Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

"Online First" included
Approved and published publications
Only approved publications

41396 Publications

Efficient prediction of attosecond two-colour pulses from an X-ray free-electron laser with machine learning

Alaa El-Din, K. K.; Alexander, O. G.; Frasinski, L. J.; Mintert, F.; Guo, Z.; Duris, J.; Zhang, Z.; Cesar, D. B.; Franz, P.; Driver, T.; Walter, P.; Cryan, J. P.; Marinelli, A.; Marangos, J. P.; Mukherjee, R.

X-ray free-electron lasers are sources of coherent, high-intensity X-rays with numerous applications in ultra-fast measurements and dynamic structural imaging. Due to the stochastic nature of the self-amplified spontaneous emission process and the difficulty in controlling injection of electrons, output pulses exhibit significant noise and limited temporal coherence. Standard measurement techniques used for characterizing two-coloured X-ray pulses are challenging, as they are either invasive or diagnostically expensive. In this work, we employ machine learning methods such as neural networks and decision trees to predict the central photon energies of pairs of attosecond fundamental and second harmonic pulses using parameters that are easily recorded at the high-repetition rate of a single shot. Using real experimental data, we apply a detailed feature analysis on the input parameters while optimizing the training time of the machine learning methods. Our predictive models are able to make predictions of central photon energy for one of the pulses without measuring the other pulse, thereby leveraging the use of the spectrometer without having to extend its detection window. We anticipate applications in X-ray spectroscopy using XFELs, such as in time-resolved X-ray absorption and photoemission spectroscopy, where improved measurement of input spectra will lead to better experimental outcomes.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38437
Publ.-Id: 38437


Photon-photon correlation of condensed light in a microcavity

Tang, Y.; Shekhar Dhar, H.; Oulton, R. F.; Nyman, R. A.; Mintert, F.

The study of temporal coherence in a Bose-Einstein condensate of photons can be challenging, especially in the presence of correlations between the photonic modes. In this work, we use a microscopic, multimode model of photonic condensation inside a dye-filled microcavity and the quantum regression theorem, to derive an analytical expression for the equation of motion of the photon-photon correlation function. This allows us to derive the coherence time of the photonic modes and identify a nonmonotonic dependence of the temporal coherence of the condensed light with the cutoff frequency of the microcavity.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38435
Publ.-Id: 38435


First measurement of the 94Nb(n,γ) cross section at the CERN n_TOF facility

Balibrea-Correa, J.; Babiano-Suarez, V.; Lerendegui-Marco, J.; Junghans, A.; the n_TOF Collaboration

One of the crucial ingredients for the improvement of stellar models is the accurate knowledge of neutron capture cross-sections for the different isotopes involved in the s-,r- and i- processes. These measurements can shed light on existing discrepancies between observed and predicted isotopic abundances and help to constrain the physical conditions where these reactions take place along different stages of stellar evolution.

In the particular case of the radioactive 94Nb, the 94Nb(n,γ) cross-section could play a role in the determination of the s-process production of 94Mo in AGB stars, which presently cannot be reproduced by state-of-the-art stellar models. There are no previous 94Nb(n,γ) experimental data for the resolved and unresolved resonance regions mainly due to the difficulties in producing highquality samples and also due to limitations in conventional detection systems commonly used in time-of-flight experiments.

Motivated by this situation, a first measurement of the 94Nb(n,γ) reaction was carried out at CERN n_TOF, thereby exploiting the high luminosity of the EAR2 area in combination with a new detection system of small-volume C6D6-detectors and a high quality 94Nb-sample. The latter was based on hyper-pure 93Nb material activated at the high-flux reactor of ILL-Grenoble. An innovative ring-configuration detection system in close geometry around the capture sample allowed us to significantly enhance the signal-to-background ratio. This set-up was supplemented with two conventional C6D6-detectors and a highresolution LaCl3(Ce)-detector, which will be employed for addressing reliably systematic effects and uncertainties.

At the current status of the data analysis, 18 resonance in 94Nb+n have been observed for the first time in the neutron energy range from thermal up to 10 keV.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38434
Publ.-Id: 38434


The Training Catalogue for Photon and Neutron Data Services in DAPHNE

Knodel, O.; Pape, D.

Education is becoming an increasingly important topic to help scientists work on photon and neutron sources. Other relevant areas such as advanced quantum technologies will also play a key role in the future.

One of the goals of ExPaNDS (European Open Science Cloud (EOSC) Photon and Neutron Data Service) is to train research scientists in order to better understand the issues, methods and available computational RI infrastructures to address critical research questions.

Our training catalogue pan-training.eu, provids a one-stop shop for trainers and trainees to discover online information and content, including training materials, events and interactive tutorials. The catalogue provides opportunities to promote training events and news, and to contribute to a growing catalogue of materials; for trainers, the portal offers an environment for sharing materials and event information; for trainees, it offers a convenient gateway via which to identify relevant training events and resources, and to perform specific, guided analysis tasks via customised training workflows to provide FAIR research.

Keywords: Training catalogue; PaN Training; ExPaNDS; DAPHNE4NFDI

Permalink: https://www.hzdr.de/publications/Publ-38433
Publ.-Id: 38433


Breakdown of Temporal Coherence in Photon Condensates

Tang, Y.; Shekhar Dhar, H.; Oulton, R. F.; Nyman, R. A.; Mintert, F.

The temporal coherence of an ideal Bose gas increases as the system approaches the Bose-Einstein condensation threshold from below, with coherence time diverging at the critical point. However, counter-examples have been observed for condensates of photons formed in an externally pumped, dye-filled microcavity, wherein the coherence time decreases rapidly for increasing particle number above threshold. This paper establishes intermode correlations as the central explanation for the experimentally observed dramatic decrease in the coherence time beyond critical pump power.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38432
Publ.-Id: 38432


Finding Short Vectors in Structured Lattices with Reduced Quantum Resources

Eden, S.; Cong, L.; Mintert, F.

Leading protocols of post-quantum cryptosystems are based on the mathematical problem of finding short vectors in structured lattices. It is assumed that the structure of these lattices does not give an advantage for quantum and classical algorithms attempting to find short vectors. In this work we focus on cyclic and nega-cyclic lattices and give a quantum algorithmic framework of how to exploit the symmetries underlying these lattices. This framework leads to a significant saving in the quantum resources (e.g. qubits count and circuit depth) required for implementing a quantum algorithm attempting to find short vectors. We benchmark the proposed framework with the variational quantum eigensolver, and show that it leads to better results while reducing the qubits count and the circuit depth. The framework is also applicable to classical algorithms aimed at finding short vectors in structured lattices, and in this regard it could be seen as a quantum-inspired approach.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38430
Publ.-Id: 38430


High resolution 80Se(n,γ) cross section measurement at CERN n_TOF

Babiano-Suarez, V.; Balibrea-Correa, J.; Caballero-Ontanaya, L.; Junghans, A.

Neutron capture cross section measurements of isotopes close to s-process branching-points are of fundamental importance for the understanding of this nucleosynthesis mechanism through which about 50% of the elements heavier than iron are produced. We present in this contribution the results corresponding to the high resolution measurement, for first time ever, of the 80Se(n, γ) cross section, in which 98 resonances never measured before have been reported. As a consequence, ten times more precise values for the MACS have been obtained compared to previous accepted value adopted in the astrophysical KADoNiS data base.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38429
Publ.-Id: 38429


Bose-Einstein Condensation of Light in a Semiconductor Quantum Well Microcavity

Schofield, R. C.; Fu, M.; Clarke, E.; Farrer, I.; Trapalis, A.; Dhar, H. S.; Mukherjee, R.; Heffernan, J.; Mintert, F.; Nyman, R. A.; Oulton, R. F.

When particles with integer spin accumulate at low temperature and high density they undergo Bose-Einstein condensation (BEC). Atoms, solid-state excitons and excitons coupled to light all exhibit BEC, which results in high coherence due to massive occupation of the respective system's ground state. Surprisingly, photons were shown to exhibit BEC much more recently in organic dye-filled optical microcavities, which, owing to the photon's low mass, occurs at room temperature. Here we demonstrate that photons within an inorganic semiconductor microcavity also thermalise and undergo BEC. Although semiconductor lasers are understood to operate out of thermal equilibrium, we identify a region of good thermalisation in our system where we can clearly distinguish laser action from BEC. Based on well-developed technology, semiconductor microcavities are a robust system for exploring the physics and applications of quantum statistical photon condensates. Notably, photon BEC is an alternative to exciton-based BECs, which dissociate under high excitation and often require cryogenic operating conditions. In practical terms, photon BECs offer their critical behaviour at lower thresholds than lasers. Our study shows two further advantages of photon BEC in semiconductor materials: the lack of dark electronic states allows these BECs to be sustained continuously; and semiconductor quantum wells offer strong photon-photon scattering. We measure an unoptimised interaction parameter, g̃ =0.0023±0.0003, which is large enough to access the rich physics of interactions within BECs, such as superfluid light or vortex formation.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38428
Publ.-Id: 38428


Quantum simulations of time-dependent Hamiltonians beyond the quasi-static approximation

Shi, B.; Mintert, F.

Existing approaches to analogue quantum simulations of time-dependent quantum systems rely on perturbative corrections to the time-independence of the systems to be simulated. We overcome this restriction to perturbative approaches and demonstrate the potential of achievable quantum simulations with the pedagogical example of a Lambda-system and the quench in finite time through a quantum phase transition of a Chern insulator in a driven Hubbard system.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38427
Publ.-Id: 38427


Efficient estimation of quantum state k-designs with randomized measurements

Versini, L.; Alaa El-Din, K.; Mintert, F.; Mukherjee, R.

Random ensembles of pure states have proven to be extremely important in various aspects of quantum physics such as benchmarking the performance of quantum circuits, testing for quantum advantage, providing novel insights for many-body thermalization and studying black hole information paradox. Although generating a fully random ensemble is almost impossible and experimentally challenging, approximations of it are just as useful and are known to emerge naturally in a variety of physical models, including Rydberg setups. These are referred to as approximate quantum state designs, and verifying their degree of randomness can be an expensive task, similar to performing full quantum state tomography on many-body systems. In this theoretical work, we efficiently validate the character of approximate quantum designs with respect to data size acquisition when compared to conventional frequentist approach. This is achieved by translating the information residing in the complex many-body state into a succinct representation of classical data using a random projective measurement basis, which is then processed, using methods of statistical inference including neural networks. Our scheme of combining machine learning methods for postprocessing the data obtained from randomized measurements for efficient characterisation of (approximate) quantum state k designs is applicable to any noisy quantum platform that can generate quantum designs.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38426
Publ.-Id: 38426


Quantum simulation of hadronic states with Rydberg-dressed atoms

Wang, Z.; Wang, F.; Vovrosh, J.; Knolle, J.; Mintert, F.; Mukherjee, R.

The phenomenon of confinement is well known in high-energy physics and can also be realized for low-energy domain-wall excitations in one-dimensional quantum spin chains. A bound state consisting of two domain-walls can behave like a meson, and in a recent work of Vovrosh et al. [PRX Quantum 3, 040309 (2022)] , it was demonstrated that a pair of mesons could dynamically form a meta-stable confinement-induced bound state (consisting of four domain-walls) akin to a hadronic state. However, the protocol discussed in Vovrosh et al. [PRX Quantum 3, 040309 (2022)] involving the use of interactions with characteristically non-monotonic distance dependence is not easy to come by in nature, thus, posing a challenge for its experimental realization. In this regard, Rydberg atoms can provide the required platform for simulating confinement-related physics. We exploit the flexibility offered by interacting Rydberg-dressed atoms to engineering modified spin-spin interactions for the one-dimensional transverse field Ising model. Our numerical simulations show how Rydberg-dressed interactions can give rise to a variety of effective potentials that are suitable for hadron formation, which opens the possibility of simulating confinement physics with Rydberg platforms as a viable alternative to current trapped-ion experiments.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38425
Publ.-Id: 38425


Data publication - Danielle Maass and BioKollekt article 2024: Identification of yttrium oxide-specific peptides for future recycling of rare earth elements from electronic scrap

Maass, D.; Boelens, P.; Bloß, C.; Claus, G.; Harter, S. D.; Günther, D.; Pollmann, K.; Lederer, F.

Dieser Datensatz enthält die experimentell erworbenen und ausgewerteten Daten der Phagendisplayexperimente auf Y2O3.

Keywords: e-waste; mineral binding peptides; next-generation sequencing; phage surface display; waste of electrical and electronic equipment

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38423
Publ.-Id: 38423


Quantum algorithmic solutions to the shortest vector problem on simulated coherent Ising machines

Dable-Heath, E.; Casas, L.; Porter, C.; Mintert, F.; Ling, C.

Quantum computing poses a threat to contemporary cryptosystems, with advances to a state in which it will cause problems predicted for the next few decades. Many of the proposed cryptosystems designed to be quantum-secure are based on the Shortest Vector Problem and related problems. In this paper we use the Quadratic Unconstrained Binary Optimisation formulation of the Shortest Vector Problem implemented as a quantum Ising model on a simulated Coherent Ising Machine, showing progress towards solving SVP for three variants of the algorithm.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38422
Publ.-Id: 38422


Visualizing Chiral Interactions in Carbohydrates Adsorbed on Au(111) by High-Resolution STM Imaging

Seibel, J.; Fittolani, G.; Mir Hosseini, S. H.; Wu, X.; Rauschenbach, S.; Anggara, K.; Seeberger, P. H.; Delbianco, M.; Kühne, T. D.-S.; Schlickum, U.; Kern, K.

arbohydrates are the most abundant organic material on Earth and the structural “material of choice” in many living systems. Nevertheless, design and engineering of synthetic carbohydrate materials presently lag behind that for protein and nucleic acids. Bottom-up engineering of carbohydrate materials demands an atomic-level understanding of their molecular structures and interactions in condensed phases. Here, high-resolution scanning tunneling microscopy (STM) is used to visualize at submolecular resolution the three-dimensional structure of cellulose oligomers assembled on Au(1111) and the interactions that drive their assembly. The STM imaging, supported by ab initio calculations, reveals the orientation of all glycosidic bonds and pyranose rings in the oligomers, as well as details of intermolecular interactions between the oligomers. By comparing the assembly of D- and L-oligomers, these interactions are shown to be enantioselective, capable of driving spontaneous enantioseparation of cellulose chains from its unnatural enantiomer and promoting the formation of engineered carbohydrate assemblies in the condensed phases.

