Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

We developed a theoretical model that estimates the bubble size from sub-millimeter orifices under variable gas flow conditions. The model is successfully tested for orifices with diameters in the range of 0.2 mm to 1 mm under both quasi-static and dynamic bubbling regimes. The model is able to predict the final bubble radius with an accuracy better than 20% compared with the experimental results. Moreover, we explicitly look into the influence of the gas reservoir volume V_c upstream of the orifice on the gas reservoir pressure P_c by simultaneously monitoring the events, i.e. changes in the state of bubble, upstream and downstream of orifices. We found that, variations in P_c reduce as V_c increases. Analysis of the dynamics of the dominating forces acting on a bubble show that, enlarging V_c mainly amplifies the gas momentum force and the liquid inertia force. Hence, the bubble detachment mechanism may no longer be only buoyancy driven.

In entwickelten Ländern ist die Abwasseraufbereitung für etwa 1 % des gesamten elektrischen Energieverbrauchs verantwortlich, wobei die biologische Behandlung in Belebungsbecken bis zu 80 % des gesamten Energieverbrauchs ausmacht. Zudem wird für die nahe Zukunft ein Anstieg des Energieverbrauchs im Wassersektor um 80 % prognostiziert. Ein wesentlicher Faktor dabei ist die Verwendung energieintensiver Druckbelüftungssysteme, um den für die biologische Aktivität notwendigen Sauerstoff bereitzustellen. Wissenschaftler des Helmholtz-Innovationslabors CLEWATER arbeiten daran, die Effizienz des Belüftungsprozesses deutlich zu steigern. In diesem Artikel werden die aktuellen Fortschritte bei zwei von CLEWATEC vorgeschlagenen Ansätzen zur effizienten Belüftung vorgestellt.

In recent decades, a wealth of new electrochemical energy storage systems have emerged as well as a variety of novel and advanced materials for conventional systems. Once new systems and materials are introduced, they are often challenged by performance degradation such as capacity loss and the increase in cell resistance. Since degradation processes could also raise safety issues such as gas evolution and short-circuiting events, understanding charge storage and degradation mechanisms plays a crucial role in further development. In this work, some of the progress on unvailing charge storage and degradation mechanisms for various electrochemical energy storage systems will be presented. In particular, relying on ex-situ and in-situ technologies, X-ray diffraction, scanning transmission electron microscopy, neutron radiography, degradation processes of advanced electrode materials such as layered nickel-rich cathodes [1-3] and MXene [4] in lithium-ion batteries will be discussed. Additionally, some of the critical limitations of in-situ technologies, such as the radiolysis process in transmission electron microscopy, will be introduced, including the simulation work based on the reaction-diffusion model. [5, 6] Finally, we introduce our recent work on understanding the charge storage mechanism of membrane-free alkali metal-iodide (A-AI) batteries relying on ex-situ neutron radiography.
Acknowledgement:
This project has received funding from the European Union’s Horizon 2020 research and innovation
programme under grant agreement No 963599.

References:

1. C. Xu, K. Marker, J. Lee, A. Mahadevegowda, P. J. Reeves, S. J. Day, M. F. Groh, S. P. Emge, C. Ducati, B. Layla Mehdi, C. C. Tang and C. P. Grey, Nat. Mater., 2021, 20, 84-92.
2. W. Li, I. Siachos, J. Lee, S. A. Corr, C. P. Grey, N. D. Browning and B. Layla Mehdi, Microsc. Microanal., 2021, 27, 1254-1255.
3. J. Lee, H. Amari, M. Bahri, Z. Shen, C. Xu, Z. Ruff, C. P. Grey, O. Ersen, A. Aguadero, N. D. Browning and B. L. Mehdi, Batteries & Supercaps, 2021, DOI: 10.1002/batt.202100110.
4. J. Lee, D. Spurling, O. Ronan, W. Li, I. Siachos, V. Nicolosi and B. Layla Mehdi, Microsc. Microanal., 2021, 27, 1976-1977.
5. J. Lee, D. Nicholls, N. D. Browning and B. L. Mehdi, Phys. Chem. Chem. Phys., 2021, 23, 17766-17773.
6. D. Nicholls, J. Lee, H. Amari, A. J. Stevens, B. L. Mehdi and N. D. Browning, Nanoscale, 2020, 12, 21248-21254.

The effect of static mechanical strain on the splitting of spin sublevels of color centers based on spin 3/2 silicon vacancies in silicon carbide at room temperature has been shown. The deformed heterointerface of the AlN/4H-SiC structure has been studied. Stresses near the heterointerface have been determined using con- focal Raman spectroscopy. The spin–strain coupling constants −0.1 GHz/strain and −0.8 GHz/strain for the V2 center in 4H-SiC have been experimentally determined for the first time using the optically detected magnetic resonance method. The results obtained can be used to control spin states in SiC by means of the controlled piezoelectric strain in AlN and to estimate the fine-structure parameter D of spin centers using Raman scattering. Such an estimate makes it possible to forecast magnetometric parameters of nanosensors based on SiC nanocrystals.

The alpaka library is a header-only C++14 abstraction library for accelerator development. Its aim is to provide performance portability across accelerators through the abstraction (not hiding!) of the underlying levels of parallelism.

Repulsive and long-range exciton-exciton interactions are crucial for the exploration of one-dimensional (1D) correlated quantum phases in the solid state. However, the experimental realization of nanoscale confinement of 1D dipolar exciton has thus far been limited. Here, we demonstrated atomically precise lateral heterojunctions based on transitional-metal dichalcogenides (TMDC) as a new platform for 1D dipolar excitons. The dynamics and transport of the interfacial charge transfer excitons in a type II WSe2-WSSe lateral heterostructure were spatially and temporally imaged using ultrafast microscopy. The expansion of the exciton cloud driven by dipolar repulsion was found to be strongly density dependent and highly anisotropic. The interaction strength between the 1D excitons was determined to be ~3.9 × 10^-14 eV cm^-2 corresponding to a dipolar length of 310 nm, which is a factor of 2-3 larger than the interlayer excitons at two-dimensional van der Waals vertical interfaces. These results suggest 1D dipolar excitons with large static in-plane dipole moment in lateral TMDC heterojunctions as a new system for investigating quantum many-body physics.

Continuous casting is the primary means of production of steel semi-products. It is of paramount importance to keep the quality of the produced stock constantly at a high level to meet the tight margins of the steel industry. Flow conditions in the mould, where the solidification process starts, significantly impact the quality of the end product. Unfortunately, the harsh industrial environment limits the applicable measurement methods to detect any undesired flow conditions, thus limiting the viable control strategies.Contactless Inductive Flow Tomography (CIFT) was previously proposed to identify flow features in the mould of a continuous caster. While the Electromagnetic Brake (EMBr) is a common way to influence the flow, it has a disturbing influence on CIFT measurements which, however, can be compensated. In this work, we introduce the experimental setup, measurement technique, and discuss the control strategy derived from the CIFT flow reconstruction.

The damage-induced voltage alteration (DIVA) contrast mechanism in scanning electron microscope (SEM) has been studied in broad range of the primary electron beam energies, with a special emphasis on the ultra-low energy range. The SEM imaging contrast related to resistivity changes in the In(0.55)Al(0.45)P irradiated with He2+ ions of 600 keV was subjected to an analysis in a range of 10 keV down to 10 eV of primary electron energies. The problem of specimen charging in ultra-low energy range and its effect on the contrast in SEM images has been tackled for the first time. Contrary to expectations based on the classical total emission yield approach, the potentials formed at the highly resistive part of irradiated area led to dramatic increase in the intensity of registered signal for primary electron energies below E1, which can be explained as signal saturation due to potential on the specimen surface acting as repeller for primary electrons. Nevertheless, the experimental data presenting the influence of the beam energy on the potential formation on the surface of an insulating material under electron irradiation have been presented for the first time in ultra-low energy regime.

We present the effect of substitution-induced pressure on the reversibility of the magnetocaloric effect (MCE) in Ni₂Cr_xMn_1.4−xIn_0.6 (x = 0.1, 0.2, 0.3) alloys, through characterization in pulsed magnetic fields.We measured the adiabatic temperature change ΔT_ad directly during applied magnetic field pulses of 2 and 6 T. We paid special attention to the reversibility of ΔT_ad. The substitution of Mn by Cr in Ni₂Mn_1.4In_0.6 leads to a negative pressure, as evidence by the increase of the lattice parameters, which shifts the martensitic transition towards lower temperatures and enhances the ferromagnetism of the martensite phase.We found a large value of ΔT_ad = −7 K at T = 270 K for the sample with x = 0.1 for a field change of 6 T. We discuss the reversibility of the MCE in these alloys in terms of the Clausius-Clapeyron equation.

Single crystals of the hexagonal triangular lattice compound AgCrSe₂ have been grown by chemical vapor transport. The crystals have been carefully characterized and studied by magnetic susceptibility, magnetization, specific heat, and thermal expansion. In addition, we used Cr-electron spin resonance and neutron diffraction to probe the Cr 3d³ magnetism microscopically. To obtain the electronic density of states, we employed x-ray absorption and resonant photoemission spectroscopy in combination with density functional theory calculations. Our studies evidence an anisotropic magnetic order below T_N = 32 K. Susceptibility data in small fields of about 1 T reveal an antiferromagnetic (AFM) type of order for H ⊥ c, whereas for H II c the data are reminiscent of a field-induced ferromagnetic (FM) structure. At low temperatures and for H ⊥ c, the field-dependent magnetization and AC susceptibility data evidence a metamagnetic transition at H⁺ = 5 T, which is absent for H II c. We assign this to a transition from a planar cycloidal spin structure at low fields to a planar fanlike arrangement above H⁺. A fully ferromagnetically polarized state is obtained above the saturation field of H_⊥S = 23.7 T at 2K with a magnetization of M_s = 2.8 μ_B/Cr. For H II c, M(H) monotonically increases and saturates at the same M_s value at H_IIS = 25.1 T at 4.2 K. Above T_N , the magnetic susceptibility and specific heat indicate signatures of two dimensional (2D) frustration related to the presence of planar ferromagnetic and antiferromagnetic exchange interactions. We found a pronounced nearly isotropic maximum in both properties at about T^∗ = 45 K, which is a clear fingerprint of short range correlations and emergent spin fluctuations. Calculations based on a planar 2D Heisenberg model support our experimental findings and suggest a predominant FM exchange among nearest and AFM exchange among third-nearest neighbors. Only a minor contribution might be assigned to the antisymmetric Dzyaloshinskii-Moriya interaction possibly related to the noncentrosymmetric polar space group R3m. Due to these competing interactions, the magnetism in AgCrSe₂, in contrast to the oxygen-based delafossites, can be tuned by relatively small, experimentally accessible magnetic fields, allowing us to establish the complete anisotropic magnetic H-T phase diagram in detail.

Complexation by small organic ligands controls the bioavailability of contaminants and influences their mobility in the geosphere. We have studied the interactions of Cm3+, as a representative of the trivalent actinides, and Eu3+, as an inactive homologue, with glucuronic acid (GlcA) a simple sugar acid. Time-resolved laser-induced luminescence spectroscopy (TRLFS) shows that complexation at pH 5.0 occurs only at high ligand to
metal ratios in the form of 1:1 complexes with standard formation constants log β0 = 1.84 ± 0.22 for Eu3+ and log β0 = 2.39 ± 0.19 for Cm3+. A combination of NMR, QMMM, and TRLFS reveals the structure of the complex to be a half-sandwich structure wherein the ligand binds through its carboxylic group, the ring oxygen, and a hydroxyl group in addition to five to six water molecules. Surprisingly, Y3+, which was used as a diamagnetic reference in NMR, prefers a different coordination geometry with bonding through at least two hydroxyl groups on the opposite side of a distorted GlcA molecule. QMMM simulations indicate that the differences in stability among Cm, Eu, and Y are related to ring strain induced by smaller cations. At higher pH a stronger complex was detected, most likely due to deprotonation of a coordinating OH group.

