Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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

41347 Publications

Nonperturbative Floquet engineering of the toric-code Hamiltonian and its ground state

Petiziol, F.; Wimberger, S.; Eckardt, A.; Mintert, F.

We theoretically propose a quantum simulation scheme for the toric-code Hamiltonian, the paradigmatic model of a quantum spin liquid, based on time-periodic driving. We develop a hybrid continuous-digital strategy that exploits the commutativity of different terms in the target Hamiltonian. It allows one to realize the required four-body interactions in a nonperturbative way, attaining strong coupling and the suppression of undesired processes. In addition, we design an optimal protocol for preparing the topologically ordered ground states with high fidelity. A proof-of-principle implementation of a topological device and its use to simulate the topological phase transition are also discussed. The proposed scheme finds natural implementation in architectures of superconducting qubits with tunable couplings.


Publ.-Id: 38801

Reproducibility of Arterial Spin Labeling Cerebral Blood Flow image processing: A Report of The ISMRM Open Science Initiative for Perfusion Imaging and the ASL MRI Challenge

Paschoal, A. M.; Woods, J. G.; Pinto, J.; Bron, E. E.; Petr, J.; Kennedy McConnell, F. A.; Bell, L.; Dounavi, M.-E.; van Praag, C. G.; Mutsaerts, H.-J.; Oliver Taylor, A.; Zhao, M. Y.; Brumer, I.; Siang Marcus Chan, W.; Toner, J.; Hu, J.; Zhang, L. X.; Domingos, C.; Monteiro, S. P.; Figueiredo, P.; Harms, A. G. J.; Padrela, B.; Tham, C.; Abdalle, A.; Croal, P. L.; Anazodo, U.

Purpose: Arterial Spin Labeling (ASL) is widely used in clinical research as a contrast-free MRI method for
assessment of cerebral blood flow (CBF). While the recommended guideline for ASL acquisition is
generally adopted to standardize quantification of CBF, ASL analysis still produces wide variability in CBF
estimates, limiting research and clinical interpretation of ASL results. This study explored the extent of
variability in ASL CBF quantification through the ISMRM OSIPI ASL MRI Challenge. The goal of the challenge
was to minimize sources of variability in ASL analysis by establishing best practice in ASL data processing
to make ASL analysis more reproducible and clinically meaningful.
Methods: Eight international teams analyzed the challenge data consisting of a high-resolution T1-
weighted anatomical image and ten pseudo-continuous ASL (PCASL) datasets. The datasets were
simulated using an ASL digital reference object to produce ground-truth CBF values in normal and
pathological states. The accuracy of CBF quantification from each team’s analysis was compared to
ground-truth values across all voxels and within pre-defined brain regions. Reproducibility of CBF
estimates across analysis pipelines was assessed using intra-class correlation coefficient (ICC), the limits
of agreement (LOA) and the replicability of generating similar CBF estimates from the image processing
approaches as documented.
Results: The absolute errors in CBF estimates compared to the ground-truth synthetic data ranged from
18.36 to 48.12 ml/100g/min. Realistic motion incorporated in three of the ten synthetic data produced
the largest absolute CBF error, largest variability between teams, and the least agreement (ICC and LOA)
with ground truth results. Fifty percent (4/8) of the teams’ methods were replicated, and one method
produced three times larger CBF errors (46.59 ml/100g/min) compared to submitted results.
Conclusions: The apparent variability in CBF measurements, influenced by differences in image processing
strategies, particularly in compensating for motion, demonstrates the significance for standardization of
ASL image analysis workflow. Therefore, we provide a recommendation for ASL image processing based
on top performing approaches as a step towards standardization of ASL imaging for clinical use.

Publ.-Id: 38797

Pulsating dissolution of crystalline matter: A surface-controlled process

Schabernack, J.; Fischer, C.

Rate maps quantify the variability of surface rates during the dissolution of crystalline matter. Recently, highly spatially resolved rate maps revealed the existence of rhythmic pulses of the material flux from the crystal surface. The mechanism underpinning this behavior is not yet understood but the two potential influencing factors are surface-controlled or transport-controlled conditions that may govern the resulting pulsating reaction kinetics in the system. In this study, we apply two numerical methods to identify the dominating mechanism of pulsating dissolution. First, the influence of solute transport is simulated using a reactive transport model, which yields dissolution rates and concentration distribution due to the flow field, i.e., extrinsic reactivity. Second, the influence of intrinsic surface reactivity inherent to the material is simulated using kinetic Monte Carlo (KMC) simulations, where the distribution of reactive sites over time is observed on an atomic scale. Local dissolution rates can be reproduced with the reactive transport model, but no kinetically effective periodic changes of the concentration gradients can be observed and no new dissolution pulses are generated. Control via periodic changes in extrinsic reactivity is thus ruled out as a governing mechanism. In contrast, pulsating dissolution is clearly observed in the KMC simulation, leading to the conclusion that the self-assembly of varying reactive surface building blocks causes the pulsating dissolution. The simulation results suggest that etch pits generate regions with a high number of steps of single crystal layers and, consequently, with sites of increased reactivity at periodic intervals. These steps move over the crystal surface outward from the pit center and are followed by a region with a low number of surface steps. Only when the steps reach a certain spacing to the center new steps are generated at the transition between the hollow core and the etch pit. This self-assembly is observed as a fundamental behavior of crystalline dissolution in KMC models, without any additional parametrization. It thus represents a fundamental mechanism in crystal dissolution and should be considered for an accurate atomic understanding of crystal dissolution.

Keywords: Surface reactivity; Pulsating dissolution; Kinetic Monte Carlo; Reactive transport; Calcite

Publ.-Id: 38793

The effects of fracture cross-scale surface roughness in crystalline host rocks on hydrodynamics studied by 3D modeling

Zhou, W.; Kulenkampff, J.; Heredia, D. J.; Schäfer, T.; Fischer, C.

This data provides the original inputs and COMOSL scripts for the paper 'The effects of fracture cross-scale surface roughness in crystalline host rocks on hydrodynamics studied by 3D modeling'. 


Publ.-Id: 38787

Value of [18F] FDG PET/CT parameters of the primary tumor in assessing overall survival in NSCLC patients with cN1-cN3 lymph nodes involvement

Cegla, P.; Hofheinz, F.; Czepczyński, R.; Witkowska, K.; van den Hoff, J.; Trojanowski, M.; Bos-Liedke, A.; Cholewinski, W.

Background: The aim of this retrospective study was to assess the value of 18F-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography ([18F]FDG PET/CT parameters in cN1-cN3 non-small cell lung cancer (NSCLC) patients.

Materials and methods: 59 consecutive patients (35 M, 24 F) with NSCLC who underwent pretreatment [18F]FDG PET/CT were enrolled to this study. Several primary tumor PET parameters, including the maximum and mean standardized uptake value (SUVmax and SUVmean), the metabolic active tumor volume (MTV) and the total lesion glycolysis (TLG = MTVxSUVmean), were extracted and analysed. Overall survival was defined as time from primary diagnosis to death or the last info.

Results: In the whole analysed group 44 patients underwent curative treatment, while 15, because of the severity of the disease, were classified for palliative treatment. Univariate Cox analysis of clinical and metric PET parameters revealed that MTV was a significant prognostic factor for OS (p = 0.024), while TLG and curative treatment showed a trend for significance (p < 0.1). In multivariate Cox regression (MTV and curative treatment) MTV remained a significant factor (p = 0.047).

Conclusions: Metabolic tumor volume of the primary tumor was the only independent prognostic factor for cN1–cN3 NSCLC patients.

Keywords: positron emission tomography/computed tomography; NSCLC; overall survival

  • Reports of Practical Oncology and Radiotherapy (2024)
    Online First (2024) DOI: 10.5603/rpor.99360

Publ.-Id: 38786

20 years of experience with CW-SRF operation at ELBE

Arnold, A.

ELBE is a compact, accelerator-driven photon and particle source. The variety of secondary radiation being offered extends from high-energy gamma rays to infrared and THz radiation as well as from neutrons to positrons and electrons. Since 2001 ELBE is operated as a user facility, providing more than 5500 hours of beamtime with an efficiency of more than 90% each year. The electron accelerator is based on four superconducting 9-cell TESLA cavities that are driven in CW operation to accelerate an average current of 1 mA up to beam energies of 40 MeV. In addition an upgraded 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 by this unique CW electron source every year.

The talk will summarize our experiences of operating all our SRF cavities over two decades in CW. In detail, this includes the cavity performance and attempts to improve it, as well as investigations on their limitations. Additionally, we will discuss several issues that are related to the high average RF as well as beam power and we will present appropriate measures to protect the machine. In this regard we will also introduce a resonant ring for RF component tests at CW power levels up to 100 kW. Regarding the SRF gun, the main emphasis lies in seamlessly integrating a normal-conducting photocathode into the SRF cavity, alongside addressing associated intricacies like dark current, multipacting, and contamination of the resonator.

Keywords: ELBE; CW SRF; TESLA cavity; SRF gun; photo cathode; electron source; injector

Related publications

  • Lecture (others)
    MAMI Seminar - Seminar über spezielle Probleme der Beschleunigerphysik, 08.02.2024, Mainz, Deutschland

Publ.-Id: 38759

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

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

Thermal hydraulic system models of the FFTF with the Cycle 8C core for LOFWOS Test #13, created using the ATHLET code, along with the benchmark results (point kinetics and spatial kinetics), sensitivity analyses, cross section data and DYN3D models for coupled DYN/ATHLET calculations.

Keywords: ATHLET; FFTF; Gas Expansion Module; loss of flow; point kinetics; SFR; unprotected transient; spatial kinetics; coupled calculations; DYN3D

Related publications


Publ.-Id: 38758

Solutal Marangoni force controls lateral motion of electrolytic gas bubbles

Zhang, H.; Ma, Y.; Huang, M.; Mutschke, G.; Zhang, X.

Electrochemical gas-evolving reactions have been widely used for industrial energy conversion and storage processes. Gas bubbles form frequently at the electrode surface due to a small gas solubility, thereby reducing the effective reaction area and increasing the over-potential and ohmic resistance. However, the growth and motion mechanisms for tiny gas bubbles on the electrode remains elusive. Combining molecular dynamics (MD) and fluid dynamics simulations (CFD), we show that there exists a lateral solutal Marangoni force originating from an asymmetric distribution of dissolved gas near the bubble. Both MD and CFD simulations deliver a similar magnitude of the Marangoni force of B~0.01 nN acting on the bubble. We demonstrate that this force may lead to lateral bubble oscillations and analyze the phenomenon of dynamic self-pinning of bubbles at the electrode boundary.

Publ.-Id: 38757

Data publication: Ultralong-term high-density data storage with atomic defects in SiC

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

Experimental data in OriginPro

Keywords: data storage; silicon carbide; color centers; focused ion beams; cathodoluminescence

Related publications


Publ.-Id: 38751

Surface-symmetry-driven phenomena in magnetoelectric Cr2O3

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

Antiferromagnetic (AFM) Cr$_2$O$_3$ is a unique collinear magnetoelectric material at room temperature. The bulk properties stemming from its magnetic symmetry render chromia of high interest for fundamentals and applications [1]. Features of the chromia surface remain much less explored. Here, we consider nominally compensated surfaces ($m$~and $a$~planes) of Cr$_2$O$_3$ [2]. We show that they provide a sizeable Dzyaloshinskii--Moriya interaction (DMI) determined by the surface magnetic symmetry point group and quantify it to be about 1\,mJ/m$^2$ by means of \textit{ab initio} and micromagnetic approaches. The DMI leads to the development of nonzero surface magnetization $\vec{M}$ whose sign is uniquely determined by the AFM state. The $m$ and $a$ planes of Cr$_2$O$_3$ behave as the canted ferrimagnet and canted 4-sublattice antiferromagnet, respectively. The coupling of $\vec{M}$ to the direction of the N\'{e}el vector is shown by magnetotransport measurements.

[1] P. Makushko et al., Nat. Comm. 13, 6745 (2022). [2] O.V. Pylypovskyi, S. F. Weber et al., ArXiv:2310.13438 (2023).

Keywords: Cr2O3; antiferromagnetism; single crystal; symmetry

  • Lecture (Conference)
    DPG Spring Meeting, 17.-22.03.2024, Berlin, Germany

Publ.-Id: 38738

A didactical dataset to learn supervised classification with candy

Sinichenko, V. A.; Bähr, M.; Maximilian, M.; Philip, N.; Gabriele, N.; Ihor, T.; Jessica, A.; Florian, L. C.; Martina, R.; Franziska, B.; Yashkumar, P. F.; Anna, S.; Satyam, S. G.; Dora, H.; Asma, W.; Nico, B.; Tim, Q.; Muhammad, H. K.; Benjamin, B.; Roland, N.; Laura, M.; Marius, P.; Siddhartha, J.; Tom, G.; Yaqian, Z.; Yan, A.; Lena, S.; Hamdaan, A. F.; Florens, K.; Shayan, P.; Lukas, P.; Steinbach, P.

A didactical dataset to learn supervised classification

It was obtained from university level students measuring candy that was mixed and distributed in bowls to them. The goal of this dataset creation was to expose the students to the data taking process. Further, the dataset is meant for classificatio

Keywords: Data Science; machine learning

Publ.-Id: 38732

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

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

This data repository contains the datasets used in the paper "Inverting the Kohn-Sham equations with physics-informed machine learning". 

It contains the data generation scripts, datasets for the systems used in the paper (Single Well - 1D atom, Double Well - 1D diatomic molecule) and output potentials generated by the physics-informed machine learning models (physics-informed neural networks and Fourier neural operators).

Keywords: density functional theory; machine learning

Related publications


Publ.-Id: 38725

Retrained Models and Scripts for Aluminum at 298K and 933K

Fiedler, L.; Cangi, A.

Retrained Models and Scripts for Aluminum at 298K and 933K


- Fiedler, Lenz (HZDR/CASUS)
- Cangi, Attila (HZDR/CASUS)


HZDR - Helmholtz-Zentrum Dresden-Rossendorf
CASUS - Center for Advanced Systems Understanding

Data set description

This data sets contains models, scripts and inference results for aluminum at room temperature and the melting point. Training data, hyperparameters and general methodology follow Ref. [1]. The models here are retrained versions of the ones discussed in this publication, and therefore retrained versions of the models contained in Ref. [2]. As such, data from Ref. [2] has been used. Only a subset of models contained in Ref. [1] have been retrained, namely the room temperature model, one liquid and one solid melting point model with four training snapshot each, and the final melting point hybrid model (six training snapshots per phase). Furthermore, for both the hybrid melting temperature model and the room temperature model, multiple models with different initializations were trained.

All models were trained with the MALA code [3] version 1.2.1. They show better accuracy than their original counterparts, as they were trained using the inter-snapshot shuffling algorithm first discussed for the MALA code in Ref. [4].

[1] - "Accelerating finite-temperature Kohn-Sham density functional theory with deep neural networks", Physical Review B,
[2] - "RODARE", (v1.0.0)
[3] - "MALA", Zenodo,
[4] - "Machine learning the electronic structure of matter across temperatures", Physical Review B,


- The models themselves, labeled as either Al298K or Al933K, given as one .zip file per model
    - For 933K, additionally "liquid", "solid" and "hybrid" denotes the training data set
    - For ensembles, a running index denotes the number in the ensemble
- Inference results, given as a single .zip file
    - For all models, band energy and total free energy results are given in the .csv format
        - The columns in these files correspond to "Calculated via DFT LDOS", "Calculated via ML-DFT LDOS", "Calculated via Kohn-Sham system", respectively
    - For some models, additionally the predicted electronic density and density of states on select snapshots is given
- Shuffling, training and testing scripts, given as a single .zip file
    - Scripts are ready-to-use with suitable MALA installation, however, correct data paths have to be filled in

Keywords: Data set; DFT


Publ.-Id: 38719

High-field magnetization of KEr(MoO4)2

Kutko, K.; Bernáth, B.; Khrustalyov, V.; Young, O.; Engelkamp, H.; Christianen, P. C. M.; Prodan, L.; Skourski, Y.; Pourovskii, L. V.; Khmelevskyi, S.; Kamenskyi, D.

We report a magnetization study of the rare-earth-based paramagnet KEr(MoO4)2 in a magnetic field up to 50 T. A recent observation of massive magnetostriction and rotational magnetocaloric effects in this compound triggered interest in the microscopic mechanism behind these phenomena. We combine several experimental techniques to investigate the magnetization behavior up to its saturation along three main crystallographic directions. The synergy of magnetic torque measurements and vibrating sample magnetometry allowed us to reconstruct parallel and perpendicular components of the magnetization vector, enabling us to trace its evolution up to 30 T. Our experiments reveal the magnetization saturation along all principle axes well below the value, expected from crystal electric field calculations. We argue that an externally applied magnetic field induces a distortion of the local environment of Er3+ ions and affects its crystal electric field splitting.

Publ.-Id: 38714

Templates of expected measurement uncertainties for neutron-induced capture and charged-particle production cross section observables

Lewis, A. M.; Neudecker, D.; Carlson, A. D.; Smith, D. L.; Thompson, I.; Wallner, A.; Barry, D. P.; Bernstein, L. A.; Block, R. C.; Stephen Croft, Y. D.; Drosg, M.; Haight, R. C.; Herman, M. W.; Young Lee, H.; Otuka, N.; Sjöstrand, H.; Sobes, V.

This paper provides a template of expected uncertainties and correlations for measurements
of neutron-induced capture and charged-particle production cross sections. Measurements performed in-
beam include total absorption spectroscopy, total energy detection, gamma-ray spectroscopy, and direct charged-
particle detection. Offine measurements include activation analysis and accelerator mass spectrometry. The
information needed for proper use of the datasets in resonance region and high energy region evaluations is
described, and recommended uncertainties are provided when specific values are not available for a dataset.