Keywords: Carbohydrate Materials; Chirality; Scanning Probe Microscopy; Self-Assembly; Electrospray Ionization

Permalink: https://www.hzdr.de/publications/Publ-38421
Publ.-Id: 38421


A segmented total energy detector (sTED) for (n, γ) cross section measurements at n_TOF EAR2

Alcayne, V.; Cano-Ott, D.; Garcia, J.; Junghans, A.; The n_TOF Collaboration

The neutron time-of-flight facility n_TOF is characterised by its high instantaneous neutron intensity, high-resolution and broad neutron energy spectra, specially conceived for neutron-induced reaction cross section measurements. Two Time-Of-Flight (TOF) experimental areas are available at the facility: experimental area 1 (EAR1), located at the end of the 185 m horizontal flight path from the spallation target, and experimental area 2 (EAR2), placed at 20 m from the target in the vertical direction. The neutron fluence in EAR2 is ˜ 300 times more intense than in EAR1 in the relevant time-of-flight window. EAR2 was designed to carry out challenging cross-section measurements with low mass samples (approximately 1 mg), reactions with small cross-sections or/and highly radioactive samples. The high instantaneous fluence of EAR2 results in high counting rates that challenge the existing capture systems. Therefore, the sTED detector has been designed to mitigate these effects. In 2021, a dedicated campaign was done validating the performance of the detector up to at least 300 keV neutron energy. After this campaign, the detector has been used to perform various capture cross section measurements at n_TOF EAR2.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38420
Publ.-Id: 38420


Kinetically Stable and Highly Ordered Two-Dimensional CN2 Crystal Structures

Nolkemper, K.; Antonietti, M.; Kühne, T. D.-S.; Ghasemi, S. A.

We present three dynamically and thermally stable polymorphs of CN2, which we identify through a systematic, multistep, and comprehensive structure search. They consist of nitrogen-rich structural motifs and modestly large pores. Kinetic stability is examined through long-term molecular dynamical simulations at an elevated temperature, where the interatomic interactions are treated using a new machine learning potential. Using density functional theory, we demonstrate their structural and electronic properties and compare them to polymorphs already available in the literature. The proposed structures are considerably more thermodynamically stable than their counterparts while desirably exhibiting energy levels suitable for photocatalytic water splitting. Also, calculations of enthalpy up to a modest value of external pressure show that the predicted polymorphs are thermodynamically more favorable than the previously proposed structures for high-pressure CN2.

Keywords: CN2; density functional theory; photocatalytic water splitting.

Permalink: https://www.hzdr.de/publications/Publ-38419
Publ.-Id: 38419


Breaking the exascale barrier for the electronic structure problem in ab-initio molecular dynamics

Schade, R.; Kenter, T.; Elgabarty, H.; Lass, M.; Kühne, T. D.-S.; Plessl, C.

The non-orthogonal local submatrix method applied to electronic structure–based molecular dynamics simulations is shown to exceed 1.1 EFLOP/s in FP16/FP32-mixed floating-point arithmetic when using 4400 NVIDIA A100 GPUs of the Perlmutter system. This is enabled by a modification of the original method that pushes the sustained fraction of the peak performance to about 80\%. Example calculations are performed for SARS-CoV-2 spike proteins with up to 83 million atoms.

Keywords: non-orthogonal local submatrix method; SARS-CoV-2

Permalink: https://www.hzdr.de/publications/Publ-38416
Publ.-Id: 38416


Extent of carbon nitride photocharging controls energetics of hydrogen transfer in photochemical cascade processes

Avateev, O.; Nolkemper, K.; Kühne, T. D.-S.; Shvalagin, V.; Markushyna, Y.; Antonietti, M.

Graphitic carbon nitride is widely studied in organic photoredox catalysis. Reductive quenching of carbon nitride excited state is postulated in many photocatalytic transformations. However, the reactivity of this species in the turn over step is less explored. In this work, we investigate electron and proton transfer from carbon nitride that is photocharged to a various extent, while the negative charge is compensated either by protons or ammonium cations. Strong stabilization of electrons by ammonium cations makes proton-coupled electron transfer uphill, and affords air-stable persistent carbon nitride radicals. In carbon nitrides, which are photocharged to a smaller extent, protons do not stabilize electrons, which results in spontaneous charge transfer to oxidants. Facile proton-coupled electron transfer is a key step in the photocatalytic oxidative-reductive cascade -- tetramerization of benzylic amines. The feasibility of proton-coupled electron transfer is modulated by adjusting the extent of carbon nitride photocharging, type of counterion and temperature.

Keywords: graphitic carbon nitride; proton-coupled electron transfe

Permalink: https://www.hzdr.de/publications/Publ-38414
Publ.-Id: 38414


MgO-S³: MgO-Spritzbeton für Streckenverschlüsse für HAW-Endlager im Steinsalz : Abschlussbericht zum FuE-Projekt

Gruner, M.; Kudla, W.; Arendt, J.; Freyer, D.; Kulenkampff, J.; Effner, U.; Lüdeling, C.; Müller, B.; Paschke, I.; Popp, T.; Wilsnack, T.

Bereits 2008 wurde im Rahmen des FuE-Projektes CARLA das Streckenverschlusselement GV2 aus MgO-Spritzbeton im Carnallititgebirge in der Grube Teutschenthal errichtet. Nach über acht Jahren Stand- und Reifezeit wurden im Rahmen des FuE-Projektes MgO-SEAL die Arbeiten am GV2 fortgesetzt. Hierbei wurde das chemische, geomechanische und geohydraulische Langzeitverhalten des Spritzbetondammes nach Lösungskontakt untersucht und bewertet. Die Ergebnisse werden für den (Langzeitsicherheits-) Nachweis der Integrität von Verschlussbauwerken aus MgO-Beton für zukünftige HAW-Endlager im Salinar benötigt.
In mehreren Bohrungen des GV2 wurden über 2,5 Jahre die Permeabilität mit MgCl₂-haltiger, NaCl-gesättigter Lösung regelmäßig gemessen. Die anfangs gemessene Lösungs-permeabilität (k_integral ≈ 2·10-15 m² bzw. k_integral ≈ 4·10-16 m²) verringerte sich um mehr als 4 Größenordnungen bis in den Bereich k_integral ≤ 10-19 m². Dieser Wert entspricht dem integralen Permeabilitätsniveau des kompakten MgO-Betons. Dies zeigte, dass sich MgO-Spritzbeton durch Phasenumwandlung selbst abdichten kann. Diese Porositätsverringerung bei Lösungszutritt wurde auch rechnerisch modellhaft beschrieben.
Für das aktuelle Projekt MgO-S³ wurde das Funktionsbauwerk GV2 teilweise zurückgebaut. Es wurde ein Teil seiner Mantelfläche freigelegt, um die Verteilung der Injektionsmittel zu begutachten. Die mit Lösung befüllten Bohrungen wurden überbohrt, um Veränderungen des Baustoffes nach Kontakt mit der Lösung feststellen zu können. Durch Permeabilitäts-messungen in den Bohrlöchern wurde gezeigt, dass bei Lösungszutritt in den Bereichen mit anfangs höherer Permeabilität sich die Permeabilität mit der Zeit < 10-18 m² verringert. Damit konnte der Selbstabdichtungseffekt des MgO-Spritzbetons bei Lösungszutritt bestätigt und verifiziert werden.
An drei Flächen wurden Ultraschalluntersuchungen durchgeführt, um mögliche Fehlstellen im Bauwerk zu detektieren.
In zahlreichen Spritzbetonversuchen im Technikumsmaßstab wurden verschiedene neue Rezepturvarianten erprobt. In situ in der Grube Teutschenthal wurde zunächst die Rezeptur des GV2 mit Spritzschichtmächtigkeiten von ca. 30 cm reproduziert und in zwei weiteren Versuchen wurde der Quarzzuschlag durch Salzzuschlag ersetzt. Diese hohen Schichtmächtigkeiten gehen mit hohen Abbindetemperaturen einher, die problematisch sein können. Um ein gutes Spritzen und einen hochwertigen Spritzbetonkörper zu gewährleisten, müssen die richtige Technik und die korrekten Einstellungen erprobt und gewählt werden.
An den Bohrkernen aus dem Spritzbeton wurden die Dichte, die Festigkeit, die Porosität, die Permeabilität gemessen sowie das zeitabhängige Verformungsverhalten untersucht. Außerdem wurde der Porenraum mittels CT und PET visualisiert. Die Spritzbetonkörper in situ wurden mit Ultraschall untersucht, um potenzielle Fehlstellen zu identifizieren.
Weiterhin wurde ein wissenschaftliches Programm für ein in situ Verschlussbauwerk aus MgO-Spritzbeton im Steinsalz erarbeitet. Dieses Programm beinhaltet die Versuchsziele und die Messgrößen für die Planung eines zukünftigen MgO-Spritzbetonstreckenverschlusses, einen Vorschlag für die begleitende Qualitätssicherung bzw. –dokumentation beim Bau eines MgO-Streckenverschlusses und einen Vorschlag bzw. Vorentwurf zum Aufbau eines MgO-Streckenverschlusses mit Instrumentierung.

Keywords: MgO-concrete; HAW final repository; salinar; tomography; PET; μCT; pore structure; permeability

  • Open Access Logo Other report
    Hannover: TIB, 2023
    384 Seiten

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38413
Publ.-Id: 38413


Measurement of the neutron-induced fission cross section of 230Th at the CERN n_TOF facility

Michalopoulou, V.; Stamatopoulos, A.; Diakaki, M.; Junghans, A.; n_TOF Collaboration

The neutron-induced fission cross section of 230 Th has been measured at the neutron time-of-flight facility
n_TOF located at CERN. The experiment was performed at the experimental area EAR-1 with a neutron flight
path of 185 m, using Micromegas detectors for the detection of the fission fragments. The 230 Th(n, f ) cross
section was determined relative to the 235 U(n, f ) one, covering the energy range from the fission threshold up to
400 MeV. The results from the present work are compared with existing cross-section datasets and the observed
discrepancies are discussed and analyzed. Finally, using the code EMPIRE 3.2.3 a theoretical study, based on the
statistical model, was performed leading to a satisfactory reproduction of the experimental results with the proper
tuning of the respective parameters, while for incident neutron energy beyond 200 MeV the fission of 230 Th was
described by Monte Carlo simulations.

Keywords: Fission; Nuclear Reactions; Nucleon induced nuclear reactions; A>220

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38412
Publ.-Id: 38412


Data publication: Mechanistic insight on water dissociation on pristine low-index TiO2 surfaces from machine learning molecular dynamics simulations

Zeng, Z.; Wodaczek, F.; Liu, K.; Stein, F.; Hutter, J.; Chen, J.; Cheng, B.

input files for the calculation of the training and verification data using CP2K, the input data for the machine learning potentials, input files for the metadynamics simulations using LAMMPS, an example analysis, data to create figures

Related publications

Permalink: https://www.hzdr.de/publications/Publ-38411
Publ.-Id: 38411


Causes and consequences of imperfect coordination in microbial collective behaviors

Martinez Garcia, R.; Rossine, F. W.; Sgro, A. E.; Gregor, T.; Tarnita, C. E.

Collective behaviors, in which many individuals exhibit some degree of behavioral coordination, are frequent across the tree of life and observed across a continuum of scales, from microbial aggregates to ungulate migrations. Intriguingly, however, such coordination is sometimes imperfect, and “out-of-sync” individuals have been reported in several of these systems. For example, in the model social amoeba Dictyostelium discoideum, free-living cells aggregate in a multicellular fruiting body upon starvation, while others remain in the unicellular phase. In several ungulate species, hundreds of thousands of individuals coordinate with each other to migrate across seasonal ranges, but resident populations that fail to migrate also exist. The roots of such imperfect coordination, and hence the mechanisms underlying the emergence of out-of-sync individuals, will undoubtedly differ across systems. Nevertheless, the occurrence of imperfect coordination across such different systems and scales raises fundamental questions about its causes and consequences. Are “out-of-sync” individuals merely inevitable byproducts of large-scale coordination attempts, or can they, at least in some systems, be a variable trait that selection can shape with potential ecological consequences?

  • Poster
    EMBO Workshop: Physics of living systems: From physical principles to biological function, 03.-07.07.2023, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-38410
Publ.-Id: 38410


Charge-exchange-dependent energy loss of H and He in freestanding monolayers of graphene and MoS2

Niggas, A.; Fischer, L.; Kretschmer, S.; Werl, M.; Biber, H.; Speckmann, C.; McEvoy, N.; Kotakoski, J.; Aumayr, F.; Krasheninnikov, A.; Wilhelm, R. A.

We study the energy loss of helium and hydrogen ions after transmission through monolayers of graphene and MoS2 and compare experimental results with different computational approaches. We find a systematically higher energy loss in experiments compared to simulations by up to a factor of 2. Additionally, our results show that neutralization processes of the particles increase the kinetic energy loss, a contribution generally not included in any computational approach.

Keywords: Atom or molecule scattering from surfaces; Electronic excitation & ionization; Interatomic & molecular potentials; 2-dimensional systems; Graphene; Ions; Surfaces; Transition metal dichalcogenides; Density functional theory; Ion beam analysis; Ion scattering from surfaces

Downloads

  • Secondary publication expected from 26.12.2024

Permalink: https://www.hzdr.de/publications/Publ-38408
Publ.-Id: 38408


Some considerations on the usage of compositional data in artificial intelligence

Tolosana Delgado, R.

Spatial dependence between samples is not the only particularity that data science, machine learning, deep learning or artificial intelligence should deal with in the geosciences: quite pervasive also is the existence of data with multivariate unconventional statistical scales. As an example, this contribution discusses the effects of the compositional metric on predictive algorithms, i.e., the way to compare compositional data, or data informing of the relative importance of some parts forming a whole.

Most machine learning methods (lasso or ridge regression, partition trees, random forests, artificial neural networks of any depth, support-vector machines (SVM) and other kernel methods, etc.) are mostly used to extract a response prediction rule out of a training data set with known responses. If compositional data play any role, either as explanatory or as response variable, there is a chance that its specific scale affects the performance of these methods.

The compositional scale is induced by the fact that the information conveyed by compositional data is only relative (of one part to another) and for the need to work with closed and non-closed sub-compositions (formed by a subset of the parts either summing to 100% or not). Dealing with these issues is particularly eased by taking an invertible set of (log)ratios of the parts, and several alternative logratio transformations have been proposed in the literature. However, for each of the methods above there is either an objectively preferred transformation, or else they provide all identical results. In this contribution we will review the properties of the compositional scale, of the transformations to logratio scores available, and how do they interact with the methods mentioned before.

  • Lecture (Conference)
    The 22nd annual conference of the IAMG, 05.-12.08.2023, Trondheim, Norwegen

Permalink: https://www.hzdr.de/publications/Publ-38407
Publ.-Id: 38407


Principal component analysis for distributional data with application to particle size distributions

Pavlu, I.; van den Boogaart, K. G.; Tolosana Delgado, R.; Machalova, J.; Hron, K.

