Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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41397 Publications

Series of Tetravalent Actinide Amidinates: Structure Determination and Bonding Analysis.

Kloditz, R.; Fichter, S.; Kaufmann, S.; Brunner, T. S.; Kaden, P.; Patzschke, M.; Stumpf, T.; Roesky, P. W.; Schmidt, M.; März, J.

NMR spectra for the complex series in the publication together with the xyz coordinates of the optimized complexes. An example input-file for ORCA v4.1.2 for the calculation of the wavefunction used for QTAIM is presented as well.

Keywords: actinides; NMR; DFT; QTAIM; NPA; coordination chemistry; transuranium

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Permalink: https://www.hzdr.de/publications/Publ-31654
Publ.-Id: 31654


Data for: Spectral X-ray Computed Micro Tomography: 3-dimensional chemical imaging

Sittner, J.; Da Assuncao Godinho, J. R.; Renno, A.; Cnudde, V.; Boone, M.; de Schryver, T.; van Loo, D.; Merkulova, M.; Roine, A.; Liipo, J.

The files show the data we used for the publication.

Keywords: X-ray computed tomography; Spectral X-ray tomography; Photon counting detector; 3D imaging

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Permalink: https://www.hzdr.de/publications/Publ-31653
Publ.-Id: 31653


Don't Publish - Previewer test for splitted zip file 23

Gruber, T.
Other: Pape, David

Test if large zip files can be splittet and read by the previewer. Looks like it works.

Keywords: update Keyword

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Permalink: https://www.hzdr.de/publications/Publ-31651
Publ.-Id: 31651


Are two-dimensional materials radiation tolerant?

Krasheninnikov, A.

Two-dimensional (2D) materials have many unique properties, which can be exploited in various applications. In particular, electronic devices based on 2D materials should ideally be suited for the operation in outer cosmic space due to their low weight, small size and low power consump- tion. This brings about the issue of their radiation hardness, or tolerance, which has recently been addressed in a number of studies. The results of these investigations are somewhat counterintu- itive: although one can naively expect that atomically thin structures should easily be destroyed by the beams of energetic particles, the devices made from 2D materials were reported to exhibit extraordinary radiation hardness. In this Focus article, an overview of the recent studies on the subject is given, followed by the discussion of the origin of the reported high tolerance, which is inherently related to the response of 2D materials, the systems with the reduced dimensionality, to irradiation. The analysis of the experimental and theoretical data on the behavior of 2D systems under irradiation indicates that although free-standing 2D materials can indeed be referred to as radiation resilient systems under irradiation conditions corresponding to the outer space, this is generally not the case, as the environment, e.g., the substrate, can strongly influence the radiation tolerance of 2D materials and devices based on these systems.

Keywords: 2D materials; irradiation; radiation tolerance

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Permalink: https://www.hzdr.de/publications/Publ-31650
Publ.-Id: 31650


Influence of chemical zoning on sandstone calcite cement dissolution: The case of manganese and iron

Trindade Pedrosa, E.; Fischer, C.; Morales, L. F.; Rohlfs, R. D.; Luttge, A.

Chemical zoning of crystals is often found in nature. Crystal zoning can play a role in a mineral's thermodynamic stability and in its kinetic response in the presence of fluids. Dissolution experiments at far-from-equilibrium conditions were performed using a sandstone sample containing calcite cement crystal patches. The surface normal retreat of the calcite crystals was obtained by vertical scanning interferometry (VSI) in their natural position in the rock. Dissolution rate maps showed contrasting surface dissolution areas within the crystals, in the same locations where electron microprobe (EMP) maps showed the presence of manganese (Mn) and iron (Fe) substitutions for calcium in the calcite structure. Iron zoning was only identified in combination with manganese. Maximum registered manganese contents were 1.9(9) wt% and iron were 2(1) wt%. Manganese zoning of only 0.9(5) wt% resulted in around 40% lower dissolution rates than the adjacent pure calcite zones. The combination of both Mn and Fe cation substitutions resulted in one order of magnitude lower dissolution rates compared to pure calcite in the same sample. These results show that mineral zoning can significantly affect reaction rates, a parameter that needs better understanding for the improvement of kinetic geochemical models at the pore scale.

Keywords: Sandstone; Calcite; Dissolution; Zoning; Manganese; Iron

Permalink: https://www.hzdr.de/publications/Publ-31649
Publ.-Id: 31649


Dyke apertures record stress accumulation during sustained volcanism

Thiele, S. T.; Cruden, A. R.; Micklethwaite, S.; Köpping, J.; Bunger, A. P.

The feedback between dyke and sill intrusions and the evolution of stresses within volcanic systems is poorly understood, despite its importance for magma transport and volcano instability. Long-lived ocean island volcanoes are crosscut by thousands of dykes, which must be accommodated through a combination of flank slip and visco-elastic deformation. Flank slip is dominant in some volcanoes (e.g., Kilauea), but how intrusions are accommodated in other volcanic systems remains unknown. Here we apply digital mapping techniques to collect > 400,000 orientation and aperture measurements from 519 sheet intrusions within Volcán Taburiente (La Palma, Canary Islands, Spain) and investigate their emplacement and accommodation. We show that vertically ascending dykes were deflected to propagate laterally as they approached the surface of the volcano, forming a radial dyke swarm, and propose a visco-elastic model for their accommodation. Our model reproduces the measured dyke-aperture distribution and predicts that stress accumulates within densely intruded regions of the volcano, blocking subsequent dykes and causing eruptive activity to migrate. These results have significant implications for the organisation of magma transport within volcanic edifices, and the evolution and stability of long-lived volcanic systems.

Permalink: https://www.hzdr.de/publications/Publ-31648
Publ.-Id: 31648


High Performance Computing: ISC High Performance 2020 International Workshops

Jagode, H.; Anzt, H.; Juckeland, G.; Ltaief, H.

This book constitutes the refereed post-conference proceedings of 10 workshops held at the 35th International ISC High Performance 2020 Conference, in Frankfurt, Germany, in June 2020:

First Workshop on Compiler-assisted Correctness Checking and Performance Optimization for HPC (C3PO); First International Workshop on the Application of Machine Learning Techniques to Computational Fluid Dynamics Simulations and Analysis (CFDML); HPC I/O in the Data Center Workshop (HPC-IODC); First Workshop \Machine Learning on HPC Systems" (MLHPCS); First International Workshop on Monitoring and Data Analytics (MODA); 15th Workshop on Virtualization in High-Performance Cloud Computing (VHPC).

The 25 full papers included in this volume were carefully reviewed and selected. They cover all aspects of research, development, and application of large-scale, high performance experimental and commercial systems. Topics include high-performance computing (HPC), computer architecture and hardware, programming models, system software, performance analysis and modeling, compiler analysis and optimization techniques, software sustainability, scientific applications, deep learning.

Keywords: artificial intelligence; computer hardware; computer networks; computer science; computer systems; distributed computer systems; distributed systems; education; HPC; parallel architectures

Permalink: https://www.hzdr.de/publications/Publ-31647
Publ.-Id: 31647


The resource potential of mine waste – More than metal concentrations

Büttner, P.; Nühlen, J.; Engelhardt, J.

In the last decade, several national and European funding programs addressed the resource potential of mine wastes (including tailings and metallurgical slag dumps), with a clear focus on the development of new sources for critical raw materials (CRM). The European Commission defined CRMs as highly important for the European high tech industry. European and national resource strategies refer to this definition and include the development of new CRM sources as one of their main objectives. The German Federal Ministry for Research and Education (BMBF) funded the program “r3 –strategic metals and minerals – innovative technologies for resource efficiency” that started in 2012. The aim of the program was to ensure the domestic supply of strategically significant metals and minerals. Suitable projects had to act in the fields of recycling and substitution of raw materials as well as in the field of reduced material consumption. Urban mining and the evaluation of resource efficiency were further topics that suited the program. The Helmholtz Institute Freiberg for Resource Technology (HIF) and the Fraunhofer Institute for Environmental, Safety, and Energy Technology (UMSICHT) worked already together in different projects about mine waste characterization and resource extraction in r3.
The Helmholtz Institute Freiberg for Resource Technology pursues the objective of developing innovative technologies for the economy so that mineral and metalliferous raw materials become more available, undergo highly efficient processes and recycle in an environmentally
friendly manner. As a part of the national strategy for raw materials in 2011, the German government initiated the HIF. It is a constituent part of the Helmholtz-Zentrum Dresden-Rossendorf and works in close collaboration with TU Bergakademie Freiberg. The HIF is a core member of the European EIT RawMaterials network, having played a decisive role in its establishment. Fraunhofer UMSICHT is a pioneer for sustainable energy and raw materials management by supplying and transferring scientific results into companies, society and politics. The dedicated UMSICHT team researches and develops, together with partners, sustainable products, processes and services. Together with industry and public partners, such as the Geological Survey of Germany (BGR), UMSICHT and HIF founded the r³-mine-waste-cluster in order to determine a realistic mine waste
potential for Germany and give a reliable resource estimation for secondary raw materials. Nowadays, however, there is a political and public interest beyond the potential of valuable metals from mine wastes. After the catastrophic tailings accident in Vales Corrego do Feijão mine, Brazil, the social pressure to lower these risks raised on the mining industry, on the mine waste owners (e.g. states) and on the politics. With the new Global Industry Standard on Tailings Management a new set of guidelines was developed in order to avoid these accidents in the future. “The International Council
on Mining and Metals (ICMM), the United Nations Environment Programme (UNEP) and the Principles for Responsible Investment (PRI) share a commitment to the adoption of global best practices on tailings storage facilities. They have co-convened this global tailings review to establish an international standard.” Their environmental risks and at the same time their high potential as a source for (critical) raw materials make mine waste projects a complex exercise. There is a need for solutions that respect environmental, technical, civil and economic issues and provide holistic and sustainable approaches. In order to validating and adjusting different approaches, the HIF coordinates the recomine-alliance. Local stakeholders representing environmental, technical, scientific, governmental and civil institutions assemble in recomine for a development of holistic mine waste solutions for a worldwide application.

Keywords: re-mining; resources; HIF; tailings; mine waste; mining; CRM; slag dump; mine water; WIR!; r3; recomine; Freiberg; Network; Alliance; BMBF; holistic; remediation; sustainable

  • World of Mining - Surface & Underground 72(2020)5, 264-269
    ISSN: 1613-2408

Permalink: https://www.hzdr.de/publications/Publ-31646
Publ.-Id: 31646


Anode-metal drop formation and detachment mechanisms in liquid metal batteries

Benard, S.; Weber, N.; Horstmann, G. M.; Landgraf, S.; Weier, T.

We study numerically localised short-circuits in Li||Bi liquid metal batteries. In the prototype of a classical, three liquid-layer system, we assume a perceptible local deformation of the Li-salt interface. We find that there exists always a critical current at which a Li-droplet is cut off from this hump, and transferred to the Bi-phase. In a second case, we assume that the molten Li is contained in a metal foam, and that a small Li-droplet emerges below this foam due to insufficient wetting. This droplet is deformed by Lorentz forces, until eventually being pinched off. Here, the critical current is slightly lower than in the three layer system, and both, a droplet transfer and complete short-circuits are observed. Finally, we discuss the relevance of our simulations for experimentally observed short-circuits and non-faradaic Li-transfer.

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Permalink: https://www.hzdr.de/publications/Publ-31645
Publ.-Id: 31645


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

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

Artificial spin ices are periodic arrangements of interacting nanomagnets that have been successfully used to investigate emergent phenomena in the presence of geometric frustration. Recently, it has become clear that artificial spin ices equally have the potential to be used as building blocks for creating functional materials, such as magnonic crystals and ratchets, in addition to supporting a large number of programmable magnetic states. In this context, we investigate the magnetization dynamics in a system exhibiting asymmetric magnetostatic interactions owing to locally broken structural symmetry. We find that this gives rise to a rich spectrum that can be tuned through an external field. We also determine the evolution of the observed excitation modes, starting with building blocks and evolving into larger arrays, highlighting the role of symmetry breaking in defining the mode spectrum of the system. Concurrently, the increasing complexity of the spectrum leads to the existence of a large number of modes over a narrow range of frequencies. These results contribute to the understanding of magnetization dynamics in spin ice systems beyond the kagome and square ice geometries with a view towards the realization of reconfigurable magnonic crystals based on spin ices.

Keywords: artificial spin ice; symmetry breaking; spin-wave dynamics; reconfigurable; magnonic crystal

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Permalink: https://www.hzdr.de/publications/Publ-31644
Publ.-Id: 31644


A FDG-PET radiomics signature detects esophageal squamous cell carcinoma patients who do not benefit from chemoradiation

Li, Y.; Beck, M.; Päßler, T.; Lili, C.; Wu, H.; Ha, D.; Amthauer, H.; Biebl, M.; Thuss-Patience, P.; Berger, J.; Stromberger, C.; Tinhofer, I.; Kruppa, J.; Budach, V.; Hofheinz, F.; Lin, Q.; Zschaeck, S.

Detection of patients with esophageal squamous cell carcinoma (ESCC) who do not benefit from standard chemoradiation (CRT) is an important medical need. Radiomics using 18-fluorodeoxyglucose (FDG) positron emission tomography (PET) is a promising approach. In this retrospective study of 184 patients with locally advanced ESCC. 152 patients from one center were grouped into a training cohort (n = 100) and an internal validation cohort (n = 52). External validation was performed with 32 patients treated at a second center. Primary endpoint was disease-free survival (DFS), secondary endpoints were overall survival (OS) and local control (LC). FDG-PET radiomics features were selected by Lasso-Cox regression analyses and a separate radiomics signature was calculated for each endpoint. In the training cohort radiomics signatures containing up to four PET derived features were able to identify non-responders in regard of all endpoints (DFS p < 0.001, LC p = 0.003, OS p = 0.001). After successful internal validation of the cutoff values generated by the training cohort for DFS (p = 0.025) and OS (p = 0.002), external validation using these cutoffs was successful for DFS (p = 0.002) but not for the other investigated endpoints. These results suggest that pre-treatment FDG-PET features may be useful to detect patients who do not respond to CRT and could benefit from alternative treatment.

Permalink: https://www.hzdr.de/publications/Publ-31643
Publ.-Id: 31643


An Experimental and Numerical Study of Precision Cooling to Determine Minimum Coolant Velocity of Downsized Internal Combustion Engines Using Boiling

Qasemian, A.; Keshavarz, A.; Setoodeh, H.; Mohammadi, A.; Chitsaz, I.

Nowadays, due to the internal combustion engine industry's orientation towards downsizing, modern efficient cooling systems with lower power consumption, small size and high compactness are essential. To improve these items, applying precision cooling and boiling phenomenon are inevitable. Having an appropriate coolant flow velocity which leads to utilize only the advantages of boiling heat transfer has always been a challenge. Two experimental test rigs, one for modeling and accurate prediction of subcooled flow boiling and the other for measurement and validation of coolant velocity in a water jacket by particle image velocimetry method are set up. An accurate and robust empirical correlation for modeling of subcooled flow boiling which occurs in the water jacket is developed. Then, through a three dimensional thermal analysis, the heat transfer parameters such as heat flux and temperature distribution of the internal combustion engine cylinder block and head are obtained numerically. Finally, as the main achievement of this study, a diagram is presented which combines the concept of precision cooling and subcooled flow boiling and gives the minimum coolant velocity in terms of heat flux. Without going into detail thermo-fluids analysis, this provides a convenient tool to determine the minimum velocity of the coolant flow over the different regions of the internal combustion engine water jacket wall to keep it at its allowable temperature range.

Keywords: Internal combustion engine; Downsizing; Heat transfer; Precision cooling; Subcooled flow boiling

Permalink: https://www.hzdr.de/publications/Publ-31642
Publ.-Id: 31642


Dissolution of donor-vacancy clusters in heavily doped n-type germanium

Prucnal, S.; Liedke, M. O.; Wang, X.; Butterling, M.; Posselt, M.; Knoch, J.; Windgassen, H.; Hirschmann, E.; Berencen, Y.; Rebohle, L.; Wang, M.; Napoltani, E.; Frigerio, J.; Ballabio, A.; Isella, G.; Hübner, R.; Wagner, A.; Bracht, H.; Helm, M.; Zhou, S.

The n-type doping of Ge is a self-limiting process due to the formation of vacancy-donor complexes (DnV with n ≤ 4) that deactivate the donors. This work unambiguously demonstrates that the dissolution of the dominating P4V clusters in heavily phosphorus-doped Ge epilayers can be achieved by millisecond-flash lamp annealing at about 1050 K. The P4V cluster dissolution increases the carrier concentration by more than three-fold together with a suppression of phosphorus diffusion. Electrochemical capacitance-voltage measurements in conjunction with secondary ion mass spectrometry, positron annihilation lifetime spectroscopy and theoretical calculations enabled us to address and understand a fundamental problem that has hindered so far the full integration of Ge with complementary-metal-oxide-semiconductor technology.

Keywords: Ge; vacancies; doping; positron annihilation lifetime spectroscopy; flash lamp annealing

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Permalink: https://www.hzdr.de/publications/Publ-31641
Publ.-Id: 31641


A new research infrastructure for investigating flow hydraulics and process equipment at critical fluid properties

Windmeier, C.; Flegiel, F.; Döß, A.; Franz, R.; Schleicher, E.; Wiezorek, M.; Schubert, M.; Hampel, U.

An optimized equipment design for natural gas processing and liquefaction plants becomes increasingly difficult with changing process conditions: Particularly low values of surface tension create rising challenges on the design of phase separators and column internals. The TERESA test rig at HZDR was designed to allow the investigation of multi-phase thermohydraulics and phase separator performance under critical fluid properties in industrial dimensions. A versatile pipe test section is available in DN200 and equipment internals may be tested in a sectional DN300/DN500 test separator. The applied test fluid shows a high vapor-liquid density difference between 1470 and 940 kg/m³, viscosity as low as 0.12 mm²/s, and surface tension down to 1.3 mN/m. Volumetric liquid and vapor flow rates may be varied up to 9 and 530 m³/h in the test rig, respectively.

Keywords: critical fluid properties; hydraulics; phase separation; two-phase flow

Permalink: https://www.hzdr.de/publications/Publ-31640
Publ.-Id: 31640


The GeDI project-a German DIBH database

Duma, M. N.; Krause, M.; Hoinkis, C.; Gurtner, K.; Richter, C.; Corradini, S.; Pazos, M. E.; Schoencker, S.; Walke, M.; Gabriel, C.; Brunner, T.; Krug, D.; Hoerner-Rieber, J.; Grosu, A. L.; Nicolay, N. H.; Wittig, A.

