Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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41652 Publications

Position Paper to facilitate patient access to radiopharmaceuticals - considerations for a suitable pharmaceutical regulatory framework

Korde, A.; Patt, M.; Selivanova, S.; Scott, A.; Hesselmann, R.; Kiß, O.; Ramamoorthy, N.; Todde, S.; Rubow, S.; Gwaza, L.; Lyashchenko, S.; Andersson, J.; Hockley, B.; Kaslival, R.; Decristoforo, C.

Abstract

Nuclear medicine has made enormous progress in the past decades. However, there are still significant inequalities in patient access among different countries, which could be mitigated by a suitable pharmaceutical regulatory framework and associated guidelines. This paper summarizes major considerations for a suitable pharmaceutical regulatory framework to facilitate patient access to radiopharmaceuticals. These include the distinct characteristics of radiopharmaceuticals advocating dedicated regulations, the impact of variable complexity of radiopharmaceutical preparation, personnel requirements, manufacturing practices and quality assurance, regulatory authorities interfaces, communication and training, as well as marketing authorization procedures to ensure availability of radiopharmaceuticals. Finally domestic and regional supply to ensure patient access via alternative regulatory pathways, including in-house production of radiopharmaceuticals, is described and an outlook on regulatory challenges faced by new developments, such as the use of alpha emitters, is provided. All these considerations are an outcome of a dedicated Technical Meeting organized by the IAEA in 2023.

Keywords: Radiopharmaceutical; Regulations; Legislation; Regulatory framework; GMP; Marketing authorization

Permalink: https://www.hzdr.de/publications/Publ-37553


Establishment and Molecular Characterization of an In Vitro Model for PARPi-Resistant Ovarian Cancer.

Klotz, D. M.; Schwarz, F.; Dubrovska, A.; Schuster, K.; Theis, M.; Krüger, A.; Kutz, O.; Link, T.; Wimberger, P.; Drukewitz, S.; Buchholz, F.; Thomale, J.; Kuhlmann, J. D.

Abstract

Overcoming PARPi resistance is a high clinical priority. We established and characterized comparative in vitro models of acquired PARPi resistance, derived from either a BRCA1-proficient or BRCA1-deficient isogenic background by long-term exposure to olaparib. While parental cell lines already exhibited a certain level of intrinsic activity of multidrug resistance (MDR) proteins, resulting PARPi-resistant cells from both models further converted toward MDR. In both models, the PARPi-resistant phenotype was shaped by (i) cross-resistance to other PARPis (ii) impaired susceptibility toward the formation of DNA-platinum adducts upon exposure to cisplatin, which could be reverted by the drug efflux inhibitors verapamil or diphenhydramine, and (iii) reduced PARP-trapping activity. However, the signature and activity of ABC-transporter expression and the cross-resistance spectra to other chemotherapeutic drugs considerably diverged between the BRCA1-proficient vs. BRCA1-deficient models. Using dual-fluorescence co-culture experiments, we observed that PARPi-resistant cells had a competitive disadvantage over PARPi-sensitive cells in a drug-free medium. However, they rapidly gained clonal dominance under olaparib selection pressure, which could be mitigated by the MRP1 inhibitor MK-751. Conclusively, we present a well-characterized in vitro model, which could be instrumental in dissecting mechanisms of PARPi resistance from HR-proficient vs. HR-deficient background and in studying clonal dynamics of PARPi-resistant cells in response to experimental drugs, such as novel olaparib-sensitizers.

Keywords: PARPi resistance; cisplatin; ovarian cancer

Permalink: https://www.hzdr.de/publications/Publ-37552


Ion-induced telecom single photon emitters in silicon

Astakhov, G.; Hollenbach, M.; Klingner, N.; Jagtap, N.; Bischoff, L.; Fowley, C.; Kentsch, U.; Hlawacek, G.; Erbe, A.; Abrosimov, N. V.; Helm, M.; Berencen, Y.

Abstract

A review of single photon emitters in silicon based on ion-induced defects is provided. Fabrication methods and current state of the art are discussed.

Keywords: Telecom-wavelength single-photon sources; Color centers in silicon; Focused ion beam

Involved research facilities

Related publications

  • Invited lecture (Conferences)
    Workshop on Spin-Photon Interfaces for Quantum Communication, 01.09.2023, Vienna, Austria

Permalink: https://www.hzdr.de/publications/Publ-37551


Superstructure-dependent stability of DNA origami nanostructures in the presence of chaotropic denaturants

Hanke, M.; Dornbusch, D.; Tomm, E.; Grundmeier, G.; Fahmy, K.; Keller, A.

Abstract

The structural stability of DNA origami nanostructures in various chemical environments is an important factor in numerous applications, ranging from biomedicine and biophysics to analytical chemistry and materials synthesis. In this work, the stability of six different 2D and 3D DNA origami nanostructures is assessed in the presence of three different chatropic salts, i.e., guanidinium sulfate (Gdm2SO4), guanidinium chloride (GdmCl), and tetrapropylammonium chloride (TPACl), which are widely employed denaturants. Using atomic force microscopy (AFM) to quantify nanostructural integrity, Gdm2SO4 is found to be the weakest and TPACl the strongest DNA origami denaturant, respectively. Despite different mechanisms of actions of the selected salts, DNA origami stability in each environment is observed to depend on DNA origami superstructure. This is especially pronounced for 3D DNA origami nanostructures, where mechanically more flexible designs show higher stability in both GdmCl and TPACl than more rigid ones. This is particularly remarkable as this general dependence has previously been observed under Mg2+-free conditions and may provide the possibility to optimize DNA origami design toward maximum stability in diverse chemical environments. Finally, it is demonstrated that melting temperature measurements may overestimate the stability of certain DNA origami nanostructures in certain chemical environments, so that such investigations should always be complemented by microscopic assessments of nanostructure integrity.

Keywords: circular dichroism; AFM; DNA melting; ionic interactions; DNA hydration

Permalink: https://www.hzdr.de/publications/Publ-37550


Strategic wafer-scale creation of telecom single-photon emitters in silicon for large-scale quantum photonic integrated circuits

Berencen, Y.

Abstract

Indistinguishable single-photon sources at telecom wavelengths are the key photonic qubits for transmitting quantum information over long distances in standard optical fibers with minimal transmission losses and high fidelity. This enables secure quantum communication over the quantum internet and, in turn, a modular approach to quantum computing. The monolithic integration of single-photon sources with reconfigurable photonic elements and single-photon detectors in a silicon chip is a key enabling step toward demonstrating scalable quantum hardware such as quantum photonic integrated circuits (QPICs). Nowadays, nearly all the necessary components for QPICs are available such as superconducting single-photon detectors, low-loss photonic waveguides, delay lines, modulators, phase shifters, and low-latency electronics. Yet, the practical implementation of scalable quantum hardware has been largely hampered by the lack of on-chip single-photon emitters in silicon that can be created at desired locations on the nanoscale.
Here, we demonstrate two complementary wafer-scale protocols for the quasi-deterministic creation of single G and W telecom-wavelength color centers in silicon with a probability exceeding 50%. Both approaches are fully compatible with current silicon technology and enable the fabrication of single telecom quantum emitters at desired nanoscale positions on a silicon chip. These results unlock a clear and easily exploitable pathway for industrial-scale photonic quantum processors with technology nodes below 100 nm.

Keywords: Telecom-wavelength single-photon sources; Color centers in silicon; Focused ion beam

Involved research facilities

Related publications

  • Invited lecture (Conferences)
    2023 RAISIN – Roadmap for Applications of Implanted Single Impurities Network, 06.-08.09.2023, University of Surrey, Guildford, United Kingdom

Permalink: https://www.hzdr.de/publications/Publ-37549


HELPMI: HElmholtz Laser-Plasma Metadata Initiative

Bagnoud, V.; Bussmann, M.; Debus, A.; Hornung, J.; Kaluza, M.; Kessler, A.; Pöschel, F.; Schlenvoigt, H.-P.; Schramm, U.

Abstract

HELPMI is a 2-year project, subsidized by the Helmholtz Metadata Collaboration, conducted by GSI, HI Jena and HZDR (lead). The aim is to start the development of a F.A.I.R. data standard for experimental data of the entire laser-plasma (LPA) community. Such standard does not yet exist. It will facilitate management and analysis of usually quite heterogeneous experimental data and logs by rich and machine-actionable metadata, allowing automated processing of broad and long data sets. To date, the LPA community is widely using openPMD, an open meta-standard, well-established for simulations. NeXus is a similarly hierarchical and extensible standard for various experimental methods of the Photon and Neutron science community. Within HELPMI, we plan to adopt NeXus for LPA experimental data and simultaneously to make openPMD and its API extensible for custom hierarchies like NeXus. Thereby we can achieve interoperability of the standards, circumventing the need for another standard. Alongside we will start developing a glossary of LPA experimental terms in order to achieve re-usability. The glossary shall be community-driven and technically open, extensible and implementation-independent.

Keywords: data standard; metadata; data management

Involved research facilities

  • HIBEF
  • ATHENA
  • Draco
  • Penelope
  • Lecture (Conference)
    6th European Advanced Accelerator Concepts workshop, 18.-22.09.2023, La Biodola Bay, Isola d'Elba, Italy

Permalink: https://www.hzdr.de/publications/Publ-37547


Exploring the Potential of Nanogels: From Drug Carriers to Radiopharmaceutical Agents

Kubeil, M.; Suzuki, Y.; Casulli, M. A.; Kamal, R.; Hashimoto, T.; Bachmann, M.; Hayashita, T.; Stephan, H.

Abstract

Nanogels open up access to a wide range of applications and offer among others hopeful approaches for use in the field of biomedicine. This review provides a brief overview of current developments of nanogels in general, particularly in the fields of drug delivery, therapeutic applications, tissue engineering and sensor systems. Specifically, cyclodextrin (CD)-based nanogels are important because they have exceptional complexation properties and are highly biocompatible. Nanogels as a whole and CD-based nanogels in particular can be customized in a wide range of sizes and equipped with a desired surface charge as well as containing additional molecules inside and outside, such as dyes, solubility-mediating groups or even biological vector molecules for pharmaceutical targeting. Currently, biological investigations are mainly carried out in vitro, but more and more in vivo applications are gaining importance. Modern molecular imaging methods are increasingly being used for the latter. Due to an extremely high sensitivity and the possibility of obtaining quantitative data on pharmacokinetic and pharmacodynamic properties, nuclear methods such as single photon emission computed tomography (SPECT) and positron emission tomography (PET) using radiolabeled compounds are particularly suitable here. The use of radiolabeled nanogels for imaging, but also for therapy, is being discussed.

Keywords: nanogels; cyclodextrin; drug delivery; radiolabeling; molecular imaging; theranostics

Permalink: https://www.hzdr.de/publications/Publ-37546


Cavity-mediated thermal control of metal-to-insulator transition in 1T-TaS2

Jarc, G.; Mathengattil, S. Y.; Montanaro, A.; Giusti, F.; Rigoni, E. M.; Sergo, R.; Fassioli, F.; Winnerl, S.; Zilio, S. D.; Mihailovic, D.; Prelovšek, P.; Eckstein, M.; Fausti, D.

Abstract

Placing quantum materials into optical cavities can provide a unique platform to control
quantum cooperative properties of matter, in the regimes of both weak and strong light-matter coupling. Here we show the first experimental evidence of the reversible touchless control of a metal-to-insulator phase transition in the charge density wave material 1T-TaS2 embedded in a tunable THz optical cavity. The switch between conductive and insulating behavior, which is obtained by mechanically tuning the distance between the cavity mirrors and their alignment, is related to a significant renormalization of the sample temperature. This suggests a Purcell-like scenario in which the spectral profile of the cavity modifies the energy exchange between the material and the external electromagnetic field. Our findings uncover a new path to control the thermodynamics and macroscopic transport properties of quantum materials by engineering their electromagnetic environment.

Keywords: metal-to-insulator transition; strong light-matter coupling; terahertz Fabry-Pérot cavity; phase transition

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Permalink: https://www.hzdr.de/publications/Publ-37545


Strong transient magnetic fields induced by THz-driven plasmons in graphene disks

Han, J. W.; Sai, P.; But, D.; Uykur, E.; Winnerl, S.; Kumar, G.; Chin, M. L.; Myers-Ward, R. L.; Dejarld, M. T.; Daniels, K. M.; Murphy, T. E.; Knap, W.; Mittendorff, M.

Abstract

Strong circularly polarized excitation opens up the possibility to generate and control effective magnetic fields in solid state systems, e.g., via the optical inverse Faraday effect or the phonon inverse Faraday effect. While these effects rely on material properties that can be tailored only to a limited degree, plasmonic resonances can be fully controlled by choosing proper dimensions and carrier concentrations. Plasmon resonances provide new degrees of freedom that can be used to tune or enhance the light-induced magnetic field in engineered metamaterials. Here we employ graphene disks to demonstrate light-induced transient magnetic fields from a plasmonic circular current with extremely high efficiency. The effective magnetic field at the plasmon resonance frequency of the graphene disks (3.5 THz) is evidenced by a strong (~1°) ultrafast Faraday rotation (~ 20 ps). In accordance with reference measurements and simulations, we estimated the strength of the induced magnetic field to be on the order of 0.7 T under a moderate pump fluence of about 440 nJ cm-2.

Keywords: Transient magnetic fields; Faraday rotation; Graphene; Plasmonics

Involved research facilities

  • F-ELBE

Permalink: https://www.hzdr.de/publications/Publ-37544


Multilayer Metamaterials with Ferromagnetic Domains Separated by Antiferromagnetic Domain Walls

Salikhov, R.; Samad, F.; Schneider, S.; Pohl, D.; Rellinghaus, B.; Böhm, B.; Ehrler, R.; Lindner, J.; Kiselev, N. S.; Hellwig, O.

Abstract

Magnetic nano-objects possess great potential for more efficient data processing, storage, and neuromorphic-type applications. Using high perpendicular magnetic anisotropy synthetic antiferromagnets in the form of multilayer-based metamaterials, the antiferromagnetic interlayer exchange energy is purposefully reduced below the out-of-plane demagnetization energy, which controls magnetic domain formation. In this unusual magnetic energy regime, as demonstrated via macroscopic magnetometry and microscopic Lorentz transmission electron microscopy, it becomes possible to stabilize nanometer-scale stripe and bubble textures consisting of ferromagnetic out-of-plane domain cores separated by antiferromagnetic in-plane Bloch-type domain walls. This unique coexistence of mixed ferromagnetic/antiferromagnetic order on the nanometer scale opens so far unexplored perspectives in the architecture of magnetic domain landscapes as well as the design and functionality of individual magnetic textures, such as bubble domains with depth-wise alternating chirality.

Keywords: Magnetizm; Magnetic Domains; Synthetic antiferromagnets; Transmission electron microscopy; micromagnetic simulations

Permalink: https://www.hzdr.de/publications/Publ-37543


NMR Spectroscopy at the Institute of Resource Ecology

Kretzschmar, J.; Schmeide, K.; Brendler, V.; Stumpf, T.

Abstract

Our research aims at a better understanding of fundamental processes defining transport and accumulation of radiotoxic elements such as U, Np, Pu, Am, Cm, as well as Tc and Se. This requires knowledge of their mobility in the environment and of their (radio)ecological behavior. The results will help to develop biochemically and radiochemically founded risk assessment schemes, remediation procedures in areas affected by uranium mining, and help to assess the long-term safety of final disposal sites for nuclear waste in geologic formations.
Therefore, we apply solution- and solid-state NMR to various simple and complex systems. Occasionally, lanthanide ions, Ln(III), are used as non-radioactive, isoelectronic analogs for trivalent actinides, An(III). Radionuclide complexation by small molecules is studied for, e.g., citrate [1,2], glutathione (GSH/GSSG) [3,4], as well as 2-phosphonobutane-1,2,4,-tricarbox-ylate (PBTC) [5] and nitrilotriacetate (NTA) [6]. Selenium and (organo)borates were subject of NMR studies, too [7–9]. Comprehensive kinetic and thermodynamic studies were performed for water addition to PQQ, a redox cofactor in Ln(III)-dependent alcohol dehydrogenases [10]. Indicator molecules excreted from carrot cells or fungi upon treatment with uranium were identified also by NMR [11,12]. Furthermore, the bulk structure as well as the interaction of organics (e.g., gluconate, PBTC) and/or radionuclides with calcium (aluminate) silicate hydrate (C (A )S H) phases related to cementitious materials critical for nuclear waste disposal infrastructures were characterized by 13C, 31P, 27Al, and 29Si MAS NMR [13,14].

Literature:

[1] J. Kretzschmar et al., Chem. Commun. 2020, 56, 13133. [2] J. Kretzschmar et al., Inorg. Chem. 2021, 60, 7998. [3] J. Kretzschmar et al., Chem. Commun. 2018, 54, 8697. [4] J. Kretzschmar et al., Inorg. Chem. 2020, 59, 4244. [5] J. Kretzschmar et al., Molecules 2022, 27, 4067. [6] S. Friedrich et al., Molecules 2023, submitted. [7] J. Kretzschmar et al., Dalton Trans. 2015, 44, 10508. [8] J. Schott et al., Dalton Trans. 2014, 43, 11516. [9] J. Schott et al., Dalton Trans. 2015, 44, 11095. [10] N. Al Danaf et al., Phys. Chem. Chem. Phys., 2022, 24, 15397. [11] J. Jessat et al., J. Hazard. Mater. 2022, 439, 129520. [12] A. Wollenberg et al., J. Hazard. Mater. 2021, 411, 125068. [13] S. Dettmann et al., Front. Nucl. Eng. 2023, 2, 1124856. [14] K. Schmeide et al., in preparation.

Keywords: NMR spectroscopy; Aqueous solution; Molecular structure; Thermodynamics; Actinides; Lanthanides

  • Poster
    44th GDCh FGMR Annual Discussion Meeting 2023, 18.-21.09.2023, Konstanz, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37542


Data publication: Fractography of Neutron Irradiated RPV Steels – A Comparison of Shift in Reference Temperature and Net Hardening

Das, A.; Chekhonin, P.; Houska, M.; Obermeier, F.; Altstadt, E.

Abstract

The research data contains fractographic and fracture toughness data

Keywords: Fracture mechanics testing; Sub-sized specimen; Fractography; Reactor pressure vessel steels; Reference Temperature; Neutron-irradiation

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Permalink: https://www.hzdr.de/publications/Publ-37541


Data publication: (Radio)labeling of Micro-/Nanoplastics by In-diffusion

Stricker, A.; Hilpmann, S.; Mansel, A.; Franke, K.; Schymura, S.

Abstract

Daten zur Radiomarkierung von Mikroplastikpartikeln: Cu-Komplexierung; Cu-64 eindiffusion, Fluoreszenz-Markierung; HSP screening; Hydrophobizitäts Messungen; Elektronen-/Lichtmikroskopie; Quellversuche; Spektren.

Keywords: microplastics; radiolabeling; Hansen solubility parameters; In-Diffusion

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Permalink: https://www.hzdr.de/publications/Publ-37539


Towards decoupling the effects of kinetic and potential ion energies: Ion flux dependent structural properties of thin (V,Al)N films deposited by pulsed filtered cathodic arc

Unutulmazsoy, Y.; Kalanov, D.; Oh, K.; Karimi Aghda, S.; Gerlach, J. W.; Braun, N.; Munnik, F.; Lotnyk, A.; Schneider, J. M.; Anders, A.

Abstract

Pulsed filtered cathodic arc deposition involves formation of energetic multiply charged metal ions, which help to form dense, adherent, and macroparticle-free thin films. Ions possess not only significant kinetic energy, but also potential energy primarily due to their charge, which for cathodic arc plasmas is usually greater than one. While the effects of kinetic ion energy on the growing film are well investigated, the effects of the ions’ potential energy are less known. In the present work, we make a step towards decoupling the contributions of kinetic and potential energies of ions on thin film formation. The potential energy is changed by enhancing the ion charge states via using an external magnetic field at the plasma source. The kinetic energy is adjusted by biasing the arc source (“plasma bias”), which allows us to approximately compensate the differences in kinetic energy while the substrate and ion energy detector remain at ground. However, application of an external magnetic field also leads to an enhancement of the ion flux and hence the desired complete decoupling of the potential and kinetic energy effects will require further steps. Charge-state-resolved energy distribution functions of ions are measured at the substrate position for different arc source configurations, and thin films are deposited using exactly those configurations. Detailed characterization of the deposited thin films is performed to reveal the correlations of changes in structure with kinetic and potential energies of multiply charged ions. It is
observed that the cathode composition (Al:V ratio) strongly affects the formation of the thermodynamically stable wurtzite or the metastable cubic phase. The external magnetic field applied at the arc source is found to greatly alter the plasma and therefore to be the primary, easily accessible
“tuning knob” to enhance film crystallinity. The effect of “atomic scale heating” provided by the ions’ kinetic and potential energies on the film crystallinity is investigated, and the possibility to deposit crystalline (V,Al)N films without substrate heating is demonstrated. This study shows an approach towards
distinguishing the contributions stemming from kinetic and potential energies of ions on the film growth, however, further research is needed to assess and distinguish the additional effect of ion flux intensity (current).