Publ.-Id: 38712

Templates of expected measurement uncertainties

Neudecker, D.; Lewis, A. M.; Matthews, E. F.; Vanhoy, J.; Haight, R. C.; Smith, D. L.; Talou, P.; Croft, S.; Carlson, A. D.; Pierson, B.; Wallner, A.; Al-Adili, A.; Bernstein, L.; Capote, R.; Devlin, M.; Drosg, M.; Duke, D. L.; Finch, S.; Herman, M. W.; Kelly, K. J.; Koning, A.; Lovell, A. E.; Marini, P.; Montoya, K.; Nobre, G. P. A.; Paris, M.; Pritychenko, B.; Sjöstrand, H.; Snyder, L.; Sobes, V.; Solders, A.; Taieb, J.

The covariance committee of CSEWG (Cross Section Evaluation Working Group) estab-
lished templates of expected measurement uncertainties for neutron-induced total, (n,γ), neutron-induced
charged-particle, and (n,xn) reaction cross sections as well as prompt fission neutron spectra, average
prompt and total fission neutron multiplicities, and fission yields. Templates provide a list of what uncer-
tainty sources are expected for each measurement type and observable, and suggest typical ranges of these
uncertainties and correlations based on a survey of experimental data, associated literature, and feedback
from experimenters. Information needed to faithfully include the experimental data in the nuclear-data
evaluation process is also provided. These templates could assist (a) experimenters and EXFOR compilers
in delivering more complete uncertainties and measurement information relevant for evaluations of new
experimental data, and (b) evaluators in achieving a more comprehensive uncertainty quantification for
evaluation purposes. This effort might ultimately lead to more realistic evaluated covariances for nuclear-
data applications. In this topical issue, we cover the templates coming out of this CSEWG effort–typically,
one observable per paper. This paper here prefaces this topical issue by introducing the concept and
mathematical framework of templates, discussing potential use cases, and giving an example of how they
can be applied (estimating missing experimental uncertainties of 235U(n,f) average prompt fission neutron
multiplicities), and their impact on nuclear-data evaluations.

Publ.-Id: 38711

Time-resolved nanospectroscopy on Si-doped GaAs-InGaAs core-shell nanowires

Luferau, A.; Obst, M.; Kehr, S.; Eng, L.; Winnerl, S.; Pashkin, O.; Dimakis, E.; Helm, M.

High-quality epitaxial nanowires (NWs) based on III-V semiconductors offer the possibility to fabricate ultrafast optical devices due to their direct bandgap and the high electron mobility. Contactless investigation of photoexcited carriers within single NWs is enabled by optical-pump THz-probe scanning near-filed optical microscopy (SNOM) experiment. Here we report on first THz-pump MIR-probe SNOM studies on Si-doped GaAs-InGaAs core-shell NWs utilizing THz radiation from the free-electron laser FELBE. The experiment was carried out with SNOM setup from Neaspec equipped with nanoFTIR module, where a broadband MIR source (5-15μm) serves as a probe. Upon intraband THz-pump (25μm) we observed a red shift of amplitude and phase of the NW plasma resonance, while control interband optical pumping (780nm) induced a blue shift of the resonance, and in both cases an exponential decay with a time constant of 4-5ps is seen. We attribute the blue shift to the contribution of photogenerated carriers. The red shift is assigned to the heating of the electrons in the conduction band and the subsequent increase of the effective mass in the nonparabolic Γ-valley due to high peak electric fields of THz pulses.

Keywords: s-SNOM; nanowires; nanospectroscopy

  • Contribution to proceedings
    DPG Spring Meeting of the Condensed Matter Section 2023, 26.03.2023, Dresden, Germany

Publ.-Id: 38710

THz-pump / MIR-probe nanospectroscopy on Si-doped GaAs-InGaAs core-shell nanowires

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

We report on first THz-pump / MIR-probe SNOM studies on Si-doped GaAs-InGaAs core-shell NWs utilizing THz radiation from the free-electron laser FELBE. Upon intraband THz-pump we observe a red shift of the NW plasma resonance in both amplitude and phase spectra, while a controlled interband optical pumping induces a blue shift of the resonance. In both cases, the signal exponentially decays with a time constant of 4-5 ps. We attribute the blue shift to the contribution of photogenerated charge carriers, while the red shift is assigned to the heating of electrons in the conduction band accelerated by the THz electric field of the pump pulses and the subsequent increase of their effective mass due to the nonparabolic Γ-valley dispersion.

Keywords: s-SNOM; nanowires; nanospectroscopy; FEL

  • Contribution to proceedings
    2023 48th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 17.09.-31.10.2023, Montreal, Canada


Publ.-Id: 38709

Data publication: Significant Resistance Reduction in Modulation-Doped Silicon Nanowires via Aluminum-Induced Acceptor States in SiO2

Ratschinski, I.; Nagarajan, S.; Trommer, J.; Luferau, A.; Khan, M. B.; Erbe, A.; Georgiev, Y.; Mikolajick, T.; Smith, S. C.; König, D.; Hiller, D.

Measured resistance as a function of nanowire (NW) width for different modulation doped Si NWs.

Keywords: electrical properties; modulation doping; resistance; silicon nanowires

Related publications


Publ.-Id: 38708

Significant Resistance Reduction in Modulation-Doped Silicon Nanowires via Aluminum-Induced Acceptor States in SiO2

Ratschinski, I.; Nagarajan, S.; Trommer, J.; Luferau, A.; Khan, M. B.; Erbe, A.; Georgiev, Y.; Mikolajick, T.; Smith, S. C.; König, D.; Hiller, D.

Silicon nanowires (Si NWs) like structures in the form of nanosheets are the building blocks for future transistors in the most advanced complementary metal–oxide–semiconductor technologies. However, Si NWs with few nanometers in diameter suffer from severe difficulties with respect to efficient impurity doping. These difficulties can be overcome by a novel doping concept for Si NWs comparable to the modulation doping approach known from III–V semiconductors. Modulation doping means that the parent dopant atoms are spatially separated from the volume that is to be doped by embedding them into an adjacent material with a higher bandgap. Herein, Al-doped SiO2 shells around the Si NWs are used for the experimental realization of modulation doping. In two independent experiments, a significant reduction of the electrical resistance of Si NWs by several orders of magnitude is measured, when compared to the resistance of Si NWs with undoped SiO2 shells. The results are discussed in the context of modulation doping by the surface functionalization with SiO2:Al shells.

Keywords: electrical properties; modulation doping; resistance; silicon nanowires

Related publications

Publ.-Id: 38707

Data publication: A quantitative analysis of the effect of box size in N-body simulations of the matter power spectrum

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

The dataset consists of the matter power spectra at four redshifts (z=80,50,15,0) generated by simulating Lambda-Cold Dark Matter cosmology within the cosmic screening approach as described in the associated paper. Outputs of six distinct runs are available for boxes with L= 280, 560, 1680, 4480, 5120, 5632 Mpc/h comoving sizes, each with 2 Mpc/h resolution.

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


Publ.-Id: 38704

Analyse, Planung und Umsetzung einer verteilten Informationsarchitektur für ein New Work Konzept am HZDR

Schwabe, J.

Im Zuge der zunehmenden Digitalisierung bleibt auch die Arbeitswelt von Veränderungen auf diesem Gebiet nicht unberührt.
Wechselnde Arbeitszeitmodelle und flexible sowie hybride Arbeitsplätze stellen eine Herausforderung für das klassische Flächenmanagement und die Erreichbarkeit von Mitarbeitenden dar.
Um eine veränderliche Belegung von Büroräumen für Beschäftigte zu vereinfachen, werden zunehmend verschiedene Smart Office Solutions entwickelt.
Dazu zählt auch eine flexible Informationsanzeige, um Mitarbeitende auch bei zeitlich und räumlich wechselnden Arbeitsplätzen auffinden zu können.
Am Beispiel eines am Helmholtz-Zentrum Dresden - Rossendorf (HZDR) neu entstehenden Bürogebäudes wird im Rahmen dieser Arbeit ein verteiltes Informationssytem konzipiert und ein Prototyp dessen mit den Basis-Funktionalitäten implementiert.
Dabei kommuniziert ein digitales, kabelloses Türschild in einem drahtlosen Netzwerk mit einem zentralen Server, welcher Informationen aus bestehenden Datenbanken zu aktuellen Raumbelegungen ausliest.
Diese Informationen werden automatisiert auf dem ePaper-Display des Türschildes angezeigt.
Im Vordergrund steht dabei ein möglichst geringer Energiebedarf der über eine mobile Spannungsquelle mit Strom zu versorgenden Türschilder.

Keywords: Data Science; Data Management; Electronic Door Sign; E-Paper; New Work; Smart Office; Python; Arduino; ESP8266

Related publications

  • Bachelor thesis
    Berufsakademie Sachsen, Staatliche Studienakademie Dresden, 2023
    Mentor: Dr.-Ing. Oliver Knodel, Dr. rer. nat. Dietbert Gütter

Publ.-Id: 38703

Evaluating the quality of pure mineral extraction during luminescence sample preparation

Melo Girón, A. M.; Fuchs, M.; Gloaguen, R.; Dornich, K.; Heitmann, J.

Through the last 50 years, Optically Stimulated Luminescence (OSL) dating has been applied to get absolute age estimates for the last exposure of minerals like quartz or feldspar to light or heat. The method provides manifold applications for unraveling the geochronological scale of surface processes and related sediment archives. Over time, technology and techniques improved creating new ways to get a more accurate age. However, ensuring the quality of dating results commenceswith sample preparation and accurate extraction of the dosimeter (quartz or feldspar). Standard separation procedures for quartz-based OSL dating involve a series of steps to enrich the quartz. Due different wettability of feldspar and quartz is possible
to separate them through froth flotation. Our goal is to determine the quality of quartz separation of one poly-mineral sample of fluvial sediments from Pamir applying feldspar flotation. This froth-type method showed in past experiments quartz concentrations of 95-100 %. Using X-ray diffraction analysis, we trace the chemical composition of each step of the process to illustrate the advantage of this froth method in getting high-purity quartz extracts.

Keywords: Luminescence

Publ.-Id: 38701

Luminescence dating of active faults in New Zealand: first insights from pIRIR225

Melo Girón, A. M.; Tsukamoto, S.; Fuchs, M.; Tanner, D.; Brandes, C.; Kroner, U.; Gloaguen, R.

We aim to test the potential of luminescence dating to determine the relative activity of three active faults in New Zealand. To this end, we collected four dark-gray, fine to very fine grain-size samples classified as cataclasite and gouge from outcrops situated along the fault traces of the Alpine Fault, Hope Fault, and Hundalee Fault. Through sample processing, we obtained polymineral fine grains, ranging from 4 to 11 µm, to conduct post-infrared infrared stimulated luminescence (pIRIR225) dating. In this work, we show the first insights into the Luminescence properties, in the first attend to record ages in active faults in New Zealand using direct dating on gouge and cataclasites.

Keywords: Earthquakes

Publ.-Id: 38700

Data publication: Microstructure-informed prediction of hardening in ion-irradiated reactor pressure vessel steels

Lai, L.; Brandenburg, J.-E.; Chekhonin, P.; Duplessi, A.; Cuvilly, F.; Etienne, A.; Radiguet, B.; Rafaja, D.; Bergner, F.

Mainly the original data for model establishment.

Keywords: reactor pressure vessel steels; ion irradiation; microstructure characterization; transmission electron microscopy; atom probe tomography; nanoindentation; hardening

Related publications


Publ.-Id: 38698

Microstructure-informed prediction of hardening in ion-irradiated reactor pressure vessel steels

Lai, L.; Brandenburg, J.-E.; Chekhonin, P.; Duplessi, A.; Cuvilly, F.; Etienne, A.; Radiguet, B.; Rafaja, D.; Bergner, F.

Ion irradiation combined with nanoindentation is a promising tool to study irradiation-induced hardening of nuclear materials including reactor pressure vessel (RPV) steels. For RPV steels, the major sources of hardening are nm-sized irradiation-induced dislocation loops and solute atom clusters, both representing barriers for dislocation glide. The dispersed barrier hardening (DBH) model provides a link between the irradiation-induced nanofeatures and hardening. However, a number of details of the DBH model still require consideration. These include the role of the unirradiated microstructure, the proper treatment of the indentation size effect (ISE), and the appropriate superposition rule of individual hardening contributions. In the present study, two well characterized RPV steels, each ion-irradiated up to two different levels of displacement damage, were investigated. Dislocation loops and solute atom clusters were characterized by transmission electron microscopy and atom probe tomography, respectively. Nanoindentation with a Berkovich indenter was used to measure indentation hardness as a function of the contact depth. In the present paper, the measured hardening profiles are compared with predictions based on different DBH models. Conclusions about the appropriate superposition rule and the consideration of the ISE (in terms of geometrically necessary dislocations) are drawn.

Keywords: reactor pressure vessel steels; ion irradiation; microstructure characterization; transmission electron microscopy; atom probe tomography; nanoindentation; hardening

Related publications

Publ.-Id: 38696

In operando visualization of mass transfer in a sodium-zinc molten salt battery with liquid electrolyte

Sarma, M.; Nash, W.; Weber, N.; Weier, T.

To bring the novel Na-Zn molten salt battery to market, many unresolved issues – such as self-discharge, migration of Na away from the current collector, and electrolyte “creeping” – must be resolved. Within the framework of the Horizon 2020 project SOLSTICE, a working battery prototype must be delivered. To support this objective, a small-scale experimental cell that can be used for fundamental research has been built. The cell has been designed to permit in situ radiographic imaging of its interior. The aim is to charge and discharge this cell in a neutron beamline and an X-ray source, to observe mass transfer of electroactive species and any flow that occurs during cycling. Of most interest are how these phenomena depend on the geometry and chemical composition of the different cell components, e.g. the positive and negative current collectors.
With a completely liquid interior, all the cell’s components must retain their performance characteristics at its 600oC operating temperature. Besides thermal stress, the cell’s walls and current collectors must resist corrosion by liquid Zn, Na, and the molten salt electrolyte (as well as their vapors). Maintenance of this high internal temperature also requires sufficient thermal insulation, and – in an isolated test cell – an external heating system, and neither of these should interfere with the imaging techniques.
Preliminary attempts to cycle the cell for an extended period of time (>4 weeks) have been successful. Pilot imaging tests using neutron and X-ray radiography have confirmed that the different layers (the electrodes and electrolyte) can be distinguished from one another, and spatial variations in the chemical composition of the electrolyte can be resolved. However, corrosion remains a limitation for long-term structural stability, so optimization of the cell’s components is ongoing. Long-term cycling data and X-ray/neutron images will be presented in this talk, and their implications for improvements to the cell design will be discussed.

  • Lecture (Conference)
    4th International Sodium Battery Symposium (SBS4), 04.09.2023, Dresden, Deutschland

Publ.-Id: 38694

Mass transport and solutal convection in a sodium-zinc molten salt battery with liquid electrolyte: comparison of modelling and experiments

Sarma, M.; Duczek, C.; Nash, W.; Weber, N.; Weier, T.

Within the Horizon 2020 project SOLSTICE, a molten salt battery has been developed. The battery employs sodium and zinc as anode and cathode respectively and operates at around 600 oC with a completely liquid interior. The primary advantage of this design is its low materials’ cost. However, multiple challenges must be overcome if it is to become commercially viable. These include corrosion of metallic components by the molten salt electrolyte, and self-discharge promoted by transport of cathode materials (Zn2+ ions) to the anode. Efforts to suppress the latter especially benefit from modelling, as the rate of self-discharge is primarily determined by mass transport processes in the electrolyte. Such models require experimental validation, thus, a small-scale experimental cell has been constructed for this purpose. It has been designed specifically for operation during analysis by radiographic methods (neutron beam and X-ray imaging). The distribution of the active materials can be observed at different stages of the charging-discharging cycle. This presentation will provide an overview of current modelling activities at HZDR related to the sodium-zinc battery, together with first (preliminary) experimental results and the most recent progress towards designing a “transparent” cell.

  • Lecture (Conference)
    9th International Scientific Colloquium "Modelling for Materials Processing" 2023, 18.09.2023, Riga, Latvija

Publ.-Id: 38693

Magnetocaloric effect in the Laves phases RCo2 (R = Er, Ho, Dy, and Tb) in high magnetic fields

Bykov, E.; Karpenkov, A.; Liu, W.; Straßheim, M.; Niehoff, T.; Skokov, K.; Scheibel, F.; Gutfleisch, O.; Salazar Mejia, C.; Wosnitza, J.; Gottschall, T.

The heavy rare-earth-based Laves phases are well-studied intermetallic materials that stand out for their remarkably high magnetocaloric effects, particularly at cryogenic temperatures. In this study, we present the findings of our comprehensive investigation of cobalt Laves phases RCo2 with R standing for erbium, holmium, dysprosium, and terbium. This includes the determination of the magnetocaloric effect by indirect methods using calorimetric and magnetization data. Furthermore, for the first time in these materials, we directly measured the adiabatic temperature change at high magnetic fields up to 20 T. The largest ΔTad value of 17 K, we obtained for ErCo2. Because the order of the transition significantly impacts the efficiency of thermodynamic cycles, we have also focused on determining the transition order in these materials. This was done through the application of established methods and a recently proposed quantitative criterion including the value of the local exponent n. Further, we compare our results with other materials using a straightforward material-based figure of merit - the temperature-averaged entropy change (TEC). Our results demonstrate the great potential of these materials for applications such as for magnetic hydrogen liquefaction.

