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39109 Publications

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

Permalink: https://www.hzdr.de/publications/Publ-32216
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

Permalink: https://www.hzdr.de/publications/Publ-32215
Publ.-Id: 32215


Characterization of lithium-ion batteries in recycling processes and assessment of the liberation efficiency of black mass components using automated mineralogy

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

Lithium-ion batteries (LIBs) are currently the most important electrochemical energy storage sys-tems for electronic mobile devices and electric vehicles. The growing global demand for LIBs is accompanied by an increase in the need for Co, Mn, Ni, Li and graphite. In order to narrow the gap between supply and demand and to achieve the European sustainability goals, the recycling of LiBs has attracted a lot of attention in recent years. Here, the focus is on valuable metals such as cobalt, nickel and lithium as well as graphite. In addition, due to its chemical and phase compositions, the battery material remains to be a huge challenge for a proper materials characterization. Hence, there is not only a need to find innovative and comprehensive LiB recycling process solutions but also to develop new analytical workflows to enhance the understanding of the battery material.
In this study, LIBs are fed to a mechanical and thermo-mechanical recycling process route to release active materials from electrodes foils. In addition to the valuable metals, the focus is particularly on the recovery of graphite. The mechanical route works with an impact shear crusher, while for the thermo-mechanical tests the batteries were vacuum pyrolyzed at 500-650 °C before crushing. The so-called black mass fraction smaller than 1 mm was separated and further classified into four size fractions. Accurate characterization of both the main chemistry and detailed characterization of the phases contained in the recycled material remains a major challenge. Therefore, each fraction has been characterized by different analytical methods, including X-ray fluorescence (XRF), inductively coupled plasma optical emission spectroscopy (ICP-OES). For a good visualization and quantifica-tion of the results of the processing success and process efficiency, a more detailed analytical char-acterization is required. This study proposes an innovative and novel characterization method based on automated mineralogy. Various important particle parameters such as size, composition and ad-hesion are analyzed and quantitatively evaluated. The Mineral Liberation Analyzer (MLA) system used for the measurements uses a combination of scanning electron microscopy (SEM) image analy-sis and energy-dispersive X-ray spectroscopy (EDS) and is established as a powerful method in the primary raw materials sector. However, there are no dedicated databases for use in the secondary raw materials sector in order to analyze black mass material in a fast and precise manner. An analyti-cal challenge of this study is therefore to create a database for battery characterization and to be able to use it for a wide range of applications.
Results of this study display a selective liberation of electrode foils during the beneficiation process. The thermo-mechanical process releases more active particles from the foils than a mechanical pro-cess alone. Hence, most of the graphite particles are liberated and concentrated in the < 63 μm frac-tion, in particular in the case of thermo-mechanically treated samples. Cu foils are generally better liberated than aluminium foils. 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 the mechanical process alone but Al breakage is more affected by thermal treatment, resulting in finer Al particles.

Keywords: Black mass; MLA; XRF; ICP-OES; Spent Lithium Ion Battery

  • Contribution to proceedings
    EMC 2021, 27.-30.06.2021, Salzburg, Austria

Permalink: https://www.hzdr.de/publications/Publ-32213
Publ.-Id: 32213


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

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Permalink: https://www.hzdr.de/publications/Publ-32212
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.

Permalink: https://www.hzdr.de/publications/Publ-32211
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

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Permalink: https://www.hzdr.de/publications/Publ-32210
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

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Permalink: https://www.hzdr.de/publications/Publ-32209
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

Permalink: https://www.hzdr.de/publications/Publ-32208
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

Permalink: https://www.hzdr.de/publications/Publ-32207
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

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Permalink: https://www.hzdr.de/publications/Publ-32206
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.

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Permalink: https://www.hzdr.de/publications/Publ-32205
Publ.-Id: 32205


Synergistic lanthanide extraction triggered by self-assembly of heterodinuclear Zn(II)/Ln(III) Schiff base/carboxylic acid complexes

Kelly, N.; Doert, T.; Hennersdorf, F.; Gloe, K.

The studies reported here focus on the extraction of La(III), Eu(III), and Yb(III) by chelating hexadentate 3-alkoxy-2-hydroxyphenyl substituted diimine ligands using the extraction system Ln(NO₃)₃–Zn(NO₃)₂–NaNO₃–buffer–H₂O/diimine-n-caprylic acid–CHCl₃. Significant synergistic enhancement has been observed for the Ln(III) extraction from nitrate media in the presence of Zn(II) and n-caprylic acid. These effects can be 15 interpreted by self-assembly of heterodinuclear Zn(II)/Ln(III) complexes with both deprotonated extractants in the organic phase taking into account solution and solid-state structural studies. The structures identified and the extraction behavior as well as the different factors influencing the process will be 20 discussed in detail. The goals of these experiments are to find preferred structure-extractability relationships for the synergistic systems investigated.

Keywords: Synergistic lanthanide extraction; Schiff base ligands; supramolecular chemistry; self-assembly of heterodinuclear Zn(II)/Ln(III) complexes; x-ray crystal structures

Permalink: https://www.hzdr.de/publications/Publ-32204
Publ.-Id: 32204


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

Permalink: https://www.hzdr.de/publications/Publ-32203
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

Permalink: https://www.hzdr.de/publications/Publ-32202
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

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Permalink: https://www.hzdr.de/publications/Publ-32201
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.

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Permalink: https://www.hzdr.de/publications/Publ-32200
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

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Permalink: https://www.hzdr.de/publications/Publ-32199
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

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Permalink: https://www.hzdr.de/publications/Publ-32198
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 (https://bmrb.io/) 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

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Permalink: https://www.hzdr.de/publications/Publ-32196
Publ.-Id: 32196


Fluorite-like hydrolyzed hexanuclear coordination clusters of Zr(IV) and Hf(IV) with syn-syn bridging N,N,N-trimethylglycine in soft crystal structures exhibiting cold-crystallization

Matsuoka, M.; Tsushima, S.; Takao, K.

Tetravalent metal ions are hydrolyzed under presence of N,N,N-trimethylglycine hydrochloride (betaine hydrochloride, [Hbet]Cl) in aqueous solutions to afford [M6(μ3-O)4(μ3-OH)4(μ-bet)8(κ-bet)4(H2O)4]12+ (M4+ = Zr4+ (1), Hf4+ (2)) as hydrated perchlorate salts. These compounds were characterized by single crystal X-ray diffraction, elemental analysis and IR spectroscopy. As a result, we have found that fluorite-like [M6O8] coordination clusters is formed through octahedral arrangement of six M4+ linked by μ3-O atoms. Additionally, each pair of neighboring M4+ are connected by the μ-bet ligand through a syn-syn bridging coordination of its carboxylate moiety. This interaction seems to prevent further growth of the fluorite structure leading to formation of MO2. It was difficult to directly distinguish each μ3-O atom to be μ3-OH− or μ3-O2− due to its strongly anisotropic thermal displacement in the obtained structures. Bond valence sum analysis suggested that four μ3-OH− and four μ3-O2− are alternately arranged in the [M6O8] core motifs. Indeed, such a symmetric structure of [M6(μ3-O)4(μ3-OH)4] was confirmed in another phase of 1 at 296 K, where 1 transforms to a monoclinic structure (1’). The number of ClO4− counteranions found in the structure determination is not enough to compensate +12 charge of [M6(μ3-O)4(μ3-OH)4(μ-bet)8(κ-bet)4(H2O)4]12+ in any unit cells of 1, 1’ and 2. Instead, large solvent/ion accessible voids have been actually observed in their crystal structures, indicating that the missing ClO4− are located there and significantly disordered to make them invisible in the crystallography.

Permalink: https://www.hzdr.de/publications/Publ-32195
Publ.-Id: 32195


HZDR Multiphase Addon for OpenFOAM

Schlegel, F.; Draw, M.; Evdokimov, I.; Hänsch, S.; Khan, H.; Lehnigk, R.; Meller, R.; Petelin, G.; Tekavčič, M.; Bilde, K. G.; Kamble, V. V.; Li, J.; Lyu, H.; Kota, S. P.
Other: Couteau, Arthur; Other: Colombo, Marco; Other: Haßlberger, Josef; Other: Kriebitzsch, Sebastian; Other: Kumaresh, Pramodh; Other: Parekh, Jigar; Other: Zhang, Tingting

The HZDR Multiphase Addon is a software publication released by Helmholtz-Zentrum Dresden-Rossendorf according to the FAIR principles (Findability, Accessibility, Interoperability, and Reuseability). It contains experimental research work 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).

Highlights of the provided addon are:

  • HZDR Baseline Model: HZDRMultiphaseEulerFoam solver with full support of the HZDR baseline model set for polydisperse bubbly flows, including configuration files and tutorials for simplified setup of Baseline cases (Hänsch et al., 2021).
  • Population Balance Modelling: A GPU-accelerated population balance method according to Petelin et al. (2021).
  • OpenFOAM-Hybrid cipsaMultiphaseEulerFoam solver featuring a hybrid modelling approach (dispersed and resolved interfaces, Meller et al., 2021) with an interface to the multiphaseEulerFoam framework to utilise all available interfacial models, and configuration files and tutorials for easy setup of hybrid cases.
  • more ...

Keywords: Multiphase Flow; Numerical Simulations; OpenFOAM; Computational Fluid Dynamics; Finite volume method; Baseline model; Multi-field two-fluid model; Euler-Euler method; Momentum interpolation; Partial elimination algorithm; Free Surface Flows; C++; C; CUDA; Shell; Python; Gnuplot

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Permalink: https://www.hzdr.de/publications/Publ-32194
Publ.-Id: 32194


Annual Report 2020 - Institute of Ion Beam Physics and Materials Research

Faßbender, J.; Helm, M.; Zahn, P.