Background: Studies indicate that all left-sided breast cancer patients benefit from the deep inspiration breath hold technique (DIBH), however, not all patients experience the same benefit. A meta-analysis performed by Latty et al. reviewed 18 studies evaluating DIBH, which demonstrated a relative reduction of mean dose (Dmean) to the heart ranging from 26.2% to 75% as compared to irradiation in free breathing. However, as most papers report averages rather than patient-by-patient analyses, outliers remain unidentified. Thus, a lack of data and knowledge exists in determining selection criteria to predict individual patient benefit from DIBH.

Methods: We are planning to establish a large retrospective database of breast cancer patients treated with deep inspiration breath hold (DIBH) radiotherapy techniques. Data will be collected anonymized from all participating centres. A detailed analysis of:

1. Differences in OAR sparing by anatomical conditions
2. Differences in OAR sparing by used DIBH techniques (free breathing, RPM, surface scanning with camera or laser systems etc)
3. Differences in OAR sparing by fractionation schedules (normalized to EQD2)
4. Differences in OAR sparing by PTV volumes and CTV definitions

but not limited to, will be performed.

Discussion: Patient data will be stratified according to different anatomical conditions (such as large breasts vs. small breasts), radiation techniques, fractionation schedules and PTV volumes (for e.g. chest wall after mastectomy vs. breast only vs. breast and lymphatics etc). This multicentre database will allow for the first time an in depth analysis of the impact of DIBH. It will enhance our knowledge on outliers and will provide selection criteria to predict individual patient benefit from DIBH.

  • Lecture (Conference) (Online presentation)
    DEGRO, 24.-28.06.2020, Wiesbaden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-31639
Publ.-Id: 31639


Magnetic-field-assisted electrodeposition of metal to obtain conically structured ferromagnetic layers

Huang, M.; Eckert, K.; Mutschke, G.

Micro- or nano-structured ferromagnetic layers often possess superior electrocatalytic properties but are difficult to manufacture in general. The present work investigates how a magnetic field can possibly support local cone growth on a planar electrode during electrodeposition, thus simplifying fabrication. Analytical and numerical studies were performed on conical structures of mm size to elaborate the influence of the magnetic forces caused by an electrode-normal external field. It is shown that, beside the Lorentz force studied earlier in the case of single cones [1], the magnetic gradient force enabled by the field alteration near the ferromagnetic cathode significantly supports cone growth. Detailed studies performed for sharp and flat single cones allow conclusions to be drawn on the support at different stages in the evolution of conical deformations. Furthermore, the influence from neighboring cones is studied with arrays of cones at varying distances apart. Nearby neighbors generally tend to mitigate the flow driven by the magnetic forces. Here, the support for cone growth originating from the magnetic gradient force is less heavily affected than that from the Lorentz force. Our results clearly show that the magnetic field has a beneficial effect on the growth of ferromagnetic conical structures, which could also be useful on the micro- and nanometer scales.

Keywords: metal electrodeposition; magnetic field; surface-structured electrode; Lorentz force; magnetic gradient force; numerical simulation

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Permalink: https://www.hzdr.de/publications/Publ-31638
Publ.-Id: 31638


Capacity and sizing of wire mesh mist eliminators at critical fluid properties

Flegiel, F.; Windmeier, C.; Wiezorek, M.; Döß, A.; Schubert, M.; Hampel, U.; Schleicher, E.

Wire mesh flooding point measurements at low surface tension < 10 mN m-1 were conducted using a refrigerant as model fluid. A new method for the calculation of wire mesh capacity was developed based on experimental data from literature and data from this study. In comparison to the well-known and widely adapted K-value method given in the Gas Processors Suppliers Association (GPSA) Engineering Databook and various other sources, the new method yields 3-38 % reduced wire mesh cross-sections for fluid systems at pressures above 20 bar(g) while retaining an inherent safety margin.

Keywords: flooding point; K-value; wire-mesh; mist eliminator capacity

Permalink: https://www.hzdr.de/publications/Publ-31637
Publ.-Id: 31637


Morphology of flashing feeds at critical fluid properties in larger pipes

Döß, A.; Schubert, M.; Wiezorek, M.; Hampel, U.; Flegiel, F.; Windmeier, C.; Schleicher, E.; Schunk, C.

Tailored conditioning and control of flashing feeds in industrial applications requires knowledge of the evolving flow morphology and phase fractions along the feed pipe. Design methods obtained from reference systems (e.g. water/air) are hardly applicable for commercial scales and critical fluid properties (e.g. high vapor densities, low surface tension). In this study, the flow morphology of flashing feeds in a novel refrigerant test rig at critical fluid properties was analyzed using wire-mesh sensors at two locations along the feed pipe and experimental data from the water/air system.

Keywords: Flashing feed; Refrigerant cycle process; Two-phase flow morpholog; Wire-mesh sensor

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Permalink: https://www.hzdr.de/publications/Publ-31636
Publ.-Id: 31636


Vortrag der Gleichstellungsbeauftragten des HZDR vor dem AGBR

Fiedler, F.

Vortrag der GSB vor dem AGBR

  • Lecture (others) (Online presentation)
    Treffen des AGBR, 27.10.2020, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-31635
Publ.-Id: 31635


Two-phase flow morphology and phase fractions in larger feed line sections

Döß, A.; Schubert, M.; Hampel, U.; Mehringer, C.; Geipel, C.; Schleicher, E.

The design of industrial feed line sections and the selection of appropriate inlet devices requires knowledge about the two-phase flow morphology and phase fractions in order to reduce costly overdesign. Since experimental data for two-phase pipe flows at industrial scale are hardly available, current prediction methods are subject to high unertainities. In this study, horizontal two-phase flow morphologies for different industrial feed line sections were studied using wire-mesh sensors at multiple locations along the pipe. The obtained phase fraction data are compared with correlations.

Keywords: Feed section; Flow morphology; Horizontal bend; Two-phase flow; Wire-mesh sensor

Permalink: https://www.hzdr.de/publications/Publ-31634
Publ.-Id: 31634


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

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

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

Keywords: Electron Flash effect; Oxygen depletion; Normal tissue toxicity; Zebrafish embryo

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Permalink: https://www.hzdr.de/publications/Publ-31633
Publ.-Id: 31633


Experience with the Sperradiant THz user Facility Driven by a Quasi-CW SRF Accelerator at ELBE

Bawatna, M.; Green, B. W.

Instabilities in beam and bunch parameters, such as bunch charge, beam energy, or changes in the phase or amplitude of the accelerating field in the RF cavities can be the source of noise in the various secondary sources driven by the electron beam. Bunch charge fluctuations lead to in-tensity instabilities in the superradiant THz sources. The primary electron beam driving the light sources has a maximum energy of 40 MeV and a maximum current of 1.6 mA. Depending on the mode of operation required, there are two available injectors in use at ELBE. The first is the thermionic injector, which is used for regular operating modes and supports repetition rates up to 13 MHz and bunch charges up to 100 pC. The second is the SRF photo-cathode injector, which is used for experiments that may require lower emittance or higher bunch charges of up to 1 nC. It has a maximum repetition rate of 13 MHz, which can be adjusted to lower rates if desired, also including different macro pulse modes of operation. In this contribution, we will present our work in the pulse-resolved intensity measurement that allows for the correction of intensity instabilities.

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  • Open Access Logo Contribution to proceedings
    FEL2019 - 39th International Free-Electron Laser Conference, 26.-30.08.2019, Hamburg, Germany
    Proceedings of the 39th International Free-Electron Laser Conference: JACoW, 978-3-95450-210-3
    DOI: 10.18429/JACoW-FEL2019-TUP007

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Permalink: https://www.hzdr.de/publications/Publ-31632
Publ.-Id: 31632


Data for: Scanning transmission imaging in the helium ion microscope using a microchannel plate with a delay line detector

Serralta Hurtado De Menezes, E.; Klingner, N.; de Castro, O.; Mousley, M.; Eswara, S.; Duarte Pinto, S.; Wirtz, T.; Hlawacek, G.

  A detection system based on a microchannel plate with a delay line readout structure has been developed to perform scanning transmission ion microscopy (STIM) in the helium ion microscope (HIM). This system is an improvement over other existing approaches since it combines the information of the scanning beam position on the sample with the position (scattering angle) and time of the transmission events. Various imaging modes such as bright and dark field or the direct image of the transmitted signal can be created by post-processing the collected STIM data. Furthermore, the detector has high spatial and time resolution, is sensitive to both ions and neutral particles over a wide energy range, and shows robustness against ion beam-induced damage. A special in-vacuum movable support gives the possibility of moving the detector vertically, placing the detector closer to the sample for the detection of high-angle scattering events, or moving it down to increase the angular resolution and distance for time-of-flight measurements. With this new system, we show composition-dependent contrast for amorphous materials and the contrast difference between small and high angle scattering signals. We also detect channeling related contrast on polycrystalline silicon, thallium chloride nanocrystals, and single crystalline silicon by comparing the signal transmitted at different directions for the same data set.

Keywords: helium ion microscopy; scanning transmission ion microscopy; delay line detector; channeling; bright field; dark field

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Permalink: https://www.hzdr.de/publications/Publ-31631
Publ.-Id: 31631


A new approach for determining tray and point efficiencies via revamping of hydraulic air/water column mockups

Marchini, S.; Vishwakarma, V.; Schubert, M.; Brunazzi, E.; Hampel, U.

Tray and point efficiencies are the key parameters for characterizing the performance of a distillation tray.
The tray efficiencies are experimentally determined mostly by sampling the incoming and exiting streams of liquid and gas over the tray. Contrarily, the point efficiency determination is technically challenging and thus, it is derived mainly from correlations or small-scale experiments. Only few studies on the experimental determination of point efficiencies on large-scale distillation trays exist. However, the traditional physical systems pose several technical restrictions and safety concerns that often prevent their integration with the available air/water column mockups.
In this study, the stripping of isobutyl acetate from an aqueous solution using air is proposed as a physical system. It offers several advantages over the traditional ones (in terms of adaptability to different gas and liquid flow rates, safety and minimum revamping requirements), and is proved suitable for being readily integrated into existing cold fluid air/water mockups without any major modification.
The liquid concentration distribution on an 800 mm dia. distillation sieve tray was investigated by sampling the liquid at different deck locations for subsequent UV-spectroscopy. The concentration distribution was used to obtain the point efficiency values accounting for both axial and transverse liquid mixing on the tray. The concentration distributions, tray and point efficiency values obtained for different weir loads showed good agreement with the predictions given by the correlations and models used in the literature. The proposed approach can also account for the effect of weeping on the tray efficiency.
Potential future application of the proposed approach can address the investigation and design of novel tray concepts (e.g. with liquid flow conditioners), the development and validation of point and tray efficiency models as well as the validation of CFD simulations.

Keywords: tray efficiency; point efficiency; isobutyl acetate stripping; tray column; sieve tray; mockup revamp; weeping

  • Contribution to proceedings
    Jahrestreffen der ProcessNet-Fachgruppen Fluidverfahrenstechnik und Wärme- und Stoffübertragung, 24.-26.02.2021, Leipzig, Germany

Permalink: https://www.hzdr.de/publications/Publ-31630
Publ.-Id: 31630


Negative resistance for colloids driven over two barriers in a microchannel

Zimmermann, U.; Löwen, H.; Kreuter, C.; Erbe, A.; Leiderer, P.; Smallenburg, F.

When considering the flow of currents through obstacles, one core expectation is that the total resis- tance of sequential single resistors is additive. While this rule is most commonly applied to electronic circuits, it also applies to other transport phenomena such as the flow of colloids or nanoparti- cles through channels containing multiple obstacles, as long as these obstacles are sufficiently far apart. Here we explore the breakdown of this additivity for fluids of repulsive colloids driven over two energetic barriers in a microchannel, using real-space microscopy experiments, particle-resolved simulations, and dynamical density functional theory. If the barrier separation is comparable to the particle correlation length, the resistance is highly non-additive, such that the resistance added by the second barrier can be significantly higher or lower than that of the first. Surprisingly, in some cases the second barrier can even add a negative resistance, such that two identical barriers are easier to cross than a single one. We explain this counterintuitive observation in terms of the structuring of particles trapped between the barriers.

Keywords: colloidal model systems; soft matter; transport phenomena

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Permalink: https://www.hzdr.de/publications/Publ-31629
Publ.-Id: 31629


Metal Pad Roll Instability at Room Temperature Using Pairs of Liquid Metals

Herreman, W.; Nore, C.; Cappanera, L.; Guermond, J.-L.; Weier, T.

Metal pad roll instability is a well known phenomenon that occurs in aluminium reduction cells [1] Since long, scientists and engineers have been searching for an experimental model that recreates the metal pad roll instability in a well controlled laboratory environment. [2] partly succeeded in this task by using GaInSn eutectic alloy in replacement of aluminium and a steel wire array, in replacement of the badly conducting cryolite layer. A rolling wave motion was observed but comparison to fluid based theoretical models remains difficult.
In this talk, we demonstrate that it is possible to observe metal pad roll instability in a centimeter scale cylindrical set-up at room temperature and using different liquid metal pairs as working fluids: gallium liquid metal over mercury (immiscible case) or gallium over GaInSn eutectic alloy (miscible case). Despite the small difference in electrical conductivity, the stability theory of [3] suggests that metal pad roll instability occurs for reasonable values of the imposed magnetic field and electrical current. We confirm this theoretical prediction with some very challenging direct numerical simulations of the multiphase magnetohydrodynamical flow in this set-up, done with our massively parallel solver SFEMaNS [4].

Keywords: liquid metal battery; aluminum reduction cell; metal pad roll instability

  • Lecture (Conference) (Online presentation)
    14th World Congress on Computational Mechanics, 11.-15.01.2021, Paris, Frankreich

Permalink: https://www.hzdr.de/publications/Publ-31628
Publ.-Id: 31628


Propagation of spin waves through a Néel domain wall

Wojewoda, O.; Hula, T.; Flajšman, L.; Vaňatka, M.; Gloss, J.; Holobrádek, J.; Staňo, M.; Stienen, S.; Körber, L.; Schultheiß, K.; Schmid, M.; Schultheiß, H.; Urbánek, M.

Spin waves have the potential to be used as a next-generation platform for data transfer and processing as they can reach wavelengths in the nanometer range and frequencies in the terahertz range. To realize a spin-wave device, it is essential to be able to manipulate the amplitude as well as the phase of spin waves. Several theoretical and recent experimental works have also shown that the spin-wave phase can be manipulated by the transmission through a domain wall (DW). Here, we study propagation of spin waves through a DW by means of micro-focused Brillouin light scattering microscopy (μBLS). The 2D spin-wave intensity maps reveal that spin-wave transmission through a Néel DW is influenced by a topologically enforced circular Bloch line in the DW center and that the propagation regime depends on the spin-wave frequency. In the first regime, two spin-wave beams propagating around the circular Bloch line are formed, whereas in the second regime, spin waves propagate in a single central beam through the circular Bloch line. Phase-resolved μBLS measurements reveal a phase shift upon transmission through the domain wall for both regimes. Micromagnetic modeling of the transmitted spin waves unveils a distortion of their phase fronts, which needs to be taken into account when interpreting the measurements and designing potential devices. Moreover, we show that, by means of micromagnetic simulations, an external magnetic field can be used to move the circular Bloch line within the DW and to manipulate spin-wave propagation.
The authors thank R. Schäfer and O. Fruchart for the discussions on the DW classification.
This research was supported by the CEITEC Nano+ project (No. CZ.02.1.01/0.0/0.0/16013/0001728) and Austrian Science Fund (FWF) project I1937. M. Staňo acknowledges support by the ESF under the project CZ.02.2.69/0.0/0.0/19_074/0016239. CzechNanoLab project LM2018110 funded by MEYS CR is gratefully acknowledged for the financial support of the measurement and sample fabrication at the CEITEC Nano Research Infrastructure.

Keywords: Magnetic ordering; Spectrum analyzer; Light scattering; Magnetic force microscopy

Permalink: https://www.hzdr.de/publications/Publ-31627
Publ.-Id: 31627


Zero-field propagation of spin waves in waveguides prepared by focused ion beam direct writing

Flajšman, L.; Wagner, K.; Vaňatka, M.; Gloss, J.; Křižáková, V.; Schmid, M.; Schultheiß, H.; Urbánek, M.

Metastable face-centered-cubic Fe78Ni22 thin films are excellent candidates for focused ion beam direct writing of magnonic structures due to their favorable magnetic properties after ion-beam-induced transformation. The focused ion beam transforms the originally nonmagnetic fcc phase into the ferromagnetic bcc phase with additional control over the direction of uniaxial magnetic in-plane anisotropy and saturation magnetization. Local magnetic anisotropy direction control eliminates the need for external magnetic fields, paving the way towards complex magnonic circuits with waveguides pointing in different directions. In the present study, we show that the magnetocrystalline anisotropy in transformed areas is strong enough to stabilize the magnetization in the direction perpendicular to the long axis of narrow waveguides. Therefore, it is possible to propagate spin waves in these waveguides in the favorable Damon-Eshbach geometry without the presence of any external magnetic field. Phase-resolved microfocused Brillouin light scattering yields the dispersion relation of these waveguides in zero as well as in nonzero external magnetic fields.

Keywords: Ferromagnetism; Magnetic Anisotropy; Magnetic phase transition; Magnetization Dynamics; Spin Dynamics; Spin Waves; Structural Phase transition; Focused ion beam

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Permalink: https://www.hzdr.de/publications/Publ-31626
Publ.-Id: 31626


Performance investigation of bulk photoconductive semiconductor switch based on reversely biased p+in+ structure

Hu, L.; Xu, M.; Li, X.; Wang, Y.; Wang, Y.; Dong, H.; Schneider, H.

We present an investigation of a low-energy-triggered bulk gallium arsenide (GaAs) photoconductive semiconductor switch (PCSS) that is characterized by powerful avalanche domains. The performance of the switch is investigated using a reversely biased p⁺-i-n⁺ structure with 0.625-mm thickness, and the 8.0-kV, 170-ps bulk PCSS that is triggered by a 905-nm laser at the energy of 5.7 nJ is achieved. In the low-energy-triggered mode, it is found experimentally that the reduction of required energy for switching operation is not always kept by the continuous increase of the bias field in the bulk PCSS due to Franz–Keldysh effect. We also analyze the triggering efficiency depending on the laser wavelength numerically, and results indicate that the earlier formation of the powerful avalanche domains is realized by the increased wavelength, which causes lower laser energy for switching operation. Moreover, the prestudy of high-power microwave (HPM) applications is also introduced utilizing bulk PCSS, and we constructed the basic units for ultrawide-band (UWB) pulse and HPM-driven pulse.

Keywords: photoconductive semiconductor switch; avalanche domain; GaAs

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Permalink: https://www.hzdr.de/publications/Publ-31625
Publ.-Id: 31625


Mode-locked short pulses from an 8 μm wavelength semiconductor laser

Hillbrand, J.; Opačcak, N.; Piccardo, M.; Schneider, H.; Strasser, G.; Capasso, F.; Schwarz, B.

