Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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41396 Publications

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

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

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

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

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

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

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

Please find further information in the "supplementary information" file

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


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

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

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

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

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


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

Frenzel, M.

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

Keywords: mineral chemistry; sphalerite; pyrite

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

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


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

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

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

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

Related publications

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

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


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

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

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

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

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


Petawatt Femtosecond Laser Pulses from Titanium-Doped Sapphire Crystal

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

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

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


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

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

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

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


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

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

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

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


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

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

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

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


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

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

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

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

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

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

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


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

Cansever, H.; Lindner, J.

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

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

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


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

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

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

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


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

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

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

Permalink: https://www.hzdr.de/publications/Publ-32168
Publ.-Id: 32168


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

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

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

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

  • Open Access Logo Contribution to proceedings
    ISAV'20 In Situ Infrastructures for Enabling Extreme-Scale Analysis and Visualization at SC'20, 12.11.2020, New York, NY, USA
    ISAV'20: ISAV'20 In Situ Infrastructures for Enabling Extreme-Scale Analysis and Visualization
    DOI: 10.1145/3426462.3426472
    Cited 3 times in Scopus

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


SNT: A Unifying Toolbox for Quantification of Neuronal Anatomy

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

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

Keywords: Neuroanatomy; Morphology; Connectomics; Software; Neuroscience

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


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

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

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

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

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


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

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

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

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


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

Füssel, T.

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

Keywords: Technetium; Alumina; Heteroreduction; Immobilization

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

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


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

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

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

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

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


Magnetic field-induced phase transitions in antiferromagnetic rings

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

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

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

Keywords: antiferromagnetism; curvilinear magnetism

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

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


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

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

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

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


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

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

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

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

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

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


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

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

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

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


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

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

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

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


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

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

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

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


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

Thomas, E.; Krause, M.

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

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


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

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

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

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

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


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

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

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

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

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


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

Nestle, U.; Krause, M.

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

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


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

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

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

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

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


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

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

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

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


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

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

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

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

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


Men who stare at bone: multimodal monitoring of bone healing

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

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

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

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


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

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

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

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

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

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Permalink: https://www.hzdr.de/publications/Publ-32146
Publ.-Id: 32146


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

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

calorimetry data in excel format

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


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

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

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

DOI: 10.1038/s41467-020-16133-8

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

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


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

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

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

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Permalink: https://www.hzdr.de/publications/Publ-32143
Publ.-Id: 32143


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

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

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

Keywords: ZnO; doping; photoluminescence

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


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

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

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

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

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


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

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

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

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

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


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

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

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

Keywords: Solar cells; Si; doping; defects

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Permalink: https://www.hzdr.de/publications/Publ-32139
Publ.-Id: 32139


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

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

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

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

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


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

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

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

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

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Permalink: https://www.hzdr.de/publications/Publ-32137
Publ.-Id: 32137


Pushing the doping limit for future FETs

Zhou, S.

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

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

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


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

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

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

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

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Permalink: https://www.hzdr.de/publications/Publ-32135
Publ.-Id: 32135


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

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

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

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

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


Ansible GitLab Base Role

Hüser, C.; Ziegner, N.; Huste, T.

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

Keywords: gitlab; ansible

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

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


Ansible Role Redis

Hüser, C.; Ziegner, N.; Huste, T.

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

Keywords: redis; ansible; cache; high availability

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

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


Ansible Role HAProxy

Hüser, C.; Ziegner, N.; Huste, T.

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

Keywords: haproxy; loadbalancer; networking; web; ansible

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

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


Ansible Role GitLab

Hüser, C.; Huste, T.; Ziegner, N.

Ansible role to configure GitLab Omnibus installation.

Keywords: gitlab; ansible

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

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


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

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

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

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

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


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

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

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

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

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


Proposal for the delineation of neoadjuvant target volumes in oesophageal cancer

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

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

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

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Publ.-Id: 32127


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

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

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

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

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


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

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

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

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

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


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

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

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

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

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

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Permalink: https://www.hzdr.de/publications/Publ-32124
Publ.-Id: 32124


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

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

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

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

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


Teaching ML in Compact Courses

Fouilloux, A.; Steinbach, P.

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

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

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

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Permalink: https://www.hzdr.de/publications/Publ-32121
Publ.-Id: 32121


Teaching ML in Compact Courses

Fouilloux, A.; Steinbach, P.

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

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

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

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


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

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

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

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

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


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

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

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

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

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


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

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

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

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

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


Towards a first Joule-level activation of PEnELOPE

Löser, M.; Siebold, M.; Schramm, U.

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

Keywords: laser; diode pumped; ytterbium; CPA

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

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


Non-reciprocal spin wave propagation in magnetic bilayer structures

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

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

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

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

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


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

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

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

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


Impact of Surface Reactivity on the Simulation of Mineral Dissolution Rates

Schabernack, J.; Fischer, C.

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

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

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

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

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


Development of Machine Learning Framework for Interfacial Force Closures Based on Bubble Tracking Data

Tai, C.-K.; Lucas, D.; Bolotnov, I.

This work aims to develop data-driven modeling framework with the aid of machine learning methods and high-fidelity dataset. To gain confidence on the methodology, a bubble drag regression task using artificial dataset is conducted. Result shows FNN’s capability performing non-linear fitting. On the other hand, the sample size test would give sense on model underfitting with same amount of knowledge. Inspired by the previous task, the focus then moved on to utilize DNS bubble tracking dataset for modeling interfacial momentum exchange terms. A novel way to approach interfacial momentum exchange is proposed. Preliminary result reveals the concern of model accuracy on unseen data points. Improvement on model generalization is suggested. Also, further refinement on label formation and data processing should be taken care of. Nonetheless, the potential using high fidelity data and NN to directly model interaction between phases in bubbly flow has been shown.

Keywords: DNS; bubbly flow; drag; machine learning

  • Contribution to proceedings
    2020 ANS Virtual Winter Meeting, 16.-19.11.2020, Online, USA
  • Lecture (Conference) (Online presentation)
    2020 ANS Virtual Winter Meeting, 16.-19.11.2020, Online, USA

Permalink: https://www.hzdr.de/publications/Publ-32111
Publ.-Id: 32111


Stress-Induced Modification of Gyration Eigen-Frequencies in Stacked Double-Vortex Structures

Iurchuk, V.; Kakay, A.; Deac, A. M.

The ground state of nanoscale circular magnetic disks of certain geometric aspect ratios is a spontaneously forming stable vortex configuration with circulating in-plane magnetization and a vortex core pointing out-of-plane. Resonantly exciting the VC via either an rf magnetic field or an rf spin-polarized current yields a gyrotropic motion around its equilibrium position, characterised by a specific eigen-frequency, which depends on the material parameters and the disk geometry [1]. Such oscillations, which can be read out via periodic magnetoresistance changes, generate rf signals with high quality factors (>10000) in the sub-GHz bandwidth [2,3]. While all these features make vortex-based nano-oscillators interesting as nanoscale rf sources, the major drawback remains their low frequency tunability associated with the linear characteristics of the gyrotropic mode.
Here, we investigate the role of magnetostriction in improving the tunability of vortex nano-oscillators. Specifically, we consider a double-disk structure comprising magnetostrictive (CoFe) and non-magnetostrictive (Py) layers separated vertically by a non-magnetic spacer. We show that, when the two vortices have different eigen-frequencies and the magnetostatic coupling between them is sufficiently strong, the stress-induced magnetoelastic anisotropy can lead to the synchronized gyration of the two vortex cores (Fig. 1). The stress-induced transition from double-frequency to single-frequency dynamics is mostly controlled by the polarization of the vortices and the magnetostatic coupling strength (i.e. spacer thickness). These findings offer a frequency tunability of vortex-based oscillators via mechanical stress, which can be generated and controlled electrically, for example, using piezoelectric substrates [4].

Funding from the EU Horizon 2020 project No. 737038 (TRANSPIRE) is acknowledged.