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-37538


Fractography of Neutron Irradiated RPV Steels – A Comparison of Shift in Reference Temperature and Net Hardening

Das, A.; Chekhonin, P.; Houska, M.; Obermeier, F.; Altstadt, E.

Abstract

Reactor pressure vessel (RPV) steels in nuclear reactors face embrittlement due to neutron irradiation. The embrittlement is associated with an increase in the reference temperature obtained via fracture toughness testing using the Master Curve concept. However, the fracture surfaces of some highly embrittled RPV steels exhibit ductile dimples. Through this work, we show that material properties, such as yield strength as a function of temperature, play an important role in determining the net hardening of a material. Additionally, we recorded the location of fracture initiators, using scanning electron microscopy (SEM) on the fracture surfaces of tested mini-C(T) specimens from four different RPV steels, to check whether it was affected by neutron irradiation and side grooving. We detected fracture initiators associated with high fracture toughness at greater distances to the crack tip. The locations of the fracture initiators changed significantly for samples with and without side-grooves and did not change significantly with respect to the irradiation state. We found the primary causes for increased ductility of embrittled RPV steels to be lower irradiation induced hardening and a higher loss in yield strength with increasing temperatures. Caution must therefore be exercised while interpreting the embrittlement of a material using ductile fracture surfaces alone.

Keywords: Fracture mechanics testing; Sub-sized specimen; Fractography; Reactor pressure vessel steels; Reference Temperature; Neutron-irradiation

Related publications

  • Lecture (Conference)
    Pressure Vessels & Piping Conference PVP2023, 19.07.2023, Atlanta, USA
  • Contribution to proceedings
    Pressure Vessels & Piping Conference PVP2023, 19.07.2023, Atlanta, USA
    Proceedings of the ASME 2023, Pressure Vessels and Piping Conference, 978-0-7918-8744-8
    DOI: 10.1115/PVP2023-103648

Permalink: https://www.hzdr.de/publications/Publ-37537


Evidence of free-bound transitions in warm dense matter

Dornheim, T.

Abstract

Warm dense matter (WDM) is now routinely created and probed in laboratories around the world, providing unprecedented insights into conditions achieved in stellar atmospheres, planetary interiors, and inertial confinement fusion experiments. However, the interpretation of these experiments is often filtered through models with systematic errors that are difficult to quantify. Due to the simultaneous presence of quantum degeneracy and thermal excitation, processes in which free electrons are de-excited into thermally unoccupied bound states transferring momentum and energy to a scattered x-ray photon become viable [1]. Here we show that such free-bound transitions are a particular feature of WDM and vanish in the limits of cold and hot temperatures. The inclusion of these processes into the analysis of recent X-ray Thomson Scattering experiments on WDM at the National Ignition Facility [2] and the Linac Coherent Light Source [3] significantly improves model fits, indicating that free-bound transitions have been observed without previously being identified. This interpretation is corroborated by agreement with a recently developed model-free thermometry technique [4,5] and presents an important step for precisely characterizing and understanding the complex WDM state of matter.

[1] M. Böhme et al, arXiv:2306.17653
[2] T. Döppner et al, Nature 618, 270-275 (2023)
[3] D. Kraus et al, PPCF 61, 014015 (2019)
[4] T. Dornheim et al, Nature Commun 13, 7911 (2022)
[5] T. Dornheim et al, POP 30, 042707 (2023)

  • Lecture (Conference)
    11th Workshop on High Pressure, Planetary and Plasma Physics (11HP4), 25.-27.09.2023, Rostock, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37536


3-D shape and velocity measurement of argon gas bubbles rising in liquid sodium by means of ultrafast X-ray CT imaging

Bieberle, M.; Gundrum, T.; Räbiger, D.; Bieberle, A.; Eckert, S.

Abstract

We present an evaluation study on the characterization of bubbles rising in liquid sodium by applying two-plane ultrafast X-ray computed tomography (UFXCT). It includes a new method for determining the three-dimensional shape and velocity vector of each individual bubble. In the experimental part, argon gas was injected through a single nozzle located slightly above the bottom of a cylindrical vessel filled with liquid sodium. The gas flow rate was varied between 10 and 635 cm3/min to obtain a chain of individual bubbles. In this parameter range, collisions of bubbles, coalescence or breakup are not expected. Measurements were carried out in a wide spatial range starting near the nozzle up to a height of about 200 mm above it. It was convincingly demonstrated that two-plane UFXCT imaging, in combination with the data processing presented here, allows a reliable characterization of the size, shape and velocity of bubbles with a size of a few millimeters in a sodium column of 54 mm diameter. Observed experimental results include a reproducible fluctuation of shape, position and velocity in the lower part of the column as well as lower terminal rise velocities compared to bubble chains in water.

Keywords: argon; liquid sodium; gas-liquid two-phase flow; ultrafast X-ray computed tomography; bubble charact

Involved research facilities

  • TOPFLOW Facility

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  • Secondary publication expected from 02.12.2024

Permalink: https://www.hzdr.de/publications/Publ-37535


Understanding warm dense matter: from ab initio simulations to experiments

Dornheim, T.

Abstract

The study of matter at extreme densities, temperatures, and pressures has emerged as a highly active frontier at the interface of a variety of disciplines including physics, material science, and quantum chemistry. Such warm dense matter (WDM) naturally occurs in astrophysical objects like giant planet interiors and brown dwarfs. Moreover, it is of key relevance for technological applications such as inertial confinement fusion and material synthesis. A particular feature of WDM is the complex interplay of effects such as Coulomb coupling and quantum degeneracy rendering its rigorous theoretical description a formidable challenge. Here I present an overview of a number of recent developments that bridge the gap between state-of-the-art simulation methods and WDM experiments [1,2]. These new methodologies have already been successfully applied to inelastic x-ray scattering experiments at the European XFEL and the National Ignition Facility [3,4], and open up a variety of exciting possibilities for future research at HIBEF.

[1] T. Dornheim et al, Nature Commun. 13, 7911 (2022)
[2] T. Dornheim et al, Phys. Plasmas 30, 032705 (2023)
[3] T. Dornheim et al, arXiv:2305.15305 (submitted)
[4] M. Böhme et al, arXiv:2306.17653 (submitted)

  • Poster
    The fourth workshop on Science of the Program “From Matter to Materials and Life” (MML), 27.-29.09.2023, Jena, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37534


High-field phase diagram of the chiral-lattice antiferromagnet Sr(TiO)Cu4(PO4)4

Nomura, T.; Kato, Y.; Motome, Y.; Miyake, A.; Tokunaga, M.; Kohama, Y.; Zherlitsyn, S.; Wosnitza, J.; Kimura, S.; Katsuyoshi, T.; Kimura, T.; Kimura, K.

Abstract

We studied the high-field phase diagram of a chiral-lattice antiferromagnet Sr(TiO)Cu4PO4)4 by means of ultrasound, dielectric, and magnetocaloric-effect measurements. These experimental techniques reveal two new phase transitions at high fields, which have not been resolved by previous magnetization experiments. Specifically, the c66 acoustic mode shows drastic changes with hysteresis for magnetic fields applied along the c axis, indicating a strong magnetoelastic coupling. Combined with cluster mean-field theory, we discuss the origin of these phase transitions. By considering the chiral-twist effect of Cu4O12 cupola units, which is inherent to the chiral crystal structure, the phase diagram is reasonably reproduced. The agreement between experiment and theory suggests that this material is a unique quasi-two-dimensional spin system with competing exchange interactions and chirality, leading to a rich phase diagram.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

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Permalink: https://www.hzdr.de/publications/Publ-37533


Numerical simulation of flashing flows in a converging-diverging nozzle with interfacial area transport equation

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

Abstract

Flashing flows of initially sub-cooled water in a converging–diverging nozzle is investigated numerically in the framework of the two-fluid model (TFM). The thermal non-equilibrium effect of phase change is considered by an interfacial heat transfer model, while the pressure jump across the interface is ignored. The bubble size distribution induced by nucleation, bubble growth/shrinkage, coalescence, and breakup is described based on the interfacial area transport equation (IATE) and constant bubble number density model (CBND), respectively. The results are compared with the experimental data. Satisfactory prediction of the axial pressure distribution along the nozzle as well as the flashing inception, is achieved by the TFM-IATE coupling method. It was also found that the vapor production in the diverging section was overpredicted, and the radial gas volume fraction distribution deviated from the experiment. The radial diameter profiles exhibit opposite patterns at the nozzle throat and near the outlet, and similar trends can be observed for the superheated degree. A poly-disperse method is suggested to be introduced to describe the evolution of interfacial area concentration.

Keywords: flashing flow; interfacial area concentration; interfacial area transport equation (IATE); two-fluid model (TFM)

Permalink: https://www.hzdr.de/publications/Publ-37532


Clinical urine microscopy for urinary tract infections

Liou, N.; De, T.; Urbanski, A.; Khasriya, R.; Yakimovich, A.; Horsley, H.

Abstract

Urinary tract infections (UTI) are a common disorder. Its diagnosis can be made by microscopic examination of voided urine for cellular markers of infection. We present a dataset containing 300 images and 3,562 manually annotated urinary cells labelled into seven classes of clinically significant urinary content. It is an enriched dataset with samples acquired from the unstained and untreated urine of patients with symptomatic UTI. The aim of the dataset is to facilitate UTI diagnosis in nearly all clinical settings by using a simple imaging system which leverages advanced machine learning techniques. 

Data acquisition 

300 urine samples were obtained from patients with symptomatic UTI between April and August 2022 from a specialist LUTS outpatient clinic in central London. Urine samples were collected as natural voids and processed on-site within one hour to mitigate cellular degradation. Brightfield microscopic examination (Olympus BX41F microscope frame, U-5RE quintuple nosepiece, U-LS30 LED illuminator, U-AC Abbe condenser) was performed at x20 objective (Olympus PLCN20x Plan C N Achromat 20x/0.4). A disposable haemocytometer (C Chip™) was used for enumeration of red cells (RBC), white cells (WBC), epithelial cells (EPC), and the presence of other cellular content per 1 µl of urine by two experienced microscopists.

Images were acquired using the aforementioned brightfield microscope using a 0.5X C-mount adapter connected to a digital colour camera (Infinity 3S-1UR, Teledyne Lumenera). Images were taken in 16-bit colour in 1392 x 1040 .tif format using Capture and Analyse software. An enriched dataset approach was taken to maximise urinary cellular content in the acquired images. Such data curation was also necessary to overcome class imbalance. Daily Kohler illumination and global white balance was performed to ensure consistency in image acquisition. 

Dataset annotation

300 images were acquired and manually annotated by first identifying cells of interest as a binary semantic segmentation task. Individual pixels were dichotomously labelled as either informative cells, foreground, or non-informative background. Non-informative background was further constrained by including unidentifiable cells, such as debris or grossly out-of-focus particles. Binary annotation was initially performed using ilastik, an open-source software using a Random Forest classifier for pixel classification, then manually refined at the pixel level to ensure accurate semantic segmentation. This produced a binary mask in 1392 x 1040 .tif format for each corresponding raw colour image. 

Objects of interest were then manually labelled by two expert microscopists into one of seven clinically significant multi-class categories: rods, RBC/WBC, yeast, miscellaneous, single EPC, small EPC sheet, and large EPC sheet. This produced a multi-class mask in 1392 x 1040 .tif format with a label as pixel value from 0-7, where 0 is background (Table 1). 

Data structure 

The dataset is organised into three root folders: img (image), bin_mask (binary mask), and mult_mask (multi-class mask). Each folder has 300 files in .tif format and labelled with an incremental number.

Table1

Folder         Files        Objects               Count       Pixel Values

img              300        Raw data                                 0-255
bin_mask         300        Background/Foreground                      0/1
mult_mask        300        Background/Class                             0
                            Rod                    1697                  1
                            RBC/WBC                1056                  2
                            Yeast                    41                  3
                            Miscellaneous           550                  4
                            Single EPC              182                  5
                            Small EPC sheet          26                  6
                            Large EPC sheet          10                  7
                                
                            Total                  3562         

Keywords: clinical microscopy; urine microscopy; widefield; transmission light; image segmentation; binary segmentation; multiclass segmentation

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Permalink: https://www.hzdr.de/publications/Publ-37531


Effects of geometry and topology in curvilinear ferro- and antiferromagnets

Makarov, D.

Abstract

The behaviour of any physical system is determined by the order parameter whose distribution is governed by the geometry of the physical space of the object, in particular its dimensionality and curvature [1]. Curvilinear magnetism is a framework, which helps understanding the impact of geometrical curvature on complex magnetic responses of curved 1D wires and 2D shells [2-4]. The lack of inversion symmetry and emergence of curvature induced anisotropy and Dzyaloshinskii-Moriya interaction (DMI) stemming from the exchange interaction [5,6] are characteristic of curved surfaces. Recently, a non-local chiral symmetry breaking was discovered [7], which is responsible for the coexistence and coupling of multiple magnetochiral properties within the same magnetic object [8]. Regarding antiferromagnets, it is demonstrated that intrinsically achiral one-dimensional curvilinear antiferromagnets behave as a chiral helimagnet with geometrically tunable DMI, orientation of the Neel vector and the helimagnetic phase transition [9-11]. This positions curvilinear antiferromagnets as a platform for geometrically tunable antiferromagnetic spinorbitronics.

[1] P. Gentile et al., “Electronic materials with nanoscale curved geometries”. Nature Electronics (review) 5, 551 (2022).
[2] D. Makarov et al., “Curvilinear micromagnetism: from fundamentals to applications” (Springer, Zurich, 2022).
[3] D. Makarov et al., “New dimension in magnetism and superconductivity: 3D and curvilinear nanoarchitectures”. Adv. Mat. (review) 34, 2101758 (2022).
[4] D. Sheka et al., “Fundamentals of curvilinear ferromagnetism: statics and dynamics of geometrically curved wires and narrow ribbons”. Small (review) 18, 2105219 (2022).
[5] Y. Gaididei et al., “Curvature effects in thin magnetic shells”. Phys. Rev. Lett. 112, 257203 (2014).
[6] O. Volkov et al., “Experimental observation of exchange-driven chiral effects in curvilinear magnetism”. Phys. Rev. Lett. 123, 077201 (2019).
[7] D. Sheka et al., “Nonlocal chiral symmetry breaking in curvilinear magnetic shells”. Commun. Phys. 3, 128 (2020).
[8] O. Volkov et al., “Chirality coupling in topological magnetic textures with multiple magnetochiral parameters”. Nature Com. 14, 1491 (2023).
[9] O. Pylypovskyi et al., “Curvilinear one-dimensional antiferromagnets”. Nano Lett. 20, 8157 (2020).
[10] O. Pylypovskyi et al., “Curvature-driven homogeneous Dzyaloshinskii-Moriya interaction and emergent weak ferromagnetism in anisotropic antiferromagnetic spin chains”. Appl. Phys. Lett. 118, 182405 (2021).
[11] Y. Borysenko et al., “Field-induced spin reorientation transitions in antiferromagnetic ring-shaped spin chains”. Phys. Rev. B 106, 174426 (2022).

Keywords: curvilinear magnetism; 3D nanostructures

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  • Invited lecture (Conferences)
    seminar at the QuSpin Center for Quantum Spintronics, 20.-23.09.2023, Trondheim, Norway

Permalink: https://www.hzdr.de/publications/Publ-37530


Advanced fabrication

Makarov, D.

Abstract

In this lecture for magnetism students, we cover different fabrication methods to produce bulk, thin film, composites, 3D magnetic functional samples.

Keywords: crystal growth; thin films; 2D materials; magnetic composites

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  • Invited lecture (Conferences)
    2023 European School on Magnetism, 04.-15.09.2023, Madrid, Spain

Permalink: https://www.hzdr.de/publications/Publ-37529


Multifunctional nanostructures

Makarov, D.

Abstract

In this lecture for magnetism students we review different magnetic materials with focus on their functionality and related application directions. Bulk, thin films, 2D materials, heterostructures, 3D magnetic architectures are addressed in the lecture.

Keywords: nanomagnetism; 3D nanostructures; printed magnetoelectronics

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  • Invited lecture (Conferences)
    2023 European School on Magnetism, 04.-15.09.2023, Madrid, Spain

Permalink: https://www.hzdr.de/publications/Publ-37528


Influence of structural Fe content in clay minerals on selenite redox reactions: Kinetics and structural transformations

Qian, Y.; Scheinost, A.; Grangeon, S.; Hoving, A.; Churakov, S. V.; Marques Fernandes, M.

Abstract

Selenium immobilization is of high importance due to its high toxicity and the mobility of the soluble oxyanion selenite. Fe-bearing clay minerals are major redox-active ingredients of Earth’s critical zone and constitute an important component of the barrier in (radioactive and other) waste repositories, having the potential to reduce selenite to insoluble forms under anaerobic condition. Our research focuses on a systematical investigation of the kinetics of selenite sorption and reduction, considering variations in structural Fe(II) content of clay minerals, redox potential and pH. Combining batch experiments and X-ray absorption fine structure (XAFS) spectroscopy, we examine how these factors influence the selenite reduction process and kinetics by identifying the reduced Se species over time. We observed that selenite adsorption and reduction are kinetically controlled. Selenite reduction is redox potential dependent and presents a slower reduction rate at pH 7 compared to pH 5. Concerning Fe(II) content in clay minerals, higher amount of structural Fe(II) results in faster selenite reduction kinetics, and only elemental Se(0) was observed as reduced species, while the absence of soluble Fe prevented precipitation of Fe selenide. Moreover, we observed a transformation of amorphous red Se(0) to metallic trigonal grey Se(0) in the reduction species as the reaction time increases. This insight into the selenite reduction mechanism provides valuable information for the development of effective approaches for selenite immobilization.

Keywords: Selenium; Clay; ROBL; EXAFS; XANES; Redox

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Permalink: https://www.hzdr.de/publications/Publ-37527


Huge magnetostriction in superconducting single-crystalline BaFe1.908Ni0.092As2

Zhang, M.; Wu, J.; Shi, K.; Ling, L.; Tong, W.; Xi, C.; Pi, L.; Wosnitza, J.; Luo, H.; Wang, Z.

Abstract

The performance of iron-based superconductors in high magnetic fields plays an important role for their practical application. In this work, we measured the magnetostriction and magnetization of BaFe1.908Ni0.092As2 single crystals using pulsed magnetic fields up to 60 T and static magnetic fields up to 33 T, respectively. A huge longitudinal magnetostriction (of the order of 10–4) was observed in the direction of twin boundaries. The magnetization measurements evidence a high critical-current density due to strong bulk pinning. By using magnetization data with an exponential flux-pinning model, we can reproduce the magnetostriction curves qualitatively. This result shows that the magnetostriction of BaFe1.908Ni0.092As2 can be well explained by a flux-pinning-induced mechanism.

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  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-37526


Ein modulares Leistungsrechnungsprogramm für konventionelle und hybrid-elektrische Flugantriebe

Condriuc, I.; Krüger, T.; Wiegand, M.; Schuchard, L.; Mailach, R.