Quantum cascade lasers (QCL) have revolutionized the generation of mid-infrared light. Yet, the ultrafast carrier transport in mid-infrared QCLs have so far constituted a seemingly insurmountable obstacle for the formation of ultrashort light pulses. Here, we demonstrate that careful quantum design of the gain medium and control over the intermode beat synchronization enable transform-limited picosecond pulses from QCL frequency combs. Both an interferometric radio-frequency technique and second-order autocorrelation shed light on the pulse dynamics and confirm that mode-locked operation is achieved from threshold to rollover current. Furthermore, we show that both antiphase and in-phase synchronized states exist in QCLs. Being electrically pumped and compact, mode-locked QCLs pave the way towards monolithically integrated non-linear photonics in the molecular fingerprint region beyond 6 μm wavelength.

Keywords: quantum cascade laser; two-photon QWIP; mid-infrared, frequency comb

Permalink: https://www.hzdr.de/publications/Publ-31624
Publ.-Id: 31624


Wire-mesh sensor measurements of single-phase liquid flows at different temperatures

Wiedemann, P.; de Assis Dias, F.; Schleicher, E.; Hampel, U.

The dataset contains raw data belonging to Wiedemann et al.: Temperature Compensation for Conductivity-Based Phase Fraction Measurements with Wire-Mesh Sensors in Gas-Liquid Flows of Dilute Aqueous Solutions, Sensors 2020, 20(24), 7114; https://doi.org/10.3390/s20247114.

A 16x16 conductivity-based wire-mesh sensor was placed in a single-phase liquid loop with adjustable fluid temperature. The dataset includes the wire-mesh sensor measurements with water at several temperature levels from 12.5°C to 80°C and the corresponding electrical conductivites. Two water samples, namely deionized water and a mixed water sample, were investigated. The latter one is composed of 95% deionized water and 5% local tap water.

Keywords: wire-mesh sensor; temperature compensation; electrical conductivity

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Permalink: https://www.hzdr.de/publications/Publ-31623
Publ.-Id: 31623


High-Intensity Laser-Driven Oxygen Source from CW Laser-Heated Titanium Tape Targets

Kondo, K.; Nishiuchi, M.; Sakaki, H.; Dover, N. P.; Lowe, H. F.; Miyahara, T.; Watanabe, Y.; Ziegler, T.; Zeil, K.; Schramm, U.; Ditter, E. J.; Hicks, G. S.; Ettlinger, O. C.; Najmudin, Z.; Kiriyama, H.; Kando, M.; Kondo, K.

The interaction of high-intensity laser pulses with solid targets can be used as a highly charged, energetic heavy ion source. Normally, intrinsic contaminants on the target surface suppress the performance of heavy ion acceleration from a high-intensity laser–target interaction, resulting in preferential proton acceleration. Here, we demonstrate that CW laser heating of 5 µm titanium tape targets can remove contaminant hydrocarbons in order to expose a thin oxide layer on the metal surface, ideal for the generation of energetic oxygen beams. This is demonstrated by irradiating the heated targets with a PW class high-power laser at an intensity of 5 x 10^21 W/cm^2, showing enhanced acceleration of oxygen ions with a non-thermal-like distribution. Our new scheme using a CW laser-heated Ti tape target is promising for use as a moderate repetition energetic oxygen ion source for future applications.

Keywords: Ti Sapphire laser; high-power laser; laser-driven heavy ion acceleration; surface treatment; CW laser heating; oxygen ion source

Permalink: https://www.hzdr.de/publications/Publ-31622
Publ.-Id: 31622


Chemical reactions in bubbly flows

Hampel, U.; Kipping, R.; Zähringer, K.; Kováts, P.; Sommerfeld, M.; Taborda, M. A.; Rzehak, R.; Hlawitschka, M.; Klüfers, P.; Oßberger, M.

Reactive bubbly flows are found in many chemical and biochemical process-es. They are characterized by complex hydrodynamics that govern global mass transfer and reaction rates. Effects, which have to be taken into account when modelling and simulating the reaction progress are enhanced bubble-bubble interaction and bubble-induced turbulence as well as swarm-induced macro-convection. This poses great challenges on both, experimental analysis and numerical simulation. Bubble swarms at higher gas fractions are opaque, which limits the use of optical flow measurement techniques. Moreover, simu-lations at industrial scale are only feasible with point-bubble-based Euler-Euler or Euler-Lagrange approaches. Such approaches require closure relations, which account for all relevant interfacial forces as well as bubble-induced tur-bulence and coalescence including swarm effects. This chapter describes the progress in the experimental analysis and CFD simulation of reactive bubbly flows achieved during the time of the DFG Priority Programme SPP 1740. Ex-perimental studies in bubble columns reported in this Chapter were carried out at TU Dresden and OVGU Magdeburg. CFD model development and simula-tion has been carried out at OVGU Magdeburg using the Euler-Euler and Euler-Lagrange method and at TU Kaiserslautern and Helmholtz-Zentrum Dresden-Rossendorf using the Euler-Euler approach. As reaction systems the chemi-sorption of CO2 in NaOH solution and the reaction of FeII(edta) with NO were studied.

  • Book chapter
    Michael Schlüter, Dieter Bothe, Sonja Herres-Pawlis, Ulrich Nieken: Reactive Bubbly Flows, Heidelberg: Springer, 2021, 978-3-030-72361-3, 583-619
    DOI: 10.1007/978-3-030-72361-3_23

Permalink: https://www.hzdr.de/publications/Publ-31621
Publ.-Id: 31621


Experimental studies on the hydrodynamics, mass transfer and reaction in bubble swarms with ultrafast X-ray tomography and local probes

Kipping, R.; Kryk, H.; Hampel, U.

The main focus of this project was the experimental investigation of hydrody-namics and mass transfer characteristics together with a chemical reaction in a bubble column at higher gas holdup. Experiments were performed for chemical absorption of CO2 in alkaline solution of different pH, at homogenous bubbly flow conditions and up to 17% gas holdup. Ultrafast electron beam X-ray to-mography (UFXCT) has been used to obtain local gas holdup data and bubble characteristics and a wire-mesh sensor was used to measure species concentra-tion fields in the liquid bulk. In addition, experiments with the reactive system FeII(edta)/NO were carried out and a new a fiber optical probe was employed for local measurement of product concentration in the bubble wake.

  • Book chapter
    Michael Schlüter, Dieter Bothe, Sonja Herres-Pawlis, Ulrich Nieken: Reactive Bubbly Flows, Heidelberg: Spinger, 2021, 978-3-030-72361-3, 115-136
    DOI: 10.1007/978-3-030-72361-3_7

Permalink: https://www.hzdr.de/publications/Publ-31620
Publ.-Id: 31620


Frequency control of auto-oscillations of the magnetization in spin Hall nano-oscillators

Hache, T.

This thesis experimentally demonstrates four approaches of frequency control of magnetic autooscillations in spin Hall nano-oscillators (SHNOs).
The frequency can be changed in the GHZ-range by external magnetic fields as shown in this work. This approach uses large electromagnets, which is inconvenient for future applications.The nonlinear coupling between oscillator power and frequency can be used to control the latter one by changing the applied direct current to the SHNO. The frequency can be controlled over a range of several 100 MHz as demonstrated in this thesis.
The first part of the experimental chapter demonstrates the synchronization (injection-locking) between magnetic auto-oscillations and an external microwave excitation. The additionally applied microwave current generates a modulation of the effective magnetic field, which causes the interaction with the auto-oscillation. Both synchronize over a range of several 100 MHz. In this range, the auto-oscillation frequency can be controlled by the external stimulus. An increase of power and a decrease of line width is achieved in the synchronization range. This is explained by the increased coherence of the auto-oscillations. A second approach is the synchronization of auto-oscillations to an alternating magnetic field. This field is generated by a freestanding antenna, which is positioned above the SHNO.
The second part of the experimental chapter introduces a bipolar concept of SHNOs and its experimental demonstration. In contrast to conventional SHNOs, bipolar SHNOs generate autooscillations for both direct current polarities and both directions of the external magnetic field. This is achieved by combining two ferromagnetic layers in an SHNO. The combination of two different ferromagnetic materials is used to switch between two frequency ranges in dependence of the direct current polarity since it defines the layer showing auto-oscillations. This approach can be used to change the frequency in the GHz-range by switching the direct current polarity.

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Permalink: https://www.hzdr.de/publications/Publ-31619
Publ.-Id: 31619


Frequency control of auto-oscillations of the magnetization in spin Hall nano-oscillators

Hache, T.

This thesis experimentally demonstrates four approaches of frequency control of magnetic autooscillations in spin Hall nano-oscillators (SHNOs).
The frequency can be changed in the GHZ-range by external magnetic fields as shown in this work. This approach uses large electromagnets, which is inconvenient for future applications.The nonlinear coupling between oscillator power and frequency can be used to control the latter one by changing the applied direct current to the SHNO. The frequency can be controlled over a range of several 100 MHz as demonstrated in this thesis.
The first part of the experimental chapter demonstrates the synchronization (injection-locking) between magnetic auto-oscillations and an external microwave excitation. The additionally applied microwave current generates a modulation of the effective magnetic field, which causes the interaction with the auto-oscillation. Both synchronize over a range of several 100 MHz. In this range, the auto-oscillation frequency can be controlled by the external stimulus. An increase of power and a decrease of line width is achieved in the synchronization range. This is explained by the increased coherence of the auto-oscillations. A second approach is the synchronization of auto-oscillations to an alternating magnetic field. This field is generated by a freestanding antenna, which is positioned above the SHNO.
The second part of the experimental chapter introduces a bipolar concept of SHNOs and its experimental demonstration. In contrast to conventional SHNOs, bipolar SHNOs generate autooscillations for both direct current polarities and both directions of the external magnetic field. This is achieved by combining two ferromagnetic layers in an SHNO. The combination of two different ferromagnetic materials is used to switch between two frequency ranges in dependence of the direct current polarity since it defines the layer showing auto-oscillations. This approach can be used to change the frequency in the GHz-range by switching the direct current polarity.

Keywords: spin Hall nano-oscillator; magnetic auto-oscillations; pure spin current; bipolar; injection-locking; microwave; spin-wave; spin orbit torque; spin-transfer torque; magnetization dynamic

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  • Doctoral thesis
    TU Chemnitz, 2021

Permalink: https://www.hzdr.de/publications/Publ-31617
Publ.-Id: 31617


Magnetic texture based magnonics

Yu, H.; Xiao, J.; Schultheiß, H.

The spontaneous magnetic orders arising in ferro-, ferri- and antiferromagnets stem from various magnetic interactions. Depending on the interplay and competition among the Heisenberg exchange interaction, Dzyaloshinskii-Moriya exchange interaction, magnetic dipolar interaction and crystal anisotropies, a great variety of magnetic textures may be stabilized, such as magnetic domain walls, vortices, Skyrmions and spiral helical structures. While each of these spin textures responds to external forces in a specific manner with characteristic resonance frequencies, they also interact with magnons, the fundamental collective excitation of the magnetic order, which can propagate in magnetic materials free of charge transport and therefore with low energy dissipation. Recent theories and experiments found that the interplay between spin waves and magnetic textures is particularly interesting and rich in physics. In this review, we introduce and discuss the theoretical framework of magnons living on a magnetic texture background, as well as recent experimental progress in the manipulation of magnons via magnetic textures. The flexibility and reconfigurability of magnetic textures are discussed regarding the potential for applications in information processing schemes based on magnons.

Keywords: magnetic textures; spin waves; magnetization dynamics; Skyrmions; antiferromagnets; Dzyaloshinskii Moria; chiral magnetism; domain walls; vortices

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Permalink: https://www.hzdr.de/publications/Publ-31616
Publ.-Id: 31616


Potential microbial influence on the performance of subsurface, salt-based nuclear waste repositories

Swanson, J. S.; Bader, M.; Cherkouk, A.

Microrganisms can influence the performance of nuclear waste repositories through activities or processes that affect radionuclide migration. In the case of subterranean salt-based repositories, the influence of microorganisms may be limited by the unique constraints of such sutes (e.g. high ionic strength, low water activity, nutient supply) coupled with conditions of the repositories themselves (e.g. anoxia,radioactivity, high temperatures). Indigenous extremely halophilic archaea can survive long-term at high ionic strength and may remain viable throughout a repository´s lifetime. However, their ability to affect repository performance through waste and radionuclide transformation is uncertain, as they are mostly arobic and repositories are projected to be anoxic. Microorganisms introduced with waste may contribute to transformations within drums but may not survive high salt concentrations once drums have been breached and inundated with brine. However, both indigenous and introduced organisms may associate with radionuclides and enhance or mitigate radionuclide migration in this capacity.

  • Book chapter
    Jonathan Lloyd, Andrea Cherkouk: The Microbiology of Nuclear Waste Disposal 1st Edition, Amsterdam: Elsevier, 2020, 978-0-12-818695-4

Permalink: https://www.hzdr.de/publications/Publ-31615
Publ.-Id: 31615


Molecular techniques for understanding microbial abundance and activity in clay barriers used for geodisposal

Mijnendonckx, K.; Monsieurs, P.; Cerna, K.; Hlavackova, V.; Steinova, J.; Burzan, N.; Bernier-Latmani, R.; Boothman, C.; Miettinen, H.; Kluge, S.; Matschiavelli, N.; Cherkouk, A.; Jroundi, F.; Larbi Merroun, M.; Engel, K.; Neufeld, J. D.; Leys, N.

Clays are commonly used in design concepts for geological disposal of nuclear waste. It is thus essential to identify and quantify microbial communities in clay-rich samples to study microbial processes during geological disposal. Although advances in culture-independent techiques have enablesd detailed studies of microbial communities in diverse ecosystems, the efficiency and sensitivity of these molecular techniques depend on chartacteristics of the environment studied. Moreover, the outcome of nucleic acid-based approaches depends on the extraction method, prmer specificity, PCR amplification, sequencing artefacts and downstream bioinformatic analyses. Clays are recalcitrant to DNA extraction and are challenging for analysis by standard techniques using viability stains and measurement of metabolic activity. This chapter explores the impact of various sequencing and bioinformatic pipelines used for 16S rRNA gene profiling of microbial communities and compares the efficiency of different DNA extraction methods from clay. Moreover, non-DNA based techniques used to assess microbial activity and viability in clay samples will be also discussed.

  • Book chapter
    Jonathan Lloyd Andrea Cherkouk: The Microbiology of Nuclear Waste Disposal 1st Edition, Amsterdam: Elsevier, 2020, 978-0-12-818695-4

Permalink: https://www.hzdr.de/publications/Publ-31614
Publ.-Id: 31614


The Microbiology of Nuclear Waste Disposal

Lloyd, J.; Cherkouk, A.

The Microbiology of Nuclear Waste Disposal is a state-of-the-art reference featuring contributions focusing on the impact of microbes on the safe long-term disposal of nuclear waste. This book is the first to cover this important emerging topic, and is written for a wide audience encompassing regulators, implementers, academics, and other stakeholders. The book is also of interest to those working on the wider exploitation of the subsurface, such as bioremediation, carbon capture and storage, geothermal energy, and water quality.

Planning for suitable facilities in the U.S., Europe, and Asia has been based mainly on knowledge from the geological and physical sciences. However, recent studies have shown that microbial life can proliferate in the inhospitable environments associated with radioactive waste disposal, and can control the long-term fate of nuclear materials. This can have beneficial and damaging impacts, which need to be quantified.

  • Book (Editorship)
    Amsterdam: Elsevier, 2020
    ISBN: 9780128186954

Permalink: https://www.hzdr.de/publications/Publ-31613
Publ.-Id: 31613


Raw data: CoFeB beamtime overview

Awari, N.; Deinert, J.-C.

Collection of raw data and evaluated data for the CoFeB experiments carried out in collaboration with Stefano Bonetti et al.

Keywords: Spin dynamics; nutation; CoFeB; Terahertz

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Permalink: https://www.hzdr.de/publications/Publ-31612
Publ.-Id: 31612


Parametric optimization in rougher flotation performance of a sulfidized mixed copper ore

Hassanzadehmahaleh, A.; Azizi, A. A.; Masdarian, M. A.; Bahri, Z. C.; Niedoba, T. D.; Surowiak, A. D.

The dominant challenge of current copper beneficiation plants is the low recoverability of oxide copper-bearing minerals associated with sulfide type ones. Furthermore, applying commonly used conventional methodologies does not allow the interactional effects of critical parameters in the flotation processes to be investigated, which is mostly overlooked in the literature. To tackle this issue, the present paper aimed at characterizing the behavior of five key effective factors and their interactions in a sulfidized copper ore. In this context, dosage of collector (sodium di-ethydithiophosphate, 60–100 g/t), depressant (sodium silicate, 80–120 g/t) and frother (methyl isobutyl carbinol (MIBC), 6–10 g/t), pulp pH (7–11) and agitation rate (900–1300 rpm) were examined and statistically analyzed using response surface methodology. Flotation experiments were conducted in a Denver type agitated flotation cell at the rougher stage. The experimental results showed that increasing the pH (from 8 to 10) at low agitation rate (1000 rpm) enhanced the recovery from 80.36% to 85.22%, while at high agitation rate (1200 rpm), a slight declination occurred in the recovery. Meanwhile, increasing the collector dosage at a lower frother value (7 g/t), caused a reduction of about 4.44% in copper recovery owing to the interactions between factors, whereas at a higher frother level (9 g/t), the recovery was almost unchanged. The optimization process was also performed using the goal function approach, and maximum copper recovery of 92.75% was obtained using ~70 g/t collector, 110 g/t depressant, 7 g/t frother, pulp pH of 10 and 1000 rpm agitation rate.

Keywords: sulfidized copper ore; flotation; interaction effects; recovery; optimization

Permalink: https://www.hzdr.de/publications/Publ-31611
Publ.-Id: 31611


Sachbericht DELTA

Fogel, S.; Putra, R. A.

Das Ziel des Teilvorhabens des HZDR war die thermodynamische, strömungstechnische und regelungstechnische Beschreibung und Auslegung des Gesamtsystems des DELTA-Reaktors. Mit Hilfe von geeigneten Simulationsmethoden sollte das Betriebsverhalten des räumlich und thermisch eng gekoppelten Reaktorkonzepts von Hochtemperaturelektrolyse sowie Methanolsynthese untersucht und die durch den Projektpartner TUD-WKET durchgeführten Arbeiten zur konstruktiven Gestaltung des Prozesses begleitet und unterstützt werden. Im Projektverlauf sollte außerdem gemeinsam mit dem Projektpartner TUD-WKET ein Mess- und regelungstechnisches Konzept entwickelt sowie ein geeignetes Analysengerät zur Bestimmung des Produktgasgemisches des Reaktionssystems ausgewählt, beschafft und in die experimentelle Versuchsplattform integriert werden. Darüber hinaus sollte im Rahmen des Teilprojektes ein Simulationsmodell auf Systemebene erstellt und das Verhalten des DELTA-Reaktors unter fluktuierenden Lasten beschrieben werden.

