Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

1. The extinction of 80% of megaherbivore (>1,000 kg) species towards the end of the Pleistocene altered vegetation structure, fire dynamics, and nutrient cycling worldwide. Ecologists have proposed (re)introducing megaherbivores or their ecological analogues to restore lost ecosystem functions and reinforce extant but declining megaherbivore populations. However, the effects of megaherbivores on smaller herbivores are poorly understood.

2. We used long-term exclusion experiments and multispecies hierarchical models fitted to dung counts to test 1) the effect of megaherbivore (elephant and giraffe) presence-absence on the occurrence (dung presence) and use intensity (dung-pile density) of mesoherbivores (2–1,000 kg), and 2) the extent to which the responses of each mesoherbivore species was predictable based on their traits (diet and shoulder height) and phylogenetic relatedness.

3. Megaherbivores increased the predicted occurrence and use intensity of zebras but reduced the occurrence and use intensity of several other mesoherbivore species. The negative effect of megaherbivores on mesoherbivore occurrence was stronger for shorter species, regardless of diet or relatedness.

4. Megaherbivores substantially reduced the expected total use intensity (i.e., cumulative dung density of all species) of mesoherbivores, but only minimally reduced the expected species richness (i.e., cumulative predicted occurrence probabilities of all species) of mesoherbivores (by <1 species).

5. Simulated extirpation of megaherbivores altered use intensity by mesoherbivores, which should be considered during (re)introductions of megaherbivores or their ecological proxies. Species’ traits (in this case shoulder height) may be more reliable predictors of mesoherbivores’ responses to megaherbivores than phylogenetic relatedness, and may be useful for predicting responses of data-limited species.

Homeothermy requires increased metabolic rates as temperatures decline below the thermoneutral zone, so homeotherms typically select microhabitats within or near their thermoneutral zones during periods of inactivity. However, many mammals and birds are heterotherms that relax internal controls on body temperature when maintaining a high, stable body temperature is energetically costly. Such heterotherms should be less tied to microhabitats near their thermoneutral zones, and because heterotherms spend more time in torpor and expend less energy at colder temperatures, heterotherms may even select microhabitats in which temperatures are well below their thermoneutral zones. We studied how temperature and daily torpor influence selection of diurnal roosts by a heterothermic bat (Myotis thysanodes). We (1) quantified the relationship between ambient temperature and daily duration of torpor, (2) simulated daily energy expenditure over a range of microhabitat (roost) temperatures, and (3) quantified the influence of roost temperature on roost selection. While warm roosts substantially reduced energy expenditure of simulated homeothermic bats, heterothermic bats modulated their use of torpor to maintain a constant level of energy expenditure over the course of a day. Daily torpor expanded the range of energetically economical microhabitats, such that roost selection was independent of roost temperature. Our work adds to a growing literature documenting functions of torpor beyond its historical conceptualization as a last-resort measure to save energy during extended or acute energetic stress.

Although being investigated for more than 70 years by various methods, the uranyl(VI)–citrate (U(VI)–Cit) system still reveals interesting structural and spectroscopic features. The aqueous chemistry of the system is complex, as evidenced by the still controversial discussions on speciation and structures.

Upon complexation, a chiral center is induced in Cit’s central carbon, yielding two diastereomeric pairs of enantiomers, whereupon the 2:2 complexes exhibit syn- and anti-configured isomers. In fact, the combination of ¹⁷O-NMR (at natural abundance) and DFT calculations allowed an unambiguous discrimination. Hereby symmetry and especially deviation from regular pentagonal bipyramidal coordination geometry affect the O=U=O entities’ (O_yl) chemical shifts. In aqueous solution, the syn-isomer is favored, in contrast to the preferably crystallizing anti-isomer. Both isomers interconvert mutually with exchange rates of about 30 s^–¹ at −6 °C and 249 s^–¹ at 60 °C in acidic solution, corresponding to an activation barrier of about 24 kJ mol^–¹.[1]

At circumneutral conditions, above 3 mM uranyl(VI) citrate concentrations, two trimeric 3:3 U(VI)–Cit complex molecules associate upon sandwiching a metal ion (Mⁿ⁺) as a O=U=O→Mⁿ⁺ Lewis acid–base adduct. The coordination shell formed by the six (inner) O_yl restricts the size of the enclosed Lewis acid. Among the studied metal ions, only Na⁺, Ca²⁺, and La³⁺ with ionic radii close to 1.0 Å match the formed cavity, while Li⁺ is too small, and K⁺ and Rb⁺ are too large. This cavity constitutes an anhydrous environment that shields the Mⁿ⁺ from the aqueous phase, causing the sandwiched Na⁺ and La³⁺ to resonate 25 ppm and 430 ppm up-field relative to their corresponding aquo ions, respectively.
Upon increasing Mⁿ⁺ charge/radius ratio, the sandwiched Lewis acids more and more withdraw electron density from those O_yl acting as Lewis base, and thus the latter sense a remarkable de-shielding. Increasing the charge of the sandwiched cation from +1 to +3, Δδ_O between signals of the coordinating O_yl and the outer O_yl increases remarkably (12, 69, and 93 ppm, respectively), as the O=U=O units become progressively polarized.[2]

Literature:

[1] J. Kretzschmar et al., Inorg. Chem. 2021, 60, 7998.
[2] J. Kretzschmar et al., Chem. Commun. 2020, 56, 13133.

Bentonite is currently proposed as a potential backfill material for sealing high-level-radioactive waste in underground repositories due to its low hydraulic conductivity, self-sealing ability and high adsorption capability. High saline pore waters, high temperatures and the influence of microbes may cause mineralogical changes and affect the long-term performance of the bentonite barrier system. In this study, long-term diffusion batch experiments were carried out at 25°C and 90°C for one and two years using two different industrial bentonites (SD80 from Greece, B36 from Slovakia) and two types of aqueous solutions, which simulated a) Opalinus clay pore water with a salinity of 19 g·L-1 and b) saline cap rock solution with a salinity of 155 g·L-1. The bentonites were supplemented with and without organic substrates to study the microbial community and their potential influence on the bentonite mineralogy. Smectite alteration was dominated by metal ion substitutions, changes in layer charge and delamination during water-clay interaction. The degree of smectite alteration and changes in the microbial diversity depended largely on the respective bentonite and the experimental condition. Thus, the low charged SD80 with 17% tetrahedral charge showed nearly no structural change, whereas B36 as a medium charged smectite with 56% tetrahedral charge became more beidellitic with increasing temperature reacted in saline cap rock solution. Based on these experiments, the alteration of the smectite is mainly attributed to the nature of the bentonite, pore water chemistry and temperature. A significant microbial influence on the here analyzed parameters was not observed within the two years of experimentation, but should not be excluded, as the detected genera are known to potentially influence geochemical processes.

Titanium oxide films were deposited at room temperature and with no applied bias using a filtered cathodic vacuum arc (FCVA) system in a reactive oxygen environment. The dependence of film growth on two process parameters, the working pressure (Pw) and the O₂ partial pressure (pO₂), is described in detail. The composition, morphological features, crystalline structure, and optical properties of the deposited films were systematically studied by Rutherford Back Scattering (RBS), Scanning Electron Microscopy (SEM), X-Ray diffraction (XRD), Raman Spectroscopy, UV-vis spectroscopy, and spectroscopic ellipsometry. This systematic investigation allowed the identification of three different groups or growth regimes according to the stoichiometry and to the phase structure of the titanium oxide films. RBS analysis revealed that a wide range of TiO_x stoichiometries (0.6 < x < 2.2) were obtained, including oxygen-deficient, stoichiometric TiO₂ and oxygen-rich films. TiO, Ti₂O₃, rutile-type TiO₂, and amorphous TiO₂ phase structures could be achieved, as confirmed both by Raman and XRD. Therefore the results showed a highly versatile approach, in which different titanium oxide stoichiometries and crystalline phases especially suited for diverse optical applications can be obtained by changing only two process parameters, in a process at room temperature and without applied bias. Of particular interest are crystalline rutile films with high density to be used in ultra-high reflectance metal-dielectric multilayered mirrors, and reduced-TiO₂ rutile samples with absorption in the visible range as a very promising photocatalyst material.

We show the structural and optical properties of non-polar a-plane GaN epitaxial films modified by Si ion implantation. Upon gradually raising Si fluences from 5*10¹³ /cm² to 5*10¹⁵ /cm², the n-type dopant concentration gradually increases from 4.6*10¹⁸ /cm² to 4.5*10²⁰ /cm², while the generated vacancy density accordingly raises from 3.7*10¹³ /cm² to 3.8*10¹⁵ /cm². Moreover, despite that the implantation enhances structural disorder, the epitaxial structure of the implanted region is still well preserved which is confirmed by Rutherford backscattering channeling spectrometry measurements. The monotonical uniaxial lattice expansion along the a direction (out-of-plane direction) is observed as a function of fluences till 1*10¹⁵ /cm², which ceases at the overdose of 5*10¹⁵ /cm² due to the partial amorphization in the surface region. Upon raising irradiation dose, a yellow emission in the as-grown sample is gradually quenched, probably due to the irradiation-induced generation of non-radiative recombination centers.

The influence of ionic strength up to 3 mol/kg (background electrolytes NaCl or CaCl₂) on U(VI) sorption onto montmorillonite was investigated as function of pH_c in absence and presence of CO₂. A multi-method approach combined batch sorption experiments with spectroscopic methods (time-resolved laser-induced fluorescence spectroscopy (TRLFS) and in situ attenuated total reflection Fourier-transform infrared (ATR FT-IR) spectroscopy). In the absence of atmospheric carbonate, U(VI) sorption was nearly 99% above pH_c 6 in both NaCl and CaCl₂ and no significant effect of ionic strength was found. At lower pH, cation exchange was strongly reduced with increasing ionic strength. In the presence of carbonate, U(VI) sorption was reduced above pH_c 7.5 in NaCl and pH_c 6 in CaCl₂ system due to formation of aqueous UO₂(CO₃)_x ^(2-2x) and Ca₂UO₂(CO₃)₃ complexes, respectively, as verified by TRLFS. A significant ionic strength effect was observed due to the formation of Ca₂UO₂(CO₃)_{3 (aq)}, which strongly decreases U(VI) sorption with increasing ionic strength.
The joint analysis of determined sorption data together with literature data (giving a total of 213 experimental data points) allowed to derive a consistent set of surface complexation reactions and constants based on the 2SPNE SC/CE approach, yielding log K⁰ = 2.42 ± 0.04 (≡S^SOUO₂ ⁺), log K⁰ = −4.49 ± 0.7 (≡S^SOUO₂OH), and log K⁰ = −20.5 ± 0.4 (≡S^SOUO₂(OH)₃ ^2-). Ternary uranyl carbonate surface complexes were not required to describe the data. With this reduced set of surface complexes, an improved robust sorption model was obtained covering a broad variety of geochemical settings over wide ranges of ionic strengths and groundwater compositions, which subsequently was validated by an independent original dataset. This model improves the understanding of U(VI) retention by clay minerals and enables now predictive modeling of U(VI) sorption processes in complex clay rich natural environments.

Purpose: [⁶⁸Ga]Ga-PSMA-11 is a promising radiopharmaceutical for detecting tumour lesions in prostate cancer, but knowledge of the pharmacokinetics is limited. Dynamic PET-CT was performed to investigate the tumour detection and differences in temporal distribution, as well as in kinetic modelling of [⁶⁸Ga]Ga-PSMA-11 by tissue type.
Methods: Dynamic PET-CT over the lower abdomen and static whole-body PET-CT 80–90 min p.i. from 142 patients with biochemical recurrence were retrospectively analysed. Detection rates were compared to PSA levels. Average time-activity curves were calculated from tumour lesions and normal tissue. A three-compartment model and non-compartment model
were used to calculate tumour kinetics.
Results: Overall detection rate was 70.42%, and in patients with PSA > 0.4 ng/mL 76.67%. All tumour lesions presented the steepest standardised uptake value (SUV) incline in the first 7–8 min before decreasing to different degrees. Normal tissue presented with a low uptake, except for the bladder, which accumulated activity the steepest 15–16 min. p.i.. While all tumour
lesions continuously increased, bone metastases showed the steepest decline, resulting in a significantly lower SUV than lymph node metastases (60 and 80–90 min). Transport rate from the blood and tracer binding and internalisation rate were lower in bone metastases. Heterogeneity (fractal dimension) and vascular density were significantly lower in bone metastases.
Conclusion: Even at low PSA between 0.51 and 0.99 ng/mL, detection rate was 57%. Dynamic imaging showed a time window in the first 10 min where tumour uptake is high, but no bladder activity is measured, aiding accuracy in distinction of local recurrence. Kinetic modelling provided additional information for tumour characterisation by tissue type.

The interplay of structure, composition and electrical conductivity was investigated for Fe-doped SrTiO3 thin films prepared by pulsed laser deposition. Structural information was obtained by reciprocal space mapping while solution-based inductively-coupled plasma optical emission spectroscopy and positron annihilation lifetime spectroscopy were employed to reveal the cation composition and the predominant point defects of the thin films, respectively. A severe cation non-stoichiometry with Sr vacancies was found in films deposited from stoichiometric targets. The across plane electrical conductivity of such epitaxial films was studied in the temperature range of 250 - 720 °C by impedance spectroscopy. This revealed a pseudo-intrinsic electronic conductivity despite the substantial Fe acceptor doping, i.e. conductivities being several orders of magnitude lower than expected. Variation of PLD deposition parameters causes some changes of the cation stoichiometry, but the films still have conductivities much lower than expected. Targets with significant Sr excess (in the range of several percent) were employed to improve the cation stoichiometry in the films. The use of 7 % Sr-excess targets resulted in near-stoichiometric films with conductivities close to the stoichiometric bulk counterpart. The measurements show that a fine-tuning of the film stoichiometry is required in order to obtain acceptor doped SrTiO3 thin films with bulk-like properties. One can conclude that, although RSM experiments give a first hint whether or not cation non-stoichiometry is present, conductivity measurements are more appropriate for assessing SrTiO3 film quality in terms of cation stoichiometry.

Mechanical recycling processes aim to separate particles based on their physical properties, such as size, shape and density, and physico-chemical surface properties, such as wettability. Secondary materials, including electronic waste, are highly complex and heterogeneous, which complicates recycling processes. In order to improve recycling efficiency, characterization of both recycling process feed materials and intermediate products is crucial. Textural characteristics of particles in waste mixtures cannot be determined by conventional characterization techniques, such as X-ray fluorescence and X-ray diffraction spectroscopy. This paper presents the application of automated mineralogy as an analytical tool, capable of describing discrete particle characteristics for monitoring and diagnosis of lithium ion battery (LIB) recycling approaches. Automated mineralogy, which is well established for the analysis of primary raw materials but has not yet been tested on battery waste, enables the acquisition of textural and chemical information, such as elemental and phase composition, morphology, association and degree of liberation. For this study, a thermo-mechanically processed black mass (<1 mm fraction) from spent LIBs was characterized with automated mineralogy. Each particle was categorized based on which LIB component it comprised: Al foil, Cu foil, graphite, lithium metal oxides and alloys from casing. A more selective liberation of the anode components was achieved by thermo-mechanical treatment, in comparison to the cathode components. Therefore, automated mineralogy can provide vital information for understanding the properties of black mass particles, which determine the success of mechanical recycling processes. The introduced methodology is not limited to the presented case study and is applicable for the optimization of differentseparation unit operations in recycling of waste electronics and batteries.