Particle or grain size distributions often play an important role in understanding processes in the geosciences. Functional data analysis allows applying multivariate methods like principal components and discriminant analysis directly to such distributions. These are however often observed in the form of samples, and thus with a sampling error, i.e. each data point is a distribution, but one where the sampling error is present. This additional sampling error changes the properties of the multivariate variance and thus the value, number and direction of the principle components. The result of the principal component analysis becomes an artefact of the sampling error and can negatively affect the following data analysis.

Our contribution presents how to compute this sampling error and how to confront it in the context of principal component analysis. We demonstrate the effect of the sampling error and the effectiveness of the correction with a simulated dataset. We show how the interpretability and reproducibility of the principal components improve and become independent of the selection of the basis. We also demonstrate how the correction improves interpretability of the results on a grain size distribution dataset from river sediments.

Keywords: Compositional data analysis; Stratigraphy and Sedimentology

  • Lecture (Conference)
    The 22nd annual conference of the IAMG, 05.-12.08.2023, Trondheim, Norwegen

Permalink: https://www.hzdr.de/publications/Publ-38406
Publ.-Id: 38406


Geometallurgy: Present and Future

Frenzel, M.; Baumgartner, R.; Tolosana Delgado, R.; Gutzmer, J.

Geometallurgy is an interdisciplinary research field concerned with the planning, monitoring, and optimisation of mineral resource extraction and beneficiation. Geometallurgy relies on a quantitative understanding of primary resource characteristics such as mineralogical composition and texture, the spatial distribution and variability of these characteristics, and how they interact with mining and beneficiation processes. Thus, ­geometallurgy requires accurate analytical data for resource characterisation and detailed models of orebody geology, mining and processing technologies, mineral economics, and the often-complex interactions between them. Here, we introduce the fundamental concepts relevant to the field, with particular emphasis on the current state-of-the-art and some notes on potential future developments

Keywords: raw materials; sustainability; value chains; resource efficiency

Permalink: https://www.hzdr.de/publications/Publ-38405
Publ.-Id: 38405


Sulfide-Bridged Covalent Quinoxaline Frameworks for Lithium–Organosulfide Batteries

Haldar, S.; Bhauriyal, P.; Ramuglia, A. R.; Khan, A. H.; de Kock, S.; Hazra, A.; Bon, V.; Pastoetter, D. L.; Kirchhoff, S.; Shupletsov, L.; De, A.; Isaacs, M. A.; Feng, X.; Walter, M.; Brunner, E.; Weidinger, I. M.; Heine, T.; Schneemann, A.; Kaskel, S.

The chelating ability of quinoxaline cores and the redox activity of organosulfide bridges in layered covalent organic frameworks (COFs) offer dual active sites for reversible lithium (Li)-storage. The designed COFs combining these properties feature disulfide and polysulfide-bridged networks showcasing an intriguing Li-storage mechanism, which can be considered as a lithium–organosulfide (Li–OrS) battery. The experimental–computational elucidation of three quinoxaline COFs containing systematically enhanced sulfur atoms in sulfide bridging demonstrates fast kinetics during Li interactions with the quinoxaline core. Meanwhile, bilateral covalent bonding of sulfide bridges to the quinoxaline core enables a redox-mediated reversible cleavage of the sulfursulfur bond and the formation of covalently anchored lithium–sulfide chains or clusters during Li-interactions, accompanied by a marked reduction of Li–polysulfide (Li–PS) dissolution into the electrolyte, a frequent drawback of lithium–sulfur (Li–S) batteries. The electrochemical behavior of model compounds mimicking the sulfide linkages of the COFs and operando Raman studies on the framework structure unravels the reversibility of the profound Li-ion–organosulfide interactions. Thus, integrating redox-active organic-framework materials with covalently anchored sulfides enables a stable Li–OrS battery mechanism which shows benefits over a typical Li–S battery.

Keywords: covalent organic frameworks; lithium–organosulfide batteries

Permalink: https://www.hzdr.de/publications/Publ-38402
Publ.-Id: 38402


2D Few-Layered PdPS: Toward High-Efficient Self-Powered Broadband Photodetector and Sensor

Roy, P. K.; Antonatos, N.; Li, T.; Jing, Y.; Luxa, J.; Azadmanjiri, J.; Marvan, P.; Heine, T.; Sofer, Z.

Photodetectors and sensors have a prominent role in our lives and cover a wide range of applications, including intelligent systems and the detection of harmful and toxic elements. Although there have been several studies in this direction, their practical applications have been hindered by slow response and low responsiveness. To overcome these problems, we have presented here a self-powered (photoelectrochemical, PEC), ultrasensitive, and ultrafast photodetector platform. For this purpose, a novel few-layered palladium–phosphorus–sulfur (PdPS) was fabricated by shear exfoliation for effective photodetection as a practical assessment. The characterization of this self-powered broadband photodetector demonstrated superior responsivity and specific detectivity in the order of 33 mA W–1 and 9.87 × 1010 cm Hz1/2 W–1, respectively. The PEC photodetector also exhibits a broadband photodetection capability ranging from UV to IR spectrum, with the ultrafast response (∼40 ms) and recovery time (∼50 ms). In addition, the novel few-layered PdPS showed superior sensing ability to organic vapors with ultrafast response and a recovery time of less than 1 s. Finally, the photocatalytic activity in the form of hydrogen evolution reaction was explored due to the suitable band alignment and pronounced light absorption capability. The self-powered sensing platforms and superior catalytic activity will pave the way for practical applications in efficient future devices.

Keywords: Photodetectors; PdPS; Two dimensional materials

Permalink: https://www.hzdr.de/publications/Publ-38399
Publ.-Id: 38399


Vibrational spectroscopy of Cu+(H2)4: about anharmonicity and fluxionality

Jin, J.; Wulf, T.; Jorewitz, M.; Heine, T.; Asmis, K. R.

The vibrational spectra of the copper(i) cation–dihydrogen complexes Cu+(H2)4{,} Cu+(D2)4 and Cu+(D2)3H2 are studied using cryogenic ion trap vibrational spectroscopy in combination with quantum chemical calculations. The infrared photodissociation (IRPD) spectra (2500–7300 cm−1) are assigned based on a comparison to IR spectra calculated using vibrational second-order perturbation theory (VPT2). The IRPD spectra exhibit ≈60 cm−1 broad bands that lack rotational resolution{,} indicative of rather floppy complexes even at an ion trap temperature of 10 K. The observed vibrational features are assigned to the excitations of dihydrogen stretching fundamentals{,} combination bands of these fundamentals with low energy excitations as well as overtone excitations of a minimum-energy structure with Cs symmetry. The three distinct dihydrogen positions present in the structure can interconvert via pseudorotations with energy barriers less than 10 cm−1{,} far below the zero-point vibrational energy. Ab initio Born–Oppenheimer molecular dynamics (BOMD) simulations confirm the fluxional behavior of these complexes and yield an upper limit for the timeframe of the pseudorotation on the order of 10 ps. For Cu+(D2)3H2{,} the H2 and D2 loss channels yield different IRPD spectra indicating non-ergodic behavior.

Keywords: vibrational spectra; cryogenic ion trap vibrational spectroscopy; vibrational second-order perturbation theory

Permalink: https://www.hzdr.de/publications/Publ-38398
Publ.-Id: 38398


Oscillatory large-scale circulation in liquid-metal thermal convection and its structural unit

Teimurazov, A.; Singh, S.; Su, S.; Eckert, S.; Shishkina, O.; Vogt, T.

In Rayleigh–Bénard convection, the size of a flow domain and its aspect ratio Γ (a ratio
between the spatial length and height of the domain) affect the shape of the large-scale
circulation. For some aspect ratios, the flow dynamics includes a three-dimensional
oscillatory mode known as a jump rope vortex (JRV); however, the effects of varying
aspect ratios on this mode are not well investigated. In this paper, we study these aspect
ratio effects in liquid metals, for a low Prandtl number Pr = 0.03. Direct numerical
simulations and experiments are carried out for a Rayleigh number range 2.9 × 104 ≤
Ra ≤ 1.6 × 106 and square cuboid domains with Γ = 2, 2.5, 3 and 5. Our study
demonstrates that a repeating pattern of a JRV encountered at aspect ratio Γ ≈ 2.5 is the
basic structural unit that builds up to a lattice of interlaced JRVs at the largest aspect ratio.
The size of the domain determines how many structural units are self-organised within
the domain; the number of the realised units is expected to scale as Γ 2 with sufficiently
large and growing Γ . We find the oscillatory modes for all investigated Γ ; however, they
are more pronounced for Γ = 2.5 and 5. Future studies for large-aspect-ratio domains of
different shapes would enhance our understanding of how the JRVs adjust and reorganise
at such scaled-up geometries, and answer the question of whether they are indeed the
smallest superstructure units.

Keywords: Rayleigh–Bénard convection; turbulent convection

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38396
Publ.-Id: 38396


Understanding MOF Flexibility: An Analysis Focused on Pillared Layer MOFs as a Model System}

Senkovska, I.; Bon, V.; Abylgazina, L.; Mendt, M.; Berger, J.; Kieslich, G.; Petkov, P.; Luiz, J.; Joswig, J.-O.; Heine, T.; Schaper, L.; Bachetzky, C.; Schmid, R.; Fischer, R. A.; Pöppl, A.; Brunner, E.; Kaskel, S.

Flexible porous frameworks are at the forefront of materials research. A unique feature is their ability to open and close their pores in an adaptive manner induced by chemical and physical stimuli. Such enzyme-like selective recognition offers a wide range of functions ranging from gas storage and separation to sensing, actuation, mechanical energy storage and catalysis. However, the factors affecting switchability are poorly understood. In particular, the role of building blocks, as well as secondary factors (crystal size, defects, cooperativity) and the role of host–guest interactions, profit from systematic investigations of an idealized model by advanced analytical techniques and simulations. The review describes an integrated approach targeting the deliberate design of pillared layer metal–organic frameworks as idealized model materials for the analysis of critical factors affecting framework dynamics and summarizes the resulting progress in their understanding and application.

Keywords: Flexibility Control; Paddle Wheel; Pillared Layer MOFs; Switchability

Permalink: https://www.hzdr.de/publications/Publ-38395
Publ.-Id: 38395


A thienyl-benzodithiophene-based two-dimensional conjugated covalent organic framework for fast photothermal conversion

Liu, Y.; Wang, M.; Dong, C.; Yu, H.; Lu, Y.; Huang, X.; Paasch, S.; Brunner, E.; Heine, T.; Song, F.; Auras, F.; Xu, F.; Mai, Y.; Feng, X.

wo-dimensional conjugated covalent organic frameworks (2D c-COFs) are emerging semiconductor materials for optoelectronic and photothermal applications. In particular, the highly tailorable, semiconducting thiophene-based 2D c-COFs have attracted considerable interest due to their nontrivial physicochemical properties such as photo-activity, broad optical absorption, tunable electronic structures, and so forth. Herein, we demonstrate a novel, crystalline 2D c-COF based on thienyl-functionalized benzodithiophene (BDT) and biphenyl (BP) via the Schiff-base polycondensation reaction. The resultant BDT-BP-COF exhibits a broad optical absorption up to ca. 600 nm and decent π-conjugation along the 2D polymer skeleton, as revealed by the optical absorption and theoretical calculations. The favorable π-conjugation and the abundant electron-rich thiophene units confer excellent photo-activity to BDT-BP-COF towards the usage of solar energy. As a proof-of-concept application, we explore BDT-BP-COF in photothermal conversion, in which it shows a fast surface-temperature increase upon light irradiation for seconds.

Keywords: photothermal conversion; thienyl-benzodithiophene; two-dimensional conjugated covalent organic framework; π-conjugation

Permalink: https://www.hzdr.de/publications/Publ-38394
Publ.-Id: 38394


Geometallurgy workshop @ Sandfire

Tolosana Delgado, R.; Pereira, L.

The field of geometallurgy has largely contributed to the efficiency of the raw materials sector. In this workshop, we covered the main building blocks of a geometallurgy program: geostatistics, mineral characterization, uncertainties, mineral processing, and particle-based modelling.

Keywords: Froth flotation; Particle based modelling; Geometallurgy; Geostatistics; Uncertainties

  • Lecture (others)
    Geometallurgy workshop @ Sandfire Matsa, 04.-05.10.2023, Huelva, Spain

Permalink: https://www.hzdr.de/publications/Publ-38393
Publ.-Id: 38393


Predicting Magnetic Coupling and Spin-Polarization Energy in Triangulene Analogues

Yu, H.; Sun, J.; Heine, T.

Triangulene and its analogue metal-free magnetic systems have garnered increasing attention since their discovery. Predicting the magnetic coupling and spin-polarization energy with quantitative accuracy is beyond the predictive power of today’s density functional theory (DFT) due to their intrinsic multireference character. Herein, we create a benchmark dataset of 25 magnetic systems with nonlocal spin densities, including the triangulene monomer, dimer, and their analogues. We calculate the magnetic coupling (J) and spin-polarization energy (ΔEspin) of these systems using complete active space self-consistent field (CASSCF) and coupled-cluster methods as high-quality reference values. This reference data is then used to benchmark 22 DFT functionals commonly used in material science. Our results show that, while some functionals consistently correctly predict the qualitative character of the ground state, achieving quantitative accuracy with small relative errors is currently not feasible. PBE0, M06-2X, and MN15 are predicting the correct electronic ground state for all systems investigated here and also have the lowest mean absolute error for predicting both ΔEspin (0.34, 0.32, and 0.31 eV) and J (11.74, 12.66, and 10.64 meV). They may therefore also serve as starting points for higher-level methods such as the GW or the random phase approximation. As other functionals fail for the prediction of the ground state, they cannot be recommended for metal-free magnetic systems.

Keywords: Electron correlation; Monomers; Oligomers

Permalink: https://www.hzdr.de/publications/Publ-38392
Publ.-Id: 38392


Geometallurgy workshop @ Nexa

Pereira, L.

The field of automated mineralogy has largely contributed to our understanding of mineral processing. Lately, by evaluating the particle information collected with automated mineralogy using statistical learning methods, it became possible to quantify the process behaviour of individual particles with consideration to their size, shape, liberation, and mineral association. In this workshop, we explore the latest methods used to quantify the recoverability of individual particles and how their results can be used to better understand mineral processing.