Keywords: Power-to-X; Methanol; SOEC; Renewable Energies; Modelling; CFD; FEM

  • Other report
    Dresden: HZDR, 2020
    133 Seiten

Permalink: https://www.hzdr.de/publications/Publ-31610
Publ.-Id: 31610


Point and extended defects in heteroepitaxial β-Ga2O3 films

Saadatkia, P.; Agarwal, S.; Hernandez, A.; Reed, E.; Brackenbury, I. D.; Codding, C. L.; Liedke, M. O.; Butterling, M.; Wagner, A.; Selim, F. A.

Ga2O3 is emerging as an excellent potential semiconductor for high power and optoelectronic devices.
However, the successful development of Ga2O3 in a wide range of applications requires a full understanding of the role and nature of its point and extended defects. In this work, high quality epitaxial Ga2O3 films were grown on sapphire substrates by metal-organic chemical vapor deposition and fully characterized in terms of structural, optical, and electrical properties. Then defects in the films were investigated by a combination of depth-resolved Doppler broadening and lifetime of positron annihilation spectroscopies and thermally stimulated emission (TSE). Positron annihilation techniques can provide information about the nature and concentration of defects in the films, while TSE reveals the energy level of defects in the bandgap. Despite very good structural properties, the films exhibit short positron diffusion length, which is an indication of high defect density and long positron lifetime, a sign for the formation of Ga vacancy related defects and large vacancy clusters. These defects act as deep and shallow traps for charge carriers as revealed from TSE, which explains the reason behind the difficulty of developing conductive Ga2O3 films on non-native substrates. Positron lifetime measurements also show nonuniform distribution of vacancy clusters throughout the film depth. Further, the work investigates the modification of defect nature and properties through thermal treatment in various environments. It demonstrates the sensitivity of Ga2O3 microstructures to the growth and thermal treatment environments and the significant effect of modifying defect structure on the bandgap and optical and electrical properties of Ga2O3

Keywords: positron annihilation spectroscopy; positron annihilation lifetime spectroscopy; Doppler broadening; defetcs; Ga2O3

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Permalink: https://www.hzdr.de/publications/Publ-31609
Publ.-Id: 31609


Contribution of bentonite and cementitious material to actinide retention under hyperalkaline conditions and increased ionic strength

Schmeide, K.

Our research aligns to conditions reported by the 'AnSichT' project, which evaluated the feasibility of a repository in German clay formations [1]. According to the developed site model 'NORD', Ca-bentonite and concrete will be used in the geo-engineered barrier as buffer and borehole sealing material as well as for stabilization of disposal tunnels. Pore waters of the North German clay deposits are characterized by high ionic strengths up to 4 M [2, 3]. The contact of such saline formation waters with concrete can result in an enhanced corrosion of concrete which will lead to formation of secondary phases and to the evolution of highly alkaline cement pore waters (10 < pH < 13). The hyperalkaline solutions, in turn, can influence the retention potential of the bentonite buffer as well as of the surrounding clay host rock towards radionuclides.
The U(VI) retention on Ca-bentonite at hyperalkaline conditions in mixed electrolyte solutions (‘diluted Gipshut solution’, I = 2.6 M) was found to be very effective at pH>10, even in the presence of carbonate and despite the prevalence of anionic aqueous uranyl species [4]. Above a certain pH, depending on the concentration of carbonate in solution, carbonate does not play a role in the aqueous U(VI) speciation anymore due to the predominance of hydrolysis. Two U(VI) surface complexes were identified by site-selective TRLFS and XAS.
The stability of U(VI) and Cm(III) doped calcium (aluminate) silicate hydrate (C-(A-)S-H) phases, as main phases of hardened cement paste, at high ionic strengths conditions was studied applying leaching solutions which simulate the contact with North German claystone formation water [5, 6]. With regard to C-S-H stability and radionuclide release, differences were found in dependence on C/S ratio, composition of leaching solution and kind of radionuclide. The high retention capability of C-S-H gel towards U(VI) and Cm(III) remained constant in NaCl- and Na2SO4-containing solutions with increased ionic strength. In the presence of carbonate, however, U(VI) retention was coupled to the alteration stage of the C-S-H structure as well as to pH evolution of leaching solution. The Cm(III) mobilization from C-S-H gel was very low due to additional Cm(III) incorporation into secondary phases as shown by site-selective TRLFS and XRD.
The results show that both bentonite and cementitious material constitute an important retention barrier for radionuclides under hyperalkaline conditions and increased ionic strength.

Keywords: bentonite; cement; concrete; uranium; organics; ionic strength

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  • Lecture (Conference)
    DAEF 2022 – 3rd Conference on Key Topics in Deep Geological Disposal, 04.-06.07.2022, Köln, Germany

Permalink: https://www.hzdr.de/publications/Publ-31608
Publ.-Id: 31608


Non-plasmonic improvement in photoconductive THz emitters using nano- and micro-structured electrodes

Singh, A.; Welsch, M.; Winnerl, S.; Helm, M.; Schneider, H.

We investigate here terahertz enhancement effects arising from micrometer and nanometer structured electrode features of photoconductive terahertz emitters. Nanostructured electrode based emitters utilizing the palsmonic effect are currently one of the hottest topics in the research field. We demonstrate here that even in the absence of any plasmonic resonance with the pump pulse, such structures can improve the antenna effect by enhancing the local d.c. electric field near the structure edges. Utilizing this effect in Hilbert-fractal and grating-like designs, enhancement of the THz field of up to a factor of ~ 2 is observed. We conclude that the cause of this THz emission enhancement in our emitters is different from the earlier reported plasmonic-electrode effect in a similar grating-like structure. In our structure, the proximity of photoexcited carriers to the electrodes and local bias field enhancement close to the metallization cause the enhanced efficiency. Due to the nature of this effect, the THz emission efficiency is almost independent of the pump laser polarization. Compared to the plasmonic effect, these effects work under relaxed device fabrication and operating conditions.

Keywords: Terahertz sources; Teraherhertz emitter; Photoconductive THz emitter; Photoconductive antenna

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Permalink: https://www.hzdr.de/publications/Publ-31607
Publ.-Id: 31607


Successful user operation of a superconducting radio-frequency photo electron gun with Mg cathodes at ELBE

Teichert, J.; Arnold, A.; Ciovati, G.; Deinert, J.-C.; Evtushenko, P.; Justus, M.; Kneisel, P.; Kovalev, S.; Kuntzsch, M.; Lehnert, U.; Lu, P.; Ma, S.; Murcek, P.; Michel, P.; Ryzhov, A.; Schaber, J.; Schneider, C.; Schurig, R.; Steinbrück, R.; Vennekate, H.; Will, I.; Xiang, R.

At the ELBE high power radiation facility, the second version of a superconducting radio frequency (SRF) photoinjector has been put into operation and is now routinely applied for user operation at the ELBE electron accelerator. SRF guns are suitable for generating continuous wave (CW) electron beam with high average currents and high beam brightness. The SRF gun at ELBE has the goal to generate short electron pulses with bunch charges of 200-300 pC at typical repetition rates of 100 kHz for the production of super radiant, coherent terahertz radiation. The SRF gun includes a 3.5-cell, 1.3 GHz niobium cavity and a superconducting solenoid. A support system with liquid nitrogen (LN2) cooling allows the operation of normal-conducting, high quantum efficiency photo cathodes. In the paper we present the design and performance of the SRF gun as well as beam measurements for the operation with Mg photocathodes and an acceleration gradient of 8 MV/m (4 MeV kinetic energy). Finally, we discuss the SRF gun application for production of coherent terahertz radiation at the ELBE facility.

Keywords: electron source; THz radiation; electron accelerator; photo injector; superconducting radio-frequency; photo cathode

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Permalink: https://www.hzdr.de/publications/Publ-31606
Publ.-Id: 31606


Temperature Compensation for Conductivity-Based Phase Fraction Measurements with Wire-Mesh Sensors in Gas-Liquid Flows of Dilute Aqueous Solutions

Wiedemann, P.; de Assis Dias, F.; Schleicher, E.; Hampel, U.

Wire-mesh sensors are well-established scientific instruments for measuring the spatio-temporal phase distribution of two-phase flows based on different electrical conductivities of the phases. Presently, these instruments are also applied in industrial processes and need to cope with dynamic operating conditions increasingly. However, since the quantification of phase fractions is achieved by normalizing signals with respect to a separately recorded reference measurement, the results are sensitive to temperature differences in any application. Therefore, the present study aims at proposing a method to compensate temperature effects in the data processing procedure. Firstly, a general approach is theoretically derived from the underlying measurement principle and compensation procedures for the electrical conductivity from literature models. Additionally, a novel semi-empirical model is developed on the basis of electrochemical fundamentals. Experimental investigations are performed using a single-phase water loop with adjustable fluid temperature in order to verify the theoretical approach for wire-mesh sensor applications and to compare the different compensation models by means of real data. Finally, the preferred model is used to demonstrate the effect of temperature compensation with selected sets of experimental two-phase data from a previous study. The results are discussed in detail and show that temperature effects need to be handled carefully --- not merely in industrial applications, but particularly in laboratory experiments.

Keywords: wire-mesh sensor; temperature compensation; multicomponent electrolyte solution; ionic conductivity; two-phase thermohydraulics

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Permalink: https://www.hzdr.de/publications/Publ-31605
Publ.-Id: 31605


Gallium-binding peptides as a tool for the sustainable treatment of industrial waste streams

Schönberger, N.; Taylor, C. J.; Schrader, M.; Drobot, B.; Matys, S.; Lederer, F.; Pollmann, K.

Metalliferous process wastewater not only represents a major ecotoxicological burden but can also serve as a secondary raw material source for the recovery of critical raw materials (CRM) like gallium. Smart, innovative strategies are needed for the economic recovery of industrial metals from such CRM sources. Biotechnological approaches are powerful tools to develop effective, selective and eco-friendly strategies in resource recovery. A particularly promising approach utilizes tailor-made biomolecules (such as peptides), that can be engineered to aid in the targeted extraction of individual metals. The application of phage Surface Display technology allows the directed molecular evolution of peptide ligands. This method has been used to identify the Ga-binding peptides TMHHAAIAHPPH, NYLPHQSSSPSR, SQALSTSRQDLR, HTQHIQSDDHLA and NDLQRHRLTAGP. In this study, the metal-binding properties of these peptides were further characterized. The peptides differed decisively in their interaction with gallium; in some cases, complex formation with gallium was strongly dependent on the surrounding buffer conditions. The peptide with the amino acid sequence NYLPHQSSSPSR showed the most promising gallium-binding properties. The site-selective and covalent immobilization of the gallium-binding peptide on polystyrene beads resulted in a robust and efficient material. It is suitable for the selective adsorption and desorption of gallium from industrial wastewater utilizing citric acid as environmentally friendly eluent. Biosorption studies performed with model and real water samples showed an up to ten-fold better adsorption of gallium as well as its effective separation from other contaminants like arsenic. Computer modeling suggests the probable structure of the peptide in aqueous solution and postulate a possible binding site for gallium.

Keywords: Industrial wastewater; Peptide-based material; Biosorption; Gallium; Arsenic; Computer modeling; Isothermale titration microcalorimetry

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Permalink: https://www.hzdr.de/publications/Publ-31604
Publ.-Id: 31604


Accelerating Finite-temperature Kohn-Sham Density Functional Theory with Deep Neural Networks

Ellis, J. A.; Fiedler, L.; Popoola, G. A.; Modine, N. A.; Stephens, J. A.; Thompson, A. P.; Cangi, A.; Rajamanickam, S.

We present a numerical modeling workflow based on machine learning which reproduces the total energies produced by Kohn-Sham density functional theory (DFT) at finite electronic temperature to within chemical accuracy at negligible computational cost. Based on deep neural networks, our workflow yields the local density of states (LDOS) for a given atomic configuration. From the LDOS, spatially resolved, energy-resolved, and integrated quantities can be calculated, including the DFT total free energy, which serves as the Born-Oppenheimer potential energy surface for the atoms. We demonstrate the efficacy of this approach for both solid and liquid metals and compare results between independent and unified machine-learning models for solid and liquid aluminum. Our machine-learning density functional theory framework opens up the path towards multiscale materials modeling for matter under ambient and extreme conditions at a computational scale and cost that is unattainable with current algorithms.

Keywords: machine learning; density functional theory; materials science

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  • Open Access Logo Physical Review B 104(2021), 035120
    DOI: 10.1103/PhysRevB.104.035120
    Cited 32 times in Scopus
  • Open Access Logo Poster (Online presentation)
    41st Workshop on High-Energy-Density Physics with laser and ion beams, 01.-05.02.2021, Online, Germany
  • Lecture (Conference) (Online presentation)
    APS March Meeting 2021, 15.-19.03.2021, Online, USA

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Permalink: https://www.hzdr.de/publications/Publ-31603
Publ.-Id: 31603


Code, data and supplementary material for: An improved contact method for quantifying the mixing of a binary granular mixture

Papapetrou, T. N.; Lecrivain, G.; Bieberle, M.; Boudouvis, A.; Hampel, U.

This material is related to the publication "An improved contact method for quantifying the mixing of a binary granular mixture", submitted on 13.05.2020 to Granular Matter. The original camera video, an intermediate masked video and the final preprocessed video used in the calculations, made from frames 4-1004 of the masked one, are included. The code used for all calculations in the paper and supplementary material, including the implementation of the mixing index evaluation methods, as well as the static artificial images and the generated data, are also included. All images used in the calculations are stored in the required data form. The figures of the paper are also included, as well as two supplementary materials: a version of Figure 12 with the points of the original contact method, and a discussion on the calculation of the minimum modified contact length.

Keywords: binary particle mixing; rotating drum; image analysis; mixing index; contact method; variance method

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Permalink: https://www.hzdr.de/publications/Publ-31602
Publ.-Id: 31602


Insight into the structure-property relationship of UO2 nanoparticles

Gerber, E.; Romanchuk, A. Y.; Weiss, S.; Bauters, S.; Schacherl, B.; Vitova, T.; Hübner, R.; Shams Aldin Azzam, S.; Detollenaere, D.; Banerjee, D.; Butorin, S. M.; Kalmykov, S. N.; Kvashnina, K.

Fast chemical deposition of uranium(IV) under reducing conditions at pH 8-11 results in the formation of highly crystalline UO2 nanoparticles (NPs) with sizes of 2-3 nm, which is similar to the formation mechanism of PuO2 NPs. UO2 NPs are characterized by various microscopic and spectroscopic techniques including high energy transmission electron microscopy (HRTEM), high energy resolution fluorescence detection (HERFD) X-ray absorption spectroscopy and extended X-ray absorption fine structure (EXAFS) spectroscopy. Despite U(IV) being the dominant oxidation state of the freshly prepared UO2 NPs, they readily oxidize to U4O9 with time and under the X-ray beam. This oxidation of NPs is accompanied by their growth in size to 6 nm. The high tendency of UO2 NPs towards oxidation differs from PuO2 NPs’ behaviour due to the extremely high stability of Pu(IV) and much lower stability of oxidized Pu(V/VI) as compared to U(V/VI).

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Permalink: https://www.hzdr.de/publications/Publ-31601
Publ.-Id: 31601


The effect of Pd(II) chloride complexes anchoring on the formation and properties of Pd/MgAlOx catalysts

Belskaya, O. B.; Zaikovskii, V. I.; Gulyaeva, T. I.; Talsi, V. P.; Trubina, S. V.; Kvashnina, K.; Nizovskii, A. I.; Kalinkin, A. V.; Bukhtiyarov, V. I.; A. Likholobov, V.

Pd(II) chloride complexes were anchored using magnesium-aluminum layered double
hydroxides (LDHs) with interlayer anions 3 2 and ), which possess different exchange properties, and MgAl mixed oxide during its rehydration. It was shown that the catalysts of the same chemical composition with different size, morphology and electronic state of supported palladium particles can be synthesized by varying the localization of Pd precursor. The properties of Pd/MgAlOx catalysts were studied in aqueous-phase hydrogenation of furfural.
Anchoring of the Pd precursor in the interlayer space of LDHs is accompanied by the formation of non-isometric agglomerated palladium particles which contain less oxidized metal and show a higher activity toward hydrogenation of furfural. Magnesium-aluminum oxides in Pd/MgAlOx catalysts are rehydrated in the aqueous-phase reaction to yield the activated MgAl-LDH species as a support, which promotes the furfural conversion via hydrogenation of the furan cycle.

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Permalink: https://www.hzdr.de/publications/Publ-31600
Publ.-Id: 31600


Multi- and Hyperspectral Imaging

Lorenz, S.; Jackisch, R.; Booysen, R.; Zimmermann, R.; Gloaguen, R.

Multi- and hyperspectral (MS and HS) imaging are currently deployed at a wide range of spatial dimensions (“scales”), ranging from satellites observing the Earth and other planets down to lab-scale sensing for small sample spectral analysis. New techniques such as UAS-borne imaging or terrestrial scanning of vertical targets are emerging and allow to observe any target at a wide and contiguous range of scales. Deploying spectral imaging on unmanned aerial platforms or drones creates one of the most promising application fields of spectral imaging in the last decade. Lightweight, low-cost, customizable and usable by anyone and nearly anywhere, UAS close the scale gap between airborne and ground-based spectroscopy and offer individual solutions for the respective application. The following chapter will give an insight on the principles of multi- and hyperspectral imaging that are required to understand the physical nature of spectroscopic processes as well as sensor-specific and external influence factors during the acquisition of spectral data. In later sections, the state of the art on drone-borne multi-and hyperspectral sensors, common and application-specific data correction and processing workflows are given to outline remaining challenges.

  • Open Access Logo Book chapter
    A. Eltner, D. Hoffmeister, A. Kaiser, P. Karrasch, L. Klingbeil, A. Rovere, C. Stöcker: UAV in Environmental Sciences, Darmstadt: Wissenschaftliche Buchgesellschaft (WBG), 2022, 978-3-534-40588-6

Permalink: https://www.hzdr.de/publications/Publ-31599
Publ.-Id: 31599


Development of New 14 Cr ODS Steels by Using New Oxides Formers and B as an Inhibitor of the Grain Growth

Meza, A.; Macía, E.; García-Junceda, A.; Antonio Díaz, L.; Chekhonin, P.; Altstadt, E.; Serrano, M.; Eugenia Rabanal, M.; Campos, M.