Hardening of Fe-9%Cr alloys exposed to irradiation with Fe²⁺ ions of two different energies, 1 and 5 MeV, is investigated using nanoindentation. The limited penetration depth of the ions causes steep damage gradients in the near-surface volumes of the irradiated samples. This damage gives rise to graded microstructures resulting in depth-dependent irradiation hardening. Nanoindentation integrates the depth-dependent hardness over the indentation plastic zone. Our study combines quantitative analysis of the ion-irradiated microstructures with the determination of the full depth dependence of irradiation hardening. The microstructure-informed model incorporates direct experimental evidence revealed by a former investigation using cross-sectional scanning transmission electron microscopy. For both ion energies, the observed microstructures consist of dislocation loops with band-like distributions and are concluded to be the dominant source of the measured irradiation-induced hardening. The model predictions are found to be in reasonable agreement with the as-measured nanoindentation response. The comparison of hardening predictions with different kinds of superposition rules of hardening contributions suggests linear superposition as the most appropriate selection under the present conditions. The possible transferability of these results to neutron irradiation is also discussed.

To achieve an optimal flow pattern in the mould of a continuous caster, it is desirable to use a tailored control of the flow using electromagnetic actuators (e.g. electromagnetic brakes or stirrers) based on the current flow condition in the mould. However, the rough environment provides a challenge. Contactless Inductive Flow Tomography (CIFT) is a technique that can provide information about the flow structure by visualizing the full velocity field in the mould. In order to reconstruct the flow, the perturbation of an applied magnetic field by the flow is measured. It is obvious that every change of the strength of the magnetic field of an electromagnetic brake influences the measured values. In this paper we cover the challenges of measuring the flow induced magnetic field in the range of nT in the presence of varying magnetic field of the electromagnetic actuators in the range of 100 mT.

The quality of steel produced by a continuous caster depends on the flow condition during initial solidification in the mould. While the understanding of the flow and its effects is highly desirable, high temperature, opaqueness of the liquid steel and harsh conditions during the production limit viable measurement methods. Contactless Inductive Flow Tomography (CIFT) can provide information about the dominant flow structure in the mould in real time. This information can be used in a control loop for the Electromagnetic Brake (EMBr). Due to the inductive nature of CIFT, every change of the magnetic field strength of the EMBr has a strong influence on the measurements. Changing the strength of the EMBr alters the magnetization vector in its ferromagnetic yoke, which, in turn, generates a signal up to a thousand times higher than the flow induced magnetic field.
In this paper, we present a way to compensate these effects of EMBr on CIFT by filling a database containing compensation values. We will also present the preliminary results of a controller that utilizes CIFT and EMBr to actively control the flow in the mould during casting. The experiments are conducted on the Mini-LIMMCAST facility, a laboratory model of the mould of a continuous caster with the rectangular cross-section of 300 × 30 mm2. It is operated with the eutectic ally GaInSn.

The alpaka library is a header-only C++14 abstraction library for accelerator development. Its aim is to provide performance portability across accelerators through the abstraction (not hiding!) of the underlying levels of parallelism.

The alpaka library is a header-only C++14 abstraction library for accelerator development. Its aim is to provide performance portability across accelerators through the abstraction of the underlying levels of parallelism.

In der Nuklearmedizin werden Radionuklide für die Diagnose oder die Therapie von Tumoren verwendet. Das Quecksilberisotop ₁₉₇Hg und das dazugehörige metastabile _197mHg wecken großes Interesse in diesem Gebiet. Ziel dieser Arbeit ist es daher, Moleküle, basierend auf einem Bispidingrundgerüst zu synthetisieren, die eine kovalente Bindung von Hg₂₊ über Phenylgruppen ermöglichen, um so eine Freisetzung und damit verbundene unspezifische Anreicherung des Quecksilbers in vivo zu verhindern. Der Schwerpunkt liegt dabei auf der Funktionalisierung eines spezifischen Bispidolderivates, um dieses an ein biologisches Molekül knüpfen zu können. Letztendlich soll eine Synthesestrategie erarbeitet werden, die eine Herstellung dieser Bispidole ermöglicht.

This talk is fossued on current strategies and future perspectives using the alpha-emitters actinium-225 and radium-223/-224 for targeted alpha therapy.

Current reactive transport model (RTM) uses transport control as the sole arbiter of differences in reactivity. For the simulation of crystal dissolution, a constant reaction rate is assumed for the entire crystal surface as a function of chemical parameters. However, multiple dissolution experiments conirmed the existence of an intrinsic variability of reaction rates, spanning two to three orders of magnitude. Modeling this variance in the dissolution process is vital for predicting the dissolution of minerals in multiple systems. Novel approaches to solve this problem are currently under discussion. Critical applications
include reactions in reservoir rocks, corrosion of materials, or contaminated soils. The goal of this study is to provide an algorithm for multi-rate dissolution of single crystals, to discuss its software implementation, and to present case studies illustrating the diference between the single rate and multi-rate dissolution models. This improved model approach is applied to a set of test cases in order to illustrate the diference between the new model
and the standard approach. First, a Kossel crystal is utilized to illustrate the existence of critical rate modes of crystal faces, edges, and corners. A second system exempliies the efect of multiple rate modes in a reservoir rock system during calcite cement dissolution in a sandstone. The results suggest that reported variations in average dissolution rates can be explained by the multi-rate model, depending on the geometric conigurations of the crystal surfaces.

In an ongoing effort towards a more sustainable rare-earth element market, there is a high potential for an efficient recycling of rare-earth elements from end-of-life compact fluorescent lamps by physical separation of the individual phosphors. In this study, we investigate the separation of five fluorescent lamp particles by high-gradient magnetic separation in a rotary permanent magnet separator. We thoroughly characterize the phosphors by ICP-MS, laser diffraction analysis, gas displacement pycnometry, surface area analysis, SQUID-VSM, and Time-Resolved Laser-Induced Fluorescence Spectroscopy. We present a fast and reliable quantification method for mixtures of the investigated phosphors, based on a combination of Time-Resolved Laser-Induced Fluorescence Spectroscopy and parallel factor analysis. With this method, we were able to monitor each phosphors’ removal dynamics in the high-gradient magnetic separator and we estimate that the particles’ removal efficiencies are proportional to (d².χ)^(1/3). Finally, we have found that the removed phosphors can readily be recovered easily from the separation cell by backwashing with an intermittent air–water flow. This work should contribute to a better understanding of the phosphors’ separability by high-gradient magnetic separation and can simultaneously be considered to be an important preparation for an upscalable separation process with (bio)functionalized superparamagnetic carriers.

The anisotropy in semiconductor nanoplatelets (NPLs) is reflected in the anisotropy of their crystal structure and organic ligand shell, which can be used for creating new semiconductor heterostructures. This work demonstrates the synthesis of core/shell NPLs containing zero-dimensional (0D) Cd_xHg_1−xSe domains embedded in CdSe NPLs via cation exchange. The strategy is based on the different accessibility of definite regions of the NPLs for incoming cations upon time-limited reaction conditions. The obtained heterostructures were successfully overcoated with a Cd_yZn_1−yS shell preserving their two-dimensional (2D) morphology. The NPLs exhibit bright photoluminescence in the range of 700-1100 nm with quantum yields up to 55%, thus making them a prospective material for light-emitting applications in the near-infrared spectral range.

Quartz and feldspar in end-of-life biological shielding concrete in nuclear power plants exhibit a maximum volume expansion at a neutron fluence of 10⁹ n/cm² of 17.8 % and 7.7 % respectively. [1] To simulate neutron-radiation damage, shallow ion-penetration depths in the order of a few hundred nanometers are optimal for 2D examinations of radiation-induced structural changes in silicate minerals and subsequent hydraulic weathering under aqueous alkaline conditions.

Using vertical scanning interferometry (VSI) we observed an out-of-plane expansion for quartz within concrete equivalent to 18.8 vol. % using Si-ion radiation with a fluence of 5·10¹⁴ ions/cm² and an energy of 300 keV. This agrees well with results recently acquired by Luu et al. (2021), [2] who achieved 18.1 vol. % using a Si-ion fluence and beam energy each an order of magnitude higher (6·10¹⁵ ions/cm², 3000 keV). These irradiation conditions correspond to penetration depths calculated in SRIM [3] of respectively 430 nm and 2000 nm.

By virtue of the resistance to polishing exhibited by feldspars, it is difficult to reduce the inherent surface roughness down to submicron relief required for VSI and even finer for electron backscatter diffraction (EBSD). Furthermore, structural relaxation in feldspar begins further away from the surface than quartz. We polish mineral specimen surfaces using a low-energy and -incident Ar+ broad ion beam (Ar-BIB) prior to Si-ion irradiation. In addition to depth profile changes due to radiation-induced structural relaxation and subsequent aqueous alkaline dissolution using VSI, we examine structural changes using EBSD in conjunction with electron scanning microscopy (SEM).

[1] Le Pape et al. (2018) J. Adv. Conc. Technol. 16 191-209
[2] Luu et al. (2021) J. Nucl. Mat. 545 152734
[3] Ziegler et al. (2010) Nucl. Instrum. Methods Phys. Res. B268 1818-1823 (http://www.SRIM.org)

We report on a series of fully resolved simulations of the flow around a rigid sphere translating steadily near a wall, either in a fluid at rest or in the presence of a uniform shear. Non-rotating and freely rotating spheres subject to a torque-free condition are both considered to evaluate the importance of spin-induced effects. The separation distance between the sphere and wall is varied from values at which the wall influence is weak down to gaps of half the sphere radius. The Reynolds number based on the sphere diameter and relative velocity with respect to the ambient fluid spans the range 0.1 - 250, and the relative shear rate defined as the ratio of the shear-induced velocity variation across the sphere to the relative velocity is varied from -0.5 to +0.5, so that the sphere either leads the fluid or lags behind it. The wall-induced interaction mechanisms at play in the various flow regimes are analyzed qualitatively by examining the flow structure, especially the spanwise and streamwise vorticity distributions. Variations of the drag and lift forces at low-but-finite and moderate Reynolds number are compared with available analytical and semiempirical expressions, respectively. In more inertial regimes, empirical expressions for the two force components are derived based on the numerical data, yielding accurate fits valid over a wide range of Reynolds number and wall-sphere separations for both non-rotating and torque-free spheres.

Die numerische Simulation hat sich in den letzten Jahrzehnten stetig weiterentwickelt und ist im Bereich der Aerodynamik und der Hydrodynamik zu einem etablierten Werkzeug für die Auslegung und Fehleranalyse von Bauteilen herangereift. Der Schwerpunkt der Forschung verlagert sich daher zunehmend auf die numerische Simulation mehrphasiger Strömungen. Derartige Mehrphasenströmungen zeichnen sich durch eine hohe Dynamik, komplexe physikalische Vorgänge und eine große Spanne an Längenskalen aus, die überwiegend mit den sich ausbildenden Grenzflächen zusammenhängen. Insbesondere in der Chemie- und Verfahrenstechnik sind solche Problemstellungen häufig anzutreffen und entsprechend viel Forschungsbedarf ist vorhanden. Allerdings liegt der Schwerpunkt der jeweiligen Forschungsarbeit und Modellentwicklung jeweils auf numerischen Simulationen für eine spezifische Morphologie: a) Verfahren zur Simulation von dispersen Strukturen, bei welchen die Grenzflächen durch das numerische Gitter nicht erfasst werden (Euler-Euler, Euler-Lagrange) und b) Verfahren, bei welchen die Grenzflächen aufgelöst werden (Volume-of-Fluid, Level-Set). Jedoch gibt es eine Vielzahl von technischen Fragestellungen, bei denen die auftretenden Morphologien – und damit das am besten geeignete Verfahren – nicht a priori bekannt sind. Hierzu gehören u. a. Flotationszellen, Kältemaschinen, biologische und chemische Reaktoren, Destillationskolonnen, Drall-basierte Abscheider oder Fliehkraftpumpen für mehrphasige Strömungen. Seit einiger Zeit werden für derartige Problemstellungen spezielle hybride Simulationsmethoden entwickelt: 2-Feld-Ansätze mit entsprechendem Morphologieblending, 4-Feld-Ansätze mit spezifischen numerisch motivierten Phasen, Drift-Flux-Methoden auf Volume-of-Fluid-Basis oder auch das Blending zwischen Simulationsmethoden wie Euler-Euler und Level-set.
Der vorliegende Beitrag stellt einen 4-Feld-Ansatz vor, welcher seit einiger Zeit am Helmholtz-Zentrum Dresden-Rossendorf in der quelloffenen Bibliothek OpenFOAM entwickelt und validiert wird. Die wesentlichen Entwicklungskriterien und -ziele sind:

• robuste Anwendbarkeit für ingenieurstechnische Fragestellungen in der Chemie- und Verfahrenstechnik,
• Anwendung eines einheitlichen Satzes von Gleichungen, welcher die verschiedenen Simulationsmethoden enthält (kein Blending zwischen den Methoden),
• für hochauflösende numerische Gitter sollen die Ergebnisse für aufgelöste Grenzflächen denen einer algebraischen Volume-of-Fluid-Simulation entsprechen,
• für niedrigauflösende Gitter sollen die Ergebnisse für disperse Strukturen denen des Euler-Euler-Verfahrens entsprechen,
• Phasen, welche eine aufgelöste Grenzfläche ausbilden, und Phasen, welche dispers in einer anderen Phase vorliegen, sind eigenständige numerische Phasen,
• ein Morphologieübergang zwischen aufgelösten und dispersen Strukturen soll über entsprechende Massentransfermodelle zwischen den numerischen Phasen realisiert werden und
• disperse Phasen sollen mit aufgelösten Grenzflächen interagieren können (Übergang, Aufplatzen, Schaumbildung).

