Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

In our recent work [L. Körber, AIP Advances 11, 095006 (2021)], we presented an efficient numerical method to compute dispersions and mode profiles of spin waves in waveguides with translationally invariant equilibrium magnetization. A finite-element method (FEM) allowed to model two-dimensional waveguide cross sections of arbitrary shape but only finite size. Here, we extend our FEM propagating-wave dynamic-matrix approach from finite waveguides to the important cases of infinitely-extended mono- and multilayers of arbitrary spacing and thickness. To obtain the mode profiles and frequencies, the linearized equation of motion of magnetization is solved as an eigenvalue problem on a one-dimensional line-trace mesh, defined along the normal direction of the layers. Being an important contribution in multilayer systems, we introduce interlayer exchange into our FEM approach. With the calculation of dipolar fields being the main focus, we also extend the previously presented plane-wave Fredkin-Koehler method to calculate the dipolar potential of spin waves in infinite layers. The major benefit of this method is that it avoids the discretization of any non-magnetic material like non-magnetic spacers in multilayers. Therefore, the computational effort becomes independent on the spacer thicknesses. Furthermore, it keeps the resulting eigenvalue problem sparse, which therefore, inherits a comparably low arithmetic complexity. As a validation of our method (implemented into the open-source finite-element micromagnetic package \textsc{TetraX}), we present results for various systems and compare them with theoretical predictions and with established finite-difference methods. We believe this method offers an efficient and versatile tool to calculate spin-wave dispersions in layered magnetic systems.

Rapidly developing additive technologies for metallic parts production have led to the development of a wide range of methods supporting this field, including mechanical properties characterization. Components produced by AM processes are built spot to spot and layer by layer and that leads to varying local heat absorption and distribution, resulting in varying local properties depending on the shape complexity and build parameters. Different properties in different directions and at various component locations can be expected. Since AM parts are often sub-scale and/or with topological complexity, mechanical characterization with the use of standard specimens is not typically possible and small-sized specimen techniques have to be developed and applied. In the current paper, three AM produced parts made of Ti-6Al-4V by Electron Beam Powder Bed Fusion (EB-PBF) technology have been investigated. Three material conditions are reported here: as-deposited, stress relieved and HIP-ed. Local mechanical properties are assessed with the use of miniaturized compact tension (MCT) fracture toughness specimens and miniaturized tensile tests (MTT). The results are complemented by microstructural and fractographic analysis and are discussed in the light of literature values. © 2022 Elsevier Ltd

Focused ion beam (FIB) processing with low-energy ions has become a standard technique for the manipulation of nanostructures. Many underlying ion beam effects that deviate from conventional high-energy ion irradiation of bulk systems are considered today; however, ion channeling with its consequence of significant deeper penetration depth has been only theoretically investigated in this regime. We present here an experimental approach to determine the channeling of low-energy ions in crystalline nanoparticles by measuring the sputter yield derived from scanning electron microscopy (SEM) images taken after irradiation under various incident ion angles. Channeling maps of 30 and 20 keV Ga+ ions in Ag nanocubes have been identified and fit well with the theory. Indeed, channeling has a significant impact on the transport of energetic ions in crystals due to the large critical angle at low ion energies, thus being relevant for any FIB-application. Consequently, the obtained sputter yield clearly differs from amorphous materials; therefore, it is recommended not to rely only on, e.g., ion distribution depths predicted by standard Monte-Carlo (MC) algorithms for amorphous materials.

Purpose: The physical integration of MRI with proton therapy (PT) into an MR-integrated PT (MRiPT) system is expected to improve the targeting accuracy of PT. The purpose of this project was to develop a prototype system combining a low-field in-beam MRI scanner with a proton pencil beam scanning (PBS) beamline to enable a first MRiPT treatment. This contribution presents first results of the installation and commissioning of the MRiPT system where the positioning reproducibility, magnet shimming performance and image quality with a focus on geometric fidelity were analyzed.

Methods: The MRiPT setup consists of an open C-shaped 0.32 T MRI scanner (MRJ3300, ASG Superconductors SpA, Genoa, Italy) positioned in close proximity of the nozzle of a horizontal proton PBS beamline (Figure 1). The MRI scanner was encased in a custom-designed compact aluminum Faraday cabin. At the location of the beam exit window of the nozzle, a beam entrance opening was incorporated in the wall of the RF cabin, which was sealed by a thin (30 µm) aluminum foil to combine high RF attenuation and small lateral spreading of the traversing proton beam. The scanner and RF cabin were mounted on top of an air-cushion-based transport platform, allowing the assembly to be accurately positioned in the beam path exiting the nozzle. The maneuvering of the assembly into treatment position was thereby visually guided based on room lasers that intersect at the beam isocenter and project onto the outer wall of the cabin. The magnet was shimmed in treatment position close to ferromagnetic components of the nozzle where the B0 field homogeneity was measured using a magnetic field camera (MFC3045, Metrolab Technology SA, Geneva, Switzerland). During commissioning the MR image quality was assessed using the ACR Small MRI Phantom (American College of Radiology, Virginia, USA) with T1w spin echo (SE) imaging, and the CIRS MRI-LINAC Dynamic Phantom (Computerized Imaging Reference Systems Inc., Norfolk, USA) with a T1w 3D spoiled gradient echo (GFE) pulse sequence dedicated for patient positioning control in the MRiPT workflow. The phantom allows for distortion analysis with 4 grid layers consisting of 5 concentric circles.

Results: The positioning accuracy and precision of the mobile in-beam MRI system were below 1 mm. A peak-to-peak B0 field homogeneity of 43 ppm over a 25 cm diameter spherical volume (DSV) around the MR magnetic isocenter was achieved during shimming. The ACR QA protocol revealed a signal-to-noise ratio (SNR) of >80 and a geometric distortion of <1.5 mm over a 10 cm DSV around the magnetic isocenter. The CIRS distortion measurement using the 3D GFE sequence showed that geometric distortion increased up to <8 mm at 20 cm DSV and <11 mm at 24 cm DSV.

Conclusion: A 0.32 T in-beam MRI scanner was successfully installed and commissioned in front of a horizontal proton PBS beamline in preparation for the development of a first prototype MRiPT system. Large volume image distortion measurements showed the necessity for geometric distortion correction algorithms in order to facilitate an accurate image guidance in a future MRiPT treatment.

Purpose: Magnetic resonance imaging-integrated proton therapy (MRiPT) is considered a next step in advancing image guidance for proton therapy as it is expected to improve the targeting precision. However, the presence of the MR magnetic field poses a challenge to the dose delivery due to the Lorentz force affecting the proton beam path. This study aims to investigate the dosimetric impact of the static magnetic (B0) field of an in-beam MR scanner on the delivery of scanned proton pencil beams.
Methods: An MRiPT prototype comprising a horizontal pencil beam scanning beamline and an open 0.32 T in-beam MR scanner with a B0 field oriented perpendicular to the central beam axis was used to measure the 2D dosimetric impact of the B0 imaging and fringe field on proton beam transport. Beam transmission measurements in-air were conducted for three proton energies (100, 150, and 220 MeV) and two spot maps (15×15 cm² and 30×20 cm²). 2D relative dose spot profiles were measured with EBT3 films placed vertically in the imaging field (position Pisoc) without and with the B0 field. Pisoc was located centrally in the imaging volume at 58.2 cm and 122.4 cm downstream of the beam isocenter and exit window, respectively. A 2D Gaussian fit was applied to each dose spot to determine its central position (X, Y), minimum and maximum lateral standard deviation (σ_min and σ_max), orientation (θ), and eccentricity (ε).
Results: Three concurrent effects were observed: (a) lateral beam deflection of all spots, (b) asymmetric trapezoidal deformation of the radiation field (Figure 1), and (c) deformation and rotation of individual dose spots. The lateral deflection was energy-dependent and consistent for both field sizes within the uncertainty of the measurements (Table 1). The field deformation was more pronounced for the 30×20 cm² field than for the 15×15 cm² field, indicating a field size dependence. At Pisoc for the 15×15 cm² field size 100 MeV beams the σ_max decreased by up to 3.66%, while σ_min increased by a maximum of 2.15%. The dose spot eccentricity underwent minor changes with a maximum decrease and increase in ε of 0.08 and 0.02, respectively. The spot orientation changed by a maximum θ of 5.39°. Similar effects were observed at the higher proton energies but to a lesser extent.
Conclusions: For the first time, the 2D dosimetric impact of scanned proton pencil beams traversing the B0 imaging and fringe field of an in-beam MR prototype on the proton beam path, radiation field shape, and dose spot form has been measured in air. The results demonstrate the complex energy- and position-dependent transport behaviour of the pencil beams that requires the 3D B0 field to be taken into account by future MRiPT treatment planning systems. Further investigations are mandatory to assess the dosimetric effects of the B0 field on proton beams delivered with range shifters positioned inside the B0 field and on beams delivered in homogeneous and inhomogeneous target volume media.

Purpose: In magnetic resonance imaging-integrated proton therapy (MRiPT), the magnetic field-dependent change in the dosage of ionisation chambers is considered by the correction factor k_(B ⃑,M,Q), which can be determined experimentally or computed via Monte Carlo (MC) simulations. In this work, k_(B ⃑,M,Q) for a plane-parallel ionisation chamber was determined by measurements and MC simulations were used to reproduce these results with high accuracy.
Material/Methods: The dose-response of the advanced Markus chamber (TM34045, PTW, Freiburg, Germany) irradiated with homogeneous 10x10 cm² mono-energetic fields, using 103.3, 153.1, and 252.7 MeV proton beams was measured in a water phantom placed in the magnetic field (MF) of an electromagnet with MF strengths of 0.32 and 1 T. The detector was positioned at a 2 cm water-equivalent depth with chamber electrodes parallel to the MF lines and perpendicular to the proton beam incidence direction. The measurements were compared with TOPAS MC simulations utilizing COMSOL-calculated 0.32 and 1 T MF maps of the electromagnet. k_(B ⃑,M,Q) was calculated for the measurements for all energies and MF strengths based on the equation: k_(B ⃑,M,Q)= M_Q/(M_Q^B ⃑ ), where M_Q and M_Q^B ⃑ were the temperature and air pressure corrected detector readings without and with MF, respectively. MC-based correction factors were determined as k_(B ⃑,M,Q)= D_det/(D_det^B ⃑ ), where D_det and D_det^B ⃑ were the doses deposited in the air cavity of the ionisation chamber model without and with MF, respectively.

Results: The detector showed a reduced dose-response for all measured energies, and MF strengths resulting in experimentally determined k_(B ⃑,M,Q) values larger than 1 (Figure 1). k_(B ⃑,M,Q) increased with proton energy and MF strength, except for 0.32 T and 252.7 MeV. Overall, k_(B ⃑,M,Q) ranged between 1.006 ± 0.004 and 1.021 ± 0.010 for all energies and MF strengths examined and the strongest dependence on energy was found at 1 T. The MC simulated k_(B ⃑,M,Q) values for 0.32 and 1 T showed a good agreement with the experimentally determined correction factors and trends within their standard deviations. The maximum difference between experimentally determined and MC simulated k_(B ⃑,M,Q) values was 0.63%.
Conclusion: For the first time, measurements and simulations were compared for an advanced Markus chamber for the dosimetry of protons within MFs. For both MF strengths, there was a good agreement of k_(B ⃑,M,Q) between experimentally determined and MC calculated values in this study. By benchmarking the MC code for calculation of〖 k〗_(B ⃑,M,Q) it can be used to calculate 〖 k〗_(B ⃑,M,Q) for various ionisation chamber models, MF strengths and proton energies in order to generate data needed for a dosimetry protocol for MRiPT.

First-principle calculations are performed to investigate Y substitutional defects at ground state and at 1000 K, for Ba- and Zr-rich chemical environments. In dependence on the Fermi level, at ground state singly positively charged Y may be potentially stable on Ba site (YBa1+) and neutral as well as singly negatively charged Y on Zr site ( YZr0 and YZr1-). However, using recent results for the doubly positively charged oxygen vacancy (VO2+) and taking account charge compensation, Fermi level pinning occurs, so that under Ba-rich conditions YZr1- and VO2+ are really stable. A similar consideration yields YBa1+ and YZr1- as stable defects in the Zr-rich case. Concerning VO2+, which occurrence is a prerequisite to obtain a good proton conductor, by Y doping, at ground state only in the Ba-rich case a moderate concentration can be formed. At 1000 K the situation is improved importantly. The consideration of vibrational contributions to the free formation energy of Y on Zr site shows an increase of the stability of YZr0 and YZr1-. Under Ba-rich conditions Fermi level pinning results in a free formation energy for VO2+ of 0.481 eV which corresponds to a high VO2+ concentration and optimum conditions for proton conduction. In Zr-rich case the respective value is 0.863 eV which leads also to relatively high VO2+ occurrence but the situation is somewhat less favourable than for the Ba-rich environment.