Keywords: Froth flotation; Particle based modelling; Geometallurgy; Raw materials

  • Invited lecture (Conferences)
    Geometallurgy workshop @ Nexa, 23.11.2023, Vazante, Brazil

Permalink: https://www.hzdr.de/publications/Publ-38391
Publ.-Id: 38391


Epitaxial Stabilization of Perovskite ATeO3 Thin Films

Herklotz, A.; Stefania Rus, F.; Koch, M. M.; Grove, K. M.; Bowen, M. S.; Cann, D. P.; Tippey, K. E.; Dörr, K.

Tellurium oxides of the ATeO3 form typically do not crystallize in perovskite structures.
Here, we show that perovskite-like ATeO3 (A = Ca, Sr, Ba) thin films can be grown on perovskite
single-crystal substrates via epitaxial stabilization. These films are stable with high optical bandgaps,
low dielectric losses, and a high electric breakdown strength. Hysteretic dielectric behavior found
in SrTeO3 and BaTeO3 strongly suggests the presence of antiferroelectricity and ferroelectricity,
respectively. These properties make perovskite tellurium oxides possibly appealing candidates for
thin film coating or insulator materials in advanced microelectronics. Tellurium oxides constitute a
largely unexplored class of materials that might show new and interesting functionalities in epitaxial
thin-films. Our work encourages new work within this field.

Keywords: perovskite; ferroelectric; chalcogenide

Permalink: https://www.hzdr.de/publications/Publ-38389
Publ.-Id: 38389


Solution-Processed Formation of DNA-Origami-Supported Polyoxometalate Multi-Level Switches with Countercation-Controlled Conductance Tunability

Vogelsberg, E.; Moors, M.; Sorokina, A. S.; Ryndyk, D. A.; Schmitz, S.; Freitag, J. S.; Subbotina, A. V.; Heine, T.; Abel, B.; Monakhov, K. Y.

We report a chemically programmed design and the switching characteristics of a functional metal–DNA-origami–polyoxometalate (POM) material obtained from the solution-processed assembling of biocompatible molecular precursors. The DNA origami is immobilized on the gold surface via thiolate groups and acts as a carrier (ad-layer) structure, ensuring the spatially controlled hybridization of the pre-defined six-helix bundle (6HB) positions with DNA-augmented, tris(alkoxo)-ligated Lindqvist-type polyoxovanadate (POV6) units. The DNA-confined POV6 units accept electrons in a stepwise fashion, allowing for a multi-logic function, which we directly probe using scanning tunneling electron microscopy and spectroscopy. Electron acceptance and injection into the originally non-conducting DNA structure and the subsequent release to the gold substrate depend upon the potential at the nanoscale tip and the oxidation state of POV6, as well as on the mechanism of action of POV6 countercations. By combining experiment and theory, we show that the bio-hybrid heterojunction has far-reaching potential to create a chemically controlled POM-based nano-environment with synaptic behavior.

Keywords: DNA-origami; Solution chemistry

Permalink: https://www.hzdr.de/publications/Publ-38388
Publ.-Id: 38388


Hybrid star phenomenology from the properties of the special point

Gärtlein, C.; Ivanytskyi, O.; Sagun, V.; Blaschke, D.

We study the properties of hybrid stars containing a color superconducting quark matter phase in their
cores, which is described by the chirally symmetric formulation of the confining relativistic density
functional approach. It is shown that, depending on the dimensionless vector and diquark couplings of
quark matter, the characteristics of the deconfinement phase transition are varied, allowing us to study the
relation between those characteristics and mass-radius relations of hybrid stars. Moreover, we show that the
quark matter equation of state (EoS) can be nicely fitted by the Alford-Braby-Paris-Reddy model that gives
a simple functional dependence between the most important parameters of the EoS and microscopic
parameters of the initial Lagrangian. Based on it, we analyze the special points of the mass-radius diagram
in which several mass-radius curves intersect. Using the found empirical relation between the mass of the
special point, the maximum mass of the mass-radius curve, and the onset mass of quark deconfinement,
we constrain the range of values of the vector and diquark couplings of the quark matter model. With this
constraint, we construct a family of mass-radius curves, which allow us to describe the black widow pulsar
PSR J0952-0607 with a mass of 2.35 +/- 0.17M⊙ as a hybrid star with a color superconducting quark
matter core.

Keywords: Quark matter in neutron stars; Quark-gluon plasma; Dense nuclear matter; High-mass pulsars; PSR J0952-0607; PSR J0740+6620; PSR J0030+0451; GW170817

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38387
Publ.-Id: 38387


Magnetic Coupling Control in Triangulene Dimers

Yu, H.; Heine, T.

Metal-free magnetism remains an enigmatic field, offering prospects for unconventional magnetic and electronic devices. In the pursuit of such magnetism, triangulenes, endowed with inherent spin polarization, are promising candidates to serve as monomers to construct extended structures. However, controlling and enhancing the magnetic interactions between the monomers persist as a significant challenge in molecular spintronics, as so far only weak antiferromagnetic coupling through the linkage has been realized, hindering their room temperature utilization. Herein, we investigate 24 triangulene dimers using first-principles calculations and demonstrate their tunable magnetic coupling (J), achieving unprecedented strong J values of up to −144 meV in a non-Kekulé dimer. We further establish a positive correlation between bandgap, electronic coupling, and antiferromagnetic interaction, thereby providing molecular-level insights into enhancing magnetic interactions. By twisting the molecular fragments, we demonstrate an effective and feasible approach to control both the sign and strength of J by tuning the balance between potential and kinetic exchanges. We discover that J can be substantially boosted at planar configurations up to −198 meV. We realize ferromagnetic coupling in nitrogen-doped triangulene dimers at both planar and largely twisted configurations, representing the first example of ferromagnetic triangulene dimers that cannot be predicted by the Ovchinnikov rule. This work thus provides a practical strategy for augmenting magnetic coupling and open up new avenues for metal-free ferromagnetism.

Keywords: Group theory; Magnetic properties; Metal-free magnetism

Permalink: https://www.hzdr.de/publications/Publ-38386
Publ.-Id: 38386


Thiol-based defect healing of WSe2 and WS2

Schwarz, A.; Alon-Yehezkel, H.; Levi, A.; Yadav, R. K.; Majhi, K.; Tzuriel, Y.; Hoang, L.; Bailey, C. S.; Brumme, T.; Mannix, A. J.; Cohen, H.; Yalon, E.; Heine, T.; Pop, E.; Cheshnovsky, O.; Naveh, D.

Recent research on two-dimensional (2D) transition metal dichalcogenides (TMDCs) has led to remarkable discoveries of fundamental phenomena and to device applications with technological potential. Large-scale TMDCs grown by chemical vapor deposition (CVD) are now available at continuously improving quality, but native defects and natural degradation in these materials still present significant challenges. Spectral hysteresis in gate-biased photoluminescence (PL) measurements of WSe2 further revealed long-term trapping issues of charge carriers in intrinsic defect states. To address these issues, we apply here a two-step treatment with organic molecules, demonstrating the ``healing'' of native defects in CVD-grown WSe2 and WS2 by substituting atomic sulfur into chalcogen vacancies. We uncover that the adsorption of thiols provides only partial defect passivation, even for high adsorption quality, and that thiol adsorption is fundamentally limited in eliminating charge traps. However, as soon as the molecular backbone is trimmed and atomic sulfur is released to the crystal, both bonds of the sulfur are recruited to passivate the divalent defect and the semiconductor quality improves drastically. Time-dependent X-ray photoelectron spectroscopy (XPS) is applied here together with other methods for the characterization of defects, their healing, leading energies and occupation. First-principles calculations support a unified picture of the electronic passivation of sulfur-healed WSe2 and WS2. This work provides a simple and efficient method for improving the quality of 2D semiconductors and has the potential to impact device performance even after natural degradation.

Keywords: Two-dimensional transition metal dichalcogenides; WSe2; WS2; chemical vapor deposition

Permalink: https://www.hzdr.de/publications/Publ-38385
Publ.-Id: 38385


Nomadic ungulate movements under threat: Declining mobility of Mongolian gazelles in the Eastern Steppe of Mongolia

Mendgen, P.; Dejid, N.; Olson, K.; Buuveibaatar, B.; Calabrese, J.; Chimeddorj, B.; Dalannast, M.; Fagan, W.; Leimgruber, P.; Müller, T.

Increasing habitat fragmentation and disturbance threaten long-distance movements of ungulates. While the effects of impermeable barriers on ungulate migrations have been well researched, quantitative evidence for gradual, long-term changes of mobility remains rare.

We investigated changes in movement behavior of Mongolian gazelle Procapra gutturosa using GPS tracking data collected from 62 gazelle individuals between 2007 and 2021. We quantified 16-day displacement distances as a metric for long-distance movements before using linear mixed models, generalized additive models and quantile regressions to assess how anthropogenic and environmental factors affected gazelle movement behavior.

Long-distance 16-day movements decreased by 36 %, from 142 km in 2007 to 92 km in 2021. Changes in mobility were affected by increasing vehicle numbers in Mongolia, but could not be explained by concurrent changes in other environmental factors like temperature, precipitation or vegetation greenness. Gazelle movement decreased close to roads, and gazelles stayed further away from roads during the snow-free season, when traffic likely is most intense.

Conserving landscape permeability is essential for maintaining populations of highly mobile species. Our study provides evidence for a gradual decline in gazelle mobility over fifteen years as a response to increasing anthropogenic impact. The transportation infrastructure permeating the Eastern Steppe does not pose physical barriers, yet our findings suggest that increasing traffic volume may create semipermeable barriers to gazelle movement. As human activity is increasing, interactions between ungulates and vehicle traffic need to be closely monitored to identify and mitigate semipermeable barrier effects before landscape permeability is severely altered.

Keywords: Animal movement; Connectivity; GPS tracking; Semipermeable barriers; Traffic; Ungulate migration

Permalink: https://www.hzdr.de/publications/Publ-38381
Publ.-Id: 38381


FIB-tailored quantum-matter experiments

Helm, T.

es hat kein aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences)
    HZDR Science Conference 2023, 15.-15:11:2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38379
Publ.-Id: 38379


Covalent Trapping of Cyclic-Polysulfides in Perfluorinated Vinylene-Linked Frameworks for Designing Lithium-Organosulfide Batteries

Haldar, S.; Waentig, A. L.; Ramuglia, A. R.; Bhauriyal, P.; Khan, A. H.; Pastoetter, D. L.; Isaacs, M. A.; De, A.; Brunner, E.; Wang, M.; Heine, T.; Weidinger, I. M.; Feng, X.; Schneemann, A.; Kaskel, S.

The strategic combination of redox-active triazine- or quinoxaline-based lithium-ion battery (LIB) mechanisms with the polysulfide ring-mediated lithium-sulfur battery (Li-SB) mechanism enabled the configuration of covalent organic-framework (COF)-derived lithium-organosulfide (Li-OrSB) battery systems. Two vinylene-linked frameworks were designed by enclosing polysulfide rings via postsynthetic framework sulfurization, allowing for the separate construction of triazine-polysulfide and quinoxaline-polysulfide redox couples that can readily interact with Li ions. The inverse vulcanization of the vinylene linking followed by the sulfurization-induced nucleophilic aromatic substitution reaction (SNAr) on the perfluorinated aromatic center of the COFs enabled the covalent trapping of cyclic-polysulfides. The experimentally observed reversible Li-interaction mechanism of these highly conjugated frameworks was computationally verified and supported by in situ Raman studies, demonstrating a significant reduction of polysulfide shuttle in a conventional Li-SB and opening the door for a COF-derived high-performing Li-OrSB.

Keywords: Batteries; Covalent organic frameworks; Electrolytes; Redox reactions; Lithiation

Permalink: https://www.hzdr.de/publications/Publ-38378
Publ.-Id: 38378


Rational Molecular Design of Redox-Active Carbonyl-Bridged Heterotriangulenes for High-Performance Lithium-Ion Batteries

Shu, X.; Hu, L.; Heine, T.; Jing, Y.

Abstract Carbonyl aromatic compounds are promising cathode candidates for lithium-ion batteries (LIBs) because of their low weight and absence of cobalt and other metals, but they face constraints of limited redox-potential and low stability compared to traditional inorganic cathode materials. Herein, by means of first-principles calculations, a significant improvement of the electrochemical performance for carbonyl-bridged heterotriangulenes (CBHTs) is reported by introducing pyridinic N in their skeletons. Different center atoms (B, N, and P) and different types of functionalization with nitrogen effectively regulate the redox activity, conductivity, and solubility of CBHTs by influencing their electron affinity, energy levels of frontier orbitals and molecular polarity. By incorporating pyridinic N adjacent to the carbonyl groups, the electrochemical performance of N-functionalized CBHTs is significantly improved. Foremost, the estimated energy density reaches 1524 Wh kg−1 for carbonyl-bridged tri (3,5-pyrimidyl) borane, 50\% higher than in the inorganic reference material LiCoO2, rendering N-functionalized CBHTs promising organic cathode materials for LIBs. The investigation reveals the underlying structure-performance relationship of conjugated carbonyl compounds and sheds new lights for the rational design of redox-active organic molecules for high-performance lithium ion batteries (LIBs).

Keywords: carbonyl-bridged heterotriangulenes; cathode materials; first-principles calculations; high redox-potential; lithium-ion batteries

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38377
Publ.-Id: 38377


Modified Diglycolamide Resin: Characterization and Potential Application for Rare Earth Element Recovery

Romero, J.; Tabelin, C. B.; Park, I.; Alorro, R. D.; Zoleta, J.; Silva, L. C.; Arima, T.; Igarashi, T.; Mhandu, T.; Ito, M.; Happel, S.; Hiroyoshi, N.

Characterization of diglycolamide resin using XRF, SEM, XPS, FTIR.

Keywords: RARE EARTH ELEMENTS; EXTRACTION CHROMATOGRAPHY; ION-EXCHANGE RESIN; ADSORPTION; CRITICAL METALS

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38376
Publ.-Id: 38376


Unveiling Pseudo-Inert Basal Plane for Electrocatalysis in 2D Semiconductors: Critical Role of Reversal-Activation Mechanism

Zang, Y.; Wu, Q.; Wang, S.; Huang, B.; Dai, Y.; Heine, T.; Ma, Y.

Abstract Partially occupied orbitals play a pivotal role in enhancing the performance of electrocatalyst by facilitating electron acceptance and donation, thus enabling the activation of molecular bonds. According to this principle, the basal plane of most 2D semiconductors is inert for electrocatalysis because of the fully occupied orbitals at the surface. Here, taking monolayer CrX (X = P, As, Sb) and Cr2PY (Y = As, Sb) as examples and through first-principles calculations, it is revealed that even with fully occupied surface orbitals, the basal planes exhibit remarkable catalytic activity for the nitrogen oxide reduction reaction (NORR). This leads to the concept of the pseudo-inert electrocatalyst. The underlying physics behind such pseudo-inert character can be attributed to the reversal-activation mechanism: contrary to conventional expectations, the adsorbed NO molecule reversely triggers the activity of the inert basal plane first, and then the basal plane activates NO molecules, forming the intriguing “Reversal Activation-Transfer-Donation-Backdonation” process. This study further predicts that such pseudo-inert character can demonstrate many distinctive properties, for example, it can introduce a novel type of surface catalysis, one that selectively targets radicals possessing an inherent dipole moment such as NO. The explored phenomena and insights greatly enrich the realms of electrocatalysis and 2D materials.