[1] K. Yu. Guslienko, et al, J. Appl. Phys. 91, 8037 (2002).
[2] A. Dussaux, et al, Nat. Commun. 1, 1 (2010).
[3] N. Locatelli, et al, Appl. Phys. Lett. 98, 062501 (2011).
[4] M. Filianina, et al, Appl. Phys. Lett. 115, 062404 (2019).

Keywords: Magnetic vortex; Micromagnetic modelling; Magnetoelastic effect

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

Permalink: https://www.hzdr.de/publications/Publ-32110
Publ.-Id: 32110


Synthesis, structure and magnetic properties of Sm1.2Ho0.8Fe17Нx (x = 0; 4.4)

Veselova, S. V.; Paukov, M. A.; Tereshina, I. S.; Verbetsky, V. N.; Zakharov, K. V.; Gorbunov, D.; Vasil`Ev, A. N.

Intermetallic compounds based on rare-earth metals and iron are by far the most promising materials for permanent magnets. In this work, the multicomponent compound Sm1.2Ho0.8Fe17 was prepared by induction melting. The hydride Sm1.2Ho0.8Fe17H4.4 with a high hydrogen content was obtained by direct hydrogenation of the intermetallic compound. The rhombohedral Th2Zn17-type of structure (space group R3m) is inherent to parent compound and hydride as well. The effect of hydrogenation on the magnetic properties of Sm1.2Ho0.8Fe17 was investigated. Curie temperature of the hydride Sm1.2Ho0.8Fe17H4.4 is higher than that of parent compound by ΔTC = 138 K. The hydrogen embedded in Sm1.2Но0.8Fe17 crystal lattice increases the saturation magnetization (σS) at T = 300 K, but does not significantly affect σS at Т = 4.2 K. The ferrimagnetic structure is retained in magnetic fields up to 58 T in the parent compound, while, in the hydride, there is a spin-reorientation phase transition observed at 55 T. It is found that the parameter of the intersublattice exchange interaction decreases significantly in the hydride Sm1.2Ho0.8-Fe17H4.4 (and in the nitride Sm1.2Ho0.8Fe17N2.4) which is associated with boosting of the unit-cell volume and distances between magnetic ions.

Permalink: https://www.hzdr.de/publications/Publ-32109
Publ.-Id: 32109


He⁺ Ion Irradiation Induced Sn Extrusion out of SnO Covered Tin Spheres – a Combined Computer Simulation of Defect Generation and Defect Kinetics

Tucholski, D.; Heinig, K.-H.; Möller, W.; Klingner, N.; Hlawacek, G.; Facsko, S.; Hübner, R.

Here we report on a combined computer simulation of defect generation and defect kinetics for 30 keV He⁺ ion irradiation of sub-μm-scale tin spheres. In the process to be simulated, the irradiation was performed in a Helium Ion Microscope which allows the in-situ monitoring of morphological changes of the nanospheres during He⁺ ion irradiation. Above a He⁺ fluence of ∼10¹⁷ /cm², Sn extrusions appear on the surface of the spheres. Initially, small, pyramidally facetted extrusions evolve at the equator of the tin spheres (north pole pointing to the ion source), later on each sphere becomes completely covered with tin, then turning into facetted single crystals. No Sn extrusions were observed for tin spheres with diameters smaller than ∼100nm. Transmission electron microscopy and Auger electron spectroscopy investigations show that the tin spheres are covered with a few-nm-thick SnO skin and that the extrusions are single crystals.
For the computer simulations a model was developed which assumes that He⁺ ions generate interstitials ISn and vacancies VSn in the body-centered tetragonal lattice of tin. Due to the SnO skin, the ISn and VSn are confined to the tin sphere. A coherent Sn-SnO interface with a strong Sn-SnO interaction prevents ISn and VSn annihilation and void formation here. The projected range of 30 keV He⁺ ions is smaller than the diameter of the sub-μm spheres, the He accumulates and partly fills the VSn. Thus, the “pressure” of ISn increases steadily. Simultaneously, He⁺ ion erosion creates openings in the SnO skin. The sputter coefficient increases with the angle of incidence, thus openings in the SnO skin form at the equator regions first. Once the tin interstitials find such an opening in the SnO skin, they can escape from the interior of the Sn sphere and form an epitaxial, regular Sn lattice outside. Due to the high Sn-SnO bond strength the extruded tin wets the outer SnO surface.
The defect generation at He⁺ ion irradiation was simulated with TRI3DYN [1], a 3D program calculating atomic displacements in the binary collision approximation. The reaction-diffusion behavior of the ISn and VSn as well as their clustering into voids and growth to extrusions were simulated with a 3D kinetic lattice Monte Carlo program [2] using an RGL potential for tin. The simulated reaction pathway of the morphology agrees very well with the sequence of HIM images taken during He⁺ ion irradiation. A quantitative comparison of the extruded material with simulations provides conclusions on the defect kinetics under ion irradiation.

[1] Möller, Nucl. Instr. Meth. B 322 (2014) 23
[2] Strobel et al., Phys. Rev. B 64 (2001) 245422

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  • Lecture (Conference) (Online presentation)
    2021 Spring Meeting of the European Materials Research Society (E-MRS) / Symposium L - New developments in the modeling and analysis of radiation damage in materials II, 31.05.-04.06.2021, ONLINE, ONLINE

Permalink: https://www.hzdr.de/publications/Publ-32108
Publ.-Id: 32108


Effect of power ultrasound on wettability and collector-less floatability of chalcopyrite, pyrite and quartz

Ahmad, H.; Hamed, G.; Safak, G. Ö.; Tomasz, N.; Agnieszka, S.

Numerous studies have addressed the role of ultrasonication on floatability of minerals macroscopically. However, the impact of acoustic waves on the mineral hydrophobicity and its physicochemical aspects were entirely overlooked in the literature. This paper mainly investigates the impact of ultrasonic power and its time on the wettability and floatability of chalcopyrite, pyrite and quartz. For this purpose, contact angle and collectorless microflotation tests were implemented on the ultrasonic-pretreated and non-treated chalcopyrite, pyrite and quartz minerals. The ultrasonic process was carried out by a probe-type ultrasound (Sonopuls, 20 kHz and 60 W) at various ultrasonication time (0.5–30 min) and power (0–180 W) while the dissolved oxygen (DO), liquid temperature, conductivity (CD) and pH were continuously monitored. Comparative assessment of wettabilities in the presence of a constant low-powered (60 W) acoustic pre-treatment uncovered that surface of all three minerals became relatively hydrophilic. Meanwhile, increasing sonication intensity enhanced their hydrophilicities to some extent except for quartz at the highest power-level. This was mainly related to generation of hydroxyl radicals, iron-deficient chalcopyrite and elemental sulfur (for chalcopyrite), formation of OH and H radicals together with H2O2 (for pyrite) and creation of SiOH (silanol) groups and hydrogen bond with water dipoles (for quartz). Finally, it was also found that increasing sonication time led to enhancement of liquid temperature and conductivity but diminished pH and degree of dissolved oxygen, which indirectly influenced the mineral wettabilities and floatabilities. Although quartz and pyrite ultrasound-treated micro-flotation recoveries were lower than that of conventional ones, an optimum power-level of 60–90 W was identified for maximizing chalcopyrite recovery.

Keywords: froth flotation; power ultrasound; ultrasonic treatment; chalcopyrite-pyrite-quartz flotation system; hydrophobicity

Permalink: https://www.hzdr.de/publications/Publ-32107
Publ.-Id: 32107


Transformation of tin spheres into hollow cubes by He+ irradiation

Klingner, N.; Heinig, K.-H.; Tucholski, D.; Möller, W.; Hübner, R.; Hlawacek, G.; Facsko, S.

