Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Achieving efficient, high-power harmonic generation in the terahertz (THz) spectral domain has technological applications, for example in sixth generation (6G) communication networks [1, 2]. Massless Dirac fermions possess extremely large THz nonlinear susceptibilities and harmonic conversion efficiencies [3–7]. However, the observed maximum generated harmonic power is limited, because of saturation effects at increasing incident powers, as shown recently for graphene [8]. Here, we demonstrate room-temperature THz harmonic generation in a Bi2Se3 topological insulator (TI) and TI-grating metamaterial structures with surface-selective THz field enhancement. We obtain a third-harmonic power approaching the milliwatt range for an incident power of 75 mW – an improvement by two orders of magnitude compared to a benchmarked graphene sample. We establish a framework in which this exceptional performance is the result of thermodynamic harmonic generation by the massless topological surface states, benefiting from ultrafast dissipation of electronic heat via surface-bulk Coulomb interactions. These results are an important step towards on-chip THz (opto)electronic applications.

The HELIPORT project aims to make the components or steps of the entire life cycle of a research project at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and the Helmholtz-Institute Jena (HIJ) discoverable, accessible, interoperable and reusable according to the FAIR principles. In particular, this data management solution deals with the entire lifecycle of research experiments, starting with the generation of the first digital objects, the workflows carried out and the actual publication of research results. For this purpose, a concept was developed that identifies the different systems involved and their connections. By integrating computational workflows (CWL and others), HELIPORT can automate calculations that work with metadata from different internal systems (application management, Labbook, GitLab, and further). This presentation will cover the first year of the project, the current status and the path taken so far in the life cycle of the project.

The multifactorial nature of Alzheimer’s disease necessitates the development of agents able to interfere with different relevant targets. A series of 22 tailored chromanones was conceptualized, synthesized and subjected to biological evaluation. We identified one representative bearing a linker-connected azepane moiety (compound 19) with balanced pharmacological properties. Compound 19 exhibited inhibitory activities against human acetyl-, butyrylcholinesterase and monoamine oxidase-B, as well as high affinity to both the 1 and 2 receptor. Our study provides a framework for the development of further chromanone-based multineurotarget agents.

Small actinium-225-labeled prostate-specific membrane antigen (PSMA)-targeted radioconjugates have been described for targeted alpha therapy of metastatic castration-resistant prostate cancer. Transient binding to serum albumin as a highly abundant, inherent transport protein represents a commonly applied strategy to modulate the tissue distribution profile of such low-molecular-weight radiotherapeutics and to enhance radioactivity uptake into tumor lesions with the ultimate objective of improved therapeutic outcome. Two ligands mcp-M-alb-PSMA and mcp-D-alb-PSMA were synthesized by combining a macropa-derived chelator with either one or two lysine-ureido-glutamate-based PSMA- and 4-(p-iodophenyl)butyrate albumin-binding entities using multistep peptide-coupling chemistry. Both compounds were labeled with [²²⁵Ac]Ac³⁺ under mild conditions and their reversible binding to serum albumin was analyzed by an ultrafiltration assay as well as microscale thermophoresis measurements. Saturation binding studies and clonogenic survival assays using PSMA-expressing LNCaP cells were performed to evaluate PSMA-mediated cell binding and to assess the cytotoxic potency of the novel radioconjugates [²²⁵Ac]Ac-mcp-M-alb-PSMA and [²²⁵Ac]Ac-mcp-D-alb-PSMA, respectively. Biodistributions of both ²²⁵Ac-radioconjugates were investigated using LNCaP tumor-bearing SCID mice.

A set of closure models for the Euler-Euler two-fluid framework that was previously established for bubbly flows, in a variety of different geometries comprising pipes, bubble columns and stirred tanks by Rzehak et al. 2017 and Shi et al. 2018, is applied here to a turbulent bubbly jet. The closure models for momentum exchange comprise drag-, lift-, wall force-, virtual mass force-, and turbulent dispersion -force. The turbulence in the liquid phase is calculated using the SST k-ω model with an additional source terms to consider the effects of bubble induced turbulence. The open-source Computational Fluid Dynamics (CFD) tool OpenFOAM is used to perform these simulations.
Experimental data for validation are obtained from the previous work performed by Sun et al. 1986. In the experiment, a bubbly jet was injected from a round nozzle of diameter (D=5.08mm) oriented in vertical upward direction into a still water tank. These data featured a comprehensive set of observables including mean phasic velocities, liquid turbulent kinetic energy, and gas fraction along profiles in axial and radial directions. Primarily, the value of the bubble sizes is reported from the experiment, and this was used as an input parameter to the closure relations in the CFD simulation. Sample results of the present simulations are reported in the following wok. Closer to the nozzle they, are in good agreement with the measurement data along the axial and radial directions. At larger distances from the nozzle region, however, deviations are observed in the gas fraction. In an attempt to improve the prediction ability of the model, most likely the dispersion effects due to bubble-induced turbulence should be considered at an increasing gas injection from the nozzle.

The Mu2e experiment, which is currently under construction at the Fermi National Accelerator Laboratory near Chicago, will search for the neutrinoless conversion of muons to electrons in the field of an aluminum nucleus with a sensitivity four orders of magnitude better than previous experiments. This process, which violates charged lepton flavor, is highly suppressed in the Standard Model and therefore undetectable. However, scenarios for physics beyond the Standard Model predict small but observable rates.

An extension of the Mu2e experiment making use of the PIP-II
accelerator upgrade at FNAL is currently studied. The Mu2e-II experiment aims
to improve the sensitivity by at least a factor of 10 compared to Mu2e.
To achieve this, it will utilize an 800 MeV proton beam with a beam power of 100 kW hitting a production target to produce the required amount of
pions and muons. This high beam intensity requires a substantially more
advanced target design with respect to Mu2e.

We will present simulation studies for several target designs. In particular,
we will compare results for energy deposition, radiation damage and particle
yields for both the targets and the surrounding materials using the MARS15,
FLUKA2021 and GEANT4 particle transport and reaction code packages.

The numerical simulation of gas-liquid flows is a challenging task, when dynamics of systems at industrial scales are considered. A significant contribution to this complexity arises due to the coexistence and interaction of different flow morphologies, such as bubbly and stratified flows. One of the phenomena is the entrainment of small gas bubbles into the liquid bulk at a large-scale gas-liquid interface in regions of high shear rates. In order to capture such phenomena and make reliable predictions, hybrid modelling approaches are used. One of those is the morphology adaptive multifield model developed by Meller et al. (2021), which combines an Euler-Euler method with an algebraic Volume-of-Fluid method for disperse and continuous gas structures, respectively. The interfacial drag coupling is adapted to the local grid resolution at the interface location (Meller et al., 2022). In such a modelling framework, morphology changes are realised by transfers between numerical phases, which are treated differently according to the basic simulation methodologies mentioned above.
In that sense, entrainment processes are characterised by multiple numerical aspects: 1) entrapping of large-scale gas structures, which subsequently disintegrate into smaller ones and 2) direct conversion of continuous towards disperse portions of gas due to processes taking place at sub-grid scales, which are described by dedicated entrainment models, such as the one of Ma et al. (2011). In this work, the individual effects as well as the interplay of the aforementioned processes are assessed and validated in comparison to experimental data of a liquid plunging jet (Chanson et al., 2004). This also considers the balance between the two numerical aspects mentioned above. The goal is to improve the reliability of predictions of gas entrainment with high as well as with low spatial resolution.

In the past decades, numerical simulation tools have developed much, becoming a reliable instrument for design and failure analysis of components in the field of aero- and hydrodynamics. The focus of research continuously shifts towards challenges that are more complex, such as multiphase flow problems. These flows typically involve strong dynamics, a number of complex physical phenomena as well as a large range of length and time scales, which are mainly connected to interfacial and turbulence structures. Such problems are particularly prevalent in the chemical and process industries. Typically, the development of tools for the numerical simulation focuses on a single morphology: a) disperse interfacial structures, which are not captured by the computational grid (Euler-Euler or Euler-Lagrange) or b) approaches resolving the interface between two different phases (volume-of-fluid or level-set). In many practical applications, the occurring flow morphology is unknown in advance and therefore, the most appropriate numerical model cannot be easily identified a-priori. Corresponding industrial facilities are flotation cells, refrigeration systems, biological and chemical reactors, distillation columns, swirl separators or centrifugal pumps, to name a few examples. In the past years, special hybrid simulation approaches have been developed to describe the aforementioned problems: 2-field methods considering blending between different morphologies, 4-field methods, where two phases represent the same physical phase, but with different morphology, drift-flux models based on the volume-of-fluid approach or methods blending between Euler-Euler and level-set models.
We present a 4-field approach, which is developed and validated at Helmholtz-Zentrum Dresden – Rossendorf as an add-on to the public domain library OpenFOAM. Central development criteria and goals are:
- Robust applicability to engineering problems at the industrial scale
- A unified set of conservation equations uniting different simulation methods without blending between them
- If the spatial resolution of the computational grid is high enough, the hybrid model should behave like a algebraic volume-of-fluid model
- In the case of coarse computational grids, disperse interfacial structures are modelled using the Euler-Euler method
- Phases forming large scale (resolved) interfaces and such that are dispersed within another phase, are treated as individual numerical phases

• Special mass transfer model formulations allow a phase to change morphology via transfer between different numerical phases
• Disperse phases can interact with large-scale interfaces by, e.g. bursting of bubbles or formation of foam

Understanding the stability limitations and defect formation mechanisms in 2D magnets is essen- tial for their utilization in spintronic and memory technologies. Here, we correlate defects in mono- to multilayer CrSBr with their structural and vibrational properties. We use resonant Raman scattering to reveal distinct vibrational defect signatures. In pristine CrSBr, we show that bromine atoms mediate vibrational interlayer coupling, allowing for distinguishing between surface and bulk defect modes. We show that environmental exposure causes drastic degradation in monolayers, with intralayer defects forming more readily in monolayers. Through deliberate ion irradiation, we tune the formation of defect modes, which we show are strongly polarized and resonantly enhanced, reflecting the quasi-1D electronic character of CrSBr. Overall, we present a structural and vibrational study of defective CrSBr, demonstrate the air stability above the monolayer threshold, and provide further insight into the quasi-1D physics present, creating crucial understanding for defect engineering of magnetic textures.

The dependence of froth flotation performance on various inter-related chemical, operational and instrumental components, makes optimizing a flotation system a very complex task. Computational Fluid Dynamics tools provide the means to study the flow inside a flotation cell by employing mathematical models that describe the interaction between the different phases of the system. The purpose of this work is to use Euler-Euler-Euler CFD simulations in OpenFOAM to validate a set of interfacial models to determine the hydrodynamics of a gas-solid-liquid flow. The combination of previously well validated baseline models for gas-liquid flows and solid-liquid flows is used for this purpose. The baseline combination includes drag, lift, wall, turbulent dispersion and virtual mass forces as well as bubble induced turbulence for gas-liquid interaction, and drag, lift, turbulent dispersion and virtual mass forces for solid-liquid interaction. Based on an extensive literature review of gas-solid-liquid experiments, the bubble column data of Rampure et al. are chosen for the numerical validation. Preliminary results show that the bubble diameter, which was not measured precisely, plays a significant role for the gas volume fraction distribution. Bubble diameter of 7 mm yields gas volume fraction profiles in agreement with the experimental data. The baseline combination yields higher particle suspension than indicated by the experimental data. This leads to a systematic study of the closure models. Choosing a model set similar to that of Rampure et al. improves the agreement of the solid distribution but deteriorates that of the gas distribution. It must be noted that, the high gas flow rate and high solid concentration likely require consideration of further aspects that are expected to have a significant effect on the flow. These may include a PIT model, a swarm corrector for the bubble and particle drag force, modifying the bubble drag force due to the existence of particles and vice versa, a solid pressure due to particle collisions and modifying the liquid viscosity due to the presence of particles. The study of the effect of these aspects is still on-going.