Abstract

Die Reduktion klimaschädlicher Emissionen ist ein wesentliches Ziel im modernen Luftverkehr. Dafür geeignete Ansätze
stellen unter anderem emissionsoptimierte Flugprofile sowie der Einsatz von hybrid-elektrischen Antriebstechnologien
dar. Um die damit verbundenen Potentiale zügig identifizieren und quantifizieren zu können, werden performante
0D-Triebwerksmodelle benötigt, die die Leistungsrechnung thermischer und hybrid-elektrischer Flugantriebe im Auslegungspunkt
und im Off-Design abbilden.
Die vorliegende Arbeit stellt ein solches Modell für Leistungsrechnung, Emissions- und Massenabschätzung vor. Dabei
liegt ein besonderer Fokus auf einem flexiblen, modularen Aufbau, sodass das Framework um neue Architekturen
und zusätzliche (bspw. elektrische) Komponenten erweitert werden kann. Bereits hinterlegt sind etablierte ein- und
mehrwellige thermische Turbojet-, Turbofan- und Turboprop-Architekturen sowie verschiedene (hybrid-)elektrische
Konfigurationen. Gegenüber einer etablierten kommerziellen Referenz (GasTurb) ergeben sich für die Leistungsgrößen
dort verfügbarer Architekturen Abweichungen deutlich kleiner als ein Prozent, die typischerweise durch die
Genauigkeit der verfügbaren Stoffwerte limitiert werden. Das Triebwerksdesign kann in einem Auslegungspunkt
definiert und quasi-stationär im Off-Design berechnet werden, wobei die entlang einer Flugmission entstehenden
Schubanforderungen mittels der Bibliothek OpenAP vorgegeben werden können. An dieser Stelle schlägt sich die
Abschätzung des Systemgewichts, welches durch die jeweilige Architektur und ihre Komponenten erheblich beeinflusst
wird, besonders nieder. Dies wird bspw. hinsichtlich des Treibstoffverbrauchs anhand eines ausgewählter Missionsprofils
demonstriert. Für die Massen- und Emissionsabschätzung wird auf eine Datenbank bestehender Maschinen
zurückgegriffen.
Die aktuelle und zukünftige Entwicklung des Modells konzentriert sich auf eine weiter verbesserte Massenabschätzung,
alternative Kraftstoffe und weitere Triebwerksarchitekturen, insbesondere mit Wärmeübertragern, die dank des
modularen Aufbaus leicht eingebunden werden können. Damit ermöglicht dieses Leistungsrechnungsprogramm eine
noch schnellere und umfangreichere Vorhersage von thermodynamischen Größen entlang des Gaspfades, Effizienz,
Emissionen und Massen für die erfolgreiche Evaluation neuer Triebwerksdesigns und Missionsprofile.

Keywords: Triebwerks-Leistungsrechnung; hybrid-elektrische Flugantriebe; Massen- und Emissionsabschätzung

  • Open Access Logo Contribution to proceedings
    Deutschen Luft- und Raumfahrtkongress (DLRK) 2023, 19.-21.09.2023, Stuttgart, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-37525


Droplet-based microfluidics as bioreactors for bacterial community study and patient postoperative monitoring

Zhao, X.; de Visser, A. G. M.; Kolbinger, F. R.; Bachmann, M.; Baraban, L.

Abstract

Droplet-based microfluidics that emerged a decade ago has offered a new route to boost the efficiency of biochemical methods in terms of detection time and sensitivity [Kaminski et al., Chem. Soc. Rev. 46, 2017]. Droplet-based fluidic technology saves materials consumption and reduces experimental wastes, allowing for real-time and individual tracking of each reactor, and has found numerous applications in biology and biotechnology [Baraban et al., Lab. Chip, 11, 2011]. In our lab, we developed a droplet-based microfluidic system to detect the bioreaction (e.g., bacterial growth, antibiotic effect, enzyme reaction dynamic, and so on) in high throughput and sensitivity by detecting fluorescence signals. The system achieves monitoring the bioreaction in the hundred to thousand droplets with the size of 200 nL with multi-channel automatically. Depending on the different purposes, this system can be adjusted to monitor the same batch of analytes over time in the long term (days), or continuously real-time detect analytes level change, as well as to switch between various optical settings.
For example, we used the millifluidic droplets reactor system to study the bacterial coexistence by monitoring two Escherichia coli strains' growth simultaneously in real time [Zhao et al., Lab. Chip, 21, 2021]. Our system offers an environment with high statistical output, unaffected bacteria growth, and long-time measurements in a well-mixed liquid inhabit. By reading fluorescence in two parallel detector channels, we obtained and analyzed the monoculture and co-culture of these two strains E. coli BFP and E. coli YFP and explained the interaction and relationship between them. In another work, we investigated the antibiotic effect on bacterial coexistence. Our automatic nanoliter droplet analyzer is used to study the interactions of the sensitive and resistant strains of E. coli in the presence of antibiotics and to define the criteria leading to the emergence of cross-protection phenomena.
Moreover, due to the quick response and high sensitivity properties, we miniaturized the system to a bedside portable size and introduced it to the clinical field of real-time sensing drain α-amylase activity for postoperative monitoring of patients undergoing pancreatic surgery. Based on the reaction of the starch-FL reagent with amylase to produce a fluorescence intensity that correlates with the concentration of amylase, thus enabling the detection of the patient's amylase level. In this work, our strategy significantly improves the determination time (3 min) and detection limit (7 nmol/s·L) and reduces material requirement (10 μL) and wastes.
In the future, we expect to apply our portable device in more clinical scenarios, e.g., lactate and lipase level monitoring, and septicemia determination, in which case bacteria poisons the blood, and needs urgent and accurate low-concentration detection. Not limited to aqueous phase droplets, our research group also focused on solid and semi-solid environments, such as incubating bacteria or cancer cells in gel beads or capsules. For instance, we encapsulated two bacterial strains in agarose gel beads to study the effect of space on bacterial coexistence [Nguyen Le et al., Micromachines, 14, 2023]. We also cultured cancer cells in capsules and adjusted the core-shell ratio to structure cell growth conditions [Peng et al., Biotechnology Journal, 2023].

Keywords: Droplet-based microfluidics; Optical biosensor; Bacterial coexistence; Postoperative monitoring; Amylase level detection

  • Invited lecture (Conferences)
    29th International Symposium on Electro- and Liquid-Phase Separation Techniques, 13.-17.09.2023, Rome – San Felice Circeo, Italy

Permalink: https://www.hzdr.de/publications/Publ-37524


First principles GW-Bethe Salpeter equation excitonic spectrum of van der Waals heterostructure: The case of PtS2-SnS2 heterostructure

Karthikeyan, C.; Sudheer, A. E.; Devaraj, M.; Posselt, M.

Abstract

The accurate determination of light absorption in the material is necessary to understand the photocatalytic mechanism. Here, we present the systematic study of light absorption in the prototypical Van derWaals (vdW) heterostructure PtS2-SnS2 by including the electron-hole interaction in the computational calculation by the GW Bethe Salpeter Equation (GW-BSE) approach. The GGA-PBE level bandgap of the PtS2 -SnS2 vdW heterostructure is calculated to be 1.09 eV which is less than that of monolayers of PtS2 and SnS2. Later, GW-BSE absorption spectra pointed out the bound excitonic peaks of PtS2-SnS2 vdW heterostructure which have significant impact on the light absorption property of the material. The first excitonic peak of this vdW heterostructure obtained at the 2.17 eV which is in the low energy range compared to monolayers of PtS2 and SnS2. This low energy shift of the first excitonic peak will be favourable for better light absorption as well as boosted photoconversion efficiency of the PtS2-SnS2 vdW heterostructure.

Keywords: DFT; GW-BSE; VdW heterostructure; 2D materials; excitons; photocatalysis

  • Poster
    PHOTONICS 2023, 05.-08.07.2023, Bengaluru, India

Permalink: https://www.hzdr.de/publications/Publ-37523


Accurate determination of excitonic spectra of monolayer Selenium - PtS2 van der Waals heterostructure

Sudheer, A. E.; Devaraj, M.; Posselt, M.

Abstract

The newly discovered monolayer selenium from group VI elements gains prominence due to its potential application in diverse fields including optoelectronics. In this work we have performed a systematic first principles study on the structural, electronic, linear and nonlinear optical characteristics of selenium Van der Waals (vdW) heterostructure with noble metal chalcogenide PtS2. The GW-Bethe-Salpeter Equation (GW-BSE) approach was used to accurately treat the quasiparticle and excitonic spectra. The optimized heterostructure shows the indirect band gap of 0.82 eV at GGA-PBE level. The newly designed interface shows type II band alignment. GW-BSE absorption spectra show a bound excitonic peak at 1.40 eV as compared with 1.28 eV in monolayer Se. The exciton binding energy of the Se-PtS2 vdW interface is 0.35 eV compared with the 0.45 eV for monolayer Se. The strong excitonic visible light absorption together with the type II band alignment makes the Se-PtS2 vdW heterostucture suitable candidate for the photovoltaic and photocatalytic applications.

Keywords: DFT; GW-BSE; 2D materials; Type II band alignment; exciton binding energy

  • Lecture (Conference)
    PHOTONICS 2023, 05.-08.07.2023, Bengaluru, India

Permalink: https://www.hzdr.de/publications/Publ-37522


Challenges of Electron Correlation Microscopy on Amorphous Silicon and Amorphous Germanium

Radic, D.; Peterlechner, M.; Spangenberg, K.; Posselt, M.; Bracht, H.

Abstract

Electron correlation microscopy experiments were conducted on amorphous germanium (a-Ge) and amorphous silicon (a-Si) with the goal to study self-diffusion. For this purpose, a series of tilted dark-field images were acquired during in situ heating of the samples in a transmission electron microscope. These experiments show that the measurements are greatly affected by artefacts. Contamination, crystallization, electron beam-induced sputtering, and macroscopic bending of the samples pose major obstacles to the measurements. Other, more subtle experimental artefacts could occur in addition to these which makes interpretations regarding the structural dynamics nearly impossible. The data were nonetheless evaluated to see if some useful information could be extracted. One such result is that the distribution of the characteristic times τ(KWW⁠), which were obtained from stretched exponential fits to the intensity autocorrelation data, is spatially heterogeneous. This spatial heterogeneity is assumed to be caused by a potential nonergodicity of the materials, the artefacts or an inhomogeneous amorphous structure. Further data processing shows that the characteristic times τ(KWW) are moreover temperature independent, especially for the a-Ge data. It is concluded that the structural rearrangements over time are primarily electron beam-driven and that diffusive dynamics are too slow to be measured at the chosen, experimentally accessible annealing temperatures.

Keywords: Electron correlation microscopy; structural dynamics; amorphous germanium; amorphous silicon

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  • Secondary publication expected from 26.08.2024

Permalink: https://www.hzdr.de/publications/Publ-37521


Novel Metalless Chalcogen-Based Janus Layers: A Density Functional Theory Study

Vallinayagam, M.; Sudheer, A. E.; Aravindh, A. S.; Devaraj, M.; Nadarajan, R.; Katta, R.; Posselt, M.; Zschornak, M.

Abstract

The electronic, thermodynamic, and optical properties of a new type of twodimensional Janus layer (JL) consisting exclusively of chalcogens are investigated using first principles calculations. The permutations on atomic sites provide increased stability due to the multi-valency of chalcogens, and a heavier central atom further stabilizes the layer due to the increased coordination number. The investigated JLs are indirect bandgap materials with a bandgap larger than 1.23 eV, making them suitable for photocatalytic activity. Different feasible chemical potentials are analyzed, and chalcogens’ poor limits are proposed to fabricate the JLs. Based on the comparison of the formation energy, the energetic profile of the JLs is identified as Ef(TeSeS) < Ef(SSeTe) < Ef(SeSTe), irrespective of the chemical potentials of chalcogen. Hence, TeSeS is more stable than the JL arrangements SSeTe and SeSTe. The flat bands around the Fermi energy level and the reduction in path length between the maximum of conduction and minimum of valence bands explain the magnitude of multiple peaks observed in the optical spectra of the JLs. These absorptions turn the studied JLs into potential candidates for water splitting. The optimized bandgap reveals that the band edges efficiently straddle the water redox potentials at different pH levels. In addition, the positive vibrational frequencies depict the stability of these layers. Because of the minimal formation energy requirement, higher density of states around the Fermi level, as well as enhanced optical absorption compared to other JL, TeSeS JLs may lead to enhanced performance in photovoltaic and photocatalytic applications. These results add new members to the JL family of pure chalcogens and pave the way toward novel materials for respective applications.

Keywords: Chalcogen-based 2D materials; Metalless Janus layers; First-principles study

Permalink: https://www.hzdr.de/publications/Publ-37520


Control of Four-Magnon Scattering by Pure Spin Current in a Magnonic Waveguide

Hache, T.; Körber, L.; Hula, T.; Lenz, K.; Kakay, A.; Hellwig, O.; Lindner, J.; Faßbender, J.; Schultheiß, H.

Abstract

We use a pure spin current originating from the spin Hall effect to generate a spin-orbit torque strongly reducing the effective damping in an adjacent ferromagnet. Because of additional microwave excitation, large spin-wave amplitudes are achieved exceeding the threshold for four-magnon scattering, thus resulting in additional spin-wave signals at discrete frequencies. Two or more modes are generated below and above the directly pumped mode with equal frequency spacing. It is shown how this nonlinear process can be controlled in magnonic waveguides by the applied dc current and the microwave pumping power. The sudden onset of the nonlinear effect after exceeding the thresholds can be interpreted as a spiking phenomenon, which makes the effect potentially interesting for neuromorphic computing applications. Moreover, we investigated this effect under microwave frequency and external field variation. The appearance of the additional modes was investigated in the time domain, revealing a time delay between the directly excited and the simultaneously generated nonlinear modes. Furthermore, spatially resolved measurements show different spatial decay lengths of the directly pumped mode and nonlinear modes.

Keywords: spin waves; magnetism; BLS; four-magnon scattering; spin current; spintronics; magnonics

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Permalink: https://www.hzdr.de/publications/Publ-37519


An improved correlation for the estimation of the yield strength from small punch testing

Altstadt, E.

Abstract

This study aims at improving the empirical correlation for estimating the yield strength from small punch tests. The currently used procedure in the European standard EN 10371 to determine the elastic-plastic transition force – based on bi-linear fitting – involves a dependency not only on the onset of plastic flow but also on the work hardening of the material. Consequently, the yield strength correlation factor is not universal but depends on the material properties and on the ge-ometry of the small punch set-up – leading to a significant uncertainty in the yield strength estima-tion. In this study, an alternative definition of the elastic-plastic transition force is proposed, which significantly less depends on the work hardening of the material and on the small punch geome-try. The approach is based on extensive elastic-plastic finite element simulations with generic ma-terial properties, including a systematic variation of the yield strength, ultimate tensile strength, and uniform elongation. The new definition of the transition force is based on the deviation of the force-deflection curve from the analytical elastic slope derived by Reissner's plate theory. A signifi-cant reduction of the uncertainty of the yield strength estimation is demonstrated.

Keywords: small punch test; yield strength; empirical correlation; finite element simulation; plate theory

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Permalink: https://www.hzdr.de/publications/Publ-37517


Proton penetration mechanism and selective hydrogen isotope separation through two-dimensional biphenylene

Jiahui, Z.; Changti, P.; Yue, Z.; Xiyu, L.; Guozhen, Z.; Yang, L.

Abstract

Hydrogen isotope separation is of prime significance in various scientific and industrial applications. Nevertheless, the existing technologies are often expensive and energy demanding. Two-dimensional carbon materials are regarded as promising candidates for cost-effective separation of different hydrogen isotopes. Herein, based on theoretical calculations, we have systematically investigated proton penetration mechanism and the associated isotope separation behavior through two-dimensional biphenylene, a novel graphene allotrope. The unique non-uniform rings with different sizes in biphenylene layer resemble the topological defects of graphene, serving as proton transmission channels. We found that proton can readily pass through biphenylene with low energy barrier in some specific patterns. Furthermore, large kinetic isotope effect ratios for proton-deuteron (13.58) and proton-triton (53.10) were observed in aqueous environment. We thus conclude that biphenylene would be a potential carbon material used for hydrogen isotope separation. This subtle exploitation of the natural structural specificity of biphenylene casts new insight into the search of materials for hydrogen isotope separation.

Keywords: Proton penetration; Hydrogen isotope separation; Two-dimensional biphenylene

Permalink: https://www.hzdr.de/publications/Publ-37516


Towards automated prompt-gamma treatment verification: Feasibility of PGI simulations on cone-beam CTs

Bertschi, S.; Stützer, K.; Berthold, J.; Pietsch, J.; Korreman, S.; Elstrøm, U.; Vestergaard, A.; Smeets, J.; Janssens, G.; Richter, C.

Abstract

Cone-beam CTs are a promising solution for fast imaging required by Online Adaptive Proton Therapy. Verifying adapted treatment plans with prompt-gamma-imaging (PGI) requires a reference simulation on the respective planning image. Cone-beam CTs and conventional fan-beam CTs were acquired for a homogeneous PMMA cylinder and an antropomorphic head phantom. Two RayStation algorithms were used to create a corrected cone-beam CT and a virtual CT for each phantom. PGI simulations were performed on all datasets and compared to a corresponding dose evaluation. CBCT data was shown to be suitable for PGI reference simulations if range prediction is correct, which is a requirement for plan adaptation. Uncertainty in material assignment due to noise in CBCT does not worsen PGI emission signal.

Involved research facilities

  • OncoRay
  • Poster
    RAPTOR school und 4D workshop, 09.-15.09.2023, Villigen, Schweiz

Permalink: https://www.hzdr.de/publications/Publ-37515


Investigation of Complex Electrical Properties of Concrete during Decommissioning of Nuclear Power Plants: An Experimental Analysis

Nurjahan, T.; Schleicher, E.; de Assis Dias, F.; Hampel, U.

Abstract

Electrical impedance spectroscopy (EIS) is a powerful technique for characterizing the electrical properties of materials and systems. EIS involves the measurement of complex impedance and can provide valuable insight into inhomogeneous cementitious materials, including the sensitivity to moisture content. Therefore, this work contributes to the determination of moisture content (MC) in concrete composites. A comprehensive study of the complex electrical properties of concrete was performed experimentally in a frequency range between 10 Hz and 10 MHz implementing impedance spectroscopy.

Keywords: Electrical impedance spectroscopy; complex electrical properties; concrete; moisture

Involved research facilities

  • TOPFLOW Facility
  • Contribution to proceedings
    16th International Workshop on Impedance Spectroscopy, 26.-29.09.2023, Chemnitz, Germany
    IEEE: IEEE, 56-60
    DOI: 10.1109/IWIS61214.2023.10302749

Permalink: https://www.hzdr.de/publications/Publ-37514


Spatiotemporal Studies of Soluble Inorganic Nanostructures with X-rays and Neutrons

Yin, J.-F.; Amidani, L.; Chen, J.; Li, M.; Xue, B.; Lai, Y.; Kvashnina, K.; Nyman, M.; Yin, P.

Abstract

This review addresses the use of X-ray and neutron scattering and X-ray absorption to describe how inorganic nano-structured materials assemble, evolve, and function in solution. We first provide an overview of techniques and instrumentation (both large user facilities and benchtop). We review recent studies of soluble inorganic nanostructure assembly, covering the disciplines of materials synthesis, processes in nature, nuclear materials, and the widely applicable fundamental processes of hydrophobic interactions and ion-pairing. Reviewed studies cover size regimes and length scales ranging from sub-angstrom (coordination chemistry and ion-pairing) to several nanometers (molecular clusters; i.e. polyoxometalates, polyoxocations and metal-organic polyhedra), to meso-scale (supramolecular assembly processes). Reviewed studies predominantly exploit 1) SAXS/SWAXS/SANS (small and wide angle X-ray or neutron scattering), 2) PDF (pair distribution function analysis of X-ray total scattering), and 3) XANES and EXAFS (respectively X-ray absorption near edge structure and extended X-ray absorption fine structure). While the scattering techniques provide structural information, X-ray absorption yields oxidation state, in addition to local coordination. Our goal for this review is to provide information and inspiration for the inorganic/materials science communities that may benefit from elucidating the role of solution speciation in natural and synthetic processes.

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  • Secondary publication expected from 25.09.2024

Permalink: https://www.hzdr.de/publications/Publ-37513


Defects distribution and evolution in selected-area helium ion implanted 4H-SiC

Song, Y.; Xu, Z.; Rommel, M.; Astakhov, G.; Hlawacek, G.; Fang, F.