Background: The Editorial Board of EJNMMI Radiopharmacy and Chemistry releases a biannual highlight commentary to update the readership on trends in the field of radiopharmaceutical development.
Main body: This commentary of highlights has resulted in 21 different topics selected by each coauthoring Editorial Board member addressing a variety of aspects ranging from novel radiochemistry to first in man application of novel radiopharmaceuticals.
Conclusion: Trends in radiochemistry and radiopharmacy are highlighted demonstrating the progress in the research field in various topics including new PET-labelling methods, FAPI-tracers and imaging, and radionuclide therapy being the scope of EJNMMI Radiopharmacy and Chemistry.

When materials are exposed to X-ray pulses with sufficiently high intensity, various nonlinear
effects can occur. The most fundamental one consists of stimulated electronic decays after
resonant absorption of X-rays. Such stimulated decays enhance the number of emitted
photons and the emission direction is confined to that of the stimulating incident photons
which clone themselves in the process. Here we report the observation of stimulated reso-
nant elastic (REXS) and inelastic (RIXS) X-ray scattering near the cobalt L3 edge in solid Co/
Pd multilayer samples. We observe an enhancement of order 106 of the stimulated over the
conventional spontaneous RIXS signal into the small acceptance angle of the RIXS spectro-
meter. We also find that in solids both stimulated REXS and RIXS spectra contain con-
tributions from inelastic electron scattering processes, even for ultrashort 5 fs pulses.
Our results reveal the potential and caveats of the development of stimulated RIXS in
condensed matter.

Polyalanine molecules (PA) with an α-helix conformation have recently attracted a great deal of interest, as the propagation of electrons through the chiral backbone structure comes along with spin polarization of the transmitted electrons. By means of scanning tunneling microscopy and spectroscopy under ambient conditions, PA molecules adsorbed on surfaces of epitaxial magnetic Al2O3/Pt/Au/Co/Au nanostructures with perpendicular anisotropy were studied. Thereby, a correlation between the PA molecules ordering at the surface with the electron tunneling across this hybrid system as a function of the substrate magnetization orientation as well as the coverage density and helicity of the PA molecules was observed. The highest spin polarization values, P, were found for well-ordered self-assembled monolayers and with a defined chemical coupling of the molecules to the magnetic substrate surface, showing that the current-induced spin selectivity is a cooperative effect. Thereby, P deduced from the electron transmission along unoccupied molecular orbitals of the chiral molecules is larger as compared to values derived from the occupied molecular orbitals. Apparently, the larger orbital overlap results in a higher electron mobility, yielding a higher P value. By switching the magnetization direction of the Co layer, it was demonstrated that the non-spin-polarized STM can be used to study chiral molecules with a submolecular resolution, to detect properties of buried magnetic layers and to detect the spin polarization of the molecules from the change in the magnetoresistance of such hybrid structures.

We systematically analyze the influence of 5 nm thick metal interlayers inserted at the interface of several sets of different metal-dielectric systems to determine the parameters that most influence interface transport. Our results show that despite the similar Debye temperatures of Al2O3 and AlN substrates, the thermal boundary conductance measured for the Au/Al2O3 system with Ni and Cr interlayers is ∼2× and >3× higher than the corresponding Au/AlN system, respectively. We also show that for crystalline SiO2 (quartz) and Al2O3 substrates having highly dissimilar Debye temperature, the measured thermal boundary conductance between Al/Al2O3 and Al/SiO2 are similar in the presence of Ni and Cr interlayers. We suggest that comparing the maximum phonon frequency of the acoustic branches is a better parameter than the Debye temperature to predict the change in the thermal boundary conductance. We show that the electron–phonon coupling of the metallic interlayers also alters the heat transport pathways in a metal-dielectric system in a nontrivial way. Typically, interlayers with large electron–phonon coupling strength can increase the thermal boundary conductance by dragging electrons and phonons into equilibrium quickly. However, our results show that a Ta interlayer, having a high electron–phonon coupling, shows a low thermal boundary conductance due to the
poor phonon frequency overlap with the top Al layer. Our experimental work can be interpreted in the context of diffuse mismatch theory and can guide the selection of materials for thermal interface engineering.

Not only since the progressive reduction of structure sizes in modern micro- and nanotechnology, surface and interface effects have played an ever-increasing role and nowadays often dominate the behavior of entire systems. Therefore, understanding the nature of surface and interface effects and being able to fully control them is of fundamental importance, in particular in modern thin-film technology. In this study, it is revealed how Co/Pt multi-layer-based synthetic antiferromagnets (SAFs) with perpendicular magnetic anisotropy in the regime of dominating antiferromagnetic interlayer exchange can be employed to control the collective magnetic reversal via systemati-cally altering surface and interface effects. The specifically designed samples and experiments highlight the superior tunability of synthetic systems as compared to their intrinsic stoichiometric counterparts, where the antiferro-magnetism is directly tied to the indivisible discrete atomic nature and crystal structure of the materials. Thus, it is demonstrated that in SAFs, it becomes possible to energetically heal the broken magnetic symmetry at the surface, thereby enabling either on demand suppression or controlled enhancement of respective surface and interface effects, as demonstrated here in this study for the surface spin-flop and the exchange bias effect.

Intercalation of very long molecules into the structure of multi-layered graphene oxide was studied using example of 1-hexadecanol (C16), an alcohol molecule with 16 carbon atoms and length of about 22Å. Brodie graphite oxide (BGO) immersed in excess of liquid 1-hexadecanol just above the melting point shows expansion of c-unit cell parameter from ~6Å to ~48.76 Å forming a structure with two densely packed layers of C16 molecules in a vertical “stand up” orientation relative to graphene oxide planes (α-phase). Heating of the BGO-C16 α-phase in excess of C16 melt results in reversible phase transition into β-phase at 336-342K. The β-phase shows much smaller c-unit cell of 29.83 Å (363K). Analysis of data obtained using vacuum-driven evaporation of C16 from the β-phase and set of experiments with samples pre-mixed with different BGO:C16 proportions provides evidence for structure of β-phase consisting of five layers of C16 molecules in parallel to GO plane orientation. Therefore, the transition from α- to β- phase corresponds to change in orientation C16 molecules from vertical to parallel to GO planes and significant decrease in amount of intercalated solvent. Cooling of β-phase in absence of C16 melt is found to result in the formation of γ-phase with interlayer distance of ~26.5Å. This distance corresponds to one layer of C16 molecules intercalated in vertical relative to GO planes orientation. Finally, structures with one and two layers of C16 molecules parallel to GO planes were identified in samples with rather small initial loading of C16. Surprisingly rich variety of structures revealed in BGO-C16 system provides opportunities to create materials with precisely controlled GO inter-layer distance.

Extracellular matrix (ECM) provides various types of direct interactions with cells and a dynamic environment, which can be remodeled through different assembly/degradation mechanisms to adapt to different biological processes. Herein, through introducing polyphosphate-modified hyaluronic acid and bioactive glass (BG) nano-fibril into a self-assembled hydrogel system with peptide-polymer conjugate, we can realize many new ECM-like functions in a synthetic polymer network. The hydrogel network formation is mediated by coacervation, followed by a gradual transition of peptide structure from α-helix to β-sheet. The ECM-like hydrogels can be degraded through a number of orthogonal mechanisms, including treatments with protease, hyaluronidase, alkaline phosphatase, and calcium ion. As 2D coating, the ECM-like hydrogels can be used to modify the planar surface to promote the adhesion of mesenchymal stromal cells, or to coat the cell surface in a layer-by-layer fashion to shield the interaction with the substrate. As ECM-like hydrogels for 3D cell culture, the system is compatible with injection and cell encapsulation. Upon incorporating fragmented electrospun bioactive glass nano-fibril into the hydrogels, the synergetic effects of soft hydrogel and stiff reinforcement nanofibers on recapitulating ECM functions result in reduced cell circularity in 3D. Finally, by injecting the ECM-like hydrogels into mice, gradual degradations over a time period of one month and high biocompatibility have been shown in vivo. The contribution of complex network dynamics and hierarchical structures to cell-biomatrix interaction can be investigated multi-dimensionally, as many mechanisms are orthogonal to each other and can be regulated individually.

Stacking various two-dimensional (2D) materials in van der Waals (vdW) het- erostructures is a novel approach to design new systems, which can host alkali metal (AM) atoms to tune their electronic properties or store energy. Using state-of-the-art first-principles calculations, we systematically study the intercalation of the most wide- spread AMs (Li, Na, K) into a graphene/MoS2 heterostructure. Contrary to previous work on the intercalation of AMs into various heterostructures based on 2D materials, we consider not only single-, but also multi-layer configurations of AM atoms. We assess the intercalation energetics for various concentrations of AM atoms, calculate charge transfer from AM atoms to the host system, and show that although interca- lation of AMs as single layer is energetically preferable, multi-layer configurations can exist at high concentrations of AM atoms. We further demonstrate that the transition of the MoS2 layer from the H to T ′ phase is possible upon Li intercalation, but not Na or K. Our findings should help to better understand the behavior of heterostructures upon AM atom intercalation and may stimulate further experiments aimed at the tai- loring of heterostructure properties and increasing the capacity of anode materials in AM ion batteries.

Using first-principles and analytical potential atomistic simulations, we study the production of defects in epitaxial graphene on SiC upon ion irradiation for ion types and energies accessible in helium ion microscope. We focus on graphene-SiC systems consisting of the buffer (zero) graphene layer and SiC substrate, as well as one (monolayer) and two (bilayer) additional graphene layers. We calculate the probabilities for single, double and more complex vacancies to appear upon impacts of energetic ions in each graphene layer as functions of He and Ne ion energies, and compare the data to those obtained for the free standing graphene. The results indicate that the role of substrate is minimal for He-ion irradiation with energies above 5 keV, which can be associated with a low sputtering yield from this system upon ion irradiation, as compared to common Si/SiO2 substrate. In contrast, SiC substrate has a significant effect on defect production upon Ne-ion irradiation. Our results can serve as a guide to the experiments on ion irradiation of epitaxial graphene to choose the optimum ion beam parameters for defect-mediated engineering of such systems, e.g., for creating nucleation centers to grow other two-dimensional materials, such as h-BN, on top of the irradiated epitaxial graphene.

The rising production of lithium-ion batteries (LIBs) due to the introduction of electric mobility as well as stationary energy storage devices demands an efficient and sustainable waste man-agement scheme for legislative, economic and ecologic reasons. One crucial part of the recycling of end-of-life (EOL) LIBs is mechanical processes, which generate material fractions for the pro-duction of new batteries or further metallurgical refining. In the context of safe and efficient processing of electric vehicles’ LIBs, crushing is usually applied as a first process step to open at least the battery cell and liberate the cell components. However, the cell opening method used requires a specific pretreatment to overcome the LIB’s hazard potentials. Therefore, the depend-ence on pretreatment and crushing is investigated in this contribution. For this, the energy input for liberation is determined and compared for different recycling strategies with respect to dis-mantling depth and depollution temperatures. Furthermore, the respective crushing product is analyzed regarding granulometric properties, material composition and liberation and decoat-ing behaviour depending on the pretreatment and grid size of the crushing equipment. Finer particles and components are generated with dried cells. Pyrolysis of cells, as well as high dis-mantling depths, do not allow to draw exact conclusions. The calculated and measured mass-specific mechanical energy input of different dismantling depths shows good accuracy. Consequently, trends for a successful separation strategy of the subsequent classifying and sort-ing processes are revealed, and recommendations for the liberation of LIBs are derived.

Exploiting the strong electromagnetic fields that can be supported by a plasma, high-power laser driven compact plasma accelerators enable generation of short, high-intensity pulses of high energy ions with special beam properties. These accelerators promise to expand the portfolio of conventional machines in many application areas. The maturation of laser driven ion accelerators from physics experiments to turn-key sources for these applications will rely on breakthroughs in both, generated beam parameters (kinetic energy, flux), as well as increased scrutiny on reproducibility, robustness and scalability to high repetition rate.
Recent developments at the high-power laser facility DRACO-PW enabled the production of polychromatic proton beams with unprecedented stability [1]. This allowed the first in vivo radiobiological study to be conducted using a laser-driven proton source [2]. Yet, the ability to achieve energies beyond the 100 MeV frontier is essential for many applications and a matter of ongoing research, mainly addressed by exploring advanced acceleration schemes like the relativistically induced transparency regime.
In this talk we report on experimental proton acceleration studies at the onset of relativistic transparency using linearly polarized laser pulses with peak intensities of 6x21 W/cm2 focused on thin, pre-expanded plastic foils. Combined hydrodynamic and 3D particle-in-cell simulations helped to identify the most promising target parameter range matched to the carefully measured prevailing laser contrast conditions. In a nutshell, the ultra-intense femtosecond pulse interaction induces large accelerating gradients and energy gain dominantly arising from significant space charge fields due to electron expulsion from the relativistic transparent target core followed by weaker post-acceleration in diffuse sheath fields at later times. A complex suite of particle and optical diagnostics allowed characterization of spatial and spectral proton beam parameters and the stability of the regime of best acceleration performance, yielding cut-off energies larger than 100 MeV in the best shots.