Keywords: 2D semiconductor; First-principles calculation; NO reduction reaction; Pseudo-inert electrocatalyst; Reversal-activation mechanism

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38375
Publ.-Id: 38375


UTe2 microfabrication and high field experiments

Helm, T.

es hat kein aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences) (Online presentation)
    ANR-project SCATE Kickoff Meeting, 15.08.2023, Grenoble, France

Permalink: https://www.hzdr.de/publications/Publ-38374
Publ.-Id: 38374


Field-induced compensation of magnetic exchange as the origin of superconductivity above 40 T in UTe2

Helm, T.

es hat kein aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences) (Online presentation)
    Institute for Material Research, 27.04.2023, Tokyo, Japan

Permalink: https://www.hzdr.de/publications/Publ-38373
Publ.-Id: 38373


High-field superconductivity in UTe2

Helm, T.

es hat kein aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences)
    Condensed Matter Seminar, 24.02.2023, Bristol, United Kingdom

Permalink: https://www.hzdr.de/publications/Publ-38372
Publ.-Id: 38372


High-field superconductivity in UTe2

Helm, T.

es hat kein aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences)
    784. WE-Heraeus Seminar on Microstructure, Magnetic and Electronic Ordering. Interplay and Interactions, 16.-19.04.2023, Bad Honnef, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38371
Publ.-Id: 38371


Data publication: Analysis of loss of flow without scram test in the FFTF reactor – Neutronics data

Nikitin, E.; Fridman, E.; Ponomarev, A.

Neutronics models of the FFTF Cycle 8C core for LOFWOS Test #13, created using Serpent and DYN3D codes, along with the benchmark results, cross section data, burnup and decay heat calculations.

Keywords: SFR; Serpent; DYN3D; neutronics benchmark; homogenized cross section

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38370
Publ.-Id: 38370


THz resonance spectroscopy in high magnetic fields

Zvyagin, S.

es hat kein aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences)
    The Combination of High Magnetic Fields and Free Electron Lasers, 14.-15.06.2023, Nijmegen, Niederlande

Permalink: https://www.hzdr.de/publications/Publ-38369
Publ.-Id: 38369


Exploring semi-supervised generation of mineral tables for automated mineralogy systems

Pereira, L.; Tolosana Delgado, R.; Thiele, S. T.; Japarov, R.; Frenzel, M.; Bachmann, K.; Gutzmer, J.

The quality of results obtained by a scanning electron microscope-based automated mineralogy systems strongly depend on the project-specific library of spectra of the minerals considered to form the samples analysed, the mineral table. Mineral tables can be selected from existing universal libraries according to the expected or suspected minerals, and/or can be constructed based on spectra collected in the samples of a specific project. One can prefer extense mineral tables to enhance the chances of capturing variations in chemical composition of specific minerals; or else smaller, compact mineral tables to reduce misclassification. No general, perfect balance within generality-specificity or extension-compaction exists, so that users end up interactively and iteratively building the spectral library for each project in tedious steps of adding and removing mineral spectral candidates. This process is also project- and ore-specific. While some automated mineralogy devices provide operating modes for automatically constructing mineral lists throughout a measurement, these commonly offer only limited settings and are not clear about the data processing steps.

The goal of this contribution is to compare the performance of several components of a strategy to automatically construct automated mineralogy mineral lists - making use of several machine learning algorithms, for the specific case of dataset collected with the Mineral Liberation Analyser (MLA). The strategy has five steps: (1) preliminary data transformation, (2) dimension reduction, (3) endmember detection, (4) phase detection, and (5) unmixing.

For each of these steps, several options were tested. These included for data transformation peak extraction and Box-Cox transformations, which at the same time embraces logarithm/log-ratio transformations, square root transformations and the identity transformation. Regarding dimension reduction, principal component analysis and minimum-maximum autocorrelation factors were tested. In step three, we considered QHull convex hull detection, and N-FINDER, a conventional linear endmember detection method. In step four, the goal is to find the groups of spectra that can be identified with the members of the mineral table, not all of them being necessarily endmembers. Algorithms tested here correspond to model-free unsupervised classification algorithms, such as k-means, hyerarchical clustering methods and topological spectral clustering among other. Finally, in step five we tried several sparse and unconstrained linear unmixing algorithms. This unmixing was done within the sample of spectra forming the training data only in order to determine the number of necessary groups (or clusters) to extract from step four, as the actual final phase attribution will be done by the MLA software for the whole project after delivering the mineral table. The strategy presented here offers not only improvements to the workflow of scanning electron microscope-based automated mineralogy systems but also is a step stone for compiling mineral lists in analytical devices such as µX-Ray Fluorescence automated mineralogy, where spectra mixing is a bigger issue.

  • Lecture (Conference)
    17th SGA Biennial Meeting, 28.08.-01.09.2023, Zürich, Schweiz

Permalink: https://www.hzdr.de/publications/Publ-38366
Publ.-Id: 38366


Ultrastrong Electron-Phonon Coupling in Uranium-Organic Frameworks Leading to Inverse Luminescence Temperature Dependence

Chen, D.-H.; Vankova, N.; Jha, G.; Yu, X.; Wang, Y.; Lin, L.; Kirschhöfer, F.; Greifenstein, R.; Redel, E.; Heine, T.; Wöll, C.

Electron-phonon interactions, crucial in condensed matter, are rarely seen in Metal-Organic Frameworks (MOFs). Detecting these interactions typically involves analyzing luminescence in lanthanide- or actinide-based compounds. Prior studies on Ln- and Ac-based MOFs at high temperatures revealed additional peaks, but these were too faint for thorough analysis. In our research, we fabricated a high-quality, crystalline uranium-based MOF (KIT-U-1) thin film using a layer-by-layer method. Under UV light, this film showed two distinct 'hot bands,' indicating a strong electron-phonon interaction. At 77 K, these bands were absent, but at 300 K, a new emission band appeared with half the intensity of the main luminescence. Surprisingly, a second hot band emerged above 320 K, deviating from previous findings in rare-earth compounds. We conducted a detailed ab-initio analysis employing time-dependent density function theory to understand this unusual behaviour and to identify the lattice vibration responsible for the strong electron-phonon coupling. The KIT-U-1 film's hot-band emission was then utilized to create a highly sensitive, single-compound optical thermometer. This underscores the potential of high-quality MOF thin films in exploiting the unique luminescence of lanthanides and actinides for advanced applications.

Keywords: Metal-Organic Frameworks; PhotoluminescenceElectron-Phonon Coupling

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38365
Publ.-Id: 38365


Using halophilic bacteria as pyrite biodepressants in sulphide mineral bioflotation

Luque Consuegra, G.

Freshwater shortages causes challenges in mineral processing in Chile, especially in arid regions. As a result, froth flotation; a mineral process, is shifting usage of freshwater to seawater. This has consequences in the consumption of flotation reagents and decreasing the flotation efficiency. Biotechnological developments allow conceptualising the use of bacterial cells and their metabolites as bioreagents in flotation; classified as bioflotation.
In this thesis, 5 halophilic bacteria, namely, Halomonas boliviensis, Marinobacter spp., Halobacillus litoralis Hol-1, Marinococcus halophilus KOR-3 and Halomonas eurihalina P6-1 have been screened for the potential use as pyrite biodepressants at micro- and batch-scale flotation. The effect of bioconditioning minerals with these bacteria was studied using zeta potential, fluorescence microscopy and contact angle.
Experiments measuring zeta potential show the isoelectric point (IEP) of pyrite, chalcopyrite and molybdenite became more acidic post-bioconditioning. Fluorescence microscopy with Nile red; a hydrophobic stain, allowed for a method to visualize bacterial cells or collector potassium isopropyl xanthate (KIPX) on mineral particles of pyrite, chalcopyrite and molybdenite. Additionally contact angle experiments show that strains Halobacillus litoralis Hol-1, Marinococcus halophilus KOR-3 and Halomonas eurihalina P6-1 had an influence on the contact angle of pyrite and chalcopyrite, inducing changes in their hydrophobicity.
Microflotation experiments showed a decreased recovery of pyrite in presence of all strains, but notably, Halobacillus litoralis Hol-1 and Marinococcus halophilus KOR-3, also showed an increased recovery of chalcopyrite, making them ideal candidates as pyrite biodepressants. Halomonas eurihalina P6-1 showed low recoveries of both minerals, but a higher selectivity depressing more pyrite than chalcopyrite. Usage of autoclaved biomass from the three aforementioned strains in batch-flotation experiments resulted in the recovery of chalcopyrite improving, with a small decrease in the recovery of pyrite, overall showing a positive potential but not improving the system.
Halophilic bacteria such as the ones used in this study show an influence on the floatability of pyrite, which could be commercially exploited to substitute lime as a pyrite depressant. Furthermore, the work in this thesis focused on studying the effects of cells in artificial seawater, both at micro and batch-scales which brings the laboratory experiments a step closer to industrially relevant conditions.

  • Doctoral thesis
    TU Bergakademie Freiberg, 2022
    Mentor: Dr. Sabine Kutschke, Prof. Michaela Schlömann
    103 Seiten

Permalink: https://www.hzdr.de/publications/Publ-38363
Publ.-Id: 38363


Lanthanide ion-binding peptides as a natural solution for rare earth element separation and recovery

Claus, G.; Schönberger, N.; Drobot, B.; Lederer, F.

Due to their special properties, lanthanides (Ln) are of utmost importance in the current technological era – both in the present and in the future. Besides their indispensable contribution to high-tech products, they are also increasingly used in environmental technology. In recent years, attention has turned to alternative solutions such as the recycling of Ln from end-of-life products or wastewater from industry and mining. However, these contain only low concentrations of rare earth elements (REE), which are additionally very similar in their chemical and physical properties, so that the separation is cost-intensive and an efficient recovery still far away. Research and development of new recycling processes should change this and enable a cost-effective and environmentally friendly separation from electronic scrap and wastewater in order to conserve primary resources and make us independent of them. We are researching a promising approach for such a novel recycling technology and try to solve the separation problem using selective peptides. Immobilized on a suitable carrier material, this kind of biohybrid separation platform can finally be used for REE recovery.
By combining phage surface display technique with next generation sequencing and running parallel biopannings on target ion and immobilization material, we were able to enrich and identify peptide sequences showing an affinity for the europium ion (Eu3+). Most enriched and repetitive peptide variants in several biopannings with different elution types were characterized by time-resolved laser fluorescence spectroscopy and isothermal titration calorimetry with respect to their Eu3+ affinity. Calmodulin’s EF-hand 4 peptide serves as a reference system.

  • Poster
    3rd International Meeting on New Strategies in Bioremediation/Restoration Processes, 29.-30.06.2023, Muttenz, Schweiz

Permalink: https://www.hzdr.de/publications/Publ-38362
Publ.-Id: 38362


Estimation of weight window parameters based on recursive Monte Carlo approach for reactor shielding problems

Yadav, P.; Rachamin, R.; Konheiser, J.; Baier, S.

Weight window, a variance reduction tool, is often used to improve the performance of radiation shielding calculations. One common issue with the weight window is determining the optimal set of weight window parameters for solving deep penetration shielding problems. To address this issue, the recursive Monte-Carlo methodology has been used with the in-house TRAWEI code. The program is responsible for generating the optimal weight parameters in a single run with minimum computational time. This paper presents the results of a numerical test conducted using a simple reactor model to evaluate the performance of the developed weight generator program. The findings reveal that MCNP simulations utilizing TRAWEI-generated weight values exhibit significantly higher calculation efficiency compared to both analog simulation and MCNP simulation using weights generated by the existing MCNP weight window generator. Overall, the utilization of the RMC methodology has shown its potential to significantly contribute to deep penetration shielding calculations.

Keywords: Weight window; Shielding calculation; Deep penetration problem; RMC methodology; FOM

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38361
Publ.-Id: 38361


Inverting the Kohn-Sham equations with physics-informed machine learning

Martinetto, V.; Shah, K.; Cangi, A.; Pribram-Jones, A.

Electronic structure theory calculations offer an understanding of matter at the quantum level, complementing experimental studies in materials science and chemistry. One of the most widely used methods, density functional theory (DFT), maps a set of real interacting electrons to a set of fictitious non-interacting electrons that share the same probability density. Ensuring that the density remains the same depends on the exchange-correlation (XC) energy and, by a derivative, the XC potential. Inversions provide a method to obtain exact XC potentials from target electronic densities, in hopes of gaining insights into accuracy-boosting approximations. Neural networks provide a new avenue to perform inversions by learning the mapping from density to potential. In this work, we learn this mapping using physics-informed machine learning (PIML) methods, namely physics informed neural networks (PINNs) and Fourier neural operators (FNOs). We demonstrate the capabilities of these two methods on a dataset of one-dimensional atomic and molecular models. The capabilities of each approach are discussed in conjunction with this proof-of-concept presentation. The primary finding of our investigation is that the combination of both approaches has the greatest potential for inverting the Kohn-Sham equations at scale.

Keywords: Machine learning; Materials science; Electronic structure theory; Density functional theory; Neural networks; Physics-informed neural networks; Fourier neural operators; Inversion problems

Related publications

Permalink: https://www.hzdr.de/publications/Publ-38360
Publ.-Id: 38360


Improving the sustainability of critical raw materials extraction

Patil, A. B.

Improving the sustainability of critical raw
materials extraction

Keywords: critical raw materials; rare earth; process metallurgy; circular econoomy

  • Invited lecture (Conferences) (Online presentation)
    Improving the sustainability of critical raw materials extraction, 09.03.2023, Online, Germany

Permalink: https://www.hzdr.de/publications/Publ-38359
Publ.-Id: 38359


Data Management and Documentation at HZDR

Knodel, O.; Gruber, T.; Müller, S.; Juckeland, G.

This presentation provides insights into the development of the HZDR's in-house laboratory notebook for the documentation of scientific experiments. A special focus is placed on the integration of a variety of third-party systems in order to optimise the automated enrichment of data in the laboratory notebook and to facilitate documentation for scientists.