Abstract

Color centers in silicon carbide has been widely studied in view of the promising near-infrared emission near the low-loss telecom wavelengths as well as the maturity of semiconductor technology of silicon carbide material. Recently, there is an urgent need to generate color centers in predetermined location so as to integrate with photonic cavities of waveguides. In this paper, we report an experimentally demonstration of the generation of VSi, CSiVC, and NCVSi color centers in 4H-SiC using helium ion microscope in 5×5 µm areas with subsequent annealing treatment. Combined with transmission electron microscopy (TEM), photoluminescence (PL) and cathodoluminescence (CL) spectroscopy and Raman stress analysis, the evolution and distribution of color centers were thoroughly investigated. Cross-sectional TEM revealed the presence of helium bubbles in center of the implanted region with high doses which account for the observed quench of PL emission in center of the implanted regions in both PL and CL measurements. PL spectra from the virgin, implanted and annealed samples proved the appearance of VSi after implantation and the transformation from VSi to CSiVC and NCVSi centers after annealing at 1000 ℃. Moreover, as the increase of the implantation dose, the area of NCVSi centers increases whereas that of CSiVC decreases, which implied a competitive relationship between the formation of CSiVC and NCVSi defects. The comparison between stress distribution and CSiVC defect distribution illustrated that CSiVC centers predominantly distributed around the surface rupture region after thermal annealing where significant stress repair occurred. The results suggest that focused helium ion implantation holds promise for the precise coupling of VSi, CSiVC and NCVSi centers in predefined location in integrated photonics applications.

Keywords: Silicon carbide; color center; defects; ion implantation; photoluminescence; Raman; Stress; cathodoluminescence

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Permalink: https://www.hzdr.de/publications/Publ-37512


Data publication: Mass density vs. energy density at cosmological scales

Eingorn, M.; Yilmaz, E.; Yukselci, A. E.; Zhuk, O.

Abstract

The dataset consists of matter power spectra at four redshifts (z=80,50,15,0) generated by simulating Lambda-Cold Dark Matter cosmology with respect to two distinct weak-field expansion schemes (one relevant to the energy density and the other relevant to the mass density of matter) as described in the associated paper. Additionally, it contains the power spectrum of the gravitational potential at the same redshift values, based on the expansion scheme of the screening approach only.

Keywords: N-body simulations; large-scale structure; inhomogeneous Universe; cosmological perturbations; power spectrum; cosmic screening

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Permalink: https://www.hzdr.de/publications/Publ-37511


Mass density vs. energy density at cosmological scales

Eingorn, M.; Yilmaz, E.; Yukselci, A. E.; Zhuk, O.

Abstract

In the presence of the gravitational field, the energy density of matter no longer coincides with its mass density. A discrepancy exists, of course, also between the associated power spectra. Within the ΛCDM model, we derive a formula that relates the power spectrum of the energy density to that of the mass density and test it with the help of N-body simulations run in comoving boxes of 2.816 Gpc/h. The results confirm the validity of the derived formula and simultaneously show that the power spectra diverge significantly from one another at large cosmological scales.

Keywords: N-body simulations; large-scale structure; inhomogeneous Universe; cosmological perturbations; power spectrum; cosmic screening

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Permalink: https://www.hzdr.de/publications/Publ-37510


A multimodal X-ray spectroscopy investigation of uranium speciation in ThTi2O6 compounds with the brannerite structure

Dixon Wilkins, M. C.; Townsend, L. T.; Stennett, M. C.; Kvashnina, K.; Corkhill, C. L.; Hyatt, N. C.

Abstract

ThTi2O6 derived compounds with the brannerite structure were designed, synthesised, and characterised with the aim of stabilising incorporation of U5+ or U6+, at dilute concentration. Appropriate charge compensation was targeted by co-substitution of Gd3+, Ca2+, Al3+, or Cr3+, on the Th or Ti site. U L3 edge X-ray Absorption Near Edge Spectroscopy (XANES) and High Energy Resolution Fluorescence Detected U M4 edge XANES evidenced U5+ as the major oxidation state in all compounds, with a minor fraction of U6+ (2–13%). The balance of X-ray and Raman spectroscopy data support uranate, rather than uranyl, as the dominant U6+ speciation in the reported brannerites. It is considered that the U6+ concentration was limited by unfavourable electrostatic repulsion arising from substitution in the octahedral Th or Ti sites, which share two or three edges, respectively, with neighbouring polyhedra in the brannerite structure.

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Permalink: https://www.hzdr.de/publications/Publ-37509


Technetium-99 Reduction in Carbonate Environment: An Spectroelectrochemical and ⁹⁹Tc-NMR Study

Bureika, A.; Kretzschmar, J.; Mayordomo, N.

Abstract

Technetium-99 (⁹⁹Tc) is a radioactive isotope with a long half-live (211,000 a). It is produced in nuclear power plants and nuclear weapon detonation since it is a fission product of U-235 and Pu-239. In addition, 99Tc forms after gamma ray emission of metastable technetium-99 (99mTc), which is the most used isotope for cancer diagnosis at hospitals [1]. The emission of ⁹⁹Tc in the environment is hazardous for living organisms and depends on its chemical speci-ation, being especially decisive the oxidation state. Thus, several works focused on the speciation (e.g., [2–4]) and immobilization of Tc (e.g., [5,6]) based on redox changes.
The nuclear properties of Tc99 make it suitable to study Tc molecular structures by NMR [7,8] and, depending on the oxidation state and thus electron configuration, also by EPR [9] spec-troscopies. Despite the power of both these methods, they have been rarely used for envi-ronmental studies.
In this work we reduced KTcO₄ electrochemically in carbonate solutions in dependence on pH (8.2–10.0), Tc concentration (0.5–9.5 mM), carbonate concentration (5–1000 mM), and the applied potential. Tc(VII) reduction was monitored in the UV-vis range in situ using a spec-tro-electrochemical cell. At -0.85 V a pink solution (λmax 512 nm) was obtained, corresponding to a Tc(IV) carbonate species [2], whereas reduction at -0.95 V yields a bluish green solution (λmax 630 nm), associated with a Tc(III) carbonate complex [2]. The obtained solutions were then investigated by ⁹⁹Tc NMR. The −0.85 V solution reveals a resonance at ~1600 ppm, indicative of a carbonate species of Tc(V) since the chemical shift range is characteristic for Tc in +V oxidation state [7]. The other specimen yielded at −0.95 V, in addition to the former Tc(V) signal at about 1600 ppm, gives rise to one additional signal at ~152 ppm, which is in the chemical shift range expected for Tc(III) [7].
These are unprecedented NMR data on aqueous Tc carbonate species, which advance the mechanistic understanding of Tc redox behavior and help to improve safety and risk analyses for nuclear waste management.
Literature:
[1] A.H. Meena et al., Env. Chem Lett. 2017, 15, 241.
[2] J. Paquette et al., Can. J. Chem. 1985, 63, 2369.
[3] M. Chotkowski et al., J. Electroanal. Chem. 2018, 814, 83.
[4] D.M. Rodríguez et al, Inorg. Chem. 2022, 61, 10159.
[5] N. Mayordomo et al., Chem. Eng. J. 2021, 408, 127265.
[6] C.I. Pearce et al., Sci. Total Environ. 2020, 716, 132849.
[7] V.A. Mikhalev, Radiochemistry 2005, 47, 319.
[8] G.B. Hall et al., Inorg. Chem. 2016, 55, 8341.
[9] U. Abram et al., Radiochim. Acta. 1993, 63, 139.

Keywords: Technetium; Electrochemistry; Carbonate; Nuclear magnetic resonance; Electroreduction

  • Poster
    FGMR Annual Discussion Meeting 2023, 18.-21.09.2023, Konstanz, Germany

Permalink: https://www.hzdr.de/publications/Publ-37508


Dataset for: A novel, scenario-based approach to comparing non-pharmaceutical intervention strategies across nations

Calabrese, J.; Schüler, L.; Fu, X.; Gawel, E.; Zozmann, H.; Bumberger, J.; Quaas, M.; Wolf, G.; Attinger, S.

Abstract

This dataset includes all data discussed in the publication "A novel, scenario-based approach to comparing non-pharmaceutical intervention strategies across nations".

Keywords: COVID-19; NPI; modelling; epidemiological; behavioural; macroeconomic

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Permalink: https://www.hzdr.de/publications/Publ-37507


Dynamic behavior of grain boundaries with misorientations in the vicinity of Σ3 coherent and incoherent twin boundaries in Al bicrystals.

Brandenburg, J.-E.; Barrales-Mora, L. A.; Tsurekawa, S.; Molodov, D. A.

Abstract

The migration behaviour of different grain boundaries with misorientations close to the Σ3 CSL orientation relationship in
high purity Al bicrystals under the capillary driving force and applied mechanical stress was investigated. The experiments
were performed by an in-situ technique to observe and measure the boundary migration with a scanning electron
microscope. The ability of the nearly Σ3 60°〈111〉 incoherent {110} and {112} boundaries to move under capillary driving
force was found to depend critically on the initial boundary inclination. While boundaries with inclinations near {112} can
easily assume a curved shape and migrate, boundaries with an initial {110} plane remain stationary or form non-mobile
facets. This is attributed to the essential anisotropy of the inclination dependence of the energy γ(ψ) of 60°〈111〉 tilt
boundaries with differently high torque dγ/dψ around {112} and {110} inclinations, as revealed by atomistic simulations of the
respective boundaries. The Σ3 70.5°〈110〉 tilt boundary with the geometry corresponding to the coherent {111} twin
boundary, was found to be immobile under both driving forces applied. The 59.2° 〈111〉 tilt grain boundary with geometry
near the Σ3 {110} incoherent twin boundary was found to be quite mobile under applied shear stress. The measured
migration activation enthalpy H = 0.45 eV for this boundary is the lowest among the values obtained in previous experiments
for any other stress driven grain boundary in Al bicrystals of the same purity. Moreover, this boundary migrated with a zero
coupling factor, i.e. without producing any measurable shear parallel to the boundary plane.

Keywords: Bicrystal; Boundary energy; Grain boundary migration; Inclination; Stress; Scanning electron microscopy

Permalink: https://www.hzdr.de/publications/Publ-37504


Radiation damage evolution in High Entropy Alloys (HEAs) caused by 3-5 MeV Au and 5 MeV Cu ions in a broad range of dpa in connection to mechanical properties and internal morphology

Mackova, A.; Havránek, V.; Mikšová, R.; Fernandes, S.; Matejicek, J.; Hadraba, H.; Vilemova, M.; Liedke, M. O.; Martan, J.; Vronka, M.; Haušild, P.; Butterling, M.; Honnerova, P.; Elsherif, A. G. A.; Wagner, A.; Lukac, F.

Abstract

High Entropy Alloys (HEAs) are prospective materials for nuclear fusion reactors and were irradiated in this study at a broad range of energetic ion fluences. Different ion masses (Cu and Au ions) and energies (3 and 5 MeV) were selected to investigate dpa (displacement per atom) development, radiation defect accumulation based on prevailing collision processes (Au ions) and ionization processes (Cu ions) in various HEAs. The studied HEAs differ in terms of elemental composition, internal morphology (grain structure) and other modifiers. Dpa values of 1 to ~66 were achieved at Cu and Au ion fluences from 4e14 to 1.3e16 ions.cm-2 at room temperature, which generated varying levels of lattice damage. Theoretical simulations were performed to estimate the energy stopping and dpa depth distribution using SRIM code and compared with Au-concentration depth profiles determined by Rutherford backscattering
spectrometry for Au-ions with 3MeV ion energy. The prevailing energy losses of ions via ionization processes for Cu-5MeV ions were found to increase the damage through lattice strain and probable lattice distortion, although the main defect introduction is expected to occur via collisions during nuclear stopping. Structural modification and defect accumulation were investigated by positron annihilation spectroscopy (PAS), which revealed a broader damaged layer with defects, where HEA-Nb (NbCrFeMnNi) exhibited the least damage accumulation from chosen alloys with no strong relation to the Au-5MeV ion implantation fluence, whereas strong defect accumulation was recorded in the Au-ion implanted Eurofer97 used for comparison and HEA-Co (CoCrFeMnNi). PAS analysis also allowed defect sizes to be determined as an additional structural characteristic. The observed trends were also confirmed by thermal property analysis, with a worsening of thermal effusivity recorded after the irradiation in HEA-Co and Eurofer97. The worsening of the thermal properties was confirmed by the layer thickness, where the layer identified by PAS was found to be broader than the SRIM theoretical predictions. Nanoindentation measurements confirmed less pronounced radiation hardening of HEA-Nb relative to that observed in HEA-Co and Eurofer97. Transmission Electron Microscopy (TEM) analysis revealed layer thicknesses in reasonable agreement with the dpa depth profiles. The thermal effusivity decreased in the surfaceirradiated layer in all investigated samples, the least influenced material was HEA-Nb.

Keywords: high entropy alloys; ion irradiation; positron annihilation spectroscopy; radiation damage; defects; CoCrFeMnNi; NbCrFeMnNi

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Permalink: https://www.hzdr.de/publications/Publ-37503


Status of Advanced Photocathodes for SRF Guns

Xiang, R.

Abstract

As well known, the quality of the photocathodes is critical for the stability and reliability of photo-injector operation. Especially for the superconducting rf guns, the photocathode is one of the most important parts. In last years, thanks to the developed photocathode technology, several SRF guns were successfully operated or tested for the beam generation at kHz-MHz repetition rate. In this review, the achievements as well as open questions for the cathode requirements of the reliable SRF gun operation will be reviewed, and the possible improvement from photocathodes point of view for the future application will be discussed.

Keywords: photocathode; SRF guns

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  • Lecture (Conference)
    67th ICFA Advanced beam Dynamics Workshop on Future Light Sources: FLS2023, 27.08.-01.09.2023, Luzern, Switzerland

Permalink: https://www.hzdr.de/publications/Publ-37502


A critical review of the solution chemistry, solubility, and thermodynamics of europium: recent advances on the Eu(III) hydrolysis

Jordan, N.; Thoenen, T.; Spahiu, K.; Kelling, J.; Starke, S.; Brendler, V.

Abstract

This review is aiming at providing a critical assessment of the published complexation constants and solubility products related to the hydrolysis of Eu(III) in aqueous medium. Original experimental data available from peer-reviewed scientific publications were the main source for the selection of thermodynamic data, together with technical reports and Eu(III)-data-containing thermodynamic databases starting from around 1900 until July 2023. The methodology followed by the Thermochemical Database Project of the Nuclear Energy Agency, which uses the Specific ion Interaction Theory (SIT) for describing activity coefficients in aqueous electrolyte solutions, was strictly applied, with a few minor deviations, however. The selected and rejected literature data were thoroughly discussed as well as the procedures enabling the derivation of recommended complexation constants, solubility products, thermodynamic functions at infinite dilution (1 bar, 25 °C), together with ion interaction coefficients ε(j;k). These recommended data complement our former study on the chloride, sulphate, and phosphate ligands and will further contribute to the establishment of a comprehensive, internally consistent, and reliable thermodynamic reference database for the chemical, geochemical, and chemotechnical modeling of europium.

Keywords: Europium; thermodynamic database; complexation constant; solubility product; hydrolysis; SIT

Permalink: https://www.hzdr.de/publications/Publ-37501


Toward using collective x-ray Thomson scattering to study C–H demixing and hydrogen metallization in warm dense matter conditions

Ranjan, D.; Ramakrishna, K.; Voigt, K.; Humphries, O. S.; Heuser, B.; Stevenson, M. G.; Lütgert, B. J.; He, Z.; Qu, C.; Schumacher, S.; May, P. T.; Amouretti, A.; Appel, K.; Brambrink, E.; Cerantola, V.; Chekrygina, D.; Fletcher, L. B.; Göde, S.; Harmand, M.; Hartley, N.; Hau-Riege, S. P.; Makita, M.; Pelka, A.; Schuster, A.; Smid, M.; Toncian, T.; Zhang, M.; Preston, T. R.; Zastrau, U.; Vorberger, J.; Kraus, D.

Abstract

The insulator–metal transition in liquid hydrogen is an important phenomenon to understand the interiors of gas giants, such as Jupiter and Saturn, as well as the physical and chemical behavior of materials at high pressures and temperatures. Here, the path toward an experimental approach is detailed based on spectrally resolved x-ray scattering, tailored to observe and characterize hydrogen metallization in dynamically compressed hydrocarbons in the regime of carbon–hydrogen phase separation. With the help of time-dependent density functional theory calculations and scattering spectra from undriven carbon samples collected at the European x-ray Free-Electron Laser Facility (EuXFEL), we demonstrate sufficient data quality for observing C–H demixing and investigating the presence of liquid metallic hydrogen in future experiments using the reprated drive laser systems at EuXFEL.

Keywords: Time dependent density functional theory; Metallization process; Thomson scattering; X-ray scattering; Free electron lasers; High energy density physics

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  • HIBEF

Permalink: https://www.hzdr.de/publications/Publ-37500


Stability and speciation of hydrated magnetite {111} surfaces from ab initio simulations with relevance for geochemical redox processes

Katheras, A. S.; Karalis, K.; Krack, M.; Scheinost, A.; Churakov, S. V.

Abstract

Magnetite is a common mixed Fe(II,III) iron oxide in mineral deposits and the product of (anaerobic) iron corrosion. In various Earth systems, magnetite surfaces
participate in surface mediated redox reactions. The reactivity and redox properties of the magnetite surface depend on the surface speciation, which varies with the environmental conditions. In this study, Kohn-Sham density functional theory (DFT+U method) was used to examine the stability and speciation of the magnetite crystal face
{111} in a wide range of pH and Eh conditions. The simulations reveal that oxidation state and speciation of the surface depend strongly on imposed redox conditions and,
in general, differ from those of the bulk state. Corresponding predominance phase diagrams for the surface speciation and structure were calculated from first principles.
1The obtained knowledge of surface structure and oxidation state of iron is essential for modeling retention of redox-sensitive nuclides. Further, classical molecular dynamics
(MD) simulations were conducted investigating the mobility of water near the magnetite surface.

Keywords: Magnetite; DFT; Redox; ROBL

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  • Secondary publication expected from 22.12.2024

Permalink: https://www.hzdr.de/publications/Publ-37499


The Past, Present, and Future of the Brain Imaging Data Structure (BIDS)

Poldrack, R. A.; Markiewicz, C. J.; Appelhoff, S.; Ashar, Y. K.; Auer, T.; Baillet, S.; Bansal, S.; Beltrachini, L.; Bertazzoli, G.; Bhogawar, S.; Blair, R. W.; Bortoletto, M.; Boudreau, M.; Brooks, T. L.; Bénar, C. G.; Calhoun, V. D.; Castelli, F. M.; Clement, P.; Cohen, A. L.; Cohen-Adad, J.; Dambrosio, S.; Delorme, A.; Devinsky, O.; Draschkow, D.; Duff, E. P.; Dupre, E.; Earl, E.; Esteban, O.; Feingold, F. W.; Flandin, G.; Galassi, A.; Gallitto, G.; Ganz, M.; Gholam, J.; Ghosh, S. S.; Giacomel, A.; Gillman, A. G.; Gleeson, P.; Gramfort, A.; Guay, S.; Guidali, G.; Halchenko, Y. O.; Handwerker, D. A.; Hardcastle, N.; Herholz, P.; Hermes, D.; Honey, C. J.; Innis, R. B.; Ioanas, H.-I.; Jahn, A.; Karakuzu, A.; Keator, D. B.; Kiar, G.; Kincses, B.; Laird, A. R.; Lau, J. C.; Lazari, A.; Legarreta, J. H.; Li, A.; Li, X.; Love, B. C.; Lu, H.; Maumet, C.; Mazzamuto, G.; Meisler, S. L.; Mikkelsen, M.; Mutsaerts, H.; Nichols, T. E.; Nikolaidis, A.; Nilsonne, G.; Niso, G.; Norgaard, M.; Okell, T. W.; Oostenveld, R.; Ort, E.; Park, P. J.; Pawlik, M.; Pernet, C. R.; Pestilli, F.; Petr, J.; Phillips, C.; Poline, J.-B.; Pollonini, L.; Raamana, P. R.; Ritter, P.; Rizzo, G.; Robbins, K. A.; Rockhill, A. P.; Rogers, C.; Rokem, A.; Rorden, C.; Routier, A.; Saborit-Torres, J. M.; Salo, T.; Schirner, M.; Smith, R. E.; Spisak, T.; Sprenger, J.; Swann, N. C.; Szinte, M.; Takerkart, S.; Thirion, B.; Thomas, A. G.; Torabian, S.; Varoquaux, G.; Vaya, M. D. L. I.; Voytek, B.; Welzel, J.; Wilson, M.; de Hollander, G.; de la Vega, A.; Gorgolewski, K. J.