The measurements of neutron capture cross sections of neutron-rich nuclei are challenging but essential for understanding nucleosynthesis and stellar evolution processes in the explosive burning scenario. In the quest of r-process abundances, according to the neutrino-driven-wind model, light neutron-rich unstable nuclei may play a significant role as seed nuclei that influence the abundance pattern. Hence, experimental data for neutron capture cross sections of neutron-rich nuclei are needed. Coulomb dissociation of radioactive ion beams at intermediate energy is a powerful indirect method for inferring capture cross section. As a test case for validation of the indirect method, the neutron capture cross section (n, γ ) for 14C was inferred from the Coulomb
dissociation of 15C at intermediate energy (600A MeV). A comparison between different theoretical approaches and experimental results for the reaction is discussed. We report for the first time experimental reaction cross sections of 28Na(n, γ ) 29Na, 29Na(n, γ ) 30Na, 32Mg(n, γ ) 33Mg, and 34Al(n, γ ) 35Al. The reaction cross sections were inferred indirectly through Coulomb dissociation of 29,30Na, 33Mg, and 35Al at incident projectile energies around 400–430 A MeV using the FRS-LAND setup at GSI, Darmstadt. The neutron capture cross sections were obtained from the photoabsorption cross sections with the aid of the detailed balance theorem. The reaction rates for the neutron-rich Na, Mg, Al nuclei at typical r-process temperatures were obtained from the measured (n, γ ) capture cross sections. The measured neutron capture reaction rates of the neutron-rich nuclei, 28Na, 29Na, and 34Al are significantly lower than those predicted by the Hauser-Feshbach decay model. A similar trend was observed earlier for 17C and 19N but in the case of 14C(n, γ ) 15C the trend is opposite. The situation is more complicated when the ground state has a multi-particle-hole configuration. For 32Mg, the measured cross section is about 40–90% higher than the Hauser-Feshbach prediction.

Magnetic dipole strength functions have been deduced from averages of large numbers of M1 transition strengths calculated within the shell model for the nuclides 105Cd, 106Cd 111Cd, and 112Cd. Enhancements of the M1 strengths toward low transition energy have been found for all nuclides considered. These properties are compared with those of experimental photon strength functions obtained from (3He,3He') experiments, which seem to indicate
a disappearance of the low-energy enhancement in the heavier isotopes.

The inherent three-dimensional topology of vNWs imposes several constraints to their fabrication and their integration in other circuits. We present here the use of Hydrogen silsesquioxane (HSQ) for the fabrication of single electron transistors (SETs) based on vNWs.

This work reports the CMOS compatible and monolithic fabrication of a conventional planar field effect transistor (FET) co-integrated with a quantum dot (QD) based single electron transistor (SET). The FET process fabrication is adapted to fulfill the restrictions imposed by the pre-fabricated SET, such as reduced thermal budget, extra protection layers and modified doping in order to obtain low threshold voltage. The resulting FET presents good subthreshold characteristics and the SET preserves its integrity at the end of the fabrication.

The extraction of metals such as copper or indium is essential for the economy, but inevitably associated with the generation of vast amounts of tailings. Especially flotation tailings lead to huge land consumption and are a potential source of environmental hazards. However, due to limited processing technologies in the past such mining waste typically contains remarkable concentrations of valuable elements. Therefore, it is sensible to combine modern resource with environmental technologies to supplement the recovery of valuables with the removal of hazardous substances such as arsenic or cadmium. In the ideal scenario the residues can be utilized for underground backfilling or dump construction.
The project partners GEOS, SAXONIA and HIF have started to develop, build and optimize a pilot plant for the processing of material from primary and secondary sources using bioleaching, metal extraction and elimination of hazardous components based on various research projects. The pilot plant, consisting of different modules, combines biotechnology with physical separation and processing technologies in an innovative and sophisticated way to recover valuables and remove pollutants. The bioleaching module leaches tailings in an airlift reactor by means of selected microorganisms under specific process conditions (pH, temperature, etc.). The obtained yields of up to 90% indium and 85-90% copper indicate the promising potential of this bioleaching technique. For the metal recovery module, it is planned to integrate the following main processing stages: solvent extraction, absorber columns (e.g. activated carbon, IX resin) and electrolysis. The so-called environmental module is designed as classical precipitation, flocculation and sedimentation unit for treatment of remaining process streams from the metal recovery module to eliminate hazardous substances. A future aim is running the mobile pilot plant directly at the tailings site.
An overview on the development of the modules, the equipment and the results that were obtained so far will be presented.

Hydrogen has the largest gravimetric energy density among all chemical fuels. At the same time, the density of gaseous H₂ is extremely low, which makes its compression to high pressures, liquefaction, or solid-state storage necessary for transport purposes. Liquid hydrogen (LH₂) can be transported in a dewar under atmospheric pressure, but this requires energy-intensive cooling down to 20 K. Magnetocaloric materials have great potential to revolutionize gas liquefaction to make LH₂ more competitive as fuel. In this paper, we investigate a series of Laves-phase materials regarding their structural, magnetic, and magnetocaloric properties in high magnetic fields. The three compounds HoAl₂, Ho_0.5Dy_0.5Al₂, and DyAl₂ are suited for building a stack for cooling from liquid-nitrogen temperature (77 K) down to the boiling point of hydrogen at 20 K. This is evident from our direct measurements of the adiabatic temperature change in pulsed magnetic fields, which we compare with calorimetric data measured in a static field. With this methodology, we are now able to study the suitability of magnetocaloric materials down to low temperatures up to the highest magnetic fields of 50 T.

Quantum spin liquids are exotic states of matter that form when strongly frustrated magnetic interactions induce a highly entangled quantum paramagnet far below the energy scale of the magnetic interactions. Three-dimensional cases are especially challenging due to the significant reduction of the influence of quantum fluctuations. Here, we report the magnetic characterization of K₂Ni₂(SO4)₃ forming a three-dimensional network of Ni²⁺ spins. Using density functional theory calculations, we show that this network consists of two interconnected spin-1 trillium lattices. In the absence of a magnetic field, magnetization, specific heat, neutron scattering, and muon spin relaxation experiments demonstrate a highly correlated and dynamic state, coexisting with a peculiar, very small static component exhibiting a strongly renormalized moment. A magnetic field B ≳ 4 T diminishes the ordered component and drives the system into a pure quantum spin liquid state. This shows that a system of interconnected S = 1 trillium lattices exhibits a significantly elevated level of geometrical frustration.

Metallic antiferromagnets with broken inversion symmetry on the two sublattices, strong spin-orbit coupling, and high Neel temperatures offer alternative opportunities for applications in spintronics. Especially Mn₂Au, with a high Neel temperature and high conductivity, is particularly interesting for real-world applications. Here, manipulation of the orientation of the staggered magnetization, (i.e., the Neel vector) by current pulses was recently demonstrated, with the readout limited to studies of anisotropic magnetoresistance or x-ray magnetic linear dichroism. Here we report on the in-plane reflectivity anisotropy of Mn₂Au(001) films, which are Neel vector aligned in pulsed magnetic fields. In the near-infrared region, the anisotropy is approximately 0.6%, with higher reflectivity for the light polarized along the Neel vector. The observed magnetic linear dichroism is about 4 times larger than the anisotropic magnetoresistance. This suggests the dichroism in Mn₂Au is a result of the strong spin-orbit interactions giving rise to anisotropy of interband optical transitions, which is in line with recent studies of electronic band structure. The considerable magnetic linear dichroism in the near-infrared region could be used for ultrafast optical readout of the Neel vector in Mn₂Au.

We report the crystal structure and magnetic behavior of the 4d³ spin-3/2 silicophosphate MoP₃SiO₁₁ studied by high-resolution synchrotron x-ray diffraction, neutron diffraction, thermodynamic measurements, and ab initio band-structure calculations. Our data revise the crystallographic symmetry of this compound and establish its rhombohedral space group (R¯3c) along with the geometrically perfect honeycomb lattice of the Mo³⁺ ions residing in disconnected MoO₆ octahedra. Long-range antiferromagnetic order with the propagation vector k = 0 observed below T_N = 6.8 K is a combined effect of the nearest-neighbor in-plane exchange coupling J ≃ 2.6 K, easy-plane single-ion anisotropy D ≃ 2.2 K, and a weak interlayer coupling J_c ≃ 0.8 K. The 12% reduction in the ordered magnetic moment of the Mo³⁺ ions and the magnon gap of Δ ≃ 7 K induced by the single-ion anisotropy further illustrate the impact of spin-orbit coupling on the magnetism. Our analysis puts forward single-ion anisotropy as an important ingredient of 4d³ honeycomb antiferromagnets despite their nominally quenched orbital moment.

Stoff- und Energieumwandlungsprozesse in technischen Apparaten sind oft an Mehrphasenströmungen gekoppelt. Beispiele dafür sind Chemiereaktoren, Stoffaustauschapparate, Kraftwerksanlagen oder Abwasserbehandlungsanlagen. Für die Modellierung der Strömungsvorgänge wurden in der jüngeren Vergangenheit numerische Berechnungsverfahren der Computational Fluid Dynamics entwickelt. Für diese besteht immer wieder die Aufgabe, sie mit realen Messdaten aus Strömungsexperimenten unter prozessähnlichen Bedingungen zu validieren bzw. aus solchen Messdaten Modelle und Korrelationen abzuleiten.
Der Vortrag gibt einen Einblick in die Nutzung innovativer schneller Bildgebungsverfahren für Mehrphasenströmungen für diesen Zweck. Vorgestellt werden die Gittersensortechnik sowie die ultraschnelle Röntgentomographie, welche am Helmholtz-Zentrum Dresden-Rossendorf entwickelt wurden. Mit beiden Bildgebungsverfahren ist die tomographische Analyse von Mehrphasenströmungen mit Bildraten von mehr als 1000 Bildern pro Sekunde sowie einer räumlichen Auflösung im Millimeterbereich möglich. Ihre Anwendung wird anhand verschiedener Beispiele für die Optimierung energieintensiver Prozesse, wie etwa Destillation und Abwasserbehandlung, exemplarisch diskutiert.