Bubble size and deformation are important factors for the closure models required in Euler-Euler simulations of bubbly flows. To properly simulate polydisperse bubbly flows where the bubble size spectrum may cover a range of several millimeters, several velocity groups with different sizes have to be considered. To this end, the theory for the particlecenter-averaged Euler-Euler model is generalized for the simulation with multiple bubble velocity groups. Furthermore, bubble deformation effects have been included in appropriate bubble force models. The particle-center-averaged Euler-Euler model provides additional freedom to consider the bubble shape during the conversion between the bubble number density and the gas volume fraction. Therefore, the theory is also generalized to consider an oblate ellipsoidal bubble shape in simulations. A bubbly pipe flow is used to validate the theory and to demonstrate the improvements of the proposed generalizations.

We investigate the frequency non-reciprocity in CoFeB/Ru/CoFeB synthetic antiferromagnets near the spin-flop transition region, where the magnetic moments in the two ferromagnetic layers are non-collinear. Using conventional Brillouin light scattering, we perform systematic measurements of the frequency non-reciprocity as a function of an external magnetic field. For the antiparallel alignment of the magnetic moments in the two layers, we observe a significant frequency non-reciprocity of up to a few GHz, which vanishes when the relative magnetization orientation switches into the parallel configuration at saturation. A non-monotonous dependence of the frequency non-reciprocity is found in the region where the system transitions from the antiparallel to the parallel orientation, with a maximum frequency shift around the spin-flop critical point. This non-trivial dependence of the non-reciprocity is attributed to the non-monotonous dependence of the dynamic dipolar interaction, which is the main factor that causes asymmetry in the dispersion relation. Furthermore, we found that the sign of the frequency shift changes even without switching the polarity of the bias field. These results show that one can precisely control the non-reciprocal propagation of spin waves via field-driven magnetization reorientation.

Gα proteins as part of heterotrimeric G proteins are molecular switches essential for GPCR mediated intracellular signaling. The role of the Gα subunits has been examined for decades with various guanine nucleotides to elucidate the activation mechanism and Gα protein-dependent signal transduction. Several approaches describe fluorescent ligands mimicking the GTP
function, yet lacking the efficient estimation of the proteins’ GTP binding activity and fraction of active protein. Herein, we report the development of a reliable fluorescence anisotropy-based method to determine the affinity of ligands at the GTP-binding site and to quantify the fraction of active Gαi1 protein. An advanced bacterial expression protocol was applied to produce active human Gαi1 protein, whose GTP binding capability was determined with novel fluorescently labeled guanine nucleotides acting as highaffinity Gαi1 binders compared to the commonly used BODIPY FL GTPγS. This study thus contributes a new method for future investigations of the characterization of Gαi and other Gα protein subunits, exploring their corresponding signal transduction systems and potential for biomedical applications.

Background and purpose: The relative biological effectiveness (RBE) varies along the treatment field.
However, in clinical practice, a constant RBE of 1.1 is assumed, which can result in undesirable side
effects. This study provides an accurate overview of current clinical practice for considering proton
RBE in Europe.
Materials and methods: A survey was devised and sent to all proton therapy centres in Europe that treat
patients. The online questionnaire consisted of 39 questions addressing various aspects of RBE consider-
ation in clinical practice, including treatment planning, patient follow-up and future demands.
Results: All 25 proton therapy centres responded. All centres prescribed a constant RBE of 1.1, but also
applied measures (except for one eye treatment centre) to counteract variable RBE effects such as avoid-
ing beams stopping inside or in front of an organ at risk and putting restrictions on the minimum number
and opening angle of incident beams for certain treatment sites. For the future, most centres (16) asked
for more retrospective or prospective outcome studies investigating the potential effect of the effect of a
variable RBE. To perform such studies, 18 centres asked for LET and RBE calculation and visualisation
tools developed by treatment planning system vendors.
Conclusion: All European proton centres are aware of RBE variability but comply with current guidelines
of prescribing a constant RBE. However, they actively mitigate uncertainty and risk of side effects result-
ing from increased RBE by applying measures and restrictions during treatment planning. To change RBE-
related clinical guidelines in the future more clinical data on RBE are explicitly demanded.

RDS data of models developed and reported for the article entitled "Integrated radiogenomics analyses allow for subtype classification and improved outcome prognosis of patients with locally advanced HNSCC". Software package version is also available in repository

Patients with locally advanced head and neck squamous cell carcinoma (HNSCC) may benefit from personalised treatment, requiring biomarkers that characterize the tumour and predict treatment response. We integrate pre-treatment CT radiomics and whole-transcriptome data from a multicentre retrospective cohort of 206 patients with locally advanced HNSCC treated with primary radiochemotherapy to classify tumour molecular subtypes based on radiomics, develop surrogate radiomics signatures for gene-based signatures related to different biological tumour characteristics and evaluate the potential of combining radiomics features with full-transcriptome data for the prediction of loco-regional control (LRC). Using end-to-end machine-learning, we developed and validated a model to classify tumours of the atypical subtype (AUC [95% confidence interval]: 0.69 [0.53-0.83]) based on CT imaging, observed that CT-based radiomics models have limited value as surrogates for six selected gene signatures (AUC<0.60), and showed that combining a radiomics signature with a transcriptomics signature consisting of two metagenes representing the hedgehog pathway and E2F transcriptional targets improves the prognostic value for LRC compared to both individual sources (validation C-index [95% confidence interval], combined: 0.63 [0.55-0.73] vs radiomics: 0.60 [0.50-0.71] and transcriptomics: 0.59 [0.49-0.69]). These results underline the potential of multi-omics analyses to generate reliable biomarkers for future application in personalized oncology.

Thanks to a rapid progress of high-power lasers since the birth of laser by T. H. Maiman in 1960, intense lasers have been developed mainly for studying the scientific feasibility of laser fusion. Inertial confinement fusion with an intense laser has attracted attention as a new future energy source after two oil crises in the 1970s and 1980s. From the beginning, the most challenging physics is known to be the hydrodynamic instability to realize the spherical implosion to achieve more than 1000 times the solid density. Many studies have been performed theoretically and experimentally on the hydrodynamic instability and resultant turbulent mixing of compressible fluids. During such activities in the laboratory, the explosion of supernova SN1987A was observed in the sky on 23 February 1987. The X-ray satellites have revealed that the hydrodynamic instability is a key issue to understand the physics of supernova explosion. After collaboration between laser plasma researchers and astrophysicists, the laboratory astrophysics with intense lasers was proposed and promoted around the end of the 1990s. The original subject was mainly related to hydrodynamic instabilities. However, after two decades of laboratory astrophysics research, we can now find a diversity of research topics. It has been demonstrated theoretically and experimentally that a variety of nonlinear physics of collisionless plasmas can be studied in laser ablation plasmas in the last decade. In the present paper, we shed light on the recent 10 topics studied intensively in laboratory experiments. A brief review is given by citing recent papers. Then, modeling cosmic-ray acceleration with lasers is reviewed in a following session as a special topic to be the future main topic in laboratory astrophysics research.

In recent research concerning zinc dissolution studies in boric acid
electrolytes, it was shown that moderate variations of the fluid temperatures
or the boric acid concentration only cause small changes (<10%) in resulting
initial zinc corrosion rates. A stronger dependency was found, however, on the
fluid flow. Thus, a series of electrochemical measurements were carried out
using a rotating disc electrode (zinc) in boric acid electrolytes for a better
understanding of influencing parameters on the zinc corrosion rates. The main
results of these electrochemical polarization experiments (e.g., Tafel plots)
showed similar dependencies of the zinc corrosion rates as described in the
aforementioned zinc dissolution experiments. The zinc corrosion process
strongly depends on the mass transfer limitation of the dissolved oxygen to the
zinc surface (cathodic process). Increased rotation speeds (higher flow rates)
lead to extensively enhanced current densities (corrosion rates) and the
extrapolation to infinite high rotation speeds (Levich extrapolation) was used
to describe the corresponding corrosion process without transfer limitations.

Rare earth elements (REE) have become critical components in science and industry. Their anthropogenic release into the environment and entry into the food chain poses a risk for the health of living beings. Therefore, a comprehensive understanding of the transfer and migration behaviour, the resulting localization and molecular characterization of REE in biological systems is crucial for a reasonable risk assessment and remediation strategies.

Modeling warm dense matter is relevant for various applications including the interior of gas giants and exoplanets, inertial confinement fusion, and ablation of metals. Ongoing and upcoming experimental campaigns in photon sources around the globe rely on numerical simulations which are accurate on the level of electronic structures. In that regard, density functional theory molecular dynamics (DFT-MD) simulations have been widely used to compute dynamical and thermodynamical properties of warm dense matter. However, two challenges impede further progress: (1) DFT-MD becomes computational infeasible with increasing temperature (2) finite-size effects render many computational observables inaccurate, because DFT-MD is limited to a few hundred atoms on current HPC platforms. Recently, molecular dynamics simulations using machine learning-based interatomic potentials (ML-IAP) could overcome these computational limitations. Here, we propose a method to construct ML-IAPs from DFT data based on SNAP descriptors [1]. We demonstrate our workflow for aluminum. In particular, we investigate the transferability of ML-IAPs over a large range of temperatures and pressures, which currently is a topic of active research.

References:

[1] A. P. Thompson, L. P. Swiler, C. R. Trott, S. M. Foiles, and G. J. Tucker, Journal of
Computational Physics, 285, 316-330, 2015.

Modeling warm dense matter is relevant for various applications including the interior of gas giants and exoplanets, inertial confinement fusion, and ablation of metals. Ongoing and upcoming experimental campaigns in photon sources around the globe rely on numerical simulations which are accurate on the level of electronic structures. In that regard, density functional theory molecular dynamics (DFT-MD) simulations [1] have been widely used to compute dynamical and thermodynamical properties of warm dense matter. However, two challenges impede further progress: (1) DFT-MD becomes computational infeasible with increasing temperature (2) finite-size effects render many computational observables
inaccurate, because DFT-MD is limited to a few hundred atoms on current HPC platforms. Recently, molecular dynamics simulations using machine learning-based interatomic potentials (ML-IAP) could overcome these computational limitations. Here, we propose a method to construct ML-IAPs from DFT data based on SNAP descriptors [2]. We present our results for aluminum. In particular, we investigate the transferability of ML-IAPs over a large range of temperatures and pressures, which currently is a topic of active research.

References:

[1] G. Kresse and J. Hafner, Phys. Rev. B 47, 558 (1993).
[2] A. P. Thompson, L. P. Swiler, C. R. Trott, S. M. Foiles, and G. J. Tucker, Journal of Computational Physics, 285, 316-330, 2015.

Flash lamp annealing (FLA) is a non-equilibrium annealing method on the sub-second time scale which excellently meets the requirements of thin film processing. FLA has already been used in microelectronics, mostly after ion implantation, to activate dopants, to recrystallize amorphous semiconductor layers, and to anneal out defects. Another field of application is the formation of silicide and germanide materials for contact fabrication. However, in the last twenty years, FLA has opened up new areas of application like thin films on glass, sensors, printed electronics, flexible electronics, energy materials etc. For two years, the Helmholtz Innovation Blitzlab aims to transfer this technology to industry and application-related research.
After a short introduction, a brief overview of FLA is given, discussing the advantages and challenges of this technology. The main part displays various examples from literature and from our own research, in which FLA has been applied to semiconductors, namely to Si, Ge and GaN. In detail, the doping close or even above the solubility limit of dopants, the crystallization of Ge during FLA, the formation of NiGe for contacts, and p-type doping in GaN are addressed.

Two modes of laser annealing, namely, Continuous Wave (CW) and Pulsed Wave (PW) mode, are used for modifying the magnetic properties of perpendicular magnetic anisotropy (PMA) multilayers in a controlled manner. For this we compare two types of samples - a PMA (Co/Pt)₁₀ multilayer and an antiferromagnetically interlayer exchange coupled PMA (Co/Pt)₄/Co/Ir/(Co/Pt)₅ multilayer. Room temperature hysteresis loops using polar MOKE magnetometry are measured for the different laser annealing modes. Thus, a relationship between the applied laser parameters and the magnetic properties is extracted, which provides an opportunity to alter magnetic properties of PMA multilayer systems locally with high spatial resolution on demand.