Abstract

The Brain Imaging Data Structure (BIDS) is a community-driven standard for the organization of data and metadata from a growing range of neuroscience modalities. This paper is meant as a
history of how the standard has developed and grown over time. We outline the principles behind the project, and the mechanisms by which it has been extended. We also discuss the lessons learned through the project, with the aim of enabling researchers in other domains to learn from the success of BIDS.

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  • PET-Center

Permalink: https://www.hzdr.de/publications/Publ-37498


Data publication: Metallic Nanowires Self-Assembled in quasi-circular Nanomolds Templated by DNA Origami

Ruiz Arce, D. D.; Jazavandi Ghamsari, S.; Erbe, A.; Samano, E. C.

Abstract

IV-measurements of nanowires discussed in the paper 

Keywords: DNA nanotechnology; nanoelectronics; self-assembly; nanomaterials

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Permalink: https://www.hzdr.de/publications/Publ-37497


A Quasi-2D Polypyrrole Film with Band-Like Transport Behavior And High Charge Carrier Mobility

Liu, K.; Réhault, J.; Liang, B.; Hambsch, M.; Zhang, Y.; Seçkin, S.; Zhou, Y.; Shivhare, R.; Zhang, P.; Polozij, M.; König, T. A. F.; Qi, H.; Zhou, S.; Fery, A.; Mannsfeld, S. C. B.; Kaiser, U.; Heine, T.; Banerji, N.; Dong, R.; Feng, X.

Abstract

Quasi-2D (q2D) conjugated polymers (CPs) are polymers that consist of linear CP chains assembled through non-covalent interactions to form a layered structure. In this work, the synthesis of a novel crystalline q2D polypyrrole (q2DPPy) film at the air/H2SO4 (95%) interface is reported. The unique interfacial environment facilitates chain extension, prevents disorder, and results in a crystalline, layered assembly of protonated quinoidal chains with a fully extended conformation in its crystalline domains. This unique structure features highly delocalized π-electron systems within the extended chains, which is responsible for the low effective mass and narrow electronic bandgap. Thus, the temperature-dependent charge-transport properties of q2DPPy are investigated using the van der Pauw (vdP) method and terahertz time-domain spectroscopy (THz-TDS). The vdP method reveals that the q2DPPy film exhibits a semiconducting behavior with a thermally activated hopping mechanism in long-range transport between the electrodes. Conversely, THz-TDS reveals a band-like transport, indicating intrinsic charge transport up to a record short-range high THz mobility of ≈107.1 cm2*V^{−1}*s^{−1}.

Permalink: https://www.hzdr.de/publications/Publ-37496


Europa braucht Schlagkraft auf den Rohstoffmärkten; Handelsblatt 223/2021

Gutzmer, J.; Kullik, J.

Abstract

Die EU ist bei Rohstoffen für Energiewende und Digitalisierung vom Ausland abhängig. Eine EU-Rohstoffagentur soll das ändern, fordern Jakob Kullik und Jens Gutzmer.

Keywords: Rohstoffe; EU; Energiewende; Rohstoffagentur

  • Communication & Media Relations
    Handelsblatt 17.11.2021
    1 Seiten

Permalink: https://www.hzdr.de/publications/Publ-37494


Photoluminescence Properties of Lanthanide-Doped Alumina and YAG Aerogels

Metzkow, N.; Klemmed, B.; Georgi, M.; Hübner, R.; Eychmüller, A.

Abstract

In this work, the range of alumina (Al2O3) and yttrium aluminum garnet (YAG) aerogels was extended by doping them with lanthanide ions. The aerogels were synthesized by using a universal, epoxide-assisted sol−gel method. They were thermally treated to induce structural changes, which were characterized in more detail by using X-ray diffraction and electron microscopy. The alumina samples showed topotactic phase transformations from boehmite, via γ-alumina to a mixed alumina phase, while the YAG started as an amorphous mixed oxide phase, which crystallized at 1000 °C into pure crystalline YAG. In order to expand the functionalities of the aerogels, they were doped with the rare-earth ions Eu3+ and Tb3+ (3 mol %). The red or green photoluminescence could be observed only starting from a temperature treatment of 550 °C, which can be related to the defect reduction and crystallinity increase due to phase transformations and sintering processes occurring. For the first time, the photoluminescence quantum yields of luminescent aerogels could be determined. The highest quantum yield of 25.5 ± 1.1 % was achieved for the Al2O3-Tb-1000 sample.

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Permalink: https://www.hzdr.de/publications/Publ-37493


Wenn der Roboter-Hund auf Spurensuche geht - Ein Rückblick auf die Lange Nacht der Wissenschaft und Wirtschaft am Helmholtz-Institut Freiberg für Ressourcentechnologie; Acamonta 2022

Jentzsch, A.-K.

Abstract

Die Lange Nacht der Wissenschaft und Wirtschaft ist seit 2007 eine Institution in Freiberg und begeistert alle zwei Jahre Groß und Klein bei spannenden Experimenten, Vorträgen und Führungen. Das Virus ließ die Neugierigen nun noch ein Jahr länger warten, aber am 18. Juni war es endlich so weit. Über 1.000 Besucher zog es ans Helmholtz-Institut Freiberg für Ressourcentechnologie (HIF), um hautnah zu erleben, womit sich die Forschenden an einem Institut des Helmholtz-Zentrums Dresden-Rossendorf (HZDR) so beschäftigen. Zahlreiche Experimente, Mitmach-Aktionen und Führungen begeisterten die Wissenschaftsinteressierten trotz der sommerlich heißen Temperaturen.

Keywords: Lange Nacht; Freiberg; Tag der offenen Tür

  • Acamonta - Zeitschrift für Freunde und Förderer der TU Bergakademie Freiberg 29(2022)1, 116-117

Permalink: https://www.hzdr.de/publications/Publ-37492


Experimental investigation of microparticle erosion in shear flows

Lecrivain, G.

Abstract

From microplastics to pollen grains resuspending into the atmosphere, the resuspension of microparticles by a turbulent gas flow occurs in many natural, environmental and industrial systems. A subtle interplay between drag, lift and adhesion forces occur during the particle detachment. In this lecture, the role of turbulence and wall roughness on particle deposition and resuspension will be explained. I will also showcase how can one measure aerosol deposition and resuspension in opaque and complex geometries.

Keywords: Particle resuspension; Turbulent flows; Lecture

  • Invited lecture (Conferences)
    9th Gerhard Jirka Summer School "Sediment Dynamics in Open Waters – Measurements Modelling Applications“,, 28.08.-01.09.2023, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-37491


Data publication: In-bulk temperature profile mapping using Fiber Bragg Grating in fluids

Su, S.; Niu, T.; Vogt, T.; Eckert, S.

Abstract

Raw data from - optical fiber FBG, acquired with FiSens software - thermocouple data, qcauired with custom Labview

Keywords: optical fiber; fiber Bragg Grating (FBG); temperature sensor; in-bulk measurement; multiplexing; temperature mapping

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Permalink: https://www.hzdr.de/publications/Publ-37490


Data publication, PET: Development of the High-Affinity Carborane-Based Cannabinoid Receptor Type 2 PET Ligand [18F]LUZ5-d8

Gündel, D.

Abstract

DICOM dataset of dynamic PET aquisitions and images associated with the publication: Development of the High-Affinity Carborane-Based Cannabinoid Receptor Type 2 PET Ligand [18F]LUZ5-d8 (DOI: 10.1021/acs.jmedchem.3c00195), funded by DFG (MO 2677/4-1).

Keywords: cannabinoid receptor; ligand; protein binding; animal; brain; diagnostic imaging; metabolism; positron emission tomography; procedures; rat; Animals; Brain; Ligands; Positron-Emission Tomography; Protein Binding; Rats; Receptors; Cannabinoid

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Permalink: https://www.hzdr.de/publications/Publ-37489


Cadmium sorption on alumina nanoparticles, and mixtures of alumina and smectite: An experimental and modelling study

Mayordomo, N.; Missana, T.; Alonso, U.

Abstract

Cadmium (Cd) is one of the most toxic transition metals for living organisms. Thus, effective measures to remediate Cd from water and soils need to be developed. Cd immobilization by alumina, and mixtures of alumina and smectite have been analyzed experimentally and theoret-ically by sorption experiments and sorption modelling, respectively. Cd aqueous removal was dependent on pH and Cd concentration, being maximum for pH>7.5. A two-site non-electrostatic sorption model for Cd sorption on alumina was developed and it successfully reproduced the experimental Cd immobilization on alumina. Cd sorption on mixtures of alumina and smectite depended on pH, ionic strength, and alumina content in the mixture. Cd removal in mixtures increased when alumina content increased at high pH and ionic strength values. On the contrary, Cd sorption decreased when alumina content increased under acidic conditions and low ionic strength due to the dissolution of alumina and the release of Al³⁺ into the suspension. Cd sorp-tion model on mixtures of alumina and smectite was reproduced by considering the individual Cd sorption models for alumina and smectite. The model of Cd sorption on mixtures was addi-tive when the competition of Al³⁺ with Cd²⁺ for cation exchange in smectite was included.

Keywords: Cd; sorption model; retention; immobilization; heavy metals; Al2O3

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Permalink: https://www.hzdr.de/publications/Publ-37488


β1 integrin mediates unresponsiveness to PI3Kα inhibition for radiochemosensitization of 3D HNSCC models

Korovina, I.; Elser, M.; Borodins, O.; Seifert, M.; Willers, H.; Cordes, N.

Abstract

Phosphoinositide 3-kinase (PI3K)-α represents a key intracellular signal transducer involved in the regulation of key cell functions such as cell survival and proliferation. Excessive activation of PI3Kα is considered one of the major determinants of cancer therapy resistance. Despite preclinical and clinical evaluation of PI3Kα inhibitors in various tumor entities, including head and neck squamous cell carcinoma (HNSCC), it remains elusive how conventional radiochemotherapy can be enhanced by concurrent PI3K inhibitors and how PI3K deactivation mechanistically exerts its effects. Here, we investigated the radiochemosensitizing potential and adaptation mechanisms of three PI3Kα inhibitors, Alpelisib, Copanlisib and AZD8186, in eight HNSCC models grown under physiological, three-dimensional matrix conditions. We demonstrate that all three inhibitors enhance radio- and radiochemosensitivity in the majority of HNSCC cell models (= responders) in a manner independent of PIK3CA mutation status. However, Alpelisib promotes MAPK signaling in non-responders compared to responders without profound impact on Akt, NFκB, TGFβ, JAK/STAT signaling and DNA repair. Bioinformatic analyses identified unique gene mutations associated with extracellular matrix to be more frequent in non-responder cell models than in responders. Finally, we demonstrate that targeting of the cell adhesion molecule β1 integrin on top of Alpelisib sensitizes non-responders to radiochemotherapy. Taken together, our study demonstrates the sensitizing potential of Alpelisib and other PI3K inhibitors in HNSCC models and uncovers a novel β1 integrin-dependent mechanism that may prove useful in overcoming resistance to PI3K inhibitors.

Keywords: HNSCC; PI3K; beta1 Integrin; Targeting; Radiochemosensitization

Permalink: https://www.hzdr.de/publications/Publ-37487


Data publication: Numerische Untersuchung der Rayleigh-Bénard-Konvektion in einem Flüssigmetall unter dem Einfluss einer zeitlich modulierten gezeitenartigen Kraft

Röhrborn, S.

Abstract

Simulationsdaten der Dissertation: "Numerische Untersuchung der Rayleigh-Bénard-Konvektion in einem Flüssigmetall unter dem Einfluss einer zeitlich modulierten gezeitenartigen Kraft"

Keywords: Rayleigh-Bénard; Magnetohydrodynamics; liquid metal flow; CFD; electromagnetic forcing; Flüssigmetall; Elektromagnetuische Anregung

Downloads

Permalink: https://www.hzdr.de/publications/Publ-37486


Steam Line Break Analysis in NuScale SMR with the Coupled System Code ATHLET-DYN3D in the Framework of the EU H2020 McSAFER

Diaz Pescador, E.; Jobst, M.; Grahn, A.; Kliem, S.

Abstract

The small modular reactor (SMR) NuScale is modelled by Helmholtz-Zentrum Dresden-Rossendorf (HZDR) in the framework of the EU H2020 McSAFER project. NuScale is a SMR of integral pressurized water reactor (iPWR) type, operated by light water driven by natural circulation in all operation modes. This work summarizes the modelling approach of NuScale SMR with the coupled thermalhydraulic/neutronic code ATHLET-DYN3D. The 3-D neutronic calculation is performed with a XS-library developed with Serpent based on 4-neutron group homogenized nuclear constants for fuel and heavy reflector. The paper presents results and discussion from a non-isolable double-ended steam line break (SLB) sequence, based on the Design Certification Application (DCA) report. The simulation results at steady-state show agreement with the reference values from the DCA report. The transient calculation shows that both steam generators (SGs) boil-off and the reactor is tripped upon “low main steam pressure” function. The rapid depressurization and high steam rates towards the break lead to enhanced primary-tosecondary heat removal. However, the reactor symmetry imposed by the arrangement of the two compact SGs enhances flow mixing and limits coolant temperature reduction at the core inlet, thereby preventing a
power excursion and highlighting the inherent safety of this reactor design. Acceptance criterion is met
regarding pressure increase below acceptable limits inside the intact SG after steam isolation valve closure.

Keywords: NuScale; SMR; ATHLET-DYN3D; SLB; McSAFER

  • Contribution to proceedings
    20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20), 20.-25.08.2023, Washington DC, United States of America
  • Lecture (Conference)
    20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20), 20.-25.08.2023, Washington DC, United States of America

Permalink: https://www.hzdr.de/publications/Publ-37485


In-bulk temperature profile mapping using Fiber Bragg Grating in fluids

Su, S.; Niu, T.; Vogt, T.; Eckert, S.

Abstract

In this study we investigate the capabilities of Fiber Bragg Gratings (FBG) sensors to
measure temperature variations in the bulk of liquids. In particular, we want to show to what extent
the utilisation of optical glass fibers without encapsulation can fulfill the requirements with regard to
robustness and measurement accuracy. We built an experimental test setup as a benchmark, in which
23 FBG measuring positions are instrumented in parallel with thermocouples for validation. We
present a special assembly procedure in which the fiber is placed under a defined tension to improve
its stiffness and immobility for given flow conditions. We propose the application of a single FBG
sensor as a strain reference measuring the strain effect in real time and allowing for accurate relative
temperature measurements at the other FBG sensor points. The further addition of a well-calibrated,
strain-independent thermometer at the reference FBG provides satisfactory absolute temperature
data. We apply this method on two test cases: (i) a stable gradient in the liquid metal GaInSn and (ii)
a local source of heat in water. We succeeded in accurately tracking the temperature variation both
spatially and temporally.

Keywords: optical fiber; fiber Bragg Grating (FBG); temperature sensor; in-bulk measurement; multiplexing; temperature mapping

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37484


Kontaktlose Materialidentifikation und Digitalisierung für die Realisierung geschlossener Stoffkreisläufe; Acamonta 2022

Röder, C.; Fuchs, M.; Abend, T.; Beyer, J.; Schüler, N.; Lorenz, S.; Dornich, K.; Gloaguen, R.; Heitmann, J.

Abstract

Auf eine der drängendsten Fragen unserer modernen Gesellschaft, nämlich nach einem nachhaltigen, verantwortungsbewussten Umgang mit unseren natürlichen Rohstoffquellen, ist der Aufbau einer effizienten Kreislaufwirtschaft eine mögliche Antwort. Den Ressourceneinsatz, die Emissionen und den Energieverbrauch gilt es durch den Einsatz geschlossener Stoffkreisläufe zu minimieren. Das bedeutet, dass wir uns neben einer effizienten Nutzung der Rohstoffe auch mit einer exponentiell steigenden Abfallmenge auseinandersetzen müssen. Bisher wird allerdings nur ein kleiner Anteil aller Abfälle recycelt. Ein Grund dafür ist die zunehmende Komplexität der global anfallenden Recycling-Stoffströme, die eine rasche Weiterentwicklung der Inline-Rohstoffcharak-
terisierung unabdingbar macht.

Keywords: Rohstoffe; Charakterisierung; Recycling

  • Acamonta - Zeitschrift für Freunde und Förderer der Technischen Universität Bergakademie Freiberg 29(2022)1, 23-26

Permalink: https://www.hzdr.de/publications/Publ-37483


Einzigartige Forschungsinfrastruktur für die Prozessmetallurgie - Das neue Metallurgie-Technikum am Helmholtz Institut Freiberg für Ressourcentechnologie; Acamonta 2021

Recksiek, V.; Bestian, M.; Kelly, N.

Abstract

Am 9. September 2021 wurde das neugebaute Metallurgie-Technikum am Standort des Helmholtz-Instituts Freiberg für Ressourcentechnologie (HIF), das
zum Helmholtz-Zentrum Dresden-Rossendorf (HZDR) gehört und eine gemeinsame Gründung des HZDR und der TU Bergakademie Freiberg (TU BAF) ist, eingeweiht. In der neuen Versuchshalle werden künftig Forschungsergebnisse zur pyro- bzw. hydrometallurgischen Rückgewinnung wirtschaftsstrategischer Metalle zum (Wieder-) Einsatz in modernen Schlüsseltechnologien aus dem Labor- in den Pilotmaßstab überführt und so für den Transfer in die Industrie vorbereitet. Dazu werden innovative Verfahren miteinander kombiniert und digital untereinander vernetzt. Das Technikum bietet damit exzellente Voraussetzungen, um neue Technologien und Prozesse zu erproben, zu automatisieren und zu optimieren.

Keywords: Metallurgie; Technikum; Freiberg

Involved research facilities

  • Metallurgy Technical Centre
  • Acamonta - Zeitschrift für Freunde und Förderer der Technischen Universität Bergakademie Freiberg 28(2021)1, 100-100

Permalink: https://www.hzdr.de/publications/Publ-37482


Neue Gangstudien bieten systemisches Verständnis für die Entstehung hydrothermaler Lagerstätten im Erzgebirge; Acamonta 2021

Burisch-Hassel, M.; Frenzel, M.; Guilcher, M.; Swinkels, L. J.; Haschke, S.; Reinhardt, N.; Gutzmer, J.

Abstract

Als Professor der Geognosie an der Bergakademie Freiberg gilt Bernhard von Cotta als Begründer der Erzlagerstättenlehre. Dieser Ruf wird zumeist zurückgeführt auf die Publikation des Lehrbuchs „Die Lehre von den Erzlagerstätten" im Jahr 1850 (von Cotta, 1859). Darüber hinaus hat Prof. von Cotta aber auch durch die Publikation der als „Gangstudien“ betitelten vier Bände in den Jahren 1850-1862 Herausragendes für die Erzlagerstättenlehre geleistet. Im Vorwort zum ersten Band definiert von Cotta sehr klar als Zweck der Gangstudien „über die Bedingungen der Erzführung womöglich einiges Licht zu verbreiten; also Materialien zu einer wissenschaftlichen Wünschelruthe zu liefern, welche künftig dem Bergmann auf seinen dunklen Pfaden als eine Leitschnur dienen könnte.” Motiviert wurde die Publikation der Gangstudien dabei insbesondere durch die proaktive Rolle des Oberbergamts, welches „eine sorgfältige Untersuchung der hiesigen Erzgänge und vorzüglich ihrer Veredelungs- oder Verunedelungsursachen angeordnet” hatte. Daher richtete von Cotta den Fokus der Gangstudien zunächst klar auf die Bildung der Erzlagerstätten in der Region. In der durch Bernhard von Cotta zusammengestellten
Publikationsreihe findet sich in der Folge eine große Zahl von Beiträgen, welche durchaus als bahnbrechend für ihre Zeit gelten.
Die vorerst letzte Phase des Bergbaus in Freiberg endete im Jahre 1969; der Bergbau im Erzgebirge fand mit der deutschen Wiedervereinigung im Jahr 1991 ein unvermitteltes Ende. In den seither vergangenen Jahrzehnten hat die Kenntnis um die Entstehung der Erzlagerstätten im Erzgebirge mit modernen geowissenschaftlichen Erkenntnissen und Konzepten nicht mitgehalten. Dadurch ging viel Kompetenz verloren – aus modellbasierten Annahmen früherer Bearbeiter wurden „in Stein gehauene” Paradigmen, die weitestgehend unkritisch weitergegeben wurden. Mit dem Ziel, diesen offensichtlichen und eklatanten Missstand zu beheben, wurde im Jahr 2018 die ESF Nachwuchsforschergruppe „Mineral Systems Analysis” gegründet. Ermöglicht durch öffentliche Fördermittel der Europäischen Union und des Freistaats Sachsen haben sich seither zwei Doktorandinnen und zwei Doktoranden, flankiert durch eine Vielzahl von Master- und Bachelor-Student*innen unter der Leitung von Mathias Burisch mit der Entstehung verschiedener hydrothermaler Lagerstättentypen im Erzgebirge befasst. Die Arbeiten der Nachwuchsgruppe am Institut für Mineralogie der TU Bergakademie Freiberg wurden durch Max Frenzel und Jens Gutzmer am Helmholtz-Institut Freiberg für Ressourcentechnologie unterstützt. Die Forschung basierte dabei zum Teil auf dem Studium von hervorragenden Proben der geowissenschaftlichen Sammlungen der TU Bergakademie Freiberg, der Wismut GmbH und dem Bohrkernarchiv des
Sächsischen Landesamts für Umwelt, Landwirtschaft und Geologie. Die enge und vertrauensvolle Zusammenarbeit mit den Firmen, die aktuell im Bereich von Rohstofferkundung und -abbau im Erzgebirge beteiligt sind, lieferte einen weiteren wichtigen Baustein für den Erfolg der Gruppe. Die Entwicklung eines modernen Verständnisses der räumlich-zeitlichen Entwicklung der Erzlagerstätten im Erzgebirge und die Integration der lagerstättenbildenden Prozesse mit relevanten Prozessen der regional- und lokalgeologischen Entwicklung stand im Fokus der Forschung – ganz im Sinne von Bernhard von Cotta. Daher sind die wichtigsten Resultate der Arbeit der Nachwuchsforschergruppe, die im Folgenden vorgestellt werden sollen, in das aktuelle Verständnis der geotektonischen Entwicklung eingebettet. Hier werden insgesamt 10 peer-review Artikel der Mineral Systems Analysis Gruppe zusammengefasst, die alle in der Referenzliste aufgeführt sind und bei Interesse zur weiteren Vertiefung gelesen werden können.

