Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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

35810 Publications

DFT Surrogate modeling with the Materials Learning Algorithms (MALA) – Theoretical Background

Fiedler, L.

MALA (Materials Learning Algorithms) is a data-driven framework to generate surrogate models of density functional theory calculations based on machine learning. Its purpose is to enable multiscale modeling by bypassing computationally expensive steps in state-of-the-art density functional simulations. In this talk, an overview over the theoretical background that enables estimation of physical quantities based on the local density of states (LDOS) is given.

Keywords: Density Functional Theory; Machine Learning

  • Open Access Logo Lecture (Conference) (Online presentation)
    (TD)DFT Student Seminar Series (#5), 03.08.2021, Newark, USA

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Permalink: https://www.hzdr.de/publications/Publ-33063
Publ.-Id: 33063


Scale-dependent anisotropy, energy transfer and intermittency in bubble-laden turbulent flows

Ma, T.; Ott, B.; Fröhlich, J.; Bragg, A.

Data from Direct Numerical Simulations of disperse bubbly flows in a vertical channel are used
to study the effect of the bubbles on the carrier-phase turbulence. We developed a new method,
based on an extension of the barycentric map approach, that allows to quantify and visualize the
anisotropy and componentiality of the flow at any scale. Using this we found that the bubbles
significantly enhance anisotropy in the flow at all scales compared with the unladen case, and
that for some bubble cases, very strong anisotropy persists down to the smallest scales of the
flow. The strongest anisotropy observed was for the cases involving small bubbles. Concerning
the energy transfer among the scales of the flow, our results indicate that for the bubble-laden
cases, the energy transfer is from large to small scales, just as for the unladen case. However,
there is evidence of an upscale transfer when considering the transfer of energy associated with
particular components of the velocity field. Although the direction of the energy transfer is the
same with and without the bubbles, the behaviour of the energy transfer is significantly modified
by the bubbles, suggesting that the bubbles play a strong role in altering the activity of the
nonlinear term in the flow. The skewness of the velocity increments also reveal a strong effect of
the bubbles on the flow, changing both its sign and magnitude compared with the single-phase
case. We also consider the normalized forms of the fourth-order structure functions, and the
results reveal that the introduction of bubbles into the flow strongly enhances intermittency in the
dissipation range, but suppresses it at larger scales. This strong enhancement of the dissipation
scale intermittency has significant implications for understanding how the bubbles might modify
the mixing properties of turbulent flows.

Keywords: turbulence; bubbly flows

Permalink: https://www.hzdr.de/publications/Publ-33057
Publ.-Id: 33057


Implementing Heterogeneous Crystal Surface Reactivity in Reactive Transport Simulations: The Example of Calcite Dissolution

Karimzadeh, L.; Fischer, C.

Both surface reactivity and fluid dynamics control the dissolution kinetics of crystalline material. In this study, we performed a 3D reactive transport simulation to investigate the impact of surface topography heterogeneity superimposed to fluid transport heterogeneity on the dissolution rate of calcite. The
model simulates the chemical reaction of calcite dissolution, solute transport, and crystal surface geometry evolution. Importantly, we introduce heterogeneous surface reactivity into the reactive transport simulation. We test the surface slope factor as a proxy value for the intrinsic surface reactivity of dissolving crystal surface nanotopographies. Experimental data sets collected using vertical scanning interferometry validate this approach. The novel parametrization allows for the simulation of surface-controlled heterogeneous reactivity in reactive transport simulations of mineral surface dissolution.

Keywords: reactive transport modeling; crystal surface reactivity; rate map; dissolution rate variability; calcite dissolution

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  • Secondary publication expected from 26.08.2022

Permalink: https://www.hzdr.de/publications/Publ-33053
Publ.-Id: 33053


Multiscale modelling for fusion and fission materials: the M4F project

Malerba, L.; Caturla, M. J.; Gaganidze, E.; Kaden, C.; Konstantinović, M. J.; Olsson, P.; Robertson, C.; Rodney, D.; Ruiz-Moreno, A. M.; Serrano, M.; Aktaa, J.; Anento, N.; Austin, S.; Bakaev, A.; Balbuena, J. P.; Bergner, F.; Boioli, F.; Boleininger, M.; Bonny, G.; Castin, N.; Chapman, J. B. J.; Chekhonin, P.; Clozel, M.; Devincre, B.; Dupuy, L.; Diego, G.; Dudarev, S. L.; Fu, C. C.; Gatti, R.; Gélébart, L.; Gómez-Ferrer, B.; Gonçalves, D.; Guerrero, C.; Gueye, P. M.; Hähner, P.; Hannula, S. P.; Hayat, Q.; Hernández-Mayoral, M.; Jagielski, J.; Jennett, N.; Jiménez, F.; Kapoor, G.; Kraych, A.; Khvan, T.; Kurpaska, L.; Kuronen, A.; Kvashin, N.; Libera, O.; Ma, P. W.; Manninen, T.; Marinica, M. C.; Merino, S.; Meslin, E.; Mompiou, F.; Mota, F.; Namburi, H.; Ortiz, C. J.; Pareige, C.; Prester, M.; Rajakrishnan, R. R.; Sauzay, M.; Serra, A.; Simonovski, I.; Soisson, F.; Spätig, P.; Tanguy, D.; Terentyev, D.; Trebala, M.; Trochet, M.; Ulbricht, A.; Vallet, M.; Vogel, K.; Yalcinkaya, T.; Zhao, J.

The M4F project brings together the fusion and fission materials communities working on the prediction of radiation damage production and evolution and its effects on the mechanical behaviour of irradiated ferritic/martensitic (F/M) steels. It is a multidisciplinary project in which several different experimental and computational materials science tools are integrated to understand and model the complex phenomena associated with the formation and evolution of irradiation induced defects and their effects on the macroscopic behaviour of the target materials. In particular the project focuses on two specific aspects: (1) To develop physical understanding and predictive models of the origin and consequences of localised deformation under irradiation in F/M steels; (2) To develop good practices and possibly advance towards the definition of protocols for the use of ion irradiation as a tool to evaluate radiation effects on materials. Nineteen modelling codes across different scales are being used and developed and an experimental validation programme based on the examination of materials irradiated with neutrons and ions is being carried out. The project enters now its 4th year and is close to delivering high-quality results. This paper overviews the work performed so far within the project, highlighting its impact for fission and fusion materials science.

Permalink: https://www.hzdr.de/publications/Publ-33052
Publ.-Id: 33052


Metal–Insulator Transition via Ion Irradiation in Epitaxial La0.7Sr0.3MnO3-δ Thin Films

Cao, L.; Herklotz, A.; Rata, D.; Yin, C.; Petracic, O.; Kentsch, U.; Helm, M.; Zhou, S.

Complex oxides provide rich physics related to ionic defects. For the proper tuning of functionalities in oxide heterostructures, it is highly desired to develop fast, effective and low temperature routes for the dynamic modification of defect concentration and distribution. In this work, we report on the use of helium-implantation to efficiently control the vacancy profiles in epitaxial La0.7Sr0.3MnO3-δ thin films. The viability of this approach is supported by lattice expansion in the out-of-plane lattice direction and dramatic change in physical properties, i.e., a transition from ferromagnetic metallic to antiferromagnetic insulating. In particular, a significant increase of resistivity up to four orders of magnitude is evidenced at room temperature, upon implantation of highly energetic He-ions. Our result offers an attractive means for tuning the emergent physical properties of oxide thin films, via strong coupling between strain, defects and valence.

Permalink: https://www.hzdr.de/publications/Publ-33050
Publ.-Id: 33050


APR files

Nour, A.

APR  files for 4 different functions

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-24
    DOI: 10.14278/rodare.1134
    License: CC-BY-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-33049
Publ.-Id: 33049


Internal Access: Full source data of publication: "Tumor irradiation in mice with a laser-accelerated proton beam"

Kroll, F.; Brack, F.-E.; Bernert, C.; Bock, S.; Bodenstein, E.; Brüchner, K.; Cowan, T.; Gaus, L.; Gebhardt, R.; Helbig, U.; Karsch, L.; Kluge, T.; Kraft, S.; Krause, M.; Leßmann, E.; Masood, U.; Meister, S.; Metzkes-Ng, J.; Nossula, A.; Pawelke, J.; Pietzsch, J.; Püschel, T.; Reimold, M.; Rehwald, M.; Richter, C.; Schlenvoigt, H.-P.; Schramm, U.; Umlandt, M. E. P.; Ziegler, T.; Zeil, K.; Beyreuther, E.

All source data and scripts for publication: "Tumor irradiation in mice with a laser-accelerated proton beam"

Keywords: Laser acceleration; TNSA; Radiobiology; FLASH

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-23
    DOI: 10.14278/rodare.1130

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-33048
Publ.-Id: 33048


Source Data: Tumor irradiation in mice with a laser-accelerated proton beam (Open Access)

Kroll, F.; Brack, F.-E.; Bernert, C.; Bock, S.; Bodenstein, E.; Brüchner, K.; Cowan, T.; Gaus, L.; Gebhardt, R.; Helbig, U.; Karsch, L.; Kluge, T.; Kraft, S.; Krause, M.; Leßmann, E.; Masood, U.; Meister, S.; Metzkes-Ng, J.; Nossula, A.; Pawelke, J.; Pietzsch, J.; Püschel, T.; Reimold, M.; Rehwald, M.; Richter, C.; Schlenvoigt, H.-P.; Schramm, U.; Umlandt, M. E. P.; Ziegler, T.; Zeil, K.; Beyreuther, E.

Source data for all figures of publication: "Tumor irradiation in mice with a laser-accelerated proton beam". Folder structure according to figures.

Keywords: Laser acceleration; TNSA; Radiobiology; FLASH

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-23
    DOI: 10.14278/rodare.1128
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33047
Publ.-Id: 33047


Layer-Dependent Band Gaps of Platinum-Dichalcogenides

Li, J.; Kolekar, S.; Ghorbani Asl, M.; Lehnert, T.; Biskupek, J.; Kaiser, U.; Krasheninnikov, A.; Batzill, M.

Owing to the relatively strong inter-layer interaction, the platinum-dichalcogenides exhibit tunability of their electronic properties by controlling the number of layers. Both PtSe2 and PtTe2 display a semi-metal to semi-conductor transition as they are reduced to bi- or single-layer. The value of the fundamental band gap, however, has been inferred only from density functional theory (DFT) calculations, which are notoriously challenging, as different methods give different results, and currently there is no experimental data. Here we determine the band gap as a function of the number of layers by local scanning tunneling spectroscopy on MBE-grown PtSe2 and PtTe2 islands. We find band gaps of 1.8 eV and 0.6 eV for mono- and bi-layer PtSe2, respectively, and 0.5 eV for monolayer PtTe2. Tri-layer PtSe2 and bilayer PtTe2 are semi-metallic. The experimental data are compared to DFT calculations carried out at different levels of theory. The calculated band gaps may differ significantly from the experimental values, emphasizing the importance of the experimental work. We further show that the variations in the calculated fundamental band gap in bilayer PtSe2 are related to the computed separation of the layers, which depends on the choice of the van der Waals functional. This sensitivity of the band gap to inter-layer separation also suggests that the gap can be tuned by uniaxial stress and our simulations indicate that only modest pressures are required for a significant reduction of the gap, making Pt-dichalcogenides suitable materials for pressure-sensing.

Keywords: 2D materials; layer dependence; PtSe2; PtTe2; scanning tunneling spectroscopy; van der Waals materials; transition metal dichalcogenides

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  • Secondary publication expected from 16.08.2022

Permalink: https://www.hzdr.de/publications/Publ-33046
Publ.-Id: 33046


Elektrische Energiespeicherung mit Flüssigmetallen und Salzschmelzen

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

Stationäre Elektroenergiespeicher können helfen, momentane Differenzen von Elektrizitätsangebot und -nachfrage zu balancieren. Mit zunehmender Nutzung volatiler Stromquellen wird diese Aufgabe wichtiger. Dabei stehen verschiedene Speichertechnologien untereinander,
aber auch mit Alternativen im Wettbewerb.
Flüssigmetallbatterien sind Hochtemperaturspeicher. Sie basieren
auf der stabilen Dichteschichtung eines Alkalimetalls, einer Salzschmelze und eines Schwermetalls. Vermittelt durch die hohe Betriebstemperatur, die über den Schmelztemperaturen der einzelnen Phasen liegen
muss, verlaufen Grenzflächenreaktionen und Transportvorgänge sehr
rasch, was in hohen Strom- und Leistungsdichten resultiert. Der vollständig flüssige Zellinhalt ermöglicht einerseits eine konzeptionell einfache Skalierbarkeit auf Zellebene, die sehr günstige energiebezogene
Investitionskosten verspricht. Andererseits gewinnen durch den flüssige Aggregatzustand strömungsmechanische Vorgänge, die eng an den
Ladungstransport und -übergang gekoppelt sind, stark an Bedeutung.
Der Vortrag wird sowohl ausgewählte physikalische Phänomene in
Flüssigmetallbatterien vorstellen, als auch ihre mögliche Rolle in einem
zukünftigen Energiesystem diskutieren.

Keywords: liquid metal batteries; energy storage

  • Invited lecture (Conferences) (Online presentation)
    84. Jahrestagung der DPG und DPG-Tagung der Sektion Kondensierte Materie, 27.09.-01.10.2021, virtuell, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-33043
Publ.-Id: 33043


data set ELBE experiment POS19101496, Sabrina Fernandes, Rez, CZ

Wagner, A.; Liedke, M. O.; Butterling, M.; Hirschmann, E.; Elsherif, A. G. A.

Positron annihilation lifetime spectroscopy data for ELBE experiment POS19101496 by Sabrina Fernandes, Rez, CZ

Keywords: positron annihilation lifetime spectroscopy; depth dependence; ion irradiation

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-19
    DOI: 10.14278/rodare.1122

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Permalink: https://www.hzdr.de/publications/Publ-33041
Publ.-Id: 33041


Rapid synthesis of gold-palladium core-shell aerogels for selective and robust electrochemical CO2 reduction

Du, R.; Jin, W.; Wu, H.; Hübner, R.; Zhou, L.; Xue, G.; Hu, Y.; Eychmüller, A.

Noble metal aerogels (NMAs), one class of the youngest members in the aerogel family, have drawn increasing attention in the last decade. Featuring the high catalytic activity of noble metals and a 3D self-supported porous network of the aerogels, they have displayed profound potential for electrocatalysis. However, considerable challenges reside in the rapid fabrication of NMAs with a well-tailored architecture, constraining the manipulation of their electrochemical properties for optimized performance. Here, a disturbance-assisted dynamic shelling strategy is developed, generating self-supported Au–Pd core–shell gels within 10 min. Based on suitable activation and desorption energies of the involved species as suggested by theoretical calculations, the Au–Pd core–shell aerogel manifests outstanding CO selectivity and stability at low overpotential (faradaic efficiency > 98% at -0.5 V vs. RHE over 12 hours) for the electrochemical CO2 reduction reaction (CO2RR). The present strategy offers a new perspective to facilely design architecture-specified high-performance electrocatalysts for the CO2RR.

Permalink: https://www.hzdr.de/publications/Publ-33038
Publ.-Id: 33038


Integrated complementary inverters and ring oscillators based on vertical-channel dual-base organic thin-film transistors

Guo, E.; Xing, S.; Dollinger, F.; Hübner, R.; Wang, S.-J.; Wu, Z.; Leo, K.; Kleemann, H.

Lateral-channel dual-gate organic thin-film transistors have been used in pseudo complementary metal-oxide-semiconductor (CMOS) inverters to control switching voltage. However, their relatively long channel lengths, combined with the low charge carrier mobility of organic semiconductors, typically leads to slow inverter operation. Vertical-channel dual-gate organic thin-film transistors are a promising alternative because of their short channel lengths, but the lack of appropriate p- and n-type devices has limited the development of complementary inverter circuits. Here, we show that organic vertical n-channel permeable single- and dual-base transistors, and vertical p-channel permeable base transistors can be used to create integrated complementary inverters and ring oscillators. The vertical dual-base transistors enable switching voltage shift and gain enhancement. The inverters exhibit small switching time constants at 10 MHz, and the seven-stage complementary ring oscillators exhibit short signal propagation delays of 11 ns per stage at a supply voltage of 4 V.

Permalink: https://www.hzdr.de/publications/Publ-33037
Publ.-Id: 33037


Data for: On Inter-bubble Distances and Bubble Clustering in Bubbly Flows: An Experimental Study

Kipping, R.; Hampel, U.

This data set contains the processed data from ultrafast X-ray tomography measurements in a bubble column. Measurements were performed in a bubble column with 100 mm inner diameter and with deionized water and nitrogen as liquid and gas phase, respectively. This data set contains the measurement from the measurement height located 0.7m above the gas sparger. 

Hydrodynamic data, such as bubble size distribution and gas holdup distribution are provided. Furthermore, inter-bubble distances of gas bubbles (distance of the nearest neighbours) are given.

Further detailes on the experiments and the processed data is provided in the corresponding journal paper.

Keywords: bubbly flows; clustering; UFXCT

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-12
    DOI: 10.14278/rodare.1112

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Permalink: https://www.hzdr.de/publications/Publ-33036
Publ.-Id: 33036


Data publication: FPGA-based Real-Time Data Acquisition for Ultrafast X-Ray Computed Tomography

Windisch, D.; Knodel, O.; Juckeland, G.; Hampel, U.; Bieberle, A.