Co/Pt multilayers (MLs) are standard systems for perpendicular anisotropy layered thin films. The use of a specific underlayer, sometimes in combination with additional, very thin adhesion layers, is a common practice to define a crystalline texture for the ML on amorphous substrates. In addition, the sputter gas pressure during deposition can be used to tune the lateral heterogeneity and laminate order, which strongly affect the magnetic behavior of the system. However, the precise interplay between adhesion and sputter gas pressure, especially for the seed layer, is often neglected.

In this context, we will discuss the impact of the underlayers on the structural and magnetic properties of the Co/Pt ML system. We will emphasize the influence of an adhesion layer on the whole system and combine this with a systematic and separate variation of the sputter deposition pressure of Pt seed and Co/Pt ML. Carefully tuning these parameters enables us to exert a high degree of control on the structure of these systems, with characteristics ranging from continuous thin films to isolated grain structures.

Tailoring the magnetization dynamics and anisotropy in ferromagnetic thin films by different seed layers is of great fundamental and practical importance, e.g., different seed layer materials lead to different microstructure and magnetocrystalline anisotropy energy. We have used Ta and Pt as seed layers for thin Co films and studied their broadband ferromagnetic resonance (FMR) in out-of-plane saturation as a function of Co thickness and determined the respective perpendicular magnetic anisotropy. For Ta seeds, the magnetic anisotropy decreases and shows an inverse thickness dependence. In contrast for Pt seeds the magnetic anisotropy is no longer monotonous with thickness, but shows an initial thickness dependent decrease with a distinct minimum and subsequently a steady increase again. XRD measurements show that for Pt seeds, the Co develops a well-defined hcp texture with a thickness dependent strain relaxation. As a result of this structural evolution for Co on Pt seeds our FMR measurements reveal a strong anisotropy gradient in growth direction for this system.

Ferromagnetism can be induced in non-ferromagnetic alloys such as B2 Fe₆₀Al₄₀[1] and B2 Fe₅₀Rh₅₀[2] through lattice disordering. Here we study a magnetostructural transition in Fe₆₀V₄₀ thin films using ion-irradiation. We show that the as-grown films possess an M_S of 17 kA/m and irradiation with 25 keV Ne⁺-ions at a fluence of 5 x 10¹⁵ions/cm² leads to an increase of M_S to ∼ 750 kA/m. A structural short-range order is observed in the as-grown films that transforms to A2 phase via ion-irradiation. Mössbauer spectroscopy and Ferromagnetic Resonance have been applied to track the variation of local magnetic ordering and dynamic behaviour respectively.

Financial support by DFG grants BA 5656/1-2 and WE 2623/14-2 is acknowledged.

[1]Ehrler, J.et al., New J. Phys.,22,073004(2020)

[2]Eggert, B.et al., RSC Adv.,10,14386(2020)

Nonvolatile and energy-efficient spin-based technologies call for new prospects to realize computation and communication devices that are able to operate at terahertz (THz) frequencies. In particular, the coupling of electro-magnetic radiation to a spin system is a general requirement for future communication units and sensors. Here we propose a layered metallic system, based on a ferromagnetic film sandwiched in between two heavy metals that allows a highly effective coupling of millimeter wavelength THz light to nanometer-wavelength magnon modes. Using single-cycle broadband THz radiation we are able to excite spin-wave modes with a frequency of up to 0.6 THz and a wavelength as short as 6 nm. Our experimental and theoretical studies demonstrate that the coupling originates solely from interfacial spin-orbit torques. These results are of general applicability to magnetic multilayered structures, and offer the perspective of coherent THz excitation of exchange-dominated nanoscopic magnon modes.

Perpendicular anisotropy thin film systems are well known for their highly periodic magnetic stripe domains. Here we study [Co(3.0 nm)/Pt(0.6 nm)]_X multilayers in the regime of transitional in-plane to out-of-plane anisotropy. For this we vary the number of repeats X in order to tune the remanent state from purely in-plane (IP) via tilted stripe domains (tilted), i.e. with significant out-of plane as well as in-plane magnetization component, to fully out-of-plane stripe domains (OOP). Vibrating Sample Magnetometry and Magnetic Force Microscopy are used to investigate three characteristic samples with X = 6,11 and 22, which represent the three above mentioned remanent states, respectively. In contrast to fully in-plane or fully out-of-plane systems experimental data and corresponding micromagnetic simulation of the tilted magnetization regime (X=11) reveals fully reversible field regions as well as distinct points of irreversibility during an external field sweep. This collective reversal behavior seems at first sight somewhat counter intuitive for a macroscopic system and has qualitative similarities with microscopic systems, such as the Stoner Wohlfarth particle and the vortex reversal in an in-plane magnetized disk, which both show as well distinct points of irreversibility.

Herausforderungen bei der TEM-Probenpräparation von neuartigen Elektroden-Materialen für Li-Ionen-Batterien

Catalysts can be successfully prepared by a simple electrochemical process. Their surface composition distinguishes catalytic activity toward hydrogen and oxygen evolution reactions. In this work, uniform Co-Ni cones were synthesized using the onestep method from an electrolyte containing a crystal modifier. Electrodeposited layers were oxidized and/or reduced in the furnace at 100°C. Freshly electrodeposited coating was stored in air atmosphere for seven days. This results in an oxide layer forming on the surface of the catalyst. Changes in the surface composition, confirmed by the XPS method, strongly influenced the wettability, catalytic performance, and size of evolved hydrogen bubbles. The conical Co-Ni surface oxidized in a controlled way possesses the best catalytic activity towards hydrogen and oxygen evolution. Conversely, the spontaneously formed oxide layer decreases the catalytic performance in mentioned reactions compared with the fresh sample. The proper storage of synthesized samples is essential due to their desired catalytic applications. Proposed controlled oxidation can be an accessible way to increase nanomaterials catalytic performance.

The spatial magnetization texture of a cylindrical nanowire has been determined by Transmission X-ray Microscopy (TXM) and X-ray magnetic circular dichroism (XMCD). For this purpose, nanowires with designed geometry, consisting of CoNi/Ni periodic segments, have been grown by designed electrodeposition into alumina templates. Experimental data allows one to conclude the presence of mono- and trivortex magnetic domains in CoNi segments but, unusually, these states are characterized by an asymmetric XMCD contrast across the nanowire’s section. Micromagnetic modelling shows non-trivial three-dimensional structures with ellipsoidal vortex cores and non-axially symmetric magnetization along the nanowire direction. The modelled TXM contrast of micromagnetic structures allows to correlate the experimental asymmetric XMCD contrast to the easy axis direction of the uniaxial magnetocrystalline anisotropy.

Contrary to the common belief that the light-induced halide ion segregation in a mixed halide alloy occurs within the illuminated area, we find that the Br ions released by light are expelled from the illuminated area, which generates a macro/mesoscopic size anion ring surrounding the illuminated area, exhibiting a photoluminescence ring. This intriguing phenomenon can be explained as resulting from two counter-balancing effects: the outward diffusion of the light-induced free Br ions and the Coulombic force between the anion deficit and surplus region. Right after removing the illumination, the macro/mesoscopic scale ion displacement results in a built-in voltage of about 0.4 V between the ring and the center. Then, the displaced anions return to the illuminated area, and the restoring force leads to a damped ultra-low-frequency oscillatory ion motion, with a period of about 20–30 h and lasting over 100 h. This finding may be the first observation of an ionic plasma oscillation in solids. Our understanding and controlling the “ion segregation” demonstrate that it is possible to turn this commonly viewed “adverse phenomenon” into novel electronic applications, such as ionic patterning, self-destructive memory, and energy storage.

Windsichten ist in der Zementindustrie ein seit Jahrzehnten bekanntes Verfahren zum Klassieren im Bereich 0,01-1,0 mm. Zusätzlich kann in entsprechenden Trockenmahlkreisläufen in Kombination mit Maschinen wie Hochdruckmahlwalzen (HPGR) der Energieverbrauch im Vergleich zu Nassanwendungen deutlich reduziert werden. Diese trocken arbeitenden Systeme sind in der Mineralaufbereitung noch nicht Stand der Technik, aber erste Prototypen wurden installiert und eine zunehmende Anzahl von Projekten beginnt, diese Alternative näher zu untersuchen.
Eine Herausforderung in diesem Bereich ist die mineralische Zusammensetzung von Erzen, die in Bezug auf Dichte und Größe eine weitaus größere Vielfalt aufweisen als Zement. Partikel mit hoher Dichte, wie z. B. eisenhaltige Partikel, haben bei gleicher Größe höhere Sinkgeschwindigkeiten als Silikatpartikel mit niedrigerer Dichte. Der vorliegende Beitrag untersucht, wie dieser Effekt bewertet werden kann. Dazu wurde eine quantitative Methode auf Basis der Mineral Liberation Analysis (MLA) entwickelt, um zweidimensionale Trennfunktionen zu berechnen. Zusätzliche statistische Analysen ermöglichen es, die Wechselwirkung von Dichte und Größe isoliert voneinander zu betrachten und so, entsprechende Effekte bei der Dimensionierung von Prozessanlagen zu berücksichtigen. In dem Beitrag werden die Methode und ausgewählte Ergebnisse für ein Eisenerz vorgestellt.

Modeling warm dense matter is relevant for various applications including the interior of gas giants and exoplanets, inertial confinement fusion, and ablation of metals. Ongoing and upcoming experimental campaigns in photon sources around the globe rely on numerical simulations which are accurate on the level of electronic structures. In that regard, density functional theory molecular dynamics (DFT-MD) simulations [1] have been widely used to compute the dynamical and thermodynamical properties of warm dense matter. However, two challenges impede further progress: (1) DFT-MD becomes computationally infeasible with increasing temperature (2) finite-size effects render many computational observables inaccurate, because DFT-MD is limited to a few hundred atoms on current HPC platforms. Recently, molecular dynamics simulations using machine learning-based interatomic potentials (ML-IAP) could overcome these computational limitations. Here, we propose a method to construct ML-IAPs from DFT data based on SNAP descriptors [2]. We present our results for aluminum. In particular, we investigate the transferability of ML-IAPs over a large range of temperatures (1000 to 100000 K) and pressures (ambient to 800 GPa), which currently is a topic of active research. To test the transferability of the SNAP potential, we calculate thermal conductivity, viscosity, diffusion coefficient, and sound velocity in and out of the data training range.

References:

[1]. G. Kresse and J. Hafner, Phys. Rev. B 47, 558 (1993).
[2]. A. P. Thompson, L. P. Swiler, C. R. Trott, S. M. Foiles, and G. J. Tucker, J. Comput. Phys., 285, 316-330, 2015.

Single bubble rising in the close vicinity of a vertical wall is one of the focuses in the field of gas-liquid two-phase flow. In this work, three-dimensional direct numerical simulation based on volume of fluid (VOF) and adaptive mesh refinement method is performed to investigate the bubble rising and wake structures near a vertical wall. The bubble migration trajectory, deformation, velocity and wake structures were analyzed under various Galileo numbers and initial wall distances. Bubbles with a Galileo number of 8.8 significantly migrate away from the wall, which is driven by the repulsive force as a result of the suppression of the vortex diffusion on the bubble surface. As the Galileo number increases, the asymmetry of the shedding vortex tends to play a vital role on the repulsive force, which is exacerbated by the presence of the vertical wall. A periodic shedding of the vortex appears behind the bubble when the Galileo number reaches at 95. Meanwhile, the bubble trajectory changes from rectilinear to spiral along with a periodic oscillation. Due to the interaction between the vertical wall and the bubble wake, a transition from a rectilinear rising path to a spiral rising path is more likely to occur compared to that without a vertical wall. The presence of a vertical wall contributes to bubble-rising oscillations. A decrease of the bubble terminal velocity due to viscous effect near the vertical wall is observed for bubbles at low Galileo numbers. However, the viscous effect is less pronounced as the Galileo number increases.