Keywords: Erzgebirge; Lagerstättenlehre; Mineral Analysis Group

  • Acamonta - Zeitschrift für Freunde und Förderer der Technischen Universität Bergakademie Freiberg 28(2021)1, 83-87

Permalink: https://www.hzdr.de/publications/Publ-37481


Helios Lab - Ein gemeinsames Labor zwischen Helmholtz-Institut Freiberg für Ressourcentechnologie und der Technischen Universität Bergakademie Freiberg; Acamonta 2021

Gloaguen, R.; Lorenz, S.

Abstract

Wenn wir die negativen Auswirkungen menschlicher Aktivitäten auf Klima und Umwelt reduzieren wollen, müssen wir uns zwangsläufig mit einer exponentiell steigenden Abfallmenge auseinandersetzen. Solche Abfälle beinhalten nicht nur die Reste unseres alltäglichen Konsums wie z. B. Elektroschrott. Im Bergbau wird beispielsweise nur ein kleiner Teil des geförderten Gesteins tatsächlich für die Gewinnung neuer Rohstoffe genutzt, der größere Rest landet auf Halden. Zusätzlich zu solchen primären Abfällen fallen große Mengen an Sekundärabfällen wie Verbrennungsrückstände und Schlacken an. Ein besseres Recycling unserer Reststoffe ist zu einer dringlichen Aufgabe geworden, und auch wenn eine vollständige Kreislaufwirtschaft in Zukunft Utopie bleiben muss, so sollten wir uns doch so viel wie möglich daran annähern.

Keywords: Recycling; Sortierung; Charakterisierung; Rohstoffe

  • Acamonta - Zeitschrift für Freunde und Förderer der Technischen Universität Bergakademie Freiberg 28(2021)1, 37-38

Permalink: https://www.hzdr.de/publications/Publ-37480


recomine - Ganzheitliche Lösungsansätze für Bergbaualtlasten durch Kombination von Umwelt-, Ressourcentechnologie und Digitalisierung; Acamonta 2021

Büttner, P.; Engelhardt, J.

Abstract

Neue Wege im Umgang mit Bergbaualtlasten
In den vergangenen zehn Jahren befassten sich mehrere nationale und europäische Förderprogramme mit dem Ressourcenpotenzial von Bergbauabfällen (Grobbergematerial, Spülhalden und Hüttenschlacken), wobei der Schwerpunkt auf der Erschließung neuer Quellen für kritische Rohstoffe lag, die von
der Europäischen Kommission als äußerst wichtig für die europäische Hightech-Industrie definiert wurden. Sie beruhen auf der europäischen und nationalen Ressourcenstrategie. Eines dieser Programme in Deutschland war das vom Bundesministerium für Bildung und Forschung (BMBF) geförderte Programm
„r3 - Strategische Metalle und Mineralien - Innovative Technologien für Ressourceneffizienz", das im Jahr 2012 startete. Ziel war es, die Versorgung der deutschen Wirtschaft mit strategisch bedeutsamen Metallen und Mineralien zu sichern und Projekte in den Bereichen Recycling, Substitution und reduziertem Ressourcenverbrauch, Urban Mining und Methoden zur Bewertung der Ressourceneffizienz zu fördern.

Keywords: recomine; Bergbaualtlasten; Ressourcentechnologie

  • Acamonta - Zeitschrift für Freunde und Förderer der Technischen Universität Bergakademie Freiberg 28(2021)1, 32-33

Permalink: https://www.hzdr.de/publications/Publ-37479


Innovationsplattform für die Kreislaufwirtschaft der Zukunft - Das Helmholtz-Institut Freiberg für Ressourcentechnologie feiert 10-jähriges Bestehen und hat noch viel vor; Acamonta 2021

Jentzsch, A.-K.

Abstract

Die Entwicklung, die das Helmholtz-Institut Freiberg für Ressourcentechnologie (HIF) seit seiner Gründung genommen hat, ist eine Erfolgsgeschichte. Denn wer hätte vor 10 Jahren gedacht, dass die Idee, ein Institut für Ressourcentechnologie zu gründen, so schnell Früchte tragen würde! Eine wesentliche Rol-
le spielt dabei, dass es ein Helmholtz-Institut geworden ist, denn Institute dieses Namens geben strategischen Partnerschaften zwischen Zentren der Helmholtz-Gemeinschaft und Universitäten eine besondere Intensität. In unserem Fall ist es die dauerhaft enge Zusammenarbeit auf dem Gebiet der Ressourcentechnologie zwischen dem Helmholtz-Zentrum Dresden-Rossendorf (HZDR) und der TU Bergakademie Freiberg. Der Namensgeber der Gemeinschaft, Hermann von Helmholtz, vertrat eine Naturwissenschaft, die Brücken zwischen Medizin, Physik und Chemie schlägt. Seine bahnbrechenden Forschungen und Entwicklungen verknüpften Theorie, Experiment und praktische Anwendung miteinander. Diesen bewährten Ansatz möchte das HIF mit dem Ausbau eines Campus für Ressourcentechnologie und Nachhaltigkeit am Standort Chemnitzer Straße 40 in Freiberg fortschreiben und auch damit ein national sowie international ausgerichtetes Kompetenzzentrum zur Erforschung, Entwicklung und Bewertung innovativer Ressourcentechnologien im Kontext einer dem Nachhaltigkeitsprinzip verpflichteten Kreislaufwirtschaft sein. Mit dem Forschungscampus wird es möglich, Innovationen für den nachhaltigen Umgang mit komplex zusammengesetzten Rohstoffen bzw. Stoffströmen voranzutreiben und die Aufbereitung und Rückgewinnung dieser
Rohstoffe auf hohem wissenschaftlich-technischen Niveau vom Labor- in den Pilotmaßstab zu überführen. Ziel ist es dabei, die entsprechenden Technologieentwicklungen zeitnah in die industrielle Praxis zu bringen. Damit steigt die Attraktivität des Standorts Freiberg nicht nur als Forschungspartner der TU Bergakademie Freiberg, sondern auch hinsichtlich der Zusammenarbeit mit sächsischen, nationalen und internationalen Partnern aus Wissenschaft und Wirtschaft.

Keywords: HIF; 10 Jahre; Ressourcentechnologie; Kreislaufwirtschaft

  • Acamonta - Zeitschrift für Freunde und Förderer der Technischen Universität Bergakademie Freiberg 28(2021)1, 25-27

Permalink: https://www.hzdr.de/publications/Publ-37478


Bergbauexploration einmal anders: ein europäisches Projekt, um neue Werte in den Sektor zu bringen; Acamonta 2020

Kirsch, M.; Gloaguen, R.; Ajjabou, L.

Abstract

Jedes technische Gerät, das in unserer Gesellschaft eingesetzt wird, benötigt Materialien, die entweder aus unserer natürlichen Umwelt („Primärrohstoffe“)
oder aus der Wiederverwendung von Materialien in bestehenden Produkten (Recycling, „Sekundärrohstoffe“) gewonnen werden. Darüber hinaus nimmt die von der Industrie benötigte Materialmenge in dem Maße zu, wie der menschliche Reichtum und die Bevölkerung wachsen. Selbst in einer Kreislaufwirtschaft müssen die Bodenschätze die Sekundärrohstoffe ergänzen und eine grundlegende Basis für unseren materiellen Wohlstand bilden. Natürlich stellen die Gewinnung von Primärrohstoffen, die Notwendigkeit eines effizienteren Recyclings und die Entsorgung von Abfällen, die nicht effizient genutzt oder recycelt werden können, unsere Gesellschaft vor große und komplexe Herausforderungen. Zum Beispiel sind Rohstoffe für die Herstellung
von Batterien, die eine Schlüsseltechnologie für den Energiewandel darstellen, unerlässlich. Während in den kommenden Jahren mit einem exponentiellen Anstieg der Nachfrage nach Batterien gerechnet wird, war die Entwicklung einer wettbewerbsfähigen und lebensfähigen Batterieherstellungsindustrie noch nie so wichtig wie heute, und in ihrem Kern die Versorgung mit sogenannten „kritischen“ Metallen. Auf der anderen Seite steht die starke Nachfrage nach Rohstoffen in unserer postindustriellen Gesellschaft im Gegensatz zu den zunehmenden Schwierigkeiten bei der Suche und Erschließung neuer Mineralvorkommen.

Keywords: Exploration; primäre und sekundäre Rohstoffe; Projekt INFACT; Erkundung

  • Acamonta - Zeitschrift für Freunde und Förderer der Technischen Universität Bergakademie Freiberg 27(2020)1, 45-47

Permalink: https://www.hzdr.de/publications/Publ-37477


Eine Renaissance der Freiberger Flotationsforschung – A Fine Future in der Helmholtzgemeinschaft; Acamonta 2019

Rudolph, M.; Eckert, K.

Abstract

Die Flotation, ein Trennprozess basierend auf der unterschiedlichen Benetzbarkeit von Mikropartikeln und wichtigster Vertreter der Heterokoagulationstrennprozesse, erwuchs seit Ende des 19. Jahrhunderts zu einem der bedeutesten Aufbereitungsprozesse für verschiedenste Erztypen. Es wird sogar davon ausgegangen, dass ohne die Flotation die Versorgung des wachsenden Bedarfs vieler wichtiger Rohstoffe, z. B. Kupfer, gegen Mitte des 20. Jahrhunderts zum Erliegen gekommen wäre. Freiberg war bis zu Zeiten der deutschen Wiedervereinigung ein weltweit führender Standort in der Flotationsforschung sowohl in ihren Grundlagen als auch für die industrielle Anwendung. Mit der Gründung des Helmholtz-Instituts Freiberg für
Ressourcentechnologie (HIF) des Helmholtz-Zentrums Dresden-Rossendorf (HZDR) an der TU Bergakademie Freiberg im Jahr 2011 wurde begonnen, diese Kernkompetenz in Freiberg und Dresden wiederaufzubauen. In diesem Artikel werfen wir einen Blick auf den regional historischen Bezug zum Flotati-
onsprozess und dessen Erforschung, beschreiben den Neuaufbau der Flotationsforschung von 2011 bis heute, stellen das wichtige vom HZDR koordinierte EU-Projekt „FineFuture“ vor und geben einen Einblick in die aktuellen Forschungsakzente im Bereich Flotation.

Keywords: Flotation; Fine Future; Trennprozesse; Aufbereitung

  • Acamonta - Zeitschrift für Freunde und Förderer der Technischen Universität Bergakademie Freiberg 26(2019)1, 38-39

Permalink: https://www.hzdr.de/publications/Publ-37476


rECOmine - Regionales Netzwerkprojekt für ressourcenorientierte Umwelttechnologien; Acamonta 2018

Grigoleit, J.; Büttner, P.; Hesse, A.; Peuker, U. A.; Gutzmer, J.

Abstract

Mit dem regionalen Verbundvorhaben "rECOmine - Ressourcenorientierte Umwelttechnologien für das 21. Jahrhundert" beteiligen sich die TU Bergakademie Freiberg und das Helmholtz-Institut Freibger für Ressourcentechnologie (HIF) gemeinsam mit weiteren Partnern am BMBF-Programm "WIR! - Wandel durch Innovation in der Region". Mit diesem Programm sollen durch die Förderung regionaler themenbezogener Innovationscluster Leuchttürme für den Strukturwandel geschaffen werden, von denen Impulse für die wirtschaftliche Entwicklung ganzer Regionen ausgehen, wobei in der aktuellen Ausschreibung der Fokus vor allem bei den strukturschwachen ländlichen Regionen in Ostdeutschland liegt. Von ursprünglich 105 eingereichten Konzepten wurden 32 Vorhaben mit besonders guten Erfolgsaussichten ausgewählt und aufgefordert, sich mit entsprechend fundierten Innovationskonzepten für eine Förderung im Umfang von bis zu 15 Mio. EUR zu bewerben, darunter auch das Bündnis rECOmine.

Keywords: recomine; Netzwerk; HIF; Freiberg; TU Freiberg; Bündnis; Strukturwandel

  • Acamonta - Zeitschrift für Freunde und Förderer der Technischen Universität Bergakademie Freiberg 25(2018)1, 85-87

Permalink: https://www.hzdr.de/publications/Publ-37475


Peptide für die spezifische Interaktion mit Mineralen; Acamonta 2018

Lederer, F.; Braun, R.; Pollmann, K.

Abstract

Recycling ist eine wichtige Komponente der Kreislaufwirtschaft, um Ressourcen zu schonen. Auch die Biologie wird dazu zukünftig ihren Beitrag leisten. Dabei steht das Recycling von Edelmetallen und Seltenen Erdelementen (SEE), welche in Elektronikprodukten verbaut sind, im Mittelpunkt eines Forschungszweiges der Abteilung Biotechnologie am Helmholtz-Institut Freiberg für Ressourcentechnologie (HIF). Die Wissenschaftler erforschen biologie-basierte Prozesse zum Recycling wirtschaftsstrategischer Metalle aus z. B. Smartphones oder Windturbinen. Ziel der Forschung ist es, Bioreagenzien für Flotationsverfahren – also die Aufbereitung feinster Teilchen – zu entwickeln. Die Phagen, also Viren die Bakterien als Wirtsorganismus nutzen, liefern dabei die erforderliche Materialspezifität und Affinität, um die Metalle selektiv aus einem Materialgemisch abzutrennen und gleichzeitig den bisher notwendigen Einsatz giftiger Trennchemikalien zu reduzieren.

Keywords: Recycling; Biotechnologie; Peptide; Minerale; Seltene Erden

  • Acamonta - Zeitschrift für Freunde und Förderer der Technischen Universität Bergakademie Freiberg 25(2018)1, 60-63

Permalink: https://www.hzdr.de/publications/Publ-37474


Neues Wissen zur Metallogenese im Freiberger Revier: 850 Jahre nach dem Silberfund - und (k)ein bisschen klüger?; Acamonta 2018

Burisch-Hassel, M.; Bauer, M. E.; Frenzel, M.; Hartmann, A.; Kehrer, C.; Ostendorf, J.; Seifert, T.; Gutzmer, J.

Abstract

Im Jahr 2018 feiert die Stadt Freiberg das 850. Jubiläum des ersten Silberfundes im Jahre 1168. Dieses Ereignis gilt als Auslöser für den intensiven Bergbau im Freiberger Distrikt, der von 1168 bis 1969 andauerte. Trotz des langanhaltenden Silberabbaus ist das Ressourcenpotential des Freiberger Distriktes keineswegs erschöpft, da die meisten Bergbaubetriebe aus politischen, technischen oder auch ökonomischen Faktoren eingestellt wurden und nicht etwa deswegen, weil kein Erz mehr vorhanden gewesen sei. Die aktuelle Explorationstätigkeit von Globex Mining Inc. in den nördlichen Randgebieten verdeutlicht dieses Potential (http://www.globexmining.com).
Neben dem Bergbau und der damit verbundenen sozio-ökonomischen Bedeutung für die Region war der Silberbergbau maßgeblicher Grund für die Entstehung und Entwicklung der TU Bergakademie Freiberg (TUBAF) in 1756. Auch die Entstehung der Lagerstättenforschung als wissenschaftliche Fachrichtung ist letztlich eine Konsequenz des ersten Silberfundes. Speziell in Bezug auf die Lagerstättenforschung im Freiberger Distrikt sind Werner (1791), Breithaupt (1849), von Cotta (1850), Müller (1901) und Baumann (1965) zu nennen, wobei von Cotta (1850) das weltweit erste Buch zur Lagerstättenforschung als Fach- und Lehrrichtung verfasste. Ohne die Leistung dieser Vorreiter schmälern zu wollen, sind deren Arbeiten überwiegen beschreibend, was dem damaligen Kenntnisstand und den begrenzten analytischen Möglichkeiten entsprach. Gerade weil viele der Bergwerke heute nicht mehr für die Beprobung zugänglich sind, bilden diese beschreibenden Arbeiten dennoch ein essentielles Fundament des Wissens für moderne Forschungsprojekte. Ziel aktueller Forschungsarbeiten ist es, die geologischen Bildungsbedingungen (Druck, Temperatur, Zusammensetzung der erzbildenden hydrothermalen Lösungen), Bildungsprozesse (Quelle, Transport und Ausfällung) und absoluten Alter der jeweiligen Mineralisationsphasen genauer zu bestimmen. Es sind eben diese Kenntnisse, die dazu dienen, genetische Modelle für den Freiberger Distrikt zu entwickeln. Letztere sind die Grundlage für eine erfolgreiche Neubewertung und Neuerkundung (McCuaig et al., 2010; Occhipinti et al., 2016).
Die Professur für Lagerstättenlehre und Petrologie der TU Bregakademie Freiberg und das Helmholtz-Institut Freiberg für Ressourcentechnologie haben mehrere gemeinsame Forschungsprojekte ins Leben gerufen, die die eklatanten Wissenslücken zur Genese des Freiberger Distrikts schließen wollen. Mit sorgfältig angelegten Studien und modernen Analyseverfahren soll das Verständnis der Entstehung der Freiberger Gänge auf einen aktuellen Forschungsstand gebracht werden. Konkret wird dabei ein starker Fokus auf die Analyse von Flüssigkeitseinschlüssen, Haupt- und Spurenelementanalysen von Erzmineralen und die Altersbestimmung von Erz- und Begleitmineralen (radiogene Isotopenanalysen) gelegt.

Keywords: Freiberg; Bergbau; Lagerstättenforschung; Geologie; Silber

  • Acamonta - Zeitschrift für Freunde und Förderer der Technischen Universität Bergakademie Freiberg 25(2018)1, 8-13

Permalink: https://www.hzdr.de/publications/Publ-37473


EIT Raw Materials: Neue Perspektiven für die europäische Rohstoffforschung; Acamonta 2015

Gutzmer, J.; Klossek, A.; Pereira, T.