Broad ion irradiation of nanoobjects can considerably change their shape. Examples are ion-beam hammering [1], ion-induced shaping of buried particles [2], and ion-induced viscous flow of nanopillars [3]. Such shape changes are mainly driven by the kinetics of defects generated by binary collisions of ions and recoils. Here we report a new kind of ion-induced structure evolution.
Sub-micrometer Sn spheres were irradiated with 30 keV He+ ions in a Helium Ion Microscope (HIM). Above a He+ fluence of ~ 10E17 /cm², Sn extrusions appear on the surface of the spheres and were imaged with the HIM. Initially, small, pyramid-like facetted extrusions form at the equator of the tin spheres (north pole pointing to the ion source). Later, each sphere becomes completely covered with tin and appears like a facetted single crystal cube. No Sn extrusions were observed for tin spheres with diameters smaller than ~100 nm. Transmission Electron Microscopy and Auger electron spectroscopy studies show that the tin spheres are covered with a few nm thick SnOx skin and that the extrusions are single crystals.

A model was developed which assumes that the He+ ions generate Frenkel pairs in the body-centered tetragonal lattice of tin. The point defects are confined to the tin sphere by the SnO skin, and there is no preferred nucleation or annihilation of the point defects at the Sn-SnO interface. The recombination of interstitials with vacancies is partly inhibited by occupation with He atoms. This results in an increasing pressure of the “interstitial gas”. Simultaneously, He+ ion erosion creates openings in the SnO skin. The sputter coefficient increases with the angle of incidence, so that openings in the SnO skin form in the equator regions first. Once the tin interstitials find an opening in the SnO skin, they can escape from the interior of the Sn sphere and form an epitaxial regular Sn lattice on the outside. Due to the high Sn-SnO bond strength, the extruded tin wets the outer SnO surface.

Computer simulations were performed based on this model. The Frenkel pair generation and the SnO skin sputtering are simulated with dynamical programs based on the Binary Collision Approximation TRI3DYN [4]. Reaction-diffusion dynamics as well as nucleation and extended defect growth were simulated with a 3D kinetic lattice Monte Carlo program [5] using an RGL-potential for tin. The formation of cavities and their filling with He reproduces the experimentally observed tendency for hollow cube formation.

[1] Snoeks et al., Nucl. Instr. Meth B 178 (2001) 62
[2] Schmidt et al., Nucl. Instr. Meth. B 267 (2009) 1345
[3] Xu et al., Semicond. Sci. Technol. 35 (2020) 15021
[4] Möller, Nucl. Instr. Meth. B 322 (2014) 23
[5] Strobel et al., Phys. Rev. B 64 (2001) 245422

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  • Lecture (Conference) (Online presentation)
    European Materials Research Society 2021 Spring Meeting, 31.05.-04.06.2021, ONLINE, ONLINE
  • Invited lecture (Conferences) (Online presentation)
    FIB SIG User Group Meeting, 24.-25.09.2021, St Lucia Qld, Australia

Permalink: https://www.hzdr.de/publications/Publ-32106
Publ.-Id: 32106


Magnetic structure of the quantum magnet SrCuTe2O6

Chillal, S.; Isman, A. T. M. N.; Luetkens, H.; Canévet, E.; Scurschii, I.; Khalyavin, D.; Lake, B.

SrCuTe2O6 consists of a three-dimensional arrangement of spin-1/2 Cu2+ ions. The first-, second-, and third-neighbor interactions, respectively, couple Cu2+ moments into a network of isolated triangles, a highly frustrated hyperkagome lattice consisting of corner-sharing triangles and antiferromagnetic chains. Of these, the chain interaction dominates in SrCuTe2O62O6 using muon relaxation spectroscopy and neutron diffraction and present the low-temperature magnetic structure as well as the directional-dependent magnetic phase diagram as a function of field.

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Permalink: https://www.hzdr.de/publications/Publ-32105
Publ.-Id: 32105


Momentum distribution function and short-range correlations of the warm dense electron gas -- ab initio quantum Monte Carlo results

Hunger, K.; Schoof, T.; Dornheim, T.; Bonitz, M.; Filinov, A.

In a classical plasma the momentum distribution, n(k), decays exponentially, for large k, and the same is observed for an ideal Fermi gas. However, when quantum and correlation effects are relevant simultaneously, an algebraic decay, n∞(k)∼k−8 has been predicted. This is of relevance for cross sections and threshold processes in dense plasmas that depend on the number of energetic particles. Here we present the first \textit{ab initio} results for the momentum distribution of the nonideal uniform electron gas at warm dense matter conditions. Our results are based on first principle fermionic path integral Monte Carlo (CPIMC) simulations and clearly confirm the k−8 asymptotic. This asymptotic behavior is directly linked to short-range correlations which are analyzed via the on-top pair distribution function (on-top PDF), i.e. the PDF of electrons with opposite spin. We present extensive results for the density and temperature dependence of the on-top PDF and for the momentum distribution in the entire momentum range.

Permalink: https://www.hzdr.de/publications/Publ-32103
Publ.-Id: 32103


Preclinical evaluation of [18F]FACH in healthy mice and piglets: An 18F-labeled ligand for imaging of monocarboxylate transporters with PET

Gündel, D.; Sadeghzadeh, M.; Deuther-Conrad, W.; Wenzel, B.; Cumming, P.; Toussaint, M.; Ludwig, F.-A.; Moldovan, R.-P.; Kranz, M.; Teodoro, R.; Sattler, B.; Sabri, O.; Brust, P.

: The expression of monocarboxylate transporters (MCTs) is linked to pathophysiological changes in diseases including cancer, such that MCTs could potentially serve as diagnostic markers or therapeutic targets. We recently developed [18F]FACH as a radiotracer for non-invasive molecular imaging of MCTs by positron emission tomography (PET). The aim of this study was to evaluate further the specificity, metabolic stability, and pharmacokinetics of [18F]FACH in healthy mice and piglets. We measured the [18F]FACH plasma protein binding fractions in mice and piglets and the specific binding in cryosections of murine kidney and lung. The biodistribution of [18F]FACH was evaluated by tissue sampling ex vivo and by dynamic PET/MRI in vivo, with and without pre-treatment by the MCT inhibitor α-CCA-Na or the reference compound, FACH-Na. Addition-ally, we performed compartmental modelling of the PET signal in kidney cortex and liver. Satu-ration binding studies in kidney cortex cryosections indicated a KD of 118±12 nM and Bmax of 6.0 pmol/mg wet weight. The specificity of [18F]FACH uptake in the kidney cortex was confirmed in vivo by reductions in AUC0-60min after pre-treatment with α-CCA-Na in mice (-47%) and in piglets (-66%). [18F]FACH was metabolically stable in mouse, but polar radio-metabolites were present in plasma and tissues of piglets. The [18F]FACH binding potential (BPND) in the kidney cortex was approximately 1.3 in mice. [18F]FACH has suitable properties for the detection of the MCTs in kidney, and thus has potential as a molecular imaging tool for MCT-related pathologies, which should next be assessed in relevant disease models.

Keywords: monocarboxylate transporters (MCTs); [18F]FACH; PET imaging; metabolism; kidney; cancer

Permalink: https://www.hzdr.de/publications/Publ-32102
Publ.-Id: 32102


Small scale short circuits due to metal-droplet transfer in liquid metal batteries

Benard, S.; Landgraf, S.; Weber, N.; Weier, T.

