Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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43543 Publications

X-ray computed tomography for treatment planning: current status and innovations

Peters, N.; Wohlfahrt, P.; Richter, C.

Abstract

X-ray computed tomography (CT) is the clinical standard for treatment planning in particle therapy. In this chapter, the basic principles of this state-of-the-art image modality will be described, as well as strategies to account for uncertainties of the conversion from CT number to ion stopping power.

Involved research facilities

  • OncoRay
  • Book chapter
    in: Imaging in Particle Therapy: Current practice and future trends, Great Britain: IOP Publishing, 2024, 978-075035119-5
    DOI: 10.1088/978-0-7503-5117-1ch4

Permalink: https://www.hzdr.de/publications/Publ-39505


Roles in FAIR data and their needs

van den Boogaart, K. G.; Rau, F.; Schaller, T.; Steinmeier, L.

Abstract

Different roles interact with research data in very different ways: Technicians, experimetal scientists, data analysts, modellers, supervisor, infrastructure providers, data stewards, toolchain providers, projekt managers, administrative personelle, liberians, publishers, NFDI contact persons, indexing service providers, external data user, programmers,...

Non of them can establish a effective research data management all on their own. Currently only very few of them have the training and the tools they need. In order to make FAIR data a widespread reality we will need to educate people, establish toolchains, provide long term services, and adopt standards.

FAIR research requires an organisation wide innovation and cultural transition. Large research organisations like the Helmholtz Centers and their institutes are particulary well suited to lead this transition.

This talk tries to give an overview of what is required: What are the tasks of the different roles, we need to think of? Where is money required? Who needs in-service-training on what? What toolchains need to be established? Who might provide these tools? What can HMC do? What does the center need to do? What are the potential benefits for the center, and how can they be realized?

The main aim of this contribution is to bring the different groups together, to establish an understanding of what is required from them and what they can expect from others.

Keywords: HMC; Research Data Management; Roles in Science

  • Lecture (Conference) (Online presentation)
    HMC Comference, 04.-06.11.2024, Virtual Event, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-39504


Accelerator-based THz sources for solid state spectroscopy – with two examples from exciton physics

Helm, M.

Abstract

I will introduce the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) with its two accelerator-based THz sources, FELBE and TELBE [1]. Then I will discuss two examples of nonlinear spectroscopy of excitons: the first one is the observation of the Autler-Townes splitting of an intra-excitonic 1s-2p transition in InGaAs quantum wells, an experiment more than a decade old, but still one of my favorites [2]. The second deals with the very recent observation of the THz induced photodetachment of trions in the 2D material MoSe2, i.e. the conversion of a trion (a charged exciton) into an exciton plus an electron [3]. Finally I will discuss the shortcomings of our present THz facilities, leading to the ideas for a successor facility, the Dresden Advanced Light Infrastructure DALI.

[1] M. Helm et al., Eur. Phys. J. Plus 138, 158 (2023).
[2] M. Wagner et al., Phys. Rev. Lett. 105, 167401 (2010); M. Teich et al., New J. Phys. 15, 065007 (2013); M. Teich et al., Phys. Rev. B 89, 115311 (2014).
[3] T. Venanzi et al., Nature Photonics, accepted for publication (2024).

Keywords: terahertz; thz; free electron laser; 2d materials; trions; excitons

Involved research facilities

  • F-ELBE
  • Lecture (others)
    Seminarvortrag Materials Department ETH Zürich, 26.08.2024, Zürich, Switzerland

Permalink: https://www.hzdr.de/publications/Publ-39502


A personal journey through four decades of THz sources, or how I didn’t invent the QCL

Helm, M.

Abstract

A personal journey through four decades of THz sources, or how I didn’t invent the QCL

Keywords: quantum cascade laser; THz sources

Involved research facilities

  • F-ELBE
  • Invited lecture (Conferences)
    IQCLS 2024 – 30 years of QCLs, 22.-24.08.2024, Zürich, Switzerland

Permalink: https://www.hzdr.de/publications/Publ-39501


ESFR-SIMPLE project: towards a ESFR-SMR design

Sciora, P.; Pantano, A.; Fridman, E.; Ponomarev, A.; Servell, P.; Gérardin, D.; Girardi, E.; Farges, B.; Mikityuk, K.; Rineiski, A.; Guidez, J.

Abstract

The ESFR SMART project, which took place from 2017 to 2022, made it possible to define a Sodium Fast Reactor (SFR) design based on past SFR experimental feedbacks and intended to meet post-Fukushima safety criteria. The main options retained are recalled here: a heterogeneous core with low sodium void reactivity effect and mitigation measures (corium transfer tubes), a sodiumresistant pit well, a metallic thick slab, and finally comprehensive set of measures allowing decay heat removal by natural convection. These studies were carried out during this project with a power of 3600 MWth which was the power of the initial EFR project initiated during the operation of Superphenix. The new ESFR-SIMPLE project, starting at the end of 2022, uses the same technical options but with reduced power. This choice could more easily allow the construction of a SFR prototype in Europe. Design options were chosen so that the reactor could be assembled off-site, then shipped by rail or ship to the construction site, which requires a vessel diameter limit of around 10 m. The paper presents the first design studies with a particular attention to the core and primary circuit sizing. The proposed ESFR-SMR results in a 360 MWth reactor. This power reduction may also allow some simplifications compared to the initial high-power concept, particularly in terms of passive evacuation of residual power. This last point will be more deeply investigated by the ESFRSIMPLE project in the next years

Keywords: ESFR SIMLE; ESFR SMART; SMR; core design

  • Contribution to proceedings
    International Congress on Advances in Nuclear Power Plants ICAPP 2024, 16.-19.06.2024, Las Vegas, USA

Permalink: https://www.hzdr.de/publications/Publ-39499


Core Design and Neutronic Analysis of The European Sodium Fast Reactor with Metallic Fuel

Jiménez-Carrascosa, A.; Mikityuk, K.; Stauff, N.; Karahan, A.; Fridman, E.; Ponomarev, A.

Abstract

The current ESFR (European Sodium Fast Reactor) design was proposed and in-depth evaluated in the frame of the past ESFR-SMART project. As a follow-up project, the ESFRSIMPLE has been launched with the aim of challenging the current commercial-size ESFR design in terms of safety features and economic performance. Among the new safety measures to be developed and assessed in ESFR-SIMPLE, the current oxide fuel ESFR design will be challenged by a modified version of the core with metallic fuel. This intends to conclude on what types of benefits can be obtained with high-density fuel, under similar safety and design constraints. In this paper, the designing approach for enabling the use of metallic fuel in the current ESFR core is described and a preliminary neutronic evaluation is carried out. The optimal configuration is established through the optimization of key neutronic parameters aiming at the potential reduction of the plutonium inventory. The resulting core configuration serves as a basis for further safety assessment analyses, which will provide insight into the advantages and drawbacks of the two types of fuels.

Keywords: Advanced reactors; Neutronics; Reactor Design; Next Generation Reactors

  • Contribution to proceedings
    International Conference on Nuclear Engineering ICONE2024, 04.-08.08.2024, Prague, Czech Republic

Permalink: https://www.hzdr.de/publications/Publ-39497


Insights into calculating Reference Discontinuity Factors with Serpent Monte Carlo code

Fridman, E.; Smith, J.; Kotlyar, D.

Abstract

This study explores the calculation of Reference Discontinuity Factors (RDFs) using the Serpent Monte Carlo code, focusing on the methodology and potential pitfalls. In two-step reactor analyses, consistently generated RDFs are crucial for aligning homogeneous nodal diffusion results with the reference heterogeneous transport solution. However, the Serpent internal diffusion solver, based on the Analytic Function Expansion Nodal (AFEN) method, may not be compatible with other nodal methods such as the Nodal Expansion Method (NEM). Additionally, the solver can suffer from instabilities, particularly in multi-group calculations, leading to erroneous RDFs. Despite these challenges, Serpent can generate the necessary raw data for RDF calculation, which can be accurately processed using external diffusion solvers. Two numerical examples - a 1D fuel-reflector model and a 2D SMR core model - illustrate the effects of consistent and inconsistent RDFs on simulation accuracy. The study emphasizes the importance of using compatible diffusion solvers and thoroughly assessing RDFs to avoid errors in reactor simulations.

Keywords: Few-group cross sections; discontinuity factors; Serpent; nodal methods; DYN3D; PARCS

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Permalink: https://www.hzdr.de/publications/Publ-39495


Electronic Structure and Topology in Gulf-edged Zigzag Graphene Nanoribbons

Liu, T.-J.; Arnold, F. M.; Ghasemifard, A.; Liu, Q.-L.; Golze, D.; Kuc, A. B.; Heine, T.

Abstract

With advanced synthetic techniques, a wide variety of well-defined graphene nano- ribbons (GNRs) can be produced with atomic precision. Hence, finding the relation between their structures and properties becomes important for the rational design of GNRs. In this work, we explore the complete chemical space of gulf-edged zigzag graphene nanoribbons (ZGNR-Gs), a subclass of zigzag GNRs in which the zigzag edges miss carbon atoms in a regular sequence. We demonstrate that the electronic properties of ZGNR-Gs depend on four structural parameters: ribbon width, gulf edge size, unit length, and gulf offset. Using tight-binding calculations and the Hubbard model, we find that all ZGNR-Gs are semiconductors with varying band gaps; there are no metals in this class of materials. Notably, when spin polarization is considered, most ZGNR- Gs exhibit antiferromagnetic behavior, with the spin moments and spin-induced band gap opening being stabilized by longer zigzag segments at the edges. Furthermore, we provide simple empirical rules that describe the Z2 topological invariant based on the aforementioned structural parameters. By analyzing the full chemical space of ZGNR- Gs, we offer insights into the design of GNRs with desired electronic, magnetic, and topological properties for nanoelectronic applications.

Permalink: https://www.hzdr.de/publications/Publ-39494


Data publication: Data science education in undergraduate physics: Lessons learned from a community of practice

Shah, K.; Butler, J.; Knaub, A. V.; Zenginoğlu, A.; Ratcliff, W.; Soltanieh-ha, M.

Abstract

This repository contains the modules developed as part of Data Science Education Community of Practice program of the American Physical Society. These open source modules are to be used for incorporating machine learning/data science concepts in undergraduate physics curriculum.

Keywords: Data science; Data analysis; Machine learning; Physics education research; Curriculum development

Related publications

  • Software in external data repository
    Publication year 2022
    Programming language: Python
    System requirements: Python environment or online Colab Notebook
    License: CC0-1.0 license (Link to license text)
    Hosted on https://github.com/GDS-Education-Community-of-Practice/DSECOP: Link to location

Permalink: https://www.hzdr.de/publications/Publ-39493


Data science education in undergraduate physics: Lessons learned from a community of practice

Shah, K.; Butler, J.; Knaub, A. V.; Zenginoğlu, A.; Ratcliff, W.; Soltanieh-ha, M.

Abstract

It is becoming increasingly important that physics educators equip their students with the skills to work with data effectively. However, many educators may lack the necessary training and expertise in data science to teach these skills. To address this gap, we created the Data Science Education Community of Practice (DSECOP), bringing together graduate students and physics educators from different institutions and backgrounds to share best practices and lessons learned from integrating data science into undergraduate physics education. In this article, we present insight and experiences from this community of practice, highlighting key strategies and challenges in incorporating data science into the introductory physics curriculum. Our goal is to provide guidance and inspiration to educators who seek to integrate data science into their teaching, helping to prepare the next generation of physicists for a data-driven world.

Keywords: Data science; Data analysis; Machine learning; Physics education research; Curriculum development

Related publications

  • Open Access Logo American Journal of Physics 92(2024)9, 655-662
    DOI: 10.1119/5.0203846
    arXiv: https://arxiv.org/abs/2403.00961

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Permalink: https://www.hzdr.de/publications/Publ-39492


Data publication: Advanced setup for in situ positron annihilation lifetime measurements under variable gas atmospheres and humidity: from cryogenic to high temperatures

Elsherif, A. G. A.; Hirschmann, E.; Butterling, M.; Hartmann, A.; Stach, D.; Findeisen, S.; Bon, V.; Kaskel, S.; Wagner, A.

Abstract

Positronium data of Maltodextrin at variable humidity levels.

Keywords: Positronium; gas adsorption and humidity; environmental conditions; porosity; metal-organic-frameworks

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Permalink: https://www.hzdr.de/publications/Publ-39491


Advanced setup for in situ positron annihilation lifetime measurements under variable gas atmospheres and humidity: from cryogenic to high temperatures

Elsherif, A. G. A.; Hirschmann, E.; Butterling, M.; Hartmann, A.; Stach, D.; Findeisen, S.; Bon, V.; Kaskel, S.; Wagner, A.

Abstract

We present a newly developed instrument for 22Na-based positron-annihilation lifetime spectroscopy (PALS), designed to facilitate the simultaneous control of temperature, gas atmosphere, and humidity in a single experimental system. The spectrometer operates within a temperature range of 50 K to 480 K and pressures from 10-6 mbar to 1.5 bar. It features a novel gas dosing chamber that allows in situ adsorption studies with gases such as, but not limited to, CO2, N2, Ar, O2, and their mixtures, with precise control over mixing ratios. Additionally, the device supports in situ humidity exposure, allowing for comprehensive studies of sample interactions with both humidity and humid gases. Fully automated, the system provides seamless data acquisition and environmental control, including pressure and temperature regulation. We demonstrate the instrument's capability to elucidate alterations in the free volume of maltodextrin under humidity exposure. Additionally, we illustrate the instrument's efficacy through case studies on CPO-27 metal-organic frameworks (MOFs), highlighting its versatility in analyzing adsorption phenomena across diverse gas adsorbates and temperatures. This state-of-the-art spectrometer stands as an indispensable tool for probing the physicochemical attributes of materials under varying conditions, providing pivotal insights into gas adsorption mechanisms and material dynamics.

Keywords: Positronium; gas adsorption and humidity; environmental conditions; porosity; metal-organic-frameworks

Related publications

Permalink: https://www.hzdr.de/publications/Publ-39490


Simulation data for "Cylindrical compression of thin wires by irradiation with a Joule-class short pulse laser"

Laso García, A.; Yang, L.; Huang, L.

Abstract

2D PIC of laser interaction with wire

Flash simulations for the shock formation and propagation

Involved research facilities

  • HIBEF

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Permalink: https://www.hzdr.de/publications/Publ-39489


Data publication: Ultrafast unidirectional spin Hall magnetoresistance driven by terahertz light field

Salikhov, R.; Ilyakov, I.; Reinold, A.; Deinert, J.-C.; de Oliveira, T.; Ponomaryov, O.; Prajapati, G. L.; Pilch, P.; Ghalgaoui, A.; Koch, M.; Faßbender, J.; Lindner, J.; Wang, Z.; Kovalev, S.
ContactPerson: Salikhov, Ruslan

Abstract

Raw data for the publication titled 'Ultrafast Unidirectional Spin Hall Magnetoresistance Driven by a Terahertz Light Field,' including the data presented in Figures 2 through 4.

Keywords: Terahertz spintronics; unidirectional spin-Hall magnetoresistance; terahertz second harmonic generation; magnetic heterostructures

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-39487


Data publication: Ab initio-simulated optical response of hot electrons in gold and ruthenium

Akhmetov, F.; Vorberger, J.; Milov, I.; Makhotkin, I.; Ackermann, M.

Abstract

All necessary scripts and input files to run the simulations as well as the relevant output files to make the figures.

Keywords: laser; gold; ruthenium; relaxation; energy transfer

Involved research facilities

  • Data Center

Related publications

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Permalink: https://www.hzdr.de/publications/Publ-39485


Interpretable foundation models as decryptor peering into Earth system

Li, C.; Hong, D.; Zhang, B.; Liao, T.; Yokoya, N.; Ghamisi, P.; Chen, M.; Wang, L.; Atli Benediktsson, J.; Chanussot, J.

Abstract

The processes of the Earth system drive interactions between energy, matter, and life, and a comprehensive understanding of their full evolutionary trajectory is critical for sustainable human development. Traditional modeling primarily relies on a set of theoretical equations to simulate dynamic process such as carbon-nitrogen cycle, solar radiation dynamics, and terrestrial ecosystem dynamics. Despite the extensive modeling experience of Earth scientists, the rapid advancement of Earth observation techniques has led to a significant increase in the volume of databases, with data accumulating daily, or even hourly. This has exacerbated the conflict between the capacity for data collection and utilization for big Earth data. Consequently, there is an urgent need to enhance the intelligent processing and analysis capabilities of big Earth data. At this critical juncture, the emergence of foundational models has revitalized the unique advantages of maximizing information retrieval and deriving insights from big Earth data. However, the mathematical principles underpinning their success are somewhat elusive, raising concerns about trustworthiness due to the lack of a clearly defined internal chain of reasoning and decision-making processes. Therefore, interpretable foundational models are crucial. They enhance our understanding and security of geoscientific applications, breakthrough performance limitations, and improve the controllability of their social impacts.

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Permalink: https://www.hzdr.de/publications/Publ-39482


From Density Response to Energy Functionals and Back: An ab initio perspective on Matter Under Extreme Conditions

Moldabekov, Z.; Vorberger, J.; Dornheim, T.

Abstract

Energy functionals serve as the basis for different models and methods in quantum and classical many-particle physics. Arguably, one of the most successful and widely used approaches in material science at both ambient and extreme conditions is density functional theory (DFT). Various flavors of DFT methods are being actively used to study material properties at extreme conditions, such as in warm dense matter, dense plasmas, and nuclear physics applications. In this review, we focus on the warm dense matter regime, which occurs in the core of giant planets and stellar atmospheres, and as a transient state in inertial confinement fusion experiments. We discuss the connection between linear density response functions and free energy functionals as well as the utility of the linear response formalism for the construction of advanced functionals. As a new result, we derive the stiffness theorem linking the change in the intrinsic free energy to the density response properties of electrons. We review and summarize recent works that assess various exchange-correlation (XC) functionals for an inhomogeneous electron gas that is perturbed by a harmonic external field and for warm dense hydrogen using exact path integral quantum Monte Carlo data as an unassailable benchmark. This constitutes a valuable guide for selecting an appropriate XC functional for DFT calculations in the context of investigating the inhomogeneous electronic structure of warm dense matter. We stress that correctly simulating the strongly perturbed electron gas necessitates the correct UEG limit of the XC and non-interacting free-energy functionals.

Keywords: density functional theory; warm dense matter; free energy functionals; linear density response functions; exchange-correlation functionals; path integral quantum Monte Carlo

Permalink: https://www.hzdr.de/publications/Publ-39481


Dynamic structure factor and dielectric properties of warm dense hydrogen form linear-response time-dependent density functional theory

Moldabekov, Z.

Abstract

Matter under extreme densities and temperatures—often referred to as warm dense matter (WDM)— is pivotal for a number of cutting-edge technological applications such as the discovery and synthesis of novel materials and hot-electron chemistry. A particularly important and timely application is given by inertial confinement fusion, where the fuel capsule has to traverse the WDM regime in a controlled way towards ignition. Unfortunately, the theoretical understanding of such extreme states is rendered notoriously difficult by the complex interplay of a variety of physical effects (Coulomb coupling, thermal excitations, quantum degeneracy, etc.). In practice, density functional theory (DFT) constitutes the workhorse of WDM theory. In this work we present our results on the dynamic structure factor and dynamic dielectric function of warm dense hydrogen computed from first principles using linear response time-dependent density functional theory. In addition, we discuss the relevance of the thermal exchange-correlation effects for the electronic structure in warm
dense hydrogen [1-4].