Hexavalent uranium is of considerable importance in the actinide field, and its characterization, consequently, of fundamental concern. The application of High-Energy-Resolution Fluorescence-Detected X-ray Absorption Near-Edge Structure (HERFD XANES) at the M4 edge of actinides is gaining great popularity, as it allows to probe the 5f electronic structure with augmented resolution compared to conventional XANES, for which M4 spectra are broad and featureless. If, from one side, the extreme sensitivity of M4 HERFD XANES to actinides’ oxidation state is well-established [1], its sensitivity to the local environment has been less extensively explored [2,3]. The partially filled 5f subshell makes intra-atomic electron interactions the primary force shaping the spectrum, and simulations treating multi-electronic effects can only approximately account for the local environment.
In these regards, U6+, with its empty 5f shell, is a fortunate exceptional case. Simulation approaches based on the one-electron approximation can then be applied, and the dependence on the local environment be carefully investigated. We report here the first investigation where experimental and simulated M4 HERFD XANES are obtained on a set of U6+ compounds with different local environment. The coordination of U6+ represented by the set of samples comprises an almost perfect UO6 octahedral bipyramid (Sr3UO6), two UO6 featuring the uranyl ion (Cs2UO2Cl4 and SrUO4), and a UO8 distorted hexagonal bipyramid (CaUO4).
Experimental M4 HERFD are shown in Figure 1. The spectral shape has a similar structure, made of three or four peaks of decreasing intensity. At the same time, it presents significant differences indicating the substantial impact on the spectral shape of the local environment. We simulated the set of U6+ compounds with the DFT-based code FDMNES [4]. The good agreement between theory and experiment, see Fig. 1, makes it reasonable to have a closer look at the underlying f-density of states and to assign spectral features to specific f-orbitals.
Simulations allow to rationalize how the local coordination of U6+ affects the M4 HERFD XANES and demonstrate its high sensitivity to the local environment. Simulations based on crystal field theory were also performed. Their comparison to FDMNES results will be discussed during the conference.

To address the importance of nanoscale defects in complex magnetic oxides, we present an effective tool, variable energy positron annihilation spectroscopy, for probing the relatively small changes in anti-site disorder and oxygen vacancies of the in situ annealed double perovskite Sr₂FeMoO₆ thin films. By controlling the annealing conditions in wide pressure and temperature ranges and thus affecting the amount of nanoscale defects, we show that the magnetic properties of Sr₂FeMoO₆ thin films can be modified, particularly with the oxygen nonstoichiometry, and hence their spintronic functionality can be improved. On the basis of our findings together with proposed mechanism, we suggest that the annealing treatments can also be scaled to other complex magnetic perovskites to engineer nanoscale defects and thus improve their usability in future spintronic applications.

Density Functional Theory (DFT) is one of the most popular quantum mechanical simulation methods, since it balances sufficient accuracy with reasonable computational cost. It is often used in material science applications at ambient and extreme conditions. Nonetheless, DFT approaches its limits in terms of computational feasbility when faced with simulation problems at larger time and length scales, especially at temperatures >> 0K. Surrogate models based on neural networks can circumvent these limitations. By training a neural network to predict properties of interest (total energy, atomic forces) based on atomic configurations, predictions with DFT-like accuracy can be done at a fraction of the computational cost.
To facilitate the creation and usage of these surrogate models, the Materials Learning Algorithms package (MALA) provides modular open-source toolbox that allows users to preprocess of DFT data, train models and postprocess model predictions using only a few lines of code. MALA is jointly developed by the Center for Advanced Systems Understanding (CASUS), Sandia National Laboratories (SNL) and Oak Ridge National Laboratory (ORNL).

i-TED is an innovative detection system which exploits Compton imaging techniques to achieve a superior signal-to-background ratio in (n, γ ) cross-section measurements using time-of-flight technique. This work presents the first experimental validation of the i-TED apparatus for highresolution time-of-flight experiments and demonstrates for the first time the concept proposed for background rejection. To this aim, the 197 Au(n, γ ) and 56 Fe(n, γ ) reactions were studied at CERN n_TOF using an i-TED demonstrator based on three position-sensitive detectors. Two C6 D6 detectors were also used to benchmark the performance of i-TED. The i-TED prototype built for this study shows a factor of ∼3 higher detection sensitivity than state-of-the-art C6 D6 detectors in the 10 keV neutron-energy region of astrophysical interest. This paper explores also the perspectives of further enhancement in performance attainable with the final i-TED array consisting of twenty position-sensitive detectors and new analysis methodologies based on Machine-Learning techniques.

An accurate measurement of the 140Ce(n,g) energy-dependent cross-section was performed
at the n_TOF facility at CERN. This cross-section is of great importance because it represents a
bottleneck for the s-process nucleosynthesis and determines to a large extent the cerium abundance in
stars. The measurement was motivated by the significant difference between the cerium abundance
measured in globular clusters and the value predicted by theoretical stellar models. This discrepancy
can be ascribed to an overestimation of the 140Ce capture cross-section due to a lack of accurate
nuclear data. For this measurement, we used a sample of cerium oxide enriched in 140Ce to 99.4%.
The experimental apparatus consisted of four deuterated benzene liquid scintillator detectors, which
allowed us to overcome the difficulties present in the previous measurements, thanks to their very
low neutron sensitivity. The accurate analysis of the p-wave resonances and the calculation of their
average parameters are fundamental to improve the evaluation of the 140Ce Maxwellian-averaged
cross-section.

Mechanically controllable break junctions (MCBJs) are devices, in which the electrical properties of single molecules can be investigated with extreme precision using atomically structured metallic electrodes. The current-voltage (IV) characteristics in such junctions are considerably affected by the binding positions of the anchoring groups on the tip-facets and the configuration of the molecule. Hence, characterizing the electronic transport properties during a single tip-tip opening provides interesting insights in to the tip-molecule interaction.
In this contribution/poster, we present a novel, high-throughput approach to reproduce the time evolution of the electronic transport characteristics. For this, we performed transport calculations using the self-consistent charge scheme of the density-functional-based tight binding (SCC-DFTB)[1] approach and the Green’s function formalism. In particular, we evaluated the energy level E0 and the coupling Γ of the dominating transport channel using the single level model[2]. In contrast to standard approaches, we consider not just one molecule orientation but many thermodynamically relevant configurations. The obtained parameters were averaged using statistical weights obtained from Metropolis simulation considering up to 80.000 different configurations for selected tip-tip distances. The dependence of the averaged quantities with respect to the tip-tip separation reveals characteristic features also observed in experiments for similar molecular systems.
Our approach allows us to relate these features to binding-site and molecule-curvature effects and therefore provides a better interpretation of the experimental results.

1. M. Elstner, D. Porezag, G. Jungnickel, J. Elsner, M. Haugk, T. Frauenheim, S. Suhai, and G. Seifert, Self-consistent-charge density-functional tight-binding method for simulations of complex materials properties, Phys. Rev. B 58, 7260 (1998)
2. Cuevas, J. C.; Scheer, E. In Molecular Electronics: An Introduction to Theory and Experiment; Reed, M., Ed.; World Scientific Series in Nanoscience and Nanotechnology, Vol. 1; World Scientific: Singapore,Hackensack, NJ, 201

Using two different types of impedance biochips (PS5 and BS5) with ring top electrodes, a distinct change of measured impedance has been detected after adding 1–5 μL (with dead or live Gram‐positive Lysinibacillus sphaericus JG‐A12 cells to 20 μL DI water inside the ring top electrode. We relate observed change of measured impedance to change of membrane potential of L. sphaericus JG‐A12 cells. In contrast to impedance measurements, optical density (OD) measurements cannot be used to distinguish between dead and live cells. Dead L. sphaericus JG‐A12 cells have been obtained by adding 0.02 mg/mL of the antibiotics tetracycline and 0.1 mg/mL chloramphenicol to a batch with OD0.5 and by incubation for 24 h, 30 °C, 120 rpm in the dark. For impedance measurements, we have used batches with a cell density of 25.5 × 10⁸ cells/mL (OD8.5) and 270.0 × 10⁸ cells/mL (OD90.0). The impedance biochip PS5 can be used to detect the more resistive and less capacitive live L. sphaericus JG‐A12 cells. Also, the impedance biochip BS5 can be used to detect the less resistive and more capacitive dead L. sphaericus JG‐A12 cells. An outlook on the application of the impedance biochips for high‐throughput drug screening, e.g., against multi‐drug‐resistant Gram‐positive bacteria, is given.

Oxide-dispersion strengthened steels are promising materials for extreme service conditions including nuclear reactors core. In service conditions, nuclear fuel claddings are exposed to the fission gas pressure at temperatures about 700°C. This paper presents novel results on ODS creep properties from a round robin of inner gas pressure creep test. A gas pressure creep test, simulating fission gas loading, was designed and achieved by four different European teams. Lifetime and specific behavior of ODS steel tube are prospected. Based on a mechanical clamping achieving gas tightness, short length tubes samples are tested by different laboratories. In situ laser measurements exhibit the radial expansion of ODS steel tubes before failure. Post-mortem, geometrical characterizations are performed to determine hoop strains at failure. A consistent creep lifetime is observed by all the teams even with slightly different testing apparatus and clamping systems. Under inner gas pressure, ODS steels exhibit a typical failure by leakage associated to a very small radial expansion. This behavior results from a brutal failure (burst) without evidence of tertiary creep stage. This failure mode of ODS cladding in creep conditions is consistently observed on all samples of the study. Inner gas pressure creep tests were compared, for the first time, by four European laboratories on ODS steel tube. This technique, simulating the fission gas pressure loading, is applied on small and mechanically clamped samples. This technique shows a remarkable consistency between the different laboratories results and demonstrates to be efficient for ODS steel cladding tube qualification. The results show a correlation between the creep properties and the microstructure.

In this presentation I review our activities on flexible, printable and stretchable functional elements for human-machine interfaces, interactive electronics, soft robotics and cancer research.

Clinical treatment with protons relies on the concept of relative biological effectiveness (RBE) to convert the absorbed dose into an RBE-weighted dose that equals the dose for radiotherapy with photons causing the same biological effect. Currently, in proton therapy a constant RBE of 1.1 is generically used. However, empirical data indicate that the RBE is not constant, but increases at the distal edge of the proton beam. This increase in RBE is of concern, as the clinical impact is still unresolved, and clinical studies demonstrating a clinical effect of an increased RBE are emerging.
Within the European Particle Therapy Network (EPTN) work package 6 on radiobiology and RBE, a workshop was held in February 2020 in Manchester with one day of discussion dedicated to the impact of proton RBE in a clinical context. Current data on RBE effects, patient outcome and modelling from experimental as well as clinical studies were presented and discussed. Furthermore, representatives from European clinical proton therapy centres, who were involved in patient treatment, laid out their current clinical practice on how to consider the risk of a variable RBE in their centres. In line with the workshop, this work considers the actual impact of RBE issues on patient care in proton therapy by reviewing preclinical data on the relation between linear energy transfer (LET) and RBE, current clinical data sets on RBE effects in patients, and applied clinical strategies to manage RBE uncertainties. A better understanding of the variability in RBE would allow development of proton treatments which are safer and more effective.

Recently, a disruptive idea was reported about the discovery of a new type of battery named Liquid Displacement Battery (LDB) comprising liquid metal electrodes and molten salt electrolyte. This cell featured a novel concept of a porous electronically conductive faradaic membrane instead of the traditional ion-selective ceramic membrane. LDBs are attractive for stationary storage applications but need mitigation against self-discharge. In the instant battery chemistry, Li|LiCl-PbCl2|Pb, reducing the diffusion coefficient of lead ions can be a way forward and a solution can be the addition of PbO to the electrolyte. The latter acts as a supplementary barrier and complements the function of the faradaic membrane. The remedial actions improved the cell’s coulombic efficiency from 92% to 97% without affecting the voltage efficiency. In addition, the limiting current density of a 500 mAh cell increased from 575 to 831 mA/cm² and the limiting power from 2.53 to 3.66 W. Finally, the effect of PbO on the impedance and polarization of the cell was also studied.

In stars, the fusion of 22Ne and 4He may produce either 25Mg, with the emission of a neutron, or 26Mg and a γ ray. At high temperature, the (α,n) channel dominates, while at low temperature, it is energetically hampered. The rate of its competitor, the 22Ne(α,γ)26Mg reaction, and, hence, the minimum temperature for the (α,n) dominance, are controlled by many nuclear resonances. The strengths of these resonances have hitherto been studied only indirectly. The present work aims to directly measure the total strength of the resonance at E_{r}=334keV (corresponding to E_{x}=10949keV in 26Mg). The data reported here have been obtained using high intensity 4He+ beam from the INFN LUNA 400 kV underground accelerator, a windowless, recirculating, 99.9% isotopically enriched 22Ne gas target, and a 4π bismuth germanate summing γ-ray detector. The ultra-low background rate of less than 0.5 counts/day was determined using 67 days of no-beam data and 7 days of 4He+ beam on an inert argon target. The new high-sensitivity setup allowed to determine the first direct upper limit of 4.0×10−11 eV (at 90% confidence level) for the resonance strength. Finally, the sensitivity of this setup paves the way to study further 22Ne(α,γ)26Mg resonances at higher energy.

Nachhaltiges Bauen ist immer noch eine Nische im Baubereich, obwohl es zahlreiche Vorteile bietet. Mittlerweile wünscht sich auch die Präsidentin der EU-Kommission zur Umsetzung des „Green Deals“ einen Aufbruch auch im Baubereich, der als „New European Bauhaus“ bezeichnet wird in Anlehnung an die Ideen des Bauhauses im 20. Jahrhundert. Auch der Bund Deutscher Architekten (BDA) fordert in seinem Manifest zum klimagerechten Bauen aus dem Jahr 2020 eine Abkehr vom konventionellen Bauen und schlägt eine Reihe von Maßnahmen zu dessen Umsetzung vor, so u. a. „Achtung des Bestands“, „einfach intelligent“ oder „vollständige Entkarbonisierung“.
Beim nachhaltigen Bauen geht es u. a. darum, den gesamten genutzten Wohnraum zu reduzieren, möglichst natürliche und regionale Baustoffe mit geringem Energieinhalt zu nutzen, eine zukunftsfähige Medienversorgung einzusetzen und klimaangepasst zu bauen, also den Bedingungen, die das Klima vorgibt, mit architektonischen statt ingenieurtechnischen Lösungen zu begegnen. Eine Möglichkeit, auf diese Anforderungen einzugehen, besteht im traditionellen Bauen und der Übertragung auf zukunftsfähiges Bauen. Traditionelles Bauen kann als ein Vorbild dienen, um nachhaltig und klimagerecht zu bauen. In früheren Zeiten wurde so gebaut, wie es die regionalen Baustoffe hergaben und die klimatischen Verhältnisse erforderten. Einerseits können in den tropischen Klimazonen Häuser errichtet werden, die den lokal vorhandenen Gegebenheiten gerecht werden und den Menschen trotz der oftmals großen Hitze einigermaßen angenehme Wohnverhältnisse ermöglichen. Andererseits können in den arktischen Gebieten Menschen durch die geschickte Ausnutzung von Bauprinzipien bei eisigen Temperaturen für akzeptable Wärme in den eigenen Wänden zu sorgen. Dabei kann gerade Holz als sehr variabler und in vielfältigen Bereichen einsetzbarer Baustoff dienen, der mittlerweile auch in den Bauordnungen der Länder stärker anerkannt wird. Holz ist zudem noch eine Kohlenstoffsenke und hat insbesondere im Gegensatz zu sehr CO2-intensiven Bauprodukten auf Zementbasis wie Beton große Vorteile bezüglich der Klimarelevanz. In Verbindung mit dem ebenfalls traditionellen Baumaterial Lehm können regionale Rohstoffe genutzt werden, die sich darüber hinaus gut ergänzen und nicht zuletzt auch hohen ästhetischen Ansprüchen genügen.
In der Praxis setzt die Umsetzung nachhaltiger Bauprinzipien oftmals den Willen der Bauherren ebenso voraus wie die Erfahrungen der Bauplanerin/des Bauplaners mit nachhaltigem Bauen. Wenn beides gegeben ist, wie bei der Sanierung einer Doppelhaushälfte in einer Siedlung in Dresden-Reick, kann Wohnraum entstehen, der sowohl aus architektonischer als auch ökologischer Sicht überzeugend ist. Im Verlauf des Bauprozesses mussten teilweise auch die Handwerker überzeugt werden, da die bauseitigen Lösungen beim Einsatz ökologischer Materialien und Bauprinzipien nicht immer mit der konventionellen Herangehensweise zu erzielen sind. Durch entsprechende intensive Absprachen mit den betreffenden Handwerkern konnte aber immer eine überzeugende Lösung erreicht werden und dadurch konnten zudem beide Seiten voneinander lernen.