Publ.-Id: 38692

Data publication: How to verify the precision of density-functional-theory implementations via reproducible and universal workflows

Bosoni, E.; Beal, L.; Bercx, M.; Blaha, P.; Blugel, S.; Broder, J.; Callsen, M.; Cottenier, S.; Degomme, A.; Dikan, V.; Eimre, K.; Flage-Larsen, E.; Fornari, M.; Garcia, A.; Genovese, L.; Giantomassi, M.; Huber, S. P.; Janssen, H.; Kastlunger, G.; Krack, M.; Kresse, G.; Kühne, T. D.-S.; Lejaeghere, K.; Madsen, G. K. H.; Marsman, M.; Marzari, N.; Michalicek, G.; Mirhosseini, H.; Muller, T. M. A.; Petretto, G.; Pickard, C. J.; Ponce, S.; Rignanese, G.-M.; Rubel, O.; Ruh, T.; Sluydts, M.; Vanpoucke, D. E. P.; Vijay, S.; Wolloch, M.; Wortmann, D.; Yakutovich, A. V.; Yu, J.; Zadoks, A.; Zhu, B.; Pizzi, G.

In this Expert Recommendation, we list a set of guiding principles to perform new verification studies of DFT calculations, and we illustrate examples of verification by using a curated reference set of highly converged results for the EOS of 960 crystals, with two independent state-of-the-art all-electron (AE) DFT codes (FLEUR and WIEN2k).

Keywords: Density-functional theory; Verification; pseudopotential codes

Related publications

  • Reseach data in external data repository
    Publication year 2023
    License: CC-BY-4.0
    Hosted on materials cloud: Link to location

Publ.-Id: 38691

Laterally resolved polymorph conversion in Ga2O3 using FIBs

Bektas, U.; Klingner, N.; Hübner, R.; Chekhonin, P.; Liedke, M. O.; Hlawacek, G.

Laterally resolved polymoprh conversion in Galliumoxide
using Focused Ion Beams

Keywords: FIB

Related publications

  • Lecture (Conference) (Online presentation)
    Defect Engineering in SiC and Other Wide Bandgap Semiconductor, 22.-24.10.2023, Erlangen, Shenzen, Deutschaldn, China

Publ.-Id: 38690

Materials Science with Fibs across Applications and Fluencies at the HZDR Ion Beam Center.

Hlawacek, G.

Materials Science with Fibs across Applications and Fluencies at the HZDR Ion Beam Center.

Keywords: FIB

Related publications

  • Invited lecture (Conferences)
    CINT User meeting, 19.-20.09.2023, Santa Fe, USA

Publ.-Id: 38689

Applications of unconventional focused ion beams in quantum and semiconductor technology

Hlawacek, G.

Applications of unconventional focused ion beams in
quantum and semiconductor technology

Keywords: FIB

Related publications

  • Lecture (others)
    Institutsseminar, 10.05.2023, Leipzig, Deutschland

Publ.-Id: 38688

Application of gas field ion source and liquid metal alloy ion source based focused ion beams

Hlawacek, G.

I will present recent results obtained in our group using gas field ion sources (GFIS)1 and liquid metal alloy ion
source (LMAIS)2 based focused ion beams (FIB). I will briefly explain the source technology and our efforts
in developing new and unconventional ion sources for their application in FIB instruments. A few selected
examples will include the LMAIS based fabrication of single photon emitters (SPE) which are fundamental
building blocks for future quantum technology applications. I will present a method to fabricate at will placed
single or few SPEs emitting in the telecom O-band in Silicon3 . The successful integration of these telecom
quantum emitters into photonic structures such as micro-resonators, nanopillars and photonic crystals with
sub-micrometer precision paves the way toward a monolithic, all-silicon-based semiconductor-superconductor
quantum circuit for which this work lays the foundations. To achieve our goal we employ home built AuSi
and a unique CeC LMAIS both operated in an Orsay Physics CANION M31Z+ FIB. Silicon-on-insulator
substrates from different fabrication methods have been irradiated with a spot pattern. The achieved lateral
SPE placement accuracy is below 100 nm in both cases and the success rate of SPE formation is more than
50%. In addition I will present recent results obtained on the helium ion microscope using FIB and He ion
extracted from a GFIS source. These examples will include the epitaxial over growth of Sn spheres during He
ion beam irradiation. This more fundamental experiment show cases the importance of the ion beam driven
generation of interstitials and their diffusion during the ion beam irradiation4 . Finally, I’d like to demonstrate
how GFIS based HIM can be used to generate electrically controlled magnetic landscapes in spin orbit torque
(SOT) materials. Here, we use in-situ controlled irradiation to identify the best irradiation conditions for the
preparation of µm sized areas which will switch magnetization direction at different SOT currents5 .
Financial support by the COST Action CA19140 is acknowledged.

Keywords: FIB

Related publications

  • Lecture (others)
    Department Seminar, 13.04.2023, Pasadena, USA

Publ.-Id: 38687

High fluence He irradiation of materials using Helium Ion Microscopy

Hlawacek, G.; Klingner, N.; Lohmann, S.; Hübner, R.; Gandy, A.

I will present some recent results on the high fluence irradiation of metals using gas field ion source (GFIS) based
helium ion microscope (HIM)1 .
High entropy alloys (HEAs) are a relatively new class of metal alloys composed of several principal elements, usually
at (near) equiatomic ratios. Here, our goal is to understand how such a multicomponent alloy behaves under irradiation.
The FeCoCrNiV HEA exhibits both a face-centred cubic (fcc) and a body-centred tetragonal (bct) phase, thus allowing
us to specifically study the influence of crystalline structure at very similar chemical composition. We irradiated both
phases with a focussed He beam provided by a HIM at temperatures between room temperature and 500 ∘ C. The
irradiation fluence was varied between 6 × 1017 ions cm−2 to 1 × 1020 ions cm−2 . High-resolution images of the irradiated
areas were taken with the same HIM. Selected irradiated areas were additionally studied by transmission electron
microscopy (TEM) in combination with energy dispersive X-ray spectroscopy (EDXS). Under irradiation, pores start
to be generated in the material with pore sizes differing significantly between the two phases. At higher fluences and
above a critical temperature, a tendril structure forms in both phases. We found that the critical temperature depends
on the phase and is lower for fcc. TEM images reveal that the tendrils span the whole depth of the irradiated area, and
are accompanied by bubbles of various sizes. Scanning TEM-based EDXS of these structures indicates a He-induced
change in composition.
In the second part I want to present an intriguing observation shedding light on the fundamental processes related
to interstitial diffusion during irradiation. I will show how epitaxial growth of tin extrusions on tin-oxide-covered tin
spheres can be induced and simultaneously observed by implanting helium using a HIM2 . Calculations of collision
cascades based on the binary collision approximation (BCA) and 3D-lattice-kinetic Monte Carlo (3D-lkMC) simulations
show that the implanted helium will occupy vacancy sites, leading to a tin interstitial excess. Sputtering and phase
separation of the tin oxide skin, which is impermeable for tin atoms, create holes and will allow the epitaxial overgrowth
to start. Simultaneously, helium accumulates inside the irradiated spheres. Fitting the simulations to the experimentally
observed morphology allows us to estimate the tin to tin-oxide interface energy to be 1.98 J m−2 .
Both approach have in common that they employ spatially resolved irradiation and in-situ observation of defect
diffusion-driven effects to improve the understanding of the formation mechanism of ion induced structures.
Financial support by the COST Action CA19140 is acknowledged.

Keywords: FIB

Related publications

  • Lecture (others)
    Department Seminar, 11.04.2023, Berkeley, USA

Publ.-Id: 38686

Gallium Oxide Fabrication with Ion Beams

Hlawacek, G.; Klingner, N.; Bektas, U.; Chekhonin, P.; Erb, D.; Kuznetsov, A.; Azarov, A.; García Fernández, J.; Zhao, J.; Djurabekova, F.

Gallium oxide is a novel ultra-wide band gap material, and the rationale for the current research project
is that its thin film fabrication technology is immature. In particular, the metastability conditions are
difficult to control during sequential deposition of different polymorphs with existing techniques. However, the
polymorphism may turn into a significant advantage if one can gain control over the polymorph multilayer
and nanostructure design. Our objective is to develop a method for the controllable solid state polymorph
conversion of gallium oxide assisted by ion irradiation. This fabrication method may pave the way for several
potential applications (e.g. in power electronics, optoelectronics, thermoelectricity batteries) and we will test
the corresponding functionalities during the project. Thus, we envisage multiple positive impacts and potential
benefits across a wide range of stakeholders.
I will introduce the aims and objectives of project paying specific attention to the planned methodology to
gain spatial control over the polymorph conversion. In the second half I will present the first results obtained
in the last 5 month. This includes broad beam irradiation which confirms the successful polymorph conversion
independent of primary ion species and the related exceptional radiation tolerance of the formed g-Ga2 O3 layer.
Further I will report the first spatially resolved focused ion beam (FIB) induced b- to g-Ga2 O3 polymorph
conversion. For this result different FIBs—available at the Ion Beam Center—have been used. These are in
particular the Helium Ion Microscope (HIM) using Neon ions, a conventional Gallium liquid metal ion source
(LMIS) based FIB as well as a liquid metal alloy ion source (LMAIS) FIB using Co ions. The confirmation of
the latter result also required the test and optimization of an electron backscatter diffraction (EBSD) based
analysis method.
I will end with an outlook on experiments foreseen for the rest of the project duration.
Support by the State of Saxony via Project 100629936 GoFIB—Gallium Oxide Fabrication with Ion Beams
and the COST Action 19140 FIT4NANO is acknowledged.

Keywords: FIB

Related publications

  • Lecture (others)
    Infineon InnoTalk, 05.04.2023, Dresden, Deutschland

Publ.-Id: 38685

PCB-Vision: A Multiscene RGB-Hyperspectral Benchmark Dataset of Printed Circuit Boards

Arbash, E.; Fuchs, M.; Rasti, B.; Lorenz, S.; Ghamisi, P.; Gloaguen, R.

PCB-Vision Dataset


The PCB-Vision dataset is a multiscene RGB-Hyperspectral benchmark dataset comprising 53 Printed Circuit Boards (PCBs). The RGB images are collected using a Teledyne Dalsa C4020 camera on a conveyor belt, while hyperspectral images (HSI) are acquired with a Specim FX10 spectrometer. The HSI data contains 224 bands in the VNIR range [400 - 1000]nm.

Data Format

  • RGB Images: .png files
  • PCB Masks: .jpg files
  • HSI Data: Each hyperspectral data cube is accompanied by a data file and a .hdr file.

Folder Organization

  • PCBVision
    • HSI/
      • 53 subfolders (one for each PCB)
      • 'General_masks' folder for 'General' segmentation ground truth
      • 'Monoseg_masks' folder for 'Monoseg' segmentation ground truth
      • 'PCB_Masks' folder for masks of the 53 PCBs in the hyperspectral cube
    • RGB/
      • 53 .jpg images
      • 'General' folder for RGB images 'General' segmentation ground truth
      • 'Monoseg_masks' folder for RGB images 'Monoseg' segmentation ground truth

Data Classes in Masks

  • Masks (both 'General' and 'Monoseg') contain 1 to 4 segmentation classes:
    • 0: "Others"
    • 1: "IC"
    • 2: "Capacitors"
    • 3: "Connectors"

Code Repository

To facilitate reading and working with the data, Python codes are available on the GitHub repository:


If you use this dataset, please cite the following article:


Arbash, Elias, Fuchs, Margret, Rasti, Behnood, Lorenz, Sandra, Ghamisi, Pedram, & Gloaguen, Richard. (2024). PCB-Vision: A Multiscene RGB-Hyperspectral Benchmark Dataset of Printed Circuit Boards (Version 1) [Data set]. Rodare.


@article{arbash2024pcb, title={PCB-Vision: A Multiscene RGB-Hyperspectral Benchmark Dataset of Printed Circuit Boards}, author={Arbash, Elias and Fuchs, Margret and Rasti, Behnood and Lorenz, Sandra and Ghamisi, Pedram and Gloaguen, Richard}, journal={arXiv preprint arXiv:2401.06528}, year={2024} }


For further information or inquiries, please visit our website:

Contact Email:

Keywords: circular economy; automated data processing; optical sensors; recycling; e-waste; printed circuit board; hyperspectral; dataset; RGB; conveyor belt; sensors; machine learning; deep learning; PCBVision; open-source data; digitalization

Related publications


Publ.-Id: 38684

Spatially Resolved Polymorph Conversion in Ga2O3

Bektas, U.; Chekhonin, P.; Heller, R.; Hübner, R.; Liedke, M. O.; Klingner, N.; Hlawacek, G.

Monoclinic galliumoxide (β-Ga2O3) is a promising wideband gap
semiconductor with a bandgap of 4.7 eV and a high breakdown voltage.
However, the existence of several metastable polymorphs and the
immature fabrication technology limits its applications. The research is
based on the recent observation that β-Ga2O3 can reliable be converted
into γ-Ga2O3 using high energy ion beams [1,2]. It could also be shown that
the resulting γ-Ga2O3 layer exhibits an exceptional tolerance towards high
fluence ion beam irradiation [3].
Here, we use focused ion beam (FIB) induced processing to convert β-Ga2O3
into γ-Ga2O3 in a spatially controlled way. We employ focused Ne ions from
a helium ion microscope (HIM) and liquid metal alloy ion sources (LMAIS)
based FIB with Co, Si, and In to induce the polymorph conversion. Electron
backscatter diffraction (EBSD), transmission electron microscopy (TEM) and
atomic force microscopy (AFM) are used to confirm, in a spatially resolved
way, the successful polymorph conversion. From the obtained EBSD data
the orientation relationship between the irradiated and unirradiated
material is resolved. Broadbeam irradiated reference samples have been
used to corroborate these results with channeling Rutherford
backscattering spectrometry (c-RBS), X-ray diffraction (XRD) and Doppler
broadening variable energy positron annihilation spectroscopy (DB-VEPAS)
results. The obtained crystal structure and defect distribution data supports
the model suggested for the conversion mechanism [3].
This research is supported by the tax funds on the basis of the budget
passed by the Saxonian state parliament in Germany and the COST Action
[1] A. Azarov, C. Bazioti, Disorder-Induced Ordering in Gallium Oxide
Polymorphs, Phys. Rev. Lett. 128 (2022), 015704.
[2] J. Garcia-Fernandez, S.B. KJeldby, Formation of γ-Ga2O3 by ion
implantation: Polymorphic phase transformation of β- Ga2O3, Appl. Phys.
Lett. 121 (2022), 191601.
[3] A. Azarov, J. G. Fernández, J. Zhao, F. Djurabekova, H. He, R. He, Ø. Prytz,
L. Vines, U. Bektas, P. Chekhonin, N. Klingner, G. Hlawacek, A. Kuznetsov,
Universal radiation tolerant semiconductor (2023),

Keywords: FIB

Related publications

  • Lecture (Conference)
    AVS 69, 05.-10.11.2023, Portland, OR, USA

Publ.-Id: 38683

Influence of crystal structure on helium-induced tendril formation in an FeCoCrNiV high-entropy alloy

Lohmann, S.; Goodall, R.; Hlawacek, G.; Hübner, R.; Ma, L.; Gandy, A. S.

High-entropy alloys (HEAs) are a relatively new class of metal alloys
composed of several principal elements, usually at (near) equiatomic
ratios. Our goal is to understand how such a multicomponent alloy
behaves under irradiation. The FeCoCrNiV HEA exhibits both a face-
centred cubic (fcc) and a body-centred tetragonal (bct) phase, thus
allowing us to specifically study the influence of crystalline structure
at very similar chemical composition. We irradiated both phases with
a focussed He beam provided by a helium ion microscope (HIM) at
temperatures between room temperature and 500∘ C. The irradiation
fluence was varied between 6 × 1017 ions/cm2 and 1 × 1020 ions/cm2 .
High-resolution images of the irradiated areas were taken with the same
HIM. Selected irradiated areas were additionally studied by TEM in
combination with EDXS. Under irradiation, pores start to be generated
in the material with pore sizes differing significantly between the two
phases. At higher fluences and above a critical temperature, a tendril
structure forms in both phases. We found that the critical tempera-
ture depends on the phase and is lower for fcc. TEM images reveal
that the tendrils span the whole depth of the irradiated area, and are
accompanied by bubbles of various sizes. Scanning TEM-based EDXS
of these structures indicates a He-induced change in composition.

Keywords: FIB

Related publications

  • Lecture (Conference)
    DPG, 20.-24.03.2023, Dresden, Deutschland

Publ.-Id: 38682

Influence of Crystal Structure on Helium-induced Nano-tendril Formation in a Multiphase, Multicomponent Alloy

Gandy, A.; Lohmann, S.; Hlawacek, G.; Hübner, R.; Ma, L.; Goodall, R.

Plasma-facing materials (PFMs) for magnetic fusion will experience a unique set of challenges, including plasma-surface interactions. In tungsten, helium ions diffuse through the surface resulting in the formation of nano-tendrils which may contaminate the fusion plasma. Multicomponent alloys are being considered as alternative PFMs though little is known about how they will behave in a plasma environment. Using a focused helium beam provided by a helium ion microscope (HIM), we irradiated equiatomic FeCoCrNiV, which comprises FCC and BCT crystal structures with similar compositions, enabling us to determine the influence of crystal structure on the formation of nano-tendrils. Irradiations were performed up to 500°C, and fluences between 6x1017 and 1x1020 He ions/cm2. Here, we present HIM images from the irradiated regions, and cross-sectional TEM/EDX images on selected samples. The data reveals a critical temperature for tendril formation dependant on crystal structure, helium bubbles, and helium-induced changes in composition.