Keywords: Data management; Lab documentation; FAIR; Mediawiki

  • Open Access Logo Invited lecture (Conferences)
    FDM at TUD Core Facilities, 06.11.2023, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-38358
Publ.-Id: 38358


Data Policies and Infrastructure Services for FAIR Data: Cornerstones Along the Path and Lessons Learned

Knodel, O.

The talk addresses critical components of the FAIR data principles by examining the central role of data policies and infrastructure services. On the path to making data findable, accessible, interoperable and reusable (FAIR), the talk provides insights in the fundamental strategies for creating effective data policies and implementing infrastructure services that support these principles. Drawing on real-world experiences at HZDR, this talk will provide actionable insights for advancing FAIR data practices in research domains and highlight the essential cornerstones on this transformative journey.

Keywords: data management; open science; data policy; data publication

  • Open Access Logo Invited lecture (Conferences)
    HELPMI Workshop, 13.-14.11.2023, Darmstadt, Germany

Permalink: https://www.hzdr.de/publications/Publ-38356
Publ.-Id: 38356


Overarching Data Management Ecosystem HELIPORT

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

HELIPORT is a data management solution that aims at making the components and steps of the entire research experiment’s life cycle discoverable, accessible, interoperable and reusable according to the FAIR principles.
Among other information, HELIPORT integrates documentation, scientific workflows, and the final publication of the research results - all via already established solutions for proposal management, electronic lab notebooks, software development and devops tools, and other additional data sources. The integration is accomplished by presenting the researchers with a high-level overview to keep all aspects of the experiment in mind, and automatically exchanging relevant metadata between the experiment’s life cycle steps.
Computational agents can interact with HELIPORT via a REST API that allows access to all components, and landing pages that allow for export of digital objects in various standardized formats and schemas. An overall digital object graph combining the metadata harvested from all sources provides scientists with a visual representation of interactions and relations between their digital objects, as well as their existence in the first place. Through the integrated computational workflow systems, HELIPORT can automate calculations using the collected metadata.
By visualizing all aspects of large-scale research experiments, HELIPORT enables deeper insights into a comprehensible data provenance with the chance of raising awareness for data management.

Keywords: data management; data provenance; Heliport; HMC

  • Open Access Logo Invited lecture (Conferences)
    1st Workshop on Open Science at GSI/FAIR 2023, 19.-20.10.2023, Darmstadt, Germany

Permalink: https://www.hzdr.de/publications/Publ-38355
Publ.-Id: 38355


Coherent Magnons with Giant Nonreciprocity at Nanoscale Wavelengths

Gallardo, R. A.; Weigand, M.; Schultheiß, K.; Kakay, A.; Mattheis, R.; Raabe, J.; Schütz, G.; Deac, A. M.; Lindner, J.; Wintz, S.

Non-reciprocal wave propagation arises in systems with broken time-reversal symmetry and is key to the functionality of devices, such as isolators or circulators, in microwave, photonic and acoustic applications. In magnetic systems, collective wave excitations known as magnon quasiparticles so far yielded moderate non-reciprocities, mainly observed by means of incoherent thermal magnon spectra, while their occurrence as coherent spin waves (magnon ensembles with identical phase) is yet to be demonstrated. Here, we report the direct observation of strongly non-reciprocal propagating coherent spin waves in a patterned element of a ferromagnetic bilayer stack with antiparallel magnetic orientations. We use time-resolved scanning transmission x-ray microscopy (TR-STXM) to directly image the layer-collective dynamics of spin waves with wavelengths ranging from 5 µm down to 100 nm emergent at frequencies between 500 MHz and 5 GHz. The experimentally observed non-reciprocity factor of these counter-propagating waves is greater than 10 with respect to both group velocities and specific wavelengths. Our experimental findings are supported by the results from an analytic theory and their peculiarities are further discussed in terms of caustic spin-wave focusing.

Keywords: spin wave; magnon; non-reciprocity; magnetic vortex; scanning transmission X-ray microscopy; caustics

Related publications

Permalink: https://www.hzdr.de/publications/Publ-38354
Publ.-Id: 38354


End-of-life perspective for advanced energy storage, mobility and electronics technology materials: a gateway to a sustainable circular economy

Patil, A. B.; Gutzmer, J.

The world is witnessing unprecedented advances in the field of renewable energy generation, storage,
electrical mobility, and digital technologies. These developments are necessary to achieve our
ambitions of becoming a green and sustainable society that retains economic prosperity. Behind the
scenes this transition is enabled by a multitude of increasingly complex materials marked by impressive
optoelectronic and/ magnetic properties. Not only does the complexity of materials increase, but also
similar is true for the compositional architecture of machines, gadgets and installations. This is
combined with an ever-increasing speed with which advanced technologies penetrate global markets
and the often very limited life span / planned obsolence of many advanced technologies. Together,
these factors yield a rapidly increasing volume of waste materials of complex composition. Such
complex waste materials do not only contain a vast variety of valuable resources but, if left untreated,
may cause great harm to humans and the environment. It is, therefore, obvious that we need no less
than a paradigm shift. EoL products should be regarded not as waste but as valuable secondary
resource. Technological solutions are urgently needed to drive the transition towards holistic recycling
concepts.
The simple, holistic and yet sustainable answer to all these questions is the adoption of circular
economy strategies. This talk will present the opportunities and challenges in management of
advanced materials with end-of-life perspective. How the fundamental understanding of materials
properties and quantities is necessary in viable circular economy process developments and
implementation. It will be complemented by select examples of technologies developed for the
recycling of relevant materials and its materials safety-related implications.

Keywords: Advanced materials; e-wastes; rare metals; circular economy; safety; process metallurgy

  • Open Access Logo Contribution to proceedings
    Advanced Materials Safety 2023, 08.-10.11.2023, Saarbrücken, Germany
    Advanced Materials Safety 2023, Abstract book, Saarbrücken: Leibniz Research Alliance, 10.5281/zenodo.10069640, 8
    DOI: 10.5281/zenodo.10069640
  • Open Access Logo Invited lecture (Conferences)
    Advanced materials safety 2023, 08.-10.11.2023, Saarbrücken, Germany
    DOI: 10.5281/zenodo.10069640

Permalink: https://www.hzdr.de/publications/Publ-38353
Publ.-Id: 38353


The effect of synthesis conditions on the in situ grown MIL-100(Fe)-chitosan beads: Interplay between structural properties and arsenic adsorption

Joseph, J.; Väisänen, A.; Patil, A. B.; Lahtinen, M.

Efficient sequestration of arsenic from drinking water is a global need. Herein we report eco-friendly porous hybrid adsorbent beads for removal of arsenic, through in situ synthesis of MIL-100(Fe) in the chitosan solvogel. To understand the structural vs. performance correlation, series of hybrid adsorbents were synthesized by modulating synthesis conditions like temperature, crystallization time, and concentration. Adsorbents were investigated using PXRD, FT-IR, SEM, and ICP-OES. Intriguing correlation between crystallinity and adsorption performance was observed as low and high crystalline MIL-100(Fe)-chitosan (ChitFe5 and ChitFe7, respectively) exhibited exceptional adsorption towards As5+ by removing it from water with 99% efficiency, whereas for As3+ species removal of about 85% was afforded. Adsorption isotherms indicated that increase in crystallinity (ChitFe5 -> ChitFe7), adsorption capacities of As5+ and As3+ increased from 23.2 to 64.5, and from 28.1 to 35.3 mg/g, respectively. Selectivity tests of the adsorbents towards As5+ and As3+ over competitive anions in the equimolar competitive systems having nitrates, sulfates, and carbonates demonstrated that the performance of the absorbents was fully maintained, relative to the control system. Through this study a highly selective and efficient adsorbent for arsenic species is designed and a clear insight into the structural tuning and its effect on adsorption performance is provided.

Keywords: Metal-organic frameworks; Aerogels; Hybrid materials; Crystallinity; Arsenic

Permalink: https://www.hzdr.de/publications/Publ-38352
Publ.-Id: 38352


Surfactant-based enrichment of rare earth elements from NdFeB magnet e-waste: Optimisation of cloud formation and rare earths extraction

Patil, A. B.; Thalmann, N.; Torrent, L.; Tarik, M.; Struis, R. P. W. J.; Ludwig, C.

Appropriate waste and resource management are essential for a sustainable circular economy with reduced environmental impact. With critical resources, e-waste may serve as indirect raw material. For example, with NdFeB permanent magnets, Neodymium (Nd) and the co-present Dysprosium (Dy) are critical rare earth elements (REEs). However, there exists no economically viable technology for recycling them from electronic waste (e-waste). Here, a method is presented based on cloud point extraction (CPE). The work involves basic complexation chemistry in a cloud medium with pure REE salts, as well as, with real NdFeB-magnets (nearly 28% REE content by weight) from an old hard disk drive (5.2 g magnet in a 375 g HDD). High extraction efficiency (>95%) was achieved for each REE targeted (Nd, Dy, Praseodymium (Pr)). With the magnet waste, the cloud phase did hardly contain any Nickel (Ni), Cobalt (Co), or Boron (B), but some Aluminium (Al) and Iron (Fe). Dynamic light scattering results indicated aggregation of ligand-surfactant micelles with the cloud phase. The preconcentrated products can be used for new Nd magnet manufacturing or further enriched using established transition metal removal techniques. Reuse of solvent, low chemical inventory demand, and using non-inflammable, non-volatile organic extractants promise safe large-scale operation, low process costs, and less environmental impact than using hydrometallurgical methods used with urban or primary mining.

Keywords: Circular economy; Sustainability; Rare earths; Recycling; E-waste; Cloud point extraction; Resource management; Green process; Critical raw materials

Permalink: https://www.hzdr.de/publications/Publ-38350
Publ.-Id: 38350


Operating experience with ELBE SRF gun II

Arnold, A.

At the electron accelerator for beams with high brilliance and low emittance (ELBE), the second version of a superconducting radio-frequency (SRF) photoinjector was brought into operation in 2014. After a period of commissioning, a gradual transfer to routine operation took place in 2017, so that now more than 1800h of user beam are generated every year. Since the commission, a total of 24 cathodes (2 Cu, 12 Mg, 10 Cs2Te) have been used, without observing serious cavity degradation. The contribution summarized commissioning and operational experience of the last years, with special emphasis on SRF properties but also on specialties such as dark current and multipacting that are directly linked to the integration of a normal conducting cathode into the SRF cavity.

Keywords: SRF gun; photocathode; electron source; injector; ELBE

Related publications

  • Lecture (others)
    Annual Gun Cluster Meeting 2023, 08.11.2023, Berlin, Germany

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38349
Publ.-Id: 38349


Data publication: Massively Parallel Implementation of Gradients within the Random Phase Approximation: Application to the Polymorphs of Benzene

Stein, F.; Hutter, J.

original input and output files to create tables and figures as described in the corresponding paper.

Keywords: density-functional theory; random phase approximation; polymorphs; benzene; high performance computing; nuclear gradients; PASC

Related publications

Permalink: https://www.hzdr.de/publications/Publ-38348
Publ.-Id: 38348


Data repository for "Mechanistic insight on water dissociation on pristine low-index TiO$_2$ surfaces from machine learning molecular dynamics simulations"

Zeng, Z.; Wodaczek, F.; Liu, K.; Stein, F.; Hutter, J.; Chen, J.; Cheng, B.

This repository contains all input files and the thereby generated raw data used to generate figures and other results described in the corresponding paper.

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38347
Publ.-Id: 38347


Data publication: Disordered enthalpy–entropy descriptor for high-entropy ceramics discovery

Divilov, S.; Eckert, H.; Hicks, D.; Oses, C.; Toher, C.; Friedrich, R.; Esters, M.; Mehl, M. J.; Zettel, A. C.; Lederer, Y.; Zurek, E.; Maria, J.-P.; Brenner, D. W.; Campilongo, X.; Filipović, S.; Fahrenholtz, W. G.; Ryan, C. J.; Desalle, C. M.; Crealese, R. J.; Wolfe, D. E.; Calzolari, A.; Curtarolo, S.

dataset to calculate DEED; code of the algorithm to perform the DEED calculation

Related publications

Permalink: https://www.hzdr.de/publications/Publ-38346
Publ.-Id: 38346


Disordered enthalpy–entropy descriptor for high-entropy ceramics discovery

Divilov, S.; Eckert, H.; Hicks, D.; Oses, C.; Toher, C.; Friedrich, R.; Esters, M.; Mehl, M. J.; Zettel, A. C.; Lederer, Y.; Zurek, E.; Maria, J.-P.; Brenner, D. W.; Campilongo, X.; Filipović, S.; Fahrenholtz, W. G.; Ryan, C. J.; Desalle, C. M.; Crealese, R. J.; Wolfe, D. E.; Calzolari, A.; Curtarolo, S.

The need for improved functionalities in extreme environments is fuelling interest
in high-entropy ceramics. Except for the computational discovery of high-entropy
carbides, performed with the entropy-forming-ability descriptor, most innovation
has been slowly driven by experimental means. Hence, advancement in the field
needs more theoretical contributions. Here we introduce disordered enthalpy–
entropy descriptor (DEED), a descriptor that captures the balance between
entropy gains and enthalpy costs, allowing the correct classification of functional
synthesizability of multicomponent ceramics, regardless of chemistry and structure.
To make our calculations possible, we have developed a convolutional algorithm that
drastically reduces computational resources. Moreover, DEED guides the experimental
discovery of new single-phase high-entropy carbonitrides and borides. This work,
integrated into the AFLOW computational ecosystem, provides an array of potential
new candidates, ripe for experimental discoveries.

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38344
Publ.-Id: 38344


H-NMR of the spin-1/2 sawtooth chain material atacamite

Kotte, T.

es hat kein aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences)
    Magnetic Resonance of Correlated Electron Materials Workshop, 17.-23.09.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38343
Publ.-Id: 38343


Electron Spin Resonance of the Interacting Spinon Liquid

Povarov, K.

es hat kein aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences)
    Magnetic Resonance of Correlated Electron Materials Workshop, 17.-23.09.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38342
Publ.-Id: 38342


Magnetische Kühlung: Vom Material hin zum magnetokalorischen Kühlaggregat

Gottschall, T.

es hat kein aussagekräftiges Abstract vorgelegen

  • Invited lecture (Conferences)
    Deutscher Kälte- und Klimatechnischer Verein, 24.07.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38341
Publ.-Id: 38341


Materials with first-order transition and inverse magnetocaloric effect and their peculiarities

Salazar Mejia, C.

es hat keine aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences) (Online presentation)
    Workshop on i-Caloric Effects 2023, 26.-27.04.2023, Rio de Janeiro, Brazil

Permalink: https://www.hzdr.de/publications/Publ-38340
Publ.-Id: 38340


Caracterización de materiales magneto-calóricos utilizando campos magnéticos pulsados

Salazar Mejia, C.

es hat kein aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences) (Online presentation)
    3ra Escuela Colombiana de Magnetismo, 13.-17.11.2023, Manizales, Colombia

Permalink: https://www.hzdr.de/publications/Publ-38339
Publ.-Id: 38339


Massively Parallel Implementation of Gradients within the Random Phase Approximation: Application to the Polymorphs of Benzene

Stein, F.; Hutter, J.