This data contains the firmwares used for all descirbed tests in the paper.

Keywords: Computed tomography; Data acquisition; Field programmable gate arrays

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-16
    DOI: 10.14278/rodare.1118

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Permalink: https://www.hzdr.de/publications/Publ-33035
Publ.-Id: 33035


Evidence of collision-induced resuspension of microscopic particles from a monolayer deposit

Banari, A.; Henry, C.; Fank Eidt, R. H.; Pierre, L.; Klaus, Z.; Hampel, U.; Lecrivain, G.

The present Letter addresses the resuspension of microscopic glass particles from a monolayer bed into a turbulent gas flow. With an intermediate surface coverage, here set to about 10% of the field of view, we report two distinct detachment mechanisms. At relatively low flow velocities, few loosely adhering particles move on the wall to eventually collide with neighboring particles resulting in a clustered resuspension. At higher fluid velocities, mostly individual particles resuspend due to their interaction with the turbulent flow. The resuspension curve, showing the remaining particle fraction as a function of the flow velocity, exhibits a strong bimodal character.

Keywords: paticle resuspension; Inter-particle collisions; experimental test

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Permalink: https://www.hzdr.de/publications/Publ-33034
Publ.-Id: 33034


A stable home: Autocorrelated Kernel Density Estimated home ranges of the critically endangered Elongated Tortoise

Montano, Y.; Michael Marshall, B.; Ward, M.; Simoes Silva, I. M.; Artchawakom, T.; Waengsothorn, S.; Strine, C. T.

Home range is a fundamental concept in ecology used to describe animal space use over their lifetimes. Numerous studies use a variety of metrics to quantify home range; however, most of these treat spatial data inappropriately. Here we re-analyse a publicly available data-set, collected by the authors of this study, using a relatively novel and appropriate home range metric Autocorrelated Kernel Density Estimators (AKDE). Our data includes the movements of 17 Elongated Tortoises (Indotestudo elongata; 12 females, 5 males) located on average once every three days for an average duration of 353.76 ±33.10 days. We found 14 of 17 individuals appear to be occupying a stable home range (using variograms to determine range residency). We made use of AKDEs bias-mitigating measures to counteract the low effective sample sizes stemming from low temporal resolution radio-tracking data. The average AKDE home range for all 14 individuals with range residency was 44.81 ±10.44 ha. Bayesian Regression Models suggest considerable overlap between male and female home range estimates despite males being physically larger than females in both mass and carapace length. These home range estimates have the added utility of being comparable with other studies, less susceptible to errors from a suboptimal tracking regime, and are optimised with code and data for inclusion in future meta-analyses.

Keywords: ecology; testudine; autocorrelated kernel density estimator; spatial ecology; space use; Thailand; Indotestudo elongata

Permalink: https://www.hzdr.de/publications/Publ-33031
Publ.-Id: 33031


Data and code for: Lots of movement, little progress: A review of reptile home range literature

Crane​, M.; Simoes Silva, I. M.; Marshall, B. M.; Strine​, C. T.

Datasets, R code and figures pertaining to the manuscript: Crane, M., Silva, I., Marshall, B. M., & Strine, C. T. (2021). Lots of movement, little progress: A review of reptile home range literature. PeerJ, 9, e11742. DOI: 10.7717/peerj.11742

Keywords: ecology; reptiles; home range; open science; reproducibility; biotelemetry; space use; spatial ecology

Related publications

Permalink: https://www.hzdr.de/publications/Publ-33030
Publ.-Id: 33030


Lots of movement, little progress: A review of reptile home range literature

Crane​, M.; Simoes Silva, I. M.; Marshall, B. M.; Strine​, C. T.

Reptiles are the most species-rich terrestrial vertebrate group with a broad diversity of life history traits. Biotelemetry is an essential methodology for studying reptiles as it compensates for several limitations when studying their natural history. We evaluated trends in terrestrial reptile spatial ecology studies focusing upon quantifying home ranges for the past twenty years. We assessed 290 English-language reptile home range studies published from 2000–2019 via a structured literature review investigating publications’ study location, taxonomic group, methodology, reporting, and analytical techniques. Substantial biases remain in both location and taxonomic groups in the literature, with nearly half of all studies (45%) originating from the USA. Snakes were most often studied, and crocodiles were least often studied, while testudines tended to have the greatest within study sample sizes. More than half of all studies lacked critical methodological details, limiting the number of studies for inclusion in future meta-analyses (55% of studies lacked information on individual tracking durations, and 51% lacked sufficient information on the number of times researchers recorded positions). Studies continue to rely on outdated methods to quantify space-use (including Minimum Convex Polygons and Kernel Density Estimators), often failing to report subtleties regarding decisions that have substantial impact on home range area estimates. Moving forward researchers can select a suite of appropriate analytical techniques tailored to their research question (dynamic Brownian Bridge Movement Models for within sample interpolation, and autocorrelated Kernel Density Estimators for beyond sample extrapolation). Only 1.4% of all evaluated studies linked to available and usable telemetry data, further hindering scientific consensus. We ultimately implore herpetologists to adopt transparent reporting practices and make liberal use of open data platforms to maximize progress in the field of reptile spatial ecology.

Keywords: ecology; reptiles; home range; open science; reproducibility; biotelemetry; space use; spatial ecology

Related publications

Permalink: https://www.hzdr.de/publications/Publ-33029
Publ.-Id: 33029


Simulating Multi Layer Targets for Grazing Incidence Small Angle X-ray Scattering

Paschke-Brühl, F.-L.

This bachelor thesis studies the feasibility of grazing-incidence small-angle x-ray scattering
(GISAXS) in the UHI laser-target interaction via computational simulations with SMILEI. In
this work we briefly analyze the front and back of the target. We find predominantly that the
compression of the target becomes apparent in the GISAXS pattern, while we can not observe
ablation. We will mainly focus on the density oscillation, a dynamic that has not been mentio-
ned in literature yet. The density oscillation dynamics depend on a simple pressure gradient
in between the layers. We observe the multi layers inversely oscillating in density and a global
density alteration moving through the target. The density alteration allows to recognize the
dynamic in a GISAXS pattern. We learn, that GISAXS is feasible in the high intensity regime,
but not for the same dynamics as in the lower intensity regime.

Keywords: GISAXS; SAXS; grazing-incidence small-angle x-ray scattering; SMILEI; Simulation; Density Oscialltion

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-07-27
    DOI: 10.14278/rodare.1116
    License: CC-BY-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-33027
Publ.-Id: 33027


Simulating Multi Layer Targets for Grazing Incidence Small Angle X-ray Scattering

Paschke-Brühl, Franziska-Luise

This bachelor thesis studies the feasibility of grazing-incidence small-angle x-ray scattering
(GISAXS) in the UHI laser-target interaction via computational simulations with SMILEI. In
this work we briefly analyze the front and back of the target. We find predominantly that the
compression of the target becomes apparent in the GISAXS pattern, while we can not observe
ablation. We will mainly focus on the density oscillation, a dynamic that has not been mentio-
ned in literature yet. The density oscillation dynamics depend on a simple pressure gradient
in between the layers. We observe the multi layers inversely oscillating in density and a global
density alteration moving through the target. The density alteration allows to recognize the
dynamic in a GISAXS pattern. We learn, that GISAXS is feasible in the high intensity regime,
but not for the same dynamics as in the lower intensity regime.

Keywords: GISAXS; SAXS; grazing incidence small angle x-ray scattering; SMILEI; Simulation; Density Oscillation

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-07-15
    DOI: 10.14278/rodare.1114
    License: CC-BY-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-33026
Publ.-Id: 33026


NeuLAND: The High-Resolution Neutron Time-of-Flight Spectrometer for R³B at FAIR

Boretzky, K.; Gašparic, I.; Heil, M.; Mayer, J.; Heinz, A.; Caesar, C.; Kresan, D.; Simon, H.; Törnqvist, H. T.; Körper, D.; Alkhazov, G.; Atar, L.; Aumann, T.; Bemmerer, D.; Bondarev, S. V.; Bott, L. T.; Chakraborty, S.; Cherciu, M. I.; Chulkov, L. V.; Ciobanu, M.; Datta, U.; de Filippo, E.; Douma, C. A.; Dreyer, J.; Elekes, Z.; Enders, J.; Galaviz, D.; Geraci, E.; Gnoffo, B.; Göbel, K.; Golovtsov, V. L.; Gonzalez Diaz, D.; Gruzinsky, N.; Haiduc, M.; Heftrich, T.; Heggen, H.; Hehner, J.; Hensel, T.; Hoemann, E.; Holl, M.; Horvat, A.; Horváth, Á.; Ickert, G.; Ignatov, A.; Jelavi Malencia, D.; Johansson, H. T.; Jonson, B.; Kahlbow, J.; Kalantar-Nayestanaki, N.; Kelic-Heil, A.; Kempe, M.; Koch, K.; Kozlenko, N. G.; Krivshich, A. G.; Kurz, N.; Kuznetsov, V.; Langer, C.; Leifels, Y.; Lihtar, I.; Löher, B.; Machado, J.; Martorana, N. S.; Miki, K.; Nilsson, T.; Nyman, G. H.; Orischin, E. M.; Pagano, E. V.; Pirrone, S.; Politi, G.; Potlog, P.-M.; Rahaman, A.; Reifarth, R.; Rigollet, C.; Röder, M.; Rossi, D. M.; Russotto, P.; Savran, D.; Scheit, H.; Schindler, F.; Stach, D.; Stan, E.; Stomvall Gill, J.; Teubig, P.; Trimarchi, M.; Uvarov, L.; Volknandt, M.; Wagner, A.; Wagner, V.; Wranne, S.; Yakorev, D.; Zanetti, L.; Zilges, A.; Zuber, K.

NeuLAND (New Large-Area Neutron Detector) is the next-generation neutron detector for the R3B (Reactions with Relativistic Radioactive Beams) experiment at FAIR (Facility for Antiproton and Ion Research). NeuLAND detects neutrons with energies from 100 to 1000 MeV, featuring a high detection efficiency, a high spatial and time resolution, and a large multi-neutron reconstruction efficiency. This is achieved by a highly granular design of organic scintillators: 3000 individual submodules with a size of 5x5x250 cm3 are arranged in 30 double planes with 100 submodules each, providing an active area of 250x250 cm2 and a total depth of 3 m. The spatial resolution due to the granularity together with a time resolution of 150 ps ensures high-resolution capabilities. In conjunction with calorimetric properties, a multi-neutron reconstruction efficiency of 50% to 70% for four-neutron events will be achieved, depending on both the emission scenario and the boundary conditions allowed for the reconstruction method. We present in this paper the final design of the detector as well as results from test measurements and simulations on which this design is based.

Keywords: high-energy neutron detection; reactions with relativistic radioactive beams; plastic scintillator scintillator array; multi-neutron detection

Permalink: https://www.hzdr.de/publications/Publ-33023
Publ.-Id: 33023


Data publication: Simulation results of bubble growth and shrinkage using population balance model

Li, J.; Liao, Y.; Lucas, D.; Zhou, P.

This dataset includes the predicted bubble diameter, total bubble number, total bubble volume as well as the bubble number density for the cases described in the associated paper.

Keywords: Stability analysis; Internal CFL condition; Discretization; Population balance equation; Class method; Phase change

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-12
    DOI: 10.14278/rodare.1110
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33022
Publ.-Id: 33022


Laser-induced ionization of ions from liquid alloy ion sources of high brightness

Machalett, F.; Ying, B.; Wustelt, P.; Huth, V.; Kübel, M.; Bischoff, L.; Klingner, N.; Pilz, W.; Stöhlker, T.; Paulus, G. G.

In this work, we have generated ion beam targets of metal and metalloid ions using a high-brightness liquid metal ion source (LMIS) originally applied in focused ion beam systems. Using an eutectic Au-Si alloy as a low melting point source feed material, ions of different ion species were detected: Si^{2+}, Si^+, Au^{2+}, Au^+, Au^{2+}, Au^{3+} and Au^{32+}. The source current between emitter needle and extractor electrode is in the range of 10 - 60 μA and can be adjusted up to about 150 μA. The ion source is characterized by high ion current stability and a suitable emission lifetime of several days, which is limited by the amount of material and can be further increased.
To study the strong-field laser ionization, we used a E x B filter and selected Si^{2+} and Au+ ions as ionic targets, because of their high beam intensity. We investigated ultrafast laser-induced ionization, which leads to higher charge states after multiple ionization of both ion species. Laser intensities of up to 10^{16} W/cm^2 allow observation of up to 10-fold ionization of Au^+ ions and 3-fold ionization of Si^{2+} ions.
The aim of further work is to extend the available ion beam targets to other elements of the periodic table to study ultrafast laser-induced fragmentation and ionization dynamics of atoms and molecules in strong laser fields. Another goal is the further increase of the density of ion laser targets for more reliable statistics and shorter measurement times. Further steps are technical improvements of ion source and ion optics as well as the investigation of heavy metal dimers such as Au^{2+}.

Keywords: liquid metal ion source; laser intensity; ultrafast laser-induced fragmentation; ionization dynamics

  • Lecture (Conference) (Online presentation)
    18th SPARC Topical Workshop, 06.-09.09.2021, Darmstadt, Germany

Permalink: https://www.hzdr.de/publications/Publ-33017
Publ.-Id: 33017


Laser-induced ionization of ions from high brightness ion sources

Machalett, F.; Ying, B.; Wustelt, P.; Huth, V.; Kübel, M.; Bischoff, L.; Klingner, N.; Pilz, W.; Stöhlker, T.; Paulus, G. G.

Au and Si ions from high brightness liquid metal ion sources (LMIS) are used as ionic targets for strong-field laser interaction with femtosecond laser beam. Field ionization processes in the field emission source at electrostatic fields of some 10 V/nm allow the generation of various metallic and metalloid ion beams with charge states such as Au^{2+} and Si^{2+}. Studying the ionization in strong femtosecond laser fields with intensities of up to 1E16 W/cm^2, we observed for these elements charge states up to Au^{11+} and Si^{4+}.

Keywords: liquid metal ion sources; femtosecond laser beam; charge states

  • Lecture (Conference) (Online presentation)
    32nd International Conference on Photonic, Electronic and Atomic Collisions, ViCPEAC2021, 20.-23.07.2021, European XFEL, Germany

Permalink: https://www.hzdr.de/publications/Publ-33016
Publ.-Id: 33016


Experimental and numerical investigations of Ni–Co–SiO2 alloy films deposited by magnetic-field-assisted jet plating

Jiang, W.; Huang, M.; Lao, Y.; Yang, X.; Wang, C.; Tian, Z.; Zhou, S.; Mutschke, G.; Eckert, K.

A new method of magnetic-field-assisted jet plating is presented to manufacture Ni-Co-SiO2 alloy films. The influence of different concentrations of Co2+ ions of the electrolyte is investigated with and without magnetic field to study the resulting properties of the deposits. The texture orientation, surface morphology, magnetic properties and corrosion resistance of the alloy films were characterized. The results show that with increasing Co2+ concentration in conventional jet-plating, the surface morphology changes from a granular crystal structure to a needle-like structure at 30 g/L caused by the hexagonal close-packed (HCP) structure of a large Co content. Differently, the assistance of the magnetic field leads to lower Co content in the films, even at a high Co2+ concentration of 30 g/L. The deposit layer remains in the face-centered cubic (FCC) structure and shows a granular morphology. The magnetic field in general leads to grain refinement and inhibits the abnormal Ni–Co co-deposition. The Ni–Co–SiO2 alloy films obtained by magnetic-field-assisted jet plating have a smooth and dense surface. The best soft magnetic properties and corrosion resistance are obtained at a Co2+ concentration of 20 g/L. The coercivity is as low as 7.5 Oe, and the corrosion current density is as low as 1.12 μA·cm-2 in 3.5 wt% NaCl solution without agitation and at room temperature, clearly showing the advantages of the method for preparing superior soft magnetic materials. In addition, a physical model of magnetic-field-assisted jet plating is established. The magnetic forces and the resulting electrolyte flow are analyzed with the help of numerical simulations, and the influence of the magnetic field on the deposition process is discussed from the perspective of magnetohydrodynamics.

Keywords: Ni–Co–SiO2 alloy film; Magnetic-field-assisted jet plating; Magnetic properties; Numerical simulation

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  • Secondary publication expected from 15.10.2022

Permalink: https://www.hzdr.de/publications/Publ-33014
Publ.-Id: 33014


Increased dephasing length in heavily doped GaAs

Duan, J.; Wang, C.; Vines, L.; Rebohle, L.; Helm, M.; Zeng, Y.-J.; Zhou, S.; Prucnal, S.

Ion implantation of S and Te followed by sub-second flash lamp annealing with peak temperature about 1100 oC is employed to obtain metallic n++-GaAs layers. The electron concentration in annealed GaAs is as high as 5×1019 cm-3, which is several times higher than the doping level achievable by alternative methods. We found that heavily doped n++-GaAs exhibits positive magnetoconductance in the temperature range of 3-80 K, which is attributed to the magnetic field suppressed weak localization. By fitting the magnetoconductance results with Hikami-Larkin-Nagaoka model, it is found that the phase coherence length increases with increasing carrier concentration at low temperature and is as large as 540 nm at 3 K. The temperature dependence of the phase coherence length follows〖 l〗_∅∝T^η (η~0.3), indicating defect-related scattering as the dominant dephasing mechanism. In addition, the high doping level in n-type GaAs provides the possibility to use GaAs as a plasmonic material for chemical sensors operating in the infrared range.