In this work, new oxide dispersion strengthened (ODS) ferritic steels have been produced by powder metallurgy using an alternative processing route and characterized afterwards by comparing them with a base ODS steel with Y2O3 and Ti additions. Different alloying elements like boron (B), which is known as an inhibitor of grain growth obtained by pinning grain boundaries, and complex oxide compounds (Y-Ti-Zr-O) have been introduced to the 14Cr prealloyed powder by using mechanical alloying (MA) and were further consolidated by spark employing plasma sintering (SPS). Techniques such as x-ray diffraction (XRD), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) were used to study the obtained microstructures.
Micro-tensile tests and microhardness measurements were carried out at room temperature to analyze the mechanical properties of the differently developed microstructures, which was considered to result in a better strength in the ODS steels containing the complex oxide Y-Ti-Zr-O. In addition, small punch (SP) tests were performed to evaluate the response of the material under high temperatures conditions, under which promising mechanical properties were attained by the materials containing Y-Ti-Zr-O (14Al-X-ODS and 14Al-X-ODS-B) in comparison with the other commercial steel, GETMAT. The differences in mechanical strength can be attributed to the precipitate’s density, nature, size, and to the density of dislocations in each ODS steel.

Permalink: https://www.hzdr.de/publications/Publ-31597
Publ.-Id: 31597


Feature extraction for hyperspectral mineral domain mapping: A test of conventional and innovative methods

Lorenz, S.; Ghamisi, P.; Kirsch, M.; Jackisch, R.; Rasti, B.; Gloaguen, R.

Hyperspectral (HS) imaging holds great potential for the mapping of geological targets. Innovative acquisition modes such as drone-borne or terrestrial remote sensing open up new scales and angles of observation, which allow to analyze small-scale, vertical, or difficult-to-access outcrops. A variety of available sensors operating in different spectral ranges can provide information about the abundance and spatial location of various geologic materials. However geological outcrops are inherently uneven and spectrally heterogeneous, may be covered by dust, lichen or weathering crusts, or contain spectrally indistinct objects, which is why classifications or domain mapping approaches are often used in geoscientific and mineral exploration applications as a means to discriminate mineral associations (e.g. ore or alteration zones) based on overall variations in HS data. Feature extraction (FE) algorithms are prominently used as a preparatory step to identify the first order variations within the data and, simultaneously, reduce noise and data dimensionality. The most established FE algorithms in geosciences are, by far, Principal Component Analysis (PCA) and Minimum Noise Fraction (MNF). Major progress has been conducted in the image processing community within the last decades, yielding innovative FE methods that incorporate spatial information for smoother and more accurate classification results. In this paper, we test the applicability of conventional (PCA, MNF) and innovative FE techniques (OTVCA: Orthogonal total variation component analysis and WSRRR: Wavelet-based sparse reduced-rank regression) on three case studies from geological HS mapping campaigns, including drone-borne mineral exploration, terrestrial paleoseismic outcrop scanning and thermal HS lithological mapping. This allows us to explore the performance of different FE approaches on complex geological data with sparse or partly inaccurate validation data. For all case studies, we demonstrate advantages of innovative FE algorithms in terms of classification accuracy and geological interpretability. We promote the use of advanced image processing methods for applications in geoscience and mineral exploration as a tool to support geological mapping activities.

Keywords: feature extraction; domain mapping; mineral exploration; image processing; hyperspectral imaging; classification

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Permalink: https://www.hzdr.de/publications/Publ-31596
Publ.-Id: 31596


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

Unger, S.; Müller, J.; Bangalore Mohankumar, M.; Rath, S.; Hampel, U.

The annual waste heat available from industry in the European Union is more than 2,700 PJ. Consequently, the utilization of the unexploited thermal energy will decisively contribute to a reduced overall power consumption and lower greenhouse gas emissions. Supercritical carbon dioxide (sCO2) power cycles offer a variety of advantages for that purpose compared to established power cycles. Such are a high conversion efficiency and a turbomachinery with high power density. The pre-cooler is one of the essential components in a sCO2 power cycle and the prediction of the flow and heat transfer characteristics is a challenging task. In the present investigation, cycle layouts were developed for two waste heat sources: a cement plant and a gas compressor station. The pre-cooler design as well as the boundary conditions of the numerical simulation were assessed by an analytical model. The most promising design was the printed circuit heat exchanger with inlet temperatures of 209 °C and 352 °C for the cement kiln and the gas turbine respectively. Subsequently, these heat exchangers were examined in more detail by the numerical code ANSYS CFX for sCO2 mass fluxes between 100 kg/(m^2 s) and 900 kg/(m^2 s). The pressure drop along the sCO2 channel was found insensitive to the channel diameter, but increased with the channel length and mass flux. However, the pressure drop of the coolant stream significantly depends on the channel diameter and thus a larger coolant channel diameter is recommended to maintain a reasonably low pressure drop. The overall heat transfer coefficient is limited by the heat transfer on the coolant side. Ultimately, pre-cooler designs were proposed for both waste heat systems, consisting of compact modular stainless steel plates with an sCO2 channel diameter of 0.5 mm, a coolant channel diameter of 0.8 mm, an sCO2 mass flux of 700 kg/(m^2 s) and a coolant mass flux of 1029 kg/(m^2 s). Based on these results more complex channels having internal fins were studied. The connection angle and the fin height was optimized, in order to improve the heat transfer performance.

Keywords: pre-cooler; numerical simulation; heat transfer; flow characteristics; waste heat

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  • Contribution to proceedings
    The 4th European sCO2 Conference for Energy Systems, 22.-26.03.2021, Prague, Tschechien
    Proceedings of the 4th European sCO2 Conference for Energy Systems
  • Open Access Logo Energies 14(24)(2021), 8278
    DOI: 10.3390/en14248278
    Cited 1 times in Scopus

Permalink: https://www.hzdr.de/publications/Publ-31595
Publ.-Id: 31595


Numerical Analysis Related to the ROCOM Pressurized Thermal Shock Benchmark

Höhne, T.; Kliem, S.

The development, verification and validation of Computational Fluid Dynamics (CFD) codes in reference to nuclear power plant (NPP) safety has been a focus of many research organizations over the last decades. Therefore, a collection of Rossendorf Coolant Mixing Test Facility (ROCOM) CFD-grade experiments were made obtainable to line up a global International Atomic Energy Agency (IAEA) benchmark regarding Pressurized Thermal Shock (PTS) situations. The benchmark experiment describes the complicated flow structures in mixed convection zones of the RPV during PTS events. The experiments were utilized to validate CFD codes. Additionally a test suit with no buoyancy forces was elite to point out the influence of density variations. Compared to the sooner studies, the turbulence models of the CFD code improved a lot. The turbulence modelling approaches show a respectable agreement with the experimental data.

Keywords: Computational Fluid Dynamics; Reactor Design; CFD benchmark; ROCOM; Mixing

Permalink: https://www.hzdr.de/publications/Publ-31594
Publ.-Id: 31594


Computing single-particle flotation kinetics using automated mineralogy data and machine learning

Pereira, L.; Frenzel, M.; Hoang, D. H.; Tolosana Delgado, R.; Rudolph, M.; Gutzmer, J.

Studies of flotation kinetics are essential for understanding, predicting, and optimizing the selective recovery of minerals and metals through flotation. Recently, much effort has been made to use intrinsic ore properties to model flotation behavior. Particle-based characterization methods, e.g. SEM-based image analysis, has enabled much of this development. However, currently available methods for studies of flotation kinetics can not accommodate single-particle data, resulting in incomplete use of data that is readily available today. In this contribution, a method is introduced to fit kinetic flotation models to individual particles. This method, based on lasso-regularized multinomial logistic regression, allows for an in-depth understanding of particle flotation behavior as a function of all measured particle characteristics. With the proposed method, the joint influences of particle size, shape, as well as modal and surface compositions on the recovery of individual particles can be taken into unprecedented consideration. The results of the simulated particle behavior showed a very good agreement to the outcome of experimental works and follow well-described froth-flotation recovery behavior.

Keywords: Geometallurgy; process mineralogy; machine learning; froth flotation; particle-tracking

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Permalink: https://www.hzdr.de/publications/Publ-31593
Publ.-Id: 31593


Automated mineralogy particle dataset: apatite flotation

Hoang, D. H.; Pereira, L.; Kupka, N.; Tolosana Delgado, R.; Frenzel, M.; Rudolph, M.; Gutzmer, J.

This particle dataset was used for demonstrating the particle-tracking method presented in the paper "Computing single-particle flotation kinetics using automated mineralogy data and machine learning", submitted to Minerals Engineering in 08/10/2020, by Lucas Pereira, Max Frenzel, Duong Huu Hoang, Raimon Tolosana-Delgado, Martin Rudolph, Jens Gutzmer from the Helmholtz Institute Freiberg for Resource Technology.

This data belongs to the flotation tests performed by Duong Huu Hoang, and presented in:

Hoang, D.H., Kupka, N., Peuker, U.A., Rudolph, M., 2018. Flotation study of fine grained carbonaceous sedimentary apatite ore – Challenges in process mineralogy and impact of hydrodynamics. Miner. Eng. 121, 196–204. https://doi.org/10.1016/j.mineng.2018.03.021

For this study, phosphate rock samples from the Lao Cai province, Vietnam, were provided by the Vietnam Apatite Limited Company. The objective of the flotation experiments was to determine the best way to efficiently separate fluorapatite from dolomite, calcite and silicates. After grinding for 8 minutes in a laboratory ball mill to assure a d90 of 67 µm, batch flotation tests were performed in a flotation cell built at the TU Bergakademie Freiberg. Corn starch ((C6H10O5)n) gelatinized with sodium hydroxide (NaOH) was used in combination with sodium silicate (Na2SiO3) to depress gangue minerals. The latter also acts as a fine particle dispersant. Solution pH was kept at 10 using the modifier sodium carbonate (Na2CO3), which can also be regarded as a depressant. Berol 2015 was used as the collector. Four concentrate fractions were collected after 0.75 min (CA), 1.50 min (CB), 3.00 min (CC), and 6.00 min (CD). In addition, a final tailings sample was collected (TD). Five replicates of the test were done to ensure reproducibility and produce enough sample mass for detailed characterization. All samples, including the feed, were wet sieved into four size fractions (-20 µm, +20 to -32 µm, +32 to -50 µm, and +50 µm) before characterization by MLA at the Helmholtz Institute Freiberg for Resource Technology. Samples were analyzed on a FEI Quanta 650F scanning electron microscope equipped with two Bruker Quantax X-Flash 5030 EDX detectors. The SEM was operated at 25 kV overall electron beam accelerating voltage and Extended BSE Liberation Analysis measurement mode. MLA results were validated with ICP-OES chemical assays. Particles from the flotation product samples (concentrate and tailings) are in the Traindata.csv file, while particles from the feed sample are in the FeedData.csv file. The weight distribution of each sample is given below:

Sample | wt.%

CA -20µm | 6.7

CA 20-32µm | 5.8

CA 32-50µm | 4.6

CA +50µm | 2.2

CB -20µm | 6.4

CB 20-32µm | 5.4

CB 32-50µm | 3.9

CB +50µm | 2.8

CC -20µm | 5.8

CC 20-32µm | 4.3

CC 32-50µm | 3.5

CC +50µm | 2.0

CD -20µm | 4.7

CD 20-32µm | 2.8

CD 32-50µm | 2.3

CD +50µm | 1.1

TD -20µm | 11.3

TD 20-32µm | 7.0

TD 32-50µm | 6.7

TD +50µm | 10.7

Feed -20µm | 36.60

Feed 20-32µm | 23.88

Feed 32-50µm | 21.75

Feed +50µm | 17.78

Variable names:

  • Mineral composition: Actinolite, Albite, Almandine, Apatite, Barite, Biotite, Calcite, Chalcopyrite, Clinochlore, Diopside, Dolomite, Fluorite, Hematite, Muscovite, Orthoclase, Plagioclase, Phlogopite, Pyrite, Pyrrhotite, Quartz, Rutile, Sanidine, Sphalerite_Fe, Titanite, Zircon.
  • Surface composition: Actinolite.surf, Albite.surf, Almandine.surf, Apatite.surf, Barite.surf, Biotite.surf, Calcite.surf, Chalcopyrite.surf, Clinochlore.surf, Diopside.surf, Dolomite.surf, Fluorite.surf, Hematite.surf, Muscovite.surf, Orthoclase.surf, Plagioclase.surf, Phlogopite.surf, Pyrite.surf, Pyrrhotite.surf, Quartz.surf, Rutile.surf, Sanidine.surf, Sphalerite_Fe.surf, Titanite.surf, Zircon.surf
  • Size and shape: AspectRatio, Solidity, ECD
  • Sample identifier: Class - In this case, particles identified with "CA20", for example, are the particles from the <20µm size fraction of the first concentrate sample, while "TD50" are the particles from the >50µm size fraction of the final tailings sample.

Keywords: Apatite; Froth flotation; Automated mineralogy; Geometallurgy; Particle-tracking

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Permalink: https://www.hzdr.de/publications/Publ-31592
Publ.-Id: 31592


Technetium immobilization by chukanovite and its oxidative transformation products: Neural network analysis of EXAFS spectra

Schmeide, K.; Roßberg, A.; Bok, F.; Shams Aldin Azzam, S.; Weiß, S.; Scheinost, A.

The uptake of the fission product technetium (Tc) by chukanovite, an Fe(II) hydroxy carbonate mineral formed as a carbon steel corrosion product in anoxic and carbonate-rich environments, was studied under anoxic, alkaline to hyperalkaline conditions representative for nuclear waste repositories in deep geological formations with cement-based inner linings. The retention potential of chukanovite towards Tc(VII) is high in the pH range 7.8 to 12.6, evidenced by high solid-water distribution coefficients, log Rd ~ 6, and independent of ionic strength (0.1 or 1 M NaCl). Using Tc K-edge X-ray absorption spectroscopy (XAS) two series of samples were investigated, Tc chukanovite sorption samples and coprecipitates, prepared with varying Tc loadings, pH values and contact times. From the resulting 37 XAS spectra, spectral endmembers and their dependence on chemical parameters were derived by self-organizing (Kohonen) maps (SOM), a neural network-based approach of machine learning. X-ray absorption near-edge structure (XANES) data confirmed the complete reduction of Tc(VII) to Tc(IV) by chukanovite under all experimental conditions. Consistent with mineralogical phases identified by X-ray diffraction (XRD), SOM analysis of the extended X-ray absorption fine-structure (EXAFS) spectra revealed the presence of three species in the sorption samples, the speciation predominately controlled by pH: Between pH 7.8 and 11.8, TcO₂-dimers form inner-sphere sorption complexes at the surface of the initial chukanovite as well as on the surface of secondary magnetite formed due to redox reaction. At pH ≥11.9, Tc(IV) is incorporated in a mixed, chukanovite-like, Fe/Tc hydroxy carbonate precipitate. The same species formed when using the coprecipitation approach. Reoxidation of sorption samples resulted in a small remobilization of Tc, demonstrating that both the original chukanovite mineral and its oxidative transformation products, magnetite and goethite, contribute to the immobilization of Tc in the long term, thus strongly attenuating its environmental transport.

Keywords: chukanovite; XRD; XAS; incorporation; adsorption; redox; goethite; magnetite; machine learning

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Permalink: https://www.hzdr.de/publications/Publ-31591
Publ.-Id: 31591


Transient CFD Modeling of Matte Settling Behavior and Coalescence in an Industrial Copper Flash Smelting Furnace Settler

Schmidt, A.; Montenegro, V.; Wehinger, G. D.

Copper losses into slag within the flash furnace settler is an economically important topic for the primary copper production. Since the settler is not easily accessible to experimental studies due to harsh reaction conditions, numerical simulations are a promising alternative to obtain more insights into the settling behavior of matte. This study aims to increase the process understanding by developing a CFD flash furnace settler model of an industrial flash furnace. Thereby, the CFD model accounts for bath level changes, polydispersity and coalescence of matte. Coalescence is modeled by an own empirical model focusing on gravitational coalescence. Matte settling shows size-dependent sedimentation within the slag layer, as supported by an own sampling study. Lowering the slag viscosity by a third decreases the copper loss by approximately 37%, while slightly increasing it leads to comparable results. Finally, average copper losses of 0:98wt.% are estimated, finding good agreement with industrial data.

Keywords: Flash Smelting Furnace Settler; Matte Coalescence; Copper Loss; CFD

Permalink: https://www.hzdr.de/publications/Publ-31590
Publ.-Id: 31590


Raw data: Magnetic field-induced even-order harmonic generation in the three-dimensional Dirac semimetal Cd3As2

Deinert, J.-C.

Raw files from the TELBE beamtime August 2020 for exchange.

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Publ.-Id: 31589


Interactive results viewer: Computing single-particle flotation kinetics using automated mineralogy data and machine learning

Pereira, L.; Frenzel, M.; Hoang, D. H.; Tolosana Delgado, R.; Rudolph, M.; Gutzmer, J.

This plotting application allows the reader to interact with all results obtained in the case study presented in the publication

"Computing single-particle flotation kinetics using automated mineralogy data and machine learning", submitted on 07/10/2020 to Minerals Engineering and currently under review.

The interactive plot displays the flotation kinetics modelling outcome (k, Rmax, km) for single-particles. The user is able to filter particles according to their intrinsic properties (modal composition, surface composition, size, and shape), thus allowing the user to understand the influence of every particle property in their process (i.e. flotation) behavior.

The platform contains a help function to guide the user.

It can be accessed here: Pereira et al. 2021 Flotation kinetics platform.

Keywords: Geometallurgy; Particle-tracking; Froth flotation; Automated mineralogy

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Publ.-Id: 31588


Results of a randomized controlled phase III trial: efficacy of polyphenol-containing cystus® tea mouthwash solution for the reduction of mucositis in head and neck cancer patients undergoing external beam radiotherapy

Ebert, N.; Kensche, A.; Löck, S.; Hadiwikarta, W. W.; Hänsch, A.; Dörr, W.; Krause, M.; Hannig, C.; Baumann, M.

Purpose: To determine the effect of Cystus® tea (Naturprodukte Dr. Pandalis GmbH & Co. KG) as mouthwash compared to sage tea on oral mucositis in patients undergoing radio(chemo)therapy for head and neck cancer. Methods: In this randomized, prospective phase III study, 60 head and neck cancer patients with primary or postoperative radio(chemo)therapy were included between 04/2012 and 06/2014. They received either sage or Cystus® tea for daily mouthwash under therapy. Mucositis was scored twice a week following the Radiation Therapy Oncology Group and the European Organization for Research and Treatment Cancer (RTOG/EORTC) scoring system. Dental parameters were also recorded. Statistical evaluation of the primary endpoint was performed using t test and log rank test. Results: Data from 57 patients could be evaluated. Patient characteristics showed no significant difference between the two groups (n = 27 sage; n = 30 Cystus®). A total of 55 patients received the prescribed dose (60–66 Gy postoperative; 70–76.8 Gy primary). Mucositis grade 3 was observed in 23 patients (n = 11 sage; n = 12 Cystus®) and occurred between day 16 and 50 after start of therapy. There was no significant difference between the two groups in latency (p = 0.75) and frequency (p = 0.85) of the occurrence of mucositis grade 3. The self-assessment of the oral mucosa and the tolerability of the tea also showed no significant differences. Occurrence of dental pathologies appeared to increase over time after radiotherapy. Conclusion: Cystus® and sage tea have a similar effect on the occurrence of radiation-induced mucositis regarding latency and incidence. Cystus® tea mouthwash solution is tolerated well and can be applied in addition to intensive oral care and hygiene along with the application of fluorides. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.