Understanding the electronic transport properties of iron under high temperatures and pressures is essential for constraining geophysical processes. The difficulty of reliably measuring these properties calls for sophisticated theoretical methods that can support diagnostics. We present results of the electrical conductivity within the pressure and temperature ranges found in Earth's core by simulating microscopic Ohm's law using time-dependent density functional theory.

consensus and controversial aspects of CT innovation in RT

This work investigates how knock-on displacements influence fluctuation electron microscopy (FEM) experiments. FEM experiments were conducted on amorphous silicon, formed by self-ion implantation, in a transmission electron microscope at 300 kV and 60 kV at various electron doses, two different binnings and with two different cameras, a CCD and a CMOS one. Furthermore, energy filtering has been utilized in one case. Energy filtering greatly enhances the FEM data by removing the inelastic background intensity, leading to an improved speckle contrast. The CMOS camera yields a slightly larger normalized variance than the CCD at an identical electron dose and appears more prone to noise at low electron counts. Beam-induced atomic displacements affect the 300 kV FEM data, leading to a continuous suppression of the normalized variance with increasing electron dose. Such displacements are considerably reduced for 60 kV experiments since the primary electron’s maximum energy transfer to an atom is less than the displacement threshold energy of amorphous silicon. The results show that the variance suppression due to knock-on displacements can be controlled in two ways: Either by minimizing the electron dose to the sample or by conducting the experiment at a lower acceleration voltage.

Interactions of heavy metals with charged mineral surfaces control their mobility in the environment. Here, we investigate the adsorption of Y(III) onto the orthoclase (001) basal plane, the former as a representative of rare earth elements and an analogue of trivalent actinides and the latter as a representative of naturally abundant K-feldspar minerals. We apply in-situ high-resolution X-ray reflectivity to determine the sorption capacity and molecular distribution of adsorbed Y species as a function of Y3+ concentration and pH. We observe an inner-sphere (IS) sorption complex at a distance of ~1.5 Å from the surface and an outer-sphere (OS) complex at 3–4 Å. Based on the adsorption height of the IS complex a bidentate, binuclear binding mode, in which Y3+ binds to two terminal oxygens seems most plausible. The total Y coverages of IS and OS species are max. ~1.3 Y3+/AUC for all Y concentrations (AUC: area of the unit cell = 111.4 Ų), which is in the expected range based on the estimated surface charge of orthoclase (001).

Silicon carbide (SiC) is a suitable candidate for Micro- and Nanoelectromechanical systems due to its superior mechanical properties. We would like to use it as a quantum sensor to sense small magnetic fields. It can be achieved by coupling a spin associated silicon vacancy (V_Si) in 4H-SiC with a mechanical mode of a resonator. Spin-mechanical resonance is observed when resonance frequency from V_Si matches resonance frequency of a mechanical mode.
In the initial experiments, we focus on the material modification by helium (He+) ion broad beam implantation on a strained resonator based on 3C-SiC implanted with high fluence of (1*10^14 /cm^2) and low fluence (1*10^12 /cm^2) at 14 keV. The change in resonance frequency and quality factors as a function of fluence is studied. We also show the effect on stress and higher modes of the nanomechanical resonators.

Cerebral perfusion models were found to be promising research tools to predict the impact of acute ischaemic stroke and related treatments on cerebral blood flow (CBF) linked to patients’ functional outcome. To provide insights relevant to clinical trials, perfusion simulations need to become suitable for group-level investigations, but computational studies to date have been limited to a few patient-specific cases. This study set out to overcome issues related to automated parameter inference, that restrict the sample size of perfusion simulations, by integrating neuroimaging data. Seventy-five brain models were generated using measurements from a cohort of 75 healthy elderly individuals to model resting-state CBF distributions. Computational perfusion model geometries were adjusted using healthy reference subjects’ T1-weighted MRI. Haemodynamic model parameters were determined from CBF measurements corresponding to arterial spin labelling perfusion MRI. Thereafter, perfusion simulations were conducted for 150 acute ischaemic stroke cases by simulating an occlusion and cessation of blood flow in the left and right middle cerebral arteries. The anatomical (geometrical) fitness of the brain models was evaluated by comparing the simulated grey and white matter (GM and WM) volumes to measurements in healthy reference subjects. Statistically significant, strong positive correlations were found in both cases (GM: Pearson’s r 0.74, P-value< 0.001; WM: Pearson’s r 0.84, P-value< 0.001). Haemodynamic parameter tuning was verified by comparing total volumetric blood flow rate to the brain in reference subjects and simulations resulting in Pearson’s r 0.89, and P-value< 0.001. In acute ischaemic stroke cases, the simulated infarct volume using a perfusion-based proxy was 197±25 ml. Computational results showed excellent agreement with anatomical and haemodynamic literature data corresponding to T1-weighted, T2-weighted, and phase-contrast MRI measurements both in healthy scenarios and in acute ischaemic stroke cases. Simulation results represented solely worst-case stroke scenarios with large infarcts because compensatory mechanisms, e.g. collaterals, were neglected. The established computational brain model generation framework provides a foundation for population-level cerebral perfusion simulations and for in silico clinical stroke trials which could assist in medical device and drug development.

Regulatory Requirements for the Translation of Radiopharmaceuticals

The ELBE accelerator at Helmholtz-Zentrum Dresden-Rossendorf has been commissioned in 2001 using klystron power amplifiers. In the course of a major machine upgrade in 2012, solid state power amplifiers have been installed to drive the superconducting cavities and to increase the maximum beam current to 1.6 mA. The talk will introduce the high power radio frequency system of the continuous wave (CW) accelerator ELBE, wrap-up the operational experience and will give an outlook to the potential successor of machine called DALI.

The fundamental laws necessary for the mathematical treatment of a large part of physics and the whole of chemistry are thus completely known, and the difficulty lies only in the fact that application of these laws leads to equations that are too complex to be solved." Nearly a century has passed, yet the famous quote by Paul Dirac still gets to the heart of many research fields within theoretical physics, quantum chemistry, material science, etc. In this talk, I will show how we can use cutting-edge numerical methods on modern high-performance computing systems to effectively overcome these limitations in many cases. In this way, we get unprecedented insights into quantum many-body systems on the nanoscale going all the way from ultracold atoms like superfluid helium to warm dense matter that occurs within planetary interiors and thermonuclear fusion applications.

The study of matter under extreme densities and temperatures as they occur e.g. in astrophysical objects and nuclear fusion applications has emerged as one of the most active frontiers in physics, material science, and related disciplines. In this context, a key quantity is given by the dynamic structure factor S(q,ω), which is probed in scattering experiments -- the most widely used method of diagnostics at these extreme conditions. In addition to its crucial importance for the study of warm dense matter, the modeling of such dynamic properties of correlated quantum many-body systems constitutes one of the most fundamental theoretical challenges of our time. Here we report a hitherto unexplained roton feature in S(q,ω) of the warm dense electron gas [1], and introduce a microscopic explanation in terms of a new electronic pair alignment model [2]. This new paradigm will be highly important for the understanding of warm dense matter, and has a direct impact on the interpretation of scattering experiments. Moreover, we expect our results to give unprecedented insights into the dynamics of a number of correlated quantum many-body systems such as ultracold helium, dipolar supersolids, and bilayer heterostructures.

[1] T. Dornheim, S. Groth, J. Vorberger, and M. Bonitz, Phys. Rev. Lett. 121, 255001 (2018)
[2] T. Dornheim, Zh. Moldabekov, J. Vorberger, H. Kählert, and M. Bonitz, arXiv:2203.12288

A set of GaN layers prepared by metalorganic vapor phase epitaxy under different technological conditions (growth temperature carrier gas type and Ga precursor) were investigated by varia-ble energy positron annihilation spectroscopy (VEPAS) to find a link between technological conditions, GaN layer properties and the concentration of galium vacancies (VGa). Different cor-relations between technological parameters and VGa concentration were observed for layers grown from triethyl gallium (TEGa) and trimethyl gallium (TMGa) precursors. In case of TEGa formation of VGa was significantly influenced by type of reactor atmosphere (N2 or H2), while no similar behaviour was observed for growth from TMGa. Formation of VGa was suppressed with increasing temperature for the growth from TEGa. On the contrary, enhancement of VGa concen-tration was observed for growth from TMGa with cluster formation for the highest temperature of 1100°C. From the correlation of photoluminescence results with VGa concentration determined by VEPAS it can be concluded, that yellow band in GaN is likely not connected with VGa and ad-ditionally, increased VGa concentration enhances excitonic luminescence. Probable explanation is that VGa prevents formation of some other highly efficient nonradiative defects. Possible types of such defects are suggested.

Warm dense matter (WDM)---an extreme state that is characterized by extreme densities and temperatures---has emerged as one of the most active frontiers in plasma physics and material science. In nature, WDM occurs in astrophysical objects such as giant planet interiors and brown dwarfs. In addition, WDM is highly important for cutting-edge technological applications such as inertial confinement fusion and the discovery of novel materials.
In the laboratory, WDM is studied experimentally in large facilities around the globe, and new techniques have facilitated unprecedented insights into exciting phenomena like the formation of nano diamonds at planetary interior conditions [1]. Yet, the interpretation of these experiments requires a reliable diagnostics based on accurate theoretical modeling, which is a notoriously difficult task [2].
In this talk, I give an overview of recent ground-breaking developments in this field [3,4], which will allow for the first time to rigorously treat the intricate interplay of Coulomb coupling with thermal excitations and quantum degeneracy effects. Moreover, I show how cutting-edge quantum Monte Carlo simulation techniques will help to decisively improve density functional theory (DFT) simulations of WDM, thereby opening up unprecedented perspectives and new paradigms such as the experimental and theoretical study of nonlinear effects [5,6]. Finally, I will present a new idea to extract the exact temperature from an X-ray Thomson scattering experiment without any models or simulations [7].

[1] D. Kraus et al., Nature Astronomy 1, 606-611 (2017)
[2] M. Bonitz et al., Physics of Plasmas 27, 042710 (2020)
[3] T. Dornheim et al., Physics Reports 744, 1-86 (2018)
[4] T. Dornheim et al., Physical Review Letters 121, 255001 (2018)
[5] T. Dornheim et al., Physical Review Letters 125, 085001 (2020)
[6] Zh. Moldabekov et al., Journal of Chemical Theory and Computation 18, 2900-2912 (2022)
[7] T. Dornheim et al., arXiv:2206.12805

Background:

A clinical study regarding the potential of range verification in proton therapy by prompt gamma imaging (PGI) is carried out at our institution. Manual interpretation of the detected spot-wise range shift information is time-consuming, highly complex, and therefore not feasible in a broad routine application.

Purpose:

Here, we present an approach to automatically detect and classify treatment deviations in realistically simulated PGI data for head and neck cancer (HNC) treatments using convolutional neural networks (CNNs) and conventional machine learning (ML) approaches.

Methods:

For 12 HNC patients and one anthropomorphic head phantom (n=13), pencil beam scanning (PBS) treatment plans were generated and one field per plan was assumed to be monitored with the IBA slit camera. In total, 386 scenarios resembling different relevant or non-relevant treatment deviations were simulated on planning and control CTs and manually classified into 7 classes: non-relevant changes (NR) and relevant changes (RE) triggering treatment intervention due to range prediction errors (±RP), setup errors in beam direction (±SE), anatomical changes (AC), or a combination of such errors (CB). PBS spots with reliable PGI information were considered with their nominal Bragg peak position for the generation of two 3D spatial maps of 16⨯16⨯16 voxels containing PGI-determined range shift and proton number information. Three complexity levels of simulated PGI data were investigated: (I) optimal PGI data, (II) realistic PGI data with simulated Poisson noise based on the locally delivered proton number, and (III) realistic PGI data with an additional positioning uncertainty of the slit camera following an experimentally determined distribution.
For each complexity level, 3D-CNNs were trained on a data subset (n=9) using patient-wise leave-one-out cross-validation and tested on an independent test cohort (n=4). Both the binary task of detecting RE and the multi-class task of classifying the underlying error source were investigated. Similarly, four different conventional ML classifiers (logistic regression, multi-layer perceptron, random forest, support vector machine) were trained using five previously established handcrafted features extracted from the PGI data and used for performance comparison.