REFERENCES
[1] Z. Moldabekov, M. Lokamani, J. Vorberger, A. Cangi, T. Dornheim, “Non-empirical Mixing
Coefficient for Hybrid XC Functionals from Analysis of the XC Kernel”, J. Phys. Chem. Lett., 14,
1326-1333 (2023)
[2] Z. Moldabekov, M. Böhme, J. Vorberger, D. Blaschke, T. Dornheim, “Ab Initio Static Exchange–
Correlation Kernel across Jacob’s Ladder without Functional Derivatives”, J. Chem. Theory
Comput., 19, 1286-1299 (2023)
[3] Z. Moldabekov, M. Lokamani, J. Vorberger, A. Cangi, T. Dornheim, “Assessing the accuracy of
hybrid exchange-correlation functionals for the density response of warm dense electrons”, J.
Chem. Phys., 158, 094105 (2023)
[4] Z. Moldabekov, M. Pavanello, M. Böhme, J. Vorberger, T. Dornheim, “Linear-response time-
dependent density functional theory approach to warm dense matter with adiabatic exchange-
correlation kernels”, Phys. Rev. Research 5, 023089 (2023)
[5] Z. Moldabekov, S. Schwalbe, M. Böhme, J. Vorberger, X. Shao, M. Pavanello, F. Graziani, T.
Dornheim, “Bound state breaking and the importance of thermal exchange-correlation effects in warm
dense hydrogen”, J. Chem. Theory Comput., 20, 68-78 (2024)

Keywords: warm dense matter; density functional theory; thermal exchange-correlation effects; time-dependent density functional theory

  • Lecture (Conference)
    the 14th International Conference on High Energy Density Laboratory Astrophysics (HEDLA), 20.-24.05.2024, Tallahassee, Florida, USA

Permalink: https://www.hzdr.de/publications/Publ-39480


Signatures of Bound States Breaking in Warm Dense Hydrogen and the Relevance of Thermal Exchange-Correlation Effects

Moldabekov, Z.; Schwalbe, S.; Böhme, M.; Vorberger, J.; Dornheim, T.

Abstract

Hydrogen at extreme temperatures and pressures has significant relevance for cutting-edge technological applications, and its natural occurrence in astrophysical objects further underscores its importance. In this work, we develop a new framework to identify the breaking of bound states due to pressure ionization in bulk hydrogen [1]. Firstly, we show that the dimensionless reduced density gradient (RDG) is a valuable tool for detecting pressure-induced ionization in the medium. Secondly, the generalized RDG is proposed as an effective means for examining the interstitial electronic structure. Finally, our rigorous assessment of a variety of exchange-correlation (XC) functionals in density functional theory calculations for different density regions reveals the crucial role of thermal XC effects in accurately describing density gradients in high-energy density systems. Our exact path integral Monte-Carlo (PIMC) test set generated for this project is freely available online [2]. The insights gained from this research could also have implications for our understanding of astrophysical phenomena, such as white dwarf stars. Furthermore, this study is an addition to our current research on thermal effects in XC functionals, which we are exploring at various complexity levels [3-6].

References:

[1] Z. Moldabekov, S. Schwalbe, M. P. Böhme, J. Vorberger, X. Shao, M. Pavanello, F.
Graziani, T. Dornheim, Journal of Chemical Theory and Computation (in print) (2023).
DOI: 10.1021/acs.jctc.3c00934 ; arXiv:2308.07916.
[2] The data is available according to the FAIR principles on the bound state breaking BSB
GitLab Repository. 2023; https://gitlab.com/theonov13/bsb
[3] Z. Moldabekov, M. Lokamani, J. Vorberger, A. Cangi, and T. Dornheim, The Journal of
Physical Chemistry Letters 14 (5), 1326-1333 (2023).
[4] Z. Moldabekov, M. Lokamani, J. Vorberger, A. Cangi, T. Dornheim, J. Chem. Phys.
158, 094105 (2023).
[5] Z. Moldabekov, T.Dornheim, M. Böhme, J. Vorberger, A. Cangi, J. Chem. Phys. 155,
124116 (2021).
[6] Z. Moldabekov, M. Böhme, J. Vorberger, D. Blaschke, and T. Dornheim, Journal of
Chemical Theory and Computation 19, 1286-1299 (2023)

Keywords: Hydrogen at extreme temperatures and pressures; thermal exchange-correlation functionals; path integral Monte-Carlo; Density Functional Theory

  • Poster
    Current challenges in the physics of white dwarf stars, 25.-29.03.2024, Santa Fe, USA

Permalink: https://www.hzdr.de/publications/Publ-39479


Ultrafast Heating-Induced Suppression of d‑Band Dominance in the Electronic Excitation Spectrum of Cuprum

Moldabekov, Z.; Gawne, T. D.; Schwalbe, S.; Preston, T. R.; Vorberger, J.; Dornheim, T.

Abstract

The combination of isochoric heating of solids by free-electron lasers (FELs) and in situ diagnostics by X-ray Thomson scattering (XRTS) allows for measurements of material properties at warm dense matter (WDM) conditions relevant for astrophysics, inertial confinement fusion, and materials science. In the case of metals, the FEL beam pumps energy directly into electrons with the lattice structure of ions being nearly unaffected. This leads to a unique transient state that gives rise to a set of interesting physical effects, which can serve as a reliable testing platform for WDM theories. In this work, we present extensive linear-response time-dependent density functional theory (TDDFT) results for the electronic dynamic structure factor of isochorically heated copper with a face-centered cubic lattice. At ambient conditions, the plasmon is heavily damped due to the presence of d-band excitations, and its position is independent of the wavenumber. In contrast, the plasmon feature starts to dominate the excitation spectrum and has a Bohm–Gross-type plasmon dispersion for temperatures T ≥ 4 eV, where the quasi-free electrons in the interstitial region are in the WDM regime. In addition, we analyze the thermal changes in the d-band excitations and outline the possibility to use future XRTS measurements of isochorically heated copper as a controlled testbed for WDM theories.

Keywords: X-ray Thomson scattering; free-electron lasers; time-dependent density functional theory; warm dense matter

Involved research facilities

  • HIBEF

Permalink: https://www.hzdr.de/publications/Publ-39478


The role of dissimilatory iron reduction by a Desulfitobacterium isolate on the immobilization of technetium-99

Cardaio, I.; Müller, K.; Cherkouk, A.; Stumpf, T.; Mayordomo, N.

Abstract

Technetium (Tc) is the element 43 of the periodic table with an estimated number of 45 isotopes, being ⁹⁹Tc the most relevant. ⁹⁹Tc is a β⁻ emitter with a long half-life [(t(1/2) = 2.13 · 105 a)], a fission product of ²³⁵U and ²³⁹Pu and it can also originate from the decay chain of its metastable isomer ⁹⁹ᵐTc, a short-lived isotope [t(1/2) = 6,01 h]) [1]. Thus, the release of Tc in the environment is mainly due to reprocessing of spent nuclear fuel, nuclear energy production, nuclear weapon detonation and the wide use of ⁹⁹ᵐTc in radiodiagnostics [2]. Technetium oxidation states range from –I to +VII. The most common states in the environment are Tc(VII) and Tc(IV) in absence of stabilizing organic ligands. Under oxidizing conditions, technetium would rather occur as TcVII in the form of pertechnetate [Tc(VII)O₄⁻)], whereas Tc(IV) prevails under reducing conditions. The high solubility in aqueous phases and poor ability of interactions with mineral surfaces make Tc(VII)O₄⁻ a very hazardous anion. In contrast, Tc(IV) mobility in water is limited due to its reduced solubility and interactions with mineral surfaces, such as Fe(II) minerals [3; 4]. Deep geological repositories (DGRs) for the safe long-term storage of radiotoxic waste are conceptualized as multi-barrier systems based on (geo)technical and geologic layers [5]. Bentonite clay, as geotechnical barrier, is considered a good candidate to act as buffer material for the retention of radionuclides. The clay harbors indigenous microorganisms such as anaerobic bacteria, which, through their natural production of acidic metabolites, can alter the chemical conditions and the integrity of the materials present in the DGR [6]. Thus, the influence of bacteria and bacterial induced processes on Tc (im)mobilization needs to be understood in detail on a macroscopic and molecular level. In this work, we have studied the influence of Desulfitobacterium sp. G1-2, a novel isolate extracted from FEBEX bentonite, on Tc mobility [7]. The bacterium was grown in presence of Fe(III) citrate [8; 9]. During its growth, the formation of a white precipitate was observed. Raman microscopy and X-ray diffraction confirmed the identity of the precipitate as vivianite [(Fe(II)₃(PO₄)₂·8H₂O)] [10; 11]. The biogenic vivianite was extracted and applied to investigate the yield of Tc retention from the solution. It was shown that Tc removal by bio-vivianite reached 94% at pH(eq) ≈ 8.5 after seven days of interaction, it´s dependent on time and pH, and is due to the reduction of Tc(VII) to Tc(IV).

Keywords: Technetium; Microorganisms; Deep geologiocal repositories; Vivianite; Iron reduction

Involved research facilities

Related publications

  • Invited lecture (Conferences) (Online presentation)
    1st webinar of the Alliance’s Young Researchers, 19.09.2024, Online webinar, Germany

Permalink: https://www.hzdr.de/publications/Publ-39476


Excitation signatures of isochorically heated electrons in solids at finite wave number explored from first principles

Moldabekov, Z.; Gawne, T.; Schwalbe, S.; Preston, T.; Vorberger, J.; Dornheim, T.

Abstract

Ultrafast heating of solids with modern x-ray free electron lasers (XFELs) leads to a unique set of conditions characterized by the simultaneous presence of heated electrons in a cold ionic lattice. In this work, we analyze the effect of electronic heating on the dynamic structure factor (DSF) in bulk aluminum (Al) with a face-centered cubic lattice and in silicon (Si) with a crystal diamond structure using first-principles linear-response time-dependent density functional theory simulations. We find a thermally induced red shift of the collective plasmon excitation in both materials. In addition, we show that the heating of the electrons in Al can lead to the formation of a double-plasmon peak due to the extension of the Landau damping region to smaller wave numbers. Finally, we demonstrate that thermal effects generate a measurable and distinct signature (peak-valley structure) in the DSF of Si at small frequencies. Our simulations indicate a variety of new features in the spectrum of x-ray-driven solids, specifically at finite momentum transfer, which can be probed in upcoming x-ray Thomson scattering experiments at various XFEL facilities.

Keywords: x-ray free electron laser; x-ray Thomson scattering; time-dependent density functional theory

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  • HIBEF

Permalink: https://www.hzdr.de/publications/Publ-39475


Spatial computational modelling illuminates the role of the tumour microenvironment for treating glioblastoma with immunotherapies

Mongeon, B.; Hébert-Doutreloux, J.; Surendran, A.; Karimi, E.; Fiset, B.; Quail, D. F.; Walsh, L. A.; Jenner, A. L.; Craig, M.

Abstract

Glioblastoma is the most common and deadliest brain tumour in adults, with a median survival of 15 months under the current standard of care. Immunotherapies like immune checkpoint inhibitors and oncolytic viruses have been extensively studied to improve this endpoint. However, most thus far have failed. To improve the efficacy of immunotherapies to treat glioblastoma, new single-cell imaging modalities like imaging mass cytometry can be leveraged and integrated with computational models. This enables a better understanding of the tumour microenvironment and its role in treatment success or failure in this hard-to-treat tumour. Here, we implemented an agent-based model that allows for spatial predictions of combination chemotherapy, oncolytic virus, and immune checkpoint inhibitors against glioblastoma. We initialised our model with patient imaging mass cytometry data to predict patient-specific responses and found that oncolytic viruses drive combination treatment responses determined by intratumoral cell density. We found that tumours with higher tumour cell density responded better to treatment. When fixing the number of cancer cells, treatment efficacy was shown to be a function of CD4 + T cell and, to a lesser extent, of macrophage counts. Critically, our simulations show that care must be put into the integration of spatial data and agent-based models to effectively capture intratumoral dynamics. Together, this study emphasizes the use of predictive spatial modelling to better understand cancer immunotherapy treatment dynamics, while highlighting key factors to consider during model design and implementation.

Keywords: Glioblastoma; Immune checkpoint blockade; Oncolytic virus; Cancer immunotherapy; Agent-based model; Imaging mass cytometry; Mathematical Modelling of Cancer Treatment

Permalink: https://www.hzdr.de/publications/Publ-39474


Cylindrical compression of thin wires by irradiation with a Joule-class short pulse laser

Laso García, A.; Yang, L.; Bouffetier, V.; Appel, K.; Bähtz, C.; Hagemann, J.; Höppner, H.; Humphries, O.; Kluge, T.; Mishchenko, M.; Nakatsutsumi, M.; Pelka, A.; Preston, T. R.; Randolph, L.; Zastrau, U.; Cowan, T.; Huang, L.; Toncian, T.

Abstract

Equation of state measurements at Jovian or stellar conditions are currently conducted by dynamic shock compression driven by multi-kilojoule multi-beam nanosecond-duration lasers. These experiments require precise design of the target and specific tailoring of the spatial and temporal laser profiles to reach the highest pressures. At the same time, the studies are limited by the low repetition rate of the lasers. Here, we show that by the irradiation of a thin wire with single beam Joule-class short-pulse laser, a converging cylindrical shock is generated compressing the wire material to conditions relevant for the above applications. The shockwave was observed using Phase Contrast Imaging employing a hard X-ray Free Electron Laser with unprecedented temporal and spatial sensitivity. The data collected for Cu wires is in agreement with hydrodynamic simulations of an ablative shock launched by a highly-impulsive and transient resistive heating of the wire surface. The subsequent cylindrical shockwave travels towards the wire axis and is predicted to reach a compression factor of 9 and pressures above 800 Mbar. Simulations for astrophysical relevant materials underline the potential of this compression technique as a new tool for high energy density studies at high repetition rates.

Keywords: XFEL; shock compression; PCI; short pulse laser; relativitic plasma

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  • HIBEF

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Permalink: https://www.hzdr.de/publications/Publ-39473


Bubble paths through open-porous foams imaged by radiography

Lappan, T.; Jiao, G.; Heinrich, J.; Trtik, P.; Shevchenko, N.; Eckert, K.; Eckert, S.

Abstract

Water electrolysers split liquid water into hydrogen and oxygen gas in an electrochemical reaction. The porous transport layer (PTL) is an essential component in electrolysers, transporting the electrolyte to the anode. In the opposite direction, the PTL transports the oxygen away from the anode, resulting in a complex counterflow of liquid and gas through the PTL, thus limiting the mass transport and, consequently, the conversion of electrical energy. The further development of electrolysers is intrinsically linked to so far unexplored operating ranges, in particular by increasing the electric current density, which, in turn, affects the formation and transport of gas bubbles through the PTL.
Because this gas-liquid two-phase flow is inaccessible by optical techniques, we used X-ray and neutron radiography. In a laboratory experiment, we performed imaging flow measurements of the gas transport through open-porous metal and polymer foams of different pore size and surface functionalisation. Time-resolved X-ray or neutron radiographs provide a direct mapping of the local gas fraction distribution over time, thus serving as a basis for detecting and tracking of individual bubbles. We observed preferred motions path of the bubbles rising through the pore structure, and found that especially small bubbles are significantly slowed down, even in the case of a hydrophilic surface character. In summary, the measurement results and conclusions from our experimental parameter study are available for comparison with computational fluid dynamics.

  • Poster
    20th Multiphase Flow Workshop - Conference and Short Course (MPF2024), 11.-15.11.2024, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-39472


MXenes with ordered triatomic-layer borate polyanion terminations

Li, D.; Zheng, W.; Manoj Gali, S.; Sobczak, K.; Horák, M.; Polčák, J.; Lopatik, N.; Li, Z.; Zhang, J.; Sabaghi, D.; Zhou, S.; Michałowski, P. P.; Zschech, E.; Brunner, E.; Donten, M.; Šikola, T.; Bonn, M.; Wang, H. I.; Beljonne, D.; Yu, M.; Feng, X.

Abstract

Surface terminations profoundly influence the intrinsic properties of MXenes, but existing terminations are limited to monoatomic layers or simple groups, showing disordered arrangements and inferior stability. Here we present the synthesis of MXenes with triatomic-layer borate polyanion terminations (OBO terminations) through a flux-assisted eutectic molten etching approach. During the synthesis, Lewis acidic salts act as the etching agent to obtain the MXene backbone, while borax generates BO2− species, which cap the MXene surface with an O–B–O configuration. In contrast to conventional chlorine/oxygen-terminated Nb2C with localized charge transport, OBO-terminated Nb2C features band transport described by the Drude model, exhibiting a 15-fold increase in electrical conductivity and a 10-fold improvement in charge mobility at the d.c. limit. This transition is attributed to surface ordering that effectively mitigates charge carrier backscattering and trapping. Additionally, OBO terminations provide Ti3C2 MXene with substantially enriched Li+-hosting sites and thereby a large charge-storage capacity of 420 mAh g−1. Our findings illustrate the potential of intricate termination configurations in MXenes and their applications for (opto)electronics and energy storage.

Permalink: https://www.hzdr.de/publications/Publ-39471


Data publication: Identifying magnetic phases in chemically ordered and disordered FeAl thin films

Zarzycki, A.; Anwar, S.; Bali, R.; Potzger, K.; Krupinski, M.; Marszalek, M.

Abstract

Satz von AFM/MFM und SQUID Daten, wie im zugehörigen Paper beschrieben.

Keywords: Magnetism; Ion irradiation; Nano patterning

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Permalink: https://www.hzdr.de/publications/Publ-39468


Release dynamics of nanodiamonds created by laser-driven shock-compression of polyethylene terephthalate

Heuser, B.; Bergermann, A.; Stevenson, M. G.; Ranjan, D.; He, Z.; Lütgert, J.; Schumacher, S.; Bethkenhagen, M.; Descamps, A.; Galtier, E.; Gleason, A. E.; Khaghani, D.; Glenn, G. D.; Cunningham, E. F.; Glenzer, S. H.; Hartley, N. J.; Hernandez, J.-A.; Humphries, O. S.; Katagiri, K.; Ja Lee, H.; McBride, E. E.; Miyanishi, K.; Nagler, B.; Ofori-Okai, B.; Ozaki, N.; Pandolfi, S.; Qu, C.; Thomas May, P.; Redmer, R.; Schoenwaelder, C.; Sueda, K.; Yabuuchi, T.; Yabashi, M.; Lukic, B.; Rack, A.; Zinta, L. M. V.; Vinci, T.; Benuzzi-Mounaix, A.; Ravasio, A.; Kraus, D.

Abstract

Laser-driven dynamic compression experiments of plastic materials have found surprisingly fast formation of nanodiamonds (ND) via X-ray probing. This mechanism is relevant for planetary models, but could also open efficient synthesis routes for tailored NDs. We investigate the release mechanics of compressed NDs by molecular dynamics simulation of the isotropic expansion of finite size diamond from different P-T states. Analysing the structural integrity along different release paths via molecular dynamic simulations, we found substantial disintegration rates upon shock release, increasing with the on-Hugnoiot shock temperature. We also find that recrystallization can occur after the expansion and hence during the release, depending on subsequent cooling mechanisms. Our study suggests higher ND recovery rates from off-Hugoniot states, e.g., via double-shocks, due to faster cooling. Laser-driven shock compression experiments of polyethylene terephthalate (PET) samples with in situ X-ray probing at the simulated conditions found diamond signal that persists up to 11 ns after breakout. In the diffraction pattern, we observed peak shifts, which we attribute to thermal expansion of the NDs and thus a total release of pressure, which indicates the stability of the released NDs.