Multiphase flows are to be found in many production processes in the process industry. Examples are bubble column reactors, distillation columns, fluidized beds and many more. Measuring process parameters in such systems is very difficult because most sensors are disturbed in their fundamental measuring principles by the presence of particles and interfaces. Especially in fundamental fluid mechanics science, there is a growing need for imaging techniques for studying multiphase flows. There, the derivation of so-called CFD-grade data from fluid dynamics experiments requires imaging techniques with high spatial resolution, non-intrusiveness and ability to deal with the opacity of multiphase mixtures, walls and inserts in process vessels and their mock-ups. The presentation will give an overview of the state of the art of selected tomographic imaging techniques and discuss their application in solving chemical engineering problems.

Deep Reinforcement Learning (DRL) provides a potential toolset that enables industrial robots to autonomously learn manipulation skills, but the learning efficiency (success rate within certain learning episodes) is the bottleneck. In this work, we ascertained well-designed environmental observations to be vital for improving efficiency. To determine the impacts of different observations, we conducted simulation experiments of robots grasping, and evaluated three popular categories of environment observations -positions of the Tool-Center-Point, raw images from a fixed viewpoint camera, and image features (Sobel, Laplacian, HOG, LBP). The results indicate “image features” proved to be superior to the others, they contribute to higher success rate and learning speed.

In this first UMB-II project-meeting, the results of the first 6 months are summerized and presented. HZDR fucusses on the set up of microcosm-experiments and presents the first data.

Technetium (Tc) is a radioactive element, 99-Tc being its most abundant isotope. 99-Tc is mainly generated by anthropogenic sources like nuclear power plants, nuclear weapon detonations (99-Tc is the fission product of 235-U and 239-Pu), and hospitals due to its use in radiodiagnostics (99-Tc is the daughter of 99m-Tc). The emission of 99-Tc is of environmental concern since it is a b- emitter with a long life time (0.213 million years) and a high mobility in groundwater under oxic conditions. Therefore, a deep understanding of the environmental behavior of Tc is crucial to ensure a safe Tc storage in a nuclear waste repository and the protection of the environment.

The environmental behavior of Tc, its bioavailability, and its mobility in groundwater are ruled by environmental conditions like redox conditions, pH, presence of ions or minerals, and temperature among others. The knowledge about basic Tc chemistry helps to identify and understand the environmental conditions under which Tc migration is limited. Additionally, it allows for the development of possible Tc scavengers for remediation of polluted sites.

At the Institute of Resource Ecology (IRE) we study Tc immobilization by various natural materials such as pyrite (FeS₂) and materials found in nuclear waste repositories, such as green rust (Fe(II)-Fe(III) hydroxide). To answer the question, how Tc interacts with these materials, we employ a multitude of experimental techniques including X-ray diffraction, X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), Raman microscopy, scanning electron microscopy (SEM), and geochemical modeling approaches. This allows us to obtain an in-depth understanding of Tc chemistry, which can be used to develop and improve Tc scavengers and to build a safe nuclear waste repository.

Techntium-99 (⁹⁹Tc) is one of the most concerning fission products due to its long half-life (2.14∙105 years) and the high mobility of the anion pertechnetate (TcO₄⁻).
Tc migration decreases when Tc(VII) is reduced to Tc(IV). This scavenging step is carried out by Fe(II) minerals, which have been widely studied due to their versatility, low cost and ubiquity. Green rust is a Fe(II)-Fe(III) hydroxide that possesses adsorption, anion exchange and reduction capabilities. Its presence is expected in the near- and far-field of a nuclear waste repository because it is an iron corrosion product, and it is also formed in the environment when Fe²⁺ interacts with Fe(III) minerals. Thus, further studies are needed to both identify the optimal Tc scavenging conditions by green rust and the mechanism responsible of Tc retention. Batch contact studies have been performed under a wide range of conditions, i.e. pH (3-11), Tc concentration (nM-mM), and ionic strength (0-0.1 M). X-ray powder diffraction, Raman microscopy, X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) provided information on Tc oxidation state and speciation as well as on secondary redox products related to the Tc interaction with chloride green rust (GR(Cl)). In addition, re-oxidation experiments have been performed for one year to analyze the Tc retention reversibility. The results show that GR(Cl) removes Tc from solution with efficiencies between 80% (Kd = 8.0∙10³ mL/g) and ≈100% (Kd = 9.9∙10⁵ mL/g) for pH > 6.0.
In contrast, Tc removal for pH < 6.0 drops with decreasing pH, and ranges from 80% to 50% (Kd = 2.0∙10³ mL/g), reaching a minimum at pH 3.5. XPS analysis reveals the predominance of Tc(IV) at all evaluated pH values (3.5 to 11.5), supporting that Tc reductive immobilization is the main retention mechanism. Re-oxidation experiments show that Tc is slowly solubilized when time increases.
The analysis of the extended X-ray absorption fine structure (EXAFS) reveals a change on Tc(IV) environment depending on pH and Tc loading. The most probable structural rearrangements are represented by Tc(IV) sorption on Fe(III) minerals formed as secondary phases with Tc polynuclear species contribution.

Microbial consortia are proven to be one of the most effective tools for the decolorization of textile industrial dyes and effluent. The microbial consortium offers several benefits in bioremediation, some of them include the faster rate of dye degradation and high efficiency, tolerance to drastic environmental changes, possession of concerted metabolic activities due to presence of multiple microbial species that carry out maximum catalysis of dye molecule or sometimes complete mineralization, and its feasibility in practical scale operations due to less requirements of sterile conditions and cost effectiveness. This chapter critically summarizes the basic principles of microbial interactions such as mutualism and commensalism as the most valuable microbial relationships within the consortium that are beneficial for the bioremediation of wastewater. Several different microbial consortia which combined the microbial species of bacteria, fungus, yeast, along with algae and plants which have been used for the treatment of textile dyes/effluent have been thoroughly evaluated. All combinations have their own advantages and disadvantages, which have been explored herein. Bacterial species are fast growing microorganisms while fungal species contain highly catalytic enzymatic system, thus their combinations have been quite successful. Microalgae and plants have recently attracted researcher because of their potential of bioremediation and subsequent utilization of their biomass in biofuel generation which is commercially beneficial along with environmentally sustainable approach. Moreover, this chapter provides a brief introduction on newly emerging high-throughput techniques that deal with the engineering of synthetic microbial consortium for bioremediation and environmental cleanup.

Objective: Industrial wastewaters are secondary sources of many critical and base metals. Recovering these metals from such waste streams helps in resource recycling and reduce the environmental burden. However, such a recovery is challenging due to the low concentration of target metals and the presence of other unwanted metals at higher concentrations. Ion flotation is a promising separation process for resource recycling of metals from secondary sources. However, secondary pollution by used chemicals and low selectivity amongst ionic species limit its practical application so far. Thus, there is a need to develop new ion collectors, which are highly selective, efficient, and ecofriendly. Microbial biomolecules, which can act as complexing agent and can bind selectively to specific metal ionic species are attractive alternative. Biosurfactants are microbial surface-active molecules having both hydrophilic and hydrophobic groups, and therefore have surface activity and metal complexing ability making them an interesting candidate for flotation reagent. Rhamnolipid, a glycolipid type of biosurfactant, is reported to complex with variety of metals. In order to improve the application of biosurfactant in these processes, a comprehensive and systematic investigation of their performance and behavior as an ion collector is required. Our objective is to provide an insight into the surface activity, foamability and foam characterization for rhamnolipid for their application in bioionflotation. In the current study, rhamnolipid was investigated for its application as an ion collector in BioIonFlotation for Ga recovery.
Results: Rhamnolipid exhibits extensive foaming over a wide range of pH. Foam produced by rhamnolipid alone has higher foam stability making it difficult to collect the
flotation concentrates. Addition of 1,2-decanediol introduces the little destability to this foam and also aids in concentrate collection.
Aggregation studies – Mixing of rhamnolipid and Ga solutions resulted in colloidal suspension. These colloidal interactions were studied in presence and absence of Ga and/or 1,2 decaneciol by dynamic light scattering. The aggregate size of rhamnolipid molecules was largely influenced by the presence of Ga and/or 1,2 decanediol. Increase in aggregate size, indicated that interaction of rhamnolipid with either or both of them boosted the aggregation process.
Dynamic surface activity – Presence and absence of Ga and/or 1,2 decaneciol had significant impact on dynamic surface activity of rhamnolipid. Presence of Ga shifted the surface activity curve of rhamnolipids. This change in trend can be attributed to the complexation of rhamnolipid with Ga that lead to longer diffusion at the sub-surface and then to interface resulting in higher surface ages. Addition of 1,2 decanediol had no such effect, whereas presence of both contributed in further shifting of the surface activity curve (Fig. 1).
Foam characterization – Foam produced by rhamnolipid was characterized by dynamic foam analyzer. Interaction of rhamnolpid with Ga and 1,2 decanediol or both, changed the foaming behavior of rhamnolipid. Images of foam revealed the differences in size and shape of bubbles as well as their development.
Conclusion: The study investigated the role of rhamnolipid biosurfactant as an ion collector for its application in flotation. The influence of Ga, as target metal and 1,2 decanediol as additional frother on properties of rhamnolipid were evaluated and found to have a significant impact. Such studies provide in-depth insights on the parameters influencing the properties of flotation collectors and provide the basis for the development of the bioionflotation process.

In the effort of achieving high-energetic ion beams from the interaction of ultrashort laser pulses with a plasma, volumetric acceleration mechanisms beyond Target Normal Sheath Acceleration have gained attention.
A relativisticly intense laser can turn a near critical density plasma slowly transparent, facilitating a synchronized acceleration of ions at the moving relativistic critical density front. While simulations promise extremely high ion energies in in this regime, the challenge resides in the realization of a synchronized movement of the ultra-relativistic laser pulse ($a_0\gtrsim 30$) driven reflective relativistic electron front and the fastest ions, which imposes a narrow parameter range on the laser and plasma parameters. We present an analytic model for the relevant processes, confirmed by a broad parameter simulation study in 1D- and 3D-geometry. By tayloring the pulse length and plasma density profile at the front side, we can optimize the proton acceleration performance and extend the regions in parameter space of efficient ion acceleration at the relativistic relativistic density surface.

Hydrocarbons are abundant in icy giant planets like Uranus and Neptune. Their interiors are governed by extreme conditions with pressures of hundreds of gigapascals and temperatures of thousands of kelvins. It is possible to generate such extreme conditions in materials on a nanosecond timescale via laser-driven shock compression in the laboratory. A simple representative of hydrocarbons for use in the laboratory is polystyrene (C₈H₈). The formation of nanodiamonds from laser-induced shock compression of polystyrene was demonstrated at the Linac Coherent Light Source (LCLS) via 𝘪𝘯 𝘴𝘪𝘵𝘶 X-ray diffraction (XRD). This technique is based on driving two time-delayed shock waves through the material, such that they overlap at the sample rear side. Subsequently, a rarefaction wave releases the material at hypervelocity. The goal of the current work is the physical capture, extraction and characterisation of those generated nanodiamonds to better understand their formation process. In a larger framework, the project pursues the long-standing goal in condensed matter physics to recover metastable structures that form under extreme pressure and temperature conditions. This work presents an analysis of 𝘪𝘯 𝘴𝘪𝘵𝘶 XRD data deducing estimates of nanodiamond nucleation rates relevant to planetary interiors observed in the above mentioned experiment at LCLS and compares them to the latest theoretical model. Furthermore, seven recovery experiments, among them four recovery-only campaigns, were designed, prepared and conducted with the support of our working group and an eighth one was designed and prepared. High speed recordings were obtained giving unprecedented insights into the dynamics of the hypervelocity ejecta cloud and its impact into the various catcher types made from different materials. First analysis campaigns including chemical procedures for sample preparation, Raman spectroscopy, X-ray diffraction, dynamic light scattering, scanning and transmission electron microscopy, and tomography were arranged and some performed. Various collaborations were initiated, that among others enabled the usage of state-of-the-art materials and diagnostics, access to other facilities and support through simulations. The thesis provides a solid foundation for further research taking on the challenging task of recovering the nanodiamonds formed via laser-induced shock compression of hydrocarbons. This research can have crucial implications for planetary interior models of the icy giant planets.