Die Bergbauindustrie verursacht beim Abbau von Rohstoffen große Umweltauswirkungen. Allerdings sind moderne Industriegesellschaften ohne die Gewinnung von Rohstoffen nicht denkbar. Hochtechnologie und insbesondere auch Umwelttechnologien benötigen in der Herstellung in nicht unerheblichem Maße Metalle und Minerale wie Kupfer, Indium, Lithium, Gallium, Germanium aber auch Seltene Erden und viele weitere Elemente. Die Hinterlassenschaften des Bergbaus in Form von Halden, die fortwährend bei der Rohstoffgewinnung entstehen, sorgen aber für extreme Umweltbelastungen und enthalten zudem noch immer zahlreiche Wertminerale in oft recht hohen Konzentrationen. Diese können durch verschiedene physikalische, chemische und/oder biotechnologische Aufbereitungsverfahren rückgewonnen werden. Solche Technologien sind aus den folgenden Gründen als nachhaltig zu bezeichnen.
Durch die (erneute) Aufbereitung des Haldenmaterials, bei der eine bessere Ressourcennutzung erzielt wird, lässt sich die Ressourceneffizienz erhöhen. Insbesondere Halden, die vor längerer Zeit entstanden sind, enthalten noch beträchtliche Konzentrationen an wertvollen Stoffen mit wirtschaftlicher Bedeutung. Diese aus den Halden zu gewinnen bedeutet damit, dass insgesamt weniger primärer Rohstoffe aus dem Boden gewonnen werden müssen.
Neben der Rohstoffgewinnung hat die Behandlung des Haldenmaterials auch noch zum Ziel, die potenziellen Schadstoffemissionen und anderen Umweltwirkungen zu vermindern. Teilweise kommen dabei die gleichen Verfahren zum Zuge wie bei der Gewinnung der Wertminerale. Die Sanierung solcher Bergbauhinterlassenschaften ist in vielen Fällen gesetzlich vorgeschrieben und zudem sind in den vergangenen Jahrzehnten weltweit zahlreiche katastrophale Unfälle mit Halden vorgefallen, so dass eine Haldensanierung in vielen Fällen sowieso betrieben werden muss.
Aus wirtschaftlicher Sicht ist dabei aber zu beachten, dass die Rohstoffgewinnung in aller Regel nur als eine zusätzliche Einnahmequelle dienen kann, um einen Teil der Kosten für die Haldensanierung zu decken. Theoretische Annahmen zeigen regelmäßig, dass die in den Haldenvolumina enthaltenen Wertstoffkonzentrationen zwar durchaus relevante Größenordnungen erreichen, diese aber bei genauerer Betrachtung insbesondere der Gegenrechnung der Kosten für die erforderlichen Verfahrensschritte standhalten müssen, so dass in vielen Fällen letztendlich – wenn überhaupt – ein Nullsummenspiel gegeben ist.
Am Helmholtz-Institut Freiberg wurde und wird in zahlreichen Projekten an entsprechenden Verfahren geforscht. Darüber hinaus koordiniert das HIF ein großes regionales Netzwerk (recomine), das sich den Bergbaualtlasten an der Schnittstelle von Umwelttechnologie, Ressourcentechnologie und Digitalisierung widmet und unter dessen Schirm Lösungen entwickelt werden, die regional getestet und weiterentwickelt, letztlich auf dem Weltmarkt angeboten werden sollen.

Spin waves (SWs) in magnetic nanotubes have shown interesting nonreciprocal properties in their dispersion relation, group velocity, frequency linewidth, and attenuation lengths. The reported chiral effects are similar to those induced by the Dzyaloshinskii–Moriya interaction but originating from the dipole–dipole interaction. Here, we show that the isotropic-exchange interaction can also induce chiral effects in the SW transport; the so-called Berry phase of SWs. We demonstrate that with the application of magnetic fields, the nonreciprocity of the different SW modes can be tuned between the fully dipolar governed and the fully exchange governed cases, as they are directly related to the underlying equilibrium state. In the helical state, due to the combined action of the two effects, every single sign combination of the azimuthal and axial wave vectors leads to different dispersions, allowing for a very sophisticated tuning of the SW transport. A disentangle- ment of the dipole–dipole and exchange contributions so far was not reported for the SW transport in nanotubes. Furthermore, we propose a device based on coplanar waveguides that would allow to selectively measure the exchange or dipole induced SW nonreciprocities. In the context of magnonic applications, our results might encourage further developments in the emerging field of 3D magnonic devices using curved magnetic membranes.

Coacervation can yield membranes with different permeabilities, making it attractive for technological applications in encapsulation or separation processes. During coacervation, oppositely charged species like polymers and surfactants form complexes due to coulombic attraction. These polymer-surfactant complexes are insoluble in the aqueous phase leading to phase separation. As a result, a structured membrane can form in the contact zone between a polymer and a surfactant solution. However, the details of the structure formation processes are only poorly understood.
In this study, we use a combination of the anionic biopolymer xanthan gum and cationic CnTAB surfactants. The quasi 2D-geometry of the Hele-Shaw cell allows us to observe the membrane formation and the growth dynamics in-situ. By this, we can link the membrane properties for different surfactant types and concentrations to the underlying mass transfer and structure formation processes.
The results show that the density and permeability of the formed membrane significantly depend on surfactant chain length and concentration. In a wide range of experiments, the formation of a porous structure is observed whose characteristics depend on the process parameters. The pore formation can be explained as instability of the growing membrane surface in interaction with the supply of polymer across the depleted zone in the vicinity of the membrane front. Our insights provide the basis to control membrane thickness, density, porosity and pore structure. These properties are essential for technological applications since they determine the selectivity, permeability and mechanical stability of the membrane.

For better tumor control, high-precision proton beam radiation therapy is currently being intensively discussed relative to conventional photon therapy. Here, we assumed that radiation type-specific molecular response profiles in more physiological 3D, matrix-based head and neck squamous cell carcinoma (HNSCC) cell cultures can be identified and therapeutically exploited. While proton irradiation revealed superimposable clonogenic survival and residual DNA double strand breaks (DSB) relative to photon irradiation, kinome profiles showed quantitative differences between both irradiation types. Pharmacological inhibition of a subset of radiation-induced kinases, predominantly belonging to the mitogen-activated protein kinase (MAPK) family, failed to sensitize HNSCC cells to either proton or photon irradiation. Likewise, inhibitors for ATM, DNA-PK and PARP did not discriminate between proton and photon irradiation but generally elicited a radio-sensitization. Conclusively, our results suggest marginal cell line-specific differences in the radio-sensitivity and DSB repair without a superiority of one radiation type over the other in 3D grown HNSCC cell cultures. Importantly, radiation-induced activity changes of cytoplasmic kinases induced during the first, acute phase of the cellular radiation response could neither be exploited for sensitization of HNSCC cells to photon nor proton irradiation.

An introduction to Automatic Differentiation with theory and code examples.

Y-stabilized zirconia (YSZ) is one of the reference materials for immobilization of actinide elements for long-term and secure storage of radioactive waste. YSZ adapts different structural modifications, namely monoclinic, tetragonal (unstable) and cubic. Changes in relative Y content and synthesis temperature can be used to obtained specific structural form. However, for an intermediate Y content of ~5-17 at. % a mixture of cubic and unstable tetragonal modifications can form thus compromising corresponding long-term structural integrity. Nevertheless, for this Y concentration range a stabilized tetragonal (t′) phase can be obtained through a rapid quenching of the parent cubic modification. In this work we report studies of solubility of Th in 14%Y- stabilized (t′) zirconia phase.
Series of 14%Y-ZrO2 compounds with Th at. % content of 3, 6, 9 and 12 were synthesized by sol-gel method using salts of Zr(IV), Y(III) and Th(IV) as starting materials with a final sintering temperature of 1400 K. Subsequent powder X-ray diffraction measurements were performed in order to study underlying phase and structural evolutions. It was found that the cell parameters increase nearly linearly for the Th content from 3 to 9% and no cell increase is observed for the end-member with 12%Th. Additionally, ThO2 was found to precipitate in this sample. This may indicate that Th solubility limit in the 14%Y-ZrO2 system lies within the 9-12% range. Interestingly, Th content was reported to exceed 15% for the 25%Y-ZrO2 system, as concluded from electron microscopy data. This sample, however, was found to be 25%Y-ZrO2–ThO2 phase separated. Considering that in the current study traces of ThO2 have been found already in the 9%Th sample, conditions of thermal treatment with the resulting phase equilibria may impact the Th solubility. Further details on structural and phase properties in the Th-14%Y-ZrO2 system will be presented.

Natural organic matter, such as humic and fulvic acids play a major role in the mobility of contaminants in the environment including radionuclides and nanoparticles formed by them. Humic and fulvic acids may act as stabilizers, i.e. natural surfactants, for colloids, thereby increasing their stability and mobility in the Geo- and Biosphere. This stabilization of colloidal matter is caused by three basic mechanisms: (1) electrostatic stabilization, (2) electrosteric stabilization and (3) steric stabilization. These mechanisms can contribute to different degrees to the stabilization of particulate contaminants by natural organic matter in colloidal dispersion and also influence their interactions with mineral surfaces. In order to understand the different contributions controlled homoaggregation studies on monodisperse nanoparticles have been performed using model stabilizers, such as ionic surfactants and polymers. These model scenarios allowed us to isolate electrostatic and steric components in aggregation studies using dynamic light scattering. By comparing these results to systems with different humic and fulvic acids we can elucidate which components control the stabilization of colloidal contaminants by natural organic matter.

Background: Microorganisms in deep terrestrial subsurface harbor unique metabolic traits due to insufficient sunlight, oxygen and organic carbons. Previous studies reported that in the porewaters from boreholes of Opalinus clay rocks under a deep geological repository (DGR), autotrophoic H2-oxidizing sulfate-reducing bacteria (SRB)—Peptococcaceae, Desulfatialea and Desulfobulbaceae—together with other heterotrophic and fermentative bacteria were able to alleviate the H2 pressure accumulated from the process during anoxic corrosion of steel containers for nuclear wastes. Objective and Method: What remains elusive is whether these microorganisms are porewater- or rock-origin. Thus, we re-analyzed the above-mentioned porewater communities based on the amplicon sequence variant (ASV) instead of operational taxonomic unit clustering. In addition, two cores of Opalinus rocks were collected in November of 2019. The extracted DNA/RNA from these rock samples will be subjected to 16S amplicon sequencing, metagenome and metatransctriptome to investigate microbial diversity and metabolisms; microbial colonization will also be examined via scanning electron microscopy. Result: Our principal coordinates analysis indicated that the community structure of original porewaters between different boreholes were significantly distinct in the same DGR site. Moreover, the chao1 diversity index suggested that some rare biosphere may thrive in the H2-spiked communities. The differential analysis further showed that up to 213 ASVs were significantly enriched in the H2-injected porewater communities, mainly belonging to Proteobacteria, Firmicutes, Desulfobacterota, and Bacteroidota. This ASV-resolute analysis indicated that bacteria involved in this microbial loop is more complex than previously appreciated. Besides, the preliminary results showed the DNA content of newly collected Opalinus rocks was extremely low based on Qubit quantification (0.57 ± 0.07 to 0.61 ± 0.04 ng/g of clay), whereas the total RNA was not quantifiable via Qubit. Despite this, the V4 region of 16S rRNA gene was able to be amplified, indicating the presence of microorganisms with low biomass. In future, 16S amplicon sequences from rocks will be analyzed together with porewater communities. The DNA will be applied to multiple displacement amplification prior to metagenome sequencing. The understanding of microbial ecology in deep subsurface not only benefits nuclear wastes management but also underpins the notion of evolutionary and astrobiology.

Attachment of bacteria in natural conditions enable them a sustainable development, resulting in biofilm formation. Staying within biofilms, bacteria areprotected from colonization by other microbes, and they form mutualistic communities that allow to trade off inevitable compounds. The presence of thebiofilms is also a key process in biotechnological setups since microbes are protected from abiotic conditions (e.g. temperature, flushing, product separation),which enables a long term processing without continuous replacement of biomass. However, not all bacteria tend to attach very well and form biofilms sincethey lack surface receptors, do not produce extracellular matrices or do not have other appendages (e.g. pili, flagella) that facilitate the attachment. Therefore,we propose an alternative solution by micro-structuring the surface with different sizes of holes, which would enable cells to attach. Accordingly, we aimed todetermine interplay between (i) topography, (ii) fluid flow as well as salt concentration and (iii) the cell geometry and cell wall structure to the process ofattachmentt of cells. Our results showed that the structured surfaces with the depth, close to the size of bacteria are the most suitable to induce cellularattachment. We observed that specific features as biofilm formation or cell wall structure significantly differentiate the cells in the ability to colonize the surface.Since we tested attachment under flow conditions, the amount of deposited cells was dependent on the particular conditions of flow, while salinity of mediasignificantly improved the attachment.

Tetravalent actinides form colloids at near neutral pH in the presence of silicic acid. This may have significant impact on actinide mobility in the far field of a nuclear waste repository or the case of accidental release of actinides into the environment as silicate is ubiquitous in natural waters and is of special importance in the case of nuclear waste repositories in crystalline rock formations. We investigated the formation, stability and mobility of such colloids employing the tetravalent actinide analog zirconium and the radiotracer Zr-89. The radiotracer was produced at the in-house IBA Cyclone 18/9 cyclotron at the HZDR Research Site Leipzig. A foil of metallic yttrium was irradiated with 14.5 MeV protons to trigger the nuclear reaction Y-89(p,n)Zr-89. The target was subsequently dissolved and the radiotracer was isolated via ion chromatography methods using UTEVA resin.
The radiotracer was employed to synthesize zirconium oxyhydroxy silicate colloids that form spontaneously at near neutral pH at Si concentrations between 0.5 – 2 mM. In contrast to the Zr(O)(OH)2 particles that precipitate without silicates these colloids remain in stable dispersion. Column experiments in model porous media reveal a potentially massively increased mobility of these colloids due to very low affinities for the geomatrix surface.
The stability of these colloids was further investigated by producing particles from solutions containing various Zr : Si ratios. Homoaggregation affinity measurements on these systems by dynamic light scattering reveal an increasing stabilization of the colloids with increasing silica content hinting at (electro-)steric stabilization mechanisms due to polymeric silicic acid structures at the colloid surface. Consequently an increased mobility of low concentration tetravalent actinides through colloid formation may occur in environments with silicic acid presence.