Exploiting the strong electromagnetic fields that can be supported by a plasma, high-power laser driven compact plasma accelerators enable generation of short, high-intensity pulses of high energy ions with special beam properties. These accelerators promise to expand the portfolio of conventional machines in many application areas. The maturation of laser driven ion accelerators from physics experiments to turn-key sources for these applications will rely on breakthroughs in both, generated beam parameters (kinetic energy, flux), as well as increased scrutiny on reproducibility, robustness and scalability to high repetition rate.
Recent developments at the high-power laser facility DRACO-PW enabled the production of polychromatic proton beams with unprecedented stability [1]. This allowed the first in vivo radiobiological study to be conducted using a laser-driven proton source [2]. Yet, the ability to achieve energies beyond the 100 MeV frontier is essential for many applications and a matter of ongoing research, mainly addressed by exploring advanced acceleration schemes like the relativistically induced transparency regime.
In this talk we report on experimental proton acceleration studies at the onset of relativistic transparency using linearly polarized laser pulses with peak intensities of 6x21 W/cm2 focused on thin, pre-expanded plastic foils. Combined hydrodynamic and 3D particle-in-cell simulations helped to identify the most promising target parameter range matched to the carefully measured prevailing laser contrast conditions. In a nutshell, the ultra-intense femtosecond pulse interaction induces large accelerating gradients and energy gain dominantly arising from significant space charge fields due to electron expulsion from the relativistic transparent target core followed by weaker post-acceleration in diffuse sheath fields at later times. A complex suite of particle and optical diagnostics allowed characterization of spatial and spectral proton beam parameters and the stability of the regime of best acceleration performance, yielding cut-off energies larger than 100 MeV in the best shots.

An energy storage (ES) system is an economical and reliable technology that plays a
predominant role in making the renewable energy sector sustainable. Integration of ES with
wind and solar plants provides solution to problem of grid instability caused by to fluctuating
power output. The Thermal Energy Storage (TES) system is simple and has low environmental
and social impacts compared to other ES technologies like batteries, pumped hydro,
compressed air and chemical storage. However, application of a TES at high temperature is
quite unexplored and has a limited deployment globally.
Solid sensible TES (STES) stores excess electricity in form of sensible heat, the solid medium
is directly electrical heated or indirectly heated using heat transfer fluids (HTF). In STES
systems, no phase change nor chemical reactions involved. Hence, it is simple, easy to
maintain and the cost of construction materials is low. The foresaid advantages makes it
suitable for high temperature applications provided the solid material selected exhibits higher
temperature stability.
The poster will highlight the thermal performance of STES for 10 MWth power output over 24
hours, resulting in a storage capacity of 240 MWhth at high temperature of 800 °C. The
candidates of investigation are most commonly used solid materials, like high temperature
ceramic, high temperature concrete, firebricks, alferrock as well as vitrified flyash and as HTFs
Air, He, CO2 and N2 were studied. The influence of geometry, flow rate, heat transfer surface
area and solid material configuration in storage tank on the thermodynamics of TES system
cannot be ignored. Therefore, different STES designs were also included for assessment in
this research work.
To investigate the thermal performance of a STES system in terms of all the above-mentioned
candidates, a One-dimensional model will be developed in MATLAB and validated with data
available in literature. Based on results, the performance parameters like solid temperature
during charging/discharging cycle as well as overall thermal efficiency are evaluated. In addition, the economical assessment of different TES designs and materials can be estimated in €/MWhth.

The talk will start with an overview on the working principle of the all-liquid Na-Zn molten salt battery. Thereafter, various fluid dynamic effects, which might appear in such cells, will be discussed.

A single qutrit with transitions selectively driven by weakly-coupled reservoirs can implement one of the world's smallest refrigerators. We analyze the performance of N such fridges that are collectively coupled to the reservoirs. We observe a quantum boost, manifest in a quadratic scaling of the steady-state cooling current with N. As N grows further, the scaling reduces to linear, since the transitions responsible for the quantum boost become energetically unfavorable. Fine-tuned inter-qutrit interactions may be used to maintain the quantum boost for all N and also for not-perfectly collective scenarios.

Cutting fluids are usually applied during milling to reduce the friction and to protect the tool and the material from corrosion. These fluids are associated with toxicity and environmental problems. Moreover, the waste management of cutting fluids entails large expenses. The need to reduce cutting fluids has fostered the use of alternative coolants such as supercritical (sc) CO₂, alone or with minimum quantity lubrication (MQL). sc CO₂ and sc CO₂ + MQL coolants have been studied for face milling of a cold worked (CW) AISI 316L stainless steel (SS), evaluating their effect on the residual stresses generated in the surface, in the outermost microstructure of this material, and the corrosion performance. Furthermore, they are compared with those caused by traditional face milling and with a manually ground-generated surface. Ultrafine grain (UFG) layers of about 1 μm and passive layers (of similar chemical compositions) are identified for all the surfaces under study. The three milling processes under study generate a deformation layer under the UFG layer that does not appear below ground surfaces. Moreover, the preexistent compressive stresses created by the CW process change into tensile, being higher for the alternative green machining processes than for the traditional one. The probability of undergoing pitting (studied with cyclic polarization curves) appears to be linked to the nature and structure of the passive layer (characterized by Auger spectroscopy and Mott–Schottky analyses, respectively). Electrochemical impedance spectroscopy studies also confirm similar electrochemical performances for all analyzed surfaces. The active-to-passive transitions of the SS, which have been characterized by electrochemical potentiodynamic reactivation tests, appear to be related to the stresses and deformation state of the deformed layers. Passivation on the alloy in acid media appears to be favored after the sc CO₂ and sc CO₂ + MQL alternative milling processes than after traditional face milling and grinding.

Motion sensing is the primary task in numerous disciplines including industrial robotics, prosthetics, virtual and augmented reality appliances. In rigid electronics, rotations, displacements and vibrations are typically monitored using magnetic field sensors. Here, we will discuss the fabrication of flexible, stretchable and printable magnetoelectronic devices. The technology platform relies on high-performance magnetoresistive and Hall effect sensors deposited or printed on ultrathin polymeric foils. These skin conformal flexible and printable magnetosensitive elements enable touchless interactivity with our surroundings based on the interaction with magnetic fields, which is relevant for smart skins, soft robotics and human-machine interfaces.

The widespread adoption of gallium nitride (GaN) in radiation-hard semiconductor devices relies on a comprehensive understanding of its response to strongly ionizing radiation. Despite being widely acclaimed for its high radiation resistance, the exact effects induced by ionization are still hard to predict due to the complex phase-transition diagrams and defect creation-annihilation dynamics associated with group-III nitrides. Here, Two-Temperature Model, Molecular Dynamics simulations and Transmission Electron Microscopy, are employed to study the interaction of Swift Heavy Ions with GaN at the atomic level. The simulations reveal a high propensity of GaN to recrystallize the region melted by the impinging ion leading to high thresholds for permanent track formation. Although the effect exists in all studied electronic energy loss regimes, its efficiency is reduced with increasing electronic energy loss, in particular when there is dissociation of the material and subsequent formation of N 2 bubbles. The recrystallization is also hampered near the surface where voids and pits are prominent. The exceptional agreement between the simulated and experimental results establishes the applicability of the model to examine the entire electronic energy loss spectrum. Furthermore, the model supports an empirical relation between the interaction cross sections (namely for melting and amorphization) and the electronic energy loss.

Personnel scheduling in organizations can be disrupted by unforeseen events that require efficient planning. A recent example is the COVID-19 pandemic that disrupted global operations, compromising people's health and safety. Many organizations were forced to transition to full remote work to prevent the spread of the virus and ensure employee safety. Although working entirely remotely is effective for some organizations, others must balance workplace occupancy and infection risk to keep their operations functioning efficiently despite a global health crisis. We address this issue by developing a days-off scheduling model that captures employees' interactions through the underlying contact network. To solve the problem, we propose a Mixed Integer Linear Programming model considering a Microscopic Markov Chain Approach to determine the probability of infection in a contact network that mimics the employees' interactions. The model determines, during a given planning period, the optimal staffing mix to maximize occupancy while minimizing the risk of infection in the presence of testing protocols. We conduct sensitivity analysis to assess the approach's robustness while considering different contact networks and testing strategies. Through extensive computational analysis, we show that the degree of contact among employees is not the sole factor to consider when defining personnel scheduling policies during disease outbreaks. The decision-maker must balance the employee allocation with tailored testing interventions based on management's priorities to mitigate the effects while ensuring the desired occupancy at a lower risk.

Using a fast and accurate neural network potential, we are able to systematically
explore the energy landscape of large unit cells of bulk magnesium oxide with the
minima hopping method. The potential is trained with a focus on the near-
stoichiometric compositions, in particular on suboxides, i.e., Mg x O 1−x with 0.50 < x <
0.60. Our extensive exploration demonstrates that for bulk stoichiometric
compounds, there are several new low-energy rock-salt-like structures in which Mg
atoms are octahedrally six-coordinated and form trigonal prismatic motifs with
different stacking sequences.
Furthermore, we find a dense spectrum of novel nonstoichiometric crystal phases of
Mg x O 1−x for each composition of x. These structures are mostly similar to the rock-salt
structure with octahedral coordination and five-coordinated Mg atoms. Due to the
removal of one oxygen atom, the energy landscape becomes more glass-like with
oxygen-vacancy type structures that all lie very close to each other energetically. For
the same number of magnesium and oxygen atoms, our oxygen-deficient structures
are lower in energy if the vacancies are aligned along lines or planes than rock-salt
structures with randomly distributed oxygen vacancies. We also found the putative
global minima configurations for each composition of the nonstoichiometric suboxide
structures. These structures are predominantly composed of MgO(111) layers of the
rock-salt structure which are terminated with Mg atoms at the top and bottom and
are stacked in different sequences along the z direction. Like for other materials,
these Magnéli-type phases have properties that differ considerably from their
stoichiometric counterparts such as high electrical conductivity

Rohstoffkreisläufe schließen als wesentlicher Faktor für den Klimaschutz - wo sind die Grenzen des Recyclings? Können wir bei hoher Recyclingquote auch auf Bergbau verzichten? Unsere Herausforderungen erklärt an den Beispielen des Handys und der Elektromobilität.

As has been stated e.g. in Meisel et al. (2022) that the mineralogical composition of a certain sample
does have an influence on the analytical geochemical results obtained. Prior to the start of the analytical
geochemical studies, an approximate idea of the mineralogical composition of the sample to be
analyzed should be available. This helps to select the digestion method and the methods to be used
(matrix effect).
We chose 14 samples from different GeoPT rounds representing a wide spectrum of rock composition
for a detailed quantitative X-ray diffraction (XRD) study.
Based on the determined quantitative mineralogical composition, an estimation of the chemical
composition can be made. This is achieved by a back calculation using the mineral chemistry of the
identified mineral phases. The Profex/BGMN software package (Doebelin & Kleeberg, 2015)
automatically calculates these values. These data can be directly compared with the results of a GeoPT
round robin.
It must be taken into account that the sample preparation for a GeoPT round robin is not ideal for
quantitative XRD investigations and artifacts must be expected. XRD slightly underestimates e.g.
SiO2-values (Fig. 1). This is mainly due to an overgrinding effect, where quartz forms an
“amorphization” layer at the surface (O’Connor & Chang, 1986).

The GeoPT programme (IAG, 2020) is a valuable tool that allows geochemical laboratories to test their routine analytical performance and, if necessary, undertake remedial action where errors of inappropriate magnitude are detected. During the past 25 years and 63 rounds so far, the GeoPT programme has provided a great variety of rock samples for the benefit of participants. While the GeoPT programme solely focuses on geochemical composition data, it is well known that the mineralogical content of geochemical materials is also of importance to analysts, to researchers and to industrialists (e.g. Meisel et al. 2022). It has long been known that the so-called mineralogical effect can influence the quantitative outcomes of XRF measurements made on pressed pellets. In addition, wet chemical techniques may also suffer from incomplete digestion when resistant minerals are present, unless a rigorous multi acid attack or a combination of fusion and dissolution are employed. The mineralogical content of geological materials is, therefore, important but is not implicitly assessed in the GeoPT programme. Is there a need, therefore, for a dedicated mineralogical proficiency testing programme (MinPT?)?

To our knowledge, there is only one regular mineralogical round robin interlaboratory test programme – the biennial Reynolds Cup (Raven & Self, 2017), which focuses on clay minerals and follows a slightly different approach as the composition of the material is known to the organizers at the outset.