Keywords: ion implantation; heavily doped GaAs; phase coherence length; sub-second annealing; plasmonic

Permalink: https://www.hzdr.de/publications/Publ-33012
Publ.-Id: 33012


Supplementary material: Ph.D. dissertation of Lucas Pereira, TU Bergakademie Freiberg, 2021.

Pereira, L.
Supervisor: Frenzel, Max; Supervisor: Tolosana-Delgado, Raimon; Supervisor: Gutzmer, Jens

This supplementary material supports the Ph.D. dissertation of Lucas Pereira, submitted to the Faculty 3 of the TU Bergakademie Freiberg.

C2.SM1.Percentiles.xlsx: Mentioned in the chapter 2 of the dissertation, this file contains, in terms of percentiles, the distribution of every particle descriptive variable in the different samples used to train the logistic regression models of the case study presented in this chapter.

C2.SM2.Coefficients.xlsx: Mentioned in the chapter 2 of the dissertation, this file contains the complete list of coefficients assigned to each variable, in each separation unit, of the case study presented in this chapter.

C4.SM1.StatWeight.xlsx: Mentioned in the chapter 4 of the dissertation, this file contains a detailed explanation of the statistical weights of particles and how they can be used to integrate a set of particle datasets from different streams and size fractions into a single and balanced training dataset.

Keywords: Geometallurgy; Particle-based separation model

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-09
    DOI: 10.14278/rodare.1104
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33009
Publ.-Id: 33009


On the nature of Pb species in Pb-(over)exchanged zeolite: a combined experimental and theoretical study

Roos, D. P.; Scheinost, A.; Churakov, S. V.; Nagashima, M.; Cametti, G.

Structural properties of Pb-exchanged zeolites are of interest because of their applications in environmental remediation and in industrial processes. In this study, we report on a Pb-exchanged aluminosilicate zeolite (Pb-STI), with particular focus on the cationic species, which form inside the zeolitic pores as a result of the exchange experiments. The produced
zeolite had chemical composition Pb13.4(OH)10Al17.4Si54.6O144 ∙38H2O, indicating a Pb2+ overexchange of approximately 50%. The STI framework maintained the Fmmm space group characteristic of the type material. However, the extraframework occupants, Pb2+, H2O and OH-, were characterized by a strong positional-disorder. The latter was resolved and
interpreted combining Extended X-ray Absorption Fine Structure (EXAFS) analysis with Molecular Dynamics (MD) simulations. On average, Pb2+ ions are coordinated by 2 OH- and
1 H2O at distances < 2.5 Å, whereas bonds to framework oxygen-atoms were found only at longer distances (> 2.8 Å). Pb2+ adopts mainly a sided distorted coordination, indicating a
stereochemical activity of the lone pair electrons. The obtained results were compared with those of other mono-cationic forms of STI zeolites. Based on the analysis of the framework
distortion experienced after the incorporation of different metal ions, considerations are drawn on the potential effect of Pb2+ on the thermal stability of STI framework type zeolites.

Keywords: XAFS; Zeolite; XRD; Molecular dynamics; DFT

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  • Secondary publication expected from 20.09.2022

Permalink: https://www.hzdr.de/publications/Publ-33007
Publ.-Id: 33007


Compact spectroscopy of keV to MeV X-rays from a laser wakefield accelerator

Hannasch, A.; Laso García, A.; La Berge, M.; Zgadzaj, R.; Köhler, A.; Couperus Cabadağ, J. P.; Zarini, O.; Kurz, T.; Ferrari, A.; Molodtsova, M.; Naumann, L.; Cowan, T.; Schramm, U.; Irman, A.; Downer, M.

We reconstruct spectra of secondary X‑rays from a tunable 250–350 MeV laser wakefield electron accelerator from single‑shot X‑ray depth‑energy measurements in a compact (7.5 × 7.5 × 15 cm), modular X‑ray calorimeter made of alternating layers of absorbing materials and imaging plates. X‑rays range from few‑keV betatron to few‑MeV inverse Compton to > 100 MeV bremsstrahlung emission, and are characterized both individually and in mixtures. Geant4 simulations of energy deposition of single‑energy X‑rays in the stack generate an energy‑vs‑depth response matrix for a given stack configuration. An iterative reconstruction algorithm based on analytic models of betatron, inverse Compton and bremsstrahlung photon energy distributions then unfolds X‑ray spectra,
typically within a minute. We discuss uncertainties, limitations and extensions of both measurement and reconstruction methods.

Permalink: https://www.hzdr.de/publications/Publ-33005
Publ.-Id: 33005


Data publication: Broadband frequency filters with quantum dot chains

Ehrlich, T.; Schaller, G.

Rohdaten für Abbildungen (*.agr) und Mathematica Notebooks (*.nb) für die Berechnungen

Keywords: thermodynamic uncertainty relation; Levitov-Lesovik formula; transmission; reaction-coordinate mapping

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-05
    DOI: 10.14278/rodare.1101
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33004
Publ.-Id: 33004


Automated mineralogy particle dataset: dry magnetic separation of skarn ore

Buchmann, M.; Kern, M.; Pereira, L.; Frenzel, M.; Tolosana Delgado, R.; van den Boogaart, K. G.; Gutzmer, J.

This data set origins from the AFK (“Aufbereitung feinkörniger Komplexerze”, BMBF grant number 033R128) project. The main target within this project was to produce a cassiterite concentrate, which is suitable for the subsequent production of tin. Various processing steps and the material specific behaviour were investigated within the progress of the project. The present data set derives from dry magnetic separation tests. More information can be found in the "readme.pdf" file attached.

Keywords: Geometallurgy; Particle-based separation modelling; Magnetic separation; Cassiterite

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-04
    DOI: 10.14278/rodare.1095
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33003
Publ.-Id: 33003


Data publication: Microscopic and spectroscopic bioassociation study of uranium(VI) with an archaeal Halobacterium isolate

Hilpmann, S.; Bader, M.; Steudtner, R.; Müller, K.; Stumpf, T.; Cherkouk, A.

Bei diesem Datensatz handelt es sich um die Primärdaten der Untersuchung der Wechselwirkungen eines halophilen Archaeons mit Uran(VI). Dazu wurden Konzentrationsbestimmungen mittels ICP-MS durchgeführt, Lumineszenzspektren mittels zeitaufgelöster laserinduzierter Lumineszenzspektroskopie und IR Spektren aufgenommen. Darüber hinaus wurden Bilder der Zellen mit Hilfe der Fluoreszenzmikroskopie aufgenommen.

Keywords: uranium(VI) bioassociation; halophilic archaea; rock salt

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-05
    DOI: 10.14278/rodare.1099
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33002
Publ.-Id: 33002


Monte Carlo methods in particle and nuclear physics

Müller, S.

Presentation at HZDR's 2021 summer student seminar

Keywords: Monte Carlo; Simulation

  • Lecture (Conference) (Online presentation)
    Summer Student seminar series, 27.07.2021, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-33001
Publ.-Id: 33001


P2001 - Vorrichtung zur gezielten Anordnung von in einem Analyten gelösten, elektrisch polarisierbaren Materialien, Verfahren zur Bestimmung eines isoelektrischen Punktes eines elektrisch isolierenden Materials, Verfahren zum gezielten Anordnen eines in einem Analyten gelösten elektrisch polarisierbaren Materials

Rebohle, L.; Fischer, C.; Skorupa, I.; Schmidt, H.; Krüger, S.; Blaschke, D.

Es wird eine Vorrichtung (10) zur gezielten Anordnung eines in einem Analyten gelösten, elektrisch polarisierbaren Materials (4), aufweisend eine siliziumhaltige Trägerstruktur (3), eine elektrisch isolierende erste Deckstruktur (1) mit einem ersten isoelektrischen Punkt und eine elektrisch isolierende zweite Deckstruktur (2) mit einem zweiten isoelektrischen Punkt vorgeschlagen, wobei der erste isoelektrische Punkt vom zweiten isoelektrischen Punkt verschieden ist. Weiterhin werden ein Verfahren zur Bestimmung eines ersten isoelektrischen Punktes eines Materials sowie ein Verfahren zum gezielten Anordnen eines in einem Analyten gelösten, elektrisch polarisierbaren Materials (4) vorgeschlagen.

  • Patent
    DE102020200470 - Erteilung 20.05.2021; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32998
Publ.-Id: 32998


P1916 - Verfahren und Anordnung zum Charakterisieren der Positionierung eines Objekts

Hampel, U.

Die Erfindung betrifft ein Verfahren und eine Anordnung zum Charakterisieren der Positionierung eines Objekts innerhalb eines Aufenthaltsbereichs, wobei mittels eines Myonenteleskops darauf auftreffende Myonen als Myonenteleskop-Detektionsereignisse und deren Myonentrajektorien als Myonentrajektorien-Daten erfasst werden, wobei zudem mittels eines objektseitigen Myonendetektors darauf auftreffende Myonen als Myonendetektor-Detektionsereignisse erfasst werden, und wobei quasizeitgleiche Myonenteleskop-Detektionsereignisse und Myonendetektor-Detektionsereignisse ermittelt werden und basierend auf den zugehörigen Myonentrajektorien-Daten die Positionierung des Objekts charakterisiert wird.

  • Patent
    DE102019131006 - Erteilung 01.10.2020

Permalink: https://www.hzdr.de/publications/Publ-32997
Publ.-Id: 32997


P1915 - Magnetische Streufeld-Struktur, magnonisches Bauelement und Verfahren zur Herstellung einer magnetischen Streufeldstruktur

Samad, F.; Koch, L.; Arekapudi, S. S. P. K.; Hellwig, O.; Schultheiß, H.

Eine magnetische Struktur (510) weist einen synthetischen antiferromagnetischen Schichtstapel (100) mit senkrechter magnetischer Anisotropie auf. Ein erster und ein zweiter Teilbereich (110, 120) des synthetischen antiferromagnetischen Schichtstapels (100) sind lateral nebeneinander ausgebildet. Eine vertikaler erster Magnetisierungsverlauf im ersten Teilbereich (110) unterscheidet sich nach Betrag und/oder Orientierung von einem vertikalen zweiten Magnetisierungsverlauf im zweiten Teilbereich (120). Auf einer horizontalen Hauptoberfläche (101) des synthetischen antiferromagnetischen Schichtstapels (100) kann eine Entkopplungsschicht (200) ausgebildet sein. Auf der Entkopplungsschicht (200) oder der Hauptoberfläche (101) ist eine Funktionsschicht (300) ausgebildet. Die Funktionsschicht (300) wird lokal durch Kopplung mit dem synthetischen antiferromagnetischen Schichtstapel (100)oder durch die Streufelder des synthetischen antiferromagnetischen Schichtstapels (100)in ihrer Magnetisierung ausgerichtet, wodurch in der Funktionsschicht (300) beispielsweise eine variable und reprogrammierbare Infrastruktur für die Erzeugung, Verarbeitung, Übertragung und Detektion von Spinwellen erzeugt werden kann.

  • Patent
    DE102019129203 - Offenlegung 29.04.2021

Permalink: https://www.hzdr.de/publications/Publ-32996
Publ.-Id: 32996


P1909 - Mehrphasen-Messsystem mit Kalibrierwertnachführung und strömungstechnische Anordnung

Wiedemann, P.; Flaisz, A.; Schleicher, E.

Ein Mehrphasen-Messsystem (100) für ein mehrphasiges Fluid (205) weist eine Referenzwert-Messanordnung (160) und eine Mehrphasen-Messeinrichtung (130) auf. Die Referenzwert-Messanordnung (160) weist mindestens eine Kapillare (110) und eine Kapillaren- Messeinrichtung (120) auf. Innere Querschnittsfläche und Länge der Kapillare (110) sind so bemessen, dass bei Durchströmung der Kapillare (110) Phasen des mehrphasigen Fluids (205) in Durchströmungsrichtung separieren. Die Kapillaren-Messeinrichtung (120) ist zur Bestimmung mindestens einer physikalischen Eigenschaft mindestens einer der durch die Kapillare (110) fließenden Phasen eingerichtet. Das Mehrphasen-Messeinrichtung (130) ist für eine Messung
eines Volumen- und/oder Massenanteils von mindestens einer Phase des mehrphasigen Fluids und/oder für eine Messung eines Volumen- und/oder Massenstromes von mindestens einer der Phasen des mehrphasigen Fluids unter Berücksichtigung der durch die Kapillaren-Messeinrichtung (120) bestimmten physikalischen Eigenschaft(en) eingerichtet.

  • Patent
    DE102019125243 - Offenlegung 25.03.2021; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32995
Publ.-Id: 32995


P1908 - Verfahren zum Herstellen eines gedruckten magnetischen Funktionselements und gedrucktes magnetisches Funktionselement

Canon Bermudez, G. S.; Mönch, J. I.; Makarov, D.

Die vorliegende Erfindung betrifft ein Verfahren zum Herstellen eines gedruckten magnetischen Funktionselements, bei dem ein Substrat (1) auf einer Oberfläche mit mindestens einem Kontakt (2) aus einem elektrisch leitfähigen Werkstoff versehen wird. Nachfolgend wird auf den oder an den mindestens einen Kontakt (2) und diesen unmittelbar berührend eine Struktur (3) aus einem einen magnetoresistiven Effekt aufweisenden Werkstoff als Paste, als Gel, als Dispersion oder als Suspension aufgedruckt sowie die Struktur (3) durch eine Bestrahlung mit elektromagnetischer Strahlung über einen Zeitraum im Millisekundenbereich elektrisch leitfähig und magnetfeldempfindlich.

  • Patent
    DE102019211970 - Offenlegung 11.02.2021; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32994
Publ.-Id: 32994


P1907 - Deuterierte 7-(3-(4-(2-([18F]Fluor)ethoxy)phenyl)propyl)-2-(furan-2-yl)-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amin-Derivate

Lai, T. H.; Teodoro, R.; Toussaint, M.; Gündel, D.; Deuther-Conrad, W.; Dukic-Stefanovic, S.; Schröder, S.; Moldovan, R.-P.; Brust, P.

Die Erfindung betrifft eine Verbindung der allgemeinen Formel I worin die Reste X1a, X1b, X2a, X2b, X3a, X3b, X4a, X4b, X5a und X5b unabhängig voneinander jeweils Wasserstoff oder Deuterium sind, mit der Maßgabe, dass zumindest einer der Reste X1a, X1b, X2a, X2b, X3a, X3b, X4a, X4b, X5a und X5b Deuterium ist.

  • Patent
    DE102019116986 - Offenlegung 24.12.2020; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32993
Publ.-Id: 32993


P1906 - 3-(4-Amino-2-methoxyphenyl)-2-cyanoacrylsäure-Derivate und deren Verwendung als Präkursoren für die Herstellung radiochemischer Verbindungen

Moldovan, R.-P.; Sadeghzadeh, M.; Wenzel, B.; Kranz, M.; Teodoro, R.; Ludwig, F.-A.; Fischer, S.; Toussaint, M.; Deuther-Conrad, W.; Brust, P.

Die Erfindung betrifft eine Verbindung der allgemeinen Formel (E)-I oder (Z)-I worin Y eine Hydroxygruppe oder eine O-M+-Gruppe ist, wobei M+ ein Kation ist; Z1 aus der Gruppe ausgewählt ist, die aus einer substituierten oder unsubstituierten C1-C12-Alkylgruppe, einer substituierten oder unsubstituierten C2-C12-Alkenylgruppe, einer substituierten oder unsubstituierten C2-C12-Alkinylgruppe, einer substituierten oder unsubstituierten Arylgruppe, einer substituierten oder unsubstituierten Heteroarylgruppe, einer substituierten oder unsubstituierten Alkylarylgruppe, einer substituierten oder unsubstituierten Arylalkylgruppe und einer Gruppe -A1-X besteht, worin A1 eine Kohlenwasserstoffkette mit ein bis vier substituierten oder unsubstituierten Methylengruppen ist, wobei in der Kohlenwasserstoffkette zumindest ein Sauerstoffatom unter Ausbildung einer Ethergruppe angeordnet sein kann, und X aus der Gruppe ausgewählt ist, die aus einer Methylgruppe, einem Halogen und einer Hydroxygruppe besteht; und Z2 ein Rest ist, der eine Abgangsgruppe AG trägt, wobei Z2 aus der Gruppe ausgewählt ist, die aus einer substituierten oder unsubstituierten C1-C12-Alkylgruppe, einer substituierten oder unsubstituierten C2-C12-Alkenylgruppe, einer substituierten oder unsubstituierten C2-C12-Alkinylgruppe, einer substituierten oder unsubstituierten Arylgruppe, einer substituierten oder unsubstituierten Heteroarylgruppe, einer substituierten oder unsubstituierten Alkylarylgruppe und einer substituierten...

  • Patent
    DE102019112040 - Offenlegung 12.11.2020; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32992
Publ.-Id: 32992


P1905 - N-(4-methoxy-7-morpholinobenzo[d]thiazol-2-yl)-acetamid-Derivate und deren Verwendung

Lai, T. H.; Teodoro, R.; Moldovan, R.-P.; Kranz, M.; Dukic-Stefanovic, S.; Toussaint, M.; Spalholz, T.; Deuther-Conrad, W.; Brust, P.