As for everybody else also for the Institute of Ion Beam Physics and Materials Research (IIM), the COVID-19 pandemic overshadowed the usual scientific life in 2020. Starting in March, home office became the preferred working environment and the typical institute life was disrupted. After a little relaxation during summer and early fall, the situation became again more serious and in early December we had to severely restrict laboratory activities and the user operation of the Ion Beam Center (IBC). For the most part of 2020, user visits were impossible and the services delivered had to be performed hands-off. This led to a significant additional work load on the IBC staff. Thank you very much for your commitment during this difficult period. By now user operation has restarted, but we are still far from business as usual. Most lessons learnt deal with video conference systems, and everybody now has extensive experience in skype, teams, webex, zoom, or any other solution available. Conferences were cancelled, workshops postponed, and seminar or colloquia talks delivered online. Since experimental work was also impeded, maybe 2020 was a good year for writing publications and applying for external funding. In total, 204 articles have been published with an average impact factor of about 7.0, which both mark an all-time high for the Institute. 13 publications from last year are highlighted in this Annual Report to illustrate the wide scientific spectrum of our institute. In addition, 20 new projects funded by EU, DFG, BMWi/AiF and SAB with a total budget of about 5.7 M€ have started. Thank you very much for making this possible.
Also, in 2020 there have been a few personalia to be reported. Prof. Dr. Sibylle Gemming has left the HZDR and accepted a professor position at TU Chemnitz. Congratulations! The hence vacant position as the head of department was taken over by PD Dr. Artur Erbe by Oct. 1st. Simultaneously, the department has been renamed to “Nanoelectronics”. Dr. Alina Deac has left the institute in order to dedicate herself to new opportunities at the Dresden High Magnetic Field Laboratory. Dr. Matthias Posselt went to retirement after 36 years at the institute. We thank Matthias for his engagement and wish him all the best for the upcoming period of his life.
However, also new equipment has been setup and new laboratories founded. A new 100 kV accelerator is integrated into our low energy ion nanoengineering facility and complements our ion beam technology in the lower energy regime. This setup is particularly suited to perform ion implantation into 2D materials and medium energy ion scattering (MEIS).
Finally, we would like to cordially thank all partners, friends, and organizations who supported our progress in 2020. First and foremost we thank the Executive Board of the Helmholtz-Zentrum Dresden-Rossendorf, the Minister of Science and Arts of the Free State of Saxony, and the Ministers of Education and Research, and of Economic Affairs and Energy of the Federal Government of Germany. Many partners from univer¬sities, industry and research institutes all around the world contributed essentially, and play a crucial role for the further development of the institute. Last but not least, the directors would like to thank all members of our institute for their efforts in these very special times and excellent contributions in 2020.

Related publications

  • Open Access Logo Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-112 2021
    ISSN: 2191-8708, eISSN: 2191-8716

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Permalink: https://www.hzdr.de/publications/Publ-32192
Publ.-Id: 32192


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.

Permalink: https://www.hzdr.de/publications/Publ-32191
Publ.-Id: 32191


Overcoming finite-size effects in electronic structure simulations at extreme conditions

Dornheim, T.; Vorberger, J.

Ab initio quantum Monte Carlo (QMC) methods in principle allow for the calculation of exact properties of correlated many-electron systems, but are in general limited to the simulation of a finite number of electrons N in periodic boundary conditions. Therefore, an accurate theory of finite-size effects is indispensable to bridge the gap to realistic applications in the thermodynamic limit. In this work, we revisit the uniform electron gas (UEG) at finite temperature as it is relevant to contemporary research e.g. in the field of warm dense matter. In particular, we present a new scheme to eliminate finite-size effects both in the static structure factor S(q) and in the interaction energy v, which is based on the density response formalism. We demonstrate that this method often allows to obtain v in the TDL within a relative accuracy of ∼0.2% from as few as N=4 electrons without any empirical choices or knowledge of results for other values of N. Finally, we evaluate the applicability of our method upon increasing the density parameter rs and decreasing the temperature T.

Permalink: https://www.hzdr.de/publications/Publ-32190
Publ.-Id: 32190


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.

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Permalink: https://www.hzdr.de/publications/Publ-32189
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

Permalink: https://www.hzdr.de/publications/Publ-32188
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

Permalink: https://www.hzdr.de/publications/Publ-32187
Publ.-Id: 32187


Li-Co-Ni-Mn-REE veins of the Western Erzgebirge, Germany - A potential source of battery raw materials

Burisch, M.; Frenzel, M.; Seibel, H.; Gruber, A.; Oelze, M.; Pfänder, J. A.; Sanchez-Garrido, C.; Gutzmer, J.

Situated in the western Erzgebirge metallogenetic province (Vogtland, Germany) the Eichigt prospect is associated with several hydrothermal quartz veins that are exposed at surface. Bulk-rock geochemical assays of colloform Fe- and Mn-oxide aggregates associated with these veins yield high concentrations of Li (0.6-4.1 kg/t), Co (0.6-14.7kg/t) and Ni (0.2-2.8 kg/t), as well as significant quantities of Mn, Cu and light rare earth elements, a very unusual metal tenor closely resembling the mixture of raw materials needed for Li-ion battery production. This study reports the results of a first detailed investigation of this rather unique polymetallic mineralization style, including detailed petrographic and mineralogical studies complemented by bulk rock geochemistry, electron microprobe analyses and laser-ablation inductively-coupled massspectrometry. The mineralized material comprises of an oxide assemblage of goethite and hematite, hollandite and lithiophorite that together cement angular fragments of vein quartz. Lithiophorite is the predominant host of Li (3.6-11.1 kg/t), Co (2.5-54.5 kg/t) and Ni (0.2-8.9 kg/t); Cu is contained in similar amounts in hollandite and lithiophorite whereas LREE are hosted mostly in microcrystalline rhabdophane and florencite finely intergrown with the Mn oxyhydroxides. 40Ar/39Ar ages (~40-34 Ma) of manganomelane link the polymetallic oxyhydroxide mineralization to geothermal
activity associated with Cenozoic opening of the Eger rift system. A low temperature hydrothermal overprint of pre-existing base metal sulfide-quartz mineralization on fault structures that were reactivated during continental rifting is thus identified as the most likely origin of the polymetallic oxyhydroxide mineralization at Eichigt. A mixture of metal remobilization from precursor metal sulfide mineralization and/or leaching of crustal rocks may have given rise to the unusual metal tenor.

Permalink: https://www.hzdr.de/publications/Publ-32186
Publ.-Id: 32186


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.

Permalink: https://www.hzdr.de/publications/Publ-32185
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.

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Permalink: https://www.hzdr.de/publications/Publ-32184
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

Permalink: https://www.hzdr.de/publications/Publ-32183
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

Permalink: https://www.hzdr.de/publications/Publ-32182
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

Permalink: https://www.hzdr.de/publications/Publ-32181
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

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Permalink: https://www.hzdr.de/publications/Publ-32180
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

Permalink: https://www.hzdr.de/publications/Publ-32179
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

Permalink: https://www.hzdr.de/publications/Publ-32178
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

Related publications

  • 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

Permalink: https://www.hzdr.de/publications/Publ-32177
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

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Permalink: https://www.hzdr.de/publications/Publ-32176
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.

Permalink: https://www.hzdr.de/publications/Publ-32175
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.

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Permalink: https://www.hzdr.de/publications/Publ-32174
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.

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Permalink: https://www.hzdr.de/publications/Publ-32173
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.

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Permalink: https://www.hzdr.de/publications/Publ-32172
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.

Objective
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.

Methods
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.

Results
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).

Conclusions
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.

Permalink: https://www.hzdr.de/publications/Publ-32171
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

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Permalink: https://www.hzdr.de/publications/Publ-32170
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.

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Permalink: https://www.hzdr.de/publications/Publ-32169
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.

Permalink: https://www.hzdr.de/publications/Publ-32168
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
    Cited 2 times in Scopus

Permalink: https://www.hzdr.de/publications/Publ-32167
Publ.-Id: 32167


SNT: A Unifying Toolbox for Quantification of Neuronal Anatomy

Arshadi, C.; Günther, U.; Eddison, M.; Harrington, K. I. S.; Ferreira, T. A.

Quantification of neuronal morphology is essential for understanding neuronal connectivity and many software tools have been developed for neuronal reconstruction and morphometry. However, such tools remain domain-specific, tethered to specific imaging modalities, and were not designed to accommodate the rich metadata generated by recent whole-brain cellular connectomics. To address these limitations, we created SNT: a unifying framework for neuronal morphometry and analysis of single-cell connectomics for the widely used Fiji and ImageJ platforms. We demonstrate that SNT can be used to tackle important problems in contemporary neuroscience, validate its utility, and illustrate how it establishes an end-to-end platform for tracing, proof-editing, visualization, quantification, and modeling of neuroanatomy. With an open and scriptable architecture, a large user base, and thorough community-based documentation, SNT is an accessible and scalable resource for the broad neuroscience community that synergizes well with existing software.

Keywords: Neuroanatomy; Morphology; Connectomics; Software; Neuroscience

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Permalink: https://www.hzdr.de/publications/Publ-32166
Publ.-Id: 32166


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

Permalink: https://www.hzdr.de/publications/Publ-32165
Publ.-Id: 32165


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

Dornheim, T.; Moldabekov, Z.; Tolias, P.

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)].

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Permalink: https://www.hzdr.de/publications/Publ-32164
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

Permalink: https://www.hzdr.de/publications/Publ-32162
Publ.-Id: 32162


An open-source population balance modeling framework for the simulation of polydisperse multiphase flows

Lehnigk, R.; Bainbridge, W.; Liao, Y.; Lucas, D.; Niemi, T.; Peltola, J.; Schlegel, F.

Polydispersity is a challenging feature of many industrial and environmental multiphase flows, influencing all related transfer and transport processes. Besides their size, the fluid or solid particles may be distributed with respect to other properties such as their velocity or shape. Here, a population balance model based on the method of classes is combined with a multifluid solver within the open source Computational Fluid Dynamics library OpenFOAM. The model allows for tracking the evolution of one or more size-conditioned secondary properties. It is applied to two different problems, the first being bubbly flow of air and water in a vertical pipe, where considering the velocity as a secondary property allows to resolve the size-dependent radial segregation. The second application is the gas phase synthesis of titania powder, where non-spherical particle aggregates appear whose shape is modeled through a collision diameter, leading to an improved prediction of the size distribution.

Keywords: Computational fluid dynamics (CFD); OpenFOAM; Multiphase flow; Population balance modeling; Method of classes

Permalink: https://www.hzdr.de/publications/Publ-32161
Publ.-Id: 32161


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

Permalink: https://www.hzdr.de/publications/Publ-32160
Publ.-Id: 32160


The PSMA-11-derived hybrid molecule PSMA-914 specifically identifies prostate cancer by preoperative PET/CT and intraoperative fluorescence imaging

Eder, A.; Omrane, M.; Stadlbauer, S.; Roscher, M.; Khoder, W.; Gratzke, C.; Kopka, K.; Eder, M.; Meyer, P.; Jilg, C.; Ruf, J.

Resection of tumor tissue represents one of the standard curative treatment options for the clinical management of prostate cancer. However, intraoperative localization and precise delineation of malignant tissue from surrounding healthy structures still remain challenging. The development of PSMA-targeting hybrid molecules enabling the pre- and intraoperative detection of tumor tissue supported by both radioactivity (e.g., using DROP-IN technology) and fluorescence might help to overcome these limitations. Here, we report for the first time preoperative PET/CT imaging and subsequent fluorescence-guided surgery aided by a PSMA-11-derived peptidomimetic PSMA-targeting hybrid molecule.

Permalink: https://www.hzdr.de/publications/Publ-32159
Publ.-Id: 32159


Telemedicine pre and post COVID-19: Lessons for commercialization based on previous use cases

Ferenczi, G. L.; Mahmood, A.; Bergmann, R.