Results:

On the test data, the CNN ensemble achieved a binary accuracy of 0.95, 0.96, and 0.93 and a multi-class accuracy of 0.83, 0.81, and 0.76 for the complexity levels (I), (II), and (III), respectively. In the case of binary classification, the CNN ensemble detected treatment deviations in the most realistic scenario with a sensitivity of 0.95 and a specificity of 0.88. The best performing ML classifiers showed a similar test performance.

Conclusions:

This study demonstrates that CNNs can reliably detect relevant changes in realistically simulated PGI data and classify most of the underlying sources of treatment deviations. The CNNs extracted meaningful features from the PGI data with a performance comparable to ML classifiers trained on previously established handcrafted features. These results highlight the potential of a reliable, automatic interpretation of PGI data for treatment verification, which is highly desired for broad clinical application and a prerequisite for the inclusion of PGI in an automated feedback loop for online adaptive proton therapy.

We provide a novel high-order integration scheme crossing the limitations of established curved triangle techniques, that can be applied to a broad class of surfaces, providing a high-order approximation of the integrand and the geometry of the surface. This approach relies on recent results of multivariate interpolation which enable a global polynomial level set to be used to implicitly represent a broad class of closed surfaces.

Artificial intelligence (AI) solutions that automatically extract information from digital histology images have shown great promise for improving pathological diagnosis. Prior to routine use, it is important to evaluate their predictive performance and obtain regulatory approval. This assessment requires appropriate test datasets. However, compiling such datasets is challenging and specific recommendations are missing. A committee of various stakeholders, including commercial AI developers, pathologists, and researchers, discussed key aspects and conducted extensive literature reviews on test datasets in pathology. Here, we summarize the results and derive general recommendations on compiling test datasets. We address several questions: Which and how many images are needed? How to deal with low-prevalence subsets? How can potential bias be detected? How should datasets be reported? What are the regulatory requirements in different countries? The recommendations are intended to help AI developers demonstrate the utility of their products and to help pathologists and regulatory agencies verify reported performance measures. Further research is needed to formulate criteria for sufficiently representative test datasets so that AI solutions can operate with less user intervention and better support diagnostic workflows in the future.

The experimental investigation of matter under extreme densities and temperatures as they occur for example in astrophysical objects and nuclear fusion applications constitutes one of the most active frontiers at the interface of material science, plasma physics, and engineering. The central obstacle is given by the rigorous interpretation of the experimental results, as even the diagnosis of basic parameters like the temperature T is rendered highly difficult by the extreme conditions. In this work, we present a simple, approximation-free method to extract the temperature of arbitrarily complex materials from scattering experiments, without the need for any simulations or an explicit deconvolution. This new paradigm can be readily implemented at modern facilities and corresponding experiments will have a profound impact on our understanding of warm dense matter and beyond, and open up a gamut of appealing possibilities in the context of thermonuclear fusion, laboratory astrophysics, and related disciplines.

The accurate theoretical description of the dynamic properties of correlated quantum many-body systems such as the dynamic structure factor S(q,ω) constitutes an important task in many fields. Unfortunately, highly accurate quantum Monte Carlo methods are usually restricted to the imaginary time domain, and the analytic continuation of the imaginary time density--density correlation function F(q,τ) to real frequencies is a notoriously hard problem. In this work, we argue that no such analytic continuation is required as F(q,τ) contains, by definition, the same physical information as S(q,ω), only in an unfamiliar representation. Specifically, we show how we can directly extract key information such as the temperature or quasi-particle excitation energies from the τ-domain, which is highly relevant for equation-of-state measurements of matter under extreme conditions. As a practical example, we consider \emph{ab initio} path integral Monte Carlo results for the uniform electron gas (UEG), and demonstrate that even nontrivial processes such as the \emph{roton feature} of the UEG at low density straightforwardly manifest in F(q,τ). In fact, directly working in the τ-domain is advantageous for many reasons and holds the enticing promise for unprecedented agreement between theory and experiment.

The electronic exchange-correlation (XC) kernel constitutes a fundamental input for the estimation of a gamut of material properties such as the dielectric characteristics, the thermal and electrical conductivity, the construction of effective potentials, or the response to an external perturbation. In practice, no reliable method has been known that allows to compute the kernel of real materials. In this work, we overcome this long-standing limitation by introducing a new, formally exact methodology for the computation of the static XC kernel of arbitrary materials exclusively within the framework of density functional theory (DFT) -- no external input apart from the usual XC-functional is required. As a first practical demonstration of the utility and flexibility of our methodology, we compare our new results with exact quantum Monte Carlo (QMC) data for the archetypical uniform electron gas model at both ambient and warm dense matter conditions. This gives us unprecedented insights into the performance of different XC-functionals, and has important implications for the development of new functionals that are designed for the application at extreme temperatures. In addition, we obtain new DFT results for the XC kernel of warm dense hydrogen as it occurs in fusion applications and astrophysical objects such as planetary interiors. The observed excellent agreement to the recent QMC results by Böhme \emph{et al.}~[Phys.~Rev.~Lett.~\textbf{129}, 066402 (2022)] clearly demonstrates that our framework is capable to even capture nontrivial effects such as XC-induced isotropy breaking in the density response of hydrogen at large wave numbers. Our method can easily be applied using standard DFT codes and will open up new avenues for the computation of the properties of real materials.

As a part of my graduation internship in engineering and master’s degree, I work in the Helmholtz Zentrum Dresden-Rosseendorf institute for an internship of 6-months. I am a part of a team consisting of my supervisor, Dr. Sebastian Unger and a PhD student, Mrs. Malini Bangalore. The latter studies a thermal energy storage (TES). The storage would store electricity as heat from renewable energy sources when the supply in electricity is higher than the demand. In case of residual load demand, the stored thermal energy would be released to a power cycle and supply the electrical grid. Therefore, a heat exchanger , connecting the thermal storage system to the power cycle, needs to ben designed and here is where I intervene.
Before I came, it was already decided, that the power cycle uses supercritical fluid as working fluid and working fluid in the thermal energy storage circuit, more specifically the hot fluid, is CO2 at atmospheric pressure. It was also decided that the heat exchanger type is a printed circuit heat exchanger (PCHE), that the heat transfer rate is set to 10 MW and the hot fluid inlet temperature is 600 °C. However, to completely determine the geometry of the PCHE, the boundary conditions, i.e. temperature, pressure and mass flow rates in hot and cold channels, need to be determined.
To that end, a review of cycles and their modelling is made. It helps to calculate the boundary conditions for the cold side. Then, a cost-optimization analysis of the PCHE leads to determine the boundary conditions of the hot fluid. Indeed, as the hot fluid is CO2 at atmospheric pressure, even the smaller pressure drop has a significant impact on the operation cost of the PCHE. Therefore, a reference case may be determined.
Finally, CFD simulations were conducted on the reference case geometry. Furthermore, the behaviour of the PCHE is examined, when the mass flow rate is changed, e.g. because of different system operation. Finally, the CFD simulation results are compared to existing correlations.

Online-adaptive particle therapy: Current status and vision for the future
Richter, Christian

The lecture will give an overview of the utilization of prompt-gamma (PG) radiation, emitted from the
patient’s body during fractionated particle therapy treatment, for range and treatment verification.
After the nuclear physics basics of the emission of prompt gamma rays have been refreshed, the three
fundamental approaches for PG-based particle range determination will be discussed, which use
either spatial, temporal or spectroscopic information of PG - namely prompt gamma imaging (PGI),
prompt gamma timing (PGT) and prompt gamma spectroscopy (PGS), respectively. Special emphasis
will be on the interpretation of the complex PG data for the distinction of clinically relevant from
irrelevant treatment deviations, necessary for the clinical application of PG for treatment intervention in an online-adaptive PT realization. Results from the evaluation of clinically acquired PGI data will be
presented

Next-generation radiation therapy: Towards near-realtime adaptive proton therapy

Highlights in der Medizinphysik

In radiation oncology, CT imaging is of crucial importance for consistent and accurate delineation of target and organ-at-risk structures as well as for highly precise treatment planning and prediction of the deposited dose. Even though the potential benefit of dual-energy CT for those purposes was identified early, its implementation in clinical practice is still in an early stage. Here, we want to give an overview of current and potential future applications of dual-energy CT in the field of radiation oncology. Since the next generation of X-ray computed tomography with a photon-counting detector technology is rising at the horizon, we also want to give an outlook on radiotherapeutic applications that will benefit or even become possible for the first time with this technological evolution.

A combination of biochemical preparation methods with microscopic, spectroscopic, and mass spectrometric analysis techniques as contemplating state of the art application, was used for direct visualization, localization, and chemical identification of europium in plants. This works illustrates the chemical journey of europium (Eu(III)) through winter rye (Secale cereale L.), providing insight into the possibilities of speciation for Rare Earth Elements (REE) and trivalent f-elements. Kinetic experiments of contaminated plants show a maximum europium concentration in Secale cereale L. after four days. Transport of the element through the vascular bundle was confirmed with Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDS). For chemical speciation, plants were grown in a liquid nutrition medium, whereby Eu(III) species distribution could be measured by mass spectrometry and luminescence measurements. Both techniques confirm the occurrence of Eu malate species in the nutrition medium, and further analysis of the plant was performed. Luminescence results indicate a change in Eu(III) species distribution from root tip to plant leaves. Microscopic analysis show at least three different Eu(III) species with potential binding to organic and inorganic phosphate groups and a Eu(III) protein complex. With plant root extraction, further europium species could be identified by using Electrospray Ionization Mass Spectrometry (ESI MS). Complexation with malate, citrate, a combined malate-citrate ligand, and aspartate was confirmed mostly in a 1:1 stoichiometry (Eu:ligand). The combination of the used analytical techniques opens new possibilities in direct species analysis, especially regarding to the understanding of rare earth elements (REE) uptake in plants. This work provides a contribution in better understanding of plant mechanisms of the f-elements and their species uptake.

A look through almost 2000 abstracts submitted for the upcom-
ing ESTRO 2022 meeting together with a glance back on the 2021
papers published in Radiotherapy and Oncology gives one a good
impression of the (current) key focus areas in radiation oncology:
Almost all of this work relates to optimal delivery of radiation ther-
apy in terms of technology, quality assurance and morbidity reduc-
ing approaches. Thus, at present the research questions considered
as most relevant for radiotherapy of e.g. lung and oesophageal can-
cer are not related to tumour control, but to the late risk of cardiac
disease in the patients who are lucky to survive their cancer long
enough to develop such problems [1]. The same scenario is found
in the patient cohort that constitutes the largest indication for
radiotherapy in Europe: women with early breast cancer [2]. In
these examples, and in many other situations where radiotherapy
is applied with a curative intent, less focus has currently been
given to the aim or indication of the treatment, namely the control
of loco-regional malignant disease. Of course, since Holthusen’s
seminal paper in 1936 [3] the overall aim of radiotherapy, as stated
over and over again by all teachers in the field (including the
authors of this editorial), is uncomplicated tumour control, i.e.
loco-regional tumour control without severe normal tissue damage
(therapeutic ratio). This implies that rigorous study of the effects of
radiotherapy on normal, non-tumour, tissues is an absolute necessity. Yet, the prescription of radiotherapy in clinical practice is
done to kill tumour cells for local and loco-regional control. If the
effects of radiotherapy on tumours are shifting out of focus, it
might be taken for granted that the indication, dose, fractionation,
and potential multidisciplinary interactions in this field are fully
understood, and what remains is the fine tuning of the associated
risk of morbidity.