After a short overview about the activities of our research group the concept of selective transmitter coatings on top of black body absorbers for the use in high-temperature solar thermal applications will be introduced.[1,2] Solar selective transmitters, which are also called heat mirrors, are characterized by a high solar transmittance and a high thermal reflectance. They can consist either of dielectric/metal/dielectric multilayers or of transparent conductive oxides (TCOs),[3] but only the latter one’s are suitable for high-temperature applications. The design of a TCO on top of a black body has a series of advantages compared to multilayer- or cermet-based solar-selective coatings (SSCs). Bare absorbers can be transformed into selective ones, the functionality is almost independent on film thicknesses, the fabrication is relatively easy and the concept is adaptable to specific requirements with respect to the operation temperature of the solar-thermal application.
The conceptual introduction will be followed by a review of recent developments in the field, which include the excellent high-temperature in-air stability of such type of solar coating when based on Sn-doped In₂O₃ (ITO).[4] In the main part of the talk, the development, optical modelling, properties and thermal stability of another TCO, Ta-doped SnO₂, are reported.[5] Its cutoff, i.e. the wavelength where it changes from transmitting to reflecting, is tunable from 1.7 µm to 2.4 µm. The optical properties of SnO₂:Ta are almost independent on the film thickness. The TCO is stable up to 800 °C in high vacuum and in air for 12 hours (at least) as shown by ion beam analysis, X-ray diffraction, ellipsometry and reflectometry. When the SnO₂:Ta is deposited on silicon and glassy carbon transforms these bare absorbers into selective ones. Finally, as part of the whole SSC concept, the formation, structure, and optical properties of dense, PVD-grown CuCr₂O₄ thin films is reported. This potential high-temperature absorber is obtained in high purity from as-deposited samples by a simple in-air annealing step at 800 °C and absorbs light in the whole solar range from 300 nm to 2500 nm.[6]

[1] Kennedy, C. E. Review of Mid- to High-Temperature Solar Selective Absorber Materials. Report No. NREL/TP-520-31267, (NREL - National Renewable Energy Laboratory, Golden, Colorado, USA, 2002).
[2] Granqvist, C. G. Transparent conductors as solar energy materials: A panoramic review. Solar Energy Materials and Solar Cells 91, 1529-1598, doi:10.1016/j.solmat.2007.04.031 (2007).
[3] Fan, J. C. C. & Bachner, F. J. TRANSPARENT HEAT MIRRORS FOR SOLAR-ENERGY APPLICATIONS. Applied Optics 15, 1012-1017, doi:10.1364/ao.15.001012 (1976).
[4] Wang, H., Haechler, I., Kaur, S., Freedman, J. & Prasher, R. Spectrally selective solar absorber stable up to 900 degrees C for 120 h under ambient conditions. Solar Energy 174, 305-311, doi:10.1016/j.solener.2018.09.009 (2018).
[5] Lungwitz, F. et al. Transparent conductive tantalum doped tin oxide as selectively solar-transmitting coating for high temperature solar thermal applications. Solar Energy Materials and Solar Cells 196, 84-93, doi:10.1016/j.solmat.2019.03.012 (2019).
[6] Krause, M. et al. Formation, structure, and optical properties of copper chromite thin films for high-temperature solar absorbers. Mater. 18, doi:10.1016/j.mtla.2021.101156 (2021).

The presentation will give a brief overview of microbial leaching in general and uranium ore leaching in particular. The microbial metabolism and its influencing variables as well as the chemistry and the actual technical process will be discussed. Finally, the advantages and disadvantages of the biotechnological process are compared to a conventional process and the main challenges in this context are mentioned.

Single Electron Transistors (SETs) open the way to semiconductor devices with extremely low power consumption. Quantum mechanical effects are used in such transistors: field-controlled tunneling of single electrons from a source to a drain via a quantum dot. SETs can be manufactured as thin Si pillars (source and drain) with a Si oxide layer in-between containing one Si quantum dot (Fig. 1). After SiOx formation by ion beam mixing, a thermally activated phase separation including Ostwald ripening results in a self-organization of Si nanocrystals in the SiO2 layer acting as Si quantum dots (Si NDs). For SET operation at room temperature, the diameter of the Si pillars needs to be < 12 nm, the Si ND diameter must be in the range of 2…3 nm and the distances between Si NDs and source/drain cannot be larger than 1.5 nm allowing quantum mechanical tunneling of the electrons.
Thus, Transmission Electron Microscopy (TEM) must be used for the structural characterization of these SETs. Si NDs inside the SiO2 matrix can only be detected by using the Si plasmon loss in the energy-filtered TEM mode. TEM sample preparation is challenging because of the very small 3D structure of the pillars (Fig.2) and the need for very thin TEM lamellae (30…40 nm in thickness). The Focused Ion Beam (FIB) lift-out technique can be used to prepare such samples. Setting markers and gradual thinning of the lamella from both sides (with TEM inspection in between) is necessary.
Surprisingly, comprehensive TEM studies uncovered that the oxide layer of a Si/ SiO2/Si layer stack can become dramatically thinner in pillars fabricated from this stack by Reactive Ion Etching (RIE). The oxide layer thinning depends on the pillar diameter. For instance, an originally 8 nm thick SiO2 layer is reduced to 2.6 nm in 15 nm diameter pillars. In order to prove that this oxide shrinkage is caused by RIE and not by sample preparation the most critical process in the FIB preparation - which is the electron-beam-assisted carbon-protection-layer deposition - was analyzed in detail: pillars were irradiated with different electron doses and then, the SiO2 thickness was measured in the TEM. As can be seen in Fig. 3 there is a clear influence of the electron dose on the oxide thickness. This can be explained by charge accumulation in pillar Si caps (drain), followed by dielectric breakdowns through filament formation across the SiO2 layer accompanied by Si oxide dissociation and oxygen emanation from the SiO2 disc rim of the pillars. However, as can be seen in Fig. 3 the FIB-caused contribution to the oxide thickness reduction is only a small part. The main contribution comes from the pillar RIE process based on the same physical reason (charging of the pillar Si caps).
This work was supported by the European Union’s H-2020 research project ‘IONS4SET’ under Grant Agreement No. 688072

Künstliche Intelligenz als Überbegriff steht schon länger im Fokus von Klinikern, Gesundheitsökonomen und medizinischen Wissenschaftlern. Entdeckungen in diesem weiten Feld sind aber nur vereinzelt im klinischen Alltag sichtbar, da insbesondere die diagnostische Entscheidungshoheit dem Menschen zugestanden wird. Doch steht schon heute fest: Der Einsatz von künstlicher Intelligenz wird nach und nach zu einem Wandel in der Medizin führen.

Heavy hydrogen isotopes are an essential resource with multiple applications in energy production, medicine and science. Unfortunately, the relative scarcity of heavy hydrogen in comparison to the much more abundant light hydrogen makes the enrichment of the heavy isotopes extremely challenging. State-of-the-art separation methods based on chemical exchange remain energy-consuming processes. In this thesis, density functional and ab initio methods are used to make several contributions to the investigation of one alternative approach to isotope separation: the isotopologue-selective adsorption of hydrogen at undercoordinated metal sites based on the different zero-point energy of adsorption of the isotopologues.

Because the zero-point energy is proportional to the curvature of the potential energy surface, which in turn correlates with the adsorption energy, stronger adsorption should in principle also lead to higher selectivity. Therefore, in the first part, the prerequisites for a high adsorption energy are investigated. It is concluded that main contributors are the chemical nature of the metal site (presence of d orbitals) and very acute ligand-metal-ligand angles, whereas the nature of the ligands seems to play a minor role.

The second part focuses on the selectivity-enhancing effect of confinement introduced by a pore around the adsorption site. It is found that confinement does not play a significant role in Cu(I)-MFU-4l. Although some confinement may be introduced via appropriate modifications of the linker, it is found that this comes at the cost of a sharp loss in H₂ affinity. Studying a more strongly binding model, it is nevertheless concluded that confinement can indeed significantly enhance H₂ isotopologue selectivity at very strong adsorption sites.

B₁₂X₁₁⁻ (X = H, F, Cl, Br, I, CN), a system showing very strong H₂ adsorption and a high D₂ /H₂ selectivity is investigated in the third part.

In the fourth part, the CoRE MOF database is screened for potential H₂-affine sites based on geometric criteria. Some promising adsorption site motifs are identified, studied with preliminary DFT calculations and their deeper investigation in future works is envisioned.

To conclude, this thesis advances the field of isotopologue-selective H₂ adsorption by identifying both general structural prerequisites for high selectivity as well as specific model systems and structural motifs worthy of further study.

The crystal structure of Sc3Ir4Si13+x (x = 0.22) [space group Pm3 ̅n, a = 8.4651(1) Å] is found to be a new disordered variant of the primitive cubic Yb3Rh4Sn13 Remeika prototype. The silicide is stable in the narrow temperature range of 1283-1397 °C and reveals metallic properties. The crystal structure of Sc4Ir7Ge6 [U4Re7Si6 type, space group Im3 ̅m, a = 8.1397(8) Å] is refined for the first time. The electronic band structure calculations reveal that the properties of this germanide can be explained based on the free electron gas model. Both compounds reveal close structural relationships to the simple perovskite structure.

Unusually high uranium (U) concentrations (up to 175 μg/L) have been measured in groundwater at depths between 400 and 650 m at the Forsmark site, eastern Sweden. Since it is unlikely that such high concentrations formed under the stagnant and low redox groundwater conditions that currently prevail, this study employs U-series isotopes to understand how the recent evolution (<1 Ma) of the flow system has influenced the observed U distribution. Material from fractures as deep as 700 m along the assumed flow route was subject to U-series disequilibrium (USD) measurements, as well as sequential extractions (SE) and U redox-state analyses that revealed the U-series activity ratios in the bulk and soluble fraction of the fracture precipitates. Uranium isotope data collected over several years of annual groundwater monitoring were scrutinized to evaluate the U sources and U exchange in fractures located in high-U groundwater sections. Numerical simulations with the experimental data were used to study evolution of U-series isotope composition in a fracture in the highest U section at ~500 m depth under various U mobility scenarios. The results show that U redistribution in fractures with certain dissolution/deposition flux ratios during periodic water intrusions, driven by glaciation and deglaciation events during the last 120 ka, can explain the U anomaly in the groundwater.

Proceedings of Machine Learning Research

Helmholtz AI has been available for members of ARD since its inception 2019/20. In this presentation, I'd like to present the current status of Helmholtz AI consultancy for matter research in Helmholtz. I'd provide sneak previews into past and ongoing vouchers we embarked upon for the accelerator physics community. Last but not least, I'll discuss challenges we faced along the way and will highlight some future directions if time allows.

A jupyter notebook that can predict the shoe size of a person based on their gender, height and weight. This is a notebook meant for training purposes to show case how public data can be used to train a machine learning predictor.

This notebook uses a public crowd-sourced dataset from https://doi.org/10.5281/zenodo.5541145 to conduct the training.

This data set was crowdsourced at the 2021 Helmholtz MT ARD ST3 meeting from attendants of the Machine Learning Tutorial on Sep 30, 2021. For more details on the event, see
https://indico.desy.de/event/28823/

The talk gives an overview on the publication of an (PaN) experiment in general, including data and software publication. An additional overall workflow describes the dependencies between all data objects with the aim to create a comprehensible experiment. The live demo introduces our training catalogue developed in WP5 with the special workflow feature.

A definition of the most suitable training materials for PaN communities in accordance with the requirements and recommendations made by the targeted e-platform providers.

A demonstrator for using e-learning platforms was developed and provided by HZDR in the frame of the ExPaNDS project.