The reason for this interactive poster is to investigate the need for a mineralogical interlaboratory round robin test linked to the GeoPT proficiency testing programme. The idea is that essentially the same material would be distributed in a simultaneous GeoPT and mineralogical test round. Special preparation procedures will be required to ensure that the test material is suitable for both geochemical and mineralogical laboratories operating techniques such as X-ray diffraction, automated mineralogy (MLA, QUEMSCAN, TIMA, etc.) and others. Quantitative mineralogical data from this round robin test would be assessed where possible, using the same well-established GeoPT procedures and providing participating laboratories with personalized performance data. Furthermore, a direct comparison with bulk compositional data from the complementary GeoPT round would permit further insights into analytical performance. It is important to note that there is no expectation that participating laboratories would have to participate in both the GeoPT and mineralogical rounds, but participation in both would be welcomed.

With the help of this interactive poster, we would like to ask delegates for indications of their general interest in participating in a combined mineralogical/geochemical test of proficiency based on effectively the same test materials.

References:

Meisel, T. C., Webb, P. C., & Rachetti, A. (2022). Highlights from 25 Years of the Geo PT Programme: What Can be Learnt for the Advancement of Geoanalysis. Geostandards and Geoanalytical Research.
Raven, M. D., & Self, P. G. (2017). Outcomes of 12 years of the Reynolds Cup quantitative mineral analysis round robin. Clays and Clay Minerals, 65(2), 122-134.
IAG (2020). Protocol for the operation of the GeoPT Proficiency testing scheme. International Association of Geoanalysts (Keyworth, UK), 18pp. http://www.geoanalyst.org/wp-content/uploads/2020/07/GeoPT-revised-protocol-2020.pdf.

Nachhaltiger Umgang mit natürlichen Rohstoffquellen ist eine der drängendsten Aufgaben unserer Gesellschaft. Das Konzept dazu ist die sogn. Kreislaufwirtschaft. Damit verbunden sind Worte wie Nachhaltigkeit und Recycling. Doch alles was recycled wird, muss erst durch Bergbau gewonnen werden. Wo sind die Grenzen des Recyclings? Können wir bei hoher Recyclingquote auch auf Bergbau verzichten?

Jeder von uns hat ein Handy und die Anzahl der Elektroautos nimmt zu. Dazu braucht man Rohstoffe, die zuvor in diesen Mengen nicht benötigt wurden. Die Herausforderungen für die Gewinnung der Rohstoffe werden an Beispielen des Handys und der Elektromobilität erklärt.

The cabonatite-hosted Namxe rare earth element (REE) deposit in northern Vietnam has a total rare earth oxide (TREO) content of up to 2 wt% which is mainly hosted by parasite in the southern part of the deposit. Detailed mineralogical investigation of the rather complex mineralization revealed that parisite occurs in two geochemical varieties with slightly differing REE2O3/CaO ratios (5.8 ±0.2 vs. 6.8 ±0.35). Parisite occurs in dykes together with carbonates (ankerite, calcite) and barite and is often intergrown with fine-grained (sub 100µm size fraction) barite-celestine group minerals. The recognition of remnants of corroded bastnaesite suggest that REE enrichment is a result of a multi-stage process involving Sr- and CO3-rich fluids with mantle signature (δ13C values of -6.8 ‰ to -2.89 ‰) with no or little additional REE input.
We applied state-of-the-art techniques to propose a possible processing route of the ore, including experiments using sensor-sorting, selective comminution, magnetic separation (HIMS and WHIMS) and froth flotation. Sensor sorting turned out to be quite efficient as the basaltic host rock can be separated from the dyke material, resulting in a mass reduction of about 30% and a REE loss of less than 2%. Selective comminution experiments revealed similar results with the rejection of 27% of barren material and a slightly higher loss of REE (3.5%). Two step froth flotation of a model blend led to a concentrate with >40% TREO content.

The influence of non-interacting Kohn–Sham Hamiltonian on the non-self consistent GW(G0W0) quasiparticle gap and Bethe–Salpeter-equation (BSE) optical spectra of anatase TiO2 is systematically evaluated. G0W0 and BSE calculations are carried out starting with HSE06 (Heyd–Scuseria–Ernzerhof) type functionals containing 20%, 25% and 30% exact Hartree–Fock exchange. The results are also compared against G0W0 + BSE calculations starting from semi-local (PBE) functionals. Our results indicate that the G0W0 and BSE calculations of anatase TiO2 depend critically on the mean-field starting point, wherein its dependence is mainly introduced through the dielectric screening evaluated at the intermediate G0W0.We find that the band dispersion, density of states, and consequently the oscillator strengths of optical excitation and spatial localization of excitons are insensitive to the starting points while the quasiparticle gap, optical gap and exciton binding energies are strongly affected. G0W0 quasiparticle gap of anatase TiO2 computed over hybrid functional starting points is typically overestimated compared to measured values. However, by varying the amount of exact exchange, the dielectric screening can be tuned, and thus the quasiparticle gap. Exciton binding energy is shown to increase in proportion to the increase of the amount of exact exchange. A simple extrapolation of the calculated data leads to the exact match with the recently measured value with 13% of the exact exchange. Systematic analysis of G0W0 + BSE calculation starting from screened hybrid functionals provided in this study forms a reference for all such future calculations of pristine anatase TiO2 and its derivatives.

Open-shell systems are normally described using spin density
functional theory (SDFT) rather than regular DFT, due to spinpolarised approximations appearing to yield superior results
for exchange-correlation (xc) energies. To address the seemingly poorer (xc) energies obtained via DFT approximations
(DFAs), we show that correcting for a qualitative error in the
DFT description for open-shell systems, one obtains results
with SDFT accuracy. Furthermore, in the absence of external magnetic fields, both DFT and SDFT should reduce to
the same limit. We provide the link between these two theories, demonstrating how the regular KS equations of SDFT
reduce to a new (generalised) set of KS equations for DFT in
this limit. We also extend these ideas to ensembles of varying
electron number, obtaining a finite derivative discontinuity for
commonly used (semi-)local DFAs.

Molecular diffusion is an important transport mechanism for radionuclide migration in low-permeable argillaceous host rock such as Opalinus Clay (OPA). In this study, the influence of sedimentary and diagenetic heterogeneity on heterogeneous diffusion in sandy facies of OPA (SF-OPA) from lamina scale to drill core scale is investigated using an upscaling workflow to model diffusive transport from the pore scale to the core scale. Our numerical results based on the simplified structural model show fast diffusion fronts in clay laminae (7 mm displacement after 6 days of diffusion) and slow diffusion fronts in carbonate lenses and sand laminae (4 mm displacement after 6 days of diffusion), demonstrating the endmembers of heterogeneous diffusion patterns in SF-OPA. Moreover, our results show that the diffusion fronts begin to homogenize after 22 days of diffusion with the specific influence of carbonate lenses (here: length = 1 cm, thickness = 3 mm). This example illustrates how material heterogeneities affect heterogeneous diffusion on a small temporal and spatial scale. The sensitivity studies show that the diffusion length and homogenization time increase by up to 190% when the length and thickness of the carbonate lenses are doubled. Using four compositional endmembers, we show the generalized diffusion behavior to demonstrate the influence of thin laminae and thick layers as well as dispersed small and large diagenetic concretions on the homogeneity of diffusion. These results demonstrate that the geometry of sedimentary and diagenetic material and the subfacies composition are the controlling factors for quantifying diffusion length and homogenization time. This study provides quantitative constraints on the temporal and spatial evolution of heterogeneous diffusion at the core scale. This quantitatively improves the predictability of radionuclide migration in host rocks as a function of compositional and pore network-specific parameters.

The study of warm dense matter (WDM) is critical to our understanding of many interesting scientific and technological phenomena, in particular various astrophysical applications, and inertial confinement fusion. To develop accurate models for WDM, one has to account for the quantum behaviour of electrons (and sometimes nuclei too) across a wide range of temperatures and densities, which presents a challenge for established modelling techniques. In our poster, we introduce the concept of an average-atom model, which accounts (partially) for these quantum interactions in a computationally efficient way. We show some example applications of average-atom models, to demonstrate their usefulness in the WDM regime. We also present atoMEC: an average-atom code for matter under extreme conditions, which is open-source and written in Python.

Average-atom models are an essential tool in modelling the warm dense matter regime, because they can be used to compute key quantities, such as equation-of-state data, for a fraction of the computational cost of higher-fidelity simulations such as DFT-MD. However, a variety of different models exist, and it is important to benchmark these models to understand their limitations and expected accuracy under various conditions. In this presentation, we focus on two key properties in WDM — the mean ionization state and pressure — for a range of materials, densities and temperatures. Through comparison with higher-fidelity simulations and experimental results, we probe the accuracy of an average-atom model, considering various choices of approximation within that model. We demonstrate a well-chosen average-atom model, under the right conditions, can yield close agreement with these benchmarks.

Modelling the behaviour of materials under warm dense matter (WDM) conditions is important to our understanding of various astrophysical phenomena and inertial confinement fusion (for example). Finite-temperature Kohn--Sham density-functional theory (KS-DFT) can be applied to study materials exposed to WDM conditions --- temperatures of around 1-1000 eV and densities from 10^-2 to 10^4 g/cm3 --- but the usual KS-DFT approach for periodic systems becomes computationally intractable at higher temperatures. In this presentation, we first derive a density-functional average-atom model --- which reduces the full many-body system of electrons and nuclei to a single atom immersed in a plasma --- from first principles. Using this model, we investigate the behaviour of the mean ionization state and pressure (key properties in WDM) for a range of materials, densities and temperatures. Through comparison with higher fidelity simulations and experimental results, we demonstrate that computationally light average-atom models yield accurate results under the right conditions and approximations.

Warm dense matter (WDM) is an exotic phase of matter which lies at the intersection between the condensed-matter and plasma physics communities. Understanding the behaviour of materials under WDM conditions is important for nuclear fusion research, and astro and planetary physics. Average-atom models are widely-used in WDM research, but the large number of models available and lack of open-source availability makes them hard to understand and use. In this talk, we first derive an average-atom model from first principles, then introduce our Python library atoMEC, which aims to facilitate development and comparison of average-atom models.

Average-atom models are an important tool in studying matter under extreme conditions, such as those conditions experienced in planetary cores, brown and white dwarfs, and during inertial confinement fusion. In the right context, average-atom models can yield results with similar accuracy to simulations which require orders of magnitude more computing time, and thus can greatly reduce financial and environmental costs. Unfortunately, due to the wide range of possible models and approximations, and the lack of open-source codes, average-atom models can at times appear inaccessible. In this paper, we present our open-source average-atom code, atoMEC. We explain the aims and structure of atoMEC to illuminate the different stages and options in an average-atom calculation, and to facilitate community contributions. We also discuss the use of various open-source Python packages in atoMEC, which have expedited its development.

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 under Earth-core conditions calls for sophisticated theoretical methods that can support diagnostics. We compute the 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 (TDDFT).
We are working on Spectral Neighbor Analysis Potential (SNAP) machine-learning potential for large-scale molecular dynamics simulations including coupling spin-lattice dynamics. The generated models can be used to simulate phenomena in iron, such as the interplay of phonon, and magnetic contributions to the thermal conductivity, or to perform high-pressure shock compression simulations.

Background. Glioblastoma (GBM) is a fast-growing primary brain tumor characterized by high
invasiveness and resistance. This results in poor patient survival. Resistance is caused by
many factors, including cell-extracellular matrix (ECM) interactions. Here, we addressed the
role of adhesion protein integrin α2, which we identified in a high-throughput screen for novel
potential targets in GBM cells treated with standard therapy consisting of temozolomide (TMZ)
and radiation.
Methods. In our study, we used a range of primary/stem-like and established GBM cell models
in vitro and in vivo. To identify regulatory mechanisms, we employed high-throughput kinome
profiling, Western blotting, immunofluorescence staining, reporter and activity assays.
Results. Our data showed that integrin α2 is overexpressed in GBM compared to normal brain
and, that its deletion causes radiochemosensitization. Similarly, invasion and adhesion were
significantly reduced in TMZ-irradiated GBM cell models. Furthermore, we found that integrin
α2-knockdown impairs proliferation of GBM cells without affecting DNA damage repair. At the
mechanistic level, we found that integrin α2 affects the activity of activating transcription factor
1 (ATF1) and modulates the expression of extracellular signal-regulated kinase 1 (ERK1)
regulated by extracellular signals. Finally, we demonstrated that integrin α2-deficiency inhibits
tumor growth and thereby prolongs survival of mice with orthotopically growing GBM
xenografts.
Conclusions. Taken together our data suggest that integrin α2 may be a promising target to
overcome GBM resistance to radio- and chemotherapy. Thus, it would be worth evaluating
how efficient and safe the adjuvant use of integrin α2 inhibitors is to standard
radio(chemo)therapy in GBM.