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  • HIBEF

Permalink: https://www.hzdr.de/publications/Publ-39467


Data publication: Improving Beam-Based Regulation for Continuous-Wave Linear Accelerators with a Disturbance Model-Based Design

Maalberg, A.

Abstract

These data were taken by a bunch arrival time monitor during a machine development shift on ELBE accelerator on 07.06.2022. The monitor was installed after the second magnetic chicane to diagnose the application of a beam-based regulator. Two types of regulators were applied, namely a proportional regulator and an H2. The latter was of fourth order. The data revealed the different behavior of the two regulators in frequency domain.

Keywords: linear accelerators; continuous-wave mode; optimal control; field-programmable gate arrays

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Permalink: https://www.hzdr.de/publications/Publ-39465


Navigating the Data Patchwork: Strategies for Integrating Metadata Catalogs, Data Publications, and Archives

Knodel, O.; Pape, D.; Voigt, M.; Gruber, T.; Müller, S.; Juckeland, G.

Abstract

In the ever-expanding landscape of data management, navigating the diverse array of metadata catalogs such as SciCat, data publications on Invenio derivatives, and internal archives presents a formidable challenge. However, with the right strategies, this mosaic of data can be effectively combined and represented to unlock its full potential. In this talk, we delve into the intricacies of data fusion, exploring innovative approaches to harmonize metadata catalogs, data publications, and archives seamlessly.

We will discuss the importance of interoperability and standardization in facilitating the integration process, enabling disparate data sources to coalesce into a cohesive ecosystem. Through conceptional examples and case studies, we will provide insights into the practical application of strategies.

Keywords: Data repository; Data management; DAPHNE

  • Open Access Logo Poster
    DAPHNE4NFDI Annual Meeting 2024, 11.-13.03.2024, Dresden, Deutschland
  • Open Access Logo Lecture (Conference)
    NOBUGS 2024, 23.-27.09.2024, Grenoble, France

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Permalink: https://www.hzdr.de/publications/Publ-39464


Probing the Band Splitting near the Γ Point in the van der Waals Magnetic Semiconductor CrSBr

Lin, K.; Li, Y.; Ghorbani Asl, M.; Sofer, Z.; Winnerl, S.; Erbe, A.; Krasheninnikov, A.; Helm, M.; Zhou, S.; Dan, Y.; Prucnal, S.

Abstract

This study investigates the electronic band structure of chromium sulfur bromide (CrSBr) through comprehensive photoluminescence (PL) characterization. We clearly identify low-temperature optical transitions between two closely adjacent conduction-band states and two different valence-band states. The analysis on the PL data robustly unveils energy splittings, band gaps, and excitonic transitions across different thicknesses of CrSBr, from monolayer to bulk. Temperature-dependent PL measurements elucidate the stability of the band splitting below the Néel temperature, suggesting that magnons coupled with excitons are responsible for the symmetry breaking and brightening of the transitions from the secondary conduction band minimum (CBM2) to the global valence band maximum (VBM1). Collectively, these results not only reveal splitting in both the conduction and valence bands but also highlight a significant advance in our understanding of the interplay between the optical, electronic, and magnetic properties of antiferromagnetic two-dimensional van der Waals crystals.

Permalink: https://www.hzdr.de/publications/Publ-39463


Interaction of Tc with iron(II) phosphate

Börner, C.; Müller, K.; Schild, D.; Seewald, F.; Stumpf, T.; Mayordomo, N.

Abstract

Technetium (Tc) is an element originating mostly from the fission of ²³⁵U and ²³⁹Pu with a yield of 6%.¹ Therefore, ⁹⁹Tc is mainly found in high-level radioactive waste, e.g. from nuclear power or reprocessing plants.² The waste disposal is the subject of numerous studies due to the long half-life of many radionuclides (e.g. ⁹⁹Tc: 2.1 · 10⁵ years)¹ and their high radiotoxicity. One of the most accepted concepts is the deep geological underground repository. A multiple barrier system is planned to reduce the risk of a worst-case scenario, when water ingress could induce the corrosion of the canister containing the waste and, thus, radionuclide release. For the long-term safety, including the construction of effective barriers, the interaction of the radionuclides with different minerals present in the repository needs to be studied at a fundamental level. Tc shows a complex redox chemistry and is considered very mobile compared to cationic radionuclides, due to the presence of the negatively charged TcO₄⁻ under oxidising conditions. However, Tc migration decreases when Tc(VII) is reduced to Tc(IV) since it forms precipitates or is immobilized by mineral surfaces, e.g. with Fe(II) minerals (Fig. 1).³

Vivianite (Fe₃(PO₄)₂ · 8 H₂O) is a naturally occurring Fe(II) mineral under reducing conditions⁵ and can be formed by microorganisms.⁶ Phosphate phases are already being considered as an immobilisation matrix for other radionuclides relevant in deep geological repositories (e.g. ²³⁵U, ²³⁷Np, ²³⁹Pu, ²⁴³Am).⁷ ⁸

This study investigates the retention of Tc by synthetic vivianite particles as a function of pH, Tc concentration and ionic strength on a macroscopic and molecular scale. In addition, Tc(IV) reoxidation experiments were performed.⁴

The synthesis of vivianite was carried out by precipitation from a solution mixture of an iron(II) sulphate and ammonium hydrogen phosphate, as described by Roldán et al..⁹ The product was characterised by Raman microscopy, Mössbauer spectroscopy, powder X-ray diffraction and solubility studies with regard to the pH-dependent behaviour under N₂ atmosphere. The identified phase at pH 5.0 and pH 8.0 is vivianite. At pH 12.0 vivianite transforms into Fe(II)(OH)₂. The change in solid morphology due to the mineralogical modification was also observed with scanning electron microscopy.

Batch contact experiments at N₂ atmosphere were carried out to determine the interaction between vivianite particles suspended in water and KTcO₄. The Tc concentrations in solution were determined by liquid scintillation counting and the Tc-loaded solid was analysed by X-ray photoelectron spectroscopy (XPS). Kinetic contact experiments of 1 µM TcO₄⁻ show that Tc uptake by vivianite increases with longer contact time at pH 8.0 and is complete after 20 days, while no Tc retention takes place at pH 6.5. The Tc-containing solids from experiments at pH 5.0 and pH 12.0 were analysed by XPS to determine the oxidation state of the Tc and Fe. The results show that Tc(IV) was present on the solid surface in all samples analysed. It indicates that Tc removal at high pH values is due to the reductive immobilization of Tc(VII) to Tc(IV) by vivianite. However, at acidic pH values (pH 5.0) Tc(VII) reduction occurs without decreasing the Tc concentration in solution, but by XPS, formerly dissolved Tc(IV) could be detected on the solid surface.

To investigate the remobilisation of reduced Tc(IV), samples obtained after completion of Tc retention experiments at different pH were exposed to ambient atmosphere and Tc concentration was monitored for six months. Under oxidising conditions, no remobilisation of Tc takes place at pH values above pH 8.0. The immobilisation of Tc by vivianite remains complete over the course of six months. This shows a slower Tc(IV) reoxidation than in Tc(IV)-containing FeS₂ mineral phases, where reoxidation starts after 64 days.¹⁰ Additionally, an increase of Tc retention was determined at pH 2.0 and pH 3.0. This can be explained by a time-delayed immobilisation of Tc by the dissolved Fe(II).¹¹

Those promising results show a high affinity of vivianite towards Tc, aided by the reduction of Tc(VII) to Tc(IV) by structural Fe(II).

The authors acknowledge the German Federal Ministry of Education and Research (BMBF) for the financial support of the NukSiFutur TecRad young investigator group (02NUK072).¹²

References:

1 NDS-Datenbank, https://www-nds.iaea.org, (accessed 4 June 2024).
2 A. H. Meena, Y. Arai, Environ. Chem. Lett., 2017, 15, 241–263.
3 C. I. Pearce, R. C. Moore, J. W. Morad, R. M. Asmussen, S. Chatterjee, A. R. Lawter, T. G. Levitskaia, J. J. Neeway, N. P. Qafoku, M. J. Rigali, S. A. Saslow, J. E. Szecsody, P. K. Thallapally, G. Wang, V. L. Freedman, Sci. Total Environ., 2020, 716, 132849.
4 C. Börner, Masterarbeit, Technische Universität Dresden, 2023.
5 A. Al-Borno, M. B. Tomson, Geochim. Cosmochim. Acta, 1994, 58, 5373–5378.
6 J. M. McBeth, J. R. Lloyd, G. T. W. Law, F. R. Livens, I. T. Burke, K. Morris, Mineral. Mag., 2011, 75, 2419–2430.
7 P. Sengupta, J. Hazard. Mater., 2012, 235–236, 17–28.
8 M. R. Rafiuddin, G. Donato, S. McCaugherty, A. Mesbah, A. P. Grosvenor, ACS Omega, 2022, 7, 39482–39490.
9 R. Roldán, V. Barrón, J. Torrent, Clay Miner., 2002, 37, 709–718.
10 D. M. Rodríguez, N. Mayordomo, D. Schild, S. Shams Aldin Azzam, V. Brendler, K. Müller, T. Stumpf, Chemosphere, 2021, 281, 130904.
11 J. M. Zachara, S. M. Heald, B. H. Jeon, R. K. Kukkadapu, C. Liu, J. P. McKinley, A. C. Dohnalkova, D. A. Moore, Geochim. Cosmochim. Acta, 2007, 71, 2137–2157.
12 TecRad-group, https://www.hzdr.de/db/Cms?pNid=1375, (accessed 4 June 2024).

Keywords: technetium; vivianite; sorption; reduction; mineral

  • Poster
    10th International Conference on Nuclear and Radiochemistry – NRC10, 25.-30.08.2024, Brighton, United Kingdom

Permalink: https://www.hzdr.de/publications/Publ-39462


From root to shoot: tracking the journey of Eu(III) through hydroponically grown plants

Klotzsche, M.; Steudtner, R.; Vogel, M.; Drobot, B.; Dück, V.; Schymura, S.; Raff, J.; Stumpf, T.

Abstract

Lanthanides (Ln) are essential for various industrial and scientific applications and serve as inactive analogs for trivalent actinides (An) such as curium and americium. Understanding the bioaccumulation behavior of non-essential metals like Ln and An in plants is crucial for food safety and the development of effective phytoremediation strategies.
Our aim is to gain a mechanistic understanding of the interaction between Ln/An and plants. Using laser spectroscopy and chemical microscopy in combination with factor analysis, liquid chromatography, thermodynamic modelling, autoradiography, biochemical methods and inductively coupled plasma mass spectrometry, we followed the path of Eu(III) through sand oat (Avena strigosa). We determined Eu(III) concentration and speciation change in the hydroponic medium due to root exudate release. We identified apoplastic (71%) and symplastic (10%) fractions of Eu(III) in the roots and visualized the metal’s microscopic species distribution in root tissue and cells. From a macroscopic point of view, we demonstrated that over 99.35% of bioassociated Eu(III) accumulated in the root through a multistage bioassociation process. The translocation into green plant parts is thereby realized by xylem sap via a Eu(III) malate or citrate complex. Furthermore, we visualized the distribution of the radionuclide in roots and leaves in experiments with Eu-152.

Keywords: europium; speciation; bioassociation; hydroponics; laser spectroscopy; liquid chromatography; autoradiography; plant uptake; radionuclides

  • Lecture (others) (Online presentation)
    1st Webinar of the Alliance‘s Young Researcher, 19.09.2024, online, online

Permalink: https://www.hzdr.de/publications/Publ-39461


The effect of Ar+ and N+ ion irradiation on the thermally induced evolution of the structural and magnetic properties of Co/Pt and Pt/Co bilayered stacks

Pedan, R.; Kruhlov, I.; Makushko, P.; Dubikovskyi, O.; Kosulya, O.; Orlov, A.; Bodnaruk, A.; Golub, V.; Munnik, F.; Hübner, R.; Makarov, D.; Vladymyrskyi, I.

Abstract

The application of Co-Pt thin films as functional elements of novel nanoelectronics and spintronics devices requires the formation of a homogeneous ferromagnetic CoPt phase with tunable magnetic properties. A diffusion-controlled synthesis of this ferromagnetic phase can be implemented through the annealing of deposited Co/Pt bilayers. Apart from thermal treatment, both structural and magnetic properties of such layered stacks can be affected by ion preirradiation. In this work, we, therefore, studied the effect of a two-stage process consisting of preirradiation with 110 keV Ar+/N+ ions followed by post-annealing in vacuum at 550 °С for 30 min on the evolution of the structural, chemical, and magnetic properties of Co/Pt/substrate and Pt/Co/substrate heterostructures. The results obtained for such two-stage processing were compared to those received after single-stage vacuum annealing. It was found that when ion preirradiation is followed by annealing, the diffusion-driven intermixing of Pt and Co leading to the formation of the ferromagnetic Co-Pt phase is slowed down compared to the non-irradiated samples, which is associated with the barrier effect of implanted projectiles. Furthermore, we demonstrate that preirradiation does not compromise the magnetic properties of the samples. For instance, preirradiation leads to a coercivity increase of up to 38% compared to the non-irradiated annealed samples which is attributed to the presence of remaining paramagnetic Pt between the grains of the ferromagnetic A1-CoPt phase. We demonstrate that the applied two-stage processing (consisting of ion preirradiation followed by thermal annealing) of magnetic thin films is a promising approach for tailoring their magnetic properties such as the in-plane coercivity, saturation, and effective magnetization.

Keywords: magnetic thin films; ion irradiation; diffusion; Co-Pt alloy; crystal structure

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Permalink: https://www.hzdr.de/publications/Publ-39460


Data publication: An approach for in situ fouling monitoring in heat exchangers using electrical impedance spectroscopy

de Assis Dias, F.; Kryk, H.; Schleicher, E.; Nurjahan, T.; Pelz, P.; Bart, H.-J.; von Harbou, E.; Scholl, S.; Jasch, K.; Hampel, U.

Abstract

The dataset presented in this study is focused on the in situ monitoring of organic fouling in a plate heat exchanger using electrical impedance spectroscopy (EIS). The primary objective was to accurately determine the thickness of fouling layers that develop over time during heat exchanger operation. The experiments were conducted using an impedance analyzer (Sciospec ISX-3) configured in a four-terminal setup with two electrodes. The counter and reference electrodes were connected to a probe positioned at the top of the chamber, while the working and sensing electrodes were connected to the heating plate of the heat exchanger. This configuration allowed for the precise measurement of impedance across the fouling layer. The amplitude of the excitation signal was set to 1 V (rms). This value was chosen to maintain linearity at high frequencies and to ensure a high signal-to-noise ratio (SNR). The impedance spectra were recorded across a frequency range of 10 Hz to 2 MHz. The spectrum included 50 measurement points that were logarithmically spaced within this range to capture detailed impedance characteristics across different frequencies. Impedance data were sampled at a rate of 45 mHz, and measurements were collected over a duration of approximately 600 minutes, allowing for continuous monitoring of the fouling development process. The raw data consists of impedance measurements, reflecting changes in the electrical properties of the fouling layer as it accumulates on the heat exchanger surfaces. The data points in the spectrum provide insights into the relationship between fouling thickness and impedance across various frequencies, which is critical for developing models to predict fouling behavior in heat exchangers.This dataset is valuable for researchers and engineers interested in non-invasive fouling monitoring techniques, offering a foundation for improving heat exchanger efficiency through real-time fouling detection and characterization.

Keywords: electrical impedance spectroscopy; fouling monitoring; heat exchanger; fouling thickness

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Permalink: https://www.hzdr.de/publications/Publ-39459


Ab initio-simulated optical response of hot electrons in gold and ruthenium

Akhmetov, F.; Vorberger, J.; Milov, I.; Makhotkin, I.; Ackermann, M.

Abstract

Optical femtosecond pump-probe experiments allow to measure the dynamics of ultrafast heating of metals with high accuracy. However, the theoretical analysis of such experiments is often complicated because of the indirect connection of the measured signal and the desired temperature transients. Establishing such a connection requires an accurate model of the optical constants of a metal, depending on both the electron temperature Te and the lattice temperature Tl. In this paper, we present first-principles simulations of the two-temperature scenario with Te ≫ Tl, showing the optical response of hot electrons to laser irradiation in gold and ruthenium. Comparing our simulations with the Kubo-Greenwood approach, we discuss the influence of electron-phonon and electron-electron scattering on the intraband contribution to optical constants. Applying the simulated optical constants to the analysis of ultrafast heating of ruthenium thin films we highlight the importance of the latter scattering channel to understand the measured heating dynamics.

Keywords: laser; gold; ruthenium; relaxation; energy transfer

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Permalink: https://www.hzdr.de/publications/Publ-39458


Adatom-mediated damage of two-dimensional materials under the electron beam in a transmission electron microscope

Jain, M.; Kretschmer, S.; Meyer, J.; Krasheninnikov, A.

Abstract

The interaction of energetic electrons with the specimen during imaging in a transmission electron microscope (TEM) can give rise to the formation of defects or even complete destruction of the sample. This is particularly relevant to atomically thin two-dimensional (2D) materials. Depending on electron energy and material type, different mechanisms such as knock-on (ballistic) damage, inelastic interactions including ionization and excitations, as well as beam-mediated chemical etching can govern defect production. Using first-principles calculations combined with the McKinley-Feshbach formalism, we investigate damage creation in two representative 2D materials, MoS2 and hexagonal boron nitride (hBN) with adsorbed single adatoms (H, C, N, O, etc.), which can originate from molecules always present in the TEM column. We assess the ballistic displacement threshold energies T for the host atoms in 2D materials when adatoms are present and demonstrate that T can be reduced, as chemical bonds are locally weakened due to the formation of new bonds with the adatom. We further calculate the partial and total cross sections for atom displacement from MoS2 and hBN, compare our results to the available experimental data, and conclude that adatoms should play a role in damage creation in MoS2 and hBN sheets at electron energies below the knock-on threshold of the pristine system, thus mediating the buildup of electron beam-induced damage.

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Permalink: https://www.hzdr.de/publications/Publ-39457


Towards ion stopping power experiments with the laser-driven LIGHT beamline

Nazary, H.; Metternich, M.; Schumacher, D.; Neufeld, F.; Grimm, S. J.; Brabetz, C.; Kroll, F.; Brack, F.-E.; Blažević, A.; Schramm, U.; Bagnoud, V.; Roth, M.

Abstract

The main emphasis of the Laser Ion Generation, Handling and Transport (LIGHT) beamline at GSI Helmholtzzentrum für Schwerionenforschung GmbH are phase-space manipulations of laser-generated ion beams. In recent years, the LIGHT collaboration has successfully generated and focused intense proton bunches with an energy of 8 MeV and a temporal duration shorter than 1 ns (FWHM). An interesting area of application that exploits the short ion bunch properties of LIGHT is the study of ion-stopping power in plasmas, a key process in inertial confinement fusion for understanding energy deposition in dense plasmas. The most challenging regime is found when the projectile velocity closely approaches the thermal plasma electron velocity ( v_i ≈ v_e,th), for which existing theories show high discrepancies. Since conclusive experimental data are scarce in this regime, we plan to conduct experiments on laser-generated plasma probed with ions generated with LIGHT at a higher temporal resolution than previously achievable. The high temporal resolution is important because the parameters of laser-generated plasmas are changing on the nanosecond time scale. To meet this goal, our recent studies have dealt with ions of lower kinetic energies. In 2021, laser accelerated carbon ions were transported with two solenoids and focused temporally with LIGHT's radio frequency cavity. A bunch length of 1.2 ns (FWHM) at an energy of 0.6 MeV u −1
was achieved. In 2022, protons with an energy of 0.6 MeV were transported and temporally compressed to a bunch length of 0.8 ns. The proton beam was used to measure the energy loss in a cold foil. Both the ion and proton beams will also be employed for energy loss measurements in a plasma target.