Polyamines are highly attractive vectors for tumor targeting, particularly with regards to the development of radiolabeled probes for imaging by positron emission (PET) and single-photon emission computed tomography (SPECT). However, the synthesis of selectively functionalized derivatives remains challenging owing to the presence of multiple amino groups of similar re-activity. In this work, we established a synthetic methodology for the selective mono-fluorobenz(o)ylation of various biogenic diamines and polyamines as lead compounds for the perspective development of substrate-based radiotracers for targeting polyamine-specific membrane transporters and enzymes such as transglutaminases. To this end, the polyamine scaffold was constructed by solid-phase synthesis of the corresponding oxopolyamines and subsequent re-duction with BH₃/THF. Primary and secondary amino groups were selectively protected using Dde and Boc as protecting groups, respectively, in orientation to previously reported proce-dures, which enabled the selective introduction of the reporter groups. For example, N¹-FBz-spermidine, N⁴-FBz-spermidine, N⁸-FBz-spermidine, and N¹-FBz-spermine and N⁴-FBz-spermine (FBz=4-fluorobenzoyl) were obtained in good yields by this approach. The advantages and disadvantages of this synthetic approach are discussed in detail and its suitability for radiolabeling was demonstrated for the solid-phase synthesis of N¹-[¹⁸F]FBz-cadaverine.

Species’ life-history traits have a wide variety of applications in ecological and conservation research, particularly when assessing threats. The development and growth of global species’ trait databases are critical for improving trait-based analyses; however, it is vital to understand the gaps and biases in the available data.
We reviewed bat wing morphology data, specifically mass, wingspan, wing area, wing loading, and aspect ratio, to identify issues with data reporting and ambiguity. Additionally, we aimed to assess taxonomic and geographic biases in trait data coverage. We found that most studies used similar field methodology, but that data reporting and quality were inconsistent/poor. Additionally, we noted several issues regarding semantic ambiguity in trait definitions, specifically around what constitutes wing area. Globally, we found that bat wing morphology trait coverage was low. Only six bat families had ≥40% trait coverage, and, of those, none consisted of more than 11 species in total. We found similar biases in trait coverage across International Union for Conservation of Nature Red List categories, with threatened species having lower coverage.
Geographically, North America, Europe, and the Indomalayan regions exhibited higher overall trait coverage, while both the Afrotropical and Neotropical ecoregions showed poor trait coverage.
The underlying biases and gaps in bat wing morphology data have implications for researchers conducting global trait-based assessments. Implementing imputation techniques may address missing data, but only for smaller regional subsets with substantial trait coverage. Due to generally low overall trait coverage, increasing species’ representation in the database should be prioritised. We suggest adopting an Ecological Trait Standard Vocabulary to reduce semantic ambiguity in bat wing morphology traits, to improve data compilation and clarity. Additionally, we advocate that researchers adopt an Open Science approach to facilitate the growth of a bat wing morphology trait database.

Autonomous vehicles (AV) are expected to play a key role in the future of transportation, introducing a disruptive yet potentially beneficial change for vehicle-wildlife interactions. However, this assumption has not been critically examined. Here, we introduce a new conceptual framework covering the intersection between AV technological innovation and wildlife conservation to reduce wildlife-vehicle collisions. We suggest future research within this framework to focus on developing robust warning systems and animal detection methods for AV systems, and to incorporate wildlife-vehicle interactions into decision-making algorithms. With large-scale deployment a looming reality, it is vital to incorporate conservation and sustainability into the societal, ethical, and legal implications of AV technology. We appeal for further debate and interdisciplinary collaborations between scientists, developers, and policymakers.

In recent years, short, pulsed laser ablation has been gaining popularity for machining small scale test geometries from bulk samples and for efficient serial sectioning. These laser-based techniques are being added to the toolbox in material science, which makes it necessary to understand the changes in the material that occur from the laser-material interaction. Positron annihilation spectroscopy is a unique, nondestructive technique to investigate small defects in materials difficult to investigate by other tools. In this work, Doppler broadening and positron lifetime annihilation spectroscopy are utilized to help quantify the damage in materials treated with short, pulsed lasers. Using a femtosecond laser on single crystal silicon, this manuscript shows that clusters of vacancy-like defects and small voids increase systematically with laser power. The damage induced by the laser can also reach to micrometer depths.

The incident ion defines the interaction mechanism with the sample surface caused by the energy deposition and thus has significant consequences on resulting nanostructures [1]. Therefore, we have extended the FIB technology towards the stable delivery of multiple ion species by liquid metal alloy ion sources (LMAIS) [2].
These LMAIS provides single and multiple charged ion species of different masses. As an example we introduce the GaBiLi LMAIS [3]. Such “universal” source enables high resolution imaging with light Li ions and sample modification with Ga or heavy polyatomic Bi clusters, all coming from the same ion source. Light ions are of
increasing interest due to the available high resolution in the nanometer range and their special chemical and physical behavior in the substrate. We compare helium and neon ion beams from a helium ion microscope with beams such as lithium, boron, and silicon, obtained from a mass-separated FIB using a LMAIS with respect
to the imaging and milling resolution, as well as the current stability [4]. The bombardment of solids by poly-atomic (cluster) ions leads to nonlinear collision cascades in near-surface regions. In comparison with linear cascades by monoatomic ions, much higher energy deposition occurs up to local surface melting [5]. Here, we also report the study on the sputter yield of Si under the bombardment by atomic Bi+ and cluster Bin+ (n = 2-4) ions with the same specific energy related to one incidence single atom [6].
[1] P. Mazarov, V. Dudnikov, A. Tolstoguzov, Electrohydrodynamic emitters of ion beams, Phys. Usp. 63
(2020) 1219.
[2] L. Bischoff, P. Mazarov, L. Bruchhaus, and J. Gierak, Liquid Metal Alloy Ion Sources – An Alternative
for Focused Ion Beam Technology, Appl. Phys. Rev. 3 (2016) 021101.
[3] W. Pilz, N. Klingner, L. Bischoff, P. Mazarov, and S. Bauerdick, Lithium ion beams from liquid metal
alloy ion sources, JVSTB 37(2), Mar/Apr (2019) 021802.
[4] N. Klingner, G. Hlawacek, P. Mazarov, W. Pilz, F. Meyer, L. Bischoff, Imaging and Milling Resolution
of Light Ion Beams from HIM and Liquid Metal Alloy Ion Source driven FIBs, Beilstein J. Nanotechnol. 11
(2020) 1742.
[5] L. Bischoff, K.-H. Heinig, B. Schmidt, S. Facsko, and W. Pilz, Self-organization of Ge nanopattern under
erosion with heavy Bi monomer and cluster ions, Nucl. Instr. Meth. B 272 (2012) 198.
[6] A. Tolstogouzov, P. Mazarov, A. Ieshkin, S.Belykh, N. Korobeishchikov, V. Pelenovich, D.J. Fu,
Sputtering of silicon by atomic and cluster bismuth ions: An influence of projectile nuclearity and specific
kinetic energy on the sputter yield, Vacuum 188 (2021) 110188.

Focused Ion Beam (FIB) processing is established as a well-suited and promising technique in R&D in nearly all fields of nanotechnology for patterning and prototyping on the μm-scale and below. Liquid Metal Alloy Ion Sources (LMAIS) represent an alternative to expand the FIB application fields beside all other source concepts [1]. Due to the interest on light elements, especially boron, various alloys were investigated and characterized. In this contribution we will describe Co31Nd64B5 as the most promising alloy in more detail. The mass spectrum of such a source was obtained in a VELION FIB-SEM system (Raith GmbH) [2]. The source operation life time was longer than 600 μAh and a first imaging characterization showed a lateral resolution of (30 ± 5) nm so far. This LMAIS is suited for several mass-filtered FIB applications like implantation, high rate sputtering, surface patterning or ion lithography [3]. The switching between the certain ion species. B – very light, suitable for ion lithography or writing p-type doping. Co – medium mass for applications in the field of nano-magnetics or CoSi2 for ion beam synthesis of conductive nano-structures on Si. Finally Nd as double charged heavy ion for ion sputtering. The change between ion species can be done in seconds and leads to remarkable expansion of the application spectrum of FIB technology.
[1] L. Bischoff, P. Mazarov, L. Bruchhaus, and J. Gierak, Liquid Metal Alloy Ion Sources - An Alternative for Focused Ion Beam Technology; Appl. Phys. Rev. 3 (2016) 021101.
[2] L. Bischoff, N. Klingner, P. Mazarov, W. Pilz, and F. Meyer, Boron Liquid Metal Alloy Ion Sources for special FIB applications, JVST B 38 (2020) 042801.
[3] L. Bruchhaus, P. Mazarov, L. Bischoff, J. Gierak, A. D. Wieck, and H. Hövel, Comparison of Technologies for Nano Device Prototyping with a Special Focus on Ion Beams – A Review,
Appl. Phys. Rev. 4 (2017), 011302.

The SARS-CoV-2 virus has spread around the world with over 100 million infections to date, and currently many countries are fighting the second wave of infections. With neither sufficient vaccination capacity nor effective medication, non-pharmaceutical interventions (NPIs) remain the measure of choice. However, NPIs place a great burden on society, the mental health of individuals, and economics. Therefore the cost/benefit ratio must be carefully balanced and a target-oriented small-scale implementation of these NPIs could help achieve this balance. To this end, we introduce a modified SEIRD-class compartment model and parametrize it locally for all 412 districts of Germany. The NPIs are modeled at district level by time varying contact rates. This high spatial resolution makes it possible to apply geostatistical methods to analyse the spatial patterns of the pandemic in Germany and to compare the results of different spatial resolutions. We find that the modified SEIRD model can successfully be fitted to the COVID-19 cases in German districts, states, and also nationwide. We propose the correlation length as a further measure, besides the weekly incidence rates, to describe the current situation of the epidemic.

Chalcogenide phase change materials reversibly switch between non-volatile states with vastly different optical properties, enabling novel active nanophotonic devices. However, a fundamental understanding of their laser-switching behavior is lacking and the resulting local optical properties are unclear at the nanoscale. Here, we combine infrared scattering-type scanning near-field optical microscopy (SNOM) and Kelvin probe force microscopy (KPFM) to investigate four states of laser-switched Ge3Sb2Te6 (as-deposited amorphous, crystallized, reamorphized, and recrystallized) with nanometer lateral resolution. We find SNOM especially sensitive to differences between crystalline and amorphous states, while KPFM has higher sensitivity to changes introduced by melt-quenching. Using illumination from a free-electron laser, we employ that far-infrared (THz) SNOM is more sensitive to free charge carriers compared to mid-infrared SNOM and prove that the local conductivity of crystalline states depends on the switching process. This insight into the local switching of optical properties is essential for developing active nanophotonic devices.

Background: We analyse the benefit of 4D robust plan optimization (RO) for proton therapy treatments of NSCLC patients with pronounced breathing-induced anatomical variations.

Methods: Eight NSCLC patients with relevant maximal intrafractional motion of the primary (CTVp; 5.6-24.5mm) and/or nodal CTV (CTVn; 5.8-17.3mm) on the planning 4DCT (pCT) were included. We optimized three robust normo-fractionated plans with a criterion of 5mm setup and 3.5%+2mm range uncertainty: RO on the AverageCT with iGTVp density override (3DRO); RO on the AverageCT and three 4DCT phases (4DRO3); and RO on the AverageCT and all eight 4DCT phases (4DRO8). Setup and range error scenarios were analysed on the pCT. To assess robustness against intra- and inter-fractional changes, 4D doses were calculated on the pCT and up to two control 4DCTs (cCTs) assuming equal weights between breathing phases. Interplay effects were simulated on the pCT from patient breathing signals and machine logfiles of plan deliveries with and without 5 layered rescans. Fractionation effects were emulated by accumulating four interplay scenarios with different starting times.

Results: All nominal plans fulfilled target coverage (D98%>95%) and OAR sparing; CTVp/CTVn coverage failed setup and range robustness in 12%/35% (3DRO), 14%/18% (4DRO3) and 13%/20% (4DRO8) of the scenarios (Fig1a), respectively. 4D dose target coverage on the pCT was >94% for all plans; interfractional changes in the cCTs reduced the CTVp coverage by about 2pp (Fig1b). Interplay analyses (Fig1c) revealed a mean CTVp/CTVn coverage loss by 3.4pp/2.4pp, 3.0pp/2.3pp, and 2.9pp/3.2pp in single scenarios of 3DRO, 4DRO3 and 4DRO8 plans, respectively. D98% values were improved on average by 1.0pp with rescanning, but were even worsened in some scenarios. Irrespective of rescanning, the simulated fractionation fullfilled the target coverage in all cases.