Several properties of hydrogen in the solid, liquid, and metallic liquid are investigated for different xc functionals

Polymethylmethacrylate (PMMA) removal during septic total joint arthroplasty revisionis associated with a high fracture and perforation risk. Ultrasonic cement removal isconsidered a bone‐preserving technique. Currently, there is still a lack of sound data onefficacy as it is difficult to detect smaller residues with reasonable technical effort.However, incomplete removal is associated with the risk of biofilm coverage of theresidue. Therefore, the study aimed to investigate the efficiency of ultrasonic‐basedPMMA removal in a human cadaver model. The femoral components of a total hip and atotal knee prosthesis were implanted in two cadaver femoral canals by 3rd generationcement fixation technique. Implants were then removed. Cement mantle extraction wasperformed with the OSCAR‐3‐System ultrasonic system (Orthofix®). Quantitativeanalysis of cement residues was carried out with dual‐energy and microcomputertomography. With a 20 μm resolution, in vitro microcomputer tomography visualized tiniest PMMA residues. For clinical use, dual‐energy computer tomography tissuedecomposition with 0.75 mm resolution is suitable. With ultrasound, more than 99% ofPMMA was removed. Seven hundred thirty‐four residues with a mean volume of0.40 ± 4.95 mm3were identified with only 4 exceeding 1 cm in length in at least oneaxis. Ultrasonic cement removal of PMMA was almost complete and can therefore beconsidered a highly effective technique.For the first time, PMMA residues in thesub‐millimetre range were detected by computer tomography. Clinical implications ofthe small remaining PMMA fraction on the eradication rate of periprosthetic jointinfection warrants further investigations.

Ultrathin asymmetrically sandwiched ferromagnetic films support fast moving chiral magnetic domain walls and skyrmions [1,2]. This paves the way to the realization of prospective racetrack memory concept, the performance of which is determined by the static and dynamic micromagnetic parameters [3]. The necessity of having strong Dzyaloshinskii-Moriya interactions (DMI) and perpendicular magnetic anisotropy requires the utilization of ultrathin magnetic (~1 nm) layers, which compromized structural quality, that substantially enhances the magnetic damping for non-collinear magnetic textures.

Here, we present the experimental and theoretical analysis of ultrathin Co films with asymmetric interfaces //CrO x /Co/Pt and estimation of their micromagnetic parameters based on the analysis of the temperature dependence of magnetization as well as imaging of the morphology of magnetic domain walls (DWs) in stripes. Namely, we show that the best fit to the magnetometry data up to room temperature is obtained within a quasi-2D model, accounting for the lowest transversal magnons [4]. The fit provides access to the exchange constant in asymmetric stackes which is found to be about 1 order of magnitude smaller compared to the bulk Co. The experimentally observed tilt of magnetic domain walls in stripes in statics can be explained based on two models: (I) A unidirectional tilt could appear in equilibrium as a result of the competition between the DMI and additional in-plane easy-axis anisotropy, which breaks the symmetry of the magnetic texture and introduce tilts [5]. (II) A static DW tilt could appear due to the spatial variation of magnetic parameters, which introduce pinning centers for moving tilted DWs driven by magnetic field and can fix them at remanence [6]. We found that the second model is in line with the experimental observations and allows to determine self-consistently the DW damping parameter and DMI constant for the particular layer stack. The DW damping is found to be about 0.1 and explained by the enhanced longitudinal relaxation mechanism. The latter is shown to much stronger tan the standard transversal relaxation and can be even stronger than the spin pumping contribution for the case of ultrathin ferromagnetic films [7].

References:

[1] N. Nagaosa and Y. Tokura, “Topological properties and dynamics of magnetic skyrmions”, Nat. Nanotechnol. 8, 899 (2013).
[2] A. Fert, N. Reyren, and V. Cros, “Magnetic skyrmions: advances in physics and potential applications”, Nat. Rev. Mater. 2, 17031 (2017).
[3] C. Garg, S.-H. Yang, T. Phung, A. Pushp and S. S. P. Parkin, “Dramatic influence of curvature of nanowire on chiral domain wall velocity”, Sci. Adv. 3, e1602804 (2017).
[4] I. A. Yastremsky, O. M. Volkov, M. Kopte, T. Kosub, S. Stienen, K. Lenz, J. Lindner, J. Fassbender, B. A. Ivanov and D. Makarov, “Thermodynamics and Exchange Sti ff ness of Asymmetrically Sandwiched Ultrathin Ferromagnetic Films with Perpendicular Anisotropy”, Phys. Rev. Appl. 12, 064038 (2019).
[5] O. V. Pylypovskyi, V. P. Kravchuk, O. M. Volkov, J. Fassbender, D. D. Sheka and D. Makarov, “Unidirectional tilt of domain walls in equilibrium in biaxial stripes with Dzyaloshinskii–Moriya interaction”, J. Phys. D: Appl. Phys. 53, 395003 (2020).
[6] O. M. Volkov, F. Kronast, C. Abert, E. Se. Oliveros Mata, T. Kosub, P. Makushko, D. Erb, O. V. Pylypovskyi, M.-A. Mawass, D. Sheka, S. Zhou, J. Fassbender and D. Makarov, “Domain-Wall Damping in Ultrathin Nanostripes with Dzyaloshinskii-Moriya Interaction”, Phys. Rev. Appl. 15, 034038 (2021).
[7] I. A. Yastremsky, J. Fassbender, B. A. Ivanov, and D. Makarov, “Enhanced Longitudinal Relaxation of Magnetic Solitons in Ultrathin Films”, Phys. Rev. Appl. 17, L061002 (2022).

The interplay between geometry and topology of the order parameter is crucial properties in soft and condensed matter physics, including cell membranes [1], nematic crystals [2,3], superfluids [4], semiconductors [5], ferromagnets [6] and superconductors [7]. Until recently, in the case of magentism, the influence of the geometry on the magnetization vector fields was addressed primarily by the design of the sample boundaries, aiming to tailor anisotropy of the samples. With the development of novel fabrication techniques allowing to realize complex 3D architectures, not only boundary effects, but also local curvatures can be addressed rigorously for the case of ferromagnets and antiferromagnets. It is shown that curvature governs the appearance of geometry-induced chiral and anisotropic responses [6-8].

Here we provide experimental confirmations of the existence of local and non-local curvature-induced chiral interactions of the exchange and magnetostatic origin in conventional soft ferromagnetic materials. Namely, we will present the experimental validation of the appearance of exchange-driven Dzyaloshinskii-Moriya interaction interaction (DMI, local effect) for the case of conventional achiral yet geometrically curved magnetic materials [9,10]. This curvature induced DMI is predicted to stabilize skyrmions [11] and skyrmionium states [12]. Furthermore, we will address the impact of nonlocal magnetostatic interaction on the properties of curvilinear ferromagnets, which enables the stabilization of topological magnetic textures [13,14], realization of high-speed magnetic racetracks [15] and curvature-induced asymmetric spin-wave dispersions in nanotubes [16]. Furthermore, symmetry analysis demonstrates the possibility to generate a fundamentally new chiral symmetry breaking effect, which is essentially nonlocal [13]. Thus, geometric curvature of thin films and nanowires is envisioned as a toolbox to create artificial chiral nanostructures from achiral magnetic materials.

References:

[1] H. T. McMahon and J. L. Gallop “Membrane curvature and mechanisms of dynamic cell membrane remodelling”, Nature 438, 590 (2005).
[2] T. Lopez-Leon, V. Koning, K. B. S. Devaiah, V. Vitelli and A. Fernandez-Nieves, “Frustrated nematic order in spherical geometries”, Nature Physics 7, 391 (2011).
[3] G. Napoli, O. V. Pylypovskyi, D. D. Sheka and L. Vergori, “Nematic shells: new insights in topology- and curvature-induced e ff ects”, Soft Matter 17, 10322-10333 (2021).
[4] H. Kuratsuji, “Stochastic theory of quantum vortex on a sphere”, Phys. Rev. E 85, 031150 (2012).
[5] C. Ortix, Phys, “Quantum mechanics of a spin-orbit coupled electron constrained to a space curve”, Phys. Rev. B 91, 245412 (2015).
[6] D. D. Sheka, O. V. Pylypovskyi, O. M. Volkov, K. V. Yershov, V. P. Kravchuk and D. Makarov, “Fundamentals of Curvilinear Ferromagnetism: Statics and Dynamics of Geometrically Curved Wires and Narrow Ribbons”, Small 18, 2105219 (2022).
[7] D. Makarov, O. M. Volkov, A. Kakay, O. V. Pylypovskyi, B. Budinská and O. V. Dobrovolskiy, “New Dimension in Magnetism and Superconductivity: 3D and Curvilinear Nanoarchitectures”, Adv. Mater. 34, 2101758 (2022).
[8] Y. Gaididei, V. P. Kravchuk and D. D. Sheka, “Curvature Effects in Thin Magnetic Shells”, Phys. Rev. Lett. 112, 257203 (2014).
[9] O. M. Volkov, D. D. Sheka, Y. Gaididei, V. P. Kravchuk, U. K. Rößler, J. Fassbender and D. Makarov, ”Mesoscale Dzyaloshinskii-Moriya interaction: geometrical tailoring of the magnetochirality”, Sci. Rep. 8, 866 (2018).
[10] O. M. Volkov, A. Kákay, F. Kronast, I. Mönch, M.-A. Mawass, J. Fassbender and D. Makarov, “Experimental observation of exchange-driven chiral effects in curvilinear magnetism”, Phys. Rev. Lett. 123, 077201 (2019).
[11] V. P. Kravchuk, D. D. Sheka, A. Kákay, O. M. Volkov, U. K. Rößler, J. van den Brink, D. Makarov and Y. Gaididei, “Multiplet of Skyrmion States on a Curvilinear Defect: Reconfigurable Skyrmion Lattices”, Phys. Rev. Lett. 120, 067201 (2018).
[12] O. V. Pylypovskyi, D. Makarov, V. P. Kravchuk, Y. Gaididei, A. Saxena and D. D. Sheka, “Chiral Skyrmion and Skyrmionium States Engineered by the Gradient of Curvature”, Phys. Rev. Appl. 10, 064057 (2018).
[13] D. D. Sheka, O. V. Pylypovskyi, P. Landeros, Y. Gaididei, A. Kákay and D. Makarov, “Nonlocal chiral symmetry breaking in curvilinear magnetic shells”, Commun. Phys. 3, 128 (2020).
[14] C. Donnelly, A. Hierro-Rodrı́guez, C. Abert, K. Witte, L. Skoric, D. Sanz-Hernández, S. Finizio, F. Meng, S. McVitie, J. Raabe, D. Suess, R. Cowburn and A. Fernández-Pacheco, “Complex free-space magnetic field textures induced by three-dimensional magnetic nanostructures”, Nat. Nanotech. 17, 136–142 (2022).
[15] M. Yan, A. Kákay, S. Gliga and R. Hertel, “Beating the Walker limit with massless domain walls in cylindrical nanowires”, Phys. Rev. Lett. 104, 057201 (2010).
[16] J. A. Otálora, M. Yan, H. Schultheiss, R. Hertel and A. Kákay, “Curvature-induced asymmetric spin-wave dispersion”, Phys. Rev. Lett. 117, 227203 (2016).

A new method to measure and quantify the 3D mineralogical composition of particulate
materials using X-ray computed micro-tomography (CT) is presented. The new method is
part of a workflow designed to standardize the analysis of particles based on their
microstructures without the need to segment the individual classes or grains. Classification
follows a decision tree with criteria derived from particle histogram parameters that are
specific to each microstructure, which in turn can be identified by 2D-based automated
quantitative mineralogy. The quantification of mineral abundances is implemented at the
particle level according to the complexity of the particle by taking into consideration the
partial volume effect at interphases. The new method was tested on two samples with
different particle size distributions from a carbonate rock containing various microstructures
and phases. The method allowed differentiation and quantification of more mineral classes
than traditional 3D image segmentation that uses only the grey-scale for mineral classification.
Nevertheless, due to lower spatial resolution and lack of chemical information, not all
phases identified in 2D could be distinguished. However, quantification of the mineral
classes that could be distinguished was more representative than their 2D quantification,
especially for coarser particle sizes and for minor phases. Therefore, the new 3D method
shows great potential as a complement to 2D-based methods and as an alternative to traditional
phase segmentation analysis of 3D images. Particle-based quantification of mineralogical
and 3D geometrical properties of particles opens new applications in the raw
materials and particle processing industries.

River basins across the world are shaped by local land topography and generally have a dendritic structure formed by convergence of river streams originating in a watershed until they end up in the main river. These river basins are also home to a plethora of aquatic lifeforms. Movement patterns of riverine biodiversity, especially fishes, are shaped by dendritic structure of river networks (see Figure 1) and habitat capacity of river basins. The ongoing river networks project at CASUS is specifically aimed at developing models to study the effects of dendritic network topology on fish biodiversity and thereby be able to predict biodiversity patterns across various river basins. Starting with an initial distribution of fish species on the river network, we explore how the biodiversity patterns, such as local species richness (LSR), in dendritic river networks evolve with time, under the assumption of species being equivalent on a per capita basis. Such neutral biodiversity models have been able to successfully explain a suite of biodiversity indices of plant and animal species across various ecological systems. In summary, the river project aims to bring together the neutral biodiversity theory and the framework of dispersal over networks to make predictions on biodiversity in riverine systems across the world. This would enable understanding the factors shaping present biodiversity and allow us to explore how climate change might affect future riverine biodiversity.