Telemedicine used to be slow, difficult, expensive and widely neglected by doctors and patients. COVID-19 changed everything; telemedicine is entering a period of rapid economic and business growth. This paper discusses the reasons for change in telemedicine over the last 20 years, through real-life medical technology projects, telemetry, ehealth and health IT. Our methods are based on the analysis of telemedicine projects we have implemented and characteristic historical data. The results of our investigation demonstrate a clear increase of significance in telemedicine in the present and near future. We envision the evolution of mobile phones to personal telehealth monitors. Prior to COVID-19, market penetration and economic factors of telemedicine evolved slowly and in an uneven manner on a global scale. Many of the projects remained active only as long as the grant or corporate or national support was provided. The age of novel globally spreading infectious diseases, exemplified by COVID-19, has created an unusual, different setting. Recent pandemics and epidemics have changed global economics significantly and generated a new motivation and a new market with a projected trillion- dollar market value. Post COVID-19, regular and periodic epidemics and pandemics are expected to continue to occur. This will generate an enormous global market for isolated high-tech services, including telemedicine and telemetry.

Keywords: COVID-19; telemedicine; health system; respiratory diagnostics; cardiology

  • Open Access Logo Journal of the International Society for Telemedicine and eHealth 8(2020), e8
    DOI: 10.29086/JISfTeH.8.e8

Permalink: https://www.hzdr.de/publications/Publ-32158
Publ.-Id: 32158


Particle Stiffness and Surface Topography Determine Macrophage‐Mediated Removal of Surface Adsorbed Particles

Lee, A.; Septiadi, D.; Taladriz-Blanco, P.; Almeida, M.; Haeni, L.; Spuch-Calvar, M.; Abdussalam, W.; Rothen-Rutishauser, B.; Petri-Fink, A.

Cellular surface recognition and behavior are driven by a host of physical and chemical features which have been exploited to influence particle–cell interactions. Mechanical and topographical cues define the physical milieu which plays an important role in defining a range of cellular activities such as material recognition, adhesion, and migration through cytoskeletal organization and signaling. In order to elucidate the effect of local mechanical and topographical features generated by the adsorption of particles to an underlying surface on primary human monocyte‐derived macrophages (MDM), a series of poly(N‐isopropylacrylamide) (pNIPAM) particles with differing rigidity are self‐assembled to form a defined particle‐decorated surface. Assembly of particle‐decorated surfaces is facilitated by modification of the underlying glass to possess a positive charge through functionalization using 3‐aminopropyltriethoxysilane (APTES) or coating with poly(L‐lysine) (PLL). MDMs are noted to preferentially remove particles with higher degrees of crosslinking (stiffer) than those with lower degrees of crosslinking (softer). Alterations to the surface density of particles enabled a greater area of the particle‐decorated surface to be cleared. Uniquely, the impact of particle adsorption is evinced to have a direct impact on topographical recognition of the surface, suggesting a novel approach for controllably affecting cell‐surface recognition and response.

Permalink: https://www.hzdr.de/publications/Publ-32157
Publ.-Id: 32157


Quantum disordered state in the J1-J2 square-lattice antiferromagnet Sr2Cu(Te0.95W0.05)O6

Yoon, S.; Lee, W.; Lee, S.; Park, J.; Lee, C. H.; Choi, Y. S.; Do, S.-H.; Choi, W.-J.; Chen, W.-T.; Chou, F.; Gorbunov, D.; Oshima, Y.; Ali, A.; Singh, Y.; Berlie, A.; Watanabe, I.; Choi, K.-W.

The B-site ordered double perovskites Sr2Cu(Te1−xWx)O6 provide an excellent arena for investigating exotic phases expected for the J1-J2 square-lattice Heisenberg antiferromagnet. Here, combining magnetic susceptibility and specific-heat measurements with electron spin resonance (ESR) and muon spin rotation/relaxation (μSR) techniques, we explore a spin-liquid-like state in the vicinity of the Néel critical end point (x = 0.05–0.1). The specific heat and the ESR and muon relaxation rates give evidence for an energy hierarchy of low-energy excitations, reminiscent of randomness-induced singlet states. In addition, the weak transverse μSR data show a fraction of frozen magnetic moments in the random-singlet background. The origin of a random-singlet-like state near the phase boundary is discussed in terms of concomitant exchange randomness and local strain generated by the W6+-for-Te6+ substitution.

Permalink: https://www.hzdr.de/publications/Publ-32156
Publ.-Id: 32156


Emergence of Frustrated Short-Range Order above Long-Range Order in the S = 1/2 Kagome Antiferromagnet CaCu3(OD)6Cl2·0.6D2O

Ihara, Y.; Matsui, K.; Kohama, Y.; Luther, S.; Opherden, D.; Wosnitza, J.; Kühne, H.; Yoshida, H. K.

We report on the low-energy dynamics in the kagome antiferromagnet CaCu3(OD)6Cl2·0.6D2O (Ca-kapellasite) as studied by use of 2D-NMR measurements. Previous 35Cl-NMR measurements revealed that the nuclear spin–lattice relaxation rate (1/T1) shows two peaks at temperatures, T* = 7.2 K and Ts ≃ 25 K. While the low-temperature peak at T* is ascribed to the critical fluctuations near the long-range magnetic ordering, the origin of the high-temperature peak has not been fully understood. From the 1/T1 measurements on the D sites at the OD groups (DOD), we find no peak at Ts, evidencing that the high-temperature peak is not related to the molecular dynamics of the OD groups. We discuss the possibility of a frustration-induced short-range ordered state below Ts before the long-range order is stabilized by the Dzyaloshinskii–Moriya interaction. We also observed static internal fields at the DOD site in the long-range ordered state below T*, and confirm the previously proposed negative-chirality q = 0 magnetic structure.

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Permalink: https://www.hzdr.de/publications/Publ-32155
Publ.-Id: 32155


A new prognostic hypoxia biomarker consisting of imaging and gene-based data.

Thomas, E.; Krause, M.

In the research article of EBioMedicine [1], Fjeldbo and colleagues developed a combined biomarker based on hypoxic fraction from dynamic contrast enhanced (DCE)-MRI imaging and genetic data of cervical cancer. They were able to predict the response to radiochemotherapy of these patients. The patients were divided into groups less or more hypoxic, based on a previously defines cut-off for the gene-based biomarkers (6 hypoxia-related genes) [2]. In the same group of 41 patients, a cut-off for the imaging biomarker was newly assessed by analyzing DCE-MRI data and using ABrix-images as parameter for the hypoxic fraction. In the next step these cut-offs were validated in 77 patients and subsequently a combined hypoxic biomarker was generated. The combination of the biomarkers revealed the same hypoxic status in 75% of the 118 patients. Therefore, besides the more and less hypoxic group, a third group with different hypoxia status was constituted.

Permalink: https://www.hzdr.de/publications/Publ-32154
Publ.-Id: 32154


Achieving Sustainable Development Goals in rare earth magnets production: A review on state of the art and SWOT analysis

Canal Bonfante, M.; Prats Raspini, J.; Belo Fernandes, I.; Fernandes, S.; Campos, L. M. S.; Estevam Alarcon, O.

Rare Earth Magnets (REM), especially the NdFeB type, are essential components in high-performance electric motors and wind turbines, playing an important role in the shift towards a low-carbon energy matrix. However, little work has been done to understand how the production of REM can be in line with the global sustainable transition. To overcome this lack and help with future research, as well as decision-making, this paper provides a literature overview of which aspects of sustainability are being investigated in the REM supply chain, and how each of them contributes to achieving Sustainable Development Goals (SDG). This research is developed through a consistent analysis of 44 peer-reviewed publications, followed by an analysis of strengths, weaknesses, opportunities, and threats. Four main subjects of studies were identified: environmental impact; social impact; economic aspects and circular economy. Most of the studies focus on computing the environmental impact through life cycle assessment and discussing techniques towards exploring the circular economy concept. In addition to contributing to a greener economy, the majors identified strengths of REM are the great potential of its supply chain in reducing primary resource extraction, since REM recovery and recycling seem to be viable, and the promising techniques to minimize environmental impacts along the rare earth elements production chain.

Keywords: NdFeB; Energy resources; Energy transition; Rare earth; Sustainable development goals; Critical review

Permalink: https://www.hzdr.de/publications/Publ-32153
Publ.-Id: 32153


First application of a high-resolution silicon detector for proton beam Bragg peak detection in a 0.95 T magnetic field

Causer, T. J.; Schellhammer, S.; Gantz, S.; Lühr, A.; Hoffmann, A. L.; Metcalfe, P. E.; Rosenfeld, A. B.; Guatelli, S.; Petasecca, M.; Oborn, B. M.

Purpose: To report on experimental results of a high spatial resolution silicon-based detector exposed to therapeutic quality proton beams in a 0.95 T transverse magnetic field. These experimental results are important for the development of accurate and novel dosimetry methods in future potential real-time MRI-guided proton therapy systems.
Methods: A permanent magnet device was utilized to generate a 0.95 T magnetic field over a 4 9 20 9 15 cm3 volume. Within this volume, a high-resolution silicon diode array detector was positioned inside a PMMA phantom of 4 9 15 9 12 cm3. This detector contains two orthogonal strips containing 505 sensitive volumes spaced at 0.2 mm apart. Proton beams collimated to a circle of 10 mm diameter with nominal energies of 90 MeV, 110 MeV, and 125 MeV were incident on the detector from an edge-on orientation. This allows for a measurement of the Bragg peak at 0.2 mm spatial resolution in both the depth and lateral profile directions. The impact of the magnetic field on the proton beams, that is, a small deflection was also investigated. A Geant4 Monte Carlo simulation was performed of the experimental setup to aid in interpretation of the results.
Results: The nominal Bragg peak for each proton energy was successfully observed with a 0.2 mm spatial resolution in the 0.95 T transverse magnetic field in both a depth and lateral profiles. The proton beam deflection (at 0.95 T) was a consistent 2 +-0.5 mm at the center of the magnetic volume for each beam energy. However, a pristine Bragg peak was not observed for each energy. This was caused by the detector packaging having small air gaps between layers of the phantom material surrounding the diode array. These air gaps act to degrade the shape of the Bragg peak, and further to this, the nonwater equivalent silicon chip acts to separate the Bragg peak into multiple peaks depending on the proton path taken. Overall, a promising performance of the silicon detector array was observed, however, with a qualitative assessment rather than a robust quantitative dosimetric evaluation at this stage of development.
Conclusions: For the first time, a high-resolution silicon-based radiation detector has been used to measure proton beam Bragg peak deflections in a phantom due to a strong magnetic field. Future efforts are required to optimize the detector packaging to strengthen the robustness of the dosimetric quantities obtained from the detector. Such high-resolution silicon diode arrays may be useful in future efforts in MRI-guided proton therapy research.

Keywords: magnetic deflection; magnetic field; MRI-guided proton therapy; proton beam; silicon detectors

Permalink: https://www.hzdr.de/publications/Publ-32152
Publ.-Id: 32152


Radiotherapy and COVID-19-everything under control or just the start of a long story?

Nestle, U.; Krause, M.