Keywords: stopping power; laser plasma acceleration; laser acceleration; LIGHT; energy loss; TNSA

Permalink: https://www.hzdr.de/publications/Publ-39456


Data publication: Efficient density functional theory directed identification of siderophores with increased selectivity towards indium and germanium

Hintersatz, C.; Tsushima, S.; Kaufer, T.; Kretzschmar, J.; Thewes, A.; Pollmann, K.; Jain, R.

Abstract

.log Dateien der durchgeführten DFT Kalkulationen, welche die geometrieoptimierten Strukturen der Siderophore beinhalten. Desweiteren Excel files mit den Rohdaten zu Bindungsversuchen und Berechnungen der Reaktionsenergien.

Keywords: Agrobactin; Fimsbactin A; selective recovery; density functional theory; indium; germanium; screening

Related publications

Permalink: https://www.hzdr.de/publications/Publ-39455


Efficient density functional theory directed identification of siderophores with increased selectivity towards indium and germanium

Hintersatz, C.; Tsushima, S.; Kaufer, T.; Kretzschmar, J.; Thewes, A.; Pollmann, K.; Jain, R.

Abstract

Siderophores are promising ligands for application in novel recycling and bioremediation technologies, as they can selectively complex a variety of metals. However, with over 250 known siderophores, the selection of suiting complexant in the wet lab is impractical. Thus, this study established a density functional theory (DFT) based approach to efficiently identify siderophores with increased selectivity towards target metals on the example of germanium and indium. Considering 239 structures, chemically similar siderophores were clustered, and their complexation reactions modeled utilizing DFT. The calculations revealed siderophores with, compared to the reference siderophore desferrioxamine B (DFOB), up to 128 % or 48 % higher selectivity for indium or germanium, respectively. Experimental validation of the method was conducted with fimsbactin A and agrobactin, demonstrating up to 40% more selective indium binding and at least sevenfold better germanium binding than DFOB, respectively. The results generated in this study open the door for the utilization of siderophores in eco-friendly technologies for the recovery of many different critical metals from various industry waters and leachates or bioremediation approaches. This endeavor is greatly facilitated by applying the herein-created database of geometry-optimized siderophore structures as de novo modeling of the molecules can be omitted.

Keywords: Agrobactin; Fimsbactin A; selective recovery; density functional theory; indium; germanium; screening

Related publications

Permalink: https://www.hzdr.de/publications/Publ-39454


Efficient THz Upconversion with Dirac Materials

Uaman Svetikova, T. A.; Ilyakov, I.; Ponomaryov, O.; de Oliveira, T.; Berger, C.; Fürst, L.; Bayer, F.; Deinert, J.-C.; Prajapati, G. L.; Arshad, A.; Novik, E. G.; Pashkin, O.; Helm, M.; Winnerl, S.; Buhmann, H.; Molenkamp, L. W.; Kiessling, T.; Kovalev, S.; Astakhov, G.

Abstract

Current communication technologies are constrained to sub-THz bands due to the frequency limits of traditional nonlinear components. We introduce a new approach to upconverting weak sub-THz signals into multiple THz bands using a high-mobility HgTe-based heterostructure with Dirac electronic state dispersion. Building on our previous success in achieving record third harmonic generation in this material, we anticipated efficient frequency mixing and a strong THz response across various input frequency combinations. With a field conversion efficiency exceeding 2% in a sub-100 nm HgTe layer at room temperature, we hope to open the door to highly integrated THz communication devices with very high data transfer rates.

Keywords: Nonlinear effects; THz; HgTe

Involved research facilities

  • T-ELBE
  • F-ELBE
  • Poster
    ELI Summer School 2024, 02.-06.09.2024, Szeged, Hungary

Permalink: https://www.hzdr.de/publications/Publ-39453


THz Nonlinear effects in topological HgTe

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

Abstract

High harmonic generation (HHG) is a nonlinear optical process that has a range of applications in various fields, including ultrashort pulse measurements, material characterization, and imaging microscopy. Recently, there has been increasing interest in studying the THz nonlinearity and efficient third harmonic generation (THG) in Dirac materials such as graphene [1]. It is natural to assume that other Dirac materials, such as topological insulators (TI), could also exhibit similar effects [2,3]. In particular, topological states can be found in HgTe quantum wells with a thickness of more than 6.3 nm [4].

Keywords: Nonlinear effects; HgTe; third harmonic generation

Involved research facilities

  • T-ELBE
  • F-ELBE
  • Poster
    Cluster Retreat 2024 Weimar, 25.-27.03.2024, Weimar, Germany

Permalink: https://www.hzdr.de/publications/Publ-39452


Efficient THz third harmonic generation in topological HgTe

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

Abstract

High harmonic generation (HHG) is a nonlinear optical process that has a range of applications in various fields, including ultrashort pulse measurements, material characterization, and imaging microscopy. Recently, there has been increasing interest in studying the THz nonlinearity and efficient third harmonic generation (THG) in Dirac materials such as graphene [1]. It is natural to assume that other Dirac materials, such as topological insulators (TI), could also exhibit similar effects [2,3]. In particular,
topological states can be found in HgTe quantum wells with a thickness of more than 6.3 nm [4].
1. Hafez, H. A. et al., Nature 561, 507-511 (2018).
2. Kovalev, S. et al. Quantum Materials 6, 84 (2021)
3. Tielrooij, K.-J. et al. Light Sci. Appl. 11, 315 (2022).
4. Bernevig, B. A. et al. Science 314, 1757-1761 (2006).

Keywords: Nonlinear effects; THz; HgTe; Third harmonic generation

Involved research facilities

  • T-ELBE
  • F-ELBE
  • Poster
    Topological Electronics and Bosonics : from Concepts to Devices, 28.01.-02.02.2024, Aussois, France
  • Poster
    The 25th International Conference on the Electronic Properties of Two-Dimensional Systems (EP2DS-25) and 21st International Conference on Modulated Semiconductor Structures (MSS-21), 09.-14.07.2023, Grenoble, France
  • Poster
    Fourth QMA Retreat (Leipzig), 25.-27.09.2023, Leipzig, Germany

Permalink: https://www.hzdr.de/publications/Publ-39451


Data and code: Investigation of the effect of filling degree on particle segregation in a rotating drum using non-invasive measurement techniques and DEM simulations

Papapetrou, T. N.; Bieberle, M.; Barthel, F.; Hampel, U.; Lecrivain, G.

Abstract

Original video camera data, UFXCT image data and DEM simulation data used in the associated publication; code used for the processing; and the final processed data.

Involved research facilities

  • ROFEX
  • Data Center

Downloads

Permalink: https://www.hzdr.de/publications/Publ-39449


Concept for an exchangeable metadata structure for electronic labbooks based on Mediawiki

Gruber, T.; Pape, D.; Voigt, M.; Knodel, O.

Abstract

An essential challenge by creating FAIR datasets is the often underestimated I, which stands for interoperability. Especially for a dataset that is meant to be exported from its ecosystem, it is important to store the metadata and data in the appropriate exchangeable format based on standards.
One possible source for metadata is an electronic lab notebook that stores it in a structured manner. In many cases the internal structure does not match any established metadata scheme and a mapping is required for a meaningful export. This talk presents a concept of what is necessary to make a generic export from an electronic Labbook based on semantic Mediawiki for ingestion into SciCat or interoperable Nexus files.
First an existing scheme (e.g. Nexus application class) needs to be imported and the class dependencies is stored. Reference to the origin of created classes and properties are essential. Within Mediawiki, templates are used to assign a set of properties to a page. Together with a configuration which describes through which properties the templates are interconnected a generic export is possible. Now by selecting a certain measurement, the export script can extract all essential metadata to create e.g. a SciCat export with project, instrument, sample and dataset information or create a nexus file and knows which groups needs to be created and under which path a property is stored.
Since the information is bound to the property, the application of a mapping can be optimized in an iterative manner. This makes it a flexible procedure that is perfectly usable for existing documentation where metadata schemes are applied at a later stage or need to be updated. In addition, the reference to the original metadata scheme is known in the whole pipeline and could be included in the export.

Keywords: ELN; exchange format; metadata schema; Ontologies

  • Poster
    DAPHNE4NFDI Annual Meeting 2024, 11.03.2024, Helmholtz-Zentrum Dresden-Rossendorf, Germany

Permalink: https://www.hzdr.de/publications/Publ-39448


Categorizing current-voltage curves in single-molecule junctions and their comparison to Single-Level Model

Schmidt, G. A.

Abstract

This thesis investigates the mechanically controlled break junctions, with a particular emphasis on elucidating the behaviour of molecular currents at room temperature. The core of this experimental investigation involves a detailed analysis of conductance, examining how it varies over time and with changes in the gap between electrodes. Additionally, this study thoroughly evaluates transmission properties, coupling effects, and current characteristics. A pivotal aspect of the research was the meticulous current measurement, followed by carefully selecting optimal data sets. This process set the stage for an in-depth analysis of resonant tunnelling phenomena observed through a single channel. Notably, these experiments were conducted under open atmospheric conditions at room temperature. A significant finding from this study is the recognition that our current model requires refinement. This adjustment is necessary to encapsulate a broader spectrum of molecular transport mechanisms more accurately. Furthermore, this work significantly advances our comprehension of quantum effects in single-molecule junctions, particularly concerning similar molecules to Corannulene extending to some organometallics. One of the essential disclosures is the identification of deviations in the transport model, primarily attributable to electron-electron interactions. This insight is crucial as it paves the way for developing a more comprehensive and precise model, enhancing our understanding of molecular-scale electronic transport.

Keywords: slm; single-level model; mcbj; single molecule

  • Master thesis
    Tu Dresden, 2024
    Mentor: Prof. A. Erbe, Prof. F. Moresco

Permalink: https://www.hzdr.de/publications/Publ-39446


Evolution of current- and pressure-driven instabilities in relativistic jets

Musso, M.; Bodo, G.; Mamatsashvili, G.; Rossi, P.; Mignone, A.

Abstract

Instabilities in relativistic magnetized jets are thought to be deeply connected to their energy dissipation properties and to the consequent acceleration of the non-thermal emitting relativistic particles. Instabilities lead to the development of small-scale dissipative structures, in which magnetic energy is converted in other forms. In this paper we present three-dimensional numerical simulations of the instability evolution in highly magnetized plasma columns, considering different kinds of equilibria. In fact, the hoop stresses related to the azimuthal component of magnetic field can be balanced either by the magnetic pressure gradient (force-free equilibria, FF) or by the thermal pressure gradient (pressure-balanced equilibria, PB) or by a combination of the two. FF equilibria are prone to current-driven instabilities (CDI), while PB equilibria are prone to pressure-driven instabilities (PDI). We perform a global linear stability analysis, from which we derive the different instability properties in the two regimes, showing that PDI have larger growth rates and are also unstable for high wavenumbers. The numerical simulations of the non-linear instability evolution show similar phases of evolution in which the formation of strong current sheets is followed by a turbulent quasi-steady state. PDI are however characterized by a faster evolution, by the formation of smaller scale dissipative structures and larger magnetic energy dissipation.

Permalink: https://www.hzdr.de/publications/Publ-39445


Digital sample management and documentation of analytical methods – Development of an electronic lab notebook at the Helmholtz-Institute Freiberg

Schaller, T.; Gruber, T.; Steinmeier, L.; Rau, F.

Abstract

At the Helmholtz-Institute Freiberg for Resource Technology (HIF), researchers develop new technologies to improve circular economy. In this context, different types of samples (e.g. rock samples, recycling material) play an important role. The sample passes through different states and labs – starting at the sample preparation, through the analysis of the particular sample to the final storage.
With electronic lab notebooks (ELNs) this entire process is digitized, thus improving findability, accessibility, interoperability and reusability (FAIR) of the samples and their corresponding data. Once the sample is registered in the system, every further work on the sample will be connected to this sample, explicitly. Thus, all important metadata can be recorded digitally in a structured way.
At the HIF, we are developing an ELN based on semantic MediaWiki. For this, we are incorporating all analytical methods existing at the HIF into the system. Thus, scientists and lab personnel need to adjust accustomed processes of data documentation. Therefore, the system needs to be as user friendly and as close to the familiar processes a possible. Where this is not possible, future users need to be motivated and included into the entire development process. For this, personal exchange between scientists/ lab personnel and developers is of great importance.
In this contribution, we will discuss the challenges in the development of an ELN, including technical and personal aspects and present the structure of our ELN.

Keywords: Electronic Lab Notebook; Sample management; semantic MediaWiki; Digital sample registration

  • Poster
    HMC conference 2024, 04.-06.11.2024, online, online

Permalink: https://www.hzdr.de/publications/Publ-39443


Digitale Probenverwaltung und Dokumentation analytischer Methoden - Entwicklung eines Elektronischen Laborbuchs in MediaWiki am Helmholtz Institut Freiberg (HIF)

Schaller, T.; Gruber, T.; Steinmeier, L.; Rau, F.

Abstract

Am Helmholtz-Institut Freiberg (HIF) werden neue Technologien zur Verbesserung der nachhaltigen Kreislaufwirtschaft entwickelt. Hierbei spielen verschiedenste Arten von Proben (z. B. Gesteinsproben, Recyclingmaterial usw.) eine zentrale Rolle. Jede Probe durchläuft dabei verschiedene Stadien und Labore: von der Probenpräparation bis hin zur Analyse der Proben mit verschiedensten Methoden, um am Ende als Rückstellprobe eingelagert zu werden.
Mit Hilfe eines Elektronischen Laborbuchs (Electronic Lab Notebook, ELN) soll dieser gesamte Prozess digitalisiert und die Transparenz erhöht werden. Durch die Registrierung von Proben im System wird jede weitere Verarbeitung und jede Messung eindeutig mit einer Probe verknüpft. Wichtige Metadaten können so strukturiert und digital erfasst werden.
Am HIF wird derzeit ein ELN auf Basis der Software MediaWiki eingeführt. Hierzu werden alle analytischen Methoden digital und strukturiert erfasst. Außerdem müssen bestehende Prozesse der Datendokumentation durch die Forschenden und Mitarbeiter*innen im Labor angepasst werden.
In diesem Beitrag werden wir die Herausforderungen bei der Entwicklung des ELN näher erläutern sowie Datenstrukturen vorstellen.

Keywords: Electronic Lab Notebook; Digital sample registration; semantic MediaWiki

  • Open Access Logo Poster
    SaxFDM2024, 17.09.2024, Freiberg, Germany

Permalink: https://www.hzdr.de/publications/Publ-39442


Highlight selection of radiochemistry and radiopharmacy developments by editorial board

Scott, P.; Penuelas, I.; Rey, A.; Aime, S.; Ambikalmajan, P.; Antunes, I.; Cleeren, F.; Liu, Z.; Ellis, B.; Kahts, M.; Ekoume, F.; Chaple, I.; Bernardes, E.; Behe, M.; Huang, Y.; Mikolajczak, R.; Furumoto, S.; Elrefaei, A.; Kopka, K.

Abstract

Background: The Editorial Board of EJNMMI Radiopharmacy and Chemistry releases a biannual highlight commentary to update the readership on trends in the field of radiopharmaceutical development.
Main Body: This selection of highlights provides commentary on 19 different topics selected by each coauthoring Editorial Board member addressing a variety of aspects ranging from novel radiochemistry to first-in-human application of novel radiopharmaceuticals.
Conclusion: Trends in radiochemistry and radiopharmacy are highlighted. Hot topics cover the entire scope of EJNMMI Radiopharmacy and Chemistry, demonstrating the progress in the research field in many aspects.

Keywords: Highlight Articles; Radiochemistry; Radiopharmacy; Radiopharmaceutical Sciences; Nuclear Medicine

Involved research facilities

  • ZRT

Permalink: https://www.hzdr.de/publications/Publ-39441


Autotarget*: A Distributed Robot Operating System Framework for Autonomous Aerial Swarms

Adoni, W. Y. H.; Lorenz, S.; Junaidh, S. F.; Gloaguen, R.; Kühne, T. D.-S.

Abstract

Robot Operating System (ROS) has proven itself as a viable framework for developing robot-related applications. It offers features such as hardware abstraction, low-level device support, inter-process communication, and useful libraries for autonomous robot systems. Concerning aerial robots, commonly called unmanned aerial vehicles (UAV) or drones, ROS provides unfortunately very basic functions. Moreover, it does not guarantee real-time operation, as it runs under Linux. Consequently, it is difficult to implement advanced ROS applications that involve a swarm of drones that need to communicate with each other to carry out a common mission. This paper proposes an extended version of the ROS framework called autotarget*, which provides a set of efficient functions designed for distributed operation on multiple UAVs flying at the same time. autotarget* relies on a multi-tier architecture with a decentralized communication layer, enabling intra-UAV messaging as well as the scalability of swarm UAVs. It has a set of daemons whose feature is to regulate the swarm's consensus control and failover policy to ensure convergence towards a common goal. Experiments with real-world swarms revealed that autotarget* is portable and satisfies the performance requirements for collaborative mission applications. We further conducted a coverage planning mission using the parallel back-and-forth algorithm, which demonstrated the efficiency of the framework in terms of time and energy. Our work should pave the way for an open-source environment dedicated to simplifying collaborative ROS application development, particularly for multi-UAV systems.

Keywords: Robot Operating System; Aerial Swarms; Unmanned Aerial Vehicles; Consensus Control; Communication Protocol; Swarm Intelligence; Integrated Development Environment; Communication Architecture

Related publications

  • Contribution to proceedings
    2024 21st International Conference on Ubiquitous Robots (UR), 24.-27.06.2024, New York, NY, USA
    International Conference on Ubiquitous Robots (UR), IEEE: IEEE, 979-8-3503-6107-0
    DOI: 10.1109/UR61395.2024.10597509
    Cited 1 times in Scopus

Permalink: https://www.hzdr.de/publications/Publ-39439


Spin Effect to Regulate the Electronic Structure of Ir-Fe Aerogels for Efficient Acidic Water Oxidation

Gao, C.; Wang, J.; Hübner, R.; Zhan, J.; Zhao, M.; Li, Y.; Cai, B.

Abstract

"Spin" has been recently reported as an important degree of electronic freedom to promote catalysis, yet how it influences electronic structure remains unexplored. This work reports the spin-induced orbital hybridization in Ir-Fe bimetallic aerogels, where the electronic structure of Ir sites is effectively regulated by tuning the spin property of Fe atoms. The spin-optimized electronic structure boosts oxygen evolution reaction (OER) electrocatalysis in acidic media, resulting in a largely improved catalytic performance with an overpotential of as low as 236 mV at 10 mA cm-2. Furthermore, the gelation kinetics for the aerogel synthesis is improved by an order of magnitude based on the introduction of a magnetic field. Density functional theory calculation reveals that the increased magnetic moment of Fe (3d orbital) changes the d-band structure (i.e., the d-band center and bandwidth) of Ir (5d orbital) via orbital hybridization, resulting in optimized binding of reaction intermediates. This strategy builds the bridge between the electron spin theory with the d-band theory and provides a new way for the design of high-performance electrocatalysts by using spin-induced orbital interaction.