The centenary of the birth of H. Gobind Khorana provides an auspicious opportunity to review the origins and evolution of parallel advances in biophysical methodology and molecular genetics technology used to study membrane proteins. Interdisciplinary work in the Khorana laboratory in the late 1970s and for the next three decades led to productive collaborations and fostered three subsequent scientific generations whose biophysical work on membrane proteins has led to detailed elucidation of the molecular mechanisms of energy transduction by the light-driven proton pump bacteriorhodopsin (bR) and signal transduction by the G protein–coupled receptor (GPCR) rhodopsin. This review will highlight the origins and advances of biophysical studies of membrane proteins made possible by the application of molecular genetics approaches to engineer site-specific alterations of membrane protein structures.

Dynamics of two types of chiral magnetic domain walls in magnetic cylindrical nanowires under spin-polarised current are investigated by means of micromagnetic simulations. We show that Bloch point domain wall with chirality identical to that of the Oersted field can propagate without dynamical instabilities with velocities ca. 300 m/s. Domain wall width is shown to widen for a larger current density which limits the velocity increase. For domain walls with opposite chirality, we observed a new pinning mechanism created by the action of the Oersted field and limiting their propagation distance even after chirality switching. Vortex-antivortex domain walls transform into Bloch point domain wall, after which they can unexpectedly propagate either along or against the current direction. Our results demonstrate that domain wall dynamics under current in cylindrical magnetic nanowires can result in a plethora of different behaviors which will have important implications for future 3D spintronic devices.

U₃Cu₄Ge₄ is a uniaxial ferromagnet that displays a first-order magnetization process (FOMP) at 25 T for field applied along the hard b axis. Here, we report on ultrasound and magnetostriction measurements of U₃Cu₄Ge₄ in static and pulsed magnetic fields up to 40 T. The FOMP causes stepwise anomalies in the magnetoelastic properties. U₃Cu₄Ge₄ elongates along the a and c axes and shrinks along the b axis, leading to an almost zero volume effect. The sound velocities of the longitudinal and transverse acoustic waves decrease sharply at the FOMP, whereas the sound attenuation shows pronounced peaks. An analysis of the ultrasound data using a mean-field theory suggests the existence of quadrupolar interactions and crystal-electric-field effects. The 5 f electronic states are between itinerant and localized, typical of uranium-based intermetallic compounds.

This document is the first version of the Data Management Plan (DMP) of the project ”advanced Muon Campus in US and Europe contribution” (aMUSE), funded by the European Union under the call ”H2020-MSCA-RISE-2020” (Research and Innovation Staff Exchange) with Grant Agreement number 101006726.

The aMUSE project coordinates the activities of about 80 researchers from twelve European research institutes and industries participating to the search for New Physics in the muon sector and to the design of new generation muon accelerators in high-profile US laboratories (Fermilab, BNL, SLAC). The project involves the two Fermilab Muon Campus Experiments:

• Muon (g-2), aiming to shed light on the discrepancy on the anomalous magnetic momentum of the muon;

• Mu2e, whose goal is to improve by four order of magnitudes the discover sensitivity for the not yet observed conversion of a muon to an electron.

aMUSE proposes also an ambitious extension of the activities already foreseen for the Muon Campus: an RD program for innovative detectors for the Mu2e upgrade (Mu2e-II, with 10 times larger beam intensity) and the design of a new beamline for CLFV searches based on muon decays as an alternative to Mu2e-II. aMUSE also constitutes a launch pad for a European-USA network for the development of muon beams for low (CLFV) and high (muon collider) energy frontiers.

During the duration of the aMUSE project (from 1.1.2022 to 31.12.2025), this first version of the Data Management Plan will be regularly evaluated and eventually adjusted to suit the needs of the aMUSE project.

This document was submitted as deliverable D7.8 in Work Package 7.

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.

Radiation sources with a stable carrier-envelope phase (CEP) are highly demanded tools for field-resolved studies of light-matter interaction, providing access both to the amplitude and phase information of dynamical processes. At the same time, many coherent light sources, including those with outstanding power and spectral characteristics lack CEP stability, and so far could not be used for this type of research. In this work, we present a method enabling linear and non-linear phase-resolved terahertz (THz) -pump laser-probe experiments with CEP-unstable THz sources. THz CEP information for each pulse is extracted using a specially designed electro-optical detection scheme. The method correlates the extracted CEP value for each pulse with the THz-induced response in the parallel pump-probe experiment to obtain an absolute phase-resolved response after proper sorting and averaging. As a proof-of-concept, we demonstrate experimentally field-resolved THz time-domain spectroscopy with sub-cycle temporal resolution using the pulsed radiation of a CEP-unstable infrared free-electron laser (IR-FEL) operating at 13 MHz repetition rate. In spite of the long history of IR-FELs and their unique operational characteristics, no successful realization of CEP-stable operation has been demonstrated yet. Being CEP-unstable, IR-FEL radiation has so far only been used in non-coherent measurements without phase resolution. The technique demonstrated here is robust, operates easily at high-repetition rates and for short THz pulses, and enables common sequential field-resolved time-domain experiments. The implementation of such a technique at IR-FEL user end-stations will facilitate a new class of linear and non-linear experiments for studying coherent light-driven phenomena with increased signal-to-noise ratio.

Schon früh wurde am Helmholtz-Zentrum Dresden – Rossendorf (HZDR) die Relevanz eines nachhaltigen Umgangs mit Forschungsdaten und -Software gemäß FAIR-Prinzipen erkannt. Vor diesem Hintergrund wurden seit 2017 schrittweise neue (Forschungs-)Infrastrukturen wie das Invenio-basierte Forschungsdatenrepositorium RODARE geschaffen, Tools wie der Research Data Management Organizer (RDMO) adaptiert und am Zentrum implementiert sowie Data und Software-Policies vereinbart.

Seither stellen sich die Interessengruppen und Akteure den generellen Herausforderungen des Forschungsdatenmanagements (FDM) wie den multidisziplinären Anforderungen, den mehrstufigen Prozessen oder der nachgelagerten Betrachtung in Projektverläufen vor allem der spezifischen Situation am HZDR. Eigenständigkeit und Kooperation unter den einzelnen Instituten gehen am Zentrum Hand in Hand. Die daraus entstehende umfangreiche Bandbreite an wissenschaftlichen Themen hat zur Folge, das immer wieder sehr spezifische Anforderungen an das FDM herangetragen werden, welche großen Einfluss auf die konkrete Ausgestaltung der Lösungsansätze haben.

Das HZDR hat die überragende Bedeutung des Wissenstransfers im FDM erkannt und zur agilen Begegnung der genannten Herausforderungen konzeptionell wichtige Weichenstellungen vorgenommen. Das FDM-Team der Bibliothek und der Abteilung „Computational Science“ bündelt die Aktivitäten aller weiteren wichtigen Akteure (u. a. „Programmplanung und Internationale Projekte“, IT-Infrastruktur, Technologie-Transfer und Rechtsabteilung) rund um das Thema. Durch gemeinsame Entwicklungen entstehen Maßnahmen, welche den Anforderungen (Metadaten, Transfer, Dokumentation, Guidelines etc.) durch das aufeinander abgestimmte Zusammenspiel von technischen Werkzeugen (Weiterentwicklung RODARE, Integration FIS und RODARE, HZDR-Cloud, Projekt Dashboard HELIPORT, Automatisierte Software Publikation über HERMES, GitLab, Dokumentation im HZDR-internen MediaWiki etc.) und Serviceleistungen (Schulungen, Workshops, Beratungen) gerecht werden sollen.

Um die offerierten Tools und Services noch besser bekannt zu machen und an den einzelnen Punkten des Forschungs-/Publikationszyklus zu implementieren, werden das HZDR-Intranet als wichtige Plattform des Wissenstransfers für die einzelnen Wertschöpfungsprozesse entlang des Datenlebenszyklus neu konzipiert und übersichtliche sowie leicht handhabbare Möglichkeiten für den Direktkontakt zwischen Wissenschaft und Dienstleister geschaffen. Der dabei gewählte ganzheitliche Ansatz soll dabei helfen, alle Facetten von Open Science nachhaltig gestalten und zukünftigen Anforderungen aktiv begegnen zu können.

Das Poster will das Konzept vorstellen, zum konstruktiven Austausch einladen sowie als Inspirationsquelle für konsequente Weiterentwicklungen im FDM dienen.

Broken magnetic symmetry is a key aspect in condensed matter physics and in particular in magnetism. It results in the appearance of chiral effects, e.g. topological Hall effect [1] and non-collinear magnetic textures including chiral domain walls and skyrmions [2,3]. These magnetochiral effects originate from an antisymmetric exchange interaction, the intrinsic Dzaloshinskii-Moriya interaction (DMI). At present, tailoring of DMI is done rather conventionally by optimizing materials, either doping a bulk single crystal or adjusting interface properties of thin films and multilayers.
A viable alternative to the conventional material screening approach can be the exploration of the interplay between geometry and topology. In the emergent field of curvilinear magnetism chiral effects are associated to the geometrically broken inversion symmetries [4]. Those appear in curvilinear architectures of even conventional materials. There are numerous exciting theoretical predictions of exchange- and magnetostatically-driven curvature effects, which do not rely on any specific modification of the intrinsic magnetic properties, but allow to create non-collinear magnetic textures in a controlled manner by tailoring local curvatures and shapes [5,6]. Until now the predicted chiral effects due to curvatures remained a neat theoretical abstraction.
Here, I present the very first experimental confirmation of the existence of the curvature-induced chiral interaction with exchange origin in a conventional soft ferromagnetic material [7,8]. It is experimentally explored the theoretical predictions, that the magnetisation reversal of flat parabolic stripes shows a two step process. By measuring the domain wall depinning field, we established that it is linked to the exchange-induced DMI and scales with curvature, that is in line with the theoretical prediction. Furthermore, the exchange-induced DMI strength can be tuned by changing the local curvature at the apex of parabola.

[1] N. Nagaosa, et al., Nature Nanotech. 8, 899 (2013).
[2] U. K. Rößler, et al., Nature 442, 797 (2006).
[3] A. Fert, et al., Nature Rev. Mat. 2, 17031 (2017).
[4] Y. Gaididei, et al., Phys. Rev. Lett. 112, 257203 (2014).
[5] J. A. Otálora, et al., Phys. Rev. Lett. 117, 227203 (2016).
[6] V. P. Kravchuk, et al., Phys. Rev. Lett. 120, 067201 (2018).
[7] O. M. Volkov et al., Phys. Rev. Lett. 123, 077201 (2019).
[8] O. M. Volkov et al., Physica Status Solidi – Rapid Research Lett. 13, 1800309 (2019).

Bubble column reactors are extensively used in a variety of industrial processes involving gas-liquid mass transfer along with chemical reactions. Despite intensive research, knowledge on the mass transfer is still limited in comparison with that on the fluid dynamics, which provides an open field of research.

In this study, mass transfer of CO2 between air bubbles and water in a bubble column is investigated using Euler-Euler simulations in OpenFOAM. Previously validated fluid dynamics models are applied and focus is put on the description of the mass transfer. Experimental data to validate the results are taken from the study of Deckwer providing axial profiles of gas fraction, and carbon dioxide concentration in both phases. Previous work considering only cases with co-current absorption is extended to also include the cases with counter-current flow and desorption. Some simplifications are made in accordance with the previous work, i.e. taking the bubble diameter to be constant and using the experimentally determined values for the mass transfer coefficient. Despite these simplifications, the simulation results show a quite good agreement with the experimental data.

As a second step, the change in bubble size due to the mass transfer is included in the simulations by means of a population balance equation discretized using the class method. The well-known model of Brauer is implemented as an example of a bubble size dependent mass transfer coefficient. Since experimental data including the development of bubble size are not available for comparison, an initial validation is provided by comparison of the polydisperse calculation with two monodisperse calculations corresponding to initial and final size in the former.