In nuclear power plants and other nuclear facilities the removal of cobalt from radioactive liquid waste is needed to reduce the radioactivity concentration in effluents. In liquid wastes containing strong organic complexing agents such as EDTA cobalt removal can be problematic due to the high stability of the Co-EDTA complex. In this study, the removal of cobalt from NaNO3 solutions using antimony oxide (Sb2O3) synthesized from potassium hexahydroxoantimonate was investigated in the absence and presence of EDTA. The uptake studies on the ion exchange material were conducted both in the dark (absence of UV-light) and under UV-C irradiation. Ca2+ or Ni2+ were included in the experiments as competing cations to test the selectivity of the ion exchanger. Results show that UV-C irradiation noticeably enhances the cobalt sorption efficiency on the antimony oxide. It was shown that nickel decreased the sorption of cobalt to a higher extent than calcium. Finally, the sorption data collected for Co2+ on antimony oxide was modeled using six different isotherm models. The Sips model was found to be the most suitable model to describe the sorption process. The Dubinin-Radushkevich model was further used to calculate the adsorption energy, which was found to be 6.2 kJ mol-1.

Y-stabilized zirconia (YSZ) is one of the reference materials for immobilization of actinide elements for long-term and secure storage of radioactive waste. YSZ adapts different structural modifications, namely monoclinic, tetragonal (unstable) and cubic [1]. Changes in relative Y content and synthesis temperature can be used to obtain specific structural form. However, for an intermediate Y content of ~5-17 at.% a mixture of cubic and unstable tetragonal modifications can form thus compromising corresponding long-term structural integrity. Nevertheless, for this Y concentration range a stabilized tetragonal (t′) phase can be obtained through a rapid quenching of the parent cubic modification. Addition of Th was shown to influence phase composition and stability in the YSZ system as well [2]. In this work we report studies of solubility of Th in 14%Y- stabilized zirconia phase.
Series of 14%Y-ZrO2 compounds with Th at. % content of 3, 6, 9 and 12 were synthesized by sol-gel method from salts of Zr(IV), Y(III) and Th(IV). Subsequent powder synchrotron radiation diffraction measurements were performed in order to study underlying phase and structural evolutions. It was found that the cell parameters increase nearly linearly for the Th content from 3 to 9% and no cell increase is observed for the end-member with 12%Th. Additionally, ThO2 was found to precipitate in this sample. This may indicate that Th solubility limit in the 14%Y-ZrO2 system situates near 9%. Interestingly, Th content was reported to exceed 15% for the 25%Y-ZrO2 system, as concluded from electron microscopy data [3]. Studied samples, however, were found to be 25%Y-ZrO2–ThO2 phase separated. Considering that in the current study traces of ThO2 have been found already in the 9%Th sample, conditions of thermal treatment with the resulting phase equilibria may impact Th solubility. Further details on structural and phase properties in the Th-14%Y-ZrO2 system will be presented.

[1] Scott H G 1975 J. Mater. Sci. 10 1527–35
[2] Zhao M, Ren X, Yang J and Pan W 2016 Ceram. Int. 42 501–8
[3] Grover V, Sengupta P and Tyagi A K 2007 Mater. Sci. Eng. B 138 246–50

The Institute of Resource Ecology / HZDR is operating the Rossendorf Beamline (ROBL/BM20) at the ESRF for over 20 years. A second experimental hutch with two diffractometers for single crystal, powder and surface diffraction has been constructed in the last two years. As CRG beamline provides ROBL 1/3 of its beam time via the ESRF proposal system to the user community, whereas 2/3 are reserved for in-house research.
One diffractometer is a 6-circle Huber diffractometer with Eulerian cradle geometry (XRD-1). It will be used for high-resolution powder diffraction and surface diffraction. Powder diffraction measurements will be performed with a Pilatus 100k Si or an Eiger CdTe 500k detector mounted on the detector arm. The Bragg reflexes are extracted by radial integration using a modified pyFAI code.
The diffractometer for single crystal diffraction and in situ diffraction measurements (XRD-2) is equipped with a Pilatus3 X 2M detector. Diffraction measurements can be combined simultaneously with XANES and XRF spectroscopy. The setup comprises a cryo stream cooler (80-400 K) and a heater (up to 1200 K). The diffractometer is controlled with the Pylatus software and the single crystal data extraction is performed with CrysAlisPro.
We will report the first experiments performed on the two diffractometers.

Quantitative nanoscale imaging using transmission He ion channelling contrast: Proof-of-concept and application to study isolated crystalline defects

Reliable performance of passive safety systems – which function using natural physics laws such as density difference without external interventions during an accident- is an important issue with respect to nuclear power plant (NPP) safety. Investigation of thermal behavior and the operational stability of passive safety systems in Generation III and III+ nuclear reactors is the objective of the German project PANAS (PAssive Nachzerfallswärme-AbfuhrSysteme – Passive Residual Heat Removal System) funded by the German Federal Ministry of Education and Research (BMBF). In this context, experiments are being performed in the high-pressure COSMEA test facility at HZDR (Helmholtz Zentrum Dresden Rossendorf) to assess the emergency condenser (EC) based on the KERENA boiling water reactor. The objective of the presented work is to complement previous efforts related to the primary side heat transfer coefficient with the focus on heat transfer assessment of the secondary side. The assessment of state-of-the-art heat transfer models has been presented, and it shows that they often fail to predict the heat transfer behavior of the secondary side in COSMEA test facility. Therefore, because of the system’s sensitive heat transfer behavior due to different factors such as mass flow rate, it is important to have an accurate determination of heat transfer performance in the system. In this regard, a 3D CFD simulation of the COSMEA secondary side by ANSYS CFX has been proposed to show the flow pattern, temperature gradient and heat transfer performance of the system. The COSMEA experiments serve as validation basis for the CFD simulation.

Der Großteil elektrischer Energieerzeugung erfolgt durch thermische Kraftkreisläufe, welche durch eine Wärmequelle versorgt werden. Hierbei werden zwei Typen kommerzieller Anlagen betrieben, der offene direkt befeuerte Brayton oder Joule-Kreislauf (bsp. Gasturbinenkreisläufe) und der geschlossene indirekt befeuerte Rankine-Kreislauf (Dampfkreislauf). Neben diesen konventionellen Kraftkreisläufen existiert seit einigen Jahren, basierend auf den Brayton-Kreislauf, ein innovatives Konzept mit superkritischen Kohlenstoffdioxid (sCO2) als Arbeitsmedium. Zahlreiche Studien haben gezeigt, dass sCO2 Kreisläufe das Potential haben, höhere Wirkungsgrade zu erreichen, einen niedrigeren Brennstoff- und Wasserverbrauch zu erzielen (Subbaraman et al., 2011; Kacludis et al., 2012; Shelton et al., 2016). SCO2 kombiniert den Vorteil der hohen Dichte von Flüssigkeiten und die niedrige Viskosität von Gasen, sodass geringere Komponentengrößen, kleinere Footprints der Gesamtanlage und damit niedrigere Kapitalkosten möglich sind.
Bei der Prozessführung wird zwischen dem offenen und dem geschlossenen sCO2 Brayton-Kreislauf unterschieden. Bei einem geschlossenen Kreislauf wird sCO2 nahe des kritischen Punktes (ca. 31 °C und 74 bar) verdichtet, in einem Rekuperator vorgewärmt, in einem Erhitzer durch die Wärmequelle aufgeheizt, in einer Expansionsturbine entspannt, durch den Rekuperator auf der Gegenseite geführt und anschließend bis nahe des kritischen Punktes zurückgekühlt, um den Kreislauf erneut zu beginnen. Dieser Prozess kann für unterschiedlichste Wärmequellen, wie fossile Kraftstoffe, Kernenergie, industrielle Abwärme, Geothermie oder Solarstrahlung eingesetzt werden. Der offene Kreislauf adressiert dagegen höhere Temperaturen und wird üblicherweise für eine Sauerstoffverbrennung untersucht. Dabei wird ein Sauerstoff-Methan-Gemisch bei hohen Druck und hoher Temperatur verbrannt. Das Rauchgas wird dann, vermischt mit großen Mengen sCO2, in einer Turbine entspannt. Das sCO2-Wasserdampf-Gemisch wird ebenfalls in einem Rekuperator genutzt, um anschließend Wasser sowie kleine Mengen CO2 mittels Kondensation sowie Abtrennung aus dem Kreislauf zu entfernen. Der verbleibende sCO2-Strom wird erneut dem Verbrennungsprozess zugeführt. Dieser offene Kreislauf ist besonders attraktiv, um Erdgas, synthetisch erzeugte Gase oder vergaste Kohle zu nutzen. Verglichen mit dem geschlossenen Kreislauf können hier noch höhere Wirkungsgrade und Leistungsdichten erreicht werden.
Um diese Kraftwerkskonzepte sowie die dafür notwendigen Komponenten auf einer experimentellen Basis untersuchen zu können, wurde das Projekt CARBOSOLA in Zusammenarbeit mit der TU Dresden, dem DLR und der Siemens Energy AG initiiert. Inhalt dieses Projektes ist unter anderem der Aufbau einer Versuchsanlage am HZDR, zur Untersuchung von sCO2 bei bis zu 650 °C, bei gleichzeitig 300 bar und einem Massenstrom bis zu 3,3 kg/s. Die damit verbundenen Herausforderungen und Lösungen werden erläutert.

In many domains of modern physics, we encounter the situation that generations of scientists have created high precision simulations of the effects under study. Today, these simulations have become essential to the scientific method. However, these
(often mechanistic) simulations of high predictive power carry with them a burden of inference. Once a forward process has been simulated, an inversion of a simulation given observed data from experiments is challenging, sometimes even impossible.

In this presentation, I'd like to provide an introduction to simulation based inference for inverting a beamline simulation at BESSY in Berlin. In this project, I studied the inversion of a beamline simulation using state-of-the-art machine learning. We will start our journey with normalizing flows, walk by conditional invertible neural networks and finish with Automatic Posterior Transformation for Likelihood-Free Inference. To stay with the metaphor: please bring your mathematical boots, wear a hat of Bayes Law and bring your best compass of statistics - otherwise you likely get lost in about a quarter of the presentation.

In the completed project DCS-MONITOR, feasibility studies for non-invasive monitoring of the container contents were carried out by the applicants using numerical and laboratory experimental tools. Radiation-based measurement techniques, thermography, acoustic spectroscopy and technical vibration analysis were investigated for their suitability. The previous analyses showed that the photon and neutron field around the vessel, muon imaging and passive acoustic spectroscopy are in principle suitable for monitoring the vessel inventory, but also differ in their informative value. For thermography, a lack of informative value was found for physical reasons. For active vibration diagnostics, technical hurdles and informative value were assessed negatively. With regard to passive acoustic spectroscopy, experts also dispute whether embrittled cladding tubes burst at all, with a corresponding sound emission in the container. On the basis of these results, the approaches of radiation field-based diagnostics with gamma radiation, neutrons and muons are investigated in more detail within the project DCS-MONITOR II in order to qualify them as an applicable monitoring procedure especially for CASTOR casks. For the first time, this includes studies on large scale geometries and containers.

Open Access, Open Research Data und Open Research Software: Diese Themen prägen die aktuellen Diskussionen zu Open Science in der Helmholtz-Gemeinschaft. Doch an welchen Indikatoren lässt sich der Kulturwandel hin zu Open Science festmachen? Und welche Anreize setzen Indikatoren für die Entwicklung von Open Access? Diesen und weiteren Fragen widmete sich das virtuelle Helmholtz Open Science Forum unter dem Motto „Indikatoren für Open Science“ am 20. Januar 2021. Im Zuge der Veranstaltung wurden anhand von Impuls- und Praxisvorträgen Indikatoren für Open Science vorgestellt, untersucht und mit einem breiten Publikum aus der Helmholtz-Gemeinschaft diskutiert. Dieser Report fasst die Vorträge und Diskussionen des Forums zusammen und bietet eine Basis für weitere Entwicklungen des Themenfeldes in der Gemeinschaft.

The ability to dynamically control chirality remains a grand challenge in chemistry. Although many molecules possess chiral isomers, lacking their isolation, for instance during photoisomerization, results in racemic mixtures with suppressed enantiospecific chiral properties. Here, we present a nanoporous solid in which chirality and enantioselective enrichment is induced by circularly polarized light (CPL). The material is based on photoswitchable fluorinated azobenzenes attached to the scaffold of a crystalline metal–organic framework (MOF). The azobenzene undergoes trans-to-cis-photoisomerization upon irradiation with green light and reverts back to trans upon violet light. While each moiety in cis conformation is chiral, we show the trans isomer also possesses a nonplanar, chiral conformation. During photoisomerization with unpolarized light, no enantiomeric enrichment is observed and both isomers, R- and S-cis as well as R- and S-trans, respectively, are formed in identical quantities. In contrast, CPL causes chiral photoresolution, resulting in an optically active material. Right-CPL selectively excites R-cis and R-trans enantiomers, producing a MOF with enriched S-enantiomers, and vice versa. The induction of optical activity is reversible and only depends on the light-handedness. As shown by first-principle DFT calculations, while both, trans and cis, are stabilized in nonplanar, chiral conformations in the MOF, the trans isomer adopts a planar, achiral form in solution, as verified experimentally. This shows that the chiral photoresolution is enabled by the linker reticulation in the MOF. Our study demonstrates the induction of chirality and optical activity in solid materials by CPL and opens new opportunities for chiral resolution and information storage with CPL.

The goal of this project is to support researchers in publishing their research software, in a way that makes it findable, comprehensible, citable and reusable. The key to this is the creation, curation and deposit of rich metadata with software publications. To this end, the project will conceptualize, produce and provide well-documented, adoption-ready workflows with automation interfaces and reference implementations for InvenioRDM and Dataverse.

The HELIPORT project aims at developing a platform which accommodates the complete life cycle of a scientific project and links all corresponding programs, systems and workflows to create a more FAIR and comprehensible project description.

We show that the lower levels of a large-spin network with a collective anti-ferromagnetic interaction and collective couplings to three reservoirs may function as a quantum absorption refrigerator. In appropriate regimes, the steady-state cooling current of this refrigerator scales quadratically with the size of the working medium, i.e., the number of spins. The same scaling is observed for the noise and the entropy production rate.

Recent years have seen tremendous progress in the theoretical understanding of quantum systems driven dissipatively by coupling them to different baths at their edges. This was possible because of the concurrent advances in the models used to represent these systems, the methods employed, and the analysis of the emerging phenomenology. Here we aim to give a comprehensive review of these three integrated research directions. We first provide an overarching view of the models of boundary driven open quantum systems, both in the weak and strong coupling regimes. This is followed by a review of state-of-the-art analytical and numerical methods, both exact, perturbative and approximate. Finally, we discuss the transport properties of some paradigmatic one-dimensional chains, with an emphasis on disordered and quasiperiodic systems, the emergence of rectification and negative differential conductance, and the role of phase transitions.