Involved research facilities

Related publications

Permalink: https://www.hzdr.de/publications/Publ-39438


High density optical data storage with atomic defects in SiC over million years

Astakhov, G.; Hollenbach, M.; Kasper, C.; Erb, D.; Bischoff, L.; Hlawacek, G.; Kraus, H.; Kada, W.; Ohshima, T.; Helm, M.; Facsko, S.; Dyakonov, V.

Abstract

There is an urgent need to increase the global data storage capacity, as current approaches lag behind the exponential growth of data generation driven by the Internet, social media and cloud technologies. In addition to increasing storage density, new solutions should provide long-term data archiving that goes far beyond traditional magnetic memory, optical disks and solid-state drives. We propose a concept of energy-efficient, ultralong, high-density data archiving based on optically active atomic-size defects in a radiation resistance material, silicon carbide (SiC) [1]. The information is written in these defects by focused ion beams and read using photoluminescence or cathodoluminescence. The temperature-dependent deactivation of these defects suggests a retention time minimum over a few generations under ambient conditions. With near-infrared laser excitation, grayscale encoding and multi-layer data storage, the areal density corresponds to that of Blu-ray discs. Furthermore, we demonstrate that the areal density limitation of conventional optical data storage media due to the light diffraction can be overcome by focused electron-beam excitation.

Keywords: Defects; SiC; Data storage; Ion implantation

Involved research facilities

Related publications

  • Lecture (Conference)
    816. WE-Heraeus-Seminar "Silicon Carbide: Classical and Quantum Technologies", 29.07.2024, Bad Honnef, Germany

Permalink: https://www.hzdr.de/publications/Publ-39437


Materials and Constructional Design for Electric Vehicles: A Review

Kalhor, A.; Dykas, J.; Rodak, K.; Grajcar, A.

Abstract

In this article, electric vehicles (EVs) are generally introduced, and the benefits of shifting
from conventional automobiles toward EVs are discussed. Batteries, as the core technology
of EVs, are then addressed, and various battery types are reviewed. Next, the critical role of
copper as one of the primary materials essential for various EV components, as well as the
expected growth in its demand in the near future, are discussed. Following that, the
significance of using advanced high-strength steels (AHSSs) in the body structure of EVs to
reduce weight while maintaining safety requirements is emphasized, and different types of
AHSSs are generally mentioned. Subsequently, common metal forming and joining methods
for manufacturing and assembling EV components are reviewed. After that, the importance
of proper EV constructional design is highlighted, and the strategic battery pack placement
for safety and effective weight distribution is highlighted. The importance of using
lightweight materials that offer high strength-to-weight ratios in the body structure of EVs
and their benefits for improving the efficiency of EVs through increasing the driving range
are also outlined. In addition, the importance of responsible end-of-life actions, including
recycling or responsible disposal of EV components after their functional lifespan, is also
overviewed. Finally, useful strategies for facilitating wider adoption of EVs are discussed,
and alternative options for addressing air pollution and global warming are mentioned.

Keywords: electric vehicle; Li-ion batteries; automobile materials; copper alloys; advanced high- strength steels; constructional design

  • Open Access Logo Advances in Science and Technology Research Journal 19(2025)1, 178-196
    Online First (2024) DOI: 10.12913/22998624/195457

Permalink: https://www.hzdr.de/publications/Publ-39436


Validity of Toughness Measurements From Miniature Specimens Failing in Different Fracture Modes

Ortner, S.; Sanchez, M.; Echols, J.; Cicero, S.; Chekhonin, P.

Abstract

Using miniature compact tension (mini-C(T)) (4mm thick, 0.16T) specimens to determine
toughness in reactor pressure vessel (RPV) steels permits the ductile-to-brittle transition
temperature to be derived from small amounts of material and allows more effective use of
surveillance specimens. However, questions have been raised as to whether the failure
mechanisms are the same in miniature and large specimens, something that must be ensured
when transferring fracture results obtained in mini-C(T) specimens to larger components.
This work, performed within the FRACTESUS project, presents toughness measurements
and detailed fractography on both a homogeneously brittle base metal and a relatively
ductile, inhomogeneous weld to assess the transferability of fracture data. The fractography
shows that brittle fracture initiates within the part of specimen experiencing small-scale
yielding (SSY), so long as the toughness measurement is valid. Similarly, although the
precrack front asymmetry appears more marked in smaller specimens, as long as the
deviation from planarity is within the American Society for Testing and Materials (ASTM)
E1921 limits, the asymmetry does not affect the location of the initiation site. For materials
showing a variety of fracture modes, the fracture modes observed at the initiation sites are
consistent with those observed in larger specimens. Where data are available, the stress and
strain conditions at the initiation sites are also found to be consistent in mini-C(T) and larger
specimens. These observations support the thesis that toughness measurements made on
mini-C(T) specimens reflect the same material characteristics and failure mechanisms as
those made on larger specimens.

Permalink: https://www.hzdr.de/publications/Publ-39435


Multiphase Python Repository by HZDR

Schlegel, F.; Hänsch, S.; Krull, B.; Lehnigk, R.; Meller, R.

Abstract

The python package provides several routines and scripts required to operate the code and cases repositories containing additional code and set-ups for the open-source software released by the OpenFOAM Foundation. This includes among others utilities for pre- and post-processing of simulation cases, utilities to launch virtual environments containing the source code, and utilities to operate the continuous integration and continuous development environment in a self-hosted Gitlab instance.

Keywords: Python; Numerical Simulations; Post-Processing; Gitlab

Downloads

Permalink: https://www.hzdr.de/publications/Publ-39434


Nuclear spin polarization in SiC using spin-3/2 centers at room temperature in the Earth's magnetic field

Anisimov, A.

Abstract

Nuclear spins are considered as a very promising quantum system for quantum information processing and sensing. Due to their very long spin coherence time, they are a key component of spin-based quantum registers. Nuclear spin hyperpolarization can enhance the signal intensities in magnetic resonance imaging by several orders of magnitude allowing detection of small chemical shifts and analysis of single cells. Due to the small value of the nuclear magneton, an effective way to initialize nuclear spins is first to polarize electron spins using optical excitation and then to transfer this polarization to the nuclear spin via the hyperfine interaction (HFI). Dynamic nuclear polarization (DNP) has been demonstrated in a variety of materials, including GaAs [1], diamond [2] and silicon carbide (SiC) [3].
Coupled electron-nuclear spins represent a promising quantum system, where the optically induced electron spin polarization can be dynamically transferred to nuclear spins via the hyperfine interaction. Most experiments on DNP are performed at cryogenic temperatures and/or in moderate external magnetic fields, the latter approach being very sensitive to the magnetic field orientation. Here, we demonstrate that the 29Si nuclear spins in SiC can be efficiently polarized at room temperature even in the Earth’s magnetic field. We exploit the asymmetric splitting of the optically detected magnetic resonance (ODMR) lines inherent to half-integer S = 3/2 electron spins, such that certain transitions involving 29Si nuclei can be clearly separated and selectively addressed using two radiofrequency fields. As a model system, we use the V3 silicon vacancy (VSi) in 6H-SiC, which has the zero-filed splitting parameter comparable with the HFI constant. Our theoretical model considers DNP under optical excitation in combination with RF driving and agrees very well with the experimental data. These results provide a straightforward approach for controlling the nuclear spin under ambient conditions, and may be an important step toward realizing nuclear hyperpolarization for bioimaging and long nuclear spin memory for quantum networks.

Keywords: Quantum technology; Silicon carbide; Point defects; Optically detected magnetic resonance; Nuclear spin polarization

  • Lecture (Conference)
    816. WE-Heraeus-Seminar "Silicon Carbide: Classical and Quantum Technologies", 28.-31.07.2024, English, Germany

Permalink: https://www.hzdr.de/publications/Publ-39433


Research Software Policy Establishment at Helmholtz - Activities and Results

Schlauch, T.; Konrad, U.

Abstract

The Helmholtz Association is a pioneer in the establishment of research software guidelines and policies in the German research landscape. The roots go back to one of the first German RSE focused workshops, which took place in Dresden in 2016. Since then, the field of RSE has been successively expanded at various levels through the provision of training and support services, technical platforms and, last but not least, the development of guidelines and policies. In context of research data management, a similar process has been driven with a strong focus on research data policies and data management plans. Guidelines for software development are just as important in modern research, but have hardly been established to date.

The talk is a progress report on the activities and results that have been achieved in the Helmholtz Centers in recent years. We present concrete examples with facts, statistics and user experience reports. In addition, we also share our experiences on how to actively stimulate this process, for example, through awards and visible indicators.The policy implementation at Helmholtz is ongoing and is actively supported in regular Helmholtz-wide research software forums organized by the Helmholtz Incubator Platform HIFIS and the Task Group Research Software of the Helmholtz Open Science Working Group.

Keywords: Software; Policy; Data Science; Helmholtz

Involved research facilities

  • Data Center

Related publications

Permalink: https://www.hzdr.de/publications/Publ-39432


Data publication: Comparative analysis of tetravalent actinide Schiff base complexes: influence of donor and ligand backbone on molecular geometry and metal binding

Duckworth, T.; Gericke, R.; Kaden, P.; Köhler, L.; Näder, A.; März, J.; Patzschke, M.; Stumpf, T.; Schmidt, M.

Abstract

IR spectra NMR spectra QCC results SC-XRD results PCS cone calculations

Keywords: Actinides; Schiff base; paramagnetic NMR; Coordination Chemistry; X-ray diffraction

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-39431


Comparative analysis of tetravalent actinide Schiff base complexes: influence of donor and ligand backbone on molecular geometry and metal binding

Duckworth, T.; Gericke, R.; Kaden, P.; Köhler, L.; Näder, A.; März, J.; Patzschke, M.; Stumpf, T.; Schmidt, M.

Abstract

A series of isostructural early actinide AnIV complexes was synthesized in order to investigate the influence of a conjugated framework in the ligand backbone on An bonding. Therefore, the AnIV complexes [An(pyrophen)2] (An = Th, U, Np, and Pu) with the pure N donor ligand bis(2-pyrrolecarbonylaldehyde)-o-phenylenediamine referred to as pyrophen, were synthesized and characterized. Solid state analysis via single-crystal X-ray diffraction (SC-XRD) reveals two sets of ligands binding in an almost orthogonal arrangement to the actinide center. For the larger actinides Th and U, the coordination sphere allows for additional coordination by a solvent molecule. Nuclear magnetic resonance spectroscopy (NMR) studies show the presence of highly symmetrical complexes in solution in good agreement with the solvent-free solid structures. While SC-XRD suggests mainly ionic binding, an analysis of paramagnetic NMR contributions and quantum chemical bond analysis hint towards significant covalency in the U, Np, and Pu compounds. This series of An complexes allowed for a thorough structural and theoretical comparison of a conjugated system to a closely related N-donor ligand (pyren)[1], as well as to the mixed N,O Schiff base ligands salophen (conjugated) and salen (non-conjugated).

Keywords: Actinides; Schiff base; paramagnetic NMR; Coordination Chemistry; X-ray diffraction

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Permalink: https://www.hzdr.de/publications/Publ-39430


Improving Mineral Classification Using Multimodal Hyperspectral Point Cloud Data and Multi-Stream Neural Network

Rizaldy, A.; Afifi, A. J. M.; Ghamisi, P.; Gloaguen, R.

Abstract

In this paper, we leverage multimodal data to classify minerals using a multi-stream neural network. In a previous study on the Tinto dataset, which consisted of a 3D hyperspectral point cloud from the open-pit mine Corta Atalaya in Spain, we successfully identified mineral classes by employing various deep learning models. However, this prior work solely relied on hyperspectral data as input for the deep learning models. In this study, we aim to enhance accuracy by incorporating multimodal data, which includes hyperspectral images, RGB images, and a 3D point cloud. To achieve this, we have adopted a graph-based neural network, known for its efficiency in aggregating local information, based on our past observations where it consistently performed well across different hyperspectral sensors. Subsequently, we constructed a multi-stream neural network tailored to handle multimodality. Additionally, we employed a channel attention module on the hyperspectral stream to fully exploit the spectral information within the hyperspectral data. Through the integration of multimodal data and a multi-stream neural network, we achieved a notable improvement in mineral classification accuracy: 19.2%, 4.4%, and 5.6% on the LWIR, SWIR, and VNIR datasets, respectively.

Keywords: mineral classification; geology; multimodal; hyperspectral; point cloud; deep learning; graph-CNN; hyperlouds; data fusion; multi-stream; machine learning

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Permalink: https://www.hzdr.de/publications/Publ-39429


Channel Attention Module for Segmentation of 3D Hyperspectral Point Clouds in Geological Applications

Rizaldy, A.; Ghamisi, P.; Gloaguen, R.

Abstract

We develop a Transformer-based model enhanced with a Channel Attention Module (CAM) to capture the inter-channel dependencies in 3D hyperspectral point cloud data for geological applications. We hypothesize that specific channels of hyperspectral data correspond to distinct mineral types, and therefore, exploiting the relationships among these channels is beneficial for our analysis. We evaluate our method using the newly released Tinto dataset, which consists of 3D hyperspectral point clouds featuring three different spectral ranges: LongWave Infrared (LWIR), ShortWave Infrared (SWIR), and Visible-Near Infrared (VNIR).We explore four different CAMs from various networks—SENet, ECANet, CBAM, and DANet—and successfully integrate them into a CNN-based model to enhance feature representation. We specifically tailor the channel attention to our use of 3D hyperspectral point cloud data. Our experiments demonstrate significant improvements in performance after incorporating the CAM into our backbone model, which draws inspiration from the Point Cloud Transformer architecture and Vector Self-Attention mechanism. These results highlight the potential for further research into enhancing classification accuracy using hyperspectral data in geological applications. The code will be released on https://github.com/aldinorizaldy/CAM-Transformer.

Keywords: Machine learning; Deep learning; Channel attention; Transformer; 3D Point cloud; Hyperspectral; Geology

Permalink: https://www.hzdr.de/publications/Publ-39428


Transformer-Based Models for Hyperspectral Point Clouds Segmentation

Rizaldy, A.; Afifi, A. J. M.; Ghamisi, P.; Gloaguen, R.

Abstract

Transformer-based models have achieved state-of-the-art results in point cloud segmentation. However, their evaluation has been limited to benchmark data with natural objects. In this study, we present the first investigation of Transformers for hyperspectral point clouds, comparing different attention modules. We utilize the Tinto dataset, which provides extensive hyperspectral features for geological applications, offering diverse benchmarking settings. Our experiments demonstrate that the Transformer with vector attention surpasses the commonly-used dot-product scalar attention. Moreover, this model achieves significantly higher accuracy scores than the well-known point cloud models, PointNet and PointNet++, across three hyperspectral sensors.

Keywords: Machine learning; Deep learning; Point cloud; Hyperspectral; Transformer; Attention; Classification

Permalink: https://www.hzdr.de/publications/Publ-39427


Identifying magnetic phases in chemically ordered and disordered FeAl thin films

Zarzycki, A.; Anwar, S.; Bali, R.; Potzger, K.; Krupinski, M.; Marszalek, M.

Abstract

Partial disordering of Fe60Al40 thin films was achieved during neon ion irradiation through nanosphere shadow masks or by adjusting the ion energy for near-surface penetration only. Both approaches lead to adjacent chemically disordered and ordered areas. The magnetic behaviour of the films reveals a low-magnetization and high-coercive chemically ordered phase (non-irradiated ferromagnetic area, NIFM), as well as a high-magnetization and low-coercive chemically disordered phase (irradiated ferromagnetic area, IMF). It was shown that the modulated films of coexisting magnetic phases do not lead to an exchange coupling in most cases. Evidence for exchange-spring behaviour, however, was found. Moreover, both magneto-structural phases show at low temperatures spin-glass like properties.

Keywords: Magnetism; Ion irradiation; Nano patterning

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-39426


Evaluation data set for the GravelSensor

Bieberle, A.; Schleicher, E.
DataCollector: Bieberle, André; RelatedPerson: Schleicher, Eckhard; Producer: Tschofen, Martin; Producer: Loeschau, Martin

Abstract

In this study, we used gamma-ray computed tomography (GammaCT) as reference measurement system to evaluate a novel, non-destructive, smart gravel sensor that is based on the well-known wire-mesh sensor. Various sediment fillings with different infiltrating particle sizes are applied to the gravel sensor and the generated particle holdup is locally determined with both measurement systems simultaneously.

Keywords: Wire-mesh sensor; Gravel sensor; Gamma-ray computed tomography

Involved research facilities

  • TOPFLOW Facility

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Permalink: https://www.hzdr.de/publications/Publ-39425


Anisotropic magnetoresistance in altermagnetic MnTe

Gonzalez Betancourt, R. D.; Zubáč, J.; Geishendorf, K.; Ritzinger, P.; Růžičková, B.; Kotte, T.; Železný, J.; Olejník, O.; Springholz, G.; Büchner, B.; Thomas, A.; Výborný, K.; Jungwirth, T.; Reichlová, H.; Kriegner, D.

Abstract

Recently, MnTe was established as an altermagnetic material that hosts spin-polarized electronic bands as well as anomalous transport effects like the anomalous Hall effect. In addition to these effects arising from altermagnetism, MnTe also hosts other magnetoresistance effects. Here, we study the manipulation of the magnetic order by an applied magnetic field and its impact on the electrical resistivity. In particular, we establish which components of anisotropic magnetoresistance are present when the magnetic order is rotated within the hexagonal basal plane. Our experimental results, which are in agreement with our symmetry analysis of the magnetotransport components, showcase the existence of an anisotropic magnetoresistance linked to both the relative orientation of current and magnetic order, as well as crystal and magnetic order. Altermagnetism is manifested as a three-fold component in the transverse magnetoresistance which arises due to the anomalous Hall effect.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-39424


Sharp quantum phase transition in the frustrated spin-1/2 Ising chain antiferromagnet CaCoV2O7

Isha; Bera, A. K.; Kaur, G.; Stock, C.; Chakraborty, K.; Puphal, P.; Isobe, M.; Küster, K.; Skourski, Y.; Bhaskaran, L.; Zvyagin, S.; Luther, S.; Gronemann, J.; Kühne, H.; Salazar Mejia, C.; Pregelj, M.; Hansen, T. C.; Kaushik, S. D.; Voneshen, D.; Kulkarni, R.; Lalla, N. P.; Yusuf, S. M.; Thamizhavel, A.; Yogi, A. K.

Abstract

We report on a quantum critical behavior in the quasi-1D spin-1/2 zigzag frustrated chain antiferromagnet CaCoV2O7, induced by an applied magnetic field. Below TN = 3.3 K our zero-field neutron diffraction studies revealed the up-up-down-down spin structure, stabilized by an order-by-disorder phenomenon. At base temperature, the magnetic order is suppressed by an applied magnetic field (B), inducing a transition into a quantum paramagnetic state at Bc = 3 T, as revealed by both neutron diffraction and ESR data. The transition exhibits an unusually sharp phase boundary with the critical exponent φ = 0.164(3) ≈ 1/6, in contrast to the earlier experimental observations for uniform spin-1/2 chain systems. Such a sharp QPT is anticipated due to a rare combination of spin-orbit coupling and competing NN and NNN exchange interactions J1 and J2 of the zigzag spin chain.

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-39423


Data publication: Dynamic exchange–correlation effects in the strongly coupled electron liquid

Dornheim, T.