This pandemic is an imposition! We all are exhausted by repeated discussions on the current situation. Would like to be “back to normal”—whatever that might be—very soon.
Unfortunately, this is still a dream and we are in the middle of the corona reality. Almost forgotten: the initial panic that radiooncology could no longer operate according to law under pandemic conditions was quickly and effectively countered by an unprecedented concerted response from the authorities.
Then we had all these practical questions: How to deal with potentially limited personnel resources? How to treat potentially infected patients in routine care? To this end, at a very early stage, the German Society for Radiooncology (DEGRO), together with the Working Group for Radiooncology (ARO) of the German Cancer Society and the National Association of German Radiotherapists (BVDST), compiled two helpful statements and recommendations [1–3].
At a previously unimagined speed, we then dealt with hygiene concepts, made friends with hypofractionation, optimized our workflow, discussed home office solutions, formed staff groups, and reorganized the aftercare outpatient clinics. In their interesting survey in this issue, Matuschek et al. report on how well all this has worked out [4]. Overall, in Germany, only a relatively small number of COVID-positive patients have had to be treated by radiotherapy so far. We will see how the situation will develop during the remainder of this year. At least we are very well prepared—both with concepts and organizational skills—for higher infection rates.

Permalink: https://www.hzdr.de/publications/Publ-32151
Publ.-Id: 32151


3D Cell Culture-Based Global miRNA Expression Analysis Reveals miR-142-5p as a Theranostic Biomarker of Rectal Cancer Following Neoadjuvant Long-Course Treatment.

Kunigenas, L.; Stankevicius, V.; Dulskas, A.; Budginaite, E.; Alzbutas, G.; Stratilatovas, E.; Cordes, N.; Suziedelis, K.

Altered expression of miRNAs in tumor tissue encourages the translation of this specific molecular pattern into clinical practice. However, the establishment of a selective biomarker signature for many tumor types remains an inextricable challenge. For this purpose, a preclinical experimental design, which could maintain a fast and sensitive discovery of potential biomarkers, is in demand.
The present study suggests that the approach of 3D cell cultures as a preclinical cancer model that is characterized to mimic a natural tumor environment maintained in solid tumors could successfully be employed for the biomarker discovery and validation. Subsequently, in this study, we investigated an environment-dependent miRNA expression changes in colorectal adenocarcinoma DLD1 and HT29 cell lines using next-generation sequencing (NGS) technology. We detected a subset of 16 miRNAs differentially expressed in both cell lines cultivated in multicellular spheroids compared to expression levels in cells grown in 2D. Furthermore, results of in silico miRNA target analysis showed that miRNAs, which were differentially expressed in both cell lines grown in MCS, are involved in the regulation of molecular mechanisms implicated in cell adhesion, cell-ECM interaction, and gap junction pathways. In addition, integrins and platelet-derived growth factor receptors were determined to be the most significant target genes of deregulated miRNAs, which was concordant with the environment-dependent gene expression changes validated by RT-qPCR. Our results revealed that 3D microenvironment-dependent deregulation of miRNA expression in CRC cells potentially triggers essential molecular mechanisms predominantly including the regulation of cell adhesion, cell–cell, and cell–ECM interactions important in CRC initiation and development. Finally, we demonstrated increased levels of selected miR-142-5p in rectum tumor tissue samples after neoadjuvant long course treatment compared to miR-142-5p expression levels in tumor biopsy samples collected before the therapy. Remarkably, the elevation of miR-142-5p expression remained in tumor samples compared to adjacent normal rectum tissue as well. Therefore, the current study provides valuable insights into the molecular miRNA machinery of CRC and proposes a potential miRNA signature for the assessment of CRC in further clinical research.

Keywords: colorectal carcinoma; rectal cancer; 3D cell culture; miRNA; tumor microenvironment; cell adhesion; cancer biomarkers; neoadjuvant therapy; miR-142

Permalink: https://www.hzdr.de/publications/Publ-32150
Publ.-Id: 32150


Comparison of GeneChip, nCounter, and Real-Time PCR-Based Gene Expressions Predicting Locoregional Tumor Control after Primary and Postoperative Radiochemotherapy in Head and Neck Squamous Cell Carcinoma

Schmidt, S.; Linge, A.; Grosser, M.; Lohaus, F.; Gudziol, V.; Nowak, A.; Tinhofer, I.; Budach, V.; Sak, A.; Stuschke, M.; Balermpas, P.; Rödel, C.; Schäfer, H.; Grosu, A. L.; Abdollahi, A.; Debus, J.; Ganswindt, U.; Belka, C.; Pigorsch, S.; Combs, S. E.; Mönnich, D.; Zips, D.; Baretton, G. B.; Buchholz, F.; Baumann, M.; Krause, M.; Löck, S.

This article compares the expression and applicability of biomarkers, from single genes and gene signatures, identified in patients with locally advanced head and neck squamous cell carcinoma using the GeneChip Human Transcriptome Array 2.0, nCounter, and real-time PCR analyses. Two multicenter, retrospective cohorts of patients with head and neck squamous cell carcinoma from the German Cancer Consortium Radiation Oncology Group who received postoperative radiochemotherapy or primary radiochemotherapy were considered. Real-time PCR was performed for a limited number of 38 genes of the cohort who received postoperative radiochemotherapy only. Correlations between the methods were evaluated by the Spearman rank correlation coefficient. Patients were stratified based on the expression of putative cancer stem cell markers, hypoxia-associated gene signatures, and a previously developed seven-gene signature. Locoregional tumor control was compared between these patient subgroups using log-rank tests. Gene expressions obtained from nCounter analyses were moderately correlated to GeneChip analyses (median r Z approximately 0.68). A higher correlation was obtained between nCounter analyses and real-time PCR (median r Z 0.84). Significant associations with locoregional tumor control were observed for most of the considered biomarkers evaluated by GeneChip and nCounter analyses. In general, all applied biomarkers (single genes and gene signatures) classified approximately 70% to 85% of the patients similarly. Overall, gene signatures seem to be more robust and had a better transferability among different measurement methods.

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Permalink: https://www.hzdr.de/publications/Publ-32149
Publ.-Id: 32149


The Role of lncRNAs TAPIR-1 and -2 as Diagnostic Markers and Potential Therapeutic Targets in Prostate Cancer

Friedrich, M.; Wiedemann, K.; Reiche, K.; Puppel, S. H.; Pfeifer, G.; Zipfel, I.; Binder, S.; Köhl, U.; Müller, G. A.; Engeland, K.; Aigner, A.; Füssel, S.; Fröhner, M.; Peitzsch, C.; Dubrovska, A.; Rade, M.; Christ, S.; Schreiber, S.; Hackermüller, J.; Lehmann, J.; Toma, M. I.; Muders, M. H.; Sommer, U.; Baretton, G. B.; Wirth, M.; Horn, F.

In search of new biomarkers suitable for the diagnosis and treatment of prostate cancer, genome-wide transcriptome sequencing was carried out with tissue specimens from 40 prostate cancer (PCa) and 8 benign prostate hyperplasia patients. We identified two intergenic long non-coding transcripts, located in close genomic proximity, which are highly expressed in PCa. Microarray studies on a larger cohort comprising 155 patients showed a profound diagnostic potential of these transcripts (AUC~0.94), which we designated as tumor associated prostate cancer increased lncRNA (TAPIR-1 and -2). To test their therapeutic potential, knockdown experiments with siRNA were carried out. The knockdown caused an increase in the p53/TP53 tumor suppressor protein level followed by downregulation of a large number of cell cycle- and DNA-damage repair key regulators. Furthermore, in radiation therapy resistant tumor cells, the knockdown leads to a renewed sensitization of these cells to radiation treatment. Accordingly, in a preclinical PCa xenograft model in mice, the systemic application of nanoparticles loaded with siRNA targeting TAPIR-1 significantly reduced tumor growth. These findings point to a crucial role of TAPIR-1 and -2 in PCa.

Keywords: lncRNA; prostate cancer; diagnostic marker; therapeutic target; p53; cell cycle arrest; radiation resistance

Permalink: https://www.hzdr.de/publications/Publ-32148
Publ.-Id: 32148


Men who stare at bone: multimodal monitoring of bone healing

Schulze, S.; Rothe, R.; Neuber, C.; Hauser, S.; Ullrich, M.; Pietzsch, J.; Rammelt, S.

Knowledge of the physiological and pathological processes taking place in bone during fracture healing or defect regeneration is essential in order to develop strategies to enhance bone healing under normal and critical conditions. Preclinical testing allows a wide range of imaging modalities that may be applied both simultaneously and longitudinally which will in turn lower the number of animals needed to allow a comprehensive assessment of the healing process. This work provides an up-to-date review on morphological, functional, optical, biochemical and biophysical imaging techniques including their advantages, disadvantages, and potential for combination of different modalities. The focus lies on preclinical testing of biomaterials modified with artificial extracellular matrices (aECM) in various animal models to enhance bone remodeling and regeneration.

Keywords: bone; soft tissue; remodeling; in vivo; ex vivo; matrix engineering

Permalink: https://www.hzdr.de/publications/Publ-32147
Publ.-Id: 32147


Research data: THz-driven structural phase transition in a hybrid perovskite

Deinert, J.-C.; Kovalev, S.
Project Leader: Kim, Heejae; Project Member: Jäger, Sebastian

Research data for the May 2020 beamtime on "THz-driven structural phase transition in a hybrid perovskite".

PI: Heejae Kim, MPI for polymer research, Mainz.

Keywords: Terahertz; Phase transition; Perovskite; field-driven; 2D-spectroscopy; ultrafast

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Publ.-Id: 32146


Data for: "A metabolic switch regulates the transition between growth and diapause in C. elegans"

Penkov, S.; Raghuraman, B.; Erkut, C.; Oertel, J.; Galli, R.; Ackerman, E.; Vorkel, D.; Verbavatz, J.; Koch, E.; Fahmy, K.; Shevchenko, A.; Kurzchalia, T.

calorimetry data in excel format

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Permalink: https://www.hzdr.de/publications/Publ-32145
Publ.-Id: 32145


Research data: Non-perturbative high-harmonic generation in the three-dimensional Dirac semimetal Cd₃As₂

Wang, Z.; Kovalev, S.; Deinert, J.-C.

Reserach data for Publication: Non-perturbative high-harmonic generation in the three-dimensional Dirac semimetal Cd₃As₂

DOI: 10.1038/s41467-020-16133-8

Keywords: Terahertz; high harmonics; Dirac material; carrier dynamics; ultrafast

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Permalink: https://www.hzdr.de/publications/Publ-32144
Publ.-Id: 32144


Freezing of molecular rotation in a paramagnetic crystal studied by 31P NMR

Opherden, D.; Bärtl, F.; Yamamoto, S.; Zhang, Z. T.; Luther, S.; Molatta, S.; Wosnitza, J.; Baenitz, M.; Heinmaa, I.; Stern, R.; Landee, C. P.; Kühne, H.

We present a detailed 31P nuclear magnetic resonance (NMR) study of the molecular rotation in the compound Cu(pz)2(2-HOpy) theory quantifies the related activation energies as Ea/kB = 250 and 1400 K. Further, the anisotropy of the second spectral moment of the 31P absorption line was calculated for the rigid lattice, as well as in the presence of several sets of PF6 reorientation modes, and is in excellent agreement with the experimental data. Whereas the anisotropy of the frequency shift and enhancement of nuclear spinrelaxation rates is driven by the molecular rotation with respect to the dipole fields stemming from the Cu ions, the second spectral moment is determined by the intramolecular interaction of nuclear 19F and 31P moments in the presence of the distinct rotation modes.