Keywords: Herbal tea; HNSC; COral mucositis; Radiation side effect; Supportive treatment

Permalink: https://www.hzdr.de/publications/Publ-31587
Publ.-Id: 31587


BGM MLA data from grinding kinetics experiments

Belo Fernandes, I.

Datasource from two sets of grinding experiments:

- from top size fraction -1600µm+1250µm

- from top size fraction -425µm+315µm

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Publ.-Id: 31586


Long-range magnetic order in the S = 1/2 triangular lattice antiferromagnet KCeS2

Bastien, G.; Rubrecht, B.; Haeussler, E.; Schlender, P.; Zangeneh, Z.; Avdoshenko, S.; Sarkar, R.; Alfonso, A.; Luther, S.; Onykiienko, Y. A.; Walker, H. C.; Kühne, H.; Grinenko, V.; Guguchia, Z.; Kataev, V.; Klauss, H.-H.; Hozoi, L.; van den Brink, J.; Inosov, D. S.; Büchner, B.; Wolter, A. U. B.; Doert, T.

Recently, several putative quantum spin liquid (QSL) states were discovered in S󠆶 = 1/2 rare-earth based triangular-lattice antiferromagnets (TLAF) with the delafossite structure. In order to elucidate the conditions for a QSL to arise, we report here the discovery of a long-range magnetic order in the Ce-based TLAF KCeS2 below TN = 0.38 K, despite the same delafossite structure. Finally, combining various experimental and computational methods, we characterize the crystal electric field scheme, the magnetic anisotropy and the magnetic ground state of KCeS2.

Permalink: https://www.hzdr.de/publications/Publ-31585
Publ.-Id: 31585


2D MOFs: A New Platform for Optics?

Arora, H.; Park, S.; Dong, R.; Erbe, A.

With the research on inorganic 2D semiconductors reaching its zenith, the search for new materials beyond these traditional 2D materials is at a rapid pace. In this article, we present an emerging class of 2D semiconductors, so-called metal-organic frameworks, in terms of their synthesis, intrinsic properties, and underlying charge transport mechanisms. Further, we discuss their potential as active elements in optical applications.

Keywords: Metal-organic frameworks; Two-dimensional semiconductors; Photonics; optical applications; photodetectors; high-mobility materials; sensors

Permalink: https://www.hzdr.de/publications/Publ-31584
Publ.-Id: 31584


Protonen als Alternative zur konventionellen Strahlentherapie – Unterschiede und Herausforderungen

Spautz, S.; Stützer, K.

Die externe Strahlentherapie ist eine wesentliche Komponente bei der Behandlung von Tumoren. Üblicherweise wird dafür Photonenstrahlung verwendet. Jedoch hat sich die Protonentherapie auf Grund ihrer physikalischen Eigenschaften zu einer attraktiven Alternative entwickelt. Vor allem ihre überlegene Dosisverteilung ermöglicht im Vergleich zur herkömmlichen Strahlentherapie eine bessere Normalgewebsschonung, wodurch potentiell das Risiko von Nebenwirkungen und Toxizitäten sinkt. Wir geben hier einen einleitenden Überblick zu den physikalischen Protoneneigenschaften und den Möglichkeiten der Dosisformierung. Insbesondere werden auch spezielle Herausforderungen in der Protonentherapie und damit verbundene aktuelle Forschungsschwerpunkte vorgestellt.

Keywords: Protonentherapie; Physikalische Grundlagen; Herausforderungen; Forschungsschwerpunkte

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Publ.-Id: 31582


Optimal allocation of proton therapy slots in combined proton-photon radiotherapy

Loizeau, N.; Fabiano, S.; Papp, D.; Stützer, K.; Jakobi, A.; Bandurska-Luque, A.; Troost, E. G. C.; Richter, C.; Unkelbach, J.

Purpose: Proton therapy is a limited resource, which is not available to all patients who may benefit from it. We investigate combined proton-photon treatments, in which some fractions are delivered with protons and the remaining fractions with photons, as an approach to maximize the benefit of limited proton therapy resources at a population level.
Methods: To quantify differences in normal tissue complication probability (NTCP) between protons and photons, we consider a cohort of 45 head-and-neck cancer patients for which IMRT and IMPT plans were previously created, in combination with NTCP models for xerostomia and dysphagia considered in the Netherlands for proton patient selection. Assuming limited availability of proton slots, we develop methods to optimally assign proton fractions in combined proton-photon treatments to minimize the average NTCP on a population level. Such combined treatments are compared to patient selection strategies in which patients are assigned to single-modality proton or photon treatments.
Results: There is a benefit of combined proton-photon treatments over patient selection due to the nonlinearity of NTCP functions, i.e. the initial proton fractions are the most beneficial whereas additional proton fractions have a decreasing benefit when a flatter part of the NTCP curve is reached. This effect was small for the patient cohort and NTCP models considered, but may be larger if dose-response relationships are better known. In addition, when proton slots are limited, patient selection methods face a tradeoff between leaving slots unused and blocking slots for future patients who may have a larger benefit. Combined proton-photon treatments with flexible proton slot assignment provide a method to make optimal use of all available resources.
Conclusions: Combined proton-photon treatments allow for a better utilization of limited proton therapy resources. The benefit over patient selection schemes depends on the NTCP models and the dose differences between protons and photons.

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Publ.-Id: 31581


The quantification of entropy for multicomponent systems: application to microwave-assisted comminution

Belo Fernandes, I.; Rudolph, M.; Hassanzadehmahaleh, A.; Bachmann, K.; Meskers, C. E. M.; Peuker, U.; Reuter, M.

The second law of thermodynamics, through exergy analysis, is commonly applied to quantify process inefficiencies in metallurgical reactors, however, it is not yet being used to understand physical processes and changes in particle-based systems. Correlating the state of mixing of particle texture and homogeneous liquid mixtures is of importance. This paper applies the exergy analysis and excess entropy method to two sets of experiments highlighting the differential breakage as microwave pre-treatment is applied to a gold-copper ore. Grinding kinetic properties were measured following the top-size fraction method and calculated using the population balance model. The approach combines the mixing entropy on the system level (streams) and the entropy for multicomponent particle systems, using automated mineralogy data to quantify the effects of intergrowth and improvements in grinding performance. This is a first step towards understanding mineral processing not only in terms of energy conservation (first law of thermodynamics) but also in terms of the quality of energy available at multicomponent systems (second law of thermodynamics). When applied to comminution processes, this methodology enables us to understand the change in particle composition (its degree of liberation) as well as changes in particle size, being an important measure of process efficiency and selectivity.

Keywords: Excess entropy analysis; Exergy distribution; Mineral liberation; Microwave-assisted breakage; Grinding kinetics

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Publ.-Id: 31580


New reaction rates for the destruction of 7Be during big bang nucleosynthesis measured at CERN/n_TOF and their implications on the cosmological lithium problem

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

New measurements of the 7Be(n,α)4He and 7Be(n,p)7Li reaction cross sections from thermal to keV neutron energies have been recently performed at CERN/n_TOF. Based on the new experimental results, astrophysical reaction rates have been derived for both reactions, including a proper evaluation of their uncertainties in the thermal energy range of interest for big bang nucleosynthesis studies. The new estimate of the 7Be destruction rate, based on these new results, yields a decrease of the predicted cosmological 7Li abundance insufficient to provide a viable solution to the cosmological lithium problem.

Permalink: https://www.hzdr.de/publications/Publ-31579
Publ.-Id: 31579


Status and perspectives of the neutron time-of-flight facility n_TOF at CERN

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

Since the start of its operation in 2001, based on an idea of Prof. Carlo Rubbia [1], the neutron time of-flight facility of CERN, n_TOF, has become one of the most forefront neutron facilities in the world for wide-energy spectrum neutron cross section measurements. Thanks to the combination of excellent neutron energy resolution and high instantaneous neutron flux available in the two experimental areas, the second of which has been constructed in 2014, n_TOF is providing a wealth of new data on neutron-induced reactions of interest for nuclear astrophysics, advanced nuclear technologies and medical applications. The unique features of the facility will continue to be exploited in the future, to perform challenging new measurements addressing the still open issues and long-standing quests in the field of neutron physics. In this document the main characteristics of the n_TOF facility and their relevance for neutron studies in the different areas of research will be outlined, addressing the possible future contribution of n_TOF in the fields of nuclear astrophysics, nuclear technologies and medical applications. In addition, the future perspectives of the facility will be described including the upgrade of the spallation target, the setup of an imaging installation and the construction of a new irradiation area.

Permalink: https://www.hzdr.de/publications/Publ-31578
Publ.-Id: 31578


Measurement of the energy-differential cross-section of the 12C(n,p)12B and 12C(n,d)11B reactions at the n_TOF facility at CERN

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

Although the 12C(n,p)12B and 12C(n,d)11B reactions are of interest in several fields of basic and applied Nuclear Physics the present knowledge of these two cross-sections is far from being accurate and reliable, with both evaluations and data showing sizable discrepancies. As part of the challenging n_TOF program on (n,cp) nuclear reactions study, the energy differential cross-sections of the 12C(n,p)12B and 12C(n,d)11 B reactions have been measured at CERN from the reaction thresholds up to 30 MeV neutron energy. Both measurements have been recently performed at the long flight-path (185 m) experimental area of the n_TOF facility at CERN using a pure (99.95%) rigid graphite target and two silicon telescopes. In this paper an overview of the experiment is presented together with a few preliminary results.

Permalink: https://www.hzdr.de/publications/Publ-31577
Publ.-Id: 31577


Measurement of the 242Pu(n, γ) cross section from thermal to 500 keV at the Budapest research reactor and CERN n_TOF-EAR1 facilities

Lerendegui-Marco, J.; Guerrero, C.; Mendoza, E.; Quesada, J. M.; Eberhardt, K.; Junghans, A.; Krtiička, M.; Belgya, T.; Maróti, B.; Aberle, O.; Andrzejewski, J.; Audouin, L.; Bécares, V.; Bacak, M.; Balibrea, J.; Barbagallo, M.; Barros, S.; Bečvář, F.; Beinrucker, C.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brugger, M.; Caamaño, M.; Calviño, F.; Calviani, M.; Cano-Ott, D.; Cardella, R.; Casanovas, A.; Castelluccio, D. M.; Cerutti, F.; Chen, Y. H.; Chiaveri, E.; Colonna, N.; Cortés, G.; Cortés-Giraldo, M. A.; Cosentino, L.; Damone, L. A.; Diakaki, M.; Domingo-Pardo, C.; Dressler, R.; Dupont, E.; Durán, I.; Fernández-Domínguez, B.; Ferrari, A.; Ferreira, P.; Finocchiaro, P.; Furman, V.; Göbel, K.; García, A. R.; Gawlik, A.; Glodariu, T.; Gonçalves, I. F.; González-Romero, E.; Goverdovski, A.; Griesmayer, E.; Gunsing, F.; Harada, H.; Heftrich, T.; Heinitz, S.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Käppeler, F.; Kadi, Y.; Katabuchi, T.; Kavrigin, P.; Ketlerov, V.; Khryachkov, V.; Kimura, A.; Kivel, N.; Knapova, I.; Kokkoris, M.; Leal-Cidoncha, E.; Lederer, C.; Leeb, H.; Lo Meo, S.; Lonsdale, S. J.; Losito, R.; Macina, D.; Marganiec, J.; Martínez, T.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Matteucci, F.; Maugeri, E. A.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Montesano, S.; Musumarra, A.; Nolte, R.; Oprea, A.; Patronis, N.; Pavlik, A.; Perkowski, J.; Porras, J. I.; Praena, J.; Rajeev, K.; Rauscher, T.; Reifarth, R.; Riego-Perez, A.; Rout, P. C.; Rubbia, C.; Ryan, J. A.; Sabaté-Gilarte, M.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Sedyshev, P.; Smith, A. G.; Stamatopoulos, A.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vescovi, D.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Warren, S.; Weigand, M.; Weiss, C.; Wolf, C.; Woods, P. J.; Wright, T.; Žugec, P.; The N_TOF Collaboration

The design and operation of innovative nuclear systems requires a better knowledge of the capture and fission cross sections of the Pu isotopes. For the case of capture on 242Pu, a reduction of the uncertainty in the fast region down to 8-12% is required. Moreover, aiming at improving the evaluation of the fast energy range in terms of average parameters, the OECD NEA High Priority Request List (HPRL) requests high-resolution capture measurements with improved accuracy below 2 keV. The current uncertainties also affect the thermal point, where previous experiments deviate from each other by 20%. A fruitful collaboration betwen JGU Mainz and HZ Dresden-Rossendorf within the EC CHANDA project resulted in a 242Pu sample consisting of a stack of seven fission-like targets making a total of 95(4) mg of 242Pu electrodeposited on thin (11.5 μm) aluminum backings. This contribution presents the results of a set of measurements of the 242Pu(n, γ) cross section from thermal to 500 keV combining different neutron beams and techniques. The thermal point was determined at the Budapest Research Reactor by means of Neutron Activation Analysis and Prompt Gamma Analysis, and the resolved (1 eV - 4 keV) and unresolved (1 - 500 keV) resonance regions were measured using a set of four Total Energy detectors at the CERN n_TOF-EAR1.

Permalink: https://www.hzdr.de/publications/Publ-31576
Publ.-Id: 31576


Co(NO3)2 as an inverted umbrella-type chiral noncoplanar ferrimagnet

Danilovich, I. L.; Deeva, E. B.; Bukhteev, K. Y.; Vorobyova, A. A.; Morozov, I. V.; Volkova, O. S.; Zvereva, E. A.; Maximova, O. V.; Solovyev, I. V.; Nikolaev, S. A.; Phuyal, D.; Abdel-Hafiez, M.; Wang, Y. C.; Lin, J.-Y.; Chen, J. M.; Gorbunov, D.; Puzniak, K.; Lake, B.; Vasiliev, A. N.

The low-dimensional magnetic systems tend to reveal exotic spin-liquid ground states or form peculiar types of long-range order. Among systems of vivid interest are those characterized by the triangular motif in two dimensions. The realization of either ordered or disordered ground state in triangular, honeycomb, or kagome lattices is dictated by the competition of exchange interactions, also being sensitive to anisotropy and the spin value of magnetic ions.While the low-spin Heisenberg systems may arrive to a spin-liquid long-range entangled quantum state with emergent gauge structures, the high-spin Ising systems may establish the rigid noncollinear structures. Here, we present the case of chiral noncoplanar inverted umbrella-type ferrimagnet formed in cobalt nitrate Co(NO3)2 below TC = 3 K with the comparable spin and orbital contributions to the total magnetic moment.

Permalink: https://www.hzdr.de/publications/Publ-31575
Publ.-Id: 31575


Recent progress in contact, mobility, and encapsulation engineering of InSe and GaSe

Arora, H.; Erbe, A.

The field of two-dimensional (2D) materials has stimulated considerable interest in the scientific community. Owing to quantum confinement in one direction, intriguing properties have been reported in 2D materials that cannot be observed in their bulk form. The advent of semiconducting 2D materials with a broad range of electronic properties has provided fascinating opportunities to design and configure next-generation electronics. One such emerging class is the family of III–VI monochalcogenides, the two prominent members of which are indium selenide (InSe) and gallium selenide (GaSe). In contrast to transition metal dichalcogenides (TMDCs), their high intrinsic mobility and the availability of a direct bandgap at small thicknesses have attracted researchers to investigate the underlying physical phenomena as well as their technological applications. However, the sensitivity of InSe and GaSe to environmental influences has limited their exploitation in functional devices. The lack of methods for their scalable synthesis further hinders the realization of their devices. This review article outlines recent advancements in the synthesis and understanding of the charge transport properties of InSe and GaSe for their integration into technological applications. A detailed summary of the improvements in the device structure by optimizing extrinsic factors such as bottom substrates, metal contacts, and device fabrication schemes is provided. Furthermore, various encapsulation techniques that have been proven effective in preventing the degradation of InSe and GaSe layers under ambient conditions are thoroughly discussed. Lastly, this article presents an outlook on future research ventures with respect to ongoing developments and practical viability of these materials.

Keywords: 2D materials; indium selenide; gallium selenide; electronic properties; vdW semiconductors; 2D transistors

Permalink: https://www.hzdr.de/publications/Publ-31574
Publ.-Id: 31574


Dataset for: Morphology of flashing feeds at critical fluid properties in larger pipes

Döß, A.; Schubert, M.; Hampel, U.
DataManager: Wiezorek, Michael

This data set contains cross-sectional averaged vapor fraction data obtained for flashing refrigerant in the horizontal feed section (inner pipe diameter of 200 mm) of the TERESA facility. The data was obtained with the Wire-mesh Sensor Framework GUI (Version 1.3.0). The archive 'void' contains .epst-files which are organized as a two column table (ASCII). The first column denotes the time step (in seconds), the second column is the cross-sectional averaged vapor fraction in percent.

Allocation of the files to the operational conditions is included separate .csv-file (overview.csv), which contains 12 columns for each measurement. Here the averaged values of the .epst-files are included as well.

In this study, two wire-mesh sensors were operated simultaneously. WMS1 (*_X_Sensor_1.epst) was located in an axial distance of L = 2.5 D from the flash nozzle and WMS2 (*_Y_Sensor_2.epst) was located L = 17.5 D away from the flash nozzle.  

Keywords: TERESA; Flashing feed; Wire-mesh sensor

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Publ.-Id: 31573


Detection of REEs with lightweight UAV-based hyperspectral imaging.

Booysen, R.; Jackisch, R.; Lorenz, S.; Zimmermann, R.; Kirsch, M.; Nex, P. A. M.; Gloaguen, R.

Rare Earth Elements (REEs) supply is important to ensure the energy transition, e-mobility and ultimately to achieve the sustainable development goals of the United Nations. Conventional exploration techniques usually rely on substantial geological field work including dense in-situ sampling with long delays until provision of analytical results. However, this approach is limited by land accessibility, financial status, climate and public opposition. Efficient and innovative methods are required to mitigate these limitations. The use of lightweight Unmanned Aerial Vehicles (UAVs) provides a unique opportunity to conduct rapid and non-invasive exploration even in socially sensitive areas and in relatively inaccessible locations. We employ drones with hyperspectral sensors to detect REEs at the Earth’s surface and thus contribute to a rapidly evolving field at the cutting edge of exploration technologies. We showcase for the first time the direct mapping of REEs with lightweight hyperspectral UAV platforms. Our solution has the advantage of quick turn-around times (<1d), low detection limits (<200ppm for Nd) and is ideally suited to support exploration campaigns. This procedure was successfully tested and validated in two areas: Marinkas Quellen, Namibia, and Siilinjärvi, Finland. This strategy should invigorate the use of drones in exploration and for the monitoring of mining activities.