Liquid metal batteries (LMBs) have been discussed as stationary energy storage for integrating highly volatile renewable energy sources into the electric grid. The cheap and abundant electrode materials, extreme current densities and potentially very long life time make LMBs excellent candidates for storage applications. As a typical cell, Li-Bi LMBs consist of a molten Bi-electrode on the bottom, an ion-conducting liquid electrolyte in the middle and a molten Li-electrode on the top – as illustrated schematically in Fig. 1. In order to avoid contact of the anode with the cell housing, the molten Li is typically contained in a solid Ni-Fe foam. During discharge, the anode metal Li is oxidized, and the ion crosses the electrolyte layer before alloying with the molten Bi. At charge, this process is reversed and Li de-alloyed and transferred back into the metal-foam anode.
When cycling such batteries for several days, sometimes short voltage drop-offs can be observed. As illustrated in Fig. 1, such quick changes of the cell potential can most probably be explained by a sudden non-faradaic Li-transfer from the anode to the cathode. After operating Li-Bi cells and removing the current collector with the Ni-Fe-foam, sometimes solid spots, formed of an intermetallic phase, can be observed below of the foam – as shown in the inset in Fig. 1. These intermetallic phases can appear only if Bi from the cathode touches the anode, e.g. during a localized short circuit. Considering that the metal foam reacts slightly with the molten salt, it might happen that the wetting behavior between molten Li and foam changes with time. A missing wetting could – finally – lead to the formation of small Li-droplets below of the foam when charging the cell. If such droplets grow too much, they might lead to a local short circuit and may thus explain the phenomena illustrated in Fig. 1. Bases on this motivation, the formation, detachment and transport of such droplets as well as a possible short circuit is studied.

  • Lecture (Conference)
    Electromagnetic processing of materials, 13.-17.06.2021, Riga, Lettland

Permalink: https://www.hzdr.de/publications/Publ-32100
Publ.-Id: 32100


Suppression of Metastatic Melanoma Growth in Lung by Modulated Electro-Hyperthermia Monitored by a Minimally Invasive Heat Stress Testing Approach in Mice

Thomas, M. J.; Major, E.; Benedek, A.; Horvath, I.; Mathe, D.; Bergmann, R.; Szasz, A. M.; Krenacs, T.; Benyo, Z.

Modulated electro-hyperthermia (mEHT) is a novel complementary therapy in oncology which is based on the higher conductivity and permittivity of cancerous tissues due to their enhanced glycolytic activity and ionic content compared to healthy normal tissues. We aimed to evaluate the potential of mEHT, inducing local hyperthermia, in the treatment of pulmonary metastatic melanoma. Our primary objective was the optimization of mEHT for targeted lung treatment as well as to identify the mechanism of its potential anti-tumor effect in the B16F10 mouse melanoma pulmonary metastases model while investigating the potential treatment-related side effects of mEHT on normal lung tissue. Repeated treatment of tumor-bearing lungs with mEHT induced significant anti-tumor effects as demonstrated by the lower number of tumor nodules and the downregulation of Ki67 expression in treated tumor cells. mEHT treatment provoked significant DNA double-strand breaks indicated by the increased expression of phosphorylated H2AX protein in treated tumors, although treatment-induced elevation of cleaved/activated caspase-3 expression was insignificant, suggesting the minimal role of apoptosis in this process. The mEHT-related significant increase in p21waf1 positive tumor cells suggested that p21waf1-mediated cell cycle arrest plays an important role in the anti-tumor effect of mEHT on melanoma metastases. Significantly increased CD3+, CD8+ T-lymphocytes, and F4/80+CD11b+ macrophage density in the whole lung and tumor of treated animals emphasizes the mobilizing capability of mEHT on immune cells. In conclusion, mEHT can reduce the growth potential of melanoma, thus offering itself as a complementary therapeutic option to chemo- and/or radiotherapy.

Keywords: B16F10 melanoma; DNA double-strand breaks; cell cycle arrest; immune cell mobilization; modulated electro-hyperthermia; pulmonary metastases

Permalink: https://www.hzdr.de/publications/Publ-32099
Publ.-Id: 32099


Solar and anthropogenic influences on climate: Regression analysis and tentative predictions

Stefani, F.

The two main drivers of climate change on sub-Milankovitch time scales are re-assessed by means of a double regression analysis. Evaluating linear combinations of the logarithm of carbon dioxide concentration and the geomagnetic aa-index as a proxy for solar activity, we reproduce the sea surface temperature (HadSST) since the middle of the 19th century with an adjusted R² value of around 87 per cent for a climate sensitivity (of TCR type) in the range of 0.6 K until 1.6 K per doubling of CO₂ . The solution of the regression is quite sensitive: when including data from the last decade, the simultaneous occurrence of a strong El Niño and low aa-values lead to a preponderance of solutions with relatively high climate sensitivities around 1.6 K. If those later data are excluded, the regression delivers a significantly higher weight of the aa-index and correspondingly a lower climate sensitivity going down to 0.6 K. The plausibility of such low values is discussed in view of recent experimental and satellite-borne measurements. We argue that a further decade of data collection will be needed to allow for a reliable distinction between low and high sensitivity values. Based on recent ideas about a quasi-deterministic planetary synchronization of the solar dynamo, we make a first attempt to predict the aa-index and the resulting temperature anomaly for various typical CO₂ scenarios. Even for the highest climate sensitivities, and an unabated linear CO₂ increase, we predict only a mild additional temperature rise of around 1 K until the end of the century, while for the lower values an imminent temperature drop in the near future, followed by a rather flat temperature curve, is prognosticated.

Keywords: Climate change; Solar cycle; Forecast

Permalink: https://www.hzdr.de/publications/Publ-32098
Publ.-Id: 32098


Metal ion size profoundly affects H3glyox chelate chemistry

Choudhary, N.; Barett, K.; Kubeil, M.; Radchenko, V.; Engle, J.; Stephan, H.; de Guadalupe Jaraquemada-Pelaez, M.; Orvig, C.

The bisoxine hexadentate chelating ligand H3glyox was investigated for its affinity for Mn2+, Cu2+ and Lu3+ ions; all three metal ions are medicinally relevant with applications in nuclear medicine and medicinal inorganic chemistry. The aqueous coordination chemistry and thermodynamic stability of all three metal complexes was thoroughly investigated by detailed DFT structure calculations and stability constant determination, by employing UV in-batch spectrophotometric titrations, giving pM values – pCu (25.2) > pLu (18.1) > pMn (12.0). DFT calculated structures revealed different geometries and coordination preferences of the three metal ions; notable was an inner sphere water molecule in the Mn2+ complex. H3glyox labels [52Mn]Mn2+, [64Cu]Cu2+ and [177Lu]Lu3+ at ambient conditions with apparent molar activities of 40 MBq/mol, 500 MBq/mol and 25 GBq/mol, respectively. Collectively, these initial investigations provide significant insight into the effects of metal ion size and charge on the chelation with the hexadentate H3glyox and the potential use of the Mn2+-H3glyox complex in 52/55Mn-based bimodal imaging.

Permalink: https://www.hzdr.de/publications/Publ-32097
Publ.-Id: 32097


Radial pressure forces in Euler-Euler simulations of turbulent bubbly pipe flows

Rzehak, R.; Liao, Y.; Meller, R.; Schlegel, F.; Lehnigk, R.; Lucas, D.

Two-equation turbulence models based on the Boussinesq eddy viscosity hypothesis that have been used in the vast majority of previous simulation studies on bubbly pipe flows contain a term which renders the radial pressure distribution non-constant. In single phase simulations this effect is invariably absorbed in the definition of a modified pressure, from which the real pressure may be recovered if necessary. For bubbly multiphase flows however, this is not possible since the bubbles experience a force which depends, of course, on the real pressure rather than the modified one. As it turns out, most software codes by default rely on the approximation of neglecting the difference between modified and real pressure for bubbly flows. The purpose of the present study is to assess the influence of this approximation on the final simulations results. Fortunately it turns out that at least for the conditions considered in this study, the error is small.

Keywords: turbulent dispersed gas liquid multiphase flow; Euler-Euler two fluid model; closure relations; CFD

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Permalink: https://www.hzdr.de/publications/Publ-32095
Publ.-Id: 32095


Synthesis and radiofluorination of [18F]F-BAY-8002: A novel potential radiotracer for PET imaging of monocarboxylate transporter 1

Sadeghzadeh, M.; Wenzel, B.; Ludwig, F.-A.; Kopka, K.; Moldovan, R.-P.; Brust, P.