Bubble columns and bubble column reactors are well established in the field of chemical and biochemical engineering. As the flow in such apparatus influence the performance of mixing or heat and mass transfer processes, numerous studies focus on the hydrodynamic description of the flow as well as the spatial distribution of bubbles inside the vessel. For the latter, the shear-induced lift force plays a key role as it acts lateral to the bubble rise direction and correspondingly affects the lateral distribution of bubbles. However, studies regarding the lift force usually focus on rather clean or uncontaminated systems, although even small amounts of surfactants are known to significantly change bubble characteristics like drag, coalescence and breakup behavior as well as the bubble shape in the case of ellipsoidal bubbles.
In previous studies we investigated the influence of surfactants on the lift force of ellipsoidal single bubbles and could reveal strong changes of the lift coefficient 𝐶 𝐿 in comparison to clean bubbles 1 . To elaborate the effect of the lift force in buoyancy driven bubbly flows, we present measurements conducted in a 2.0 m tall column with a polydisperse bubble size. This allows to study the development of bubble size-dependent gas fraction profiles along a distance that is sufficient for the effect of the lift force to unfold sufficiently. In these experiments, we added different dozes of 1-Pentanol to the flow in order to investigate a surfactant-related modification of the lift force in dependence on the contamination degree. We use shadowgraphic high-speed imaging to determine liquid velocity and gas phase properties. For the former we use a PIV-like technique called Particle Shadow Velocimetry, while for the latter we use a novel deep learning based procedure that uses Convolutional Neural Networks to
determine bubbles and reconstruct occluded bubble parts in the images. Although the addition of surfactants affects bubbles in multiple aspects, we link some of the findings to our previous studies on the shear-induced lift force and demonstrate the influence of surfactants on several flow characteristics in bubble columns.

This thesis focuses on the image processing methods for brain perfusion measurement using a magnetic resonance imaging (MRI) sequence called arterial spin labeling (ASL). We show the importance of dealing with brain volume changes as a measurement confounder, we propose a framework for integrating all processing steps in a robust processing pipeline, and lastly, we show an application of the ASL acquisition and processing to adverse effect measurements in healthy brain tissue of patients undergoing brain radio-chemotherapy demonstrating the usefulness of the method in uncovering structural and physiological changes in the brain.

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.

Iron and iron oxide nanostructures are of broad interest for numerous applications, such as in the fields of magnetic data
storage, spintronics, biosensing and catalysis. In all of these cases, defined deposition on nanometer scale is essential for
functionality. For conventional electrodeposition of transition metals, precise thickness control and layer stability at the
nanoscale are difficult due to dissolution tendencies in acidic electrolytes after the voltage is switched off. In contrast to
previous studies that focused on self-termination of Ni and Ni-based alloys, we investigate the thickness control of nanoscale
iron oxide/iron layers using self-terminated electrodeposition from sulfate electrolytes. Electrochemical quartz crystal
microbalance measurements show that self-terminated thickness can be controlled by both deposition potential and iron ion
concentration. Comparison of experimental results with model calculations based on diffusion theory reveal two different
growth modes for self-termination. At low iron ion concentration, self-termination of iron proceeds via the formation of an
ultrathin iron hydroxide layer. At larger iron ion concentration, precipitation of bulk Fe(OH)2 dominates the film growth and
self-termination is shifted to more negative potentials. All self-terminated layers exhibit enhanced stability in the electrolyte
after the voltage is switched off compared to those deposited in the conventional deposition regime. With in situ Rutherford
backscattering spectrometry measurements, we can follow the self-terminating deposition and the stability after voltage
switch-off for longer times online. Surface analytical and morphological analyses show that the self-terminated layers exhibit
a higher iron oxide/iron ratio and are smoother than layers obtained by conventional electrodeposition.

This repository contains scripts to reproduce the results of the publication
"Electronic Structure Machine Learning Surrogates without Training". Training data has to be downloaded separately.

We compare the ion-induced electron emission from freestanding monolayers of graphene and MoS2 to find a sixfold higher number of emitted electrons for graphene even though both materials have similar work functions. An effective single-band Hubbard model explains this finding by a charge-up in MoS2 that prevents low energy electrons from escaping the surface within a period of a few femtoseconds after ion impact. We support these results by measuring the electron energy distribution for correlated pairs of electrons and transmitted ions. The majority of emitted primary electrons have an energy below 10 eVand are therefore subject to the dynamic charge-up effects at surfaces.

A myriad of phenomena in materials science and chemistry rely on quantum-level simulations of the electronic structure in matter. While moving to larger length and time scales has been a pressing issue for decades, such large-scale electronic structure calculations are still challenging despite modern software approaches and advances in high-performance computing.
The silver lining in this regard is the use of machine learning to accelerate electronic structure calculations -- this line of research has recently gained growing attention.
The grand challenge therein is finding a suitable machine-learning model during a process called hyperparameter optimization. This, however, causes a massive computational overhead in addition to that of data generation.
We accelerate the construction of neural network models by roughly two orders of magnitude by circumventing excessive training during the hyperparameter optimization phase. We demonstrate our workflow for Kohn-Sham density functional theory, the most popular computational method in materials science and chemistry.

Multiregime closure models for the two-fluid model often focus on continuous-dispersed and large-scale interface flow morphologies (Cerne, Petelin and Tiselj, 2021), (Hänsch et al., 2012), (Mathur et al., 2019).
Thin liquid films at solid walls, e.g. in annular flow or film condensation, so far have not been considered in a multi-regime two-fluid (MTF) model.
Rather, thin liquid films are currently treated as large-scale interfaces.
The film interface thus has to be resolved, which is conflicting with the two-fluid model approach and increases computational cost.
For the interface resolving volume-of-fluid method, coupling to a liquid film (LF) model was previously proposed to treat subgrid size liquid films (Kakimpa, Morvan and Hibberd, 2016).
Here, we adapt this approach to the framework of the MTF model.
A film thickness transport equation and film momentum equation are solved in a shell region of the two-fluid model volume domain.
Mass- and momentum transfer between both models is included depending on a critical film volume fraction in the first cell at the wall.
Thus a hybrid representation of liquid films depending on the local film thickness is obtained in the proposed LF-MTF model.
The implementation in the CFD solver STAR-CCM+ is outlined and a basic verification case is presented.
Validation results of LF-MTF model simulations against X-ray microtomographic data of horizontal annular flow (Porombka et al., 2021) show qualitative agreement and outline paths for further model improvement.
Finally, simulation results of droplet separators demonstrate the applicability of the LF-MTF model to industrial CFD.

This document summarizes the aMUSE activities carried on in the first six months of the
project (January-June 2022). For each Work Package, an overview of the progresses done
so far is reported. Outreach, dissemination and training activities are also listed.

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 electrical conductivity results from simulating microscopic Ohm’s law using the real-time formalism of time-dependent density functional theory for conditions ranging from high-pressure solid at ambient temperature to earth-core conditions.

Die Präsentation im Rahmen eines Projekttreffens von "Circular by Design" stellt die wesentlichen Ergebnisse des Gutachtens vor.. Neben den gesetzlichen Grundlagen wird der aktuelle Stand in der Sammlung und Verwertung ebenso vorgestellt, wie gute Beispiele, die als Grundlage für die erarbeiteten Lösungsansätze und Handlungsempfehlungen dienen. ,

In water electrolyzer cells, active materials contain various fine-grained critical raw materials such as platinum group metals or rare earth elements. Although the readiness level of water electrolysis technology is high and large scale of hydrogen production is targeted worldwide, there has been no significant research on recycling of end of life (EOL) water electrolyzer cells. For a functioning circular economy, recycling processes for these valuable materials have to be developed especially on the fine particle scale below 100 μm.
The in-depth characterization of water electrolyzer cells and their components allows to assess their liberation behavior and subsequent separability based on different particle properties, e.g. size, density, wettability, etc. Thus, this paper aims at identifying the material composition and properties of proton exchange membrane electrolyzer cell (PEMEL) and high temperature electrolyzer cell (HTEL) before processing. In PEMEL, critical raw materials such as iridium, ruthenium, and platinum are used, while nickel, lanthanum, and yttrium are used in HTEL. Techniques such as automated mineralogical analysis (MLA), X-ray fluorescence spectroscopy and microscopy (XRF) and laser diffraction are used to identify the possibility of liberation. To ensure a high recovery rate of critical raw materials, the surface properties of individual component have been studied. Additional contact angle studies by means of pressed bubble and the particle attachment on single air bubbles revealed the wettability of membrane electrode assemblies and significant differences between the components. Furthermore, pH and salinity show to influence the wetting behaviour of the components. These findings provide the design of the separation study for EOL electrolyzer cells.

The exfoliation energy — quantifying the energy required to extract a two-dimensional (2D) sheet from the surface of a bulk
material — is a key parameter determining the synthesizability of 2D compounds. Here, using ab initio calculations, we present
a new group of non-van der Waals 2D materials derived from non-layered crystals which exhibit ultra low exfoliation energies.
In particular for sulfides, surface relaxations are essential to correctly describe the associated energy gain needed to obtain
reliable results. Taking into account long-range dispersive interactions has only a minor effect on the energetics and ultimately
proves that the exfoliation energies are close to the ones of traditional van der Waals bound 2D compounds. The candidates
with the lowest energies, 2D SbTlO3 and MnNaCl3, exhibit appealing electronic, potential topological, and magnetic
features as evident from the calculated band structures making these systems an attractive platform for fundamental and applied
nanoscience.

It is well known that structural defects have a remarkable influence on the optical, electrical, and catalytic properties of 2D materials. In addition to imaging utilization, irradiation with electron and ion beams allows precise control of defect generation by altering beam conditions and exposure dose4. We have studied the effects of ion irradiation on 2D materials by using first-principles calculations combined with analytical potential molecular dynamics. In particular, the defect production mechanisms for various free-standing and supported 2D targets were studied. The amount of damage in single-layer transition-metal dichalcogenides was explored under the impacts of noble gases with a wide range of energies and incident angles. We showed that ion irradiation can produce uniform pores in 2D transition metal dichalcogenides for applications such as gas separation. The possibility of changing defect concentrations opens a path for tuning electronic, and magnetic properties of 2D materials via a combination of thermal treatment and a reactive vapor. Moreover, defect engineering can be used to generate luminescent centers to enable quantum emitter applications.

Single-photon sources are one of the elementary building blocks for photonic quantum information and optical quantum computing [1]. One of the upcoming challenges is the monolithic photonic integration and coupling of single-photon emission, reconfigurable photonic elements and single-photon detection on a silicon chip in a controllable manner. Particularly, fully integrated single-photon emitters on-demand are required for enabling a smart integration of advanced functionalities in on-chip quantum photonic circuits [2].

This work presents a mask-free nanofabrication method involving a quasi-deterministic creation of scalable extrinsic color centers in silicon emitting in the optical telecom O-band [3] on a commercial silicon-on-insulator platform using focused ion beam writing. We also show the local writing of an intrinsic color center in silicon, which is linked to a tri-interstitial complex and reveals quantum emission close to the telecom band [4]. The successful integration of these telecom quantum emitters into photonic structures such as micro-resonators, nanopillars [5] and photonic crystals with sub-micrometer precision paves the way toward a monolithic, all-silicon-based semiconductor-superconductor quantum circuit.

[1]D. D. Awschalom et al.,Nature Photonics 12,516 (2018)
[2]J. C. Adcock et al.,IEEE, 27, 2, (2021)
[3]M. Hollenbach et al.,Optics Express 28,26111 (2020)
[4]Y. Baron et al.,arXiv:2108.04283 (2021)
[5]M. Hollenbach et al.,arXiv:2112.02680 (2021)

Radionuclide speciation inside long-term radioactive waste repositories needs to be
understood in order to ensure effective containment of the waste. Organic ligands
originating from the degradation of organic components inside such a repository can
possibly affect the mobility of radionuclides in solution. The present study focuses on
nitrilotriacetic acid, NTA, as a model molecule and europium, Eu(III), as a
nonradioactive analog with outstanding luminescence and magnetic properties.
The complexation of NTA with Eu(III) as a function of pH was studied using nuclear
magnetic resonance (NMR) spectroscopy. Samples were prepared with Eu(III) to NTA
ratios of 1:1 and 1:2 in D₂O with 1 M NaCl as background electrolyte to simulate high
ionic strength. The ¹H and ¹³C NMR spectra of the NTA solutions with Eu(III) show
clearly distinguishable signals for the free NTA and two Eu-NTA complexes, which is
indicative of a 1:1 and a 1:2 Eu-NTA complex. The interaction of Eu(III) with NTA is
relatively strong and favors the 1:2 Eu-NTA complex even in solution containing 1:1
Eu-NTA ratio, except in very acidic solutions. Time-resolved laser-induced
fluorescence spectroscopy (TRLFS) measurements yield quantitative information on
the complexation behavior.
As repository relevant cationic groundwater components, the influence of Ca(II) and
Al(III) on Eu(III) complexation with NTA is studied in detail with NMR spectroscopy.
This combination of NMR spectroscopy and TRLFS yields qualitative and quantitative
information on the coordination environment from the ligand’s and the metal ion’s
perspective, respectively. In subsequent studies focusing on ternary systems
comprising repository relevant solid phases (e.g. calcium aluminum silicate hydrate
(C-A-S-H) phases), radionuclides and organic ligands, this will allow the identification
of radionuclide speciation in solution and on solid phases.