Abstract

This repository contains all raw data pertaining to the figures in the publication "Dynamic exchange–correlation effects in the strongly coupled electron liquid", arXiv:2405.08480 Generally, files contain gnuplot formatted output using units shown in the figures. Exceptions are given by "Fig2.txt, Fig11_rs4.txt, Fig13_*.txt", where the relevant columns are given by: #1: q in a_B^{-1}; #2: integer Matsubara frequency index; #3: density response, not normalised by particle number

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Permalink: https://www.hzdr.de/publications/Publ-39422


Prognostic value of total tumor burden measured by FDG-PET in patients with locally advanced non-small-cell lung cancer

Hofheinz, F.; Fitis, E.; Nikulin, P.; van den Hoff, J.; Zschaeck, S.

Abstract

MOTIVATION:

Patients with locally advanced non-small-cell lung cancer (NSCLC) have
a high risk of developing distant metastases. It was shown that
immunotherapy after radiochemotherapy significantly improves the
prognosis. Therefore, biomarkers to identify such patients are
urgently needed. Here, we investigated the prognostic utility of total
tumor burden (TTB) in NSCLC for prediction of distant metastases.

METHODS:

Altogether, 165 patients (65+/-9)y, 100m) with newly diagnosed NSCLC
were included. All patients received FDG-PET/CT prior to definitive
radiochemotherapy. In the PET images, the metabolically active volume
(MTV) of the primary tumor and of all FDG avid lymph nodes was
delineated with an adaptive threshold method. TTB was computed as the
cumulative volume of primary tumor and lymph nodes. Survival analysis
with respect to freedom from distant metastases (FFDM) was performed.
RESULTS:

Survival analysis revealed MTV and TTB as prognostic factors for FFDM
(P=0.004 and P<0.001, respectively). Hazard ratio (HR) for TTB was
significantly higher than HR for MTV (1.9 vs. 2.5, P=0.007).

CONCLUSIONS:

In the investigated group of patients, the inclusion of lymph nodes
into MTV computation significantly increased the prognostic value of
FDG-PET. Further investigations are necessary to confirm these
preliminary results.

Involved research facilities

  • PET-Center
  • Poster
    62. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 11.-13.04.2024, Leipzig, Deutschland
    DOI: 10.1055/s-0044-1782483

Permalink: https://www.hzdr.de/publications/Publ-39421


68Ga-labeled fibroblast activation protein inhibitor (FAPI) PET/CT for locally advanced or recurrent pancreatic cancer staging and restaging after chemoradiotherapy

Metzger, G.; Bayerl, C.; Rogasch, J.; Furth, C.; Wetz, C.; Beck, M.; Mehrhof, F.; Amthauer, H.; Ghadjar, P.; Neumann, C.; Pelzer, U.; Zips, D.; Hofheinz, F.; Grabowski, J.; Schatka, I.; Zschaeck, S.

Abstract

Purpose: 68Ga-labeled fibroblast activation protein inhibitor (FAPI) is a novel PET tracer with great potential for staging pancreatic cancer. Data on locally advanced or recurrent disease is sparse, especially on tracer uptake before and after high dose chemoradiotherapy (CRT). The aim of this study was to evaluate [68Ga]Ga-FAPI-46 PET/CT staging in this setting.

Methods: Twenty-seven patients with locally recurrent or locally advanced pancreatic adenocarcinoma (LRPAC n = 15, LAPAC n = 12) in stable disease or partial remission after chemotherapy underwent FAPI PET/CT and received consolidation CRT in stage M0 with follow-up FAPI PET/CT every three months until systemic progression. Quantitative PET parameters SUVmax, SUVmean, FAPI-derived tumor volume and total lesion FAPI-uptake were measured in baseline and follow-up PET/CT scans. Contrast-enhanced CT (ceCT) and PET/CT data were evaluated blinded and staged according to TNM classification.

Results: FAPI PET/CT modified staging compared to ceCT alone in 23 of 27 patients in baseline, resulting in major treatment alterations in 52% of all patients (30%: target volume adjustment due to N downstaging, 15%: switch to palliative systemic chemotherapy only due to diffuse metastases, 7%: abortion of radiotherapy due to other reasons). Regarding follow-up scans, major treatment alterations after performing FAPI PET/CT were noted in eleven of 24 follow-up scans (46%) with switch to systemic chemotherapy or best supportive care due to M upstaging and ablative radiotherapy of distant lymph node and oligometastasis. Unexpectedly, in more than 90 % of the follow-up scans, radiotherapy did not induce local fibrosis related FAPI uptake.

During the first follow-up, all quantitative PET metrics decreased, and irradiated lesions showed significantly lower FAPI uptake in locally controlled disease (SUVmax p = 0.047, SUVmean p = 0.0092) compared to local failure.

Conclusion: Compared to ceCT, FAPI PET/CT led to major therapeutic alterations in patients with LRPAC and LAPAC prior to and after radiotherapy, which might help identify patients benefiting from adjustments in every treatment stage. FAPI PET/CT should be considered a useful diagnostic tool in LRPAC or LAPAC before and after CRT.

Keywords: locally recurrent pancreatic adenocarcinoma; locally advanced pancreatic adenocarcinoma; fibroblast activation protein inhibitor; positron emission tomography; radiochemotherapy

Involved research facilities

  • PET-Center

Permalink: https://www.hzdr.de/publications/Publ-39420


Quantitative PSMA-PET parameters in localized prostate cancer: prognostic and potential predictive value

Bela Andela, S.; Amthauer, H.; Furth, C.; Rogasch, J.; Beck, M.; Mehrhof, F.; Ghadjar, P.; van den Hoff, J.; Klatte, T.; Tahbaz, R.; Zips, D.; Hofheinz, F.; Zschaeck, S.

Abstract

Background

PSMA-PET is increasingly used for staging prostate cancer (PCA) patients. However, it is not clear if quantitative imaging parameters of positron emission tomography (PET) have an impact on disease progression and are thus important for the prognosis of localized PCA.

Methods

This is a monocenter retrospective analysis of 86 consecutive patients with localized intermediate or high-risk PCA and PSMA-PET before treatment The quantitative PET parameters maximum standardized uptake value (SUVmax), tumor asphericity (ASP), PSMA tumor volume (PSMA-TV), and PSMA total lesion uptake (PSMA-TLU = PSMA-TV × SUVmean) were assessed for their prognostic significance in patients with radiotherapy or surgery. Cox regression analyses were performed for biochemical recurrence-free survival, overall survival (OS), local control, and loco-regional control (LRC).

Results

67% of patients had high-risk disease, 51 patients were treated with radiotherapy, and 35 with surgery. Analysis of metric PET parameters in the whole cohort revealed a significant association of PSMA-TV (p = 0.003), PSMA-TLU (p = 0.004), and ASP (p < 0.001) with OS. Upon binarization of PET parameters, several other parameters showed a significant association with clinical outcome. When analyzing high-risk patients according to the primary treatment approach, a previously published cut-off for SUVmax (8.6) showed a significant association with LRC in surgically treated (p = 0.048), but not in primary irradiated (p = 0.34) patients. In addition, PSMA-TLU (p = 0.016) seemed to be a very promising biomarker to stratify surgical patients.

Conclusion

Our data confirm one previous publication on the prognostic impact of SUVmax in surgically treated patients with high-risk PCA. Our exploratory analysis indicates that PSMA-TLU might be even better suited. The missing association with primary irradiated patients needs prospective validation with a larger sample size to conclude a predictive potential.

Keywords: PSMA; Positron emission tomography; Prostate cancer; Prostate-specific membrane antigen; Quantitative PET parameters; Prognostic value

Involved research facilities

  • PET-Center

Permalink: https://www.hzdr.de/publications/Publ-39419


Surface-symmetry-driven Dzyaloshinskii-Moriya interaction in collinear anitferromagnets

Pylypovskyi, O.; Weber, S.; Makushko, P.; Veremchuk, I.; Spaldin, N.; Makarov, D.

Abstract

Magnetic properties of the crystal are determined by its magnetic symmetry group. A large number of antiferromagnets (AFMs) provides a variety of such symmetry-driven features as magnetoelectricity, spin canting, staggered spin-orbit torques and others [1]. Recent advances in experimental techniques, such as magnetotransport [2] or Nitrogen vacancy magnetometry [3] open a possibility of exploring the surface properties of AFMs. Still, many properties of AFM surfaces remain to be understood.

Here, we study the nominally compensated side crystallographic cuts (m and a planes) of Cr2O3. We show that a finite magnetic moment per unit area at these surfaces is caused by the surface magnetic point symmetry of these cuts and can be explained in terms of the homogeneous Dzyaloshinskii-Moriya interaction (DMI) corresponding to this symmetry. We found, that the m-plane Cr2O3 surface behaves as a canted ferrimagnet with finite out-of-surface magnetization caused by the spin canting and in-plane magnetization along the c axis due to inequivalent magnetic sublattices. The a-plane Cr2O3 surface behaves as a canted 4-lattice sublattice AFM with out-of-plane magnetization [4].

By means of ab initio calculations, we study the change of the magnetic properties from the surface to bulk and quantify the surface-symmetry-driven DMI at Cr2O3 surface cuts to be of order of 1 mJ/m2. The respective spin canting is about 0.5°. The finite out-of-plane magnetization is detected by means of magnetotransport. We found the non-trivial dependency of the magnetotransport response on temperature, which indicates the thermodynamic properties of the surface-symmetry-driven DMI due to contributions of the single-ion anisotropy and antisymmetric exchange [4]. Our findings could be further applied for studies of the surface magnetic responses in other types of AFMs [5] and be used for the electric readout of the collinear AFM states.

Keywords: Cr2O3; surface states; DMI

  • Lecture (Conference)
    CMD31, 02.-06.09.2024, Braga, Portugal

Permalink: https://www.hzdr.de/publications/Publ-39418


Magnetic textures in easy-axis antiferromagnets

Pylypovskyi, O.

Abstract

The spin degree of freedom in magnetically ordered materials is an important aspect for a variety of research directions. Antiferromagnets represent a broad class of systems with compensated or almost compensated net magnetization. On one side, it is a factor in the complications of their experimental investigation. However, on the other side, they offer unique features on ultrafast dynamics, strong robustness regarding external magnetic fields and delicate symmetry-driven phenomena in spin torques and multiferroicity. Specific research attention is paid to the properties of antiferromagnetic solitons as potential information carriers and the surface properties at which the readout of the magnetic state is performed. Here, we focus on the seminal magnetoelectric antiferromagnet Cr2O3 (chromia) with the easy-axis magnetic anisotropy.

In bulk single crystal chromia, the multidomain state is not favorable due to thermodynamic reasons, thus the stabilization of domain walls is possible on the defects. In particular, the litographically partterned surface topography of the sample can serve as the pinning landscape for the domain wall. The spatial inhomogeneity of this landscape allows to uncover the mechanical properties of the magnetic textures such as elastic deformation of the domain wall plane governed by the exchange boundary conditions [1]. Extension of this model onto chiral antiferromagnets with an inhomogeneous Dzyaloshinskii-Moriya interaction (DMI) shows that the domain walls and skyrmions possess a substantial modification of their shape approaching surface and side faces of the sample. These modifications limit the minimal size of racetracks to keep the bulk-like properties of magnetic solitons [2].

The surface of an antiferromagnet itself can substantially change its magnetic state. Chromia possesses two nominally compensated high-symmetry planes with an experimental evidence of a finite magnetization. The latter can be understood in terms of the surface magnetic symmetry group which supports a homogeneous DMI and can even change the bulk collinear antiferromagnetic ordering to a canted ferrimagnetic one [3].

In contrast to bulk, the chromia thin films are commonly in the multidomain state, which is determined by their granular structure. The domain wall pinning at the defects depends on the defect properties. Therefore, the visual analysis of the domain picture obtained, e.g., via Nitrogen vacancy magnetometry can be used as a source of quantification of the inter-grain coupling in the thin film [4] and, even quantification of such exotic phenomena like thermally driven flexomagnetism [5].

Keywords: Antiferromagnets; Cr2O3; magnetic textures

  • Lecture (others)
    WPI-SKCM seminar, 25.07.2024, Hiroshima, Japan

Permalink: https://www.hzdr.de/publications/Publ-39417


Magnetic textures in bulk and thin film Cr2O3

Pylypovskyi, O.

Abstract

The spin degree of freedom in magnetically ordered materials is an important aspect for a variety of research directions. Antiferromagnets represent a broad class of systems with compensated or almost compensated net magnetization. On one side, it is a factor in the complications of their experimental investigation. However, on the other side, they offer unique features on ultrafast dynamics, strong robustness regarding external magnetic fields and delicate symmetry-driven phenomena in spin torques and multiferroicity. Specific research attention is paid to the properties of antiferromagnetic solitons as potential information carriers and the surface properties at which the readout of the magnetic state is performed. Here, we focus on the seminal magnetoelectric antiferromagnet Cr2O3 (chromia) with the easy-axis magnetic anisotropy.

In bulk single crystal chromia, the multidomain state is not favorable due to thermodynamic reasons, thus the stabilization of domain walls is possible on the defects. In particular, the litographically partterned surface topography of the sample can serve as the pinning landscape for the domain wall. The spatial inhomogeneity of this landscape allows to uncover the mechanical properties of the magnetic textures such as elastic deformation of the domain wall plane governed by the exchange boundary conditions [1]. In contrast, the chromia thin films are commonly in the multidomain state, which is determined by their granular structure. The domain wall pinning at the defects depends on the defect properties. Therefore, the visual analysis of the domain picture obtained, e.g., via Nitrogen vacancy magnetometry can be used as a source of quantification of the inter-grain coupling in the thin film [2]. Furthermore, in the case of the high-quality chromia samples epitaxially grown at sapphire substrate, the presence of domain walls allows to reveal a new temperature-driven source of the flexomagnetism in thin antiferromagnetic films [3].

Even in absence of specific processing like litography or design of exchange bias multilayers, the surface of an antiferromagnet can alter its magnetic state by its specific magnetic symmetry. Chromia possesses two nominally compensated high-symmetry planes with an experimental evidence of finite magnetization. It can be understood by the surface magnetic point symmetry group, which renders the m and a planes of chromia to be canted ferrimagnet and antiferromagnet, respectively [4].

Keywords: Cr2O3; domain walls; surface; DMI

  • Lecture (others)
    Seminar in Osaka University, 22.07.2024, Osaka, Japan

Permalink: https://www.hzdr.de/publications/Publ-39416


Data publication: Hot-Electron Dynamics in a Semiconductor Nanowire under Intense THz Excitation

Luferau, A.; Obst, M.; Winnerl, S.; Pashkin, O.; Kehr, S. C.; Dimakis, E.; Kaps, F.; Hatem, O.; Mavridou, K.; Eng, L. M.; Helm, M.

Abstract

Python code for data processing and raw data

Keywords: Semiconductor; Nanowires; THz; s-SNOM; Near-field spectroscopy; Pump-probe spectroscopy

Involved research facilities

  • F-ELBE

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Permalink: https://www.hzdr.de/publications/Publ-39415


Hot-Electron Dynamics in a Semiconductor Nanowire under Intense THz Excitation

Luferau, A.; Obst, M.; Winnerl, S.; Pashkin, O.; Kehr, S. C.; Dimakis, E.; Kaps, F.; Hatem, O.; Mavridou, K.; Eng, L. M.; Helm, M.

Abstract

We report terahertz (THz)-pump/mid-infrared probe near-field studies on Si-doped GaAs–InGaAs core–shell nanowires utilizing THz radiation from the free-electron laser FELBE. Upon THz excitation of free carriers, we observe a red shift of the plasma resonance in both amplitude and phase spectra, which we attribute to the heating of electrons in the conduction band. The simulation of heated electron distributions anticipates a significant electron population in both the L- and X-valleys. The two-temperature model is utilized for quantitative analysis of the dynamics of the electron gas temperature under THz pumping at various power levels.

Keywords: Semiconductor; Nanowires; THz; s-SNOM; Near-field spectroscopy; Pump-probe spectroscopy

Involved research facilities

  • F-ELBE

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Permalink: https://www.hzdr.de/publications/Publ-39413


Magnon-phonon Fermi resonance in antiferromagnetic CoF2

Metzger, T.; Grishunin, K.; Reinhoffer, C.; Dubrovin, R.; Arshad, A.; Ilyakov, I.; de Oliveira, T.; Ponomaryov, O.; Deinert, J.-C.; Kovalev, S.; Pisarev, R.; Katsnelson, M. I.; Ivanov, B.; van Loosdrecht, P. H. M.; Kimel, A.; Mashkovich, E.

Abstract

Understanding spin-lattice interactions in antiferromagnets is a critical element of the fields of antiferromagnetic spintronics and magnonics. Recently, coherent nonlinear phonon dynamics mediated by a magnon state were discovered in an antiferromagnet. Here, we suggest that a strongly coupled two-magnon-one phonon state in this prototypical system opens a novel pathway to coherently control magnon-phonon dynamics. Utilizing intense narrow-band terahertz (THz) pulses and tunable magnetic fields up to μ_0 H_ext = 7 T, we experimentally realize the conditions of magnon-phonon Fermi resonance in antiferromagnetic CoF2. These conditions imply that both the spin and the lattice anharmonicities harvest energy from the transfer between the subsystems if the magnon eigenfrequency f_m is half the frequency of the phonon 2f_m = f_ph. Performing THz pump-infrared probe spectroscopy in conjunction with simulations, we explore the coupled magnon-phonon dynamics in the vicinity of the Fermi-resonance and reveal the corresponding fingerprints of nonlinear interaction facilitating energy exchange between these subsystems.

Keywords: Terahertz; Magnon; Phonon; Magnon-phonon Resonance; Fermi resonance; Spintronics; Magnetism; Ultrafast dynamics; Antiferromagnetism

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Permalink: https://www.hzdr.de/publications/Publ-39412


Simulation and experimental benchmarking of a proton pencil beam scanning nozzle for development of MRI-guided proton therapy

Oborn, B. M.; Semioshkina, E.; van der Kraaij, E.; Hoffmann, A. L.

Abstract

Background: MR-integrated proton therapy is under development. It consists
of the unique challenge of integrating a proton pencil beam scanning (PBS)
beam line nozzle with an magnetic resonance imaging (MRI) scanner.The magnetic
interaction between these two components is deemed high risk as the
MR images can be degraded if there is cross-talk during beam delivery and
image acquisition.
Purpose: To create and benchmark a self -consistent proton PBS nozzle model
for empowering the next stages of MR-integrated proton therapy development,
namely exploring and de-risking complete integrated prototype system designs
including magnetic shielding of the PBS nozzle.
Materials and Methods: Magnetic field (COMSOL Multiphysics) and radiation
transport (Geant4) models of a proton PBS nozzle located at OncoRay (Dresden,
Germany) were developed according to the manufacturers specifications.
Geant4 simulations of the PBS process were performed by using magnetic field
data generated by the COMSOL Multiphysics simulations. In total 315 spots
were simulated which consisted of a 40 × 30cm2 scan pattern with 5 cm spot
spacings and for proton energies of 70, 100, 150, 200, and 220 MeV. Analysis
of the simulated deflection at the beam isocenter plane was performed to
determine the self -consistency of the model. The magnetic fringe field from a
sub selection of 24 of the 315 spot simulations were directly compared with high
precision magnetometer measurements.These focused on the maximum scanning
setting of ± 20 cm beam deflection as generated from the second scanning
magnet in the PBS for a proton beam energy of 220 MeV. Locations along the
beam line central axis (CAX) were measured at beam isocenter and downstream
of 22, 47, 72, 97, and 122 cm. Horizontal off -axis positions were measured
at 22 cm downstream of isocenter (± 50,± 100,and ± 150 cm from CAX).
Results: The proton PBS simulations had good spatial agreement to the theoretical
values in all 315 spots examined at the beam line isocenter plane
(0–2.9 mm differences or within 1.5 % of the local spot deflection amount).
Careful analysis of the experimental measurements were able to isolate
the changes in magnetic fields due solely to the scanning magnet contribution,
and showed 1.9 ± 1.2 uT–9.4 ± 1.2 uT changes over the range
of measurement locations. Direct comparison with the equivalent simulations
matched within the measurement apparatus and setup uncertainty in all but
one measurement point.
Conclusions: For the first time a robust, accurate and self -consistent model
of a proton PBS nozzle assembly has been created and successfully
benchmarked for the purposes of advancing MR-integrated proton therapy
research. The model will enable confidence in further simulation based work
on fully integrated designs including MRI scanners and PBS nozzle magnetic
shielding in order to de-risk and realize the full potential of MR-integrated proton
therapy.