Objectives: The monocarboxylate transporters 1 and 4 (MCT1/4) are integral plasma membrane proteins that bi-directionally transport lactate as well as small monocarboxylated molecules. They are highly expressed in several tumors. BAY-8002 belongs to a class of compounds that have been identified as novel and specific MCT1 inhibitors based on functional high-throughput screening assays using a panel of cell lines highly sensitive towards MCT1 inhibition [1]. IC50 values of 1 to 12 nM and ca. 500–fold selectivity towards MCT4 have already been reported for BAY-8002 [1]. Here we designed an 18F-labeled analog of BAY-8002 ([18F]F-BAY-8002) aiming to image mainly MCT1 upregulation considering the fact that the absence of MCT4 expression in many types of cancer may not be necessarily sufficient as a single marker to predict treatment response [2].
Methods: BAY-8002 and its novel fluorinated analog (F-BAY-8002) were synthesized based on reported procedures [1]. As BAY-8002 already contains a chloro substituent which could serve as leaving group, the compound was considered as precursor for radiofluorination via a halogen-fluorine exchange approach (Figure 1A). [18F]F-BAY-8002 was radiolabeled via a one-step aromatic nucleophilic substitution reaction (SNAr) using 2-5 mg of precursor in the presence of the [18F]KF/K222/K2CO3 complex in dimethyl sulfoxide (DMSO) at 150 °C within 5 min (Figure 1B).

Figure 1. (A) Synthesis of BAY-8002 and its novel fluorinated analog; (B) Radiosynthesis of [18F]F-BAY-8002.
Separation of [18F]F-BAY-8002 from the chlorinated precursor was performed by semi-preparative HPLC. The tracer was finally purified via solid-phase extraction (Sep-Pak® C18 light cartridge) and formulated in 10% EtOH/saline solution to be ready for biological evaluations.
Results: Despite using identical conditions [1], the novel fluorinated analog F-BAY-8002 was obtained in only 4% overall yield due to formation of by-products which have not been observed during the synthesis of BAY-8002 (35% overall yield). Due to the lack of commercially available radioligands, the MCT1 affinity (Ki) of F-BAY-8002 could not yet be determined and we therefore intend to measure the KD value of our new radiotracer by in-house established methods in near future. The novel radiotracer [18F]F-BAY-8002 was synthesized in 30 ± 9% radiochemical yields (n = 4, non-isolated, estimated by radio-HPLC) within 5 min reaction time. After purification and formulation, the final product was obtained with a radiochemical purity of > 99% (n = 1). Further radiochemical characterization of the radiotracer and the transfer of the radiosynthesis to an automated module are in progress.
Conclusions: A novel 18F-labeled radioligand for potential specific MCT1-targeted imaging was developed via a straightforward fast approach in good radiochemical yields and high radiochemical purity. Notably, the labeling was successful even without protection of the carboxylic acid group resulting in a beneficial one-step instead of a two-step radiosynthesis procedure. In vitro and in vivo biological evaluation of the newly synthesized MCT1 radioligand are currently ongoing.
References: [1] Quanz, M. et al. Mol Cancer Ther. 2018 17:2285-2296; [2] Le Floch, R. et al. Proc Natl Acad Sci USA. 2011 108:16663-8.

Keywords: Radiofluorination; Monocarboxylate transporter 1; BAY-8002; PET imaging; Cancer

  • Contribution to proceedings
    virtual SRS meeting, 17.-19.05.2021, online, online
    Nuclear Medicine and Biology 96-97, Suppl., Nuclear Medicine and Biology, S74-S75
    DOI: 10.1016/S0969-8051(21)00386-3

Permalink: https://www.hzdr.de/publications/Publ-32094
Publ.-Id: 32094


Magnetische Kühlung

Gottschall, T.

  • Lecture (others)
    Seniorenakademie der TU Dresden, 15.09.2020, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-32093
Publ.-Id: 32093


Advanced characterization of multicaloric materials in pulsed magnetic fields

Gottschall, T.

es hat kein aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences) (Online presentation)
    JEMS 2020, 07.12.2020, Lissabon, Portugal

Permalink: https://www.hzdr.de/publications/Publ-32092
Publ.-Id: 32092


Dynamics of Rising Bubbles in a Quiescent Slag Bath with Varying Thermo-Physical Properties

Reuter, M. A.; Obiso, D.; Schwittala, D. H.; Korobeinikov, I.; Meyer, B.; Richter, A.

The motion of bubbles in a liquid slag bath with temperature gradients is investigated by means of 3D fluid dynamic computations. The goal of the work is to describe the dynamics of the rising bubbles, taking into account the temperature dependency of the thermo-physical properties of the slag. Attention is paid to the modeling approach used for the slag properties and how this affects the simulation of the bubble motion. In particular, the usage of constant values is compared to the usage of temperature-dependent data, taken from models available in the literature and from in-house experimental measurements. Although the present study focuses on temperature gradients, the consideration of varying thermo-physical properties is greatly relevant for the fluid dynamic modeling of reactive slag baths, since the same effect is given by heterogeneous species and solid fraction distributions. CFD is applied to evaluate the bubble dynamics in terms of the rising path, terminal bubble shape, and velocity, the gas–liquid interface area, and the appearance of break-up phenomena. It is shown that the presence of a thermal gradient strongly acts on the gas–liquid interaction when the temperature-dependent properties are considered. Furthermore, the use of literature models and experimental data produces different results, demonstrating the importance of correctly modeling the slag’s thermo-physical properties.

Keywords: rising bubbles; liquid slag

Permalink: https://www.hzdr.de/publications/Publ-32091
Publ.-Id: 32091


Local short-circuits in liquid metal batteries - influence of the contact angle on the droplet movement in VOF-simulations

Benard, S.; Landgraf, S.; Weber, N.; Weier, T.

The presentation will give an overview about Li-droplet formation, as well as their detachment and transport, which finally might lead to a localised short-circuit in liquid metal batteries.

  • Lecture (Conference)
    16th OpenFOAM Workshop 2021, 08.-11.06.2021, Dublin, Ireland

Permalink: https://www.hzdr.de/publications/Publ-32090
Publ.-Id: 32090


Ultrathin Co films with Pt and Au covers - magnetic and structural properties driven by Ga+ ion irradiation

Mazalski, P.; Ohnoutek, L.; Sveklo, I.; Beran, L.; Kurant, Z.; Powroźnik, W.; Wawro, A.; Liedke, M. O.; Butterling, M.; Wagner, A.; Faßbender, J.; Hamrle, J.; Antoš, R.; Kletecka, V.; Veis, M.; Maziewski, A.

The X/Co 3nm/Y (where X, Y=Au, Pt) trilayers with as deposited in-plane magnetization alignment were irradiated with 30 keV Ga+ ions in the wide range of ion fluence. The samples were investigated by means of complementary techniques: magneto-optical magnetometry and spectroscopy (in the photon energy range from 1.2 eV to 4.5 eV), magnetic force microscopy, positron annihilation spectroscopy, X-ray diffraction and reflectivity. Difference in miscibility of interface atoms is clearly manifested in various intermixing extent at Co/Pt and Co/Au interfaces and consequently in magnetic properties of the irradiated trilayers. Low irradiation fluence (~1014 ions/cm2) leads to ~1nm interfaces broadening without visible surface etching for all samples, which is related with a distinct drop of magnetic anisotropy. However, the high irradiation fluence (~5·1015 ions/cm2) results in enhanced interface broadening and significant surface etching (~5 nm) partially removing also Co atoms. Tensile strains (up to 0.5%) were developed in the cover layers. The tensile strain, layers intermixing and the creation of Co-Pt(Au) alloys with different composition formed by irradiation are correlated with the increase of magnetic anisotropy. Moreover it was observed that substitution of Au instead of Pt (as a cap or buffer layer) results in substantial increase of perpendicular magnetic anisotropy. Maximal increase of magnetooptical parameters was observed for Pt/Co/Pt layer. Irradiation induced changes of concentration profiles are revealed using magnetooptical spectra, X-ray reflectivity spectra and simulations with use of binary collision approximation.