Die Erfindung betrifft eine Verbindung der allgemeinen Formel I (Formel I)
worin Ar eine Phenylgruppe oder eine Pyridylgruppe ist; R1 Wasserstoff oder eine Nitrogruppe ist; und R2 Fluor oder eine Abgangsgruppe ist, wobei die Abgangsgruppe aus der Gruppe ausgewählt ist, die aus einer Nitrogruppe, einem Halogen, einem Diazoniumion oder -salz, einem Trialkylammoniumion oder -salz, einem Dialkoxyaren, einem Sulfoxid, einer Boronsäure, einem Boronsäureester, Alkylzinn, Arylzinn, einem Iodoniumion oder -salz, einem Iodonium-Ylid und einem Sulfonsäureester besteht.

  • Patent
    DE102019110904 - Offenlegung 29.10.2020

Permalink: https://www.hzdr.de/publications/Publ-32991
Publ.-Id: 32991


P1904 - Verwendung eines Komplexierungsmittels zur Rückgewinnung von Metallionen aus Industrieabwasser sowie ein Verfahren dazu

Jain, R.; Joshi, T.; Pollmann, K.

Die vorliegende Erfindung betrifft ein neues Komplexierungsmittel zur Rückgewinnung von Metallionen aus Industrieabwasser, aufweisend ein Trägermaterial, an dem Siderophore über einen Linker kovalent immobilisiert sind, wobei der Linker eine Polyethylenglykol-Kette enthält, und wobei der Linker eine Masse von 2000-3500 Da aufweist, sowie ein Verfahren zu dessen Herstellung und die Verwendung des Komplexierungsmittels bei der Rückgewinnung von Metallen aus Industrieabwässern.

  • Patent
    DE102019108803 - Offenlegung 08.10.2020; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32990
Publ.-Id: 32990


P1903 - Anordnung zur berührungslosen Bestimmung der Geschwindigkeitsverteilung eines Schmelzvolumens in einer Stranggusskokille

Ratajczak, M.; Wondrak, T.; Stefani, F.; Primetals Austria

Die Erfindung betrifft eine Anordnung zur berührungslosen Bestimmung einer Geschwindigkeitsverteilung eines Schmelzvolumens in einer Stranggusskokille. Die erfindungsgemäße Anordnung soll eine Messung mit verbesserten Signal-Rausch-Verhältnis ermöglichen und in bestehende Bauteile integriert werden. Die Anordnung weist mindestens eine ein primäres Magnetfeld erzeugende Spule, deren primäres Magnetfeld das Schmelzvolumen durchdringt, und eine Mehrzahl von Magnetfeldsensoren zur Messung des durch die Wechselwirkung der Schmelzbewegung mit dem erzeugten primären Magnetfeld induzierten Magnetfeldes auf. Die Stranggusskokille weist mindestens ein Kokillenelement auf, welches in mindestens einem Bereich mit einem Anschlusselement verbunden ist. Spule und Magnetfeldsensoren sind derart innerhalb des Anschlusselements angeordnet, dass die Magnetfeldsensoren innerhalb des von der Spule umschlossenen Volumens des Anschlusselements angeordnet sind.

  • Patent
    DE102019105628 - Erteilung 19.03.2020; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32989
Publ.-Id: 32989


Data publication: Stretchable Thin Film Mechanical Strain Gated Switches and Logic Gate Functions Based on a Soft Tunneling Barrier

Chae, S.; Jin Choi, W.; Fotev, I.; Bittrich, E.; Uhlmann, P.; Schubert, M.; Makarov, D.; Wagner, J.; Pashkin, O.; Fery, A.

Time-domain THz spectroscopy (raw data) and the analysis of the delay time (Origin file)

Keywords: Strain gated electric switch; logic gates; tunneling; stretchable circuit; thin film

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-03
    DOI: 10.14278/rodare.1092

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-32988
Publ.-Id: 32988


P1902 - Verfahren und Vorrichtung zur Abtrennung von Kunststoffpartikeln

Nikpay, M.

Die Erfindung betrifft eine Verfahren zur Abtrennung von Kunststoffpartikeln aus einer Flüssigkeit oder einem heterogenen Gemisch, das eine Flüssigkeit enthält oder mit einer Flüssigkeit in Kontakt gebracht wird. Dabei ist vorgesehen, dass (a) die Kunststoffpartikel einem Magnetfeld ausgesetzt werden; (b) an der Oberfläche eines Sammlers Kunststoffpartikel adsorbiert werden; und (c) an der Oberfläche des Sammlers adsorbierte Kunststoffpartikel abgeführt werden.

  • Patent
    DE102019103936 - Offenlegung 20.08.2020

Permalink: https://www.hzdr.de/publications/Publ-32986
Publ.-Id: 32986


P1901 - Durchflussmessanordnung und strömungstechnische Anordnung

Arlit, M.; Hampel, U.; Schroth, C.

Eine Durchflussmessanordnung (400) weist einen Messkanal (100) mit einem Messkanaldurchmesser (D0) auf. In dem Messkanal (100) sind ein Strömungsteiler (300) und ein Anemometrie-Gittersensor (500) angeordnet. Der Anemometrie-Gittersensor (500) weist eine Vielzahl von Sensorelementen (510) mit temperaturabhängigem elektrischen Widerstand auf, die lateral voneinander beabstandet sind. Der Strömungsteiler (300) weist eine Vielzahl von Teilkanälen (310) auf. Eine Kanallänge (L1) der Teilkanäle (310) kann kleiner oder gleich dem Messkanaldurchmesser (D0) sein. Ein Abstand (L2) zwischen dem Anemometrie-Gittersensor (500) und dem Strömungsteiler (300) kann kleiner oder gleich dem Messkanaldurchmesser (D0) sein.

  • Patent
    DE102019103674 - Offenlegung 13.08.2020; Nachanmeldungen: WO, EP

Permalink: https://www.hzdr.de/publications/Publ-32985
Publ.-Id: 32985


P1827 - Microfluidic device, apparatus and method for enrichment and dilution of magnetic molecular entities

Mutschke, G.; Yang, X.; AGH Krakau

A microfluidic device (500) includes a substrate (100) with a fluid channel (250) extending from an inlet opening (210) to a channel branch (270). The fluid channel (250) includes a planar spiral portion (255) and at the channel branch (270) 10 the fluid channel (250) branches in at least two outlet channels (280). A ferromagnetic auxiliary structure (300) is formed in a plane parallel to the planar spiral portion (255).

  • Patent
    EP3669982 - Offenlegung 24.06.2020

Permalink: https://www.hzdr.de/publications/Publ-32984
Publ.-Id: 32984


Data publication: A new system for real-time data acquisition and pulse parameterization for digital positron annihilation lifetime spectrometers with high repetition rates

Hirschmann, E.; Butterling, M.; Hernandez Acosta, U.; Liedke, M. O.; Elsherif, A. G. A.; Petring, P.; Görler, M.; Krause-Rehberg, R.; Wagner, A.

Bei diesem Datensatz handelt es sich um die Bilder zur Publikation und Daten für die Leistungskurven

Keywords: Data reduction methods; Digital signal processing (DSP); Detection of defects; Online farms and online filtering

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-03
    DOI: 10.14278/rodare.1090

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-32980
Publ.-Id: 32980


A new system for real-time data acquisition and pulse parameterization for digital positron annihilation lifetime spectrometers with high repetition rates

Hirschmann, E.; Butterling, M.; Hernandez Acosta, U.; Liedke, M. O.; Elsherif, A. G. A.; Petring, P.; Görler, M.; Krause-Rehberg, R.; Wagner, A.

We present a new system for high repetition rate and real-time pulse analysis imple- mented at the Monoenergetic Positron Source (MePS) at the superconducting electron LINAC ELBE at Helmholtz-Zentrum Dresden-Rossendorf. Dedicated digital signal processing and op- timized algorithms are employed allowing for high bandwidth throughput, online pulse analysis and filtering. Positrons generated from radioisotopes and from bremsstrahlung pair production by means of highly intense accelerator-based positron beams serve as a microstructure probe allowing material characterizations with respect to chemical, mechanical, electrical, and magnetic properties. Positron annihilation lifetime events with up to 13 MHz repetition rate are being processed online without losses while performing signal selections for pile-up reduction, online energy calibration, and - for radioisotope-based measurements - identification of start and stop events.

Keywords: Data reduction methods; Digital signal processing (DSP); Detection of defects; Online farms and online filtering

Related publications

Downloads:

  • Secondary publication expected from 02.08.2022

Permalink: https://www.hzdr.de/publications/Publ-32979
Publ.-Id: 32979


Numerical dimensioning of a pre-cooler for sCO2 power cycles to utilize industrial waste heat

Unger, S.

These are the the processed data of the paper "Numerical dimensioning of a pre-cooler for sCO2 power cycles to utilize industrial waste heat". The data contain the heat transfer and fluid dynamic values of the simulation performed for the corresponding article.

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-02
    DOI: 10.14278/rodare.1084
    License: CC-BY-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-32978
Publ.-Id: 32978


Targeting glutamine metabolism and autophagy: the combination for prostate cancer radiosensitization

Mukha, A.; Kahya, U.; Dubrovska, A.

Radiotherapy is one of the curative mainstays of prostate cancer; however, its efficacy is often diminished by tumor radioresistance. Depending on the stage of disease, tumors can relapse in approximately 50% of patients with prostate cancer after radiotherapy. Nevertheless, the mechanisms that drive tumor cell survival are not fully characterized, and reliable molecular prognostic markers of prostate cancer radioresistance are missing. Similar to other tumor entities, prostate cancer cells are heterogeneous in their capability to maintain tumor growth. The populations of cancer stem cells (CSC) with self-renewal and differentiation properties are responsible for tumor development and recurrence after treatment. Eradication of these CSC populations is of utmost importance for efficient tumor cure. In a recently published study, we showed that prostate cancer cells could be radiosensitized by glutamine deprivation, resulting in DNA damage, oxidative stress, epigenetic modifications, and depletion of CSCs. Conversely, prostate cancer cells with resistance to glutamine depletion show an activation of ATG-mediated macroautophagy/autophagy as a survival strategy to withstand radiation-induced damage. Thus, a combination of targeting glutamine metabolism and autophagy blockade lead to more efficient prostate cancer radiosensitization.

Keywords: ATG5; CSC; glutaminase; tricarboxylic acid cycle

Permalink: https://www.hzdr.de/publications/Publ-32974
Publ.-Id: 32974


Experimental characterization of liquid metal bubble-driven flows modeling the situation in a steel ladle

Wondrak, T.; Bruch, C.; Eckert, S.; Gardin, P.; Hackl, G.; Lachmund, H.; Lüngen, H. B.; Odenthal, H.-J.; Timmel, K.; Willers, B.

In metallurgy, gas-liquid two-phase flows are relevant for mixing, degassing and refinement. The reliable prediction of the hydrodynamic performance in gas-stirred ladles is of utmost relevance for optimization and process control. A new experimental facility has been designed and constructed for systematic investigations of gas bubbles rising inside the alloy SnBi, its thermophysical properties are very similar to those of steel. Low operating temperatures (T~200°C) allow the use of powerful measuring techniques. The cylindrical fluid vessel represents a 1:5.25 model of an industrial 185 t ladle and is equipped with a vacuum pump to achieve low-pressure conditions for VOD (Vacuum Oxygen Decarburization) applications as well. The experiments provide a copious data base about the flow regimes, void fraction, liquid and bubble velocities, and bubble properties, which can be used to provide so far unknown boundary conditions for CFD simulations of various metallurgical reactors such as steelmaking converters or steelmaking ladles.

Keywords: two-phase flow; liquid metal; bubble measurement

Permalink: https://www.hzdr.de/publications/Publ-32973
Publ.-Id: 32973


RawData for paper: Mounted Single Particle Characterization for 3D Mineralogical Analysis - MSPaCMAn

Da Assuncao Godinho, J. R.

Raw 3D images of the 3 types of samples used in the paper

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-07-30
    DOI: 10.14278/rodare.1080
    License: CC-BY-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-32972
Publ.-Id: 32972


Manipulation of antiferromagnetism with electric fields: from fundamentals to memory concepts

Makarov, D.

Thin film antiferromagnets (AF) have potential to revolutionize spintronics due to their inherently magnetic-field stable magnetic order and high-frequency operation. To explore their application potential, it is necessary to understand modifications of the magnetic properties and magnetoelectric responses of AF thin films with respect to their bulk counterparts. Considering grainy morphology of thin films, questions regarding the change of the intergranular exchange, criticality behavior and switching of the order parameter need to be addressed.
Our approach is based on the electron transport characterization of magnetic responses of thin film antiferromagnets [1-4]. This task is difficult as minute uncompensated surface magnetization of antiferromagnets needs to be detected, which imposes strict requirements to the sensitivity of the method. We will outline our developments of zero-offset anomalous Hall magnetometry [1] applied to study the physics of conventional metallic IrMn and insulating magnetoelectric Cr2O3 antiferromagnets. To build a reliable description of the material properties, the analysis of the transport data is backed up by structural characterization and real space imaging of AF domain patterns using NV microscopy [2,5]. Based on this unique and novel combination, we for the first time observe the formation of nanoscale antiferromagnetic domains in thin films of Chromia (Cr2O3) across its ordering temperature at ~300 K. Our quantitative results yield a detailed understanding of the domain formation process in Cr2O3 and allow us to determine the efficiency of inter-granular magnetic exchange coupling [5]. This coupling strength has proven decisive in the decades long development of ferromagnetic memory media and will be of equal importance for future antiferromagnetic spintronics technologies.
The fundamental understanding of the magnetic microstructure of magnetoelectric α-Cr2O3 thin films and the possibility to read-out its antiferromagnetic order parameter all-electrically enabled the entirely new recording concept where a magnetoelectric memory cell can be addressed without using a ferromagnet. With this approach, we opened an appealing topic of purely antiferromagnetic magnetoelectric random access memory (AF-MERAM) [2].
By exploring the interaction of antiferromagnetic domain walls with morphological structures prepared on the surface of Cr2O3 single crystals, we access the nanoscale mechanics of AF domain walls [6,7]. We propose to employ nanoscale patterns as engineered pinning centers for AF domain walls, where binary information is encoded by the direction of the Neel vector. Our results bear significant potential for technological exploitation be it in the form of the proposed antiferromagnetic memory devices, or ultimately for the realisation of DW logic using antiferromagnets.
These recent developments on the fabrication and characterization of Cr2O3-based functional elements will be discussed in this presentation.

[1] T. Kosub, M. Kopte, F. Radu, O. G. Schmidt, D. Makarov, “All-Electric access to the Magnetic-Field-Invariant Magnetization of Antiferromagnets”, Phys. Rev. Lett. 115, 097201 (2015).
[2] T. Kosub, M. Kopte, R. Hühne, P. Appel, B. Shields, P. Maletinsky, R. Hübner, M. O. Liedke, J. Fassbender, O. G. Schmidt, and D. Makarov, “Purely antiferromagnetic magnetoelectric random access memory”, Nature Communications 8, 13985 (2017).
[3] R. Schlitz, T. Kosub, A. Thomas, S. Fabretti, K. Nielsch, D. Makarov, and S. T. B. Goennenwein, “Evolution of the spin hall magnetoresistance in Cr2O3/Pt bilayers close to the Neel temperature”, Appl. Phys. Lett. 112, 132401 (2018).
[4] P. Muduli, R. Schlitz, T. Kosub, R. Hübner, A. Erbe, D. Makarov, and S. T. B. Goennenwein, “Local and nonlocal spin Seebeck effect in lateral Pt-Cr2O3-Pt devices at low temperatures”, Appl. Phys. Lett. Materials 9, 021122 (2021).
[5] P. Appel, B. J. Shields, T. Kosub, R. Hübner, J. Fassbender, D. Makarov, and P. Maletinsky, “Nanomagnetism of magnetoelectric granular thin film antiferromagnets”, Nano Letters 19, 1682 (2019).
[6] O. V. Pylypovskyi, A. V. Tomilo, D. D. Sheka, J. Fassbender, and D. Makarov, “Boundary conditions for the Neel order parameter in a chiral antiferromagnetic slab”, Phys. Rev. B 103, 134413 (2021).
[7] N. Hedrich, K. Wagner, O. V. Pylypovskyi, B. J. Shields, T. Kosub, D. D. Sheka, D. Makarov, and P. Maletinsky, “Nanoscale mechanics of antiferromagnetic domain walls”, Nature Physics (2021). https://doi.org/10.1038/s41567-020-01157-0.

Keywords: antiferromagnetic spintronics; magnetoelectric effect

  • Invited lecture (Conferences) (Online presentation)
    school in the frame of the COST Action MAGNETOFON – “Ultrafast opto-magneto-electronics for non-dissipative information technology” (https://magnetofon.science.ru.nl), 05.-08.10.2021, Samobor, Croatia

Permalink: https://www.hzdr.de/publications/Publ-32970
Publ.-Id: 32970


Designing chiral magnetic responses by tailoring geometry of thin films: curvilinear ferro- and antiferromagnets

Makarov, D.