This work deals with the validation of a high-fidelity multiphysics system coupling the Serpent 2 Monte Carlo neutron transport code with SUBCHANFLOW, a subchannel thermalhydraulics code, and TRANSURANUS, a fuel-performance analysis code. The results for a full-core pin-by-pin burnup calculation for the ninth operating cycle of the Temelín II VVER-1000 plant, which starts from a fresh core, are presented and assessed using experimental data. A good agreement is found comparing the critical boron concentration and a set of pin-level neutron flux profiles against measurements. In addition, the calculated axial and radial power distributions match closely the values reported by the core monitoring system. To demonstrate the modeling capabilities of the three-code coupling, pin-level neutronic, thermalhydraulic and thermomechanic results are shown as well. These studies are encompassed in the final phase of the EU Horizon 2020 McSAFE project, during which the Serpent-SUBCHANFLOW-TRANSURANUS system was developed. © 2021

Intrinsic two-dimensional (2D) magnetic materials with room-temperature ferromagnetism and air stability are highly desirable for spintronic applications. However, the experimental observations of such 2D or ultrathin ferromagnetic materials are rarely reported owing to the scarcity of these materials in nature and for the intricacy in their synthesis. Here, we report a successful controllable growth of ultrathin γ-Fe2O3 nanoflakes with a variety of morphologies tunable by the growth temperature alone using a facile chemical vapor deposition method and demonstrate that all ultrathin nanoflakes still show intrinsic room-temperature ferromagnetism and a semiconducting nature. The γ-Fe2O3 nanoflakes epitaxially grown on α-Al2O3 substrates take a triangular shape at low temperature and develop gradually in lateral size, forming eventually a large-scale γ-Fe2O3 thin film as the growth time increases due to a thermodynamic control process. The morphology of the nanoflakes could be tuned from triangular to stellated, petaloid, and dendritic crystalloids in sequence with the rise of precursor temperature, revealing a growth process from thermodynamically to kinetically dominated control. Moreover, the petaloid and dendritic nanoflakes exhibit enhanced coercivity compared with the triangular and stellated nanoflakes, and all the nanoflakes with diverse shapes possess differing electrical conductivity. The findings of such ultrathin, air-stable, and room-temperature ferromagnetic γ-Fe2O3 nanoflakes with tunable shape and multifunctionality may offer guidance in synthesizing other non-layered magnetic materials for next-generation electronic and spintronic devices.

Uranium (U) is a naturally occurring metal; its environmental levels can be increased due to processes in the nuclear industry and fertilizer production. The transfer of U in the food chain from plants is associated with deleterious chemical and radiation effects. To date, limited information is available about U toxicity on plant physiology. This study investigates the responses of metal-accumulating plants to different concentrations of U. The plants Noccaea caerulescens and Noccaea goesingense are known as metal hyperaccumulators and therefore could serve as candidates for the phytoremediation of radioactive hotspots; Plantago major is a widely used pharmaceutical plant that pioneers polluted grounds and therefore should not contain high concentrations of toxic elements. The experimental plants were grown hydroponically at U concentrations between 1 μM and 10 mM. The content of U and essential elements was analyzed in roots and leaves by ICP-MS. The amount of accumulated U was influenced by its concentration in the hydroponics. Roots contained most of the metal, whereas less was transported up to the leaves, with the exception of N. goesingense in a medium concentration of U. U also influenced the nutrient profile of the plants. We localized the U in plant tissues using EDX in the SEM. U was evenly distributed in roots and leaves of Noccaea species, with one exception in the roots of N. goesingense, where the central cylinder contained more U than the cortex. The toxicity of U was assessed by measuring growth and photosynthetic parameters. While root biomass of N. caerulescens was not affected by U, root biomass of N. goesingense decreased significantly at high U concentrations of 0.1 and 10 mM and root biomass of P. major decreased at 10 mM U. Dry weight of leaves was decreased at different U concentrations in the three plant species; a promotive effect was observed in N. caerulescens at lowest concentration offered. Chlorophyll a fluorescence was not affected or negatively affected by U in both Noccaea species, whereas in Plantago also positive effects were observed. Our results show that the impact of U on Plantago and Noccaea relates to its external concentration and to the plant species. When growing in contaminated areas, P. major should not be used for medicinal purpose. Noccaea species and P. major could immobilize U in their rhizosphere in hotspots contaminated by U, and they could extract limited amounts of U into their leaves.

For a safety assessment of repositories, possible accident scenarios must be considered. If radionuclides (RNs) are released from a repository into the groundwater, they can migrate and interact with the biosphere. In addition to microorganisms, higher organisms such as plants also play a role in this context. For this reason, it is necessary that a process understanding on RN plant interactions on the molecular level is elucidated by suitable biochemical and spectroscopic methods to improve biogeochemical models for a reliable modeling of the transfer behavior of RNs in the environment up to the food chain. Interaction with plant cells can lead to immobilization and speciation changes of the RNs. Uranium as the main component (by mass) of spent nuclear fuel rods is of interest for our investigations. Furthermore, we studied europium as a non-radioactive analogue for the trivalent actinides Am(III) and Cm(III), whereby the former in particular will dominate the radiotoxicity in a potential repository. We investigated the time and concentration-dependent immobilization of these two metals to the biomass of different plant cell cultures. Biochemical methods were accompanied by spectroscopic (time-resolved laser-induced fluorescence spectroscopy, TRLFS) and microscopic techniques for determination of speciation and localization of the metals within the plant cells, respectively. In addition, the combination of luminescence spectroscopy with microscopy in the form of chemical microscopy revealed for the first time the spatially resolved localization of different Eu(III) species in plant root tissues. We observed bioassociation (immobilization) of U(VI)/Eu(III), but in some cases also re-mobilization of U(VI), which temporally coincided with a change in the metal speciation in solution. Moreover, we successfully identified metabolites released by the plant cells that can complex with U(VI)/Eu(III) and influence their mobility and thus bioavailability in the environment. Our studies can help to integrate RN plant interactions in assessment strategies of nuclear waste repositories.

The high-field magnetic properties and magnetic order of the gem mineral green dioptase Cu₆[Si₆O₁₈] · 6H₂O have been studied by means of single-crystal neutron diffraction in magnetic fields up to 21 T and magnetization measurements up to 30 T. In zero field, the Cu²⁺ moments in the antiferromagnetic chains are oriented along the c axis with a small off-axis tilt. For a field applied parallel to the c axis, the magnetization shows a spin-flop-like transition at B^∗ = 12.2 T at 1.5 K. Neutron diffraction experiments show a smooth behavior in the intensities of the magnetic reflections without any change in the periodicity of the magnetic structure. Bulk and microscopic observations are well described by a model of ferromagnetically coupled antiferromagnetic XXZ spin- 1/2 chains, taking into account a change of the local easy-axis direction.We demonstrate that the magnetic structure evolves smoothly from a deformed Néel state at low fields to a deformed spin-flop state in a high field via a strong crossover around B^∗. The results are generalized for different values of interchain coupling and spin anisotropy.

The report summarizes the results obtained by the Institute of Resource Ecology of the Helmholtz-Zentrum Dresden-Rossendorf within the BMWi-financed Joint Research Project “Geochemical retention of radionuclides on cement alteration phases (GRaZ)”. The project focused on the retention behavior of Ca-bentonite and cementitious material, both constituents of the geo-engineered barrier of deep geological repositories for high-level radioactive waste, towards radionuclides. Specifically, the influence of increased salinities and of hyperalkaline conditions on interaction processes in the system radionuclides – organics – clay/cementitious materials – aquifer was studied. For this purpose, complexation, sorption and desorption studies were performed at alkaline to hyperalkaline pH conditions (pH 8-13) and under variation of the ionic strength (0.1 to 4 M) applying complex solution compositions. For the U(VI) citrate system molecular structures dominating in the pH range 2-9 were studied spectroscopically (NMR, UV-Vis, FT-IR). As dominating species 2:2, 3:3, 3:2 and, above critical concentrations also 6:6 and 9:6 U(VI) citrate complexes were identified or confirmed and complex formation constants were determined. U(VI) sorption on Ca-bentonite at (hyper)alkaline conditions in mixed electrolyte solutions was studied by means of batch sorption experiments. The U(VI) retention on Ca-bentonite was shown to be very effective at pH>10, even in the presence of carbonate and despite the prevalence of anionic aqueous uranyl species. The presence of two independent U(VI) surface complexes on Ca-bentonite at pH 8-13 was shown by site-selective TRLFS and EXAFS spectroscopy. The sorption of anionic uranyl hydroxide complexes to the mineral surface was shown to be mediated by calcium cations. In further experiments, the effect of isosaccharinic acid (ISA) and polycarboxylate ether (PCE) on U(VI) and Eu(III) sorption, respectively, on Ca-bentonite was studied. An effect of ISA on U(VI) sorption on Ca-bentonite only occurs when ISA is present in very high excess to U(VI). The effect of PCE, as a commercial cement superplasticizer, on Eu(III) sorption onto Ca-bentonite was negligible already at moderate ionic strengths. The retention of U(VI) and Cm(III) by various C-(A-)S-H phases, representing different alteration stages of concrete, was studied by batch sorption experiments. Sorbed or incorporated actinide species were identified by TRLFS. The stability of U(VI) and Cm(III) doped C-(A-)S-H phases at high ionic strengths conditions was studied in solutions simulating the contact with North German claystone formation water. Potential changes of actinide speciation as well as formation of secondary phases due to leaching effects were followed spectroscopically. The results of this project show that both bentonite and cementitious material constitute an important retention barrier for actinides under hyperalkaline conditions and increased ionic strength.

Energy storage is a central element of future energy systems. In the process industry, the storage of heat is of particular importance. The talk discusses possible applications of high-temperature heat storage in thermal separation processes using the example of a new heat storage material produced from bauxite residues by the company Alferrock GmbH.

Background: Cancer research faces the problem of high rates of clinical failure of new treatment approaches after positive preclinical data. We hypothesize that a major confounding factor to this problem in radiooncology is the choice of the preclinical endpoint. Methods: We present a comprehensive re-evaluation of large-scale preclinical in-vivo data on fractionated irradiation alone or simultaneously with Epidermal Growth Factor Receptor inhibition. Taking the permanent local tumour control assay as a gold standard, we evaluated different tumour volume dependent endpoints that are widely used for preclinical experiments. Results: The analysis showed the highest correlations between volume related and local tumour control endpoints after irradiation alone. For combined treatments, wide inter-tumoural variations were observed with reduced correlation between the endpoints. Evaluation of growth delay per Gray (GD/Gy) based on two or more dose levels showed closest correlation with local tumour control dose 50% (TCD50). Conclusions: GD/Gy with at least two dose groups correlates with TCD50, but cannot replace the latter as the goldstandard.

Background: In preclinical radio-oncological research, local tumour control is considered the most relevant endpoint as it reflects the inactivation of cancer stem cells. Preclinical tumour-control assays may compare dose–response curves between different radiotherapy strategies, e.g., assessing additional targeted drugs and immunotherapeutic interventions, or between different radiation modalities. To mimic the biological heterogeneity of human tumour populations and to accommodate for approaches of personalized oncology, preclinical studies are increasingly performed combining larger panels of tumour models. For designing the study protocols and to obtain reliable results, prospective sample-size planning has to be developed that accounts for such heterogeneous cohorts. Methods: A Monte-Carlo-based method was developed to estimate the sample size of a comparative 1:1 two-arm prospective tumour-control assay. Based on repeated logistic regression analysis, pre-defined dose levels, assumptions on the dose–response curves of the included tumour models and on the dose-modifying factors (DMF), the power is calculated for a given number of animals per dose group. Results: Two applications are presented: (i) For a simple tumour-control assay with the head and neck squamous cell carcinoma (HNSCC) model FaDu, 10 animals would be required for each of 7 dose levels per arm to reveal a DMF of 1.25 with a power of 0.82 without drop out (total: 140 animals). (ii) In a more complex experiment combining six different lung tumour models to a heterogeneous population, 21 animals would be required for each of 11 dose levels per arm to reveal a DMF of 1.25 with a power of 0.81 without drop out (total: 462 animals). Analyzing the heterogeneous cohort reduces the required animal number by more than 50% compared to six individual tumour-control assays. Conclusion: An approach for estimating the required animal number for comparative tumour-control assays in a heterogeneous population is presented, allowing also the inclusion of different treatments as a personalized approach in the experimental arm. The software is publicly available and can be applied to plan comparisons of sigmoidal dose–response curves based on logistic regression.

Alumina thin films are synthesized by combustion synthesis of mixtures of aluminium nitrate (ALN) and methylcarbazate (MCZ). The interdependence of the ratio of oxidizer and reducing agent on composition, microstructure and electronic properties of the resulting oxide layers is investigated. The dielectric and insulating behaviour is improved by addition of different amounts of MCZ (MCZ : ALN = 0.67 or 2.5). In this way films (thickness ∼140 nm) with a dielectric constant κ of 9.7 and a dielectric loss tan δ below 0.015 can be achieved. Medium concentrations of MCZ (MCZ : ALN = 1.0 or 1.5) lead to films with lower performance, though. Our studies indicate two opposing effects of the organic additive. Removal of organic residues during film formation as combustion gases is potentially detrimental. Larger amounts of MCZ, however, cause condensation reactions in the precusor mixture, which improve the microstructure. The porosity of the films can be sucessfully analyzed by positron annihilation liftetime studies. In this way the impact of the organic ligand sphere on the resulting microstructure can be quantified. Samples prepared from ALN alone exhibit mesopores and also larger micropores. In contrast, the formation of mesopores can be inhibited by addition of MCZ.

Low-energy magnon excitations in magnetoelectric LiFePO₄ have been investigated by high-frequency–highfield electron spin resonance spectroscopy inmagnetic fields up to B = 58 T and frequencies up to f = 745 GHz. For magnetic fields applied along the easy magnetic axis, the excitation gap softens and vanishes at the spin-flop field of B_SF = 32 T before hardening again at higher fields. In addition, for B ≲ B_SF we observe a resonance mode assigned to excitations due to Dzyaloshinskii-Moriya (DM) interactions, thereby evidencing a sizable DM interaction of ≈150 μeV in LiFePO₄. Both the magnetization and the excitations up to high magnetic fields are described in terms of a mean-field theory model which extends recent zero-field inelastic neutron scattering results. Our results imply that magnetic interactions as well as magnetic anisotropy have a sizable quadratic field dependence which we attribute to significant magnetostriction.

Liquid metal batteries (LMBs) are a new technology for grid-scale energy storage. They consist of all liquid cells that operate
with liquid metals as electrodes and molten salts as electrolytes. The
liquids separate into three stably stratified layers by virtue of
density and mutual immiscibility (see the two upper left inserts in
Fig.~\ref{fig}a). This conceptually very simple and self-assembling
structure has the unique advantage to allow for an easy scale-up at
the cell level: single-cell cross sections can potentially reach
several square-meters. Such cell sizes enable highly favourable and
otherwise unattainable ratios of active to construction material
because of the cubic scaling (volume) of the former and the quadratic
scaling (surface) of the latter.