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Publ.-Id: 32143


Methane as a novel doping precursor for deposition of highly conductive ZnO thin films by magnetron sputtering

Vasin, A. V.; Rusavsky, A. V.; Bortchagovsky, E. G.; Gomeniuk, Y. V.; Nikolenko, A. S.; Strelchuk, V. V.; Yatskiv, R.; Tiagulskyi, S.; Prucnal, S.; Skorupa, W.; Nazarov, A. N.

ZnO thin films were deposited by RF-magnetron sputtering of ZnO powder target using pure argon and argon with methane as reactive gas. It is found that growth morphology and electronic properties of the films are strongly affected by adding of methane to argon during the deposition process. Adding of methane resulted in a high energy shift of near band edge ultraviolet photoluminescence band and quenching of deep level emission in the visible spectral range. The strongest effect of methane has been found for electrical resistivity that reduced by 3 orders of magnitude in comparison with films deposited in pure argon. Unexpectedly, the analysis of the chemical composition showed no carbon incorporated from methane. Therefore, modification effects were assigned to hydrogen incorporation. However, the direct comparison of resistivity of the films deposited using methane and molecular hydrogen as doping precursors has demonstrated that doping efficiency of the methane is about an order of magnitude larger than that of molecular hydrogen under similar deposition conditions. This advantage of the methane is discussed and assigned to specific surface chemistry of Zn–O–C–H system that enhances the formation of shallow donor defects during plasma assisted deposition process.

Keywords: ZnO; doping; photoluminescence

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Permalink: https://www.hzdr.de/publications/Publ-32142
Publ.-Id: 32142


Current Transport Mechanisms in Zinc Oxide/Silicon Carbide Heterojunction Light‐Emitting Diodes

Przezdziecka, E.; Chusnutdinow, S.; Wierzbicka, A.; Guziewicz, M.; Prucnal, S.; Stachowicz, M.; Zaleszczyk, W.; Zhou, S.; Kozanecki, A.

Herein, the properties of ZnO:N/n‐SiC heterojunctions (HJs) and light‐emitting diodes based on them are studied. The HJs are grown by molecular beam epitaxy. Active nitrogen generated by a radio frequency plasma source is used for p‐type doping. The location of the space charge area on the ZnO:N/n‐SiC interface is revealed by electron‐beam‐induced current (EBIC) scans. The diffusion lengths of holes and electrons are calculated. This article presents the characterization of ZnO:N/n‐SiC HJs and reveals the presence of tunneling‐related current transport in them as well as the contribution of exponentially distributed traps at large voltage bias. Electroluminescence (EL) is measured at ambient pressure by a standard EL system and also at 77 K in vacuum by a system utilizing EBIC in a scanning electron microscope. Analysis of the light output power at higher current level indicates the limited effect of nonradiative defects in this structure. EL results are compared with cathodoluminescence spectra. Color temperature for HJs based on the EL spectra is also calculated.

Keywords: ZnO; doping; p-n diode; electroluminescence

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Permalink: https://www.hzdr.de/publications/Publ-32141
Publ.-Id: 32141


Soft X-ray absorption study of tantalum incorporation in titanium oxide films: Impact of flash-lamp annealing

Gago, R.; Prucnal, S.; Esteban-Mendoza, D.

The impact of Ta incorporation (up to similar to 21 at.%) in titanium dioxide (TiO2) films subjected to post-deposition millisecond-range flash-lamp annealing (FLA) is addressed. Phase formation with short-range information was established by means of soft X-ray absorption near-edge structure (XANES) in combination with standard X-ray diffraction. As-grown films are X-ray amorphous, but display a significant structural improvement upon FLA. Up to relatively large Ta concentrations (similar to 12 at.%), FLA can be used to effectively incorporate Ta into a nano-crystalline anatase TiO2 phase, although its structural quality deteriorates progressively with the Ta content. For the intermediate Ta range between 12 and 17 at.%, the structure of the FLA films is highly disordered, being unable to overcome the initial distorted arrangement. In any case, rutile- or Ta2O5-like environments emerge for low and high contents, respectively. Finally, for the highest Ta content (similar to 21 at.%), the formation of good-quality nanocrystalline Ta2O5 phase occurs after FLA. As assessed by XANES, the structural evolution upon FLA seems to be determined by the initial (amorphous) structure. Lastly, all the samples are highly transparent from the visible to the near-infrared region, and the band-gap can be tailored from similar to 3.2 to similar to 3.8 eV with increasing the amount of incorporated Ta.

Keywords: Oxide materials; Doping; Sputter deposition; Flash-lamp-annealing; XANES; Band-gap engineering

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Permalink: https://www.hzdr.de/publications/Publ-32140
Publ.-Id: 32140


Kinetics of Bulk Lifetime Degradation in Float-Zone Silicon: Fast Activation and Annihilation of Grown-In Defects and the Role of Hydrogen versus Light

Hiller, D.; Markevich, V. P.; Guzman, J. A. T. D.; König, D.; Prucnal, S.; Bock, W.; Julin, J.; Peaker, A. R.; Macdonald, D.; Grant, N. E.; Murphy, J. D.

Float‐zone (FZ) silicon often has grown‐in defects that are thermally activated in a broad temperature window (≈300–800 °C). These defects cause efficient electron‐hole pair recombination, which deteriorates the bulk minority carrier lifetime and thereby possible photovoltaic conversion efficiencies. Little is known so far about these defects which are possibly Si‐vacancy/nitrogen‐related (VxNy). Herein, it is shown that the defect activation takes place on sub‐second timescales, as does the destruction of the defects at higher temperatures. Complete defect annihilation, however, is not achieved until nitrogen impurities are effused from the wafer, as confirmed by secondary ion mass spectrometry. Hydrogenation experiments reveal the temporary and only partial passivation of recombination centers. In combination with deep‐level transient spectroscopy, at least two possible defect states are revealed, only one of which interacts with H. With the help of density functional theory V1N1‐centers, which induce Si dangling bonds (DBs), are proposed as one possible defect candidate. Such DBs can be passivated by H. The associated formation energy, as well as their sensitivity to light‐induced free carriers, is consistent with the experimental results. These results are anticipated to contribute to a deeper understanding of bulk‐Si defects, which are pivotal for the mitigation of solar cell degradation processes.

Keywords: Solar cells; Si; doping; defects

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Publ.-Id: 32139


Correlations between the structural transformations and concentration quenching effect for RE-implanted ZnO systems

Ratajczak, R.; Mieszczynski, C.; Prucnal, S.; Krajewski, T. A.; Guziewicz, E.; Wozniak, W.; Kopalko, K.; Heller, R.; Akhmadaliev, S.

In this paper, we present optical, structural and electrical studies of the phenomenon called concentration quenching effect occurring in ZnO doped with Rare Earth (RE) ions. For this purpose, the epitaxial ZnO layers grown by the Atomic Layer Deposition (ALD) are doped by ion implantation with Yb and Er elements with fluencies ranging from 5 × 1013 to 1 × 1016/cm2. In order to activate optically the implanted RE and to remove defects, the post-implantation thermal annealing was performed at 800 °C for 10 min in the O2 atmosphere using a Rapid Thermal Annealing (RTA) system. Two-step processed samples, before and after annealing, were evaluated by Rutherford Backscattering Spectrometry (RBS/c) to investigate the damage build-up process in the ZnO lattice after RE ion bombardment and the lattice site location of RE. The annealed samples were examined using the photoluminescence (PL) spectroscopy and Hall effect measurements. Our studies show that the luminescence quenching effect, as well as the electrical resistivity response to the increased RE concentration, are strongly connected with the threshold of the structural transformation due to defects accumulation. It suggests that during structural transformations the RE-ion centers are sufficiently close together to be able to interact and transfer the excitation energy between each other, increasing ipso facto the probability to lose the excitation energy by non-radiative processes. Moreover, in contrast to the popular belief, that the concentration quenching effect in RE-doped ZnO depends strongly on the kind of RE-doped ion, the presented results do not provide any evidence to support such an assumption.

Keywords: Rare earth; Ytterbium; Ion Implantation; Rutherford Backscattering Spectrometry (RBS/c); Erbium

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Permalink: https://www.hzdr.de/publications/Publ-32138
Publ.-Id: 32138


Effect of roughness and nanoporosity on optical properties of black and reflective Al films prepared by magnetron sputtering

Hruška, P.; More-Chevalier, J.; Novotný, M.; Čížek, J.; Melikhova, O.; Fekete, L.; Poupon, M.; Bulíř, J.; Volfová, L.; Butterling, M.; Liedke, M. O.; Wagner, A.; Fitl, P.

In this work, a comparison of the microstructure of black and classic reflective aluminum films is provided. The N2 concentration during the magnetron sputtering deposition has a key impact on the growth process and final moth-eye-like morphology of black Al films. The study of films with thickness ~1.5 μm and ~8 μm and fully developed microstructure enabled us to clarify the origin of different optical properties of black and reflective Al. Atomic force microscopy measurements showed high roughnesses for both types of films leading to light scattering from their surface. In the case of black Al, the incident light is absorbed in a fractallike nanoporous surface. Less than 3 % of the intensity in the wavelength range from 190 nm to 1200 nm is reflected. Positronium formation in columnar nanopores with a diameter of 4 – 5 Å was observed by positron annihilation lifetime spectroscopy. The nanoporosity rather than the roughness is the key feature of black films compared to reflective ones.

Keywords: black aluminum; magnetron sputtering; atomic force microscopy; spectrophotometric reflectance; positron annihilation spectroscopy

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Pushing the doping limit for future FETs

Zhou, S.

In recent years, small-sized transistors including FinFETs or Nanowire FETs (or Gate-all-around FETs) have been manufactured to reduce the voltage and power consumption of devices. When CMOS transistors are scaled down below the 10 nm technology node, the effect of contact resistance on power consumption increases because the contact area decreases for smaller transistors. For nodes of <7 nm, the metal–semiconductor contact resistance become a dominant contributor to the total parasitic resistances of the transistor [1, 2]. To solve the problem, n- or p-type impurities were introduced at the alloy concentration in Si and SiGe [1, 2]. However, due to the self-compensation via defect complexes at high impurity concentration, the free carrier concentration saturates. In this talk, I will discuss our approaches to tackle this challenge. One is the use of deep level impurities for doping Si, for instance, chalcogen Te [3]. Contrary to general expectations, we find that with increasing Te doping concentration its interstitial fraction decreases and substitutional Te dimers become the dominant configuration. As shown by first-principle calculations, these Te dimers have the lowest formation energy and donate two electrons each to the conduction band. Another approach is to play with different annealing time scale. We find that by millisecond flash lamp annealing the dead P-dopants can be deliberated [4, 5]. Positron lifetime measurements indicate the dissolving of single vacancies. Therefore, we trace the origin of the unprecedented electron concentrations in Si and in Ge to the atomistic scale. Our results have fundamental implications in semiconductor physics as well as to the source/drain applications for future FETs.
[1] Z. Ye, et al., Applied Materials, ECS Trans. 98, 239 (2020).
[2] G. Rengo, et al., IMEC, ECS Trans. 98, 27 (2020).
[3] M. Wang, et al., Phys. Rev. Appl. 11, 054039 (2019), arXiv:1809.06055
[4] S. Prucnal, et al., Phys. Rev. Appl. 10, 064055 (2018), arXiv:1901.01721
[5] S. Prucnal, et al., New J. Phys., in press (2020).