Abstract

Obwohl Europa über ein enormes Innovationspotenzial verfügt, entstehen besonders im Rohstoffsektor nur wenige Start-up-Unternehmen. Neuartige Technologien und Prozesse schaffen – trotz exzellenter Forschung – zu selten den Sprung auf den Markt. Zwar stehen den meisten Start-ups in der frühen Entwicklungsphase öffentliche Fördermittel, wie z. B. Gründer-Fonds, zur Verfügung, doch fehlt ihnen danach oft das nötige Geld für den entscheidenden Wachstumsschub hin zu einer kapitalmarktbasierten Eigenfinanzierung. Häufig wird diese Phase als „Tal des Todes“ bezeichnet. Ein Unternehmen, das sie überlebt, erhält Zugang zu einem Markt, der Investoren bereithält, die voraussichtlich tragfähige Geschäftsmodelle im Weiteren unterstützen.
Damit mehr Start-up-Unternehmen zukünftig dieses Tal des Todes überwinden und so das Innovationspotenzial des europäischen Rohstoffsektors auch ausgeschöpft werden kann, wollen 115 europäische Partner – zu denen das zum Helmholtz-Zentrum Dresden-Rossendorf gehörige Helmholtz-Institut Freiberg für Ressourcentechnologie und die TU Bergakademie Freiberg zählen – gemeinsam einen wichtigen Paradigmenwechsel anstoßen. Wettbewerbsfähigkeit, Wachstum und Attraktivität des europäischen Rohstoffsektors sollen durch radikale Innovation, aber auch Unternehmergeist gesteigert werden. Ziel ist es, diesen wichtigen Industriesektor zu einer strategischen Säule der Wirtschaft der EU zu machen. Das Europäische Institut für Innovation und Technologie (EIT) – eine Organisation der EU – teilt diese Vision. Es hat deshalb Anfang Dezember 2014 ein Konsortium, koordiniert vom Helmholtz-Zentrum Dresden-Rossendorf und von der Fraunhofer-Gesellschaft, damit beauftragt, eine Wissens- und Innovationsgemeinschaft (Knowledge and Innovation Community, KIC) für den Rohstoffsektor zu etablieren. Das neue KIC trägt den Namen „EIT Raw Materials“. Es bringt Unternehmen und Forschungseinrichtungen aus 22 EU-Mitgliedsstaaten unter einem Dach zusammen. Damit ist EIT Raw Materials das größte Rohstoffnetzwerk der Welt, das
auf ideale Weise ein für alle KIC charakteristisches Wissensdreieck aus Ausbildung, Forschung und Industrie erzeugt. Durch seine enorme Anzahl von Partnern verfügt das Netzwerk über Kompetenzen aus dem gesamten Spektrum des Wissens und Forschens über die mineralischen und metallhaltigen Rohstoffe und deckt alle Glieder der Rohstoff-Wertschöpfungskette vollständig ab – von der Erkundung über die Aufbereitung bis hin zu Recycling und
der Substitution von Ressourcen. Diesen strategischen Vorteil will das Institut dazu nutzen, um Barrieren, die die Zusammenarbeit zwischen Hochschulen, Forschungseinrichtungen und Unternehmen behindern, zu überwinden. Auf diese Weise soll der Dialog zwischen den involvierten Potenzialen und Bereichen vor allem durch Verständigung über jeweils anzugehende Ziele sowie durch den Austausch von Ideen und Forschungsergebnissen vereinfacht werden. Nur so kann sich der europäische Rohstoffsektor und können sich auch die an ihn angrenzenden Branchen in einen Wachstumsmarkt für
Investitionen, Innovationen und talentierte Entrepreneure verwandeln. Damit dies gelingt, müssen sich Politiker, Unternehmer und Wissenschaftler
darüber im Klaren sein, welche Herausforderungen der europäische Rohstoffsektor zu bewältigen hat. Denn im Vergleich zu Ländern wie China, Russland oder den USA ist die EU bei der Versorgung mit existenziell wichtigen mineralischen und metallischen Rohstoffen noch deutlich stärker vom globalen Handel abhängig. Eine der wichtigsten Aufgaben des EIT Raw Materials wird es deshalb sein, neue ökonomisch und ökologisch fundierte Konzepte
zu entwickeln: für die Nutzung heimischer Lagerstätten, den Bergbau unter schwierigen, oft urbanen Bedingungen – ebenso wie für den Ausbau einer wettbewerbsfähigen rohstoffverarbeitenden und sonstigen rohstoffnahen Industrie. Eine weitere Herausforderung wird sein, mit neuen Technologien und Nutzungskonzepten den Weg für eine effiziente und nachhaltige Kreislaufwirtschaft zu ebnen. Ausgediente Hightech-Produkte etwa, wie Smartphones oder Laptops, dürfen nicht mehr als Müll angesehen werden, sondern vielmehr als Quelle für die Rückgewinnung wertvoller Rohstoffe.
Um diese und weitere Aufgaben meistern zu können, gilt es, alle Partner des KIC optimal miteinander zu verknüpfen. In lokalen Zentren, den sog. Co-Location Centers (CLC), bündelt das Netzwerk dafür transnationale Regionen mit thematischen Schwerpunkten. Insgesamt gibt es sechs solcher Zentren, und zwar in Italien, Frankreich, Polen, Belgien, Finnland und Schweden. Das EIT Raw Materials koordiniert sie von seinem Hauptsitz in Berlin aus. Die deutschen Partner beteiligen sich an den drei CLC in Frankreich, Belgien und Polen.

Keywords: EIT; Raw Materials; KIC; Freiberg; TU Freiberg; EU; Rohstoffforschung; Netzwerk

  • Acamonta - Zeitschrift für Freunde und Förderer der Technischen Universität Bergakademie Freiberg 22(2015)1, 91-93

Permalink: https://www.hzdr.de/publications/Publ-37472


Hochtechnologiemetalle als industrielle Beiprodukte - Bedeutung von Geometallurgie und Rohstoffcharakterisierung; Acamonta 2015

Frenzel, M.; Krause, J.; Bachmann, K.; Gutzmer, J.

Abstract

Indium, ein silberfarbenes, weiches, dem Zinn sehr ähnliches Metall, hat eine ganz besondere Beziehung zu Freiberg: nicht nur, dass es im Jahr 1863 von Reich und Richter an der Bergakademie entdeckt wurde; auch das für die Arbeit der beiden Entdecker verwendete Probenmaterial entstammte dem lokalen
Bergbau. Heutzutage kommt Indium große Bedeutung als einem der wichtigsten Hochtechnologiemetalle zu, ohne das der weltweit verbreitete Einsatz von Smartphones und Flachbildschirmen nicht möglich wäre. Gewonnen wird es hauptsächlich als Beiprodukt aus Zinkund untergeordnet auch aus Kupfererzen. D. h. es gibt keine Indiumbergwerke, sondern Indium wird bei der Verhüttung der Erze dieser beiden Hauptmetalle gewonnen. Da aber der Wert des in den Erzen enthaltenen Indiums oft sehr viel geringer ist als der der Hauptmetalle (< 10 %), hat seine Konzentration keinen Einfluss darauf, welche Erze abgebaut werden. Das führt dazu, dass die weltweit zur industriellen Verfügung stehende Menge an Indium letztendlich durch den Umfang der (Kupfer- und) Zinkproduktion begrenzt ist. Diese Limitation erzeugt ein großes pozenzielles Versorgungsrisiko. Indium ist damit ein typisches Beispiel eines Hochtechnologiemetalls, das ausschließlich als Beiprodukt gewonnen werden kann.
Am Beispiel der polymetallischen Lagerstätte Neves-Corvo in Portugal soll in diesem Beitrag dargestellt werden, welche Informationen zur Verfügung stehen müssen, um die Nutzung von Beiprodukten – wie eben von Indium – zu ermöglichen. Die Lagerstätte Neves-Corvo beherbergt mit einem zzt. noch verbliebenen Gesamtinhalt von > 1.000 t Indium die größte bekannte Konzentration dieses Elements in einer abbauwürdigen Lagerstätte in Europa. Jedoch profitiert das Unternehmen Somincor, das die Lagerstätte Neves-Corvo abbaut, momentan nicht von diesem Reichtum: Die in Neves-Corvo produzierten Cu- und Zn-Konzentrate erreichen in der Regel nicht die von den Hütten für die Vergütung verlangten Indium-Mindestgehalte. Ziel der in diesem Artikel beschriebenen Arbeit ist es, auf geometallurgischen Untersuchungen aufbauend Nutzungskonzepte zu entwickeln, die dem Unternehmen bei der vollen
Ausschöpfung seines Indiumpotenzials helfen können. Die dazu durchgeführte Studie ist – unseres Wissens – die weltweit erste ausführliche geometallurgische Studie zur Konzentrationsverteilung und Gewinnbarkeit von Indium als Beiprodukt. Da diese Studie noch nicht abgeschlossen ist, werden im Folgenden nur vorläufige Ergebnisse präsentiert.

Keywords: Geometallurgie; Indium; Rohstoffe; Bergbau; Metalle; Lagerstätte Neves-Corvo

  • Acamonta - Zeitschrift für Freunde und Förderer der Technischen Universität Bergakademie Freiberg 22(2015)1, 25-28

Permalink: https://www.hzdr.de/publications/Publ-37471


Beschleunigungsmessung als Grundlage für die Strömungsverfolgung in Bioreaktoren mit Sensorpartikeln

Buntkiel, L.; Reinecke, S.; Hampel, U.

Abstract

The triaxial measurement of accelerations using sensor particles in bioreactors is essential for flow analysis. Due to the mechanical structure of the sensor particles, the accelerometer is not located in the center of the applied forces. Therefore, centrifugal and Euler acceleration superposes its measurements. Due to the high dynamics and, the high angular velocities that the sensor particle experiences in the reactor, this influence cannot be neglected despite the small size of the sensor particles and must be taken into account in the system mode

Keywords: Flow measurement; Flow follower; Bioreactor

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Permalink: https://www.hzdr.de/publications/Publ-37470


Giant THz nonlinearity in topological and trivial HgTe-based heterostructures: Data

Uaman Svetikova, T. A.; de Oliveira, T.; Pashkin, A.; Ponomaryov, A.; Berger, C.; Fuerst, L.; Bayer, F.; Novik, E.; Buhmann, H.; Molenkamp, L.; Helm, M.; Kiessling, T.; Winnerl, S.; Kovalev, S.; Astakhov, G.

Abstract

This upload represents the data used for publication <<Giant THz nonlinearity in topological and trivial HgTe-based heterostructures>> including datasets, images and programming code.

1. Raw_data.rar contains raw data files obtained during transport measurements, two-colour pump-probe experiments(FELBE) and third harmonic generation experiments.

2. Drude_fit.rar contains the result of fitting the complex change in conductivity with Drude fit.

3. Band_structure_calculation.rar contains the result of the fermi energy and dispersion calculations based on kp-method.

4. Theoretical_model_calculation.rar contains the code of the program for the theoretical model for THG and fitting it with experimental data and its result

5. Presentation_Sample_QC0600.pptx contains the information about used sample.

Keywords: topological insulators; third harmonic generation; HgTe

Involved research facilities

  • T-ELBE
  • F-ELBE

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Permalink: https://www.hzdr.de/publications/Publ-37468


Leveraging Ligand and Composition Effects: Morphology-Tailorable Pt–Bi Bimetallic Aerogels for Enhanced (Photo-)Electrocatalysis

Xue, G.; Li, Y.; Du, R.; Wang, J.; Hübner, R.; Gao, M.; Hu, Y.

Abstract

Metal aerogels (MAs) are emerging porous materials displaying unprecedented potential in catalysis, sensing, plasmonic technologies, etc. However, the lack of efficient regulation of their nano-building blocks (NBBs) remains a big hurdle that hampers the in-depth investigation and performance enhancement. Here, by harmonizing composition and ligand effects, Pt- and Bi-based single- and bimetallic aerogels bearing NBBs of controlled dimensions and shapes are obtained by facilely tuning the metal precursors and the applied ligands. Particularly, by further modulating the electronic and optic properties of the aerogels via adjusting the content of the catalytically active Pt component and the semiconducting Bi component, both the electrocatalytic and photoelectrocatalytic performance of the Pt–Bi aerogels can be manipulated. In this light, an impressive catalytic performance for electro-oxidation of methanol is acquired, marking a mass activity of 6.4-fold higher under UV irradiation than that for commercial Pt/C. This study not only sheds light on in situ manipulating NBBs of MAs, but also puts forward guidelines for crafting high-performance MAs-based electrocatalysts and photoelectrocatalysts toward energy-related electrochemical processes.

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-37466


Radiolabeling of Micro-/Nanoplastics via In-Diffusion

Stricker, A.; Hilpmann, S.; Mansel, A.; Franke, K.; Schymura, S.

Abstract

Micro- and nanoplastics are emerging pollutants with a concerning persistence in the
environment. Research into their environmental impact requires addressing challenges related to
sensitively and selectively detecting them in complex ecological media. One solution with great
potential for alleviating these issues is using radiolabeling strategies. Here, we report the successful
introduction of a 64Cu radiotracer into common microplastics, namely polyethylene, polyethylene
terephthalate, polystyrene, polyamide, and polyvinylidene dichloride, which allows the sensitive
detection of mere nanograms of substance. Utilizing a Hansen Solubility Parameter screening, we
developed a swelling and in-diffusion process for tetraphenylporphyrin-complexed 64Cu, which
permits one-pot labeling of polymer particles

Keywords: microplastics; radiolabeling; Hansen solubility parameters; In-Diffusion

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37465


Nanomagnetism and strain effects in magnetoelectric antiferromagnet Cr2O3

Pylypovskyi, O.

Abstract

Concepts of the future of spintronics are often based on antiferromagnetic materials because of their attraction for low-energy operating and high-speed devices. However, an absence of significant net magnetization also results in challenges for manipulation and readout of the magnetic state. In this respect, room-temperature magnetoelectric easy-axis Cr2O3 is of special interest [1].

In a single-crystal Cr2O3 domain wall is a metastable excitation, which can be induced by a magnetoelectric poling procedure and being pinned by specially designed surface defects. In contrast, thin films usually have a granular structure with significant amount of crystal defects acting as pinning sites for domain walls. Concentration and structure of the defects can be controlled by the film fabrication procedure, keeping the net magnetoelectric effect present for the sample [2]. Furthermore, low-defect films grown at sapphire can be persistently strained [3]. An out-of-plane magnetic moment formed by one of antiferromagnetic sublattices at the c-plane of Cr2O3 provides a possibility for the Hall magnetometry detecting magnetization direction by the Hall resistance measured in Pt capping layer [4].

The Neel temperature of bulk Cr2O3 of 35C is the strong limiting technological factor for practical applications. There are theoretical and experimental demonstrations that the compressive strain induced by doping or procedure of growing at sapphire substrate leads to the substantial broadening of the antiferromagnetic phase by temperature increasing the Neel temperature above 100C [3,5]. Furthermore, strained thin films can possess an inhomogeneous strain along the thickness, enabling net magnetization of flexomagnetic origin and vertical gradient of the Neel temperature. The latter provides a local flexomagnetic response which is controlled by the direction of the antiferromagnetic order parameter and scales with the sample’s temperature [3].

We anticipate that Cr2O3 provides a flexible material platform for the fundamental and applied physics by demonstration of unique crystal-symmetry-assisted effects.

Keywords: Cr2O3; magnetoelectricity; flexoeffects

  • Invited lecture (Conferences)
    IEEE NAP 2023, 10.-15.09.2023, Bratislava, Solvakia

Permalink: https://www.hzdr.de/publications/Publ-37464


Analysis of the influence of swirling flow on the boiling heat transfer characteristics of two-phase flow

Wu, W.; Ding, W.; Hampel, U.; Sun, B.

Abstract

The Eulerian-Eulerian (EE) simulation approach + GENeralized TwO Phase (GENTOP) concept and two-fluid three-flow field with droplet were used to simulate the heat and mass transfer. Analysis encompassed the examination of steam and liquid phase distributions, as well as flow pattern transitions. Heat transfer enhancements were quantified using a comprehensive heat transfer factor. The disturbance intensity of the secondary flow was characterized by the absolute vortex flux. Results revealed a correlation between the intensity of the secondary flow and axial length, indicative of progressive fluid disturbance enhancement. Additionally, the maximal motion of the steam phase vortex was observed both near the wall and channel center. The EE+GENTOP concept exhibited superior capability in reproducing multi-scale flow including small-scale dispersed bubbles and large-scale continuous steam (coalescence and break-up). For investigations into the entrainment and deposition of liquid droplets in annular flow, the selection of a two-fluid three-flow field with the droplet model is recommended.

Keywords: swirling flow; secondary flow; heat transfer enhancement; two-phase flow

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  • Secondary publication expected from 16.12.2024

Permalink: https://www.hzdr.de/publications/Publ-37463


Coordination chemistry of the early actinides in various oxidation states (+III to +V) with benzamidinate ligand

Hong, B.; Kaden, P.; Näder, A.; Gericke, R.; Patzschke, M.; Schmidt, M.; Stumpf, T.; März, J.

Abstract

Compared to the lanthanides, which primarily exhibit the oxidation state +III, the early actinides up to plutonium can display a diverse range of oxidation states spanning from +I to +VII. In the context of exploring oxidation states and covalency of actinides complexes, it would be intriguing and valuable to compare compounds that share the same molecular scaffold but differ in their oxidation states. Amidinate ligands have been widely studied in the field of coordination chemistry due to their excellent capability to stabilize transition metal complexes in various oxidation states, including some early actinide metal complexes. Thus, N,N'-diisopropylbenzamidinate (iPr2BA) was selected as an appropriate model N-donor ligand for the current study. Our goal was to test the ligand’s ability to stabilize actinides in various oxidation states as well as its synthetic flexibility.
In order to gain insight into the bonding trends and electronic structures of each oxidation state, series of tetravalent actinide tris-iPr2BA chloride complexes [AnIVCl(iPr2BA)3] (An = Th, U, Np) were synthesized via salt metathesis, followed by subsequent synthetic transformations to obtain (pseudo)halide congeners and complexes in the +III and +V oxidation states. The synthesized complexes were analyzed by single crystal X-ray diffraction (SC-XRD) to examine their molecular structures in solid state. Furthermore, the combination of paramagnetic NMR experiments in solution and quantum chemical calculations enabled the comparison of the overall degree of covalency between different oxidation states within the same tris-amidinate complex scaffold.

Keywords: Actinides; Lanthanides; Coordination chemistry; SC-XRD; NMR; amidinate; N-donor ligands; paramagnetism

  • Lecture (Conference)
    The 11th International Conference on f Elements (ICFE-11), 22.-26.08.2023, Strasbourg, France

Permalink: https://www.hzdr.de/publications/Publ-37462


A direct numerical simulation study to elucidate the enhancement of heat transfer for nucleate boiling on surfaces with micro-pillars

Zhang, J.; Rafique, M.; Ding, W.; Bolotnov, I. A.; Hampel, U.

Abstract

Recent experimental studies have demonstrated great potential of surface engineering in enhancing nucleate boiling heat transfer performance. However, the underlying mechanism remains unclear, especially the role of microlayer evaporation underneath bubbles. In this work, we investigate the heat transfer from microlayer evaporation underneath a growing bubble on micro-pillar arrayed surfaces using Direct Numerical Simulations (DNS). The evolution of the microlayer is reproduced in the DNS by considering a bubble growth driven by the local temperature gradient. The effects of micro-pillar structures on the microlayer profile and the heat transfer performance are systematically studied and analyzed. Our simulation results reveal three distinct microlayer morphologies related to micro-pillar structures: the undisturbed microlayer, the disturbed microlayer, and the disrupted microlayer. It can be further generalized as the greater the spacing and height of the micro-pillars, the more disrupted the microlayer becomes. Due to the reduction of microlayer thickness, more disruption means higher microlayer heat transfer coefficient. However, this accelerates microlayer depletion and thus reduces the overall heat transfer potential from microlayer evaporation during its life cycle in nucleate boiling. Based on these findings, a strategy is revealed for the design of micro-pillar arrayed surfaces to achieve optimal heat transfer performance of the microlayer.

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  • Secondary publication expected from 26.07.2024

Permalink: https://www.hzdr.de/publications/Publ-37461


Bispidine Chelators for Radiopharmaceutical Applications with Lanthanide, Actinide and Main Group Metal Ions

Kopp, I.; Cieslik, P.; Anger, K.; Josephy, T.; Neupert, L.; Velmurugan, G.; Gast, M.; Wadepohl, H.; Brühlmann, S. A.; Walther, M.; Kopka, K.; Bachmann, M.; Stephan, H.; Kubeil, M.; Comba, P.