Keywords: perpendicular magnetic anisotropy; ion irradiation; positron annihilation spectroscopy; magneto-optical Kerr spectroscopy; molecular beam epitaxy

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Permalink: https://www.hzdr.de/publications/Publ-32089
Publ.-Id: 32089


Thermoelectric Performance of the Half-Heusler Phases RNiSb (R = Sc, Dy, Er, Tm, Lu): High Mobility Ratio between Majority and Minority Charge Carriers

Ciesielski, K.; Synoradzki, K.; Veremchuk, I.; Skokowski, P.; Szymanski, D.; Grin, Y.; Kaczorowski, D.

Deeper understanding of electrical and thermal transport is critical for further development of thermoelectric materials. Here we describe the thermoelectric performance of a group of rare-earth-bearing half-Heusler phases determined in a wide temperature range. Polycrystalline samples of ScNiSb, DyNiSb, ErNiSb, TmNiSb, and LuNiSb are synthesized by arc melting and densified by spark plasma sintering. They are characterized by powder x-ray diffraction and scanning electron microscopy. The physical properties are studied by means of heat-capacity and Hall-effect measurements performed in the temperature range from 2 to 300 K, as well as electrical-resistivity, Seebeck-coefficient, and thermal-conductivity measurements performed in the temperature range from 2 to 950 K. All the materials except TmNiSb are found to be narrow-gap intrinsic p-type semiconductors with rather light charge carriers. In TmNiSb, the presence of heavy holes with large weighted mobility is evidenced by the highest power factor among the series (17 mu W K-²cm(-¹) at 700 K). The experimental electronic relaxation time calculated with the parabolic band formalism is found to range from 0.8 x 10(-¹⁴) to 2.8 x 10(-¹⁴) s. In all the materials studied, the thermal conductivity is between 3 and 6 W m(-¹) K-¹ near room temperature (i.e., smaller than in other pristine d-electron half-Heusler phases reported in the literature). The experimental observation of the reduced thermal conductivity appears fully consistent with the estimated low sound velocity as well as strong point-defect scattering revealed by Debye-Callaway modeling. Furthermore, analysis of the bipolar contribution to the measured thermal conductivity yields abnormally large differences between the mobilities of n-type and p-type carriers. The latter feature makes the compounds examined excellent candidates for further optimization of their thermoelectric performance via electron doping.

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Permalink: https://www.hzdr.de/publications/Publ-32088
Publ.-Id: 32088


Discovery of high-performance thermoelectric copper chalcogenide using modified diffusion-couple high-throughput synthesis and automated histogram analysis technique

Deng, T.; Xing, T.; Brod, M. K.; Sheng, Y.; Qiu, P.; Veremchuk, I.; Song, Q.; Wei, T.-R.; Yang, J.; Snyder, G. J.; Grin, Y.; Chen, L.; Shi, X.

Discovery of novel high-performance materials with earth-abundant and environmentally friendly elements is a key task for civil applications based on advanced thermoelectric technology. Advancements in this area are greatly limited by the traditional trial-and-error method, which is both time-consuming and expensive. The materials genome initiative can provide a powerful strategy to screen for potential novel materials using high-throughput calculations, materials characterization, and synthesis. In this study, we developed a modified diffusion-couple high-throughput synthesis method and an automated histogram analysis technique to quickly screen high-performance copper chalcogenide thermoelectric materials, which has been well demonstrated in the ternary Cu-Sn-S compounds. A new copper chalcogenide with the composition of Cu₇Sn₃S₁₀ was discovered. Studies on crystal structure, band gap, and electrical and thermal transport properties were performed to show that it is a promising thermoelectric material with ultralow lattice thermal conductivity, moderate band gap, and decent electrical conductivity. Via Cl doping, the thermoelectric dimensionless figure of merit zT reaches 0.8 at 750 K, being among the highest values reported in Cu-Sn-S ternary materials. The modified diffusion-couple high-throughput synthesis method and automated histogram analysis technique developed in this study also shed light on the development of other advanced thermoelectric and functional materials.

Keywords: ultralow thermal conductivity; ternary; scattering; sulfides; Cu₂SnS₃; model

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Permalink: https://www.hzdr.de/publications/Publ-32087
Publ.-Id: 32087


Robust Fermi-Surface Morphology of CeRhIn5 across the Putative Field-Induced Quantum Critical Point

Mishra, S.; Hornung, J.; Raba, M.; Klotz, J.; Förster, T.; Harima, H.; Aoki, D.; Wosnitza, J.; McCollam, A.; Sheikin, I.

We report a comprehensive de Haas–van Alphen (dHvA) study of the heavy-fermion material CeRhIn5 in magnetic fields up to 70 T. Several dHvA frequencies gradually emerge at high fields as a result of magnetic breakdown. Among them is the thermodynamically important β1 branch, which has not been observed so far. Comparison of our angle-dependent dHvA spectra with those of the non-4f compound LaRhIn5 and with band-structure calculations evidences that the Ce 4f electrons in CeRhIn5 remain localized over the whole field range. This rules out any significant Fermi-surface reconstruction, either at the suggested nematic phase transition at B* ≈ 30 T or at the putative quantum critical point at Bc ≃ 50 T. Our results rather demonstrate the robustness of the Fermi surface and the localized nature of the 4f electrons inside and outside of the antiferromagnetic phase.

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Permalink: https://www.hzdr.de/publications/Publ-32086
Publ.-Id: 32086


Can microorganisms significantly influence cast iron corrosion in a DGR?

Matschiavelli, N.; Sushko, V.; Dressler, M.; Neubert, T.; Kühn, L.; Schierz, A.; Cherkouk, A.

For the safe storage of high-level radioactive waste (HLW) in deep geological repositories (DGR), several metals could potentially act as canister material and are under investigation with respect to their properties under disposal-relevant conditions. An essential requirement for the selected metal(s) is the long-term stability which is mainly realized by the resistance to corrosion. The process of corrosion depends on the overall environment in the surrounding of the metal canister and which will change over time. Here, parameters like redox potential, pH, the presence of (pore-) water, the salinity and also the presence of metabolically active microorganisms are of relevance, among others. In order to analyze the influence of different pore waters and the natural microbial community of a Bavarian bentonite, which acts as geotechnical barrier and will be in direct contact to the canister, microcosm experiments were set up. These slurry experiments contained B25 bentonite, synthetic Opalinus Clay pore water or saline cap rock solution as well as copper- or cast iron plates in various combinations. During an incubation time of 400 days under anaerobic conditions at 37 °C, several bio-geochemical parameters (e.g. pH, redox potential and the concentration of minerals, sulfate, iron(II/III) and organic acids) were analyzed as well as the corrosion process and a potential microbial influence. The obtained results provide insights into the complex interplay between bentonite, pore water, metals and microorganisms. Different precipitates like carbonates, iron oxides and sulfides were identified on the cast iron surface, potentially accelerating or slowing down the corrosion process and, thus, affecting the long-term stability of the metal canister in a DGR.

  • Lecture (Conference) (Online presentation)
    EGU 2021 General Assembly, 19.-30.04.2021, Wien, Österreich

Permalink: https://www.hzdr.de/publications/Publ-32085
Publ.-Id: 32085


Magnetoelastic study on the frustrated quasi-one-dimensional spin-1/2 magnet LiCuVO4

Miyata, A.; Hikihara, T.; Furukawa, S.; Kremer, R. K.; Zherlitsyn, S.; Wosnitza, J.