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  • Invited lecture (Conferences)
    International Virtual School on Ion Beams in Materials Science, 01.-05.12.2020, New Delhi, India

Permalink: https://www.hzdr.de/publications/Publ-32136
Publ.-Id: 32136


Tuned AFM-FM coupling by the formation of vacancy complex in Gd0.6Ca0.4MnO3 thin film lattice

Beiranvand, A.; Liedke, M. O.; Haalisto, C.; Lähteenlahti, V.; Schulman, A.; Granroth, S.; Palonen, H.; Butterling, M.; Wagner, A.; Huhtinen, H.; Paturi, P.

The effect of in situ oxygen and vacuum annealings on the low bandwidth manganite Gd1-xCaxMnO3 (GCMO) thin film with x = 0:4 was investigated. Based on the magnetic measurements, the AFM-FM coupling is suppressed by the vacuum annealing treatment via destroying the double exchange interaction and increasing the unit cell volume by converting the Mn4+ to the Mn3+. Consequently, resistance increases significantly compared to pristine film. The results are explained by a model obtained from the positron annihilation studies, where the vacuum annealing increased the annihilation lifetime in A and B sites due to the formation of vacancy complexes VA;B - VO, which was not the case in the pristine sample. The positron annihilation analysis indicated that most of the open volume defects have been detected in the interface region rather than on the subsurface layer and this result is confirmed by detailed x-ray reflection analysis. On the other hand, the effect of oxygen annealing on the unit cell volume and magnetization was insignificant. This is in agreement with positron annihilation results which demonstrated that the introduction of oxygen does not change the number of cation vacancies significantly. This work demonstrates that the modification of oxygen vacancies and vacancy complexes can tune magnetic and electronic structure of the epitaxial thin films to provide new functionalities in future applications.

Keywords: positron annihilation spectroscopy; positron annihilation lifetime spectroscopy; Doppler broadening; defetcs; Gd; annealing; Ca; MnO3

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T Cell Mediated Conversion of a Non-anti-La Reactive B cell to an Autoreactive anti-La B Cell by Somatic Hypermutation

Bachmann, M.; Bartsch, T.; Bippes, C. C.; Bachmann, D.; Puentes-Cala, E.; Bachmann, J.; Bartsch, H.; Arndt, C.; Koristka, S.; Rodrigues Loureiro, L. R.; Kegler, A.; Laube, M.; Gross, J. K.; Gross, T.; Kurien, B.; Scofield, R. H.; Farris, A. D.; James, J. A.; Schmitz, M.; Feldmann, A.

Since the first description of the nuclear autoantigens in the late sixties and early seventies of the last century we and many other groups have tried with difficulty to establish monoclonal anti-bodies (mabs) against nuclear antigens including to the autoantigen La/SS-B. To date, only a few anti-La mabs have been derived by conventional hybridoma technology. However, these pre-viously described anti-La mabs are not bona fide autoantibodies as they recognize either human La specific- or cryptic or post-translationally modified epitopes which are not accessible on na-tive mouse La protein. Herein we present a series of novel murine anti-La mabs including truly autoreactive ones. These mabs were elicited from a human La transgenic animal through adop-tive transfer of T cells from non-transgenic mice immunized with human La antigen. Detailed epitope and paratope analyses experimentally confirm the hypothesis that somatic hypermuta-tions occurring during T cell dependent maturation can lead to autoreactivity to the nuclear au-toantigen La/SS-B.

Keywords: anti-La/SS-B antibodies; autoimmunity; La/SS-B autoantigen; Systemic Lupus Erythematosus; primary Sjögren’s Syndrome

Permalink: https://www.hzdr.de/publications/Publ-32134
Publ.-Id: 32134


Ansible GitLab Base Role

Hüser, C.; Ziegner, N.; Huste, T.

This Ansible Role provides a basic setup for services based on GitLab Omnibus.

Keywords: gitlab; ansible

  • Software in external data repository
    Publication year 2020
    Programming language: Ansible
    System requirements: Centos, Ubuntu
    License: Apache-2.0 (Link to license text)
    Hosted on GitLab.com: Link to location

Permalink: https://www.hzdr.de/publications/Publ-32133
Publ.-Id: 32133


Ansible Role Redis

Hüser, C.; Ziegner, N.; Huste, T.

An Ansible role to set up multiple Redis instances to be used as caching servers in a High Availability and Scalability context.

Keywords: redis; ansible; cache; high availability

  • Software in external data repository
    Publication year 2020
    Programming language: Ansible
    System requirements: Ubuntu
    License: Apache-2.0 (Link to license text)
    Hosted on GitLab.com: Link to location

Permalink: https://www.hzdr.de/publications/Publ-32132
Publ.-Id: 32132


Ansible Role HAProxy

Hüser, C.; Ziegner, N.; Huste, T.

An Ansible role to set up HAProxy to be used as a load balancer in a high availability and scalability context.

Keywords: haproxy; loadbalancer; networking; web; ansible

  • Software in external data repository
    Publication year 2020
    Programming language: Ansible
    System requirements: Ubuntu
    License: Apache-2.0 (Link to license text)
    Hosted on GitLab.com: Link to location

Permalink: https://www.hzdr.de/publications/Publ-32131
Publ.-Id: 32131


Ansible Role GitLab

Hüser, C.; Huste, T.; Ziegner, N.

Ansible role to configure GitLab Omnibus installation.

Keywords: gitlab; ansible

  • Software in external data repository
    Publication year 2020
    Programming language: Ansible
    System requirements: Ubuntu
    License: Apache-2.0 (Link to license text)
    Hosted on GitLab.com: Link to location

Permalink: https://www.hzdr.de/publications/Publ-32130
Publ.-Id: 32130


Sub-20 nm multilayer nanopillar patterning for hybrid SET/CMOS integration

Pourteau, M.-L.; Gharbi, A.; Brianceau, P.; Dallery, J.-A.; Laulagnet, F.; Rademaker, G.; Tiron, R.; Engelmann, H.-J.; Borany, J.; Heinig, K.-H.; Rommel, M.; Baier, L.

SETs (Single-Electron-Transistors) arouse growing interest for their very low energy consumption. For future industrialization, it is crucial to show a CMOS-compatible fabrication of SETs, and a key prerequisite is the patterning of sub-20 nm Si Nano-Pillars (NP) with an embedded thin SiO2 layer. In this work, we report the patterning of such multi-layer isolated NP with e-beam lithography combined with a Reactive Ion Etching (RIE) process. The Critical Dimension (CD) uniformity and the robustness of the Process of Reference are evaluated.
Characterization methods, either by CD-SEM for the CD, or by TEM cross-section for the NP profile, are compared and discussed.

Keywords: Single-electron transistor; Multilayer nanopillars; Silicon nanodots; E-beam lithography; Reactive ion etching; Energy-filtered transmission electron microscopy

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Permalink: https://www.hzdr.de/publications/Publ-32129
Publ.-Id: 32129


ESUO - The European Synchrotron and FEL User Organisation: Aims and activities

Aksoy, A.; Arčon, I.; Arikan, P.; Bittencourt, C.; Boscherini, F.; Braz Fernandes, F. M.; Brooks, N.; Casu, B.; Cianci, M.; Feiters, M.; Froideval, A.; Granroth, S.; Gross, S.; Gutt, C.; Hase, T.; Jablonska, K.; Jergel, M.; Karsli, Ö.; Khan, A.; Kirm, M.; Kokkinidis, M.; Kövér, L.; Kuzmin, A.; Landau, M.; Larsen, H. B.; Lechner, R. T.; Le-Hir, R.; Logan, D. T.; López, O.; Lorentz, K.; Mariani, C.; Marinkovic, B.; McGuinness, C.; Meedom Nielsen, M.; Mičetić, M.; Mikulík, P.; Padežnik Gomilšek, J.; Petukhov, A.; Pietsch, U.; Renault, L.; Russell, A.; Shivachev, B.; Sobierajski, R.; Stangl, J.; Thissen, R.; Tromp, M.; Vankó, G.; Witkowska, A.; Blasetti, C.; Freire Anselmo, A. S.; Grobosch, M.; Helm, M.; Schramm, B.; Schultheiss, K.; Vollmer, A.

The European Synchrotron and free-electron laser User Organisation (ESUO) represents about 22.000 users from 30 European member states and associated countries. Each country is represented within ESUO by one up to four national delegate(s), depending on the size of the user community in the respective country. The ESUO aims and activities are shown in this poster.

  • Poster (Online presentation)
    12th BESSY@HZB USER MEETING, 10.12.2020, Berlin-Adlershof, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-32128
Publ.-Id: 32128


Proposal for the delineation of neoadjuvant target volumes in oesophageal cancer

Thomas, M.; Mortensen, H.; Hoffmann, L.; Møller, D.; Troost, E. G. C.; Muijs, C.; Berbee, M.; Bütof, R.; Nicholas, O.; Radhakrishna, G.; Defraene, G.; Nafteux, P.; Nordsmark, M.; Haustermans, K.

Purpose
To define instructions for delineation of target volumes in the neoadjuvant setting in oesophageal cancer.
Materials and methods
Radiation oncologists of five European centres participated in the following consensus process: [1] revision of published (MEDLINE) and national/institutional delineation guidelines; [2] first delineation round of five cases (patient 1–5) according to national/institutional guidelines; [3] consensus meeting to discuss the results of step 1 and 2, followed by a target volume delineation proposal; [4] circulation of proposed instructions for target volume delineation and atlas for feedback; [5] second delineation round of five new cases (patient 6–10) to peer review and validate (two additional centres) the agreed delineation guidelines and atlas; [6] final consensus on the delineation guidelines depicted in an atlas.
Target volumes of the delineation rounds were compared between centres by Dice similarity coefficient (DSC) and maximum/mean undirected Hausdorff distances (Hmax/Hmean).
Results
In the first delineation round, the consistency between centres was moderate (CTVtotal: DSC = 0.59–0.88; Hmean = 0.2–0.4 cm). Delineations in the second round were much more consistent. Lowest variability was obtained between centres participating in the consensus meeting (CTVtotal: DSC: p < 0.050 between rounds for patients 6/7/8/10; Hmean: p < 0.050 for patients 7/8/10), compared to validation centres (CTVtotal: DSC: p < 0.050 between validation and consensus meeting centres for patients 6/7/8; Hmean: p < 0.050 for patients 7/10).
A proposal for delineation of target volumes and an atlas were generated.
Conclusion
We proposed instructions for target volume delineation and an atlas for the neoadjuvant radiation treatment in oesophageal cancer. These will enable a more uniform delineation of patients in clinical practice and clinical trials.