Keywords: FIB

Related publications

  • Lecture (Conference)
    TMS 2023 - 152nd Annual Meeting & Exhibition, 19.-23.03.2023, San Diego, USA

Publ.-Id: 38680

Creep strength boosted by a high-density of stable nanoprecipitates in high-chromium steels

Vivas, J.; De-Castro, D.; Poplawsky, J. D.; Altstadt, E.; Houska, M.; Urones-Garrote, E.; San Martín, D.; Caballero, F. G.; Serrano, M.; Capdevila, C.

there is a need worldwide to develop materials for advanced power plants with steam temperatures of 700°c and above that will achieve long-term creep-rupture strength and low cO2 emissions. the creep resistance of actual 9-12cr steels is not enough to fulfil the engineering requirements above 600°c. in this paper, the authors report their advances in the improvement of creep properties of this type of steels by the microstructural optimization through nano-precipitation using two methodologies. 1) Applying a high temperature austenitization cycle followed by an ausforming step (thermomechanical treatment, tMt ) to G91 steel, to increase the martensite dislocation density and, thus, the number density of MX precipitates (M = v,Nb; X = c,N) but at the expense of deteriorating the ductility. 2) compositional adjustments, guided by computational thermodynamics, combined with a conventional heat treatment (no tMt ), to design novel steels with a good ductility while still possessing a high number density of MX precipitates, similar to the one obtained after the tMt in G91. the microstructures have been characterized by optical, scanning and transmission electron microscopy, eBSD and atom probe tomog- raphy. the creep behaviour at 700°c has been eval- uated under a load of 200 N using small punch creep tests.

Keywords: creep resistant steels; thermomechanical treatment; creep fracture behaviour; microstructural degradation; small punch creep tests; ausforming

Publ.-Id: 38678

Nanoparticle depressants - The effect of colloidal silica in the froth flotation of calcium minerals

Ben Said, B.; Pereira, L.; Rudolph, M.

Colloidal silica is investigated as a potential selective nanoparticle depressant in the flotation process of calcium minerals. The micro particle separation of calcium minerals by selective froth flotation is a challenging task. The difficulty arises from the similar surface properties of the minerals and thus similar responses to different known families of flotation collectors (selectively adsorbing surfactants). The effect of colloidal silica and its interactions with the reagent system were investigated by varying its modification and specific surface area/particle size. Microflotation of scheelite (calcium tungstate), fluorite (calcium fluoride), calcite (calcium carbonate) and apatite (calcium fluorophosphate) was used to investigate whether colloidal silica has an effect on the minerals. Initial results show that colloidal silica prevents calcite from floating, while scheelite, fluorite and apatite are not affected by the presence of the reagent, regardless of the dosage. Moreover, batch flotation tests have shown significant differences between the three modifications (Sodium stabilized colloidal silica, sodium stabilized modified with aluminate and sodium stabilized modified with silane) in terms of the significant effect on the selectivity. Fundamental investigations have been carried out to figure out how the different modifications perform and at which phase of the flotation process. The upscaling of the technology was then investigated on a pilot and industrial scale.

Keywords: Froth Flotation; Nanoparticles; Adsorption; Bubble Attachment; Particle Interactions

  • Poster
    Flotation23, 05.-09.11.2023, Cape Town, South Africa

Publ.-Id: 38675

Data publication: MRF timing system characterization and 1-wire sensor calibration using a climate chamber

Zenker, K.; Kuntzsch, M.

This data was taken at DSEY (04-08.12.2023) using a climate chamber.

Multiple temperature and humidity sensors were put into the climate chamber.

Due to problems with the ChimeraTK server not all data was collected by a single ChimeraTK server,

but the sensors were grouped and read by different 1-wire servers (`1-wire_1`, `1-wire_2`, `1-wire_3`, `1-wire_4`, `1-wire_5`). Each sensor identification is listed in the owfs.xlmap file. First sensor in owfs.xlmap corresponds e.g. to DS18B20/0. Data is available as HDF5 and ROOT file.

In addition the MRF timing system was running. Two EVRs (EVR2, EVR3) were connected via long fibers (100m) to the EVM. The fibers routed through the climate chamber, such that most of the fiber was inside the chamber. A Rhode&Schwartz oscilloscope was used to measure the delay of the timing output signals with respect to a third EVR (EVR1), that was connected via a short cable outside the climate chamber. That data is included in timing-data.root, which includes:

  • Delay of EVR2 with respect to EVR1 -> Delay_C1C2
  • Delay of EVR3 with respect to EVR1 -> Delay_C1C3
  • Delay compensation (actual, correction) for each EVR

The intended measurement, was to use active delay compensation for EVR2 and deactivated delay compensation for EVR3. However, the measurement was spoiled by periodic delay shifts in case of EVR2. On 07.12. 10:20 the delay compensation was also activated for EVR3.

For technical reasons not all timing related data is included in rs-data.root. The delay compensation data (actual, correction) should be taken from the aggregated raw data. It includes basically all data (temperature, humidity, oscilloscope data), but in the beginning the actual delay measurement was missing (which should be taken from timing-data.root).

Selected data periods are listed in the file data.ods.

Some analysis results are already included here for convenience:

  • Plots includes:
    • Temperature calibration
    • Humidity calibration
    • Delay measurements
  • Calibration.root includes calibration constants for humidity/temperature calibration and graphs/plots

Keywords: ELBE; Timing System

Related publications


Publ.-Id: 38668

How to verify the precision of density-functional-theory implementations via reproducible and universal workflows

Bosoni, E.; Beal, L.; Bercx, M.; Blaha, P.; Blugel, S.; Broder, J.; Callsen, M.; Cottenier, S.; Degomme, A.; Dikan, V.; Eimre, K.; Flage-Larsen, E.; Fornari, M.; Garcia, A.; Genovese, L.; Giantomassi, M.; Huber, S. P.; Janssen, H.; Kastlunger, G.; Krack, M.; Kresse, G.; Kühne, T. D.-S.; Lejaeghere, K.; Madsen, G. K. H.; Marsman, M.; Marzari, N.; Michalicek, G.; Mirhosseini, H.; Muller, T. M. A.; Petretto, G.; Pickard, C. J.; Ponce, S.; Rignanese, G.-M.; Rubel, O.; Ruh, T.; Sluydts, M.; Vanpoucke, D. E. P.; Vijay, S.; Wolloch, M.; Wortmann, D.; Yakutovich, A. V.; Yu, J.; Zadoks, A.; Zhu, B.; Pizzi, G.

Density-functional theory methods and codes adopting periodic boundary conditions are extensively used in condensed matter physics and materials science research. In 2016, their precision (how well properties computed with different codes agree among each other) was systematically assessed on elemental crystals: a first crucial step to evaluate the reliability of such computations. In this Expert Recommendation, we discuss recommendations for verification studies aiming at further testing precision and transferability of density-functional-theory computational approaches and codes. We illustrate such recommendations using a greatly expanded protocol covering the whole periodic table from Z = 1 to 96 and characterizing 10 prototypical cubic compounds for each element: four unaries and six oxides, spanning a wide range of coordination numbers and oxidation states. The primary outcome is a reference dataset of 960 equations of state cross-checked between two all-electron codes, then used to verify and improve nine pseudopotential-based approaches. Finally, we discuss the extent to which the current results for total energies can be reused for different goals.

Keywords: Density-functional theory; Verification; pseudopotential codes

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Publ.-Id: 38667

Triply Bonded Pancake π-Dimers Stabilized by Tetravalent Actinides

Barluzzi, L.; Ogilvie, S. P.; Dalton, A. B.; Kaden, P.; Gericke, R.; Mansikkamäki, A.; Giblin, S. R.; Layfield, R. A.

Aromatic π-stacking is a weakly attractive, non-covalent interaction often found in biological macromolecules and synthetic supramolecular chemistry. The weak non-directional nature of π-stacking can present challenges in the design of materials owing to their weak, non-directional nature. However, when aromatic π-systems contain an unpaired electron, stronger attraction involving face-to-face π-orbital overlap is possible, resulting in covalent so-called ‘pancake’ bonds. Two-electron, multicentre single pancake bonds are well-known whereas four-electron double pancake bonds are rare. Higherorder
pancake bonds have been predicted, but experimental systems are unknown. Here, we show that six-electron triple pancake bonds can be synthesized by threefold reduction of hexaazatrinaphthylene (HAN) and subsequent stacking of the [HAN]³‾ tri-radicals. Our analysis reveals a multicentre covalent triple pancake bond consisting of a π-orbital and two equivalent π-orbitals. An electrostatic stabilizing role is established for tetravalent thorium and uranium ions in these systems. We also show that the electronic absorption spectrum of the triple pancake bonds closely matches computational predictions, providing experimental verification of these unique interactions. The discovery of conductivity in thin films of the triply bonded π-dimers presents new opportunities for the discovery of single-component molecular conductors and other spinbased molecular materials.

Keywords: actinides; triply bonded pancake; stabilization; magnetism; EPR; quantum chemistry

  • Open Access Logo Journal of the American Chemical Society 146(2024)6, 4234-4241
    Online First (2024) DOI: 10.1021/jacs.3c13914

Publ.-Id: 38655

Impact of Viscosity on Human Hepatoma Spheroids in Soft Core-Shell Microcapsules

Peng, X.; Janićijević, Ž.; Lemm, S.; Hauser, S.; Knobel, M.; Pietzsch, J.; Bachmann, M.; Baraban, L.

The extracellular environment regulates the structures and functions of cells, from the molecular to the tissue level. However, the underlying mechanisms influencing the organization and adaptation of cancer in three-dimensional (3D) environments are not yet fully understood. In this study, the influence of the viscosity of the environment is investigated on the mechanical adaptability of human hepatoma cell (HepG2) spheroids in vitro, using 3D microcapsule reactors formed with droplet-based microfluidics. To mimic the environment with different mechanical properties, HepG2 cells are encapsulated in alginate core–shell reservoirs (i.e., microcapsules) with different core viscosities tuned by incorporating carboxymethylcellulose. The significant changes in cell and spheroid distribution, proliferation, and cytoskeleton are observed and quantified. Importantly, changes in the expression and distribution of F-actin and keratin 8 indicate the relation between spheroid stiffness and viscosity of the surrounding medium. The increase of F-actin levels in the viscous medium can indicate an enhanced ability of tumor cells to traverse dense tissue. These results demonstrate the ability of cancer cells to dynamically adapt to the changes in extracellular viscosity, which is an important physical cue regulating tumor development, and thus of relevance in cancer biology.

Keywords: hepatoma spheroids; cell adaptation; cytoskeleton; tumor microenvironment; hydrogel microcapsule

Publ.-Id: 38654

Data publication: AFLOW-CCE for the thermodynamics of ionic materials

Friedrich, R.; Curtarolo, S.

The data set contains the calculated results from which the formation enthalpies have been calculated.

Related publications

  • Reseach data in external data repository
    Publication year 2024
    License: CC BY; Creative Commons Attribution 4.0 International
    Hosted on Link to location
    DOI: 10.1063/5.0184917

Publ.-Id: 38653

AFLOW-CCE for the thermodynamics of ionic materials

Friedrich, R.; Curtarolo, S.

Accurate thermodynamic stability predictions enable data-driven computational materials design. Standard density functional theory
(DFT) approximations have limited accuracy with average errors of a few hundred meV/atom for ionic materials, such as oxides
and nitrides. Thus, insightful correction schemes as given by the coordination corrected enthalpies (CCE) method, based on an intuitive
parametrization of DFT errors with respect to coordination numbers and cation oxidation states, present a simple, yet accurate
solution to enable materials stability assessments. Here, we illustrate the computational capabilities of our AFLOW-CCE software by
utilizing our previous results for oxides and introducing new results for nitrides. The implementation reduces the deviations between
theory and experiment to the order of the room temperature thermal energy scale, i.e., ∼25 meV/atom. The automated corrections
for both materials classes are freely available within the AFLOW ecosystem via the AFLOW-CCE module, requiring only structural

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Publ.-Id: 38652

A survey of practice patterns for real-time intrafractional motion-management in particle therapy

Zhang, Y.; Trnkova, P.; Toshito, T.; Heijmen, B.; Richter, C.; Aznar, M.; Albertini, F.; Bolsi, A.; Daartz, J.; Bertholet, J.; Knopf, A.

Background and purpose: Organ motion compromises accurate particle therapy delivery. This study reports on the practice patterns for real-time intrafractional motion-management in particle therapy to evaluate current clinical practice and wishes and barriers to implementation.
Materials and methods: An institutional questionnaire was distributed to particle therapy centres worldwide (7/ 2020–6/2021) asking which type(s) of real-time respiratory motion management (RRMM) methods were used, for which treatment sites, and what were the wishes and barriers to implementation. This was followed by a three-round DELPHI consensus analysis (10/2022) to define recommendations on required actions and future vision. With 70 responses from 17 countries, response rate was 100% for Europe (23/23 centres), 96% for Japan (22/23) and 53% for USA (20/38).
Results: Of the 68 clinically operational centres, 85% used RRMM, with 41% using both rescanning and active methods. Sixty-four percent used active-RRMM for at least one treatment site, mostly with gating guided by an external marker. Forty-eight percent of active-RRMM users wished to expand or change their RRMM technique. The main barriers were technical limitations and limited resources. From the DELPHI analysis, optimisation of rescanning parameters, improvement of motion models, and pre-treatment 4D evaluation were unanimously
considered clinically important future focus. 4D dose calculation was identified as the top requirement for future commercial treatment planning software.
Conclusion: A majority of particle therapy centres have implemented RRMM. Still, further development and clinical integration were desired by most centres. Joint industry, clinical and research efforts are needed to translate innovation into efficient workflows for broad-scale implementation.

Keywords: Particle/proton therapy; Intrafraction motion; Real-time respiratory motion management; Image-guided particle therapy; Rescanning

Publ.-Id: 38649

A survey of practice patterns for adaptive particle therapy for interfractional changes

Trnkova, P.; Zhang, Y.; Toshito, T.; Heijmen, B.; Richter, C.; Aznar, M. C.; Albertini, F.; Bolsi, A.; Daartz, J.; Knopf, A. C.; Bertholet, J.

Background and purpose: Anatomical changes may compromise the planned target coverage and organs-at-risk dose in particle therapy. This study reports on the practice patterns for adaptive particle therapy (APT) to evaluate current clinical practice and wishes and barriers to further implementation. Materials and methods: An institutional questionnaire was distributed to PT centres worldwide (7/2020–6/2021) asking which type of APT was used, details of the workflow, and what the wishes and barriers to implementation were. Seventy centres from 17 countries participated. A three-round Delphi consensus analysis (10/2022) among the authors followed to define recommendations on required actions and future vision.
Results: Out of the 68 clinically operational centres, 84% were users of APT for at least one treatment site with head and neck being most common. APT was mostly performed offline with only two online APT users (plan-library). No centre used online daily re-planning. Daily 3D imaging was used for APT by 19% of users. Sixty-eight percent of users had plans to increase their use or change their technique for APT. The main barrier was “lack of integrated and efficient workflows”. Automation and speed, reliable dose deformation for dose accumulation and
higher quality of in-room volumetric imaging were identified as the most urgent task for clinical implementation of online daily APT.
Conclusion: Offline APT was implemented by the majority of PT centres. Joint efforts between industry research and clinics are needed to translate innovations into efficient and clinically feasible workflows for broad-scale implementation of online APT.

Keywords: Particle/proton therapy; Adaptive radiotherapy (ART); Interfraction anatomical variation; Image guided particle therapy; Adaptive treatment planning

Publ.-Id: 38648

DNA-Methylome–Based Tumor Hypoxia Classifier Identifies HPV-Negative Head and Neck Cancer Patients at Risk for Locoregional Recurrence after Primary Radiochemotherapy

Tawk, B.; Rein, K.; Schwager, C.; Knoll, M.; Wirkner, U.; Hörner-Rieber, J.; Liermann, J.; Kurth, I.; Balermpas, P.; Rödel, C.; Linge, A.; Löck, S.; Lohaus, F.; Tinhofer, I.; Krause, M.; Stuschke, M.; Ligia Grosu, A.; Zips, D.; Combs, S. E.; Belka, C.; Stenzinger, A.; Herold-Mende, C.; Baumann, M.; Schirmacher, P.; Debus, J.; Abdollahi, A.

Purpose: Tumor hypoxia is a paradigmatic negative prognosticator of treatment resistance in head and neck squamous cell carcinoma (HNSCC). The lack of robust and reliable hypoxia
classifiers limits the adaptation of stratified therapies. We hypothesized that the tumor DNA methylation landscape might indicate epigenetic reprogramming induced by chronic intratumoral hypoxia. Experimental Design: A DNA-methylome–based tumor hypoxia classifier (Hypoxia-M) was trained in the TCGA (The Cancer Genome Atlas)-HNSCC cohort based on matched assignments using gene expression–based signatures of hypoxia (Hypoxia-GES). Hypoxia-M was validated in a multicenter DKTK-ROG trial consisting of human papillomavirus (HPV)–negative patients with HNSCC treated with primary radiochemotherapy (RCHT).

Results: Although hypoxia-GES failed to stratify patients in the DKTK-ROG, Hypoxia-M was independently prognostic for local recurrence (HR, 4.3; P ¼0.001) and overall survival (HR, 2.34; P ¼ 0.03) but not distant metastasis after RCHT in both cohorts. Hypoxia-M status was inversely associated with CD8 T-cell infiltration in both cohorts. Hypoxia-M was further prognostic in the TCGA-PanCancer cohort (HR, 1.83; P ¼0.04), underscoring the breadth of this classifier for predicting tumor hypoxia status.