We investigated the magnetoelastic properties of the quasi-one-dimensional spin-1/2 frustrated magnet LiCuVO4. Longitudinal-magnetostriction experiments were performed at 1.5 K in high magnetic fields of up to 60 T applied along the b axis, i.e., the spin-chain direction. The magnetostriction data qualitatively resemble the magnetization results, and saturate at Hsat ≈ 54 T, with a relative change in sample length of ΔL/L ≈ 1.8 × 10−4. Remarkably, both the magnetostriction and the magnetization evolve gradually between Hc3 ≈ 48 T and Hsat, indicating that the two quantities consistently detect the spin-nematic phase just below the saturation. Numerical analyses for a weakly coupled spin-chain model reveal that the observed magnetostriction can overall be understood within an exchange-striction mechanism. Small deviations found may indicate nontrivial changes in local correlations associated with the field-induced phase transitions.

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Permalink: https://www.hzdr.de/publications/Publ-32083
Publ.-Id: 32083


Advanced mineral exploration in the glaciated terrain using topsoil geochemistry and the compositional statistical data analysis

Sarala, P.; Pospiech, S.; Middleton, M.; Taivalkoski, A.; Hulkki, H.

Mineral exploration in northern, vulnerable nature areas demands on the development of new, environmentally friendly sampling and analyses techniques. Those areas are typically covered by the transported cover of which the glacigenic sediments such as a till are the most dominant as a result of several glaciation stages. To avoid conventional basal till and bedrock sampling using heavy machines, the use of different surface geochemical sampling media and techniques have increased recently. Particularly, the development of selective and weak leach techniques for the topsoil (Ah and B horizons) geochemistry has been intensive, and the use of those techniques has led to the observation of new mineralization.
In this research, carried out under the project New Exploration Technologies (NEXT), funded by the European Union’s Horizon 2020 research and innovation programme, we used stratified random sampling strategy for creating a sampling grid and developed novel compositional statistical data analysis for the interpretation of geochemical data obtained by the multi-source surface geochemical techniques. The test area located in northern Finland where there is an active exploration campaign going on for Au-U-Co mineralizations in the Rajapalot area, Ylitornio by the Mawson Oy. Glacial morphology in the study area is dominated by the ribbed moraine ridges with peatlands in between. The thickness of till cover varied from some metres to 15 m. A sampling network for both the Ah and B horizon samples comprised 98 proper and 10 field duplicate sampling stations from the mineral soil dominated by the Podsol-type soil horizon. The chemical analyses methods used were Ultratrace 1:1:1 Aqua Regia leach and 0.1 M sodium pyrophosphate leach for the Ah horizon samples, and Ionic leach and Super Trace Aqua Regia leach methods for the B horizon samples. The laboratory analyses were supported by the portable X-Ray Fluorescence (pXRF) analyses done directly in the field. The statistical analysis methods of the results were based on conventional supervised and unsupervised classification techniques using as explanatory variables: a) log-ratio transformations of the geochemical compositions, b) enrichment factors between sampled media, and c) the summaries of the two preceding systems of variables provided by the parallel principal component analysis.
The preliminary results of the topsoil geochemistry show a significant response to many elements to known geochemical features and elevated contents in the base-of-till and underlying bedrock geochemical data. Anomaly patterns are also reflecting the lithological variations of the rock units in the bedrock. Based on the results, it is obvious that a) there is good correlation between the surface geochemistry and underlying bedrock, b) stratified randomization in the planning phase and statistical methods in data interpretation stage increases the quality of the data and the reliability of geochemical exploration, and c) topsoil sampling with selective analysis methods is effective and environmentally friendly geochemical exploration technique in the glaciated terrains.

Keywords: soil; mineral exploration

Permalink: https://www.hzdr.de/publications/Publ-32082
Publ.-Id: 32082


Snow as proxy for mineral exploration – a case study from Northern Finland

Pospiech, S.; Taivalkoski, A.; Lahaye, Y.; Sarala, P.; Kinnunen, J.; Middleton, M.

Modern mineral exploration techniques for Europe are required to be sustainable, environmental friendly and social acceptable. Especially for the geochemical exploration of the ecologically sensitive areas of northern Europe this poses a challenge, because any heavy machinery or invasive methods might cause long-lasting damage to the natural systems. One way of reducing the impact of mineral exploration on the environment during early stages of the exploration is to use surface media, such as upper soil horizons, water, plants and snow. Of these options, snow has several advantages: Sampling and analysing snow is fast and low in costs, it has no impact on the environment, and it is (in winter time) ubiquitous, i.e. available independent of land cover and environment.
In the “New Exploration Technologies (NEXT)” project, funded by the European Union’s Horizon 2020 research and innovation programme, 171 snow samples and 13 field duplicate snow samples for quality control, were collected in March-April 2019 to strengthen the idea of using snow as a sampling material for mineral exploration. The Rajapalot Au-Co prospect in northern Finland, 60 km west from Rovaniemi and operated by Mawson Oy, was selected as a test site. Stratified random sampling was used to create the uneven sampling net over the test area. The samples were analysed at GTK using a Nu AttoM single collector inductively coupled plasma mass spectrometry (SC-ICPMS) which returned analytical results for 52 elements at the ppt level. Due to strict quality control, only Ba, Ca, Cr, Cs, Ga, Li, Mg, Rb, Sb, Sr, Tk, V and Zn passed and were used in the final data analysis.
The preliminary results based on PCA show a strong dependency of snow composition on the soil type. That is, there is a difference if the snow sample was taken above mineral soil or organic soil. Thus, the soil type should be included in the models or the data analysis should be looked separately for different soil types. The linear model predictions were used to test if the snow geochemistry can predict the bedrock geochemistry. For Al, Ca, Li, Sr and Na the prediction works well. Instead of using snow directly for detecting the mineralization for pinpointing drill targets for exploration purposes, snow geochemistry could be used as a lithogeochemical mapping tool to delineate the areas where to continue exploration with more sensitive methods.

Keywords: snow; mineral exploration; compositional data; environmental friendly; sustainable; NEXT

  • Lecture (Conference) (Online presentation)
    EGU General Assembly 2021, 19.-30.04.2021, online, Austria

Permalink: https://www.hzdr.de/publications/Publ-32081
Publ.-Id: 32081


Tuning of ferromagnetic behavior of GaN films by N ion implantation: an experimental and first principle-based study

Singh, P.; Ghosh, S.; Mishra, V.; Barman, S.; Barman, S. R.; Singh, A.; Kumar, S.; Li, Z.; Kentsch, U.; Srivastava, P.

Magnetic properties of N-ion implanted GaN films (150 nm) have been reported. It is found that GaN films grown by the MOCVD technique show strong room temperature ferromagnetic behavior, which can be tuned by implanting N-ions at different fluences (1×10¹⁵ to 5×10¹⁶ ions- cm⁻²). Presence of implanted N at interstitial sites of the GaN host matrix is indicated from the strain observed in GaN by analysis of XRD data. PL spectra show presence of different types of defects in the as deposited film and engineering of defects after N-ion implantation. XPS spectra of Ga 3d-core level and valence band reveal the bonding of implanted N with the host Ga and/or N. The origin of ferromagnetic behavior is ascribed to unpaired electrons created at N sites due to Ga vacancies. First principle-based calculations also confirm ferromagnetism due to Ga vacancies and the reduction of magnetic behavior in Ga deficient GaN with N-ion implantation at interstitial site. The systematic reduction in the saturation magnetic moment value after N-ion implantation is explained on the basis of pairing of the unpaired electrons due to the bond formation of interstitial N with Ga and N present in the host matrix.

Keywords: ion implantation; defects; ferromagnetism; nitrogen interstitials; tuning

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Permalink: https://www.hzdr.de/publications/Publ-32080
Publ.-Id: 32080


Magnetic Refrigeration: From material to application

Gottschall, T.

es hat kein aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences)
    31. Edgar Lüscher Seminar, 09.02.2020, Klosters, Schweiz

Permalink: https://www.hzdr.de/publications/Publ-32079
Publ.-Id: 32079


Recent progress and future projects at HLD and LNCMI - Toulouse

Miyata, A.

es hat kein aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences) (Online presentation)
    The 16th Japanese High Magnetic Field Forum, 03.12.2020, Tuhoku, Japan

Permalink: https://www.hzdr.de/publications/Publ-32078
Publ.-Id: 32078


Variable relative biological effectiveness (RBE) in proton therapy of gliomas

Eulitz, J.; Raschke, F.; Seidlitz, A.; Hahn, C.; Permatassari, F.; Lutz, B.; Schulz, E.; Karpowitz, C.; Grey, A.; Engellandt, K.; Löck, S.; Troost, E. G. C.; Krause, M.; Lühr, A.