Keywords: MRI guided; pencil beam scanning; proton therapy

Involved research facilities

  • OncoRay

Permalink: https://www.hzdr.de/publications/Publ-39411


Blood-brain barrier water permeability across the adult lifespan: A multi-echo ASL study

Padrela, B. E.; Slivka, M.; Sneve, M. H.; Garrido, P. F.; Dijsselhof, M. B. J.; Hageman, T.; Geier, O.; Grydeland, H.; Mahroo, A.; Kuijer, J. P. A.; Konstandin, S.; Eickel, K.; Barkhof, F.; Günther, M.; Walhovd, K. B.; Fjell, A. M.; Mutsaerts, H. J. M. M.; Petr, J.

Abstract

An emerging biomarker of blood-brain barrier (BBB) permeability is the time of exchange (Tex) of water from the blood to tissue, as measured by multi-echo arterial spin labeling (ASL) MRI. This new non-invasive sequence, already tested in mice, has recently been adapted to humans and optimized for clinical scanning time. In this study, we studied the normal variability of Tex over age and sex, which needs to be established as a reference for studying changes in neurological disease. We evaluated Tex and cerebral blood flow (CBF) in 209 healthy adults between 26 and 87 years, over age and sex, using general linear models in gray matter, white matter, and regionally in cerebral lobes. Results demonstrated that both gray matter (GM) and white matter (WM) BBB permeability was higher with higher age (Tex lower by 0.42 ms per year in GM, p=0.025, and by 0.49 ms in WM, p=0.009, corrected for sex), with the largest Tex difference in the frontal lobes (0.64 ms decrease per year, p=0.011). CBF was lower with higher age in the GM (0.72 ml/min/100g per year, p<0.001). The CBF findings of this study are in line with previous studies, demonstrating the validity of the new sequence. The BBB water permeability variation over age and sex described in this study provides a reference for future BBB research.

Involved research facilities

  • PET-Center

Permalink: https://www.hzdr.de/publications/Publ-39410


Multiscale Multiphase Flow Modelling - AIAD & GENTOP

Höhne, T.

Abstract

Optimization of large-scale multiphase processes requires adequate and efficient CFD-tools.

Large scales flow behavior depend on sub-grid physical phenomena that have to be described by closure models.
Different models necessary for dispersed particles and separated continuous phases (interfacial drag etc.)
Applications: Flow patterns in horizontal pipes, separation processes in rectification columns, stirred tank reactors etc.

Keywords: AIAD; GENTOP; Two phase flow; CFD; stratified; Gas; Liquid

  • Lecture (Conference)
    20th Multiphase Flow Conference and Short Course Simulation, Experiment and Application, November 11 – 15, 2024, 11.-15.11.2024, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-39409


Metal recovery by bioionflotation

Chakankar, M. V.

Abstract

Industrial wastewaters are secondary sources of many critical and base metals. Recovering these metals from such waste streams helps in resource recycling and reduce the environmental burden. Low concentration of target metals and high concentration of unwanted metals makes such a recovery challenging. Ion flotation is a promising separation and recovery process in this regards. The use of various flotation agents is well documented, yet there is a high demand for new flotation agents. The new ion flotation agents need to be highly selective, efficient, and environmentally friendly. Microbial biomolecules are an attractive alternative and we are exploring various biomolecules in this regards. The critical metal complexing ability and interfacial properties of these biomolecules are unknown, which needs to be deciphered to fill the knowledge gap and develop the fundamental understanding required to develop the process and improve efficiency. This perception will allow to fully embrace the potential of novel bio-ion collectors in developing a highly synergistic process of bioionflotation for recovery of critical metals.

  • Invited lecture (Conferences)
    Guest Lecture, 08.07.2024, Pune, India

Permalink: https://www.hzdr.de/publications/Publ-39408


Biomolecules as green flotation reagents in bioionflotation process

Chakankar, M. V.; Pollmann, K.; Kutschke, S.; Rudolph, M.

Abstract

Industrial wastewaters are secondary sources of many critical and base metals. Recovering these metals from such waste streams helps in resource recycling and reduce the environmental burden. Low concentration of target metals and high concentration of unwanted metals makes such a recovery challenging. Ion flotation is a promising separation and recovery process in this regards. The use of various flotation agents is well documented, yet there is a high demand for new flotation agents. The new ion flotation agents need to be highly selective, efficient, and environmentally friendly. Microbial biomolecules are an attractive alternative and we are exploring various biomolecules in this regards. The critical metal complexing ability and interfacial properties of these biomolecules are unknown, which needs to be deciphered to fill the knowledge gap and develop the fundamental understanding required to develop the process and improve efficiency. This perception will allow to fully embrace the potential of novel bio-ion collectors in developing a highly synergistic process of bioionflotation for recovery of critical metals.

In this study, we provide an insight on the use of biosurfactants and amphiphilic siderophores as green flotation reagents with a focus on the dynamic surface tension, foamability and foam characterization as well as influence of metal ions on these properties followed by flotation studies for selective separation of metals. The results provide the basis for application of these biomolecules as green flotation reagents in bioionflotation for recovery of critical metals from wide range of secondary sources such as industrial wastewaters, leachates, mine waters, etc. Moreover, the resulting eco-friendly technology will boost resource efficiency, increase recycling rate, reduce waste, reduce critical metal dependency on non-EU countries and proliferate circular economy in EU.

  • Lecture (Conference)
    52nd Biennial Assembly of the German Colloid Society, 30.09.-02.10.2024, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-39407


The outstanding properties of magnetotactic bacteria for remediation purposes of uranium contaminated wastewater

Krawczyk-Bärsch, E.; Ramtke, J.; Drobot, B.; Raff, J.

Abstract

Mining activities and the processing of ores have left a legacy of contamination of the environment. Soluble uranium(VI) species can migrate into surrounding aquifers and soils, thus represent a significant human health risk. Conventional technologies based on physicochemical treatments are traditionally used to remediate these contaminated environments. However, these approaches are cost-intensive and ineffective for low uranium concentrations. A promising method to support and outperform chemical treatments is the bioremediation with the help of magnetotactic bacteria, like Magnetospirillum magneticum AMB-1. A combination of transmission electron and fluorescence microscopy as well as various spectroscopic techniques, e.g. cryo-time resolved laser-induced fluorescence (TRLFS) and in-situ attenuated total reflection Fourier-transform infrared (ATR FT-IR) spectroscopy, revealed that Magnetospirillum magneticum AMB-1 cells are able to bind high amounts of uranium. Already in the first hours of exposure uranium is bound in the cell wall over a wide pH range showing a stable immobilization of uranium. Parallel factor analysis of the TRLFS spectra highlights that peptidoglycan, as one of the cell wall´s ligands, plays the main role in absorbing uranium. The formation of three characteristic species were proved. This insights about magnetotactic bacteria are new and unexpected in this type of Gram-negative bacteria.
A further outstanding feature is the formation of nanoscopic magnetic crystals within the cell of magnetotactic bacteria, which makes them suitable for simple mechanical separation processes. In combination with the magnetic properties of these bacteria, a simple technical water purification process could be realized not only for uranium, but probably also for other heavy metals with the objective of potential industrial applications in the field of microbiological purification of water.

Keywords: Uranium; Bacteria; Sorption; Remediation

  • Lecture (others)
    48th European Radiation Research Society Meeting, 10.-13.09.2024, Aveiro, Portugal

Permalink: https://www.hzdr.de/publications/Publ-39406


Bioionflotation: A promising approach for recycling of metals from industrial wastewaters

Chakankar, M. V.; Pollmann, K.; Kutschke, S.; Rudolph, M.

Abstract

Ion flotation process offers a sustainable way to separate and recycle critical metals from industrial wastewaters that often have low concentrations of target metals. There is a high demand for new flotation reagents which are preferentially environmentally friendly. Microbial biomolecules are an attractive alternative and we are exploring various biomolecules in this regards. The use of these biomolecules as flotation reagents in the ion flotation process can be termed as ‘bioionflotation’. This biotechnological approach for metal recovery from low concentrated waters is still dawning and more research is required to improve the selectivity and process efficiency. In this work, marinobactin (a suite of amphiphilic siderophores) was investigated as a flotation reagent for the separation of Gallium (Ga) from synthetic solutions. Amphiphilic nature of these siderophores and metal complexation ability make them an interesting molecule for an application in the flotation process. Single metal flotation test suggested the Ga recovery and marinobactin-Ga complexation in the collected concentrates was confirmed by HPLC. Further, effects of various operating parameters on the metal recovery and selectivity were studied. The flotation results of the mixed metal solutions (containing Ga and As at 1 mM concentration), showed 88% of Ga recovery and 11% of As recovery, at 0.25 mM marinobactin concentration at pH 4 and air flow rate of 20 ml/min. These results provide the basis to fully embrace the potential of novel bio-ion collectors in developing a highly synergistic process of bioionflotation for recovery of critical metals from low concentrated wastewater.

  • Lecture (Conference)
    GeoSaxonia 2024, 23.-26.09.2024, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-39405


Biodegradation of graphene by environmental microorganisms

Jain, P.; Gerstner, T.; Harter, S. D.; Matys, S.; Lehmann, F.; Chakankar, M. V.; Pollmann, K.

Abstract

Graphene and its derivatives such as graphene oxide (GO) are looked upon as the next wonder material due to its unique physiochemical properties - transparency, density, electric and thermal conductivity, elasticity, flexibility, hardness, and capacity to generate chemical reactions with other substances. This has allowed potential applications of graphene in electronics, aviation, medicine, and much more. The findings were of such high impact that the discovery of the material also paved the way for the Nobel Prize. GO is particularly popular among graphene-based materials (GBMs) for its easier and inexpensive manufacture. The consumption of GBM is expected to increase in the future due to its integration into various technical products. In this context, we acknowledge the useful properties of new material, but we should also consider life cycle analysis, the fate, and safety assessment of the environment and human health of GBM before over-exploitation. The over-exploitation of wonder material of the 19th century, plastic and now dealing with hazardous effects, should be the case in point. Thus, the biodegradation of GBMs is a relevant topic to study further for maximizing the societal beneficiary use of this novel material.
Many environmental bacterial strains have been isolated and characterized from hydrocarbon and metal-contaminated sites. These bacterial strains seem to thrive in toxic environments. We hoped to utilize such strains to break down GBMs and transform them into less harmful biodegradable by-products.

Keywords: Graphene; Sphingobium

  • Lecture (Conference)
    International Biodeterioration and Biodegradation Symposium, 09.-12.09.2024, Berlin, Germany

Permalink: https://www.hzdr.de/publications/Publ-39404


E/valuation of Sustainability in Basic Research—Insights from an interdisciplinary research initiative

Fehrsa, K.; Wagenknecht, S.; Rades, J.; May, N.; Parvez, A. M.; Engesser, S.; Ferye, A.

Abstract

In recent decades, sustainability has emerged as a central theme in addressing future uncertainties, intertwined with discourses on ecology, conservation, resilience and socio-ecological justice. While much scholarly attention has focused on sustainability in industrial production, design, global development and lifestyles, the relationship between sustainability and basic research remains underexplored. This paper addresses this gap by examining how sustainability concerns are integrated into scientific practice, specifically within basic research in science and engineering. Through a collaborative ethnographic research process within an interdisciplinary initiative at the University of Technology Dresden, we explore how sustainability and basic research can inform one another. Our analysis draws on qualitative methods, including interviews and group discussions and is grounded in perspectives from sociology, anthropology and Science and Technology Studies (STS), particularly valuation studies. We investigate the various meanings of sustainability as invoked in the appraisal and evaluation of basic research, pursuing the question: What is valued when basic research is deemed ‘sustainable’? Our findings are organized around four central themes: sustainability as efficiency, sustainability through flexibility, sustainability assessment as estimation and sustainability assessment as finding leverage. These themes reveal the complexities and challenges of appraising basic research in terms of sustainability.

Keywords: Evaluation; Sustainability; Interdisciplinary; Basic Research

Permalink: https://www.hzdr.de/publications/Publ-39403


Aqueous extracts from Dioscorea sansibarensis Pax show cytotoxic and radiosensitizing potential in 3D growing HPV-negative and HPV-positive human head and neck squamous cell carcinoma models

Schott, M.; Vehlow, A.; Benka, M.; Lagies, S.; Kammerer, B.; Rieckmann, T.; Cordes, N.

Abstract

Numerous natural substances have anti-cancer properties. Especially indigenous people use aqueous plant extracts for tea or ointments including Dioscorea sansibarensis Pax to treat various diseases. The aim of this study was to evaluate the cytotoxic and radiosensitizing potential of aqueous extracts from Dioscorea sansibarensis Pax collected from Kenya in a panel of HPV-negative and -positive head and neck squamous cell carcinoma (HNSCC) cells grown in three-dimensional laminin-rich extracellular matrix (3D lrECM). The results show cytotoxicity, radiosensitization and increased levels of residual double strand breaks (DBS) by Dioscorea sansibarensis Pax extracts in HPV-negative and -positive HNSCC models in a concentration- and cell model-dependent manner. Application of ROS scavengers indicated an association between ROS-induced DSB and radiosensitization through Dioscorea sansibarensis Pax pretreatment. High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) based characterization of Dioscorea sansibarensis Pax identified the main components of the extract including camptothecin. Overall, Dioscorea sansibarensis Pax aqueous extracts alone and in combination with X-ray irradiation showed effective anticancer properties, which are worthy of further mechanistic investigation.

Keywords: Dioscorea sansibarensis Pax; HNSCC; radiosensitization; ionizing radiation; DNA repair; ROS

Permalink: https://www.hzdr.de/publications/Publ-39402


Combined PET radiotracer approach reveals insights into stro-mal cell-induced metabolic changes in pancreatic cancer in vitro and in vivo

Doctor, A.; Laube, M.; Meister, S.; Kiß, O.; Kopka, K.; Hauser, S.; Pietzsch, J.

Abstract

Pancreatic stellate cells (PSCs) in pancreatic adenocarcinoma (PDAC) are producing extracellular matrix, which promotes the formation of a dense fibrotic microenvironment. This makes PDAC a highly heterogeneous tumor-stroma driven entity, associated with reduced perfusion, limited oxygen supply, high interstitial fluid pressure, and limited bioavailability of therapeutic agents. In this study, spheroid and tumor xenograft co-culture models of human PSCs and PanC-1 cells were characterized radiopharmacologically using a combined positron emission tomography (PET) radiotracer approach. [18F]FDG, [18F]FMISO, and [18F]FAPI-74 were employed to monitor metabolic activity, hypoxic metabolic state, and functional expression of fibroblast activation protein alpha (FAPalpha), a marker of activated PSCs. In vitro, PanC-1 and co-culture spheroids demonstrated comparable glucose uptake and hypoxia, whereas FAPalpha expression was signifi-cantly higher in PSC spheroids. In vivo, glucose uptake as well as the transition to hypoxia was comparable in PanC-1 and co-culture xenograft models. In mice injected with PSCs FAPalpha ex-pression decreased over a period of four weeks post-injection, which was attributed to the suc-cessive death of PSCs. In contrast, FAPalpha expression increased in both PanC-1 and co-culture xenograft models over time due to invasion of mouse fibroblasts. The presented models are suitable for subsequently characterizing stromal cell-induced metabolic changes in tumors using noninvasive molecular imaging techniques.

Permalink: https://www.hzdr.de/publications/Publ-39401


Wake effect on bubble–particle collision: An experimental study using 4D particle tracking velocimetry

Sommer, A.-E.; Heitkam, S.; Eckert, K.

Abstract

The analysis of particle–bubble collisions in turbulent flow is a fundamental problem of high technological relevance, e.g., for the separation of valuable mineral particles by froth flotation. This relevance contrasts with an apparent lack of experimental data and understanding of this collision process. To this end, a periodic bubble chain was used to study the collision of millimeter-sized bubbles with polystyrene particles. The collision process between these entities was measured using 4D particle tracking velocimetry (PTV). By analyzing the collision data as a function of the polar angle along the bubble surface, we show that the collision took place not only at the leading edge but also at the trailing edge of the bubble. To understand the underlying mechanisms of the trailing edge collision, the flow field around a rising bubble chain was measured with Tomographic Particle Image Velocimetry (TPIV). The vortex formed in the bubble wake led to a velocity in the direction of the bubble surface that enabled trailing edge collisions. This effect is amplified by an increase in the turbulent kinetic energy and dissipation rate in the bubble wake. Overall, the investigation reveals different collision mechanisms and advances our understanding of the role of the wake in the bubble–particle collision.

Keywords: Bubble–particle collision; 4D particle tracking velocimetry; Tomographic particle image velocimetry; Froth flotation

Permalink: https://www.hzdr.de/publications/Publ-39399


A multi-sensor approach to measuring hydrodynamic parameters in a pyrite-quartz flotation system

Pervez, H.; Hassan, A.; Sommer, A.-E.; Zürner, T.; Pereira, L.; Rudolph, M.; Maaß, S.; Bowden, J.; Eckert, K.

Abstract

Improvement in resolving hydrodynamic variables in multiphase flows is key to optimizing flotation performance. However, due to equipment complexity and opacity of three-phase systems, in situ measurements become challenging. Therefore, by using a novel multi-sensor approach, the aim of this study is to spatially resolve key hydrodynamic and gas dispersion parameters in a mechanical flotation cell such as superficial gas velocity (Jg), gas holdup (εg), bubble size distribution (BSD), and bubble surface area flux (Sb). A high-resolution inline endoscope (SOPAT), Jg and εg sensors were fixed at multiple axial positions in a 6L nextSTEP™ flotation cell. This multi-sensor concept has been applied to a simplified benchmark flotation scenario, as part of a binary (pyrite-quartz) flotation test campaign (30 % solid load). Varying operating conditions include tip speed (4.7 – 5.5 m/s), air flow (0.4 – 0.5 cm/s), frother (MIBC: 30 – 60 g/ton), and collector concentrations (PAX: 30 – 60 g/ton). Sb is a good indicator of gas dispersion efficiency in flotation, and local measurements indicated that there are significant differences in the local superficial gas velocities which can be measured with our adapted sensor. Real-time bubble size measurements reflected the high shear rates near the rotor–stator region. Overall, the gas flow rate and frother concentration were shown to have the most significant effect on the gas dispersion in the benchmark flotation tests.

Keywords: Froth flotation; Hydrodynamics; Bubble size distribution

Permalink: https://www.hzdr.de/publications/Publ-39398


Human Performance in Predicting Enhancement Quality of Gliomas Using Gadolinium-Free MRI Sequences

Azizova, A.; Wamelink, I. J. H. G.; Prysiazhniuk, Y.; Cakmak, M.; Kaya, E.; Petr, J.; Barkhof, F.; Keil, V. C.