Solid lubricants, like ta-C (hydrogen-free tetrahedral amorphous carbon) coatings, are an active area of research to replace liquid lubricants. This substitution is important because of the negative environmental impact and high material consumption of liquid lubricants. The influence of soft metal counter bodies on the unlubricated friction behaviour of hydrogen-free carbon coatings has mostly been studied for doped a-C coatings so far. All these studies show that low friction and wear can only be achieved if a tribolayer is formed to protect the contact. Even with a formed tribolayer, its composition is crucial for the frictional behaviour, making the investigation of this composition essential. A study currently underway aims to identify friction-induced surface changes like material loss of the coating, material transfer between the counter body and the coating, or the formation of a tribolayer.
The current work presents Ion Beam Analysis methods to deliver laterally and depth-resolved element analysis of the wear track on the coating and the contact area of the counter bodies (CB). In a first test, a ta-C coating has been subjected to pin-on-disk tests with various metallic and ceramic CBs. He and H ion microbeams have been used to scan over the tracks and the contact areas of the CBs. Both RBS and PIXE have been used and first results are presented. It is shown that, in this case, RBS yields the more useful information. Both, a 2 MeV He ion beam and a 3 MeV H ion beam provide valuable results. The advantages of each type of ion beam depend on the sample and the information needed. As shown in this work, RBS with a 2 MeV He ion beam is useful to determine the transfer layer of a (soft) metal CB to the ta-C coating, whereas 3 MeV H RBS can be used to determine the presence of C and O on the CB because of the increased non-Rutherford cross-sections for these elements.

Purpose/objective: Experimental in vivo determination of radiological tissue parameters of organs in the
head and pelvis within a large patient cohort, expanding on the current standard human tissue database
summarized in ICRU46.
Material/methods: Relative electron density (RED), effective atomic number (EAN) and stopping-power
ratio (SPR) were obtained from clinical dual-energy CT scans using a clinically validated DirectSPR imple-
mentation and organ segmentations of 107 brain-tumor (brain, brainstem, spinal cord, chiasm, optical
nerve, lens) and 120 pelvic cancer patients (prostate, kidney, liver, bladder). The impact of contamination
by surrounding tissues on the tissue parameters was reduced with a dedicated contour adaption routine.
Tissue parameters were characterized regarding the cohort mean value as well as the variation within
each patient (2rintra) and between patients (2rinter ). For the brain, age-dependent differences were deter-
mined.
Results: For 10 organs, including 4 structures not listed in ICRU46, the mean RED, EAN and SPR as well as
their respective intra- and inter-patient variation were determined. SPR intra-patient variation was
higher than 1.3% (1.3–4.6%) in all organs and always exceeded the inter-patient variation of the organ
mean SPR (0.6–2.1%). For the brain, a significant SPR variation between pediatric and non-pediatric
patients was determined.
Conclusion: Radiological tissue parameters in the head and pelvis were characterized in vivo for a large
patient cohort using dual-energy CT. This reassesses parts of the current standard database defined in
ICRU46, furthermore complementing the data described in literature by smaller substructures in the
brain as well as by the quantification of organ-specific inter- and intra-patient variation.

Bronchialkarzinome sind in Deutschland
die dritthäufigste Tumorerkrankung. Trotz
erheblicher therapeutischer Fortschritte ist
die Prognose der Lungentumoren nach
wie vor ungünstig, die relative 5-Jahres-
Überlebensrate nach Diagnose eines Bron-
chialkarzinoms beträgt lediglich 16 % [3].
Hinsichtlich der Tumorart werden nicht-
kleinzellige (NSCLC) und kleinzellige Bron-
chialkarzinome unterschieden.
Bei fortgeschrittenen NSCLC besteht
die Standardtherapie aus einer gleichzei-
tig durchgeführten Radiochemotherapie,
gefolgt von einer Immuntherapie. In
Metaanalysen konnte die Überlegenheit
der simultanen Radiochemotherapie ge-
genüber einem sequenziellen Vorgehen
gezeigt werden.

Hydrogen evolution in acidic aqueous electrolytes was recently found to be characterized by a
carpet of microbubbles covering the microelectrode and feeding the growth of the main bubbles by
coalescence. Besides this, oscillatory behavior of the main bubbles was observed prior to departure.
Extending earlier studies, this work delivers the forces acting on the main bubble more accurately
by taking into account further geometric and electrochemical details measured during experiments.
Combining simulation work and measurements makes it possible to confirm the role of an attractive
electrical (Coulomb) force caused by the adsorption of hydrogen ions at the bubble interface and to
obtain a better understanding of the bubble dynamics observed.

Der Terahertz-Frequenzbereich umfasst ein technisch wenig erschlossenes Grenzgebiet im elektromagnetischen Spektrum. Er ist aber besonders interessant, weil er viele Eigenfrequenzen verschiedener, komplexer Quantenphänomene enthält. Dafür stehen neuerdings intensive Terahertz-Pulse aus spezialisierten Elektronenbeschleunigerquellen zur Verfügung. Sie bieten nun eine einzigartige Möglichkeit, solch fundamentale Quantenprozesse im Nichtgleichgewicht zu untersuchen

We are witnessing a great transition towards a society powered by renewable energies to meet the ever-stringent climate target. Hydrogen, as an energy carrier, will play a key role in building a climate-neutral society. Although liquid hydrogen is essential for hydrogen storage and transportation, liquefying hydrogen is costly with the conventional methods based on Joule-Thomas effect. As an emerging technology which is potentially more efficient, magnetocaloric hydrogen liquefaction can be a “game-changer”. In this work, we have investigated the rare-earth-based Laves phases RAl and RNi₂ for magnetocaloric hydrogen liquefaction. We have noticed an unaddressed feature that the magnetocaloric effect of second-order magnetocaloric materials can become “giant” near the hydrogen boiling point. This feature indicates strong correlations, down to the boiling point of hydrogen, among the three important quantities of the magnetocaloric effect: the maximum magnetic entropy change ΔS^max _m, the maximum adiabatic temperature change ΔT^max _ad , and the Curie temperature T_C. Via a comprehensive literature review, we interpret the correlations for a rare-earth intermetallic series as two trends: (1) ΔS^max _m increases with decreasing T_C; (2) ΔT^max _ad decreases near room temperature with decreasing T_C but increases at cryogenic temperatures. Moreover, we have developed a mean-field approach to describe these two trends theoretically. The dependence of ΔS^max _m and ΔT^max _ad on T_C revealed in this work helps researchers quickly anticipate the magnetocaloric performance of rare-earth-based compounds, guiding material design and accelerating the discoveries of magnetocaloric materials for hydrogen liquefaction.

The applicability of radioligands for targeted endoradionuclide therapy is limited due to radiation-induced deleterious effects to healthy tissues. This applies in particular to the kidneys as primary organs of elimination, which requires dosimetric estimates to justify internal radionuclide therapy. In this context, the targeting of enzymes of the renal brush border membrane by cleavable linkers between target molecule and radiolabel that permit the formation of fast eliminating radionuclide-carrying cleavage fragments gains increasing interest. Herein, we synthesized a small library of ⁶⁴Cu-labeled cleavable linkers and quantified their substrate potentials toward neprilysin (NEP), a highly abundant peptidase at the renal brush border membrane. This allowed for the derivation of structure-activity relationships and selected cleavable linkers were attached to the somatostatin receptor subtype 2 ligand [Tyr³]octreotate. Subsequent radiopharmacological characterization revealed that a substrate-based targeting of NEP in the kidneys with small molecules or peptides entails a certain degree of premature cleavage in the blood circulation by soluble and endothelium-derived NEP. However, for a tissue-specific targeting of NEP in the kidneys, the additional targeting of albumin in the blood by albumin-binding moieties is highlighted.

To optimize neoadjuvant radiochemotherapy of pancreatic ductal adenocarcinoma (PDAC),
the value of new irradiation modalities such as proton therapy needs to be investigated in relevant
preclinical models. We studied individual treatment responses to RCT using patient-derived PDAC
organoids (PDO). Four PDO lines were treated with gemcitabine, 5-fluorouracile (5FU), photon and
proton irradiation and combined RCT. Therapy response was subsequently measured via viability
assays. In addition, treatment-naive PDOs were characterized via whole exome sequencing and
tumorigenicity was investigated in NMRI Foxn1nu/nu mice. We found a mutational pattern con-
taining common mutations associated with PDAC within the PDOs. Although we could unravel
potential complications of the viability assay for PDOs in radiobiology, distinct synergistic effects
of gemcitabine and 5FU with proton irradiation were observed in two PDO lines that may lead to further mechanistical studies. We could demonstrate that PDOs are a powerful tool for translational
proton radiation research.

High-quality randomised clinical trials testing moderately fractionated breast radiotherapy have clearly shown that
local control and survival is at least as effective as with 2 Gy daily fractions with similar or reduced normal tissue
toxicity. Fewer treatment visits are welcomed by patients and their families, and reduced fractions produce substantial
savings for health-care systems. Implementation of hypofractionation, however, has moved at a slow pace. The
oncology community have now reached an inflection point created by new evidence from the FAST-Forward five-
fraction randomised trial and catalysed by the need for the global radiation oncology community to unite during the
COVID-19 pandemic and rapidly rethink hypofractionation implementation. The aim of this paper is to support
equity of access for all patients to receive evidence-based breast external beam radiotherapy and to facilitate the
translation of new evidence into routine daily practice. The results from this European Society for Radiotherapy and
Oncology Advisory Committee in Radiation Oncology Practice consensus state that moderately hypofractionated
radiotherapy can be offered to any patient for whole breast, chest wall (with or without reconstruction), and nodal
volumes. Ultrafractionation (five fractions) can also be offered for non-nodal breast or chest wall (without
reconstruction) radiotherapy either as standard of care or within a randomised trial or prospective cohort. The
consensus is timely; not only is it a pragmatic framework for radiation oncologists, but it provides a measured
proposal for the path forward to influence policy makers and empower patients to ensure equity of access to evidence-
based radiotherapy.

Purpose: To develop prognostic biomarker signatures for patients with locally advanced head and neck
squamous cell carcinoma (HNSCC) treated by primary radiochemotherapy (RCTx) based on previously
published molecular analyses of the retrospective biomarker study of the German Cancer Consortium
– Radiation Oncology Group (DKTK-ROG).

4D multi-image-based (4DMIB) optimization is a form of robust optimization where different uncertainty
scenarios, due to anatomy variations, are considered via multiple image sets (e.g., 4DCT). In this review,
we focused on providing an overview of different 4DMIB optimization implementations, introduced var-
ious frameworks to evaluate the robustness of scanned particle therapy affected by breathing motion and
summarized the existing evidence on the necessity of using 4DMIB optimization clinically. Expected
potential benefits of 4DMIB optimization include more robust and/or interplay-effect-resistant doses for
the target volume and organs-at-risk for indications affected by anatomical variations (e.g., breathing,
peristalsis, etc.). Although considerable literature is available on the research and technical aspects of
4DMIB, clinical studies are rare and often contain methodological limitations, such as, limited patient
number, motion amplitude, motion and delivery time structure considerations, number of repeat CTs,
etc. Therefore, the data are not conclusive. In addition, multiple studies have found that robust 3D opti-
mized plans result in dose distributions within the set clinical tolerances and, therefore, are suitable for a
treatment of moving targets with scanned particle therapy. We, therefore, consider the clinical necessity
of 4DMIB optimization, when treating moving targets with scanned particle therapy, as still to be
demonstrated.