Conventionally, tailoring of the Dzyaloshinskii-Moriya interaction (DMI) is done by optimizing materials, either doping a bulk single crystal or adjusting interface properties of thin films and multilayers. A viable alternative to the conventional material screening approach can be the exploration of the interplay between the sample geometry and topology of the order parameter. The research field in magnetism, which is dealing with the study of the impact of geometrical curvature on magnetic responses of curved 1D wires and 2D shells is known as curvilinear magnetism [1-3]. The lack of the inversion symmetry and the emergence of a curvature induced effective anisotropy and DMI stemming from the exchange interaction [4,5] are characteristic of curved surfaces, leading to curvature-driven magnetochiral effects. Volkov et al. has proven that the exchange-driven chiral effects in curvilinear ferromagnets are experimental observables [6] and can be used to realize nanostructures with tunable magnetochiral properties from standard magnetic materials.
A counterpart of the intrinsic DMI for the case of curvilinear magnets is the mesoscale Dzyaloshinskii-Moriya interaction, which is a result of the interplay between the intrinsic (spin-orbit-driven) and extrinsic (curvature-driven) DMI terms [7]. The mesoscale DMI governs the magnetochiral properties of any curvilinear ferromagnetic nanosystem and depends both on the material and geometrical parameters. Its strength and orientation can be tailored by properly choosing the geometry, which allows stabilizing distinct magnetic chiral textures including skyrmion and skyrmionium states as well as skyrmion lattices [8-10]. Interestingly, skyrmion states can be formed in a material even without an intrinsic DMI [8,10]. Very recently, Sheka et al. discovered a novel non-local chiral symmetry breaking effect, which does not exist in planar thin film magnets: it is essentially non-local and manifests itself even in static spin textures living in curvilinear magnetic nanoshells [5].
The field of curvilinear magnetism was recently extended towards curvilinear antiferromagnets. Pylypovskyi et al. demonstrated that intrinsically achiral one-dimensional curvilinear antiferromagnet behaves as a chiral helimagnet with geometrically tunable DMI, orientation of the Neel vector and the helimagnetic phase transition [11,12]. This positions curvilinear antiferromagnets as a novel platform for the realization of geometrically tunable chiral antiferromagnets for antiferromagnetic spinorbitronics.

[1] R. Streubel et al., J. Phys. D: Appl. Phys. 49 (2016), 363001.
[2] D. Sander et al., J. Phys. D: Appl. Phys. 50 (2017), 363001.
[3] E. Vedmedenko et al., J. Phys. D: Appl. Phys. 53 (2020), 453001.
[4] Y. Gaididei et al., Phys. Rev. Lett. 112 (2014), 257203.
[5] D. Sheka et al., Communications Physics 3 (2020), 128.
[6] O. Volkov et al., Phys. Rev. Lett. 123 (2019), 077201.
[7] O. Volkov et al., Scientific Reports 8 (2018), 866.
[8] V. Kravchuk et al., Phys. Rev. B 94 (2016), 144402.
[9] V. Kravchuk et al., Phys. Rev. Lett. 120 (2018), 067201.
[10] O. Pylypovskyi et al., Phys. Rev. Appl. 10 (2018), 064057.
[11] O. Pylypovskyi et al., Nano Letters 20 (2020), 8157.
[12] O. Pylypovskyi et al., Appl. Phys. Lett. 118 (2021), 182405.

Keywords: flexible magnetic field sensors; curvilinear magnetism

  • Invited lecture (Conferences) (Online presentation)
    IEEE Trends in Magnetism, 06.-10.09.2021, Palermo, Italy

Permalink: https://www.hzdr.de/publications/Publ-32968
Publ.-Id: 32968


Nanomagnetism and spintronics of Cr2O3 magnetoelectric antiferromagnets

Makarov, D.

Thin film antiferromagnets (AF) have potential to revolutionize spintronics due to their inherently magnetic-field stable magnetic order and high-frequency operation. To explore their application potential, it is necessary to understand modifications of the magnetic properties and magnetoelectric responses of AF thin films with respect to their bulk counterparts. Considering grainy morphology of thin films, questions regarding the change of the intergranular exchange, criticality behavior and switching of the order parameter need to be addressed.
Our approach is based on the electron transport characterization of magnetic responses of thin film antiferromagnets [1-4]. This task is difficult as minute uncompensated surface magnetization of antiferromagnets needs to be detected, which imposes strict requirements to the sensitivity of the method. We will outline our developments of zero-offset anomalous Hall magnetometry [1] applied to study the physics of conventional metallic IrMn and insulating magnetoelectric Cr2O3 antiferromagnets. To build a reliable description of the material properties, the analysis of the transport data is backed up by structural characterization and real space imaging of AF domain patterns using NV microscopy [2,5]. Based on this unique and novel combination, we for the first time observe the formation of nanoscale antiferromagnetic domains in thin films of Chromia (Cr2O3) across its ordering temperature at ~300 K. Our quantitative results yield a detailed understanding of the domain formation process in Cr2O3 and allow us to determine the efficiency of inter-granular magnetic exchange coupling [5]. This coupling strength has proven decisive in the decades long development of ferromagnetic memory media and will be of equal importance for future antiferromagnetic spintronics technologies, for which we here present a powerful new development tool.
The fundamental understanding of the magnetic microstructure of magnetoelectric α-Cr2O3 thin films and the possibility to read-out its antiferromagnetic order parameter all-electrically enabled the entirely new recording concept where a magnetoelectric memory cell can be addressed without using a ferromagnet. With this approach, we opened an appealing topic of purely antiferromagnetic magnetoelectric random access memory (AF-MERAM) [2].
By exploring the interaction of antiferrmagnetic domain walls with morphological structures prepared on the surface of Cr2O3 single crystals, we access the nanoscale mechanics of AF domain walls. We propose to employ nanoscale patterns as engineered pinning centers for AF domain walls,
where binary information is encoded by the direction of the Neel vector. Our results bear significant potential for technological exploitation be it in the form of the proposed antiferromagnetic memory devices, or ultimately for the realisation of DW logic using antiferromagnets.
These recent developments on the fabrication and characterization of Cr2O3-based functional elements will be discussed in this presentation.
REFERENCES
[1] T. Kosub, M. Kopte, F. Radu, O. G. Schmidt, D. Makarov, “All-Electric access to the Magnetic-Field-Invariant Magnetization of Antiferromagnets”, Phys. Rev. Lett. 115, 097201 (2015).
[2] T. Kosub, M. Kopte, R. Hühne, P. Appel, B. Shields, P. Maletinsky, R. Hübner, M. O. Liedke, J. Fassbender, O. G. Schmidt, and D. Makarov, “Purely antiferromagnetic magnetoelectric random access memory”, Nature Communications 8, 13985 (2017).
[3] R. Schlitz, T. Kosub, A. Thomas, S. Fabretti, K. Nielsch, D. Makarov, and S. T. B. Goennenwein, “Evolution of the spin hall magnetoresistance in Cr2O3/Pt bilayers close to the Neel temperature”, Appl. Phys. Lett. 112, 132401 (2018).
[4] P. Muduli, R. Schlitz, T. Kosub, R. Hübner, A. Erbe, D. Makarov, and S. T. B. Goennenwein, “Local and nonlocal spin Seebeck effect in lateral Pt-Cr2O3-Pt devices at low temperatures”, Appl. Phys. Lett. Materials 9, 021122 (2021).
[5] P. Appel, B. J. Shields, T. Kosub, R. Hübner, J. Fassbender, D. Makarov, and P. Maletinsky, “Nanomagnetism of magnetoelectric granular thin film antiferromagnets”, Nano Letters 19, 1682 (2019).
[6] O. V. Pylypovskyi, A. V. Tomilo, D. D. Sheka, J. Fassbender, and D. Makarov, “Boundary conditions for the Neel order parameter in a chiral antiferromagnetic slab”, Phys. Rev. B 103, 134413 (2021).
[7] N. Hedrich, K. Wagner, O. V. Pylypovskyi, B. J. Shields, T. Kosub, D. D. Sheka, D. Makarov, and P. Maletinsky, “Nanoscale mechanics of antiferromagnetic domain walls”, Nature Physics (2021). https://doi.org/10.1038/s41567-020-01157-0.

Keywords: antiferromagnetic spintronics

  • Invited lecture (Conferences) (Online presentation)
    2021 IEEE 11th International Conference on "Nanomaterials: Applications & Properties", 05.-11.09.2021, Odesa, Ukraine

Permalink: https://www.hzdr.de/publications/Publ-32967
Publ.-Id: 32967


Organische Synthese einer potenten Leitverbindung zur Entwicklung neuer Radioliganden für die molekulare Bildgebung der mutierten Form der Isocitrat-Dehydrogenase 1 im Gehirn mittels Positronen-Emissions-Tomographie

Linke, J.

Organische Synthese einer potenten Leitverbindung zur Entwicklung neuer Radioliganden für die molekulare Bildgebung der mutierten Form der Isocitrat-Dehydrogenase 1 im Gehirn mittels Positronen-Emissions-Tomographie

Keywords: Isocitrat-Dehydrogenase 1; mIDH1; Ligand; PET; molekulare Bildgebung

  • Master thesis
    Universität Leipzig, 2021
    Mentor: Dr. Rodrigo Teodoro, Dr. Matthias Scheunemann
    80 Seiten

Permalink: https://www.hzdr.de/publications/Publ-32960
Publ.-Id: 32960


Stretchable Thin Film Mechanical Strain Gated Switches and Logic Gate Functions Based on a Soft Tunneling Barrier

Chae, S.; Jin Choi, W.; Fotev, I.; Bittrich, E.; Uhlmann, P.; Schubert, M.; Makarov, D.; Wagner, J.; Pashkin, O.; Fery, A.

Mechanical strain gated switches are cornerstone components of material embedded circuits that perform logic operations without using conventional electronics. This technology requires a single material system to exhibit three distinct functionalities: strain-invariant conductivity and an increase or decrease of conductivity upon mechanical deformation. Herein, we demonstrate mechanical strain-gated electric switches based on a thin-film architecture that features an insulator-to-conductor transition when mechanically stretched. The conductivity changes by nine orders of magnitude over a wide range of tunable working strains (as high as 130%). Our approach relies on a nanometer-scale sandwiched bi-layer Au thin film with an ultrathin polydimethylsiloxane elastomeric barrier layer applied strain alters the electron tunneling currents through the barrier. Mechanical-force-controlled electric logic circuits are achieved by realizing strain-controlled basic (AND and OR) and universal (NAND and NOR) logic gates in a single system. The proposed material system can be used to fabricate material-embedded logics of arbitrary complexity for wide range of applications including soft robotics, wearable/implantable electronics, human machine interface and internet of things.

Keywords: Strain gated electric switch; logic gates; tunneling; stretchable circuit; thin film

Related publications

Downloads:

  • Secondary publication expected from 12.10.2022

Permalink: https://www.hzdr.de/publications/Publ-32957
Publ.-Id: 32957


Numerical Investigation of Degasification in an Electrocoagulation Reactor

Höhne, T.; Farhikhteh Asl, V.; Ople Villacorte, L.; Herskind, M.; Momeni, M.; Al-Fayyad, D.; Taș-Koehler, S.; Lerch, A.

In order to enhance retention of particulate and colloidal (organic) matter, chemical coagulation (CC) is often used prior to pressure driven membrane filtration. Electrocoagulation (EC) is an alternative to CC usually carried out in an electrochemical reactor consisting of an electrolytic cell containing at least one anode (sacrificial) and one cathode. The EC combined with a membrane filtration to a hybrid membrane system may be a potential possibility for environmental problems dealing with drinking water treatment, water reuse and rational waste management. In this study, an EC reactor with spiral electrodes was investigated numerically, focusing on modelling with a given design/geometry, configuration and boundary conditions. Two-phase flow interactions between water (liquid) and hydrogen (gas) were modelled via computational fluid dynamics (CFD). Different flow rates (Q=1-1000 l/h) through two batches of the watering stage (Case 1-3) and the degassing stage (Case 4-6) were simulated. Degassing the feed of the membrane system is of high importance in order to achieve stable operation. The results provided information about flow characteristics such as sufficient retention time, water circulation by velocity vectors, undesirable gas penetration into the water inlet channel, gas holdup during watering and degassing, and finally the optimal period for the degasification. The results showed that as the water velocity increases, retention time decreases. The results also showed that thirty seconds seemed the optimal time with the gas holdup of 0.020%, 0.028%, and 0.027% respectively for Case 4, Case 5, and Case 6. Another finding is that the consideration for the most abundant gas holdup for the typical BC was the smallest ratio of water flow to gas flow.

Keywords: hybrid membrane process; electrocoagulation; CFD; hydrogen bubble; degassing optimization

Permalink: https://www.hzdr.de/publications/Publ-32954
Publ.-Id: 32954


An updated strategic research agenda for the integration of radioecology in the european radiation protection research

Gilbin, R.; Arnold, T.; Beresford, N. A.; Berthomieu, C.; Brown, J. E.; de With, G.; Horemans, N.; Madruga, M. J.; Masson, O.; Merroun, M.; Michalik, B.; Muikku, M.; O’Toole, S.; Mrdakovic Popic, J.; Nogueira, P.; Real, A.; Sachs, S.; Salbu, B.; Stark, K.; Steiner, M.; Sweek, L.; Vandenhove, H.; Vidal, M.; Vives I. Batlle, J.

The ALLIANCE Strategic Research Agenda (SRA) for radioecology is a living document that defines a long-term vision (20 years) of the needs for, and implementation of, research in radioecology in Europe. The initial SRA, published in 2012, included consultation with a wide range of stakeholders (Hinton et al., 2013). This revised version is an update of the research strategy for identified research challenges, and includes a strategy to maintain and develop the associated required capacities for workforce (education and training) and research infrastructures and capabilities. Beyond radioecology, this SRA update constitutes a contribution to the implementation of a Joint Roadmap for radiation protection research in Europe (CONCERT, 2019a). This roadmap, established under the H2020 European Joint Programme CONCERT, provides a common and shared vision for radiation protection research, priority areas and strategic objectives for collaboration within a European radiation protection research programme to 2030 and beyond. Considering the advances made since the first SRA, this updated version presents research challenges and priorities including identified scientific issues that, when successfully resolved, have the potential to impact substantially and strengthen the system and/or practice of the overall radiation protection (game changers) in radioecology with regard to their integration into the global vision of European research in radiation protection. An additional aim of this paper is to encourage contribution from research communities, end users, decision makers and other stakeholders in the evaluation, further advancement and accomplishment of the identified priorities.

Keywords: Strategic Research Agenda for radioecology; Environmental exposure to radionuclides; Radiation protection of the environment; Integration of radiation protection research; Education and training; Infrastructures

Permalink: https://www.hzdr.de/publications/Publ-32953
Publ.-Id: 32953


Large magnetic entropy change in Nd2In near the boiling temperature of natural gas

Liu, W.; Scheibel, F.; Gottschall, T.; Bykov, E.; Dirba, I.; Skokov, K.; Gutfleisch, O.

Natural gas is useful for the transition from traditional fossil fuels to renewable energies. The consumption of liquid natural gas has been rising, and the demand is predicted to double by 2040. In this context, magnetocaloric gas liquefaction, as an emerging and energy-saving technology, could be an alternative to the traditional gas-compression refrigeration. In this work, we report a large magnetic entropy change of 7.42 J/kg K under a magnetic field change of 2 T in Nd2In at 109 K, which is near the boiling temperature of natural gas of 112 K. The maximum adiabatic temperature change reaches 1.13K under a magnetic field change of 1.95 T and is fully reversible. The magnetic phase transition is confirmed to be of the first-order type with the negligible thermal hysteresis. Further investigations on the thermal expansion and the magnetostriction reveal that the magnetic transition undergoes two stages with a negligible volume change. The longitudinal strain increases with magnetic fields and then decreases. These interesting properties are useful for the practical design of a magnetocaloric natural gas liquefaction system and for the fundamental understanding of the phase transitions in other RE2In intermetallics.

Permalink: https://www.hzdr.de/publications/Publ-32952
Publ.-Id: 32952


Influence of microstructure on the application of Ni-Mn-In Heusler compounds for multicaloric cooling using magnetic field and uniaxial stress

Pfeuffer, L.; Gracia-Condal, A.; Gottschall, T.; Koch, D.; Faske, T.; Bruder, E.; Lemke, J.; Taubel, A.; Ener, S.; Scheibel, F.; Durst, K.; Skokov, K. P.; Manosa, L.; Planes, A.; Gutfleisch, O.

Novel multicaloric cooling utilizing the giant caloric response of Ni-Mn-based metamagnetic shape- memory alloys to different external stimuli such as magnetic field, uniaxial stress and hydrostatic pressure is a promising candidate for energy-efficient and environmentally-friendly refrigeration. However, the role of microstructure when several external fields are applied simultaneously or sequentially has been scarcely discussed in literature. Here, we synthesized ternary Ni-Mn-In alloys by suction casting and arc melting and analyzed the microstructural influence on the response to magnetic fields and uniaxial stress. By combining SEM-EBSD and stress-strain data, a significant effect of texture on the stress- induced martensitic transformation is revealed. It is shown that a <001> texture can strongly reduce the critical transformation stresses. The effect of grain size on the material failure is demonstrated and its influence on the magnetic-field-induced transformation dynamics is investigated. Temperature-stress and temperature-magnetic field phase diagrams are established and single caloric performances are characterized in terms of ΔsT and ΔTad. The cyclic ΔTad values are compared to the ones achieved in the multicaloric exploiting-hysteresis cycle. It turns out that a suction-cast microstructure and the combination of both stimuli enables outstanding caloric effects in moderate external fields which can significantly exceed the single caloric performances. In particular for Ni-Mn-In, the maximum cyclic effect in magnetic fields of 1.9 T is increased by more than 200 % to -4.1 K when a moderate sequential stress of 55 MPa is applied. Our results illustrate the crucial role of microstructure for multicaloric cooling using Ni-Mn- based metamagnetic shape-memory alloys.