Permalink: https://www.hzdr.de/publications/Publ-31572
Publ.-Id: 31572


Reducing entrainment in ultrafine particle flotation by selective flocculation of gangue material

Sygusch, J.; Rudolph, M.

Froth flotation is an efficient and well-established separation technique for particles with sizes ranging from 10 µm to 200 µm, but when it comes to the separation of ultrafine particles (< 10 µm) there are still some challenges. This research is part of the German research foundation priority programme DFG-SPP 2045 “MehrDimPart” and aims at developing a method for the separation of ultrafine particles based on multiple particle properties, such as wettability, morphology (shape or roughness) and size. In this study, the focus lies on the investigation of the effect of particle size on the flotation outcome.
A system consisting of ultrafine size fractions of glass particles as the valuable material and magnetite as the gangue material is used for testing. Wettability analysis is carried out using inverse gas chromatography, whereas size and shape properties are obtained via a combination of laser diffraction and microscopic analysis. In order to investigate the effect of particle size, the magnetite is selectively flocculated using macromolecules as flocculants. A novel flotation apparatus, designed for the flotation of ultrafine particles by combining advantages from column flotation and machine-type froth flotation, is used for all flotation tests.

Keywords: Ultrafine Particles; Flotation; Selective flocculation; Entrainment

  • Poster (Online presentation)
    10. ProcessNet-Jahrestagung und 34. DECHEMA-Jahrestagung der Biotechnologen 2020, 21.-24.09.2020, Online, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-31571
Publ.-Id: 31571


Zur Mineralogie von Vulkaniten und Lithophysen im Bereich des unterpermischen Leisniger Porphyrs (Nordwestsächsisches Becken)

Götze, J.; Möckel, R.; Breitkreuz, C.; Georgi, U.; Klein, A.

Mineralogische und geochemische Untersuchungen an Proben des Leisniger Porphyrs sowie von Gangporphyren, Pechsteinen und Lithophysen (Hochtemperatur-Kristallisationsdomänen) im entsprechenden Verbreitungsgebiet wurden durchgeführt, um eine mineralogisch-petrographische Charakteristik dieser vulkanischen Bildungen und deren Zuordnung zu möglichen vulkanischen Edukten zu erarbeiten. Phasenanalytische Untersuchungen (Röntgendiffraktometrie, Mikroskopie, Kathodolumineszenz - KL) erbrachten eine monotone Mineralzusammensetzung, die von Quarz, den beiden Kalifeldspat-Phasen Sanidin und Orthoklas sowie Biotit dominiert ist. Anhand der geochemischen Charakteristika (Röntgenfluoreszenzanalyse - RFA) lassen sich die untersuchten Vulkanite überwiegend als Rhyolithe einstufen. Das Vorkommen von hypidiomorphen Quarzphänokristen, z.T. mit Einbuchtungen, gut erhaltenen Kalifeldspäten, sowie das Fehlen von Glas-Shards und Fiamme (Bimsfetzen) deuten darauf hin, dass es sich bei den vulkanischen Ablagerungen im Untersuchungsgebiet um keine Pyroklastite (Ignimbrite) handelt. Neuere Untersuchungen (Rehda 2018) gehen davon aus, dass es sich bei den Gesteinen nicht um klassische Fließlaven handelt, sondern um einen Lakkolith, der sich unter den Rochlitz-Ignimbrit eingeschoben hat. Damit müsste auch die bisherige stratigraphische Einordnung des Leisniger Porphyrs in die KohrenFormation korrigiert werden und eine Einordnung in die frühe Oschatz-Formation erfolgen. Die deutlichen Übereinstimmungen aller Gesteinstypen hinsichtlich mineralogischer Zusammensetzung, chemischer Charakteristik, Ausbildung der Phänokristen sowie deren KL-Eigenschaften deuten auf die Herkunft aus einem gemeinsamen Magmenreservoir hin. Auftretende Unterschiede sind im Wesentlichen auf sekundäre Alterationen zurückzuführen. Allerdings zeigen Geländebefunde und vertikal ausgerichtete Gefüge in Pechsteinen und Gangporphyren, dass diese vulkanischen Bildungen den eigentlichen Leisniger Porphyr wahrscheinlich zu einem späteren Zeitpunkt in Form vertikaler Gangstrukturen durchschlagen haben. Aufgrund der mineralogischen und geochemischen Ähnlichkeiten der Kristallisationsdomänen der Lithophysen und aller Gesteinstypen im Verbreitungsbereich des Leisniger Porphyrs kann bisher keine eindeutige Zuordnung
der Lithophysen- und Achatbildungen zu einer speziellen Gesteinsgruppe erfolgen. Aus Geländebefunden ist eine Häufung in Kreuzungsbereichen von Gangporphyren und Pechsteinen mit dem eigentlichen Leisniger Porphyr zu beobachten, was allerdings im Anstehenden oder in Bohrproben nicht direkt nachgewiesen werden
konnte. Die Bildung der Lithophysen im Bereich einer glasigen Fazies konnte ebenfalls bisher nicht bestätigt werden, da keine randlichen Anhaftungen von Pechsteinrelikten an den Lithophysen (wie im Fall des Kemmlitzer Porphyrs) beobachtet wurden. Auf Grund spezifischer textureller und mineralogischer Unterschiede kann allerdings eine Zuordnung der Lithophysen zum Seifersdorfer Porphyr im Liegenden bzw. zum Rochlitz-Ignimbrit im Hangenden ausgeschlossen werden.

Mineralogical and geochemical investigations were carried out on samples of the Leisnig porphyry including certain vein-like porphyries, pitchstones and lithophysae (HTCD - high temperature crystallization domains) in the distribution area to get information about mineralogical and petrographical characteristics of the volcanic rocks and their origin. Analytical results of X-ray diffraction, microscopy and cathodoluminescence (CL) revealed a monotonous mineral composition dominated by quartz, orthoclase/sanidine and biotite. The volcanic rocks can be classified as rhyolite according to geochemical characteristics (X-ray fluorescence – XRF). Hypidiomorphic quartz phenocrysts, partially with embayments, well preserved K-feldspar, and the absence of glass shards and fiamme disclose a pyroclastic formation (ignimbrite) of the rocks of the Leisnig porphyry in contrast to the Rochlitz ignimbrite in the same area. Recent results of Rehda (2018) indicate that the volcanic rocks of the Leisnig porphyry were not formed by flowing lava, but represent a laccolith that emplaced below the volcanic rocks of the Rochlitz ignimbrite. This consideration would result in a stratigraphic position of the Leisnig porphyry in the early Oschatz Formation instead of the previously assumed position in the Kohren Formation. The common mineralogical and chemical composition of all rock types, as well as similar characteristics of phenocrysts including their CL properties, indicate an origin from the same magma chamber or at least a melt with similar composition. Detected differences can mainly be related to secondary alteration processes. Field observations and vertically oriented textures in pitchstones and vein porphyries show that these volcanic rocks subsequently penetrated the Leisnig porphyry as vertical vein structures. Up to now, no unambiguous assignment of the lithopysae and associated agates can be done to one of the rock types in the distribution area of the Leisnig porphyry because of their similarities in mineralogy and geochemistry with the crystallization domains of the lithophysae. Based on field observations, a preferred occurrence of lithophysae in cross areas of vein porphyries and pitchstones with the Leisnig porphyry is assumed. However, this assumption could not be proven directly in outcrops or drilling samples. Although the formation of lithophysae in a glassy facies is most likely (as it was proven for the Kemmlitz porphyry), this assumption could not be confirmed due to the lack of adherent pitchstone relics on the lithophysae. However, mineralogical and textural differences to the underlying Seifersdorf porphyry and the overlying Rochlitz ignimbrite disclose an assignment of the lithophysae in the area of the Leisnig porphyry to these volcanic rocks.

  • Veröffentlichungen des Museums für Naturkunde Chemnitz 43(2020)-5-44

Permalink: https://www.hzdr.de/publications/Publ-31570
Publ.-Id: 31570


Better Together: Ilmenite/Hematite Junctions for Photoelectrochemical Water Oxidation

Berardi, S.; Kesavan, J. K.; Amidani, L.; Meloni, E. M.; Marelli, M.; Boscherini, F.; Caramori, S.; Pasquini, L.

Hematite (α-Fe₂O₃) is an Earth-abundant indirect n-type semiconductor displaying a band gap of about 2.2 eV, useful for collecting a large fraction of visible photons, with frontier energy levels suitably aligned for carrying out the photoelectrochemical water oxidation reaction under basic conditions. The modification of hematite mesoporous thin film photoanodes with Ti(IV), as well as their functionalization with an oxygen evolving catalyst, leads to a six-fold increase in photocurrent density with respect to the unmodified electrode. In order to provide a detailed understanding of this behavior, we report a study of Ti-containing phases within the mesoporous film structure. Using X-ray absorption fine structure and high-resolution transmission electron microscopy coupled with electron energy loss spectroscopy, we find that Ti(IV) ions are incorporated within ilmenite (FeTiO₃) near-surface layers, thus modifying the semiconductor-electrolyte interface. To the best of our knowledge, this is the first time that a FeTiO₃/α -Fe₂O₃ composite is used in a photoelectrochemical set-up for water oxidation. In fact, previous studies of Ti(IV)-modified hematite photoanodes reported the formation of pseudobrookite (Fe₂TiO₅) at the surface. By means of transient absorption spectroscopy, transient photocurrent experiments, and electrochemical impedance spectroscopy, we show that the formation of the Fe₂O₃/FeTiO₃ interface passivates deep traps at the surface and induce a large density of donor levels, resulting in a strong depletion field that separates electron and holes, favoring hole injection in the electrolyte. Our results provide the identification of a phase coexistence with enhanced photoelectrochemical performance, allowing for the rational design of new photoanodes with improved kinetics.

Keywords: Photoelectrochemistry; Hematite; Titanium; EXAFS; Electron Microscopy; Transient Absorption Spectroscopy; Heterointerface; Oxygen Evolution Catalyst

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Formation and crystallographic orientation of NiSi2-Si interfaces

Fuchs, F.; Khan, B.; Deb, D.; Pohl, D.; Schuster, J.; Weber, W. M.; Mühle, U.; Löffler, M.; Georgiev, Y. M.; Erbe, A.; Gemming, S.

The transport properties of novel device architectures depend strongly on the morphology and the quality of the interface between contact and channel materials. In silicon nanowires with nickel silicide contacts, NiSi 2-Si interfaces are particularly important as NiSi 2 is often found as the phase adjacent to the silicide-silicon interface during and after the silicidation. The interface orientation of these NiSi 2-Si interfaces as well as the ability to create abrupt and flat interfaces, ultimately with atomic sharpness, is essential for the properties of diverse emerging device concepts. We present a combined experimental and theoretical study on NiSi 2-Si interfaces. Interfaces in silicon nanowires were fabricated using silicidation and characterized by high-resolution (scanning) transmission electron microscopy. It is found that {111} interfaces occur in 〈110»nanowires. A tilted interface and an arrow-shaped interface are observed, which depends on the nanowire diameter. We have further modeled NiSi 2-Si interfaces by density functional theory. Different crystallographic orientations and interface variations, e.g., due to interface reconstruction, are compared with respect to interface energy densities. The {111} interface is energetically most favorable, which explains the experimental observations. Possible ways to control the interface type are discussed.

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Publ.-Id: 31568


Detection of manufactured nanomaterials in complex environmental compartments – An expert review

Schymura, S.; Hildebrand, H.; Völker, D.; Schwirn, K.; Franke, K.; Fischer, C.

Manufactured nanomaterials (NMs) are materials in which 50% or more of the particles have one or more dimensions between 1 nm and 100 nm. These NMs show interesting properties. However, the same properties that motivate their use in applications are also reason for concern, as NMs can cause toxic reactions and have mobilities in the environment different from bulk materials of the same elements. Despite considerable scientific efforts, the selective detection of manufactured NMs in environmental compartments is still a very complex and challenging task. An expert review of the literature has been conducted on behalf of the German Environment Agency (UBA) to identify relevant methods for nanomaterial detection in complex media in the context of environmental monitoring and a need for action was concluded from the existing body of work.

Keywords: Nanoparticle detection; Environment; complex systems

  • Poster (Online presentation)
    Nanosafety 2020, 05.-07.10.2020, Saarbrücken, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-31567
Publ.-Id: 31567


Radiolabeling of nanoparticles - A versatile tool in nanosafety research

Schymura, S.; Hildebrand, H.; Rybkin, I.; Strok, M.; Franke, K.

The employment of radiotracers is a versatile tool for the detection of nano-particulate materials in complex systems such as environmental samples or organisms. The monitoring of nanoparticles (NPs) in such complex natural systems as soil, natural waters, plants, sewage sludge, etc. very is challenging using conventional methods, especially at environmentally relevant concentrations. This obstacle can be overcome by the use of radiolabeling which provides an easy way of accurately quantifying nanoparticles in complex systems without extensive sample preparation, regardless of any particulate or elemental background.
We have developed various methods of introducing radiotracers into the most common nanoparticles, such as Ag, carbon, SiO2, CeO2 and TiO2 nanoparticles.

Keywords: Radiolabeling; nanoparticles

  • Poster (Online presentation)
    Nanosafety 2020, 05.-07.10.2020, Saarbrücken, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-31566
Publ.-Id: 31566


Monitoring laser-induced magnetization in FeRh by transient terahertz emission spectroscopy

Awari, N.; Semisalova, A.; Deinert, J.-C.; Lenz, K.; Lindner, J.; Fullerton, E.; Uhlir, V.; Li, J.; Clemens, B.; Carley, R.; Scherz, A.; Kovalev, S.; Gensch, M.

In this study, a conceptually different approach for investigating magnetic phase transitions in ultra-thin films is presented. THz emission from a laser-excited material is used to monitor the magnetization dynamics during the laser-driven antiferromagnetic to ferromagnetic transition in FeRh. The emitted THz signal is calibrated against static magnetometry data measurements, giving a direct measure of the absolute magnetic moment of the sample on the sub-picosecond timescale. The technique is, therefore, highly complementary to conventional time-resolved experiments such as time resolved magneto-optic Kerr effect (MOKE) or x-ray magnetic circular dichroism.

Keywords: Magnetization dynamics; terahertz; ultrafast; FeRh

Permalink: https://www.hzdr.de/publications/Publ-31565
Publ.-Id: 31565


Grating-graphene metamaterial as a platform for terahertz nonlinear photonics

Deinert, J.-C.; Alcaraz Iranzo, D.; Perez, R.; Jia, X.; Hafez, H. A.; Ilyakov, I.; Awari, N.; Chen, M.; Bawatna, M.; Ponomaryov, O.; Germanskiy, S.; Bonn, M.; Koppens, F. H. L.; Turchinovich, D.; Gensch, M.; Kovalev, S.; Tielrooij, K.-J.

Nonlinear optics is an increasingly important field for scientific and technological applications, owing to its relevance and potential for optical and optoelectronic technologies. Currently, there is an active search for suitable nonlinear material systems with efficient conversion and small material footprint. Ideally, the material system should allow for chip-integration and room-temperature operation. Two-dimensional materials are highly interesting in this regard. Particularly promising is graphene, which has demonstrated an exceptionally large nonlinearity in the terahertz regime. Yet, the light-matter interaction length in two-dimensional materials is inherently minimal, thus limiting the overall nonlinear-optical conversion efficiency. Here we overcome this challenge using a metamaterial platform that combines graphene with a photonic grating structure providing field enhancement. We measure terahertz third-harmonic generation in this metamaterial and obtain an effective third-order nonlinear susceptibility with a magnitude as large as 3·10−⁸ m² /V² , or 21 esu, for a fundamental frequencyof 0.7 THz. This nonlinearity is 50 times larger than what we obtain for graphene without grating. Such an enhancement corresponds to third-harmonic signal with an intensity that is three orders of magnitude larger due to the grating. Moreover, we demonstrate a field conversion efficiency for the third harmonic of up to ∼1% using a moderate field strength of ∼30 kV/cm. Finally we show that harmonics beyond the third are enhanced even more strongly, allowing us to observe signatures of up to the 9th harmonic. Grating-graphene metamaterials thus constitute an outstanding platform for commercially viable, CMOS compatible, room temperature, chip-integrated,THz nonlinear conversion applications.

Keywords: terahertz; harmonics; graphene; nonlinear; field enhancement; metamaterial

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Publ.-Id: 31564


Experimental data of the ROCOME2.3 experiment

Kliem, S.
DataManager: Grahn, Alexander

The experiment ROCOM E2.3 represents a boron dilution event in a KONVOI-type pressurized lightwater reactor. It was conducted at room temperature with de-mineralized water without boric acid. Underborated water slugs were modelled by adding Ethanol in order to adjust a density difference of 1.22% with respect to the regular coolant inventory. At the beginning of the experiment, the slugs are enclosed between two valves in the cold legs of loops 1 and 2. The volume of the two water slugs accounts for 0.0576 m 3 (57.6 l) each and the slug fronts are located at 1.8 m upstream of the pressure vessel inlet nozzles. The experiment is started by opening the loop valves and running up the circulation pumps. The time dependency of the volumetric flow rates in all four coolant loops can be found in https://doi.org/10.1016/j.nucengdes.2020.110776. During the experiment, the mixing process was recorded by wire-mesh conductivity sensors at various positions within the coolant loops and the pressure vessel.  The nomenclature of the data files as well as the format of the tables are described in the accompanying document DataDescription_ROCOME23.pdf.

Keywords: boron dilution; coolant mixing; pressurized water reactor

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Permalink: https://www.hzdr.de/publications/Publ-31562
Publ.-Id: 31562


Presence of Bradyrhizobium sp. under continental conditions in Central Europe

Griebsch, A.; Matschiavelli, N.; Lewandowska, S.; Schmidtke, K.

Soil samples from different locations with varied cultivation histories of soybeans were taken from arable fields in 2018 in East Germany and Poland (Lower Silesia) to evaluate the specific microsymbionts of the soybean, Bradyrhizobium japonicum, over the years after inoculation. Soybean was grown in the selected farms between 2011 and 2017. The aim of the experiment is to investigate whether there is a difference in rhizobia content in soils in which soybean was grown over a different period of time and whether this might lead to differences in plant growth of soybean. The obtained soil samples were directly transferred into containers, then sterilized soybean seeds were sown into pots in the greenhouse. After 94 days of growth, the plants were harvested and various parameters such as nodular mass, number of nodules and dry matter in the individual plant parts were determined. In addition, the relative abundance of Bradyrhizobium sp. in soil samples was determined identified by sequencing. No major decline in Bradyrhizobia could be observed due to a longer interruption of soybean cultivation. Soil properties such as pH, P and Mg content had no significant influence on the formation of nodule mass and number, but seem to have an influence on the relative abundance of Bradyrhizobium sp. The investigations have shown that Bradyrhizobium japonicum persists longer in arable soils even under the site conditions of Central Europe and forms an effective symbiosis with soybeans.