The Random-Phase approximation (RPA) provides an appealing framework for semi-local density functional theory. In its Resolution-of-the-Identity (RI) approach it is a very accurate and more cost-effective method than most other wavefunction-based correlation methods. For widespread applications efficient implementations of nuclear gradients for structure optimizations and data sampling of machine learning approaches is required. We report a well scaling implementation of RI-RPA nuclear gradients on massively parallel computers. The approach is applied to two polymorphs of the benzene crystal obtaining very good cohesive and relative energies. Different correction and extrapolation schemes are investigated for further improvement of the results and estimations of error bars.

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38338
Publ.-Id: 38338


Pulsed-field user facility HLD-EMFL

Zherlitsyn, S.

es hat kein aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences)
    1000 T science workshop, 04.-06.12.2023, Tokyo, Japan

Permalink: https://www.hzdr.de/publications/Publ-38337
Publ.-Id: 38337


Pulsed magnetic fields for science

Zherlitsyn, S.

es hat kein aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences)
    ISABEL, MagX workshop, 07.-09.11.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38336
Publ.-Id: 38336


Mechanistic insight on water dissociation on pristine low-index TiO2 surfaces from machine learning molecular dynamics simulations

Zeng, Z.; Wodaczek, F.; Liu, K.; Stein, F.; Hutter, J.; Chen, J.; Cheng, B.

Water adsorption and dissociation processes on pristine low-index TiO2 interfaces are important but poorly understood outside the well-studied anatase (101) and rutile (110). To understand these, we construct three sets of machine learning potentials that are simultaneously applicable to various TiO2 surfaces, based on three density-functional-theory approximations. Here we show the water dissociation free energies on seven pristine TiO2 surfaces, and predict that anatase (100), anatase (110), rutile (001), and rutile (011) favor water dissociation, anatase (101) and rutile (100) have mostly molecular adsorption, while the simulations of rutile (110) sensitively depend on the slab thickness and molecular adsorption is preferred with thick slabs. Moreover, using an automated algorithm, we reveal that these surfaces follow different types of atomistic mechanisms for proton transfer and water dissociation: one-step, two-step, or both. These mechanisms can be rationalized based on the arrangements of water molecules on the different surfaces. Our finding thus demonstrates that the different pristine TiO2 surfaces react with water in distinct ways, and cannot be represented using just the low-energy anatase (101) and rutile (110) surfaces.

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38335
Publ.-Id: 38335


Selected acoustic effects in the Solid State

Zherlitsyn, S.

es hat kein aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences)
    ISABEL Regional Meeting, 06.-08.09.2023, Prague, Czech Republic

Permalink: https://www.hzdr.de/publications/Publ-38334
Publ.-Id: 38334


Spin-orbital liquid state and liquid-gas metamagnetic transition on a pyrochlore lattice

Zherlitsyn, S.

es hat kein aussagefähiges Abstract vorgelegen

  • Invited lecture (Conferences)
    III International Conference "Condensed Matter & Low Temperature Physics 2023", 05.-11.06.2023, Kharkiw, Ukaine

Permalink: https://www.hzdr.de/publications/Publ-38333
Publ.-Id: 38333


Studying the Fulde-Ferrell-Larkin-Ovchinnikov order parameter in quasi-2D organic superconductors

Kotte, T.

es hat kein aussagefähiger Abstract vorgelegen

  • Invited lecture (Conferences)
    DPG Frühjahrstagung, 26.-31.03.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38332
Publ.-Id: 38332


Time-resolved optical shadowgraphy of solid hydrogen jets as a testbed to benchmark particle-in-cell simulations

Yang, L.; Huang, L.; Assenbaum, S.; Cowan, T.; Göthel, I.; Göde, S.; Kluge, T.; Rehwald, M.; Pan, X.; Schramm, U.; Vorberger, J.; Zeil, K.; Ziegler, T.; Bernert, C.

Particle-in-cell (PIC) simulations are a widely-used tool to model kinetics-dominated plasmas in ultrarelativistic laser-solid interactions (dimensionless vectorpotential a0 > 1). However, interactions approaching subrelativistic laser intensities (a0 ≲ 1) are governed by correlated and collisional plasma physics, calling for benchmarks of available modeling capabilities and the establishment of standardized testbeds. Here, we propose such a testbed to experimentally benchmark PIC simulations of laser-solid interactions using a laser-irradiated micron-sized cryogenic hydrogen-jet target. Time-resolved optical shadowgraphy of the expanding plasma density, complemented by hydrodynamics and ray-tracing simulations, is used to determine the bulk-electron-temperature evolution after laser irradiation. We showcase our testbed by studying isochoric heating of solid hydrogen induced by laser pulses with a dimensionless vectorpotential of a0 ≈ 1. Our testbed reveals that the initial surface-density gradient of the target is decisive to reach quantitative agreement at 1 ps after the interaction, demonstrating its suitability to benchmark controlled parameter scans at subrelativistic laser intensities.

Permalink: https://www.hzdr.de/publications/Publ-38331
Publ.-Id: 38331


Local magnetic patterning of nanostructures using cobalt and dysprosium focused ion beams

Lenz, K.; Pablo-Navarro, J.; Klingner, N.; Hlawacek, G.; Kakay, A.; Bischoff, L.; Narkovic, R.; Mazarov, P.; Hübner, R.; Meyer, F.; Pilz, W.; Lindner, J.

We present results for direct maskless magnetic patterning of ferromagnetic nanostructures using a special liquid metal alloy ion source for focused ion beam (FIB) systems. We used a Co36Nd64 alloy as the FIB source [1]. A Wien mass filter allows for quick switching between the ion species in the alloy without changing the FIB source. A 5000×1000×50 nm3 permalloy strip served as the sample. Using the FIB we implanted a 300-nm-wide track with Co ions (see Fig.1). We observed the Co-induced changes by measuring the sample with microresonator ferromagnetic resonance before and after the implantation. Structures as small as 30 nm can be implanted up to a concentration of 10 % near the surface. Such lateral resolution is hard to reach for other lithographic methods. This allows for easy magnetic modification of edge-localized spin waves.
In another set of samples, we implanted Dy ions to locally increase the damping in a stripe pattern of ~120-nm-wide strips with 400 nm periodicity on a total area of 1×1 mm². Thus, the Gilbert damping parameter can be easily increased by one order of magnitude with a lateral resolution of about 100 nm.
In contrast to electron beam lithography in combination with broad-beam ion implantation, the maskless FIB process does not require the cumbersome and difficult removal of the ion-hardened resist if optical measurements like BLS or TR-MOKE are needed.

Keywords: Nanostructuctures; Focused Ion beams; ferromagnetic resonance; microresonators; magnetism

Related publications

  • Lecture (Conference)
    XII Latin American Workshop on Magnetism and Magnetic Materials, 16.-20.10.2023, Puerto Varas, Chile

Permalink: https://www.hzdr.de/publications/Publ-38329
Publ.-Id: 38329


Natural and synthetic plagioclases: Surface charge characterization and sorption of trivalent lanthanides (Eu) and actinides (Am, Cm)

Lessing, J.; Neumann, J.; Lützenkirchen, J.; Bok, F.; Moisei-Rabung, S.; Schild, D.; Brendler, V.; Stumpf, T.; Schmidt, M.

The environmental fate of radiotoxic actinides is controlled by their interactions with feldspars. Here, the sorption of trivalent minor actinides (Am, Cm) and their rare earth analogue Eu onto synthetic pure Ca-feldspar (anorthite) and natural plagioclases of different Ca contents is investigated, covering ranges of [M3+] (52 nM–10 μM), solid-liquid ratios (1–3 g/L), pH (3–9), and ionic strengths (0.01–0.1 M NaCl) under both ambient and CO2-free conditions. The zeta potential shows an unusual increase and charge reversal between pH 4 and 7 with increasing amount of Ca and Al in the feldspar crystal lattice, which is likely connected to adsorption and/or surface precipitation of dissolved Al3+. Streaming potential measurements yield (de)protonation constants for anorthite surface sites of log K- = -6.94 ± 0.38 and log K+ = +6.84 ± 0.38. Batch sorption data shows strong immobilization of M3+ by plagioclases at mildly acidic and basic pH. Time-resolved laser fluorescence spectroscopy using Cm indicates the formation of an inner-sphere complex and its two hydrolyzed forms. The complex reactivity of dissolved Al3+ at the plagioclase-water interface severely complicated the development of a surface complexation model, emphasizing the need for additional research in this area.

Keywords: Ca-feldspar; Anorthite; Sorption; Trivalent metal ions; TRLFS; Surface Complexation Model; Charge Reversal

Permalink: https://www.hzdr.de/publications/Publ-38328
Publ.-Id: 38328


Concepts and challenges in the metallurgical processing of marine resources

Kelly, N.

summary of metallurgical processes commonly used in the industry from sulfide concentrates to the metal products; based on this, the current technological approaches and emerging challenges in the metal recovery from marine sources will be discussed

  • Lecture (Conference)
    Sino-German Workshop/Symposium: Deep-sea mining of massive sulfides: balancing impacts on biodiversity and ecosystem, technological challenges and law of the sea, 18.-22.09.2023, Changsha, China

Permalink: https://www.hzdr.de/publications/Publ-38327
Publ.-Id: 38327


Next-generation Radioimmunotherapy using CAR T Cells Combined with Photon vs. Proton vs. Carbon Irradiation

Arndt, C.; Schlegel, J.

Next-generation Radioimmunotherapy using CAR T Cells Combined with Photon vs. Proton vs. Carbon Irradiation

  • Invited lecture (Conferences) (Online presentation)
    National Center for Radiation Oncology, 5th Scientific Retreat, 06.05.2023, Heidelberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38323
Publ.-Id: 38323


Bone marrow-derived mesenchymal stromal cells obstruct AML-targeting CD8+ clonal effector and CAR T cell function while promoting a senescence-associated phenotype

Towers, R.; Trombello, L.; Fusenig, M.; Tunger, A.; Baumann, A.-L.; Savoldelli, R.; Wehner, R.; Fasslrinner, F.; Arndt, C.; Dazzi, F.; von Bonin, M.; Feldmann, A.; Bachmann, M.; Wobus, M.; Schmitz, M.; Bornhäuser, M.

Bone marrow mesenchymal stromal cells (MSCs) have been described as potent regulators of T cell function, though whether they could impede the effectiveness of immunotherapy against acute myeloid leukemia (AML) is still under investigation. We examine whether they could interfere with the activity of leukemia-specific clonal cytotoxic T lymphocytes (CTLs) and chimeric antigen receptor (CAR) T cells, as well as whether the immunomodulatory properties of MSCs could be associated with the induction of T cell senescence. Co-cultures of leukemia-associated Wilm’s tumour protein 1 (WT1)- and Tyrosine-protein kinase transmembrane receptor 1 (ROR1)-reactive CTLs and of CD123-redirected switchable CAR T cells were prepared in the presence of MSCs and assessed for cytotoxic potential, cytokine secretion and proliferation. T cell senescence within functional memory sub-compartments was investigated for the senescence-associated phenotype CD28-CD57+ using unmodified peripheral blood mononuclear cells (PBMCs). We describe inhibition of expansion of AML-redirected switchable CAR T cells by MSCs via indoleamine 2,3-dioxygenase 1 (IDO-1) activity, as well as reduction of interferon gamma (IFNγ) and interleukin 2 (IL-2) release. In addition, MSCs interfered with the secretory potential of leukemia-associated WT1- and ROR1-targeting CTL clones, inhibiting the release of IFNγ, tumour necrosis factor alpha (TNFα), and IL-2. Abrogated T cells were shown to retain their cytolytic activity. Moreover, we demonstrate induction of a CD28loCD27loCD57+KLRG1+ senescent T cell phenotype by MSCs. In summary, we show that MSCs are potent modulators of anti-leukemic T cells, and targeting their modes of action would likely be beneficial in a combinatorial approach with AML-directed immunotherapy.

Permalink: https://www.hzdr.de/publications/Publ-38322
Publ.-Id: 38322


Data publication: The spatial association of accessory minerals with biotite in granitic rocks from the South Mountain Batholith, Nova Scotia, Canada

Clarke, B. D.; Renno, A.; Hamilton, D. C.; Gilbricht, S.; Bachmann, K.

Data publication: The spatial association of accessory minerals with biotite in granitic rocks from the South Mountain Batholith, Nova Scotia, Canada

D. Barrie Clarke; Axel D. Renno; David C. Hamilton; Sabine Gilbricht; Kai Bachmann

Related to publication Geosphere (2022) 18 (1): 1–18; https://doi.org/10.1130/GES02339.1

We use mineral liberation analysis (MLA) to quantify the spatial association of 15,118 grains of accessory apatite, monazite, xenotime, and zircon with essential biotite, and clustered with themselves, in a peraluminous biotite granodiorite from the South Mountain Batholith in Nova Scotia (Canada). A random distribution of accessory minerals demands that the proportion of accessory minerals in contact with biotite is identical to the proportion of biotite in the rock, and the binary touching factor (percentage of accessory mineral touching biotite divided by modal proportion of biotite) would be ~1.00. Instead, the mean binary touching factors for the four accessory minerals in relation to biotite are: apatite (5.06 for 11,168 grains), monazite (4.68 for 857 grains), xenotime (4.36 for 217 grains), and zircon (5.05 for 2876 grains). Shared perimeter factors give similar values. Accessory mineral grains that straddle biotite grain boundaries are larger than completely locked, or completely liberated, accessory grains. Only apatite-monazite clusters are significantly more abundant than expected for random distribution. The high, and statistically significant, binary touching factors and shared perimeter factors suggest a strong physical or chemical control on their spatial association. We evaluate random collisions in magma (synneusis), heterogeneous nucleation processes, induced nucleation in passively enriched boundary layers, and induced nucleation in actively enriched boundary layers to explain the significant touching factors. All processes operate during the crystallization history of the magma, but induced nucleation in passively and actively enriched boundary layers are most likely to explain the strong spatial association of phosphate accessories and zircon with biotite. In addition, at least some of the apatite and zircon may also enter the granitic magma as inclusions in grains of Ostwald-ripened xenocrystic biotite.

This data repository contains the complete set of the respective MLA – measurements (Reference) including the raw data and the data analysis.