The talk will start with a general introduction to LMBs and then focus
on the fluid mechanics in these devices. Electric currents, magnetic fields, and heat
and mass transfer are tightly coupled with the cells'
electrochemistry. First a number of fluid dynamic instabilities will
be discussed in relation to operational safety. The remainder of the
talk will deal with transport phenomena in the positive
electrode. While transport in most modern battery systems is typically
dominated by diffusion and migration in micrometer-scale liquid layers
and solids, convection - with exception of the aforementioned
redox-flow batteries - rarely plays a role. This is in stark contrast
to LMBs were mediated by the fully liquid interior fluid flow can be
driven by various mechanisms. The influence of solutal convection on
the cycling behavior of a cell will be
demonstrated. Electromagnetically induced convection can be used to
improve mixing thereby mitigating diffusion
overpotentials.

Ultrasound is a powerful means to study numerous phenomena of condensed-matter physics as acoustic waves couple strongly to structural, magnetic, orbital, and charge degrees of freedom. In this paper, we present such a technique combined with single-turn coils (STCs) that generate magnetic fields beyond 100 T with the typical pulse duration of 6 μs. As a benchmark of this technique, the ultrasound results for MnCr₂S₄, Cu6[Si₆O₁₈]⋅6H₂O, and liquid oxygen are shown. The resolution for the relative sound-velocity change in the STC is estimated as Δv/v ∼ 10⁻³, which is sufficient to study various field-induced phase transitions and critical phenomena.

Using first-principle calculations, the magnetic properties of the monovacancies and the Sb-related defects including VZn, VO, SbZn, SbO, SbZn-VZn and SbZn-2VZn are studied. It is found that the isolated VZn with the charge state of 0 and −1 can contribute to ferromagnetism in ZnO material. The substitution of Sb on O sites (SbO0) also results in magnetic property. Moreover, the SbZn-2VZn complex is another defect having non-zero magnetic moment and energetically favors for the ferromagnetic state. The resultant density of states (DOS) and spin density distribution clearly show that the ferromagnetic interaction is majorly due to the O-p Zn-d and Sb-p states. To check this calculation, Sb-doped ZnO samples were grown by pulsed laser deposition with different Sb composition under P(O2) = 1.3 Pa. SQUID study showed that all of these samples are ferromagnetic at room temperature. The variation of the saturation magnetization against the Sb composition is discussed.

Lack of appropriate flow measurement techniques for liquid steel during continuous casting limits the application of control strategies that could improve the quality of the end product. Contactless Inductive Flow Tomography (CIFT) is a promising measurement technique that can provide information about the flow structure in the mould to a real time controller. On this basis, electromagnetic actuators can be used to react on undesired flow conditions in the mould. However, because of their nature, these actuators pose a significant challenge for inductive measurement methods. In this work we describe the influence of an electromagnetic brake on CIFT in a laboratory environment. We also show how this influence can be fully compensated, which facilitates the viability of CIFT as a key ingredient of real time control of continuous casting.

Purpose: This prospective trial investigates the association of time to recurrence (TTR) in glioblastoma with [11C]methionine (MET) tracer uptake before postoperative radiochemotherapy (RCT) aiming to guide radiotherapy boost regions.

Experimental Design: Between 2013 and 2016, 102 patients with glioblastoma were recruited. RCT was performed with concurrent and adjuvant temozolomide to a total dose of 60 Gy. Tumor residues in postresection PET and MRI were together defined as gross tumor volumes for radiotherapy treatment planning. [11C]methionine (MET)-PET/MRI was performed before RCT and at each follow-up.

Results: The primary hypothesis of a longer TTR for patients without increased tracer accumulation in postoperative MET-PET was confirmed in 89 patients. With 18.9 months (95% confidence interval, 9.3–28.5 months), median TTR was significantly (P < 0.001) longer for patients without (n = 29, 32.6%) as compared with 6.3 months (3.6–8.9) for patients with MET accumulation (n = 60, 67.4%) in pre-RCT PET. Although MRI often did not detect all PET-positive regions, an unfavorable impact of residual tumor in postsurgical MRI (n = 38, 42.7%) on TTR was observed [4.6 (4.2–5.1) vs. 15.5 months (6.0–24.9), P < 0.001]. Significant multivariable predictors for TTR were MRI positivity, PET-positive volume, and O6-methylguanine DNA methyltransferase (MGMT) hypermethylation.

Conclusions: Postsurgical amino acid PET has prognostic value for TTR after RCT in glioblastoma. Because of the added value of the metabolic beyond the pure structural information, it should complement MRI in radiotherapy planning if available with reasonable effort, at least in the context of maximal therapy. Furthermore, the spatial correlation of regions of recurrence with PET-positive volumes could provide a bioimaging basis for further trials, for example, testing local radiation dose escalation.

Exploration of Data Version Control as framework for managing machine learning workflows for HelmholtzAI.
The content consists of blogposts and additional code to follow along the tutorials-part.

The quantum Hall effect (QHE) is traditionally considered to be a purely two-dimensional (2D) phenomenon. Recently, however, a three-dimensional (3D) version of the QHE was reported in the Dirac semimetal ZrTe₅. It was proposed to arise from a magnetic-field-driven Fermi surface instability, transforming the original 3D electron system into a stack of 2D sheets. Here, we report thermodynamic, spectroscopic, thermoelectric and charge transport measurements on such ZrTe₅ samples. The measured properties: magnetization, ultrasound propagation, scanning tunneling spectroscopy, and Raman spectroscopy, show no signatures of a Fermi surface instability, consistent with in-field single crystal X-ray diffraction. Instead, a direct comparison of the experimental data with linear response calculations based on an effective 3D Dirac Hamiltonian suggests that the quasi-quantization of the observed Hall response emerges from the interplay of the intrinsic properties of the ZrTe₅ electronic structure and its Dirac-type semi-metallic character.

We study single crystals of the magnetic superconductor EuRbFe₄As₄ by magnetization, electron spin resonance (ESR), angle-resolved photoemission spectroscopy, and electrical resistance in pulsed magnetic fields up to 63 T. The superconducting state below 36.5 K is almost isotropic and is only weakly affected by the development of Eu²⁺ magnetic order at 15 K. On the other hand, for the external magnetic field applied along the c axis the temperature dependence of the ESR linewidth reveals a Berezinskii-Kosterlitz-Thouless topological transition below 15 K. This indicates that Eu²⁺ planes are a good realization of a two-dimensional XY magnet, which reflects the decoupling of the Eu²⁺ magnetic moments from superconducting FeAs layers.

Electrifying energy-intensive processes is currently intensively explored to cut greenhouse gas (GHG) emissions
through renewable electricity. Electrification is particularly challenging if fossil resources are not
only used for energy supply but also as feedstock. Copper production is such an energy-intensive process
consuming large quantities of fossil fuels both as reducing agent and as energy supply.
Here, we explore the techno-economic potential of Power-to-Hydrogen to decarbonize copper production.
To determine the minimal cost of an on-site retrofit with Power-to-Hydrogen technology, we formulate and
solve a mixed-integer linear program for the integrated system. Under current techno-economic parameters
for Germany, the resulting direct CO2 abatement cost is 201EUR/tCO2-eq for Power-to-Hydrogen
in copper production. On-site utilization of the electrolysis by-product oxygen has a substantial economic
benefit. While the abatement cost vastly exceeds current European emission certificate prices, a sensitivity
analysis shows that projected future developments in Power-to-Hydrogen technologies can greatly reduce
the direct CO2 abatement cost to 54EUR/tCO2-eq. An analysis of the total GHG emissions shows that
decarbonization through Power-to-Hydrogen reduces the global GHG emissions only if the emission factor
of the electricity supply lies below 160 gCO2-eq/kWhel.
The results suggest that decarbonization of copper production by Power-to-Hydrogen could become
economically and environmentally beneficial over the next decades due to cheaper and more efficient Powerto-
Hydrogen technology, rising GHG emission certificate prices, and further decarbonization of the electricity
supply.

The lysyl oxidase family of enzymes (LOXs) catalyze oxidative deamination of lysine side chains on collagen and elastin to initialize cross-linking that is essential for the formation of the extracellular matrix (ECM). Elevated expression of LOXs is highly associated with diverse disease processes. To date, the inability to detect total LOX catalytic function in situ has limited the ability to fully elucidate the role of LOXs in pathobiological mechanisms. Using LOXL2 as a representative member of the LOX family, we developed an in situ activity assay by utilizing the strong reaction between hydrazide and aldehyde to label the LOX-catalyzed allysine (-CHO) residues with biotin-hydrazide. The biotinylated ECM proteins are then labeled via biotin-streptavidin interaction and detected by fluorescence microscopy. This assay detects the total LOX activity in situ for both overexpressed and endogenous LOXs in cells and tissue samples and can be used for studies of LOXs as therapeutic targets.

Transient receptor potential channel subfamily C, member 6 (TRPC6), a non-selective cation channel
that controls influx of Ca2+
and other monovalent cations into cells, is widely expressed in the kidney.
TRPC6 gene variations have been linked to chronic kidney disease but its role in acute kidney injury
(AKI) is unknown. Here we aimed to investigate the putative role of TRPC6 channels in AKI. We used
Trpc6−/− mice and pharmacological blockade (SH045 and BI-749327), to evaluate short-term AKI
outcomes. Here, we demonstrate that neither Trpc6 deficiency nor pharmacological inhibition of
TRPC6 influences the short-term outcomes of AKI. Serum markers, renal expression of epithelial
damage markers, tubular injury, and renal inflammatory response assessed by the histological
analysis were similar in wild-type mice compared to Trpc6−/− mice as well as in vehicle-treated versus
SH045- or BI-749327-treated mice. In addition, we also found no effect of TRPC6 modulation on renal
arterial myogenic tone by using blockers to perfuse isolated kidneys. Therefore, we conclude that
TRPC6 does not play a role in the acute phase of AKI. Our results may have clinical implications for
safety and health of humans with TRPC6 gene variations, with respect to mutated TRPC6 channels in
the response of the kidney to acute ischemic stimuli.

Goal
The image quality achieved in iterative PET image reconstruction is influenced by several internal and user-settable parameters (number of iterations and subsets, PSF model, etc.). Typically, there are more than 3 user-settable parameters involved, interacting in a non-intuitive way. Reasonable settings typically are obtained interactively by try-and-error which is highly subjective. This proof-of-concept work proposes a method for automated reconstruction parameters optimization for a given, preselected image quality metric.

Methods
In out approach, we reconstruct images of cylindrical phantom with six "hot" sphere inserts simulating lesions of different sizes and target-to-background activity concentration ratios (20:1, 10:1, 5:1). 4 parameters of our in-house reconstruction tool THOR [1] were varied during optimization: no. of iterations and subsets, tube of response (ToR) radius, Gaussian post filter FWHM. As image quality metric we chose the weighted sum of standard deviation of contrast recovery coefficients of all 6 inserts (as a surrogate for image resolution), the image noise, and Gibbs artifacts. This metric is minimized with Bayesian optimization method using Gaussian process as a surrogate function. The reconstruction parameters resulting in the minimum metric value were chosen.

Results
The optimization process lasted for 50 iterations. The resulting reconstruction parameters were: no. of iterations/subsets=2/21, ToR radius=2.95mm, Gaussian filter FWHM=4.0mm. The resulting images show [4.7-5.8]mm resolution and 14% noise level. Gibbs artifacts level was found to be below 3.5%.

Conclusion
Our framework for reconstruction protocol optimization is capable of deriving reasonable reconstruction parameters in a fully automated manner. The presented approach might also be used to improve and objectify the comparison of different image reconstruction algorithms.

Literature

[1] A. Lougovski, et al., Physics in Medicine and Biology, vol.59(3), p.561, 2014

Open source has changed the world of software development significantly over the last decades. There are many prominent examples where open source software is successfully developed and widely applied, e.g., the Linux kernel, the office suite LibreOffice or the famous Python language. Computational Fluid Dynamics (CFD) is a highly specialised field and the software is characterized by a vast complexity of the underlying physics and equations. Seldom there is the “one” correct way for obtaining a solution for a given numerical problem. In this agile environment OpenFOAM established itself as the leading open source software package for numerical simulations in engineering applications, like nuclear safety research. Today it owns a significant share of the market and the OpenFOAM community is growing constantly.

There are many arguments for adopting open source software for numerical simulations. To qualify a CFD software for usage in a design process of nuclear power plants or critical infrastructure as well as safety analysis, the full access to the source code is an important prerequisite to guarantee transparency and reliability, e.g. to check the truthful implementation of methods and models, to have information about potential correction terms, to track the history of changes, to guarantee a long-term availability and independence from commercial interests of software manufacturers. For research in particular, transparency and reproducibility of results according to the FAIR principles is a fundamental requirement for good scientific work. Using open source software is a key prerequisite to fulfill these criteria. However, FAIR research requires more, because the modifications done by researchers have to be available to the research community in a referencable way. Furthermore, these references and repositories require maintenance and have to be further developed as knowledge evolves to have full transparency and reproducibility. Another benefit is the active community that usually develops around open source software and the availability of a common code base, which helps to enhance joint developments and the exchange of knowledge. Most importantly, open source software can be developed through a process of quick-turnaround releases incorporating lots of user feedback, at a scale that matches the complexity of what is being developed.

For a sustainable development of a complex piece of open source software, criteria like robustness, functionality, usability, extensibility and accessibility are very important as well as a significant number of users. For instance, users rely on the availability of the software package for various platforms, the usability of the solvers and utilities, as well as someone doing basic maintenance. OpenFOAM is designed as a library with multiple solvers, utilities and model libraries. This structure allows an enormous amount of applications, because all features can be combined in different ways, depending on the physical problem that should be analyzed. This flexibility has high demands on the robustness of the implementation and the underlying algorithms. Furthermore, extensibility has to be a main software design aspect (APIs, library structure) when adding new features or functionality, which is particular complicated for CFD software as there is typically more than one way to solve a problem and various, sometimes not compatible theories. All of these points mentioned above require a continuous maintenance and redesign of the OpenFOAM core.

Such a well maintained open source software package is the basis for the community to develop new technologies and own extensions for OpenFOAM. Unfortunately, for ease of development many users fork a stable OpenFOAM version for their implementations and features. The problem of such a fork is that it is rarely synchronized with the main development line of OpenFOAM. As a result bugs can remain unrecognized and unfixed, new features and functionality will be not available or have to be backported with big effort and sharing the code with others becomes problematic at some point. Clearly, for research the FAIR principles are hard to fulfill with such a fork. Hence, contributing features and functionality to the release would be desirable. As already pointed out OpenFOAM has an enormous field of applications, a lot of – maybe conflicting – interests of users, it is integrated into large design workflows and if it is used for safety analysis or in a certification process, all changes have to be well analyzed for side effects and documented. This incomplete list of requirements clearly illustrates that contributions have to fulfill a very high standard concerning software design, robustness, code style and maintainability.

Investing resources in contributions and discussions with core maintainers has another important aspect. One of the main benefits of open source software is that the community grows day by day and develops new fields of application, often into directions that were not foreseen when software got released. The intensive discussions during a contribution helps do broaden the understanding of new developments and technologies and their implications on the source code on both sides, contributors and core maintainers. It also allows to develop generalized, maintainable interfaces for potentially conflicting theories, such that users can pick up the new developments and develop their own ideas or apply them to new, unforeseen fields of application. For sure such discussions are non-trivial, time consuming and require willingness to compromise, but they are necessary to develop OpenFOAM in a sustainable and maintainable way.