Abstract

Octa- and specifically nonadentate ligands with a bispidine scaffold (3,7-diazabicyclo[3.3.1]nonane) are known to be efficiently coordinated to a range of metal ions of
interest in radiopharmaceutical chemistry and lead to exceedingly stable and inert complexes. The nonadentate bispidine L2 (with a tridentate bipyridine acetate appended to N3 and a
picolinate at N7) has been shown before to be an ideal chelator for 111In3+, 177Lu3+ and 225Ac3+, nuclides of interest for diagnosis and therapy, and a proof-of-principle study with an SSTR2-specific octreotate has shown potential for theranostic applications. We now have extended these studies in two directions. Firstly, we present the ligand derivative L3, where the bipyridine acetate is substituted with terpyridine, a softer donor for metal ions with a preference for more covalency. L3 did not fulfill the hopes because complexation is much less efficient: while for Bi3+ and Pb2+ the ligand is an excellent chelator with similar properties to L2, Lu3+ and La3+ show very slow and inefficient complexation with L3 in contrast to L2, and 225Ac3+ is not fully coordinated, even at an elevated temperature (92% radiochemical yield (RCY) at 80 °C, 60 min, [L3] = 10-4 M). These observations have led to a hypothesis for the complexation pathway that is in line with all experimental data and supported by a preliminary DFT analysis, which is of importance for the design of further optimized bispidine chelators. Secondly, the coordination chemistry of L2 has been extended to Bi3+, La3+ and Pb2+, including solid state and solution structural work, complex stabilities, radiolabeling and radiostability studies. All complexes of this ligand (La3+, Ac3+, Lu3+, Bi3+, In3+, Pb2+), including nuclides for targeted alpha therapy (TAT), single photon emission computed tomography (SPECT), and positron emission tomography (PET) are formed efficiently at physiological conditions, i.e., suitable for the labeling of delicate biological vectors such as antibodies, and the complexes are very stable and inert. Importantly, for TAT with 225Ac, the daughter nuclides 213Bi and 209Pb also form stable complexes, and this is of importance to reduce damage to healthy tissue.

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37460


Richtungsaufgelöste Messung von Beschleunigungen mit Sensorpartikeln in industriellen Prozessbehältern

Buntkiel, L.; Reinecke, S.; Hampel, U.

Abstract

Prozesse wie sie in großen Behältern, etwa in Biogasfermentern, Biorektoren oder Belebtschlammbecken ablaufen, haben ein hohes Optimierungspotenzial hinsichtlich der Energieeffizienz der Vermischung. Schlechtes Mischen im Behälter führt zu zu Totzonen und einer ineffizienten Nutzung der eingetragenen Energie. Messungen in diesen Behältern sind aufgrund des opaken Fluids und der Größe und Beschaffenheit der Behälter mit konventioneller Messtechnik nur an lokalen Messstellen möglich. Um ortsaufgelöst Prozessparameter und die Strömung zu messen, wurde am HZDR das Konzept instrumentierter, strömungsfolgender Sensorpartikel entwickelt. Strömungsfolgende Sensoren werden derzeit von einigen Gruppen weltweit entwickelt. Ausgestattet sind sie mit mindestens einem Druck– und einem Temperatursensor. Auswerteschwerpunkt ist die vertikale Position (Tauchtiefe) im Behälter basierend auf einer Messung des hydrostatischen Drucks. Analysiert werden typischerweise vertikale Aufenthaltswahrscheinlichkeiten, vertikale Geschwindigkeitsprofile, Zirkulationszeiten, aus denen ein Zusammenhang mit der globalen Mischzeit des Reaktors hergestellt wird, sowie ein automatisiertes Einteilen des Behälters in vertikale Mischbereiche als neueste Analysemethode.

Keywords: Sensorpartikel; Strömungsmessung; Kalman-Filter; Sensorfusion; Inertiale Navigation

  • Open Access Logo Contribution to proceedings
    16. Dresdner Sensor-Symposium 2022, 05.-07.12.2022, Dresden, Deutschland, Wunstorf: AMA Service GmbH, 978-3-9819376-7-1, 51-56
    DOI: 10.5162/16dss2022/6.3

Permalink: https://www.hzdr.de/publications/Publ-37458


Oxygen vacancy clusters in bulk cerium oxide and the impact of gold atoms

Longo, A.; Mirone, A.; de Clermont Gallerande, E.; Sahle, C. J.; Casaletto, M. P.; Amidani, L.; Theofanidis, S.; Giannici, F.

Abstract

We demonstrate the formation of oxygen vacancy clusters in the bulk of ceria and Au/ceria catalysts upon reduction with CO, and their interplay with 4f and 5d orbital hybridization of Ce3+, through state-of-the-art in situ synchrotron characterization and ab initio simulations. In situ X-ray Raman spectroscopy (XRS) at the oxygen K- and cerium N4,5-edges, coupled with in situ X-ray diffraction (XRD), are explained by ab initio density functional theory (DFT) and multiplet calculations. In particular, XRS at cerium N4,5-edges is analyzed here for the first time, unvealing new details on the formation of Ce3+ in the bulk, a key feature of XRS. The combined multiplet analysis at the N4,5-edge allows to detect the formation of Ce3+ also in Au/ceria upon treatment at low temperature. Since bulk sensitivity is a key feature of XRS, the modifications registered at the O K-edge reflect the rearrangement of the oxygen sublattice. DFT calculations are used to simulate the effects of vacancy ordering in the bulk, and allow us to fully explain the modification of the O K-edge involving the hybridization of the Ce 4f and 5d states. According to simulations, these changes can be connected to the oxygen vacancy clustering in the bulk of ceria.

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  • ORA-06502: PL/SQL: numerischer oder Wertefehler: Zeichenfolgenpuffer zu klein

Room-temperature extended short-wave infrared GeSn photodetectors realized by ion beam techniques

Wen, S.; Shaikh, M. S.; Steuer, O.; Prucnal, S.; Grenzer, J.; Hübner, R.; Turek, M.; Pyszniak, K.; Reiter, S.; Fischer, I. A.; Georgiev, Y.; Helm, M.; Wu, S.; Luo, J.-W.; Zhou, S.; Berencen, Y.

Abstract

GeSn alloys hold great promise as high-performance, low-cost, near- and short-wavelength infrared photodetectors with the potential to replace the relatively expensive and currently market-dominant InGaAs- and InSb-based photodetectors. In this Letter, we demonstrate room-temperature GeSn pn photodetectors fabricated by a complementary metal-oxide-semiconductor compatible process, involving Sn and P ion implantation and flash-lamp annealing prior to device fabrication. The fabrication process enables the alloying of Ge with Sn at concentrations up to 4.5% while maintaining the high-quality single-crystalline structure of the material. This allows us to create Ge0.955Sn0.045 pn photodetec-tors with a low dark current density of 12.8 mA/cm2 and a relatively high extended responsivity of 0.56 A/W at 1.71 l m. These results pave the way for the implementation of a cost-effective, scalable, and CMOS-compatible short-wavelength infrared detector technology.

Keywords: Semiconductors; Photodetectors; GeSn; Implantation; Flash-lamp annealing

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Permalink: https://www.hzdr.de/publications/Publ-37456


Study of QED singular properties for variable gyromagnetic ratio g≃2

Rafelski, J.; Evans, S.; Labun, L.

Abstract

Using the external field method, {\it i.e.\/} evaluating the effective action $V_{\mathrm{eff}}$ for an arbitrarily strong constant and homogeneous field, we explore nonperturbative properties of QED allowing arbitrary gyromagnetic ratio $g$. We find a cusp at $g = 2$ in: a) The QED $b_0$-renormalization group coefficient, and in the infinite wavelength limit in b) a subclass containing the pseudoscalar ${\cal P}^{2n}= (\vec E\cdot\vec B)^{2n} $ of light-light scattering coefficients. Properties of $b_0$ imply for certain domains of $g$ asymptotic freedom in an Abelian theory.

Keywords: Schwinger effect; vacuum stability; magnetic moment

Permalink: https://www.hzdr.de/publications/Publ-37455


Axion search via Coulomb-assisted quantum vacuum birefringence

Evans, S.; Schützhold, R.

Abstract

We study the impact of axions or axion-like particles on birefringent (i.e., polarization changing) scattering of x-ray photons at the Coulomb field of nuclei superimposed by optical lasers of ultra-high intensity. Applying the specifications of the Helmholtz International Beamline for Extreme Fields (HIBEF), we find that this set-up can be more sensitive than previous experiments such as PVLAS in a large domain of parameter space. Furthermore, by changing the pump and probe laser orientations and frequencies, one can scan different axion masses.

Permalink: https://www.hzdr.de/publications/Publ-37454


Improving Euler-Heisenberg-Schwinger Effective Action with Dressed Photons

Evans, S.; Rafelski, J.

Abstract

We implement a longstanding proposal by Weisskopf to apply virtual polarization corrections to
the in/out external fields in study of the Euler-Heisenberg-Schwinger effective action. Our approach
requires distinguishing the electromagnetic and polarization fields based on mathematical tools
developed by Bia lynicki-Birula, originally for the Born-Infeld action. Our solution is expressed
as a differential equation where the one-loop effective action serves as input. As a first result of
our approach, we recover the higher-order one-cut reducible loop diagrams discovered by Gies and
Karbstein.

Keywords: Euler–Heisenberg–Schwinger (EHS); non-perturbative vac-uum structure; quantum electrodynamics (QED)

Permalink: https://www.hzdr.de/publications/Publ-37453


Lane formation of colloidal particles driven in parallel by gravity

Isele, M.; Hofmann, K.; Erbe, A.; Leiderer, P.; Nielaba, P.

Abstract

We investigate the lane formation in nonequilibrium systems of colloidal particles moving in
parallel that are driven by the force of gravity. For this setup, an experimental implementation of a channel on a slope can be conceptualized. We employ the Brownian dynamics algorithm and confine the repulsive particles with hard walls based on the solution of the Smoluchowski equation in the half space. A difference of the driving force acting on the colloids could be achieved by using two spherical particle types with differing diameters but equal mass density. Firstly, we investigate how a difference in the channel slope affects the lane formation of the systems, after which we analyze the lanes that formed. We found that the large particles push the small particles to the walls, resulting in exclusively small particle lanes at the walls. This contrasts the equilibrium state, where depletion forces push the larger particles to the walls. Additionally, we have a closer look at the mechanisms by which the lanes form. Finally, we found system parameter values that foster lane formation to lay the foundation for an experimental realization of our proposed setup. To round this off, we give an exemplary calculation of the slope angle needed to get the experimental system into a state of lane order. With the examination of lane order in systems that are driven in parallel, we hope to deepen our understanding of nonequilibrium order phenomena.

Keywords: soft matter; colloidal model systems

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Permalink: https://www.hzdr.de/publications/Publ-37452


Giant THz nonlinearity in topological and trivial HgTe-based heterostructures

Uaman Svetikova, T. A.; de Oliveira, T.; Pashkin, A.; Ponomaryov, O.; Berger, C.; Fuerst, L.; Bayer, F.; Novik, E.; Buhmann, H.; Molenkamp, L.; Helm, M.; Kiessling, T.; Winnerl, S.; Kovalev, S.; Astakhov, G.

Abstract

Nonlinear phenomena in the THz spectral domain are important for the understanding of optoelectronic properties of quantum systems and provide a basis for modern information technologies. Here, we report a giant THz nonlinearity in high-mobility 2D topological insulators based on HgTe quantum wells, which manifests itself in a highly efficient third harmonic generation. We observe a third harmonic THz susceptibility several times higher than in bare graphene and many orders of magnitude higher than in trivial quantum well structures based on other materials. To explain the strong nonlinearity of HgTe-based heterostructures at the THz frequencies, we consider the acceleration of free carriers with high mobility and variable dispersion. This acceleration model, for which the non-parabolicity of the band dispersion is key, in combination with independently measured scattering time and conductivity is in good agreement with our experimental data in a wide temperature range for THz fields below the saturation. Our approach provides a route to material engineering for THz applications based on frequency conversion.

Keywords: topological insulators; HgTe; third harmonic generation

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Permalink: https://www.hzdr.de/publications/Publ-37451


Helmholtz Open Science Forum “Research Evaluation, Reputation Systems, and Openness”

Genderjahn, S.; Bertelmann, R.; Ferguson, L. M.; Graf Zu Castell-Rüdenhausen, W.; Dransch, D.; Juckeland, G.; Kiesselbach, M.; Köhler, M.; Rank, S.; Rohmann, J. L.; Upmeier, A.; Wiesenfeldt, S.

Abstract

On May 9, 2023, the Helmholtz Open Science Office organized the Forum "Research Evaluation, Reputation Systems, and Openness". On this occasion, experts from Helmholtz and the scientific community presented current developments in the field of research evaluation and reflected on the connection between reputation systems and openness. The event focused on three main topics: 1) Development of Helmholtz quality indicators for data and software products, 2) 10 years Declaration on Research Assessment (DORA) and 3) Coalition for Advancing Research Assessment (CoARA). A central subject in the discussion and presentations was the issue of the use and definitions of indicators which foster Open Science. The discussion centered on what appropriate incentives look like in order to make research evaluation fair and appreciative. Furthermore, the relevance of these questions from the perspective of early-career scientists was highlighted.

Permalink: https://www.hzdr.de/publications/Publ-37450


Longitudinal cerebral perfusion in presymptomatic genetic frontotemporal dementia: GENFI results

Pasternak, M.; Mirza, S.; Luciw, N.; Mutsaerts, H.; Petr, J.; Thomas, D.; Cash, D.; Bocchetta, M.; Tartaglia, C.; Mitchell, S.; Black, S.; Freedman, M.; Tang-Wai, D.; Rogaeva, E.; Russell, L.; Bouzigues, A.; van Swieten, J.; Jiskoot, L.; Seelaar, H.; Laforce Jr., R.; Tiraboschi, P.; Borroni, B.; Galimberti, D.; Rowe, J.; Graff, C.; Finger, E.; Sandro, S.; de Mendonça, A.; Butler, C.; Gerhard, A.; Sánchez-Valle, R.; Moreno, F.; Synofzik, M.; Vandenberghe, R.; Ducharme, S.; Levin, J.; Otto, M.; Santana, I.; Strafella, A.; Macintosh, B.; Rohrer, J.; Masellis, M.

Abstract

Genetic frontotemporal dementia is most commonly attributable to mutations in the C9orf72, GRN, or MAPT genes. The disease has near-complete penetrance, making presymptomatic carriers an ideal population for ascertaining the earliest changes in disease progression and the identification of suitable biomarkers for designing therapeutic trials when minimal neuronal loss has occurred. Cerebral perfusion, as measured by arterial spin labelling (ASL) MRI, has shown promise in being one such biomarker. However, longitudinal profiles of change in perfusion over time in presymptomatic carriers across all three genetic subgroups are lacking.
Using data from the multicenter GENetic Frontotemporal dementia Initiative, we investigated longitudinal profiles of cerebral perfusion using ASL-MRI in C9orf72 (n = 42), GRN (n = 70), and MAPT (n = 31) presymptomatic mutation carriers and non-carrier controls (n = 158). ASL and T1w scans were processed with the ExploreASL pipeline to produce partial volume corrected perfusion images, which were parcellated to extract mean perfusion values from whole brain grey matter and regions defined by the second version of the automated anatomical atlas (AAL2). Linear mixed effects models were used to assess longitudinal perfusion change.
Mutation carrier groups and non-carriers were statistically indistinguishable by baseline demographic and clinical measures. Decline in whole brain grey matter perfusion over time was more pronounced in all three carrier subgroups relative to controls, with changes most pronounced in GRN, followed by C9orf72 and MAPT variants. Additionally, GRN and MAPT groups featured global grey matter hypoperfusion relative to non-carrier controls as early as one year after baseline measurement, with C9orf72 featuring significant hypoperfusion after two years. Region of interest analysis demonstrated that each genetic subgroup had its own regional profile in terms of longitudinal perfusion decline. Perfusion decline in C9orf72 was localized around the frontal lobe and subcortical structures with a slight right-hemispheric bias. GRN featured a more widespread perfusion decline, with notable asymmetry featuring a stronger left hemisphere involvement. Significant decline in perfusion in MAPT was limited to the thalamus, which was a region that was significant in all three mutation carrier groups. Cerebral blood flow relative to baseline measurements had declined to a greater extent in converter individuals versus presymptomatic carriers who were past their expected year of disease onset within specific frontal regions of the brain.
These results provide additional evidence that cerebral perfusion is a potential biomarker for assessment of genetic FTD and its genetic subgroups at the prodromal stage of the disease.

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Permalink: https://www.hzdr.de/publications/Publ-37449


Hydrodynamics in a Bubble Column – Part 1: Two-Phase Flow

Sommer, A.-E.; Draw, M.; Wang, L.; Schmidtpeter, J.; Hessenkemper, H.; Gatter, J.; Nam, H.; Eckert, K.; Rzehak, R.

Abstract

Multiphase computational fluid dynamics (CFD) simulation is a useful tool to study the hydrodynamics in a bubble column if
appropriate closure models are known. Systematic assessment of different models is an ongoing venture that benefits from
improved validation data. The present study accumulates a database on two-phase flow experiments in a bubble column.
This is achieved by using a combination of particle image velocimetry and shadowgraphy to measure the liquid velocity field
and gas dispersion properties simultaneously. This methodology is applied for different needle diameters and gas flow rates.
The experimental data are compared with CFD simulations which show good predictions. A systematic investigation of the
three-phase flow in the bubble column will appear as a sequel.

Keywords: Closure relations; Euler-Euler two-fluid model; Particle image velocimetry; Shadowgraphy; Two-phase bubble column

Permalink: https://www.hzdr.de/publications/Publ-37448


Data publication: Exploring Hydrophilic PD-L1 Radiotracers Utilizing Phosphonic Acids: Insights Into Unforeseen Pharmacokinetics

Krutzek, F.; Donat, C.; Stadlbauer, S.

Abstract

Bei diesem Datensatz handelt es sich um die chemische Charakterisierung der Verbindungen, die in-vitro- und in-vivo-Daten.

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  • PET-Center

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Permalink: https://www.hzdr.de/publications/Publ-37447


Exploring Hydrophilic PD-L1 Radiotracers Utilizing Phosphonic Acids: Insights Into Unforeseen Pharmacokinetics

Krutzek, F.; Donat, C.; Stadlbauer, S.

Abstract

Immune checkpoint inhibitor therapy targeting the PD-1/PD-L1 axis in cancer patients holds promise as an oncological treatment. However, the number of non-responders remains high. Consequently, clinicians need a diagnostic tool to predict treatment outcomes. PET imaging can play an important role in supporting therapy decisions by offering whole-body scan while quantitatively assessing PD-L1 expression. In multi-step organic synthesis, four PD-L1 radiolig-ands containing a linker-chelator system for radiometallation, along with three hydrophilizing units – one sulfonic acid and two phosphonic acids – were synthesized. After labeling with 64Cu, log D7.4 values of below –3.03 were determined and proteolytic stability studies were conducted confirming stabilities over 94% after 48 hours. Binding affinities studies were conducted using two different binding assays revealing high affinities up 13 nM. µPET/CT imaging was performed in tumor-bearing mice to investigate PD-L1 specific tumor uptake and the pharmacokinetic profile. The µPET images revealed an unexpected in vivo behavior, including low tumor uptake in PD-L1 positive tumors, high liver uptake, and accumulation in bone/bone marrow/joints. These effects were attributed to Ca2+-affinity and/or binding to macrophages. Despite phosphonic acids offering a high degree of water-solubility, their incorporation must be carefully considered to avoid ex-acerbating the radioligands’ pharmacokinetic behaviors.

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  • PET-Center

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Permalink: https://www.hzdr.de/publications/Publ-37446


Reduction of the electron beam divergence of laser wakefield-accelerators by integrated plamsa lens

Chang, Y.-Y.; Couperus Cabadağ, J. P.; Debus, A.; Ghaith, A.; La Berge, M.; Pausch, R.; Schöbel, S.; Ufer, P.; Schramm, U.; Irman, A.

Abstract

We report on electron beam collimation using a passive plasma lens, integrated directly and conveniently into a laser wakefield accelerator stage operating in the high charge regime. The lens is created by reshaping the gas density profile of a super-sonic jet at the beam's exit side through an obstacle mounted above the jet. It reduces the beam's divergence by a factor of two to below 1 mrad (root-mean-square), while preserving the total charge of 170 pC and maintaining the energy spread. The resulting spectral-charge density, here defined as the charge per energy bandwidth and emission angle, of up to 7 pC/(MeV·mrad) played a key role in the recent experimental demonstration of free-electron lasing. The presented simple and robust gas shaping technique holds the potential to generate specific density profiles, essential for the application of adiabatic focusing or staging of accelerators.

Keywords: LWFA; Plasma Lens; PIConGPU

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  • Draco

Permalink: https://www.hzdr.de/publications/Publ-37445


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