Human papillomavirus (HPV)-driven head and neck squamous cell carcinomas (HNSCC)
generally have a more favourable prognosis. We hypothesized that HPV-associated HNSCC may
be identified by an miRNA-signature according to their specific molecular pathogenesis, and be
characterized by a unique transcriptome compared to HPV-negative HNSCC. We performed miRNA
expression profiling of two p16/HPV DNA characterized HNSCC cohorts of patients treated by
adjuvant radio(chemo)therapy (multicentre DKTK-ROG n = 128, single-centre LMU-KKG n = 101).
A linear model predicting HPV status built in DKTK-ROG using lasso-regression was tested in
LMU-KKG. LMU-KKG tumours (n = 30) were transcriptome profiled for differential gene expression
and miRNA-integration. A 24-miRNA signature predicted HPV-status with 94.53% accuracy (AUC:
0.99) in DKTK-ROG, and 86.14% (AUC: 0.86) in LMU-KKG. The prognostic values of 24-miRNA-
and p16/HPV DNA status were comparable. Combining p16/HPV DNA and 24-miRNA status
allowed patient sub-stratification and identification of an HPV-associated patient subgroup with
impaired overall survival. HPV-positive tumours showed downregulated MAPK, Estrogen, EGFR,
TGFbeta, WNT signaling activity. miRNA-mRNA integration revealed HPV-specific signaling pathway
regulation, including PD−L1 expression/PD−1 checkpoint pathway in cancer in HPV-associated HNSCC.
Integration of clinically established p16/HPV DNA with 24-miRNA signature status improved
clinically relevant risk stratification, which might be considered for future clinical decision-making
with respect to treatment de-escalation in HPV-associated HNSCC.

While according to the state of the art safety analyses related to nuclear reactor thermal hydraulics are done using system codes, CFD becomes more and more important as a tool to support such analyses. Often multiphase flows are involved in the flow situations that have to be considered. For medium and large scales, as they are typical in nuclear reactor safety research, the Euler-Euler (E-E) approach is most suited and most frequently used. However, E-E-CFD is not yet mature. A consolidation of closure models is required to enable reliable predictions. The baseline model concept is a promising way to reach such a consolidation. A baseline model for poly-disperse bubbly flows is established and implemented in the OpenSource CFD package OpenFOAM (Foundation release). The sustainable development requires quality insurance and continuous maintenance of the corresponding OpenFOAM-add-ons which is enabled in the GitLab environement. An automated workflow helps efficiently to support the step-by-step improvement of the baseline model. The lecture presents the baseline model conceptand the general strategy for its further development. This is illustrated by the example of the baseline model for poly-disperse flows. Advantages as well as challenges related to the use of Open Source software in NRS are discussed.

The new Medical Licensing Regulations 2025 (Ärztliche Approbationsordnung, ÄApprO) will soon be passed by the Federal Council (Bundesrat) and will be implemented step by step by the individual faculties in the coming months. The further development of medical studies essentially involves an orientation from fact-based to competence-based learning and focuses on practical, longitudinal and interdisciplinary training. Radiation oncology and radiation therapy are important components of therapeutic oncology and are of great importance for public health, both clinically and epidemiologically, and therefore should be given appropriate attention in medical education. This report is based on a recent survey on the current state of radiation therapy teaching at university hospitals in Germany as well as the contents of the National Competence Based Learning Objectives Catalogue for Medicine 2.0 (Nationaler Kompetenzbasierter Lernzielkatalog Medizin 2.0, NKLM) and the closely related Subject Catalogue (Gegenstandskatalog, GK) of the Institute for Medical and Pharmaceutical Examination Questions (Institut für Medizinische und Pharmazeutische Prüfungsfragen, IMPP). The current recommendations of the German Society for Radiation Oncology (Deutsche Gesellschaft für Radioonkologie, DEGRO) regarding topics, scope and rationale for the establishment of radiation oncology teaching at the respective faculties are
also included.

Glioblastoma is a devastating malignant disease with poor patient overall survival. Strong invasiveness and resistance to radiochemotherapy have challenged the identification of molecular targets that can finally improve treatment outcomes. This study evaluates the influence of all six known p21-activated kinase (PAK) protein family members on the invasion capacity and radioresponse of glioblastoma cells by employing a siRNA-based screen. In a panel of human glioblastoma cell models, we identified PAK4 as the main PAK isoform regulating invasion and clonogenic survival upon irradiation and demonstrated the radiosensitizing potential of PAK4 inhibition. Mechanistically, we show that PAK4 depletion and pharmacological inhibition enhanced the number of irradiation- induced DNA double-strand breaks and reduced the expression levels of various DNA repair proteins.
In conclusion, our data suggest PAK4 as a putative target for radiosensitization and impairing DNA repair in glioblastoma, deserving further scrutiny in extended combinatorial treatment testing.

Targeted Alpha Therapy is a research field of highest interest in specialized radionuclide therapy. Over the last decades, several alpha-emitting radionuclides have entered and left research topics towards their clinical translation. Especially, 225Ac provides all necessary physical and chemical properties for a successful clinical application, which has already been shown by [225Ac]Ac PSMA 617. While PSMA 617 carries the DOTA as the complexing agent, the chelator macropa as macrocyclic alternative provides even more beneficial properties regarding labeling and complex stability in vivo. Lanthanum-133 is an excellent positron-emitting diagnostic lanthanide to radiolabel macropa-functionalized therapeutics, since 133La forms a perfect matched theranostic pair of radionuclides with the therapeutic radionuclide actinium-225 which itself can optimally be complexed by macropa as well. 133La was thus produced by cyclotron-based proton irradiation of an enriched 134Ba target. The target (30 mg of [134Ba]BaCO3) was irradiated for 60 min at 22 MeV and 10-15 µA beam current. Irradiation side products in the raw target solution were identified and quantified: 135La (0.4%), 135mBa (0.03%), 133mBa (0.01%) and 133Ba (0.0004%). The subsequent work-up and anion-exchange-based product purification process took approx. 30 min and led to a total amount of (1.2 – 1.8) GBq (decay-corrected to EOB) of 133La, formulated as [133La]LaCl3. After complete decay of 133La, a remainder of ca. 4 kBq of long-lived 133Ba per 100 MBq of 133La was detected and rated as uncritical regarding personal dose and waste management. Subsequent radiolabeling was successfully performed with previously published macropa-derived PSMA inhibitors at a micromolar range (quantitative labeling at 1 µM) and evaluated by radio-TLC and radio-HPLC analyses. The scale up to radioactivity amounts that are needed for clinical application purposes would be easy to achieve by increasing target mass, beam current and/or irradiation time to produce 133La of high radionuclide purity (>99.5%) regarding labeling properties and side products.

Die Fallstudie behandelt einen großtechnischen Recyclingversuch von 100 Kühlgeräten aus dem Haushaltsbereich in einer gewerblichen Erstbehandlungsanlage. Neben der Beobachtung von Be-handlungsschritten wie z. B. der Kompressordemontage wurden die Produktfraktionen Eisen, Nichteisen und Kunststoffe für drei Kühlgerätegruppen näher analysiert. Dabei wurde ein besonde-rer Fokus auf die Analyse von Restverbunden gelegt. Die Versuchsergebnisse ermöglichen eine Unterscheidung zwischen Restverbunden, welche im Prozess gebildet wurden, und anderen, die durch den konstruktiven Aufbau bedingt sind. Dadurch können Potenziale für ein recyclinggerech-teres Design von Kühlgeräten und Herausforderungen bei der Aufschlusszerkleinerung gezeigt werden. Außerdem können beispielsweise Leiterplatten für die Demontage leichter zugänglich an-geordnet werden und Kompressoren eine einfacher und schneller lösbare Befestigung haben. Zu-dem kann ein Auslassventil beim verlustfreien Trockenlegen des Kältekreislaufes helfen.

I will discuss some developments related to two types of THz sources: on the one hand photoconductive antennas, including recent results using the material germanium, and on the other hand I will give an overview on the accelerator based coherent infrared and THz sources operating at HZDR, and discuss plans for a successor facility.

First studies on range verification in proton therapy using prompt gamma-ray spectroscopy (PGS) or imaging (PGI) have been recently conducted with patients. To benchmark the performance of each method, we designed a multi-center experiment between Massachusetts General Hospital and OncoRay with a shared anthropomorphic head phantom irradiated under equalized conditions. The treatment plan was delivered at clinical beam currents and doses in the respective proton therapy hospitals. Two gantry beam angles were used: horizontal and oblique (270° and 350°). Each field contained the same spot positions and energies as well as target volume in both institutions. The experimentally measured range was compared against the ground truth based on the reference stopping-power
map of the phantom. The absolute range error of PGS or PGI was 2.4 mm or -0.5 mm for the horizontal field and 1.3 mm or 2.4 mm for the oblique one, respectively. The ability to detect relative range deviations was assessed by introducing 2 mm and 5 mm plastic slabs on the ventral half of the horizontal field. The measured range shifts were 1.8 mm or 4.8 mm for PGS, and 2.0 mm or 4.2 mm for PGI, respectively. The designed set of experiments represents the first systematic comparison of prompt gamma-ray systems for proton range verification across different institutions using a ground-truth head phantom as reference, and effectively proposes a standard testing platform for benchmarking future proton range verification prototypes in reproducible conditions.

The quality of the photocathodes is critical for the stable operation of the electron sources of the accelerator-based light sources (for example X-ray FEL at DESY [1], THz at ELBE [2], etc). In this field, high quantum efficiency (QE) and long operation lifetime are the most important parameters for the ideal photocathode materials. Cs2Te photocathodes have been successfully applied in the e- guns at DESY and in the superconducting RF gun at HZDR. Recently GaN as a new photocathode candidate has been paid more and more attention because of its high QE and robustness. However, even under the extremly high vacuum environment, photocathodes lose QE slowly and change the QE distribution during the operation. In this contribution, we will present the surface study on the Cs2Te and GaN photocathodes, including the QE evolution during operation (see Fig. 1) and the XPS analysis of the 'used' photocathodes (see Fig. 2). Several possible reasons leading degradation of those photocathodes might be: 1. rest gases during operation react with the sensitive alkali-rich surface; 2. the low energy ions, ionized rest gas molecules by the electrons, reach the cathode surface and react with the surface.

COX-2 can be considered as a clinically relevant molecular target for adjuvant, in particular radiosensitizing treatments. In this regard, using selective COX-2 inhibitors, e.g., in combination with radiotherapy or endoradiotherapy, represents an interesting treatment option. Based on our own findings that nitric oxide (NO)-releasing and celecoxib-derived COX-2 inhibitors (COXIBs) showed promising radiosensitizing effects in vitro, we herein present the development of a series of eight novel NO-COXIBs differing in the peripheral substitution pattern and their chemical and in vitro characterization. COX-1 and COX-2 inhibition potency was found to be comparable to the lead NO-COXIBs, and NO-releasing properties were demonstrated to be mainly influenced by the substituent in 4-position of the pyrazole (Cl vs. H). Introduction of the N-propionamide at the sulfamoyl residue as a potential prodrug strategy lowered lipophilicity markedly and abolished COX inhibition while NO-releasing properties were not markedly influenced. NO-COXIBs were tested in vitro for a combination with single-dose external X-ray irradiation as well as [ 177Lu]LuCl3 treatment in HIF2α-positive mouse pheochromocytoma (MPC-HIF2a) tumor spheroids. When applied directly before X-ray irradiation or 177Lu treatment, NO-COXIBs showed radioprotective effects, as did celecoxib, which was used as a control. Radiosensitizing effects were observed when applied shortly after X-ray irradiation. Overall, the NO-COXIBs were found to be more radioprotective compared with celecoxib, which does not warrant further preclinical studies with the NO-COXIBs for the treatment of pheochromocytoma. However, evaluation as radioprotective agents for healthy tissues could be considered for the NO-COXIBs developed here, especially when used directly before irradiation.