Conclusions: Our findings highlight an unexplored avenue for DNA methylation–based classifiers as biomarkers of tumoral hypoxia for identifying high-risk features in patients with HNSCC

Publ.-Id: 38647

Consensus guide on CT-based prediction of stopping-power ratio using a Hounsfield look-up table for proton therapy

Peters, N.; Trier Taasti, V.; Ackermann, B.; Bolsi, A.; Vallhagen Dahlgren, C.; Ellerbrock, M.; Fracchiolla, F.; Gomà, C.; Góra, J.; Cambraia Lopes, P.; Rinaldi, I.; Salvo, K.; Sojat Tarp, I.; Vai, A.; Bortfeld, T.; Lomax, A.; Richter, C.; Wohlfahrt, P.

Background and purpose: Studies have shown large variations in stopping-power ratio (SPR) prediction from computed tomography (CT) across European proton centres. To standardise this process, a step-by-step guide on specifying a Hounsfield look-up table (HLUT) is presented here. Materials and methods: The HLUT specification process is divided into six steps: Phantom setup, CT acquisition, CT number extraction, SPR determination, HLUT specification, and HLUT validation. Appropriate CT phantoms have a head- and body-sized part, with tissue-equivalent inserts in regard to X-ray and proton interactions. CT numbers are extracted from a region-of-interest covering the inner 70% of each insert in-plane and several axial CT slices in scan direction. For optimal HLUT specification, the SPR of phantom inserts is measured in a proton beam and the SPR of tabulated human tissues is computed stoichiometrically at 100 MeV. Including both phantom inserts and tabulated human tissues increases HLUT stability. Piecewise linear regressions are performed between CT numbers and SPRs for four tissue groups (lung, adipose, soft tissue, and bone) and then connected with straight lines. Finally, a thorough but simple validation is performed. Results: The best practices and individual challenges are explained comprehensively for each step. A well-defined strategy for specifying the connection points between the individual line segments of the HLUT is presented. The guide was tested exemplarily on three CT scanners from different vendors, proving its feasibility. Conclusion: The presented step-by-step guide for CT-based HLUT specification with recommendations and examples can contribute to reduce inter-centre variations in SPR prediction.

Keywords: Hounsfield look-up table; Proton therapy; Single-energy CT; Stoichiometric calibration; Stopping-power ratio; Proton range prediction

Publ.-Id: 38646

The role of ESTRO guidelines in achieving consistency and quality in clinical radiation oncology practice

Vrou Offersen, B.; Aznar, M. C.; Bacchus, C.; Coppes, R. P.; Deutsch, E.; Georg, D.; Haustermans, K.; Hoskin, P.; Krause, M.; Lartigau, E. F.; Lee, A. W. M.; Löck, S.; Thwaites, D. I.; van der Kogel, A. J.; van der Heide, U.; Valentini, V.; Overgaard, J.; Baumann, M.

In summary, ESTRO clinical and other guidelines are soundly based, but always require validation, careful and consistent implementation, and focused education and training on their use, as well as local monitoring of that. As guidelines develop and older ones become superseded, there should be a clear mechanism to inform the community of the status of specific guidelines, especially when they have been replaced by new or updated versions. An important scientific aim for the future is to further advance guidelines and their individual statements into fully evidence-based instruments. These, in principle, could be directly linked to growing data-bases, allowing feedback mechanisms and thus continuous optimization. Another challenging research topic is the interplay of guidelines with growing opportunities and demands of personalized approaches of treatment.


Publ.-Id: 38645

Influence of Bruton’s Tyrosine Kinase (BTK) on Epithelial–Mesenchymal Transition (EMT) Processes and Cancer Stem Cell (CSC) Enrichment in Head and Neck Squamous Cell Carcinoma (HNSCC)

Leichtle, F.; Betzler, A. C.; Eizenberger, C.; Lesakova, K.; Ezic, J.; Drees, R.; Greve, J.; Schuler, P. J.; Laban, S.; Hoffmann, T. K.; Cordes, N.; Lavitrano, M.; Grassilli, E.; Brunner, C.

Constitutively active kinases play a crucial role in carcinogenesis, and their inhibition is a common target for molecular tumor therapy. We recently discovered the expression of two oncogenic isoforms of Bruton’s Tyrosine Kinase (BTK) in head and neck squamous cell carcinoma (HNSCC), Btk-p80 and BTK-p65. However, the precise role of BTK in HNSCC remains unclear. Analyses of a tissue microarray containing benign and malignant as well as inflammatory tissue samples of the head and neck region revealed the preferential expression of BTK-p80 in malignant tissue, whereas BTK-p65 expression was confirmed in over 80% of analyzed metastatic head and neck tumor cases. Therefore, processes associated with metastasis, like cancer stem cell (CSC) enrichment and the epithelial–mesenchymal transition (EMT), which in turn depend on an appropriate cytokine milieu, were analyzed. Treatment of HNSCC-derived cell lines cultured under 3D conditions with the BTK inhibitor AVL-292 caused reduced sphere formation, which was accompanied by reduced numbers of ALDH1A1+ CSCs as well as biological changes associated with the EMT. Moreover, we observed reduced NF-κB expression as well as altered NF-κB dependent pro-tumorigenic and EMT-associated cytokine release of IL-6, IFNγ, and TNFα when BTK activity was dampened. Therefore, an autocrine regulation of the oncogenic BTK-dependent process in HNSCC can be suggested, with BTK inhibition
expected to be an effective treatment option for HNSCC.

Keywords: BTK; CSC; EMT; HNSCC

Publ.-Id: 38644

Prognostic biomarkers for the response to the radiosensitizer nimorazole combined with RCTx: a pre-clinical trial in HNSCC xenografts

Koi, L.; Bitto, V.; Weise, C.; Möbius, L.; Linge, A.; Löck, S.; Yaromina, A.; José Besso, M.; Valentini, C.; Pfeifer, M.; Overgaard, J.; Zips, D.; Kurth, I.; Krause, M.; Baumann, M.

Background Tumor hypoxia is associated with resistance to radiotherapy and chemotherapy. In head and neck squamous cell carcinoma (HNSCC), nimorazole, an oxygen mimic, combined with radiotherapy (RT) enabled to improve loco-regional control (LRC) in some patients with hypoxic tumors but it is unknown whether this holds also for radio-
chemotherapy (RCTx). Here, we investigated the impact of nimorazole combined with RCTx in HNSCC xenografts and explored molecular biomarkers for its targeted use.
Methods Irradiations were performed with 30 fractions in 6 weeks combined with weekly cisplatin. Nimorazole was applied before each fraction, beginning with the first or after ten fractions. Effect of RCTx with or without addition of nimorazole was quantified as permanent local control after irradiation. For histological evaluation and targeted gene expression analysis, tumors were excised untreated or after ten fractions. Using quantitative image analysis, micromilieu parameters were determined. Results Nimorazole combined with RCTx significantly improved permanent local control in two tumor models, and showed a potential improvement in two additional models. In these four models, pimonidazole hypoxic volume (pHV) was significantly reduced after ten fractions of RCTx alone. Our results suggest that nimorazole combined with RCTx might improve TCR compared to RCTx alone if hypoxia is decreased during the course of RCTx but further experiments are warranted to verify this association. Differential gene expression analysis revealed 12 genes as potential for RCTx response. When evaluated in patients with HNSCC who were treated with primary RCTx, these genes were predictive for LRC. Conclusions Nimorazole combined with RCTx improved local tumor control in some but not in all HNSCC xeno-grafts. We identified prognostic biomarkers with the potential for translation to patients with HNSCC.

Keywords: HNSCC; Biom; Nimorazole; Radiosensitizer; Radiochemotherapy; Radiotherapy; Radioresistance; Hypoxia

Publ.-Id: 38643

Dynamics of CXCR4 positive circulating tumor cells in prostate cancer patients during radiotherapy

Klusa, D.; Lohaus, F.; Franken, A.; Baumbach, M.; Cojoc, M.; Dowling, P.; Linge, A.; Offermann, A.; Löck, S.; Husman, D.; Rivandi, M.; Polzer, B.; Freytag, V.; Lange, T.; Neubauer, H.; Kücken, M.; Perner, S.; Hölscher, T.; Dubrovska, A.; Krause, M.; Kurth, I.; Baumann, M.; Peitzsch, C.

Ablative radiotherapy is a highly efficient treatment modality for patients with metastatic prostate cancer (PCa). However, a subset of patients does not respond. Currently, this subgroup with bad prognosis cannot be identified before disease progression. We hypothesize that markers indicative of radioresistance, stemness and/or bone tropism may have a prognostic potential to identify patients profiting from metastases-directed radiotherapy. Therefore, circulating tumor cells (CTCs) were analyzed in patients with metastatic PCa (n = 24) during radiotherapy with Cell-Search, multicolor flow cytometry and imaging cytometry. Analysis of copy-number alteration indicates a polyclonal CTC population that changes after radiotherapy.
CTCs were found in 8 out of 24 patients (33.3%) and were associated with a shorter time to biochemical progression after radiotherapy. Whereas the total CTC count dropped after radiotherapy, a chemokine receptor CXCR4-expressing subpopulation representing 28.6% of the total CTC population remained stable up to 3 months. At once, we observed higher chemokine CCL2 plasma concentrations and proinflammatory monocytes. Additional functional analyses demonstrated key roles of CXCR4 and CCL2 for cellular radiosensitivity, tumorigenicity and stem-like potential in vitro and in vivo. Moreover, a high CXCR4 and CCL2 expression was found in bone metastasis biopsies of PCa patients. In summary, panCK+CXCR4+ CTCs may have a prognostic potential in patients with metastatic PCa treated with metastasis-directed radiotherapy.

Keywords: bone metastasis; radiotherapy; prostate cancer; CXCR4; circulating tumor cells

Publ.-Id: 38640

Direct visualization of proton beam irradiation effects in liquids by MRI

Gantz, S.; Karsch, L.; Pawelke, J.; Schieferecke, J.; Schellhammer, S.; Smeets, J.; Van Der Kraaij, E.; Hoffmann, A. L.

The main advantage proton beams offer over photon beams in radiation therapy of cancer patients is the dose maximum at their finite range, yielding a reduction in the dose deposited in healthy tissues surrounding the tumor. Since no direct method exists to measure the beam’s range during dose delivery, safety margins around the tumor are applied, compromising the dose conformality and reducing the targeting accuracy. Here, we demonstrate that online MRI can visualize the proton beam and reveal its range during irradiation of liquid-filled phantoms. A clear dependence on beam energy and current was found. These results stimulate research into novel MRI-detectable beam signatures and already find application in the geometric quality assurance for magnetic resonance-integrated proton therapy systems currently under development.

Keywords: cancer radiation treatment; proton beam therapy; MRI; beam visualization

Publ.-Id: 38638

Efficient Radial-Shell Model for 3D Tumor Spheroid Dynamics with Radiotherapy

Franke, F.; Michlikova, S.; Aland, S.; Kunz-Schughart, L. A.; Voss-Böhme, A.; Lange, S.

Understanding the complex dynamics of tumor growth to develop more efficient therapeutic strategies is one of the most challenging problems in biomedicine. Three-dimensional (3D) tumor spheroids, reflecting avascular microregions within a tumor, are an advanced in vitro model system to assess the curative effect of combinatorial radio(chemo)therapy. Tumor spheroids exhibit particular crucial pathophysiological characteristics such as a radial oxygen gradient that critically affect the sensitivity of the malignant cell population to treatment. However, spheroid experiments remain laborious, and determining long-term radio(chemo)therapy outcomes is challenging. Mathematical models of spheroid dynamics have the potential to enhance the informative value of experimental data, and can support study design; however, they typically face one of two limitations: while non-spatial models are computationally cheap, they lack the spatial resolution to predict oxygen-dependent radioresponse, whereas models that describe spatial cell dynamics are computationally expensive and often heavily parameterized, impeding the required calibration to experimental data. Here, we present an effectively one-dimensional mathematical model based on the cell dynamics within and across radial spheres which fully incorporates the 3D dynamics of tumor spheroids by exploiting their approximate rotational symmetry. We demonstrate that this radial-shell (RS) model reproduces experimental spheroid growth curves of several cell lines with and without radiotherapy, showing equal or better performance than published models such as 3D agent-based models. Notably, the RS model is sufficiently efficient to enable multi-parametric optimization within previously reported and/or physiologically reasonable ranges based on experimental data. Analysis of the model reveals that the characteristic change of dynamics observed in experiments at small spheroid volume originates from the spatial scale of cell interactions. Based on the calibrated parameters, we predict the spheroid volumes at which this behavior should be observable. Finally, we demonstrate how the generic parameterization of the model allows direct parameter transfer to 3D agent-based models.

Keywords: spheroids; spatio-temporal mathematical modelling; minimal model; tumor relapse; systems biology; simulation; radiation therapy; 3D growth; growth curve; radial shell model; cellular automaton

Publ.-Id: 38637

Artificial intelligence in cancer research and precision medicine: Applications, limitations and priorities to drive transformation in the delivery of equitable and unbiased care

Corti, C.; Cobanaj, M.; Dee, E. C.; Criscitiello, C.; Tolaney, S. M.; Celi, L. A.; Curigliano, G.

Artificial intelligence (AI) has experienced explosive growth in oncology and related specialties in recent years. The improved expertise in data capture, the increased capacity for data aggregation and analytic power, along with decreasing costs of genome sequencing and related biologic “omics”, set the foundation and need for novel tools that can meaningfully process these data from multiple sources and of varying types. These advances provide value across biomedical discovery, diagnosis, prognosis, treatment, and prevention, in a multimodal
fashion. However, while big data and AI tools have already revolutionized many fields, medicine has partially lagged due to its complexity and multi-dimensionality, leading to technical challenges in developing and validating solutions that generalize to diverse populations. Indeed, inner biases and miseducation of algorithms, in view of their implementation in daily clinical practice, are increasingly relevant concerns; critically, it is possible for AI to mirror the unconscious biases of the humans who generated these algorithms. Therefore, to avoid worsening existing health disparities, it is critical to employ a thoughtful, transparent, and inclusive approach that involves addressing bias in algorithm design and implementation along the cancer care continuum.
In this review, a broad landscape of major applications of AI in cancer care is provided, with a focus on cancer
research and precision medicine. Major challenges posed by the implementation of AI in the clinical setting will
be discussed. Potentially feasible solutions for mitigating bias are provided, in the light of promoting cancer
health equity.

Keywords: Artificial intelligence; Precision medicine; Equity; Outcome prediction; Decision support; Bias

Publ.-Id: 38636

Are hybrid conferences the new standard?

Baumann, M.; Bacchus, C.; Aznar, M. C.; Coppes, R. P.; Deutsch, E.; Georg, D.; Haustermans, K.; Hoskin, P.; Krause, M.; Lartigau, E. F.; Lee, A. W. M.; Löck, S.; Offersen, B. V.; Overgaard, J.; Thwaites, D. I.; van der Kogel, A. J.; van der Heide, U. A.; Valentini, V.

This issue includes a perspective contribution by Lefresne et al. [1] on face-to-face scientific conferences versus virtual meetings and the implications for climate change. Generally, it is the policy of the Green Journal not to publish contributions with non-scientific content. In this specific case, the editors believe that the contribution by Lefresne and colleagues raises an important point that needs careful consideration and discussion in our scientific community. As scientists, we are at the forefront of research and strive to positively shape the future for humankind. Therefore, it is of key importance that the environmental impact of scientific activities is considered, and that our community develops and contributes to solutions to prevent further exacerbation of climate change with its substantial impact on health-related issues. This includes that pros and cons of face-to-face scientific meetings are carefully weighed.


Publ.-Id: 38635

Fabrication, defect chemistry and microstructure of Mn‑doped UO2

Smith, H.; Townsend, L. T.; Mohun, R.; Mosselmans, J. F. W.; Kvashnina, K.; Neil, C. H.; Corkhill, C. L.

Mn-doped UO2 is under consideration for use as an accident tolerant nuclear fuel. We detail the
synthesis of Mn-doped UO2 prepared via a wet co-precipitation method, which was refned to
improve the yield of incorporated Mn. To verify the Mn-doped UO2 defect chemistry, X-ray absorption
spectroscopy at the Mn K-edge was performed, in addition to X-ray difraction, Raman spectroscopy
and high-energy resolved fuorescence detection X-ray absorption near edge spectroscopy at the
U M4-edge. It was established that Mn2+ directly substitutes for U4+ in the UO2 lattice, accompanied
by oxygen vacancy (Ov) charge compensation. In contrast to other divalent-element doped UO2
materials, compelling evidence for U5+ in a charge compensating role was not found. This work
furthers understanding of the structure and crystal chemistry of Mn-doped UO2, which could show
potential advantages as a novel efcient advanced nuclear fuel.

Related publications

Publ.-Id: 38634

Order-parameter evolution in the Fulde-Ferrell-Larkin-Ovchinnikov phase

Molatta, S.; Kotte, T.; Opherden, D.; Koutroulakis, G.; Schlueter, J. A.; Zwicknagl, G.; Brown, S. E.; Wosnitza, J.; Kühne, H.

We report on the temperature dependence of the spatially modulated spin-polarization amplitude ΔKspin, which is a hallmark of the superconducting Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state. For that, we use 13C nuclear magnetic resonance (NMR) spectroscopy performed on the organic conductor β''-(ET)2SF5CH2CF2SO3. From a comparison of our experimental results to a comprehensive modeling of the 13C NMR spectra, we determine the evolution of ΔKspin upon condensation of the FFLO state. Further, the modeling of the spectra in the superconducting phase allows to quantify the decrease of the average spin susceptibility, stemming from the spin-singlet coupling of the superconducting electron pairs in the FFLO state of β''-(ET)SF5CH2CF2SO3.


