivity. We also present a transparent implementation of this architecture embedded into the OpenFPM simulation framework. The benchmarks show that our architecture minimizes visual latencies, and achieves frame rates between 6 and 60 frames/second–depending on simulation data size and degree of parallelism–by changing only a few lines of an existing simulation code.

Keywords: In-situ visualisation; Simulations; OpenFPM; Supercomputing

  • Open Access Logo Contribution to proceedings
    ISAV'20 In Situ Infrastructures for Enabling Extreme-Scale Analysis and Visualization at SC'20, 12.11.2020, New York, NY, USA
    ISAV'20: ISAV'20 In Situ Infrastructures for Enabling Extreme-Scale Analysis and Visualization
    DOI: 10.1145/3426462.3426472

Publ.-Id: 32167

Investigation of the structure and dynamics of Gallium binding to high-affinity peptides elucidated by multi-scale simulation, quantum chemistry, NMR and ITC

Taylor, C. J.; Schönberger, N.; Laníková, A.; Patzschke, M.; Drobot, B.; Žídek, L.; Lederer, F.

Gallium is a Group IIIa metal and its recovery from wastewaters has become increasingly important for its reuse. The use of peptides for recycling offers a low-cost and environmentally-friendly option but the structural characteristics of peptides likely to bind Gallium are largely unknown. Multiple computational methods, coupled with experimental verification via NMR and Isothermal Calorimetry (ITC), were used to establish that gallium binds with high affinity to peptide sequences and to elucidate the structural characteristics that contributed. It was demonstrated that peptide pre-organisation is key to gallium binding and that a favourable binding position is necessarily governed by the size and shape of the electrostatic environment as much as individual electrostatic interactions with peptide residues themselves. Given favourable conditions, gallium retrieved plausible binding positions involving both charged and uncharged residues that greatly increases the range of bonding possibilities with other peptide sequences and offers insights for binding other metals. The addition of pH buffer substantially improved the affinity of gallium and a structural role for a buffer component was demonstrated.

Keywords: gallium; peptides; quantum chemistry; simulation; qmmm; isothermal titration calorimetry; NMR

Related publications

Publ.-Id: 32165

Analytical representation of the Local Field Correction of the Uniform Electron Gas within the Effective Static Approximation

Dornheim, T.; Moldabekov, Z.

The description of electronic exchange--correlation effects is of paramount importance for many applications in physics, chemistry, and beyond. In a recent Letter, Dornheim \textit{et al.} [\textit{Phys. Rev. Lett.}~\textbf{125}, 235001 (2020)] have presented the \emph{effective static approximation} (ESA) to the local field correction (LFC), which allows for the highly accurate estimation of electronic properties such as the interaction energy and the static structure factor. In the present work, we give an analytical parametrization of the LFC within ESA that is valid for any wave number, and available for the entire range of densities (0.7≤rs≤20) and temperatures (0≤θ≤4) that are relevant for applications both in the ground state and in the warm dense matter regime. A short implementation in Python is provided, which can easily be incorporated into existing codes.
In addition, we present an extensive analysis of the performance of ESA regarding the estimation of various quantities like the dynamic structure factor S(q,ω), static dielectric function ϵ(q), the electronically screened ion-potential Φ(r), and also stopping power in electronic medium. In summary, we find that the ESA gives an excellent description of all these quantities in the warm dense matter regime, and only becomes inaccurate when the electrons start to form a strongly correlated electron liquid (rs∼20). Moreover, we note that the exact incorporation of exact asymptotic limits often leads to a superior accuracy compared to the neural-net representation of the static LFC [\textit{J.~Chem.~Phys.}~\textbf{151}, 194104 (2019)].

Publ.-Id: 32164

Die Wirkung von sorbierten redoxaktiven Spezies auf Aluminiumoxid-Nanopartikeln bei der Immobilisierung von Technetium

Füssel, T.

This bachelor thesis studies the reduction of Tc(VII) to Tc(IV) by Mn²⁺ and Sn²⁺ when they are sorbed on the surface of alumina nanoparticles (heteroreduction). Several experimental approaches have been carried out to analyse the heteroreduction of Tc(VII) as a function of pH and ionic strength. It was shown that Tc(VII) heteroreduction is quantitative (100% of Tc is removed) when using Sn sorbed on alumina, whereas a maximum of 25% of Tc(VII) is uptaken when using Mn sorbed on alumina.

Keywords: Technetium; Alumina; Heteroreduction; Immobilization

  • Bachelor thesis
    TU Dresden, 2020
    Mentor: Prof. Dr. Thorsten Stumpf and Dr. Natalia Mayordomo
    44 Seiten

Publ.-Id: 32162

Magnetic field-induced phase transitions in antiferromagnetic rings

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

An emerging field of curvilinear magnetizm brings about new geometry-induced phenomena in usual magnetic materials, balancing between fundamental research, material sciences and technologies [1]. Modern technological advances allow to consider antiferromagnets (AFMs) as promising building blocks for spintronic and spin-orbitronic applications [2]. In this respect, curvilinear spin chains with AFM coupling are of fundamental interest as simplest systems possessing interplay between geometry and magnetic subsystem.
Here, we analyze the ground states of AFM ring with the nearest-neighbour Heisenberg exchange and strong single-ion anisotropy in the presence of external magnetic field, which is normal to the ring plane. We consider collinear two-sublattice 1D curved AFM spin chain with even number of spins. The hard axis of anisotropy is oriented tangentially to the chain. Within the classical continuum approach [3], its magnetic state is determined by the vector fields of Néel and ferromagnetism. In the ground state, the Néel vector is oriented perpendicularly to the ring plane (binormal state, see Fig.1) [3,4]. The magnetic field applied along the ring normal allows to observe spin-flop and spin-flip orientational phase transitions. We determine the dependency of spin-flop and spin-flip transition fields on the ring curvature. There is a critical curvature (κc), separating two topologically different ground states above spin-flop. The first one with the Néel order parameter within the normal plane is mainly determined by the anisotropy at small curvatures (normal state, see Fig.1). The second ground state at large curvatures is represented by oninon ordering of the Néel vector (onion state, see Fig.1). With the applied fields h>h0, Néel order parameter vanishes (ferromagnetic state). The phase diagram of AFM as a function of applied field intensity is presented in Fig.1: all analytical predictions are well-confirmed by the SLaSi spin-lattice simulations [5].

1] E.Vedmedenko et al, Journal of Physics D: Applied Physics 53, 453001(2020).
[2] V. Baltz et al, Reviews of Modern Physics 90, 015005 (2018)
[3] O. V. Pylypovskyi et al, Nano Letters 20, 8157 (2020)
[4] S. Castillo-Sepulveda et al, Physical Review B 96, 024426 (2017)
[5] [SLaSi spin–lattice simulations package]

Keywords: antiferromagnetism; curvilinear magnetism

  • Lecture (Conference) (Online presentation)
    XI Conference of young scientists "Problems in Theoretical Physics", 21.-23.12.2020, Kyiv, Ukraine

Publ.-Id: 32160

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