Keywords: Oesophageal cancer; Neoadjuvant chemoradiation; Proposal for delineation; Delineation atlas; Consensus

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Solvent extraction of boric acid: comparison of five different monohydric alcohols and equilibrium modeling with numerical methods

Balinski, A.; Recksiek, V.; Kelly, N.

Solvent extraction is one of the common methods for the recovery of boric acid (or boron) from aqueous solutions. A wide variety of different compounds including monohydric alcohols has been tested and there is a wide recognition that they are rather ineffective compared to other extractants such as diols. Nevertheless, monohydric alcohols find application in industrial processes demonstrating their efficiency. The intention of this study is to clarify this discrepancy and to provide an overall picture of monohydric alcohols as an extractant for boric acid. Five different monohydric alcohols are the object of this study: n-octanol, 2-ethyl-1-hexanol, 2-butyl-1-octanol, 2-octanol and 3,7-dimethyl-3-octanol. A special focus is to examine the effect of the structure of carbon chain and the effect of the composition of aqueous phase on the extraction efficiency. Despite the extraction efficiency for boric acid other important properties are examined such as the viscosity of organic phase, the solubility of alcohols in aqueous phase and the co-extraction of salts used as a salting-out agent (NaCl, Na₂SO₄, MgCl₂, LiCl, LiNO₃). Finally, the relationship between the number of theoretical stages and the phase ratio at equilibrium for selected extraction systems is evaluated with MATLAB.

Keywords: boron; boric acid; solvent extraction; separation; monohydric alcohols; n-octanol; 2-ethyl-1-hexanol; 2-butyl-1-octanol; 2-octanol; 3,7-dimethyl-3-octanol

Permalink: https://www.hzdr.de/publications/Publ-32126
Publ.-Id: 32126


Integrated Environmental Monitoring of AMD Affected Waters using Hyperspectral Imaging and In-situ Analytics

Flores Rojas, H. M.; Lorenz, S.; Jackisch, R.; Tusa, L.; Contreras Acosta, I. C.; Gloaguen, R.

One of the potential major consequences of mining activities is the degradation of the surrounding ecosystems by Acid Mine Drainage (AMD). A high-resolution hyperspectral drone-borne survey provides a useful, fast, and non-invasive tool to monitor the acid mine drainage mineralogy in mining sites. In this study, we propose to integrate drone-borne visible-to-near infrared (VNIR) hyperspectral data and physicochemical field data from water and sediments together with laboratory analysis for precise mineralogical and surface water mapping. The Tintillo River is an extraordinary case of the collection of acidic leachates in southwest Spain. This river is highly contaminated, with large quantities of dissolved metals (Fe, Al, Cu, Zn, etc.) and acidity, which later discharged into the Odiel River. At the confluence of the Tintillo and Odiel rivers, different geochemical and mineralogical processes typical of the interaction of very acidic water (pH 2.5 - 3.0) with circum-neutral water (pH 7.0 - 8.0) occur. The high contrast among waters makes this area propitious for the use of hyperspectral data to characterize both rivers and better evaluate mine water bodies with remote sensing imagery. We present an approach that makes use of a supervised random forest regression for the extended mapping of water properties, using the data from collected field samples, as training set for the algorithm. Experimental results show water surface maps that quantify the concentration of dissolved metals and physical-chemical properties along the covered region and mineral classification maps distribution (jarosite, goethite, schwertmannite, etc.). These results highlight the capabilities of drone-borne hyperspectral data for monitoring mining sites by extrapolating the hydrochemical properties from certain and specific areas, covered during field campaigns, to larger regions where accessibility is limited. By following this method, it is possible to rapidly discriminate and map the degree of AMD contamination in water for its future treatment or remediation.

Keywords: hyperspectral; remote sensing; machine learning; unmanned aerial system; acid mine drainage

Permalink: https://www.hzdr.de/publications/Publ-32125
Publ.-Id: 32125


Slice2Volume: Fusion of multimodal medical imaging and light microscopy data of irradiation-injured brain tissue in 3D.

Müller, J.; Suckert, T.; Beyreuther, E.; Schneider, M.; Boucsein, M.; Bodenstein, E.; Stolz-Kieslich, L.; Krause, M.; Neubeck, C. V.; Haase, R.; Lühr, A.; Dietrich, A.; Nexhipi, S.

The dataset contains comprehensive image data for a total of nine mice, which underwent normal tissue brain irradiation with 90 MeV protons.             
In particular, the image data comprise cone-bem computed tomographies (CBCT), Monte Carlo beam transport simulations based on those CTs, regular magnetic resonance imaging (MRI) follow-up (≥ 26 weeks), a co-aligned DSURQE mouse brain atlas and scanned whole-brain tissue sections with histochemical and immunofluorescent markers for morphology (H&E), cell nuclei (DAPI), astrocytes (GFAP), microglia (Iba1), the intermediate filament protein Nestin, proliferation (Ki67), neurons (NeuN) and oligodendrocytes (OSP).          
The volumetric image data (i.e. CBCT, MRI and brain atlas) were co-aligned using the ImageJ plugin Big Warp. The CBCT data was used as spatial reference to allow for mask-based, slice-wise alignment of CBCT and light microscopy image data in 3D with the scriptable registration tool Elastix.  

We provide the data in raw format and as aligned data sets, as well as their spatial transformations.

Keywords: Preclinical; Image fusion; Proton radiation; Medical imaging; Histology

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Publ.-Id: 32124


On Curie Temperature of MnSi films

Li, Z.; Yuan, Y.; Begeza, V.; Rebohle, L.; Helm, M.; Nielsch, K.; Prucnal, S.; Zhou, S.

B20-type MnSi is the prototype magnetic skyrmion material. Thin films of MnSi have a higher Curie temperature than its bulk counterpart. It is not yet clear by what and how the Curie temperature of MnSi thin films is affected. In this work, we grow MnSi films on Si(100) and Si(111) substrates with a broad variation in their structures. By controlling the Mn thickness and annealing parameters, the pure MnSi phase of polycrystalline and textured nature as well as the mixed phase of MnSi and MnSi1.7 are obtained. Surprisingly, all these MnSi films show an increased Curie temperature of up to around 43 K. However, the Curie temperature is independent of the structural parameters within our accessibility including the film thickness above a threshold, strain, cell volume and the mixture with MnSi1.7. Our work is drawing to revisit the origin of the Curie temperature of MnSi films.

Keywords: B20 MnSi; Curie temperature; Strain; Defects

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  • Open Access Logo Scientific Reports 12(2022), 16388

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Publ.-Id: 32123


B20-type FeGe on Ge(100) prepared by pulsed laser melting

Li, Z.; Xie, Y.; Yuan, Y.; Wang, M.; Xu, C.; Hübner, R.; Prucnal, S.; Zhou, S.

B20-type FeGe is one of the noncentrosymmetric materials hosting magnetic skymions. In this work, we have prepared B20-type FeGe films by pulsed laser melting of metal Fe deposited on Ge(100). The formation of the B20 phase is confirmed by X-ray diffraction. The FeGe samples show a superparamagnetic behaviour and their blocking temperatures increase with increasing the pulsed laser energy density. We conclude that this phenomenon is due to the increased grain size of the B20-type FeGe with increasing laser energy density. The presented method can be used to obtain different B20-type transition metal germanides and silicides, which can be magnetic skyrmion-hosting materials for spintronics.

Keywords: B20 phase; FeGe; Pulsed laser melting; Superparamagnetism

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Permalink: https://www.hzdr.de/publications/Publ-32122
Publ.-Id: 32122


Teaching ML in Compact Courses

Fouilloux, A.; Steinbach, P.

This talk summarizes the experiences made with teaching Machine Learning within compact events that stretch over several days to a week maximum. Both speakers explain pitfalls they were caught in as well as solutions they found.

This talk was given at the Teaching Machine Learning workshop at ECML-PKDD 2020. For more details and information see https://teaching-ml.github.io/2020/

Keywords: teaching; compact courses; machine learning; artificial intelligence

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Publ.-Id: 32121


Teaching ML in Compact Courses

Fouilloux, A.; Steinbach, P.

This talk summarizes the experiences made with teaching Machine Learning within compact events that stretch over several days to a week maximum. Both speakers explain pitfalls they were caught in as well as solutions they found.

Keywords: Machine Learning; Teaching; Artificial Intelligence; Bootcamp; courses

  • Open Access Logo Lecture (Conference) (Online presentation)
    European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases, 14.-18.09.2020, virtual, virtual
    DOI: 10.14278/rodare.753

Permalink: https://www.hzdr.de/publications/Publ-32120
Publ.-Id: 32120


Study of effective parameters on generating submicron (nano)-bubbles using the hydrodynamic cavitation

Hassanzadeh, A. C.; Nazari, S. A.; Shafaei, S. Z. A.; Azizi, A. D.; Gharabaghi, M. A.; Ahmadi, R. E.; Shahbazi, B. F.

Although submicron (nano)-bubbles (NBs) have been broadly used in the laboratory flotation processes, the role of critical factors in their generation is not adequately explored in the literature. The present study investigates the effect of six key factors on generating submicron-sized bubbles and its application to coarse-sized quartz flotation. Interaction of influential factors is highlighted, which was generally overlooked in previous studies. These parameters i.e. frother type (MIBC and A65), frother dosage (50-130 mg/L), air flow rate (0.1-0.4 L/min), pressure in Venturi tube (250-400 kPa), liquid temperature (22-42 °C) and pH (6-10) were evaluated through software based statistical fractional factorial design. The size distribution of NBs produced by the principle of hydrodynamic cavitation was measured using a laser particle size analyzer (LPSA), and Sauter mean bubble diameter (d32) was considered as the experimental design response. Batch flotation experiments were performed with and without the A65 and MIBC-NBs. The results of experimental design showed that relative intensity of the main factors followed the order of air flow rate>temperature>frother type as the most effective parameters on the bubble size. It was revealed that the lowest air flow rate (0.1 L/min) produced the smallest bubbles. Meanwhile, the d32 decreased as the liquid temperature increased, and the bubble size strongly was related to the frother type and its concentration. Indeed, with changing frother from MIBC to A65, the reduction in mean bubble size was two-fold. Interaction of frother type with its dosage, air flow rate and pressure were statistically recognized significant on the mean bubble size, which was confirmed by p-values. Finally, flotation recovery of quartz particles improved ca. 22% in the presence of NBs compared to the conventional flotation. © Wroclaw University of Science and Technology.

Keywords: Bulk nanobubbles (NBs); Frother typeTemperatur; Fractional factorial design; Coarse quartz particles

Permalink: https://www.hzdr.de/publications/Publ-32119
Publ.-Id: 32119


Multi-octave high-dynamic range optical spectrometer for single-pulse, longitudinal characterization of ultrashort electron bunches

Zarini, O.; Couperus Cabadağ, J. P.; Chang, Y.-Y.; Köhler, A.; Kurz, T.; Schöbel, S.; Seidel, W.; Bussmann, M.; Schramm, U.; Irman, A.; Debus, A.