  • Secondary publication expected from 22.01.2025

Publ.-Id: 38631

Defect nanostructure and its impact on magnetism of α-Cr2O3 thin films

Veremchuk, I.; Liedke, M. O.; Makushko, P.; Kosub, T.; Hedrich, N.; Pylypovskyi, O.; Ganss, F.; Butterling, M.; Hübner, R.; Hirschmann, E.; Elsherif, A. G. A.; Wagner, A.; Wagner, K.; Shields, B.; Maletinsky, P.; Faßbender, J.; Makarov, D.

Thin films of the magnetoelectric insulator α-Cr2O3 are technologically relevant for energy-efficient magnetic memory devices controlled by electric fields [1-3]. In contrast to single crystals, the quality of thin Cr2O3 films is usually compromised by the presence of point defects and their agglomerations at grain boundaries, putting into question their application potential. We experimentally investigated the defect nanostructure of magneton-sputtered 250-nm-thick Cr2O3 thin films prepared under different conditions on single crystals of Al2O3 (0001) and correlate it with the integral and local magnetic properties of the samples [4]. We evaluated the type and relative concentration of defects. For this purpose, positron annihilation spectroscopy (PAS) was used as a unique probe for open-volume defects in thin films. The results obtained for the thin-film samples are compared to single crystal data. Our analysis reveals that the Cr2O3 thin films are characterized by the presence of complex defects at grain boundaries, formed by groups of monovacancies, coexisting with monovacancies and dislocations. The concentration of complex defects can be controlled by the sample fabrication conditions. The defect nanostructure strongly affects the magnitude of the electrical readout, which is measured of the Cr2O3 samples capped with a thin layer of Pt relying on spin Hall effect [5]. Furthermore, the presence of larger defects like grain boundaries has a strong influence on the pinning of magnetic domain walls in thin films. Independent of these findings, we showed that the Néel temperature, which is one of the important technological metrics, is hardly affected by the formed defects in a broad range of deposition parameters.

[1] X. He, Y. Wang, N. Wu, A. N. Caruso, E. Vescovo, K. D. Belashchenko, P. A. Dowben, C. Binek, Nature Mater. 9, 579 (2010).
[2] T. Kosub, M. Kopte, R. Hühne, P. Appel, B. Shields, P. Maletinsky, R. Hübner, M. O. Liedke, J. Fassbender, O. G. Schmidt, D. Makarov, Nature Commun. 8, 13985 (2017).
[3] N. Hedrich, K. Wagner, O. V. Pylypovskyi, B. J. Shields, T. Kosub, D. D. Sheka, D. Makarov, P. Maletinsky, Nature Phys. 17, 574 (2021).
[4] I. Veremchuk, M. O. Liedke, P. Makushko, T. Kosub, N. Hedrich, O. V. Pylypovskyi, F. Ganss, M. Butterling, R. Hübner, E. Hirschmann, A. G. Attallah, A. Wagner, K. Wagner, B. Shields, P. Maletinsky, J. Fassbender, D. Makarov, Small 18, 2201228 (2022).
[5] R. Schlitz, T. Kosub, A. Thomas, S. Fabretti, K. Nielsch, D. Makarov, S. T. B. Goennenwein, Appl. Phys. Lett. 112, 132401 (2018).

  • Poster
    776. WE-Heraeus-Seminar: Re-thinking Spintronics: From Unconventional Materials to Novel Technologies, 04.-06.01.2023, Bad Honnef, Germany

Publ.-Id: 38627

Efficient Flotation of Engineered Artificial Minerals from Metallurgical Slags by Exploiting Interaction Scanning

Strube, F.; Rudolph, M.

FlotEnAMIS as part of SPP 2315 focuses on a novel functional atomic force microscopy (AFM) / atomic force spectroscopy and interface engineering based interaction scanning technology to understand the surface properties of engineered artificial minerals (EnAMs) in slags and find suitable flotation reagent regimes (including adsorption of collectors and modifiers/regulators/depressants) for an efficient flotation separation of fine particles from liberated fine grained engineered slags.

Keywords: interaction scanning; slags; atomic force microscopy; lithium

  • Lecture (others) (Online presentation)
    AG Grenzflächen, 23.08.2023, Freiberg, Deutschland

Publ.-Id: 38617

Zur flotativen Trennung von Lithium haltigen Mineralphasen in "engineered slag systems"

Strube, F.; Rudolph, M.

Die zunehmende Nutzung von Batterien für das Vorantreiben der Energiewende führt zu einem immer steigenden Bedarf an Lithium, welches bereits jetzt als kritischer Rohstoff gelistet ist. Die Sicherung vorhandener Lithiumquellen stellt jedoch noch eine Herausforderung dar. Lithium kann in Form von künstlichen Mineralien (EnAM – engineered aritifical minerals) in Schlacken angereichert und wiedergewonnen werden, welche beim pyrometallurgischen Recycling von Batterien anfallen. Durch die Anwendung bestimmter Temperatur- und Additivregime während des Recyclings lässt sich die Anreicherung von Lithium in EnAMs gezielt steuern (bspw. Kristallform, -größe und Phasenzusammensetzung). Das bekannteste Li-haltige EnAM ist Lithiumaluminat, welches unter anderem in das Gangmineral Gehlenit eingebettet ist. Die Trennung dieser EnAM-Phasen vom Gang kann durch Schaumflotation erreicht werden.
Im vorgestellten Projekt FlotEnAMIS, welches Teil des Schwerpunktprogramms 2315 der DFG ist, werden die Bestimmung der Phasenzusammensetzung und physikalisch-chemischen Eigenschaften von EnAMs in unterschiedlich behandelten Schlacken als wichtige Parameter für die Schaumflotation untersucht. Für die Charakterisierung der häufig fein verteilten Phasen werden Ergebnisse von Röntgendiffraktometrie (XRD), Röntgenfloureszenz (XRF), automatisierte Mineralogie (MLA) und Rasterkraftmikroskopie (AFM) miteinander in Verbindung gesetzt. Zur Beurteilung verschiedener wichtiger Oberflächenwechselwirkungen von Flotationsreagenzien in Abhängigkeit von Oberflächenpotentialen werden verschiedene AFM-Messungen mit hydrophilen und hydrophoben kolloidalen Sonden im Trocken- und Flüssigkeitsmodus an einem repräsentativen Modell durchgeführt und mit Ergebnissen aus Mikroflotationsexperimenten korreliert.

Keywords: Flotation; Lithium; Slag; Schlacke

  • Lecture (Conference)
    Tagung Aufbereitung und Recycling, 16.-17.11.2023, Freiberg, Deutschland

Publ.-Id: 38616

Development of Atomic Force Microscopy based interaction scanning modalities for the assessment of the flotation separation of Lithium bearing engineered artificial minerals in slags

Strube, F.; Rudolph, M.

Froth flotation is a widely established heterocoagulation separation process for the raw materials industry that is most efficient for particles in the size range of 20 μm – 200 μm. It is becoming even more important in upgrading critical materials. The key selection criterion is the difference in (de)wett(ing)ability of the surfaces of particulate phases. It has always been a grant challenge to quantitatively asses this complex physicochemical surface property. Most typically single mineral microflotation tests are found practical. They are further applied to find suitable reagent regimes necessary to condition the suspended particles in order to make selective separation possible. This involves various different suits of chemicals referred to as collectors and regulators. It is challenging if not impossible to obtain enough sample materials of pure individual phases to perform those conventional microflotation tests with unconventional resources, such as slags containing engineered artificial mineral (EnAM) phases enriched with critical elements. A prominent Li-containing EnAM is Lithiumaluminate and engineered in Al2O3-CaO-Li2O-MgO-(MnO)-SiO2 slag systems from battery recycling. We propose and develop an Atomic Force Microscopy based Interaction Scanning approach to be able to obtain surface interaction parameters at high resolution which are decisive for the particle-bubble-(non)attachments related to the dewettingability contrast.

As typical artificial phases in the mentioned slag system, we synthesize the valuable Lithiumaluminate and the gangue Gehlenite with high temperature sintering for evaluating interaction parameters and performing conventional microflotation tests of pure EnAM specimen. For assessing different key surface interactions from reagent regime depending surface potentials and surface hydrophizations we perform different hydrophilic and hydrophobic colloidal probe AFM measurements in dry and liquid mode on a representative model system with the valuable Lithium bearing mineral Spodumene and the representative gangue phase Quartz as substrates. This model system occurs in nature and is suitable to study reagents for efficient separation of Li-bearing minerals by flotation and to relate them to artificial phases such as EnAMs. The AFM studies are set in context with common micro flotation experiments and further characterization techniques. With this we will showcase and discuss the potentials of an Atomic Force Microscopy based approach to flotability assessment.
This project is part of the priority program PP2315 on engineered artificial minerals and their processing of the DFG (German Research Foundation).

Keywords: flotation; interaction scanning; atomic force microscopy; lithium

  • Poster
    International Congress on Particle Technology PARTEC, 26.-28.09.2023, Nürnberg, Deutschland

Publ.-Id: 38615

Efficient Flotation of Engineered Artificial Minerals from Metallurgical Slags by Exploiting Interaction Scanning, SPP2315, Yearly Meeting 2023

Strube, F.; Rudolph, M.

FlotEnAMIS as part of SPP 2315 focuses on a novel functional atomic force microscopy (AFM) / atomic force spectroscopy and interface engineering based interaction scanning technology to understand the surface properties of engineered artificial minerals (EnAMs) in slags and find suitable flotation reagent regimes (including adsorption of collectors and modifiers/regulators/depressants) for an efficient flotation separation of fine particles from liberated fine grained engineered slags.

Keywords: interaction scanning; flotation; slags; engineered artifical minerals; lithium

  • Lecture (others)
    SPP2315 annual meeting, 05.-06.07.2023, Freiberg, Deutschland

Publ.-Id: 38614

Data publication: Tunable Crystallinity and Electron Conduction in Wavy 2D Conjugated Metal-Organic Frameworks via Halogen Substitution

Jastrzembski, K.; Zhang, Y.; Lu, Y.; Sporrer, L.; Pohl, D.; Rellinghaus, B.; Waentig, A. L.; Zhang, H.; Mücke, D.; Fu, S.; Polozij, M.; Li, X.; Zhang, J.; Wang, M.; Morag, A.; Yu, M.; Mateo-Alonso, A.; Wang, H. I.; Bonn, M.; Kaiser, U.; Heine, T.; Dong, R.; Feng, X.

SinglePoint + band structure calculations for Cu3(HF-HH-cHBC)2 material using VASP software.

Keywords: 2D conjugated MOFs; conductive MOFs; halogen substitution; tunable crystallinity; wavy structure

Related publications

Publ.-Id: 38613

The use of AFM to study flotation parameters of Li bearing Engineered Artificial Minerals represented in slags

Strube, F.; Rudolph, M.

Due to the developments in electric mobility and the increased utilization of batteries, lithium has been classified as a critical raw material. It is a challenge to save and recycle existing lithium sources and the development of new recycling routes is a key area of research. A common method for the recycling of lithium ion batteries involves a pyrometallurgical high temperature treatment which concentrates critical elements in an alloy, whereas ignoble valuable metals such as lithium are concentrated in slags or dust. In order to use these Li-bearing slags as a promising lithium source, the priority programme PP2315 promotes the enrichment of lithium as engineered artificial mineral (EnAM). The most prominent Li-bearing EnAM is lithium aluminate which is found to be embedded in the gangue mineral gehlenite. The separation of these EnAM phases can be achieved via froth flotation, which is addressed in the presented project FlotEnAMIS as a part of the PP2315.
Froth flotation is a widely established separation process in the mining industry that is most efficient for particles in the size range of 20 μm – 200 μm. It is driven by the differences in the particle wettability and the attractive hydrophobic interaction between bubbles and particles at the solid-gas interface. This wettability difference can be controlled by selective adsorption of chemical reagents, such as collectors or depressants. Atomic force microscopy (AFM) can examine the differences in important driving forces of flotation acting between phases of certain hydrophobicity. For instance, colloidal probe AFM (CP-AFM) can be used as a model method to study the interaction of a sphere mimicking a bubble and a mineral surface.
The adsorption of surfactants on Li-EnAMs and the important sub-processes such as wettability, reagent adsorption, inter-particle interaction and bubble-particle interaction is investigated in this study by means of different AFM methods. The information obtained on the particle-reagent interaction is put in context with results of micro flotation studies. Based on this, suitable reagent regimes can be developed for the efficient recovery of lithium bearing minerals via flotation.

Keywords: slag; lithium; hydrophobicity; atomic force microscopy

  • Poster
    ProcessNet, 08.-10.03.2023, Frankfurt am Main, Deutschland

Publ.-Id: 38612

Magnetic Modelling of the Bjerkreim-Sokndal Layered Intrusion, Southern Norway

Lee, M.; Pastore, Z.; Church, N.; Madriz Diaz, Y. C.; Gloaguen, R.; McEnroe, S. A.

The Proterozoic Bjerkreim-Sokndal (BKS) is a 230 km2 layered intrusion in the Rogaland Anorthosite Province, Norway. BKS has been extensively explored for its critical mineral potential. The BKS has also been used as an analogue for planetary studies due to the presence of strong magnetic remanence, which has resulted in anomalies of up to 20 µT below background in airborne surveys. The BKS has five megacyclic lithological units, which are subdivided into zones based on specific mineralogy. The surficial location of these zones has been mapped based on limited outcrops due to difficult accessibility and regional airborne magnetics. However, review of recent high-resolution magnetic surveys suggests that the geologic map should be reassessed and used in conjunction with petrophysical data to better understand subsurface geometry. To address this challenge, we are developing a 3D geologic model that integrates multiscale geophysical data, from microscale lab measurements to regional airborne surveys. This includes data from a novel 2021 multicopter drone magnetic survey. A master ground sample database that includes over 3000 samples with in-situ and in-lab petrophysical measurements was compiled. The petrophysical database was analysed using Principal Component Analysis (PCA) clustering to distinguish relevant lithological units. PCA was performed using the variables: Density, Susceptibility, Natural Remanent Magnetization, Induced Magnetization, Koenigsberger Ratio, Declination, Inclination, Vx, Vy, Vz, and Residual Magnetic Field.

A combination of 2D forward and inversion modelling was implemented in Geosoft Oasis Montaj GM-SYS. The model was based on dense survey profiles orthogonal to geological strike along the eastern margin of the Bjerkreim lobe. Airborne magnetic data was used as the regional constraint and the petrophysical clusters as input data for the modelled blocks. The results were integrated into a 3D visualisation framework and used to refine the geometry of the main geological units. Visualisation of the high-resolution drone data shows complex structures beneath local lakes that were unmapped during previous geophysical surveys.

Keywords: Remanent Magnetization; Magnetics

  • Lecture (Conference)
    AGU23, 11.-15.12.2023, San Francisco, CA, United States of America

Publ.-Id: 38611

UAV geophysical surveys for mineral exploration in challenging environments

Madriz Diaz, Y. C.; Shaik Fareedh, J.; Gloaguen, R.; Dana Lee, M.; McEnroe, S. A.

Uncrewed aerial vehicles (UAVs) equipped with geophysical sensors have brought numerous advancements to modern geophysics, enabling cost-effective exploration and high-resolution analysis of geological anomalies. Integrating multiple sensors through UAV platforms proves especially advantageous in prospecting for mineral resources. Over the last years, our team has developed and rigorously tested in-house UAV systems carrying magnetometers, gamma-spectrometers, LiDAR, and hyperspectral sensors. Ensuring good data quality presents several challenges specific to UAVs. One significant challenge arises during aeromagnetic surveys conducted in regions with remarkably high magnetic gradients. These gradients have a substantial impact on the UAV’s essential navigation instruments, endangering the aircraft and leading to data disturbances. To showcase the potential of our approach, we have successfully deployed the systems in various challenging environments worldwide, including areas with high magnetic gradients, low GPS coverage, sharp topographic variations, extreme temperatures, and strong wind gusts.

We introduce a robust workflow designed to acquire and process UAV aeromagnetic data effectively. For the surveys, we employ the Sensys MagDrone R3 magnetometer strategically positioned at a 2m distance from the UAV using an extensible arm, eliminating magnetic interferences from the carrier. Additionally, data grids are meticulously designed based on the geological target, unraveling geological complexities. Data processing is performed through a Python toolbox, allowing us to promptly assess data quality during survey operations and to make well-informed decisions on-site. This approach has been validated across contrasting environments to tailor the acquisition strategy to local conditions, leading to the most optimal dataset possible at each location.

Through multiple case studies, we successfully demonstrate the capabilities of UAV magnetic surveys, often providing the highest resolution airborne survey data in the regions to date. The level of detail and accuracy achieved with UAV magnetic surveys opens up new possibilities for gaining deeper insights into complex structures and accurately pinpointing promising
mineral deposits with unprecedented precision.

Keywords: UAV; magnetics; magnetometer

  • Invited lecture (Conferences) (Online presentation)
    AGU23, 11.-15.12.2023, San Francisco, CA, United States

Publ.-Id: 38610

Positrons enable analysis of defects in functional materials

Liedke, M. O.; Butterling, M.; Hirschmann, E.; Elsherif, A. G. A.; Wagner, A.