Böhlen et al. [1] recently proposed a model that describes the magnitude of the normal tissue sparing Flash effect as a function of dose based on available in vivo data. The newly introduced flash modifying factor FMF translates doses applied at ultra-high dose rate to equivalent doses at conventional dose rate similar to the concept of relative biological effectiveness [1]. Primarily founded on rodent data, the model [1] includes only one study that demonstrated a dose-dependent Flash effect by length differences measured at 5 days-old zebrafish embryo (ZFE) after irradiation with electron doses of 5 – 12 Gy [2]. We studied this systematic overview about the available Flash data with great interest and acknowledged it as a very useful guidance for future Flash research. Coincidentally, we have just recently measured ZFE data in the high dose range (15 – 50 Gy) that appear to match very well with the existing rodent data.
Comparable to our previous studies at the ELBE accelerator [3, 4], one day-old ZFE were irradiated using electron beams of reference (mean dose rate 0.11 Gy/s) and ultra-high dose rate (UHDR; mean dose rate 0.9×105 Gy/s) (Fig. 1a). Normal tissue toxicity was quantified by analyzing the length deficit of the 5 days-old embryos compared to unirradiated controls. Since the controls grew on average 30% from irradiation to analysis this is the maximum length deficit that can be caused by irradiation. The derived FMF values extend the available ZFE data [2] and cover in a single experiment almost the entire dose range applied in the rodent studies for different tissues. Comparable to the rodent data (Fig. 1b) the ZFE FMF increases with dose.
The good agreement of our ZFE data with the rodent data [1] demonstrates the feasibility of the ZFE model for basic Flash effect studies, e.g., on the influence of physical beam parameters [3–6]. Hence, the ZFE model could be deployed as a high-throughput alternative to rodent studies at this translational level [5] promising the exploration of a large dose and dose rate range of clinically relevant beams.

We demonstrate a broadband photoconductive THz emitter compatible with femtosecond fiber lasers operating at wavelengths of 1.1 and 1.55 m. The emitted 1.5-cycle transient covers the spectral range up to 70 THz.

We utilize optical pump – THz probe spectroscopy to estimate electron mobility in strained GaAs/(In,Al)As core/shell nanowires. Our results demonstrate that strain-induced reduction of the effective electron mass leads to a remarkable increase of the mobility. The data analysis indicates an important role of the inhomogeneous plasmon broadening that may affect THz spectra of dense ensembles of nanowires.

At the High-Field High-Repetition-Rate Terahertz facility @ ELBE (TELBE)[1],
ultrafast terahertz-induced dynamics can be probed in various states of matter with highest precision. The TELBE sources offer both, stable and tunable narrowband THz radiation with pulse energies of several microjoules at high repetition rates and a synchronized coherent diffraction radiator,that provides broadband single-cycle pulses. The measurements at TELBE are data intensive, which can be as high as 20GB per experiment, that can lasts up to several minutes. As a result, the current data aquisition and data analysis stages are decoupled, where in the first step the primary data is processed and stored at HZDR and in a later step, restricted data access is made available to the user for post-processing.

In this poster contribution, we present an integrated workflow for post-processing of the experimental data at TELBE with in-built exchange of metadata between the experiment control software LabView and the workflow execution engine UNICORE[2]. We also present the guidance system HELIPORT[3] which manages the metadata of the associated project proposal and job information from UNICORE, and integrates with the electronic lab notebook (MediaWiki[4]), providing a user-friendly interface for monitoring the actively running experiments at TELBE.

[1] https://doi.org/10.1063/1.4978042
[2] https://doi.org/10.1109/HPCSim.2016.7568392
[3] https://doi.org/10.1145/3456287.3465477
[4] https://www.mediawiki.org/wiki/Project:About

1D spin-wave conduits are envisioned as nanoscale components of magnonics-based logic and computing schemes for future generation electronics. A-la-carte methods of versatile control of the local magnetization dynamics in such nanochannels are highly desired for efficient steering of the spin waves in magnonic devices. Here, we present a study of localized dynamical modes in 1-$\mu$m-wide Permalloy conduits probed by microresonator ferromagnetic resonance technique. We clearly observe the lowest-energy edge mode in the microstrip after its edges were finely trimmed by means of focused Ne+ ion irradiation. Furthermore, after milling the microstrip along its long axis by focused ion beams, creating consecutively ~50 and ~100 nm gaps, additional resonances emerge and are attributed to modes localized at the inner edges of the separated strips. To visualize the mode distribution, spatially resolved Brillouin light scattering microscopy was used showing an excellent agreement with the ferromagnetic resonance data and confirming the mode localization at the outer/inner edges of the strips depending on the magnitude of the applied magnetic field. Micromagnetic simulations confirm that the lowest-energy modes are localized within $\sim$15-nm-wide regions at the edges of the strips and their frequencies can be tuned in a wide range (up to 5 GHz) by changing the magnetostatic coupling (i.e. spatial separation) between the microstrips.

Optical pump – THz probe spectroscopy has been established as a tool for contactless probing of electronic transport in semiconductor nanowires (NWs) [1]. Particularly in III-V NWs, scattering rates of charge carriers, as well as their plasmonic resonances for typical doping levels, are located in the THz range. The analysis of the optical conductivity spectra using the localized surface plasmon model provides an estimation of the carrier density and the mobility.
Here, we employ THz spectroscopy to study electron mobility in the strained GaAs core of GaAs/InAlAs core/shell nanowires. Owing to the lattice mismatch between the core and the shell in these NWs, the bandgap energy in the strained GaAs core exhibits a reduction by up to 40% [2]. Our results demonstrate that this effect is accompanied by a notable increase in the electron mobility by 30-50% with respect to a bulk GaAs [3]. We discuss the role of various scattering mechanisms and their dependence on strain and temperature. In addition to the homogeneous plasmon broadening caused by the carrier scattering, we also observe an inhomogeneous broadening in dense ensembles of NWs as illustrated in Fig. 1(a). Our modelling demonstrates that such broadening stems from the plasmonic interaction between neighboring NWs leading to the shift of the plasmon frequency as shown in Fig. 1(b). This effect has to be considered in the analysis of THz response of NWs since it may result in a significant underestimation of the mobility values.

Core-shell nanowires (NWs) made of III-V semiconductors are promising nanostructures for optoelectronic and photovoltaic applications. One of the advantages is the possibility to epitaxially grow the NWs on Si substrates despite the large lattice mismatch, since the Si-GaAs interface area is very small. Moreover, the large surface-to-volume ratio for the NWs’ core allows to impose a very large strain when the core is overgrown with a lattice-mismatched shell, without creating any misfit dislocations. In this way, the bandgap of the core semiconductor can be tuned in a broad range via strain engineering [1].
Pump-probe terahertz spectroscopy has been proven as a perfect tool for contactless probing of electrical properties of semiconductor NWs [2]. The analysis of the optical conductivity spectra using the localized surface plasmon model allows to estimate the carrier lifetime and the carrier mobility. Recently, using THz spectroscopy we have demonstrated that the mobility in highly strained GaAs NW cores can exceed the mobility in bulk GaAs by 30-50% [3]. We found out the particular importance of the geometrical factor that defines the rescaling of the localized surface plasmon frequency in NWs. Its dependence on the aspect ratio can be derived analytically in the approximation of the cylindrical NW shape [4]. However, for a dense ensemble of NWs, where some can form bundles or touch each other, the geometric factor may vary, leading to an inhomogeneous broadening of the plasmon resonances. We discuss the role of this effect and its impact on the estimation of carrier mobility.
Finally, we demonstrate a THz nonlinearity of photodoped GaAs/In0.2Ga0.8As core-shell NWs using single-cycle intense THz pulses with peak electric fields up to 0.6 MV/cm. We found that with increasing the peak THz field, the plasmon frequency demonstrates a redshift accompanied by a suppression of the spectral weight. Remarkably, the spectral weight does not remain proportional to the square of the plasmon frequency, indicating an onset of a spatially inhomogeneous carrier distribution across the NW. The observed behavior can be ascribed to nonlinear effects caused by the intervalley scattering occurring in the high electric field regime. However, in contrast to bulk semiconductors, this effect initially sets in at hot spots of the NW where the local electric field is enhanced by the plasmonic resonance [5].

[1] L. Balaghi et al., Nat. Commun. 10, 2793 (2019).
[2] H. J. Joyce et al., Semicond. Sci. Technol. 31, 103003 (2016)
[3] L. Balaghi et al., Nat. Commun. 12, 6642 (2021).
[4] I. Fotev et al., Nanotechnology 30, 244004 (2019).
[5] R. Rana et al., Nano Lett. 20, 3225 (2020).

Using gold-implantated germanium, where the carrier lifetime is shortened by more than three orders of magnitude, we have demonstrated a broadband photoconductive THz emitter compatible with modelocked fiber lasers operating at wavelengths of 1.1 and 1.55 um and pulse repetition rates up to 20 MHz. The emitted THz spectrum spans up to 70 THz. This approach opens up a prospect for manufacturing of compact, high-bandwidth THz photonic devices compatible with Si CMOS technology.

Radiation-induced property changes in materials originate with the energy transfer from an incoming particle to a lattice and the displacement of the atoms from their original location. The displaced atoms can, depending on conditions, lead to the formation of extended defects such as dislocation loops, voids, or precipitates. The non-equilibrium defects created during damage events and that determine the extent of these larger defects are a function of dose rate, material, and temperature. However, these defects are transient and can only be probed indirectly. This work presents direct experimental measurements and evidence of non-equilibrium vacancy formation during irradiation, where in-situ positron annihilation spectroscopy was used to prove the generation of non-equilibrium defects in silicon.

We measured the electronic energy-loss straggling of protons, helium, boron and silicon ions in silicon using a time-of-flight approach. Ions with velocities 0.25 - 1.6 times the Bohr velocity were transmitted through single-crystalline Si(100) nanomembranes in either channelling or random geometry to study the trajectory dependence of energy-loss straggling. Nuclear and path length contributions were determined with the help of Monte Carlo simulations. Our results exhibit an increase in straggling with increasing ion velocity for channelled trajectories for all projectiles as well as for protons and helium in random geometry. For heavier ions, electronic straggling at low velocities does not decrease further but plateaus and even seems to increase again. A satisfying agreement between experiment and transport cross section calculations for helium shows that energy deposition of light ions is dominated by electron-hole pair excitations. No agreement is found for boron and silicon indicating that local electron-promotion and charge-exchange events significantly contribute to energy loss at low velocities.

Pheochromocytomas (PCCs) are rare but potentially lethal tumors that arise from the adrenal medulla. The clinical suspicion and diagnosis of PCC can be challenging due to the non-specific nature of signs and symptoms. In many patients, infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could lead to long-term symptoms including fatigue, headaches, and cognitive dysfunction. Here, we present the case of a patient incidentally diagnosed with an adrenal mass that proved to be a PCC after imaging was performed due to persisting complaints after coronavirus disease 2019 (COVID-19) infection. A 37-year-old male patient was referred to our center because of a right-sided inhomogeneous adrenal mass, incidentally found during a computed tomographic scan of the thorax performed due to cough and dyspnea that persisted after COVID-19 infection. Other complaints that were present prior to COVID-19 infection included profuse sweating, dizziness, exhaustion with chronic fatigue, and concentration difficulties. The patient had no history of hypertension, his blood pressure was normal, and the 24-h ambulatory blood pressure monitoring confirmed normotension but with the absence of nocturnal dipping. Plasma normetanephrine was 5.7-fold above the upper limit (UL) of reference intervals (738 pg/ml, UL = 129 pg/ml), whereas plasma metanephrine and methoxytyramine were normal at 30 pg/ml (UL = 84 pg/ml) and <4 pg/ml (UL = 16 pg/ml), respectively. Preoperative preparation with phenoxybenzamine was initiated, and a 4-cm tumor was surgically resected. Profuse sweating as well as dizziness was resolved after adrenalectomy pointing toward PCC and not COVID-19-associated patient concerns. Altogether, this case illustrates the difficulties in recognizing the possibility of PCC due to the non-specific nature of signs and symptoms of the tumor, which in this case did not include hypertension and coincided with some of the symptoms of long COVID-19.

We have studied the microscopic magnetic properties, the nature of the 130 K phase transition, and the ground state in the recently synthesized compound CeRh₂Ga by use of ^69,71Ga nuclear quadrupole resonance (NQR). The NQR spectra clearly show an unusual phase transition at T_t ∼ 130 K, yielding a splitting of the hightemperature single NQR line into two well-resolved NQR lines, providing evidence for two crystallographically inequivalent Ga sites. The NQR frequencies are in good agreement with fully relativistic calculations of the band structure. Our NQR results indicate the absence of magnetic or charge order down to 0.3 K. The temperature dependence of the spin-lattice relaxation rate 1/T₁ shows three distinct regimes, with onset temperatures at T_t and 2 K. The temperature-independent 1/T₁, observed between Tt and 2 K, crosses over to a Korringa process, 1/T₁ ∝ T , below ∼2 K, which evidences a rare two-ion Kondo scenario: The system evolves into a dense Kondo coherent state below 2.0 and 0.8 K probed by the two different Ga sites.

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.