VTT Finland and Helmholtz-Zentrum Dresden-Rossendorf have become active contributors to the OpenFOAM Foundation release over the last years, which is a challenge and requires a long term commitment. The population balance framework contributed by Helmholtz-Zentrum Dresden-Rossendorf and VTT Finland in end of 2017 will serve as an example how an effective contribution can look like and what benefits arise from such a contribution. Based on these experiences HZDR develops an extension for multiphase flows and – as presented in another contribution – coordinates the activities of the German nuclear society to develop an extension for numerical simulations in the reactor cooling system. For both extensions a close collaboration and a short way communication with the OpenFOAM Foundation and CFD Direct is established to influence the development of important interfaces, critical infrastructure and functionality done by the OpenFOAM core maintainers. This allows an effective, maintainable and sustainable development of HZDR’s extensions and an efficient development of new technologies in the field of CFD. Furthermore, due to the presence of other contributors, like the Process Engineering Consortium or VTT Finland, new functionality relevant for nuclear applications was developed for OpenFOAM in the last years without direct funding by HZDR. Prominent examples are energy conservation with realistic material properties, species diffusion modelling, tabulated material properties, dynamic mesh support in multiphaseEulerFoam or the revised film modelling interface. For sustainable development of
a complex piece of open source software, criteria like robustness, functionality, usability, extensibility and accessibility are very important as well as a significant number of users.

ACKNOWLEDGEMENTS
This work is carried out in the frame of a current research project funded by the German Federal Ministry for Economic Affairs and Energy, project number 1501604.

Cation exchange emerged as a versatile tool to obtain a variety of nanocrystals not yet available via a direct synthesis. Reduced reaction times and moderate temperatures make the method compatible with anisotropic nanoplatelets (NPLs). However, the subtle thermodynamic and kinetic factors governing the exchange require careful control over the reaction parameters to prevent unwanted restructuring. Here, we capitalize on the research success of CdSe NPLs by transforming them into PbSe NPLs suitable for optoelectronic applications. In a two-phase mixture of hexane/Nmethylformamide, the oleate-capped CdSe NPLs simultaneously undergo a ligand exchange to NH₄I and a cation exchange reaction to PbSe. Their morphology and crystal structure are well-preserved as evidenced by electron microscopy and powder X-ray diffraction. We demonstrate the successful ligand exchange and associated electronic coupling of individual NPLs by fabricating a simple photodetector via spray-coating on a commercial substrate. Its optoelectronic characterization reveals a fast light response at low operational voltages.

Computational Fluid Dynamics (CFD) is becoming an increasingly important tool for reactor safety research. Since many years, research groups in Germany and worldwide actively work on qualifying CFD methods, e.g. for the simulation of accident scenarios in the primary circuit that involve complex multiphase flow phenomena. In order to ensure a long-term availability of model developments and validation setups, German research projects funded by the German Federal Ministry of Economics and Technology (BMWi) used to be geared towards using a common reference code. Until the more recent past, the software of choice has been the proprietary code CFX, acquired by ANSYS, Inc. in 2003. However, recent company policy has led to a reduction of development efforts directed to CFX, particularly with respect to its multiphase capabilities, showing that the dependence of research projects on commercial software can be unsustainable.
In the meantime, open-source solutions have developed into an attractive alternative. A CFD simulation platform that is widely used in academia and industry is OpenFOAM, a free software package released under the GNU General Public License by the OpenFOAM Foundation (https://openfoam.org), maintained by a team of dedicated contributors. OpenFOAM constitutes a software library rather than a large monolithic solver and elements of it are combined into applications, each designed for a specific task. Users interact with the software through the command line; a graphical user interface is not distributed by the OpenFOAM Foundation and graphical post-processing needs to be done via third party tools.
Open-source implies full availability of the source code which generates several advantages, including, but not limited to, unobstructed verification, flexibility of implementing innovative concepts and no direct dependence on software manufacturers. Although the code itself is free, use of open-source software in general and OpenFOAM in particular can generate cost in other ways. Performing complex simulations is usually more demanding than with commercial codes and requires extensive knowledge about numerical methods. In order to extend the code, sufficient programming experience is needed and additional implementations must be continuously maintained to comply with changes of the programming and user interfaces, which are sometime inevitable in order to keep the core code maintainable and extensible. In the scope of nuclear reactor safety research, the associated effort is considerable and careful coordination is required in order to avoid duplicate efforts of partners and continuous availability of related research software developments.

In 2017, it was determined that for future BMWi-funded projects, CFD model developments should preferably be carried out using OpenFOAM. Since 2020, the BMWi is funding the Helmholtz-Zentrum Dresden – Rossendorf (HZDR) to coordinate, gather and deploy current and future OpenFOAM developments from German research projects related to the reactor cooling system. In the past years, HZDR has gained experience with the development process of OpenFOAM by frequently contributing code for inclusion in the official development line. In order to preserve German OpenFOAM developments from nuclear research activities that are not intended for contribution, HZDR has created an OpenFOAM addon called OpenFOAM_RCS, wherein RCS stands for reactor cooling system. The addon is developed and maintained with the software development environment GitLab, using an instance provided by the Helmholtz Federated IT Services. Based on the version control management system Git, GitLab provides the required tools for managing the process of continuous integration and development (CI/CD). Through the use of CI/CD-pipelines, code from partners that is intended for inclusion can be tested with respect to style aspects and, more importantly, whether it impedes previous developments. Build tests help to ensure that the code can be compiled at all times and unit tests allow to continuously verify added functionality. Finally, simulation setups from partners are archived in a separate repository and automatically tested as well to make sure that they keep functioning and deliver the expected results.
OpenFOAM_RCS includes a Doxygen-generated source code documentation. Members can effectively communicate about developments through the Mattermost chat service. The addon is deployed in precompiled form as a Docker image that includes all dependencies. Next to the option of compiling the source code themselves, partners can use it to conveniently run OpenFOAM_RCS on any operating system in a containerized form.

In many countries, spent nuclear fuel and high-level radioactive waste from operation of nuclear power plants will be stored in deep geological repositories. Thick steel casks are used to prevent the release of radionuclides into the environment. Steel is known to slowly corrode under repository conditions forming mixed iron oxides e.g. magnetite (Fe3O4). It is expected that after a long corrosion period of several ten thousand years, the steel casks may breach and long-lived radionuclides (e.g. plutonium (Pu), technetium (Tc)) may get in contact with the steel oxidation products. Such interaction can result in the formation of surface complexes or incorporation of the radionuclides into the crustal structures. The pre-dominance of one or another mechanism will strongly affect the retention and transport of long-lived hazardous radionuclides. The mechanism of these reactions, especially the structural relationships at the solid-liquid interface and adsorption kinetic, are poorly understood at the atomistic scale. This project further investigates the redox sensitive uptake of Tc and Pu at the surface of magnetite under incorporation of these elements into the magnetite structure combining atomistic simulations and X-ray absorption spectroscopy1,2.
The necessary preparatory step in this study is the identification of dominant low index surfaces on nano-magnetite particles and their termination at the relevant conditions. The atomistic simulations based on the Kohn-Sham density functional theory (DFT) are performed using the open source CP2K code. For highly correlated chemical elements such as iron (Fe), a correction due to the highly localized 3d electrons is necessary and can be achieved by utilizing the DFT+U method. Initially, the Hubbard U parameter has been determined similar to earlier investigations3 by comparing the experimental cell constants and the band gap. The preferential magnetite orientation plane (111) with six different surface terminations are examined as function of oxygen or water fugacity.

1 R. Kirsch, D. Fellhauer, M. Altmaier, V. Neck, A. Rossberg, T. Fanghänel, L. Charlet and A. C. Scheinost, Environmental Science & Technology, 2011, 45, 7267–7274.
2 E. Yalç𝚤ntas, A. C. Scheinost, X. Gaona and M. Altmaier, Dalton Transactions, 2016, 45, 17874–17885.
3 A. Kéri, R. Dähn, M. Krack and S. V. Churakov, Environmental Science & Technology, 2017, 51, 10585–10594.

Recent measurements on the dissolution rate of nano- and micron-scale rough calcite surfaces have shown lateral variations in dissolution rate, which can be quantified using rate spectra. This study uses numerical simulations to investigates the hydrodynamic processes during such experiments to explore whether hydrodynamic effects can explain the observed dissolution rate spectra. For this purpose, we simulated the dissolution processes of nano- and micron-scale rough calcite surfaces in COMSOL Multiphysics. We imposed surface topographies and local reaction rates measured using Vertical Scanning Interferometry (VSI), and implemented the same flow rate (i.e., 6 × 10−8 m3 s−1), solution chemistry (pH 8.8, alkalinity 4.4 meq/kg-H2O and pCO2 10−3.48 bar) and flow-cell geometry as those used in the experiment. We have compared the simulated rate spectra against the experimentally measured values at a calcite surface having the same surface topography and reactive-flow conditions.

Simulations using a single dissolution rate for the rough calcite surface did not produce similarly wide dissolution rate spectra like those observed experimentally. Our results have shown that only by explicitly incorporating the rate spectra in the model the simulated and the measured rate spectra would match. Sensitivity analyses by varying chemical composition and flow velocity were performed to examine the effects of these parameters on the calculated rate spectra. This study concludes that for the reactive-flow regimes where dissolution rate spectra are observed experimentally, the chemical heterogeneity, topography of the crystal surface and the resulting heterogeneity in the free energy landscape at the surface play a major role in controlling the dissolution rate spectra. With the injection of more acidic (pH 2) solutions at higher velocities (i.e., 0.04 m s−1), we observed an increase in the hydrodynamics-induced rate variability at microscopically rough surfaces

Among first experimentally discovered two-dimensional (2D) ferromagnetic materials, chromium triiodide (CrI3) monolayers have attracted particular attention due to their potential applications in electronics and spintronics. However, the Curie temperature Tc of the CrI3 monolayer is below room temperature, which greatly limits practical development of the devices. Herein, using density functional theory calculation, we explore how the electronic and magnetic properties of CrI3 monolayers change upon adsorption of 3d transition-metal (TM) atoms (from Sc to Zn). Our results indicate that the electronic properties of the TM-CrI3 system can be tuned from semiconductor to metal/half-metal/spin gapless semiconductor depending on the choice of the adsorbed TM atoms. Moreover, the adsorption can improve the ferromagnetic stability of CrI3 monolayers by increasing both magnetic moments and Tc. Notably, Tc of CrI3 with Sc and V adatoms can be increased by nearly a factor of 3. We suggest postsynthesis doping of 2D CrI3 by deposition of TM atoms as a new route toward potential applications of TM-CrI3 systems in nanoelectronic and spintronic devices.

Atom migrations in single-layer 1H-MoTe₂ are studied with Cc/Cs-corrected high-resolution transmission electron microscopy (TEM) at an electron energy of 40 keV using the electron beam simultaneously for material modification and imaging. After creating tellurium vacancies and vacancy lines, we observe their migration pathways across the lattice. Furthermore, we analyze phase transformations from the 1H- to the 1T’-phase associated with the strain-induced due to the formation of Te vacancy lines. Combining the experimental data with the results of first-principles calculations, we explain energetics and driving forces of point and line defect migration and the phase transformations due to an interplay of electron-beam-induced energy input, atom ejection, and strain spread. Our results enhance the understanding of defect dynamics in 2D transition metal dichalcogenides, which should facilitate tailoring their local optical and electronic properties.

A breathing pyrochlore system is predicted to host a variety of quantum spin liquids. Despite tremendous experimental and theoretical efforts, such sought-after states remain elusive as perturbation terms and lattice distortions lead to magnetic order. Here, we utilize bond alternation and disorder to tune a magnetic ground state in the Cr-based breathing pyrochlore LiGa_1−xIn_xCr₄O₈. By combining thermodynamic and magnetic resonance techniques, we provide experimental signatures of a spin-liquid-like state in x = 0.8, namely, a nearly T²-dependent magnetic specific heat and persistent spin dynamics by muon spin relaxation (μSR). Moreover, Li NMR, ZF-μSR, and ESR unveil the temporal and thermal dichotomy of spin correlations: a tetramer singlet on a slow time scale vs. a spin-liquid-like state on a fast time scale. Our results showcase that a bond disorder in the breathing pyrochlore offers a promising route to disclose exotic magnetic phases.

We report on the synthesis, crystal structure, magnetic, thermodynamic, and electron-spin-resonance properties of the coordination complex Cu₂(pz)₃(4-HOpy)₄, separating the gapped spin-liquid, gapless Tomonaga-Luttinger-liquid, and fully spin-polarized phase. No signature of a field-induced transition into a magnetically ordered phase was found at temperatures down to 450 mK. The material bridges an important gap by providing an excellent physical realization of an almost isotropic spin-1/2 strong-rung Heisenberg ladder system with modest exchange-coupling energy and critical-field scales.

The synthesis path of the C60-Buckyball fullerene from a planar precursor developed by Scott et al. [Science, 2002, 295, 5559] is investigated with density functional theory (DFT) methods. Various theoretically possible closing paths are analysed with respect to structural and energetic properties. The initial geometries were obtained by geometric interpolation of a cardboard-like model comprising rigid rings connected by hinges, which were then fully optimized with a selection of DFT-functionals. Analysis of the fully optimised geometries shows remarkable stability of face planarity, bond lengths and bond angles for all studied geometries, indicating soundness of the “cardboard with hinges”-model for approximating reaction paths for molecules of this type. This raises hope for development of a force field description of fullerene precursor molecules that can aid in discovery and analysis of good precursor candidates for rational synthesis of new fullerenes.

The hexagonal Dy-based compound DyNiAl undergoes ferromagnetic and antiferromagnetic-type magnetic phase transitions at T_C = 30 K and T₁ = 15 K, respectively. To investigate the 4f -electronic state and quadrupole interactions in DyNiAl, we carried out ultrasonic measurements versus temperature and applied magnetic field. The transverse elastic moduli C₄₄ and C₆₆ show a prominent elastic softening originating from an interlevel ferroquadrupolar-type interaction between the ground state and excited Kramers doublets, clarified by a crystal field analysis. In magnetic fields applied along the [100] and [001] axes, we observed a field-induced phase transition. Because the quadrupole interaction is enhanced in high magnetic fields according to our calculations, we suggest a magnetic-field-induced ferroquadrupolar ordering of the electric quadrupoles O_xy and O_yz for fields applied along [100] and [001], respectively, with different quadrupolar order parameters depending on the field direction.

Recently, the Helmholtz-wide software development platform (Gitlab) has been extended with the ability to create diagrams from textual descriptions. This post will help you getting started with this new feature.

Die klinische Bereitstellung von Radiopharmaka für diagnostische und therapeutische Zwecke ist eine der zentralen Aufgaben der konventionellen Radiopharmazie, denn sie ist das Herzstück einer jeden modernen Nuklearmedizin. Neben einem großen, aber planbaren, logistischen Aufwand ist die Versorgung mit Radiopharmaka sowohl mit radiochemischen als auch regulatorischen Herausforderungen verbunden. Das betrifft beispielsweise die zuverlässige Verfügbarkeit einzelner Radionuklide aufgrund ihrer Kurzlebigkeit und die Erfüllung obligatorischer Qualitätskontrollen.
Daneben widmen sich die Radiopharmazeutischen Wissenschaften ihrem Forschungsauftrag, der in der Erforschung neuer Radionuklide, der Entwicklung und der (prä-)klinischen Testung neuer Radiopharmaka für Diagnose und Therapie und der Weiterentwicklung der bildgebenden Verfahren SPECT und PET
sowie der hybriden Kombinationen mit MRT und CT, besteht. In diesem Sinne ist diese Ausgabe des Nuklearmediziners ganz den neuesten Entwicklungen auf dem Gebiet der Radiopharmazie gewidmet, welche sich mittlerweile über klassische Ansätze hin zu theranostischen Anwendungen in Form von diagnose-geleiteten Therapien entfaltet.