Conclusion: 3DRO and 4DRO showed similar robustness against different motion effects. 4DRO provides benefits for some patients, but 3DRO demands less workload.

In this chapter, we will present and summarize the latest innovative materials science approaches devoted to increase the CSP plant efficiency by implementing higher operation temperatures and reducing the levelized costs of electricity (LCOE). The chapter is organized as follows: The first section provides statistical data (Section 13.3.1) and the basic knowledge (Section 13.3.2) necessary to understand the state-of-the-art and the recent R&D directions of the field “high-temperature solar thermal applications”. In the second section 13.2 we introduce the concept of solar selectivity. Based on realistic operational parameters of CSP plants, their potentials and limitations are discussed and graphically illustrated. State-of-the-art results from the last decade are briefly reviewed in the third section for: absorber paints (Section 13.3.1), solar selective coatings (SSCs) (Section 13.3.2), and volumetric receivers (Section 13.3.3). The fourth Section 13.4 focuses on the need of comparable stability studies of newly developed SSCs and materials along with the demand and the criteria for standardized characterization protocols.

We present our contribution to the HECKTOR 2021 challenge.
We created a Survival Random Forest model based on clinical features, and a few radiomics features that have been extracted with and without using the given tumor masks, for Task 3 and Task 2 of the challenge, respectively.
To decide on which radiomics features to include into the model, we proceeded both to automatic feature selection, using several established methods, and to literature review of radiomics approaches for similar tasks.
Our best performing model includes one feature selected from the literature (Metabolic Tumor Volume derived from the FDG-PET image), one via stability selection (Inverse Variance of the Gray Level Co-occurrence Matrix of the CT image), and one selected via permutation-based feature importance (Tumor Sphericity).
This hybrid approach turns-out to be more robust to overfitting than models based on automatic feature selection.
We also show that simple ROI definition for the radiomics features, derived by thresholding the Standard Uptake Value in the FDG-PET images, outperforms the given expert tumor delineation in our case. Team name on the AIcrowd platform: ia-h-ai.

Establishing precise control over the beam parameters of laser-accelerated ions from the interaction of ultrashort ultra-high intensity (UHI) laser pulses with ultrathin foils has been the major goal of the last 20 years since the first description of the TNSA process. Especially the quest for repeatable, highest maximum energies continues to be challenging as the spatiotemporal coupling of laser-pulse- and target parameters down to the femtosecond-nanometer level was found to be decisive for the overall acceleration performance. In particular, precise control and metrology of the driving UHI laser pulses are paramount to achieving this goal. We present a multi-parameter-space study, bridging the scales from picosecond preplasma formation over transient, non-equilibrium dynamics of the tens of femtosecond laser duration down to attosecond plasma oscillations performed through 1D– up to 3D particle-in-cell simulations. By taking into account realistic temporal intensity contrast features of the last picosecond prior and up to the first picosecond after the main pulse peak, we show how temporal pulse shaping optimizes the TNSA process.

Although epithermal Pb-Zn-Ag-(Au) vein-hosted mineralisation in the Freiberg District, Germany, has been widely studied, closely associated wall rock alteration remains hardly understood. In order to deduce alteration stages in the proximity to mineralised veins, suites of wall rock samples ranging from least altered to intensely altered were studied from two localities in the central part of the district in order to describe and quantify the effects of hydrothermal wall rock alteration.

Least altered host rocks at both localities are medium to coarse- grained biotite –plagioclase orthoclase augengneisses. In weakly altered samples the foliation, and the primary assemblage are well preserved with typical alteration assemblages comprising of fine-grained carbonate, kaolinite, epidote, sericite and chlorite. This alteration assemblage dominates also in moderately altered samples, with metamorphic quartz and the original foliation partly preserved. Intensively altered samples, in contrast, comprise a massive fabric with globular quartz and fine-grained sericite that are very finely intergrown arsenopyrite and/or pyrite occur finely disseminated in this alteration assemblage. Fe-Mn-rich carbonates also occur in the matrix or as thin veinlets in the altered wall rock. In hand specimen, this strongly sericitized rock is of light green to yellow colour.

Hydrothermal alteration related to vein-hosted magmatic-hydrothermal mineralization in the Freiberg District is best described as fabric destructive with distinct discoloration, an effect that can be simply detected visually in core. Sericitization and silicification are dominant – and appear limited to the immediate vicinity around and within relevant structural zones and veins. Visual core inspection, possibly complemented by hyperspectral drill core scanning and whole rock geochemistry (by pXRF) are simple tools that can be used to trace this alteration during ongoing exploration efforts in the district.

In this work thin films of 5,10,15,20-tetraphenylporphyrin (H2TPP) and 5,10,15,20-tetrakis(4-methoxyphenyl)porpyhrin (H2TMPP)) were prepared by organic molecular beam deposition (OMBD). In addition, spin coating was applied as an alternative preparation technique for thin films of H2TPP to investigate the influence of the deposition method on the optical properties. The preservation of the molecular structure was proven by comparative Raman spectroscopy studies between films and powder. Modelling of the spectroscopic ellipsometry data yields a uniaxial anisotropy of the optical constants for the films of both molecules deposited by OMBD, which was used to determine the relative orientation of the molecules with respect to the substrate. The effect of the storage in air on the optical properties of the OMBD films was investigated using the example of H2TMPP. The molecular order in the films was found to decrease while the film roughness increased compared to samples stored in nitrogen.

The ion-induced nanoscale pattern formation on a crystalline Ge(001) surface is observed in-situ by means of Grazing Incidence Small Angle X-ray Scattering (GISAXS). Analysis of the GISAXS intensity maps yields the temporal develoment of geometric parameters characterizing the changing pattern morphology. In comparison with theoretical predictions and with simulations of the patterning process based on a continuum equation we find good agreement for the temporal evolution of the polar facet angle, characteristic length, and surface roughness in the non-linear regime. To achieve this agreement, we included an additional term in the continuum equation which adjusts the pattern anisotropy.

The spontaneous crystal surface reconstruction of M-plane Al₂O₃ is employed for nanopatterning and nanofabrication in various fields of research including, among others, magnetism, superconductivity, and optoelectronics. However, investigating this reconstruction process from a planar surface to one with a nanoscale ripple topography is challenging, since it occurs at high temperatures above approximately 1000 °C. This contribution presents an approach combining ex-situ Atomic Force Microscopy with in-situ and simulated Grazing Incidence Small Angle X-ray Scattering to further elucidate this morphological transition. It provides time-resolved information on all relevant morphological characteristics required to trace the surface topography during recon-
struction and thereby offers a comprehensive picture of this process on a nanometer scale.

Europes’ journey towards a sustainable and digitized future relies fundamentally on the secured supply with critical raw materials. Lithium, Rare Earths, Indium and Tungsten, to name a few, are fundamental requisites for green and smart technologies, e-mobility and the energy transition. Securing the access to such materials is one of the fundamental questions for Europes ambition to deliver the Green Deal. Fast, versatile and accurate but at the same time socially acceptable and less invasive mineral exploration technologies are required to meet this goal. Innovative sensors and acquisition platforms for spectral imaging allow to gain insights on the composition of materials without destroying or even touching them. The complexity, diversity and sheer amount of respective data produced in a typical exploration scenario require a joint understanding of geoscience, image processing and machine learning to retrieve geologically meaningful results in a reasonable time. The presentation will give an overview on our current research highlighting important challenges in modern mineral exploration in regards to image processing, multi-sensor data fusion, data classification and real-time processing.

Drohnen unterstützen heutzutage viele Anwendungsfelder als preiswerte und flexible Flugplattformen. Durch die fortschreitende Entwicklung miniaturisierter Sensorik können Drohnen inzwischen auch für komplexe Observierungsaufgaben eingesetzt werden. Sie unterstützen auf diese Weise Wissenschaft und Industrie bei der Analyse schwer erreichbarer Ziele, zum Beispiel in Bergbau, Landwirtschaft oder Bauindustrie. Der notwendige Kompromiss zwischen Zuladung und Flugzeit ist dabei für die zivile Drohnenanwendung nach wie vor eine große Herausforderung. Mit seiner neuesten Projektidee zu autonomen, selbstorganisierten Drohnenverbänden will die Abteilung Erkundung des Helmholtz-Institutes Freiberg für Ressourcentechnologie Abhilfe schaffen: Scouting-Drohnen mit langer Flugzeit und leichten multispektralen Sensoren übernehmen eine Vorab-Analyse des Zielgebietes in Echtzeit. Anhand der Ergebnisse koordinieren sie selbsttätig weitere Drohnen ihres Verbandes für eine detaillierte Analyse ausgewählter kleinerer Zielpolygone. Jene mit schwereren, aber genaueren Sensoren ausgerüsteten Drohnen sparen so nicht nur Flugzeit ein, sondern nehmen auch nur dort detaillierte Daten auf wo sie wirklich benötigt werden. Neben der Entwicklung der Drohnen- und Multisensortechnologie sind Echtzeitverarbeitung und künstliche Intelligenz die Kernherausforderungen des Projektes.

Independent of the application field, spatially detailed information is commonly provided in the form of image data. Accordingly, major developments in image processing and artificial intelligence (AI) for image data interpretation are based on an image-like data structure, i.e. a spatially two-dimensional data grid with a custom number of informative layers. While sufficient for large-scale geographical data, this approach has major flaws when applied in any oblique-angle scenario, in particular as it inherently distorts the spatial characteristics of the observed target (virtual vs. real-world neighborhood relationships, occlusions). Todays’ most crucial image data applications (e.g., resources, energy, mobility, medicine), however, heavily rely on the accurate interpretation of the spatial relationship of objects in all three dimensions. It has been shown that the upscaling of 2D-images to multi-feature attributed 3D point clouds boosts the interpretational value of the dataset. This approach is not only beneficial for the fusion of image data with 3D-information (such as orientation, shape, and surface roughness), but also offers a straightforward solution for the fusion of higher dimensional multi-sensor data. Although point clouds or meshes are routinely used as 3D analogues of real-world targets, the processing of multi-feature point clouds in terms of clustering, classification or material characterization is still in its infancy. Innovative AI approaches such as PointNets or 3D-CNN have shown great potential for point cloud clustering using the spatial relationships of the individual points. However, classifications based on both spatial and auxiliary, high-dimensional point information such as spectral signatures or compositional characteristics is yet to be developed. The proposed project aims at the development of advanced machine (deep) learning approaches to fill this exact gap. These approaches comprise both the challenging fusion of multiple sensors as well as the subsequent classification and segmentation. Besides the algorithm design, the testing on representative scenarios from different application fields is a main work package, including the creation of reusable benchmark datasets for the validation and future development of algorithms. If successful, the project will improve the characterization of objects and surfaces for a wide range of potential applications such as exploration and mining, recycling, autonomous systems, quality assessment, sorting systems or detection of falsified objects. From a resource perspective, an enhanced material characterization will directly contribute to making processes more material and energy efficient. Regarding autonomous systems, the project will advance the research and implementation of methods for robust sensor fusion of multimodal sensors. Due to the versatility in application, the project outcome could support any process that requires a multi-sensor-based discrimination of objects and materials.

Uniform quasi-one-dimensional integer spin compounds are of interest as a potential realization of the Haldane conjecture of a gapped spin liquid. This phase, however, has to compete with magnetic anisotropy and long-range ordered phases, the implementation of which depends on the ratio of interchain J′ and intrachain J exchange interactions and both uniaxial D and rhombic E single-ion anisotropies. Strontium nickel selenite chloride, Sr₂Ni(SeO₃)₂Cl₂, is a spin-1 chain system which passes through a correlations regime at T_max ~ 12 K to long-range order at T_N = 6 K. Under external magnetic field it experiences the sequence of spin-flop at B_c1 = 9.0 T and spin-flip transitions B_c2 = 23.7 T prior to full saturation at B_sat = 31.0 T. Density functional theory provides values of the main exchange interactions and uniaxial anisotropy which corroborate the experimental findings. The values of J′/J = 0.083 and D/J = 0.357 place this compound into a hitherto unoccupied sector of the Sakai-Takahashi phase diagram.