Keywords: accessory minerals; biotite; spatial association; boundary layer; synneusis; heterogeneous nucleation; automated mineralogy; MLA

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38321
Publ.-Id: 38321


The Utilization of Primary Amines for separation of HREEs from LREEs in Sulphate Media

Bastürkcü, E.; Kelly, N.; Stelter, M.; Yuce, A. E.; Timur, S. I.

In recent years, several studies have been conducted to improve the process steps of rare earth elements (REEs) production. Beneficiation & separation stages varies according to type and concentration of impurities. One of the most complex process can be the selective separation of rare earth elements from each other due to their similar physical and chemical properties. At industrial scale,msolvent extraction is the most common separation and enrichment technology for REEs.
The efficiency of solvent extraction depends on several factors. The selection of extractant strongly depends on the composition of the leachate. In sulphate media, carboxylic acids are preferred because of their high extraction rates. Furthermore, primary amines can be used for extraction of rare earths in sulphate media. In amine system, extraction follows a reverse order comparing to cationic extractants.
In the presented study, primary amine Primene 81-R was selected as an alternative extractant in order to investigate its potential for a highly selective separation of REEs. The separation of HREEs from LREEs was determined in dependence on pH and concentration of the extractant using a model solution consisting mainly of LREES (97% of the total REE content). In the extraction experiment, approximately 40-50% of LREE were extracted into the organic phase, while the extraction of HREEs was obtained to be only between 5-30% under these conditions. However, for further development of the solvent extraction process, optimization studies are ongoing.

Keywords: REEs; solvent extraction; primary amine; sulphate media

  • Lecture (Conference)
    EMC 2023 European Metallurgical conference, 11.-14.06.2023, Düsseldorf, Deutschland
  • Contribution to proceedings
    EMC 2023 - European Metallurgical Conference, 11.-14.06.2023, Düsseldorf, Deutschland
    The Utilization of Primary Amines for separation of HREEs from LREEs in Sulphate Media

Permalink: https://www.hzdr.de/publications/Publ-38320
Publ.-Id: 38320


Key technologies of ELBE SRF-Gun II: user operation experiences

Ryzhov, A.

A brief summary of user operation experiences with SRF-Gun II at ELBE (since 2014) with an emphasis on most recent results and an oulook.

Keywords: SRF; Photoinjector; Accelerator; Photcathode

  • Lecture (Conference)
    The 9th annual meeting of the programme "Matter and Technologies", 11.-12.10.2023, Karlsruhe, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38319
Publ.-Id: 38319


News from ELBE SRF-Gun group

Ryzhov, A.

An update on activities of ELBE SRF-Gun group

  • Lecture (Conference)
    PITZ Collaboration Meeting, 16.-17.05.2023, Zeuthen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38318
Publ.-Id: 38318


Field-induced phase transitions and anisotropic magnetic properties of the Kitaev-Heisenberg compound Na2Co2TeO6

Bera, A. K.; Yusuf, S. M.; Orlandi, F.; Manuel, P.; Bhaskaran, L.; Zvyagin, S.

Spin systems with honeycomb structures have recently attracted a great deal of attention in connection with the Kitaev quantum spin liquid state (QSL) predicted theoretically. One possible Kitaev QSL candidate is Na2Co2TeO6 realizing a honeycomb lattice of pseudospin 1/2. Field-dependent single-crystal neutron diffraction technique allows us to determine the microscopic spin-spin correlations across the field-induced phase transitions for H II a and H II a∗ in plane field directions. Our results reveal phase transitions, initially to a canted zigzag antiferromagnetic state at approximately 60 kOe, followed by a possible transition to a partially polarized state over the range 90–120 kOe, and finally to a field-induced fully polarized state above 120 kOe. We observe distinct field dependencies of the magnetic peak intensities for H II a and H II a∗. In addition, low-temperature electron spin resonance in magnetic fields H _ c yields a complete softening for one of the antiferromagnetic resonances at ∼40 kOe, revealing a field-induced phase transition. The present work thus provides insights into the field evolution of the important Kitaev-Heisenberg spin system Na2Co2TeO6.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38316
Publ.-Id: 38316


Explainable Machine Learning for Crop Recommendation from Agriculture Sensor Data- a New Paradigm

Das, S.; Chatterjee, S.

The dwindling agricultural earnings and decrease in crop yield in recent years due to improper crop selection and fluctuation/ uncertainty in weather necessitate proper machine learning-based analysis. Machine learning methods can potentially alleviate the predicament caused by the lack of appropriate soil testing, consultation, and bias in manual suggestion. This work attempted to comprehend the agricultural sensor data and weather conditions and formulated the task in terms of supervised classification. The work obtained accurate suggestions in the presence of missing data, noise, etc. by using advanced machine learning methods. But recommendation alone is insufficient to convince farmers and other stakeholders to adopt this approach. Hence, this paper introduced explainable machine learning to completely comprehend the decision-making process. This work quantified the importance of features, explained individual prediction outcomes, and uncovered the rationale for decisions. The work employed state-of-the-art local interpretable model-agnostic, post-hoc explanation methods to provide in-depth insights. The insights obtained from the explanations can help the farmers develop a knowledge base and assist the farmers in choosing the appropriate sensors for the task. The human interpretable analysis enables the farmers to obtain satisfactory yields in these ever-changing and extreme weather conditions and environmental degradation.

Keywords: Agricultural data analytics; Sensor data; Crop recommendation; Explainable machine learning

  • Contribution to proceedings
    2023 14th International Conference on Computing Communication and Networking Technologies (ICCCNT), 06.-08.07.2023, Delhi, India
    2023 14th International Conference on Computing Communication and Networking Technologies (ICCCNT), Delhi: IEEE, 979-8-3503-3509-5
    DOI: 10.1109/ICCCNT56998.2023.10308154

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38315
Publ.-Id: 38315


Dielectric Relaxation by Quantum Critical Magnons

Flavian, D.; Volkov, P. A.; Hayashida, S.; Povarov, K.; Gvasaliya, S.; Chandra, P.; Zheludev, A.

We report the experimental observation of dielectric relaxation by quantum critical magnons. Complex capacitance measurements reveal a dissipative feature with a temperature-dependent amplitude due to lowenergy lattice excitations and an activation behavior of the relaxation time. The activation energy softens close to a field-tuned magnetic quantum critical point at H = Hc and follows single-magnon energy for H > Hc, showing its magnetic origin. Our study demonstrates the electrical activity of coupled low-energy spin and lattice excitations, an example of quantum multiferroic behavior.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38314
Publ.-Id: 38314


Data publication: Preclinical evaluation of an ¹⁸F-labeled Nε-acryloyllysine piperazide for covalent targeting of transglutaminase 2

Wodtke, R.; Laube, M.; Hauser, S.; Meister, S.; Ludwig, F.-A.; Fischer, S.; Kopka, K.; Pietzsch, J.; Löser, R.

Data to PET, Biodistribution, Metabolism and cell uptake

Keywords: radiofluorination; liver microsomes; biodistribution; PET imaging; plasma clearance; pharmacokinetics; radiometabolites; defluorination

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38312
Publ.-Id: 38312


Ion implantation + sub-second annealing: a versatile route towards hyperdoped semiconductors

Zhou, S.

Doping allows us to modify semiconductor materials for desired electrical, optical and magnetic properties. The solubility limit is a fundamental barrier for dopants incorporated into a specific semiconductor. Hyperdoping refers to doping a semiconductor much beyond the corresponding solid solubility limit and often results in exotic properties. For example, B hyperdoped diamond reveals superconductivity and Mn hyperdoped GaAs represents a typical ferromagnetic semiconductor. Ion implantation followed by annealing is a well-established method to dope Si and Ge. This approach has been maturely integrated with the IC industry production line. However, being applied to hyperdoping, the annealing duration has to be shortened to millisecond or even nanosecond. The intrinsic physical parameters related to dopants and semiconductors (e.g. Solubility, diffusivity, melting point and thermal conductivity) have to be considered to choose the right annealing time regime. In this talk, we propose that ion implantation combined with flash lamp annealing in millisecond and pulsed laser melting in nanosecond can be a versatile approach to fabricate hyperdoped semiconductors. The examples include magnetic semiconductors [1-5] and chalcogen doped Si [6-10].

[1] M. Khalid, et al., Phys. Rev. B 89, 121301(R) (2014).

[2] S. Zhou, J. Phys. D: Appl. Phys. 48, 263001(2015).

[3] S. Prucnal, et al., Phys. Rev. B 92, 222407 (2015).

[4] Y. Yuan, et al., ACS Appl. Mater. Interfaces, 8, 3912 (2016).

[5] Y. Yuan, et al., Phys. Rev. Mater. 1, 054401 (2017).

[6] S. Zhou, et al., Sci. Reports 5, 8329(2015).

[7] M. Wang, et al., Phys. Rev. Applied. 10, 024054 (2018).

[8] M. Wang, et al., Phys. Rev. Applied. 11, 054039 (2019).

[9] M. Wang, et al., Phys. Rev. B 102, 085204 (2020)

[10] M. Wang, et al., Adv. Optical Mater. 9, 2001546 (2021).

Related publications

  • Lecture (others)
    Invited Seminar at Univ. Surrey, 03.05.2023, Guildford, UK

Permalink: https://www.hzdr.de/publications/Publ-38311
Publ.-Id: 38311


Ion beam modification for advanced semiconductor materials

Zhou, S.

Ion implantation followed by thermal annealing is a well-established method to dope semiconductors, e.g. Si and Ge. This approach has been maturely integrated with the integrated circuit (IC) industry production line for area- and depth-selective n/p doping as well as for lifetime engineering [1]. As a national lab in Germany, our center is running an Ion Beam Center for materials research [2]. It is open free to the international community for fundamental research based on a proposal system. Within the research department “Semiconductor Materials”, we are running unique annealing methods, including millisecond flash lamp annealing and nanosecond pulsed laser melting, to repair the ion beam induced damage and to activate the dopants [3, 4]. I will show diverse research examples by using ion beam to modify semiconductor materials. They include pushing the doping limits in semiconductors well above the solubility limits [5-7], functionalizing 2D materials [8] and creating color centers for quantum technologies [9, 10].

[1] Ye Yuan, S. Zhou and X. Wang, Modulating properties by light ion irradiation: From novel functional materials to semiconductor power devices, J. Semicond. 43 063101 (2022).
[2] https://www.hzdr.de/db/Cms?pNid=1984
[3] S. Zhou, Dilute ferromagnetic semiconductors prepared by the combination of ion implantation with pulse laser melting, J. Phys. D: Appl. Phys. 48, 263001 (2015) (Topical Review)
[4] L. Rebohle, S. Prucnal, Y. Berencén, V. Begeza, S. Zhou, A snapshot review on flash lamp annealing of semiconductor materials, MRS Advances 7, 1301–1309 (2022)
[5] M. Wang et al, Breaking the doping limit in silicon by deep impurities, Phys. Rev. Appl. 11, 054039 (2019)
[6] S. Prucnal, et al., Dissolution of donor-vacancy clusters in heavily doped n-type germanium, New J. Phys. 22, 123036 (2020)
[7] M. Hoesch, Active sites of Te-hyperdoped silicon by hard x-ray photoelectron spectroscopy, Appl. Phys. Lett. 122, 252108 (2023)
[8] F. Long, Ferromagnetic interlayer coupling in CrSBr crystals irradiated by ions, arXiv:2305.18791 (2023)
[9] C. Kasper, et al, Influence of irradiation on defect spin coherence in silicon carbide, Phys. Rev. Appl. 13, 044054 (2020)
[10] Z. Shang, et al, Microwave-assisted spectroscopy of vacancy-related spin centers in hexagonal SiC, Phys. Rev. Appl. 15, 034059 (2021)

Related publications

  • Lecture (others)
    Seminar at Songshan Lake Materials Lab, 31.10.2023, Dongguan, China

Permalink: https://www.hzdr.de/publications/Publ-38310
Publ.-Id: 38310


Ion beam: an indispensable tool for chip technologies

Zhou, S.

Ion implantation followed by thermal annealing is a well-established method to dope semiconductors, e.g. Si and Ge. This approach has been maturely integrated with the integrated circuit (IC) industry production line for area- and depth-selective n/p doping as well as for lifetime engineering [1]. As a national lab in Germany, our center is running an Ion Beam Center for materials research [2]. It is open free to the international community for fundamental research based on a proposal system. With my research department “Semiconductor Materials”, we are running unique annealing methods, including millisecond flash lamp annealing and nanosecond pulsed laser melting, to repair the ion beam induced damage and to activate the dopants [3, 4]. I will show diverse research examples by using ion beam. They include pushing the doping limits in semiconductors well above the solubility limits [5-7], functionalizing 2D materials [8] and creating color centers for quantum technologies [9, 10].

[1] Ye Yuan, S. Zhou and X. Wang, Modulating properties by light ion irradiation: From novel functional materials to semiconductor power devices, J. Semicond. 43 063101 (2022).
[2] https://www.hzdr.de/db/Cms?pNid=1984
[3] S. Zhou, Dilute ferromagnetic semiconductors prepared by the combination of ion implantation with pulse laser melting, J. Phys. D: Appl. Phys. 48, 263001 (2015) (Topical Review)
[4] L. Rebohle, S. Prucnal, Y. Berencén, V. Begeza, S. Zhou, A snapshot review on flash lamp annealing of semiconductor materials, MRS Advances 7, 1301–1309 (2022)
[5] M. Wang et al, Breaking the doping limit in silicon by deep impurities, Phys. Rev. Appl. 11, 054039 (2019)
[6] S. Prucnal, et al., Dissolution of donor-vacancy clusters in heavily doped n-type germanium, New J. Phys. 22, 123036 (2020)
[7] M. Hoesch, Active sites of Te-hyperdoped silicon by hard x-ray photoelectron spectroscopy, Appl. Phys. Lett. 122, 252108 (2023)
[8] F. Long, Ferromagnetic interlayer coupling in CrSBr crystals irradiated by ions, arXiv:2305.18791 (2023)
[9] C. Kasper, et al, Influence of irradiation on defect spin coherence in silicon carbide, Phys. Rev. Appl. 13, 044054 (2020)
[10] Z. Shang, et al, Microwave-assisted spectroscopy of vacancy-related spin centers in hexagonal SiC, Phys. Rev. Appl. 15, 034059 (2021)

Related publications

  • Lecture (others)
    Seminar at Kyushu Univ. Japan, 11.09.2023, Fukuoka, Japan
  • Lecture (others) (Online presentation)
    Colloquium at Chung-Ang University, 12.09.2023, Soeul, Korea

Permalink: https://www.hzdr.de/publications/Publ-38308
Publ.-Id: 38308


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