Permalink: https://www.hzdr.de/publications/Publ-32951
Publ.-Id: 32951


Evaluation of the effective temperature change in Gd-based composite wires assessed by static and pulsed-field magnetic measurements

Beyer, L.; Weise, B.; Freudenberger, J.; Hufenbach, J. K.; Gottschall, T.; Krautz, M.

Gd cladded in a seamless 316L austenitic steel tube has been swaged into wires by the powder-in-tube (PIT) technology, resulting in an outer diameter of 1 mm, a wall thickness of approx. 100 μm and a filling factor of around 62 vol%. Such wires provide an advantageous geometry for heat exchangers and have the benefit to protect the Gadolinium, i.e. from corrosion when being in contact with a heat transfer fluid. The magnetocaloric composite has been studied by static and pulsed magnetic-field measurements in order to evaluate the performance of Gd as a core material. By the analysis of magnetization and heat capacity data, the influences of deformation-induced defects on Gadolinium are presented. The subsequent heat treatment at 773 K for 1 h in Ar atmosphere allowed restoring the magnetic properties of the wire after deformation. Data of the pulsed magnetic-field measurements on the Gd-filled PIT-wires and a Gd–core separated from the jacket are presented, with an achievable temperature change of 1.2 K for the wire and 5.2 K for the Gd in 2 T, respectively. A comparison to previously studied La(Fe, Co, Si)13-filled composite wires is included. It indicates that performance losses due to the passive matrix material cannot be overcome only by an increased adiabatic temperature change of the core material, but instead the wire components need to be chosen regarding an optimized heat capacity ratio, as well.

Permalink: https://www.hzdr.de/publications/Publ-32950
Publ.-Id: 32950


Correlated effects of fluorine and hydrogen in fluorinated tin oxide (FTO) transparent electrodes deposited by sputtering at room temperature

Morán-Pedroso, M.; Gago, R.; Julin, J. A.; Salas-Colera, E.; Jimenez, I.; de Andrés, A.; Prieto, C.

The optical and electrical properties of fluorinated tin oxide (FTO) films deposited at room temperature by sputtering have been investigated varying the fluorine content and the hydrogen atmosphere. The complex behavior of the obtained films is disclosed using a wide set of characterization techniques that reveals the combined effects of these two parameters on the generated defects. These defects control the electrical transport (carrier density, mobility and conductivity), the optical properties (band gap and defects-related absorption and photoluminescence) and finally promote the amorphization of the samples. H₂ in the sputtering gas does not modify the H content in the films but induces the partial reduction of tin (from Sn4+ to Sn2+) and the consequent generation of oxygen vacancies with shallow energy levels close to the valence band. A variation of up to four orders of magnitude in electrical conductivity is reported in samples with the appropriate fluorine doping and hydrogen fraction in the sputtering gas, maintaining excellent optical transparency. Optimized room temperature grown electrodes reach sheet resistance ~20 Ω/□ and transparency >90%. This room temperature deposition process enables film preparation on flexible organic substrates, such as polyethylene terephthalate (PET), with identical performance of doubtless interest in flexible and large scale electronics.

Keywords: Transparent conductive materials; Fluorinated tin oxide; Room temperature film preparation

Permalink: https://www.hzdr.de/publications/Publ-32947
Publ.-Id: 32947


UDV methods for characterizing flows in liquid metal batteries

Cheng, J.; Wang, B.; Mohammad, I.; Horstmann, G. M.; Kelley, D.

We present ultrasound measurements from a laboratory model of a liquid metal battery (LMB). Two major flow
drivers interact within LMBs: thermal gradients due to the presence of internal heating, and electrovortex flow
(EVF) driven by diverging current densities. The product of these interactions remains poorly characterized. We
approach this problem with ultrasonic Doppler velocimetry (UDV) combined with a laboratory model of an LMB
fluid layer. Using ultrasound probes placed around a liquid gallium vessel, we elucidate typical velocities, flow
structures, and flow statistics in a representative volume of the flow field. UDV measurements reveal that pure
convection takes the form of the recently-discovered ‘jump rope vortex,’ with a characteristic frequency visible in
velocity statistics. They also indicate that EVF goes through stable, unstable, and oscillatory flow regimes. In
progress is an approach for training physics-informed neural networks (PINNs) on UDV data, allowing us to
reconstruct flow in regions where no probe measurements have taken place by leveraging the equations of motion.

  • Contribution to proceedings
    13th International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering (ISUD 2021), 13.-15.06.2021, Zürich, Schweiz

Permalink: https://www.hzdr.de/publications/Publ-32944
Publ.-Id: 32944


Highlight selection of radiochemistry and radiopharmacy developments by editorial board

Alves, F.; Antunes, I.; Cazzola, E.; Cleeren, F.; Cornelissen, B.; Denkova, A.; Engle, J.; Faivre-Chauvet, A.; Gillings, N.; Hendrikx, J.; Jalilian, A.; van der Meulen, N.; Mikolajczak, R.; Neels, O.; Pillai, M.; Reilly, R.; Rubow, S.; Seimbille, Y.; Spreckelmeyer, S.; Szymanski, W.; Taddei, C.

Background: The Editorial Board of EJNMMI Radiopharmacy and Chemistry releases a biyearly highlight commentary to update the readership on trends in the field of radiopharmaceutical development.
Results: This commentary of highlights has resulted in 21 different topics selected by each member of the Editorial Board addressing a variety of aspects ranging from novel radiochemistry to first in man application of novel radiopharmaceuticals. Also the first contribution in relation to MRI-agents is included.
Conclusion: Trends in (radio)chemistry and radiopharmacy are highlighted demonstrating the progress in the research field being the scope of EJNMMI Radiopharmacy and Chemistry.

Permalink: https://www.hzdr.de/publications/Publ-32943
Publ.-Id: 32943


Hydrodynamic and efficiency data pertaining to an air-water column mockup (of 0.8 m internal diameter) equipped with sieve trays

Vishwakarma, V.; Marchini, S.; Schleicher, E.; Schubert, M.; Hampel, U.
DataCollector: Vishwakarma, Vineet; DataCollector: Marchini, Sara; RelatedPerson: Schleicher, Eckhard; ContactPerson: Schubert, Markus; Supervisor: Hampel, Uwe

The hydrodynamic data including effective froth height, liquid holdup and tracer flow and patterns related to an operational sieve tray inside a 0.8 m diameter air-water column simulator are provided here. These data were obtained via an advanced multiplex flow profiler at several gas and liquid loadings. The generated data were examined for predicting the tray efficiency using mathematical models. For model validation, the stripping of isobutyl acetate from the aqueous solution over the tray was employed, and the liquid samples at several tray locations were analyzed via UV spectroscopy. The resulting efficiencies and related information are provided here, too. All raw data files, data processing scripts and supporting information with proper indexing and sequencing are uploaded. All these data are intended for non-commercial use only.

Keywords: Column tray; two-phase crossflow; 3D liquid holdup; effective froth height; tracer-response analysis; tray efficiency calculations

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-07-21
    DOI: 10.14278/rodare.1071

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Permalink: https://www.hzdr.de/publications/Publ-32942
Publ.-Id: 32942


Curium(III) speciation in the presence of microbial cell wall components

Moll, H.; Barkleit, A.; Frost, L.; Raff, J.

Trivalent actinides such as Cm(III) are able to strongly interact with microbes and especially with bacterial cell walls. However, detailed knowledge of the influence of different cell wall components is somewhat lacking. For this investigation, we studied the formation of aqueous Cm(III) complexes with cell wall components (e.g., lipopolysaccharide, peptidoglycan, and plasma membranes) using time-resolved laser-induced fluorescence spectroscopy (TRLFS). For all systems, two specific Cm(III) complexes with the biomacromolecules were observed as a function of pH. Specifically, Cm(III) was found to bind to phosphate and carboxyl groups present in the structure of the biomacromolecules. Stability constants and luminescence parameters of the specific Cm(III) complexes were determined and are presented. The pH of the surrounding aqueous solution, the plasma membrane concentration, and proteins included in the crude plasma membrane fraction were found to significantly impact the complexation of Cm(III). The Cm(III) luminescence spectra with plasma membranes, cell wall polymers, as well as Gram-negative (Sporomusa sp. MT-2.99 and Pseudomonas fluorescens) and Gram-positive (Paenibacillus sp. MT-2.2) bacteria will be explained by linear combination fitting using the investigated components.

Keywords: curium; lipopolysaccharide; peptidoglycan; plasma membrane; bacterial cell walls; luminescence spectroscopy

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  • Secondary publication expected from 12.10.2022

Permalink: https://www.hzdr.de/publications/Publ-32941
Publ.-Id: 32941


Superconducting solenoid field measurement and optimization

Ma, S.; Arnold, A.; Ryzhov, A.; Murcek, P.; Zwartek, P.; Schaber, J.; Qian, H.; Teichert, J.; Xiang, R.

The solenoid is a significant part of an electron injector to provide a proper focusing, and preserve the beam projected emittance. A superconducting solenoid is applied for the SRF photoinjector at HZDR. The solenoid itself can degrade electron beam quality due to magnetic field imperfections like multipole components. In order to determine the field aberrations in the solenoid, we measured the superconducting solenoid magnetic field in the cryomodule. A simple and effective method is used to analyze the multipole field components, which will be presented in this paper.

Keywords: solenoid; magnetic field

  • Open Access Logo Contribution to proceedings
    12th International Particle Accelerator Conference (IPAC’21), 24.-28.05.2021, Brasília, Brazil
    Proceedings of IPAC’21: JACoW

Permalink: https://www.hzdr.de/publications/Publ-32938
Publ.-Id: 32938


Generalized Landau-Khalatnikov-Fradkin transformations for arbitrary N-point fermion correlators

Ahmadiniaz, N.; Edwards, J. P.; Nicasio, J.; Schubert, C.

We examine the nonperturbative gauge dependence of arbitrary configuration space fermion correlators in quantum electrodynamics (QED). First, we study the dressed electron propagator (allowing for emission or absorption of any number of photons along a fermion line) using the first quantized approach to quantum field theory and analyze its gauge transformation properties induced by virtual photon exchange. This is then extended to the N-point functions where we derive an exact, generalized version of the fully nonperturbative Landau-Khalatnikov-Fradkin (LKF) transformation for these correlators. We discuss some general aspects of the application in perturbation theory and investigate the structure of the LKF factor aboutD¼2dimensions

Keywords: LKFT; Worldline formalism; Non-perturbative QED

Permalink: https://www.hzdr.de/publications/Publ-32937
Publ.-Id: 32937


High-entropy carbons: From high-entropy aromatic species to single-atom catalysts for electrocatalysis

Ding, J.; Wu, D.; Zhu, J.; Rodríguez-Hernández, F.; Chen, Y.; Lu, C.; Zhou, S.; Zhang, J.; Tranca, D.; Zhuang, X.

Single-atom catalysts (SACs) have rapidly entered the field of nanomaterials and demonstrated great potential for energy devices in recent years. Of all types of SACs, porous carbon-based SACs are the most popular species because of their excellent conductivity, large specific surface area, and easily tunable heteroatom and metal components. However, most of the reported cases focus on the metal centers and their coordination environments, while they do not pay much attention to carbon precursors and carbon transformation during high-temperature treatment. In this work, we use a high-entropy aromatic molecule, azulene, for rational synthesis of azulene-enriched, sandwich-like polymer nanosheets and corresponding single-Fe-dispersed porous carbon nanosheets. The azulene-based metal-free polymer nanosheets exhibit a narrow band gap and temperature-dependent magnetism. As proof-of-concept electrocatalysts for CO2 reduction, the prepared carbon nanosheets exhibit high activity and stability. Operando X-ray absorption spectroscopy and density functional theory studies reveal the high activity of Fe-N coordination sites in the presence of 5/7-membered carbon ring-based topological defects in the carbon skeleton. Taken together, this work provides a new method of synthesizing high-entropy carbons using azulene-based high-entropy molecule as precursor and paves the way toward high-efficiency SACs with rich topological defects for energy conversion.

Keywords: High-entropy aromatic molecule; Topological defect; Single-atom catalyst; Porous carbon nanosheet; Carbon dioxide conversion

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  • Secondary publication expected from 14.07.2022

Permalink: https://www.hzdr.de/publications/Publ-32934
Publ.-Id: 32934


QE and life time of Cs2Te photocathodes on copper for SRF gun-II at HZDR

Xiang, R.; Arnold, A.; Ma, S.; Murcek, P.; Ryzhov, A.; Schaber, J.; Teichert, J.

The SRF gun-II at HZDR has been stably applied as the electron
source for high power THz radiation since 2018, generating CW beams
with bunch charges up to 300 pC at 100 kHz. It is an excellent demonstration
that SRF guns can work reliably in a high power user facility.
In order to generate higher current beam with MHz repetition rate,
Cs2Te photocathodes are required. However, in last two experiments
with Cs2Te, the Mo substrate plugs were overheated in superconducting
rf cavity. The reason is that different thermal expansion coefficient
of Mo and Cu led to a bad thermal contact between the Mo plug and
Cu holder. Thus we decided to use Cu as new substratum of Cs2Te
cathodes. In last year we prepared several Cs2Te photocathodes on Cu
plugs and improved the vacuum of cathode transfer system in order
to achieve satisfied lifetime. In this contribution, we will present the
study result of QE and life time of Cs2Te photocathodes with different
thickness.

Keywords: SRF gun; photocathode; Cs2Te

  • Open Access Logo Lecture (Conference) (Online presentation)
    DPG-Frühjahrstagung (Dortmund), 15.-19.03.2021, Dortmund, Germany

Permalink: https://www.hzdr.de/publications/Publ-32933
Publ.-Id: 32933


Observability of Coulomb-assisted quantum vacuum birefringence

Ahmadiniaz, N.; Bussmann, M.; Cowan, T.; Debus, A.; Kluge, T.; Schützhold, R.

We consider the scattering of an x-ray free-electron laser (XFEL) beam on the superposition of
a strong magnetic field $\bf{B}_{\rm ext}$ with the Coulomb field $\bf{E}_{\rm ext}$
of a nucleus with charge number $Z$. In contrast to Delbr\"uck scattering
(Coulomb field only), the magnetic field $\bf{B}_{\rm ext}$
introduces an asymmetry (i.e., polarization dependence) and renders the effective interaction volume quite
large, while the nuclear Coulomb field facilitates a significant momentum transfer $\Delta\bf k$.
For a field strength of $B_{\rm ext}=10^6 T$ (corresponding to an intensity of order $10^{22}~\rm W/cm^2$)
and an XFEL frequency of 24~keV, we find a differential cross section
$d\sigma/d\Omega\sim10^{-25}~Z^2/(\Delta{\bf k})^2$ in forward direction for one nucleus.
Thus, this effect might be observable in the near future at facilities such as the
Helmholtz International Beamline for Extreme Fields (HIBEF) at the European XFEL.

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Permalink: https://www.hzdr.de/publications/Publ-32932
Publ.-Id: 32932


Caesium deposition on GaN to obtain a photocathode for particle accelerator

Schaber, J.; Xiang, R.; Teichert, J.; Arnold, A.; Ryzhov, A.; Murcek, P.; Zwartek, P.; Ma, S.

Negative electron affinity (NEA) GaAs- and GaN-based photocathodes are used in modern night vison detectors and light emitting diodes1. GaAs semiconductors are already used as electron sources in particle accelerators and well- studied2. Like GaAs, GaN belongs to the
III-V semiconductor group with similar properties. It is assumed that GaN, like GaAs, shows enormous potential as a novel electron source for particle accelerators.

P-type GaN on different substrate material (sapphire, silicon, copper or SiC) is activated by a thin layer of caesium and illuminated by ultra-violet (UV) light at the same time. As a consequence of negative electron affinity (NEA) and photoeffect, the generated photoelectrons enter into vacuum and are collected by a copper ring anode. The resulting photocurrent is detected during the whole activation process and stopped when a maximum photocurrent is reached.
The GaN is chemical cleaned and transferred into a UHV chamber where it undergoes a thermal heat treatment at 250°C for 20 min using a halogen lamp. The aim of the thermal treatment is to remove residual adsorbed gas molecules from the sample surface.
Afterwards when the sample is back at room temperature, the thermal-cleaned GaN is activated with a thin layer of caesium. The photocurrent and the QE is observed in the following days until the QE vanishes. Then it is tested to re-activate the cathode again, meaning to thermal clean it again and to activate it with caesium once more.

By a comparison of differences in substrate material, chemical pre-cleaning, thermal heat treatment and activation parameters (e.g. caesium-flux), the photocurrent, quantum efficiency and the re-activation of the photocathode is studied. Additionally the GaN samples are examined by AFM, SEM and EDX.
From the experimental results obtained so far, it appears that GaN:Cs could be used as a photocathode in particle accelerators, but further investigations are still required and needed.