Abstract

Background and Purpose: To develop and test a decision tree for predicting contrast enhancement quality and shape using pre-contrast MRI sequences in a large adult-type diffuse glioma cohort.
Methods: Preoperative MRI scans (development/optimization/test sets: n=31/38/303, male=17/22/189, mean age=52/59/56.7 years, high-grade glioma=22/33/249) were retrospectively evaluated, including pre-and post-contrast T1-weighted, T2-weighted, fluid-attenuated inversion recovery, and diffusion-weighted imaging sequences. Enhancement prediction decision tree (EPDT) was developed using development and optimization sets, incorporating four imaging features: necrosis, diffusion restriction, T2 inhomogeneity, and nonenhancing tumor margins. EPDT accuracy was assessed on a test set by three raters of variable experience. True enhancement features (gold standard) were evaluated using pre- and post-contrast T1-weighted images. Statistical analysis used confusion matrices, Cohen’s/Fleiss’ kappa, and Kendall’s W. Significance threshold was P < 0.05.
Results: Raters 1, 2, and 3 achieved overall accuracies of 0.86 [95%-confidence interval (CI): 0.81-0.90], 0.89 (95%-CI: 0.85-0.92), and 0.92 (95%-CI: 0.89-0.95), respectively, in predicting enhancement quality (marked, mild, or no enhancement). Regarding shape, defined as the thickness of enhancing margin (solid, rim, or no enhancement), accuracies were 0.84 (95%-CI: 0.79-0.88), 0.88 (95%-CI: 0.84-0.92), and 0.89 (95%-CI: 0.85-0.92). Intra-rater inter-group agreement comparing predicted and true enhancement features consistently reached substantial levels [≥0.68 (95%-CI: 0.61-0.75). Inter-rater comparison showed at least moderate agreement (group: ≥0.42 (95%-CI: 0.36-0.48), pairwise: ≥0.61 (95%-CI: 0.50-0.72)]. Among the imaging features in the EPDT, necrosis assessment displayed the highest intra- and inter-rater consistency [≥0.80 (95%-CI: 0.73-0.88)].
Conclusion: The proposed enhancement prediction decision tree has high accuracy in predicting enhancement patterns of gliomas irrespective of rater experience.

Involved research facilities

  • PET-Center

Permalink: https://www.hzdr.de/publications/Publ-39397


Nuclear spin polarization in silicon carbide at room temperature in the Earth's magnetic field

Anisimov, A.; Poshakinskiy, A. V.; Astakhov, G.

Abstract

Experimental data and calculations.

Keywords: Quantum technology; Silicon carbide; Point defects; Optically detected magnetic resonance; Nuclear spin polarization

Downloads

Permalink: https://www.hzdr.de/publications/Publ-39396


Plant antagonistic facilitation across environmental gradients: a soil-resource ecosystem engineering model

Cabal, C.; Maciel, G. A.; Martinez Garcia, R.

Abstract

Theory questions the persistence of non-reciprocal interactions in which one plant has a positive net effect on a neighbor that, in return, has a negative net impact on its benefactor—a phenomenon known as antagonistic facilitation. We develop a spatially explicit consumer-resource model for below-ground plant competition between ecosystem engineers, plants able to mine resources and make them available for any other plant in the community, and exploiters. We use the model to determine in what environmental conditions antagonistic facilitation via soil resource engineering emerges as an optimal strategy. Antagonistic facilitation emerges in stressful environments where ecosystem engineers’ self-benefits from mining resources outweigh the competition with opportunistic neighbors. Among all potential causes of stress considered in the model, the key environmental parameter driving changes in the interaction between plants is the proportion of the resource that becomes readily available for plant consumption in the absence of any mining activity. Our results align with theories of primary succession and the stress gradient hypothesis. However, we find that the total root biomass and its spatial allocation through the root system, often used to measure the sign of the interaction between plants, do not predict facilitation reliably.

Keywords: Ecosystem engineers; Facilitation; Primary succession; Root competition; Stress gradient hypothesis; Soil amelioration

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Permalink: https://www.hzdr.de/publications/Publ-39395


Molecular and Crystal Structures of Pu(IV)-Nitrato Complexes with Double-Headed 2-Pyrrolidone Derivatives in HNO3(aq)

Ono, R.; Takeyama, T.; Gericke, R.; März, J.; Duckworth, T.; Tsushima, S.; Takao, K.

Abstract

Tetravalent actinides (An(IV)) widely occurs in the nuclear fuel cycle. For example, Pu(IV) and Th(IV) are the main species of these elements there, while U(IV) is also employed to reduce extractable Pu(IV) to unextractable Pu(III) in the PUREX process [1]. Therefore, the An(IV) chemistry needs to be understood in depth.
Previously, we have reported that An(IV) (An = Th, U, Np) commonly form sparingly soluble compounds with double-headed 2-pyrrolidone derivatives (L), (HL)2[An(NO3)6] (L = 14Cy and 12Cy, Fig. 1) in 3 M HNO3(aq) [2-3]. Based on these results, we have proposed an advanced principle for nuclear fuel reprocessing, namely NUuclear fuel MAterials selective Precipitation (NUMAP). In connection with this, we have preliminarily studied Ce(IV) as an inactive simulant of Pu(IV). However, Ce(IV) shows much different chemistry from that of An(IV), where [Ce2(μ-O)(NO3)6(14Cy)2]n including a [Ce-O-Ce]6+ motif is formed despite high acidic system with 3 M HNO3(aq) due to its strong hydrolysis tendency (Table 1) [4-5]. Up to now, Pu(IV) is known to exhibit both possibilities to form [Pu(NO3)6]2− and [Pu-O-Pu]6+ in crystal structures [6-7]. Therefore, we wonder which (HL)2[Pu(NO3)6] or [Pu2(μ-O)(NO3)6(L)2]n is preferred to be taken by Pu(IV) under presence of L in 3 M HNO3(aq). This makes critical difference in chemical stoichiometry of the Pu(IV) deposit for its recovery in the NUMAP reprocessing; the Pu:L mole ratio is 1:2 in (HL)2[Pu(NO3)6], while 1:1 in [Pu2(μ-O)(NO3)6(L)2]n. To answer this question, we have prepared Pu(IV)-nitrato complexes with L from HNO3(aq), and determined molecular and crystal structures of them as well as those of M(IV) analogues (M = Ce, Th, U).

  • Lecture (Conference)
    ATALANTE 2024, 01.-06.09.2024, Avignon, Frankreich

Permalink: https://www.hzdr.de/publications/Publ-39393


The 2024 magnonics roadmap

Flebus, B.; Grundler, D.; Rana, B.; Otani, Y.; Barsukov, I.; Barman, A.; Gubbiotti, G.; Landeros, P.; Akerman, J.; Ebels, U.; Pirro, P.; Demidov, V. E.; Schultheiß, K.; Csaba, G.; Wang, Q.; Ciubotaru, F.; Nikonov, D. E.; Che, P.; Hertel, R.; Ono, T.; Afanasiev, D.; Mentink, J.; Rasing, T.; Hillebrands, B.; Kusminskiy, S. V.; Zhang, W.; Du, C. R.; Finco, A.; van der Sar, T.; Luo, Y. K.; Shiota, Y.; Sklenar, J.; Yu, T.; Rao, J.

Abstract

Magnonics is a research field that has gained an increasing interest in both the fundamental and applied sciences in recent years. This field aims to explore and functionalize collective spin excitations in magnetically ordered materials for modern information technologies, sensing applications and advanced computational schemes. Spin waves, also known as magnons, carry spin angular momenta that allow for the transmission, storage and processing of information without moving charges. In integrated circuits, magnons enable on-chip data processing at ultrahigh frequencies without the Joule heating, which currently limits clock frequencies in conventional data processors to a few GHz. Recent developments in the field indicate that functional magnonic building blocks for in-memory computation, neural networks and Ising machines are within reach. At the same time, the miniaturization of magnonic circuits advances continuously as the synergy of materials science, electrical engineering and nanotechnology allows for novel on-chip excitation and detection schemes. Such circuits can already enable magnon wavelengths of 50 nm at microwave frequencies in a 5G frequency band. Research into non-charge-based technologies is urgently needed in view of the rapid growth of machine learning and artificial intelligence applications, which consume substantial energy when implemented on conventional data processing units. In its first part, the 2024 Magnonics Roadmap provides an update on the recent developments and achievements in the field of nano-magnonics while defining its future avenues and challenges. In its second part, the Roadmap addresses the rapidly growing research endeavors on hybrid structures and magnonics-enabled quantum engineering. We anticipate that these directions will continue to attract researchers to the field and, in addition to showcasing intriguing science, will enable unprecedented functionalities that enhance the efficiency of alternative information technologies and computational schemes.

Keywords: magnonics; road map; spin wave; microwave; neuromorphic; ferromagnet; antiferromagnet

Involved research facilities

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Permalink: https://www.hzdr.de/publications/Publ-39392


Highly efficient uranium uptake by the eco-designed cocamidopropyl betaine-decorated Na-P1 coal fly-ash zeolite

Sobczyk, M.; Roßberg, A.; Santhana Krishna Kumar, A.; Marzec, M.; Cwanek, A.; Łokas, E.; Nguyen Dinh, C.; Bajda, T.

Abstract

In some locations around the globe, the U concentrations may exceed WHO standards by 2-folds therefore, effective yet environmentally wise solutions to purify radioactive waters are of significant importance. Here, the optimized and fully controlled coal-fly-ash based Na-P1 zeolite functionalization by employing novel, biodegradable biosurfactant molecule - cocamidopropyl betaine (CAPB) is showcased. The zeolite’s surface decoration renders three composites with varying amounts of introduced CAPB molecule (Na-P1 @ CAPB), with 0.44, 0.88, and 1.59-times External Cation Exchange Capacity (ECEC). Wet-chemistry experiments revealed extremely high U adsorption capacity (qmax = 137.1 mg U/g) unveiling preferential interactions of uranyl dimers with CAPB molecules coupled with ion-exchange between Na+ ions. Multimodal spectroscopic analyses, including FourierTransformed Infra-Red (FT-IR), X-ray Photoelectron (XPS), and X-ray Absorption Fine Structure (XAFS), showed the hexavalent oxidation state of U, and no secondary release of the CAPB molecule from the composite. The EXAFS signals fingerprint changes in the interatomic distances of adsorbed U, showing the impact of the O and N, heteroatoms present in the CAPB molecule on U binding mechanism. The presented research outcomes showcase the easy, scalable, optimized, and environmentally friendly synthesis of biofunctional zeolite effectively purifying the real-life U-bearing wastewaters from the vicinity of the Pribram deposit (Czech Republic).

Keywords: Uranium Organo-minerals Biosurfactants XAS; Organo-minerals; Biosurfactants; XAS; Functional adsorbents

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Permalink: https://www.hzdr.de/publications/Publ-39391


Applying Circular Thermoeconomics for Sustainable Metal Recovery in PCB Recycling

Jorge, T.; César, T.; Alicia, V. D.; Antonio, V. C.; Parvez, A. M.; Sajjad, M.; Felipe, G. P.

Abstract

The impulse of the Fourth Industrial Revolution is triggering the demand for few specific metals. These include copper, silver, gold, and platinum group metals (PGMs), with important applications in renewable energies, green hydrogen, and electronic products. However, the continuous extraction of these metals is leading to a rapid decline in their ore grades and, consequently, increasing the environmental impact of extraction. Hence, obtaining metals from secondary sources, such as waste electrical and electronic equipment (WEEE), becomes imperative for both environmental sustainability and ensuring availability. This recovery entails few problems such as allocation due to the simultaneous production of several metals, the use of non-renewable resources, and the exergy destruction during the life cycle of the metals. Therefore, this work analyses the waste printed circuit boards (PCBs) recycling process by proposing different exergy-based cost allocations for the mentioned metals, disaggregating the exergy cost into non-renewable and renewable, and considering the complete life cycle of metals with the Circular Thermoeconomics methodology. The results show a significant saving of non-renewable energy by using renewable energies in primary extraction (67-87%), recycling (97.6-98.5%), and renewable energies in recycling (98.7%, 99.0%), compared to conventional primary extraction. However, when considering the entire life cycle, between 47% and 53% of the non-renewable exergy is destroyed during recycling. Therefore, delaying recycling as much as possible would be the most desirable option for maximizing the use of non-renewable resources, which nature cannot replace in a short time.

Keywords: Exergy Life Cycle; Thermoeconomics; Exergy Cost; Exergy Replacement Cost; Circular Economy; WEEE recycling

Permalink: https://www.hzdr.de/publications/Publ-39389


High precision stereotactic irradiation for focal drug-resistant epilepsy versus standard treatment: a randomized waitlist-controlled trial (the PRECISION-trial)

Zegers, C.; Swinnen, A.; Roumen, C.; Hofmann, A.; Troost, E. G. C.; van Asch, C.; Brandts, L.; Compter, I.; Dieleman, E.; Dijkstra, J.; Granzier, M.; Hendriks, M.; Hofman, P.; Houben, R.; Ramaekers, B.; Ronner, H.; Rouhl, R.; van der Salm, S.; Santegoeds, R.; Verhoeff, J.; Wagner, L.; Zwemmer, J.; Schijns, Q.; Colon, A.; Eekers, D.

Abstract

Introduction The standard treatment for patients with focal drug-resistant epilepsy (DRE) who are not eligible for
open brain surgery is the continuation of anti-seizure medication (ASM) and neuromodulation. This treatment does not cure epilepsy but only decreases severity. The PRECISION trial offers a non-invasive, possibly curative intervention for these patients, which consist of a single stereotactic radiotherapy (SRT) treatment. Previous studies have shown promising results of SRT in this patient population. Nevertheless, this intervention is not yet available and reimbursed in the Netherlands. We hypothesize that: SRT is a superior treatment option compared to palliative standard of care, for patients with focal DRE, not eligible for open surgery, resulting in a higher reduction of seizure frequency (with 50% of the patients reaching a 75% seizure frequency reduction at 2 years follow-up).
Methods In this waitlist-controlled phase 3 clinical trial, participants are randomly assigned in a 1:1 ratio to either
receive SRT as the intervention, while the standard treatments consist of ASM continuation and neuromodulation.
After 2-year follow-up, patients randomized for the standard treatment (waitlist-control group) are offered SRT.
Patients aged ≥ 18 years with focal DRE and a pretreatment defined epileptogenic zone (EZ) not eligible for open
surgery will be included. The intervention is a LINAC-based single fraction (24 Gy) SRT treatment. The target volume is defined as the epileptogenic zone (EZ) on all (non) invasive examinations. The seizure frequency will be monitored on a daily basis using an electronic diary and an automatic seizure detection system during the night. Potential side effects are evaluated using advanced MRI, cognitive evaluation, Common Toxicity Criteria, and patient-reported outcome questionnaires. In addition, the cost-effectiveness of the SRT treatment will be evaluated.
Discussion This is the first randomized trial comparing SRT with standard of care in patients with DRE, non-eligible for open surgery. The primary objective is to determine whether SRT significantly reduces the seizure frequency 2 years after treatment. The results of this trial can influence the current clinical practice and medical cost reimbursement in the Netherlands for patients with focal DRE who are not eligible for open surgery, providing a non-invasive curative treatment option.

Keywords: Epilepsy; Radiosurgery; Stereotactic radiation therapy (SRT); MRI; Cognition

Permalink: https://www.hzdr.de/publications/Publ-39388


Diffusion decrease in normal-appearing white matter structures following photon or proton irradiation indicates differences in regional radiosensitivity

Witzmann, K.; Raschke, F.; Wesemann, T.; Löck, S.; Funer, F.; Linn, J.; Troost, E. G. C.

Abstract

Purpose: Radio(chemo)therapy (RCT) as part of the standard treatment of glioma patients, inevitably leads to
radiation exposure of the tumor-surrounding normal-appearing (NA) tissues. The effect of radiotherapy on the
brain microstructure can be assessed by magnetic resonance imaging (MRI) using diffusion tensor imaging (DTI).
The aim of this study was to analyze regional DTI changes of white matter (WM) structures and to determine
their dose- and time-dependency.
Methods: As part of a longitudinal prospective clinical study (NCT02824731), MRI data of 23 glioma patients
treated with proton or photon beam therapy were acquired at three-monthly intervals until 36 months following
irradiation. Mean, radial and axial diffusivity (MD, RD, AD) as well as fractional anisotropy (FA) were investi-
gated in the NA tissue of 15 WM structures and their dependence on radiation dose, follow-up time and distance
to the clinical target volume (CTV) was analyzed in a multivariate linear regression model. Due to the small and
non-comparable patient numbers for proton and photon beam irradiation, a separate assessment of the findings
per treatment modality was not performed.
Results: Four WM structures (i.e., internal capsule, corona radiata, posterior thalamic radiation, and superior
longitudinal fasciculus) showed statistically significantly decreased RD and MD after RT, whereas AD decrease
and FA increase occurred less frequently. The posterior thalamic radiation showed the most pronounced changes
after RCT [i.e., ΔRD = −8.51 % (p = 0.012), ΔMD = −6.14 % (p = 0.012)]. The DTI changes depended
significantly on mean dose and time.
Conclusion: Significant changes in DTI for WM substructures were found even at low radiation doses. These
findings may prompt new radiation dose constraints sparing the vulnerable structures from damage and sub-
sequent side-effects.

Keywords: Magnetic resonance imaging; Diffusion-tensor imaging; Proton beam irradiation; Primary brain tumor; White matter structures

Permalink: https://www.hzdr.de/publications/Publ-39387


Radiomics for the detection of residual tumour status after surgery and patient outcome prediction after chemoradiotherapy in newly diagnosed glioblastoma based on [11C] methionine PET and T1c-w MRI

Shahzadi, I.; Seidlitz, A.; Beuthien-Baumann, B.; Zwanenburg, A.; Platzek, I.; Kotzerke, J.; Baumann, M.; Krause, M.; Troost, E. G. C.; Löck, S.

Abstract

Personalized treatment strategies based on non‑invasive biomarkers have potential to improve
patient management in patients with newly diagnosed glioblastoma (GBM). The residual tumour
burden after surgery in GBM patients is a prognostic imaging biomarker. However, in clinical patient
management, its assessment is a manual and time‑consuming process that is at risk of inter‑rater
variability. Furthermore, the prediction of patient outcome prior to radiotherapy may identify
patient subgroups that could benefit from escalated radiotherapy doses. Therefore, in this study,
we investigate the capabilities of traditional radiomics and 3D convolutional neural networks for
automatic detection of the residual tumour status and to prognosticate time‑to‑recurrence (TTR)
and overall survival (OS) in GBM using postoperative [11C] methionine positron emission tomography
(MET‑PET) and gadolinium‑enhanced T1‑w magnetic resonance imaging (MRI). On the independent
test data, the 3D‑DenseNet model based on MET‑PET achieved the best performance for residual
tumour detection, while the logistic regression model with conventional radiomics features performed
best for T1c‑w MRI (AUC: MET‑PET 0.95, T1c‑w MRI 0.78). For the prognosis of TTR and OS, the
3D‑DenseNet model based on MET‑PET integrated with age and MGMT status achieved the best
performance (Concordance‑Index: TTR 0.68, OS 0.65). In conclusion, we showed that both deep‑
learning and conventional radiomics have potential value for supporting image‑based assessment
and prognosis in GBM. After prospective validation, these models may be considered for treatment
personalization.

Permalink: https://www.hzdr.de/publications/Publ-39386


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