Purpose:

Currently, there is an intense debate on the need to consider variable clinical relative biological effectiveness (RBE) in proton therapy. Here, the variability of the clinical RBE is studied for late radiation-induced brain injuries (RIBI) observed after proton therapy in WHO grade 2-3 glioma patients.

Methods: In total, 42 patients out of a consecutive WHO grade 2-3 glioma patient cohort that received (adjuvant) proton radio(chemo)therapy between 2014 and 2017, were eligible for analysis. RIBI lesions (symptomatic or clinically silent) were diagnosed and delineated on T1-weighted magnetic resonance imaging with contrast agent scans obtained in the first two years of follow-up. Correlation of RIBI location and occurrence with simulated dose (D), proton linear energy transfer (LET, dose-averaged) and variable RBE dose parameters were tested in voxel- and in patient-wise logistic regression analyses, respectively. Additionally, anatomical and clinical parameters were considered and model performance was estimated through cross-validated area-under-the-curve (AUC) values.

Results: In 23 patients, 69 RIBI lesions were diagnosed. RIBI location and occurrence were significantly correlated with D×LET and variable RBE dose in voxel- and patient-wise regression analysis with cross-validated AUC values of 0.90 (95% confidence interval: 0.90-0.90) and 0.83 (0.60-1.00), respectively, when incorporating the periventricular region and tumor histology in the analysis. Models without D×LET and constant RBE revealed AUC values of 0.88 (0.88-0.88) and 0.78 (0.51-1.00), respectively.

Conclusions: Models with variable RBE performed substantially better in predicting occurrence and location of RIBI when compared to fixed RBE models. The obtained clinical evidence for a variable proton RBE suggests its consideration in proton treatment planning of brain tumors.

Keywords: Variable proton RBE; Glioma; Radiation-induced brain injury; Periventricular region; LET

  • Invited lecture (Conferences) (Online presentation)
    59th Annual Conference of the Particle Therapy Co-Operative Group, 04.-07.06.2021, Dresden (Online), Germany

Permalink: https://www.hzdr.de/publications/Publ-32077
Publ.-Id: 32077


Magnetoelastic coupling in frustrated magnets: The cases of LiCuVO4 and MnCr2S4

Miyata, A.

es hat kein aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences) (Online presentation)
    ARHMF 2020 and KINKEN Materials Science School 2020 for Young Scientists, 02.12.2020, Tohoku, Japan

Permalink: https://www.hzdr.de/publications/Publ-32076
Publ.-Id: 32076


Pressure-tuned magnetic interactions in the triangular-lattice Quantum antiferromagnet Cs2CuCl4

Zvyagin, S.

es hat kein aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences) (Online presentation)
    ARHMF 2020 and KINKEN Materials Science School 2020 for Young Scientists, 01.-03.12.2020, Tohoku, Japan

Permalink: https://www.hzdr.de/publications/Publ-32075
Publ.-Id: 32075


Contactless generation of cavitation in high temperature liquid metals and its impact on particle dispersion in solidified iron and steel samples

Sarma, M.; Grants, I.; Herrmannsdörfer, T.; Gerbeth, G.

A recently developed method for the contactless magnetic generation of cavitation is demonstrated for high-melting-point metals. The approach is based on the floating-zone technique, which is truly contactless and crucible-free as it uses electromagnetic forces. Using this method, ultra-high-temperature ceramic particles, such as TiN, TiB₂ and TiC, are admixed in liquid iron and 316L steel. The dispersion and particle refinement caused by cavitation treatment during melting and solidification are investigated. Magnetic fields up to 8 T that correspond to pressure oscillation amplitude of 0.83 MPa are used. The signal emitted by the collapsing bubbles is captured and visualized for iron melts. Samples with a higher number of cavitation nuclei exhibit a more stable cavitation response. Improved reinforcement refinement is demonstrated for increasing cavitation intensity – the size of precipitates is evidently reduced due to the cavitation
treatment.

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Permalink: https://www.hzdr.de/publications/Publ-32074
Publ.-Id: 32074


Pages: [1.] [2.] [3.] [4.] [5.] [6.] [7.] [8.] [9.] [10.] [11.] [12.] [13.] [14.] [15.] [16.] [17.] [18.] [19.] [20.] [21.] [22.] [23.] [24.] [25.] [26.] [27.] [28.] [29.] [30.] [31.] [32.] [33.] [34.] [35.] [36.] [37.] [38.] [39.] [40.] [41.] [42.] [43.] [44.] [45.] [46.] [47.] [48.] [49.] [50.] [51.] [52.] [53.] [54.] [55.] [56.] [57.] [58.] [59.] [60.] [61.] [62.] [63.] [64.] [65.] [66.] [67.] [68.] [69.] [70.] [71.] [72.] [73.] [74.] [75.] [76.] [77.] [78.] [79.] [80.] [81.] [82.] [83.] [84.] [85.] [86.] [87.] [88.] [89.] [90.] [91.] [92.] [93.] [94.] [95.] [96.] [97.] [98.] [99.] [100.] [101.] [102.] [103.] [104.] [105.] [106.] [107.] [108.] [109.] [110.] [111.] [112.] [113.] [114.] [115.] [116.] [117.] [118.] [119.] [120.] [121.] [122.] [123.] [124.] [125.] [126.] [127.] [128.] [129.] [130.] [131.] [132.] [133.] [134.] [135.] [136.] [137.] [138.] [139.] [140.] [141.] [142.] [143.] [144.] [145.] [146.] [147.] [148.] [149.] [150.] [151.] [152.] [153.] [154.] [155.] [156.] [157.] [158.] [159.] [160.] [161.] [162.] [163.] [164.] [165.] [166.] [167.] [168.] [169.] [170.] [171.] [172.] [173.] [174.] [175.] [176.] [177.] [178.] [179.] [180.] [181.] [182.] [183.] [184.] [185.] [186.] [187.] [188.] [189.] [190.] [191.] [192.] [193.] [194.] [195.] [196.] [197.] [198.] [199.] [200.] [201.] [202.] [203.] [204.] [205.] [206.] [207.] [208.] [209.] [210.] [211.] [212.] [213.] [214.] [215.] [216.] [217.] [218.] [219.] [220.] [221.] [222.] [223.] [224.] [225.] [226.] [227.] [228.] [229.] [230.] [231.] [232.] [233.] [234.] [235.] [236.] [237.] [238.] [239.] [240.] [241.] [242.] [243.] [244.] [245.] [246.] [247.] [248.] [249.] [250.] [251.] [252.] [253.] [254.] [255.] [256.] [257.] [258.] [259.] [260.] [261.] [262.] [263.] [264.] [265.] [266.] [267.] [268.] [269.] [270.] [271.] [272.] [273.] [274.] [275.] [276.] [277.] [278.] [279.] [280.] [281.] [282.] [283.] [284.] [285.] [286.] [287.] [288.] [289.] [290.] [291.] [292.] [293.] [294.] [295.] [296.] [297.] [298.] [299.] [300.] [301.] [302.] [303.] [304.] [305.] [306.] [307.] [308.] [309.] [310.] [311.] [312.] [313.] [314.] [315.] [316.] [317.] [318.] [319.] [320.] [321.] [322.] [323.] [324.] [325.] [326.] [327.] [328.] [329.] [330.] [331.] [332.] [333.] [334.] [335.] [336.] [337.] [338.] [339.] [340.] [341.] [342.] [343.] [344.] [345.] [346.] [347.] [348.] [349.]