Permalink: https://www.hzdr.de/publications/Publ-31561
Publ.-Id: 31561


Zur Untersuchung schwerer Erdalkalimetalle für die radiopharmazeutische Anwendung

Bauer, D.

Ein maßgebliches medizinisches Problem unserer Gesellschaft sind Krebs- und Tumor-erkrankungen. Aus diesem Grund sind die verbesserte Diagnose und Früherkennung von Krebserkrankungen sowie die Entwicklung neuer und effizienterer Therapiemöglichkeiten ein wichtiger Aspekt der gegenwärtigen medizinischen Forschung.
Die zielgerichtete α-Partikel Therapie (TAT, engl. Targeted Alpha-particle Therapy) ist eine spezielle Form der nuklearmedizinischen Behandlung von Krebserkrankungen und ordnet sich im Feld der Radionuklidtherapie ein. Die TAT hebt sich gegenüber anderen Radionuklidtherapien, wie der Behandlung mit β--oder Auger-Elektronen-Emittern, dadurch hervor, dass sie Chemo- und Strahlungsresistenzen überwinden kann, eine hohe biologische Wirksamkeit zeigt, und dabei gesundes Gewebe vergleichsmäßig wenig belastet.
Bei der TAT werden α-emittierende Radionuklide, hauptsächlich Radiometalle, mittels eines Radiopharmakons zielgerichtet an oder in die Krebszellen transportiert, welche dort hochenergetische α-Partikel emittieren, die zum Absterben des entarteten Gewebes führen. Um ein Radiopharmakon auf Basis eines Radiometalls herzustellen, werden die entsprechenden Radionuklide mittels eines Chelators stabil gebunden, welcher wiederum mit einem Vektormolekül verknüpft ist. Vektormoleküle können dabei monoklonale Antikörper oder niedermolekulare Verbindungen sein, welche spezifische Eigenschaften der Krebszelle adressieren und damit das selektive Binden an diese ermöglichen.
Nur wenige α-Emitter erfüllen die Voraussetzungen, um in der TAT eingesetzt werden zu können. Aus der Reihe der schweren Erdalkalimetalle stammen die beiden α-Emitter Radium 223 und Radium-224, welche großes Potential für eine solche radiopharmazeutische Anwendung besitzen. Zusätzlich kann der γ Emitter Barium 131, dessen Element das nächst leichtere Homologe des Radiums ist, zum Therapie-Monitoring eingesetzt werden. Aufgrund der chemischen Ähnlichkeit der Elemente Barium und Radium können beide mittels des gleichen Chelators gebunden und deren Radionuklide im Rahmen eines kombinierten diagnostischen und therapeutischen – eines so genannten theranostischen – Ansatzes in der Onkologie genutzt werden. Da von Radium keine stabilen Isotope existieren, dient Barium auch als ein nicht-radioaktives Surrogat, um Chelatoren initial bezüglich ihrer Komplex-bildungseigenschaften zu untersuchen.
Ziel dieser Arbeit war es, das Potential ausgewählter Radionuklide aus der Gruppe der schweren Erdalkalimetalle für die radiopharmazeutische Anwendung zu erschließen, und dafür die Möglichkeit ihrer stabilen Bindung in einem Radiopharmakon mittels eines geeigneten Chelators zu untersuchen. Der Fokus lag dabei auf Barium 131 und Radium 224. Als potentielle Chelatoren wurden die beiden Substanzklassen der Calix[4]aren-krone-6-Derivate und der Cavitanden untersucht.
Bei diesen Verbindungen handelt es sich um Makrozyklen, welche aus vier aromatischen Einheiten aufgebaut sind. Ihre Anordnung formt eine Kavität, welche auf die Ionengrößen von Barium und Radium zugeschnitten ist. Die beiden Grundstrukturen verfügen jeweils über acht Sauerstoffatome, die für die Koordination an Ba2+- beziehungsweise Ra2+-Ionen, ideale Donoratome darstellen.
Um die Interaktion der Liganden mit (nicht-radioaktiven) Bariumionen untersuchen zu können, wurden analytische Verfahren auf der Basis von NMR- und UV/Vis-Spektroskopie etabliert. Bei diesen Untersuchungen wurde für die Cavitanden trotzt weitreichender Optimierungsversuche keine Einlagerung von Bariumionen festgestellt.
Für die Calix[4]krone-6-basierten Derivate wurden die entsprechenden 1:1 Metallion-Ligand-Chelate mit Bariumionen hergestellt und nachgewiesen. Die Stabilität der Chelate wurde mit einer Titrationsmethode auf Basis von NMR- und UV/Vis Detektion bestimmt. Aufgrund der geringen Wasserlöslichkeit der gewählten Verbindungen wurden die initialen Versuche im Lösungsmittel Acetonitril durchgeführt. In nachfolgenden Optimierungsschritten wurden Calix[4]krone-6-basierte Chelatoren hergestellt, welche in Hinblick auf das HSAB-Konzept noch besser auf schwere Erdalkalimetalle abgestimmt waren. Zusätzlich wurden diese Chelatoren über funktionelle Gruppen mit einem Vektormolekül verknüpft, welches die Wasserlöslichkeit erhöhte.
Für nachfolgende Radiomarkierungsversuche wurden Dünnschichtchromatographie-Systeme etabliert, welche die Untersuchung von [131Ba]Ba2+- und [224Ra]Ra2+-Chelaten im wässrigen Medium sowie unter kompetitiven Bedingungen ermöglichten. Es konnten jedoch für alle Calix[4]krone-6-Derivate unter wässrigen Bedingungen keine Chelate nachgewiesen werden. Anschließende Untersuchungen legten nahe, dass das Radiometall kinetisch nicht ausreichend stabil in den Calix[4]krone-6-Derivate gebunden ist

Keywords: Radium-223; Barium-131; Makrozyklen; targetd Alpha-Therrapy

  • Doctoral thesis
    TU Dresden, 2020
    Mentor: PD Dr. habil. Constantin Mamat
    162 Seiten

Permalink: https://www.hzdr.de/publications/Publ-31560
Publ.-Id: 31560


Nanocytometer for smart analysis of peripheral blood and acute myeloid leukemia: a pilot study

Schütt, J.; Sandoval Bojorquez, D. I.; Avitabile, E.; Oliveros Mata, E. S.; Milyukov, G.; Colditz, J.; Delogu, L. G.; Rauner, M.; Feldmann, A.; Koristka, S.; Middeke, J. M.; Sockel, K.; Faßbender, J.; Bachmann, M.; Bornhäuser, M.; Cuniberti, G.; Baraban, L.

We realize an ultracompact nanocytometer for real-time impedimetric detection and classification of subpopulations ofliving cells. Nanoscopic nanowires in a microfluidic channel act asnanocapacitors and measure in real time the change of theamplitude and phase of the output voltage and, thus, the electricalproperties of living cells. We perform the cell classification in thehuman peripheral blood (PBMC) and demonstrate for thefirsttime the possibility to discriminate monocytes andsubpopulationsof lymphocytes in a label-free format. Further, we demonstrate thatthe PBMC of acute myeloid leukemia and healthy samples grantthe label free identification of the disease. Using the algorithmbased on machine learning, we generatedspecific data patternstodiscriminate healthy donors and leukemia patients. Such a solutionhas the potential to improve the traditional diagnostics approaches with respect to the overall cost and time effort, in a label-freeformat, and restrictions of the complex data analysis.

Keywords: mpedance cytometer; nanosensor; POC diagnostics; PBMCs; acute myeloid leukemia (AML); machine learning for data treatment

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Permalink: https://www.hzdr.de/publications/Publ-31558
Publ.-Id: 31558


Tailoring the Electronic and Magnetic Properties of Hematene by Surface Passivation: Insights from First-principles Calculations

Wei, Y.; Ghorbani Asl, M.; Krasheninnikov, A.

Exfoliation of atomically-thin layers from non-van der Waals bulk solids gave rise to the emergence of a new class of two-dimensional (2D) materials, such as hematene (Hm), a structure just a few atoms thick obtained from hematite. Due to a large number of unsaturated sites, Hm surface can be passivated under ambient conditions. Using density functional theory calculations, we investigate the effects of surface passivation with H and OH groups on Hm properties and demonstrate that the passivated surfaces are energetically favorable under oxygen-rich conditions. While the bare sheet is antiferromagnetic and possesses an indirect band gap of 0.93 eV, the hydrogenated sheets are half-metallic with a ferromagnetic ground state, and the fully hydroxylated sheets are antiferromagnetic with a larger band gap as compared to the bare system. The electronic structure of Hm can be further tuned by mechanical deformations. The band gap of fully passivated Hm increases monotonically with biaxial strain, hinting at potential applications of Hm in electromechanical devices.

Keywords: Two-dimensional materials; Hematene; Surface Passivation; First-principles Calculations

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Permalink: https://www.hzdr.de/publications/Publ-31557
Publ.-Id: 31557


Eddy Current Flow Meter performance in liquid metal flows inclined to the sensor axis

Krauter, N.; Galindo, V.; Wondrak, T.; Eckert, S.; Gerbeth, G.

The Eddy Current Flow Meter is a reliable and robust inductive sensor for the measurement of flowrates in liquid metal flows. This kind of sensor is usually being used in pipe flows where the flow is mostly parallel to the sensor axis. When this sensor is used as part of the safety instrumentation above the subassemblies in liquid metal cooled fast reactors, the flow angle may change rapidly according to the conditions within the reactor. In this paper we investigate the performance of the Eddy Current Flow Meter in flows inclined to the sensor axis by numerical simulations as well as model experiments. We demonstrate that the Eddy Current Flow Meter yields reliable results for flow angles up to 30° while the sensitivity of the sensor is significantly reduced for larger angles.

Keywords: inductive measurements; flow velocity; flow angle; Eddy Current Flow Meter

Permalink: https://www.hzdr.de/publications/Publ-31556
Publ.-Id: 31556


Depth selective magnetic phase coexistence in FeRh thin films

Griggs, W.; Eggert, B.; Liedke, M. O.; Butterling, M.; Wagner, A.; Kentsch, U.; Hirschmann, E.; Grimes, M.; Caruana, A. J.; Kinane, C.; Wende, H.; Bali, R.; Thomson, T.

We demonstrate the manipulation of magnetic phasesin FeRh thin filmsthrough atomic displacementsand the distributionof structural defects. Atomic scale disorder can be controlled via irradiation withlight noble gas ions, producingdepth-varying nanoscale phase configurationsof distinct antiferromagnetic, ferromagnetic and paramagnetic regions. Here, we perform a spatial characterization of the magnetic phasesandthe local magnetic environment around the Fe atoms,as well as the variation ofthe open-volumes around atomic sites. Thus,a direct correspondence between the existence of the three magnetic phases andlattice defects is revealed. By careful selection of the irradiating fluence, we show that it is possible to produce simple and thermally stable magnetic configurations, such as uniform magnetisation or a bilayer phase structure.Furthermore, the thin film surface and interfaces are observed as the nucleation sites for the transitions between the phases. These results demonstrate a sensitive nanoscale manipulation of magnetic properties, shedding light on magnetic ordering in alloy lattices and broadening the scope for applications.

Keywords: Magnetic modification; PNR; Induced disorder; Phase transitions; FeRh

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Permalink: https://www.hzdr.de/publications/Publ-31555
Publ.-Id: 31555


Guideline on current good radiopharmacy practice (cGRPP) for the small-scale preparation of radiopharmaceuticals

Gillings, N.; Hjelstuen, O.; Ballinger, J.; Béhé, M.; Decristoforo, C.; Elsinga, P.; Ferrari, V.; Kolenc Peitl, P.; Koziorowski, J.; Laverman, P.; Mindt, T.; Neels, O.; Ocak, M.; Patt, M.; Todde, S.

This guideline on current good radiopharmacy practice (cGRPP) for small-scale preparation of radiopharmaceuticals represents the view of the Radiopharmacy Committee of the European Association of Nuclear Medicine (EANM). The guideline is laid out in the format of the EU Good Manufacturing Practice (GMP) guidelines as defined in EudraLex volume 4. It is intended for non-commercial sites such as hospital radiopharmacies, nuclear medicine departments, research PET centres and in general any healthcare establishments. In the first section, general aspects which are applicable to all levels of operations are discussed. The second section discusses the preparation of small-scale radiopharmaceuticals (SSRP) using licensed generators and kits. Finally, the third section goes into the more complex preparation of SSRP from non-licensed starting materials, often requiring a purification step and sterile filtration. The intention is that the guideline will assist radiopharmacies in the preparation of diagnostic and therapeutic SSRP´s safe for human administration.

Keywords: cGRPP; GMP; radiopharmaceuticals; radiopharmacy

Permalink: https://www.hzdr.de/publications/Publ-31554
Publ.-Id: 31554


Anisotropy of the magnetocaloric effect: Example of Mn5Ge3

Maraytta, N.; Voigt, J.; Salazar Mejia, C.; Friese, K.; Scurschii, I.; Perßon, J.; Salman, S. M.; Brückel, T.

We have investigated the field direction dependence of thermo-magnetic behavior in single crystalline Mn5Ge3. The adiabatic temperature change ΔTad in pulsed fields, the isothermal entropy change ΔSiso calculated from static magnetization measurements, and heat capacity have been determined for fields parallel and perpendicular to the easy magnetic direction [001]. The isothermal magnetization measurements yield, furthermore, the uniaxial anisotropy constants in second and fourth order, K1 and K2. We discuss how the anisotropy affects the magneto-caloric effect (MCE) and compare the results to the related compound MnFe4Si3, which features an enhanced MCE, too, but instead exhibits strong easy plane anisotropy. Our study reveals the importance of magnetic anisotropy and opens new approaches for optimizing the performance of magnetocaloric materials in applications.

Permalink: https://www.hzdr.de/publications/Publ-31553
Publ.-Id: 31553


Pulsed laser deposition of Fe-oxypnictides: Co- and F-substitution

Haindl, S.; Sato, M.; Wurmehl, S.; Büchner, B.; Kampert, W. A. G.

The majority of thin film studies that were devoted to Fe-oxyarsenides has focused so far on F-substituted (i.e. indirectly electron doped) LnOFeAs (Ln = La, Nd, Sm). Here we turn our attention towards Co-substituted (i.e. directly electron doped) LaOFeAs and SmOFeAs in order to investigate its growth on different substrate materials by using pulsed laser deposition (PLD). We detected dominant LnOFeAs phase formation and discuss the occurrence of minor impurity phases in the different films on different substrates. The lack of a superconducting transition in LnOFe0.85Co0.15As films on MgO(100) could be due to strain, since we observe an onset of superconductivity in SmOFe1−xCoxAs (x = 0.07, 0.15) films on other oxide substrates. In addition, Co-substitution (i.e. within the Fe2As2 layers) and F-substitution (i.e. within the Ln2O2 layers) leading to direct and indirect electron doping respectively, appears for films deposited on CaF2 substrates. In contrast to the F-substituted but Co-free Fe-oxyarsenides, the co-doped SmO1−xFxFe0.85Co0.15As film has experimentally accessible upper critical fields down to the lowest temperatures and may serve as an ideal test bed for further theoretical modeling of Fe-oxyarsenides.

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Permalink: https://www.hzdr.de/publications/Publ-31552
Publ.-Id: 31552


Preparation of γ-Al₂O₃/α-Al₂O₃ ceramic foams as catalyst carriers via the replica technique

Shumilov, V.; Kirilin, A.; Tokarev, A.; Boden, S.; Schubert, M.; Hampel, U.; Hupa, L.; Salmi, T.; Murzin, D. Y.

This work describes an effective method for the preparation of open-cell ceramic foams for their further use as catalyst supports. The polyurethane sponge replica technique was applied using a ceramic suspension based on a mixture of α-alumina, magnesia and titania and polyvinyl alcohol solution as a liquid component. The polyurethane sponge was etched with NaOH and covered with colloidal silica to obtain better adhesion of the slurry to the walls of the polymeric material onto it. The surface area of the ceramic carrier was increased by adding a layer of γ-alumina. Deposition of an active catalytic phase (Pt) was done by impregnation. Properties of the carriers and the final catalyst were investigated by a number of physico-chemical methods such as TEM, SEM, XRD and computer tomography. Hydrogenation of ethyl benzoylformate was performed to elucidate the catalytic properties of foam catalysts illustrating their applicability.

Keywords: γ-Al₂O₃/α-Al₂O₃; catalytic foams; macroporous ceramics; hydrogenation of ethylbenzoylformate

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Permalink: https://www.hzdr.de/publications/Publ-31551
Publ.-Id: 31551


Single-Shot Measurement of Post-Pulse-GeneratedPre-Pulse in High-Power Laser Systems

Kon, A.; Nishiuchi, M.; Kiriyama, H.; Kando, M.; Bock, S.; Ziegler, T.; Püschel, T.; Zeil, K.; Schramm, U.; Kondo, K.

In this study, a detailed investigation of the dynamics of the generation of pre-pulse bypost-pulses is presented, using single-shot self-referenced spectral interferometry (SRSI). The capabilityof SRSI in terms of the single-shot measurement of the temporal contrast of high-power lasersystems has been experimentally demonstrated. The results confirm that the energy levels of thepre-pulses increase proportional to the square of the B-integral parametrizing the nonlinearity of theamplifier chain.

Keywords: laser pulse contrast; high-intensity lasers; B-integral

Permalink: https://www.hzdr.de/publications/Publ-31549
Publ.-Id: 31549


Supplementary simulations for laser foil experiments on TOD variation

Göthel, I.

Simulations made with PIConGPU in 2d geometry with a longitudinally modified gaussian laser on a foil.
The laser has been modified to reproduce the main features of the pulse shape seen in the experiments as a result of modifying TOD and GVD.
The three main features, which were enabled with varying strength in the simulations:
 - an exponential ramp on the timescale of 300fs before the gaussian main pulse
 - a postpulse with around 100fs delay and around 0.2 of the total pulse energy
 - a skewness of the gaussian - modelled by two gaussian halves for the rising and falling part

From the spectra of the accelerated protons the cutoff energy is measured. The main result is, that the variations of the spectra are much smaller than those observed in the experiments, suggesting more complex mechanisms than those modelled here.

Keywords: laser particle acceleration

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Permalink: https://www.hzdr.de/publications/Publ-31548
Publ.-Id: 31548


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