Positron annihilation spectroscopy (PAS) is an advanced experimental technique that allows to study of extended and point defects and their agglomeration down to the atomic scale. The main strength of PAS is its excellent resolution to detect low concentrations (0.1 to 100 ppm) of vacancy-like defects. Using our slow positron beams at the positron ELBE (pELBE) facility, not only volumetric capability is achieved, but also defect profilometry over the depth of the sample in the sub-micron range. The other advantage of PAS is the interaction of positrons with core electrons, which carry information about the local atomic environment. The combination of all these characteristics allows the successful analysis of defect nanostructures in many classes of materials. Some research highlights will be presented, including investigations of the role of defects in heavily doped semiconductors, magneto-ionic oxides and nitrides, and superconductors. An overview of current collaborations within the HZDR and with external users will be given, as well as an outlook on future positron activities, including the increasing focus on kinematic pump-and-probe experiments associated with intense lasers and electric fields, and perspectives related to the upcoming DALI project.

Keywords: point defects; pores; positron annihilation spectroscopy

Related publications

  • Lecture (Conference)
    2023 HZDR Science Conference, 15.11.2023, Dresden, Germany

Publ.-Id: 38609

Defect landscape in TiO2 after ms-range annealing and resulting photocatalytic efficiency

Liedke, M. O.; Prucnal, S.; Butterling, M.; Hirschmann, E.; Gago, R.; David, G. C.; Rebohle, L.; Helm, M.; Zhou, S.; Wagner, A.

Transition metal oxides, particularly TiO2, are photoactive materials, which can be utilized to clean the air from pollutants and to produce green hydrogen for clean energy at the same time. They are one of the most promising candidates for high-performance photocatalysis. In this work, we investigate the effect of 20 ms flash lamp annealing (FLA) of sputter deposited TiO2, where arising from the light irradiation structural modifications of the films facilitates the photocatalytic (PC) degradation of two chemical compounds, namely methyl blue and methyl orange, once they interact with the surface of TiO2. The precise control of the flash energy input enables tuning of the TiO2 phase formation starting from pure anatase to mixed anatase/rutile phases, the latter associated with increased PC effect. Scanning electron microscopy and X-ray diffraction studies show that the crystal size and film quality increase with increasing annealing temperature. Further, the evolution of structural defects after FLA has been assessed by positron annihilation spectroscopy (PAS) and photoluminescence. Positron annihilation lifetime characteristics, i.e., positron lifetimes and their relative intensities profoundly sketch a transition between pure anatase and emerging rutile phase as a function of flash energy. Vacancy complexes close to the size of trivacancy dominate the anatase phase, whereas in the mixed anatase/rutile phase smaller open volume is evidenced, likely as a direct consequence of annealing. Finally, Doppler broadening PAS indicates the overall reduction of defect density exhibiting a similar transient phase region at the intermediate flash energies.

Keywords: transition metal oxides; photoactive materials; photocatalysis; flash lamp annealing; sputter deposition; positron annihilation spectroscopy

Related publications

  • Lecture (Conference)
    SLOPOS-16, The sixteenth International Workshop on Slow Positron Beam Techniques and applications, 16.07.2023, Orléans, France

Publ.-Id: 38608

Evolution of vacancy like defects in heavily doped GaAs

Liedke, M. O.; Prucnal, S.; Butterling, M.; Duan, J.; Hirschmann, E.; Wang, M.; Helm, M.; Zhou, S.; Wagner, A.; Dawidowski, W.; Boyu Young, L.; Hong, M.

N-type doping of GaAs is a self-limiting process where a carrier concentration in the
level of 1019 cm-3 is difficult to achieve. By means of ion implantation sequences with
precisely defined energy, homogenizing the distribution profile of dopants, followed
by non-equilibrium thermal annealing using intense light pulses, a highly doped ntype
GaAs with electron concentration easily exceeding the level of 5×1019 cm-3 was
obtained. Although, the absolute achieved carrier concentration has been
exceptionally large a peculiar variations of its magnitude across the samples
thickness have been observed, which we will regard to the incomplete
recrystallization processes. Moreover, we will discuss the effect of intense pulsed
laser melting and flash lamp annealing on defects distribution and electrical
activation efficiency in chalcogenide-implanted GaAs investigated by means of
positron annihilation spectroscopy, transport measurements, as well as
electrochemical capacitance-voltage techniques. Using positron beams, delivered by
the large scale facility ELBE at HZDR, as a sensitive probe of open volumes and
dedicated DFT calculations, we will highlight the capability of nanosecond pulsed
laser melting to control the type and density of defect complexes across the depth,
e.g. S or Te substitutions of As atoms associated to Ga vacancy, playing a crucial
role for donor deactivation. The distribution of defects and carriers will be discussed
considering the depth distribution of implanted elements and the solidification
velocity during recrystallization. The ultra-doped n-type GaAs is a potential candidate
for plasmonic and photonic applications. The proposed model for the donor-vacancy
formation during the PLM process of highly doped semiconductors is potentially
transferable to the group IV elements and groups III-V compound semiconductors.

Keywords: GaAs; pulsed laser melting; flash lamp annealing; positron annihilation spectroscopy

Related publications

  • Lecture (Conference)
    DPG Spring Meeting 2023, 20.03.2023, Dresden, Germany
  • Lecture (Conference)
    The 2023 Fall Meeting of the European Materials Research Society (E-MRS), 18.09.2023, Warsaw, Poland

Publ.-Id: 38607

Multi–length scale characterization of point defects in thermally oxidized, proton irradiated iron oxides

Lun Chan, H.; Auguste, R.; Romanovskaia, E.; Lopez Morales, A.; Liedke, M. O.; Schmidt, F.; Butterling, M.; Romanovski, V.; Winkler, C.; Qiu, J.; Wang, Y.; Kaoumi, D.; Selim, F. A.; Uberuaga, B. P.; Hirschmann, E.; Wagner, A.; Hosemann, P.; Scully, J. R.

A key for the success of safe nuclear power generation system is to consider structural materials that are economical, meet mechanical property needs, possess good corrosion resistance, and are radiation tolerant. Nevertheless, fundamental insights that elucidate the details of radiation damage on materials corrosion performance are lacking. This includes the behavior of surface oxides which often regulate corrosion. For example, it is unclear how non-equilibrium point defects, oxide structure, mass transport in oxides, and subsequent oxidation behavior are altered by the radiation. In this work, some of the effects of proton irradiation on the attributes of point defects, iron oxide microstructures, and the physical nature of the oxidation product were correlated with corrosion behavior. Iron oxides, fabricated by thermal oxidation in air at 400°C and 800°C for 1 h, were subjected to 200 keV, 0.03 dpa (displacements per atom) of proton irradiation, and subjected to corrosion reactivity assessment using AC and DC electrochemical methods. Experimental methods that target materials information at different length scales, such as positron annihilation spectroscopy (atomistic), transmission electron microscopy (mesoscopic), and electrochemical methods (macroscopic), were coupled to shed light on the impact of radiation-induced defect modifications and structural changes in oxides on corrosion reactivity which ultimately affects durability in harsh environments.

Keywords: proton irradiation; thermal oxidation; iron; corrosion; positron annihilation spectroscopy; point defects

Related publications


  • Secondary publication expected from 30.03.2024

Publ.-Id: 38606

UAV magnetics over the Bjerkreim-Sokndal Intrusion, Rogaland, Norway: A first look

Lee, M.; Madriz Diaz, Y. C.; Gloaguen, R.; McEnroe, S.

The Bjerkreim-Sokndal layered intrusion in Rogaland Anorthosite Province in southwestern Norway has been the focus of decades of research due to its complex geology, the presence of prominent remanent magnetic anomalies, and current economic interest in critical minerals. In 2021, collaborative geophysical fieldwork was conducted by the Norwegian University of Science and Technology and Helmholtz Institute Freiberg for Resource Technology. Despite challenging environmental conditions, more than 100 line-km of magnetic data were collected by a custom multirotor unmanned aerial vehicle (UAV) along the eastern margin of the Bjerkreim lobe of the Bjerkreim-Sokndal Intrusion. Data collection was focused over two areas. The first is an area in the south near the prominent Heskestad magnetic anomaly that is associated with large reversed magnetic remanence in a magnetite-ilmenite-gabbronorite unit. The second is an area in the north near Lake Teksevatnet that hosts mineralized zones and the Lauvneset magnetic anomaly. Initial analysis of the UAV-acquired magnetic data shows additional details on the geologic contacts of key units, especially where in-situ measurements are difficult to collect. UAV surveys help in the construction of an anomaly's geometry through incremental source-sensor separations at various flight altitudes above ground. The UAV data set is an intermediate step between ground and airborne surveys for multiscale interpretation and potentially extreme magnetic scales (from microscopic to planetary).

Keywords: airborne survey; magnetics; magnetometer; remanent magnetization


  • Secondary publication expected

Publ.-Id: 38604

Data publication: Thermal twin stars within a hybrid equation of state based on a nonlocal chiral quark model compatible with modern astrophysical observations

Carlomagno, J. P.; Contrera, G.; Grunfeld, A. G.; Blaschke, D.

These data sets characterize the thermodynamics of color superconducting quark matter under neutron star constraints and neutron star sequences at finite temperatures. They concern order parameters chiral condensate and diquark pairing gap as functions of chemical potential and temperature, phase diagrams in the temperature-chemical potential plane, mass-radius diagrams, mass as a function of the central energy density, equation of state, entropy per baryon versus pressure and chemical potential versus pressure.

Keywords: Chiral quark model; Thermal twin stars; QCD phase diagram; Color superconductivity; Multi-messenger astronomy; Quark-hadron phase transition

Related publications


Publ.-Id: 38593

Quasi-particle propagation across semiconductor-Mott insulator interfaces

Verlage, J.; Queißer, F.; Szpak, N.; König, J.; Kratzer, P.; Schützhold, R.

As a prototypical example for a heterostructure combining a weakly and a strongly interacting quantum many-body system, we study the interface between a semiconductor and a Mott insulator. Via the hierarchy of correlations, we derive and match the propagating or evanescent quasi-particle solutions on both sides. While the propagation is described by a band-like dispersion in both the weakly and the strongly interacting case, the inverse decay length across the interface follows a different dependence on the band gap in the Mott insulator and the semiconductor. As one consequence, tunnelling through a Mott insulating layer behaves quite different from a semiconducting (or band insulating) layer. For example, we find a strong suppression of tunnelling for energies in the middle between the upper and lower Hubbard band of the Mott insulator.

Publ.-Id: 38591

Electron probe petrochronology of monazite- and garnet-bearing metamorphic rocks in the Saxothuringian allochthonous domains (Erzgebirge, Granulite and Münchberg massifs)

Bernhard, S.; Krause, J.

In the Saxothuringian Zone, a unique assemblage of high- to ultra-high-pressure and ultra-high-temperature
metamorphic units is associated with medium- to low-pressure and temperature rocks. The units were
studied in a campaign with garnet and monazite petrochronology of gneisses, micaschists and phyllites, and
monazite dating in granites. P–T path segments of garnet crystallization were reconstructed by geothermobarometry
and interpreted in terms of the monazite stability field, EPMA Th–U–Pb monazite ages and garnet Y +
HREE zonations. One can recognize (1) Cambrian plutonism (512–503 Ma) with contact metamorphism in the
Münchberg Massif. Subordinate monazite populations may indicate a (2) widespread but weak Silurian (444–
418 Ma) thermal event. A (3) Devonian (389–360 Ma) high-pressure metamorphism prevails in the Münchberg
and Frankenberg massifs. In the ultra-high-pressure and high-pressure units of the Erzgebirge the predominant
(4) Carboniferous (336–327 Ma) monazites crystallized at the decompression paths. In the Saxonian Granulite
Massif, prograde–retrograde P–T paths of cordierite-garnet gneisses can be related to monazite ages from 339 to
317 Ma. A (5) local hydrothermal overprint at 313–302 Ma coincides partly with post-tectonic (345–307 Ma)
granite intrusions. Such diverse monazite age pattern and P–T time paths characterize the tectono-metamorphic
evolution of each crustal segment involved in the Variscan Orogeny.

Publ.-Id: 38590

Doublon-holon pair creation in Mott-Hubbard systems in analogy to QED

Queißer, F.; Krutitsky, K.; Navez, P.; Schützhold, R.

Via the hierarchy of correlations, we study doublon-holon pair creation in the Mott state of the Fermi-Hubbard model induced by a time-dependent electric field. Special emphasis is placed on the analogy to electron-positron pair creation from the vacuum in quantum electrodynamics (QED). We find that the accuracy of this analogy depends on the spin structure of the Mott background. For Ising type anti-ferromagnetic order, we derive an effective Dirac equation. A Mott state without any spin order, on the other hand, does not explicitly display such a quasi-relativistic behavior.

Publ.-Id: 38589

Higher-harmonic generation in the driven Mott-Hubbard model

Queißer, F.; Schützhold, R.

Using Floquet theory and the hierarchy of correlations, we study the non-equilibrium dynamics of the Mott insulator state in the Fermi-Hubbard model under the influence of a harmonically oscillating electric field representing the pump laser. After deriving the associated Floquet exponents, we consider higher-harmonic generation where the strongest signal is obtained if the driving frequency equals one third of the Mott gap.

Publ.-Id: 38588

In search of lost time: Raman thermochronology of FC‑1 zircon

Härtel, B.; Enkelmann, E.; Jonckheere, R.; Ludwig, T.; Krause, J.; Ratschbacher, L.

Translating thermochronological ages to geological models requires knowledge of the thermal sensitivity of the
applied thermochronometer, i.e. the closure temperature or the partial annealing/retention zone. Zircon Raman dating
is a thermochronometer that uses radiation-damage measurements and matched analyses of actinide contents in zircon.
Experimental work placed its closure temperature at 330–370 °C for the internal ν2(SiO4) and ν3(SiO4) Raman bands at 439
and 1008 cm−
1, and 260–310 °C for the external rotation (ER) band at 356 cm−
1. However, experimental annealing models
also predict partial radiation-damage annealing over a broad temperature range (> 500 °C). We test these closure temperatures
by dating zircon from the U–Pb reference material FC-1. We matched Raman-based radiation-damage measurements with U
and Th concentrations measured with a secondary ion mass spectrometer. The zircon Raman ages for the ν2, ν3, and ER bands
are 942 ± 23 Ma (2 s), 978 ± 38 Ma, and 1033 ± 32 Ma. This is lower than the expected range of 1040–1080 Ma, between the
apatite U–Pb (~ 490 °C) and zircon (U-Th)/He (ZHe; ~ 200 °C) ages. We discuss long-term, low-temperature annealing of
radiation damage during protracted cooling of the sample as a cause of age reduction. This explanation fits both, experimental
annealing models and zircon Raman data from other geological settings. Long-term, low-temperature annealing complicates
the interpretation of standalone zircon Raman data. However, exploiting this effect by combining zircon Raman and ZHe
dating on the same sample provides thermal-history information beyond that revealed by either of them.

Keywords: Zircon Raman dating; Closure temperature; Radiation-damage annealing; (U-Th)/He dating; Thermochronology

Publ.-Id: 38587

Preparation of 5‑[131I]iodotubercidin for the detection of adenosine kinase

Bier, D.; Holschbah, M.; Wedekind, F.; Sihver, W.; Drewes, B.; Schulze, A.; Neumaier, F.; Neumaier, B.; Bauer, A.

5-Iodotubercidin is a prototype adenosine kinase (AK) inhibitor with potent anti-seizure activity in rodent epilepsy models.
Using the chloramine-T method for radioiodination of tubercidin with 131I, we prepared no-carrier-added 5-[131I]iodotubercidin
(5-[131I]IT) in a radiochemical yield of 61 ± 13% and with a radiochemical purity of > 99% (molar activity = 10–40 GBq/
μmol). In vitro competition and saturation experiments demonstrated specific binding of 5-[131I]IT in rodent brain slices
(KD ~ 31 nM), but ex vivo autoradiography revealed its accumulation in cerebral vessels. We conclude that 5-[131I]IT could
be a useful tool for the detection and quantification of AK in in vitro studies.

Keywords: nucleoside adenosine kinase inhibitor (AKI); n.c.a. radioiodination; iodotubercidin; in vitro/ex vivo autoradiography

Publ.-Id: 38584

Fusion related laser plasma expertise and interests in the German Helmholtz Association

Schramm, U.

Presentation summing up the work of the Helmholtz task force AG Laser - the fusion energy options: Fusion related laser plasma expertise and interests in the German Helmholtz Association

  • Open Access Logo Invited lecture (Conferences)
    ELI Laser induced Fusion Kick-Off, 28.-29.11.2023, Dolni Brezani (Prag), Tschechien

Publ.-Id: 38582

Ion acceleration with ultrashort laser pulses: state-of-the-art and perspectives in the multi-PW regime

Schramm, U.

Talk on: Ion acceleration with ultrashort laser pulses: state-of-the-art and perspectives in the multi-PW regime

  • Open Access Logo Invited lecture (Conferences)
    Scientific opportunities with APOLLON facilities: from fundamental physics to societal applications workshop, 29.-30.11.2023, Paris, Frankreich

Publ.-Id: 38581

Data publication: LA-ICP-MS U-Pb cassiterite age data of the Sadisdorf deposit link Sn-Li-(W-Cu) mineralization in the eastern Erzgebirge to the collapse of the Altenberg-Teplice Caldera

Leopardi, D.; Gerdes, A.; Albert, R.; Gutzmer, J.; Lehmann, B.; Burisch, M.

This data repository contains sample overview photographs as well as the U-Pb LA-IC-MS measuring conditions, results and Tera-Wasserburg diagrams summarizing those results.

Keywords: U-Pb dating cassiterite; LA-ICP-MS

Related publications


Publ.-Id: 38580

Exploration of a mining residue from a high-Sulfidation epithermal gold Deposit

Bachmann, K.; Contreras Acosta, I. C.; Tolosana Delgado, R.; Gutzmer, J.