We present design and realization of an ultra-broadband optical spectrometer capable of measuring the spectral intensity of multi-octave-spanning light sources on a single-pulse basis with a dynamic range of up to 8 orders of magnitude. The instrument is optimized for the characterization of the temporal structure of femtosecond long electron bunches by analyzing the emitted coherent transition radiation (CTR) spectra. The spectrometer operates within the spectral range of 250nm to 11.35µm, corresponding to 5.5 optical octaves. This is achieved by dividing the signal beam into three spectral groups, each analyzed
by a dedicated spectrometer and detector unit. The complete instrument was characterized with regard to wavelength, relative spectral sensitivity, and absolute photo-metric sensitivity, always accounting for the light polarization and comparing different calibration methods. Finally, the capability of the spectrometer is demonstrated with a CTR measurement of a laser wakefield accelerated electron bunch, enabling to determine temporal pulse structures at unprecedented resolution.

Keywords: Single-shot; broadband spectrometer; absolute calibration; coherent transition radiation; laser wakefield acceleration; CTR; electron bunch length

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Permalink: https://www.hzdr.de/publications/Publ-32118
Publ.-Id: 32118


Phase selection in Mn-Si alloys by fast solid-state reaction with enhanced skyrmion stability

Li, Z.; Xie, Y.; Yuan, Y.; Ji, Y.; Begeza, V.; Cao, L.; Hübner, R.; Rebohle, L.; Helm, M.; Kornelius, N.; Prucnal, S.; Zhou, S.

B20-type transition-metal silicides or germanides are noncentrosymmetric materials hosting magnetic skyrmions, which are promising information carriers in spintronic devices. The prerequisite is the preparation of thin films on technology-relevant substrates with magnetic skyrmions stabilized at a broad temperature and magnetic-field working window. The canonical example is the B20-MnSi film grown on Si substrates. However, the as-yet unavoidable contamination with MnSi1.7 occurs due to the lower nucleation temperature of this phase. In this work, we report a simple and efficient method to overcome this problem and prepare single-phase MnSi films on Si substrates. It is based on the millisecond reaction between metallic Mn and Si using flash lamp annealing (FLA). By controlling the FLA energy density, we can grow single-phase MnSi or MnSi1.7 or their mixture at will. Compared with bulk MnSi the prepared MnSi films show an increased Curie temperature of up to 41 K. In particular, the magnetic skyrmions are stable over a much wider temperature and magnetic-field range than reported previously. Our results constitute a novel phase selection approach for alloys and can help enhance specific functional properties such as enhancing the stability of magnetic skyrmions.

Keywords: B20-MnSi; Flash lamp annealing; Phase separation; Skyrmions

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Permalink: https://www.hzdr.de/publications/Publ-32117
Publ.-Id: 32117


Towards a first Joule-level activation of PEnELOPE

Löser, M.; Siebold, M.; Schramm, U.

We present a status update of the PEnELOPE laser system currently under construction at the Helmholtz-Zentrum Dresden-Rossendorf in order to perform a first activation with pulses on the Joule scale, as well as improvements of the stretcher optics to support laser pulses in the order of 150 fs

Keywords: laser; diode pumped; ytterbium; CPA

  • Lecture (Conference) (Online presentation)
    10th Advanced Lasers and Photon Sources Conference (ALPS2021), 19.-22.04.2021, Yokohama, Japan

Permalink: https://www.hzdr.de/publications/Publ-32116
Publ.-Id: 32116


Non-reciprocal spin wave propagation in magnetic bilayer structures

Gladii, O.; Salikhov, R.; Gallardo, R. A.; Hellwig, O.; Lindner, J.; Schultheiß, H.

One of the peculiar features of waves in general is their option of non-reciprocal dispersion relation, meaning the modification of the transport characteristics upon reversal of the waves’ propagation direction. Non-reciprocity in case of Magnetostatic Surface Spin Waves (MSSW) can be caused by various factors, such as surface anisotropy [1], interfacial Dzyaloshinskii-Moriya interaction [2] or inhomogeneous saturation magnetization across the film thickness [3]. Recently, it has been shown that a strong non-reciprocal propagation can be induced by the dynamic dipole-dipole interaction between two magnetic layers in spin-valve-like structures, for which the relative magnetization orientation in remanence is stabilized in antiparallel configuration [4]. In the present work we investigate the frequency non-reciprocity in ferromagnetic bilayer systems, where a nonmagnetic thin Ru interlayer is used to achieve antiferromagnetic alignment at zero field. Using conventional Brillouin light scattering, we perform systematic measurements of the frequency non-reciprocity as a function of an external magnetic field. As expected [4], for antiparallel alignment of the magnetic moments in the two layers we observe a large frequency non-reciprocity up to a few GHz, which vanishes when the relative magnetization orientation switches to the parallel configuration. Moreover, a non-monotonous dependence of the frequency non-reciprocity is found in the transition from the antiparallel to the parallel orientation, where the maximum of the frequency shift corresponds to the spin-flop phase. By varying the parameters of the bilayer structures, the non-reciprocal propagation at the spin-flop transition is studied. We demonstrate that by adjusting the strength of the exchange coupling between the two ferromagnetic layers via the appropriate choice of the stack parameters, one can precisely control the non-reciprocal propagation of spin waves via the field-driven magnetization reorientation.

Keywords: spin wave; Brillouin light scattering; non-reciprocity; magnetic bilayers

  • Poster (Online presentation)
    MMM 2020 Virtual Conference, 02.-06.11.2020, Virtual event, Virtual event

Permalink: https://www.hzdr.de/publications/Publ-32115
Publ.-Id: 32115


The state of platinum in pyrrhotite determined by X-ray absorption spectroscopy

Filimonova, O. N.; Trigub, A. L.; Nickolsky, M. S.; Chareev, D. A.; Kvashnina, K.; Kovalchuk, E. V.; Vikentyev, I. V.; Reukov, V. L.; Tagirov, B.

Pyrrhotite Fe 1-x S is the main component of platinum group elements (PGE) ores and contains from few tenths of ppm to a few hundred ppm of disseminated Pt. Here we report an investigation of the state of Pt in synthetic pyrrhotite performed by X-ray absorption spectroscopy (XAS) in combination with theoretical spectra modeling. The pyrrhotite crystals were obtained by means of salt flux technique, using an eutectic mixture of alkali metal halides as a transport media. Analysis of the chemical composition of synthesized crystals showed that an increase of the temperature and sulfur fugacity yields higher concentrations of Pt in pyrrhotite. The Pt content reaches 0.6 wt% at the maximum studied temperature and sulfur fugacity ( t = 720°C, log f (S 2 ) = -0.1) in Pt-saturated system. Analysis of Pt L 3 -edge XANES spectra revealed that Pt presents in pyrrhotite in the 4+ and 2+ “formal” oxidation states. Theoretical modeling of XANES and approximation of EXAFS spectra showed that Pt 4+ substitutes for Fe in the crystal lattice of pyrrhotite, whereas Pt 2+ forms PtS-like clusters disseminated in the pyrrhotite matrix. Atoms of isomorphous Pt are surrounded by 6 S atoms at a distance of 2.39±0.02 Å. According to theoretical FDMNES simulations of XANES spectra, in the solid solution state the 2 nd coordination sphere of Pt contains one vacancy in the Fe sublattice within the Fe-layer. The PtS-like clusters can be considered as a quench product. High sulfur fugacity stabilizes the solid solution Pt and prevents the formation of the PtS-like clusters during cooling.

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Permalink: https://www.hzdr.de/publications/Publ-32114
Publ.-Id: 32114


Impact of Surface Reactivity on the Simulation of Mineral Dissolution Rates

Schabernack, J.; Fischer, C.

The kinetics of mineral dissolution plays a key role in many environmental and technical fields, e.g., weathering, building materials, as well as host rock characterization for potential nuclear waste repositories. Mineral dissolution rates are controlled by two parameters: (1) transport of dissolved species over and from the interface determined by advective fluid flow and diffusion (transport control) and (2) availability and distribution of reactive sites on the crystal surface (surface reactivity control). Reactive transport models (RTM) simulating species transport commonly calculate mineral dissolution by using rate laws [1]. However, the applied rate laws solely depend on species concentration in the fluid. While the effect of transport-controlled processes is addressed in current RTM approaches, the intrinsic variability of surface reactivity is neglected. Experimental studies under surface-controlled dissolution conditions have shown that surface reactivity is heterogeneously distributed over the surface [e.g., 2]. This heterogeneity in reactivity is largely caused by nanotopographical structures on the crystal surface, such as steps and etch pits. These structures are generated through defects in the crystal lattice. At these structures, the high density of reactive kink sites is leading to a local increase in surface reactivity observable through high dissolution rates.
In this study, we test whether the current rate calculation approach applied in RTMs is sufficient to reproduce experimentally observed rate heterogeneities. We apply a standard RTM approach combined with the measured surface topography of a calcite single crystal [2]. Calcite is an important mineral component in the sandy facies of the Opalinus clay formation, that is under investigation for nuclear waste storage. The modeled surface dissolution rate maps are compared to experimentally derived rate maps. Results show that the current RTM is not able to reproduce the measured rate heterogeneities on the calcite surface. To improve the predictive capabilities of RTMs over the large time scales required for the safety assessment of nuclear waste repositories, the surface reactivity that is intrinsic to the mineral needs to be implemented into future rate calculations. Investigating calcite surface reactivity in the context of dissolution can also yield information about other kinetic surface processes such as the adsorption of radionuclides during transport. We show the integration of surface reactivity into rate calculation by using a proxy parameter. The slope of the crystal surface at the nm scale is applied. We show that by adding a factor based on the slope to the rate law the RTM is able to approximate experimental rate maps. Other proxy parameters such as surface roughness could yield similar results as well. The implementation of surface reactivity proxy parameters will allow for a more precise prediction of host rock-fluid interaction over large time scales in RTMs, relevant for safety assessment of nuclear waste repositories.

[1] Agrawal, P., Raoof, A., Iliev, O. and Wolthers, M. (2020): Evolution of pore-shape and its impact on pore conductivity during CO2 injection in calcite: Single pore simulations and microfluidic experiments. Advances in Water Resources, 136, 103480.
[2] Bibi, I., Arvidson, R.S., Fischer, C. and Lüttge, A. (2018): Temporal Evolution of Calcite Surface Dissolution Kinetics. Minerals, 8, 256.

Keywords: Reactive Transport Model; Mineral Dissolution; Crystal Surface Reactivity

  • Lecture (Conference) (Online presentation)
    EGU General Assembly 2021 vEGU21: Gather Online, 19.-30.04.2021, Online, Online
    DOI: 10.5194/egusphere-egu21-11079

Permalink: https://www.hzdr.de/publications/Publ-32113
Publ.-Id: 32113


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