Traditionally, the primary field, where curvature has been at the heart of research, was the theory of general relativity. In recent studies, however, the
impact of curvilinear geometry enters various disciplines, ranging from solid-state physics over soft-matter physics, chemistry and biology to mathematics,
giving rise to a plethora of emerging domains such as curvilinear nematics, curvilinear studies of cell biology, curvilinear semiconductors,
superfluidity, optics, two-dimensional van der Waals materials, plasmonics, magnetism and superconductivity. Here, we summarize the state of the art
and outline prospects for future research in curvilinear solid-state systems exhibiting such fundamental cooperative phenomena as ferromagnetism,
antiferromagnetism and superconductivity. Highlighting the recent developments and current challenges in theory, fabrication and characterization of
curvilinear micro- and nanostructures, special attention is paid to perspective research directions entailing new physics and to their strong application
potential. Overall, the perspective is aimed at crossing the boundaries between the magnetism and superconductivity communities and drawing attention
to the conceptual aspects of how extension of structures into the third dimension and curvilinear geometry can modify existing and aid launching
novel functionalities. In addition, the perspective should stimulate the development and dissemination of R&D-oriented techniques to facilitate rapid
transitions from laboratory demonstrations to industry-ready prototypes and eventual products.

Density Functional Theory (DFT) is one of the most popular quantum mechanical simulation methods, since it balances sufficient accuracy with reasonable computational cost. It is often used in material science applications at ambient and extreme conditions. Nonetheless, DFT approaches its limits in terms of computational feasbility when faced with simulation problems at larger time and length scales, especially at temperatures >> 0K. Surrogate models based on neural networks can circumvent these limitations. By training a neural network to predict properties of interest (total energy, atomic forces) based on atomic configurations, predictions with DFT-like accuracy can be done at a fraction of the computational cost. At CASUS, the Matter under Extreme Conditons department is currently developing the Materials Learning Algorithm (MALA) python package, a modular open-source python package intended to serve as a toolbox for efficiently building these surrogate models. MALA enables users to preprocess DFT data, train networks and postprocess results using only a few lines of code.

A major hindrance in utilizing uranyl(VI) luminescence as a standard analytical tool, for example, in environmental monitoring or nuclear industries, is quenching by other ions such as halide ions, which are present in many relevant matrices of uranyl(VI) speciation. Here, we demonstrate through a combination of time-resolved laser-induced fluorescence spectroscopy, transient absorption spectroscopy, and quantum chemistry that coordinating solvent molecules play a crucial role in U(VI) halide luminescence quenching. We show that our previously suggested quenching mechanism based on an internal redox reaction of the 1:2-uranyl−halide-complex holds also true for bromide-induced quenching of uranyl(VI). By adopting specific organic solvents, we were able to suppress the separation of the oxidized halide ligand X2·− and the formed uranyl(V) into fully solvated ions, thereby “reigniting” U(VI) luminescence. Time-dependent density functional theory calculations show that quenching occurs through the outer-sphere complex of U(VI) and halide in water, while the ligand-tometal charge transfer is strongly reduced in acetonitrile.

Selective removal of ions from water, via capacitive deionization (CDI), is relevant for
environmental and industrial applications like water purification, softening, and
resource recovery. Prussian blue analogues (PBAs) are proposed as an electrode
material for selectively removing cations from water, based on their size. So far, PBAs
used in CDI have been selective towards monovalent ions. Here, we introduce
vanadium hexacyanoferrate (VHCF), a PBA, as a new electrode material in a hybrid
CDI setup, to selectively remove divalent cations from water.
These electrodes preferred divalent Ca 2+ over monovalent Na + , with a separation
factor, β Ca/Na ≈ 3.5. This finding contrasts the observed monovalent ion selectivity
by PBA electrodes. This opposite behavior was rationalized by Density Functional
Theory (DFT) simulations. Furthermore, the coating of the VHCF electrodes with a
conducting polymer (poly-pyrrole, doped with poly-styrenesulphonate, PPy/PSS)
prevented the contamination of the treated water following the degradation of the
electrode. This facile and modular coating method can be effortlessly extended to other
PBA electrodes, limiting the extent of treated water contamination during repeated
cycling in CDI. This study paves the way for tunable selectivity while extending the
library of electrodes that can be successfully used in (selective) CDI.

The recent rediscovery of the “Flash-effect” revived the interest in high dose-rate radiation effects throughout the radiobiology community, promising protection of normal tissue, while simultaneously not altering tumour control. Several preclinical and clinical studies are presently dedicated to electron FLASH with Linacs. However, the mechanisms of Flash is still unresolved albeit its clear impact in tissue sparing to radiation toxicity. For protons, the Flash effect was confirmed in a few animal experiments using the beam parameters available at clinical cyclotrons.
Laser-driven proton accelerators offer the possibility to extend the range of proton beam parameters to higher dose rates enabling the investigation in vivo of high dose-rate effects for up to 10^9 Gy/s. The general applicability of these beams for radiobiological studies was proven with simple cellular models and zebrafish embryos. One-step further, systematic in vivo experiments were prepared with a proof-of-principle mouse irradiation campaign at the Draco laser accelerator and, for comparison, at the University Proton Therapy Dresden (UPTD). Moreover, to investigate the interplay of oxygen tension, oxygen consumption and proton dose rate in more detail, an experiment with zebrafish embryos was performed at both proton sources.
At the conference, we will give an overview of our radiobiological experiments performed at both DRACO and Oncoray/UPTD, for different dose rates and varying oxygen pressures.

Abstract
Radiotherapy is one of the curative treatment options for localized prostate cancer (PCa). The curative potential of radiotherapy is mediated by irradiation-induced oxidative stress and DNA damage in tumor cells. However, PCa radiocurability can be impeded by tumor resistance mechanisms and normal tissue toxicity. Metabolic reprogramming is one of the major hallmarks of tumor progression and therapy resistance. Specific metabolic features of PCa might serve as therapeutic targets for tumor radiosensitization and as biomarkers for identifying the patients most likely to respond to radiotherapy. The study aimed to characterize a potential role of glutaminase (GLS)-driven glutamine catabolism as a prognostic biomarker and a therapeutic target for PCa radiosensitization.
Methods: We analyzed primary cell cultures and radioresistant (RR) derivatives of the conventional PCa cell lines by gene expression and metabolic assays to identify the molecular traits associated with radiation resistance. Relative radiosensitivity of the cell lines and primary cell cultures were analyzed by 2-D and 3-D clonogenic analyses. Targeting of glutamine (Gln) metabolism was achieved by Gln starvation, gene knockdown, and chemical inhibition. Activation of the DNA damage response (DDR) and autophagy was assessed by gene expression, western blotting, and fluorescence microscopy. Reactive oxygen species (ROS) and the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) were analyzed by fluorescence and luminescence probes, respectively. Cancer stem cell (CSC) properties were investigated by sphere-forming assay, CSC marker analysis, and in vivo limiting dilution assays. Single circulating tumor cells (CTCs) isolated from the blood of PCa patients were analyzed by array comparative genome hybridization. Expression levels of the GLS1 and MYC gene in tumor tissues and amino acid concentrations in blood plasma were correlated to a progression-free survival in PCa patients.
Results: Here, we found that radioresistant PCa cells and prostate CSCs have a high glutamine demand. GLS-driven catabolism of glutamine serves not only for energy production but also for the maintenance of the redox state. Consequently, glutamine depletion or inhibition of critical regulators of glutamine utilization, such as GLS and the transcription factor MYC results in PCa radiosensitization. On the contrary, we found that a combination of glutamine metabolism inhibitors with irradiation does not cause toxic effects on nonmalignant prostate cells. Glutamine catabolism contributes to the maintenance of CSCs through regulation of the alpha-ketoglutarate (α-KG)-dependent chromatin-modifying dioxygenase. The lack of glutamine results in the inhibition of CSCs with a high aldehyde dehydrogenase (ALDH) activity, decreases the frequency of the CSC populations in vivo and reduces tumor formation in xenograft mouse models. Moreover, this study shows that activation of the ATG5-mediated autophagy in response to a lack of glutamine is a tumor survival strategy to withstand radiation-mediated cell damage. In combination with autophagy inhibition, the blockade of glutamine metabolism might be a promising strategy for PCa radiosensitization. High blood levels of glutamine in PCa patients significantly correlate with a shorter prostate-specific antigen (PSA) doubling time. Furthermore, high expression of critical regulators of glutamine metabolism, GLS1 and MYC, is significantly associated with a decreased progression-free survival in PCa patients treated with radiotherapy.
Conclusions: Our findings demonstrate that GLS-driven glutaminolysis is a prognostic biomarker and therapeutic target for PCa radiosensitization.

The field of 2D materials has gained a lot of attention for vast range of applications. Amongst others, the sensing ability towards harmful gases is the application, which we explored in the present work using quantum-mechanical simulations for the SnP3 material. Its electronic properties, namely 1 and 2 layers being semiconducting, while multilayers being metallic, offer a possibility to build a single-material logical junction with strongly reduced Schottky barrier. In addition, the harmful gases studied here all show physical adsorption with charge transfer from the substrate to the gas molecules. Calculated recovery times show promise of a good sensing material. The I-V characteristics calculated for all cases indicate that SnP3 could be a viable sensing material towards NO gas via negative differential resistance.

In this paper, the front-end circuit of a capacitance wire-mesh sensor (WMS) is analyzed in detail and a new methodology to tune its feedback gains is reported. This allows, for the first time, a capacitance WMS to be able to provide linear measurements of multiphase fluids with electrical conductivity greater than 100 uS/cm, which is particularly important for tap water, where the conductivity is typically in between 100-500 uS/cm. Experimental and numerical results show that the selected gains using the proposed methodology contribute to suppress cross-talk and energy losses, which in turn, reduces considerably the deviation of the conductivity measurement and the estimation of derived flow parameters, such as local and average phase fraction.

The receptor tyrosine kinase c-MET activates intracellular signaling and induces cell proliferation, epithelial-to-mesenchymal-transition and migration. Within the present study, we validated the prognostic value of c-MET in patients with head and neck squamous cell carcinoma (HNSCC) treated with radio(chemo)therapy using the Cancer Genome Atlas database and found an association of increased MET gene expression and protein phosphorylation with reduced disease-specific and progression-free survival. To investigate the role of c-MET-dependent radioresistance, c-MET-positive cells were purified from established HNSCC cell lines and a reduced radiosensitivity and enhanced sphere-forming potential, compared to the c-MET-depleted cell population, was found in two out of four analyzed cell lines pointing to regulatory heterogeneity. We showed that c-MET is dynamically regulated after irradiation in vitro and in vivo. Interestingly, no direct impact of c-MET on DNA damage repair was found. The therapeutic potential of eight c-MET targeting agents in combination with irradiation demonstrated variable response rates in six HNSCC cell lines. Amongst them, crizotinib, foretinib, and Pha665752 exhibited the strongest radiosensitizing effect. Kinase activity profiling showed an association of crizotinib resistance with compensatory PI3K/AKT and MAP kinase signaling. Overall, our results indicate that c-MET is conferring radioresistance in HNSCC through modulation of intracellular kinase signaling and stem-like features.

Thin film magnetoelectric antiferromagnets (AF) is a viable material science platform for prospective high speed and energy efficient spintronic devices for memory and logic applications. To explore their application potential, it is necessary to understand modifications of the magnetic properties of AF thin films with respect to their bulk counterparts. Here, we will discuss spintronics, magnetometry and microscopy of bulk α-Cr2O3 single crystals [1] and relate them to the properties of α-Cr2O3 thin films [2-5]. In transport experiments, we access the magnetic state of the Cr2O3 relying on the spin Hall physics in a Pt thin film brought in proximity to the insulating antiferromagnet [2-4]. The analysis of the transport data is backed up by the real space imaging of AF domain patterns using NV microscopy [1,5]. Considering grainy morphology of thin films, we address questions regarding the change of the intergranular exchange [5], criticality behavior and switching of the order parameter [2] and physics of the readout signal in α-Cr2O3 interfaced with Pt [3]. In particular, the possibility to read-out the antiferromagnetic order parameter all-electrically enables a new recording concept of antiferromagnetic magnetoelectric random access memory (AF-MERAM) [3]. Furthermore, relying on the elasticity of antiferromagnetic domain walls in Cr2O3 single crystals and exploring their efficient pinning at lithographically defined mesa structures, the concept of domain wall based antiferromagnetic memory was put forth [1].

1. N. Hedrich, K. Wagner, O. V. Pylypovskyi, B. J. Shields, T. Kosub, D. D. Sheka, D. Makarov, P. Maletinsky, Nature Physics, (2021), doi:10.1038/s41567-020-01157-0.
2. T. Kosub, M. Kopte, F. Radu, O. G. Schmidt, D. Makarov, Physical Review Letters, 115 (2015) 097201.
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Motion sensing is the primary task in numerous disciplines including industrial robotics, prosthetics, virtual and augmented reality appliances. In rigid electronics, rotations, displacements and vibrations are typically monitored using magnetic field sensors. Here, we will discuss the fabrication of flexible, stretchable and printable magnetoelectronic devices. The technology platform relies on high-performance magnetoresistive and Hall effect sensors deposited or printed on ultrathin polymeric foils. These skin compliant flexible and printable magnetosensitive elements enable touchless interactivity with our surroundings based on the interaction with magnetic fields, which is relevant for smart skins, soft robotics and human-machine interfaces.

Conventional magnetic field sensors are fabricated on flat substrates and are rigid. Extending 2D structures into 3D space relying on the flexible electronics approaches allows to enrich conventional or to launch novel functionalities of spintronic-based devices by tailoring geometrical curvature and 3D shape. Here, we will briefly review fundamentals of 3D curved magnetic thin films [1] and primarily focus on their application potential for eMobility [2,3], consumer electronics, virtual and augmented reality [4-7] appliances. The technology platform relies on high-performance magnetoresistive and Hall effect sensors fabricated on ultrathin polymeric foils [8] and paves the way towards skin-compliant devices enabling touchless interactivity with our surroundings. Flexile magnetosensitive elements impact emerging research and technology fields of smart skins, soft robotics and human-machine interfaces. In this talk, recent fundamental and technological advancements on flexible magnetoelectronics will be reviewed.

[1] R. Streubel, D. Makarov et al., J. Phys. D: Appl. Phys. (Review) 49, 363001 (2016).
[2] M. Melzer, D. Makarov et al., Adv. Mater. 27, 1274 (2015).
[3] I. J. Mönch, D. Makarov et al., IEEE Trans. Magn. 51, 4004004 (2015).
[4] G. S. Cañón Bermúdez, D. Makarov et al., Science Advances 4, eaao2623 (2018).
[5] G. S. Cañón Bermúdez, D. Makarov et al., Nature Electronics 1, 589 (2018).
[6] P. N. Granell, D. Makarov et al., npj Flexible Electronics 3, 3 (2019).
[7] J. Ge, D. Makarov et al., Nature Communications 10, 4405 (2019).
[8] D. Makarov et al., Appl. Phys. Rev. (Review) 3, 011101 (2016).