Part of the process to ensure the safety of radioactive waste disposal is the predictive modelling of the solubility of all relevant toxic components in a complex aqueous solution. To ensure the reliability of thermodynamic equilibrium modelling as well as to facilitate the comparison of such calculations done by different institutions it is necessary to create a mutually accepted thermodynamic reference database. To meet this demand several institutions in Germany joined efforts and created THEREDA [1].

THEREDA is a suite of programs at the base of which resides a relational databank. Special emphasis is put on thermodynamic data along with suitable Pitzer coefficients, which allow for the calculation of solubilities in high-saline solutions. Registered users may either view single thermodynamic data and Pitzer interaction parameters or download ready-to-use parameter files for the geochemical speciation codes PHREEQC, Geochemist’s Workbench, CHEMAPP, or TOUGHREACT. The dataset can also be downloaded in a generic JSON-format to allow the import into other codes. The database can be accessed via the World Wide Web: www.thereda.de

Prior to release, the released part of the database is subjected to many tests. Results are compared to results from earlier releases and among the different codes. This is to ensure that by additions of new and modification of existing data no adverse side effects on calculations are caused. Furthermore, our website offers an in-creasing number of examples for applications, including graphical representation, which can be filtered by com-ponents of the calculated system.

REFERENCES
[1] Moog, H. C., Bok, F., Marquardt, C. M., and Brendler, V.: Disposal of Nuclear Waste in Host Rock formations featuring high-saline solutions - Implementation of a Thermodynamic Reference Database (THEREDA). Appl. Geochem., 55, 72-84, 2015

The effects of hydrogen absorption on the effective magnetization (4πM_eff), gyromagnetic ratio (γ), Gilbert damping constant (α_G), and the inhomogeneous linewidth broadening in Py(x)/Y(16 nm)/Pd(15 nm) trilayer films (x = 2, 3, 5, 8, 10, 20, 40 nm) were investigated with ferromagnetic resonance (FMR), transmission electron microscopy, and vibrating sample magnetometry. In the presence of a hydrogen atmosphere, the samples show a reduction of their FMR linewidth which is found to stem purely from a reduction of the inhomogeneous linewidth broadening. This is attributed to a rearrangement of atoms at the Py/Y interface in the presence of hydrogen, making the Py/Y interface more homogeneous. In addition, a reduction of 4πM_eff was seen for all samples in the hydrogen atmosphere which is typical for an increase of the interfacial perpendicular magnetic anisotropy at the Py/Y interface.

We study the trident process in laser pulses. We provide exact numerical results for all contributions, including the difficult exchange term. We show that all terms are in general important for a short pulse. For a long pulse, we identify a term that gives the dominant contribution even if the intensity is only moderately high, a0≳1, which is an experimentally important regime where the standard locally constant field (LCF) approximation cannot be used. We show that the spectrum has a richer structure at a0∼1, compared to the LCF regime a0≫1. We study the convergence to LCF as a0 increases and how this convergence depends on the momentum of the initial electron. We also identify the terms that dominate at high energy.

A large non-saturating magnetoresistance has been observed in several nonmagnetic topological Weyl semi-metals with high mobility of charge carriers at the Fermi energy. However, ferromagnetic systems rarely display a large magnetoresistance because of localized electrons in heavy d bands with a low Fermi velocity. Here, we report a large linear non-saturating magnetoresistance and high mobility in ferromagnetic MnBi. MnBi, unlike conventional ferromagnets, exhibits a large linear non-saturating magnetoresistance of 5000% under a pulsed field of 70 T. The electrons and holes’ mobilities are both 5000 cm²V⁻¹s⁻¹ at 2 K, which are one of the highest for ferromagnetic materials. These phenomena are due to the spin-polarised Bi 6p band’s sharp dispersion with a small effective mass. Our study provides an approach to achieve high mobility in ferromagnetic systems with a high Curie temperature, which is advantageous for topological spintronics.

Higher-order tree-level processes in strong laser fields, i.e., cascades, are in general extremely difficult to calculate, but in some regimes the dominant contribution comes from a sequence of first-order processes, i.e., nonlinear Compton scattering and nonlinear Breit-Wheeler pair production. At high intensity the field can be treated as locally constant, which is the basis for standard particle-in-cell codes. However, the locally-constant-field (LCF) approximation and these particle-in-cell codes cannot be used when the intensity is only moderately high, which is a regime that is experimentally relevant. We have shown that one can still use a sequence of first-order processes to estimate higher orders at moderate intensities provided the field is sufficiently long. An important aspect of our new “gluing” approach is the role of the spin and polarization of intermediate particles, which is more nontrivial compared to the LCF regime.

The European XFEL delivers up to 27000 intense (>10¹² photons) pulses per second, of ultrashort (≤50 fs) and transversely coherent X-ray radiation, at a maximum repetition rate of 4.5 MHz. Its unique X-ray beam parameters enable groundbreaking experiments in matter at extreme conditions at the High Energy Density (HED) scientific instrument. The performance of the HED instrument during its first two years of operation, its scientific remit, as well as ongoing installations towards full operation are presented. Scientific goals of HED include the investigation of extreme states of matter created by intense laser pulses, diamond anvil cells, or pulsed magnets, and ultrafast X-ray methods that allow their diagnosis using self-amplified spontaneous emission between 5 and 25 keV, coupled with X-ray monochromators and optional seeded beam operation. The HED instrument provides two target chambers, X-ray spectrometers for emission and scattering, X-ray detectors, and a timing tool to correct for residual timing jitter between laser and X-ray pulses.

We study nonlinear trident in laser pulses in the high-energy limit, where the initial electron experiences, in its rest frame, an electromagnetic field strength above Schwinger’s critical field. At lower energies the dominant contribution comes from the “two-step” part, but in the high-energy limit the dominant contribution comes instead from the one-step term. We obtain new approximations that explain the relation between the high-energy limit of trident and pair production by a Coulomb field, as well as the role of the Weizsäcker-Williams approximation and why it does not agree with the high-χ limit of the locally-constant-field approximation. We also show that the next-to-leading order in the large-a0 expansion is, in the high-energy limit, nonlocal and is numerically very important even for quite large a0. We show that the small-a0 perturbation series has a finite radius of convergence, but using Padé-conformal methods we obtain resummations that go beyond the radius of convergence and have a large numerical overlap with the large-a0 approximation. We use Borel-Padé-conformal methods to resum the small-χ expansion and obtain a high precision up to very large χ. We also use newer resummation methods based on hypergeometric/Meijer-G and confluent hypergeometric functions.

We study the photon trident process, where an initial photon turns into an electron-positron pair and a final photon under a nonlinear interaction with a strong plane-wave background field. We show that this process is very similar to double Compton scattering, where an electron interacts with the background field and emits two photons. We also show how the one-step terms can be obtained by resumming the small- and large-\chiχ expansions. We consider a couple of different resummation methods, and also propose new resummations (involving Meijer-G functions) which have the correct type of expansions at both small and large \chiχ. These new resummations require relatively few terms to give good precision.

In a previous paper we showed how higher-order strong-field-QED processes in long laser pulses can be approximated by multiplying sequences of ‘strong-field Mueller matrices’. We obtained expressions that are valid for arbitrary field shape and polarization. In this paper we derive practical approximations of these Mueller matrices in the locally-constant- and the locally-monochromatic-field regimes. The spin and polarization can also change due to loop contributions (the mass operator for electrons and the polarization operator for photons). We derive Mueller matrices for these as well, for arbitrary laser polarization and arbitrarily polarized initial and final particles.

We propose a new approach to obtain the momentum expectation value of an electron in a high-intensity laser, including multiple photon emissions and loops. We find a recursive formula that allows us to obtain the O(αn) term from O(αn-1), which can also be expressed as an integro-differential equation. In the classical limit we obtain the solution to the Landau-Lifshitz equation to all orders. We show how spin-dependent quantum radiation reaction can be obtained by resumming both the energy expansion as well as the α expansion.

In a previous paper we proposed a new method based on resummations for studying radiation reaction of an electron in a plane-wave electromagnetic field. In this paper we use this method to study the electron momentum expectation value for a circularly polarized monochromatic field with a0=1, for which standard locally constant-field methods cannot be used. We also find that radiation reaction has a significant effect on the induced polarization, as compared to the results without radiation reaction, i.e., the Sokolov-Ternov formula for a constant field, or the zero result for a circularly monochromatic field. We also study the Abraham-Lorentz-Dirac equation using Borel-Padé resummations.

We performed soft x-ray spectroscopic studies of the ferrimagnet TbFe₅Al₇ with strong easy-plane anisotropy in pulsed magnetic fields up to 29 T along with bulk magnetization and magnetostriction measurements. We observed pronounced amplitude changes of x-ray magnetic circular dichroism and x-ray absorption spectra at the field-induced magnetic transition. This microscopically evidences the simultaneous rotation of the Tb 4 f and Fe 3d magnetic moments from a collinear ferrimagnetic order along the [100] axis to a state with the moments close to [010], the other easy-axis direction of the tetragonal lattice in magnetic fields applied along the [100] axis. We determined the magnetic-anisotropy constant of TbFe₅Al₇ by simulating the high-field macro- and microscopic magnetization process using a two-sublattice model.

In this work, we investigate the evolution and settling of magnon condensation in the spin-1/2 dimer system Sr₃Cr₂O₈ using a combination of magnetostriction in pulsed fields and inelastic neutron scattering in a continuous magnetic field. The magnetic structure in the Bose-Einstein condensation phase was probed by neutron diffraction in pulsed magnetic fields up to 39 T. The magnetic structure in this phase was confirmed to be an XY-antiferromagnetic structure validated by irreducible representational analysis. The magnetic phase diagram as a function of an applied magnetic field for this system is presented. Furthermore, zero-field neutron diffraction results indicate that dimerization plays an important role in stabilizing the low-temperature crystal structure.

In this paper, the full magnetization process demonstrated by the series of ferrimagnetic intermetallic compounds (Nd, Ho)₂Fe₁₄B and Ho₂FeB and their hydrides with the maximum possible hydrogen content (for the given crystal structure type) is studied theoretically and experimentally using megagauss magnetic fields. We observe field-induced phase transitions from the initial ferrimagnetic to the forced-ferromagnetic state in magnetic fields up to 130 T and describe the magnetization process analytically.We find a drastic decrease of the critical transition fields in the hydrogenated compounds. This is due to extremely strong, nearly twofold reduction of the R-Fe intersublattice exchange interaction because of the combined substitution and hydrogenation effects. A comparative analysis of the magnetization behavior for the system Ho₂Fe₁₇-H is also performed.

The compound SrCo₂P₂ is a Pauli paramagnet very close to ferromagnetic order. To study its electronic structure in close vicinity to the Fermi level, we report measurements of the de Haas–van Alphen effect in magnetic fields up to 35 T in combination with density-functional-theory band-structure calculations in different approximations. The resulting electronic band structure not only depends significantly on the choice of the functional, but also crucially on the exact values of the structural parameters that have been determined at low temperatures by synchrotron x-ray diffraction. We find the best correspondence between the measured and the calculated de Haas–van Alphen frequencies for the general gradient approximation functional and the structural parameters that were determined at 10 K. Although SrCo₂P₂ crystallizes in the uncollapsed tetragonal structure with a large P-P distance between the CoP₂ layers, we observe a rather three-dimensional Fermi-surface topology. We obtain a mass-enhancement factor of about 2 deduced from the ratio between experimental and calculated quasiparticle masses. The temperature dependence of the structural parameters leads to a significant reduction of the electronic density of states at the Fermi level and in comparison with the measured Sommerfeld coefficient to an overall mass renormalization in line with our experiment.