Reevaluating tailings material originating from a high-sulfidation epithermal gold deposit has unveiled the potential for a holistic remining endeavour. The primary objective of this operation would be the mitigation of minerals containing penalty elements, specifically sulphur in pyrrhotite, a major contributor to acid mine water drainage, alongside the concentration of precious elements like gold. Furthermore, exploring the applicability of the silicate fraction for industries such as ceramics, glass, and geopolymer production has been considered.
To accomplish these objectives, an initial drill core campaign featuring six drill holes was executed, accompanied by a thorough material characterization using automated mineralogy, geochemical assays, and hyperspectral analysis. The subsequent step involved a geometallurgical domaining process based on 64 geochemical assays, particle size measurements, and mineralogy assessments. A Mahalanobis distance hierarchical cluster analysis was employed to differentiate domains, and predictions for these domains were extended to all hyperspectral imaging samples.
The outcome of this comprehensive approach revealed the delineation of four distinct domains, each characterized by variations in modal mineralogy and trace elemental contents. This strategic analysis provides valuable insights into the heterogeneity of the tailings material, laying the groundwork for targeted interventions to address environmental concerns and maximize the extraction of valuable resources.

  • Invited lecture (Conferences) (Online presentation)
    Secondary Mineral Resources Characterization workshop, 25.-26.10.2023, Lund, Schweden

Publ.-Id: 38579

Deuterium burning measurement at LUNA and its astrophysical and nuclear implications

Cavanna, F.; Ciani, G. F.; Masha, E.; Piatti, D.

The D(p,γ)3He reaction is responsible for the deuterium destruction during the Big Bang Nucleosynthesis (BBN) and affects the primordial deuterium abundance. This latter is sensitive to fundamental cosmological parameters such as the baryon density and the effective number of relativistic species. In this paper, we describe the most precise direct measurement of the D(p,γ)3He reaction in the BBN energy range (Ecm = 30–280 keV) at the LUNA (Laboratory for Underground Nuclear Astrophysics) facility in Gran Sasso National Laboratories. Experimental results, cosmological consequences, and future prospects are reported here.

Keywords: Big bang Nucleosynthesis; deuterium abundance; underground nuclear astrophysics; cosmological constants

Publ.-Id: 38572

Distributor Effects on Liquid Hold-Up in Rotating Packed Beds

Pyka, T.; Bieberle, A.; Loll, R.; Held, C.; Schubert, M.; Schembecker, G.

Although it is known that a loss in separation performance is caused by liquid maldistribution, there is only marginal knowledge of liquid distribution in rotating packed beds (RPBs). As a result, the exact influence of the liquid distribution on separation performance in RPBs is not fully understood. Therefore, this study focuses on the influence of different liquid distributors on the liquid hold-up distribution of rotating metal foam packing inside RPBs. Liquid hold-ups were measured noninvasively using γ-ray computed tomography (CT), and water/air was the system under investigation, operated at atmospheric pressure, temperature of 20 °C, liquid flow rate of 60 l h^−1, F-factor of 2.3 Pa^0.5, and rotational speeds up to 900 rpm. For the first time, the liquid hold-up distribution in the axial direction of a rotating metal foam of an RPB could be accessed, which allowed the identification and quantification of occurring liquid accumulation at the rotor plates. Furthermore, the liquid hold-up distribution through the entire opaque packing could be visualized for different operating conditions by synchronizing the CT with the rotational speed of the rotor. The use of a single-point full-jet nozzle was more prone to cause liquid accumulation at the rotor plates than that with a rotating baffle distributor with 36 baffles. For comparison, circumferential liquid maldistribution was also observed by using a rotating baffle distributor with 12 baffles.

Keywords: rotating packed bed; process intensification; gamma-ray computed tomography

Related publications

Publ.-Id: 38570

Al-delta-doped ZnO films made by atomic layer deposition and flash-lamp annealing for low-emissivity coating

Zhang, G.; Steuer, O.; Li, R.; Cheng, Y.; Hübner, R.; Helm, M.; Zhou, S.; Liu, Y.; Prucnal, S.

In this work, we have investigated and optimized the Al-delta-doped ZnO (δ -AZO) superlattices for mid-infrared applications. Thin films of δ -AZO are fabricated by atomic layer deposition (ALD) followed by millisecond-range (ms-range) flash-lamp annealing (FLA). During the FLA process, the superlattice structure is preserved and Al is electrically activated. The highest carrier concentration and lowest resistivity estimated from Hall-effect measurements are 2.7 × 1021 cm−3 and 8.8 × 10-4 Ωcm, respectively, for the δ -AZO superlattice with an Al:Zn ratio of 1:20. Moreover, glass substrates coated with the developed δ -AZO superlattice show a reflectance above 60 % in the near- and mid-infrared spectral range, while the transmittance in the visible range maintains above 80 %. The presented δ -AZO superlattice is a good alternative material to replace indium tin oxide films for cost-efficient low-emissivity glazing.

Keywords: Al-doped ZnO; Delta-doping; Flash-lamp Annealing; Low-Emissivity coating

Related publications

Publ.-Id: 38568

NuScale-like SMR Model Development and Applied Safety Analyses with the Code Chain Serpent-DYN3D-ATHLET

Diaz Pescador, E.; Bilodid, Y.; Jobst, M.; Kliem, S.

NuScale is an integral pressurized water reactor (iPWR) operated with light water driven by natural circulation through two helical coil steam generators (HCSGs). This work reports the safety analyses of a boron dilution and steam line break accidental sequences in a developed plant computational model based on the specifications from the Final Safety Analysis Report (FSAR). Multi-physics calculations are performed with the code chain Serpent-DYN3D-ATHLET. A state-of-the-art multi-dimensional vessel topology is developed with ATHLET for the accurate representation of flow and temperature fields, as well as spatial core power distribution. The static calculation results show agreement with the reference values from the FSAR. The boron dilution sequence shows a homogeneous core power excursion by the boron feedback, and the reactor is tripped upon “high pressurizer pressure” signal. During the steam line break sequence, the affected HCSG depressurizes rapidly and the reactor is tripped upon “low main steam pressure” signal. None of the transients violate safety margins. The adopted 3-D vessel modelling approach and applied multi-physics calculations are able to capture both transient physics within the reactor domain, and conclude that symmetric arrangement of the HCSG tubes enhance coolant mixing and prevent a heterogeneous core power excursion.

Keywords: NuScale-SMR; iPWR; Boron dilution; Steam line break; Serpent-DYN3D-ATHLET


  • Secondary publication expected from 11.01.2025

Publ.-Id: 38564

Excitation of the Gyrotropic Mode in a Magnetic Vortex by Time-Varying Strain

Iurchuk, V.; Lindner, J.; Faßbender, J.; Kakay, A.

We demonstrate excitation of the gyrotropic mode in a magnetostrictive vortex by time-varying strain. The vortex dynamics is driven by a time-varying voltage applied to the piezoelectric substrate and detected electrically by spin rectification at subthreshold values of rf current. When the frequency of the time-varying strain matches the gyrotropic frequency at given in-plane magnetic field, the strain-induced in-plane magnetic anisotropy leads to a resonant excitation of the gyration dynamics in a magnetic vortex. We show that nonlinear gyrotropic dynamics can be excited already for moderate amplitudes of the time-varying strain.

Keywords: Magnetic vortices; Magnetoelastic effect; Spin dynamics; Micromagnetic modeling; Strain engineering

Publ.-Id: 38561

The impact of an ultrasonic standing wave on the sorption behavior of proteins: Investigation of the role of acoustically induced non-spherical bubble oscillations

Keshmiri, A.; Keshavarzi, B.; Eftekhari, M.; Heitkam, S.; Eckert, K.

Protein molecules adsorb on the air/liquid interface due to possessing a hydrophobic side. A full surface coverage is important in many processes such as in protein harvesting by foam fractionation. The adsorption of proteins in low concentration solutions is preceded by a relatively long time lag known as the induction period. This has been attributed to the formation of an adsorbed monolayer, which relies on the reorientation of the protein molecules. The reduction of the induction period can significantly facilitate the sorption process to reach full protein coverage. For this purpose acoustically induced non-spherical bubble oscillations can aid in the formation of the monolayer and enhance the sorption process.

In this study, low frequency ultrasound was used to induce non-spherical oscillations on an air bubble attached to a capillary. Profile analysis tensiometry was deployed to examine the effect of these non-spherical oscillations on the sorption dynamics of different proteins.

We observed that during the initial stages of adsorption, when the bubble surface is almost empty, non-spherical oscillations occur, which were found to significantly expedite the adsorption process. However, during later stages of the adsorption process, despite the continued presence of several sonication phenomena such as the primary radiation force and acoustic streaming, no change in adsorption behavior of the proteins could be noted. The occurrence, duration, and intensity of the non-spherical bubble oscillations appeared to be the sole contributing factors for the change of the sorption dynamics of proteins.

Keywords: Sorption on bubble; Protein sorption; Surface tension; Ultrasound; Non-spherical bubble oscillations; Microstreaming; Tensiometry; Acoustic bubble


Publ.-Id: 38559

Data publication: Hybrid star phenomenology from the properties of the special point

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

The columns of files EOS_TOV_etaV_etaD.TXT include central values of the baryonic chemical potential [MeV], pressure [MeV/fm^3], baryonic density [1/fm^3], radius [km] and mass [M_solar] of neutron stars modelled with hybrid quark-hadron equations of state constructed for the vector and diquark couplings etaV and etaD specified in the titles. The corresponding mass-radius diagrams are presented in Figs. 6-8 of the paper. The columns of the file etaV-etaD.TXT include diquark coupling and values of the vector coupling corresponding to the boundaries of the region providing the conditions of having the onset of deconfinement above the saturation density and stability of the quark branch of the mass-radius curve obtained as a solution of the TOV equation (see Fig. 7 of the paper).

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


Publ.-Id: 38558

Data publication: Thermodynamics of quark matter with multi-quark clusters

Blaschke, D.; Cierniak, M.; Ivanytskyi, O.; Röpke, G.

Results for phase shifts of pions as function of the pion energy at vanishing chemical potential for different temperatures and results for the densities and entropies of different particle species as a function of the temperature for different values of the scaled baryochemical potential mu/T=0, 1, 2, 3. Total pressure as a function of temperature for vanishing baryochemical potential.

Keywords: multi-quark clusters; Beth-Uhlenbeck approach; Mott dissociation; Polyakov-loop; quark matter thermodynamics

Related publications


Publ.-Id: 38557

Combining Cisplatin with Different Radiation Qualities—Interpretation of Cytotoxic Effects In Vitro by Isobolographic Analysis

Runge, R.; Reissig, F.; Herzog, N.; Oehme, L.; Brogsitter, C.; Kotzerke, J.

Background: The combination of platinum-containing cytostatic drugs with different
radiation qualities has been studied for years. Despite their massive side effects, these drugs still
belong to the therapeutic portfolio in cancer treatment. To overcome the disadvantages of cisplatin,
our study investigated the cytotoxic effects of combining radionuclides with cisplatin. Methods:
FaDu cells were treated with cisplatin (concentration ≈ 2 μM) and additionally irradiated after
two hours with the alpha-emitter 223Ra, the beta-emitter 188Re as well as external X-rays using
dose ranges of 2–6 Gy. Cell survival was followed by colony formation assays and plotted against
cisplatin concentration and radiation dose. The results were interpreted by isobolograms. Results:
Isobolographic analyses revealed a supra-additive cytotoxic effect for the combination of cisplatin
and 223Ra. A sub-additive effect was observed for the combination of cisplatin and 188Re, whereas
a protective effect was found for the combination with X-rays. Conclusions: The combination of
cisplatin and 223Ra may have the potential to create a successfully working therapy scheme for various
therapy approaches, whereas the combination with 188Re as well as single-dose X-ray treatment
did not lead to a detectable radiosensitizing effect. Thus, the combination with alpha-emitters
might be advantageous and, therefore, should be followed in future studies when combined with
cytostatic drugs.

Keywords: cisplatin; radionuclides; alpha-emitter; combined treatment; isobolograms

Publ.-Id: 38556

Uloga biofotonike u razvoju potenciometrijskih biosenzora i trodimenzionalnih mikrobioreaktora

Janićijević, Ž.

Kratko predavanje koje obuhvata moja istraživanja u domenu biosenzora i bioreaktora sa osvrtom na primenu fotonike u navedenim kontekstima. Uz diskusiju o samim temama istraživanja i njihovoj povezanosti sa fotonikom pridružena je i priča o krivudavom naučno-istraživačkom putu do trenutne pozicije.

Predavanje je održano na srpskom jeziku (engl. Serbian).

  • Lecture (others) (Online presentation)
    Dani Fotonike, 26.-27.12.2023, Belgrade, Serbia

Publ.-Id: 38553

A Multisensor Hyperspectral Benchmark Dataset For Unmixing of Intimate Mixtures

Koirala, B.; Rasti, B.; Bnoulkacem, Z.; de Lima Ribeiro, A.; Madriz Diaz, Y. C.; Herrmann, E.; Gestels, A.; de Kerf, T.; Lorenz, S.; Fuchs, M.; Janssens, K.; Steenackers, G.; Gloaguen, R.; Scheunders, P.

Optical hyperspectral cameras capture the spectral reflectance of materials. Since many materials behave as heterogeneous intimate mixtures with which each photon interacts differently, the relationship between spectral reflectance and material composition is very complex. Quantitative validation of spectral unmixing algorithms requires high-quality ground truth fractional abundance data, which are very difficult to obtain. In this work, we generated a comprehensive laboratory ground truth dataset of intimately mixed mineral powders. For this, five clay powders (Kaolin, Roof clay, Red clay, mixed clay, and Calcium hydroxide) were mixed homogeneously to prepare 325 samples of 60 binary, 150 ternary, 100 quaternary, and 15 quinary mixtures. Thirteen different hyperspectral sensors have been used to acquire the reflectance spectra of these mixtures in the visible, near, short, mid, and long-wavelength infrared regions (350-15385) nm. Overlaps in wavelength regions due to the operational ranges of each sensor and variations in acquisition conditions resulted in a large amount of spectral variability. Ground truth composition is given by construction, but to verify that the generated samples are sufficiently homogeneous, XRD and XRF elemental analysis is performed. We believe these data will be beneficial for validating advanced methods for nonlinear unmixing and material composition estimation, including studying spectral variability and training supervised unmixing approaches. The datasets can be downloaded from the following link:

Keywords: hyperspectral; intimate mixtures


Publ.-Id: 38552

An Extensive Multisensor Hyperspectral Benchmark Datasets of Intimate Mixtures of Mineral Powders

Koirala, B.; Rasti, B.; Bnoulkacem, Z.; de Lima Ribeiro, A.; Madriz Diaz, Y. C.; Herrmann, E.; Gestels, A.; de Kerf, T.; Janssens, K.; Steenackers, G.; Gloaguen, R.; Scheunders, P.

Since many materials behave as heterogeneous intimate mixtures with which each photon interacts differently, the relationship between spectral reflectance and material composition is very complex. Quantitative validation of spectral unmixing algorithms requires high-quality ground truth fractional abundance data, which are very difficult to obtain.In this work, we generated a comprehensive hyperspectral dataset of intimate mineral powder mixtures by homogeneously mixing five different clay powders (Kaolin, Roof clay, Red clay, mixed clay, and Calcium hydroxide). In total 325 samples were prepared. Among the 325 samples, 60 mixtures were binary, 150 were ternary, 100 were quaternary, and 15 were quinary. For each mixture (and pure clay powder), reflectance spectra are acquired by 13 different sensors, with a broad wavelength range between the visible and the long-wavelength infrared regions (i.e., between 350 nm and 15385 nm) and with a large variation in sensor types, platforms, and acquisition conditions. We will make this dataset public, to be used by the community for the validation of nonlinear unmixing methodologies (

  • Contribution to proceedings
    IGARSS 2023 - 2023 IEEE International Geoscience and Remote Sensing Symposium, 16.-21.07.2023, Pasadena, USA
    DOI: 10.1109/IGARSS52108.2023.10281467

Publ.-Id: 38550

Analyzing 3-phase Foams in Batch Flotation - A joint FWD-HIF Study

Marquardt, T.; Jähnigen, P.; Lappan, T.; Heitkam, S.; Eckert, K.; Hassan, A.; Pereira, L.; Rudolph, M.

Froth flotation, widely used in the processing and recycling of ores and raw materials, employs hydrophobic interactions between bubbles and particles to concentrate valuable materials in an overflowing froth phase. The flotation process, and therefore the quality of separation, is affected by the height of the 3-phase foam, called froth, and thus by the foamability. Within a joint European industry doctorate program between the Institute of Fluid Dynamics, HIF and TU Dresden, we have carried out a collaborative measurement campaign to collect data for modeling flotation subprocesses under varying hydrodynamic and reagent conditions using a laboratory scale flotation cell and a binary pyrite-quartz particle system. Froth phase measurements included the recording of the froth height through the transparent side wall of the flotation cell and imaging of the froth surface as well as foamability measurements of feed and tailing samples by means of dynamic foam analysis and measurement of the liquid fraction of the froth based on its electrical conductivity. Preliminary results show a significant change in froth properties during the flotation process from a particle-laden froth to finer bubbles containing fewer particles. Further data analysis is planned to investigate the influence of frother and collector concentrations as well as air flow rate and impeller tip speed on the foamability and froth height, impacting the recovery and grade of minerals. Such joint froth studies between the Institute of Fluid Dynamics and HIF belong to the sciences cases perspectively to be intensified by CeRI2, one of the HZDR research infrastructure projects.

  • Lecture (Conference)
    HZDR Science Conference, 15.-16.11.2023, Dresden, Deutschland

Publ.-Id: 38549

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