The cost-effective production of large amounts of green hydrogen using a new generation of proton exchange membrane (PEM) electrolyzers generates very high gas fractions in the anode circuit, resulting from the high current densities. The volume fraction of oxygen prevails over the volume fraction of hydrogen by a factor of 20. The main goal for the separation process of oxygen from the two-phase flow mixture is a completely gas-free operation fluid before the water enters the heat exchanger. Furthermore, the local instantaneous oxygen fraction represented by partially fine dispersed bubbles related to the full oxygen amount in the anode circuit is still unknown and should be investigated. Due to the development of new separation concepts with high separation efficiency, the measurement of gas holdup and bubble size are carried out using a capacitance wire-mesh sensor (WMS), optical channel body flow sensor, and optical microscope. This poster was prepared for the H2Giga status conference and provides an overview of measurement techniques used in the project.

Project
The authors acknowledge the financial support by the Federal Ministry of Education and Research of Germany in the programme ”H2GIGA”. Project identification number: 03HY123E.

B20-type MnSi is the prototype magnetic skyrmion material. Thin films of MnSi show a higher Curie temperature than their bulk counterpart. However, it is not yet clear what mechanism leads to the increase of the Curie temperature. In this work, we grow MnSi films on Si(100) and Si(111) substrates with a broad variation in their structures. By controlling the Mn thickness and annealing parameters, the pure MnSi phase of polycrystalline and textured nature as well as the mixed phase of MnSi and MnSi1.7 are obtained. Surprisingly, all these MnSi films show an increased Curie temperature of up to around 43 K. The Curie temperature is likely independent of the structural parameters within our accessibility including the film thickness above a threshold, strain, cell volume and the mixture with MnSi1.7. However, a pronounced phonon softening is observed for all samples, which can tentatively be attributed to slight Mn excess from stoichiometry, leading to the increased Curie temperature.

For a safe enclosure of contaminants, for instance in deep geological repositories of radioactive waste, any processes retarding metal migration are of paramount importance. This study focusses on the sorption of trivalent actinides (Am, Cm) and lanthanides (Eu) to the surface of muscovite, a mica and main component of most crystalline rocks (granites, granodiorites). Batch sorption experiments quantified the retention regarding parameters like pH (varied between 3 and 9), metal concentration (from 0.5 µM Cm to 10 µM Eu), or solid-to-liquid ratio (0.13 and 5.25 g·L-1). In addition, time-resolved laser fluorescence spectroscopy (TRLFS) using the actinide Cm(III) identified two distinct inner-sphere surface species. Combining both approaches allowed the development of a robust surface complexation model and the determination of stability constants of the spectroscopically identified species of (≡S OH)2M3+ (logKo −8.89), (≡S O)2M+ (logKo −4.11), and (≡S-O)2MOH (logKo −10.6), with all values extrapolated to infinite dilution. The inclusion of these stability constants into thermodynamic databases will improve the prognostic accuracy of lanthanide and actinide transport through groundwater channels in soils and crystalline rock systems.

The purpose of this task is to coordinate with the e-platforms providers (ESRF for PaNOSC and EGI for EOSC-hub) to jointly define the prerequisites to maximise and expand the use of the platforms as appropriate. WP2, WP3 and WP4 will work closely with WP5 and WP6 to deliver a tailored specification for each of the online training modules. The output of WP5 will be a definition of the most suitable training materials in accordance with the requirements and recommendations made by the targeted e-platform providers.
A unique joint PaN training portal has been developed and deployed to provide both a training material and events catalogue (ExPaNDS) as well as an e-learning system (PaNOSC) under the domain pan-training.eu.

For a comprehensive safety assessment of a nuclear repository, the influence of naturally occurring microorganisms from deep geological layers has to be taken into account. Clay rock represents a suitable host rock for the long-term storage of high-level radioactive waste with bentonite as backfill material. In the event of a worst-case scenario, water can enter the repository, solubilize components of the waste, and transport it into the surrounding barriers. In this case, microorganisms can interact with the radionuclides and thereby change the chemical speciation or induce redox reactions.
Desulfosporosinus species represent important members of anaerobic, sulfate-reducing bacteria present in both, clay rock and bentonite. They occur, among others, in the pore water of Opalinus Clay and in the Bavarian bentonite B25. [1,2] Desulfosporosinus hippei DSM 8344T is a close phylogenetic relative to an isolated bacterium from bentonite samples. [3] Therefore, this strain was selected to get a more profound insight into the uranium(VI) interactions, especially regarding the reduction to the less mobile uranium(IV).
Artificial Opalinus Clay pore water [4] served as background electrolyte for the reduction experiments (100 µM uranium(VI), pH 5.5), in which the uranium concentrations in the supernatants decreased rapidly. Time-resolved laser-induced fluorescence spectroscopy showed the presence of a uranyl lactate and a uranyl carbonate complex as aqueous species in the supernatant. While the proportion of the uranyl lactate complex decreased with the incubation time, the uranyl carbonate fraction remained almost constant.
UV/Vis studies of the dissolved cell pellets provided clear proof of a partial reduction of uranium(VI) to uranium(IV) of up to 39% in the samples. Therefore, a combined association-reduction process is a possible interaction mechanism.
TEM images showed the presence of uranium-containing aggregates on the cell surface. To mitigate encrustation, cells released membrane vesicles as a possible defense mechanism.
In addition, uranium(VI) reduction was confirmed by HERFD-XANES measurements. Moreover, uranium(V) could be detected as an intermediate, providing first evidence of the involvement of uranium(V) in uranium(VI) reduction by sulfate-reducing microorganisms. EXAFS measurements helped to identify different cell-related uranium species.
This study helps to improve the understanding of the complexity of uranium-microbe interactions relevant to the long-term storage of high-level radioactive waste in clay rock and therefore contributes to a safety concept for a nuclear repository in this host rock.
References:
[1] Bagnoud et al. (2016) Nat. Commun 7, 1–10.
[2] Matschiavelli et al. (2019) Environ. Sci. Technol. 53, 10514–10524.
[3] Vatsurina et al. (2008) Int. J. Syst. Evol. Microbiol. 58, 1228–1232.
[4] Wersin et al. (2011) Appl. Geochemistry 26, 931–953.

Magnetic data can be acquired from a number of different platforms (e.g., ground, drone, helicopter) using a variety of sensors (e.g., caesium vapour-type optically pumped magnetometers, fluxgate, superconducting quantum interference devices) with different flight line configurations. To detect a magnetic anomaly associated with a mineral commodity that is not exposed but is thought to be associated with the anomalous magnetic mineral content, it is necessary to optimize the survey parameters through a complete data integration process. Prior petrophysical measurements provide insight into the physical contrast that might be expected between adjacent lithologic units and between the ore zone and the encompassing lithology. Oriented rock samples provide access to magnetic remanence data through palaeomagnetic laboratory measurements. Knowing the typical morphology of the ore zone one can compute a forward model of the expected anomalous response and determine which combination of survey parameters provides the highest probability of detecting the commodity being sought. In this study, we analyse magnetic patterns associated with thin dipping skarn bodies from the Geyer mining district in Erzgebirge, Germany. Petrophysical measurements indicate that the skarns are more magnetic than the surrounding host rock. Partially oriented samples from a bore core record a Variscan age metamorphic remanence. Forward modelling indicates that clusters of skarn bodies are required to produce a reliably detectable magnetic signal. Ground, or low elevation drone surveys are needed to detect these anomalies with standard scalar-type optically pumped magnetometer or fluxgate magnetic surveys. The enhanced spatial resolution and long-wavelength rejection of a superconducting quantum interference device-based full-tensor magnetic gradiometer provide an improvement over optically pumped magnetometers for an aircraft-based survey platform.

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

The influence of different average and bunch dose rates in electron beams on the FLASH effect was investigated. The present study measures O2 content in water at different beam pulse patterns and finds strong correlation with biological data, strengthening the hypothesis of radical-related mechanisms as a reason for the FLASH effect.

We report results on the long-term variation of the neutron counting rate at the Canfranc Underground Laboratory, of importance for several low-background experiments installed there, including rare-event searches. The measurement campaign was performed employing the High Efficiency Neutron Spectrometry Array (HENSA) mounted in Hall A and lasted 412 live days. The present study is the first long-term measurement of the neutron rate with sensitivity over a wide range of neutron energies (from thermal up to 0.1 GeV and beyond) performed in any underground laboratory so far. Data on the environmental variables inside the experimental hall (radon concentration, air temperature, air pressure and humidity) were also acquired during all the measurement campaign. We have investigated for the first time the evolution of the neutron rate for different energies of the neutrons and its correlation with the ambient variables.

Summary of the CRC1415 project C03 progress. Published results since the beginning of the project were shown.

Modelling of 2D TMDC/2D perovskite heterostructures is shown together with experimental data. Nonradiative energy transfer and charge transfer were found to co-exist in this type of heterostructures.

Modelling of 2D van der Waals heterostructures is discussed from the point of view of complexity and desired property investigations. Different models are shown together with appropriate approached to simulate properties of materials.

Recent experiments by Geim’s group have demonstrated transport and separation of hydrogen isotopes through the van der Waals gap in hexagonal boron nitride (h-BN) and molybdenum disulfide (MoS2) bulk layered materials. The experiments could not distinguish whether the transported particles are protons (H+) or protium (H) atoms. In one of our recent works, we reported theoretical studies, which indicate that protium atoms, rather than protons, are transported through the gap.[1] First-principles calculations combined with well-tempered metadynamics simulations at finite temperature reveal that for h-BN and MoS2, the diffusion mechanism of both protons and protium (H) atoms involves a hopping process between adjacent layers. This process is assisted by low-energy phonon shear modes. The extracted diffusion coefficient of protium matches the experiment, while for protons, it is several orders of magnitude smaller. This indicates that H atoms are responsible for the experimental observations. These results allow for a comprehensive interpretation of experimental results on the transport of H isotopes through van der Waals gaps and can help identify other materials for hydrogen isotope separation applications.
In more recent investigations, we focus on H atom diffusion between layers of transition-metal dichalcogenides (TMDCs), such as MoS2, where we investigate the impact of transition metal atom, chalcogen atom, stacking order, and moiré pattern on the diffusion coefficients. We want to learn whether the free energy barriers are lowered (resulting in higher diffusion coefficients) and whether the moiré patterns can enforce directional transport.
We use well-tempered metadynamics simulations in our studies as implemented in the cp2k code. Our approach to H atom diffusion can be extended to investigations of other species, such as Eu(III)-species diffusion in clay mineral layered materials.
[1] Y. An, A. Kuc, P. Petkov, M. Lozada-Hidalgo, T. Heine, Small 1901722 (2019) 1-7.

In this summer school, I was introducing simulations of electronic and vibrational properties of 2D materials in the form of a lecture.

One of the most important techniques to separate valuable minerals from unwanted gangue is froth flotation. It is an efficient process for particles with sizes ranging from 10 µm to 200 µm and its main separation feature is the difference in particle wettabilities. As particles are getting finer, existing flotation techniques need to be adapted and improved in order to have an efficient separation. For that reason, this project, which is part of the German research foundation priority programme DFG-SPP 2045 “MehrDimPart”, aims at developing a method for the separation of ultrafine particles based on multiple particle properties, such as size, morphology or surface energy.
A particle system consisting of ultrafine size fractions of glass particles as the valuable material and magnetite as the gangue material is used for this study. The wettability of the glass particles is modified via an esterification reaction using alcohols with differing chain length and the resulting wettability states are analysed using inverse gas chromatography as well as analytic particle solvent extraction. Information on the particle size and shape are obtained via a combination of laser diffraction and microscopic analysis. The technique of flow cytometry is introduced for multidimensional particle characterization, as it allows for simultaneous size and shape analysis. Additionally, information on the particle wettability can be obtained by fluorescent marking of particles with dyes. All flotation tests are carried out in batch mode using a novel flotation apparatus, specifically designed for the flotation of ultrafine particles by combining advantages from machine-type froth flotation and column flotation and the separation process is evaluated using multidimensional partition curves.
This investigation will help to further understand how certain particle properties influence flotation, as well as other separation processes. In this way, the separation of ultrafine particles will be more efficient, which will play an important role in the recycling of secondary materials.