Keywords: gallium nitride; photocathode; caesium deposition; SRF Gun

  • Open Access Logo Poster (Online presentation)
    DPG-Frühjahrstagung des Fachverbandes Oberflächenphysik, 01.-04.03.2021, Hannover, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-32929
Publ.-Id: 32929


Status Report of GaN photocathode

Schaber, J.; Xiang, R.; Teichert, J.; Ryzhov, A.; Murcek, P.; Zwartek, P.; Ma, S.

The photocathodes determine the beam quality in linear accelerators and represent a key component for many accelerator projects. Free-electron lasers (FEL), synchrotron- and THz radiation sources require injector systems with high brightness electron beams.

High quantum efficiency, a long lifetime and good vacuum stability, fast response time and low thermal emittance are desirable parameters for a perfect photocathode used in accelerators. Semiconductors such as GaN and GaAs as novel materials for photocathodes are showing an enormous potential.
GaAs is a well-known material for photocathodes. After activation with caesium and oxygen, it has a high QE for visible light (red or green). An advantage of GaAs is the opportunity of the layers to emit spin-polarized electrons.
GaN is a semi-conductive material and well known for its high QE when lighted with UV light. For improving the QE only caesium for activation is required.
At the moment GaN is used for photocathode-based detectors such as photomultipliers or phototubes and for LEDs. They have characteristics of low dark current, high-speed response and high sensitivity. It is very new for application in SRF Guns. It seems to be more robust and achieves higher QE than other photocathodes [1].
Crystallinity and surface parameters define the photoemission properties. Modern analytical methods are used for identification of impurities, dislocations and characterization of the crystallinity of the semiconductors and the right cleaning treatment as well as the right caesium rating.
[1] Uchiyama, Shoichi et al. 2011. “GaN-Based Photocathodes with Extremely High Quantum Efficiency” 103511(2005):1–4.

Keywords: gallium nitride; photocathode; SRF Gun

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    High Brightness Electron beams generated from novel THermal resistant photocathodes (BETH) 3rd Collaboration Meeting, 01.03.2021, Siegen, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-32928
Publ.-Id: 32928


Mounted Single Particle Characterization for 3D Mineralogical Analysis - MSPaCMAn

Da Assuncao Godinho, J. R.; Danelon Grilo, B. L.; Hellmuth, F.; Siddique, A.

This paper demonstrates a new method to classify mineral phases in 3D images of particulate materials obtained by x-ray computed tomography. The method consists of 1) sample preparation and scanning of a particle dispersion; 2) image processing optimized towards the labelling of individual particles in the sample; 3) phase identification is done at the particle level using an interpretation of the grey-values of all voxels in a particle rather than of all voxels in the sample. The method allows minimizing the impact of typical image artefacts in the classification of voxels, i.e. beam hardening, partial volume effect, spot blurriness and cone beam. Additionally, the particle’s geometry and microstructure can be used as classification criteria besides the grey-values. The result is an increased accuracy of phase classification, reduced detection limit of phases, lower grain size to voxel size ratio that can be detected, individual particle statistics can be measured instead of only bulk statistics. Consequently, the method broadens the applicability of 3D imaging techniques for particle analysis at low particle size to voxel size ratio, which is typically limited by unreliable phase classification that leads to inaccurate quantification. This opens the possibility for 3D semi-automated mineralogy.

Related publications

Permalink: https://www.hzdr.de/publications/Publ-32924
Publ.-Id: 32924


Two Examples for AI Communities

Juckeland, G.; Steinbach, P.

This short talk presents two approaches for building AI communities in the Dresden area. First the top down approach of Helmholtz AI, where HZDR is one of six hubs of consultants to assist and train scientists. Second with the Machine Learning Community (MLC) Dresden a bottom up approach of practitioners just sharing experience and information in regular seminars and other asynchronous communication channels.

Keywords: Helmholtz AI

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    Kick-Off of Scientific Area Network “Dimensions of Artificial Intelligence”, 16.07.2021, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-32923
Publ.-Id: 32923


Operational experience of photocathodes for HZDR SRF gun

Xiang, R.; Arnold, A.; Ma, S.; Murcek, P.; Teichert, J.; Schaber, J.; Zwartek, P.

The SRF gun-II at HZDR has been stably applied as the electron source for high power THz radiation since 2018, generating CW beams with bunch charges up to 300 pC at 100 kHz. It is an excellent demonstration that SRF guns can work reliably in a high power user facility.
As well known, that the quality of the photocathodes is critical for the stability and reliability of the gun operation. In last years, thank to the successful ps UV laser cleaning, Mg photocathodes were successfully used for gun operation at kHz repitition rate.
In order to satisfy user request of MHz operation, Cs2Te is still in demand. However, the Mo plugs were overheated in superconducting rf cavity due to thermal contact problem, and SRF Gun-II faced twice serious contamination in 2017. The Cs2Te could not be used in gun untill Cu is adopted in stead of Mo as new substratum. Up to now three Cs2Te cathodes on Cu plugs have been applied in the Gun-II.
In this contribution, we will present the operational aspect of the photocathodes for SRF gun, and discuss the possible improvement in the future application.

Keywords: SRF gun; photocathode

  • Open Access Logo Poster (Online presentation)
    2021 International Conference RF Superconductivity, 28.06.-02.07.2021, East Lansing, USA

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Permalink: https://www.hzdr.de/publications/Publ-32922
Publ.-Id: 32922


Review of superconducting radiofrequency gun

Xiang, R.

The success of proposed high power free-electron lasers (FELs) and energy recovery linac (ERL) largely depends on the development of the electron source, which requires the best beam quality and CW operation. An elegant way to realize both high brilliance and high current is to com-bine the high beam quality of the normal conducting radio frequency photoinjector with the quick developing superconducting radio frequency technology, to build superconducting rf photoinjectors (SRF guns).
In last decade, several SRF gun programs based on dif-ferent approaches have achieved promising progress, even succeeded in routine operation at BNL and HZDR. In the near future SRF guns are expected to play an im-portant role for hard X-ray FEL facilities. In this contribu-tion, we will review the design concepts, parameters, and status of the major SRF gun projects.

Keywords: SRF gun

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    12th International Particle Accelerator Conference (IPAC’21), 24.-28.05.2021, virtual format, Brazil
  • Open Access Logo Contribution to proceedings
    12th International Particle Accelerator Conference - IPAC’21, 24.-28.05.2021, virtual format, Brazil
    Proceedings of IPAC’21: JACoW
    DOI: 10.18429/JACoW-IPAC2021-WEXC03

Permalink: https://www.hzdr.de/publications/Publ-32921
Publ.-Id: 32921


Solving overheating of Cs2Te cathodes in the ELBE SRF gun

Arnold, A.

In 2014, the second-generation of the ELBE SRF gun replaced its predecessor, which had been in operation since 2007. In the first two years, copper and magnesium cathodes were initially used without any discernible problems. However, after switching to Cs2Te in 2017, it was found that the layers of two cathodes evaporated within a few days during RF operation in the Gun. Since this was never observed in Gun I, an extensive root cause search was conducted using a dedicated cathode test setup. The findings pointed to loose thermal contact between the cathode plug and the cathode body and ultimately resulted in a change
of the used cathode substrate from molybdenum to copper. Although this was accompanied by a lower quantum efficiency of about 5% after preparation, it stabilized to 1-2% during beam operation in the SRF gun. As of May 2020, three of these cathodes have now been successfully used for THz user beam time and a total charge of 26 C has been extracted. Together with the electrons still produced by Mg cathodes in 2019/2020, a total of 217 user shifts could be served and 2600h hours of beam time were delivered. This demonstrates the reliability of CW SRF in combination with normal conducting cathode and is so far unique in the world. During the talk, the reason for overheating, the preparation on Cu substrate as well as experiences from the past two years of user beam operation will be presented in detail.

Keywords: SRF gun; SRF; superconducting; radio frequency; ELBE

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    7th MT meeting (virtuell), 01.-03.02.2021, Online, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-32920
Publ.-Id: 32920


RF Experience from 6 Years of ELBE SRF-Gun II Operation

Arnold, A.; Lu, P.; Ma, S.; Murcek, P.; Ryzhov, A.; Schaber, J.; Teichert, J.; Xiang, R.; Ciovati, G.; Kneisel, P.; Vennekate, H.

At the electron accelerator for beams with high bril-liance and low emittance (ELBE), the second version of a superconducting radio-frequency (SRF) pho-toinjector was brought into operation in 2014. After a period of commissioning, a gradual transfer to routine operation took place in 2017 and 2018, so that now more than 3400h of user beam have already been gen-erated since 2019. During this time, a total of 20 cath-odes (2 Cu, 12 Mg, 6 Cs2Te) were used, but no serious cavity degradation was observed. In this paper, we summarize the operational experience of the last 6 years of SRF gun operation, with special emphasis on main RF properties of the gun cavity.

Keywords: SRF gun; SRF; superconducting; radio frequency; ELBE

  • Open Access Logo Poster (Online presentation)
    2021 International Conference on RF Superconductivity (SRF'21), 28.06.-02.07.2021, East Lansing, Michican, USA

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Permalink: https://www.hzdr.de/publications/Publ-32919
Publ.-Id: 32919


Unusual field-induced spin reorientation in FeCr2S4: Field tuning of the Jahn-Teller state

Prodan, L.; Yasin, S.; Jesche, A.; Deisenhofer, J.; Krug Von Nidda, H.-A.; Mayr, F.; Zherlitsyn, S.; Wosnitza, J.; Loidl, A.; Tsurkan, V.

The multiferroic spinel FeCr2S4 is a benchmark material for exploring the competition of spin-orbit (SO) and Jahn-Teller (JT) coupling. Our magnetic and thermodynamic studies of stoichiometric single-crystalline samples evidence a magnetic-field-induced spin-reorientation transition in the cooperative JT state below 10 K. At 2 K, at a critical magnetic field of 4.5 T, the magnetization measured along the hard magnetization axis [111] manifests a jump to the fully saturated state accompanied by a steplike decrease of the sound velocity and an abrupt increase of the magnetostriction. All these quantities reveal a hysteretic behavior pointing towards a first-order magnetostructural transformation. Below the JT transition, the specific heat shows a complex behavior upon the application of magnetic fields depending on the crystallographic directions. The observed reduction by 20% of the magnetic anisotropy below the JT transition is attributed to the competition of the SO and JT interactions tuned by external magnetic fields. The concomitant change of the structural symmetry results in a change of the splitting of the lowest levels of the 5E doublet of the tetrahedrally coordinated Fe2+ ions.

Permalink: https://www.hzdr.de/publications/Publ-32915
Publ.-Id: 32915


Experimental Data: Endocytosis is a means of uranium(VI) uptake in tobacco (Nicotiana tabacum) BY-2 cells

John, W.; Lückel, B.; Matschiavelli, N.; Hübner, R.; Matschi, S.; Hoehenwarter, W.; Sachs, S.

The interaction of tobacco (Nicotiana tabacum) BY-2 cells with uranyl(VI) nitrate in phosphate-deficient medium was investigated. The hypothesis was that endocytosis is a means of uranium uptake in these cells. Analysis was in the form of physiological studies (growth and viability), electron microscopy, proteomics and biochemical studies.

Keywords: uranium; tobacco BY-2; endocytosis; radionuclide interaction; TEM-EDX; proteomics

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2022-01-01
    DOI: 10.14278/rodare.1046
    License: CC-BY-4.0
    Embargo: 01.01.2022

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Permalink: https://www.hzdr.de/publications/Publ-32913
Publ.-Id: 32913


Intra-unitcell cluster-cluster magnetic compensation and large exchange bias in cubic alloys

Giri, B.; Sahni, B.; Salazar Mejia, C.; Chattopadhyay, S.; Zeitler, U.; Alam, A.; Nayak, A. K.

Composite quantum materials are the ideal examples of multifunctional systems, which simultaneously host more than one novel quantum phenomenon in physics. Here, we present a combined theoretical and experimental study to demonstrate the presence of an extremely large exchange bias in the range 0.8–2.7 T and a fully compensated magnetic state (FCF) in a special type of Pt and Ni-doped Mn3In cubic alloy. Here, oppositely aligned uncompensated moments in two different atomic clusters sum up to zero, which are responsible for the FCF state. Our density functional theory (DFT) calculations show the existence of several possible ferromagnetic configurations with the FCF as the energetically most stable one. The microscopic origin of the large exchange bias can be interpreted in terms of the exchange interaction between the FCF background and the uncompensated ferrimagnetic clusters stabilized due to its negligible energy difference with respect to the FCF phase. We utilize pulsed magnetic field up to 60 T and 30 T static-field magnetization measurements to confirm the intrinsic nature of exchange bias in our system. Finally, our Hall effect measurements demonstrate the importance of uncompensated noncoplanar interfacial moments for the realization of large EB. The present finding of gigantic exchange bias in a unique compensated ferrimagnetic system opens up a direction for the design of novel quantum phenomena for the technological applications.

Permalink: https://www.hzdr.de/publications/Publ-32912
Publ.-Id: 32912


A contribution to understanding the flotation behavior of lithium metal oxides and spheroidized graphite for lithium-ion battery recycling

Vanderbruggen, A.; Sygusch, J.; Rudolph, M.; Serna-Guerrero, R.

The treatment of end-of-life lithium-ion batteries (LIBs) using froth flotation has recently gained interest as a method to separate valuable lithium transition-metal oxides (LMOs) and graphite particles from the so-called “black mass” mixture. However, the flotation mechanisms of the cathode active particles have not been properly discussed so far, likely since they are generally accepted to be hydrophilic and are thus expected to remain suspended in the bulk phase and recovered in the underflow. Nevertheless, the froth phase products reported in the literature often contain more than 10% LMOs. This results in losses of cathode materials, while hampering the quality of the recovered anode components. As graphite is one of the main materials used for anode manufacturing, being categorized as a critical raw material, its recovery plays an essential role in the electric vehicle revolution.

This work provides the first fundamental study on the flotation mechanisms of the fine particulate black mass components, with the aim of properly identifying the challenges to overcome in order to drive selectivity in froth flotation separation. A series of analysis using model black mass were carried out to circumvent the influence of residual hydrophobic binder found in LIB waste. Studies of wettability with captive bubble and Washburn capillary rise methods show contact angles for LMOs varying from 14° to 52.6° depending on the technique used. Using a bubble-particle attachment set-up it was found that LMO particles can attach to air bubbles spontaneously and in measurable quantities, contrary to the commonly assumed hydrophilic character of cathode active particles. It was also observed that the typically used oil-based collectors (e.g., Escaid 110) interact with both spheroidized graphite and lithium metal oxides, increasing their hydrophobicity and promoting agglomeration. Finally, the particle agglomeration of black mass components provides another flotation mechanism for LMOs through entrapment.

Keywords: Black mass; Lithium ion batteries; Lithium transition metal oxides; Spheroidized graphite; Recycling; Froth flotation

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  • Secondary publication expected from 05.11.2022

Permalink: https://www.hzdr.de/publications/Publ-32908
Publ.-Id: 32908


Microstructure and texture development during hot-compression of Ti5321

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

The microstructure and texture development of the metastable β‑titanium alloy Ti5321 during hot-compression were investigated by electron backscatter diffraction. Above the β-transus temperature, deformation is accompanied by continuous dynamic recrystallization leading to immediate steady state flow. The deformation below the β-transus temperature is significantly affected by α-precipitation. Dynamic globularization of the α-lamellae leads to flow softening. During hot-compression, parallel to the compression axis a 〈100〉〈111〉double fiber texture develops. With increasing temperature the intensity of 〈100〉increases, while that of <111> decreases. At all temperatures <100> is dominant.

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  • Secondary publication expected from 07.07.2022

Permalink: https://www.hzdr.de/publications/Publ-32907
Publ.-Id: 32907


Proton beam visualisation for in-beam MR imaging

Peter, J.; Schellhammer, S.; Gantz, S.; Uber, S.; van der Kraaij, E.; Smeets, J.; Karsch, L.; Pawelke, J.; Hoffmann, A. L.

Introduction
In-beam MRI is expected to improve the targeting accuracy of proton therapy for moving target volumes providing real-time anatomical images and allowing the simultaneous visualisation of the therapeutic proton beam in liquid-filled phantoms [1,2]. The aim of this contribution is to provide an overview of our previous work on MRI-based proton beam visualisation.

Materials & Methods
A 0.22 T open MR scanner was positioned at a fixed horizontal proton research beamline in a clinical proton therapy facility. Water, ethanol, petroleum and mayonnaise phantoms were irradiated with nominal proton beam energies between 190 - 225 MeV at beam currents of 1 - 64 nA. A range of pulse sequences was used for the acquisition of a horizontal slice within the beam volume. Material, sequence, beam current and energy dependence of the beam signal were evaluated.

Results
The proton beam induces a beam current and energy dependent MRI signal in liquids of low viscosity. For fixed beam current setting, the beam range in water extracted from the MR images matches the expected residual range within a few millimetres. Gradient echo-based pulse sequences appear more sensitive to the beam-induced effect than spin echo-based sequences.

Summary
The method holds potential for on-line quality assurance for MR-integrated proton therapy. The underlying image contrast mechanism requires elucidation to enable the development of specifically tailored sequences with increased sensitivity for the beam-induced effect.

Appendix 1

Figure 1: Beam current dependence of the 207 MeV beam signal in water acquired using a Time-of-Flight-Angiography sequence.


Figure 2: Inversion Recovery-Gradient Echo images of water under irradiation at a beam current of 9 nA. The dotted lines indicate the expected proton ranges.

References
[1] Schellhammer SM. Technical feasibility of MR-integrated proton therapy: Beam deflection
and image quality. Doctoral thesis, Technische Universität Dresden, 2019.
[2] Gantz S. Investigation of the physical and technical feasibility of MRI integrated proton
therapy using a horizontally scanning beam. Doctoral thesis, Technische Universität Dresden,
2021.

  • Open Access Logo Contribution to proceedings
    Joint Conference of the ÖGMP, DGMP & SGSMP, 21.09.2021, online, online, 978-3-948023-16-4, 212-213

Permalink: https://www.hzdr.de/publications/Publ-32906
Publ.-Id: 32906


Introduction to machine learning operations for HelmholtzAI

Sultova, N.

Introduction to machine learning operations for potential usage within HelmholtzAI

This presentation gives an overview of the machine learning operations landscape and our specific use case.

It further presents a detailed comparison between three potential candidates, Metaflow, MLflow and DVC and an outlook based on the gained information.

Keywords: machine learning; mlops; infrastructure; version control

  • Open Access Logo Lecture (others) (Online presentation)
    Voucher presentation at DESY, 13.07.2021, Dresden, Germany

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Permalink: https://www.hzdr.de/publications/Publ-32904
Publ.-Id: 32904


Sorption and reduction of uranium(VI) by a sulfate-reducing microorganism in synthetic Opalinus Clay pore water

Hilpmann, S.; Drobot, B.; Steudtner, R.; Bok, F.; Stumpf, T.; Cherkouk, A.

For a fully comprehensive safety concept of a nuclear repository, it is necessary to investigate not only the geological, geochemical and geophysical properties but also the influence of naturally occurring microorganisms in the deep geological layers. Clay rocks are a possible host rock formation for the long-term storage of the highly radioactive waste, with bentonite to be used as backfill material.
Various studies show that, among other sulfate-reducing microorganisms, Desulfosporosinus species are present in both clay rock and bentonite.[1,2] A phylogenetically close relative to the isolated species is Desulfosporosinus hippei DSM 8344, an anaerobic, spore-forming microorganism originally found in permafrost soils.[3] Therefore, this strain was selected to get a deeper insight into the uranium(VI) interactions with naturally occurring microorganisms from deep geological layers.
A time-dependent experiment in artificial Opalinus Clay pore water[4] (100 µM uranium(VI), pH 5.5) showed the removal of about 80 % of the uranium(VI) from the supernatants within 48 h. Corresponding live/dead images of the cells taken by fluorescence microscopy exhibit the formation of cell agglomerates and an increasing number of dead cells within the incubation time.
Further examination of the supernatants using time-resolved laser-induced fluorescence spectroscopic techniques revealed the presence of two uranium(VI) species, a lactate and a carbonate complex. The proportion of the carbonate species remained constant over the incubation period, whereas the lactate species decreased.
The comparison of UV/Vis band positions of the dissolved cell pellets with reference spectra provides clear proof of a partially reduction of uranium(VI) to uranium(IV), although bands of uranium(VI) were also still observable. Therefore, it could be that the ongoing interaction mechanism is a combined sorption-reduction process.
These findings are an important contribution to a safety concept for a nuclear repository in clay rock and provide new insights into the interactions of sulfate-reducing microorganisms with uranium(VI).

References
[1] Bagnoud et al. (2016) Nat. Commun 7, 1–10.
[2] Matschiavelli et al. (2019) Environ. Sci. Technol. 53, 10514–10524.
[3] Vatsurina et al. (2008) Int. J. Syst. Evol. Microbiol. 58, 1228–1232.
[4] Wersin et al. (2011) Appl. Geochemistry 26, 931–953.

Keywords: uranium(VI) reduction; sulfate-reducing microorganisms; clay rock

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

Permalink: https://www.hzdr.de/publications/Publ-32901
Publ.-Id: 32901


Superconductivity of highly spin-polarized electrons in FeSe probed by 77Se NMR

Molatta, S.; Opherden, D.; Wosnitza, J.; Opherden, L.; Zhang, Z. T.; Wolf, T.; von Löhneysen, H.; Sarkar, R.; Biswas, P. K.; Grafe, H.-J.; Kühne, H.

A number of recent experiments indicate that the iron-chalcogenide FeSe provides the long-sought possibility to study bulk superconductivity in the cross-over regime between the weakly coupled Bardeen-Cooper-Schrieffer (BCS) pairing and the strongly coupled Bose-Einstein condensation (BEC). We report on 77Se nuclear magnetic resonance experiments of FeSe, focused on the superconducting phase for strong magnetic fields applied along the c axis, where a distinct state with large spin polarization was reported. We determine this high-field state as bulk superconducting with high spatial homogeneity of the low-energy spin fluctuations. Further, we find that the static spin susceptibility becomes unusually small at temperatures approaching the superconducting state, despite the presence of pronounced spin fluctuations. Taken together, our results clearly indicate that FeSe indeed features an unusual field-induced superconducting state of a highly spin-polarized Fermi liquid in the BCS-BEC crossover regime.

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Permalink: https://www.hzdr.de/publications/Publ-32900
Publ.-Id: 32900


Simultaneous compression and opacity data from time-series radiography with a Lagrangian marker

Swift, D. C.; Kritcher, A. L.; Hawreliak, J. A.; Gaffney, J.; Lazicki, A.; Macphee, A.; Bachmann, B.; Döppner, T.; Nilsen, J.; Whitley, H. D.; Collins, G. W.; Glenzer, S.; Rothman, S. D.; Kraus, D.; Falcone, R. W.

Time-resolved radiography can be used to obtain absolute shock Hugoniot states by simultaneously measuring at least two mechanical parameters of the shock, and this technique is particularly suitable for one-dimensional converging shocks where a single experiment probes a range of pressures as the converging shock strengthens. However, at sufficiently high pressures, the shocked material becomes hot enough that the x-ray opacity falls significantly. If the system includes a Lagrangian marker such that the mass within the marker is known, this additional information can be used to constrain the opacity as well as the Hugoniot state. In the limit that the opacity changes only on shock heating, and not significantly on subsequent isentropic compression, the opacity of the shocked material can be determined uniquely. More generally, it is necessary to assume the form of the variation of opacity with isentropic compression or to introduce multiple marker layers. Alternatively, assuming either the equation of state or the opacity, the presence of a marker layer in such experiments enables the non-assumed property to be deduced more accurately than from the radiographic density reconstruction alone. An example analysis is shown for measurements of a converging shock wave in polystyrene at the National Ignition Facility.

Permalink: https://www.hzdr.de/publications/Publ-32899
Publ.-Id: 32899


Demonstration of an X-ray Raman Spectroscopy setup to study warm dense carbon at the High Energy Density Instrument of European XFEL

Voigt, K.; Zhang, M.; Ramakrishna, K.; Amouretti, A.; Appel, K.; Brambrink, E.; Cerantola, V.; Chekrygina, D.; Döppner, T.; Falcone, R. W.; Falk, K.; Fletcher, L. B.; Gericke, D. O.; Göde, S.; Harmand, M.; Hartley, N.; Hau-Riege, S. P.; Huang, L.; Humphries, O. S.; Lokamani, M.; Makita, M.; Pelka, A.; Prescher, C.; Schuster, A.; Smid, M.; Toncian, T.; Vorberger, J.; Zastrau, U.; Preston, T. R.; Kraus, D.

We present a proof-of-principle study demonstrating X-ray Raman Spectroscopy (XRS) from carbon samples at ambient conditions in conjunction with other common diagnostics to study warm dense matter, performed at the High Energy Density scientific instrument of the European X-ray Free Electron Laser (European XFEL). We obtain sufficient spectral resolution to identify the local structure and chemical bonding of diamond and graphite samples, using highly annealed pyrolytic graphite spectrometers. Due to the high crystal reflectivity and XFEL brightness, we obtain signal strengths that will enable accurate XRS measurements in upcoming pump-probe experiments with high repetition-rate, where the samples will be pumped with high-power lasers. Molecular dynamics simulations based on density functional theory together with XRS simulations demonstrate the potential of this technique and show predictions for high-energy-density conditions. Our setup allows simultaneous implementation of several di erent diagnostic methods to reduce ambiguities in the analysis of the experimental results, which, for warm dense matter, often relies on simplifying model assumptions. The promising capabilities demonstrated here provide unprecedented insights into chemical and structural dynamics in warm dense matter states of light elements, including conditions similar to the
interiors of planets, low-mass stars and other celestial bodies.

Permalink: https://www.hzdr.de/publications/Publ-32898
Publ.-Id: 32898


Enhanced Photoluminescence of Gold Nanoparticle-Quantum Dot Hybrids Confined in Hairy Polymer Nanofibers

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

In the present work, we have studied the influence of gold nanoparticles (AuNPs) on the photoluminescence (PL) behavior of cadmium selenide (CdSe) quantum dots (QDs) confined in spatially separated soft nanoscale cylindrical domains. These cylindrical domains, in the form of hairy core-shell nanofibers, were fabricated via cooperative self-assembly of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP) mixed with pre-synthesized CdSe QDs and AuNPs. The CdSe QDs and AuNPs were simultaneously incorporated in the P4VP cylindrical domains of the self-assembled BCP structure. It was found that the confinement imposed by the nanometer-sized cylindrical core resulted in the localization of the CdSe QDs and AuNPs in close proximity. Notably, it was observed that the PL intensity of the CdSe QDs could be manipulated by varying the amount of AuNPs present in the cylinder core. Interestingly, in the presence of a very low fraction of AuNPs, the PL intensity of the CdSe QDs increased compared to the AuNPs-free system. However, further increase in the fraction of AuNPs led to gradual quenching of the photoluminescence intensity. The PL enhancement and quenching plausibly was due to the interplay between the energy transfer due to surface plasmon coupling and FRET/electron transfer from QDs to the AuNPs. The resulting functional nanofibers could have potential applications in sensing, bioimaging, and optoelectronic devices.

Permalink: https://www.hzdr.de/publications/Publ-32897
Publ.-Id: 32897


Data publication: Optical Kerr nonlinearity and multi-photon absorption of DSTMS measured by Z-scan method

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

Z-scan data (polarization dependent)

Matlab scripts for the fitting and simulations

FTIR transmission data

------------------------------------------

Center wavelength of OPA: 1430 nm

FWHM duration of OPA pulses: 75 fs

Pulse energy: 20 nJ

thickness of DSTMS: 0.4 mm

'OA' means open aperture 'CA' meams close aperture

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-07-13
    DOI: 10.14278/rodare.1062
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-32894
Publ.-Id: 32894


Optical Kerr nonlinearity and multi-photon absorption of DSTMS measured by Z-scan method

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

We investigate the optical Kerr nonlinearity and multi-photon absorption (MPA) properties of 4-N, N-dimethylamino-4’-N’-methyl-stilbazolium 2, 4, 6- trimethylbenzene-sulfonate (DSTMS) excited by femtosecond pulses at a wavelength of 1.43 μm, which is optimal for terahertz generation via difference frequency mixing. The MPA and the optical Kerr coefficients of DSTMS at 1.43 μm are strongly anisotropic indicating a dominating contribution from cascaded 2nd-order nonlinearity.

Related publications

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  • Secondary publication expected from 09.08.2022

Permalink: https://www.hzdr.de/publications/Publ-32893
Publ.-Id: 32893


Investigations on axial gas dispersion coefficients in bubble columns using gas flow modulation

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

Gas-liquid contactors, such as bubble columns, are subject to dispersion phenomena in both gas and liquid phase. The Axial Dispersion Model (ADM) is the most widely used theoretical approach to account for the effects of dispersion [1].
A reliable quantification of the axial dispersion coefficients is crucial for process performance assessment as well as design and optimization of such contactors. Conventional approaches for determining axial dispersion coefficients rely on tracer substances. However, such methods are hardly universally applicable, may cause detrimental impurities or process downtimes and can even alter the physical properties of the system.
To overcome these issues, Döß et al. [2] introduced a novel non-invasive approach for determining the axial gas dispersion coefficient in bubble columns. Instead of a tracer substance, a marginal sinusoidal modulation is superimposed to the gas inlet flow rate and used as a virtual tracer. This modulation introduces a sinusoidal variation of the gas holdup in time, called gas density wave. Along the column, the gas density wave is damped in amplitude and is shifted in phase, due to gas dispersion. Amplitude damping and phase shift can be measured and related to the value of the axial dispersion coefficient via a dispersion model. A schematic sketch of the working principle is provided in Figure 1.
Döß et al. [2] successfully used sinusoidal-resolved gamma-ray densitometry to investigate the amplitude damping and phase shift. The deviation caused by the statistical behaviour of the gamma-ray photons was reduced by increasing the measurement time.As the operation of gamma-ray sources may be challenging for industrial applicability, this study assesses the possibility of using alternative non-radiative techniques to measure the gas density wave. Several measurement techniques and different gas modulation schemes in terms of initial modulation amplitude and frequency have been studied to ensure detectable amplitude and phase changes at chosen axial positions, while not altering the hydrodynamic behaviour. Uncertainties associated with the axial dispersion coefficient have been evaluated in comparison to gamma-ray densitometry.

  • Lecture (Conference) (Online presentation)
    European Chemical Engineering Conference, 20.-24.09.2021, Berlin, Germany

Permalink: https://www.hzdr.de/publications/Publ-32892
Publ.-Id: 32892


Convective, absolute and global azimuthal magnetorotational instabilities

Mishra, A.; Mamatsashvili, G.; Galindo, V.; Stefani, F.

We study the convective and absolute forms of azimuthal magnetorotational instability (AMRI) in a cylindrical Taylor–Couette (TC) flow with an imposed azimuthal magnetic field. We show that the domain of the convective AMRI is wider than that of the absolute AMRI. Actually, it is the absolute instability which is the most relevant and important for magnetic TC flow experiments. The absolute AMRI, unlike the convective one, stays in the device, displaying a sustained growth that can be experimentally detected. We also study the global AMRI in a TC flow of finite height using direct numerical simulation and find that its emerging butterfly-type structure – a spatio-temporal variation in the form of axially upward and downward travelling waves – is in a very good agreement with the linear analysis, which indicates the presence of two dominant absolute AMRI modes in the flow giving rise to this global butterfly pattern.

Keywords: absolute/convective instability; Taylor-Couette flow

Permalink: https://www.hzdr.de/publications/Publ-32890
Publ.-Id: 32890


Flow Reconstruction in a Rayleigh-Bénard Convection Cell with an Aspect Ratio 0.5 by Contactless Inductive Flow Tomography

Mitra, R.; Sieger, M.; Galindo, V.; Schindler, F.; Stefani, F.; Wondrak, T.

The time dependent behaviour of the large-scale circulation in a Rayleigh-Bénard convection cell exhibits a rich set of different three-dimensional flow features like rotations or torsional modes. In this paper, the applicability of the contactless inductive flow tomography (CIFT) to visualise these flow features in a cylindrical cell filled with GaInSn is investigated numerically. The simulated flow in the cylinder with a diameter of 320 mm and a height of 640 mm serves as a basis to investigate the quality of the reconstructed velocity field by CIFT.

Keywords: Rayleigh-Bénard convection; Large-scale circulation; Liquid metal flow; Contactless inductive flow tomography

Related publications

  • Open Access Logo Contribution to proceedings
    Electromagnetic Processing of Materials, 14.-16.06.2021, Riga, Latvia
    Proceedings of the 10th international conference in Electromagnetic Processing of Materials, Riga: The University of Latvia Press, 978-9934-18-686-8, 182-187
  • Lecture (Conference) (Online presentation)
    Electromagnetic Processing of Materials, 14.-16.06.2021, Riga, Latvia

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Permalink: https://www.hzdr.de/publications/Publ-32885
Publ.-Id: 32885


Radiative characterization of supersonic jets and shocks in a laser-plasma experiment

Bohlin, H.; Brack, F.-E.; Cervenak, M.; Chodukowski, T.; Cikhardt, J.; Dostál, J.; Dudžák, R.; Hubner, J.; Huo, W.; Jelinek, S.; Klír, D.; Kroll, F.; Krupka, M.; Krůs, M.; Pisarczyk, T.; Rusiniak, Z.; Schramm, U.; T.-H, N.-B.; Weber, S.; Zaraś-Szydłowska, A.; Zeil, K.; Kumar, D.; Schlegel, T.; Tikhonchuk, V.

The interaction of supersonic laser-generated plasma jets with a secondary gas target was studied experimentally. The plasma parameters of the jet, and the resulting shock, were characterized using a combination of multi-frame interferometry/shadowgraphy, and x-ray diagnostics, allowing for a detailed study of their structure and evolution. The velocity was obtained with an x-ray streak camera, and filtered x-ray pinhole imaging was used to infer the electron temperature of the jet and shock. The topology of the ambient plasma density was found to have a significant effect on the jet and shock formation, as well as on their radiation characteristics. The experimental results were compared with radiation hydrodynamic simulations, thereby providing further insights into the underlying physical processes of the jet and shock formation and evolution.

Keywords: Supersonic jets; Shocks; Laser Plasma; X-ray imaging; Hydrodynamic

Permalink: https://www.hzdr.de/publications/Publ-32883
Publ.-Id: 32883


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